Weiming Cai

Huinong He

Songming Zhu

An Audio Generator System for Experimental Studies on Acoustic Biology

Keywords: Audio Generator System, Acoustic Biology, ARM+DSP+FPGA, DDFS, Sound Wave

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

Introduction

Audible sound, as a sort of sound waves, whose frequency is between 20Hz and 20,000Hz, widely exists in natural environment. In recent years, there have been studies relating to sound and the growth and health of plants or animals, including human beings [START_REF] Chabris | Prelude or requiem for the "Mozart effect[END_REF][START_REF] Creath | Measuring Effects of Music, Noise, and Healing Energy Using a Seed Germination Bioassay[END_REF][START_REF] Collins | The effect of sound on the growth of plants[END_REF]. It has been hypothesized that sound increases growth in plants, and some companies even use a growth system that incorporates sound to try to increase growth. Studies have been done on the use of music to improve crop yield and quality in plants such as tomato plants [START_REF] Hou | Applied studies of Plant Meridien System: I. The Effect of Agriwave Technology on Yield and Quality of Tomato[END_REF], barley [START_REF] Xiao | Vegetables and music[END_REF], and vegetables [START_REF] Hou | Application of acoustic frequency technology to protected vegetable production[END_REF]; [START_REF] Hou | Application of acoustic frequency technology to protected vegetable production[END_REF] used audible sound waves to stimulate more than 50 different crops, and achieved remarkable effects. This field of science is known as acoustic biology. Up to now, why plants or animals are subjected to sound waves in order to improve crop yield, quality, and animal health is still unknown. Not *Corresponding author. E-mail: zhusm@zju.edu.cn much study was done in this area, as there was a lack of precise instruments to facilitate propagation growth studies in the acoustic biology field as well as a lack of proven scientific theories in this area.

Direct digital frequency synthesis (DDFS) is a method of producing an analog arbitrary waveform [START_REF] Jeng | High-Performance DDFS Design Using the Equi-Section Division Method[END_REF][START_REF] Chen | A Direct Digital Frequency Synthesizer Based on a New Form of Polynomial Approximations[END_REF]. The operations within DDFS devices are primarily digital; it can offer faster switching between output frequencies, operation over a broader spectrum of frequencies and better frequency resolution than traditional ways [START_REF] Shmelev | A two-channel multi-tone computer audio-frequency generator[END_REF][START_REF] Shen | Picosecond fast arbitrary waveform pulse generator[END_REF]. A practical DDFS system is often realized in hardware platform. ARM+DSP+FPGA is a new-type platform for complex system development, algorithm verification, prototype trialmanufacture, and prototype evaluation (e.g. multimedia processing system, digital communication system, and high performance instrument prototype development), and it haven't been used to design audio generator before, although it is ideal for us to perform high performance system verification and instrument development.

Therefore, in order to offer a scientific research instrument for the study of sound wave effect on propagation growth promotion in the field of acoustic biology and explore a new way in making high-performance audio generators, a new-type audio generator system based on ARM+DSP+FPGA and Technology of DDFS was proposed in the paper.

2

Principles and Methods

Technology of Direct Digital Frequency Synthesis (DDFS)

A basic Direct Digital Frequency Synthesizer consists of a phase accumulator, phaseto-amplitude converter (a Waveform Memory), a Digital-to-Analog Converter and filter as shown in Fig. 1.

Fig. 1. Block diagram of DDFS

The frequency of synthesized output depends on three variables: a reference-clock frequency F clk and a binary number programmed into the phase register (frequency setting word d), the length of accumulator k. When a sine signal is recorded in the waveform memory, the phase accumulator computes a phase (angle) address for the waveform memory, which outputs the digital value of amplitude (phase angle) to the DAC. The DAC, in turn, converts the number to a corresponding value of analog voltage or current. To generate a fixed-frequency sine wave, a constant value (the phase increment determined by the binary number d) is added to the phase accumulator with each clock cycle. When the phase increment is large, the phase accumulator will step quickly through the sine record in the waveform memory and thus generate a high frequency sine wave. When the phase increment is small, the phase accumulator will take many more steps, accordingly generating a slower waveform.

If F clk is the clock frequency, then the frequency of the output sine wave can be described as follows:

k clk out F d F 2 *  2 k-1 >d≥1 (1)
Where: F out is the output frequency of DDFS; d is the frequency setting word; n (in bits) is the length of the phase accumulator; F clk is the system clock frequency.

Equation ( 1) is known as the tuning equation of DDFS. Any change to the value of d results in immediate and phase-continuous changes in the output frequency. In a DDFS, no loop settling time is incurred as in the case of a PLL. As the output frequency is increased, the number of samples per cycle decreases. According to sampling theory, at least two samples per cycle are required to reconstruct the output waveform; the maximum fundamental output frequency of a DDFS is 2F clk . However, for practical applications, the output frequency is limited to somewhat less than that for improving the quality of the reconstructed waveform and permitting filtering on the output.

Audio Generator Based on ARM+DSP+FPGA and DDFS

An embedded development platform based on ARM, DSP, and FPGA was set up for the design of audio generator system. As shown in Fig. 2, the embedded development platform consists of a C6-Integra DSP+ARM Processor OMAP-L137, a Xilinx Spartan™-3A FPGA Platform--XC3S50A, a D/A converter CS4341, an A/D converter AK5350, sound sensor, User interface (LCD and Touch screen), Communication interface (USB and RS-232), and so on.

Fig. 2. Schematic diagram of embedded platform for audio generator design

The OMAP-L137 C6-Integra™ (Texas Instruments Incorporated, 2010) is a processor of low-power applications based on an ARM926EJ-S and a C674x DSP core, and it enables us to quickly bring to devices featuring robust operating systems support, rich user interfaces, and high processing performance through the maximum flexibility of fully integrated mixed processor solutions. The ARM926EJ-S is a 32-bit RISC processor core that performs 32-bit or 16-bit instructions and processes 32-bit, 16-bit, or 8-bit data, and the core uses pipelining so that all parts of the processor and memory system can operate continuously. The OMAP-L137 DSP core uses a twolevel cache-based architecture: the Level 1 program cache (L1P) is a 32KB direct mapped cache and the Level 1 data cache (L1D) is a 32KB 2-way set-associative cache; the Level 2 program cache (L2P) consists of a 256KB memory space that is shared between program and data space. L2 memory can be configured as mapped memory, cache, or combinations of the two. Although the DSP L2 is accessible by ARM and other hosts in the system, an additional 128KB RAM shared memory is available for use by other hosts without affecting DSP performance. In our design, the functions such as User interface, frequency setting control for the DDFS system, feedback analysis for output sound waves are mainly depend on the OMAP-L137 processor, which is one of the cores in the design of audio generator.

The Spartan-3A FPGA XC3S50A (Xilinx, 2007) is one of programmable chips with 1.4M system gates, and 502 I/Os, with density migration. The phase accumulator and phase to amplitude conversion of DDFS is realized through programming in the FPGA; the FPGA also was used to the data communications and external state control in our design.

The CS4341 is a complete stereo digital-to-analog system including digital interpolation, fourth-order Delta-Sigma digital-to-analog conversion, digital deemphasis and switched capacitor analog filtering. The advantages of this architecture include: ideal differential linearity, no distortion mechanisms due to resistor matching errors, no linearity drift over time and temperature and a high tolerance to clock jitter.

The CS4341 can accept data at audio sample rates from 4 kHz to 100 kHz. There is a filter in the inner of CS4341. So it is not necessary for us to design additional filter for the DDFS module.

The AK5385A is a 24 bit, 192 kHz sampling 2ch A/D converter for high-end audio system. The modulator in the AK5385A uses the Enhanced Dual Bit architecture and the AK5385A realizes high accuracy and low cost. The AK5385A performs 114dB dynamic range, which can meet the dynamic range from 0 dB to 110dB of our design requirement. By using a sound pressure sensor, the A/D converter and programming in the OMAP-L137 (the sound analysis are mainly made by the C674x DSP core), the feedback analysis network can be accomplished.

Results and Discussion

In order to see whether the accomplished audio generator system can satisfy the demand of studies of sound wave effect on propagation growth promotion, a series of tests were conducted. Fig. 3 is the time domain signal graph of sound wave detected by the feedback block of the accomplished audio generator system when a sine wave with frequency of 1000Hz was inputted from the User interface of the generator. The generator system can produce sound wave signals with frequencies range from 20Hz to 20,000Hz for the speaker.

Fig. 3. Time domain signal graph of 1000Hz sound wave

Natural sound such as cricket sound may have effect on propagation growth according to many studies [START_REF] Chabris | Prelude or requiem for the "Mozart effect[END_REF][START_REF] Creath | Measuring Effects of Music, Noise, and Healing Energy Using a Seed Germination Bioassay[END_REF][START_REF] Collins | The effect of sound on the growth of plants[END_REF][START_REF] Hou | Application of acoustic frequency technology to protected vegetable production[END_REF]. The generator can simulate the cricket or other insects' or birds' sound for the studies and the sound frequency can also be analyzed by the generator. Fig. 4 is the time domain signal graph of sound wave detected by the feedback block of the accomplished audio generator when cricket sound wave was inputted from the User interface of the generator.

Fig. 4. Time domain signal graph of cricket sound wave

Sound-level measurements offer a conventional way to measure sound but do not contain frequency information, making it difficult to compare different sounds effect in our research. Octave analysis filters the signal and measures the energy at the output to provide useful frequency information. With fractional-octave analysis, we can select a frequency resolution that is well adapted to the signal of interest. In a word, Octave analysis is a valuable tool for visual inspection and comparison during our researches. The new-type audio generator system offer octave analysis of output sound both for the output regulation and frequency information.

Some octave analysis was made by the generator system when the test work was conducted. The results can be seen in Figs. 5678.

Fig. 5 shows the octave analysis chart of background noise in our testing environment. The background noise is also a factor in the research on propagation growth. So it will give us deeper understanding on the grow environment and help to explore growth promotion secrets to analysis background noise. Fig. 5. The octave analysis chart of background noise Fig. 6 is the octave analysis chart of cricket sound. Through the octave analysis on cricket sound, we can find that frequencies around 4000Hz are main frequency components in cricket sound. This offers us a scientific way in study of insects' sound effect on propagation growth. Fig. 6. The octave analysis chart of cricket sound Fig. 7 shows the octave analysis chart of thrush sound. Through the octave analysis on thrush sound, it can be found that frequencies around 2000Hz are main frequency components in thrush sound. This offers us a scientific way in study of birds' sound effect on propagation growth. From the test results described above, It can be found that the new-type audio generator system designed in the study not only can produce varies kind of sound wave but also can monitor the sound output and make analysis of the sound wave in the experimental environment. When we make researches on sound wave effects of propagation growth promotion, it is very important to load a specific sound exactly and understand the environment sound characteristic. Therefore, the audio generator designed in the study will be a useful tool to studies in the field of acoustic biology.

Conclusions

A new-type audio generator system was designed for the study of sound wave effect on propagation growth promotion in the acoustic biology field. The generator system can produce varies kind of sound required in the study of acoustic biology, and it can also do octave analysis of the sound wave in the experiment environments for acoustic biology researchers.

Unlike most of traditional audio generator systems, the generator designed in this study is based on a new embedded development platform with the ARM+DSP+FPGA core and DDFS technology, which enable us to make feedback analysis networks for the output sound and generate arbitrary waveforms.

Fig. 7 .

 7 Fig. 7. The octave analysis chart of thrush sound Fig. 8 is the octave analysis chart of a slice of Mozart music (Allegro Molto).Through the octave analysis on Mozart music, it can be found that frequencies around 1500Hz are main frequency components in the Mozart music. This offers us a scientific way in study of music effect on propagation growth.

Fig. 8 .

 8 Fig. 8. The octave analysis chart of Mozart music (Allegro Molto)

Acknowledgments

Research grant support from the Key Laboratory of Eco-Agricultural Environmental Engineering and Intelligent Equipment of China Agricultural Ministry (Grant Number: 588040*172210214 [2]) is acknowledged.


Xi Wang

Hui Gao

Agriculture Wireless Temperature and Humidity Sensor Network based on ZigBee Technology

Keywords: agricultural production, temperature and humidity, wireless network, sensor 1

Combining with agricultural production practice, we propose the agriculture wireless and humidity sensor network design, which is based on ZigBee technology. And we use the chip based on the CC2530 ZigBee protocol as the sensor nodes and coordinator nodes for data collection, transmission and display, aiming to realize the agricultural production automation and precision agriculture.

Introduction

At present, many aspects of production and life need extracting and processing temperature and humidity information of the surrounding environment. In the past, technology was to collect temperature and humidity information by the temperature and humidity sensors, and to transmit the data to the monitoring center by the RS-485 bus or field bus again, so you need to lay a lot of cables to collect and process temperature and humidity information. Traditional agriculture mainly uses isolated, no communication ability of mechanical equipment, and mainly relies on the person to monitor crop growth status. However, if ZigBee wireless sensor network technology is used, the agriculture will gradually shift to information and software-centric mode of production, and use more automation, networking, intelligent, and remote control equipment to farming. Sensors may collect the information such as soil moisture, nitrogen concentration, pH, precipitation, temperature, air humidity, air pressure and so on. The above-mentioned information and the locations of the collected information are passed to the central control equipment for decision-making and reference through the ZigBee network, so we can identify problems early and accurately for helping to maintain and increase crop yield.

In many data-oriented wireless network transmissions, low cost and complexity wireless network are widely used.

ZigBee Technical Features

ZigBee technology is a short distance, low complexity, low power, low data rate, and low-cost, two-way wireless communication technology, employed mainly in the field of automatic control and remote control, can be embedded in a variety of devices to achieve their automation [START_REF] Zhai | ZigBee Technology and Application[END_REF] . For the various existing wireless communication technology, ZigBee technology will be the lowest power consumption and cost technology.

Transfer rate of ZigBee data is low, ranging from 10KB/s to 250KB/s and focusing on low-transmission applications. Under low power standby mode, the two ordinary No.5 batteries can last 6 to 24 months. ZigBee data transfer rate is low, and its protocol is simple, so it greatly reduces the cost. Network capacity is large to accommodate 65,000 devices. Delay time is short, usually in the 15ms ~ 30ms.

ZigBee provides data integrity checking and authentication capabilities, using AES-128 encryption algorithm. Flexible working band, the use of frequency band 2.4GHz, and frequency bands are unlicensed. Such good points as the reliable transmission and the use of collision avoidance strategies are included while the business that requires a fixed bandwidth is reserved specific time slots.

3

Overall system design concept

Based on ZigBee wireless technology, the temperature and humidity sensor network is composed of three parts: the transmitter, receiver and display system. Transmitter is constituted by a number of terminal nodes; each node consists of a temperature and humidity sensor and a ZigBee wireless RF module. Greenhouse temperature and humidity sensors collect information on temperature and humidity, then temperature and humidity data is transmitted to the ZigBee wireless RF modules. Correction of the temperature and humidity data is processed via a chip embedded in ZigBee wireless RF (radio frequency) module,and the data revised will be sent to the receiver through ZigBee wireless network. Receiver consists of a ZigBee RF module and an RS232 serial port module. Receiver module that is a network coordinator establishes a star structure of the network. The data of each node is received through ZigBee network and transmitted to the display system via RS232. This is the temperature and humidity collection and delivery process of a sending node of the system. enabling the node miniaturization [START_REF]CC2530 Data Sheet 1[END_REF] . CC2530 wireless single chip is characterized by very low power, standby current consumption of only 0.2μA. Under the run of 32 kHz crystal clock, the current consumption is less than 1μA.

The temperature and humidity sensor SHT11 integrates several circuits into a single chip, such as temperature and humidity detection, signal amplification conditioning, A/D conversion and digital communications interface. Humidity measuring range is 0 ~ 100% RH, temperature measurement range is -40℃ ~ +123.8℃, humidity measuring accuracy is ± 3.0% RH, temperature measuring accuracy is ± 0.4℃, and the response time is less than 4s. For digital interfaces, SHT11 provides two-wire digital serial interface SCK and DATA; SCK is the serial clock line for communication between the microprocessors to achieve synchronization. DATA serve as the serial data line, and makes the data transmission between the microprocessors. The chip interface is simple, good at high transmission reliability, and measurement precision can be adjusted by programming. After the measurement and communication, low-power mode is automatically transferred.

The hardware design of the transmitting node

Transmitting node is the basic unit of the network composed of digital temperature and humidity sensor SHT11 module, CC2530 processor module, antenna module, power supply module. It is responsible for acquiring temperature and humidity data and data preprocessing, and they will be transmitted to ZigBee receiving end. Temperature and humidity sensor module is responsible for collecting and detecting temperature and humidity data of region. Processor module makes analog-digital conversion for the collected data signal, and then processes. The processed data is issued by the antenna [START_REF] Liu | Research on ZigBee wireless Sensors Network Based on ModBus Protocol[END_REF] . The power module mainly supplies power for the processor. Transmitting hardware framework is shown in Fig. 2.

Fig.2. Transmitting hardware framework

The hardware design of the receiving node

Receiver node is composed of a power supply module, a key module, a serial module, a LCD module, LED lights, a CC2530 processor module and an antenna module. The wireless temperature and humidity sensor network is not an independent communication network, which needs transmitting the monitoring temperature and humidity data to the host computer and displaying them. LED indicator lights are used to display the receiving node network state information (e.g. whether the network is built successfully); LCD module is an interface of the user and sensor network to display the function menu, and the user selects them In IF processing stage, before the signal into the demodulator is amplified and filtered, the data of demodulation is put into the shift register, and then into RFBUF. After the temperature and humidity data in RFBUF are removed by MCU, they will be put into the data buffer register SBUF of UART, and be transmitted to the host computer through RS232 serial module 5 System Software Design

The system using development environment is IAR7.51A while the using protocol stack is Z-STACK of TI. The system connecting the receiving end to PC via the serial port RS232 must know the network address of each sensor node, requiring that the network address is sent to the receiver after each sensor device joins the network. The receiver receiving the network address of the sensor establishes address table to store so that the user collects data of each sensor according to address table when collecting data [4] . Transmitter and receiver software flowchart is shown in Fig. 3. allowing any network device to initialize the service search [START_REF] Song | Wireless sensor network node design and implementation[END_REF] , and can bind other devices that will provide full service, offering commands and control features for the specified set of conforming devices.

Central control center is connected to a number of the sending end through the network connection. Wireless information transmission between the receiver and transmitter is achieved via Zig Bee technology. The sender is responsible for detecting and processing data and sends it to the receiver. The control center gets the collected relevant information through the network. Multiple senders are distributed in the sensor network, so polling scan is put to the upload data from different ID sink nodes and data of sink nodes can be orderly, completely transmitted after being treated through MCU.

Conclusions

This paper proposes a wireless temperature and humidity sensor network system based on ZigBee technology, and networking ways are of flexibility, adaptability.

Through the practical application in the laboratories and its surrounding offices, this system is proved to be very practical. In practical applications, terminal device number is determined by achieving goal demands. The system can be applied to agricultural production, as well as in more areas of production and life, solving monitor environmental temperature and humidity problems in the areas of high cost and inconvenience arrival of wired network cabling, abominable environment. ZigBee networking ways typical of simple and low power consumption make the temperature and humidity information in real-time delivery reduce system costs, save energy, and conserve resources, and its low cost for the promotion in industry provides convenience. With ZigBee chips at lower prices, the new temperature and humidity monitoring system will also have a broad application prospect.

Fig. 1 .

 1 Fig.1. Overall system simulating scheme

  . CC2530 is a data-receiving mode. When data is received, RF receiving signals are amplified by the low noise amplifier before they are overturned into the frequency mixer. By mixing frequency, IF (intermediate frequency) signal is produced.

Fig. 3 .

 3 Fig.3. Transmitter and receiver software flowchart


Jinqiu Zou

Qingbo Zhou
email: zhouqb@mail.caas.net.cn

Peng Yang
email: yangp@mail.caas.net.cn

Wenbin Wu

Development and Application of a Farmland Test Data Processing System Designed for Wireless Sensor Network Applications

Keywords: Wireless sensor networks (WSNs), Measured value, Monitoring

Data collected by measuring farmland environmental indicators are vital sources of agricultural information. Wireless sensor networks (WSNs) have been employed to acquire stable and real time farmland environment data. WSNs, recognized as one of the latest development trends, recently attracted widespread attention and application due to their relative economy, stability, and sophistication. In this study, based upon a large amount of WSNs-obtained data, Microsoft Visual Studio 2005 and ESRI ArcGIS Engine 9.3, amongst others, were utilized to develop a farmland test data processing system, resolve information storage and utilization problems and conduct system applications. The data processing software consisted of four modules: data receiving conversion, database maintenance management, data browsing analysis and the generation and application of data spatialization outputs. Specifically, the data receiving conversion module was mainly responsible for converting raw data acquired by WSNs into standard database outputs, including the automatic reception of measured value, error correction and alerting the observer to abnormal data. The Database maintenance management module's primary functions were the generation and maintenance of metadata generated from stored data, authentic data enquiry, display and analysis. The generation and application of data spatialization products module was principally for the spatial expansion application of measured data, including space-time interpolation and conversion. The system underwent pilot scale testing and improvement at the same time as undertaking the processing of real data collected by WSNs deployed throughout the Hebi test zone. The observed results revealed that the system was able to complete real-time conversion and management of field measured data. In addition, it has several advantages, such as, excellent stability, perfect functionality and a convenient human -machine interface.

Introduction

Crop farmland ecological environment indicators mainly consist of soil temperature and humidity, air temperature and humidity, photosynthetically active radiation and leaf area index, all of which are indispensable data when assessing an area's suitability for agriculture [START_REF] Cao | Investigation and analysis of agricultural condition information demand in China[J][END_REF] . In addition, these parameters are strongly linked to crop growth, which is closely correlated with final crop yield and agricultural production efficiency. How best to acquire accurate farmland environmental and soil data and map any space-time dynamic changes that may occur has caught the attention of agriculture departments and scientists both at home and abroad. Some studies looking at information acquisition tools and precision evaluation have been undertaken [START_REF] Li | The technology development of agricultural condition information Both Abroad and Home[END_REF] . Farmland information acquisition tools in particular have undergone constant innovation and change, evolving from artificial spot observations towards assistant observation by remote sensing technology or short-distance wireless collection based upon a PDA and the mobile phone. To date, this tool has developed into a field information collection system integrating accurate positioning and farmland WSNs incorporating the analysis and visualization of field data [3] .

New generation WSNs [START_REF] Gong | Wireless sensor network as a new ground remote sensing technology for environmental monitoring[END_REF] are an integrated technology using computer science techniques, MEMS sensing techniques, network communication techniques and embedded systems. They represent the main trends in the post-PC era for information science technology and also exist at the leading edge of current information science technology. WSNs serve as an important technology that automatically records a range of different data from the physical world. WSNs have become one of the most appealing and vibrant research fields and are regarded as a great opportunity for information technology and application due to their low deployment and maintenance costs, convenient upgrades, and greatly improved mobility that requires no cable connections [START_REF] Song | Wireless Sensor Networks[END_REF][START_REF] Mao | Survey on wireless sensor network applications[END_REF][START_REF] Yang | Iterative Joint Source Channel Decoding For Multimedia Wireless Sensor Networks[END_REF][START_REF] Liu | Design of wireless image sensor node based on nRF24L01[END_REF] . By installing humidity sensors, temperature sensors, photosensors etc, beneath the observational zone, various farmland data can be directly acquired or inverted and then the data can be automatically transmitted to a laboratory that can process and analyze the observational data automatically collected by the WSNs. This effectively overcomes the drawbacks in traditional farmland environmental monitoring and investigation, and satisfies the application information requirements of modern agriculture [START_REF] Gao | Development of host computer software for crop water status monitoring system based on wireless sensor networks[END_REF][START_REF] Feng | Research and design of crop water status monitoring system based on wireless sensor networks[END_REF][START_REF] Cai | Design and test of nodes for farmland data acquisition based on wireless sensor network[END_REF] .

WSNs technology has made substantial progress and it now plays a vital role in farmland information data gathering. Present research is mainly inclined to a few front end studies, such as, farmland information collection and information transmission. However, little emphasis has been placed upon back end studies including processing and analysis of the data collected. This study is designed to explore possible application methods for the storage, enquiry, browsing and analysis of measured data based upon the WSN platform. Microsoft Visual Studio 2005 and ESRI ArcGIS Engine 9.3 were utilized to develop a farmland observation data system, integrate the data flow process and the data analysis module to ensure effective application of any data collected. Data obtained by the WSNs was sourced from the sensing network deployed at Hebi city in Henan province which covers a 150 km 2 area of the Institute of Natural Resources and Regional Planning, Chinese Academy of Agricultural Sciences. Thirty-five nodes were placed and a frame of data was collected every 10 min which was then transmitted back to the laboratory via GPRS.

Structure and function module of the processing system

This system aimed to resolve the problems involved in storage and application of WSNs acquired data. To achieve this goal, information processing technologies need to be analyzed to resolve the problems that are associated with, for example: WSNsbased data transmission, current background organization and data application modes. The system must be established under the principles of openness, high-efficiency, and safety [START_REF] Li | Development of remote monitoring system based on μC/OS-Ⅱ embedded technology for agricultural environment[END_REF][START_REF] Li | Study on application of embedded system for the agricultural information acquisition based on WEB[END_REF] .The system structure is shown in Fig. 1.

Fig.1. System structure module scheme

Through requirement analysis and data flow abstraction, the system was divided into 4 modules: data receiving conversion, database maintenance management, data browsing analysis and generation and application of data spatialization outputs. Each module was connected via data utilization flow and each served a specific function forming an integrated data processing system which transformed raw data into various outputs. The system function module scheme is shown below in Fig. 2

2.1Data receiving conversion module

This module received the WSNs data, and served as the data entry portal for the whole system. The main functions included: automatically converting WSN-obtained binary file data into tables in a standard database, embracing automatic operational control of the storage module, acquisition synchronization of the WSNs and the automatic capture and highlighting of abnormal conditions. The WSNs performed long-term operations with no interruption and thereafter the module exhibited stable operation. Considering the flaws existing in machine servers and the network environment, unexpected abnormal errors may arise, such as server breakdown and the system halting and the computer restarting. These results suggest that this module should be able to automatically detect these abnormal conditions and ensure a synchronized link between the local system and WSNs by identifying the underlying cause, auto operation, and network registration. In addition, data remains and losses may be caused by these abnormal conditions. Therefore, this module should evaluate data consistency to avert repeated data storage and data loss. The function module is illustrated as follows Fig. 3 .

2.2Functionality of the database management and maintenance module

This module was mainly designed to record and generate metadata for each indicator measured to complete the fusion between this data set and other data sets including addition and registration of time-space related information. Furthermore, this module was also responsible for revising abnormal values to guarantee that all the observational data stored in the database were consistent with conventional thresholds. When undertaking the database design, metadata technology and a double-backup mechanism were taken into account in order to define an open, standard and integrated series of metadata information for data sets. Metadata was produced while performing data storage and provided a basis for subsequent data enquiry and analysis. Double backups were carried out in the database, one backup served for storing data directly originating from the data receiving conversion module and the second backup was set for qualified standard data after undergoing correction processing.

2.3Functionality of the data browsing and analysis module

This module performed enquiry, browsing, statistical counts and graphics drawing to stored collected data including some fundamental functions such as, storage, enquiry, printing, data analysis and statistics. It also embraced multiple statistical schemes according to time, node, and location. Statistical methods included maximum, minimum and mean values together with frequency figures. Graphics drawing included various diagrams according to time, node, and index type, etc and drawing methods included line graphs, bar graphs, and pie charts.

2.4Functionality of the generation and application of the data spatialization products module

It was specifically designed for multiple applications to observational data. Due to the dot characteristics of observational data, these data had relatively high precision and good representation. Nevertheless, data assimilation and coupling should be performed to monitor the process of crop growth on a large scale and include all the growth features of farmland crops. To realize data coupling, space-time information registration needs to be performed. Therefore, this module was established. It conducted data spatialization according to node and sensor type. The spatialization interpolation module that was designed provided, amongst other features, Inverse Distance to a Power, Kriging, and polynomial fitting.

Key technologies involved in system integration

After comprehensive analysis and testing of this system, the system concentrated on farmland observational data flow processing and continuously handled received data by converting original binary files into visual and usable advanced outputs.

Several key technologies should be comprehensively employed including database technology, data correction technology and data assimilation and interpolation technology.

3.1Database technology

This database involved a relatively large data set originating from a wide range of sources and had discord between time and space resolution. To better organize and utilize the data collected, this system utilized Oracle 10g as a database platform and employed metadata technology to establish a database structure, proper handling of a substantial amount of abnormal data and effectively resolving data organization and storage-related problems.

In the current system, each node acquired a frame of observational data every 10 min(including photo and video clips). At the same time, basic geographical information, statistical data, and partial remote sensing data were also collected. Therefore, data abnormalities and the expansion principle should be taken into account when designing a system module. A plausible module should be created to minimize data storage redundancy, enhance data compatibility, realize data sharing, guarantee data security and browse and handle data efficiently.

The database performed data browsing using standard metadata and put in a high-capacity binary file that was written into the metadata field to enhance browsing speed. Additionally, it could undertake data addition, revision, deletion and browsing based upon metadata technology which accelerated data browsing and digging. During the process of metadata field programming and designing, international standard principles were followed and the procedure aimed to comply with current industrial, state, and international standards. This design procedure also considered the specific requirements of the data characteristics and utilization in this database [START_REF] Xiong | Design and implementation of metadatabased technology platform for data sharing[END_REF] .

A total of 12 fields were designed for metadata. Under the prerequisite of satisfying data enquiry and complete data description, a minimum number of data fields were designed to ease the complexity of metadata fill-in and avert data redundancy.

All storage data were upgraded to perform enquiry, statistical and comprehensive analysis. For real-time acquired farmland indicators and data, correction data were also retained as well as original current values. Both original graphics and inversion outputs were saved for graphics data. Regarding graded outputs from obtained data, relevant regulations were enforced about file names and the evolutionary process of pertinent data were described by using data dictionary technology [START_REF] Fu | Two applications of oracle DD basing on VBA and ASP[END_REF] . In addition, dictionary information was used to establish data indices and increase the efficiency of data utilization.

3.2Data correction technology

In this system, data correction had two correction stages. The first step was data conversion, which corrected the WSNs' deprived, raw and binary data by converting a photoelectricity signal into standard data showing temperature, humidity, and photosynthesis. The second step was to delete abnormal values and mark them as special data for the purpose of averting the negative influence that using these abnormal data can have on overall data quality.

Data correction flow: 1). Data value conversion: The front-end data sensor used in this study was purchased from the open market. These sensors were corrected under a constant temperature/humidity environment before delivery and the correction coefficient was kept in a standard register. The correction coefficient automatically corrected the signals emitted from sensors and simultaneously exported the measured value of digital quantity via a data bus. These initial measured values were mere 'relative values', which required linear and temperature offset correction. These relative data were in binary data format when sent back from the wireless sensor (bit stream). Prior to data browsing and storage, these data should be converted into another format [START_REF] Gao | Development of host computer software for crop water status monitoring system based on wireless sensor networks[END_REF] . Microsoft office Excel 2003 format file was commonly employed. The daily data obtained were saved, according to file acquisition date, as one single file with an extension name of .xls. The data correction procedure was located in the data automatic storage system. A preliminary version of the observational data was created following data storage into the database. 2). Abnormal data handling: Certain large errors or significantly abnormal data may occur that can be caused by impaired sensors and weak photoelectric signals. For example, among the data measured in Hebi city test region, some data showed that soil temperature was below minus 20 ℃ or above 30 ℃ , which were obviously wrong. Those sorts of abnormal temperature/humidity values should be deleted even after data conversion. Otherwise, obvious calculation errors may occur in subsequent analysis (statistical analysis and spatial interpolation value analysis), leading to misleading and inaccurate monitoring outcomes. Therefore, the second step was indispensable. The procedure was undertaken in the database management and maintenance module. The corrected data were the revised version of the original observational data, which could be regarded as reliable raw observational values.

3.3Data assimilation and interpolation technology

To make coordinate use of background data from other test zones and real-time farmland field indicators, obtained data were subjected to further processing enabling different data to have comparable space-time nodes. The first step was to spatialize obtained data using data assimilation and interpolation technology. The modules used during interpolation included weighing interpolation, Kriging, and polynomial fitting methods.

This project innovatively improved the interpolation procedure the system used in this project, performing orientation interpolation assisted by remote sensing graphics and basic geographical data about the test zone. The basic principle and steps were described as follows. Firstly, the plantation graph was extracted depending upon the land-use map and remote sensing graphics of the current period. Through observing GPS information at each observation point, interpolation modules were selected for formal interpolation in the region where there was uniform planting. The interpolation technology is detailed in Fig. 4.

Realization and application of the system

After reviewing the system's targets and requirements, a detailed design was undertaken. All the potential data in the system were cleaned and analyzed and a corresponding database module was established. An Oracle 10g software platform, designed for business, was employed to set up the database. Microsoft Visual Studio 2005 language was used for system modeling and arithmetic packaging and a humanmachine interface was designed. Partial function dynamic databases of ESRI ArcGIS Engine 9.3, amongst others, were used in module integration.

Continuous spatial farmland measured index interpolation images

Current situation of crop cultivation Improved method of spatial interpolation Land-use map

Farmland environment data Ground observation data

Remote sensing images interpretation

During the process of system integration, an object-oriented method was adopted. The integration system first separated the database from the software system, ensuring universality among various software packages. At the same time, under an objectoriented human-machine operation environment, an instrument panel-like data input interface was designed, providing convenience to customers and allowing visual data browsing. A visually friendly interface was designed in the human-machine dialog box. To enhance utilization efficiency of the system, complex and simple operations were automated, allowing unmanned automatic operation. The system products that have been designed have attractive interfaces and are easy to operate and maintain, e.g. the data input interface was designed as the dialog box shown in Figure .5.

All the data obtained in the Hebi test zone, Henan province, were properly managed using this system. Approximately 5040 real-time monitoring data points were acquired daily and then stored in the database automatically. Since the system was deployed in July 2010, it has operated stably and reliably. WSN-acquired data and farmland information from other test zones were utilized to produce multiple forms of data output, that help monitor agricultural conditions. The system particularly played a vital role during the monitoring process of drought damage caused to winter wheat in December, 2010.

5.Conclusion

This study focuses on the processing procedure of WSNs-acquired farmland data. It systematically analyses the information flow during the reception, storage, and analysis processes from farmland data collection. Additionally, this study designed a relevant database module that organized and managed a large amount of collected data. Pertinent software exploration platforms were employed to develop a desirable system for farmland observational data processes.

Application results reveal that software data flow and the integrated module design concept are good. The system has excellent stability and an attractive and simple human-machine interface. It also preliminarily achieves the task of monitoring data flow throughout the whole procedure from acquisition to utilization of the farmland information. Metadata and data dictionary dual techniques were employed in data organization, which improves data browsing and analysis efficiency. At the same time, a commonly used spatial interpolation module had improvements made to its monitoring data spatialization so that there was an increase in the precision of spatial interpolation values. To conclude, the system designed in this study preliminarily achieved the management and utilization functions of WSN-acquired farmland information, supplying an information service for agricultural field monitoring.

FarmlandFig. 3 .

 3 Fig.3. Data reception conversion module scheme

Fig. 4 .

 4 Fig.4. Farmland observational data interpolation flow

Fig. 5 .

 5 Fig.5. Database storage module

Acknowledgments

Funding project: National development and planning project for high-tech research of China entitled Remote sensing farmland information based on satellite and land in coordination with inversion technology (grant No. 2009AA12Z143). Surface project of National Natural Science Foundation of China entitled Simulation research on crop yield per unit based on space-time coupling and data assimilation (grant No. 40971218). And foundation of central institutes(iarrp-2011-15).


Guobing Pan

Xiao Feng

Research on control system of variable rate fertilizer applicator in precision farming based on combined positioning of GPS, electronic compass and gyroscope

Keywords:

On the Background of precision farming and the precision positioning of variable rate fertilization, the precision farming was achieved and the per unit yield was raised by the integrated positioning method using GPS, electronic compass, and gyroscope.

Introduction

China is a great agricultural country, but in a situation of large population with relatively little land. Arable land resources limited, however, China feeds 22% of the world's population with less than 10% of the land in the world. With the rapid development of science and technology, the introduction and experiment of the concept of precision farming, and the new challenges of the traditional fertilization systems, exploration has been made domestically and abroad [START_REF] Blackmore | Precision farming:An introduction[END_REF][START_REF] Blackmore | An system for precision farming[END_REF] . Precision fertilization is only part of precision farming, but with a undefined concept and immature theory and technical system.This paper mainly discussed about the theory and technical system of combined positioning method based on GPS, electronic compass and gyroscope.

2.

Outline of Precision farming and the main technological ideas

Meaning of Precision farming

Precision farming is a modern and meticulous agriculture technology, which based on modern information high-tech and equipment engineering technology.It basically means to adjust the crop input according to soil properties of the crop. In another words, on one hand it finds out the soil properties insides the plot soils and the space mutation of the productivity. On the other hand, it makes certain of the production target and conducts system diagnostic, optimizing formula, technical assembly, and scientific management firmly, so that it can mobilize the soil The fund of structure engineering of chongqing jiaotong university(CQSLBF-Y011-4) The fund of experiment teaching and reform of chongqing jiaotong university(SY1201003) productivity to get equel or higher output with the least or the most economical input, and improve the environment to make the economic benefits and environmental benefits with all kinds of agricultural resources efficiently [START_REF] Lal | Soil management in the developing contries[END_REF][START_REF] Jianjun | A preliminary study on rice nitrogen application decision-making by soil information system -A case study of Dafeng City,Jiangsu Province[J[END_REF] .

Main technological ideas of precision farming

Precision farming includes aspects such as precision seeding, precision fertilization, precision irrigation and precision harvest. However, the development of precision agriculture makes a new requirement for theory and technical of rational fertilization. From the use of fertilizer, the contribution rate on food production is 40%; but the utilization rate of nitrogen is only 50%, phosphorus 30% and potassium 60% even in countries which owns a high fertilizer utilization rate. Low utilization rate of fertilizer makes a higher producing cost, and leads to environmental issues, such as the pollution of underground and surface water, and excessive content of nitrate in fruits and vegetables. In a word, fertilization is closely relevent to agricultural production, product quality, and food and environmental pollution. And the theory and technology of precision fertilization is the key solution [START_REF] Zhijun | Development and performance assessment of map-based variable rate granule application system[END_REF] .

Necessity of precise fertilization

The relationship of soil, crop and nutrient is very complicated. Although the necessary major elements and micro-elements during the growth of crop have been fixed, the degree of nutrient which crops need varies from different plants. The difference in nutrient demands can be great in different growing seasons even for the same crop. Seedling stage is a temporary nutrition period for crop. In this period, there is less requirement for the quantity of nutrient, but the demand of nutrient must be complete, effective and adequate. Many crops need a certain kind of most and best nutrient in the most efficient period of nutrient. The most efficient period of different nutrients for the same crop can be different, and it is also the same with different crops. Different nutrients are irreplaceable, namely, the crop production is limited by the least nutrient which can not be replaced by other nutrients. What is more, the overuse of fertilizer to eliminate restrictions of minimum nutrient rate brings a series of environment problems. Therefor, in order to adapt to different regions, different crops, different soil and different environment for various crops, and to achieve good economic benefit and environmental benefits, variable rate fertilizing is absolutely the key development direction of fertilization in the future [6,7].

Integrated positioning method based on GPS, electronic compass and gyroscope

Combined positioning

It is required for precision fertilization that the agricultural machinery should work on the prearranged route in the field, reach its destination accurately and than complete the work. Precision guiding is one of the key technologies to automate the agricultural machinery, and the positioning accuracy of it directly affects the path tracking of the agricultural machinery. Thus the adoption of efficient and reliable navigation and positioning accuracy should be put to the priority to ensure the path following of agricultural machinery and realize the precision of automatic fertilization. The positioning of agricultural machinery includes heading information and location information. In the respect of navigation technology which mainly based on GPS, RTK-GPS and FOG are taken for existing researches to realize the positioning of the agricultural machinery, but it is of high cost. This paper used GPS of low cost and precision, combined with electronic compass and high accuracy inertial navigation system, to achieve the Precise positioning of agricultural machinery by Kalman filtering, as shown in Fig. 1.

Fig.1 The figure of combined positioning

4.2

Idea of realizing combined positioning 1) Firstly, use pseudo-range difference GPS method to locate the primary location of agricultural machinery.

GPS Pseudo-range Electronic Compass Gyroscope

Precision location after combined positioning

USB Port

Computer、PDA GPS receiver calculates the WGS-84 coordinates by pseudo-range difference. However, the fertilizer application machine uses Gauss plane coordinates, so Gauss projection should be made to convert the coordinates of pseudo-range positioning to Gauss plane coordinates.

2) Use electronic compass and micromachined gyroscope to measure the heading angle of fertilizer application machine, and to predict the best heading angle.

○ 1 The heading angle of electronic compass and gyroscope can be set as

)

dd tt d t k R r R r x u x u kk       (1) 11 ( ) ( 1) ( )(
)

tt dd t d N R r R r x u x u NN       (2) 11 ( ) ( ) ( 1) ( )(
)

td dt td d t k R r R k R r x u x u kk        (3)
When r>N

( )

( 1) ( )( )

dd tt d t N R r R r x u x u NN       (4) 11 ( ) ( 1) ( )(
)

tt dd t d N R r R r x u x u NN       (5) 11 ( ) ( ) ( 1) ( )(
)

td dt td d t N R r R k R r x u x u NN        (6)
In the equation above,  is average sample data,and "N" is displacement distance of window.

○

○ 3 Heading angle "X" can be calculated by equation below.

x x x x X                (9)
3) Use adaptive Kalman filter to recombine and amend the multi-source information including the primary location and the heading angle, locate agricultural machinery and precisely evaluate the heading angle information.

Conclusion

This research realized the precision positioning of agricultural machinery, ensured the principal issue of path tracking quality, and finally achieved the accuracy of automatic fertilization. The precise position after integrated positioning was sent to computer or PDA through USB port. Combined with the data of fertilizing and the field position information from the database, the goal of variable rate fertilization was finally reached, precision farming was realized, and the per unit yield was raised.


Lin Hu
email: hulin@mail.caas.net.cn

Yun Qiu

Guomin Zhou

Research on Orchard Field Data Service System

Keywords: orchard, field data service, diversified terminals, service for orchard workers, precise management

The precise management of orchards cannot do without the support of various orchard field data, and the orchard field data server is an effective solution thereto. The orchard field data server consists of data acquisition unit, data communication unit, data analysis unit and such diversified server sockets of user terminal as supportive personal computer (PC), notebook computer, mobile phone and telephone. The orchard workers can set data acquisition cycle according to the requirements, and the processed data can serve the orchard workers in many respects. After its promotion and application in many orchards in such regions as Liaoning and Beijing, the said system has been proved to be of easy use and reliable effect, so that the project has achieved good social, ecological and economic benefits.

Introduction

China's fruit output ranks No. 1 in the world [1], but its output value is low. The main reason is the low level of production and business operation, which has caused the poor quality of fruits [START_REF] Cheng Cungang | Technological demands and development countermeasures in China's apple industry[END_REF][START_REF] Xiaojun | International competitiveness evaluation and promotion countermeasures in respect of China's apple industry[END_REF]. Consequently, it is difficult for us to compete with such countries as the United States, Italy and Japan in the international market. To improve the level of our fruits, we must enhance the level of business operation. It is the international practice to improve and transform the traditional fruit industry by means of standardization and informatization [START_REF] Guodong | Exploration and practice of the development and export of the apple industry[END_REF] in the industrial production. The basis of the standardization and informatization is the precise control of the basic data in production and management. Orchard is the basic area division in fruit industrial production and the basic organization of production and business operation. Therefore, to acquire, sort out, process and analyze the data in the orchard as a unit, and to use them in serving the orchard before production, during production and after production would constitute the aim of this research. The purpose of the orchard field data server is to acquire the orchard field meteorology and field video. After the data are sent back to the network server, the authorized orchard workers and/or other users are able to refer, in real time, to the orchard field data. After these field data are processed by means of the professional software, they can be used to provide service and guidance for the orchard workers in respect of the production and business operation.

System Design

Aim of the System

Orchard is the basic unit in the production and business operation of fruit industry. So it is in the orchard as a unit that the orchard field data acquisition system designed to provide service for the production and business operation would serve the orchard workers before production, during production and after production. The purpose of this product is designed to improve the orchard workers' level of production and business operation and to strengthen the competitiveness of the products.

Framework of the System

The system consists of field data acquisition unit, data transmission unit, data processing unit and service unit. The field data acquisition unit is used to acquire the orchard meteorology and video data, and the data transmission unit is designed to transmit them into the server through the communication network. After the data are processed and analyzed on the server, they are used to provide service for the orchard workers and/or other clients.

Figure 1. System Frame Diagram of Orchard Field Data Acquisition Server

The field data server consists of such four parts as meteorological data acquisition unit, video image data acquisition unit, data transmission platform and power supply unit. Each of these acquisition units is assembled by such modules as are in conformity with the industrial standards. The meteorological data acquisition unit can be connected with 20 digital meteorological sensors, which would mainly include such sensors as for air temperature and humidity, soil temperature and humidity, photo-synthetically active radiation and carbon dioxide concentration, but could be increased or decreased according to the actual needs. The video image acquisition unit is composed by a group of video cameras, including cable video cameras and wireless video cameras. The data transmission platform is of such functions as video compression and format conversion, voice transmission and data transmission. Two R232 interfaces, two R485 interfaces, one voice input-output interface and one video input interface are used to respectively accomplish the transmission of data, voice and video. Their connections are shown in Figure 2. The device adopts solar power supply, including solar-cell panel, storage battery and programmable digital switch. The programmable power supply timer is connected with the data transmission platform to receive control instructions. The data transmission platform is the core of the orchard field data server, including four video channels, one audio channel, two R232 channels and two R485 channels, and also including the built-in audio and video compression and format conversion functions, GPRS and WCDMA communication modules, and GPS positioning module.

Meteorological Sensor

Imaging Sensor

Data Transmission Platform

Application Cases

It is with the support of the MOST's State High-tech Program (863) and the Program of Commercialization of Agricultural Research Findings that this system has been gradually developed and matured. In recent years, this system has been applied to many aspects, which has achieved very good social and economic benefits. In the following, the "Hot Line of Orchard Workers" is taken as the case of application to analyze and demonstrate the application and functions of the orchard field data service system.

The "Hot Line of Orchard Workers(http://www.cart.net.cn/)" is an agricultural information service platform in the comprehensive network jointly developed by the Institute of Agricultural Information and the Institute of Pomology of the Chinese Academy of Agricultural Sciences. By use of the "four-in-one" approach of website, telephone, mobile phone and TV, the "Hot Line of Orchard Workers" is designed to provide all-sided and public beneficial agricultural information service for the orchard workers throughout the country, which is related to the latest information on fruit trees and nursery stock, market price quotations, practical cultivation technique, fruiter disease control technique, and so forth. It is the good helper and friend for the orchard workers to acquire wealth.

The system has been developed on the basis of the orchard field data service system. And the system application has been extended and developed on the basis of the functions of the orchard field data service system. The system interface of the "Hot Line of Orchard Workers" is shown in Figure 4.

The system functions include home page, nursery stock recommendations, online consultation, technical service, production and marketing service, market information, expert system and training classroom on-line.

The system data are supported by 20 orchard field data servers, which are located in 20 orchards in China's Liaoning Province and Beijing. The orchard field meteorological data are acquired once every 20 minutes, and the image data are collected once every four hours. If necessary, it is possible to make recording of the video or real-time monitoring of the orchard field. Figure 5 is the schematic diagram of the orchard field data server, which is located in a certain orchard located in Shunyi District of Beijing.

Discussion

The orchard field data server is a set of intelligent maintenance-free system, which is all integrated by such modules as are of independent functions. It is so safe and easy to use with stable performance that it has achieved satisfactory results after trial use in some provinces and cities in northern China. It is particularly suitable for the orchard data acquisition service in such districts that are unattended and/or inconvenient in power supply. At present, the existing problems are focused on the following aspects:

The first is the determination of the battery capacity. In northern China where most of the days are sunny, this system can satisfy the use in most regions, since it can supply power for 20 consecutive hours, in which it can satisfy the power utilization of the system for one week if the system works two hours per day. On such special occasions as necessary to make consecutive video monitoring, consideration may be made to use the electric supply. But in southern China, in some extreme weathers in the rainy season, it may be difficult to satisfy the power supply. In such cases, it is recommended to change even higher capacity of storage batteries and even larger size of solar panels.

The second is the acquisition of video images. In the system's automatic video recording, it may be influenced by the light intensity. In such cases, consideration should be made to add a light intensity detecting unit to the system to automatically adjust the lens angle, so as to ensure the quality of the video and images.

Figure 2 .

 2 Figure 2. Connection Diagram of Field Data Server In Figure 2, the solid line indicates the circuit diagram, but the dotted line indicates the signal transmission diagram.The data transmission platform is the core of the orchard field data server, including four video channels, one audio channel, two R232 channels and two R485 channels, and also including the built-in audio and video compression and format conversion functions, GPRS and WCDMA communication modules, and GPS positioning module.

Figure 3 .

 3 Figure 3. Schematic Diagram of Systemic Functions

Figure 4 .Figure 5 .

 45 Figure 4. Interface of "Hot Line of Orchard Workers"

Acknowledgments

It is with the support of the Project of "Remote Intelligent Diagnosis System of Field Crop Diseases and Insect Pests (2007AA10Z237)" of the State High-tech Program (863) and the Project of "Remote Intelligent Diagnosis System of Orchard Diseases and Insect Pests and Pilot Plant Test (2009GB23260457)" of the Commercialization of Agricultural Research Findings that the orchard field data service system has been accomplished, for which we would like to extend our heartfelt thanks.

The meteorological data acquisition unit and video image acquisition unit are used to transmit the signal to the data transmission unit. After various built-in processing, the signal is sent to the public network through the GPRS or WCDMA module. In the built-in communication module, there is a communication signal strength monitoring module, which would automatically use the GPRS module for transmission if the 3G signal becomes very weak. After the data are transmitted back to the server, they are to be stored in the database. It is not necessary to give more details in respect to the design of the database.

Framework of the System Functions

The application of the system can be designed and developed according to the requirements of the clients. Its core functions are designed to cover the meteorological data service and video image service, but a lot of extended applications can be developed according to the requirements of the clients. The frame diagram of the systemic functions is shown in Figure 3.

Data Layer


Yanmin Wang

Yuchun Pan

Bingbo Gao

Zhenyu Zhang

Bingjun Li

A Monitoring and Management System for Farmland Environmental base on Flex and Web Services

Keywords: Geospatial Information System, Farmland Environmental Management and Monitoring, Geospatial Web Services, Flex

Farmland environmental deterioration is the main reason which results in the agricultural product quality problems, so it is necessary to build a geospatial information system for farmland environmental monitoring and management. The rapid development of portable farmland environmental surveying or sampling devices and sensor network have made this possible. In this paper, we describe the design and implement of the geospatial system based on Flex and Web Services. This system provides data management, geoprocessing, visualization, as well as analysis functions to mine potential valuable information to support decision making based on the sampling data and other collected environmental data of farmland. Geoprocessing is implemented by directly invoking Geo-processing Web Services or calling Server APIs. To enhance the usability, the system also provides a flex client for users and web service interfaces for client program. Tertiary user structure with strict privileges management is designed to protect the users' data copyright.

Introduction

The security of agricultural food has been one of the most concerned issues in most countries in the world. The agricultural product quality problem has mainly come from farmland environmental deterioration. The overuse of fertilizers, abuse of pesticides and the heavy metal pollution are the main causes of the environmental deterioration of farmlands. In China, 1.6 million hectares of farmland has been polluted by pesticides, 4.8 million tons of fertilizers are being applied to the farmland every year [START_REF] Shi | Effects of Pesticide Contamination on Microbial Diversity (in Chinese)[END_REF], and more than 20 million hectares of farmland (that's more the one fifth of the total) have been contaminated by heavy metal [START_REF] Chen | Behavior of Cu and Zn under combined pollution of 2,4-dichlorophenol in the planted soil[END_REF][START_REF] Li | Soil Environmental Pollution and Agricultural Product Quality (in Chinese)[END_REF][START_REF] Wang | Present situation and problems in studies on environmental qualities of agricultural products producing sites in China (in Chinese)[END_REF]. The Chinese government is paying more and more attentions on Supported by: Beijing Municipal Natural Science Foundation (4102022)& key Projects for Constructing Scientific and Technological Innovation Ability of Beijing Academy of Agriculture and Forestry Sciences.

First author: Yanmin Wang, E-mail:wy_min@sina.cn *Corresponding author: Yuchun Pan, E-mail: panyc@nercita.org.cn the farm land environmental quality and has initiated a series of projects to control the contamination and repair the contaminated soil. To achieve these goals, the primary thing needed to perform is to fig out the pollution status of farmland. The development of sensor network makes it possible to monitor and the emergence of portable sampling equipments with acceptable prices such as TXRF7 and X-MET5000 makes it possible to build farmland environmental information base [START_REF] Huang | Portable Unit for Rapid Determination of Pesticides Residues in Vegetables and Fruits (in Chinese)[END_REF][START_REF] Yenisoy-Karakas | Validation and uncertainty assessment of rapid extraction and clean-up methods for the determination of 16 organochlorine pesticide residues in vegetables[END_REF]. However, the management and utilizing ability of the collected farmland environment data is very limited in China.

As an effective technology to manage, display, process and analyze the spatial related data, GIS (Geographical Information System) has been applied into many fields. By using WebGIS technology the spatial information and GIS application can be shared over the Internet easily. The ESRI ArcGIS

Server provides a flexible framework to create and configure GIS services and applications [START_REF] Liang | A GIS-based expert system for pastoral agricultural development in Gansu province, PR China[END_REF][START_REF] Mccarthy | An integrated gis-expert system framework for live hazard monitoring and detection[END_REF] 2 System Design

System Structure

The MMSFEFW is composed of data layer, service layer and view layer, shown in fig 1 .The data layer contains base data, sampling data, information of system users which can be spatial or non-spatial data.

The spatial data is managed by relational DBMS (database management system) and the spatial data engine (in this paper the ArcSDE of ESRI is adopted). The non-spatial data are stored in the relational database and managed by relational RDBMS (Relational Database Management System).

The service layer is composed of spatial service layer, application logic layer and the interaction layer. The ArcGIS Server is paced in the spatial service layer to provide spatial information and functions through spatial services and Server API. The application logic layer acts as the Model of (2) Query and analysis group: this group includes functions to query data using attributes restrictions and spatial location or relationship restrictions, apply spatial analysis on the sampling data, evaluate the quality farmland plots, display the results of analysis and evaluations on thematic maps and support users to set levels and rendering colors the results.

(

Data Organization

The data of MMSFEFW include basic data, sampling data of farmland environment and user information. Basic data are composed of different kinds of data, including remote sensing images, terrain data, administrative map, and land use data and so on. The sampling data include observation data of soil, atmosphere environment and water environment of farmland and the metadata describing the observation data. User information includes basic user information and the role and privileges assigned to the user.

Google map is employed to provide background map so images and terrain maps were not built into the database. Other basic data like administrative map, land use map, were publish into ArcGIS Server to provide web map service after being organized into different map documents and given proper styles and visible ranges. Because those background data are stable and do not change frequently, map tiles are created beforehand at 20 scale levels same as Google map. After that, when the server received a web map request, it only needs to return the tiles within the extent at proper scale level. Thus the responsive time is shorted sharply for there is no need to render the map in-time.

The sampling data were represented by point feature type with a point geometry attribute and other non-spatial sampling attributes. The farmland plots data were represented by polygon feature types with a point geometry attribute and other non-spatial attributes. Because the number of non-spatial attributes of sampling data and farmland plots can be accustomed and thus is not fixed, the spatial attributes and the non-spatial attributes are stored in different tables. For example the sampling data, the points was stored in a spatial data table and other attributes are stored in normal table and they are connected with the object id. The metadata of the non-spatial attributes are stored in the meta-table table

Fig. 3. Architecture of calling ArcObjects of ArcGIS Server in Web Application

Flex and BlazeDS

Adobe Flex is a software development kit (SDK) released for developers to develop and deploy cross-platform RIA (Rich Internet Applications). Developers can use the MXML (an XML-based markup language) to lay out graphic user interfaces and use ActionScript to achieve interactivity. The codes would finally be compiled to Flash files which has got wide support and has affluent expressive force. By using the computing ability of client computer to solve multi-step processing, client-side validation, data management and the communication times between clients and server can be reduced and web application will become responsive [START_REF] Jiang | Design and Realization of Enterprise Web Application System Based on Flex3[END_REF][START_REF] Longley | Advanced Spatial Analysis[END_REF][START_REF] Webster | Developing Rich Clients with Macromedia Flex[END_REF].

BlazeDS is an open licensed java remoting and web messaging products of Adobe to simply developers' work to access back-end distributed data or push data to the RIA client. A BlazeDS application consists of two parts: a client-side application and a server-side J2EE web application. The client-side can be realized by Flex or Ajax libraries. Flex provide components such as HTTP Service, Web Services, Remote Object, Producer and Consumer to communicate with the BlazeDS server. The BlazeDS server running in J2EE Server container can provide proxy service, RPC service, messaging service and service adapter. Channels which encapsulate message formats, network protocols, and network behaviors are used by client to communicate with endpoints on sever. BlazeDS provides several types of channels, including standard and secure Action Message Format (AMF) channels and HTTP (AMFX) channels. AMF and HTTP channels support non-polling request-response patterns and client polling patterns to simulate real-time messaging [START_REF] Cardell-Oliver | Field Testing a Wireless Sensor Network for Reactive Environmental Monitoring[END_REF][START_REF] Fukatsu | Field Monitoring Using Sensor-Nodes with a Web Server[END_REF].

System Realization

Realization scheme

The MMSFEFW is of B/S (Browser/Server) structure and realized with J2EE technology. The client interface was built using Flex Builder and BlazeDS is employed to finish the communication between clients and server. The web module in the application logic layer was realized using Struts2 and the Axis2 was used to implement Web Service in this layer. ArcGIS Server 9.3 is adopted to act as the GIS Server to provide spatial services and spatial functions. ArcSDE and Oracle is used to manage the data.

Realization of Geoprocessing

ArGIS Server allow users to publish model or script tools created in ArcTool Box, or map document container tool layers to server to provide different kinds of geoprocessing service(GP Service). In addition more flexible geoprocessing can be realized by invoking the server APIs in program. In MMSFEFW both methods were used to process and analyze the sampling data.

Geoprocessing using GP Service of ArcGIS. A GP service in ArcGIS Server is created in two steps.

First, build geoprocessing tools on ArcGIS Desktop using model or script tools or creating a map with the built tools as tool layer. In these step much attention need to be paid to following three points: [START_REF] Shi | Effects of Pesticide Contamination on Microbial Diversity (in Chinese)[END_REF] the data types of input parameters and output parameters because unlike the desktop environment only some certain data types are supported on web application clients. ( 2) the place where middle data and the result data will be stored. ( 3) how the result will be displayed to the clients. The second step is to publish created tools or map with tool layer. The parameter defining the way in which the service will run and interact with the clients can be set in this step. The analysis of distribution of farmland pollution is realized in this method.

Fig 4 shows the model to using IDW as the spatial interpolation method to analyzing the spatial distribution of harmful substance. The flow of this model have three steps: firstly filter the samples data so that only the data to which the current user at least has read privilege will be used; secondly apply IDW method to the selected sample points within a certain spatial extent; Thirdly classify the results of IDW method according to the thematic classes set by users and set the color scheme of the output.

The Inputs of the model include userids, Extent, Z_value, Cell_size, Reclass_Idw and symbol.

Userids are numeric identifies of users whose sampling and plots data can be read by the current user,

Client

Web Server ArcGIS Server

Evaluation Results

Geometries

Sample Points

Fig. 5. The interaction among client, web application and ArcGIS Server during the operation evaluating the quality farmland plots

User Structure and the privileges managements

The tertiary user structure was designed realized MMSFEFW, shown in Fig 6 . Users are grouped into different user groups, and each group has group administrators who are responsible for management of the users and data belonging to their group. The users and the user groups forms the lower two layers of the structure. At the top of the structure are the system administrators who have the highest controlling authority, responsible for configuration of the system and management of the user groups.

In order to protect the rights of system users, strict privileges management scheme are adopted. Each user is assigned one or more roles which define the operations that can be performed and the data can read or written. A user with the reader role can only view, query or perform some spatial analysis on the environmental sampling data or farmland plots data belonging to users in the same group.

Results

The interface of MMSFEFW uses the national map of China as background, and provide map control panel, menu bar, toolbox and information window. The menu contents differs after logging in according to the user's roles and privileges and the map will scale automatically to the extents of sampling data to which he has at least read privilege. The MMSFEFW built using Flex, Web Services, ArcGIS Server and J2EE includes data layer, services layer and presentation layer. The flex was employed to realize the user interface. The spatial visualization and analysis were realized by directly calling configured rest services in flex clients or invoking ArcObjects of ArcGIS Server. To protect user's copyrights on sampling data, tertiary user structure was design and strict privileges management was implemented.

Further works include: 1) additional kinds of environmental data; 2) new environmental analysis models to provide better results for decision-making.

Fig. 2 .

 2 Fig. 2. Functional block diagram of system

  Extent represent the spatial extent to apply the spatial interpolation, the z_value represents the attribute sample points to be analyzed. The Cell_size assign the actual size each pixel represents. The Reclass_Idw and symbol respectively contains the classes division and symbology set with functions described in 2.2 section. The two outputs of this geoprocessing tool are named Idw_sp_650001 and Recess_Idw which are all of Raster type. Idw_sp_650001 is the result of IDW spatial interpolation method. Reclassfication is the result of reclassifying of Idw_sp_650001 according the input parameter Reclass_Idw.

Fig. 4 .

 4 Fig. 4. Geoprocessing Tool The accomplished model can then be published to the ArcGIS Server to provide geoprocessing service. The geoprocessing services can be directly called in flex. Following is the codes snippets calling the spatial interpolation service in asynchronous mode. The interpolation function calls the spatial interpolation service and the jobCompleteHandler function retrieve the result after the task completed. The following is the code snippet of clients to call the service. var params:Object = { "Extent":interpolateExtent.xmin+" "+interpolateExtent.ymin+" "

Fig 7 ,

 7 Fig 8 and Fig 9 are the screenshots of MMSFEFW. Fig 7 shows the thematic map of Cu contents in each sampling points. Fig 8 shows the environmental quality evaluation results of the selected farmland plots. Fig 9 shows the spatial interpolation results of Cu contents in the specified area.

Fig. 7 .Fig. 8 .

 78 Fig. 7. Thematic map of copper contents in each sampling points

Fig. 9 .

 9 Fig. 9. Spatial interpolation results of Cu contents in the specified area

  , while Adobe Flex which has distinct advantage over traditional web technologies in giving an expressive interface and more effective communication mechanism becomes the most popular RIA (Rich Internet Application) technology. Therefore, in this paper, Web Services, ArcGIS Server, Flex as well as J2EE technology are employed to build the MMSFEFW(abbreviation of A Management and Monitoring

System for Farmland Environmental base on Flex and Web Services) to effectively manage, display and analyze the collected farmland environmental data. The design, key technologies and implementation of MMSFEFW are discussed in section 2, section 3 and section 4, respectively.

Fig. 1. System structure 2.2 System functions

	Aimed at managing, visualizing and analyzing the detection data of environment sampling data of
	farmland, mining the potential value of the collected data, serving data collector, data manager, experts
	and researchers, related government officials and the public, the MMSFEFW is designed to contain
	three function groups, namely data management group, query and analysis group, and system
	management group, shown in fig 2.
	clients and the application logic layer, contains web module for web browsers and web service for (1) Data management group: This group contains functions that support the upload, query and
	client program. The former plays as the controller of MVC architecture and the latter provides standard editing of the farmland plot data and the sampling data collected by fixed monitoring sites or
	interface for client program to access system functions. survey activity. For the plots data many common GIS data formats are supported, such as Shape
	The view layer is designed to possess two kinds of interface, they are flex interface for users and file of ESRI, GML and so on. The sampling data can be uploaded in Microsoft Excel file, plain
	Web Services interface such as WSDL (Web Service Description Language) for client program. The text file or XML file.
	flex client, written using action script and Adobe tags would finally be compiled to a swf (shock wave
	flash, a binary file of Adobe Company) files and downloaded to users' web browsers to provide a vivid
	interface which communicates with the server to get data, write data and call functions according to
	users' operations. The Web Services interface provides service invoking information such as address,
	operations, input and output parameters and accepts users' request in SOAP (Simple Object Access
	Protocol) Envelope.

MVC (Model-View-Controller) architecture. It contains the basic function module which encapsulates the common supporting functions into Classes of appropriate granularity and the logic module carrying out the system functions by calling the basic function module. The interaction layer, working between

  and the M_Sample_Fields table. Every sampling point and farmland plots has an attributes named attribute showing which user it belongs to. Besides the spatial index built on the geometry attributes, index must be created on the "owner" attribute because the data access control which is very frequent in MMSFEFW is base on it.Three tier user structure (induced in 4.3) is adopted in MMSFEFW, so user information, user group information, roles and privileges need to be stored. User table, group table, roles table and privileges table were created to store this information.ArcGIS Server provides the framework to create and configure GIS services and applications. It is a GIS web server software supporting users to configure and publish spatial resources (data, map, functions) as REST style Web Services or SOAP style Web Services, for example mapping service, image service, spatial data service, geocoding service and spatial processing service. Two steps are required to publish a spatial resource as web service: first create a spatial resource use the ArcGIS Desktop, then publish the resource into ArcGIS Server through ArcCatalog or the ArcGIS Server Manager.

	Data Management "owner" 3 Key technologies	A Geospatial Information System for Farmland Environmental Management and Monitoring System Management Query and Analysis
	3.1	Monitoring Site Configuration ArcGIS Server Sampling Data upload Plots Data Upload	Sampling Data Management	Plots Data Management	User Management	System Configuration	Sampling Data Query	Plots Data Query	Levels and Colors Setting	Analysis Environment Quality
		Flex					GIS Server
		Client		Web Application Server
				Web Application						SOC
									AO		AO
		Flex Client		Java Objects	ArcObjects Proxy	Server Object Manager		AO	SOC	AO
										SOC
		Flex Client							AO		AO

ArcGIS Server provides developers with Server APIs which are actually coarse-grained ArcObjects to connect and get objects from the server. Developers can invoke fine-grained ArcObjects through the Server APIs to fully employ the powerful spatial data process and analysis ability of ArcGIS. The architecture of calling ArcObjects of ArcGIS Server in Web Application is shown in Fig 3

.

The web application server acts as a bridge that connects web clients to the spatial operation and analyzing functions of ArcGIS Server. The web application server and GIS server can reside in different computers. The web application written in java or .net uses ArcObjects proxies which then communicate with the SOM (Server Object Manager) using XML format messages and HTTP protocol to revoke the ArcObjects in the SOC (Server Object Containers). What need to note is that it's the ArcObjects residing in the SOC that actually implement the spatial operation or analysis functions.

ArcGIS Server also offers developers ADF (Application Developer Framework), a robust, standards-based set of components for building and deploying geospatial applications and services. For Java platform, there are the Web ADF for building and deploying Web applications and services base on JSF (Java Server Faces) and Enterprise ADF components for deploying business-tier EJB (Enterprise JavaBeans) applications

[START_REF]The Best of REST Using REST in ArcGIS Server 9[END_REF][START_REF]Overveiw of ArcGIS for Server[END_REF][START_REF]ArcGIS API for Flex online Help[END_REF][START_REF]The ArcGIs Server and image server architecture[END_REF]

.

  Hecannot input, update or remove the data. A user with the writer role can input environmental sampling data or farmland plots data, update, remove and group the data belonging to him besides what a user only with a reader role can perform. A user with the group administrator role can update, remove and group all the data belonging to the users of the group besides what user with a writer role can do. Users with the system administrator role have the highest controlling authority, that's to say they can use all functions the system provided and manage all the data the system have.Every user in the system has the privilege to alter his own information except which group he belongs to. A group administrator can add, delete, and alter users in his group. The system administrator can add, delete and alter user groups and group administrators.

	1popedom		System Admin
	purview
	2popedom purview	GroupAdmin1	GroupAdmin2	GroupAdmin3
	3popedom purview	User1 User2 Usern	User1	Usern	User1 User2 Usern
		Fig.6. Tertiary User Structure

Acknowledgments. This research was supported by Beijing Municipal Natural Science Foundation (4102022) and key Projects for Constructing Scientific and Technological Innovation Ability of Beijing Academy of Agriculture and Forestry Sciences. The authors would also like to thank any reviewers for their constructive comments and suggestions.