Optimization of transmitter and receiver filters for digitalcommunication systems using mean field annealing

A technique for finding transmitter and receiver filters for a wide class of digital communication systems which minimize the bit-error rate (BER) is presented. The technique uses Monte Carlo simulation to estimate the BER and mean field annealing (MFA) to optimize the pulse shapes. Modeling of the link can be as complex as simulation will allow, while MFA is resistant to the statistical variation in the BER estimate from the simulation. Initially, the MFA technique was applied to a binary symmetric channel in a nonsimulation environment, and an approximate analysis of the behavior of MFA for this problem was performed. In a more complex example, MFA was coupled with Monte Carlo simulation techniques to find near-optimal transmit and receive filters for a satellite communications link, taking 6 CPU hours on a DECstation 3100. The BER of the link was found to be as much as three orders of magnitude lower when using the MFA-constructed optimal filters than when using filters from other comparison results. For this example, the pulse shapes obtained using MFA exhibit a low BER even as the parameter controlling the nonlinearity of the satellite-link model is varied over a wide range, thus showing the solution is robust     

Optimal pulse shape design for digital communication systems byprojections onto convex sets

Recent developments in DSP hardware has made it possible to use almost any pulse shape for digital data transmission. This resulted in a search for algorithms capable of constructing pulse shapes matching to the properties of a given channel. The projection onto convex sets technique is suitable for the solution of this problem particularly because of its flexibility in modeling a variety of constraints. The use of the technique for the optimal pulse shape design problem is demonstrated through a detailed example from power line communications     

A parametric study on natural gas fueled HCCI combustion engine using a multi-zone combustion model

Homogenous Charge Combustion Ignition (HCCI) is a good method for higher efficiency and to reduce NOx and particulate matter simultaneously in comparison to conventional internal combustion engines. In HCCI engines, there is no direct control method for auto ignition time. A common way to indirectly control the ignition timing in HCCI combustion engines is varying engine’s parameters which can affect the combustion. In this work, a parametric study on natural gas HCCI combustion is conducted in order to identify the effect of inlet temperature and pressure, compression ratio, equivalence ratio and engine speed on combustion and engine performance parameters. In this paper, two kinds of parameters will be discussed. First, in-cylinder pressure diagrams and variation of start of combustion which are combustion parameters will be presented and then the second category, indicated mean effective pressure and thermal efficiency which are performance parameters will be studied. A six zone model coupled with detailed chemical kinetics code is used to simulate HCCI combustion. Both heat and mass transfer was considered in the modeling procedure. Results revealed that among the considered parameters, the equivalence ratio and inlet pressure are the most valuable parameters which can improve the combustion and performance characteristics of the HCCI engine.     

Action space noise optimization as exploration in deterministic policy gradient for locomotion tasks

Applied Intelligence - Reinforcement learning (RL) algorithms with deterministic actors (policy) commonly apply noise to the action space for exploration. These exploration methods are either...     

Effect of nanoclay on fatigue life of hot mix asphalt

The aim of this research is to investigate effect of two types of nanoclay additives, namely Cloisite 15-A and Cloisite 30-B, on fatigue life of asphalt mixes. Indirect tensile-resilient modulus and four-pointed beam fatigue tests were employed for this purpose. Results of both tests indicated that nanoclay additives improve fatigue life at 25°C but they have negative impact on it at 5°C. Moreover, Cloisite 15-A was found more effective at both temperatures regarding fatigue life.     

Deep extractive desulfurization of oil over 12-molibdophosphoric acid encapsulated in metal-organic frameworks

A desulfurization process for model oil and real oil was investigated based on the chemical oxidation of mixed sulfur containing compounds in the presence of nitrogen compounds (indole and quinoline) using hydrogen peroxide as oxidizing agent and dodecamolibdophosphoric acid (H₃PMo₁₂O₄₀) encapsulated in a kind of metal-organic framework (HKUST-1) as PMo@HKUST-1. The effect of isopropanol, ethanol and acetonitrile as extractive solvent and 1-ring (toluene, xylene and mesitylene) and 2-ring (naphthalene) aromatic hydrocarbons in desulfurization of model oil was studied. The desulfurization of sulfur-containing compounds was accelerated in the presence of aromatic hydrocarbons. In fact, a higher desulfurization efficiency of the heterogeneous catalyst could be achieved with system containing a polar solvent in contact with an aromatic hydrocarbon. Quinoline had no effect on oxidative desulfurization (ODS) reaction, whereas indole had a slightly negative effect. Presence of aromatic compounds had slightly positive effect on ODS reaction.     

Application of Taguchi approach in describing the mechanical properties and thermal decomposition behavior of poly(vinyl chloride)/clay nanocomposites: Highlighting the Role of organic modifier

Mechanical and thermal properties of poly(vinyl chloride) (PVC)/nanoclay (NC) composites prepared via melt‐blending in a single‐screw extruder were investigated. The effects of NC type, NC content, and K‐value of PVC were evaluated by using L9 orthogonal array of the Taguchi approach. The most influential variables and significance of interactive effects were examined for the highest values of Young's modulus and hardness. Scanning electron micrographs and X‐ray diffraction patterns revealed the formation of exfoliated/intercalated structures. Although the K‐value has a minor individual effect on mechanical characteristics, the interaction of the K‐value with NC type and NC content is significant. The composites were also characterized and tested by using analysis by thermal gravimetry, differential thermogravimetry, and differential scanning calorimetry methods. The results of the thermal studies indicated that decomposition of the organic modifier of NCs has a catalytic effect on the dehydrochlorination of PVC. This finding justifies the rather low mechanical properties of PVC/organoclay nanocomposites. Fourier‐transform infrared spectra of the samples were indicative of accelerated degradation reactions, which provided support for above observations. J. VINYL ADDIT. TECHNOL., 22:182–190, 2016. © 2014 Society of Plastics Engineers     

Mechanistic-empirical methodology for the selection of cost-effective rehabilitation strategy for flexible pavements

A well-planned rehabilitation approach helps agencies to optimise the allocation of annual investment in pavement rehabilitation programs. Currently, many agencies are struggling with the selection of an optimal time-based and cost-effective rehabilitation solution to address the long-term needs of pavements. This study offers the use of a mechanistic-empirical methodology to develop a series of time-based rehabilitation strategies for high traffic volume flexible pavements located in Oklahoma. Six different pavement family groups are identified in the state, and comprehensive evaluation of existing pavements are conducted through analysis of falling weight deflectometer data and performance measures available in Oklahoma Pavement Management System database. The inadequacy of performance measures to fully characterise the condition of existing pavements are indicated, and damage factor determined from FWD data are suggested as trigger factor to select rehabilitation candidates. Three levels of rehabilitation activities including light, medium and heavy are considered as potential alternatives for rehabilitation candidates. A mechanistic-empirical methodology is employed to obtain an estimate of the performance of rehabilitation and extension in service lives of pavements. Also, an assessment output matrix is developed, which can be served as a supplemental tool to help the decision-makers in the highway agency with the rehabilitation related decision-making process. Cost-effectiveness of rehabilitation alternatives is determined through life cycle cost analysis, and three time-based renewal solutions are developed for pavement family groups that are in need of rehabilitation.     

Effects of nanoclay on hot mix asphalt performance

The purpose of this study was to evaluate of nanoclay effects as an additive on performance of asphalt mixtures. Two types of montmorillonite nanoclay, namely CA and CB, were used at concentrations of 2%, 4%, and 6%. Marshall, indirect tensile strength, resilient modulus, and dynamic creep tests were performed to investigate the effect of additives on moisture susceptibility, structural response, and rutting resistance. The results showed improvement of the asphalt mixture performance by adding nanoclay with respect to all tests. According to the results, samples containing nanoclay CA have better performance in comparison with the samples containing CB.     

Development of a Dynamometer to Measure All Forces and Moments Applied on Tillage Tools

A new triaxial dynamometer was designed, constructed and tested to measure and locate the position of all forces and moments on tillage implements, up to a maximum force of 10 kN and a maximum moment of 10 kN × m. The design concept of the facility was based on four frames attached to each other by load cells and tillage tool were attached on the inner frame. Calibration of the system showed the reliable and precise performance of the dynamometer in tracking the forces and moments. Additionally, the designed setup operated desirably under field conditions. Draft measurement was compared to those predicted by ASABE Standard D497.7 and was found to be in standard range. By using the new facility, it would be possible to study the relationship between forces and moments at the varying practical cases and design of tines, toolbars and tillage equipments in regard to the soil type and available tractor power will be facilitated.