自适应尺度的局部强度聚类图像分割模型

针对传统活动轮廓模型无法精确分割强度不均匀图像，并且对尺度参数比较敏感的问题，提出了一种基于区域信息的自适应尺度的活动轮廓模型。根据图像的局部熵构建自适应尺度算子，利用图像的局部强度聚类性质构建能量函数。使用一组平滑基函数的线性组合来表示偏移场，这样可以增加模型的稳定性。通过最小化该能量，所提模型能够同时分割图像和估计偏移场，并且估计的偏移场可以用于强度不均匀校正。实验结果表明，与其它4种模型相比，该模型拥有更高的分割精确度，且分割结果对水平集函数的初始化和噪声具有鲁棒性。     

Simple atmospheric dispersion model to estimate hourly ground-level nitrogen dioxide and ozone concentrations at urban scale

Atmospheric nitrogen dioxide (NO₂) and ozone (O₃) present potential health risk at large urban centres worldwide. Modelling their ground-level concentrations is a fundamental part of urban air quality assessment studies. Simple atmospheric dispersion models are particularly useful in places lacking detailed input data to run complex models and for applications requiring a large number of simulations, also allowing high spatial and temporal resolution even for long-term calculations. The DAUMOD-GRS urban atmospheric dispersion model has been developed aiming to have these features. This work presents its performance evaluation considering hourly concentrations of NO₂ and O₃ measured at twenty sites across the Metropolitan Area of Buenos Aires (MABA), Argentina. Results show an acceptable model performance, with a small tendency to underestimate NO₂ and to overestimate O₃. By grouping the monitoring sites in regions having different emission conditions, it is found that the model reproduces well the observed urban-suburban concentration gradients.     

Parallelisation of the Lagrangian atmospheric dispersion model NAME

The NAME  Atmospheric Dispersion Model is a Lagrangian particle model used by the Met Office to predict the propagation and spread of pollutants in the atmosphere. The model is routinely used in emergency response applications, where it is important to obtain results as quickly as possible. This requirement for a short runtime and the increase in core number of commonly available CPUs, such as the Intel Xeon series, has motivated the parallelisation of NAME  in the OpenMP  shared memory framework. In this work we describe the implementation of this parallelisation strategy in NAME  and discuss the performance of the model for different setups. Due to the independence of the model particles, the parallelisation of the main compute intensive loops is relatively straightforward. The random number generator for modelling sub-grid scale turbulent motion needs to be adapted to ensure that different particles use independent sets of random numbers. We find that on Intel Xeon X5680 CPUs the model shows very good strong scaling up to 12 cores in a realistic emergency response application for predicting the dispersion of volcanic ash in the North Atlantic airspace. We implemented a mechanism for asynchronous reading of meteorological data from disk and demonstrate how this can reduce the runtime if disk access plays a significant role in a model run. To explore the performance on different chip architectures we also ported the part of the code which is used for calculating the gamma dose from a cloud of radioactive particles to a graphics processing unit (GPU) using CUDA-C. We were able to demonstrate a significant speedup of around one order of magnitude relative to the serial CPU version.     

Particle trajectory model of atmospheric dispersion on a parallel processing system

A Lagrangian trajectory model of atmospheric dispersion using the Langevin equation is implemented on a parallel processing computer system, ANUPAM developed at Bhabha Atomic Research Centre, Bombay, India. In the eight-node system with MIMD architecture, a speed-up of 7.22 was achieved using appropriate load balancing between the host node and other nodes. The concentration distribution obtained using the model for two typical cases: (a) high wind shear, low wind speed stable conditions, and (b) low shear, high wind speed unstable conditions, are illustrated with SODAR data as input.     

An overview about the study of downwash effects on dispersion of airborne pollutants

The aim of the present work is to give an overview about the state of the art of the study of the downwash phenomena of airborne pollutants. Accounting for the downwash of pollutant dispersion is of interest because it can contribute to the prevention of dangerous situations by determining in advance what configuration of buildings, stacks, and effluents could cause a high concentration of harmful effluents in a particular area. Recent and less recent studies concerning both building and stack downwash are presented. Some of the presented models are well established and implemented in regulatory air pollutions codes, while other ones are more sophisticated and still under development.     

Sedflux 2.0: An advanced process-response model that generates three-dimensional stratigraphy

Sedflux 2.0 is the newest version of the Sedflux basin-filling model. Sedflux 2.0 provides a framework within which individual process-response models of disparate time and space resolutions communicate with one another to deliver multigrain-sized sediment load across a continental margin. Version 2.0 introduces a series of new process models, and the ability to operate in one of two modes to track the evolution of stratigraphy in either two or three dimensions. Additions to the 2D mode include the addition of models that simulate (1) erosion and deposition of sediment along a riverbed, (2) cross-shore transport due to ocean waves, and (3) turbidity currents and hyperpycnal flows. New processes in the 3D mode include (1) river channel avulsion, (2) two-dimensional diffusion due to ocean storms, and (3) two-dimensional flexure due to sediment loading. The spatial resolution of the architecture is typically 1–25 cm in the vertical and 10–100 m in the horizontal when operating in 2D mode. In 3D mode, the horizontal resolution usually extends to kilometers. In addition to fixed time steps (from days to hundreds of years), Sedflux 2.0 offers event-based time stepping as a way to conduct long-term simulations while still modeling low-frequency but high-energy events.     

OPS: An operational atmospheric transport model for priority substances

The OPS-model (Operational model for Priority Substances) is a flexible atmospheric transport model for the calculation of concentration and deposition of low-reactive pollutants. The averaging period can be chosen from one month up to a period of more than 10 years. The receptor points may be defined on a regular grid in a model domain ranging from the local scale (several 100 m around a source) up to the scale of the European continent (ca. 2000×2000 km) or they may be defined by exact geographical (x,y) coordinates. The latter is for example applicable when the user wishes to compare the model results with measured values from monitoring stations. The emissions can be defined as any combination of point sources and (diffuse) area sources with variable horizontal dimensions. The model uses statistical meteorological data. The minimum set of required meteorological information consists of 6-hourly data for wind speed and direction, global radiation, temperature, and precipitation amount and duration. These data are pre-processed in a separate programme to calculate the necessary statistics.     

Using clouds to scale grid resources: An economic model

Infrastructure as a Service clouds are a flexible and fast way to obtain (virtual) resources as demand varies. Grids, on the other hand, are middleware platforms able to combine resources from different administrative domains for task execution. Clouds can be used by grids as providers of devices such as virtual machines, so they only use the resources they need. But this requires grids to be able to decide when to allocate and release those resources. Here we introduce and analyze by simulations an economic mechanism (a) to set resource prices and (b) resolve when to scale resources depending on the users’ demand. This system has a strong emphasis on fairness, so no user hinders the execution of other users’ tasks by getting too many resources.Our simulator is based on the well-known GridSim software for grid simulation, which we expand to simulate infrastructure clouds. The results show how the proposed system can successfully adapt the amount of allocated resources to the demand, while at the same time ensuring that resources are fairly shared among users.     

A visual discomfort recognition model based on the fusion of multisource information

An experiment was performed to explore the influence of image attributes (white level, black level, color saturation, and sharpness) on visual discomfort, with measurements of the subjective questionnaire, eye movement, and electrocardiogram. The objective and subjective results showed that these image attributes influenced visual discomfort significantly. A visual discomfort recognition model based on Dempster–Shafer evidence theory was proposed according to the experiment results. With multiple features and weighting coefficients, the model could recognize visual discomfort states well.     

Coupling of mesoscale meteorological model with particle trajectory model to study the atmospheric dispersion under sea breeze conditions

A mesoscale meteorological model coupled with a particle trajectory model is used to study the atmospheric dispersion of ⁴¹Ar released through a stack of 100 m height continuously at a rate 1 Bq/s under sea breeze conditions. In a trial study, a mesoscale model successfully simulated the sea breeze phenomena observed at Kalpakkam on 22nd September 1992; the isodose and isoconcentration contours revealed that coupling of the mesoscale meteorological model and the particle trajectory model gives realistic simulation of atmospheric dispersion under such conditions.     

IVVI 2.0: An intelligent vehicle based on computational perception

This paper presents the IVVI 2.0 a smart research platform to foster intelligent systems in vehicles. Computational perception in intelligent transportation systems applications has advantages, such as huge data from vehicle environment, among others, so computer vision systems and laser scanners are the main devices that accomplish this task. Both have been integrated in our intelligent vehicle to develop cutting-edge applications to cope with perception difficulties, data processing algorithms, expert knowledge, and decision-making. The long-term in-vehicle applications, that are presented in this paper, outperform the most significant and fundamental technical limitations, such as, robustness in the face of changing environmental conditions. Our intelligent vehicle operates outdoors with pedestrians and others vehicles, and outperforms illumination variation, i.e.: shadows, low lighting conditions, night vision, among others. So, our applications ensure the suitable robustness and safety in case of a large variety of lighting conditions and complex perception tasks. Some of these complex tasks are overcome by the improvement of other devices, such as, inertial measurement units or differential global positioning systems, or perception architectures that accomplish sensor fusion processes in an efficient and safe manner. Both extra devices and architectures enhance the accuracy of computational perception and outreach the properties of each device separately.     

基于USB2.0的通用PC之间高速通信模块的设计

采用两片USB2.0控制芯片CY7C68013,设计一种通用PC之间点对点的数据传输模块,实现脱离网络环境下通用PC之间的高速数据通信.     

基于局部纹理ASM模型的人脸表情识别

针对主动形状模型(ASM)迭代过程容易陷入局部最优解的不足,提出了一种基于局部纹理模型的改进ASM算法,即EWASM.在局部纹理模型构建中,以每个特征点的中垂线方向搜索其邻域信息以确定最佳匹配位置,对衡量匹配程度的马氏距离加以推广,进而得到改进的扩展加权局部纹理模型,它由中心局部纹理模型、前局部纹理模型和后局部纹理模型共3个子模型加权组成,并对加权参数进行实验优化,使各个特征点之间的联系更加紧密,模型的鲁棒性更好.通过表情识别实验对提出的EWASM算法和传统ASM算法进行对比,选用RBF神经网络分类器进行表情分类,实验结果表明EWASM算法收敛速度更快,识别率也得以提高,并解决了局部最小问题,能更有效地表征表情.     

MinFinder v2.0: An improved version of MinFinder

A new version of the “MinFinder” program is presented that offers an augmented linking procedure for Fortran-77 subprograms, two additional stopping rules and a new start-point rejection mechanism that saves a significant portion of gradient and function evaluations. The method is applied on a set of standard test functions and the results are reported.

New version program summary

Program title: MinFinder v2.0Catalogue identifier: ADWU_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWU_v2_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC Licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 14 150No. of bytes in distributed program, including test data, etc.: 218 144Distribution format: tar.gzProgramming language used: GNU C++, GNU FORTRAN, GNU CComputer: The program is designed to be portable in all systems running the GNU C++ compilerOperating system: Linux, Solaris, FreeBSDRAM: 200 000 bytesClassification: 4.9Catalogue identifier of previous version: ADWU_v1_0Journal reference of previous version: Computer Physics Communications 174 (2006) 166-179Does the new version supersede the previous version?: YesNature of problem: A multitude of problems in science and engineering are often reduced to minimizing a function of many variables. There are instances that a local optimum does not correspond to the desired physical solution and hence the search for a better solution is required. Local optimization techniques can be trapped in any local minimum. Global optimization is then the appropriate tool. For example, solving a non-linear system of equations via optimization, one may encounter many local minima that do not correspond to solutions, i.e. they are far from zero.Solution method: Using a uniform pdf, points are sampled from a rectangular domain. A clustering technique, based on a typical distance and a gradient criterion, is used to decide from which points a local search should be started. Further searching is terminated when all the local minima inside the search domain are thought to be found. This is accomplished via three stopping rules: the “double-box” stopping rule, the “observables” stopping rule and the “expected minimizers” stopping rule.Reasons for the new version: The link procedure for source code in Fortran 77 is enhanced, two additional stopping rules are implemented and a new criterion for accepting-start points, that economizes on function and gradient calls, is introduced.Summary of revisions:

1.

Addition of command line parameters to the utility program make_program.

2.

Augmentation of the link process for Fortran 77 subprograms, by linking the final executable with the g2c library.

3.

Addition of two probabilistic stopping rules.

4.

Introduction of a rejection mechanism to the Checking step of the original method, that reduces the number of gradient evaluations.

Additional comments: A technical report describing the revisions, experiments and test runs is packaged with the source code.Running time: Depending on the objective function.     

大规模化合物子结构检索的并行实现与优化

化合物的子结构检索在计算机辅助药物设计、波普学、化学数据库等领域是不可或缺的工具.然而由于子结构检索是一个NP完备性的问题,获得用户可接受的平均检索时间一直是研究人员十分关注的问题,其方法主要有改进算法和提升硬件条件2个方面.当化学结构数据库的规模达到百万乃至千万级别时,尽管改进算法的方式能够获得一定的检索效率提升,但其提升的空间有限,因而,集群并行方式是大规模化合物子结构检索应用的必然选择.本文以Chem D B Portal的化学子结构检索系统为基础,实现了基于集群并行的化学子结构检索系统,并进行了任务均分、多线程并行等优化.在包含800万个化合物结构的化学结构数据库中,利用5个节点的小型集群,选取10个较为典型的提问结构进行子结构检索测试.测试结果为基于集群的化学子结构检索的平均检索时间由初始单节点时的34.1 min降低为2.75 min,检索效率平均提高12.4倍,表明在大规模乃至超大规模的数据条件下,集群并行化方式能够显著地提高子结构检索系统的执行效率.     

Validation of Kalpana-1 atmospheric motion vectors against upper air observations and numerical model derived winds

Validation of Kalpana-1 atmospheric motion vectors (AMVs) against upper air radiosonde (RS) winds and numerical model-derived winds (National Centre for Medium Range Weather Forecasting's (NCMRWF's) T382L64 first guess) during the monsoon season of 2011 was attempted in this study. This was the first attempt to compare Kalpana-1 AMVs with model-derived winds. An AMV validation against RS winds showed that the mean AMV speed is always higher than that of the mean RS speed, except in high-level cloud motion vectors (CMVs). In the southwest monsoon season of 2011, the maximum speed bias in Kalpana-1 AMV with respect to RS winds was observed in the middle level (～5 m s^?1). The root mean square vector difference (RMSVD) of Kalpana-1 AMV with respect to the collocated RS winds (～5–7 m s^?1) has been found to be in the same range as those of other geostationary satellites, especially over the northern hemisphere and the tropics. The validation of Kalpana-1 AMVs against first guess revealed more erroneous low-level and middle-level AMVs, but the vector difference in the high-level winds was found to be smaller than the same in the low- and middle-level winds. The uncertainty in the empirical genetic algorithm (GA) used to derive the Kalpana-1 AMVs, which does not use model background fields, may be the reason for the high RMSVD of Kalpana-1 AMVs with respect to RS winds and high bias with respect to first guess. The mean observed AMV clearly depicted monsoonal features such as low-level westerly jet (LLWJ) and tropical easterly jet (TEJ). The speed bias density plots of Kalpana-1 high-level CMVs (400–100 hPa) and water vapour channel winds (WVWs) (above ～500 hPa) with respect to first guess showed that the bias was higher for WVWs; however, the standard deviations of high-level CMVs and WVWs are comparable.     

基于GIS的大气污染扩散模拟的设计与实现

对于城市空气环境问题的管理和决策,大气污染扩散模拟系统提供了科学的依据.论述了一个基于GIS,采用Visual Basic.NET、组件MapObjects和组件Surfer8.0相结合的大气污染扩散模拟系统的设计与实现,同时介绍了大气污染扩散的模拟过程、系统的主要功能、MapObjects与Surfer8.0两个组件的部分属性和方法,并给出了实现系统的关键代码.     

基于PC机的模拟信号发生器的设计

本文介绍了一种利用PC机设备来设计模拟信号发生器的方案。该方案通过利用PC机内的充分资源来产生各种所需波形,然后通过USB2.0接口输出。在PC机外采用DAC8580对数字信号进行DA转换,并用CPLD对整个电路进行控制。