Performance evaluation of a routing algorithm based on Hopfield Neural Network for network-on-chip

Network on chip (NoC) has emerged as a solution to overcome the system on chip growing complexity and design challenges. A proper routing algorithm is a key issue of an NoC design. An appropriate routing method balances load across the network channels and keeps path length as short as possible. This survey investigates the performance of a routing algorithm based on Hopfield Neural Network. It is a dynamic programming to provide optimal path and network monitoring in real time. The aim of this article is to analyse the possibility of using a neural network as a router. The algorithm takes into account the path with the lowest delay (cost) form source to destination. In other words, the path a message takes from source to destination depends on network traffic situation at the time and it is the fastest one. The simulation results show that the proposed approach improves average delay, throughput and network congestion efficiently. At the same time, the increase in power consumption is almost negligible.     

Correction to: Monitoring and Predicting Saltwater Intrusion via Temporal Aquifer Vulnerability Maps and Surrogate Models

Water Resources Management -     

Micro thermoelectric cooler: Planar multistage

A suspended, planar multistage micro thermoelectric (TE) cooler is designed using thermal network model to cool MEMS devices. Though the planar (two-dimensional) design is compatible with MEMS fabrication, its cooling performance is reduced compared to that of a pyramid (three-dimensional) design, due to a mechanically indispensable thin dielectric substrate (SiO₂) and technical limit on TE film thickness. We optimize the planar, six-stage TE cooler for maximum cooling, and predict ΔT_max = 51 K with power consumption of 68 mW using undoped, patterned 4–10 μm thick co-evaporated Bi₂Te₃ and Sb₂Te₃ films. Improvement steps of the planar design for achieving cooling performance of the ideal pyramid design are discussed. The predicted performance of a fabricated prototype is compared with experimental results with good agreements.     

Platinum-palladium nanoparticles-loaded on N-doped graphene oxide/polypyrrole framework as a high performance electrode in ethanol oxidation reaction

Existing catalysts for ethanol oxidation in direct ethanol fuel cells (DEFC) are faced to significant challenges due to their poor performance and CO like intermediates poisoning tolerance at anode surface. Hence researchers are looking for new electrocatalysts in the ethanol oxidation. In this study, polypyrrole/N-doped graphene oxide (PPy/NGO) nanocomposite was prepared using in-situ polymerization method. Next the platinum-palladium (PtPd) was electrochemically decorated on PPy/NGO nanocomposite surface. In order to ensure the correct preparation of nanocomposite, fourier transform infrared spectroscopy (FT-IR) analysis was carried out to peruse the chemical structure of the nanocomposite and also to investigate their morphology, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used. The morphology of nanocomposite shows that PPy has penetrated into the space between NGO plates. Disparate electrochemical techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) were employed to evaluate the oxidation of ethanol. Results showed that PtPd/PPy/NGO exhibits improved electrocatalytic activity and stability for ethanol oxidation. Enhanced active surface area of the PtPd/PPy/NGO electrode (35.1 m² g^?1) contributes to increase in current density and decrease in over potential values in the ethanol oxidation as compared to PtPd electrocatalyst.     

Effect of reformed biogas as a low reactivity fuel on performance and emissions of a RCCI engine with reformed biogas/diesel dual-fuel combustion

Biogas can be used as a less expensive continuance renewable fuel in internal combustion engines. However, variety in raw materials and process of biogas production results in different components and percentages of various elements, including methane. These differences make it difficult to control the combustion, effectively, in internal combustion engines. In this research, under cleaning and reforming process, biogas components were fixed. Then the effect of reformed biogas (R.BG) was investigated, numerically, on the combustion behavior, performance and emissions characteristics of a RCCI engine. A 3D-computational modeling has been performed to validate a single-cylinder compression ignition engine in conventional diesel and dual-fuel operations at 9 bar IMEP, 1300 rpm. Then, the combustion model of the RCCI engine was simulated by replacing diesel fuel with 20%, 40% and 60% of R.BG as a low reactivity fuel while remaining constant input total fuel energy per cycle. The results demonstrated that when the R.BG substitution ratio increases with a constant equivalence ratio of 0.43, the mean combustion temperature decreases to 1354 K, 1312 K, 1292 K which are about 3.5%, 6.6%, 7.9% lower than the conventional diesel combustion, respectively. The maximum in-cylinder pressure increases up to 22.63%. Instead, it results in 2.3%, 7.9%, and 14.5% engine power output losses, respectively. Also, the NOx emission, against CO, is decreased by 50%. Soot and UHC emissions were found to be slightly decreased while was used R.BG more than 40%.     

Structural performance evaluation of an aged structure using a modified plasticity model in inverse solution method

In this research, the trends of degradation of stiffness and compressive strength of mass concrete of the Dez concrete arch dam, over time have been evaluated using a new and robust method. In previous studies of the corresponding author, he was successful to estimate the degradation of the stiffness of dam’s concrete at the end of a selected time interval, i.e. the Year 2007 from the interval 1965–2007 using a novel thermal inverse analysis. But, he was interested in knowing the trend of this degradation over that time interval. In previous studies, the author used isotropic and transversely isotropic elastic material models for evaluating the stiffness degradation. By these material models, the reduction of the compressive strength of the mass concrete could not be determined. In this new attempt, to overcome the above-mentioned shortcomings, it was decided that the time interval is limited to a maximum of one year from 1965 to 2007. In addition, a more sophisticated material model for concrete of the dam, named as, concrete damaged plasticity model, from the ABAQUS standard material library, was employed to simulate the long-term concrete behaviour. By this material model, the reduction of the compressive strength of the dam’s concrete could be measured. Obtained results demonstrated that the reduction of stiffness and strength of dam’s concrete have not a constant rate of change and they have been accelerated considerably after passing approximately 20 years from the commissioning of the dam.     

Optimization of Pump Scheduling Program in Water Supply Systems Using a Self-Adaptive NSGA-II; a Review of Theory to Real Application

The operation of pumps imposes significant costs on a water distribution system for energy supply and pumps maintenance. To derive an optimum pumps scheduling program, this study presents a multiobjective optimization problem with the objective functions of 1- energy cost and 2- the number of pump switches. The optimization of both objective functions together leads to a multiobjective constrained optimization problem. To solve the problem, the Non-Dominated Sorting Genetic Algorithm, version II, (NSGA-II) is coupled to the EPANET hydraulic simulation model. For constraint handling, some modifications are introduced to the standard NSGA-II to make it self-adaptive through which all constraints of the problem are automatically satisfied. Application of the model to a test example and a real pipe network verifies that the proposed scheme is computationally efficient and reliable. Also, optimization of the real pipe network reveals that by a careful pump scheduling program the total number of pump switches even in optimum operations could be decreased by 69% while the energy cost increases at most by 10%.     

Preparation and characterization of PAn/NiO nanocomposite using various surfactants

Conducting nanocomposite of NiO–PAn has been prepared in the aqueous medium using polyvinyl alcohol and hydroxypropylcellulose as a surfactant. The conductivity of the composites was measured as a function of the NiO concentration in reaction solution. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and electrical resistivity proved that NiO affect the properties of composite.