Optimization of vertical alignment using general transition curves

Andrzej Kobryń 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.7

The paper presents an original design method of vertical alignment of road routes. It involves the use of the so-called general oruniversal transition curves. These curves describe the entire curvilinear transition between two straight lines using a single equation. They also have only one curvature extremum, which is of great practical significance. By using general transition curves, it ispossible to obtain a completely curvilinear course of vertical alignment ensuring full smoothness at the connection points of eachcurve. The paper presents a methodology of creating appropriate approximation equations for longitudinal profile points as well astheir development using the method of least squares in order to determine the parameters for optimum vertical alignment. Theproposed approach reflects the principles of the so-called polynomial routing and makes it possible to create vertical alignment thatmay be composed of both general transitional curves, as well as straight line sections. Numerical studies of several longitudinalprofiles on the site have shown that the proposed approach allows for a better fit to the vertical terrain than traditional design methodsof vertical alignment, i.e. using tangent polygon of parabolic arcs.

Technical-Economical Evaluation of Chain Vertical Alignment in Underground Urban Subways: The Case of Qom Subway, Line A

Abdi Kordani, Ali,Mehrara Molan, Amirarsalan The Korean Society for Railway 2014 International Journal of Railway Vol.7 No.2

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

Technical-Economical Evaluation of Chain Vertical Alignment in Underground Urban Subways

Ali Abdi Kordani,Amirarsalan Mehrara Molan 한국철도학회 2014 International Journal of Railway Vol.7 No.2

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

Vertical Alignment of Liquid Crystal on Film of Plant-based Polysaccharide Derivatives

조연수,문지현,양다은,강효 한국고무학회 2023 엘라스토머 및 콤포지트 Vol.58 No.1

In this study, we investigate the liquid crystal (LC) alignment of LC cells created from plant-based polysaccharide derivatives, such as guar gum. Guar gum films exhibit satisfactorily high optical transparency in the visible light region (400-750 nm). For example, the transmittance of polyimide films, which are the most typically used LC alignment layers, is 87%, whereas that of guar gum films deposited onto a glass substrate at a wavelength of 550 nm is approximately 99%. The observed LC alignment depends on the rubbing depth. For example, an LC cell comprising a guar gum film fabricated via rubbing at rubbing depths of 0.1, 0.2, 0.3, and 0.4 mm exhibits a planar LC alignment, whereas it exhibits a vertical LC alignment at a rubbing depth of 0.5 mm. Additionally, the LC alignment is shown to be correlated with the total surface energy of the guar gum films. When the total surface energy of a rubbed guar gum film exceeds 58.10 mJ/m2, an LC cell comprising the guar gum film exhibits a stable and vertical LC alignment. Therefore, guar gum can be used to realize the vertical alignment system of LC via a simple adjustment of the rubbing depth.

수직배향 네마틱 액정셀에서의 주입속도에 미치는 전기장 효과

전연문,김상균,김연식,안명환,이승희,Jeon, Yeon-Mun,Kim, Sang-Gyun,Kim, Youn-Sik,An, Myeong-Hwan,Lee, Seung-Hee 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.7

Injection time of liquid crystal (LC) by capillary action in a vertically aligned (VA) nematic LC cell takes longer than that in a homogeneously aligned (HA) LC cell because Miesowicz viscosity in the former is bigger than that in the latter. To reduce liquid crystal injection time in the VA cell, we applied vertical electric field while injecting so that the orientation of LC molecules is changed from vertical alignment to homogeneous alignment. Consequently, the injection speed is improved by 25 % when compared with the cell without an applied field.

Automatic vertical alignment of liquid crystals by photo-polymerizable amphiphiles and polyhedral oligomeric silsequioxane with strong polar anchoring energy

윤원진,정광운 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

For formation of vertical alignment (VA) of liquid crystal (LC) automatically, a photo-polymerizable reactive amphiphile (Ita3C12) is designed and synthesized. Ita3C12 is consist of hydrophilic carboxylic acid, three alkyl tails, and a reactive vinyl function. Since a hydrophilic carboxylic acid was chemically attached to the end of Ita3C12, the Ita3C12 dissolved in the host nematic (N) LC medium were migrated toward the substrates and automatically determined NLC direction vertically. Furthermore, vinyl function of Ita3C12 was possible to stabilize the VA layer by the photo-polymerization with methacryl polyhedral oligomeric silsesquioxane (MAPOSS) cross-linkers. The polymerized robust VA layer exhibited a strong surface anchoring energy without generating any light scatterings. **This work was supported by the BRL 2015042417, and MOTIE/KDRC 10051334 and BK21 plus program, Korea.

Vertical Alignment of Liquid Crystals Using an In Situ Self-Assembled Layer of an Amphiphilic Block Copolymer

손인태,김재홍,이병선,김천호,유지용,현규,우종표,이준협 한국고분자학회 2016 Macromolecular Research Vol.24 No.3

We have employed an in situ self-assembled layer of an amphiphilic block copolymer to vertically align liquid crystals (LCs). The amphiphilic block copolymer used consisted of hydrophobic polyethylene (PE) and hydrophilic polyethylene glycol (PEG). The degrees of vertical alignment obtained for various PEG contents and polymer concentrations were compared through polarized optical microscopy, electro-optical measurements, and contact angle measurements. The LC cell prepared using a PEG content of 50% and concentration of 0.05 wt% exhibited the most uniform vertical alignment. Moreover, the electro-optical characteristics of this LC cell were similar to those of a conventional LC cell fabricated using a polyimide alignment layer. This was because the anchoring force for a PEG content of 50% was sufficiently high, allowing for uniform alignment. Since the proposed method involves only the simple doping of a low-concentration (0.05 wt%) amphiphilic block copolymer, it is also cost effective.

Liquid crystal alignment effects for the photo-aligned VA-LCD on the photo-polymer

Hwang, Jeoung-Yeon,Seo, Dae-Shik,Hahn, Eun-Joo,Kim, Jae-Hyung The Korean Institute of Electrical and Electronic 2000 Transactions on Electrical and Electronic Material Vol.1 No.3

In this study the new photo-alignment material copoly(PM4Ch-ChMa)(copoly (poly (4-methancryloyloxy)chalcone-cholesteryl methacry late)) was synthesized, Also, the liquid crystal (LC) aligning capabilities and the electro-optical(EO) characteristics for the photo-aligned vertical-aligned(VA)-LC display(LCD) were studied. The monodomain alignment of the NLC for the photo-aligned VA-LCD by linearly polarized UB exposure on the Photo-dimerized copoly(PM4Ch-ChMA) surface was observed,. Excellent Voltage-transmittance characteristics for the VA-LCD photo-aligned by polarized UV exposure on the copoly (PM4Ch-ChMA) surfaces for 1 min was achieved. The response time of the VA-LCD photo-aligned by polarized UV exposure on the copoly (PM4Ch-ChMA) surfaces for 1 min was 39.3 ms, We suggest that the photo-dimerized chacone group increased with increasing UV exposure time, which then contributes to a low response time of the photo-aligned VA-LCD on the copoly (PM4Ch-ChMA) surfaces.

Boron nitride/silicon carbide binary filler with vertical particle alignment system for high thermal conductive composite

김기호,김주헌 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Thermally conductive BN/SiC binary filler and epoxy composite materials were fabricated via magnetic alignment. Owing to its anisotropy, the vertically aligned BN composite had a high thermal conductivity and generated a vertical heat flow path. When the SiC nanoparticles were added to the binary filler, they hindered BN-particle aggregation and led to the formation of a three-dimensional heat conduction path. The maximum thermal conductivity (5.77 W/mK) was obtained with an addition of SiC filler, and was 3.08-fold and 1.1-fold higher than that of randomly mixed BN and vertically aligned BN composites, respectively. The additional SiC-Fe3O4 particles resulted in significant aggregation of the filler, which in turn led to a decrease in the thermal conductivity. The measured storage modulus of the BN-Fe3O4/SiC binary filler composite was also higher than those of the BN-Fe3O4 and BN-Fe3O4/SiC-Fe3O4 composites, owing to the aggregation of particles.

Amphiphilic Reactive Monomers for Automatic and Robust Vertical Alignment Layers of Liquid Crystals

윤원진,정광운 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

An amphiphilic reactive monomer consisting of a reactive itaconic acid for hydrophilic head and three alkyl chains for hydrophobic tail was designed and synthesized for the formation of automatic vertical alignment (VA) layer of nematic liquid crystal (NLC). Since a hydrophilic head was chemically attached to the end of amphiphilic reactive monomer, the amphiphilic reactive monomers initially dissolved in the host NLC. The alkyl chains of hydrophobic tail in the VA layer directly interacted with host NLC molecules and made them to automatically align vertically. After forming VA layer of host NLC, the VA layer can be stabilized. The polymerized VA layer exhibited a strong anchoring energy without generating any light scatterings. ** This work was supported by the BRL 2015042417, MOTIE/KDRC 10051334, Mid-Career Researcher Program (2016R1A2B2011041), and NRF-2017 Global Ph.D. Fellowship Program (NRF-2017H 1A 2A 1045855).