大型油罐破裂泄漏特征研究

统计了多起油罐破裂事故,并对油罐破裂特征及油品泄漏流场进行分析。通过事故案例统计,总结了三种典型的油罐破裂形式,得到了油罐易发生破裂的位置及原因。对事故案例后果进行分析,将油罐破裂泄漏过程分为两个阶段,并分别对其流场特性进行研究。以平板流动临界雷诺数为判定准则,对油库常见油品泄漏流动雷诺数进行计算,得出泄漏油品的流态绝大多数为完全发展的湍流。     

Ozone-Bromine Treatment – Water Treatment in Public Pools without Chlorine: A New Standard?

The central task of the rules and regulations governing water treatment in public swimming pools is to provide guidelines, the compliance with which leads to completely hygienic water. For this purpose, DIN 19643 “Treatment of Water of Swimming Pools and Baths” applies in Germany. To date, this standard has prescribed the chlorination of water. In a therapeutic pool introduced here, water was treated without chlorine. The water quality was observed as part of a long-term study over the course of three years. During the entire period, no germs were detected in the filtrate of the system, not even unspecific CFU germs. The treatment presented here is detailed from both theoretical and practical viewpoints. The treatment uses the oxidation power of ozone to form hypobromous acid as a disinfectant in water containing bromide. A crucial aspect of the treatment is the possible formation of bromate. It is shown that the formation of bromate can be suppressed very effectively. Further bromine-based by-products were monitored. Unpleasant by-products as known from the chlorination were not found. The treatment, known as ozone-bromine Treatment, demonstrates new ways to treat water in public swimming pools and should now be incorporated into the German DIN 19643. It is to be expected that this will also be reflected in the national standards of other countries.     

SGSN Pool技术及其在移动网中的应用探讨

简要介绍了SGSN Pool的实现机制、实现意义,对SGSN Pool的技术演进及实现的前提条件进行了分析和阐述。讨论了SGSN Pool技术在容灾中的应用。     

Transport phenomena within the liquid phase of a laboratory-scale circular methanol pool fire

The effects of altering the lower thermal boundary condition of a methanol pool from −5 °C to 50 °C was investigated within a 90 mm diameter and 12 mm deep quartz burner under steady state burning condition in a quiescent air environment. Both the burning rate and the flame height were observed to increase by 15% with increasing bottom temperature over this range of bottom boundary conditions. The temperature and velocity within the liquid were measured by a single thermocouple traversed through the pool and PIV, respectively, in order to better understand the transport of mass and energy in the liquid. Temperature measurements revealed a distinct two-layer vertical thermal structure with the upper layer of the pool being almost uniform and near the boiling temperature of the fuel, while the lower layer experienced an increasing temperature gradient as the bottom boundary temperature was lowered. The thickness of the thermally uniform layer increased as the bottom temperature was increased. The measured fluid velocity showed a complementary two-layer structure with the upper layer being dominated by a pair of counter-rotating vortices that kept this portion of the liquid well mixed and transferred heat from the hot pool wall to the pool center, while the flow in the lower layer was uniformly low in value and vertical. A model was presented to aid in understanding the energy transfer within the liquid phase. In the lower layer, the Peclet Number was in the order of unity and required that the energy transfer throughout the liquid phase to be modeled as a combination of conduction and convection. Using this physical model, the change in burning rate over the full 55 °C change in bottom temperature was predicted within 2%, thereby supporting the proposed mechanism for energy transfer into the pool’s depth.     

Effects of surface wettability on nucleate pool boiling heat transfer for surfactant solutions

Experiments for pool boiling of deionised water and acetone with different surfactant, 95% sodium dodecyl sulfate (SDS), Triton X-100 and octadecylamine, have been conducted under atmospheric pressure to investigate the effect of surface wettability. The boiling curves for different concentrations of surfactant solution on both smooth and roughened surfaces were obtained. The results show that the addition of surfactant can enhance the water boiling heat transfer, and the enhancement is more obvious for SDS solution; but has little influence on the acetone boiling curve. While the roughened surface enhanced the heat transfer for Triton X-100 solution, it also decreased the heat transfer coefficient for SDS solution. All these can be explained by including the changing of surface wettability, which has been neglected for a long time and should be an important parameter influencing boiling heat transfer. By incorporating such effects, the modified Mikic-Rohsenow pool boiling model, we proposed, can predict these experimental data well.     

Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling. Part I: Experimental measurement

Influences of refrigerant-based nanofluid composition and heating condition on the migration of nanoparticles during pool boiling were investigated experimentally. The nanoparticles include Cu (average diameters of 20, 50 and 80 nm), Al and Al₂O₃ (average diameters of 20 nm), and CuO (average diameter of 40 nm). The refrigerants include R113, R141b and n-pentane. The mass fraction of lubricating oil RB68EP is from 0 to 10 wt%, the heat flux is from 10 to 100 kW m⁻², and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results show that the migration ratio of nanoparticles during the pool boiling of refrigerant-based nanofluid increases with the decrease of nanoparticle density, nanoparticle size, dynamic viscosity of refrigerant, mass fraction of lubricating oil or heat flux; while increases with the increase of liquid-phase density of refrigerant or initial liquid-level height.     

Region based foreground segmentation combining color and depth sensors via logarithmic opinion pool decision

In this paper we present a novel foreground segmentation system that combines color and depth sensors information to perform a more complete Bayesian segmentation between foreground and background classes. The system shows a combination of spatial-color and spatial-depth region-based models for the foreground as well as color and depth pixel-wise models for the background in a Logarithmic Opinion Pool decision framework used to correctly combine the likelihoods of each model. A posterior enhancement step based on a trimap analysis is also proposed in order to correct the precision errors that the depth sensor introduces. The results presented in this paper show that our system is robust in front of color and depth camouflage problems between the foreground object and the background, and also improves the segmentation in the area of the objects’ contours by reducing the false positive detections that appear due to the lack of precision of the depth sensors.     

软交换系统MSC Pool改造的研究与应用

软交换系统"大容量、少局所"的建设方式,容灾备份技木在移动软交换网络中变得尤为关键,相对传统的"1+1"、"N+1"备份方式,MSC Pool技术具有多方面的优势,文章结合工程实际情况提出软交换系统MSC Pool改造方案,为同类工程的建设提供理论和技术指导。     

A fortran program for Monte Carlo simulation of oil-field discovery sequences

We have developed a program for performing Monte Carlo simulation of oil-field discovery histories. A synthetic parent population of fields is generated as a finite sample from a distribution of specified form. The discovery sequence then is simulated by sampling without replacement from this parent population in accordance with a probabilistic discovery process model. The program computes a chi-squared deviation between synthetic and actual discovery sequences as a function of the parameters of the discovery process model, the number of fields in the parent population, and the distributional parameters of the parent population. The program employs the three-parameter log gamma model for the distribution of field sizes and employs a two-parameter discovery process model, allowing the simulation of a wide range of scenarios.     

Effect of nanoparticles on CHF enhancement in pool boiling of nano-fluids

To investigate the characteristics of CHF (Critical Heat Flux) enhancement using nano-fluids, pool boiling CHF experiments of two water-based nano-fluids with titania and alumina nanoparticles were performed using electrically heated metal wires under atmospheric pressure. The results showed that the water-based nano-fluids significantly enhanced CHF compared to that of pure water. SEM (Scanning Electron Microscopy) observation subsequent to the pool boiling experiments revealed that a lot of nanoparticles were deposited on heating surface during pool boiling of nano-fluids. In order to investigate the role of the nanoparticle surface coating on CHF enhancement of nano-fluids, pool boiling CHF of pure water was measured using a nanoparticle-coated heater prepared by pool boiling of nano-fluids on a bare heater. It was found that pool boiling of pure water on the naonoparticle-coated heater sufficiently achieved the CHF enhancement of nano-fluids. It is supposed that CHF enhancement in pool boiling of nano-fluids is mainly caused by the nanoparticle coating of the heating surface.