Toward best-effort services over WDM networks with fair access andminimum bandwidth guarantee

Most existing wavelength-division multiplexed (WDM) networks employ circuit switching, typically with one session having exclusive use of one entire wavelength. Consequently, they are not suitable for data applications involving bursty traffic patterns. The All-Optical Network (AON) Consortium has developed an all-optical LAN/MAN test bed which provides time-slotted WDM service. We explore extensions of this service to achieve fine-grained statistical multiplexing with different virtual circuits time sharing the wavelengths in a fair manner. We develop a very fast, best effort time-slotted WDM network protocol with very good fairness and throughput characteristics. As an additional design feature, our protocol supports the assignment of guaranteed bandwidths (GBW) to selected sessions. This feature acts as a first step toward supporting integrated services at the optical layer in WDM networks     

A novel method for elimination of line-current harmonics insingle-stage PFC switching regulators

This paper studies a particular single-stage power-factor-correction (PFC) switching regulator employing a discontinuous-conduction-mode (DCM) boost-input cell and a continuous-current-mode (CCM) forward output cell. Although this single-stage PFC regulator can provide a reasonably high power factor when its PFC stage is operating in discontinuous mode, substantial reduction in line-current harmonics is possible by applying a suitable frequency-modulation scheme. This paper derives a frequency-modulation scheme and proposes a practical implementation using a simple translinear analog circuit. A quantitative analysis on the total harmonic distortion (THD) of the line current when the circuit is subject to a limited range of frequency variations is presented along with some considerations for practical design. Experimental data obtained from a prototype confirms the effectiveness of the proposed frequency-modulation scheme. The proposed analog translinear circuit allows custom integrated circuit implementation, making it a viable low-cost solution to the elimination of line-current harmonics in switching regulators     

Sensitivity tradeoffs for multivariable plants

This paper gives a characterization of the smallest upper bound on the norm of the sensitivity matrix over a frequency interval, with the constraint that the norm remain bounded at all frequencies. The matrix Nevanlinna-Pick interpolation theory is applied to give a necessary and sufficient condition for the existence of a sensitivity matrix meeting the upper bound conditions on thejomega-axis, and the matrix Nevnnlinna-Pick algorithm is used to compute the bounds. A scalar example is also presented to demonstrate the tradeoffs between the bounds inside and outside a given operating frequency band.     

Significance test or effect size?

I describe and question the argument that in psychological research, the significance test should be replaced (or, at least, supplemented) by a more informative index (viz., effect size or statistical power) in the case of theory-corroboration experimentation because it has been made on the basis of some debatable assumptions about the rationale of scientific investigation. The rationale of theory-corroboration experimentation requires nothing more than a binary decision about the relation between two variables. This binary decision supplies the minor premise for the syllogism implicated when a theory is being tested. Some metatheoretical considerations reveal that the magnitude of the effect-size estimate is not a satisfactory alternative to the significance test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluating technical education in a spatially and temporallycompressed world

Engineering and technology educators face potential limitations and problems should they neglect the diversity of social, cultural and political environments in which their students find themselves despite the apparent compression of time and space brought about by technological changes that the difference between individuals is getting smaller. This article looks at the evaluation of engineering and technology education from a social and cultural viewpoint and suggests that the evaluation should aim to be sensitive to local traditions and histories, and to particular wants, needs and fancies     

Adaptive joint beamforming and B‐MMSE detection for CDMA signal reception under multipath interference

The combination of antenna array beamforming with multiuser detection can effectively improve the detection efficiency of a wireless system under multipath interference, especially in a fast‐fading channel. This paper studies the performance of an adaptive beamformer incorporated with a block‐wise minimum mean square error(B‐MMSE) detector, which works on a unique signal frame characterized by training sequence preamble and data blocks segmented by zero‐bits. Both beam‐former weights updating and B‐MMSE detection are carried out by either least mean square (LMS) or recursive least square (RLS) algorithm. The comparison of the two adaptive algorithms applied to both beamformer and B‐MMSE detector will be made in terms of convergence behaviour and estimation mean square error. Various multipath patterns are considered to test the receiver's responding rapidity to changing multipath interference. The performance of the adaptive B‐MMSE detector is also compared with that of non‐adaptive version (i.e. through direct matrix inversion). The final performance in error probability simulation reveals that the RLS/B‐MMSE scheme outperforms non‐adaptive B‐MMSE by 1–5 dB, depending on the multipath channel delay profiles of concern. The obtained results also suggest that adaptive beamformer should use RLS algorithm for its fast and robust convergence property; while the B‐MMSE filter can choose either LMS or RLS algorithm depending on antenna array size, multipath severity and implementation complexity. Copyright © 2004 John Wiley & Sons, Ltd.     

基于HBP编码结构的MVC快速算法

针对MVC系统中运算量最大的矢量预测部分——单向搜索和双向搜索,该文提出一种快速算法。根据多视点视频的序列相关性,采用立体-运动约束模型在运动域和视差域进行联合迭代单向搜索,设计可信度因子来自适应地调整修正搜索窗口,同步搜索得到运动和视差矢量。此外,通过分析双向预测宏块的特性,提出一种双向搜索提前中止算法。实验结果证明该文算法的有效性,能在保持编码质量的同时极大减少算法复杂度。