Evolution of Scour Depth at Circular Bridge Piers

Experiments of bridge pier scour are carried out under steady and unsteady clear-water scour conditions with uniform and nonuniform sediments. Around the pier nose, the sediment size variation of surface bed materials is investigated, and a regressed formula is obtained for estimating the mixing layer thickness in terms of median sediment size and geometric standard deviation of grain size distribution. A method based on the mixing layer concept is developed for calculating the equilibrium scour depth in nonuniform sediment. Based on the experimental data of scour rate, a model simulating the scour-depth evolution under steady flow in nonuniform sediment is presented. By analyzing experimental data, a scheme is proposed for computing the scour-depth evolution under unsteady flow.     

Cross-Layer Communication With an Optical Packet Switched Network via a Message Injection Control Interface

Message injection control and queue management for an optical packet switched network is demonstrated via interoperation of a network with an optical interface buffer. In a time-slotted manner, cross-layer signaling is employed between the input buffer and network to dynamically reroute dropped payload packets with multiple wavelength-striped 10-Gb/s channels. At the output of the network, error-free transmission with bit-error-rates less than were confirmed, with an introduced power penalty of 3.5 dB.     

The formation of well-oriented dense ZnO film using MOCVD

For utilization of ZnO in optoelectronics, the large-area heteroepitaxy of ZnO is needed. However the lattice mismatch and anisotropy of ZnO prevent the successful heteroepitaxy of ZnO film through the conventional slow growth approach. This paper demonstrates an unconventional approach of dense ZnO film formation by high growth rate deposition using metal-organic chemical vapor deposition. The mechanism of the formation of well-oriented and dense ZnO film with large grains is illustrated in terms of dimethylzinc flow rate, oxygen flow rate, and VI/II ratio.     

A frizzled homolog functions in a vertebrate Wnt signaling pathway

BACKGROUND: Wnts are secreted proteins implicated in cell-cell interactions during embryogenesis and tumorigenesis, but receptors involved in transducing Wnt signals have not yet been definitively identified. Members of a large family of putative transmembrane receptors homologous to the frizzled protein in Drosophila have been identified recently in both vertebrates and invertebrates, raising the question of whether they are involved in transducing signals for any known signaling factors. RESULTS: To test the potential involvement of frizzled homologs in Wnt signaling, we examined the effects of overexpressing rat frizzled-1 (Rfz-1) on the subcellular distribution of Wnts and of dishevelled, a cytoplasmic component of the Wnt signalling pathway. We demonstrate that ectopic expression of Rfz-1 recruits the dishevelled proten-as well as Xenopus Wnt-8 (Xwnt-8), but not the functionally distinct Xwnt-5A-to the plasma membrane. Moreover, Rfz-1 is sufficient to induce the expression of two Xwnt-8-responsive genes, siamois and Xnr-3, in Xenopus explants in a manner which is antagonized by glycogen synthase kinase-3, which also antagonizes Wnt signaling. When Rfz-1 and Xwnt-8 are expressed together in this assay, we observe greater induction of these genes, indicating that Rfz-1 can synergize with a Wnt. CONCLUSIONS: The results demonstrate that a vertebrate frizzled homolog is involved in Wnt signaling in a manner which discriminates between functionally distinct Wnts, which involves translocation of the dishevelled protein to the plasma membrane, and which works in a synergistic manner with Wnts to induce gene expression. These data support the likely function of frizzled homologs as Wnt receptors, or as components of a receptor complex.     

基于支撑树的光网络保护容量配置算法

本文提出了一种新的保护容量配置算法.该方法基于网络的支撑树概念,在支撑树树干和部分连枝上保留网络容量,保证网络上任何两个节点之间都有至少两条不同路由,为单一链路或节点故障提供良好的保护能力.     

An Axial-Flux Permanent-Magnet Synchronous Generator for a Direct-Coupled Wind-Turbine System

This paper presents a unique axial-flux permanent-magnet synchronous generator (AFPMSG), which is suitable for both vertical-axis and horizontal-axis wind turbine generation systems. An outer-rotor design facilitates direct coupling of the generator to the wind turbine, while a coreless armature eliminates the magnetic pull between the stationary and moving parts. The design and construction features of the AFPMSG are reviewed. The flux-density distribution is studied, with the aid of a finite element software package, in order to predict the generated e.m.f. waveform. The performance equations of the AFPMSG are derived, and the condition for maximum efficiency is deduced, for both constant-speed and variable-speed operations. The experimental results, in general, confirm the theory developed     

Immediate argon laser peripheral iridoplasty as treatment for acute attack of primary angle-closure glaucoma: a preliminary study

OBJECTIVE: This study aimed to examine the intraocular pressure (IOP)-lowering effects and safety of immediate argon laser peripheral iridoplasty (ALPI) as a first-line treatment for acute primary angle-closure glaucoma (PACG). DESIGN: A prospective cohort study. PARTICIPANTS: Ten consecutive patients with their first attack of PACG, with IOP of 40 mmHg or greater, were recruited into the study. INTERVENTION: On presentation, each patient received topical pilocarpine (4%) and timolol (0.5%) and immediate ALPI as primary treatment. The IOPs at 15, 30, and 60 minutes after ALPI were documented by applanation tonometry. When the corneal edema had settled, laser peripheral iridotomy was performed as a definitive treatment. MAIN OUTCOME MEASURES: The IOP, corneal edema, and complications from ALPI were measured. RESULTS: The mean IOP of this group of patients was reduced from 59.5+/-10.4 mmHg to 28.7+/-14.9 mmHg at 15 minutes, 21.7+/-13.1 mmHg at 30 minutes, and 16.0+/-9.4 mmHg at 60 minutes after ALPI. No complications from the laser procedure were encountered during the study period. In nine of the ten patients, the corneal edema cleared up 1 hour after ALPI. In the remaining patient, the cornea cleared up 2 hours after ALPI. CONCLUSION: From this preliminary study, immediate ALPI, without adjunctive systemic antiglaucoma treatment, appeared to be very effective in controlling the IOP and returning corneal clarity in acute PACG. Its safety also appeared reassuring and did not have the risks associated with conventional systemic therapies.     

Design for geometric parameters of PEM fuel cell by integrating computational fluid dynamics code with optimization method

The present study is aimed at optimization of the geometric parameters of the proton exchange membrane (PEM) fuel cells through numerical simulation. The approach is developed by integrating a direct problem solver with an optimizer. A commercial computational fluid dynamics code is used as the direct problem solver, which is used to simulate the three-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC. On the other hand, the simplified conjugate-gradient method (SCGM) is employed to build the optimizer, which is combined with the direct problem solver in order to seek the optimal geometric parameters, including, for example, the gas channel width fraction, the gas channel height and the thickness of the gas diffusion layer. It is found that the present approach can be applied to determine the optimal set of geometric parameters, and the search process is robust and always leads to a unique final solution regardless of the initial guess.     

A 0.26-μm2 U-Shaped Nitride-Based Programming Cell on Pure 90-nm CMOS Technology

A novel one time programming (OTP) cell with a nitride-based storage has been developed for advanced programmable logic applications. This cell that is processed by pure logic process and decoupled with transistor gate oxide has a highly stable and extremely wide on/ off window. It exhibits a superior disturb immunity in program and read operations. In addition, a very small cell size (0.263 mum² ) has been achieved using 90-nm pure CMOS logic process and is scalable in more advanced CMOS logic technologies by eliminating the constraint of transistor gate-oxide thickness. The all new OTP cell has a wide ON/OFF window and a superior writing efficiency by source-side injection programming mechanism. This novel OTP cell is a very promising programmable logic solution, with a fully CMOS-logic-compatible process below the 90-nm node.