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A Wideband Blocker-Tolerant Receiver With Frequency-Translational Resistive Feedback (vol 27, pg 993, 2019)
No full textData-driven and GIS-based Coverage Estimation in a Heterogeneous Propagation Environment
No full textWe provide a data-driven coverage estimation technique that employs machine-learning based regression ideas for exploiting commonality of antenna-gain and other parameters across measurements made in multiple propagation environments. We then show how readily available geographic information system (GIS) data could be exploited for quick classification of geographic areas into various propagation environments, and how this could enable quick and automated estimation of coverage for faster and more efficient deployment of Internet of Things
Thermodynamic properties of Pr7O12
No full textTo explore the potential of Pr7O12 in a biphasic oxygen buffer in automobile exhaust control systems, thermodynamic data for Pr7O12 are required. Since there is no information on Pr7O12 in thermodynamic data compilations, its Gibbs energy of formation has been determined relative to that of Pr2O3 as a function of temperature in the range from 850 to 1200 K using a solid-state electrochemical technique. The standard molar Gibbs energy of formation of Pr7O12 from elements can be represented by two equations. In the range from 850 to 1068 K, Delta G(f)degrees (J mol(-1)) = -6454317 + 1085.52 (T/K). From 1068 to 1204 K, Delta G(f)degrees (J mol(-1)) = -6467695 + 1097.77 (T/K)
Crowdsourcing-based traffic simulation for smart freight mobility
No full textCrowdsourcing is emerging as a powerful tool in transportation applications as it aims to provides possible solutions to problems by soliciting inputs from the crowd - usually people, objects or entities on an individual level. The primary sources of `big data' in transportation (which includes social media, mobile applications and connected vehicles) facilitate this evolution through crowdsourcing; however, limited applications of crowdsourcing have been found in literature for the freight operations. In this paper, a simulation framework is developed combined with probabilistic modeling to make freight truck a `smart freight' truck -with improved mobility by being able to detour to avoid a downstream congestion on the path. Smart freight trucks have access to crowdsourced data on an imminent congestion on its route and can detour leveraging this privilege. A discrete-time Markov chain (DTMC)-based simulation model is developed which describes the detour process through the nearest exit ramp of a freeway. The detour occurs with the help of crowdsourced information on a downstream congestion location. Simulation analyses carried out with both average daily passenger cars and truck traffic volumes using interstate 405 (I-405) and I-605 in the Southern California Region substantiate the effectiveness of the model. Simulation analysis shows that the efficiency improvements in detouring freight trucks under free flow traffic conditions and congested scenarios are 52% and 31%, respectively. Since connected vehicle technology (CVT) relies heavily on crowdsourced information from other vehicles in the fleet, simulation findings of this research can have large-scale implications in determining the success of CVT applications in freight operations. This crowdsourced data-based simulation framework can be used within traffic simulation software packages to enhance both passenger and truck freight operations
Effect of chemical functionalization on charge transport of multiwall carbon nanotube
No full textWe have studied the effect of chemical functionalization on charge transport property of multiwall carbon nanotube (MWNT) down to the temperature 4.2 K and magnetic field up to 5 T. The resistivity ratio (rho(r) = rho(T)/rho(100 K)]) increases with the increment of degree of functionalization at low temperature as the effect of inclusion of disorder in the samples. The variation of resistivity with temperature has been explained by 3D variable range hopping model and Coulomb gap Efros-Shklovskii model, and the result shows that higher degree of functionalization enhances the disorder induced electron-electron interaction. For all the measured temperature and degree of functionalization, MWNTs show negative magnetoresistance. Negative magnetoresistance has been explained by 3D weak localization model
Pairing, waltzing and scattering of chemotactic active colloids
No full textWe study theoretically an active colloid whose polar axis of self-propulsion rotates to point parallel (antiparallel) to an imposed chemical gradient. We show that the coupling of this `chemotactic' ('antichemotactic') response to phoretic translational motion yields remarkable two-particle dynamics reflecting the non-central and non-reciprocal character of the interaction. A pair of mutually chemotactic colloids trap each other in a final state of fixed separation resulting in a selfpropelled active dieter. A second type of bound state is observed when the polar axes undergo periodic cycles leading to phase-locked circular motion around a common centre. A pair of swimmers with mismatched phoretic mobilities execute a dance in which they twirl around one another while moving jointly in a wide circle. For sufficiently small initial separation, the speed of self-propulsion controls the transition from bound to scattering states. Mutually anti-chemotactic swimmers always scatter apart. For the special case in which one of the two colloids has uniform surface activity we succeed in exactly classifying the fixed points underlying the bound states, and identify the bifurcations leading to transitions from one type of bound state to another. The varied dynamical behaviours are accessible by tuning the swimmer design and are summarised in state diagrams
An accelerometer balance for aerodynamic force measurements over Hypervelocity Ballistic models in shock tunnel
No full textA force balance to measure drag, lift and pitching moment over Hypervelocity Ballistic (HB) models 1 and 2 has been developed and assessed in an impulse test facility, hypersonic shock tunnel. The experiments were carried out at different angles of incidence of the models with the freestream at nominal Mach numbers of 5.78 and 8.31. The force balance is provided with rubber supports to ensure unrestrained motion of the model during the hypersonic freestream flow. Three dimensional finite element simulations are carried out to assess the performance of the force balance system in measuring the acceleration within the short test duration available in the shock tunnel. The force balance is mounted inside the model and is equipped with accelerometers to sense the model's acceleration in the desired direction. The aerodynamic force and moment coefficients are then deduced from the measured acceleration signals based on theories in aerodynamics. The measured values of force and moment coefficients match well with the theoretical values estimated using modified Newtonian theory for HB 1 and HB 2 models. In addition, CFD simulations are carried out for the experimental test cases using viscous, laminar models and the numerically computed force coefficients are validated by comparing against the experimental values. The present study demonstrates the use of accelerometer based force balance for measuring aerodynamic forces and moments over realistic long missile configurations
Comparative study of keratin extraction from human hair
No full textKeratin has been attracting interest due to its stability against enzymatic degradation thereby allowing more predictable degradation profile for tissue regeneration applications. While the efficacy of keratin has been demonstrated in different tissue models, there has been no systematic study to investigate and compare the different routes of keratin extraction from human hair. Here, we compared the four commonly used extraction methods and highlighted both physical and chemical differences in the extracted keratin. Keratin was extracted from human hair using one of four common agents, namely, sodium sulfide, peracetic acid, urea and thioglycolic add. Whereas no specific trend was observed, the keratin extracted through peracetic acid method had significantly different properties. It resulted in lowest yield of 52 mu g/mL and low crystallinity but the protein formed aggregates with highest hydrodynamic average size of around 283 nm compared to the other three methods. However, despite greater aggregation, keratin extracted from peracetic acid method exhibited secondary structural conformation similar to thioglycolic acid method. All the four extracted keratin promoted cellular proliferation of osteoblasts compared to the uncoated surface. These results provide new insight into the extraction of keratin from human hair with implications for its use as a biomaterial
High Pressure Tube Twisting for Producing Ultra Fine Grained Materials: A Review
No full textThe High Pressure Tube Twisting (HPTT) process was first proposed in 2009 as an efficient new Severe Plastic Deformation (SPD) process. Since then it has been successfully applied on many different materials and the results have been reported in several publications and thesis works. The purpose of this overview is to present and evaluate the main results of the published papers and thesis works and also to present new contributions. Special attention is given to the strain gradient which appears in the tube wall for which a new empirical formula is presented
Controlling segmentation in cutting of metals
No full textWe examine segmented chip formation and associated flow dynamics in cutting of metals of low-tomoderate workability using high-speed imaging. Segmentation is initiated by a surface instability formation of a ductile crack in a prow - on workpiece surface ahead of the tool, this crack then propagates towards the tool tip. Prow-crack initiation occurs at a critical strain 0.75 that is independent of material and deformation geometry. This ductile failure is analyzed in terms of local hydrostatic stress state and stress triaxiality. Material-agnostic methods to suppress and enhance segmentation using constrained cutting and a mechanochemical effect are demonstrated