T=题名(书名、题名),A=作者(责任者),K=主题词,P=出版物名称,PU=出版社名称,O=机构(作者单位、学位授予单位、专利申请人),L=中图分类号,C=学科分类号,U=全部字段,Y=年(出版发行年、学位年度、标准发布年)
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摘要:The problem of designing passive fault-tolerant flight controller is addressed when the normal and faulty cases are prescribed. First of all, the considered fault and fault-free cases are formed by polytopes. As considering that the safety of a post-fault system is directly related to the maximum values of physical variables in the system, peak-to-peak gain is selected to represent the relationships among the amplitudes of actuator outputs, system outputs, and reference commands. Based on the parameter dependent Lyapunov and slack methods, the passive fault-tolerant flight controllers in the absence/presence of system uncertainty for actuator failure cases are designed, respectively. Case studies of an airplane under actuator failures are carried out to validate the effectiveness of the proposed approach
摘要:Since digital circuits have been widely and thoroughly applied in various fields, electronic systems are increasingly more complicated and require greater reliability. Faults may occur in electronic systems in complicated environments. If immediate field repairs are not made on the faults, electronic systems will not run normally, and this will lead to serious losses. The traditional method for improving system reliability based on redundant fault-tolerant technique has been unable to meet the requirements. Therefore, on the basis of(evolvable hardware)-based and(reparation balance technology)-based electronic circuit fault self-repair strategy proposed in our preliminary work, the optimal design of rectification circuits(RTCs) in electronic circuit fault self-repair based on global signal optimization is deeply researched in this paper. First of all, the basic theory of RTC optimal design based on global signal optimization is proposed. Secondly, relevant considerations and suitable ranges are analyzed. Then, the basic flow of RTC optimal design is researched. Eventually, a typical circuit is selected for simulation verification, and detailed simulated analysis is made on five circumstances that occur during RTC evolution. The simulation results prove that compared with the conventional design method based RTC, the global signal optimization design method based RTC is lower in hardware cost, faster in circuit evolution, higher in convergent precision, and higher in circuit evolution success rate. Therefore, the global signal optimization based RTC optimal design method applied in the electronic circuit fault self-repair technology is proven to be feasible, effective, and advantageous.
摘要:This paper analyzes the effects of nanoporous surface on heat transfer temperaments of assorted thermal conductingmaterials. A phenomenal proposal of wielding the surface roughness to ameliorate the heat transfer ratehas been discovered. The maximum increase of heat transfer rate procured by nanoporous layers is 133.3% higherthan the polished bare metals of surface roughness 0.2μm. This plays an imperative role in designing compact refrigerationsystems, chemical and thermal power plants. Experimental results picture a formidable upswing of58.3% heat transfer in chemically etched metals of surface roughness 3 μm, 133.3% in nanoporous surface of porosity75-95 nm formed by electrochemical anodization, and porosity of 40-50 nm formed by spray pyrolysis increasesthe heat transfer by 130%. Effects of porosity, flow velocity and scaling on the energy transfer are alsoscrutinized. This paper also analyzes the multifarious modes of nanoporous fabrication, to contrive both prodigiousand provident system.
摘要:This paper presents the development of a coarse-fine dual precision positioning stage to achieve long travel range and high *** fine stage is arranged in series with a coarse *** key in the fine stage design is the choice of a toggle mechanism for a tight mechanical loop with high stiffness and *** designed the toggle mechanism for reduction of the displacement to suppress signal *** performance of the coarse and fine stages was verified with an optical encoder and capacitive sensor,*** measurement results show that the dual mechanism has a travel range of 1 mm and resolution of 30 nm.
摘要:Small propeller-type wind turbines have a low Reynolds number,limiting the number of usable airfoil ***,their design method is not sufBciently established,and their performance is often *** ultimate goal of this research is to establish high-performance design guidelines and design methods for small propeller-type wind *** that end,we designed two rotors:Rotor A,based on the rotor optimum design method from the blade element momentum theory,and Rotor B,in which the chord length of the tip is extended and the chord length distribution is *** examined performance characteristics and flow fields of the two rotors through wind tunnel experiments and numerical *** results revealed that the maximum output tip speed ratio of Rotor B shifted lower than that of Rotor A,but the maximum output coefficient increased by approximately 38.7%.Rotors A and B experienced a large-scale separation on the hub side,which extended to the mean in Rotor *** difference in separation had an impact on the significant decrease in Rotor A's output compared to the design value and the increase in Rotor B's output compared to Rotor A.
摘要:With the continuous increase of social and economic competitiveness, the position of advertising becomes more and more important. For attracting people's attention to the advertising, merchants should not only rely on novel advertising creativity and also add some sentiment elements in advertising design under the background of today's advertising all over the world. Sentiments are the most capable of touching human nerves so as to leave a deep impression in the minds of people, so the quality of advertising can be well improved if appropriate sentiment elements are added in advertising design. In this paper, the application of emotional elements to advertising design is specifically discussed from emotional elements classification, main application methods, and matters needing attention.
摘要:The wear rate between the rotors of a hypotrochoidal gear pump is *** the knowledge of shape design on the rotors,the contact stresses without hydrodynamic effect between the rotor teeth were evaluated through the calculation of the Hertzian contact *** on the above results and the sliding velocity between the rotors,a genetic algorithm (GA) was used as an optimization technique forminimizing the wear rate proportional factor (WRPF).The result shows that the wear rate or the WRPF can be reduced considerably,*** 12.8%,throughout the optimization using GA.
摘要:The conceptual design and optimization of a tilt-rotor Micro Air Vehicle(MAV) for a well-defined mission are performed. The objective of this design cycle is to decrease the design time in order to efficiently create a functional tilt-rotor drone. A flight mission is firstly defined for a tiltrotor MAV performing hovering and cruise flight scenarios. Secondly, a complex wing shape is chosen and modeled in order to determine the final shape. The initial shape is scaled in order to acquire an arbitrary wingspan of one meter. For the specific area and wingspan, the aspect ratio of the designed wing shape is found to be equal to 2.32. Thirdly, a constraint analysis of the MAV is performed by using an energy balance analysis for six different flight scenarios. This analysis yields the required power loading and wing loading. Fourthly, the weight of the vehicle is estimated using both statistical and computational methods. After estimating the total weight and the wing loading of the MAV, the surface of the wing is determined, yielding a final wingspan of 0.76 m. Subsequently, considering the total weight of the designed MAV, the needed lift coefficient is ***, using the lift coefficient in conjunction with XLFR5, a batch of airfoils is selected and analyzed to evaluate the aerodynamic coefficients of the wing with each airfoil. This analysis ultimately leads to the optimum airfoil being selected. Finally, design of the fuselage and tail, internal components selection, and servo-mechanisms design are carried out prior to a stability analysis. All these proposed steps are needed to design efficient and functional tilt-rotor MAVs.
摘要:This paper presents the fundamentals of a continuous adjoint method and the applications of this method to the aerodynamic design optimization of both external and internal *** formulation of the continuous adjoint equations and the corresponding boundary conditions are *** the adjoint method,the complete gradient information needed in the design optimization can be obtained by solving the governing flow equations and the corresponding adjoint equations only once for each cost function,regardless of the number of design *** inverse design of airfoil is firstly performed to study the accuracy of the adjoint gradient and the effectiveness of the adjoint method as an inverse design *** the method is used to perform a series of single and multiple point design optimization problems involving the drag reduction of airfoil,wing,and wing-body configuration,and the aerodynamic performance improvement of turbine and compressor blade *** results demonstrate that the continuous adjoint method can efficiently and significantly improve the aerodynamic performance of the design in a shape optimization problem.
摘要:Monodisperse aerosols are essential in many applications, such as filter testing, aerosol instrument calibration, and experiments for validating models. This paper describes the design principle, construction, and performance of a monodisperse-aerosol generation system that comprises an atomizer, virtual impactor, microcontroller-based isokinetic probe, wind tunnel, and velocity measurement device. The size distribution of the produced monodisperse aerosols was determined by an optical particle counter. The effects of atomizer characteristics, the rates of minor and major flow, and solution criteria were investigated. It was found that all these parameters affect the generation of monodisperse aerosol. Finally, the expected geometric standard deviation (〈1.25) of monodisperse aerosol particles was obtained with the most suitable atomizer for 10% oleic acid in ethyl alcohol solution with 5%-15% minor flow, where the ratio between the nozzle-to-probe distance and acceleration-nozzle-exit diameter was 0.66. The con- structed monodisperse-aerosol-generation system can be used for instrumental calibration and aerosol research.
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