基于PML结构文件的MapReduce算法优化*

针对目前物联网和云计算技术结合后,物联网RFID产生的小型数据致使云计算中MapReduce算法产生运算瓶颈问题进行了研究。运用PML和EPC编码技术保证了数据存储的完整,采用快速排序和改进XGrind压缩技术对于MapReduce算法进行优化。由实验获得,优化后MapReduce算法减小64%的I/O吞吐和45%的CPU耗用,同时使查询数据效率提高75%,可改善查询物联网获取的海量信息的效能。最终通过对云计算下MapReduce算法的优化,为云计算下的物联网追溯平台数据高效使用提供了技术支撑。     

评价动态有效位数的述评

介绍了动态有效位数的含义及溯源性,以及评价动态有效位数的两种方法－－正统波拟合法和FFT法,并说明了其各自的优缺点,此外,详细讨论了评价动态有效位置过程中应注意的几个问题：等相位密度采信问题、整周期信号采样问题、拟合收敛性问题、拟合初始值选取问题和校准软件评价问题等。同时给出了两条具有典型代表性的动态有效位数频率特性曲线的实测例证。     

基于全基因组序列的污染事件中椰毒假单胞菌酵米面亚种溯源分析

摘 要：目的 对湿米粉与淀粉制品（统称为“湿粉”）及其原料米中分离的椰毒假单胞菌酵米面亚种进行溯源分析。方法 采用GB/T 4789.29—2003在14份湿粉及其原料米中分离出34株唐菖蒲伯克霍尔德氏 菌并进行菌株全基因组重测序,以Burkholderia_gladioli_Co14作为参比基因,基于单核苷酸多态性（SNP）数据构建进化树,分析不同菌株的同源关系。结果 来源于相同产地标识的样品的菌株呈现较好聚类;来源于同一生产企业的湿粉和碎米样品的菌株具有高度同源关系。结论 提示原料米中椰毒假单胞菌酵米面亚种的基因组序列与产地溯源具有较大的相关性,在湿粉生产加工过程中存在椰毒假单胞菌酵米面亚种污染传递的风险。     

PCR detection of Lactobacillus sanfranciscensis in sourdough and Panettone baked product

Sourdoughs, in which Lactobacillus sanfranciscensis is the predominant bacterial species, are distinctive of some traditional Italian sweet baked products like Panettone. The direct extraction of amplifiable bacterial DNA from products subjected to heat treatment represents a valid tool to identify and trace microbial species originally present in the food matrices. Three types of protocols for the isolation and clean-up of DNA (CTAB, Wizard^® DNA Clean-Up System, NucleoSpin^® Food) were applied on mother, final dough and end-product samples and compared through the determination of the maximum amplifiable dilution by a PCR reaction targeting two fragments (1460 and 153 bp long) of 16S rDNA region of Lb. sanfranciscensis. CTAB extracting protocol was revealed to be the best for isolating DNA. In dough samples the amplification with the 153 bp fragment showed signals at concentration levels that are comparable with the values obtained from the plate counts, and two log cycles higher than those found with the amplification targeting the 1460 bp fragment. In the cooked samples only the 153 bp amplicon was detected, indicating that oven cooking degrades DNA into small fragments.     

Indications for the applicability of element signature analysis for the determination of the geographic origin of dried beef and poultry meat

In order to determine the geographic origin of poultry and dried beef, concentrations of a total of 72 different elements (occasionally represented with several isotopes) were analyzed by inductively coupled plasma high resolution mass spectrometry (ICP-HRMS). Additionally, gross chemical composition (GCC) was analyzed. The 25 poultry breast filets samples originated from Switzerland, France, Germany, Hungary, Brazil, and Thailand, and the 23 dried beef samples, made from M. biceps femoris and M. semitendinosus, were produced in Switzerland, Austria, Australia, United States, and Canada out of raw meat originating either from these or from other countries. A total of 66 and 46 of the elements and isotopes followed were detected in beef and poultry, respectively. For statistical analyses, only the most abundant isotopes per element were used. For both poultry meat and dried beef, a differentiation of the origins was possible using those elements, which were significantly different across countries (As, Na, Rb, and Tl in poultry; B, Ca, Cd, Cu, Dy, Eu, Ga, Li, Ni, Pd, Rb, Sr, Te, Tl, Tm, V, Yb, and Zn in beef). No sufficient differentiation between origins was possible with GCC. Further studies have to confirm the suitability of this approach for meat authentication with more samples.     

Detection of bovine DNA in raw and heat-processed foodstuffs, commercial foods and specific risk materials by a novel specific polymerase chain reaction method

The identification of beef in animal foods is a major concern not only for the prevention of commercial fraud, but also to avoid safety risks deriving from the presence of prohibited bovine material that might be harmful to both human and animal health. Here we report a novel set of bovine-specific primers, CYTbos1 (forward) and CYTbos2 (reverse), which allow the specific amplification of a 115 base pair fragment of the bovine cytochrome b gene (cytb) between nt 844 (mitochondrial site 15,590) and nt 958 (mitochondrial site 15,704), no cross-reaction being observed with DNA from another 12 frequent commercial meat species. The polymerase chain reaction product obtained is cleaved specifically by endonucleases ScaI and TspE1 to achieve further confirmation evidence. The sensitivity of the proposed method was 0.025%. The CYTbos primers successfully detected bovine DNA in meat samples processed for 20 min at 133 °C/300 kPa or for 2 h at 121 °C. CYTbos primers also detected bovine DNA in heat-processed commercial meat products exhibiting a complex nature, as well as in bovine specific risk materials. The proposed polymerase chain reaction method, aimed at detecting a small and specific fragment of the bovine mitochondrial DNA, may be especially useful for the direct identification of bovine DNA in foodstuffs subjected to severe heating under overpressure conditions.     

水产品可追溯信息管理系统的设计

以SQLServer2005和ASP．NET为开发平台,采用RFIO技术和zigbee技术,建立起一个多层次、多用户、多权限的水产品追溯系统。该系统主要由读写器和一个面向对象的信息管理平台组成,其中读写器通过RFID技术读写标签,并采用zigbee技术与上位机的通信,实现数据的读取、查询功能。该系统以水产品供应链中重要采集点的信息为信息源,实现信息的采集、传输、管理、存储、查询等功能。     

基于无线射频识别技术的商品猪精准养殖与管理系统设计

当前我国商品猪养殖业快速发展,但养殖设施和技术手段还比较落后。本文设计商品猪的精准养殖与管理系统,利用无线射频识别技术实现猪身份的准确快速识别,利用电子称和以太网传输技术实现猪体重和摄食量的实时采集与传输,利用可编程控制技术实现环境参数的监控,并对养殖场日常信息进行数字化管理。通过试验表明,猪身份能够准确识别,摄食量和体重能够及时准确获取,环境因子参数控制范围达到了设计要求,能够满足商品猪精准养殖与管理的需要,同时可提供商品猪养殖全过程的相关信息,供溯源查询与分析。所设计的系统为研究不同品种猪或者同一品种不同阶段的猪的采食规律、最佳饲喂效果和建立营养模型提供了第一手的资料,为猪的可溯源管理打下基础,该系统亦可以推广到其他畜禽的精准养殖过程中。     

基于RFID技术的生鲜肉类产品全程可追溯系统设计

为了加强生鲜肉类产品全程跟踪和监控水平,实现生鲜肉类产品安全生产和流通,本文设计了基于RFID技术的生鲜肉类产品全程可追溯系统,并对其工作原理、系统拓扑结构、功能模块以及系统实现的关键技术进行了研究,实现了生鲜肉类产品从生产养殖、屠宰加工、仓储配送到销售终端全程信息的采集与监控,提升了生鲜肉类产品质量安全监管水平。     

Accurate velocity measurements of AFM-cantilever vibrations by Doppler interferometry

Doppler velocimetry is widely used in the measurement of nanometre resonance vibrations of micro-electromechanical systems (MEMS). It has excellent sensitivity and precision, but typical engineering applications do not require traceability of these velocity measurements to the SI system. While Doppler velocimetry is, in principle, easy to make traceable to the velocity of light, in practice a frequency-to-voltage conversion in common commercial instruments breaks this traceability unless calibrated. Typically, though, calibration is performed at a much lower frequency than those typical of MEMS devices, without the guarantee that the calibration is applicable in this higher frequency regime.

We present a method of traceable measurement of velocity in terms of the velocity of light, valid for the range of frequency and nanometre amplitudes typical of MEMS devices driven to resonance vibration. This is achieved by analysis of sideband amplitudes in the interference spectrum before demodulation of the Doppler signal. These sideband amplitudes can conveniently be measured using a benchtop spectrum analyser, a piece of widely available electrical test equipment. We illustrate the method with measurements on individual AFM cantilevers. In combination with cantilever calibration methods based on MEMS devices this method enables traceable calibration of those cantilevers employed for the measurement of pico- and nanonewton forces between individual biomolecules.