复杂功能超高层建筑的结构设计挑战

0引言 总部位于美国纽约的宋腾添玛沙帝工程顾问有限公司(Thornton Tomasetti lnc.,简称TT),是一个专长大型复杂结构设计的公司,其凭借专业实力,参与了世界前20个超高层建筑中近一半项目的结构设计,包括已建成的中国台湾台北市的世界金融中心(即台北101)、马来西亚吉隆坡的双子石油大厦、上海的恒隆广场和正在建设中的上海中心、芝加哥螺旋塔、平安国际金融中心等。     

Mathematical programming for the scheduling problem with alternate process plans in FMS

The purpose of this research is to consider the operational scheduling problem and the determination of production routing with alternate process plans simultaneously such that the advantages of routing flexibility are expected. The problem is formulated by using 0–1 integer programming regarding to the performance measure of either the minimum of the absolute deviation of meeting due date or the minimum of total completion time. The approach of mathematical programming generates the optimal schedule, rather than near optimal schedule or a better schedule, to meet the selected criterion. Two mathematical formulation models developed are presented and an example is shown in this paper referring to the either one of performance criteria.     

Control of structure, morphology and property in electrospun poly(glycolide-co-lactide) non-woven membranes via post-draw treatments

Non-woven biodegradable membranes fabricated by electrospinning have recently attracted a great deal of attention for biomedical applications. In this study, microstructure, morphology and texture of electrospun poly(glycolide-co-lactide) (GA/LA: 90:10, PLA10GA90) non-woven membranes were investigated after post-draw and thermal treatments to tailor the degradation and mechanical properties. As-prepared electrospun PLA10GA90 membranes exhibited a low degree of crystallinity. When annealed at elevated temperatures without drawing, the membrane showed a higher degree of crystallinity with distinct lamellar structure but no overall orientation. The crystal orientation improved significantly when the membrane was drawn and annealed. As the elongation ratio increased, the degree of orientation and the tensile strength were increased. The corresponding tensile retention time was also increased from 2 to 12 days during in vitro degradation. Post-drawn and annealed membranes exhibited a slower degradation rate in the beginning of incubation, but a faster rate after two weeks of degradation when compared to as-spun membranes.     

Panel data analysis—advantages and challenges

We explain the proliferation of panel data studies in terms of (i) data availability, (ii) the more heightened capacity for modeling the complexity of human behavior than a single cross-section or time series data can possibly allow, and (iii) challenging methodology. Advantages and issues of panel data modeling are also discussed. This invited paper is discussed in the comments available at: , , , , , , , .     

High-power (200 mW) singlemode operation of InGaAsN/GaAs ridge waveguide lasers with wavelength around 1.3 /spl mu/m

High-power narrow ridge waveguide lasers emitting with a wavelength around 1.3 /spl mu/m were realised with a single In/sub 0.36/GaAsN/sub 0.022/ quantum well with GaAs barriers. A narrow vertical far-field angle of 35/spl deg/ was obtained. Single lateral mode continuous-wave operation with slope efficiency of 0.57 W/A, series resistance of 2.6 /spl Omega/, and kink-free output power of 210 mW was achieved.     

Efficient Transition Fault ATPG Algorithms Based on Stuck-At Test Vectors

This paper proposes novel algorithms for computing test patterns for transition faults in combinational circuits and fully scanned sequential circuits. The algorithms are based on the principle that s@ vectors can be effectively used to construct good quality transition test sets. Several algorithms are discussed. Experimental results obtained using the new algorithms show that there is a 20% reduction in test set size, test data volume and test application time compared to a state-of-the-art native transition test ATPG tool, without any reduction in fault coverage. Other benefits of our approach, viz. productivity improvement, constraint handling and design data compression are highlighted.     

The influence of water vapor on the fatigue crack propagation kinetics in pure aluminum single crystals

In general, water vapor accelerates the fatigue crack propagation rate in pure aluminum (99.999 pct) single crystals under Mode II or Mode I–II loading. This effect can be explained by the fact that hydrogen generated during corrosion fatigue enters into the specimen and is transported by dislocation sweeping during fatigue deformation from the surface to the interior of the crystal for a much longer distance than by diffusion. It is hydrogen which accelerates the fatigue crack propagation rate. However, for certain orientations, the reverse effect termedunusual retardation was observed, which can be explained by the blunting effect due to the presence of numerous microcracks along the secondary PSB.     

Health and safety aspects of irrigation of raw-eaten food crops with reused water

The Monterey Wastewater Reclamation Study for Agriculture (MWRSA) has Completed its first year of a five-year pilot effort to investigate and to demonstrate feasibility of food crop irrigation with reclaimed municipal effluent. The project comprises a 96-plot field trial for statistical comparison of three water treatments: an eight-hectare commercial scale farm for demonstration of water reclamation for growing lettuce, broccoli, cauliflower, celery, and artichokes; an aerosol study, a virus assay, market studies, and other ancillary investigations. First year results preliminarily indicate that the main hypothesis of the study will prove to be true, i.e. “raw-eaten food crops irrigated with properly treated municipal wastewater effluent are safe for human consumption”.     

A comparative study of the stress field around a reinforced and an unreinforced normal intersection of two cylindrical shells

The results of a comparative study of the effects of reinforcement on the stress fields in the critical intersection region of two normally intersecting cylindrical shells are presented. The results for in-plane and out-of-plane moments have been obtained experimentally by the use of electrical resistance foil gages, and numerically by the use of a three-dimensional finite element program. The finite element analysis also includes internal pressure loading. A comparison of results obtained by using a thin shell element with six degrees of freedom at each of the four nodes (three displacements and three rotations) and a three-dimensional element with three displacement degrees of freedom at each of the eight nodes, is also given.     

A fast-decoupled method for time-domain simulation of powerconverters

Fast long-term dynamic simulation of power converters is discussed. Because of switching actions, the converter can operate in different configurations and, therefore, it can be represented by a state-space time-varying linear system. This paper presents a new method for calculating switching time from an accurate and explicit form of the switching condition, hence the step-by-step search of the switching instant can be greatly simplified. In the proposed algorithm, a converter is partitioned into subsystems, which are simulated in a decoupled manner and coordinated through data exchange