Gas-cooled reactor thermal hydraulic analyses with MELCOR

Pursuant to the Energy Policy Act of 2005, the High Temperature Gas-Cooled Reactor (HTGR) has been selected as the reference design for the Next Generation Nuclear Plant (NGNP). Stemming from a U.S. Nuclear Regulatory Commission (NRC) HTGR research initiative, a need was identified for validation of systems-level computer code modeling capabilities in anticipation of the eventual need to perform licensing analyses. Because the NRC has used MELCOR for light water reactors (LWR) in the past and because MELCOR was recently updated to include gas-cooled reactor (GCR) physics models, MELCOR is among the system codes of interest to the NRC. This paper describes MELCOR modeling of the General Atomics' Modular High Temperature Gas-Cooled Reactor (MHTGR). The MHGTR is a suitable design for demonstration of MELCOR GCR modeling competency for two reasons: 1) the MHTGR is a predecessor to the more advanced General Atomics’ Gas-Turbine Modular High Temperature Reactor (GTMHR), and 2) experimental data useful for benchmark calculations may soon become available. Using the most complete literature references available for the MHTGR design, researchers at Texas A&M University (TAMU) constructed a MELCOR input deck for the MHTGR to partially validate MELCOR GCR modeling capabilities. Normal and off-normal system operating conditions were modeled with appropriate boundary and initial conditions. MELCOR predictions of system response were obtained for steady-state, pressurized conduction cool-down (PCC), and depressurized conduction cool-down (DCC) scenarios. Code results were checked against nominal MHTGR design parameters, physical intuition, and anticipated GCR thermal hydraulic response. No inherent deficiencies in MELCOR modeling capability were observed, suggesting that the newly-implemented GCR models are adequate for systems-level analysis. If and when experimental benchmark data becomes available, further validation activities may proceed given the modeling efforts discussed herein.     

Ni-V负载酸改性焙烧高岭土的制备、表征及光催化性能

高岭土在773 K焙烧,经H2SO4溶液处理后作为载体,在不同n(Ni2+)∶n(V5+)溶液中浸渍制备了Ni-V负载酸改性焙烧高岭土样品,并利用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、吡啶吸附FTIR(Py-FTIR)和紫外-可见光漫反射光谱(UV-Vis)对样品进行了表征。在高压汞灯下,以甲醇(CH3OH)常压转化制二甲醚(CH3OCH3)为模型反应,评价了Ni-V负载样品的光催化活性。结果表明,所制备催化剂对CH3OH的光催化转化有活性。当处理焙烧高岭土的酸溶液中H2SO4质量分数为40%、浸渍液n(Ni2+)∶n(V5+)=2∶8、样品焙烧温度为773 K时,催化剂样品对CH3OH转化反应活性最高,CH3OH转化率为30.5%,CH3OCH3选择性为76.2%。样品Ni-V的协同作用和表面酸性是促进CH3OH光催化转化制备CH3OCH3反应活性的重要影响因素。     

热轧管深孔镗滚加工的走偏问题剖析与结构优化

为控制孔轴线的偏斜,提高孔轴线的直线度精度,降低废品率,剖析了深孔镗滚加工中刀具走偏的根本原因,提出了合理设置刀具参数、提高刀具装配精度和支承刚度、优化支承套结构等措施,从而改善了加工质量,获得了较为满意的结果。     

On the application of concentrated solution theory to the forced convective flow of excess supporting electrolyte

A recent model for electrolysis with forced convection in a channel and an excess of dilute supporting electrolyte is extended using concentrated solution theory. Mean Spherical Approximation theory is used to calculate the necessary Onsager coefficients and ionic activities. Using asymptotic methods, we demonstrate the surprising similarities between the leading order equations for the dilute and concentrated theories. In addition, in deriving the extension, certain omissions in the original work are highlighted: an oversight in the Butler-Volmer law used in the original work is corrected, and the systematic use of similarity-like variables in electrochemical problems that do not have a similarity solution along the entire length of the diffusion layer adjacent to an electrode is demonstrated. This helps to explain the manner in which the solutions for the anode and cathode boundary layers and the bulk region decouple from each other at limiting current, enabling a much simpler solution strategy.     

Effects of supporting electrolyte on galvanic deposition of Cu2O crystals

The effects of introduced supporting electrolyte on the galvanic deposition of Cu₂O crystals have been investigated using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD). The results show that the chemical nature of supporting electrolytes plays very important roles in the galvanic deposition of Cu₂O crystals. The chloride stabilizes the (1 0 0) planes of Cu₂O crystals, resulting in the formation of cubic crystals, while nitrate, sulfate and fluoride stabilize the (1 1 1) planes of Cu₂O crystals, leading to the deposition of truncated octahedral and octahedral Cu₂O crystals. It provides a facile way to control the morphology of galvanically obtained Cu₂O crystals by indirectly adjusting the inorganic adsorption agents.     

支承板三平行销轴钢套定位方法及实践

对汽车单顶缸自卸支承板的制作， 及其三平行销轴钢套采用的假轴帮助确定其位置并消除焊接应力与焊接变形的定位方法，以及钢套钻镗孔的加工进行了介绍。     

Anodic acyloxylation based on the acid–base reactions between acetic acid or trifluoroacetic acid and solid-supported bases

We have developed a novel electrolytic system for anodic acyloxylation based on the acid–base reactions between acetic acid or trifluoroacetic acid and solid-supported bases. On the basis of the electrolytic system, anodic acyloxylation of organic compounds, which even have considerably high oxidation potentials, was successfully carried out to provide the corresponding acyloxylated products in moderate to excellent yields. Furthermore, it was found that silica gel supported bases are not only chemically stable under acidic conditions but also electrochemically stable and thus reusable for many times.     

Retracted: A study of a B2C supporting interface design system for the elderly

People are now living longer because of advances in medical science, resulting in the percentage of the elderly in the population increasing year by year. These older individuals cannot move about like youngsters do. Internet shopping could become one of the most important shopping channels for them. According to related domestic and foreign survey results, this is confirmed by the increased percentage of elderly Internet shoppers. A lot of consumers, however, are still not satisfied with their Internet shopping experiences. Many have had the experience of giving up before completing the purchasing procedure. The key factors included in such procedures are rather complex, and user interfaces are not necessarily well‐designed. Nowadays, most websites are still designed for the convenience of the seller instead of the consumers. Often consumers find that their interfaces are complex and hard to use and that they require a high mental workload. Based on the behavioral model of older Internet consumers and difficulties they have encountered, and after exploring the information provided by shopping websites and evaluating the status of their current interface design, this study proposes an example of a supporting interface design system (SIDS) for the elderly. The effects of the SIDS are verified experimentally. A total of 12 subjects participated in the experiment. The results showed that the SIDS could successfully reduce the time spent by the elderly subjects on inputting data during the shopping process and the number of repetitions and the time spent on searching for, examining, and comparing products. Furthermore, it was also helpful to reduce the mental workload caused by Internet shopping. © 2012 Wiley Periodicals, Inc.     

Scaffolding student-generated questions: Design and development of a customizable online learning system

Despite the fact that the benefits of student question generation are well documented, most students do not take part in question generation exercises during their formal schooling and are not accustomed to authoring questions. Under the premise that student question generation activities should be better supported in a timely, flexible and logistically feasible fashion, a customizable online learning environment that accentuates various scaffolding techniques has been designed and developed. The framework guiding the development of the system, and its associated designs, are described. To assess the various built-in scaffolds used to support students’ learning activities by means of question generation, a study was undertaken to that measured students’ perceived usefulness of each mechanism, as well as the effects of the perceived usefulness of the scaffolds on students’ attitudes toward question generation learning activities in general. The data collected indicated that, by utilizing computers and network technologies, the developed system provided a supportive learning environment for student’s question generation learning activities. Support features not yet included in other similar systems (including access to generic question stems with sample questions, access to model questions, two-way cyclic communication between authors of question and assessors, and the ability to conceal one’s real identity by anonymity or nickname, etc.), were confirmed to provide a high level of support. Recommendations for classroom implementations and future studies are offered.     

增量法在深基坑支护结构计算中的应用

通过应用增量法的原理，用ＳＡＰ８４程序对深基坑支护结构进行内力分析，说明增量法的使用方法和其科学性、合理性、安全性，并希望该法的应用能编入《深基坑支护技术规程（送审稿）》和进入相关的应用程序，以期该法能够在更大的范围内推广应用。