Shape-Resonant Superconductivity in Nanofilms: from Weak to Strong Coupling

Ultrathin superconductors of different materials are becoming a powerful platform to find mechanisms for enhancement of superconductivity, exploiting shape resonances in different superconducting properties. Here, we evaluate the superconducting gap and its spatial profile, the multiple gap components, and the chemical potential, of generic superconducting nanofilms, considering the pairing attraction and its energy scale as tunable parameters, from weak to strong coupling, at fixed electron density. Superconducting properties are evaluated at mean field level as a function of the thickness of the nanofilm, in order to characterize the shape resonances in the superconducting gap. We find that the most pronounced shape resonances are generated for weakly coupled superconductors, while approaching the strong coupling regime the shape resonances are rounded by a mixing of the subbands due to the large energy gaps extending over large energy scales. Finally, we find that the spatial profile, transverse to the nanofilm, of the superconducting gap acquires a flat behavior in the shape resonance region, indicating that a robust and uniform multigap superconducting state can arise at resonance.     

A probabilistic model for correcting the directional sensitivity of optical probe measurements

A probabilistic model is introduced for correcting the directional sensitivity of the optical probe technique routinely used to determine gas holdup and bubble dynamics in gas‐liquid systems. Measurements from optical probes oriented at various angles were collected from the tapered end of optical probes in regions where approximately unidirectional and bubbly flow conditions were observed. Based on logical assumptions, constitutive equations for a probabilistic model were formulated, and contributions to the overall local gas phase holdup from bubbles traveling in two opposite directions were quantified. The results demonstrate a novel and useful way to interpret optical probe measurements. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3516–3527, 2015     

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琼东南盆地是南海北部大陆架新生代北东向伸展盆地,面积约３．４×１０４ｋｍ２,最大沉积厚度１２０００ｍ。盆内存在８个凹陷,依据凹陷的烃源层发育特征、埋藏史、生烃史、生烃强度及资源量综合分析,发现崖南、松南、宝岛、乐东和陵水凹陷均存在高温高压、烃源岩热演化程度高、生气强度大且资源量丰富,因此评价为富气凹陷;油气主要生成于下第三系,８个凹陷中以宝岛,松南凹陷成熟面积最大,两凹陷资源量约占下第三系气资源量的一半以上;松东凹陷因其热演化程度适中,油资源量占较大比例,该凹陷油、气均具有勘探潜力,而崖北及松西凹陷生烃潜力较差。为此,围绕上述富气（烃）凹陷评价并综合天然气的成藏条件,初步筛选琼西基底披覆背斜带、松涛凸起及北东倾没端圈闭带、２号断裂下降盘圈闭带是最具天然气勘探潜力区带,而松东凹陷北坡圈闭带则为油气并举的勘探有利区带。     

Deposition of silver ions onto DBD and DCSBD plasma treated nonwoven polypropylene

The aim of this work is plasma activation of nonwoven polypropylene (PP) using two different ambient air plasma sources: volume dielectric barrier discharge (DBD) and diffuse coplanar surface barrier discharge (DCSBD) and its functionalization by silver ion deposition.     

CFD modeling of multiphase flow distribution in catalytic packed bed reactors: scale down issues

Flow maldistribution in either a bench-scale or commercial scale packed bed is often responsible for the failure of the scale down unit to mimic the performance of the large reactor. The modeling of multiphase flow in a bench-scale unit is needed for proper interpretation of reaction rate data obtained in such units. Understanding the mechanism of flow maldistribution is the first step to avoiding it. In order to achieve this objective, computational fluid dynamic (CFD) simulations of multiphase flow under steady state and unsteady state conditions in bench-scale cylindrical and rectangular packed beds are presented for the first time. The porosity distribution in packed beds is implemented into CFD simulation by pseudo-randomly assigned cell porosity values within certain constraints. The flow simulation results provide valuable information on velocity, pressure, and phase holdup distribution.     

Identification of defect-prone classes in telecommunication software systems using design metrics

The goal of this paper is to investigate the relation between object-oriented design choices and defects in software systems, with focus on a real-time telecommunication domain. The design choices are measured using the widely accepted metrics suite proposed by Chidamber and Kemerer for object oriented languages [S.R. Chidamber, C.F. Kemerer, A metrics suite for object oriented design, IEEE Transactions on Software Engineering 20 (6) (1994) 476-493].This paper reports the results of an extensive case study, which strongly reinforces earlier, mainly anecdotal, evidence that design aspects related to communication between classes can be used as indicators of the most defect-prone classes.Statistical models applicable for the non-normally distributed count data are used, such as Poisson regression, negative binomial regression, and zero-inflated negative binomial regression. The performances of the models are assessed using correlations, dispersion coefficients and Alberg diagrams.The zero-inflated negative binomial regression model based on response for a class shows the best overall ability to describe the variability of the number of defects in classes.     

Benchmarking distribution centres using Principal Component Analysis and Data Envelopment Analysis: A case study of Serbia

The efficiency of distribution systems is largely affected by the performances of distribution centres. The main objective of this paper is to develop and propose a DEA model for distribution centres efficiency measuring that can help managers in decision making and improving the efficiency. Due to numerous indicators that describe DCs operating, the main problem is indicators selection. In order to improve discriminatory power of classical DEA models PCA–DEA approach is used. This paper analysis the efficiency of distribution centres of one trading company in Serbia. Proposed models integrate operational, quality, energy, utilisation and equipment warehouse and transport indicators. Several hypotheses are tested in this paper. The results showed that small distribution centres are more efficient than large.     

Variable neighborhood search algorithm for heterogeneous traveling repairmen problem with time windows

The focus of this paper is generalized traveling repairman problem (TRP), a special case of the well known and well studied traveling salesman problem (TSP). Because of its specific objective function, that minimizes the sum of overall time all clients wait for until the end of a service, TRP has great applicability potential in client oriented practical problems. Therefore it has been known in literature as traveling deliveryman problem, minimum latency problem and cumulative capacitated vehicle routing problem. However, most studies that have treated TRP related problems have implied that only one repairman is present in the system and/or that all clients are available for service at the beginning of the planning horizon. In this paper we consider a TRP with a heterogeneous fleet of repairmen serving a set of clients whose arrival times are distributed over a planning horizon, i.e. heterogeneous TRPTW (hetTRPTW). For the hetTRPTW we present a mixed integer linear programming model, and a heuristic algorithm based on a variable neighborhood search (VNS) framework. Additionally, we propose a reduction strategy for neighborhoods in the VNS algorithm and test efficiency of implemented algorithms on four benchmark sets of problem instances. Results show that proposed algorithms could be used in real systems for solving small and moderate problem instances.