亚太地区卫星正在启用新型业务

对于直接到户(DTH)业务的提供商和其它企业家来说,亚太地区存在着新的机会:高清晰度电视(HDTV)慢慢地进入了这一地区,蜂窝电话回传、因特网协议(IP)宽带和企业领域应用正在加速。所有这些让人明白,亚太地区的各种商业机会将在未来数年里稳步增长。泰国Shin卫星公司新宽带卫星iP     

光伏产业调整LED将席卷笔记本PC

全球对于太阳能的旺盛需求已导致用于生产太阳能电池的多晶硅出现严重短缺,促使光伏（PV）太阳能电池供应商调整业务结构和策略,以及寻找可替代的原材料。     

SMOS Calibration

The calibration of the Soil Moisture and Ocean Salinity (SMOS) payload instrument, known as Microwave Imaging Radiometer by Aperture Synthesis (MIRAS), is based on characterization measurements which are performed initially on-ground prior to launch and, subsequently, in-flight. A good calibration is a prerequisite to ensure the quality of the geophysical data. The calibration scheme encompasses both the spaceborne instrument and the ground data processing. Once the system has been calibrated, the instrument performance can be verified, and the higher level geophysical variables, soil moisture and ocean salinity, can be validated. In this paper, the overall calibration approach is presented, focusing on the main aspects relevant to the SMOS instrument design and mission requirements. The distributed instrument, comprising 72 receivers, leads to a distributed internal calibration approach supported by specific external calibration measurements. The relationship between the calibration data and the routine ground processing is summarized, demonstrating the inherent link between them. Finally, the approach to the in-flight commissioning activities is discussed.     

Effect of Al Composition and Gate Recess on Power Performance of AlGaN/GaN High-Electron Mobility Transistors

AlGaN/GaN high-electron mobility transistors with different Al compositions and barrier thicknesses were compared. The samples with higher Al composition and similar 2D electron gas density showed higher gate leakage, utilizing a slant field plate gate process. By applying a gate recess etch and a slant field plate gate process, gate leakage was improved to a similar level for all the devices, and the power density and PAE were much improved.     

Preservation of refrigerated meats with controlled atmospheres: Treatment and post-treatment effects of carbon dioxide on pork and beef

Whole pork loins were divided into roasts and subjected to air control and carbon dioxide enriched atmospheres at 1°C for up to 21 days. Quintuplicate samples of both control and carbon dioxide treated loins were transferred to air storage at 0,4,7, 14 and 21 days and further held for 0, 3(4), 7 and 10 days at 4°C. Microbiological counts were taken at all time permutations. The results indicated a strong inhibiting effect of the carbon dioxide atmosphere on microbial growth as well as a marked residual effect during post-treatment storage in air. Satisfactory colour and odour were maintained on the loins for extended storage times, with visual and olfactory deterioration preceding microbial spoilage. Beef round wedges were treated in a similar manner. Although bacterial spoilage inhibition was comparable, colour degeneration was rapid and severe, making the method unsuitable for treatment of finished beef cuts.     

PROPOSALS FOR THE EFFICIENT AND ECONOMICAL USE OF HOPS IN BREWING

The hop lupulin glands, which contain the essential oils and resin acids, can be separated effectively from the bulky and worthless bracts and residues in a mechanical process which avoids solvent contamination. The separation is accomplished in an air stream through a centrifugal sifter after the lupulin has been rubbed off in a disc pin mill. The separated lupulin can be broken open by grinding in a colloid mill and used to obtain a dry hop aroma in beers by an ‘instant’ process. The lupulin can be used to bitter beers either directly in the copper or in a pre-boiling process. It can also be used in an aqueous extraction process to yield, nearly quantatively, pure and separate extracts of the α- and β-acids. The α-acids can then be isomerized almost quantitatively and the β-acids can be oxidized to give a 50% yield of hulupones. The hop residues, when boiled with wort, give an approximately 50% utilization of the remaining α-acids. These isohumulones can then be enhanced by those obtained from the extracted α-acids and the bitterness can be supplemented by the hulupones obtained from the β-acids. Overall, this process is calculated to give a bitterness utilization equivalent to 87% calculated on the original α-acids.     

Multiuser Detection for Out-of-Cell Cochannel Interference Mitigation in the IS–95 Downlink

This paper considers the application of multiuser detection techniques to improve the quality of downlink reception in a multi-cell IS–95 digital cellular communication system. In order to understand the relative performance of suboptimum multiuser detectors including the matched filter detector, optimum multiuser detection in the context of the IS–95 downlink is first considered. A reduced complexity optimum detector that takes advantage of the structural properties of the IS–95 downlink and exhibits exponentially lower complexity than the brute-force optimum detector is developed. The Group Parallel Interference Cancellation (GPIC) detector, a suboptimum, low-complexity multiuser detector that also exploits the structure of the IS–95 downlink is then developed. Simulation evidence is presented that suggests that the performance of the GPIC detector may be near-optimum in several cases. The GPIC detector is also tested on a snapshot of on-air data measured with an omnidirectional antenna in an active IS–95 system and is shown to be effective for extracting weak downlink transmissions from strong out-of-cell cochannel interference. The results of this paper suggest that the GPIC detector offers the most performance gain in scenarios where weak downlink signals are corrupted by strong out-of-cell cochannel interference.     

Identification of periodic signals with uncertain frequency

This paper presents a new algorithm to identify periodic signals with uncertain frequency. The approach is based on the behavior of an internal model in an error feedback system. As such, the signal is fed to a fictitious plant with a feedback controller. The feedback controller is based on a traditional controller in parallel with an internal model which identifies and cancels the periodic disturbances. Under ideal circumstances, the phase plot of the states of the internal model form an ellipse. The speed of rotation about this ellipse can be used to calculate the difference between the nominal frequency of the model and the true frequency of the periodic signal. An integral controller or a least-squares estimator can be used to drive this error to zero. Simulations demonstrate the validity of this approach with time-varying frequency, and the algorithm is then applied to some data collected from a spot welder that has been corrupted by a sinusoidal signal whose frequency is between 1 Hz and 5 KHz.     

Methodology for Small-Signal Model Extraction of AlGaN HEMTs

Both large- and small-periphery AlGaN high- electron mobility transistors (HEMTs) will find applications in microwave systems from 2 to 40 GHz because of their superior power handling capability. A self-consistent approach is presented for the linear model's parameter extraction from measured S-parameters. The model for parasitics is selected to reflect loading from both the probe pads and the interconnect regions, including the air bridges. The objective is to accurately extract intrinsic model parameters as the device periphery is increased from 50 mum to 1 mm and to isolate the effects of device layouts, including air bridging the source regions. To accurately extract the shunt and series parasitics, the device must be represented in its ON- and OFF-states determined by the gate and drain bias. The intrinsic device capacitances are not negligible in the forward and beyond-pinchoff reverse bias states at zero drain bias and must be accounted for. With these corrections to the measured S-parameters, consistent results for the intrinsic device parameters are obtained with both small- and large-periphery AlGaN HEMTs.     

Comparative analysis of the outdoor performance of a dye solar cell mini‐panel for building integrated photovoltaics applications

New generation photovoltaic (PV) devices such as polymer and dye sensitized solar cells (DSC) have now reached a more mature stage of development, and among their various applications, building integrated PVs seems to have the most promising future, especially for DSC devices. This new generation technology has attracted an increasing interest because of its low cost due to the use of cheap printable materials and simple manufacturing techniques, easy production, and relatively high efficiency. As for the more consolidated PV technologies, DSCs need to be tested in real operating conditions and their performance compared with other PV technologies to put into evidence the real potential. This work presents the results of a 3 months outdoor monitoring activity performed on a DSC mini‐panel made by the Dyepower Consortium, positioned on a south oriented vertical plane together with a double junction amorphous silicon (a‐Si) device and a multi‐crystalline silicon (m‐Si) device at the ESTER station of the University of Rome Tor Vergata. Good performance of the DSC mini‐panel has been observed for this particular configuration, where the DSC energy production compares favorably with that of a‐Si and m‐Si especially at high solar angles of incidence confirming the suitability of this technology for the integration into building facades. This assumption is confirmed by the energy produced per nominal watt‐peak for the duration of the measurement campaign by the DSC that is 12% higher than that by a‐Si and only 3% lower than that by m‐Si for these operating conditions. Copyright © 2013 John Wiley & Sons, Ltd.