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An improved empirical green function method to extract microseismic signals
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作者 Dayong Yu Pan Wang 《大地测量与地球动力学:英文版》 2019年第1期42-48,共7页
In mining, reservoir impoundment and hydraulic fracturing exploitation, the induced microseismic clusters may present complex waveforms at receivers since the individual events generally arrive very close. And the rou... In mining, reservoir impoundment and hydraulic fracturing exploitation, the induced microseismic clusters may present complex waveforms at receivers since the individual events generally arrive very close. And the routine methods for arrival picking are insufficiently efficient due to these strong influences. Here, we modified the empirical green function method and applied it to extract the green functions and the radiation coefficients of microseismic events with the largest energy in clusters.Multiple-channel records were used to estimate an 'average' source spectrum and then the 'average' source wavelet was removed from the records by deconvolution. We applied this method to the real data,and the result indicated clear improvement in extracting the dominant event of the clusters. 展开更多
关键词 Microseismic SIGNALS Empirical green FUNCTION SOURCE SPECTRA
Influence of annealing treatment on the luminescent properties of Ta:β-Ga2O3 single crystal
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作者 余小威 崔慧源 +2 位作者 朱茂东 夏志林 赛青林 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第7期475-478,共4页
Ta5+doped β-Ga2O3 single crystals were grown by using the optical floating zone method, and then annealed in the air and nitrogen gas at 1400℃ for 20 hours.The transmittance spectra, photoluminescence(PL), x-ray irr... Ta5+doped β-Ga2O3 single crystals were grown by using the optical floating zone method, and then annealed in the air and nitrogen gas at 1400℃ for 20 hours.The transmittance spectra, photoluminescence(PL), x-ray irradiation spectra, and PL decay profiles of the samples were measured at room temperature.The relevant results show that the optical transmittance of the samples annealed in the air or nitrogen gas was improved.By drawing the(ahv)2–hv graph,it can be seen that the band gap decreased after being annealed in the air, but increased in nitrogen gas.The PL spectra and x-ray irradiation spectra show that the luminescent intensity of the sample annealed in the air increased substantially,while decreased for the sample annealed in nitrogen.The PL decay time of the Ta:β-Ga2O3 annealed in the air increased significantly compared with that of the Ta:β-Ga2O3 sample without annealing, but the tendency after annealing in nitrogen gas was opposite. 展开更多
关键词 Ta:β-Ga2O3 FLOATING zone method TRANSMITTANCE spectra ANNEALING
Measurement of the prompt neutron spectrum from thermalneutron- induced fission in U-235 using the recoil proton meth 预览
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作者 Tie He Pu Zheng Jun Xiao 《核技术:英文版》 SCIE CAS CSCD 2019年第7期68-76,共9页
A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculatio... A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculation and validation of the response matrix, are presented. The PFNS for ^235U in the energy range 1–12 MeV, induced by thermal neutrons, was obtained. The measured spectrum in the low-energy region was in good agreement with previous work and the ENDF/B-VII library, except for minor differences. In the high-energy region, however, the relative height of the measured spectrum was greater, and an analysis of the experiment indicated uncertainties of 13% at 10 MeV and 24% at 12 MeV. Experimental results showed that the recoil proton method could be used to measure prompt fission neutron spectra. Some directions for future work are included. 展开更多
关键词 PROMPT FISSION NEUTRON spectra RECOIL PROTON method Response matrix U-235
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A zinc(Ⅱ) MOF based on secondary building units of infinite wavy-shaped chain exhibiting obvious luminescent sense effects
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作者 Kai Li Kunhuan He +3 位作者 Quanwen Li Bin Xia Qinglun Wang Yinghui Zhang 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第2期499-501,共3页
A new metal-organic framework (MOF),{[Zn7 (BPS)4 (OH)6 (H2O)2]·5 H2O]n}(1), (H2 BPS=4,4′-bibenzoic acid-2,2′-sulfone), based on a wavy and infinite chain-shaped secondary building units, has been synthesized un... A new metal-organic framework (MOF),{[Zn7 (BPS)4 (OH)6 (H2O)2]·5 H2O]n}(1), (H2 BPS=4,4′-bibenzoic acid-2,2′-sulfone), based on a wavy and infinite chain-shaped secondary building units, has been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction and further confirmed by PXRD, TGA and IR spectrum. The solid-state emission spectra reveal that compound 1 presents strong luminescence emission bands at room temperature. The fluorescent properties of compound 1 in diverse organic solvents indicated that 1 has palpable luminescent sense effects for DMF and DMAC. 展开更多
关键词 METAL-ORGANIC frameworks Secondary building unit SOLID-STATE emission spectra Fluorescent properties LUMINESCENT SENSE EFFECTS
Site dependent and spatially varying response spectra 预览
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作者 Hakima Djilali Berkane Zamila Harichane +1 位作者 Erkan Celebi Sidi Mohammed Elachachi 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第3期497-509,共13页
The goal of this study is to provide a stochastic method to investigate the eff ects of the randomness of soil properties due to their natural spatial variability on the response spectra spatial variation at sites wit... The goal of this study is to provide a stochastic method to investigate the eff ects of the randomness of soil properties due to their natural spatial variability on the response spectra spatial variation at sites with varying conditions. For this purpose, Monte Carlo Simulations are used to include the variability of both incident ground motion and soil parameters in the response spectra by mean of an appropriate coherency loss function and a site-dependent transfer function, respectively. The approach is built on the assumption of vertical propagation of SH type waves in soil strata with uncertain parameters. The response spectra are obtained by numerical integration of the governing equation of a single-degree-of-freedom (SDOF) system under non-stationary site-dependent and spatially varying ground motion accelerations simulated with non-uniform spectral densities and coherency loss functions. Numerical examples showed that randomness of soil properties signifi cantly aff ects the amplitudes of the response spectra, indicating that as the heterogeneity induced by the randomness of the parameters of the medium increases, the spectral ordinates attenuate. 展开更多
关键词 response SPECTRA RANDOMNESS SPECTRAL density MONTE Carlo
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Effect of site amplifi cation on inelastic seismic response 预览
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作者 Adhikary S Singh Y 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第3期535-554,共20页
The available models for eff ective periods of site and structure are reviewed in context of frequency tuning in the inelastic seismic response of soil-structure system. The eff ect of seismic intensity and ductility ... The available models for eff ective periods of site and structure are reviewed in context of frequency tuning in the inelastic seismic response of soil-structure system. The eff ect of seismic intensity and ductility demand, on the eff ective periods, is investigated, and inelastic site amplifi cation is shown to be strongly correlated to the normalized eff ective period. Two non-dimensional parameters, analogous to the conventional site amplifi cation factors in codes, are defi ned to quantify the inelastic site amplifi cation. It is shown that the inelastic site amplifi cation factor (i.e. ratio of constant ductility spectral ordinates at soil site to those at rock outcrop) is able to represent the site eff ects more clearly, as compared to the inelastic site amplifi cation ratio (i.e. ratio of inelastic spectral ordinates at soil site to the corresponding elastic spectral ordinates at rock outcrop). Further, the peak in the amplifi cation factor corresponding to the eff ective site period diminishes rapidly with increasing ductility demand. 展开更多
关键词 SITE amplifi CATION normalized RESPONSE SPECTRA eff ective period INELASTIC SEISMIC RESPONSE INELASTIC SITE amplifi CATION factor
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关于恒定列和矩阵谱隙的一个估计 预览
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作者 何建锋 《湖北民族学院学报:自然科学版》 CAS 2019年第1期54-58,共5页
通过对恒定列(行)和矩阵性质的讨论,给出一个正恒定列和矩阵谱隙的估计式,该估计式的计算只涉及矩阵元素,计算简便.
关键词 矩阵 特征值 恒定列和
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Absorption Spectra Calculation of Torus-type C120 and Its Nitrogen Doped Derivatives 预览
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作者 范广 周彩华 谢茹玉 《结构化学》 SCIE CAS CSCD 2019年第3期434-438,共5页
The absorption spectra of torus-type C120 and its derivatives doped by nitrogen(C119N, C118N2, C115N5) have been investigated based on the density functional theory. The longest absorption band of torus-type C120 can ... The absorption spectra of torus-type C120 and its derivatives doped by nitrogen(C119N, C118N2, C115N5) have been investigated based on the density functional theory. The longest absorption band of torus-type C120 can arrive at the near IR fields. For three derivatives doped by nitrogen, doped nitrogen atoms can induce the longer absorption band, and the more numbers of nitrogen atoms are doped in torus-type C120, the longer absorption band can be induced. 展开更多
关键词 torus-type C120 photodynamic therapy ABSORPTION SPECTRA
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基于野外实测数据的珊瑚礁不同底质光谱可分性及珊瑚色素影响分析 预览
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作者 徐京萍 李方 +1 位作者 孟庆辉 王飞 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2019年第8期2462-2469,共8页
珊瑚礁遥感监测的任务之一是获取底栖物质的组成及分布,但由于珊瑚礁存在较强的空间异质性及复杂的光谱,使得目前利用遥感技术进行底栖物质信息提取还存在较大难度。珊瑚礁不同底栖物质的光谱特性是开展珊瑚礁遥感监测的基本先验知识,... 珊瑚礁遥感监测的任务之一是获取底栖物质的组成及分布,但由于珊瑚礁存在较强的空间异质性及复杂的光谱,使得目前利用遥感技术进行底栖物质信息提取还存在较大难度。珊瑚礁不同底栖物质的光谱特性是开展珊瑚礁遥感监测的基本先验知识,但目前关于不同珊瑚种类的光谱特性分析研究较为匮乏。本研究基于野外实测光谱数据和模拟卫星遥感数据,开展珊瑚礁不同底质类型的光谱特性研究,特别是针对不同造礁石珊瑚种间及种内的光谱差异进行比较分析,并探讨不同珊瑚体内色素组成对珊瑚光谱特性的影响研究,最后甄选了四种常用卫星数据,通过数值模拟探讨了不同底质类型的光谱可分性。结果显示,利用反射光谱曲线值的大小能较好的识别沙和白化珊瑚,而利用蓝绿红波段反射率的一阶微分值能有效识别出海藻、海草和健康珊瑚。对于不同种类的珊瑚而言,科、属、种、珊瑚形状、珊瑚颜色的不同均会对珊瑚的反射光谱造成影响。叶绿素含量(包含叶绿素a、叶绿素b、叶绿素c)与珊瑚反射光谱值相关性较好,是影响珊瑚光谱反射率的主要因素之一,虫黄藻密度在一定程度上也能影响珊瑚光谱反射率,但不如叶绿素影响明显,其密度的高低会影响珊瑚光谱在局部波段的峰值特征。在目前常用的多光谱卫星数据中, Landsat8数据具有可观测近岸的蓝波段,具备识别沙、白化珊瑚、海藻、健康珊瑚、海草的能力,而IKONOS和Quickbird可识别沙、白化珊瑚和海草。相对而言, SPOT5表现较差,仅能识别沙和白化珊瑚。在不同种类珊瑚的识别方面,多光谱遥感数据由于无法捕捉特征波段,需要采用具有高空间分辨率的高光谱遥感数据进行有效识别。在今后的工作中,将进一步扩大珊瑚礁底质样本数据集,并建立珊瑚礁光谱库,为今后我国珊瑚礁遥感监测体系建立提供数据� 展开更多
关键词 珊瑚礁 光谱 遥感 叶绿素 虫黄藻
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Tracking the reactivity of ozonation towards effluent organic matters from WWTP using two-dimensional correlation spectra
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作者 Xin jin Weijie Zhang +3 位作者 Rui Hou Pengkang Jin Jina Song Xiaochang C.Wang 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期289-298,共10页
The characteristics of effluent organic matter (EfOM) from a wastewater treatment plant (WWTP) during ozonation were investigated using excitation and emission matrix (EEM) spectra, Fourier transform infrared spectros... The characteristics of effluent organic matter (EfOM) from a wastewater treatment plant (WWTP) during ozonation were investigated using excitation and emission matrix (EEM) spectra, Fourier transform infrared spectroscopy (FT-IR) and high-performance size exclusion chromatography (HPSEC) at different ozone dosages. The selectivity of ozonation towards different constituents and functional groups was analysed using two-dimensional correlation spectra (2D-COS) probed by FT-IR, synchronous fluorescence spectra and HPSEC. The results indicated that ozonation can destroy aromatic structures of EfOM and change its molecular weight distribution (MWD). According to 2D-COS analysis, microbial humic-like substances were preferentially removed, and then the protein-like fractions. Terrestrial humic-like components exhibited inactivity towards ozonation compared with the above two fractions. Protein-like substances with small molecular weight were preferentially reacted during ozonation based on 2D-COS probed by HPSEC. In addition, the selectivity of ozone towards different functional groups of EfOM exhibited the following sequence: phenolic and alcoholic CO groups >aromatic structures containing CC double bonds >aliphatic CH. X-ray photoelectron spectroscopy (XPS) further elucidated the preferential reaction of aromatic structures in EfOM during ozonation. 展开更多
关键词 OZONATION TWO-DIMENSIONAL CORRELATION SPECTRA (2D-COS) EFFLUENT organic matter (EfOM) Selectivity
Low-energy(40 keV) proton irradiation of YBa2Cu3O7-x thin films:Micro-Raman characterization and electrical transport properties
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作者 王三胜 李方 +8 位作者 吴晗 张玉 穆罕默德苏尔曼 赵鹏 乐小云 肖志松 姜利祥 欧学东 欧阳晓平 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第2期406-413,共8页
To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiate... To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa2Cu3O7-x(YBCO) thin films are carried out. From micro-Raman spectroscopy and x-ray diffraction studies, the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase. The results indicate that the defects induced in the conducting CuO2 planes, such as increased oxygen vacancies and interstitials, can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation, which is confirmed in the electrical transport measurements. Especially, zero-resistance temperature TC0 is not observed at a fluence of 1015p/cm2.Furthermore, the variation of activation energy U0 can be explained by the plastic-flux creep theory, which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects. Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films. These disorders are likely to cause flux creep by thermally assisted flux flow, which may increase noise and reduce the precision of superconducting devices. 展开更多
关键词 SUPERCONDUCTORS PROTON radiation MICRO-RAMAN spectra electrical transport
A revised jump-diffusion and rotation-diffusion model
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作者 李华 陈昱沆 唐宾泽 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期216-221,共6页
Quasi-elastic neutron scattering (QENS) has many applications that are directly related to the development of highperformance functional materials and biological macromolecules,especially those containing some water.T... Quasi-elastic neutron scattering (QENS) has many applications that are directly related to the development of highperformance functional materials and biological macromolecules,especially those containing some water.The analysis method of QENS spectra data is important to obtain parameters that can explain the structure of materials and the dynamics of water.In this paper,we present a revised jump-diffusion and rotation-diffusion model (rJRM) used for QENS spectra data analysis.By the rJRM,the QENS spectra from a pure magnesium-silicate-hydrate (MSH) sample are fitted well for the Q range from 0.3A^-1 to 1.9A^-1 and temperatures from 210 K up to 280 K.The fitted parameters can be divided into two kinds.The first kind describes the structure of the MSH sample,including the ratio of immobile water (or bound water) C and the confining radius of mobile water a0.The second kind describes the dynamics of confined water in pores contained in the MSH sample,including the translational diffusion coefficient Dt,the average translational residence time τ0,the rotational diffusion coefficient Dr,and the mean squared displacement (MSD){u^2}.The rJRM is a new practical method suitable to fit QENS spectra from porous materials,where hydrogen atoms appear in both solid and liquid phases. 展开更多
关键词 revised JUMP-DIFFUSION and rotation-diffusion model (rJRM) data analysis of quasi-elastic neutron scattering (QENS) spectra dynamics of water magnesium-silicate-hydrate (MSH) samples
宽气压下介质阻挡放电等离子体激励器放电特性
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作者 杨磊磊 康磊 蔡晋生 《高电压技术》 EI CAS CSCD 北大核心 2019年第3期790-798,共9页
为适应飞行器在高空宽气压环境下的等离子体流动控制,基于典型构型的介质阻挡放电等离子体激励器(dielectric barrier discharge plasma actuator,DBDPA)在不同气压下的静止大气放电实验,研究了气压对DBDPA放电的起始放电电压、辉光形... 为适应飞行器在高空宽气压环境下的等离子体流动控制,基于典型构型的介质阻挡放电等离子体激励器(dielectric barrier discharge plasma actuator,DBDPA)在不同气压下的静止大气放电实验,研究了气压对DBDPA放电的起始放电电压、辉光形态、光谱特性、伏安特性、放电功率、诱导气流的时均反推力和时均速度等的影响特性。研究结果表明:随着气压的逐渐下降(从0.1 MPa降至0.02 MPa),DBDPA的起始放电电压逐渐降低(从6.4kV降至2.8 kV),放电辉光逐渐增强,辉光区域逐渐变大(从约2 mm增到15 mm);光谱特征谱线位置不变,光谱强度增加;电流幅值和微放电电流脉冲逐渐增强;放电功率单调增加,并在0.06 MPa以下阶段呈现陡增;诱导气流的时均速度整体上单调增加;而时均反推力先增加后减少,存在峰值气压,随着驱动电压峰值从12 kV增加至16 kV,峰值气压从0.04 MPa增至0.06 MPa。另外,诱导气流的时均反推力和时均速度与驱动电压和频率均成正比。在特定的低气压0.05 MPa下,DBDPA的放电功率与驱动电压成正比,而随着驱动频率的增加,放电功率先增加后减少,存在峰值频率3.5 kHz。 展开更多
关键词 介质阻挡放电 宽气压 放电功率 光谱特性 反推力 诱导速度
Molecular Spectra and Dissociation Dynamics of Oxalyl Chloride: Effect of External Electrical Fields 预览
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作者 尹文怡 刘玉柱 +1 位作者 周冯斌 布玛丽亚·阿布力米提 《结构化学》 SCIE CAS CSCD 2019年第4期499-508,共10页
Oxalyl chloride is a highly toxic and caustic substance, which widely exists in human production and life as a kind of volatile organic compound. Based on the density functional theory B3 LYP at 6-311++G(d, p) level, ... Oxalyl chloride is a highly toxic and caustic substance, which widely exists in human production and life as a kind of volatile organic compound. Based on the density functional theory B3 LYP at 6-311++G(d, p) level, the influences of external electric field on the bond length, bond energy, dipole moment and dissociation mechanism are optimized. The results indicate that the C1–Cl3 bond length increases while the C4–Cl6 bond decreases. At the same time, the carbon-carbon bond length gradually increases with the increase of electric field. The total energy decreases while the dipole moment gradually increases with the increase of electric field. In the infrared spectra, the vibration frequency of the carbon-chlorine(C4–Cl6) bond decreases while the vibration frequency of the carbon-oxygen bond increases. In the ultraviolet-visible spectra, the wavelength of the strongest absorption peak increases as the external electric field increases and shows an observable red shift phenomenon. Additionally, single point energies of oxalyl chloride along the carbon-carbon bond are scanned with the equation-of-motion coupled cluster method restricted to single and double excitations(EOM-CCSD) method and the potential energy curves under different external electric fields are obtained. The dissociation barrier in potential energy curve decreases because of the breakage of carbon-carbon bond with the increase of external electric field. These results provide reference for further researches on the properties of oxalyl chloride and offer a theoretical basis for the study of oxalyl chloride degradation. 展开更多
关键词 oxalyl CHLORIDE SPECTRA electric field DENSITY FUNCTIONAL theory DEGRADATION
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Calculation of the wide-angle neutron spectra from the 9Be(d,xn) reaction in a thick beryllium target
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作者 韦峥 王俊润 +11 位作者 张雅玲 黄智武 马占文 张杰 丁琰琰 夏莉 李建一 卢小龙 张宇 徐大鹏 杨磊 姚泽恩 《中国物理C:英文版》 SCIE CAS CSCD 2019年第5期29-34,共6页
The multi-layer computing model is developed to calculate wide-angle neutron spectra, in the range from0° to 180° with a 5° step, produced by bombarding a thick beryllium target with deuterons. The doub... The multi-layer computing model is developed to calculate wide-angle neutron spectra, in the range from0° to 180° with a 5° step, produced by bombarding a thick beryllium target with deuterons. The double-differential cross-sections(DDCSs) for the 9 Be(d, xn) reaction are calculated using the TALYS-1.8 code. They are in agreement with the experimental data, and are much better than the PHITS-JQMD/GEM results at 15°, 30°, 45° and 60° neutron emission angles for deuteron energy of 10.0 MeV. In the TALYS-1.8 code, neutron contributions from direct reactions(break-up, stripping and knock-out reactions) are controlled by adjustable parameters, which describe the basic characteristics of typical direct reactions and control the relative intensity and the position of the ridgy hillock at the tail of DDCSs. It is found that the typical calculated wide-angle neutron spectra for different neutron emission angles and neutron angular distributions agree quite well with the experimental data for 13.5 MeV deuterons. The multi-layer computing model can reproduce the experimental data reasonably well by optimizing the adjustable parameters in the TALYS-1.8 code. Given the good agreement with the experimental data, the multi-layer computing model could provide better predictions of wide-angle neutron energy spectra, neutron angular distributions and neutron yields for the 9 Be(d, xn) reaction neutron source. 展开更多
关键词 NEUTRON source 9Be(d xn) REACTION THICK TARGET WIDE-ANGLE NEUTRON spectra NEUTRON angular distributions
Floristic composition and ecological gradient analyses of the Liakot Forests in the Kalam region of District Swat,Pakistan 预览
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作者 Sohail Anwar Shujaul Mulk Khan +2 位作者 Zeeshan Ahmad Zahid Ullah Majid Iqbal 《林业研究:英文版》 CAS CSCD 2019年第4期1407-1416,共10页
Kalam Kohistan is a dry,temperate hilly region in the Hindu Raj Series of the Greater Hindu Kush Mountains with diverse forests.As plant distribution and composition is expression of a range of various environmental v... Kalam Kohistan is a dry,temperate hilly region in the Hindu Raj Series of the Greater Hindu Kush Mountains with diverse forests.As plant distribution and composition is expression of a range of various environmental variables,ecological and floristic attributes of vegetation in the Laikot Forests were therefore evaluated via consecutive explorative trips.These forests have not been evaluated ecologically before due to harsh climatic conditions and issues of accessibility and the study in hand is one of the first in its nature.Quantitative ecological techniques were used to sample forest vegetation and identify species in quadrats of 2 m×2 m for herbs,5 m×5 m for shrubs and 10 m×10 m for trees.All the data of 195 plant species and environmental factors were analyzed via Two-way Cluster Analysis and Canonical Correspondence Analysis using PCORD and CANOCO software.Among 195 plant species from 63 families were 27 species of Asteraceae,the most-speciose family,followed by Poaceae(20 spp.).The dominant life form was therophyte(86 spp.;44%share),followed by phanerophyte(41 spp.;21%share).For the leaf size spectrum,most prevalent was nanophyll(73 spp.;44%)followed by microphyll(66 spp.,34%)and mesophyll(44 spp.;23%).Calcium carbonate,pH,potassium,sand,silt,organic matter,slope aspect and grazing significantly influenced species composition,distribution and habitat.The floristic variation in the region was diverse due to elevational and aspect gradients and thus devided into three zones.This vegetation zonation can be utilized for forest management,species and habitat conservation.Both in situ and ex situ conservation of threatened plant species may improve their conservation status in future if address properly. 展开更多
关键词 FLORISTIC composition Ecological factors Life FORM spectra Leaf FORM classes Elevation ZONES CANONICAL CORRESPONDENCE analysis(CCA)
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半正则混合图的线图的谱 预览
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作者 谢玲燕 晏卫根 《厦门大学学报:自然科学版》 CAS CSCD 北大核心 2019年第3期387-390,共4页
给一个无向图的某些边定向得到的图称为混合图,它可能既存在无向边又存在有向边.一个无向半正则图 G 的线图 l(G)的邻接谱完全由 G 的邻接谱确定.主要推广了前面这个结果,证明了半正则混合图 G 的线图 l(G)的H-邻接谱完全由混合图 G 的H... 给一个无向图的某些边定向得到的图称为混合图,它可能既存在无向边又存在有向边.一个无向半正则图 G 的线图 l(G)的邻接谱完全由 G 的邻接谱确定.主要推广了前面这个结果,证明了半正则混合图 G 的线图 l(G)的H-邻接谱完全由混合图 G 的H-邻接谱确定. 展开更多
关键词 混合图 半正则图 线图 H-邻接矩阵
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Removing Moisture Effect on Soil Reflectance Properties: A Case Study of Clay Content Prediction
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作者 Yaron OGEN Shira FAIGENBAUM-GOLOVIN +3 位作者 Amihai GRANOT Yoel SHKOLNISKY Naftaly GOLDSHLEGER Eyal BEN-DOR 《土壤圈:英文版》 SCIE CAS CSCD 2019年第4期421-431,共11页
Visible, near-infrared and shortwave-infrared(VNIR-SWIR) spectroscopy is an efficient approach for predicting soil properties because it reduces the time and cost of analyses. However, its advantages are hampered by t... Visible, near-infrared and shortwave-infrared(VNIR-SWIR) spectroscopy is an efficient approach for predicting soil properties because it reduces the time and cost of analyses. However, its advantages are hampered by the presence of soil moisture, which masks the major spectral absorptions of the soil and distorts the overall spectral shape. Hence, developing a procedure that skips the drying process for soil properties assessment directly from wet soil samples could save invaluable time. The goal of this study was twofold:proposing two approaches, partial least squares(PLS) and nearest neighbor spectral correction(NNSC), for dry spectral prediction and utilizing those spectra to demonstrate the ability to predict soil clay content. For these purposes, we measured 830 samples taken from eight common soil types in Israel that were sampled at 66 different locations. The dry spectrum accuracy was measured using the spectral angle mapper(SAM) and the average sum of deviations squared(ASDS), which resulted in low prediction errors of less than 8% and 14%, respectively. Later, our hypothesis was tested using the predicted dry soil spectra to predict the clay content, which resulted in R^2 of 0.69 and 0.58 in the PLS and NNSC methods, respectively. Finally, our results were compared to those obtained by external parameter orthogonalization(EPO) and direct standardization(DS). This study demonstrates the ability to evaluate the dry spectral fingerprint of a wet soil sample, which can be utilized in various pedological aspects such as soil monitoring, soil classification,and soil properties assessment. 展开更多
关键词 dry SPECTRAL FINGERPRINT nearest NEIGHBOR SPECTRAL correction partial least SQUARES reflectance spectra SOIL MOISTURE SOIL property spectroscopy wet SOIL
Measurement of interfacial residual stress in SiC fiber reinforced Ni-Cr-Al alloy composites by Raman spectroscopy
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作者 Xixi Niu Haoqiang Zhang +3 位作者 Zhiliang Pei Nanlin Shi Chao Sun Jun Gong 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第1期88-93,共6页
Raman spectroscopy was used to measure Raman spectra of the inner SiC fibers and surface C-rich layers of SiC fibers, composite precursors and SiCf/Ni-Cr-Al composites. The residual stresses of the inner SiC fibers an... Raman spectroscopy was used to measure Raman spectra of the inner SiC fibers and surface C-rich layers of SiC fibers, composite precursors and SiCf/Ni-Cr-Al composites. The residual stresses of the inner SiC fibers and surface C-rich layers were calculated, and the effect of the(Al + Al2O3) diffusion barrier layer on the interfacial residual stress in the composites was analyzed in combination with the interface microstructure and energy disperse spectroscopy(EDS) elements lining maps. The results show that the existence of(Al + Al2O3) diffusion barrier improves the compatibility of the SiCf/Ni-Cr-Al interface,inhibits the adverse interfacial reaction, and relieves the residual stress inside SiC fibers and at the interface of composite material. Heat treatment can reduce the residual stress at the interface. As the heat treatment time increases, the residual stress at the interface decreases. 展开更多
关键词 NI-CR-AL alloy SiC fiber Composite Raman spectra Diffusion barrier coating Residual stress
油墨红外光谱相似度与计算机配色精度的关系研究 预览
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作者 万星 吕新广 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2019年第3期711-716,共6页
为了获得高精度的配色样品,提出了一种配色方法-成分分析配色法。该方法将化学分析法与计算机配色相结合,其核心是选取与目标色成分最接近的油墨进行配色,从而实现高精度的色彩匹配,为计算机配色发展提供新的思路。与目标色成分相近的... 为了获得高精度的配色样品,提出了一种配色方法-成分分析配色法。该方法将化学分析法与计算机配色相结合,其核心是选取与目标色成分最接近的油墨进行配色,从而实现高精度的色彩匹配,为计算机配色发展提供新的思路。与目标色成分相近的油墨配色效果验证:使用某种油墨印制目标色,并用相同的油墨进行配色,以实现目标色成分与配色色样成分的一致性。使用三个不同品牌的油墨对目标色进行配色,比较配色精度及效率。使用泗联牌三种颜色油墨以任意比例通过印刷适性仪IGT-CI(荷兰)印制目标色,这些目标色包括间色和复色,各3个色样;使用配色软件X-Rite color master(美国)建立泗联、东洋、牡丹三个品牌油墨的配色基础数据库,并对不同目标色进行配色。结果表明使用与目标色相同的泗联油墨的配色精度远高于东洋、牡丹两个品牌的油墨,配色色差整体都很小,校正1~2次就能得到小于1.0的色差,最小达到0.36,几乎实现了目标色的同色同谱匹配。实验验证了成分分析配色法的核心"选取与目标色成分最接近的油墨进行配色,可以实现高精度色彩匹配"的可行性。判别目标色与配色油墨在成分上区别的化学分析工具探讨:为了判别目标色色料与配色油墨在成分上有区别,尝试使用"红外光谱相似度"作为判别的分析工具。使用红外光谱仪Thermo Nicolet 6700(美国)测出泗联、东洋、牡丹三个品牌的三种颜色油墨的红外光谱图,使用OMNIC软件中的相关性算法得到它们与目标色油墨的红外光谱相似度,并计算出平均相似度;将各品牌油墨的红外光谱相似度与其配色实验的精度进行对比分析,评价红外光谱相似度作为化学分析判别工具的有效性。结果表明泗联牌油墨与目标色的平均红外光谱相似度为100%,东洋的为86.53%,牡丹的为64.63%。当校正次数相同时,泗联油墨配色色差最 展开更多
关键词 计算机配色 油墨 色差 光谱
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