In this paper, we first study a generalized canonical correlation analysis (CCA)-based fault detection (FD) method aiming at maximizing the fault detectability under an acceptable false alarm rate. ...More specifically, two residual signals are generated for detecting of faults in input and output subspaces, respectively. The minimum covariances of the two residual signals are achieved by taking the correlation between input and output into account. Considering the limited application scope of the generalized CCA due to the Gaussian assumption on the process noises, an FD technique combining the generalized CCA with the threshold-setting based on the randomized algorithm is proposed and applied to the simulated traction drive control system of high-speed trains. The achieved results show that the proposed method is able to improve the detection performance significantly in comparison with the standard generalized CCA-based FD method.
This paper analyzes the characteristics of the transportation system and constructs a multidimensional urban public transportation evaluation index system from the perspective of basic network ...evaluation. The DEA efficiency evaluation model is constructed based on the perspective of environmental and social issues in transportation systems. Environmental and social issues in transportation systems refer to the differences in the average number of people carried and their technical indicators such as environmental pollution and energy consumption for different modes of transportation, which will also lead to different consumption of natural resources per unit of transportation capacity. The multidimensional public transportation system efficiency evaluation system for different evaluation scenarios provides useful technical ideas and implementation methods. To provide a basis for decision-making for transportation system planning, the operation management can help to further promote the research results in practice.
The development of low‐cost and high‐efficiency catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolyte is still challenging. Herein, ...interfacial Co/CoMoN heterostructures supported on Ni foam (Co/CoMoN/NF) are constructed by thermal ammonolysis of CoMoOx. In 1.0 m KOH solution, Co/CoMoN/NF heterostructures exhibit excellent HER activity with an overpotential of 173 mV at 100 mA cm−2 and a Tafel slope of 68.9 mV dec−1. Density functional theory calculations indicate that the low valence state Co site acts as efficient water‐dissociation promoter, while CoMoN substrate has favorable hydrogen adsorption energy, leading to an enhanced HER activity. The Co/CoMoN/NF heterostructures also achieve high OER activity with an overpotential of 303 mV at 100 mA cm−2 and a Tafel slope of 56 mV dec−1. Using Co/CoMoN/NF heterostructures as the cathode and anode, the alkaline electrolyzer requires a low voltage of 1.56 V to reach the current density of 100 mA cm−2 along with superior long‐term durability. This study provides a new design strategy toward low‐cost and excellent catalysts for water splitting.
Co/CoMoN/NF exhibits excellent electrochemical water splitting performance in alkaline media via construction of interfacial heterostructures.
In recent years, the advantages of nonlinearity in vibration isolation and energy harvesting have become increasingly apparent. The quasi-zero stiffness (QZS) of the nonlinear term provided by the ...negative stiffness element can achieve vibration isolation under low-frequency environments while improving the efficiency of energy harvesting. The QZS provides a new research idea for simultaneous vibration isolation and energy harvesting. The main purpose of this paper is to review past research results, summarize possible problems, and discuss trends. After briefly analyzing the basic principle of QZS vibration isolation, the progress of QZS in vibration isolation and energy harvesting in recent years is reviewed. At the same time, main challenges of QZS in realizing synchronous vibration isolation and energy harvesting are also discussed. Finally, according to the existing QZS challenges, the future development trend of QZS is proposed. This paper would provide a quick guide for future newcomers to this field.
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•The formation mechanism of Li7P3S11 electrolyte in acetonitrile is studied.•The reaction in liquid is lone pair electrons on Li2S attacking bridge S on P2S5.•The precipitate and ...soluble phases are Li3PS4·ACN and Li4P2S7·ACN, respectively.•Low conductivity of liquid-phase synthesized Li7P3S11 is due to residual Li4P2S6.•Soluble Li4P2S7 can be obtained by reacting Li3PS4 with Li2P4S11 or Li4P4S12, etc.
All-solid-state lithium batteries have been recognized as the next generation energy storage/conversion devices for many high-power and safe applications. Li7P3S11 glass ceramics, as a promising solid electrolyte, has shown a high application possibility. Although the synthesis of Li7P3S11 by wet-chemical method is more controllable and can be well matched with the existing battery preparation processes, the chemical reaction mechanism of such a liquid-phase reaction process is not fully understood, and also its ionic conductivity is lower than that obtained by solid-state methods. In this paper, we have clarified that the liquid-phase reaction is mainly the process of lone-pair electrons of Li2S to attack the bridged S on P2S5 to obtain compounds with different element ratios, which is explored by recording different reaction times and adjusting different proportions of the phase transitions in acetonitrile (ACN) solvent. The only precipitate phase is found to be Li3PS4·ACN, which can react with soluble phases with higher P content such as Li2P4S11, Li4P4S12 and so on to obtain Li4P2S7 for the formation of Li3PS4·ACN and Li4P2S7·ACN (molar ratio 1:1) in the liquid phase. Finally, Li7P3S11 is formed by the equimolar reaction of above two compounds during the calcination. XPS and Raman results indicate that the low conductivity of liquid-phase synthesized Li7P3S11 solid electrolyte may be induced by the residual Li4P2S6, which is caused by the inadequate contact and coverage of gel-like Li4P2S7 with solid Li3PS4, resulting in the desulfurization reaction of Li4P2S7 during the heat-treatment.
Object detection under hazy weather conditions is a huge challenge due to the serious obscuration by fog. Recently, to improve detection accuracy in inclement weather, some excellent specifically ...designed algorithms for foggy conditions have been presented to identify objects from hazy images. However, applied to the detection task in hazy weather, state-of-the-art (SOTA) solutions have to change the architectures and training parameters of existing widely used original object detectors for clear weather, resulting in the waste of resources. To deal with this problem, in this work we propose a plug-and-play aerial object detector under foggy conditions, without the need of altering the structures and retraining the parameters of original task networks at all. The proposed algorithm includes an image enhancement and fusion branch working with a well-known SOTA object detection network for fine weather conditions, where this original detector is completely intact. The novel branch consists of a haze feature elimination module and an object feature restoration module, which are developed to remove fog information and recover clean object feature pyramid, respectively. Moreover, we also propose a detection feature pyramid loss function to more accurately restore object features. Experimental results show that the proposed plug-and-play aerial object detection framework performs well in not only fine weather but hazy weather conditions, while remaining the architecture and parameters of the original detection task network unchanged. This proposed flexible framework can be adapted to adverse weather conditions in all situations.
For ensuring the safety and reliability of high-speed trains, fault diagnosis (FD) technique plays an important role. Benefiting from the rapid developments of artificial intelligence, intelligent FD ...(IFD) strategies have obtained much attention in the field of academics and applications, where the qualitative approach is an important branch. Therefore, this survey will present a comprehensive review of these qualitative approaches from both theoretical and practical aspects. The primary task of this paper is to review the current development of these qualitative IFD techniques and then to present some of the latest results. Another major focus of our research is to introduce the background of high-speed trains, like the composition of the core subsystems, system structure, etc., based on which it becomes convenient for researchers to extract the diagnostic knowledge of high-speed trains, where the purpose is to understand how to use these types of knowledge. By reasonable utilization of the knowledge, it is hopeful to address various challenges caused by the coupling among subsystems of high-speed trains. Furthermore, future research trends for qualitative IFD approaches are also presented.
Mitochondria are responsible for providing energy currency to life processes in the molecular form of ATP and are therefore typically referred to as the power factories of cells. Plant mitochondria ...are also relevant to the common phenomenon of cytoplasmic male sterility, which is agronomically important in various crop species. Cytoplasmic male sterility (CMS) is a complex trait that may be influenced by patterns of mitochondrial genome evolution, and by intergenomic gene transfer among the organellar and nuclear compartments of plant cells. Here, we review patterns and processes that shape plant mitochondrial genomes, some relevant interactions between organelles, and the general features shared by the majority of cytoplasmic male-sterile genes in plants to further the goal of understanding CMS.
Simultaneous vibration isolation and energy harvesting (SVIEH) are becoming increasingly attractive in suspension systems. However, there is a conflict between low natural frequency and large loading ...capacity. In addition, the energy harvesting performance is always limited by maintaining the vibration isolation performance in most existing studies. Therefore, how to enhance vibration energy harvesting while satisfying vibration isolation is still a challenge. In this paper, a pair of magnetic rings is used to generate quasi-zero stiffness (QZS) for dealing with the conflict between large loading capacity and low natural frequency, and a Halbach magnetic ring is presented to enhance the energy harvesting performance. Based on them, a novel low-frequency QZS-based SVIEH (QZS-SVIEH) structure is proposed. Firstly, the structural condition of generating QZS is derived. Next the electro-mechanical coupling equations of the QZS-SVIEH system are built and solved by using the harmonic balance method (HBM), which is also verified by the Runge-Kutta method. Then the displacement transmissibility and output power are defined as the two performance indicators for vibration isolation and energy harvesting, respectively. The effects of electrical and mechanical parameters on the two performance indicators are studied in detail. Finally, the prototype of the proposed QZS-SVIEH structure is constructed for experimental testing. The experimental results show that the QZS-SVIEH can effectively suppress vibrations with frequencies above 7.2Hz and generate the peak power of 0.8W under the excitation of acceleration 1.5g and frequency 10Hz.
Sensor faults are one of the most common faults that cause performance degradation or functional loss in permanent magnet traction drive systems (PMTDSs). To quickly diagnose faulty sensors, this ...paper proposes a real-time joint diagnosis method for multi-sensor faults based on structural analysis. Firstly, based on limited monitoring signals on board, a structured model of the system was established using the structural analysis method. The isolation and detectability of faulty sensors were analyzed using the Dulmage-Mendelsohn decomposition method. Secondly, the minimum collision set method was used to calculate the minimum overdetermined equation set, transforming the higher-order system model into multiple related subsystem models, thereby reducing modeling complexity and facilitating system implementation. Next, residual vectors were constructed based on multiple subsystem models, and fault detection and isolation strategies were designed using the correlation between each subsystem model and the relevant sensors. The validation results of the physical testing platform based on online fault data recordings showed that the proposed method could achieve rapid fault detection and the localization of multi-sensor faults in PMTDS and had a good application value.
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