施工现场漏电保护装置的合理安装及使用

本文从漏电保护装置的工作原理、作用、正确选用、安装和运行、现场使用中应注意的一些问题等方面,结合在施工现场的实践应用,探讨了施工现场漏电保护装置的合理安装及使用问题,供大家交流参考。     

聚合物材料抗静电剂及其应用

简要介绍了聚合物材料抗静电剂的主要性能和使用方法,探讨了抗静电剂的作用机理,并着重介绍了几种典型的应用实例。     

Detection of insect fragments in wheat flour by near-infrared spectroscopy

Insect fragments in commercial wheat flour are a major concern to the milling industry because consumers expect high quality and wholesome products at the retail level. Thus, the US Food and Drug Administration (FDA) has established a defect action level of 75 insect fragments per 50 g of flour. Millers routinely test their wheat flour to comply with this federal requirement and to deliver sound flour to their consumers. The current standard flotation method for detecting fragments in flour is expensive and labor intensive. Therefore, we examined the possible use of a rapid, near-infrared spectroscopy (NIRS) method for detecting insect fragments in wheat flour. We also compared the sensitivity and accuracy of the NIRS method with that of the current standard flotation method. Fragment counts with both techniques were significantly correlated with the actual number of fragments present in flour samples. However, the flotation method was more sensitive than the NIRS method with fragment counts below the FDA defect action level. We were unable to predict whether the number of fragments in a sample exceeded the FDA action level with our NIRS instrumentation. However, we were able to predict accurately whether flour samples contained less than or more than 130 fragments. Although current NIRS instruments are unable to detect insect fragments at the FDA action level, this method should be re-examined in the future because NIRS technology is rapidly improving.     

In vitro antimicrobial effects and mechanism of action of selected plant essential oil combinations against four food-related microorganisms

The aim of this study was to evaluate the antimicrobial efficacy of selected plant essential oil (EO) combinations against four food-related microorganisms. Ten EOs were initially screened against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Saccharomyces cerevisiae using agar disk diffusion and broth dilution methods. The highest efficacy against all the tested strains was shown when testing the oregano EO. EOs of basil and bergamot were active against the Gram-positive bacteria (S. aureus and B. subtilis), while perilla EO strongly inhibited the growth of yeast (S. cerevisiae). The chemical components of selected EOs were also analyzed by GC/MS. Phenols and terpenes were the major antimicrobial compounds in oregano and basil EOs. The dominant active components of bergamot EO were alcohols, esters and terpenes. For perilla EO, the major active constituents were mainly ketones. The checkerboard method was then used to investigate the antimicrobial efficacy of EO combinations by means of the fractional inhibitory concentration index (FICI). Based on an overall consideration of antimicrobial activity, organoleptic impact and cost, four EO combinations were selected and their MIC values were listed as follows: oregano–basil (0.313–0.313 μl/ml) for E. coli, basil–bergamot (0.313–0.156 μl/ml) for S. aureus, oregano–bergamot (0.313–0.313 μl/ml) for B. subtilis and oregano–perilla (0.313–0.156 μl/ml) for S. cerevisiae. Furthermore, the mechanisms of the antimicrobial action of EO combinations to the tested organisms were studied by the electronic microscopy observations of the cells and the measurement of the release of cell constituents. The electron micrographs of damaged cells and the significant increase of the cell constituents' release demonstrated that all EO combinations affected the cell membrane integrity.     

行动规划视角下的总体城市设计方法——以安吉县城总体城市设计为例

我国现阶段总体城市设计在实现城市特色目标方面的实施效果并不理想,主要由于总体城市设计设定的目标需求与实施方法供给之间存在差距,表现在缺乏核心要素提炼,编制成果内容过于泛化,对行动计划重视不足等。安吉县城总体城市设计开展了基于行动规划理念的设计方法研究,通过拓展设计内容,进行一体化设计,围绕核心要素突出阶段目标及工作重点的设计体系,强化了行动规划,有效增强了总体城市设计的实施性。     

Board-level built-in self-repair method of RAM

This paper describes the method of built-in self-repairing of RAM on board, designs hardware circuit, and logic for the RAM’s faults self-repairing system based on FPGA. The key technology is that it utilizes FPGA to test RAM according to some algorithm to find out failure memory units and replace the faulty units with FPGA. Then it can build a memory that has no fault concern to external controller, and realizes the logic binding between external controller and RAM. Micro Controller Unit (MCU) can operate external RAM correctly even if RAM has some fault address units. Conventional MCS-51 is used to simulate the operation of MCU operating external memory. Simulation shows FPGA can complete the faulty address units’ mapping and MCU can normally read and write external RAM. This design realizes the RAM’s built-in self-repairing on board.     

Human action recognition using Pose-based discriminant embedding

Manifold learning is an efficient approach for recognizing human actions. Most of the previous embedding methods are learned based on the distances between frames as data points. Thus they may be efficient in the frame recognition framework, but they will not guarantee to give optimum results when sequences are to be classified as in the case of action recognition in which temporal constraints convey important information. In the sequence recognition framework, sequences are compared based on the distances defined between sets of points. Among them Spatio-temporal Correlation Distance (SCD) is an efficient measure for comparing ordered sequences. In this paper we propose a novel embedding which is optimum in the sequence recognition framework based on SCD as the distance measure. Specifically, the proposed embedding minimizes the sum of the distances between intra-class sequences while seeking to maximize the sum of distances between inter-class points. Action sequences are represented by key poses chosen equidistantly from one action period. The action period is computed by a modified correlation-based method. Action recognition is achieved by comparing the projected sequences in the low-dimensional subspace using SCD or Hausdorff distance in a nearest neighbor framework. Several experiments are carried out on three popular datasets. The method is shown not only to classify the actions efficiently obtaining results comparable to the state of the art on all datasets, but also to be robust to additive noise and tolerant to occlusion, deformation and change in view point. Moreover, the method outperforms other classical dimension reduction techniques and performs faster by choosing less number of postures.     

新型微生物源天然食品防腐剂及其抑菌性能

天然食品防腐剂按其来源的不同可分为植物源天然防腐剂、动物源天然防腐剂以及微生物源天然防腐剂等类型.天然微生物源食品防腐剂由于其本身的优越性,越来越受到人们的青睐.本文主要对五种新型微生物源天然食品防腐剂(即乳球菌肤、溶菌酶、聚赖氨酸、苯乳酸及曲酸)的理化特性、抑茵机制和抑茵特性等进行了概括和论述.旨在为我国新型、安全、高效、微生物源天然食品防腐剂的研究和开发提供参考.     

脲酶/硝化抑制剂在土壤N转化过程中的作用

综述了脲酶抑制剂/硝化抑制剂对土壤氮的转化过程:尿素水解过程、硝化过程、硝酸盐淋溶过程、反硝化过程、微生物固持过程、N矿化过程及气体挥发过程的影响和抑制剂的作用机理,并提出今后研究的发展方向,为今后如何施用抑制剂来提高土壤中氮素利用率和减少环境污染提供一定的参考价值。     

Online discrete-time LQR controller design with integral action for bulk Bucket Wheel Reclaimer operational processes via Action-Dependent Heuristic Dynamic Programming

In this paper, a novel approach for online design of optimal control systems applied to the bulk resumption process by bucket wheel reclaimer (BWR) is presented. This approach is based on reinforcement learning paradigms, more specifically Action Dependent Heuristic Dynamic Programming (ADHDP), that learn online in real-time the Discrete Linear Quadratic Regulator (DLQR) optimal control solution with integral action. Due to the geometric irregularities of the storage yard stacks and variation in physical and chemical characteristics of the stacked material, the flow control of solid bulks by bucket wheel reclaimer requires methods that are suitable with the high degree of imprecision of process variables and environment uncertainties. The resumption of bulk solids is carried out by dividing the stack into layers, each layer is approximately 4 m high, and the layers are divided into workbenches up to 12 m in length. To take up a workbench several translation steps are required (penetration in the stack), with the translation step varying from 0 to 1 m. In order to maintain the desired ore flow throughout the process, the BWR lance speed must be periodically adjusted. The main advantage of the proposed control method is that besides the decision rule is fully independent of plant model, the gains of the resulting controller are self-adjustable. The control system was designed in such a way that the ADHDP-based DLQR controller with integral action would act in real-time in the plant control, using only the input and output signals and states measured along the system trajectory.