On finding optimal and near-optimal lineal spanning trees

The search for good lineal, or depth-first, spanning trees is an important aspect in the implementation of a wide assortment of graph algorithms. We consider the complexity of findingoptimal lineal spanning trees under various notions of optimality. In particular, we show that several natural problems, such as constructing a shortest or a tallest lineal tree, are NP-hard. We also address the issue of polynomial-time, near-optimization strategies for these difficult problems, showing that efficient absolute approximation algorithms cannot exist unlessP = NP.This author's research was supported in part by the Sandia University Research Program and by the National Science Foundation under Grant M IP-8603879.This author's research was supported in part by the National Science Foundation under Grants ECS-8403859 and MIP-8603879.     

Applications of the 4×4 determinant method and the POLYGON ENGINE

In the first half of the paper, various types of processing pertaining to a polygon, using the 4×4 determinant theories are explained along with a new containment test algorithm of a point in a polygon. In the latter half of the paper, a general-purpose geometric processor, the POLYGON ENGINE, is presented which can deal with various types of interference problems, such as Boolean operations in solid modelling, hidden line and surface eliminations, ray tracing and so on. It is, a successor of the TRIANGLE PROCESSOR and is also based upon the 4×4 determinant theories [4–6]. While the TRIANGLE PROCESSOR processes a triangulated polygon on a triangle-by-triangle basis, the POLYGON ENGINE can treat a polygon without triangulation. The latter is expected to be more functional, more efficient and easier to use.     

Parallel branch-and-bound search in Parlog

The concurrent logic languages, of which Parlog is one, have been promoted as a new generation of software languages specifically designed for parallel programming. This paper investigates their application to a search problem commonly used as an illustration of artificial intelligence techniques, the 8-puzzle. It notes that programs written in the concurrent logic languages which do not pay attention to the parallelism can fall into two possible traps: either there is little real parallelism in them due to data dependencies, or there is too much parallelism and any practical architecture will be overwhelmed. A solution which controls the parallelism using user-defined priorities is proposed. This solution has the advantage of being architecture-independent.     

Network model approach for calculating oscillating frequency of thermoacoustic prime mover

The network model is given and used to calculate the oscillating frequency of thermoacoustic prime mover. Theoretically calculated frequency by the model is plural, whose real part denotes actual frequency of the system, and imaginary part means attenuation coefficient of acoustic pressure. Numerical calculation is made under different conditions including different acoustic cavities, spacing between each parallel plate, gas pressures and system lengths. Theoretically calculated frequency and experimentally measured frequency are in quite good agreement.     

Age effects in coding tasks: Componential analysis and test of the sensory deficit hypothesis.

Multiple forms of a symbol-digit substitution task were used to provide a componential analysis of age differences in coding task performance. The results demonstrated age differences in feature encoding, memory, and visual search. A 2nd experiment was conducted with young adults to investigate a sensory deficit as a locus of age differences. The spatial contrast sensitivity deficit of older adults was simulated on forms by applying a digital filter. Persons in the age-simulated contrast condition performed worse than those in the normal contrast condition. The stimulus degradation effect was linked to visual search speed. The study illustrates the utility of componential analysis and offers direct support for the hypothesis that sensory deficits affect performance on tasks used to assess intelligence (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

LC4L-20增压中冷柴油机的研制

介绍了LC4L-20增压中冷柴油机的性能与结构特点，着重分析了增压中冷技术，及各主要运动件的可靠性设计。     

铁谱技术在判断发动机磨损状态中的应用研究

发动机中各摩擦副的工作环境恶劣，磨拟状态复杂，很难精确描述。而发动机所处的磨损状态是判断其是否正常工作的重要标准，因此建立发动机磨损状态监测具有重大的经济和社会效益。笔者利用铁谱技术作为一种监测手段，通过磨粒分析来判断发动机的磨损状态。     

涡轮增压柴油机模拟计算等压法的探讨

针对有些模拟计算可以忽略排气压力波的影响，提出了等压法计算的设想，这是一种每一工作循环缸外热力过程只计算一次的简化方法。分析结果表明，这种计算可以满足零维模型必须满足的所有制约方程，能真实地模拟涡轮增压柴油机的实际工作过程，适用于各种增压系统，但仍有待于进一步的研究与改进。根据等压法，建立了一种适用于定压涡轮系统的计算模型--“定压涡轮”模型，用于MPC增压系统的计算，计算结果与试验结果基本吻合，与容积法计算结果趋于一致，从而验证了模型的正确性，同时也表明这种缸外计算法是有效的。     

基于虚拟测试技术的柴油机燃烧分析系统

运用虚拟仪器技术,开发了一种柴油机燃烧分析仪。该分析仪由高速数据采集卡及自行开发的控制软件组成。本文介绍了此分析系统的软件开发方法,并探讨了上止点的修正、示功图的光顺处理等问题。     

Plasticity of feature-based selection in triple-conjunction search.

Two experiments examined the disruption of feature-based selection in triple-conjunction search at multiple target transfers. In Experiment 1, after 10 training sessions, a new target possessing previous distractor features was introduced. This produced disruption in RT and fixation number, but no disruption in feature-based selection. Specifically, there was a tendency to fixate objects sharing the target's contrast polarity and shape and this did not change even upon transfer to the new target. In Experiment 2, 30 training sessions were provided with three target transfers. At the first transfer, the results replicated Experiment 1. Subsequent transfers did not produce disruption on any measure. These findings are discussed in terms of strength theory, Guided Search, rule-based approaches to perceptual learning, and the area activation model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)