Single Harvest Research Articles

Design and Optimization of Piezoelectric Cantilever Beam Vibration Energy Harvester.

Piezoelectric cantilever beams are commonly utilized to harvest energy from environmental vibrations due to their simple structures. This paper optimizes a single crystal trapezoidal hollow structure piezoelectric cantilever beam vibration energy harvester with a copper substrate to achieve high energy density at a low frequency. Finite element analysis (FEA) is adopted to optimize the size of the copper substrate at first, and the piezoelectric energy harvester (PEH) is further optimized with a trapezoidal hollow structure under the optimal size of the copper substrate. The developed PEH with a trapezoidal hollow structure (La = 20 mm, Lb = 15 mm, and Lh = 40 mm), with a copper substrate of 80 mm × 33 mm × 0.2 mm, can obtain the best output performance. Under the condition of 1 g acceleration, the resonance frequency and peak voltage output were 23.29 Hz and 40.4 V, respectively. Compared with the unhollowed PEH, the developed trapezoidal hollow structure PEH can reduce its resonant frequency by 12.18% and increase output voltage by 34.67%, while also supplying a power density of 7.24 mW/cm3. This study verified the feasibility of the optimized design through simulation and experimental comparison.

Biomass partitioning of plants under soil pollution stress

Polluted sites are ubiquitous worldwide but how plant partition their biomass between different organs in this context is unclear. Here, we identified three possible drivers of biomass partitioning in our controlled study along pollution gradients: plant size reduction (pollution effect) combined with allometric scaling between organs; early deficit in root surfaces (pollution effect) inducing a decreased water uptake; increased biomass allocation to roots to compensate for lower soil resource acquisition consistent with the optimal partitioning theory (plant response). A complementary meta-analysis showed variation in biomass partitioning across published studies, with grass and woody species having distinct modifications of their root: shoot ratio. However, the modelling of biomass partitioning drivers showed that single harvest experiments performed in previous studies prevent identifying the main drivers at stake. The proposed distinction between pollution effects and plant response will help to improve our knowledge of plant allocation strategies in the context of pollution.

A non-time division multiplexing single inductor solar and piezoelectric energy multi-input harvesting interface circuit

Due to time-varying and instability, single environmental energy cannot provide reliable energy for wireless sensor network nodes. Therefore, researchers propose to use multi-source synergy to provide power. Still, these circuits take time-division multiplexing or setting priority, which can only harvest one kind of environment energy at a particular moment, resulting in low energy harvesting efficiency and complex circuit structure. Also, a single vibration source is configured with multiple piezoelectric (PZT) harvesters to obtain more power. For the above questions, this paper proposes a non-time-division multiplexing single-inductor synchronous electric charge extraction circuit (NTD-SECE), which is mainly composed of rectifier bridge, peak detection circuit, control circuit, input comparison circuit, and buck-boost circuit. Theoretical analysis and experiments verify the effectiveness of the interface circuit. The results show that NTD-SECE can extract energy from photovoltaic (PV) and multi-PZTs by non-time division multiplexing, the maximum power is 450 mW. It has broad application prospects in the energy supply of low-power equipment.

Parametric analysis of hybrid tribo-piezoelectric energy harvester

Energy harvesters are widely used in various fields for environmental energy harvesting purposes. Due to the less power output of a single energy harvester, researchers are working on hybridizing energy harvesters. This paper presents a hybrid model of d33 mode piezoelectric energy harvester (PEH) and vertical contact mode triboelectric energy harvester (TEH). A Polyvinylidene fluoride (PVDF) composite film is used for the PEH unit, and a Polydimethylsiloxane (PDMS) composite film is used for the TEH unit. The effect of various design parameters like material, structural and experimental parameters are numerically investigated for a periodic motion of hybrid tribo- piezoelectric energy harvester (HTPEH). A genetic algorithm has been used to maximize the harvested energy. This study will help design the prototype of HTPEH according to applications. The HTPEH can generate a significant amount of energy which can be helpful in the applications like designing self-powering electronic devices, robotics, sensors, and harvesting the vibration energy from human, wind, or ocean motion.

Sunlight‐Coordinated High‐Performance Moisture Power in Natural Conditions

AbstractIt is a challenge to spontaneously harvest multiple clean sources from the environment for upgraded energy‐converting systems. The ubiquitous moisture and sunlight in nature are attractive for sustainable power generation especially. A high‐performance light‐coordinated “moist‐electric generator” (LMEG) based on the rational combination of a polyelectrolyte and a phytochrome is herein developed. By spontaneous adsorption of gaseous water molecules and simultaneous exposure to sunlight, a piece of 1 cm2 composite film offers an open‐circuit voltage of 0.92 V and a considerable short‐circuit current density of up to 1.55 mA cm−2. This record‐high current density is about two orders of magnitude improvement over that of most conventional moisture‐enabled systems, which is caused by moisture‐induced charge separation accompanied with photoexcited carrier migration, as confirmed by a dynamic Monte Carlo device simulation. Flexible devices with customizable size are available for large‐scale integration to effectively work under a wide range of relative humidity (about 20–100%), temperature (10–80 °C), and light intensity (30–200 mW cm−2). The wearable and portable LMEGs provide ample power supply in natural conditions for indoor and outdoor electricity‐consuming systems. This work opens a novel avenue to develop sustainable power generation through collecting multiple types of natural energy by a single hybrid harvester.

Improving the Electromagnetic Vibration Energy Harvester Performance by Using a Double Coil Structure

The power generation capability of an electromagnetic vibration energy harvester augmented with an additional coil was investigated and compared with that of a standard single coil electromagnetic energy harvester. A single degree of freedom model and the corresponding equivalent electric circuit were employed for the analysis of the standard and of the augmented harvesters. The harvester model was validated by means of an accurate experimental characterization of a commercial electromagnetic harvester, i.e., the model-D by ReVibe. The electric circuits for the standard and for the augmented harvesters were implemented by electronic components and experimentally tested to determine the maximum power they are able to generate in four test conditions. Results from simulations and from experiments showed significant improvement of the power extraction performance exhibited by the double coil energy harvester, particularly at frequencies lower than the harvester mechanical resonance frequency.

Calibration and validation of the FAO AquaCrop water productivity model for cassava (Manihot esculenta Crantz)

FAO’s water-driven crop growth simulation model, AquaCrop, was calibrated and validated for cassava (Manihot esculenta Crantz). Existing datasets, used in similar published works, were shared covering several years and regions (Colombia, Nigeria and Togo). Different varieties were tested for the case of Colombia and a single variety (TME-419) for Nigeria and Togo. Overall calibrated biomass simulations resulted in an R2 of 0.96 and a RMSE of 1.99 tonne DM/ha. As for dry tuber yield estimates, it was not possible to find a single harvest index for the ensembled varieties given their varying characteristics and limited data per variety. However, for the TME-419 variety (Nigeria and Togo) calibrated root tuber simulations yielded and R2 of 0.94 and a RMSE of 2.37 tonne DM/ha. A single crop-file was developed for different cassava varieties and agro-ecological regions, which can be applied with confidence to further study cassava related food security, water productivity, improved agronomic practices, etc.

The Power of Markets: Impact of Desert Locust Invasions on Child Health

This paper investigates the consequences of a locust plague that occurred in Mali in 2004. We argue that in agricultural economies with a single harvest per year, this type of shock can affect households through two channels: first, a speculative/anticipatory effect that kicks in during the growing season, followed by a local crop failure effect after harvest. We show that, in terms of health setbacks, children exposed in utero only to the former suffered as much as those exposed to the latter. We also document a substantial impact of the plague on crop price inflation before the harvest, as well as a stronger crop failure effect for children born in isolated areas.

The Viability of Palatal Connective Tissue Graft Using Single Incision Versus De-Epithelialization Harvesting Technique in New Zealand Rabbits.

The Viability of Palatal Connective Tissue Graft Using Single Incision Versus De-Epithelialization Harvesting Technique in New Zealand Rabbits.

Enhanced Atmospheric Water Harvesting with Sunlight-Activated Sorption Ratcheting.

The global challenge of clean water scarcity needs to be confronted with novel sustainable, climate neutral solutions, over the entire spectrum of possible clean water availability. Atmospheric moisture represents a major untapped resource that can be harvested by sorbents, enabling water production in dry inland regions where it is needed. While benefiting from the utilization of an important renewable energy source, solar-driven, sorbent-based atmospheric water harvesting systems are inseparably based on a single water harvesting cycle per day, which severely limits the daily water productivity and the competitiveness of this very promising technology. Here, we rationally design an atmospheric water harvesting strategy, using durable hydrogel sorbents, that operates with sorption "ratcheting"─a large sequence of rapid adsorption and subsequent desorption steps─activated by direct sunlight. Employing theoretical considerations, we tailor the ratcheting timescales to the inherent sorption properties of the hydrogels, optimally exploiting their natural harvesting capabilities, while maintaining the sustainable utility of the daily cycle. Amplified by the favorable sorption properties and ratcheting stability of the sorbent, this strategy demonstrates an impressive ∼80% increase in water harvesting yield over the daily cycle systems. The generic nature of the ratcheting concept shows great potential to advance the water harvesting capabilities of a range of related systems.

Within-plant variability in blueberry (Vaccinium corymbosum L.) II: Is a shorter harvest interval always the ideal strategy to maximize fruit firmness?

Harvesting blueberries at an optimal maturity stage, is an important determinant of quality, especially when fruit are intended for long term storage. However, because blueberries set and ripen asynchronously, several pickings are needed. In general, shorter harvest intervals (<4 d) are advised to maximize fruit firmness, but due to labor shortages, the industry has sometimes been forced to increase the number of days between harvests. Thus, the objective of this study was to compare the postharvest impact of picking regimes where labor is not limiting (every 3 d) vs. a strategy driven by a labor shortage that would force a single harvest on the ninth day (9 d) in two cultivars with contrasting ripening windows: ‘Duke’ (∼30 d) and ‘Brigitta’ (∼60 d). Following an initial synchronizing picking (∼4 – 7% full blue fruit), harvest interval intensity was studied: harvests after 3 d (3 × 1), after 3 and 6 d (3 × 2), after 3, 6, and 9 d (3 × 3), and after 9 d (9 × 1). Of these, only 3 × 1, 3 × 3, and 9 × 1 were evaluated. Fruit position within the canopy (east- and west-oriented sides) was considered as a second factor. Data suggests that shorter harvest intervals (3 d) would be more suitable for cultivars with a prolonged ripening window (e.g., ‘Brigitta’) compared to a cultivar with shorter harvest season (e.g., ‘Duke’), for which longer cycles (9 d) would be preferred. Although the results show that, at harvest time, the picking management strategy had a greater effect than east-west position of the fruit, interactions between the factors were found after storage. Finally, although firmness values at harvest can be an important descriptor of storage potential of each cultivar, the rate and extent of softening after harvest were also strongly impacted by the cultivar.

A Dual Resonance Electromagnetic Vibration Energy Harvester for Wide Harvested Frequency Range with Enhanced Output Power

A dual resonance vibration electromagnetic energy harvester (EMEH) is proposed in this paper to extend frequency range. Compared with the conventional dual resonance harvester, the proposed system realizes an enhanced “band-pass” harvesting characteristic by increasing the relative displacement between magnet and coil among two resonance frequencies with a significant improvement in the average harvested power. Furthermore, two resonant frequencies are decoupled in the proposed system, which leads to a more straightforward design. The proposed dual resonance EMEH is constructed with a tubular dual spring-mass structure. It is designed with a serpentine planar spring and the coil position is optimized for higher power density with an overall size of 53.9 cm3 for the dual resonance EMEH. It realizes an output power of 11 mW at the first resonant frequency of 58 Hz, 14.9 mW at the second resonant frequency of 74.5 Hz, and 0.52 mW at 65 Hz, which is in the middle of the two resonance frequencies. The frequency range of output power above 0.5 mW is from 55.8 Hz to 79.1 Hz. The maximum normalized power density (NPD) reaches up to 2.77 mW/(cm3·g2). Compared with a single resonance harvester design under the same topology and outer dimension at a resonant frequency of 74.5 Hz, the frequency range in the proposed EMEH achieves more than a 2× times extension. The proposed dual resonance EMEH also has more than 2 times wider frequency range than other state-of-art wideband EMEHs. Therefore, the proposed dual resonance EMEH is demonstrated in this paper for a high maximum NPD and higher NPD over a wide frequency range.

Increasing productivity of mungbean (vigna radiata (l.) Wilczek) under subsistence farming in Eastern Indonesia

Mungbean is one of the major food legume and cash crops grown and consumed by small holder farmers under rain-fed conditions in Eastern Indonesia. However, the mungbean productivity has been low, less than 1 ton ha−1 due to a number of reasons including poor awareness about new varieties and skills of crop management. Two trials: varietal trial and management practices were conducted at Malaka District, East Nusa Tenggara during wet season 2008. The varietal trial in six sites resulted in identification of Sriti, Murai, Betet, and Vima 1 varieties had high productivity (1.1-1.5 t ha−1) with single harvest, shorter maturity, compared to the local varieties which were characterized by lower productivity (1.0-1.1 t ha−1), multiple harvests and longer maturity. The management practices found that selected varieties in combination with improved technology gave doubled seed yields compared to the yields when grown using local technology. These activities showed a reliable pathway to increase productivity of mungbean at small holder levels. The varietal and agronomic management trials demonstrated the impact of the technologies on mungbean productivity at small holder levels and identified future needs to sustain food productivity in remote regions on Eastern Indonesia.

Sugar maple (Acer saccharum) Seedling Bank Response to Storm Disturbance and Single Tree Selection Harvest in the Southern Keweenaw Peninsula, Michigan

This case study seeks to fill a critical knowledge gap regarding how natural wind disturbance affects stand and seedling bank diversity in mixed northern hardwood forests managed by single tree selection harvest methods. Contemporary timber harvests on state managed lands in Michigan's Upper Peninsula employ single tree selection cutting methods to promote more complex age structure in second growth stands dominated by sugar maple (Acer saccharum). However, concern exists that single tree selection harvest may result in lowered compositional diversity of seedlings as the low light conditions of small dispersed gaps exclude less shade tolerant species from gap regeneration. In July 2016 severe thunderstorms with winds in excess of 145 km/h (90 mph) caused extensive tree fall and canopy gap creation in second growth mixed northern hardwood forests in the southern Keweenaw Peninsula. We measured the species composition of overstory tree mortality and understory seedling regeneration in 14 storm gaps created in stands with and without previous single tree selection harvest. Storm gaps ranged in size from 125 to 1100 m2. American basswood (Tilia americana) was disproportionately wind-thrown. Robust seedling regeneration was released in all storm gaps, with sugar maple comprising more than 75% of mean seedling abundance, regardless of previous single tree selection harvest. Sugar maple and ironwood (Ostrya virginiana) comprised 80% of sapling abundance. Results indicate single tree selection of mixed northern hardwood stands does not exacerbate, but rather emulates, dense sugar maple regeneration found on unmanaged second growth sites.

Lifetime estimation of single crystal macro-fiber composite-based piezoelectric energy harvesters using accelerated life testing

Piezoelectric energy harvesters (PEHs) based on single crystal macro fiber composites (SFCs) have been widely utilized in vibration sensing, energy conversion, and power portable/wearable electronic devices. Despite growing attention to improve the output power of PEHs, few dedicated studies on reliability, especially on estimation of the usable lifetime of PEHs, have been reported. In this paper, an accelerated life test is applied to d32-type hard SFC-based PEHs to efficiently estimate usable lifetime in a short period of time. High temperature is used as environmental stress to accelerate the life of the PEHs, and time-to-failures are collected according to the criterion of a 10% drop in output power at 45, 55, and 70 °C under a mechanical vibration of 4.9 m/s2. The statistical failures distribution is analyzed using the Arrhenius-Weibull model with an activation energy (Ea) of 2.36 eV and a shape parameter (β) of 1.44. Accordingly, the average lifetime to failure of the PEHs in normal use (i.e., at room temperature) is determined as 4.3 × 109 vibration cycles. In addition, each failure mode is assessed to identify vulnerable points that reduce the lifespan of SFC-based PEHs. This study provides insight for evaluating and enhancing the reliability of PEHs as a basis for future practical application.

Substantiation of the size of the working slits of the cotton picking machine operating on the “One-and-a-half processing” technology for harvesting

The article describes the control system of the four-row MX-2.4 vertical spindle cotton picking machine, which uses a new technology of “one-and-a-half processing” of cotton rows-a single harvest in two consecutive passes on the machine. One of the main technological parameters of the typewriter - the method of selecting the width of the working slit-is given in the implementation of the first and second harvests “in one field-at the same time-in one machine”.

Evaluation of the Enzymatic Saccharification Efficiency of an Energy Crop, Erianthus arundinaceus, Pretreated with Ca(OH)2 Using both Countercurrent Washing System and pH Adjustment by Nonpressurized CO2.

Erianthus arundinaceus (ER) is greatly appreciated among domestic energy crops in Japan for the production of fermentable sugars from lignocellulosic polysaccharides. In this study, we developed an efficient Ca(OH)2-based pretreatment of both stems and leaves of ER at ambient temperature with the addition of a washing step for enzymatic saccharification. The recoveries of glucans and xylans in the pretreated ER after four countercurrent washing cycles were 91 and 76 %, respectively, the former being considerably higher than that of rice straw (RS) (72 %). Their saccharification ratios in the washed sample under the pressure of 1 atm CO2 were 80 and 92.5 %, respectively. The application of this simple sugar production process from ER would further support the domestic bioprocess development. ER is also foreseen to provide the additional feedstock favorable for harvesting from winter to spring in Japan, preventing a risk for feedstock shortage generated by single harvesting such as RS.

Electromechanical Performance Analysis of the Hybrid Piezoelectric-Electromagnetic Energy Harvester under Rotary Magnetic Plucking Excitation

This paper presents an analysis of the hybrid piezoelectric-electromagnetic energy harvester (P-EMEH) driven by contactless rotary magnetic plucking. A lumped-parameter model of the hybrid P-EMEH is developed, and the model parameters are determined from the finite element analysis (FEA) method. A parametric study is conducted to investigate the effects of driving force parameters, load resistance, and electromechanical coupling strengths (EMCSs) on the maximal displacements and velocities, average power inputs and outputs, and energy efficiencies of the system for indicating the performance of the hybrid P-EMEH. The results show that the hybrid P-EMEH can obtain the improved power inputs by reducing the gyration radii of the rotary magnet and shortening the gaps between the two magnets. The structural vibrations can be strongly suppressed owing to the optimal piezoelectric power outputs, which can lead to the occurrence of valleys’ power of the electromagnetic element. At weak coupling, the hybrid P-EMEH can achieve higher power outputs than the single piezoelectric energy harvester (PEH) and the single electromagnetic energy harvester (EMEH). At strong coupling, the use of the PEH is more advantageous for energy harvesting due to wider power bandwidths at high dimensionless frequencies when compared with the hybrid P-EMEH. This work provides a fundamental understanding on the effect of load resistance and EMCSs on the dynamic and electrical characteristics of the magnetically plucked hybrid P-EMEH.

Accelerated Shelf-life Testing to Predict Quality Loss in Romaine-type Lettuce

The postharvest life of lettuce (Lactuca sativa) is variable and negatively affected by mechanical injury, incomplete cooling, and poor genetic quality. Lettuce breeders are developing cultivars with a longer shelf life and rely on subjective, destructive, and time-consuming methods for quality analysis. One method of accelerating quality evaluations is known as accelerated shelf-life testing (ASLT), which has the potential to assist breeders in assessing lettuce quality and shelf life. The objective of this research was to determine the quality traits that significantly affect shelf life to develop an ASLT procedure to rapidly assess the postharvest quality of lettuce accessions in breeding programs. In Test 1, Romaine lettuce quality was evaluated using one subjective and five objective parameters during storage at 5, 10, 15, or 20 °C. Results determined that weight loss, lightness*, and hue* angle were best correlated with the overall appearance rating, whereas storage at 10 or 15 °C differentiated the shelf-life potential quickly and without excessive deterioration. In Test 2, these objective characteristics and storage temperatures were used to study rates of quality deterioration of a commercial Romaine cultivar (Okeechobee) and a breeding line (60182), both with long shelf lives, and a Batavia lettuce cultivar (La Brillante) with a short shelf life. Lettuce was evaluated during storage at 10 °C (winter and spring seasons) or at 15 °C (winter season). Weight loss was the most appropriate quality index for lettuce at these storage temperatures for a single harvest, whereas lightness* and hue* angle were the most appropriate indices for comparing quality between harvests. To apply ASLT to postharvest assessments of lettuce, breeders and other researchers should include two controls with good and poor shelf life (similar to ‘Okeechobee’ and ‘La Brillante’, respectively) as standard baseline cultivars during storage at either 10 or 15 °C.

A study of a new hybrid vibration energy harvester based on broadband-multimode

To improve the energy conversion efficiency and working frequency bandwidth of a single frequency piezoelectric vibration energy harvester, a new type of hybrid vibration energy harvester is developed which is combined with the mechanism of piezoelectric and electromagnetic energy conversion. The system comprises of a PZT cantilever beam, an elastic suspended magnetic mass, a magnet block attached to the end of the cantilever beam and a resonator. The addition of resonator can not only increase the mode, but also adjust the frequency of harvester flexibly. Nonlinear magnetic force of magnet block not only broadens the frequency band and improves the output performance of the system, but also changes the resonant frequency to make the harvester have better adjustable performance. On this basis, an improved electromechanical coupled analytical model of continuum is proposed which can be solved by the Runge-Kutta algorithm and the influence of different factors (the mass and spring stiffness of the resonator, as well as the electromechanical coupling coefficient, electromagnetic coupling coefficient, magnet mass and magnetic flux) on the output are analyzed. According to the prototype of the vibration energy harvester developed, an experimental system was built. The performance of the independent and hybrid energy harvesters is evaluated by experimental and analytical methods. The peak output voltage of the piezoelectric part was about 4 times that of the electromagnetic part. The peak output current of the electromagnetic part is about 30 times that of the piezoelectric part. The study results show that the proposed new hybrid vibration energy harvester can achieve a wider frequency range and multimodal vibration energy harvesting. In addition, the bandwidth and power of the harvester can be dynamically adjusted by changing the resonator or electromechanical coupling coefficient, and the bandwidth of the harvester can also be adjusted by changing the quality and characteristics of the magnet.