竞租函数与城市土地利用

本文概述了单中心城市的企业（如制造商、办公业、零售商店）竞租函数和住宅竞租函数；分析了单中心城市的竞租函数与土地利用之间的关系；并对影响竞租函数的几个重要因素加以阐述。     

人工成孔夯实碎石桩复合地基承载力分析

依据工程实例，分析了人工成孔夯实碎石桩加固天然地基的P—s，s—lgt曲线，得出了不同桩间距对加固天然地基的复合地基承载力的影响效果，总结了人工成孔夯实碎石桩的应用优点。     

Variation of LiNiO<Subscript>2</Subscript> cathode properties with substitution of Ga,In and Tl by the combustion method

LiNi_1-y M_yO₂ (M = Ga, In and Tl, y = 0.010, 0.025 and 0.050) with small y were synthesized by the combustion method by calcining in an O₂ stream at 750 °C for 36 h. XRD analyses, SEM observation and measurement of the variation of discharge capacity with the number of cycles were carried out. All the samples had the Rm structure and LiNi_1-y In _y O₂ contained LiInO₂ phase as an impurity. Among LiNi_1-y Ga _y O₂ the sample with y = 0.025 had a relatively large first discharge capacity (172.2 mAh g⁻¹) and relatively good cycling performance (discharge capacity 140.3 mAh g⁻¹ at n = 20). For LiNi_0.975M_0.025O₂ (M = Ga, In and Tl), the first discharge capacity decreased in the order of the substituted element Ga, In and Tl. The variations of cation mixing and hexagonal ordering with the substituted element (decrease in I₀₀₃/I₁₀₄ and increase in R-factor from M = Ga through M = Tl) are considered to lead to the behavior of the first discharge capacity with the substituted element. LiNi_0.975Tl_0.025O₂ had the smallest degradation rate of the discharge capacity.     

考虑价格型需求响应的独立型微电网优化配置

为有效提高独立型微电网可再生能源消纳水平,根据独立型微电网内短期风光出力与负荷之间的供需关系提出一种动态分时电价机制,并基于替代弹性建立价格型需求响应模型;从经济性角度出发,计及电价引导下用户的用电行为,建立价格型需求响应参与的独立型微电网的优化配置模型,并采用遗传算法求解。以某海岛微电网为例进行仿真分析,算例结果表明:在独立型微电网优化配置中考虑价格型需求响应能够改善负荷特性,提高可再生能源的配置容量,减少储能和燃料发电机的使用,从而提高微电网的经济性。     

Synthesis and characterization of rare-earth elements substituted Ni-Zn ferrites

ABSTRACT

The spinel Ni_0.7Zn_0.3RE_0.04Fe_1.96O₄ ferrites with RE?Ce and Y are fabricated by the polyacrylamide gel method. The effect of rare earth ions substitution for iron ions on the structure, morphology, electromagnetic and microwave-absorbing properties of Ni-Zn ferrites are investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetric and differential thermal analysis (TG-DTA) and HP8510B network analyzer, respectively. The results indicate that Ni_0.7Zn_0.3RE_0.04Fe_1.96O₄ ferrites form a pure cubic spinel structure, and Ce³⁺ and Y³⁺ substitute into the crystal lattice. Both the real ?′ and imaginary ?″ parts values of complex permittivity for Ni_0.7Zn_0.3RE_0.04Fe_1.96O₄ ferrites are higher than those for Ni-Zn ferrites in X-band (8.2-12.4 GHz) frequency range. When RE ions substitute for iron ions, the real μ′ and imaginary μ″ parts values of complex permeability for Ni_0.7Zn_0.3RE_0.04Fe_1.96O₄ ferrites decrease and increase, respectively. The microwave-absorbing properties are better for RE-substituted Ni-Zn ferrites than Ni-Zn ferrites. For Ni_0.7Zn_0.3Ce_0.04Fe_1.96O₄ ferrites, the minimum loss is ?12.5 dB at 18 GHz for an absorber thickness of 2 mm.     

An Unexpected Potassium Iodide‐Promoted Nucleophilic Substitution Reaction between 2‐Acyloxy‐2H‐azirines and Carboxylic Acids

The acyloxy group of 2‐acyloxy‐2H‐azirines has been displaced by carboxylic acids to generate the corresponding 2‐acyloxy‐2H‐azirines by using potassium iodide as a promotor. This metal‐free method can be performed with a wide scope of substrates readily generating products in moderate to high yields. It also represents an example of nucleophilic substitution between esters and carboxylic acids under metal‐free reaction conditions for the first time.

     

含Sm和Cr的P型FeSi2基热电材料的电学特性

通过高温悬浮熔炼法制备含Sm、Cr的P型FeSi2基热电材料Fe1-x-ySmxCrySi2，进行电学性能的测试和研究。实验结果，表明Fe1-x-ySmxCrySi2的输运特性是由两种掺杂元素共同作用所决定的,Sm对电阻率的变化影响较大，而Cr的掺入能提高高样品的热电动热率。为提高材料的电学性能，Cr的最佳掺杂原子数在3．33％左右，而Sm的含量应小于3．33％，通过Sm,Cr的适当掺杂，可得到电学性能优良的FeSi基热电材料。     

z值影响Sm(CoFeCuZr)z磁性能的机理研究

通过粉末冶金法制备了不同z值(z=7.5～8.5)的Sm(CoFeCuZr)_z磁体。利用磁性能测量系统、X射线衍射分析、电子探针以及透射显微镜等对磁体的性能、组成相、析出相含量、微观结构及元素分布进行表征,通过分析解释了磁性能随z值变化的内在机理。结果表明:随z值增大,胞状结构尺寸增大,高饱和磁化强度的2:17R相增多导致剩磁Br升高;z值增大导致富Zr析出相增多,引起方形度H_k/H_(cj)下降;z值通过改变Cu元素在2:17R相界面位置的富集程度来改变矫顽力H_(cj)的大小,在一定范围内(z8.2)该位置Cu含量越高,矫顽力越大。     

河北沧县深部盐矿勘探孔盐水泥浆技术

在沧县石盐矿普查的施工中,ZK001勘探孔终孔深度3451m,裸眼段长度达2950m,由于大段连续取心钻进,施工时间大幅增加,对泥浆护壁技术提出挑战。根据地层特征在节约成本的前提下,施工中分别使用了淡水泥浆与盐水泥浆,特别是取心过程中,盐水泥浆护壁起到很好的效果。本文主要介绍了淡水泥浆—盐水泥浆转换需要注意的问题和盐水泥浆的特点与应用。通过施工检验,盐水泥浆性能稳定,易于维护,有效控制了地层坍塌、缩径等复杂问题,保证了钻进安全,适合工区应用。     

Sm2Co17型永磁合金时效处理的显微结构与内禀矫顽力

采用扫描电子显微镜(SEM)结合X射线能谱仪(EDS)对Sm2Co17型钐钴永磁合金时效处理过程中的显微结构与成分的变化进行分析,揭示该类永磁合金的显微结构在时效过程中随着时效温度和时间的改变而变化的规律,明确正常样品的典型显微结构SEM照片。此方法较光学显微镜的显微结构结果更加准确直观,较透射电子显微镜则有制样简单和分析快速的特点,在产品质量控制中应用效果显著。