Pile Foundation Analysis Using a Boundary Element Method

Taking the extended Mindlin solution of a vertical point load acting in the interior of a multi layered elastic medium as the basic solution, an indirect boundary element method (BEM) was adopted to analyze pile foundations embedded in a multi layered elastic soil. The numerical analysis was carried out by the compiled program for a pile foundation in an homogeneous soil and a pile foundation in a multi layered soil. Reasonably good agreement is obtained between the present and existing solutions. Compared with the FEM software ABAQUS, the computational speed of BEM is much faster than that of FEM. Applying BEM in practice is convenient. It is pointed out that the exact measurement of elastic modulus is the key factor for applying BEM in geotechnical engineering.     

A controller area network based electric vehicle drive system design

To solve the key problems of the electric drive system, a controller area network(CAN) based electric drive system for electric vehicles was designed. The system was composed of two parts: a CAN communication module and a motor control module. The newest transceiver (TJA1040) and a stand alone CAN controller were used during the design of the CAN communication module, and anti jamming measures were employed to guarantee communication stability. The fuzzy vector control method and direct speed control were applied to realize highly robust control functions. This system has high compatibility. It can be installed in electric vehicles as an independent module and be extended through CAN Bus.      

An algorithm of symbol timing rapid acquisition and tracking for π/4 DQPSK signals

Methods of IF difference detection combined with rapid acquisition synchronization and tracking principle by parallel processing methods were proposed in order to quickly achieve synchronous digital capture and tracking in π/4 DQPSK demodulation.Field program grid array (FPGA) technology to achieve rapid detection of synchronous capture and symbol tracking was adopted by using the improved algorithm in parallel with signal acquisition and frequency offset acquisition. This adoption took into account the characteristics of π/4 DQPSK and was in accordance with the detection of rapid acquisition synchronization and the tracking principle. The experimental results show that clock synchronization signals can be restored stably in eight symbol bit, accurately realize bit timing, and possess strong anti interference capability without affecting frequency differences. This proposed algorithm is suited for frequency hopping communication systems with high transmission rates.     

Tests and analysis on energy consumption of heating ventilating and air conditioning systems in commercial buildings

Three typical commercial buildings in Chongqing, P.R. China were selected to study the actual summertime operation and energy situations of heating ventilating and air conditioning (HVAC) systems in commercial buildings. Based on tests of energy consumption of HVAC systems in these three buildings, we analyzed the electricity consumption of the main components of the air conditioning systems. The energy efficiency of the chillers and air conditioning water distribution systems were studied. The indoor thermal environment in these three buildings were also tested and discussed. It is concluded that problems exist in the air conditioning systems of commercial buildings. Among the problems are over sized system design, low equipment operating efficiencies, poor operation management, and lack of indoor temperature controls. To reduce energy consumption of HVAC systems in commercial buildings, we propose energy efficient strategies such as sizing systems based on accurate load calculation and automatic control under partial load conditions.     

葡萄酒香气成分萃取中固相微萃取纤维的选择

【目的】针对葡萄酒香气成分气相色谱分析的要求,比较了3种固相微萃取纤维萃取葡萄酒香气成分的效果。【方法】选用常用的PA、PDMS/DVB、PDMS 3种固相微萃取纤维进行葡萄酒香气成分的富集、浓缩处理,然后用GC-MS检测香气成分。通过对不同固相微萃取纤维萃取香气成分的数量、化学种类以及各类化合物累积峰面积标准化值的比较,评价供试固相微萃取纤维萃取葡萄酒香气成分的效果。【结果】3种固相微萃取纤维萃取出的葡萄酒香气成分中,高级醇、化学酯和有机酸是主要成分,萜烯醇、β-大马酮、挥发性酚和呋喃酮等是微量成分。不同固相微萃取纤维萃取的化合物存在明显差异,PA萃取出化合物49种,PDMS萃取出53种,PDMS/DVB仅萃取出38种。累积峰面积标准化值分析表明,PA萃取高级醇、有机酸、3-甲硫基-1-丙醇、2(3H)-二氢呋喃酮、2,4-二季丁基苯酚的灵敏度高;PDMS萃取化学酯类、萜烯醇和β-大马酮的灵敏度高;PDMS/DVB几乎萃取各类化合物的灵敏度都低。【结论】在供试的3种固相微萃取纤维中,PDMS是萃取富集绝大多数葡萄酒挥发性成分的最佳纤维。     

网络医学学术信息资源的分类及其评析

通过对网络医学学术信息资源的分类及其评价分析,提出建立 网络医学学术信息资源检索导航系统的初步设想,帮助用户提高对网络医学学术信息资源 的甄别与应用能力。     

基于Web of Science数据的生物信息学同被引聚类分析

以Web of Science网络数据库中2007年的生物信息学文献为源文献,对高频被引论文进行同被引聚类分析,同时应用多维标度技术获得同被引论文的二维散点图,〖XD〗结合生物信息学和情报学知识总结该领域的学科结构和研究热点。

     

河南周口夏玉米大豆同穴混作高产栽培研究

本研究探讨解决周口市玉米单作产量低,效益少,大豆种植面积较少的问题,夏玉米大豆同穴混作是解决这一问题的有效途径。     

QuEChERS-超高效液相色谱-串联质谱法同时测定大米、小麦和动物源食品中异丙隆及其代谢物脱甲基异丙隆残留

本研究建立了超高效液相色谱-串联质谱法(UHPLC-MS/MS)同时测定异丙隆及其代谢物脱甲基异丙隆在大米、小麦、牛肉、牛奶、鸡肉和鸡蛋的残留检测方法。样品经2%甲酸乙腈提取,以N-丙基乙二胺(PSA)净化,利用乙腈和0.2%甲酸水作为流动相梯度洗脱,T3色谱柱分离,在多反应监测模式下定量分析,基质外标法定量。结果表明:异丙隆及其代谢物脱甲基异丙隆溶剂标准曲线和基质标准曲线在1~1 000μg/L范围内线性关系良好,相关系数均大于0.99。在4个加标水平下,异丙隆日内平均回收率为74.0%~107.0%,相对标准偏差0.7%~12.9%;日间平均回收率为76.2%~108.7%,相对标准偏差1.1%~19.8%。脱甲基异丙隆日内平均回收率为76.9%~113.5%,相对标准偏差0.6%~13.9%;日间平均回收率为77.7%~107.4%,相对标准偏差2.2%~17.4%。异丙隆和脱甲基异丙隆的定量限均为1.0μg/kg。该方法简便、快捷、准确、灵敏度高,适用于异丙隆和脱甲基异丙隆在大米、小麦、牛肉、牛奶、鸡肉和鸡蛋6种基质中残留的检测,为解决异丙隆和脱甲基异丙隆在食品中残留的安全问题提供技术方法。     

香蕉棒孢霉叶斑病菌防治药剂室内毒力测定

由多主棒孢菌Corynespora cassiicola引起的香蕉叶斑病是香蕉产区的主要叶斑病之一。为筛选对该病菌具有抑制作用的杀菌剂,采用菌丝生长速率法,选用7种杀菌剂对其进行了室内毒力测定。结果表明,丙环唑效果较好,EC_(50)4.247 mg/L,其次为多抗霉素和苯甲·丙环唑,EC_(50)分别为4.722和5.999mg/L,这3种杀菌剂对多主棒孢菌具有显著抑制作用。