Concept Of Layer Research Articles

Knowle: A semantic link network based system for organizing large scale online news events

An explosive growth in the volume, velocity, and variety of the data available on the Internet has been witnessed recently. The data originated from multiple types of sources including mobile devices, sensors, individual archives, social networks, Internet of Things, enterprises, cameras, software logs, health data has led to one of the most challenging research issues of the big data era. In this paper, Knowle—an online news management system upon semantic link network model is introduced. Knowle is a news event centrality data management system. The core elements of Knowle are news events on the Web, which are linked by their semantic relations. Knowle is a hierarchical data system, which has three different layers including the bottom layer (concepts), the middle layer (resources), and the top layer (events). The basic blocks of the Knowle system—news collection, resources representation, semantic relations mining, semantic linking news events are given. Knowle does not require data providers to follow semantic standards such as RDF or OWL, which is a semantics-rich self-organized network. It reflects various semantic relations of concepts, news, and events. Moreover, in the case study, Knowle is used for organizing and mining health news, which shows the potential on forming the basis of designing and developing big data analytics based innovation framework in the health domain.

Exit selection strategy in pedestrian evacuation simulation with multi-exits

A mixed strategy of the exit selection in a pedestrian evacuation simulation with multi-exits is constructed by fusing the distance-based and time-based strategies through a cognitive coefficient, in order to reduce the evacuation imbalance caused by the asymmetry of exits or pedestrian layout, to find a critical density to distinguish whether the strategy of exit selection takes effect or not, and to analyze the exit selection results with different cognitive coefficients. The strategy of exit selection is embedded in the computation of the shortest estimated distance in a dynamic parameter model, in which the concept of a jam area layer and the procedure of step-by-step expending are introduced. Simulation results indicate the characteristics of evacuation time gradually varying against cognitive coefficient and the effectiveness of reducing evacuation imbalance caused by the asymmetry of pedestrian or exit layout. It is found that there is a critical density to distinguish whether a pedestrian jam occurs in the evacuation and whether an exit selection strategy is in effect. It is also shown that the strategy of exit selection has no effect on the evacuation process in the no-effect phase with a low density, and that evacuation time and exit selection are dependent on the cognitive coefficient and pedestrian initial density in the in-effect phase with a high density.

Modelling a neural network using an algebraic method

In this paper, a framework based on algebraic structures to formalize various types of neural networks is presented. The working strategy is to break down neural networks into building blocks, relationships between each building block, and their operations. Building blocks are collections of primary components or neurons. In turn, neurons are collections of properties functioning as single entities, transforming an input into an output. We perceive a neuron as a function. Thus the flow of information in a neural network is a composition between functions. Moreover, we also define an abstract data structure called a layer which is a collection of entities which exist in the same time step. This layer concept allows the parallel computation of our model. There are two types of operation in our model; recalling operators and training operators. The recalling operators are operators that challenge the neural network with data. The training operators are operators that change parameters of neurons to fit with the data. This point of view means that all neural networks can be constructed or modelled using the same structures with different parameters.

Elucidating the oxide growth mechanism on platinum at the cathode in PEM fuel cells

Simulations of platinum oxidation in literature have yet to fully replicate an experimental cyclic voltammogram. In this manuscript a mechanism for platinum oxidation is proposed based upon the results of in operando X-ray absorption spectroscopy, where it was found that PtO2 is present at longer hold times. A new method to quantify extended X-ray absorption fine structure data is presented, and the extent of oxidation is directly compared to electrochemical data. This comparison indicated that PtO2 was formed at the expense of an initial oxide species. From previous literature studies it can be concluded that the rate of platinum oxidation is not a function of only potential and coverage. To that end, the concept of a heterogeneous oxide layer was introduced into the model, whereby place-exchanged PtO2 structures of varying energy states are formed through a single transition state. This treatment allowed, for the first time, the simulation of the correct current-potential behavior at varying scan rates and upper potential limits.

Boundary Layer of Photon Absorption Applied to Heterogeneous Photocatalytic Solar Flat Plate Reactor Design

This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA) were used as design parameters to determine (i) reactor thickness, (ii) maximum absorbed radiant energy, and (iii) the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA) inside the reactor was described using six-flux absorption-scattering model (SFM) applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.

Concept of Bed Roughness Boundary Layer and Its Application to Bed Load Transport in Flow with Non-Submerged Vegetation

Ecosystem conservation has become one of the purposes in river management as well as flood mitigation and water resources management, and understanding of river flow and morphology in a stream with vegetation becomes important. Recently 2D depth averaged analysis is familiar even in a stream with vegetation by taking account of form drag due to vegetation. However, the shear stress in vegetated area is not properly described because the resistance law due to bed roughness is not reasonably modified in vegetated area. In this study, we discussed the bed roughness boundary layer in flow with non-submerged vegetation to deduce a reasonable relation between U and u* in vegetated area toward improving the analysis of sediment transport. The results show that the modification of resistance law using by thickness, velocity distribution in that layer was found to bring significant improvement of accurate estimation of shear velocity and subsequently the sediment transport. The proposed modification is improved by 2D depth averaged analysis based on this concept, and its application is certificated through flume experiment.

Survey on Free Space Optical Communication: A Communication Theory Perspective

Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.

The Study of Residual Stresses in the Surface Layer

This essay synthetically presents a selection of technological properties of EN-GJS-500-7 Spheroidal cast iron castings and a selection of applications of spheroidal cast iron in the function of its chemical composition. The concept of the surface layer (SL) was defined, its classification and basic elements of its structure were provided. The essay presents the results of the Davidenkov's method research on internal stresses in the surface layer of the cast iron castings (in weld surfaced half products appropriated for preforms and glass moulds). The results of the research clearly show that the values of stresses occurring during weld surfacing depend on the thickness of the weld surfaced layer. Moreover, the research has determined an important influence of the thickness of this layer on the stresses in the base material (core).

Applications of electrokinetic phenomena in materials science

The discovery of electrokinetic phenomena by Reuss in 1808 and further investigations that gave rise to the concept of the electrical double layer have played an important role in the understanding of colloidal stability. Electrokinetic phenomena are a family of effects in which a liquid moves tangentially to a charged surface. Well-known phenomena of this kind are electrophoresis, electro-osmosis, streaming potential, and sedimentation potential. A review of parameters involved in the electrochemistry of suspensions is made. The practical applications of these phenomena have become widespread in a broad range of research fields such as biomaterials, biofilms, electrokinetic waste remediation, membranes, nuclear and fossil-fired power plants, adhesive and sealant science, and concrete science. The purpose of this paper is to provide an overview of electrokinetic phenomena and their application to surface modification and characterization in a large number of research fields such as corrosion and protection processes, environmental remediation (soil and sediments, transport processes, inorganic pollutants, solid particle surfaces, filter membranes, and biosorption phenomena), cement-based systems, and biological systems.

Design and Implementation of the Spatial Database for Reclaimed Water Utilization

In order to meet the application requirements of visual management and analysis of the information about recycled water use, the spatial database for the City Recycled Water Use is designed and constructed in this paper based on Geodatabase the spatial data model as well as UML and CASE as tools. The View Layer design, Concept design and Logic Design of the database of the recycled water use is explained in details. Then the application of the designed database to implement the Dianchi Lake Basin recycled water use in GIS platform is carried out and parts of the details is described in this paper.

Image Analysis Methods to Monitor Natura 2000 Habitats at Regional Scales – the MS. MONINA State Service Example in Schleswig-Holstein, Germany

Summary: The Natura 2000 network of protected sites is one of the means to address the issue of biodiversity conservation in Europe. Protected under the habitat directive, EU member states have to undertake surveillance of habitats and species of community interest and report every six years on habitat range and distribution, conservation status and the future prospects of the habitats within and outside of protected sites. Remote sensing techniques have been applied successfully to monitor habitat changes relevant for Natura 2000 monitoring using multioral satellite image data, but many challenges remain especially outside protected sites to assess the development of habitats over time. A flexible information layer concept was developed within the FP7 project MS.MONINA to address the complex task of monitoring natural habitats. In this paper the new approach to classify grassland land cover classes in Schleswig-Holstein, Germany, will be presented. Based on ecological parameters experts defined simple description models, which were used by image analysts to extract corresponding image features for four different grassland types. Information layer operators were defined to extract image features for subsequent classifications. (Less)

Development of structural carbon nanotube–based sensing composites for concrete structures

Structural health monitoring has become a viable solution to monitor critical infrastructure components that show distress or are unable to pass current load ratings. This research introduces the concept of a composite layer bonded to concrete structures, which is capable of providing distributed sensing capabilities. The layer consists of carbon nanotubes that are deposited on a carrier, which form a continuous conductive skin that is exceptionally sensitive to changes in strain and the formation and propagation of micro-damage and macro-damage. It can be either structural, where the layer represents the reinforcement as well as the sensor, or nonstructural, where the layer acts as a sensing skin alone. Distributed sensing allows for increased detectability of forming or growing damage that cannot necessarily be captured with conventional point-type sensors such as strain gages or accelerometers. Once developed, this sensing skin may be able to give real-time feedback on changes in strain, temperature effects, and formation and propagation of damage. In this article, we present the fabrication and evaluation of an integrated structural sensing composite layer attached to a concrete beam specimen. The specimen was tested to failure in the laboratory. Experimental results are presented and discussed, and currently ongoing research is introduced.

Discrete time second order sliding mode observer for uncertain linear multi-output system

This paper presents a second order sliding mode observer (SOSMO) design for discrete time uncertain linear multi-output system. The design procedure is effective for both matched and unmatched bounded uncertainties and/or disturbances. A second order sliding function and corresponding sliding manifold for discrete time system are defined similar to the lines of continuous time counterpart. A boundary layer concept is employed to avoid switching across the defined sliding manifold and the sliding trajectory is confined to a boundary layer once it converges to it. The condition for existence of convergent quasi-sliding mode (QSM) is derived. The observer estimation errors satisfying given stability conditions converge to an ultimate finite bound (within the specified boundary layer) with thickness O(T2) where T is the sampling period. A relation between sliding mode gain and boundary layer is established for the existence of second order discrete sliding motion. The design strategy is very simple to apply and is demonstrated for three examples with different class of disturbances (matched and unmatched) to show the effectiveness of the design. Simulation results to show the robustness with respect to the measurement noise are given for SOSMO and the performance is compared with pseudo-linear Kalman filter (PLKF).

Mathematical simulation of liquid extraction in a countercurrent multistage apparatus

A technique of calculating a multistage countercurrent liquid extraction in an apparatus with agitation of phases was proposed. Kinetic parameters of mass transfer was acquired based on concepts of pseudo-laminar boundary layer on the elements of the dispersed phase. An approximate method for calculating the installation was presented. The results of the calculation of the process according to a “stage by stage” scheme and approximate method are well consistent with each other.

Double-negative dynamic properties in one-dimensional multi-phase metamaterial based on the symmetrical equivalent layer

Acoustic metamaterials have important potential applications in engineering by their unusual properties. Based on the concept of symmetrical equivalent layer, it is found that layered acoustic metamaterial which exhibits simultaneously negative effective modulus and density can be existed. By using the transfer matrix method, the continuous double-negative dynamic properties can be achieved through a multi-phase microstructure considering viscous damping, and the left-handed wave propagation property appears during the double-negative frequency regions. This will be a reference for the design of 1D acoustic negative refraction metamaterials.

A balanced water layer concept for subglacial hydrology in large-scale ice sheet models

Abstract. There is currently no doubt about the existence of a widespread hydrological network under the Antarctic Ice Sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux–basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

ID Layer for Internet of Things Based on Name-Oriented Networking

Object and service identification is considered as one of the main challenges in the field of Internet of Things (IoT), which can be solved by the introduction of the so called ID (IDentifier) layer. The objective of this layer is to expose IoT objects and services offered by them, to users. Common approach for ID layer is to create it in overlay manner, on the top of existing network. This paper presents a novel architecture of the ID layer, which is characterized by embedding ID layer functionality into the network plane. Moreover, this approach takes advantage of the Name-Oriented Networking (NON) paradigm. To gain easy access to the IoT objects and services, as well as native support for multicast service, human readable ID-based unified addressing with hierarchical structure was exploited. Additionally, in-network caching of forwarded IoT data, inherited from the NON, helps to reduce total network load and supports applications during collaboration with energy-constrained sensors. Such sensors may enter sleep mode to save energy and then the network nodes can serve requests for sensing data, arrived from applications, by using data stored in nodes’ cache. The paper shows the concept of NON-based ID layer and describes functional architecture of network node paying attention on modules and mechanisms related with ID layer functionality. Primary ID layer processes, i.e., object/service registration, resolution and data forwarding are explained in detail. Moreover, the ID-aware network node was implemented on Linux-based platform and tested to check its forwarding characteristics. The tests showed the performance of the of ID network node in data plane operations, which are the more sensitive for scalability issues.

A semi-analytical model of the 3D boundary layer over the streamlined nose of a train

The boundary layer concept is applied to the flow around the nose of a streamlined train. In general, that flow is not axisymmetric due to the shape of the nose and the crosswind component of the relative incoming velocity. This departure from axisymmetry produces a transverse pressure gradient that is responsible for skewing an otherwise plane boundary layer. An empirical correlation, dependent on the longitudinal velocity and one unknown parameter, is used to represent the transverse velocity profile. The value of that unknown parameter is obtained from the momentum equations integrated streamwise inside the boundary layer. A visual comparison was carried out between the numerical simulations and the skin shear pattern of a scale model in a wind tunnel. The qualitative results compare well, the numerical model being able to locate the position of the main longitudinal vortices on the lee side of the train.

Polycrystalline silicon thin-film solar cells: Status and perspectives

The present article gives a summary of recent technological and scientific developments in the field of polycrystalline silicon (poly-Si) thin-film solar cells on foreign substrates. Cost-effective fabrication methods and cheap substrate materials make poly-Si thin-film solar cells promising candidates for photovoltaics. However, it is still the challenge for research and development to achieve the necessary high electrical material quality known from crystalline Si wafers on glass as a prerequisite to harvest the advantages of thin-film technologies. A wide variety of poly-Si thin-film solar cell approaches has been investigated in the past years, such as thermal solid phase crystallization – the only technology that had already been matured to industrial production so far – the seed layer concept where a large-grained seed layer is epitaxially thickened, direct growth of fine grained material, and liquid phase crystallization methods by laser or electron beam. In the first part of this paper, the status of these four different poly-Si thin-film solar cell concepts is summarized, by comparing the technological fabrication methods, as well as the structural and electrical properties and solar cell performances of the respective materials. In the second part, three promising technologies are described in more detail due to their highly auspicious properties regarding material quality and throughput aspects during fabrication: (1) High-rate electron–beam evaporation of silicon for the low-cost deposition of high-quality material, (2) large-area periodic nano- and micro-structuring of poly-Si by the use of imprinted substrates providing a large absorption enhancement by a factor of six at a wavelength of 900nm, (3) liquid-phase crystallization of silicon thin-film solar cells by electron–beam, yielding an excellent poly-Si material quality reflected by an open-circuit voltage of 582mV which has been achieved only very recently. A successful combination of these three complementary technologies is envisaged to be the basis for a prospective low-cost and highly efficient poly-Si solar cell device.

Robust consensus tracking of multi‐agent systems with uncertain Lur'e‐type non‐linear dynamics

This study addresses the robust consensus tracking problem of multi-agent systems with uncertain Lur'e-type non-linear dynamics under a fixed topology. To achieve consensus tracking, a class of discontinuous control protocols are first proposed, which rely on the relative information among the neighbouring agents. Theoretical analysis indicates that the robust consensus tracking of uncertain Lur'e network can be achieved if the coupling strength and the control gain are both larger than the thresholds depending on some global information of the network. Then, an adaptive consensus tracking protocol is further designed to solve the robust consensus tracking problem as a modification of a fully distributed version without the need of any global information of the multi-agent systems. Furthermore, as an expansion of the discontinuous protocols, a new class of continuous control laws are developed based on the boundary layer concept. Finally, a couple of examples are given to illustrate the effectiveness of the theoretical results.