静脉输液过程中患者肺底部出现移动性湿啰音的临床观察

目的观察患者在静脉输液过程中肺底部出现移动性湿啰音与左心功能之间关系。方法对在静脉输液过程中肺底部出现移动性湿性啰音52例患者,观察其主要症状和体征变化,采用超声心动图测定其心功能。结果超声心动图检查发现46(88.5%)例存在左心功能不全,其中,单纯性舒张功能不全43例(82.7%),左心舒张功能不全合并收缩功能不全3例(5.8%)。结论静脉输液过程中出现的肺底部湿性啰音提示心功能不全存在,有助于心脏疾病的早期发现和早期诊断,减少液体输入量、减慢液体输入速度能防止肺水肿的发生。

用户行为特征背景下抖音短视频App的运营模式和发展趋势研究

目前,抖音短视频App已成为移动短视频中用户群体最多的一个App,它的发展规律和特征对已有移动端视频有很大的借鉴意义。大数据发现,不同性别的用户使用抖音短视频App的原因和观看的内容存在差异;年龄与用户使用满意度和使用频率成反比关系;学历与使用满意度呈负相关关系;企业管理人员在使用抖音短视频App时更注重内容的目的性和功能性。文章分析了抖音短视频App发展现状及基本功能和用户群体使用特征,预测抖音短视频App发展趋势。

上海大剧院观众厅使用效果评析

上海率先在我国建成第一座具有国际水平的现代化大剧院。作者对该剧院及设计单位进行了多次访问调研。文章扼要地介绍该剧院观众厅的视线设计、噪声控制、音质设计、声学参数的实测结果以及所采用的可移动音罩、可调混响装置等技术措施 ,并引用了国内外戏剧界。

Improved mean-shift-based pitch determination

The underlying principle of pitch determination based on the mean shift algorithm is studied, and the cause of pitch error propagation in the original pseudo code is analyzed. The problem of error propagation is solved by choosing an appropriate initial pitch candidate F00. The theoretical choice guideline in a pitch epoch is obtained as ensuring the true pitch F0 satisfying F00/2 〈 F0 〈 3F00/2. The validity of the choice guideline is verified by the F00 experiment. Meanwhile, the algorithm is extended to the pitch determination in the noisy case and compared with the method of subharmonic-to-harmonic ratio （SHR）. The experimental results show that the improved algorithm bears comparison with SHR and it runs much faster than SHR.

MP3播放器走向消亡:受智能手机冲击严重

MP3播放器走向消亡:受智能手机冲击严重10年前刚刚问世时,MP3播放器是数字革命的先锋。然而,随着消费者转向智能手机等其他数码产品,2012年英国市场上iPod和其他MP3播放器的销量大幅下降。根据市场研究公司Mintel的数据,2012年,英国市场MP3播放器的销售额为3.81亿英镑,较2011年减少1.1亿英镑,下滑22%。Mintel预计,到2017年。

Beyond Parroting:Using English Fun Dubbing to Improve English Oral Performance

The present paper is a response to the current problematic situation of oral English teaching at the tertiary level in China and the increasing popularity of web-based mobile oral English learning in oral English classes.Our paper focuses on the use of mobile-phone-based educational software known as“English Fun Dubbing”(EFD)and its advantages in terms of teaching and learning phonetics and oral English in the college classroom.The starting point was a needs analysis which revealed the lack of practice regarding English speaking.In this study,an action research method was adopted,involving 40 second-year students,who employed“classroom teaching+English Fun Dubbing”model as the intervention.Extensive examples from this model were used to build up a picture of the blended learning processes at work.Several imitation tasks,a conversational activity and a speech-delivering task were designed and implemented.Direct observation and the results of the questionnaire survey provided the evidence of the improvement in the students’oral performance.It is our aim to develop the present project to incorporate oral proficiency.The main results of this action research were reflected in the adjustments in the pedagogical treatment,the changes in the role of the teacher and the student,and the shifts in the students’attitudes towards their learning process.

Velocity Slip and Interfacial Momentum Transfer in the Transient Section of Supersonic Gas-Droplet Two-Phase Flows

Modelling and simulations are conducted on velocity slip and interfacial momentum transfer for supersonic two-pha.se (gas-droplet) flow in the transient section inside and outside a Laval jet(LJ). The initial velocity slip between gas and droplets causes an interfacial momentum transfer flux as high as (2.0-5.0) x 104 Pa. The relaxation time corresponding to this transient process is in the range of 0.015-0.090ms for the two-phase flow formed inside the LJ and less than 0.5ms outside the LJ. It demonstrates the unique performance of this system for application to fast chemical reactions using electrically active media with a lifetime in the order of 1 ms. Through the simulations of the transient processes with initial Mach number Mg from 2.783 to 4.194 at different axial positions inside the LJ, it is found that Mg has the strongest effect on the process. The momentum flux increases as the Mach number decreases. Due to compression by the shock wave at the end of the LJ, the flow pattern becomes two dimensional and viscous outside the LJ. Laser Doppler velocirneter (LDV) measurements of droplet velocities outside the LJ are in reasonably good agreement with the results of the simulation.

ARMA Modelling for Whispered Speech

The Autoregressive Moving Average （ARMA） model for whispered speech is proposed. with normal speech, whispered speech has no fundamental frequency because of the glottis being semi-opened and turbulent flow being created, and formant shifting exists in the lower frequency region due to the narrowing of the tract in the false vocal fold regions and weak acoustic coupling with the aubglottal system. Analysis shows that the effect of the subglottal system is to introduce additional pole-zero pairs into the vocal tract transfer function. Theoretically, the method based on an ARMA process is superior to that based on an AR process in the spectral analysis of the whispered speech. Two methods, the least squared modified Yule-Walker likelihood estimate （LSMY） algorithm and the Frequency-Domain Steiglitz-Mcbide （FDSM） algorithm, are applied to the ARMA mfldel for the whispered speech. The performance evaluation shows that the ARMA model is much more appropriate for representing the whispered speech than the AR model, and the FDSM algorithm provides a name acorate estimation of the whispered speech spectral envelope than the LSMY algorithm with higher conputational complexity.

3D Flow Past Transonic Turbine Cascade SE 1050-Experiment and Numerical Simulations

This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 （known in QNET network as open test case SE1050）. The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic （M2 = 0.8） and at transonic （M2 = 1.2） regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenFOAM and in-house code. Analyses of experimental data and CFD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CFD and experiments agree reasonably well.

Theoretical and experimental investigation on bridge-borne noise under moving high-speed train

Bridge-borne noise pollution caused by train-induced bridge vibration has attracted more and more attentions due to its low-frequency characteristic.In order to investigate the numerical simulation technique of bridge-borne noise and noise reduction methods,a simply supported prestressed concrete (PC) box-girder bridge is adopted for study.Based on train-track-bridge interaction theory,the dynamic response of the bridge under a moving high-speed train is calculated in time-domain and assumed as the sound source of bridge-borne noise.Then bridge-borne noise is estimated according to boundary element method (BEM) in frequency-domain.The time-frequency transform is conducted by fast Fourier transformation (FFT).The validity of the numerical simulation technique is verified through comparison with field measurement results.Furthermore,noise reduction methods are proposed and corresponding effects are discussed.Results show that the proposed numerical simulation method is feasible and accurate in assessing bridge-borne noise.The dominant frequencies of bridge vibration and bridgeborne noise range from 40 Hz to125 Hz and from 31.5 Hz to 100 Hz,respectively.The peak frequency of bridge-borne noise near the bottom plate is 63 Hz.Increasing the thickness of deck plate,adjusting the inclination of webs to 0°-12°,strengthening the boundary constraints and adding a longitudinal clapboard are very effective noise control measures.