Publications

R I C

Click here to edit subtitle

2016  (Vol. 7, No. 1)

Simulation and Optimization of Vacuum Tube Solar Collector Water Heating System in Iran


Majid Azimi, Seyed Sajad Mirjavadi, Ahmadreza Mohammadkarim

Corresponding Author: Ahmadreza Mohammadkarim

Vol. 07 (01), 2016, 001-019

Abstract

The evacuated tube solar collectors with the free circulation water between the tubes and horizontal tank above it are economically cheaper than heat pipes collector systems. This type of solar system is widely used in the world. This paper is dedicated to simulating the vacuum tube solar water heating system with natural circulation water between the tubes under the different climatic conditions in Iran with TRNSYS16 software. The most important component diagram used in the simulation with the TRNSYS16 is Type71 for vacuum tube collector. Five nodes are stratified at different heights in horizontal tank for increasing the water in higher height of the tank. Initially we assume arbitrarily consecutive ten days in each twelve-months of the year. The values of the daily, monthly and yearly useful energy gain, efficiency and solar fraction are obtained. Also values of the outlet water temperature from each evacuated tube, ambient temperature and solar radiation are extracted.  In order to improve the performance of the evacuated tube solar water heater, optimization of the efficiency this system is expressed by genetic algorithm Toolbox in MATLAB software.

Keywords: Vacuum Tube Solar Collector, TRNSYS, Optimization, Efficiency

Submitted
 Accepted
28 October 2015
05 December 2015
 

Error Compensation for Continuous Path Operation of 3-RRR Planar Parallel Manipulator with Clearance in the Joints


Mohammad Farajtabar, Hamid M. Daniali, Seyyed M. Varedi

Corresponding Author: Mohammad Farajtabar

Vol. 07 (01), 2016, 020-033

Abstract

In this paper, we study continuous path operation of a 3-RRR planar parallel manipulator whose joints have clearance. During continuous path operation end-effector must go through a predefined path. However, clearance introduces an additional uncontrollable degree of freedom to the manipulator. Therefore it causes error and should not be neglected in a successful path operation. In this paper, inverse and direct kinematics- with and without considering clearances, of the manipulator have been utilized. The direct kinematics in the presence of clearance is complicated and has no analytical solution. Therefore, a Neural Network is used to tackle this problem. The clearances are modelled as mass-less virtual links whose angular displacement are obtained from dynamic analysis of the manipulator. We have shown that the errors in the path can be efficiently compensated by appropriate modifications of the inputs for both vertical and horizontal planes. Perhaps surprisingly, the flexibility and generality of the proposed method makes it applicable to any parallel manipulator with revolute joints by just modifying the actuator inputs and without any changes in the design of manipulator.

Keywords: Parallel manipulator, continuous path operation, clearance, dynamics, kinematics

Submitted
 Accepted
29 October 2015
25 December 2015
 

Amr M. Ibrahim, Noha M. Bastawy, Hossam E. Talaat

Corresponding Author: Amr M. Ibrahim

Vol. 07 (01), 2016, 034-049

Abstract

Unified Power Flow Controller (UPFC) is regarded as the most generalized version of Flexible AC Transmission Systems (FACTS) devices. UPFC serves to control line impedance, voltage and phase angle at the same time. However, this in turn introduces problems in conventional distance protection. This paper proposes an approach based on Feed-Forward Neural Network (FNN) using the Total Least Square-Estimation of Signal Parameters via Rotational Invariance Technique (TLS-ESPRIT) for fault type classification and faulted phase selection to be used in the protection of transmission lines employing Unified Power Flow Controller (UPFC). The required features for the proposed algorithm are extracted from transient currents and voltages waveforms measured at the relaying point using TLS-ESPRIT. System simulation and test results which are presented and analyzed in this paper indicate the feasibility of using FNN with TLS-ESPRIT in the protection of transmission line compensated with UPFC. In this paper, the proposed approach based on FNN is compared with two approaches one of them is based on Recurrent Neural Network (RNN) and the other one is based on Gaussian Process (GP).

Keywords: Feed-Forward Neural Network (FNN), Distance protection, Fault classification, Recurrent Neural Network (RNN), Gaussian Process (GP), Total Least Square-Estimation of Signal Parameters via Rotational Invariance Technique (TLS-ESPRIT), Unified Power Flow Controller (UPFC)

Submitted
 Accepted
06 January 2016
11 February 2016
 
A. L. Sivakumar, G. Chandrasekaran

Corresponding Author: A. L. Sivakumar

Vol. 07 (01), 2016, 050-071

Abstract

The utilization of structural control systems for alleviating the vibrating systems which are the major causes of noise problems, passenger discomforts, and mechanical failures in aerospace, automotive, and civil structures has become a standard technology and there are still several research approaches for development the effectiveness of these methods. The aim of this article is to review current state-of-the-art of modeling procedure for ground vehicle suspensions, building structures, plates and shells and classic and modern controller algorithms have been used for active vibration and noise control systems. A brief description of each of these main groups and their subgroups with their corresponding advantages and disadvantages will be provided.

Keywords: structural control system, vibration suppression, active vibration control, smart structures, vibration control techniques

Submitted
 Accepted
03 February 2016
 01 March 2016
 

Majid Azimi, Seyed Sajad Mirjavadi, Mohammadreza Sedighi

Corresponding Author: Seyed Sajad Mirjavadi

Vol. 07 (01), 2016, 072-082

Abstract

Liquid cooling garments (LCGs) show several advantages over other types of personal cooling garments. Liquid-filled tubes extract excessive heat from the body. Water is cooled by passing through a block which is on contact with cold side of a thermoelectric.  The purpose of this study is to parametrically analyze the thermal performance of a water block in the cooling system. The conjugated heat transfer has been numerically studied. Results show that temperature difference versus number of fins and the block dimensions has increasing behavior. With inlet velocity magnitude, heat transfer performance decreases. Thermal conductivity of the block does not have considerable effect on the cooling system performance. Finally, ethylene glycol rises the temperature difference versus water as a coolant.

Keywords: Water Block, Heat Transfer, Liquid Cooling System, CFD

Submitted
 Accepted
11 February 2016
 26 March 2016
 

Bo Wang, Jungsuk Song, Hong Wang, Ping Cheng, Guifu Ding, Zhuoqing Yang

Corresponding Author: Guifu Ding

Vol. 07 (01), 2016, 083-090

Abstract

In this paper, a low-cost acid cyanide-free silver plating bath has been developed and optimized to electroplate the silver (Ag) film with a high reflectivity and glossiness as the reflective layer for LED package. The effects of the bath composition, the additive and the pH value on the stability of plating bath have been investigated by orthogonal experiment. The optimal composition for thiosulfate bath is 30~42.5 g/L AgNO3, 200~250 g/L Na2S2O3, and 40~45 g/L K2S2O5 with a pH value of 5~6. By trying different additives and optimizing the composition, the mirror-bright Ag film with good reflectivity and smooth surface has been successfully electroplated. The brightness, reflectivity and glossiness of the electroplated Ag film have been characterized, which indicates that the electroplated Ag film is promising to act as the reflective layer for LED package.

Keywords: Acid cyanide-free Ag electroplating; Ag reflective film; LED

Submitted
 Accepted
14 January 2016
 29 February 2016