Rendering of Surface and Volume Details in Volume Data*

Aiming at the detail rendering in volume data, a new volume illumination model, called Composed Scattering Model (CSM), is presented. In order to enhance different details in volume data, scattering intensity is decomposed into volume scattering intensity and surface scattering intensity with different weight functions. According to the Gauss probability distribution of gray and gradient of data, we propose an accurate method to detect the materials in a voxel, called composed segmentation. In addition, we discuss the principle of constructing these weight functions based on the operators defined in composed segmentation. CSM can generate images containing more details than most popular volume rendering models. This model has been applied to the direct volume rendering of 3D data sets obtained by CT and MRI. The resultant images show not only rich details but also clear boundary surfaces. CSM is demonstrated as an accurate volume rendering model suited for detail enhancement in volume data sets.     

集群系统与公用网互连的仿真模型和模拟算法

在讨论ＭＰＴ１３２７信令的集群移动通信系统与国内Ｎｏ．７信令的ＰＳＴＮ网间互连，帝现两种信令配合中，研究了集群系统的仿真模型和模拟算法，同时模拟出整个集群系统的工作情况，运行结果证实了所提方案的可行性与准确性。     

Generation of adaptive gait patterns for quadruped robot with CPG network including motor dynamic model

This paper describes the generation of adaptive gait patterns using new Central Pattern Generators (CPGs) including motor dynamic models for a quadruped robot under various environments. The CPGs act as the flexible oscillators of the joints and adjust joint angles to required values. The CPGs are interconnected with each other and sets of their coupling parameters are adjusted by a genetic algorithm so that the quadruped robot can realize stable and adequate gait patterns. Generation of gait patterns results in the formation of the CPG networks suitable for the formation of not only a straight walking pattern but also of rotating gait patterns. Experimental results demonstrate that the proposed CPG networks are effective for the automatic adjustment of the adaptive gait patterns for the tested quadruped robot under various environments. Furthermore, the target tracking control based on image processing is achieved by combining the general gait patterns. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 35–43, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20225     

Non‐reflecting artificial boundaries for transient scalar wave propagation in a two‐dimensional infinite homogeneous layer

This paper presents an exact non‐reflecting boundary condition for dealing with transient scalar wave propagation problems in a two‐dimensional infinite homogeneous layer. In order to model the complicated geometry and material properties in the near field, two vertical artificial boundaries are considered in the infinite layer so as to truncate the infinite domain into a finite domain. This treatment requires the appropriate boundary conditions, which are often referred to as the artificial boundary conditions, to be applied on the truncated boundaries. Since the infinite extension direction is different for these two truncated vertical boundaries, namely one extends toward x →∞ and another extends toward x→‐ ∞, the non‐reflecting boundary condition needs to be derived on these two boundaries. Applying the variable separation method to the wave equation results in a reduction in spatial variables by one. The reduced wave equation, which is a time‐dependent partial differential equation with only one spatial variable, can be further changed into a linear first‐order ordinary differential equation by using both the operator splitting method and the modal radiation function concept simultaneously. As a result, the non‐reflecting artificial boundary condition can be obtained by solving the ordinary differential equation whose stability is ensured. Some numerical examples have demonstrated that the non‐reflecting boundary condition is of high accuracy in dealing with scalar wave propagation problems in infinite and semi‐infinite media. Copyright © 2003 John Wiley & Sons, Ltd.     

Bioprocess applications of model-based estimation techniques

The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility.     

European intercomparison on electron spin resonance identification of irradiated foodstuffs

The results of a co-trial organized by the Community Bureau of Reference on the use of Electron Spin Resonance spectroscopy for the identification of irradiated food in 21 laboratories are presented. The trial was qualitative on beef and trout bones, sardine scales, pistachio nut shells, dried grapes, and papaya, and quantitative on poultry bones. There was no difficulty in identifying irradiated meat bones, dried grapes, and papaya. In the case of fish bones there is a need for further kinetic study on different species. Identification of irradiation in pistachio nuts is more complicated and additional research is needed before further trials. All laboratories were able to distinguish between chicken bones irradiated at 1 to 3 kGy or 7 to 10 kGy although there was a partial overlap between the results.     

Comparison of six methylation methods for analysis of the fatty acid composition of albacore lipid

Six methods widely used to produce methyl esters for the gas chromatographic determination of the fatty acid composition of a marine lipid were compared. Four acid-catalyzed methods (1% H₂SO₄: CH₃OH; 5% HCl: CH₃OH; 7% and 14% BF₃: CH₃OH) and two base-catalyzed methods [0.5M NaOCH₃: CH₃OH; (1:4) tetramethylguanidine: CH₃OH] were used.
The use of BF₃: CH₃OH (7% and 14%) gave a lower content of 18:1 n9 than the other methods and produced an artefact (2.7–3.2% of total fatty acid content) eluting between the 20:5 and 24:1 fatty acid methyl esters. No significant differences were obtained between the other four methods.
Accordingly the use of BF₃: CH₃OH for transmethylation of marine lipids is not recommended. Results obtained in the other four methods showed that all are comparable.     

On the design of multiple key hashing files for concurrent orthogonal range retrieval between two disks

This paper concerns the following problem: given a set of multi-attribute records, a fixed number of buckets and a two-disk system, arrange the records into the buckets and then store the buckets between the disks in such a way that, over all possible orthogonal range queries (ORQs), the disk access concurrency is maximized. We shall adopt the multiple key hashing (MKH) method for arranging records into buckets and use the disk modulo (DM) allocation method for storing buckets onto disks. Since the DM allocation method has been shown to be superior to any other allocation methods for allocating an MKH file onto a two-disk system for answering ORQs, the real issue is knowing how to determine an optimal way for organizing the records into buckets based upon the MKH concept.

A performance formula that can be used to evaluate the average response time, over all possible ORQs, of an MKH file in a two-disk system using the DM allocation method is first presented. Based upon this formula, it is shown that our design problem is related to a notoriously difficult problem, namely the Prime Number Problem. Then a performance lower bound and an efficient algorithm for designing optimal MKH files in certain cases are presented. It is pointed out that in some cases the optimal MKH file for ORQs in a two-disk system using the DM allocation method is identical to the optimal MKH file for ORQs in a single-disk system and the optimal average response time in a two-disk system is slightly greater than one half of that in a single-disk system.     

SC文法功能体系

文法体系的研究一直是自然语言处理研究的核心问题之一.但是,由于自然语言本身所固有的复杂性和非规范性,多义问题始终未能得到圆满的解决.本文提出了SC文法(A SubCategory grammar for integrating Se-mantic and Case analysis),它是一种基于传统的上下文无关文法、语义文法,以及超前与反馈分析技术和格框架约束分析等技术的上下文相关处理文法.该文法不仅能继承传统的上下文无关文法的表示简洁、处理方便的特点,而且能实现语法和语义一体化分析和处理上下文相关以及复杂多义问题.