Search

Digital technologies have been used for a vast amount of bibliometric analysis research. Although these technologies have made scientific investigation more accessible and efficient, scholars now face the daunting task of sifting through an overwhelming number of documents. This study aims to identify bibliometric research analysis's primary topics, categories, and latent topics from a global perspective. This study utilized topic modeling techniques to analyze the abstracts of 16,039 eligible papers published between 1977 and 2023 in the Scopus database. Through the use of Latent Dirichlet Allocation (LDA) topic modeling, the study was able to identify four distinct research topics and observe how they have evolved over time. The research topic has shifted its focus from individual concepts and words to relationships between nodes and conceptual, intellectual, and social structures. The study’s findings have significant implications for bibliometric analysis-related research, providing valuable insights into trends and patterns in bibliometric analysis content within large digital article archives. The LDA has proven to be an efficient tool for analyzing these trends and patterns quickly. This study's novel approach considers factors for word embedding usage and optimal topic numbers. It focuses on a full understanding of the LDA results and combines statistical analysis, domain knowledge, and temporal exploration to better understand how data structures work. Doi: 10.28991/HIJ-2024-05-02-07 Full Text: PDF

Qiang Ye,1 Guoping Huang,1 Qin Hu,1 Qin Man,2 Xiaoying Hao,3 Liangyan Liu,4 Qiang Zhong,1 Zhao Jin2 1Department of Clinical Laboratory, West China Second University Hospital, Southern Sichuan Women’s and Children’s Hospital, Zigong, Sichuan, 643000, People’s Republic of China; 2Department of Prenatal Diagnosis Center, West China Second University Hospital, Southern Sichuan Women’s and Children’s Hospital, Zigong, Sichuan, 643000, People’s Republic of China; 3Department of Ultrasound, West China Second University Hospital, Southern Sichuan Women’s and Children’s Hospital, Zigong, Sichuan, 643000, People’s Republic of China; 4Department of Obstetrics, West China Second University Hospital, Southern Sichuan Women’s and Children’s Hospital, Zigong, Sichuan, 643000, People’s Republic of ChinaCorrespondence: Zhao Jin, Department of Prenatal Diagnosis Center, West China Second University Hospital, Southern Sichuan Women’s and Children’s Hospital, No. 49 Da Huang Tong Road, Da’an District, Zigong, Sichuan, 643000, People’s Republic of China, Tel +86-13990094008, Email Jinzhao_work@163.comObjective: This study was to evaluate the performance of noninvasive prenatal testing (NIPT) in detecting fetal chromosome disorders in pregnant women.Methods: From October 1st, 2017, to December 31th, 2022, a total of 15,304 plasma cell free DNA-NIPT samples were collected for fetal chromosome disorders screening. The results of NIPT were validated by confirmatory invasive testing or clinical outcome follow-up. Further, NIPT performance between low-risk and high-risk groups, as well as singleton pregnancy and twin pregnancy groups was compared. Besides, analysis of 111 false-positive cases was performed.Results: Totally, NIPT was performed on 15,086 eligible venous blood samples, of which 179 (1.19%) showed positive NIPT results and 68 were further validated to be true positive samples via confirmatory invasive testing or follow-up of clinical outcomes. For common chromosome aneuploidies, sex chromosome abnormalities (SCA) and other chromosomal aneuploidies, the detection sensitivities of NIPT were all 100%, the specificities were 99.87%, 99.70%, and 99.68% and the positive predictive values (PPVs) were 65.45%, 31.82%, and 10.91%, respectively. No statistically significant variance in detection performance was observed among 2987 high-risk and 12,099 low-risk subjects, as well as singleton and twin pregnancy subjects. The concentration of cell-free fetal DNA of 111 false-positive cases ranged from 5.5% to 33.7%, which was higher than the minimum requirement of NIPT.Conclusion: With stringent protocol, NIPT shows high sensitivity and specificity for detecting fetal chromosome disorders in a large-scale clinical service, helping improving overall pregnancy management.Keywords: noninvasive prenatal testing, fetal chromosome disorders, high risk, twin pregnancy, performance evaluation

This paper presents the results of a comprehensive experimental study on the flexural performance of ballastless discrete precast slab tracks with two alternative reinforcement types. These are the precast slab tracks produced using ordinary reinforcement [nonposttensioned (NPT)] and the precast slab tracks produced using post-tensioned (PT) reinforcement. The study aims to compare the flexural performances of NPT- and PT-type slab tracks using three-point bending tests, even though they continuously sit on the ground with different rigidities in real-life applications. The tests performed on four full-scale slab tracks in the longitudinal and transversal directions resulted in the first cracking and the ultimate loads were greater in PT specimens. Also, the maximum crack widths and residual displacements of PT specimens were smaller. Although the aforementioned performance parameters of NPT-type slab tracks are relatively behind those of PT-type slab tracks, their overall response is still acceptable, with the advantages of easier production and lower cost. [ABSTRACT FROM AUTHOR]

Pansharpening is the fusion of panchromatic (PAN) and multispectral (MS) images to obtain a high spectral and spatial resolution image. Various metrics are introduced to assess the performance of different algorithms of pansharpening. This paper proposes a new metric for spectral quality evaluation of fused images. In the proposed method, spectrum vector of each pixel of fused image is compared to corresponding spectrum of reference image. Area of difference between two spectra is measured, and by applying this process to all pixel vectors of the fused image and taking an average over obtained values, spectral distortion of whole image is obtained. To investigate the efficiency of the proposed index, deliberate spectral distortion is applied to fused image and the proposed metric's ability to detect distortion is examined. Experimental results on real remote sensing images demonstrate the superior performance of the proposed metric compared to other existing metrics.

This paper describes a study on the power and energy consumption estimation models that have been defined to facilitate the development of ultra-low power embedded applications. During the study, various measurements have been carried out on the instruction and application level to challenge the models against empirical data. The study has been performed on the multicore heterogeneous hardware platform developed for ultra-low power Digital Signal Processors (DSP) applications. The final goal was to develop a tool that can provide insight into power dissipation during the execution of embedded applications, so that one can refactor the source code in an energy-efficient manner, or ideally to develop an energy-aware C compiler. The side effect of the research presents interesting insight into how the custom hardware architecture influences power dissipation. The selected platform has been chosen simply because it represents R&D state of the art ultra-low power hardware used in hearing aids. The presented solution has been developed and tested in an Eclipse environment using Java programming language. [ABSTRACT FROM AUTHOR]

Performance of modern automated pattern recognition (PR) systems is heavily influenced by accuracy of their feature extraction algorithm. Many papers have demonstrated uses of deep learning techniques in PR, but there is little evidence on using them as feature extractors. Our goal is to contribute to this field and perform a comparative study between classical used methods in feature extraction and deep learning techniques. For that, a biometric recognition system, which is a PR application, is developed and evaluated using a proposed evaluation metric called expected risk probability. In our study, two deeply learned features, based on PCANet and DCTNet deep learning techniques, are used with two biometric modalities that are palmprint and palm-vein. Subsequently, the efficiency of these techniques is compared with various classical feature extraction methods. From the obtained results, we drew our conclusions on a very positive impact of deep learning techniques on overall recognition rate, and thus these techniques significantly outperform the classical techniques. © 2018 SPIE and IS&T [DOI: 10.1117/1.JEI.27.3.033008] [ABSTRACT FROM AUTHOR]

The objective of this work is to construct a performance evaluation model to provide support to a production director in the management of the productive operations of a furniture industry. In this sense, we sought through the Multicriteria Decision Aid Constructivist Methodology (i) to identify the factors considered important by the production director for evaluating the performance of productive operations, (ii) to measure each criterion of performance evaluation, (iii) to integrate the criteria to allow the evaluation of organizational performance at the tactical and strategic levels and (iv) to develop a process to manage the actions of productive operations improvement.As a research result we have a performance evaluation model for supporting the management of the productive operations. We conclude that the MCDA-C allowed for building the knowledge of the decision-maker on how to identify and measure the critical variables and manage the performance of the productive operations.

Emergence and evolution of Wireless Sensor Networks (WSNs) opened the door for the development of many applications. Mobile Wireless Sensors Networks (MWSNs) is a subclass of WSNs in which some or all sensors are mobile. Although such mobility has benefits for extending network coverage, the existence of nodes mobility imposes challenges in the data delivery process as connectivity changes dynamically. This issue is exacerbated when nodes move in uncontrollable manner, e.g. mounted on helmets of factory workers or on vehicles. Existing WSNs routing protocols are mainly designed to support static or semi-dynamic scenarios. Due to the similarity between MWSNs and Mobile Ad-hoc Networks (MANETs), existing MANET routing protocols can be used for this purpose. In this paper, we use ns2 to evaluate the performance of two MANET routing protocols, GPSR and AOMDV, in the field of MWSNs with a location-based sensing application assuming the nodes move in an uncontrollable manner. We use metrics such as packet delivery ratio, routing overhead, hop count, and energy consumption to test protocols performance. We also use a utility function to estimate the performance of the application. We find that the geographic-based routing, GPSR, works better than AOMDV due to its lower routing protocol overhead. [ABSTRACT FROM AUTHOR]

Bu çalışmada, Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik-2007 (DBYBHY-2007) ye göre boyutlandırılan altı katlı dış merkez çaprazlı bir çelik perdenin deprem performansı, zaman tanım alanında doğrusal olmayan hesap yöntemi kullanılarak değerlendirilmiştir. Bu değerlendirmede göreli kat ötelemeleri, kat kesme kuvvetleri, çapraz ve kolonların iç kuvvet istemleri ile bağ kirişi kesme kuvveti ve dönme istemleri dikkate alınmıştır. Zaman tanım alanında doğrusal olmayan analizler yedi adet deprem ivme kaydı kullanılarak gerçekleştirilmiştir. Analizler sonucu elde edilen istemlerin ortalama değerleri esas alınarak dış merkez çaprazlı çelik perdelerin kullanıldığı orta yükseklikteki binalar için DBYBHY-2007'de öngörülen kapasite tasarımı yaklaşımının yeterliliği araştırılmıştır.

Bu çalışmada, Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik-2007 (DBYBHY-2007) ye göre boyutlandırılan altı katlı dış merkez çaprazlı bir çelik perdenin deprem performansı, zaman tanım alanında doğrusal olmayan hesap yöntemi kullanılarak değerlendirilmiştir. Bu değerlendirmede göreli kat ötelemeleri, kat kesme kuvvetleri, çapraz ve kolonların iç kuvvet istemleri ile bağ kirişi kesme kuvveti ve dönme istemleri dikkate alınmıştır. Zaman tanım alanında doğrusal olmayan analizler yedi adet deprem ivme kaydı kullanılarak gerçekleştirilmiştir. Analizler sonucu elde edilen istemlerin ortalama değerleri esas alınarak dış merkez çaprazlı çelik perdelerin kullanıldığı orta yükseklikteki binalar için DBYBHY-2007'de öngörülen kapasite tasarımı yaklaşımının yeterliliği araştırılmıştır.

In this paper we proposed a smart interference rejection filter in TH-PPM UWB system, which improves the system's error probability for an order of magnitude in case of high power OFDM interference. The smart filter is based on an adaptive transversal filter. Based on the fulfillment of certain conditions, the filter activates or deactivates some parts of it.

In this work, design of an Android-based augmented reality application is presented and particularly its performance is analyzed in terms of resource usage in comparison to similar applications. The application displays merchant, branch information of one of the Turkish banks, as well as related sales campaigns of the merchants on the screen that are within the proximity of the user's location. The developed application uses GPS, compass, gyroscope, accelerometer sensors and it utilizes an accurate tagging algorithm. We examine the resource and battery consumption of the application. Accordingly, we propose methods for improving the resource usage. The proposed improvements reduce the resource consumptions up to 35% and the application performs considerably well compared to the state of the art commercial applications. We believe that the suggested improvements can be useful for other sensor-based mobile augmented reality applications. [ABSTRACT FROM AUTHOR]

The popularity of the index funds as an investment option has increased manifolds ever since they were introduced. This is primarily because of the merits that the investor enjoys through passive style of funds management. This includes the low cost involved in managing such funds and the significant tax savings. Most of the researchers have compared the performance of the actively managed funds with that of index funds. However the index funds of US and for that reason other parts of the world are different from that of India. Unlike other countries in India the benchmark indices comprise of very less number of securities and thus are unable to represent the entire economy. So in Indian context comparison of performance of actively managed funds with index funds is not logical. Therefore this paper attempts to make an intra-class performance evaluation of some Indian index funds based on some statistics. The study includes the use of graphical interpretations coupled with statistical tools like R-square and tracking error values. Two models of tracking error have been employed to test empirically the performance of the selected index funds. The study is useful for those interested in mutual funds, which includes researchers, academicians, and financial advisors. The paper suits the requirement and the situations prevalent in Indian economy during the period under study. [ABSTRACT FROM AUTHOR]

Logically centralized nature of the controller in Software-defined Networking (SDN) makes it vulnerable to various adversarial attacks. These attacks have capabilities to degrade the performance of the managed network or bring it down in the worst case. For this reason, a large-scale deployment of SDN needs evaluation of the impact of adversarial attacks on network services. In this work, we implement various attacks in SDN and analyze their impact on the performance of web-based services running over it. Prior to that, we briefly discuss different kinds of vulnerabilities and threats in SDN. We consider the connection set-up latency and loss, for web-client requests, as metrics for the evaluation. We observe a significant degradation in the performances of web services, in terms of response time and availability, in the presence of implemented attacks. [ABSTRACT FROM AUTHOR]

The reporting of comprehensive income is becoming increasingly important. The new version of IAS 1 (the so called IAS1-revised) issued by IASB on September 2007 provides the mandatory reporting of other comprehensive income items for the EU listed companies. This circumstance is of particular relevance in the Italian context, characterized by a strong historical cost accounting model and by concentrated ownership publicly traded companies. This study aims to examine the potential impact of unrealized gains and losses reporting on entities performance ratio, and thus on investors’ decision process, by investigating its effects on Italian listed entities. The results show that the first time adoption of comprehensive income reporting does significantly affect Italian listed entities performance, notwithstanding the apparent irrelevant spread existing between net income and comprehensive income book values. [ABSTRACT FROM AUTHOR]

SCADA control systems are the keystone for reliable performance optimization of wind farms. Processing into knowledge the amount of information they spread is a challenging task, involving engineering, physics, statistics and computer science skills. The present work deals with the effects on the efficiency of turbine inability of optimal aligning to the wind direction, due to meandering wind caused by wakes. The approach is tested on a judiciously chosen cluster of turbines of a wind farm sited in southern Italy. By a post-processing method based on discretization of nacelle position measurements, a set of dominant patterns of the cluster is identified. The patterns associated to best performances are individuated and it is shown that they correspond to non-trivial alignment to wind direction. [ABSTRACT FROM AUTHOR]

The purpose of this study is to discuss the impact of financial innovations on the tourism enterprises in Istanbul. In this context, a qualitative research method is used. The restaurants, five star hotels, group A travel agencies active in Istanbul constitute the universe of the research. This research is carried out in Istanbul, one of the metropolis cities of Turkey. In this regard, 6 businesses including 2 hotels, 2 restaurants, 2 travel agencies constitute the unit of analysis. By creating the data form, the data was obtained from the senior managers of the enterprises determined beforehand. As a result of the research, it came up that using or creating financial innovations in the hotel enterprises effects performance. Also, it emerged that businesses take into account their financial, customer and internal processes, partially learning and development. That the research is conducted in one city only and the data is acquired from only six businesses comprise the limitation of this research. [ABSTRACT FROM AUTHOR]

Agility is regarded as one of the core capabilities and the developing trend of supply chains and their enterprises. Along with the development of economical globalization, supply chain management and containerization as well as container ports as a part of supply chain take more roles like logistics or distribution centers. Under this background, the container terminal should have superior response and develop agility. The main goal of this paper is to emphasize and illustrate the importance and imminence of implementing agility in container terminals. To achieve this goal, the analysis of the economies of scale in the container terminal is presented. In this paper, however, more attention will be paid to agile service oriented shipping companies. The concept and characters of agile service in the container terminal is illustrated. The paper also focuses on the agile organizational structure of the container terminal. Finally, the fuzzy quality synthetic evaluation method is given to evaluate the performance level of agile service in container terminal oriented shipping companies. [ABSTRACT FROM AUTHOR]

This paper investigates the random channel access mechanism specified in the IEEE 802.16 standard for the uplink traffic in a point-to-multipoint (PMP) network architecture. An analytical model is proposed to study the impacts of the channel access parameters, bandwidth configuration and piggyback policy on the performance. The impacts of physical burst profile and non-saturated network traffic are also taken into account in the model. Simulations validate the proposed analytical model. It is observed that the bandwidth utilization can be improved if the bandwidth for random channel access can be properly configured according to the channel access parameters, piggyback policy and network traffic. [ABSTRACT FROM PUBLISHER]

In this paper, we develop a model to predict the performance of synchronous discrete event simulation. Our model considers the two most important factors for the performance of synchronous simulation: load balancing and communication. The effect of load balancing in a synchronous simulation is computed using probability distribution models. We derive a formula that computes the cost of synchronous simulation by combining a communication model called LogGP and computation granularity. Even though the formula is simple, it is effective in capturing the most important factors for the synchronous simulation. The formula helps us to predict the maximum speed up achievable by synchronous simulation. In order to examine the prediction model, we have simulated several large ISCAS logic circuits and a simple PCS network simulation on an SGI Origin 2000 and Terascale Computing System (TCS) at the Pittsburgh Supercomputing Center. The results of the experiment show that our performance model accurately predicts the performance of synchronous simulation. The performance model developed is used to analyze the effect of several factors that may improve the performance of synchronous simulation. The factors include problem size, load balancing, granularity, communication overhead, and partitioning. [ABSTRACT FROM AUTHOR]

This paper aims at automatic understanding of online handwritten mathematical expressions (MEs) written on an electronic tablet. The proposed technique involves two major stages: symbol recognition and structural analysis. Combination of two different classifiers have been used to achieve high accuracy for the recognition of symbols. Several online and of line features are used in the structural analysis phase to identify the spatial relationships among symbols. A context-free grammar has been designed to convert the input expressions into their corresponding IbX strings which are subsequently converted into MathML format. Contextual information has been used to correct several structure interpretation errors. A new method for evaluating performance of the proposed system has been formulated. Experiments on a dataset of considerable size strongly support the feasibility of the proposed system. [ABSTRACT FROM AUTHOR]

Arc segmentation plays an important role in the process of graphics recognition from scanned images. The GREC arc segmentation contest shows there is a lot of room for improvement in this area. This paper proposes a multiresolution arc segmentation method based on our previous seeded circular tracking algorithm which largely depends on the OOPSV model. The newly-introduced multiresolution paradigm can handle arcs/circles with large radii well. We describe new approaches for arc seed detection, arc localization, and arc verification, making the proposed method self-contained and more efficient. Moreover, this paper also brings major improvement to the dynamic adjustment algorithm of circular tracking to make it more robust. A systematic performance evaluation of the proposed method has been conducted using the third-party evaluation tool and test images obtained from the GREC arc segmentation contests. The overall performance over various arc angles, arc lengths, line thickness, noises, arc-arc intersections, and arc-line intersections has been measured. The experimental results and time complexity analyses on real scanned images are also reported and compared with other approaches. The evaluation result demonstrates the stable performance and the significant improvement on processing large arcs/circles of the MAS method. [ABSTRACT FROM AUTHOR]

Data storage plays an essential role in today''s fast-growing data-intensive network services. New standards and products emerge very rapidly for networked data storage. Given the mature Internet infrastructure, the overwhelming preference among the IT community recently is using IP for storage networking because of economy and convenience. iSCSI is one of the most recent standards that allow SCSI protocols to be carried out over IP networks. However, there are many disparities between SCSI and IP in terms of protocols, speeds, bandwidths, data unit sizes, and design considerations that prevent fast and efficient deployment of storage area network (SAN) over IP. This paper introduces SCSI-to-IP cache storage (STICS), a novel storage architecture that couples reliable and high-speed data caching with low-overhead conversion between SCSI and IP protocols. A STICS block consists of one or several storage devices and an intelligent processing unit with CPU and RAM. The storage devices are used to cache and store data while the intelligent processing unit carries out the caching algorithm, protocol conversion, and self-management functions. Through the efficient caching algorithm and localization of certain unnecessary protocol overheads, STICS can significantly improve performance, reliability, and scalability over current iSCSI systems. Furthermore, STICS can be used as a basic plug-and-play building block for data storage over IP. Analogous to “cache memory” invented several decades ago for bridging the speed gap between CPU and memory, STICS is the first-ever “cache storage” for bridging the gap between SCSI and IP making it possible to build an efficient SAN over IP. We have implemented software STICS prototype on Linux operating system. Numerical results using popular benchmarks such as vxbench, IOzone, PostMark, and EMC''s trace have shown a dramatic performance gain over the current iSCSI implementation. [Copyright &y& Elsevier]

In this paper, the static and seismic performance of some short span reinforced concrete arch bridges, before and after strengthening interventions, are evaluated. To verify whether retrofit strategies for the considered arch bridges, which were designed for resisting under permanent and service actions, were adequate for earthquake resistance, seismic analyses of the as-built model of the structures have been undertaken. To account for multiple input effects on arches, induced by out-of-phase motions at foundation levels as well as different boundary conditions at structural supports, the seismic response of the structures under correlated horizontal and vertical multiple excitations is calculated. The effects on arch bridges of conventionally used uniform input and partially correlated multiple inputs with phase shifts are compared. In all cases, the results are discussed with particular reference to the influence of structural configuration, secondary systems, cross-section thickness of the arch, and retrofit interventions. [ABSTRACT FROM AUTHOR]

An attempt is made to realize highly reliable multicast communications without modifying the TCP protocol, which is now the most widely used in the Internet, and TCP multicast using a GRA (generic router assist) router is proposed. The characteristics of this multicast communications are evaluated, and it is shown that the overall throughput of multicast communications is governed by the bottleneck link in the transmission band. An attempt is made to improve the performance of multicast communications with a bottleneck link, and an environment-adaptive multicast communication scheme is proposed, in which the multicast tree is partitioned at the bottleneck link, and TCP multicasting is performed for each subtree. Performance evaluation by simulation shows that the proposed method alleviates the effect of the bottleneck link on the overall multicast and that the performance of the multicast as a whole can be improved. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 28–38, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10161 [ABSTRACT FROM AUTHOR]

In this paper, we propose an enhanced concurrency control algorithm that maximizes the concurrency of multidimensional index structures. The factors that deteriorate the concurrency of index structures are node splits and minimum bounding region (MBR) updates in multidimensional index structures. The properties of our concurrency control algorithm are as follows: First, to increase the concurrency by avoiding lock coupling during MBR updates, we propose the PLC (Partial Lock Coupling) technique. Second, a new MSR update method is proposed. It allows searchers to access nodes where MBR updates are being performed. Finally, our algorithm holds exclusive latches not during whole split time but only during physical node split time that occupies the small part of a whole split process. For performance evaluation, we implement the proposed concurrency control algorithm and one of the existing link technique based algorithms on MIDAS-Ill that is a storage system of a BADA-IV DBMS. We show through various experiments that our proposed algorithm outperforms the existing algorithm in terms of throughput and response time. Also, we propose a recovery protocol for our proposed concurrency control algorithm. The recovery protocol is designed to assure high concurrency and fast recovery: [ABSTRACT FROM AUTHOR]

ABSTRACT: The balanced scorecard is a new tool that complements traditional measures of business unit performance. The scorecard contains a diverse set of performance measures, including financial performance, customer relations, internal business processes, and learning and growth. Advocates of the balanced scorecard suggest that each unit in the organization should develop and use its own scorecard, choosing measures that capture the unit's business strategy. Our study examines judgmental effects of the balanced scorecard--specifically, how balanced scorecards that include some measures common to multiple units and other measures that are unique to a particular unit affect superiors' evaluations of that unit's performance. Our test shows that only the common measures affect the superiors' evaluations. We discuss the implications of this result for research and practice. [ABSTRACT FROM AUTHOR]

We investigate if earnings forecast accuracy matters to security analysts by examining its association with analyst turnover. Controlling for firm- and time-period effects, forecast horizon and industry forecasting experience, we find that an analyst is more likely to turn over if his forecast accuracy is lower than his peers. We find no association between an analyst's probability of turnover and his absolute forecast accuracy. We also investigate another observable measure of the analyst's performance, the profitability of his stock recommendations. There is no statistical relation between the absolute or relative profitability of an analyst's stock recommendations and his probability of turnover. We interpret our findings as indicating that forecast accuracy is important to analysts. [ABSTRACT FROM AUTHOR]

Since the early 1970s, the application of queueing network models to computer system performance analysis has generated considerable interest. The period since has seen considerable progress in advances both in the fundamental theory and in practical experience. Other papers in this special issue have surveyed the state of the art. This note attempts to provide a condensed statement as to where we are and, as much as possible, to indicate areas of future research with high potential. [ABSTRACT FROM AUTHOR]

Performance evaluation of VLSI circuits has been studied widely following the progress of VLSI technology. In these studies, the amount of material as well as the wire routing lengths required for the VLSI layouts for sorting circuits, FFT circuits, interconnection circuits, and so on, have been discussed. These discussions are based on a fact that the wire muting controls the VLSI performance, but they all concentrate on conventional two-dimensional (2-D) VLSI circuits. By contrast, new integration technology, i.e., so-called 3-D VLSI technologies, have been developed to overcoat the bathers to the progress of 2-D integration technology. This paper discusses the performance evaluation of FFT circuits based on 2-D VLSI technology as well as 3-D VLSI technology. As the evaluation results, the amount of material can be reduced about one O(N-1/2 log N)-th to one O(N-1/2 log-2 N)-th by using 3-D construction rather than the conventional 2-D VLSI circuit. Furthers more, the optimum FFT circuit basal on the AT² complexity for 2-D integrated circuits cannot always be an optimum circuit basal on the V²T³ complexity for 3-D integrated circuits. Therefore, it will be necessary to reevaluate each circuit based on the V²T³ complexity to fabricate it as a 3-D VLSI system. [ABSTRACT FROM AUTHOR]

This paper presents an approximate analysis of the maximum throughput of an HDLC-based data link protocol for a bridled network. To model an end-to-end data link connection, which is connected across multiple transmission lines and bridge processors, a specific server, denoted as a bottleneck server, is defined. This is identified as the server (i.e., transmission line or processor) which gives the largest service time (i.e., transmission time or processing time) among all the servers over the connection. The interval of receipt of information (I) frames at the receiver to that of the departure of corresponding I-frames at the bottleneck server is approximated. This approximation enables an analytical throughput expression to be derived by observing the bottleneck server only. Compared with simulation results, analytical results obtained are in fairly good agreement if I-frames are discarded at the bridges located between the bottleneck server and the receiver. However, they are relatively overestimated if I-frames are discarded at the bridges located between the transmitter and the bottleneck server. It is shown also that the optimum window size is obtained as the smallest integer not less than the minimum acknowledgement delay over the service time of the bottleneck server. [ABSTRACT FROM AUTHOR]

We present an approach to keyhole plan recognition which uses a dynamic belief (Bayesian) network to represent features of the domain that are needed to identify users' plans and goals. The application domain is a Multi-User Dungeon adventure game with thousands of possible actions and locations. We propose several network structures which represent the relations in the domain to varying extents, and compare their predictive power for predicting a user's current goal, next action and next location. The conditional probability distributions for each network are learned during a training phase, which dynamically builds these probabilities from observations of user behaviour. This approach allows the use of incomplete, sparse and noisy data during both training and testing. We then apply simple abstraction and learning techniques in order to speed up the performance of the most promising dynamic belief networks without a significant change in the accuracy of goal predictions. Our experimental results in the application domain show a high degree of predictive accuracy. This indicates that dynamic belief networks in general show promise for predicting a variety of behaviours in domains which have similar features to those of our domain, while reduced models, obtained by means of learning and abstraction, show promise for efficient goal prediction in such domains. [ABSTRACT FROM AUTHOR]

A heat pipe thermosyphon radiator for use in domestic and industrialheating applications is presented. A test cell for the radiator is described and various experimental tests have been performed to determine the feasibility and performance of a heat pipe thermosyphon radiator. The thermosyphon radiator has been tested with freon 11, acetone, methanol and water as working fluids, and was compared with a conventional radiator. Best performance was obtained using methanol and acetone, and compares well with the conventional radiator. In addition,with these working fluids the thermosyphon radiator, by design, has desirable isothermal surfaces. The worst performance was with water, where local hot and cold spots formed on the radiator surface and theperformance was poor. A natural convection/radiation model is presented for the thermosyphon radiator, and good agreement between measured and calculated heat transfer is obtained. The model reveals that typically 60% of the heat is transferred by natural convection and the remaining 40% by radiation. Advantages and further development of thethermosyphon radiator are discussed. [ABSTRACT FROM AUTHOR]