Dissipation Time Research Articles

A Parameterization of Turbulent Dissipation and Pressure Damping Time Scales in Stably Stratified Inversions, and its Effects on Low Clouds in Global Simulations

AbstractIt is difficult for coarse‐resolution global models of the atmosphere to accurately simulate the observed distribution of low clouds. In particular, it is difficult for moist turbulence closure models to simulate sufficiently bright near‐coastal stratocumulus (Sc) without simulating overly bright marine shallow cumuli (Cu). To parameterize bright Sc, a turbulence parameterization must damp the turbulent fluxes of heat and moisture above cloud top in order to prevent excessive entrainment of dry air into cloud top. To parameterize dim shallow Cu, the subgrid variances of temperature and moisture must remain large, in order to permit partial cloudiness. However, damping the fluxes but not the variances just above cloud top is difficult if a parameterization uses a single “master” time scale to damp both. In nature, the above‐cloud fluxes are damped by pressure fluctuations, whereas scalar variances are damped by a different process, namely, turbulent dissipation. In a stably stratified inversion above cloud, pressure damping is large but turbulent dissipation is small. To avoid this problem, a multitime scale parameterization for damping has been developed. The damping parameterization has been implemented in a global model and evaluated. The parameterization is capable of dimming shallow Cu while producing adequately bright Sc.

Implementation of Symmetric Functions Using Memristive Nanocrossbar Arrays and their Application in Cryptography

VLSI technology makes the integration of multiple electronic components into a single electronic chip possible but Moore has already predicted that further miniaturization of VLSI chips will cause excess heat dissipation. Because of this impediment faced by this technology, the scientists have turned their focus to nano-technological alternatives to keep up the continuous device improvement and continue with the miniaturization procedure without facing any hurdle from the aspect of heat dissipation and space and time complexity. Memristor can be such a nano-alternative, which has the potential of very rapid execution, miniaturization and very low power consumption compared to transistor-based technology. The main objective of this paper is to show an application of symmetric function in cryptography. In order to do so, first, three-input and five-input symmetric functions are implemented in memristor-based nanocrossbar circuits. Then a dynamic circuit of symmetric functions is implemented where the input voltages convert the circuit to three-input or five-input symmetric function circuit as and when required. The simulation results show the satisfactory behavior of our proposed design.

Charge injection and decay of nanoscale dielectric films resolved via dynamic scanning probe microscopy

AbstractTo satisfy continual demands for higher performance dielectrics in multi‐layer ceramic capacitors and related microelectronic devices, novel characterization methods are necessary for mapping materials properties down to the nanoscale, where enabling materials developments are increasingly relevant. Accordingly, an atomic force microscopy‐based approach is implemented for characterizing insulator performance based on the mapping of discharging dynamics. Following surface charging by biasing a conducting tip contacting a dielectric surface, consecutive non‐contact Kelvin force surface potential mapping (KPFM) reveals charge dissipation via exponential decay. In barium titanate (BTO) thin films engineered with distinct microstructures but identical thicknesses, discharging rates vary by up to a factor of 2, with smaller grain size correlating to longer dissipation times, providing insight into optimal microstructures for improved capacitor performance. High‐resolution potential mapping as a function of time thereby provides a route for directly investigating charge injection and discharging mechanisms in dielectrics, which are increasingly engineered down to the nanoscale and have global implications given the trillions of such devices manufactured each year.

Calibrating the Wiedemann 99 Car-Following Model for Bicycle Traffic

Car-following models are used in microscopic simulation tools to calculate the longitudinal acceleration of a vehicle based on the speed and position of a leading vehicle in the same lane. Bicycle traffic is usually included in microscopic traffic simulations by adjusting and calibrating behavior models developed for motor vehicle traffic. However, very little work has been carried out to examine the following behavior of bicyclists, calibrate following models to fit this observed behavior, and determine the validity of these calibrated models. In this paper, microscopic trajectory data collected in a bicycle simulator study are used to estimate the following parameters of the psycho-physical Wiedemann 99 car-following model implemented in PTV Vissim. The Wiedemann 99 model is selected due to the larger number of assessable parameters and the greater possibility to calibrate the model to fit observed behavior. The calibrated model is validated using the indicator average queue dissipation time at a traffic light on the facilities ranging in width between 1.5 m to 2.5 m. Results show that the parameter set derived from the microscopic trajectory data creates more realistic simulated bicycle traffic than a suggested parameter set. However, it was not possible to achieve the large variation in average queue dissipation times that was observed in the field with either of the tested parameter sets.

Heat transfer and thermoregulation within single cells revealed by transient plasmonic imaging

Summary Cells, as the basic unit of life, undergo continuous heat transfer and dissipation during their metabolism, which is related not only to fundamental cellular functions but also massive applications. Unfortunately, thus far, we still know little about the heat transfer properties at the cellular or subcellular levels. Here, we demonstrated a transient microscopic method to measure the heat transfer in single cells. The thermal conductivity of different regions within a single cell shows a wide heterogeneity, and heat transfer in the region near the cell membrane is more active than the central region. However, the median values of thermal conductivity between different individual cells are quite close. A cellular-level heat regulation that responds to environmental temperature is observed in warm-blooded humans and chickens rather than in cold-blooded bullfrogs. According to the temperature-dependent cell metabolism, we proposed a hypothesis for cellular control of heat dissipation, which might be the cellular-level foundation of body thermoregulation.

Design and experimental study on a new heat dissipation method for watch-phones

In this work, a new heat dissipation method based on ultra-thin flattened heat pipe (UTHP) is developed for cooling watch-phones. The UTHP with a 0.4 mm thickness was designed to be a three-dimensional shape according to the watchcase shape. The UTHP cooling module (HPM) was soldered by three copper plates and a UTHP. The heat dissipation performance of the copper sheet cooling module (CSM) with the same dimensions was made for comparison with the HPM. The heat dissipation performance of the HPM was experimentally studied. The results indicate that the maximum heat dissipation powers of CSM and HPM were 0.8 and 0.9 W, respectively, at the surface temperature of the ceramic heater not exceeding 65 °C. At this time, ΔTc and Rhc of them were 9.18 °C and 9.86 °C/W, 3.98 °C and 2.63 °C/W, respectively. When the cooling module was cooled naturally from 65 to 37 °C, the heat dissipation time of HPM was 25 s shorter than that of CSM. The UTHP cooling module has a better heat dissipation performance, which can quickly reduce the chip temperature, eliminate the chip hotspot, and solve the heat dissipation issue of watch-phone.

Dephasing-assisted entanglement in a system of strongly coupled qubits.

Creation of entangled states of quantum systems with low decoherence rates is a cornerstone in practical implementation of quantum computations. Processes of separate dephasing in each qubit in experimentally feasible systems is commonly accepted to destroy entanglement. In this work, we consider a system of two strongly coupled qubits that interact with dephasing reservoirs. We demonstrate that interaction with dephasing reservoirs can contribute to the formation of a long-lived mixed entangled state with nonzero concurrence. The weight of the subradiant state in this mixed state tends toward unity if the dephasing rate is much larger than the radiative rate and less than the coupling constant between qubits. The lifetime of this state is proportional to the exponent of the ratio of the coupling constant to environmental temperature and can be, by orders of magnitude, larger than the system's characteristic dephasing and dissipation times. Therefore, high dephasing, along with strong coupling, contributes to the creation of an entangled state with a long lifetime. This result paves the way for creation of long-lived entangled states.

Oscillatory and tip-splitting instabilities in 2D dynamic fracture: The roles of intrinsic material length and time scales

Recent theoretical and computational progress has led to unprecedented understanding of symmetry-breaking instabilities in 2D dynamic fracture. At the heart of this progress resides the identification of two intrinsic, near crack tip length scales — a nonlinear elastic length scale ℓ and a dissipation length scale ξ — that do not exist in Linear Elastic Fracture Mechanics (LEFM), the classical theory of cracks. In particular, it has been shown that at a propagation velocity v of about 90% of the shear wave-speed, cracks in 2D brittle materials undergo an oscillatory instability whose wavelength varies linearly with ℓ, and at larger loading levels (corresponding to yet higher propagation velocities), a tip-splitting instability emerges, both in agreements with experiments. In this paper, using phase-field models of brittle fracture, we demonstrate the following properties of the oscillatory instability: (i) It exists also in the absence of near-tip elastic nonlinearity, i.e. in the limit ℓ→0, with a wavelength determined by the dissipation length scale ξ. This result shows that the instability crucially depends on the existence of an intrinsic length scale associated with the breakdown of linear elasticity near crack tips, independently of whether the latter is related to nonlinear elasticity or to dissipation. (ii) It is a supercritical Hopf bifurcation, featuring a vanishing oscillations amplitude at onset. (iii) It is largely independent of the phenomenological forms of the degradation functions assumed in the phase-field framework to describe the cohesive zone, and of the velocity-dependence of the fracture energy Γ(v) that is controlled by the dissipation time scale in the Ginzburg–Landau-type evolution equation for the phase-field. These results substantiate the universal nature of the oscillatory instability in 2D. In addition, we provide evidence indicating that the tip-splitting instability is controlled by the limiting rate of elastic energy transport inside the crack tip region. The latter is sensitive to the wave-speed inside the dissipation zone, which can be systematically varied within the phase-field approach. Finally, we describe in detail the numerical implementation scheme of the employed phase-field fracture approach, allowing its application in a broad range of materials failure problems.

Centrifuge model tests at Zhejiang University for LEAP-Asia-2019 and validation of the generalized scaling law

In the program of LEAP-Asia-2019, three dynamic centrifuge model tests on a 5-degree sloping ground composed of saturated Ottawa F-65 sand have been conducted at Zhejiang University to validate the generalized scaling law (GSL) by using the technique of "modeling of models". Firstly, the advantages and possible limitations of the generalized scaling law are revisited. Then a new scaling relation (GSR) treating the stiffness instead of the strain as an independent scaling factor is proposed in the frame of the generalized scaling law, and it further considers the effect of modulus reduction over wide strain range. Shear wave velocities of three models measured by bender elements and non-destructive step wave are analyzed to check the validity of Iai's Type II GSL at small strain range, and the response of acceleration, excess pore water pressure and displacement are analyzed to validate Iai's Type II GSL at large strain range. This study shows that Iai's Type II GSL generally applies well for small strain conditions and even the dynamic response of acceleration and pore pressure, but will introduce considerable errors for dissipation time and permanent displacement under large strain conditions. The proposed GSR exhibits better performance for all model tests from small to large strain levels.

Analysis of the Energy Dissipation Characteristic in an MMC-Based MVDC System With the Liquid Metal Current Limiter

Utilizing DCCBs to realize selective protection is a promising solution for dc fault isolation. While the large fault current and high fault energy make the dc fault interruption a crucial problem in the medium-voltage dc (MVDC) distribution system. A novel fault isolation strategy based on the liquid metal current limiter (LMCL) is proposed in this article to reduce the breaking current and dissipated energy of the dc circuit breakers (DCCBs). Based on a three-terminal MVDC distribution system, the fault current and energy dissipation characteristics for the reactor fault current limiter (L-FCL) and the LMCL are analyzed theoretically. The simulation results show that under the same breaking current, the dissipation energy and the dissipation time in the LMCL case are reduced by 48% and 41%, respectively. Besides, the influence of system parameters on breaking current and energy dissipation characteristics under the LMCL case is further analyzed. Finally, an experiment circuit is designed to verify the proposed scheme.

Pesticide treatment in biobed systems at microcosms level under critical moisture and temperature range using an Orthic Solonchaks soil from southeastern Mexico amended with corn husk as support

Agriculture effluents from cleaning and handling equipment used in pesticide applications can contaminate superficial and groundwater sources when not correctly disposed of. Biobeds using soil enriched with amendments represent a viable technology to control and minimize pesticide pollution of soil and water in farmlands. They are usually installed outdoors without protection, making them vulnerable to rain flooding, lack of moisture, drought, and intense heat or cold. Temperature (T) and moisture (M) of the biomixture are considered two of the most important physical factor affecting pesticide dissipation. This study aimed to evaluate the effect of T and M on the dissipation of five of the most used pesticides (carbofuran, atrazine, 2,4-D, diazinon, and glyphosate) in Yucatan State, Mexico. Three experiments using miniaturized biobeds considering optimal temperature and moisture (T of 30 ± 2 °C and 90% water holding capacity [WHC]) were performed. The optimal dissipation time and the effect of T, M variations, and volatilization was determined. The optimal dissipation time was over 14 days. Carbofuran was the least dissipated pesticide and glyphosate the most. The primary factor affecting pesticide dissipation was T (P < 0.05), reaching rates of dissipation of 99% at 45 °C. Variations of M in the biomixture were not significant on pesticide dissipation (P > 0.05). The white-rot fungi were observed; its presence was related to increments of T. Head Space analysis (at 45 °C) showed low pesticide volatilization (≤0.03%) for all pesticide used were quantified; water vapor condensation could reduce the pesticide volatilization for experimental conditions.

Why don’t we have better pain treatments?

Why don’t we have better pain treatments?

The modes of magnetic field generation in a low-mode model of αΩ-dynamo with α-generator varying intensity regulated by a function with an alternating kernel

The low-mode model αΩ-dynamo is used in this paper to simulate the modes of magnetic field generation with insignificant changes in the velocity field of a viscous fluid. In the framework of those model the α-effect intensity is regulated by the process that is included in the magnetohydrodynamic system (MHD-system) as an additive correction as a functional Z(t) depended on the magnetic field energy. Function that determines damped oscillations with variable damping frequency and constant damping coefficient, taken equal to one, is selected as kernel J(t) of functional Z(t). The research of the behavior of the magnetic field is carried out on large time scales, therefore, a rescaled and dimensionless MHD-system with the unit of time iquel the time of the magnetic field dissipation (104 years) for numerical calculations is used. The control parameters of the system are the Reynolds number and the amplitude of the α-effect, that include information about the large-scale and turbulent generators, respectively. Numerical simulation of the magnetic field generation modes was carried out for the values of the damping coefficient b = 1 and frequency a = 0.1, 0.5, 1, 5, 10. According to the results of numerical simulation, an increase in the values of the damping frequency, when the damping coefficient is equal to one, is characterized by a decrease in the inhibitory effect of the process Z(t) on the α-effect and an increase in the region of divergence of the magnetic field on the phase plane of the control parameters. In a comparative analysis with the results of the authors’ work, where the change of the α-effect intensity was determined by the function Z(t) with an exponential kernel and the same value of the damping coefficient, the following differences were noted: an increase in oscillations in both a magnetic and a velocity fields, the appearance of a chaotic regime of magnetic field generation at the value of the damping frequency equal to one, and also insignificant narrowing of the region of α-effect suppression at values of the damping frequency increasing to one.

Dissipation kinetics and harvest time residues of pyrazosulfuron-ethyl + pretilachlor in rice

The study on dissipation and harvest time residues of pyrazosulfuron-ethyl 0.75% and pretilachlor 30% WG after foliar application at seedling stage in rice at two doses 2000 g/ha (15 + 600 g/ha) and 4000 g/ha (30.0 + 1200 g/ha) was conducted at Integrated Farming System Research Station, Kerala Agricultural University, Thiruvananthapuram, Kerala. The pyrazosulfuron-ethyl and pretilachlor residues were estimated using LCMS/MS. The mean initial deposit of pyrazosulfuron-ethyl at recommended and double the recommended doses were 0.18 and 0.48 mg/kg, respectively. The residue dissipated with time and reached below limit of quantification (LOQ) of 0.01 mg/kg after 5 days in the recommended dose and 7 days in double the recommended dose. The mean initial deposit of pretilachlor at recommended and double the recommended dose were 8.84 and 15.50 mg/kg, respectively. The residue dissipated with time and reached below LOQ of 0.05 mg/kg within 15 days both in the recommended and double the recommended dose. The half-life values (days) were 1.29 and 1.80 for pyrazosulfuron-ethyl and 1.88, 1.37 for pretilachlor at recommended and double the recommended doses, respectively. In addition, the harvest time residues of pyrazosulfuron-ethyl 0.75% + pretilachlor 30% WG were estimated in samples of rice grain, husk, straw and cropped soil and were found below LOQ.

Description of the State in Time of Linear Automation Systems as a Consequence of Accumulation and Dissipation of Energy

The concepts of the state in time of the investigated linear automation system are proposed, which are based on the description of the processes of accumulation and dissipation of energy, as an attribute of the dissipation time, in the systems under consideration. It is shown that the investigated parameter (voltage across the capacitor UC) has projections in each structure of the temporal relationships of the considered state in time of the investigated linear automation system.

Heat dissipation in 3D printed cellular aluminum nitride structures

The improvement of heat dissipation in electronic and energy devices is a challenge that can be addressed through the use of highly porous materials. Presently, the additive manufacturing of 3D aluminum nitride is described, and different lattice patterns with porosities in the range 45–64 % are achieved by direct ink writing. All the structures are robust and the effective thermal conductivity (keff) for cuboid structures decreases by 50–75 % with the filament separation and shows anisotropic characteristics, since keff along the longitudinal axis of the scaffold is up to six times greater than for the transversal one. Heat transfer during free cooling experiments for cuboid and cylinder scaffolds, after rapid heating at temperatures above 1000 °C, takes place by radiation for temperatures >500 °C and by convection through the complete cooling process. The heat dissipation time constants of both processes decrease almost linearly with the designed scaffold parameters of porosity and rod separation.

In vitro investigation of the Flusso™ Bypass adapter efficiency upon ventilator circuit disconnect in a clinical simulated environment.

RationaleMechanically ventilated patients must be disconnected from the ventilator during intra-facility transfers. Intentional and accidental circuit disconnections represent a potential hazard to patients (sudden collapse and re-expansion of the alveoli) as well as to clinical staff (exposure to patient’s unfiltered exhalation). Therefore, avoiding abrupt circuit disconnections could better protect the patient’s health and reduce or eliminate contamination risks around clinical staff.ObjectiveThe purpose of this in-vitro work was to investigate and evaluate the potential for environmental exposure of Nitric Oxide (NO, as an indicator of any contamination exposure) before and after implementing the novel Flusso™ Bypass adapter during the disconnect procedure of a mechanical ventilator system.MethodsA mechanical ventilator delivering NO was connected to a breathing simulator with and without the Flusso™ Bypass adapter. The ambient NO concentration was measured when the circuit was briefly disconnected (3 s) during inhalation and exhalation. Both volume and pressure ventilation modes were used.Measurements and main resultsDisconnecting the standard ventilator circuit (pressure-controlled mode) without the Flusso™ Bypass adapter produced higher NO escape to the surroundings (compared with the volume-controlled mode), leading to a longer NO dissipation time. No ambient NO traces were detected when the Flusso™ adapter was used.ConclusionThe usage of the Flusso™ adapter drastically decreases the unwanted exposure among clinical staff dealing with potentially hazardous airborne biological aerosols emanating from the circuit. Avoiding abrupt disconnection in the ventilator circuit could reduce lung injuries and alveolar over distension and collapse.

Dippers from the TESS Full-frame Images. I. Results of the First One Year Data and Discovery of a Runaway Dipper

Abstract We present a comprehensive catalog of the dippers—young stellar objects that exhibit episodic dimming—derived from one year’s worth of data of the Transiting Exoplanet Survey Satellite (TESS) full-frame images. In the survey, we found 35 dippers using the convolutional neural network, most of them newly discovered. Although these dippers are widely distributed over the first half-hemisphere that TESS surveyed, we identified the majority’s membership with the nearest association Scorpius–Centaurus, Velorum OB2, and the nearby Orion molecular cloud complex. However, several dippers are likely to be located in the field. We also found three old dippers whose age exceeds 10 million years, which is considered to be the disk dissipation time. The color–color diagram indicates that these old dippers are likely to have an extreme debris disk. In particular, we found a runaway old dipper having a large three-dimensional velocity of 72 km s−1. The dippers in the field, which were probably escaping from their birth molecular clouds or were born outside the current area of star-forming regions, are more common than previously considered.

Dissipation of Sulfonamides in Soil Emphasizing Taxonomy and Function of Microbiomes by Metagenomic Analysis.

Sulfonamides (SAs) are widespread in soils, and their dissipation behavior is important for their fate, risk assessment, and pollution control. In this work, we investigated the dissipation behavior of different SAs in a soil under aerobic condition, focusing on revealing the relationship between overall dissipation (without sterilization and in dark) and individual abiotic (sorption, hydrolysis)/biotic (with sterilization and in dark) factors and taxonomy/function of microbiomes. The results showed that dissipation of all SAs in the soil followed the pseudo-first-order kinetic model with dissipation time at 50% removal (DT50) of 2.16-15.27 days. Based on, experimentally, abiotic/biotic processes and, theoretically, partial least-squares modeling, a relationship between overall dissipation and individual abiotic/biotic factors was developed with microbial degradation as the dominant contributor. Metagenomic analysis showed that taxonomic genera like Bradyrhizobium/Sphingomonas/Methyloferula and functions like CAZy family GT51/GH23/GT2, eggNOG category S, KEGG pathway ko02024/ko02010, and KEGG ortholog K01999/K03088 are putatively involved in SA microbial degradation in soil. Spearman correlation suggests abundant genera being multifunctional. This study provides some new insights into SA dissipation and can be applied to other antibiotics/soils in the future.

A parameterization of turbulent dissipation and pressure damping time scales in stably stratified inversions, and its effects on low clouds in global simulations

A parameterization of turbulent dissipation and pressure damping time scales in stably stratified inversions, and its effects on low clouds in global simulations