Discrete-Event Simulation of Ground-Based Timber Harvesting Operations

She, Ji; Chung, Woodam; Kim, David

doi:10.3390/f9110683

Cited by 20 publications

(22 citation statements)

References 28 publications

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“…Time-and-motion studies have been widely used to evaluate the performance of individual logging equipment as well as entire harvesting systems [11,12]. This type of study has been essential for predicting machine productivity and utilization rates in various scenarios under similar working conditions [13,14]. However, this approach is limited in terms of data availability due to the relatively short period of data collection and high costs of field work [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…This type of study has been essential for predicting machine productivity and utilization rates in various scenarios under similar working conditions [13,14]. However, this approach is limited in terms of data availability due to the relatively short period of data collection and high costs of field work [14][15][16]. Additionally, a number of past studies have assessed performance using the follow-up method, which utilizes historic output records, such as productivity and costs.…”

Section: Introductionmentioning

confidence: 99%

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Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea

Lee

Han

2019

Forests

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In South Korea, logs for low-value products, such as pulpwood and fuelwood, are primarily extracted from harvest sites and transported to roadside or landing areas using small shovels. Previous studies on log extraction, however, have focused on cable yarding operations with the goal of improving productivity on steep slopes and inaccessible sites, leaving small-shovel operations relatively unexamined. Therefore, the main objectives were to determine small-shovel extraction productivity and costs and to evaluate the impact of related variables on productivity. In addition, we developed a model to estimate productivity under various site conditions. The study took place in 30 case study areas; each area has trees with stems at a diameter at breast height ranging from 18 to 32 cm and a steep slope (greater than 15%). The areas ranged from 241 to 1129 trees per hectare, with conifer, deciduous, and mixed stands. Small-shovel drives ranged from 36 to 72 m per extraction cycle from stump to landing. The results indicated that the mean extraction productivity of small-shovel operations ranged between 2.44 to 9.85 m 3 per scheduled machine hour (including all delays). At the forest level, the estimated average stump-to-forest road log production costs were US $4.37 to 17.66/m 3 . Small-shovel productivity was significantly correlated with stem size (diameter at breast height and tree volume) and total travelled distance (TTD). However, a Pearson's correlation analysis indicated that stand density and slope did not have a significant effect on productivity. Our findings provide insights into how stem size and TTD influence small shovel performance and the predictive ability of productivity. Further, this information may be a valuable asset to forest planners and managers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea

Lee

Han

2019

Forests

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“…The aim in Articles III and IV was to apply a DES model which imitates reality and behaves close to reality, similarly to Windisch et al (2015). A comparison between time study and the DES approach by She et al (2018) revealed only minor differences for machine cycle times and productivity, but found that machine utilisation rates were somewhat different. However, the authors favoured DES when analysing complex systems with machine process interactions (She et al 2018).…”

Section: Discussionmentioning

confidence: 99%

“…A comparison between time study and the DES approach by She et al (2018) revealed only minor differences for machine cycle times and productivity, but found that machine utilisation rates were somewhat different. However, the authors favoured DES when analysing complex systems with machine process interactions (She et al 2018). Furthermore, the DES method allowed effect of selected changes on the supply condition of forest chips to the end-using facility to be investigated without having the need for actual practical implementation of a terminal or innovative machinery on a larger scale, which would be risk and investment intensive, as well as time consuming.…”

Section: Discussionmentioning

confidence: 99%

Improving performance and energy efficiency of biomass supply through machine alteration and organisational redesign

Prinz¹

2019

Diss. For.

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This thesis summarises the findings of four case studies focussing on the redesign of specific aspects of the forest chip supply chain, the use of alternative terminals for chip supply, the interdependencies of chipper and chip trucks and the performance of individual machines after machine alteration. The aim of the work was to analyse and improve the fuel economy and energy efficiency of the forest chip supply system by modifying the settings of CTL harvesters, investigating the performance of an innovative hybrid chipper, introducing alternative supply systems through the use of a feed-in terminal and an analysis of forest chip supply systems under selected operational and environmental conditions. The analysis of the case studies involved individual machines and the entire forest chip supply system. Two study methods were used: work study and discrete event simulation (DES). Work study carried out to investigate the performance of individual machines and their alteration; the DES method was used for investigating the organisational redesign of the forest fuel supply system. The study resulted in the following findings and conclusions: 1) extreme machine settings have a statistically significant impact on the fuel economy of CTL harvesting machines; 2) hybrid machine technology can improve the fuel consumption and energy efficiency of chipping operations in forest chip production; nevertheless the productivity of the analysed prototype was below that for compared traditional chippers; 3) as an alternative to the direct supply of forest chips, the effect of utilising terminal operations on the overall supply cost can be quantified; terminal use improves the annual use of the supply fleet and enhances fuel supply security to the plant thereby reducing the need for supplementary fuel and 4) applying different types of types of chipper and truck-trailer combinations, supply costs and efficiencies can be quantified and vehicles with increased carrying capacity can improve the cost competitiveness. In the study an integrated approach taking physical, technological, enterprise and industrial levels of energy efficiency into account is proposed. Thereby state-of-the-art forest technology and current biomass supply ideally can be upgraded to achieve new, improved levels of performance and energy efficiency.

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“…It is located on relatively flat terrain with a stand density of 865 trees ha −1 and a basal area of 34.6 m 2 ha −1 . The average tree diameter at breast height (dbh) is 22.4 cm, and the average tree height is 19.6 m. A ground-based clearcut has been a common salvage harvest practice in this area due to the high mortality rate [69]. After accounting for slope and skidding distance, a total of 627 harvest units in average size of 5.4 ha were identified as operationally feasible areas for salvage harvest [70].…”

Section: Problem Statementmentioning

confidence: 99%

Economic and Environmental Optimization of the Forest Supply Chain for Timber and Bioenergy Production from Beetle-Killed Forests in Northern Colorado

She

Chung

Han

2019

Forests

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Harvesting mountain pine beetle-infested forest stands in the northern Colorado Rocky Mountains provides an opportunity to utilize otherwise wasted resources, generate net revenues, and minimize greenhouse gas (GHG) emissions. Timber and bioenergy production are commonly managed separately, and their integration is seldom considered. Yet, degraded wood and logging residues can provide a feedstock for bioenergy, while the sound wood from beetle-killed stands can still be used for traditional timber products. In addition, beneficial greenhouse gas emission (GHG) savings are often realized only by compromising net revenues during salvage harvest where beetle-killed wood has a relatively low market value and high harvesting cost. In this study we compared Sequential and Integrated decision-making scenarios for managing the supply chain from beetle-killed forest salvage operations. In the Sequential scenario, timber and bioenergy production was managed sequentially in two separate processes, where salvage harvest was conducted without considering influences on or from bioenergy production. Biomass availability was assessed next as an outcome from timber production managed to produce bioenergy products. In the Integrated scenario, timber and bioenergy production were managed jointly, where collective decisions were made regarding tree salvage harvest, residue treatment, and bioenergy product selection and production. We applied a multi-objective optimization approach to integrate the economic and environmental objectives of producing timber and bioenergy, and measured results by total net revenues and total net GHG emission savings, respectively. The optimization model results show that distinctively different decisions are made in selecting the harvesting system and residue treatment under the two scenarios. When the optimization is fully economic-oriented, 49.6% more forest areas are harvested under the Integrated scenario than the Sequential scenario, generating 12.3% more net revenues and 50.5% more net GHG emission savings. Comparison of modelled Pareto fronts also indicate the Integrated decision scenario provides more efficient trade-offs between the two objectives and performs better than the Sequential scenario in both objectives.

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Discrete-Event Simulation of Ground-Based Timber Harvesting Operations

Cited by 20 publications

References 28 publications

Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea

Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea

Improving performance and energy efficiency of biomass supply through machine alteration and organisational redesign

Economic and Environmental Optimization of the Forest Supply Chain for Timber and Bioenergy Production from Beetle-Killed Forests in Northern Colorado

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