A proposed approach for setup time reduction through integrating conventional SMED method with multiple criteria decision-making techniques

Short setup time is an essential element for the effective implementation of many lean pillars, i.e., JIT, and Kanban. Most of the current setup reduction methodologies are based on Shingo’s Single Minute Exchange of Dies (SMED) that suggests the conversion of internal setup operations to external operations. However, the conventional SMED approach – as proposed by Shingo – does not possess a systematic approach to accomplish this conversion. Thus, a new approach is proposed in order to aid the process engineers in implementing SMED. The proposed approach is based on the conventional SMED, but also it incorporates Multiple Criteria Decision-Making Techniques (MCDM) to the third implementation phase. The MCDM techniques used in this work are Analytical Hierarchal Process (AHP), Preference Selection Index (PSI) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The proposed approach provides a systematic procedure for selecting the best setup technique among the available alternatives, and takes also into consideration other factors that affect the decision-making process; including: cost, energy, facility layout, safety, life, quality and maintenance. A real example of PVC industry is used to exemplify the approach. The results demonstrate the capability of the proposed approach in setup time reduction, which in turn will improve machines’ utilization, and increase the productivity and flexibility of the whole facility.     

Multi-criteria expertness based cooperative Q-learning

One of the most influential points in cooperative learning is the type of exchanging information. If the content of exchanging information among agents is rich, cooperation gives rise to better results. To extract proper knowledge of agents during the cooperation process, some expertness measures that assign expertness levels to the other agents are used. In this paper, a new method named Multi-Criteria Expertness based cooperative Q-learning (MCE) is proposed that utilizes all of the expertness measures and attempts to enrich the exchanging information more efficiently. In MCE, all expertness measures are considered simultaneously and collective knowledge is equal to the combination of learned knowledge by each of expertness measures. The experimental results confirm outstanding performance of the proposed method on a sample maze world and a hunter-prey problem.     

A group theoretic approach to construct cryptographically strong substitution boxes

In this paper, we present a method to construct a substitution box used in encryption applications. The proposed algorithm for the construction of substitution box relies on the linear fractional transform method. The design methodology is simple, while the confusion-creating ability of the new substitution box is complex. The strength of the proposed substitution box is evaluated, and an insight is provided to quantify the confusion-creating ability. In addition, tests are performed to assess the vulnerability of the encrypted data to algebraic and statistical attacks. The substitution box is critically analyzed by strict avalanche criterion, bit independent criterion, differential approximation probability test, linear approximation probability test, non-linearity test, and majority logic criterion. The performance of the proposed substitution box is also compared with those of some of the well-known counterparts including AES, APA, Gray, S₈, Skipjack, Xyi, and prime of residue substitution boxes. It is apparent that the performance, in terms of confusion-creating ability, of the new substitution box is better than those of some of the existing non-linear components used in encryption systems. The majority logic criterion is applied to these substitution boxes to further evaluate the strength and usefulness.     

Optimal design of laser solid freeform fabrication system and real-time prediction of melt pool geometry using intelligent evolutionary algorithms

With the rapid growth of laser applications and the introduction of high efficiency lasers (e.g. fiber lasers), laser material processing has gained increasing importance in a variety of industries. Among the applications of laser technology, laser cladding has received significant attention due to its high potential for material processing such as metallic coating, high value component repair, prototyping, and even low-volume manufacturing. In this paper, two optimization methods have been applied to obtain optimal operating parameters of Laser Solid Freeform Fabrication Process (LSFF) as a real world engineering problem. First, Particle Swarm Optimization (PSO) algorithm was implemented for real-time prediction of melt pool geometry. Then, a hybrid evolutionary algorithm called Self-organizing Pareto based Evolutionary Algorithm (SOPEA) was proposed to find the optimal process parameters. For further assurance on the performance of the proposed optimization technique, it was compared to some well-known vector optimization algorithms such as Non-dominated Sorting Genetic Algorithm (NSGA-II) and Strength Pareto Evolutionary Algorithm (SPEA 2). Thereafter, it was applied for simultaneous optimization of clad height and melt pool depth in LSFF process. Since there is no exact mathematical model for the clad height (deposited layer thickness) and the melt pool depth, the authors developed two Adaptive Neuro-Fuzzy Inference Systems (ANFIS) to estimate these two process parameters. Optimization procedure being done, the archived non-dominated solutions were surveyed to find the appropriate ranges of process parameters with acceptable dilutions. Finally, the selected optimal ranges were used to find a case with the minimum rapid prototyping time. The results indicate the acceptable potential of evolutionary strategies for controlling and optimization of LSFF process as a complicated engineering problem.     

Production of in situ aluminum-titanium diboride master alloy formed by slag-metal reaction

Al-TiB₂ master alloys have received much attention in recent years owing to their potential as efficient grain refiners for aluminum foundry alloys. In this study, the process of production of master alloys was investigated to develop a low cost method, namely, slag-metal reaction. This method can be used to fabricate Al-TiB₂ master alloy in situ from the TiO₂-H₃BO₃-Na₃AlF₆ and Al system. Since the price of the raw materials is low and the technology is simple, the processing technique appears to reduce the cost of the master alloy. Because of exothermic reactions, not much energy is needed to melt materials. In this process, Titanium diboride particles were formed in situ through the reactions of TiO₂, H₃BO₃ and Na₃AlF₆. Results showed that when the aluminum melted, the condensed TiB₂ particles that formed in situ were spherical with an average diameter of 1 μm. Furthermore, these TiB₂ particles were distributed uniformly through the master alloy.     

Investigation of structural and optoelectronic properties of BaThO3

Structural and optoelectronic properties of BaThO₃ cubic perovskite are calculated using all electrons full potential linearized augmented plane wave (FP-LAPW) method. Wide and direct band gap, 5.7 eV, of the compound predicts that it can be effectively used in UV based optoelectronic devices. Different characteristic peaks in the wide UV range emerges mainly due to the transition of electrons between valance band state O-p and conduction band states Ba-d, Ba-f, Th-f and Th-d.     

64抽头LED线性亮度控制器用数字电位计控制LED亮度

采用LED但缺少微控制器或其它形式控制功能的应用可以得益于一种简单的电路,该电路能对LED的光强作手动控制.适合这种目的的器件有机械式(模拟)和电子式(数字)电位器.     

Synthesis,characterization, and supercapacitor studies of manganese (IV) oxide nanowires

One-dimensional manganese (IV) oxide (MnO₂) (～20 nm in average diameter) were synthesized by cathodic electrodeposition and heat treatment. The mechanism of electrodeposition and nanowire formation were discussed. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR). Nanowires with varying lengths and diameters were found in TEM and SEM images of the sample. The results of N₂ adsorption–desorption analysis indicated that the BET surface area of the MnO₂ nanowires was 157 m² g^?1 and the pore size distributions were 2.5 and 4.5 nm. The electrochemical performances of the prepared MnO₂ as an electrode material for supercapacitors were evaluated by cyclic voltammetry and galvanostatic charge/discharge measurements in a solution of 0.5 M Na₂SO₄. The higher specific capacitance of 318 F g^?1 and good capacity retention of 86% were achieved after 1000 charge–discharge cycles had been observed for the MnO₂ nanowires electrode.     

A secure search protocol for lightweight and low-cost RFID systems

In radio frequency identification (RFID) systems, search protocols are used to find a specific item in a large number of tagged products. These protocols should be secure against RFID attacks such as traceability, impersonation, DoS and eavesdropping. Sundaresan et al. (IEEE Trans Dependable Secure Comput, 2015) presented a server-less search protocol based on 128-bits PRNG function and claimed that their method can address all vulnerabilities of previous protocols. In this paper, we prove that Sundaresan et al.’s protocol is vulnerable to traceability attack with the high probability. In addition, we present an improved protocol to solve the proposed problem and analyze its security level informally and formally based on AVISPA tool and BAN logic.