3,637 research outputs found

    Distributed feedback control on the SIS network model:An impossibility result

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    This paper considers the deterministic Susceptible-Infected-Susceptible (SIS) epidemic network model, over strongly connected networks. It is well known that there exists an endemic equilibrium (the disease persists in all nodes of the network) if and only if the effective reproduction number of the network is greater than 1. In fact, the endemic equilibrium is unique and is asymptotically stable for all feasible nonzero initial conditions. We consider the recovery rate of each node as a control input. Using results from differential topology and monotone systems, we establish that it is impossible for a large class of distributed feedback controllers to drive the network to the healthy equilibrium (where every node is disease free) if the uncontrolled network has a reproduction number greater than 1. In fact, a unique endemic equilibrium exists in the controlled network, and it is exponentially stable for all feasible nonzero initial conditions. We illustrate our impossibility result using simulations, and discuss the implications on the problem of control over epidemic networks. </p

    A network SIS meta-population model with transportation flow

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    This paper considers a deterministic Susceptible-Infected-Susceptible (SIS) metapopulation model for the spread of a disease in a strongly connected network, where each node represents a large population. Individuals can travel between the nodes (populations). We derive a necessary and sufficient condition for the healthy equilibrium to be the unique equilibrium of the system, and then in fact it is asymptotically stable for all initial conditions (a sufficient condition for exponential stability is also given). If the condition is not satisfied, then there additionally exists a unique endemic equilibrium which is exponentially stable for all nonzero initial conditions. We then consider time-delay in the travel between nodes, and further investigate the role of the mobility rate that governs the flow of individuals between nodes in determining the convergence properties. We find that sometimes, increasing mobility helps the system converge to the healthy equilibrium.</p

    Acceleration of on-axis and ring-shaped electron beams in wakefields driven by Laguerre-Gaussian pulses

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    The acceleration of electron beams with multiple transverse structures in wakefields driven by Laguerre-Gaussian pulses has been studied through three-dimensional (3D) particle-in-cell simulations. Under different laser-plasma conditions, the wakefield shows different transverse structures. In general cases, the wakefield shows a donut-like structure and it accelerates the ring-shaped hollow electron beam. When a lower plasma density or a smaller laser spot size is used, besides the donut-like wakefield, a central bell-like wakefield can also be excited. The wake sets in the center of the donut-like wake. In this case, both a central on-axis electron beam and a ring-shaped electron beam are simultaneously accelerated. Further, reducing the plasma density or laser spot size leads to an on-axis electron beam acceleration only. The research is beneficial for some potential applications requiring special pulse beam structures, such as positron acceleration and collimation

    mPLUG-Owl2: Revolutionizing Multi-modal Large Language Model with Modality Collaboration

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    Multi-modal Large Language Models (MLLMs) have demonstrated impressive instruction abilities across various open-ended tasks. However, previous methods primarily focus on enhancing multi-modal capabilities. In this work, we introduce a versatile multi-modal large language model, mPLUG-Owl2, which effectively leverages modality collaboration to improve performance in both text and multi-modal tasks. mPLUG-Owl2 utilizes a modularized network design, with the language decoder acting as a universal interface for managing different modalities. Specifically, mPLUG-Owl2 incorporates shared functional modules to facilitate modality collaboration and introduces a modality-adaptive module that preserves modality-specific features. Extensive experiments reveal that mPLUG-Owl2 is capable of generalizing both text tasks and multi-modal tasks and achieving state-of-the-art performances with a single generic model. Notably, mPLUG-Owl2 is the first MLLM model that demonstrates the modality collaboration phenomenon in both pure-text and multi-modal scenarios, setting a pioneering path in the development of future multi-modal foundation models

    Numerical analysis of solid liquid two phase abrasive flow polishing process for three stage variable diameter pipe

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    With the rapid development of technology and economy, rough machining has not been able to keep pace with the times. Heavy industry is more and more inclined to the field of precision and ultra-precision machining. During that time, abrasive flow machining technology emerged as the times require. The process of micro cutting is achieved through the contact between abrasive particles and workpiece, so that the accuracy of workpiece's inner surface can be polished, and the accuracy of workpiece improved, which is a representative polishing method. Taking the three-order variable diameter tube as the research object, this paper discusses the polishing characteristics of three level variable diameter pipe with solid liquid two phase abrasive flow. The removal pattern of abrasive flow micro cutting is analyzed, with the collision effect between abrasive particles and wall considered and ignored, which provides technical support for abrasive flow polishing variable diameter pipe parts

    126例肠道病毒71型和柯萨奇A组共感的临床特征分析*

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    Objective: To explore the attack, prevalence, clinical features, diagnosis, therapy and prognosis of enterovirus 71 and coxsackie A16. Methods: Analyzing the general situation, main symptoms and signs, laboratory examination, virus effect analysis and the prognosis of 126 cases of hospital medical records. Results: Among the 126 cases, CA16 is in the majority, and EV71 virus is coexisting. Besides, the ordinary cases have mild symptoms without serious complications, and attention should be paid attention to the fever, blood glucose and myocardial enzyme spectrum and complications, etc. Severe cases need to be discovered early. Conclusion: Timely detection and treatment are the effective ways to reduce the deaths of seriously ill patients lie in full attention to the severe trend.目的  探讨肠道病毒71型(EV71)和柯萨奇A组16型(CoxA16)共感的发病、流行及临床特征、诊断、治疗及预后。方法  分析126例住院病历的一般情况,主要症状及体征,实验室检查,病毒分析情况及治疗预后效果。结果  126例病例中,以CA16为主,有EV71病毒同时存在,普通病例症状轻,无严重并发症,要注意发热、血糖、心肌酶谱及合并症等。尽早发现重症病例。结论  充分重视重症趋势,及时发现,及时治疗,是目前减少重症患者死亡的有效方法

    Numerical simulation analysis of multi-physical coupling field with abrasive flow precision polishing variable-aperture tube

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    In the fields of aerospace, precision machinery and energy, there are variable-diameter tubes for many key components. Abrasive flow polishing technology is an effective precision polishing technology for finishing the workpiece with an internal cavity structure. This technology can improve the quality of part finishing, reduce stress concentration, and reduce the surface roughness of the workpiece, and ultimately can improve the performance of the workpiece. In this paper, variable-aperture tube is taken as the research object, and the characteristics of abrasive flow in the multi-physics coupling field are studied by numerical simulation, and the collision removal effect between the abrasive particle and the wall surface is analyzed. We also discussed the control law of the abrasive grain flow processing quality and provided theoretical guidance for abrasive grain flow polishing of this type of part
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