Objective evaluation of eye strain using measurements of accommodative oscillation

Accommodative oscillations occurring during eye strain induced by two different types of experimental visual search task—visual display terminal (VDT) work and conventional hard-copy (paper) work— were objectively measured using infrared optometry. The low-frequency component (0 to 1-5 Hz) of the accommodative oscillation was found to be significantly increased after the VDT work, but not after the paper work. At other frequencies there were no significant differences between the two work types and no significant effect of the task itself. In a questionnaire survey the subjects using the VDT complained more than the subjects given paper work of ocular symptoms such as eye strain and blurred vision. These results suggest that measurement of changes in accommodative oscillation, particularly the low-frequency component (0 to 15 Hz), may provide an objective parameter of eye strain.     

Visual evoked potentials as indicators of the workload at visual display terminals

No physiological correlates are known for visual fatigue produced by prolonged viewing of visual display terminals (VDTs). The primary aim of the present study was to find a physiological correlate of a performance measure which is related to fatigue. The assumption was that a change in the state of fatigue expresses itself in fluctuations of accommodation. If indeed variations in accommodation are indicative of fatigue, then visual evoked potentials (VEPs) might be used for the objective estimation of fatigue, because pattern EPs are highly sensitive to the quality of the retinal image.

In a realistic visual task, the VEP to pattern onset and the performance to a binary task are recorded simultaneously. Both indicators of fatigue, the amplitude of the VEP and the reaction time, proved to be sensitive to the workload of the task. If accommodation effort was increased, then reaction time increased and VEP amplitude decreased. Thus, VEPs are an indicator of the workload of a visual task. This allows comparison of the fatiguing effects of various office settings on the basis of the pattern EP of a particular subject. However, because VEP amplitude and reaction time do not have the same relation amongst subjects, the pattern EP cannot be used for inter-individual comparison.     

A graphical editor and process visualization system for man-machine interfaces of dynamic systems

The process visualization system of a manmachine interface is presented. It allows human operator(s) to interact with a dynamic technical system, here a thermal power plant. Also, a graphical editor for designing dynamic pictures of the process visualization system is explained. Both new systems have a common architecture and are based on the computer graphics standard PHIGS-2D with extensions for handling non-graphical and graphical information. The hierarchical information structures are manipulated with lists and pointers in a dynamic visual database. The two menu-driven interfaces for designers and for operators are described with their multi-window display layouts. The software of both systems is highly portable to different hardware and to other application domains.     

Physiological effects of intermittently illuminated textual displays

Optical equipment was developed to simulate visual display terminals (VDTs) with reversed presentation (bright background and dark characters). The decay time and mean luminance were kept constant, while the oscillating frequency varied. During one experiment subjects had to read text aloud for 60min. Before and after the reading, near point distance, critical flicker fusion frequency (CFF), visual acuity, stereo depth perception, lateral heterophoria and contrast sensitivity were measured. The 30 subjects had then to report their subjective reactions on a questionnaire. The following frequencies were used: 0, 30, 60, 90, 180 Hz. In addition subjects read a normally printed text with a luminance of 75 or 150 cd/m². The main finding was that of a strong decrease of the CFF after exposure to 30 and 60 Hz. It is suggested that for reversed presentation the refresh rate should be higher than 90 Hz.     

卫星任务规划可视化仿真系统设计与实现

解决卫星任务规划方案正确性、可靠性问题的有效途径是建立可视化仿真分析环境,研究多星多地面站任务规划问题,设计了成像需求约束图模型,利用任务规划调度算法进行优化分析生成最优解决方案,同时研究利用基于MapX的地理信息系统功能,设计实现了卫星任务规划可视化仿真系统,实现了二维视景仿真、方案动作仿真以及可视化决策支持等功能.该系统为卫星任务规划的可视化决策、可视化仿真提供了基础,确保了其正确、可靠性.     

Simulation of n-qubit quantum systems. V. Quantum measurements

The Feynman program has been developed during the last years to support case studies on the dynamics and entanglement of n-qubit quantum registers. Apart from basic transformations and (gate) operations, it currently supports a good number of separability criteria and entanglement measures, quantum channels as well as the parametrizations of various frequently applied objects in quantum information theory, such as (pure and mixed) quantum states, hermitian and unitary matrices or classical probability distributions. With the present update of the Feynman program, we provide a simple access to (the simulation of) quantum measurements. This includes not only the widely-applied projective measurements upon the eigenspaces of some given operator but also single-qubit measurements in various pre- and user-defined bases as well as the support for two-qubit Bell measurements. In addition, we help perform generalized and POVM measurements. Knowing the importance of measurements for many quantum information protocols, e.g., one-way computing, we hope that this update makes the Feynman code an attractive and versatile tool for both, research and education.

New version program summary

Program title: FEYNMANCatalogue identifier: ADWE_v5_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWE_v5_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.: 27 210No. of bytes in distributed program, including test data, etc.: 1 960 471Distribution format: tar.gzProgramming language: Maple 12Computer: Any computer with Maple software installedOperating system: Any system that supports Maple; the program has been tested under Microsoft Windows XP and LinuxClassification: 4.15Catalogue identifier of previous version: ADWE_v4_0Journal reference of previous version: Comput. Phys. Commun. 179 (2008) 647Does the new version supersede the previous version?: YesNature of problem: During the last decade, the field of quantum information science has largely contributed to our understanding of quantum mechanics, and has provided also new and efficient protocols that are used on quantum entanglement. To further analyze the amount and transfer of entanglement in n-qubit quantum protocols, symbolic and numerical simulations need to be handled efficiently.Solution method: Using the computer algebra system Maple, we developed a set of procedures in order to support the definition, manipulation and analysis of n-qubit quantum registers. These procedures also help to deal with (unitary) logic gates and (nonunitary) quantum operations and measurements that act upon the quantum registers. All commands are organized in a hierarchical order and can be used interactively in order to simulate and analyze the evolution of n-qubit quantum systems, both in ideal and noisy quantum circuits.Reasons for new version: Until the present, the FEYNMAN program supported the basic data structures and operations of n-qubit quantum registers [1], a good number of separability and entanglement measures [2], quantum operations (noisy channels) [3] as well as the parametrizations of various frequently applied objects, such as (pure and mixed) quantum states, hermitian and unitary matrices or classical probability distributions [4]. With the current extension, we here add all necessary features to simulate quantum measurements, including the projective measurements in various single-qubit and the two-qubit Bell basis, and POVM measurements. Together with the previously implemented functionality, this greatly enhances the possibilities of analyzing quantum information protocols in which measurements play a central role, e.g., one-way computation.Running time: Most commands require ?10 seconds of processor time on a Pentium 4 processor with ?2 GHz RAM or newer, if they work with quantum registers with five or less qubits. Moreover, about 5-20 MB of working memory is typically needed (in addition to the memory for the Maple environment itself). However, especially when working with symbolic expressions, the requirements on the CPU time and memory critically depend on the size of the quantum registers owing to the exponential growth of the dimension of the associated Hilbert space. For example, complex (symbolic) noise models, i.e. with several Kraus operators, may result in very large expressions that dramatically slow down the evaluation of e.g. distance measures or the final-state entropy, etc. In these cases, Maple's assume facility sometimes helps to reduce the complexity of the symbolic expressions, but more often than not only a numerical evaluation is feasible. Since the various commands can be applied to quite different scenarios, no general scaling rule can be given for the CPU time or the request of memory.References:

[1] T. Radtke, S. Fritzsche, Comput. Phys. Commun. 173 (2005) 91.

[2] T. Radtke, S. Fritzsche, Comput. Phys. Commun. 175 (2006) 145.

[3] T. Radtke, S. Fritzsche, Comput. Phys. Commun. 176 (2007) 617.

[4] T. Radtke, S. Fritzsche, Comput. Phys. Commun. 179 (2008) 647.

     

Simulation of n-qubit quantum systems. II. Separability and entanglement

Studies on the entanglement of n-qubit quantum systems have attracted a lot of interest during recent years. Despite the central role of entanglement in quantum information theory, however, there are still a number of open problems in the theoretical characterization of entangled systems that make symbolic and numerical simulation on n-qubit quantum registers indispensable for present-day research.To facilitate the investigation of the separability and entanglement properties of n-qubit quantum registers, here we present a revised version of the Feynman program in the framework of the computer algebra system Maple. In addition to all previous capabilities of this Maple code for defining and manipulating quantum registers, the program now provides various tools which are necessary for the qualitative and quantitative analysis of entanglement in n-qubit quantum registers. A simple access, in particular, is given to several algebraic separability criteria as well as a number of entanglement measures and related quantities. As in the previous version, symbolic and numeric computations are equally supported.

Program summary

Title of program:FeynmanCatalogue identifier:ADWE_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWE_v2_0Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions:NoneComputers for which the program is designed: All computers with a license of the computer algebra system Maple [Maple is a registered trademark of Waterloo Maple Inc.]Operating systems under which the program has been tested: Linux, MS Windows XPProgramming language used:Maple 10Typical time and memory requirements:Most commands acting on quantum registers with five or less qubits take ?10 seconds of processor time (on a Pentium 4 with ?2 GHz or equivalent) and 5-20 MB of memory. However, storage and time requirements critically depend on the number of qubits, n, in the quantum registers due to the exponential increase of the associated Hilbert space.No. of lines in distributed program, including test data, etc.:3107No. of bytes in distributed program, including test data, etc.:13 859Distribution format:tar.gzReasons for new version:The first program version established the data structures and commands which are needed to build and manipulate quantum registers. Since the (evolution of) entanglement is a central aspect in quantum information processing the current version adds the capability to analyze separability and entanglement of quantum registers by implementing algebraic separability criteria and entanglement measures and related quantities.Does this version supersede the previous version: YesNature of the physical problem: Entanglement has been identified as an essential resource in virtually all aspects of quantum information theory. Therefore, the detection and quantification of entanglement is a necessary prerequisite for many applications, such as quantum computation, communications or quantum cryptography. Up to the present, however, the multipartite entanglement of n-qubit systems has remained largely unexplored owing to the exponential growth of complexity with the number of qubits involved.Method of solution: Using the computer algebra system Maple, a set of procedures has been developed which supports the definition and manipulation of n-qubit quantum registers and quantum logic gates [T. Radtke, S. Fritzsche, Comput. Phys. Comm. 173 (2005) 91]. The provided hierarchy of commands can be used interactively in order to simulate the behavior of n-qubit quantum systems (by applying a number of unitary or non-unitary operations) and to analyze their separability and entanglement properties.Restrictions onto the complexity of the problem: The present version of the program facilitates the setup and the manipulation of quantum registers by means of (predefined) quantum logic gates; it now also provides the tools for performing a symbolic and/or numeric analysis of the entanglement for the quantum states of such registers. Owing to the rapid increase in the computational complexity of multi-qubit systems, however, the time and memory requirements often grow rapidly, especially for symbolic computations. This increase of complexity limits the application of the program to about 6 or 7 qubits on a standard single processor (Pentium 4 with ?2 GHz or equivalent) machine with ?1 GB of memory.Unusual features of the program: The Feynman program has been designed within the framework of Maple for interactive (symbolic or numerical) simulations on n-qubit quantum registers with no other restriction than given by the memory and processor resources of the computer. Whenever possible, both representations of quantum registers in terms of their state vectors and/or density matrices are equally supported by the program. Apart from simulating quantum gates and quantum operations, the program now facilitates also investigations on the separability and the entanglement properties of quantum registers.     

飞机防滑刹车系统的视景仿真设计及实现

针对飞机防滑刹车系统的特点,在Labwindows/CVI环境中利用OpenGL开发工具设计实现了飞机刹车过程的视景仿真.采用OpenCL和3DSMAX相结合的方法逼真、准确地完成了飞机模型设计;通过二次曲面模型、二维贴图、光照以及粒子系统等技术形象地虚拟出了飞机刹车的仿真环境;结合Labwindows/CVI中的图形控件和OpenGL函数实现了多窗口视景;采用RS-485总线技术解决仿真数据的实时通信.通过雨天刹车系统的仿真实例可看出,该系统较好的满足了飞机防滑刹车系统仿真的可视化要求,为飞机防滑刹车系统提供了逼真、实时的视景仿真环境.     

Still‐Frame Simulation for Fire Effects of Images

We propose various simulation strategies to generate single‐frame fire effects for images, as opposed to multi‐frame fire effects for animations. To accelerate 3D simulation and to provide a user with early hints on the final effect, we propose a 2D‐guided 3D simulation approach, which runs a faster 2D simulation first, and then guides 3D simulation using the 2D simulation result. To achieve this, we explore various boundary conditions and develop a constrained projection method. Since only the final frame will be used while intermediate frames are abandoned, earlier intermediate frames can take larger time steps and have large noise applied, quickly generating turbulent flow structures. As the final frame approaches, we increase the flow quality by reducing the time step and not adding any noise. This adaptive time stepping allows us to use more computational resource near or at the final frame. We also develop divergence and buoyancy modification methods to guide flames along arbitrary, even physically implausible, directions. Our simulation methods can effectively and efficiently generate a variety of fire effects useful for image decoration.     

Simulation of advanced microfluidic systems with dissipative particle dynamics

Computational Fluid Dynamics (CFD) is widely and successfully used in standard design processes for microfluidic μTAS devices. But for an increasing number of advanced applications involving the dynamics of small groups of beads, blood cells or biopolymers in microcapillaries or sorting devices, novel simulation techniques are called for. Representing moving rigid or flexible extended dispersed objects poses serious difficulties for traditional CFD schemes. Meshless, particle-based simulation approaches, such as Dissipative Particle Dynamics (DPD) are suited for addressing these complicated flow problems with sufficient numerical efficiency. Objects can conveniently be represented as compound objects embedded seamlessly within an explicit model for the solvent. However, the application of DPD and related methods to realistic problems, in particular the design of microfluidics systems, is not well developed in general. With this work, we demonstrate how the method appears when used in practice, in the process of designing and simulating a specific microfluidic device, a microfluidic chamber representing a prototypical bead-based immunoassay developed in our laboratory (Glatzel et al. 2006a, b; Riegger et al. 2006). Thomas Steiner: born Glatzel.     

基于OpenGVS的油田油气集输过程可视化仿真

借助Visual C＋＋编程环境、利用OpenGVS函数库并使用实时三维建模软件MultiGen Creator,研究了三维对象的模型优化方法、基于OpenGVS的屏幕拾取、纹理映射和碰撞检测等特殊效果的生成技术。建立了脱水站、中转站、污水站、注水站等模型,实现了油田油气集输过程的可视化仿真。通过该系统可以从任意距离和角度观察油田油气集输的各个环节,了解生产设备的内部构造,观察各种动态过程。效果逼真,交互速度快。     

Statistical Analysis and Multimodal Classification on Noisy Eye Tracker and Application Log Data of Children with Autism and ADHD

Emotion recognition behavior and performance may vary between people with major neurodevelopmental disorders such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD) and control groups. It is crucial to identify these differences for early diagnosis and individual treatment purposes. This study represents a methodology by using statistical data analysis and machine learning to provide help to psychiatrists and therapists on the diagnosis and individualized treatment of participants with ASD and ADHD. In this paper we propose an emotion recognition experiment environment and collect eye tracker fixation data together with the application log data (APL). In order to detect the diagnosis of the participant we used classification algorithms with the Tomek links noise removing method. The highest classification accuracy results were reported as 86.36% for ASD vs. Control, 81.82% for ADHD vs. Control and 70.83% for ASD vs. ADHD. This study provides evidence that fixation and APL data have distinguishing features for the diagnosis of ASD and ADHD.     

Simulation aided design of organizational structures in manufacturing systems using structuring strategies

This paper presents a simulation aided approach for designing organizational structures in manufacturing systems. The approach is based on a detailed modeling and characterization of the forecasted order program, especially of elementary processes, activity networks and manufacturing orders. Under the use of the organization modeling system FORM, that has been developed at the ifab-Institute of Human and Industrial Engineering of the University of Karlsruhe, structuring strategies—e.g., a process-oriented strategy—can be applied in order to design organizational structures in manufacturing systems in a flexible and efficient way. Following that, a dynamical analysis of the created manufacturing structures can be carried out with the simulation tool FEMOS, that has also been developed at the ifab-Institute. The evaluation module of FEMOS enables to measure the designed solutions with the help of logistical—e.g., lead time degree—and organizational—e.g., degree of autonomy—key data. This evaluation is the basis for the identification of effective manufacturing systems and also of improvement potentialities. Finally, a case study is presented in this paper designing and analyzing different organizational structures of a manufacturing system where gear boxes and robot grip arms were manufactured.     

Interactive Large‐Scale Procedural Forest Construction and Visualization Based on Particle Flow Simulation

Interactive visualization of large forest scenes is challenging due to the large amount of geometric detail that needs to be generated and stored, particularly in scenarios with a moving observer such as forest walkthroughs or overflights. Here, we present a new method for large‐scale procedural forest generation and visualization at interactive rates. We propose a hybrid approach by combining geometry‐based and volumetric modelling techniques with gradually transitioning level of detail (LOD). Nearer trees are constructed using an extended particle flow algorithm, in which particle trails outline the tree ramification in an inverse direction, i.e. from the leaves towards the roots. Reduced geometric representation of a tree is obtained by subsampling the trails. For distant trees, a new volumetric rendering technique in pixel‐space is introduced, which avoids geometry formation altogether and enables visualization of vast forest areas with millions of unique trees. We demonstrate that a GPU‐based implementation of the proposed method provides interactive frame rates in forest overflight scenarios, where new trees are constructed and their LOD adjusted on the fly.     

城市公共自行车租赁系统站点配车数仿真优化

城市公共自行车系统旨在满足当地居民“最后一公里”的出行需求,因其低成本且环保的特点受到越来越多城市的欢迎,但整个系统涉及人流量、出行方式及交通状况等多层因素,难以构建数学模型进行定量描述。依据某市公共自行车系统的运营情况,采用系统建模的方式,构建基于Plant Simulation的公共自行车系统仿真模型,以站点服务度和设施利用率为评价指标,对各个租赁站点的配车数进行了分析。利用敏感性分析和迭代相结合的方法,在平衡服务质量和设施利用率的情况下,对各公共自行车租赁站点的配车数进行了优化,仿真结果表明优化后的配车数有利于改善系统的服务质量。     

Real-Time Simulation of Thin Shells

This paper proposes a real-time simulation technique for thin shells undergoing large deformation. Shells are thin objects such as leaves and papers that can be abstracted as 2D structures. Development of a satisfactory physical model that runs in real-time but produces visually convincing animation of thin shells has been remaining a challenge in computer graphics. Rather than resorting to shell theory which involves the most complex formulations in continuum mechanics, we adopt the energy functions from the discrete shells proposed by Grinspun et al. [ [GHDS03] ]. For real-time integration of the governing equation, we develop a modal warping technique for shells. This new simulation framework results from making extensions to the original modal warping technique [ [CK05] ] which was developed for the simulation of 3D solids. We report experimental results, which show that the proposed method runs in real-time even for large meshes, and that it can simulate large bending and/or twisting deformations with acceptable realism.     

非均匀区域油藏模拟负载平衡的分区并行算法*

基于分布式并行计算机系统,对一类非均匀区域的油藏数值模拟问题,采用了区域分解方法并行求解,给出了并行求解的负载平衡模型及区域负载平衡的一种有效分区算法,从而将这类油藏数值模拟问题均衡映射到并行环境中,高效地并行求解.在黑油油藏数值模拟并行软件的研究中,实验结果表明,该算法有利于提高加速比.     

基于多层油藏问题负载均衡的并行任务划分

该文基于分布式并行计算机系统,对一类多层二维二相流油藏数值模拟问题给出了3种任务划分策略—“卷帘”方式、区域分解方式和“卷帘”与区域分解结合的方式,对它们进行了比较,提出了减少求解时间、利于负载均衡和提高并行性能的任务划分方法,并实际应用于有多达72万个网格节点的大规模油藏模拟问题.实算结果表明,该策略划分产生的并行求解任务均衡,有利于加速比的提高.该方法也适用于区域或数据并行的任务划分问题.     

An Evaluation of the Reliability of Complex Systems Using Shadowed Sets and Fuzzy Lifetime Data

In this paper, we consider the problem of the evaluation of system reliability using statistical data obtained from reliability tests of its elements, in which the lifetimes of elements are described using an exponential distribution. We assume that this lifetime data may be reported imprecisely and that this lack of precision may be described using fuzzy sets. As the direct application of the fuzzy sets methodology leads in this case to very complicated and time consuming calculations, we propose simple approximations of fuzzy numbers using shadowed sets introduced by Pedrycz (1998). The proposed methodology may be simply extended to the case of general lifetime probability distributions.