A new two-stage Stackelberg fuzzy data envelopment analysis model

Data Envelopment Analysis (DEA) is a widely used mathematical programming approach for evaluating the relative efficiency of Decision Making Units (DMUs). Conventional DEA methods treat DMUs as “black boxes”, focusing entirely on their relative efficiencies. We propose an efficient two-stage fuzzy DEA model to calculate the efficiency scores for a DMU and its sub-DMUs. We use the Stackelberg (leader–follower) game theory approach to prioritize and sequentially decompose the efficiency score of the DMU into a set of efficiency scores for its sub-DMUs. The proposed models are linear and independent of the α-cut variables. The linear feature allows for a quick identification of the global optimum solution and the α-cut independency feature allows for a significant reduction in the computational efforts. Monte Carlo simulation is used to discriminately rank the efficiencies in the proposed method. We also present a case study to exhibit the efficacy of the procedures and to demonstrate the applicability of the proposed method to a two-stage performance evaluation problem in the banking industry.     

Developing distinctive two-stage data envelopment analysis models: An application in evaluating the sustainability of supply chain management

Sustainable supply chain management (SSCM) has received much attention from scholars and practitioners in the past years. It has become a method for simultaneous improvement of economic, social, and environmental performance. SSCM evaluation, therefore, is a significant duty for any types of organizations. Among evaluation methods, data envelopment analysis (DEA) seems to be an appropriate technique for assessment of the SSCM. One of the uses of DEA is to evaluate the efficiency of two-stage processes, where all the outputs from the first stage are intermediate measures that are considered as the inputs to the second stage. The resulting two-stage DEA models assess both the overall efficiency score of the whole process and each of the individual stages. Notwithstanding, there are major weaknesses in the previous extensions of two-stage DEA models. Firstly, a challenging issue is that suggestions for improvements are offered only for input and output measures, and intermediate measures are neglected. Although, some extensions for network structures take into account intermediate measures, they arbitrarily assign an input or output role for the measures, thus in optimal solution for inefficient DMUs, this measures are forced to respectively take a lower or upper amount. Secondly, the efficiency scores are calculated based on inputs and outputs. That is, while the models consider these measures by corresponding constraints, the intermediate measures are not included in the objective function, or incorrectly assign an input or output role. Thirdly, in some cases, the former developments specify points on the efficient frontier only for inefficient stages, while for a network which is entirely inefficient such points are also required. Moreover, the organization (which in DEA terminology is named decision making unit) is supposed to be divided into two autonomous departments. It means that the performance of one department is quite unrelated to another department, while from the organizational perspective this is called into the question. To overcome these shortcomings, in this paper, innovative models are proposed. The proposed ideas are used for evaluating the sustainability of supply chains in resin producing companies.     

谐波齿轮传动中柔轮载荷分布规律分析研究

提出了关于谐波齿轮传动装置中,柔轮啮合区内载荷分布规律的实验与分析新方法。包括三部分：首先,在载荷状态下,通过安装在刚轮径向方向上三个可装、的活齿,测得大量的啮合数据;其次,通过数学统计方法获得啮合区内切向力Ft和径向力Fr的实验曲线;最后,应用函数逼近法获得载荷区内载荷分布方程。     

Sustainable cultivation location optimization of the Jatropha curcas L. under uncertainty: A unified fuzzy data envelopment analysis approach

Second-generation biodiesel production from non-edible high oil content feedstocks such as Jutropha curcas L. (JCL) has been found as a suitable alternative for the fossil diesel which is mostly consumed in transportation sector. Second-generation biodiesel eliminates the drawbacks of the first generation such as food-energy challenge and provides opportunity for rural development. Location optimization of JCL plays a vital role in the success and prosperity of JCL projects. In this study, sustainability and ecological indicators are defined to evaluate the performance and efficiency of the candidate locations for JCL cultivation under uncertainty. The values of defined indicators are highly tainted with uncertainty in real-life situation. To optimize the candidate locations for JCL cultivation under uncertainty, an efficient Unified Fuzzy Data Envelopment Analysis (UFDEA) model is developed. The proposed UFDEA model is verified and validated through investigating a real case study in Iran and the associated results are compared to those obtained by the crisp Unified Data Envelopment Analysis model under different levels of uncertainty. The obtained results show the applicability of the proposed UFDEA model in selecting suitable areas for JCL cultivation under uncertainty.     

空间相机镜筒柔性支撑结构设计与动力学分析

为了减小卫星平台的随机振动对空间相机像质的影响,为空间相机的镜筒设计了一套柔性支撑结构,并对柔性结构的动力学特性进行了深入研究.首先,在镜筒及其支座之间放置2mm厚的橡胶环,使镜筒和支撑之间形成柔性连接.然后,应用参数识别的方法对柔性支撑的迟滞阻尼特性进行分析,得到其刚度系数和阻尼系数随频率变化的公式.最后,使用拉格朗日法建立整个系统的动力学方程,得到镜筒质心位置位移和转角随频率变化的曲线.动力学分析结果表明:当振动频率大于663Hz时,位移传递率小于0.6;当频率大于974Hz时,转角变化范围在(0.046±0.050)°之间;满足设计要求.柔性支撑结构对高频振动抑制效果显著,可以为空间相机提供一个稳定的工作环境.     

A dynamic heuristic-based algorithm to part input sequencing in flexible manufacturing systems for mass customization capability

In the increasingly competitive global markets, enterprises face challenges in responding to customer orders quickly, as well as producing customized products cost-effectively. This paper proposes a dynamic heuristic-based algorithm for the part input sequencing problem of flexible manufacturing systems (FMSs) in a mass customization (MC) environment. The FMS manufactures a variety of parts, and customer orders arrive dynamically with order size as small as one. Segmental set functions are established in the proposed algorithm to apply the strategy of dynamic workload balancing, and the shortest processing time (SPT) scheduling rule. Theoretical analysis is performed and the effectiveness of the algorithm in dynamic workload balancing under the complex and dynamic environment is proven. The application of the algorithm is illustrated by an example. The potential of its practical applications to the FMSs in make-to-order (MTO) supply chains is also discussed. Further research is provided.

Intra-session reliability of traditional and nonlinear time-series posturographic measures in a semi-tandem stance: A reference to age

The purpose of this study was to evaluate the intra-session reliability of traditional and nonlinear time-series center of pressure (CoP) based measures of postural sway during upright semi-tandem quiet stance in young vs. older subjects. Seventy-four healthy volunteers (40 young individuals, mean age: 27 ± 6 yrs; 34 older individuals, mean age: 79 ± 8 yrs) performed three 30-s trials of semi-tandem quiet stance on a force plate with their eyes open. Traditional posturography analysis and 4 nonlinear time-series analyses (sway density plots, diffusion plots, recurrence quantification, sample entropy analyses) were applied to the recorded CoP time series, based on which 13 traditional and 32 nonlinear time-series CoP-based measures were calculated. Significant trial-to-trial improvements (particularly between the first and second trial) were observed in the calculated CoP measures in only 2 and 4 cases in the young and older individuals respectively. Regarding the traditional CoP measures, the highest intraclass correlation coefficients (ICC_average, i.e. ICC_2,k) (0.75–0.96) and the lowest coefficients of variation (CV) (8.2–27.3%) in both age groups were observed in the mean frequency of CoP local extrema, the mean amplitude of CoP excursion, and the time-normalized CoP area, although for some of the measures we recommend an additional familiarization trial due to systematic bias. Regarding the structural mechanics CoP measures, the highest ICCa (0.70–0.94) and the lowest CVs (1.2–8.4%) in both age groups were observed in those derived from recurrence quantification and sample entropy analyses, respectively. These CoP measures could be recommended for further use in basic and clinical studies, particularly those on age-related changes in postural control during the semi-tandem quiet stance.     

A method for spatio-temporal (4-D) data representation in confocal microscopy: application to neuroanatomical plasticity

This paper describes a new method for data representation and visualization in four dimensions (three dimensions plus time). Sequential volumes, exhibiting morphological activity, are acquired non-invasively with a confocal scanning laser microscope, where each data set corresponds to a time sample. A pipelined processing includes packing of volumes and specific volume rendering techniques. Subsequent processing in HIS (hue, intensity, saturation) colour space combines functional, packed images with shaded three-dimensional views. As a result, even subtle changes in morphology become visible and computational time is saved. Experimental findings obtained from investigations of synaptic plasticity in cultured retinal tissue are reported.     

A study on the fault diagnosis of roller-shape using frequency analysis of tension signals and artificial neural networks based approach in a web transport system

Rollers in the continuous process systems are ones of key components that determine the quality of web products. The condition of rollers (e.g. eccentricity, runout) should be consistently monitored in order to maintain the process conditions (e.g. tension, edge position) within a required specification. In this paper, a new diagnosis algorithm is suggested to detect the defective rollers based on the frequency analysis of web tension signals. The kernel of this technique is to use the characteristic features (RMS, Peak value, Power spectral density) of tension signals which allow the identification of the faulty rollers and the diagnosis of the degree of fault in the rollers. The characteristic features could be used to train an artificial neural network which could classify roller conditions into three groups (normal, warning, and faulty conditions). The simulation and experimental results showed that the suggested diagnosis algorithm can be successfully used to identify the defective rollers as well as to diagnose the degree of the defect of those rollers.     

Processing of X-ray tomographic images: A procedure adapted for the analysis of phase distribution in MellapakPlus 752.Y and Katapak-SP packings

We developed a practical methodology to face common problems encountered in the analysis of tomographic images to get quantitative information on phase distributions in gas liquid contacting columns packed with complex metallic packings. In the present study, the procedure was developed and validated for MellapakPlus 752.Y and Katapak-SP packings, but it may be applied to any type of metallic or modular packing of similar dimensions. Steps of tomographic image processing and associated parameters (threshold, calibration factors for solid and liquid phase) were first determined on images of dry and flooded packing elements of MellapakPlus 752.Y. The parameter values were then adapted to analyse images of dry and flooded packing elements of Katapak-SP, which are made of an alternation of MellapakPlus 752.Y sheets and catalytic baskets. In a certain way, MellapakPlus 752.Y and Katapak-SP (11 and 12), the global geometrical properties of which are well known, are used as physical phantoms to develop a validated image post-processing procedure.The latter is used to quantitatively analyse liquid distribution images in irrigated MellapakPlus 752.Y and Katapak-SP (11 and 12) packings, giving access to spatial distribution of local values of hydrodynamic quantities such as the liquid holdup and gas-liquid interfacial area. Global values of the liquid hold-up, relative to the whole packed bed volume are determined by averaging tomographic results over the column height. They are successfully compared with bed scale data measured on the same MellapakPlus 752.Y and Katapak-SP (11 and 12). This analysis further validates the procedure used for the processing of tomographic irrigated images.So the proposed methodology enables one to obtain quantitative information on the spatial distributions of structural quantities as well as of hydrodynamic quantities in complex metallic packings, which are fully validated on the basis of a comparison with global values obtained by well-established measurement techniques.     

A numerical analysis on the curved bileaflet mechanical heart valve (mhv): leaflet motion and blood flow in an elastic blood vessel

In blood flow passing through the mechanical heart valve (MHV) and elastic blood vessel, hemolysis and platelet activation causing thrombus formation can be seen owing to the shear stress in the blood. Also, fracture and deformation of leaflets can be observed depending on the shape and material properties of the leaflets which is opened and closed in a cycle. Hence, comprehensive study is needed on the hemodynamics which is associated with the motion of leaflet and elastic blood vessel in terms of fluid-structure interaction. In this paper, a numerical analysis has been performed for a three-dimensional pulsatile blood flow associated with the elastic blood vessel and curved bileaflet for multiple cycles in light of fluid-structure interaction. From this analysis fluttering phenomenon and rebound of the leaflet have been observed and recirculation and regurgitation have been found in the flow fields of the blood. Also, the pressure distribution and the radial displacement of the elastic blood vessel have been obtained. The motion of the leaflet and flow fields of the blood have shown similar tendency compared with the previous experiments carried out in other studies. The present study can contribute to the design methodology for the curved bileaflet mechanical heart valve. Furthermore, the proposed fluid-structure interaction method will be effectively used in various fields where the interaction between fluid flow and structure are involved.