Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)最新文献_第8页

Effect of large amplitude pitch-up motions on un-commanded roll behavior of low swept wings-slender body model 大振幅俯仰运动对低后掠翼细长体模型非命令滚转行为的影响

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177558

T. A. Khan, Xue-ying Deng

{"title":"Effect of large amplitude pitch-up motions on un-commanded roll behavior of low swept wings-slender body model","authors":"T. A. Khan, Xue-ying Deng","doi":"10.1109/IBCAST.2012.6177558","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177558","url":null,"abstract":"Desire for super maneuverability and agility for modern air vehicles has resulted in high angles of attack flights. Different dynamic instability phenomenon may arise at high angles of attack. Wing rock, which is self excited limit cycle oscillations in roll mainly, is amongst one of these. Experiments have been carried out at sub-critical Reynolds number to investigate un-commanded free-to-roll (FTR) motions induced by forebody complex flow on a 30° swept back non-slender wings-slender body-model. Experimental investigations of FTR motions are firstly conducted for static angles of attack (0° to 90°) to understand the basic flow and aerodynamics mechanisms followed by the effects of large amplitude pitch-up motions at variable rates on these un-commanded roll motions. It has been observed that asymmetric forebody vortices (AFV) dominate and control the roll motion of the model for angles of attack >; 26°. For the dynamic (pitch-up) case it has been observed that roll amplitude decreases and lag increases with increase in pitch-up rate. Increase in windward and leeward surface pressures with increase in pitch-up rate is observed. This increase in surface pressures is asymmetric on the wings leeward side in AFV region, angle of attack >; 26°. Decrease in roll amplitude, increase in damping or restoring moment provided by the lower surface and increase in normal force and side force coefficients are attributed to these changes in the surface pressures due to the pitch-up effect. Roll behavior for non-dimensional pitch-up rate ≥ 1×10-2 is characterized by sinusoidal type curve, absence of roll divergence and no significant roll contribution from the wings flow.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"9 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":"122179717","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}

引用次数: 0

Cascaded face recognition system via sparse representation 基于稀疏表示的级联人脸识别系统

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177525

A. Baig, R. Nawaz

引用次数: 2

ISAR imaging of rotating targets using Matrix Pencil back-Projection method 基于矩阵铅笔反投影法的旋转目标ISAR成像

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177577

S. Qadir, Yangyu Fan, Wang Bao-ping, M. Shabbir, F. Arneeb

引用次数: 4

Probability density function computations of a strongly swirling flame 强旋转火焰的概率密度函数计算

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177566

M. Usman, S. Malik, M. Rafique

引用次数: 1

Numerical study of conjugate heat transfer within a bottom heated cylindrical enclosure 底部受热圆柱壳体内共轭传热的数值研究

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177556

A. Malik, M. Alvi, S. Khushnood, F. Mahfouz, M. Ghauri, A. Shah

引用次数: 1

High performance compact microwave filters for space applications 用于空间应用的高性能紧凑型微波滤波器

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177582

J. Zaidi, U. Naeem, M. A. Shah

引用次数: 0

Design & development of a 32 elements X-band Phased Array antenna for airborne & Space borne SAR payloads 设计和开发用于机载和空载SAR有效载荷的32元x波段相控阵天线

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177576

A. S. Shafaat Ali, M. Raza, M. A. Shah

{"title":"Design & development of a 32 elements X-band Phased Array antenna for airborne & Space borne SAR payloads","authors":"A. S. Shafaat Ali, M. Raza, M. A. Shah","doi":"10.1109/IBCAST.2012.6177576","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177576","url":null,"abstract":"Air Borne & Space Borne SAR Payloads are used now a days in variety of missions for different applications. Onboard SAR payload consists of a digital signal processing & data storage unit, a transceiver and an antenna unit. Onboard antenna is a vital unit of a communication system and design of antenna becomes much more critical and complex once electronic beam steering is an essential requirement. Usually for SAR applications, electronically steerable high gain antennas are required to support different operating modes. In this paper, design of 32 elements X-band Phased Array is discussed along with its simulation and measurement results. Design antenna is based on microstrip technology and orientation of feeding mechanism to a certain group of elements is such that it provides circular polarization both across range/azimuth. Electronically steering is possible by changing the phase at the inputs of the antenna ports and different possible steering scenarios are discussed in this paper. An advanced EM simulation software is being used for design and simulation purpose. Simulated results provide a gain of approximately 20 dB with a VSWR <; 2 at desired frequency range in the band. Axial ratio of <; 3 is targeted and achieved in the desired frequency range.","PeriodicalId":251584,"journal":{"name":"Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST)","volume":"30 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":"125562268","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}

引用次数: 6

Spherical embedded antenna for conformal applications 用于共形应用的球形嵌入式天线

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177573

A. Mueed, Jiadong Xu, Y. Shangbin

{"title":"Spherical embedded antenna for conformal applications","authors":"A. Mueed, Jiadong Xu, Y. Shangbin","doi":"10.1109/IBCAST.2012.6177573","DOIUrl":"https://doi.org/10.1109/IBCAST.2012.6177573","url":null,"abstract":"Use of planar antenna for conformal applications is of great engineering utilization; however antenna embedding into conformal shapes needs careful analysis. The cavity-backed proximity coupled microstrip patch antenna for spherical conformal application is analyzed. Dielectric and metallic material is used for the sphere. Coax fed antenna is used for embedding for conformal application. A dielectric cover is placed on top of the surface of the antenna to shield the patch and make the spherical surface continuous. Two types of spherical cuts are used with radii of 2λ and 5λ and thickness of 0.508 mm and 7 mm. Simulation results including vswr, radiation pattern and gain are provided. The parametric study including the effect of material, thickness, radius and dielectric cover is also discussed for the design. The results indicate that the bandwidth of coax fed antenna exceeds 30% at X- band and the impedance of the antenna is not sensitive to the spherical radius, however the radiation pattern is affected for different thickness and extent of cut of sphere. The radiation pattern is more stable in case of dielectric sphere with reduced thickness as compared to the metallic sphere with increased thickness, irrespective of extent of sphere cut. The dielectric sphere with increased thickness and metallic sphere with reduced thickness deteriorate the radiation pattern by introducing higher back and side lobes. The effect of dielectric cover is to shift the frequency band towards lower frequencies. Higher gain is observed for metallic spheres. Such an embedded antenna has the potential to be easily used for platform mounted applications like UAV, Missile or satellites.","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":"128849319","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}

引用次数: 5

Stochastic geometry of thinned nodes in ad hoc networks 自组织网络中稀疏节点的随机几何

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 2012-04-03 DOI: 10.1109/IBCAST.2012.6177594

A. Ali, A. Hasan

引用次数: 3

Cooperative communication in 3-UAVs: Performance analysis with BICM transmission 3-无人机协同通信:BICM传输的性能分析

Proceedings of 2012 9th International Bhurban Conference on Applied Sciences & Technology (IBCAST) Pub Date : 1900-01-01 DOI: 10.1109/IBCAST.2012.6177536

S. M. Shah, R. Samar

引用次数: 1