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1.
Aiming at the series of errors processing and analyzing produced in three-dimensional testing and reconstruction of the highway pavements, this paper conducts a detailed analysis and computation of these process errors, including calibration of signalized points, centerline calculation of light stripe, accumulated system error, etc.. After the contrast experiment and analysis, it finally introduces gravity method to calculate the camera's internal parameters, and gray centroid algorithm to extract light stripes' center. Result shows the system deviation is stabilized at 2 mm, which can better meet the needs of engineering practice.  相似文献   

2.
摘要:为了更好的研究LDPC码的错误平层现象,本文提出了一种利用重要抽样信息的仿真方法。在AWGN信道下,当误比特率极低时,该方法相比于传统的蒙特卡洛方法在保证仿真质量不变的情况下,取得了极高的仿真增益。利用该方法可以仿真到传统蒙特卡罗方法无法仿真到的仿真区域。仿真结果表明,对于一个码长为2000,码率为1/2的LDPC码字,当误比特率为10-20 时,该方法取得1014以上的仿真增益。  相似文献   

3.
对采用TCP协议传输数据的实现过程及其在无线网络中可能遇到的问题进行了描述,针对这些问题提出了一种算法对无线链路下一时刻的误码率进行了估计,根据这个估计对TCP进行了修改以自适应选取合适的TCP报文段尺寸来传输数据。在网络仿真器(NS2)中仿真一个误码率时变的无线信道,把修改后的TCP置于NS仿真环境中进行仿真,实验结果表明了该改进方法有效。  相似文献   

4.
线性复杂度和k-错线性复杂度是研究流密码稳定性的两个重要概念。当改变序列某几位时不会使得序列的线性复杂度急剧减少,说明该序列的稳定性良好。运用Chan-Games给出了当k=4或5时,F2上固定线性复杂度为2n-2m-1的2n-周期二元序列的k-错线性复杂度所有可能值,LCk(s)=0或LCk(s)=2n-2m-2r+1+c,LCk(s)=2n-2r+1+c。这一结果对流密码稳定性的研究有重要的应用价值。  相似文献   

5.
This paper represents a comparative performance evaluation of different diversity combining techniques for a SIMO-OFDM (single-input-multiple-output orthogonal frequency division multiplexing) system over Rayleigh fading channel. OFDM is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems. But in scattering environment, the system performances are severely degraded by the effects of multipath fading and inter-symbol interference. In wireless communication systems, antenna diversity is an important technique to combat multipath fading in order to improve the system performance and increase the channel capacity. In this paper, the performance of different diversity combining techniques-SC (selection combining), EGC (equal gain combining) and MRC (maximal ratio combining) has been analyzed and compared in terms of SNR (signal to noise ratio) and BER (bit error rate) probability. The simulation results show that the maximal ratio combining technique provides maximum performance improvement relative to all other combining schemes by maximizing the SNR of SIMO-OFDM system at the combiner output. The analytic expressions of error probability and effective bit energy to noise ratio correlated with BPSK (binary phase shift keying) modulation have been derived and formulated for N-branch SC, EGC and MRC schemes. The BER characteristics for all three combining techniques are simulated in MATLAB (matrix laboratory) tool box for varying bit energy to noise ratio. Our results also derives that SNR can be improved if the number of receiving antenna is increased, which in turn reduces BER over a Rayleigh fading channel.  相似文献   

6.
WSNs (wireless sensor networks) consist of thousands of tiny nodes having the capability of sensing, computation, and wireless communications. Unfortunately these devices are limited energy devices, that is means we must save energy as much as possible, to increase network life time as long as possible. In this paper we introduce NEER--normalized energy efficient routing protocol that increases network life time through switching between AODV protocol that depends on request-reply routing, and MRPC that depends on residual battery in routing.  相似文献   

7.
An incubator is an organization that supports new ventures to grow and survive during the early stages. Mainly dedicated to information technology, life science may appear to be the next hot spot for incubators. Are there stabilized good practices? Are the business models in information technology and in life science comparable when it goes to start-ups' incubation? Leveraging our experience as practitioner in this field and using an inductive methodology, this paper tends to propose simple principles to help build robust incubators in life science, and to contribute to disseminate an entrepreneurial approach through an industry still dominated by blue chips.  相似文献   

8.
Our study proposes a new local model to accurately control an avatar using six inertial sensors in real-time.Creating such a system to assist interactive control of a full-body avatar is challenging because control signals from our performance interfaces are usually inadequate to completely determine the whole body movement of human actors.We use a pre-captured motion database to construct a group of local regression models,which are used along with the control signals to synthesize whole body human movement.By synthesizing a variety of human movements based on actors’control in real-time,this study verifies the effectiveness of the proposed system.Compared with the previous models,our proposed model can synthesize more accurate results.Our system is suitable for common use because it is much cheaper than commercial motion capture systems.  相似文献   

9.
目前,日本已开发出一种多路PCM伴音卫星广播传输方式,该方式采用PCM多路高音质伴音时分复接的方法。本文主要描述了这种伴音传输方式的准瞬时压扩技术、误码控制技术、比特交织技术和加扰技术,并对它们进行了计算机模拟,采用当前广泛应用的C~( )语言作为工具。  相似文献   

10.
The purpose of this exploratory research was to study the relationship between the mood of computer users and their use of keyboard and mouse to examine the possibility of creating a generic or individualized mood measure. To examine this, a field study (n = 26) and a controlled study (n = 16) were conducted. In the field study, interaction data and self-reported mood measurements were collected during normal PC use over several days. In the controlled study, participants worked on a programming task while listening to high or low arousing background music. Besides subjective mood measurement, galvanic skin response (GSR) data was also collected. Results found no generic relationship between the interaction data and the mood data. However, the re- suits of the studies found significant average correlations be- tween mood measurement and personalized regression models based on keyboard and mouse interaction data. Together the results suggest that individualized mood prediction is pos- sible from interaction behaviour with keyboard and mouse.  相似文献   

11.
In the development of robotic limbs, the side of members is of importance to define the shape of artificial limbs and the range of movements. It is mainly significant tbr biomedical applications concerning patients suffering arms or legs injuries, fn this paper, the concept of an ambidextrous design lbr robot hands is introduced. The fingers can curl in one xvay or another, to imitate either a right hand or a left hand. The advantages and inconveniences of different models have been investigated to optimise the range and the maximum force applied by fingers. Besides, a remote control interthce is integrated to the system, allowing both to send comrnands through internet and to display a video streaming of the ambidextrous hand as feedback. Therefore, a robotic prosthesis could be used for the first time in telerehabilitation. The main application areas targeted are physiotherapy alter strokes or management of phantom pains/br amputees by/earning to control the ambidextrous hand. A client application is also accessible on Facehook social network, making the robotic limb easily reachable for the patients. Additionally the ambidextrous hand can be used tbr robotics research as well as artistic performances.  相似文献   

12.
The operation of a complicated radiators structure creating a required field in a given area is disturbed often due to different external actions. As an example, the impact of metallic objects approaching off to an antenna system with minimal irradiation on user's body is analyzed. In this case, the zone itself, where the area of a weak field (a dark spot) is created, is generally not approachable for sensors installation. In order to counteract the disturbance of the system operation due to presence of different metallic objects in close proximity to the radiators, two methods based on two information sources are studied. These information sources are antennas driving currents and fields at a predetermined point outside the given area. As an example, the antenna system used in the compensation method for reducing human's body irradiation, to which a metal object approaches, is analyzed. The conditions of severe external actions are considered: a great metal body and a small distance from this body to the dark spot. It is shown that under these conditions of severe external actions the second method based on the field values measuring demonstrates a higher efficiency. A block scheme for structure of an automatic adjustment is suggested. The considered problem is a common one, and developers of radio circuits are faced with them constantly.  相似文献   

13.
A 2.4 GHz low power transceiver for low-rate wireless personal area network(LR-WPAN)applications is presented.The optimized low-IF receiver consists of a novel current reuse RF front-end with an inductor-less-load balun LNA and quadrature mixer,and an adaptive analog baseband to reduce power and area.It achieves-94 dBm of sensitivity,-9 dBm of IIP3 and 28 dBc of image rejection.The phase-locked loop based direct phase modulated transmitter is proposed to reduce power and deliver a+3 dBm output power.The phase noise of the low power frequency synthesizer with current reuse stacked LC-VCO achieves-107.8 dBc/Hz at 1 MHz offset.An ultra-low power nonvolatile memory is used to store configuration data and save power.The chip is implemented in a 0.18μm CMOS process,and the area is less than 2.8 mm2.The transceiver consumes only 10.98 mW in the receiving mode and 13.32 mW in the transmitting mode.  相似文献   

14.
In this paper, a dual frequency resonance antenna is analysed by introducing U-shaped slot in a rectangular and circular patch, the results in terms of return loss, input impedance and radiation pattern are given. It is observed that various antenna parameters are obtained as a function of frequency for different value of slot length and width; it is easy to adjust the upper and the lower band by varying these different antenna parameters. The coaxial feed is used to excite the patch antenna. All the theoretical results using Matlab are compared with the simulated results obtained from Ansoft HFSS which are in close agreement. Furthermore, comparative study between our results and those available in the literature is done and showed to be in good agreement.  相似文献   

15.
The next generation wireless communication systems aim at supporting enhanced diversified network access and data transmission abilities via the cooperative integration and unified management of various radio access technologies(RATs).The resource allocation is the core component leading the network system and mobile terminals to the service robustness and performance maximization.In this paper,a numeric optimization model for optimizing terminals’transmission power and allocated RAT bandwidth for maximizing system capacity is proposed with the focal consideration of the multi-radio transmission diversity for parallel transmission through multiple links from diferent RATs,and diferent terminal characteristics on RAT supports.Also,we design a centralized and periodic scheduling algorithm including an improved coevolutionary genetic algorithm for efciently solving the optimization problem.Simulation results demonstrate that our propose algorithm can distinctly enhance the system performance and improve the computational efciency.  相似文献   

16.
Classical decision tree model is one of the classical machine learning models for its simplicity and effectiveness in applications. However, compared to the DT model, probability estimation trees (PETs) give a better estimation on class probability. In order to get a good probability estimation, we usually need large trees which are not desirable with respect to model transparency. Linguistic decision tree (LDT) is a PET model based on label semantics. Fuzzy labels are used for building the tree and each branch is associated with a probability distribution over classes. If there is no overlap between neighboring fuzzy labels, these fuzzy labels then become discrete labels and a LDT with discrete labels becomes a special case of the PET model. In this paper, two hybrid models by combining the naive Bayes classifier and PETs are proposed in order to build a model with good performance without losing too much transparency. The first model uses naive Bayes estimation given a PET, and the second model uses a set of small-sized PETs as estimators by assuming the independence between these trees. Empirical studies on discrete and fuzzy labels show that the first model outperforms the PET model at shallow depth, and the second model is equivalent to the naive Bayes and PET.  相似文献   

17.
An increasing number of social computational systems consist of a great amount of autonomous entities and operate in highly dynamic and unpredictable environments. To construct such systems needs to seek high-level abstrac- tion to manage the complexity of the systems and novel mechanism to support their characteristics, i.e., dynamism and flexibility. Agent-oriented programming (AOP) is con- sidered as a potential paradigm for developing such systems by exhibiting a number of characteristics, such as autonomy, flexibility, social ability, etc. However, current researches on AOP mainly focus on the construction of multi-agent system (MAS) with theory and language facilities inspired from arti- ficial intelligence (AI) and distributed AI, seldom considering and integrating the proven principles and practices of pro- gramming and software engineering. Moreover, abstractions and mechanism based on AI are inadequate for developing dynamic and flexible MAS in open environment. This paper proposes a novel AOP approach, namely Oragent, for con- structing and implementing dynamic and flexible systems. From a software engineering perspective, Oragent integrates organizational concepts and mechanism into AOP language, and support the dynamism and flexibility with explicit prim- itives. The proposed approach consists of a programming model and a corresponding programming language. This paper presents the syntax and formal operational semanticsof Oragent language, and studies a case to demonstrate our approach.  相似文献   

18.
In this paper, we provide a super-resolution image reconstruction algorithm based on wavelet transform. Wavelet transform can separate high frequency and low frequency information of image. The more high frequency information can be obtained by using wavelet transform and the technique of image fusion. Meanwhile, reconstructed super-resolution image is produced by the iterative method. In iteration process, noise of image can be suppressed by applying method of wavelet threshold de-noising. The experiment results show that the algorithm can overcome the disadvantage of the classical interpolation method and effectively improve the resolution and PSNR of the image.  相似文献   

19.
20.
Today's news readers can be easily overwhelmed by the numerous news articles online. To cope with information overload, online news media publishes timelines for continuously developing news topics. However, the timeline summary does not show the relationship of storylines, and is not intuitive for readers to comprehend the development of a complex news topic. In this paper, we study a novel problem of exploring the interactions of storylines in a news topic. An interaction of two storylines is signified by informative news events that play a key role in both storylines. Storyline interactions can indicate key phases of a news topic, and reveal the latent connections among various aspects of the story. We address the coherence between news articles which is not considered in traditional similarity-based methods, and discover salient storyline interactions to form a clear, global picture of the news topic. User preference can be naturally integrated into our method to generate query-specific results. Comprehensive experiments on ten news topics show the effectiveness of our method over alternative approaches.  相似文献   

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