Load Resistance Research Articles

Microbial Load and Antibiotic Resistance Pattern of Microflora Isolated from Smoked Catfish and Mackerel Sold in Ghanaian Markets: A Potential Health Threat

Introduction: Smoked fish, particularly catfish and mackerel, plays a vital role in the Ghanaian diet, serving as a rich source of protein and essential nutrients. Smoking is a traditional preservation method widely used to extend the shelf life of fish, enhance flavor, and make it more palatable. However, despite the advantages of smoking, the process does not entirely eliminate the risk of microbial contamination, which can have significant health implications. Aim of Study: This study examined the microbial flora contamination of the smoked fish sold in Ghanaian markets. Methodology: The research was conducted in three markets: Kejetia Market, Ejura Market and Ejusu. A total of 75 different smoke-dried fish including Cat fish (Clarias gariepinus) and Mackerel (Scomber scombrus) from the markets. The fish samples were collected and kept in sterile polythene bags and transported to the laboratory for microbial analysis. Result: The study revealed that out of 75 samples analyzed, approximately 23% (n=17) were found to be contaminated with microorganisms. Escherichia coli had the highest occurrence, detected in 35.2% (6/17) of the total samples. Additionally, Shigella flexneri and Salmonella arizonae were each found in 17.6% (3/17) of the total samples. Klebsiella oxytoca was 11.7% (2/17), and Enterobacter aerogenes, Streptobacillus monilliforms, and Fusobacterium necrophorus each constituted 5.8% (1/17) of the total samples. All the identified isolates were susceptible to gentamycin (100%), and all the isolates were resistant to lincomycin (100%). Overall resistance rates for each antibiotic for all the organisms identified are lincomycin (100%), penicillin (67%), ampicillin (81%), erythromycin (65%), tetracycline (63%), neomycin (61%), cloxaxillin (43%), kanamycin (24%), and sulphamethaxole (13%). All the isolates have 100% resistance to at least three antibiotics used except for Salmonella arizonae. Conclusion: To Address these findings, a collaborative effort is required among regulatory authorities, food producers, and healthcare providers to implement stringent food safety protocols and mitigate the risks associated with contaminated fish consumption.

A Review on Analysis of Seismic Impact of Improvements with Rigid and Semi Rigid RC Structure with having Podium

Abstract: The growing population and limited land in urban areas are driving up demand for towering buildings on a daily basis. India and other emerging countries are seeing an increase in the use of tall buildings. Land becomes unavailable for further expansion in any city, particularly in major cities, beyond a certain point of horizontal development. Consequently, multi-story skyscrapers gained popularity as a means of optimising land use. The design principles used for low- and mediumrise structures are not applicable to high-rise skyscrapers. Tall structures demand the most advanced design techniques since they are intricate engineering tasks. Architects and engineers proposed/put forward the new idea of Podium sort constructions in order to meet the demands of both the growing population and the present bye-laws requiring a minimum parking space for such types of buildings. These days, tower-podium style structures are quite common since they provide for the best possible use of available space on the property and the financial leverage to meet the need for more commercial space. A portion of a structure known as a podium has lateral load resistance greater than that of a tower.

Magnetic transfer piezoelectric wind energy harvester with dual vibration mode conversion

Wind-induced vibration piezoelectric energy harvesters have garnered significant interest in recent years as a means to power autonomous wireless sensor systems. A magnetic transfer piezoelectric wind energy harvester (MT-PWEH) is proposed and its durability, power generation performance and environmental adaptability are improved utilizing dual mode conversion. This MT-PWEH incorporated a downstream rectangular baffle, which facilitated the transition of the hollow cylinder from a traditional single vortex-induced vibration to a coupled vibration involving both vortex-induced vibration and galloping (i.e., the first vibration mode conversion). Besides, the vibration direction of the hollow cylinder was perpendicular to the vibration direction of the transducer, which achieved the purpose of limiting the amplitude (i.e., the second vibration mode conversion). The feasibility of MT-PWEH was confirmed through theoretical analysis, CFD simulation, fabrication and experiments. The experimental results demonstrated that the working characteristics of MT-PWEH were significantly affected by position and size of the baffle. Specifically, the ratio of the maximum cut-in wind speed of 12.5 m/s to the minimum cut-in wind speed of 1.2 m/s reached 10.4. Additionally, a maximum power output of 0.78 mW was recorded at 10 m/s with an optimal load resistance of 800 kΩ and 10 LEDs were drove successfully.

Prediction of Mechanical Properties of Nano-Clay-Based Biopolymeric Composites.

An understanding of the mechanical behavior of polymeric materials is crucial for making advancements in the applications and efficiency of nanocomposites, and encompasses their service life, load resistance, and overall reliability. The present study focused on the prediction of the mechanical behavior of biopolymeric nanocomposites with nano-clays as the nanoadditives, using a new modeling and simulation method based on Comsol Multiphysics software 6.1. This modeling considered the complex case of flake-shaped nano-clay additives that could form aggregates along the polymeric matrix, varying the nanoadditive thickness, and consequently affecting the resulting mechanical properties of the polymeric nanocomposite. The polymeric matrix investigated was biopolyamide 11 (BIOPA11). Several BIOPA11 samples reinforced with three different contents of nano-clays (0, 3, and 10 wt%), and with three different nano-clay dispersion grades (employing three different extrusion screw configurations) were obtained by the compounding extrusion process. The mechanical behavior of these samples was studied by the experimental tensile test. The experimental results indicate an enhancement of Young's modulus as the nano-clay content was increased from 0 to 10 wt% for the same dispersion grades. In addition, the Young's modulus value increased when the dispersion rate of the nano-clays was improved, showing the highest increase of around 93% for the nanocomposite with 10 wt% nano-clay. A comparison of the modeled mechanical properties and the experimental measurements values was performed to validate the modeling results. The simulated results fit well with the experimental values of Young's modulus.

Experimental and numerical investigation in to the axial load behaviour of profiled composite walls reinforced by embedded tubes with comprehensive parametric study

This paper presents experimental and numerical investigation on the axial load behaviour of profiled composite wall (PCW) consisted of two profiled steel sheet (PSS) in-filled with concrete and reinforced with/without embedded cold formed steel tubes (CFSTs). This type of composite walls was designed to resist the in-plan axial loading (bearing wall) in buildings designed with shear walls system. The results of three different FE models, namely, NCW-FE, Oct-FE and OCT-L-FE were accurately verified with the results of three experimental specimens, namely, NCW-Exp, Oct- Exp and OCT-L- Exp. Then, after the verification study for the FE models a comprehensive parametric study was presented to show detailed information about the positive effect of the internal CFSTs thickness, number and cross sectional shapes with and without stiffeners on the axial load behaviour of the PCW. The effect of the PSSs thickness and the concrete compressive strength on the axial load resisting behaviour of the PCW was studied as well. The results of this study proved that the effects of the embedded CFSTs reduced the local buckling of the PSS and increased the ductility with the axial load resistance of the PCW.

Immunologic, virologic and drug resistance outcomes in an HIV-infected prospective cohort on treatment in South Africa.

In September 2016, South Africa introduced the Universal Test and Treat (UTT) programme to manage HIV infection. However, the development of drug resistance and sustaining viral suppression are challenges to the success of treatment programmes. This prospective observational study describes virologic, immunologic, and drug resistance profiles in a test and treat cohort in north-eastern South Africa. Five hundred and thirty-four HIV-1 positive antiretroviral naïve adults entering treatment programmes were enrolled between January 2016 and February 2018. Trends in CD4+ cell count, viral load, and drug resistance by examination of deep sequences were assessed at baseline and every three months, for 24 months. Seventy-five percent were late initiators into ART (that is baseline CD4+ cell counts < 500 cells/microliter) and 16% were early initiators into ART and baseline CD4 was not available for 9%. Eleven percent (12/104) achieved immunological response after 6 months, 39.4% (41 /104) after 12 months, and 97.5% (101/104) after 24 months. Seventy-one percent (381/534) had baseline viral loads >1000 RNA copies/ml. Nine percent (22/246) achieved viral suppression after 3 months, 50% (122/246) after 6 months and 73.6% (181/246) after 12 months. A slower viral suppression was observed for males than females (p value = 0.012). A total of 45.6% (52/114) individuals had at least one drug resistance mutation (DRM) detected at >20% threshold in any of the time points, and the number increased to 55% (63/114) when minor variants were accounted for. Forty-eight percent (14/29) had drug resistance mutations at >5% threshold as early as 3 months into treatment. The UNAIDS target of 95% viral suppression in individuals under treatment was not observed after 12 months of treatment, and this was less successful for males. Adherence and drug resistance monitoring could be beneficial for individuals harbouring resistant viruses early into treatment.

Optimizing solar energy efficiency with an improved hill-climbing maximum power point tracking control approach: hardware implementation

Abstract This article implements maximum power point tracking (MPPT) based on the improved hill-climbing algorithm for photovoltaic (PV) systems feeding resistive loads. A direct current-to-direct current boost converter is inserted between the PV system and the load to achieve matching. The converter is managed using MPPT based on the hill-climbing algorithm. The objective of this paper is to optimize the code program to achieve the best compromise between accuracy and rapidity by implementing this algorithm using a microcontroller. Two PV systems are tested under identical meteorological conditions. In the first, an improved hill-climbing MPPT controller is used whereas, in the second, the conventional version is employed. The experimental results obtained show a significant enhancement in terms of speed for the improved algorithm with a value of 0.4 s for the response time and 3% for the oscillation power; those values remain satisfactory in terms of precision of the algorithm compared with the conventional system studied and the compared algorithm from the literature.

Dynamic switching operation of diamond MOSFETs with NO2 p-type doping and Al2O3 gate insulation and passivation

Diamond metal–oxide–semiconductor field-effect transistor (MOSFET) exhibited durable and stable dynamic switching characteristics at an unprecedentedly high voltage of −105 V. Switching turn-on and turn-off times were measured to be 7.64 and 4.93 ns, respectively, with a corresponding total switching loss of 20.03 pJ for a load resistance of 50 Ω. No Miller effect was observed due to the low Miller capacitance of 11 pF/mm. This study suggests the potentiality of diamond MOSFETs in prospective high-voltage, high-speed applications.

Bio-inspired vibration isolator with triboelectric nanogenerator for self-powered monitoring

Vibration isolators are used in many engineering projects, but their real-time monitoring and early warning still a challenge. This paper presents a novel bio-inspired vibration isolator with triboelectric nanogenerator (BVI-TENG), which can be applied on vibration isolation and structural health monitoring. To find the optimal combination of parameters to achieve quasi-zero stiffness, the relationships between the force–displacement and the stiffness-displacement are investigated. After establishing the dynamic model, the effects of the different parameters on the amplitude-frequency are explored by using the harmonic balanced method. To explore the vibration isolation performance, the force transmissibility is analyzed. It was found that BVI-TENG can isolate the low-frequency and even ultra-low frequency vibration. By setting up and testing the experimental prototype, the theoretical results are verified. The energy harvesting performance of BVI-TENG is investigated by analyzing the output current, output voltage and transfer charge under different frequency. By tuning the loading resistance, the maximum output power of BVI-TENG is found. More importantly, the structural health monitoring part of the BVI-TENG produces AC signal in the safe region, which can be harvested and stored, and the signal transforms immediately into DC signal when out from this region. The performances demonstrate that the BVI-TENG can be applied to vibration isolation and serves as a self-powered structural health monitoring device to meet the needs of the civil engineering, ocean platform, and industrial robot.

An improved method for statistics estimation of out-of-plane load resistance of masonry walls using design-code models and mechanics-based finite element models

The susceptibility of masonry walls to out-of-plane failure under seismic loading presents a significant engineering concern. In adherence to contemporary limit state design philosophy and as mandated by performance-based design guidelines, it is crucial to accurately estimate statistics parameters such as the mean and variance of out-of-plane resistance. To achieve this, two deterministic models are often considered within the Monte Carlo simulation framework: design-code models, known for their computational efficiency but potential for significant model error, and mechanics-based finite element models, noted for their accuracy but computational intensity. Relying solely on either model for statistics estimation presents challenges due to their respective inherent limitations. This study introduces an improved strategy that synergizes the strengths of both models, resulting in enhanced statistics estimators for the out-of-plane resistance of masonry walls. The proposed methodology involves the use of the control variate method by integrating numerous design-code model evaluations to boost computational efficiency while incorporating a limited number of finite element model evaluations to ensure accuracy. The constructions of the proposed estimators follow rigorous optimization procedures to minimize associated errors and variances. Theoretical derivations are provided for essential elements in the estimator constructions, such as model evaluation numbers for finite element and design-code models and control variate coefficients. Moreover, the accuracy of the proposed estimators is compared with that of the crude Monte Carlo estimator. A key benefit of the proposed estimators is their unbiased nature, and their accuracy is not compromised by the discrepancies between the finite element model and the design-code model. To demonstrate the practicality of these estimators, two case studies are illustrated: one focusing on unreinforced masonry walls and the other on reinforced masonry walls. The results indicate that design-code model-based estimators exhibit large bias, and compared to the estimators that solely rely on the finite element model, the proposed estimators achieve higher accuracy given the same computational budget.

Explicit consideration of geomaterial uncertainties in the load resistance factor design of piles driven into rock-based intermediate geomaterials

The study presents a method for estimating the end bearing of piles driven into rock-based intermediate geomaterials (IGMs). Existing design methods, rooted in soil mechanics, often fall short when applied to IGMs. Moreover, the geomaterial (geological and ground properties) uncertainties are neglected and the piles are designed based on subsurface information from distant boreholes. To address this gap, the study introduces an approach that explicitly considers geomaterial uncertainties by combining empirical models and geostatistical simulation to predict end bearing. Using data from 87 piles driven into various rock-based IGMs with dynamic load testing as the construction control technique, this study introduces the Proposed Design Method (PDM) for the prediction of end bearing. PDM is compared to the Current Design Method (CDM), which is based on traditional soil-mechanics methods. Predictions from these methods are subsequently evaluated against the measured end bearings. The results demonstrate that while the PDM yields comparable predictions to the CDM, it offers a more robust consideration of geomaterial uncertainties. The PDM leads to an approximate 13.60% to 19.35% increase in uncertainties compared to CDM across various IGMs. These findings advance the understanding of pile behavior in the presence of geomaterial uncertainties and inherent variability.

Electric energy output characteristics of polyvinylidene fluoride piezoelectric transducer under pulse stress: A simplified model

Because of its excellent performance, polyvinylidene fluoride (PVDF) transducers are commonly used to convert pulse kinetic energy into electrical energy. To quantify the relationship between the transducer's input pulse stress and output electrical energy, this study established a voltage output model by simplifying the pulse stress into a triangular pulse. Then, the model's reliability was verified through three experiments, and the causes of model deviations were determined. Subsequently, the influence of the transducer (area A and piezoelectric constant K), pulse stress (pulse rise time t1 and loading rate F1), and circuit (load resistance Rm and PVDF capacitance CP) on energy conversion were analyzed with the model. Results show A, K, and F1 are directly proportional to the maximum output voltage Vmax. As Rm increases, Vmax increases and gradually approaches the limit value, AKF1t1/CP. When the peak stress remains constant, the influence of t1 on Vmax is opposite to that of Rm. When CP is larger than t1/10Rm, reducing CP leads to Vmax increases, and the increasing rate is maximized as CP approaches t1/2Rm. This study clarifies the influence of key parameters in the harvester on its energy output characteristics, which is helpful for its optimizing design in different applications.

A tunable pendulum-like piezoelectric energy harvester for multidirectional vibration

Harvesting energy from vibrations using piezoelectric mechanism has attracted much attention for powering wireless sensors over the past decade. This paper proposes a tunable pendulum-like piezoelectric energy harvester for multidirectional vibration (TP-PVEH) to enhance the power generation characteristic, durability, and environmental adaptability of energy harvester. Unlike traditional cantilevered piezoelectric vibration energy harvesters (PVEHs), which typically lowered working frequencies by adding the weight of proof mass at the end of beam or reshaping beam, TP-PVEH employed a pendulum to harness low-frequency vibrations. Moreover, in contrast to typical pendulum-like PVEHs, the pendulum in this design was not mounted at the end of beam but was attached to a radial spherical plain bearing (RSPB) structure, which avoided the irreversible beam damage caused by gravitational force. TP-PVEH utilized simple-pendulum-induced RSPB motion to smoothly pluck piezoelectric beams, subjecting the piezoelectric beams to unidirectional compressive stress only. Meanwhile, the RSPB structure's capability to facilitate multidirectional rotation enabled TP-PVEH to efficiently capture energy from various directions. Theoretical analysis, numerical analysis and experiment tests were conducted to validate the design and examine how excitation and structural parameters influenced on the output performance of TP-PVEH. The results demonstrated that the excitation amplitude, excitation angle, proof mass, and mass distance brought significant effects on the output characteristic of TP-PVEH. The working frequency, output voltage and power could be efficiently tuned by the abovementioned parameters. With an excitation amplitude of 3 mm, TP-PVEH achieved an optimal output power of 9.81 mW and an output power density of 11.37 μW/mm3, operating with a load resistance of 200 kΩ at a frequency of 12.5 Hz.TP-PVEH could power 100 blue LEDs and a calculator. Additionally, the ability of TP-PVEH to charge capacitors further demonstrated its practical power supply capabilities.

Performance comparison between PID and Fuzzy logic controllers for the hardware implementation of traditional high voltage DC-DC boost converter

This research introduces a hardware implementation of DC-DC boost converter designed to elevate the DC voltage generated by renewable sources while effectively regulating it against line and load fluctuations for inverter application. The main objective is to boost the DC link voltage to the level of Vmax in the output AC voltage obtained from inverter circuits. This enables the inverters for transformer-less power conversion from DC to AC to reduce magnetic losses, size and weight of the inverter circuits used in the utility application. The proposed converter's topology and switching sequences play a crucial role in enhancing overall performance. Utilizing a Zero Current Switching (ZCS) technique, the converter efficiently recovers stored energy from the magnetics. The proposed converter attained the output voltage of 350 V at its current of 1A from the input voltage of 20 V at its current of 19 A. The ZCS technique and the topology of the converter enhances the efficiency to 92 %. The study employs traditional Proportional-Integral (PI) and Proportional-Integral-Derivative (PID) controllers for effective voltage regulation, analysing time domain specifications. Additionally, a Fuzzy logic controller is introduced as an alternative to PID controllers to compare their performance metrics, evaluating the optimization of the converter's transient and steady-state behaviours. The proposed converter is designed, simulated and their performance metrics are analysed using MATLAB for both with and without controllers. The step-time characteristics of the proposed converter with load resistance of RL = 500 Ω and an input voltage of Vi = 20 V has been determined and analysed. The PID system attained a rise time of 88.781 ms, an overshoot value of 9.341 %, and a steady-state error of 0.00043. The fuzzy system achieved a low-rise time of 10.624 ms, a low overshoot of 0.55 %, and a steady-state error of 0.0584. The hardware prototype of the proposed converter is implemented with a FPGA based PID and Fuzzy logic controllers for providing better voltage regulation and to improve the performance metrics of the converter. The simulation and experimental findings are contrasted, examined, and confirmed to ensure improved consistency in performance measures.

Facile synthesis and electrochemical performance of bacterial cellulose/reduced graphene oxide/NiCo-layered double hydroxide composite film for self-standing supercapacitor electrode

This study employs a cost-efficient method to create a pliable BC/rGO-NiCo-LDH electrode film on a bacterial cellulose base. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analyses verified the incorporation of reduced graphene oxide (rGO) and nickel–cobalt layered double hydroxide (NiCo-LDH) into the bacterial cellulose structure. The BC/rGO-NiCo-LDH composite material exhibited high-temperature stability and achieved a specific capacitance of 311 F g−1 at a scan rate of 0.1 mV/s, surpassing that of earlier cellulose electrodes. The electrode film showed exceptional mechanical capabilities, displaying flexibility and load resistance without any structural damage. The film’s flexibility and lightweight properties were improved due to the low density of 0.656 g cm−3, which is a result of the nanoporous structure and intrinsic low density of rGO and cellulose. A retention ratio of 0.40 for storage modulus at a glass transition temperature of around 90°C demonstrated positive mechanical performance. This cost-effective and uncomplicated synthesis approach produced a BC/rGO-NiCo-LDH electrode with potential. The material possessed favourable mechanical and electrochemical characteristics, making it suitable for wearable electronics.

Ultimate internal pressure bearing capacity of unconstrained and constrained X80 oil and gas pipelines with three typical dents

Three typical dents, denoted as types I, II, and III, encapsulate the prevailing manifestations of mechanical impairment encountered by oil and gas pipelines. Presently, scholarly attention is predominantly directed towards the scrutiny of load-bearing capabilities in pipelines afflicted by a solitary type of dent. To unravel the intricate impact of three typical dents on the performances of dented pipelines, three distinct models of pipeline dents under different constraints were studied in this work. These findings reveal that unconstrained dents consistently exhibit greater plastic strain and deformation zone dimensions compared to their constrained counterparts. The spring-back and rebound performances in unconstrained pipelines were fortified and the external load resistance in constrained pipelines was enhanced by augmenting the indenter diameter and introducing internal pressure. Both unconstrained dents and type I constrained dents failed consistently in the non-dented region, with their ultimate internal pressure resistance unaffected by the constraining factors. In contrast, type II and III constrained dents, featuring smaller indenters, greater dent depths, and reduced diameter-to-thickness ratios, failed within the dented region, which results in a weakened ultimate internal pressure-bearing capacity. Failure occurred in the non-dented region under opposite conditions, leaving the internal pressure resistance unaffected. Finally, dimensionless predictive formulas for the ultimate internal pressures of the type II constrained and type III X80 dented pipelines were obtained through nonlinear fitting. This comprehensive exploration revealed the variations in the ultimate internal pressure-bearing capacities induced by dents, thereby providing valuable insights for pipeline design and safety considerations.

Ground motion parameters and damage correlation in plan irregular L-shape steel structure with BRB

Irregularly designed structures frequently experience greater damage compared to regular buildings as a result of elevated torsional reactions and stress concentration, as indicated by evaluations of damage carried out subsequent to past seismic events. The irregularities in the plan configuration provide significant issues for building seismic design. One example of an irregularity is the re-entrant corners found in L-shaped structures, which can lead to early collapse by causing stress concentration from abrupt changes in stiffness and torsional response amplification. More than ever, a thorough investigation into the relationship between the issue of ground motion parameters (GMPs) and Damage is required because of the complex way that L-shaped buildings respond to earthquakes. The current study examines the relationship between a large number of commonly used GMPs and the associated damage for three-, six-, nine-, and twelve-story 3D buildings—that is, low-, mid, and high-rise structures—with asymmetric L-shaped plan layouts. The system of lateral load resistance that was used was Buckling Restrained Brace Frames (BRBFs). To assess a building's seismic performance, 15 bidirectional earthquake ground motions were applied using Nonlinear Time History Analysis (NTHA) for incident angles of 0°, 45°, 135°, 225°, and 315°. The structural response is reported in terms of the average and maximum inter-story drift as well as the total Park-Ang damage index. The relationship between GMPs and structural damage was then investigated using Pearson's correlation coefficient. The results indicate that the highest link with damage measurements is found for 3- and 6-story structures when looking at the spectral acceleration at the fundamental period, Sa(T1). However, PGD and SMV exhibit a stronger correlation than other GMPs for structures with nine and twelve stories. Additionally, Classification and Regression Trees (CART) is a decision tree algorithm used for predictive modeling. In this study suggested using CART (Classification and Regression Trees) algorithms to estimate the link between GMPs and Damage Indices. The findings demonstrate the ability of CART algorithms to extract the rules and correlations governing earthquake damage.

Finite Element Analysis and Optimization of the Piezoelectric Circular Diaphragm Energy Harvester

The effectiveness of power generation of the piezoelectric energy harvester (PEH) depends on the coupling between its resonant frequency and the oscillation frequency of the vibration source. The resonant frequency of a PEH is determined by its structural design, and therefore, to improve piezoelectric energy harvester performance, the piezoelectric energy harvester must be optimally designed to achieve the resonant frequency that matches the excitation frequency of the vibration source. This paper presents the design and detailed calculation of the piezoelectric energy harvester in the form of a bimorph piezoelectric circular diaphragm (PCD) structure by finite element analysis (FEA) using the software package ANSYS. Based on analyses and calculations, the optimal structure of the piezoelectric circular diaphragm energy harvester is proposed to meet the specified resonant frequency response matching the vibration source frequency. Detailed calculations of the PEH were performed with an excitation frequency of 100 Hz. With an optimal load resistor of 10.1 kΩ, an output power of 0.287 W was generated at 100 Hz (equal to the resonant frequency of the PEH) under an amplitude of harmonic excitation of 0.1mm. In addition, the research results can be used to fabricate piezoelectric circular diaphragm energy harvester operating at a resonant frequency suitable for the available vibrations.

Design and development of a compact, wide-angle metamaterial electromagnetic energy harvester with multiband functionality and polarization-insensitive features

This article presents a compact, wide-angle, polarization-insensitive metamaterial harvester that can efficiently harvest electromagnetic (EM) energy in the S, C, X, and Ku bands. The harvester's unit cell consists of a split ring resonator, two strip lines, and two split strip lines, giving it a total size of (10 × 10) mm2. Each split gap is filled with a 50 Ω resistive load. The input impedance of the harvester is precisely designed to match that of free space, allowing for efficient absorption of EM power and appropriate redirection towards the resistive loads. The harvester's performance is also evaluated for various polarization and incident angles, considering the Transverse Electric and Transverse Magnetic modes. The simulation results reveal that the proposed harvester exhibits a notably greater conversion efficiency of around > 95%. The simulation outcomes were carefully validated through experimental tests conducted in an anechoic chamber using a 3 × 3 cell array of the proposed design. This ensured the accuracy and reliability of the results. The strong correlation between the experimental data and the full-wave simulations strongly supports the effectiveness of the proposed harvester. Therefore, the demonstrated efficiency and compact size make it a perfect fit for energy harvesting systems in wireless sensor networks.

Analysis, design, and optimization based on genetic algorithms of a highly efficient dual-band rectenna system for radiofrequency energy-harvesting applications

This paper gives an enhanced Rectenna design that operates at dual-band [2.45 and 5.8] GHz in the ISM (Industrial, Scientific, and Medical) band and is printed on an FR4-Epoxy substrate. This Rectenna design includes two proposed sub-designs for the receiving antenna and rectifier circuit based on the microstrip technology. The first sub-design concerns the microstrip patch antenna (MPA) described by its radiating element as a pentagonal, its ground being affected by a defective ground structure technique, and its polarization manner as circular polarization. This MPA design is analyzed, designed, optimized using genetic algorithms (GAs), simulated under CST MWS (i.e., computer simulation technology microwave studio), and confirmed by another software named HFSS (high-frequency structure simulator). The second sub-design concerns the microstrip rectifier circuit (MRC) that contains an input matching network based on a coupled-line impedance transformer strategy to achieve good adaptation between MPA and MRC, voltage doubler converter using an SMS7630 Schottky diode thanks to its high sensitivity, microstrip interdigital capacitor to mitigate the intrinsic losses due to the lumped elements, harmonic rejection filter based on a stepped-impedance low-pass filter to reject the unwanted harmonics generated by the non-linear behavior of SMS7630, and the resistive load that models the consumption of the system to be fed. This MRC is analyzed, designed, optimized using GAs, and simulated under ADS (Advanced Design System). The effectiveness of the proposed MPA is proven in terms of gain equals 3.06 dBi and 4.683 dBi at 2.45 GHz and 5.8 GHz respectively, and efficiency equals 95.13 % and 96.552 % at 2.45 GHz and 5.8 GHz respectively. The proposed MRC is effective in terms of efficiency at a lower input power value of about 97.18 % and 67.93 % at 2.45 GHz and 5.8 GHz respectively.