Geometrical Parameters Of System Research Articles

Stacked ensemble learning approach for PCM-based double-pipe latent heat thermal energy storage prediction towards flexible building energy

Dynamic performance prediction of the PCM-based double-pipe latent heat thermal energy storage (LHTES) system plays an important role for building peak load shifting. This study presents a stacked ensemble learning framework for the phase change performance prediction of LHTES systems. The proposed model has a two-layer structure involving base and meta models: Regression Tree, Support Vector Regression and Linear Regression. Sensitivity analysis has been utilized for the feature extraction considering possible geometrical and physical parameters of LHTES systems with a fixed PCM volume that can store 0.94 kWh of energy within 255 min. Case studies show that the proposed model outperforms the base models in terms of both prediction accuracy and robustness. Compared with base models, the proposed model has a maximum 7.82% (charging) enhancement in Mean Absolute Percentage Error (MAPE) over all-range data sets and a maximum 16.43% enhancement in MAPE for the initial discharging stage, and has more stable predictive results within the high accuracy zone (accuracy > 95%) with a maximum 7.3% (charging) increase in the distribution density over all-range data sets and a maximum interquartile range reduction of 25.6% (middle discharging stage) in Mean Absolute Error. Application of the proposed model achieved more building peak load reduction.

Morphological Relaxation of Strained Epitaxial Films for Stripe‐Geometry Devices

AbstractOne of the major issues when reducing the channel length in strained transistors is the stress relaxation that significantly degrades the carriers mobility. A new morphological evolution is reported here, describing the relaxation of a strained epitaxial film deposited on a pattern characterized by stripe geometry, both paradigmatic of two‐dimensional (2D) like systems, and characteristic of many devices. The thermodynamic surface diffusion framework accounting for elasticity and capillarity is investigated. The former is solved in two dimensions thanks to the Airy formalism. The resulting dynamical Schrödinger‐like equation governing the film shape evolution is then solved thanks to a decomposition on eigenmodes. It reveals different developments depending upon the system's geometric parameters and the time scale. Mass transfer occurs toward the relaxed areas and creates a ridge at the nanolayers edges, controlled by the geometry and the scale of the structure. These results allow to refine the potential control of electronic properties via the geometry of a system.

Hydrodynamic performance of wave energy converter integrated with pile restrained floating structure near a partially reflecting seawall

The integration of a Wave Energy Converter (WEC) with a Pile-Restrained Rectangular Floating Breakwater (PRFB) in the presence of a partially reflecting vertical seawall is analysed to enhance the hydrodynamic performance and WEC efficiency of the integrated breakwater-WEC device based on small amplitude wave theory using the Boundary Element Method (BEM). The rectangular floating breakwater is designed to have heave motion with a pile-restrained floating structure placed in a position to attenuate the incoming wave in the transmitted region and the linear power take-off (PTO) damping is employed to calculate the absorbed power. The study is performed to understand the effectiveness of wave energy conversion and its hydrodynamic performance due to changes in the seawall's porosity, relative structural width, relative structural draft, wave energy conversion power take-off damping coefficients, and the relative gap of the WEC integrated with PRFB from the seawall. The study demonstrated that in the presence of a fully reflecting seawall, the wave energy extraction is enhanced for the integrated WEC system without compromising the defined threshold wave reflection coefficient but at the expense of a constrained range of wavenumbers that correspond near the system's fundamental natural frequency. Moreover, the capture width ratio is noted to be higher for relatively smaller structural drafts, while the wave reflection coefficient shows precisely the reverse trend. However, under such circumstances, the integrated WEC system operates as a motion-trapping structure, especially when the reflection coefficient of the seawall, CR≥0.75. Thus, the present study will assist the designer in determining the appropriate degrees of efficiency of the WEC device without sacrificing hydrodynamic performance by fine-tuning the hybrid floating breakwater system's geometrical parameters.

Optimization of Dynamically Loaded Nonlinear Technical Systems

Technological progress is impossible without new innovative developments, discoveries, inventions. Modern nonlinear technical systems cannot do without the use of friction units, which are various gears, connections, as well as complex nodes and devices. The geometrical parameters of the railway-rolling stock system were optimized when moving in curves of small radius. A unique roller rig was used to carry out model tests using the method of physical and mathematical modeling. It is proposed a method for increasing the efficiency of friction systems, which is based on fundamental research in the field of mechanics of contact friction interaction of solids. One of the technical solutions implemented on the basis of this study is the development of technology and technological equipment for increasing the traction force of a locomotive and increasing the service life of wheelsets. The theoretical basis of this technology is the anisotropy of friction junctions formed by thermos metal plating of the wheel working surfaces.

EXPERIMENTAL STUDY OF SURFACE ROUGHNESS EFFECT ON THE RHEOLOGICAL BEHAVIOR OF MR FLUID

Magnetorheological (MR) fluids are classified as smart materials. They are non-homogeneous substances of complex composition and are characterised by complex rheological properties. In addition, the characteristics of their behaviour can be actively affected by the magnetic field, both in terms of its value and spatial orientation. This paper presents the results of shear stress measurements of a commercial magnetorheological fluid using a plate-plate type geometry with a modified working surface. The purpose of the study was to determine the effect of changing the roughness of the measuring plate on the obtained shear stress results. Controlled shear rate tests and Magneto Sweep measurements were carried out for three MR fluid layer heights. The tests were carried out at magnetic field induction in the range of 0 to 680 mT. The study showed that the measurement system's geometric parameters significantly affect the MR fluid's behaviour under test. It was shown that increasing the surface roughness can increase or decrease the measured value of shear stress depending on the test parameters.

Electrokinetic separation of cfDNA in insulator-based dielectrophoresis systems: a linear model of cfDNA and investigation of effective parameters

In this study, a comprehensive numerical simulation was done to investigate the electrokinetic translocation of cfDNA molecule as well as the possibility of its detection and separation in insulator based dielectrophoresis (iDEP) systems. Modeling was done for the first time by solving the Poisson equation for the electrical potential, Naiver–Stokes (NS) equation for the fluid flow and energy equation for the heat transfer in the system and considering a coarse-grained bead-spring model to describe the conformational and geometrical changes of cfDNA molecule. The effect of the geometrical parameters of the system, the initial orientation of the molecule, electrical conductivity of the solution and zeta potential of the wall was investigated on the translocation and the minimum voltage required for cfDNA trapping. When the ratio of the inlet height to the constriction zone height is large enough, cfDNA molecules cannot pass through the nanopore and trap in the constriction zone. Also, it was found that the electrical conductivity of the solution is a limiting parameter to directly isolate cfDNA from pure plasma without dilution due to significant increase in the temperature of the system. Our results demonstrate the enormous potential of iDEP systems for rapid detection of cfDNA from diluted plasma under special electrical potential and geometrical parameters of the iDEP systems.

System calibration method for infrared phase measuring deflectometry

Infrared phase measuring deflectometry (IR PMD) is a kind of PMD technique, which exploits IR light as a display screen, therefore it can effectively improve the measurement accuracy by reducing the environmental noise, especially the influence of the ambient light. However, data accuracy of a deflectometric measurement system is mainly determined by calibration procedure, which establishes the relationship between phase map and depth data. In this paper, a novel using fringe projection profilometry (FPP) technology based system calibration method is proposed to obtain the geometrical parameters of the IR PMD system. A composite plane calibration board with diffused and specular surface has been designed to determine the X, Y, and Z coordinates of this specular plane at a reference position, which is located at a certain reference position parallel to the ground glass (used as the IR screen) to obtain the system parameter d. Experimental results demonstrate that 3D shape of specular objects can be effectively and accurately measured using the proposed geometrical calibration method.

Light Curve Analysis and Period Study of Two Eclipsing Binaries UZ Lyr and BR Cyg

Two eclipsing binary systems, UZ Lyr and BR Cyg, are semi-detached types whose secondary component fills its Roche lobe. Although radial velocity and light curves of these systems have already been investigated separately, both their radial velocity and light curves are analyzed simultaneously for the first time in the present study. Also, the orbital period changes of these systems are studied. Our results show that the mass transfers between components have negligible effects on the orbital period changes of these systems, but two light travel time effects are the reasons for the periodic behavior of the O − C curve for UZ Lyr. We could not remark more information about orbital period changes for BR Cyg, but we find a new orbital period for it. By radial velocity and light curve analysis, we find a cold spot on the secondary component of BR Cyg. The new geometrical and physical parameters of both systems are obtained and their positions on the H-R diagram are demonstrated.

Entropy analysis of Poiseuille nanofluid flow in a porous channel with slip and convective boundary conditions under magnetic field

Purpose This study aims to expose the flow phenomena and entropy generation during a; magnetohydrodynamic (MHD) Poiseuille flow of water-based nanofluids (NFs) in a porous channel subject to hydrodynamic slip and convective heating boundary conditions. The flow caused by the uniform pressure; gradient between infinite parallel plates is considered steady and fully developed. The nanoparticles; namely, copper, alumina and titanium oxide are taken with pure water as the base fluid. Viscous dissipation and Joule heating impacts are also incorporated in this investigation. Design/methodology/approach The reduced governing equations are solved analytically in closed form. The physical insights of noteworthy parameters on the important flow quantities are demonstrated through graphs and analyzed elaborately. The thermodynamic analysis is performed by calculating entropy generation; rate and Bejan number. A graphical comparison between solutions corresponding to NFs and regular fluid in the channel is also provided. Findings The analysis of the results divulges that entropy generation minimization can be achieved by an appropriate combination of the geometrical and physical parameters of thermomechanical systems. It is reported that ascent in magnetic parameter number declines the velocity profiles, while the inverse pattern is witnessed with augmentation in hydrodynamic slip parameters. The temperature dissemination declines with the growth of Biot numbers. It is perceived that the entropy generation rate lessens with an upgrade in magnetic parameter, whereas the reverse trend of Bejan number is perceived with expansion in magnetic parameter and Biot number. The important contribution of the result is that the entropy generation rate is controlled with an appropriate composition of thermo-physical parameter values. Moreover, in the presence of a magnetic field and suction/injection at the channel walls, the shear stresses at the channel walls are reduced about two times. Practical implications In various industrial applications, minimizing entropy generation plays a significant role. Miniaturization of entropy is the utilization of the energy of thermal devices such as micro heat exchangers, micromixers, micropumps and cooling microelectromechanical devices. Originality/value An attentive review of the literature discloses that quite a few studies have been conducted on entropy generation analysis of a fully developed MHD Poiseuille flow of NFs through a permeable channel subject to the velocity slip and convective heating conditions at the walls.

Parametric analysis and optimization of a latent heat thermal energy storage system for concentrated solar power plants under realistic operating conditions

High-temperature latent heat thermal energy storage (LHTES) systems are currently being considered for integration into concentrated solar power (CSP) plants; however, the challenge is to properly design the LHTES system under real-world operating conditions. Thus, this numerical investigation studied the effects of the LHTES system's design parameters on its performance under periodic steady-state with charging and discharging ‘cutoff’ temperatures to mimic its real-world operation. The study found that with the incorporation of cutoff temperatures, the system's specific energy and storage effectiveness decreased by 74% and 68%, respectively, due to lower useful charging and discharging times. Furthermore, the study demonstrated that the system's useful charging and discharging time could be augmented by increasing the shell radius (R) or length (L) of the system, or by decreasing the system's tube radius (ro) or the velocity of the heat transfer fluid (um) that flows through the system. The system's geometrical parameters (R, L, and ro) and um also substantially influenced its performance, but in a different manner than their influence on charging-discharging times. For example, increasing R deteriorated the system's performance substantially. Thus, we proposed optimized designs that achieved high charging-discharging times as well as good performance levels, using the response surface methodology.

Performance evaluation of venturi aeration system

The venturi aeration is an effective practice to increase the dissolved oxygen accessibility in the water bodies. This study aims to optimize the various geometrical parameters of the venturi aeration system. A non-dimensional technique was applied to find the optimum performance of various geometric parameters i.e. throat lengths (tl), number of air holes (N), and converging and diverging angles (α and β). These experiments have been carried out using 1124 L capacity of tank having dimensions of 105 cm long, 105 cm wide and 102 cm deep. The experiments were conducted at a constant flow velocity of water (1.096 m/s) with varying throat length (tl = 20–100 mm keeping 20 mm as interval between two consecutive length), number of air holes (N = 1–17 at an equal hole to hole distance of 5 mm between them), and converging and diverging angles (α and β = 10°, 15°, 20° and 25°). Multiple non-linear regression equations were also developed from the linear relation with the dependent variable (Non-dimensional form of standard aeration efficiency, NDSAE) and independent variables (tl and N). With the geometrically optimized venturi aerator the optimum performance was found for tl =100 mm, N = 17, and α and β = 15°. The maximum value of standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) obtained was 0.0216 kgO2/h and 0.611 kgO2/kWh respectively. From the non-dimensional study, it was found that the NDSAE is the function Reynolds number (Re) and Froude number (Fr). The simulation equations were developed on the basis of Re and Fr for NDSAE, and subjected to 7.378 × 10−6 <Re < 3.689 × 10-5 and 0.163 <Fr < 0.817, respectively.

Development of an electrode system for continuous measurement of the volume of an AHV

Mechanical circulatory assistance devices are vital for the patients with end-stage heart failure, who require heart transplantation but are in a waiting list due to the shortage of donor organs. This makes the development of the advanced MCS devices and artificial heart ventricles a crucial task. The systems for the dynamic and adaptive control of circulation parameters are required. AHV liquid volume measurement units must be developed to create such systems. Objective – Determination of the optimal electrode system for the AHV liquid volume measurement unit based on the electrical impedance measurements. The most significant geometrical parameters of the electrode systems for the impedance based AHV liquid volume measurement are determined. The optimal values of the geometrical parameters were found for the system of dynamic AHV liquid volume measurement. Results were confirmed by the numerical and experimental studies. The obtained values of the optimal geometrical parameters of electrode systems will be used in development of biotechnical system of adaptive AHV control.

Estimation of natural streams longitudinal dispersion coefficient using hybrid evolutionary machine learning model

Among several indicators for river engineering sustainability, the longitudinal dispersion coefficient () is the main parameter that defines the transport of pollutants in natural streams. Accurate estimation of has been challenging for hydrologists due to the high stochasticity and non-linearity of this hydraulic-environmental parameter. This study presents a new hybrid machine learning (ML) model integrating a Gaussian Process Regression (GPR) and an evolutionary feature selection (FS) approach (i.e. Covariance Matrix Adaptation Evolution Strategy (CMAES)) to estimate in natural streams. The dataset consists of geometric and hydraulic river system parameters from 29 streams in the United States. The modeling results showed that the proposed model outperformed other models in the literature, producing more stable and accurate estimations. The FS approach evidenced the significance of the cross-sectional average flow velocity (U), channel width (B), and channel sinuosity σ to estimate the dispersion coefficient. In quantitative terms, the integrated GPR model with feature selection approach attained the minimum root mean square error () and maximum coefficient of determination (). The proposed hybrid evolutionary ML model arises as robust, flexible and reliable alternative computer aid technology for predicting the longitudinal dispersion coefficient in natural streams.

Optimal design parameters of air suspension systems for semi-trailer truck. Part 1: modeling and algorithm

The purpose of this paper is to improve the performance of air suspension systems for a semi-trailer truck in the direction of reducing the dynamic wheel load acting on road surface (Part 1: modeling and algorithm). To achieve the goal of finding the optimal design parameters for the air suspension systems, a half-vehicle dynamic model under the road-vehicle interaction with 12 degrees of freedom (d.o.f) is established for searching the optimal design parameters of vehicle suspensions using genetic algorithm (GA). Dynamic load coefficient (DLC) is considered as a target function. Two optimal conditions: optimal design of geometrical parameters of air spring suspension systems (Case 1) and optimal design of parameters of air suspension systems (Case 2) are selected in this study. The results of this paper are the basis for optimization and discussion in Part 2 as the results and discussion.

Influence of geometric and physical Windbelt system parameters on instability pattern

Windbelt system non-linear aeroelastic vibrations are considered. In particular, how the various physical and geometric system parameters (overall dimensions, density of the air and ribbon material, internal damping) affects on the incoming air flow critical velocity value and the system’s supercritical nature of the behaviour.

Scale effect in a fluid-conducting fault network

The data presented in the article consistently outlines the methodology for studying the orientation and morphogenetic characteristics of fracture systems of four scale levels including kilometers, meters, centimeters and millimeters. The Urtuisky granite massif, located in the South-Eastern Transbaikalia to the west of the Streltsovsky caldera, containing uranium deposits unique in their reserves was chosen as the object of the research. The massif is composed of Late Riphean granites and granite-gneisses, affected by dynamometamorphic and hydrothermal-metasomatic transformations in various degrees, and dissected by numerous faults with traces of fluid activity of various tectogenesis episodes. The interrelation between such geometrical parameters of fractures systems as specific density and specific length was established. It is shown that such geostructural data should be used for conceptual and numerical modeling of fluid filtration and radionuclides transport processes occurring in a three-dimensional fractured-pore space of crystalline rocks, as applied to the reconstruction and modeling of uranium ore formation and use of geological space for radioactive materials isolation.

Scale Effect in a Fluid-Conducting Fault Network

The data presented in the article consistently outlines the methodology for studying the orientation and morphogenetic characteristics of fracture systems of four scale levels including kilometers, meters, centimeters and millimeters. The Urtuisky granite massif, located in the South-Eastern Transbaikalia to the west of the Streltsovsky caldera, containing uranium deposits unique in their reserves was chosen as the object of the research. The massif is composed of Late Riphean granites and granite-gneisses, affected by dynamometamorphic and hydrothermal-metasomatic transformations in various degrees, and dissected by numerous faults with traces of fluid activity of various tectogenesis episodes. The interrelation between such geometrical parameters of fractures systems as specific density and specific length was established. It is shown that such geostructural data should be used for conceptual and numerical modeling of fluid filtration and radionuclides transport processes occurring in a three-dimensional fractured-pore space of crystalline rocks, as applied to the reconstruction and modeling of uranium ore formation and use of geological space for radioactive materials isolation.

STUDY OF DEFORMATION AND STRESS STATE OF OVERHEAD PIPELINES ON THE PERMAFROST SOILS

Background The development of the fuel and energy complex of Russia causes the necessity of construction of overhead pipelines in the areas of permafrost prevalence in the Arctic and near-Arctic latitudes. This implies implementation of detailed analysis of the factors that ensure the operational reliability of pipeline systems and environmental safety of the environment, which are not sufficiently explored today. The main factors for ensuring the reliability of pipeline systems are optimal design solutions, reasonable calculation methods and rational installation schemes. This work is devoted to the first two factors. Aims and Objectives Scientific substantiation of the program calculation method of overhead pipelines and determination of optimal design solutions at their construction on permafrost soils. Methods At this stage, the following methods of research were used: analysis, generalization and modeling (by means of the universal software system of finite element analysis - ANSYS). Results There are received dependencies of transverse displacements and maximal stresses, arising in the overhead pipeline at self-compensation of deformations from geometrical parameters of system and constant of friction on supports.

Analysis of the Super‐Resolution Effect on Microwave Tomography

AbstractThis study investigates the spatial resolution (SR) and super‐resolution effect in microwave tomography in terms of single‐frequency measured data. The applied method is based on our recently proposed concept of average SR (ASR). We apply truncated singular value decomposition to calculate a regularized forward‐modeling matrix and to limit the truncation index by the acceptable level of the imaging noise. A simple relation of the ASR with the truncation index calculates the ASR in the imaging zone. The described method to calculate SR is quite common, and it considers not only the geometrical parameters of the microwave tomography system and object under test but also the noise in the measured data. This method is applicable to the linear and nonlinear considerations of the inverse scattering problem with respect to two‐ or three‐dimensional solutions. In particular, our investigation confirms the conclusion of some other authors that applying nonlinear inverse scattering methods can achieve the super‐resolution imaging even when based on far‐field measured signals only.

Design optimization of a thrust chamber using a mass-based model to improve the geometrical and performance parameters of low-thrust space propulsion systems

A large portion of the wet and dry mass budget in any space system is assigned to the propulsion system. Each of these depends on the engine system design values. Any effort to decrease the mass of space systems demands an additional effort to reduce the propulsion system mass, which in turn requires a complete review of the engine design. Thus, proposing a computational model derived from the engine design and based on minimum system mass is necessary. The present computational research developed a propulsion system design strategy for liquid propulsion systems to optimize take-off mass and satisfy the thrust required under performance and structural constraints. Improvement of the geometric and performance variables and component mass using a mass-based model for optimization process is investigated. The method uses a hybrid genetic algorithm sequential quadratic programming as an optimizer. The mass-based formulation problem is solved using a hybrid optimization algorithm with a genetic algorithm as the global optimizer and sequential quadratic programming as the local optimizer starting from the solution given by the genetic algorithm. The convergence of the optimization algorithm is improved by introducing an initial solution based on genetic algorithm. Comparison of the proposed design optimization model with a real space propulsion system indicates that the performance of the proposed algorithm significantly improved the final results. While propellant mass, engine consumption rate and engine geometric dimensions decreased, specific impulse increased. All of these decreased the total mass of the space propulsion system.