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1.
A weighted Hpω(G) multiplier theorem on the multiplier operator T associated with a function m∈ L∞ (Γ) is shown and the atomic decomposition of functions fin Hp*(G) is obtained, where G is a Vilenkin group, r its dual, 0 < p≤1 and ω is a weight on G which is more general than that proposed by C. W. Onneweer et al.  相似文献   

2.
For desirable quality of service, content providers aim at covering content requests by large network caches. Content caching has been considered as a fundamental module in network architecture. There exist few studies on the optimization of content caching. Most existing works focus on the design of content measurement,and the cached content is replaced by a new one based on the given metric. Therefore, the performance for service provision with multiple levels is decreased. This paper investigates the problem of finding optimal timer for each content. According to the given timer, the caching policies determine whether to cache a content and which existing content should be replaced, when a content miss occurs. Aiming to maximize the aggregate utility with capacity constraint, this problem is formalized as an integer optimization problem. A linear programming based approximation algorithm is proposed, and the approximation ratio is proved. Furthermore, the problem of content caching with relaxed constraints is given. A Lagrange multiplier based approximation algorithm with polynomial time complexity is proposed. Experimental results show that the proposed algorithms have better performance.  相似文献   

3.
An efficient way to improve the efficiency of the applications based on formal concept analysis (FCA) is to construct the needed part of concept lattice used by applications. Inspired by this idea, an approach that constructs lower concept semi-lattice called non-frequent concept semi-lattice in this paper is introduced, and the method is based on subposition assembly. Primarily, we illustrate the theoretical framework of subposition assembly for non-frequent concept semi-lattice. Second, an algorithm called Nocose based on this framework is proposed. Experiments show both theoretical correctness and practicability of the algorithm Nocose.  相似文献   

4.
In order to optimize the sizing and topology of discrete structures together and resist the combinatorial explosion of the solution space,a co-evolutionary design(CED)method based on ant colony optimization(ACO)for discrete structures is proposed.The tailored ant colony optimization for the sizing of structures(TACO-SS)and the tailored ant colony optimization for the topology of structures(TACO-TS)are implemented respectively.Theoretical analysis shows that the computation complexity of each sub-process in CED based on ACO above is polynomial and it guarantees the efficiency of this method.After the parameter settings in TACO-SS and TACO-TS are discussed,the convergence history of a sub-process is studied through an instance in detail.Finally,according to the design examples of the 10-bar and 15-bar trusses under different cases,the effectiveness of the CED based on ACO is validated and the effects of the loads and the deflection constraints on the co-evolutionary design are discussed.  相似文献   

5.
A new structure of ESKD (expert system based on knowledge discovery system KD (D&K)) is first presented on the basis of KD (D&K)-a synthesized knowledge discovery system based on double-base (database and knowledge base) cooperating mechanism. With all new features, ESKD may form a new research direction and provide a great probability for solving the wealth of knowledge in the knowledge base. The general structural frame of ESKD and some sub-systems among ESKD have been described, and the dynamic knowledge base based on double-base cooperating mechanism has been emphased on. According to the result of demonstrative experiment, the structure of ESKD is effective and feasible.  相似文献   

6.
Starting from Maxwell's equations for inhomogeneous media, nonlinear integral equations of the inverse problem of the electromagnetic tomography (EMT) are derived, whose kernel is the dyadic Green's function for the EMT sensor with a homogeneous medium in the object space. Then in terms of ill-posedness of the inverse problem, a Tikhonov-type regularization model is established based on a linearization-approximation of the nonlinear inverse problem. Finally, an iterative algorithm of image reconstruction based on the inverse problem and reconstruction images of some object flows for simplified sensor are given. Initial results of the image reconstruction show that the algorithm based on the inverse problem is superior to those based on the linear back-projection in the quality of image reconstruction.  相似文献   

7.
In this paper, we first present a statistics analysis of the picture distortion caused by quantization, channel errors and subsequent error propagation, and propose rate-distortion (R-D) estimation models which are functions of two parameters, i.e. quantization step and intra refreshing ratio. Second, based on our proposed R-D models, a joint optimal quantization step and intra refreshing ratio selection algorithm is developed by using Lagrange multiplier theory. Next, a novel rate control algorithm, combined with macroblock (MB) coding mode selection, is proposed. The algorithm focuses on bit allocation at group of pictures (GOP) level and picture level to improve the encoding quality, and the MB mode selection addresses improving the local subjective quality within a picture. Finally, extensive simulation resultsshow that our algorithm can make the encoder adapting itself in time to the variation of the channel band-width and significantly improve the end-to-end video quality over packet loss network.  相似文献   

8.
Virtual manufacturing (VM) is an integrated synthetic manufacturing environment exercised to enhance all levels of decision and control in a manufacturing networked enterprise. Autonomous manufacturing island (AMI) is an active, dynamic and flexible production cell in the domain of technology, organization and management. This paper explains the concept of VM, proposes the architecture of VM based on AMI and discusses its characteristics. Lastly, a pilot system of virtual manufacturing based on AMI is introduced.  相似文献   

9.
An estimate of a generalization error bound of the improved support vector regression(SVR)is provided based on our previous work.The boundedness of the error of the improved SVR is proved when the algorithm is applied to the function approximation.  相似文献   

10.
The soft-sensor modeling for fermentation process based on standard support vector regression(SVR) needs to solve the quadratic programming problem(QPP) which will often lead to large computational burdens, slow convergence rate, low solving efficiency, and etc. In order to overcome these problems, a method of soft-sensor modeling for fermentation process based on geometric SVR is presented. In the method, the problem of solving the SVR soft-sensor model is converted into the problem of finding the nearest points between two convex hulls (CHs) or reduced convex hulls (RCHs) in geometry. Then a geometric algorithm is adopted to generate soft-sensor models of fermentation process efficiently. Furthermore, a swarm energy conservation particle swarm optimization (SEC-PSO) algorithm is proposed to seek the optimal parameters of the augmented training sample sets, the RCH size, and the kernel function which are involved in geometric SVR modeling. The method is applied to the soft-sensor modeling for a penicillin fermentation process. The experimental results show that, compared with the method based on the standard SVR, the proposed method of soft-sensor modeling based on geometric SVR for fermentation process can generate accurate soft-sensor models and has much less amount of computation, faster convergence rate, and higher efficiency.  相似文献   

11.
The experimental optimization of a 10 GHz optoelectronic oscillator (OEO) based on a 1.55 μm directly modulated distributed feedback (DFB) laser is demonstrated in this paper. The phase noise of the directly modulated laser (DML) based OEO is significantly reduced by proper selection of the laser’s bias current and by using a dispersion shifted fiber as a delay line. The phase noise performance of the DML OEO achieved after optimization is close to that of a conventional OEO constructed using a commercial DFB laser and a LiNbO 3 Mach-Zehnder modulator. The DML based OEO is most promising for future realization of a miniature OEO architecture with the components integrated on a semiconductor substrate.  相似文献   

12.
The artificial intelligence is applied to the simulation of the automotive air-conditioning system ( AACS) . According to the system's characteristics a model of AACS, based on neural network, is developed. Different control methods of AACS are discussed through simulation based on this model. The result shows that the neural-fuzzy control is the best one compared with the on-off control and conventional fuzzy control method. It can make the compartment's temperature descend rapidly to the designed temperature and the fluctuation is small.  相似文献   

13.
A novel 6 degrees of freedom (DOFs) wearable exoskeleton arm,ZJUESA,based on man-machine system is present- ed.It can be used in robot bilateral teleoperation as master arm with force-feedback.With introducing the revolute-prismatic-spherical (RPS) parallel mechanism and planetary gear mechanism,it is designed based on the anatomy of human upper-limb.With the sensors on this external mechanical structure,the human operator motion is detected and converted to the slave robot control command.Additionally the pneumatic system on it generates a force feedback by using hybrid fuzzy control.As a result,the human operator may have a feeling of doing the work directly.  相似文献   

14.
We obtain the boundedness of multilinear operator (BMO) of strongly singular integral operator (~T)A on Lp spaces based on the relation between commutators and multilinear operators. It is found that (~T)A is an (H1, L1) type operator, while TA is not.  相似文献   

15.
刘亚明 《科技信息》2007,(34):19-21
Influence of Au surfactant on the growth of Zn atom vacancies in ZnO nanostructures has been investigated by using first-principles slab calculations based on density functional theory.The adsorption of Au atoms on the Zn-terminated (0001)polar surface with a (2×2)surface unit cell is studied by using a standard supercell model.It is found that (1)the binding energies of Au atoms on (0001)-Zn increase and the most stable position of the Au atom is invariable; (2)on the (0001)surface,the preferred sites for Zn atom vacancy are on the first layer of Zn atoms; (3)Under the Au surfactant,the Zn atom vacancies become more difficult to form.  相似文献   

16.
Aimed at the actuality of Peoplep’s Liberation Army(PLA) army equipment maintenance, this paper develops equipment maintenance mode based on network,and focuses on the design of maintenance decision-making system. Analyzing maintenance weight is applied to making decision of repair level.The purpose of the research is introducing basic concept and setting up an equipment maintenance mode using military network.Maintenance mode based on network can reduce the costs,enhance the maintenance efficiency, and save the human resource and finance.  相似文献   

17.
Based on constructal theory,"disc-to-point" heat conduction is optimized by minimizing the entransy dissipation rate whereby a critical point is determined that distributes the high-conductivity material according to optimized radial or branch patterns.The results show that the critical point is determined by the product of the thermal conductivity ratio of the two materials and the volume fraction of the high-conductivity material allocated to the entire volume.The notion of optimal heat transfer performance can be attributed to the disc based on the entransy dissipation extremum principle.Comparing the results based on EDR minimization (entransy dissipation rate minimization) with those based on MTD minimization (maximum temperature difference minimization),one finds that the performance derived from the two optimization procedures are different.When the product of the thermal conductivity ratio and volume fraction is 30,the critical point of the former procedure is that for which the nondimensional radius of the disc equals 1.75,while that of the latter procedure is that for which this radius of the disc equals 2.18.Comparing heat transfer performances from the two procedures,the mean heat transfer temperature difference is decreased more for the former procedure thereby receiving an improved performance quota.  相似文献   

18.
19.
A nonlinear mathematical model of the injection molding process for electrohydraulic servo injection molding machine (IMM) is developed. It was found necessary to consider the characteristics of asymmetric cylinder for electrohydraulic servo IMM. The model is based on the dynamics of the machine including servo valve, asymmetric cylinder and screw, and the non-Newtonian flow behavior of polymer melt in injection molding is also considered. The performance of the model was evaluated based on novel approach of molding - injection and compress molding, and the results of simulation and experimental data demonstrate the effectiveness of the model.  相似文献   

20.
The fabrication of accurate prototype from CAD model directly in short time depends on the accurate tracking control and reference trajectory planning in (Laminated Object Manufacture) LOM application. An improvement on contour accuracy is acquired by the introduction of a tracking controller and a trajectory generation policy. A model of the X-Y positioning system of LOM machine is developed as the design basis of tracking controller. The ZPETC (Zero Phase Error Tracking Controller) is used to eliminate single axis following error, thus reduce the contour error. The simulation is developed on a Maltab model based on a retrofitted LOM machine and the satisfied result is acquired.  相似文献   

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