检索结果-南通市图书馆

Journal of Central South University 2015年第6期22卷 2376-2384页

作者： ABBAS Zaheer masood Tahmina OLANREWAJU Philip Oladapo Department of Mathematics The Islamia University of Bahawalpur Department of Mathematical Sciences Oduduwa University

An analysis was made to study the steady momentum and heat transfer characteristics of a viscous electrically conducting fluid near a stagnation point due to a stretching/shrinking sheet in the presence of a transverse magnetic field and generalized slip condition. Two flow problems corresponding to the planar and axisymmetric stretching/shrinking sheet were considered. By means of similarity transformations, the obtained resultant nonlinear ordinary differential equations were solved numerically using a shooting method for dual solutions of velocity and temperature profiles. Some important physical features of the flow and heat transfer in terms of the fluid velocity, the temperature distribution, the skin friction coefficient and the local Nusselt number for various values of the controlling governing parameters like velocity slip parameter, critical shear rate, magnetic field, ratio of stretching/shrinking rate to external flow rate and Prandtl number were analyzed and discussed. An increase of the critical shear rate decreases the fluid velocity whereas the local Nusselt number increases. The comparison of the present numerical results with the existing literature in a limiting case is given and found to be in an excellent agreement.

关键词：速度滑移收缩率拉伸流动广义 MHD 非线性常微分方程换热

Symmetry solutions of a nonlinear elastic wave equation with third-order anharmonic corrections

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2009年第8期30卷 1017-1026页

作者： M.Tahir Mustafa Khalid masood Department of Mathematics and Statistics King Fahd University of Petroleum and MineralsDhahran 31261 Saudi Arabia Department of Mathematics Hafr Al-Batin Community College King Fahd University of Petroleum and MineralsP. O. Box 5087 Dhahran 31261 Saudi Arabia

Lie symmetry method is applied to analyze a nonlinear elastic wave equation for longitudinal deformations with third-order anharmonic corrections to the elastic energy. Symmetry algebra is found and reductions to second-order ordinary differential equations （ODEs） are obtained through invariance under different symmetries. The reduced ODEs are further analyzed to obtain several exact solutions in an explicit form. It was observed in the literature that anharmonic corrections generally lead to solutions with time-dependent singularities in finite times singularities, we also obtain solutions which Along with solutions with time-dependent do not exhibit time-dependent singularities.

关键词： group invariant solutions Lie symmetries nonlinear elasticity equations partial differential equations

Modeling, analysis, and optimization of dimensional accuracy of FDM-fabricated parts using definitive screening design and deep learning feedforward artificial neural network

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2021年第1期9卷 115-129页

作者： Omar Ahmed Mohamed Syed Hasan masood Jahar Lal Bhowmik School of Engineering Deakin UniversityGeelongAustralia Department of Mechanical Engineering Higher Institute of Engineering TechnologyBani WalidLibya Department of Mechanical and Product Design Engineering Swinburne University of TechnologyHawthornVIC 3122Australia Department of Health Science and Biostatistics Swinburne University of TechnologyHawthornVIC 3122Australia

Additive manufacturing(AM)technologies such as fused deposition modeling(FDM)rely on the quality of manufactured products and the process ***,the dimensional accuracy and stability of any AM process is essential for ensuring that customer specifications are satisfied at the highest standard,and variations are controlled without significantly affecting the functioning of processes,machines,and product *** study aims to investigate the effects of FDM fabrication conditions on the dimensional accuracy of cylindrical *** this study,a new class of experimental design techniques for integrated second-order definitive screening design(DSD)and an artificial neural network(ANN)are proposed for designing experiments to evaluate and predict the effects of six important operating *** determining the optimum fabrication conditions to obtain better dimensional accuracies for cylindrical parts,the time consumption and number of complex experiments are reduced considerably in this *** optimum fabrication conditions generated through a second-order DSD are verified with experimental *** results indicate that the slice thickness,part print direction,and number of perimeters significantly affect the percentage of length difference,whereas the percentage of diameter difference is significantly affected by the raster-to-raster air gap,bead width,number of perimeters,and part print ***,the results demonstrate that a second-order DSD integrated with an ANN is a more attractive and promising methodology for AM applications.

关键词： Artificial neural network(ANN) OptimizationDefinitive screening design(DSD) Analysis of variance(ANOVA) Fused deposition modeling(FDM) Dimensional accuracy

Effect of controlled rolling on the martensitic hardenability of dual phase steel

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 165-169页

作者： Mohammad Ajmal masood Ahmed Tindyala Ron Priestner Department of Metallurgical & Materials Engineering University of Engineering & TechnologyG.T. Road Lahore-54890Pakistan Manchester Materials Science Center University of Manchester Institute of Science and Technology (UMIST)ManchesterM1 7HSUK

The C-Mn and C-Mn-Nb steels were thermo-mechanically processed to develop dual phase steel and to study the effect of controlled rolling on the martensitic hardenability of austenite. The steel specimens were intercritically annealed at 790℃, rolled at that temperature to the reductions of 10%, 23%, and 47% and immediately cooled at different rates. Quantitative metallography was used to construct the microstructure map, which illustrated that increasing deformation progressively reduced the proportion of new ferrite formed at all cooling rates and increased the amount of martensite at fast and intermediate rates. The martensitic hardenability of austenite remaining after all the rolling reductions was plotted as a function of cooling rates. It was observed that for the austenite-martensite conversion efficiencies greater than about 25%, controlled rolling increased the martensitic hardenability of austenite.

关键词： controlled rolling dual phase steel intercritical annealing hardenability phase transformation

Development of multi-physics numerical simulation model to investigate thermo-mechanical fatigue crack propagation in an autofrettaged gun barrel

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2021年第5期17卷 1579-1591页

作者： Naveed Hussain Faisal Qayyum Riffat Asim Pasha masood Shah Department of Mechanical Engineering University of Engineering and TechnologyTaxilaPakistan Institut für Metallformung Technische Universitat BeragakademieFreibergGermany

In this research,a detailed multi-physics study has been carried out by numerically simulating a solid fractured gun barrel for 20 thermo-mechanical *** numerical model is based on thermal effects,mechanical stress fields and fatigue crack ***-plastic material data of modified AISI 4340 at temperatures ranging from 25 to 1200℃and at strain rates of 4,16,32 and 48 s^(-1) was acquired from high-temperature compression *** was used as material property data in the simulation *** boundary conditions applied are kept similar to the working gun barrel during continuous firing.A methodology has been provided to define thermo-mechanically active surface-to-surface type interface between the crack faces for a better approximation of stresses at the crack *** of results from non-autofrettaged and autofrettaged simulation models provide useful information about the evolution of strains and stresses in the barrel at different points under combined thermo-mechanical loading cycles in both *** effect of thermal fatigue under already induced compressive yield due to autofrettage and the progressive degradation of the accumulated stresses due to thermo-mechanical cyclic loads on the internal surface of the gun barrel(mimicking the continuous firing scenario)has been *** between energy release rate at tips of varying crack lengths due to cyclic thermo-mechanical loading in the non-autofrettaged and autofrettaged gun has been carried out.

关键词： Steel Autofrettage Gun barrel Crack propagation Thermo-mechanical fatigue Numerical simulation Residual stress dissipation

在线全文

学校读者我要写书评

暂无评论

人手自动艾灸仪的研究与设计

人手自动艾灸仪的研究与设计

作者： Danish masood 山东大学

学位级别：硕士

针灸疗法在世界各地广泛应用。穴位刺激对康复和预防治疗具有重要意义。艾灸是一种穴位疗法,主要由实践者依靠人工定位和定位穴位来进行,由于人为错误,导致准确性的差异。事实证明,使用电子设备自动检测穴位的发展有助于从业者准确定位... 详细信息

针灸疗法在世界各地广泛应用。穴位刺激对康复和预防治疗具有重要意义。艾灸是一种穴位疗法,主要由实践者依靠人工定位和定位穴位来进行,由于人为错误,导致准确性的差异。事实证明,使用电子设备自动检测穴位的发展有助于从业者准确定位穴位。但是仍然有很大的需要使穴位的定位完全自动化。过去,计算机视觉技术被用于检测身体不同部位的穴位。事实证明,深度学习技术在一定程度上解决了使用图像处理和神经网络进行自主检测的问题。但是目前的方法缺乏基于深度的定位,因此局限于二维定位。为了开发一个能够检测穴位精确定位并执行机器人控制的刺激的系统,必须考虑穴位的三维坐标信息。本研究提出了一种基于RGB-CNN和深度CNN融合的三维穴位定位新方法,提取人手的特征和地标针灸目前在世界各地均有广泛应用,其中穴位刺激对于康复和预防治疗具有重要意义。艾灸就是一种穴位疗法,主要由操作者依靠人工判断和穴位定位来进行,但是由于存在人为主观性的错误,可能存在准确性误差的问题。事实证明,自动检测穴位电子设备的发展有助于从业者准确定位穴位,但是仍然距离完全实现自动化具有很大差距。过去,计算机视觉技术被用于检测身体不同部位的穴位。事实证明,深度学习技术在一定程度上解决了使用图像处理和神经网络进行自主检测的问题。但是目前的方法缺乏基于深度的定位,局限于二维定位。为能开发一个检测穴位精确定位并且能够执行机器人控制刺激穴位的系统,必须考虑穴位的三维坐标信息。本研究提出了一种基于颜色卷积神经网络和深度卷积神经网络融合的三维穴位定位新方法,提取人手的特征和标志点,从而计算出穴位的三维坐标信息,指导机械手。总体研究成果如下:首先,使用棋盘格模式对三维视觉传感器进行校准,并从校准过程中获得内部和外部参数,然后计算转换矩阵,将深度数据投影到绿蓝色图像域。其次,构建了一个三维手部穴位数据集,用于穴位的定位和可视化。此外,从三维视觉传感器获得基于颜色卷积神经网络的数据被转换为点云表示。对点云数据进行压缩,并从输入的整体点云中提取有效点,以去除由于不同传感器限制、对象反射率和不同光强水平而不属于对象表面的异常值。第三,采用基于颜色卷积神经网络和深度卷积神经网络融合的三维穴位定位新方法的融合,实现三维定位。然后,将三维坐标输入机械手,进行人工控制的艾灸治疗。此外,还构建了由红绿蓝色图像域和手部深度图像组成的三维穴位数据集,对网络进行训练、验证和测试。最后,本文还介绍了利用多轴机器人进行温控灸疗的三维CAD设计。基于卷积神经网络的定位被整合到相关计算机中的软件部分中,该计算机与负责系统运行的独立控制面板无线连接。超声波传感器确保治疗期间的温度保持在规定的范围内,非接触式温度传感器控制艾条与人体皮肤之间的最佳距离。该网络能够定位5组穴位,且平均定位误差小于0.09。该实验进一步验证了本文提出方法的有效性,为后续开发自动艾灸机器人奠定了基础。

关键词：穴位定位摄像机标定卷积神经网络特征提取手眼协调

H_∞ Preview Control for Automatic Carrier Landing

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2019年第6期36卷 919-926页

作者： FARHAN masood XUE Yixuan' ZHEN Ziyang YANG Liuqing College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China Jiangsu Key Laboratory of Internet of Things and Control Technologies Nanjing 210016P.R.China

This paper focuses on the application of H_∞preview control in automatic carrier landing system(ACLS)for carrier-based *** to the mutual movement between aircraft and carrier,the landing process becomes considerably more challenging compared to a conventional runway *** systems mitigate this by predicting deck motion and generating ideal glide slope path for ***,this predicted glide slope information is available in advance,conventional control structures are still unable to use this future information.H_∞preview control has the ability to utilize this future information for improving tracking response and disturbance *** process of incorporating preview information into ACLS framework and synthesizing the H_∞preview controller is *** methodology is verified using the example of F/A-18 automatic carrier landing problem and results are presented.

关键词： H∞control preview control carrierbased aircraft automatic carrier landing robust preview control

A comparative analysis of radon (^(222)Rn) concentration in the different water sources of Ganderbal, Jammu and Kashmir

在线全文

学校读者我要写书评

暂无评论

Radiation Detection Technology and Methods 2023年第4期7卷 627-635页

作者： Mehak Mohi u Din Shakeel Simnani Salik Nazir Sajad masood Mohammad Rafiq Chakan Supriya Rani Amit Kumar Singla Shahid Saleem Department of Physics University of KashmirSrinagarJ&K190006India Department of Physics Maharaja Ranjit Singh Punjab Technical UniversityBathindaPunjab151001India Department of Geography and Disaster Management University of KashmirSrinagarJ&K190006India

Introduction Radon,a known carcinogen,is the second largest cause of lung carcinoma as per the World Health *** primary purpose of the present research is to examine and compare the concentrations of radon gas(^(222)Rn)in different sources of water in the Lar and Ganderbal tehsils of the district of Ganderbal,Jammu and *** groundwater ^(222)Rn concentrations indicate higher indoor radon concentrations and long-term radon exposure is extremely harmful to human health as it increases the risk of developing lung *** A scintillation-based radon monitor called the smart RnDuo was used to quantify the amount of radon activity present in water samples collected from different locations of Lar and Ganderbal regions of district *** Average radon(^(222)Rn)concentration of 1.84 BqL^(−1) was found in tap waters,3.73 BqL^(−1) in surface waters,16.56 BqL^(−1) in borewells,and 20.82 BqL^(−1) in *** higher radon concentration in groundwater is because of the direct and prolonged interaction of uranium-rich rocks and soil with the ***,monitoring and regulating radon levels in these water sources is crucial to ensure public health and safety.

关键词： Groundwater quality Ganderbal ^(222)Rn detection Scintilation detector

Assessing impacts of energy storage on resilience of distribution systems against hurricanes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第4期7卷 731-740页

作者： Hieu T.NGUYEN John W.MUHS masood PARVANIA Department of Electrical and Computer Engineering University of UtahSalt Lake CityUT 84112USA

This paper develops a comprehensive framework to analyze the impact of energy storage on improving the resilience of distribution systems against *** paper first develops a spatio-temporal model of progressing hurricane when making landfall that can be used to anticipate outage scenarios caused by the gust-wind *** optimization model is then developed for optimizing the operation of distribution systems during hurricane that captures both pre-outage and post-outage network operation *** simulations are performed on the modified IEEE 33-bus distribution system with real hurricane data in Houston to demonstrate the effectiveness of the proposed model.

关键词： Resilience Hurricane Energy storage Distribution system

Duct-to-mucosa versus invagination pancreaticojejunostomy after pancreaticoduodenectomy： a meta-analysis

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2013年第22期126卷 4340-4347页

作者： BAI Xue-li ZHANG Qi Noman masood Waqas masood GAO Shun-liang ZHANG Yun Shazmeen Shahed LIANG Ting-bo Department of Hepatobiliary and Pancreatic Surgery the Second Affiliated Hospital Zhejiang University School of Medicine. Hangzhou Zhejiang 310009 China Zhejiang University School of Medicine Hangzhou Zhejiang310058 China

Background Postoperative pancreatic fistula remains one of the most common and troublesome complications following pancreaticoduodenectomy. No consensus exists regarding the optimal pancreaticojejunostomy reconstruction technique to reduce this complication. We aimed to perform a systematic review comparing two commonly used techniques of pancreaticojejunostomy reconstruction （duct-to-mucosa versus invagination）, by meta-analysis and assessment of evidence quality. Methods Databases searched including The Cochrane Library, Medline, PubMed, Embase, etc. Randomized controlled trials （RCTs） comparing duct-to-mucosa and invagination pancreaticojejunostomy were included. Outcomes of interest were pancreatic fistula rate, mortality, morbidity, reoperation and hospital stay. Pooled estimates were expressed as risk ratio （RR） or mean difference. Results From 321 identified abstracts, four RCTs （467 patients; duct-to-mucosa： 232; invagination： 235） were included. Pancreatic fistula rate （RR, 0.74; 95% confidence interval （C/）： 0.24-2.28; P=0.60）, mortality （RR, 1.18; 95% CI： 0.39- 3.54; P=0.77）, morbidity （RR, 0.91; 95% CI： 0.69-1.21; P=0.53）, reoperation （RR, 1.09; 95% CI： 0.54-2.22; P=-0.81） and hospital stay （mean difference, -1.78; 95% CI： -4.60-1.04; P=0.22） were similar between techniques. Conclusions Duct-to-mucosa and invagination pancreaticojejunostomy are comparable with regards to assessed parameters. High-quality, large-volume, multi-center RCTs with standard outcome definitions are required.

关键词： duct-to-mucosa invagination pancreaticojejunostomy, pancreaticoduodenectomy meta-analysis