TiO_2和UV531对PAN防紫外线纳米纤维的影响分析

为了研究不同防紫外线添加剂对PAN纳米纤维的影响,在聚合物PAN溶液中分别加入了TiO_2与UV531,利用静电纺丝技术制备了PAN仪等仪器对比分析了纯PAN、PAN/UV531、PAN严重,表面会有TiO_2颗粒聚集;红外光谱图显示PAN说明TiO_2与UV531的加入并未改变聚合物PAN的分子基团结构;添加防紫外线的TiO_2与UV531后,PAN纳米纤维膜的防紫外线性能有了卓越的提升,添加剂的含量越高,紫外线防护性能越好,对UVA和UVB的透射率越小。     

脱胶方法对普洱茶籽油中金属含量的影响

普洱茶籽油中所含的金属是引起普洱茶籽油酸败、高温褐变的主要原因.为了有效降低普洱茶籽油中的金属含量,采用火焰原子吸收光谱法,比较了水化脱胶、磷酸脱胶、柠檬酸脱胶法获得的脱胶普洱茶籽油中的Fe、Cu、Mn、Mg等金属的含量.结果表明,磷酸脱胶对油中金属的去除效果最好.     

跨国公司对发展中国家经济的双重影响

跨国公司是国际直接投资的主体。跨国公司投资对发展中国家经济有积极影响,也有消极影响。权衡之下,利大于弊,我们应该更多、更好地利用跨国公司投资,促进经济更快地发展与增长。同时,对于跨国公司带来的负面影响,必须高度重视和警觉。发展中国家要制定得力的对策,加强对跨国公司投资的引导、管理和监督,趋其利,避其害。     

Performance analysis of UWB a impulsive noise radio systems under cass environment

The performance of UWB （Ultrawide Bandwidth） radio Systems Under class A impulsive noise environment is studied in this paper. First, while employing the Middleton＇ s class A model as a model of impulsive noise, the statistical characteristics of in-phase and quadrature components of impulsive noise is investigated. It is proven that, unlike Gaussian noise, they are dependent especially due to the fact that impulsive indices are small. Next, using this above dependence, a novel UWB radio receiver designed for impulsive noise is proposed and the exact expression for the average BER （ Bit Error Rate） of this receiver as a function of SNR （ Signal to Noise Power Ratio） and threshold value is derived. Then, the optimum threshold value is discussed and the performance of UWB radio systems with the proposed receiver designed for impulsive noise and with the conventional receiver designed for Gaussian noise under impulsive noise environment is estimated, Numerical results are compared and show that the influence of impulsiveness index and threshold value on the performance of UWB radio systems is quite large and that the performance achieved by the proposed UWB radio receiver is much superior to that of the conventional UWB radio receiver under class A impulsive noise environment.     

创新曲线上的灵魂舞者——三星笔记本的创新文化

善于发现机会和把握机会的人,能在平常处发掘别样风景,在同业中脱颖而出、鹤立鸡群。而在三星看来,这些还远远不够。真正的智者,是在机会之上赋予事物更多创意,使其具有更强大的新鲜生命活力和竞争力,超越机会本身的意义,创造新生。     

500kV御道口输变电工程过电压研究

针对京津唐电网第一个500 k V超高压、长距离、大容量的风电汇集送出输变电工程-御道口输变电工程的工频过电压、操作过电压、直流偏置及铁磁谐振等问题进行了研究。针对工程单线带单站单变的特点,给出了启动调试及系统正常运行期间相关运行方式的推荐意见,以期为同类工程提供建设、启动调试及运行的参考意见。     

PVDF/BaTiO3复合纳米纤维滤膜的制备及性能

为了制备高效低阻的纳米纤维空气过滤膜,采用静电纺丝技术,以钛酸钡(BaTiO_3)作为驻极体,制备了不同质量分数、不同纺丝时间的PVDF/BaTiO_3复合驻极纳米纤维膜,并对其微观结构、表面化学结构、透气性能、透湿性能、过滤性能进行了研究分析。结果发现:当BaTiO_3的质量分数为0.8%、纺丝时间为40 min时,制备的PVDF/BaTiO_3复合纳米纤维滤膜性能达到最优,此时纳米纤维滤膜的透气率最大达369 mm/s,透湿量最大达4 672.79 g/(m~2·d),过滤效率为76.8%,阻力压降为11.76 Pa,品质因子最大值达0.124 2。     

化工园区基础设施低碳发展路径研究

结合“双碳”目标战略,分析研究了现阶段我国化工园区基础设施碳排放特点;提出了包括化工园区供热系统、给排水系统、物流交通系统、废物治理系统等基础设施实施低碳发展路径的建议;指出化工园区基础设施的低碳发展将助力和推动我国化工园区绿色低碳发展目标的实现。     

Performance analysis of UWB radio systems under cass a impulsive noise environment

Much attention has been paid to a new form ofspread spectrum technique called the UWB-IR(Ultraw-ide Bandwidth-Impulse Radio)system for future highspeed wireless communication services[1,2].For lowcomplexity implementation,UWB systems usually usetime hopping spread-spectrum(THSS)impulse trainwith pulse position modulation(PPM)to carry data in-formation[3].That is why they are sometimes called IR.UWB radio systems,as one of the promising solutionsfor short range wireless communications[…     

国土空间规划体系下化工园区控制性详细规划编制思考与建议

介绍了我国国土空间规划体系建设全面启动的背景、定位、框架与编制要求,并通过解析国土空间规划体系对控制性详细规划的要求,深入分析了目前化工园区控制性详细规划编制存在的问题和面临的挑战.在此基础上,对化工园区控制性详细规划编制提出了一些新的思考和建议.