More comprehensive 3D modeling of clay‐like material drying

Drying process plays an important role in the manufacturing of many products such as ceramic, kitchenware and building materials, some of which have complex three‐dimensional (3D) geometry. To deal with many restrictions found in literatures, a 3D numerical approach was used to describe the drying process of a porous Clay‐like material. The problem investigated involves highly coupled equations considering heat, mass, and mechanical aspects. The model is validated through the comparison of experimental measurements with simulation result. Simulation results show that increasing the initial moisture content and reducing the initial temperature have the same privilege and without significant increase in drying time, it reduces slightly the amount of maximum stress but delays the occurrence time of maximum stress. The nonuniform heat expansion induced stresses are very small in comparison to nonuniform moisture shrinkage induced stresses and can be neglected in drying simulation. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1469–1478, 2018     

A revised sales rebate contract with effort‐dependent demand: a channel coordination approach

In this paper, simultaneous coordination of order quantity and sales effort (SE) decisions in a supplier/retailer system with stochastic effort‐dependent demand is investigated. The main aim of the proposed model is to attain an optimal balance that results in a Pareto‐efficient solution for both channel members. A revised sales rebate (RSR) contract is developed to achieve channel coordination. In addition to the usual incentive approach of sales rebate schemes, a punitive approach is designed for the new proposed contract as a stockout penalty. Furthermore, some numerical experiments are examined to analyze the performance of the presented model under three decision‐making scenarios (i.e., decentralized, centralized, and RSR). Additionally, some in‐depth sensitivity analyses are conducted to examine the behavior of the supply chain performance under alteration of different parameters. The results show that the proposed RSR contract leads to channel coordination, while both channel members experience a Pareto improving situation. Moreover, it is proved that the RSR contract has significant potential on neutralizing adverse impacts of demand fluctuations on channel performance indicators.     

A representation of extra-special 2-group, entanglement, and Berry phase of two qubits in Yang-Baxter system

In this paper we show another representations of extra-special 2-groups. Based on this new representation, we infer a ${\mathbb{M}}$ matrix which obeys the extra-special 2-groups algebra relations. We also derive a unitary ${\breve{R}(\theta,\varphi)}$ matrix from the ${\mathbb{M}}$ using the Yang-Baxterization process. A Hamiltonian for the two qubits is constructed from the unitary ${\breve{R}(\theta,\varphi)}$ matrix. In this way, we study the Berry phase and entanglement of the two-qubit system. The results also establish relations between topological and holonomic quantum computation.     

E2EACK: an end-to-end acknowledgment-based scheme against collusion black hole and slander attacks in MANETs

Mobile ad hoc networks (MANETs) rely on the benevolence of nodes within the network to forward packets from a source node to a destination node. This network construction allows for the forwarding nodes, whether they are selfish or malicious, to drop packets hindering end-to-end communication. In this paper, a new scheme is proposed against collusion black hole and slander attacks in MANETs, named E2EACK. A novel method is used to detect collusion attacks due to collusive malicious nodes which cooperate in the route discovery, but refuse to forward data packets and do not disclose the misbehavior of each other. Contrary to existing methods that detect only collusion black hole attacks, the E2EACK also detects slander attacks and framing attacks. Moreover, the E2EACK uses ACKnowledgment packet to detect malicious nodes on the path and Message Authentication Code (MAC) to authenticate the sender of each data packet. Analytical and simulation results show that the proposed scheme considerably decreases the routing overhead and increases the packet delivery ratio compared to the existing methods.     

Study of the corrosion behavior of zinc and Zn–Co alloy electrodeposits obtained from alkaline bath using direct current

The corrosion behavior of Zn and Zn–Co alloy electrodeposits that were obtained from weakly alkaline glycine solutions has been studied. SEM, EDS and XRD were used to study surface morphology, chemical composition and phase structure of the coatings. Corrosion behavior of Zn and Zn–Co alloy coatings was studied by using potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. The results showed that increasing current density during deposition, increases cobalt content of the coating. It was also shown that increasing current density, up to 15 mA cm⁻², decreases the grain size and further increase in current density increases the grain size of the deposit. It was also noticed that corrosion resistance of deposits was highly influenced by the composition and morphology of the coatings. Zn–Co deposit containing 0.89 wt.% Co showed the highest corrosion resistance due to its single phase structure and its finer morphology.     

Evaluation on Properties of CaO-BaO-B2O3-Al2O3-SiO2 Glass-Ceramic Sealants for Intermediate Temperature Solid Oxide Fuel Cells

To develop suitable sealants for intermediate temperature solid oxide fuel cells (IT-SOFC), glasseceramics based on the CaO-BaO-B2O3-Al2O3-SiO2 system were studied. Coefficient of thermal expansion (CTE), glass transition temperature (Tg) and dilatometric softening point temperature (Td) of specimens were determined by means of dilatometer analysis and crystallization temperature was measured by differential thermal analysis (DTA). Also, crystallization behavior during prolonged heat-treatment and microstructure properties were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electrical properties were measured at different temperatures, and the results showed a high resistance (>10 4Ω) at the SOFC operation temperature (600-800℃). Moreover, mechanical properties of heat-treated specimens (1, 10, 30, 50 h) were measured. Microstructure investigation revealed a well-adhered bonding between the sealant glasseceramic electrolyte and glass.     

Lithium Perchlorate‐Catalyzed Boc Protection of Amines and Amine Derivatives

A new mild and chemoselective method for mono‐N‐protection of amines and amine derivatives as tert‐butoxycarbonyl derivatives is reported. The reaction proceeds with lithium perchlorate (20 mol %) and pyrocarbonates, and shows general applicability. The catalytic action of LiClO₄ is specific for the activation of Boc₂O, thus acid‐sensitive functionalities of the starting materials remain unchanged in the protection process. This procedure works well for sterically hindered primary amine as well as electron‐deficient primary arylamines, primary and secondary amino alcohols, α‐amino acid esters, hydroxylamines, hydrazines and sulfonamides.     

Design and analysis of an ultrawide-band distributed CMOS mixer

This paper presents the design and analysis of a novel distributed CMOS mixer for ultrawide-band (UWB) receivers. To achieve the UWB RF frequency range required for the UWB communications, the proposed mixer incorporates artificial inductance-capacitance (LC) delay lines in radio frequency (RF), local oscillator (LO), and intermediate frequency signal paths, and single-balanced mixer cells that are distributed along these LC circuits. Closed-form analytical model for the conversion gain of the mixer is presented. Furthermore, a comprehensive noise analysis of the proposed distributed mixer is carried out, which includes calculation of the mixer noise figure (NF) and derivation of the optimum number of stages, n, minimizing the NF. The designed mixer is capable of covering the RF and LO frequencies over a wide range of frequencies from 3.1-8.72 GHz. A two-stage distributed mixer has been fabricated in a 0.18-/spl mu/m CMOS process. Experiments show a conversion gain of more than 2.5 dB for the entire range of the frequencies. The dc power consumption is 10.4 mW.     

Designing a control mechanism using earned value analysis: an application to production environment

Earned value analysis is a project performance method which simultaneously presents both cost and schedule performances. The purpose of this paper is to model the uncertainty associated with activity duration in earned value analysis. The approach incorporates to design a control mechanism, which would be applicable through production control as well as project management problems. The job processing times have been considered as triangular fuzzy number. Costs are assumed to be directly related to fuzzy activity time, which are estimated through a bottom up hierarchy process. Consequently, different earned value metrics have been achieved. Research findings provide an efficient control mechanism in earned value analysis, which would be highly applicable in production control area. This research also yields a novel approach for representing a production performance index during implementation of production processes. In addition to the above mentioned issues, forecasting features can be further performed for predicting completion time of products for delivery to the customer. The approach presented in this paper has been successfully implemented through a multi-period–multi-product production planning problems, which efficiently demonstrates the applicability of the proposed control mechanism.     

Predictive field-oriented control of PMSM with space vector modulation technique

This paper is concerned with two popular and powerful methods in electrical drive applications: field-oriented control (FOC) and space vector modulation (SVM). The proposed FOC-SVM method is incorporated with a predictive current control (PCC)-based technique. The suggested method estimates the desirable electrical torque to track mechanical torque at a fixed speed operation of permanent magnet synchronous motor (PMSM). The estimated torque is used to calculate the reference current based on FOC. In order to improve the performance of the traditional SVM, a PCC method is established as a switching pattern modifier. Therefore, PCC-based SVM is employed to further minimize the torque ripples and transient response. The performance of the controller is evaluated in terms of torque and current ripple and transient response to step variations of the torque command. The proposed method has been verified with MATLAB-Simulink model. Simulation results confirm the ability of this technique in minimizing the torque and speed ripples and fixing switching frequency, simultaneously. However, it is sensitive to parameter changes.