Values Of System Parameters Research Articles

Energy Simulation and Parametric Analysis of Water Cooled Thermal Photovoltaic Systems: Energy and Exergy Analysis of Photovoltaic Systems

It is generally agreed that solar energy, which can be converted into usable electricity by means of solar panels, is one of the most important renewable energy sources. An energy and exergy study of these panels is the first step in developing this technology. This will provide a fair standard by which solar panel efficiency can be evaluated. In this study, the MATLAB tool was used to find the answers to the math problems that describe this system. The system’s efficiency has been calculated using the modeled data created in MATLAB. When solving equations, the initial value of the independent system parameters is fed into the computer in accordance with the algorithm of the program. A simulation and a parametric analysis of a thermal PV system with a sheet and spiral tube configuration have been completed. Simulations based on a numerical model have been run to determine where precisely the sheet and helical tubes should be placed in a PV/T system configured for cold water. Since then, the MATLAB code for the proposed model has been developed, and it agrees well with the experimental data. There is an RMSE of 0.94 for this model. The results indicate that the modeled sample achieves a thermal efficiency of between 43% and 52% and an electrical efficiency of between 11% and 11.5%.

Recurrence quantification and bifurcation analysis of electrical activity in resistive/memristive synapse coupled Fitzhugh–Nagumo type neurons

Temporal response of excitable individual and coupled different neuronal circuits i.e., Cell-I and Cell-II, of Fitzhugh–Nagumo type have been numerically simulated with a view to understand and characterize the complexities of involved dynamical processes. FHN neuronal circuit Cell-I and Cell-II have been shown to exhibit supercritical Hopf bifurcation, when excited by an external steady stimulus. For time varying sinusoidal excitation, the temporal action potential behavior of these neuronal circuits, when analyzed using measures of recurrence quantification analysis (RQA) and bifurcation diagram reveals period-1, period-2, multi-periodic, chaotic and reverse period doubling characteristics as observed earlier experimentally in giant squid axon and other biological cell assemblies. Phase portrait, bifurcation diagrams and recurrence plot (RPs), of (i) unidirectional and (ii) bidirectional coupled FHN Cell-I and Cell-II, through a gap junction resistor, suggest the possibility of transition to intermittent state besides the transition of respective action potential from periodic to multi-periodic to chaotic state in an ordered or disordered fashion, depending on values of system parameters that control the complexities. Further, for both the configurations (i) and (ii), synchronization of FHN neuron Cell-I with Cell-II is also shown to occur for large values of coupling parameter, ξ. The dynamical effect of electromagnetic radiation on individual FHN neuron circuits has also been investigated using a flux controlled memristor that couples the magnetic flux with the individual FHN neurons. Phase portrait, bifurcation and RQA analysis have also been used to characterize the electrical activities of excitable cell assemblies involving memristive synapse coupled FHN neuronal Cell-I and Cell-II in settings (i) and (ii) respectively.

Multiobjective Design Optimization of Extremely Low-Frequency Power Amplifier Considering Accuracy, Volume, and Reliability

The extremely low-frequency power amplifier (ELFPA) used in the communication system is required to have high output accuracy, small size, and high reliability under complex mission profiles simultaneously. However, the system parameters that determine these performances are coupled with each other, and it is difficult to directly select the optimal solution that meets all output performances at the same time. Thus, a new high reliable parameters design method is proposed for ELFPA system, which can simultaneously consider the relationship among multiple mutually coupled, nonlinear control variables and output performances. Moreover, the multiobjective particle swarm optimization (MOPSO) algorithm is used to search for the Pareto-optimal solutions and the best design. The use of this optimization algorithm aims to avoid the empirical trial-and-error method for adjusting the parameter values and quickly find the system parameter value that best trades off the total harmonic distortion (THD), volume, and lifetime of the system. To illustrate the superiority of the proposed approach, the proposed parameter design process of a 5-kW power amplifier is verified by both simulation and experimental results.

Queuing Analysis of QoS Aware Microwave Power Transfer Enabled CR-IoT Network

We analyze a Cognitive Radio-based Internet-of-Things (CR-IoT) network employing Microwave Power Transfer (MPT) method for energy-harvesting, targeted for smart city applications. In our model, multiple IoT sensors, operated by an IoT operator, coexist with a Primary Network Provider (PNP), where the IoT sensors opportunistically exploit the spectrum holes in the PNP’s licensed band. We develop an Imbedded Markov Chain based approach to analyze this system. During PNP’s inactivity periods, the Accesss Points (APs) under the IoT operator have to judiciously use PNP’s licensed band for data collection from the IoT sensors and charging them via the MPT method. Our analysis finds the balance between these activities while maintaining the Quality-of-Service and preventing energy deficit in the IoT sensors. We characterize PNP’s activity using any distribution, rather than exponential distribution used in literature, making our framework more accurate. We also consider the possibility of interruptions in the IoT operator’s activity due to PNP’s transmission, which has been overlooked in the literature. Extensive simulations demonstrate the accuracy of our analysis. Our analysis can identify the values of system parameters that makes the system sustainable. We have also shown how to extend our model to accommodate multiple PNPs in the same CR-IoT network.

Synchronization of Gursey System

Gursey Model, the only possible four-dimensional pure spinor model, proposed as a possible basis for a unitary description of elementary particles. The model exhibits chaotic behaviors depending on the system parameter values. In this study, we investigate the synchronization of chaotic dynamic in the Gursey wave equation that has particle-like solutions derived classical field equations. Numerical results for synchronization of the Gursey system are performed to indicate the accuracy of the used method.

Mathematical Modeling of Efficiency Evaluation of Double-Pass Parallel Flow Solar Air Heater

To investigate the influencing range and optimize values of different operational and system parameters on the double-pass parallel flow solar air heater’s (DPPFSAH) thermal, effective, and exergetic efficiencies, an iterative method was used to analyze the governing energy equations using a theoretical model written in MATLAB based on the Nusselt number (Nu) and friction factor (f) correlations developed in the work performed earlier. A comparison between double-pass and single-pass SAHs for mathematical and experimental outcomes was conducted, and the results were found to be fairly consistent. According to the thermo-hydraulic performance indicators, similar to single-pass SAHs, perforated multi-V rib-roughened DPPFSAHs achieve optimum thermal performance for lower Reynolds numbers, which does not change much as the Reynolds number increases above 18,000. This finding can be taken into account when designing any DPPFSAH.

Supratransmission-induced traveling breathers in long Josephson junctions

The emergence of traveling sine-Gordon breathers due to the nonlinear supratransmission effect is theoretically studied in a long Josephson junction driven by suitable magnetic pulses, taking into account the presence of dissipation, a current bias, and a thermal noise source. The simulations clearly indicate that, depending on the pulse’s shape and the values of the main system parameters, such a configuration can effectively yield breather excitations only. Furthermore, a nonmonotonic behavior of the breather-only generation probability is observed as a function of the noise intensity. Finally, the dynamics of the supratransmission-induced breathers is characterized by looking at quantities such as their radiative decay lifetime and the medium’s energy.

Finding Optimal Parameter Values for the MACD Indicator: Evidence From the Japanese Nikkei 225 Futures Market Using a New Methodology

This paper explores: (1) what parameter values are most often used to optimize the Moving Average Convergence Divergence (MACD) trading system for the Japanese Nikkei 225 futures market; and, (2) the characteristics of good-performing models with the optimized parameter values. To accomplish this purpose, this paper presents a new methodology to find the three optimal parameter values of the MACD trading system; this approach systematically examines specific ranges of optimal parameter values. Evidence from the Japanese futures market demonstrates the validity of this new methodological approach. From this, we find that for the Japanese market the technical trading system is most often optimized by three parameter values within three specific ranges over the last 11 years (2011–2021). These optimal value combinations have a unique characteristic form. These findings give insightful and broader perspectives about the market. This issue, methodology and the results have not been discussed in the existing literature. This paper also considers how the models with optimal parameter values performed during the pandemic period (2020–2021).

Regulating dynamics through intermittent interactions.

In this article we experimentally demonstrate an efficient scheme to regulate the behavior of coupled nonlinear oscillators through dynamic control of their interaction. It is observed that introducing intermittency in the interaction term as a function of time or the system state predictably alters the dynamics of the constituent oscillators. Choosing the nature of the interaction, attractive or repulsive, allows for either suppression of oscillations or stimulation of activity. Two parameters Δ and τ, that reign the extent of interaction among subsystems, are introduced. They serve as a harness to access the entire range of possible behaviors from fixed points to chaos. For fixed values of system parameters and coupling strength, changing Δ and τ offers fine control over the dynamics of coupled subsystems. We show this experimentally using coupled Chua's circuits and elucidate their behavior for a range of coupling parameters through detailed numerical simulations.

Effect of High Frequency Gain on the Performance of Optical Costas Loop in Face of Loop Delay

Objectives: Optical costas loops (OCLs) are widely used in optical communication as homodyne receivers. Due to use of different electronic counterparts and fibre optic cable inherent loop delay always presents in the system. The steady state behaviours of optical costas loop are highly affected by the presence of loop delay. Different nonlinear behaviours may be observed due to presence of delay. There are two main objectives of this article. Firstly, how OCL can be operated as stable receiver up to some large value of loop delay by using a proportional plus integrating type loop filter (LF). Secondly, how a controlled chaotic optical signal can be generated from OCL by choosing the system parameters in correct manner. Methods: To investigate system behaviours of OCL both analytical and numerical methods have been used. Stability analysis of OCL has been done by Routh-Hurwitz method. From stability analysis, it is possible to predict the stable and unstable behaviour of the OCL in presence of delay and how system stability can be improved by high frequency gain value of LF. Numerical methods have also been used to solve the nonlinear equation of OCL to observe real time behaviours. Findings: Analytical findings show that loop stability can be improved by increasing the value of high frequency gain of LF. For large value of loop delay, chaotic oscillation of phase error may be observed in OCL. The chaotic oscillation can also be controlled by high frequency gain with certain extent value of loop delay. All the numerical findings have been properly verified with numerical results. Novelty: This article describes how effects of loop delay can be controlled to run OCL in steady as well as in unsteady state. From designer’s point of view this study would be helpful to choose correct values of system parameters to improve the performance of OCL in optical communication. It also gives the idea for generation of chaotic optical signal, which is used in secured communications. Keywords: Optical Costas loop; Optical Phase locked loop Phase detector; Loop filter; Nonlinear dynamics; and optical communications

Qualitative analysis, chaos and coexisting attractors in an asymmetric four-well ϕ 8 -generalized Liénard oscillator driven by parametric and external excitations

In this paper, we study the qualitative dynamical analysis, routes to chaos and the coexistence of attractors in a four-well \(\phi^8\)-generalized Liénard oscillator under external and parametric excitations. The local analysis of the autonomous system reveals saddles, nodes, spirals or centers for appropriate choice of stiffness and damping coefficients. The existence of a Hopf bifurcation is proved during the stability analysis of the equilibrium points. The routes to chaos and the prediction of coexisting attractors have been investigated numerically by using the fourth order Runge-Kutta algorithm. The bifurcation structures obtained show that the system displays a rich variety of bifurcation phenomena, such as symmetry breaking, symmetry restoring, period-doubling, period windows, period-m bubbles, reverse period windows, antimonotonicity, intermittency, quasiperiodic, and chaos. In addition, remerging chaotic band attractors and remarkable routes to chaos occur in the system. Further, it is found that the system presents various coexistence of two attractors as well as the monostability and bistability phenomena. On the other hand, for large amplitude of the parametric excitation and with \(\omega = 1\), the coexistence of asymmetric periodic bursting oscillations of different topologies takes place in the system. It has also been shown numerically that for appropriate values of system parameters and initial conditions, the presented system can exhibit up to five types of coexisting multiple attractors.

Contrasts in 2-D and 3-D system behaviour in the modelling of compositionally originating LLSVPs and a mantle featuring dynamically obtained plates

SUMMARY More than two decades of systematic investigation has made steady progress towards generating plate-like surface behaviour in models of vigorous mantle convection. Accordingly, properties required to obtain dynamic plates from mantle convection have become widely recognized and used in both 2-D and 3-D geometries. Improving our understanding of the properties required to obtain durable (or replenishable) deep mantle features with LLSVP-like characteristics has received interest for a period with similar longevity. Investigation ultimately focuses on discovering the properties able to produce the presence of a detached pair of 3-D features, distinct from the ambient mantle. Here, we assume the large low shear-wave velocity provinces (LLSVPs) have a chemical origin by incorporating a compositionally anomalous and intrinsically dense (CAID) mantle component comprising 2–3.5 per cent of the total mantle volume. The feedback between plate formation and the presence of a CAID mantle component is investigated in both 2-D and 3-D spherical geometries. We explore the impact of both an intrinsic contrast in density and viscosity for the CAID component, with the objective of finding system parameter values that encourage the formation of a pair of LLSVP-like assemblages and a surface that exhibits the principle features of terrestrial plate tectonics; including recognizable and narrowly focused divergent, convergent and (in 3-D) transform plate boundaries that separate 8–16 distinct plate interiors. We present the results of nine 2-D and 11 3-D calculations and show that for some of the cases examined, a pair of CAID material provinces can be freely obtained in 2-D cases while maintaining a surface characterized by plate-like behaviour. However, specifying the same system parameters in the 3-D model does not readily yield a pair of enduring provinces for any values of the parameters investigated. Moreover, the inclusion of the CAID component in the mantle can affect the global geotherm so that in comparison to the surface behaviour obtained for the initial condition isochemical model, the surface behaviour of the cases incorporating the dense component are less exemplary of plate tectonics. In general, CAID material components that are 3.75–5 per cent denser than the surrounding mantle (at surface temperatures), and up to a factor of 100 times greater in intrinsic viscosity, form layers populated by voids, or nodes connected by tendril-like ridges that reach across the core–mantle boundary (CMB), rather than distinct piles resembling LLSVPs. Due to its inherently heavy and stiff character, in equilibrated systems, we find the CAID material becomes especially hot so that the temperature-dependence of its density and viscosity results in reduced distinction between the intrinsically dense assemblages and the ambient mantle. Accordingly, the CAID material forms masses on the CMB that are relatively less dense (0.625–1.5 per cent) and viscous than the adjacent mantle material, in comparison to the percentage differences obtained at common temperatures. We find that by adjusting our yield stress model to account for the influence of the CAID material on the geotherm, a highly satisfactory plate-like surface can be re-attained, however, the formation of a pair of LLSVP-shaped masses remains elusive.

Model-Based Systems Engineering Tool-Chain for Automated Parameter Value Selection

Cyber-physical systems (CPSs) integrate heterogeneous systems and process sensor data using digital services. As the complexity of CPS increases, it becomes more challenging to efficiently formalize the integrated multidomain views with flexible automated verification across the entire lifecycle. This article illustrates a model-based systems engineering tool-chain to support CPS development with an emphasis on automated parameter value selection for co-simulation. First, a domain-specific modeling approach is introduced to support the formalizations of CPS artifacts, development processes, and simulation configurations. The domain-specific models are used as the basis to generate a Web-based process management system for automated parameter value selections, which coordinates Open Services for Lifecycle Collaboration services of development information and technical resources (models, data, and tools) in order to support automated co-simulation. The services are deployed by a service orchestrator based on a decision-making algorithm for parameter value selection. Finally, developers make use of the WPMS to implement simulations and to select system parameter values for co-simulation automatically. The approach is illustrated by a case study on auto-braking system development and we evaluate the efficiency of this tool-chain by both qualitative and quantitative methods. The results show that parameter values are selected more efficiently and effectively when implementing co-simulations using our tool-chain.

Investigation and Optimization of MQL System Parameters in the Roller-Burnishing Process of Hardened Steel

In the current study, the internal burnishing process under the minimum quantity lubrication (MQL) condition has been optimized to decrease the cylindricity (CYL) and circularity (CIC) of the burnished hole, while the surface roughness (SR) is predefined as a constraint. The optimizing inputs are the diameter of the spray nozzle (D), the spray elevation angle (A), the lubricant quantity (Q), and the pressure value of the compressed air (P). The artificial neural network (ANN) models of burnishing performances are proposed to optimise inputs. The grey relational analysis (GRA) is utilized to compute the weight value of each response. Optimal values of MQL system parameters and technological objectives are selected with the aid of an evolution algorithm (vibration and communication particle swarm optimization (VCPSO) algorithm). The results indicated that the optimal outcomes of the D, A, Q, and P are 1.5 mm, 50 deg, 140 ml/h, and 0.6 MPa, respectively. Furthermore, the CYL, CIC, and SR were decreased by 53.14 %, 57.83 %, and 72.97 %, respectively, at the optimal solution. Finally, the obtained results are expected to be a significant solution to support the machine operator in selecting the optimal MQL system parameters to improve the hole quality in the MQL-assisted burnishing process.

Modeling and Dynamic Analysis for a Motion of Mounted-Based Axisymmetric Rigid Body under Self-Excited Vibrations in an Attractive Newtonian Field

In this article, the mathematical modeling and dynamic analysis for a motion of a rigid body mounted on a vibrating base affected by a strongly nonlinear damping and an attractive Newtonian field are investigated. The governing equations are derived, and specific conditions for asymptotic stability of the motion are stated. Results of analytical analysis are used to identify some distinct types of motion, including the cases that are apparently regular or chaotic. A reduction technique via averaging is used to obtain the amplitude equation and the response diagrams to identify regions where the jump phenomenon may occur. Moreover, a simple analytical relationship between the parameters of the system, describing whether the jump phenomenon will be possible, is obtained. Homoclinic bifurcation diagrams are used to argue apparently that the chaotic behavior is slowly approaching a strange attractor at specific values of system parameters. Results of numerical solutions using the fourth-order Runge-Kutta method are closely coincided with the analytical ones to verify all types of motion.

Opportunities and Challenges for Long-Distance Transmission in Hollow-Core Fibres

The loss of hollow-core Nested Antiresonant Nodeless Fiber (NANF) has been steadily decreasing lately, approaching that of standard Single-Mode Fiber (SMF). As for non-linear effects, they are already three to four orders of magnitude lower than in SMF. Theoretical predictions and experimental evidence also hint at a much wider usable bandwidth than SMF, potentially several tens of THz. Propagation speed is 50%faster, a key feature in certain contexts. We investigate the potential impact of possible future high-performance NANF on optical communication systems, assuming that NANF continues on its current path towards better performance. We look at system throughput in different scenarios, addressing links from 100 km to 4,000 km, assuming different NANF optical bandwidths and loss. We found that NANF might enable throughput gains, vs. a benchmark SMF Raman-amplified C+L system, on the order of 1.5x to 5x, at reasonable system parameter values, including launch power. We also consider NANF Inter-Modal-Interference (IMI) and show that the value required for negligible system impact is about –60 dB/km, close to the currently best reported values. We finally look at more long-term scenarios in which NANF loss might get below that of SMF and we show that in this context repeaterless or even completely amplifierless systems might be possible, delivering 300400 Tb/s per NANF, over 200 to 300 km distances. While several technological hurdles remain before NANF systems become practical, NANF appears to have the potential to become an attractive and possibly disruptive alternative to conventional solid-core silica fibers.

Behavior of quantum discord, local quantum uncertainty, and local quantum Fisher information in two-spin-1/2 Heisenberg chain with DM and KSEA interactions

A two-qubit Heisenberg XYZ model with Dzyaloshinsky–Moriya (DM) and Kaplan–Shekhtman–Entin-Wohlman–Aharony (KSEA) interactions is considered at thermal equilibrium. Analytical formulas are derived for the local quantum uncertainty (LQU) and local quantum Fisher information (LQFI). Using the available expressions for the entropic quantum discord, we perform a comparative study of these measures of nonclassical correlation. Our analysis showed the following: all three measures of quantum correlation have similar qualitative and even quantitative behavior on temperature for different values of system parameters, there are regions in the parameter space correspondent to a local increase of correlations with increasing temperature, and sudden changes in the behavior of quantum correlations occur at certain values of the interaction parameters.

Seasonal adaptation of VRF HVAC model calibration process to a mediterranean climate

Today, Building Energy Models (BEM) have become essential in regulatory compliance calculations, the correct assessment of it’s Air Conditioning (AC) systems is critical for the reduction of the performance gap between BEMs and reality and increase the accuracy of evaluating buildings energy performance and it’s systems efficiency. Given that multi-split Variable Refrigerant Flow (VRF) systems have grown in the market in recent years becoming a particular trending solution to achieve building indoor comfort; the present paper focus on technical issues when modelling such VRF systems inside EnergyPlus, a white-box simulation environment, especially regarding the effects weather conditions have on the behaviour of VRF systems and it’s correlation with the AC system performance curves. The study performs an empirical validation of an optimization-based calibration methodology assessing multiple levels: average interior temperature of the different building spaces and electric energy consumption from VRF outdoor unit. It is performed using fifteen minute time-step seasonal data obtained from a fully operational building located in a typical Mediterranean climate (Greece), adjusting the parameter and curve values of the VRF system using a genetic NGSA-II algorithm (Jeplus software) for both summer and winter conditions. The generated BEM captures the building’s hourly performance for summer conditions using 1717 hours to fit into international standards. Complying with the requirements of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Guidelines 14-2002 for hourly energy consumption, reaching an NMBE ⩽±10% ,Cv(RMSE) ⩽30% and R2 ⩾75% while keeping indoor temperatures on every room with a RMSE ⩽1 °C. The resulting BEM proved stable during the 2077 hours of it’s summer evaluation period, fitting into the new unseen weather and building operation conditions of 2020 which can be considered a step forward in the area of calibrating white box models. While for winter conditions the study demonstrates the value of the calibration methodology while presenting the importance of weather influence on VRF systems. Using a total of 802 hours the applied technology greatly improves the results from the baseline model, reaching a partially calibrated BEM model for winter. Which reinforces the fact that regardless of how good a baseline model is, building operating conditions and weather may will always generate a design/performance gap and therefore the calibration of a BEM is unavoidable.

Conditions for realizing one-point interactions from a multi-layer structure model

A heterostructure composed of N parallel homogeneous layers is studied in the limit as their widths l 1, …, l N shrink to zero. The problem is investigated in one dimension and the piecewise constant potential in the Schrödinger equation is given by the strengths V 1, …, V N as functions of l 1, …, l N , respectively. The key point is the derivation of the conditions on the functions V 1(l 1), …, V N (l N ) for realizing a family of one-point interactions as l 1, …, l N tend to zero along available paths in the N-dimensional space. The existence of equations for a squeezed structure, the solution of which determines the system parameter values, under which the non-zero tunneling of quantum particles through a multi-layer structure occurs, is shown to exist and depend on the paths. This tunneling appears as a result of an appropriate cancellation of divergences.

Content-adaptive image compression and encryption via optimized compressive sensing with double random phase encoding driven by chaos

With the advancement of multimedia technology and coming of big data era, the size of image data is significantly increased. However, the traditional image encryption methods cannot solve the emerging problems of efficient compression. To settle with this challenge, an effective content-adaptive image compression and encryption method based on compressive sensing and double random phase encoding (DRPE) is proposed in this paper. The original image is converted to one low-frequency part and three high-frequency parts by DWT and then permutated by sorting-based chaotic sequences. Afterward, a novel measurement matrix optimization algorithm based on adaptive step size is presented to measure the high-frequency components. To enhance the security of the scheme, the DRPE, quantization, and diffusion are successively performed on the complex matrix composed of the shuffled low-frequency component and three measurement value matrices to obtain the cipher image. Logistic-Sine chaotic system is utilized to produce the chaotic keystreams for the encryption process, and its system parameter and initial value are determined by the information entropy of the plain image and external key parameters, so that the proposed cipher can withstand known-plaintext and chosen-plaintext attacks effectively. Numerical experiments demonstrate the effectiveness of the proposed image compression and encryption algorithm.