Most current researches working on improving stiffness focus on the application of control *** controller in closed-loop hydraulic controlsystem takes effect only after the controlled position is deviated,so the cont...
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Most current researches working on improving stiffness focus on the application of control *** controller in closed-loop hydraulic controlsystem takes effect only after the controlled position is deviated,so the control action is *** dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advancedcontrol *** this paper,the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is *** this basis,the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put *** a scheme using double servo valves to realize flow feedforward compensation is presented,in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in *** two valves are arranged in parallel to control the cylinder ***,the model of flow compensation is derived,by which the product of the amplitude and width of the valve’s pulse command signal can be *** determination rules of the amplitude and width of pulse signal are concluded by analysis and *** the proposed scheme,simulations and experiments at different positions with different force changes are *** simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling *** is,system dynamic load stiffness is evidently *** paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.
In this work we introduce an innovative approach to single-molecule quantum coherence (SMQC)-based disposable micro-optical anti-counterfeiting labels. This method facilitates the editing and reading of anti-counterfe...
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With the rapid development of e-commerce and supply chain management, logistics demand forecasting and scheduling optimization have become key links in improving logistics efficiency and service quality. To meet this ...
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ISBN:
(数字)9798350389579
ISBN:
(纸本)9798350389586
With the rapid development of e-commerce and supply chain management, logistics demand forecasting and scheduling optimization have become key links in improving logistics efficiency and service quality. To meet this challenge, this paper proposes a logistics demand forecasting and scheduling optimization method that combines K-Means clustering with deep Q network (DQN). Cluster analysis is used to reduce data complexity, and deep reinforcement learning is used to achieve intelligent scheduling. First, the background, challenges and research motivation of logistics demand forecasting and scheduling optimization are introduced. Secondly, the research results in related fields are reviewed, and the shortcomings of current research are pointed out. Then, the K-Means clustering algorithm, deep $\mathbf{Q}$ network theory and specific models of logistics demand prediction and scheduling optimization are elaborated. Then, the performance of the proposed method is designed and tested. The experimental results show that the proposed method can significantly improve the accuracy of logistics demand prediction, up to 0.93, optimize scheduling strategies, reduce logistics costs, and improve customer satisfaction.
We demonstrate a flexible erbium-doped pulsed fiber laser which achieves the wavelength and pulse width tuning by adjusting an intracavity filter. The intracavity filter is flexible to achieve any of the different wav...
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We demonstrate a flexible erbium-doped pulsed fiber laser which achieves the wavelength and pulse width tuning by adjusting an intracavity filter. The intracavity filter is flexible to achieve any of the different wavelengths and bandwidths in the tuning range. The wavelength and width of pulse can be tuned in a range of - 20 nm and from - 0.8 ps to 87 ps, respectively. The flexible pulsed fiber laser can be accurately controlled, which is insensitive to environmental disturbance.
Remote Photoplethysmography (rPPG) is a non-contact method for measuring heart rate (HR) through facial video, breaking the constraints of contact measurements and offering broad application prospects. However, in rea...
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The hydraulic excavator energy-saving research mainly embodies the following three measures: to improve the performance of diesel engine and hydraulic component, to improve the hydraulic system, and to improve the po...
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The hydraulic excavator energy-saving research mainly embodies the following three measures: to improve the performance of diesel engine and hydraulic component, to improve the hydraulic system, and to improve the power matching of diesel-hydraulic system-actuator. Although the above measures have certain energy-saving effect, but because the hydraulic excavator load changes frequently and fluctuates dramatically, so the diesel engine often works in high-speed and light load condition, and the fuel consumption is higher. Therefore, in order to improve the economy of diesel engine in light load, and reduce the fuel consumption of hydraulic excavator, energy management concept is proposed based on diesel engine cylinder deactivation technology. By comparing the universal characteristic under diesel normal and deactivated cylinder condition, the mechanism that fuel consumption can be reduced significantly by adopting cylinder deactivation technology under part of loads condition can be clarified. The simulation models for hydraulic system and diesel engine are established by using AMESim software, and fuel combustion consumption by using cylinder-deactivation-technology is studied through digital simulation approach. In this way, the zone of cylinder deactivation is specified. The testing system for the excavator with this technology is set up based on simulated results, and the results show that the diesel engine can still work at high efficiency with part of loads after adopting this technology; fuel consumption is dropped down to 11% and 13% under economic and heavy-load mode respectively under the condition of driving requirements. The research provides references to the energy-saving study of the hydraulic excavators.
A simple method to fabricate one-dimensional(1-D) and two-dimensional(2-D) ordered micro- and nano-scale patterns is developed based on the original masters from optical discs, using nanoimprint technology and soft st...
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A simple method to fabricate one-dimensional(1-D) and two-dimensional(2-D) ordered micro- and nano-scale patterns is developed based on the original masters from optical discs, using nanoimprint technology and soft stamps. Polydimethylsiloxane(PDMS) was used to replicate the negative image of the 1-D grating pattern on the masters of CD-R, DVD-R and BD-R optical discs, respectively, and then the 1-D pattern on one of the PDMS stamps was transferred to a blank polycarbonate(PC) substrate by nanoimprint. The 2-D ordered patterns were fabricated by the second imprinting using another PDMS stamp. Different 2-D periodic patterns were obtained depending on the PDMS stamps and the angle between the two times of imprints. This method may provide a way for the fabrication of complex 2-D patterns using simple 1-D masters.
The generation and transition dynamics of random distributed multi-pulse are studied numerically and experimentally in the mode-locked fiber laser. The influence of various cavity parameters on the generation of multi...
The generation and transition dynamics of random distributed multi-pulse are studied numerically and experimentally in the mode-locked fiber laser. The influence of various cavity parameters on the generation of multi-pulse in the fiber laser is investigated and the random distributed multi-pulse with delta-like characteristics in the autocorrelation trace is generated numerically. The results show that the highly nonlinear fiber can significantly enhance the nonlinear effect in the cavity to effectively and quickly enter the multi-pulse region. By adding the highly nonlinear fiber to the fiber laser in the experiment, the random distributed multi-pulse is generated under appropriate polarization state and pump power, which is consistent with the simulation results. The transition dynamics of the variation in the number of pulses during the formation process of the random distributed multi-pulse is studied by using the time-stretch dispersive Fourier transform technology. The random distributed multi-pulse combines the advantages of both pulse and chaotic signals, with a higher peak-to-peak value and random distribution in the time interval between pulses. Our work provides fundamental insights into the evolution and dynamic behavior in random distributed multi-pulse and broaden its potential applications in the correlation fiber loop ring down sensing.
The micro-mechanism of the silicon-based waveguide surface smoothing is investigated systematically to explore the effects of silicon-hydrogen bonds on high-temperature hydrogen annealing waveguides. The effect of sil...
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The micro-mechanism of the silicon-based waveguide surface smoothing is investigated systematically to explore the effects of silicon-hydrogen bonds on high-temperature hydrogen annealing waveguides. The effect of silicon- hydrogen bonds on the surface migration movement of silicon atoms and the waveguide surface topography are revealed. The micro-migration from an upper state to a lower state of silicon atoms is driven by silicon- hydrogen bonding, which is the key to ameliorate the rough surface morphology of the silicon-based waveguide. The process of hydrogen annealing is experimentally validated based on the simulated parameters. The surface roughness declines from 1.523nm to 0.461 nm.
Perovskite solar cells(PSCs) have made great progress since 2009 and become the focus of current research. As an important part of PSCs, charge transporting materials play an important role in the performance of the d...
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Perovskite solar cells(PSCs) have made great progress since 2009 and become the focus of current research. As an important part of PSCs, charge transporting materials play an important role in the performance of the devices. In this review, we introduce the evolution of electron and hole transporting materials in PSCs in recent years and summarize some typical charge transporting materials and their applications in PSCs. For electron transporting materials, metal oxides(TiO_(2), SnO_(2) and ZnO) and organic materials(fullerenes, non-fullerenes and their derivatives)are the most widely used materials in PSCs. For hole transporting materials, small molecule spiro-OMeTAD(2,2’,7,7’-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9’-spirobifluorene), polymer PEDOT:PSS(poly(3,4-ethylenedioxythiophene): polystyrene sulfonate), PTAA(poly-[bi(4-phenyl)](2,4,3-trimethylphenyla-mine)), P3 HT(poly(3-hexythiophene)) and inorganic materials(NiOx, CuSCN, CuO) are adopted in PSCs. Finally, different types of charge transporting materials are summarized and their future development is prospected.
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