| 1. |
- Hejazian, Mohammad, et al.
(author)
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Estimating the economic life of forest machinery using the cumulative cost model and cost minimization model in Iranian Caspian forests
- 2018
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In: Journal of Forest Science. - 1212-4834 .- 1805-935X. ; 64:5, s. 216-223
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Journal article (peer-reviewed)abstract
- This study was conducted in order to estimate the economic life of two models of rubber-tired skidders, namelyTimberjack 450C and HSM 904, in Iranian Caspian forests. The total annual costs and average cumulative cost ofskidders were calculated by life-cycle costing analysis. The economic life of the machines was estimated by boththe cumulative cost model and cost minimization model. The results indicated that the economic life of Timberjack450C and HSM 904 is 7,700 h (at the end of the 11th year) and 15,300 h (at the end of the 17th year), respectively,using the cost minimization model. Furthermore, the results indicated that the economic life of Timberjack 450Cand HSM 904 is 9,100 h (at the end of the 13th year) and 11,900 h (at the end of the 21st year), respectively, usingthe cumulative cost model. The cumulative cost model estimated the economic life of skidders longer than the costminimization model.
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| 2. |
- Hejazian, Mohammad, et al.
(author)
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Wood transportation machine replacement using goal programming
- 2019
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In: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; , s. 1-8
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Journal article (peer-reviewed)abstract
- Farm tractor + trailers play a key role in wood transportation after forests are logged. Despite of the fact that a forwarder is a forestry vehicle that carries felled logs for shorter distances off the ground, tractors are still used in some forest areas of the world, such as the Hyrcanian forest in northern Iran. This study was conducted to investigate the possibility of using both the light forwarder and forestry trailer instead of a farm tractor + trailer in wood transportation. The optimal machine option for wood transportation is determined using goal programming model in the study area. In this paper, multi-objective goals (such as economic, operational, environmental and ergonomic) were considered. The results showed that considering only the economic goal, the contractor could save up to 44% in costs by purchasing and replacing a forestry trailer with a 2-wheel trailer attached to the farm tractor. In addition, considering various goals, a light forwarder could be selected as the optimal machine. Currently, the most important objectives of all forest contractors are to establish economic goals and reduce wood transportation costs. Since other goals, such as environmental and ergonomic, are also important; it is suggested that multi-objective approaches should use for planning.
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| 3. |
- Wells, Daniel J., et al.
(author)
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Observations of phase changes in monoolein during high viscous injection
- 2022
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In: Journal of Synchrotron Radiation. - : International Union Of Crystallography. - 0909-0495 .- 1600-5775. ; 29:3, s. 602-614
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Journal article (peer-reviewed)abstract
- Serial crystallography of membrane proteins often employs high-viscosity injectors (HVIs) to deliver micrometre-sized crystals to the X-ray beam. Typically, the carrier medium is a lipidic cubic phase (LCP) media, which can also be used to nucleate and grow the crystals. However, despite the fact that the LCP is widely used with HVIs, the potential impact of the injection process on the LCP structure has not been reported and hence is not yet well understood. The self-assembled structure of the LCP can be affected by pressure, dehydration and temperature changes, all of which occur during continuous flow injection. These changes to the LCP structure may in turn impact the results of X-ray diffraction measurements from membrane protein crystals. To investigate the influence of HVIs on the structure of the LCP we conducted a study of the phase changes in monoolein/water and monoolein/buffer mixtures during continuous flow injection, at both atmospheric pressure and under vacuum. The reservoir pressure in the HVI was tracked to determine if there is any correlation with the phase behaviour of the LCP. The results indicated that, even though the reservoir pressure underwent (at times) significant variation, this did not appear to correlate with observed phase changes in the sample stream or correspond to shifts in the LCP lattice parameter. During vacuum injection, there was a three-way coexistence of the gyroid cubic phase, diamond cubic phase and lamellar phase. During injection at atmospheric pressure, the coexistence of a cubic phase and lamellar phase in the monoolein/water mixtures was also observed. The degree to which the lamellar phase is formed was found to be strongly dependent on the co-flowing gas conditions used to stabilize the LCP stream. A combination of laboratory-based optical polarization microscopy and simulation studies was used to investigate these observations.
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