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الأجراس الذهبية
في قرية فاولا وتشوانغ أراد السيد قاو العثور على زوج لابنته الصغرى ولكن الأمر انتهى به الشيطان الخنزير ودعا السيد قاو الكثيرين لإخضاع الشيطان لكنهم فشلوا. وعندما سمع سان تسائخ والقرد أثناء رحلتهما إلى الغرب أن هناك شيطانا في القرية، تطوع الفرد للمساعدة، والتقى بالشيطان الخنزير وحاربه ولحق به إلى كيفه. أدرك الشيطان الخنزير أن سان تسانغ والقرد في رحلة لإحضار الكتب المقدسة، فأخبر القرد أنه كان ينتظرهما بعدما تلقى تعليمات من قوان بن. لكن القرد لم يصدقه فطلب منه أن يحرق كهفه ثم سيأخذه لمقابلة سان تسانغ فك سان تسانغ وثاق الشيطان الخنزير واتخذه تلميذا ثانيا له. واتضح أن الشيطان الخنزير كان قائدا في السماء ولكنه نفي إلى العالم الأرضي لسوء سلوكه، ومنحته قوان بن اسم وو ننغ ثم منحه سان تسانغ اسم \"با جیه\".
Book
Dynamic event-triggered delay compensation control for networked predictive control systems with random delay
This paper aims to investigate the dynamic event-triggered control problem for networked predictive control systems with random delays and disturbance. First, a discrete-time dynamic event-triggered control scheme, in which sensor information is only updated when it is necessary, is presented. Next, the systems are modeled as a time-delay singular Markovian jump systems with time-varying switching. Then, a dynamic event-triggered delay compensation control strategy is proposed. Sufficient conditions guaranteeing the asymptotically stable are derived based on the Lyapunov–Krasovskii functional method together with the linear matrix inequality (LMI) technique. Finally, simulation results verify the effectiveness of the proposed strategy.
Journal Article
Low-drift and real-time lidar odometry and mapping
Here we propose a real-time method for low-drift odometry and mapping using range measurements from a 3D laser scanner moving in 6-DOF. The problem is hard because the range measurements are received at different times, and errors in motion estimation (especially without an external reference such as GPS) cause mis-registration of the resulting point cloud. To date, coherent 3D maps have been built by off-line batch methods, often using loop closure to correct for drift over time. Our method achieves both low-drift in motion estimation and low-computational complexity. The key idea that makes this level of performance possible is the division of the complex problem of Simultaneous Localization and Mapping, which seeks to optimize a large number of variables simultaneously, into two algorithms. One algorithm performs odometry at a high-frequency but at low fidelity to estimate velocity of the laser scanner. Although not necessary, if an IMU is available, it can provide a motion prior and mitigate for gross, high-frequency motion. A second algorithm runs at an order of magnitude lower frequency for fine matching and registration of the point cloud. Combination of the two algorithms allows map creation in real-time. Our method has been evaluated by indoor and outdoor experiments as well as the KITTI odometry benchmark. The results indicate that the proposed method can achieve accuracy comparable to the state of the art offline, batch methods.
Journal Article
Intragranular cracking as a critical barrier for high-voltage usage of layer-structured cathode for lithium-ion batteries
LiNi
1/3
Mn
1/3
Co
1/3
O
2
-layered cathode is often fabricated in the form of secondary particles, consisting of densely packed primary particles. This offers advantages for high energy density and alleviation of cathode side reactions/corrosions, but introduces drawbacks such as intergranular cracking. Here, we report unexpected observations on the nucleation and growth of intragranular cracks in a commercial LiNi
1/3
Mn
1/3
Co
1/3
O
2
cathode by using advanced scanning transmission electron microscopy. We find the formation of the intragranular cracks is directly associated with high-voltage cycling, an electrochemically driven and diffusion-controlled process. The intragranular cracks are noticed to be characteristically initiated from the grain interior, a consequence of a dislocation-based crack incubation mechanism. This observation is in sharp contrast with general theoretical models, predicting the initiation of intragranular cracks from grain boundaries or particle surfaces. Our study emphasizes that maintaining structural stability is the key step towards high-voltage operation of layered-cathode materials.
Cycling-induced fracture can limit conditions for stable operation for various lithium-ion electrode materials. Here, the authors characterize fracture in nickel-manganese-cobalt oxide microscopically and provide evidence for dislocation-assisted, intragranular fracture operating above a critical voltage threshold.
Journal Article
Injection of oxygen vacancies in the bulk lattice of layered cathodes
Surfaces, interfaces and grain boundaries are classically known to be sinks of defects generated within the bulk lattice. Here, we report an inverse case by which the defects generated at the particle surface are continuously pumped into the bulk lattice. We show that, during operation of a rechargeable battery, oxygen vacancies produced at the surfaces of lithium-rich layered cathode particles migrate towards the inside lattice. This process is associated with a high cutoff voltage at which an anionic redox process is activated. First-principle calculations reveal that triggering of this redox process leads to a sharp decrease of both the formation energy of oxygen vacancies and the migration barrier of oxidized oxide ions, therefore enabling the migration of oxygen vacancies into the bulk lattice of the cathode. This work unveils a coupled redox dynamic that needs to be taken into account when designing high-capacity layered cathode materials for high-voltage lithium-ion batteries.Lithium transition metal oxide cathodes can degrade under high-voltage conditions by a redox mechanism by which oxygen vacancies form at the surface and migrate towards the bulk.
Journal Article
Progressive growth of the solid–electrolyte interphase towards the Si anode interior causes capacity fading
The solid–electrolyte interphase (SEI), a layer formed on the electrode surface, is essential for electrochemical reactions in batteries and critically governs the battery stability. Active materials, especially those with extremely high energy density, such as silicon (Si), often inevitably undergo a large volume swing upon ion insertion and extraction, raising a critical question as to how the SEI interactively responds to and evolves with the material and consequently controls the cycling stability of the battery. Here, by integrating sensitive elemental tomography, an advanced algorithm and cryogenic scanning transmission electron microscopy, we unveil, in three dimensions, a correlated structural and chemical evolution of Si and SEI. Corroborated with a chemomechanical model, we demonstrate progressive electrolyte permeation and SEI growth along the percolation channel of the nanovoids due to vacancy injection and condensation during the delithiation process. Consequently, the Si–SEI spatial configuration evolves from the classic ‘core–shell’ structure in the first few cycles to a ‘plum-pudding’ structure following extended cycling, featuring the engulfing of Si domains by the SEI, which leads to the disruption of electron conduction pathways and formation of dead Si, contributing to capacity loss. The spatially coupled interactive evolution model of SEI and active materials, in principle, applies to a broad class of high-capacity electrode materials, leading to a critical insight for remedying the fading of high-capacity electrodes.
A correlated structural and chemical evolution of silicon and the solid–electrolyte interphase was unveiled in three dimensions by integrating sensitive elemental tomography, an advanced algorithm and cryogenic scanning transmission electron microscopy.
Journal Article