oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 124 )

2018 ( 2935 )

2017 ( 3005 )

2016 ( 3150 )

Custom range...

Search Results: 1 - 10 of 130359 matches for " 丁泽文 "
All listed articles are free for downloading (OA Articles)
Page 1 /130359
Display every page Item
离心铸造过共晶Al-Si合金自生表面复合材料
王渠东,,金俊
复合材料学报 , 1998,
Abstract: 采用热模金属型工艺,离心铸造过共晶Al-Si合金,获得了外层或外层和内层富集初晶Si,其余部分为共晶组织构成的自生表面复合材料。分析了复合材料的形成过程,考察了复合材料的组织、硬度和耐磨性。
基于星历数据的SAR多普勒参数计算
,曾涛,
北京理工大学学报 , 2010,
Abstract: 改进了基于星历数据的星载合成孔径雷达多普勒计算方法.改进的方法有效地将J2摄动(地球扁率摄动)对近地点幅角和升交点赤经的影响引入到多普勒参数的计算中,得到了更准确的多普勒参数,对改进方法与传统方法的差别进行了分析.计算机仿真结果验证了改进方法的正确性.
高分辨率的凝胶色谱担体─—聚烯丙基右旋糖酐凝胶Acryldex
郭洪,,李荣朝,杨萍,,沈恩鲁
色谱 , 1995,
Abstract: 介绍了国内首次研制成功的凝胶色谱介质─—交联聚烯丙基右旋糖酐凝胶Acryldex。它在色谱性能,理化性能方面,如:色泽、化学稳定性(耐酸、耐碱、热压)、工作压力、洗脱流速、分辨率以及对蛋白质的吸附性等均已达到同类世界名优产品SphacrylS-200及S-300的水平,完全可替代进口,为我国生物技术的发展提供有效的分离纯化工具。
基于修正斜距模型的GEO SAR远地点的CS成像算法
,刘大成,王冠宇,,胡程
北京理工大学学报 , 2014,
Abstract: 针对地球同步轨道SAR(GEOSAR)卫星的轨道曲率大,若使用传统直线斜距模型,将不能正确地描述卫星处于远地点时场景目标的“近远近”斜距历程,建立了一种曲率为负的修正斜距模型.该模型能够准确地描述远地点目标的斜距历程;基于该修正的斜距模型精确地推导了GEOSAR远地点回波信号的二维频谱表达式,并给出了一种适用于GEOSAR远地点成像的修正CS成像算法;在方位向成像处理时补偿随距离线性变化速度引起的空变相位,实现GEOSAR较宽的成像幅宽的聚焦处理.并通过场景尺寸为100km×100km点阵的GEOSAR成像处理,验证了该基于修正斜距模型的CS成像算法的有效性.
新型力反馈双向伺服系统干扰观测器PID控制算法的研究
广,章甫,,姚必强,张敬东,
重庆邮电大学学报(自然科学版) , 2006,
Abstract: 针对目前力反馈双向伺服遥操作工程机器人控制系统所存在的反馈力冲击过大及主从位移控制的随动性较差等问题,提出了在新型力反馈伺服系统中加入干扰观测器来改善从动机构的动态特性差异,从而提高从动机构的鲁棒稳定性和抗干扰能力。仿真结果表明提出的方法是有效的。
硅微机械悬浮结构电感的设计与制作工艺研究
,,刘理天,李志坚
电子学报 , 2002,
Abstract: 本文系统分析了影响平面螺旋电感Q值的主要因素,并制作出一种应用于射频通信的硅微机械悬浮结构电感.在考虑趋肤效应、涡流损耗等高频电磁场效应对电感Q值的影响后,获得了微机械电感的简化电学模型,得到了具有较高Q值电感的优化结构.在制作硅微机械电感的工艺过程中,采用多孔硅作为牺牲层材料,将螺旋结构铝线圈制作在二氧化硅薄膜上,在使用添加了硅粉和过硫酸铵的TMAH溶液释放牺牲层之后,得到设计值为4nH的悬浮结构微机械平面螺旋电感.实验结果证明,整个工艺流程可靠,并与CMOS工艺兼容.
花生内生抗虫工程菌的应用研究
立孝,倪新江,王东昌,宋子红,
吉林农业大学学报 , 2001,
Abstract: ?研究了带有bt基因的花生内生菌对花生生物学特性、酶活性及抗虫性的影响。结果表明:3种不同处理方法(浸种、喷施、浸种+喷施)均能增加花生体内的超氧化物歧化酶(sod)和过氧化物酶(pod)的活性,提高花生的株高、分枝数、主根长和地上部、地下部鲜重等生物学指标,并对棉铃虫表现出了一定抗性。在3种处理方法中均以浸种+喷施效果最佳,而浸种或喷施2种处理方法其效果因品种不同而异。
Nrf2调控SIRT6表达的初步研究
,,刘新华,刘海霞,,温传俊
南京师范大学学报(自然科学版) , 2015,
Abstract: 衰老是一个普遍的、动态的,并持续发展的复杂过程.对其机制的研究中,比较公认的是氧化应激损伤理论,其中核转录因子Nrf2发挥重要的作用,这一理论主要强调在寿命调节中Nrf2的抗氧化作用.而本实验结合生物信息学、生物化学、细胞生物学等方法证明去乙酰化酶蛋白家族成员SIRT6的表达受Nrf2的调控,即提示Nrf2的抗衰老作用可能是通过SIRT6发挥作用.
Agingisanuniversal,dynamic,complexprocess.Theoxidativestresstheoryisagenerallyrecognizedexplanationofamolecularmechanismunderlyingtheagingprocess.ThenucleartranscriptionfactorNrf2playsanimportantroleinthisprocess.AseriesofexperimentsweredonetoverifythatSIRT6wasapossibletargetgeneofNrf2anditmayactinconjunctionwithNrf2
氧化石墨烯增强环氧树脂复合材料的制备及其力学性能研究
胡涛,赵东林,程兴旺,孟朔,,吴路路
- , 2018, DOI: 10.13543/j.bhxbzr.2018.06.005
Abstract: 以天然石墨为原料,利用改进的Hummers法制备氧化石墨烯,并对其进行X-射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)表征。之后利用一种新型的有机溶剂三缩水甘油基对氨基苯酚(TGPAP)作为相转移剂和表面活性剂,将氧化石墨烯(GO)从水溶液转移到环氧树脂基体中,去除水分,加入固化剂进而得到混合液,最后利用浇铸法得到复合材料。通过万能测试拉力机对复合材料的拉伸性能和弯曲性能进行测试,结果表明氧化石墨烯的加入能够有效增强复合材料的力学性能:在添加0.1%(质量分数)的氧化石墨烯时,复合材料拉伸强度达到最大值77.29 MPa,与不添加氧化石墨烯相比提高了26.60%;在添加1.0%的氧化石墨烯时,拉伸模量达到最大值2 451.99 MPa,与纯环氧树脂相比提高了21.69%。
Abstract:Graphene oxide has been prepared from natural graphite by the well-known Hummers' method with some modifications and the GO was characterized by XRD and FT-IR. Triglycidyl para-aminophenol (TGPAP) was used to facilitate direct and rapid transfer of the GO dispersion from water to an epoxy resin. The TGPAP acted not only as a phase transfer agent but also as an efficient surface modifier. Removal of the water from the epoxy resin and additon of hardener to the mixture afforded composite materials by a casting method. The tensile and flexural properties of the composites were measured with a universal tensile testing machine. The result showed that the mechanical properties were enhanced after the addition of graphene oxide. When the concentration of GO in the epoxy matrix was 0.1 wt.%, the tensile strength reached its maximum value of 77.29 MPa, which is 26.60% higher than that without GO, and the tensile modulus reached a maximum of 2 451.99 MPa at a GO concentration of 1.0wt.%, which is 21.69% higher than the corresponding value for the pure sample.
采用主成分分析与梯度金字塔的 高动态范围图像生成方法
A Generating Method of High Dynamic Range Images Using Principal Component Analysis and Gradient Pyramid

张淑芳,,,刘孟娅,郭志鹏
- , 2018, DOI: 10.7652/xjtuxb201804022
Abstract: 针对由多曝光低动态范围(LDR)图像融合生成高动态范围(HDR)图像对采集设备要求高且不适用于动态场景的问题,提出一种采用主成分分析(PCA)与梯度金字塔的HDR图像生成(HDR-PGG)方法。首先用改进的S曲线全局映射和Retinex局部色调映射对PCA变换后的亮度图像进行处理,以避免光晕和泛灰,并结合PCA逆变换获取多曝光LDR图像;其次利用多曝光LDR图像的对比度、饱和度、曝光度和亮度信息构造标量权重图,确保生成的HDR图像亮暗区域分明且细节清晰;最后,利用梯度金字塔生成HDR图像。实验结果表明,当视觉差异大于75%时,由HDR-PGG方法生成的HDR图像的平均像素分布概率比拉普拉斯金字塔和梯度金字塔算法降低了10.84%和30.75%,其平均相对熵与噪声程度比值分别提高了0.542 1和0.508 9。
A generating method (HDR??PGG) of high dynamic range (HDR) images using principal component analysis (PCA) and gradient pyramid is proposed to solve the problem that HDR image generated by the fusion of multi??exposure low dynamic range (LDR) images has high requirements for sampling equipment and is not applicable to dynamic scenarios. Firstly, the improved S??curve global mapping algorithm and the Retinex tone mapping algorithm are used to process a PCA transformed luminance image so that halo and graying are avoided, and the PCA inverse transformation is used to obtain multi??exposure LDR images. Secondly, the information of contrast, saturation, exposure and luminance of multi??exposure LDR images are used to construct scalar weight maps to ensure that the bright and dark areas of the generated HDR image are distinct, and the details in the HDR image are clear. Finally, the HDR image is fused using the gradient pyramid. Experiments are performed and the HDR images generated by HDR??PGG are compared with those by the Laplacian pyramid algorithm and the gradient pyramid algorithm. The results show that the average pixel distribution probability of HDR images generated by HDR??PGG method reduce by 10.84% and 30.75% when the visual difference is over 75%, respectively, and the average relative entropy and the noise ratio increases by 0.542 1 and 0.508 9, respectively, compared with those of the Laplacian pyramid algorithm and the gradient pyramid algorithm
Page 1 /130359
Display every page Item


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