共查询到20条相似文献,搜索用时 0 毫秒
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Hector Campello-Vicente Ramon Peral-OrtsNuria Campillo-Davo Emilio Velasco-Sanchez 《Applied Acoustics》2017
The electric vehicle is the best-positioned alternative to the ICE conventional vehicle become of, among other reasons, its environment friendly properties. One of its most significant properties is its quiet electric engine which can be a good tool for decreasing noise pollution in cities. 相似文献
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We consider the model problem of atmospheric electricity generation by the combined action of the planetary generator due
to nonsolid rotation of the plasmasphere and the current due to low-latitude thunderstorms. The exact solution for this model
explains satisfactorily many experimental findings connected with the total electric charge of the planet, the vertical current
density, and electric fields in a good weather zone.
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii,
Radiofizika, Vol. 40, Nos. 1–2, pp. 138–145, January–February, 1997. 相似文献
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T. Pesch H.-J. Allelein J.-F. Hake 《The European physical journal. Special topics》2014,223(12):2561-2575
The German Energiewende, the transformation of the energy system, has deep impacts on all parts of the system. This paper presents an approach that has been developed to simultaneously analyse impacts on the energy system as a whole and on the electricity system in particular. In the analysis, special emphasis is placed on the transmission grid and the efficiency of recommended grid extensions according to the German Network Development Plan. The analysis reveals that the measures in the concept are basically suitable for integrating the assumed high share of renewables in the future electricity system. Whereas a high feed-in from PV will not cause problems in the transmission grid in 2022, congestion may occur in situations with a high proportion of wind feed-in. Moreover, future bottlenecks in the grid are located in the same regions as today. 相似文献
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针对高超声速飞行器防热, 搭建了螺线管磁控热防护系统的物理模型. 采用低磁雷诺数磁流体数学模型, 分析了外加磁场强度及磁场形态对磁控热防护效果的影响. 对比了三种磁场类型(磁偶极子、螺线管、均布磁场)下磁控热防护效果的差异, 分析了螺线管几何参数对磁控热防护效果的影响. 研究表明, 磁场降低表面热流作用存在“饱和现象”; 三种磁场形态的磁控热防护能力从小到大依次为磁偶极子、螺线管、均布磁场; 相同驻点磁感应强度条件下, 增大螺线管半径有利于提高磁控热防护效果, 缩短螺线管与驻点距离不利于驻点和肩部防热, 螺线管长度对磁控热防护效果影响相对较小. 相似文献
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针对道路拥堵车辆调度问题,设计了一种基于物联网视觉的大型拥堵车辆调度系统,分析了系统的总体结构,给出了系统的ZigBee协调器模块、车载传感器节点、图像采集处理模块以及无线传输模块的硬件结构,详细介绍了拥堵车辆调度算法流程,并给出了车辆调度最佳路径算法代码,实现了大型拥堵车辆的有效调度。实验结果说明,所设计系统可获取有效的交通车辆拥堵图像,实现交通拥堵的高效调度。 相似文献
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A. Härter A. Krükow A. Brunner J. Hecker Denschlag 《Applied physics. B, Lasers and optics》2014,114(1-2):275-281
We investigate the evolution of quasi-static stray electric fields in a linear Paul trap over a period of several months. Depending on how these electric fields are initially induced, we observe very different timescales for the field drifts. Photo-induced electric fields decay on timescales of days. We interpret this as photo-electrically generated charges on insulating materials which decay via discharge currents. In contrast, stray fields due to the exposure of the ion trap to a beam of Ba atoms mainly exhibit slow dynamics on the order of months. We explain this observation as a consequence of a coating of the trap electrodes by the atomic beam. This may lead to contact potentials which can slowly drift over time due to atomic diffusion and chemical processes on the surface. In order not to perturb the field evolutions, we suppress the generation of additional charges and atomic coatings in the Paul trap during the measurements. For this, we shield the ion trap from ambient light and only allow the use of near-infrared lasers. Furthermore, we minimize the flux of atoms into the ion trap chamber. Long-term operation of our shielded trap led us to a regime of very low residual electric field drifts of less than 0.03 V/m per day. 相似文献
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P Hoole 《The Journal of the Acoustical Society of America》1999,106(2):1020-1032
A hybrid PARAFAC and principal-component model of tongue configuration in vowel production is presented, using a corpus of German vowels in multiple consonant contexts (fleshpoint data for seven speakers at two speech rates from electromagnetic articulography). The PARAFAC approach is attractive for explicitly separating speaker-independent and speaker-dependent effects within a parsimonious linear model. However, it proved impossible to derive a PARAFAC solution of the complete dataset (estimated to require three factors) due to complexities introduced by the consonant contexts. Accordingly, the final model was derived in two stages. First, a two-factor PARAFAC model was extracted. This succeeded; the result was treated as the basic vowel model. Second, the PARAFAC model error was subjected to a separate principal-component analysis for each subject. This revealed a further articulatory component mainly involving tongue-blade activity associated with the flanking consonants. However, the subject-specific details of the mapping from raw fleshpoint coordinates to this component were too complex to be consistent with the PARAFAC framework. The final model explained over 90% of the variance and gave a succinct and physiologically plausible articulatory representation of the German vowel space. 相似文献
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采用铝合金高压线束替代铜合金高压线束可帮助电动汽车减少重量、提高续航和降低成本。针对铝与铜由于金属性质差异难以可靠连接的问题,本文提出采用电磁脉冲压接技术连接铝合金高压线束与铜合金接线端子,并研制了一套适用于两者连接的电磁脉冲压接装置,其最大放电能量为28 kJ。压接过程中,随着放电电压的升高,接线端子表面的温度升高。当放电电压为12 kV时,实现了铝合金高压线束与铜合金接线端子的可靠连接。采用光学显微镜分析连接界面的微观结构,并测试其电气性能和机械性能。分析结果表明:电磁脉冲压接技术可实现铝合金高压线束与接线端子、铝合金芯线之间的冶金结合,且连接界面出现了波纹形貌与涡旋形貌。测试结果显示:接头接触电阻测试、振动测试、拉力负荷测试均满足汽车行业标准和电缆接头国家标准。 相似文献
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针对校园中现有用电管理系统的存在的缺陷与弊端,提出了一种基于B/S架构的嵌入式远程用电管理系统的解决方案。系统以ARM-CORTEX-A8为主控板的核心处理器,Linux操作系统为应用程序的运行环境,同时在Linux系统中搭建了嵌入式BOA服务器。系统中使用html语言完成系统与用户的交互页面,并通过CGI技术实现了浏览器与嵌入式服务器的数据交互。为不改变原有建筑电力布线,系统终端采用zigbee无线网络实现远程的用电监控,从而实现远程用电管理系统。为使系统运行效率高,主进程中使用多线程技术完成系统中各任务,系统中使用数据共享内存的方式完成各进程间的数据通信,使用消息队列实现客户端对系统终端设备的控制,系统中通过sqlite3数据库完成所有历史数据的记载。通过系统实验测试,该系统可以正确响应用户需求以及满足校园内所设置的合理用电申请的远程用电管理要求,在安全、节约用电的同时有最大程度的方便了校园内非常规工作需求。 相似文献
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This paper considers a small oscillatory motion of a pendulum suspended on a single-degree-of-freedom system subjected to a narrow band excitation and impacts due to a barrier located at a certain distance from the system?s equilibrium position. The influence of a impacting motion of the single-degree-of-freedom system onto the instability boundaries of the pendulum is investigated. It is demonstrated that the impacting motion significantly changes the shape of the instability domain compared to the traditional one inherent to the Mathieu equation. 相似文献
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为了提高电池管理系统中多块单体电池电压的采集速度与效率,提出了一种基于FPGA控制ltc6804-2的电池管理系统。单个Ltc6804-2里的ADC采集功能仅在20us内就可完成对12块单体电池的电压或电流的采集,并且多块ltc6804-2可进行级联从而可监测系统设备所需的单体电池电压,FPGA通过SPI总线与ltc6804-2实现通信,可快速获取多块单体电池的电压或电流从而可以在其内部实现系统的充放电均衡、荷电状态(SOC)估计等功能,并且精确度高,使整套设备更加简化与可靠,效率更高。本系统可广泛应用于电动汽车或通用航空机上。 相似文献
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We investigate the influence of an external electric field on the dewetting behavior of nitrogen-water systems between two hydrophobic plates using molecular dynamics simulations. It is found that the critical distance of dewetting increases obviously with the electric field strength, indicating that the effective range of hydrophobic attraction is extended. The mechanism behind this interesting phenomenon is related to the rearrangement of hydrogen bond networks between water molecules induced by the external electric field. Changes in the hydrogen bond networks and in the dipole orientation of the water molecules result in the redistribution of the neutral nitrogen molecules, especially in the region close to the hydrophobic plates. Our findings may be helpful for understanding the effects of the electric field on the long-range hydrophobic interactions. 相似文献
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Study of relativistic effects in the interaction of a spin-1/2 electric charge in the radial field of a spin less point like
dyon has been undertaken using Dirac’s relativistic equation. Angular momentum and energy eigen values have been obtained.
The deviations of the results from those of hydrogen atom like systems have been discussed. 相似文献
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R. Böhm W. Engel S. Hoth W. Klinger R. Seeböck W. Withuhn 《Zeitschrift für Physik B Condensed Matter》1980,39(2):115-124
Magnetic and electric hyperfine interactions in the system EuSm were investigated with the isomeric 11/2– state in145Eu by applying the time-differential perturbed angular distribution (TDPAD) method. The temperature dependence of paramagnetism was studied between 90 K and 1000 K by measuring the magnetic hyperfine interaction frequency L=gNN1 (T)Bext. The paramagnetic correction factor strictly follows the Curie-Weiss relation =1+C/(T-), withC=–50(2) K and =–29(5) K. This is compatible with a hyperfine field ofB
int(0)=–25(1) T, a valence of two for Eu in Sm, and antiferromagnetic order at low temperatures.The temperature dependence of the electric quandrupole coupling constant vQ, investigated between 100 K and 400 K, can be reproduced by a linear temperature variation vQ(T)=vQ(0) (1-AT), with vQ(0)=16.2(4) MHz andA=7.2(8)·10–4 K–1.The paramagnetic relaxation time rel of the nuclear alignment is proportional to the temperature of the sample, with rel T–1=3.7(2) ·10–9s K–1.This leads to the Korringa relation J T=const=5.1(5)·10–11s K for the relaxation time of the 4f electronic spinJ. Assuming that the relaxation ofJ is mainly caused by exchange interaction between conduction electrons and localized 4f electrons at the Eu site, an exchange integral of |J
eff|=0.10(2) eV can be deduced. 相似文献