A Study on Methods of Capacity Research for Performance Evaluation

Hyoungjun Kim,Ullrich Martin,Fabian Hantsch 한국도시철도학회 2017 IJAR Vol.5 No.2

The objective of railway capacity research is to determine the dimension of infrastructure, operating performance and quality of operation. If two component parts are known, the third one can be acquired. In this paper, two different capacity research methods are presented and described. The first is the Hertel’s adapted method based on queueing theory, which is used to calculate railway capacity analyzed by the waiting time function and the recommended area of traffic flow. Another one is the Yamagishi method, which is the most widely utilized method to calculate railway capacity in South Korea. This paper compares the maximum capacity of these two methods for trains running on the identical infrastructure. In the conclusion, a description of the method’s strengths and limitations is presented and the differences of the two methods are represented. Furthermore the future research works to better correlate the models and reality is discussed

Calibration of Timetable Parameters for Rail-Guided Systems

Weiting Zhao,Ullrich Martin,Yong Cui,Maureen Kosters 한국철도학회 2016 International Journal of Railway Vol.9 No.1

In order to achieve a comprehensive utilization of railway networks, it is necessary to accurately assess the timetable indicators that effect the train operation. This paper describes the parameter calibration for two timetable indicators: scheduled running time and scheduled dwell time. For the scheduled running time, an existing model is employed and the single timetable parameter (percentage of minimum running time) in that model is optimized. For the scheduled dwell time, two intrinsic characteristics: the significance of stations and the average headway at each station are proposed firstly to form a new model, and the corresponding timetable parameters (the weight of the significance and the weight of the average headway) are calibrated subsequently. The Floyd Algorithm is used to obtain the connectivity among stations, which represents the significance of the stations. A case study is conducted in a light rail transportation system with 17 underground stations. The results of this research show that the optimal value of the scheduled running time parameter can be automatically determined, and the proposed model for the scheduled dwell time works well with a high coefficient of determination and low relative root mean square error through the leave-one-out validation.

Calibration of Timetable Parameters for Rail-Guided Systems

Zhao, Weiting,Martin, Ullrich,Cui, Yong,Kosters, Maureen The Korean Society for Railway 2016 International Journal of Railway Vol.9 No.1

In order to achieve a comprehensive utilization of railway networks, it is necessary to accurately assess the timetable indicators that effect the train operation. This paper describes the parameter calibration for two timetable indicators: scheduled running time and scheduled dwell time. For the scheduled running time, an existing model is employed and the single timetable parameter (percentage of minimum running time) in that model is optimized. For the scheduled dwell time, two intrinsic characteristics: the significance of stations and the average headway at each station are proposed firstly to form a new model, and the corresponding timetable parameters (the weight of the significance and the weight of the average headway) are calibrated subsequently. The Floyd Algorithm is used to obtain the connectivity among stations, which represents the significance of the stations. A case study is conducted in a light rail transportation system with 17 underground stations. The results of this research show that the optimal value of the scheduled running time parameter can be automatically determined, and the proposed model for the scheduled dwell time works well with a high coefficient of determination and low relative root mean square error through the leave-one-out validation.

The ascomycete Xylaria polymorpha produces an acetyl esterase that solubilises beech wood material to release water-soluble lignin fragments

Nghi, Do Huu,Ullrich, Rene,Moritz, Franco,Huong, Le Mai,Giap, Vu Dinh,Chi, Do Huu,Hofrichter, Martin,Liers, Christiane 한국응용생명화학회 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.3

Three ascomycetous soft-rot fungi belonging to the family Xylariaceae were found to produce high levels of a p-nitrophenyl acetate-hydrolyzing activity during growth on lignocellulosic materials, i.e., wheat straw and beech wood chips. Accordingly, Kretzschmaria deusta, Morchella elata, Xylaria polymorpha were seemingly most noteworthy acetyl esterase producers and, of which, X. polymorpha (strain A35) was chosen for further studies. Induction study indicated that raw carbohydrate sources, such as beech wood, rape straw, birch wood, and wheat straw, were extremely important for acetyl esterase production. Acetyl esterase of X. polymorpha was produced in solid-state culture on wheat straw and purified by different steps of anion-exchange and size-exclusion chromatography. This purified enzyme ($M_W=44kDa$ and pI values of 3.5-3.6) exhibited the capability to solubilise in vitro beech wood to release water-soluble lignin fragments with molecular masses of 1-3 kDa as analyzed by high performance size exclusion chromatography.

Bioconversion of Lignocellulosic Materials with the Contribution of a Multifunctional GH78 Glycoside Hydrolase from Xylaria polymorpha to Release Aromatic Fragments and Carbohydrates

( Christiane Liers ),( Rene Ullrich ),( Harald Kellner ),( Do Huu Chi ),( Dang Thu Quynh ),( Nguyen Dinh Luyen ),( Le Mai Huong ),( Martin Hofrichter ),( Do Huu Nghi ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.10

A bifunctional glycoside hydrolase GH78 from the ascomycete Xylaria polymorpha (XpoGH78) possesses catalytic versatility towards both glycosides and esters, which may be advantageous for the efficient degradation of the plant cell-wall complex that contains both diverse sugar residues and esterified structures. The contribution of XpoGH78 to the conversion of lignocellulosic materials without any chemical pretreatment to release the water-soluble aromatic fragments, carbohydrates, and methanol was studied. The disintegrating effect of enzymatic lignocellulose treatment can be significantly improved by using different kinds of hydrolases and phenoloxidases. The considerable changes in low (3 kDa), medium (30 kDa), and high (> 200 kDa) aromatic fragments were observed after the treatment with XpoGH78 alone or with this potent cocktail. Synergistic conversion of rape straw also resulted in a release of 17.3 mg of total carbohydrates (e.g., arabinose, galactose, glucose, mannose, xylose) per gram of substrate after incubating for 72 h. Moreover, the treatment of rape straw with XpoGH78 led to a marginal methanol release of approximately 17 μg/g and improved to 270 μg/g by cooperation with the above accessory enzymes. In the case of beech wood conversion, the combined catalysis by XpoGH78 and laccase caused an effect comparable with that of fungal strain X. polymorpha in woody cultures concerning the liberation of aromatic lignocellulose fragments.

The ascomycete Xylaria polymorpha produces an acetyl esterase that solubilises beech wood material to release water-soluble lignin fragments

Do Huu Nghi,Rene´ Ullrich,Franco Moritz,Le Mai Huong,Vu Dinh Giap,Do Huu Chi,Martin Hofrichter,Christiane Liers 한국응용생명화학회 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.3

Three ascomycetous soft-rot fungi belonging to the family Xylariaceae were found to produce high levels of a p-nitrophenyl acetate-hydrolyzing activity during growth on lignocellulosic materials, i.e., wheat straw and beech wood chips. Accordingly, Kretzschmaria deusta, Morchella elata, Xylaria polymorpha were seemingly most noteworthy acetyl esterase producers and, of which, X. polymorpha (strain A35) was chosen for further studies. Induction study indicated that raw carbohydrate sources, such as beech wood, rape straw, birch wood, and wheat straw, were extremely important for acetyl esterase production. Acetyl esterase of X. polymorpha was produced in solid-state culture on wheat straw and purified by different steps of anion-exchange and size-exclusion chromatography. This purified enzyme (MW = 44 kDa and pI values of 3.5–3.6) exhibited the capability to solubilise in vitro beech wood to release water-soluble lignin fragments with molecular masses of 1–3 kDa as analyzed by high performance size exclusion chromatography.