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Influence of processing parameters on the microstructure and tensile property of 85 W-15Ni produced by laser direct deposition
摘要： The plate-like shape 85W-15Ni parts were produced by laser direct deposition technology with different processing parameters (laser power and scanning speed). The influence of processing parameters and their corresponding laser energy density on the microstructural characterization, phase composition and tensile property of 85W-15Ni samples was investigated. The results show that the relative density of samples increased with the laser energy density and the densification trend started to slow as the laser energy density reached 380-400 J/mm3, though the highest density value was obtained with laser energy of 425 J/mm3. With the increase of laser energy density, more disorder and fine W dendrites existed at the bonding region between deposition layers and more W-W grain boundaries formed at the central region of the layer. The 85W-15Ni samples produced with different processing parameters consisted of W and γ-Ni phase. To improve the tensile property, it is necessary to increase the laser energy density to obtain denser structure and reduce the residual pores or gaps. However, the excessive laser energy density resulted in the formation of more W-W grain boundaries that were detrimental to the tensile property. The best tensile properties were obtained at the laser energy density of 395 J/mm3.
关键词： 85W-15Ni,Laser direct deposition,Tensile property,Laser energy density,microstructural characterization
更新于2025-11-28 14:24:20
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Tuning Molecular Solar Thermal properties by modification of a promising norbornadiene photoswitch
摘要： Carefully targeted modifications to the norbornadiene-quadricyclane couple should give molecules with great potential for solar energy storage. Here we report the synthesis of derivatives of a well-studied compound, 2-cyano-3-anisyl norbornadiene (NBD5). The conjugation was extended by conversion of the nitrile into acrylonitrile and acrylate derivatives over two steps. Despite red-shifting the absorbance properties, the metastable quadricyclanes exhibited extremely short lifetimes. Meanwhile, treatment of NBD5 with acetyl halides in the presence of aluminum trihalides led to the formation of 7-acetyl norbornenes through a Meerwein-Wagner rearrangement. Subsequent transformations made it possible to synthesise norbornadienes with varying degrees of steric bulk at the 7-position of the molecular scaffold. It was found that the bulkier this group was, the more stable the quadricyclane form. This reaction sequence allows for the synthesis of norbornadiene derivatives which are more suited to molecular solar thermal applications in domestic heating despite providing a slightly lower energy density.
关键词： Meerwein-Wagner rearrangement,conjugation,strained molecules,photochromism,energy density
更新于2025-11-19 16:56:35
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[IEEE SoutheastCon 2018 - St. Petersburg, FL (2018.4.19-2018.4.22)] SoutheastCon 2018 - Evaluation of Reference Generation Algorithms for Dispatching Solar PV Power
摘要： This paper aims to develop a low-cost energy storage system by evaluating reference generation algorithms for dispatching solar power for 1 MW photovoltaic (PV) arrays. Based on battery state of charge (SOC), rule-based algorithms are developed to adjust the grid reference power for each one-hour dispatching period. In this paper, several rule-based algorithms are used to control the SOC of the battery that plays a significant role to design cost-effective energy storage system. The price comparison is made between two kinds of energy storage system (i) Battery only (ii) Battery+ Supercapacitor (SC), where a low pass filter is used to allocate power between battery and SC. The most economical energy storage system is developed through extensive simulations in MATLAB/Simulink environment. The results show that the hybrid energy storage system (HESS), combination of battery and SC, outperforms a battery-only operation.
关键词： intermittent solar energy,high power density,depth of discharge (DOD),state of charge (SOC),high energy density,hourly dispatching
更新于2025-09-23 15:21:01
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[IEEE SoutheastCon 2018 - St. Petersburg, FL, USA (2018.4.19-2018.4.22)] SoutheastCon 2018 - Evaluation of Reference Generation Algorithms for Dispatching Solar PV Power
摘要： This paper aims to develop a low-cost energy storage system by evaluating reference generation algorithms for dispatching solar power for 1 MW photovoltaic (PV) arrays. Based on battery state of charge (SOC), rule-based algorithms are developed to adjust the grid reference power for each one-hour dispatching period. In this paper, several rule-based algorithms are used to control the SOC of the battery that plays a significant role to design cost-effective energy storage system. The price comparison is made between two kinds of energy storage system (i) Battery only (ii) Battery+ Supercapacitor (SC), where a low pass filter is used to allocate power between battery and SC. The most economical energy storage system is developed through extensive simulations in MATLAB/Simulink environment. The results show that the hybrid energy storage system (HESS), combination of battery and SC, outperforms a battery-only operation.
关键词： intermittent solar energy,high power density,depth of discharge (DOD),state of charge (SOC),high energy density,hourly dispatching
更新于2025-09-23 15:21:01
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Robust flower-like ZnO assembled ?2-PVDF/BT hybrid nanocomposite: Excellent energy harvester
摘要： Need of renewable green energy sources due to low cost synthesis, mechanically strong, high energy storage capacity with improved dielectric performance have been receiving much attention. Present work render the ZnO particle and flower-like morphology assemble semicrystalline β phase PVDF/BT nanocomposite, successfully synthesized by spin coating method and characterized by XRD, SEM, EDS and FTIR techniques. Also the energy storage density of composite with modified structure is largely increased with value 0.056 Jcm-3 at 6 MV/m which is 66% higher than virgin β-PVDF and 82% piezoelectric energy harvesting efficiency. Maximum dielectric constant is 1774 at 1 Hz for PVDF-BaTiO3-ZnOf [P-BT-ZnOf] nanocomposite film and maximum breakdown strength of 43 kVcm-1. Electrochemical study reveals that P-BT-ZnOf nanocomposite film manifest better potential material. In terms of mechanical performance, P-BT-ZnOf nanocomposite shows maximum Young modulus of 204 MPa, tensile strength of 28.7 MPa and 23.1% elongation to break. These results provide promising capability to enhance the performance of composites for energy storage application, transducers, sensors, capacitors etc.
关键词： Energy density,Tensile strength,Dielectric constant,Nanocomposites,Breakdown strength
更新于2025-09-23 15:21:01
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A comprehensive approach for characterisation of the deposited energy density during laser-matter interaction in liquids and solids
摘要： We present a novel approach for characterisation of ultrafast laser-matter interaction processes both in solids and liquids under extreme conditions of microplasma generation. By combination of three-dimensional propagation imaging, absorption measurements, shadowgraphy and photoacoustic imaging we can restore plasma electron density distribution, laser pulse fluence profile and the value of deposited energy density inside the bulk of the material and characterise the regime of the laser pulse propagation. The developped concept is important to understand the physics of ultrafast laser-matter interaction with strong implications for precision control of laser micromachining, bioprocessing and biotreatment.
关键词： three-dimensional propagation imaging,photoacoustics,femtosecond filamentation,laser-matter interaction,deposited energy density,shadowgraphy
更新于2025-09-23 15:21:01
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Demonstration of Scale-Invariant Rayleigh-Taylor Instability Growth in Laser-Driven Cylindrical Implosion Experiments
摘要： Rayleigh-Taylor instability growth is shown to be hydrodynamically scale invariant in convergent cylindrical implosions for targets that varied in radial dimension and implosion timescale by a factor of 3. The targets were driven directly by laser irradiation providing a short impulse, and instability growth at an embedded aluminum interface occurs as it converges radially inward by a factor of 2.25 and decelerates on a central foam core. Late-time growth factors of 14 are observed for a single-mode m ? 20 azimuthal perturbation at both scales, despite the differences in laser drive conditions between the experimental facilities, consistent with predictions from radiation-hydrodynamics simulations. This platform enables detailed investigations into the limits of hydrodynamic scaling in high-energy-density systems.
关键词： high-energy-density physics,hydrodynamic scaling,laser-driven implosions,Rayleigh-Taylor instability
更新于2025-09-23 15:21:01
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Molecular dynamics simulation of coalescence kinetics and neck growth in laser additive manufacturing of aluminum alloy nanoparticles
摘要： Laser additive manufacturing emerged as an advanced manufacturing process to fabricate components in a layered fashion by fusing the powder particles. This process is multifaceted and pivotal to understand the underlying physics of the coalescence of powder particles during the process, which impacts the structural and mechanical properties of the build component. In this study, a classical molecular dynamics (MD) model is developed for the coalescence of pre-alloyed aluminum alloy (AlSi10Mg) particles during the laser additive manufacturing process. The model is employed to investigate the neck growth and coalescence kinetics of different pairs of particle size with changing the laser energy density from 7 to 17 J/mm2. The simulation results reveal that the unevenly sized particles undergo complete coalescence as compared with even-sized particles, and the neck growth rate of AlSi10Mg particles increases with an increase in laser energy density. Based on the present investigation, it is established that the coalescence kinetics of the AlSi10Mg nanoparticles are governed by the surface and volume diffusion and the surface energy reduction during the joining of particles. This analysis will act as a guideline to design process parameters and quality control for the printing of new components.
关键词： Molecular dynamics,Laser additive manufacturing,Coalescence,Laser energy density,Powder bed fusion
更新于2025-09-23 15:21:01
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Influence of Laser Energy Density on Acquisition and Wear Resistance of Bionic Semisolid Unit of 40Cr Steel
摘要： 40Cr steel is one of the most common materials for manufacturing brake camshaft of trailer. The brake camshaft is subjected to extreme wear during its service life. In order to enhance wear resistance, medium frequency induction hardening (MFIH) treatment is usually conducted on the surface of brake camshaft. However, conventional MFIH technique requires heating of the entire surface, which has the drawbacks of more power consumption, high production cost and easy deformation. Therefore, inspired by the bionic theory, a process named as ‘‘laser bionic semisolid treatment’’ method accompanied by favorable surface roughness and minimum distortion has been proposed herein as an alternative to MFIH method. By this means, bionic units with different surface roughness, sizes microstructure and hardness were manufactured on the surface of 40Cr steel. Then, the wear resistance of 40Cr steel with various laser energy densities was experimentally investigated. The results demonstrated that when the laser energy density was 18:00t3 (cid:2)3 J/ mm2, the bionic semisolid unit was obtained with the arithmetic mean surface roughness Ra of 1046.81 nm. Moreover, in the wear resistance of 40Cr steel due to the microstructure and higher hardness compared with the untreated sample, and its weight loss ratio was decreased by 71.90%. The mechanism of wear resistance enhancement was also discussed.
关键词： bionic semisolid unit,40Cr steel,wear resistance,laser energy density,surface roughness
更新于2025-09-23 15:21:01
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Local plasma parameter measurements in colliding laser-produced plasmas for studying magnetic reconnection
摘要： We have implemented laser Thomson scattering for local plasma measurement of electron and ion temperatures, electron density, flow velocity, and charge state. The electron density increases by two times in the interaction of two plasma flows, indicating collisionless interaction. The density and velocity show fluctuations only at ns, and the density suddenly decreases, indicating the plasma ejection from the interaction region, which can be explained by a magnetic reconnection. The electron temperature in the double-flow is larger than that in the single flow. This may be explained by the energy transfer from the plasma kinetic energy to thermal energy. The ion temperature is much larger than electron temperature in the double-flow, and this may be explained by collisional effects between two plasmas, and/or possibly interpreted as a thermalization due to magnetic re-connection.
关键词： High energy density plasmas,Magnetic reconnection,Laser Thomson scattering
更新于2025-09-23 15:21:01