A stochastic model of the influence of buffer gas collisions on Mollow spectra

In this paper we consider the influence of collisional fluctuations on the Mollow spectra of resonance fluorescence (RF). The fluctuations are taken into account by a simple shift of the constant detuning, involved in a set of optical Bloch equations by collision frequency noise which is modelled by a two-step random telegraph signal (RTS). We consider in detail the Mollow spectra for RF in the case of an arbitrary detuning of the laser frequency, where the emitter is a member of a statistical ensemble in thermodynamic equilibrium with the buffer gas at temperature $T$ which is treated as a colored environment, and velocity $v$ is distributed with the Maxwell-Boltzmann density

APMEC: An Automated Provisioning Framework for Multi-access Edge Computing

Novel use cases and verticals such as connected cars and human-robot cooperation in the areas of 5G and Tactile Internet can significantly benefit from the flexibility and reduced latency provided by Network Function Virtualization (NFV) and Multi-Access Edge Computing (MEC). Existing frameworks managing and orchestrating MEC and NFV are either tightly coupled or completely separated. The former design is inflexible and increases the complexity of one framework. Whereas, the latter leads to inefficient use of computation resources because information are not shared. We introduce APMEC, a dedicated framework for MEC while enabling the collaboration with the management and orchestration (MANO) frameworks for NFV. The new design allows to reuse allocated network services, thus maximizing resource utilization. Measurement results have shown that APMEC can allocate up to 60% more number of network services. Being developed on top of OpenStack, APMEC is an open source project, available for collaboration and facilitating further research activities

Defective hierarchical porous copper-based metal-organic frameworks synthesised via facile acid etching strategy

Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a dilute solvent. Interestingly, we demonstrate that the etching process which is time- and acidity- dependent, can result in formation of defective HKUST-1 with extra interconnected hexagonal macropores without compromising on the bulk crystallinity. These findings suggest an intelligent scalable synthetic method for formation of hierarchical porosity in MOFs that are prone to hydrolysis, for improved molecular accessibility and diffusion for catalysis.Comment: 14 pages, 8 figure

Form and Function: X-Ray Scattering and Spectroscopy of Transition Metal-Based Nanoparticles

In recent decades, nanoparticles have been found to possess unique, tunable properties with an enormous variety of applications. The atomic and nanoscale structures govern these functional properties, and structural deviations from the bulk, in part, are responsible for the vast technological uses of nanoparticles. This dissertation tackles the understanding of structure in a number of metal, metal phosphide, and metal oxide nanoparticle systems. Additionally, the syntheses of monodispersed nanoparticle systems allow for correlating their structure with functional properties. Real space analysis using pair distribution functions of monometallic (Ni, Pd) nanoparticles of less than 5 nm in diameter revealed a deviation from the bulk face-centered cubic structure. Their local atomic packing disorder and lack of long-range order resemble that of bulk metallic glasses, which often consist of complex mixtures of a multitude of elements. Bulk metallic glasses have high mechanical strength and can sustain elastic deformations. The significant connection between these two seemingly disparate systems lie in the short-range ordering of their atomic packing motifs, which consist of icosahedral symmetry as seen in their pair distribution functions. Cobalt phosphide (Co2P) nanorods are promising as inexpensive, earth abundant catalysts for the oxygen reduction reaction in fuel cells. Additionally, their 1-D structures demonstrated greater stability as compared to conventional Pt catalysts. Their structure was investigated using high-resolution electron microscopy and a suite of X-ray scattering and absorption techniques. The dynamic structural nature of the solid-solid phase transition in vanadium dioxide (VO2) thin films was investigated using X-ray absorption fine structure spectroscopy. Substitution of transition metal dopants into lattice sites revealed the structurally-driven depression of the metal-to-insulator transition temperature. Bridging form and function, this dissertation reports the colloidal synthesis of monodispersed nanoparticles alongside structural investigations and functional testing

Distributed two-time-scale methods over clustered networks

In this paper, we consider consensus problems over a network of nodes, where the network is divided into a number of clusters. We are interested in the case where the communication topology within each cluster is dense as compared to the sparse communication across the clusters. Moreover, each cluster has one leader which can communicate with other leaders in different clusters. The goal of the nodes is to agree at some common value under the presence of communication delays across the clusters. Our main contribution is to propose a novel distributed two-time-scale consensus algorithm, which pertains to the separation in network topology of clustered networks. In particular, one scale is to model the dynamic of the agents in each cluster, which is much faster (due to the dense communication) than the scale describing the slowly aggregated evolution between the clusters (due to the sparse communication). We prove the convergence of the proposed method in the presence of uniform, but possibly arbitrarily large, communication delays between the leaders. In addition, we provided an explicit formula for the convergence rate of such algorithm, which characterizes the impact of delays and the network topology. Our results shows that after a transient time characterized by the topology of each cluster, the convergence of the two-time-scale consensus method only depends on the connectivity of the leaders. Finally, we validate our theoretical results by a number of numerical simulations on different clustered networks

Braking and Body Angles Control of an Insect-Computer Hybrid Robot by Electrical Stimulation of Beetle Flight Muscle in Free Flight

While engineers put lots of effort, resources, and time in building insect scale micro aerial vehicles (MAVs) that fly like insects, insects themselves are the real masters of flight. What if we would use living insect as platform for MAV instead? Here, we reported a flight control via electrical stimulation of a flight muscle of an insect-computer hybrid robot, which is the interface of a mountable wireless backpack controller and a living beetle. The beetle uses indirect flight muscles to drive wing flapping and three major direct flight muscles (basalar, subalar and third axilliary (3Ax) muscles) to control the kinematics of the wings for flight maneuver. While turning control was already achieved by stimulating basalar and 3Ax muscles, electrical stimulation of subalar muscles resulted in braking and elevation control in flight. We also demonstrated around 20 degrees of contralateral yaw and roll by stimulating individual subalar muscle. Stimulating both subalar muscles lead to an increase of 20 degrees in pitch and decelerate the flight by 1.5 m/s2 as well as an induce an elevation of 2 m/s2.Comment: 9 pages, 7 figures, supplemental video: https://youtu.be/P9dxsSf14LY . Cyborg and Bionic Systems 202