Small Sample Gear Fault Diagnosis Method Based on Transfer Learning

Aiming at the problems of lack of fault diagnosis samples and low model generalization ability of cross-working gear based on deep transfer learning, a fault diagnosis method based on improved deep residual network and transfer learning was proposed. Firstly, one-dimensional signal is transformed into two-dimensional time-frequency image by continuous wavelet transform. Then, a deep learning model based on ResNet50 is constructed. Attention mechanism is introduced into the model to make the model pay more attention to the useful features for the current task. The network parameters trained by ResNet50 network on ImageNet dataset were used to initialize the model and applied to the fault diagnosis field. Finally, to solve the problem of gear fault diagnosis under different working conditions, a small sample training set is proposed for fault diagnosis. The method is applied to gearbox fault diagnosis, and the results show that: The proposed deep model achieves 99.7% accuracy of gear fault diagnosis, which is better than the four models such as VGG19 and MobileNetV2. In the cross-working condition fault diagnosis, only 20% target dataset is used as the training set, and the proposed method achieves 93.5% accuracy.

Research and Development of Electro‑hydraulic Control Valves Oriented to Industry 4.0:A Review

Electro-hydraulic control valves are key hydraulic components for industrial applications and aerospace,which controls electro-hydraulic motion.With the development of automation,digital technology,and communication technology,electro-hydraulic control valves are becoming more digital,integrated,and intelligent in order to meet the requirements of Industry 4.0.This paper reviews the state of the art development for electro-hydraulic control valves and their related technologies.This review paper considers three aspects of state acquisition through sensors or indirect acquisition technologies,control strategies along with digital controllers and novel valves,and online maintenance through data interaction and fault diagnosis.The main features and development trends of electro-hydraulic control valves oriented to Industry 4.0 are discussed.

Air-Stable Ultrabright Inverted Organic Light-Emitting Devices with Metal Ion-Chelated Polymer Injection Layer

Here,this work presents an air-stable ultrabright inverted organic lightemitting device(OLED)by using zinc ionchelated polyethylenimine(PEI)as electron injection layer.The zinc chelation is demonstrated to increase the conductivity of the PEI by three orders of magnitude and passivate the polar amine groups.With these physicochemical properties,the inverted OLED shows a record-high external quantum efficiency of 10.0% at a high brightness of 45,610 cd m^(-2) and can deliver a maximum brightness of 121,865 cd m^(-2).Besides,the inverted OLED is also demonstrated to possess an excellent air stability(humidity,35%)with a half-brightness operating time of 541 h@1000 cd m^(-2) without any protection nor encapsulation.

Ligand enabled none-oxidative decarbonylation of aliphatic aldehydes

Decarbonylation of aldehydes is a basic organic transformation, which has been developed for more than six-decade. However, as comparing to well-studied aromatic aldehydes, fewer examples for catalytic decarbonylation of aliphatic aldehydes were reported, mainly on simple or special substrates.For α-bulky or highly functionalized ones, stoichiometric Rh(I) were usually required for decent yields.Herein, we present a rare example of Ir(I)-catalyzed direct decarbonylation of α-quaternary aldehydes with broad substrate scope and good functional group compatibility via judicious selection of ligand. Theα-chirality is memorized in this decarbonylation process. In addition, we report a broad-spectrum decarbonylation of α-secondary and α-tertiary aldehydes containing multifunctional groups with an improved Rh(I)/DPPP recipe. Finally, we realized selective decarbonylation of α-tertiary aldehydes in the presence of α-quaternary one via the reactivity differences.

SDF-Based ILW:Inverse Lax-Wendroff Method with the Signed Distance Function Representation of the Geometric Boundary

This paper studies the geometric boundary representations for Inverse Lax-Wendroff(ILW)method,aiming to develop a practical computer-aided engineering method without body-fitted meshes.We propose the signed distance function(SDF)representation of the geometric boundary and design an extremely efficient algorithm for foot point calculation,which is particularly in line with the needs of ILW.Theoretical and numerical analyses demonstrate that the SDF representation of geometric boundary can satisfy ILW’s needs better than others.The effectiveness and robustness of our proposed method are verified by simulating initial boundary value computational physical problems of Euler equation for compressible fluids.

Flexible top-illuminated organic photodetector using an ultrathin-metal-based transparent electrode

Top-illuminated structure facilitates the integration of organic photodetectors(OPDs)into high-resolution flexible wearable light detection systems by allowing the OPDs to be deposited on the bottom readout circuit.However,constructing this structure poses a challenge as it demands metallic electrodes with both high optical transparency and high electrical conductivity.But to achieve practical sheet resistances,most semitransparent metallic electrodes tend to reflect a large portion of incident light instead of allowing it to be absorbed by the photoactive layer of the OPDs.This,in turn,results in reduced photocurrent generation.To address this issue,a semiconducting germanium(Ge)film is introduced into a sliver(Ag)film,effectively reducing its reflectivity by lessening scattering.The Ge film also changes how the Ag film grows,further reducing its absorption by lowering the critical thickness needed for forming a continuous film.This approach yields a 10 nm metallic electrode with a transmittance of 70%,a reflectivity of 12%,and a sheet resistance of 35.5Ω/□.Using this metallic electrode,flexible OPDs exhibit a high photo-to-dark current ratio of 2.9×10^(4)and improved mechanical properties.This finding highlights the benefits of the top-illuminated structure,which effectively reduces losses caused by waveguided modes of the incident light.

Top-emitting thermally activated delayed fluorescence organic light-emitting devices with weak light-matter coupling

Resonance interaction between a molecular transition and a confined electromagnetic field can lead to weak or strong light-matter coupling.Considering the substantial exciton–phonon coupling in thermally activated delayed fluorescence(TADF)materials,it is thus interesting to explore whether weak light-matter coupling can be used to redistribute optical density of states and to change the rate of radiative decay.Here,we demonstrate that the emission distribution of TADF emitters can be reshaped and narrowed in a top-emitting organic light-emitting device(OLED)with a weakly coupled microcavity.The Purcell effect of weak microcavity is found to be different for TADF emitters with different molecular orientations.We demonstrate that radiative rates of the TADF emitters with vertical orientation can be substantial increased in weakly coupled organic microcavity.These observations can enhance external quantum efficiencies,reduce efficiency roll-off,and improve color-purities of TADF OLEDs,especially for emitters without highly horizontal orientation.

A flexible,multifunctional,optoelectronic anticounterfeiting device from high-performance organic light-emitting paper

As a primary anticounterfeiting technology,most paper anticounterfeiting devices take advantage of photoresponsive behaviors of certain security materials or structures,thus featuring low-security threshold,which has been a critical global issue.To incorporate optoelectronic devices into existing anticounterfeiting technology suggests a feasible avenue to address this challenge.Here we report a high-performance organic light-emitting paper-based flexible anticounterfeiting(FAC)device with multiple stimuli-responsiveness,including light,electricity,and their combination.Without sacrificing the preexisted security information on the paper,we fabricate FAC device in a facile,low-cost yet high-fidelity fashion by integrating patterned electro-responsive and photo-responsive organic emitters onto paper substrates.By introducing optical microcavities,the FAC device shows considerable color shift upon different viewing angle and applied voltage,which is easily discernible by naked eyes.Notably,the FAC device is bendable,unclonable,and durable(a half-lifetime over 4000 hours at 100 cd m^(−2)).

High-surface-area titanium nitride nanosheets as zinc anode coating for dendrite-free rechargeable aqueous batteries

Aqueous zinc-ion batteries(AZIBs)have become attractive energy storage devices,owing to their high energy density,low cost,and environmental friendliness.However,the stability of the zinc-metal anode has been retarded by dendrites and side reactions during the cycling process,limiting its practical application in secondary batteries.In this work,porous titanium nitride(TiN)nanosheets with a high surface area are demonstrated as a multiplefunction anode coating to realize long-term dendrite-free AZIBs.The TiN nanosheets with the features of high specific surface area and metallic properties optimize electron conduction and zinc-ion flux,lowering the polarization on the electrode surface.In this way,the TiN-coated zinc electrodes exhibit a long cycle performance for more than 600 h without any dendrite formation.In addition,the full AZIB assembly based on the TiN-coated zinc electrode has a stable cycling performance for over 600 cycles with 97.04%capacity retention.This work expands applications of the inorganic porous materials as protective layers in high-energy battery systems.

Numerical simulation of a complex moving rigid body under the impingement of a shock wave in 3D

In this paper,we take a numerical simulation of a complex moving rigid body under the impingement of a shock wave in three-dimensional space.Both compressible inviscid fluid and viscous fluid are considered with suitable boundary conditions.We develop a high order numerical boundary treatment for the complex moving geometries based on finite difference methods on fixed Cartesian meshes.The method is an extension of the inverse Lax-Wendroff(ILW)procedure in our works(Cheng et al.,Appl Math Mech(Engl Ed)42:841-854,2021;Liu et al.)for 2D problems.Different from the 2D case,the local coordinate rotation in 3D required in the ILW procedure is not unique.We give a theoretical analysis to show that the boundary treatment is independent of the choice of the rotation,ensuring the method is feasible and valid.Both translation and rotation of the body are taken into account in this paper.In particular,we reformulate the material derivative for inviscid fluid on the moving boundary with no-penetration condition,which plays a key role in the proposed algorithm.Numerical simulations on the cylinder and sphere are given,demonstrating the good performance of our numerical boundary treatments.

A smart post-synthetic route towards[Fe_(2)Co_(2)]molecular capsules with electron transfer and bidirectional switching behaviors

Aldehyde groups were intentionally equipped on the cyanide-bridged[Fe_(2)Co_(2)]square molecules:{[(Tp*)Fe(CN)_(3)Co(bpy^(CHO))_(2)]_(2)-[PF_(6)]_(2)}·4MeOH(1,Tp*=hydrotris(3,5-dimethylpyrazol-1-yl)borate;bpy^(CHO)=4-formyl-4′-methyl-2,2′-bipyridine),thus providing chemical-active windows for post-modification towards desired functions.In this contribution,by taking advantage of efficient Schiff-base condensation between the aldehyde-substituted bipyridine derivative(bpyCHO)and alkyl diamines(H_(2)N-(CH_(2))_(n)NH_(2)),two discrete[Fe_(2)Co_(2)]compounds{[(Tp∗)Fe(CN)_(3)Co(bpy^(C=N(CH_(2))_(n)N=C)bpy)]2[PF_(6)]_(2)}⋅6DMF(2,n=5;3,n=7)were prepared,where the cyanide-bridged[Fe_(2)Co_(2)]square cores were encapsulated by the flexible alkyl chains.Variable-temperature single-crystal X-ray diffraction and magnetic studies revealed complete thermo(T_(1/2)=233 K(2)and 237 K(3))and photo-induced electron transfer event accompanying spin transition between the diamagnetic[Fe^(Ⅱ)_(LS2)Co^(Ⅲ)_(LS2)]state and the paramagnetic[Fe^(Ⅲ)_(LS2)Co^(Ⅱ)_(HS2)]state(LS,low spin;HS,high spin).In addition,the bidirectional switching between the two states was achieved with alternating laser irradiation at 808 and 532 nm at 10 K.

Secondary Metal Coordination Using a Tetranuclear Complex as Ligand Leading to Hexanuclear Complexes with Enhanced Thermal Barriers for Electron Transfer

Postsynthesis of the paramagnetic square-shaped complex{[(Tp*Me)Fe(μ-CN)_(2)(CN)][Co(dmbpy)_(2)]}_(2)(BPh_(4))_(2)·6MeCN·H2O[1,Tp*Me=tris(3,4,5-trimethylpyrazole)-borate;dmbpy=4,4′-dimethyl-2,2′-bipyridine)]by grafting transition metal(II)thiocyanates via its terminal cyano groups afforded three hexanuclear[Fe_(2)Co_(2)M_(2)]clusters(M=Zn,2;Co,3;Cd,4).The peripheral metal-complex units serving as excellent electron acceptors were found to help stabilize the low-temperature state of Fe^(II,LS)–Co^(III,LS) within the complex core.