730 research outputs found

    Infinite randomness and quantum Griffiths effects in a classical system: the randomly layered Heisenberg magnet

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    We investigate the phase transition in a three-dimensional classical Heisenberg magnet with planar defects, i.e., disorder perfectly correlated in two dimensions. By applying a strong-disorder renormalization group, we show that the critical point has exotic infinite-randomness character. It is accompanied by strong power-law Griffiths singularities. We compute various thermodynamic observables paying particular attention to finite-size effects relevant for an experimental verification of our theory. We also study the critical dynamics within a Langevin equation approach and find it extremely slow. At the critical point, the autocorrelation function decays only logarithmically with time while it follows a nonuniversal power-law in the Griffiths phase.Comment: 10 pages, 2 eps figures included, final version as published

    AUTHENTICATION AND KEY MANAGEMENT OF IOT APPLICATIONS WITH EXTENDED WIFI AUTHENTICATION (WIFI AKMA)

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    Internet of things (IoT) devices frequently apply insufficient authentication mechanisms with their application servers due to the constrained nature of such devices. For example, most IoT devices lack the resources that are necessary to store usernames and passwords, certificates, and keys in a secured manner. The challenge that was described above is solved in a 3rd Generation Partnership Project (3GPP) fifth-generation (5G) wireless environment through the Authentication and Key Management for Applications (AKMA) initiative. However, there is no AKMA-equivalent facility within a WiFi environment. Accordingly, techniques are presented herein that extend the WiFi authentication process to support application server authentication for constrained devices. Aspects of the presented techniques support an exchange of a WiFi key and a key identifier (which may be referred to herein as a KAKMA key and an A-KID) as part of an Extensible Authentication Protocol (EAP) tunnel using a new information element (IE) once an authentication process has successfully completed. Such an exchange allows a station (STA) device to use the key tuple {KAKMA, A-KID} to access any application functions that are grouped with that key identifier (i.e., A-KID) without requiring any further authentication

    PRIORITY ROUTING OF SHIPMENT USING IOT SENSOR DATA FROM SHIPMENT PACKAGES

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    Techniques are provided to prioritize shipping containers using sensor data by monitoring the health of the package being shipped. Based on smart contract terms, the priority of the shipment is dynamically elevated and the package is shipped faster

    Dynamic Analysis and Modeling of Jansen Mechanism

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    AbstractTheo Jansen mechanism is gaining wide spread popularity among legged robotics researchers due to its scalable design, energy efficiency, low payload to machine load ratio, bio-inspired locomotion, deterministic foot trajectory among others. In this paper, we present dynamic analysis of a four legged Theo Jansen link mechanism using projection method that results in constraint force and equivalent Lagrange's equation of motion necessary for any meaningful extension and/or optimization of this niche mechanism. Numerical simulations using MaTX is presented in conjunction with the dynamic analysis. This research sets a theoretical basis for future investigation into Theo Jansen mechanism

    Rolling Locomotion Control of a Biologically Inspired Quadruped Robot Based on Energy Compensation

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    We have developed a biologically inspired reconfigurable quadruped robot which can perform walking and rolling locomotion and transform between walking and rolling by reconfiguring its legs. This paper presents an approach to control rolling locomotion with the biologically inspired quadruped robot. For controlling rolling locomotion, a controller which can compensate robot’s energy loss during rolling locomotion is designed based on a dynamic model of the quadruped robot. The dynamic model describes planar rolling locomotion based on an assumption that the quadruped robot does not fall down while rolling and the influences of collision and contact with the ground, and it is applied for computing the mechanical energy and a plant in a numerical simulation. The numerical simulation of rolling locomotion on the flat ground verifies the effectiveness of the proposed controller. The simulation results show that the quadruped robot can perform periodic rolling locomotion with the proposed energy-based controller. In conclusion, it is shown that the proposed control approach is effective in achieving the periodic rolling locomotion on the flat ground

    PROACTIVE EXCHANGE OF DATA BETWEEN CLOUD PROVIDERS VIA CONTROLLER COORDINATION AND TRIGGER DYNAMIC WORKFLOWS

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    A multi-cloud Software Defined Network (SDN) controller proactively learns insights about subscribers, such as enterprise users, end users, and/or other cloud providers. Based on the learned insights, the multi-SDN controller applies dynamic policies on other cloud provides to which those subscribers are attached to. The multi-cloud SDN controller co-ordinates with various cloud providers, enterprise network controllers, and Internet Service Providers (ISPs) to proactively notify other cloud providers with information about affected users so that those providers can install additional resources at cloud edge/core on the fly. Additionally, the multi-cloud SDN controller facilitates a warm hand off from one cloud region to another cloud region. When the multi-cloud SDN controller learns about an enterprise outage, it proactively notifies other cloud providers of the outage event and the other cloud providers can use this for a warm hand off of session to the region(s) through which the users will be reconnected. The likely regions are derived based on telemetry obtained from multi-cloud SDN controller. The multi-cloud SDN controller also triggers a proactive cleanup of user context of the cloud provider side. The cloud provider cleans up after the connection reset event based on information from the multi-cloud SDN controller, rather than wait on a timeout of the connection
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