分期围护桩对不设缝的地铁接口受力影响分析

对分期实施且不设变形缝的地铁明挖区间主体与外挂结构的接口进行受力计算,分析了接口处分期围护桩对接口受力的影响,提出了类似工程设计的要点。同时,基于计算结果及工程实际,参考现有研究成果,提出了当接口采用不设变形缝的方式连接时,提高接口处施工缝抗剪承载力及连接质量的施工措施。

导纳型力觉接口的透明性力觉交互研究

提出了一种面向导纳型力觉接口设备透明性优化的自适应人机力觉交互算法,在基于速度环力前馈PI控制器基础上引入了接触刚度在线辨识及迭代修正.构造了该自适应控制律作用下系统稳定性的判定函数,证明了当力觉接口的速度环渐进无差时控制器具有全局稳定性.力觉接口设备与固定刚度环境接触以及与操作者随机交互的实验结果表明,控制算法能够自适应操作者与力觉接口之间的抓握刚度变化,在保证稳定性的同时有效提高力觉交互过程的透明性.

一种新型导纳力觉交互设备的研究

提出一种导纳型力觉接口设备,利用摩擦轮原理进行传动,其低惯量、高速等特点保证了力觉系统具有较高出力带宽。同时,以设备为平台建立了人机力觉交互系统,进行了力觉交互实验。

汽(气)缸稳定性计算程序GUI设计

介绍汽(气)缸稳定性的通用计算方法,阐述汽(气)缸接口力及力矩的合成与分解。设计计算程序流程图,基于该流程图在MATLAB环境下完成了汽(气)缸稳定性计算程序GUI设计。实例验证,该GUI界面使用方便,计算精度满足工程需要。

复铰式100%低地板车辆结构强度分析方法研究

针对复铰式100%低地板车辆强度校核复杂,设计反馈周期长的问题,首先提出了模块分离和接口力的概念,根据车体模块、铰接件、转向架受力的特点,建立了车体在给定工况下的平衡方程,计算得到车体各模块之间以及车体与转向架之间的接口力数值。基于该方法计算了车钩压缩工况下拖车模块的结构强度;从模型处理与计算规模、计算结果和计算效率三个方面,将单模块计算法与整车有限元计算法进行了对比。结果表明,单模块法大大简化了有限元模型,且应力分布与数值几乎一致,由于计算规模仅为整车有限元法的1/5,在不影响计算精度的情况下,其计算效率有了极大的提高,该方法可很好地用于车辆结构的前期设计以及后期的强度校核。

大型板式换热器接管优化设计

基于隔压换热站供热面积大、管径大、压力高、温度高等特点,结合具体工程,利用CAESARⅡ应力分析软件,对热力站的布置方案进行了优化,从而降低了管道及换热器管口的应力,高效率、高质量地完成了设计工作。

TYJL-ECC新一代容错计算机联锁系统的研究

新一代计算机联锁系统不仅应具有高安全性、可靠性、实时性、可维护性、可用性等基本特性, 还应具有强大快速的处理能力、强大的接口结合能力和灵活的接口网络通信方式, 以适应高速铁路、快速客运专线、铁路信号一体化的发展趋势。介绍了满足这些要求的TYJL- ECC新一代容错计算机联锁系统的原理、软件体系结构和系统特点。

Comparison of explosive welding of pure titanium/SUS 304 austenitic stainless steel and pure titanium/SUS 821L1 duplex stainless steel

Pure commercial titanium was welded with two types of stainless steel,namely SUS 304 austenitic stainless steel and SUS 821L1 duplex stainless steel.The wavy interface of SUS 821L1 was smaller than that of SUS 304.The vortex zone was observed from both longitudinal and transverse directions,and its composition was analyzed.The interface of Ti/SUS 821L11 was able to bear 401−431 MPa shear load while that of Ti/SUS 304 could withstand 352−387 MPa.The weldability window was used to analyze experimental phenomenon.Furthermore,the smoothed particle hydrodynamics(SPH)numerical simulation method was used to simulate the wavy interface.The trend of wavelength and amplitude change with strength and the stand-offs was consistent with the experimental results.

Partial transient-liquid-phase bonding of TiC cermet to stainless steel using impulse pressuring with Ti/Cu/Nb interlayer

Partial transient liquid phase （PTLP） bonding of TiC cermet to 06Cr19Ni10 stainless steel was carried out. Impulse pressuring was used to reduce the bonding time, and a Ti/Cu/Nb interlayer was employed to alleviate the detrimental effect of interfacial reaction products on the bonding strength. Successful bonding was achieved at 885℃ under a pulsed pressure of 2-10 MPa within durations in the range of 2-8 min, which was notably shortened in comparison with conventional PTLP bonding. Microstructure characterization revealed the o- phase with a limit solubility of Nb, a sequence of Ti-Cu intermetallic phases and solid solutions of Ni and Cu in α＋β Ti in the reaction zone. The maximum shear strength of 106.7 MPa was obtained when the joint was bonded for 5 rain, indicating that a robust metallurgical bonding was achieved. Upon shear loading, the joints fractured along the Ti-Cu intermetallics interface and spread to the interior of TiC cermet in a brittle cleavage manner.

FORWARD GATED-DIODE METHOD FOR EXTRACTING HOT-CARRIER-STRESS-INDUCED BACK INTERFACE TRAPS IN SOI/NMOSFETs

The forward gated-diode R-G current method for extracting the hot-carrier-stress-induced back interface traps in SOI/NMOSFET devices has been demonstrated in this letter. This easy and accurate experimental method directly gives the induced interface trap density from the measured R-G current peak of the gated-diode architecture. An expected power law relationship between the induced back interface trap density and the accumulated stress time has been obtained.

铁法三台子二井井底车场巷道翻修

针对铁法三台子二井井底车场巷道变形破坏的特点 ,从设计和施工两方面入手 ,采取综合措施 ,有效地阻止了巷道变形。对巷道变形破坏原因进行了分析 。

Fatigue life evaluation of girth butt weld within welded cast steel joints based on the extrapolation notch stress method

The fatigue life evaluation of the girth butt weld within the welded cast steel joint was studied based on the extrapolation notch stress method.Firstly,the mesh sensitivity of the finite element model of the welded cast steel joint was analyzed to determine the optimal mesh size.Based on the stress field analysis of the finite element model of the welded cast steel joint at the weld toe and weld root,the sharp model of the extrapolation notch stress method was applied to derive the effective notch stress of the rounded model belonging to the effective notch stress method,in which the key problem is to calculate the extrapolation point C,and the extrapolation point C has an exponential function relationship with the geometric parameters of the welded cast steel joint.By setting different values of geometric parameters,the corresponding value of parameter C is calculated,and then the functional relationship between the extrapolation point C and the geometric parameters can be obtained by the multiple linear regression analysis.Meanwhile,the fatigue life evaluation of the girth butt weld within welded cast steel joints based on the effective notch stress was performed according to the guideline recommended by the IIW(International Institute of Welding).The results indicate that the extrapolation notch stress method can effectively simplify the process of calculating the effective notch stress and accurately evaluate the fatigue life of the girth butt weld within welded cast steel joints.

A plasticity model for sand-structure interfaces

The predictive capacity of numerical analyses in geotechnical engineering depends strongly on the efficiency of constitutive models used for modeling of interfaces behavior.Interfaces are considered as thin layers of the soil adjacent to structures boundary whose major role is transferring loads from structures to soil masses.An interface model within the bounding surface plasticity framework and the critical state soil mechanics is presented.To this aim,general formulation of the interface model according to the bounding surface plasticity theory is described first.Similar to granular soils,it has been shown that the mechanical behavior of sand-structure interfaces is highly affected by the interface state that is the combined influences of density and applied normal stress.Therefore,several ingredients of the model are directly related to the interface state.As a result of this feature,the model is enabled to distinguish interfaces in dense state from those in loose state and to provide realistic predictions over wide ranges of density and normal stress values.In evaluation of the model,a reasonable correspondence between the model predictions and the experimental data of various research teams is found.

Power Electronic Interface with Islanding Detection and Unbalanced Fault Ride-through Capability

Power electronic interface of dispersed generation plays a very important role in connecting a dispersed generation with utility grids. A power electronic interface not only adjusts the amount of active and reactive power injecting into a grid but also implements other importance duties as well. In this study, negative-sequence current injection has been fulfilled in three-phase power electronic interface for two important duties besides injecting reference power into utility grids. The first one is for islanding detection, and the other one is to enhance unbalance-fault ride-through capability of dispersed generation. This paper introduces a mechanism of negative-sequence injection based on controlling two separate coordinates of dq-control and explains the effect of negative-sequence injection in limiting the unbalanced currents generated from a dispersed generation. Using adaptive notch filter as a signal processing unit for the three-phase system, negative-sequence components are observed. The performance of entire control system is evaluated by time domain simulations, PSCAD/EMTDC （power systems computer aided design/electromagnetic transients including DC）.

Influence of construction interfaces on dynamic characteristics of roller compacted concrete dams

To study the influence of construction interfaces on dynamic characteristics of roller compacted concrete dams(RCCDs),mechanical properties of construction interfaces are firstly analyzed. Then, the viscous-spring artificial boundary(VSAB) is adopted to simulate the radiation damping of their infinite foundations, and based on the Marc software, a simplified seismic motion input method is presented by the equivalent nodal loads. Finally, based on the practical engineering of a RCC gravity dam, effects of radiation damping and construction interfaces on the dynamic characteristics of dams are investigated in detail. Analysis results show that dynamic response of the RCC gravity dam significantly reduces about 25% when the radiation damping of infinite foundation is considered. Hot interfaces and the normal cold interfaces have little influence on the dynamic response of the RCC gravity dam.However, nonlinear fracture along the cold interfaces at the dam heel will occur under the designed earthquake if the cold interfaces are combined poorly. Therefore, to avoid the fractures along the construction interfaces under the potential super earthquakes,combination quality of the RCC layers should be significantly ensured.

The Rise and Fall of Social Networking Sites： A Comparative Study of Cyworld and Facebook

This study examines why some social networking sites （SNSs） stagnate while other SNSs grow by comparing Cyworld with Facebook. Cyworld was one of the most successful SNSs in the world, but its international expansion efforts failed. Facebook＇s open technology has had considerable influence on various sectors of the economy and society and allowed it to become a dominant SNS at the global level, whereas Cyworld has remained a local SNS. Facebook＇s open platform and application programming interface （API） pose a serious challenge to Cyworld＇s walled-garden approach. Cyworld is based on strong ties fostering close relationships, whereas Facebook expands social networks through its open and weak ties and has more network power than Cyworld. Therefore, openness is the main reason behind the rise of Facebook and the fall of Cyworld.

Design principle for parameters and interferences of tungsten carbide insert interface on roller bits

The lifetime of roll-bits with inserted tooth will be obviously decreased while drilling in strata and the tungsten carbide can be integrally separated from the roll-cone,which will need more trip out time to replace the roller bit.This study provides an entire analysis on stress as well as strength for teeth and tooth holes in loaded conditions.Qualities of tooth drop from matrix within roller bit.The optimized interferences of teeth inserted into the bit can be reasonably obtained by the critical interference derived from some relevant influence factors on the tooth-fixing quality of roller bits.

On Hybrid Computer-Aided Tools to Interface Design Data

Recognizing the drawbacks of stand-alone computer-aided tools in engineering, several hybrid systems are suggested with varying degree of success. In transforming the design concept to a finished product, in particular, smooth interfacing of the design data is crucial to reduce product cost and time to market. Having a product model that contains the complete product description and computer-aided tools that can understand each other are the primary requirements to achieve the interfacing goal. This article discusses the development methodology of hybrid engineering software systems with particular focus on application of soft computing tools such as genetic algorithms and neural networks. Forms of hybridization options are discussed and the applications are elaborated using two case studies. The forefront aims to develop hybrid systems that combine the strong side of each tool, such as, the learning, pattern recognition and classification power of neural networks with the powerful capacity of genetic algorithms in global search and optimization. While most optimization tasks need a certain form of model, there are many processes in the mechanical engineering field that are difficult to model using conventional modeling techniques. The proposed hybrid system solves such difficult-to-model processes and contributes to the effort of smooth interfacing design data to other downstream processes.

Oscillation analysis of a DFIG-based wind farm interfaced with LCC-HVDC

With the increasing capacity of wind farm, HVDC technology has become a promising transmission scheme for long distance transportation of large-scale wind power. However oscillation caused by this system will have a great influence on the security and stability of power system operation. In this paper, the oscillation of a doubly-fed induction generator(DFIG)-based wind farm interfaced with line commutated converter(LCC) based HVDC is discussed. Low-frequency oscillation and subsynchronous oscillation(SSO) are studied since these two oscillations are the particularly concerned oscillations in the stability study of power system in recent years. The model of a DFIG-based wind farm interconnected with LCC-HVDC is developed. The impact of drive train model's structure and parameters on the oscillation characteristics is analyzed. Eigenvalue and participation factor analysis are used to identify the three main modes, which include controller mode, electromechanical mode, and shaft mode. The effects of DFIG controller's parameters, wind speed and operating conditions of HVDC on those modes are studied. Electromagnetic transient simulations are performed to verify the results of the eigenvalue analysis.

Particle Size Influence on the Effective Permeability of Composite Materials

The energy method, which estimates the effective permeability of composite material is proposed. We approximate the effective static magnetic permeability by energy method and Maxwell-Garnett method for spherical particles dispersing system. Considering the effect of the interface layer between the medium and the particle, we study the nanoparticles embedded in a medium exactly. The interface layer property plays a significant factor for the effective permeability of the composite material in which nano-sized particles embedded.