最新刊期
卷 31 ， 期 11 ， 2003
- 摘要：An energy transfer photochemical model for the abatement of total organic carbon(TOC)in high purity water using 185nm Ultraviolet(UV)irradiations is proposed.The dependence of 185nm UV irradiation energy on the water flow rates,TOC concentrations and size of irradiation cell has been established.The models of selection of 185nm UV source and calculation in engineering design have been solved.The theoretical calculation agrees with experiments,which proves the model to be correct.The TOC concentrations in high purity water were decreased from 4200μg/L to 0.3μg/L,which is the lowest concentration of TOC.关键词：ULSI;total organic carbon;185nm UV;photochemistry2|2423|4更新时间：2025-07-16
- 摘要：Highly c-axis oriented ZnO thin films were deposited on single crystal Si(111)substrates by pulsed laser deposition(PLD).The photoconductive UV detectors based on ZnO thin films,being an MSM structure with interdigital(IDT)configuration,were fabricated by the desquamation photoetching method.The Al film-electrodes were deposited by planar magnetron sputtering.Results showed that the alloying temperature should be lower than 600℃.The I-V characteristic and the UV photoresponsivity of the detector were also investigated,indicating a good ohmic behavior between Al and ZnO thin film,a resistance about 100KΩ for the detector,and a photoresponsivity of 0.5A/W under ultraviolet illumination in ultraviolet region.关键词：ZnO thin films;photoconductive UV detector;ohmic contact;photoresponsivity2|1463|19更新时间：2025-07-16
- 摘要：The shallow parsing theory is applied to partition Chinese sentence parsing into three procedures:TAG,CHUNK,BUILD and CHECK.To resolve the problem of lacking feature types for available probabilistic models and make the best of useful information for parsing in context,we present probabilistic model based on maximum entropy to evaluate the probability of each action in the parsing procedures.In this model,any useful information for parsing in a context could be an actual feature; the features and training events are defined; the strategy of feature selection and the algorithm of parameter estimation based on Generalized Iterative Scaling(GIS)are given; The final result of parsing is the parse tree with the largest probability searched with Breadth-first search(BFS).The model is experimentally proved satisfying in both parsing efficiency and precision.关键词：natural language processing;maximum entropy models;chunk;sentence parsing;BFS2|1125|9更新时间：2025-07-16
- 摘要：This paper focuses on optimized design of Multi-Granularity Optical Cross-Connect(MG-OXC)node base-on two-stage(waveband and wavelength)multiplexing scheme and dynamic algorithm(including routing,wavelength assignment and traffic grouping)for Multi-Granularity Optical Networks(MG-ON),under dynamic traffic conditions.The performance of our MG-ON scenario is evaluated with numerical experiments under NSFNET and ARPANET topology,compared with OXC-based Wavelength Routed Optical Networks(WRON).The results show that the performance of MG-ON can be as good as WRON with proper design.关键词：MG-ON;MG-OXC;waveband;routing;traffic grouping2|1021|1更新时间：2025-07-16
- 摘要：Moment-matching is a widely used technique in analysis,design,and fast evaluation of signal transmission performance of interconnects in today's deep submicrometer VLSI design.The construction of exact moment-matching models for distributed RLC transmission lines involves a tedious and complicated procedure using previous methods.This paper provides a simple approach to derive such models based upon observations on the Maclaurin expansion of the ABCD matrix of the transmission line.In addition,a new method is proposed for the interconnects delay estimation,which can be used not only to the common second order model,but also to the third order,and even higher-order models.关键词：interconnects;high-speed circuits;delay estimation;signal integrity2|1334|3更新时间：2025-07-16
- 摘要：A probe-hole Field Emission Microscope (FEM) features the capability of measuring the respective dependence of local and total field emission currents on applied voltage.A FEM equipped with a probe-hole,which could be submitted to two-dimensional motion,was employed to acquire curves of field emission current versus applied voltage of single-walled carbon nanotubes (SWCNTs).The field emission currents were acquired from different regions and different adsorption states.Furthermore,the influence of heat treatment on current-voltage behaviors of the SWCNTs was also studied.关键词：field emission;field-emission microscope;single-walled carbon nanotubes2|755|0更新时间：2025-07-16
- 摘要：The performance of optical packet switching employing partially shared buffering (PSB) and shared wavelength converter (SWC) for self-similar traffics are studied.The effects of output buffers,the PSBs and SWC on the packet loss probability and delay are analyzed with consideration on the issues,such as dimension of switching matrix,buffering size,etc.The simulation results show that optical packet switching nodes with PSB and SWC are of good performance.The scheme of SWC can obviously reduce the number of wavelength converters in comparison with the scheme employing wavelength converters at each input wavelength path.For fixed depth,grouping PSB into several subgroups can improve the performance of optical packet switching nodes.关键词：optical packet switching;partially shared buffering;shared wavelength converter;IP over WDM;optical internet2|805|0更新时间：2025-07-16
- 摘要：This paper describes the design of a multi-channel high speed HDLC data processor which can process 128 logic channel HDLC data simultaneously.Its logic function and communication protocol coherence have been verified successfully by real-time operation system——vxWorks through FPGA.In the system,this multi-channel HDLC processor connects with 8 E1 physical links,and all 128 logic channel data separated from 256 timeslots of 8 E1 frames are processed by this single HDLC processor using time multiplex technology.Compared with other communication chips of this type,the above circuit structure takes more advantages in chip resources' taking up and channel management.关键词：HDLC;communication protocol;time division multiplexing;FPGA4|1104|2更新时间：2025-07-16
- 摘要：The existing teleconsultation systems generally need special networks or devices,which cause these systems to be expensive and limited.To propose a low-cost,high-efficiency and wide-adaptability remote-consultation system,we developed Teleconsult based on Visual C++ and COM.Well built on a PC/Windows platform and fully supporting H.323,Teleconsult is suitable for adoption in a wide range of TCP/IP networks.It provides a powerful teleconsultation environment with video/audio communication,text/image synchronous operation,etc.Specially,a set of image-processing tools is provided in the system.Teleconsult is a distributed multimedia system based on CSCW and is extensible on system functions.关键词：teleconsultation;CSCW;Distributed multimedia;H.323;image processing2|1037|0更新时间：2025-07-16
- 摘要：This paper studies the impact of congestion on the stability of a multicast(one-to-many)tree in the context of cumulative layered multicast congestion control mechanism.A stability factor is defined to evaluate and quantify this impact.For obtaining the general expression of the stability factor,a simple statistical model is developed.Simulation results shows that even in the case of lower link-marking probability,the stability of multicast tree is significantly more sensitive to network congestion when dependency between different links becomes smaller,indicating that more links will leave the tree when congestion occurs.关键词：layered multicast;congestion control;stability;TCP-friendly2|802|0更新时间：2025-07-16
- 摘要：A scalable admission-control method based on multiple-prior probing,aiming at the limitation of the traditional one-prior probing admission-control,is proposed to provide multiple-prior end-to-end QoS for individual flows according to their different QoS requirements and principle.The implementation of this method is explained in detail.To diminish the influence of probing collision on the performance of the proposed admission-control,a method of setting the alterable maximal number of the competing probing flows in the router is put forward so as to increase the resource utilization and ensure a high access success ratio.At last,the simulation in NS validates the advantage of the proposed admission-control method.关键词：multiple-prior probing;Quality of Service;admission control;probing collision2|626|0更新时间：2025-07-16
- 摘要：Based on power-flow-method,an effective approach for analyzing the electric property of PT(Piezoelectric Transformer)has been proposed in this paper.The main contributions are as the follows:(1).The formulas for calculating the optimal load,voltage's gain,efficiency,the output power of PT and so on have been derived;(2).According to these formulas,the procedure of finding out the electrical properties of PT has been put forward and the two new concepts,optimal load resistance and output matching network,have been introduced;(3).A few of simulated and exiperimental results have been given out to verify the conculsion.This approach is a very useful tool for analyzing the electric property of PT.关键词：piezoelectric transformer;electric property;matching network;optimal load2|766|1更新时间：2025-07-16
- 摘要：It is not desired that private key of mobile code owner will be revealed when it signs in other site.An algorithm on mobile code anonymity signature based on elliptic curve is given.Based on the algorithm,mobile code owner can use elliptic curve to create an authentication vector and a temporary key pair for mobile code according to its identification information,and implement anonymity signature and unrepudiation through them.In addition,the algorithm has features of high efficiency,secrecy and unforgery,and is able to be widely used to mobile computation.关键词：mobile computation;elliptic curve;anonymity signature2|759|0更新时间：2025-07-16
- 摘要：Location management,which consists of location update and location query,is a challenging topic in mobile communication.The basic location management scheme of personal communications services (PCS's) networks requires that location update be initiated whenever a mobile crosses the boundary of location areas.Obviously,this scheme is likely to waste the system resources due to the locality of mobiles' roaming.Therefore,reducing the cost of location management has become a hotspot of mobile communication.A location management schema with ring search (Ring Schema for short) was conceived,where no location update is needed.Additionally,a formula of the layer number of the location areas queried by Ring Schema was derived.According to this formula,the cost of Ring Scheme,on certain conditions,is less than both the cost of the basic scheme and that of the basic pointer forwarding schema.关键词：cellular networks;mobility management;location management2|1004|6更新时间：2025-07-16
- 摘要：Up to now all the known proxy digital signature schemes are based on discrete logarithmic problems or big number factorization problems.In this paper,we showed how to apply the idea of proxy digital signature scheme to elliptic curve digital signature algorithms by presenting a new proxy digital signature scheme based on elliptic curve discrete algorithmic problems.Furthermore,we also analyzed the new scheme's computation complexity and security problem.In the security analysis,we presented two hard problems over elliptic curves as well.The new scheme,which is an extension of elliptic curve cryptosystems,is beneficial for the construction of cryptographic schemes for solving some security problems.关键词：digital signature;proxy digital signature;discrete logarithmic problems;elliptic curve discrete logarithmic problems;elliptic curve digital signature algorithm2|1557|10更新时间：2025-07-16
- 摘要：The analysis method applied in the disk flexural vibration actuator was adapted properly and then used to deduce the equivalent circuit model of disk flexual vibration mode piezoelectric transformers.The equivalent circuit model is verified by the experimental results.Besides this,the theoretic analysis and experimental result also indicate that this new kind of components can prevent the destruction,decrease the permittivity loss and improve the efficiency in some degree.关键词：piezoelectric transformer;flexual vibration;equivalent circuit2|1204|3更新时间：2025-07-16
- 摘要：A novel VLSI architecture of hierarchical data path,based on VLIW core,is presented.Specific microcode structure is employed to exploit high speed and reconfigurable data path model that can efficiently improve the flexibility in system extending.It is also particularly convenient for high performance media processor array implementation.The design was implemented with VHDL and passed system simulation.The maximum data throughput will reach 1.28Gbit/s at 100 MHz system clock.关键词：high speed data path;VLIW;microcode;reconfigurable;VLSI design2|1049|0更新时间：2025-07-16
- 摘要：The switching time calculation method of the electrostatic driven MOEMS optical switch with torsion beam structure was presented,and the formula of the switching time was given.We gave the switching time for different structures.Finally optimization structure parameters are given,the electrostatic driving voltage is about 10V and the switching time is 1~2ms.关键词：MOEMS;torsion beam;slant low electrode;electrostatic driving;switching time2|850|2更新时间：2025-07-16
- 摘要：Discrete Wavelet Transform(DWT) has become very popular as the basis of many recent image processing and compression techniques and has been adopted by new image compression standard,i.e.,JPEG2000.The conventional convolution based DWT is computationally intensive.Such drawbacks can be overcome by using the lifting based scheme for the DWT.We presented a novel hardware structure for lifting based wavelet transform in JPEG2000.The hardware structure improves memory/speed tradeoff.Its computation speed is high and memory requirement is low.The complexity of datapath is reduced and the efficency of the system is improved by implementing the function of edge extension outside of data path.In the datapath design,we used pipeline technique to further improve the efficiency of the design.关键词：wavelet transform;lifting scheme;signal extension;pipeline;systemC2|1063|1更新时间：2025-07-16
- 摘要：When considering one-to-many or many-to-many transfer methods,people used to assume that only flooding,IP multicasting and multiple unicasting (point-to-point) are available. This article brings a new transmission approach:hybrid IP multicast.Based on a detailed analysis of these data transfer methods,we present an allocation strategy,which outperforms its counterparts.关键词：large scale distributed simulation;IP Multicast;multicast group allocation;hybrid IP multicast2|750|0更新时间：2025-07-16
- 摘要：It is an effective method to use diversity reception in Rayleigh channel.The best performance can be obtained when the diversity signals are independent of each other.The correlation between those signals deteriorates the bit-error performance.There is only an analysis for dual diversity in existing literatures.A theoretic analysis on bit-error performance is given when the diversity branches are more than two and correlative with each other.Especially,in the case of the non-uniform correlation between the diversity branches in practical application,the bit-error performance is analyzed and calculated,and the simulation is completed by use of a computer.Finally,some calculated results are given and plotted into curves for several kinds of typical cases.关键词：Rayleigh fading;multi-diversity reception;non-uniform correlative;bit-error performance2|1079|0更新时间：2025-07-16
- 摘要：Bayesian network is becoming more remarkable in AI research fields,which plays important role in modern expert system,diagnoses system and decision system.Bayesian network works on three points as below:knowledge representation,learning and inference.Prababilistic methods are its mathematical fundamental which helps learning distribution from data and leads Bayesian theory to real application.This paper introduces various common methods in probability data learning and make comparison among them under various application background.The methods based on classical statistics have a matured theory and a set of simple and direct calculation.But they reply heavily on sample data,which apply only those information from sample data with expert knowledge left aside.Bayesian Network combines information of expert knowledge and sample data together.It can give more accurate learning result and rely less on sample data.Parameter learning is main part of learning Bayesian Network models,and it's the basis of Bayesian Network learning.关键词：bayesian networks;conditional probability;parameter distribution2|1414|2更新时间：2025-07-16
- 摘要：For a large database,an efficient algorithm for mining association rules should try to reduce the number of the database passes and control the size of necessary memory.Temporal constraints can help us to get higher efficiency in data mining.This paper first defines temporal interval operators,and uses them to filter the database and merge temporal intervals for mining.Then,it gives a new effective algorithm called TISS-DM for mining temporal association rules.Finally,the performance of this algorithm is discussed.关键词：data mining;association rule;temporal interval;frequent itemsequence2|1184|2更新时间：2025-07-16
- 摘要：The provision of QoS in IEEE 802.11 Wireless LANs has recently become a research focus.Based on the previously proposed mechanism,a new self-adaptive algorithm with QoS guarantee on IEEE 802.11 wireless LAN is proposed.This new algorithm tunes the initial contention window of different priority stations dynamically to decrease the unnecessary collisions and achieves the optimal resource utilization.High priority stations and low priority stations are assigned different self-adaptive parameters to guarantee the QoS property of high priority stations.Numerous simulation results have been shown about the performance of the new mechanism.关键词：DCF;wireless LAN;QoS2|734|0更新时间：2025-07-16
- 摘要：By the aid of pluggable module,a security prototype is designed in the active network,which facilitates the security in the aspects of encryption,digital signature,authorization,authentication and revocation.The encryption and digital signature ensure the integrity and confidentiality to the active code.The decode-binding realizes the expansion capacity of the encryption methods in the system.By means of the certificate-checking method,the whole system designs a certificate center that issues X.509 certificate and manages the certificate through light directory access protocol (LDAP).With the active capability adapted to describe any authorization policy,the system can either choose the permitted policy or change the policy according to the requirements of the users .The revocation designed for the active network ensures the validity in the operation of the active code.In the meantime,with the trace records in the database,the revocation can realize the security alarm in the whole system.关键词：decoding binding;active code;access privilege control;pluggable module;active capability2|1188|2更新时间：2025-07-16
- 摘要：Network traffic prediction is important for network control and allocation.This paper presents a new method.The energy function of threshold value u to be constructed by the method of variance analysis for high-speed network traffic,presents bases for selecting threshold value.At last,according to threshold crossing theory,we examine the validity of the solution through calculating the crossing intensity.关键词：network traffic;threshold crossing problem;threshold value;crossing intensity2|882|0更新时间：2025-07-16
- 摘要：Robust Reference Watermarking(RRW)is a digital watermarking algorithm of still images based on the concept of multiresolution wavelet fusion.The concept of"Key points"is applied to watermarking in order to improve the robustness of RRW.Normal RRW uses only a constant Q to quantize wavelet coefficient.In the quantization process of improved method,if the watermark point is key point,then use larger quantizing parameter Q to quantize wavelet coefficient,else use smaller Q.When detecting watermark,key points'weight value are 1,and others'are constant not smaller than 0 and not larger than 1.Analysis is provided to compute the probability of false positive and false negative results.Experimental results show the performance of our method is better than the original RRW method and demonstrate its potential for the robust watermarking of photographic imagery.关键词：digital watermark;robust reference watermarking;key point4|916|0更新时间：2025-07-16
- 摘要：An unsupervised clustering-based intrusion detection algorithm is discussed.The basic idea of the algorithm is to produce the cluster by comparing the distances of unlabeled training data sets.With the classified data instances,anomaly data clusters can be easily identified by normal cluster ratio.And then the identified cluster can be used in real data detection.The benefit of the algorithm is that it needn't labeled training data sets.Using the data sets of KDD99,the experiment result shows that this approach can detect unknown intrusions efficiently in the real network connections.关键词：intrusion detection;data mining;unsupervised clustering;unlabeled data2|2884|29更新时间：2025-07-16
- 摘要：Inspired by the fractal pattern of mammalian digestive and circulatory system,a magical design of fractal branching channel heat sinks for cooling of electronic chips is studied.Based on the fractal branching net constructing,the heat transfer and pressure drop characteristics of fluid flow in fractal microchannel net are investigated.Furthermore,the fractal tree-like microchannel heat sinks are fabricated by multiplex inductively coupled plasma etching equipment in silicon wafer.The theoretical calculation and heat transfer experiments show that the fractal channel net has a higher heat transfer rate compared with the parallel channels having the same heat transfer condition and Nusselt number,the required pumping power for fractal channel net is decreased compared with parallel channels having the same velocity and heat transfer rate.Specially,the fractal channel net with larger dimensions can achieve higher heat transfer rate and lower pumping power on the same analyzed conditions.关键词：microchannel;net;fractal;heat transfer;heat sinks2|1674|3更新时间：2025-07-16
- 摘要：With the explosive growing of IP Data traffic,the carrier network is put forward to optical networks based on WDM technologies.And,accordingly several techniques have been proposed to improve the performance of the optical network,especially the control plane technology.Routing and Wavelength assignment (RWA) is one of the very important problems in WDM optical transmission network.Based on the conventional method named first fit (FF),a novel and heuristic algorithm called joint first fit (JFF) schemes is proposed for dynamic wavelength assignment in optical control plane of WDM network.Simulation results show that blocking probability can be significantly reduced and wavelength resource can be more efficiently used compared with First-Fit (FF) algorithm.关键词：WDM optical network;RWA;dynamic wavelength assignment2|1131|4更新时间：2025-07-16
- 摘要：The development and application of Mobile IN system in China is reviewed.The latest evolution of Mobile IN standards is introduced.Then the integration of IN and mobile network in the third generation mobile system is analyzed.After the deficiencies of IN deployment are concluded,the study status and trends of mobile IN technology are surveyed,together with some key techniques.Several hot mobile IN services in the near future are listed,followed by some advise on further development in our country.关键词：intelligent network(IN);mobile IN;third generation(3G)mobile communication system5|1406|5更新时间：2025-07-16
- 摘要：Fractionally spaced equalization (FSE) can reduce sensitivity to timing synchronization errors.The constant modulus algorithm (CMA) for FSE can be improved by modifying its error function and a modified constant modulus algorithm (MCMA) for blind fractionally spaced equalization is proposed.The MCMA is compared with the conventional constant modulus algorithm (CMA) for FSE for 8PSK signals.It is shown that the MCMA is superior and more robust in noise environments under freqency selective channels.Simulation results demonstrate the MCMA can effectively improve channel equlizations by increasing convergence rate and decreasing steady-state mean square error and intersymbol interference (ISI).关键词：fractionally spaced equalization (FSE);blind Channel equalization;constant modulus algorithm (CMA);modified constant modulus algorithm (MCMA);intersymbol interference (ISI)2|1027|2更新时间：2025-07-16
- 摘要：Pressure sensor for high temperature is very useful for various area applications.Some special materials such as SIC,SOI can be used to manufacture high temperature pressure sensor,but due to the difficult process or/and cost,they are not used widely.In this paper,a novel poly-silicon pressure sensor is designed,further more a CMOS fully depleted integrated circuit is used to change output signal into 0~+5V industrial signal.After simulation and process experiments,the optimized condition of poly-silicon diffusion concentration was found,and the temperature coefficient is reduced to nearly zero between -40℃~180℃.关键词：integration;CMOS;poly-silicon;pressure sensor2|1914|0更新时间：2025-07-16
- 摘要：The paper analyses the weakness of traditional speed-up techniques for image fractal compression firstly,and proposes a novel idea by using entropy to improve image fractal compress performance.A theorem is proved that the IFS cannot change the image blocks' entropy values.Moreover,it gives a novel fractal compression method based on entropy and its extension.The simulation results illuminate that the new method can improve the PSNR,compress ratio and compress time cost.关键词：fractal compress;iterated function system;entropy2|1195|6更新时间：2025-07-16
- 摘要：Active Queue Management is an active research area.Its main objective is to provide low delay and low loss service in packet-switched network.RQ is a new random early detection algorithm.It can divide the seriousness of congestion into six levels according to the aggregate packet arrival rate and the average queue length in the router.Each level has appropriate packet drop probability.The responsiveness and stability properties of RQ are superior to RED in favor of promptly reacting of rate-based dropping than queue-based.TCP and RQ are modeled as a closed loop feedback control system and the stability is analyzed.The performance of RQ was compared with RED by simulations.The results show that RQ can keep low queuing delay and low packet loss in wide variable load conditions.关键词：congestion control;active queue management;packet arrival rate;queue length2|880|3更新时间：2025-07-16
- 摘要：To prohibit privilege abuse,operating system must clearly know the necessary privileges needed by a program.The paper researched the key factors about the privileges needed by special applications,and brought forward a security framework.Based on user's knowledge about an application,this framework deduced the privileges the application needed by using professional knowledge about system architecture etc.,thus restricted the privilege abuse.Our framework balances accuracy and facility about privilege abuse,and is practical.关键词：information security;privilege abuse;untrusted application2|1256|1更新时间：2025-07-16
- 摘要：An irrelevant feature preprocess based on the minimal class difference is proposed.It computes the class distribution difference of features according to their distribution,then divides the features into three types.The new preprocess keeps the features including single-class features and multi-class features which make for classification,and filters the general features with little use for classification.The experimental results show that better performance can be obtained using the new algorithm than using those algorithms such as information gain,mutual information,and cross entropy.关键词：information gain;mutual information;naive Bayesian2|1499|3更新时间：2025-07-16
- 摘要：Layered space-time (LST) architecture is effective in achieving high data rate in wireless communication.Zero-Forcing (ZF) and Minimum Mean-Squared Error (MMSE) algorithms are two common detection algorithms for LST codes.However,both ZF and MMSE require the number of receive antennas to be no less than that of transmit antennas,thus greatly limits the application of LST codes in mobile communication.In this paper we introduce Maximum Likelihood (ML) detection algorithm for LST codes,which has no limit on the number of antennas,and compare the performance of the three detection algorithms for layered space-time codes over flat fading and Rayleigh fading channel.Their applicability is then pointed out respectively.关键词：layered space-time codes;zero-Forcing algorithm;minimum mean-squared error algorithm;maximum likelihood detection2|844|2更新时间：2025-07-16
- 摘要：This paper introduces the function and profile of SDP in Bluetooth at first.It focuses on the project of HCRP and offers a method to the design and realization in Bluetooth environment.关键词：server;client;HCRP;UUID;SDP2|837|0更新时间：2025-07-16
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