Application of numerical models to determine wind uplift ratings of roofs

Baskaran, A.,Borujerdi, J. Techno-Press 2001 Wind and Structures, An International Journal (WAS Vol.4 No.3

Wind uplift rating of roofing systems is based on standardised test methods. Roof specimens are placed in an apparatus with specified table size (length and width) then subjected to the required wind load cycle. Currently, there is no consensus on the table size to be used by these testing protocols in spite of the fact that a table size plays a significant role in evaluating the performance. This paper presents a study with the objective to investigate the impact of table size on the performance of roofing systems. To achieve this purpose, extensive numerical experiments using the finite element method have been conducted to investigate the performance of roofing systems subjected to wind uplift pressures. Numerical results were compared with results obtained from experimental work to benchmark the numerical modeling. Required table size and curves for the determinations of appropriate correction factors are suggested. This has been completed for various test configurations with thermoplastic waterproofing membranes. Development of correction factors for assemblies with thermoset and modified bituminous membranes are in progress. Generalization of the correction factors and its usage for wind uplift rating of roofs will be the focus of a future paper.

A New Cascaded Multilevel Inverter Topology with Voltage Sources Arranged in Matrix Structure

Thamizharasan. S,Baskaran. J,Ramkumar. S 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

The paper unleashes a new idea to arrive at reduced switch count topological structures configured in the form of a matrix for a cascaded Multi level inverter (CMLI). The theory encircles to minimize the number of switches involved in the conduction path and there from acclaim reduced input current distortion, lower switching losses and electromagnetic interference. The focus extends to standardize the number of power devices required for reaching different levels of output voltage from the same architecture. It includes appropriate pulse width modulation (PWM) strategy to generate firing pulses and ensure the desired operation of the power modules. The investigative study carries with it MATLAB based simulation and experimental results obtained using suitable prototypes to illustrate the viability of the proposed concept. The promising nature of the performance projects a new dimension in the use of single phase MLIs for renewable energy related applications.

Large scale patternable 3-dimensional carbon nanotube-graphene structure for flexible Li-ion battery

Kang, C.,Baskaran, R.,Hwang, J.,Ku, B.C.,Choi, W. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.68 No.-

There has been strong interest in flexible, lightweight and reliable rechargeable batteries to meet the requirements of today's portable devices. To build such flexible rechargeable batteries with high efficiency, new architectures for current collectors need to be developed. The porous 3-dimensional (3D) electrode architecture has been proposed to increase the efficiency of a Li-ion battery by using its higher surface area, shorter diffusion path and higher volumetric capacity than those of 2D electrodes. Herein we fabricated an array structure of 3D multiwall carbon nanotubes (MWCNTs)-graphene on transparent and flexible polyethylene terephthalate (PET) film through a simple lamination process. The transferred 3D column structure of MWCNTs onto graphene-PET film showed structural integrity and low contact resistance at high angle bending. The new flexible 3D MWCNTs-graphene-PET electrode yielded excellent C-rate capability and specific capacity with high Coulombic efficiency of over 99%. The novel 3D MWCNTs-graphene nanostructure fabricated on flexible film could provide a wide range of applications in next-generation flexible and light weight batteries and energy storages.

Effect of saturated fatty acids on tacrolimus-loaded liquid crystalline nanoparticles

( R K Thapa ),( R Baskaran ),( T Madheswaran ),( J Y Rhyu ),( J O Kim ),( C S Yong ),( B K Yoo ) 영남대학교 약품개발연구소 2013 영남대학교 약품개발연구소 연구업적집 Vol.23 No.0

Liquid crystalline nanoparticles are unique structures that can be used in the delivery of a wide range of pharmaceutical actives. Herein, we studied the effect of saturated fatty acids on tacrolimus-loaded monoolein liquid crystalline nanoparticles stabilized with poloxamer 407, Char-acterization of nanoparticles included optical and transmission electron microscopy, particle size, and entrapment efficiency analysis. Microscope data suggested the formation of cubosomes for monoolein dispersions, and of hexosomes for monoolein-fatty caid systems. Entrapment efficiency of tacrolimus was as high as 99% or above. In vitro release study revealed that amount of monoolein and carbon chain lengths of the fatty acid were the factors that affected drug release from the liquid crystalline nanoparticles. Notably, monoolein-fatty acid systems prepared with short chain length, such as lauric and myristic acid, showed markedly sustained release profile of the drug. Hence, appropriate selection of fatty acid can be exploited to achieve desired release profile from monooloein liquid crystalline nanoparticles.

In vitro release and skin permeation of tacrolimus from monoolein-based liquid crystalline nanoparticles

( R K Thapa ),( R Baskaran ),( T Madheswaran ),( J O Kim ),( C S Yong ),( B K Yoo ) 영남대학교 약품개발연구소 2013 영남대학교 약품개발연구소 연구업적집 Vol.23 No.0

The objective of the present study was to determine the effect of different ratios of monoolein and oleic aciad on in vitro release and ski permeation of tacrolimus from monoolein-based liquid crystalline nanoparticles. The nanoparticles were prepared by sonicating a mixture of melted monoolein, poloxamer 407, oleic acid and tacrolimus to which distilled water was added. Formation of cubosomes and hexosomes was confirmed by transmission electron microscopy and optical microscopy, and average particle size of the formulations was about 150-200 nm. The encapsulation effeciency for tacrolims in all the formulations was > 99%. In vitro retro release of the drug was proportionally reduced by the amount of monoolein used. Addition of oleic acid further reduced the tacrolimus release. The skin permeation was also in agreement with the vitro release. This study provides a strategy to control the release and skin permeation of tacrolimus from nanoparticles, thus expanding the area of tacrolimus usage.

MODELING AND ANALYSIS OF A FUEL-INJECTION PUMP USED IN DIESEL ENGINES

P. SUNDARRAMAN,S. K. SAHA,N. J. VASA3,R. BASKARAN,V. SUNILKUMAR,K. RAGHAVENDRA 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.2

The Fuel-Injection Pump (FIP) used in diesel engine has a higher-pair cam-mechanism to pressurize the fuel for injection. This paper proposes a methodology to model FIP from a multibody Dynamics (MBD) perspective. The results from the model include the temporal behavior of driving torque, contact Hertz stress and reaction forces at various joints. The model helps the designer to assess the effect of various cam profiles, link parameters and other design variables. It is necessary that these parameters be optimized for future high pressure applications. For this purpose, a cam-mechanism with offset follower axis is analysed. Decoupled Natural Orthogonal Complement (DeNOC) matrices based algorithm is used to model FIP without and with offset cam-mechanism. The study shows that, the offset cam-mechanism allows reduction in the sidethrust, reaction forces, and the contact Hertz stress acting on the cam-follower interface. As a typical case, for an FIP working around a pressure value of 600 bar, an optimum offset value is found to be 9.5 mm and it shows a reduction of about 45% in side thrust values. To validate the modeling approach, experimental studies are performed on pump without and with offset cam-mechanism. Experimental results are in qualitative agreement with the theoretical model results.

Flexible Dispatch Strategy Adopted by Optimizing DG Parameters in a Real Time Power System Distributed Network

Shanmugapriya P.,Kumaran M. Senthil,Baskaran J.,Nayanatara C.,Sharmila P.,Eltamaly Ali M. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

Demand response management (DRM) aims to curb the energy consumption by reducing the peak load and thereby improve the performance of distributed generation (DG). From the utility perspective, the cost of generation should be kept minimum, whereas from the customer’s view, the social welfare should be maximum. Therefore this research focuses on a new method based on intelligent algorithm to optimally operate the demand side management in the presence of DG units and demand response. Initially, the location, size and rating of DG units are selected to achieve the optimization of real, reactive power and voltage deviation Index. Finally comprehensive case studies are taken into consideration with DRM strategy to vindicate the technical and economical benefi ts. Reduction in congestion and power loss with maximized customer benefi t are taken as an objective function in this stage. Probability-Based Incremental Learning is implemented and it is tested in a standard IEEE 33bus system and a real-time Indian utility 23-bus system. Results reveal that the proposed optimization technique ensures better performance, reliability, and effi ciency even under parameter variations to prove the superiority of the proposed strategy

Sialic Acid Engineering : Characterization of the metabolic flux and apoptotic effects of N-acetylmannosamime (ManNAc) analogs

Eun Jeong Kim(김은정),Srinivasa-Gopalan Sampathkumar,Mark B. Jones,Jun Kyu Rhee,Gautam Baskaran,Kevin J, Yarema 한국생물공학회 2004 한국생물공학회 학술대회 Vol.2004 No.4

Quantitative measurement of lipid rich plaque by coronary computed tomography angiography: A correlation of histology in sudden cardiac death

Han, Donghee,Torii, Sho,Yahagi, Kazuyuki,Lin, Fay Y.,Lee, Ji Hyun,Rizvi, Asim,Gransar, Heidi,Park, Mahn-Won,Roudsari, Hadi Mirhedayati,Stuijfzand, Wijnand J.,Baskaran, Lohendran,ó,Hartaigh, Br&i Elsevier Scientific Publ. Co 2018 Atherosclerosis Vol. No.

<P><B>Abstract</B></P> <P><B>Background and aims</B></P> <P>Recent advancements in coronary computed tomography angiography (CCTA) have allowed for the quantitative measurement of high-risk lipid rich plaque. Determination of the optimal threshold for Hounsfield units (HU) by CCTA for identifying lipid rich plaque remains unknown. We aimed to validate reliable cut-points of HU for quantitative assessment of lipid rich plaque.</P> <P><B>Methods</B></P> <P>8 post-mortem sudden coronary death hearts were evaluated with CCTA and histologic analysis. Quantitative plaque analysis was performed in histopathology images and lipid rich plaque area was defined as intra-plaque necrotic core area. CCTA images were analyzed for quantitative plaque measurement. Low attenuation plaque (LAP) was defined as any pixel < 30, 45, 60, 75, and 90 HU cut-offs within a coronary plaque. The area of LAP was calculated in each cross-section.</P> <P><B>Results</B></P> <P>Among 105 cross-sections<B>,</B> 37 (35.2%) cross-sectional histology images contained lipid rich plaque. Although the highest specificity for identifying lipid rich plaque was shown with <30 HU cut-off (88.2%), sensitivity (e.g. 55.6% for <75 HU, 16.2% for <30 HU) and negative predictive value (e.g. 75.9% for <75 HU, 65.9% for <30 HU) tended to increase with higher HU cut-offs. For quantitative measurement, <75 HU showed the highest correlation coefficient (0.292, <I>p</I> = 0.003) and no significant differences were observed between lipid rich plaque area and LAP area between histology and CT analysis (Histology: 0.34 ± 0.73 mm<SUP>2</SUP>, QCT: 0.37 ± 0.71 mm<SUP>2</SUP>, <I>p</I> = 0.701).</P> <P><B>Conclusions</B></P> <P>LAP area by CCTA using a <75 HU cut-off value demonstrated high sensitivity and quantitative agreement with lipid rich plaque area by histology analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lipid rich plaques are related to future risk of acute coronary syndrome. </LI> <LI> Quantitative coronary plaque (QCT) analysis enables to quantify lipid rich plaques. </LI> <LI> 75 HU is a reliable cut-off for quantification of lipid rich plaque in QCT analysis. </LI> </UL> </P>