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List of Articles
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Open Access Article
1 - Experimental Study and Comparison of a Few Lean (gasoline-natural gas) Dual Fuels Based on Safe Optimum Spark Advance
سیدکاظم یکانی ابراهیم عبدی اقدم مهرداد سرابیStrong dependence of the human’s daily life on the engine-powered vehicles, increasing environmental pollutions, especially in urban areas, and reduction of the world oil resources have challenged the energy researchers to make appropriate decisions at regional sc MoreStrong dependence of the human’s daily life on the engine-powered vehicles, increasing environmental pollutions, especially in urban areas, and reduction of the world oil resources have challenged the energy researchers to make appropriate decisions at regional scale for selecting alternative fuels to improve the engine efficiency and fuel economy. In the current work, the lean-burn idea jointed to dual (gasoline-NG) fuel has been considered to develop the SI engines. To investigate the performance and exhaust gas emissions, experimental tests were performed using a single-cylinder research engine with gasoline-NG dual fuels, including four mass-based blends of the two fuels (G100, G87.5, G75, and G62.5 containing gasoline at 100‎\‎%, 87.5\%, 75\%, and 62.5\%, respectively, with the remaining part being composed of NG), at 1800 rpm ES and 0.9 ER under at least seven different SAs. The result showed that increasing the NG fraction in the fuel blend, both the σ and COV of imep decreased. It was implicitly observed that, for blended fuels, non-uniform distribution of each fuel can serve as a new source for cyclic variations. Under the considered lean burning condition at optimal safe SA, the imep and output torque for the gas-contained fuel blends were comparable to those obtained by the pure gasoline. Also, it was detected that an increase in the CR reduced the emitted amounts of HC and CO ‎pollutants.‎ Manuscript profile -
Open Access Article
2 - Provide a New Model for Evaluating and Ranking DMUs With Ordinal Data
جعفر پورمحمود داود نوروزیClassic Data Envelopment Analysis assumes that the values of inputs and outputs are exactly determined. However, in most real-life problems, the exact values of some of the inputs and outputs are imprecise. One of such imprecise data is ordinal data. In this paper, a ne MoreClassic Data Envelopment Analysis assumes that the values of inputs and outputs are exactly determined. However, in most real-life problems, the exact values of some of the inputs and outputs are imprecise. One of such imprecise data is ordinal data. In this paper, a new model is presented for measuring the efficiency evaluation of decision making units with ordinal data. The general idea of this model is assigning real values to ordinal data with new approach. Furthermore, another new model for ranking efficient units is presented with the main idea of changes in controlled efficiency. Then, the results of proposed model are compared with Cooper model. Therefore, the efficiency scores obtained from proposed model are more realistic and reasonable than the results obtained from the Cooper's model. Manuscript profile -
Open Access Article
3 - An Improvement on Collocation Algorithm to Solve Initial Value Problems
مهران نیکآریا سعید سرآبادانIn this paper an improved version of the collocation method is proposed to solve ordinary differential equations with initial conditions. Our proposed algorithm is described by applying it to some well-known IVPs. The results are compared with basic collocation algorith MoreIn this paper an improved version of the collocation method is proposed to solve ordinary differential equations with initial conditions. Our proposed algorithm is described by applying it to some well-known IVPs. The results are compared with basic collocation algorithms to show the advantages, applicability and efficiency of the proposed method. Based on numerical results, the proposed algorithm has better accuracy and execution time. Manuscript profile -
Open Access Article
4 - The Application of Private Blockchain to Increase Security in IoT
رضوان محمودیه سعید پارسا امیر مسعود رحمانیBlockChain (BC) has gotten a lot of interest because of its immutability and accompanying security and privacy benefits. BC has the potential to address the Internet of Things' security and privacy issues (IoT). BC, on the other hand, is computationally expensive, has l MoreBlockChain (BC) has gotten a lot of interest because of its immutability and accompanying security and privacy benefits. BC has the potential to address the Internet of Things' security and privacy issues (IoT). BC, on the other hand, is computationally expensive, has limited scalability, and incurs significant bandwidth overheads and delays, making it unsuitable for use in the IoT. In this study, we propose a method that optimizes BC for use in IOT environment. we present a hierarchical structure that uses a private BC to increase scalability, reduce network overhead and delay. In the proposed method, devices with high-level resources build a network referred to as the overlay network on devices with low-level resources. The members of the overlay network manage the BC. The arrangement of the block managers at the overlay network level is two-dimensional which removes the focus from IOT management. We use trust technique and voting from direct neighbors to reduce network traffic and overhead costs. The use of factors such as trust, encouragement and penalty of block managers in the overlay network ensures accurate transactions in IOT. We use the new block manager authentication algorithm for authentication in the overlay network. The simulation results show that the proposed algorithm reduces packet overhead and delay in service delivery and increases the scalability of the BC in comparison to the system that uses the base BC. Furthermore, because in the proposed algorithm, the number of effective block managers in voting is limited to direct neighbors, the average time to confirm a block is significantly reduced. Manuscript profile -
Open Access Article
5 - Classifying Flexible Measures in Two-Stage Network DEA
سیده نسرین حسینی منفرد محمدرضا مظفری محسن رستمی مال خلیفهIn this paper we propose FNDEA models based on the multiplier model under constant returns to scale (CRS) and variable returns to scale (VRS) in general two-stage network structures to classify flexible measures, in which each one of the flexible measure is treated as e MoreIn this paper we propose FNDEA models based on the multiplier model under constant returns to scale (CRS) and variable returns to scale (VRS) in general two-stage network structures to classify flexible measures, in which each one of the flexible measure is treated as either input or output to maximize the overall network efficiency of the DMU under evaluation. Manuscript profile -
Open Access Article
6 - A Multi-Objective Green Supply Chain: Multi-Product Model Considering Uncertainty
داوود خدادادیان رضا رادفر عباس طلوعی اشلاقیThe purpose of this research is to provide a mathematical model for designing the purchase, production, and distribution in a multi-level and multi-product supply chain network such that the environmental impact and total costs of supply chain is minimized and the custo MoreThe purpose of this research is to provide a mathematical model for designing the purchase, production, and distribution in a multi-level and multi-product supply chain network such that the environmental impact and total costs of supply chain is minimized and the customers' satisfaction level is maximized. According to the results, the proposed NSGAII is a reliable method to find efficient Pareto frontiers in a reasonable time. Manuscript profile -
Open Access Article
7 - Numerical Study of Two Reaction Mechanisms on Delft Flame III Using Large Eddy Simulation and Conditional Moment Closure Approach
مهدی زکیانی رودسریA conditional moment closure model is adopted together with a state-of- the-art LES approach to simulate the target flame of the TNF workshop, Delft piloted methane flame III. For modeling the sub-grid scales, the constant Smagorinky model and the Dynamic Wale model are MoreA conditional moment closure model is adopted together with a state-of- the-art LES approach to simulate the target flame of the TNF workshop, Delft piloted methane flame III. For modeling the sub-grid scales, the constant Smagorinky model and the Dynamic Wale model are used in this study. First order conditional moment closure is used to model the turbulence-chemistry interaction. To calculate the conditional velocity, conditional volume averaging with smoothing is used. Two different models are used for computing the conditional scalar dissipation. One is the same procedure for the calculating conditional velocity i.e., volume averaging, and the other is to use Amplitude Mapping Closure model. A second order time accurate predictor-corrector method is used for time integration of the Favre filtered Navier-Stokes equations. Manuscript profile
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