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1.
A variable-power (VP) adaptive modulation (AM) scheme with space-time block code (STBC) is developed in MIMO systems, and the corresponding performance is investigated in Nakagami fading channels. The optimum switching thresholds are derived so that the spectrum efficiency (SE) under an average power and a target bit error rate (BER) constraint is maximized. By the switching thresholds, average BER and SE are further derived. As a result, closed-form expressions are obtained. Besides, the exact and approximate BER expressions of VP AM and constant-power (CP) AM systems with delayed feedback are respectively derived. Simulation results show that the theoretical SE and BER can match the corresponding simulation well. The results indicate that VP-AM with STBC provide higher spectrum efficiency than the CP counterparts, and has slighter bite error rate performance degradation when the normalized delay is less than 0.01.  相似文献   

2.
Outlier detection on data streams is an important task in data mining. The challenges become even larger when considering uncertain data. This paper studies the problem of outlier detection on uncertain data streams. We propose Continuous Uncertain Outlier Detection (CUOD), which can quickly determine the nature of the uncertain elements by pruning to improve the efficiency. Furthermore, we propose a pruning approach -- Probability Pruning for Continuous Uncertain Outlier Detection (PCUOD) to reduce the detection cost. It is an estimated outlier probability method which can effectively reduce the amount of calculations. The cost of PCUOD incremental algorithm can satisfy the demand of uncertain data streams. Finally, a new method for parameter variable queries to CUOD is proposed, enabling the concurrent execution of different queries. To the best of our knowledge, this paper is the first work to perform outlier detection on uncertain data streams which can handle parameter variable queries simultaneously. Our methods are verified using both real data and synthetic data. The results show that they are able to reduce the required storage and running time.  相似文献   

3.
The block cipher used in the Chinese Wireless LAN Standard (WAPI), SMS4, was recently renamed as SM4, and became the block cipher standard issued by the Chinese government. This paper gives a method for finding the linear approximations of SMS4. With this method, 19-round one-dimensional approximations are given, which are used to improve the previous linear cryptanalysis of SMS4. The 19-round approximations hold with bias 2-62.27; we use one of them to leverage a linear attack on 23-round SMS4. Our attack improves the previous 23-round attacks by reducing the time complexity. Furthermore, the data complexity of our attack is further improved by the multidimensional linear approach.  相似文献   

4.
We describe the trace representations of two families of binary sequences derived from the Fermat quotients modulo an odd prime p (one is the binary threshold sequences and the other is the Legendre Fermat quotient sequences) by determining the defining pairs of all binary characteristic sequences of cosets, which coincide with the sets of pre-images modulo p2 of each fixed value of Fermat quotients. From the defining pairs, we can obtain an earlier result of linear complexity for the binary threshold sequences and a new result of linear complexity for the Legendre Fermat quotient sequences under the assumption of 2p-1≠ 1 mod p2.  相似文献   

5.
This paper discusses optimal binary codes and pure binary quantum codes created using Steane construction. First, a local search algorithm for a special subclass of quasi-cyclic codes is proposed, then five binary quasi-cyclic codes are built. Second, three classical construction methods are generalized for new codes from old such that they are suitable for constructing binary self-orthogonal codes, and 62 binary codes and six subcode chains of obtained self-orthogonal codes are designed. Third, six pure binary quantum codes are constructed from the code pairs obtained through Steane construction. There are 66 good binary codes that include 12 optimal linear codes, 45 known optimal linear codes, and nine known optimal self-orthogonal codes. The six pure binary quantum codes all achieve the performance of their additive counterparts constructed by quaternary construction and thus are known optimal codes.  相似文献   

6.
The probability hypothesis density(PHD)flter provides an efciently parallel processing method for multi-target tracking.However,measurements have to be gathered for a scan period before the PHD flter can perform a recursion,therefore,signifcant delay may arise if the scan period is long.To reduce the delay in the PHD flter,we propose a sequential PHD flter which updates the posterior intensity whenever a new measurement becomes available.An implementation of the sequential PHD flter for a linear Gaussian system is also developed.The unique characteristic of the proposed flter is that it can retain the useful information of missed targets in the posterior intensity and sequentially handle the received measurements in time.  相似文献   

7.
Interval arithmetic is an elegant tool for practical work with inequalities, approximate numbers, error bounds, and more generally with certain convex and bounded sets. In this section we give a number of simple examples showing where intervals and ranges of functions over intervals arise naturally. Interval mathematics is a generalization in which interval numbers replace real numbers, interval arithmetic replaces real arithmetic, and interval analysis replaces real analysis. Interval is limited by two bounds: lower bound and upper bound. The present paper introduces some of the basic notions and techniques from interval analysis needed in the sequel for presenting various uses of interval analysis in electric circuit theory and its applications. In this article we address the representation of uncertain and imprecise information, the interval arithmetic and its application to electrical circuits.  相似文献   

8.
We previously proposed a new typhoon warning system which forecasts the likely extent of damage associated with a typhoon towards humans and buildings. The relation between typhoon data and damage data was learned by SOM (self-organizing maps) and typhoon damage scale (small, middle or large) was forecast by the SOM using typhoon data. Although average accuracy for actually small scale damage data was comparatively high (96.2%), average accuracy for actually large scale damage data was comparatively low (65.2%). Thus, we apply a selective presentation learning technique for improving the predictability of large scale damage by SOM. Learning data corresponding to middle and large scale damage are presented more often. Average accuracy for actually large scale damage data was increased by about 9%. The accuracy for actually large scale of numbers of fatalities and houses under water was increased by 25% and 20%, respectively.  相似文献   

9.
This paper presents the authors' research results about HRI (human-robot interaction). The goal is to estimate together the arm position, the anatomical movements of the shoulder and accelerations of the arm with respect to the shoulder and visualizing this movement in a 3-D virtual model to control a Robot. The estimation algorithm makes use of a nonlinear observer and an optimization routine to fuse information from the sensor. The global asymptotic convergence of the nonlinear observer is guaranteed. Extensive tests of the presented methodology with real world data show the effectiveness of the proposed procedure.  相似文献   

10.
In this paper, we provide a unified expression to obtain the conditions on the restricted isometry constant δ2s(φ). These conditions cover the important results proposed by Candes et al. and each of them is a sufficient condition for sparse signal recovery. In the noiseless case, when δ2s(φ) satisfies any one of these conditions, the s-sparse signal can be exactly recovered via (11) constrained minimization.  相似文献   

11.
This paper deals with the problem of controller design for NCSs (networked control systems) with uncertain parameters and network induced time-delays. In the case of long time delay constraint and data package loss, the closed-loop model of a class of NCSs is presented for controlled objects with uncertain parameters. Based on Lyapunov stability theory combined with LMIs (linear matrix inequalities) techniques, the design method of state feedback controller for NCSs with asymptotic stability is given in the form of LMIs. Numerical example and simulation suggest that the results are effective and are an improvement over previous ones.  相似文献   

12.
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   

13.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
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   

20.
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   

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