检索结果-南通市图书馆

Journal of Hydrodynamics 2014年第2期26卷 326-338页

作者： meziani bachir OURRAD Ouerdia Laboratoire de Physique Théorique Université A. Mira de Bejaia Campus de targua Ouzemour

Surface tension effects on fluid sloshing in a tank subjected to external excitation has been less studied. This work aims at understanding this phenomenon in order to derive practical solutions to problems faced in several engineering. A tank containing a fluid with a free surface is submitted to gravity and capillary forces and subject to external dynamic excitation. Introduction of vertical sinusoidal dynamical excitation leads to a problem of paramtric oscillations governed by the Mathieu equation. Analysis of the Mathieu equation shows the existence of stable and unstable regions in the stability diagram. Some results induced by harmonic excitations on the fluid sloshing are presented. When the external dynamical excitation amplitude ~ is small, periodic solutions appear in stable regions and when e increases, the fluid behavior is not perfectly periodic and the amplitudes are not regular. Nonlinear effects make the behavior of the fluid complicated and render it almost unpredictable. In stable regions, the solution remains bounded at any time. When changing the perturbation parameter 6, the phase difference increases and also with the increase of the surface tension.

关键词： parametric sloshing capillary effects stability

Socioeconomic impact of urban redevelopment in inner city of Ningbo

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第8期7卷 1386-1395页

作者： BACHOUR bachir Department of Architecture Southeast University Nanjing 210096 China

Since market-oriented economy reform, China has experienced significant changes in urban landscapes and the internal structure of cities. Housing marketization provides an opportunity for households to choose their residences. However, not all households benefit equally from residential relocation. Residential relocation in urban China has relatively strong association with the household’s position within the spectrum from state redistribution to market reward than with life cycles and consequent adjustment of housing demand, which are the primary reasons for residential mobility in a mature market. In this research we focused on social aspects, mainly relating to the impact of urban redevelopment in inner city of Ningbo and the resultant potential housing problem. This research is based on a questionnaire survey that was conducted in three neighborhoods redeveloped at different time periods in the past fifteen years. The findings suggest that new strategy of redevelopment of the integrated envi-ronment of the old city while still improving the living condition for its residents can be heard due to the efforts of many people at various positions. Yet, many things need to be done to change people’s ideas: information and education through newspapers, academic discussions through academic journals, conferences, and reports to decision makers.

关键词： Urban redevelopment Housing reform Neighborhood Urban structure Socioeconomic Social interaction

Nano-confinement of biomolecules： Hydrophilic confinement promotes structural order and enhances mobility of water molecules

在线全文

学校读者我要写书评

暂无评论

Nano Research 2016年第2期9卷 273-281页

作者： bachir Aoun Daniela Russo Argonne National Laboratory Chicago IL 60439 USA CNR-IOM c/o Institut Laue-Langevin 38400 Grenoble France Institut Lumiere Matiere Universite de Lyon 69622 Lyon France

Molecular dynamics simulations have been used to investigate the confinement packing characteristics of small hydrophilic （N-acetyl-glycine-methylamide, Nagma） and hydrophobic （N-acetyl-leucine-methylamide, Nalma） biomolecules in large diameter single-wall carbon nanotubes （SWCNTs）. We find that hydrophilic biomolecules easily fill the nanotube and self organize into a geometrical configuration which reminds the water structural organization under SWCNT confinement. The packing of hydrophilic biomolecules inside the cylinder confines all water molecules in its core, which enhances their mobility. Conversely, hydrophobic biomolecules accommodate into the nanotubes with a trend for homogeneous filling, which generate unstable small pockets of water and drive toward a state of dehydration. These results shed light on key parameters important for the encapsulation of biomolecules with direct relevance for long-term storage and prevention of degradation.

关键词： nano-confinement protein folding hydration water carbon nanotube drug delivery

Impact of preprocessing on medical data classification

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2016年第6期10卷 1082-1102页

作者： Sarab ALMUHAIDEB Mohamed El bachir MENAI Computer Science Department College of Computer and Information Sciences Prince Sultan University Riyadh 11586 Saudi Arabia

The significance of the preprocessing stage in any data mining task is well known. Before attempting medical data classification, characteristics of medical datasets, including noise, incompleteness, and the existence of multiple and possibly irrelevant features, need to be addressed. In this paper, we show that selecting the right combination of prepro- cessing methods has a considerable impact on the classification potential of a dataset. The preprocessing operations con- sidered include the discretization of numeric attributes, the selection of attribute subset（s）, and the handling of missing values. The classification is performed by an ant colony optimization algorithm as a case study. Experimental results on 25 real-world medical datasets show that a significant relative improvement in predictive accuracy, exceeding 60% in some cases, is obtained.

关键词： classification ant colony optimization medical data classification preprocessing feature subset selection,discretization

Benchmarking YOLOv5 models for improved human detection in search and rescue missions

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2024年第1期22卷 70-80页

作者： Namat bachir Qurban Ali Memon Electrical Engineering Department College of EngineeringUnited Arab Emirates UniversityAl Ain15551United Arab Emirates

Drone or unmanned aerial vehicle(UAV)technology has undergone significant *** technology allows UAV to carry out a wide range of tasks with an increasing level of sophistication,since drones can cover a large area with ***,the increasing number of computer vision applications utilizing deep learning provides a unique insight into such *** primary target in UAV-based detection applications is humans,yet aerial recordings are not included in the massive datasets used to train object detectors,which makes it necessary to gather the model data from such *** only look once(YOLO)version 4,RetinaNet,faster region-based convolutional neural network(R-CNN),and cascade R-CNN are several well-known detectors that have been studied in the past using a variety of datasets to replicate rescue ***,we used the search and rescue(SAR)dataset to train the you only look once version 5(YOLOv5)algorithm to validate its speed,accuracy,and low false detection *** comparison to YOLOv4 and R-CNN,the highest mean average accuracy of 96.9%is obtained by *** comparison,experimental findings utilizing the SAR and the human rescue imaging database on land(HERIDAL)datasets are *** results show that the YOLOv5-based approach is the most successful human detection model for SAR missions.

关键词： Unmanned aerial vehicle(UAV) Search and rescue(SAR) You look only once(YOLO)model You only look once version 5 (YOLOv5)

A Simplified Numerical Study of the Kr/Cl_2 Plasma Chemistry in Dielectric Barrier Discharge

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2013年第4期15卷 343-349页

作者： N.LARBI DAHO bachir A.BELASRI Laboratoire de physique des plasmas mat'eriaux conducteurs et leurs applications LPPMCA Universit'e USTO'MBOran Algeria

In this paper, the generation of excimers and exciplexe radiation in mixtures of rare gas with halogen by homogeneous dielectric barrier discharge （DBD） is investigated. The typical characteristics of an excilamp based on KrCI＊ exciplexe molecules and the kinetic processes for the formation and the decay of this molecules in the Kr/Cl2 mixture are studied. The computer model developed is based on the Kr/Cl2 mixture chemistry, the equivalent electric circuit and the Boltzmann equations. The importance in the kinetic processes of some species such as the metastable state of Krypton （Kr＊（3P0,2）） and the negative ion of chloride （C1-） is considered. The results illustrate the time variations of charged species （ne, Kr＋, CI-, Cl＋, Cl＋, Kr＋）, excited atoms and molecules （Kr＊（3p0,2）, Kr＊（3P1）, Cl＊, Cl2）, the excimers （Kr, KrCl＊（B）, KrCI＊（C）, Kr2Cl＊） and the UV photon concentrations （in 222 nm, 235 nm, 258 nm and 325 nm range）. The effects of chlorine concentration and the total gas pressure in the Kr-Cl2 discharge on the electric parameters and radiation emissions are investigated.

关键词： rare gas kinetic homogenous discharge dielectric barrier discharge KrCl*excilamp

Circle-criterion Based Nonlinear Observer Design for Sensorless Induction Motor Control

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2014年第6期11卷 598-604页

作者： Wafa Bourbia Farid Berrezzek bachir Bensaker University Badji Mokhtar Department of Electrotechnic BP.12 Annaba 23000 Algeria University Med Cherif Messadia Souk Ahras 41000 Algeria Laboratory of Electromechanical Systems University Badji Mokhtar BP.12 Annaba 23000 Algeria

This paper deals with the design of a nonlinear observer for sensorless induction motor control. Based upon the circle criterion approach, a nonlinear observer is designed to estimate pertinent but unmeasurable state variables of the considered induction machine for sensorless control purpose. The observer gain matrices are computed as a solution of linear matrix inequalities(LMI) that ensure the stability conditions of the state observer error dynamics in the sense of Lyapunov concepts. Measured and estimated state variables can be exploited to perform a state feedback control of the machine system. The simulation results are presented to illustrate the effectiveness of the proposed approach for nonlinear observer design.

关键词： Nonlinear observer circle-criterion Lyapunov stability linear matrix inequalties (LMI) induction motor

A Taxonomy of Exact Methods for Partial Max-SAT

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2013年第2期28卷 232-246页

作者： Mohamed El bachir Menai Tasniem Nasser Al-Yahya Department of Computer Science College of Computer and Information Sciences King Saud University

Partial Maximum Boolean Satisfiability （Partial Max-SAT or PMSAT） is an optimization variant of Boolean satisfiability （SAT） problem, in which a variable assignment is required to satisfy all hard clauses and a maximum number of soft clauses in a Boolean formula. PMSAT is considered as an interesting encoding domain to many reaHife problems for which a solution is acceptable even if some constraints are violated. Amongst the problems that can be formulated as such are planning and scheduling. New insights into the study of PMSAT problem have been gained since the introduction of the Max-SAT evaluations in 2006. Indeed, several PMSAT exact solvers have been developed based mainly on the Davis- Putnam-Logemann-Loveland （DPLL） procedure and Branch and Bound （B^B） algorithms. In this paper, we investigate and analyze a number of exact methods for PMSAT. We propose a taxonomy of the main exact methods within a general framework that integrates their various techniques into a unified perspective. We show its effectiveness by using it to classify PMSAT exact solvers which participated in the 2007~2011 Max-SAT evaluations, emphasizing on the most promising research directions.

关键词： Partial Max-SAT Davis-Putnam-Logenmann-Loveland branch and bound unsatisfiability pseudo-Boolean optimization

A Variable Stiffness Soft Gripper Using Granular Jamming and Biologically Inspired Pneumatic Muscles

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2018年第2期15卷 236-246页

作者： Loai AI Abeach Samia Nefti-meziani Theo Theodoridis Steve Davis Autonomous Systems and Robotics Research Centre University of Salford Salford M5 4WT UK Computer Engineering Department College of Engineering Basra University Basra 61004 Iraq

As the domains, in which robots operate change the objects a robot may be required to grasp and manipulate, are likely to vary sig- nificantly and often. Furthermore there is increasing likelihood that in the future robots will work collaboratively alongside people. There has therefore been interest in the development of biologically inspired robot designs which take inspiration from nature. This paper pre- sents the design and testing of a variable stiffness, three fingered soft gripper, which uses pneumatic muscles to actuate the fingers and granular jamming to vary their stiffness. This gripper is able to adjust its stiffness depending upon how fragile/deformable the object being grasped is. It is also lightweight and low inertia, making it better suited to operation near people. Each finger is formed from a cylindrical rubber bladder filled with a granular material. It is shown how decreasing the pressure inside the finger increases the jamming effect and raises finger stiffness. The paper shows experimentally how the finger stiffness can be increased from 21 N·m^-1 to 71 N·m^-1. The paper also describes the kinematics of the fingers and demonstrates how they can be position-controlled at a range of different stiffness values.

关键词： biologically inspired robots variable stiffness actuation soft robotics soft grippers pneumatic muscles

Two Bioinspired Mobile Manipulators with Rolling Locomotion

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 Bionic Engineering 2016年第1期13卷 48-58页

作者： Saber Mahboubi Heydarabad Mir Masoud Seyyed Fakhrabadi Steve Davis Samia Nefti-meziani School of Computing Science & Engineering University of Salford Manchester The Crescent M5 4WT UK School of Mechanical Engineering College of Engineering University of Tehran Tehran Iran

This paper deals with two novel structures for mobile robots. The original inspiration of the robots comes from a sala- mander and a specific kind of spiders. Our robots have some especial moving capabilities causing to increase the robot ma- neuverability. Indeed, the capability of rolling motion is added to ordinary quadruped robots. This capability causes increment in maneuvering of the robots. Manipulators can be embedded into the robots to add the ability of transferring materials into the shell and conducting some tasks such as repairing. In this paper, after analysis of motion principles of the rolling robots, their dynanlic equations are derived. Different simulations of two bioinspired mobile robots are presented in order to scrutinize various capabilities of the proposed designs. Walking capabilities of the robots and their advantages are discussed in detail. The comprehensive simulation results of the robots in various motion modes are presented. Finally the first prototype is introduced to verify the motion mechanisms.

关键词： bionics rolling robot quadruped robot Lagrange equations