A Stochastic Approach to Shortcut Bridging in Programmable Matter

In a self-organizing particle system, an abstraction of programmable matter, simple computational elements called particles with limited memory and communication self-organize to solve system-wide problems of movement, coordination, and configuration. In this paper, we consider a stochastic, distributed, local, asynchronous algorithm for "shortcut bridging", in which particles self-assemble bridges over gaps that simultaneously balance minimizing the length and cost of the bridge. Army ants of the genus Eciton have been observed exhibiting a similar behavior in their foraging trails, dynamically adjusting their bridges to satisfy an efficiency trade-off using local interactions. Using techniques from Markov chain analysis, we rigorously analyze our algorithm, show it achieves a near-optimal balance between the competing factors of path length and bridge cost, and prove that it exhibits a dependence on the angle of the gap being "shortcut" similar to that of the ant bridges. We also present simulation results that qualitatively compare our algorithm with the army ant bridging behavior. Our work gives a plausible explanation of how convergence to globally optimal configurations can be achieved via local interactions by simple organisms (e.g., ants) with some limited computational power and access to random bits. The proposed algorithm also demonstrates the robustness of the stochastic approach to algorithms for programmable matter, as it is a surprisingly simple extension of our previous stochastic algorithm for compression.Comment: Published in Proc. of DNA23: DNA Computing and Molecular Programming - 23rd International Conference, 2017. An updated journal version will appear in the DNA23 Special Issue of Natural Computin

Autologous cricoid cartilage as a graft for airway reconstruction in an emergent technique - A case report

Introduction: Laryngotracheal stenosis can be caused after traumatic injuries to the neck from the subglottic larynx to the trachea. Patients with laryngotracheal stenosis often need a tracheotomy and occasionally may become tracheotomy dependent. Different procedures have been described for the management of these lesions. Management options include techniques of endoscopic dilation, laser resection, laryngo-fissure, and an innovative array of plastic reconstructions with or without the use of stents. Case Report: This paper presents airway reconstruction in a young patient with severe subglottic stenosis due to a blunt trauma to the neck, who was treated using particles of an autologous fractured cricoid cartilage as the source for airway augmentation. An incision was made in the anterior midline of the cricoid lamina and deepened through the scar tissue to the posterior cricoid lamina. Then two lateral incisions (right&left) were made in the cricoid lamina and fractured cartilage particles and the scar tissue were removed via these two lateral incisions. The mucosal lining at the right and left of the midline incision, after debulking, were sutured to a lateral position. Thereafter three cartilage particles were used to reconstruct the anterior cricoid lamina and augment the lumen. Conclusion: It is worth to mention that an autologus cartilage graft can be used for certain cases with traumatic airway stenosis. Further follow up and more patients are needed to approve this method of reconstructive surgery in emergent situations

The shear viscosity of carbon fibre suspension and its application for fibre length measurement

The viscosity of short carbon fibre suspensions in glycerol aqueous solution was measured using a bespoke vane-in-cup viscometer, where the carbon fibre has an aspect ratio from 450 to 2209. In the semi-concentrated regime, nL3 ranging from 20 to 4400, the suspensions demonstrated strong shear-thinning characteristics particularly at higher concentrations. The shear-thinning characteristic is strongly related to the crowding factor proposed by Kerekes, indicating that non-hydrodynamic interactions occur in the suspensions. The influence of fibre bending on viscosity emerges when the bending ratio is lower than 0.0028. An empirical model based on transient network formation and rupture was proposed and used to correlate the relative viscosity with fibre concentration nL3 and shear rate. Based on the model, a viscosity method is established to analyse the fibre length by measuring the viscosity of the fibre suspension using a bespoke vane-in-cup viscometer

Disposable sensors in diagnostics, food and environmental monitoring

Disposable sensors are low‐cost and easy‐to‐use sensing devices intended for short‐term or rapid single‐point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource‐limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo‐ and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low‐cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities

Flow-induced vibration of an elastically mounted airfoil under the influence of the wake of a circular cylinder

Abstract not availableJ.F. Derakhshandeh, M. Arjomandi, B. Dally, B. Cazzolat

The effect of arrangement of two circular cylinders on the maximum efficiency of Vortex-Induced Vibration power using a Scale-Adaptive Simulation model

Abstract not availableJavad Farrokhi Derakhshandeh, Maziar Arjomandi, Bassam Dally, Benjamin Cazzolat

Effect of a rigid wall on the vortex induced vibration of two staggered circular cylinders

Abstract not availableJavad Farrokhi Derakhshandeh, Maziar Arjomandi, Benjamin S. Cazzolato, and Bassam Dall

Numerical simulation of vortex-induced vibration of elastic cylinder

Study of the flow around a bluff body and its effect on the flow induced vibration is relevant to design of bridges, tall buildings and similar structures. The flow around bluff bodies, arranged in tandem where one of the bodies is in the wake region of the seconds one, was studied using numerical simulation. This phenomenon is related to the response of bluff bodies immersed in fluid flow and is known as Vortex Induced Vibration (VIV). Vortex energy extraction is of interest to this work. This paper presents the results of a 2D numerical simulation of the wake interaction of two circular cylinders at low Reynolds number using ANSYS Fluent Workbench. The upstream cylinder is stationary, while the downstream elastic cylinder can be affected by the vortices in the wake of the first cylinder. The paper reports the behaviour of the elastic cylinder through a CFD model, with a focus on harnessing the vortical energy. Also discussed is the theoretical maximum energy that can be harvested by this method. For validation purposes, the modelled amplitude of the oscillation is compared to published data in literature. The results show that the motion of elastic cylinder can be modelled as a simple mass spring damper model.Javad Farrokhi Derakhshandeh, Maziar Arjomandi, Benjamin Cazzolato and Bassam Dallyhttp://www.afms.org.au/conference/18%20AFMC%20TOC.ht

Harnessing hydro-kinetic energy from wake-induced vibration using virtual mass spring damper system

Abstract not availableJ.F. Derakhshandeh, M. Arjomandi, B.S. Cazzolato, B. Dall