• Title/Summary/Keyword: optimal harvesting

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Stability and Optimal Harvesting in Lotka-Volterra Competition Model for Two-species with Stage Structure

  • Al-Omari, J.F.M.
    • Kyungpook Mathematical Journal
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    • v.47 no.1
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    • pp.31-56
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    • 2007
  • In this paper, we consider a delay differential equation model of two competing species with harvesting of the mature and immature members of each species. The time delay in the model represents the time from birth to maturity of that species, which appears in the adults recruitment terms. We study the dynamics of our model analytically and we present results on positivity and boundedness of the solution, conditions for the existence and globally asymptotically stable of equilibria, a threshold of harvesting, and the optimal harvesting of the mature populations of each species.

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A BIOECONOMIC MODEL OF A RATIO-DEPENDENT PREDATOR-PREY SYSTEM AND OPTIMAL HARVESTING

  • Kar T.K.;Misra Swarnakamal;Mukhopadhyay B.
    • Journal of applied mathematics & informatics
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    • v.22 no.1_2
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    • pp.387-401
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    • 2006
  • This paper deals with the problem of a ratio-dependent prey- predator model with combined harvesting. The existence of steady states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been considered. The problem of optimal harvest policy is then solved by using Pontryagin's maximal principle.

Duality in an Optimal Harvesting Problem by a Nonlinear Age-Spatial Structured Population Dynamic System

  • Kim, Yong-Kuk;Lee, Mi-Jin;Jung, Il-Hyo
    • Kyungpook Mathematical Journal
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    • v.51 no.4
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    • pp.353-364
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    • 2011
  • Duality in the optimal harvesting for a nonlinear age-spatial structured population dynamic model is studied in the framework of optimal control problem. In this paper the duality theory that displays the conjugacy of the primal problem is established and an application is given. Duality theory plays an important role in both optimization theory and methodology and the results may be applied to a realistic biological system on the point of optimal harvesting.

Germination Percentages of Different Types of Sweet Corn in Relation to Harvesting Dates

  • Lee, Myoung-Hoon
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.45 no.1
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    • pp.55-58
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    • 2000
  • Germination of sweet and super sweet corn is lower than normal corn due to the higher sugar and lower starch contents of kernels. Sweet corn seeds are easily deteriorated in the field under the unfavorable condition, therefore it is important to identify the optimal harvesting time for seed production. This trial was conducted to investigate the responses of germination percentage of shrunken-2(sh2), brittle(bt), sugary(su), and sugary enhancer(se) hybrids in relation to harvesting dates. Eight hybrids of four different gene sweet corns were harvested at 15, 20, 25, 30, 35, 40, 45, and 50 days after silking(DAS). Germination test was performed using paper towel method. Mean germination percentages across eight hybrids showed the highest value at 45 DAS. There were significant differences among genes and within gene for germination. Shrunken-2 hybrid Mecca was higher than su hybrids for germination, indicating that sh2 would not be poorer than su Late harvesting beyond the optimal harvesting date might not be desirable because of more lodging and ear rots. Theoretical optimal harvesting date estimated from the regression equation was 40.9 DAS, however, practical date for harvesting would be a few days later than the estimated date if seedling vigor might be considered. Kernel dry weight per ear showed similar response to germination. Regression equation showed the highest kernel dry weight at 40.7 DAS. Significant correlations between kernel dry weight and germination were observed, impling that kernel dry matter accumulation would be an important factor for germination.

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Estimating Optimal Harvesting Production of Yellow Croaker Caught by Multiple Fisheries Using Hamiltonian Method (해밀토니안기법을 이용한 복수어업의 참조기 최적어획량 추정)

  • Nam, Jong-Oh;Sim, Seong-Hyun;Kwon, Oh-Min
    • The Journal of Fisheries Business Administration
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    • v.46 no.2
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    • pp.59-74
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    • 2015
  • This study aims to estimate optimal harvesting production, fishing efforts, and stock levels of yellow croaker caught by the offshore Stow Net and the offshore Gill Net fisheries using the current value Hamiltonian method and the surplus production model. As analyzing processes, firstly, this study uses the Gavaris general linear model to estimate standardized fishing efforts of yellow croaker caught by the above multiple fisheries. Secondly, this study applies the Clarke Yoshimoto Pooley(CY&P) model among the various exponential growth models to estimate intrinsic growth rate(r), environmental carrying capacity(K), and catchability coefficient(q) of yellow croaker which inhabits in offshore area of Korea. Thirdly, the study determines optimal harvesting production, fishing efforts, and stock levels of yellow croaker using the current value Hamiltonian method which is including average landing price of yellow croaker, average unit cost of fishing efforts, and social discount rate based on standard of the Korean Development Institute. Finally, this study tries sensitivity analysis to understand changes in optimal harvesting production, fishing efforts, and stock levels of yellow croaker caused by changes in economic and biological parameters. As results drawn by the current value Hamiltonian model, the optimal harvesting production, fishing efforts, and stock levels of yellow croaker caught by the multiple fisheries were estimated as 19,173 ton, 101,644 horse power, and 146,144 ton respectively. In addition, as results of sensitivity analysis, firstly, if the social discount rate and the average landing price of yellow croaker continuously increase, the optimal harvesting production of yellow croaker increases at decreasing rate and then finally slightly decreases due to decreases in stock levels of yellow croaker. Secondly, if the average unit cost of fishing efforts continuously increases, the optimal fishing efforts of the multiple fisheries decreases, but the optimal stock level of yellow croaker increases. The optimal harvest starts climbing and then continuously decreases due to increases in the average unit cost. Thirdly, when the intrinsic growth rate of yellow croaker increases, the optimal harvest, fishing efforts, and stock level all continuously increase. In conclusion, this study suggests that the optimal harvesting production and fishing efforts were much less than actual harvesting production(35,279 ton) and estimated standardized fishing efforts(175,512 horse power) in 2013. This result implies that yellow croaker has been overfished due to excessive fishing efforts. Efficient management and conservative policy on stock of yellow croaker need to be urgently implemented.

Energy Harvesting Efficiency Enhancement by Optimal Design of PZT and Electric System (PZT 시스템과 전기 시스템의 최적 설계를 통한 Energy Harvesting 효율 향상)

  • Oh, Jae-Eung;Kim, Jin-Su;Jeong, Un-Chang;Yoon, Jung-Min;Roh, Jeong-Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.925-926
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    • 2014
  • The purpose of this study is intended to improve the efficiency of energy harvesting through the optimal design of the PZT system and the electrical system. To improve the efficiency of energy harvesting, it is necessary to increase the output voltage generated from the PZT. In this study, first the mounting position and shape of the PZT which is attached to the cantilever were optimized. Second electric circuit was optimized by using a series connection of a circuit and the electrical resonance frequency. As a result, we improve the output voltage about 5V.

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Optimal vibration energy harvesting from nonprismatic piezolaminated beam

  • Biswal, Alok R;Roy, Tarapada;Behera, Rabindra K
    • Smart Structures and Systems
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    • v.19 no.4
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    • pp.403-413
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    • 2017
  • The present article encompasses a nonlinear finite element (FE) and genetic algorithm (GA) based optimal vibration energy harvesting from nonprismatic piezo-laminated cantilever beams. Three cases of cross section profiles (such as linear, parabolic and cubic) are modelled to analyse the geometric nonlinear effects on the output responses such as displacement, voltage, and power. The simultaneous effects of taper ratios (such as breadth and height taper) on the output power are also studied. The FE based nonlinear dynamic equation of motion has been solved by an implicit integration method (i.e., Newmark method in conjunction with the Newton-Raphson method). Besides this, a real coded GA based constrained optimization scheme has also been proposed to determine the best set of design variables for optimal harvesting of power within the safe limits of beam stress and PZT breakdown voltage.

Changes in the Compound and Bioactivity of Suaeda japonica Makino Extract by Different Harvesting Time

  • Choi, Ji-Hye;Lee, Sung-Gyu;Kang, Hyun
    • Biomedical Science Letters
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    • v.26 no.4
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    • pp.376-382
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    • 2020
  • This study was the change of compound and bioactivity were analyzed by different harvesting time (May, August, and November) of Suaeda japonica Makino. The total polyphenol and flavonoid contents of S. japonica were the highest at about 22.81 mg GAE/g and 4.56 mg QE/g, respectively, in the S. japonica harvested in Nov. Also, the contents of quercetin, showed the highest content in Nov harvested S. japonica. In addition, the antioxidative activity of each extract from S. japonica changed depending on harvesting time. For S. japonica harvested in Nov showed the highest DPPH and ABTS radical scavenging activity. From the NO inhibition assay, the S. japonica harvested in Nov had shown the highest anti-inflammatory effects. Therefore, consideration of the optimal harvesting time for S. japonica could be an important factor attributing to its natural antioxidant and anti-inflammatory properties and the optimal harvesting time was confirmed especially to be in Nov.

Finite-Horizon Online Transmission Scheduling on an Energy Harvesting Communication Link with a Discrete Set of Rates

  • Bacinoglu, Baran Tan;Uysal-Biyikoglu, Elif
    • Journal of Communications and Networks
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    • v.16 no.3
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    • pp.293-300
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    • 2014
  • As energy harvesting communication systems emerge, there is a need for transmission schemes that dynamically adapt to the energy harvesting process. In this paper, after exhibiting a finite-horizon online throughput-maximizing scheduling problem formulation and the structure of its optimal solution within a dynamic programming formulation, a low complexity online scheduling policy is proposed. The policy exploits the existence of thresholds for choosing rate and power levels as a function of stored energy, harvest state and time until the end of the horizon. The policy, which is based on computing an expected threshold, performs close to optimal on a wide range of example energy harvest patterns. Moreover, it achieves higher throughput values for a given delay, than throughput-optimal online policies developed based on infinite-horizon formulations in recent literature. The solution is extended to include ergodic time-varying (fading) channels, and a corresponding low complexity policy is proposed and evaluated for this case as well.

Sum-Rate Optimal Power Policies for Energy Harvesting Transmitters in an Interference Channel

  • Tutuncuoglu, Kaya;Yener, Aylin
    • Journal of Communications and Networks
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    • v.14 no.2
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    • pp.151-161
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    • 2012
  • This paper considers a two-user Gaussian interference channel with energy harvesting transmitters. Different than conventional battery powered wireless nodes, energy harvesting transmitters have to adapt transmission to availability of energy at a particular instant. In this setting, the optimal power allocation problem to maximize the sum throughput with a given deadline is formulated. The convergence of the proposed iterative coordinate descent method for the problem is proved and the short-term throughput maximizing offline power allocation policy is found. Examples for interference regions with known sum capacities are given with directional water-filling interpretations. Next, stochastic data arrivals are addressed. Finally, online and/or distributed near-optimal policies are proposed. Performance of the proposed algorithms are demonstrated through simulations.