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Due to the similarity in wavelength between millimeter-wave (MMW) signals and raindrop diameters, rainfall induces significant attenuation and scattering effects that challenge the detection performance of MMW fuzes in rainy environments. To enhance the adaptability of frequency-modulated MMW fuzes in such conditions, the effects of rain on MMW signal attenuation and scattering are investigated. A mathematical model for the multipath echo signals of the fuze was developed. The Monte Carlo method was employed to simulate echo signals considering multiple scattering, and experimental validations were conducted. The results from simulations and experiments revealed that rainfall increases the bottom noise of the echo signal, with rain backscatter noise predominantly affecting the lower end of the echo signal spectrum. However, rain conditions below torrential levels did not significantly impact the detection of strong reflection targets at the high end of the spectrum. The modeling approach and findings presented offer theoretical support for designing MMW fuzes with improved environmental adaptability. [ABSTRACT FROM AUTHOR]

In the environment of smoke and suspended particles, the accurate detection of targets is one of the difficulties for frequency-modulated continuous-wave (FMCW) laser fuzes to work properly in harsh conditions. To weaken and eliminate the significant influence caused by the interaction of different systems in the photon transmission process and the smoke particle environment, it is necessary to increase the amplitude of the target echo signal to improve the signal-to-noise ratio (SNR), which contributes to enhancing the detection performance of the laser fuze for the ground target in the smoke. Under these conditions, the particle transmission of photons in the smoke environment is studied from the perspective of three-dimentional (3D) collisions between photons and smoke particles, and the modeling and Unity3D simulation of FMCW laser echo signal based on 3D particle collision is conducted. On this basis, a laser fuze structure based on multiple channel beam emission is designed for the combined effect of particle features from different systems and its impact on the target characteristics is researched. Simulation results show that the multiple channel laser emission enhances the laser target echo signal amplitude and also improves the anti-interference ability against the combined effects of multiple particle features compared with the single channel. Through the validation based on the laser prototype with four-channel beam emitting, the above conclusions are supported by the experimental results. Therefore, this study not only reveals the laser target properties under the 3D particle collision perspective, but also reflects the reasonableness and effectiveness of utilizing the target characteristics in the 3D particle collision mode to enhance the detection performance of FMCW laser fuze in the smoke. [ABSTRACT FROM AUTHOR]

The increasingly complex electromagnetic environment of modern warfare and the proliferation of intelligent jamming threaten to reduce the survival rate of radio fuzes on the battlefield. Radio frequency (RF) stealth technology can fundamentally improve the anti-interception and reconnaissance capabilities of radio fuzes, thereby lessening the probability of them being intercepted, recognized, and jammed by the enemy. In this paper, an RF stealth waveform based on chaotic pulse-position modulation is proposed for ultra-wideband (UWB) radio fuzes. Adding a perturbation signal based on the Tent map ensures that the chaotic sequences have sufficiently long periods despite hardware byte limitations. Measuring the approximate entropy and sequence period shows that the Tent map with the addition of perturbation signals can maintain good randomness under byte constraints, closely approximating the Tent map with ideal precision. Simulations verify that the proposed chaotic mapping used to modulate the pulse position of an ultra-wideband radio fuze signal results in superior detection, anti-interception, and anti-jamming performance. [ABSTRACT FROM AUTHOR]

To improve the ride comfort of the vehicle and the high-efficiency control requirements of the suspension, this paper proposes a time-delay control strategy and the idea of using a linear motor as the actuator. This paper analyses the damping characteristics of the time-delay control strategy in the time domain and frequency domains. A linear equivalent excitation method is proposed to optimise the optimal time-delay control parameters under complex excitations. The stability of the system is analysed. The damping effect of time-delay control active suspension is verified by numerical simulation. An experimental hardware platform of a linear motor and active suspension was built further to verify the effectiveness of the time-delay control strategy. The experimental results show that the relative errors of root mean square values of experimental and simulation results are within 16% under each working condition. The experimental results verify the effectiveness of the simulation results. [ABSTRACT FROM AUTHOR]

Time‐delay significantly impacts the control system's performance and even leads to the unexpected instability of the control system. This paper aims at the adverse effect of time‐delay on the control effect and stability of the active suspension system. This paper proposes to suppress vehicle body vibration by applying time‐delay displacement feedback. In this paper, the time‐delay control characteristics of the system are studied by combining theory with experiment. This paper first establishes the suspension system's dynamic Equation with time‐delay. Then, the frequency domain sweep method is used to analyze the stability of the control system. Finally, the time‐delay simulation model is established, and the single‐frequency excitation is used as the external excitation to compare with passive and backstepping control. The simulation results verify the superiority of the time‐delay control under external excitation. In this paper, through the 1/4 model bench test of the active suspension system, the simulation results and the test results under the same working conditions are compared, and it is found that the two have good consistency. The results show that the research is credible and can provide a reference for the actual design and application of active vehicle suspension controllers. [ABSTRACT FROM AUTHOR]

Selective electron beam melting (SEBM) has been recently employed for additive manufacturing (AM) Al alloys but showing comparatively low hardness and strength. In this work, SEBM technique was employed to additive manufacture an in-situ TiB2 particle reinforced AlSi10Mg composite. With optimized processing parameters, the SEBM TiB2/AlSi10Mg composite showed good surface quality and a high relative density. The as-printed composite exhibited a refined equiaxed grain structure with an average size of 27.7 µm. The eutectic Si phase was mostly spherical and uniformly distributed in the Al matrix, while the nano-sized TiB2 particles were partly agglomerated. The resultant microstructure was associated with the combined effect of the rapid solidification and annealing-like process during SEBM. Additionally, TiB2 particles facilitated grain refinement by enhancing the heterogeneous nucleation and retarding grain growth. The SEBM TiB2/AlSi10Mg composite presented a yield strength (YS) and ultimate tensile strength (UTS) of 103.6 MPa and 165.4 MPa, respectively, with an appreciable elongation of 15% at as-printed state. After a T6-like treatment, the YS and UTS of the composite were further improved to 225 MPa and 316 MPa, respectively, and an elongation of 12% was maintained. This paper shows the potency of SEBM in AM metal matrix composites (MMCs) with both agreeable strength and ductility. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic vibration absorber considering time delay is taken as the research object, and the effect of time delay on the vibration characteristics of the dynamic vibration absorber is studied by combining theory and experiment. In this paper, a time-varying time-delay feedback control method is proposed. Firstly, the instantaneous frequency of complex excitation is obtained by wavelet analysis. The instantaneous frequency determines the critical time-delay parameters of the dynamic vibration absorber with time-delay as the time-delay control quantity. Then, the optimal fixed time-delay feedback gain is calculated by improved particle swarm optimization. Finally, the time-varying delay gain parameter controls the time-delay dynamic vibration absorber. The vibration reduction effect of this approach under complicated excitation is investigated using a 2-DOF vibration system with a time-delay dynamic vibration absorber as an example. Based on simulation calculation, the bench test of the control strategy is carried out, and the influence of the control strategy on the control dynamic characteristics of the primary system is analyzed. The simulation and experimental results are consistent, laying the groundwork for this paper's research on time-varying delay control. [ABSTRACT FROM AUTHOR]

Preparing low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction using a simple strategy still faces challenges. In this work, we proposed a facile phosphating process to successfully transform CoFe-BTC (BTC = 1,3,5-benzenetricarboxylate) precursors into carbon-incorporated bimetallic phosphide (CoFe-P/C) nanospheres. Due to the synergistic effect between bimetals and uniformly covered carbon shells outside, the as-synthesized porous bimetallic phosphide nanospheres exhibit superior HER activity, enhanced kinetics, and excellent cycle durability in both acidic and alkaline solutions. The optimized material could afford a current density of 10 mA cm−2 with overpotentials of 138 and 193 mV for the HER in acidic and alkaline solutions, respectively. Meanwhile, it delivered small Tafel slopes of 84 and 78 mV dec−1 for the HER in 0.5 M H2SO4 and 1.0 M KOH, respectively. Moreover, an assembled alkaline electrolyzer enabled a low voltage of 1.62 V to drive a current density of 10 mA cm−2 for overall water splitting. DFT calculations indicate that the CoP–Fe2P composite is supposed to exhibit better HER performance than each component, revealing the vital role of the interfacial site in catalyzing the HER. [ABSTRACT FROM AUTHOR]

The hydraulic accumulator has the advantages of high power density, fast response, stable operation and high cost performance. However, compared with the electric energy storage method, the hydraulic accumulator has low energy density and large pressure fluctuation while absorbing and discharging energy, which severely limits its application in hydraulic excavators. To improve the potential energy loss of the boom during the lowering process, an electro-hydraulic drive and energy recovery system for excavator booms (EHDR-EEB) based on a battery and accumulator is proposed. As a result, a simulation model of the electro-hydraulic drive and energy management strategy of a 1.6 t pure electric hydraulic excavator is built to investigate the energy regeneration and utilization. The simulation outcomes show that the potential energy recovery rate is as high as 92%. This research on EHDR-EEB makes a significant contribution to the economic improvement of electric hydraulic excavators. [ABSTRACT FROM AUTHOR]

This study introduces time-delay active control technology to with the aim of enhancing the system's energy harvesting potential and ride smoothness. The time-delay active suspension represents a nonlinear, multivariable system, and stability analysis in this context is intricate. The mainly challenge lies in effectively leveraging time delay to augment the system's energy collection potential while harmonizing the vehicle's ride comfort and energy efficiency. Addressing this issue, our study proposes enhancing the suspension's energy recovery capability through time-delay control. Initially, the impact of time-delay control parameters on energy collection ability under various operational conditions was analyzed, establishing that appropriate time-delay parameters can enhance energy harvesting capacity. Subsequently, to balance the relationship between vehicle comfort and energy efficiency, the research introduces a method for constructing an optimized objective function based on linear equivalent excitation, thereby quantifying the relationship between system time-domain vibrational response, time-delay control parameters, and external excitations. This approach enables the comprehensive optimization of the suspension system's comfort, safety, and energy efficiency. The control system's stability was analyzed using cluster treatment of characteristic roots method. Finally, simulations and experiments were conducted to evaluate the effectiveness of time-delay active across different scenarios, confirming the efficacy of the proposed control methodology. • Harnessing time-delay control enhances energy harvesting. • Methods are proposed to improve vehicle comfort and energy harvesting. • Reasonable time-delay control parameters can enhance energy harvesting. • Provide a reference for suspension energy harvesting. [ABSTRACT FROM AUTHOR]

Time-delay feedback control can effectively broaden the damping frequency band and improve the damping efficiency. However, the existing time-delay feedback control strategy has no obvious effect on multi-frequency random excitation vibration reduction control. That is, when the frequency of external excitation is more complicated, there is no better way to obtain the best time-delay feedback control parameters. To overcome this issue, this paper is the first work of proposing an optimal calculation method that introduces stochastic excitation into the process of solving the delay feedback control parameters. It is a time-delay control parameter with a better damping effect for random excitation. In this paper, a 2 DOF one-quarter vehicle suspension model with time-delay is studied. First, the stability interval of time-delay feedback control parameters is solved by using the Lyapunov stability theory. Second, the optimal control parameters of the time-delay feedback control under random excitation are solved by particle swarm optimization (PSO). Finally, the simulation models of a one-quarter vehicle suspension simulation model are established. Random excitation and harmonic excitation are used as inputs. The response of the vehicle body under the frequency domain damping control method and the proposed control method is compared and simulated. To make the control precision higher and the solution speed faster, this paper simulates the model by using the precise integration method of transient history. The simulation results show that the acceleration of the vehicle body in the proposed control method is 13.05% less than the passive vibration absorber under random excitation. Compared with the time-delay feedback control optimized by frequency response function, the damping effect is 12.99%. The results show that the vibration displacement, vibration velocity, and vibration acceleration of the vehicle body are better than the frequency domain function optimization method, whether it is harmonic excitation or random excitation. The ride comfort of the vehicle is improved obviously. It provides a valuable tool for time-delay vibration reduction control under random excitation. [ABSTRACT FROM AUTHOR]

As one of commonly used platforms for BIM design of urban rail transit, Revit has built-in rich design tools in professional engineering such as architecture and structure, which can realize efficient BIM modeling. The urban rail transit track project is belt-shaped under a spatial curve, and the existing Revit platform cannot meet the efficient modeling needs of professional designers. In response to this problem, based on the professional design experience of the track, combined with the characteristics of the software of the Revit platform, this paper proposed a method to quickly realize the BIM modeling of the track under the Revit platform. Through the Dynamo visual programming tool under the Revit platform, a special tool was developed to read the basic data of the horizontal and vertical section of the line and directly calculate the line space position and direction, and then automatically called various rail Revit adaptive components for rails and sleepers. The arrangement of fasteners and track bed realizes the efficient modeling of track BIM, which can a provide reference for the BIM design of similar projects. [ABSTRACT FROM AUTHOR]

Vehicles driving on the road continuously suffer low-frequency and high-intensity road excitation, which can cause the occupant feelings of tension and dizziness. To solve this problem, a three-degree-of-freedom vehicle suspension system model including vehicle seat is established and a linear function equivalent excitation method is proposed. The optimization of the random excitation is transformed into the optimization of constant force in a discrete time interval, which introduces the adaptive weighted particle swarm optimization algorithm to optimize the delay and feedback gain parameters in the feedback control of time delay. In this paper, the stability switching theory is used for the first time to analyze the stability interval of 3-DOF time-delay controlled active suspension, which ensures the stability of the control system. The numerical simulation results show that the algorithm can reduce vertical passenger acceleration and vehicle acceleration, respectively, by 13.63% and 28.38% on average, and 29.99% and 47.23% on random excitation, compared with active suspension and passive suspension based on inverse control. The effectiveness of the method to suppress road random interference is verified, which provides a theoretical reference for further study of suspension performance optimization with time-delay control. [ABSTRACT FROM AUTHOR]

Suspension system is one of the important parts of a vehicle, which is used to buffer the impact of uneven road to the body and passengers, so the suspension system has an important impact on the safety and ride comfort of the vehicle. In order to improve the safety and comfort of passengers and vehicles, in this paper a five-degree-of-freedom half car model is established, and the uncertainty of the model and the time-delay of the control are considered. The dynamic response of vehicle body acceleration root mean square, passenger acceleration root mean square, displacement root mean square and vehicle body pitch acceleration root mean square are selected as optimization objectives. The time-delay control parameters are determined by chaos particle swarm optimization algorithm. The time-delay stability of the suspension control system is analyzed by frequency-domain scanning method to ensure the stability of the time-delay control system. Finally, by establishing the simulation model of the active suspension system with double time-delay feedback control, the response characteristics of the suspension system with double time-delay active feedback control to simple harmonic excitation and random excitation input are analyzed. The results show that under the premise of ensuring the system stability, the active suspension system with double time-delay feedback control has good and obvious controlling and damping effect on the body and seats. [ABSTRACT FROM AUTHOR]

With the application of an active control unit in the suspension system, the phenomenon of time delay has become an important factor in the control system. Aiming at the application of time-delay feedback control in vehicle active suspension systems, this paper has researched the dynamic behavior of semivehicle four-degree-of-freedom structure including an active suspension with double time-delay feedback control, focusing on analyzing the vibration response and stability of the main vibration system of the structure. The optimal objective function is established according to the amplitude-frequency characteristics of the system, and the optimal time-delay control parameters are obtained by using the particle swarm optimization algorithm. The stability for active suspension with double time-delay feedback control by frequency-domain scanning method is analyzed, and the simulation model of active suspension with double time delay based on feedback control is finally established. The simulation results show that the active suspension with double time-delay feedback control could reduce the body's vertical vibration acceleration, pitch acceleration, and other indicators significantly, whether under harmonic excitation or random excitation. So, it is indicating that the active suspension with double time-delay feedback control has a better control effect in improving the ride comfort of the car, and it has important reference value for further research on suspension performance optimization. [ABSTRACT FROM AUTHOR]

Aim: We aimed to investigate the proteomics of primary chondrocyte exosomes and the effect of exosomes in osteoarthritis (OA) treatment. Materials & methods: We isolated exosomes from primary chondrocytes cultured in normal (D0) and inflammatory environments induced by IL-1β and determined the proteomics of these exosomes. Next, we investigated what effect and mechanism D0 chondrocytes exosomes have in OA treatment. Results: There were more proteins that belonged to mitochondrion and were involved in immune system processes in D0 exosomes. Notably, intra-articular administration of D0 exosomes successfully prevented the development of OA. D0 chondrocyte exosomes could restore mitochondrial dysfunction and polarize macrophage response toward an M2 phenotype. Conclusion: Our findings demonstrated that primary chondrocyte exosomes are efficient in OA treatment. [ABSTRACT FROM AUTHOR]

The existing available research outcomes on vibration attenuation control for time-delay feedback indicate that, for the delay dynamic vibration absorber with fixed time-delay control parameters, under harmonic excitation, a good vibration attenuation control effect occurs on the vibration of the main system. However, the effect is not obvious for complex excitation. Aiming at the above problems, in a short time interval, a harmonic excitation with the same displacement size as the complex excitation was established. Then, by calculating its equivalent amplitude and equivalent frequency, a harmonic equivalent method for complex excitation was proposed in this paper. The time-delay parameters were adjusted according to the equivalent frequency of harmonic equivalent excitation in real time; therefore, a good vibration attenuation control effect was obtained through the delay dynamic vibration absorber in the discrete time interval. In this paper, research on a time-varying delay dynamic vibration absorber was conducted by taking the two-degree-of-freedom vibration system with a delay dynamic vibration absorber as an example. The simulation results show that the proposed control method can reduce the vibration of the main system by about 30% compared with the passive vibration absorber. This can obviously improve the performance of the time-delay dynamic vibration absorber. It provides a new technical idea for the design of vehicle active frame system. [ABSTRACT FROM AUTHOR]

As the main energy consumption terminal and emission source, the engine is expected to achieve zero carbon emission with the help of hydrogen energy. Focusing on the current status and difficult issues of hydrogen engine research, this paper firstly emphasizes the importance of applying hydrogen energy in the future development of engines, secondly reviews and summarizes the development of hydrogen engines in terms of traditional structural inheritance and innovation, and then provides updated ideas for the development route of pure hydrogen fuel and the promotion of hydrogen fuel applications from the perspective of new combined fuels and industrialization challenges. A summary of the classification of hydrogen engine operating strategies is included to point out the prevailing regulation and influencing factors on hydrogen engines and the understanding of the working process. The obstacles to industrialization are related to a broader field, besides the field of scientific research, there are issues of infrastructure development, cost control, and safety standards development. • Different ignition and injection methods and mechanisms of hydrogen engines are investigated. • The inheritances and innovations of the hydrogen engine on the traditional structure are investigated. • Hydrogen engine working strategies are classified into four categories. • Blend fuels and clean alternative fuels other than hydrogen are investigated. • The challenges faced in the industrialization of hydrogen engines are investigated. [ABSTRACT FROM AUTHOR]

In the context of globalization where new energy vehicles are widely used, this paper proposes a novel mechanical-electro-hydraulic power coupling system for electric vehicles (MEHV). The planetary gear mechanism (PDCM) is integrated with the accumulator, hydraulic pump/motor, battery and motor to realize the mutual conversion of mechanical energy, electric energy and hydraulic energy. Subsequently, a rule-based energy management strategy is established to distribute energy and realize smooth switching in real time. Then, further analysis is carried out on the electro-hydraulic torque distribution. The results illustrate that, the peak torque of the drive motor (DM) can be decreased, and the hydraulic energy can be fully utilized to improve the state of charge (SOC) under appropriate ratio. Simultaneously, to ensure the appropriate electro-hydraulic ratio under complicated conditions, this paper adopts the fuzzy rule-based energy management strategy of multi-parameter input. Ultimately, the actual driving conditions are established using the actual driving data and the strategy. Consequently, the peak torque is significantly lower than pure electric vehicle, the battery energy consumption is reduced by 19.06%. Therefore, the approach proposed in this paper notably improves the running state of the motor, the energy utilization rate, as well as the economy and stability of the vehicle. • A novel mechanical-electro-hydraulic power coupling system is proposed. • A power flow analysis method based on bond graph theory is proposed. • An analysis of electro-hydraulic ratios is presented by a rule-based strategy. • The electro-hydraulic ratio is optimized according to fuzzy control strategy. • Actual results are analyzed by actual data collection and simulation. [ABSTRACT FROM AUTHOR]