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41.
An increasing number of proficiency testing schemes (PT schemes) related to occupational and environmental health have been
organised. Most schemes emphasise the importance of the validation of analytical results. With regards to harmonisation of
the schemes, there are many differences between the schemes at many levels. These include factors concerning their relationship
with legislation, national status, type and quality of proficiency testing material, analytical range and priorities for future
development. Since differences between PT schemes have been recognised at the European level by organisers of PT schemes and
external quality assessment schemes (EQASs) it seems appropriate to reinforce collaboration between scheme organisers in order
to improve the quality of analytical performance in occupational and environmental health. 相似文献
42.
刘卓军 《数学的实践与认识》2008,38(20)
实现和谐社会需要一个与之相适应的社会分配结构.借助基尼系数描述了一种和谐的社会分配结构.通过观察和分析我国近年的经济数据可以发现,为实现和谐的分配状态,我们必须应对许多严峻挑战:城乡差别依旧过大;接近占总人口20%的最贫困人群几乎没有财富积累;过大的地下经济扭曲并影响了社会的公平分配.进行社会分配必须兼顾均衡与效率.要实现和谐的分配状态,可以有许多考虑和选择.建议采取法律、法规、科技、政策和行政的各种手段,要坚决消灭近20%最贫困人群的入不敷出的情形;要全力打造中等收入阶层;要加大取缔黑色收入规范灰色收入的力度;要加快城镇化建设的步伐;要积极营建促进全民创业的环境. 相似文献
43.
Erwin Hans Gerhard Wullink Mark van Houdenhoven Geert Kazemier 《European Journal of Operational Research》2008
We consider the robust surgery loading problem for a hospital’s operating theatre department, which concerns assigning surgeries and sufficient planned slack to operating room days. The objective is to maximize capacity utilization and minimize the risk of overtime, and thus cancelled patients. This research was performed in collaboration with the Erasmus MC, a large academic hospital in the Netherlands, which has also provided historical data for the experiments. We propose various constructive heuristics and local search methods that use statistical information on surgery durations to exploit the portfolio effect, and thereby to minimize the required slack. We demonstrate that our approach frees a lot of operating room capacity, which may be used to perform additional surgeries. Furthermore, we show that by combining advanced optimization techniques with extensive historical statistical records on surgery durations can significantly improve the operating room department utilization. 相似文献
44.
Two alternative approximating functions for representing the unknown composite residual density function of a cost-quantity frontier are examined. The frontier is one in which cost is regarded as preselected. This is appropriate for public sector economics and discretionary cost situations. One function requires the estimation of a single distribution parameter, whereas the other makes no a priori assumption on the shape of the density function. 相似文献
45.
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47.
Edyta Janik Marcin Niemcewicz Marcin Podogrocki Michal Ceremuga Leslaw Gorniak Maksymilian Stela Michal Bijak 《Molecules (Basel, Switzerland)》2021,26(13)
Mycotoxins represent a wide range of secondary, naturally occurring and practically unavoidable fungal metabolites. They contaminate various agricultural commodities like cereals, maize, peanuts, fruits, and feed at any stage in pre- or post-harvest conditions. Consumption of mycotoxin-contaminated food and feed can cause acute or chronic toxicity in human and animals. The risk that is posed to public health have prompted the need to develop methods of analysis and detection of mycotoxins in food products. Mycotoxins wide range of structural diversity, high chemical stability, and low concentrations in tested samples require robust, effective, and comprehensible detection methods. This review summarizes current methods, such as chromatographic and immunochemical techniques, as well as novel, alternative approaches like biosensors, electronic noses, or molecularly imprinted polymers that have been successfully applied in detection and identification of various mycotoxins in food commodities. In order to highlight the significance of sampling and sample treatment in the analytical process, these steps have been comprehensively described. 相似文献
48.
Most of the structural health monitoring (SHM) methods is either based on vibration-based and contact acoustic emission (AE) techniques. Both vibration-based and acoustic emission techniques require attaching transducers to structure. In many applications, such as those involving hot structural materials for thermal protection purposes or in rotating machines, non-contact measurements would be preferred because the operating environment is prohibitive leading to potential damage in contact sensors or their attachments. In this paper, a new non-contact, acoustic-based damage detection method is proposed and tested with an objective that the proposed method is able to detect the location and extend of damage accurately. The proposed acoustic-based damage detection method is a direct method. In this proposed method, changes in vibro-acoustics flexibility matrices of the damage and health structure are used to predict the location and extend of damage in the structure. A case study involving actual measured date for the case of a fixed–fixed plate structure is used to evaluate the effectiveness of the proposed method. The results have shown that the proposed acoustic-based damage detection method can be used to detect the location and extend of the damage accurately. 相似文献
49.
Essential oils (EOs) have been used for centuries, and interest in these compounds has been revived in recent years. Due to their unique chemical composition as well as antimicrobial, immunostimulatory, anti-inflammatory and antioxidant properties, EOs are used in pharmacology, cosmetology and, increasingly, in animal breeding and rearing, and processing of animal raw materials. Essential oils have become a natural alternative to preservatives, taste enhancers and, most importantly, antibiotics, because the European Union banned the use of antibiotics in metaphylaxis in animal husbandry in 2006. In the animal production chain, EOs are used mainly as feed additives to improve feed palatability and increase feed intake, improve animal resistance and health status, and to prevent and treat diseases. Recent research indicates that EOs can also be applied to sanitize poultry houses, and they can be used as biopesticides in organic farming. Essential oils effectively preserve meat and milk and, consequently, improve the safety, hygiene and quality of animal-based foods. Novel technologies such as encapsulation may increase the bioavailability of EOs and their application in the production of food and feed additives. 相似文献
50.
航空航天飞行器、风电等工程机械结构的安全性保障至关重要,复合材料等新材料的大量应用,进一步提升了对结构健康监测的难度和要求。裂纹、脱层等复合材料结构典型损伤形成机理复杂、易扩展,损伤程度累积严重时会造成结构的突然失效。面向复合材料结构的损伤监测与诊断,现有的方法大多很难实现对结构损伤程度的跟踪评估,进而无法对结构的安全性评价提供依据。采用Lamb波监测理论,基于其传播距离远、对小损伤敏感等特点,通过研究分析典型损伤对Lamb波结构响应信号传播的多个特征作用过程和机理,采用多尺度分析,提取结构损伤时频域多特征参数;借助于神经网络的非线性映射能力,构建多特征复合材料结构损伤程度评估模型,实现对不同程度下典型结构损伤的评估。在环氧玻璃纤维复合材料板结构上的实验验证结果表明:提取的Lamb波时频域多特征参数,对不同程度典型损伤有一定的敏感性,所构建的损伤程度评估系统可以较为有效的实现损伤的程度估计。 相似文献