oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 90 )

2018 ( 2113 )

2017 ( 2104 )

2016 ( 2241 )

Custom range...

Search Results: 1 - 10 of 92279 matches for " 黄诗浩 "
All listed articles are free for downloading (OA Articles)
Page 1 /92279
Display every page Item
TDD-LTE 系统中对抗整数倍频偏的小区初始搜索算法
The Anti-Integer-Frequency-Offset Initial Cell Search Algorithm in TDD-LTE Systems
 [PDF]


Hans Journal of Wireless Communications (HJWC) , 2011, DOI: 10.12677/hjwc.2011.11001
Abstract: :LTE(Long Term Evolution,长期演进)系统中的小区初始搜索过程通过分别检测主同步信号 (Primary Synchronization Signal,PSS)和辅同步信号(Secondary Synchronization Signal,SSS)来完成,搜索结果包括小区组ID ?1?ID N 、符号定时、频偏估计、组内小区ID ?2?ID N 以及帧定时[1]。然而,若接收信号中存在整数倍频偏,则由于时域的相位旋转,主同步信号将很难用传统的相关算法检测到。提出一种主同步信号与整数倍频偏联合检测的方法,即使存在整数倍频偏,也能得到正确的符号定时。辅同步信号采用的是非相干的差分相关检测[2],仿真表明,与传统的匹配滤波算法相比,可以有效的对抗信道时延扩展和载波频偏,适用于高速场景下时分双工(Time Division Duplex,TDD)LTE 系统的同步。
In LTE systems, the initial cell search process is completed by detecting the primary synchronization signal and the secondary synchronization signal. The searching results include cell ID group, symbol timing, frequency offset estimation, intra group cell ID and frame timing[1]. However, if integer frequency offset presents in the received signal, due to time-domain phase rotation, the primary synchronization signal will be difficult to detected using the conventional correlation algorithm. A new joint detection method for integer frequency offset and primary synchronization signal is proposed, which can get the correct symbol timing even if the presence of integer frequency offset. Secondary synchronization signal is processed using the differential non-coherent correlation detection method[2]. Simulations show that compared with the traditional matched filtering algorithms, it can effectively combat the channel delay spread and carrier frequency offset and especially suitable for the high-speed scenarios in synchronization of time division duplex LTE systems.
大孔吸附树脂法富集白薇中总皂苷的工艺研究
吕永海,杨赟,,梁明金,,张卫东
中国中药杂志 , 2008,
Abstract: 目的:建立白薇总皂苷的测定方法,研究利用大孔树脂富集、纯化白薇总皂苷的工艺条件及参数。方法:选择蔓生白薇苷A为对照品建立白薇总皂苷的测定方法;以白薇总皂苷的洗脱率和精制度为指标,研究大孔吸附树脂富集、纯化白薇总皂苷的吸附性能,优化洗脱参数。结果:采用香草醛-高氯酸体系显色后测定白薇总皂苷,检测波长为518nm;大孔吸附树脂HP-20的静态吸附容量为59.3mg·g-1;白薇70%乙醇提取物以水和30%乙醇洗脱,用90%乙醇富集,所得白薇总皂苷含量达77.62%。结论:本方法可方便有效地纯化富集白薇中皂苷类化合物。
一株地衣芽胞杆菌sl-1对赭曲霉毒素a的吸附和降解研究
师磊,梁志宏,,,昆仑
农业生物技术学报 , 2013,
Abstract: ?赭曲霉毒素a(ochratoxina,ota)是一种由曲霉(aspergillusspp.)和青霉(penicilliumspp.)等丝状真菌产生的次级代谢产物,主要污染谷物、葡萄(vitisvinifera)、大豆(glycinemax)、咖啡(coffeaarabica)及其相关产品。动物实验表明,ota具有肾毒性、肝毒性,致癌、致畸和致突变性,减少或消除食品及其原料中的ota对国民食品安全至关重要。本研究以从动物粪便分离的芽胞杆菌(bacillusspp.)为材料研究ota的生物脱毒。结果显示,1株bacillusspp.sl-1既能吸附又能降解ota:活菌和高温灭活菌(121℃,20min)均能吸附ota,ota浓度为6μg/ml时,薄层层析(thinlayerchromatography,tlc)测定24h后高温灭活菌(121℃,20min)的吸附量(80%)高于活菌(60%);菌液上清能降解ota,ota浓度为6.2μg/ml时,高效液相色谱(high-performanceliquidchromatograpy,hplc)测定24h降解率为98%,没有降解产物产生。sl-1在发霉玉米中ota的降解率为35.0%。16srrna序列比对初步确定sl-1为地衣芽胞杆菌(b.licheniforms)。本研究首次获得了1株既能吸附又能降解ota的b.licheniforms,为ota的生物脱毒提供了新材料。
铝合金叠层板钻削层间毛刺高度预测模型
Predictive model for the interlayer burr height during drilling of stacked aluminum plates

吴丹,,高雨,董云飞,马信国
- , 2017, DOI: 10.16511/j.cnki.qhdxxb.2017.26.024
Abstract: 叠层构件制孔容易生成层间毛刺,严重影响加工质量和效率。为了探究层间毛刺生成过程,预测毛刺高度,提出有效控制层间毛刺的工艺方法,该文首先通过实验建立钻削轴向力经验公式,然后采用有限元方法计算单层板在理论钻削力下的变形量,进而预测层间毛刺生成初始位置,最后运用能量法建立叠层钻削层间毛刺高度理论模型。应用硬质合金麻花钻在铝合金叠层试件上开展钻削实验,结果表明:理论模型能够有效地预测层间毛刺高度,揭示进给量和层间间隙对层间毛刺的影响规律,有助于优化叠层钻削工艺参数。
Abstract:The drilling of stacked components tends to form interlayer burrs, which reduce machining quality and the production efficiency. This study analyzes the formation and height of interlayer burrs and presents an effective processing method to control interlayer burrs. An empirical formula was developed for the thrust force during drilling for an finite element analysis (FEA) model of the drilling process to product the single plate deformations and to find the initial burr formation position. Then, the energy method is used in a mechanical model to product the interlayer burr height. The predictions agree well with drilling experiments with stacked aluminum plates and a carbide drill. The results show the effects of the feed rate and the interlayer gap on the interlayer burr formation to optimize the processing parameters of stacked components.
锌粉催化合成含硅芳炔树脂
,蒋孝杰,周燕,,杜磊,夏红娟,发荣
过程工程学报 , 2014,
Abstract: 以二乙炔基苯和二甲基二氯硅烷为原料,通过锌粉催化合成含硅芳炔树脂,确定了合成产物的结构.结果表明,以乙腈为溶剂、锌粉过量200%、温度80℃、反应时间10h为最佳反应条件,反应收率达82%以上;所制含硅芳炔树脂有良好的加工性能,在约170℃可发生交联固化反应;树脂的热稳定性良好,在N2气氛下失重5%时的温度为529℃,800℃时树脂残留率约为85%.
温拌沥青混合料设计方法与路用性能研究
Research on the Performance and Design Method of Warm Asphalt Mixture
 [PDF]

,
Hans Journal of Civil Engineering (HJCE) , 2013, DOI: 10.12677/HJCE.2013.21001
Abstract:
针对表面活性类温拌技术的压实特性、设计方法以及性能开展了研究,重点确定了温拌沥青混合料的成型方法和性能评价等方面内容。选择ACSMAUTASUP四类级配和普通沥青、改性沥青两种胶结料进行温拌沥青混合料性能对比分析。
In this paper, research is carried out on the compaction characteristics, design methods and performance of the surfactant class warm mix technology. Warm mix asphalt molding methods and performance evaluation are focused. AC, SMA, UTA and SUP are chosen with ordinary asphalt and modified asphalt to evaluate performance of warm mixture respectively.
从麦棉单产比看黄淮海平原棉花布局的调整
铿?
中国农业资源与区划 , 1986, DOI: 10.7621/cjarrp.1005-9121.19860517
Abstract: 近年由于棉花生产效益高,棉花得到突飞猛进地发展。黄淮海平原1980年棉田面积2567万亩,产皮棉2072万担,到1983年棉田面积增加到4346万亩,皮棉5109万担,分别增加了69%和142%。黄淮海平原1983年的棉田面积约占全国总数的一半,皮棉产量则占全国一半以上。由于棉田大量增加,致使棉花供过于求,现大量积压。
整体式热流道热嘴易断裂问题探讨
Discussion on the Problem of Breakable Nozzle of Integral Hot Runner
 [PDF]

王焕, 张茜, 钟少基,
Mechanical Engineering and Technology (MET) , 2015, DOI: 10.12677/MET.2015.44030
Abstract:
热流道中热嘴断裂严重影响了整体式热流道的使用寿命,制约了热流道技术在模具中的推广和应用,为了解决断裂问题,本文就此展开讨论。结合热嘴自身结构和使用环境因素综合考虑,归纳出四个主要因数:螺纹连接的缺陷、温度的影响、针阀冲击、注射压力,同时对每一种影响因数进行了详细的计算。针对断裂现象提出了三种改进方案。改进后的热流道系统断裂现象明显减少,极大地提高了系统的可靠性和使用寿命。
Nozzle fracture of hot runner severely affects the overall service life of hot runner, restricting the promotion and application of hot runner technology in the mold. In this paper, we discussed the fracture problem in order to solve it. Taking into account the structure and use environment of the nozzle, four main factors of the fracture problem were summarized: threaded connection defect, temperature effect, needle valve shock, and injection pressure. And then each impact factor was calculated in detail. Aiming at the fracture, three improvement projects were also proposed. Frac-ture had been reduced significantly in the improved hot runner system, greatly enhancing the re-liability and service life.
基于居群变异的(蜓)种鉴定——以Eopolydiexodina为例

中国科学 地球科学 中国科学 地球科学 , 2011,
Abstract: ?为使类形态种更接近客观真实的生物种,在类化石鉴定中应从居群概念出发,利用居群的形态变异特征约束传统的形态鉴定.根据滇西小新寨剖面中二叠世沙子坡组单层采集的样品,笔者度量了其中Eopolydiexodina个体的特征形态参数(初房直径、内外圈尺寸与轴率),并进一步结合形态统计学方法进行了化石居群层次的形态种鉴定.研究结果表明,该单层中Eopolydiexodina个体的特征形态参数虽表现出较大范围的变异,但形态变异基本连续且满足正态分布.因此,所研究个体的形态变异符合单个居群的形态变异特征,宜根据居群思想视作同一种.本文的研究结果支持了同层产出的同属类个体组成单个化石居群的假设.
马克思哲学终结观的内涵

安徽师范大学学报(人文社会科学版) , 2014,
Abstract: 学界对于马克思是否哲学终结论者这一问题,已形成了一场争论,其症结在于没有对“哲学终结”中的“哲学”进行具体的界定。从作为哲学形态的哲学、作为意识形态的哲学、作为文化形态的哲学三个层面对马克思的哲学终结思想的内涵进行了澄清。
Page 1 /92279
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.