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Search Results: 1 - 10 of 3509 matches for " Rwi Hau Lim "
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Hydrogen as Carbon Gasifying Agent During Glycerol Steam Reforming over Bimetallic Co-Ni Catalyst  [PDF]
Chin Kui Cheng, Rwi Hau Lim, Anabil Ubil, Sim Yee Chin, Jolius Gimbun
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.24B043
Abstract: Alumina-supported bimetallic cobalt-nickel catalyst has been prepared and employed in a fixed-bed reactor for the direct production of synthesis gas from glycerol steam reforming. Physicochemical properties of the 5Co-10Ni/85Al2O3 catalyst were determined from N2-physisorption, H2-chemisorption, CO2 and NH3-temperature-programmed desorption measurements as well as X-ray diffraction analysis. Both weak and strong acid sites are present on the catalyst surface. The acidic:basic ratio is about 7. Carbon deposition was evident at 923 K; addition of H2 however has managed to reduce the carbon deposition. Significantly, this has resulted in the increment of CH4 formation rate, consistent with the increased carbon gasification and methanation. Carbon deposition was almost non-existent, particularly at 1023 K. In addition, the inclusion of hydrogen also has contributed to the decrease of CO2 and increase of CO formation rates. This was attributed to the reverse water-gas-shift reaction. Overall, both the CO2:CO and CO2:CH4 ratios decrease with the hydrogen partial pressure.
Spin-wave nonreciprocity based on interband magnonic transitions
Kai Di,Hock Siah Lim,Vanessa Li Zhang,Ser Choon Ng,Meng Hau Kuok
Physics , 2013, DOI: 10.1063/1.4822095
Abstract: We theoretically demonstrate linear spin-wave nonreciprocity in a Ni80Fe20 nanostripe waveguide, based on interband magnonic transitions induced by a time-reversal and spatialinversion symmetry breaking magnetic field. An analytical coupled-mode theory of spin waves, developed to describe the transitions which are accompanied by simultaneous frequency and wavevector shifts of the coupled spin waves, is well corroborated by numerical simulations. Our findings could pave the way for the realization of spin-wave isolation and the dynamic control of spin-wave propagation in nanoscale magnonic integrated circuits via an applied magnetic field.
Asymmetric spin-wave dispersion due to Dzyaloshinskii-Moriya interaction in an ultrathin Pt/CoFeB film
Kai Di,Vanessa Li Zhang,Hock Siah Lim,Ser Choon Ng,Meng Hau Kuok,Xuepeng Qiu,Hyunsoo Yang
Physics , 2014, DOI: 10.1063/1.4907173
Abstract: Employing Brillouin spectroscopy, strong interfacial Dzyaloshinskii-Moriya interactions have been observed in an ultrathin Pt/CoFeB film. Our micromagnetic simulations show that spin-wave nonreciprocity due to asymmetric surface pinning is insignificant for the 0.8nmthick CoFeB film studied. The observed high asymmetry of the monotonic spin wave dispersion relation is thus ascribed to strong Dzyaloshinskii-Moriya interactions present at the Pt/CoFeB interface. Our findings should further enhance the significance of CoFeB as an important material for magnonic, spintronic and skyrmionic applications.
Band structure of magnonic crystals with defects: Brillouin spectroscopy and micromagnetic simulations
Kai Di,Vanessa Li Zhang,Meng Hau Kuok,Hock Siah Lim,Ser Choon Ng,Kulothungasagaran Narayanapillai,Hyunsoo Yang
Physics , 2014, DOI: 10.1103/PhysRevB.90.060405
Abstract: Using Brillouin spectroscopy, the first observation has been made of the band structures of nanostructured defect magnonic crystals. The samples are otherwise one-dimensional periodic arrays of equal-width Ni80Fe20 and cobalt nanostripes, where the defects are stripes of a different width. A dispersionless defect branch emerges within the bandgap with a frequency tunable by varying the defect stripe width, while the other branches observed are similar to those of a defect-free crystal. Micromagnetic and finite-element simulations performed unveil additional tiny bandgaps and the frequency-dependent localization of the defect mode in the vicinity of the defects.
Phononic and magnonic dispersions of surface waves on a permalloy/BARC nanostructured array
Huihui Pan, Vanessa Li Zhang, Kai Di, Meng Hau Kuok, Hock Siah Lim, Ser Choon Ng, Navab Singh and Adekunle Olusola Adeyeye
Nanoscale Research Letters , 2013, DOI: 10.1186/1556-276X-8-115
Abstract: Phononic and magnonic dispersions of a linear array of periodic alternating Ni80Fe20 and bottom anti-reflective coating nanostripes on a Si substrate have been measured using Brillouin light scattering. The observed phononic gaps are considerably larger than those of laterally patterned multi-component crystals previously reported, mainly a consequence of the high elastic and density contrasts between the stripe materials. Additionally, the phonon hybridization bandgap has an unusual origin in the hybridization and avoided crossing of the zone-folded Rayleigh and pseudo-Sezawa waves. The magnonic band structure features near-dispersionless branches, with unusual vortex-like dynamic magnetization profiles, some of which lie below the highly-dispersive fundamental mode branch. Finite element calculations of the phononic and magnonic dispersions of the magphonic crystal accord well with experimental data.
In-plane angular dependence of the spin-wave nonreciprocity of an ultrathin film with Dzyaloshinskii-Moriya interaction
Vanessa Li Zhang,Kai Di,Hock Siah Lim,Ser Choon Ng,Meng Hau Kuok,Jiawei Yu,Jungbum Yoon,Xuepeng Qiu,Hyunsoo Yang
Physics , 2015, DOI: 10.1063/1.4926862
Abstract: The nonreciprocal propagation of spin waves in an ultrathin Pt/Co/Ni film has been measured by Brillouin light scattering. The frequency nonreciprocity, due to the interfacial Dzyaloshinskii-Moriya interaction (DMI), has a sinusoidal dependence on the in-plane angle between the magnon wavevector and the applied magnetic field. The results, which are in good agreement with analytical predictions reported earlier, yield a value of the DMI constant which is the same as that obtained previously from a study of the magnon dispersion relations. We have demonstrated that our magnon-dynamics based method can experimentally ascertain the DMI constant of multilayer thin films.
Direct observation of the Dzyaloshinskii-Moriya interaction in a Pt/Co/Ni film
Kai Di,Vanessa Li Zhang,Hock Siah Lim,Ser Choon Ng,Meng Hau Kuok,Jiawei Yu,Jungbum Yoon,Xuepeng Qiu,Hyunsoo Yang
Physics , 2014, DOI: 10.1103/PhysRevLett.114.047201
Abstract: The interfacial Dzyaloshinskii-Moriya interaction (DMI) in an in-plane anisotropic Pt(4nm)/Co(1.6nm)/Ni(1.6nm) film has been directly observed by Brillouin spectroscopy. It is manifested in the asymmetry of the measured magnon dispersion relation, from which the DMI constant has been evaluated. Linewidth measurements reveal that the lifetime of the magnons is asymmetric with respect to their counter-propagating directions. The lifetime asymmetry is dependent on the magnon frequency, being more pronounced the higher the frequency. Analytical calculations of the magnon dispersion relation and linewidth agree well with experiments.
A Local Currency in a Dollarized Economy  [PDF]
Sokchea Lim
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.35086
Abstract: The paper uses a dual-currency search theoretic approach to demonstrate that it is possible to induce the acceptance of a local currency in a dollarized economy. In the model, we assume that a foreign currency is in full circulation and the government policy tool is the convertibility of the local currency to the foreign currency. We show that the economy can achieve equilibria where two monies are in circulation if the government can raise a sufficiently high probability of exchange between the two currencies.
Taijin-Kyofu-Sho: A subtype of social anxiety  [PDF]
Leslie Lim
Open Journal of Psychiatry (OJPsych) , 2013, DOI: 10.4236/ojpsych.2013.34042
Abstract:

Taijin-Kyofu-Sho (TKS) has long been considered as a Japanese culture-bound form of social anxiety disorder, although subsequent case-reports from countries outside Japan have dispelled this notion. There are subtle yet distinct differences between TKS and DSM-defined social anxiety disorder (SAD). For instance, the TKS subject fears causing offence to others, whereas the SAD subject is more fearful of causing embarrassment to him/herself. Four sub-categories of TKS have been recognised of which the Jikoshu-kyofu variety resembles the olfactory reference syndrome (ORS) known to Western psychiatrists. There are two TKS subtypes, general (or simple) and offensive (delusional). The general subtype resembles social anxiety disorder, whereas the offensive subtype is characterised by delusions. True community-wide prevalence is unknown, although clinic studies estimate between 7.8% to 45.5% patients have a diagnosis of TKS, with a slight male preponderance. Cultural and societal norms engendering guilt, shame, and embarrassment are likely etiological factors. Treatment may consist of antidepressant and/or antipsychotic medications, while some patients may also benefit from cognitive behavior therapy.

An Analysis of the Jonsei and Purchase Prices in the Korean Housing Market  [PDF]
Gieyoung Lim
Modern Economy (ME) , 2015, DOI: 10.4236/me.2015.61007
Abstract: The primary purpose of this paper is to construct and estimate an econometric model for the Jonsei-to-Purchase price ratio (JPR), and to draw implications for the development in the Korean housing market. In particular, we are interested in: a) identifying regimes across which the ratio shows markedly different dynamic behavior; and b) drawing implications from the model for the recent increases in the ratio. Estimation of the model for the period 1987:Q1-2011:Q3 confirms the presence of two different regimes: one with the zero trend in the JPR, and the other with positive trend. Furthermore, it is found that cyclical variations play nontrivial role only in the first regime, while the movements of the JPR in the other regime are mostly governed by the trend component. We also find that the cyclical deviations of the ratio from its trend are corrected, if any, by the changes in the future purchase price.
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