A note on the application of the data envelopment analytic hierarchy process for supplier selection

In a very recent paper by Sevkli et al. (Sevkli, M., Koh, S.C.L., Zaim, S., Demirbag, M. and Tatoglu, E., 2007. An application of data envelopment analytic hierarchy process for supplier selection: a case study of BEKO in Turkey. International Journal of Production Research, 45 (9), 1973–2003), the data envelopment analytic hierarchy process (DEAHP) was claimed to outperform the analytic hierarchy process (AHP) method and provide a better decision for supplier selection. This note illustrates the weaknesses of the DEAHP, demonstrating the invalidity of the above claim. The case study of BEKO in Turkey is re-examined and shows that extra verification is needed to come to a decision.     

Importance of Volume Ratio in Photonic Effects of Lanthanide‐Doped LaPO4 Nanocrystals

Experimental variation of the volume ratio (filling factor: i.e., volume of nanoparticles (NPs) compared with that of medium) of nanocomposite materials with doped lanthanide ions demonstrates that it has a significant affect upon local field effects. Lanthanum orthophosphate NPs are doped with Eu³⁺ and/or Tb³⁺ and immersed in organic solvents and lead borate glasses for Tb^{3+ 5}D₄ lifetime measurements. For media with a refractive index (n_med) less than that of LaPO₄ (n_np = 1.79), the ⁵D₄ emission decay rate increases with increasing volume ratio of the NPs, whereas for n_med > 1.79, the decay rate decreases with increasing volume ratio. Fitting with the model of Pukhov provides an estimation of the radiative lifetime of ⁵D₄ and the quantum yield. Energy transfer (ET) from Tb³⁺ to Eu³⁺ occurs in co‐doped LaPO₄ NPs with excitation into a Tb³⁺ absorption band. The ET rate is independent on n_med and the energy transfer efficiency decreases with an increase in n_med. The behavior of ET rate with regard to the local field is consistent with the Dexter, but not Förster, equation for ET rate involving the electric dipole–electric dipole mechanism. This has consequences when using the spectroscopic ruler approach to measure distances between donor–acceptor chromophores.     

Recovery of heavy metals and stabilization of spent hydrotreating catalyst using a glass-ceramic matrix

Chemical analysis of spent Co/Mo/gamma Al(2)O(3) catalyst revealed the presence of carbon, molybdenum, sulfur, vanadium and cobalt at levels of 16.0, 10.9, 7.3, 4.6 and 4.0 wt.%, respectively. It was found that calcination at 500 degrees C provides an effective solution for the removal of carbon and sulfur and this generates the oxide form of the heavy metals. The removal of these heavy metals can be achieved through a two-stage leaching process. During the first stage, in which concentrated ammonia is used and it has been found that this process can be successful in removing as much as 83% (w/v) Mo. In a second stage, it was found that using 10% (v/v) of sulfuric acid, it was possible to account for up to 77% (w/v) Co and 4% (w/v) Mo removal. Leaching test results indicated that the vanadium present in the heated spent catalyst was almost stabilized but the molybdenum and cobalt were not. The combination of two solid wastes, ladle furnace slag (LFS) and treated residue of spent catalyst, could be used for making a high value-added anorthite glass-ceramic materials. Further leaching tests showed that ceramic glass materials provided a very effective method of Co, Mo and V heavy metals stabilization resulting in a product with a possible commercial value.     

Dynamic stiffness for piecewise non‐uniform Timoshenko column by power series—part II: Follower force

A follower force is an applied force whose direction changes according to the deformed shape during the course of deformation. The dynamic stiffness matrix of a non‐uniform Timoshenko column under follower force is formed by the power‐series method. The dynamic stiffness matrix is unsymmetrical due to the non‐conservative nature of the follower force. The frequency‐dependent mass matrix is still symmetrical and positive definite according to the extended Leung theorem. An arc length continuation method is introduced to find the influence of a concentrated follower force, distributed follower force, end mass and stiffness, slenderness, and taper ratio on the natural frequency and stability. It is found that the power‐series method can handle a very wide class of dynamic stiffness problem. Copyright © 2001 John Wiley & Sons, Ltd.     

对氡析出率测量的影响

采用局部静态法测量介质表面的氡析出率时 ,受表面同时析出 土气的影响 ,测量值可能偏高。由于土气子体 2 16Po的半衰期T1/2 =0 .1 5s,在设计氡析出率测量装置时 ,合理选择采样器高度可有效减小甚至克服 土气对氡析出率的测量影响。用采样截面为1 88mm、高 1 2 5mm、内加静电场 (由直流电源或驻极体产生 )的采样器 ,采样周期分别为 1、2和 3h ,被测介质表面 土气析出率比氡的高 2个数量级条件下 ,研究了氡析出率受 土气干扰的程度。理论计算结果表明 :采用CR 39固体核径迹探测器的驻极体多功能快速测氡仪和电源式多功能快速测氡仪测量氡析出率时 ,测量结果受 土气的干扰可能偏大 35 5 % ,而采用金硅面垒作探测器的PCMR 1连续测氡仪测量 ,氡析出率受 土气的干扰可忽略不计。     

Use of the Dielectric Resonator Antenna as a Filter Element

For the first time, the dielectric resonator antenna (DRA) is simultaneously used as a filtering device, named as the DRA filter (DRAF). The theory and design methodology of the DRAF are elucidated using the cylindrical DR. It was found that the operating frequency of the filter part can be made equal to, or different from, that of the antenna part. The return loss, input impedance, radiation patterns, and insertion loss of the DRAF are studied. To improve the insertion loss of the filter part, the DR is top-loaded by a metallic disk without significantly affecting the radiation efficiency of the antenna part. The disk, in addition, can be used to tune the frequency of the filter. It was found that the antenna and filter parts of the DRAF can be designed and tuned almost independently. A second-order DRAF is also designed in this paper. As the dual function DRAF is compact and cost effective, it should find applications in modern wireless communication systems.     

A Genetic-Algorithm-Based Optimization Model for Solving the Flexible Assembly Line Balancing Problem With Work Sharing and Workstation Revisiting

This paper investigates a flexible assembly line balancing (FALB) problem with work sharing and workstation revisiting. The mathematical model of the problem is presented, and its objective is to meet the desired cycle time of each order and minimize the total idle time of the assembly line. An optimization model is developed to tackle the addressed problem, which involves two parts. A bilevel genetic algorithm with multiparent crossover is proposed to determine the operation assignment to workstations and the task proportion of each shared operation being processed on different workstations. A heuristic operation routing rule is then presented to route the shared operation of each product to an appropriate workstation when it should be processed. Experiments based on industrial data are conducted to validate the proposed optimization model. The experimental results demonstrate the effectiveness of the proposed model to solve the FALB problem.     

Hybrid particle swarm optimization with wavelet mutation and its industrial applications.

A new hybrid particle swarm optimization (PSO) that incorporates a wavelet-theory-based mutation operation is proposed. It applies the wavelet theory to enhance the PSO in exploring the solution space more effectively for a better solution. A suite of benchmark test functions and three industrial applications (solving the load flow problems, modeling the development of fluid dispensing for electronic packaging, and designing a neural-network-based controller) are employed to evaluate the performance and the applicability of the proposed method. Experimental results empirically show that the proposed method significantly outperforms the existing methods in terms of convergence speed, solution quality, and solution stability.     

Cavity-backed slot-coupled dielectric resonator antenna excited bya narrow strip

The input impedance of the cavity-backed slot-coupled dielectric resonator antenna excited by a slender strip is investigated theoretically and experimentally. The effect of the cavity size and strip length on the input impedance are studied and discussed