10GBASE-T:基于铜质电缆的10Gb以太网指南

10GBASE-T面临着回波、近端串扰、远端串扰、Alien串扰等信道损耗带来的挑战。10Gb以太网切实可行且万事俱备自从2002年批准10Gb以太网通信标准以来,业界总是预测"明年"将会最终推出10Gb以太网。然而,自诞生以来,10Gb以太网的发展就因为其无法利用各种低速以太网标准成熟的传输方式而受到阻碍。     

Some aspects of the biology of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), a pest of stored groundnuts in Nigeria

The biology of Plodia interpunctella (Hübner) was studied at various combinations of temperature and relative humidity. The incubation period of eggs ranged from 4 to 7 days. Development from laying of egg to adult lasted an average of 50.9 days at 25°C and 60% r.h. and 34.6 days at 30°C and 80% r.h. At 70 and 80% relative humidity, development was faster, more progeny were produced and the moths were heavier than at 60% r.h. Relative humidity had little effect on egg and pupal development.The larvae were negatively phototactic. However, the rate of development of the strain studied was similar in constant darkness, constant light or in a 12 hr-light: 12 hr-dark light system. The adult moths were immobile in diffused daylight. Locomotory activity was markedly high at dusk and was accompanied by an increase in the rate of pairing. Temperatures between 27 and 31°C did not appear to influence locomotory activity.Cracked groundnuts were more favourable for development than whole nuts which were in turn better than groundnut meal. The weight losses inflicted on infested groundnuts were directly correlated with the total weights of emerged moths and differed according to the treatment given to the medium. Losses in weight of about 8.7 and 8.6% were observed when 13 larvae completed development in 30 g of whole nuts and cracked nuts, respectively. Females consumed more food and were heavier than the males. Each larva ate an average of 140 mg of whole nuts and 190 mg of cracked groundnuts to complete development. The increases in free fatty acid values were not appreciably higher in infested media than in the control. Increases of 17.5 and 18.2 m-equiv of peroxides were observed in infested whole and cracked nuts, respectively.     

Evaluation of Brassica species as leaf sources for extending the processing season of a leaf protein concentrate plant

Leaf protein concentrates (LPC) were prepared in large pilot plant equipment from seven Brassica varieties grown on plots of up to 0.06 ha. Plants were harvested about a month before and after the lucerne processing season. Best yields of LPC, from leafier or forage-type species, were up to 0.9 t ha^?1. Properties were as good as or better than those of LPC from lucerne. Lucerne processing procedures were modified to maximize yields from the more succulent Brassica plants.     

Scheduling Combined Unicast and Multicast Traffic in Broadcast WDM Networks

This paper studies the performance of various strategies for scheduling a combined load of unicast and multicast traffic in a broadcast WDM network. The performance measure of interest is schedule length, which directly affects both aggregate network throughput and average packet delay. Three different scheduling strategies are presented, namely: separate scheduling of unicast and multicast traffic, treating multicast traffic as a number of unicast messages, and treating unicast traffic as multicasts of size one. A lower bound on the schedule length for each strategy is first obtained. Subsequently, the strategies are compared against each other using extensive simulation experiments in order to establish the regions of operation, in terms of a number of relevant system parameters, for which each strategy performs best. Our main conclusions are as follows. Multicast traffic can be treated as unicast traffic, by replicating all multicast packets, under very limited circumstances. On the other hand, treating unicast traffic as a special case of multicast traffic with a group of size 1, produces short schedules in most cases. Alternatively, scheduling and transmitting each traffic component separately is also a good choice.     

A Comparison of Allocation Policies in Wavelength Routing Networks*

We consider wavelength routing networks with and without wavelength converters, and several wavelength allocation policies. Through numerical and simulation results we obtain upper and lower bounds on the blocking probabilities for two wavelength allocation policies that are most likely to be used in practice, namely, most-used and first-fit allocation. These bounds are the blocking probabilities obtained by the random wavelength allocation policy with either no converters or with converters at all nodes of the network. Furthermore, we demonstrate that using the most-used or first-fit policies gives an improvement on call blocking probabilities that is equivalent to employing converters at a number of nodes in a network with the random allocation policy. These results have been obtained for a wide range of loads for both single-path and general mesh topology networks. The main conclusion of our work is that the gains obtained by employing specialized and expensive hardware (namely, wavelength converters) can be realized cost-effectively by making more intelligent choices in software (namely, the wavelength allocation policy).     

挑战测试的极限

Teradyne公司主席兼CEO George Chamillard先生最近接受我刊结盟出版物Electronic News的专访,话题主要集中在测试市场充满痛苦的复苏以及未来的市场机遇.下面则是这次访谈的节录.     

Direct Writing of Gallium‐Indium Alloy for Stretchable Electronics

In this paper, a direct writing method for gallium‐indium alloys is presented. The relationships between nozzle inner diameter, standoff distance, flow rate, and the resulting trace geometry are demonstrated. The interaction between the gallium oxide layer and the substrate is critically important in understanding the printing behavior of the liquid metal. The difference between receding and advancing contact angles demonstrates that the adhesion of the oxide layer to the substrate surface is stronger than the wetting of the surface by the gallium‐indium alloy. This further demonstrates why free‐standing structures such as the traces described herein can be realized. In addition to the basic characterization of the direct writing process, a design algorithm that is generalizable to a range of trace geometries is developed. This method is applied to the fabrication of an elastomer‐encapsulated strain gauge that displays an approximately linear behavior through 50% strain with a gauge factor of 1.5.     

The multimedia broadcast/multicast service

This article provides an overview of the multimedia broadcast/multicast service (MBMS) for universal mobile telecommunications system (UMTS) networks. We first outline the features of UMTS networks as defined by the 3rd generation partnership project (3GPP) in order to provide a background for the discussion to follow. We then present the overall MBMS architecture, the services that it provides to the users and the differences between the broadcast and multicast options. The implementation details of MBMS are explained in terms of the modifications needed to the network, the new signaling procedures required and the impact of MBMS on the radio part of the network. We then describe how the security architecture of UMTS is used to support content protection and key distribution for MBMS groups. We evaluate the prospects of MBMS by comparing it first with IP multicast and then with DVB‐H, considered by many to be the closest competitor of MBMS. Finally, we conclude with a discussion of the technical and business challenges still faced by MBMS. Copyright © 2006 John Wiley & Sons, Ltd.