Recognizing strong and weak congestion slack based in data envelopment analysis

The common concept of congestion is that a decrease (increase) in one or more inputs of a decision making unit (DMU) causes an increase (decrease) in one or more outputs (Cooper, Gu, & Li, 2001a). So far several congestion approaches have been proposed in DEA (data envelopment analysis) literature by many authors, such as Färe’s et al. (FGL), Brockett’s et al. (BCSW), and Tone and Sahoo’s congestion approaches (Färe et al., 1985, Färe et al., 1994, Brockett et al., 1998, Tone and Sahoo, 2004). Tone and Sahoo’s approach (Tone & Sahoo, 2004) is one of the most robust congestion approaches in DEA literature. Moreover, Tone and Sahoo’s approach has some advantages with respect to FGL and BSCW congestion approaches. However, the proposed approaches have many difficulties to treat congestion. For instance, in the presence of alternative optimal solutions, the approach proposed by Tone and Sahoo is unable to detect congestion (strong and weak). Moreover, in Tone and Sahoo’s approach, all inputs and outputs of decision making units (DMUs) have been considered positive, while in real world, data is often non-negative.In this research, a slack-based DEA approach is proposed to recognize congestion (strong and weak) for the target DMUs. One of the advantages of our proposed approach is capable of detecting congestion (strong and weak) for evaluating the DMUs in the presence of alternative optimal solutions. Other advantage of our research is capable of identifying congesting (strong and weak) DMUs with non-negative inputs and outputs. However in these situations, Tone and Sahoo’s congestion approach is incapable of identifying congestion. Lastly, we apply the approach to the data sets for making comparisons between the proposed approach and Tone and Sahoo’s approach then some conclusions are drawn and directions for future research are suggested.     

A biogeography-based optimization for optimum discrete design of skeletal structures

This article presents a modified biogeography-based optimization (MBBO) algorithm for optimum design of skeletal structures with discrete variables. The main idea of the biogeography-based optimization (BBO) algorithm is based on the science of biogeography, in which each habitat is a possible solution for the optimization problem in the search space. This algorithm consists of two main operators: migration and mutation. The migration operator helps the habitats to exploit the search space, while the mutation operator guides habitats to escape from the local optimum. To enhance the performance of the standard algorithm, some modifications are made and an MBBO algorithm is presented. The performance of the MBBO algorithm is evaluated by optimizing five benchmark design examples, and the obtained results are compared with other methods in the literature. The numerical results demonstrate that the MBBO algorithm is able to show very competitive results and has merits in finding optimum designs.     

采用数值建模对开裂剪切板进行屈曲分析

在民用、海洋和空间结构工程中采用剪切板是一种常见的做法,目前正在对带薄钢板剪力墙的剪切板的应用进行相关研究。一般剪切板的性能和设计程序大部分由其产生预屈服屈曲的情况而决定。然而,由于腐蚀、疲劳、焊接或操作不当而导致的裂纹缺陷,可能会使得剪切板产生承载力退化的情况,从而增加其分析的复杂性。基于有限元方法,对包含中央或边缘裂缝的剪切板提出建模和分析的方法,结果可达到分析裂纹尖端和边缘周围所必需的网格精度。此外,还分析了相对裂纹长度对屈曲承载能力的影响。     

Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked κC‐g‐AMPS superabsorbent hydrogel with antisalt and pH‐responsiveness properties

To synthesize a novel biopolymer‐based superabsorbent hydrogel, 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) was grafted onto kappa‐carrageenan (κC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′‐tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′‐methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for κC‐g‐AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature, were systematically optimized. The swelling measurements of the hydrogels were conducted in aqueous solutions of LiCl, NaCl, KCl, MgCl₂, CaCl₂, SrCl₂, BaCl₂, and AlCl₃. Due to the high swelling capacity in salt solutions, the hydrogels may be referred to as antisalt superabsorbents. The swelling of superabsorbing hydrogels was measured in solutions with pH ranging 1 to 13. The κC‐g‐AMPS hydrogel exhibited a pH‐responsiveness character so that a swelling–deswelling pulsatile behavior was recorded at pH 2 and 8. The overall activation energy for the graft copolymerization reaction was found to be 14.6 kJ/mol. The swelling kinetics of the hydrogels was preliminarily investigated as well. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 255–263, 2005     

Design assessment of a multiple passenger vehicle component using load transfer index ($$ {\text{U}}^{*} $$) method

In recent years, the study of the load transfer in the structure has achieved a growing attention from mechanical engineers, specifically in the vehicle industry. To further develop this relatively new branch of structural analysis and in particular the \( {\text{U}}^{*} \) index theory for load transfer analysis, it seems necessary to apply this method to different vehicle components. Therefore, in this study, one of the main load carrying components of a multiple passengers carrying vehicle was chosen for load transfer analysis. This choice has significant importance due to the focus of previous \( {\text{U}}^{*} \) index studies on small passenger vehicles, which have completely different structure and load paths. Another important feature of this study is the application of a sophisticated and detailed approach for choosing the loading and boundary condition. To address an actual working condition, a full model of the vehicle was analyzed under different working loads and the most severe loading condition was selected for this study. Then, a detailed \( {\text{U}}^{*} \) index analysis was performed on the structure to evaluate the load transfer for both loading and reaction forces. Based on the results of this analysis, parts with questionable stiffness were located and a design modification was proposed to improve the structural behavior. In addition, to verify the computer model and conclusions of the \( {\text{U}}^{*} \) index analysis, the structure was tested physically under same loading condition. Finally, the proposed modified design of the structure was analyzed with \( {\text{U}}^{*} \) index theory, and using the design criteria suggested in the theory, it was shown that the new design has great potential for better performance and more efficient load transfer.     

Electrophoretic deposition of Sn-doped TiO<Subscript>2</Subscript> nanoparticles and its optical and photocatalytic properties

In this research, Sn-doped TiO₂ (Sn–TiO₂) nanoparticles were synthesized by a simple sol–gel method. The structure and composition of the as-prepared sample were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible absorption spectroscopy. Electrophoretic deposition (EPD) technique was used to deposit thin films of Sn–TiO₂ on 316L stainless steel (316L SS) substrate. In order to achieve a fine and high-quality layer on the electrode surface, N-phenyl-p-phenylenediamine (NPPDA) was used as a new dispersant and charging agent in ethanolic suspensions. Based on zeta potential and conductivity measurements of the suspensions, an optimum concentration of the NPPDA dispersant was found to be 3.0 g l^?1. The in-situ EPD kinetics was also studied. The prepared Sn–TiO₂ film was used for the photodegradation of methylene blue (MB) under UV, visible and sun lights. The results revealed that the Sn–TiO₂ film could be able to degrade the MB under sunlight. The calculated degradations were 44, 65, and 73% after 2, 4 and 5 h, respectively. The relation between \(\ln \left( {\frac{{{{\text{A}}_0}}}{{\text{A}}}} \right)\) and time was linear, so it was proved that the photocatalytic degradation of MB can be characterized by pseudo-first order reaction kinetics.     

A Priority-Based MAC Protocol for Energy Consumption and Delay Guaranteed in Wireless Body Area Networks

Wireless Personal Communications - Wireless body area networks (WBANs) consist of tiny sensors that placed around or implant in the human body. These nodes can permanently monitor the health of...     

An Online Cost-Based Job Scheduling Method by Cellular Automata in Cloud Computing Environment

Wireless Personal Communications - Cloud computing has expanded considerably in industry and research and is based on a pay-as-you-go payment model. In cloud computing environment, on one hand,...     

High speed residue number system comparison for the moduli set {2^n-1, 2^n, 2^n＋}

The Residue Number System （RNS） exploits advantages of fast computing, parallelism and fault tolerant because of its carry-free property in operations. This essential property gives RNS this ability to eliminate the problem of carry propagations in calculations and provides high-speed computing consequently. In RNS some operations like addition and multiplication can be done in parallel, faster and with less complexity than conventional numeric systems so it is used in many applications like Digital Signal Processing （DSP）, Cryptography and Image Processing. Normally these applications require comparison in their operations. Comparison is a fundamental operation in numeric systems. On the other hand, the noticed property makes comparison difficult and complex in RNS. The pervious methods or algorithms for RNS comparison used redundant moduli set, ROM look-up tables or implemented complete RNS to binary（R/B） convert. We propose a new RNS comparison technique, which performs RNS comparison without using a redundant module and complete converting from RNS to binary system. Our technique implements RNS comparison much faster applying a few more hardware than previous techniques.