An analytical study on the static vertical stiffness of wire rope isolators

P. S. Balaji,Leblouba Moussa,M. E. Rahman,Lau Hieng Ho 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1

The vibrations caused by earthquake ground motions or the operations of heavy machineries can affect the functionality of equipmentand cause damages to the hosting structures and surrounding equipment. A Wire rope isolator (WRI), which is a type of passive isolatorknown to be effective in isolating shocks and vibrations, can be used for vibration isolation of lightweight structures and equipment. Theprimary advantage of the WRI is that it can provide isolation in all three planes and in any orientation. The load-supporting capability ofthe WRI is identified from the static stiffness in the loading direction. Static stiffness mainly depends on the geometrical and materialproperties of the WRI. This study develops an analytical model for the static stiffness in the vertical direction by using Castigliano’s secondtheorem. The model is validated by using the experimental results obtained from a series of monotonic loading tests. The flexuralrigidity of the wire ropes required in the model is obtained from the transverse bending test. Then, the analytical model is used to conducta parametric analysis on the effects of wire rope diameter, width, height, and number of turns (loops) on vertical stiffness. The wire ropediameter influences stiffness more than the other geometric parameters. The developed model can be accurately used for the evaluationand design of WRIs.

From BASE-ASIA toward 7-SEAS: A satellite-surface perspective of boreal spring biomass-burning aerosols and clouds in Southeast Asia

Tsay, S.C.,Hsu, N.C.,Lau, W.K.M.,Li, C.,Gabriel, P.M.,Ji, Q.,Holben, B.N.,Judd Welton, E.,Nguyen, A.X.,Janjai, S.,Lin, N.H.,Reid, J.S.,Boonjawat, J.,Howell, S.G.,Huebert, B.J.,Fu, J.S.,Hansell, R.A.,S Pergamon Press ; Elsevier [distribution] 2013 Atmospheric environment Vol.78 No.-

In this paper, we present recent field studies conducted by NASA's SMART-COMMIT (and ACHIEVE, to be operated in 2013) mobile laboratories, jointly with distributed ground-based networks (e.g., AERONET, http://aeronet.gsfc.nasa.gov/ and MPLNET, http://mplnet.gsfc.nasa.gov/) and other contributing instruments over northern Southeast Asia. These three mobile laboratories, collectively called SMARTLabs (cf. http://smartlabs.gsfc.nasa.gov/, Surface-based Mobile Atmospheric Research &Testbed Laboratories) comprise a suite of surface remote sensing and in-situ instruments that are pivotal in providing high spectral and temporal measurements, complementing the collocated spatial observations from various Earth Observing System (EOS) satellites. A satellite-surface perspective and scientific findings, drawn from the BASE-ASIA (2006) field deployment as well as a series of ongoing 7-SEAS (2010-13) field activities over northern Southeast Asia are summarized, concerning (i) regional properties of aerosols from satellite and in-situ measurements, (ii) cloud properties from remote sensing and surface observations, (iii) vertical distribution of aerosols and clouds, and (iv) regional aerosol radiative effects and impact assessment. The aerosol burden over Southeast Asia in boreal spring, attributed to biomass burning, exhibits highly consistent spatial and temporal distribution patterns, with major variability arising from changes in the magnitude of the aerosol loading mediated by processes ranging from large-scale climate factors to diurnal meteorological events. Downwind from the source regions, the tightly coupled-aerosol-cloud system provides a unique, natural laboratory for further exploring the micro- and macro-scale relationships of the complex interactions. The climatic significance is presented through large-scale anti-correlations between aerosol and precipitation anomalies, showing spatial and seasonal variability, but their precise cause-and-effect relationships remain an open-ended question. To facilitate an improved understanding of the regional aerosol radiative effects, which continue to be one of the largest uncertainties in climate forcing, a joint international effort is required and anticipated to commence in springtime 2013 in northern Southeast Asia.

Artificial Intelligence for Adult Spinal Deformity

Rushikesh S. Joshi,Alexander F. Haddad,Darryl Lau,Christopher P. Ames 대한척추신경외과학회 2019 Neurospine Vol.16 No.4

Adult spinal deformity (ASD) is a complex disease that significantly affects the lives of many patients. Surgical correction has proven to be effective in achieving improvement of spinopelvic parameters as well as improving quality of life (QoL) for these patients. However, given the relatively high complication risk associated with ASD correction, it is of paramount importance to develop robust prognostic tools for predicting risk profile and outcomes. Historically, statistical models such as linear and logistic regression models were used to identify preoperative factors associated with postoperative outcomes. While these tools were useful for looking at simple associations, they represent generalizations across large populations, with little applicability to individual patients. More recently, predictive analytics utilizing artificial intelligence (AI) through machine learning for comprehensive processing of large amounts of data have become available for surgeons to implement. The use of these computational techniques has given surgeons the ability to leverage far more accurate and individualized predictive tools to better inform individual patients regarding predicted outcomes after ASD correction surgery. Applications range from predicting QoL measures to predicting the risk of major complications, hospital readmission, and reoperation rates. In addition, AI has been used to create a novel classification system for ASD patients, which will help surgeons identify distinct patient subpopulations with unique risk-benefit profiles. Overall, these tools will help surgeons tailor their clinical practice to address patients’ individual needs and create an opportunity for personalized medicine within spine surgery.

Artificial Intelligence and the Future of Spine Surgery

Rushikesh S. Joshi,Darryl Lau,Christopher P. Ames 대한척추신경외과학회 2019 Neurospine Vol.16 No.4

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Carbon nanofibers and multiwalled carbon nanotubes from camphor and their field electron emission

Savita P. Somani,Prakash R. Somani,M. Tanemura,S.P. Lau,M. Umeno 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Vertically aligned carbon nanofibers (CNF) and multiwalled carbon nanotubes (MWCN) have been synthesized from camphor by catalytic thermal CVD method on Co and Co/Fe thin films (for CNF) and on silicon substrates using a mixture of camphor and ferrocene (for MWCN). CNF and MWCN are studied by field emission scanning electron microscopy, high-resolution transmission electron microscopy, visible Raman spectroscopy, X-ray diffraction in order to get insight into the microstructure and morphology of these materials. Field electron emission study indicates turn-on field of about 2.56, 3.0 and 6.5 V/㎛ for MWCN, Co/CNF and Co/Fe/CNF films, respectively. The best performance of MWCN in field electron emission among the materials studied can be due to the highest aspect ratio, good graphitization and good density. Vertically aligned carbon nanofibers (CNF) and multiwalled carbon nanotubes (MWCN) have been synthesized from camphor by catalytic thermal CVD method on Co and Co/Fe thin films (for CNF) and on silicon substrates using a mixture of camphor and ferrocene (for MWCN). CNF and MWCN are studied by field emission scanning electron microscopy, high-resolution transmission electron microscopy, visible Raman spectroscopy, X-ray diffraction in order to get insight into the microstructure and morphology of these materials. Field electron emission study indicates turn-on field of about 2.56, 3.0 and 6.5 V/㎛ for MWCN, Co/CNF and Co/Fe/CNF films, respectively. The best performance of MWCN in field electron emission among the materials studied can be due to the highest aspect ratio, good graphitization and good density.

Low-dimensional modelling of n-type doped silicene and its carrier transport properties for nanoelectronic applications

Chuan, M.W.,Lau, J.Y.,Wong, K.L.,Hamzah, A.,Alias, N.E.,Lim, C.S.,Tan, M.L.P Techno-Press 2021 Advances in nano research Vol.10 No.5

Silicene, a 2D allotrope of silicon, is predicted to be a potential material for future transistor that might be compatible with present silicon fabrication technology. Similar to graphene, silicene exhibits the honeycomb lattice structure. Consequently, silicene is a semimetallic material, preventing its application as a field-effect transistor. Therefore, this work proposes the uniform doping bandgap engineering technique to obtain the n-type silicene nanosheet. By applying nearest neighbour tight-binding approach and parabolic band assumption, the analytical modelling equations for band structure, density of states, electrons and holes concentrations, intrinsic electrons velocity, and ideal ballistic current transport characteristics are computed. All simulations are done by using MATLAB. The results show that a bandgap of 0.66 eV has been induced in uniformly doped silicene with phosphorus (PSi₃NW) in the zigzag direction. Moreover, the relationships between intrinsic velocity to different temperatures and carrier concentration are further studied in this paper. The results show that the ballistic carrier velocity of PSi₃NW is independent on temperature within the degenerate regime. In addition, an ideal room temperature subthreshold swing of 60 mV/dec is extracted from ballistic current-voltage transfer characteristics. In conclusion, the PSi₃NW is a potential nanomaterial for future electronics applications, particularly in the digital switching applications.