A Rough Set Based Model in Water Quality Analysis

Due to pollution caused by the expansion of human activities and economic development, water quality has gradually deteriorated in many areas of the world. Therefore, analysis of water quality becomes one of the most essential issues of modern civilization. Integrated interdisciplinary modeling techniques, providing reliable, efficient, and accurate representation of the complex phenomenon of water quality, have gained attention in recent years. With the ability to deal with both numeric and nominal information, and express knowledge in a rule-based form, the Rough Set Theory (RST) has been successfully employed in many fields. However, the application of RST has not been widely investigated in water quality analysis. The reducts generated by RST models become very time-consuming as the size of the problem increases. Using multinomial logistics regression (MLR) techniques to provide reducts of RST models, this investigation develops a hybrid Multinomial Logistic Regression and Rough Set Theory (MLRRST) model to analyze relations between degrees of water pollution and environmental factors in Taiwan. Empirical results indicate that the MLRRST model could analyze water qualities efficiently and accurately, and yield decision rules for the staff of water quality management. Thus, the proposed model is a promising and helpful scheme in analyzing water quality.     

Microstructural refinement and tensile properties enhancement of Mg-3Al alloy using charcoal additions

Significant grain refinement in Mg-3Al alloy is achieved with the addition of charcoal due to the formation of Al₄C₃ particles, which act as effective nuclei for magnesium grains. Addition of 0.5 wt% charcoal has lead to reduced grain size of Mg-3Al alloy from 500 to 80 μm and no substantial grain refinement is obtained on further addition of charcoal. The results further reveal that the prolonged holding of the melt after the addition of charcoal has not affected the grain refining efficiency of Al₄C₃. Steady increase in tensile properties observed with increasing amount of charcoal addition has been attributed to the grain refinement and the presence of fine Al₄C₃ particles. The strengthening mechanisms due to charcoal addition are discussed in terms of Hall-Petch relation and dispersion strengthening. The predicted values are in good agreement with experimental results.     

作为片断的系统,作为系统的片断——曹敏硕和MASS STUDIES事务所的建筑语汇

<正>我们如何构建高密度建筑的理论?社区的概念能否与这种大都市建筑契合?亦即,当建筑周边土地价格和空间成本十分高昂,以至于在某种程度上可以说每一寸土地都在为资本主义服务的时候,应该如何实现建筑和社区的概念?这些问题当然不甚鲜见。在战后美国、欧洲和日本经济扩张的背景下,路易·康、十人小组、阿     

Effect of the Strength of the Material of a Plate Accelerated by Low-Rate High Explosives

Plate acceleration by a gliding detonation wave is studied experimentally for detonation rates of 950–2000 m/sec. It is found that regular elastic waves occur at the surface of the projectile plate made of a rather strong material, which disappear upon attainment of the upper limit of the detonation rate.     

一种改进的基子波束形成和复倒谱滤波的语音去混响方法

本文在波束形成和复倒谱滤波的室内语音去混响方法基础上，引入加指数窗方法使语音信号最小相位化，形成了一种改进方法，该方法使计算量约减少了一半。并运用四种客观音质评价指标和两种主观音质评价指标，分别对各种去混响方法进行仿真实验评测，结果表明改进方法的去混响性能有明显的改善。     

Rsim: simulating shared-memory multiprocessors with ILP processors

The early 1990s saw several announcements of commercial shared-memory systems using processors that aggressively exploited instruction-level parallelism (ILP), including the MIPS R10000, Hewlett-Packard PA8000, and Intel Pentium Pro. These processors could potentially reduce memory read stalls by overlapping read latency with other operations, possibly changing the nature of performance bottlenecks in the system. The authors' experience with Rsim demonstrates that modeling ILP features is important even in shared-memory multiprocessor systems. In particular, current simple processor-based approximations cannot model significant performance effects for applications exhibiting parallel read misses. Further, recent shared-memory designs such as aggressive implementations of sequential consistency use the aggressive ILP-enhancing features of modern processors that simple processor-based simulators do not model. As microprocessor systems become more complex, the availability of shared infrastructure source code is likely to become increasingly crucial. The authors plan to release a new Rsim version shortly that will include instruction caches, TLBs, multimedia extensions, simultaneous multithreading, Rabbit fast simulation mode, and ports to Linux platforms     

STRANDS: Interactive Simulation of Thin Solids using Cosserat Models

Strands are thin elastic solids that are visually well approximated as smooth curves, and yet possess essential physical behaviors characteristic of solid objects such as twisting. Common examples in computer graphics include: sutures, catheters, and tendons in surgical simulation; hairs, ropes, and vegetation in animation. Physical models based on spring meshes or 3D finite elements for such thin solids are either inaccurate or inefficient for interactive simulation. In this paper we show that models based on the Cosserat theory of elastic rods are very well suited for interactive simulation of these objects. The physical model reduces to a system of spatial ordinary differential equations that can be solved efficiently for typical boundary conditions. The model handles the important geometric non‐linearity due to large changes in shape. We introduce Cosserat‐type physical models, describe efficient numerical methods for interactive simulation of these models, and implementation results.     

Application of Sequential Learning Neural Networks to Civil Engineering Modeling Problems

A sequential orthogonal approach to the building and training of a single hidden layer neural network is presented in this paper. The Sequential Learning Neural Network (SLNN) model proposed by Zhang and Morris [1]is used in this paper to tackle the common problem encountered by the conventional Feed Forward Neural Network (FFNN) in determining the network structure in the number of hidden layers and the number of hidden neurons in each layer. The procedure starts with a single hidden neuron and sequentially increases in the number of hidden neurons until the model error is sufficiently small. The classical Gram–Schmidt orthogonalization method is used at each step to form a set of orthogonal bases for the space spanned by output vectors of the hidden neurons. In this approach it is possible to determine the necessary number of hidden neurons required. However, for the problems investigated in this paper, one hidden neuron itself is sufficient to achieve the desired accuracy. The neural network architecture has been trained and tested on two practical civil engineering problems – soil classification, and the prediction o strength and workability of high performance concrete.     

Cerebral blood flow velocity and vasomotor reactivity before and after shunting surgery in patients with normal pressure hydrocephalus

The purpose of this study was to evaluate pre- and post-shunting haemodynamic changes and their correlation with the clinical results in normal pressure hydrocephalus (NPH). Accordingly, eleven demented patients with clinical signs suggestive of NPH received examinations of cerebral blood flow velocity (BFV) and vasomotor reactivity (VMR) by transcranial Doppler sonography with carbogen testing before and after shunt treatment. Computerized tomography (CT), clinical assessment and neuropsychological grading were performed prior to and at 3 months following surgery. A control group consisting of 10 patients was included to establish baseline data. The pre-operative CBF studies in the anterior cerebral artery (ACA) and the middle cerebral artery (MCA) revealed the NPH patients did not have significant decreases of BFVs, but had significant decreases of carbogen VMR (P < 0.05). After shunting, there were no significant changes of the BFVs as compared with the pre-shunting data. The post-shunting VMR of the ACA was significantly higher than the pre-shunting one (p < 0.05), but there was no variation in that of the MCA. Both the values of post-shunting VMR in ACA and the post-shunting increase in VMR in MCA of the 7 shunt-responsive patients who improved mentally and in other symptoms were significantly higher than those of patients without improvement (p < 0.05). In addition, the five patients with gait improvement showed significantly higher values of post-shunting VMR of ACA and the post-shunting increase of VMR for both ACA and MCA when compared with those patients without gait improvement (p < 0.05, respectively). Our study supports the view that patients with NPH had various degrees of impaired VMR in both the ACA and the MCA, but showed insignificant reduction in BFVs, indicating a compensatory mechanism of CBF over time to accommodate the subnormal state of cerebral perfusion pressure. Shunt placement would improve the VMR in responsive patients. Postoperatively, an increase of VMR tends to accompany improvement of the functional state: that in the MCA alone is associated with symptomatic improvement in mental function and that increase in VMR in both the ACA and the MCA with improvement in gait, respectively.