Effects Of Configuration Parameters Research Articles

Configurational explorations and optimizations of a phase change material based thermal energy storage with tube bundle

Compared to the extensive attentions paid to latent heat thermal energy storage (LHTES) with single tube in shell, the configurations of multiple serpentine tubes as bundles are less explored. Maldistributions of heat transfer and temperature along the heat transfer fluid (HTF) tube and charging process are barely discussed and improved. In this study, a numerical model is developed and validated. Targeting to charging process, effects of configurational parameters are revealed in detail with a focus on the maldistributions. Results show that a smaller tube pitch and a larger tube branch number benefit the charging time and charging power, while the dominant influence factor could switch from Reynolds number to heat transfer area. Moreover, the phase change material (PCM) temperature maldistribution exists for more than 50% of the charging time. Moreover, a chart with five classified zones to evaluate the charging time is proposed. Cases with unevenly allocated HTF tubes are further investigated. It is found that as the HTF inlet mass flow rate is 0.167 kg/s, the melting time of the two-region case and three-region case could be reduced by 11.1% and 14.1%, respectively. There exists a pseudo-minimum charging time when the HTF inlet mass flow rate is 1.667 kg/s.

An adjustable low frequency vibration isolation with high-static-stiffness low-dynamic-stiffness property using a novel negative stiffness element

A vibration isolator with a novel negative stiffness element (NSE) configured with two electromagnetic springs in parallel was proposed in this study. The electromagnetic force and stiffness model of NSE was built based on the Ampere current model and filament method, the effect of configuration parameters on the negative stiffness was investigated in detail. The linear negative stiffness principle was proposed based on the impact of height difference on the nonlinear component sign of the negative stiffness, and the linear negative stiffness parameter design strategy for NSE was also developed. The isolator prototype was fabricated with the parameter design result, and the correctness of modeling and principle for linear negative stiffness were validated by magnetic force measurement. A series of experiments under different coil currents and vibration amplitude was conducted. The results show that high-static-stiffness and low-dynamic-stiffness property of the isolator is realized, the resonant frequency is 3.85 Hz with the coil current is 1A is reduced by up to 58.5% compared with the resonant frequency when coil without energized, the isolation bandwidth has been stretched and can be adjusted by coil current and performance has been significantly improved also. In addition, the isolator is stable and the performance is not deteriorator under different vibration amplitudes.

Fast Performance Modeling across Different Database Versions Using Partitioned Co-Kriging

Database systems have a large number of configuration parameters that control functional and non-functional properties (e.g., performance and cost). Different configurations may lead to different performance values. To understand and predict the effect of configuration parameters on system performance, several learning-based strategies have been recently proposed. However, existing approaches usually assume a fixed database version such that learning has to be repeated once the database version changes. Repeating measurement and learning for each version is expensive and often practically infeasible. Instead, we propose the Partitioned Co-Kriging (PCK) approach that transfers knowledge from an older database version (source domain) to learn a reliable performance prediction model fast for a newer database version (target domain). Our method is based on the key observations that performance responses typically exhibit similarities across different database versions. We conducted extensive experiments under 5 different database systems with different versions to demonstrate the superiority of PCK. Experimental results show that PCK outperforms six state-of-the-art baseline algorithms in terms of prediction accuracy and measurement effort.

Research on sailing range of thermal-electric hybrid propulsion underwater glider and comparative sea trial based on energy consumption

Underwater glider is becoming an increasingly important tool for exploring the ocean. As the underwater tasks become more challenging, it puts forward higher requirements for the endurance of electric underwater gliders. This paper proposes an operation principle for the underwater glider jointly driven by the ocean thermal energy and the electrical energy, which has the advantages of both electric underwater glider and thermal underwater glider. Based on the proposed operation principle, a universal energy consumption model and sailing range equation suitable for the electric, thermal and hybrid propulsion underwater gliders are established. Taking the sailing range, sailing range difference and sailing range ratio as the evaluation indexes, the effects of configuration parameters and navigation parameters on the endurance of three underwater gliders are analyzed. The results show that the endurance and endurance advantage of hybrid propulsion underwater glider can be improved with greater volume change rate of phase change material (PCM), heavier energy carrier and smaller average power of the task sensor, and its high performance can also be maintained with a weight ratio of PCM close to the critical value. Meanwhile, it is beneficial to obtaining stronger endurance for the hybrid propulsion glider during its operation by setting larger diving depth as well as smaller gliding angle and volume change of oil within the design range. Finally, the hybrid propulsion prototype and Petrel-II electric underwater glider are deployed to carry out the comparative sea trial, which verifies the correctness of sailing range equation and the availability of prototype. The results show that the hybrid propulsion underwater glider has a better energy consumption economy than the electric underwater glider.

Mathematical modeling of the heat exchange in a stepped solar still

A mathematical model for investigating warm performance of the ventured sunlight based still which is not performed in most of the previous studies. is developed in this study. Based on the proposed model, a computer program (using Pascal language) is carried out. A stepped solar still consists of five small steps(0.002 m depth, 0.2 m width and 1.0 m length). The effect of configuration parameters on the stepped productivity and efficiency such as the still width (b_s), depth of water (d_w), tray width (W) and the height of tray (H) is considered. Comparing thermal performance of the stepped solar still with that of the conventional one shows that the stepped solar still is more efficient. Correlations of the got results with those introduced in the past investigations have been done, prompt an approving the proposed mathematical model. The outcomes show that, the every day productivities for the traditional and ventured sun based stills are discovered to be 4.0 and 4.51 (kg/m2day); separately. The Daily productivity of the regular and ventured sunlight based stills are 61.48% and 81.85%, individually.

Design and experimental validation of a vibration isolator with high-static low-dynamic stiffness and operating point variable property

Vibration isolator with high-static low-dynamic stiffness property has been researched extensively, but the isolator’s stability and performance will be deteriorated with the operation point variation. In this article, a vibration isolator that operation point can be variable was proposed, and it was constructed by combining a coil spring and flexible leaf springs with a negative stiffness magnet spring in parallel. Unlike previous studies, this article focuses on the realization of the high-static low-dynamic stiffness characteristic of the isolator, and the operation point of the vibration isolator can be varied in a certain range. The effects of configuration parameters on the negative stiffness are investigated in detail. Furthermore, the designing procedure to realize the linear negative stiffness with the expected magnitude and range was also developed. A prototype was installed and the vibration transmissibility of the system at different operation points was measured, the experimental results indicated that the isolator can be kept stable in different operation points, and the performance does not deteriorate with the variation of the operation point. The effectiveness of the designing procedure of the realization of linear negative stiffness with the expected magnitude and range and the variable of the operation point of the isolator was validated.

Effects of Configuration Parameters on the Deformation and Fracture Behaviors of TiBM <sub>2</sub>/Cu Composites with Network Structure: A Numerical Approach Using an Enhanced Finite Element Model

Effects of Configuration Parameters on the Deformation and Fracture Behaviors of TiBM <sub>2</sub>/Cu Composites with Network Structure: A Numerical Approach Using an Enhanced Finite Element Model

Modeling and experimental characterization of a multi-point loaded piezocomposite beam for actuation and energy harvesting

This article proposes a multi-point support and inertial loading for beam-like piezocomposite vibration energy harvesters as an alternative to the common cantilevered beam configuration. In the proposed configuration, symmetrical overhanging free segments extend beyond two interior pinned supports, and tip masses are attached to the free ends for inertial tip-loading. The dynamic response of this multi-point loaded beam can be significantly altered by varying two configuration parameters: the support location and tip-loading. In this article, the transverse vibration due to harmonic excitation of a piezocomposite beam in this multi-point configuration is analyzed. The effects of configuration parameters on the natural frequency and curvature shapes of the beam are shown. Results from experimental testing of several support locations and tip masses are compared with analytical predictions, and it is demonstrated that the fundamental frequency of this system can be tuned by adjusting the support location and tip-loading. Comparisons of the output-to-input power ratios for the different configurations during vibration energy harvesting are also made, which demonstrate increased strain-normalized transduction for the multi-point configurations over a reference cantilevered beam. This article concludes with a discussion of the potential application of this configuration as a vibration energy harvester.

Fluid-thermal-structural analysis and structural optimization of spiral-wound heat exchanger

Based on the liquid-solid-thermal coupling method, the effects of configuration parameters on the flow characteristic, the heat transfer performance and the stress distribution on the tube bundle of spiral-wound heat exchanger (SWHE) were numerically studied. The results show that the shell-side flow patterns change from cross flow into oblique flow and the overall heat transfer coefficient increases firstly and then decreases with the increase of the wingding angle. The maximum stress intensity decreases firstly with the increase of the inlet flow rate and then decreases. The thermal stress takes a leading position in the tube bundle stress distribution attributed to the higher heat transfer temperature difference. With the inlet flow rate increasing, the heat transfer is enhanced and the temperature difference decreases which result in the decrease of the proportion of thermal stress and the increase of the impact of the primary stress. The optimal structure was obtained by the Multi-Objective Genetic Algorithm based on the Genetic Aggregation response surface. Compared with the original structure, the average comprehensive performance of three optimal candidates of SWHE increase by 57.64% and the maximum stresses intensity of the tube bundle are far less than the material allowable stress.

Investigations on the two-dimensional aperiodic plasma photonic crystals with fractal Fibonacci sequence

In this paper, the properties of photonic band gaps (PBGs) and defect modes of two-dimensional (2D) fractal plasma photonic crystals (PPCs) under a transverse-magnetic (TM) wave are theoretically investigated by a modified plane wave expansion (PWE) method. The configuration of 2D PPCs is the square lattices with the iteration rule of the Fibonacci sequence whose constituents are homogeneous and isotropic. The proposed 2D PPCs is filled with the dielectric cylinders in the plasma background. The accuracy and convergence of the present modified PWE method also are validated by a numerical example. The calculated results illustrate that the enough accuracy and good convergence can be achieved compared to the conventional PWE method, if the number of meshed grids is large enough. The dispersion curves of the proposed PPCs and 2D PPCs with a conventional square lattice are theoretically computed to study the properties of PBGs and defect modes. The simulated results demonstrate that the advantaged properties can be obtained in the proposed PPCs compared to the 2D conventional PPCs with similar lattices. If the Fibonacci sequence is introduced into the 2D PPCs, the larger PBGs and higher cutoff frequency can be achieved. The lower edges of PBGs are flat, which are originated from the Mie resonances. The defect modes can be considered as the quasi-localized states since the Fibonacci sequence has the self-similarity and non-periodicity at the same time. The effects of configurational parameters on the characters of the present PPCs are investigated. The results show that the PBGs and defect modes can be easily manipulated by tuning those parameters.

Prediction of cyclic behavior of WUF-W connections with various weld access hole configurations using nonlinear FEA

The welded unreinforced flange-welded web (WUF-W) moment connection is one of seven prequalified connections for the special moment frames (SMF) specified in AISC 358-10. Previous studies reported that some WUF-W connections with a steep access hole slope failed before completing a loading cycle of 4% drift ratio. For investigating in detail the effect of access hole geometry including access hole slopes on the connection behavior, experimental tests require excessive costs and efforts because there are the large number of combinations of configuration parameters for access hole geometry. In this study, the cyclic behavior of WUF-W connections is evaluated using three-dimensional nonlinear finite element (FE) analyses with an adequate solid element and failure index. Based on the results of FEA, the effect of configuration parameters on the connection behavior is investigated.

Dynamic behavior of staggered triangular honeycomb cores under in-plane crushing loadings

AbstractA reliable finite element model was employed to investigate the effects of configuration parameters and impact velocity on the in-plane deformation mode and dynamic plateau stress of staggered triangular honeycomb cores at impact velocities 3–300 m s–1 under in-plane crushing loadings. At different impact velocities, ‘>’-, ‘<’-shaped, and ‘I’-shaped deformation modes appear in turn. The effects of configuration parameters on the deformation modes are discussed qualitatively. When all configuration parameters are kept constant, the mean in-plane dynamic plateau stress is proportional to the square of impact velocity; for a given impact velocity, the mean in-plane dynamic plateau stress is related to the ratio of cell-wall thickness to edge length by power laws and to the expanding angle by complicated curves. Mean in-plane dynamic plateau stresses are expressed by empirical equations in terms of configuration parameters and impact velocity based on our simulation results.

Self-Field AC Losses on Ag-BSCCO(2223) Multifilamentary Tapes with Different Filament Arrangements

The influence of the geometrical parameters on the behaviour of the AC losses in multifilamentary Ag-BSCCO(2223) tapes is being more and more evident. Recently, the effects of configurational parameters like the ratio between the overall width and thickness of tapes without barriers as well as their precise arrangements has been put in evidence either theoretically or experimentally. With the goal to go deeper into the comprehension of this relation, we characterized a serie of multifilamentary tapes with gradually different filament arrangements. They were measured in a self-field AC transport system at different frequencies, for current values up to the critical state. The results so obtained are discussed taking into account of some theoretical models.

Quasi-exact linear spring countergravity system for robotic manipulators

A new quasi-exact linear spring counterbalancing system for general manipulators is theoretically stated and experimentally tested on a parallelogram manipulator. The effect of configuration parameters on developed balancing torque is studied, which gives insight into possible active application of the presented configuration. Quasi-exact balancing of gravitational torque is achieved without any assumption on initial spring length thus avoiding classical shortcomings arising from perfect spring equilibrator theory.