抗噪Roberts算子边沿检测器

图像边缘检测是图像分割、目标识别、区域形态提取等图像分析技术的基础。边沿检测的软件实现有很多方法,但其一般无法保证在低成本计算平台上的实时性。因此文中基于形态学滤波和Roberts边沿检测算法提出一组数字电路,用以实现低成本、实时图像边沿检测器。文中还对比了Roberts算子的Matlab上实现和硬件实现的实际效果,发现实际硬件的边沿检测精度更高,噪声更多,必须采用去噪电路。该检测器消耗ALTERA-EP4CE115中2139个逻辑单元,每秒可处理30帧分辨率为640*480的RGB图像。     

Collision and intersection detection of two ruled surfaces using bracket method

Collision and intersection detection of surfaces is an important problem in computer graphics and robotic engineering. A key idea of our paper is to use the bracket method to derive the necessary and sufficient conditions for the collision of two ruled surfaces. Then the numerical intersection curve can be characterized. The cases for two bounded ruled surfaces are also discussed.     

Real time 3D simulation for nose surgery and automatic individual prosthesis design

This paper presents an intuitive nose surgery planning and simulation system, using 3D laser scan image and lateral X-ray image, to provide high quality prediction of the postoperative appearance, and design the patient specific prosthesis model automatically. After initial registration, the internal surface of soft tissue at the nose region was generated by the statistical data for soft tissue thickness adapted by the individual thickness information from the X-ray image. Then, the sketch contour of the 3D scan data on the lateral X-ray image was modified manually or adjusted automatically according to some aesthetic statistical data, to drive the simulation in real time by the state-of-the-art Laplacian surface deformation method. When satisfied with the 3D postoperative appearance, the deformation was mapped to the internal surface of soft tissue, and the change before and after simulation was utilized to generate the patient specific prosthesis model automatically. The surgeons who used the system confirmed that this planning system is attractive and has potential for daily clinical practice.     

Low-frequency wide-band hybrid energy harvester based on piezoelectric and triboelectric mechanism

Recently,hybrid energy harvester has been considered as an attractive potential approach to response the worldwide energy crisis due to the combination of advantages from different harvesting mechanism.In this paper,a novel low-frequency wide-band hybrid energy harvester based on piezoelectric and triboelectric mechanism is presented and systematically studied including structural design,fabrication process,working principle simulation and measurement.With a vibrational excitation,the polyvinylidene fluoride(PVDF) cantilevers will vibrate and impact the polydimethylsiloxane(PDMS) film on the substrate,producing a piezoelectric output as well as a triboelectric output.The structural parameters of each cantilever are optimized using finite element simulation,and the well-designed PVDF cantilevers with controllable PDMS mass not only reduce the device working frequency but also enlarge the bandwidth.Under a sweep-frequency test,three voltage peaks induced by the piezoelectric part are observed at 15,32.5 and 47.5 Hz,with the value of 320,288 and 264 mV,respectively.With the combined triboelectric part,a 20 V peak-peak voltage is generated at 15 Hz.The electrical driving ability of this hybrid energy harvester also has been demonstrated by lighting up a commercial light emitting diode(LED).     

Generalized Adjusted Rand Indices for cluster ensembles

In this paper, Adjusted Rand Index (ARI) is generalized to two new measures based on matrix comparison: (i) Adjusted Rand Index between a similarity matrix and a cluster partition (ARImp), to evaluate the consistency of a set of clustering solutions with their corresponding consensus matrix in a cluster ensemble, and (ii) Adjusted Rand Index between similarity matrices (ARImm), to evaluate the consistency between two similarity matrices. Desirable properties of ARI are preserved in the two new measures, and new properties are discussed. These properties include: (i) detection of uncorrelatedness; (ii) computation of ARImp/ARImm in a distributed environment; and (iii) characterization of the degree of uncertainty of a consensus matrix. All of these properties are investigated from both the perspectives of theoretical analysis and experimental validation. We have also performed a number of experiments to show the usefulness and effectiveness of the two proposed measures in practical applications.     

Identification of Breast Cancer Prognosis Markers via Integrative Analysis

In breast cancer research, it is of great interest to identify genomic markers associated with prognosis. Multiple gene profiling studies have been conducted for such a purpose. Genomic markers identified from the analysis of single datasets often do not have satisfactory reproducibility. Among the multiple possible reasons, the most important one is the small sample sizes of individual studies. A cost-effective solution is to pool data from multiple comparable studies and conduct integrative analysis. In this study, we collect four breast cancer prognosis studies with gene expression measurements. We describe the relationship between prognosis and gene expressions using the accelerated failure time (AFT) models. We adopt a 2-norm group bridge penalization approach for marker identification. This integrative analysis approach can effectively identify markers with consistent effects across multiple datasets and naturally accommodate the heterogeneity among studies. Statistical and simulation studies demonstrate satisfactory performance of this approach. Breast cancer prognosis markers identified using this approach have sound biological implications and satisfactory prediction performance.     

汉语同语的功能特点与英译策略

以北大语料库(CCL)为例,分析论述汉语同语的功能特点.除了和英语同语一样可以表示强调以外,它们还具有转折、让步和赞誉的功能.对汉语同语进行英译时,应通过“理解-传递-体现”三个阶段实现功能对等.对表强调功能的单举式同语,可以保留其语言形式;对具有转折、让步和赞誉功能以及表强调功能的对举式同语,则应弃形式、保功能.     

受控振动柱体对波浪影响的数值模拟研究

以不可压缩黏性流体的Navier-Stokes方程为控制方程,采用RNG k-ε湍流模型,利用VOF方法追踪运动的自由表面的方法,建立了三维数值波浪与振动柱体相互作用的模型.基于经典绕射理论验证了波浪绕固定柱体传播的数值模型的可靠性,再采用动边界技术赋予柱体振动规律,研究受控振动柱体对波浪传播的影响,并通过控制柱体初始振动相位变化,系统地给出了在柱体振动的不同初始相位下柱体前后波浪变化的规律.     

曹妃甸新区水资源供需预测分析

依据曹妃甸新区国民经济规划资料,对其未来需水量进行了全面预测,并结合水资源配置规划方案,对各水平年的水资源供需进行了预测分析,以期为今后曹妃甸新区合理开发和有效利用水资源提供了科学依据。     

国债市场的流动性套利及其实证检验

提出了一种在保持一定流动性风险的情况下构建国债套利组合的方法,应用线性规划技术,将国债的持有期风险因素引入到约束条件中,进而求解出实现最大期初套利的国债投资组合。通过对我国上交所25种债券的实证检验,发现套利收益与组合的持有期风险成正比,与流动性指标成反比,这证明了在考虑债券流动性风险的情况下,进行债券套利操作不一定会带来可观的收益。