Elevator shaft pressurization for smoke control in tall buildings: The Seattle approach

CONTAM simulations of both commercial and residential tall building models are conducted in order to study recently adopted Seattle code requirements for elevator shaft pressurization systems. In contrast to the International Building Code (IBC) requirements, the Seattle approach specifies across elevator door pressure minimums and maximums on only four “fire floors” (including one above, and two below, the fire floor). This is accomplished using a minimal pressurization of the entire elevator shaft in conjunction with venting of the four fire floors. The present study adresses the feasibility of calibrating such a system to meet the design objectives in tall buildings (system performance during an actual fire event is not considered). The two building models correspond to 37 story buildings with dual elevator and dual stairwell shafts extending the entire height of the building. Each model is calibrated to experimental data. Simulations are conducted for a variety of ambient temperatures and exterior building door positions. Coupled pressurization of the stairwells is also considered. The system requirements are found to be achievable for both elevator only and coupled elevator and stairwell pressurization systems. However, the observed pressure differences do change with changes in the ambient temperature as well as changes in the ground floor exterior door position. It is therefore recommended that such systems should be calibrated for pressure differences intermediate to the prescribed minimum and maximum values to compensate for changes to the system performance. Providing a relief vent to ambient on any recall floor may also be advisable.     

气田增压开采方案的灰色综合优选

气田增压开采方案涉及工艺、经济、环境等多方面因素,为了对其进行全面、科学的评价,建立了气田增压开采方案综合评价多层次指标结构体系,通过灰色关联分析法和层次分析法相结合,形成了多层次灰色关联分析法。基于该方法建立了增压开采方案多层次综合评价数学模型,给出了在我国华北某气田的应用实例。结果表明,该方法具有层次清晰、计算简单的特点,评价结果真实可靠,能够对气田增压开采方案进行切实可行的综合评价。     

四聚乙醛生产解聚工艺改进研究

对四聚乙醛（熔点246.2℃）生产中副产物三聚乙醛（熔点12.5℃）的解聚工艺进行研究改进。将常压间歇法改为加压连续法,既节能降耗,又减少污染,获得了显著的经济效益。     

Analysis of superplastic blow-forming in a conical closed die

A mathematical model using the finite-difference method has been proposed in this work to examine the plastic deformation behavior of the sheet during blow-forming in a conical closed die. In the formulation of this mathematical model, nonuniform thinning in the free bulged region and the contact condition including the sticking and sliding friction modes between the sheet and die are considered. Effects of various forming parameters such as the die entry radius, friction coefficient, inclined angle of the die, etc., upon the optimized pressurization profile, forming time and the thickness distribution of products were discussed systematically. Furthermore, experiments on superplastic blow-forming in a conical closed die were carried out using 8090 Al-Li sheets. It is found that the theoretical predictions agree with experimental results. The thickness distributions of the SPF-ed product obtained with different friction coefficients along the die entry, sidewall and bottom are closer to the experimental data than those obtained with a constant friction coefficient.     

铝合金汽车汽缸体局部增压铸造技术研究

以过共晶B390铝合金汽车汽缸体为对象,研究了挤压铸造-局部增压铸造过程中的增压起始时间和增压压入量对铸件组织的影响。结果表明,通过在汽缸体厚壁热节处设置增压通道实施局部增压,采用10s的增压起始时间和20mm的增压压入量,很好地解决厚壁处易产生缩松、缩孔等缺陷的问题。制造的汽缸体经T6热处理后,铸件抗拉强度、硬度(HB)和伸长率分别达到305MPa、137和4.8%,随机抽取的试样通过了1.38MPa的卤素气体检漏试验。     

Comparison of three computational models for predicting pressurization characteristics of cryogenic tank during discharge

In order to select an effective approach to predict the pressurization characteristics of cryogenic tank during rocket launching, three computational models, defined as 0-D, 1-D and CFD models, are used to obtain the pressure evolution and thermal performance of a cryogenic tank during pressurized discharge period. Several pressurization cases are computed by all of the three models to evaluate their predictive abilities and effects, respectively. The comparative study shows that for the case with a diffuser-type injector at the tank inlet, the consistent results by the three models are obtained in the most of period, except that 1-D model has a peak departure prediction of pressure value at the beginning of process. All of the three models can be used to predict the pressurization performance, and their predictive abilities could be validated with one another. The CFD model is the unique suitable model to display the pressurization performance including physical distribution in radial direction especially for the system with no-diffuser-type injector. Based on the analysis, the application selection of three models for different cases is accomplished. The 0-D model is the priority selection for a simple pressure prediction of tank ullage, even for the situation that severe temperature distribution exists in the ullage range. The 1-D model is the optimal selection as considering both the convenience and the time consumption for the constant-pressure cases. But it is not recommended in a constant-inlet flux cases for its distinct predicting deviation at the beginning of the process. When the detailed distributions within the tank are concerned, the CFD model is the unique selection. The results of this paper may be beneficial to the model selection and optimization analysis of a pressurization system.     

Effects of High Pressure and Heat Treatment on Pectic Substances and Related Characteristics in Guava Juice

Effects of high pressure treatment on guava juice pectic substances and related juice characteristics were investigated and compared with heat treatment. The viscosity and turbidity of guava juice pressurized at 600 MPa and 25°C for 10 min increased slightly; whereas the viscosity of juice heated at 95°C for 5 min decreased while turbidity increased. There were no apparent changes in water soluble, oxalate soluble and alkali soluble pectin in pressurized juice. However, heat treatment of juice decreased water and alkali soluble pectins and slightly increased oxalate soluble pectin. High pressure treatment resulted in no marked changes in pectic and cloud substances of guava juice, and maintained the natural viscous of the juice.     

压给料泵炸泵问题分析

论述了加压过滤机给料泵在仓内压力作用下矿浆高速倒灌入泵体内，可造成泵体严重损坏，提出改进方案，经过改进，再无发生炸泵现象。     

一种新型无缝三通成型工艺技术

本文介绍的三通成型新工艺是以无缝钢管作管坯、以天然气－氧气混合气体为燃料，利用瓦形气体火焰加热图将管坯局部加热，然后在专用设备上对管坯进行推压热拔而一次成型工艺技术。这种新工艺特别适合在有天然气源的施工单位推广应用，其产品的优点是铸造成焊接三通所难以相比的。     

On the plant-specific impact of different pressurization rates in the estimation of containment failure mode probabilities

The explicit consideration of different pressurization rates (e.g. fast and slow) in estimating the probabilities of containment failure modes (e.g. leak, rupture, and/or catastrophic rupture) might have a profound effect on the confidence of the containment performance evaluation that is so critical for risk assessment of nuclear power plants. We have performed a bounding analysis for the impact of different pressurization rates on the leak and rupture mode probabilities using models for fast and slow pressurizations. The present models are based on the evaluations of probability distributions that are characterized with the median pressures and their standard deviations, for individual mechanisms of structural failure modes and the nominal break sizes. As a result, we have obtained a quantitative and plant-specific estimate of the impact of the pressurization rates on the leak and rupture containment failure probabilities. The present study showed that the impact was not significant for the specific cases considered in this study and confirmed that the treatment used in the specific cases was conservative.