Showing papers by "Xi'an Jiaotong University published in 2003"
TL;DR: This paper formulate the stereo matching problem as a Markov network and solve it using Bayesian belief propagation to obtain the maximum a posteriori (MAP) estimation in the Markovnetwork.
Abstract: In this paper, we formulate the stereo matching problem as a Markov network and solve it using Bayesian belief propagation. The stereo Markov network consists of three coupled Markov random fields that model the following: a smooth field for depth/disparity, a line process for depth discontinuity, and a binary process for occlusion. After eliminating the line process and the binary process by introducing two robust functions, we apply the belief propagation algorithm to obtain the maximum a posteriori (MAP) estimation in the Markov network. Other low-level visual cues (e.g., image segmentation) can also be easily incorporated in our stereo model to obtain better stereo results. Experiments demonstrate that our methods are comparable to the state-of-the-art stereo algorithms for many test cases.
1,272 citations
TL;DR: In this paper, the authors attribute this to their similar family systems, which generate strong disincentives to raise daughters while valuing adult women's contributions to the household, and propose to increase the flexibility of the kinship system such that daughters and sons can be perceived as being more equally valuable.
Abstract: Son preference has persisted in the face of sweeping economic and social changes in China, India, and the Republic of Korea. The authors attribute this to their similar family systems, which generate strong disincentives to raise daughters while valuing adult women's contributions to the household. Urbanization, female education, and employment can only slowly change these incentives without more direct efforts by the state and civil society to increase the flexibility of the kinship system such that daughters and sons can be perceived as being more equally valuable. Much can be done to this end through social movements, legislation, and the mass media.
783 citations
TL;DR: This paper presents a general framework for the study of fuzzy rough sets in which both constructive and axiomatic approaches are used and the connections between fuzzy relations and fuzzy rough approximation operators are examined.
568 citations
TL;DR: In this article, the concept of magnetocaloric effect is explained and the development of the magnetic material, magnetic refrigeration cycles, magnetic field and the regenerator of room temperature magnetic refrigerators is introduced.
Abstract: Room temperature magnetic refrigeration is a new highly efficient and environmentally protective technology. Although it has not been maturely developed, it shows great applicable prosperity and seems to be a substitute for the traditional vapor compression technology. In this paper, the concept of magnetocaloric effect is explained. The development of the magnetic material, magnetic refrigeration cycles, magnetic field and the regenerator of room temperature magnetic refrigeration is introduced. Finally some typical room temperature magnetic refrigeration prototypes are reviewed.
497 citations
TL;DR: Optimal fusion rules based on the best linear unbiased estimation (BLUE), the weighted least squares (WLS), and their generalized versions are presented for cases with complete, incomplete, or no prior information.
Abstract: This paper deals with data (or information) fusion for the purpose of estimation. Three estimation fusion architectures are considered: centralized, distributed, and hybrid. A unified linear model and a general framework for these three architectures are established. Optimal fusion rules based on the best linear unbiased estimation (BLUE), the weighted least squares (WLS), and their generalized versions are presented for cases with complete, incomplete, or no prior information. These rules are more general and flexible, and have wider applicability than previous results. For example, they are in a unified form that is optimal for all of the three fusion architectures with arbitrary correlation of local estimates or observation errors across sensors or across time. They are also in explicit forms convenient for implementation. The optimal fusion rules presented are not limited to linear data models. Illustrative numerical results are provided to verify the fusion rules and demonstrate how these fusion rules can be used in cases with complete, incomplete, or no prior information.
482 citations
18 Jun 2003
TL;DR: This work is inspired by recent progress on natural image statistics that the priors of image primitives can be well represented by examples and proposes a Bayesian approach to image hallucination, where primal sketch priors are constructed and used to enhance the quality of the hallucinated high resolution image.
Abstract: We propose a Bayesian approach to image hallucination. Given a generic low resolution image, we hallucinate a high resolution image using a set of training images. Our work is inspired by recent progress on natural image statistics that the priors of image primitives can be well represented by examples. Specifically, primal sketch priors (e.g., edges, ridges and corners) are constructed and used to enhance the quality of the hallucinated high resolution image. Moreover, a contour smoothness constraint enforces consistency of primitives in the hallucinated image by a Markov-chain based inference algorithm. A reconstruction constraint is also applied to further improve the quality of the hallucinated image. Experiments demonstrate that our approach can hallucinate high quality super-resolution images.
444 citations
TL;DR: In this paper, a continuous tubular supercritical water gasification system is proposed to realize the overall high-pressure continuous reaction by operating the valves, which can be used for solution or slurry materials gasification without drying.
331 citations
TL;DR: In this paper, the deposition characteristics of the particle in cold spray were studied by the examination of the microstructure evolution of the deposited spot and coating, and the effects of the gas type and temperature on the deposition behavior were examined.
Abstract: Titanium coating was deposited by cold spraying process using nitrogen and helium gases under different temperatures and pressures. The deposition characteristics of the particle in cold spray were studied by the examination of the microstructure evolution of the deposited spot and coating. The effects of the gas type and temperature on the deposition behavior were examined. The microstructure was examined using optical microscopy and scanning electron microscopy. It was found that the pattern of a sprayed spot in cold spray presents a conical shape. The deposition efficiency of spray particles increases with the increase in gas temperature. Two distinguishable top and inner regions exist in the spot deposit and coating, which are characterized by the porous and dense microstructures. The dense microstructure results from the accumulative effect of tamping on the top porous region by the successive impact of following particles. The tamping effect has great influence on the microstructure of the coating in cold spray.
305 citations
TL;DR: In this paper, the axisymmetric large deflection bending of a functionally graded circular plate under mechanical, thermal and combined thermal-mechanical loadings, respectively, was investigated.
295 citations
TL;DR: In this paper, the morphology, elemental composition and phase components of the titania-based films were investigated as a function of the electrolytes composition and the applied voltage (in the range of 200-500 V).
Abstract: Titania-based films on titanium were formed by micro-arc oxidation in electrolytic solutions containing sodium carbonate, sodium phosphate, acetate monohydrate and β-glycerophosphate disodium salt pentahydrate using a pulse power supply. The morphology, elemental composition and phase components of the films were investigated as a function of the electrolytes composition and the applied voltage (in the range of 200–500 V). In vitro bioactivity of the films was evaluated in a most commonly used simulated body fluid as proposed by Kokubo et al. The results showed that the films were porous with 1–8 μm pores and nano-crystallized, without apparent interface to the titanium substrates. The phase components of the films could be anatase, rutile, CaTiO 3 , β-Ca 2 P 2 O 7 and α-Ca 3 (PO 4 ) 2 , strongly depending on the electrolytes composition and the applied voltage. The pore size and the content of Ca and P tended to increase with the applied voltage. Among the prepared titania-based films, only the film containing CaTiO 3 , β-Ca 2 P 2 O 7 and α-Ca 3 (PO 4 ) 2 could induce an apatite layer on its surface, exhibiting bioactivity. The bioactive response of the micro-arc oxidized films to the structural factors and the apatite-induced mechanism were discussed.
243 citations
TL;DR: A new kind of knowledge reduction is introduced called a maximum distribution reduct, which preserves all maximum decision classes and overcomes the drawback of the possible reduct that the derived decision rules may be incompatible with the ones derived from the original system.
Abstract: This article deals with approaches to knowledge reductions in inconsistent information systems (ISs). The main objective of this work was to introduce a new kind of knowledge reduction called a maximum distribution reduct, which preserves all maximum decision classes. This type of reduction eliminates the harsh requirements of the distribution reduct and overcomes the drawback of the possible reduct that the derived decision rules may be incompatible with the ones derived from the original system. Then, the relationships among the maximum distribution reduct, the distribution reduct, and the possible reduct were discussed. The judgement theorems and discernibility matrices associated with the three reductions were examined, from which we can obtain approaches to knowledge reductions in rough set theory (RST). © 2003 Wiley Periodicals, Inc.
15 Mar 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a previous model was modified to present quantitative relationships between the yield strengths of the alloys and the sizes, volume percentages of precipitates, related to aging temperature and aging time as well as alloy compositions, while the strengthening of the precipitates was coupled with the whole evolution process.
Abstract: For the heat-treatable aluminum alloys containing plate or rod/needle-shaped precipitates, a previous model was modified to present quantitative relationships between the yield strengths of the alloys and the sizes, volume percentages of precipitates, related to aging temperature and aging time as well as alloy compositions, while the strengthening of the precipitates was coupled with the whole evolution process, i.e. nucleation, growth and coarsening, of the precipitates. It was found that the aging yield strengths have been well predicted by the model for a series of aged Al–Cu binary alloys, 6061 alloys and Al–Zn–Mg alloys. It was also experimentally proved that the model was suitable to evaluate the aging strengthening of the precipitates for an Al–Cu–Mg alloy and an Al–Mg–Si alloy. Furthermore, a detailed discussion has been made to the variation of aspect ratio of precipitates, relative to its strengthening response, with aging parameters and alloy compositions.
TL;DR: In this article, the authors gave a brief account of the well-known solution for a line crack in a magnetoelectroelastic medium and derived the asymptotic form of the strain energy density function that was first given for the piezoelectric BaTiO 3 -CoFe 2 O 4 composite.
29 Sep 2003
TL;DR: In this paper, a time-interval based control strategy is adopted that decomposes a daily load forecast into several sequential load levels, and a genetic algorithm based procedure is used to determine both the load level partitioning and the dispatch scheduling.
Abstract: A strategy for volt/VAr control in distribution systems is described. The aim is to determine optimum dispatch schedules for on-load tap changer (OLTC) settings at substations and all shunt capacitor switching based on the day-ahead load forecast. To reduce switching operations for OLTC at substations, a time-interval based control strategy is adopted that decomposes a daily load forecast into several sequential load levels. A genetic algorithm based procedure is used to determine both the load level partitioning and the dispatch scheduling. The proposed strategy minimises the power loss and improves the voltage profile for a whole day across the whole system, whilst ensuring that the number of switching operations is less than the maximum daily allowance. A comparison of numerical studies and their associated results illustrates both the feasibility and the effectiveness of the proposed strategy.
TL;DR: In this paper, the relationship between the magnetic field and the complex shear modulus of MR materials in the pre-yield regime is investigated using oscillatory rheometry techniques.
TL;DR: It is pointed out that Zhou's encryption scheme is not secure enough from strict cryptographic viewpoint because the dynamical degradation of the computerized piecewise linear chaotic map employed by Zhou et al. induces many weak keys to cause large information leaking of the plaintext.
TL;DR: In this paper, the Bingham model of MR damper is introduced, and the formula relating the yielding shear stress and the control current of MR dampers is put forward that matches the experimental data.
Abstract: Semi-active control of buildings and structures with magnetorheological (MR) dampers for earthquake hazard mitigation represents a relatively new research area. In this paper, the Bingham model of MR damper is introduced, and the formula relating the yielding shear stress and the control current of MR dampers is put forward that matches the experimental data. Then an on-line real-time control method for semi-active control of structures with MR dampers is proposed. This method considers the time-delay problem of semi-active control, which can solve distortion of the responses of structures. Finally, through a numerical example of a three-storey reinforced concrete structure, a comparison is made between controlled structure and uncontrolled structure. The calculated results show that MR dampers can reduce the seismic responses of structures effectively. Moreover, the on-line real-time control method is compared with the traditional elastoplastic time-history analysis method, and the efficacy of the on-line real-time control method is demonstrated. In addition, the Levenberg–Marquardt algorithm is used to train the on-line control neural network, and studies show that the algorithm has a very fast convergence rate.
13 Jul 2003
TL;DR: It is rigorously proved that UC is indeed an NP complete problem, and therefore it is impossible to develop an algorithm with polynomial computation time to solve it.
Abstract: Lagrangian relaxation (LR) and general mixed integer programming (MIP) are two main approaches for solving unit commitment (UC) problems. This paper compares the LR and the state of art general MIP method for solving UC problems based on performance analysis and numerical testing. In this paper we have rigorously proved that UC is indeed an NP complete problem, and therefore it is impossible to develop an algorithm with polynomial computation time to solve it. In comparison with the general MIP methods, the LR methodology is more scaleable and efficient to obtain near optimal schedules for large scale and hard UC problems at the cost of a small percentage of deviation from the optimal solution. In particular, solving hydro generation subproblems within the LR framework can take advantages of both LR and general MIP methods and provide a synergetic combination of both approaches.
TL;DR: In this article, the authors proposed to use the strain energy density function as a failure criterion for a BaTiO3-CoFe2O4 two-phase composite, where the poling directions introduced magnetically and electrically can be different in addition to those for the applied magnetic and electric field.
TL;DR: The basic reproduction number R0 is proved to be a sharp threshold which completely determines the global dynamics and the outcome of the disease.
Abstract: Heesterbeek and Metz [J. Math. Biol. 31 (1993) 529] derived an expression for the saturating contact rate of individual contacts in an epidemiological model. In this paper, the SEIR model with this saturating contact rate is studied. The basic reproduction number R0 is proved to be a sharp threshold which completely determines the global dynamics and the outcome of the disease. If R0 1, there exists a unique endemic equilibrium which is globally stable and the disease persists at an endemic equilibrium state if it initially exists. The contribution of the saturating contact rate to the basic reproduction number and the level of the endemic equilibrium is also analyzed.
01 Dec 2003
TL;DR: A novel methodology called a reference model approach to stability analysis of neural networks is proposed, to study a neural network model with reference to other related models, so that different modeling approaches can be combinatively used and powerfully cross-fertilized.
Abstract: In this paper, a novel methodology called a reference model approach to stability analysis of neural networks is proposed. The core of the new approach is to study a neural network model with reference to other related models, so that different modeling approaches can be combinatively used and powerfully cross-fertilized. Focused on two representative neural network modeling approaches (the neuron state modeling approach and the local field modeling approach), we establish a rigorous theoretical basis on the feasibility and efficiency of the reference model approach. The new approach has been used to develop a series of new, generic stability theories for various neural network models. These results have been applied to several typical neural network systems including the Hopfield-type neural networks, the recurrent back-propagation neural networks, the BSB-type neural networks, the bound-constraints optimization neural networks, and the cellular neural networks. The results obtained unify, sharpen or generalize most of the existing stability assertions, and illustrate the feasibility and power of the new method.
TL;DR: In this paper, the pressure drop and boiling heat transfer characteristics of steam-water two-phase flow were studied in a small horizontal helically coiled tubing once-through steam generator, which was constructed of a 9mm ID 1Cr18Ni9Ti stainless steel tube with 292mm coil diameter and 30mm pitch.
TL;DR: The results showed that the activity of trypsin decreased with increasing ultrasound power from 100 to 500 W or extending the irradiation time from 1 to 20 min, and this effect could be enhanced via aerating the solution for a duration 10 min at 300 W.
TL;DR: In this paper, a computational fluid dynamics (CFD) program FLUENT has been used to predict the fluid flow distribution in plate-fin heat exchangers, and two modified headers with a two-stage distribution structure are proposed and simulated.
TL;DR: In this article, a mathematical SIS model with pulse vaccination is formulated and the dynamical behavior of the model is studied, and the basic reproductive number R"0 is defined.
06 Apr 2003
TL;DR: This paper combines linear spun coding and nonnegative matrix factorization into sparse non-negative matrixfactorization, which can learn much sparser representation via imposing sparseness constraints explicitly and can learn parts-based representation via fully multiplicative updates.
Abstract: This paper combines linear spun coding and nonnegative matrix factorization into sparse non-negative matrix factorization. In contrast to non-negative matrix factorization, the new model can learn much sparser representation via imposing sparseness constraints explicitly; in contrast to a close model -non-negative sparse coding, the new model can learn parts-based representation via fully multiplicative updates because of adapting a generalized Kullback-Leibler divergence instead of the conventional mean error for approximation error. Experiments on MIT-CBCL training facts data demonstrate the effectiveness of the proposed method.
TL;DR: In this article, the authors proposed practical and simple methods, which involve applying current or voltage perturbation to the dc side of distributed power systems then only measuring the amplitude of two currents or voltages in order to monitor the stability margin.
Abstract: In multi-module power electronics systems, especially DC distributed power systems, the small-signal stability issues are often dealt with by employing Middlebrook's impedance criterion. However, for on-line system stability margin monitoring, directly measuring impedance of the source and load subsystems then making quantitative comparisons is too complicated and difficult. This paper proposes practical and simple methods, which involve applying current or voltage perturbation to the dc side of distributed power systems then only measuring the amplitude of two currents or voltages in order to monitor the stability margin. For both methods (current perturbation and voltage perturbation), an implementation approach that does not employ external voltage or current perturbation source is also presented. All these methods and approaches are equivalent to the impedance measuring and comparing method based on the impedance criterion with different forbidden regions. A comparative evaluation of each method and its corresponding implementation approach is provided.
TL;DR: In this paper, the age hardening in Cu-3.2Ni-0.75Si alloy at 723 K was studied by means of transmission electron microscope (TEM) and X-ray diffraction.
TL;DR: In this article, the relative air-gap-specific permeance distribution function by Schwarz-Christoffel transformation, considering the effect of slotting, is derived, and the instantaneous electromagnetic torque is computed, which underpins the quantitative analysis of torque ripple and the pulsation induced by commutation.
Abstract: This paper derives the relative air-gap-specific permeance distribution function by Schwarz-Christoffel transformation, considering the effect of slotting. Neglecting the iron saturation, and employing the analytical algorithm for partial differential equations, efficient and effective analytical calculations of no-load air-gap magnetic field distribution, armature field distribution, and phase electromotive force (EMF), are demonstrated, considering the stator slots. Subsequently, based on the main circuit topology of a brushless DC motor (BLDCM), the field-circuit coupling model is constructed for the motor, and then the phase current waveforms and load air-gap magnetic field distribution at any time are determined. Consequently, the instantaneous electromagnetic torque is computed, which underpins the quantitative analysis of torque ripple and the pulsation induced by commutation. Hence, the present work paves the way to precise prediction of the motor's performance and acoustic noise. It is a powerful tool for the design of surface permanent magnet brushless DC motors.
TL;DR: In this article, the existence of positive solutions to the nonlinear boundary value problem was studied and at least one positive solution if f is either superlinear or sublinear by applying the fixed point theorem in cones.