Basic Configurations Research Articles

Basic Experimental Characterization of Polymer Matrix Composite Materials

Composite materials are used in high-performance applications where achieving low weight is of concern. Since their introduction in the early 1960s, composite materials consisting of strong fibers in a polymer matrix have received considerable success. Because of the great variety of fiber and matrix combinations, there is no general data base of material properties available for the designer of composite structures. Design of composite materials demands accurate experimental determination of the mechanical properties of the composite materials considered. The emphasis of this article is on the experimental characterization of composite materials in the most basic loading configurations, viz. tension, compression, and shear. The description of the test methods is limited to in-plane mechanical response, with the exception of short-beam shear testing.

Formation of Coronal Shock Waves

Numerical simulations of magnetosonic wave formation driven by an expanding cylindrical piston are performed to get better physical insight into the initiation and evolution of large-scale coronal waves. Several very basic initial configurations are employed to analyze intrinsic characteristics of the MHD wave formation that do not depend on specific properties of the environment. It turns out that these simple initial configurations result in piston/wave morphologies and kinematics that reproduce common characteristics of coronal waves. In the initial stage the wave and the expanding source-region cannot be clearly resolved. During the acceleration stage of the source-region inflation, the wave is driven by the piston expansion, so its amplitude and phase-speed increase, whereas the wavefront profile steepens. At a given point, a discontinuity forms in the wavefront profile. The time/distance required for the shock formation is shorter for a more impulsive source-region expansion. After the piston stops, the wave amplitude and phase-speed start decreasing. During the expansion, most of the source region becomes strongly rarified, which reproduces the coronal dimming left behind the eruption. On the other hand, the density increases at the source-region boundary, and stays enhanced even after the expansion stops, which might explain stationary brightenings that are sometimes observed at the edges of the erupted coronal structure. In addition, in the rear of the wave a weak density depletion develops, trailing the wave, which is sometimes observed as weak transient coronal dimming. Finally, we find a well defined relationship between the impulsiveness of the source-region expansion and the wave amplitude and phase speed. The results for the cylindrical piston are also compared with the outcome for a planar wave, to find out how different geometries affect the evolution of the wave.

Generalised analytical methods and current‐energy control design for modular multilevel cascade converter

Modular multilevel cascade converter (MMCC) is a family of the emerging multilevel converters that are configured with a cascaded connection of full-bridge submodules or half-bridge ones by distinct topological structures. So far, MMCC family can be classified by basic configurations and submodule types into single-star full-bridge, double-star half-bridge (modular multilevel converter (MMC)), double-star full-bridge, double-star half-bridge back-to-back (indirect MMC), triple-star full-bridge (modular multilevel matrix converter, M3C), single-delta full-bridge and double-delta full-bridge (Hexverter). This study introduces a generalised and standard analytical procedure for MMCC and deals with the double-star half-bridge case (MMC) as example. A particular defined circulating current with a clearer physical meaning is used to analyse the complicated branch current composition and branch energy fluctuation. A full mathematical model based on state-space equations is established for MMC and a corresponding energy-current control strategy is presented. The validity of the control design and effectiveness of MMC is confirmed by simulation and experiment.

FLUTTER SUPPRESSION OF AN ELASTICALLY SUPPORTED PLATE WITH ELECTRO-RHEOLOGICAL FLUID CORE UNDER YAWED SUPERSONIC FLOWS

This paper investigates the active control of the supersonic flutter motion of an elastically supported rectangular sandwich plate, which has a tunable electrorheological (ER) fluid core and rests on a Winkler–Pasternak elastic foundation, subjected to an arbitrary flow of various yaw angles. The classical thin plate theory is adopted. The ER fluid core is modeled as a first order Kelvin–Voigt material, and the quasi-steady first order supersonic piston theory is employed for the aerodynamic loading. The generalized Fourier expansions in conjunction with Galerkin method are employed to formulate the governing equations in the state-space domain. The critical dynamic pressures at which unstable panel oscillations occur are obtained for a square sandwich plate, with or without an interacting soft/stiff elastic foundation, for selected applied electric field strengths and flow yaw angles. The Runge–Kutta method is then used to calculate the open-loop aeroelastic response of the system in various basic loading configurations. Subsequently, a sliding mode control (SMC) synthesis is set up to actively suppress the closed loop system response in yawed supersonic flight conditions with imposed excitations. The results demonstrate the performance, effectiveness, and insensitivity with respect to the spillover of the proposed SMC-based control system.

Analysis of a variable speed vapor compression system using artificial neural networks

An artificial neural network (ANN) is a mathematical model that is inspired by the operation of biological neural networks. However, this is typically considered a computational model. An ANN can easily adapt to multiple situations and extract information that is apparently hidden in a system.An ANN can be used in three basic configurations: mapping, auto-association and classification. An ANN in a mapping configuration can be used to model a two port system with inputs and outputs. Therefore, a vapor compression system can be modeled using an ANN in a mapping configuration. That is, some parameters from the compression system can be used for input while other parameters can be used as output. The simulation experiments include the design, training and validation of a set of ANNs to find the best architecture while minimizing over-fitting.This paper presents a new method to model a variable speed vapor compression system. This method accurately estimates the number of neurons in the hidden layer of an ANN. The analysis and the experimental results provide new insights to understand the dependency between the input and output parameters in a vapor compression system, concluding that the model can predict the energetic performance of a variable speed vapor compression system. Additionally, the simulation results indicate that an ANN can extract, from the data sets, information that is implicit in the configuration of the vapor compression system.

Modified Method for Reliability Evaluation of Condensation Thermal Electric Power Plant

Present methods for forecasting and evaluation of thermal power plants reliability were based on appliance of statistics and probability calcu lation related to strength and in the same time lean ing on modern methods for deterministic project-constructive calculations of elements, subsystems and systems. Applying the advantages of modern directions in system reengineering and structural or RCM (Reliability Centered Maintenance) way of using the best methods in reliability analysis of complex systems, the block diagram of mod ified method for basis referential 300 MW block has been created. As a starting database, the results of research of basic configurations of thermal power p lants for solid fuel Ug ljev ik and Gacko with nominal referential power of 300 MW were used. For other facilities inside thermal power p lants witch no minal power differs fro m 300 MW, recalcu lation of reliability indicators has to be carried out. Whereat the simple emp irical relation in dependence of previously determined reliability indicator for 300 MW system is used so as the exponent determined on basis of statistical data processing from the exp loitation during the lifespan of the power plant. The method is of the iterative nature and is about to be terminated as the starting hypothesis related to matching of results of the forecasting and real exploitation results affirms. The research related for suggested modified method gave several relat ively new results which are presented inside the paper. The result represents the algorithm of modified method for evaluation of reliability of referential thermal power plant system and its modificat ion aiming to include thermal power plants of other nominal powers.

As configurações genéricas e multimodais do videoclipe

Apesar da sua crescente circulação social e popularização nos meios de comunicação de massa (televisão, internet e variados dispositivos eletrônicos móveis, tais como tablets e celulares), o gênero videoclipe ainda não tem recebido a devida atenção das pesquisas linguísticas e discursivas. Norteado pelo intuito de sanar essa omissão e buscando adotar uma abordagem multidisciplinar para esse objeto, este trabalho lança mão de pressupostos da sociorretórica e dos estudos da multimodalidade textual com o propósito de estabelecer uma categorização das configurações genéricas dos clipes. Para tanto, utiliza-se como critério a saliência dos atributos observados na sua organização composicional, estilo, conteúdo temático e na sua dinâmica. Com isso, esta investigação procura empregar um parâmetro único, coerente e suficientemente amplo, aprimorando as classificações atuais, bastante inconsistentes e/ou demasiado rebuscadas. Outro diferencial da presente proposta tipológica consiste em associar a cada configuração uma potencial autoimagem construída pelo/a cantor/a no vídeo musical – algo que, até o momento, ainda não havia sido contemplado de forma sistemática pelos demais pesquisadores da área. Para o corpus analítico, foram selecionados os seguintes videoclipes da cantora norte-americana Madonna: Material girl (1985), Vogue – MTV’s 1990 Music Video Awards (1990), Bedtime story (1995) e Hollywood (2003). Como resultado da análise, é possível propor as seguintes configurações genéricas básicas para o estudo dos clipes: a) videoclipes com saliência na performatividade; b) videoclipes com saliência na ficcionalidade; e c) videoclipes com saliência na artisticidade.

Mechanics of rolling of nanoribbon on tube and sphere

The configuration of graphene nano-ribbon (GNR) assembly on carbon nanotube (CNT) and sphere is studied through theoretical modeling and molecular simulation. The GNR can spontaneously wind onto the CNT due to van der Waals (vdW) interaction and form two basic configurations: helix and scroll. The final configuration arises from the competition among three energy terms: the bending energy of the GNR, the vdW interaction between GNR and CNT, the vdW between the GNR itself. We derive analytical solutions by accounting for the three energy parts, with which we draw phase diagrams and predict the final configuration (helix or scroll) based on the selected parameters. The molecular simulations are conducted to verify the model with the results agree well with the model predicted. Our work can be used to actively control and transfer the tube-like nanoparticles and viruses as well as to assemble ribbon-like nanomaterials.

Virtual Table-Teleporter: Image Processing and Rendering for Horizontal Stereoscopic Display

We describe a new architecture composed of software and hardware for displaying stereoscopic images over a horizontal surface. It works as a ``Virtual Table and Teleporter'', in the sense that virtual objects depicted over a table have the appearance of real objects. This system can be used for visualization and interaction. We propose two basic configurations: the Virtual Table, consisting of a single display surface, and the Virtual Teleporter, consisting of a pair of tables for image capture and display. The Virtual Table displays either 3D computer generated images or previously captured stereoscopic video and can be used for interactive applications. The Virtual Teleporter captures and transmits stereoscopic video from one table to the other and can be used for telepresence applications. In both configurations the images are properly deformed and displayed for horizontal 3D stereo. In the Virtual Teleporter two cameras are pointed to the first table, capturing a stereoscopic image pair. These images are shown on the second table that is, in fact, a stereoscopic display positioned horizontally. Many applications can benefit from this technology such as virtual reality, games, teleconferencing, and distance learning. We present some interactive applications that we developed using this architecture.

Basic combinatorial configurations in preschool teacher education

The paper presents arguments for the need for combinatorial education of preschool teachers. To this effect, the author presents the minimal content which such training should cover in his opinion. Through examples related to practical situations, the author seeks to bring this matter closer to the readers who have had difficulties concerning mathematics during school.

On Contact Resistance of Carbon Nanotubes

Carbon nanotubes (CNTs) have found many potential applications stemming from their small dimensions and marvellous electronic, mechanical, and thermal properties. One of the barriers for using CNTs as building blocks in nanoelectronics is the high contact resistance. This paper reviews recent progress on the research of contact resistance of CNTs. It starts with a preview of two basic contact configurations, i.e., side contact and end contact, and measurements of contact resistance. The formation of Schottky barrier on a typical metal-semiconductor contact is then presented, aiming at looking for ways to reduce contact resistance from a theoretical point of view. The current techniques for improving CNT contact resistance are classified and summarized as well. The principles and applicabilities of these techniques are compared and discussed. A deep understanding of the forming mechanisms and improvement methods of contact resistance is critical in order to bring CNT-based devices from laboratory to the real-world technology.

Geospatial Application of the Water Erosion Prediction Project (WEPP) Model

Abstract. At the hillslope profile and/or field scale, a simple Windows graphical user interface (GUI) is available to easily specify the slope, soil, and management inputs for application of the USDA Water Erosion Prediction Project (WEPP) model. Likewise, basic small watershed configurations of a few hillslopes and channels can be created and simulated with this GUI. However, as the catchment size increases, the complexity of developing and organizing all WEPP model inputs greatly increases due to the multitude of potential variations in topography, soils, and land management practices. For these types of situations, numerical approaches and special user interfaces have been developed to allow for easier WEPP model setup, utilizing either publicly available or user-specific geospatial information, e.g., digital elevation models (DEMs), geographic information system (GIS) soil data layers, and GIS land use/land cover data layers. We utilize the Topographic Parameterization (TOPAZ) digital landscape analysis tool for channel, watershed, and subcatchment delineation and to derive slope inputs for each of the subcatchment hillslope profiles and channels. A user has the option of specifying a single soil and land management for each subcatchment or utilizing the information in soils and land use/land cover GIS data layers to automatically assign those values for each grid cell. Once WEPP model runs are completed, the output data are analyzed, results interpreted, and maps of spatial soil loss and sediment yields are generated and visualized in a GIS. These procedures have been used within a number of GIS platforms including GeoWEPP, an ArcView/ArcGIS extension that was the first geospatial interface to be developed in 2001. GeoWEPP allows experienced GIS users the ability to import and utilize their own detailed DEM, soil, and/or land use/land cover information or to access publicly available spatial datasets. A web-based GIS system that used MapServer web GIS software for handling and displaying the spatial data and model results was initially released in 2004. Most recently, Google Maps and OpenLayers technologies have been integrated into the web WEPP GIS software to provide significant enhancements. This article discusses in detail the logic and procedures for developing the WEPP model inputs, the various WEPP GIS interfaces, and provides example real-world geospatial WEPP applications. Further work is ongoing in order to expand these tools to allow users to customize their own inputs via the internet and to link the desktop GeoWEPP with the web-based GIS system.

The evidential foundations of probabilistic reasoning: toward a better understanding of evidence and its usage

The evidential foundations of probabilistic reasoning: toward a better understanding of evidence and its usage

Study on the Basic Configurations of Crank-Group Driving Mechanism

On the basis of parallelogram linkage, this paper introduced the working principles of a kind of new transmission mechanism:crank-group driving mechanism, its three basic configurations and their advantages and dis-advantages.

Elastic and photoelastic properties of KGd(WO4)2 single crystals

The elastic and photoelastic properties of a potassium-gadolinium tungstate KGd(WO4)2 crystal are determined. A complete matrix of elastic constants for the material is obtained for the first time and the velocity diagrams in the five most practically important planes are constructed on its basis. The coefficients of acoustooptic quality M 2 are measured for the first time for the crystal in the case of isotropic diffraction for all basic configurations of acoustooptic interaction, which makes it possible to reveal the directions of the most effective interaction.

Effects of Heterogeneity in Small π-Type Dimers: Homogeneous and Mixed Dimers of Diacetylene and Cyanogen.

The homo- and heterogeneous dimers of diacetylene (H-C≡C-C≡C-H) and cyanogen (N≡C-C≡N) were studied using ab initio electronic structure computations to probe the effects of heterogeneity on noncovalent interactions between systems with delocalized π electron networks. Full geometry optimizations and harmonic vibrational frequencies were performed using the robust coupled-cluster with single and double and perturbative triple excitations (CCSD(T)) method with the triple-ζ plus 2 sets of polarization functions TZ2P(f,d)++ basis set. Seven basic configurations were examined for each dimer (cross, stacked, parallel-slipped, parallel-tipped, linear, T-shaped and Y-shaped), but only four stationary points were identified on the potential energy surfaces (PESs) of the homogeneous cyanogen dimer and the mixed diacetylene/cyanogen dimer. Six previously characterized stationary points on the diacetylene dimer PES were re-examined with the CCSD(T) method and the TZ2P(f,d)++ basis set for consistency. Second-order Møller-Plesset perturbation theory (MP2) and CCSD(T) complete basis set (CBS) limit interaction energies were estimated using the explicitly correlated MP2-F12 and CCSD(T)-F12 methods in conjunction with the VQZ-F12 basis set. On the cyanogen dimer PES, the C2v T-shaped structure is the only minimum, with an average electronic interaction energy, Eint, of -1.96 kcal mol(-1) at the CCSD(T) CBS limit. The Cs Y-shaped structure (in agreement with previous results) is the global minimum on the diacetylene dimer PES, having a mean CCSD(T) CBS limit Eint of -1.75 kcal mol(-1). Three low-lying minima have been identified on the diacetylene/cyanogen dimer PES, a C∞v linear, a C2v cross, and a Cs parallel-slipped structure with average CCSD(T) CBS limit interaction energies of -2.00, -2.16, and -2.45 kcal mol(-1), respectively.

A Family of Biped Mechanisms With Two Revolute and Two Cylindric Joints

A family of biped spatial four-link mechanisms with two revolute and two cylindric joints is proposed in this paper. Three main categories, including eight configurations are put forward. The primary feature of these mechanisms is that they are made up of four links that are connected end to end through two revolute and cylindric joints, and among the links, two of them are designed as feet. These novel configurations are revealed by different methods and ways: The basic configurations are enumerated by traditional mechanism synthesis method; the conventional configurations are obtained by repetitious trial; the unique configurations are accidentally achieved by inspiration or intuition. Each of them has its own characteristic and can be an alternative option for biped robot design. Compared with most of the existing biped mechanisms, these configurations are simpler in structure and thus easier to control. The singular configuration is cleverly used rather than avoided to perform the walking and turning. Their structure descriptions and walking simulations are accomplished. Afterwards, the kinematic and stability analyses are studied, the design considerations are discussed, and foot-workspace analyses are carried out. Finally, four prototypes are developed to preliminary verify the feasibility of these proposed concepts.

Global optimization of multicomponent distillation configurations: 1. Need for a reliable global optimization algorithm

Nonazeotropic multicomponent mixtures are often separated into products by distillation configurations containing multiple distillation columns. One method of calculating the minimum vapor duty of a configuration is to sequentially calculate the minimum vapor duty of each mixture as it is split into two streams within a given column starting from the feed column. The other method simultaneously manipulates all the splits to yield the overall minimum vapor duty of the entire configuration. Of these two methods, the sequential minimization is attractive as it can be analytically solved. However, through extensive computations, we find that the sequential minimization method is not a valid substitute for the simultaneous minimization method. As the number of components in the feed increases, the fraction of the basic configurations for which sequential method yields a reasonable estimate decreases rapidly, thereby emphasizing the need for a more robust and reliable global optimization algorithm. © 2012 American Institute of Chemical Engineers AIChE J, 59: 971–981, 2013

Quantitative Reliability Assessment of Various Automated Industrial Substations and Their Impacts on Distribution Reliability

Considering six common types of substation automation systems (SASs), this paper not only performs a quantitative reliability evaluation of different automated industrial substations, but also assesses the impacts of various automated substations on the distribution system reliability. The technique is based on the event-tree methodology, reliability block diagram approach, and the concept-of-expectation method. The proposed approach is applied to the eight basic industrial substation configurations, and quantitative assessment of reliability benefits from the utilization of substation automation is conducted through a range of studies. The results show the value of using a systematic quantitative approach for investigating the effects of automation systems on substation reliability. The main contributions of this paper are: 1) to give explicit formulas for reliability evaluations of the automated industrial substation with arbitrary time duration of the automatic switching operation; 2) to prove the SAS with a faster automatic switching operation has a higher degree of improvement in the substation reliability indices; 3) to provide an effective tool for ranking the most reliable industrial substation configurations in the presence of various SASs; and 4) to quantitatively evaluate the effects of the automated substation with various SASs on distribution reliability indices.

Study on the Trajectory Planning of Hybrid-Driven Planar 3-RRR Mechanism

Hybrid-driven mechanism synthesis the constant speed motor and the servo motor as the power source through a multi degree of freedom mechanism. The text study on the trajectory planning of hybrid-driven planar 3-RRR mechanism. Firstly, based on compatible link combinations, all possible basic configurations of planar 3-dof kinematics chains were derived. Based on the requirements of hybrid-driven mode, the kinematics chains were selected one by one Planar 3-RRR mechanism was determined to be the research object finally. Then, based on the conclusions of inverse kinematics analysis, using the cubic spline function on point to point path planning, the servo motor rotation laws were presented. Comparing the different speed situation of constant motor, the influence trends on planning results were analyzed.