Hydrazine‐assisted water electrolysis provides new opportunities to enable energy‐saving hydrogen production while solve the issue of hydrazine pollution. Here, we report the synthesis of compressively strained Ni2P as a bifunctional electrocatalyst for boosting both the anodic hydrazine oxidation reaction (HzOR) and cathodic hydrogen evolution reaction (HER). Different from a multistep synthetic method that induces lattice strains by creating core‐shell structures, we develop a facile strategy to tune strains of Ni2P via the dual cation‐codoping. The obtained Ni2P with a compressive strain of −3.62% exhibits significantly enhanced activity for both the HzOR and HER than counterpart with tensile strains and without strains. Consequently, the optimized Ni2P delivers current densities of 10 and 100 mA cm−2 at small cell voltages of 0.16 and 0.39 V for hydrazine‐assisted water electrolysis, respectively. Density functional theory (DFT) calculations reveal that the compression strain promotes water dissociation and concurrently tunes the adsorption strength of hydrogen intermediates, thereby facilitating the HER process on Ni2P. As for the HzOR, the compression strain reduces the energy barrier of potential‐determining step (PDS) for the dehydrogenation of *N2H4 to *N2H3. Clearly, this work not only paves a facile pathway to synthesis lattice‐strained electrocatalysts via the dual cations‐codoping.This article is protected by copyright. All rights reserved

The core component, TBM cutterhead, bears a multi-directional impact load because of its direct contact with rock during tunneling. Unreasonable cutter design and parameter set lead to severe vibration or abnormal injury during excavation, seriously affecting the efficiency of the TBM tunneling. Therefore, study of cutterhead dynamics response under impact loads is one of the core content of TBM system design. TBM multi-degree-of-freedom coupled dynamic model contains different geological conditions, cutter speed, body mass, time-varying mesh stiffness, transmission error, etc. A method is proposed to solve the problem based on Newmark algorithm, which further improves the solution efficiency. A tunneling field test was conducted, and the results verify the correctness of the model and the simplified cutter system. The simulation results of the Dahuofang project show that: ① The calculation process of Newmark is simplified, the calculation speed increased 3-4 orders of magnitude higher than Runge-Kutta method, while the solving time was reduced from 2.6e5 s to 155 s under the same precision; ② Compared with the results of two kinds of rock with compressive strength 150 MPa and 95 MPa, the translational vibration amplitude ratio is 3.33 and axial vibration amplitude ratio is 2.08. It indicates that as the rock compressive strength increases, the growth of the cutterhead's vibration amplitude increase accelerated, rather than proportional increases; ③ The vibration decreases along with the cutter speed becomes larger and the system becomes stabilized when the cutterhead speed turns into 4r/min. The cutter head speed clearly affects torsional, lateral and longitudinal vibration. The change rate has reached 0.53-0.61. Therefore, TBM should choose the right cutter speed to avoid bearing damage, seal failure and other serious accidents; ④ The translational vibration of components decreases with the components' mass increase. It has the greatest impact on the horizontal and vertical vibration of the big ring. The vibration changing rate of the big ring reaches 0.31. The big ring has almost no effect on the axial vibration and overturn, but the energy consumed on rock cutting will be reduced as the mass increases. Body weight should be chosen reasonably considering vibration,construction economy and internal excitation of parameters. The above conclusions provide a theoretical basis for TBM dynamics optimization design, vibration control and cutterhead architecture design.

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Damage by excessive vibration is serious engineering problem in TBM boring process. Dynamic characteristic analysis is essential for TBM antivibration design. According to TBM horizontal support structure, a dynamic coupling nonlinear model is established, with consideration of time-varying impact load and multicomponent complex relationship from cutter to gripper shoe. A set of field vibration tests is set up to accurately collect data under extreme work conditions; then, field data is collected from Liaoning northwest engineering. Field data is applied to validate simulation model to make sure time-varying damping stiffness, support cylinder stiffness, and the TBM machine stiffness distribution are reasonable. Simulation indicates the weakest part of TBM in axial and torsional DOF is the cylinder hinge and the connection shaft between motor and pinion, and the horizontal and vertical weak parts are bull gear. It also shows that, in normal excavation conditions, the acceleration amplitude of the cutterhead in three directions ranges from 1.5 g to 2 g. These results provide theoretical basis for the antivibration design and structural optimization of TBM.

As the main bearing components of vehicle wheel/rail systems, railway bearings take on the main load of wheel/rail system. These bearings can be easily damaged after a long-term load, which causes vibrations and significant deterioration of force distribution and directly affects the driving stability of the locomotive. Current systems available for modeling the dynamics of wheel/rail systems rarely consider nonlinear contact load bearing, which causes errors in the calculation of wheel/rail system dynamics. According to the bearing structure characteristics and working features of a specific system, this paper thoroughly evaluates the flexible deformation of shaft and bearing, time-varying nonlinear contact load, track irregularity, and bearing to establish a wheel/rail system coupling dynamics model. Then, based on the coupling dynamics theoretical model, the wheel/rail system’s coupling nonlinear dynamic characteristics are studied under random load. Then, this theoretical model of the wheel–bearing–rail system dynamics is verified using the railway bearing as an example. Finally, the model is applied to the process of rail/wheel low force design. Results show that under irregular stimulation, the maximum contact load increased by 71.2% and the maximum contact stress increased by 19.6%. After moderate wear, the wheel/rail system vibration and loading condition deteriorate rapidly. Under the low rail/wheel force, the wheel tread and diameter had significant effects on wheel/rail contact force distribution. The rail specifications are found to affect the wheel/rail system’s vibration significantly. This paper has important theoretical value and practical significance for developing reliable railway bearings and wheel/rail systems with good static/dynamic characteristics that can withstand dynamic impact load.