Detection of acylated homoserine lactones in gram-negative proteolytic psychrotrophic bacteria isolated from cooled raw milk

Through a mechanism called quorum sensing, bacteria are able to express specific genes in response to population density. Cell-to-cell communication in bacteria is mediated by signal molecules such as acylated homoserine lactones (AHLs). This work aimed to detect AHL production in Gram-negative psychrotrophic bacteria isolated from raw milk. A total of 84.9% of the bacteria were identified as AHL producers eliciting a diversity of responses in the AHL-monitor systems. These results demonstrate that AHL-production is common among psychrotrophic bacteria isolated from milk, and indicate that quorum sensing may play an important role in the spoilage of this product.     

TrajStat: GIS-based software that uses various trajectory statistical analysis methods to identify potential sources from long-term air pollution measurement data

Statistical analysis of air mass back trajectories combined with long-term ambient air pollution measurements are useful tools for source identification. Using these methods, the geographic information system (GIS) based software, TrajStat, was developed to view, query, and cluster the trajectories and compute the potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses when measurement data are included.     

基于SSH架构的高职院校成绩管理系统的分析和设计

本文介绍了当前基于Struts2、Spring、Hibernate框架的高职院校成绩管理系统的分析和设计。     

再生塑料内污染物迁移的有限元分析

建立计算仿真模型,该模型可用来预测再生塑料内污染物向液体产品(如食品)的迁移.该仿真模型的建立是基于有限元方法,可分析多层结构中的迁移.该项工作对于再生塑料尤其是有低阻隔性的聚烯烃在食品包装上的应用具有潜在意义.     

An investigation on capacitance-trigger ESD protection devices for high voltage integrated circuits

A novel cascaded complementary dual-directional silicon controlled rectifier (CCDSCR) structure has been proposed and implemented in a 0.5 μm 20 V Bipolar/CMOS/DMOS process as an ESD (electrostatic discharge) protection device. The ESD characteristics of the capacitance-trigger CCDSCR has been investigated by transmission line pulse (TLP) testing. Compared with the substrate-trigger insulated gate bipolar transistor with the enhanced substrate parasitic capacitance, the gate-driven trigger insulated gate bipolar transistor with the gate coupling capacitance and the normal dual-directional silicon controlled rectifier, the CCDSCR has the highest holding voltage of about 25.4 V and the best current conduction uniformity. In addition, it has the best figure of merit (FOM) with the value of about 0.64 mA/μm². The good current conduction uniformity in CCDSCR due to the enhanced substrate parasitic capacitance-trigger effect is finally confirmed by Sentaurus simulations.     

封闭型(6,0)单壁碳纳米管电子传输特性研究

采用广义梯度近似(Generalized gradient approximation,GGA)密度泛函理论与非平衡态格林函数(Non-equilibrium Green’s function,NEGF)相结合的方法对两端封闭型单壁(6,0)碳纳米管进行电子传输的理论研究。在温度为300K的条件下,对不同长度(6,0)单壁碳纳米管(SWNT)进行电子透射概率计算。结果显示,两端封闭型(6,0)碳纳米管的电子传输属于量子化传输模式,并随着碳纳米管长度的增加,某些电子透射概率峰值所对应的能量值并未有大的变化,且呈现线性分布;两端封闭型单壁(6,0)碳纳米管中电子的传输接近无散射弹道传输模式,该系统概率尖峰能量的平均间距约为n×2.2eV,n为整数且1≤n≤6。     

基于改进cordic算法的NCO设计

提出了一种改进cordic(coordinate rotation digital compute,坐标数字旋转)算法,用于实现NCO(数控振荡器)的设计。该算法能够预先确定所有迭代的旋转方向,相对于传统cordic算法,减少了硬件资源消耗。采用Altra公司CycloneII系列芯片EP2C5AF256A7进行FPGA验证,结果符合设计要求。     

Least squares estimation for a class of non-uniformly sampled systems based on the hierarchical identification principle

This paper presents a novel hierarchical least squares algorithm for a class of non-uniformly sampled systems. Based on the hierarchical identification principle, the identification model with a high dimensional parameter vector is decomposed into a group of submodels with lower dimensional parameter vectors. By using the least squares method to identify the submodels and taking a coordinated measure to address the associated items between the submodels, all the system parameters can be estimated. The proposed algorithm can save the computation cost. The performance analysis indicates that parameter estimates converge to their true values. The simulation tests confirm the convergence results.     

低功耗内容寻址存储器的设计

分析了传统内容寻址存储器(CAM)结构,提出其功耗模型。根据功耗模型,设计了一种适用于以太网MAC地址识别的新型低功耗CAM单元结构及其预充电路。基于SMIC 0.18μm/1.8V工艺库,利用HSPICE平台对电路进行仿真,仿真频率为100MHz。结果表明,64×64的新型CAM阵列平均查找时间为0.8955ns,写入功耗和查找功耗分别为22.61μW/b和4.186μW/b,仅为传统CAM结构的12.58%和37.9%。