State complexity of basic operations on suffix-free regular languages

We investigate the state complexity of basic operations for suffix-free regular languages. The state complexity of an operation for regular languages is the number of states that are necessary and sufficient in the worst-case for the minimal deterministic finite-state automaton that accepts the language obtained from the operation. We establish the precise state complexity of catenation, Kleene star, reversal and the Boolean operations for suffix-free regular languages.     

Enhancements of two-stage stochastic decomposition

This paper presents some enhancements associated with stochastic decomposition (SD). Specifically, we study two issues: (a) Are there any conditions under which the regularized version of SD generates a unique solution? (b) Is there a way to modify the SD algorithm so that a user can trade-off solution times with solution quality? The second issue addresses the scalability of SD for very large scale problems for which computational resources may be limited and the user may be willing to accept solutions that are “nearly optimal”. We show that by using bootstrapping (re-sampling) the regularized SD algorithm can be accelerated without significant loss of optimality. We report computational results that demonstrate the viability of this approach.     

Several multi-criteria programming methods for classification

In this paper, we propose a general optimization-based model for classification. Then we show that some well-known optimization-based methods for classification, which were developed by Shi et al. [Data mining in credit card portfolio management: a multiple criteria decision making approac. In: Koksalan M, Zionts S, editors. Multiple criteria decision making in the new millennium. Berlin: Springer; 2001. p. 427–36] and Freed and Glover [A linear programming approach to the discriminant problem. Decision Sciences 1981; 12: 68–79; Simple but powerful goal programming models for discriminant problems. European Journal of Operational Research 1981; 7: 44–60], are special cases of our model. Moreover, three new models, MCQP (multi-criteria indefinite quadratic programming), MCCQP (multi-criteria concave quadratic programming) and MCVQP (multi-criteria convex programming), are developed based on the general model. We also propose algorithms for MCQP and MCCQP, respectively. Then we apply these models to three real-life problems: credit card accounts, VIP mail-box and social endowment insurance classification. Extensive experiments are done to compare the efficiency of these methods.     

减小IGBT模块功率损耗的研究和实现

研究影响IGBT功率损耗的相关因素,提出了降低IGBT功率损耗的设计方法,并在5kW光伏并网逆变器上实验,设计出了最合适的驱动门板电压、门板电阻和门极电容,使系统工作效率达到最大.     

Dynamic harmonic fields for surface processing

Harmonic fields have been shown to provide effective guidance for a number of geometry processing problems. In this paper, we propose a method for fast updating of harmonic fields defined on polygonal meshes, enabling real-time insertion and deletion of constraints. Our approach utilizes the penalty method to enforce constraints in harmonic field computation. It maintains the symmetry of the Laplacian system and takes advantage of fast multi-rank updating and downdating of Cholesky factorization, achieving both speed and numerical stability. We demonstrate how the interactivity induced by fast harmonic field update can be utilized in several applications, including harmonic-guided quadrilateral remeshing, vector field design, interactive geometric detail modeling, and handle-driven shape editing and animation transfer with a dynamic handle set.     

A multi-domain vertical alignment liquid crystal display to improve the V–T property

The voltage–transmittance (V–T) property is important for the liquid crystal displays (LCDs). In this work, we propose a sub-pixel structure with two common electrodes of a multi-domain vertical alignment (MVA) mode. The sub-pixel is divided into two sub-areas and different common electrode voltages are applied to it. The optimal voltage difference of the common electrodes between sub-area 1 and sub-area 2 is proposed. The simulated results on the plotted displays and the voltage–transmittance property of the LCD, which has 1:1 sub-area ratio, have been carried out. The results show that the structure can form MVA liquid crystal display mode, such as 8-domain VA mode. It can improve the V–T property at large oblique viewing angle and make the transmittance difference between the normal direction and the oblique direction viewing angle less than that of conventional 4-domain MVA mode.     

Epitomic Location Recognition

This paper presents a novel method for location recognition, which exploits an epitomic representation to achieve both high efficiency and good generalization. A generative model based on epitomic image analysis captures the appearance and geometric structure of an environment while allowing for variations due to motion, occlusions, and non-Lambertian effects. The ability to model translation and scale invariance together with the fusion of diverse visual features yields enhanced generalization with economical training. Experiments on both existing and new labeled image databases result in recognition accuracy superior to state of the art with real-time computational performance.     

Automatic detection of breast cancers in mammograms using structured support vector machines

Breast cancer is one of the most common cancers diagnosed in women. Large margin classifiers like the support vector machine (SVM) have been reported effective in computer-assisted diagnosis systems for breast cancers. However, since the separating hyperplane determination exclusively relies on support vectors, the SVM is essentially a local classifier and its performance can be further improved. In this work, we introduce a structured SVM model to determine if each mammographic region is normal or cancerous by considering the cluster structures in the training set. The optimization problem in this new model can be solved efficiently by being formulated as one second order cone programming problem. Experimental evaluation is performed on the Digital Database for Screening Mammography (DDSM) dataset. Various types of features, including curvilinear features, texture features, Gabor features, and multi-resolution features, are extracted from the sample images. We then select the salient features using the recursive feature elimination algorithm. The structured SVM achieves better detection performance compared with a well-tested SVM classifier in terms of the area under the ROC curve.     

Analysis of application patterns of Z-type MEMS microspring

In this paper, we design a Z-type microspring, which consists of several “Z” type micromechanical beams within mutual connection. With good mechanical performance and mature LIGA fabrication technology, Ni is chosen as the material of Z-type MEMS microspring. The mechanical properties of electroformed Ni have been tested by the Micro Hardness Tester, and the Young’s modulus is 219 GPa. Different from traditional springs, microsprings can be divided into three application patterns in direction x, y, and z to study. Applying the Castigliano second theorem of energy method in macro theory, the formulas used to calculate the spring constant of Z-type microspring in the directions of the three application patterns were derived, and verified by the ANSYS finite element method. Using the Tytron250 micro force test machine, the experiments of the Z-type microspring deformation properties were carried out. The spring constant, rupture force and rupture strength of Z-type microspring in direction y are 3821 N/m, 1.64 N and 1.61 GPa, respectively. The experimental results agree with the theoretical analysis. Based on the analysis above, the change laws of the spring constant of microspring in the three application patterns are summarized.     

智能阀门电动执行器的CAN总线研究

针对传统电动执行器存在的问题,设计了一种基于DSP2812的CAN总线智能阀门电动执行器.在介绍了阀门电动执行器的发展趋势和CAN总线技术的基础上,给出了电动执行器的硬件结构和软件设计方法.该电动执行器具有结构简单、性能稳定、精度高、调整方便、软件编程易于实现和可移植等特点.采用带CAN总线接口的TMS320F2812数字信号处理器,实现了智能阀门电动执行器实时通信的功能,提高了阀门电动执行器的智能化水平.