High-Modulus Columns for Liquefaction Mitigation

This paper presents the performance of a shopping complex in Turkey where the soils were improved with jet-grout columns and preload fills and subjected to the 1999 Kocaeli Earthquake (M = 7.4). Under construction at the time of the earthquake, the Carrefour Shopping Center covers an area of 55,000?m2 and is founded on shallow footings, mats, and slabs-on-grade that rest on soft, saturated alluvial sediments consisting of clays, silts, and sands. High-modulus columns constructed by jet grouting were installed at close-to-moderate spacings to reduce anticipated static settlements in the clays and mitigate liquefaction in the sands. The site was subjected to a peak acceleration of approximately 0.2g during the earthquake. Grouting had been completed for about two-thirds of the site when the earthquake struck. Following the event, a field reconnaissance found stark contrast between the performance of the improved and unimproved sections. The jet-grout-treated areas suffered no apparent damage, whereas the unimproved sections of the complex, along with nearby untreated building sites, commonly suffered liquefaction-related settlements of up to 10 cm. This is the only case history known to the authors that documents the field performance of high-modulus columns used in this manner for liquefaction mitigation and direct instrumented measurement of liquefaction-induced settlements.     

采用径向射流冲击与钎焊砂轮解决磨削烧伤的研究

在分析高效磨削烧伤机理的基础上，提出了两项对策：一是采用高压径向射流冲击强化磨削弧区换热，以最大限度地疏导已经产生的积聚在弧区的磨削热；二是采用钎焊超硬磨料砂轮取代传统电镀砂轮，以提高砂轮的锋利度降低磨削比能，减少磨削热的产生。缓进给断续磨削试验结果表明，该两项对策对解决难加工材料磨削烧伤问题效果十分明显，具有广阔的应用前景。     

基于MEMS技术的新型微冷却方式

针对高功率电子器件散热问题,介绍了国际前沿领域电子设备热控制的技术动态．讨论了基于MEMS技术的微冷却器有体积小,散热面积大,消耗功率低,批量制作经济性好等优点。分析了微通道、微喷流和微热管3种基于MEMS技术的新型微冷却方式的传热原理、目前的技术状况及应用前景微通道的采用增加了对流换热面积,提高了对流换热系数;微喷流冷却器中由于高速冷却液的形成,显著提高了换热系数;微热管均热效果极佳。     

Intensified hydroformylation as an example for flexible intermediates production

One of the future challenges for chemical engineering is the design of flexible plants allowing an adaptation of production output to market development. Consequently, the target for the design of new processes must be the identification of equipment allowing such an expansion close to market development. To leverage the full benefit of this approach flexibility analysis has to be integrated into process design workflow. In this article the conventional technology for hydroformylation is compared to an intensified process design. This new design consists of a jet loop reactor followed by a membrane section to separate and recycle the homogenous catalyst. In the first part of the article it will be shown that process intensification leads to a net present value improvement of 30% compared to state of the art hydroformylation at a capacity of 100 kt/a. In the second part suitability of the intensified process for a stepwise plant expansion will be demonstrated. In an expansion scenario with two steps equivalent annual annuity is increased by 5% compared to a one step investment.     

破口事故比例模拟中安全壳破口源项参数评估研究

采用基于破口总焓相似、强迫射流及浮力羽流流场相似及传热传质过程相似的多约束分析体系,归纳与质能源项相关的传热传质过程、耗散过程以及自然循环过程的时间尺度,确定模拟实验源项满足的各种模拟工况所必须遵循的设计约束条件。分析表明,自然循环过程时间常数是约束不同物理过程最重要的基础参数,也是模拟装置设计的基本约束参数。给出适用于确定安全壳破口源项试验参数的计算关系式,用于计算获得试验装置的几何参数和试验边界条件。     

Non-contact measurements of water jet spreading width with a laser instrument

Jet spreading width is one of the important characteristics of water jets discharging into the air. Many researchers have dealt with measuring this width, and contact measuring methods on the water jet surface were employed in a lot of the cases. In order to avoid undesirable effects caused by the contact on the jet surface, we introduce non-contact measuring methods with a laser instrument to the measurements of jet spreading width. In measurements, a transmitter emits sheet-like laser beam to a receiver. The water jet between the transmitter and the receiver interrupts the laser beam and makes a shadow. The minimum and maximum values of the shadow width are measured. In addition, pictures of the water jet are taken with a scale, and the shadow width is measured from the pictures. The experiments on various needle strokes were performed. Three kinds of width consistent with the jet structure were obtained. In the results, it can be concluded that our non-contact measuring methods are feasible. The data of jet spreading widths and jet taper were obtained and are useful for future applications.     

GSI-191问题喷射冲击影响区域的计算分析

在压水堆LOCA(Loss of Coolant Accident)事故之后,高能管道流体喷射冲击导致破口附近的保温层等材料破裂为碎片。这些碎片随流体在安全壳内传输并在地坑滤网沉积形成碎片床,阻碍应急堆芯冷却系统的正常运行。部分碎片可能旁通滤网进入反应堆压力容器,从而引起一系列的效应。该问题被称之为GSI-191(Generic Safety Issue-191)问题。为解决GSI-191问题,首先需要确定破口附近产生的碎片量。当前研究基于ANSI/ANS58.2-1988标准和等效体积球体模型,自主开发了喷射冲击影响区域计算工具JETZOI。采用该工具计算获得的NEI(Nuclear Energy Institute)算例的喷射轮廓和等压线与美国核管会(United States Nuclear Regulatory Commission,U.S NRC)的结果符合很好,从而实现了对NEI算例的成功复现。进一步进行了不同滞止工况的敏感性分析。分析结果表明,在相同的滞止压力下,流体温度的升高将导致影响区域破坏半径的减小和碎片量的减少。因此在开展喷射冲击试验获得影响区域的破坏半径时,应当保守选取冷段双端断裂作为极限工况以使喷射冲击产生的碎片量最大。     

An autothermal reforming system for diesel and jet fuel with quick start-up capability

A quick, low energy consuming and reliable start-up is essential for fuel cell systems utilizing diesel and jet fuel. A compact fuel processor for coupling with a high-temperature polymer electrolyte fuel cell is developed with electrically-heated reactors in the 28 kW_th power class. Based on this set-up, start-up strategies are developed and validated. With the basic strategy, 14 min are required in the best case to commence reforming and achieve self-sustaining operation with desired CO concentration at full load using NExBTL diesel and, respectively, 16 min using Jet A-1. However, using premium diesel, the basic strategy leads to a strong increase in the concentrations of ethane and benzene. An advanced strategy enables 16 min start time with premium diesel suppressing these undesired side products. This result is within the 30 min start-up time target for auxiliary power units for 2020 and offers a reliable option for real world applications.     

Techno-economic analysis of a bio-refinery process for producing Hydro-processed Renewable Jet fuel from Jatropha

HRJ (Hydro-processed Renewable Jet) conversion technology has been recently used to produce renewable jet fuel for commercial or military flights. In this study, a techno-economic analysis is carried out for evaluating the production of jatropha-derived HRJ fuel through a bio-refinery process. Each component of the chosen feedstock jatropha can be converted into valuable products. The bio-refinery process is split into 6 parts: (1) Fruit Dehulling; (2) Shell Combustion; (3) Oil Extraction; (4) Press Cake Pyrolysis; (5) Oil Upgrading; (6) Product Separation. The minimum jet fuel selling price (MJSP) from this fruit scenario is calculated to be $5.42/gal based on the plant capacity of 2400 metric tonne of feedstock per day. The co-products obtained from the process not only significantly deduct the production cost but make the entire process energy self-sustainable. We also discuss the oil scenario, which oil is the starting material and the process begins from Oil Upgrading section. The oil scenario offers the MJSP of $5.74/gal with lower capital but higher operating costs. The differences of MJSPs for fruit and oil scenarios are due to feedstock cost, refinery capital cost, co-product credits and energy cost. Based on the sensitivity analysis, the feedstock price, oil content, plant capacity, reactor construction and catalyst usage are important parameters that control the price of the produced fuel.