Role In Harvesting Research Articles

Machine learning to predict the intrinsic membrane parameters in pressure retarded osmosis for an economic salinity gradient power plant

Pressure retarded osmosis (PRO) is highly investigated in the literature as one of the blue energy techniques. The PRO membrane plays a key role in harvesting the osmotic energy from a salinity gradient resource and process optimization. Therefore, a well-selected membrane will improve the power density generated in the PRO process to meet a designed power density threshold required for an economic salinity gradient power plant. In order to select a proper membrane for the PRO process, it is crucial to know its intrinsic properties, such as the membrane water permeability, salt permeability, and structural parameters, that impact the process performance. Determining the membrane's exact intrinsic parameters in a full-scale PRO module is challenging and time-consuming, and assuming constant parameters will compromise the accuracy of the results and power generation in the PRO process. This study employs artificial neural networks and Boosting-based tree models to predict the intrinsic parameters of the PRO membrane based on the minimum theoretical power density that could be predetermined and was assumed to be 5 W/m2 in this study. The Random Forest and XGBoost algorithms demonstrate superior predictive power (R2 = 0.97) compared to the other examined machine learning algorithms. The results reveal that machine learning algorithms can provide significant predictive power for the membrane's intrinsic parameters and power density based on the input parameters. Additionally, the algorithms were used to evaluate the feature importance of each input parameter affecting the power density of the pressure retarded osmosis membrane.

Population viability analysis predicts long‐term impacts of commercial Sooty Tern egg harvesting to a large breeding colony on a small oceanic island

The over‐exploitation of wild birds and the products derived from them can be a key threat driving changes in bird species richness and abundance. However, inadequate information on harvest levels combined with irregular population monitoring often means that the role of harvesting in population decline is difficult to quantify. Historically, the pan‐tropical Sooty Tern Onychoprion fuscatus has been subjected to extensive egg harvesting, yet the role of sustained harvesting in population change and future population viability remains unclear. In this study, we used published and new estimates of key demographic rates for a large, harvested Sooty Tern population in Seychelles, western Indian Ocean, to run a series of population viability analyses. We retrospectively assess the impact of historical levels of egg harvesting, and also predict how this population may respond under different future harvesting regimes, assuming no additional environmental change. We provide evidence that egg harvesting has played a substantial role in driving the population decline of Sooty Terns to date and demonstrate that continued harvesting will probably lead to further, possibly dramatic, declines in population size. These results indicate that recent levels of egg harvesting in Seychelles are not sustainable. We also show that the life‐history strategy of Sooty Terns, including a delayed age of first breeding, means the current 2‐year local moratorium on egg harvesting is unlikely to generate an observable population‐level response in Seychelles. Instead, we recommend that the current moratorium is extended at least beyond the age of first breeding (i.e. 5 years) to support appropriate evaluation. We additionally show that harvesting Sooty Tern eggs at much lower levels, i.e. 10% of the population size, is unlikely to reverse population decline. Therefore, long‐term egg harvesting strategies require careful evaluation to maintain a balance between the social, commercial, cultural and biodiversity significance of Sooty Terns in Seychelles.

Rational control of π-conjugation and CT component in hybridized local and charge transfer molecules for high performance deep blue emitters

The ratio of locally excited (LE) and charge transfer (CT) components plays a key role in harvesting the “hot” triplet excitons through high-lying reverse intersystem crossing (hRISC) in organic light-emitting materials. Herein, two blue carbazole derivative isomers 2,7-Cz(DOFCP)2 and 3,6-Cz(DOFCP)2 were designed with A-π-D-π-A structures. The localized π-conjugation and intramolecular charge transfer components ratio was rationally varied by the substitute position of 9,9-dioctylfluorenyl (DOF) π-bridge on the carbazolyl donor unit. Both of the emitters exhibited hybridized local and charge transfer (HLCT) characteristics, and 2,7-Cz(DOFCP)2 with prolonged localized π-conjugation nature realized a smaller energy splitting (ΔES2-T3) and higher fluorescence quantum yield. The OLEDs based on the emitters achieved deep blue and nearly standard blue electroluminescence with the CIE coordinates of (0.153, 0.063) and (0.153, 0.091), and maximum EQEs of 5.57% and 7.37% that was beyond the conventional fluorescence devices, respectively. This work would provide insights for promoting the luminescence performance of the HLCT molecules by adjusting the LE/CT proportion in the excited states.

Energy Recovery from Exhaust Gas of Diesel and Petrol Engine by Turbo-electric Generator

A turbo-electric generator has been placed on the exhaust port of the petrol and diesel engines to investigate the possibility of recovering energy from the exhaust gas. Turbo-electric generator is a combination of a turbocharger and a generator. The aim of the study is to find the possibility and effectiveness of the turbo-electric generator for recovering the energy from the exhaust gas of an engine. The test has been conducted on the two engines, i.e. first one is TD 202 small test engine bed (diesel engine) and another one is Honda CG125 cc (petrol engine) motorcycle. Two types of motor i.e. DC motor and AC motor have been used as generators by altering the way a motor works. Firstly, a DC motor is used as a generator in the turbo-electric generator for both test engines. The results show that turbo-electric generator recover less than 1% energy of the exhaust gas for both engines when a DC motor is used as a generator (TD 202 and Honda CG125 cc motorcycle). But in case of Honda CG125 cc motorcycle, the percentage of recovering energy is comparatively higher than the TD 202 test engine. The experiment is further extended by using an AC motor as a generator only for the Honda CG125 cc motorcycle. The results show better energy recovering from exhaust gas through turbo-electric generator, which is more than 1% of exhaust gas. The results reveal that the engine speed and the mass flow rate of the exhaust gas play a major role in harvesting the energy from the exhaust gas. Moreover, it is found that the turbo-electric generator module provides good efficiency when an AC motor is used as a generator in the module. The experimental results have been compared with available literature.

The role of harvesting in population control in the presence of correlated noise sources

In this paper, we compare the role of constant and Michaelis-Menten type harvesting in single species population control in presence of correlated noise sources. Our aim is to determine a statistical correlation between the noises in the model parameters and population size. The characteristic time scale over which the population size of prey and predator varies are very much different, this fact justifies to consider a single species model as the predator population can be chosen to be constant within the generation time of prey. Steady state probability distributions and stationary potentials of the population are determined by Fokker-Planck equations. Stochastic bifurcation analysis and mean first passage times have been computed. Noise induced critical transitions are observed depending on the strength of the noises. The extinction possibility of population in stochastic control with Michaelis-Menten type harvesting is higher than the constant harvesting. One of our key findings is the transition from bistable to tristable state for weak noises. Another valuable finding is the noise enhanced stability phenomenon for negatively correlated noises. Constant rate of harvesting is better in deterministic case whereas Michaelis-Menten type harvesting is better in stochastic case to reduce population size. The obtained results may be helpful to understand toxin producing phytoplankton blooms and its control in marine ecosystem. Moreover, the study can be useful to explain wild prey population outbreak or extinction in forest.

Wastewater substrates in microbial fuel cell systems for carbon-neutral bioelectricity generation: An overview

Increasing environmental pollution along with fossil fuel depletion is demanding essential energy solutions. Microbial fuel cell (MFC) utilize waste resources containing biodegradable matter that plays a vital role in green “carbon–neutral” bioenergy production. MFC technology involves the multidisciplinary approach of microbiology, electrophysiology, electrochemistry, and process engineering, etc., with vast opportunities and challenges. The substrate is one of the most significant factors influencing the performance of MFC. The shift from synthetic and simple substrates towards different types of industrial wastewater with a higher level of organic matter positively impacts a crucial role in harvesting “green electricity” in MFCs. Some of the ultimate challenges and future perspectives on the energy recovery from the effluents utilized in MFCs are witnessed along with the technological progression over the years.

The Rasūlids and the Bountiful Sea: Marine Resources, State Control, and Maritime Culture in the Southern Red Sea and the Gulf of Aden (626/1229‒854/1454)

Abstract Relying on textual, ethnographic, and environmental scholarship on Yemen and the comparative insights of research into fisheries in the premodern Mediterranean world, the present study surveys the types of marine resources that appear across a wide range of literary and documentary sources pertaining to Yemen during the reign of the Rasūlids from the early 7th/13th to the mid-9th/15th century. Although Rasūlid-generated texts pay relatively scant attention to fishing, they clearly demonstrate the interest of the Rasūlid state in both the subsistence and commercial economy that fishermen procured. Moreover, when combined with the testimony of travelers and chroniclers and of iconography on a series of Rasūlid coins from the port city of Aden, these sources shed light on the inclusion of fish in Yemeni non-elite and elite diets, the place and roles of fisherfolk in Yemeni society, the maritime symbolism current in Rasūlid times, and ultimately the relationship between shores and inland centers of Rasūlid power. In aggregate this material suggests that the Rasūlid state maintained a symbiotic political and cultural relationship with fishing communities, which had direct access to and the primary role in harvesting and processing the resources in question, yet remain in the shadows of recorded history.

Efficient platinum harvesting of MOF-derived N-doped carbon through cathodic cyclic voltammetry for hydrogen evolution

Although platinum has been recognized as one of the most efficient catalysts for hydrogen evolution reaction, chemically compatible supports are still needed to address its instability issue. Herein, we demonstrate a rational design and synthesis of a N-doped graphitic carbon material from a N-rich MOF as the superior support for dispersion of platinum. The in-situ doped N atoms play an important role in harvesting and anchoring platinum through the electrochemical process. Compared with carbon nanotubes and graphene oxide, the as-prepared carbon material exhibits exceptional HER performance after platinum decoration with low onset overpotential, small Tafel slope, and high stability in acidic solution. DFT calculations indicate that the superior electrocatalytic activity and high platinum harvesting efficiency is due to the strong interaction between doped N sites and platinum atom, which facilitates the electron transport and hydrogen evolution process. This work would provide some new ideas for designing and fabricating high active and long-time durable HER catalysts with lower platinum loading.

Roles of CpcF and CpcG1 in Peroxiredoxin-Mediated Oxidative Stress Responses and Cellular Fitness in the Cyanobacterium Synechocystis sp. PCC 6803.

As a component of the photosynthetic apparatus in cyanobacteria, the phycobilisome (PBS) plays an important role in harvesting and transferring light energy to the core photosynthetic reaction centers. The size, composition (phycobiliprotein and chromophore), and assembly of PBSs can be dynamic to cope with tuning photosynthesis and associated cellular fitness in variable light environments. Here, we explore the role of PBS-related stress responses by analyzing deletion mutants of cpcF or cpcG1 genes in Synechocystis sp. PCC 6803. The cpcF gene encodes a lyase that links the phycocyanobilin (PCB) chromophore to the alpha subunit of phycocyanin (PC), a central phycobiliprotein (PBP) in PBSs. Deletion of cpcF (i.e., ΔcpcF strain) resulted in slow growth, reduced greening, elevated reactive oxygen species (ROS) levels, together with an elevated accumulation of a stress-related Peroxiredoxin protein (Sll1621). Additionally, ΔcpcF exhibited reduced sensitivity to a photosynthesis-related stress inducer, methyl viologen (MV), which disrupts electron transfer. The cpcG1 gene encodes a linker protein that serves to connect PC to the core PBP allophycocyanin. A deletion mutant of cpcG1 (i.e.,ΔcpcG1) exhibited delayed growth, a defect in pigmentation, reduced accumulation of ROS, and insensitivity to MV treatment. By comparison, ΔcpcF and ΔcpcG1 exhibited similarity in growth, pigmentation, and stress responses; yet, these strains showed distinct phenotypes for ROS accumulation, sensitivity to MV and Sll1621 accumulation. Our data emphasize an importance of the regulation of PBS structure in ROS-mediated stress responses that impact successful growth and development in cyanobacteria.

Design, Performance, and Application of Thermoelectric Nanogenerators.

Thermal energy harvesting from the ambient environment through thermoelectric nanogenerators (TEGs) is an ideal way to realize self-powered operation of electronics, and even relieve the energy crisis and environmental degradation. As one of the most significant energy-related technologies, TEGs have exhibited excellent thermoelectric performance and played an increasingly important role in harvesting and converting heat into electric energy, gradually becoming one of the hot research fields. Here, the development of TEGs including materials optimization, structural designs, and potential applications, even the opportunities, challenges, and the future development direction, is analyzed and summarized. Materials optimization and structural designs of flexibility for potential applications in wearable electronics are systematically discussed. With the development of flexible and wearable electronic equipment, flexible TEGs show increasingly great application prospects in artificial intelligence, self-powered sensing systems, and other fields in the future.

Simultaneous recovery of microalgae, ammonium and phosphate from simulated wastewater by MgO modified diatomite

In this study, MgO modified diatomite (MgO-D) was used for recovery of microalgae (Chlorella pyrenoidosa FACHB-9), NH4+-N and phosphate from wastewater. The effects of adsorbent dosage, solution pH, contact time, and coexisting substances were investigated. The results showed that MgO-D exhibited excellent recovery efficiency for microalgae, NH4+-N and phosphate in a wide pH range of 3.0–9.0. With initial pH = 8.0, MgO-D = 0.5 g/L and reaction time = 2 h, the recovery efficiencies of microalgae, NH4+-N and phosphate were 182.04 mg/g, 63.3 mg/g, 121.07 mg/g, respectively. Coexisting organic matters inhibited the recovery of microalgae, NH4+-N and phosphate in the order of alginate > humic acid > acetic acid. When in proper concentration range, NH4+-N and phosphate were preferentially recovered by MgO-D through struvite precipitation, and then the charge neutralization of hydroxylated Mg(OH)2 and sweeping of struvite precipitation played an important role in harvesting of microalgal cells. This study shows new guidelines and useful methods for the simultaneous recovery of microalgae, NH4+-N and phosphate from wastewater.

Role of harvesting in controlling chaos and disease propagation in predator-prey system with disease in prey

The paper explores an eco-epidemiological model with harvesting in the species and the disease is circulating in the prey population. The curiosity of this paper is to consider the role of harvesting on chaotic dynamics. We perform the local and global stability analysis of the equilibrium points and the Hopf bifurcation analysis around the interior equilibrium point. Further we pay attention to the direction of Hopf Bifurcation. Our numerical simulations reveal that the three species eco-epidemiological system shows chaos in low level of infection. It is observed that when force of infection increases chaos becomes stable. We conclude that chaotic dynamics can be controlled by the harvesting parameter as well as the force of infection.We apply basic tools of non-linear dynamics such as Poincare section and maximum Lyapunov exponent to identify chaotic behaviour of the system.

Web-Based Collaborative Systems and Harvesting the Collective Intelligence in Business Organizations

The major purpose of this article is to empirically explore the role of web-based collaborative systems in harvesting the dimensions of collective intelligence and the expected outcomes. A questionnaire survey was developed to collect data from 29 firms across all industries with a sample of 239 respondents. Structural Equation Modeling, using Smart PLS was conducted to analyze the data. The results indicated that web-based collaborative systems play a significant role in harvesting the dimensions of collective intelligence, including collective cognition, shared memory, collective problem solving, knowledge sharing, and collective learning. The results also revealed the significant impact of web-based collective intelligence on the sense and response capability and on the quality and morality of organizations' decisions. In addition, the article reveals the significant impacts of BI tools and relationship quality on the role of web-based CI in achieving the expected outcomes.

Harvest the potential of massive MIMO with multi-layer techniques

Massive MIMO is envisioned as a promising technology for 5G wireless networks due to its high potential to improve both spectral and energy efficiency. Although the massive MIMO system is based on innovations in the physical layer, the upper layer techniques also play important roles in harvesting the performance gains of massive MIMO. In this article, we begin with an analysis of the benefits and challenges of massive MIMO systems. We then investigate the multi-layer techniques for incorporating massive MIMO in several important network deployment scenarios. We conclude this article with a discussion of open and potential problems for future research.

Some Studies on Thermal Performance of Solar Cooking System

Solar cooking is an important area of present Indian research scenario. It is high time to find an alternate energy source for highly populated country like India where the demands for energy source has drastically increased for the last two decades. Solar energy is playing a major role in fulfilling the needs of the researchers where people have already started to harvest the free and ample energy source effectively. The needs of thermal energy for cooking in India is huge and people have spent a large amount of thermal energy for cooking. Solar cooking hits even villages of India now a days and many people have already started to utilize the solar energy for cooking. The efficiency of the solar collector plays a vital role in harvesting the free energy effectively; meanwhile the cooking vessels also play a major role in utilizing the heat energy to cook the food efficiently. In this research work, experimental investigation is carried out to study the effectiveness of the solar collector and the thermal efficiency of the cooking vessels. The traditional food of South Indian's like rice and chicken have been cooked with the help of solar cooker on a sunny day at Salem, Tamil Nadu, India. The time taken to cook food along with the effect of solar irradiation is also studied in this research work. Based on the experimental results it is also verified that the recommended cooking time for the chicken, considering food safety, was found to be 80 minutes cooked at an average solar irradiation of 540 W/m2. Time required to cook the different food items have been calculated by means of conventional method and the calculated time was compared with the experimental values. Both the results, well matched each other and finally the solar cooker efficiency is calculated from the deviation of the results as 26.06%.

The role of harvest, predators, and socio-political environment in the dynamics of the Taimyr wild reindeer herd with some lessons for North America

The Taimyr wild reindeer herd, i.e., caribou (Rangifer tarandus), is one of the most important wildlife resources in the Russian Far North and may constitute the largest migratory Rangifer herd in the world. Over the last 60 years the herd has undergone a recovery from low numbers in the 1940s, reaching high densities by 1970 that concerned wildlife managers and domestic husbandry herds, with an 11.7% annual growth rate. At that time an aggressive commercial harvest of the herd was implemented, and organized wolf control was initiated with the goal of stabilizing herd numbers and injecting needed economic activity into the region. These actions dampened the rate of increase throughout the 1970s and 1980s to a 3.0% annual growth rate. From 1991, after the collapse of the Soviet Union and the loss of financial capability to sustain the commercial harvest and continue wolf control, the population again increased at a 5.6% annual growth rate, until peaking in 2000 at just more than 1 million animals. Since 2000 the herd has been in decline; harvesting, primarily unregulated, has increased; the wolf population has increased; and range conditions have deteriorated. Understanding what has occurred in the Taimyr range can provide North American managers with valuable lessons in understanding the large migratory herds on this continent, especially given that the social and political situation in Russia enabled intensive management, i.e., harvest and wolf control, that may not be able to be duplicated in North America.

Phenotypic and reproductive variation in female white-tailed deer: The role of harvest and environment

Animal density and stochastic environmental events affect physical development and recruitment of cervids. Biologists who manage cervid populations based on a density-dependent paradigm may need to also consider environmental effects. We analyzed 12- to 25-year time series of 3 harvested white-tailed deer populations in Mississippi to determine the relative influence of harvest and environmental factors on female reproduction and phenotypic quality. Using simple and multiple linear regression, we related body mass of 1.5-, 2.5-, and ≥3.5-year females, and 2.5- and ≥3.5-year percent lactation to variables representing deer harvest, growing season precipitation and temperatures, high-quality agronomic plantings, and flooding events. Response across populations varied greatly, with harvest variables explaining most, some, or no variation in body mass and percent lactation. Biologists should consider the potential influence of environmental factors on phenotypic and reproductive variation when making management decisions. © 2012 The Wildlife Society.

Harvest and dynamics of duck populations

AbstractThe role of harvest in the dynamics of waterfowl populations continues to be debated among scientists and managers. Our perception is that interested members of the public and some managers believe that harvest influences North American duck populations based on calls for more conservative harvest regulations. A recent review of harvest and population dynamics of North American mallard (Anas platyrhynchos) populations (Pöysä et al. 2004) reached similar conclusions. Because of the importance of this issue, we reviewed the evidence for an impact of harvest on duck populations. Our understanding of the effects of harvest is limited because harvest effects are typically confounded with those of population density; regulations are typically most liberal when populations are greatest. This problem also exists in the current Adaptive Harvest Management Program (Conn and Kendall 2004). Consequently, even where harvest appears additive to other mortality, this may be an artifact of ignoring effects of population density. Overall, we found no compelling evidence for strong additive effects of harvest on survival in duck populations that could not be explained by other factors. © 2012 The Wildlife Society.

The role of harvesting in age-structured populations: Disentangling dynamic and age truncation effects

Understanding the processes generating fluctuations of natural populations lies at the very heart of academic ecology. It is also very important for applications such as fisheries management and pest control. We are interested in the effect of harvesting on population fluctuations and for that purpose we develop and analyze an age-structured model where recruitment is a stochastic process and the adult segment of the population is harvested. When a constant annual harvest is taken the coefficient of variation of the adult population increases for most parameter values due to the age truncation effect, i.e. an increased variability in a juvenescent population due to the removal of older individuals. However, if a constant proportion of the adults is harvested the age truncation effect is sometimes counteracted by a stabilizing dynamic effect of harvesting. Depending on parameter values mirroring different life histories, proportional harvest can either increase or decrease the relative fluctuations of an exploited population. When there is a demographic Allee effect the ratio of juveniles to adults may actually decrease with harvesting. We conclude that, depending on life history and harvest strategy, harvesting can either reinforce or dampen population fluctuations due to the relative importance of stabilizing dynamic effects and the age truncation effect. The strength of the latter is highly dependent on the fished population’s endogenous, age-structured dynamics. More specifically, we predict that populations with strong and positively autocorrelated dynamics will show stronger age truncation effect, a testable prediction that offers a simple rule-of-thumb assessment of a population’s vulnerability to exploitation.

New perspectives on harvesting as one driver of ecosystem dynamics

New perspectives on harvesting as one driver of ecosystem dynamics