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Whittle’s Index Based Sensor Scheduling for Multiprocess Systems Under DoS Attacks

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Journal of Systems Science & Complexity 2024年第1期37卷 329-350页

作者： cai Zai DING Kemi Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and TechnologyShenzhen 518055China.

In this paper,the authors consider how to design defensive countermeasures against DoS attacks for remote state estimation of multiprocess *** each system,a sensor will measure its state and transmits the data packets through an unreliable channel which is vulnerable to be jammed by an *** limited communication bandwidth,only a subset of sensors are allowed for data transmission,and how to select the optimal one to maximize the accuracy of remote state estimation is the focus of the proposed *** authors first formulate this problem as a Markov decision process and investigate the existence of optimal ***,the authors demonstrate the piecewise monotonicity structure of optimal *** the difficulty of obtaining an optimal policy of large-scale problems,the authors develop a suboptimal heuristic policy based on the aforementioned policy structure and Whittle’s ***,a closed form of the indices is derived in order to reduce implementation complexity of proposed scheduling policy and numerical examples are provided to illustrate the proposed developed results.

关键词： DoS attacks Kalman filter remote state estimation Whittle’s index.

Inspection interval optimization for aircraft composite structures with dent and delamination damage

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Journal of Systems Engineering and Electronics 2021年第1期32卷 252-260页

作者： cai Jing DAI Dingqiang College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China

The optimization of inspection intervals for composite structures has been proposed,but only one damage type,dent damage,has been addressed so *** present study focuses on the two main damage types of dent and delamination,and a model for optimizing the inspection interval of composite structures is proposed to minimize the total maintenance cost on the premise that the probability of structure failure will not exceed the acceptable *** order to analyze the damage characteristics and the residual strength of the composite structure,the frequency,energy,size,and depth of the damage are studied,and the situation of missing detection during the inspection is *** structural residual strength and total maintenance cost are quantified corresponding to different inspection *** proposed optimization method relieves the constraints in previous simulation methods,and is more consistent with the actual ***,the outer wing of aircraft is taken as an example,and with the historical cases and experimental data,the optimization method is *** optimal inspection interval is shorter than the actually implemented inspection interval,and the corresponding maintenance cost is reduced by 23.3%.The result shows the feasibility and effectiveness of the proposed optimization method.

关键词： civil aircraft composite structure accidental impact damage failure probability inspection interval

Experimental and numerical investigations of the mechanical behavior of half sandwich laminate in the context of blanking

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Advances in Manufacturing 2020年第2期8卷 177-188页

作者： Sheng cai Lin Chen Department of V ehicle Engineering College of EngineeringChina Agricultural UniversityBeijing 100083People's Republic of China CW Bearing GmbH Hamburg 22113Germany

In this study,the complex mechanical behavior of an aluminum/low-density polyethylene(LDPE)half sandwich structure was investigated during the blanking *** tests were conducted for the polymer and metal layer and the delamination behavior of the adhesive between the two layers.A new testing device was designed for detecting the delamination under tensile *** finite element models were established for the mechanical tests of the metal layer and the delamination of both layers for inverse parameter *** parameters for Lemaitre-type damage,Drucker-Prager,and cohesive zone modeIs were identified for the metal,polymer,and adhesive,respectively.A finiteelement(FE)model was established for the blanking process of the sandwich *** experimental forcedisplacement curves,obtained in the blanking process of the half sandwich sheet,were compared with the predicted results of the FE *** results showed that the predicted force-displacement curves and the experimental results were in good ***,the correlation between cutting clearance and changes in the forcedisplacement curves was *** feature values quantitatively described the imperfection of the experimental cutting *** effect of punch clearance on these values was studied numerically and *** results indicated that a smaller clearance generated a better cutting-edge *** stress state of the half sandwich structure during blanking was analyzed using the established FE model.

关键词： Sandwich plates Blanking Continuum damage mechanics(CDM) Drucker-Prager model Cohesive zone model

Pre-inflation and trans-Planckian censorship

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Science China(Physics,Mechanics & Astronomy) 2020年第11期63卷 27-35页

作者： Yong cai YunSong Piao School of Physics University of Chinese Academy of SciencesBeijing 100049China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China

We investigate the implication of trans-Planckian censorship conjecture(TCC)for the initial state of primordial *** is possible to set the state of perturbation modes in the infinite past as the Minkowski vacuum,only if the pre-inflationary era is *** calculate the evolution of the perturbation modes in such a pre-inflationary era and show that at the beginning of inflation the perturbation modes with wavelengths much shorter than the Hubble scale(but still larger than the Planck length scale)will behave as they are in the Bunch-Davis ***,a past-complete pre-inflationary evolution may automatically prepare the initial state required for the inflationary perturbations at the CMB window while obeying the TCC.

关键词： inflation primordial perturbation trans-Planckian censorship conjecture

Mathematical framework of nonlinear elastic waves propagating in pre-stressed media

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1705-1716页

作者： Jiangcheng cai Mingxi DENG College of Aerospace Engineering Chongqing UniversityChongqing 400044China

Acoustic nonlinearity holds potential as a method for assessing material *** to the acoustoelastic effect,where the velocity of elastic waves is influenced by third-order elastic constants,the propagation of nonlinear acoustic waves in pre-stressed materials would be influenced by higher-order elastic *** this,there has been a notable absence of research exploring this ***,this paper aims to establish a theoretical framework for governing the propagation of nonlinear acoustic waves in pre-stressed *** delves into the impact of pre-stress on higher-order material parameters,and specifically examines the propagation of one-dimensional acoustic waves within the contexts of the uniaxial stress and the biaxial *** paper establishes a theoretical foundation for exploring the application of nonlinear ultrasonic techniques to measure pre-stress in materials.

关键词： acoustoelastic effect nonlinear elastic wave pre-stress medium higher-order elastic constant

Heat transfer analysis of feedthrough flange under high alternating current condition

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Science China(Technological Sciences) 2020年第4期63卷 686-692页

作者： cai Xiao WANG HaiPeng School of Physical Science and Technology Northwestern Poly technical UniversityXi'an 710072China

The heat transfer characteristics of feedthrough flange under high alternating current excitation were investigated by threedimensional finite element *** correlations between the heat transfer behaviors and system parameters including applied current,ceramic thickness and working time were discussed comprehensively.A remarkable absorbed power beyond 100 W in flange would be produced by the electromagnetic field from *** natural cooling condition,there is an obvious temperature rise about 40℃in the flange center after 10 min of current *** types of water cooling solutions acting on flange surface,*** type,circle type and S type solutions,were proposed to reduce the flange temperature under high alternating current and long working time *** the S type water cooling mode,the best cooling effect can be achieved that the maximum temperature rise is about 20℃and the average temperature rise is less than 5℃.

关键词： heat transfer cooling solution feedthrough flange induction heating

Temperature Dependence of Laminar Burning Velocity in Ammonia/Dimethyl Ether-air Premixed Flames

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Journal of Thermal Science 2022年第1期31卷 189-197页

作者： cai Tao ZHAO Dan Department of Mechanical Engineering College of EngineeringUniversity of CanterburyChristchurch 8041New Zealand

The combustion of ammonia(NH3)has attracted wide interest in fuel vehicle engines,marine engines,and power generators to mitigate carbon dioxide ***,the relatively low laminar flame speed presents a technical barrier for this renewable fuel to be used in *** work is concerned with numerical examining the effects of elevating inlet temperature on the laminar burning velocity of NH3/air flames with various contents of dimethyl ether(DME)using ID freely propagating flame calculations,and to shed light on the flame enhancement *** this,the mechanism is first validated by comparing the numerical predictions with experimental *** show that increasing the inlet temperature has a positive effect on the laminar burning velocity of pure NH3/DME/air *** is revealed that elevating inlet temperature contributes to a higher adiabatic flame temperature,which is beneficial to the overall chemical reaction ***,the thermal diffusivity of the binary mixture is observed to increase substantially as *** kinetic and sensitivities analyses reveal that the inlet temperature has a minimal effect on the reaction pathway,leading to the relative importance of the dominant chain branching over terminating reaction steps to be varied *** present work confirms that the flame speed enhancement with increasing inlet temperature is primarily the synergetic result of the thermal and diffusion effects,rather than the chemical effect.

关键词： ammonia dimethyl ether laminar burning velocity temperature dependence kinetic analyses

A LINE SEARCH FILTER INEXACT SQP METHOD FOR NONLINEAR EQUALITY CONSTRAINED OPTIMIZATION

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Journal of Systems Science & Complexity 2012年第5期25卷 950-963页

作者： Li cai Detong ZHU Department of Mathematics Shanghai Normal University College of Business Shanghai Normal University

This paper proposes an inexact SQP method in association with line search filter technique for solving nonlinear equality constrained optimization. For large-scale applications, it is expensive to get an exact search direction, and hence the authors use an inexact method that finds an approximate solution satisfying some appropriate conditions. The global convergence of the proposed algorithm is established by using line search filter technique. The second-order correction step is used to overcome the Maratos effect, while the line search filter inexact SQP method has q-superlinear local convergence rate. Finally, the results of numerical experiments indicate that the proposed method is efficient for the given test problems.

关键词： Constrained optimization convergence filter method inexact method maratos effect.

Human Following for Outdoor Mobile Robots Based on Point-Cloud's Appearance Model

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Chinese Journal of Electronics 2021年第6期30卷 1087-1095页

作者： GONG Linxi cai Yunfei School of Computer Science and Engineering Nanjing University of Science and Technology

In this paper, we propose a point-cloudbased algorithm for human-following robots to detect and follow the target person in a complex outdoor environment. Specifically, we exploit Ada Boost to train a binary classifier in a designed feature space based on sparse point-cloud to distinguish the target person from other objects. Then a particle filter is applied to continuously track the target’s position. Motivated by the interference of obstacles in long-distance human-following scenarios, a motion plan algorithm based on vector field histogram is adopted. Experiments are carried out both on the dataset we collected and in real application scenarios. The results show that our algorithm has the ability of real-time target detection and tracking, and is robust to deal with complex situations in outdoor environments.

关键词： outdoor environments outdoor mobile robots particle filter target person point-cloud-based algorithm path planning collision avoidance designed feature space binary classifier mobile robots tracking real-time target detection particle filtering (numerical methods) sparse point-cloud learning (artificial intelligence) complex outdoor environment motion plan algorithm vector field histogram object detection