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Abadie, J.,Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M.,Accadia, T.,Acernese, F.,Adams, C.,Adhikari, R. X.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Ajith, P.,Allen, B.,Ceron, E. Amador,Amariutei, IOP Publishing 2012 The Astrophysical journal Vol.760 No.1
<P>We present the results of a search for gravitational waves associated with 154 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments in 2009-2010, during the sixth LIGO science run and the second and third Virgo science runs. We perform two distinct searches: a modeled search for coalescences of either two neutron stars or a neutron star and black hole, and a search for generic, unmodeled gravitational-wave bursts. We find no evidence for gravitational-wave counterparts, either with any individual GRB in this sample or with the population as a whole. For all GRBs we place lower bounds on the distance to the progenitor, under the optimistic assumption of a gravitational-wave emission energy of 10(-2) M-circle dot c(2) at 150 Hz, with a median limit of 17 Mpc. For short-hard GRBs we place exclusion distances on binary neutron star and neutron-star-black-hole progenitors, using astrophysically motivated priors on the source parameters, with median values of 16 Mpc and 28 Mpc, respectively. These distance limits, while significantly larger than for a search that is not aided by GRB satellite observations, are not large enough to expect a coincidence with a GRB. However, projecting these exclusions to the sensitivities of Advanced LIGO and Virgo, which should begin operation in 2015, we find that the detection of gravitational waves associated with GRBs will become quite possible.</P>
Microstructural Evolution and Mechanical Properties of Misch Metal Added Mg-Si Alloys
K. K. Ajith Kumar,U. T. S. Pillai,B. C. Pai,M. Chakraborty 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6
Effect of misch metal additions (0.3, 0.6, 0.9 and 1.2 wt%) on the refinement of Mg2Si phase in Mg-1.15Si alloy has been studied and compared with the base alloy. MM addition effectively refines the microstructure by breaking the α-Mg halos and lamellar eutectic phase and the maximum refinement is obtained for 0.6 MM addition. For higher MM additions (0.9 and 1.2 wt%), the refinement effect gets reduced and the formation of RE-Si compound is dominated. Improved tensile properties are obtained with the addition of MM and are attributed to the refinement of microstructure and the presence RE-Si compound. The tensile properties obtained are correlated with the microstructure and mirofractomechnisms.
Hysteresis Performance of Through Bolted Connections in Steel Beam to Circular CFST Column
M. S. Ajith,K. P. Beena,S. Sheela 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.7
Concrete Filled Steel Tubes (CFSTs) with through bolt connections are demonstrated to be satisfactory for seismic performance. Due to better confinement effect, circular CFST columns possess higher strength to weight ratio compared to square CFST. The only limiting factor in application of circular CFST in construction is the difficulty in joining with the beams. This paper presents an experimental study on hysteretic behavior of interior joint between circular CFST column and steel beam using extended end plates with through bolt. The study focuses on the comparison of connection using flat extended end plate with straight bolts and curved extended end plate with split bolt assembly for circular CFST columns. The experimental results were analysed in terms of strength, stiffness, ductility, failure mode and energy dissipation for the evaluation of cyclic performance. The results indicate that the seismic resistance agrees with seismic recommendations of American Institute of Steel Construction (AISC) and the split bolt assembly increases the performance remarkably. For comprehension of mechanism and prediction of shear capacity of the panel zone for curved endplates, a mathematical model was generated. This includes the influence of axial load, prestressing induced by bolt tightening, anchorage and the concrete strut action. The prediction accuracy was compared with the test result and it showed sound correlation.
Risk Factors for the Number of Sustained Injuries in Artisanal and Small-Scale Mining Operation
Ajith, Michael M.,Ghosh, Apurna K.,Jansz, Janis Occupational Safety and Health Research Institute 2020 Safety and health at work Vol.11 No.1
Background: The relationship between risk factors and likelihood of occupational injury has been studied. However, what has been published has only provided a limited explanation of why some of the employees working in the same environment as other employees suffered a single-injury event, while other employees experienced multiple-injury events. This article reports on an investigation of whether artisanal and small-scale miners in Migori County of Kenya are susceptible to a single-injury or multiple-injury incidences, and if so, what underpinning parameters explain the differences between the single incident injured and the multiple incident injured group. Mine management commitment to safety in artisanal and small-scale mining (ASM) operations is also considered. Materials and methods: The research objectives were achieved by surveying 162 uninjured and 74 injured miners. A structured, closed-end questionnaire was administered to participants after the stratification of the study population and systematic selection of the representative samples. Results: The results showed that most injured miners suffer a single-injury incident rather than experiencing multiple-injury events, and laceration (28.40%) was the common injury suffered by the miners. The analysis showed that the risk factors for the single incident injured group were not similar to those in the multiple incident injured group. The research also found mine workers have low opinion about mine management/owners commitment to safety. Conclusion: The study concluded that mine management and miners need to be educated and sensitized on the dangers of this operation. Provision of safety gears and positive safety culture must be a top priority for management.
M. Swedha,Abdulrahman A. Alatar,Mohammad K. Okla,Ibrahim A. Alaraidh,Asmaa Mohebaldin,Mohammed Aufy,Lija L. Raju,Ajith M. Thomas,Mostafa A. Abdel-Maksoud,S. Sudheer Khan 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.112 No.-
Visible light photocatalysis using nano heterostructures offers an eco-friendly alternative for the removalof organic molecules. Here, we reported an enhanced photocatalytic activity of g-C3N4/Ni3(VO4)2/ZnCr2O4, a dual Z-scheme nano-heterojunction for the photocatalytic removal of p-chlorophenol (p-CP)and 5-fluorouracil (5-FU). The nano heterojunction was fabricated by a facile co-precipitation method. Initially, the fabricated nanocomposites (NCs) were characterized for Physico-chemical and optoelectronicproperties, by XRD, XPS, SEM, TEM, UV–Visible DRS, BET, PL, and EIS. The fabricated g-C3N4/Ni3(VO4)2/ZnCr2O4 has shown excellent photocatalytic activity. The complete mineralization of both p-CP and 5-FU observed after 160 and 200 min of visible light irradiation respectively. The mineralizationof p-CP and 5-FU was confirmed by total organic carbon (TOC) estimation and the percentage of removalTOC for p-CP and 5-FU was 99.25% and 98.9% respectively. The stability of the particle was confirmed bysix cycles test. The reusable efficiency of the NCs was found to be 99.7% after six consequent cycles. Thestability of the NCs was confirmed by XRD and XPS analysis of reused photocatalyst. The scavengers assayand ESR analysis confirmed the major role of OH radicals in enhanced photocatalytic activity. The degradationpathway of p-CP and 5-FU was determined by GC–MS/MS and the possible toxicity of the intermediatecompounds was determined by the ECOSAR program, which shows the non-toxic nature ofthe end product on green algae, daphnia, and fish. The toxicity of the NCs was tested against Allium cepawhich further confirm the non-toxic nature of NCs. The study suggests that fabricated g-C3N4/Ni3(VO4)2/ZnCr2O4 NCs can be utilized for environmental remediation applications.
NUMERICAL FLOW VISUALIZATION ANALYSIS AROUND AN OSCILLATING SQUARE CYLINDER
M.K. Ju(주명근),R. Ajith Kumar,C.H. Sohn(손창현),R.H.L. Gowda 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
In this paper, a flow visualization analysis has been carried out on an oscillating square section cylinder, numerically, using a commercially available code CFD-ACE. In this study, the square cylinder is forced to oscillate at different frequencies of excitation, viz., fe/fo=0.5, 1.0 and 2.0 (where, fe is the excitation frequency provided to the cylinder and fo is the natural vortex shedding frequency from the stationary cylinder at a particular Reynolds number (=5200). In all the cases, the peak-to-peak amplitude of oscillation is kept at 32% of the side dimension of the square cylinder. These studies are conducted to understand the influence of frequency of oscillation on the flow field features around the cylinder, particularly the mode of vortex shedding. Results indicate that, the flow field around a square cylinder is very much influenced by the excitation frequency, in particular the vortex shedding mode. It is also found that, the vortex street parameters are significantly influence by the oscillation frequency. Comparison with earlier reported experimental studies has also been attempted in this paper. In appears that, such a numerical exercise (as performed in this paper) is first of its kind. It is believed that, these studies would enable one to understand the mechanisms underlying the flow-induced vibrations of a square section cylinder.
Strain induced structural transformation, mechanical and phonon stability in silicene derived 2D-SiB
Manju M.S.,Siby Thomas,Anees P.,Sang Uck Lee,Ajith K. M. 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.90 No.-
Two-dimensional monolayer SiB is a silicene derivative exhibiting buckling of atoms similar to that seenin silicene. This manuscript presents a systematic study of the strain-dependent variation of thestructural, mechanical, and dynamical properties of SiB. Strain was applied in the uniaxial armchair,uniaxial zigzag, and biaxial directions within the range of0.2 to 0.3. The resultant strain energy plotindicates anisotropic behavior of SiB in these directions. The SiB showed a mechanical strength that washigher than its counterpart, silicene, by an order of 30%. The elastic constant data from the undeformedSiB indicated an anisotropic nature, which was also seen with all the strain directions. Charge densitycontours, along with Bader charge analysis, confirmed the ionic nature of SiB in its original form. Thisnature became covalent as the strain varied from the compressive to the tensile regime in the uniaxialzigzag and biaxial directions. The majorfinding described in this manuscript is a newflat conformationhaving orthorhombic symmetry in contrast to the buckled structure. In addition, this material wasobserved to attain stability with the application of uniaxial tensile armchair and zigzag directionalstrains. Ab-initio molecular dynamics simulation confirmed the thermal stability of SiB in its newconformation.
Exploring the sensitivity of next generation gravitational wave detectors
Abbott, B P,Abbott, R,Abbott, T D,Abernathy, M R,Ackley, K,Adams, C,Addesso, P,Adhikari, R X,Adya, V B,Affeldt, C,Aggarwal, N,Aguiar, O D,Ain, A,Ajith, P,Allen, B,Altin, P A,Anderson, S B,Anderson, W Institute of Physics 2017 Classical and quantum gravity Vol.34 No.4
<P>The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe.</P>