Variational Mode Decomposition-Informed Empirical Wavelet Transform for Electric Vibrator Noise Analysis

Electric vibrators find wide applications in reliability testing, waveform generation, and vibration simulation, making their noise characteristics a topic of significant interest. While Variational Mode Decomposition (VMD) and Empirical Wavelet Transform (EWT) offer valuable support for studying signal components, they also present certain limitations. This article integrates the strengths of both methods and proposes an enhanced approach that integrates VMD into the frequency band division principle of EWT. Initially, the method decomposes the signal using VMD, determining the mode count based on residuals, and subsequently employs EWT decomposition based on this information. This addresses mode aliasing issues in the original method while capitalizing on VMD’s adaptability. Feasibility was confirmed through simulation signals and ultimately applied to noise signals from vibrators. Experimental results demonstrate that the improved method not only resolves EWT frequency band division challenges but also effectively decomposes signal components compared to the VMD method.

Fabrication of Ceramic-Polymer Piezo-Composites with Triply Periodic Minimal Interfaces via Digital Light Processing

The geometry of the phase interface in co-continuous piezoelectric composites is critical in improving their piezo-electric properties.However,conventional co-continuous piezoelectric composites are mostly simple structures such as wood stacks or honeycombs,which are prone to stress concentrations at the joints,thus reducing the fatigue service performance and force-electric conversion efficiency of piezoelectric composites.Such simple structures limit further improvements in the overall performance of co-continuous piezoelectric composites.In this study,based on the digital light processing 3D printing method,we investigated the influence of three dif-ferent structures-the gyroid,diamond,and woodpile interfaces-on the piezoelectric and mechanical properties of co-continuous ceramic/polymer piezoelectric composites.These findings demonstrate that the gyroid and di-amond interfaces outperformed the ceramic skeleton of the woodpile interface in terms of both mechanical and electrical properties.When the ceramic volume percentage was 50%,the piezo-composite of the gyroid surface exhibited the greatest hydrostatic figure of merit(HFOM),reaching 4.23×10^(−12) Pa^(−1),and its piezoelectric coeffi-cient(d_(33))and relative dielectric constant(εr)reached 115 pC/N and 748,respectively.The research results lay the foundation for the application of co-continuous piezoelectric composites in underwater communication and detection.

The chemokine CCL17 is a novel therapeutic target for cardiovascular aging

Dear Editor,Aging results in higher susceptibility to age-related disease,especially cardiovascular disease,which has become a public health priority.1,2 Recent studies have progressively unraveled the critical role of vasculature as a gatekeeper of life-span and health-span.3 In this light,vascular rejuvenation is geroprotective.The circulating proteomic signature is tightly related to aging and aging-induced vascular diseases,4 but drugs targeting circulating proteins are not available.

Additive Manufacturing(AM)of Advanced Ceramics:From Materials,Structural Designing,AM Technologies,to Performance of Printed Components

Advanced ceramic materials have been widely used in a range of high-end technical fields due to their high mechanical performance,chemical stability,and impressive acoustic,optical,electrical,magnetic,and thermal properties.With the continuous improvement of the current level of science and technology,especially in cutting-edge application scenarios,the structural and functional requirements of advanced ce-ramic parts are becoming increasingly higher.

Additive manufacturing of metals:Microstructure evolution and multistage control

As a revolutionary industrial technology,additive manufacturing creates objects by adding materials layer by layer and hence can fabricate customized components with an unprecedented degree of freedom.For metallic materials,unique hierarchical microstructures are constructed during additive manufacturing,which endow them with numerous excellent properties.To take full advantage of additive manufacturing,an in-depth understanding of the microstructure evolution mechanism is required.To this end,this review explores the fundamental procedures of additive manufacturing,that is,the formation and binding of melt pools.A comprehensive processing map is proposed that integrates melt pool energy-and geometry-related process parameters together.Based on it,additively manufactured microstructures are developed during and after the solidification of constituent melt pool.The solidification structures are composed of primary columnar grains and fine secondary phases that form along the grain boundaries.The post-solidification structures include submicron scale dislocation cells stemming from internal residual stress and nanoscale precipitates induced by intrinsic heat treatment during cyclic heating of adjacent melt pool.Based on solidification and dislocation theories,the formation mechanisms of the multistage microstructures are thoroughly analyzed,and accordingly,multistage control methods are proposed.In addition,the underlying atomic scale structural features are briefly discussed.Furthermore,microstructure design for additive manufacturing through adjustment of process parameters and alloy composition is addressed to fulfill the great potential of the technique.This review not only builds a solid microstructural framework for metallic materials produced by additive manufacturing but also provides a promising guideline to adjust their mechanical properties.

Photopolymerization-based additive manufacturing of ceramics:A systematic review

Conversion of inorganic-organic frameworks (ceramic precursors and ceramic-polymer mixtures) into solid mass ceramic structures based on photopolymerization process is currently receiving plentiful attention in the field of additive manufacturing (3D printing).Various techniques(e.g.,stereolithography,digital light processing,and two-photon polymerization) that are compatible with this strategy have so far been widely investigated.This is due to their cost-viability,flexibility,and ability to design and manufacture complex geometric structures.Different platforms related to these techniques have been developed too,in order to meet up with modem technology demand.Most relevant to this review are the challenges faced by the researchers in using these 3D printing techniques for the fabrication of ceramic structures.These challenges often range from shape shrinkage,mass loss,poor densification,cracking,weak mechanical performance to undesirable surface roughness of the final ceramic structures.This is due to the brittle nature of ceramic materials.Based on the summary and discussion on the current progress of material-technique correlation available,here we show the significance of material composition and printing processes in addressing these challenges.The use of appropriate solid loading,solvent,and preceramic polymers in forming slurries is suggested as steps in the right direction.Techniques are indicated as another factor playing vital roles and their selection and development are suggested as plausible ways to remove these barriers.

Additive manufacturing of thin electrolyte layers via inkjet printing of highly-stable ceramic inks

Inkjet printing is a promising alternative for the fabrication of thin film components for solid oxide fuel cells(SOFCs) due to its contactless, mask free, and controllable printing process. In order to obtain satisfying electrolyte thin layer structures in anode-supported SOFCs, the preparation of suitable electrolyte ceramic inks is a key. At present, such a kind of 8 mol% Y_(2)O_(3)-stabilized ZrO_(2)(8 YSZ) electrolyte ceramic ink with long-term stability and high solid loading(> 15 wt%) seems rare for precise inkjet printing, and a number of characterization and performance aspects of the inks, such as homogeneity, viscosity, and printability, should be studied. In this study, 8 YSZ ceramic inks of varied compositions were developed for inkjet printing of SOFC ceramic electrolyte layers. The dispersing effect of two types of dispersants, i.e., polyacrylic acid ammonium(PAANH4) and polyacrylic acid(PAA), were compared. The results show that ultrasonic dispersion treatment can help effectively disperse the ceramic particles in the inks. PAANH4 has a better dispersion effect for the inks developed in this study. The inks show excellent printable performance in the actual printing process. The stability of the ink can be maintained for a storage period of over 30 days with the help of initial ultrasonic dispersion. Finally, micron-size thin 8 YSZ electrolyte films were successfully fabricated through inkjet printing and sintering, based on the as-developed high solid loading 8 YSZ inks(20 wt%). The films show fully dense and intact structural morphology and smooth interfacial bonding, offering an improved structural quality of electrolyte for enhanced SOFC performance.

Novel 3D grid porous Li_(4)Ti_(5)O_(12) thick electrodes fabricated by 3D printing for high performance lithium-ion batteries

Three-dimensional(3D)grid porous electrodes introduce vertically aligned pores as a convenient path for the transport of lithium-ions(Li-ions),thereby reducing the total transport distance of Li-ions and improving the reaction kinetics.Although there have been other studies focusing on 3D electrodes fabricated by 3D printing,there still exists a gap between electrode design and their electrochemical performance.In this study,we try to bridge this gap through a comprehensive investigation on the effects of various electrode parameters including the electrode porosity,active material particle diameter,electrode electronic conductivity,electrode thickness,line width,and pore size on the electrochemical performance.Both numerical simulations and experimental investigations are conducted to systematically examine these effects.3D grid porous Li_(4)Ti_(5)O_(12)(LTO)thick electrodes are fabricated by low temperature direct writing technology and the electrodes with the thickness of 1085μm and areal mass loading of 39.44 mg·cm^(−2) are obtained.The electrodes display impressive electrochemical performance with the areal capacity of 5.88 mAh·cm^(−2)@1.0 C,areal energy density of 28.95 J·cm^(−2)@1.0 C,and areal power density of 8.04 mW·cm^(−2)@1.0 C.This study can provide design guidelines for obtaining 3D grid porous electrodes with superior electrochemical performance.

Advances in 3D printing of magnetic materials:Fabrication,properties,and their applications

Magnetic materials are of increasing importance for many essential applications due to their unique magnetic properties.However,due to the limited fabrication ability,magnetic materials are restricted by simple geometric shapes.Three-dimensional(3D)printing is a highly versatile technique that can be utilized for constructing magnetic materials.The shape flexibility of magnets unleashes opportunities for magnetic composites with reducing post-manufacturing costs,motivating the review on 3D printing of magnetic materials.This paper focuses on recent achievements of magnetic materials using 3D printing technologies,followed by the characterization of their magnetic properties,which are further enhanced by modification.Interestingly,the corresponding properties depend on the intrinsic nature of starting materials,3D printing processing parameters,and the optimized structural design.More emphasis is placed on the functional applications of 3D-printed magnetic materials in different fields.Lastly,the current challenges and future opportunities are also addressed.

Enhanced cathodic activity by tantalum inclusion at B-site of La_(0.6)Sr_(0.4)Co_(0.4)Fe_(0.6)O_(3)based on structural property tailored via camphor-assisted solid-state reaction

Lanthanum strontium cobalt ferrite(LSCF)is an appreciable cathode material for solid oxide fuel cells(SOFCs),and it has been widely investigated,owing to its excellent thermal and chemical stability.However,its poor oxygen reduction reaction(ORR)activity,particularly at a temperature of≤800℃,causes setbacks in achieving a peak power density of>1.0 W·cm^(-2),limiting its application in the commercialization of SOFCs.To improve the ORR of LSCF,doping strategies have been found useful.Herein,the porous tantalum-doped LSCF materials(La_(0.6)Sr_(0.4)Co_(0.4)Fe_(0.5)7Ta_(0.03)O_(3)(LSCFT-0),La_(0.6)Sr_(0.4)Co_(0.4)Fe_(0.5)4Ta0.06O_(3),and La_(0.6)Sr_(0.4)Co_(0.4)Fe_(0.5)Ta0.1O_(3))are prepared via camphor-assisted solid-state reaction(CSSR).The LSCFT-0 material exhibits promising ORR with area-specific resistance(ASR)of 1.260,_(0.5)80,0.260,0.100,and 0.06Ω·cm^(2)at 600,650,700,750,and 800℃,respectively.The performance is about 2 times higher than that of undoped La_(0.6)Sr_(0.4)Co_(0.4)Fe_(0.6)O_(3)with the ASR of 2.515,1.191,_(0.5)96,0.320,and 0.181Ω·cm^(2)from the lowest to the highest temperature.Through material characterization,it was found that the incorporated Ta occupied the B-site of the material,leading to the enhancement of the ORR activity.With the use of LSCFT-0 as the cathode material for anode-supported single-cell,the power density of>1.0 W·cm^(-2)was obtained at a temperature<800℃.The results indicate that the CSSR-derived LSCFT is a promising cathode material for SOFCs.

Design and 3D Printing of Interdigitated Electrode Structures for High-performance Full Lithium-ion Battery

The tradeoff between energy and power densities is a critical challenge for commercial tape-cast lithium-ion batteries(LIBs).In this study,three-dimensional(3D)LIBs with interdigitated electrode structures are designed and fabricated via 3D printing to overcome this tradeoff.The evolution of battery design from tape-cast thin planar electrodes to interdigitated 3D electrodes is discussed.Numerical simulations based on COMSOL Multiphysics are performed to elucidate the advantages of interdigitated battery design.Interdigitated LIBs composed of comb-like 3D high-voltage LiCoO2(HV-LCO)cathodes and comb-like 3D natural graphite anodes are fabricated via 3D printing.Additionally,printable HV-LCO inks with appropriate rheological properties are developed for 3D printing.HV-LCO half-cells with Li foil as the counter electrode and an interdigitated full battery with NG anodes as the counter electrode are assembled to test the electrochemical performance.The results show that interdigitated full batteries fabricated via 3D printing offer high specific capacities and stable cycling performance.Full batteries with an electrode thickness of 882µm can achieve a high areal capacity of 5.88 mAh·cm−2@0.1 C,an areal energy density of 41.4 J·cm−2,and an areal power density of 41.0 mW·cm−2@1.0 C,which are approximately 10 times the values afforded by conventional tape-cast thin batteries.