Parameters Of Weighting Functions Research Articles

Impact of Weight Functions on Performance of Three-Input Integrated Dc-Dc Converter in H ∞ Control

Many power electronic systems applications namely locomotives, hybrid electric vehicles, and all renewable energy sourced systems are shifting towards Multi-Input Multi-Output (MIMO) integrated DC-DC converters due to their reliability and flexible nature. Designing controllers for MIMO integrated DC-DC converter is complicated due to its integrated structure, presence of common elements, and interactions between the input and output variables of the converter. In this work, a Three-Input Integrated DC-DC (TIID) converter is modeled using state-space analysis, and a Transfer Function Matrix (TFM) is acquired from the small signal continuous time model. A robust controller based on the loop shaping method is designed for the TIID converter. In this loop-shaping method, the desired robustness and the performance of the controller are represented with weight functions i.e., loop-shaping filters. These weight functions are designed using TFM and are frequency-dependent. The robustness of the controller depends on the weight function parameters. The effect of varying the parameters of the weight functions on system dynamics, robustness, and performance are studied and plotted. TIID converter of 288 W, 24V-30V-36V to 48 V is considered and the impact of weight function on closed-loop system dynamics and sensitivity characteristics under varying parameter conditions are analyzed in MATLAB Environment.

Robust multimodel control for uncertain nonlinear MIMO systems based on ARX-Laguerre multimodel and LSDP approach

In this paper, we propose a new alternative for the robust control of nonlinear MIMO (multiple-input multiple-output) systems based on the multimodel approach and LSDP (Loop-Shaping Design Procedure)approach in the discrete case. First, the multimodel approach is exploited by representing each linear sub-model in the form of the recent linear MIMO ARX (Auto-Regressive with eXogenous inputs) -Laguerre model which guarantees a significant parameters number reduction compared with the MIMO ARX model. Thus, the resulting multivariable multimodel, entitled MIMO ARX-Laguerre multimodel, ensures a reduction of the parametric complexity with a simple recursive vector representation. However, this reduction is conditioned by an optimal choice of the pole characterising each Laguerre base. To deal with this, we propose the identification, using the genetic algorithm, of the Laguerre poles as well as the weighting function parameters of the MIMO ARX-Laguerre multimodel. This latter allows to generate a set of linear MIMO ARX-Laguerre sub-models which are exploited to propose a robust multimodel control for uncertain nonlinear MIMO systems. In fact, for each identified sub-model, we combine the LSDP approach and the RGA (Relative Gain Array) theory to develop a local robust controller. Then, a multivariable roust multimodel control algorithm is developed where the overall control strategy by multimodel approach amounts to incorporating the same weighting functions used in the considered multivariable multimodel in order to interpolate the control laws calculated from each local robust controller. The optimisation of Laguerre poles and weighting functions parameters as well as the proposed multivariable robust multimodel control algorithm are validated on the experimental prototype Quanser Aero system.

H∞ loop-shaping of a multi-input dc-dc converter using weight function parameter optimization

Designing of controllers for Multi-Input DC-DC Converter (MIDDC) topology is a challenging task due to control loop interactions. Most of the closed loop controllers designed for MIDDC topologies are by considering the interactions measures of the closed loops. In this article a non-isolated MIDDC converter with a compact structure is chosen and designing of robust controller using Loop Shaping Design (HILSD) methodology and is interaction independent. Stabilizing controller design require the selection of the weight function parameters, if the selection of weight function parameters is not chosen properly in designing of controller it may not achieve reasonable compromise between robust performance and robust stability. So, for better the design efficacy of HILSD, a weight function optimization problem is formulated where, Frequency Integral Square Error (FISE) based performance index is used as objective function, however the performance level of the designed controller which regulates MIDDC converter system and success of loop-shaping procedure are used as constraints. Global search algorithm has been used in this work to find the global optimum weight function parameters and these are obtained in MATLAB environment. Effectiveness of MIDDC converter is verified viz. simulation in PSIM environment with HILSD controller for the regulation of load voltage as well as load division by considering a 100 W, 36 V/12 V to 24 V dc power converter.

Viro-Immunological, Clinical Outcomes and Costs of Switching to BIC/TAF/FTC in a Cohort of People Living with HIV: A 48-Week Prospective Analysis.

To date, therapeutic switches are performed to reduce and prevent toxicity, improve adherence, promote virological control, and save costs. Drug switches are a daily challenge in the management of people living with HIV (PLWH), especially in those with multiple comorbidities and on polypharmacy. The objectives of this prospective analysis were: (I) to evaluate the viro-immunological efficacy of BIC/FTC/TAF in a cohort of PLWH who switched to this regimen from any other previous, at the Infectious and Tropical Diseases Unit of the Padua University Hospital; (II) to assess the impact on body weight, lipids, and renal function parameters at week 48; and (III) to evaluate daily costs changes, adherence, and the rate and causes of discontinuation of the regimen. We included all adult PLWH who switched to BIC/FTC/TAF from 1 February 2020 to 31 October 2021. We collected demographic, clinical, and laboratory data at baseline and week 48 after the switch. In addition, the estimated cART-related cost changes over the follow-up period were calculated. Over the study period, 290 individuals who switched to BIC/FTC/TAF, 76.9% were males, with a median age of 52 years, and 94.8% had an undetectable baseline HIV viremia. After a median time of 35 days (IQR: 1–55), 41 (14.1%) individuals discontinued the regimen. Factors significantly associated with discontinuation were switching from dual regimens, and neurological disorders. At week 48, we detected a significant increase in body weight, BMI, CD4 T-cell count, and CD4/CD8 ratio, and a significant reduction in triglycerides and costs; all patients had undetectable HIV RNA. Our results showed that switching to BIC/FTC/TAF may favor slightly immunological recovery and cost saving (−4.2 EUR/day from baseline to week 48, equivalent to a mean saving of 1533 EUR/year/person). The reduction in triglycerides does not appear to be clinically relevant, even if statistically significant, nor do both the increase in body weight and BMI (+1 kg and +0.29 BMI, respectively) and the increase in CD4 T-cell count (+45 cells/mmc). Further studies are needed to confirm our results.

Random attractors for stochastic discrete complex Ginzburg–Landau equations with long-range interactions

This paper is concerned with the pathwise dynamics of a class of stochastic discrete complex Ginzburg–Landau equations with long-range interactions. Under suitable assumptions on the weight function and coupling parameters of long-range interactions, we prove the existence and uniqueness of the random attractor for the considered system in weighted space.

Numerical integration in G/XFEM analysis of 2-D fracture mechanics problems for physically nonlinear material and cohesive crack propagation

PurposeThe aim of this paper is to present a novel data transfer technique to simulate, by G/XFEM, a cohesive crack propagation coupled with a smeared damage model. The efficiency of this technique is evaluated in terms of processing time, number of Newton–Raphson iterations and accuracy of structural response.Design/methodology/approachThe cohesive crack is represented by the G/XFEM enrichment strategy. The elements crossed by the crack are divided into triangular cells. The smeared crack model is used to describe the material behavior. In the nonlinear solution of the problem, state variables associated with the original numerical integration points need to be transferred to new points created with the triangular subdivision. A nonlocal strategy is tailored to transfer the scalar and tensor variables of the constitutive model. The performance of this technique is numerically evaluated.FindingsWhen compared with standard Gauss quadrature integration scheme, the proposed strategy may deliver a slightly superior computational efficiency in terms of processing time. The weighting function parameter used in the nonlocal transfer strategy plays an important role. The equilibrium state in the interactive-incremental solution process is not severely penalized and is readily recovered. The advantages of such proposed technique tend to be even more pronounced in more complex and finer meshes.Originality/valueThis work presents a novel data transfer technique based on the ideas of the nonlocal formulation of the state variables and specially tailored to the simulation of cohesive crack propagation in materials governed by the smeared crack constitutive model.

State of Health Prediction of Lithium-Ion Batteries Based on the Discharge Voltage and Temperature

Accurate state of health (SOH) prediction of lithium-ion batteries is essential for battery health management. In this paper, a novel method of predicting the SOH of lithium-ion batteries based on the voltage and temperature in the discharging process is proposed to achieve the accurate prediction. Both the equal voltage discharge time and the temperature change during the discharge process are regarded as health indicators (HIs), and then, the Pearson and Spearman relational analysis methods are applied to evaluate the relevance between HIs and SOH. On this basis, we modify the relevance vector machine (RVM) to a multiple kernel relevance vector machine (MKRVM) by combining Gaussian with sigmoid function to improve the accuracy of SOH prediction. The particle swarm optimization (PSO) is used to find the optimal weight and kernel function parameters of MKRVM. The aging data from NASA Ames Prognostics Center of Excellence are used to verify the effectiveness and accuracy of the proposed method in numerical simulations, whose results show that the MKRVM method has higher SOH prediction accuracy of lithium-ion batteries than the relevant methods.

Stationary Non-equilibrium Solutions for Coagulation Systems

We study coagulation equations under non-equilibrium conditions which are induced by the addition of a source term for small cluster sizes. We consider both discrete and continuous coagulation equations, and allow for a large class of coagulation rate kernels, with the main restriction being boundedness from above and below by certain weight functions. The weight functions depend on two power law parameters, and the assumptions cover, in particular, the commonly used free molecular and diffusion limited aggregation coagulation kernels. Our main result shows that the two weight function parameters already determine whether there exists a stationary solution under the presence of a source term. In particular, we find that the diffusive kernel allows for the existence of stationary solutions while there cannot be any such solutions for the free molecular kernel. The argument to prove the non-existence of solutions relies on a novel power law lower bound, valid in the appropriate parameter regime, for the decay of stationary solutions with a constant flux. We obtain optimal lower and upper estimates of the solutions for large cluster sizes, and prove that the solutions of the discrete model behave asymptotically as solutions of the continuous model.

A meshless regularized local boundary integral equation method and the selection of weight function and geometrical parameters

The local boundary integral equation (LBIE) method is a pure meshless integral method proposed by Atluri and co-workers. Since the fundamental solutions are used as the test functions, the sub-domain can be very small and the LBIE method is a promising method for solving problems of elasticity with nonhomogeneous material properties. In this paper, the subtraction technique is introduced to remove the strong singularity that results in a regularized local boundary integral equation (RLBIE) method. The formula is rather straightforward and more accurate than other treatment techniques. Compared with other meshless methods, more geometrical parameters need to be assigned in the method. If the parameters change a little bit, the solutions obtained from the method may fluctuate quickly and uncertainly. Therefore the effects of weight function, support domain, sub-domain, and monomial basis are investigated and how to select the parameters is discussed. The appropriate parameters can be determined and the meshless RLBIE method is an accurate and robust method.

A Stable and Reliable Short-Path Routing Scheme for Efficient Acoustic Wireless Sensor Networks (AWSNs)

Owning to the vital resources in a harsh and unforeseeable aqueous environment, the network stability and reliability in underwater acoustic wireless sensor networks (UAWSNs) have paramount significance. Stability guarantees the consistent performance of the network node's energy consumption, avoids data loss, packets reception time and network lifetime. The reliability of packet ensures the selection of favorable channel and avoid adverse channel effects, and the vital information is easily obtained from data packets. This paper introduces two new routing schemes for UAWSNs; stable and reliable short-path routing (RSPR) scheme, and cooperative reliable short-path routing (CoRSPR). In RSPR routing, the destination node is selected by considering the weighting function parameters of the highest residual energy, highest SNR, lowest euclidean distance, and least number of neighbor nodes. The scheme reduces the energy consumption due to less number of nodes contribution in the packet advancement process. The RSPR protocol is a non-cooperative technique, where the packets are delivered using a single-path link, which may not be consistently reliable. To cope with this issue, the CoRSPR protocol is proposed, which takes cooperative routing into account, for stable and reliable data delivery. In cooperative routing, the reception of more than one copy of the data packet is involved by the destination node. This reduces the unfavorable channel effects during data delivery. The simulation results show that the proposed schemes achieve better performance in terms of dead nodes, energy left in the battery, packet acceptance ratio, successful receiving of packets at the sink and E-2-E delay.

Acute and sub-acute toxicity of the crude extracts of the aerial parts of Daucus carota L. in laboratory rats

Background: Daucus carota L. belongs to the family Apiaceae and it is commonly known as carrot. The aerial part is used in some Northern parts of Nigeria as a livestock feed without scientific evidence of its safety to animal and man.Aim: The study assessed the safety margins of the D. carota aerial parts.Setting: The aerial part of D. carota were sourced from cultivated farmland at the outskirts of Samaru, Sabon Gari Local Government Area of Kaduna State and authenticated at Herbarium Unit of the Department of Botany, Ahmadu Bello University Zaria, Nigeria. The aerial parts were air-dried under shade, pulverised and stored properly for analysis.Methods: According to the Organization for Economic Cooperation and Development (OECD) method, the acute and sub-acute toxicity studies were carried on the crude extracts of the aerial parts to evaluate the safety of the healthy Wistar rats.Results: The findings from the oral acute toxicity study showed that there was no sign of toxicity and mortality at 5000 mg/kg in the n-hexane, ethyl acetate and methanol extracts. The sub-acute toxicity graded doses of 500 mg/kg, 1000 mg/kg and 1500 mg/kg of these extracts revealed a significant difference (p ≤ 0.05) on body weight, haematological parameters, liver and kidney function parameters. The histopathological effects of the extracts revealed different morphological alterations in the liver and kidney when compared with the control group.Conclusion: The study concluded that the aerial parts of D. carota might not be safe for livestock and its consumption could be capable of causing liver, kidney, tissue injury and other related diseases to animal and man.

Total Protein, Bilirubin and AST Levels in Rat Models Treated with Ethanolic Extract of Eleusine coracana during Arsenic Trioxide Induced Hepatotoxicity

Eleusine coracana is considered one of the most nutritious cereals. It has different names in local languages. It is known as Ragi in Telugu and Kannada/aariyam in Tamil, and Madua in Hindi and in Nigeria, it is known as Okababa in Yoruba, Dawa in Hausa, etc. This study sought to investigate the protective ability of ethanolic extracts of Eleusine coracana in Arsenic trioxide induced hepatotoxicity using rat models. Animals were grouped into four (4). Group A received only distilled water, in group B,C and D hepatotoxicity was induced using 5 mg/dl Arsenic Trioxide solution for 14 days, followed by treatment in group C and D daily with 200 mg and 500 mg per kg body weight respectively for 14 days, and changes in body weight and Liver Function parameters were determined. Eleusine coracana contains Tannins, phlobatannins,Falavonoids and Terpenoids but not Steriods and Saponins, Eleusine treated groups had a significant decrease in the organ-body weight index. The mean weight and Total Protein was significantly reduced in the intoxicated-untreated group (group B). The AST, direct and total Bilirubin level was significantly higher in group B compared to control and other treated groups. Eleusine cocarna as a plant and source of food contains certain phytochemicals which are capable of managing hepatic cell injury, this serve as a point for pharmacological intervention.

Wave Dispersion and Propagation in Linear Peridynamic Media

We detail the linear peridynamic wave equation with a nonlocal integral form based on the linear peridynamic and dynamic theory. Wave dispersion in an infinite maraging steel material is obtained by analyzing the linear peridynamic wave equation. The dispersion curves, group velocity, phase velocity, and other wave parameters of the shear and longitudinal waves in an infinite media are obtained using numerical methods. We obtained the optimal calculation parameters by analyzing the weight function, horizon, mesh size, and other numerical calculation parameters on the dispersion curve. We simulated the propagation of waves in an infinite media by applying these parameters into the peridynamic wave equation. We conclude that the wave model can generate waves that propagate in all directions with initial loads. The wavefront is an ellipsoid.

Improved co-optimal and evaluable index of carbon sequestration and enhanced oil recovery

To satisfy the requirements of the new technology of carbon capture, utilization, and storage (CCUS), it is recommended that carbon dioxide-enhanced oil recovery (CO2-EOR) projects change their design objective index by taking carbon sequestration into account, an approach that significantly differs from the traditional design. This study builds a new optimal index function for the new requirement based on the existing indices of the traditional index and the Kovscek index, which are inapplicable for co-optimization. The proposed approach improves the existing methods in terms of the weight function and representation parameters, making the method more suitable for the optimization and evaluation of the carbon sequestration and enhanced oil recovery process. This objective index can be used to obtain the optimization time point. To validate the proposed approach, a CO2-EOR simulation process has been evaluated using the proposed index, and the optimization time point obtained (the 6054th day, f = 1.001). The optimized process would have a better development effect on CO2-EOR by comparison of simulation results. Then, this optimal index was applied on a CO2-EOR project in Wasson oil field. The results suggest that the injection measures should be introduced at the 13th and 17th years, and this improved objective index can be effectively applied to the carbon sequestration and enhanced oil recovery process.

Application of Lucas–Kanade algorithm with weight coefficient bilateral filtration for the digital image correlation method

Application of bilateral filer weight coefficients for computing the weight function in Lucas–Kanade algorithm for optical flow determination is proposed. The obtained results based on processing different image types demonstrate the error reduction in optical flow determination. The approach to weight function parameters selection for bilateral filter is proposed and investigated.

An optimal robust controller for active trailer differential braking systems of car-trailer combinations

This paper presents an optimal robust controller for active trailer differential braking (ATDB) systems of car-trailer (CT) combinations. To design ATDB systems, controllers based on the linear quadratic regulator (LQR) technique have been explored. In these LQR controller designs, vehicle forward speed, trailer payload, etc., were assumed as constants. In reality, a CT combination is frequently confronted with variations of operating conditions and vehicle parameters, which may impose significant impacts on the lateral stability of these vehicles. This motivates the investigation into robust controller designs. An ATDB controller is designed using the µ synthesis technique. A new method using a genetic algorithm (GA) for tuning the weighting function parameters for the robust controller is presented. In the parameters tuning process, the lateral stability is emphasised and the path-following capability is considered. Simulation results confirm the validity of the ATDB controller.

Weight function of stress intensity factor for single radial crack emanating from hollow cylinder

Mode-I stress intensity factor (SIF) for single radial crack emanating from hollow cylinder in an infinite plane under complex nonlinear loadings is firstly solved with the weight function method. A weight function providing wide-spectrum expressions for such cracks is developed. The weight function based SIFs are validated against different boundary collocation based SIFs. Three correlations of weight function parameters are derived for simplifying engineering applications and numerical simulations. Finally, the parameters are applied to calculate SIF of inclined crack subjected to complex nonlinear loadings in hydraulic fracturing, and show great potential in addressing cracks initiation from hollow cylinder.

Weight function of stress intensity factor for symmetrical radial cracks emanating from hollow cylinder

Mode-I stress intensity factor (SIF) for symmetrical radial cracks emanating from hollow cylinder in an infinite plane under complex nonlinear loadings is firstly solved with the weight function method. A weight function providing wide-spectrum expressions for such fractures is developed. The weight function based SIFs are validated against different boundary collocation based SIFs. Three correlations of weight function parameters are derived for simplifying engineering applications and numerical simulations. Finally, the parameters are applied to calculate SIF of inclined crack subjected to complex nonlinear loadings in hydraulic fracturing, and show great potential in addressing cracks initiation from hollow cylinder.

Aqueous extract of Cyperus esculentus L. restores and boosts sexual competence in paroxetine-dysfunctioned male Wistar rats

Objective: To investigate Cyperus esculentus aqueous extract on paroxetine-mediated sexual dysfunction in male Wistar rats. Methods: Sexually dysfunctioned (SD) rats were orally treated with PowMaxM [reference drug (7.14 mg/kg)] and the extract (500 and 1000 mg/kg body weight) once daily for 10 days, and their sexual behavioural parameters were monitored and computed. Relative testes-body weight and testicular function parameters were also evaluated at the end of the treatment period. Results: Dim light observation on the animals revealed respective proceptive and precopulatory behaviours by the primed female animals and the extract-treated male rats. Compared with SD rats, the extract-treated groups significantly restored and improved sexual behaviour and libido as evident from the remarkably increased frequencies of mount, intromission, ejaculation as well as the significantly reduced latencies of mount, intromission, ejaculation and post-ejaculation. The significantly reduced testicular activities of alkaline phosphatase, acid phosphatase, lactate dehydrogenase and the concentrations of protein, cholesterol, glycogen, testosterone, luteinizing hormone, follicle stimulating hormone and testes-body weight in the SD rats were also markedly increased following treatment with the extract. The effects elicited by the extract competed favourably with the reference drug used. The improved sexual competences exhibited by the male rats in this study are indicative of aphrodisiac attributes of the extract and could be adduced to the presence of phytonutrients as revealed by the GC-MS chromatogram. Conclusion: The data from this study suggest that C. esculentus is capable of restoring and boosting sexual competence and the probable mechanism is via enhancement of adaptogenic bioactive principles.

Estimation of the Accuracy of Finite-Element Petrov–Galerkin Method in Integrating the One-Dimensional Stationary Convection-Diffusion-Reaction Equation

UDC 519.63; 004.75; 536.252 The accuracy and convergence of the numerical solutions of a stationary one-dimensional linear convection-diffusion-reaction equation (with Dirichlet boundary conditions) by the Petrov–Galerkin finiteelement method with piecewise-linear basis functions and piecewise-quadratic weighting functions are analyzed and the accuracy estimates of the method are obtained in certain norms depending on the choice of the collection of stabilization parameters of weight functions.