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Search Results: 1 - 10 of 250381 matches for " 张 玥 "
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古罗马帝国兴衰原因探讨
An Analysis of the Rise and Fall of the Roman Empire
 [PDF]

, 蔡恒进
Emergence and Transfer of Wealth (ETW) , 2012, DOI: 10.12677/ETW.2012.23013
Abstract:
一个国家的兴衰很大程度上依赖于该国的财富涌现能否满足人民的自我肯定需求。从公元前8世纪建城到公元2世纪,古罗马用了1000多年的时间崛起从而称霸欧、亚、非大陆,却在不到200年的时间里迅速瓦解衰败。本文通过分析古罗马人口和疆域变化,从财富涌现和流转的角度探索其兴衰的原因。古罗马的兴盛缘于侵略扩张与自主创新如土地分配和道路发展的共同作用,在600余年间实现人口增加600余倍和国土增加6000余倍的剧变。而当扩张逐渐停止、道路系统达到饱和后,透支未来和宗教便登上历史的舞台,成为维持帝国的主流方式。但无论财富如何增长都会有极限,当财富供需失去平衡、宗教的力量无法凝聚民众时,各种社会矛盾便相继爆发,罗马便日渐式微,最终走向灭亡。
The vicissitudes of a nation largely depends on whether its wealth emergence can meet people’s self-assertiveness demands. From the eighth century B. C. to the second century A. D., Roman had grown into the most powerful country dominating Europe, Asia and Africa within more than 1000 years. However, she just collapsed within less than 200 years. Based on the analysis of demographic and territorial changes of Roman, it is found that the rise of Roman results from a synergic effect of both expansions and innovations as indicated by road system constructions and land distributions. In about 600 years, the population and territory had increased by 600 times and 6000 times respectively. As expansions and road system constructions reached their limits, overdraw from the future and religion practice became the dominant governing method to maintain the empire. However, when the wealth emergence mentioned above exhausted and all governing institutions stopped functioning, Roman Empirecame to an end.
抽样定理的若干基本问题的讨论
Discussion of Some Basic Problems on Sampling Theorem
 [PDF]

樊同亮,, 玉元
Hans Journal of Wireless Communications (HJWC) , 2015, DOI: 10.12677/HJWC.2015.54012
Abstract: 抽样定理是《通信原理》课程中的重点和难点,抽样定理在连续时间信号与离散时间信号之间架起了一座桥梁。本文首先给出抽样定理及信号恢复理论的证明,得到了信号重建的条件,并对抽样定理的适应性进行详尽的阐述讨论。利用实验箱建立信号的采样与重建的实验系统,通过设置不同的采样频率,得到在不同频率的情况下信号的恢复波形,从而直观地验证了抽样定理。
Sampling theorem is the important and difficult knowledge point in the course of communication principle. Sampling theorem sets up a bridge between continuous-time signal and discrete-time signal. Sampling theory and theory of signal reconstruction are proved theoretically. The adapta-bility of sampling theory is thoroughly discussed. The experiment system on sampling and recon-struction on signal using experimental box is established. By setting different sampling frequency, the recovery of signal is obtained at different frequency. The sampling theorem is intuitively veri-fied.
CPFR下基于存销比的烟草库存管理
Cigarette Inventory Management Based on Stock-to-Sales Ratio in CPFR Framework
 [PDF]

艳霞, , 徐跃明, 葛文, 张恩华, 周海滨
Management Science and Engineering (MSE) , 2013, DOI: 10.12677/MSE.2013.23012
Abstract:

在烟草行业中卷烟生产带有明显的计划色彩,而销售却表现出很强的市场特征。库存在计划供应与市场需求的匹配中起着重要作用。存销比是烟草行业库存控制的通用指标。本文探讨了VMI模式在实践应用的局限性。构建了烟草行业的两阶段供应链CPFR(联合计划、预测和补货Collaborative planning, forecasting and replenishment, CPFR)体系框架。研究了在CPFR体系下存销比库存控制参数的设定。
In tobacco industry, the production of cigarette is controlled by national plan. But the sale of ciga- rette is market facing. Stock plays an important role in the matching of planned production and customer de- mand. Stock-to sales ratio is the common index that is used in inventory management in tobacco industry. The paper discussed the limitation of VMI in practice. A CPFR (Collaborative planning, forecasting and re- plenishment) framework of a two-stage supply chain for tobacco industry was proposed. The inventory man- agement parameter based on stock-to sales ratio was researched.

大中华地区主管领导风格与员工工作后果之关联:以自我观为调节变项
The Moderating Effects of Self-Views in the Relationships between Leadership Styles and Subordinates’ Work Consequences
 [PDF]

, 陆洛, 陆昌勤, 周君倚
Vocational Education (VE) , 2013, DOI: 10.12677/VE.2013.21001
Abstract:

本研究目的为探讨主管“转换型领导”与“交易型领导”风格与员工工作后果(包括:工作满意度、组织公民行为、组织承诺、工作绩效)之间的关联,并探讨员工自我观的调节作用。有效样本为784名全职员工,其中台湾样本446名,大陆样本338名。资料分析采用阶层回归来验证假设,结果显示:1) 转换型领导是四个后果变项的预测因子,交易型领导则是工作满意度与组织承诺的预测因子。2) 自我观会调节转换型领导与工作后果的关联。当员工具有高度“社会取向”自我观,会“强化”转换型领导对工作绩效的正向效果,会“弱化”交易型领导对工作满意度的正向效果。而当员工具有高度“个人取向”自我观,则会“弱化”交易型领导对组织公民行为的正向效果。显示员工之自我观为领导效能的重要权变因子。

The aim of this research was to explore the relations among supervisors’ transformational leadership, transactional leadership, and subordinates’ work outcomes (including job satisfaction, organizational commitment, organizational citizenship behavior, and job performance). Using structured questionnaires, a diverse sample of 784 full-time employees drawn from a variety of organizations in Taiwanand mainlandChinawas surveyed. Analyses revealed that transformational leadership was positively related to all four outcome variables in our study; whereas transactional leadership was positively related to job satisfaction and organizational commitment. More importantly, we found that the social-oriented self view enhanced the positive effect of transformational leadership on job performance but mitigated the positive effect of transformational leadership on job satisfaction. On the other hand, the individual-oriented self view mitigated the positive effect of transactional leadership on organizational citizen behavior. It is thus recommended that employee’s self views may be important contingent factors of leadership effectiveness.


 

湘鄂西地区五峰–龙马溪组富有机质页岩段沉积–地化特征
Sedimentation and Geochemistery Features of the Organic-Riched Shale in Wufeng-Longmaxi Formation, West of HuNan-HuBei Province
 [PDF]

代美林, 胡青, 小青,, 胡忠贵
Advances in Geosciences (AG) , 2012, DOI: 10.12677/AG.2012.24031
Abstract: 湘鄂西地区五峰龙马溪组为一套厚层的泥页岩层根据其沉积特征确定该区沉积相类型为碎屑岩陆棚相进一步细分为浅水陆棚和深水陆棚亚相。结合沉积和地球化学特征分析表明:五峰组龙马溪组下段以灰黑色、深灰色硅质页岩、炭质页岩和笔石页岩为主具有连续性沉积平均厚度达50 m左右区域分布稳定埋藏深度较浅TOC平均值达1.33%热演化程度较高有机质类型以大多以型为主是页岩气发育的有利层段。经河页1井钻井证实该区五峰龙马溪组具有一定的含气性。因而开展页岩气沉积、地化特征等基础研究对于该区页岩气勘探工作具有重要地质意义。
Hunan-Hubei region Wufeng-Longmaxi Formation is a
中长期水文预报的最优组合模型研究
Mid and Long-Term Hydrological Forecasting Using Optimal Combined Model
 [PDF]

, 刘攀, 黄焕坤, 李立平, 虞云飞, 安标
Journal of Water Resources Research (JWRR) , 2013, DOI: 10.12677/JWRR.2013.26053
Abstract: 本文建立了径流中长期预报的自回归、季节性自回归、门限自回归、最近邻抽样回归、人工神经网络、支持向量机等六种模型,并对这些模型结果进行综合,开展最优组合预报。以飞来峡水库为研究实例,选取平均绝对误差和均方误差作为评价指标,发现人工神经网络模型模拟精度较高;支持向量机模型模拟精度高、且具有最好的预报性能;最优组合预报模型综合各单一预报模型的优点,结果稳健、通用性强。
This paper applies six models, including the autoregressive model, the seasonal autoregressive model, the threshold autoregressive model, the nearest neighbor bootstrap regressive model, the artificial neural network model and the support vector machine model into the mid and long-term hydrological forecasting. Based on Feilaixia reservoir project, the results show that the artificial neural network model is able to time series very well. The support vector machine model has the powerful ability of not only the simulation but also the forecasting. The results of those models were combined by the optimal combined forecasting model. The mean absolute error and the mean square error are selected as the measurements. Relying on the merits of each single model, the results of the optimal combined forecasting model work very well and are very well in robustness.
笼型转子异步磁力耦合器的温度场研究
Research on the Temperature Field of Asynchronous Magnetic Coupling
 [PDF]

葛研军, 姜玉龙, 肖奇, ,
Mechanical Engineering and Technology (MET) , 2015, DOI: 10.12677/MET.2015.41001
Abstract:
为获得笼型转子异步磁力耦合器(Asynchronous Magnetic Coupling, AMC)工作时的内部温升,基于AMC运行机理建立数理模型,通过变分原理计算出AMC温度场的理论值,并利用Ansoft及ANSYS Workbench联合仿真计算出AMC温度场的有限元值,并最终通过实验测出AMC的实际温度。结果表明:AMC理论计算及有限元分析结果与实测值相当,证明了所建AMC理论模型的正确性。
In order to obtain the internal temperature rise of Asynchronous Magnetic Coupling (AMC) in working, the mathematical model is established based on the operational mechanism of AMC. The theoretical value of the temperature field of AMC is calculated by the variational principle and the finite element value of the temperature field is calculated by simulation of Ansoft and ANSYS Workbench. Finally, the actual temperature is measured by the experiment. The results show that the theoretical calculation and the finite element analysis result are as equivalent as those of measured value, proving the validity of the established AMC theoretical model.
欧亚大陆积雪分布及其类型划分
廷军,钟歆
冰川冻土 , 2014, DOI: 10.7522/j.issn.1000-0240.2014.0058
Abstract: 利用1966-2012年欧亚大陆1152个地面气象台站积雪深度资料,对欧亚大陆积雪深度、累计积雪天数和连续积雪天数的空间分布进行了分析,以连续积雪天数为标准对欧亚大陆季节性积雪类型进行了划分,并与应用累计积雪天数对积雪区类型的划分进行了比较研究.结果表明欧亚大陆积雪分布具有显著纬度地带性特征,积雪深度、累计积雪天数和连续积雪天数的大值分布区均位于俄罗斯平原的东北部、科拉半岛、西西伯利亚平原、中西伯利亚高原以及俄罗斯远东北部大部分区域.与累计积雪天数划分方法相比,利用连续积雪天数对欧亚大陆季节性积雪分区,在前苏联地区积雪类型分区差异并不显著,但蒙古和中国的稳定积雪区明显缩减,青藏高原无稳定积雪区,中国大部分地区为非周期性不稳定积雪区.两种积雪分区划分方法比较结果显示,连续积雪天数划分方法更能体现积雪累积的连续性和持久性,更符合对稳定积雪和不稳定积雪的划分标准.
卷积完全匹配层截断3维金属矩形波导的应用研究
,王建国,殿辉
强激光与粒子束 , 2005,
Abstract: ?讨论了高功率微波源模拟中波导开放边界截断的需求,分析了不同类型完全匹配层(pml)的特点,选用卷积形式pml截断色散波导器件的开放边界。从自由空间电磁波的平面波解和分裂形式的pml出发,构造了未分裂形式的pml,用傅里叶变换的卷积定理,导出了直角坐标系下卷积完全匹配层(cpml)介质中电磁场的迭代形式的离散方程。在不同频率和模式激励源作用下,模拟计算了cpml截断矩形波导开放边界的性能,数值结果表明最大相对误差都小于-70db,远好于mur吸收边界的截断效果。
淡水浮游硅藻对氮磷的最适需求量
苏建国?, ,许 英?
西北农林科技大学学报(自然科学版) , 2002,
Abstract: 报道了淡水浮游硅藻所需的最适氮磷值,试验分2个阶段。第1阶段将氮定为0.50μg/g,把氮磷比设为6/1,7/1和8/1,溶于自来水进行5d培养后用碘液固定,然后稀释10倍用浮游植物计数框记数50个视野,根据结果进一步试验得出最适的氮磷比为7.3/1。第2阶段在第1阶段的基础上,首先将氮的浓度设为0.34,1.17及2.00μg/g,培养后固定、稀释、计数,根据结果进一步预试验得出氮的最适需求量在1.59~1.80μg/g;氮为1.59,1.70及1.80μg/g时,淡水浮游硅藻的数量分别为(280±9.3),(304.7±4.8)及(290.0±5.6)个,对照组为(188.5±9.5)个。结果表明:氮为1.70μg/g,磷为0.233μg/g是淡水浮游硅藻的最适需求量。
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