Warehouse capacity sharing via transshipment for an integrated two-echelon supply chain

Feng, X.,Moon, I.,Ryu, K. Elsevier Science Ltd ; Pergamon ; Elsevier Science 2017 TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANS Vol.104 No.-

<P>Warehouse capacity constraint has been one obstacle to achieving the channel-wide optimal decision in inventory management. We studied an integrated inventory model consisting of a single vendor and multiple buyers with warehouse capacity sharing via transshipment. We proposed an optimal transshipment policy by developing nonlinear programming models and genetic algorithms as well as obtaining Karush-Kuhn-Tucker points. This inventory policy can significantly reduce the channel-wide cost and the performance is influenced by the consideration of fixed transshipment costs. Sensitivity analyses show that parameters have different impacts on the channel-wide cost and the performances of the algorithms. (C) 2017 Published by Elsevier Ltd.</P>

Passenger facility charge vs. airport improvement program funds: A dynamic network DEA analysis for U.S. airport financing

Chang, Y.T.,Park, H.,Zou, B.,Kafle, N. Elsevier Science Ltd ; Pergamon ; Elsevier Science 2016 TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANS Vol.88 No.-

<P>Passenger Facility Charge (PFC) and the Airport Improvement Program (AIP) are two major sources to finance U.S. airports. This paper develops a novel dynamic network DEA framework to investigate the substitutability between PFC and AIP funds. We find that the studied U.S. airports can substitute PFC for 8-35% of the current AIP funds and contribute significantly to the proposed plan of the US congress to cut AIP funding. In addition, the amount of PFC-for-AIP funds substitution negatively correlates with the productive efficiency of airports. The findings send an important message for future policy reforms on U.S. airport financing. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Supply chain coordination with a single supplier and multiple retailers considering customer arrival times and route selection

Moon, I.,Feng, X. Elsevier Science Ltd ; Pergamon ; Elsevier Science 2017 TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANS Vol.106 No.-

<P>We address a novel decentralized supply chain with one supplier and multiple independent retailers based on the practice of several supply chains in the real world. Coordination of such a supply chain has rarely been studied. Despite overcoming the well-known double marginalization, the supplier's route selection can obstruct supply chain coordination. We present a wholesale-price-and-carpooling contract to coordinate such a supply chain. We demonstrate supply chain coordination under such a contract and show that the profit along the supply chain can be arbitrarily allocated. We show that the popular revenue-sharing contract may lose flexibility in profit allocations. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Biomethanation potential of marine macroalgal Ulva biomass in sequencing batch mode: Changes in process performance and microbial community structure over five cycles

Jung, H.,Kim, J.,Lee, J.,Hwang, S.,Lee, C. Pergamon ; Elsevier Science Ltd 2016 Biomass & bioenergy Vol.91 No.-

<P>Anaerobic digestion (AD) of Ulva biomass, a promising next-generation feedstock for energy production, was investigated in sequencing batch mode. Over five cycles of operation, the methane yield decreased more than twofold (from 0.15 to 0.07 L/g CODfed), while the organic treatment efficiency (i.e., chemical oxygen demand (COD) removal) remained fairly constant (53.7-61.1%). Such changes in reactor performance were related with structural variations in the microbial community, particularly the bacterial community, with repeated cycles. Methanosaeta- and Methanolinea-related populations were most likely the main aceticlastic and hydrogenotrophic methanogens, respectively, in the reactor. The emergence and prevalence of sulfate-reducing bacteria (SRBs), primarily a Solitalea-related population, most likely resulted in increased consumption of organic substrates for sulfate reduction, rather than methane production, in later cycles. Our observations suggest that the metabolic properties of the reactor changed with the transition of the bacterial community structure over cycles, and the metabolic shift had a negative effect on methanogenesis. The sequencing batch operation strategy applied in this study was not suitable for maximizing methane production from Ulva biomass, although the treatment efficiency was fairly stable. Robust control of SRB activity is necessary for more stable and efficient biomethanation of Ulva biomass in sequencing batch mode. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Comparing the influence of acetate and chloride anions on the structure of ionic liquid pretreated lignocellulosic biomass

Kim, H.,Ahn, Y.,Kwak, S.Y. Pergamon ; Elsevier Science Ltd 2016 Biomass & bioenergy Vol.93 No.-

<P>The effect of the anion type, in an ionic liquid, on the transition of the crystalline structure when lignocellulose was pretreated in 1-ethyl-3-methylimidazolium acetate (EmimOAC) or 1-ethyl-3-methylimidazolium chloride (EmimCl) was studied. The influence of the pretreatment on the composition, the molecular structure, and the crystalline structure was observed using Fourier-transform infrared (FT-IR) compositional analysis, thermogravimetric analysis (TGA), rheological behavior, and Xray diffraction (XRD). Compared to EmimCl, EmimOAC pretreatment substantially decreased the lignin and hemicellulose contents. The pretreatment also significantly changed the entanglement or cross-linking state of polymer chains in the lignocellulose solution. The changes in lignin content and the transformation from cellulose I to II were dependent on the anion type of the ionic liquid. The pretreated samples were recrystallized to cellulose II only in EmimOAC, whereas the samples pretreated with EmimCl had both cellulose I and II structures present at the same time. (C) 2016 Published by Elsevier Ltd.</P>

Study of rain attenuation in Ka band for satellite communication in South Korea

Shrestha, S.,Choi, D.Y. Elsevier Science Ltd ; Pergamon 2016 Journal of Atmospheric and Solar-Terrestrial Physi Vol.148 No.-

<P>The important factor to be considered in the link budget estimation for satellite communication systems, operating at frequencies above 10 GHz is the rain attenuation. Scattering and absorption are the main concern for system designers at these frequency bands. This has resulted in the need for suitable prediction models that can best provide estimates of attenuation due to rain with available information of rain attenuation data. Researchers have developed models that can be used to estimate 1-min rainfall attenuation distribution for earth space link but there is still some confusion with regard to choosing the right model to predict attenuation for the location of interest. In this context, the existing prediction models need to be tested against the measured results. This paper presents studies on rain attenuation at 19.8 GHz, which specifies the performance parameters for Ka-Band under earth space communication system. It presents the experimental result of rain rates and rain-induced attenuation in 19.8 and 20.73 GHz for vertical and circular polarization respectively. The received signal data for rain attenuation and rain rate were collected at 10 s intervals over a three year periods from 2013 to 2015. The data highlights the impact of clear air variation and rain fade loss. Rain rate data was measured through OTT Parsivel. During the observation period, rain rates of about 50 mm/h and attenuation values of 11.6 dB for 0.01% of the time were noted. The experimental link was set up at Korea Radio Promotion Association, Mokdong, Seoul. Out of several models, this paper present discussion and comparison of ITU-R P.618-12, Unified Method, Dissanayake Allnutt and Haidara (DAH), Simple Attenuation (SAM), Crane Global and Ramachandran and Kumar models. The relative error margin of 27.51, 89.84,72.46% and 67.24, 130.84, 166.48% are obtained for 0.1%, 0.01% and 0.001% of the time for 19.8 and 20.73 GHz under vertical and circular polarization respectively from ITU-R P. 618-12 method which has been analyzed in the further section of this article. In order to obtain the better approximation of rain induced attenuation, the suitable method is proposed for earth space link whose efficiency have been compared with prominent rain attenuation models. The method provides useful information for system engineers and researchers in making a decision over the choice of suitable rain attenuation prediction method for earth space communication operating in the South Korea region. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Impacts of air-sea exchange coefficients on snowfall events over the Korean Peninsula

Kang, J.Y.,Kwon, Y.C. Elsevier Science Ltd ; Pergamon 2016 Journal of Atmospheric and Solar-Terrestrial Physi Vol.146 No.-

<P>Snowfall over the Korean Peninsula is mainly associated with air mass transformation by the fluxes across the air-sea interface during cold-air outbreaks over the warm Yellow Sea. The heat and momentum exchange coefficients in the surface flux parameterization are key parameters of flux calculations across the air-sea interface. This study investigates the effects of the air-sea exchange coefficients on the simulations of snowfall events over the Korean Peninsula using the Weather Research and Forecasting (WRF) model. Two snowfall cases are selected for this study. One is a heavy snowfall event that took place on January 4, 2010, and the other is a light snowfall event that occurred on December 2324, 2011. Several sensitivity tests are carried out with increased and decreased heat and momentum exchange coefficients. The domain-averaged precipitation is increased (decreased) with increased (decreased) heat exchange coefficient because the increased (decreased) surface heat flux leads to more (less) moist conditions in the low level of the atmosphere. On the other hand, the domain-averaged precipitation is decreased (increased) with increased (decreased) momentum exchange coefficient because the increased (decreased) momentum coefficient causes reduction (increase) of wind speed and heat flux. The variation of precipitation in the heat exchange coefficient experiments is much larger than that in the momentum exchange coefficient experiments because the change of heat flux has a more direct impact on moisture flux and snowfall amount, while the change of momentum flux has a rather indirect impact via wind speed changes. The low-pressure system is intensified and moves toward North when the heat exchange coefficient is increased because warming and moistening of the lower atmosphere contributes to destabilize the air mass, resulting in the change of precipitation pattern over the Korean Peninsula in the heat exchange coefficient experiments. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Combustion behavior of low-rank coal impregnated with glycerol

Lee, B.H.,Sh, L.,Bae, J.S.,Choi, Y.C.,Jeon, C.H. Pergamon ; Elsevier Science Ltd 2016 Biomass & bioenergy Vol.87 No.-

<P>The addition of biomass to an existing coal-fired boiler has emerged as a prospective option for reducing CO2 emissions to mitigate the problems associated with excess global warming. However, the cost associated with retrofitting an injection system and the unstable combustion hinder the use of this option. Therefore, we propose the use of coal impregnated with glycerol as fuel that can be directly injected into an existing boiler. This is a two-in-one fuel that combines a low-rank coal (LRC) with bio-liquid matter extracted from biomass such as molasses or sugarcane juice. In this study, for the first time, we used glycerol, which is a low value co-product of biodiesel production, as the bio-liquid, because the use of molasses or sugar-cane juice raises food ethical issues. The aim of this study was to investigate the combustion behavior of coal impregnated with glycerol, using experimental and numerical methods. The results showed that the calorific value of coal impregnated with glycerol increased, and the combustibility at low and high temperatures was improved by impregnation of low-rank coal with up to 20% glycerol. We also confirmed that the combustion performance of coal impregnated with glycerol was unaffected and was identical to that of original coal. However, excess glycerol (more than 20%) led to oxygen deficiency near the burner and thermal expansion, which reduced the combustibility. The results of this study therefore suggest that less than 20% glycerol is the optimal condition for low-rank coal impregnated with glycerol. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Spatiotemporal analysis of snow cover variations at Mt. Kilimanjaro using multi-temporal Landsat images during 27 years

Park, S.H.,Lee, M.J.,Jung, H.S. Elsevier Science Ltd ; Pergamon 2016 Journal of Atmospheric and Solar-Terrestrial Physi Vol.143 No.-

<P>The Landsat TM and ETM+ images have been acquired for the long period from the 1980s until the present with the temporal resolution of a 16-day repeat cycle from the visible, near infrared (NIR), short wave infrared (SWIR) and thermal infrared (TIR) bands. The Landsat multi-temporal images have been successfully used to monitor variations of the Earth surface during 27 years. In this paper, we observe the variations of (1) the snow cover area, (2) the snowline height and (3) the land surface temperature (LST) lapse rate at Mt. Kilimanjaro using a total number of 15 Landsat-5 TM and Landsat-7 ETM+ images from June 1984 July 2011. Segmentation of normalized difference snow index (NDSI) images with a threshold of 0.6 is used to extract snow cover. Snowline altitude is then determined by combining the snow cover classification maps with a digital elevation model (DEM). And the LST lapse rate is also calculated from the TIR band in the forest area. The results from this study show that (1) the snow cover area largely decreases from 10.1 km(2) to 2.3 km(2) during about 27 years, which corresponds to a 77.2% reduction, (2) the snowline height rose from 4760 m to 5020 m by about 260 m, and (3) the LST lapse rate shifted from -5.2 degrees C/km to 2.7 degrees C/km. This study demonstrates that multi-temporal Landsat images can be successfully used for the spatiotemporal analysis of long-term snow cover changes. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Mathematical properties and constraints representation for bottom-up approaches to the evaluation of GHG mitigation policies

Kim, H.,Paik, C.,Chung, Y.,Kim, Y.J. Pergamon ; Elsevier Science Ltd 2014 TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIR Vol.32 No.-

<P>Bottom-up models, including MARKAL, MESSAGE and AIM, are widely used when analyzing the effect of greenhouse gas (GHG) abatement policies. These bottom-up models are mostly formulated as a linear programming (LP) optimization model to find both the minimal cost combination of abatement technologies and energy flows while satisfying demands. It is not unusual that the bottom-up modeling involves a great number of technical, industrial, socioeconomic and environmental constraints. Investigating representative constraints needed for analyzing GHG abatement policies, this study proposes how to implement these constraints in bottom-up modeling. (C) 2014 Elsevier Ltd. All rights reserved.</P>