钻孔咬合桩在施工中的应用分析

钻孔咬合桩是一种新型的基坑围护形式,采用全套管钻机施工,素砼桩和钢筋砼桩相互咬合形成具有防渗作用的连续挡土结构。本文主要介绍钻孔咬合桩在国内软土地区施工过程中遇到的问题和处理方法。     

砼芯搅拌桩单桩沉降的简化计算

通过总结砼芯搅拌桩的研究成果,将砼芯搅拌桩的沉降视为桩周土体剪切变形和桩身压缩沉降的叠加。分别采用剪切位移法和孤立单桩的弹性力学方法进行计算。通过实例验证,在设计荷载作用下,计算值与实测值能较好吻合,具有较好的实用价值。     

原料验收中运用HACCP原理控制隐形食品添加剂

于原料验收被上游企业“陷害”造成的食品添加剂违规屡见不鲜, 这些“隐形”食品添加剂必须有效控制才能确保食品安全。HACCP体系中原料验收常作为关键控制点, 但很少有企业管控原料的原料。建议食品生产企业通过索取资料、勘察包装和针对性检测进行定性识别, 通过折算理论含量、实际检测分析进行定量识别; 按照严重性和发生概率的大小明确重点管控品种, 对接近关键限值的加大管控力度。具体可逐批核对包装、及时索取资料, 按周期实施检测; 建议采购市售原料批批检测, 推进从农田到餐桌的全过程管理体系。通过运用HACCP原理能有效发现“隐形”添加剂、有利于判定责任, 能推进政府和企业合作, 有利于保障消费者知情选择权和监督权。     

动态连续潮流与自适应混沌粒子群结合计算静态电压稳定裕度

提出一种动态连续潮流(Dynamic Continuation Power Flow,DCPF)与自适应混沌粒子群优化算法(Adaptive Chaotic Particle Swarm Optimization,ACPSO)结合求取系统最大静态电压稳定裕度的方法。该方法以静态电压稳定裕度最大为目标函数,针对连续潮流在处理不平衡功率上存在不足,将动态潮流算法引入到连续潮流模型中,根据发电机和负荷的静态频率特性分配系统的不平衡功率,建立DCPF模型;用DCPF计算每一组控制变量对应的静态电压稳定裕度;用ACPSO进行最优控制变量组合的搜索,求取最大静态电压稳定裕度;ACPSO算法通过将混沌算法引入到粒子群优化中,克服单纯粒子群优化算法计算速度慢、有时易陷入局部最优解的缺点。算例验证了该算法的有效性。     

低酸性食品罐头的杀菌与P.A.3679菌

<正> 一、概述: 在pH大于4.6的低酸性食品罐头中,对公共卫生安全构成威胁的主要微生物要算是肉毒杆菌(Clostridium botulinum)了。它是食物中毒病原菌中耐热性最强的细菌,有A、B、C、D、E、F、G七种亚型,已知可产生强毒素并对人类健康造成危害的主要是A、B、E、F型。由于此种微生物在生长过程中产生外毒素,即使是含有微剂量毒素的食品,如果人误食后,也能中毒死亡。从1960到1976年以来的十七年间,肉毒中毒事件仅在美国就     

圆钢管混凝土梁柱节点有限元分析

本文用有限元软件Ansys对圆钢管混凝土柱—钢梁节点局部模型进行非线性分析,讨论了节点的应力传递机理,梁翼缘及钢管壁变形规律。     

圆钢管轻骨料混凝土轴压短柱的受力性能分析

目前国内对钢管混凝土的轴压短柱性能研究已经形成了较为成熟的模式,而对于轻型骨料的混凝土短柱性能研究则起步较晚,其研究也存在一定的局限性。研究成果中有的进行了钢管轻骨料混凝土轴压短柱和钢管混凝土相似性能的比对,结果显示在一定条件下破坏性差异较小;而某些研究则在钢管轻骨料混凝土轴压短柱试验的基础上进行了拓展,利用极限平衡法对其极限承载性能进行了推导;还有学者针对轻骨料混凝土轴压短柱试验中采用合成法进行了全过程的细     

Dual-demodulation large-scope high-sensitivity refractive index sensor based on twin-core PCF

In this paper, a refractive index (RI) sensor based on the twin-core photonic crystal fiber (TC-PCF) is presented. Introducing the rectangular array in the core area makes the PCF possible to obtain high birefringence and low confinement loss over the wavelength range from 0.6 μm to 1.7 μm. Therefore, the core region can enhance the interaction between the core mode and the filling material. We studied theoretically the evolution characteristics of the birefringence and operating wavelength corresponding to the strongest polarization point under the condition of filling the rectangular array with RI matching fluid range from 1.33 to 1.41. Simulation results reveal that the proposed TC-PCF has opposite evolutions of change rates between the B and wavelength, and the maximum RI sensing sensitivities of 1.809×10-2 B/RIU and 8 700 nm/RIU at low and high RI infill are obtained respectively, which means that the TC-PCF features of dual-parameter demodulation for the RI sensing can maintain a high refractive index sensing sensitivity within a large scope of RI ranging from 1.33 to 1.41. Compared with the results of single-parameter demodulation, it is an optimized method to improve the sensitivity of low refractive index sensors, which has great application potency in the field of biochemical sensing and detection.     

Intermodal interference based refractive index sensor employing elliptical core photonic crystal fiber

A refractive index (RI) sensor based on elliptical core photonic crystal fiber (EC-PCF) has been proposed. The asymmetric elliptical core introduces the polarization-dependent characteristics of the fiber core modes. The performances of intermodal interference between the intrinsic polarization fiber core modes are investigated by contrast in two interferometers based on the Mach-Zehnder (M-Z) and Sagnac interference model. In addition, the RI sensing characteristics of the two interferometers are studied by successively filling the three layers air holes closest to the elliptical core in the cladding. The results show that the M-Z interference between LP01 and LP11 mode in the same polarized direction is featured with the incremental RI sensing sensitivity as the decreasing interference length, and the infilled scope around the elliptical core has a weak correlation with the RI sensing sensitivity. Due to the high birefringence of LP11 mode, the Sagnac interferometer has better RI sensing performance, the maximum RI sensing sensitivity of 12 000 nm/RIU is achieved under the innermost one layer air holes infilled with RI matching liquid of RI=1.39 at the pre-setting EC-PCF length of 12 cm, which is two orders of magnitude higher than the M-Z interferometer with the same fiber length. The series of theoretical optimized analysis would provide guidance for the applications in the field of biochemical sensing.     

智能Agent技术在高校网络教育中的应用

近年来,我国对Agent技术的理论和应用进行了广泛的研究。Agent技术已经从科学研究开始进入实际应用阶段。本文介绍了Agent技术,详细探讨了智能Agent技术在高校网络教育中的应用。