Temporal scale effect of loading data on instream nitrate-nitrogen load computation

The temporal scale effect of loading data on nitrate-nitrogen load computation was examined using outputs of watershed modeling tool Hydrologic Simulation Program-FORTRAN (HSPF) for the Amite River in Louisiana, USA. The daily nitrate-nitrogen concentrations simulated using the HSPF were employed first to obtain daily, weekly, bi-weekly, and monthly average data and then to develop load duration curves for the data with four different temporal scales. The duration curves exhibited high variability in the load estimated using daily data as compared with those based on bi-weekly and monthly data. According to daily data, the nitrate-nitrogen load in the winter was found to be 2,780 kg. The nitrate-nitrogen load decreased with increasing temporal (daily, weekly, bi-weekly, and monthly) scale (commonly used in water quality monitoring) of the data. The coefficient of variation, used to quantify the effect of temporal scale on the load, was found to be linearly and inversely correlated with the logarithm of the time scale. Based on the finding, empirical equations were proposed to extrapolate near real-time data for flow and nitrate-nitrogen, greatly simplifying nutrient monitoring and reducing the cost involved in water quality monitoring.     

Least squares recursive projection twin support vector machine for classification

In this paper we formulate a least squares version of the recently proposed projection twin support vector machine (PTSVM) for binary classification. This formulation leads to extremely simple and fast algorithm, called least squares projection twin support vector machine (LSPTSVM) for generating binary classifiers. Different from PTSVM, we add a regularization term, ensuring the optimization problems in our LSPTSVM are positive definite and resulting better generalization ability. Instead of usually solving two dual problems, we solve two modified primal problems by solving two systems of linear equations whereas PTSVM need to solve two quadratic programming problems along with two systems of linear equations. Our experiments on publicly available datasets indicate that our LSPTSVM has comparable classification accuracy to that of PTSVM but with remarkably less computational time.     

Microwave permeability of single cobalt nanotube studied by micromagnetics simulations and generalized Snoek’s law

Microwave permeability spectra of single Co nanotube under equilibrium state have been studied by micromagnetics simulation.More than four obvious resonance peaks have been found(11.72,24.20,33.18 and 39.55 GHz).Such large resonance frequency cannot be found in other traditional magnetic materials.The configurations of magnetic moments along the nanotube have been simulated.The results show that the top end of nanotube has a"flow-out"pattern of magnetic moments configuration.The bottom end has a"flow-in"pattern of magnetic moments configuration.The magnetic moments within the main body of nanotube are aligned perfectly along the length of nanotube.The magnitude of natural resonance peak is strongly related to the volume fraction of a zone,which has the same orientation of magnetic moments.Large microwave permeability values have been found for single nanotube.The generalized Snoek’s law has been used to validate the micromagnetics simulations in this paper.     

以太网供电技术及受电端电路设计

为解决具有以太网接口的小型功率设备供电不便的问题,在分别分析IEEE 802.3af标准中的以太网供电系统构成、以太网供电传输方式、以太网供电过程及其他电气特性的基础上,提出了一种通过以太网获取电源的解决方案,并给出了详细的电路设计原理图。该方案可同时支持以太网供电输入和其他辅助电源输入,并可以同时输出3.3 V和5 V这2种电压供系统使用。测试结果表明,该设计方案具有较低的成本和较高的效率,能够很好地解决小型功率设备供电不便的问题。     

内燃式热风炉改造气烧石灰窑实践

介绍了将已停用但仍完好的内燃式热风炉炉体经过改造，增加上料、出料及必要的烧制设备等，利用高炉富余的煤气，改造成煤气烧。实践证明，改造后的石灰窑经济效益显著。     

张家口电厂锅炉"四管"爆漏情况回顾、分析与反措

通过总结张家口发电厂第一台机组投产以来锅炉“四管”爆漏发生的次数、原因，分析了在防止锅炉爆管方面采取的措施，肯定了目前取得的成绩，以供借鉴。     

微振动对空间实验室微重力环境的影响研究

针对大型刚柔组合体空间结构(空间实验室)的特点,建立系统的动力学方程,并对机柜内设备、太阳阵的转动、宇航员活动产生的激扰力进行了简化。利用计算机建立组合体的简化模型,对空间组合体在各种微振动激扰下的加速度响应进行了仿真研究,并将这些仿真结果用于空间实验室微重力环境的预测。     

室温固相反应法制备纳米氧化锆及表征

以ZrOCl2.8H2O和NH4HCO3为原料,在适量表面活性剂(PEG-400)存在下,先在室温下充分混合研磨进行固相反应,得到的反应混合物再用水洗去其中的可溶性无机盐并烘干,即得氧化锆前驱体。前驱体经530℃下热解3h即得氧化锆产品,采用TG/DTA,XRD和TEM对前驱体及产品进行了表征。结果表明,所得产品氧化锆为结晶良好、以四方相为主的混合晶相,其平均粒径约为25nm。