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从直接转矩控制的原理出发,介绍直接转矩控制减小脉动方法以及特点.虽然这些方法在一定程度上可改善直接转矩控制性能,但增加系统的复杂性.提出改善直接转矩控制性能而不增加系统复杂度,则是未来的研究重点. 相似文献
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针对HEVC视频编码中帧层比特分配和率失真模型参数自适应更新,提出了一种改进的码率控制算法.该算法引入牛顿法来自适应更新率失真模型的参数;同时提出一种帧层复杂度度量方法,利用图像自身的内容特性来调整帧层比特分配;最后在编码过程中选择合适的量化参数.实验结果表明:与参考算法比较,该算法能大大降低计算复杂度,同时保持良好的码率控制性能,对含有场景突变的视频改进效果尤为明显. 相似文献
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为了提高JVT-H017码率控制提案中的基本单元层比特数分配方法在视频序列复杂度较高时分配的准确度,提出了一种视频复杂度自适应的基本单元层码率控制方法。利用DMAD参数来判断视频场景的复杂度,对JVT-H017的比特数分配方法进行了改进;同时提出了一种基本单元层编码的理想情况,并以此理想情况下的比特数消耗情况来对基本单元的比特数进行修正。仿真结果表明,该方法有效地提高了视频编码的峰值信噪比(PSNR),最大可提高0.49 dB,并且输出码率更接近预定编码码率。 相似文献
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提出一种利用加权预测模型为基本单元分配比特数的码率控制算法,不但计算复杂度较小,且能更好地根据图像内容适当分配比特数,使恢复的图像质量进一步提高.仿真结果表明,该方法可改善图像的峰值信噪比,获得更好的主观视觉质量. 相似文献
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基于复杂度HEVC码率控制的算法优化 总被引:1,自引:0,他引:1
针对视频编码标准HEVC(high efficiency video coding)在编码过程中复杂度较高的帧层带宽相对不足而复杂度较低的帧层带宽相对富余之一的问题,为了降低计算复杂度,提高编码质量,本文首先通过研究复杂度在帧层编码过程中对码率分配的影响,提出了由SATD(sum of absolute transformed difference)构建复杂度模型,根据视频内容每帧的复杂程度,通过复杂度模型对帧层进行合理的比特分配。为了建立R-Q曲线,结合最大编码单元(LCU,largest coding unit)层的编码树特点,根据LCU残差信号的混合高斯分布特性进行量化参数(QP)的计算,从而使得输出码率与目标比特相等的同时尽可能提高视频质量。实验结果表明,所提出的算法比HEVC现行码率控制算法性能更加优良并且具有较强的鲁棒性,码率误差在0.01%以内,PSNR增益平均可达0.21dB。 相似文献
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根据虚信元丢失率和等效带宽分配的概念,提出了一种用于ATM风格中的呼叫允许接入控制的虚拟等效带宽分配算法。该方法明显提高了链路带宽的利用率,同时在业务种类较多,呼叫数量较大的情况下,比理论计算方法在计算复杂度上有很大的改善,因而便于实时控制。 相似文献
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交流电机直接转矩控制改进方案 总被引:1,自引:0,他引:1
从直接转矩控制的原理出发.介绍直接转矩控制减小脉动方法以及特点。虽然这些方法在一定程度上可改善直接转矩控制性能,但增加系统的复杂性。提出改善直接转矩控制性能而不增加系统复杂度,则是未来的研究重点。 相似文献
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在随机有限集多目标跟踪过程中,由于跟踪问题的复杂性,会耗费大量的计算成本,特别是在目标和杂波密集的复杂情况中,计算成本呈指数增长。随机有限集中通常采用的分配算法——例如Murty算法的时间复杂度为滤波器生成的代价矩阵规模的三次方。为了减少跟踪耗时,结合组合优化的思想,将代价矩阵重定义为二分图,采用了一种基于深度强化学习的二分图匹配算法,取代传统随机有限集中的分配算法,并通过仿真实验验证了所提方法的可行性。实验表明,所提方法在保证跟踪性能的前提下减少了跟踪耗时,提升了跟踪实时性。 相似文献
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A new hybrid method that removes typical discontinuities and singularities of UTD solutions is described and applied to scattering by complex structures. The scattered fields from the structure are first computed on a surface S enclosing it. Then these fields are used to compute an equivalent set of electric and magnetic currents, which are then used to find the scattered fields from the structure. This method can extend the ability of available UTD computer codes to solve for the scattered fields from structures that need special treatment and are nor solvable through direct UTD means. Good agreement is shown between this new hybrid method and moment method results as well as measurements 相似文献
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Utility‐optimal cross‐layer resource allocation in distributed wireless cooperative networks 下载免费PDF全文
Haixia Cui Gang Wei Han Zhang Qinghua Zhong 《International Journal of Communication Systems》2014,27(2):277-288
In this paper, we propose a distributed cross‐layer resource allocation algorithm for wireless cooperative networks based on a network utility maximization framework. The algorithm provides solutions to relay selections, flow pass probabilities, transmit rate, and power levels jointly with optimal congestion control and power control through balancing link and physical layers such that the network‐wide utility is optimized. Via dual decomposition and subgradient method, we solve the utility‐optimal resource allocation problem by subproblems in different layers of the protocol stack. Furthermore, by introducing a concept of pseudochannel gain, we model both the primal direct logical link and its corresponding cooperative transmission link as a single virtual direct logical link to simplify our network utility framework. Eventually, the algorithm determines its primal resource allocation levels by employing reverse‐engineering of the pseudochannel gain model. Numerical experiments show that the convergence of the proposed algorithm can be obtained and the performance of the optimized network can be improved significantly. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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针对多径信道下直接序列扩频信号检测的难题,在基于自相关二阶矩的检测算法基础上提出了新的检测参数,从而将加性高斯白噪声信道下的直接序列扩频信号检测算法推广到多径信道。本文算法首先分析了由多径信道导致的能量峰值和由直扩信号的伪码特性导致的自相关峰值的特点,并根据此特点定义了新的检测参数——多径因子,最后将该参数应用到基于自相关二阶矩的直接序列扩频信号检测算法中,实现了对多径信道下的直接序列扩频信号的检测。理论分析和仿真实验表明,本文提出的检测新参数能真实的反映多径信道对信号自相关函数的影响;当信噪比大于-14dB时,本文提出的多径信道下直扩信号检测算法性能与加性高斯白噪声信道下的检测性能相当。 相似文献
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该文根据线性模型提出信源内容复杂度的一种度量方式,并以此进行帧级比特分配和宏块级的视频码率控制。仿真表明该方法与MPEG2中的TM5相比,能比较显著地提高信噪比,实现更加准确的码率控制,同时可以在帧间和帧内获得更一致的视觉效果。该算法在MPEG4及低码率视频编码中也是适用的。 相似文献
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一个利用模糊预测的ATM广域网流量控制算法 总被引:6,自引:0,他引:6
本文提出了一个采用模糊预测的ATM广域网流量控制算法,该算法包括二个部分,即非受控业务量的模糊预测和网络带宽的动态分配,在预测部分,提出了一组模糊判决规则和相关的隶属函数,在带宽分配地对ATM广域网传输时延长的特点,把模糊预测与本文作者在文献「1」中所提出的SER流量控制机制相结合,保证了带分配的公平性和链路的高利用率,仿真结果表明,带宽分配具有公平性,链路利用率达到设计目标、交换节点处缓冲队列很 相似文献
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《Mechatronics》2015
A significant challenge in electric vehicles with multiple motors is how to control the individual drivetrains in order to achieve measurable benefits in terms of vehicle cornering response, compared to conventional stability control systems actuating the friction brakes. This paper presents a direct yaw moment controller based on the combination of feedforward and feedback contributions for continuous yaw rate control. When the estimated sideslip exceeds a pre-defined threshold, a sideslip-based yaw moment contribution is activated. All yaw moment contributions are entirely tunable through model-based approaches, for reduced vehicle testing time. The purpose of the controller is to continuously modify the vehicle understeer characteristic in quasi-static conditions and increase yaw and sideslip damping during transients. Skid-pad, step-steer and sweep steer tests are carried out with a front-wheel-drive fully electric vehicle demonstrator with two independent drivetrains. The experimental test results of the electric motor-based actuation of the direct yaw moment controller are compared with those deriving from the friction brake-based actuation of the same algorithm, which is a major contribution of this paper. The novel results show that continuous direct yaw moment control allows significant “on-demand” changes of the vehicle response in cornering conditions and to enhance active vehicle safety during extreme driving maneuvers. 相似文献
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基于率失真理论的视频编码码率控制 总被引:13,自引:5,他引:8
本文以率失真理论为基础,提出了一种新的前向视频编码码率控制策略FRC,其核心思想是:宏块目标比特数的预分配除受码率的限制外,更重要的是受到图像的局部空间活动性等因素的控制,从而达到一种最优的比特分配方案。主观测试实验结果表明,这种新的码率控制策略大大地改善了重建图像的质量。 相似文献
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《Mechatronics》2023
This paper presents the control and experiments of a novel multirotor aerial platform, which is capable of full actuation for six Degree of Freedom (DoF) motions. The platform is actuated by a number of tilting-thrust modules, each consisting of a regular quadcopter and a mechanically passive hinge. The platform in this paper has four such actuator modules, making an over-actuated system that requires input allocations in the feedback control. In addition to the common least-square method that minimizes the sum of squares of the thrusts, we propose a control allocation that minimizes the maximum thrust in a closed-form analytical solution for efficient real time computation. This allocation can achieve larger inclination angles than that by the least-square method, when thrust forces are insufficient to overcome the gravity for all poses. Simulation and real world experiments are presented to demonstrate the control of the aerial platform for six DoF motion tracking and disturbance rejection. 相似文献