The main raw material utilized in wood adhesives comes from petrochemical extractives.However,due to the excessive dependence on petrochemical resources and the adverse impact on the ecosystem and human wellbeing,ther...The main raw material utilized in wood adhesives comes from petrochemical extractives.However,due to the excessive dependence on petrochemical resources and the adverse impact on the ecosystem and human wellbeing,there is an increasing trend to develop byproduct protein-based adhesives in the current global food safety context.In this research,flaxseed meal was subjected to pretreatment,and trimethylolpropane triglycidyl ether(TTE)and ethylenediamine(EN)were utilized as crosslinkers to establish a more compact adhesive layer and to prevent water intrusion.The pretreatment decreased the FM/UB viscosity by 60%compared to FM.The combination of CD analysis indicated that the Urea-NaOH pretreatment effectively stretched the flaxseed meal protein.According to Fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),and differential scanning calorimetry(DSC)were used to analyze the resulting adhesive’s reaction mechanism and thermal response.Furthermore,the physical properties of the adhesive were characterized using wet shear strength testing and SEM observation.Remarkably,the dry bond strength increased from 0.72 to 2.12 MPa,representing a 194.4%increase.The wet bonding strength of the adhesive was improved from 0.22 to 1.21 MPa,representing a 550%increase compared to the original flaxseed protein-based adhesive,which far exceeded the minimum requirement for plywood of Type II(≥0.7 MPa,by GB/T 9846-2015).This study demonstrated an eco-friendly and sustainable method for the development of protein adhesives as viable substitutes for petrochemical resins.展开更多
To analyze the effects of width and thickness of each composition element of mixed steel U-rib-stiffened plates on the welding residual stress distribution, the distribution of the U-rib and the plate residual stress ...To analyze the effects of width and thickness of each composition element of mixed steel U-rib-stiffened plates on the welding residual stress distribution, the distribution of the U-rib and the plate residual stress was calculated using a simplified calculation method. The method involved welding the mixed steel U-rib-stiffened plates for a structure with different sizes and different strength ratios of U-rib to plate. Based on a welding residual stress numerical simulation method validated by the blind hole method test, the distribution law of the mixed steel U-rib stiffened plate was studied. The results showed that the change of plate width has little impact on the welding residual stress and that the ratio of the thicknesses of the plate to U-rib stiffeners, the thickness of the plate, and the thickness of the U-rib has a great influence on the distribution of the welding residual stress. The thickness of plate and steel strength also greatly influenced the distribution width of the residual tensile stress. While analyzing the compression capacity of U-rib-stiffened plates, the simplified distribution of welding residual stress was used.展开更多
In order to decrease the evaporating rate of ammonia and increase the solubility of copper in the solution,ethylenediamine was added into the ammonia-ammonium chloride system to leach the copper-containing oxide ores....In order to decrease the evaporating rate of ammonia and increase the solubility of copper in the solution,ethylenediamine was added into the ammonia-ammonium chloride system to leach the copper-containing oxide ores.The thermodynamic model was constructed and the solubility of malachite Cu2(OH)2CO3 in the ammonia-ammonium chloride-ethylenediamine(En)-water system was calculated using the exponential computation method based on both mass balance and charge balance.It is found that the solubility of copper can be increased and the free ammonia concentration can be decreased by submitting partial ammonia with ethylenediamine.The lower free ammonia concentration in the solution is a guarantee to the lower evaporating rate of ammonia.The conditions of malachite Cu2(OH)2CO3 converting to atacamite Cu(OH)1.5Cl0.5 were also studied.A group of experiments were designed to validate the veracity of the results of the thermodynamic calculation.It is found that the thermodynamic model is reliable and it can guide the leaching process.展开更多
高超声速转捩研究飞行器(Hypersonic Transition Research Vehicle,HyTRV)是为研究高超声速复杂三维边界层转捩而设计的升力体标模,其外形更接近真实飞行器。为深入认识HyTRV边界层稳定性特征及转捩机制,验证数值模拟和理论分析结果,本...高超声速转捩研究飞行器(Hypersonic Transition Research Vehicle,HyTRV)是为研究高超声速复杂三维边界层转捩而设计的升力体标模,其外形更接近真实飞行器。为深入认识HyTRV边界层稳定性特征及转捩机制,验证数值模拟和理论分析结果,本文在马赫数6常规风洞中,采用红外热成像技术和高频压力传感器,获得了0°和2°攻角时HyTRV标模下表面(迎风面)的边界层转捩阵面及不稳定波的演化特征,并与一维稳定性分析结果进行了对比。研究结果表明:攻角为2°时,标模下表面的横流失稳区较0°攻角时范围缩小且位置后移,标模中心线处转捩早于两侧横流区。另外,横流区存在宽频的高频信号,信号幅值在转捩完成前达到饱和。该信号包含多频段扰动,多种扰动之间相互作用导致频谱变宽,最终促使边界层转捩变为湍流。展开更多
对比分析现行国家标准GB/T 31248—2014《电缆或光缆在受火条件下火焰蔓延热释放和产烟特性的试验方法》与欧盟标准EN 50399:2022 Common test methods for cables under fire conditions—Heat release and smoke production measureme...对比分析现行国家标准GB/T 31248—2014《电缆或光缆在受火条件下火焰蔓延热释放和产烟特性的试验方法》与欧盟标准EN 50399:2022 Common test methods for cables under fire conditions—Heat release and smoke production measurement on cables during flame spread test—Test apparatus,procedures,results主要技术差异,相比于国标,欧标关于试验装置的规定更加详细,同时增加了标准电缆试样校准、火焰形状校准、非圆形电缆数量及安装规定等技术内容。针对外径小于或等于5 mm的电缆,分析国标和欧标试样安装方式异同,并给出GB/T 31248—2014修订建议。展开更多
Friction stir processing(FSP) has emerged as a transformative solid-state technique for enhancing the mechanical performance and microstructural integrity of metallic materials,particularly in the context of additive ...Friction stir processing(FSP) has emerged as a transformative solid-state technique for enhancing the mechanical performance and microstructural integrity of metallic materials,particularly in the context of additive manufacturing(AM).This study demonstrates the effectiveness of FSP as a post-processing strategy for two distinct AM systems:wire arc additive manufacturing(WAAM) of low-carbon steel and selective laser melting(SLM) of Ti6Al4V alloy.In the case of WAAM fabricated steel,FSP significantly refined the coarse dendritic microstructure into ultrafine equiaxed grains,resulting in a 21 %-24 % increase in hardness and enhanced tensile properties at the overlapping regions.Similarly,for SLM fabricated Ti6Al4V,FSP eliminated the columnar prior-β grains and residual porosity,yielding a homogenous α+β structure with improved strengthductility balance and reduced anisotropy.These improvements were attributed to the dynamic recrystallization,conversion of low-angle to high-angle grain boundaries,and homogenization of phase constituents induced by FSP.Despite challenges such as tool wear and fixturing complexity,the study confirms that FSP can reliably bridge the performance gap in AM components by healing solidification defects,mitigating anisotropy,and tailoring the local microstructure.The findings position FSP as a versatile and scalable post-processing technique,crucial for advancing high-performance,application-ready components in aerospace,biomedical,and structural applications.展开更多
We present a computer-modeling framework for photovoltaic(PV)source emulation that preserves the exact single-diode physics while enabling iteration-free,real-time evaluation.We derive two closed-form explicit solvers...We present a computer-modeling framework for photovoltaic(PV)source emulation that preserves the exact single-diode physics while enabling iteration-free,real-time evaluation.We derive two closed-form explicit solvers based on the Lambert W function:a voltage-driven V-Lambert solver for high-fidelity I–V computation and a resistance-driven R-Lambert solver designed for seamless integration in a closed-loop PV emulator.Unlike Taylor-linearized explicit models,our proposed formulation retains the exponential nonlinearity of the PV equations.It employs a numerically stable analytical evaluation that eliminates the need for lookup tables and root-finding,all while maintaining limited computational costs and a small memory footprint.The R-Lambert model is integrated into a buck-converter emulator equipped with a discrete PI regulator,which generates current references directly from sensed operating points,thus supporting hardware-constrained implementation.Comprehensive numerical experiments conducted on six commercial modules from various technologies(mono,poly,and multicrystalline)demonstrate significant accuracy improvements under the IEC EN 50530 near-MPP criterion:the V-Lambert solver reduces the±10%Vmpp band error by up to 61 times compared to an explicit-model baseline.Dynamic simulations under varying irradiance,temperature,and load conditions achieve millisecond-scale settling with accurate trajectory tracking.Additionally,processor-in-the-loop experimental validation on an embedded microcontroller supports the simulation results.By unifying exact analytical modeling with embedded realization,this work advances computer modeling for PV emulation,MPPT benchmarking,and controller verification in integrated renewable energy systems.展开更多
文摘The main raw material utilized in wood adhesives comes from petrochemical extractives.However,due to the excessive dependence on petrochemical resources and the adverse impact on the ecosystem and human wellbeing,there is an increasing trend to develop byproduct protein-based adhesives in the current global food safety context.In this research,flaxseed meal was subjected to pretreatment,and trimethylolpropane triglycidyl ether(TTE)and ethylenediamine(EN)were utilized as crosslinkers to establish a more compact adhesive layer and to prevent water intrusion.The pretreatment decreased the FM/UB viscosity by 60%compared to FM.The combination of CD analysis indicated that the Urea-NaOH pretreatment effectively stretched the flaxseed meal protein.According to Fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),and differential scanning calorimetry(DSC)were used to analyze the resulting adhesive’s reaction mechanism and thermal response.Furthermore,the physical properties of the adhesive were characterized using wet shear strength testing and SEM observation.Remarkably,the dry bond strength increased from 0.72 to 2.12 MPa,representing a 194.4%increase.The wet bonding strength of the adhesive was improved from 0.22 to 1.21 MPa,representing a 550%increase compared to the original flaxseed protein-based adhesive,which far exceeded the minimum requirement for plywood of Type II(≥0.7 MPa,by GB/T 9846-2015).This study demonstrated an eco-friendly and sustainable method for the development of protein adhesives as viable substitutes for petrochemical resins.
文摘To analyze the effects of width and thickness of each composition element of mixed steel U-rib-stiffened plates on the welding residual stress distribution, the distribution of the U-rib and the plate residual stress was calculated using a simplified calculation method. The method involved welding the mixed steel U-rib-stiffened plates for a structure with different sizes and different strength ratios of U-rib to plate. Based on a welding residual stress numerical simulation method validated by the blind hole method test, the distribution law of the mixed steel U-rib stiffened plate was studied. The results showed that the change of plate width has little impact on the welding residual stress and that the ratio of the thicknesses of the plate to U-rib stiffeners, the thickness of the plate, and the thickness of the U-rib has a great influence on the distribution of the welding residual stress. The thickness of plate and steel strength also greatly influenced the distribution width of the residual tensile stress. While analyzing the compression capacity of U-rib-stiffened plates, the simplified distribution of welding residual stress was used.
基金Project(2007CB613604)supported by the National Basic Research Program of ChinaProject(50674104)supported by the National Natural Science Foundation of China
文摘In order to decrease the evaporating rate of ammonia and increase the solubility of copper in the solution,ethylenediamine was added into the ammonia-ammonium chloride system to leach the copper-containing oxide ores.The thermodynamic model was constructed and the solubility of malachite Cu2(OH)2CO3 in the ammonia-ammonium chloride-ethylenediamine(En)-water system was calculated using the exponential computation method based on both mass balance and charge balance.It is found that the solubility of copper can be increased and the free ammonia concentration can be decreased by submitting partial ammonia with ethylenediamine.The lower free ammonia concentration in the solution is a guarantee to the lower evaporating rate of ammonia.The conditions of malachite Cu2(OH)2CO3 converting to atacamite Cu(OH)1.5Cl0.5 were also studied.A group of experiments were designed to validate the veracity of the results of the thermodynamic calculation.It is found that the thermodynamic model is reliable and it can guide the leaching process.
文摘高超声速转捩研究飞行器(Hypersonic Transition Research Vehicle,HyTRV)是为研究高超声速复杂三维边界层转捩而设计的升力体标模,其外形更接近真实飞行器。为深入认识HyTRV边界层稳定性特征及转捩机制,验证数值模拟和理论分析结果,本文在马赫数6常规风洞中,采用红外热成像技术和高频压力传感器,获得了0°和2°攻角时HyTRV标模下表面(迎风面)的边界层转捩阵面及不稳定波的演化特征,并与一维稳定性分析结果进行了对比。研究结果表明:攻角为2°时,标模下表面的横流失稳区较0°攻角时范围缩小且位置后移,标模中心线处转捩早于两侧横流区。另外,横流区存在宽频的高频信号,信号幅值在转捩完成前达到饱和。该信号包含多频段扰动,多种扰动之间相互作用导致频谱变宽,最终促使边界层转捩变为湍流。
文摘对比分析现行国家标准GB/T 31248—2014《电缆或光缆在受火条件下火焰蔓延热释放和产烟特性的试验方法》与欧盟标准EN 50399:2022 Common test methods for cables under fire conditions—Heat release and smoke production measurement on cables during flame spread test—Test apparatus,procedures,results主要技术差异,相比于国标,欧标关于试验装置的规定更加详细,同时增加了标准电缆试样校准、火焰形状校准、非圆形电缆数量及安装规定等技术内容。针对外径小于或等于5 mm的电缆,分析国标和欧标试样安装方式异同,并给出GB/T 31248—2014修订建议。
基金funded by the National Natural Science Foundation of China(Grant No.52322508)the R&D Program of Beijing Municipal Education Commission(Grant No.KZ20231000519).
文摘Friction stir processing(FSP) has emerged as a transformative solid-state technique for enhancing the mechanical performance and microstructural integrity of metallic materials,particularly in the context of additive manufacturing(AM).This study demonstrates the effectiveness of FSP as a post-processing strategy for two distinct AM systems:wire arc additive manufacturing(WAAM) of low-carbon steel and selective laser melting(SLM) of Ti6Al4V alloy.In the case of WAAM fabricated steel,FSP significantly refined the coarse dendritic microstructure into ultrafine equiaxed grains,resulting in a 21 %-24 % increase in hardness and enhanced tensile properties at the overlapping regions.Similarly,for SLM fabricated Ti6Al4V,FSP eliminated the columnar prior-β grains and residual porosity,yielding a homogenous α+β structure with improved strengthductility balance and reduced anisotropy.These improvements were attributed to the dynamic recrystallization,conversion of low-angle to high-angle grain boundaries,and homogenization of phase constituents induced by FSP.Despite challenges such as tool wear and fixturing complexity,the study confirms that FSP can reliably bridge the performance gap in AM components by healing solidification defects,mitigating anisotropy,and tailoring the local microstructure.The findings position FSP as a versatile and scalable post-processing technique,crucial for advancing high-performance,application-ready components in aerospace,biomedical,and structural applications.
基金funded by Scientific Research Deanship at University of Ha’il-Saudi Arabia through project number(RG-24014).
文摘We present a computer-modeling framework for photovoltaic(PV)source emulation that preserves the exact single-diode physics while enabling iteration-free,real-time evaluation.We derive two closed-form explicit solvers based on the Lambert W function:a voltage-driven V-Lambert solver for high-fidelity I–V computation and a resistance-driven R-Lambert solver designed for seamless integration in a closed-loop PV emulator.Unlike Taylor-linearized explicit models,our proposed formulation retains the exponential nonlinearity of the PV equations.It employs a numerically stable analytical evaluation that eliminates the need for lookup tables and root-finding,all while maintaining limited computational costs and a small memory footprint.The R-Lambert model is integrated into a buck-converter emulator equipped with a discrete PI regulator,which generates current references directly from sensed operating points,thus supporting hardware-constrained implementation.Comprehensive numerical experiments conducted on six commercial modules from various technologies(mono,poly,and multicrystalline)demonstrate significant accuracy improvements under the IEC EN 50530 near-MPP criterion:the V-Lambert solver reduces the±10%Vmpp band error by up to 61 times compared to an explicit-model baseline.Dynamic simulations under varying irradiance,temperature,and load conditions achieve millisecond-scale settling with accurate trajectory tracking.Additionally,processor-in-the-loop experimental validation on an embedded microcontroller supports the simulation results.By unifying exact analytical modeling with embedded realization,this work advances computer modeling for PV emulation,MPPT benchmarking,and controller verification in integrated renewable energy systems.
