Multiple lines of evidence to identify the sources of fecal pollution at a freshwater beach in Hamilton Harbour, Lake Ontario

Multiple microbial source-tracking methods were investigated to determine the source of elevated Escherichia coli levels at Bayfront Park Beach in Hamilton Harbour, Lake Ontario. E. coli concentrations were highest in wet foreshore sand (114,000 CFU/g dry sand) and ankle-depth water (177,000 CFU/100mL), declining rapidly in deeper waters. Many gull and geese droppings were enumerated each week on the foreshore sand within 2m of the waterline. Both antimicrobial resistance analysis and rep-PCR DNA fingerprinting of E. coli collected at the beach and nearby fecal pollution sources indicated that E. coli in sand and water samples were predominantly from bird droppings rather than from pet droppings or municipal wastewater. Both methods indicated a trend of decreasing bird contamination, and increasing wastewater contamination, moving offshore from the beach. When foreshore sand was treated as a reservoir and secondary source of E. coli, waterborne E. coli were found to be more similar to sand isolates than bird or wastewater isolates out to 150 m offshore. Multiple lines of evidence indicated the importance of bird droppings and foreshore sand as primary and secondary sources of E. coli contamination in beach water at Bayfront Park.     

低品位热能利用与减缓气候变暖

低品位热能利用受冷源的制约,其可利用能的温度范围较窄,大部分热能作为废热被排放。本文通过新的制冷循环的建立,探索提高低品位热能制冷效率的方法。新的制冷循环以空气或空气中的主要成分为循环工质,由相互连接、相互影响的气动压缩循环子系统、冷量增益循环子系统和低压补冷循环子系统三部分组成。新的制冷循环以低品位热能作为主要能源,电能作为辅助能源,以期达到更高的能效比,从而使制造冷源成为可能。提高低品位热能的利用率,对减缓气候变暖发挥重要作用。     

Speech separation using speaker-adapted eigenvoice speech models

We present a system for model-based source separation for use on single channel speech mixtures where the precise source characteristics are not known a priori. The sources are modeled using hidden Markov models (HMM) and separated using factorial HMM methods. Without prior speaker models for the sources in the mixture it is difficult to exactly resolve the individual sources because there is no way to determine which state corresponds to which source at any point in time. This is solved to a small extent by the temporal constraints provided by the Markov models, but permutations between sources remains a significant problem. We overcome this by adapting the models to match the sources in the mixture. We do this by representing the space of speaker variation with a parametric signal model-based on the eigenvoice technique for rapid speaker adaptation. We present an algorithm to infer the characteristics of the sources present in a mixture, allowing for significantly improved separation performance over that obtained using unadapted source models. The algorithm is evaluated on the task defined in the 2006 Speech Separation Challenge [Cooke, M.P., Lee, T.-W., 2008. The 2006 Speech Separation Challenge. Computer Speech and Language] and compared with separation using source-dependent models. Although performance is not as good as with speaker-dependent models, we show that the system based on model adaptation is able to generalize better to held out speakers.     

Design and implementation of a VSC for interconnection with power grids,using the method of identification the system through state space for the calculation of controllers

The paper presents the analysis, design and results of a Voltage Source Converter (VSC) when applying PID Controller. Results were obtained through digital simulation and through physical implementation. VSC allows to control independently the active power and reactive power flow injected to the grid. PID controller was implemented considering the system model. The model is obtained through of the identification using state space.     

造船系统直流手工电弧焊电源选型论证

本文通过船厂焊接工况条件的评价体系,进行船用焊机选型论证、焊接电源外特性、技术经济指标对比后,认为ZXE1-400、500交直流两用弧焊机系船厂用焊接设备的优选品种。     

基于CPLD控制的DDS数字频率合成器设计

介绍了ADI公司新一代DDS芯片AD9952和XILINX公司新一代CPLD产品XC2C128的主要性能，提出了用XC2C128作控制电路，由AD9952构成宽带、低相噪、低功耗数字合成频率源的设计方案，同时对如何提高DDS频谱纯度进行了探讨，给出了超宽带应用电路解决方案。     

钴源退役过程的辐射防护与剂量监测

辐照技术的应用日益广泛，辐射源的退役也越来越受到关注。苏南某单位辐照室建立于20世纪80年代初，2001年4月对最早投入运营的39根钴源进行退役，退役过程分三个阶段，历时48小时。由于经过了精心的准备，采取了有效的防护措施，退径过程没有出现工作人员受超剂量照射的情况。     

高清晰度电视芯片中视频和音频同步的异步实现

高清晰度电视的传输流采用了MPEG－2系统层标准ISO／IEC 13818－1。阐述了高清晰度电视（HDTV）传送流中时间信息码在视频和音频同步中的作用，分析了信源解码器中视频和音频同步的原理。就实际芯片中系统时钟的恢复，视频和音频的跳帧等机制进行了讨论，并提出了一种非锁相异步全数字视音同步实现方案。该方案采用了直接置数法恢复系统时钟,滞后跳帧法实现视频与系统时钟的同步，数字锁相法控制音频与系统时钟同步，最后，对视频帧率和音频PCM时钟的偏差等问题作了进一步的探讨。     

Heat sources — technology, economy and environment

Heat sources for heat pumps in buildings as well as in industry are discussed. Furthermore, some environmental aspects concerning choice of heat source are highlighted. Only systems for heat pumping are included, i.e. air-conditioning types which can also partly work as heat pumps are excluded. Recent heat pump installations in Sweden are mainly in small systems. Ambient air, exhaust air, soil and rock are the most common heat source types. Data on COP, investment costs, working fluids, present Swedish market etc. for these types of heat sources are given. Data on industrial heat pump installations in some countries and distribution of these according to heat pump type and industry sector as well as heat source temperatures are reported. Process integration aspects when choosing heat source size and temperature are also discussed as well as the relation between these parameters and the choice of heat pump type. Finally, the influence on the economy of the heat source temperature is presented. The cost-effectiveness of heat pumps for reducing CO₂ emissions compared with other heating technologies is discussed. The main results are: (1) heat pumps can in many cases in the future contribute to a reduction of CO₂; (2) there is a rather big difference, for larger systems a major difference, between the water-based and the ambient air-based heat pumps in terms of efficient reduction of greenhouse gas emissions.     

弹性波理论研究──关于球面波首项(Ⅰ)

本文推导了球面波在弹性介质中传播的首项公式，包括直达波，反射波和透射波的首项。通过对球面波分解。用柱面波合成球面波；在界面上由压力和速度连续条件，给出了人射波，反射波和透射波的表达式；对汉格尔函数用大自变量展开，用最陡下降法分别求出这三种波的首项解析表达式。