Basic Configurations Research Articles

Validation of magnetic resonance velocimetry for mean velocity measurements of turbulent flows in a circular pipe

Magnetic resonance velocimetry (MRV) is a versatile flow visualization technique that has been utilized for medical applications. Recently, MRV has been used to visualize engineering flows, but most engineers are still unfamiliar with the technique. In this paper, we introduce the basic principles and experimental configurations of MRV in detail and evaluate the accuracy of MRV applied to measure the mean velocity fields of turbulent flows in a circular pipe. A Philips Achieva 3.0 T Tx MRI scanner is used to provide a magnetic field and acquire resonance signals for flow visualization. Fully developed turbulent flows with Reynolds numbers of 6800, 9900 and 19400 were measured, and the axial mean velocity vectors were obtained with a spatial resolution of 0.5 mm for the three directions. Results show that the mean velocity profiles are in good agreement with reference data sets when properly scaled in both the inner and outer layers.

Two- and Three-dimensional Mid-Infrared Chemical Imaging.

This article describes the state-of-the-art in 2D and 3D tomographic mid-IR imaging and its current and potential applications in the imaging of material and biological systems with a focus on cells and tissues. 2D FTIR microscopy is first presented in terms of the basic experimental configurations of the technique, optics, data and image acquisition. This first section provides a basis for the ensuing discussion on 3D FTIR spectro-microtomography. In the second part, examples of 2D and 3D chemical imaging are given with a focus on the use of molecular chemical probes and probe-free applications, respectively.

X-FEM and FEM for Discontinuities Modelling: a Comparative Study

In this investigation, we present a comparative study on finite elements for capturing discontinuities by means of standard finite elements (FEM) or extended finite elements (X-FEM). For this purpose, several specimens containing geometrical and material discontinuities have been analyzed. The analysis covered different basic geometrical configurations, namely propagation of single crack-tip, propagation of double crack-tip, void and inclusion growth. The basic idea is to determine numerically values of certain fracture parameters, and to compare them with the results given by analytical solution. These main characteristics constitute the key to every fracture mechanics analysis. They are the base for the majority of failure criteria. Hence, determining these characteristics must be assessed as accurately as possible.

Elasto-acoustic response damping performance of a smart cavity-coupled electro-rheological fluid sandwich panel

The transient vibroacoustic response mitigation of a rectangular sandwich panel with an adaptive electro-rheological fluid core layer, and backed by a hard-walled reverberant rectangular parallelepiped acoustic enclosure, is investigated. The problem is analyzed in a multidisciplinary framework that involves the thin sandwich electro-rheological fluid-based plate model, the 3D wave equation for the acoustic enclosure domain, the first-order Kelvin–Voigt viscoelastic model for the electro-rheological fluid core material, the pertinent structure–fluid compatibility relation, and the inherently robust sliding mode control strategy. The generalized Fourier expansion method is utilized to set up the fully coupled system equations in the state–space domain, and the fourth-order Runge-Kutta time marching technique is then utilized to compute both uncontrolled and controlled coupled system responses in three basic external loading configurations. It is found that increasing the cavity depth has a substantial restraining effect on the overall sound pressure response levels, while the electro-rheological fluid-panel displacement response amplitudes experience only moderate reductions. Also, a purely passive electro-rheological fluid-based system is observed not to be very effective for vibroacoustic response suppression of the cavity-coupled structural system, while the overall success of the applied sliding mode control methodology in reasonable reduction of both panel displacement and sound pressure time response amplitudes is demonstrated. Furthermore, the control system authority with regard to the acoustic cavity pressure (panel displacement) is found to moderately (slightly) decrease as the cavity depth increases. Limiting cases are considered and accuracy of the suggested analytical model is checked against the output of an FEM package as well as with the accessible literature results. Moreover, the main components of a prospective experimental platform for verifying the performance of proposed vibroacoustic control system are briefly described.

Evaluation of RayXpert®for shielding design of medical facilities

In a context of growing demands for expert evaluation concerning medical, industrial and research facilities, the French Institute for radiation protection and nuclear safety (IRSN) considered necessary to acquire new software for efficient dimensioning calculations. The selected software is RayXpert® . Before using this software in routine, exposure and transmission calculations for some basic configurations were validated. The validation was performed by the calculation of gamma dose constants and tenth value layers (TVL) for usual shielding materials and for radioisotopes most used in therapy (Ir-192, Co-60 and I-131). Calculated values were compared with results obtained using MCNPX as a reference code and with published values. The impact of different calculation parameters, such as the source emission rays considered for calculation and the use of biasing techniques, was evaluated.

Adsorption of molecular hydrogen on coronene with a new potential energy surface.

Benchmark interaction energies between coronene, C24H12, and molecular hydrogen, H2, have been computed by means of high level electronic structure calculations. Binding energies, equilibrium distances and strengths of the long range attraction, evaluated for the basic configurations of the H2-C24H12 complex, indicate that the system is not too affected by the relative orientations of the diatom, suggesting that its behavior can be approximated to that of a pseudoatom. The obtained energy profiles have confirmed the noncovalent nature of the bonding and serve to tune-up the parameters of a new force field based on the atom-bond approach which correctly describes the main features of the H2-coronene interaction. The structure and binding energies of (para-H2)N-coronene clusters have been investigated with an additive model for the above mentioned interactions and exploiting basin-hopping and path integral Monte Carlo calculations for N = 1-16 at T = 2 K. Differences with respect to the prototypical (rare gas)N-coronene aggregates have been discussed.

Modified reversed superficial peroneal artery flap in the reconstruction of ankle and foot defects following severe burns or trauma

ObjectiveChallenges persist in the reconstruction of the ankle and the foot with exposed tendons, joints, and bones as a result of severe burns and trauma. In flap elevation involving the sensitive superficial nerve, the local nerve was always sacrificed to obtain an anesthetic donor site; however, such a procedure introduced the possibility of painful neuromas. In this study, we present a desired clinical application of a modified reversed superficial peroneal artery flap, in which the superficial peroneal nerve is preserved. MethodsFrom 2008 to 2015, 12 patients with ankle or foot defects were treated with the modified reversed superficial peroneal artery flap. The defects of the patients were caused by hot liquid scald (one patient), electrical injury (five patients), and trauma (six patients). The flap was utilized for covering defects on the ankle (seven patients) and the foot (five patients). The size of the flaps ranged from 4.0cm×6.0cm to 18.0cm×10.0cm. The superficial peroneal artery was involved in the flap, whereas the superficial peroneal nerve was spared by dedicate dissection. The reverse-flow flap was nourished by the superficial peroneal artery through the terminal peroneal artery perforator. ResultsThe obtained outcomes were satisfactory functionally and aesthetically. The flaps in 11 patients survived completely without complications, whereas partial necrosis occurred in a 78-year-old patient when the flap survived a week later during follow up. CT angiography revealed the stenosis of the popliteal artery. The wound healed after interventional treatment involving placing a stent and changing the dressings. Basic functions and configurations were salvaged in all cases. All patients were completely satisfied with the proposed flap and suffered no paresthesia in their lower leg. ConclusionExhibiting beneficial characteristics such as reliable blood supply, favorable thickness, wide rotating arc, and retention of major vessels and the superficial peroneal nerve, the modified reversed superficial peroneal artery flap is useful in the reconstruction of ankle and foot defects that would not cause any hypoesthesia of the foot.

Development and application of the integrated sealant test apparatus for sealing gaskets in tunnel segmental joints

An innovative apparatus has been developed in this study to investigate the coupled leakage and mechanical behaviors of gasketed segmental joints, subjected to the field loading conditions during the construction and operation stages. The basic principles and detailed configurations of this newly developed test setup are presented in detail. The test apparatus can be used to accurately monitor the water leakage pressure of segmental joints under various combinations of joint openings and offsets. A series of test sets, based on different characteristics of sealing gaskets used in segmental joints, were subsequently conducted to evaluate the functionality of the test setup. Testing apparatus was designed to evaluate the waterproof capacity of the three types of segmental joints (i.e., longitudinal/circumferential joint and T-joint (intersection of longitudinal and circumferential joints)) in the Nanjing Weisan Rd. Tunnel. The tested segments were cast with the identical gasket groove details and flanks to the practical tunnel segments. The correlation between gasket contact stress and supplied water pressure was analyzed. Comparison of the gasket sealant and mechanical behavior showed that there existed a “correlated zone”. The results showed that gasket-gasket interface, gasket-concrete gasket groove interface, damaged zones, and frame corners were the potential places of leakage in segmental joints. Finally, the results demonstrated that local concrete damages around the groove flank could serve as a water leakage channel and reduced the sealant performance of gasket.

Effect of Ions on H-Bond Structure and Dynamics at the Quartz(101)-Water Interface.

We use ab initio molecular dynamics simulations to study the effect of ions on the structure and dynamics of the quartz(101)-water interface. We study several IA (Na+, Rb+) and IIA (Mg2+, Sr2+) cations, with Cl- as counterion, adsorbed onto acidic, neutral, and basic surface configurations at 300 and 373 K. We find that both cations and anions can bond directly to the surface and perturb the local H-bond network. The adsorbed ions promote the formation of intrasurface H-bonds, as shown by vibrational density of states and orientations of the surface silanols. Both local and global structural correlations of the interfacial H-bond network are studied using a structural definition of the H-bond and a network correlation function. We find the ions' effect on the solvent structure exhibits a complex dependence on specific surface interactions. The structure-making properties of ions are enhanced at the quartz surface, particularly for ions adsorbed without a complete hydration shell, and the structuring effect extends beyond the first solvation shell. The ions have a lesser effect on solvent structure in solution, especially in the presence of counterions. In fact, cations that are the greatest "structure makers" at the surface are the greatest "structure breakers" when in solution with a counterion. Therefore, we find the ions cannot be simply classified as "structure making" or "structure breaking". We discuss the implications of these findings for the effect of ions on the dissolution rate, surface charge, and solvent structure.

Short channel effects in tunnel field-effect transistors with different configurations of abrupt and graded Si/SiGe heterojunctions

The heterojunction technique has recently been considered as an effective approach to simultaneously achieve a high on-current and low ambipolar off-leakage in tunnel field-effect transistors (TFETs). In this paper, we propose the various configurations of abrupt and graded Si/SiGe heterojunctions for TFETs and investigate their short-channel effects by using two-dimensional simulations. It is shown that the semiconductor bandgap has to be properly considered together with the drain-induced barrier thinning in studying short-channel effects because scaling down the bandgap considerably deteriorates short-channel effects in TFETs. Among the basic configurations of Si/SiGe heterojunctions, the slantingly graded Si/SiGe heterostructure is most excellent in optimizing the electrical characteristics of the extremely scaled TFETs without short-channel effects. The slantingly graded Si/SiGe TFET with superior short-channel performance exhibits a potential device for low power and high packaging density integrated circuits.

TASKS STATEMENT FOR MODERN AUTOMATIC CONTROL THEORY OF UNDERWATER COMPLEXES WITH FLEXIBLE TETHERS

The definition of a new class of control objects is proposed. It is an underwater complex with flexible tethers (UCFT) for which there is the need to automate motion control under uncertainty and nonstationarity of own parameters and external disturbances. Classification of marine mobile objects and characteristics of the flexible tethers as UCFT elements is given. The basic UCFTs configurations that are used in the implementation of advanced underwater technologies are revealed. They include single-, double- and three-linked structures with surface or underwater support vessels and self-propelled or towed underwater vehicles. The role of mathematical modeling in tasks of motion control automation is shown. The tasks of UCFT mathematical modeling are formulated for synthesis and study of its automatic control systems. Generalized structures of mathematical models of UCFT basic elements are proposed as the basis for the creation of simulating complex to study the dynamics of its motion. The tasks of UCFT identification as a control object are formulated. Their consistent solution will help to obtain a UCFT mathematical model. The basic requirements for UCFT automatic motion control systems are determined. Their satisfaction will ensure implementation of selected underwater technology. Areas of development of synthesis methods of UCFT automatic control systems are highlighted.

Recent Development in the Distributed Fiber Optic Acoustic and Ultrasonic Detection

Distributed acoustic sensors provide a powerful instrumentation for ultrasound testing to identify the internal crack and deformation with the location for assessing structural conditions and predicting the potential structural failure. This paper provides a tutorial review of the milestones leading to the development of the distributed acoustic sensor based on Rayleigh back scattering. It offers discussion on basic principles, optical configurations and system design requirement, various detection schemes, performance limitations and applications for the maximum measurable frequency, minimum detectable strain and highest spatial resolution. A final comment on the prospects of the further developments is presented.

Compile- and run-time approaches for the selection of efficient data structures for dynamic graph analysis.

Graphs are used to model a wide range of systems from different disciplines including social network analysis, biology, and big data processing. When analyzing these constantly changing dynamic graphs at a high frequency, performance is the main concern. Depending on the graph size and structure, update frequency, and read accesses of the analysis, the use of different data structures can yield great performance variations. Even for expert programmers, it is not always obvious, which data structure is the best choice for a given scenario.In previous work, we presented an approach for handling the selection of the most efficient data structures automatically using a compile-time approach well-suited for constant workloads.We extend this work with a measurement study of seven data structures and use the results to fit actual cost estimation functions. In addition, we evaluate our approach for the computations of seven different graph metrics. In analyses of real-world dynamic graphs with a constant workload, our approach achieves a speedup of up to 5.4× compared to basic data structure configurations.Such a compile-time based approach cannot yield optimal results when the behavior of the system changes later and the workload becomes non-constant. To close this gap we present a run-time approach which provides live profiling and facilitates automatic exchanges of data structures during execution. We analyze the performance of this approach using an artificial, non-constant workload where our approach achieves speedups of up to 7.3× compared to basic configurations.

Overview of Architectures with Arduino Boards as Building Blocks for Data Acquisition and Control Systems

Standard SBCs (Single Board Computer) with number of standard shields and sensors can be used as building blocks for rapid development of network of intelligent devices with sensing, control and Internet access. Arduino family of boards having high popularity and large number of sold units featuring open access, reliability, robustness, standard connections and low prices, possesses large potential for implementation of autonomous remote measurement and control systems of various levels of complexity. As Arduino boards can function independently, they are complete small computer platforms that can perform various tasks requiring some kind of interaction with the outer world. Arduino boards can be used and programmed in various ways, and can be arranged in various combinations forming some typical implementation architectures that this paper discusses. Starting from basic and simple configurations, more advanced are gradually considered from the aspects of chosen way of programming and combining with other boards. Special attention is devoted to NodeJS as programming platform for Arduino boards and considerations of libraries used with Arduino boards like Johnny-Five, Galileo-io firmata equivalent, mraa library and other ways of program access to GPIO like Linux Sysfs. As typical representatives of Arduino boards’ family, the Arduino Uno, Arduino Due and Arduino Galileo were selected, with justification that all other not mentioned boards are somewhere between those selected, according to official hardware specifications.

Multi-Channel Surface Electromyography Electrodes: A Review

This paper is a review of multi-channel surface electromyography (sEMG) electrode used in the research for investigating the properties of muscles. Over 300 papers from five recognized journals were examined from the year 2000 to 2013 with only 64 stating the use of multi-channel electrodes in their research. The review determined that multi-channel electrodes can be classified as linear array or 2D array electrodes. The 2D array is the basis for developing the high-spatial-resolution sEMG (HSR-sEMG) or high density sEMG (HD-sEMG). The important factors considered in this review of the electrodes are: 1) the material used; 2) the inter-electrode distance; and 3) the configuration for the collection of the electromyography signals. The basic configurations of the sEMG electrodes are monopolar, bipolar, and double differential. It was found that the majority of the linear array electrodes were used to collect either bipolar or double differential signals. The 2D array electrodes were used to collect monopolar signals. The HSR-sEMG electrodes used a normal double differentiating filter, referred to as Laplacian configuration. The HD-sEMG has versatility being able to collect all types of signals, such as monopolar, bipolar, double differential, or signals filtered by Laplacian configuration.

Condensation on nanorods by molecular dynamics

Many recent experimental studies have been conducted on constructing nanorods and nanowires to use in a wide range of applications. In this study, molecular dynamics is used to directly examine the condensation rate of nanorods and the results are compared with other basic configurations such as cubes or spheres. According to previous studies conducted by Suh and Yasuoka [J. Phys. Chem. B 115, 10631 (2011); 116, 14637 (2012)], a simple change in the configuration of the seed produces a shape effect, where the curvature of the solid seed surface directly affects the growth generating an orderly difference depending on the curvature. Nanoscale cuboids or nanorods were studied to find an aspect ratio effect when condensation occurs on the surface. Various aspect ratios were examined for different nanorod sizes over a wide range of supersaturation ratios. The results show that the growth rate of the nanorod is independent of the supersaturation ratio, which was also observed for the sphere and cube. The growth rate for the rod fell between those of the cube and the sphere, and this is due to an increase in the surface area of the nanorod compared to the cube and curvature effect in comparison with the sphere. A clear size dependence of the seed was observed, which is also similar to the cube and sphere. Furthermore, no aspect ratio influence was seen for the growth rate. This does not mean that the actual amount of condensation is the same for longer seeds, but rather from the definition of the growth rate, the amount of accumulation per unit area is the same for all seed lengths.

Creativity for Invention Insights: Corporate Strategies and Opportunities for Public Entrepreneurship

This paper introduces and describes the invention-insight sample space and uses it to describe the creative process of discovering invention insights — the essential combinations of elements of knowledge to envision the basic working configurations of inventions, the working ideas for new technologies. Evidence about invention insights and about corporate strategies to promote them is viewed in the context of the paper’s description of the invention-insight discovery process. Then that description is used (1) to identify a novel new opportunity — initiation of policies to stimulate invention insights that directly combine unusually large numbers of knowledge elements — for public sector entrepreneurship to speed the pace of technological progress and the opening up of altogether new areas of science and technology, and (2) to delimit the appropriate form of policy — promotion of competition and the free exchange of ideas — to exploit the opportunity. With sufficient uncertainty in the search for insights, pre-invention-insight ideas in themselves should ideally be freed from the restrictions of intellectual property.

New Single-Input, Multiple-Output Converter Topologies: Combining Single-Switch Nonisolated dc-dc Converters for Single-Input, Multiple-Output Applications

This article presents a methodology that allows the development of new converter topologies for single-input, multiple-output (SIMO) from different basic configurations of single-input, single-output dc-dc converters. These typologies have in common the use of only one power-switching device, and they are all nonisolated converters. Sixteen different topologies are highlighted, and their main features are explained. The 16 typologies include nine twooutput-type, five three-output-type, one four-output-type, and one six-output-type dc-dc converter configurations. In addition, an experimental prototype of a three-output-type configuration with six different output voltages based on a single-ended primary inductance (SEPIC)-Cuk-boost combination converter was developed, and the proposed design methodology for a basic converter combination was experimentally verified.

Electromagnetic wave energy flow control with a tunable and reconfigurable coupled plasma split-ring resonator metamaterial: A study of basic conditions and configurations

We propose and study numerically a tunable and reconfigurable metamaterial based on coupled split-ring resonators (SRRs) and plasma discharges. The metamaterial couples the magnetic-electric response of the SRR structure with the electric response of a controllable plasma slab discharge that occupies a volume of the metamaterial. Because the electric response of a plasma depends on its constitutive parameters (electron density and collision frequency), the plasma-based metamaterial is tunable and active. Using three-dimensional numerical simulations, we analyze the coupled plasma-SRR metamaterial in terms of transmittance, performing parametric studies on the effects of electron density, collisional frequency, and the position of the plasma slab with respect to the SRR array. We find that the resonance frequency can be controlled by the plasma position or the plasma-to-collision frequency ratio, while transmittance is highly dependent on the latter.

Điều khiển các dây chuyền sản xuất linh hoạt

In the maner of system theory the manufacturing systems will be seen as a complexity of technological process with some more of less flexible control strategies. In this paper a complexity of technological process is considered. Some basic configurations and adjustement possibilities of flexible manufacturing systems are also provid.