A correlation giving improved description of the capacity and efficiency of vane-type gas–liquid separators

Vane-type demisters are attractive droplet separators because they combine robustness and sufficient separation efficiency with a low-pressure drop, a high capacity and some fouling resistance. Experience shows that their optimal operation is close to the maximum capacity point and even that at this point the separation efficiency is better at higher pressures. This article proposes a generalized expression this point, as a function of gas and liquid flow and properties, drawing on knowledge about other, related, unit operations, namely cyclone separators and distillation towers. The generalized expression relates the dimensionless velocity with the Archimedes number and a flow parameter. The expression builds on earlier work on a criterion for the inception of droplet entrainment in two-phase film flow, pioneered by Ishii and Grolmes, and is supported by considerable experimental work published over the last 50 years.     

Team experiential cognitive style and team performance: The moderating impact of workplace setting

With an increasing need in organizations to come up with novel and useful ideas to renew and survive, team creativity has grown in importance to managers and researchers. As the cognitive resources of team members are the core input for team creativity, researchers increasingly look at team cognition in general and team cognitive styles in particular. In this research stream, the environmental context in which team members are embedded has received limited attention. We therefore experimentally test variation in the physical workplace environment and how it influences the relationship between team experiential cognitive styles and team creativity. Manipulating the nature of architectural elements in the room, we distinguish between a physical workplace with (i) experiential cues and (ii) rational cues. We also use a control condition where architectural elements are absent in the workplace environment. We rely on resource‐matching theory to build our hypotheses. Using data of 75 student teams of a Dutch university, we find that the relationship between teams' experiential cognitive style and team creativity was positive in the control condition. This positive relationship became insignificant in the two conditions where experiential or rational cues were introduced. Theoretical and practical implications are discussed.     

Electromagnetic modeling of high magnetic contrast media using Calderón preconditioning

In this contribution, we present a Calderón preconditioner for a novel single-source equation to efficiently model electromagnetic scattering problems involving high magnetic contrasts. Through analysis of the spectral properties of the system matrix after discretization, it is shown that this formulation does not break down when high permeabilities are present, which was an unresolved problem of the Calderón preconditioned Poggio–Miller–Chan–Harrington–Wu–Tsai method. The adopted discretization scheme, which involves Rao–Wilton–Glisson and Buffa–Christiansen basis functions, allows for an easy integration in existing commercial Method of Moments software. The efficiency and accuracy of the presented method is corroborated by numerical examples.     

Experimental study of the vortex end in centrifugal separators: The nature of the vortex end

The nature of the vortex end (or the “tail end” or “tip”) in reverse-flow centrifugal gas cleaning equipment, cyclones and swirl tubes, has been studied by visualization using a stroboscope and high-time-resolution pressure measurements. The core of the vortex is shown to bend to the wall of the separator, and rotate around the wall, forming the ring-shaped pattern normally observed at the vortex end. The end of the vortex was found to occur higher in the swirl tube (“less stable vortex”) when the solid loading is increased, and when the volumetric flow rate to the tube is decreased. The frequency with which the vortex core rotates varies with the gas flow rate and was found to be about the same as the frequency with which the gas rotates higher in the separator. The time-averaged wall pressure suddenly decreases in the separator body at the point where the vortex end attaches to the wall.     

An adaptive LTE listen-before-talk scheme towards a fair coexistence with Wi-Fi in unlicensed spectrum

The technological growth combined with the exponential increase of wireless traffic are pushing the wireless community to investigate solutions to maximally exploit the available spectrum. Among the proposed solutions, the operation of Long Term Evolution (LTE) in the unlicensed spectrum (LTE-U) has attracted significant attention. Recently, the 3rd Generation Partnership Project announced specifications that allow LTE to transmit in the unlicensed spectrum using a Listen Before Talk (LBT) procedure, respecting this way the regulator requirements worldwide. However, the proposed standards may cause coexistence issues between LTE and legacy Wi-Fi networks. In this article, it is discussed that a fair coexistence mechanism is needed to guarantee equal channel access opportunities for the co-located networks in a technology-agnostic way, taking into account potential traffic requirements. In order to enable harmonious coexistence and fair spectrum sharing among LTE-U and Wi-Fi, an adaptive LTE-U LBT scheme is presented. This scheme uses a variable LTE transmission opportunity (TXOP) followed by a variable muting period. This way, co-located Wi-Fi networks can exploit the muting period to gain access to the wireless medium. The scheme is studied and evaluated in different compelling scenarios using a simulation platform. The results show that by configuring the LTE-U with the appropriate TXOP and muting period values, the proposed scheme can significantly improve the coexistence among LTE-U and Wi-Fi in a fair manner. Finally, a preliminary algorithm is proposed on how the optimal configuration parameters can be selected towards harmonious and fair coexistence.     

Influence of microbial conversion and change in pH on iron–gallic acid complexation during lactobacillus fermentation

Plant products are rich in minerals, e.g. iron, as well as in phenolic acids, e.g. gallic acid (GA). GA contains a galloyl group leading to complexation with iron, and thus decreasing the bioavailability of iron. As complexation of GA–iron seems to be pH-dependent, lactic acid fermentation could be a technique to improve the bioavailability of iron. On the other hand different lactobacillus strains are able to metabolize GA into pyrogallol (PYR).     

Benefits of quantile regression for the analysis of customer lifetime value in a contractual setting: An application in financial services

The move towards a customer-centred approach to marketing, coupled with the increasing availability of customer transaction data, has led to an interest in understanding and estimating customer lifetime value (CLV). Several authors point out that, when evaluating customer profitability, profitable customers are rare compared to the unprofitable ones. In spite of this, most authors fail to recognize the implications of these skewed distributions on the performance of models they use. In this study, we propose analyzing CLV by means of quantile regression. In a financial services application, we show that this technique provides management more in-depth insights into the effects of the covariates that are missed with linear regression. Moreover, we show that in the common situation where interest is in a top-customer segment, quantile regression outperforms linear regression. The method also has the ability of constructing prediction intervals. Combining the CLV point estimate with the prediction intervals leads to a new segmentation scheme that is the first to account for uncertainty in the predictions. This segmentation is ideally suited for managing the portfolio of customers.     

Study of diesel fuel desulfurization by adsorption

Removal of sulfur from diesel fuel by adsorption on a commercial activated carbon and 13X type zeolite was studied in a batch adsorber. Kinetic characterization of the adsorption process was performed applying Lagergren's pseudo-first order, pseudo-second order and intraparticle diffusion models using data collected during experiments carried out to determine the sulfur adsorption dependency on time. The experiments investigating adsorption efficiency regarding initial sulfur concentration were also performed and the results were fitted to Langmuir and Freundlich isotherms, respectively. Activated carbon Norit SXRO PLUS was found to have much better adsorption characteristics. The process of sulfur adsorption on the fore mentioned activated carbon was further studied by statistically analyzing data collected during experiments which were carried out according to three-factor two-level factorial design. Statistical analysis involved the calculation of effects of individual parameters and their interactions on sulfur adsorption and the development of statistical models of the process.     

安特卫普:一座再创造和再度活跃的城市

安特卫普是比利时第二大城市,有着光辉的历史和可预期的未来.早在16世纪,它就是一座重要的城市、主要港口以及国际化的商业与文化中心,许多“佛兰德画派”的著名画家发现这是一个具有创意的空间和适合生活与创作的场所. 安特卫普的发展得益于其位于斯凯尔特河沿岸的优越地理位置:在狭长凹进的河流转弯处的最高点,右岸逐渐发展成天然的船只停泊处.在港口周边,渐渐发展出聚居地,并随着繁忙的港口活动发展成为一座世界级城市.     

Hand supports to assist toilet use among the elderly

Improving the toilet environment holds promises for increasing the quality of life for elderly and disabled persons. This is one of the goals of the Friendly Rest Room (FRR) project. The study described in this article explored the preference and use of supports in the toilet environment during the entire toilet ritual. An adjustable test frame was built with a toilet and three types of supports. Fourteen subjects were asked which positions they favoured for each support. After using all three supports, they were asked which support they found most comfortable. In general, the preferred positions depended on personal preferences more than on dimensions of the body. It was concluded that there is a preference for vertical supports for sitting down and standing up. During toilet use the side supports were equally appreciated.