The simulation of hydrolytic polymerization of ε-caprolactam in various reactors: A simulation model for the tubular reactor with heat exchanger and its numerical solution

A concrete simulation model which deals with the hydrolytic polymerization of ε-caprolactam (CL) in the tubular reactor (TR) with the heat exchangers (HEx's) was described, and a method for its numerical solution was presented. The numerical calculations were carried out for 13 cases, where the position and number of the HEx's in the TR were varied. The effects of the HEx on the distribution of the temperature in the TR and of the characteristic data of the polymerization (the concentration of CL and number average degree of polymerization) in the TR and at the outlet of the TR were investigated. The results suggested that the HEx positioned at the upper half of the TR and the HEx positioned at the lower half of the TR are effective to narrow the temperature distribution in the TR and to produce the polymer product with narrower molecular weight distribution, respectively.     

A quorum-based protocol for searching objects in peer-to-peer networks

Peer-to-peer (P2P) system is an overlay network of peer computers without centralized servers, and many applications have been developed for such networks such as file sharing systems. Because a set of peers dynamically changes, design and verification of efficient protocols is a challenging task. In this paper, we consider an object searching problem under a resource model such that there are some replicas in a system and the lower bound of the ratio /spl rho/=n'/n is known in advance, where n' is a lower bound of the number of peers that hold original or replica for any object type and n is the total number of peers. In addition, we consider object searching with probabilistic success, i.e., for each object search, object must be found with at least probability 0相似文献   

Prevention of story drift amplification in a 20‐story steel frame structure by tension‐rod displacement–restraint bracing

This paper proposes an application of tension‐rod displacement–restraint bracing to prevent story drift amplification in tall steel moment frames. Seismic response analyses of a 20‐story bare steel frame are performed first, revealing that story drift amplification occurs in the upper and lower stories at different times. Characteristics observed for the seismic response of the bare frame suggest the efficacy of the delay action of bracing. Subsequently, seismic response analyses of the 20‐story braced frame with tension‐rod displacement–restraint bracings reveals that the increment of the column axial force by addition of bracing is reduced dramatically by the delay action of bracing. The story rotation angles within partial stories where the story drift amplification occurs in the bare frame are also reduced efficiently by the displacement–restraint bracing. The delay action of bracing influences the floor response acceleration and the residual displacement. Finally, parametric analysis results indicate an appropriate value of the story rotation angle at which the brace action starts.     

Three-dimensional numerical computation for magnetic convection of air inside a cylinder heated and cooled isothermally from a side wall

Three-dimensional convection of air in a vertical cylinder isothermally heated and cooled from a side wall was numerically computed both in magnetic and gravity fields. A single electric coil was placed around a cylinder to generate a magnetic field. Convection was calculated for various coil levels and magnetic strengths. The gravity field, magnetic strength and Rayleigh number are shown to have substantial effect. Convection modes and heat transfer rates are also presented.     

地震作用下钢结构的破坏及抗震性能的提高

首先探讨了地震对现代钢结构建筑的破坏情况,主要介绍了1995年兵库县南部地震的震害情况。研究了地震作用对梁柱节点、柱、梁、支撑以及柱脚的破坏。对非结构构件在地震作用下的破坏以及结构对长周期地震的响应进行了研究。其次,列出了钢结构抗震性能提高和抗震评估的方法。对改进的梁柱节点形式,例如改进扇形开孔形状和减小梁截面等进行了研究并建议在实际工程中采用。介绍并探讨了约束屈曲支撑和阻尼器的应用。最后,列出了对既有钢结构建筑抗震性能的评估方法。     

Analytical method of cereulide in processed cereal-based foods and milk powder by LC-MS/MS

An LC-MS/MS method for analysis of cereulide, an emetic toxin produced by Bacillus cereus, was developed. Cereulide was extracted from samples, fried rice, pan-fried noodles, red bean paste and baby formula, with methanol and purified using Oasis HLB cartridges. LC separation was performed on a C18 column with a mixture of formic acid solution and methanol containing ammonium formate as a mobile phase, and the mass spectrometer was operated in the positive electrospray ionization mode. Performance evaluation showed that trueness was higher than 70% and repeatability and reproducibility were within 10%. The limits of quantification were lower than 1 μg/kg.     

The effect of lubricants on deep drawability of zinc-coated steel sheets

The effect of lubricants on deep drawability was studied for two types of zinc-coated steel sheets on a high-speed deep-drawing machine. The drawability of galvannealed steel sheet, GA, at low speeds is significantly improved by friction modifiers, due to reduction in frictional forces around the die radius. In contrast to the results for GA, double layered steel, GAE, which has an Fe-rich alloy coating on the top, and is superior to GA in terms of drawability, is insensitive to changes in the additives. This is mainly because the hardness of the upper coating layer of GAE decreases frictional resistance through a decline in the boundary contact area.     

Control of head smear generation by diamond-like carbon films using an external electric field

Microsystem Technologies - The formation of head smears in heat-assisted magnetic recording is a significant problem that must be addressed to ensure the reliability of the head-disk interface. In...