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91.
Jinghu Hu David M. Christopher Xuefang Li 《International Journal of Hydrogen Energy》2018,43(29):13649-13658
Various reduced-order models have been developed to quickly model high pressure underexpanded jets. One example is the two-layer partitioning model which was developed to model underexpanded jets, but it has not been evaluated for high pressure jets with obstacles in the jet flow region. This research describes an improved two-layer partitioning model based on the Abel-Noble equation of state that is applied here to model horizontal jet flows impacting a vertical obstacle with validations against high pressure gas experiments, full CFD simulations and a revised notional nozzle model based on the Abel-Noble equation of state. The improved two-layer partitioning model accurately predicts the gas concentrations on the obstacle for a 15 MPa underexpanded jet while consuming much less computational resources and time compared with the full CFD simulation. 相似文献
92.
Maria Grazia Basanisi Gianfranco La Bella Gaia Nobili Rosa Coppola Annita Maria Damato Maria Assunta Cafiero Giovanna La Salandra 《International Journal of Food Science & Technology》2020,55(3):1145-1150
The authenticity and traceability of meat products are issues of primary importance to ensure food safety. Unfortunately, food adulteration (e.g. the addition of inexpensive cuts to minced meat products) and mislabelling (e.g. the inclusion of meat from species other than those declared) happens frequently worldwide. The aim of this study was to apply a droplet digital PCR assay for the detection and quantification (copies μL−1) of the beef, pork, horse, sheep, chicken and turkey in meat products. The analysis conducted on commercial meat showed the presence of traces of DNA from other animal species than those declared. We show that the method is highly sensitive, specific and accurate (accuracy = 100%). This method could be adopted by competent food safety authorities to verify compliance with the labelling of meat products and to ensure quality and safety throughout the meat supply chain, from primary production to consumption. 相似文献
93.
Hyuk-Je Woo Ji-Hoon Kang Chae-Hun Lee Kyung Bin Song 《International Journal of Food Science & Technology》2020,55(1):276-282
The present study aimed to examine the antimicrobial activity of silkworm thorn (Cudrania tricuspidata) leaf extract (CTLE) and its application as a washing agent for fresh-cut romaine lettuce and kale. The antimicrobial activities of CTLE at various concentrations against Listeria monocytogenes were determined using disc diffusion and viable cell count assays, and CTLE exhibited strong inactivation of L. monocytogenes. In particular, after the treatment with 0.4% CTLE, the protein content of L. monocytogenes cells was significantly (P < 0.05) decreased from 507.21 to 254.58 μg mL−1, and damaged cells were observed by scanning electron microscopy. CTLE washing resulted in approximately 2-log reduction of microbial growth, similar to that of 0.01% NaOCl. In addition, CTLE washing did not affect the quality of romaine lettuce and kale. Therefore, these results suggest that CTLE is applicable as a new washing agent for inactivating L. monocytogenes on fresh-cut romaine lettuce and kale. 相似文献
94.
Qiang Liu Wenchuan Guo Xinhua Zhu 《International Journal of Food Science & Technology》2018,53(9):2037-2044
Dielectric properties (dielectric constant ε′ and dielectric loss factor ε′′) of whole milk and skim milk with the lactose content of 4.56–6.44% and 4.57–6.47%, respectively, were measured over the frequency range of 20–4500 MHz at 25 °C using a vector network analyzer. The results showed that ε′ decreased with increasing frequency, and ε′′ changed with V shape and its minimum was noted at about 2000 MHz. Whole milk had lower dielectric properties than skim milk at almost same lactose content and a given frequency. ε′ had weak positive linear relationship with lactose content for whole milk, but had negative linear relationship for skim milk. No matter for which milk, ε′′ had very good negative linear relationship with lactose content below 1000 MHz and had good positive linear relationship above 2300 MHz. The study provides information on developing rapid lactose detector for milk in future. 相似文献
95.
96.
针对星座图的射频(RF)指纹识别方案中,低信噪比环境下识别准确率低的问题,提出一种基于欧式距离与幅度距离的二维识别算法来进行RF指纹识别。该方案通过对星座图进行优化处理,可从优化后的星座图中提取识别性能更好的RF指纹,再通过二维识别算法来提高识别准确率。仿真结果表明:与仅用欧式距离作为判断依据的方法相比,所提出的二维识别算法的识别准确率最高可提升8%,在设备容量为50组的情况下识别准确率为77.8%,并且从优化后的星座图中所提取的RF指纹具有更好的唯一性和稳定性。 相似文献
97.
换热单元的生成频次对换热网络优化有直接的影响,分析其机理可以指导求解算法的改进。本文采用节点非结构模型及强制进化随机游走算法,通过设置不同的换热单元生成概率与生成个数以改变换热单元的生成频次,观察并记录个体在优化过程中产生的年综合费用变化情况。发现不同生成频次下整型变量和连续变量的相对优化频率发生了变化,从而改变了整体优化过程,并且与个体当前优化状态不适应的生成频次会造成相对优化频率不平衡、优化结果较差。基于此,本文提出了一种具有生成参数动态调节策略的换热单元生成方式,在优化过程中根据个体状态实时调整换热单元的生成概率与生成个数,平衡整型变量与连续变量的相对优化频率。最后,采用15SP、10SP和20SP算例进行验证,换热网络的年综合费用较文献结果分别下降了1.06%、0.16%、0.68%,验证了该策略使得换热单元的生成频次更为合理,有效地提高了算法的优化效率。 相似文献
98.
AbstractTransverse vibration of a circular cross sectional micro-rod subjected to a new kind of boundary constraints with elastic torsional springs is presented based on nonlocal elasticity. A nonlocal strengthening beam model is utilized and the effect of temperature changing is taken into consideration. The variational method and Hamilton’s principle are applied to derive the governing equation of motion and corresponding boundary conditions. A higher-order partial differential equation that is a typical characteristic of nonlocal strengthening model is developed, and the boundary conditions contain not only classical conditions but also non-classical higher-order conditions. Unlike previous studies which were only concerned with some conventional boundary constraints, we consider more general boundary conditions named elastic torsional spring supports. Such boundary conditions are between the simply supported and clamped ones, and they are closer to the actual constraints of existing engineering structures. Natural frequencies of micro-rods with new boundary constraints are determined via an eigenvalue method and compared with other results in the literature. It is shown that the nonlocal scale factor, thermal parameter, rigidity parameter and torsional spring coefficient play significant roles in free vibration of micro-rods. The research can provide a reference for a large class of boundary conditions ranging from simply supported to clamped micro-rods. 相似文献
99.
长期以来,我国在水利资源管理上存在整体性不足、各自为战的特点,因而在未来发展的过程中,要想提高水利管理的现代化程度,就要重视网络与信息安全结合的整体性,并不断提高研究的层级。基于此,文章主要分析水利信息网络与资源整合共享的必要性,并探讨系统框架分析建设路径,以提高水利网络与信息安全资源共享的实际效果。 相似文献
100.