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771.
为探讨蓝绿基础设施(Blue-Green Infrastructure,BGI)碳汇服务功能有益于指引城市碳中和目标建设,本研究以广西北部湾海岸带城市为例,运用形态学空间格局分析(Morphological Spatial Pattern Analysis,MSPA)法、连通性分析法以及电路理论,构建蓝绿基础设施碳汇网络,讨论对应的固碳增汇对策。结果表明:2020年研究区蓝绿空间碳汇总量为735 524.09 tC·a-1,其中绿色空间碳汇总量为588 680.06 tC·a-1,蓝色空间碳汇总量为146 844.03 tC·a-1,单位面积碳汇量“蓝”高于“绿”;共提取63个碳汇源地斑块,20个核心源地斑块,绿色空间核心源地总面积为6 814.31 km2,蓝色空间为899.05 km2,核心源地主要分布在东西两侧及南部沿海地带;共提取出24条生态廊道,绿廊共长122.21 km,蓝廊为52.75 km,呈环状分布,中南部地区分布较密,连通性强。本研究结果可为“碳达峰与碳中和”(简称“双碳”)背景下海岸带城市的保护与可持续发展提供建设思路。 相似文献
772.
《Discrete Mathematics》2022,345(2):112685
Investigating (periodic) and design sequences with good correlation properties have numerous applications in communications. Research on designing sequence pairs with good correlation properties started in the early 1950's thanks to M.J. Golay. Ideally, one of our ultimate aims in this context is to design a set of sequences whose out-of-phase auto-correlation magnitudes and cross-correlation magnitudes are very small, preferably zero. The so-called Z-complementary pair (ZCP) is one of the suitable candidates. A pair of sequences is called a Z-complementary pair (ZCP) if it has zero aperiodic autocorrelation sums (AACSs) for time-shifts within a certain region, called zero correlation zone (ZCZ). ZCPs have been widely used in different communication systems and are closely related with almost difference families, which are useful in studying partially balanced incomplete block design. Despite remarkable progress in designing ZCPs, only a few constructions of quadriphase ZCPs (QZCPs) have been reported in the literature up to now. Aiming to reducing this gap, we explore in this article several methods to design such sequences. More specifically, we propose a recursive construction based on the concatenation of sequences aimed to design Type-II QZCPs. Also, based on Turyn's construction method, we present another new Type-II QZCPs. The proposed constructions lead to Z-optimal Type-II even-length QZCPs (E-QZCPs) and Type-II odd-length QZCPs (O-QZCPs) with large ZCZ widths. Finally, we derive upper bounds for the peak-to-mean envelope-power ratio (PMEPR) of the proposed ZCPs. It turns out that our constructions lead to ZCPs with low PMEPR. These characteristics allow our QZCPs to be seen as promising for practical uses in some modern communication systems. 相似文献
773.
Qian Guan Yong Liu Bo Ling Guisheng Zeng Haiyan Ji Jiefei Zhang Qiang Zhang 《国际化学动力学杂志》2020,52(7):463-471
Sodium arsenate, the main component of arsenic-containing solid waste pollutants, causes serious environmental health threats. Crystallization is one of the effective methods for separating and purifying sodium arsenate from arsenic-alkali residue lixivium. However, the crystallization process is limited for its low observability and the lack of separation and purification data. In this work, a laser detection system with a magnetic field generator was designed, and the solubility, metastable zone width, interfacial tension, interfacial entropy factor, crystal nucleation, and growth rate of sodium arsenate were investigated in a constant composition environment. The results showed that the solubility, metastable zone width, interfacial tension, and interfacial entropy factor decreases with the presence of a magnetic field. The magnetic field shortened the crystallization induction time and changed the nucleation and growth rate of sodium arsenate. Under the magnetic field, the nucleation rate increased from 2.43 × 1016 to 8.98 × 1017 (s m3)−1, and the growth rate decreased from 4.94 × 10−8 to 2.73 × 10−8 (s m3)−1, the growth mechanism of sodium arsenate as a continuous growth mode was unchanged. In addition, the X-ray diffraction and infrared showed that the crystal structure of sodium arsenate is unaffected by the magnetic field, indicating that the enhancement of the crystallization process of sodium arsenate with the magnetic field could be a feasible method in engineering application. 相似文献
774.
Migration of salts in the unsaturated zone caused by heating 总被引:3,自引:0,他引:3
Heat-transfer phenomena as well as moisture movement in unsaturated soils due to thermal gradients, have been extensively studied during the last four decades. Less attention has been devoted to the transport and redistribution of solutes caused by heating.Solar radiation, radioactive waste repositories, underground energy storage, buried electric cables and steam pipes, disposal of waste heat from power plants are examples of heat sources in the soil.Soil-water properties, such as surface tension, viscosity, density, as well as the equilibrium composition of phases, depend on temperature. Hence, nonuniform heating of a soil partially saturated by saline water has an effect on such processes as water flow under capillary and gravitational forces, evaporation, condensation and diffusion of vapor and transport and precipitation of salts.A mathematical model is presented for the migration of salts in the vadoze zone in the soil under nonisothermal conditions, taking into account the above-mentioned phenomena. The physical assumptions underlying the model are briefly discussed.The study of a particular case shows that under certain conditions, a heat source may attract dissolved salts, and cause their precipitation in the hot area. 相似文献
775.
The results of the impedance spectroscopy measurements on eutectic samples based on zirconium oxide are presented here. Samples of CaZrO3---ZrO2(cubic) and MgO---ZrO2(cubic) have been grown by a directional solidification procedure such that the different phases appear nearly oriented along the growth direction (lamellae in the system of CaZrO3-ZrO2(cubic) and fibers of MgO in a ZrO2 matrix in the other system). The DC electrical conductivity has been measured by impedance spectroscopy along and across the growth axis. For CaZrO3---ZrO2 the coductivity is clearly anisotropic. The following values for σT have been obtained: the conductivity at 600 °C equals 2.0 × 10−6 Ω−1 cm−1 perpendicular to the fiber axis and 1.4 × 10−5 Ω−1 cm−1 parallel to it and with an activation energy of 1.3 eV for σT. For MgO---ZrO2(cubic) the isotropic value of the conductivity at 600 °C is 10−4 Ω−1 cm−1 with activation energy for σT of 1.5 eV. The anisotropic conductivity in the CaZrO3---ZrO2 (cubic) system has been explained by a model of an ordered stacking of oxygen conducting (cubic ZrO2) and non-conducting (CaZrO3 or MgO) phases. 相似文献
776.
于竞敏 《黑龙江科技学院学报》1994,(1)
超声波探测技术是煤矿生产中测试煤体、岩体和混凝土工程内部结构特征和受力状态的有效方法之一,本文阐述了在实验室和煤矿现场经常采用的一些测试方法和在实际工程中的应用。 相似文献
777.
DISCOVERY OF GIGANTIC EARLY CAMBRIAN FOSSIL ZONE AND DISINTEGRATION OF INNER MONGOLIA EARTH AXIS 总被引:1,自引:0,他引:1
《科学通报(英文版)》1990,35(23):1975-1975
778.
779.
利用红外光源浮区法生长出大尺寸、高质量的磁失措自旋冰化合物Dy2Ti2O7单晶体.X射线衍射实验证实晶体具有面心立方结构,空间群为Fd3m,晶胞参数a=1.0112(2) nm,[111]和[400]方向X射线衍射摇摆曲线半高宽分别仅为0.07°和0.05°.直流磁化率与温度关系测量给出晶体的Van Vleck顺磁因子为2.46×10-5 m3/mol,有效磁矩μeff=10.24(4)μB,Cure-Weiss温度ΘCW=1.1 K,揭示Dy2Ti2O7具有弱的铁磁性.对磁性起源的综合分析表明,该自旋冰晶体磁性质主要来源于磁偶极相互作用,且相关最近邻长程偶极相互作用能量标度Dnn=3.00 K.
关键词:
2Ti2O7')" href="#">Dy2Ti2O7
浮区法晶体生长
关联电子系统
自旋冰 相似文献
780.
L. Montagnon F. Spiegelman 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):7-10
We illustrate the influence of the thermalization of electrons on the linear-cyclic isomerization of small carbon clusters
by model Monte Carlo calculations of C3
+ at 3500 K. It is shown that the inclusion of the electronic degrees of freedom, in such systems with several low-lying excited
states, can significantly change the relative isomer populations and energy distributions, as compared with equivalent electronic
ground-state simulations. 相似文献