A novel phenomenological model using a sine function for finite-element simulation of large-strain hot deformation

In hot deformation, the flow stress curves of steels always present as two typical types: at relatively high temperature and low strain rate, the flow stress may first increase and then attain a steady value without reaching an obvious peak stress; in other situations, the flow stress decreases after reaching peak stress and then attains a steady value. A new phenomenological model,described by a sine-function equation, is proposed to define the relationship between flow stress and deformation parameters. A series of isothermal compressions for a carbon steel were carried out, as a case study, to obtain basic experimental data.Parameters of the new model were sequentially determined. The predicted results of the proposed model were compared with actual measured data. Good accuracy was found in the standard statistical parameters of correlation coefficient, root mean square error, and average absolute relative error with the values of 0.935, 7.137 MPa and 4.352%, respectively. Discussion of applications of different models in finite-element simulation demonstrated the benefit of the new model. When comparing the simulation results of three different deformation patterns with large strain, the new model showed 10%–20% lower predicted forming load than the original Arrhenius equation, and better applicability and reliability than modified Arrhenius equations.     

地质雷达探测城市地下空洞案例分析

该文选取典型工程案例,从测区地质地貌、水文地质条件、地层岩性及地球物理特性等方面,分析总结了三维和二维地质雷达系统在城市道路地下空洞探测工作中的应用.经钻孔和孔内摄像验证,地质雷达探测效果良好,可为城市地质病害超前预报、风险评估和综合治理提供服务.     

NOSQL在WEB日志分析中的应用

本文主要分析NOSQL在WEB日志分析中的应用,使用MongoDB数据库和HadOOP进行系统架构,使用Map Reduce方法处理分析WEB日志数据。在WEB前台显示中,本文将WEB日志统计分为若干个核心模块,并使用jQuery技术进行WEBUI的设计。     

三维激光扫描技术应用于建筑物建模的测量方法研究

三维激光扫描技术是当前一种新技术,其应用领域广泛.提出三维激光扫描技术在建筑物模型建设中的应用方法,分别以不同类型的建筑物为例,研究了其具体测量方案,并对相关参数设置进行分析,通过实验该方法取得了较好的结果.     

混合动力车兼容CAN/K总线故障诊断适配器

以往,车辆上故障诊断设备都是通过车辆上OBD Ⅱ诊断座的K总线接口按照ISO9141协议与车辆上ECU进行通信获得相应数据。而在此混合动力车上,故障诊断适配器通过诊断座的CAN和K总线接口与车辆上ECU进行通信,然后通过RS232串口将数据传给PC机,最后PC机用户界面程序显示故障码等数据给用户。     

A polynomial time algorithm for GapCVPP in l1 norm

This paper concerns the hardness of approximating the closest vector in a lattice with preprocessing in l1norm,and gives a polynomial time algorithm for GapCVPPγin l1norm with gapγ=O(n/log n).The gap is smaller than that obtained by simply generalizing the approach given by Aharonov and Regev.The main technical ingredient used in this paper is the discrete Laplace distribution on lattices which may be of independent interest.     

城市化进程中的历史街区有机更新——以西宁东关清真大寺周边街区改造为例

在新型城镇化的背景下,为解决城市更新与开发过程中存在的城市文化空间遭到破坏、历史文脉被割裂及城市记忆消失等问题,研究提出应当重视城市的文化诉求,而不是用简单的大拆大建来稀释城市生活的本质。同时,结合西宁东关清真大寺周边街区的改造实践,研究从街区脉络构成的文化主因及规划原则方面出发,探寻在城市更新与开发的过程中应如何确定其文化身份和发展脉络,并以此作为指导街区更新改造的原则和价值取向,从而构建出延续地域文脉、保存邻里关系和满足当地居民需求的新街区。     

液压挖掘机回转减速机的特点及其开发

本文主要是介绍了液压挖掘机回转机构的特点及其开发中解决的问题。     

Adaptive decision-level fusion strategy for the fault diagnosis of axial piston pumps using multiple channels of vibration signals

An axial piston pump is a key component that plays the role of the “heart” in hydraulic systems. The pump failure will lead to an unexpected breakdown of the entire hydraulic system or even economic loss and catastrophic safety consequences. Several vibration-based machine learning methods have been developed to detect and diagnose faults of axial piston pumps. However, most of these intelligent diagnosis methods use single-sensor vibration data to monitor the pump health states. Additionally, the diagnostic accuracy is unacceptable in most situations due to the complex pump structure and limited sensor information. Therefore, this study proposes a multi-sensor fusion method to improve the fault diagnosis performance of axial piston pumps. The convolutional neural network receives three channels of vibration data and makes the final diagnosis through information fusion at the decision level. The proposed decision fusion method is evaluated on the classification task of leakage levels of an actual axial piston pump. The experimental results show that the proposed method improves the classification accuracy by adjusting the probability distribution of classification according to the learned weight matrix.

     

文脉视角下的城市空间营造策略——以佛山东平河一河两岸城市设计为例

在快速的城市化进程中,城市空间的单调化、低质化问题日益突出,原有的空间特色和尺度消失殆尽,其根源在于空间塑造脱离了城市的背景。延续城市文脉的城市设计,不仅是解决城市具体空间问题和矛盾的方法,更是构建美好城市空间、实现可持续发展的重要手段。佛山东平河一河两岸城市设计在对基地文脉的物质、精神要素进行梳理和分析的基础上,采用文脉撷取、移植和营造等方法,从文脉的视角出发,进行城市空间营造,这一设计思路有助于复兴城市文脉,可供参考和借鉴。