A simulated annealing algorithm for multi-manned assembly line balancing problem

Assembly line balancing problems with multi-manned workstations usually occur in plants producing high volume products (e.g. automotive industry) in which the size of the product is reasonably large to utilize the multi-manned assembly line configuration. In these kinds of assembly lines, usually there are multi-manned workstations where a group of workers simultaneously performs different operations on the same individual product. However, owing to the high computational complexity, it is quite difficult to achieve an optimal solution to the balancing problem of multi-manned assembly lines with traditional optimization approaches. In this study, a simulated annealing heuristic is proposed for solving assembly line balancing problems with multi-manned workstations. The line efficiency, line length and the smoothness index are considered as the performance criteria. The proposed algorithm is illustrated with a numerical example problem, and its performance is tested on a set of test problems taken from literature. The performance of the proposed algorithm is compared to the existing approaches. Results show that the proposed algorithm performs well.     

Optimal matching by the transiently chaotic neural network

Dynamic programming matching (DPM) is a technique that finds an optimal match between two sequences of feature vectors allowing for stretched and compressed sections of the sequence. The purpose of this study is to formulate the matching problem as an optimization task and carry out this optimization problem by means of a chaotic neural network. The proposed method uses TCNN, a Hopfield neural network with decaying self-feedback, to find the best-matching (i.e., the lowest global distance) path between an input and a template. Experimental results show a very good performance for the proposed algorithm in pattern recognition tasks.     

One-sided 10T static-random access memory cell for energy-efficient and noise-immune internet of things applications

This paper presents a one-sided 10-transistors static-random access memory (SRAM) cell appropriate for the internet of things (IoT) applications in which energy-efficient SRAM cells are necessary to raise the battery lifetime. The bit-cell core of the proposed SRAM cell is composed of two inverters with different structures based on the gate-wrap-around (GWA) carbon nanotube (CNT)-gate-diffusion input (GDI) technique and only one-bit line to perform both read and write operations to minimize active power consumption. The proposed bit-cell uses a transmission gate network and write-assist schemes to significantly improve the write-ability and stack read-decoupling technique to enhance hold-/read-stability. Moreover, a memory mini-array has been implemented using the proposed cell along with all the principal circuitries. Extensive Monte Carlo (MC) simulations show that write/hold/read static noise margins (SNMs) are improved by about 1.252, 1.196, and 1.152 times, respectively. Also, the results of evaluating the write- and read-yield parameters for the proposed SRAM bit-cell are about 22% and 13% better than counterpart bit-cell designs, respectively. In addition, the bit error rate (BER) and energy dissipation parameters for the proposed memory cell are almost 61% and seven times higher than the studied SRAM bit-cell in the same simulation process. Finally, to evaluate the effectiveness of the proposed SRAM bit-cell in the real-world application, a memory array architecture with an online (or off-chip) adaptive power supply voltage based on a hardware algorithm for storing digital images at a minimum energy dissipation is proposed. Our simulation results emphasize that the proposed memory array can be a good candidate for energy-efficient and noise-immunity IoT platforms.     

Efficiency improvement of genetic network programming by tasks decomposition in different types of environments

Genetic Programming and Evolvable Machines - Genetic Network Programming (GNP) is a relatively recently proposed evolutionary algorithm which is an extension of Genetic Programming (GP). However,...     

Toward mechanistic understanding the effect of aspect ratio of carbon nanotubes upon different properties of polyurethane/carbon nanotube nanocomposite foam

This study investigated the carbon nanotube's aspect ratio's influence on the nanocomposite foams' cellular structure and mechanical, acoustic absorption characteristics. The free-rising foaming process has been used for producing different flexible polyurethane (PU) foams embedded with other multi-walled carbon nanotubes (MWCNT's). Dynamic mechanical and thermal analysis, flow resistivity, and compressive mechanical measurements were achieved on the prepared samples. The acoustic absorption coefficient in a wide range of frequencies was estimated for the prepared PU/CNT foamed nanocomposite samples. Results indicated that by increasing the aspect ratio of MWCNT, the absorption coefficient's peak shifts toward the lower frequencies and improved sound absorption characteristics of PU foam in the low-frequency region. Moreover, the Young modulus of nanocomposite samples increases by increasing the aspect ratio of MWCNT's, whereas the stored strain energy or area under the stress–strain curve increases. Based on the obtained results, it is observed that the acoustic absorption coefficient of produced nanocomposite foams at the frequency of 800 Hz has been reported to have a 70% improvement in 2 cm samples and a 40% improvement in 3 cm samples compared to obtained results from pure PU foam.     

Development of the TIGRE Compton telescope for intermediate-energy gamma-ray astronomy

Gamma-ray observations in the low and medium energy range (0.1-100 MeV) with sufficiently sensitive telescopes will provide unique insights into many outstanding high-energy astrophysics questions. The University of California, Riverside (UCR) Tracking and Imaging Gamma-Ray Telescope (TIGRE) Compton gamma-ray telescope uses multilayers of silicon strip detectors to, for the first time, track the Compton electron and CsI(Tl)-photodiode detectors to measure the scattered photon energy. By combining the Compton telescope's inherent imaging capability with improved background discrimination, a larger field-of-view and improved spectral and spatial resolutions, a significant improvement in sensitivity over Compton Gamma-Ray Observatory (CGRO) and INTEGRAL can be achieved. The well-type calorimeter design also enhances the instrument as a gamma-ray polarimeter. The development and flight of a robust Compton telescope represents a unique opportunity to continue the momentum of recent discoveries in low and medium energy gamma-ray astrophysics with CGRO and an absolutely essential step to an extended satellite mission by 2010.     

Investigation of Interfacial Tension Reduction,Wettability Alteration,and Oil Recovery Using a New Non-ionic Oil-Based Surfactant from Gemini Surfactants Family Coupled with Low-Salinity Water: Experimental Study on Oil-Wet Carbonate Rock

Low-salinity surfactant (LSS) flooding is a combined enhanced oil recovery (EOR) technique that increases oil recovery (OR) by altering the rock surface wettability and reducing oil–water interfacial tension (IFT). In this study, optimum concentrations of several types of salt in distilled water were obtained on the basis of IFT experiments for the preparation of low-salinity water (LSW). Then, a new oil-based natural surfactant (Gemini surfactant, GS) was combined with LSW to investigate their effects on IFT, wettability, and OR. Experimental results showed that LSW is capable of reducing IFT and contact angle, but the synergy of GS and the active ions Mg²⁺, Ca²⁺, and SO₄²⁻ in LSW was more effective on IFT reduction and wettability alteration. The combination of 1000 ppm MgSO₄ and 3000 ppm GS led to a decrease in contact angle from 134.82° to 36.98° (oil-wet to water-wet). Based on core flooding tests, LSW injection can increase OR up to 71.46% (for LSW with 1000 ppm MgSO₄), while the combination of GS and LSW, as LSS flooding, can improve OR up to 84.23% (for LSS with 1000 ppm MgSO₄ and 3000 ppm GS). Therefore GS has great potential to be used as a surfactant for EOR.     

An approximate analytical framework for performance analysis of equal gain combining technique over independent Nakagami,Rician and Weibull fading channels

In this paper, an approximate analytical method for performance analysis of equal gain combiner (EGC) receiver over independent Nakagami and Rician fading channels is presented. We use a convergent infinite series approach which makes it possible to describe the probability of error of EGC receiver in the form of an infinite series. In this paper, we develop a new approximation method for computation of the required coefficients in this series which lets us to derive simple analytical closed-form expressions with good accuracy compared with the exact results existing in the literatures. Our proposed approximation method only needs the mean and the variance of the fading envelope, which are known for various fading distributions, and hence, bypasses the required integration over the fading envelope distribution while computing the required coefficients. This feature lets us to extend our approximation method for performance analysis of EGC receiver over independent Weibull fading channels where the required integration has not any closed-form or tabulated solutions. To give an application of our developed method, we analyze the probability of error of an EGC receiver for binary, coherent PSK (CPSK) modulation over independent Nakagami, Rician and weibull fading channels and study the effect of the fading conditions on the system performance.     

Design and performance of an EMI filter to reduce conducted EMI in an isolated full bridge buck converter power supply

EMI Filter Design and Performance for isolated full bridge buck cunverter is developed in this paper.In order to design a high performance EMI filter, many issues need to be considered beforehand. Some important issues including accurate model of converter components, parasitic elements, its effect on EM1 noise and impedance mismatch are included in this paper. A numerical prediction of EML/EMC has the potential to evaluate EMI performances at the design stage and before prutotyping. It can also help reduce the post-prototype EMC cost by minimizing late redesign and modifications of a design implementation. Saber simulator is used to analyze the EMI noises and EMI filter‘s performance. Conducted EMI noise measurement and EM1 filter design of isolated full bridge buck converter has been achieved while successfally satisfying the FCC class B limits in the frequency range from 150 kHz to 30 MHz. Simulation results are compared with experimental data and the effectiveness of the EMI simulation approach is demonstrated.