Harvesting System Research Articles

Optimal Control of Nonlinear, Nonautonomous, Energy Harvesting Systems Applied to Point Absorber Wave Energy Converters

Pursuing sustainable energy solutions has prompted researchers to focus on optimizing energy extraction from renewable sources. Control laws that optimize energy extraction require accurate modeling, often resulting in time-varying, nonlinear differential equations. An energy-maximizing optimal control law is derived for time-varying, nonlinear, second-order, energy harvesting systems. We demonstrate that sustaining periodic motion under this control law when subjected to periodic disturbances necessitates identifying appropriate initial conditions, inducing the system to follow a limit cycle. The general optimal solution is applied to two point absorber wave energy converter models: a linear model where the analytical derivation of initial conditions suffices and a nonlinear model demanding a numerical approach. A stable limit cycle is obtained for the latter when the initial conditions lie within an ellipse centered at the origin of the phase plane. This work advances energy-maximizing optimal control solutions for nonautonomous nonlinear systems with application to point absorbers. The results also shed light on the significance of initial conditions in achieving physically realizable periodic motion for periodic energy harvesting systems.

Distributed dynamic scheduling algorithm of target coverage for wireless sensor networks with hybrid energy harvesting system.

The integration of energy harvesting techniques has the potential to significantly prolong target monitoring in wireless sensor networks (WSNs). However, the stochastic nature of hybrid solar-wind energy arrivals poses a significant challenge to optimizing energy utilization for target coverage. To address this issue, we propose a dynamic and distributed node scheduling algorithm based on Lyapunov optimization for hybrid energy-harvesting WSNs (HEH-WSNs). By formulating the maximum long-term average coverage utility subject to peak power constraints, we utilize Lyapunov optimization theory to develop a dynamic potential game framework for target coverage optimization in HEH-WSNs. The proposed distributed dynamic target-coverage node scheduling algorithm (DTNSA) is then derived from the potential game. We present a comprehensive performance analysis of the distributed implementation and evaluate its efficiency through extensive simulations. The results demonstrate that in two distinct scenarios, specifically with different numbers of sensor nodes and target nodes, the average coverage utility of our proposed DTNSA exceeds that of existing algorithms by and , respectively. The performance of the average number of active sensor nodes decreased by and compared to existing algorithms, while the average coverage redundancy decreased by and relative to existing algorithms. Furthermore, our algorithm adapts effectively to dynamic changes in hybrid harvested energy and exhibits lower computational complexity compared to existing target coverage algorithms.

Water Quality of Rainwater Harvesting Systems and Acceptance of Their Reuse in Young Users: An Exploratory Approach

The main objective of this study is to evaluate the water quality of different rainwater harvesting (RWH) systems and the social acceptance of their reuse in young users as an exploratory approach. Three RWH systems were implemented, and the quality of harvested rainwater was evaluated focusing on physicochemical and in situ parameters. Social acceptance was studied in one of the RWH systems using an adapted technology acceptance model. An informative talk about the operation of RWH was given to the users, who were students from a rural primary school. Surveys were conducted before and after the talk to evaluate the impact of providing information to users. The social acceptance was studied in one of the RWH systems. The results indicated that the harvested rainwater from RWH systems was suitable for reuse in agriculture despite the increase in turbidity and chloride concentrations in the outlet tap. The concentration of turbidity, phosphate as phosphorus, chloride and nitrate ranged between 0.8 and 1.9 NTU, 0.01–0.2 mg/L, 2.8–5.0 mg/L and 0.3–0.9 mg/L, respectively. In the acceptance study, the survey results and correlation analyses showed that providing information to users is crucial for increasing the acceptance of RWH systems. Moreover, this study demonstrated that RWH systems are a viable alternative technology for reusing and supplying water in arid and semiarid areas.

Hydrogel-embedded vertically aligned metal-organic framework nanosheet membrane for efficient water harvesting.

Highly porous metal-organic framework (MOF) nanosheets have shown promising potential for efficient water sorption kinetics in atmospheric water harvesting (AWH) systems. However, the water uptake of single-component MOF absorbents remains limited due to their low water retention. To overcome this limitation, we present a strategy for fabricating vertically aligned MOF nanosheets on hydrogel membrane substrates (MOF-CT/PVA) to achieve ultrafast AWH with high water uptake. By employing directional growth of MOF nanosheets, we successfully create superhydrophilic MOF coating layer and pore channels for efficient water transportation to the crosslinked flexible hydrogel membrane. The designed composite water harvester exhibits ultrafast sorption kinetics, achieving 91.4% saturation within 15 min. Moreover, MOF-CT/PVA exhibits superior solar-driven water capture-release capacity even after 10 cycles of reuse. This construction approach significantly enhances the water vapor adsorption, offering a potential solution for the design of composite MOF-membrane harvesters to mitigate the freshwater crisis.

Hybridization of Cockcroft-Walton and Dickson Voltage Multipliers for Maximum Output Through Effective Frequency Dedication in Harvesting Radio Frequency Energy

Objective: This study investigates solutions to the challenges of limited RF energy harvesting by designing a hybridized voltage multiplier system aimed at optimizing output across a wide frequency range. Theoretical Framework: The research centers on the principles and comparative efficiencies of the Cockcroft-Walton and Dickson voltage multipliers, known for their applications in RF energy harvesting. These multipliers’ performance was analyzed theoretically to guide a hybrid design that could adaptively respond to input frequency variations. Method: Voltage multipliers were designed and simulated in Multisim, with further analysis in MATLAB. Both the Cockcroft-Walton and Dickson voltage multipliers were subjected to a constant input of 1V across frequencies from 50 Hz to 5 GHz to assess their respective efficiencies. Subsequently, a hybrid voltage multiplier system was developed, combining an 8-stage Cockcroft-Walton and an 8-stage Dickson multiplier. A fast Fourier transform (FFT) frequency-selective algorithm, implemented in MATLAB, dynamically directed input voltages to the optimal multiplier based on frequency. Results and Discussion: Results showed that the Dickson multiplier excelled in the lower frequency range (50 Hz to 1 MHz), achieving a maximum output of 14.763V at 5 kHz and 10 kHz. In contrast, the Cockcroft-Walton multiplier was more effective in the higher frequency range (1 MHz to 5 GHz), reaching a peak output of 6.671V at 5 GHz. The hybrid system demonstrated efficient, frequency-dependent voltage multiplication and aligned well with anticipated performance metrics, suggesting an improvement in RF energy harvesting across the tested frequency range. Research Implications: This work contributes to the field of RF energy harvesting by introducing a frequency-adaptive system that enhances voltage output through targeted frequency routing. The results underscore the potential for hybrid designs to overcome limitations associated with individual voltage multipliers, presenting a versatile approach to harvesting RF energy effectively across broad frequency spectra. Originality/Value: By implementing a hybrid approach with a frequency-selective algorithm, this study offers an innovative solution for frequency-dependent RF energy harvesting. The findings provide a foundation for future research into adaptable energy harvesting systems that optimize voltage output across diverse frequencies, with practical implications for RF-powered devices and wireless energy transfer applications.

Optimizing potassium applications and harvest strategies to boost productivity of depleting alfalfa stands

AbstractRejuvenating thinning alfalfa (Medicago sativa L.) stands with additional forage species have been ineffective in boosting productivity. Research is needed to identify practical solutions to extend the life of declining alfalfa and increase forage production. A 2‐year field study at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center in Lingle, WY, investigated the interaction effect of K and harvest time on thin alfalfa stands. Treatments were (a) six K rates (0, 56, 112, 168, 224, and 280 kg K2O ha−1 year−1) applied to a ∼10‐year‐old alfalfa in the fall of 2019 and after the final harvest in the fall of 2020, and (b) two harvest times (early harvest, late bud to early [10%] bloom; late harvest, 7–10 days after early harvest), arranged in a 6 × 2 factorial under random complete blocks with four replications. Results showed a higher yield response to K at 224 kg K2O ha−1 year−1 and early harvest, and at 168 kg K2O ha−1 year−1 and late harvest particularly in soils with high soil test K levels (>300 mg kg−1). Harvest timing influenced alfalfa's K needs, with quadratic responses of forage accumulation to K rate observed at early (p < 0.001, R2 = 0.96) and late (p < 0.001, R2 = 0.84) harvests. The 168 kg K2O ha−1 year−1 increased stem density, increasing forage accumulation and profitability under both harvest systems. Stem density significantly impacts weed competition and stand productivity, with stem counts above 590 m−2 maintaining optimal yields. Alfalfa producers worldwide, particularly in Wyoming and similar environments, can rejuvenate depleting stands by applying moderate K rates (∼168 kg K2O ha−1 year−1) and adopting early or late harvest strategies when stem densities fall below ∼430 m−2. However, when stem counts remain above this threshold and weeds are well managed, continued harvesting may be an efficient strategy.

Sustainable Agricultural Practices in Sub-Saharan Africa: A Review of Adoption Trends, Impacts, and Challenges Among Smallholder Farmers

Sustainable agricultural practices (SAPs) remain the panacea to addressing challenges relating to climate change, low rainfall, and low agricultural productivity in many rural parts of sub-Saharan Africa (SSA). These practices include but are not limited to crop rotation, intercropping, cover cropping, and conservation tillage. The aforementioned practices have been scientifically proven to enhance crop productivity while safeguarding environmental resources. This review assesses the trends, effectiveness, and challenges associated with the adoption and utilization of SAPs among smallholder farmers in the SSA region, analyzing the literature and reports from 2000 to 2024 sourced from databases such as Google Scholar and Scopus. The inclusion criteria focused on key concepts such as SAPs, adoption, and challenges. Findings indicate that crop rotation, intercropping, improved seed varieties, manure, and mulching are among the most adopted practices. In reality, practices such as conservation tillage, agroforestry, and water harvesting systems remain the least adopted practices in many rural parts of SSA. The review further reveals that challenges relating to land tenure insecurity, lack of knowledge, training, and limited access to financial institutions all have a direct or indirect influence on farmers’ choice of adoption. Overcoming the aforementioned challenges through policy interventions and capacity building is vital for improved crop productivity and rural livelihoods.

A Robust Low‐Power Power‐On‐Reset Circuit With Dual Threshold Method

ABSTRACTIn this paper, a robust low‐power power‐on‐reset (POR) circuit with dual threshold method is proposed. The current‐based circuit exhibits good robustness with respect to process, voltage, temperature, and supply ramp variations. In contrast to conventional delay‐based pulse generation approaches, a dual threshold method is introduced to generate POR and brown‐out‐reset (BOR) pulse signals, resulting in ultralow quiescent current and a compact area. Implemented in the 55‐nm CMOS process, the proposed circuit achieves an accurate trigger‐point voltage with a temperature coefficient of 90.4 ppm/°C and a deviation to the ramp time of 2.9% for a range from 100 μs to 1 s. Furthermore, the quiescent current and active area are 0.3 nA and 4834 μm2, respectively, making it particularly suitable for energy harvesting systems.

Are Climate Change Strategies Effective in Managing Urban Water Resources? The Case of Portugal

This study examines the relationship between climate mitigation, adaptation strategies, and water management practices in Portugal from 2015 to 2021. Utilizing climate and water resource data from 2015 to 2021, including meteorological data (emperature, rainfall), wastewater treatment volumes, and energy efficiency metrics, the data are sourced from national agencies such as IPMA, ERSAR, APA, and Eurostat. The methodology employs correlation analysis to assess the relationships between climate variables (e.g., temperature, rainfall) and water resource indicators (e.g., reclaimed wastewater, energy efficiency). Despite notable reductions in greenhouse gas emissions and improvements in wastewater treatment efficiency, water resource stability remains a complex issue, particularly with regional disparities such as severe droughts in the Algarve. Additionally, the study evaluates the effectiveness of rainwater harvesting systems, reclaimed wastewater, and infiltration facilities, revealing a decline in reclaimed wastewater efficiency despite increased wastewater treatment. Rainwater harvesting systems (RWHSs) offer resilience, but their broader adoption is hindered by high costs and public perception challenges. Key recommendations include the development of resilient infrastructure, enhanced support for reclaimed water use, and increased investment in research to address water management challenges amid climate variability.

Enhanced RF Energy Harvesting System Utilizing Piezoelectric Transformer

RF energy harvesting converts ambient signals into electrical power, providing a sustainable energy source. This study demonstrates the use of a piezoelectric transformer for efficient RF energy harvesting. In this work, a piezoelectric transformer (PT) is employed as a high-gain, efficient inverting amplifier to enhance RF wireless energy harvesting. The PT, composed of lead zirconate titanate (PZT), is placed after the receiving loop antenna, with its output connected to an AC-to-DC converter circuit. Maximum harvested power was observed at the PT’s resonance frequency of 50 kHz, with an optimal load of 40 kΩ. The system, comprising the antenna, transformer, and rectifier circuit, continues to resonate at 50 kHz, as confirmed by input impedance measurements, demonstrating stable and effective performance. The overall system efficiency was characterized to be 88%.

A self-powered interface circuit for piezoelectric and photovoltaic energy extracting

This paper presents a high-efficiency multi-source energy harvesting system consisting of a piezoelectric rectifier, a photovoltaic maximum power point tracking circuit and a fast self-startup circuit for powering wireless sensor nodes. Synchronous electric charge extraction techniques (SECE) are utilized to extract the piezoelectric energy when the deflection of piezoelectric energy harvester beam reaches its peak. Compared with other circuits, the proposed SECE technique can achieve piezoelectric and photovoltaic extraction simultaneously with a concise flyback topology structure. A novel maximum power point tracking method is adopted to enhance the robustness of operation against changing operating condition and improve the photovoltaic extraction efficiency. To remove the need for a battery, a simple and efficient self-startup circuit is introduced. The energy harvesting circuit is fabricated in 180 nm CMOS process. Measurement results show a fast self-startup at a relatively low light intensity of 120 lux is realized. The energy harvesting circuit is capable of outputting 189 μW power at 3.3 V piezoelectric open circuit voltage and 0.6 V photovoltaic input voltage.

Multiple solutions and orbit change in energy harvesting system with a flag configuration

AbstractThe aim of this paper is to present a methodology for implementing the high-energy orbits which is still an open problem for nonlinear energy harvesters. To achieve it, this paper presents a new design of system with a flag configuration which potential function is shaped with the use of elastic elements. We have identified the lift force in FEM for wide spectrum of air velocities and used it as excitation in dimensionless mathematical model. On this basis we have conducted simulations of energy harvesting effectiveness. In the second part of the work, we focused on identifying the coexisting solutions. Due to the existence of high-energy orbits and low-energy orbits, we conducted simulations to investigate the possibility of changing the orbit. We used the Impulse Excitation Diagram here, but supplemented it with multi-colored probability distribution maps illustrating the possibility of achieving a stable orbit at given numerical values of the impulse amplitude and duration for various values of air flow velocity. The use of probability distribution maps allow to select the optimal impulse characteristics from the point of view of the energy necessary for its initiation.

Looking back to look forward: Explorations on water scenario in Bundelkhand, Central India

At present, India is suffering from the worst water crisis in its history, and millions of lives and livelihoods are under threat. As per NITI Aayog’s1 Water Index Report (2018), 40% of the population will have no access to drinking water by 2030. A 2016 report by Down To Earth (DTE) stated that 116,000 water harvesting structures were constructed between 2006 and 2015, and 15,000 crore rupees were spent on drought-proofing measures in Bundelkhand, Central India. Still, the region had 15th consecutive crop loss and 13 droughts in the past 15 years. Water historians like Elizabeth Whitcombe, Rohan D’Souza, and others have demonstrated how British imperialism led to the replacement of traditional water harvesting structures and systems, severely altering existing water-society relationships. On the contrary, Ian Stone, David Mosse, and Esha Shah argued that the ‘pre-colonial equilibrium’ versus ‘colonial hydrology’ framework is an exaggeration. Within this context, the research reveals the tangled roots of various causes and variables, and practically informing policy circles to tackle contemporary water issues and challenges and achieve SDG 6: Clean Water and Sanitation.

Deep adversarial learning models for distribution patterns of piezoelectric plate energy harvesting

This paper presents a novel approach utilizing piezoelectric plate structures with random electrode distribution patterns for energy harvesting applications across various vibration modes. For the first time, leveraging electromechanical Finite Element Analysis (eFEA) and data extraction techniques, we investigate the integration of conditional Generative Adversarial Networks (cGAN)-based dynamic models for this purpose. The cGAN offers an effective technique for generating realistic synthetic data conditioned on input parameters, thereby enabling the creation of diverse and representative datasets for training energy harvesting systems. The integration of eFEA with cGAN opens up new possibilities for optimizing the design and performance of piezoelectric energy harvesters across various applications. Specifically, we explore four distinct cGAN models-based mechanics of energy harvesters by deploying distribution patterns. These models include training data generated by stacking simultaneously mode images, utilizing separate cGAN models for each mode, labeling images by mode, and concatenating all mode images into one. Our study focuses on assessing the effectiveness of these models in minimizing loss in cGAN-based power generation and predicting Structural Similarity Index Measure (SSIM) values, and more importantly, identifying the predicted data point outputs from the generated pixel image extractions. By analyzing the generated data from numerical model and its application in deep learning, we aim to enhance the understanding of the effects of distribution patterns and image processing techniques for optimal power generation and the effectiveness of piezoelectric energy harvesting systems across different vibration modes. The studies explore how different distribution patterns affect the power harvesting efficiency and frequency bandwidth, utilizing the generated datasets.

Paratenon-Sparing Quad Tendon Graft Harvest

Background: In recent years, the quadriceps tendon has gained popularity for primary anterior cruciate ligament (ACL) reconstruction surgery due to its robustness, easy access, and ability to be tailor-made to each patient. However, concerns remain regarding potential complications associated with quadriceps tendon harvest, including impaired healing and damage to the extensor mechanism. Indications: Preserving the quadriceps paratenon, which is a source of blood supply, nutrients, and therapeutic cells during ACL reconstruction surgery, may improve postoperative outcomes by mitigating potential adverse effects associated with quadriceps harvest. As a result, it may also facilitate the quadriceps healing process and postoperative rehabilitation. Technique Description: The incision area is marked approximately 1 cm below to 3 cm above the proximal patellar pole, and the skin is dissected from the underlying tendon, exposing both the quadriceps and its paratenon. Once the tendon insertion to the patella's proximal pole is visualized, a double-blade knife is used to make a full-thickness 2-cm longitudinal cut, taking care not to cut over 2 cm of the overlying paratenon. Then, the distal end of the tendon is safely detached from the patella followed by placing continuous whip sutures, which are then loaded on a graft harvesting system and cannula. The cannula is gently plunged underneath the paratenon while applying tension on the whip sutures with the knee flexed to 90°. Then, the cannula is twisted repeatedly under the paratenon until the desired length of 61/2 to 7 cm is reached. Again, care is taken not to lever the tendon and to harvest it along its anatomic course. Finally, the quad tendon cutter is used to transect the quad at its proximal end. During the procedure, knee extension and flexion are used to aid visualization and access to the tendon's ends. Results: Preservation of the quadriceps paratenon during its harvest for ACL reconstruction surgery can potentially improve postoperative outcomes by facilitating healing and reducing friction between the tendon and neighboring tissue. Discussion/Conclusions: Preserving the quadriceps paratenon during ACL reconstruction surgery is a technique that can be easily performed and has the potential to improve postoperative outcomes. By preserving the paratenon, surgeons can reduce potential adverse effects associated with quadriceps harvest, such as impaired healing and damage to the extensor mechanism. Based on our experience and the available literature, we believe that preserving the paratenon during quadriceps tendon harvest is a valuable technique that surgeons should consider when performing ACL reconstruction surgery. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Achieving Ultrahigh Efficiency of Triboelectric Nanogenerator Energy Harvesting Systems via Hybrid Electronic‐Spark Power Management

AbstractSignificant efforts are devoted to optimizing the efficiency of triboelectric energy harvesting systems, particularly through the design of an advanced power management system (PMS) for Triboelectric Nanoenerators (TENGs). A critical aspect of PMS is the design and control of switches. However, existing switches face significant limitations. For spark switches, precise control cannot be achieved, and electronic switches can only operate at voltages below several hundred volts which is limited by the risk of electrical breakdown. To address these limitations, a hybrid electronic‐spark switch power management system (HESS) is proposed. HESS changes the connection of capacitors from parallel to series by deploying a maximum voltage tracking switch components at the peak voltage point, resulting in a much‐elevated voltage level to activate the spark switch. This approach achieves precise control of the spark switch for the first time and significantly reduces the operating voltage of electronic switches. Through simulation and experimental verification, HESS achieves the control at a voltage level of 1.8 kV for spark switch, with an electrical component breakdown voltage of only 450 V. The power density of the HESS is 29.8 mW Hz−1 m−2, which is a new record for electronic switches.

Investigation on Wireless Energy Harvesting Techniques for Internet of Things

The Internet of Things (IoT), by collecting, processing, and uploading information from its surroundings, makes the preliminary base for the construction of a smart city. To utilize IoTs fully, establishing wireless sensor networks (WSNs) as a subset technology of the system is pivotal. Among all energy sources, the radio frequency energy, with its extensive coverage, easy accessibility, and characteristic of being free of spatial limitations, is the optimal choice for energy harvesting [1]. This project aims to conduct a thorough investigation on a wideband wireless energy harvester with high efficiency and verify its application prospect in portable power sources. I have comprehensively studied and modeled the components of a wireless energy harvesting system. I further fabricated the wireless energy harvester based on the optimized circuit diagram. It successfully featured a high sensitivity of 2701 V/W at 1.05 GHz or a wide bandwidth ranging from 0.5 GHz to 2.5 GHz. Finally, I used the devised sensor in real-life scenarios and successfully powered a thermos hygrometer and a LED. I built a network of multiple energy harvesters with an in-situ monitoring system, analogous to the IoT. In this work, I have proposed a methodology to fabricate wireless energy harvesters with high sensitivity and wide bandwidth. This research will bridge the gap between the scientific exploration for novel devices and their application in real-life scenarios.

Influence of functionalized and non-functionalized 2D graphene nanomaterial with organic phase change materials: Thermal performance comparison

Thermal energy storage and harvesting using phase change materials (PCMs) is a crucial aspect of solar thermal utilisation and energy management. However, the intrinsic limitations associated with PCMs, such as their relatively lower thermal conductivity and sluggish thermal transport pose significant obstacles in the advancement of thermal energy harvesting and storage systems reliant on PCMs. Research explored by inclusion of nanomaterial with the PCM matrix is predominant depending on uniform diffusion and stability of the developed nanocomposite. In this research endeavour, we introduce a novel and synergistic approach to synthesis a functionalized graphene nanomaterials and compare its performance with non-functionalized graphene nanomaterial at various concentrations within organic PCMs, operating at a phase change temperature of 54 °C. The formulated nanocomposite’s thermophysical properties morphology, chemical stability, optical absorbance & transmittance, melting enthalpy, thermal stability and thermal reliability were investigated using sensitive instruments. The findings unveil a remarkable enhancement in thermal conductivity with functionalized graphene dispersed PCM exhibiting an astonishing surge of 106.7 % at a mere 0.8 wt% loading, when contrasted with conventional PCM. The optical transmittance of RT54-0.8fGr was significantly reduced from 56 % to 17.2 %, which enabled the effectiveness for solar thermal energy harnessing; meanwhile the melting enthalpy was energised to 193.4 J/g from 182.6 J/g. The developed nanocomposite with better optical property and melting enthalpy were tested for 500 numbers of accelerated thermal cycles and its chemical stability and thermal property were compared with PCM. Furthermore, a heat transfer analysis is numerically simulated to exhibit the thermal conductance performance of functionalized nanocomposite PCM over base PCM. The findings suggest that the functionalized graphene dispersed PCM matrix to exhibit highly favourable attributes for renewable thermal energy storage due to their exceptional comprehensive features.

Boosting Droplet Transport for Fog Harvest.

Wedge-shaped superhydrophilic tracks have been considered as one of the most effective ways to transport droplets for diverse cutting-edge applications, e.g., energy harvesting and lab-on-a-chip devices. Although significant progress, such as serial wedge-shaped tracks with curved edges, has evolved to advance the liquid transport, the ultrafast and long-distance transporting of drop-shaped liquid remains challenging. Here, inspired by the cactus spine that enables fast droplet transport and the serial spindle knot of spider silk, which is capable of collecting condensate from a wide range of distances, we created serial wedge-shaped superhydrophilic patterns and optimized their side edges with a convex brachistochrone curve to boost the acceleration. The junctions of the serial patterns were meanwhile reformed into concave brachistochrone curves to lower the energy barrier for sustained transport. For transporting the liquid in drop shapes to the long distance at high velocity, the wedge-shaped tracks were slenderized to the greatest extent to suppress the liquid spreading and thus prevent the degradation of the Laplace driving force. Moreover, the junction that determines the energy barrier of droplet striding was carefully designed based on the principle of minimizing momentum loss. The exquisite architecture design pushed the droplet transport to a maximum instantaneous velocity of 207.7 mm·s-1 and an outermost transport distance of 120.5 mm, exceeding most wettability or geometric gradient based reports. The transported volume of the droplets can be readily regulated by simply scaling the created architectures. The enhanced droplet transport facilitates the motion and departure of the cohered droplets, enabling a 1.9-fold rise of the water collection rate and 12-fold increase of the heat transfer coefficient during the fog harvest test. This scalable, controllable, and easily fabricatable surface design provides an essential pathway in realizing high-performance manipulation of droplets and possibly pioneers substantial innovative applications in multidisciplinary fields. Those include but are not limited to energy harvesting, lab-on-a-chip devices, and MEMS systems.

Enhanced Broadband Tri-Stable Energy Harvesting System by Adapting Potential Energy – Experimental Study

Abstract This paper presents the process optimization of some key parameters, such as the size of the air gap and distance between fixed neodymium magnets to enhance the vibration-based energy harvesting effect in the tri-stable energy harvesting systems and the improved tri-stable energy harvesting system being the proposed solution under weak excitation. In order to do it, firstly the distributed parameters model of the magnetic coupling energy harvesting system, including macro fiber composites of the 8514 P2 with a homogenous material in the piezoelectric fiber layer and nonlinear magnetic force, was determined. The performed numerical analysis of the conventional and the improved tri-stable energy harvesting system indicated that introducing an additional magnet to the tri-stable system leads to the shallowing of the depth of a potential well by decreasing the air gap between magnets and consequently generating higher power output and improving the effectiveness of the proposed improved tri-stable energy harvesting system. Experiments carried out on the laboratory stand allowed us to verify the numerical results as well as determine the optimal parameters of the magnetic coupling system. Due to it, the effectiveness of the proposed system versus the conventional tri-stable energy harvesting system is most enhanced.