Prebooking reservation mechanism for next-generation optical networks

In future wavelength-division multiplexed networks, wavelength resources are efficiently utilized by statistical multiplexing and dynamic lightpath provisioning. In order to provide desired blocking probability and the ease of quality of service provisioning, this paper concentrates on the end-to-end connection acknowledged optical burst switching (OBS) protocols, and proposes a prebooking mechanism to improve the lightpath bandwidth efficiency, which consequently, reduces the blocking probability and better supports latency-sensitive traffic. The prebooking mechanism excludes lightpath acknowledgement delay from the lightpath holding time by "prebooking" each aggregated burst/flow based on the estimated characteristics of arriving traffic. More specifically, a burst length prediction and reservation strategy is proposed and analyzed for the widely observed self-similar incoming traffic. The simulation results show that the proposed excessive reservation strategy is able to achieve low bit loss caused by the prediction error. In addition, the proposed mechanism is also investigated with constant bit rate traffic in a large mesh backbone, such as NSFNET. The results demonstrate that in large networks, the proposed prebooking mechanism is able to bring significant benefits in terms of blocking probability and lightpath bandwidth efficiency. For example, with a maximum acceptable end-to-end delay of 90 ms and a 10/sup -4/ bit loss tolerance, our prebooking mechanism yields approximately double the supported traffic load relative to the familiar wavelength-routed OBS architecture.     

基于沃尔什函数的最小二乘动态建模方法及应用

本文研究了一种基于沃尔什函数的最小二乘传感器动态建模方法，并详细讨论了其实现步骤。这种方法以传感器时域动态校准数据为基础，可以直接得出传感器对应的微分方程或连续传递函数的系数。通过对仿真数据的辨识建模，证明了其有效性，并采用此方法对一种力传感器的脉冲响应曲线进行了实际的建模研究。     

Regulation of classic and alternative bile acid synthesis in hypercholesterolemic rabbits: effects of cholesterol feeding and bile acid depletion

The effect of cholesterol feeding (3 g/day) on bile acid synthesis was examined in 10 New Zealand white rabbits (NZW), 8 Watanabe heterozygous and 10 homozygous rabbits with partial and complete deficiencies of LDL receptors. After 10 days of cholesterol feeding, bile fistulas were constructed and bile acid pool sizes were measured. Cholesterol feeding increased plasma and hepatic cholesterol levels in all rabbit groups. Baseline bile acid pool sizes were smaller (P < 0.01) in heterozygotes (139 +/- 3 mg) and homozygotes (124 +/- 30 mg) than NZW rabbits (254 +/- 44 mg). After feeding cholesterol, bile acid pool sizes doubled with increased cholic acid synthesis in NZW and, to a lesser extent, in Watanabe heterozygous rabbits but not in homozygotes. Baseline cholesterol 7alpha-hydroxylase activity in NZW and heterozygotes declined 69% and 53% (P < 0.001), respectively, after cholesterol feeding. Sterol 27-hydroxylase activity reflecting alternative bile acid synthesis increased 66% (P < 0.01) in NZW and 37% in Watanabe heterozygotes but not in homozygotes after feeding cholesterol. Bile fistula drainage stimulated cholesterol 7alpha-hydroxylase activity but not sterol 27-hydroxylase activity in all three rabbit groups. These results demonstrated that dietary cholesterol increased hepatic sterol 27-hydroxylase activity and alternative bile acid synthesis to expand the bile acid pool and inhibited cholesterol 7alpha-hydroxylase in NZW and in Watanabe heterozygous rabbits but not in homozygotes with absent hepatic LDL receptor function. Thus, in rabbits, sterol 27-hydroxylase is up-regulated by the increased hepatic cholesterol that enters the liver via LDL receptors whereas cholesterol 7alpha-hydroxylase is controlled by the circulating hepatic bile acid flux.     

Backscattering enhancement and clustering effects of randomlydistributed dielectric cylinders overlying a dielectric half space basedon Monte-Carlo simulations

Backscattering enhancement can exist in volume-surface interactions where a double bounce can arise from one volume scattering and one surface scattering. An important quantity to be determined in backscattering enhancement is the angular width. The authors study backscattering enhancement of the volume-surface interaction by performing Monte-Carlo simulations of scattering by vertical dielectric cylinders overlying a dielectric half space using the Foldy-Lax multiple-scattering equations. The results indicate that the angular width of backscattering enhancement for a scattering layer with a small optical thickness is of the order of the wavelength divided by the layer thickness giving an appreciable angular width of the order of 10-30 degrees that can be important for remote sensing applications. The effects of clustering of scatterers leading to collective scattering and absorption effects are also studied     

The effect of minimum luminal nutrition on mucosal cellularity and immunity of the gut

Many catabolic patients can only consume small volumes of enteral nutrients. The aim of this study was to evaluate markers of cellularity and immunity in the small intestine of rats randomized to receive 6 days of parenteral nutrition, 25% enteral and 75% parenteral nutrition (i.e. minimum luminal nutrition) or enteral nutrition. The same glutamine-enriched solution was used for both parenteral and enteral nutrition. Enteral nutrition was associated with the least amount of jejunal atrophy (P<0.01), with the results from the minimum luminal nutrition group approximating those of the parenteral nutrition group. Parenteral nutrition was associated with the greatest number of CD2+ cells (P< 0.05) and the lowest CD4/CD8 cell ratio (P< 0.01) in the jejunal mucosa. In essence, we failed to demonstrate that there are any appreciable benefits associated with the enteral consumption of 25% of a nutrient load.     

Compensation Scheme of Position Angle Errors of Permanent-Magnet Linear Motors

The position angle is very important in the current control of permanent-magnet linear motors (PMLMs), and its error affects the control precision of currents. However, the position angle is often not accurately detected because of faults in motor making, pulse loss of linear encoders, and so on. In order to precisely control the currents of PMLMs, a compensation scheme of position angle errors is proposed based on the mathematical relation between position angle errors and currents. In the scheme, a position angle error compensator is designed to compensate the position angles detected by linear encoders. Furthermore, a filter and a class of iteration learning algorithm are proposed to avoid the errors produced by detected phase currents and phase voltages. Simulation results show that position angle errors of PMLMs are fully compensated. Using the designed position angle error compensator, currents can be controlled in a more precise manner.     

Multi‐phase electro‐chemical catalytic oxidation of wastewater

The removal of organic pollutants from synthetic wash wastewater by a combined multi‐phase electro‐catalytic oxidation method was evaluated using porous graphite as anode and cathode, and CuO–Co₂O₃–PO₄^3? modified kaolin as catalyst. The synergic effect on COD removal was studied when integrating the electro‐chemical reactor with the effective modified kaolin in a single undivided cell; the results showed that higher COD removal efficiency was obtained than those obtained using the individual processes. Under optimal conditions of pH 3, 30 mA cm^?2 current density, very effective reduction of organic pollutants was achieved with this combined electro‐chemical method. High removal efficiency (90%) of the chemical oxygen demand (COD) was obtained in 60 min in the treatment of simulated wash wastewater (anionic surfactant, sodium dodecyl benzene sulfonate [DBS]). This method was also applied to treat wastewater form paper‐making and resulted in a COD reduction of 84%. Based on the investigation, a possible mechanism of this combined electro‐chemical process was proposed. The pollutants in wastewater could be decreased by the high reactive OH? that were produced via the decomposition of electro‐generated H₂O₂ activated by the synergic effect of electro‐field and catalyst. The results indicate that the multi‐phase catalytic electro‐chemical oxidation process is a promising technique for wastewater treatment. Copyright © 2006 Society of Chemical Industry     

Y(C_(16)H_(16)N_2O_2)(NO_3)_3(CH_3SOCH_3)的合成和晶体结构

合成了硝酸钇（Ⅲ）与双希夫碱Ｎ，Ｎ′－二亚水杨基乙二胺、二甲基亚砜的配合物〔Ｙ（Ｃ６Ｈ４ＯＨＣＨＮＣ２Ｈ４ＮＣＨＣ６Ｈ４ＯＨ）（ＮＯ３）３（ＣＨ３ＳＯＣＨ３）〕。ｘ—射线单晶结构分析表明该晶体属单斜晶系、空间群为Ｐ２１／ｎ，ａ＝０．９６３１（２）ｎｍ，ｂ＝１．６４１４（５）ｎｍ，ｃ＝１．６２０９（３）ｎｍ，β＝１０２．９８（２）°，Ｚ＝４，Ｄｘ＝１．６５３Ｍｇ·ｍ－３。Ｙ（Ⅲ）配位数为９，配位几何为畸变的单帽四方反棱柱，所有的配位原子均为氧原子，分别来自三个硝酸根，一个二甲基亚砜和二个双希夫碱，中心离子被双希夫碱桥联，组成一维无限长链。     

CaC2-CaF2还原脱磷的实验研究

分析了不锈钢还脱磷的热力学条件，计算了脱磷率，并在真空感应炉中用CaC2-CaF2熔剂对2Cr13重熔钢液脱磷进行了实验研究。实验结果表明，这种渣有很强的脱氧和脱硫能力。当CaF2和CaC2的质量比接近1：4时，脱磷效果最好，最大脱磷率可达75．3％，并可使最终wp降至0．01％左右。     

Investigations of 3C-SiC inclusions in 4H-SiC epilayers on 4H-SiC single crystal substrates

Synchrotron white beam x-ray topography (SWBXT) and Nomarski optical microscopy (NOM) have been used to characterize 4H-SiC epilayers and to study the character of triangular inclusions therein. 4H-SiC substrates misoriented by a range of angles from (0001), as well as (1 100) and (1120) oriented substrates were used. For epilayers grown on substrates misoriented by 3.5° from (0001) toward <1120>, the triangular inclusions were identified as consisting of two 3C-SiC structural configurations which are related to each other by a 180° rotation about the [111] axis. The epitaxial relationships between the 3C inclusions and the 4H-SiC epilayers (or substrates) were also determined. No evidence was found for the nucleation of 3C-SiC inclusions at superscrew dislocations (along the [0001] axis) in the 4H-SiC substrates. Increasing the off-axis angle of the substrates from 3.5 to 6.5° was found to greatly suppress the formation of the triangular inclusions. In the case of substrates misoriented by 8.0° from (0001) toward <1120>, the triangular inclusions were virtually eliminated. The crystalline quality of 4H-SiC epilayers grown on the substrates misoriented by 8.0° from (0001) was very good. For the (1100) and (1120) samples, there is no indication of 3C-SiC inclusions in the epilayers. Possible formation mechanisms and the morphology of 3C-SiC inclusions are discussed.