Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)最新文献

{"title":"Convergence analysis of cyclic Iterative Learning Control scheme","authors":"I. Shaikh, H. H. Khalili, M. Brown","doi":"10.1109/IBCAST.2012.6177517","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177517","url":null,"abstract":"Iterative Learning Control (ILC) is a learning control technique for the systems operated repeatedly. The Iterative Learning Controller learns to generate the desired set of input signals to compensate for the output tracking errors. Conventionally the performance of ILC algorithms has been based on the convergence of the output tracking error. In this paper, the convergence of the control input is investigated down to the sample-time level. Two scenarios are considered: Firstly, when the control input is updated with same initial conditions at the start of each batch/repetition/iteration/trial and secondly for varying initial conditions. The batch to batch evolution of control inputs at each sample time within a batch is formulated. Convergence of the control input signals has been based on the Eigen analysis of this relationship. This provides deeper insight about the ILC algorithms and exact factors affecting the convergence could be monitored. Limits of the learning process are clearly demonstrated as well. Performance of D-type & PD-type ILC algorithms has been investigated for a simple pendulum and further extended to bipedal locomotion. Bipedal walking robot is an interesting control problem but involves complexity being a hybrid system. It comprises of single support, impact with ground and double support phases. The non-linear impacts pose challenge since they cause non-zero initial errors for each step. For reasons of energy efficiency, passive dynamics has been chosen for compass gait model of the biped. Stable gait achieved from a fine-tuned PD controller provides the set of desired inputs for the joints of the compass gait robot. ILC learns/adapts the joint control for repetitive gaits. It represents learning a sequence of action by muscles. Due to the transfer of state error in a cyclic manner from the end of a previous step/repetition to the recent step/repetition, the convergence has to be established in joint control and state space. The steady gait is achieved for bipedal locomotion on flat surface as demonstrated through simulations.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"358 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122741870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detached eddy simulations an economical tool for CFD","authors":"M. Sohail, Yan Chao, M. Husain, R. Ullah","doi":"10.1109/IBCAST.2012.6177569","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177569","url":null,"abstract":"Flow field around high speed vehicles is very complex and difficult to simulate. The boundary layers are squeezed between shock layer and body surface. Resolution of boundary layer, shock wave and turbulent regions where the flow field has high values is difficult to capture. DNS and Large eddy simulation (LES) are very good CFD techniques but these are computationally expensive. The latter allows to generate useful solutions to transient flows, while still maintaining computationally realistic problems. Detached eddy simulation (DES) is a modification of a RANS model in which the model switches to a subgrid scale formulation in regions fine enough for LES calculations. Regions near solid body boundaries and where the turbulent length scale is less than the maximum grid dimension are assigned the RANS mode of solution. As the turbulent length scale exceeds the grid dimension, these regions are solved using the LES mode. Therefore the grid resolution is not as demanding as pure LES, thereby considerably cutting down the cost of the computation. In this research study supersonic flow is simulated at Mach 4 and different angle of attacks to calculate aerodynamics characteristics. The results are compared with experimental as well as turbulence model (K-ω SST Model). The results achieved with DES simulation have very good resolution as well as have reasonable agreement with experimental and available data at low cost.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125459517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Free convection within an eccentric annulus filled with Micropolar fluid","authors":"F. Mahfouz, H. Imtiaz","doi":"10.1109/IBCAST.2012.6177570","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177570","url":null,"abstract":"In this paper, the problem of natural convection in a circular eccentric annulus filled with Micropolar fluid has been numerically investigated using Fourier Spectral Method. The annulus inner wall is heated and maintained at constant temperature while the outer wall is cooled and kept at constant temperature. The full governing equations of momentum, angular momentum and energy have been solved to give the details of flow and thermal fields. The heat convection process in the annulus is mainly controlled by Rayleigh number Ra, Prandtl number Pr, radius ratio Rr, eccentricity e and material parameters of Micropolar fluid. The material parameters are dimensionless spin gradient viscosity λ, dimensionless micro-inertia density B and dimensionless vortex viscosity D. This study considers Ra up to 105 and the eccentricity is varied between -0.6 and +0.6 while dimensionless material parameters D of micropolar fluid is considered between 0 and 10. Both Pr and Rr are fixed at 0.7, 2.6 respectively while B and λ are assigned the value of 1. The study considers the effect of controlling parameters on flow and thermal fields with emphasis on the effect of these parameters on mean Nusselt number. The study has shown that for certain controlling parameters the heat transfer in the annulus is minimum at a certain eccentricity. The study also has shown that as parameter D increases the rate of heat transfer through the annulus decreases.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121068530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Propeller efficiency options for green ship","authors":"Salma Sherbaz, W. Duan","doi":"10.1109/IBCAST.2012.6177547","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177547","url":null,"abstract":"Environmental issues and rising fuel prices necessitate better energy-efficiency in all sectors. Shipping industry is one of the stakeholders in environmental issues. Shipping industry is responsible for 3 % of global CO2 emissions, 14-15 % of global NOX emissions and 16 % of global SOX emissions. Shipping industry also has critical role in global economy since 90 % of world trade goods are carried by ships. This trade has little or no alternate means of transportation other than ships at this point and foreseeable future. In addition, shipping is a better environmental option for transportation compared to other available means of transportation due to lowest gCO2/ton.km emissions. European Union (EU) and United Nations Framework Convention on Climate Change (UNFCCC) are pushing hard to regulate emissions in all sectors. International Maritime Organization (IMO) is working on regulating emissions from shipping with unprecedented attention and it seems clear that emissions from shipping will be regulated within few years. Furthermore, continuously rising fuel prices are also a reason to focus on new ways for better energy-effectiveness in addition to better environmental performance. Green ship concept requires exploring and implementing technologies/practices on ships to reduce emissions. Propeller efficiency is an important area to increase efficiency and reduce emissions since propellers are merely around 60 % efficient. This paper provides a comprehensive review of the propeller efficiency options to increase efficiency and reduce emissions. The paper will discuss basic concepts and principles, and popular technologies for enhancing propeller efficiency. The author will also comment on the core-issues and challenges, and scope for future development in propeller efficiency area.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128076643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of pressurization system with real-gas equation","authors":"Wang Chong, L. Guozhu","doi":"10.1109/IBCAST.2012.6177560","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177560","url":null,"abstract":"Mathematic equations considering the real-gas to simulate the pressurization system diagram for launch vehicle tanks were established with the Beattie - Bridgeman equation of state (EOS) due to the issue that the gas character cannot be accurately described by ideal-gas equation. The simulated time histories of pressure and temperature results on both gas EOSs during the starting process of a typical pressurization system were obtained. The influence of real-gas effect to the pressure and temperature were discussed. Simulation results show the effectiveness of the proposed method.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128119259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automatic resolution of crossing targets in broadband displays","authors":"K. Waqas, A. Tahir, Sadia Noreen","doi":"10.1109/IBCAST.2012.6177546","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177546","url":null,"abstract":"Tracking is an important process in sonar data processing. Tracking not only helps in keeping the track of target, but also provides necessary information to operator. This information is used for accurate bearing calculation and finally localizing target. After localization and identification of target as hostile target, it is then being fired with weapons to destroy. This makes tracking very important and pivotal in broadband displays. As long as tracking a single target is concerned, there is no known ambiguity that needs to be resolved. But in real world there are several targets present simultaneously on broadband displays. With the arrival of these several targets, several ambiguities also come in effect. One of the major ambiguities is automatic resolution of crossing targets in tracking. This resolution yields a challenge because by merely looking at the targets on broadband displays, one cannot identify difference between them. So unless targets are being identified separately, resolution of crossing target is almost impossible. Here in this research we propose a novel technique for the resolution of crossing targets in broadband displays.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"434 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132793926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HOSM control design of PEM fuel cell using super twisting algorithm","authors":"S. S. H. Rizvi, A. I. Bhatti, Q. Khan, Q. Ahmad, A. Hameed","doi":"10.1109/IBCAST.2012.6177524","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177524","url":null,"abstract":"A new scheme is tried to tackle the problems of controlling oxygen excess ratio and PEM fuel cell system output voltage stabilization. The oxygen excess ratio is controlled in the inner control loop through PID controller while the regulation of output voltage is being treated in the outer loop using super twisting algorithm of HOSM (higher order sliding mode) control. The control is applied on the nonlinear model of the PEM fuel cell system. In this scheme, the simulation results show that HOSM control provides robust performance as well as minimizes the fuel consumption. The proposed control scheme is therefore can be a step forward to make the fuel cell technology inexpensive with optimal robust performance.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127793029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transient heat transfer analysis in a two-pass smooth channel using CFD code","authors":"M. A. Rahi, Imdad Ali Bugti","doi":"10.1109/IBCAST.2012.6177552","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177552","url":null,"abstract":"In this paper transient heat transfer analysis in a smooth two-pass square channel is done using numerical techniques. This study is carried out in a 3D model of the two pass channel by assuming 1-D heat transfer in span-wise direction. The detailed Nusselt number distributions are investigated for a two pass smooth channel in the first pass, before the 1800 turn section and in the second pass. The numerical results are compared with the experimental data, and are found to be in good agreement. The detailed distributions and numerical post processing result provide a clear understanding of the secondary flows by the sharp turn. This study was limited to two Reynolds numbers of 30,000 and 60,000.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134310795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Klopfenstein tapered 2–18 GHz microstrip balun","authors":"Syed Ahsaan Panjtan Rizvi, Raja Asad Ajmal Khan","doi":"10.1109/IBCAST.2012.6177579","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177579","url":null,"abstract":"Tapered microstrip Balun is used as an impedance transformer network in feeding sections of spiral antennas as it provides impedance transformation over a large range of frequency and also serves the purpose of conversion of single ended port to a symmetric port. The conversion from unbalanced to balanced line relies on a gradual change of cross section of the line. This paper presents a 2-18 GHz microstrip Balun that uses the Klopfenstein equations for the taper. The Balun structure was first simulated in Ansoft HFSS and then fabricated; there was a close match between the simulated and measured results.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"35 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114129771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Analysis of flow in cavities of labyrinth seals","authors":"S. Afzal, S. M. Hassan, M. Sohaib, M. Rafique","doi":"10.1109/IBCAST.2012.6177555","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177555","url":null,"abstract":"Objective of this study is to analyze the performance of a straight sealing labyrinth in gas turbine engines in static as well as dynamic conditions. The study contains the effect of Reynolds number and ratio of tooth width to tip gap (tw/C) on the performance of straight sealing labyrinth. The analysis was carried out for different pressure ratios (PR) and different rotational speeds (RPM). The results are in good agreement with the available experimental results.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125095162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}