Proposed design methods for lateral torsional buckling of unrestrained steel beams in fire

The behaviour of unrestrained steel I-beams has been studied by means of numerical analysis and published experimental results. The numerical model was developed using a commercial finite element program, MSC.MARC Mentat. A series of different UB and UC sections and different spans, subjected to both uniform moment and midspan point loads, are considered. The numerical predictions of the buckling moments are then compared with published experimental results. Consequently, a new approach is proposed to provide more accurate and safe predictions of the fire resistance of unrestrained beams, as well as to overcome certain weaknesses in the EC3:1.2 [European committee for standardization (CEN). Eurocode 3: Design of steel structures, Part 1.2: General rules — structural fire design, EN 1993-1-2. Brussels (Belgium); 2005] design formula. In addition, to provide a quick and simple design approach for engineers, a straightforward and rational method known as the Rankine method is introduced to predict the LTB failure load of steel beams in fire. It is shown that the Rankine approach generally provides a good lower bound value for numerical predictions.     

火灾中无约束钢梁的扭转弯曲的设计方法

采用数字分析和相关试验结果研究了无约束钢I截面梁的行为,采用有限元程序拓展了数学模型。在相同弯矩和中跨集中荷载的情况下,对一系列不同的UB和UC截面以及不同跨度,进行了研究。比较了预估的弯矩值与相关试验结果。在此基础上,对无约束梁提出了一种新的更精确和安全防火预报的方法,该方法克服了欧洲规范（EC3：1．2）设计公式中的一些弱点。另外,给设计者提供了一个便捷和简单的设计方法,即该方法易懂又合理,称为兰金方法。可用于预估钢梁在火中的LTB破坏荷载。兰金方法为数值预估提供了一个适宜的下界值。     

Clinical evaluation of carbon-11-phenylephrine: MAO-sensitive marker of cardiac sympathetic neurons

The sympathomimetic drug phenylephrine recently has been labeled with 11C for use in PET studies of cardiac sympathetic innervation. Previous reports using isolated perfused rat heart models indicate that phenylephrine is metabolized by intraneuronal monoamine oxidase (MAO). This report compares the imaging characteristics, neuronal selectivity and kinetics of (-)-[11C]phenylephrine (PHEN) to the structurally similar but MAO-resistant analog (-)-[11C]-meta-hydroxyephedrine (HED), an established heart neuronal marker. METHODS: Fourteen healthy volunteers were studied with PET and PHEN. Ten had paired studies with HED; four of the 10 were scanned a second time with each tracer after oral administration of desipramine, a selective neuronal transport blocker. Hemodynamic and electrocardiographic responses were monitored. Blood levels of intact radiotracer and radiolabeled metabolites were determined from venous blood samples taken during the PET study. Myocardial retention indices for both tracers were calculated. RESULTS: No hemodynamic or electrocardiographic effects were observed with either tracer. PHEN showed reduced myocardial retention at 50 min compared to HED; however, image quality and uniformity of distribution were comparable. PHEN cleared from myocardium with a mean half-time of 59 +/- 5 min, while myocardial levels of HED remained constant. PHEN metabolites appeared in the blood approximately three times faster than HED metabolites. Desipramine pretreatment markedly reduced (> 60%) myocardial retention of both PHEN and HED. CONCLUSION: PHEN provides PET images of human heart comparable in quality and uniformity to HED. Like HED, PHEN localizes in the sympathetic nerves of the heart. However, the more rapid efflux of PHEN, that is likely mediated by MAO, may provide information on the functional status of cardiac sympathetic neurons unobtainable with HED.     

A new three-terminal switching device

A new switching device has been conceived and reduced to practice. This device is a once-programmable three-terminal fuse (TTF) with an on-resistance of a good metallic conductor and an off-resistance which is essentially infinite. In the new structure the fusible circuit path is fully isolated from a control electrode both before and after programming. We discuss the basic concept of the TTF and highlight some of its possible applications     

Simulation and Prediction of Methyl‐mercaptan Removal by Chemical Scrubbing with Hydrogen Peroxide

A model has been developed in order to predict the behavior of methylmercaptan chemical scrubbing using hydrogen peroxide. New constants concerning reactions involving methylmercaptan have been proposed based on mass transfer and kinetic equations for the dissociation of methylmercaptan by the hydroxide and the reaction with perhydroxyl ions. Once this step has been achieved, the model is used to characterize the influences of the different chemical scrubbing operating parameters, i.e., the gas‐liquid contact time, the oxidant concentration, and the pH. As expected, an increase in the hydrogen peroxide concentration, the contact time, or the pH leads to an increase in the methylmercaptan removal level. However, the most interesting aspect of the model lies in the possibility of defining a new or limiting value for each parameter, below which the process is not efficient enough to be industrially implemented.     

CHANGING DEMOGRAHICS AND LIFE STYLES: What Are Recent Homebuyers Really Like?

ABSTRACT: Cross-tabular and cluster analysis are applied to mailed questionnaire samples for Hamilton County (Cincinnati), Ohio, and New Castle County (Wilmington), Delaware, to determine the extent to which recent demographic and life style trends associated with neighborhood revitalization influenced the composition of the homebuying population. In fact, these trends have had only a limited impact. Although Hamilton County contained a homebuyer cluster of upwardly mobile singles and couples without children, neither county had a homebuyer cluster identifiably based on both demographic and attitudinal characteristics. Further, suburban rather than urban values dominated the homebuying populations in these counties. The fact that Hamilton County contains a more cosmopolitan-like cluster than New Castle County highlights the fact that some cities have brighter prospects than others for attracting additional middle income families.     

Recent applications of particle image velocimetry in aerodynamic research

Particle image velocimetry (PIV) is increasingly used to investigate unsteady velocity fields instantaneously. For the first time the PIV technique allows the recording of a complete velocity field in a plane of the flow within a few microseconds. The PIV technique thereby provides information about unsteady flow fields which is difficult to obtain with other experimental techniques. The short acquisition times and fast availability of data reduce the operational time, and hence cost, in large scale wind tunnels and test facilities.

At DLR a variety of PIV systems for use in industrial wind tunnels has been developed in the past decade. The flexibility of these portable systems is illustrated by presenting several results of recent PIV applications. More recently the original photographic means of PIV image recording has been partially replaced by high resolution electronic imaging which can provide PIV data nearly on-line. Images recorded by either system use the same multiple-pass, cross-correlation analysis software, whose algorithms are briefly described. Several examples of actual applications are given: the flow issuing from a jet nozzle was imaged by a specially developed high-speed video camera at close proximity. A high resolution dual-frame digital camera was applied in the study of helicopter rotor aerodynamics and wake vortex measurements of an airplane model. Further, large image sequences exceeding 100 PIV recordings provided detailed information on the structure of a turbulent boundary layer.     

A Novel Video Coding Framework with Tensor Representation for Efficient Video Streaming

Video compression is one among the pre-processes in video streaming. While capturing moving objects with moving cameras, more amount of redundant data is recorded along with dynamic change. In this paper, this change is identified using various geometric transformations. To register all these dynamic relations with minimal storage, tensor representation is used. The amount of similarity between the frames is measured using canonical correlation analysis (CCA). The key frames are identified by comparing the canonical auto-correlation analysis score of the candidate key frame with CCA score of other frames. In this method, coded video is represented using tensor which consists of intra-coded key frame, a vector of P frame identifiers, transformation of each variable sized block and information fusion that has three levels of abstractions: measurements, characteristics and decisions that combine all these factors into a single entity. Each dimension can have variable sizes which facilitates storing all characteristics without missing any information. In this paper, the proposed video compression method is applied to under-water videos that have more redundancy as both the camera and the underwater species are in motion. This method is compared with H.264, H.265 and some recent compression methods. Metrics like Peak Signal to Noise Ratio and compression ratio for various bit rates are used to evaluate the performance. From the results obtained, it is obvious that the proposed method performs compression with a high compression ratio, and the loss is comparatively less.