Shijuan Li
email: lishijuan@mail.caas.net.cn

Yeping Zhu

Application and demonstr ation of Digital Maize Planting and Management System

Keywords: Maize, Digital management, Demonstration 1

Cooperating with Agriculture and Animal Husbandry Administrative Bureau of Dingxing County, Hebei province, we applied the agricultural information software of Digital Maize Planting and Management System to guide local maize production. This system can direct the maize production during the whole course including digital simulation and design of maize production, planting plan before sowing, optimal water and nitrogen operation, nitrogen pollution warning, economic benefits analysis and so on. This study tries to establish the foundation for

Despite of the fast development of crop simulation model in foreign countries, only a few models can be applied to production successfully. At present its main function is to forecast yield. The rapid evolution and maturity of the technologies of GIS, RS, GPS, grid, computer provide better foundation and wider development prospect for the regional application of crop simulation model [START_REF] Yang | Application of 3S Technologies on Agricultural Production in China[END_REF][START_REF] Sun | A Summary of Precision Agriculture and the"3S"Technologies[END_REF][START_REF] Wu | Information construction of prime farmland at county level based on 3S technology[END_REF][START_REF] Li | Study on digital maize management system based on model[END_REF]. Relying on the task of "Key Technology Study on Crop Production Management and Application", combining with Agriculture and Animal Husbandry Administrative Bureau of Dingxing County, Hebei province, we studied the application and demonstration of maize production management system [START_REF] Zhu | Agent-based cooperative analysis and decision support system for regional agricultural economic information[END_REF]14]. This system instructs maize production from sowing to development phases to harvest. It realizes the digital management for maize production, and will establish foundation for digital agriculture-based agricultural informalization and digitalization.

Br ief Intr oduction of System

Based on the past studies, we collected related literatures and agronomic expert information in a large scale, then designed maize cooperative models in accordance with the relationship among crop, environment and management, then combined the models with corresponding database and repository, and constituted Digital Maize Planting and Management System by using technologies of system engineering theory, software engineering theory, computer and model simulation. Therefore, this software system based on simulation model serves for maize production management and scientific experiment.

The system simulates maize production process and yield of different varieties under different location with one day as time step. It has the following functions: 1) It simulates yield and yield components, main quality formation, dynamic change of soil water and N, water and N uptake and utilization by maize, N leaching, and shows the simulation results with form and chart directly. 2) It gives anticipative target yield and quality, variety choose, sowing date and density determination, fertilizer and water management according to user's requirement and biological environment of decision location. Based on simulation model, system analyzes maize variety, water and nutrition status, weather resource and offers assistant decision-making, such as the suggestions on optimal variety, sowing date and density, the amount and time of irrigation and fertilizer. 3) Maize 3D visualization shows maize growth vividly, and it is the real reflect of simulation results from model.

System application covers the whole production process. Before sowing it makes digital simulation and design for maize production, and provides the planting scheme such as optimal sowing date and cultivar. In the course of production, it can provide the reasonable water and N fertilizer application rate, and present warning for N fertilizer pollution. After harvest the production benefit analysis can be done. The user can consult the massive information about maize production and view the 3dimension growth process visually at any time.

System Optimality and Simplification

This universal system can be used to most areas which grow food crops. Hebei province is a vital demonstration base for us. When we communicated with the technicians working in Dingxing county, they considered the system was too professional to satisfy the demand of plentiful and complicated parameters. They don't know the special meaning of some parameters at all. According to the demand of demonstration region, we redesigned the model framework to improve the practicability and maneuverability under the premise of retaining the model precision to the full. Fig. 1 showed the part of system interfaces. Data collection and analysis which drive the model are another important question, and model calibration and validation need a great deal of observed data. But there's no agricultural experiment on demonstration station before, so the lack of data accumulation prevents the simulation model application.

On the basis of enough demand investigation and local production analysis, we collected, sorted out and analyzed information required by model system such as the meteorology material (daily maximum temperature, daily minimum temperature, solar radiation, precipitation), soil property, variety characteristic (name, yield, spike number, kernel number, kernel weight and management).

In order to reduce the experimental cost, we collected the data which were useful for model calibration from the other tasks conducted on demonstration station. For example, the partial data of local formula fertilization experiment can be used to modify and check parameters of maize simulation model in order to get the variety characteristic parameters. At the same time, for the necessary data which can't be acquired directly, we arranged the detailed experiment to get managed by special technician. According to above data the database of six characteristic parameters for local common varieties was constructed with the identification program. With the work of the staffs engaging in computer, agronomy and the local extension department, system localization was done and the Digital Maize Planting and Management System for demonstration region was built and applied in practice. The relative validation items were set such as growth stages, yield, grain quality, irrigation, fertilizer application. The simulated and observed data were compared again and again until the model system can make prediction and decision accurately. Then the large-scale extension and application were carried out. Design of Exper iment 2.7 hectares located in Hebei Changli Technological Zone were chosen as demonstration area to test the optimal irrigation and fertilization function of model system. This module provides the corresponding management after running the model according to the given irrigation and fertilization indexes. The former index means the ratio of practical transpiration to potential transpiration. The latter means the ratio of N demand to N supply. We presumed all of these two indexes were 0.5, i. e. in the simulation process system recorded once irrigation or fertilization if only the index was less than 0.5. The selected field with homogeneous property possessed 1.1% organic matter, 94 kg/mg alkaline hydrolysis nitrogen, 32 kg/mg available P content, 147 kg/mg available k content. One convenient weather station named Weatherhawk made in America collected the real-time meteorology data for instance daily maximum temperature, daily minimum temperature, precipitation and solar radiation which are the drive factors of model system. Half of the area was taken as regulation field which was managed in terms of local measures, i. e. all of the 600kg/ha fertilizer was applied as base manure; maize was irrigated at jointing stage and tasselling stage respectively. The other half was used to demonstrate the model system, i. e. maize was irrigated or fertilized according to the recommendation measures offered by system. Maize production process was simulated at three stages of before sowing, jointing and tasselling. Before sowing maize yield and the rate and time of irrigation and fertilization were simulated on the basis of the basic data about perennial meteorology, soil property and variety characteristic. At jointing stage maize yield and the amendatory irrigation and fertilization application were provided on the basis of the basic data of the real weather material between sowing and jointing, perennial meteorology after jointing, soil property and variety characteristic. At tasselling stage the simulation was done again by using the real meteorology data between sowing and tasselling. The first simulation result meant 450 kg/ha and 300 kg/ha N fertilizer would be applied as base manure and top-dressing in jointing stage respectively; irrigation of 90mm in jointing stage and 70mm in tasselling stage would be needed. The second recommended management was that 225 kg/ha N fertilizer should be applied as top-dressing in jointing stage and no irrigation. The third recommended result indicated there were no need for fertilizer and irrigation.

The local conventional irrigation management is irrigating maize twice in jointing and tasselling stages. The precipitation was enough for maize growth in 2009, so above two stages needed no irrigation. For demonstration field the simulation result before sowing indicated the demand of irrigation in jointing stage, yet the second predicting result showed there's no need for irrigation. Here we adopted the latter simulation result because it was based on partial practical meteorology data. Therefore in this study there was no irrigation whether for regulation field or for demonstration field.

The other materials and production manner were same for these two treatments. The maize with variety of Sanbei 21 and density of 57 000 plants per hectare was sowed in 18 th June, 2009, and was harvested in 10 th October, 2009. The fertilizer used was special manure for formula fertilization (N:P:K=26:10:6).

Yield Compar ison

Every treatment had been harvested individually. Then the yield and kernel weight were measured. We chose 20 spikes to account the kernel number per spike stochastically. The fertilizer applied in jointing stage acts on maize growth mainly from jointing to tasselling, which is the key period to decide kernel number. Below table showed the kernel number was increased distinctly and the kernel weight was a little improved in demonstration field compared with conventional field. Using this software to guide maize production indicated that adding N fertilizer 75 kg/ha resulted in a 768 kg/ha yield increase, and had significant enhancement on economic benefit.

Conclusion

The agricultural software based on simulation model of Digital Maize Planting and Management System was well-done in theory. This system can instruct maize production from sowing to development phases to harvest. In order to verify and perfect it we applied it in maize production management process in Dingxing county, Hebei province. The system predicted that the maize growth needed more N fertilizer than conventional N management. The results indicated that adding N fertilizer 75 kg/ha resulted in a 768 kg/ha yield increase, and had significant enhancement on economic benefit. The performances of currency and universality for model system can be explained difficultly because of the small demonstration area and only one-year experiment result. So we intend to enlarge the extension region and increase the demonstration content to promote the application of crop simulation model.

Fig. 1 .

 1 Fig. 1. System interface.

Table 1 .

 1 Yield and yield components for conventional field and demonstration field.

		Spike number	kernel number	100 kernel	Yield
		per ha	per spike	weight(g)	(kg/ha)
	conventional field	57 000	434.3	33.4	7110.0
	demonstration field	57 000	459.2	35.0	7878.0

Acknowledgments. This research is kindly supported by Special Fund of Basic Scientific Research and Operation Foundation for Commonweal Scientific Research Institutes and Beijing Nova program.


Jun Du

Peiling Yang
email: yangpeiling@126.com

Yunkai Li
email: liyunkai@126.com

Shumei Ren
email: renshumei@126.com

Xianyue Li

Yandong Xue
email: xueyandong1104@yahoo.cn

Lingyan Wang
email: wanglingyan@163.com

Wei Zhao

An Analysis on the Inter-annual Spatial and Temporal Variation of the Water Table Depth and Salinity in Hetao Irrigation District, Inner Mongolia, China

Keywords: Hetao Irrigation District, Depth water table, groundwater salinity, spatial and temporal variation

de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The HID (40°19′-41°18′ N, 106°20′-109°19′ E) is one of the three largest irrigation districts in China and be located the arid western part of Inner Mongolia Autonomous Region, China (Fig. 1). The total land area of the HID is about 1.1×10 4 km 2 , the irrigable land area is about 0.77×10 4 km 2 , but due to salinity problems, the currently irrigated land area is only about 0.57×10 4 km 2 . HID is in the mid-temperate zone with continental-monsoon arid climate. The weather is dry and hot during summer and severely cold with little snow in winter. From November to next March is a freeze-thaw period. Mean annual temperature is 6.3~7.7℃. During the winter the average air temperature are -10 °C and the soil freezing depths about 1.0 m. The average annual pan evaporation is about 2164 mm. Across HID, the average annual precipitation 168 mm recently 10 years. The the average ground slope is about 1/8000~1/4000 (from southwest to northeast). The ground elevation ranges from 1043 m to 1018 m. The main soil types are irrigation-warping soil and saline soil which was the non-zonal soils in HID. The average soil bulk density(0-100cm) is 1.45 g/cm 3 (Yang [START_REF] Jingyu | Determination and Evaluation on Soil Water Retention Curve Model in Hetao Irrigation District[END_REF].

The most common crops are sunflower, wheat, and corn. Flood irrigation is the most common irrigation method in the HID. The average depth of irrigation is 450 mm. Farmland is typically irrigated 7 times each year in 3 irrigating seasons. The 3 irrigation seasons are: summer irrigation (3 irrigation times, from April to June), the first-autumn irrigation (3 irrigation times, from July to September), and the second-autumn irrigation (1 irrigation times, from October to November). The summer and first-autumn irrigation are during the growing season of the crop. The purpose of the second-autumn irrigation period is to "bank" soil water and leach salt. From 1989 to 2005, the average annual water diversion of irrigation from the Yellow River is 5.2×10 9 m 3 by 1 main canal and 13 sub-main canals. Farmland recession water is drainage into the Wuliangsuhai Lake (Fig. 1) by 1 main ditch and 10 sub-main ditches [START_REF] Xusheng | Analysis on Water Cycling in GSPAC System of Hetao irrigation District in InnerMongolia, China[END_REF], and the average annual drainage amount was 0.5×10 9 m 3 . The water diversion of irrigation in 2001, 2002 and 2003 was 4.89×10 9 m 3 ,5.08×10 9 m 3 and 4.1×10 9 m 3 respectively. The salts which are brought by the irrigation water onto the farmland soil averages annually 235.5×10 8 kg, but the average annual discharged salt from the entire district by drainage is only 75.0×10 8 kg [START_REF] Xusheng | Analysis on Water Cycling in GSPAC System of Hetao irrigation District in InnerMongolia, China[END_REF]. For the period from 1987 to 1997, the average annual salt accumulation was estimated to be 3 mg/ha [START_REF] Zhaozhong | : Influence of autumn irrigation on soil salt leaching of different farmlands in HID of Inner Mongolia[END_REF]. About half of the irrigated cropland is saline-alkali soil [START_REF] Zhaozhong | Feng Zongwei:Soil N and salinity leaching after the autumn irrigation and its impact on groundwater in HID, China[END_REF]. DWT is typically 1.0~1.5 m during the growing season and about 0.5 m following the second-autumn irrigation (from October to November) (Hao et al., 2008a).

Due to the arid climate, the water diversion from Yellow River is critical for agriculture in the HID. There are significant negative effects from flood irrigation and canal seepage. The resulting shallower DWT combined with intensive evaporation has produced a very high threat of soil salinization. About 18.8% of the total land area in the irrigation district has been abandoned because of the salinization problem, and about 43.0% of the irrigated area is significantly impacted salinization problem of various degrees [START_REF] Zhongyi | The Prediction of Water and Salt Regime and Effect Evaluation of Water-Saving Reform Project in Large-Scaled Irrigation District China Rural Water and Hydropower[END_REF]. Geological structure, geographical conditions, and climate factors determine the hydrological cycle and the resulting potential for salinization. In HID, there are many factors affecting the salinity such as precipitation, evaporation, DWT, and water diversion irrigation from Yellow River [START_REF] Weiguang | Spatial Variability of Water Level in HID Inner Mongolia and Their Estimations by the Kriging.Journal of Irrigation and Drainage[END_REF][START_REF] Yue Yun | Spatial Variability of GWS in HID Inner Mongolia[END_REF]. The geological structure determines that the major hydrologic Fig. 1 Map of Irrigation District located and observation wells distribution pathway for groundwater loss away from the HID is through the phreatic evaporation (Hao et al., 2008a). And the accumulated salt in the deeper soil were dragged into the surface soil in this process. So, the process of groundwater discharge is the dominated factors related to the production, development, and evolution of the soil salinization in HID. Irrigation (precipitation), infiltration, drainage, and groundwater evaporation, create the natural-artificial surface water system that is the most important factor in hydrological cycle for the HID (Hao et al., 2008a).

A previous study showed that shallower groundwater had a significant effect on evaporation-transpiration and on soil water salinity. Evaporation exacerbated the surface soil water salinity, while the transpiration reduced the soil water salinity in the growth period of vegetation [START_REF] Deqiang | Study on the variation and influence factor of soil2water mineral degree in shallow groundwater areas[END_REF]. Climate condition and groundwater level fluctuation were the major environmental factors on the salinization of soil (Chen et al., 1997). Some studies on the salinity and DWT in HID showed that DWT is in 1.5m~2.0m contribute to the crops uptake the groundwater, but to minimize salinizion, DWT should be controlled below 2.0m from the soil surface (Kong, 2009). When the water diversions from the Yellow River to the HID were reduced by 30%, there was resulting higher of DWT and reduction in salinity soil, but there was greater potential for soil water deficit and crop water stress. [START_REF] Zhongyi | The Prediction of Water and Salt Regime and Effect Evaluation of Water-Saving Reform Project in Large-Scaled Irrigation District China Rural Water and Hydropower[END_REF]. Other researchers have reported on the soil salinization issues in HID such as: saline land improvement, the relationship between the soil salinization and the DWT, the distribution of salt in the soil profile, the salt balance, and the water balance (Yang et a1.,2003 ;Kong,et a1.,2004;Wang et a1., 2004;Jia et a1.,2006;Gao et a1., 2008a,b). But there are very few studies on the distribution of DWT and groundwater salinity in the entire HID. Therefore, this report is an analysis of the spatial and temporal variation of the DWT and groundwater salinity.

Materials and Methods

DWT measurement and water samples analysis

In this analysis, the HID was divided into 5 irrigated areas: Yigan, Jiefangzha, Yongji, Yichang and Wulate (Fig. 1). There were 178 wells (Fig. 2) distributed over the entire District. Seventy-five wells were used to observe the DWT, 42 wells were used to collect groundwater samples, while 61 well were used for both DWT and water samples.

The water quality analysis was performed at the Bayannur Water Conservancy-Science Institute Laboratory, Linhe, China. The constituent ions included: Na + and K + (determined by the flare photometer method), Ca 2+ and Mg 2+ (determined by EDTA titration), CO 3 2-and HCO 3-(determined by the acid titration), CL -(determined by AgNO 3 titration method), SO 4 2-(determined by EDTA indirect titration method).

DWT was measured directly by a measuring tape with a detector at the end (Fig. 2). The detector gave a signal when it reached the water surface and the length of the tape was recorded. Depth to groundwater table was calculated by subtracting the above ground wells' body height (L 1 ) from the recorded length of the tape. DWT calculate is given by: DWT=L-L 1 (1) Where DWT is the distance from the ground surface to the groundwater table. L is the distance from the well mouth to the groundwater surface. L 1 is the distance from the well mouth to the ground surface. DWT were measured once a week. Water samples for chemical analysis were collected at 15 in every month.

Typical years and typical irrigation period

Data from 2001, 2002 and 2003 years were analyzed to determine the inter-annual variation of DWT and groundwater salinity, which will continue in time and reflects the water diversion for irrigation into the HID. Also in this analysis, the March, July, and November was taken as typical period which was the fluctuation of DWT and the variation of the shallower groundwater salinity.

Sampling site data and processing

The value of DWT and groundwater salinity of 178 observation wells were used to develop the point file with ArcGIS9.0 and project the coordinate transformation to produced the distribution map for the geo-statistical analysis (Fig. 1).Then of DWT and groundwater salinity from corresponding sampling points were entered into Arc GIS9.0 to form the attributive data to matched the geographic data of sampling points.

Correlation analysis

SPSS13.0 was used to analyze the change and relationship between DWT and shallower groundwater in March, July and November respectively. The data of DWT from 7 wells which less affected by the groundwater exploration were selected to analyzed the annual change of DWT each year (Fig.4,5,6). The data of 61 wells' DWT were as abscissa and with the corresponding salinity degree of groundwater as ordinate to make the relation curve to analyze the relationship between the groundwater salinity and DWT (Fig. 25) in March, July, and November, respectively. Geo-statistical methods and ArcGIS9.0 were used to analyze the temporal and spatial variation of DWT and groundwater salinity from 2001 to 2003. Geo-statistical methods can be used to describe the spatial variability of environment and reveal the spatial heterogeneity and spatial pattern of natural phenomena [START_REF] Pebesma | Mapping groundwater quality in the Netherlands[END_REF].

The semi-variogram model and Kriging interpolation are the two main geo-statistical methods used in this analysis [START_REF] Menggui | Temporal and spatial soil water management: a case study in the Heilonggang region, PR China[END_REF][START_REF] Sousa | Regional analysis of irrigation water requirements using Kriging Application to potato crop at TraÂs-os-Montes[END_REF]Desbarats et al., 2002;Vijendra et al., 2004;Tong et al., 2007;Wang et al., 2007;Yue et al., 2009;Hu et al.2001, 2009;Husam,2010).

To get a better spatial estimation from sampling points, the variance of estimation error should be minimal. The Kriging method was used to obtain the variance of estimate. The advantage of Kriging is that it is the Best Linear Unbiased Estimator of the unknown fields (Journel and Huijbregts, 1992).The Kriging variance of estimate is independent of the actual measurements from the field. Ordinary Kriging interpolation at a point x 0 is given by: ( ) ( )

0 1 n i i i Z x n Z x λ * = = ∑ (2)
Where Z*(x 0 ) is the estimated value, n is the number of points, Z(x i ) is the measured value at point xi, and i λ the Kriging weight. To calculate the Kriging variance, the semi-variogram is needed. The semi-variogram (usually called a variogram) is half the variance of measurement differences at all data pairs with the same distance (h). The Kriging variance is given by:

2 1 1 ( ) [ ( ) ( )] 2 h N i i i h h Z x h Z x N γ = = + - ∑ (3)
Where r(h) is semi-variogram, h is step length, namely the spatial interval of sampling points used for the classification to decrease the individual number of spatial distance of various sampling point assemblages, N(h) is the logarithm of sampling point when the spacing is h, and z(x i ) and z(x i +h) are the values when the variable Z is at the x i and x i +h positions, respectively.

Fig. 3 experimental semi-variogram (dots) and fitted semi-variogram model

When computing the semi-variance (h) for different values of h, and when h is plotted versus (h), an experimental semi-variogram was obtained (Fig. 3. [START_REF] Sousa | Regional analysis of irrigation water requirements using Kriging Application to potato crop at TraÂs-os-Montes[END_REF]. However the experimental semi-variogram is not applicable in Kriging estimation because it cannot be represented by an equation. A semi-variogram model must then be adjusted to the experimental one, as exemplified in Fig. 3 by the fitting of the Spherical equation. The best-fitted semi-variogram model has been used to produce the Kriging variance map. Selection of the best-fitted model was based on the condition that the root-mean-square was close to "0",the average standard error is minimum, the mean standardized was close to the standard error and the root-mean-square standardized was close to "1" [START_REF] Tang Guoan | Geographic information system spatial analysis experiment and course[END_REF]. Then GIS-Spatial Analyst tool in ArcGIS9.0 was used to produce a priority map and the best-fitted mode.

To obtain Kriging variance, construction of the variogram is needed. The variogram parameters are the sill, nugget, and the range. The nugget is the variogram value at the origin. Sometimes the nugget is different from zero due to measurement error. The range is the distance at which the variogram reaches the sill value. Three modules included Spherical model (Eq.4), Exponential model (Eq.5) and Gaussian model (Eq.6) were used in this study.

( ) ( )

3 0 1 ( ) [1.5 / 0.5 / ] h C C h a h a γ = + - (4) / 0 1 ( ) [1 ] h a h C C e γ - = + - (5) 2 ( / ) 0 1 ( ) [1 ] h a h C C e γ - = + - (6)
Where 0 C is nugget, which represents the spatial heterogeneity of the stochastic component. The sill value, ( 0 C C + ), is the attribute of the system or the maximum variation of the regional variables. The higher the sill value is, the larger the degree of the total spatial heterogeneity will be. The value of a is the range. Sill (C 0 +C) and nugget (C 0 ) were used to describe the spatial heterogeneity. The ratio of nugget: sill (C 0 / C 0 +C) reflected the total spatial heterogeneity [START_REF] Habin | On definition and quantification of heterogeneity[END_REF].

In this study, "Histogram" and "Normal QQplot" were the geo-statistical modules used with ArcGIS9.0. These modules were applied to analyze the normality of the 178 wells data of DWT and groundwater salinity each month. The results shown that the mean data comply with lognormal distribution. The ordinary Kriging interpolation method was applied to optimal mathematical model, and set the values of "Lag size" and "Number of lags" etc. to get the optimal predication map (Fig. 7~24) and the best-fitted model (Eq.4~6). Table 1~2 lists several models with their respective sill and nugget.

Results and Discussion

Analysis of the spatial structure of DWT and groundwater salinity

The ratio of C 0 : (C 0 +C) reflected the total spatial heterogeneity. A higher ratio indicates that the stochastic component was the main factor caused the spatial heterogeneity. The ratio of C 0 : (C 0 + C 1 ) was in the range of 25%~75% of the spatial structure of DWT in the three years(Tab. 1). It shown that the spatial structure variation of DWT was not only affected by the structure factors but also by the random factors (the stochastic component). Due to the average annual precipitation is 168 mm and the irrigation water is the mainly recharge source of DWT. So the spatial structure variation of DWT was affected by the time and amount of the agricultural irrigation mainly during the irrigation season. The structure factors such as the terrain, landform and climate would be responsible for the variation of the spatial structure of DWT when the total water diversions of irrigation were reduced. For example, although the water diversions of irrigation in 2003 were reduced to 80% of the average annual water diversions of irrigation and the ratio of C 0 : (C 0 + C 1 ) of the spatial structure of DWT in July and November decreased to 34.3 and 37.5 respectively, the distribution of DWT in July and November 2003 were similar to that of 2001 and2002(Fig. 8, 11 and14. Fig. 10, 12 and15.). Therefore, the spatial structure of DWT was the moderate spatial correlation and the average corresponding distance was 18.5 km among the three years(Tab.1). These result shown that the co-working of the structure factors and random factors were the mainly factor of the variation of the spatial structure of DWT in HID.

The table 2 shown that the ratio of C 0 : (C 0 + C 1 ) of spatial structure of groundwater salinity varied from 0.3 to 45.7 in the three years. The spatial structure of groundwater salinity had the strong spatial correlation and the average corresponding distance was 12.1km. Since the salt which in the irrigation water (the Yellow River water salt content was 480 mg/l) were the mainly recharge resource of the shallower groundwater salinity, the different water diversions of irrigation would cause the variation of the shallower groundwater salinity. Meanwhile, the waste discharge of industries and civil life also enhanced the variation of it. This result shown that the groundwater salinity was affected by the random factors, such as irrigation water salt, field fertilization and waste discharge of industries and civil life in HID. 3.2 Analysis of temporal and spatial variation of the DWT

Temporal variation of DWT

The variation of DWT of 7 wells which without the affects of groundwater exploitation were similar among the three years (Fig 4,5 and 6). Namely, the average DWT value was 2.0 m in January and reached the maximum value (2.5 m) in March, and then decreased to 1.5 m in May after the summer irrigation. Since the agriculture irrigation was gradually decreased from August to September, DWT increased to 2.2 m in September. Following the late autumn irrigation which the irrigation water amount were thirty percent of the total water diversion, the average DWT value rapidly decreased to 1.0 m in November. With the beginning of winter, the DWT gradually increased to 2.0 m by next January. Then, the fluctuation of the DWT completes the annual cycle. These peaks and valleys demonstrated that the time and amount of agricultural irrigation were responsible for the fluctuation of the DWT without the effect of irrigation exploitation in HID.

Spatial variation of DWT in typical period

Owing to the temperature difference between the upper and under boundary of the freezing soil layer, the high absorption energy makes groundwater in air containing zone move towards the freezing layer so that the DWT value of 95% area of HID were in the ranged of 2~3 m in March each year (Fig. 7, 10, 13) . Because the water diversions of irrigation were reduced to 80% of the average annual water diversions of irrigation (52×10 9 m 3 ) in 2003, and the irrigation water amount were reduced during the summer irrigation season. Therefore, the DWT value of 80% area of HID were in the range of 1.5~2.0 m, and the regions of DWT in the range of 2~3 m were continuously in July 2003(Fig. 14). Although the DWT of 80% area of HID were also in the range of 1.5~2.0 m in July 2001, the regions of the DWT in the range of 2.0~3.0 m were scattered over the southwest in HID(Fig. 11). In 2002, the total water diversions of irrigation were more than that of other two years. And the DWT value of 50% areas of HID were in the range of 1.0~1.5 m in 2002(Fig. 8). It can be drawn into conclusion that the distributional-variation of the water diversions of irrigation among years caused the distributional-variation of DWT in the entire HID. In other word, the more the water diversions of irrigation were, the shallower DWT in HID would be.

In additional, the figure 8, 11 and 14 shown that the shallower DWT region distributed in Yigan, southwestern part of Jiefangzha, minor area of Yongji and Wulate irrigation region. These regions were the agricultural areas with little in groundwater exploitation and lower terrain. While the deeper DWT regions distributed in the northeastern part of Jiefangzha, major part of Yongji and Yichang irrigation region. These regions were the agricultural areas with the higher terrain and cities-towns. And an amount of the groundwater exploitation were used to meets the demand of the domestic water, public facilities and urban greening in cities-towns.

Take 310 # , 223 # and 305 # well as example, the average annual DWT were 3.7 m, 3.5 m and 3.5 m from 2001 to 2003, which were located around the city of Linhe, Wuyuan and Qianqi respectively. In second-autumn irrigation season, there was 1 irrigation-time in HID, and the irrigation amount was 30% of the total water diversions of irrigation. And the terrain slopes gently, the average ground slope is about 1/8000~1/4000 (from southwest to northeast). Therefore, the DWT of the entire HID were in the two ranges ,namely, 0.5~1.0 m and 1.0-1.5 m in November. The range of 0.5~1.0 m distributed in Yigan, Yongji and Wulate irrigation region, and the range of 1.0~1.5 m distributed in Jiefangzha and Yichang irrigation region (Fig. 9, 12, 15). The temporal and spatial distribution of the groundwater salinity was quite similar among the three years (Fig. 16~24). There were two salinity degree zones in the northern and southern of HID, which the salinity degree was more than 5000 mg/l (red regions) and even, in some local areas, the salinity degree was more than 10000 mg/l. The northern zone was from Dashuwan (west) to Fenzidi (east), the southern zone was from Xishanzui extended to Chengnan and Shulinzi. The groundwater salinity of the major area of Hetao in March and November was M<3000 mg/l and M>4000 mg/l, respectively. The reasons caused these results were followed:

(1) Because the southwest elevation (1043 m) was higher than that of the northwest (1034 m) and the southeast (1018 m). The groundwater horizontal movement was from southwest toward the northwest and southeast. An amount of salt accumulated into the soil and penetrated into groundwater of the northwest and southeast area of HID. Therefore, the groundwater salinity in southeast and northwest were higher (M>5000 mg/l) than that of (M<3000 mg/l) the middle area of HID.

(2) The soil water was in the cycle process of the irrigation recharge and evaporation-transpiration in summer irrigation and first-autumn irrigation season. These resulted in soil salinization and high degree of groundwater salinity. Under the action of the high evaporation and transpiration, a large amount of the salt of which accumulated in deeper-soil and dissolved in groundwater were moved toward and accumulated into the surface later soil. But the accumulated salt in the surface later soil dissolved adequately into the shallower groundwater again during the second-autumn irrigation period. So, the groundwater salinity of the major area of HID in November was M>4000 mg/l. With the lateral seepage of soil water and the horizontal movement of groundwater, a lot of salt of which dissolved into soil-water and shallower groundwater was moved away HID during the period from November to the next March. Then, the groundwater salinity of the major area of HID was M<3000 mg/l in March.

Relationship between the table depth and salinity of groundwater

Under arid or semi-arid conditions and regions of poor natural drainage, there was increasing potential for hazardous accumulation of salts in soils. The salinity was important index that reflected the degree of human activities on the water quality influence of the groundwater. Meanwhile the salinity also reflected the distributing characteristics and change trend of the chemical composition of the groundwater in some regions. DWT was important as it determines the distance that contaminants had to travel before reaching the groundwater. Deep groundwater was less vulnerable than shallow aquifers. In HID, due to the agricultural irrigation water resource was mainly Yellow River water, and the average annual salinity degree of the irrigation water was 480mg/l. So, the agricultural irrigation time and amount was the mainly factors to affected the variation of the groundwater salinity. At the same time, the agricultural irrigation water were also the mainly resource to recharged the groundwater. Therefore, there was maybe certain correlation between DWT and groundwater salinity in a given temporal and spatial range. Fig. 25 (here was given the relation curve in March 2001 only, since other years' regression correlation results were similar to it.) shown that Linear regression between DWT and the groundwater salinity indicated that there were other factors than water table depth that influenced salinity of groundwater. The figure 7~24 shown that the special relationship between them in some special regions. The first relationship existed around the wetland and the lower terrain region. For example, the average annual DWT of wells 37 # and 38 # was 0.97 m and 1.01 m, and the corresponding salinity degree values were 14500 mg/l and 12800 mg/l respectively. Both wells were installed nearby Dashuwan and Daxian Lake (saline lake), respectively. The average annual DWT of wells 106 # was 0.89 m and the corresponding salinity degree values were 8000 mg/l which was installed in nearby the wetland. The average annual DWT of wells 277 # and 278 # was 0.90 m and 0.87 m, respectively, and the corresponding salinity degree values was 31700 mg/l and 31000 mg/l. Both of which were installed in nearby Xian Lake (saline lake). The second relationship was exists around the cities and towns. In the cities and towns regions, due to the recharge and exploration of groundwater balanced the fluctuation of DWT and slow down the salt accumulation in the shallower groundwater. For example, the well 310 # (Linhe city), 223 # (Wuyuan city) and 305 # (Qianqi city) which the average annual DWT were 3.82 m, 3.76 m and 3.64 m and the corresponding salinity values was 1550 mg/l, 1200 mg/l and 2900 mg/l, respectively. There were many factors which influence the variation of the table depth and salinity of groundwater such as terrain, climate condition, soil types, quality and time of irrigation water and the terrain of HID, etc. Although the linear relationship between the DWT and groundwater salinity were not significant, the distribution of DWT could reflected the distribution of the groundwater salinity in the certain regions. Namely the shallower DWT was, the higher the salinity degree of groundwater would be. The deeper DWT was, the lower the salinity degree of groundwater would be.

Conclusions

Due to insufficient data coverage, the shallower groundwater salinity studies often require interpolation or extrapolate from a few observation points into large areas. This was especially critical for groundwater aquifers with complex and extensive hydro-geological heterogeneities at extremely varying scales. The geo-statistics methods and Arc GIS were very useful for DWT and groundwater salinity studies in HID Inner Mongolia, China. The spatial structure of DWT was controlled by the terrain, landform and climate more than the random factors such as the waste discharge of industries and civil life, the time and amount of the agricultural irrigation. Therefore, DWT was the medium spatial correlation and the average corresponding distance was 18.5km in three years. The variation of the spatial structural of the groundwater salinity was mainly affected by the random factors, and it is the strong spatial correlation and the average corresponding distance was 12.1km in three years.

There were remarkable differences in the temporal and spatial variation of the recharge rate and salinity of groundwater in different irrigation regions, since their agricultural planting structure and water diversions of irrigation were different. Meanwhile, massive groundwater exploitation of living and industrial enhanced the disparity of temporal and spatial variation. However, the temporal and spatial distribution of DWT and groundwater salinity was quite similar between years (from 2001 to 2003) in HID Inner Mongolia. DWT in western, eastern area and a small part of middle area were shallower than other area in Hetao. The average annual DWT in March reached the maximum and that of in November reached its the minimum within one year. The shallower depth region of groundwater distributed in the agricultural area, and the deeper depth region of the groundwater distributed in cities and towns with higher terrain.

Due to the geological structure and geographical conditions, a large of salt accumulated into the soil and penetrated into groundwater of the northwest and southeast area of HID. In northwest and southeast area, the groundwater salinity were M>5000mg/l and even, in some local areas, M>10000mg/l. Meanwhile, the special irrigation seasons and climate made the maximum and minimum of groundwater of HID appeared in the specific period of September and March, respectively. The groundwater salinity of the major area of HID was more than 4000mg/l in November. With the lateral seepage of soil water and the horizontal movement of groundwater, some of the accumulated salt was drained away HID. The groundwater salinity of the major area of HID was less than 3000 mg/l except the northwest and southeast area in March.

There were many factors which influence the variation of the table depth and salinity of groundwater such as climate condition, soil types, quality and time of irrigation water and the terrain of HID etc, and the temporal and spatial variation of these factors was high in the different area. Therefore, the linear relationship between DWT and groundwater salinity were not significant. In some special areas, however, the distribution of DWT could reflect the distribution of the groundwater salinity. Namely the shallower DWT was, the higher the groundwater salinity degree would be. The deeper DWT was, the lower the groundwater salinity would be.

In this study, we get the characteristics of the temporal and spatial distribution of DWT and shallower groundwater salinity. We can make the rational agriculture planting structure according with these characteristics. For example, planting the crop which are the salt-resistant and drought tolerant in the high salinity areas in order to reduced the amount of the salt which were brought by the irrigation water, and to increased the amount of irrigation water in the second-autumn period to leach more soil salt. This is quite important to maintain the eco-environmental balance in HID.

  Fig.2 the observation wells' construction

Fig. 4 Fig. 5 Fig. 6

 456 Fig.4 Map of DWT variety,2001

Fig. 7 Fig. 8

 78 Fig.7 Distributing map of DWT in March, 2001

Fig. 20

 20 Fig.20 Distributing map of groundwater salinity in July, 2002

Fig. 25

 25 Fig.25 Relationship between DWT and groundwater salinity in March,2001

Table 1

 1 the parameters of semi-variogram models for shallow groundwater table depth

				Ran Nug	Par	Sill	C 0 / (C 0 + C 1 )
	Year	month Model
				km	C 0	C 1	C 0 + C 1	%
		Mar	Sph	22.7 0.15 0.11	0.26	58.2
	2001	July	Exp	11.5 0.10 0.20	0.30	51.8
		Nov	Sph	13.4 0.24 0.09	0.33	73
		March	Sph	28.4 0.04 0.01	0.05	72
	2002	July	Exp	19	0.05 0.06	0.11	46.6
		Nov	Sph	19	0.16 0.14	0.29	53.6
		Mar	Sph	22.7 0.03 0.02	0.05	52.7
	2003	Jul	Gau	19	0.04 0.08	0.13	34.3
		Nov	Exp	10.7 0.14 0.24	0.38	37.5
	mean		18.5 0.09 0.09	0.19	47.8

Table 2

 2 the parameters of semi-variogram models for shallow groundwater salinity

	year month Model	Ran Nug km C 0	Par C 1	Sill C 0 + C 1	C 0 / (C 0 + C 1 ) %
		Mar	Gau	11.1 0.05	0.68	0.72	6.4
	2001	Jul	Sph	12.3 0.11	0.64	0.74	14.3
		Nov	Gau	9.5	0.18	0.53	0.71	25
		Mar	Sph	23	0.20	0.65	0.85	23.3
	2002	Jul	Sph	13.5 0.35	0.42	0.77	45.7
		Nov	Gau	11.8 0.35	0.46	0.81	43.4
		Mar	Exp	7.9	0.04	0.79	0.83	4.7
	2003	Jul	Exp	11.5 0.11	0.68	0.79	13.8
		Nov	Exp	8.4	0.00	0.69	0.69	0.3
		mean		12.1 0.16	0.61	0.77	20.1

Acknowledgements

This study was supported by the Changjiang River scholar and creative team development plan (IRT0657), the Ministry of water resources community projects: Ecological irrigation district studies on theory basis and supporting technical system (20071025),the research cooperation projects of China agricultural university and Inner Mongolia agricultural university and China agricultural university graduate innovative research(kycx09113).


Liu Zhao
email: zhaoliu@nercita.org.cn

Hua Ping

Ling Xiang

Ping Han

Jihua Wang

Ligang Pan

{liu Zhao

Application of Molecular Imprinting Technique in Organophosphorus Pesticides Detection

Keywords: Molecularly imprinted polymers, Solid phase extraction, Organophosphorus pesticides

Molecular imprinting technique offers a means of producing practical materials that are able to recognize a certain molecule in terms of shape, size and chemical functionality. In order to obtain a highly selective recognition of organophosphorus pesticides (OPPs), we synthesized molecularly imprinted polymers (MIPs) using pirimiphos-methyl as the template, methacrylic acid as the monomer and ethylene glycol dimethacrylate as the crosslinker. After polymerization, molecularly imprinted solid-phase extraction (MISPE) was used for the selective preconcentration of OPPs. The preparation methods and synthesis conditions of MIPs were discussed, and the specificity of MIPs and nonimprinted polymers were investigated. The results showed that MIPs enable the selective extraction of pirimiphos-methyl successfully from water sample, and demonstrated the potential of MISPE for selective and cost-effective sample pretreatment.

Introduction

Organophosphorus pesticides (OPPs) have often been employed in farmland cultivation over the last several decades and are still continuously used in modern agricultural systems [START_REF] Liu | Analysis of bacteria degradation products of methyl parathion by liquid chromatography/electrospray time-of-flight mass spectrometry and gas chromatography/mass spectrometry[END_REF] . These OPPs exhibit acute or chronic toxicity to human, environment and the biota thus emphasizing the need for efficient analytical procedures to monitor potential risks. Most OPPs are easily analyzed by GC and HPLC. Generally, the trace analysis needs a pretreatment step in order to reduce the matrix interference and enrich the analyte. This is often performed by solid-phase extraction (SPE) [START_REF] Brito | Determination of pesticide residues in coconut water by liquid-liquid extraction and gas chromatography with electron-capture plus thermionic specific detection and solid-phase extraction and high-performance liquid chromatography with ultraviolet detection[END_REF][START_REF] Ismail | Determination of cis and trans isomers of monocrotophos in technical products by reversed-phase column liquid chromatography[END_REF][START_REF] Mullett | Determination of theophylline in serum by molecularly imprinted solid-phase extraction with pulsed elution[END_REF] .

Molecular imprinting is a versatile technique that creates molecular assemblies of desired chemical structures and properties [START_REF] Hong | A disposable microfluidic biochip with onchip molecularly imprinted biosensors for optical detection of anesthetic propofol[END_REF] . During last decade, molecularly imprinted polymers (MIPs) have demonstrated a great potential as selective sorbents and have been widely used for the clean-up of samples in SPE processes [START_REF] Pichon | Affinity separations on molecularly imprinted polymers with special emphasis on solid-phase extraction[END_REF][START_REF] Caro | Application of molecularly imprinted polymers to solid-phase extraction of compounds from environmental and biological samples[END_REF][START_REF] Andersson | Molecular imprinting for drug bioanalysis[END_REF] , namely molecularly imprinted solid-phase extraction (MISPE). The ongoing research has proven that MIPs can be efficiently used in this field [START_REF] Ramstrom | Food analyses using molecularly imprinted polymers[END_REF][START_REF] Bereczki | Determination of phenytoin in plasma by molecularly imprinted solid-phase extraction[END_REF] .

In this article, we reported the synthesized method of acrylic-based MIPs following the non-covalent approach and the selective use of MISPE technique for the analysis of organophosphorus pesticides.

2

Materials and methods

Materials

Pirimiphos-methyl (99.7%), methylnitrophos (99.2%) and malathion (97.2%) were purchased from J&K Scientific (Beijing, China). Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were purchased from Sigma. The initiator 2,2'-azobisisobutyronitrile (AIBN) was purchased from Shanghai Chemical Plant (Shanghai, China). All solvents of analytical grade were purchased from Beijing Chemical Reagent (Beijing, China). All syntheses were carried out using distilleddeionized water (18.2 MΩ.cm, PALL system). All solutions were filtered through a 0.45μm membrane from Millipore before use.

Polymer preparation

The template pirimiphos-methyl (0.305g, 1mM) and functional monomer MAA (0.344g, 4mM) were dissolved in 5.6mL dichloromethane in a 40-mL glass tube with slightly shaking for 6h. To this solution, cross-linker EGDMA (3.964g, 20mM) and AIBN (40mg, 0.24mM) were added in steps. Then, the mixture was deoxygenated with nitrogen for 15min, followed by degasification under vacuum for 5min and sealed. The polymerization was carried out by heating the mixture in a 60℃ water bath for 36h. The obtained polymer was ground to fine powders and sieved to obtain 60-70μm particles. These particles were extracted in a Soxhlet for 24h with methanolacetic acid (9:1, v/v) until no residue of template was found in the rinses.

The corresponding non-imprinted polymers (NIPs) for comparison experiments were prepared in the same manner but without addition of template.

MISPE protocol

Two hundred milligrams of the cleaned-up MIPs (or NIPs) were put into a 10mL vial and incubated with methanol, standing at ambient temperature with occasional shaking for 24h. Then the slurry was transferred into a 3mL polypropylene SPE cartridge and stood for 30min. After that, polyethylene frit was carefully put onto the polymer to stabilize the sorbents. MIPs of the size 60-70μm proved to be an acceptable compromise between homogeneity and permeability of SPE cartridge. Prior to use, the MIPs (or NIPs) SPE-cartridges were conditioned by washing with 10mL methanol-acetic acid (9:1, v/v) and 2mL methanol, followed by 2mL water. For the MISPE process, standard solution (a mixture of pirimiphos-methyl, methylnitrophos and malathion, 1μg/mL) and a spiked water sample were loaded onto the MISPE cartridges at a flow rate of 0.4mL/min respectively. And then the SPE cartridges were washed with 2mL dichloromethane/acetonitrile (95:5, v/v) and eluted with 2mL dichloromethane/methanol (90:10, v/v) by steps. The eluate was immediately dried under a stream of nitrogen, and the residue was dissolved in 1mL dichloromethane for GC-MS analysis.

GC-MS assay

The assay was conducted by Shimadzu GC-MS QP2010 Plus. The analyses were carried out on a gas chromatograph fitted with a HP-5 MS capillary column (30 m×0.25mm id; 0.25μm film thickness). Analytical gas chromatography conditions were as follows: injector temperature 230℃; oven temperature held at 120℃ for 5 min, then programmed to increase from 120℃ to 150℃ at a rate of 5℃/min and held for 7min; carrier gas, helium at a flow rate of 1mL/min; Mass spectrometer conditions: ionization mode with EI, electron energy 70eV, ion source temperature 230℃, interface temperature 220℃. Instrument operation and data processing was done through the LabSolutions (version 2.50) software.

Results and discussion

Synthesis of polymer

The choice of polymerisation solvent is the key point of the adduct formation and the promotion of the imprinting efficiency [START_REF] O'shannessy | Molecular imprinting of amino-acid derivatives at low-temperature (0-degrees-C) using photolytic homolysis of azobisnitriles[END_REF] . Dichloromethane is one of the most widely used solvents, since it satisfactorily dissolves all the reaction components and does not suppresses hydrogen bonding. We speculate that the use of dichloromethane can enhance the unspecific binding of analyte to the crosslinker. In addition, the nature of the crosslinker is another key factor of the polymer specificity [START_REF] Wulff | Enzyme-analogue built polymers. 22. Influence of the nature of the crosslinking agent on the performance of imprinted polymers in racemic resolution[END_REF] . The reactivity of the crosslinker should be similar to that of the functional monomer. And the mole ratios of crosslinker to functional monomer are also important [START_REF] Ansell | Molecularly imprinted polymers by suspension polymerization in perfluorocarbon liquids, with emphasis on the influence of the porogenic solvent[END_REF] . Generally, hydrogen bonding is dependent on both distance and direction between monomers and templates. EGDMA as the shortest crosslinker led to the highest selectivity in the polymer [START_REF] Wulff | Preparation of chromatographicsorbents with chiral cavities for racemic resolution[END_REF] .

Specificity of polymer

One merit of MISPE is that the polymer sorbents have good selectivity for the template molecule. To evaluate the specificity of this kind of SPE materials, the molecular recognition properties of three different OPPs (pirimiphos-methyl, methylnitrophos, malathion) was investigated. A total of 1.0mL of a mixture of 1μg/mL of each organophosphorus was applied to the MIP and blank polymer cartridges, and then the compounds in both the washing and elution fractions were analyzed by GC-MS. Fig. 1 showed the chromatograms of OPPs in standard solution, washing solutions, and elution fractions. It can be seen that almost all of the OPPs were completely removed from the blank column after the washing step. However, a different result was observed for the MISPE cartridge. Pirimiphos-methyl, the template molecular, was still totally retained on the MISPE column after the washing step. The recovery of pirimiphos-methyl was higher than 80%. In addition, the left OPPs were not retained on the MISPE column. In other words, they cannot be recognized by the MIPs and were completely separated from the target analyte. These results showed that the MIP exhibited highly selective binding affinity for pirimiphos-methyl and no binding for the left OPPs. Although there is only slight difference between the structures of those three OPPs, this further explains that the imprinting is not only based on the interaction of the functional groups of the analyte but also based on the combined effect of shape and size complementarily [START_REF] Lu | Molecular recognition through the exact placement of functional groups on non-covalent molecularly imprinted polymers[END_REF] . The recovery of three OPPs (Table 1) showed that the MIP cartridge could be proved to be a powerful tool for the enrichment of pirimiphos-methyl.

Determination of pirimiphos-methyl in spiked water sample

To demonstrate the applicability of reliability of this method for environmental application, real environmental water sample was selected and analyzed. Tap water was spiked with pirimiphos-methyl at the 1μg/mL concentration level and was preconcentrated by MISPE. The recovery and reproducibility of this method were calculated and summarized in Table 1. As expected, for analysis of pirimiphos-methyl in the water sample, the analyte recovery was higher than 80%.

Conclusion

In this report, we discussed the utility of molecular imprinting technology for the organophosphorus pesticides detection. MIPs selective for pirimiphos-methyl was prepared and applied as the material for SPE in off-line separations. The polymer showed well affinity and selectivity to pirimiphos-methyl. And the MISPE proved to be an effective tool for the enrichment of pirimiphos-methyl from water sample. For organophosphorus pesticides, the MISPE approach provided simpler methodology and significant increases in selectivity relative to the conventional methods. And we feel that this approach will be a useful analytical tool for analyzing complex samples, especially in performing the initial screening of libraries against poorly characterized receptors.

Fig. 1 .

 1 Fig. 1. Chromatograms obtained by off-line SPE of 1.0mL of a mixture of 1μg/mL of each OPP. (a) standard solution; (b) NIP, washing fraction; (c) NIP, elution fraction; (d) MIP, elution fraction; (e) water sample. (1) pirimiphos-methyl; (2) methylnitrophos; (3) malathion. Wash step: 2mL dichloromethane/acetonitrile (95:5, v/v). Elution step: 2mL dichloromethane/methanol (90:10, v/v).

Table 1 .

 1 Recoveries of three OPPs after loading of 1.0mL of 1μg/mL of each OPP onto the

	SPE cartridges (n=3)
	Analyte	NIP(%±SD) Washing Elution Elution Tap water MIP(%±SD)
	Pirimiphos-methyl 97.6±2.5	0	83.2±3.1 80.1±2.3
	Methylnitrophos	96.1±3.9	0	0	0
	Malathion	99.3±2.6	0	0	0

Corresponding author. Tel: +86 10 51503031; fax: +86 10 51503406. E-mail: panlg@nercita.org.cn

Acknowledgments. This work was supported by the National High Technology Research and Development Program 863 (2010AA10Z403, 2007AA10Z202) and Beijing Municipal Science and Technology Commission Program (Z09090501040901).


Hu Haiyan
email: huhaiyan@mail.caas.net.cn

Su Xiaolu

A General Agriculture Mobile Service Platform

Keywords: Mobile service, Mobile platform, SMS protocol, MMS protocol, Mobile protocol

Most of today's information services on the web are designed for PC users. There are few services fit to be accessed by mobile devices. In the countryside of China, most of the mobile phone users can not access the Internet. For this reason, We developed General Agriculture Mobile Service Platform.

The Platform is designed to make these information services fit to be accessed by mobile users, and to make those mobile phone users can use these services without Internet connection. To achieve that, a descriptive language is designed to describe the services' inputs and outputs, used to passing requests and responses between the platform and the mobile client software. With those descriptions, client software can generate user interface on the client mobile device. Using that interface, user can manipulate service. The communication between client side and the platform can be carried by SMS, MMS as well as TCP, so that the devices which don't have Internet connection can access those services.

Introduction

Do not have internet connection, one can only be reached by mobile specific communication protocol. Most of the users of cheap mobile devices, as their devices has so limited operability and is not fit for using internet application, will simply chose to have none internet connection. Their mobile device supports only phone call and SMS. To make our service being reachable to these users, a SMS/MMS based communication protocol is developed to handle communication via SMS and MMS, and an independent mobile communication protocol layer is added to the platform. With SMS based communication, the platform can be reached by 100% of mobile users.

The processing capacity, presentability, and operability of mobile devices are limited, complicate data presentation and complicate operation can not be done on mobile device. Standard web based user interface is not fit for mobile users. Between mobile devices, capacity of display and operate vary so greatly that can not design a standard client user interface to fit all types of devices.

On mobile devices, software installation and running is limited, complicate software functions is not applicable. Client software must adaptable to all these limitation.

Platform design

Client/Server architecture

Mobile terminal may not support Internet connection. Client/server is the only applicable architecture to leave room for the special designed mobile communication protocol.

Mobile protocol layer

Seal mobile communication protocol to an independent layer, simplified both the client and the server software design, and made maintenance and upgrading easy.

Web Service composition

Server composes available web services into functions which fit for mobile user. The client software can only have a set of very limited functions, so that it can not call complicate services by itself, services must be packaged by server firstly, to make them fit for calling by client software.

User interface auto generation

Based on the capacity of the current mobile device, client software generates user interfaces for each service according to its service description. Each function offered has a formal description, which includes descriptions to all parameters that function needs. All functions consists the service list, which is the data source of service choice list on the client side. With those descriptions, client software can generate user interface to launch calling to those functions, and to handle the returned data.

Command pattern

Client side software launch calling to server side functions by translation user inputs into commands and sending them to server. The server translates each command to the actual calling to launch the corresponding function, and then package the returned data as response to that command.

Then client side handles the returned response to generate user interface to display it.

Information leaning based on personal knowledge and demand.

Server traces each user's access records, calculates his possible knowledge structure and interest point. With that information, server can lean the information returned by remove those out of the scope of user's knowledge and those out of user's interest. This function can be switched off manually.

Implementations

SMS and MMS based communication protocol

A single SMS message can carry only 140 byte information, equal to 140 ASCII characters or 70 double byte symbols. This sets the up limit of a single data package. Such a package size is too small to carry information (compared to other communication protocols, such as Ethernet's 1544 byte package).

To transmit data over such a tiny package, the first thing must do is to make the package structure as simple as possible to leave room for data; the second thing must do is to make data can be carried by multiple packages, that means data must be dissembled at transmit end and assembled at receive end, some kind of sequence control must be introduced to assure recover data in original sequence [1.2].

There are 3 tasks of the protocol: establish session and offers the current endpoint context to server submit service request and receive returned data end session Figure 1 : A typical session sequence Figure 1 shows a typical session, includes session starting and ending, and some service requests/responses. Corresponding to these 3 tasks, 2 types of packages are needed, one is used to establish and end sessions, the other is used to carry service requests and responses. Every package is a SMS message, to keep the session traceable and according the sequence of sending and receiving, each package has a serial number. Because the system also allow user edit and send SMS message manually, and those manually edited message should not be expected to have correct serial number like the automatic generated ones, so if a package do not have serial number, it will be handled as is, without premising in correct sequence. The packages with no serial number can not be used to establish or end session, update contexts, choose service to entry, or to do all platform specific job, but can be used to carry service requests, whether it is acceptable is leaved to the service it requests.

Serial number should always stay at the beginning 4 character, starts with '#', followed by 3 digits, that means the largest serial number is 999. Statistically, most of user sessions won't use so many packages to make serial number overflow. If overflow really occurs, it still doesn't matter, serial number simply start from 0 again, we simply regards serial 000 is larger than 999, there will be almost zero chance to disturb communication sequence. If a package is sent more than once (often caused by mobile network provider), the duplicated ones will have the same sequence number, if received more than 1 packages which have the same serial number, the package latest received will be kept and the earlier ones will be simply discarded. Unlike most communication protocols, there is no ACK package, the reliability of communication is assured by SMS itself. If ACK is really needed, ACK words can be put directly after the serial number, each ACK word starts with the prefix 'R', followed by 3 digits represents the replied package's serial number, nothing should be put between each pair of neighboring ACK words and between serial number and ACK words. A package with ACK words may look like this (Figure 2 The package's length is not fixed. And no method is designed to check its length, assurance of the integrity of package is leave to SMS.

Voice service

The mobile communication protocol is not fit for transmit long text, and the mobile device itself is often not fit for read much text. If large text needed to be delivered to user, voice is a reasonable choice.

Along with SMS, voice is the only other communication method which all mobile device must supports. Regarding that voice can not be formalized, complicate interaction can not be carried by voice service, the only job fit for voice is deliver text.

The voice service offered by platform is quite simple. Every user by default will own a voice box, at most 9 voice messages can stored in it, each of them has a title and content. If the box is already full, coming of new message will overwrites the oldest one without warning or confirmation. Client software offers a user interface to manage user's voice box, user can see message title list and delete message through this interface, but can not get message contents. To get contents, user must call the number of voice service, and then voice service will read out each message title, starts with a serial number, user push the digit button of the serial number will make voice service read the message with that number to user.

Client software developed with J2ME

Simply say, client software's job is to translate user's operations into calling to services, server finish those calling and return data to client, then client generate an user interface to display the returned data as while as to prepare user's further operation which using some of those data as input.

The first, client must be able to communicate with server, so it must have mobile communication protocol layer, client software can detect mobile device's capability of communication automatically, and decide the most suitable communication method, user can also manually set communication method.

Client software must very flexible, and can adapt to all kinds of limits of all different mobile devices.

All user interfaces can adjust automatically to fit for the device's capacity. Most of the user interfaces are generated automatically, so that services can be added dynamically, without updating the client software. There are some basic operation interfaces which are not automatically generated, they are client software configuration screen, user profile management screen, voice box management screen, service selection screen. After entering a service, all user interfaces are generated based on the service description and function list of the service. To minimize communication, service description is not strictly formalized, the grammar is very simply, many defaults are automatically applied while no declaration presents. For example, the only allowed data type is number and string, if a piece of data comply with any digital format, it will be regard as digits, otherwise it will be look as string, so that the extra data for data type is not needed [START_REF] Qusay | Getting Started With the MIDP 2.0 Gam API[END_REF].

The 3 layered server end software

Server end is consisted by 3 layers, mobile protocol layer, basic platform service layer, and service composition layer.

At server side there is a counterpart mobile protocol layer handling communications via mobile protocol, but the implementation of this layer is not the same as client side. Unlike the client, server is not naturally support mobile communications; it must connect to some mobile capable devices to extend its mobile capacity. And then, the protocol layer divided into 2 parts, running on the server and its mobile extension devises respectively.

Basic platform service provides basic functions such as user profile management, user activity tracing, personalized sorting and filtering, voice box management, and service management.

The core function of the platform is to manage services, these services are described in OWL-S documents, and ready to be called by the client side. Each service has a name and a description. User can regard each service as an entry point to access a certain kind of resources, by calling that service, user can access the resources the service provides. A simplest service can only provide a resource list and detail data of each resource. In more complicate occasion, category and search are provided to assist user to locate resource mo efficiently. If resources can be created, changed or removed by user, the service should also include CRUD functions. Beside these, a service should not include any unnecessary function. This limit of simplicity on service simplified user interface generation. If a service originally provides more than this, it should be simplified first, before added to platform [START_REF] Richardson | RESTful Web Services[END_REF].

The platform provides a general propose filtering and sorting function based on user's personal knowledge structure and current interest point. An OWL document is maintained for each user to records the knowledge the user may have. User's knowledge is inferred from user's activities, so do to user's current interest point. Personalization is implemented by another independent software package, and further discussion on personalization is beyond the scope of this paper. What make sense to the platform is that personalization helps significantly reducing the communicated information, and interactive rounds.

Web service composition with OWL-S

The server does not care about where the OWL-S description comes from, and whether or not it is correct or effective, those jobs are handled by other systems. The server just use these OWL-S descriptions, call web services according to them, if something failed, a standard error message will be shown.

Services is added into platform through service management user interface, this is a web based UI and can not be accessed by common users. Each service has a group of processes, OWL-S describes how to launch these processes. At client side, while entering a service, there is a main menu shown to user, lists all the processes the service had. By select the menu item, client side sends command which at server side launches the corresponding process. At every step of the process triggered, if some parameter is not available from environment and previous outputs, that means user input is needed, at that time, a user interface to input those data is generated. Thanks to the limit of simplicity, all these processes are simple, only sequence flow can appear. So that the platform need to support only sequence control flow, and can regardless loops or branches the OWL-S processes may have [5.6].

Conclusions

By introducing mobile communication protocol, make the platform can cover 100% of mobile users.

By introducing web service composition, make it easier to enrich service contents available to mobile users. All these will attract more mobile users and make the mobile technology valuable to agriculture production.

Figure 2 :

 2 Figure 2 : The response package structure

Acknowledgement

The research was supported by the national 863 project, Mobile intelligence service for agricultural scientific & technical information (project code 2007AA10Z236) and special fund of basic commonweal research institute project of information institute of CAAS.


Xiangbo Han

Zhanli Liu

Farmland Irrigation Remote Monitoring System Based on Configuration Software and Multiple Serial Port Communication

Keywords: Multi serial port communication, Configuration software, Farmland irrigation

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

With the rapid development of society and economy, farmland irrigation demands higher reliability and quality of water supply. Advancement of computer and automation technology makes the research of higher performance water supply system possible. Now most water supply systems have a lot of limitation, for example, little information acquisition, low manage and transfer. Information exchange among system and environment or equipments is difficult to achieve. It restricts greatly information acquisition and automation of corporation. Therefore, it plays an important realistic role in decreasing energy consumption and sharing information that researching the high performance and network monitoring system of constantpressure water supply [START_REF] Wu | Development of on-board data collect ion system based on Fame View and PLC[END_REF][START_REF] An | The application of ABB PLC in the process monitoring and control for limekiln production[END_REF] . Based on configuration software, the monitoring system of constant-pressure water supply is developed by means of multiports, which satisfies requirement of corporation on water supply automation, and provides water supply corporation with a new resolution in order to realize unmanned watch-keeping, energy conservation and safety.

*Corresponding author. Email: zhanliliu2009@yahoo.cn 2

System constitution

Fig. 1 The composition of farmland irrigation monitoring system

Water supply station has four wells, the first and third well is 120 meter deep, the second and fourth is 80 meter deep, the fifth is spare. There are four dive pumps of deep well, and one is spare among them. Three pumps can fit together freely, and spare pump can operate manually. The pressure of exit is 0.33Mpa constantly (0-1Mpa adjustably). Means of start-up is autoconnected serial portping voltage.

In this paper a new water supply surveillance system is developed, including IPC (industrial personal computer), PLC, transducer, intelligent module, and etc. Control subsystem is composed of advantech IPC 610 IPC, CPM2A programmable controller, SAMCIO-VM05 special water supply transducer. Signal acquisition subsystem is composed of ADAM -4017, water level transmitter, Flow transmitter, current transmitter, voltage transmitter, and etc. Advantech intelligent module ADAM-4017 is used for analog signals, for example, voltage acquisition, current acquisition, and etc. ADAM-4017 is intelligent sensor interface module of built-in Microprocessor. It can be connected with serial port of IPC by RS232/RS485 interface module. Operator can observe manually. Each digital panel meter is divided into one signal, which is sent to intelligent module ADAM-4017 in computer ground loop. Consequently computer can collect data.

Water supply volume and pressure of water supply system is instantaneous with water use need. Water pumps assume a lot if run according to rated flow and rated pressure, pressure fluctuates with flow. By pressure sensor of equipment exit the system transfers flow and pressure signal into standard electric signal, then send to PLC and ADAM-4017.By comparison, amplification, differential, integral, optimal control parameter is transferred into transducer, so that rotate speed of water pump can run according to practical water use and given pressure. We can achieve the aim to save energy efficiently, supply water with constant pressure and adjustable flow. In system bias removal, PID regulation can assure bias is zero so that system attains stability. Closed loop control system is composed of PLC, transducer, water pump and pressure sensor, and can carry out constant-pressure water supply (Fig. 1).

Communication mode

In monitoring system, IPC and PLC, transducer, analog collector module communicate through serial ports, as is shown in fig. 1. Serial port extention adopts Advantech PCL849A card, affording four RS-232 serial ports. They can assure many equipments run at the same time, and afford interfaces for equipment replacement and upgrade. PCL849A card needs to set the site of extended serial port, discontinuity of use, communication speed, type of operating system and etc, be completed by jump wires on board card. While setting site of extended serial port and discontinuity, the paper avoids used sites and interrupt numbers in operating system. We can carry out communication with spot control equipments expediently by KingView device driver. KingView serial type logical device is its built-in serial port driver's logical name, corresponding with the actual devices connected to the computer serial port and supplying for KingView by the dynamic link library.

Configuration design

In software, making use of configuration king KingView as engine configuration, interface of monitoring software is friendly, easily operational. Graph visualization is colorful, and circulation of spot equipments is shown dynamically in real time [START_REF] Zhou | Design of a configurable software based on VC ++ programming language in the integration of intelligent building system[END_REF][START_REF] Sun | Design of coal mine monitoring and controlling configuration software based on ActiveX[END_REF][START_REF] Liang | Design and development of graph system in SFC configuration software[END_REF]. In automation monitoring, the software can show technique process graph, draw water level curve of water tower and running curve of water-lift engine at any moment and change cure of water pressure. It can reflect dynamically the curve change trend of checking parameters, collect spot data and states in real time and gather data. Report forms function of software can attain data print, management, sharing of longdistance data.

In network, the monitoring software can run based on TCP/IP, so as to network communication from hypogynous computer to epistatic computer and long-distance server. As a customer server mode, server of the configuration system can set IO server, historical data server, alarming server, registering server, WEB server and etc according to system requirement. While a site of system is specified as a server, it can be other kind of server, and customer computer of other site server. The flexible network structure increases whole capacity of system and system function. WEB server using HTML and other technology equipment run the screen, a variety of dynamic curve and the report to generate dynamic web pages and realize remote network monitoring [START_REF] Pang | Weather information issuance system based on web service[END_REF] .

  It can be controlled by long-distance, communicating through 485 cable. Spot check data such level, flux, voltage, current and etc. are converted to standard signal (from 4 to 20mA) by sensor and transmitter, then transferred to central control cabinet in control house, then sent to digital panel meters through isolation module circuit.


Ying Yang

Bo Peng

Jianqin Wang

A System for Detection and Recognition of Pests in Stored-grain based on Video Analysis

Keywords: video analysis, pest detection, pest recognition, store grain

This paper presents a system for detection and recognition of pests in stored-grain based on video analysis. Unlike current systems which conduct analysis of static images, the proposed system uses video data captured by camera and performs video analysis to detect and recognize pests in grain. By using video data instead of static images, techniques such as motion estimation and multiple-frame verification are used to locate, count and recognize pests. Compared to systems based on image processing, the proposed system is more robust to moving pests and avoids missing and re-counting of moving pests. Furthermore, by analyzing motion of pests in video, the system can only count living pests and ignore dead ones, which are recommended by national standard of grain quality and cannot be achieved by current systems based on static image processing.

Introduction

It is well known that pests inflict great damage to stored grain. For instance, in China, pests in grain cause loss of more than one billion Yuan every year. To avoid damaging to stored grain, it is vital to detect, recognize, and count pests in stored grain, since these operations offer information such as pest species and pest density for further measurements.

In earlier research efforts, pests are detected, recognized and counted manually [1][2]. For these methods, the results depended on environments and human operation, which make the methods unreliable. Other researchers try to detect pests automatically using near infrared spectrum or X-ray scanning [3][4]. These methods can yield good results, but they are of low efficiency and require expensive devices. These days, methods based on machine vision and computer image processing become the most popular method due to their low cost, high efficiency and good performance [5][START_REF] Qiu | Hareware Design of an Intelligent Detection System for Stored-grain Pests based on Machine Vision[END_REF][START_REF] Daoyin | Software Design of an Intelligent Detection System for Stored-grain Pests based on Machine Vision[END_REF][START_REF] Zhou | Application of wavelet analysis of restraining the noise and edge detection of pest image in stored grain[END_REF][START_REF] Zhou | Research on Fuzzy Detection Method of Pest's Image in Stored Grain Based on Machine Vision[END_REF][START_REF] Zhang | Identification and Classification of Grain Pest Based on Digital Image Processing Technique[END_REF][START_REF] Tong Zhen | Research of Grain Pests Detection and Classification Based on SVM[END_REF][START_REF] Lian | Detection of Pests in Stored-grain based on Image Recognition[END_REF][START_REF] I Y Zayas | Detection of insects in bulk wheat samples with machine vision[END_REF][START_REF] Ridgway | Imaging for the high-speed detection of pest insects and other contaminants in cereal grain in transit[END_REF]. These methods usually analyze images of grain taken by a camera to detect pests and use classifiers such as Neural Network or Support Vector Machine to recognize pest species. There are two major problems of these methods: first, since only one or few static images are processed, noises in images and moving pests may cause detection errors; secondly, it is impossible to decide whether the pests detected are living in static images, while only living pest density are considered in national standard of grain quality since only living pests can cause damages.

To solve the problems of current machine-vision-based systems, this paper presents a system for detection and recognition of pests in stored-grain based on video analysis. The system uses video data captured by a camera and performs video analysis to detect and recognize pests in grain. By using video data instead of static images, techniques such as motion estimation and multiple-frame verification are used to locate, count and recognize pests. The proposed system is more robust to moving pests and avoids missing and re-counting of moving pests. Furthermore, by analyzing motion of pests in video, the system can only count living pests and ignore dead ones. As shown in Fig. 1, the proposed system consists of two subsystems: video collection subsystem and video processing system. The two systems will be detailed in Section 2 and Section 3.

Video Collection Subsystem

The video collection subsystem is used to capture video of stored-grain. It is mainly a hardware subsystem similar to that proposed in [START_REF] Qiu | Hareware Design of an Intelligent Detection System for Stored-grain Pests based on Machine Vision[END_REF].

As shown in Fig. 1, the video collection is composed of four major components: grain sampling device, grain conveying device, illumination device and video capture device. The grain sampling device is used to take samples of stored grain. The device works like a pump and sucks grain though pipes to the conveying device. The conveying device is a conveyer belt moving at constant speed. The grain is placed of single layer on the belt, which makes all pests in grain can appear in the video. The illumination device is a LED light which makes sure the video captured in good and constant illumination condition. The video capture device consists of a CCD camera and video capture card. The device is connected to a computer through USB port.

When the device is running, video of grain on the conveyer belt is captured and transferred into computer memory at real time.

The main difference between the proposed video collection subsystem and current image-based systems (such as the system in [START_REF] Qiu | Hareware Design of an Intelligent Detection System for Stored-grain Pests based on Machine Vision[END_REF]) is that the proposed system takes video of grain instead of static images. Unlike current systems which take every image within a short interval (0.6 second in [START_REF] Qiu | Hareware Design of an Intelligent Detection System for Stored-grain Pests based on Machine Vision[END_REF]), our system takes continuous video at speed of 25 frames per second. The video is transferred and stored into computer memory and disk for further processing in the video processing subsystem.

Video Processing Subsystem

The video processing subsystem is a software system running on a computer. It receives video signal captured by the video collection subsystem as input and performs video analysis to detect, count and recognize pests in the video.

Before video analysis, the continuous video signal is first segmented into video segments. The length of segment depends on moving speed of the conveyer belt. In our implementation, the segment length is set as 2 seconds.

As shown in Fig. 1, the video processing procedure includes 3 stages: pest detection, living pest counting and pest recognition, which correspond to the three major modules of the video processing subsystem.

Pest Detection Module

In current systems based on image processing, since only one static image is processed, detection errors may be caused by noise, and miss or re-counting may be caused by motion of pests. In the proposed system, a segment of frames in video is used instead of a single image, so verification across multiple frames can be performed to avoid missing and re-counting caused by noise or pest motion.

Before multi-frame verification, pests are segmented in each frame of the input video: First, the image is processed using image sharpen to increase the difference between pest areas and the background. Then, pest areas are segmented from background using thresholds obtained by K-means clustering of the pixels in the image. Finally, more accurate areas of pests are obtained by morphological operations.

After obtaining pest areas in each frame, multi-frame verification is performed using a neighbor-searching method. For each pest area in each frame, the image area around the pest area is divided into multiple blocks. For the prior and next frame, searching of pests is performed in the neighbor blocks. If pest areas exist, similarity is calculated between pest areas in current frame and in adjacent frames. Finally, decision is made of whether the pest area in current frame is a false detection by thresholding the similarity. An illustration is given in Fig. 2. It can be seen that by using multi-frame verification, errors caused by noise or pest motion can be avoided. Therefore, better detection results can be obtained using the proposed system.

Living Pest Counting Module

As motioned above, in current system based on image processing, it is difficult to only count living pests and ignore dead ones since only static images are processed. In the proposed video-based system, a segment of video is processed. Therefore, living pests can be detected by analyzing their motion in the video. Since the grain on the conveyer belt is moving, motion of living pests can not be detected simply by using difference of frames. Therefore, the aim of living pest detection based on video analysis is to detect local motion of living pests within global motion of grain in the video.

In the living pest counting module, global motion estimation is performed to obtain parameters of motion between grain and the camera. In our work, a six-parameter affine model is used: if the 2D coordinates of one point on an object in continuous frames are ( , )

x y and ( ', ')

x y , the affine model of six parameters is

1 2 3 4 5 6
, x a x a y a y a x a y a

′ ′ = + + = + + (1)
where 1 2 6 , ,... a a a are parameters related to the camera. In our work, these parameters are estimated by global motion estimation of feature points which may be fix points marked on the conveyer belt. When global motion parameters are estimated, local motion of pest areas can be detected across multiple frames, and pests without motion are classified as dead ones.

When living pests are detected in each video segment, the count of living pest will accumulate to give total count of living pests.

Pests Recognition Module

The aim of pest recognition is to recognize species of pests. In current systems based on image processing, recognition errors may be caused by noise or override between grain and pest. In the pest recognition module of the proposed system based on video analysis, a multi-frame verification technique is also utilized to achieve better performance.

For each frame in the video segment, features including gray value, area, circumference, texture are extracted for pest areas recognition. These features are input into a SVM classifier to recognize the specie of the pest. The SVM classifier is trained with samples of pests using the same image features. The classification result of SVM is represented as probabilities of each species.

After getting specie-probabilities of each frame, multi-frame verification is performed by calculating the average probability value of each specie and choosing the one with maximum average probability as final recognition result.

Conclusions

This paper presents a system for detection and recognition of pests in stored-grain based on video analysis. While current systems conduct analysis of static images, the proposed system performs video analysis to achieve better performance. The system consists of video collection and video processing subsystems. In the video processing subsystem, techniques such as motion estimation and multiple-frame verification are used to locate, count and recognize pests. As to our knowledge, the system proposed in this paper is the first system which performs video analysis for pest detection and recognition in stored grain. Compared to systems based on image processing, the proposed system is more robust to moving pests and avoids missing and re-counting of moving pests. Furthermore, the system can only count living pests and ignore dead ones, which is recommended by national standard of grain quality and cannot be achieved by current systems based on image processing.

Fig. 1 .

 1 Fig. 1. Architecture of the proposed system.

Fig. 2 .

 2 Fig. 2. Illustration of multi-frame verification.