Numerical study of the near-field of highly underexpanded turbulent gas jets

For safety issues related to the storage of gases (e.g. hydrogen) under high pressure, it is necessary to determine how the gas is released in the case of failure. In particular, there exist limited quantitative information on the near-field properties of gas jets, which are important for establishing proper decay laws in the far-field. Simulations of the near-field of highly underexpanded (high pressure) gas jets have been performed using Finite-Volume solver of the CAST3M code and validated using several sources available in the literature. The numerical model solves the 3D Compressible Multi-Component Navier–Stokes equations directly without relying on the compressibility-corrected turbulence models. It provides sufficiently fair mean predictions both in the case of one-component air–air and two-component helium-air releases. Possible initial conditions for the far-field simulations are suggested in terms of distance from the source, as well as the turbulence characteristics and gas-dynamic parameters at this location. In addition, these results are used to evaluate several notional nozzle concepts in order to determine the one physically consistent.     

浅析食品道德责任对食品安全的影响

随着人民群众生活水平不断提高, 食品安全问题也越来越受到社会各界的关注。若要全面、彻底地解决食品安全问题, 不仅需要运用强有力的法制手段, 还必须要从社会道德重构方面着手。本文对当前国内食品安全社会道德责任的缺失现状进行了简要地介绍与论述, 并结合具体的案例来探索造成食品安全频频发生的原因, 最后从道德责任的角度来确定食品安全问题的解决办法, 以供相关从业人员参考、借鉴。     

Automated quantitative model-based fault diagnosistic protocol via Assumption State Differences

This treatment describes the details of a systematic protocol useful for performing optimal automated process fault analysis. This implementation generalizes the underlying Boolean logic version of the Method of Minimal Evidence (MOME) developed previously to a highly comprehensive algorithm for performing model-based fault diagnostics. This generalization allows for a more compact treatment of potential single and multiple fault situations, at all levels of possible diagnostic resolution, with both elegant and efficient uniform sensor validation and proactive fault analysis (SV&PFA) diagnostic rules for diagnosing those situations. This Assumption State Differences (ASD) Protocol version of the MOME algorithm thus automates the diagnostic reasoning necessary to continuously perform optimal process fault analysis so that only the underlying well-formulated models are required to achieve such performance. Using this algorithm consequently directly simplifies the solution of the more complicated problem of automated process fault analysis into the much more tractable, and incrementally solvable, problem of adequately modeling normal process operations.     

331省道盱眙段扩建工程梁项水库占用工程技术要点初探

331省道盱眙绕城段改扩建工程施工直接影响到梁项水库蓄水、防洪与大坝堤身安全,本文分步骤祥述了梁项水库施工占用水库库容及附属工程补偿技术要点和解决方案。     

Prevalence,acquired antibiotic resistance and bacteriocin production of Enterococcus spp. isolated from tunisian fermented food products

In this study, a total of 100 fermented food products including dairy (Lben, Rayeb, Rigouta, and Jben) olive and vegetable products, harvested in Northwestern Tunisia, were investigated for the presence of Enterococcus spp. Our results showed high levels of contamination with Enterococcus spp., identified according to standard bacteriological, biochemical and phenotypic criteria. 143 isolates were recovered; E. faecium (46.15%) was the predominant species, followed by E. faecalis (27.27%), E. casseliflavus (12.58%), E. durans (8.39%) and E. mundtii (5.59%). None of the isolates showed acquired resistance againts clinically relevant drugs used for enterococcal infections treatment in human medicins, and no haemolytic activity was demonstrated. Furthermore, over 50% of the isolates within each species exhibited antilisterial bacteriocin production. Further data are needed to enhance understanding of bacteriocin production of enterococci in fermented food products as well as the potential risks to quality and safety, including possible transmission of antibiotic resistant organisms to human consumers.     

Food safety education for people with diabetes and pregnant women: A positive deviance approach

Few education programs target audiences at high-risk for foodborne illness, especially people with diabetes and pregnant women. The objective of this study is to develop a food safety education program for each using a positive deviance approach. The positive deviance focus group is a novel educational intervention that allows participants to discuss their food handling behaviors and decide to try recommended positive practices modeled by people like themselves. To fit within the educational programs offered by the collaborating institutions, three sessions were given, discussing safe handling topics: ‘Cook and Chill,’ ‘Clean and Separate,’ and ‘Choose Safe Food.’ People with diabetes (32) and pregnant women (29) participated in the study. Focus groups were audiotaped and transcribed. Participants became involved and inspired by vivid discussions and were inspired to change their behaviors to the recommended food handling practices modeled by their peers. Safe food handling practices were reinforced by take-home tasks focused on using refrigerator and cooking thermometers and using separate cutting boards. Participants were unaware of details associated with safe handling recommendations, such as the recommended temperature for cooking specific items or the temperature of the refrigerator. Results of this study indicate that positive deviance discussion module could be a promising alternative to traditional methods of food safety education.     

Process manages and hygienic practices of local beverages producers and sellers in Ouagadougou,Burkina Faso

The trade of local beverages and ice has become popular in many developing countries including Burkina Faso. This study was performed to determine the local beverages safety knowledge of producers and sellers in Ouagadougou. Face-to-face interviews of 233 producers and sellers were conducted. The approach used concerned the process of good hygiene and production. The data were collected following observation checklists and an adapted set of questions: knowledge of risk perception, training, personal hygiene, cleanliness of the selling site, water supply, refreshment condition, packaging materials, food handling practices and foodborne pathogens. Data were analysed by using means, frequencies, standard deviation, 95% confidence interval and t-test. The results of survey showed that women represent 94% of 233 total sellers. Eighty five percent 85.4% did not receive appropriate training about food hygiene and 72.5% of them did not know the reasons of local beverages and ice contamination. Only 35.6% of the sellers used freeze system to store beverages. Poor quality of water and hands implicated to local beverage manufacturing were respectively assigned 8.6% and 7.3%. Statistical analyses revealed significant difference (P < 0.05) between hygiene training and stationary sellers (P = 0.004), hygiene training and source of water (P = 0.02), hygiene training and cold chain (P = 0.013). In view of the socio economic importance of local beverages and their role in the unexpected arrival of food-borne diseases, local beverages sellers should be regularly trained, retrained in order to prevent outbreaks of food-borne illnesses.     

The role of cooperatives in food safety management of fresh produce chains: Case studies in four strawberry cooperatives

Recent outbreaks with fresh produce have raised questions regarding management of quality and safety in the complex supply chains, where cooperatives play a central role. The overall objective of this article was to investigate the role of cooperatives in food quality and safety management in the fresh produce chain, focussing on the food safety management systems implemented on the farms. More specifically, we raise the question how a more market-like or a more hierarchy-like governance of transactions via cooperatives affect the quality and safety management system of the members. The research employed case studies in four cooperatives in Belgium and the Netherlands, each with different size and per cent of contractual sales. Data was collected with a diagnostic tool for assessment of food safety management systems (FSMS) on the farms, and semi-structured interviews with the quality assurance managers of the cooperative firms. Twenty-eight strawberry farms were assessed with the diagnostic tool, seven per each cooperative. Cooperatives play a double role in managing quality and safety in the food supply chain. They are responsible for the supply chain management, including tactical decisions about coordination of quality and safety requirements between customers, cooperative firms and their farmers. At the same time, they are selling the products of their members and make strategic decisions about the governance of transactions in the supply chain, which ultimately may have an impact on the supply chain management and the FSMS on the farms. Farmers in cooperatives with more hierarchical relationships showed better operation of control activities (score 3), and advanced assurance activities at score 4 (advanced level), more science-based, adapted and tested for their effectiveness. This was associated with more effort put in supply chain management by the cooperative to support collaboration and coordination in the chain. However, the largest cooperative had moderate scores for several key control functions, suggesting that large cooperatives with complex business functions may suffer from lower commitment of members, leading to lower FSMS performance at farms.     

4-Methylimidazole in soluble coffee and coffee substitutes

Soluble coffee and coffee substitutes' consumption has grown considerably in recent years. These products, prepared from roasted coffee and/or cereal extracts, are more consumer-friendly than plain coffee, being usually cheaper. During roasting, several toxic compounds can be produced from carbohydrate degradation in presence of aminoacids, including 4-methylimidazole (4-MeI). This work aimed to screen the presence of 4-MeI in soluble coffee and its surrogates commercialized in Portugal using a previously validated gas chromatography-mass spectrometry (GC–MS) method. In a total of 45 soluble samples analyzed, including 10 plain coffees, 8 decaffeinated coffees, 12 cereal mixtures with coffee and 15 cereal mixtures without coffee, all the samples were positive for 4-MeI, with levels that ranged from 136 to 1411 μg/kg. All cereal-containing samples had significantly higher amounts (p < 0.01) than coffee samples, whilst no statistical differences were observed between decaffeinated and plain coffees. The high variability observed between samples is not influenced by the “brand” effect as well as by raw-material.     

对自贡市建筑施工安全管理的若干思考

分析了自贡市建设主管部门面临的实际问题以及建筑工程施工安全管理存在的主要问题,并针对存在的问题探讨了相应的解决措施,包括全面落实安全生产责任制、发挥监理作用、加强建设行政主管部门监督力度等,以促进建筑行业长期稳定健康发展。