Maximum Kinetic Energy Research Articles

On the beta decay-induced radiation damage

The present work proposes the methods to calculate beta decay-induced atomic displacement damage, including the emitted electron-induced damage and the residual nucleus-induced damage using three-body kinematics. Compared with the standard Norgett-Robinson-Torrens (NRT) metric of the number of Displacements per Atom (DPA), the modified NRT proposed in the present work based on the definition of threshold displacement energy leads to 36% more DPA induced by the emitted electron of 56Mn beta decay. The example of 56Mn beta decay shows that the emitted electron-induced DPA is fewer than the DPA induced by the residual nucleus by a factor of 14. The residual recoil energy should be taken into account for elements such as iron, nickel, chromium, aluminum, and especially for silicon, whereas the maximum kinetic energy of beta decay residual is below the threshold of atomic displacement for tungsten.

Performance investigation of a volute porous tongue of a turbocharger turbine

The design for better performance of the spiral housing volute used commonly in radial and mixed inflow gas turbines is of prime importance as it affects the machine stage at both design and off design conditions. The tongue of the scroll divides the flow into two streams, and represents a severe source of disturbances, in terms of thermodynamic parameter uniformity, maximum kinetic energy, the right angle of attack to the rotor and minimum losses. Besides, the volute suffers an undesirable effect due to the recirculating mass flow rate in near bottom vicinity of the tongue. The present project is an attempt to design a tongue fitted with cylindrical holes traversing normal to the stream wise direction, where on account of the large pressure difference between the top and the bottom sides of the tongue will force the recirculating flow to go through the rotor inlet. This possibility with its limitations has not yet been explored. A numerical simulation is performed which might provide our suitable objectives. To achieve this goal the ANSYS code is used to build the geometry, generate the mesh, and to simulate the flow by solving numerically the averaged Navier Stokes equations. Apparently, the numerical results show evidence of favorable impact in using porous tongue. The realization of a contact between the main and recirculation flow by drilled holes on the tongue surface leads to a flow field uniformity, a reduction in the magnitude of the loss coefficient, and a 20 % reduction in the recirculating mass flow rate.

Experiment and simulation study of erosion mechanism in float glass due to rhomboid particle impacts

A coupled FEM-SPH numerical model is established to investigate the erosion behaviors of float glass subjected to angular particle impacts. The accuracy of the model is validated by comparing with measured data onto float glass erosion experiments. The model is then used to simulate single rhomboid particle impact on float glass surfaces under various conditions including impact velocity (20~110 m/s), impact angle (60~90 deg) and initial orientation angle (−10~50 deg). The results show: (1) similar to ductile material, the critical orientation angle marking the maximum kinetic energy loss is also observed for brittle material like float glass. Under the critical impact condition, the kinetic energy loss of rhomboid particle is up to 98.69% and 94.82% during vertical and incline impact respectively; (2) The formation and propagation of radial cracks and lateral cracks are determined by the combined effects of impact angle and orientation angle, and the brittle crater formed by the backward impact is wider and shallower than that of forward impact; (3) The behaviors of brittle splashing (i.e., fragments and chips) are successfully reproduced by the model, and the particle rotation behaviors after the impact significantly influences the direction of splashing stream which is less influenced by the impact angle; (4) The impact velocity determines the extent of material damages, and has little influence on the rotation behaviors of particle. Under the condition of constant kinetic energy, the size of particle (1.0~5.0 mm) has little effect on the erosion mechanisms in terms of crater depth, crater profile, splashing flow pattern and crack propagation.

Atmospheric Diffusivity: A New Energetic Framework for Understanding the Midlatitude Circulation Response to Climate Change

AbstractThe midlatitude circulation response to climate change is not well understood. Within an energetic framework the circulation is connected to the atmospheric diffusivity. Here we define a novel diagnostic diffusivity framework as a tool for interpreting changes in the midlatitude atmospheric circulation. The diffusivity is computed by dividing the zonally and vertically integrated transient eddy moist static energy (MSE) transport by the zonal‐mean 925 hPa MSE gradient, and we investigate the diffusivity response to global‐scale sea surface temperature (SST) perturbations in aquaplanet and Atmospheric Model Intercomparison Project (AMIP) general circulation model simulations. The midlatitude diffusivity maximum shifts poleward with increasing SST in both the aquaplanet simulations and Southern Hemisphere winter of the AMIP simulations. Our framework indicates that this diffusivity shift is associated with Ferrel circulation and 925 hPa MSE gradient changes, rather than with total MSE transport changes. The MSE gradient‐related shift cannot be understood purely in terms of Clausius‐Clapeyron changes in specific humidity following the global‐mean temperature response, because atmospheric temperature gradients change significantly even when SST gradients are held fixed. The intensity of the diffusivity maximum also increases with SST for the aquaplanet configuration but is relatively insensitive to SST for AMIP Southern Hemisphere winter. Additional energy balance model experiments suggest that while diffusivity changes caused by SST perturbations can be large, their effect on zonal‐mean temperature is minor. Finally, the latitudes and intensities of the diffusivity maxima are strongly correlated with the same properties of the zonal‐mean eddy kinetic energy maxima. However, existing theories cannot adequately explain these linear relationships.

Constraints on the kinetic energy of type-Ic supernova explosion from young PSR J1906 + 0746 in a double neutron star candidate* *Project supported by the National Natural Science Foundation of China (Grant Nos. U1938117, U1731238, 11703003, and 11647114), the International Partnership Program of Chinese Academy of Sciences (Grant No. 114A11KYSB20160008), the National Key Research and Development Program of China (Grant

So far among the nineteen pairs of detected double neutron star (DNS) systems, it is a usual fact that the first-born recycled pulsar is detected, however the youngest DNS system PSR J1906+0746, with the characteristic age of 113 kyr, is one of the three detected DNS as a non-recycled and second-born NS, which is believed to be formed by an electron capture or a low energy ultra-stripped iron core-collapse supernova (SN) explosion. The SN remnant around PSR J1906+0746 is too dim to be observed by optical telescopes, then its x-ray flux limit has been given by Chandra. A reference pulsar PSR J1509-5850 with the young characteristic age of 154 kyr was chosen as an object of comparison, which has an SN remnant observed by Chandra and is believed to be formed by iron core SN explosion. We impose a restriction on the maximum kinetic energy of electron-capture (EC) SN explosion that induces the formation of PSR J1906+0746. The estimated result is (4–8)×1050 erg (1 erg = 10−7 J), which is consistent with that of the published simulations of the EC process, i.e., a lower value than that of the conventional iron core SN explosion of (1–2) × 1051 erg. As suggested, EC process for NS formation is pertained to the subluminous type Ic SN by the helium star with ONeMg core, thus for the first time we derived the kinetic energy of EC SN explosion of DNS, which may be reconciled with the recent observation of type Ic SN 2014ft with kinetic energy of 2 × 1050 erg.

Effect of Sodium Hydroxide Treatment on Physico-chemical, Thermal, Tensile and Surface Morphological Properties of Pongamia Pinnata L. Bark Fiber

ABSTRACT Surfaces of Pongamia pinnata L. fiber (PPF) were modified by the 5% (w/v) sodium hydroxide solution with the various immersing period as 15, 30, 45, 60 and 75 minutes. Chemical compositional analysis evidenced that 5% (w/v) sodium hydroxide solution with 60 minute immersing period is optimum treatment. Removal of lignin content from the optimally treated PPF was detected through the chemical analysis as well as Fourier Transform-Infrared spectroscopy. X-ray diffraction analysis outcomes established the enhancement in the crystallinity index (45.31% to 52.43%) and crystallite size (5.43 nm to 8.32 nm) of the optimally surface-modified PPF. Improvement in the maximum cellulose degradation temperature (332°C to 348°C) and kinetic activation energy of the optimally-surface modified fibers (68.642 KJ/mol to 72.563 KJ/mol) were acknowledged from differential thermogravimetric curve and broido plots. Scanning electron microscope and atomic force microscopy investigations visualized the improvement in surface roughness of the PPF after alkalization. All the above findings authorized the suitability of optimally surface modified PPF as reinforcement in lightweight polymer composite applications.

The phase shift between potential and kinetic energy in human walking.

It is known that mechanical work to sustain walking is reduced, owing to a transfer of gravitational potential energy into kinetic energy, as in a pendulum. The factors affecting this transfer are unclear. In particular, the phase relationship between potential and kinetic energy curves of the center of mass is not known. In this study, we measured this relationship. The normalized time intervals α, between the maximum kinetic energy in the sagittal plane (Ek) and the minimum gravitational potential energy (Ep), and β, between the minimum Ek and the maximum Ep, were measured during walking at various speeds (0.5-2.5 m s-1). In our group of subjects, α=β at 1.6 m s-1, indicating that, at this speed, the time difference between Ep and Ek extremes is the same at the top and the bottom of the trajectory of the center of mass. It turns out that, at the same speed, the work done to lift the center of mass equals the work to accelerate it forwards, the Ep-Ek energy transfer approaches a maximum and the mass-specific external work per unit distance approaches a minimum.

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.

Application of electrical action to design and analysis of magnetically driven solid liner implosion

As a typical cylindrical-convergent drive technique, magnetically driven solid liner implosion could compress interior substance with a shock or quasi-isentropic manner, which has been widely used to investigate the hydrodynamic behavior, the dynamic characteristics of material and fusion energy and so on. For aspecific facility, the implosion parameters depend on material, radius and thickness of the liner, and the ablation of liner restrict the optional parameters. The concept of electrical action is introduced via thin shell model, which not only is the representation of states for conductive metal, but also indicates the change of liner velocity under the condition of thin shell hypothesis. The result shows that the outer velocity of liner increases linearly with electrical action and is directly proportional to liner thickness but inversely proportional to liner density. The incompressible zero-dimensional model is used to calculate the dynamic parameters of thin shell liner, including the implosion time, the outer interface velocity, the implosion kinetic energy, and the electrical action under the condition of low linear current density. There exist optimal radius and thickness which can achieve the maximum velocity, momentum, and kinetic energy. The aluminum is suitable for reaching higher velocity and the copper can obtain higher pressure according to a proportionality coefficient <i>Q</i><sub>b</sub>/<i>ρ</i> which is an intrinsic quality of metal. A one-dimensional (1D) elastic plastic magnetic hydrodynamic code which is called SOL1D is developed to simulate liner implosion behavior. The modified relationship between resistivity and electrical action is introduced to SOL1D, which can adapt higher hydrodynamic pressure. According to current waves, the 1D code can be used to simulate liner implosion behavior for all kinds of current densities. The 1D simulation liner velocity is in agreement with both the experimental results and the electrical action model for liner implosion experiment on FP-1 facility. The simulation of isentropic compression experiment at ZR facility shows that the magnetic diffusion process is suppressed at extra high current density and hydrodynamic pressure, and the electrical action is larger than the experimental value of wire electrical explosion. The zero-dimensional (0D) and 1D simulation show that estimating the liner velocity and liner phase changing via the electrical action are suitable when thin shell hypothesis and low current density assumption are satisfied.

Energy conversion and deposition behaviour in gravitational collapse of granular columns

The high-density gravitational collapse of granular columns is very similar to the movements of large collapsing columns in nature. Based on the development of dangerous columnar rock mass in fields, granular column collapse boundary condition in the physical experiments of this study is a new type of boundary conditions with a single free face and a three-dimensional deposit. Physical experiments have shown that the mobility of small particles during the collapse of granular columns was greater than that of large particles. For example, when particle size was increased from 5 to 15 mm, deposit runout was decreased by about 16.4%. When a column consisted of two particle types with different sizes, these particles could mix in the vicinity of layer interfaces and small particles might increase the mobility of large particles. In the process of collapse, potential and kinetic energy conversion rate is fluctuated. By increasing initial aspect ratio a, the ratio of the initial height of column to its length along flow direction, potential and kinetic energy conversion rate is decreased. For example, as a was increased from 0.5 to 4, the ratio of maximum kinetic energy obtained and total potential energy loss was decreased from 47.6% to 7.4%. After movement stopped, an almost trapezoidal body remained in the column and a fanlike or fan-shaped accumulation was formed on the periphery of column. Using multiple exponential functions of the aspect ratio a, the planar morphology of the collapse deposit of granular columns could be quantitatively characterized. The movement of pillar dangerous rock masses with collapse failure mode could be evaluated using this granular column experimental results.

Numerical Simulation of the Flow Field and Pollutant Dispersion around a Hill under Different Thermal Stratifications

AbstractThis paper applied a commercial computational fluid dynamics code, STAR-CD, with the renormalization group k–ε turbulence model to simulate the flow and dispersion of contaminants released from a source on the windward side of a hill under different thermal stratifications. In the wake region, the influence of atmospheric stratification on the flow field is inconspicuous under neutral and unstable conditions because of the effect of mechanical disturbance. However, this influence becomes slightly conspicuous under stable conditions. When atmospheric stratification is stable, in the range of z/H < 1.0 (where z is height above the surface and H is height of the hill), the velocity deficits are smaller than those under neutral and unstable conditions. The maximum turbulence kinetic energy (TKE) appears in the wake regions, and the variation in TKE is significantly lower than that under neutral and unstable conditions. When atmospheric stratification is unstable, the vertical and horizontal spread of the plume is slightly greater than that under neutral and stable conditions and the maximum concentration is less than that under neutral conditions. When the Froude number is large (~11; Brunt–Väisälä frequency = 0.52), atmospheric stratification is slightly stable, the structure of flow around the hill is generally similar to that under neutral conditions, and the high-concentration regions are large on the windward side of the hill. Smaller high-concentration regions just appear on the windward side of the hill under unstable conditions. The pollutant concentrations in the wake region of the hill increase as a result of the effect of thermal stability, and the vertical spreading range of the plume along the downwind axis (x axis) is larger than that under neutral and stable conditions.

Simulations for Flow-Symmetry Through r.avaflow in the General Two-Phase Mass Flow Model

Gravitational flows, e.g., landslide, debris flow and avalanches are hazardous mass wasting processes. The proper understanding of their dynamics is very important. As laboratory experiments can not perfectly model their initiation process and field assess of the live events are very difficult, numerical experiments have become the promising way for the study of their flow dynamics. Here we employ the enhanced version of two-phase mass flow model [33] through the open source computational code, r.avaflow to analyze the issue of symmetry in the flow. Two-phase debris mass are triggered from all the flanks of the three different pyramids (triangle-based, square-based and octagon-based) with different rotational symmetry and study the flow pattern along with maximum kinetic energy of the flow. Flow past two different types of obstacles (a tetrahedron and a square based pyramid) are also observed. The possible causes of asymmetry in the flow are also analyzed.

Thermoelastic analysis and multi-objective optimal design of functionally graded flywheels for energy storage systems

In this study, the multi-objective optimal design of functionally graded material flywheels is obtained using the non-dominated sorting genetic algorithm-II. The variations in temperature along the flywheel radius due to the operating conditions and environmental changes are taken into consideration in design optimization. Variations in the elastic and thermal properties of materials with temperature are taken into consideration for the first time, to the best of the authors’ knowledge. The thermoelastic equations of motion and the heat equation are derived and then solved by the generalized differential quadrature method. Results for temperature variation, radial displacement and von Mises stress are compared with the results of finite element analysis, and very good agreement is observed. Designs with optimal cross-sectional geometry and material distribution that give minimum mass and maximum kinetic energy are obtained.

Design of radiation shielding for the 4-MeV RF linac using the Monte Carlo simulation

A radio-frequency (RF) linear accelerator (linac) and related system for irradiation of electron beam on natural rubber is under the commissioning at the PBP-CMU Electron Linac Laboratory, Chiang Mai University. The maximum kinetic energy of electron beam that can be achieved from the accelerator is about 4 MeV. The bremsstrahlung radiation in the x-ray regime is produced when electrons interact with materials in the beam path. The radiation with the dose exceeding the regulation limit can be harmful for the personnel in the laboratory and public area. This research concentrates on design of radiation shielding to prevent the leakage of radiation from the accelerator area. Calculation of the photon’s energy deposition per volume due to the interactions of electron beam with materials in the irradiation system and surrounding area including the collision and bremsstrahlung processes was performed by using a Monte Carlo simulation software GEANT4. Shielding walls of the 4-MeV linac and its irradiation system consists of iron plates with the thickness of 2 cm for the side walls and 3 cm for the top wall. Results of the radiation calculation suggested that the photon’s energy deposition per volume outside the accelerator hall reduces by more than 99.5% after the shielding walls were added.

Simulation of square-frame dipole coils for steering of electron beam

This study focuses on magnetic field simulation of a square-frame steering magnet and electron beam dynamic simulations in its magnet’s field at the PBP-CMU Electron Linac Laboratory, Chiang Mai University. The small dipole magnets with the same design were constructed from four identical iron bars winding with 70 turns of copper-wire. They are used for steering electron beam with a maximum kinetic energy of about 2.0 MeV in the pre-injectors system of the electron accelerator. The magnetic field simulations were conducted by using computer programs POISSON and RADIA for two-dimensional and three-dimensional models, respectively. The maximum magnetic fields at an excitation current of 1 A were 44.30 and 57.32 Gauss for the 2D and 3D models, respectively. The magnetic effective length was 10.45 cm. The electron beam dynamic simulations in the 3D magnetic field map was performed by utilizing a computer program ASTRA to investigate the transverse electron beam distribution along the magnetic axis. The achievement of this study will be used as an important information for proper operation of the magnets at our facility.

An experimental investigation of flow resistance and turbulent flow in brush fish pass

The flow and turbulence structure of a brush fish pass was investigated in a 1:2 physical model for Reynolds numbers of 5·46 × 104–1·78 × 105 and Froude numbers of 0·18–0·72. Experiments were performed with three different bed slopes (2, 4, and 6%) and four different areal bristle densities. For each bed slope and bristle density, data were collected for six different relative submergences of emergent flexible bristles. Bristle density and channel bed slope were found to play a crucial role in the experiments. From dimensional analysis and physical model measurements and calculations, the friction factor was derived for the brush fish pass. The main findings can be summarised as follows; (a) flow resistance was found to be a function of the Cauchy number of the bristles, the channel bed slope and bristle density; (b) the channel bed slope is a main parameter that controls the maximum velocity and turbulent kinetic energy (TKE) magnitudes; and (c) the spatially averaged TKE seems to be considerably lower for the same dissipated power in a brush fish pass compared with other conventional fish passes (vertical slot and natural types). Hydraulic design recommendations are given to avoid a tumbling flow regime and drag coefficient scale effects.

Characterization of a new cellulosic natural fiber extracted from the root of Ficus religiosa tree

Physical, chemical, thermal and crystalline properties of new natural fiber extracted from the root of Ficus Religiosa tree(FRRF) are reported in this study. The chemical analysis and X-ray diffraction (XRD) analysis results ensured the presence of higher quantity of cellulose content (55.58 wt%) in the FRRF. Nuclear Magnetic Resonance (NMR) spectroscopy analysis is transported away to support the chemical groups present in the considered fibre. Thermal stability (325 °C), maximum degradation temperature (400 °C) and kinetic activation energy (68.02 kJ/mol.) of the FRRF areestablished by the thermo gravimetric analysis. The diameter (25.62 μm) and density (1246 kg/m3) of the FRRF have been found by the physical analysis. Scanning electron microscope analysis (SEM) and Atomic force microscope analysis (AFM) outcomes revealed that FRRF has the relatively smoothest surface. Altogether the above outcomes proved that novel FRRF is the desirable reinforcement to fabricate the fiber reinforced composite materials.

Optimum Placement of Piezo-Polymer Power Harvester for Epicardial Pacemaker

The major drawbacks of current pacemaker are the battery replacement. Patient will need additional surgery to replace the pacemaker unit with the new one. Utilization of rechargeable battery has been proposed to overcome this problem. However, recharging a battery within the body is not feasible due to tissue-heating and battery’s charge-and-discharge life-time. By those reasons, the utilization of piezo-polymer is suitable for a self-powered pacemaker as energy harvester. Piezo-polymer has been widely used as energy harvesting but none for cardiothoracic implantable device. This study focuses on specific implementation of piezo-polymer for epicardial pacemaker. The proposed fundamental research aims to identify the optimum location on the heart to put the piezo-polymer. This research will be conducted by simulation of left ventricle of heart via ANSYS. Heart stress-strain Finite Element Analysis (FEA) will be employed to obtain the maximum harvested power. The result shows the location of myocardial contraction that produces sufficient kinetic energy for the placement of the pacemaker. The heart 3-dimensional images are taken from cardiac-CT or cardiac-MRI to search the optimum location on the heart for energy harvesting and minimize pacing energy. In conclusion, the left ventricular wall motion and deformation caused by the cardiac wall movements have been analysed based on the left ventricle model in the simulation to get the location of the maximum kinetic energy formed.

Characterization of raw and alkali treated new natural cellulosic fibres extracted from the aerial roots of banyan tree

The objective of this investigation is to check the suitability novel cellulosic fibre extracted from the aerial roots of Banyan tree (ARBFs) as reinforcement in fibre reinforced plastics. The Fundamental properties of ARBFs such as density, tensile strength, chemical composition, crystallinity index, crystalline size, thermal stability, maximum degradation temperature and surface roughness were studied. The chemical analysis results revealed that after the alkalization cellulose content was improved while hemi-cellulose, lignin and wax content were demised. The enhancement in the crystallinity index (76.35% from 72.47%) and crystalline size (7.74 nm from 6.28 nm) of alkali treated ARBFs were evidenced by the X-ray diffraction analysis. Thermal analysis results confirmed that maximum degradation temperature (368 °C) and kinetic activation energy (75.45 kJ/mol) of alkali treated ARBFs had increased from 358 °C and 72.65 kJ/mol respectively. The results of scanning electron microscopic and atomic force microscopic analysis exhibited that impurities and wax on the outer surface of the ARBFs were removed after the alkali treatment. All the above finding concluded that ARBFs is the appropriate material to use as a reinforcement in fibre reinforced plastics.

Flow and heat transfer of nanofluid in a channel partially filled with porous media considering turbulence effect in pores

The flow and heat transfer of Al2O3–water nanofluid in a channel partially filled with porous media is investigated numerically. The turbulence effect in the porous media is taken under consideration in this article. A simple case is simulated first to evaluate the accuracy of the results in comparison with the available data. The turbulent kinetic energy profile is investigated at a flow cross section. The results show that the maximum turbulent kinetic energy occurs in the clear fluid region in the vicinity of the porous media region. The turbulent kinetic energy is a decreasing function of the porosity of the porous medium. The effect of porosity on the variation of turbulent kinetic energy decreases with the increase in the porosity of the porous medium. The turbulent kinetic energy in clear fluid and porous media regions decreases with the increase in nanofluid concentration from 0.01 to 0.03, and it increases with the increase in nanofluid concentration from 0.03 to 0.05. The temperature of the nanofluid increases with the increase in the nanofluid concentration and decrease in the porosity of porous media. It is shown that for this case, with the increase in nanofluid concentration and porosity of porous media, the skin friction coefficient increases and the Nusselt number decreases.