PCI Express普及化超乎想象

PCI Express(PCIe)是目前最新的高速串行连接技术之一,短期内将无所不在.由于它继承了全球相当普遍的PCI数据总线,因此这项技术具有快速带动PC及外围配备市场的威力和重大意义,因而受到相当大的重视.因各式各样的需求所致,PCIe足迹已遍布各种应用系统和市场中,未来还会出现在哪些应用上呢?本文将与您共同探讨一二.     

DPSK versus pilot-aided PSK MAP equalization for fast-fadingchannels

This letter compares pilot-aided phase-shift keyed (PSK) and differential PSK (DPSK) modulation when using new maximum a posteriori joint channel estimation and equalization receivers with frequency-selective fast-fading channels. We conclude that pilot-aided PSK has superior bit-error rate performance in this case. However, at low signal-to-noise ratio, performance is similar, and DPSK is competitive due to reduced receiver complexity     

The Performance of the Adaptive Aggregation Mechanism (AAM) Under Mixed Traffic Loads

The adaptive packet aggregation algorithm (AAM) has been shown to have a superior performance over the first-in first-out (FIFO) algorithm in terms of the throughput and delay (Deng and Davis in International conference on wireless communications and signal processing 2013 (WCSP2013), Hangzhou, China, pp 449–504, 2013; 20th IEEE symposium on communications and vehicular technology in the Benelux 2013 (IEEE SCVT 2013), Namur, 2013). In this paper, we will show that when compared with the FIFO and smallest-size first-served algorithms, the AAM algorithm has the best performances in terms of the trade-off between the overhead saving and the average delay under mixed traffic loads in wireless LANs. The simulation results show that the AAM algorithm produces the largest average aggregate packet size.     

Low-crosstalk code-division multiplexed interferometric array

The results obtained using code-division multiplexing with an array of eight sensors are reported. It is demonstrated that crosstalk levels approximately -60 dB can be achieved using this approach using return-to-zero pulse coding.<>     

Construction of baselines for VoIP traffic management on open MANs

In the last century, owing to the constant evolution of technologies telecommunication networks have become increasingly robust, being able to support multiple services. These services are part of the heterogeneous network traffic that can be carried through the Internet. Many of these services, including VoIP, are latency sensitive. In other words, this means that their quality depends directly on the network quality of service. Since users tend to become more sensitive with the instability and unavailability of the network, it is important to improve traffic management. A particular type of data that could be used to improve VoIP traffic management is the Internet Protocol Detail Record (IPDR). IPDRs are tickets created by all VoIP call attempts which contain a group of information related to the call history. Because of its full range of information, IPDRs can be used to create VoIP traffic baselines. This paper presents the development of baselines based on IPDRs to support VoIP traffic management in open‐access Metropolitan Area Networks (MAN). Copyright © 2013 John Wiley & Sons, Ltd.     

Plasma Concentration and Lipid Composition of Lipoproteins in Lactating Dairy Cows Fed Control and High Grain Diets

Six multiparous Holstein cows ranging from 7 to 19 wk postpartum were in a switchback design to determine effects of feeding high grain diets on lipoprotein concentration and composition in blood. Percents concentrate, alfalfa haylage, and corn silage of control and high grain diets were 50, 83; 25, 9; and 25, 8 dry matter. Milk yield (kg/day), milk fat percentage, and fat yield (g/day) averaged 27.7, 3.58, 997 and 30.2, 2.45, 729 for control and high grain treatments. Very low density, low density, and high density lipoproteins were isolated by gel filtration of total lipoproteins obtained by ultracentrifugation. Lipoprotein concentrations in blood plasma of cows fed the control or high grain diets were similar. Triglyceride, phospholipid, cholesterol, and cholesterol ester contents of each lipoprotein class were not altered by treatment. High grain feeding increased octadecadienoic fatty acid content of low density and high density lipoprotein cholesterol esters and decreased octadecenoic and octadecatrienoic acids. The trend was similar for the very low density lipoprotein fraction. Phospholipid octadecenoic acid decreased in all lipoprotein fractions but only significantly for high density lipoproteins. It is unlikely that differences in lipid composition of plasma lipoproteins caused alterations in lipoprotein metabolism leading to fat depression in this and other similar studies.     

Antenna design strategy and demonstration for software-defined radio (SDR)

Antennas are a key enabling technology for software-defined radio (SDR). Although software is extremely flexible, SDR??s potential is limited by antenna size and performance. In this paper, we review typical antenna miniaturization techniques and fundamental theories that limit antenna size and performance including operational bandwidth, gain (or range), and radiation pattern. Possible antenna design strategies are discussed to meet the desired specifications in SDR based on observations from the limit theories. The application of strategies to enable multiband (resonant), continuous multiband (frequency independent), and instantaneous, ultra-wideband antennas are discussed qualitatively. Advantages, disadvantages, and design trade-off strategies for different types of antennas are compared from a system-level perspective. A design example for a compact ultra-wideband (UWB) antenna is presented for a software-defined platform. The example involves a direct-conversion radio developed in Wireless@VT that uses a Motorola RFIC having a 100 MHz?C6 GHz operational frequency range with a 9 kHz?C20 MHz channel bandwidth. The example antenna covers frequencies from 450 MHz to 6 GHz instantaneously with approximately 5-dBi realized gain over a finite-size ground plane, including return loss and omni-directional coverage.     

Revisiting the Worksite in Worksite Health Campaigns: Evidence From a Multisite Organ Donation Campaign

This article advances the beginnings of a general theory of organizational features to aid in understanding why health campaigns that work well in one organization may be ineffectual in another organization. The physical, social, and information structures of organizations are theorized to create an interaction environment that is distinct to each organization and that influences health campaigns. To test this argument, an organ donation campaign was conducted in 46 organizations. Multilevel modeling yielded mixed findings. Physical structure was negatively associated with signing an organ donor card. Social structure and information structure were positively associated with communication with coworkers about donation and communicative peer influence. Industry type was positively associated with knowledge change.     

Temperature compensation of total power radiometers

This paper describes a new technique to compensate output variations of total power radiometers due to physical temperature changes of the instrument. This technique performs the correction without the addition of expensive microwave hardware required in Dicke switching or many other widely used methods. A characterization period, over which the input antenna temperature is known, indicates the appropriate output adjustment needed for a change in physical temperature of the radiometer. The method effectively corrects the output in an example radiometer system built with inexpensive commercially available parts. For a 30-K variation in physical temperature, the measured data shows an improvement from 60-K peak-to-peak error to 6.9 K with an average absolute error of 1.1 K.     

Tone interference in VSAT spectrum

This paper investigates the problem of tone interference within the very small aperture terminal (VSAT) binary phase-shift keying (BPSK) signal spectrum. The degree of performance degradation of a VSAT link in the presence of a tone interference is discussed. A simple theoretical analysis is derived, and its validity is verified by experimental measurements performed using a standard commercial VSAT modem measurement setup