Design Optimization and Analysis of Thermoacoustic Refrigerators

2020 ◽  
Vol 28 (03) ◽  
pp. 2050020
Author(s):  
B. G. Prashantha ◽  
D. R. Swamy ◽  
Bhimasen Soragaon ◽  
T. S. Nanjundeswaraswamy
Keyword(s):  
Design Optimization ◽  
Noble Gases ◽  
Cooling Power ◽  
Dry Air ◽  
Novel Technology ◽  
Pure Helium ◽  
Simulation Results ◽  
Thermoacoustic Refrigeration ◽  
Theoretical Results ◽  
Thermoacoustic Refrigerators

Thermoacoustic refrigeration, a novel technology, uses eco-friendly gases like helium, air or the mixture of noble gases as working substances in the absence of moving parts. The design, optimization and analysis of thermoacoustic refrigerators using helium and air as oscillating gases are discussed. Pure helium is chosen since it is proven as the best and economical working gas compared to the alternate pure or the mixture of noble gases. Air is chosen since it is abundant in nature and the least cost of the pressurized dry air cylinders. The design optimization strategies discussed in this paper serve as a guide for aspiring researchers in the design and development of thermoacoustic coolers. Cooling power as a function of stack diameter is discussed. Theoretical results of the optimized coolers are compared with DeltaEC simulation results for validation and are in agreement with each other.

Effect of Stack Spacing on the Performance of Thermoacoustic Refrigerators Using Helium and Air as Working Substances

2019 ◽  
Vol 27 (02) ◽  
pp. 1950016 ◽  
Author(s):  
B. G. Prashantha ◽  
S. Seetharamu ◽  
G. S. V. L. Narasimham ◽  
M. R. Praveen Kumar
Keyword(s):  
Heat Exchanger ◽  
Penetration Depth ◽  
Power Density ◽  
Cooling Power ◽  
Quarter Wavelength ◽  
Thermal Penetration Depth ◽  
Theoretical Results ◽  
Theoretical Performance ◽  
Thermoacoustic Refrigerators

This paper deals with the design of thermoacoustic refrigerators using linear thermoacoustic theory. The refrigerator components are designed at 3% drive ratio by considering the practical limitations of providing sufficient spacing for attaching the loudspeaker to the resonator tube and accommodating instrumentation. The effects of spiral stack spacing in terms of thermal penetration depth on the theoretical performance of refrigerator using helium and air as working substances are discussed. The quarter-wavelength resonator designs with taper and divergent section terminated with hemispherical end are optimized with helium and air for better performance. Theoretical results are validated with DeltaEC software results and are in agreement with each other. Helium shows better performance compared to air but lacks power density. The DeltaEC predicts COP 0.514 at the cold heat exchanger temperature of [Formula: see text]C with helium compared to air (COP 0.616 at [Formula: see text]C) for the 50[Formula: see text]W cooling power 100[Formula: see text]mm diameter quarter-wavelength resonator designs.

scholarly journals A Convergent Collocation Approach for Generalized Fractional Integro-Differential Equations Using Jacobi Poly-Fractonomials

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 979
Author(s):  
Sandeep Kumar ◽  
Rajesh K. Pandey ◽  
H. M. Srivastava ◽  
G. N. Singh
Keyword(s):  
Differential Equation ◽  
Fractional Derivative ◽  
Collocation Method ◽  
Caputo Fractional Derivative ◽  
Fractional Derivatives ◽  
Special Cases ◽  
Collocation Approach ◽  
Linear And Nonlinear ◽  
Simulation Results ◽  
Theoretical Results

In this paper, we present a convergent collocation method with which to find the numerical solution of a generalized fractional integro-differential equation (GFIDE). The presented approach is based on the collocation method using Jacobi poly-fractonomials. The GFIDE is defined in terms of the B-operator introduced recently, and it reduces to Caputo fractional derivative and other fractional derivatives in special cases. The convergence and error analysis of the proposed method are also established. Linear and nonlinear cases of the considered GFIDEs are numerically solved and simulation results are presented to validate the theoretical results.

scholarly journals Multicell Power Supplies for Improved Energy Efficiency in the Information and Communications Technology Infrastructures

2021 ◽  
Author(s):  
Michael Chrysostomou ◽  
Nicholas Christofides ◽  
Stelios Ioannou ◽  
Alexis Polycarpou
Keyword(s):  
Energy Demand ◽  
Information And Communications Technology ◽  
Power Supplies ◽  
Communications Technology ◽  
Cell Structures ◽  
Full Power ◽  
Overall Efficiency ◽  
Simulation Results ◽  
The Individual ◽  
Theoretical Results

The rapid growth of the Information and Communications Technology (ICT) sector requires additional infrastructure, such as more micro-datacenters and telecom stations, to support the higher internet speeds and low latency requirements of 5G net-works. The increased power requirements of the new ICT technologies necessitate the proposal of new power supplies in an attempt to retain the increase in energy demand and running costs. This work provides an in-depth theoretical analysis on the losses of the individual stages of commercially available PSU and proposes a new multicell PSU, Buck-PFC converter, which offers a higher overall efficiency at varying load levels. The theoretical results are verified using simulation results, via PSIM Thermal Module, and using experimental data. The results indicate that multi-cell structures can improve the overall PSU ef-ficiency by 1.2% at 50% rated power and more than 2.1% at full power. Finally, taking into consideration the economic implica-tions of this study, it is shown that the proposed multicell structure may increase the PSU costs by 10.78% but the payback pe-riod is in the order of just 3.3 years.

scholarly journals Simulation and Measurement Studies of The Vdes System’s Terrestrial Component

2019 ◽  
Vol 26 (1) ◽  
pp. 95-106 ◽  
Author(s):  
Krzysztof Bronk ◽  
Patryk Koncicki ◽  
Adam Lipka ◽  
Dominik Rutkowski ◽  
Błażej Wereszko
Keyword(s):  
Data Transmission ◽  
Data Exchange ◽  
Technical Information ◽  
Theoretical Data ◽  
Current Version ◽  
Coding Gain ◽  
Exchange System ◽  
Measurement Results ◽  
Simulation Results ◽  
Theoretical Results

Abstract In the paper, the measurement and simulation results of the VDES (VHF Data Exchange System) terrestrial component are discussed. It is anticipated that VDES will be one of the major solutions for maritime communications in the VHF band and its performance will be sufficient to fulfill the requirements of the e-navigation applications. The process of the VDES standardization (ITU R, IALA) has not been officially completed yet, but substantial amount of technical information about the future system’s terrestrial component (VDE-TER) is already available. The paper is divided into three general parts: (a) theoretical presentation of the system’s physical layer and the radio channels applicable to VDES, (b) simulation results (BER, BLER, channel delay between two propagation paths and its influence on bit rates) and (c) measurement results (useful ranges, BER). It turned out that in real maritime conditions, the VDES system can offer ranges between 25 and 38 km for the configurations assumed during the measurement campaign. Those results are generally compliant with the theoretical data in the line-of-sight conditions. In the NLOS scenarios, where fading becomes the dominant phenomenon, the discrepancies between the measurements and the theoretical results were more significant. The obtained results confirmed that VDES provides a large coding gain, which significantly improves the performance of data transmission and increases the bit rate compared to the existing maritime radiocommunication solutions. It should be noted that the results presented in the article were used by the IALA while developing the current version of the VDES specification.

Computation of Madalines' Sensitivity to Input and Weight Perturbations

2006 ◽  
Vol 18 (11) ◽  
pp. 2854-2877 ◽  
Author(s):  
Yingfeng Wang ◽  
Xiaoqin Zeng ◽  
Daniel So Yeung ◽  
Zhihang Peng
Keyword(s):  
Probability Theory ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
Analytical Formula ◽  
Single Neurons ◽  
Important Measure ◽  
Simulation Results ◽  
Theoretical Results ◽  
Good Agreement

The sensitivity of a neural network's output to its input and weight perturbations is an important measure for evaluating the network's performance. In this letter, we propose an approach to quantify the sensitivity of Madalines. The sensitivity is defined as the probability of output deviation due to input and weight perturbations with respect to overall input patterns. Based on the structural characteristics of Madalines, a bottomup strategy is followed, along which the sensitivity of single neurons, that is, Adalines, is considered first and then the sensitivity of the entire Madaline network. Bymeans of probability theory, an analytical formula is derived for the calculation of Adalines' sensitivity, and an algorithm is designed for the computation of Madalines' sensitivity. Computer simulations are run to verify the effectiveness of the formula and algorithm. The simulation results are in good agreement with the theoretical results.

Resonator Optimization and Studying the Effect of Drive Ratio on the Theoretical Performance of a 10-W Cooling Power Thermoacoustic Refrigerator

2015 ◽  
Vol 23 (03) ◽  
pp. 1550020 ◽  
Author(s):  
B. G. Prashantha ◽  
M. S. Govinde Gowda ◽  
S. Seetharamu ◽  
G. S. V. L. Narasimham
Keyword(s):  
Dynamic Pressure ◽  
Optimization Procedure ◽  
Cooling Power ◽  
Pressure Amplitude ◽  
Performance Simulation ◽  
Resonator Design ◽  
Working Principle ◽  
Simulation Results ◽  
Theoretical Performance ◽  
Thermoacoustic Refrigerator

This paper deals with the basic insight of thermoacoustic refrigeration concepts, and the working principle, history and the role of linear thermoacoustic theory in designing a thermoacoustic refrigerator system are discussed. Resonator design optimization procedure for a 10W cooling power thermoacoustic refrigerators is discussed. The optimized resonator designs proposed in this paper are found to be efficient compared to published resonator designs. The effects of drive ratio on the theoretical performance by varying dynamic pressure amplitude from 0.2 bar to 0.4 bar in the steps of 0.05 bar on the optimized resonator designs are discussed. Performance simulation results for the optimized resonator designs using DeltaEC software are discussed. Simulation results are in agreement with theoretical results.

Benchmark Investigation of Dynamics Models for Design Optimization of Articulated Heavy Vehicles

2013 ◽  
Author(s):  
Md Manjurul Islam ◽  
Yuping He
Keyword(s):  
Design Optimization ◽  
Software Package ◽  
Eigenvalue Analysis ◽  
Heavy Vehicle ◽  
Tire Model ◽  
Heavy Vehicles ◽  
Plane Model ◽  
Motion Modes ◽  
Simulation Results ◽  
Dynamics Models

This paper represents validation of yaw plane and yaw-roll models of a tractor/semitrailer combination with TruckSim software package. A linear 3 degree-of-freedom (DOF) yaw-plane model and a linear 5 DOF yaw-roll model of tractor/semitrailer have been generated, compared and evaluated. This paper investigates the applicability of vehicle models with linear tire model. The models of the articulated heavy vehicle (AHV) yield excellent simulation results which are validated by comparing the simulation results obtained from TruckSim. This paper also includes eigenvalue analysis of the models to estimate their unstable motion modes. Benchmark comparison of the models has been performed to investigate the fidelity, complexity and applicability.

scholarly journals Consensus of Fractional-Order Multiagent Systems with Nonuniform Time Delays

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jun Liu ◽  
Kaiyu Qin ◽  
Wei Chen ◽  
Ping Li ◽  
Mengji Shi
Keyword(s):  
Multiagent Systems ◽  
Fractional Order ◽  
Time Delays ◽  
External Environment ◽  
Domain Theory ◽  
Dynamical Model ◽  
Integer Order ◽  
The Laplace Transform ◽  
Simulation Results ◽  
Theoretical Results

Due to the complex external environment, many multiagent systems cannot be precisely described or even cannot be described by an integer-order dynamical model and can only be described by a fractional-order dynamical model. In this paper, consensus problems are investigated for two types of fractional-order multiagent systems (FOMASs) with nonuniform time delays: FOMAS with symmetric time delays and undirected topology and FOMAS with asymmetric time delays and directed topology. Employing the Laplace transform and the frequency-domain theory, two delay margins are obtained to guarantee the consensus for the two types of FOMAS, respectively. These results are also suitable for the integer-order dynamical model. Finally, simulation results are provided to illustrate the effectiveness of our theoretical results.

Forward Kinematics Simulation for a Surgical Robot Using CATIA 5

2015 ◽  
Vol 22 ◽  
pp. 21-28
Author(s):  
Shao Gang Liu ◽  
Farah Edris
Keyword(s):  
Minimally Invasive Surgery ◽  
Theoretical Calculations ◽  
Surgical Robot ◽  
Forward Kinematics ◽  
Kinematic Simulation ◽  
Kinematics Simulation ◽  
Robot Tracking ◽  
Simulation Results ◽  
Forward Kinematic ◽  
Theoretical Results

Forward Kinematic simulation of a 6 DOF surgical robot tracking a path through the constraint of the Remote Center of Motion point (RCM) is developed in this paper. Theoretical calculations of the forward kinematics are analyzed by solving the configuration kinematic equations of the robot. CAD prototype of the surgical robot and the patient are created using CATIA5 part and assembly tools. The theoretical results are validated through a Kinematic simulation of CATIA kinematics. The simulation results confirm the usefulness of the six revolute joint robots in minimally invasive surgery (MIS) and the efficiency of using the power full CATIA5 software to simulate surgical robot, and checking the robot mechanism capability of doing surgical procedures.

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