堤坝涵管接触冲刷破坏模式分析

本文分析总结了涵管与堤坝土体结合面区域土体渗透变形或接触冲刷破坏影响因素,主要包括涵管材料、裂缝或孔洞、回填土性质、水头、水流类型、设计因素等。从后向侵蚀管涌和内部侵蚀机理出发,归纳了4种堤坝涵管接触冲刷破坏模式,即土颗粒流失进入无压涵管导致土体发生内部侵蚀、压力涵管内水外溢导致的内部侵蚀、沿涵管周围土体产生后向侵蚀管涌或内部侵蚀和涵管附近土体裂缝导致的内部侵蚀。应用连续统概念模型阐述了接触冲刷破坏发生发展过程和可能防御措施,有助于堤坝涵管工程设计、施工和后期运行管理。     

水溶性维纶纤维的性能测试与分析

对水溶性维纶纤维进行性能测试,并和普通维纶纤维进行对比.结果表明:不同水溶温度的水溶性维纶纤维的纵向形态基本相似,较平直光滑,而普通维纶纤维纵向有明显沟槽;水溶性维纶纤维和普通维纶纤维的红外光谱基本相同,表现出维纶纤维的典型特征谱带,水溶性维纶纤维产生较强的H—O—H吸收带;水溶性维纶纤维的断裂强度小于普通维纶纤维,断裂伸长率大于普通维纶纤维;水溶性维纶纤维的卷曲数、卷曲率、卷曲回复率、卷曲弹性率略高于普通维纶纤维;随着水浴温度的升高,水溶性维纶纤维的溶解程度提升.     

煤直接液化催化剂研究进展

综述了煤直接液化中催化剂的研究,开发,催化机理等方面的进展,重点介绍了超微高分散性催化剂,微生物酶催化剂以及煤—废弃塑料共催化液化催化剂的研究进展情况,并指出了当前新型高效催化剂的开发动向。     

废砂/PE废地膜复合材料热老化性能的研究

以聚乙烯(PE)废地膜和工业废砂为原料,制备了不同配比的废砂/PE废地膜复合材料,研究了PE基体和复合材料的热老化规律。研究发现,经80℃人工加速热老化处理后,复合材料的玻璃化转变温度(Tg)随老化时间的增加而降低;一定条件下的热老化有助于加强PE基体和废砂间的界面作用,使复合材料的力学性能先升高后降低;废砂的加入有利于PE废地膜热老化性能的提高。     

直升机操纵台的BIT功能设计

为了提高系统的易测试性,保证飞行安全,在该直升机操纵台硬件设计中,针对各个功能模块的特点,相应地采用了多种BIT(Build-in Test,机内测试)技术,如余度BIT、环绕BIT等技术,并在微控芯片软件中嵌入了自检测模块,全面完整地实现了系统的自检测;同时利用扩展flash存储芯片实时保存系统运行数据和测试信息,可通过串口上传至上位机,为故障分析提供了便利;采用Visual C++编程语言,结合专家系统开发了一套上位机检测软件,用于操纵台故障的智能诊断。     

Magnetoelectric transducer with high quality factor for wireless power receiving

To achieve strong power coupling, a resonance-type magnetoelectric (ME) transducer with high quality factor is developed to achieve strong ME coupling. The ME transducer employs a type of iron–nickel-based ferromagnetic alloy with constant elasticity and piezoelectric Pb(Zr,Ti)O₃ (PZT8) material. The dynamic magnetomechanical behavior of the ferromagnetic alloy is investigated. The result indicates that the strain coefficient of the ferromagnetic alloy at resonance achieves 557.07 nm/A due to the high effective mechanical quality factor of the alloy. The transducer is designed to operate as a half-wavelength, longitudinal resonator. The dynamic performance of the transducer is evaluated by measuring its electrical and vibrational characteristics. The results reveal that (1) the resonance of the transducer occurs at the frequency of 26.9336 kHz with a strain coefficient of 314.74 nm/A, an effective mechanical quality factor of 1600; (2) the ME voltage coefficient achieves 30.07 V/Oe (i.e., 375.875 V/cm Oe) at resonance; (3) the ME output power density at optimal load resistance of 25 kΩ achieves 0.956 mW/cm³ under 0.3 Oe root-mean-square AC magnetic field. The performances indicate that the transducer is promising for ME energy conversion application.     

Thermal assisted direct bonding between structured glasses for lab-on-chip technology

A thermal assisted direct bonding (TADB) technique between structured glasses is proposed for micro-fluidic device fabrication. The bonded glass pairs were characterized by optical microscopy, scanning electron microscopy (SEM), apparent shear strength tests and Vickers hardness measurements across the bonded interface. The optimisation of TADB parameters on flat glasses and on structured glasses was analysed. This technique is user-friendly and low cost, and can be considered for mass production of glass-based micro-fluidic devices.     

PowerBuilder环境下异种数据库应用系统集成的实现方法

以一个CIMS系统集成开发过程为实例,提出了PowerBuilder环境下通过专用接口和ODBC的连接方式,进行异种数据库应用系统信息集成的实现方法。     

基于精益供应链的工程建设项目价值分析

结合精益供应链理论,以价值作为方案决策要点,对工程建设项目价值分析进行研究,通过案例说明价值分析在工程建设项目中的应用流程。采用模糊质量功能展开法综合评价各方案的价值,并进行对比分析,找出价值最优方案。基于精益供应链的工程建设项目价值分析是一种行之有效的方案决策方法。     

Nonlinear inverse optimization approach for determining the weights of objective function in standing reach tasks

This paper presents a nonlinear inverse optimization approach to determine the weights for the joint displacement function in standing reach tasks. This inverse optimization problem can be formulated as a bi-level highly nonlinear optimization problem. The design variables are the weights of a cost function. The cost function is the weighted summation of the differences between two sets of joint angles (predicted posture and the actual standing reach posture). Constraints include the normalized weights within limits and an inner optimization problem to solve for joint angles (predicted standing reach posture). The weight linear equality constraints, obtained through observations, are also implemented in the formulation to test the method. A 52 degree-of-freedom (DOF) human whole body model is used to study the formulation and visualize the prediction. An in-house motion capture system is used to obtain the actual standing reach posture. A total of 12 subjects (three subjects for each percentile in stature of 5th percentile female, 50th percentile female, 50th percentile male and 95th percentile male) are selected to run the experiment for 30 tasks. Among these subjects one is Turkish, two are Chinese, and the rest subjects are Americans. Three sets of weights for the general standing reach tasks are obtained for the three zones by averaging all weights in each zone for all subjects and all tasks. Based on the obtained sets of weights, the predicted standing reach postures found using the direct optimization-based approach have good correlation with the experimental results. Sensitivity of the formulation has also been investigated in this study. The presented formulation can be used to determine the weights of cost function within any multi-objective optimization (MOO) problems such as any types of posture prediction and motion prediction.