Conical beam monopole antenna design for Chinese area positioning system

This article describes the operational principle of the satellite-based Chinese Area Positioning System (CAPS) and proposes a monopole antenna for a large anchored buoy platform in harsh marine environment. The proposed antenna is highly omnidirectional with sufficiently wide half-power beamwidth (HPBW) greater than 40˚ (i.e., not less than ±20° swing) by using a conical ground plane, taking into account the geostationary satellite position, link budget, sea conditions, volume and cost. The impedance bandwidth defined by 10 dB return loss is 750 MHz (5.60-6.35 GHz), and the main lobe direction and the half-power beamwidth are about 46° and 43° at the operating frequency 5.885 GHz, respectively. The antenna prototype has been installed on-site to test its performance in sea. The results confirm that the proposed antenna is a suitable candidate for a variety of CAPS applications in China

Belt Conveyor Dynamic Characteristics and Influential Factors

This paper uses the Kelvin-Voigt viscoelastic model to establish the continuous dynamic equations for tail hammer tension belt conveyors. The viscoelastic continuity equations are solved using the generalized coordinate method. We analyze various factors influencing longitudinal vibration of the belt conveyor by simulation and propose a control strategy to limit the vibration. The proposed approach and control strategy were verified by several experimental researches and cases. The proposed approach provides improved accuracy for dynamic design of belt conveyors

Longitudinal Vibrations of the Viscoelastic Moving Belt

The longitudinal dynamic governing equation of the viscoelastic belt with one end subjected to concentrated mass was established based on the Kelvin-Voigt viscoelastic partial-differential constitutive law. The generalized coordinate method was adopted to solve dynamic displacement and dynamic tension. And then it was reduced to be a nonhomogeneous partial-differential equation where the analytical solutions with a constant acceleration were obtained. The effects of damping coefficient, the loading radio, and the constant acceleration of the belt on the dynamic response of the belt were investigated using the established dynamic model. The results show that the longitudinal vibration frequency of the viscoelastic moving belt increases with an increasing of the mass at the end. The increasing value of the loading radio, damping coefficient, and decreasing the acceleration will lead to a deceasing in dynamic tension. Moreover, the method of solution can be applied to axially moving viscoelastic materials with different boundary conditions

Computers and the academic performance of elementary school-aged girls in China's poor communities

Experts agree that computers and computing play an important role in education. Since the 1980s there has been a debate about gender as it relates to computers and education. However, results regarding gender differences concerning computer use in education are not consistent. In particular there is little work done in China on this issue. Therefore, the overall goal of this paper is to demonstrate whether girls and boys can gain equally from computer-based education in China's elementary schools. To do so we analyze results from three randomized field experiments of a Computer Assisted Learning (CAL) program and One Laptop Per Child (OLPC) program. The field experiments are carried out in three kinds of schools: Shannxi rural public schools: Qinghai minority public schools; and Beijing migrant schools. Although CAL and OLPC have been considered cost effective means to improve learning outcomes, it is not known whether the programs impact girls differently than boys. Our analysis shows that, in fact, there were no differences between female and male students in either the improvement in standardized math test scores or Chinese test scores with either the CAL or OLPC programs. Our study suggests that among disadvantaged students in China's rural areas and migrant communities, there is reason to believe that computer based learning can benefit both girls and boys equally. This finding has possible implications for China's ongoing efforts to integrate computers and computing technologies into the nation's underserved schools. (C) 2012 Published by Elsevier Ltd

A double‐mode planar argon plume produced by varying the distance from an atmospheric pressure plasma jet

Abstract Atmospheric pressure planar plumes are desirable for the applications of low temperature plasmas, such as rapid modification of large‐scale surfaces. Up to now, only single‐mode planar plumes with either a streamer mode or a filamentary mode have been reported in the literature. Distinctive from the single‐mode planar plumes, a double‐mode argon planar plume has been generated in this article, which operates in the streamer mode with a larger distance away from a plasma jet and transits to the filamentary mode with decreasing the distance. Discharge characteristics and plasma parameters are compared for the two modes. Results indicate that the streamer mode and the filamentary mode correspond to pulsed and humped discharges respectively. Fast photography reveals that the streamer‐mode plume is composed of stochastically branching streamers, while the filamentary‐mode plume results from a series of moving filaments similar to those in barrier discharge. In contrast to the streamer mode, the filamentary mode has lower excited electron temperature and vibrational temperature, whereas higher electron density and gas temperature. In addition, better hydrophilicity of polyethylene terephthalate surface is achieved in the filamentary mode

Effective Virtual Screening Strategy toward Covalent Ligands: Identification of Novel NEDD8-Activating Enzyme Inhibitors

The NEDD8-activating enzyme (NAE) is an emerging target for cancer therapy, which regulates the degradation and turnover of a variety of cancer-related proteins by activating the cullin-RING E3 ubiquitin ligases. Among a limited number of known NAE inhibitors, the covalent inhibitors have demonstrated the most potent efficacy through their covalently linked adducts with NEDD8. Inspired by this unique mechanism, in this study, a novel combined strategy of virtual screening (VS) was adopted with the aim to identify diverse covalent inhibitors of NAE. To be specific, a docking-enabled pharmacophore model was first built from the possible active conformations of chosen covalent inhibitors. Meanwhile, a dynamic structure-based phamacophore was also established based on the snapshots derived from molecular dynamic simulation. Subsequent screening of a focused ZINC database using these pharmacophore models combined with covalent docking discovered three novel active compounds. Among them, compound <b>LZ3</b> exhibited the most potent NAE inhibitory activity with an IC₅₀ value of 1.06 ± 0.18 μM. Furthermore, a cell-based washout experiment proved the proposed covalent binding mechanism for compound <b>LZ3</b>, which confirmed the successful application of our combined VS strategy, indicating it may provide a viable solution to systematically discover novel covalent ligands