Abstract: Biological intelligence, which includes features such as perception, memory, learning, problem-solving and decision-making, is widely observed in humans, animals and other higher organisms with nervous systems. Recent studies have shown that single cells also exhibit behaviours that resemble human-like intelligence in their interactions with the microenvironment, such as “multimodal perception”, “problem solving”, “learning and memory”, and “evolutionary adaptation”. Cellular intelligence, as a newly proposed and disruptive theoretical concept, raises fundamental questions, including the principles underlying the emergence of cellular intelligence, the mechanisms by which collective cell behaviour emerges as collective intelligence, and the evolutionary drivers for single cells to evolve into multicellular life forms. As the fields of biomechanics and mechanobiology have advanced, numerous studies have demonstrated the significant influence of the mechanical microenvironment on cellular physiological behaviour. Under mechanical stimulation, even single cells exhibit intelligent behaviours similar to those observed in higher organisms. Based on this, the concept of “cellular mechanical intelligence” is proposed in this paper. We summarise the characteristics of intelligent behaviours in terms of mechanical perception, mechanical decision making, mechanical memory and mechanical learning, with the aim of providing new insights and perspectives on the mechanisms underlying cellular mechanical intelligence and its potential applications, such as in cellular intelligent medicine.
Cheng B, Lu M N, Jia Y B, Xu F. Cellular Mechanical Intelligence. AdvancesinMechanics, in press. doi: 10.6052/1000-0992-24-028.
Abstract: On-orbit assembly of ultra-large space structures serves as the technological foundation for future space missions including high-capacity space-based communications, high-precision space-based observations and space-based solar power stations. It holds significant scientific and engineering values. Addressing the demands for assembling ultra-large structures like 100-meter parabolic antennas on orbit, this review article surveys the research progress and challenges in the dynamics and control of ultra-large space structures assembled on orbit. The article focuses on five key aspects, including the overall assembly design and its dynamic problems, the dynamic modeling and computation of flexible multibody systems, the motion planning and control of robots, the dynamic verification and adjustment of assembly outcomes, and the ground simulation experiments. It highlights the necessity of solving critical issues such as the multi-scaled spatiotemporal coupling dynamics of flexible components undergoing large overall motions, the efficient motion planning and accurate control method of robots, and the thermal-mechanically coupled error verification and adjustment strategies. As such, the necessity requires a comprehensive research framework integrating theoretical analysis, numerical simulation, and ground experimental validation to realize the ultra-large space structures in a scale from 100 meters to 1000 meters. Finally, the article outlines research priorities for the next decade, including the efficient dynamics modeling, the motion planning and control of robots in complex environments, the dynamic prediction and adjustment of multi-module closed-loop assembly, and the earth-space consistent experiment validation systems, providing systematic suggestions for promoting the on-orbit assembly technology of ultra-large space structures.
Hu H Y, Tian Q, Wen H, Luo K, Ma X F. Dynamics and Control of On-Orbit Assembly of Ultra-Large Space Structures. AdvancesinMechanics, in press. doi: 10.6052/1000-0992-24-044.
Abstract: Direct time integration methods play a critical role in the numerical computation of large-scale nonlinear dynamic systems, particularly in the field of engineering simulation and design. The self-starting single-solve explicit time integration methods have become essential tools in this domain due to their efficiency and reliability in handling complex nonlinear systems. However, as these algorithms continue to evolve and diversify, their performance varies significantly, underscoring the urgent need for a systematic review and in-depth analysis of their capabilities. This paper first introduces the key performance metrics for evaluating time integration methods, including accuracy, stability, amplitude and phase error, providing a theoretical foundation for readers. It then offers a detailed review of the development of self-starting single-solve explicit time integration methods, systematically tracing the evolution of various algorithms. Finally, the performance of several self-starting single-solve explicit methods is compared in terms of spectral properties, accuracy, stability, and error characteristics, with numerical verification performed using typical examples and engineering structures. The paper highlights two explicit methods that currently exhibit superior performance: the fully explicit GSSE method and the velocity-implicit GSSI method. Both methods are characterized by their self-starting capability, single-solution, explicitness, maximized conditional stability, controllable numerical dissipation (over the full range), and identical second-order accuracy. The primary distinction between the two lies in the computational effort required for damping problems and the size of the conditional stability domain in the presence of damping. The paper also explores future research directions for explicit time integration methods, emphasizing the potential for further optimization and development.
Li J Z, Liu Y K, Yu K P, Cui N G. Research progress and performance evaluations for self-starting single-solve explicit time integrators. AdvancesinMechanics, in press. doi: 10.6052/1000-0992-24-030.
Abstract: This paper is intended to reconcile the stress-based and strain-based formulations for material failure criteria, where a longstanding and deep division is present. The two approaches do not naturally agree with each other, and they not genuinely complement each other, either. Most popular criteria are stress-based when originally proposed, including the maximum stress, Tresca, von Mises, Raghava-Caddell-Yeh and the Mohr criteria. Their formulations are unique and self-consistent, i.e. capable of reproducing the input data. Their strain-based counterparts, with the maximum strain criterion being considered as the strain-based counterpart of the maximum stress criterion, are neither unique nor necessarily self-consistent. It has been proven that the self-consistent ones reproduce their respective stress-based counterparts identically in effect with a disadvantage of requiring an additional material property to apply, without a single benefit. For the Mohr criterion as a special case, a strain-based counterpart is simply infeasible in general. All undesirable features of strain-based criteria are rooted in a single source: the failure strains can only be measured under a uniaxial stress state, which corresponds to a combined strain state in general, not a uniaxial strain state! Given the arguments presented, the reconciliation proves to be biased completely towards the stress-based side if mathematics, logic and common sense prevail over perception and prejudice.
Li S G. Stress or Strain?. AdvancesinMechanics, in press. doi: 10.6052/1000-0992-24-035.
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