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Search Results: 1 - 10 of 50002 matches for " 秦卫阳 "
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城市空间相互作用理论模型的演进与机理
,|王发曾|耀辰
地理科学进展 , 2009, DOI: 10.11820/dlkxjz.2009.04.005
Abstract: 城市空间相互作用理论是城市地理学的重要基础理论。由于城市空间相互作用模型发端于西方,我国这方面的研究相对较晚,主要是引进和实证,在理论研究上还有待深入。本文分析了几种主要城市空间相互作用理论模型的机制和原理,考虑到断裂点模型应用较广,经过了较多的实践验证,重点探讨了该模型的缺陷、演进和扩展形式,从理论上论证了将空间分割原理和断裂点模型结合的扩展模型的科学性和合理性。对城市空间相互作用理论模型的研究,不仅可以为城市规划、城市影响空间和城市经济区的划分以及行政区划调整提供理论基础,而且对物流分析、设施选址、市场影响力的分析等也具有重要的指导作用。从分析城市空间相互作用理论模型演进的过程中还可以得到深刻的启发地理学以复杂的自然、人文现象为研究对象,是一门边缘学科,又是一门实践性很强的学科。地理学应积极借鉴其他学科最新的理论、技术与方法是十分必要的,是推动其自身发展的关键所在。
含铷固体超强碱Rb2O/γ-Al2O3的制备及其催化酯交换反应研究
,明高,刘世明
- , 2015,
Abstract: 以从盐湖卤水中提取的RbCl为原料,利用原位法和浸渍法制备了含铷的固体超强碱Rb2O/γ-Al2O3.以蔗糖为模板剂,以Rb2CO3及Al(NO3)3为反应物,原位法制备了Rb2O/γ-Al2O3.同时以蔗糖为模板剂,先分别以Al(NO3)3和异丙醇铝(Al\[CH(CH3)2\]3)为铝源制备了介孔γ-Al2O3,再通过浸渍RbNO3溶液,制备了一系列的负载型Rb2O/γ-Al2O3.通过优化制备条件,两种方法制备的Rb2O/γ-Al2O3的碱强度均可达26.5以上,即为超强碱.把制备的超强碱Rb2O/γ-Al2O3用于三醋酸甘油酯和甲醇为模型反应物模拟生物柴油制备过程中的催化酯交换反应.得到了最佳的催化反应条件:原料醇酯比8∶1,反应温度338 K,反应时间4 h,催化剂用量w三醋酸甘油酯=6.0%,在此工艺条件下乙酸甲酯产率达98%以上.
Solid superbases Rb2O/γ-Al2O3were prepared from rubidium salts separated from salt brine. Sucrose was used as the template, Rb2CO3 (prepared from RbCl) and Al(NO3)3 as the raw materials, we prepared Rb2O/γ-Al2O3 successfully by using in-situ method. In impregnation method, we first used sucrose as the template, Al (NO3)3 and Al[CH(CH3)2]3 as aluminum sources, respectively to prepare γ-Al2O3,and then a series of Rb2O/γ-Al2O3 with different rubidium contents through the impregnation of RbNO3 (prepared from RbCl). The base strength of Rb2O/γ-Al2O3 both can reach 26.5 or more, belonging to superbase prepared through the two methods by controlling the conditions. The prepared Rb2O/γ-Al2O3 solid superbases were used to simulate interesterification in the process of producing biodiesel by catalyzing triglycerides acetate and methanol. The optimum reaction conditions were as follows: the ratio of alcohol to ester was 8∶1, the reaction temperature was 338 K, the reaction time was 4 h, and the amount of catalyst is 6.0% of the weight of ester. Under those conditions, the productivity of methyl acetate was up to 98%.
转子系统在随机扰动下的动力学同步控制方法
Dynamical Synchronization between Rotors and its Stability Control under Stochastic Disturbance

孙涛,,向欢,王元生
- , 2017,
Abstract: 多转子系统在运行过程中,往往需要保持各个转子的运动同步,以达到最佳的性能与输出效果。对于转子系统,设计了一种以支承响应作为输入的控制方法,实现了两个转子系统之间的完全同步。这种同步,在支承受到随机干扰和故障产生的脉冲干扰下,仍然能够保持很好的稳健性。首先对同步控制方法进行了理论分析与证明,然后以弹性支承悬臂转子为对象,进行了仿真验证。模拟实际基础激励,在支承处施加随机与脉冲载荷,仿真结果证明了同步的稳定性,并且达到了很高的精度。
In this paper we addressed the dynamical synchronization between rotors and its robustness for random and pulse disturbances. For a dual-rotor system, we present a control method to realize synchronization between the rotors, which only needs the dynamic response of an elastic support of a rotor. The control method for synchronization by support coupling is proved theoretically. For validation an overhung rotor with two elastic supports were simulated. To examine the robustness of the method, additional pulse and stochastic disturbance forces are exerted on one of the two supports respectively. The results show that the simulation system will reach synchronization with the rotor rapidly. The responses of supports and disks prove that a high accuracy can be attained even under disturbances
国外低碳城市研究进展
耀辰,张丽君,鲁丰先,,王喜
地理科学进展 , 2010, DOI: 10.11820/dlkxjz.2010.12.001
Abstract: 在人类应对全球气候变化的挑战中,低碳城市逐渐成为低碳经济与低碳社会的空间聚焦点。文章从城市碳排放驱动因素、低碳城市循环与代谢、低碳城市空间规划、低碳城市环境管治等四方面系统归纳了国外低碳城市研究的内容和模型方法,并对LMDI方法、Hybrid-EIO-LCA方法、CGE模型作了具体评述。可以认为,低碳城市研究在理论上,由可持续发展、循环经济转向低碳经济和社会论,由城市生态系统、共生城市、精明增长和公交导向细化为低碳社区的构建;在方法上,由单一计算转变到综合评估,由衍生方法借用转到低碳城市模型方法的提出;数据使用由估测数据转向明确的环境账户;空间尺度由城市个体向家庭、社区、园区、城市群等不同层面扩展;研究地域则从少数发达国家推广到发展中国家。基于低碳城市研究体系的不完备性和多学科交叉性、数据的不确定性、时空尺度的多样性等特点,当前研究应从城市共生和谐论出发,以微观尺度的调查数据为基础,综合利用现代空间信息技术,建立城市碳排放账户,对城市碳能源—经济—社会—环境(CEESE)系统的功能与机理、过程与控制以及关联与效应进行探索,创建低碳城市研究的理论与方法体系。
中国低碳发展的类型及空间分异
张金萍,,孙玮,耀辰
资源科学 , 2014,
Abstract: 区域的低碳发展是科学界关注的热点.本文以中国301个地级行政区为基本单元建立量化指标体系,把2011年中国低碳发展水平分为4个一级类型和8个二级类型,并通过Moran指数与散点图、LISA集聚图,结合基于扩展断裂点模型的中国经济区划分方案,分析低碳发展类型的宏观和局域分异特征,对于制定有针对性的不同类型区低碳发展政策具有重要意义.研究表明,中国低碳发展以高碳和相对高碳类型为主,一级经济区内低碳发展类型多样化分布,而大多数二级经济区内低碳发展类型具有相近性.依赖于高耗能产业结构的LLL和LHL类型在胡焕庸线上方和沿线集聚分布,而低碳经济与社会发展动力不足的LLH类型主要分布在胡焕庸线下方.低碳和相对低碳类型位于胡焕庸线下方,特别是在东部沿海和长江中游地区大量分布.在局域空间,各子系统发展存在着很强的正向空间依赖,低碳经济与社会发展以"LL"型集聚为主,但后者的空间异质性较强,而低碳环境发展则以"HH"型集聚为主.各子系统发展的热点区大多位于中国东部和南部且较为独立,冷点区则有所重叠,主要位于内蒙古西部及西北经济区连片地区.
航空发动机转子碰摩故障瞬时频率诊断方法
张志禹,吕延军,张九龙,
交通运输工程学报 , 2007,
Abstract: 分析了航空发动机转子碰摩故障振动信号的基本特征,提出了故障信号瞬时频率诊断方法。运用解析小波将故障信号变换到小波域,利用小波系数的振幅和相位信息综合确定瞬时频率,根据瞬时频率的特征诊断故障,并对比了故障信号瞬时频率诊断方法与窗口Fourier变换方法故障诊断结果。数值分析结果表明利用瞬时频率诊断方法提取碰摩信号的瞬时频率比利用窗口Fourier变换得到的结果更精细,并可获得用短时Fourier变换无法得到的一些瞬时频率曲线。
考虑分离和重新接触的涡轮自带冠叶片振动特性分析
Vibration Characteristics Analysis of Integrally Shrouded Turbine Blade Considering Separation and Reattachment

何冰冰,任兴民,何尚文,,马引钢
- , 2018,
Abstract: 研究了涡轮自带冠叶片在考虑叶冠间不同接触情况下的非线性振动响应。建立了考虑相邻叶冠间的分离和重新接触以及离心刚化效应的涡轮自带冠叶片的弹簧质量模型,并推导了其动力学方程。碰撞力采用更符合实际的线性弹簧和非线性弹簧的组合来进行建模,摩擦力则采用依赖速度的指数型摩擦模型。仿真结果表明,涡轮自带冠叶片可以表现出非常复杂的非线性现象,并且可以出现周期1、周期2、周期3、周期4和混沌运动。间隙不对称会使自带冠叶片的运动更加复杂。
The nonlinear forced vibration responses of integrally shrouded turbine blade considering different contact state are investigated in this paper. A lumped mass model of integrally shrouded turbine blade considering separation and reattachment of adjacent shrouds and centrifugal stiffening effects is established and its dynamic equation is deduced. Collision force is approximated by linear and cubic springs together which is more realistic, and friction force is approximated by an exponential-type velocity-dependent model. Numerical results indicate that integrally shrouded turbine blade displays very complex nonlinear phenomena and it can experience periodic 1, periodic 2, periodic 3, periodic 4 and chaotic vibration. Gap asymmetry leads to more complicated motions of the shrouded blade
非线性双稳态压电俘能系统阱间阱内运动谐波分析
Harmonic Analysis of a Bistable Piezoelectric Energy Harvester on Intrawell and Interwell Oscillations

朱培,任兴民,,周志勇
- , 2018,
Abstract: 首先对压电俘能系统进行了平衡点分岔分析,证明其具有非线性双稳态特性,并且得到系统的运动方程。再采用谐波平衡法对双稳态压电俘能系统进行分析,推导出了激励幅值、激励频率、响应幅值及输出功率之间的解析关系式,预测了结构的阱内、阱间动力学响应。分析了阻尼、阻抗、激励幅值、激励频率等参数对响应幅值及输出功率的影响。结果表明,阻尼、阻抗对能量获取频带宽度、响应幅值有较大影响。系统阱间、阱内运动均有高、低能量态共存现象,不同激励幅值和激励频率下存在最优阻抗使得输出功率最大。
Firstly, the equilibrium bifurcation analysis of the piezoelectric system proves its nonlinear bistable characteristics, and also obtains the equations of motion. Then, the harmonic balance method is applied to derive relationship of the excitation amplitude, excitation frequency, response amplitude and output power. It could predict dynamic responses of the intrawell and interwell oscillations of the bistable piezoelectric energy harvester. The effects of the parameters, such as damping, impedance, excitation amplitude and excitation frequency on the response amplitude and output power, are analyzed. The results show that the damping and impedance have a great influence on the width and the amplitude of the energy harvester. There exist the high and low energy states for intrawell and interwell oscillations. The maximum power could be got by adjusting impedance under the excitation with different amplitudes and frequencies
Detecting faint variation in signal by synchronization of Duffing system
利用Duffing系统的同步识别信号中的微小差别

Qin Wei-Yang,Su Hao,Yang Yong-Feng,
,苏 浩,杨永峰

物理学报 , 2008,
Abstract: For nonlinear Duffing system, a derived synchronization system is built and the method is proved. By the synchronization, the faint difference in stimulating signal of Duffing system can be detected. In simulation, when there occurs chaos in the original system, the responses of the original and derived system will exhibit synchronization for identical input signal and non-synchronization for different input signal. When the system is in quasi-periodic motion, the synchronization is still sensitive to the faint variation in the input signal. The simulation results prove the effectiveness of the method.
我国城市居民直接能耗的碳排放类型及影响因素
张艳,耀辰,,张金萍,张丽君,鲁丰先,王喜
地理研究 , 2012, DOI: 10.11821/yj2012020014
Abstract: 针对我国287个地级以上城市,在测算了近9年居民直接能耗导致的CO2排放量的基础上,进行聚类、对比,并分析城市居民直接能耗的碳排放影响因素,得到以下结论全国分为6类城市居民直接能耗碳排放类型;高碳排放型城市的地均碳排放强度、人均工资碳排放强度及居民直接能耗CO2排放总量等方面均比低碳排放型城市高,人均地方生产总值碳排放强度低于低碳排放型城市,并多为经济发达城市和资源丰富城市,其碳排放构成上分别以电、交通能耗碳排放和气碳排放为主导,高碳排放型城市居民直接能耗CO2排放量占全国地级以上城市的86.20%。我国大部分地级城市居民直接能耗的碳排放属于相对低碳排放型,其人均CO2排放量低于全国平均水平。城市所在地的降温度日数(CDD)、采暖期、采暖强度、人均能源供给量、居民的人均工资、城市人均地方生产总值是影响城市居民直接能耗CO2排放量的主要因素。
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