A dynamic programming algorithm for optimization of uneven-aged forest stands

1994 ◽  
Vol 24 (9) ◽  
pp. 1758-1765 ◽  
Author(s):  
David J. Anderson ◽  
B. Bruce Bare
Keyword(s):  
Dynamic Programming ◽  
Interest Rates ◽  
Net Present Value ◽  
Initial Conditions ◽  
Dynamic Programming Algorithm ◽  
Basal Area ◽  
Management Problem ◽  
Present Value ◽  
Stand Management ◽  
The Impact

A deterministic dynamic programming formulation of the transition uneven-aged stand management problem is presented. Using a previously published northern hardwoods growth model, a forward recursive, discrete, two-state problem that maximizes the net present value of harvested trees at each stage is developed. State variables represent the total number of trees and the total basal area per acre. A neighborhood storage concept previously published is used to reduce the number of states considered at each stage. Two harvest allocation rules are used to assign the harvested basal area to individual diameter classes. Terminal end point conditions and stage to stage sustainability are not required. Results from four base runs of the model are presented and compared with previously published results. Each run produces significantly different optimal paths, with one showing a higher net present value than any previously published. Sensitivity runs illustrate the impact of changes in interest rates, width of neighborhood storage class, and initial conditions. Dynamic programming offers promise for analyzing uneven-aged stand management problems.

scholarly journals A neuro-dynamic programming approach to the optimal stand management problem

2017 ◽  
Vol 47 (6) ◽  
pp. 808-816
Author(s):  
Jules Comeau ◽  
Eldon Gunn
Keyword(s):  
Dynamic Programming ◽  
Growth Models ◽  
Growth Dynamics ◽  
Basal Area ◽  
Programming Approach ◽  
Management Problem ◽  
Continuous Variables ◽  
Indicator Variable ◽  
Stand Management ◽  
Commercial Thinning

Some ideas of neuro-dynamic programming (NDP) are illustrated by considering the problem of optimally managing a forest stand under uncertainty. Because reasonable growth models require state information such as height (or age), basal area, and stand diameter, as well as an indicator variable for treatments that have been performed on the stand, they can easily lead to very large state spaces that include continuous variables. Realistic stand management policies include silvicultural options such as pre-commercial and commercial thinning as well as post-harvest treatments. We are interested in problems that are stochastic in their basic growth dynamics, in market prices, and in disturbances, ranging from insects to fire to hurricanes. NDP algorithms are appropriate for problems with large dimensions that may lack a simple model of dynamics and stochastic processes. This paper looks at applying these ideas in the context of a multispecies model. Results show that policies obtained using NDP are optimal within a 95% confidence interval or better. The set of states and controls incorporated into our NDP model allows us to develop optimal policies with a level of detail not typically seen in the forestry literature.

scholarly journals Harvendusraiete tasuvuse analüüs ja pikaajalise mõju simulatsioonid Järvselja õppe- ja katsemetskonnas

2020 ◽  
Vol 72 (1) ◽  
pp. 54-63
Author(s):  
Paavo Kaimre ◽  
Priit Vellak ◽  
Meelis Teder
Keyword(s):  
Forest Management ◽  
Net Present Value ◽  
Net Income ◽  
Wood Production ◽  
Present Value ◽  
Management Scenarios ◽  
Fuel Wood ◽  
Stand Management ◽  
Long Run ◽  
The Impact

AbstractThe results of the analysis of profitability and impact of thinning on wood production in Järvselja Training and Experimental Forest Centre are presented in the article. The profitability was assessed on the basis of harvesting income and costs of logging operations in 2015–2017. The impact of thinning on the wood production was assessed using the MOTTI simulation program. Three different scenarios for the management of the stand were compared: 1) stand management in accordance with the Finnish forest management recommendations (Tapio recommendations), 2) management according to the Estonian Forest Management Regulations and 3) stand development without thinning. The results revealed that 61 thinnings out of the 70 were profitable. The average net income from thinning was 344 euros per hectare. Fuel wood accounted for 45% and pulpwood for 30% of the harvested timber. Net present value was applied as a criterion to assess the profitability of long-term management scenarios. Considering Tapio's recommendations, the total net present value was 33% higher and following Estonian forest management rules, it was 23% higher compared to the simulations without thinning. The results indicated that thinning is economically viable in the long run. In simulations without thinning, timber production is the highest, but the net present value of management is lower compared to simulations with thinning.

scholarly journals Gas to Liquids Techno-Economics of Associated Natural Gas, Bio Gas, and Landfill Gas

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1568
Author(s):  
Federico Galli ◽  
Jun-Jie Lai ◽  
Jacopo De Tommaso ◽  
Gianluca Pauletto ◽  
Gregory S. Patience
Keyword(s):  
Natural Gas ◽  
Net Present Value ◽  
Landfill Gas ◽  
Labor Cost ◽  
Variable Cost ◽  
Selling Price ◽  
Present Value ◽  
Fischer Tropsch ◽  
Gas To Liquids ◽  
The Impact

Methane is the second highest contributor to the greenhouse effect. Its global warming potential is 37 times that of CO2. Flaring-associated natural gas from remote oil reservoirs is currently the only economical alternative. Gas-to-liquid (GtL) technologies first convert natural gas into syngas, then it into liquids such as methanol, Fischer–Tropsch fuels or dimethyl ether. However, studies on the influence of feedstock composition are sparse, which also poses technical design challenges. Here, we examine the techno-economic analysis of a micro-refinery unit (MRU) that partially oxidizes methane-rich feedstocks and polymerizes the syngas formed via Fischer–Tropsch reaction. We consider three methane-containing waste gases: natural gas, biogas, and landfill gas. The FT fuel selling price is critical for the economy of the unit. A Monte Carlo simulation assesses the influence of the composition on the final product quantity as well as on the capital and operative expenses. The Aspen Plus simulation and Python calculate the net present value and payback time of the MRU for different price scenarios. The CO2 content in biogas and landfill gas limit the CO/H2 ratio to 1.3 and 0.9, respectively, which increases the olefins content of the final product. Compressors are the main source of capital cost while the labor cost represents 20–25% of the variable cost. An analysis of the impact of the plant dimension demonstrated that the higher number represents a favorable business model for this unit. A minimal production of 7,300,000 kg y−1 is required for MRU to have a positive net present value after 10 years when natural gas is the feedstock.

Dynamic Programming Approach for Online Freeway Flow Propagation Adjustment

2002 ◽  
Vol 1802 (1) ◽  
pp. 263-270 ◽  
Author(s):  
Xuesong Zhou ◽  
Hani S. Mahmassani
Keyword(s):  
Dynamic Programming ◽  
Control Method ◽  
Dynamic Programming Algorithm ◽  
Superior Performance ◽  
Programming Algorithm ◽  
Programming Approach ◽  
Base Case ◽  
Solution Quality ◽  
Flow Propagation ◽  
The Impact

An optimization framework for online flow propagation adjustment in a freeway context was proposed. Instead of performing local adjustment for individual links separately, the proposed framework considers the interconnectivity of links in a traffic network. In particular, dynamic behavior in the mesoscopic simulation is approximated by the finite-difference method at a macroscopic level. The proposed model seeks to minimize the deviation between simulated density and anticipated density. By taking advantage of the serial structure of a freeway, an efficient dynamic programming algorithm has been developed and tested. The experiment results compared with analytic results as the base case showed the superior performance of dynamic programming methods over the classical proportion control method. The effect of varying update intervals was also examined. The simulation results suggest that a greedy method considering the impact of inconsistency propagation achieves the best trade-off in terms of computation effort and solution quality.

scholarly journals An Analysis of the Effectiveness of Two Rainwater Harvesting Systems Located in Central Eastern Europe

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 458 ◽  
Author(s):  
Agnieszka Stec ◽  
Martina Zeleňáková
Keyword(s):  
Sensitivity Analysis ◽  
Net Present Value ◽  
Rainwater Harvesting ◽  
Payback Period ◽  
Practical Aspect ◽  
Financial Ratios ◽  
Present Value ◽  
Toilet Flushing ◽  
Harvesting Systems ◽  
The Impact

Decentralized water systems are perceived as solutions that not only save water, but also as a way to partially or completely become independent from centralized suppliers. Taking this into account, an analysis of the effectiveness of rainwater harvesting systems (RWHS) for toilet flushing in existing academic facilities located in Poland and in Slovakia was carried out. The tests took into account the different volumes of storage tanks collecting rainwater. On the basis of two financial ratios, namely Net Present Value and Discounted Payback Period, the profitability of these systems was also assessed. The research was extended by the sensitivity analysis, which allowed determination of the impact of changes in individual cost components on the financial effectiveness of the investments considered. The results obtained clearly showed that the implementation of RWHS in the dormitory in Rzeszów was unprofitable for all tank capacities tested, and the payback period significantly exceeded the period of 30 years accepted for the analysis. Completely different results were obtained for RWHS in a dormitory located in the city of Košice, for which the financial ratios NPV (Net Present Value) and DPP (Discounted Payback Period) were very favorable. It was also confirmed by the results of the sensitivity analysis. The use of rainwater for toilet flushing caused that it was possible to achieve water savings of an average of 29% and 18%, respectively, for facilities located in Slovakia and Poland. The results of the research have a practical aspect and can provide an indication for potential investors and managers of academic facilities, similar to those analyzed in the article. Taking into account that in many countries water and sewage rates are significantly higher than in Poland and Slovakia, the cost-effectiveness of using the analyzed installation options in these countries could be even higher.

scholarly journals Assessment of Broad-Leaved Forest Stand Management

2019 ◽  
Vol 40 (2) ◽  
pp. 365-375 ◽  
Author(s):  
Yasushi Suzuki ◽  
Tetsuhiko Yoshimura
Keyword(s):  
Interest Rates ◽  
Net Present Value ◽  
Road Construction ◽  
Japanese Cedar ◽  
Charcoal Production ◽  
Fast Growing ◽  
Stand Management ◽  
Growing Stock ◽  
Large Trees ◽  
Quercus Glauca

There are many broad-leaved forests in Japan that were formerly managed for charcoal production, which have been abandoned for decades. Appropriate thinning can revitalize these forests if the cost balance of the management is positive. Two critical elements are the construction of spur roads to facilitate mechanized harvesting operations and management planning that considers stand properties such as the growing stock, species, and tree size distribution. We surveyed three abandoned former broad-leaved coppice stands; one coastal, one cool temperate and one warm temperate. The stock in all three stands exceeded 300 m3 ha-1, two- to three-fold the official forest registry data estimates. The dominant species in terms of tree numbers are Castanopsis sieboldii, Pieris japonica, and Quercus glauca. Medium-sized trees involve those well suited for firewood, i.e., Quercus acuta, Quercus glauca, Quercus serrata, etc. Each plot contained a few large trees that potentially have a high market value, e.g., Cinnamomum camphora, Zelkova serrata, Abies firma, etc. The average income from harvested trees was estimated to be 10200 JPY (Japanese Yen) m-3, whereas the thinning costs would be 3200 to 5400 JPY m-3, with the additional spur road construction costs. The management cost balance of a broad-leaved stand in a 60 year rotation was evaluated with both Net Present Value (NPV) (for interest rates of 1, 2, 3, and 4%) and Internal Rate of Return (IRR). This balance was compared with that of a typical plantation stand of Japanese cedar (Cryptomeria japonica) and of a fast-growing plantation stand of Chinese fir (Cunninghamia lanceolata). The estimated NPVs were largest for the fast-growing plantation stand, second largest for the typical plantation stand, and lowest for the broad-leaved stand with a NPV interest rate of 1 + %. However, the IRR of the broad-leaved stand was the highest, followed by that of the fast-growing plantation stand, while the IRR of the typical plantation stand was the lowest. This order was the same for NPVs assuming higher interest rates. 1 JPY=0.0086 € on April 29, 2019.

scholarly journals Assessment of the Nutritional Impact of Agricultural Research: The Case of Mungbean in Pakistan

2005 ◽  
Vol 26 (3) ◽  
pp. 287-294 ◽  
Author(s):  
Katinka Weinberger
Keyword(s):  
Net Present Value ◽  
Agricultural Research ◽  
Low Cost ◽  
Secondary Data ◽  
Marginal Effect ◽  
Micronutrient Deficiencies ◽  
Iron Intake ◽  
Present Value ◽  
Piece Rate ◽  
The Impact

Background Evaluation of agricultural research often neglects consumption and nutrition aspects. Yet agricultural research can address micronutrient malnutrition by improving both quantity and quality of food intake. Objective To briefly review the conceptual linkages between agriculture and nutrition, to estimate the strength of the relationship between iron intake and productivity outcomes, and to estimate the nutritional benefit of improved mungbean varieties in terms of net present value. This paper presents a methodology for assessing the nutritional impact of mungbean, and summarizes current impact evidence on the path from mungbean research to consumption. Methods A consumption study was conducted among female piece-rate workers in Pakistan to analyze the impact of iron consumption on productivity, measured in wages. A two-stage least-squares analysis was used to estimate the elasticity of iron intake on wages. The results derived from this study were extrapolated to country level using secondary data sources. Results We found that anemia among women was widespread. Approximately two-thirds of women suffered from mild or severe anemia (Hb < 12 g/dL). We found the elasticity of bioavailable iron on productivity measured in wages was 0.056, and the marginal effect was 9.17 Pakistani rupees per additional mg of bioavailable iron consumed. Using the model results we estimated the impact of mungbean research on nutrition, in terms of productivity effects, and found it was substantial, ranging from US$7.6 to 10.1 million cumulative present value (in 1995 US$ at 5% discount rate). Conclusions Agriculture certainly plays an important role in the reduction of malnutrition. Agricultural research has greatly contributed to the reduction of hunger and starvation by providing millions of hungry people with access to low-cost staple foods. Now, as the challenge shifts to the reduction of micronutrient deficiencies, more efforts must be directed toward crops high in micronutrients, such as pulses and vegetables.

SYLVER: Modelling the Impact of Silviculture on Yield, Lumber Value, and Economic Return

1988 ◽  
Vol 64 (2) ◽  
pp. 127-131 ◽  
Author(s):  
Kenneth J. Mitchell
Keyword(s):  
Net Present Value ◽  
Financial Analysis ◽  
Wood Properties ◽  
Growth And Yield ◽  
Present Value ◽  
Silvicultural Treatments ◽  
Intensive Forest Management ◽  
Product Value ◽  
Analysis System ◽  
The Impact

Intensive forest management requires an understanding of the effect that silvicultural treatments have on wood properties, standing yield, log quality, product value, and net present value. These needs are addressed by a system of models (SYLVER) which includes the Tree and Stand Simulator (TASS), Root Rot Simulator (ROTSIM), Sawmill Simulator (SAWSIM), and the new Financial Analysis System (FAN$Y). The latter will be used by field foresters to compare the merits of candidate treatments for specific stands. Key words: Silviculture, growth and yield, juvenile wood, log quality, end-product value, net present value, Pseudotsuga menziesii, Phellinus weirii, modelling, TASS, ROTSIM, SAWSIM, FAN$Y, SYLVER.

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