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Joining and machining of(ZrB2-SiC)and(Cf-SiC)based composites

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Defence Technology（防务技术） 2018年第5期14卷 385-395页

作者： R.v.Krishnarao G.Madhusudan reddy v.v.Bhanuprasad Defence Metallurgical Research Laboratory KanchanbaghHyderabad500058India

Filler materials of(ZrB_2-SiC-B_4C-YAG) composite were developed for gas tungsten arc welding(GTAW) of the ZrB_2-SiC and Cf-SiC based composites to themselves and to each other. Reaction with filler material,porosity and cracks were not observed at weld interfaces of all the joints. Penetration of filler material in to voids and pores existing in the Cf-SiC composites was observed. Average shear strength of 25.7 MPa was achieved for joints of Cf-SiC composites. By incorporation of Cf-SiC(CvD) ground short fibre reinforcement the(ZrB_2-SiC-B_4C-YAG) composite was machinable with tungsten carbide tool. The joint and machined composites were resistance to oxidation and thermal shock when exposed to the oxy-propane flame at 2300℃ for 300s. The combination of(ZrB_2-SiC-B_4C-YAG) and Cf-SiC based composites can be used for making parts like thermal protection system or nozzles for high temperature applications.

关键词： ZrB2-SiC Composite Sintering Machining Gas tungsten arc welding

Conditions for formation and trapping of the two-ion Coulomb cluster in the dissipative optical superlattice

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Chinese Physics B 2015年第6期24卷 305-313页

作者： I.v.Krasnov Institute of Computational Modeling Siberian DivisionRussian Academy of Sciences

Conditions have been studied under which a polychromatic optical superlattice can form and trap the Coulomb cluster of two strongly interacting ions. In our previous work （Krasnov I v and Kamenshchikov L P 2014 Opt. Comm. 312 192） this new all-optical method of obtaining and confining the Coulomb clusters was demonstrated by numerical simulations for special values of the optical superlattice parameters and in the case of Yb ions. In the present paper the conditions are explicitly formulated, under which the long-lived two-ion cluster in the superlattice cell is formed. The peculiarity of these conditions is the renormalization of the ion-ion Coulomb interaction. Notably, the renormalized Coulomb force is determined by the effective charge which depends on the light field parameters and can strongly differ from the ＂bare＂ ion charge. This result can be accounted for by the combined manifestation of the quantum fluctuations of optical forces, nonlinear dependence of these forces on the velocity, and non-Maxwellian （Tsallis type） velocity distribution of the ions in the optical superlattice. Explicit analytical formulas are also obtained for the parameters of the optical two-ion cluster.

关键词： optical trap ion trap rectified gradient force Coulomb clusters

Unravelling-based (auto)control of back-action in atomic Bose–Einstein condensate

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Frontiers of physics 2024年第4期19卷 287-295页

作者： v.A.Tomilin L.v.Il’ichov Institute of Automation and Electrometry SB RAS 630090 NovosibirskRussia

We present a novel feedback control method for quantum *** does not affect the controlled system ***,it controls the unravelling of the quantum channel of interaction between the system and its *** interaction can be represented as a history of *** their informational content is changed,their back-action on the system is also *** action is trigged by the events,thus granting the system the degree of control over its own *** efficiency of the proposed scheme is demonstrated on the example of two-mode atomic Bose-Einstein condensate,with one of its modes subject to phase-contrast imaging in a Mach–Zehnder *** histories of photocounts in the output channels of the interferometer are used for *** capabilities of state engineering are studied for different settings of the feedback loop and different numbers of events in the recorded histories.

关键词： quantum feedback control quantum measurements twomode Bose-Einstein condensates

Polarization patterns of light enable geolocalization in oceans

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Light(Science & Applications) 2023年第11期12卷 2264-2265页

作者： Lihong v.Wang Caltech Optical Imaging Laboratory Andrew and Peggy Cherng Department of Medical EngineeringDepartment of Electrical EngineeringCalifornia

The deep ocean,characterized by its immense depths and absence of global positioning system(GPS)functionality,presents considerable challenges for search and rescue *** by the geolocalization capabilities of migratory marine animals,Bai et *** a novel method for underwater geolocalization using the polarization patterns of light in the underwater *** a sextant using these underwater polarization patterns,the study determines geolocation in underwater *** prior skepticism,even in low-visibility waters,these patterns,learned through a deep neural network,provide geolocation accuracies of 55 km at 8m and 255 km at 50 *** pioneering approach offers implications for search and rescue and hints at navigation mechanisms in marine animals.

关键词： underwater enable visibility

Influence of the safety factor profile on the particle and heat transport in the Globus-M spherical tokamak

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Plasma Science and Technology 2019年第11期21卷 1-6页

作者： A YU TELNOvA G S KURSKIEv E O KISELEv N N BAKHAREv v K GUSEv N A KHROMOv S YU MEDvEDEv v B MIINAEv I v MIROSHNIKOv M I PATROv Yu v PETROv N v SAKHAROv A D SLADKOMEDOvA P B SHCHEGOLEv v v SOLOKHA v A TOKAREv S YU TOLSTYAKOv E A TUKHMENEvA Ioffe Institute Saint-Petersburg 194021Russia Keldysh Institute Russian Academy of SciencesMoscow 125047Russia NRC'Kurchatov Institute’ Moscow 123098Russia

The advanced tokamak scenario is a promising operation scenario for ITER and fusion neutron *** this scenario the minimum value of the safety factor in the center of the plasma exceeds *** the compact spherical tokamak Globus-M,the formation of such conditions is possible with neutral beam injection at the current ramp-up *** to the slower diffusion of current inside the plasma,a zone is formed with reduced heat and particle transport across the magnetic field,which affects the temperature and density profiles of the *** leads to the peaked density profile formation and improvement of the energy confinement *** achieve a high fraction of the bootstrap current,it is necessary to increase the plasma *** the same time,the maximum allowable pressure is limited to the normalized beta limit.

关键词： advanced tokamak mode transport analysis internal transport barriers

Effect of graphene and its derivatives on thermo-mechanical properties of phase change materials and its applications:a comprehensive review

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Frontiers in Energy 2022年第2期16卷 150-186页

作者： Sumit NAGAR Kamal SHARMA A.K.PANDEY v.v.TYAGI Department of Mechanical Engineering GLA UniversityMathura(U.P)-281406India Research Center for Nano-Materials and Energy Technology(RCNMET) School of Engineering and TechnologySunway University47500 Selangor Darul EhsanMalaysia School of Energy Management Shri Mata Vaishno Devi UniversityKatra 182320India

Phase change materials(PCMs)play a leading role in overcoming the growing need of advanced thermal management for the storage and release of thermal energy which is to be used for different solar ***,the effectiveness of PCMs is greatly affected by their poor thermal ***,in the present review the progress made in deploying the graphene(Gr)in PCMs in the last decade for providing the solution to the aforementioned inadequacy is presented and discussed in *** and its derivatives((Gr oxide(GO),Gr aerogel(GA)and Gr nanoplatelets(GNPs))based PCMs can improve the thermal conductivity and shape stability,which may be attributed to the extra ordinary thermo-physical properties of ***,it is expected from this review that the advantages and disadvantages of using Gr nanoparticles provide a deep insight and help the researchers in finding out the exact basic properties and finally the applications of Gr can be *** this work,Gr and its derivatives based PCMs was characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction spectroscopy(Xrd),and scanning electron microscopy(SEM)by which crystal structure was known,phase was identified along with the knowledge of surface structure *** increase in the mass fraction(%)of the filler(Gr and its derivatives)led to even better thermo-physical properties and thermal *** thermal characterization was also done by differential scanning calorimetry(DSC),thermo gravimetric analysis(TGA)and thermal conductivity *** enthalpy of freezing and melting showed that Gr and its derivatives based PCMs had a very high energy storage capability as reflected in its various applications.

关键词： phase change materials(PCMs) graphene thermal conductivity characterization

MgCo2-D2 and MgCoNi-D2 systems synthesized at high pressures and interaction mechanism during the HDDR processing

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Progress in Natural Science:Materials International 2017年第1期27卷 74-80页

作者： Chubin Wan v.E.Antonov R.v.Denys v.I.Kulakov v.A.Yartys University of Science and Technology Beijing Institute for Energy Technology Institute of Solid State Physics Russian Academy of Sciences HYSTORSYS AS Norwegian University of Science and Technology

MgCo2and MgNiCo crystallize with hexagonal Laves type intermetallic structures of the C14 type and do not form hydrides at ambient hydrogen pressures. However, applying high hydrogen pressures in the GPa range forces the hydrogen absorption and leads to the formation of multi-phase compositions, which contain approximately 2.5 atoms H per formula unit of MgCo2or MgNiCo and remain thermally stable under normal *** hydrogenation of MgCo2resulted in its decomposition to a ternary Mg2CoD5deuteride and metallic cobalt. Phase-structural transformations accompanying the vacuum desorption of deuterium in the temperature range of 27–500 °C were studied using in situ neutron powder diffraction. The investigation showed a complete recovery of the initial MgCo2intermetallic via a Hydrogenation-Disproportionation-Desorption-Recombination process. At 300°C, the Mg2CoD5deuteride first decomposed to elementary Mg and hexagonal Co. At 400°C, a MgCo phase was formed by interaction between Mg and Co. At the highest processing temperature of 500°C, a solid-state interaction of MgCo and Co resulted in the recovery of the initial *** interaction of MgNiCo with deuterium under the synthesis conditions of 2.8 GPa and 200 °C proceeded in a more complex way. A very stable ternary deuteride MgNi2D3was leached away while Co was separated in the form of Mg2CoD5and the remaining nickel formed a solid solution with Co with the approximate composition *** thermal desorption of deuterium from MgCo2D2.5and from MgNiCoD2.5has been studied by Thermal Desorption Spectroscopy with deuterium released into a closed volume. The observed effects nicely correlate with changes in the phase structural composition of the hydrides ***2is a new example of the hydrogen storage alloy, in which a successful HDDR processing results in the reversible formation of the initial intermetallic at much lower temperatures than in the equilibrium phase diagram of the Mg-Co system.

关键词： Intermetallics Hydrogen storage materials Neutron powder diffraction High pressure synthesis Phase-structural transformations Magnesium Cobalt Nickel

Unveiling the atomic-scale transition between light harvesting and photoprotective states in plant photosynthesis

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Science China Chemistry 2024年第5期67卷 1375-1377页

作者： Alexander v.Ruban School of Biological and Behavioural Sciences Queen Mary University of LondonLondon E14NSUK

Non-photochemical chlorophyll fluorescence quenching(NPQ) stands as a cornerstone in the realm of photosynthesis research, attracting generations of dedicated scientists in their quest to unravel its mysteries. This mechanism, crucial for safeguarding photosynthesis, plays a pivotal role in regulating light harvesting, particularly in oxygenic photosynthesis where the oxygen-evolving photosystem II (PSII)is susceptible to photodamage [1].

关键词： harvesting protective attracting

Optimizing the Pulsed Current Gas Tungsten Arc Welding Parameters

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Journal of Materials Science & Technology 2006年第6期22卷 821-825页

作者： M.Balasubramanian v.Jayabalan v. Balasubramanian Department of Production Engineering Sathyabama Institute of Science and TechnologyIndia Department of Manufacturing Engineering Anna UniversityIndia Department of Manufacturing Engineering Annamalai UniversityIndia

The selection of process parameter in the gas tungsten arc （GTA） welding of titanium alloy was presented for obtaining optimum grain size and hardness. Titanium alloy （Ti-6Al-4v） is one of the most important non-ferrous metals which offers great potential application in aerospace, biomedical and chemical industries, because of its low density （4.5 g/cm^3）, excellent corrosion resistance, high strength, attractive fracture behaviour and high melting point （1678℃）. The preferred welding process for titanium alloy is frequent GTA welding due to its comparatively easier applicability and better economy. In the case of single pass （GTA） welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one needs to carefully balance various pulse current parameters to reach an optimum combination. Four factors, five level, central composite, rotatable design matrix were used to optimize the required number of experimental conditions. Mathematical models were developed to predict the fusion zone grain size using analysis of variance （ANOvA） and regression analysis. The developed models were optimized using the traditional Hooke and Jeeve＇s algorithm. Experimental results were provided to illustrate the proposed approach.

关键词： Pulsed current Gas tungsten arc welding Titanium alloy Design of experiments ANOvA, Hooke and Jeeve's algorithm Grain size Hardness