Location and transportation planning in supply chains under uncertainty and congestion by using an improved electromagnetism-like algorithm

Supply chain decision makers are constantly trying to improve the customer demand fulfillment process and reduce the associated costs via decision making models and techniques. As two of the most important parameters in a supply chain, supply and demand quantities are subject to uncertainty in many real-world situations. In addition, in recent decades, there is a trend to think of the impacts of supply chain design and strategies on society and environment. Especially, transportation of goods not only imposes costs to businesses but also has socioeconomic influences. In this paper, a fuzzy nonlinear programming model for supply chain design and planning under supply/demand uncertainty and traffic congestion is proposed and a hybrid meta-heuristic algorithm, based on electromagnetism-like algorithm and simulated annealing concepts, is designed to solve the model. The merit of this paper is presenting a realistic model of current issues in supply chain design and an efficient solution method to the problem. These are significant findings of this research which can be interesting to both researchers and practitioners. Several numerical examples are provided to justify the model and the proposed solution approach.     

Visual domain adaptation via transfer feature learning

One of the serious challenges in computer vision and image classification is learning an accurate classifier for a new unlabeled image dataset, considering that there is no available labeled training data. Transfer learning and domain adaptation are two outstanding solutions that tackle this challenge by employing available datasets, even with significant difference in distribution and properties, and transfer the knowledge from a related domain to the target domain. The main difference between these two solutions is their primary assumption about change in marginal and conditional distributions where transfer learning emphasizes on problems with same marginal distribution and different conditional distribution, and domain adaptation deals with opposite conditions. Most prior works have exploited these two learning strategies separately for domain shift problem where training and test sets are drawn from different distributions. In this paper, we exploit joint transfer learning and domain adaptation to cope with domain shift problem in which the distribution difference is significantly large, particularly vision datasets. We therefore put forward a novel transfer learning and domain adaptation approach, referred to as visual domain adaptation (VDA). Specifically, VDA reduces the joint marginal and conditional distributions across domains in an unsupervised manner where no label is available in test set. Moreover, VDA constructs condensed domain invariant clusters in the embedding representation to separate various classes alongside the domain transfer. In this work, we employ pseudo target labels refinement to iteratively converge to final solution. Employing an iterative procedure along with a novel optimization problem creates a robust and effective representation for adaptation across domains. Extensive experiments on 16 real vision datasets with different difficulties verify that VDA can significantly outperform state-of-the-art methods in image classification problem.     

Highly Linear High-Frequency Low-Noise Amplifier Design at ISM Band

A highly linear high-frequency low-noise amplifier is one of the important components in telecommunication receivers. The purpose of making such amplifiers is to amplify received signal from transmitter (antenna) at an acceptable level. A narrow band highly linear low-noise amplifier was studied and designed in this paper. A BFP720 bipolar transistor from Infineon Company associated with ADS software was used. Low-noise amplifier was initially designed and simulated and its results were obtained. Lumped elements of inductor and capacitor were used in the design of input and output matching network of this circuit, and two amplifier circuits were then designed and some techniques and methods proposed to improve its performance.

     

Effect of cross‐linking time on the thermal and mechanical properties and pervaporation performance of poly(vinyl alcohol) membrane cross‐linked with fumaric acid used for dehydration of isopropanol

Cross‐linked poly (vinyl alcohol) membranes were prepared using fumaric acid as the cross‐linking agent and were used for the pervaporation separation of water/isopropanol mixtures. Cross‐linking process was carried out at 150°C at three different times of 10, 30, and 60 min. The membranes were characterized by different known methods of FT‐IR, TGA, XRD as well as tensile test. The effects of cross‐linking time on the thermal and mechanical properties of the membranes and also their pervaporation performance were investigated. Formation of more ester groups by increasing the cross‐linking time was confirmed by the FT‐IR results. TGA analyses showed that thermal stability of the membranes is improved by prolonging the duration of cross‐linking process. This was due to the formation of more compact structure in the membranes. The XRD results revealed that the crystalline regions of the membranes were relatively diminished with an increase in the cross‐linking time. No specific trend was observed for the variation of tensile strength at break with the cross‐linking time. The PVA membrane cross‐linked for 60 min showed high selectivity of 1492 for water permeation for the feed mixture containing 10 wt % water. The temperature dependency of the permeation flux was investigated using Arrhenius relationship, and the activation energy values were calculated for total permeation (E_p), water (E_pw), and IPA (E_pIPA) fluxes. Lower value of E_pw in comparison with E_pIPA supported excellent dehydration performance of the cross‐linked membranes. Despite large increase in activation energy of water with prolonged cross‐linking time, the selectivity was improved. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2013     

A low-power, second-order Δ/Σ modulator using a single class-AB op-amp for voice-band applications

The design of a power-efficient second-order Δ/Σ modulator for voice-band is presented. At system level, a new single-loop, single-stage modulator is proposed. The modulator employs only one class-AB op-amp to realize a second-order noise shaping for voice-band applications. The modulator is designed in a 0.25μm standard CMOS process, and exhibits 86 dB dynamic range (DR) for a 4 kHz voice-bandwidth. The proposed modulator consumes 125μW from a 2.5 V supply. Aminghasem Safarian received the B.S. and M.S. degrees in electrical engineering from the Sharif University of Technology, in 2000, 2002, respectively. Since 2003 he is a research assistant at University of California, Irvine, working toward his Ph.D. degree in electrical engineering emphasizing on RF IC design for wireless communication systems. During the summer of 2005, he was with Broadcom Corporation, Irvine, CA, where he developed integrated receivers for RFID and WCDMA applications. Farzad Sahandiesfanjani was born in Tabriz, Iran in 1976. He received the B.S. and M.S. degrees in electronics from Sharif University of Technology, Tehran, Iran, in 1998 and 2000, respectively. The subject of his thesis was the design of 4th order cascade delta-sigma modulator for ADSL Analog Front End. From 1998 to 2003, he was with Emad Semicon Co., Tehran, Iran, where he designed circuits for voice application such as CODEC and SLIC chip. He also designed a 3rd order single loop class-D delta-sigma modulator for audio application. He joined Tripath Technology Inc., San Jose, CA, in 2003 and has been working on the design of analog and mixed-signal circuits for class-T audio power amplifier. He is also author of one patent for inductor-less switching audio power amplifier and also co-author of 3 more pending patents and 4 papers. Payam Heydari (S'98–M'00) received the B.S. and M.S. degrees (with honors) in electrical engineering from the Sharif University of Technology, in 1992, 1995, respectively. He received the Ph.D. degree in electrical engineering from the University of Southern California, in 2001. During the summer of 1997, he was with Bell-Labs, Lucent Technologies, Murray Hill, NJ, where he worked on noise analysis in deep submicron very large-scale integrated (VLSI) circuits. During the summer of 1998, he was with IBM T. J. Watson Research Center, Yorktown Heights, NY, where he worked on gradient-based optimization and sensitivity analysis of custom-integrated circuits. Since August 2001, he has been an Assistant Professor of Electrical Engineering at the University of California, Irvine, where his research interest is the design of high-speed analog, radio-frequency (RF), and mixed-signal integrated circuits. Dr. Heydari has received the 2005 National Science Foundation (NSF) CAREER Award, the 2005 IEEE Circuits and Systems Society Darlington Award, the 2005 Henry Samueli School of Engineering Teaching Excellence Award, the Best Paper Award at the 2000 IEEE International Conference on Computer Design (ICCD), the 2000 Honorable Award from the Department of EE-Systems at the University of Southern California, and the 2001 Technical Excellence Award in the area of Electrical Engineering from the Association of Professors and Scholars of Iranian Heritage (APSIH). He was recognized as the 2004 Outstanding Faculty at the EECS Department of the University of California, Irvine. His name was included in the 2006 Who's Who in America. Dr. Heydari is an Associate Editor of the IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—part I. He currently serves on the Technical Program Committees of Custom Integrated Circuits Conference (CICC), International Symposium on Low-Power Electronics and Design (ISLPED), International Symposium on Quality Electronic Design (ISQED), and the Local Arrangement Chair of the ISLPED conference. He was the Student Design Contest Judge for the DAC/ISSCC Design Contest Award in 2003, the Technical Program Committee member of the IEEE Design and Test in Europe (DATE) from 2003 to 2004, and International Symposium on Physical Design (ISPD) in 2003. Mojtaba Atarodi received his Ph.D degree from USC (the University of Southern California, Los Angeles), in electrical engineering Electro-physics in 1993, his M.S from University of California at Irvine, and his B.SEE from the Tehran Polytechnic University with first Grade honor. Following his Ph.D completion, he was with Linear Technology Corporation from 1993 to 1996 as an analog design engineer. He has been with Sharif University of Technology as an Assistant and Visiting Professor since 1997. The Author of more than 50 technical journal and conference papers an a book on Analog CMOS IC Design, Dr Atarodi’s main research interests are analog and RF IC system, circuit, and signal processing design as well as analog synthesis tools. Having held several management and consulting positions during the last 15 years in the US industry, he holds one US patent in analog highly linear tunable Operational Transconductance Amplifiers and has applied for 5 more US patents as well.     

A new quasi-resonant DC-link PWM inverter using single switch for soft switching

This paper presents a new quasi-resonant DC-link (QRDCL) inverter. Only one switching device is used to create zero voltage instants under all load conditions. The maximum voltage across the inverter devices is maintained at around (1.01-1.1) times the input source voltage. The circuit has the flexibility of selecting switching instants of the resonant link in synchronism with any PWM technique. Control technique does not require the help of inverter switches to create the zero voltage instants in the DC-link, and voltage and current sensors are eliminated from the control circuit. In this paper, the principle of operation and detailed analysis of the proposed QRDCL inverter are presented and design considerations for achieving soft switching are obtained. Detailed PSPICE simulation studies are carried out to study the feasibility of the proposed topology under various load conditions. The experimental results of the proposed QRDCL PWM inverter feeding a three phase induction motor are given.     

Transmitter optimization and optimality of beamforming for multiple antenna systems

We solve the transmitter optimization problem and determine a necessary and sufficient condition under which beamforming achieves Shannon capacity in a linear narrowband point-to-point communication system employing multiple transmit and receive antennas with additive Gaussian noise. We assume that the receiver has perfect channel knowledge while the transmitter has only knowledge of either the mean or the covariance of the channel coefficients. The channel is modeled at the transmitter as a matrix of complex jointly Gaussian random variables with either a zero mean and a known covariance matrix (covariance information), or a nonzero mean and a white covariance matrix (mean information). For both cases, we develop a necessary and sufficient condition for when the Shannon capacity is achieved through beamforming; i.e., the channel can be treated like a scalar channel and one-dimensional codes can be used to achieve capacity. We also provide a waterpouring interpretation of our results and find that less channel uncertainty not only increases the system capacity but may also allow this higher capacity to be achieved with scalar codes which involves significantly less complexity in practice than vector coding.     

Prediction of Critical Desalination Parameters Using Radial Basis Functions Networks

Prediction of critical desalination parameters (recovery and salt rejection) of two distinct processes based on real operational data is presented. The proposed method utilizes the radial basis function network using data clustering and histogram equalization. The scheme involves center selection and shape adjustment of the localized receptive fields. This algorithm causes each group of radial basis functions to adapt to regions of the clustered input space. Networks produced by the proposed algorithm have good generalization performance on prediction of non-linear input–output mappings and require a small number of connecting weights. The proposed method was used for the prediction of two different critical parameters for two distinct Reverse Osmosis (RO) plants. The simulation results indeed confirm the effectiveness of the proposed prediction method.     

CMOS wideband analogue delay stage

A new second-order all-pass filter with maximum achievable delay-bandwidth-product (DBW) is presented. The proposed circuit will be used as a wideband delay element in impulse radio ultra-wideband transceivers. Benefiting from a simple architecture, the proposed circuit achieves a 60 ps delay across a 10 GHz bandwidth, which is the largest delay ever reported over such a wide bandwidth. In addition, the most noticeable advantage of this delay circuit is the small variation of group delay across a wide frequency range, which means negligibly small phase distortion introduced by the circuit     

COGNITIVE RADIOS FOR DYNAMIC SPECTRUM ACCESS - The Throughput Potential of Cognitive Radio: A Theoretical Perspective

Cognitive radios are promising solutions to the problem of overcrowded spectrum. In this article we explore the throughput potential of cognitive communication. Different interpretations of cognitive radio that underlay, overlay, and interweave the transmissions of the cognitive user with those of licensed users are described. Considering opportunistic communication as a baseline, we investigate the throughput improvements offered by the overlay methods. Channel selection techniques for opportunistic access such as frequency hopping, frequency tracking, and frequency coding are presented. The trade-off between regulation and autonomy inherent in the design and performance of cognitive networks is examined through a simple example, which shows that the optimal amount of licensing is equal to the duty cycle of the traffic arrivals