最新刊期
卷 30 ， 期 4 ， 2002
- 摘要：Phase encode-spreading optical code division multiplex access (OCDMA) communication system is one of the research focuses in recent years.We have established the system model of such OCDMA system basing on phase mask and analyzed its performance.The calculated result shows that longer code length and shorter initial optical pulse width will lead to better system performance.关键词：OCDM;spectral encode;phase mask2|898|0更新时间：2025-07-16
- 摘要：GPS(Generalized Processor Sharing) is one of fluid models for scheduling,and some algorithms,such as WFQ(Weighted Fair Queueing) and WF2Q(Worst-case Fair WFQ),etc.,are based on the simulation of GPS.This paper proves that WFQ,WF2Q,are not the packet-by-packet GPS.Therefore,these algorithms cannot guarantee the delay and services characteristics of P-GPS.A new Packet Fair Scheduler based on the exact simulation of GPS is proposed.关键词：scheduling algorithm;GPS;weighted fair queuing;rate-proportional server2|970|2更新时间：2025-07-16
- 摘要：Mobile agent technique is a new kind of network technology and the electronic commerce is one of the main applications of mobile agent.In this paper we propose an anonymous mobile agent scheme for Internet applications due to the higher anonymity request of users in electronic commerce.In our scheme,the validity of a mobile agent can be verified by servers without leaking the identity information of user.However,the identity of one whose agent makes a malicious attack to a server will be traced out by Agent Management Center.2|788|0更新时间：2025-07-16
- 摘要：Channel estimation is a key technique in the field of mobile communications.Especially,with the demand of next generation mobile communications,the channel estimation theory in the high data rate and high speed mobile environment will become a dominant technique in mobile communications.This paper presents a novel method named Channel Estimation by using Two Orthogonal Channels (CETOC) method applied to high data rate and high speed mobile communications.This method can effectively overcome influence resulted from fast fading by using the joint estimation of two independent orthogonal channels,so it is possible to use high-dimensional modulation in fast fading channel.关键词：high speed mobile environment;channel estimation by using two orthogonal channels;phase shift;multi-dimension modulation3|934|1更新时间：2025-07-16
- 摘要：A new secure Vickrey auction protocol is presented in this paper by using the bit commitment protocol,multi-party secure computation protocol and the ElGamal encryption scheme.With the advantages of anonymity,privacy,efficiency,the protocol also supports the optimal distribution of goods,Even when some bidder works together with the auctioneer,the protocol is still secure and valid.关键词：sealed bids;the second-price;bit commitment2|848|0更新时间：2025-07-16
- 摘要：By ADSL (Asymmetric Digital Subscriber Line) technology,high speed access INTERNET can be realized through twisted copper pair lines which are already used in PSTN (public switch telephone network) to connect telephone users.ADSL becomes a focused point in area of access network.The paper describes ADSL DSLAM (Digital Subscribe Loop Access Multiplexer) architectures and how to design and realize them.It analyses the transmission efficiency of these DSLAM and gets the result that the ADSL DSLAM with IP direct connection is more efficient.It discusses in detail the realization of ADSL DSLAM with IP direct connection architecture.The solutions to some key problems are given.关键词：ADSL;DSLAM;broadband network;access network2|1120|0更新时间：2025-07-16
- 摘要：The DFT based OFDM has currently been mostly focused in the area of wireless communications.To attain to a high level QOS and reduce ISI,cyclic prefixes are inserted between DFT-OFDM symbols,which decrease the efficiency of spectrum.To improve spectrum efficiency,a complex wavelet packet transform based OFDM (CWP-OFDM) is proposed in this paper and used to compare with the DFT-OFDM under the same conditions.Simulation results show that,over GSM TU50 channels,when there is a much higher efficiency in using wireless spectrum,CWP-OFDM performs the same as or better than DFT-OFDM.关键词：complex wavelet packet;DFT-OFDM;CWP-OFDM;Doppler frequency shift;channel estimation2|938|0更新时间：2025-07-16
- 摘要：In order to adapt to the era of information、network and intelligent of modern industrials,a practical and new designing method of PLC hierarchical control system is proposed in this paper.The initial practice shows that this method is feasible and has a consulting value with the technical reform.关键词：programmable controller(PLC);PLC network;hierarchical intelligent control2|1794|1更新时间：2025-07-16
- 摘要：Recent initiatives to add mobility to the Internet are being considered by emerging mobile service providers as possible candidate solutions for the delivery of IP(Internet protocol) data to mobile users.Mobile IP is thus a solution for mobility on the global Internet which is simple,scalable,but there are some problems necessary to be solved.Route optimization techniques make extensions to the base Mobile IP protocol to improve the network performance.In this paper,both schemes have been analyzed and simulated.The results show that the performances in terms of throughput rate as well as end to end delay largely depend on the offered traffic pattern.Furthermore,both protocols can't support frequent handoff in future micro cell environment.关键词：mobile IP;route optimization;mobile computing2|1241|6更新时间：2025-07-16
- 摘要：In this paper,an alternate routing algorithm is proposed for the problem of routing and assignment of wavelength in Wavelength Division Multiplexing (WDM) optical transport network.It can more accurately model the state of the whole network after the establishment of new calls than other alternate algorithms proposed before.The route-wavelength pair which has the least influence on the state of the whole network is chosen to accommodate the coming call.The algorithm performs better than other alternate routing algorithms in most cases we studied.Fairness is improved significantly too.关键词：WDM optical transport network;alternate routing;routing and assignment of wavelength2|933|1更新时间：2025-07-16
- 摘要：In the wideband code division multiple access (WCDMA) system,fast transmit power control (TPC) should overcome the pathloss caused by fast multipath fading.However,the conventional fixed step size transmit power control (FS-TPC) does not compensate the fading well due to the complexity of fast fading in Rayleigh channel.We propose and evaluate a single-bit adaptive step-size transmit power control (AS-TPC) scheme which can be applied in WCDMA.The new scheme divides the power control process into Markov states according to the received TPC command in "history".On the basis of analysis of the step-size of the channel fading,it chooses step-size according to the largest probability density of step-size of the multipath Rayleigh fading channel with respect to the period of the transmit power control.Each TPC step size is corresponding to a channel Markov states.Considering the power circuit's minimum resolving is about 0.5dB,we can decide the step size set.In this paper,the relationship between the Markov state and the TPC step-size is made out by computer simulation.The transmitter decides increasing or decreasing the transmit power according to the received TPC command.However,the changing quantity is chosen according to the current TPC command and the historical TPC commands.关键词：transmit power control;WCDMA;mobile radio;Markov process2|968|0更新时间：2025-07-16
- 摘要：According to the requirements of the technique in mobile computing network,an efficient protocol for mutual authentication and electronic payment for mobile computing network is proposed.The paper also demonstrates how a micropayment scheme can be integrated into the authentication protocol.The protocols provide security services required by regular authentication and payment protocols and are efficient in consideration of the storage requirement and computation overheads on subscribers.They protect subscribers from incorrect service charges and provide service providers legal evidences to collect bills that are denied.By using public key infrastructure,they can be used as authentication and payment protocol in future mobile systems.关键词：mobile computing network;authentication;micropayment;public key infrastructure2|920|7更新时间：2025-07-16
- 摘要：Parallel interference cancellators have been used gradually because of their better performance and lower complexity,for example,in 3G demo systems of Japan.The approaches of regenerating interference and structures of parallel interference cancellators must be adjusted for the sake of small spread factors of 3G systems.Aiming at the question of interference regeneration of multistage non-linear parallel interference cancellators with small spread factors for frequency selective Rayleigh fading CDMA systems,we propose a concept of attenuation factors,reasons and a novel scheme of multistage non-linear parallel interference cancellation (PIC) based on attenuation factors.Moreover,we analyze in detail the performance of multistage non-linear PIC with small spread factors,which benefits from attenuation factors.And simulation results show that to what extent the performance of the novel multistage non-linear PIC based on attenuation factors can be improved.关键词：PIC;attenuation factor;Rayleigh fading2|799|0更新时间：2025-07-16
- 摘要：Congestion control plays an important role in the effective and stable operation of ATM networks.This paper proposes an approach to design a rate-based flow control mechanism in order to regulate the Available Bit Rate (ABR) traffic and effectively control congestion of the networks.The goal is to share the available link capacity fairly among many competitive users to maintain queue length of a bottleneck node at a desired level.The mechanism uses a Deadbeat-Response (DR) controller and has a simple structure.Many simulations show that the mechanism is fair and has the advantages of fast convergence,no oscillation,and high link bandwidth utilization.关键词：ATM networks;congestion control;flow control;deadbeat-response control2|1245|4更新时间：2025-07-16
- 摘要：In this paper,an adaptive allocation algorithm for multiuser Orthogonal Frequency Division Multiplexing (OFDM) system over multipath frequency selective fading channels is proposed.According to the estimation of instantaneous channel characteristics,the adaptive allocation algorithm assigns the subchannels and bits for multiuser in the system to minimize the total transmission power for a given bit error rate (BER).Firstly,we apply the conception of time division multiplexing to the system to propose an optimum subchannel and bit rate allocation algorithm for multiuser,which results a low bound of the transmission power in the system.Then,a suboptimum adaptive allocation algorithm is proposed.The numerical simulation shows that the transmission power determined by the suboptimum adaptive allocation algorithm is 1dB bigger than that of the low bound;3-4dB less than that in equal bit allocation (EBA) and 6-8dB less than that in static subchannel allocation (SSA).关键词：OFDM;channel allocation;adaptive modulation2|1063|1更新时间：2025-07-16
- 摘要：Based on the properties of DPSK (differential phase-shift keying) signal in Rayleigh flat-fading channels,we propose a novel decision aided algorithm for iterative DPSK signal demodulation/decoding.It utilizes decision feedback bits to estimate the channel coefficients and calculate the likelihood ratio of information bits.Compared with conventional iterative DPSK signal demodulation/decoding based on the BCJR (Bahl-Cocke-Jelinek-Raviv) algorithm,the new algorithm results in considerably low decoding cost yet can achieve nearly the same performance.关键词：decision;decoding algorithm;decoding cost;Turbo DPSK2|1100|0更新时间：2025-07-16
- 摘要：In this paper,a kind of optimization restoration routing algorithm based on the Genetic Algorithm is presented for WDM optical transport network.For multi-constraints cases,it can process the problem of optimal restoration-route search for different purpose in the cases of various failure conditions.Through the numerical results of practical networks,the practicability has been proved.关键词：WDM optical network;mesh network;network survivability;routing restoration;genetic algorithm2|1030|2更新时间：2025-07-16
- 摘要：This paper presents a perfect zero-knowledge proof system for a decision problem which is computationally equivalent to the Discrete Root Problem,and its zero-knowledge property does not rely on any assumptions.Thus we provide additional evidence to the belief that perfect zero-knowledge proof systems exist in a non-trivial manner (i.e.,for language not in BPP).关键词：interactive proofs;perfect zero-knowledge;discrete root;promise problem2|988|0更新时间：2025-07-16
- 摘要：We build a bridge between the wavelet and pulse shaping and propose an ISI-free pulse shaping theory frame based on wavelet.Three optimal baseband pulse shaping methods over time-discrete multipath Rayleigh fading channel based on scaling function,wavelet function and wavelet packet function are presented and strictly verified.The simulation by computer shows that it has better performance than conventional pulse shaping,and acts as a spread code.关键词：wavelet;pulse shaping;multi-path channel2|1085|0更新时间：2025-07-16
- 摘要：A kind of admissible support vector kernel called scaling kernels are presented in this paper.In fact,scaling kernels are the multi-dimensional scaling function with translation vectors and they are a set of complete bases in the sub-space of the square and integrable space.Hence,the goal of scaling kernel function support vector machines is to find the optimal scaling coefficients in a scaling space.In terms of theory,scaling kernel function SVMs can approximate any objective function in some space by any precision.The results obtained by our simulations show the feasibility and validity of scaling kernels.关键词：support vector machine;support vector kernel;scaling kernel;gaussian kernel2|1288|14更新时间：2025-07-16
- 摘要：Based on the known principle of fixed points in mathematical analysis,a sufficient convergence condition of erasure decoding algorithm for erasure codes is shown.Moreover,it is pointed out that this convergence condition is weaker than the convergence condition available.Finally,some upper bounds on the maximum tolerable loss fraction δ for which their decoding is successful are shown given a degree distribution pair.关键词：LDPC code;low-density erasure code;erasure decoding algorithm;stability condition2|1002|5更新时间：2025-07-16
- 摘要：This paper presents a new class of complete security protocol——advantage degeneration protocol.Advantage degeneration protocol and former advantage distillation protocol have different functions:one means that the mutual information of communication partners is distilled firstly,another that the information of enemy is degenerated firstly.The paper discusses conditions for efficient protocol,and presents a mixed protocol which has both advantage distillation and advantage degeneration functions.关键词：complete security;key agreement;advantage distillation;privacy amplification2|781|0更新时间：2025-07-16
- 摘要：In secure communications,it is difficult to solve some existing problems of conventional synchronization between two continuous-flow chaotic systems.Therefore,in this paper the theorems on synchronization based on digital-flow chaos in secure communications are presented and a scheme of secure speech communication are presented and realized.In the scheme a new synchronic method——cycles and interval pulse drive is developed and realized.Experimental results show it is feasible.关键词：digital-flow chaos synchronization;cycles and interval pulses drive;synchronization noise2|976|6更新时间：2025-07-16
- 摘要：A new multiple secrets sharing scheme,based on the intractability of the discrete logarithm (DL) and the RSA encryption algorithm is presented,in which the participants' shadows remain secret and can be reused,even if all subshadows are made public.Meanwhile,by using a zero-knowledge proof protocol,the validity verification of shadow and subshadow is also provided to prevent both dealer cheating and other participant cheating,and any freely given secrets without pre-computation by dealer can be reconstructed.The scheme can be applied to many areas such as conference key distribution,secure multi-part-computation,threshold signature etc.关键词：multi-secret sharing;threshold scheme;discrete logarithm;RSA;zero-knowledge proof2|1284|22更新时间：2025-07-16
- 摘要：In this paper a real-time Parcel Post Checking Speech Recognition System is developed.This system can achieve the parcel post information checking and verification by means of a medium vocabulary speaker-independent continuous speech technology.Input speech can be Mandarin or Sichuan dialect.Vocabulary size is about 4500.By employing the advantages of the rejection model and speaker adaptation technology,the system's robustness is improved remarkably.The experiments show that the system has a very good performance.For mandarin voice input,the recognition accuracy of the top one candidate is 98.7%,and the recognition accuracy of the top three candidates is 99.9%; For Sichuan dialect one the recognition accuracy of the top one candidate is 95.9%,and the recognition accuracy of the top three candidates is 98.6%.关键词：speech recognition;confidence measure and rejection;speaker adaptation;information checking and verification2|954|1更新时间：2025-07-16
- 摘要：Edge extraction is an important stage to image understanding.To improve past methods for edge extraction,this paper presents an algorithm of accumulation of self-reinforcement of independent edges.First,use repetitive random searches to obtain various possible independent-edge trajectories in edge images.Then,self-reinforce and accumulate the search trajectories respectively.At last,extract the edges according to the results of the accumulation of self-reinforcement.Through lots of experiments and comparing with other techniques of edge extraction:relaxation algorithm and heuristic search algorithm,this method can extract edges effectively and suppress the noise significantly.2|688|0更新时间：2025-07-16
- 摘要：Transmission of wavelet-coded images over lossy packet networks presents an image reconstruction problem.A new image reconstruction algorithm called Wavelet Domain Interpolation for tree Reconstruction (WDIR) to conceal coefficients loss in Wavelet-Trees is developed.The reconstruction of the lost high-frequency coefficients is given by using mathematical morphological dilation operator based on the horizontal and vertical edge detection ability of 2-D wavelet transform.To maintain the sharpness of edges,we reconstruct the lost low-frequency coefficients under the direction of high-frequency coefficients.The algorithm performs well in performance simulations.关键词：image transmission;interpolation;error concealment;wavelet transform2|943|6更新时间：2025-07-16
- 摘要：For expanding the capacities of WDM(Wavelength Division Multiplexing) star networks free from the number of limited wavelengths,a scheme of reusing wavelengths two times is proposed in this paper.According to the scheme,not only the number of nodes can be increased two times,but also all the data wavelengths can be reused two times in the network and the throughput of the network is increased two times.Under the same number of nodes,the delay of network can be greatly lowered and the properties of the network can be efficiently improved.Besides,through the network structure proposed is simple,and the scheme can be easy implemented in practice.关键词：star network;WDM(wavelength division multiplexing);wavelength reuse;network capacities;gains2|669|0更新时间：2025-07-16
- 摘要：The mobile agent technologies and their applications in network management environment (NME) were discussed.The mobile agent applications developed in NME were classified via the function the mobile agent completed.The The background of the mobile agent applications in NME was analyzed.The problems existed in developing mobile agent applications in NME were pointed out.Some suggestions to develop mobile agent applications in NME were given.Related research works remaining to be resolved and future trend of mobile agent applications in NME were discussed.关键词：network management;mobile agent2|1656|8更新时间：2025-07-16
- 摘要：Blind signal processing is attractive in the community of signal processing.Blind source separation and Blind deconvolution are main components in blind signal processing and advances have been developed in recent years.We introduce the basic model of blind source separation and blind deconvolution,the mathematical principle of them,and the latest progresses in research.We then analyze the characteristic of typical algorithms and point out the future development.关键词：blind source separation;blind deconvolution;independent component analysis2|5102|31更新时间：2025-07-16
- 摘要：Formulas for updated rules of the belief propagation algorithm applied to low density parity check (LDPC) codes are systematically derived based on the tree and the finite state machine (FSM).The probability measure on the continuous message space is introduced to evaluate the evolution of message densities within iterative decoding rounds,and derivations of the output distributions of common binary symmetric channels and the message density evolution are given in detail.The parameterized estimation of the performance of the algorithm is also discussed.The analytic and calculable means can be used to make systematical analysis for the convergence of BP algorithms independent of channels,and can be of help in designing LDPC codes and analyzing quantization effects for the fast decoding on the purpose of practical applications of LDPC codes to real-time communication systems.关键词：measurement;belief propagation algorithm;iterative decoding;LDPC codes;Turbo codes2|1328|1更新时间：2025-07-16
- 摘要：TPC (Transmit power control) is one of the key techniques to maximize the capacity of CDMA(Code Division Multiple Access) system.Highly precise measurement of inner-loop SIR (instantaneous signal-to-average interference plus background noise ratio) is the foundation of highly precise fast closed-loop TPC in WCDMA (Wideband Code Division Multiple Access) system which is selected as one system for IMT-2000 (International Mobile Telecommunications-2000).This paper proposes a new measurement method of inner-loop SIR based on 3GPP (the third Generation Partnership Project) protocols,which is prone to modularization,and compares it with another method brought forward by Shunsuke in principle and performance.It has been proved that the new measurement method has the better performance by means of computer simulation.The performance of fast closed-loop TPC based on producing equal QoS (Quality of Service) for all users is also given.关键词：transmit power control;WCDMA;SIR;measurement method2|1179|0更新时间：2025-07-16
- 摘要：A method based on assisted-pilot and polynomial model is proposed for high speed mobile environment.Radio channel response at any time instant is estimated from the received pilots of two or more time slots,assuming that channel response can be modeled as a polynomial.For WCDMA (Wideband Code Division Multiple Access) uplink,the relation between the link performance and the mobile speed are studied by simulation.The optimal polynomial order and the optimal number of time slots are also investigated.Performance comparison between the proposed method and the WMSA (weighted multi-slot average) method is made from the simulation results.关键词：polynomial model;Signal reconstruction;wideband CDMA;channel estimation;RAKE receiver2|1224|5更新时间：2025-07-16
- 摘要：In this paper,One Dynamic Time-Slot Allocation(DTSA) solution is proposed to enable the simultaneous access of voice,FAX and data on DDN leased line.This solution can guarantee the QoS of these services and also improve the utilization of the bandwidth.A thorough analysis of this solution's performance and the comparison with VoIP are given in this paper.The performance of this system shows that this solution can provide better QoS.Its simplicity makes this scheme more attractive than VoIP scheme.关键词：dynamic time-slot allocation;VoIP;DDN;multi-service access;multiplexing2|955|1更新时间：2025-07-16
- 摘要：An improved adaptive zerotree based embedded image coding of wavelet coefficients is put forward.With the adaptive wavelet coefficients,more zerotrees are produced in this process,and the PSNR can be improved by 0.1~0.6dB at the same code stream.Furthermore,the code stream produced is embedded and able to support multirate image decoding.关键词：image coding;wavelet transforms;embedded zerotree wavelet;KLT;image compression2|862|0更新时间：2025-07-16
- 摘要：In this paper,a new mathematics model,3D matrix,is researched.Its application in color digital image compression coding,3-D wide discrete cosine transform (WDCT) compression coding,has been proposed.We also gave its calculate method,transform,inverse transform,performance and proof them.As we known,it is identity physics model unify reflect into that of colour image's three frame,possess same texture,same fringe and same gray change,the information of the each frame almost could reflect the source image except colour,the vision similitude are very strong.Human vision characteristic express that the relation of the each component is unlinely.It is clear that if we encode Y Cr Cb data separately,among each component potential relativity can be incapable of plenitude utilize colour image So we regard R,G,and B as a whole and make it into the single mathematics model,3D matrix,and transform it with3D WDCT.Different from other transform coding method,in which each component was compressed and encoded separately,it combined the intra and inter component compressions encoding together.Simulation results demonstrate good reconstruction image quality and high compression ratio of method.It use adult discrete cosine transform technology,and have good compatible for the moment universal JPEG and MPEG standard.关键词：3D-Matrix;color image;compression coding;WDCT2|1263|13更新时间：2025-07-16
- 摘要：Split spectrum processing has been proposed for ehnancement of flaw echo in ultrasonic testing of materials with large grains.The split spectrum technique is a method where one wideband ultrasonic pulse echo is filtered through a narrowband filter bank.However,the split spectrum processing algorithms are not robust since it is not clear how the technique use the filter outputs available.In this paper,a signal model of ultrasonic testing for large grained materials is developed.Using this model,the outcoming ultrasonic signal of a narrowband filter bank is obtained.Finally,some simulation resutls are illustrated.关键词：ultrasonic testing;large grained material;signal model;output properties of narrowband filter2|1033|2更新时间：2025-07-16
- 摘要：A neural network for solving systems of nonlinear equations is proposed in this paper.For an arbitrarily given initial point of systems of nonlinear equations,the network converges to a real solution stably.First,the stability,convergence and feasibility of the network are strictly proved.Then a simulation algorithm and its applications are provided.Finally,some numerical tests are given to show the effectiveness of the network.关键词：systems of nonlinear equations;neural network;energy function;stability2|3476|7更新时间：2025-07-16
- 摘要：The methods of identifying communication stations and their platforms using the rough set theory in the communication reconnaissance information fusion system are discussed,and some typical application examples are given and analyzed in detail.It gives out a beneficial reference to applying the rough set theory in data fusion.3|1358|6更新时间：2025-07-16
- 摘要：Filtering in polarization domain has been investigated with respect to the unknown and time-varying clutter or interference environment.An adaptive recursive-filtering algorithm is proposed.At first,the polarization coherence matrix is estimated by the independent secondary data.Then the polarization of antenna is optimized according to the polarization information.At last,the minimum complex volume is obtained.The recursive scheme makes it go fluently.The simulation experiments demonstrate its validity.The performance curve of stability approaches the optimum theoretically.The study curve reflects its transition property.关键词：polarization;adaptive;filtering2|1641|20更新时间：2025-07-16
- 摘要：By far,the research about limited-range wavelength converter is concentrated on FWM (SOA (Semiconductor Optical Amplifier) in Four-Wave Mixing) wavelength converter which can convert the input wavelength to longer or shorter output wavelength,or on wavelength converter which has wraprounds capability.In this paper,the network performance which is influenced by XGM( SOA(Semiconductor Optical Amplifier) in Cross-Gain Modulation) wavelength converter which can only convert input wavelength to shorter output wavelength is studied.The research result shows that although the performance of network with XGM wavelength converter approximates to the performance of network with FWM wavelength converter which has 10-20% converting range capability,the performance improvement is significant and is not far away from the performance with all-range wavelength converter.关键词：XGM wavelength converter;FWM wavelength converter;WDM;limited-range wavelength converter;blocking probability2|818|1更新时间：2025-07-16
- 摘要：After analyzing the dipole model of target,this paper points out that the magnetic dipole signal is a combination of two kinds of functions,and the target parameter is contained in the parameter of these functions.It develops the function construction method for breaking the combination of functions into independent parts,thus determines the target location and magnetic moment in a step by step way.Finally simulations results are presented.The paper goes on to explain the mathematical essence of the method of combined functions,thus the method can be further applied to a broader class of problems.关键词：magnetic dipole;positioning;function construction method;the non-linear least square method2|2599|17更新时间：2025-07-16
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