oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Hard X-ray photoelectron spectroscopy on buried, off-stoichiometric CoxMnyGez (x : z = 2 : 0.38) Heusler thin films  [PDF]
Siham Ouardi,Gerhard H. Fecher,Stanislav Chadov,Claudia Felser,Benjamin Balke,Xenia Kozina,Tomoyuki Taira,Masafumi Yamamoto
Physics , 2012, DOI: 10.1007/s00339-013-7565-y
Abstract: Fully epitaxial magnetic tunnel junctions (MTJs) with off-stoichiometric Co2-based Heusler alloy shows a intense dependency of the tunnel magnetoresistance (TMR) on the Mn composition, demonstrating giant TMR ratios of up to 1995% at 4.2 K for 1. This work reports on the electronic structure of non-stoichiometric CoxMnyGez thin films with a fixed Co/Ge ratio of x : z = 2 : 0.38. The electronic structure was investigated by high energy, hard X-ray photoelectron spectroscopy combined with first-principles calculations. The high-resolution measurements of the valence band of the non-stoichiometric CoxMnyGez films close to the Fermi energy indicate a shift of the spectral weight compared to bulk Co2MnGe. This is in agreement with the changes in the density of states predicted by the calculations. Furthermore it is shown that the co-sputtering of Co2MnGe together with additional Mn is an appropriate technique to adjust the stoichiometry of the CoxMnyGez film composition. The resulting changes of the electronic structure within the valence band will allow to tune the magnetoresistive characteristics of CoxMnyGez based tunnel junctions as verified by the calculations and photoemission experiments.
状态方程与量测方程均含有参向量的递推滤波  [PDF]
汪咬元
科学通报 , 1985,
Abstract: 状态方程为量测方程为X_k——状态向量,Z_k——量测向量,θ~((1)),θ~((2))未知参向量,Φ_(k,k-1)(满秩),A_k,B_k,Γ_k,H_k是有适当维数的已知常矩阵,W_k,V_k是互不相关的白噪声序
基于arnoldcat变换的图像位置均匀置乱算法  [PDF]
张健,于晓洋,任洪娥
计算机应用 , 2009,
Abstract: ?图像置乱算法arnoldcat变换存在密钥量小和通用性差的缺点,为此,从图像置乱的实质出发,提出均匀置乱的概念,并对arnoldcat变换进行了改进,提出图像位置均匀置乱算法。实验结果表明,新算法密钥量显著提高,置乱效果理想,同时可以抵抗剪切攻击。
Intrinsic Properties of Stoichiometric LaOFeP  [PDF]
T. M. McQueen,M. Regulacio,A. J. Williams,Q. Huang,J. W. Lynn,Y. S. Hor,D. V. West,M. A. Green,R. J. Cava
Physics , 2008, DOI: 10.1103/PhysRevB.78.024521
Abstract: DC and ac magnetization, resistivity, specific heat, and neutron diffraction data reveal that stoichiometric LaOFeP is metallic and non-superconducting above T = 0.35 K, with gamma = 12.5 mJ/mol*K. Neutron diffraction data at room temperature and T = 10 K are well described by the stoichiometric, tetragonal ZrCuSiAs structure and show no signs of structural distortions or long range magnetic ordering, to an estimated detectability limit of 0.07 uB/Fe. We propose a model, based on the shape of the iron-pnictide tetrahedron, that explains the differences between LaOFeP and LaOFeAs, the parent compound of the recently discovered high-Tc oxyarsenides, which, in contrast, shows both structural and spin density wave (SDW) transitions.
中国白蜡虫Z(Ericeruspelachavannes)泌蜡量研究  [PDF]
动物学研究 , 1988,
Abstract: 通过对我国不同地区繁育的白蜡虫泌蜡实验,表明云南,四川,贵州三省白蜡虫泌蜡量多,其它省区的白蜡虫泌蜡量少.据此建议生产部门在以上三省大力提倡发展白蜡虫生产.
Stoichiometric and Catalytic Synthesis of Alkynylphosphines  [PDF]
Elise Bernoud,Romain Veillard,Carole Alayrac,Annie-Claude Gaumont
Molecules , 2012, DOI: 10.3390/molecules171214573
Abstract: Alkynylphosphines or their borane complexes are available either through C–P bond forming reactions or through modification of the phosphorus or the alkynyl function of various alkynyl phosphorus derivatives. The latter strategy, and in particular the one involving phosphoryl reduction by alanes or silanes, is the method of choice for preparing primary and secondary alkynylphosphines, while the former strategy is usually employed for the synthesis of tertiary alkynylphosphines or their borane complexes. The classical C–P bond forming methods rely on the reaction between halophosphines or their borane complexes with terminal acetylenes in the presence of a stoichiometric amount of organometallic bases, which precludes the access to alkynylphosphines bearing sensitive functional groups. In less than a decade, efficient catalytic procedures, mostly involving copper complexes and either an electrophilic or a nucleophilic phosphorus reagent, have emerged. By proceeding under mild conditions, these new methods have allowed a significant broadening of the substituent scope and structure complexity.
z箍缩软x射线辐射能量薄膜量热计改进技术  [PDF]
李沫,王亮平
强激光与粒子束 , 2013,
Abstract: ?薄膜量热计是进行z箍缩辐射总能量测量的主要手段之一,准确可信的总能量参数对z箍缩研究具有重要意义。对薄膜量热计装置进行技术改进,采用脉冲恒流源代替脉冲恒压源驱动镍薄膜量热计,撤除了回路中的串接电阻,可直接测量薄膜探测器的电阻变化,从而有效提高了辐射总能量测量的精度,拓宽了该设备的适用范围,使其可对目前“强光一号”加速器z箍缩实验中所有典型负载进行测量。改进后平面型铝丝阵负载实验中总能量测量的相对不确定度由49.0%降低为19.6%。与闪烁探测系统功率测量结果积分值进行了对比,二者比值在0.87~1.04之间。
Z轴离焦量对激光熔覆成形的影响  [PDF]
练国富,杨谡,黄旭,江吉彬
- , 2018, DOI: 10.3969/j.issn.0253-2778.2018.03.007
Abstract: 为了深入探究Z轴离焦量对激光熔覆成形的影响,综合考虑Z轴离焦量导致的熔池粉末利用率、激光能量密度等因素对熔覆成形的影响,通过改变激光功率、扫描速度、气流量、离焦量4个因素进行L16(44)正交试验,以及Z轴离焦量变化的单因素试验,揭示激光功率、扫描速度、气流量、离焦量4个因素对熔覆成形的耦合作用规律.正交试验结果表明,离焦量、激光功率、扫描速度、气流量在激光熔覆成形中都扮演着重要角色,对熔覆效率的因素影响主次为:激光功率>气流量>离焦量>扫描速度.Z轴离焦量单因素试验结果表明:激光熔覆过程需要一定的离焦量才能获得最佳熔覆质量;当离焦量为5mm时,熔覆层的高度最高;当离焦量小于或大于5mm时,熔覆层高度降低;当Z轴离焦量逐渐增加时,粉末利用率先逐渐增加再逐渐减少.
Abstract:The variation of distance between laser head and substrate (named defocus distance) has a considerable effect on powder utilization efficiency and energy density, therefore affecting the laser cladding forming (LCF) process. Orthogonal experiments L16 (44) of the four parameters: laser power, scanning speed, gas flow rate and defocusing distance and single factor experiment of the defocusing distance along Z axis were conducted to investigate the coupling effects of these parameters on LCF process. The result of orthogonal experiment suggests that all four parameters play important roles in LCF, and the order of factors which affect the cladding efficiency is: laser power>gas flow rate>defocusing distance>scanning speed. The result of the single factor experiment indicates that the optimal cladding quality occurs when the defocusing distance reaches a certain level. The maximum cladding layer height can be achieved when the defocusing distance is 5mm. The cladding layer height is reduced when the defocusing distance is less or larger than 5mm. It is proved that the powder utilization efficiency gradually increases and then decreases when the defocusing distance keeps increasing.
利用薄膜量热计测量高功率z箍缩软x射线总能量  [PDF]
王文生,何多慧,邱爱慈,蒯斌,罗建辉
强激光与粒子束 , 2003,
Abstract: ?介绍一种采用脉冲恒压电源驱动的镍薄膜量热计,研制了测量系统和镍薄膜探测器,对探测器的电阻温度特性进行了实验标定,该量热计已成功应用于测量“强光一号”加速器高功率z箍缩等离子体软x射线总能量,分析了测量不确定度。
Determination of stoichiometric coefficients by the matrix method
Tadi? Goran S.,Pejovi? Branko В.,Gligori? Miladin J.,Mi?i? Vladan M.
Hemijska Industrija , 2007, DOI: 10.2298/hemind0701018t
Abstract: The problem of calculating stoichiometric coefficients in a chemical equation can be solved by standard methods and the method of multidimensional vector space, but good knowledge of vector algebra is required. In this paper, the authors proposed a matrix method and other treatment of the problem was given as the authors' own interpretation. A matrix was formed in the form of base using all the elements which take place in a chemical reaction, after which the matrixes of all the chemical compounds were determined based on numerical indexes and element symbols. This approach enables the setting of a principal matrix equation based on a mathematical approach. The solutions of this matrix equation are the desired stoichiometric coefficients that form a balanced equation. A new approach to tabular solving is presented. This method, compared to existing standard methods, is faster, simpler, and more effective, especially for complex chemical equations. The method was tasted on examples from inorganic chemistry and metallurgy.
Page 1 /100
Display every page Item


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