Dissipative Moment Research Articles

Refinement of the gear ratios of the vehicle transmission

A method is proposed to refine the transmission ratios of vehicles by matching the load modes of movement with the design parameters of the transmission, providing optimal speed and the ability to overcome road resistance. Overcoming the emerging forces of resistance to movement is considered from the conditions of energy consumption of the vehicle. To determine the main patterns that characterize the movement of the vehicle, the ratios of traction-dynamic properties were obtained according to the refined parameters of the transmission. The parameters showed some approximation to the existing values of the transmission, thereby ensuring the maximum speed and minimum fuel consumption of the vehicle. Keywords:vehicles, energy losses, longitudinal force of resistance to movement, torsional rigidity, transmission, dissipative moment, gear ratio. i.dyakov@ulstu.ru

Influence of dissipative asymmetry on the of rotation stability in a resisting medium of a asymmetric rigid body under the action of a constant moment in inertial reference frame

Assuming that the center of mass of an asymmetric rigid body is located on the third main axis of inertia of a rigid body, the influence of dissipative asymmetry on the stability of uniform rotation in a medium with resistance of a dynamically asymmetric rigid body is estimated. A rigid body rotates around a fixed point, is under the action of gravity, dissipative moment and constant moment in an inertial frame of reference. The stability conditions are represented by a system of three inequalities. The first and second inequalities have the first degree with respect to the dissipative asymmetry, and the third inequality has the third degree. The third inequality is the most difficult to study. Analytical studies of the influence of small and large dissipative asymmetries, restoring, overturning and constant moments on the stability of rotation of a rigid body are carried out. Conditions for asymptotic stability are obtained for sufficiently small values of the dissipative asymmetry and conditions for instability for sufficiently large values of the asymmetry. The stability conditions are written down to the second order of smallness with respect to the constant moment and the first - with respect to the restoring or overturning moments. Stability conditions for the rotation of a rigid body around the center of mass are studied.

ВПЛИВ ДИНАМІЧНОЇ НЕСИМЕТРІЇ НА СТІЙКІСТЬ ОБЕРТАННЯ У СЕРЕДОВИЩІ З ОПОРОМ ТВЕРДОГО ТІЛА ПІД ДІЄЮ ПОСТІЙНОГО МОМЕНТУ У ІНЕРЦІАЛЬНІЙ СИСТЕМІ ВІДЛІКУ

Under the assumption that the center of mass of an asymmetric rigid body is located on the third principal axis of inertia of a rigid body, the previously obtained conditions for the asymptotic stability of uniform rotation in a medium with resistance of a dynamically asymmetric rigid body are investigated. A rigid body rotates around a fixed point, is under the action of gravity, dissipative moment and constant moment in an inertial frame of reference. The stability conditions are presented as a system of three inequalities. The first and second inequalities have the first degree relative to the dynamic unbalance, and the third inequality has the third degree. The first and third inequalities are of the second degree with respect to the overturning or restoring moment, and the second inequality is of the first degree. The first and third inequalities are of the fourth degree with respect to the constant moment, and the second inequality is of the second degree. The third inequality is the most difficult to study. Analytical studies of the influence of dynamic unbalance, restoring and overturning moments on the conditions of asymptotic stability are carried out. Conditions for the asymptotic stability of uniform rotation in a medium with resistance to an asymmetric rigid body are obtained for sufficiently small values of dynamic unbalance. Sufficient stability conditions are written out up to the second order of smallness with respect to the constant moment and the first order of smallness with respect to the restoring and overturning moments. Instability conditions are obtained for sufficiently large dynamic unbalance. The effect of dynamic unbalance on the stability conditions for the rotation of a rigid body around the center of mass is studied. It is shown that in the absence of dissipative asymmetry, it is sufficient for asymptotic stability that the axial moment of inertia of a rigid body be greater than the double equatorial moment and that the well-known necessary stability condition for a symmetric rigid body be satisfied.

Summer Dystrophic Criticalities of Non-Tidal Lagoons: The Case Study of a Mediterranean Lagoon

Eutrophication determines algal blooms and the subsequent accumulation of organic matter in sediments, which, in turn, results in the dominance of anaerobic respiratory processes that release toxic gases. Dystrophy is a final dissipative moment that reduces the organic load in the sediment. A case of dystrophy occurring in the Burano lagoon (Tuscany, Italy) in 2021 is reported. The study examined the weather, physico-chemistry of the water, submerged vegetation and sediment labile organic matter. In spring, dissolved oxygen (DO) and pH showed high values, in an abundance of submerged vegetation, while low values had ammonium, nitrate and orthophosphate. In mid-August, as warm and moist sea breezes prevailed, hydrogen sulfide releases were produced, preceded by a sharp rise in ammonium and orthophosphate concentrations, which remained high until November. During dystrophy, DO varied between anoxia and oversaturation, the latter in Cyanobacteria blooms. Dystrophic waters evolved gradually due to microphytes blooms, which changed from Cyanobacteria, in August, to the Dinophyta Alexandrium tamarense, in September, and Bacillariophyta, in November. Sediment labile organic matter varied between 3% and 7%. Ruppia spiralis meadows suffered the total detachment of fronds and stems during the dystrophy and proved to be areas of accumulation of organic detritus, themselves sources of dystrophic phenomena.

ПРО СТІЙКІСТЬ РІВНОМІРНОГО ОБЕРТАННЯ У СЕРЕДОВИЩІ З ОПОРОМ НЕСИМЕТРИЧНОГО ТВЕРДОГО ТІЛА ПІД ДІЄЮ ПОСТІЙНОГО МОМЕНТУ У ІНЕРЦІАЛЬНІЙ СИСТЕМІ ВІДЛІКУ

Assuming that the center of mass of a rigid asymmetric body is on the third main axis of inertia of a rigid body, the conditions for the asymptotic stability of uniform rotation of a dynamically asymmetric solid rigid body with a fixed point are obtained. These conditions are obtained in the form of a system of three inequalities based on the Lénard-Shipar test, written in innormal form. The rigid body is under the action of gravity, dissipative moment and constant moment in the inertial frame of reference. The rotation of a rigid asymmetric body around the center of mass is studied. Uniform rotation around the center of mass of a rigid asymmetric body will be unstable in the absence of a constant moment. Cases of absence of dynamic or dissipative asymmetry are considered. It is shown that the equilibrium position of a rigid body will be stable only under the action of the reducing moment. Dynamic asymmetry has a more significant effect on the stability of rotation of an asymmetric rigid body than dissipative asymmetry. Stability conditions have been studied for various limiting cases of small or large values of restoring, overturning, or constant moments. It is noted that for sufficiently large values of the modulus of the reducing moment, the rotation of the asymmetric solid will be asymptomatically stable. If the axial moment of inertia is the greatest or the smallest moment of inertia, then at sufficiently large values of angular velocity, both under the action of the overturning moment and under the action of the reducing moment, the rotation of the asymmetric solid will be asymptomatically stable. Analytical studies of the influence of dissipative, constant, overturning and restorative moments on the stability of uniform rotations of asymmetric and symmetric solids have been carried out. It is shown that in the absence of dynamic and dissipative symmetries, the obtained stability conditions coincide with the known ones.

Seismic Behaviour of EC8-Compliant Moment Resisting and Concentrically Braced Frames

The design procedure codified within current Eurocode 8 for dissipative moment resisting and concentrically braced frames have led to the design of massive systems characterized in the most of cases by poor energy dissipation capacity. The research activity presented in the current paper addresses the identification of the main criticisms and fallacies in the current EN 1998-1 for those seismic-resistant typologies. In this regard, the design provisions and codified rules for both moment resisting frames (MRFs) and chevron concentrically braced frames (CCBFs) are critically discussed and numerically investigated. Static and incremental dynamic analyses were performed on a set of 3 and 6-story frames designed compliant to EN 1998-1. The results from the numerical analyses are reported and discussed.

The dynamical motion of a gyroscope subjected to applied moments

In the present work, the problem of the dynamical motion of a rigid body close to Lagrange’s gyroscope under the effectiveness of a gyro moment vector, perturbing moments, and a Newtonian field is examined. An averaging system of the governing equations of motion is gained in view of applying the averaging method. A case of linear dissipative moments is considered. The numerical solutions for the case of linear dissipative moments are achieved and represented in some plots to detect the well effect of the different parameters on the motion of the body. The prominence of this work is due to its great applications in physics and engineering industry.

Vibrations of an Euler-Bernoulli beam with hysteretic damping arising from dispersed frictional microcracks

We study free and harmonically forced vibrations of an Euler-Bernoulli beam with rate-independent hysteretic dissipation. The dissipation follows a model proposed elsewhere for materials with randomly dispersed frictional microcracks. The virtual work of distributed dissipative moments is approximated using Gaussian quadrature, yielding a few discrete internal hysteretic states. Lagrange's equations are obtained for the modal coordinates. Differential equations for the modal coordinates and internal states are integrated together. Free vibrations decay exponentially when a single mode dominates. With multiple modes active, higher modes initially decay rapidly while lower modes decay relatively slowly. Subsequently, lower modes show their own characteristic modal damping, while small amplitude higher modes show more erratic decay. Large dissipation, for the adopted model, leads mathematically to fast and damped oscillations in the limit, unlike viscously overdamped systems. Next, harmonically forced, lightly damped responses of the beam are studied using both a slow frequency sweep and a shooting-method based search for periodic solutions along with numerical continuation. Shooting method and frequency sweep results match for large ranges of frequency. The shooting method struggles near resonances, where internal states collapse into lower dimensional behavior and Newton-Raphson iterations fail. Near the primary resonances, simple numerically-aided harmonic balance gives excellent results. Insights are also obtained into the harmonic content of secondary resonances.

Про стійкість обертання несиметричного твердого тіла зі збудженням в середовищі, що чинить опір.

Assuming that the center of mass of a solid is on the third principal axis of inertia of a rigid body, on the basis of the Lienard-Shipar criterion, written in an innocent form, the asymptotic stability condition for the uniform rotation of a dynamically asymmetric rigid body with a fixed point as a system of three inequalities. The solid is under the action of attraction forces, dissipative torque and constant moment in the inertial and non-reference frames. The carried out studies of the asymmetry of a solid body and the dissipative moment, as well as of two constant moments on the stability conditions for uniform rotation of a rigid body. The results for a symmetric rigid body in the case of dynamic asymmetry of a rigid body and dissipative asymmetry are known.

On the universality of local dissipation scales in turbulent channel flow

Well-resolved measurements of the small-scale dissipation statistics within turbulent channel flow are reported for a range of Reynolds numbers from $Re_{{\it\tau}}\approx 500$ to 4000. In this flow, the local large-scale Reynolds number based on the longitudinal integral length scale is found to poorly describe the Reynolds number dependence of the small-scale statistics. When a length scale based on Townsend’s attached-eddy hypothesis is used to define the local large-scale Reynolds number, the Reynolds number scaling behaviour was found to be more consistent with that observed in homogeneous, isotropic turbulence. The Reynolds number scaling of the dissipation moments up to the sixth moment was examined and the results were found to be in good agreement with predicted scaling behaviour (Schumacher et al., Proc. Natl Acad. Sci. USA, vol. 111, 2014, pp. 10961–10965). The probability density functions of the local dissipation scales (Yakhot, Physica D, vol. 215 (2), 2006, pp. 166–174) were also determined and, when the revised local large-scale Reynolds number is used for normalization, provide support for the existence of a universal distribution which scales differently for inner and outer regions.

Exact relations between the moments of dissipation and longitudinal velocity derivatives in turbulent flows.

Following an approach by Siggia, we present coefficients C(n) relating the moments of the dissipation of kinetic energy 〈ɛ〉 and the longitudinal velocity gradient 〈∂u(1)/∂x(1)〉 under the assumption of isotropy and continuity. Particularly, we find that the moment 〈ɛ(n)〉 of order n is completely determined by 〈(∂u(1)/∂x(1))(2n)〉 and an order- (and viscosity-) dependent coefficient for all n under the assumption of (local) isotropy. This implies that all theories which specify 〈ɛ(n)〉 also implicitly determine 〈(∂u(1)/∂x(1))(2n)〉 and vice versa. As a corollary to the direct connection between the moments of the dissipation and the longitudinal velocity gradient, the even standardized moments of order 2n of ∂u(1)/∂x(1) (flatness, hyperflatness, and so on) are directly related to the ratio of the moments 〈ɛ(n)〉/〈ɛ〉(n). We compare the theoretical values of the coefficients C(n) up to n=6 with homogeneous isotropic DNS data ranging from Re(λ)=88 to Re(λ)=529.

Local dissipation scales and energy dissipation-rate moments in channel flow

AbstractLocal dissipation-scale distributions and high-order statistics of the energy dissipation rate are examined in turbulent channel flow using very high-resolution direct numerical simulations at Reynolds numbers ${\mathit{Re}}_{\tau } = 180$, $381$ and $590$. For sufficiently large ${\mathit{Re}}_{\tau } $, the dissipation-scale distributions and energy dissipation moments in the channel bulk flow agree with those in homogeneous isotropic turbulence, including only a weak Reynolds-number dependence of both the finest and largest scales. Systematic, but ${\mathit{Re}}_{\tau } $-independent, variations in the distributions and moments arise as the wall is approached for ${y}^{+ } \lesssim 100$. In the range $100\lt {y}^{+ } \lt 200$, there are substantial differences in the moments between the lowest and the two larger values of ${\mathit{Re}}_{\tau } $. This is most likely caused by coherent vortices from the near-wall region, which fill the whole channel for low ${\mathit{Re}}_{\tau } $.

“Reduced” multidimensional Vlasov simulations, with applications to electrostatic structures in space plasmas

A class of two-dimensional open-boundary kinetic plasma simulations characterized as reduced Vlasov simulations have been developed and applied to the study of double layers and electron holes in Earth’s auroral downward current region. In these simulations, full Vlasov phase-space dynamics is followed only in the direction of the magnetic field or imposed current, with a limited representation of phase space employed in the perpendicular spatial dimension. These reduced methods include a dissipative moment closure for unmagnetized species and limitation of perpendicular velocity space to a ring of modes at a fixed v⊥ for weakly magnetized species. Simulations with weakly magnetized ions exhibit ion-Bernstein waves in association with electron holes and simulations with weakly magnetized or unmagnetized electrons result in electron holes elongated perpendicular to B. These results are in qualitative agreement with satellite observations and previous particle simulations.

One method of gravitational attitude control of a rotating satellite

The mode of spinning up a low-orbit satellite in the plane of its orbit is studied. In this mode, the satellite rotates around its longitudinal axis (principal central axis of the minimum moment of inertia), which executes small oscillations with respect to the normal to the orbit plane; the angular velocity of the rotation around the longitudinal axis is several tenths of a degree per second. Gravitational and restoring aerodynamic moments were taken into account in the equations of satellite’s motion, as well as a dissipative moment from eddy currents induced in the shell of the satellite by the Earth’s magnetic field. A small parameter characterizing deviation of the satellite from a dynamically symmetric shape and nongravitational external moments are introduced into the equations. A two-dimensional integral surface of the equations of motion, describing quasistationary rotations of the satellite close to cylindrical precession of the corresponding symmetrical satellite in a gravitational field, has been studied by the method of small parameter and numerically. We propose to consider such quasistationary rotations as unperturbed motions of the satellite in the spin-up mode.

Численное исследование вращения твердого тела под действием суммы постоянного и диссипативного возмущающих моментов

Численное исследование вращения твердого тела под действием суммы постоянного и диссипативного возмущающих моментов

Distributed Terror and the Ordering of Networked Social Space

Truth be told, the “Y2K bug” was quite a disappointment. While the technopundits wooed us with visions of network failures worthy of millennial fervor, Jan. 1, 2000, came and went without even a glimmer of the catastrophic. Yet the Y2K “bug” did reveal the degree to which the American apocalypse now took the form of the network itself. The spaces of everyday life in America and elsewhere in a developed world produce and are produced by network structures that Manuel Castells has called “spaces of flow.” As such, Catastrophe today is marked more by dispersion and dissipation, rather than breakdown — a dis-strophe of social forms, structures, and experience.The dissipation of enactive networks does not, however, equate with a system failure. With the Internet “bubble burst” of March, 2000, the very exuberance of market flows were very much the conditions of possibility for both the irruption of a new economy and its sudden evaporation. It is not the ephemerality of these social forms and structures that disorients activities of everyday life in a network society, but rather our lack of control over distributed processes. The bubble burst, then, by no means sounded a death knell for distributed network functions. Rather, it marked a moment of increased misrecognition of the forms, structures, and practices that were the conditions of possibility for the event itself, as an ideology of authentication eclipsed a rhetoric of emergence and flow. Billions in capital disappeared in a matter of weeks, but the network forms and structures that allowed individual users “direct access” to the flows of capital remained in place for a normative virtual class, articulated as personalized and privatized spaces of control.

Structure functions and energy dissipation dependence on Reynolds number

The dependence of the statistics of energy dissipation on the Reynolds number is investigated in an experimental jet flow. In a range of about one decade of Reλ (from about 200 to 2000) the adimensional mean energy dissipation is found to be independent on Reλ, while the higher moments of dissipation show a power-law dependence. The scaling exponents are found to be consistent with a simple prediction based on the multifractal model for inertial range structure functions. This is an experimental confirmation of the connection between inertial range quantities and dissipation statistics predicted by the multifractal approach.

Non-linear resonance evolutionary effects in the motion of a rigid body about a fixed point

Evolutionary effects in the motion of a heavy dynamically symmetrical rigid body about a fixed point in cases close to the Lagrange case are investigated in the non-linear formulation. Evolutionary effects are due to perturbations acting on the body, namely, a small displacement of the centre of mass with respect to the axis of dynamic symmetry, a perturbing moment, constant in a connected system of coordinates, and dissipative moments. It is shown that the presence of perturbations leads to the existence of “attracting” or “repulsing” resonances, which determine the evolution of the system in non-resonance parts of the motion. The method of integral manifolds is used for singularly perturbed systems and the method of averaging. A qualitative representation of possible motions of a statically stable top in the phase plane, taking a lower-order resonance into account, is given.

The Effect of Dissipative Moments Caused by Liquid Body Viscosity on the Rotation Stability of a Space Object

The influence of dissipative forces in a viscous liquid that completely fills the cavities of a space object executing a rotational motion is analyzed. The Navier–Stokes equations are solved by expanding them into a series in terms of eigenfunctions of the boundary value problem on involving the resting liquid in rotation around the longitudinal axis of a cavity. The analytical solutions for coaxial cylindrical and concentric spherical cavities are obtained, in particular, for a straight circular cylinder and a sphere. The stability of the single-axis orientation of a space object filled with a viscous liquid is investigated. The dependences of rotation decay processes and drifts of the space object's longitudinal axis from a given direction are shown on the plane of constructive parameters.

A Model for the polar motion of the deformable Earth adequate for astrometric data

Refined analytical expressions for the frequencies corresponding to the Chandler motion of the pole and the diurnal rotation of the deformable Earth are derived. Numerical estimates of the period and amplitude of the polar oscillations are presented. The trajectory of the Chandler polar motion derived via numerical modeling is in qualitative and quantitative agreement with experimental data from the International Earth Rotation Service (IERS). An evolutionary model describing slow variations in the Earth’s rotation parameters under the action of the dissipative moments of the tidal gravitational forces on time scales considerably longer than the precession period of the Earth’s axis is constructed. The axis of the Earth’s figure tends to approach the angular momentum vector of the proper rotation.