Equivalent lateral force procedure for the seismic story drift design of tall frames using a hand‐calculated approach

The basic theory of the cantilever moment distribution method and the application of this method to conduct the equivalent lateral force procedure for the seismic design of tall frames are discussed in detail. Deflection–rotation formulas are introduced in this paper to determine the relative lateral story deflections and the joint rotations of laterally loaded rigid frames. An example is presented to conduct the seismic story drift design of a multistory, multi‐bay, moment‐resisting reinforced concrete frame using the cantilever moment distribution method and the deflection–rotation formulas developed in this paper. The hand‐calculated approach presented in the example can be used as a rapid and accurate method to determine the story drift for any laterally loaded multistory, multi‐bay rigid frames that are composed of identical single‐bay symmetrical bents. The following are the advantages of using this rapid approach: (1) this approach can be carried out by using hand calculations only (without the use of computer computations); (2) the results obtained from this approach are as accurate as those derived from the traditional moment distribution and the slope deflection methods; and (3) the results obtained from this approach can be used to verify the accuracy of the results obtained from computer computations. Copyright © 2005 John Wiley & Sons, Ltd.     

The evaluation of domain integrals in complex multiply-connected three-dimensional geometries for boundary element methods

The treatment of domain integrals has been a topic of interest almost since the inception of the boundary element method (BEM). Proponents of meshless methods such as the dual reciprocity method (DRM) and the multiple reciprocity method (MRM) have typically pointed out that these meshless methods obviate the need for an interior discretization. Hence, the DRM and MRM maintain one of the biggest advantages of the BEM, namely, the boundary-only discretization. On the other hand, other researchers maintain that classical domain integration with an interior discretization is more robust. However, the discretization of the domain in complex multiply-connected geometries remains problematic. In this research, three methods for evaluating the domain integrals associated with the boundary element analysis of the three-dimensional Poisson and nonhomogeneous Helmholtz equations in complex multiply-connected geometries are compared. The methods include the DRM, classical cell-based domain integration, and a novel auxiliary domain method. The auxiliary domain method allows the evaluation of the domain integral by constructing an approximately C ¹ extension of the domain integrand into the complement of the multiply-connected domain. This approach combines the robustness and accuracy of direct domain integral evaluation while, at the same time, allowing for a relatively simple interior discretization. Comparisons are made between these three methods of domain integral evaluation in terms of speed and accuracy. This work was partially supported by the United States Department of Energy (DOE) grants DE-FG03-97ER14778 and DE-FG03-97ER25332. This financial support does not constitute an endorsement by the DOE of the views expressed in this paper.     

Adaptive joint beamforming and B‐MMSE detection for CDMA signal reception under multipath interference

The combination of antenna array beamforming with multiuser detection can effectively improve the detection efficiency of a wireless system under multipath interference, especially in a fast‐fading channel. This paper studies the performance of an adaptive beamformer incorporated with a block‐wise minimum mean square error(B‐MMSE) detector, which works on a unique signal frame characterized by training sequence preamble and data blocks segmented by zero‐bits. Both beam‐former weights updating and B‐MMSE detection are carried out by either least mean square (LMS) or recursive least square (RLS) algorithm. The comparison of the two adaptive algorithms applied to both beamformer and B‐MMSE detector will be made in terms of convergence behaviour and estimation mean square error. Various multipath patterns are considered to test the receiver's responding rapidity to changing multipath interference. The performance of the adaptive B‐MMSE detector is also compared with that of non‐adaptive version (i.e. through direct matrix inversion). The final performance in error probability simulation reveals that the RLS/B‐MMSE scheme outperforms non‐adaptive B‐MMSE by 1–5 dB, depending on the multipath channel delay profiles of concern. The obtained results also suggest that adaptive beamformer should use RLS algorithm for its fast and robust convergence property; while the B‐MMSE filter can choose either LMS or RLS algorithm depending on antenna array size, multipath severity and implementation complexity. Copyright © 2004 John Wiley & Sons, Ltd.     

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.     

A new model for the performance evaluation of synchronous circuitswitched multistage interconnection networks

Patel (1981) proposed a probabilistic approach to analyze the performance of synchronous multistage interconnection networks (MINs) based on a uniform reference model and the assumption of independent requests. Patel's model and analytical results have been widely adopted by numerous researchers as a basis to investigate various aspects of MINs. We study in detail the effects of the independence assumption on the accuracy of system performance and point out the factors which cause an inaccuracy. A new queueing model is then proposed and is shown to be very accurate. Since only six states are needed, independent of the size of MINs, this new model is very efficient computationally     

Silhouette-based human pose estimation using reversible jump Markov chain Monte Carlo

A novel approach for recovering the human body configuration based on the silhouette is presented. By considering pose inference as traversing the difference subspaces and using a data-driven mechanism, reversible jump Markov chain Monte Carlo (RJMCMC) can explore such solution space very efficiently. Experimental results are provided to demonstrate the efficiency and effectiveness of the proposed approach.     

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.     

Supercritical CO2 extraction of phthalate plasticizers from PVC

Three common phthalates, namely, dioctyl phthalate, diisodecyl phthalate, and trioctyl trimellitate, were used as plasticizers for poly(vinyl chloride) (PVC) processing, and the extraction of these plasticizers were investigated using supercritical CO₂ fluids. Factors affecting the extractions of these phthalates were focused. The molecular weight of phthalates was found to dominate the level of extraction of low temperatures, whereas the content of carbonyl groups in the phthalate was a determining factor for the level of extraction of high temperatures. Negligible extraction was observed below the critical pressure of CO₂. For 32°C, the level of the extraction is insignificant below density of ca 0.7 g/cm³, above which the level of the extraction increases roughly linearly with increasing density. For temperatures above 32°C, the density of CO₂ for apparent extractions decreased with increasing temperatures. The threshold density of CO₂ for extractions was found to be independent of the amount of a given phthalate in PVC. Two extraction rates during the extraction could be determined, with a higher rate in the first hour followed by a lower rate later in the extraction for all three phthalates. The effects of the extractions of phthalates on the flexibility of PVC were also investigated as well as the effects of the extrusion conditions, which could lead to various degrees of plasticization of PVC, on the level of extractions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4032–4037, 2003     

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: , , , , , , , .     

Success-driven learning in ATPG for preimage computation

Unbounded model checking fundamentally requires either image or preimage calculations. We introduce a hybrid method for making preimage calculations using ATPG and binary decision diagrams (BDDs). Experimental results show that the proposed method achieves a speedup of two to three orders of magnitude over pure ATPG methods.