Showing 229–240 of 1843 results
Energy optimization of ant colony algorithm in wireless sensor network
An energy consumptioرایگان!
An energy consumption optimization algorithm based on ant colony algorithm is proposed for wireless sensor network. The proposed algorithm allows each node in wireless sensor network to save the distance and residual energy of neighbor nodes. Furthermore, in terms of probability selection of the nodes and the pheromone update, this algorithm focuses on the next hop node through the comparison of distance between the nodes and the residual energy, which ensures less possibility of nodes with low energy selected as the next hop. Therefore, the proposed algorithm improves energy load balancing, stability of wireless sensor network and, eventually, extends the life span of the wireless sensor network. The simulation results show that the improved ant colony algorithm avoids too much energy consumption of acertain local node resulting in more uniform energy consumption for each node.
Enhancing Road Tunnel Risk Assessment with a Fuzzy System Based on the CREAM Methodology
A great increase hasرایگان!
A great increase has been noticed in the number of road tunnels in Europe over the last decades.
Enhancing Road Tunnel Risk Assessment with a Fuzzy System Based on the CREAM Methodology
A great increase hasرایگان!
A great increase has been noticed in the number of road tunnels in Europe over the last decades. This can be attributed to the improvement of tunnel construction technology which has rendered tunnels a cost effective solution to connect steep mountainous regions and traverse urban areas. However, the increasing number of these infrastructures is a double-edged sword raising upfront an endogenous problem too, which is the severity of accidents that may occur in them. Accidents in road tunnels may lead to heavy consequences for the users, the infrastructure itself and the environment. Within this context the European Commission launched the Directive 2004/54/EC that sets basic requirements and suggests the implementation of a risk assessment in several cases apart from the measures imposed based on tunnel length and traffic volume. Since the EU Directive does not indicate the method for performing the risk assessment a wide range of methods have been proposed, most of them based on Quantitative Risk Assessment (QRA). Although the majority of current road tunnel QRAs assess physical aspects of the tunnel system and consider several hazards concerning the transportation of dangerous goods (DGs) through a tunnel, they do not take into account several organizational and human factors that can greatly affect the overall safety level of these critical infrastructures. To cope with this limitation this paper proposes a fuzzy logic system based on CREAM methodology in order to provide more sophisticated estimations of the tunnel operator’s performance in safety critical situations. This paper couples the results produced by the fuzzy logic system with the input parameters for a road tunnel QRA model (namely the OECD/PIARC DG-QRA Model). The results from the analysis reveal that the estimations of the tunnel operator’s performance produced by the fuzzy system significant affect the results of the road tunnel QRA. Therefore, it is deduced that the proposed fuzzy system can serve as a useful tool for the analyst to consider organizational and human factors so as to enhance the analysis and highlight the uncertainty related to human performance variability
European Option Pricing with Transaction Costs
This paper deals witرایگان!
This paper deals with the construction of a finite difference scheme for a nonlinear BlackScholes partial differential equation modelling stock option pricing in the realistic case when transaction costs arising in the hedging of portfolios are taken into account. The analysed model is the Barles-Soner one.
Evaluating management training and development in a cross-cultural context A stakeholder approach
Purpose – The purposرایگان!
Purpose – The purpose of this paper is to address the challenge in evaluating China’s overseas management training and development (MTD) in cross-cultural settings. It examines the evaluation practice of China’s overseas MTD interventions and explores a comprehensive approach to the MTD evaluation. Design/methodology/approach – This study collected both quantitative and qualitative data from 526 major stakeholders involved in China’s overseas MTD. A mix method approach is used to explore the perspectives of different stakeholders. Findings – The respondents from different stakeholder groups perceived purposes of evaluation and problems conducting evaluation differently. The perceived evaluation criteria and approaches by individual group were also focused differently. The current evaluation system was based on
segmented information collection and little joint effort was found in the MTD evaluation. The judgement on the value of China’s overseas MTD is culturally sensitive due to the diversity of stakeholders from different cultural backgrounds. A new framework is proposed to address the evaluation challenge. Research limitations/implications – This study is limited to evaluating China’s MTD between China and the UK. The valuation framework is based on complex involvement of multiple stakeholders in an international setting. It may not be applicable to situations where only two parties are involved in training. Practical implications – The proposed stakeholder-based evaluation framework may be used for other skill-based training and development programs involving multiple stakeholders in the international arena. Originality/value – This paper contributes to the HRM evaluation literature by focusing on a unique evaluation setting and proposes a framework to evaluate a complex international MTD initiative by the Chinese Government. Keywords China, United Kingdom, Stakeholder analysis, Cross cultural studies, Training evaluation, Management development Paper type Research paper
Evaluation of Base Shear Absorption of Combined System; RC Frame & Precast 3d Panels with Irregularities in Vertical
The current study inرایگان!
The current study investigates the base shear absorption of combined systems, RC frame pre-cast 3D wall sandwich panels in both linear and non-linear material properties. The seismic behavior of building constructed by 3D panels is studied using numerical approach finite element method. The obtained results are compared with regular bending RC frames, complete box type sandwich wall panels system, and present the differences of behavior and absorbance in each system and also the variation of vertical stiffness on structural response is examined. The material nonlinearities simulated with drucker-prager and von-misses failure criteria. The validation of FEM analysis is test with those obtained through experimental
Evaluation of Horizontal Seismic Hazard of ABADE, Iran
This paper presentsرایگان!
This paper presents probabilistic horizontal seismic hazard assessment of Abade, Iran. It displays the probabilistic estimate of Peak Ground Horizontal Acceleration (PGHA) for the return period of 475 and 2475 years. The output of the probabilistic seismic hazard analysis is based on peak ground acceleration (PGA), which is the most common criterion in designing of buildings. A catalogue of seismic events that includes both historical and instrumental events was developed and covering the period from 840 to 2007 is used. he seismic sources that affect the hazard in Abade were identified within the radius of 150 km and the recurrence relationships of these sources were generated by Kijko and Sellevoll . Finally four maps have been prepared to indicate the earthquake hazard of Abade in the form of iso-acceleration contour lines for different hazard levels by using SEISRISK III
Evaluation of Two Popular Models of Volatility on Financial Time Series
In this paper, we evرایگان!
In this paper, we evaluate and compare two classes of varying volatility model, GARCH and stochastic volatility (SV) models on financial time series. In this case, a closed form estimator for a stochastic volatility model and also its asymptotic properties are considered. Akaike information criterion (AIC) was used to test the adequacy of the models.
Evaluation of various types equations of state for prediction of rate of hydrate formation based on Kashchiev and Firoozabadi model in the presence or absence of kinetic hydrate inhibitors for gasous mixtures in a recirculating systems
This paper comparesرایگان!
This paper compares the effects of using various types of equations of state such as Peng Rabinson(PR), Predictive Soave Ridlich Kowng (PSRK), Benedict–Webb–Rubin-Starling (BWRS), Nasrifar-Boland(NB), and Valderrama -Patel -Teja (VPT) on rate of double gas hydrate formation based on the Kashchiev and Firoozabadi model for gaseous mixtures such as 65% C1/35 %C3, 35% C1/65% C3, 65% C1/35 % i-C4, 35% C1/65% i-C4 with experimental data points obtained in a flow mini-loop apparatus with or without the presence of kinetic inhibitors at various pressures and specified temperature. For the prediction of the gas consumption rate for double gas hydrate formation in a flow mini-loop apparatus, the rate equation based on the Kashchiev and Firoozabadi model for simple gas hydrate formation in bench scale was eveloped. The TAAD% was found to be 18.6 %, 18.8 %, 19.8%, 20.2% and 20.7% for the PR, NB, PSRK, VPT and BWRS equations of state for calculating gas consumption in double gas hydrate formation in the presence and absence of kinetic hydrate inhibitors, respectively. omparison results between the calculated and experimental data points of gas consumption indicate that the PR and NB equations of state have lower errors than the PSRK, VPT and BWRS equations of state for this model
Experimental and Modeling Investigation on Structure H Hydrate Formation Kinetics
In the current work,رایگان!
In the current work, the kinetics of crystal H hydrate formation is modeled by using the chemical affinity model. The experiments were performed at constant temperatures of 274.15, 275.15, 275.65, 276.15 and 277.15 K. Methylcyclopentane (MCP) is used as sH former and methane is used as a help gas. The parameters of model (Ar and tK) are determined and the results show that the parameter of Ar/RT has a constant value at the first step and a different value at second step.These parameters were used to predicting experimental data. The results indicate that this model can predict experimental data very well at several conditions
Experimental investigation of gas consumption for simple gas hydrate formation in a recirculation flow mini-loop apparatus in the presence of modified starch as a kinetic inhibitor
The main objective oرایگان!
The main objective of the present work is to investigate experimentally of simple gas hydrate formation with or without the presence of kinetic inhibitors such as modified starch in a recirculation flow mini-loop apparatus. For this purpose, a laboratory recirculation flow miniloop apparatus was set up to measure the induction time for hydrate formation and gas consumption rate when a hydrate forming substance (such as C1, C3, CO2 and i-C4) is contacted with water in the absence or presence of dissolved inhibitor under suitable temperature and pressure conditions. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make-up. The effect of pressure on gas consumption during hydrate formation is investigated with or without the presence of poly vinylpyrrolidone (PVP) and modified starch as kinetic inhibitors at various concentrations. Our results were shown that the modified starch can be applied as inhibitors in prevention of simple gas hydrate formation in mini-loop apparatus