广东联通WLAN无感知认证应用部署探讨

通过分析目前广东联通WLAN的认证现状和WLAN无感知应用在其他运营商的部署现状,结合当前主流WLAN无感知技术,提出了针对广东联通的WLAN认证平台解决方案,对其他运营商WLAN平台的认证建设和部署具有一定的指导意义。     

数字式可调直流稳压电源设计

随着科学技术的发展,直流稳压电源的应用越来越广泛.针对传统直流稳压电源的稳定性不高的缺点,提出了一种数字式可调直流稳压电源.该电源以单片机为核心控制电路,采用PWM控制,A/D转换等方法调节输出电压,并通过LCD液晶显示器显示输出电压.该系统具有操作简便、稳定性强、调节精度高、输出电压纹波系数小等特点.     

基于FPGA的超声波传感器前端电路设计

超声波传感器广泛应用于风速、风向的测量,前端电路的设计直接关乎系统性能的好坏.为达到稳定的驱动效果,驱动电路采用了低压驱动方式.为能接收稳定、准确的超声波信号,设计了接收及信号处理电路,进行接收抗干扰限幅处理、前置放大、带通滤波、自动增益控制放大和电压比较,将所接收的超声波交变电压信号转换成可供FPGA 直接使用的数字信号.实验结果验证,各个电路模块的设计均满足系统要求.     

Physical, Chemical and Sensory Characteristics of Four Types of Beef Steaks

Four types of beef forequarter steaks, rib eye roll steaks (RER), ser-ratus ventralis solid-muscle structured steaks (SRV), salt/phosphate comminuted structured steaks (NaCl/PO⁴) and algin/calcium comminuted structured steaks (Alg/Ca) were evaluated. Meat purchasers preferred the color, lack of surface discoloration and overall appearance of intact muscle steaks (RER and SRV) over the comminuted structured steaks (NaCl/PO⁴ and Alg/Ca). Purchasers perceived the fat content in SRV steaks to be less than in RER steaks. Sensory evaluations of juiciness and overall desirability were similar for all four types. Intact muscle steaks were lower in sensory tenderness ratings and higher in flavor desirability than comminuted structured steaks. Consumer acceptability was evident for all four types offering merchandising options to beef fabricators.     

Development of a Colorimetric, Second Generation Nucleic Acid Hybridization Method For Detection of Salmonella in Foods and a Comparison With Conventional Culture Procedure

A new, highly specific colorimetric DNA hybridization method (cDNAH) for detection of Salmonella in foods was developed. It detected 355/362 strains representing 206/213 serovars of Salmonella, and showed no cross-reactivity with 32 different non-Salmonella species, including a variety of Enterobacter and Citrobacter species. The cDNAH method was compared with the BAM/AOAC culture method in two studies: (1) with 20 different inoculated and uninoculated foods overall agreement between the two methods was 99%. (2) with naturally contaminated foods at two independent sites agreement with culture was 99.8% where 9/404 samples were positive for Salmonella.     

ORGANIC ACID AND SUGAR CONTENTS OF SCUPPERNONG GRAPES DURING RIPENING

Changes in the principal organic acids and sugars of Scuppernong grapes ( V. rotundifolia ) were followed during the ripening season. The vines were sampled bi-weekly during the initial stages of berry development and then weekly as harvest approached until the "overripe" stage was reached. At the ripe stage, malate and tartrate constituted approximately 90% of organic acids with trace quantities of pyruvic, fumaric, succinic, citric and quinic acids. Glucose, fructose and sucrose constituted approximately 90% of the sugars with trace quantities of galactose and maltose. Malate concentration increased during the early stages of ripening, peaked and decreased to a plateau at the ripe stage. Tartrate decreased steadily until it leveled at the ripe stage. Sugars began to accumulate at veraison, increased rapidly thereafter, and leveled at the ripe stage. At harvest, Scuppernong grapes contained 1.60% total acid and 9.45% total sugars on a whole berry basis. Individual constituents were 0.67% malate, 0.92% tartrate, 3.86% fructose, 3.98% glucose, and 1.61% sucrose.     

MODIFIED-ATMOSPHERE PACKAGING OF BONE-IN PORK LOINS

Paired bone-in pork loins (n = 110 pairs) trimmed to 3.2 and 6.4 mm subcutaneous fat were placed five per box in modified-atmosphere packages (MAP) and stored for up to 19 days at 1°C. Using commercial conditions and a single flush of 0.61 1/kg of meat of carbon dioxide (CO₂), the resulting CO₂ concentration was 78.5%, which then decreased to 55.1% (day 3) and 41% (day 19). Oxygen, 3.1% initially, increased to 7.2% (day 3), decreased to 3% (day 15), then increased to 7.1%. Although microbial counts increased from 3 to 19 days, those through 9 days of MAP (331 CFU/cm²) were lower than prior to MAP (653 CFU/cm²). Longer storage increased (P < 0.05) loin weight loss; off-odor; and discoloration of the blade and sirloin lean, subcutaneous fat, and bone surface. Off-odor intensity and microbial levels were acceptable at day 19, thus discoloration was the limiting factor in loin shelf-life and retail chop display color stability.     

X100试验管线钢管的规范和生产

介绍了位于英国诺林伯利亚,钢管直径1 219 mm(48 in),输气压力18 MPa(180 bar),由英国BP公司承建的X100试验管线的建设概况.根据X100试验管线的设计参数制定了相应的钢管规范,设计了X100管线钢管母材、焊缝金属和热影响区的合金成分.按设计的合金成分由住友金属鹿岛钢铁厂生产了钢材、钢板,并...     

高清MV轻松看,酷我视频体验大升级

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