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1.
Qiao Jie Zhao Li Zou Cairong 《电子科学学刊(英文版)》2007,24(2):267-270
Acoustic echo cancellation based on sub-band filters has the characteristics of rapid con- vergence and small computational complexity. This letter analyses two different sub-band filters design methods which used in acoustic echo cancellation fields and compares them with each other. Fur- thermore, the sub-band filter construction have been optimized, which lead to the improvement of the computational efficiency. At the same time, this letter combines ear auditory feature with acoustic echo cancellation, thus improves the original algorithms by importing a new objective function creatively. At the last part, a simulation environment has been designed and a computer simulation has been carried out. The final results indicate that this method can meet the requirements of actual projects, and some improvements are demonstrated on performance and calculation quantity compared to original algo- rithms. 相似文献
2.
KADONO Yasuo 《中国电子科技》2004,2(3)
Many corporate senior managers have not been fully convinced of successful IT management over a period of decades. In order to clarify the mechanism of IT management in companies, we conducted the surveys on IT management in 2000 and 2002. Through the surveys and analyses, we found the causal structure in IT management, developed "IT Management Effectiveness" as a new measurement tool, published ranking lists of high scored companies, and analyzed characteristics of industry/sizes of respondents and so on. Based on the surveys and researches so far, we would suggest future works, such as comparison of Japanese companies with overseas companies, time series analyses. 相似文献
3.
The physical effects of the carrier distribution in the channel on the dynamical performance of a static induction thyristor (SITH) have been studied numerically and experimentally. The analytical expressions of the minority carrier distribution in the channel of the SITH were also derived and the space charge distribution control- ling mechanism on the current of the SITH under high level injection have been analyzed deeply. The relationships among the minority carrier distribution, potential distribution, I-V characteristics and transient performances of the SITH are revealed. 相似文献
4.
Hequan Wu 《中兴通讯技术(英文版)》2011,9(1):1-2
Tri-network convergence is becoming a hot topic as interest in 3G, the Internet of things, and cloud computing continues to grow. Most countries now place great emphasis on tri-network convergence and one after the other have prioritized it as a means of developing new strategic sectors. With the arrival of 2011, our magazine has the honor of inviting Mr. Hequan Wu, a telecommunications expert from the Chinese Academy of Engineering to deliver a speech on the characteristics and challenges of tri-network convergence in China. According to Mr. Wu, some developed countries have already achieved tri-network convergence and others are promoting it. China has its own characteristics in implementing tri-network convergence, and these characteristics are bringing new management modes and new challenges. Mr. Wu pointed out that new management modes were needed in the process of tri-network convergence in China, and the introduction of the integrated network broadcasting control platform would bring about new challenges to management modes. Adaption to the platform requires cooperation and innovation. Finally, Mr. Wu emphasized the key to the success of Chinese tri-network convergence was to develop new services and business models. 相似文献
5.
Incorporating electric vehicles into smart grid,vehicle-to-Grid(V2G) makes it feasible to charge for large-scale electric vehicles,and in turn support electric vehicles,as mobile and distributed storage units,to discharge to smart grid.In order to provide reliable and efficient services,the operator of V2 G networks needs to monitor realtime status of every plug-in electric vehicle(PEV) and then evaluate current electricity storage capability.Anonymity,aggregation and dynamic management are three basic but crucial characteristics of which the services of V2 G networks should be.However,few of existing authentication schemes for V2 G networks could satisfy them simultaneously.In this paper,we propose a secure and efficient authentication scheme with privacy-preserving for V2 G networks.The scheme makes the charging/discharging station authenticate PEVs anonymously and manage them dynamically.Moreover,the monitoring data collected by the charging/discharging station could be sent to a local aggregator(LAG)in batch mode.In particular,time overheads during verification stage are independent with the number of involved PEVs,and there is no need to update the membership certificate and key pair before PEV logs out. 相似文献
6.
Based on the I-V characteristics and the function of adjustable threshold voltage of a single electron transistor (SET), we design the basic ternary logic circuits, which have been simulated by SPICE and their power and transient characteristics have been extensively analyzed. The simulation results indicate that the proposed circuits exhibit a simpler structure, smaller signal delay and lower power. 相似文献
7.
In the past five years,all-inorganic metal halide perovskite(CsPbX3,X=Cl,Br,I)nanocrystals have been intensely studied due to their outstanding optical properties and facile synthesis,which endow them with potential optoelectronic applications.In order to optimize their physical and chemical properties,different strategies have been developed to realize the controllable synthesis of CsPbX3 nanocrystals.In this short review,we firstly present a comprehensive and detailed summary of existed synthesis strategies of CsPbX3 nanocrystals and their analogues.Then,we introduce the regulations of several reaction parameters and their effects on the morphologies of CsPbX3 nanocrystals.At the same time,we provide stability improvement methods and representative applications.Finally,we propose the current challenges and future perspectives of the promising materials. 相似文献
8.
KANG Yun YE Cheng-chun LUO Zheng-qian SI Miao-ling 《光电子快报》2007,3(2):112-114
The characteristics of chirped and phase-shifted fiber Bragg gratings have been investigated by the use of transfer matrix formulation. While the characteristics of a chirped and phase-shifted fiber Bragg grating are the same as those of non- chirped one in some important aspects, both the reflection and transmission windows of a chirped and phase-shifted fiber Bragg grating can be broadened in a wide range. Therefore, chirped and phase-shifted fiber Bragg gratings will have applications in WDM or DWDM optical communication systems. The work in this paper can be used to design the new devices based on chirped and phase-shifted fiber Bragg gratings. 相似文献
9.
Internet of Vehicles(IoV)is a new style of vehicular ad hoc network that is used to connect the sensors of each vehicle with each other and with other vehicles’sensors through the internet.These sensors generate different tasks that should be analyzed and processed in some given period of time.They send the tasks to the cloud servers but these sending operations increase bandwidth consumption and latency.Fog computing is a simple cloud at the network edge that is used to process the jobs in a short period of time instead of sending them to cloud computing facilities.In some situations,fog computing cannot execute some tasks due to lack of resources.Thus,in these situations it transfers them to cloud computing that leads to an increase in latency and bandwidth occupation again.Moreover,several fog servers may be fuelled while other servers are empty.This implies an unfair distribution of jobs.In this research study,we shall merge the software defined network(SDN)with IoV and fog computing and use the parked vehicle as assistant fog computing node.This can improve the capabilities of the fog computing layer and help in decreasing the number of migrated tasks to the cloud servers.This increases the ratio of time sensitive tasks that meet the deadline.In addition,a new load balancing strategy is proposed.It works proactively to balance the load locally and globally by the local fog managers and SDN controller,respectively.The simulation experiments show that the proposed system is more efficient than VANET-Fog-Cloud and IoV-Fog-Cloud frameworks in terms of average response time and percentage of bandwidth consumption,meeting the deadline,and resource utilization. 相似文献
10.
The Au/n-Si Schottky barrier diodes (SBDs) with 200-μm (sample D200) and 400-μm (sample D400) bulk thicknesses have been fabricated.
The ideality factor and the barrier height have been calculated from the forward-bias current-voltage (I-V) characteristics
of D200 and D400 SBDs. The energy distribution of the interface states and relaxation time are found from the capacitance-frequency
(C-f) characteristics. The density of interface state and relaxation times have a (nearly constant) slow exponential rise
with bias in the range of Ec −0.77 and Ec −0.47 eV from the midgap toward the bottom of the conductance band. Furthermore, the energy distribution of the interface
states obtained from C-f characteristics has been compared with that obtained from the forward-bias I-V characteristics. 相似文献
11.
To enhance the security of user data in the clouds, we present an adaptive and dy- namic data encryption method to encrypt user data in the mobile phone before it is uploaded. Firstly, the adopted data encryption algorithm is not static and uniform. For each encryption, this algorithm is adaptively and dynamically selected from the algorithm set in the mobile phone encryption system. From the mobile phone's character, the detail encryption algo- rithm selection strategy is confirmed based on the user's mobile phone hardware information, personalization information and a pseudo-ran- dom number. Secondly, the data is rearranged with a randomly selected start position in the data before being encrypted. The start posi- tion's randomness makes the mobile phone data encryption safer. Thirdly, the rearranged data is encrypted by the selected algorithm and generated key. Finally, the analysis shows this method possesses the higher security be- cause the more dynamics and randomness are adaptively added into the encryption process. 相似文献
12.
Cloud computing is very attractive for schools, research institutions and enterpri- ses which need reducing IT costs, improving computing platform sharing and meeting lice- nse constraints. Sharing, management and on- demand allocation of network resources are particularly important in Cloud computing. Ho- wever, nearly all-current available cloud com- puting platforms are either proprietary or their software infrastructure is invisible to the rese- arch community except for a few open-source platforms. For universities and research insti- tutes, more open and testable experimental plat- forms are needed in a lab-level with PCs. In this paper, a platform of infrastructure resou- rce sharing system (Platform as a Service (PaaS)) is developed in virtual Cloud comput- hug environment. Its architecture, core modules, main functions, design and operational envir- onment and applications are introduced in de- tail. It has good expandability and can impr- ove resource sharing and utilization and is app- lied to regular computer science teaching and research process. 相似文献
13.
Community Question Answering (CQA) websites have greatly facilitated users' lives, with an increasing number of people seeking help and exchanging ideas on the Internet. This newlymerged community features two characteristics: social relations and an ask-reply mechanism. As users' behaviours and social statuses play a more important role in CQA services than traditional answer retrieving websites, researchers' concerns have shifted from the need to passively find existing answers to actively seeking potential reply providers that may give answers in the near future. We analyse datasets derived from an online CQA system named "Quora", and observed that compared with traditional question answering services, users tend to contribute replies rather than questions for help in the CQA system. Inspired by the findings, we seek ways to evaluate the users' ability to offer prompt and reliable help, taking into account activity, authority and social reputation char- acteristics. We propose a hybrid method that is based on a Question-User network and social network using optimised PageRank algorithm. Experimental results show the efficiency of the proposed method for ranking potential answer-providers. 相似文献
14.
Gui Yun Zhang Xu Wang Yuan Liu Ming Pei Weihu Liang Kai Huang Suibiao Li Bin Chen Hongda 《半导体学报》2013,34(10):105009-7
A multi-channel,fully differential programmable chip for neural recording application is presented.The integrated circuit incorporates eight neural recording amplifiers with tunable bandwidth and gain,eight 4thorder Bessel switch capacitor filters,an 8-to-1 analog time-division multiplexer,a fully differential successive approximation register analog-to-digital converter(SAR ADC),and a serial peripheral interface for communication.The neural recording amplifier presents a programmable gain from 53 dB to 68 dB,a tunable low cut-off frequency from 0.1 Hz to 300 Hz,and 3.77 μVrms input-referred noise over a 5 kHz bandwidth.The SAR ADC digitizes signals at maximum sampling rate of 20 kS/s per channel and achieves an ENOB of 7.4.The integrated circuit is designed and fabricated in 0.18-μm CMOS mix-signal process.We successfully performed a multi-channel in-vivo recording experiment from a rat cortex using the neural recording chip. 相似文献
15.
Apower-efficient 12-bit40-MS/spipelineanalog-to-digitalconverter(ADC)implementedina0.13 μm CMOS technology is presented. A novel CMOS bootstrapping switch, which offers a constant on-resistance over the entire input signal range, is used at the sample-and-hold front-end to enhance the dynamic performance of the pipelined ADC. By implementing with 2.5-bit-per-stage and a simplified amplifier sharing architecture between two successive pipeline stages, a very competitive power consumption and small die area can be achieved. Meanwhile, the substrate-biasing-effect attenuated T-type switches are introduced to reduce the crosstalk between the two op- amp sharing successive stages. Moreover, a two-stage gain boosted recycling folded cascode (RFC) amplifier with hybrid frequency compensation is developed to further reduce the power consumption and maintain the ADC's performance simultaneously. The measured results imply that the ADC achieves a spurious-free dynamic range (SFDR) of 75.7 dB and a signal-to-noise-plus-distortion ratio (SNDR) of 62.74 dB with a 4.3 MHz input signal; the SNDR maintains over 58.25 dB for input signals up to 19.3MHz. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) are -0.43 to +0.48 LSB and -1.62 to + 1.89 LSB respectively. The prototype ADC consumes 28.4 mW under a 1.2-V nominal power supply and 40 MHz sampling rate, transferring to a figure- of-merit (FOM) of 0.63 pJ per conversion-step. 相似文献
16.
A low phase noise and low spur phase locked loop (PLL) frequency synthesizer for use in global navigation satellite system (GNSS) receivers is proposed. To get a low spur, the symmetrical structure of the phase frequency detector (PFD) produces four control signals, which can reach the charge pump (CP) simultaneously, and an improved CP is realized to minimize the charge sharing and the charge injection and make the current matched. Additionally, the delay is controllable owing to the programmable PFD, so the dead zone of the CP can be eliminated. The output frequency of the VCO can be adjusted continuously and precisely by using a programmable LC-TANK. The phase noise of the VCO is lowered by using appropriate MOS sizes. The proposed PLL frequency synthesizer is fabricated in a 0.18 μm mixed-signal CMOS process. The measured phase noise at 1 MHz offset from the center frequency is -127.65 dBc/Hz and the reference spur is -73.58 dBc. 相似文献
17.
18.
This paper presents a low power 9-bit 80 MS/s SAR ADC with comparator-sharing technique in 130 nm CMOS process. Compared to the conventional SAR ADC, the sampling phase is removed to reach the full efficiency of the comparator. Thus the conversion rate increases by about 20% and its sampling time is relaxed. The design does not use any static components to achieve a widely scalable conversion rate with a constant FOM. The floorplan of the capacitor network is custom-designed to suppress the gain mismatch between the two DACs. The 'set-and- down' switching procedure and a novel binary-search error compensation scheme are utilized to further speed up the SA bit-cycling operation. A very fast logic controller is proposed with a delay time of only 90 ps. At 1.2 V supply and 80 MS/s the ADC achieves an SNDR of 51.4 dB and consumes 1.86 mW, resulting in an FOM of 76.6 fJ/conversion-step. The ADC core occupies an active area of only 0.089 mm2. 相似文献
19.
A low power high gain gain-controlled LNA + mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load. Its gain-controlled ability is achieved using a programmable bias circuit. Taking advantage of the high gain LNA, a high noise figure passive mixer is adopted. With the passive mixer, low power consumption and high voltage gain of the LNA + mixer are achieved. To fully investigate the performance of this circuit, comparisons between a conventional LNA + mixer, a previous low power LNA + mixer, and the proposed LNA + mixer are presented. The circuit is implemented in 0.18 #m mixed-signal CMOS technology. A 3.8 dB noise figure, an overall 45 dB converge gain and a 10 dB controlled gain range of the two stages are measured. The chip occupies 0.24 mm2 and consumes 2 mA current under 1.8 V supply. 相似文献
20.
一种应用于GPS接收机的高线性度SiGe HBT低噪声放大器 总被引:1,自引:1,他引:0
A high linearity 1.575 GHz SiGe:HBT low noise amplifier (LNA) for global positioning system applications is described. The bipolar cascoded with an MOSFET LNA was fabricated in a commercial 0.18 μm SiGe BiCMOS process, A resistor bias feed circuit with a feedback resistor was designed for the LNA input transistor to improve its intermodulation and compression performance. The packaged chip tested on board has displayed a noise figure of 1. I 1 dB, a power gain of 18 dB, an output 1 dB compression point of +7.8 dBm and an input third-order intercept point of +1.8 dBm. The chip occupies a 500 × 560μm^2 area and consumes 3.6 mA from a 2.85 V power supply. 相似文献