Characteristics Of Panels Research Articles

Design and Application of a Lightweight Plate-Type Acoustic Metamaterial for Vehicle Interior Low-Frequency Noise Reduction

To reduce the low-frequency noise inside automobiles, a lightweight plate-type locally resonant acoustic metamaterial (LRAM) is proposed. The design method for the low-frequency bending wave bandgap of the LRAM panel was derived. Prototype LRAM panels were fabricated and tested, and the effectiveness of the bandgap design was verified by measuring the vibration transmission characteristics of the steel panels with the installed LRAM. Based on the bandgap design method, the influence of geometric and material parameters on the bandgap of the LRAM panel was investigated. The LRAM panel was installed on the inner side of the tailgate of a traditional SUV, which effectively reduced the low-frequency noise (around 34 Hz) during acceleration and constant-speed driving, improving the subjective perception of the low-frequency noise from “very unsatisfactory” to “basically satisfactory”. Furthermore, the noise reduction performance of the LRAM panel was compared with that of traditional damping panels. It was found that, with a similar installation area and lighter weight than the traditional damping panels, the LRAM panel still achieved significantly better low-frequency noise reduction, exhibiting the advantages of lightweight, superior low-frequency performance, designable bandgap and shape, and high environmental reliability, which suggests its great potential for low-frequency noise reduction in vehicles.

Modifying 3D composite textiles as functional panels

Honeycomb fabric-reinforced composites have been widely used recently, due to their prominent properties, when compared to other materials. This is because they are lighter in weight and stronger than other materials. Thus, they can absorb different types of energies, such as mechanical and thermal energies. A multi-layer fabric is developed by creating a unique fabric structure, to enable the presence of air voids within the panels produced, which diminishes the heat transfer rate through the material. The structure applied in samples used in this manuscript is novel, as it consists of a 3D fabric produced using a traditional loom with a special technique, by dividing the warp yarns into four layers. A skin of textile, produced from textile wastes, is applied, along with the technique of hardening the 3D fabrics to keep the open areas in the structure with the aid of pre-designed pins and a resin. The composite panel was produced with the pins used to open the fabric’s structure, and the resin was applied as a matrix holding the structure and keeping its dimensions. Panels of the 3D fabric-reinforced composite obtained from cotton and polyester yarns were produced, to achieve thermal insulation and good mechanical properties, which enable the use of the fabric in various applications. The fabric has two panels of each material, one with skin and the other without skin. This skin consists of low-quality fabric, mainly made from textile wastes. The physical and mechanical characteristics of the developed panels were measured. Functional performance, such as thermal and sound properties, were also measured. Testing thermal conductivity, it was found that panels made of cotton had higher conductivity than panels made of polyester. In addition, the presence of the skin improved the thermal insulation and mechanical strength of the panels compared to those without skin. In mechanical testing, polyester-based panels showed better mechanical properties than panels based on cotton. In sound absorption testing, all samples reached the limits for sound absorption. The number of layers affected the sound absorption coefficient (SAC) and the noise reduction coefficient (NRC). Also, the presence of the skin improved NRC. Finally, all samples had an aesthetic appearance, due to the presence of surface waves, but the sample containing the polyester material, with double layers, and the laminated skin made of waste fabric had the highest functional panel performance, in terms of radar chart areas. This means that it can be used in the field of architecture as a façade panel or as an indoor wall used for isolation, which do not require paint.

Determination of I-V curves for photovoltaic generator by an analytical method; Akbaba model

In order to maximize the amount of electrical energy generated and ensure effective use, the conventional I-V or V-I characteristics derived from the diode model of Photovoltaic (PV) Solar Panels are important. Unfortunately, these features cannot be extracted using linear equations. It follows that the answer requires extremely drawn-out, time-consuming procedures. Many studies focus on calculating maximum power extraction. The analytical solutions to these equations are also nonexistent. Programming on computers can assist in solving the equations. The Akbaba Model was created specifically for the PVG to address these challenges. The Akbaba Model relies heavily on coefficients A, B, and C in this equation. The diode model serves as the true model in this case, and the coefficients A, B, and C are calculated. Another advantage of this model is that, because its qualities have partially deteriorated with time, the genuine I-V characteristics of the PV Panels can be recovered by measuring again.

Data evaluation for identifying meaningful engineering characteristics of the flexible panels used for aerial module for pedological drought

The existing worldwide information related to the aerial modules used for transporting mulching substances is particularly pernicious. Thus, at this moment, on an international level, cargo transport solutions for mulching lands affected by soil drought are limited to identifying the maximum value of the load (1250–4500 kgf), the type of raw material from which it is made (polyamide), the shape (quadratic, octagonal, rectangular) and its dimensions (2.13 m × 3 m for a maximum transport capacity of 1250 kgf – 5.5 m × 5.5 m for a maximum transport capacity of 4500 kgf). Also, among the solutions for protecting lands affected by wildfires, the sowing technique with the help of drones was identified. Thus, the seeded compost balls are allowed to fall by gravity from the drones, being released randomly in the demineralised areas, difficult to reach by land transport. The paper presents the latest research of INCDTP specialists – carried out in the national premiere – regarding the iterative-incremental development of a multi-role collapsible aerial module that has as its theatre of operations the desertified areas (due to the pedological drought) of Romania. The central point of the research is focused on: i) the experimentation in the accredited laboratories of INCDTP, of flexible panels joined by mechanical-textile technology; ii) statistical analysis of values; iii) predicting the minimum values of the physical-mechanical characteristics of the composite material.

Challenges and Opportunities of the Solar Panels Reverse Logistic in the Energetic Transitions of the Green Hydrogen

Objective: This paper aims to collaborate to the development of the reverse logistic for solar panels, impulse by the energetic transition into the green hydrogen. Additionally, it intends to map all the logistic activities linked to the green hydrogen production, including the reverse logistic of solar photovoltaic panels, to take advantage of its components. This paper wanted to identify all the photovoltaic solar panels components, for a more broadly comprehension of its structure, and define all the activities related to the post consumption of the panels. Theoretical Framework: The references explore the photovoltaic solar panels characteristics and the necessity to implement the reverse logistic for this energy source, focusing on green hydrogen production. Also, applying the just-in-time tool. Method: The methodology is detailed, with a clear and objective description of all the steps. Including the mapping of the activities through a flowchart, that illustrates the sequence of the steps, with a detailed description of each step. Results and Discussion: The obtained results revealed the necessity of a perspective for the reversed logistic driven from the energetic transition, especially by the green hydrogen. This problem is linked to the increasing environmental awareness and boosting on the solar panels production, which also increased the demand for the discarded components of those panels in a sustainable manner. Thus logistic can be optimized through the just-in-time tool, that allows the reverse mapping of the steps, improving its logistic aspects. Research Implications: The theoretical and practical implications of this research highlight mainly the questions related to sustainability and awareness in short, medium and long term. The search for an energetic vector capable of supplying the energetic necessities in a clean and abundant way is a topic of constant study. However, the answers to these questions and how they are connected can impact directly the energetic research. Therefore, it must be done in an efficient and strategic way. Originality/Value: This study explores the reverse logistics for solar panels, aiming to demonstrate the possibility to produce in a large scale in a sustainable form. This connection is linked to the GH2 energetic vector, since the source for the production of this vector is directly related to renewable energies, such as solar energy. Thus, this study maps in detail this reverse pathway searching for a sustainable reverse logistic.

Particularities on the Low-Velocity Impact Behavior of 3D-Printed Sandwich Panels with Re-Entrant and Honeycomb Core Topologies

This work describes, through experimental and numerical investigations, the mechanical behavior and energy absorption characteristics of 3D-printed sandwich panels with cellular cores subjected to low-velocity impact. Using fused deposition modeling techniques (FDM), three different sandwich panels, one with a regular hexagonal core and two with re-entrant cores at 0 and 90 degrees, were fabricated. The sandwich panels were subjected to low-velocity impact, at impact energies of 10 J and 15 J. A comprehensive investigation of the panels’ behavior through experimental testing and numerical simulation was conducted. The results indicate that the sandwich panel with a 90 degrees re-entrant core is stiffer and absorbs the largest amount of impact energy but, at the same time, suffers significant damage to the upper facesheet. The 0 degrees re-entrant core is compliant and provides both impact resistance and good energy absorption characteristics. Such a sandwich panel finds its application in the construction of personal protective equipment, where the aim is to minimize the forces transmitted during low-velocity impacts and maximize the total absorbed energy. Re-entrant core sandwich panels prove to be very good candidates for replacing the honeycomb core sandwich, depending on the desired engineering application.

Contextual factors associated with successful alcohol screening and brief intervention implementation and sustainment in adult primary care

IntroductionHazardous drinking is a public health problem affecting approximately 20 % of the U.S. primary care population. Clinical trials have documented the efficacy and effectiveness of Alcohol Screening and Brief Intervention (ASBI), yet widespread implementation remains elusive, and questions remain regarding optimal implementation and sustainment strategies. Kaiser Permanente Northern California (KPNC) implemented systematic ASBI in adult primary care in mid-2013. We used 8 years of electronic health record (EHR) data, combined with surveys which captured primary care provider perceptions organized into PRISM (Practical, Robust Implementation and Sustainability Model) implementation framework domains (Intervention, External Environment, Implementation Infrastructure, and Recipients), to characterize ASBI implementation and sustainment and test how various factors are associated with ASBI rates. MethodsUsing EHR data, we calculated yearly screening rates of adults with a primary care visit, and brief intervention (BI) rates among those with a positive hazardous drinking screen, (exceeding the age and sex-specific daily and weekly low-risk NIH guidelines (≤3 per day and ≤ 7 per week for women and older men; ≤4 per day and ≤ 14 per week for men 18–65)), across KPNC, from 2014 to 2021. We collected web-based survey data, informed by the PRISM domains, from primary care providers (n = 796; 35.5 % RR) to assess perceptions on ASBI implementation and sustainability. ResultsBetween 1/1/2014 and 12/31/21 there were 5,072,270 completed screenings and 624,167 BIs. After adjusting for patient panel characteristics, we found that facilities with higher Implementation Infrastructure domain scores, indicating more robust implementation capacity, had higher screening and BI rates; facilities with higher Intervention domain scores, indicating positive perceptions of SBIRT evidence, and facilities with higher Recipients domain scores, indicating perceived organizational robustness, clinician culture and management support; and greater perceived patient needs and their likely benefit from SBIRT, had higher BI rates. ConclusionsResults provide information on factors which may facilitate successful ASBI implementation and sustainability and could inform future ASBI implementation efforts in healthcare system settings. In particular, efforts toward bolstering an organization's implementation infrastructure capacity, prior to embarking on implementation of a systematic ASBI program, could potentially help pave the way for successful implementation.

Design, and dynamic evaluation of a novel photovoltaic pumping system emulation with DS1104 hardware setup: Towards innovative in green energy systems.

Diesel engines (DEs) commonly power pumps used in agricultural and grassland irrigation. However, relying on unpredictable and costly fuel sources for DEs pose's challenges related to availability, reliability, maintenance, and lifespan. Addressing these environmental concerns, this study introduces an emulation approach for photovoltaic (PV) water pumping (WP) systems. Emulation offers a promising alternative due to financial constraints, spatial limitations, and climate dependency in full-scale systems. The proposed setup includes three key elements: a PV system emulator employing back converter control to replicate PV panel characteristics, a boost converter with an MPPT algorithm for efficient power tracking across diverse conditions, and a motor pump (MP) emulator integrating an induction motor connected to a DC generator to simulate water pump behaviors. Precise induction motor control is achieved through a controlled inverter. This work innovatively combines PV and WP emulation while optimizing system dynamics, aiming to develop a comprehensive emulator and evaluate an enhanced control algorithm. An optimized scalar control strategy regulates the water MP, demonstrated through MATLAB/Simulink simulations that highlight superior performance and responsiveness to solar irradiation variations compared to conventional MPPT techniques. Experimental validation using the dSPACE control desk DS1104 confirms the emulator's ability to faithfully reproduce genuine solar panel characteristics.

MgO and ZnO nanofluids passive cooling effects on the electricity production of photovoltaic panels: a comparative study

AbstractOverheating of solar panels stands as a pivotal factor that impacts their conversion efficiency. Therefore, implementing cooling for solar panels is a key strategy to enhance the electrical output; due to regulating their thermal properties. This study is set out to examine, experimentally, the back-passive cooling impact of MgO and ZnO water-based nanofluids at volume concentrations of 0.01%, 0.03%, and 0.05% on the thermal and electrical characteristics of polycrystalline silicon solar panels, compared with not cooled and water-cooled panels at the same time and under the same weather conditions. The system design is cost-effective and facilitates the direct contact between the cooling fluids and the photovoltaic system. The experimental results demonstrate that the application of MgO nanofluid introduces more improvement compared to the ZnO nanofluid and conventional water cooling. The electrical efficiency enhancement attains its maximum at a volume concentration of 0.05% with 20.90% and 21.65% for MgO and ZnO nanofluids, respectively, over the non-cooled panel. Simultaneously, at this concentration, the temperature reduction achieved by MgO nanofluid is 20.72%, surpassing the 15.80% reduction achieved by the ZnO nanofluid in comparison with the reference panel.

Hydrodynamic frictional performance of fouled panels: a comparative study of different coating types.

This research study delves into the hydrodynamic frictional characteristics of fouled panels coated with different types of coatings, investigating how fouling coverage and surface roughness influence drag. The investigation incorporates data on the overall percentage coverage of fouling, as well as roughness measurements obtained through a 3D profilometer. Drag data collected from a flowcell simulation of real-world flow conditions complements these measurements. Notably, the determination of the level of fouling leverages the capabilities of CIE L*a*b as an image analysis method, focusing on the overall coverage rather than individual fouling species. The objective is to illustrate how fouled panels perform under varying flow and coating conditions compared to their clean counterparts. Furthermore, the paper proposes a roughness scaling approach that considers both the percentage coverage and measured areal roughness for each coating type, encompassing both fouled and unfouled areas. This approach provides valuable insights into the combined effects of fouling and surface roughness on hydrodynamic performance, enhancing our understanding of the intricate interplay between these factors.

Improved voltage scanning algorithm based MPPT algorithm for PV systems under partial shading conduction

Maximum Power Point Tracking (MPPT) algorithms are crucial for maximizing power extraction from photovoltaic (PV) systems. Traditional MPPT methods often exhibit suboptimal performance under partial shading conditions. Hence, advanced MPPT algorithms have been developed to enhance efficiency in such scenarios. The voltage scanning-based MPPT algorithm is notable for its superior performance under partial shading, characterized by high tracking speed and efficiency. This study introduces a novel enhancement to this method—namely, a voltage skipping algorithm designed to further improve tracking speed. Unlike conventional scanning techniques, this approach dynamically calculates skipping voltages during operation, eliminating the need for prior knowledge of PV panel characteristics. Performance evaluation was conducted using a MATLAB/Simulink model of a PV system comprising 4 series panels and a boost converter, subjected to simulations under 5 distinct partial shading scenarios. Comparative analyses with established optimization algorithms such as particle swarm optimization, cuckoo search algorithm, and grey wolf optimization highlight the proposed method's effectiveness in terms of tracking speed and maximum power output. The proposed algorithm has worked with high efficiency of 99.28 %, 99.61 %, 99.13 %, 99.16 % and 99.58 % in 5 different scenarios, respectively. By using the proposed method, a significant superiority has been achieved over other methods, with tracking speeds of 0.26s, 0.22s, 0.2s, 0.22s and 0.26s, respectively.

Low-velocity impact response and damage mechanism of cosine function cell-based lattice core sandwich panels

This study aims to investigate the impact response and damage mechanism of cosine-function cell-based (CFCB) lattice core sandwich panels. Several low-velocity impact tests were conducted to explore their advantages in impact resistance by comparing them with traditional body-centered cubic (BCC) lattice-core sandwich panels. The impact response and deformation patterns of CFCB lattice core sandwich panels with two different faceplate materials (aluminum alloy and carbon fiber reinforced plastic composite) were experimentally investigated. The CFCB lattice core sandwich panels exhibited higher impact resistance and energy absorption capacity than their BCC lattice core counterparts. Furthermore, sandwich panels with aluminum alloy faceplates provided better impact resistance capacity than those with CFRP faceplates. Subsequently, several numerical models were developed to explore the deformation mechanisms and energy absorption characteristics of CFCB lattice core sandwich panels. In addition, the effects of the core structural parameters on mechanical performance were numerically investigated. Results indicated that increasing the cell rod diameter and/or reducing the cosine period length could decrease the indentation depth and enhance crush force efficiency. Finally, based on the principle of minimum potential energy, a theoretical model was developed to predict the initial peak load of CFCB lattice core sandwich panels with isotropic faceplates. This study aimed to explore the impact response and provide design guidance for CFCB lattice core sandwich panels.

Nonlinear vibration characteristics of all-composite honeycomb-core sandwich panel: Theoretical and experimental investigation

Nonlinear vibration characteristics of all-composite honeycomb-core sandwich panel: Theoretical and experimental investigation

An Online Scanning Method to Detect the Output Characteristics of Photovoltaic Panels

An Online Scanning Method to Detect the Output Characteristics of Photovoltaic Panels

Investigation of the Mechanical Properties of Composite Honeycomb Sandwich Panels after Fatigue in Hygrothermal Environments.

Since carbon fibre composite sandwich structures have high specific strength and specific modulus, which can meet the requirements for the development of aircraft technology, more and more extensive attention has been paid to their residual mechanical properties after subjecting them to fatigue loading in hygrothermal environments. In this paper, the compression and shear characteristics of carbon fibre-reinforced epoxy composite honeycomb sandwich wall panels after fatigue in hygrothermal environments are investigated through experiments. The experimental results show that under compressive loading, the load required for the buckling of composite honeycomb sandwich wall panels after fatigue loading in hygrothermal environments decreases by 25.9% and the damage load decreases by 10.5% compared to those at room temperature. Under shear loading, the load required for buckling to occur is reduced by 26.2% and the breaking load by 12.2% compared to those at room temperature.

Study on ultrasonic lamb wave testing technology of honeycomb sandwich structures

Abstract Honeycomb sandwich composite panels have complex structures, large sizes, many types of defects, and significant sound attenuation, which lead to low efficiency and poor sensitivity of ultrasonic non-destructive testing. In the study, a non-linear ultrasonic lamb wave testing technique for honeycomb sandwich composite panels is proposed. Firstly, the anisotropic propagation characteristics and modal structure of lamb waves in honeycomb sandwich composite panels are analyzed, and the lamb wave modes with non-linear ultrasonic accumulation are excited. Secondly, the data extraction method and imaging algorithm of non-linear ultrasonic lamb wave imaging testing are proposed. Finally, an enhanced imaging algorithm is proposed to improve image quality based on the sliding window algorithm. Based on the comparative analysis of air-coupled ultrasonic testing images and metallographic tests, it can be seen that non-linear ultrasonic lamb wave testing signals can be used to characterize the damage distribution characteristics of honeycomb sandwich composite panels, display debonding and weak debonding defects, and have the advantages of being able to perform on the same side testing and high efficiency, which can be used for non-destructive testing of honeycomb sandwich composite panels.

Static and Dynamic Characteristics of 3D-Printed Orthogonal Hybrid Honeycomb Panels with Tunable Poisson’s Ratio

By adjusting the two wall angles of the orthogonal hybrid honeycomb (OHH), the tunable Poisson’s ratio change from negative to positive values and the variation in stiffness can be achieved. To effectively analyze its static and dynamic characteristics, a two-dimensional equivalent Kirchhoff–Love model (2D-EKM) is established based on the variational asymptotic method (VAM).This model aids in effectively addressing the complexity arising from anisotropy. The obtained equivalent orthotropic properties are validated through unit-cell uniaxial compression tests and three-point bending experiments on 3D-printed specimens. The numerical simulation results suggest that the VAM-based 2D-EKM can predict the in-plane and out-of-plane static behaviors of OHH panels, with a maximum error below 10%. Particularly in the dynamic analysis of a four-sided fixed OHH panel, the analysis time required by 2D-EKM is only 0.37% of that needed for the 3D FE model. The OHH-ZPR panel exhibits exceptional resistance to deformation, with a maximum deformation under in-plane tension reaching only 27% of that in the OHH-PPR panel. Moreover, each 1% increase in the height–length ratio results in a respective increase of 275.62% and 281.93% in equivalent bending stiffness along both directions. This highlights that enhancing this ratio effectively boosts the fundamental frequency compared to the elastic modulus ratio, effectively prevents low-frequency resonance occurrences, and offers vital insights for the design and optimization of OHH panels.

Forced-Vibration Characteristics of Bowtie-Shaped Honeycomb Composite Sandwich Panel with Viscoelastic Damping Layer.

The incorporation of viscoelastic layers in laminates can markedly enhance the damped dynamic characteristics. This study focuses on integrating viscoelastic layers into the composite facesheet of the bowtie-shaped honeycomb core composite sandwich panel (BHC-CSP). The homogenization of the damped BHC-CSP is performed by employing the variational asymptotic method. Based on the generalized total energy equation, the energy functional of the representative unit cell of the damped BHC-CSP is asymptotically analyzed. The warping function, derived following the principle of minimum potential energy, provides a basis for obtaining the corresponding Euler-Lagrange equation to ascertain the equivalent elastic properties of the damped BHC-CSP. Utilizing the developed two-dimensional equivalent model, the free-vibration characteristics of the damped BHC-CSP are examined across diverse boundary conditions while delving into the impact of an external viscous damping layer on the natural frequency of the damped BHC-CSP. The results reveal that intensified boundary constraints effectively diminish the effective vibration region of the damped BHC-CSP, thereby enhancing its overall stability. The introduction of a PMI foam layer proves effective in adjusting the stiffness and mass distribution of the damped BHC-CSP. Resonance characteristics are explored through frequency and time-domain analyses, highlighting the pivotal roles of the excitation position and receiver point in influencing the displacement and velocity responses. Although the stiffness is improved by incorporating a PMI foam layer, its effect on the damping performance of the damped BHC-CSP is minimal when compared to the T-SW308 foam layer.

Experimental study on overtopping failure of concrete face rockfill dam

With the frequent occurrence of natural disasters, the problem of dam failure with low probability and high risk has gradually attracted people's attention. This paper uses flume model tests to systematically analyze the overtopping failure mechanisms of concrete face rockfill dam (CFRD) and identify its failure modes. The tests reveal that the longitudinal erosion of the CFRD breach progress through stages of soil erosion, panel failures, and water flow stabilization. Meanwhile, the cross-section breach process involves the evolution of breach size in rockfill materials, including traceable erosion, lateral broadening, and breach morphology stabilization. The fracture characteristics of the water-blocking panel are primarily evident in the flow-time curve. By analyzing the breach morphology evolution processes in longitudinal and cross sections, the flow-time curve can be subdivided into stages of burst flow formation, breach expansion with flow increase, rapid increase of breach flow discharge due to panel failures, and stabilization of breach flow and size. The primary damage process of the CFRD occurs in a cyclical stage of breach expansion, flow increase, panel failure, and rapid discharge. The rigid face plate and granular body structure contribute to partial dam failure, showing a tendency for gradual expansion of the breach. The longitudinal section illustrates dam failure resulting from panel fracture and rockfill erosion interaction, while downstream slopes exhibit failure due to lateral intrusion of rockfill and cyclic instability. These research results can serve as a reference for constructing a concrete CFRD failure prediction model and conducting disaster risk assessments.

Experimental Study on the Influence of External Heat Flux and Air Pressure on the Combustion Characteristics of Solar Panels

Experimental Study on the Influence of External Heat Flux and Air Pressure on the Combustion Characteristics of Solar Panels