Estimation of Length Limits for Integral Bridges Built on Clay

In this paper, the maximum length limits for integral bridges built on clay are determined as a function of the ability of steel H-piles supporting the abutments to sustain thermal-induced cyclic displacements and the flexural capacity of the abutment. First, H-pile sections that can accommodate large plastic deformations are determined considering their local buckling instability. Then, a low-cycle fatigue damage model is used to determine the maximum cyclic deformations that such piles can sustain. Next, nonlinear static pushover analyses of two typical integral bridges are conducted to study the effect of various geometric, structural, and geotechnical parameters on the performance of integral bridges subjected to uniform temperature variations. Using the pushover analyses results, design guidelines are developed to enhance and determine the maximum length limits for integral bridges built on clay. It is recommended that the maximum length of concrete integral bridges be limited to 210 m (689 ft) in cold climates and 260 m (853 ft) in moderate climates and that of steel integral bridges be limited to 120 m (394 ft) in cold climates and 180 m (590 ft) in moderate climates.     

SNR bounds of FSO links and its evaluation for selected beams

We formulate the signal-to-noise ratio (SNR) for free-space optical links. Upon inserting typical operating parameters, it is seen that SNR well approximates to the inverse of aperture averaged scintillation parameter. By adopting a common source beam power of 10 mW, we select three different source sizes of Gaussian, annular Gaussian (AG), and cosh-Gaussian beams. We then evaluate the SNR of these beams. Our results indicate that when fixed aperture opening is used, fully and partially coherent beams yield almost the same SNR performance. On the other hand, however, focusing and lowering wavelength of operation appear to be quite instrumental in improving the SNR performance. In this context, medium-sized AGB seems to exhibit the best performance.     

Behavior of square concrete columns reinforced with Prefabricated Cage System

Behavior of normal strength concrete columns reinforced with a new reinforcement, termed Prefabricated Cage System (PCS) is investigated. A total of 16 small-scale PCS and rebar reinforced column specimens were constructed and tested under monotonic axial displacement. The experimental results indicate that the overall behavior of rebar and PCS reinforced specimens are comparable prior to achieving the peak column load. In general, PCS specimens are more ductile and absorb more energy than similar rebar specimens after the peak load is reached. The effect of different parameters, such as the steel tube thickness, number of longitudinal reinforcements, transverse steel spacing, and crossties on the specimens’ strength and deformation capacity are investigated. A confined concrete model is proposed and used to predict the load–displacement response. The theoretical load–displacement relations obtained from the proposed model are compared with those obtained from the Mander et al. (J Struct Eng 114(8):1804–1826, 1988) confinement model.     

Estimation of missing observations in two‐level split‐plot designs

Inserting estimates for the missing observations from split‐plot designs restores their balanced or orthogonal structure and alleviates the difficulties in the statistical analysis. In this article, we extend a method due to Draper and Stoneman to estimate the missing observations from unreplicated two‐level factorial and fractional factorial split‐plot (FSP and FFSP) designs. The missing observations, which can either be from the same whole plot, from different whole plots, or comprise entire whole plots, are estimated by equating to zero a number of specific contrast columns equal to the number of the missing observations. These estimates are inserted into the design table and the estimates for the remaining effects (or alias chains of effects as the case with FFSP designs) are plotted on two half‐normal plots: one for the whole‐plot effects and the other for the subplot effects. If the smaller effects do not point at the origin, then different contrast columns to some or all of the initial ones should be discarded and the plots re‐examined for bias. Using examples, we show how the method provides estimates for the missing observations that are very close to their actual values. Copyright © 2007 John Wiley & Sons, Ltd.     

Approximate and exact hybrid algorithms for private nearest-neighbor queries with database protection

Mobile devices with global positioning capabilities allow users to retrieve points of interest (POI) in their proximity. To protect user privacy, it is important not to disclose exact user coordinates to un-trusted entities that provide location-based services. Currently, there are two main approaches to protect the location privacy of users: (i) hiding locations inside cloaking regions (CRs) and (ii) encrypting location data using private information retrieval (PIR) protocols. Previous work focused on finding good trade-offs between privacy and performance of user protection techniques, but disregarded the important issue of protecting the POI dataset D. For instance, location cloaking requires large-sized CRs, leading to excessive disclosure of POIs (O(|D|) in the worst case). PIR, on the other hand, reduces this bound to \(O(\sqrt{|D|})\), but at the expense of high processing and communication overhead. We propose hybrid, two-step approaches for private location-based queries which provide protection for both the users and the database. In the first step, user locations are generalized to coarse-grained CRs which provide strong privacy. Next, a PIR protocol is applied with respect to the obtained query CR. To protect against excessive disclosure of POI locations, we devise two cryptographic protocols that privately evaluate whether a point is enclosed inside a rectangular region or a convex polygon. We also introduce algorithms to efficiently support PIR on dynamic POI sub-sets. We provide solutions for both approximate and exact NN queries. In the approximate case, our method discloses O(1) POI, orders of magnitude fewer than CR- or PIR-based techniques. For the exact case, we obtain optimal disclosure of a single POI, although with slightly higher computational overhead. Experimental results show that the hybrid approaches are scalable in practice, and outperform the pure-PIR approach in terms of computational and communication overhead.     

基于形态分析的现代维吾尔语名词词干识别研究

现代维吾尔语名词词干识别是自然语言处理领域的重要基础性研究,主要目的是从句子中提取名词词干,提高名词识别效率。首先陈述形态分析概念,通过这些形态特征可以准确地识别其词性的意义;其次讨论维吾尔语的词类划分标准、名词的形态特征分析,总结词缀歧义及消解规则;该文提出研究总体思路,设计现代维吾尔语新词中名词识别算法,其中包括特征选择及参数估计、词内部特征、前后依存词特征等;最后将初中、高中物理维吾尔语教材作为验证对象,对名词词干进行统计与分析。     

Review and comparative evaluation of symbolic dynamic filtering for detection of anomaly patterns

Symbolic dynamic filtering (SDF) has been recently reported in literature as a pattern recognition tool for early detection of anomalies (i.e., deviations from the nominal behavior) in complex dynamical systems. This paper presents a review of SDF and its performance evaluation relative to other classes of pattern recognition tools, such as Bayesian Filters and Artificial Neural Networks, from the perspectives of: (i) anomaly detection capability, (ii) decision making for failure mitigation and (iii) computational efficiency. The evaluation is based on analysis of time series data generated from a nonlinear active electronic system. This work has been supported in part by the U.S. Army Research Laboratory and the U.S. Army Research Office under Grant No. W911NF-07-1-0376, by the U.S. Office of Naval Research under Grant No. N00014-08-1-380, and by NASA under Cooperative Agreement No. NNX07AK49A.     

ASRSM: A Sequential Experimental Design for Response Surface Optimization

Most preset response surface methodology (RSM) designs offer ease of implementation and good performance over a wide range of process and design optimization applications. These designs often lack the ability to adapt the design on the basis of the characteristics of application and experimental space so as to reduce the number of experiments necessary. Hence, they are not cost‐effective for applications where the cost of experimentation is high or when the experimentation resources are limited. In this paper, we present an adaptive sequential response surface methodology (ASRSM) for industrial experiments with high experimentation cost, limited experimental resources, and high design optimization performance requirement. The proposed approach is a sequential adaptive experimentation approach that combines concepts from nonlinear optimization, design of experiments, and response surface optimization. The ASRSM uses the information gained from the previous experiments to design the subsequent experiment by simultaneously reducing the region of interest and identifying factor combinations for new experiments. Its major advantage is the experimentation efficiency such that for a given response target, it identifies the input factor combination (or containing region) in less number of experiments than the classical single‐shot RSM designs. Through extensive simulated experiments and real‐world case studies, we show that the proposed ASRSM method outperforms the popular central composite design method and compares favorably with optimal designs. Copyright © 2012 John Wiley & Sons, Ltd.