Modes Of Harvesting Research Articles

Electrochemical harvesting of Chlorella sp.: Electrolyte concentration and interelectrode distance

Two modes of electrochemical harvesting for microalgae were investigated in the current work. A sacrificial anode (aluminum) was used to study the electrocoagulation-flotation process, and a nonsacrificial anode (graphite) was used to investigate the electroflotation process. The study inspected the effect of chloride ions concentration and the interelectrode distance on the performance of the electrochemical harvesting processes. The results demonstrated that both electrodes achieved maximum harvesting efficiency with a 2 g/L NaCl concentration. Interestingly, by increasing the NaCl concentration to 5 g/L, the harvesting efficiency reduced dramatically to its lowest value. Generally, the energy consumption decreased with increasing of NaCl concentration. Moreover, the energy consumption achieved with aluminum anodes is lower than that achieved with graphite. However, by increasing the gap between the electrodes from 15 mm to 30 mm, the time required to achieve the maximum efficiency doubled, and energy consumption increased consequently.

Dynamic Domains of Antarctica: A Design Model of Global Commons in Sync with Planetary Metabolism

AbstractAs part of a recent MArch Landscape Urbanism thesis project at the Architectural Association (AA) in London, Daniel Kiss and Swadheet Chaturvedi investigated the food chains that impinge on Antarctica, which are deeply intertwined with the health of our planet. The authors zero in, for example, on the fishing of krill, illustrating its domains and positing dynamic protections for sustainable modes of harvesting.

Diachronic and Cultural Variations in Chukchi Ethnobotany

Although the ethnoecology of the Chukchi has long been the focus of researchers, a systemic description informing the history of plant use, including local names or modes of harvesting and preparation, suitability for different ages, and different occasions, is largely lacking. C. H. Merck provided the first account of food plants at the end of the 18th century, during the Billings-Sarychev expedition, however, the first information regarding traditionally used medicinal plants was published only recently, after centuries of contact. During our 2014-2015 fieldwork, we interviewed 56 Chukchi people in the Chukotskii and Iultinskii districts of Chukotka to collect material on the most common local plants. We also gathered data on Chukchi ethnobotany from all available published sources. Slight differences were observed between maritime and reindeer Chukchi, with the former relying more on plant resources. Access limitations (e.g., algae) are reduced by exchanges between the two groups. The decline in the consumption of roots gathered from vole nests (peɬqumret) is compensated by an increase in berry harvesting (e.g., cloudberry, crowberry, bog blueberry, and lingonberry). Our results also show that the main medical uses are aimed at disease prevention, though some are borrowed from scientific pan-Russian herbal medicine popularized during the Soviet period.

Combine Harvester Fuel Consumption and Air Pollution Reduction

Agricultural production has a major impact on the environment. Indeed, the emissions from agricultural machinery have a significantly negative impact on ambient air, thereby contributing to Climate Change. This study analyses combine harvesters and justifies their optimization in order to increase resource efficiency as well as reduce any negative impact on the environment. Data from 90 combine harvesters in Lithuania and Latvia from 2016 to 2018 is collected using telematics, and the parameters that directly influence engine exhaust emissions are analyzed, such as operation time, grain unloading method, fuel consumption, and auto-steering, according to the engine-operating modes of harvesting, transportation, and idling. Statistically reliable strong correlations can be found between harvesting time and idling time, as well as between fuel consumption during harvesting and idling modes. On average, roughly 20% of the operating time consists of idling and roughly 15% of transportation; moreover, roughly 14% of the diesel fuel is used per year in the aforementioned engine modes. In addition, the auto-steering function enables the efficient use of diesel fuel (average cost per combine harvester is reduced by 0.2 t year⁻¹), thereby reducing air pollution (pollution per combine harvester is reduced on average by 0.6 t year⁻¹). The results suggest telematics system data can be effectively used for data analysis, problem identification, and decision-making with respect to pollution prevention and optimizing combine harvester operation. Graphical Abstract

Direct Electricity Generation Mediated by Molecular Interactions with Low Dimensional Carbon Materials—A Mechanistic Perspective

AbstractNext‐generation off‐the‐grid electronic systems call for alternative modes of energy harvesting. The past two decades have witnessed the evolution of a wide spectrum of low dimensional carbon materials with extraordinary physical and chemical properties, ideal for microscale electrical energy storage and generation. Tremendous progress has been made in harnessing the energy associated with the interactions between these nanostructured carbon substrates and the surrounding molecular phases, subsequently converting them into useful electricity. This review summarizes the important theoretical and experimental milestones the field has reached to date, and further classifies these energy harvesting processes based on underlying physics, into five mechanistically distinct classes—phonon coupling, Coulombic scattering, electrokinetic streaming, asymmetric doping, and capacitive discharging. With a special mechanistic focus, the authors hope to resolve the fundamental attributes shared by this diverse array of molecular scale energy harvesting schemes, offer perspectives on key challenges, and ultimately establish design principles that guide further device optimization.

Broadband dual phase energy harvester: Vibration and magnetic field

Broadband mechanical energy harvesting implies stable output power over a wide range of source frequency. Here we present a cost-effective solution towards achieving broadband response by designing a magnetically coupled piezoelectric energy harvester array that exhibits a large power density of 243 μW/cm3 g2 at natural frequency and bandwidth of more than 30 Hz under 1 g acceleration. The magnetically coupled piezoelectric energy harvester array exhibits dual modes of energy harvesting, responding to both stray magnetic field as well as ambient vibrations, and is found to exhibit the output power density of 36.5 μW/cm3 Oe2 at 79.5 Hz under the ambient magnetic field while maintaining the broadband nature. The magnetically coupled piezoelectric energy harvester array was demonstrated to harvest continuous power from a rotary pump vibration, an automobile engine vibration and a parasitic magnetic field surrounding a cable of an electric kettle. These demonstrations suggest that the magnetically coupled piezoelectric energy harvester array could serve the role of a standalone power source for wireless sensor nodes and small electronic devices.

Flood pulse dynamics affects exploitation of both aquatic and terrestrial prey by Amazonian floodplain settlements

Rural populations in the tropics frequently rely on game vertebrates and fish to supply their daily protein requirements. However, few studies have quantified the environmental and socioeconomic drivers of hunting and fishing effort and the potential compensatory relationship between these extractive activities. Here, we assessed game and fish extraction by 222 semi-subsistence households from 28 villages along a major white-water tributary of Brazilian Amazonia. During the 44months study, a total of 32,114kg of game and 261,752kg of fish were harvested, amounting to an average extraction rate of 30.5±109.9gperson−1day−1 and 1519.4±1037.6gperson−1day−1 for game and fish, respectively. While 97.93±0.03% of all fishing trips resulted in fish catches, only 77.12±27.02% of the hunting forays successfully obtained at least one forest vertebrate. The flood pulse had a strong effect on both fishing and hunting activities. However, the seasonally rising floodwaters had a negative effect on fish yield and catch per unit effort (CPUE), but had a positive effect on game yields. Game yield was also an important variable explaining fish yield, indicating a strong compensatory interaction between these two forms of protein acquisition. Our results highlight the importance of considering different modes of animal protein harvesting in conservation planning and management of both forest vertebrates and aquatic organisms.

Forest fuels and potential fire behaviour 12 years after variable-retention harvest in lodgepole pine

Variable-retention harvesting in lodgepole pine offers an alternative to conventional, even-aged management. This harvesting technique promotes structural complexity and age-class diversity in residual stands and promotes resilience to disturbance. We examined fuel loads and potential fire behaviour 12 years after two modes of variable-retention harvesting (dispersed and aggregated retention patterns) crossed by post-harvest prescribed fire (burned or unburned) in central Montana. Results characterise 12-year post-treatment fuel loads. We found greater fuel load reduction in treated than untreated stands, namely in the 10- and 100-h classes (P = 0.002 and 0.049 respectively). Reductions in 1-h (P < 0.001), 10-h (P = 0.008) and 1000-h (P = 0.014) classes were greater in magnitude for unburned than burned treatments. Fire behaviour modelling incorporated the regenerating seedling cohort into the surface fuel complex. Our analysis indicates greater surface fireline intensity in treated than untreated stands (P < 0.001), and in unburned over burned stands (P = 0.001) in dry, windy weather. Although potential fire behaviour in treated stands is predicted to be more erratic, within-stand structural variability reduces probability of crown fire spread. Overall, results illustrate trade-offs between potential fire attributes that should be acknowledged with variable-retention harvesting.

Novel Spiral-Like Electrode Structure Design for Realization of Two Modes of Energy Harvesting.

A planar spiral-like electrodes (PSE) based triboelectric generator has been designed for harvesting rotary mechanical energy to translate into electricity. The performance of the PSE-triboelectric generator with different cycles of spiral-like electrode strip at different rotating speeds is investigated, which demonstrates the open-circuit voltage and short-circuit current of 470 V and 9.0 μA at rotating speed of 500 r/min with three cycles. In addition, a novel coaxially integrated multilayered PSE-triboelectric generator is built, which can enhance the output of the power effectively. The short-circuit current, the open-circuit voltage, and output power reach to 41.55 μA, 500 V, and 11.73 mW, respectively, at rotating speed of 700 r/min. The output power of the multilayered PSE-triboelectric generator can drive 200 LEDs connected in antiparallel and charge a 110 μF commercial capacitor to 6 V in 23 s. Besides, due to the spiral-like electrode structure, the PSE-generator can work simultaneously in the modes of triboelectricity and electromagnetic induced electricity by sticking a small magnet on the rotating disk. The electromagnetic induced output power reaches to 21 μW at a loading resistance of 2 Ω at a rotating rate of 200 r/min. The spiral-like electrode structure not only broadens the electrode structure design but also adds a new function to the electrode.

Microbial contamination of traditional medicinal plants sold at the Faraday muthi market, Johannesburg, South Africa

The Faraday traditional healers' trading market is the hub of the medicinal plant trade in Johannesburg, South Africa. Modes of harvesting, transporting, storage and distribution of medicinal plants render them susceptible to microbial attack, and thereby make customers, especially patients with compromised immune systems, vulnerable to infections that could increase morbidity and mortality. This study evaluated the microbial contamination on five frequently used traditional medicinal plant species sold by traders in the Faraday market. Bacterial contamination was determined using serial macro dilutions, spread plate and streak plate techniques. Fifteen bacterial contaminants were identified, the most recurrent being Pantoea sp. and five strains of Bacillus spp. (non-pathogenic). There was little variation between contamination levels of the five different traders, and the mean CFU/g per species ranged from 3.03×104 (Hypoxis sp.) to 4.22×105 (Hydnora abyssinica). While there was no overall significant levels of contamination, the CFU counts for two plant species purchased from one specific trader (viz. H. abyssinica and Acacia xanthophloea) exceeded maximum acceptable contamination limits set by the World Health Organisation (i.e. ≤105 to ≤107CFU/g). The levels of contamination varied greatly between the commercially available over the counter product and the plant samples investigated. The microbial types are predominantly opportunistic pathogens. The implementation of good processing practices therefore clearly influences the quality and safety of medicinal products, especially regarding microbial contamination. It is evident that policies and regulations need to be developed and implemented in order to address possible contamination by opportunistic pathogens.

Wireless Information Transfer with Opportunistic Energy Harvesting

Energy harvesting is a promising solution to prolong the operation of energy-constrained wireless networks. In particular, scavenging energy from ambient radio signals, namely wireless energy harvesting (WEH), has recently drawn significant attention. In this paper, we consider a point-to-point wireless link over the narrowband flat-fading channel subject to time-varying co-channel interference. It is assumed that the receiver has no fixed power supplies and thus needs to replenish energy opportunistically via WEH from the unintended interference and/or the intended signal sent by the transmitter. We further assume a single-antenna receiver that can only decode information or harvest energy at any time due to the practical circuit limitation. Therefore, it is important to investigate when the receiver should switch between the two modes of information decoding (ID) and energy harvesting (EH), based on the instantaneous channel and interference condition. In this paper, we derive the optimal mode switching rule at the receiver to achieve various trade-offs between wireless information transfer and energy harvesting. Specifically, we determine the minimum transmission outage probability for delay-limited information transfer and the maximum ergodic capacity for no-delay-limited information transfer versus the maximum average energy harvested at the receiver, which are characterized by the boundary of so-called outage-energy region and region, respectively. Moreover, for the case when the channel state information (CSI) is known at the transmitter, we investigate the joint optimization of transmit power control, information and energy transfer scheduling, and the receiver's mode switching. The effects of circuit energy consumption at the receiver on the achievable rate-energy trade-offs are also characterized. Our results provide useful guidelines for the efficient design of emerging wireless communication systems powered by opportunistic WEH.

Ecological consequences of hunting, trapping, and fishing on the Novaya Zemlya archipelago

The current status of the biotic resources that support hunting, trapping, and fishing activities on Novaya Zemlya is reviewed and the impacts of these activities on their populations assessed. The impact of changing technologies and modes of harvesting on the ecology of animal populations is illustrated beginning with traditional activities of Pomors and Nenets in the 16th century, extending through the activities of Norwegian whaling and other operations in the second half of the 19th century, and the massive, year‐round organized harvesting during the early Soviet period. Translated by Edward Torrey, Alexandria, VA from: Geografiya i prirodnyye resursy 1999, No. 2, pp. 74–79.

COPATH—a spreadsheet model for the estimation of carbon flows associated with the use of forest resources

The forest sector plays a key role in the global climate change process. A significant amount of net greenhouse gas emissions emanate from landuse changes, and the sector offers a unique opportunity to sequester carbon in vegetation, detritus, soils and forest products. However, the estimates of carbon flows associated with the use of forest resources have been quite imprecise. This paper describes a methodological framework—COPATH—which is a spreadsheet model for estimating carbon emissions and sequestration from deforestation and harvesting of forests. The model has two parts, the first estimates carbon stocks, emissions and uptake in the base year, while the second part forecasts future emissions and the uptake under various scenarios. The forecast module is structured after the main modes of forest conversion, i.e. agriculture, pasture, forest harvesting and other land uses. The model can be used by countries which may not possess an abundance of pertinent data, and allows for the use of forest inventory data to estimate carbon stocks. The choice of the most likely scenario procides the country with a carbon flux profile necessary to formulate GHG mitigation strategies.