Highly repetitive, extreme-ultraviolet radiation source based on a gas-discharge plasma.

An extreme-ultraviolet (EUV) radiation source near the 13-nm wavelength generated in a small (1.1 J) pinch plasma is presented. The ignition of the plasma occurs in a pseudosparklike electrode geometry, which allows for omitting a switch between the storage capacity and the electrode system and for low inductive coupling of the electrically stored energy to the plasma. Thus energies of only a few joules are sufficient to create current pulses in the range of several kiloamperes, which lead to a compression and a heating of the plasmas to electron densities of more than 10(17) cm(-3) and temperatures of several tens of electron volts, which is necessary for emission in the EUV range. As an example, the emission spectrum of an oxygen plasma in the 11-18-nm range is presented. Transitions of beryllium- and lithium-like oxygen ions can be identified. Current waveform and time-resolved measurements of the EUV emission are discussed. In initial experiments a repetitive operation at nearly 0.2 kHz could be demonstrated. Additionally, the broadband emission of a xenon plasma generated in a 2.2-J discharge is presented.     

New approach for air traffic management based on control theory

Air traffic management aims to provide solutions to congestion problems in air traffic networks (ATNs) which in turn are mainly generated by the variation in the capacity of air sectors or airports due to adverse weather conditions. Most of the existing approaches to dealing with these problems are based on mathematical programming techniques and inherit its computational difficulty. In this paper, we introduce a control scientist point of view to this topic by proposing an approach to solve the ground-holding problem based on discrete event systems control theory. An ATN can effectively be considered as a timed discrete event system and can be efficiently modelled based on a Time Petri net tool. The main advantage is an explicit representation of the position of each aircraft in the ATN at each time instant. The state space is modelled by a Discrete Time Reachability Graph and the capacity constraints on the air sectors are modelled by time floating general mutual exclusion constraints. Feasible flight plans can be constructed based on control synthesis techniques, while an algorithm to compute the optimal flight plan is proposed assuming a realistic cost function.     

New metric for stereo image quality assessment based on HVS

Stereo image is regarded as an important trend of image technology, and there is an increasing need to develop efficient measures for stereo image quality evaluation. By analyzing the main properties of human visual system that is related to stereo image, a new metric based on human visual systems (HVSs) for stereo image quality assessment is proposed in this article. This method assesses stereo images from the perspective of image quality and stereo sense. The experimental results are presented to show that the proposed metric provides results consistent with the subjective assessment and thus can be employed to reflect image quality and stereo sense. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 301–307, 2010     

Enhancement in quality and productivity: a riskless approach based on optimum selection of tolerance and improvement strategies

The need of higher quality products from the customers and the tendency of industries to quality improvement for maintaining their competitive position over the long run are the main motives of using improvement methodologies. However, any use of improvement methodology besides its additional costs will also change the total variability of the process. Changes in total variability will affect the optimal value of tolerance as well as the quality of the product. Therefore, one of the main concerns of the producers is to find an effective way to manufacture their goods in a manner that reduces the production costs and gains customers’ satisfaction. To meet these goals, this study introduces an algorithm to propose a riskless approach of improvement that results in the maximum amount of net savings. It is shown that using appropriate improvement strategies simultaneous with a proper selection of tolerance have an important impact to enhance productivity and quality.     

MYRRHA, a Pb-Bi experimental ADS: specific approach to radiation protection aspects

Since 1998, SCK*CEN, in partnership with IBA s.a. and many European research laboratories, is designing a multipurpose accelerator driven system (ADS) for Research and Development (R&D) applications-MYRRHA-and is conducting an associated R&D support programme. MYRRHA is an ADS under development at Mol in Belgium and is aiming to serve as a basis for the European experimental ADS to provide protons and neutrons for various R&D applications. It consists of a proton accelerator delivering a 350 MeV x 5 mA proton beam to a liquid Pb-Bi spallation target that in turn couples to a Pb-Bi cooled, subcritical fast core. In the first stage, the project focuses mainly on demonstration of the ADS concept, safety research on sub-critical systems and nuclear waste transmutation studies. In a later stage, the device will also be dedicated to research on structural materials, nuclear fuel, liquid metal technology and associated aspects, and on sub-critical reactor physics. Subsequently, it will be used for research on applications such as radioisotope production. A first preliminary conceptual design file of MYRRHA was completed by the end of 2001 and has been reviewed by an International Technical Guidance Committee, which concluded that there are no show stoppers in the project and even though some topics such as the safety studies and the fuel qualification need to be addressed more deeply before concluding it. In this paper, we are reporting on the state-of-the art of the MYRRHA project at the beginning of 2004 and in particular on the radiation shielding assessment and the radiation protection particular aspects through a remote handling operation approach in order to minimise the personnel exposure to radiation.     

Systematical decision-making approach for quality function deployment based on uncertain linguistic term sets

A systematical decision-making approach is constructed for quality function deployment (QFD) in uncertain linguistic situations. The mathematical expression and operation of linguistic terms play important roles in the proposed approach in terms of customer requirements (CRs) and design requirements (DRs) in QFD. First, hesitant fuzzy linguistic term sets are designed to conveniently express uncertain linguistic terms and compute with words after the data derived from customers are pretreated and integrated in the decision-making process. Second, the tolerance deviation is defined to restrict innovatively the deviation range of fuzzy linguistic terms in the assessment stage of relative importance for CRs. Third, information entropy is originally designed to determine the final importance of DRs. Moreover, an empirical study on the research project called vortex recoil hydraulic retarder is conducted to demonstrate the performance of the systematical decision-making approach. The proposed approach can be applied to a wide variety of new product development problems in uncertainty settings.     

结构噪声主动控制在时域声辐射模态下的仿真研究

以简支矩形板为例，提出了利用时域声辐射模态进行声辐射研究。研究表明时域声辐射模态既与时间无关，且互相独立，使得计算和控制声功率得以简化。针对瞬时声功率主要由第一阶辐射模态的声功率所决定的特点，在时域里进行结构噪声的主动控制研究，通过抵消第一阶辐射模态的声功率使得总的声功率得以有效降低。在此基础上，建立了时域声辐射模态的状态空间方程，对该方程的性能进行了分析，并利用最优控制算法的自适应反馈控制系统进行仿真计算。最后讨论了不同情况下的计算精度，并对影响仿真结果的因素进行了分析。     

Performance measurement for a manufacturing system based on quality,cost and time

Product quality, manufacturing cost and manufacturing time are three of the major concerns in a manufacturing system. This study proposes a product capability index to evaluate the quality of a multi-process product and addresses the relationship between process yield and the product capability index. In addition, this paper develops a time–cost index to assess manufacturing cost and manufacturing time. The quality index and time–cost index are simultaneously used to monitor product quality and manufacturing time on a quality and time–cost analysis chart. The quality and time–cost analysis chart, providing accurate information on the quality status and time–cost status for each process, helps to initiate, effectively and efficiently, quality improvement plans to elevate product quality and manufacturing time and manufacturing cost control for a manufacturing system.     

A hybrid radiation detector based on a plasma display panel

Recently, large-area image detectors have been investigated for X-ray imaging in medical diagnostic and other applications. In this paper, a new type of radiation detector is described, based on the integration of a photoconductor into a plasma display panel (PDP). This device, called a hybrid PDP detector, should be quite inexpensive, because it can directly leverage off the fabrication and materials technologies widely used in plasma display panels. Also, these new radiation detectors should operate under the most challenging environmental conditions, because they are inherently rugged and radiation-resistant and insensitive to magnetic fields. In this paper, we describe a hybrid digital radiation detector device, based on plasma display. The PDP panel is 7 in. in size with a 1000-μm pixel pitch, and filled with 700 Torr of Xe gas; the hybrid PDP panel is of the same structure, except for the photoconductor deposit. The glass absorption, dark current, X-ray sensitivity, and linearity as a function of electric field were measured to investigate its electrical properties. From the results, stabilized dark current density and significant X-ray sensitivity were obtained with both panels; however, the hybrid PDP detector showed better characteristics than the PDP detector. It also had good signal response and linearity. The hybrid digital radiation detector device based on a plasma display seems to be a promising technology for use in radiology and dynamic moving imaging.     

Robot selection using an integrated approach based on quality function deployment and fuzzy regression

The decision-makers have been experiencing difficulties in determining the most suitable robot alternative due to the increase in number of robots and the diversity in their application areas. A robust decision framework for robot selection should consider multiple and conflicting criteria and the dependencies among them. This paper introduces a decision model for robot selection based on quality function deployment (QFD) and fuzzy linear regression. The proposed approach benefits from the fact that QFD focuses on delivering value by taking into account the customer requirements and then by deploying this information throughout the development process, and applies this perspective to robot selection. Fuzzy linear regression is considered as an alternative decision aid for robot selection problems where imprecise relationships among system parameters exist. An example robot selection problem is presented to illustrate the proposed decision-making approach.     

A rough set based data mining approach for house of quality analysis

As the first phase of quality function deployment (QFD) and the only interface between the customers and product development team, house of quality (HOQ) plays the most important role in developing quality products that are able to satisfy customer needs. No matter in what shape or form HOQ can be built, the key to this process is to find out the hidden relationship between customers’ requirements and product design specifications. This paper presents a general rough set based data mining approach for HOQ analysis. It utilises the historical information of customer needs and the design specifications of the product that was purchased, employs the basic rough set notions to reveal the interrelationships between customer needs and design specifications automatically. Due to the data reduction nature of the approach, a minimal set of customer needs that are crucial for the decision on the correlated design specifications is derived. The end result of the approach is in the form of a minimal rule set, which not only fulfils the goal of HOQ, but can be used as supporting data for marketing purposes. A case study on the product of electrically powered bicycles is included to illustrate the approach and its efficiency.     

Gafchromic film as a fast visual indicator of radiation exposure of first responders

Three types of Gafchromic films have been studied to investigate their potential for use as a visually readable dosemeter for persons acting as first responders in connection with radiological or nuclear emergencies. The two most sensitive film types show a pronounced variation in sensitivity by photon energy and are therefore not suitable for use in cases of unknown exposures. The third film type tested (RTQA2), which is intended for quality control in radiation therapy has a sensitivity that is independent of the radiation quality, and is therefore considered as the most optimal for visual reading in situ. Tests carried out on a group of 10 human observers showed that absorbed doses down to 40 mGy can be detected by the eye. Read by a portable densitometer, qualitative absorbed dose estimates down to 9 mGy can be achieved. The colour change is obtained instantaneously, giving first responders immediate information about the presence of beta-, gamma- and X-ray radiation.     

Intraframe image decoding based on a nonlinear variational approach

Despite advances in the domain of source coding, little recent work has been devoted to the problem of joint coding and decoding. In particular, to our knowledge, the design of decoders has been little investigated. In this article, we focus on decoding for intraframe images of video data. In our approach, we propose a new method for decoding by nonlinear filtering. Here, we break with the usual approach of perfect reconstruction filters at the decoder, and instead pose the reconstruction model as a minimization problem. The solution can be viewed as an inverse problem with the optimization of the transform/quantization/decoding structure formulated using a variational approach. We introduce sufficient conditions on the design of the decoder involving a priori assumptions on the solution and knowledge of the coder (transformation and quantization). We develop an optimization method for the reconstruction filters at the decoder to account for effects due to quantization noise. Experiments using this nonlinear inverse dynamic filtering demonstrate peak signal-to-noise ratio gains over standard linear inverse filtering as well as appreciable visual improvements. © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 369–380, 1998     

Numerical modelling of concrete cracking based on a stochastic approach

Concrete is a highly heterogeneous material, because of its composite structure, but also because of the physical phenomena that take place during hardening (initial stresses, drying shrinkage, heat exchanges). This heterogeneity can explain some aspects of the complex mechanical behaviour of concrete, particularly the transition from uniform to localized cracking and the important size effect. A numerical procedure taking the statistical aspects of this heterogeneity into account has been developed and implemented. It permits us to reproduce and explain the principal experimental results for the behaviour of concrete under tension.     

A dynamic quality control approach by improving dominant factors based on improved principal component analysis

Process variables in manufacturing process are critical to the final quality of product, especially in continuous process. Their abnormal fluctuations may cause many quality problems and lead to poor product quality. Against this background, this paper proposes a dynamic quality control approach by improving dominant factors (DFs) based on improved principal component analysis (iPCA). Firstly, the generation of iPCA is illustrated to identify the DFs which lead to quality problems. Then, a quality prediction model for improving DFs is proposed based on modified support vector machine (SVM). An incremental weight is introduced in SVM to improve its sparsity and increase the accuracy of quality prediction. Thus, the product quality can be guaranteed by controlling the DFs dynamically. Finally, a case study is provided to verify the feasibility and applicability of proposed method. The research is expected to provide some guidance for continuous process.