共查询到20条相似文献,搜索用时 46 毫秒
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针对热泵型纯电动客车空调系统在冬季低温高湿环境下,车外换热器易结霜而造成系统制热性能严重衰减的问题,开发了一种带有经济器的补气型纯电动客车热泵空调系统,对车外管翅式换热器结霜特性进行了实验研究。结果表明,当车外换热器完全结霜后,系统制热量和COP均大幅下降。由于采用中压补气技术,系统仍能稳定运行,当车外温度为0、-10、-20℃时,结霜过程中系统制热量分别降低了5、3.2、2.3 kW,COP分别降低了1.1、0.7、0.45,且车外空气相对湿度越大,系统制热性能衰减越严重。 相似文献
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针对电动客车用热泵空调器在低温工况下压缩比大、排气温度高、容积效率偏低、系统性能降低等突出问题,提出了带经济器的补气技术,并对系统循环过程进行理论分析,测试了在-15℃的环境温度、不同压缩机转速下,补气技术对电动客车用低温变频空调器的性能影响。结果表明:与不补气的热泵空调器相比,采用补气技术可显著降低压缩机排气温度,使系统安全可靠运行,特别是压缩机转速为5000r/min时,不补气时排气温度高达116.7℃,而补气时排气温度为99.6℃,相比下降了14.7%;采用补气技术提升了系统制热量和制热性能系数COP,且随着压缩机转速的提高,其效果更加显著,当压缩机转速由2000r/min提高到5000r/min时,与不补气的热泵空调器相比,系统制热量提升了16.2%~22.7%,COP提升了2.8%~14.2%。 相似文献
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We investigate self-diffusion in a classical fluid composed of two species which are distinguished through the color of their particles, either black or white, but are identical as regards their mechanical properties. Disregarding color the fluid is in thermal equilibrium. We show that if a single test particle in the one-component fluid moves asymptotically as Brownian motion, then the color density and current in certain classes of nonequilibrium states are related, on the appropriate macroscopic scale, through Fick's law, and the former is governed by the diffusion equation. If in addition several test particles move asymptotically as independent Brownian motions, then the colored fluid is, on a macroscopic scale, in local equilibrium with parameters governed by the solution of the diffusion equation.Part of this work was done while both authors were at IHES, Bures-sur-Yvette, France.Supported in part by NSF Grant No. PHY 78-15920-02.Supported by a Heisenberg fellowship of the Deutsche Forschungsgemeinschaft. 相似文献
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We present identities relating the equations of motion of various quasiprobabilities for quantum oscillators. These identities turn out useful for checking the consistency of approximations made in constructing the equations of motion with the basic Bose commutator. Moreover, our identities allow to identify the quasiprobability distributions which have the easiest-to-solve equations of motion. 相似文献
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Jaeyeol Ryu N. V. Muravyev A. N. Putilin 《Bulletin of the Lebedev Physics Institute》2018,45(1):14-18
Currently, there are many types of virtual displays and new types arise every year. However, their vast majority appear technically inapplicable because they are inconsistent with a number of key factors related to the eye physiology. In this paper, we present the general requirements for optical systems of virtual displays, taking into account human eye physiology. 相似文献
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How should one select the best detector for a particular measurement in energy dispersive X‐ray fluorescence (EDXRF)? How should one select the optimum system configuration, i.e. the best shaping time and beam current? Manufacturers provide a variety of specifications, such as energy resolution and maximum count rate, but these are indirectly related to the end use of an EDXRF instrument, the measurement and detection limit of the measured elemental concentrations. We suggest in this paper using the time required to achieve a given statistical uncertainty as a figure of merit. We derive scaling rules for this figure of merit based on conventional specifications, including energy resolution, peaking time, maximum count rate, detector area, and intrinsic efficiency. These scaling rules also include the peak to background ratio of a photopeak and the number of overlapping peaks. We then show how this figure of merit can be used to select the optimum detector and spectrometer configuration for specific applications and compare the results to data obtained with typical systems. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Memory for pitch versus memory for loudness 总被引:5,自引:0,他引:5
The decays of pitch traces and loudness traces in short-term auditory memory were compared in forced-choice discrimination experiments. The two stimuli presented on each trial were separated by a variable delay (D); they consisted of pure tones, series of resolved harmonics, or series of unresolved harmonics mixed with lowpass noise. A roving procedure was employed in order to minimize the influence of context coding. During an initial phase of each experiment, frequency and intensity discrimination thresholds [P(C) = 0.80] were measured with an adaptive staircase method while D was fixed at 0.5 s. The corresponding physical differences (in cents or dB) were then constantly presented at four values of D: 0.5, 2, 5, and 10 s. In the case of intensity discrimination, performance (d') markedly decreased when D increased from 0.5 to 2 s, but was not further reduced when D was longer. In the case of frequency discrimination, the decline of performance as a function of D was significantly less abrupt. This divergence suggests that pitch and loudness are processed in separate modules of auditory memory. 相似文献
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溶剂化的热力学集团展开理论 总被引:1,自引:0,他引:1
把二元溶液的过剩内能(excess energy)分成溶剂-溶剂、溶剂-溶质及溶质-溶质相互作用部分。利用集团展开方法给出了二元溶液在正则系综的配分函数的表达式,利用该表达式得到了溶质的偏摩尔内能(partial molar energy)和偏摩尔熵(partial molar entropy)的表达式。在无限稀溶液情形,过剩偏摩尔内能的溶剂-溶剂部分又称重组织内能(reorganization energy),它反映了溶质存在时对其周围溶剂分子之间的相互作用能的影响。研究表明,在溶质的粒子数密度相对较大时,溶质分子之间的相互作用将影响过过剩偏摩尔内能的溶剂-溶剂部分,对于稀溶液,过氧偏摩尔内能的溶剂-溶剂部分与溶质的摩尔分数成线性关系。对低蜜度二元溶液,溶质的过剩偏摩尔内能和过剩偏摩尔熵也与溶质的摩尔分数成线 相似文献
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Expressions for third-order aberration in the reconstructed wave front of point objects are established by Meier. But Smith,
Neil Mohon, Sweatt independently reported that their results differ from that of Meier. We found that coefficients for spherical
aberration, astigmatism, tally with Meier’s while coefficients for distortion and coma differ. 相似文献
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Olga Nánásiová 《International Journal of Theoretical Physics》2003,42(9):1889-1903
In this paper we will study a function of simultaneous measurements for quantum events (s-map) which will be compared with the conditional states on an orthomodular lattice as a basic structure for quantum logic. We will show the connection between s-map and a conditional state. On the basis of the Rényi approach to the conditioning, conditional states, and the independence of events with respect to a state are discussed. Observe that their relation of independence of events is not more symmetric contrary to the standard probabilistic case. Some illustrative examples are included. 相似文献