作者：
Merkle, MilanUniversity of Belgrade
Faculty of Electrical Engineering Department of Applied Mathematics 11120 Belgrade P. O. Box 35-54 Serbia
We consider necessary and sufficient conditions for the convexity of a function x f′(x) in terms of some properties of the associated function of two variables F (x,y) = (f (y) - f(x))/(y - x)- In particular, we prov...
详细信息
Many important algorithms can be described by n-dimensional uniform recurrences. The computations are then indexed by integral vectors of length n and the data dependencies between computations can be described by the...
详细信息
Many important algorithms can be described by n-dimensional uniform recurrences. The computations are then indexed by integral vectors of length n and the data dependencies between computations can be described by the difference vector of the corresponding indexes which are independent of the indexes. This paper addresses the following optimization problem: Given an n-dimensional uniform recurrence whose computation indexes are mapped by a linear function onto the processors of an array processor embedded in k-space (1 &le k &le n). Find an optimal linear function for the computation indexes. We study a continuous approximation of this problem by passing from linear to quasi-linear timing functions. The resultant problem formulation is then a quadratic programming problem which can be solved by standard algorithms for quadratic or general nonlinear optimization problems. We demonstrate the effectiveness of our approach by several nontrivial test examples.
An analysis of a discrete time-frequency distribution yields a new periodic wide band probing signal for use in unknown system identification. The derivation is based on the mathematical properties of the discrete Wig...
详细信息
The exact (1+1)\|dimensional similarity solutions of the Broadwell model are studied in a concise way. A new type of exact (1+1)\|dimensional similarity solutions of the Broadwell model are obtained. The conclusion th...
详细信息
The exact (1+1)\|dimensional similarity solutions of the Broadwell model are studied in a concise way. A new type of exact (1+1)\|dimensional similarity solutions of the Broadwell model are obtained. The conclusion that one\|dimensional Broadwell model cannot have multi\|dimensional similarity solutions is proved and the proof is simplified.
Pulse propagation in random media is studied by solving the two-frequency radiative transfer equation and transforming the solution into the time domain via Fourier transforms. We briefly review several known techniqu...
详细信息
Pulse propagation in random media is studied by solving the two-frequency radiative transfer equation and transforming the solution into the time domain via Fourier transforms. We briefly review several known techniques of solving the radiative transfer equation and describe a simple and effective finite element method which allows for the investigation of pulse propagation through highly anisotropic media. Specifically, pulse delay and broadening are calculated by solving the radiative transfer equation with empirically determined coefficients for fog and rain layers. In addition, first-order multiple scattering and diffusion approximations are compared to the solutions of the radiative transfer equation, and are found to be useful depending on the values of the single-scattering albedo, optical depth and asymmetry parameter.
We give a formal definition of dissipative systems that is considerably more general than earlier definitions. The measured output is irrelevant in this formulation. The key component of dissipation is an appropriate ...
详细信息
We give a formal definition of dissipative systems that is considerably more general than earlier definitions. The measured output is irrelevant in this formulation. The key component of dissipation is an appropriate work rate. We also define cycle-dissipation and show how it can be used to obtain a suitable work rate. Using this idea, we propose a new work rate for the Preisach hysteresis model, and demonstrate dissipativity with respect to this rate. The Preisach model describes the dynamics of many "smart materials" such as shape memory alloys. This new type of dissipativity will be beneficial in the design of position controllers for SMA.
We explore the transform coefficients of various fractal-based schemes for statistical dependence and exploit correlations to improve the compression capabilities of these schemes. In most of the standard fractal-base...
详细信息
We explore the transform coefficients of various fractal-based schemes for statistical dependence and exploit correlations to improve the compression capabilities of these schemes. In most of the standard fractal-based schemes, the transform coefficients exhibit a degree of linear dependence that can be exploited by using an appropriate vector quantizer such as the LBG algorithm. Additional compression is achieved by lossless Huffman coding of the quantized coefficients.
Consider situations where the depth at each point in the scene is multi-valued due to the presence of a virtual image semi-reflected by a transparent surface. The semi-reflected image is linearly superimposed on the i...
详细信息
Consider situations where the depth at each point in the scene is multi-valued due to the presence of a virtual image semi-reflected by a transparent surface. The semi-reflected image is linearly superimposed on the image of the object that is behind the transparent surface. A novel approach is proposed for the recovery of the superimposed layers. By searching for the images in which either of the objects (layers) is focused, the transparent areas are detected and an estimate of the depth map of each layer is obtained. As a result of the focusing, an initial separation of the layers is achieved. The separation is enhanced via mutual blurring of the perturbing components in the images, based on the depths estimate and the parameters of the imaging system.
The results for a height and flow-dependent model for turbulent viscosity are reported. This model is developed to explain the generation of sand waves in tidal seas and resolves the problem of excitation of very long...
详细信息
The results for a height and flow-dependent model for turbulent viscosity are reported. This model is developed to explain the generation of sand waves in tidal seas and resolves the problem of excitation of very long waves in sand wave formation, because it leads to damping of the long waves and gives a finite separation between the most excited mode and the zero mode. For parameter settings within a physically realistic range, a linear analysis of the resulting system yields a first excited mode whose wavelength is similar to the characteristic wavelength of sand waves observed in nature. This result can be the starting point for a nonlinear analysis of the system.
An analysis of a discrete time-frequency distribution yields a new periodic wide band probing signal for use in unknown system identification. The derivation is based on the mathematical properties of the discrete Wig...
详细信息
An analysis of a discrete time-frequency distribution yields a new periodic wide band probing signal for use in unknown system identification. The derivation is based on the mathematical properties of the discrete Wigner distribution. Like the continuous distribution, the discrete version also satisfies the covariance property, meaning transformations in the time-frequency plane are equivalent to transformations in the time domain. By utilizing this property, the linearly swept frequency measurement is extended to discrete, periodic signals. The resulting probing signal possesses favorable characteristics such as a short illumination time requirement and good resistance to noise. The performance of the proposed probing method is compared with m-sequence methods and chirp signal methods.
暂无评论