Predictive models for growth of Salmonella typhimurium DT104 from low and high initial density on ground chicken with a natural microflora

A single strain (ATCC 700408) of Salmonella typhimurium DT104 was used to investigate and model growth from a low (1.12 log10 mpn g(-1)) and high (3.7 log10 cfu g(-1)) initial density on ground chicken with a natural microflora. Kinetic data for growth of the pathogen on ground chicken were fit to a primary model to determine lag time (lambda), maximum specific growth rate (mu) and maximum population density (Nmax). Secondary models for lambda, mu and Nmax, as a function of temperature (10-40 degrees C), were developed and compared among initial densities. Variation of pathogen growth among replicates (n=4 or 5) was higher at 10-18 degrees C than at 22-40 degrees C and was higher for Nmax than lambda and mu. Prediction problems were observed when secondary models developed with one initial density were used to predict lambda, mu and Nmax from the other initial density, especially at 10-18 degrees C and for Nmax. These results indicated that variation of growth among replicate challenge studies and initial density are important factors to consider when developing predictive models for growth of S. typhimurium DT104 on ground chicken with a natural microflora.     

基于VxWorks的油井多参量采集系统设计

阐述了在VxWorks环境下PC104油井多参量采集系统的开发过程,设计开发了采集系统的板载支持包BSP,完成了油井多参量采集模块的驱动,使系统有效地支持A/D转换通道来采集现场各种仪表数据。在VxWorks中,能更容易满足油井多参量采集系统的实时、多任务调度要求,并且在不了解系统硬件结构的情况下,方便地进行后续应用程序的开发,从而缩短系统开发周期。     

Coupled effect of cement hydration and temperature on rheological properties of fresh cemented tailings backfill slurry

The fluidity of fresh cemented tailings backfill (CTB) slurry depends on its rheological properties. Hence, it is crucial to understand the rheology of fresh CTB slurry, which is related to the cement hydration progress and temperature evolution within CTB mixtures. For this reason, a numerical model was developed to predict the evolution of the rheological properties of fresh CTB slurry under the coupled effect of cement hydration and temperature. Experiments were conducted to investigate the rheological behaviours of the fresh CTB slurry. By comparing the simulated results with the experimental ones, the availability of this developed model was validated. Thereafter, the model was used to demonstrate the coupled effect of cement hydration and temperature on the evolution of fresh CTB slurry's rheological properties, under various conditions (initial CTB temperature, cement to tailings ratio, and water to cement ratio). The obtained results are helpful to better understanding the rheology of CTB slurry.     

Preparation and analysis of high capacity polysulfone capsules

Since the concept of solvent impregnated resins was introduced in the early 1980s, the technique has been applied to a limited amount of applications. The main disadvantage of the resins was that the amount of solvent inside was limited to approximately 1.5 ml/g polymer. A new generation of solvent impregnated resins is introduced. These capsules can contain up to 11.8 ml solvent/g polymer and were prepared using a modified dry impregnation technique. Due to the high solvent loading, the capacity per volume of capsule for extracting products from aqueous phases is therefore dramatically increased.     

Half-Lives and Gamma-Ray Energies of Short-Lived Molybdenum Isotopes

Short-lived molybdenum isotopes produced by the ²³⁶U(n, f) reaction were isolated by rapid paper electrophoretic technique. Gamma-ray spectra of the isolated molybdenum fraction were measured with high resolution Ge(Li) detector. The half-lives of ¹⁰³Mo (70±1 sec), ¹⁰⁴Mo (66±2 sec) and ¹⁰⁵Mo (30±3 and 40±5 sec) were determined by analyzing the genetic relationships of the known photopeaks of their technetium daughters. Decay analysis of observed photopeaks free from interference resulted in the detection of many new short-lived photopeaks with half-lives of 10–70 sec, and which were not relevant to technetium isotopes. These new photopeaks were ascribed to ^103-106Mo, based on examination of their decay behavior.     

基于PC104的电能数据综合采集系统

介绍了一种基于 PC1 0 4的电能数据综合采集系统 ,对 PC1 0 4的应用特点进行了描述 ,阐述了系统软、硬件的设计思想和具体实现。该系统的特点是采集数据路数多、功能配置灵活、可扩充性强     

PC/104标准嵌入式扩展通信板设计

PC／104标准计算机正被越来越多地使用于各种嵌入式控制系统中，而其串行口往往既要用来连接必要的外围设备又要通过它实现各部分之间的通信。PC／104所提供的两个标准RS—232串行口一般不能满足控制系统的需求，因此需要开发扩展通信板。本文介绍了利用TLl6C554和PLD电路设计四串口通信板的方法，电路板结构紧凑，兼容性好，能实现RS—232和RS—485通信，RS—485通信还具有自动识别信号极性的功能。     

基于PC/104总线的嵌入式气动机械手控制器研究

对有非线性的气动机械手进行位置伺服控制,采用PC/104嵌入式计算机模块搭建控制器硬件电路,从而取代工控PC机实现了控制器的小型化、低功耗、低成本需求。采用Windows CE.NET 4.2作为操作系统,借助Embedded Visual C 4.0编写控制系统软件,并以模糊PID算法作为控制器的控制算法,最终实现气动机械手实时跟踪人手在触摸屏上的书写输入功能。     

Comparison of corrosion behavior of Zl104 alloy at as —cast and heat treatment states

The corrosion behavior of ZL104 alloy at different states(as-cast and heat treatment) in salt spray corrosion (SSC) was studied.The results show that the sample treated after refinement and modifciation has the least corrosive resistance compared with the sample bearing as -cast stucure at the beginning of the corrosion.As the corrosion process continued.however,the trend reversed itself.After 44h continuous corrosion,the corrosive rates of all samples tend to be stable.After experiments,the sample bearing as -cast structure had the most corrosive products on the surface whereas the sample being refined and modified had the least products.The Fourier transformation infrared spectroscopy(FTIR) analyses of the corrosion products show that these products are composed of hydroxyl-containing substances.     

PC104总线与DSP数据通信接口设计

用DSP芯片进行实时高速的数字信号处理已经在军事、工程中有着十分广泛地应用。在工程应用中，工业控制计算机采集数据，然后通过PC104总线向DSP芯片传递实时数据，由DSP芯片完成算法的处理。PC104总线与DSP芯片之间的数据通信控制用CPLD来实现。本文是CPLD在工程中的一种应用。