Michele Imbruno
email: michele.imbruno@uca.fr

Grégoire Rota

Catherine Araujo Bonjean

Keywords: Trade policy uncertainty, Import behaviour, World Trade Organization, Tariff binding, China. JEL Codes D22, F13, F14

This paper empirically explores imports' adjustment to reductions in trade policy uncertainty (TPU) considering that firms may face large sunk costs to purchase foreign goods. We investigate how product-level Chinese imports react to tariff binding connected to China's accession to WTO, through distinguishing both country-related margins and firm-related margins. Our main results suggest that a decline in TPU allows the access to a greater variety of foreign goods, associated also with a higher quality. At the same time, tariff binding leads more Chinese producers and trade intermediaries to start importing, allowing more firms and consumers to enjoy potential gains from imports. Finally, we document heterogeneous TPU effects across firms with different ownership, and products with different end use, revealing interesting insights in a context of global value chains.

Introduction

It has been well established in international trade literature that firms need to pay large sunk costs to start exporting [START_REF] Roberts | The decision to export in Colombia: an empirical model of entry with sunk costs[END_REF]. Thus, uncertainty over future trade policies may postpone a firm's decision to enter foreign markets. One of the main principles underlying the World Trade Organization (WTO) is the predictability of national trade policies, which would imply a reduction in uncertainty, providing a better environment to make irreversible investments.

An instrument to pursue trade policy predictability is binding tariff rates on goods, through which WTO members make enforceable commitments to do not increase applied tariffs above certain ceilings (bindings). Following the Uruguay Round in 1995, developed countries exhibited a higher share of product lines with bound tariffs than developing countries (99% versus 73%). Moreover, it is worth noting that despite tariff binding, a relevant uncertainty can still persist if the gap between bound and applied tariff (binding overhang) is relatively high. This discrepancy is quite common amongst developing countries, whereas in developed countries, applied rate and bound rate tend to be the same.

Recent studies have already highlighted that trade policy uncertainty (TPU) may affect negatively firm's export behaviour. [START_REF] Handley | Exporting under trade policy uncertainty: theory and evidence[END_REF] studies theoretically and empirically how TPU defers firm's entry in the export market (delay) and makes firms less sensitive to applied tariff cuts (caution). In particular, using product level data from Australia during 1991-2001 period, he estimates that foreign varieties' entry increases by 4% if applied tariffs are reduced to zero, and by 17% if tariffs are also bound by WTO commitments. Similar findings are also confirmed in a context of preferential trade agreements. Using firm-level data on Portuguese exports, [START_REF] Handley | Trade and investment under policy uncertainty: theory and firm evidence[END_REF] document that uncertainty reduction arising from Portugal's accession to the European Community (EC) in 1986 implied a significant increase in Portuguese exporting firms' entry to EC markets.

This paper aims at empirically exploring how trade policy uncertainty may influence firm's import behaviourrather than export behaviourgiven that previous works documented that firms also have to face large sunk costs to start importing. Therefore, we expect that the discussions above on TPU and firms' export decisions are even more pertinent for firms' import decisions, since they can imply irreversible changes in production technology, through incorporating foreign intermediate inputs.

Using Chinese (ordinary) trade transaction data during the period 2000-2006, we explore how tariff binding, arising from China's accession to WTO in December 2001, affects imports at the product level. We first make a country-related analysis, differentiating the product-level import value between the number of country-varieties (country-extensive margin) and the average imports per country-variety (country-intensive margin), focusing especially on the former margin, to check whether a reduction in Chinese TPU positively affects the entry of new foreign varieties in China.

In line with [START_REF] Handley | Exporting under trade policy uncertainty: theory and evidence[END_REF]'s findings, our results suggest that following tariff binding, Chinese economy is able to access a greater range of foreign varieties, especially from developed countries, which are typically associated with high-quality. However, we find different results across product groups discerned according to their end use, suggesting that while worldwide firms' decisions to supply final and intermediate goods to China tend to be delayed by China's TPU; their decisions to supply capital goods actually are brought forward. Moreover, while consumers benefit from a greater variety of all foreign final varieties; firms would enjoy the access to both greater variety and higher quality of intermediate varieties.

Next, we carry out a firm-related analysis, differentiating the product-level import value between the number of importing firms (firm-extensive margin) and the average imports per firm (firmintensive margin), focusing more on the former margin to see whether a reduction in Chinese TPU positively affects the entry of new Chinese firms in the import market. We document that tariff binding leads more firms to start importing a given product. This effect is confirmed for both production firms and trade intermediaries, and suggests that more Chinese manufacturing firms are able to import directly or indirectly foreign intermediate inputs, and therefore enjoy potential productivity gains from TPU reduction. In other words, it seems that TPU tends to delay firm's decision to import intermediate inputs. At the same time, we also find that TPU would hasten firm's decision to import capital goods. Finally, it appears that tariff binding pushes more foreign-owned manufacturing firms located in China to import intermediate inputs under ordinary trade regimethrough which they are not obliged to re-exporting as in the case of processing trade regimeand more foreign-owned intermediaries to be involved in importing final varieties. These results suggest that FDI in China start becoming relatively more market-seeking than resource-seeking following Chinese TPU reduction: i.e. foreign multinationals tend to relocate relatively more the downstream stages of global value chains, rather than the upstream stages in China. This work is complimentary to two recent studies on trade policy uncertainty and export behaviour in China, carried out respectively by [START_REF] Handley | Policy Uncertainty, Trade, and Welfare: Theory and Evidence for China and the United States[END_REF] [START_REF] Feng | Trade Policy Uncertainty and Exports: Evidence from China's WTO Accession[END_REF]. [START_REF] Handley | Policy Uncertainty, Trade, and Welfare: Theory and Evidence for China and the United States[END_REF] show theoretically that TPU reduction can lead more firms start exporting and more incumbent exporters upgrade their technology, implying an increase in both number of exporters and the average exports per firm. Then, using 6-digit product level data on Chinese exports to US, they show that uncertainty reduction arising from China's accession to WTO in 2001 implied a significant growth in Chinese exports to US market in the period 2000-2005[START_REF] Feng | Trade Policy Uncertainty and Exports: Evidence from China's WTO Accession[END_REF] also study theoretically and empirically how Chinese exports to US are affected by reducing trade policy uncertainty following China's accession to WTO. More specifically, by using Chinese firm-product level data, they show that TPU reduction lead the entry of new firms in the export market, and the exit of some incumbent exporters. They also demonstrated that export-starters were associated with lower prices and higher quality than exportstoppers. 2 Unlike both studies, we focus on Chinese firm's import reaction to domestic TPU reduction in a context of multilateral trade rather than on Chinese export reactions to foreign TPU reduction in a context of bilateral trade (US-China), by exploiting the time-varying binding status of product lines rather than the binding overhang. It is worth noting that while our country-related results approximately confirm their findings, i.e. that a foreign country's TPU reduction leads more domestic varieties to enter the international market, which are mostly associated with higher quality, our firm-related analysis provides new interesting insights from import perspective in a context of global value chains. 3 The rest of the paper is organized as follows. Section 2 describes the data used, giving information also about the context. Section 3 sets up the empirical strategy to explore the product level linkage between imports and trade policy uncertainty. Section 4 discusses the results, and Section 5 provides conclusion remarks.

2 [START_REF] Mau | US policy spillover(?) -China's accession to the WTO and rising exports to the EU[END_REF] shows that a reduction in US tariff uncertainty following China's WTO accession also positively affected China's exports to the European Union. 3 Pierce and Schott (2016) already provide some evidence, amongst other results, that a reduction in domestic TPU can determine an increase in the number of importing firms at home, in addition to an increase in the number of exporting firms abroad. However, their work mainly focuses on the employment effects of a one-time change in domestic TPU in a developed country within a context of a bilateral trade relationship. In particular, they document that following a reduction in US's TPU respect to Chinese imports, arising from China's accession to WTO, led to relevant employment losses in US, in addition to higher imports from China.

Data

The analysis is based on a balanced panel of 4,090 6-digit HS manufacturing product lines during the period of 2000-2006. Import data are from the database of Chinese Customs Trade Statistics (CCTS), managed by the General Administration of Customs of China; applied tariff data are from the World Bank's World Integrated Trade Solution (WITS) database; and bound tariff data are from WTO's Consolidated Tariff Schedules database (CTS). We have also included data on nontariff trade barriers (NTBs) from China's Protocol of the WTO accession available on the WTO's website.

The CCTS database contains all China's monthly trade transactions, but we focus only on imports.

For each firm-product-country level import flow, the database provides information on total value, FOB unit value (in US dollars), quantity, and trade regime. It is also possible to distinguish firms according to their macro-sector statusi.e. between producers and trade intermediariesand ownershipi.e. between foreign-owned (FORs) and domestic-owned firms, which are further split in state-owned (SOEs) and private-owned companies (DPRIVs). Since the main purpose of the paper is to investigate how tariff binding affects imports at the product-level, we dropped all observations concerning a specific trade regime different from the ordinary trade regime and collapsed the data at the 6-digit HS product-year level. Subsequently, the import data were merged with product-level data on applied tariffs, bound tariffs, and NTBs, and all observations where applied tariff was missing were dropped. Finally, we restricted our sample to the balanced panel of product lines.

Product-level Imports

Table 1 shows that a product on average exhibited an import value around 17.3 USD million in 2000, and was imported from 13 countries (country-extensive margin) with an average import value per country around 1.1 USD million (country-intensive margin), and by 104 Chinese firms (firm-extensive margin), with an average import value per firm around 0.34 USD million (firmintensive margin). It is worth noting that the two-thirds of source countries were from OECD area.

Moreover, about two-thirds of importing firms were producers, mostly foreign-owned and state-owned firms, whereas the remaining share were trade intermediaries, almost exclusively stateowned firms.

During the period 2000-2006, the product-level import value drastically increased (by about 38.6 USD million), due to both country-related intensive and extensive margins. More specifically, a product was on average imported from additional three developed countries and three developing countries, which suggests an increase in variety of both high-quality goods and low-quality goods. 4Import growth was also due to an increase in both firm-related intensive and extensive margins. In particular, the increase in the number of importing firms concerned relatively more producers than intermediaries. More specifically, a product on average seems to be imported by more additional private-owned producers (especially FORs) and private-owned trade agents (almost exclusively DPRIVs) and less by state-owned trade agents. These changes confirm the extension of trading rights to all firms, following China's accession to WTO, which allowed more easily both producers and final consumers located in China to access foreign varieties.

When distinguishing across product categories according to the end use, we can notice that the values documented above concern relatively more intermediate goods, as they represent the majority of product lines.5 However, similar patterns are found for both final and capital goods, with slightly different magnitudes. Thus, more private-owned manufacturers located in China become able to access directly or indirectlythrough the increasing presence of private trade intermediariesa greater variety of both high-quality and low-quality foreign inputs following TPU reduction. This means that they can enjoy potential productivity gains and quality upgrading effects, implying an increase in consumers' welfare. At the same time, Chinese consumers also obtain a greater access to foreign final varieties of both high-quality and low-quality, implying additional potential welfare gains. Finally, it is worth noting that while the presence of state-owned intermediaries drastically fell in importing all product categoriesespecially, intermediate and capital goodsthe number of state-owned importing producers slightly decreased for only final goods, and even increased for capital goods.

Trade policy reforms

During the 1990s, China started to implement relevant unilateral measures of trade liberalization in order to become WTO member on December 11, 2001. Through the WTO accession protocol, China committed to apply the MFN duties to all WTO members, to bind and further reduce all tariff rates, to remove several non-tariff barriers, and to extend the trading rights to all firms.

According to WTO's China Trade Policy Review (2006), China was implementing seriously all commitments, as scheduled by the protocol.

China's accession to WTO implied not only less uncertainty in exporting to China for World-wide firms, but also a decline in uncertainty in importing for Chinese firms from the rest of the World.

It is worth noting that TPU uncertainty reduction occurred at the same time for all products exported from China, as becoming WTO member in 2001, China automatically benefitted from the existing binding status of all WTO members' tariffs. Conversely, reduction in TPU uncertainty occurred in different years for products imported by China, as it was required to gradually bind all tariffs across products over time.

According these WTO commitments, China bound tariffs for all product lines, but the year of ultimate implementation can be different across products along ten-year period after becoming WTO member. This means that the applied tariff was still allowed to be higher than the final bound tariff until the last year of scheduled implementation. This would benefit relatively more the domestic downstream firms (and foreign upstream firms), as the number of foreign input varieties available will increase relatively more than the number of foreign competing final varieties. In other words, productivity gains from input varieties within downstream firms might be relatively larger than potential market shares losses arising from tougher foreign competition.

Empirical strategy

This section aims at exploring the product-level linkage between imports and trade policy uncertainty, by accounting also for changes in applied tariffs. Our baseline specification is given by:

ln(𝑀 𝑝𝑡 ) = 𝛽 1 𝐵𝑖𝑛𝑑𝑖𝑛𝑔 𝑝𝑡-1 + 𝛽 1 𝑇𝑎𝑟𝑖𝑓𝑓 𝑝𝑡-1 + 𝐷 𝑝 + 𝐷 𝑡 + 𝜀 𝑝𝑡 (1)
where Mpt stands for the import outcome for product p and year t; Bindingpt-1 is a dummy variable taking value one if the product p is subject to the ultimate bound tariff in year t-1, and zero otherwise; Tariffpt-1 represents the simple average of applied MFN tariff rate of product line p in year t-1; 𝜀 𝑝𝑡 is the classical error term. Notice that we also include both product and year fixed effects to control time-invariant product characteristics and common macroeconomic shocks across products. In subsequent specifications, we also include additional control variables, i.e. dummy variables that reflect the presence of non-tariff import barriers (NTBs) for each product p in a given year t. 7 All standard errors are corrected for clustering at the product level. Notice that our explanatory variables are lagged by one year respect to the dependent variable as import reactions to trade policy changes may be not immediate. Moreover, reverse causality problems are reduced, although several works documented that trade policy reforms in China, especially during the WTO accession period, were unlikely to be endogenous, as China's willingness to become a market economy was going beyond the interests of specific groups [START_REF] Branstetter | China's embrace of globalization[END_REF]). 8

Indeed, CTPR (2006) documents that China was able to implement all trade policy reforms, as scheduled by the WTO accession Protocol, including tariff binding.

7 NTB variables are: quotapt -1 is a dummy variable taking value one if the product p includes at least one 8-digit-HS product subject to the import quota in the year t-1; tenderingpt-1 is a dummy assuming value one if the product p includes at least one 8-digit-HS product subject to import tendering in the year t-1; and licensept-1 is a dummy variable taking value one if the product category p includes at least one 8-digit-HS product subject to the import license only in the year t-1. All NTB variables are based on the information from the WTO accession protocol of China. 8 Several empirical studies showed that changes in tariffs or non-tariff barriers were quite exogenous in China, i.e. unlikely to be influenced by sectors' performance or lobbying activities [START_REF] Brandt | WTO Accession and Performance of Chinese Manufacturing Firms[END_REF][START_REF] Bas | Input-trade liberalization, export prices and quality upgrading[END_REF][START_REF] Imbruno | China and WTO liberalization: Imports, tariffs and non-tariff barriers[END_REF].

Results

This section shows the results related to the specification (1), by analysing alternatively the country-related margins and the firm-related margins of imports (in Section 4.1, and 4.2, respectively). We first explore how home TPU influences the number of country-varieties available within each product line and/or the average imports per country-variety. Then, we also investigate whether domestic TPU also affects the number of importing firms within each product line and/or average imports per firm.

Country-analysis of product-level imports and trade policy uncertainty

Following the previous discussions on how foreign trade policy uncertainty affects export value and their margins, we expect that a reduction in Chinese trade policy uncertainty should allow China to increase its imports, through an increase in both the number of imported varieties and the average imports per variety, due to the presence of sunk costs faced by foreign exporters [START_REF] Handley | Exporting under trade policy uncertainty: theory and evidence[END_REF][START_REF] Handley | Policy Uncertainty, Trade, and Welfare: Theory and Evidence for China and the United States[END_REF].

It is worth noting that in our context, a foreign variety refers to 6-digit product/origin country pair, as Handley (2014)'s approach. Consequently, when distinguishing the product-level import value in the number of imported varieties and the average imports per variety, we are essentially disentangling between the number of origin-countries (country-extensive margin) and the average imports per origin-country (country-intensive margin).

The first three columns of Table 3 show that tariff binding has a positive effect on product-level import value (by about 6.6%), through an increase in both country-intensive and country-extensive margins (by about 5.3% and 1.4%, respectively). Thus, domestic TPU reduction allows Chinese economy to access additional foreign varieties, as well as purchase more of each foreign variety.

The results on country-intensive margin are coherent with and complimentary to Handley and Limão (2017)'s findings, which document that product-level Chinese export value to US drastically increased following a reduction in US trade policy uncertainty. It is worth noting that, like in their evidence, we are not sure whether the domestic TPU reduction really implies the entry of new firmvarieties from a foreign country, as we cannot disentangle the number of firms exporting to China, and their average export sales. However, unlike [START_REF] Handley | Policy Uncertainty, Trade, and Welfare: Theory and Evidence for China and the United States[END_REF] that focus on US's bilateral imports from China, we consider China's multilateral imports from all countries, therefore we are able to show further that a reduction in home TPU entails an increase in the number of source countries at the product-level, which reflects without any doubt the entry of new imported firm-varieties to the domestic market. Therefore, our results also confirm other studies' findings that focus more on the firm-extensive margin of exports, which document that a foreign TPU can delay firm's decision to export [START_REF] Handley | Exporting under trade policy uncertainty: theory and evidence[END_REF][START_REF] Handley | Trade and investment under policy uncertainty: theory and firm evidence[END_REF]. Applied tariff liberalization effect on import value and the related margins is also positive and statistically significant, coherently with our expectations. These results are robust when including non-tariff trade barriers (NTBs) dummies as additional controls, as displayed in columns 4-6.

In the last two columns (7 and 8), we focus on the extensive margin by discriminating between OECD and non-OECD countries, to see whether TPU effect concerns relatively more suppliers from developed or developing economies. We expect that tariff binding has a larger effect for the former countries, as China was more likely to be involved in a tariff war with advanced economies (such as US and EU) rather than with developing countries. Indeed, our results show that while a reduction in applied tariff leads an increase in the number of country-varieties from both OECD and non-OECD areas, tariff binding allows the access to a greater number of OECD-varieties only.

To the extent that products from OECD are associated with higher quality, we can reach the conclusion that a reduction in home trade policy uncertainty leads China to access more varieties of high quality. These results are therefore coherent with and complementary to Feng, et al.

(2017)'s findings, which document that TPU reduction arising from China's accession to WTO implied an increase in quality of Chinese exported varieties. Combining our results with theirs, it is possible that trade policy uncertainty reduction allowed Chinese firms to upgrade the quality of their exported varieties, through improving the access to high-quality goods from abroad, either imported final varieties (learning/competition channel) or intermediate varieties (input channel).

In Table 4, we discriminate the tariff binding effect between final goods, intermediate goods and capital goods, following the BEC classification. First, the effects documented above are strongly confirmed for intermediate goodseven with a larger magnitudeand slightly less evident for final goodsas when splitting the extensive margin between OECD and non-OECD, tariff binding's coefficients become statistically non-significant. Therefore, while Chinese final consumers seem to enjoy greater variety of foreign final goods owing to tariff binding, Chinese producers seem to benefit from both greater variety and better quality of foreign intermediate inputs. These results would suggest that potential quality upgrading of Chinese exported varieties was more likely to occur through the improved access to high-quality intermediate varieties, rather than learning/competition effects from high-quality competing final varieties. Interestingly, we find opposite results for capital goods, tariff binding implies a decline in productlevel imports, in terms of both intensive and extensive margins, and the reduction in variety of foreign capital goods concerns both OECD and non-OECD areas. This dissimilarity respect to the other BEC product categories may be linked to the difference in the nature of goods: while the consumption in foreign final and intermediate goods requires importing periodically and systematically every year, the consumption of capital goods is associated with less import frequency, since capital goods are long-run investments. Therefore, it seems that China's trade policy uncertainty tended to delay World-wide firms' decisions to export final and intermediate goods to China, and hasten their decisions to export capital goods.

Firm-analysis of product-level imports and trade policy uncertainty

Previous literature well documented that the access to foreign intermediate inputs enhances firm productivity, through variety, quality and learning channels [START_REF] Schor | Heterogeneous productivity response to tariff reduction. Evidence from Brazilian[END_REF][START_REF] Amiti | Trade Liberalization, Intermediate Inputs, and Productivity: Evidence from Indonesia[END_REF]Konings, 2007, Goldberg, et al. 2010). More recent works highlighted that only a small number of firms are able to import intermediate inputs because of large sunk fixed costs of importing [START_REF] Kasahara | Does the use of imported intermediates increase productivity? Plant-level evidence[END_REF][START_REF] Kasahara | Productivity and the Decision to Import and Export: Theory and Evidence[END_REF]. Similar discussions are valid not only for producers involved in importing intermediate goods, but also for other kinds of firms (trade intermediaries)

and goods (capital and final goods). Indeed, manufacturing firms may use both capital goods and final goods from abroad as inputs in their production process, and trade intermediaries can also face some sunk fixed costs of importing intermediate goods, final goods, and capital goods on behalf of both producers and final consumers.

Thus, this section aims at exploring whether tariff binding affects product-level import value, through the number of importing firms (firm-extensive margin) and the average imports per firm (firm-intensive margin). As regards the former margin, we also check whether there is any firm heterogeneity linked to the macro-sector status and the ownership status: i.e. whether tariff binding differently affects the number of importing producers and importing intermediaries, as well as the number of state-owned firms, foreign-owned firms and private-domestic-owned firms involved in import activities.

The columns 1-3 of Table 5 show that tariff binding positively affects product-level import value (by about 6.6%), through an increase in both firm-intensive and firm-extensive margins (by about 3.7% and 3.0%, respectively). Thus, Chinese TPU reduction allows more Chinese firms to enter the import markets, as well as more foreign purchases per (incumbent) importing firm. Similar effects are found from a reduction in applied tariffs, coherently with our expectations. These results are robust to the inclusion of NTB controls (columns 4-6).

When discriminating the extensive margin by considering the macro-sector of firms, i.e. between the number of importing producers and the number of importing intermediaries, we can see that both TPU reductions and applied tariff cuts generate positive effects for both firm groups. Furthermore, intermediate goods seem to be imported by more producers (i.e. SOEs and FORs) and more intermediaries (i.e. SOEs and PRIVs), while final goods are imported by more trade agents (i.e. FORs) and less domestic producers (i.e. SOEs and PRIVs). These results further confirm that: a) more manufacturing firms are able to import directly or indirectly foreign intermediates, and therefore enjoy potential productivity gains; b) more foreign multinationals tend to be market-seeking rather than simply resource-seeking in China (considering the drastic increase in both inward FDI in manufacturing firms associated with importing intermediate inputs under ordinary regime, and inward FDI in distribution firms associated with importing final goods). Finally, the considerations made on imports of capital goods actually concern only domestic firms (i.e. domestic-private owned producers and state-owned trade agents), given that more foreign firms (both producers and trade agents) buy foreign capital goods following TPU reduction.

Conclusion

Trade policy uncertainty (TPU) plays an important role in firm's decisions to trade. Recent works have already stressed that firms face sunk fixed costs of exporting, and showed that reducing the fear that trade tariffs may suddenly increase without any limit, firms have more incentive to start exporting. Unlike the existing literature, we focus on import rather than export behaviour, considering that firms also need to pay sunk fixed costs of importing foreign goods, so that TPU reduction may affect firm's decisions to be involved in different stages of global value chains.

Analysing product-level Chinese import adjustments to tariff binding during the period 2000-2006, as scheduled by the China's WTO accession protocol (entered in force in December 2001), our baseline results show that Chinese economy can access more foreign varieties, especially from developed countries, which are typically associated with high-quality. We have also found that tariff binding leads foreign products to be imported by more Chinese firms, involved in either manufacturing production or trade intermediation services, extending potential gains from imports amongst more producers and final consumers located in China.

We have also documented heterogeneity across products associated with different end-use. Our findings suggest that tariff binding in China allows more manufacturing firms to access a greater variety of intermediate inputs, associated also with high-quality, which could partially explain productivity gains and quality upgrading from trade liberalization documented by former evidences. However, we find opposite results when considering capital goods, which suggest that TPU tends to delay firm's decision to import intermediate inputs, and hasten firm's decision to import capital goods.

Finally, our results highlight that tariff binding pushes more foreign-owned firms located in China to being more market-seeking, rather than resource-seeking. In other words, a decline in Chinese TPU allows multinationals to relocate relatively more the downstream stages of global value chains in China, rather than the upstream stages.

These new stylized facts may represent a call for more future research on trade policy uncertainty and firm's import behaviour, to further explain potential welfare gains from reducing trade barriers.

Table 1 -Imports in China over the 2000-2006 period All products Product categories by BEC classification

 1

		FINAL	INTERMEDIATE	CAPITAL
		GOODS	GOODS	GOODS
	(N=4090)	(N=1044)	(N=2613)	(N=610)

Notes: Values are expressed in USD millions. Source: Author's calculations using data on import transactions under ordinary trade regime from the database of Chinese Customs Trade Statistics (CCTS) managed by the General Administration of Customs of China.

Table 2 -Tariff policy reforms in China over the 2000-2006 period: Tariff binding and Applied tariffs

 2 It is worth noting that while tariffs on final goods constantly decreased over time until 2005 and then remained constant, the decline of tariffs on both intermediate goods and capital goods was more evident upon WTO accession in 2002. Therefore, coherently with the previous discussion, it seems that protection through applied tariffs drastically decreases upon China's WTO accession relatively more for intermediate good production than the final one at home.

		2000	2001	2002	2003	2004	2005	2006
	Applied tariff
	All goods	0.162	0.151	0.118	0.108	0.099	0.095	0.095
	Final goods	0.252	0.229	0.195	0.177	0.159	0.150	0.150
	Intermediate goods	0.135	0.126	0.097	0.089	0.082	0.079	0.079
	Capital goods	0.152	0.147	0.102	0.092	0.086	0.085	0.085
	Binding
	All goods	0	0	0.573	0.659	0.835	0.971	0.974
	Final goods	0	0	0.326	0.376	0.673	0.992	0.992
	Intermediate goods	0	0	0.660	0.727	0.865	0.962	0.967
	Capital goods	0	0	0.543	0.764	0.938	0.980	0.980

Notes: Both applied tariff rates and the shares of product lines subject to binding are expressed in decimals. Source: Author's calculations using data on MFN applied tariffs from World Bank's WITS database, and bound tariff data are from WTO's Consolidated Tariff Schedules database.

As regards applied tariffs, intermediate goods exhibited the lowest applied tariff rate in 2000 (13.5%), followed by capital goods (15.2%), whereas final goods had the highest tariff rate (25.2%). However, all BEC categories declined their tariff rates, almost halving their initial levels in 2006.

Table 3 -Product-level import changes from tariff binding: country-extensive and country-intensive margins

 3

	Dependent variables	Value of	Average	Number of	Value of	Average	Number of	Number of	Number of
	(log) at time t	imports	value of	countries	imports	value of	countries	OECD	non-OECD
			imports per			imports per		countries	countries
			country			country
		(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
	Binding t -1	0.066***	0.054***	0.013**	0.066***	0.053***	0.014**	0.017***	0.005
		(0.020)	(0.019)	(0.006)	(0.020)	(0.019)	(0.006)	(0.006)	(0.009)
	Tariff t -1	-0.910***	-0.446*	-0.463***	-1.016***	-0.585**	-0.431***	-0.570***	-0.318***
		(0.285)	(0.248)	(0.090)	(0.293)	(0.250)	(0.090)	(0.090)	(0.118)
	NTB dummies	NO	NO	NO	YES	YES	YES	YES	YES
	Product Fixed Effects	YES	YES	YES	YES	YES	YES	YES	YES
	Year Fixed Effects	YES	YES	YES	YES	YES	YES	YES	YES
	Observations	24,540	24,540	24,540	24,540	24,540	24,540	24,360	23,218
	R-squared	0.211	0.146	0.172	0.212	0.148	0.174	0.097	0.184
	Number of 6-digit	4,090	4,090	4,090	4,090	4,090	4,090	4,087	4,071
	products

Notes: Standard errors (in parentheses) are corrected for clustering at the product level. Significance at *** p<0.01, ** p<0.05, * p<0.1. Sources: Author's calculations using data from the database of Chinese Customs Trade Statistics (CCTS) managed by the General Administration of Customs of China; World Bank's WITS database; WTO's Consolidated Tariff Schedules database and China's Protocol of the WTO accession available on the WTO's website.

Table 4 -Country-extensive margins of imports and tariff binding: final, intermediate, and capital goods

 4 Standard errors (in parentheses) are corrected for clustering at the product level. Significance at *** p<0.01, ** p<0.05, * p<0.1. Sources: Author's calculations using data from the database of Chinese Customs Trade Statistics (CCTS) managed by the General Administration of Customs of China; World Bank's WITS database; WTO's Consolidated Tariff Schedules database and China's Protocol of the WTO accession available on the WTO's website.

	Dependent variables	Value of	Average value of	Number of	Number of	Number of
	(log) at time t	imports	imports per country	countries	OECD	non-OECD
					countries	countries
		(1)	(2)	(3)	(4)	(5)
	Binding t -1 *Final good	0.089***	0.070**	0.018*	0.015	0.023
		(0.033)	(0.030)	(0.011)	(0.011)	(0.015)
	Binding t -1 *Intermediate good	0.130***	0.102***	0.028***	0.031***	0.006
		(0.024)	(0.022)	(0.008)	(0.008)	(0.011)
	Binding t -1 * Capital good	-0.199***	-0.156***	-0.044***	-0.031***	-0.029*
		(0.035)	(0.032)	(0.011)	(0.011)	(0.016)
	Tariff t -1	-1.093***	-0.643**	-0.450***	-0.601***	-0.303**
		(0.299)	(0.253)	(0.092)	(0.092)	(0.119)
	NTB dummies	YES	YES	YES	YES	YES
	Product Fixed Effects	YES	YES	YES	YES	YES
	Year Fixed Effects	YES	YES	YES	YES	YES
	Observations	24,492	24,492	24,492	24,312	23,175
	R-squared	0.218	0.153	0.176	0.099	0.185
	Number of 6-digit products	4,082	4,082	4,082	4,079	4,063
	Notes:

Table 5 -Product-level imports changes from tariff binding: firm-extensive and firm-intensive margins

 5 Standard errors (in parentheses) are corrected for clustering at the product level. Significance at *** p<0.01, ** p<0.05, * p<0.1. Sources: Author's calculations using data from the database of Chinese Customs Trade Statistics (CCTS) managed by the General Administration of Customs of China; World Bank's WITS database; WTO's Consolidated Tariff Schedules database and China's Protocol of the WTO accession available on the WTO's website.

	Dependent variables	Value of	Average value	Number of	Value of	Average value	Number of	Number of	Number of
	(log) at time t	imports	of imports per	firms	imports	of imports per	firms	producers	intermediaries
			firm			firm
		(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
	Binding t -1	0.066***	0.038**	0.029***	0.066***	0.037**	0.030***	0.028***	0.022**
		(0.020)	(0.017)	(0.008)	(0.020)	(0.017)	(0.008)	(0.009)	(0.010)
	Tariff t -1	-0.910***	-0.384*	-0.525***	-1.016***	-0.495**	-0.521***	-0.479***	-0.909***
		(0.285)	(0.218)	(0.151)	(0.293)	(0.221)	(0.155)	(0.147)	(0.192)
	NTB dummies	NO	NO	NO	YES	YES	YES	YES	YES
	Product Fixed Effects	YES	YES	YES	YES	YES	YES	YES	YES
	Year Fixed Effects	YES	YES	YES	YES	YES	YES	YES	YES
	Observations	24,540	24,540	24,540	24,540	24,540	24,540	24,322	23,970
	R-squared	0.211	0.098	0.275	0.212	0.099	0.276	0.329	0.101
	Number of 6-digit products	4,090	4,090	4,090	4,090	4,090	4,090	4,089	4,089
	Notes:

Table 6 -Firm-extensive margins of imports and tariff binding: production firms versus intermediaries firms

 6

	Dependent variables	Number of	Number of	Number of	Number of	Number of	Number of
	(log) at time t	state-owned	foreign-owned	domestic-	state-owned	foreign-owned	domestic-
		producers	producers	private-owned	intermediaries	intermediaries	private-owned
				producers			intermediaries
		(1)	(2)	(3)	(4)	(5)	(6)
	Binding t -1	0.020*	0.045***	-0.025*	0.003	0.094***	0.062***
		(0.012)	(0.010)	(0.014)	(0.011)	(0.034)	(0.015)
	Tariff t -1	-0.317*	-0.372**	-0.707***	-0.593***	0.298	-0.808***
		(0.169)	(0.153)	(0.214)	(0.174)	(0.428)	(0.220)
	NTB dummies	YES	YES	YES	YES	YES	YES
	Product Fixed Effects	YES	YES	YES	YES	YES	YES
	Year Fixed Effects	YES	YES	YES	YES	YES	YES
	Observations	21,956	23,562	19,364	23,591	5,712	18,727
	R-squared	0.095	0.348	0.678	0.185	0.532	0.739
	Number of 6-digit products	4,058	4,076	4,007	4,083	2,519	3,976

Notes: Standard errors (in parentheses) are corrected for clustering at the product level. Significance at *** p<0.01, ** p<0.05, * p<0.1. Sources: Author's calculations using data from the database of Chinese Customs Trade Statistics (CCTS) managed by the General Administration of Customs of China; World Bank's WITS database; WTO's Consolidated Tariff Schedules database and China's Protocol of the WTO accession available on the WTO's website.

Table 7 -Firm-extensive margins of imports and tariff binding: final, intermediate, and capital goods

 7 Standard errors (in parentheses) are corrected for clustering at the product level. Significance at *** p<0.01, ** p<0.05, * p<0.1. Sources: Author's calculations using data from the database of Chinese Customs Trade Statistics (CCTS) managed by the General Administration of Customs of China; World Bank's WITS database; WTO's Consolidated Tariff Schedules database and China's Protocol of the WTO accession available on the WTO's website.

		Value of	Average value	Number of	Number of	Number of	Number of	Number of	Number of	Number of	Number of	Number of
		imports	of imports per	firms	producers	state-owned	foreign-owned	domestic-	intermediaries	state-owned	foreign-owned	domestic-
			firm			producers	producers	private-owned		intermediaries	intermediaries	private-owned
								producers				intermediaries
	VARIABLES	(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)
	Binding t -1 *Final good	0.089***	0.090***	-0.001	-0.016	-0.081***	0.005	-0.047*	0.053***	-0.014	0.115**	0.023
		(0.033)	(0.028)	(0.015)	(0.017)	(0.020)	(0.019)	(0.024)	(0.017)	(0.017)	(0.057)	(0.024)
	Binding t -1 *Intermediate good	0.130***	0.064***	0.066***	0.054***	0.072***	0.030**	0.010	0.053***	0.038***	0.058	0.102***
		(0.024)	(0.021)	(0.010)	(0.011)	(0.014)	(0.012)	(0.017)	(0.012)	(0.013)	(0.039)	(0.019)
	Binding t -1 * Capital good	-0.199***	-0.144***	-0.055***	0.003	-0.017	0.159***	-0.103***	-0.136***	-0.097***	0.245***	-0.003
		(0.035)	(0.028)	(0.017)	(0.017)	(0.021)	(0.019)	(0.027)	(0.019)	(0.019)	(0.071)	(0.031)
	Tariff t -1	-1.093***	-0.487**	-0.606***	-0.552***	-0.490***	-0.359**	-0.795***	-0.943***	-0.670***	0.427	-0.906***
		(0.299)	(0.221)	(0.163)	(0.153)	(0.173)	(0.155)	(0.217)	(0.200)	(0.182)	(0.438)	(0.228)
	NTB dummies	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
	Product Fixed Effects	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
	Year Fixed Effects	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES	YES
	Observations	24,492	24,492	24,492	24,274	21,914	23,531	19,339	23,924	23,545	5,706	18,713
	R-squared	0.218	0.103	0.280	0.332	0.100	0.351	0.679	0.107	0.188	0.534	0.740
	Number of 6-digit products	4,082	4,082	4,082	4,081	4,050	4,068	3,999	4,081	4,075	2,518	3,972
	Notes:

Previous studies have highlighted that varieties from developed countries are more likely to have a higher quality than varieties from developing countries[START_REF] Bas | Input-trade liberalization, export prices and quality upgrading[END_REF].

More specifically,

64% of product lines are classified as intermediate goods, while final goods and capital goods represent only 21% and 15%, respectively.

BEC stands for Broad Economic Classification, which distinguishes goods considering their end-use in final goods, intermediate goods and capital goods.

Acknowledgments

The author would like to thank the participants at the CSAE Conference 2018 (Oxford), the ETSG 2017 Conference (Florence), the 11th International Conference on the Chinese Economy (Clermont-Ferrand), and the 67th AFSE Meeting (Paris) for their helpful comments and suggestions.

This work was supported by the LABEX IDGM+ (ANR-10-LABX-14-01) within the program "Investissements d'Avenir" operated by the French National Research Agency (ANR). : http://www.cerdi.org/

However, it is worth noting that while tariff liberalization benefits drastically more the entry of trade intermediaries to the import market than producers, tariff binding impact is slightly larger for the latter firms (2.8% versus 2.2%), suggesting that manufacturing firms have more incentive to start directly importing following TPU reduction. This is not surprising, as trade intermediaries are usually less-risk averse than producers, due to their greater diversification of the import markets across sectors and countries.

When exploring the ownership status in Table 6, we can see that the positive binding effect is confirmed for both foreign-owned (with even larger magnitude) and state-owned producers, whereas the number of domestic-private importing producers appears to shrink following TPU reduction. In compensation, the latter would benefit relatively more from applied tariff reductions than the other producers. Therefore, it seems that foreign-owned manufacturing firms were relatively more risk-averse to start importing than domestic-private ones, and tariff binding would reallocate foreign goods from private-owned to foreign-owned producers. This might be a signal that a TPU reduction leads more foreign-owned producers located in China to serve the local market (importing more under ordinary regime), rather than simply assembling the final output for the global market (importing more under processing regime). As regards trade intermediaries, while tariff liberalization leads more non-foreign-owned intermediaries to enter the import markets (especially private ones), tariff binding allows more non-state-owned intermediaries to start importing (especially foreign ones). Thus, it seems that TPU reduction attracts more FDI in trade services sector.

When examining the end-use nature of goods (Table 7), we notice that following tariff binding, product-level import value increases through both firm-intensive and firm-extensive margins for intermediate goods only. Indeed, final good imports increase only through the intensive margin, whereas capital good imports decrease through both margins. Therefore, it seems that TPU reduction allows more Chinese firms to enjoy potential gains from trade in intermediate inputs, reducing however potential gains from importing capital goods across firms. These results confirm the hypothesis that TPU tends to postpone firm's decision to purchase foreign intermediate inputs and brings forward firm's decision to invest in foreign capital goods.


D Delbergue
email: dorian.delbergue.1@ens.etsmtl.ca

D Texier

M Lévesque

P Bocher

Comparison of Two X-Ray Residual Stress Measurement Methods: Sin 2 ψ and Cos α, Through the Determination of a Martensitic Steel X-Ray Elastic Constant

Keywords: X-Ray Diffraction, Residual Stresses, X-Ray Elastic Constant, Single Exposure

X-ray diffraction technique for residual stresses measurement is usually associated to the sin 2 ψ method, a method based on the interception of the diffraction cone and line detectors. To overcome this loss of information, the cos α method is an alternative method which uses a single exposure to collect the entire diffraction cone via a 2D detector. The present paper compares both sin 2 ψ and cos α methods, through the X-ray elastic constant (XEC) determination of a quenched and tempered martensitic steel. The full-cone measurement method demonstrates a smaller scatter and a better repeatability of the measurements. This latter point is of considerable interest since larger scatter in XEC may result in large variation in residual stress values, especially at high stress levels.

Introduction

Aerospace, automotive, and power industries are constantly looking for means to improve fatigue life. Many surface-treatment processes, such as laser peening or shot peening, are known to improve fatigue life due to introduction of near-surface compressive residual stresses. However, the relationship between processes and fatigue life improvement is not fully understood. These surfacetreatment processes introduce a residual stress profile in a shallow region beneath the surface which may delay the crack nucleation and/or propagation. Therefore, residual stresses are more and more accounted for fatigue life prediction models. Consequently, it is of major concern to assess residual stresses with the best possible accuracy. Many characterization techniques, such as hole-drilling, Xray diffraction (XRD), or ultrasonics, have been developed during the last century to measure them.

X-ray diffraction technique has been widely used in industries and laboratories for residual stresses measurement. The XRD technique is based on the measurement of the crystallographic lattice deformation. According to Bragg conditions, a change in lattice spacing induce a shift of the diffracted X-ray angle [START_REF] Cullity | Elements of X-ray diffraction[END_REF]. Then, the strain and stress can be calculated from the peak shift. For decades, the traditional sin 2 ψ method has been employed for stress calculation [START_REF] Noyan | Residual stress measurement by diffraction and interpretation[END_REF]. The dedicated diffractometer mainly use line detectors, most commonly Position Sensitive Scintillation Detectors (PSSD), in order to capture the scattered X-rays. In the case of stress-free isotropic polycrystalline material, X-rays are diffracted in all directions by the grains, giving form to a cone. The line detectors only capture a limited part of the scattered X-rays corresponding to two diffraction cone radii. In the case of plane-stress state, a minimum of two sample orientations are required for strain measurements [START_REF] Noyan | Residual stress measurement by diffraction and interpretation[END_REF].

In 1978, the cos α method was developed in Japan for stress calculation [START_REF] Taira | A method of X-ray microbeam measurement of local stress and its application to fatigue crack growth problems[END_REF]. This method, also called the single exposure method, allows stress calculation by capturing the resulting diffraction cone of a single incident X-ray beam via a 2D detector. The intersection of the diffraction cone with the area detector provides a ring named Debyer-Scherrer ring [START_REF] Cullity | Elements of X-ray diffraction[END_REF]. The introduction of new 2D photosensitive detectors, such as image plate (IP), and the development of powerful calculation algorithms, bring the cos α method up to date [START_REF] Hiratsuka | Development of measuring system for stress by means of image plate for laboratory X-ray experiment[END_REF]. Since few years, portable apparatus equipped with IP allow quick residual stress measurements using the cos α method.

The two presented XRD methods measure the elastic strain for a chosen diffraction peak corresponding to specific planes of atoms in the crystal structure. This family of planes does not necessarily have the same elastic constants than the bulk material; the latter being the expression of the average elastic behavior of all plane families. Therefore, the X-ray elastic constants (XEC) determination is needed for the chosen peak of the material subjected to X-ray residual stress measurement [START_REF] Prevey | A method of determining the elastic properties of alloys in selected crystallographic directions for X-ray diffraction residual stress measurement[END_REF]. The XEC are determined by measuring the lattice strain of given crystallographic planes using a diffractometer while the specimen is subjected to constant axial loading. A wrong XEC value may underestimate the residual stress state, leading to non-conservative fatigue predictions [START_REF] Savaria | Measuring in-depth residual stress gradients: the challeng of induction hardened parts[END_REF][START_REF] Savaria | Predicting the effects of material properties gradient and residual stresses on the bending fatigue strength of induction hardened aeronautical gears[END_REF].

The present work aims at measuring the XEC with both methods on a quenched and tempered martensitic steel, and test their accuracy and repeatability.

Stress analysis

For both apparatuses, the scattered X-rays are recorded for a specific family of planes {hkl}. When the diffraction peaks have been fitted and the corresponding Bragg's angles determined, the dspacing (also called the lattice spacing) {hkl} d can be calculated using the Bragg's law. The strain is then obtained by Eq. 1:

{hkl} {hkl} φψ 0 {hkl} φψ {hkl} 0 d -d ε = . d (1)
where {hkl} φψ ε is the measured strain for the {hkl} planes for a specimen orientation referred by the φ and ψ angles, and {hkl} 0 d is the d-spacing for an unstressed specimen, usually powder. The stress tensor is considered biaxial in the irradiated layer of material (which is about 5 μm thick in the case of steel). With the sin 2 ψ method, the traditional equation for X-ray stress measurement is given as [START_REF] Prevéy | X-ray diffraction residual stress technique[END_REF]:

{hkl} {hkl} 2 {hkl} φψ 2 φ 1 11 22 1 ε = S σ sin ψ + S (σ + σ ). 2 (2)
where ( )

{hkl} {hkl} {hkl} 2 1 2S = 1+ ν / E and {hkl} {hkl} {hkl} 1 S = -ν / E
are the XEC for the family of planes {hkl}, 11 σ and 22 σ are the stress tensor components, φ σ is the stress in the φ direction, φ and Ψ angles are defined as the in-plane direction, and the angle between specimen normal and diffraction plane normal, respectively, as shown in Fig. 1. In Eq. 2, the strain {hkl} φψ ε appears to be a linear function of 2 sin ψ . The differentiation of Eq. 2 with respect to 2 sin ψ and the isolation of φ σ lead to Eq. 3:

1 . ∂ ∂ = = ∂ ∂ {hkl} {hkl} {hkl} φψ φψ φ {hkl} 2 {hkl} 2 2 ε ε E σ 1+ ν sin ψ 1 2S sin ψ (3)
Eq. 3 shows that for the sin 2 ψ method the stress φ σ is function of the XEC, strains for different ψ angles provided by the tilt of the machine. By changing 0 ψ , the angle between specimen normal and incident X-ray beam, the ψ angle will subsequently change as they are fixed together by the Bragg's angle. In the cos α method, the strain is determined by comparing the recorded Debye ring with the perfectly circular ring from an unstressed specimen. In fact, the strain along the normal to the diffraction planes varies with the ψ angle [START_REF] Cullity | Elements of X-ray diffraction[END_REF]. As the strain affects peak location, the Debye ring is not circular for specimen under stress. Eq. 4 expresses {hkl} α ε the parameter used to calculate the stress [START_REF] Tanaka | Diffraction Measurements of Residual Macrostress and Microstress Using X-Rays, Synchrotron and Neutrons[END_REF]:

{hkl} {hkl} {hkl} {hkl} {hkl} α α π+α -α π-α 1 ε = [(ε -ε ) + (ε -ε )]. 2 (4)
where

{hkl} α ε , {hkl} π+α ε , {hkl} -α
ε , and {hkl} π-α ε are strains calculated at four points located at 90° on the Debye ring (as depicted in Fig. 1). The stress is calculated by varying α from 0° to 90° in order to cover the whole ring and is a linear function of the regression between {hkl} α ε and cos α. As a consequence, Eq. 5 is the equation providing the stress for the cos α method:

1 . = {hkl} {hkl} {hkl} α α φ {hkl} {hkl} 0 2 0 ε ε E 1 1 σ = 1+ sin2η sin2ψ cosα 1 2S sin2η sin2ψ cosα ν ∂ ∂ ∂ ∂ ( 5
)
where 2η is the Debye ring semi-angle. The data are obtained for a φ angle equal to zero to estimate the uniaxial stress.

Experiment

The comparison between the two residual stress calculation methods was performed while measuring the X-ray elastic constant of a martensitic steel. The micro-tensile specimen geometry is presented in Fig. 2c). Specimen was extracted from a rolled block and contour shapes were machined with a CNC machine. Then 1 mm thick specimen was sliced using a precision cutting machine Struers Secotom-50. It was then manually polished using SiC papers (up to grade 1200) and a jig specially designed for thin specimens, allowing keeping parallelism between the two main faces. The specimen was electropolished as suggested by the ASTM standard [START_REF] Astm | E1426-98 Standard Test Method for Determining the Effective Elastic Parameter for X-Ray Diffraction Measurements of Residual Stress[END_REF]. The final specimen thickness was 0.798 mm. A Proto iXRD diffractometer was used to collect the diffraction peaks for the stress calculation via the sin 2 ψ method, while the entire Debye ring was captured by a Pulstec μ-X360 apparatus for the cos α method. Both machines were equipped with Cr-tube (λ = 2.291 Å). The Kα doublet from {211} planes family were used due to their high Bragg's angle (2θ = 156°), providing better accuracy on strain measurement. The Pulstec machine was set so that the 0 ψ angle is equal to 33.2° to capture the diffraction cone in a measurement of 30 s. The Proto apparatus was limited to seven different incident angles between ±13° (i.e. -23.6° ≤ ψ ≤ 23.6°), so the detectors do not hit the microtensile machine. 30 exposures of 0.25 s were used for each one of the seven incident angles, resulting in a measurement time of 53 s. All diffraction peaks were fitted using Gaussian peak fitting. In order to determine the most accurate XEC, a 0.5x3 mm 2 rectangular aperture was chosen for Proto iXRD and a 1 mm diameter aperture for Pulstec μ-X360, so the larger volume of diffracting material was used for each apparatus. The stresses were first assessed using Macro 1 2 2 S = 6.50 E -6 MPa -1 calculated from the macroscopic values. The XRD measurements were repeated six times for each loading condition to test equipment repeatability.

A 5 kN micro-tensile machine, manufactured by Kammrath & Weiss GmbH, was paired up with the diffractometers in order to load the specimen in tension. Nine loading conditions were chosen from 0% to 70% of the yield strength, which has been previously determined by three macroscopic tensile tests.

Micro-tensile tests were conducted under displacement control (displacement rate of 3 μm.s -1 ) and the displacement was stopped for the various loading dwells. The specimen elongation/contraction was continuously recorded by a Keyence LS-7030M optical extensometer during the whole experiment to assess the macroscopic strain. The experimental setup with the micro-tensile machine and the laser extensometer is presented in Fig. 2a) & b) when combined with the two XRD apparatus.

Discussion and Results

Fig. 3 presents the nominal stress-strain evolution applied during the experiment using Pulstec diffractometer. The plateaus correspond to the XRD measurement periods, i.e. the six measurement repetitions. The nominal stress and strain were found to be constant during these measurement periods. The difference in applied stress between the beginning of 1 st measurement and the end of the 6 th is less than 1MPa in average, except for the highest loading condition where the load decrease by 4.3MPa. This larger difference is due to a slightly sliding of the specimen in the grip for this specific condition. Nevertheless, the difference in load does not appear to be the main parameter affecting the stress measurement in this case as the lowest stress value was not measured for the 6 th repetition. Average stresses are plotted versus applied load, and are presented in Fig. 4 for the two stress calculation methods, therefore for the two diffractometers. The error bars correspond to a 95% confidence interval calculated using the Student's law. For both graphs, the stresses measured during loading and unloading are depicted as red and blue plots, respectively. The straight solid line represents a reference line in the hypothetical case where the XEC values can be estimated with the macroscopic mechanical constants of the material. As depicted in Fig. 4a) & b), the various plots are not aligned with this reference line showing that 1 2 {211} 2 S is different from the macroscopic XEC and has to be calculated to make the data slope fit with the reference line, as proposed by Munsi et al. [START_REF] Munsi | A Method for Determining X-ray Elastic Constants for the Measurement of Residual Stress[END_REF]. The correction coefficients were found to be 1.067 for the measurements done with sin 2 ψ method and 1.139 for the measurements done with the cos α method. This lead to two XEC for the {211} family of planes: 1 2 As exposed earlier in the Stress Analysis section, the XEC should be the same for both stress calculation methods. Consequently, the XEC previously determined should not differ from one measurement method to the next. Fig. 4 shows that the discrepancy of the results is lower with the cos α method, demonstrating a higher repeatability of this measurement. This may be due to the fact that in the current study the 2D detector captures 35 times more diffraction peaks, in a single exposure, than the two line detectors. This provides more statistical data for the stress calculation. For sin 2 ψ method (Fig. 4a)), the large difference in fitting curves for the loading and unloading conditions may show a low accuracy. This may be explained by a too small ψ angle scan for the sin 2 ψ method, even if the volume irradiated was twice bigger for the Proto diffractometer.

Conclusions

The stresses measured by X-ray diffraction are in linear relation with the X-ray elastic constant. Therefore, a wrong XEC value may introduce a large bias in the measured stress. The use of a microtensile machine to stress the specimen at given macroscopic loads permits to compare the sin 2 ψ and the cos α methods for stress calculation, while accessing the XEC of the studied material. Depending on the methods used for the stress calculation, a large difference in material intrinsic constant can be found. In the present study, the cos α method via the 2D detector has shown a better measurement repeatability than the sin 2 ψ method via the line detectors.

Fig. 1 :

 1 Fig. 1: Schematic representation of a specimen and grains, specimen S and measurement φ σ

Materials 10 58Fig. 2 :

 102 Fig. 2: Experimental setups: micro-tensile machine and optical extensometer paired up with: a) the Proto iXRD apparatus, b) the Pulstec μ-X360 apparatus, and c) specimen geometry presentation (dimension are given in mm).

Fig. 3 :Fig. 4 :

 34 Fig. 3: Nominal stress and nominal strain evolution during the measurements with Pulstec apparatus.

  a 95% confidence interval for the linear regression coefficients.

Acknowledgements

The authors would like to thank the research funding from the CRIAQ project MANU508 supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).


Les algues comme aliments éthiques Projet Idealg

Méthodologie et axe de travail L'identification des consommateurs pour qui les questions environnementales sont importantes dans leur alimentation a été réalisée grâce aux études menées par AGROCAMPUS OUEST dans le cadre du projet Idealg. Ces travaux ont amené à se poser la question : « Les algues alimentaires pourraient-elles répondre aux attentes des consommateurs français en termes d'éthique ? ».

Schéma synthétisant les méthodes utilisées

Nous nous interrogeons sur les motivations qui poussent les Français à adopter ce mode de consommation alimentaire de plus en plus employé, ainsi que sur les caractéristiques des produits aux algues en termes d'éthique. Cependant, les Français ont très peu d'informations sur les algues alimentaires et leurs conditions de production. Ils connaissent peu voire pas leurs systèmes de production, leur origine, leur saisonnalité et sont méfiants vis-à-vis de la qualité de l'eau dans laquelle les algues se sont développées. Les actions de communication sont rares pour éclairer les distributeurs comme les consommateurs lors de l'achat de produits alimentaires aux algues. Quelles actions sont alors envisageables pour communiquer sur l'aspect éthique des algues ?

Contexte

Aujourd'hui, l'environnement et le développement durable sont des sujets d'intérêt pour les Français. Ils peuvent avoir une incidence sur leurs comportements de consommation alimentaire. L'éthique appliquée aux biens de consommation agroalimentaires, caractérise les valeurs relatives aux impacts sociaux et environnementaux de la production. Une « consommation éthique » -également appelée « consommation responsable » -est une consommation de biens répondant aux critères pour un développement durable.

Il y a une réelle émergence du phénomène de « consommation responsable ». Les Français recherchent de plus en plus des denrées alimentaires naturelles, bios et locales, accompagnées d'une bonne traçabilité. Les algues sont des produits de choix pour les consommateurs ayant ces attentes, puisqu'elles peuvent être produites et transformées en France, de façon écologique, durable et éthique. Face à la croissance démographique, l'augmentation de la production mondiale est indispensable pour pallier la demande alimentaire croissante tout en respectant les enjeux mondiaux de durabilité. Il semble nécessaire de trouver de nouvelles sources de protéines pour nourrir les hommes. Les insectes et les algues apparaissent des pistes intéressantes.

En matière d'éthique, il ressort de l'étude de consommation que l'aspect écologique et durable des algues alimentaires sont recherchés par les Français. Ils sont persuadés que manger des algues à la place du boeuf serait un très bon moyen de réduire leur empreinte écologique, puisque la production des algues marines alimentaires, qu'elle soit naturelle ou anthropique, ne nécessite aucun intrant. Quelles caractéristiques font des algues un aliment « éthique » ?

Pourquoi les consommateurs veulent consommer responsable

Les algues marines alimentaires et leurs systèmes de production semblent posséder de nombreuses caractéristiques nécessaires pour répondre aux besoins des consommateurs responsables. Elles sont une véritable source alimentaire durable et l'offre associée à cette production propose une grande majorité de produits locaux, bruts ou peu transformés, et de plus en plus certifiés bio.

Ressource Transformation Production

consommer responsable ? Maintenir sa santé et celle de sa famille

  La quasi-totalité de la population française est sensible aux questions environnementales et d'après les études récentes, cette sensibilité se répercute sur le comportement alimentaire des Français. En effet, ils sont de plus en plus nombreux à chercher à consommer responsable. Les motivations justifiant cet engouement sont liées à la santé, à la préservation de l'environnement et au fait d'avoir confiance en ce que l'on mange. qu'ils estiment meilleurs pour leur santé et pour l'environnement et, sont plus de la moitié à faire du « made in France » une priorité. Manger des produits locaux rassure les consommateurs sur ce qu'ils mangent et les conforte dans leur démarche de consommateur éthique.

par Avec le soutien financier de

Quelles motivations à

 Privilégier l'achat de produits respectueux de l'environnement, des produits naturels  Manger équilibré et sainement Réduire son empreinte écologique  Manger naturel, bio et local  S'orienter vers de nouvelles sources de protéines (insectes, algues, etc.)  Favoriser les protéines d'origines végétales Savoir ce qu'il y a dans son assiette  Manger des produits frais, non transformés et sans produit chimique  S'assurer d'une bonne traçabilité, privilégier le local et « made in France »  S'orienter vers des produits certifiés ou labellisés De nombreux consommateurs français considèrent que leur environnement peut avoir des conséquences sur leur santé et qu'il est préférable de faire attention au caractère naturel des aliments en privilégiant des produits frais, non transformés et qui ne contiennent pas de produit chimique. Ils sont nombreux à faire confiance aux produits labellisés Bio (AB)

  Étant donné l'intérêt des Français pour l'aspect écologique des algues et leur adéquation aux attentes de la population française en matière de consommation responsable, il paraît important de développer une communication sur les produits alimentaires aux algues. Les résultats des études font ressortir plusieurs pistes d'actions concernant la communication, pour attirer les consommateurs et valoriser les produits, mais aussi visant à rassurer et fidéliser la clientèle. Il semble également nécessaire de mieux informer les consommateurs sur les aspects éthique et durable des produits aux algues d'inspiration française.ContactMarie Lesueur • marie.lesueur@agrocampus-ouest.fr • 02.23.48.58.62 Morgane Marchand • morgane.marchand@agrocampus-ouest.fr • 02.23.48.55.30 La totalité des résultats est disponible sur le site internet du Pôle halieutique : halieutique.agrocampus-ouest.fr • Rubrique Etudes et Transfert • IDEALG Animations et dégustations : rassurer les consommateurs sur leur goût, expliquer les conditions de production des algues (accent sur leur naturalité et leur durabilité) et les modes d'utilisation des produits présenter les métiers de la filière des algues alimentaires ainsi que les conditions de production et de transformation des algues, les sites internet des acteurs ou des télévisions et tablettes en magasins  Dépliants : présenter les conditions de production et de transformation des algues alimentaires (récolte, culture, certification AB, etc.), disponibles en magasins ou fournis aux distributeurs

	Quelle communication ?
	N		D
	Abondance et Cible Objectifs	Meilleure connais-Pistes d'actions
	croissance rapide	sance de la ressource  « Made in France » : à afficher sur les produits aux algues et
		privilégier l'affichage du sigle « Produits en Bretagne »
	 Attirer les consommateurs	 Marque collective : mettre en place une marque « Algues marines de Bretagne » pour rendre visible les algues alimen-taires, en faisant le lien avec son terroir et ses producteurs et
	Communication	transformateurs
	produits Gestion durable de la  Valoriser les ressource : produits	 Indications géographiques : spécifier l'origine et le lieu de Production en Bretagne transformation des algues alimentaires sur l'emballage
	-Encadrement de la	 Certification AB : à afficher sur la face avant de l'emballage
	récolte -Mise en place d'outils	et expliquer brièvement au dos de l'emballage les conditions d'attribution de la certification
	pour limiter les impacts
	en Bretagne Nombreuses entreprises mateurs Récolte manuelle ou aquaculture sans intrant Communication magasin  Rassurer  Augmenter la visi-bilité des produits  Informer et fidéli-ser les consom- Education  Vidéos « filière » :	depuis 2009 gique (AB) possible Certification biolo-Suivi écologique et sanitaire de la qualité de l'eau (si AB)
	Suivi sanitaire (bactériologie et métaux lourds) COMPARINI Charline, LESUEUR Marie, LE BRAS Quentin, LUCAS Sterenn, GOUIN Stéphane. 2016. Quelles Majorité de produits Pour en savoir plus bruts ou peu transformés
	pistes d'actions pour impulser la consommation des algues en France ? Programme IDEALG Phase 3. Les
	publications du Pôle halieutique AGROCAMPUS OUEST n°40 à 43, 136 p.
	Atouts
	L : Local
	N : Naturel
	D : Durable
		Avec le soutien
	par	financier de


Seaweed as products "for cooking"

What target consumers?

Idealg project

Methodology and work focus

The surveys conducted by AGROCAMPUS OUEST as part of the Idealg project iden"fied consumers interested in seaweed as products "for cooking", work that resulted in the authors asking the following ques-"on: "Are seaweed food products suited to French ea+ng habits?".

Diagram summing up the methods used

French-style seaweed products are distributed on a small-scale (mainly in specialised stores) but their culinary applica+ons are extremely varied and cover all ea+ng occasions. Seaweed is not part of French consumers' ea"ng habits and, despite their keen interest in French-style seaweed products, many consumers express misgivings about adop"ng and cooking them. Who are poten"al consumers of seaweed products "for cooking" and what is the associated offering? What measures could be taken to overcome consumers' reluctance to eat seaweed?

Context

In Asia, seaweed is historically a tradi"onal source of food whereas in France, seaweed consump"on is rela"vely limited and only started to gain momentum in the 2000s. French seaweed producers and processors have developed a very wide range of products suited to French-style cuisine based on seaweed in all its forms: fresh, dehydrated, raw, cooked, prepared, etc.

French consumers are increasingly op"ng for a varied, balanced diet that pleases the senses but they also associate "ea"ng well" with "home-cooked meals". This means cooking their own meals using raw products to enjoy tasty, quality food or cooking local products or products from the garden for reassurance about the origin of the food in their plate.

According to the surveys, consumers wishing to cook and eat seaweed products are mainly well-off, highly qualified women. This profile includes current consumers of French-style seaweed products, i.e. mainly women aged 30 to 60 with medium to high income. They prefer to eat seaweed at the restaurant and some of them cook it at home. These consumers eat organic produces and regularly shop at specialised stores (organic and Asian food stores).

A number of non-seaweed consumers may also fit the profile, especially those who regularly cook their own meals and want to eat natural, fresh and/or organic food.

What seaweed-based products?

French-style raw or minimally processed products perfectly match this "home-cooked" trend and meet the expecta"ons of consumers who want to eat tasty, high-quality and convivial food, as demonstrated by their popularity amongst chefs.

These products perfectly suit simple or more sophis"cated French cuisine recipes and can be used by both beginners and more experienced cooks, for all ea+ng occasions. These products are made from seaweed species that naturally grow on Bri<any's coast and, for most of them, are harvested or cul+vated in France and processed by French companies. All these criteria match the "home-cooked meal" defini"on in full.

The French-style product range also includes a few processed seaweed products that require some kind of prepara"on. These products, like seaweed and cereal mixes, are extensions of Western-style product or meal ranges widely available in France, which means that most people know how to use and prepare them. They are easier to use than raw products, especially for inexperienced cooks and can be cooked quickly.

Consumers of products "for cooking"

• Gender: Female

• Age: 25 to 64

• Income: high

• Socio-professional category:

highly qualified

Target profiles

Consumers of products "for cooking"

• Raw or minimally processed products: dehydrated seaweed; natural and/or brined seaweed; fresh, salted seaweed; condiments and tartars

• Processed food: soups, starchy foods, fresh and dehydrated salads, ready-mix for sweet cakes

Seaweed products matching the profile

Ea+ng occasions and places

• All (including aperi"fs and a@ernoon snacks)

• Restaurants and at home Project accredited by With the financial support of

In order to meet French consumers' demand for fresh, organic food with a clear origin, French-style seaweed products "for cooking" must con"nue to be sold at delicatessens and organic food shops (chain or independent stores) and also at shops specialised in fresh products like the "Grand Frais" supermarkets in France. Another distribu"on channel could be tradi+onal fishmongers, especially for non-seaweed consumers who expect to find seaweed in these outlets.

The variety of seaweed products and the fact that they can be used in a mul"tude of cooking applica"ons mean that in-store category marke+ng can help enhance their visibility by grouping them in terms of their consump"on universe and then in categories based on their complementarity, similarity or subs"tutability.

What distribu+on channel and marke+ng?

Improving packaging

Produc+on innova+ons

• Aesthe+cs: recyclable, semi-transparent packaging with an appealing, evoca"ve graphic design and colours

• Informa+on on the back of the packaging: product composi"on, origin and name of the species, place of manufacture, and possibly the name of the producer

• Recipes and +ps: simple recipes, easy to prepare and adapted to French-style cuisine, on the back of the packaging or in a separate booklet

Plus points

⇒ Rassure Reassures consumers about the visual aspect ⇒ A<racts and informs consumers about the product and its origin ⇒ Facilitates purchase choices ⇒ Helps consumers adopt the product and cook it, alone at home

Minus points ⇒ Marke"ng investment

The visual aspect is a determining factor when deciding to buy a product. This is why improving the aesthe-"cs of the packaging of seaweed products "for cooking" is so important, as well as using it to convey informa"on.

Distribu+on channel Seaweed products "for cooking" Loca+on Promo+onal tools

Super and hypermarkets

Fresh and salted seaweed, seaweed tartars Self-service delicatessen sec"on Dehydrated seaweed, seaweed in jars, canned condiments and tartars

Grocery sec"on

Organic shops

Fresh and salted seaweed Chilled sec"on • Spo<ers

What communica+on ?

To clarify the choice for retailers when purchasing seaweed products "for cooking" and help them be<er sell edible seaweed to their customers, a number of incen"ves can be implemented by processors, if possible collec+vely, in view of the costs incurred.

Processors and retailers of seaweed products "for cooking" could also launch consumer communica"on campaigns to boost sales.

Target audience

Retailers Consumers

Objec+ves

• Train retailers • Raise consumers' awareness of seaweed and reassure them about its taste

• A<ract and inform consumers

• Promote sales

• Help consumers adopt the product and cook it alone at home

Possible measures

• Technical factsheets 1. On edible seaweed and produc"on methods 2. Specific to each processor (produc"on and offer) with "ps on how to use their seaweed products

• Cooking workshops: how to cook seaweed sessions for salespeople, small retailers , sec"on managers and shop assistants

• Hand out samples: samples of fresh or dehydrated seaweed depending on the fish or shellfish bought by customers, with "ps on how to use it

• Promo+ons and tas+ng events: proposed in store by processors and retailers

• Product informa+on and recipes: informa"on about seaweed, recipes and how to cook it

  For further informa+on COMPARINI Charline, LESUEUR Marie, LE BRAS Quen"n, LUCAS Sterenn, GOUIN Stéphane. 2016. Quelles pistes d'ac ons pour impulser la consomma on des algues en France. Programme IDEALG Phase 3. Les publica"ons du Pôle halieu"que AGROCAMPUS OUEST n°40 à 43, 136 p.ContactMarie Lesueur • marie.lesueur@agrocampus-ouest.fr • +33(0)2.23.48.58.62 Morgane Marchand • morgane.marchand@agrocampus-ouest.fr • +33(0)2.23.48.55.30

• Seaweed cooking kit containing more or less prepared seaweed products, a booklet on seaweed (produc"on, origin, seasonality, organolep"c quali"es, recipes) and a suitable cooking utensil

All the results are available on the Fisheries and Aqua"c Sciences Centre website: halieu"que.agrocampus-ouest.fr • "Etudes et Transfert" sec"on • IDEALG


Seaweed as health and diete"c food

What target consumers?

Idealg project

Methodology and work focus

The surveys conducted by AGROCAMPUS OUEST as part of the Idealg project iden"fied consumers interested in seaweed as a health food because of its nutri"onal and diete"c proper"es, work that resulted in the authors asking the following ques"on: "Is edible seaweed a health food product and is it suited to French ea"ng habits?"

Diagram summing up the methods used

Health is one of the main perceived a+ributes of edible seaweed in France. French consumers associate it with seafood as well as with a number of nutri"onal, diete"c and health benefits. When asked about the profile of seaweed consumers, both general public respondents and experts imagine a woman looking for natural, healthy and low-calorie products to help her eat be/er and watch her figure. This profile is indeed a historical one in edible seaweed consump"on; many French women, however, have never had access to such products and are therefore a poten"al target.

Besides, despite the obvious link between edible seaweed and health, few processors and retailers are marke"ng seaweed as a health product in an appropriate selling environment. Only organic shops highlight this aspect. The panel of experts also confirmed how difficult it is for them to place seaweed in a specific product category.

Context

Macro-algae have been part of the human diet from "me immemorial and have long been used in Chinese, Japanese and Indian medical schools for their medicinal proper"es. In France, consuming seaweed as food is a rela"vely recent and minority prac"ce. Consump"on started in the 1970s, spurred on by vegetarians interested in its nutri"onal proper"es, and then a+racted a larger consumer base in the 2000s with the development of Japanese restaurants and the success of sushi.

What consumers?

The results of the surveys show that the nutri"onal and/or diete"c proper"es of seaweed appeal to two consumer profiles: consumers of both health and diete"c food and consumers of health food only.

On the one hand, consumers of both health and diete"c food account for around 20% of the popula"on interviewed as part of the Idealg project. These are mainly older, re"red women. Although these people want to eat a balanced diet made up of natural and healthy products, most of them are post-menopausal and also look for food that will help them control their weight. On the other hand, almost one third of the respondents are consumers of health food only. These are men and women, aged 45 to 64, in ac"ve employment.

More than half of the people in these two main target consumer profiles do not eat seaweed. Although organolep"c proper"es are important for a majority of non-seaweed consumers, they do not appear to be a limi"ng factor when it comes to consuming seaweed-based products.

What seaweed-based products?

Health food is food with a health and/or nutri"onal claim about which a brand communicates. Diete"c food addresses specific groups of the popula"on, like young children, sportspeople or people on a slimming diet. Edible seaweed is both a health and diete"c food product because it is both high in soluble dietary fibres, vitamins, minerals and proteins and low in fat and carbohydrates.

Each seaweed species, however, has its own proper"es that vary according to the season and or/ produc"on site, and some have a higher protein, iodine or dietary fibre content than others. Many consumers are ac"vely employed and may prefer to grab a bite to eat at lunch or would rather not cook in the evening a?er a long day at work. For these people, processed seaweed-based products can offer a healthy diet whilst limi"ng the "me spent cooking.

Consumers of health and diete"c food

Consumers of health food only

Target profile

• Gender: female

• Age: 55 and over

• Gender: male and female

• Age: 45 to 64

• Marital status: single, living as a couple, as a family

• Socio-professional category: ac"vely employed or re"red Two measures are put forward to highlight the nutri"onal and diete"c proper"es of edible seaweed and make the "health" or "slimming" benefit of some of the French-style products more visible: crea"ng a "diete"c" seaweed product range and displaying a nutri"onal claim as well as healthy/diete"c recipes on the packaging.

What distribu"on channel and marke"ng?

Seaweed products intended to be eaten as health and/or diete"c food would be marketed in the same distribu"on channels as all French-style products, i.e. organic chain stores and independent organic and health food shops. These are regularly frequented by target women consumers and are rela"vely wellestablished in France.

In-store category marke"ng can also be used. This means placing "diete"c" seaweed products in the same sec"on as general "low-calorie" products. Mixed salads and fresh blended salted products would be available in the fresh produce and/or fresh snacking aisle. Fresh blended sweet products -dairy products mainly-would be sold with fresh dairy desserts. Finally, ready-made meals and canned blended products would be found in the soup, can and ready-made aisle.

To improve the visibility and iden"fica"on of seaweed products, which are s"ll quite rare in the French diet, these should be placed at eye and hand level on shelves, so that consumers can easily see and grab them, within reach of best-sellers and preferably not far from smoked fish and salmon, which go very well with seaweed.

"Diete"c" seaweed product range

Nutri"onal claim and recipes on packaging

Product innova"ons

• Fresh, low-calorie diete"c recipes suitable for women

• Blended recipes suitable for older people with chewing problems

• Packaging focussing on lowcalorie, femininity and seaweed

• Claim placed on packaging front, highly visible

• Claim briefly presen"ng the benefits for health

• Recipes (on the back)

Minus points

⇒ Diversifica"on too fine for the processor ⇒ Disrup"ve approach compared to the rest of the offering ⇒ Small target group ⇒ General nutri"onal claims subject to administra"ve control ⇒ Low-differen"a"ng marke"ng strategy ⇒ Long process

Plus points

⇒ Range suitable for women and older people, both well represented in the target groups ⇒ A+racts consumers and informs them about the product ⇒ Helps consumers adopt the product and prepare it, alone at home

In-store category marke"ng

Plus points: improves access to seaweed food products by dissemina"ng them in the different sec"ons of the store, from the fresh produce aisle to the canned food sec"on.

Minus points : makes seaweed products less visible as they are buried away among the mass of other products.

Project accredited by

With the financial support of

The results of the surveys help iden"fy a number of poten"al communica"on measures, in addi"on to those already men"oned. These measures aim to a+ract consumers, increase product value as well as reassure consumers and build loyalty. Communica"ng on the "health" and "slimming" proper"es of French -style seaweed products is possible at different levels.

For further informa"on COMPARINI Charline, LESUEUR Marie, LE BRAS Quen"n, LUCAS Sterenn, GOUIN Stéphane. 2016. Quelles pistes d'ac ons pour impulser la consomma on des algues en France. Programme IDEALG Phase 3. Les publica"ons du Pôle halieu"que AGROCAMPUS OUEST n°40 à 43, 136 p.

Contact

Marie Lesueur • marie.lesueur@agrocampus-ouest.fr • +33(0)2.23.48.58.62 Morgane Marchand• morgane.marchand@agrocampus-ouest.fr • +33(0)2. 23.48.55.30 All the results are available on the Fisheries and Aqua"c Sciences Centre website: halieu"que.agrocampus-ouest.fr • "Etudes et Transfert" sec"on • IDEALG

Objec"ves Possible measures

In schools

• Educate children about a healthy diet

• Reduce misgivings about seaweed taste and texture

• School canteen opera"ons: acquaint young children with edible seaweed and its high nutri"onal value through Tas-"ng Weeks, theme-based lunches or films and leaflets

In the media

• Provide a large audience with the same informa"on

• Disseminate informa"on about edible seaweed and its benefits

• Mul"channel communica"on campaign: use different communica"on channels (television, radio, Internet, health or women's magazines) to place adver"sements about seaweed and its benefits paid for by a professional organisa"on alone or in partnership with public authori-"es

• Mass media: convey informa"on about seaweed on TV (specialised TV programmes), the radio and the press (women's or health magazines)

At trade fairs

• Connect processors/ producers with visitors

• Trade fairs or events dedicated to health and well-being:

communicate about the benefits of seaweed products, discuss with visitors, organise product tas"ng, hand out samples to be tasted at home

In-store

• Create a link between seaweed products and consumers

• Reassure consumers about seaweed product taste and prepara"on

• Tas"ng events as part of promo"onal campaigns: instore workshops led by nutri"onists and die"cians explaining how seaweed is produced, processed and can be prepared plus a few recipes

Consumers of health and diete"c food Consumers of health food only Seaweed products matching the profile • Minimally processed food: raw

		• Cook 4 to 6 "mes a week
	Preferred	• Organic shops
	distribu"on	• Super and hypermarkets
	channels	• Fishmongers
	Project	With the
	accredited by	financial
		support of

products (mainly dried seaweed), tartars and condiments • Processed food: breads, garnishes, soups, cans • Minimally processed food: raw products (dried, fresh or brined seaweed), tartars and condiments • Processed food: breads, rille+es, garnishes, soups, cans


Guillaume Burgaud

Remi Batisse

Stéphane Hertz-Clemens

Georges Cailletaud

Yazid Madi

Gilles Rousselier

Stephane Hertz-Clemens

In-service life estimation of damaged gas pipelines : Full-scale experiments and finite element analyses

come   L'archive ouverte pluridisciplinaire

Identification of the material parameters

A series of specimens are machined in pipes from field in order to characterize the mechanical behavior. They include, smooth tensile bars, plane strain specimens and low cycle fatigue specimens. To describe the indentation process, smooth tensile bars and plane strain specimens were tested with a monotonous loading. Low cycle fatigue specimens are then used to obtain the cyclic behavior. Due to the production process of spirally welded steel pipes, the supposed anisotropy of the material was tested by testing smooth tensile bars in eight different directions defined by the angle with respect to the rolling direction ( = -26 • , 0 • , 16 • , 32 • , 48 • , 64 • , 77 • , 90 • ). Results showed a classical orthotropic behavior. Plane strain tests generated stress states that are close to the loading of a pipe under pressure. They give us information on the yield function which lies between Mises' and Tresca's. Low cycle fatigue specimens were tested after various preloading levels ( = -2%, 0%, 4%, 6%, 8%) with two strain range ( = 1%, 2%) to evaluate the influence of pre-loadings on fatigue life. Results showed that a prestrain increases the subsequent fatigue life for 0 > > 8%. Barlat's criterion [1,2] is used to account for orthotropic behavior. It introduces a stress deviator modified by a six component matrix. Three kinematic hardenings variables were also needed to describe both the cyclic behavior of low cycle fatigue specimens and mechanical response for monotonous tests made on smooth tensile bars and plane strain specimens [START_REF] Besson | Mécanique non linéaire des matériaux[END_REF]. The model is able to reproduce the difference between rolling and transverse direction in monotonic tests (Fig. 1) and the subsequent cyclic behavior after preloading (Fig. 2). This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article available at http://www.matec-conferences.org or http://dx.doi.org/10.1051/matecconf/20141206007

MATEC Web of Conferences

Finite element analyses

The current mesh of the tube, which nominal diameter is 1160 mm and thickness is 15 mm, introduces quadratic hexahedral elements, the size of which is 2 mm × 2 mm × 2 mm around the dented area. Larger elements are used for the rest of the tube. Their role is to correctly describe the global structural response in bending. The tube is reduced to a quarter due to symmetry conditions. It is maintained along the bottom line and the symmetry planes. A meshed indentor is pushed on the pipe, the indentation depth ranges are between 10 mm and 100 mm. Calculations were performed with two different shapes of indenters, a sphere (diameter 30 mm) and a dome (diameter 55 mm). The current results shows that the sphere produces more plastic strain and residual stresses than the dome (Fig. 3). The purpose of the study is to predict the influence of denting on the residual fatigue life for two cyclic pressure levels that are selected to be the minimum and maximum pressure gas pipes are usually submitted to. The life prediction models are sensitive to the mean stress and the stress amplitude [START_REF] Chaboche | Mécanique des matériaux solides[END_REF]. The influence of prestrain and residual stress is also taken into account.

06007-p.2

FDMDII -JIP 2014

Figure 1 .

 1 Figure 1. Comparison between tests and simulation for rolling and transverse directions.

Figure 2 .Figure 3 .

 23 Figure 2. Monotonic and subsequent cyclic loading in the rolling direction.