Development and Testing of a New Computerized Link Analysis System

Link analysis (LA) is a popular ergonomic tool for studying and improving the layout of workspaces. It uses a data (event) recording method to input interactions of human behavior with their environment. The traditional “pen and paper'' method of LA is cumbersome, time consuming, and gives limited outputs. To address these limitations, the computerized link analysis (CLA) system was developed and tested in laboratory and real‐world environments. CLA offers an integrated task analysis tool, including traditional LA functions (layout, event recording) with more detail for operator activities, time‐motion functions, and multioperator data recording. As well as the conventional LA results (link diagrams and link tables), there are additional outputs for time‐event lists (start/end time, duration, chronology, additional notes, importance, and operator ID), and processed link diagrams with the link direction and frequency. © 2012 Wiley Periodicals, Inc.     

Identification of the Elastic–Plastic Behavior of Adhesively Bonded Structures Under Multi-Axial Loadings: Comparison of a Modified Arcan Test and a Tension/Compression–Torsion Test

Structural bonding is nowadays widespread in the industry. However, characterisation methods and 3D modelling of the adhesives need to be improved. The characterisation requires an experimental procedure to obtain a large experimental database under various loading cases, which represents a significant amount of data. The 3D modelling requires advanced models with several parameters to identify and generally uses inverse identification procedures, which can be time expensive. For a good accuracy, the constitutive models need to take into account the dependency on the hydrostatic stress and be written under the non-associated formalism. In this study, the experimental database is obtained via a modified Arcan test that can cover a wide range of loadings between tension, shear, mixed tension–shear, and mixed compression–shear. A second experimental campaign is realized with a tension/compression–torsion (TCT) test that can cover a greater range of loadings: from tension to compression and mixed tension/compression–shear, with an infinite possibility of mixed loadings. The modified Arcan database is used to identify a 3D elastic–plastic Mahnken–Schlimmer type model, according to an inverse identification procedure developed in a previous study. This model identification is validated on the experimental database coming from the TCT test: a numerical/experimental comparison is realized. This allows the validation of the model and emphasizes the benefits of the TCT test. Indeed, it proves that this test is well suited to characterize adhesive joints and presents several capacities that will be really useful for further studies, like an infinite range of non-proportional loadings available.     

Exact 3D boundary representation in finite element analysis based on Cartesian grids independent of the geometry

This paper proposes a novel Immersed Boundary Method where the embedded domain is exactly described by using its Computer‐Aided Design (CAD) boundary representation with Non‐Uniform Rational B‐Splines (NURBS) or T‐splines. The common feature with other immersed methods is that the current approach substantially reduces the burden of mesh generation. In contrast, the exact boundary representation of the embedded domain allows to overcome the major drawback of existing immersed methods that is the inaccurate representation of the physical domain. A novel approach to perform the numerical integration in the region of the cut elements that is internal to the physical domain is presented and its accuracy and performance evaluated using numerical tests. The applicability, performance, and optimal convergence of the proposed methodology is assessed by using numerical examples in three dimensions. It is also shown that the accuracy of the proposed methodology is independent on the CAD technology used to describe the geometry of the embedded domain. Copyright © 2015 John Wiley & Sons, Ltd.     

Parametric Regionalism

Philip Yuan , Founding Director of Shanghai-based firm Archi-Union Architects, applies parametric techniques to his design and research in China. Here he explains how Parametricism can provide a highly adaptive and open approach to architectural knowledge and spatial organisation, accommodating regional variations in culture and environment, through an emphasis on local climate, materials and craft traditions.     

居住小区规划设计课程教学方法研究

本文介绍了大连理工大学居住小区规划设计课程提高教学质量的具体措施,通过改进设计地块给定方式,安排学生实地调研居住片区和优秀住区,体验居住生活,整合院校教学资源,增加户型选型、景观设计、技术设计、工程设计等方面专题讲座,加强教学管理,检查阶段设计成果等多种教学方法,实现全面提高学生居住小区规划设计水平的教学目标。     

滨江景观空间营造手法探讨——以宁波市滨江大道景观建设为例

以宁波市滨江大道景观建设为例,探讨滨江景观营造中所强调的绿色生态、以人为本、亲水空间、场地固有文化的挖掘与展示、景观与防洪的结合等手法,并描述各手法应用于宁波市滨江大道景观建设的实例,从自然、生态、运动、休闲及活力等方面对景观实例进行分析,打造亲水宜人、景观优美、环境舒适、健康活力的生态综合型滨江景观休闲带。     

流体传热场中的守恒定律及其解法

流体传热场[1,2]中的传热是自然过程或过程工业中常见的单元操作[3,4]之一,而套管式换热器[5]是一类典型的换热设备;在套管式换热器中的流体传热场涉及了流体运动[6],这些流体质点可能匀速直线运动(层流)、也可能波动运动(过渡流或湍流),所以确定流体质点运动的速度侧形(=■+■)成为了确定流体传热场的基础,本文中基于守恒定律探讨了流体质点运动速度侧形的求解方法。     

In-Situ,On-Demand Lubrication System for Space Mechanisms

Many of today's spaceraft have long mission lifetimes. Whatever the lubrication method selected, the initial lubricant charge is required to last the entire mission. Fluid lubricant losses are mainly due to evaporation, tribo-degradation, and oil creep out of the tribological regions.

In the past, several techniques were developed to maintain the appropriate amount of oil in the system. They were based on oil reservoirs (cartridges, impregnated porous parts), barrier films, and labyrinth seals. Nevertheless, all these systems have had limited success or have not established a proven record for space missions.

The system reported here provides to the ball-race contact fresh lubricant in-situ and on demand when the ball bearing is close to failure. The lubricant is stored in a porous cartridge attached to the inner or the outer ring of a ball bearing. The oil is released by heating the cartridge to eject oil, taking advantage of the greater thermal expansion of the oil compared to the porous network. The heating may be activated by torque increases that signal the depletion of oil in the contact. The low surface tension of the oil compared to the ball bearing material is utilized and the close proximity of the cartridge to the moving balls allows the lubricant to reach the ball-race contacts. This oil re-supply system avoided a mechanism failure, reduced torque to an acceptable level, and extended the life of the component.     

CRITICAL STRESS INTENSITY FACTORS FOR CRACKED HOLLOW PIPES UNDER TRANSIENT THERMAL LOADS

Finite element analyses of a long hollow cylinder having an axisymmetric circumferential internal edge crack, subjected to convective cooling on the inner surface are performed. The transient thermal stress intensity factor is estimated using a domain version of the J-integral method. The effect of the thickness of the cylinder, crack length, and heat transfer coefficient on the stress intensity factor history are studied. The variations of critical normalized stress intensity factor with crack length-to-thickness ratio for different parameters are presented. The results show that if a small inner surface crack begins to grow, its stress intensity factor will increase with increase in crack length, reach a maximum, and then begin to drop. Based on the results, a fracture-based design methodology for cracked hollow pipes under transient thermal loads is discussed.     

Solid Film Deposition and Non-Sacrificial Boundary Lubrication

This paper reports the results of studying various approaches in non-sacrificial boundary lubrication in which the deposition of a beneficial surface layer is the result of a chemical reaction involving one or more components in the lubricating fluid but not the metal surface itself. This is in contrast to the conventional approach which involves the rubbing surfaces as reactants with the components in the lubricant and usually promotes wear as the result of chemical change of the surfaces. The most interesting findings show that a reaction between a molybdenum complex and a mixture of zinc dialkylphosphorodithioates produced in situ deposition of MoS₂ and some other unidentified crystalline material. Effective reductions in friction and wear were obtained. Electron diffraction patterns of the worn metal surface established the presence of MoS₂.