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1.
基于一种新的非参数方法计算了HDR (high data rate)无线网络的吞吐率容量区域. 首先把HDR吞吐率容量区域的计算问题转化为一个不带参数的数学优化问题, 然后通过贪婪算法求解得到该优化问题的解, 从而最终给出了HDR吞吐率容量区域的非参数解析刻划. 与传统的参数化方法的庞大计算量相比, 该方法的计算复杂度降低很多, 最多只需要计算N(M2-M 1)N-1个线性约束即可, 其中N为用户数, M为系统支持速率数. 数值计算例子验证了这种非参数方法的正确性. 相似文献
2.
基于迭代的比特和功率分配机制,提出了一种低复杂度的比特和功率分配算法.与传统的迭代分配算法不同,该算法在每次迭代中只需要比较几个特定的子载波.该方法在保持传统迭代算法性能的前提下极大地减小了迭代分配算法的复杂度.此外,通过选择等功率分配方案作为初始方案加快了算法的收敛速度,进一步降低了算法复杂度.仿真结果表明,提出的改进算法在基本不牺牲系统性能的前提下有效地降低了算法复杂度. 相似文献
3.
为了满足实际应用中对算法速度以及能耗的需要,提出了一种优化的SHA-1算法.该算法将环展开与预处理2种方法相结合,通过在迭代过程中引入中间变量,并且对中间变量进行预先计算,使原本单线程的运算能够多线程地并行运行.这种并行性缩短了散列函数操作的关键路径,将循环周期从原来的80缩减到了41,运算速率得到了提高,运算时所需的芯片面积也得以减少,从而降低了能耗.该算法在FPGA中硬件实现时的吞吐率高达1.2 Gbit/s,时钟频率最高为91 MHz,在吞吐率与时钟频率方面取得了较好的平衡.仿真结果表明,与其他SHA-1的改进算法相比,该优化算法在没有影响经典算法安全性的基础上,获得了较高的吞吐率和较快的速率. 相似文献
4.
求解非线性互补问题的一种方法是将其转化为非光滑方程组。本文通过引进一个基于Fischer-Burmeister函数的光滑NCP函数[8],建立了求解P0函数非线性互补问题的一个新的光滑牛顿算法。这个算法在每步迭代中只需要解一个光滑方程且不要求给出具体光滑因子下降的过程。在一定的条件下,证明了该算法的全局收敛性。数值试验表明该算法是有效的. 相似文献
5.
研究了广义绝对值方程的求解问题.在特定条件下,得到含有广义绝对值方程准确解的初始区间,然后提出了一个能不断缩小含解区间的区间迭代算法.该算法能同步显示绝对值方程近似解和准确解的误差范围,并证明了算法的收敛性且收敛速度至少是线性的.为提高计算效率,利用点迭代来代替区间迭代,最后进行了数值实验.理论分析和数值结果均表明所提算法是有效的. 相似文献
6.
基于截断投影方法,构造了求解半正定病态积分方程的Lavrentiev截断快速算法,给出了先验误差估计,并提出了新的后验参数选择准则,与传统投影方法相比得到了相同的最优收敛率,但内积的计算个数少于传统投影方法. 相似文献
7.
基于多尺度投影方法,构造了求解半正定病态积分方程的截断快速Lavrentiev迭代算法,并给出了新的后验参数选择办法.与传统全投影方法相比,减少了内积计算个数,保持了最优收敛率.最后,算例验证了算法的有效性. 相似文献
8.
针对线性规划问题,提出了一种新的内点算法一宽邻域预估校正算法．该算法基于精典预估校正思想,把窄邻域拓展到一个宽邻域里使得算法更快地迭代,给出了该算法的具体步骤,讨论了其算法的计算复杂性,分析结果表明,所给方法是一多项式时间算法,通过数值实验验证该算法的有效性． 相似文献
9.
在图像拼接技术中,单应性矩阵是实现两幅图像正确拼接的关键因素。针对传统RANSAC算法误匹配点概率较高,需要设置固定的投影误差阈值t导致迭代次数多、运行时间长、估计的单应性矩阵精度低等问题,提出一种改进的RANSAC算法以降低误匹配率。利用特征点周围灰度梯度相似性,剔除初始匹配中部分误匹配点,以减少矩阵估计的迭代次数;通过快速舍弃错误的单应性矩阵以减少内点检测时间,提高算法运行效率;通过BGD算法最小化损失函数以拟合精确的单应性矩阵。对比实验结果表明,改进的RANSAC算法能够有效剔除误匹配点,减少内点检测时间,提高单应性矩阵H的精度。 相似文献
10.
吴胜阳 《新乡师范高等专科学校学报》2006,20(5):46-48
讨论了变步长自适应滤波算法,给出了一种新的变步长LMS自适应算法,建立了步长因子μ与迭代次数n及输入信号之间的一种新的非线性函数关系。该算法与传统LMS算法相比,在计算量增加不太大的情况下,具有更快的收敛速度和较小的稳态误差,而且无须去关心步长因子的大小。通过Matlab模拟仿真的结果与理论分析相一致,证实了该算法的优越性。 相似文献
11.
一类迭代系统的混沌序列生成及其特性研究 总被引：2，自引：0，他引：2
提出了一种基于一元四次迭代系统的混沌序列生成方法.数值实验和分析结果表明,在一定参数范围内,该迭代系统生成的混沌序列具有良好的相关特性,其动力学行为比Logistic系统更为复杂. 相似文献
12.
Factors such as errors during the fabrication or construction of structural components and errors of calculation assumption or calculation methods, are very likely to cause serious deviation of many strings＇ actual prestressing forces from the designed values during tension structure construction or service period, and further to threaten the safety and reliability of the structure. Aiming at relatively large errors of the prestressing force of strings in a tension structure construction or service period, this paper proposes a new finite element method （FEM）, the ＂tensile force correction calculation method＂. Based on the measured prestressing forces of the strings, this new method applies the structure from the zero prestressing force status approach to the measured prestressing force status for the first phase, and from the measured prestressing force status approach to the designed prestressing force status for the second phase. The construction tensile force correction value for each string can be obtained by multi-iteration with FEM. Using the results of calculation, the strings＇ tensile force correction by group and in batch will be methodic, simple and accurate. This new calculation method can be applied to the prestressed correction construction simulation analysis for tension structures. 相似文献
13.
将Solodov和Svaiter于2000年发表的Error bounds for proximal point subproblems and associated inexact proximal point algorithms一文中提出的方法进行推广,得到2类近似邻近点算法．这2类算法都是预测校正方法,预测点满足相同的非精确准则,不同之处在于校正步的下降方向．为了使每次迭代产生的迭代点更加靠近解点,在校正步均采用了最优步长的技巧．在一定条件下,可以证明这2种邻近点算法是全局收敛的．并且,从理论上证明了采用算法2每一步所产生的下降量的下界大于算法1的,所以算法2比算法1能更快地收敛到解点．数值试验也表明了这一点． 相似文献
14.
与相干检测相比传统差分检测会带来约3 dB的性能损失.提出一种新的差分酉空时调制检测方案.该方案分为2步:首先将传统差分检测获得的数据序列进行差分再编码,作为对发送符号序列的初始估计;然后由期望最大化(EM)算法进行迭代检测,利用上一步得到的发送符号序列的初始估计值作为EM算法的初始值.在每一次迭代时,最新检测到的发送符号序列用来进行信道估计,随后利用估计出的信道实施相干序列检测,进一步提高对发送符号序列检测的准确性.仿真结果表明,经过几次迭代后,提出的检测方案性能大大优于传统的差分酉空时调制检测方案. 相似文献
15.
Interior-point methods （IPMs） for linear optimization （LO） and semidefinite optimization （SDO） have become a hot area in mathematical programming in the last decades. In this paper, a new kernel function with simple algebraic expression is proposed. Based on this kernel function, a primal-dual interior-point methods （IPMs） for semidefinite optimization （SDO） is designed. And the iteration complexity of the algorithm as O（n^3/4 log n/ε） with large-updates is established. The resulting bound is better than the classical kernel function, with its iteration complexity O（n log n/ε） in large-updates case. 相似文献
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17.
As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in multi-path fading channel. However, when there are frequency offsets during the signal transmission, the inter-carrier interference （ICI） is introduced, which significantly degrades the performance. The existing ICI self-cancellation schemes such as PCC-OFDM are not optimum to minimize the interference considering both noise and ICI. In this paper, a new metric named S1NR （signal-to-interference- and-noise ratio） is proposed. We discuss the optimization issue when a constant frequency offset exists and in time-varying channels. The optimum weighting-coefficient-pair （OWCP） is obtained, which maximizes SINR theoretically through the alternant iteration algorithm. Simulations show that the performance of OWCP-OFDM is better than that of PCC-OFDM, especially when the frequency offset is large. Although the ICI self-cancellation scheme suffers bandwidth inefficiency, from the simulation results we can also see that the performance of OWCP-OFDM is much better than that of the standard OFDM systems with the same bandwidth efficiency when a frequency offset exists. Moreover, since the redundant modulation provides the capability to suppress ICI as well as a receiving SNR gain, it can be considered as exchanging the bandwidth for SNR. 相似文献
18.
InOctober 2 0 0 0 ,theNationalInstituteofStandardsandTechnology (NIST)decidedtoproposeRijndaelcipherastheadvancedencryptionstandard (AES) .ItisexpectedthatAESwillbeusedbyU .S.Governmentandtheprivatesec tor,andislikelytobecomethedefactoworldwideencryptionstandardtoprotectallkindsofsecretcommunicationinthefollowingseveraldecades,whichwillinevitablycreatealargedemandforefficientimplementationofAES ,especiallyinhardware.CPLD/FPGAhasbeenprovedtobeveryeffectiveinimplementingencryptionalgo… 相似文献
19.
李晓南 《湖州师范学院学报》2010,32(2)
通过研究一种相对于Mann型和Ishikawa型进一步推广的迭代方式,给出了Banach空间中有限个非扩张映射逼近序列的强收敛定理.该结论不仅推广了文献[2]中Chidume 和Shahzad的结论,而且弱化了原定理中对非扩张映射的要求,去掉了"半紧"的限制条件. 相似文献
20.
Instructional design is not a linear process: designers have to weigh the advantages and disadvantages of alternative solutions,
taking into account different kinds of conflicting and changing constraints. To make sure that they eventually choose the
most optimal one, they have to keep on collecting information, reconsidering continuously whether their own decisions are
still justified in the light of the latest insights. We have studied the role of iteration during instructional design. For
our research, we have used an ISD-based method for the specification of training simulators. During our empirical evaluation
study, we introduced five events that are likely to cause iteration. The results show that the quality of the designs is not
directly related to the amount of iteration. We conclude that there are different kinds of iteration, triggered by different
kinds of actions and events. We propose a list of triggers for iteration some of which originate from outside (new information,
new opinions/arguments and acquisition procedures); others are caused by, or evolve from interaction with the design process
itself (discovery of missing input, need to repair errors, new insights based on work later on in the design process, and
new ideas of the designers).
in final form: 4 August 2005 相似文献