自由空间量子通讯实验中纠缠源的研制

设计了适合自由空间量子通讯实验的纠缠源. 纠缠光子对的单模光纤搜集率约为每秒20000对,水平竖直方向的纠缠对比度大于95%,正负45°方向的纠缠对比度大于90%. 在本地得到了大于100个标准偏差的Bell 不等式破缺. 满足20 km量级的自由空间量子通讯试验要求. 关键词： 纠缠光子对 位相匹配 收集效率 贝尔不等式     

基于编码器的复摆设计与实验研究

针对复摆实验,设计了一种基于编码器的复摆实验装置。该装置将摆锤和多孔摆结合起来,可以采用多种方式对重力加速度、转动惯量进行求解,并验证了刚体的平行轴定理。在实验过程中,采用Matlab进行最小二乘法线性拟合,创新性地完成了对重力加速度的求解和平行轴定理的验证。实验结果表明,相比于传统的复摆,该装置更为简便,精度更高。     

基于信息化技术的大学物理实验教学改革与探索

实验课程是提高大学生应用能力的一种重要手段。但近年来,一些高校的学生实验课成绩却出现了整体下滑的现象。为了进一步促进大学实验教学的改革与提升,本文对内蒙古工业大学五十余个专业近五年的物理实验课成绩进行了抽样分析。分析结果表明,实验教学内容更新缓慢,学生对物理实验的重视程度不够、实验本身吸引力欠缺、教法改进不足等都是导致学生成绩下滑的重要因素。针对这些问题给出了改进大学物理实验教学的方法和建议。     

The aspect experiment and the return to reality

It is argued that the results of atomic cascade photon correlation experiments of the static type may be given a natural interpretation in the framework of at least one objective local theory, namely stochastic electrodynamics. It follows that the Aspect experiment is more likely than the Clauser-Horne experiment to be crucial in deciding between objective local theories and quantum mechanics.     

The nEDM experiment at the SNS

The nEDM collaboration proposes to measure the neutron electric dipole moment at the Spallation Neutron Source (Oak Ridge National Laboratory). The nEDM is a clear signature of CP violation. According to the Standard Model the nEDM is very small (～10^?31 e cm), but many theories predict much higher values. In the proposed experiment polarized cold neutrons from the SNS would be trapped in liquid helium at a temperature of about 400 mK. The neutron spin would precess in a very uniform magnetic field (H ～ 30 mG), and the experiment would measure the change in the precession frequency when a very strong electric field (E ～ 50 kV/cm) is applied. Polarized ³He atoms serve as a co-magnetometer. The goal of the experiment is to measure the nEDM with an accuracy of ～9 × 10^?28 e cm, which is more than an order of magnitude better than existing results.     

The self-consistent cell model equation of state for solids

An anharmonic equation of state for solids using the Self-Consistent Cell Model (SCCM) is given in a form useful for calculating the usual thermodynamic properties. Following Cowley and Shukla, using the Jaswal-Girifalco potential for copper, calculations are compared with other models and with experiment. The results from the analytic expressions using the SCCM are as good or better than those obtained from far more complicated theories of anharmonicity. Using the Lindemann criterion, the pressure at the melting point was obtained as a function of the melting temperature. A melting line was also obtained for iron and the longitudinal velocity and isothermal bulk modulus along the melting line were calculated. The Hugoniot pressures were calculated and compared with experiment. For both the copper and iron the agreement between theory and experiment is remarkably good considering the empirical nature of the potentials, the simplifying approximations of the SCCM calculations, and the large range of densities and pressures that are compared with experiment.     

The interplay between the auditory and visual modality for end-of-utterance detection

The existence of auditory cues such as intonation, rhythm, and pausing that facilitate end-of-utterance detection is by now well established. It has been argued repeatedly that speakers may also employ visual cues to indicate that they are at the end of their utterance. This raises at least two questions, which are addressed in the current paper. First, which modalities do speakers use for signalling finality and nonfinality, and second, how sensitive are observers to these signals. Our goal is to investigate the relative contribution of three different conditions to end-of-utterance detection: the two unimodal ones, vision only and audio only, and their bimodal combination. Speaker utterances were collected via a novel semicontrolled production experiment, in which participants provided lists of words in an interview setting. The data thus collected were used in two perception experiments, which systematically compared responses to unimodal (audio only and vision only) and bimodal (audio-visual) stimuli. Experiment I is a reaction time experiment, which revealed that humans are significantly quicker in end-of-utterance detection when confronted with bimodal or audio-only stimuli, than for vision-only stimuli. No significant differences in reaction times were found between the bimodal and audio-only condition, and therefore a second experiment was conducted. Experiment II is a classification experiment, and showed that participants perform significantly better in the bimodal condition than in the two unimodal ones. Both the first and the second experiment revealed interesting differences between speakers in the various conditions, which indicates that some speakers are more expressive in the visual and others in the auditory modality.     

The effect of segmental and suprasegmental corrections on the intelligibility of deaf speech

Three experiments were conducted to study the effect of segmental and suprasegmental corrections on the intelligibility and judged quality of deaf speech. By means of digital signal processing techniques, including LPC analysis, transformations of separate speech sounds, temporal structure, and intonation were carried out on 30 Dutch sentences spoken by ten deaf children. The transformed sentences were tested for intelligibility and acceptability by presenting them to inexperienced listeners. In experiment 1, LPC based reflection coefficients describing segmental characteristics of deaf speakers were replaced by those of hearing speakers. A complete segmental correction caused a dramatic increase in intelligibility from 24% to 72%, which, for a major part, was due to correction of vowels. Experiment 2 revealed that correction of temporal structure and intonation caused only a small improvement from 24% to about 34%. Combination of segmental and suprasegmental corrections yielded almost perfectly understandable sentences, due to a more than additive effect of the two corrections. Quality judgments, collected in experiment 3, were in close agreement with the intelligibility measures. The results show that, in order for these speakers to become more intelligible, improving their articulation is more important than improving their production of temporal structure and intonation.     

The status of the study of solar CNO neutrinos in the Borexino experiment

Although less than 1% of solar energy is generated in the CNO cycle, it plays a critical role in astrophysics, since this cycle is the primary source of energy in certain more massive stars and at later stages of evolution of solar-type stars. Electron neutrinos are produced in the CNO cycle reactions. These neutrinos may be detected by terrestrial neutrino detectors. Various solar models with different abundances of elements heavier than helium predict different CNO neutrino fluxes. A direct measurement of the CNO neutrino flux could help distinguish between these models and solve several other astrophysical problems. No CNO neutrinos have been detected directly thus far, and the best upper limit on their flux was set in the Borexino experiment. The work on reducing the background in the region of energies of CNO neutrinos (up to 1.74 MeV) and developing novel data analysis methods is presently under way. These efforts may help detect the CNO neutrino flux in the Borexino experiment at the level predicted by solar models.     

The NMR multi-transmit phased array: a Cartesian feedback approach

The use of Cartesian feedback is proposed to solve the problem of using an array of coils for the purposes of transmission in magnetic resonance imaging. The difficulties caused by direct and sample-mediated coil interactions are briefly examined, and the known solutions of using power-mismatched pre-amplifiers and transmitters noted. It is then shown that, without loss of transmitter efficiency, a high effective impedance may be created in series with each coil in the array by the use of Cartesian negative feedback. A bench experiment is described that confirms the theory. The solution is also viable for signal reception and is more efficacious than pre-amplifier damping, albeit over a smaller bandwidth.     

The high dependence of polarization resolved laser-induced breakdown spectroscopy on experimental conditions

It is shown that the continuum emission produced by an Al alloy ablated by femtosecond laser pulses is much more polarized than the characteristic lines of elements. A Glan-Thomson polarizer is used in the laser-induced breakdown spectroscopy experiment to investigate the polarization effect. The use of the polarizer at its minimal transmission increases the signal-to-noise ratio. The effects of angle of detection, focal position, and pulse energy on the signal-to-noise ratio are also studied.     

重复频率激光辐照涂层金属材料的温升

 测量了重复频率YAG激光辐照涂层金属材料(30CrMnSiA钢和LF6M铝金壳体)的前后表面温度, 分析了不同频率激光辐照涂层壳体材料的温升特性。实验结果表明:在相同平均功率的条件下, 激光脉冲频率越高, 对材料的加热效率越明显, 重复频率激光对材料的加热优于连续激光。     

纵横波测已紧固螺栓轴向应力

本提出了用纵横波声时测已紧固螺栓轴向应力的一种新方法,解决了用超声精确地测已紧固螺栓应力问题,并且利用超声波沿轴向传播的波速同轴向应力以及三阶弹性常数的关系导出了螺栓应力同其材料声速特性、夹紧距离、温度及纵、横波声时的一种新关系,考虑了受应力作用时温度对声速的影响,简化了测量及计算过程,本还介绍了材料的声速特性实验及测量方法;实验结果表明应力低于２５０ＭＰａ,夹紧距离大于３０ｍｍ时,应力超声测     

The application of regularization technique based on partial optimization in the nearfield acoustic holography

The regularization technique for stabilizing the reconstruction based on the nearfield acoustic holography(NAH) was investigated on the basis of the equivalent source method.In order to obtain higher regularization effect,a regularization method based on the idea of partial optimization was proposed,which inherits the advantages of the Tikhonov and another regularization method—truncated singular value decomposition(TSVD).Through the numerical simulation,it is proved that the proposed method is stabler than the Tikhonov,and more precise than the TSVD.Finally the validity and the feasibility of the proposed method are demonstrated by an experiment carried out in a semi-anechoic room with two speakers.     

The crystal change and "excess heat" produced by long time electrolysis of heavy water with titanium cathode

According to the theory given in the paper[1], the long time electrolysis experiment with titanium cathode in heavy water (D2O) were done for many times by using the open-loop multi-parameters electrolysis calorimetry system, which is established by us. The specialty is that the cathode is titanium rod and the anode is platinum wire. The early experiment result[3] is still repeated in our recent experiment. The obvious "excess heat" phenomenon can take place only when the electrolysis last more than ten days and amount of "excess heat" increased with the electrolysis time. The "excess heat" can also be obtained from the "boiling to dry" experiment. In the recent experiment, we obtain the results that the amount of "excess heat" is about 3.6 times the input energy, the "excess heat" power is 76.5 W, and the "excess heat" power density is 121.7 W/cm3. After the electrolysis, the crystal structure of the Ti cathode was measured with x-ray diffraction apparatus. We found that the crystal structure of Ti cathode was changed to face-centered cubic structure of TiD2 from its hexagonal structure. This result is in agreement with the Gou's theory mentioned in reference[1].     

微机在用刚体转动仪测刚体转动惯量实验中的应用

用刚体转动仪测量刚体转动惯量实验所要测量的主要物理量是时间,所测量的实验数据繁多,且要求准确,而后续的实验数据处理计算复杂。本介绍了一种测量时间、计算转动惯量数值两项工作全部由PC机来完成的新方法。     

自旋1/2-自旋1耦合系统的HSQC和HDQC实验的研究

对自旋1/2-自旋1耦合系统的单量子HSQC和双量子HDQC脉冲序列进行了理论和实验的探讨. 研究结果表明,文献提出的HDQC实验中实际上还发生了零量子跃迁,因此该实验应该是多量子HMQC实验. 研究结果还表明,HSQC有比HDQC更高的灵敏度.     

单压吸收式制冷气泡泵冷态实验及性能分析

单压吸收式制冷是一种可以利用太阳能等低品位能源驱动的制冷循环,而气泡泵是该制冷系统中的最主要耗能部件,因此对气泡泵的研究尤其重要。冷态模拟实验可以避免热态实验中出现的实验过程不稳定等缺点,产生的气泡更加均匀,获得的实验数据更加准确。实验结果表明输气量和沉浸比对气泡泵性能影响较大。     

教学用自组式傅里叶变换光谱仪

对原有的傅里叶变换光谱实验进行了全面的升级改造，研制了一种新型的教学用自组式傅里叶变换光谱仪，波长精度较原有实验提高了两个数量级，由该仪器构成的傅里叶变换光谱实验内涵丰富，不但可以使学生学习一种重要的光谱技术，更可以很好地培养学生综合运用所学知识解决实际问题的能力。     

The role of envelope fluctuations in an apparent demonstration of suppression in simultaneous masking.

Fastl and Bechly [J. Acoust. Soc. Am. 74, 754-757 (1983)] reported that the threshold of a brief 900-Hz signal simultaneously masked by a band of noise. 100 Hz wide, centered at 1000 Hz, was reduced by approximately 8 dB by the addition of an 1150-Hz tone having a level of 20 dB above that of the narrow-band masker. They concluded that this decrease in threshold was a demonstration of suppression in simultaneous masking. Here it is argued that Fastl and Bechly's results simply reflect the poorer detectability of signals masked by higher-frequency fluctuating maskers (their narrow-band masker) than by relatively flat-envelope maskers (their composite narrow-band plus tonal masker). The results of three experiments support the masker-envelope explanation. In the first experiment, as in the report of Fastl and Bechly, the masker centered at 1000 Hz (M1) was a narrow-band noise and the masker centered at 1150 Hz (M2) was a tone. Fastl and Bechly's result was replicated. However, thresholds obtained when M1 was presented alone (the M1-only condition) were more affected by the starting level of the signal within each adaptive track than were thresholds obtained when M1 and M2 were presented together (the M1+M2 condition). This result paralleled a previous report that starting level influenced performance more with fluctuating than with flat-envelope maskers. For the four of seven subjects wh showed learning, there was also more improvement in the M1-only than in the M1 + M2 condition. In the second experiment, M1 was a tone and M2 was a narrow-band noise.(ABSTRACT TRUNCATED AT 250 WORDS)