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Showing 6 results for Hybrid Model


Volume 14, Issue 4 (3-2011)
Abstract

Information systems decisions are of the main concerns of managers. Existence of uncertainties and different objectives and attributes influence the quality of decisions. Environmental uncertainties can challenge the quality of IS investment decisions. Investment decisions, made without any respect to environmental changes, will loose their effectiveness as time passes. IS investment decisions require attention to different attributes such as return on investment, strategic competitiveness and user satisfaction. Multi-attribute decision making (MADM) approaches can play an important role to make investment decisions. This study aims to integrate scenario planning (as a tool to meet environmental uncertainties), Axiomatic Design (MADM approach) and Fuzzy Delphi method (experts opinions acquiring and consensus tool) as a Hybrid Model to propose a new methodology to make IS investment decisions about the outsourcing or insourcing of the development of the information systems. A case study in IS investment has been done. The case is about the selection of an ERP system in Iranian National Oil Company (NOC).
Mahdi Bamdad, Farzin Taheri,
Volume 15, Issue 7 (9-2015)
Abstract

In this paper, a hybrid model which consists of planar parallel robot with a 2-DOF arm is presented. This manipulator is based on cable parallel robots and a kinematic serial chain is utilized and added to a cable parallel chain. The hybrid manipulator can provide features of both serial and parallel mechanism. Understanding the orientability of the end-effector within this workspace gives a measure of the ability of the robot to perform manipulation tasks. Most underactuated parallel manipulators have a low rotational capability. To overcome it, this paper focuses its attention on a new family of serial-parallel manipulators. The initial goal of this design is to increase the orientability capability of a planar two-cable robot. The kinematic and dynamic analysis of this new type hybrid manipulator is presented. The dynamic modeling is performed by using a combination of Lagrange and Newton-Euler methods. This paper conducts the dynamic trajectory planning study to a novel design for the cable robots. In fact, time optimal trajectory planning is a strategy that is used to verify this new design. Two models are considered in the simulation part. A novel hybrid model is compared to a planar parallel cable robot. It is verified that the proposed design allows significantly reduced actuation energy and improved orientability capability compared to the parallel robot.
M. Akbari, A.m. Khoshnood, S. Irani,
Volume 19, Issue 10 (10-2019)
Abstract

Gas turbines have a wide range of application in different industries. There are different models of the gas turbine for its analysis and diagnosis. In this paper, a hybrid model is considered for the gas turbine. This model combines thermodynamic relations and data-based equations which cause to eliminate dynamic loops of thermodynamic relations. Also, the compressor performance curve is considered in the proposed model which leads to noticing physical and geometric characteristic of a gas turbine. The model is dynamic and nonlinear that cause to adapt to a different condition and increase the accuracy of modeling. The model is accurate, simplified and nonlinear state space form. For these reasons, the model is suitable for analyzing of controllers and observers. The proposed controller is a new sliding model controller for implementing in the model. The controller is based on the l_1 norm and frequency analysis. Since the sliding mode is robust and the l_1 norm is optimizer than the l_2 norm, the controller tracks fuel command with acceptable accuracy and minimizing the control fluctuations.
Also, the data that is used in this paper is the data of an industrial gas turbine (IGT25) of Iran's national turbine which is logged in different ambient and functions conditions.
 


Volume 20, Issue 4 (10-2018)
Abstract

Horticulture sector plays a prominent role in economic growth for most of the developing countries. India is the largest producer of fruits and vegetables in the world next only to China. Among the horticultural crops, fruit crops are cultivated in majority of the area. Fruit crops play a significant role in the economic development, nutritional security, employment generation, and overall growth of a country. Among fruit crops, mango and banana are largest producing fruits of India. Generally, Karnataka is called as the horticultural state of India. In Karnataka, mango and banana are highest producing fruit crops. With these prospective, yield of mango and banana of Karnataka have been chosen as study variables. Forecasting is a primary aspect of developing economy so that proper planning can be undertaken for sustainable growth of the country. In this study, classes of linear and nonlinear, parametric and non-parametric statistical models have been employed to forecast yield of mango and banana of Karnataka. The major drawback of linear models is the presumed linear form of the model. In most of the cases, the time series are not purely linear or nonlinear as they contain both linear and nonlinear components. To overcome this problem a hybrid model has been proposed which consists of linear and nonlinear models. The hybrid model with the combination of Autoregressive Integrated Moving Average (ARIMA) and Support Vector Regression model performed better in both model building as well as in model validation as compared to other models.
 

Volume 21, Issue 7 (12-2019)
Abstract

Agricultural ethics has been widely discussed in recent decades. However, in spite of numerous studies there is no consensus on this issue, especially in developing countries. Accordingly, this study was conducted with the aim of the examining farmers’ view on agricultural ethics in Sonqur County, Kermanshah province, Iran. This study used a hybrid model to define the concept of agricultural ethics through three phases. For the theoretical phase, the attributes of agricultural ethics were identified through review of the literature (until 2017). Also, in-depth interviews with 32 participants were conducted for the fieldwork to develop attributes from the data and to verify those identified from the literature review. In the third phase, attributes and final analysis of agricultural ethics were extracted from the first and second phases. Based on the integration of the literature and the results from the interviews, agricultural ethics was described as follows: a complex subject involving farm structure, food security, food safety, global trade, agricultural biotechnology, trust in science, research ethics, environmental impacts, animal ethics, and rights. The scope of agricultural ethics ranges from macro issues at national and global levels to human ecology (human relationship with the environment) of a farmer, suggesting that it has a systemic thinking that is necessary to achieve sustainability.
 
Hesel Gharehbaei, Ali Jahangiri, Mohammad Ameri,
Volume 21, Issue 7 (7-2021)
Abstract

The Heller towers are the most common types Power plants cooling towers، where its efficiency is  is very sensitive to wind. according to the general approach of  designer of cooling systems، Direct dry cooling (ACC) systems are more popular today in power plants located in arid areas. In Heller towers due to the empty space inside them, in this study, instead of proposing the replacement of ACC towers, the hybrid model is proposed، where steam is Directly gonig into the ACC radiators without fan installed inside the Heller Tower، and condenses with a natural suction mechanism. The flow around the proposed model are investigated in three dimensions in two cases of no wind and no wind at 8 different  wind speeds with the assumption of incompressibility flow by the continuity, momentum, energy and turbulence equations. The hybrid tower  performance has been compared with Fars power plant cooling system and it has been shown that the proposed cooling tower has performed 25% better than the Fars cooling system in no wind condition. It has also performed better in wind conditions in different speeds except speeds above 12.5 m / s at a horizontal
array of ACCs..A vertical array of ACCs performance has been better than the horizontal array.Therefore, the hybrid model with vertical array of ACCs can be efficient to replace the cooling system of Fars power plant.


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