Analysis Of Energy Dissipation Research Articles

Experimental and numerical analysis of dynamic splitting mechanical properties and crack propagation for frozen sandstone

To reveal the dynamic tensile properties and crack growth law of frozen sandstone under impact loading, dynamic splitting tests (−30–20 °C) with different strain rates were carried out using a split Hopkinson pressure bar (SHPB), and the crack growth process of the specimens was captured using a high-speed camera. The study focused on the analysis of dynamic tensile mechanical properties, energy dissipation, crack growth, and failure modes of frozen sandstone. Numerical simulation analyses were also performed using LS-DYNA. The results indicated that: (1) The dynamic tensile strength has an obvious strain rate enhancement effect, and the strain rate sensitivity coefficient increased with a decrease in temperature. The Logistic function can characterize the relationship between the dynamic strain rate enhancement factor and the strain rate of frozen sandstone. (2) In the dynamic Brazilian disk (BD) test, the energy absorption rate showed a transition between the strain rates of 40 s−1 and 50 s−1, and there were two main failure modes of the specimen. The Y-direction secondary crack in mode II was caused by tensile stress in the Z-direction. (3) In the dynamic BD test, the central main crack (CMC) did not occur at the central position first, and its Z-direction propagation rate was linear with the strain rate. In the dynamic flattened Brazilian disk (FBD) test, the condition of CMC initiation was that the platform loading angle (2α) was greater than 10°. The dynamic tensile strength increased with an increase in 2α, and the correction coefficient was introduced in the calculation. This study can serve as a theoretical reference and basis for the study of the dynamic tensile properties of rock-like materials.

On energy dissipation or harvesting of tuned viscous mass dampers for SDOF structures under seismic excitations

In the past decade, tuned viscous mass dampers (TVMD) have been demonstrated as effective seismic resistant dampers. However, theoretical study on energy dissipation or energy harvesting of the TVMD has rarely been investigated, particularly, whether or not its optimal passive vibration control and energy dissipation maximization are consistent remains questionable. Here, from the theoretical perspective, we present an analysis of energy dissipation or energy harvesting of the TVMD in terms of damping power or output power, respectively. We derive the closed-form solutions of the average damping power of a single-degree-of-freedom (SDOF) structure-TVMD system under white-noise base excitations or seismic excitations modeled by the Kanai-Tajimi spectra, which is verified against the Monte Carlo simulations. Based on the closed-form solutions, the influences of the TVMD parameters, site conditions, and structural dynamic characteristics on the average damping power are analyzed via a parametric study. Theoretical results indicate that structural damping, site condition, structural period, frequency ratio, and inertance-to-mass ratio have a significant impact on the damping power or dissipated energy. In addition, the TVMD dissipates much more energy at a soft-soil site than at a stiff-soil site. At a stiff-soil site, the TVMD dissipates more energy for a short-period structure than for a long-period structure, however, at a soft-soil site, the law is the opposite. The study also presents the theoretical upper bound of the output power of an energy-harvesting TVMD. Particularly, results also illustrate that the maximization of TVMD energy dissipation is not consistent with the optimal passive vibration control. This study may shed light on the TVMD studies for seismic response control or energy harvesting purposes in the years to come.

Simple design of QCA-based T-flipflop with energy dissipation analysis for nanocomputing

Simple design of QCA-based T-flipflop with energy dissipation analysis for nanocomputing

Numerical analysis of vorticity transport and energy dissipation of inner-blade vortex in Francis turbine

The inner-blade vortex results in flow instability when Francis turbines operates at off-design conditions. The numerical method was conducted versus Francis turbine to study the inner-blade vortex characteristics. Firstly, the potential rothalpy gradient (PRG) is applied to analyze the inner-blade vortex evolution innovatively. The PRG is the main power which drives the inner-blade vortex develop in radial direction. The difference of potential rothalpy between hub and shroud curve occurs at 1/3 distance from blade inlet to outlet for deep load condition and 1/4 distance for part load condition. Then, the inner-blade vortex evolution is deeply analyzed based on the vorticity transport equation in cylindrical coordinate system. It indicates that the vorticity transport in radial and axial direction was mainly affected by stretching term and the Coriolis force term makes major contribution to vorticity in circumferential direction. Finally, the energy loss was calculated in Francis turbine by entropy production theory. The relative error was 3.51% and 3.07% for guide vane opening 8.28° and 10.85° between entropy production method and pressure drop method for efficiency calculation. And the interaction characteristics between inner-blade vortex and the energy dissipation was revealed by vorticity transport equation and entropy production method.

Comparative Computer Design of Four-bits Nanomultiplier

This paper presents a simulation circuit of a 4x4 Baugh–Wooley multiplier on a proposed one-bit full adder. The results included a comparison with other adders, an analysis of energy dissipation depending on temperature and dissipated power of the existing and proposed multipliers in mW. As a result, it was found that the proposed adder has better properties compared to similar ones. As a result of the work, the simulation circuit of the Baugh–Wooley multiplier 4x4 was performed, and the simulation result was obtained. Computer-edit simulate and design is performed in QCA DESIGNER software.

Bidirectional dry friction energy dissipater using layers

Many studies have been carried out to determine the performance of the energy dissipators proposed by different authors, mainly analyzing the hysteretic loops of loading and unloading. Likewise, the authors have sought to have simple, easy to manufacture and economical designs. Based on the above, the analysis of a passive bidirectional dry friction energy dissipator system is presented, whose main characteristic is the implementation of layer elements as structure, besides not requiring bolts or springs for the application of the preload. The study is carried out by means of numerical modeling using the finite element software Abaqus. The energy dissipation analysis is presented by means of hysteresis cycles, for different types of preload and number of stacked layer elements. The device, by means of one of the analyzed configurations, presents the capacity to dissipate 52 J of energy, being an innovative and functional design.

Analysis of Energy Dissipation on the Sealing Surface of Premium Connection Based on a Microslip Shear Layer Model

In high production gas wells, premium connections are subject to alternating loads and vibration excitation due to the change of fluid pressure exerted on the tubing string. The energy dissipation on the sealing surface of premium connections affects the sealing performance of premium connections. The present study proposes a new energy dissipation analysis method for the sealing performance of premium connections using a microslip shear layer mode, a novel technique to overcome and improve the limitations of existing analysis method of premium connections. In this paper, based on a microslip shear layer model, a vibration equilibrium equation of premium connection was established with the constraints of the taper of the sealing surface, the thread, and the torque shoulder. Then, the control equilibrium equations of the stick and microslip were derived, and the critical microslip tangential force and force–displacement hysteresis curves under different interface parameters were obtained by solving the equilibrium equations. The influence of different interface parameters on the energy dissipation of premium connection was discussed by using a standardized regression coefficient method. It was found that the friction coefficient influenced both the minimum and maximum microslip tangential forces, while the shear layer stiffness influenced only the minimum microslip tangential force. The greater the stiffness of the shear layer, the smaller the minimum microslip tangential force and the relative displacement of the contact surface, which made it easier to generate energy dissipation. The influence of the friction coefficient on energy dissipation was much greater than the stiffness of the shear layer. There was positive correlation between the friction coefficient and energy dissipation. While, there was a negative correlation between the stiffness of shear layer and energy dissipation. The results can provide a theoretical guide for micro sealing failure mechanism of premium connections under dynamic loads and expand the analysis method of metal seals.

Calculation and Analysis of Deformation Characteristic and Energy Dissipation of Flexible Bearings in Harmonic Drive for Industrial Robots

The flexible bearing is a key component of harmonic gear reducer for industrial robots. The wave generator cam as assembly part will significantly affect the flexible bearing transmission state. This paper derives the flexible bearing deformation coordination equation formula based on the harmonic drive theories, and the deformation characteristics of the flexible bearing formed by different wave generator cam shapes were studied. Combined the theory of clabellon with the load and deformation which are obtained, the deformation energy dissipation of the outer ring of the flexible bearing is discussed and quantitatively evaluated. The results showed that the wave generator cam shapes have a greater effect on the carrying capacity of the flexible bearing, and the dissipation of deformation energy of the flexible bearing can be effectively reduced by selecting appropriate wall thickness of the outer ring. Moreover, it was found that the two-roller wave generator deformation energy dissipation is the least at the same constraint.

Liquefaction induced permanent ground deformations and energy dissipation analysis based on smoothed particle hydrodynamics method (SPH): validation by large-scale model tests

Liquefaction induced permanent ground deformations and energy dissipation analysis based on smoothed particle hydrodynamics method (SPH): validation by large-scale model tests

Energy Dissipation and Damage Evolution Characteristics of Shale under Triaxial Cyclic Loading and Unloading

Rock engineering is highly susceptible to cyclic loads resulting from shale gas exploitation; it is very important to study the failure mechanism of underground rock mass under cyclic load. To investigate the energy dissipation and damage evolution characteristics of shale under triaxial cyclic loading and unloading conditions, a series of triaxial incrementally cyclic loading and unloading tests under different confining pressures (10 MPa, 15 MPa, 20 MPa, and 30 MPa) were carried out. The variation of plastic strain of shale under four confining pressures was analyzed, and the evolution characteristics of dissipated energy and energy dissipation ratio were discussed. The results show that: the peak strength and peak strain of shale increase with the increase in confining pressures. Meanwhile, the plastic strain of rock under cyclic loading increases rapidly first, then develops steadily, and finally increases sharply with the increase in axial strain. The energy dissipation ratio-strain curve presents a spoon-shaped evolution feature, and can be divided into three stages: a linear decline stage, a steady development stage, and a rapid increase stage, respectively. However, the trend of elastic modulus of shale was opposite to that of the energy dissipation ratio. Accordingly, the energy dissipation ratio can be regarded as the damage factor to describe the degradation of shale. Based on the evolution of dissipated energy, a theoretical equation of shale stress-strain evolution was established. By substituting the test data into the formula, it is found that the calculated results are basically consistent with the test data, and the peak strains and peak stress calculated by the equation are in good agreement with the test data. The findings could provide important theoretical support for the energy dissipation and damage evolution analysis in the failure process of shale under cyclic stress conditions.

Design of an efficient QCA-based median filter with energy dissipation analysis

Design of an efficient QCA-based median filter with energy dissipation analysis

Sobre la disipación de energía cinética turbulenta asociada con olas que aún no rompen

The turbulent kinetic energy dissipation is an essential quantity in the study of turbulence in fluids. In particular, on the transference of turbulent energy from large to small scales and determining its state of equilibrium and stationarity. This work has the purpose of understanding turbulence generation by non-breaking waves from turbulent kinetic energy dissipation analysis. Different groups of nonbreaking monochromatic waves with different slopes were mechanically constructed in a laboratory, whereby an acoustic device, the wave orbitals velocities were measure in various depths. Considering the inertial subrange in the power spectrum of components of turbulence velocity, a turbulent kinetic energy dissipation rate was quantified. It was detected that the magnitude of the turbulent kinetic energy dissipation rate increases with the wave slope and that deeper is invariant to axis rotations. It was distinguished that most of the profiles of the turbulent kinetic energy dissipation agree with an atypical logarithmic layer. Finally, a term of turbulence production was introduced, relative to nonbreaking wave orbital velocities. Unlike other turbulence production terms or approximations, it adequately reproduces the values of the turbulent kinetic energy dissipation rate regardless of wave slope, which established that the wave orbitals velocities shear is the generator mechanism of turbulence in a fluid under nonbreaking waves.

Energy dissipation analysis for large-strain cylindrical cavity expansion problem in cohesive-frictional soils

This work presents an energy dissipation analysis for large-strain cylindrical cavity expansion problem in cohesive-frictional soils. Based on the unified strength criterion and the non-associated flow rule, the process of cavity expansion in cohesive-frictional soils is regarded as an energy conversion problem. The energy dissipation solution for large-strain cylindrical cavity expansion is obtained by introducing the energy dissipation mechanism into the conventional cylindrical cavity expansion analysis. Subsequently, the effects of the intermediate principal stress, elastic deformation and large-strain in the plastic region are considered in proposed solution. Finally, according to the comparisons of the results of the stress distributions and non-dimensional expansion pressure with those in the published literature, the validity and reliability of the theoretical method are proved. The results show that the non-dimensional expansion pressure increases with the increase of the coefficient of intermediate principal stress, the stiffness of the response increases with the increase of the dilation angle, and most of the work done by the external force is transformed into the energy in the plastic region.

Loading Rate and Bedding Plane Coupled Effect Study on Coal Failure under Uniaxial Compression: Acoustic Emissions and Energy Dissipation Analysis

The mechanical behavior of coal is significantly influenced by the loading rate and bedding plane. In this paper, the uniaxial compression tests at different loading rates were conducted on coal specimens with vertical bedding (CSVB) and coal specimens with parallel bedding (CSPB), which were prepared by the coal with bursting liability from the Ordos deep mining areas, China. The results show that the uniaxial compressive strengths of CSVB and CSPB are positively correlated with the loading rate. The peak values of acoustic emission (AE) counts and accumulated absolute AE energy of CSVB and CSPB increase with the loading rate, and the AE parameters of CSVB are larger than those of CSPB. The variation rules of input energy density and elastic energy density are similar for CSVB and CSPB, but the variation rules of dissipated energy density in stage IV are different. As the axial load increases, the energy storage rate and energy dissipation rate of both coal specimen types increase and decrease, respectively. The bedding planes of coal and the loading conditions in the field should be fully considered when identifying the bursting liability of coal and forecasting coal burst. This study can provide a reference for coal burst warning and prevention under similar geological conditions in Ordos deep mining areas.

Design of SSG‐1 gate‐based cost‐efficient reversible digital circuits using quantum‐dot cellular automata technology

AbstractIn recent times, logic circuit designing with quantum‐dot cellular automata (QCA) technology is being comprehensively researched because of its inherent miniature size, ultra‐high speed, low power dissipation, and better switching frequency in the nanoregime. In this paper, QCA implementation of a 3 × 3 SSG‐1 reversible gate is first proposed. This gate is then used to design a reversible full adder, reversible 1‐bit comparator, and reversible 4:2 compressor. To evaluate the performance of the proposed QCA designs, an in‐depth comparison with existing designs has been performed. It is seen that the proposed SSG‐1 gate is efficient from the existing designs which eventually leads to efficient designs of adders, comparator, and compressor digital circuits. To further validate this, these digital circuits have also been compared with the literature and performance improvement is clearly observed in these circuits. In addition to this, energy dissipation analysis of all proposed logic gates and digital circuits is also performed for different kink energy levels using the QCA Pro tool and their respective energy dissipation maps are also obtained. Based on this, it is seen that the proposed designs are cost‐efficient and dissipate less energy which makes them more appropriate for designing higher‐order lower power circuits.

Morphology Evolution of Three-Dimensional Scours Under Submerged Jets

Through physical model tests, the three-dimensional morphological features and their scale changes with time were measured and comparatively analyzed during the scouring of a homogeneous granular bed surface using submerged oblique jets. The effects of various flow velocities and water cushion depths on the depth, length, and width of the scour hole were studied. At the early stage of scour formation, the morphological scales changed more dramatically, and the jet impact flow velocity had a more significant effect on the scour hole relative to the depth of the water cushion; for the final scales in all three directions of the scour, the scour depth developed at a more significant rate relative to the length and width of the scour. The correlation between the depth, length, and width of scour hole formation was achieved based on the time-domain variation pattern of scour hole scales. As the jet velocity increased and the depth of the water cushion decreased, the scour gradually developed from a wide-shallow morphology to a narrow-deep morphology; the impact of three-dimensional morphological features of the scour on hole depth gradually became obvious, appearing to inhibit the development of scour depth. The results of the present experimental tests offered an exploratory study of the effect of three-dimensional morphological features on the formation of jet scours, having constituted the basis for more rational analysis and evaluation of energy dissipation for the hydraulic operation in water conservancy projects.

Experimental Study on Dynamic Compressive Behaviors of Sand under Passive Confining Pressure.

Dynamic compressive tests of sand under passive confining pressure were carried out using a Split Hopkinson Pressure Bar (SHPB) setup. The dynamic response, energy dissipation and particle-breaking behaviors of sand subjected to high-speed impact were investigated. Sand specimens with moisture contents of 0%, 2%, 4%, 8%, 10% and 12% and relative densities of 0.1, 0.5 and 0.9 were prepared. The variation in the strain rate was controlled between 90 s−1 and 500 s−1. The specimens were confined in a designed sleeve to create passive confining pressure. The experimental results show that the sand specimens were extremely sensitive to the strain rate. When the strain rate was less than 400 s−1, the stress and strain of the specimens increased with the increase in the strain rate but decreased when the strain rate exceeded 400 s−1. The peak strain and peak stress increased with the increase in the relative density. Particle breakage was aggravated with the strain-rate increase. Compared with the specimen without water, the relative breakage rate of the specimen with a moisture content of 12% decreased by 30.53% when the strain rate was about 95 s−1 and by 25.44% when the strain rate was about 460 s−1. The analysis of energy dissipation revealed the essential cause of sand destruction. The specific energy absorption rate increased with the increases in the initial relative density and moisture content.

Next generation QCA technology based true random number generator for cryptographic applications

The penchant for almost all modern-day devices is high data and communication security. To achieve the highest standard of security, hardware-based encryption architectures like true random number generators (TRNG) and physically unclonable functions (PUF) supersede attack deterrence to any known software-based cryptography algorithm. The keys generated are random and unpredictable. This paper proposes a new architecture for TRNG in quantum-dot cellular automata (QCA) technology using feedback and feed-forward D flip-flop arrangement with small delay defects. A new optimized negative edge-triggered D flip-flop is presented using only 25-QCA cells. This unique and carefully curated TRNG structure ensures the generated output bits are highly unpredictable and truly random in behavior. Furthermore, 15 statistical tests designed for random number generators are performed. These test results validate the random nature of the generated outputs and unpredictable behavior of the proposed TRNG design. The energy dissipation analysis shows a significant improvement of 49.6% for energy dissipation per bit compared to existing designs.

A geometrical criterion for the dynamic snap-off event of a non-wetting droplet in a rectangular pore–throat microchannel

In porous media, non-wetting phase droplets snapping off in a constricted microchannel are one of the most common phenomena in two-phase flow processes. In this paper, the application range of the classic quasi-static criterion in rectangular cross section microchannels is obtained. For three different droplet breakup phenomena—total breakup, partial breakup, and non-breakup—observed in experiments when a non-wetting phase droplet passes through a microchannel constriction, the breakup is caused by the droplet neck snapping off in a channel constriction. A critical criterion for the dynamic snap-off event in a two-phase flow is proposed considering the effect of viscous dissipation by mechanical analysis, energy dissipation analysis, and many microfluidic experiments. When the droplet front flows out of the constriction, snap-off will occur if the surface energy release exceeds the required energy for viscous dissipation and kinetic energy conversion. The unique partial breakup phenomenon is affected by droplet surfactant distribution and the acceleration effect in the constriction center. This partial breakup phenomenon in experiments is an essential evidence for the non-uniform distribution of surfactants in the droplet surface. The results of this study contribute to understanding pore-scale mass transfer and flow pattern changes within porous media.

Experimental and numerical investigation on transverse impact resistance behaviour of pipe-in-pipe submarine pipelines after service time

The transverse impact resistance behaviour of pipe-in-pipe submarine pipelines after 15 years of service is studied experimentally and numerically. From drop hammer impact tests of 4 full-scale specimens, the influence of specimens’ span, corrosion and dent defect on the transverse impact resistance is studied in terms of failure mode, impact force-time history curves, displacement-time history curves, strain-time history curves and impact force-displacement curves. The experimental results indicate that the dynamic failure process consists of four stages, including primary vibration stage, secondary vibration stage, stable stage and unloading stage. As the suspension span of the specimen increases, the primary failure mode changes from local indentation to global bending deformation. The corrosion and the dent defect impair the impact resistance. Finite element (FE) models are then established and verified through comparison with experimental results. Numerical analyses indicate that the total impact energy is mainly dissipated by the outer pipe and the inner pipe according to the energy dissipation analysis for each component of the pipe-in-pipe specimens under transverse impact load. Parametric study is implemented finally to disclose the influence of the dimensions of pre-existing corrosion and dent defect on the transverse impact behavior of pipe-in-pipe submarine pipelines.