A novel grey‐based feature ranking method for feature subset selection

Abstract

In this paper, a novel grey‐based feature ranking method for feature subset selection is proposed. The classification effectiveness of each attribute of a specific classification problem is proposed and then each attribute can be ranked. Features with higher classification effectiveness are more important and relevant and thus considered as the final feature subset for pattern classification. Experiments performed on various application domains are reported to demonstrate the performance of the proposed approach. The proposed approach yields better performance than other existing feature subset selection methods and is helpful for improving the classification accuracy in pattern classification.     

A microprocessor‐based electrohydraulic servo system

Abstract

A microprocessor‐based electrohydraulic servo system has been constructed and tested. It is implemented with an 8‐bit single‐chip microcomputer to control a hydraulic motor. The control algorithm is based on variable structure control principles. The experimental results show that the system is under good control and possesses a great potential for electrohydraulic servo control.     

On the performance of a class‐4 partial response digital communication system

Abstract

The dark conductivity of phosphorus‐doped amorphous‐silicon alloys (a‐Si:H:F) prepared by the RF plasma decomposition of a gaseous mixture of SiF₄, H₂ and diluted PH₃ is extremely high; it exceeds 10 (O‐cm)^‐1 with only a small amount of PH₃ (～500 ppm) added in the gas phase. These doping characteristics represent a significant improvement over the doping characteristics of a‐Si:H alloys prepared by a glow‐discharge of SiH₄. The improvement was found to be due to the fact that P‐doped a‐Si:H:F contains microcrystallites which are embedded in an amorphous network. The percolation process in these two‐phase systems gives rise to high conductivity. We have used transmission electron microscopy (TEM) and diffraction (TED) to determine the critical surface fraction, ρ_c, of crystallinity at the onset of extended conduction. The measured ρ_c is approximately 0.46. This percolation limit provides a basis for the analysis of the electrical properties of P‐doped a‐Si:H:F.     

A transceiver system for dual‐simplex high‐bit‐rate digital subscriber lines

Abstract

High bit‐rate digital subscriber lines (HDSL) technology is a new technology that may provide bi‐directional transmission at a rate of 1.544 Mb/s in conventional copper wires. A transceiver system for dual‐simplex (DSX)‐HDSL is presented. Simulation results show that the DSX‐HDSL system combined with simple pair‐selection can provide 18Kft/24AWG service distance without line repeaters. In the presented DSX‐HDSL transceiver, 2B1Q code with (1‐D) precoding is used to reduce the inter‐symbol interference (ISI) and the dynamic range of signal. Hence, a 12‐bit or less A/D converter can satisfy the performance requirement. In addition, another switchable (1‐D) filter is used in the receiver to shorten the duration of channel response, therefore a (5, 32) hybrid‐decision‐feedback‐equalizer (DFE) can obtain an adequate performance.     

Attacking the bottleneck in a bus‐based multiprocessor system

Abstract

Connection through a single bus is the simplest architecture for multiprocessor systems. However, as the number of processors scales up, the common bus will eventually become the bottleneck of the system. Three different bus‐based architectures, multiprocessors without local memories, multiprocessors with single port local memories, and multiprocessors with dual port memories, are analyzed in this paper. It shows to what degree increasing the local execution probability of a multiprocessor system with dual port memories can relieve the load of the common bus and thus increase the effective computing power. A multiprocessor operating system (MOS) designed at National Chiao Tung University (NCTU) has suffered bottleneck trouble in the previous year. Problems in MOS are discussed. A new design of this operating system kernel, MOS*, is then proposed. Performance of these two different designs are evaluated and compared by simulation. The simulation results show that MOS*, with a localizing process strategy, can increase effective computing power 30–100 percent. The saturation point of MOS* is also explored in the paper.     

Design of a double microprocessor‐based on‐line process control system

Abstract

A numerical technique for integrating the full Navier‐Stokes and diffusion equations through an initial value problem has been used to investigate the time development of a line buoyant source issuing in a density‐stratified environment. The basic physical features and some structures of the interactions of the motion at the intermediate mixing region are obtained. Results show that the stratification tends to inhibit the flow development of the buoyant source and to encourage the formation of a recirculatory vortex on the lower region near the source and the upper region.     

A frequency‐locked position servo control system by microprocessor‐based slope‐varied technique

Abstract

A microprocessor‐based slope‐varied frequency‐pumped controller (μP‐SVFPC) for improving the locking performance of the frequency‐locked position servo control system (FLPS) is presented. The presented slope‐varied pump technique is to perform the position control process fast for a long distance servo, while nearly similar acquisition times for different distance servos are obtained during the servo range. The motion profiles for system locking are adaptively generated according to the coming frequency error. No motion profiles are required to be pre‐installed in the controller. A prototype of μP‐FLPS is realized, simulated, and tested. Computer simulation and experimental result confirm that the system acquisition times of μP‐FLPS for short, middle, and long distance servos are nearly similar to each other. In comparison with the basic FLPS system, the acquisition times of the presented μP‐FLPS for the middle and long distance servos are improved by about 58% and 85%, respectively.     

A study of the spatial distribution of transportation‐an alternative approach and evaluation

Abstract

This study intends to investigate a calibration procedure for a proposed combined trip generation and distribution model which is based on the concept of accessibility. Apart from the proofs of the existence and uniqueness of the solution, the computation efficiency is evaluated by using Cesario's data (1). The calibration procedure is further tested with empirical data which is obtained from an actual transportation survey carried out in Kaohsiung City of Taiwan, the Republic of China.     

Does digital imaging decrease patient dose? A pilot study and review of the literature

The potential for decreasing patient dose is one of the main arguments for the justification of the cost of digital imaging equipment. However, the literature review with respect to patient doses using digital imaging modalities, presents conflicting results. During this study, patients' entrance surface doses were measured for three simple radiographic examinations, in European centres equipped with a computed radiography digital system. Results showed that doses between centres varied from 30% for chest LAT to 250% for chest PA examination. With the digital image quality criteria still under discussion, and with the post-processing parameters and/or image documentations varying, any dose comparisons between conventional/digital systems, as well as dose comparisons between different centre using digital units, are difficult. Clinical trials are required in order to define reference levels associated with quality of digital image necessary to address specific clinical requirements.     

A job‐plan based performance evaluation for construction value engineering study

Abstract

Value Engineering can reduce costs and enhance the value of projects. Currently, the acceptance rate of Value Engineering Study (VES) recommendations and total potential savings are considered the principal performance indicators of a VES. In reality the success of a VES depends on numerous interrelated factors not easy for a VES team to control. However, a study team can ensure the success of a VES by fully implementing a VES job plan. Thus, realizing a job plan is a principal contribution toward insuring the success of the VES. This study presents a novel model that is able to evaluate the performance of a VES for a construction project. Two questionnaires, distributed to VE experts, were used to collect data needed for this research. Factor analysis, AHP, and SWAM were applied to build the VES performance evaluation model which consists of six evaluation groups and thirty‐two evaluation items. A real‐life VES for a construction project was then analyzed using the proposed model to demonstrate its usefulness in performance assessment. Defects of the VES were identified and suggestions were provided for the particular VES. The proposed model can be used by VES teams for self‐diagnosis, improvement, and motivation in achieving enhanced performance.     

A study on the transmission loss of straight‐through type reactive mufflers

Abstract

The following study presents a newly developed approach for modeling perforated muffler components, such as partially perforated extended inlet/outlet elements. After evaluating the transfer matrices of all sub‐elements, the transfer matrices product is obtained by multiplication of partially perforated extended inlet/outlet elements. For acoustic impedance in the linear regime, a closed form solution of the partially perforated intruding tube muffler transmission loss was first obtained. In the case of zero mean flow, the predicted results for the various muffler configurations strongly corresponds to the measured values within the limitations of the one‐dimensional theory. By tuning the lengths and associated physical parameters to the in‐situ case of various tubular elements, one can achieve rapid and economical modeling of frequently used commercial reactive mufflers as well as mufflers for other industrial applications can be achieved. This aeroacoustic modeling ability is very useful for vehicular muffler designer especiallly during the preliminary design stages.     

Sub‐band coding of digital images

Abstract

An efficient sub‐band coding method for encoding images is presented in this paper. In this method a frequency band decomposition of the image is carried out by means of two‐dimensional separable quadrature mirror filters (QMF's), which split the image spectrum into sixteen uniform sub‐bands. In the coding process, we employ special quantizers and encoding algorithms which are designed according to the characteristics (including the visual perceptual property) of the sub‐bands to quantize and to encode these subimages, separately. The simulation results are presented in terms of average bit rates and the quality (in subjective as well as mean squared senses) of the reconstructed images. These results indicate that a good quality reproduction can be achieved at high compression rates. The paper also shows that a seven‐band decomposition has very high performance in quality, compression rate, and economy.     

Development of machine learning‐based real time scheduling systems: using ensemble based on wrapper feature selection approach

There are two items that significantly enhance the generalisation ability (i.e. classification accuracy) of machine learning‐based classifiers: feature selection (including parameter optimisation) and an ensemble of the classifiers. Accordingly, the objective in this study is to develop an ensemble of classifiers based on a genetic algorithm (GA) wrapper feature selection approach for real time scheduling (RTS). The proposed approach can better enhance the generalisation ability of the RTS knowledge base (i.e. classifier) in comparison with three classical machine learning‐based classifier RTS systems, including the GA‐based wrapper feature selection mechanism, in terms of the prediction accuracy of 10‐fold cross validation as measured according to all the performance criteria. The proposed ensemble classifier RTS also provides better system performance than the three machine learning‐based RTS systems, including the GA‐based wrapper feature selection mechanism and heuristic dispatching rules, under all the performance criteria, over a long period in a flexible manufacturing system (FMS) case study.     

Can the average glandular dose in routine digital mammography screening be reduced? A pilot study using revised image quality criteria

There is a need for tools that in a simple way can be used for the evaluation of image quality related to clinical requirements in mammography. The aim of this work was to adjust the present European image quality criteria to be relevant also for digital mammography images, and to use as simple and as few criteria as possible. A pilot evaluation of the new set of criteria was made with mammograms of 28 women from a General Electric Senographe 2000D full-field digital mammography system. One breast was exposed using the standard automatic exposure mode, the other using about half of that absorbed dose. Three experienced radiologists evaluated the images using visual grading analysis technique. The results indicate that the new quality criteria can be used for the evaluation of image quality related to clinical requirements in digital mammography in a simple way. The results also suggest that absorbed doses for the mammography system used may be substantially reduced.     

Insulation status assessment of cast‐resin current transformers based on digital partial discharge measurement

Abstract

Three cast‐resin current transformers with different PD inception voltages of 43kV, 24kV and 12kV, respectively, are used in accelerated aging tests during which PD information is detected and measured. Lastly, the real measurement results of two cast‐resin current transformers are used to examine the feasibility of the proposed determination rules. Our study shows that the slop of the average discharge amount's development trend is more suitable for insulation status determination than other parameters, and said slop's accuracy and practicality is valuable for continuous research in insulation aging.     

Electrochemical study of the graphite—HNO3 system

The anodic oxidation of highly oriented pyrolytic graphite in 50 to 98% HNO₃ was studied in a galvanostatic mode at a current of 1.5 mA. At HNO₃ concentrations from 55 to 98%, the potential-vs.-charge curves showed steplike behavior, and the number of steps increased with decreasing acid concentration, reflecting the successive formation of stage III, II, and I graphite nitrate. Electrochemical synthesis of stage I graphite nitrate was shown to be possible in 75 to 98% HNO₃. The anodic oxidation in 60 to 70% HNO₃ resulted in a stage I + II mixture, and that in 55% HNO₃ yielded a mixture of stage II and a defect graphite phase. In 50% HNO₃, no intercalation compounds were formed. The specific charge required for the formation of stage I graphite nitrate was determined as a function of HNO₃ concentration. The assumption is made that, in dilute HNO₃ solution containing significant amounts of water, rapid electrochemical oxidation leads to the formation of graphite oxides     

Automatically detecting endocardium and epicardium of left ventricle by digital image processing for 2‐D echocardiography

Abstract

Detecting the endocardium and epicardium of the left ventricle is important for further quantitative analysis of cardiac functions and three‐dimensional reconstruction. However, to detect the boundaries automatically is difficult. In this paper, we proposed a novel, single frame method, based on binary morphology and region growing techniques, to detect the boundaries of the left ventricle automatically except an A.O.I. (Area Of Interest) adjustment operation must be performed during the process of getting image data from video tape and storing it onto the disk. The method is suited for boundary detection required in three‐dimensional reconstruction for the observation of congenital abnormalities of ventricular septum or for generating cross sectional images of arbitrary orientation. Moreover, the method may be improved by further processings for accurate endocardial and epicardial boundary estimation for quantitative cardiac function evaluations.