黄土崾岘地段输油气管道敷设技术

通过对陕京三线输气管道工程在陕北境内的十几处黄土崾岘地貌和地质特征进行分析,结合工程实际,以下部为2∶8灰土,上部为3∶7灰土的崾岘加固为模型,对此种崾岘拓宽技术进行受力计算,并与传统的下部为3∶7灰土,上部为2∶8灰土的崾岘加固技术进行沉降数值比较,得出现行的加固处理技术沉降小且工程经济效益好。此外,提出了黄土崾岘拓...     

Image mosaicking for polyhedral scene and in particular singly visible surfaces

Image mosaic construction is about stitching together a number of images about the same scene to construct a single image with a larger field of view. The majority of the previous work was rooted at the use of a single image-to-image mapping termed planar homography for representing the imaged scene. However, the mapping is applicable only to cases where the imaged scene is either a single planar surface, or very distant from the cameras, or imaged under a pure rotation of the camera, and that greatly limits the range of applications of the mosaicking methods. This paper presents a novel mosaicking solution for scenes that are polyhedral (thus consisting of multiple surfaces) and that are pictured possibly in closed range of the camera. The solution has two major advantages. First, it requires only a few correspondences over the entire scene, not correspondences over every surface patch in it to work. Second, it conquers a seemingly impossible task—warping image data of surfaces that are visible in only one of the input images, which we refer to as the singly visible surfaces, to another viewpoint to constitute the mosaic there. We also provide a detail analysis of what determines whether a singly visible surface could be mosaicked or not. Experimental results on real image data are presented to illustrate the performance of the method.     

The impact of misregistration on SRTM and DEM image differences

Image differences between Shuttle Radar Topography Mission (SRTM) data and other Digital Elevation Models (DEMs) are often performed for either accuracy assessment or for estimating vegetation height across the landscape. It has been widely assumed that the effect of sub-pixel misregistration between the two models on resultant image differences is negligible, yet this has not previously been tested in detail. The aim of this study was to determine the impact that various levels of misregistration have on image differences between SRTM and DEMs. First, very accurate image co-registration was performed at two study sites between higher resolution DEMs and SRTM data, and then image differences (SRTM–DEM) were performed after various levels of misregistration were systematically introduced into the SRTM data. It was found that: (1) misregistration caused an erroneous and dominant correlation between elevation difference and aspect across the landscape; (2) the direction of the misregistration defined the direction of this erroneous and systematic elevation difference; (3) for sub-pixel misregistration the error due solely to misregistration was greater than, or equal to the true difference between the two models for substantial proportions of the landscape (e.g., greater than 33% of the area for a half-pixel misregistration); and (4) the strength of the erroneous relationship with aspect was enhanced by steeper terrain. Spatial comparisons of DEMs were found to be sensitive to even sub-pixel misregistration between the two models, which resulted in a strong erroneous correlation with aspect. This misregistration induced correlation with aspect is not likely specific to SRTM data only; we expect it to be a generic relationship present in any DEM image difference analysis.     

基于Pro/E的远程零件参数化设计系统研究

提出了一种远程设计机械零部件的新方案.利用VC+ +对Pro/E进行二次开发,将开发的程序封装成COM组件,利用Pro/E进行参数化建模,通过ASP技术调用COM组件实现远程参数化设计.以斜齿圆柱齿轮为例说明机械零部件远程设计系统的实现过程.     

有机磷水解酶生物传感器载体固定化酶的研究

有机磷水解酶（OPH）传感器作为检测农产品中农药残留的新型检测装置,其酶的固定化对OPH传感器的灵敏度和稳定性有重要的影响。研究了几种酶固定化载体、孔径大小、固定方式、固定方法（试剂组成）对传感器pH值的影响。结果显示：采用孔径为0.45μm的硝酸纤维素膜制备固定化酶片的pH值要大于其余几种;采用浸泡方式制备固定化酶片的pH值明显大于传统的滴定法;采用牛血清白蛋白（BSA）、戊二醛交联固定的效果优于酶直接吸附法和BSA固定法,且当戊二醛体积分数为2.5％,BSA为10％时,酶固定化效果最好。     

CCD摄像机标定

在基于单目视觉的农业轮式移动机器人自主导航系统中,CCD摄像机标定是农业轮式移动机器人正确和安全导航的前提和关键。摄像机标定确立了地面某点的三维空间坐标与计算机图像二维坐标之间的对应关系,机器人根据该关系计算出车体位姿值自主导航。因此,根据CCD摄像机针孔成像模型,利用大地坐标系中平面模板上已知的各点坐标,建立与计算机图像空间中各对应像素值之间的关系方程组,在Matlab环境下拟合出摄像机各内外参数。实验结果表明：该方法可以正确完成CCD摄像机标定。     

Network‐based method for detecting dysregulated pathways in glioblastoma cancer

The knowledge on the biological molecular mechanisms underlying cancer is important for the precise diagnosis and treatment of cancer patients. Detecting dysregulated pathways in cancer can provide insights into the mechanism of cancer and help to detect novel drug targets. Based on the wide existing mutual exclusivity among mutated genes and the interrelationship between gene mutations and expression changes, this study presents a network‐based method to detect the dysregulated pathways from gene mutations and expression data of the glioblastoma cancer. First, the authors construct a gene network based on mutual exclusivity between each pair of genes and the interaction between gene mutations and expression changes. Then they detect all complete subgraphs using CFinder clustering algorithm in the constructed gene network. Next, the two gene sets whose overlapping scores are above a specific threshold are merged. Finally, they obtain two dysregulated pathways in which there are glioblastoma‐related multiple genes which are closely related to the two subtypes of glioblastoma. The results show that one dysregulated pathway revolving around epidermal growth factor receptor is likely to be associated with the primary subtype of glioblastoma, and the other dysregulated pathway revolving around TP53 is likely to be associated with the secondary subtype of glioblastoma.Inspec keywords: cancer, tumours, drugs, brain, neurophysiology, genetic algorithms, genetics, skin, proteins, molecular biophysics, genomics, patient diagnosis, molecular configurationsOther keywords: network‐based method, dysregulated pathways detection, glioblastoma cancer, biological molecular mechanisms, precise diagnosis, cancer patient treatment, drug targets, mutual exclusivity, mutated genes, gene mutations, expression changes, expression data, CFinder clustering algorithm, constructed gene network, gene sets, overlapping scores, glioblastoma‐related multiple genes, epidermal growth factor receptor, TP53, secondary subtype     

A simple approach to find optimal topology of a continuum with tension-only or compression-only material

The material-replacement method is presented to improve the efficiency of topology optimization of a continuum structure with tension-only or compression-only material. Traditionally, a structure with tension-only or compression-only material should be considered as nonlinear in finite element analysis and many times of reanalysis are required to obtain the accurate physical fields for the update of the design variables in optimization. To improve the efficiency of structural optimization, the material-replacement method is proposed, in which the original tension/compression only material is replaced with an isotropic material with the same effective elasticity. The method contents two major ideas. One is the structural reanalysis for nonlinearity of material is put into the global iteration of optimization. The other is that the local stiffness will be modified step by step according to the local stress state. Numerical results show the validity of the method.     

基于级联神经网络的蛋白质二级结构预测

为提高蛋白质二级结构预测的精度,提出一种由两层网络构成的级联神经网络模型。第1层网络采用具有差异度的5个子网构成的网络模型,对第2层网络的输入编码进行改进。对PDBSelect25中的36条蛋白质共6 122个残基进行测试,结果表明,该模型能有效预测蛋白质二级结构,其预测精度分别比SNN, DSC, PREDSATOR方法提高5.31%, 1.21%和0.92%,平均预测精度提高到69.61%。     

Modelling water dynamics with DNDC and DAISY in a soil of the North China Plain: A comparative study

The performance of the DNDC and Daisy model to simulate the water dynamics in a floodplain soil of the North China Plain was tested and compared. While the DNDC model uses a simple cascade approach, the Daisy model applies the physically based Richard's equation for simulating water movement in soil. For model testing a three years record of the soil water content from the Dong Bei Wang experimental station near Beijing was used. There, the effect of nitrogen fertilization, irrigation and straw removal on soil water and nitrogen dynamics was investigated in a three factorial field experiment applying a split-split-plot design with 4 replications. The dataset of one treatment was used for model testing and calibration. Two other independent datasets from further treatments were employed for validating the models. For both models, the simulation results were not satisfying using default parameters. After parameter optimisation and the use of site-specific van Genuchten parameters, however, the Daisy model performed well. But, for the DNDC model, parameter optimisation failed to improve the simulation result. Owing to the fact that many biological processes such as plant growth, nitrification or denitrification depend strongly on the soil water content, our findings bring us to the conclusion that the site-specific suitability of the DNDC model for simulating the soil water dynamics should be tested before further simulation of other processes.