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61.
After 104 h of continuous aqueous electrolysis with K2CO3 as the electrolyte, highly stable novel inorganic hydride compounds such as KH KHCO3 and KH were isolated and identified by time of flight secondary ion mass spectroscopy (ToF-SIMS). The existence of novel hydride ions was determined using X-ray photoelectron spectroscopy (XPS) and solid state magic-angle spinning proton nuclear magnetic resonance spectroscopy (1H MAS NMR). A novel hydride ion formed by plasma electrolysis of a K2CO3, Rb2CO3, or Cs2CO3 electrolyte was also observed by high resolution visible spectroscopy at 407.0 nm corresponding to its predicted binding energy of 3.05 eV. 相似文献
62.
Adam Jacobson Fan Zeng David Smith Nigel Boswell Thierry Peynot Michael Milford 《野外机器人技术杂志》2021,38(1):5-27
Robustly and accurately localizing vehicles in underground mines is particularly challenging due to the unavailability of GPS, variable and often poor lighting conditions, visual aliasing in long tunnels, and airborne dust and water. In this paper, we present a novel, infrastructure‐less, multisensor localization method for robust autonomous operation within underground mines. The proposed method integrates with existing mine site commissioning and operation procedures and includes both an offline map‐building process and an online localization algorithm. The approach combines the strengths of visual‐based place recognition, LIDAR‐based localization, and odometry in a particle filter fusion process. We provide an extensive experimental validation using new large data sets acquired in two operational Australian underground hard‐rock mines (including a 600m‐deep multilevel mine with approximately 33 km of mapping data and 7 km of vehicle localization) by actual mining vehicles during production operations. We demonstrate a significant increase in localization accuracy over prior state‐of‐the‐art SLAM research systems and real‐time operation, with processing times in the order of 10 Hz. We present results showing a mean error of 0.68 m from the Queensland Mine data set and 1.32 m from the New South Wales Mine data set and at least 86% reduction in error compared with prior state of the art. We also analyze the impact of the particle filter parameters with respect to localization accuracy. Together this study represents a new approach to positioning systems for currently deployed autonomous vehicles within underground mine environments. 相似文献
63.
Soubhik De Abhinav Omprakash Fulmali Krishna Chaitanya Nuli Rajesh Kumar Prusty B. Gangadhara Prusty Bankim Chandra Ray 《应用聚合物科学杂志》2021,138(15):50208
In this article, modification of carbon fiber surface by carbon based nanofillers (multi-walled carbon nanotubes [CNT], carbon nanofibers, and multi-layered graphene) has been achieved by electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in-situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter-laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in-situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites. 相似文献
64.
Soubhik De P.N. Shivangi Saswat Choudhury Abhinav Omprakash Fulmali Bankim Chandra Ray Rajesh Kumar Prusty 《应用聚合物科学杂志》2021,138(42):51231
Carbon fiber reinforced epoxy (CE) composite is ideal for a cryogenic fuel storage tank in space applications due to its unmatched specific strength and modulus. In this article, inter-laminar shear strength (ILSS) of carbon fiber/epoxy (CE) composite is shown to be considerably improved by engineering the interface with carboxyl functionalized multi-walled carbon nanotube (FCNT) using electrophoretic deposition technique. FCNT deposited fibers from different bath concentrations (0.3, 0.5, and 1.0 g/L) were used to fabricate the laminates, which were then tested at room (30°C) and in-situ liquid nitrogen (LN) (−196°C) temperature as well as conditioning for different time durations (0.25, 0.5, 1, 6, and 12 h) followed by immediate RT testing to study the applicability of these engineered materials at the cryogenic environment. A maximum increment in ILSS was noticed at bath concentration of 0.5 g/L, which was ~21% and ~ 17% higher than neat composite at 30°C and − 196°C, respectively. Short-term LN conditioning was found to be detrimental due to developed cryogenic shock, which was further found to be compensated by cryogenic interfacial clamping upon long-term exposure. 相似文献
65.
Pavan Kumar Gangineni Satyaroop Patnaik Rajesh Kumar Prusty Bankim Chandra Ray 《应用聚合物科学杂志》2021,138(46):51365
The study aims at investigating the mechanical behavior of carbon fiber reinforced polymer (CFRP) composites modified with graphene carboxyl at elevated temperature (ET-110°C) and understanding the effect of electrophoretic deposition bath concentration (0.5 g/L, 1.0 g/L, and 1.5 g/L) on their mechanical behavior at ET. The 1.5 g/L composite has revealed a maximum improvement in energy absorbed before failure of 33.25% at RT and 22.54% at ET for flexural testing and ∼35% at RT for short beam shear testing, over neat CFRP composite. The modified composites have shown an improved flexural strain to failure at both RT and ET, with 1.5 g/L composite exhibiting maximum enhancement of 12.41% at RT and 26.52% at ET over neat composite. However, at ET, modified composites exhibited lower flexural strength and interlaminar shear strength values in comparison to that of neat. Viscoelastic behavior of all composites was studied to understand bath concentration's effect on thermal behavior via dynamic mechanical thermal analysis. Differential scanning calorimetry was employed for governing the glass transition temperature of composites. Fractography of tested samples (both ET and RT) was performed utilizing a scanning electron microscope to determine the prominent failure mode. 相似文献
66.
Jayita Bandyopadhyay Caroline Mekoa Dimakatso Makwakwa Sifiso Skosana Suprakas Sinha Ray 《Polymer Engineering and Science》2021,61(4):1195-1208
The development of a reactively processed polypropylene nanocomposite (PPNC) with consequential improvements in the heat deflection temperature (HDT), Vicat softening temperature (VST), and crystallization peak temperature (Tc) is reported herein. Neat PP without nanoclay was also reactively processed to elucidate the effects of fillers on the improvement in physical properties. The results show a considerable improvement in the HDT of PPNC (77.9 °C) compared to those of neat PP (62.6 °C) and reactively processed branched PP (BPP; 69.2 °C). Moreover, the Tc of PP in PPNC improved by ~14% compared to that of neat PP. Various models of nonisothermal crystallization kinetics were employed to elucidate the nucleation and crystal growth mechanisms, and to correlate them with the observed HDT improvement in PPNC. Thermal transitions investigated by modulated differential scanning calorimetry explained the changes observed in the VSTs of all the samples. To the best of our knowledge, this is the first report on a significant improvement in HDT along with a marked increase in Tc. Such simultaneous improvements in HDT, VST, and Tc are highly desirable for applications involving the use of PP-based materials in rigid packaging. 相似文献
67.
Uma Batra S. Ray S. R. Prabhakar 《Journal of Materials Engineering and Performance》2003,12(5):597-601
A ductile iron containing 0.6% copper as the main alloying element was austempered at a fixed austempering temperature of
330 °C for a fixed austempering time of 60 min after austenitization at 850 °C for different austenitization periods of 60,
90, and 120 min. The austempering process was repeated after changing austenitization temperature to 900 °C. The effect of
austenitization temperature and time was studied on the carbon content and its distribution in the austenite after austenitization.
The effect of austenitization parameters was also studied on austempered microstructure, structural parameters like volume
fraction of austenite, X
γ
, carbon content C
γ
, and X
γ
C
γ
, and bainitic ferrite needle size, d
α
after austempering. The average carbon content of austenite increases linearly with austenitization time and reaches a saturation
level. Higher austenitization temperature results in higher carbon content of austenite. As regards the austempered structure,
the lowering austenitization temperature causes significant refinement and more uniform distribution of austempered structure,
and a decrease in the volume fraction of retained austenite. 相似文献
68.
In the present investigation, the effect of alloying elements on the austempering process, austempered microstructure, and
structural parameters of two austempered ductile irons (ADI) containing 0.6% Cu and 0.6% Cu/1.0% Ni as the main alloying elements
was investigated. The optical metallography and x-ray diffraction were used to study the changes in the austempered structure.
The effect of alloying additions on the austempering kinetics was studied using the Avrami equation. Significantly more upper
bainite was observed in the austempered Cu-Ni alloyed ADI than in Cu alloyed ADI. The volume fraction of retained austenite
(X
γ), the carbon level in the retained austenite (C
γ), and the product X
γ
C
γ in an austempered structure of Cu-alloyed ADI are higher than in Cu-Ni-alloyed ADI. The austempering Kinetics is slowed down
by the addition of Ni. 相似文献
69.
S. K. Albert C. R. Das V. Ramasubbu A. K. Bhaduri S. K. Ray Baldev Raj 《Journal of Materials Engineering and Performance》2002,11(3):243-249
A root-cracked blade in a high-pressure steam turbine of a nuclear power plant had to be replaced with a new blade by cutting
the shroud to remove the cracked blade. This necessitated in situ welding of a new shroud piece with the existing shroud after
the blade replacement. The in situ welding of the shroud, a 12% Cr martensitic stainless steel with tempered martensite microstructure,
was carried out using gastungsten arc welding and 316L austenitic stainless steel filler metal followed by localized postweld
heat treatment at 873 K for 1 h using a specially designed electrical resistance-heating furnace. Mock-up trials were carried
out to ensure that sound welds could be made under the constraints present during the in situ repair welding operation. In
situ metallography of the repair weld after postweld heat treatment confirmed the adequate tempering of the martensitic structure
in the heat-affected zone. Metallurgical investigations carried out in the laboratory on a shroud test-piece that had been
welded using the same procedure as employed in the field confirmed the success of the in situ repair operation. The alternate
option available was replacing the cracked blade and the shroud piece to which it is riveted with a new one, reducing the
height of all the blades attached to the shroud by machining, riveting the blades with reduced height to the new shroud, and,
finally, dynamic balancing of the entire turbine after completion of the repair. This option is both time-consuming and expensive.
Hence, the successful completion of this repair welding resulted in enormous savings both in terms of reducing the downtime
of the plant and the cost of the repair. The turbine has been put back into service and has been operating satisfactorily
since December 2000. 相似文献
70.
Bahni Ray Dipankar Bandyopadhyay Ashutosh Sharma Sang Woo Joo Shizhi Qian Gautam Biswas 《Microfluidics and nanofluidics》2013,15(1):19-33
Spatiotemporal deformations of the free charged surface of a thin electrolyte film undergoing a coupled electrokinetic flow composed of an electroosmotic flow (EOF) on a charged solid substrate and an electrophoretic flow (EPF) at its free surface are explored through linear stability analysis and the long-wave nonlinear simulations. The nonlinear evolution equation for the deforming surface is derived by considering both the Maxwell’s stresses and the hydrodynamic stresses. The electric potential across the film is obtained from the Poisson–Boltzmann equation under the Debye–Hückel approximation. The simulations show that at the charged electrolyte–air interface, the applied electric field generates an EPF similar to that of a large charged particle. The EOF near the solid–electrolyte interface and the EPF at the electrolyte–air interface are in the same (or opposite) directions when the zeta potentials at the two interfaces are of the opposite (or same) signs. The linear and nonlinear analyses of the evolution equation predict the presence of travelling waves, which is strongly modulated by the applied electric field and the magnitude/sign of the interface zeta potentials. The time and length scales of the unstable modes reduce as the sign of zeta potential at the two interfaces is varied from being opposite to same and also with the increasing applied electric field. The increased destabilization is caused by a reverse EPF near the free surface when the interfaces bear the same sign of zeta potentials. Flow reversal by EPF at the free surface occurs at smaller zeta potential of the free surface when the film is thicker because of less influence of the EOF arising at the solid–electrolyte boundary. The amplitude of the surface waves is found to be smaller when the unstable waves travel at a faster speed. The films can undergo pseudo-dewetting when the free surface is almost stationary under the combined influences of EPF and EOF. The free surface instability of the coupled EOF and EPF has some interesting implications in the development of micro/nano fluidic devices involving a free surface. 相似文献