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61.
In this paper, we present a fast Fourier transform (FFT) processor with four parallel data paths for multiband orthogonal frequency‐division multiplexing ultra‐wideband systems. The proposed 128‐point FFT processor employs both a modified radix‐24 algorithm and a radix‐23 algorithm to significantly reduce the numbers of complex constant multipliers and complex booth multipliers. It also employs substructure‐sharing multiplication units instead of constant multipliers to efficiently conduct multiplication operations with only addition and shift operations. The proposed FFT processor is implemented and tested using 0.18 µm CMOS technology with a supply voltage of 1.8 V. The hardware‐ efficient 128‐point FFT processor with four data streams can support a data processing rate of up to 1 Gsample/s while consuming 112 mW. The implementation results show that the proposed 128‐point mixed‐radix FFT architecture significantly reduces the hardware cost and power consumption in comparison to existing 128‐point FFT architectures. 相似文献
62.
This paper generalizes the C*-dynamical system to the Banach algebra dynamical system(A,G,α)and define the crossed product A α G of a given Banach algebra dynamical system(A,G,α).Then the representation of A α G is described when A admits a bounded left approximate identity.In a natural way,the authors define the reduced crossed product A α,r G and discuss the question when A α G coincides with A α,r G. 相似文献
63.
The concept of balance vertices was first investigated by Reid (1999). For the main result “the balance vertices of a tree consist of a single vertex or two adjacent vertices”, Shan and Kang (2004) and Reid and DePalma (2005) improved the length and technique of the proof. In this paper we further discuss the balance vertices on trees in a generalization context. We do not only provide a simple efficient proof for the relevant result but also develop a linear time algorithm to find the set of balance vertices on the underlying tree. 相似文献
64.
Effective Relaxations and Partitioning Schemes for Solving Water Distribution Network Design Problems to Global Optimality 总被引:2,自引:0,他引:2
Hanif D. Sherali Shivaram Subramanian G.V. Loganathan 《Journal of Global Optimization》2001,19(1):1-26
In this paper, we address the development of a global optimization procedure for the problem of designing a water distribution network, including the case of expanding an already existing system, that satisfies specified flow demands at stated pressure head requirements. The proposed approach significantly improves upon a previous method of Sherali et al. (1998) by way of adopting tighter polyhedral relaxations, and more effective partitioning strategies in concert with a maximal spanning tree-based branching variable selection procedure. Computational experience on three standard test problems from the literature is provided to evaluate the proposed procedure. For all these problems, proven global optimal solutions within a tolerance of 10–4% and/or within 1$ of optimality are obtained. In particular, the two larger instances of the Hanoi and the New York test networks are solved to global optimality for the very first time in the literature. A new real network design test problem based on the Town of Blacksburg Water Distribution System is also offered to be included in the available library of test cases, and related computational results are presented. 相似文献
65.
Martin Gugat 《Mathematical Programming》1999,85(3):643-653
The growth of the multipliers, when the parameter approaches such a critical parameter, is characterized by a parametric constraint qualification which is introduced here. It is equivalent to a bound on the growth of the multipliers. Received May 8, 1995 / Revised version received February 12, 1998 Published online February 25, 1999 相似文献
66.
《Mathematische Nachrichten》2017,290(5-6):913-919
We consider grand Lebesgue spaces on sets of infinite measure and study the dependence of these spaces on the choice of the so‐called. We also consider Mikhlin and Marcinkiewicz theorems on Fourier multipliers in the setting of grand spaces. 相似文献
67.
John A. Taylor Peter E. Tannenwald Neal R. Erickson Gerald F. Dionne James F. Fitzgerald 《International Journal of Infrared and Millimeter Waves》1985,6(8):687-695
A compact, solid state submillimeter-wave heterodyne radiometer has been developed and was used to measure spectral characteristics of a water vapor jet in a space simulation chamber. Features of the 557 GHz water vapor line profile were observed in significantly greater detail than in previous experiments through an increased sensitivity and improved frequency resolution (600 kHz). The local oscillator of the radiometer consisted of a frequency multiplication chain which was driven by an InP Gunn oscillator at 92.6 GHz, and which contained a frequency tripler and harmonic mixer in cascade. The front end of the receiver had a noise temperature of 4500 K (DSB) at 555 GHz, consumed 3 W and weighed 3 kg. This advance in technology is particularly relevant to submillimeter-wave radiometry from a space-based platform. 相似文献
68.
本文基于GaAs肖特基势垒二极管以及混合集成电路工艺,对太赫兹固态倍频和检测技术开展了研究.文章结合肖特基势垒二极管物理结构,采用电磁场仿真软件和电路仿真软件相结合的综合分析方法,对各模块电路进行优化设计,研制出了高倍频效率的倍频源和高灵敏度的检测器(检波器和谐波混频器).0.15THz检波器测得最高检波电压灵敏度1600mV/mW,在0.11~0.17THz灵敏度典型值为600mV/mW,切线灵敏度优于-29dBm.0.15THz二倍频器测得最高倍频效率7.5%,在0.1474~0.152THz效率典型值为6.0%.0.18THz二倍频器测得最高倍频效率14.8%,在0.15~0.2THz效率典型值为8.0%.0.15THz谐波混频器测得最低变频损耗10.7dB,在0.135~0.165THz变频损耗典型值为12.5dB.0.18THz谐波混频器测得最低变频损耗5.8dB,在0.165~0.2THz变频损耗典型值为13.5dB,在0.21~0.24THz变频损耗典型值为11.5dB. 相似文献
69.
We prove three modular equations of Ramanujan using theta-function identities. Proofs via methods known to Ramanujan were not available hitherto. One had previously been proved by classical methods, and two had been proved using the theory of modular forms. 相似文献
70.