Dissipation Profiles Research Articles

Bio-Inspired Approaches to Safety and Security in IoT-Enabled Cyber-Physical Systems.

Internet of Things (IoT) and Cyber-Physical Systems (CPS) have profoundly influenced the way individuals and enterprises interact with the world. Although attacks on IoT devices are becoming more commonplace, security metrics often focus on software, network, and cloud security. For CPS systems employed in IoT applications, the implementation of hardware security is crucial. The identity of electronic circuits measured in terms of device parameters serves as a fingerprint. Estimating the parameters of this fingerprint assists the identification and prevention of Trojan attacks in a CPS. We demonstrate a bio-inspired approach for hardware Trojan detection using unsupervised learning methods. The bio-inspired principles of pattern identification use a Spiking Neural Network (SNN), and glial cells form the basis of this work. When hardware device parameters are in an acceptable range, the design produces a stable firing pattern. When unbalanced, the firing rate reduces to zero, indicating the presence of a Trojan. This network is tunable to accommodate natural variations in device parameters and to avoid false triggering of Trojan alerts. The tolerance is tuned using bio-inspired principles for various security requirements, such as forming high-alert systems for safety-critical missions. The Trojan detection circuit is resilient to a range of faults and attacks, both intentional and unintentional. Also, we devise a design-for-trust architecture by developing a bio-inspired device-locking mechanism. The proposed architecture is implemented on a Xilinx Artix-7 Field Programmable Gate Array (FPGA) device. Results demonstrate the suitability of the proposal for resource-constrained environments with minimal hardware and power dissipation profiles. The design is tested with a wide range of device parameters to demonstrate the effectiveness of Trojan detection. This work serves as a new approach to enable secure CPSs and to employ bio-inspired unsupervised machine intelligence.

Observations of Near-Surface Mixing Behind a Headland

Field observations were collected near the mouth of the Bagaduce River, Maine, in order to understand how complex features affect the intratidal and lateral variability of turbulence and vertical mixing. The Bagaduce River is a low-inflow, macrotidal estuary that features tidal islands, tidal flats and sharp channel bends. Profiles of salinity, temperature, and turbulent kinetic energy dissipation (ε) were collected for a tidal cycle across the estuary with a microstructure profiler. Lateral distributions of current velocities were obtained with an acoustic doppler current profiler. Results showed intratidal asymmetries in bottom-generated vertical eddy diffusivity and viscosity, with larger values occurring on ebb (Kz: 10−2 m2; Az: 10−2 m2/s) compared to flood (Kz: 10−5 m2/s; Az: 10−4 m2/s). Bottom-generated mixing was moderated by the intrusion of stratified water on flood, which suppressed mixing. Elevated mixing (Kz: 10−3 m2; Az: 10−2.5 m2/s) occurred in the upper water column in the lee of a small island and was decoupled from the bottom layer. The near-surface mixing was a product of an eddy formed downstream of a headland, which tended to reinforce vertical shear by laterally straining streamwise velocities. These results are the first to show near-surface mixing caused by vertical vorticity induced by an eddy, rather than previously reported streamwise vorticity associated with lateral circulation.

Modelling Stilling Basins for Sewage Networks

Concrete elements play an effective role in stilling basin design in terms of enhancing the dissipation of energy to prevent immoderate scouring of downstream structures. Proper appurtenances, such as wedge-shaped splitter blocks, baffle walls, inverted t-sections, rectangular walls, inverted L sections, and impact walls, are thus utilised with circular pipe outlets to create stilling basins that are shorter yet more effective, and thus more economical. This research was based on numerical analysis of stilling basins using FLOW-3D software; the resulting Froude numbers were compared with the Froude number of a case study, a stilling basin manhole created by the Karbala Government. This research thus examined the influence of Froude number, the arrangement and location of dissipators, and the height of the pipe inlet under different hydraulic condition in order to better simulate stilling basin models. The turbulent energy dissipation was found to vary from 16% to 85%. The results from the models showed that L-sections offered maximum turbulent energy dissipation (ΔE/E1), while the rectangular wall shape gave minimum turbulent energy dissipation (ΔE/E1). It was also observed that the maximum turbulent kinetic energy almost always occurred in the initial sections, with flow becoming generally less turbulent at the end sections. Thus, at the end of all stilling basins, the turbulent kinetic energy dissipation and turbulent kinetic energy profiles became more uniform. The proposed numerical simulation using FLOW-3D was shown to be a reliable tool for predicting and discussing the turbulent energy dissipation in stilling basins. Further conclusions included the fact that the maximum turbulent energy dissipation (ΔE/E1) increases as values of Fr increase. The results of this research could thus help hydraulic designers to consider their selections for the optimum design of stilling basins more carefully.

Thermographic analysis of failure for different rock types under uniaxial loading

Mining activities focus on the production of mineral resources for energy generation and raw material requirements worldwide and it is a known fact that shallow reserves become scarce. For this reason, exploration of new resources proceeds consistently to meet the increasing energy and raw material demand of industrial activities. Rock mechanics has a vital role in underground mining and surface mining. Devices and instruments used in laboratory testing to determine rock mechanics related parameters might have limited sensing capability of the failure behavior. However, methodologies such as, thermal cameras, digital speckle correlation method and acoustic emission might enable to investigate the initial crack formation in detail. Regarding this, in this study, thermographic analysis was performed to analyze the failure behaviors of different types of rock specimens during uniaxial compressive strength experiments. The energy dissipation profiles of different types of rocks were characterized by the temperature difference recorded with an infrared thermal camera during experiments. The temperature increase at the failure moment was detected as 4.45oC and 9.58oC for andesite and gneiss-schist specimens, respectively. Higher temperature increase was observed with respect to higher UCS value. Besides, a temperature decreases of about 0.5-0.6oC was recorded during the experiments of the marble specimens. The temperature change on the specimen is related to release of radiation energy. As a result of the porosity tests, it was observed that increase in the porosity rate from 5.65% to 20.97% can be associated to higher radiation energy released, from 12.68 kJ to 297.18 kJ.

Effects of Strong Photospheric Dissipation on the Spectra and Structure of Accretion Disks with Nonzero Inner Torque

Abstract We present numerical calculations of spectra and structure of accretion disk models appropriate for near-Eddington luminosity black hole X-ray binaries. Our work incorporates nonzero torque at the ISCO as well as several dissipation profiles based on first-principles three-dimensional disk interior simulations. We found that significant dissipation near the photosphere can produce steep power-law-like spectra for models with moderate viewing angles spanning a range of black hole spins while including inner torque pushes the spectral peak to higher energies. Consistent with previous studies, we also conclude that disks with stresses at the inner edge remain viable models for high-frequency quasi-periodic oscillations, especially given that increasing dissipation near the photospheres actually resulted in QPO power spectra with higher quality factors compared to those found in recent work.

Asymmetry of nonlocal dissipation: From drift-diffusion to hydrodynamics

We study dissipation in inhomogeneous two-dimensional electron systems. We predict a relatively strong current-induced spatial asymmetry in the heating of the electron and phonon systems -- even if the inhomogeneity responsible for the electrical resistance is symmetric with respect to the current direction. We also show that the heat distributions in the hydrodynamic and impurity-dominated limits are essentially different. In particular, within a wide, experimentally relevant interval of driving fields, the dissipation profile in the hydrodynamic limit turns out to be asymmetric, and the characteristic spatial scale of the temperature distribution can be controlled by the driving field. By contrast, in the same range of parameters, impurity-dominated heating is almost symmetric, with the size of the dissipation region being independent of the field. This allows one to distinguish experimentally the hydrodynamic and impurity-dominated limits. Our results are consistent with recent experimental findings on transport and dissipation in narrow constrictions and quantum point contacts.

Thermal analysis for optimized selection of cooling techniques for SiC devices in high frequency switching applications

The inception of wide bandgap power semiconductors has paved way for the evolution of highly efficient power switches. A deep understanding about the thermal characteristics of the SiC power device is essential to utilize its advantages in terms of higher thermal and power handling capability. The primary objective of this paper is to establish an accurate thermal model by proposing and comparing different methodologies for thermal analysis of commercially available SiC device, which in turn will aid to select optimum cooling techniques for higher system efficiency. Exponential curve fitting technique was exploited to deduce the parameters for RC equivalent network model. A high frequency sinusoidal pulse width modulated SiC MOSFET inverter with a fixed load was considered for electro-thermal analysis using a unified software platform PLECS. The effect of switching frequency on heat sink volume was established through simulation studies with imbibed datasheet parameters of a commercial power device. Finally, a 3-D model of the commercially available SiC power MOSFET in SOT-227B package was built to analyse the device heat dissipation profile for an optimized cooling choice. The proposed modelling approach serves to provide a platform for the thermal optimization of power devices and can be extended to other semiconductor devices.

Dissipation Profiles of Tristyrylphenol Ethoxylate Homologs in Lettuce under Greenhouse and Field Conditions.

Tristyrylphenol ethoxylates (TSPEOs) have been increasingly used in pesticide formulations as inert ingredients in China, but little information exists on the dissipation behavior of TSPEOs in foodstuffs. In this work, a rapid method for measuring TSPEO homologs in lettuce using QuEChERS and HPLC-MS/MS was established. This method was used to study the dissipation and distribution profiles of TSPEOs in lettuce. TSPEO homologs degraded rapidly under greenhouse and field conditions, with half-lives of 2.18-5.39 and 1.82-5.52 days, respectively. TSPEOn (n = 6-9) were relatively persistent in the field. The distribution profiles showed an obvious difference between the two conditions. TSPEOn (n = 14-18) degraded to shorter-chain TSPEOs with time, and a two-peak (TSP16EO and TSP10EO) homolog distribution profile occurred between 7 and 14 days of treatment under greenhouse conditions. This work improves the understanding of the dissipation behavior of TSPEO homologs in lettuce.

Hot spot generation, reactivity, and decay in mechanochemical reactors

In this work, a bottom-up modeling approach to describe the reactive conditions in mechanochemical reactors is presented. The approach is focused on the creation of hot spots as the mechanism of enhanced reaction. In this model, energy dissipated during a collision is converted to heat in the milling media, and the reaction proceeds thermochemically. The first step of the model, determining the energy dissipated during the collision, is done by treating the ball and powder bed as viscoelastic materials and using a Kelvin Voigt model. The energy dissipation profile from the collision model is imported into a COMSOL® simulation. The heat transfer through the powder bed, treated as a continuous medium, is calculated, providing the temperature, volume, and time needed to calculate reaction rates. The final result of the model is the extent of reaction over a single collision. To verify the approach, the mechanochemical decomposition of calcium carbonate is studied. The real-time CO2 production under varying milling frequencies is measured using an in-line mass spectrometer. The ball and mill velocities, as well as, collision frequencies is determined by analyzing high speed video of a transparent milling vessel. The model describes hot spots with temperatures exceeding 1000 K that persist for tens of milliseconds.

Toward Arbitrary Control of Lattice Interactions in Nonequilibrium Condensates

AbstractThere is a growing interest in investigating new states of matter using out‐of‐equilibrium lattice spin models in two dimensions. However, a control of pairwise interactions in such systems has been elusive as due to their nonequilibrium nature they maintain nontrivial particle fluxes even at the steady state. Here it is suggested how to overcome this problem and formulate a method for engineering reconfigurable networks of nonequilibrium condensates with control of individual pairwise interactions. Representing spin by condensate phase, the effective two spin interactions are created with nonresonant pumping, are directed with dissipative channels, and are further controlled with dissipative gates. The dissipative barriers are used to block unwanted interactions between condensates. Together, spatial anisotropy of dissipation and pump profiles allow an effective control of sign and intensity of the coupling strength between any two neighbouring sites independent of the rest of the spins, which is demonstrated with a 2D square lattice of polariton condensates. Experimental realization of such fully controllable networks offers great potential for reservoir computing, modelling of the systems of coupled oscillators, simulation of the new state of matters, studying the phase transitions in large‐scale systems, and optimization.

Comparison of modelling techniques for assessment of spillways

Theoretical equations, computational fluid dynamics (CFD) and physical modelling are the three main commonly and commercially used techniques to analyse the performance of current or proposed dam spillways. The purpose of this paper is to compare the aforementioned modelling techniques, and ascertain the most appropriate application for pertinent features commonly required for analysis on a typical spillway. My employment allows me the unique opportunity to explore each technique with a critical analysis of individual performance and accuracy. It also allows me access to a great deal of physically modelled dam spillway data, against which to validate the CFD model to ensure accuracy. The paper will study each technique if applicable for the following pertinent requirements: Q/H curve, out-of-channel flow, velocity profiles, energy dissipation, pressure and hydraulic profile.

Weak-shock wave propagation in polymer-based particulate composites

Shock waves are common in polymer-based particulate composites that are subjected to intermediate to high-velocity impact loading. However, quantitative information on the spatial variation of stress, particle velocities, and energy dissipation during the formation and propagation of weak-shock waves is limited. In this paper, a systematic experimental study is conducted to understand the characteristics of weak-shocks in polymer-bonded particulate composites. Specimens made of polymer-bonded sugar are subjected to a projectile impact loading, at varying velocities, using a modified Hopkinson pressure bar apparatus. Full-field displacement and strains of the deformed samples are obtained with the help of an ultrahigh-speed imaging and digital image correlation technique. Using the full-field displacement data, the shock wave velocity, shock front thickness, and the full-field stress fields are calculated. From the spatial stress field and the strain rate data, the spatial energy dissipation profile is also estimated. The effect of impact velocity on the spatial stress profile, shock wave velocity, and energy dissipation are discussed.

Intratidal and Fortnightly Variability of Vertical Mixing in a Macrotidal Estuary: The Gironde

AbstractIntratidal and fortnightly variability of turbulence at the mouth of a macrotidal estuary is explored in this study. Profiles of turbulent kinetic energy dissipation were estimated from a Vertical Microstructure Profiler, and velocity shear measurements and current velocities were collected with a vessel‐mounted Acoustic Doppler Current Profiler. Gradient Richardson numbers were quantified using density measurements from a Conductivity, Temperature, Depth profiler and squared vertical shear quantified from current velocities. All measurements were collected over one complete semidiurnal tidal cycle in both neap and spring tide conditions. Vertical eddy viscosity (Az) was quantified from the available data and was used as a proxy for vertical mixing. Results showed intratidal asymmetries in bottom‐generated turbulence during neap with Az larger during ebb tide (∼10−2 m2/s) than flood tide (∼10−3 m2/s) with the opposite occurring during spring tide with larger Az during flood (10−1 m2/s) than ebb (10−2 m2/s). Lateral processes produced elevated near‐surface mixing decoupled from bottom‐generated turbulence at the end of flood and ebb tide during neap and spring. The secondary flows were driven by Coriolis, and these flows either enhanced (neap tide, end of flood) or maintained (spring tide, end of ebb) total shear through slack tides producing near‐surface to midwater column turbulence. These results are the first of their kind to show midwater column mixing from lateral circulation driven by Coriolis in a well‐mixed system, which vary from the lateral processes previously shown to destabilize water columns in estuaries more influenced by stratification.

The energy dissipation at roundabout system

In this paper, we propose a cellular automata model to study the energy dissipation in the roundabout system. The energy dissipation and the phase diagram of the system in the space ([Formula: see text]) are constructed. The energy dissipation profile (SE[Formula: see text](i)), and the effect of the rate [Formula: see text] (i.e., the rate of vehicles with no aimed exit point) and the probability P[Formula: see text] of choosing the next exit point to leave the circulating lane on the energy dissipation are shown. The simulation results show that the energy dissipation explains the nature of the phases, the quasi-free-flow (Q-FF) phase take place on the free flow phase because some vehicles decelerate at the entry point. Likewise, the results also indicate that the energy dissipation takes small values with the increases of the two probability [Formula: see text] and P[Formula: see text] which enhance the environmental statutes of the roundabout system.

Deep learning‐assisted and combined attack: a novel side‐channel attack

A deep learning (DL)-assisted and combined side-channel attack (SCA) is exploited to disclose the secret key of an advanced encryption standard (AES) cryptographic circuit with a countermeasure. Different physical leakages of the protected AES cryptographic circuit such as power dissipation and electromagnetic (EM) emission are captured together at first. Then the deep neural networks are utilised to model the relationship between the power noise and the EM noise by analysing the captured power dissipation and EM emission profiles. Ultimately, a special power attack is performed on the protected AES cryptographic circuit to leak the secret key efficiently through using the EM noise to filter the power noise. As demonstrated in the results, for the conventional SCAs, the secret key of the protected AES cryptographic circuit is undisclosed to the adversary even if 1 million plaintexts are enabled. By contrast, only analysing 32,500 number of plaintexts are sufficient to leak the secret key if the DL-assisted and combined SCA is executed.

Spectra and Structure of Accretion Disks with Nonzero Inner Torque

Abstract We present numerical spectral and vertical structure calculations appropriate for near-Eddington-luminosity, radiation-pressure-dominated accretion disks around stellar-mass black holes. We cover a wide range of black hole spins and incorporate dissipation profiles based on first-principles three-dimensional MHD disk interior simulations. We also include nonzero stresses at the innermost stable circular orbit, which results in the disk effective temperature increasing rapidly toward the black hole and gives rise to rather extreme conditions with high temperatures and low surface densities. We found that local annulus spectra become increasingly characteristic of saturated Comptonization with decreasing distance to the black hole. While the spectra become harder with increasing black hole spin, they do not give rise to a broad power-law tail even at maximum spin. We discuss the implications of our results in the context of the steep power-law state and the associated high-frequency quasi-periodic oscillations observed in some X-ray binary systems.

Causal dissipation in the relativistic dynamics of barotropic fluids

This paper develops two causal four-field theories of relativistic fluid dynamics, one for viscous fluids that are barotropic and the other for viscous heat-conductive fluids that are “thermo-barotropic,” a property that is newly defined here. While similar to the deduction of a five-field theory in the authors’ article Causal dissipation for the relativistic dynamics of ideal gases [Freistühler, H. and Temple, B., Proc. R. Soc. A 473, 20160729 (2017)], the argumentation is consistently carried out in a way that stays closer to Eckart’s flow frame (than to Landau’s), and the result is directly compared with the four-field theories resulting from early proposals made by Eckart, Lichnerowicz, and Choquet-Bruhat. The key idea is to impose second-order symmetric hyperbolicity in the sense of Hughes, Kato, and Marsden [Arch. Rational Mech. Anal. 63, 273–294 (1976)], in the natural Godunov variables that make the corresponding system of perfect-fluid conservation laws symmetric hyperbolic in the first order sense. The new theory for viscous heat-conductive thermo-barotropic fluids belongs to the Hughes-Kato-Marsden class; the new theory for viscous general barotropic fluids lies on the boundary of that class. As in the five-field theory, the coefficients of bulk viscosity ζ, shear viscosity η, and, in the case of thermo-barotropic fluids, that of heat conductivity χ are free parameters, and in terms of these, the relativistic dissipation tensor is uniquely determined under three conditions which the authors propose as definitive: symmetric hyperbolicity, sharp causality, and first-order equivalence with Eckart—the requirement that the resulting equations be equivalent to the Eckart equations to leading order in ζ, η, and χ. The new theory for general viscous barotropic fluids complements the one given in the abovementioned paper for massive ideal gases. The new theory for viscous heat-conductive thermo-barotropic fluids notably includes the case of pure radiation, providing as one application a quantitative correction to the authors’ previous proposal in Causal dissipation and shock profiles in the relativistic fluid dynamics of pure radiation [Freistühler, H. and Temple, B., Proc. R. Soc. A 470, 20140055 (2014)].

Spatial and Temporal Variability of Dissipative Dry Beach Profiles in the Pacific Northwest, U.S.A.

ABSTRACT Diez, J.; Cohn, N.; Kaminsky, G.M.; Medina, R., and Ruggiero, P., 2018. Spatial and temporal variability of dissipative dry beach profiles in the Pacific Northwest, U.S.A. Dissipative beaches in the U.S. Pacific Northwest are subject to a marked seasonality in wave climate and water levels, which leads to periodic oscillations in the morphology of the typically dry part of the beach profile. The back-and-forth, seasonal sediment exchange between the emerged and submerged parts of the beach system induces two main dry-beach profile-equilibrium configurations. During approximately 70% of the year, the dry beach adapts its configuration to a uniform positive slope from the mean high-water level to the dune toe. The remaining 30% of the time, typically corresponding to summer, the profile adopts a berm-like profile. These changes are quantified by studying intra-annual and interannual variations of the dry-beach profile shape. For intra-annual variations, a monthly profiling campaign between July 201...

Bilayer graphene lattice-layer entanglement in the presence of non-Markovian phase noise

The evolution of single particle excitations of bilayer graphene under effects of non-Markovian noise is described with focus on the decoherence process of lattice-layer (LL) maximally entangled states. Once that the noiseless dynamics of an arbitrary initial state is identified by the correspondence between the tight-binding Hamiltonian for the AB-stacked bilayer graphene and the Dirac equation -- which includes pseudovector- and tensor-like field interactions -- the noisy environment is described as random fluctuations on bias voltage and mass terms. The inclusion of noisy dynamics reproduces the Ornstein-Uhlenbeck processes: a non-Markovian noise model with a well-defined Markovian limit. Considering that an initial amount of entanglement shall be dissipated by the noise, two profiles of dissipation are identified. On one hand, for eigenstates of the noiseless Hamiltonian, deaths and revivals of entanglement are identified along the oscillation pattern for long interaction periods. On the other hand, for departing LL Werner and Cat states, the entanglement is suppressed although, for both cases, some identified memory effects compete with the pure noise-induced decoherence in order to preserve the the overall profile of a given initial state.

Polymer Modified Concrete of Blended Cement and Natural Latex Copolymer: Static and Dynamic Analysis

This paper deals with the effect of blended cement and natural latex copolymer to static and dynamic properties of polymer modified concrete. The polymer was used copolymer of natural latex methacrylate (KOLAM) and copolymer of natural latex styrene (KOLAS) with composition of 1%, 5%, and 10% w/w of weight of blended cement in concrete mixture. They are tested for compressive strength, flexural strength, splitting tensile strength, and modulus elasticity for static analysis, and impact load and energy dissipation profile for dynamic analysis. The result shows that KOLAM with concentration 1% give better performance in static and dynamic properties. The KOLAM 1% gives improvement in flexural strength, splitting tensile strength and modulus elasticity about 4%, 13% and 3% compared to normal concrete. And for dynamic properties, KOLAM 1% could reduce impact load up to 35% and improve energy dissipation capacity about 45% compared to normal concrete. The concentration of KOLAM higher than 1% resulting negative effect to static and dynamic properties, except modulus of elasticity. For KOLAS, there were no positive trends of static and dynamic properties.