LIVE TOOLS数字微波系统在新闻直播中的应用

介绍了新闻直播的传输方式．LIVE TOOLS数字微波系统的构成和特点．微波系统在新闻直播上的实际应用，总结在安装调试中的经验和教训。     

A simple novel and fast computational model for the LIVE-L4

The LIVE-L4 test was conducted to investigate the transient and steady state behavior of the molten pool and the crust influenced by different heat generation rates. The main purpose of this work is to develop a simple novel model of the LIVE code to calculate the entire process of the LIVE-L4 test after the melt of KNO₃–NaNO₃ poured into the test vessel. The LIVE code is a transient code and can be used as a fast computational program to calculate the LIVE tests. Natural convection heat transfer in the melt pool, crust behavior, heat conduction in the vessel wall, and radiative heat transfer were all considered in the model of the LIVE code.In the LIVE code, Asfia–Dhir correlations were used to calculate average and local heat transfer coefficients in the melt pool. With the assumption of no considering the composition change of local melt at melt/crust interface, many important parameters, including the melt pool temperature, heat flux distribution along the vessel wall, the thickness of the crust in steady state, and crust growth rate during the test, were calculated and compared with the LIVE-L4 experimental data.The melt pool Nu calculated by the LIVE code is larger than experimental data due to the use of Asfia–Dhir correlation in the LIVE code, which caused the average heat flux through the vessel wall larger than experiment data except the heating phase of 5 kW. It is attributed that the temperature difference between the melt pool temperature and the interface temperature at melt/crust measured in the test is larger than that calculated by the LIVE code due to the constant interface temperature at melt/crust of 284 °C used in the LIVE code. Crust growth rate calculated by the LIVE code was consistent well with the experiment data. Calculation results indicated that the LIVE code could generally predict the main parameters of the melt and crust well during the LIVE-L4 test.     

不同温度及厌氧/好氧运行条件对聚磷菌衰减特性的影响

以富含90％±2％纯度聚磷菌(PAOs)的强化生物除磷系统(EBPR)为研究对象,考察了10℃厌氧、10℃好氧、20℃厌氧、20℃好氧4种运行条件下PAOs的衰减特征.结果表明:温度越高对应衰减速率越快,4个系统在1～9 d里衰减速率的平均值分别为:10℃厌氧:0.053/d; 10℃好氧:0.050/d;20℃厌氧:0.072/d;20℃好氧:0.145/d.其中4个系统由于细胞死亡引起的活性衰减速率分别为:10℃厌氧:0.019/d;10℃好氧:0.017/d;20℃厌氧:0.019/d;20℃好氧:0.03/d,占总活性衰减的比例分别为:35.8％、34％、26.4％、20.7％.在9d饥饿衰减期间,污泥中所含PHA与糖原的量总体呈下降趋势.相同温度下,糖原在厌氧衰减过程中降解速率大于好氧;在同样的厌氧、好氧衰减条件下,温度越高糖原降解速率越快.     

基于Hi3516A的H265码流实时传输系统设计

介绍了在海思Hi3616A开发平台下实现的一种H265码流实时传输系统。利用海思提供的媒体处理平台(MPP)采集高清摄像头感应到的视频图像并进行H265压缩编码,然后对LIVE555开源代码进行二次开发,实现播放H265实时码流的功能,将压缩编码后的数据发送出去。设计结果表明,系统传输高清视频图像延迟短,播放流畅,满足智能监控领域应用的要求。     

应用荧光光谱法研究污泥活性变化

本研究以LIVE/DEAD Baclight染色法测定活性污泥中的活菌水平以表征其活性,采用荧光染色剂SYTO!9和碘化丙啶（PI）对活性污泥进行染色,并利用日立F-7000荧光分光光度计测量其绿色荧光（Fg,波长500—510 nm）强度来表征活性污泥中活菌水平。该法直接对稀释后的污泥悬浊液进行测量,简化了测量步骤。通过纯菌E.coli的LIVE/DEAD染色试验,发现活菌比例与绿色/红色荧光的比值存在较高的相关性,相关系数R2=0.982。通过污泥衰减试验发现,污泥衰减7天后,激发波长485nm处绿光/红光的比值分别由3.69降为了1.74,活菌所占比例下降了52.85%,同时用软件灰度分析法计算污泥衰减后活菌比例下降了55.14%,两种方法所得结果较为接近。     

熔融池相变传热特性的大涡模拟数值研究

研究反应堆熔融池内部的流动与传热特性对保证熔融物堆内滞留具有重要意义。本文基于开源软件OpenFOAM平台,结合大涡模拟湍流方法和熔融池相变过程建立熔融池传热模型,针对典型熔融池传热实验LIVE工况开展数值计算,得到了熔融池内速度场和温度场以及下封头内壁面硬壳厚度和热流密度分布情况。结果表明,熔融池内速度、温度和热流密度随高度或径向角度的增大而增大;硬壳厚度随径向角度的增大而减小;下封头壁面上的热负荷在顶部聚集。传热参数计算结果与实验数据整体符合较好,可以有效反映出熔融池内自然对流与相变过程,验证了计算模型的可靠性,可为进一步研究熔融池相变传热特性提供参考。      

Effect of polishing method on surface roughness and bacterial adhesion of zirconia-porcelain veneer

The purpose of this study was to evaluate the effect of various polishing methods on surface roughness of zirconia-porcelain veneer and to correlate the findings with early bacterial adhesion. The study specimens were glazed (control group), glazed after fine polishing (glazed group) and polished with Exa Cerapol (Cerapol group) or with Shofu porcelain adjustment kit (Shofu group) (n =20). Surface roughness was then measured using profilometer and scanning electron microscope (SEM). After artificial saliva coating, the specimens were incubated in Streptococcus mitis suspension for 4 h at 37 °C. Adherent bacteria were quantified from SEM images. Streptococcal viability was assessed by LIVE/DEAD staining kit and fluorescent microscope. There were significant differences in surface roughness according to polishing method and surface material. Relatively smoother surfaces were found in zirconia surfaces and glazed porcelain surfaces. There were also significant differences in bacterial adhesion according to polishing method and surface material. Cerapol group showed minimal bacterial adhesion with more dead cells when compared to other groups. A positive correlation between surface roughness and bacterial adhesion was found in glazed porcelain surface and a negative correlation in zirconia surface of Cerapol group, both with no statistical significance. Within the limitations of in vitro study, surface roughness and bacteria adhesion were significantly influenced by polishing method and surface material. Also, there was a positive correlation and negative correlation between surface roughness and bacterial adhesion in glazed porcelain surface and in zirconia surface of Cerapol group, respectively.     

不同温度及厌氧/好氧运行条件对聚磷菌衰减特性的影响

以富含90%±2%纯度聚磷菌（PAOs）的强化生物除磷系统（EBPR）为研究对象,考察了10℃厌氧、10℃好氧、20℃厌氧、20℃好氧4种运行条件下PAOs的衰减特征。结果表明：温度越高对应衰减速率越快,4个系统在1~9 d里衰减速率的平均值分别为：10℃厌氧：0.053/d;10℃好氧：0.050/d;20℃厌氧：0.072/d;20℃好氧：0.145/d。其中4个系统由于细胞死亡引起的活性衰减速率分别为：10℃厌氧：0.019/d;10℃好氧：0.017/d;20℃厌氧：0.019/d;20℃好氧：0.03/d,占总活性衰减的比例分别为：35.8%、34%、26.4%、20.7%。在9 d饥饿衰减期间,污泥中所含PHA与糖原的量总体呈下降趋势。相同温度下,糖原在厌氧衰减过程中降解速率大于好氧;在同样的厌氧、好氧衰减条件下,温度越高糖原降解速率越快。     

Study effects of the kinetics of local composition diffusion on the melt pool coolability by developing a DBL-LIVE model

The LIVE-L4 test was conducted to investigate the transient and steady state behavior of the molten pool and the crust influenced by different heat generation rate. In previous work, a simple novel model of the LIVE code was developed to simulate the entire process of the LIVE-L4 test after the melt of KNO₃NaNO₃ poured into the test vessel. The LIVE code is a transient code and can be used as a fast computational program to simulate the LIVE tests. Calculation results indicated that the LIVE code could generally predict the main parameters of the melt and crust well during the LIVE-L4 test.However, the LIVE code could not predict some processes accurately, such as the early phase of the test after the melt poured into the test vessel, and heat flux distribution at small polar angle, due to no considering the composition change of local melt during the crust formation, which affected the properties of the local melt adjacent to the crust, especially the liquidus temperature of the local melt at the interface of melt and crust. Therefore, considering the effects of the crust growth rate and the diffusion of concentrated NaNO₃ on the composition change of the local melt, the diffusion boundary layer (DBL) model was developed and combined with the LIVE code model to consider the composition change of the local melt during the crust formation, with the assumption of considering a quasi-stable plane front solidification of the melt. The DBL-LIVE code was used to calculate the characteristics of the melt and the crust during the heating phase 18 kW. The calculation results indicated that the DBL-LIVE code could predict the main parameters of the melt and crust much more accurately. It could also predict the transient and steady characteristics of the melt composition. Moreover, the thickness of the diffusion boundary layer has a marked influence on the composition distribution. Therefore, the sensitivity analysis of the DBL thickness was also conducted in this work.     

Linux下语音实时通信的一种实现方法

在设计嵌入式语音通信系统的过程中,提出了一种Linux下语音实时通信方法。利用Linux下OSS内核驱动实现了语音的采集和回放,基于LIVE库实现了RTP／RTCP的音频流的实时传输,并运用Linux下多线程技术,实现了语音的全双工数字通信。调试结果表明,该方法可以快速方便的实现语音的实时传输,对从事相关产品的开发具有一定的参考价值。