体积图控制的近似刚性的网格变形

现有的形状变形方法大多只关注变形的实时性、保细节性以及交互的灵活性,往往忽视了模型内部的刚性,导致变形过程中不合理的体积变化,进而网格表面的细节难以继续保持.为此,提出一种基于体积图的近似刚性的网格变形方法来约束变形过程中体积的变化.首先构建模型的简单体积图,然后分别在模型表面、内部和体积图边界建立变形单元并根据其不同的类别设计不同的变形权重,最后使用近似刚性的方法实现既保细节又整体近似刚性的变形;另外,文中还对模型加入了材质属性,使得用户可以方便地控制局部的形变.实验结果表明,文中方法操作简单、实用性强.

沥青混合料体积参数通用图的应用研究

为了使沥青混合料体积参数在设计和施工质量控制中得到进一步应用,将体积参数分为直接参数和间接参数.通过对体积参数之间内在关系进行数学推导变形,将沥青混合料设计中通常使用的体积参数与沥青含量之间复杂的非线性关系转变成使用体积参数之间的简单线性关系,适用于不同的沥青混合料设计与评价.在此基础上,进行了体积参数通用图的实际应用研究.理论分析和实际应用结果表明,它可以从体积组成角度去解释压实机理与间接参数之间的关系,从而指导沥青混合料设计与施工控制,值得推广.

P—V图中准静态直线过程的研究

研究了P -V图中理想气体准静态直线过程的变化情况 ,应用两种不同的方法 ,证明了在直线过程中温度最高点与吸放热转换点并不相同 ,并讨论了直线过程的温度和热量转换问题 .

心肌肌钙蛋白T联合DVH图在放射性心肌损伤监测中的应用研究

目的:利用心肌早期损伤特异性标志物心肌肌钙蛋白T(CcTnT)在外周血的检测,分析剂量-体积直方图(DVH图),掌握心脏受照体积和剂量,结合临床与ECG表现,探讨cTnT在放疗中监测心肌损伤的价值。方法:观察38例胸部肿瘤患者放疗前及照射30Gy、40Gy、50Gy时外周血cTnT和ECG的变化,分析DVH图心脏受照体积和剂量。结果:接受过化疗的病人,心脏受照射体积超过2/3,剂量30Gy时出现1例cTnT异常;受量体积45%观察到1例ECG异常。结论:血清cTnT可以做为监测指标,在放疗过程中早期发现心肌损伤以指导治疗。

水利工程技术大体积混凝土施工与优化分析

伴随水利工程的深入发展,促使相关的施工技术越来越成熟。在工程施工中,混凝土材料是至关重要的,在水利工程中也有着普遍的运用。对水利工程施工而言,往往会运用大体积混凝土进行施工建设,因而其施工质量在很大程度上影响着工程的耐久性。基于此,文章针对大体积混凝土进行了一系列分析,首先简述了大体积混凝土概念,接着探讨了质量问题及影响因素,在此基础上,讨论了有关的优化措施,希望可以为有关人员提供借鉴。

多功能光线追踪方法

光线追踪方法已广泛应用于医学图象体积数据的显示。本文将体积图象的许多显示驱动的预处理纳入到光线追踪框架之中，从而形成一个正则化的体积数据显示分析框架。各种处理与分析算子的有机组合可完成各种特定的任务。由于避免了数据的整体预处理，使得体积显示与分析的效率更高、人机交互性能更好。

DVH评价食管癌适形放疗计划对肺的影响

[目的]了解不同食管癌适形放疗计划对肺的影响。[方法]选择7例胸段食管癌病例,用ACQPLAN系统进行CT模拟定位并设计不同适形放疗计划,用剂量体积组方图(DVH)指标进行对比。每一例均设计三野(一前、二后斜)、四野(二前斜、二后斜)和六野(四野加一前一后野),对比以上不同计划中全肺平均接受剂量(Dmean)和受量超过20Gy的肺体积(V20Gy)。[结果]三野和六野计划的肺Dmean较接近,均明显低于四野计划的Dmean(P<0.01);三野计划的V20Gy明显低于四野和六野计划的V20Gy(P<0.01)。三个计划中所有病人的脊髓受照射剂量均在45Gy以下。[结论]综合考虑对脊髓和肺的影响,三野计划为食管癌适形放疗的较优方案。

早期原发胃淋巴瘤三维适形放疗剂量优化研究

目的: 分析早期原发胃淋巴瘤不同三维适形放疗技术(3DCRT)的剂量分布特征,为临床优化应用提供参考。方法:选取9例早期原发胃淋巴瘤患者,在空腹状态下做模拟定位CT,并在CT图像上勾画出胃肿瘤和受累淋巴结、临床靶区(CTV)、计划靶区(PTV),以及邻近危及器官(OARs)。每例设计2种放疗计划:四野3DCRT及上下半束六野的优化3DCRT,用剂量体积关系图分析剂量学结果。结果:四野及优化3DCRT的适形指数分别为0.67±0.06及0.64±0.05;剂量不均匀性指数分别为1.10±0.02及1.11±0.03。左、右肾V15在四野3DCRT及优化3DCRT中分别为(47±30)%、(33±18)%和(24±18)%、(12±12)%。优化3DCRT的肝脏V_(20)较四野3DCRT减少24%。结论:3DCRT能够给予肿瘤靶区均匀的剂量分布,而采用优化六野3DCRT可以更好的保护肾脏、肝脏等危及器官。

3D characterization and analysis of pore structure of packed ore particle beds based on computed tomography images

Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional images of specimens with single particle size of 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 ram. Based on the in-house developed 3D image analysis programs using Matlab, the volume porosity, pore size distribution and degree of connectivity were calculated and analyzed in detail. The results indicate that the volume porosity, the mean diameter of pores and the effective pore size （d50） increase with the increasing of particle size. Lognormal distribution or Gauss distribution is mostly suitable to model the pore size distribution. The degree of connectivity investigated on the basis of cluster-labeling algorithm also increases with increasing the particle size approximately.

Characteristics of rock fragments in different forest stony soil and its relationship with macropore characteristics in mountain area, northern China

Rock fragments have major effect on soil macropores and water movement. However, the characteristics of rock fragments and their relationship with macropore characteristics remain elusive in forest stony soils in northern mountainous area of China. The objectives of this study are to(1) use Industrial Computed Tomography(CT) scanning to quantitatively analyze rock fragment characteristics in intact soil columns in different forest lands and(2) identify the relationship between characteristics of rock fragments and that of the macropores. Intact soil columns that were 100 mm in diameter and 300 mm long were randomly taken from six local forest stony soils in Wuzuolou Forest Station in Miyun, Beijing. Industrial CT was used to scan all soil column samples, and then the scanned images were utilized to obtain the three-dimensional(3 D) images of rock fragments and macropore structures. Next, theparameters of the rock fragments and macropore structure were measured, including the volume, diameter, surface area, and number of rock fragments, as well as the volume, diameter, surface area, length, angle, tortuosity and number of macropores. The results showed that no significant difference was found in soil rock fragments content in the 10-30 cm layer between mixed forest and pure forest, but in the 0-10 cm soil layer, the rock fragments in mixed forest were significantly less than in pure forest. The number density of macropores has significant negative correlation with the number of rock fragments in the 0-10 cm soil layer, whereas this correlation is not significant in 10-20 cm and 20-30 cm soil layers. The volume density of macropore was not correlated with the volume density of rock fragments, and there is no correlation between the density of macropore surface area and the density of rock fragment surface area. Industrial CT scanning combined with image processing technology canprovide a better way to explore 3 D distribution of rock fragments in soil. The content of rock fragments in soil is mainly determined by parent rocks. The surface soil(0-10 cm) of forest contains fewer rock fragments and more macropores, which may be caused by bioturbation, root systems, gravitational settling and faunal undermining.

A Novel Cross-section Interpolation Method for Medical Images

Image interpolation of cross-sections is one of the key steps of medical visualization, and the cubic convolution interpolation is usually employed due to its good tradeoff between computational cost and accuracy, however, sometimes its accuracy can still not meet the requirement. Aimed at the problem, in this paper, the interpolation principle based cubic convolution is firstly analyzed systematically, and then essential relationship among the different cubic convolution interpolation methods is clarified. Lastly, a novel cross-section interpolation method for medical images that is based on the optimal parameter of sharp control is presented. The method takes full advantage of the local characteristic of medical images, and the optimized sharp control parameter is obtained by the iterative computation, and then the cross-section interpolation is performed by the cubic convolution with the optimized parameter in one time.The experimental results show that the method presented in the paper not only can improve the interpolation accuracy effectively, but also is robust.

血液循环检验器

BC检验器是独一无二的非损伤性血液循环检验器，由日本未来之波公司制出，新近已投入市场。

Automatic Liver Segmentation Scheme for MRI Images Based on Cellular Neural Networks

Currently, the processing speed of exist-ing autormtic liver segmentation for Magnetic Res-onance Imaging （MRI） images is rehtively slow. An automatic liver segmentation scheme for MRI irmges based on Cellular Neural Networks （CNN） is presented in this paper. It ensures the validity of this scheme and at the same time completes the im-age segmentation faster to accurately calculate the liver volume by using parallel computing in real time. In order to facilitate the CNN irmge process-hag, firstly, three-dimensional liver MRI images should be transformed into binary images; second- ly, an appropriate template parameter of the Global Connectivity Detection CNN （GCD CNN） shall be selected to probe the connectivity of the liver to extract the entire liver; and then the Hole-Filler CNN （HF CNN） are used to repair the entire extracting liver and improve the accuracy of fiver segmentation; final-ly, the liver volume is obtained. Results show that the scheme can ensure the accuracy of the automatic seg-mentation of the liver, and it can also improve the processing speed at the same time. The liver volume calculated is in line with the clinical diagnosis.

Automatic detection of respiratory rate from electrocardiogram,respiration induced plethysmography and 3D acceleration signals

Respiratory monitoring is increasingly used in clinical and healthcare practices to diagnose chronic cardio-pulmonary functional diseases during various routine activities.Wearable medical devices have realized the possibilities of ubiquitous respiratory monitoring,however,relatively little attention is paid to accuracy and reliability.In previous study,a wearable respiration biofeedback system was designed.In this work,three kinds of signals were mixed to extract respiratory rate,i.e.,respiration inductive plethysmography(RIP),3D-acceleration and ECG.In-situ experiments with twelve subjects indicate that the method significantly improves the accuracy and reliability over a dynamic range of respiration rate.It is possible to derive respiration rate from three signals within mean absolute percentage error 4.37%of a reference gold standard.Similarly studies derive respiratory rate from single-lead ECG within mean absolute percentage error 17%of a reference gold standard.

Shadow Volume in Real-Time Rendering

This paper presents an optimization of shadow volume algorithm, which allow a rendering in real-time. This technique is based on previous works which makes it possible to obtain shadows in real-time, although the calculation of the silhouette requires a pretreatment of the geometry implemented on the CPU （Central Processing Unit）. By using last version of the GPU （Graphic Processing Unit）, the authors propose to implement the calculation of the silhouette on the GPU by using Geometry Shader. The authors present the step which made it possible to lead to a concrete implementation of this algorithm, the modifications which were made, as well as a comparative study of results, followed by a discussion of these results and choices of implementation.

Theoretical research on vacuum separation of Au-Ag alloy

To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.

Improved Correlation for the Volume of Bubble Formed in Air-Water System

In order to address the bubble formation and movement in air-water two-phase flow,single bubble rising in stagnant water is experimentally studied by digital image processing.Bubbles are released individually from the submerged orifices with different diameters(1.81 mm,2.07 mm,2.98 mm,3.92 mm)at different detachment frequency.Images are recorded by a high-speed video camera and processed by digital image processing technique. The factors impacting the formed volume of bubble are discussed.The experimental results showed that a threshold of gas flow rate(400 mm 3 ·s- 1)divides the bubble formation into two regimes:the constant volume regime and the growing volume regime.Especially for the growing volume regime,the surface tension is taken into account.The bubble volume is consisted of two parts:the surface tension impacting part and the gas volume flow rate impacting part.An improved correlation for bubble volume prediction is developed for the two regimes and better coincidence with the experiment data than the previous models is obtained.

A Modified Fixed Point Method for the Perona Malik Equation

In this work we present a new method to solve the Perona Malik equation for the image denoising. The method is based on a modified fixed point algorithm which is fast and stable. We discretize the equation using a finite volume method by integrating the equation using a fuzzy measure on the control volume. To make our algorithm move faster in time, we have used an optimized domain decomposition which generalize the wave relaxation method. Several test of noised images illustrate this approach and show the efficiency of the proposed new method.

Area Variation Based Color Snake Algorithm for Moving Object Tracking

A snake algorithm has been known that it has a strong point in extracting the exact contour of an object. But it is apt to be influenced by scattered edges around the control points. Since the shape of a moving object in 2D image changes a lot due to its rotation and translation in the 3D space, the conventional algorithm that takes into account slowly moving objects cannot provide an appropriate solution. To utilize the advantages of the snake algorithm while minimizing the drawbacks, this paper proposes the area variation based color snake algorithm for moving object tracking. The proposed algorithm includes a new energy term which is used for preserving the shape of an object between two consecutive images. The proposed one can also segment precisely interesting objects on complex image since it is based on color information. Experiment results show that the proposed algorithm is very effective in various environments.

Interpreting effects of TOC_(inert) organic content on source rock potential using S_2 vs. TOC graph in Maamba Coalfield,southern Zambia

The authors present the effects of the total organic carbon( TOCinert) during pyrolysis and how it overall affects the estimates of the hydrocarbon index( HI) using the cross plot S2 vs. TOC graph. A total of 21 drillcore samples consisting of the non-carbonaceous mudstones,carbonaceous mudstones,coaly mudstones and coals with S2> 0. 35 are selected and used. The average TOC for the sampled population is 10. 36 wt%.TOCinertmeasured from the S2 vs. TOC graph is 2. 97 wt% and the average pyrolysable TOCliveis 7. 39 wt%. The HI is 102 mg HC / g TOC and the pyrolysable HI is 175 mg HC / g TOC,indicating that the TOCinertor mi-neral matrix adsorbs some of the hydrocarbons liberated during pyrolysis resulting into the low HI values which affects the correct determination of the source rock potential. Other applications of the S2 vs. TOC cross plot have been used to determine the depositional system tracts. The high stand system tract is also determined through this method.