Showing papers on "Slip ratio published in 1999"
TL;DR: In this paper, the authors studied the friction of simulated fault gouge as a function of normal stress (σn = 25 to 70 MPa) and load point velocity (V = 0.001 to 10 mm/s).
Abstract: During earthquake rupture, faults slip at velocities of cm/s to m/s. Fault friction at these velocities strongly influences dynamic rupture but is at present poorly constrained. We study friction of simulated fault gouge as a function of normal stress (σn = 25 to 70 MPa) and load point velocity (V = 0.001 to 10 mm/s). Layers of granular quartz (3 mm thick) are sheared between rough surfaces in a direct shear apparatus at ambient conditions. For a constant σn, we impose regular step changes in V throughout 20 mm net slip and monitor the frictional response. A striking observation at high velocity is a dramatic reduction in the instantaneous change in frictional strength for a step change in velocity (friction direct effect) with accumulated slip. Gouge layers dilate for a step increase in velocity, and the amount of dilation decreases with slip and is systematically greater at higher velocity. The steady state friction velocity dependence (a-b) evolves from strengthening to weakening with slip but is not significantly influenced by V or σn. Measurements of dilation imply that an additional mechanism, such as grain rolling, operates at high velocity and that the active shear zone narrows with slip. Data from slow (μm/s) and fast (mm/s) tests indicate a similar displacement dependent textural evolution and comparable comminution rates. Our experiments produce a distinct shear localization fabric and velocity weakening behavior despite limited net displacements and negligible shear heating. Under these conditions we find no evidence for the strong velocity weakening or low friction values predicted by some theoretical models of dynamic rupture. Thus certain mechanisms for strong frictional weakening, such as grain rolling, can likely be ruled out for the conditions of our study.
251 citations
TL;DR: In this article, the consequences of slip at the wall on the flow of a linearly viscous fluid in a channel were investigated, and it was shown that the slip velocity depends on both the shear stress and the normal stress.
Abstract: The assumption that a liquid adheres to a solid boundary (“no-slip” boundary condition) is one of the central tenets of the Navier-Stokes theory. However, there are situations wherein this assumption does not hold. In this paper we investigate the consequences of slip at the wall on the flow of a linearly viscous fluid in a channel. Usually, the slip is assumed to depend on the shear stress at the wall. However, a number of experiments suggests that the slip velocity also depends on the normal stress. Thus, we investigate the flow of a linearly viscous fluid when the slip depends on both the shear stress and the normal stress. In regions where the slip velocity depends strongly on the normal stress, the flow field in a channel is not fully developed and rectilinear flow is not possible. Also, it is shown that, in general, traditional methods such as the Mooney method cannot be used for calculating the slip velocity.
163 citations
TL;DR: This article used total internal reflection (TIR•FRAP) to probe the velocity of a liquid near a wall with a resolution of the order of 100 nm and showed that simple Newtonian fluids can develop slip at the wall.
Abstract: We report a novel experimental technique using total internal reflection – fluorescence recovery after photobleaching (TIR‐FRAP) to probe the velocity of a liquid near a wall with a resolution of the order of 100 nm As an example of use, we have investigated the boundary condition of the liquid velocity during lubricated friction and studied the influence of a classical additive (stearic acid) in a base oil (hexadecane), and demonstrate that simple Newtonian fluids can develop slip at the wall
155 citations
TL;DR: In this article, the authors considered the gap dependence of the squeeze modulus of an elastic material and derived a more general derivation for the Newtonian case being also valid for full lubrication and large gaps.
Abstract: Squeeze flow between parallel plates of a purely viscous material is considered for small gaps both for a Newtonian and power law fluid with partial wall slip. The results for the squeeze force as a function of the squeezing speed reduce to the Stefan and Scott equations in the no slip limit, respectively. The slip velocity at the plate increases linearly with the radius up to the rim slip velocity v s . For small gaps H , the resulting apparent Newtonian rim shear rate—measured for a constant rim shear stress, i.e. an imposed force increasing proportional to 1/ H —yields a straight line if plotted versus 1/ H . The slope of the straight line is equal to 6 v s whereas the intersect with the ordinate yields the effective Newtonian rim shear rate to be converted into the true rim shear rate by means of the power law exponent. The advantage of the new technique is the separation of bulk shear and wall slip from a single test. A more general derivation for the Newtonian case being also valid for full lubrication and large gaps is used to explain the gap dependence of the squeeze modulus of an elastic material.
117 citations
12 Jul 1999
TL;DR: In this article, the optimal slip ratio control is achieved by maintaining the slip ratio to the value to give the maximum road friction, which means that the driving force of the vehicle is fixed at its maximum level.
Abstract: The target of our project is to realise a novel traction control system for an electric vehicle with four independently controlled in-wheel-motors. In each in-wheel-motor, the optimal slip ratio control is implemented beforehand to prevent wheel slip for vehicle stability control. The optimal slip ratio control is achieved by maintaining the slip ratio to the value to give the maximum road friction. This means that the driving force of the vehicle is fixed at its maximum level. As the driving force is affected by highly nonlinear adhesion characteristics between tire and road surface, real-time generation of the optimal slip ratio is necessary while the vehicle is moving. To estimate the adhesion characteristics, only the estimation of the slope of road friction curve is enough. To this aim, in this paper, the driving-force observer is newly designed to detect the road friction coefficient and the fixed-trace algorithm is applied to the slope estimation. The effectiveness of the proposed method is confirmed by simulation and experimental data obtained by laboratory-made electric vehicle "UOT Electric March".
111 citations
TL;DR: In this article, a hydrodynamic model for cocurrent gas-liquid downward flow through a packed-bed reactor operating in the trickle flow regime is developed, which involves area-averaged mass and momentum balance equations of each fluid as well as an expression for the capillary pressure gradient deduced from a momentum balance analysis at the gas−liquid interface.
64 citations
TL;DR: In this paper, a qualitative analysis was carried out to determine the slip coefficient as a function of two dimensionless parameters, and an intensive computation using the direct simulation Monte Carlo method was then performed to simulate the Couette flows between two walls for different gas, number density, wall (plate) velocity, wall temperature, and distance between the two walls.
Abstract: A qualitative analysis is first carried out to determine the slip coefficient as a function of two dimensionless parameters. An intensive computation using the direct simulation Monte Carlo method is then carried out to simulate the Couette flows between two walls for different gas, number density, wall (plate) velocity (Uw), wall temperature (Tw) and distance between the two walls. Numerical results show that the slip coefficient is proportional to the mean free path gw of molecules colliding with the wall, which is affected by the number density, the wall temperature and gas mass. The slip coefficient is finally found to be 1.125 gw. This slip coefficient is verified for five gases, and validated under the conditions of Uw300 m s-1 and Tw500 K. This slip coefficient is very useful for slip flow analysis in micro-electro-mechanical systems using N-S equations.
63 citations
TL;DR: In this article, the authors proposed a new scheme to enhance vehicle lateral stability with a traction control system during cornering and lane changes by varying the slip ratio as a function of the slip angle.
Abstract: Traction control systems are used to prevent wheel slippage and to maximize traction forces. This paper proposes a new scheme to enhance vehicle lateral stability with a traction control system during cornering and lane changes. This scheme controls wheel slip during cornering by varying the slip ratio as a function of the slip angle. It assumes that a traction control system with the engine throttle angle is used. The scheme is dynamically simulated with a model of front-wheel-driven passenger vehicles. Simulation results show that the proposed scheme is robust and superior to a conventional one, which is based upon fixed slip ratios, during cornering and lane changes.
52 citations
Patent•
08 Apr 1999TL;DR: In this article, a mathematical tire model of each wheel defining a relationship between longitudinal and lateral forces vs. slip ratio is synthesized at zero slip and a control input from an outside running behavior controller such as a spin controller or a driftout controller to generate nominal values of longitudinal force, lateral force and yaw moment of the vehicle body.
Abstract: A control device for controlling the running behavior of a four wheeled vehicle has a mathematical tire model of each wheel defining a relationship between longitudinal and lateral forces vs. slip ratio, synthesizes the mathematical tire model at zero slip and a control input from an outside running behavior controller such as a spin controller or a driftout controller to generate nominal values of longitudinal force, lateral force and yaw moment of the vehicle body, and controls the slip ratio of the wheels through cyclic adjustment so as to approach the differences between the nominal values and the actual values in the longitudinal force, lateral force and yaw moment of the vehicle body to the corresponding differences of those parameters due to differentiation thereof by the slip ratio based upon the mathematical tire model.
39 citations
TL;DR: In this paper, a model for predicting pressure losses in foams of various expansions and pressures, in pipes of any given diameter, once the foam behavior has been characterized at a single expansion and pressure.
Abstract: This paper presents a model for predicting pressure losses in foams of various expansions and pressures, in pipes of any given diameter, once the foam behavior has been characterized at a single expansion and pressure. The model incorporates a modified form of the power-law viscosity model of foam, which is obtained through the method of volume equalization. Since apparent wall slip contributes significantly to pipe flow of foam, the wall slip also needs to be characterized to enable predictions of pressure losses. The couplings between foam flow and wall slip characteristics are investigated, and two models are presented to predict slip velocities for slow and fast flow rates. Experimentally we find that uslip ∝ ∈-3/2, where ∈ denotes the foam expansion ratio at the experimental pressure. Predicted results are compared with experimental observations, with good agreement.
35 citations
TL;DR: In this article, a high-pressure sliding plate rheometer was used to investigate the flow behavior of polyisobutylene in simple shear, and it was found that wall slip is a dominant feature of the flow at the pressures, temperatures, and rates of deformation typically found in the processing of elastomers.
Abstract: A high-pressure sliding plate rheometer was used to investigate the flow behavior of polyisobutylene in simple shear. Experiments carried out using smooth steel surfaces revealed that wall slip is a dominant feature of the flow at the pressures, temperatures, and rates of deformation typically found in the processing of elastomers. A set of grooved plates made it possible to obtain viscosity data at stresses up to 20 kPa, but at higher stresses, the sample “slipped” even on the grooved plates. These data were fitted to a Cross viscosity model and extrapolated in order to estimate the viscosity at higher stresses. Flow curves (shear stress versus nominal shear rate) generated using fluoroelastomer–steel and steel–steel pairs of plates exhibited four distinct flow regimes: no-slip, adhesive slip, mixed adhesive, and cohesive slip, and primarily cohesive slip. Slip velocities were calculated by comparing the no-slip stresses estimated using the Cross model with measured values. The effect of pressure on cohesive wall slip was found to scale with pressure in the same way as viscosity, while the effect of pressure on adhesive wall slip did not.A high-pressure sliding plate rheometer was used to investigate the flow behavior of polyisobutylene in simple shear. Experiments carried out using smooth steel surfaces revealed that wall slip is a dominant feature of the flow at the pressures, temperatures, and rates of deformation typically found in the processing of elastomers. A set of grooved plates made it possible to obtain viscosity data at stresses up to 20 kPa, but at higher stresses, the sample “slipped” even on the grooved plates. These data were fitted to a Cross viscosity model and extrapolated in order to estimate the viscosity at higher stresses. Flow curves (shear stress versus nominal shear rate) generated using fluoroelastomer–steel and steel–steel pairs of plates exhibited four distinct flow regimes: no-slip, adhesive slip, mixed adhesive, and cohesive slip, and primarily cohesive slip. Slip velocities were calculated by comparing the no-slip stresses estimated using the Cross model with measured values. The effect of pressure on cohe...
TL;DR: In this article, the effect of the slip coefficient and the mobility capillary number on the spreading of a thin axisymmetric liquid droplet with uniform heating/cooling of the solid surface is examined.
Abstract: The effect of the slip coefficient and the mobility capillary number on the spreading of a thin axisymmetric liquid droplet with uniform heating/cooling of the solid surface is examined. The results show that increasing the slip coefficient reduces the spreading/shrinking behavior of the droplet and that the final equilibrium states are slip dependent. These results are explained by the development of a return flow inside the droplet. We show how a speed-dependent slip coefficient can be used to remove the dependence of the final state on the slip coefficient. It is also shown that increasing the mobility capillary number decreases the spreading/shrinking rate of the droplet. For thermocapillary-driven droplets, there is a capillary-number-dependent time delay for the onset of motion. The entire effect of the mobility capillary number on the spreading process is explained in terms of the deformability of the free surface.
TL;DR: In this article, it was shown that an increasing dependence of the slip velocity on the elastic normal stress in the flow direction leads to short wavelength flow instability at sufficiently high Weissenberg number (≳10).
Abstract: We show that for shear flow of an upper convected Maxwell fluid with small but nonzero slip velocity, an increasing dependence of the slip velocity on the elastic normal stress in the flow direction leads to short wavelength flow instability at sufficiently high Weissenberg number (≳10). Pressure-dependent slip can also lead to instability, but only at unrealistically large Weissenberg number. If the slip velocity depends only on shear stress, then the flow is always stable. These analytical results are valid in a specific asymptotic limit, but are independent of the specific form of the model for slip. Numerical results for specific, phenomenological slip models and the Phan-Thien–Tanner bulk constitutive model show that the results are robust in the presence of nonlinear viscoelasticity. The scaling of the critical shear stress for instability with modulus and molecular weight and of the distortion period with polymer relaxation time are qualitatively consistent with experimental observations of the sharkskin instability in linear polyethylenes. The results may also have some relationship to the recent experimental observation of short wavelength instability in plane Couette flow of an entangled solution with wall slip.
TL;DR: In this paper, a selection of experimental measurements for He-Ar, He-N2, and He-Ne binary gas mixtures which were made with a spinning rotor gauge (SRG) are reported.
Abstract: A selection of experimental measurements for He-Ar, He-N2, and He-Ne binary gas mixtures which were made with a spinning rotor gauge (SRG) are reported. All of the experiments were conducted in the slip regime. Theoretical results from a previous paper on the SRG are used to extract values of the viscosity and the velocity slip coefficient from the experimentally obtained data for each of the gas mixtures. The measured viscosities are in excellent agreement with existing literature values. Slip coefficients for binary gas mixtures have not previously been reported. An important issue here is whether the velocity slip coefficients for binary gas mixtures can be predicted accurately using separately measured tangential momentum accommodation coefficients. The calculation of slip coefficients from theory requires a knowledge of the accommodation coefficients of each constituent of the mixture. The dependence of these coefficients on the gas composition is not known and the simplest assumption is to regard th...
TL;DR: In this article, a method for predicting the mass transfer coefficient as well as the limiting permeate flux in membrane ultrafiltration has been found, based upon the boundary-layer theory which takes into account the slip velocity on the membrane surface.
TL;DR: In this paper, an experimental technique for the measurement of the local slip velocity of spherical bubbles is reported, which is based on measurement of local liquid velocity by an electrodiffusional method, and the bubble velocity by a specially adapted LDA (Laser Doppler anemometer) with a short measuring volume.
Abstract: An experimental technique for the measurement of the local slip velocity of spherical bubbles is reported. It is based on the measurement of the local liquid velocity by an electrodiffusional method, and the bubble velocity by a specially adapted LDA (Laser Doppler anemometer) with a short measuring volume. The bubble velocity is measured taking into account the shift between the bubble centre and the centre of the LDA measuring volume. The slip velocity is obtained by subtracting the liquid velocity from the bubble velocity at the point corresponding to the bubble centre. The technique is applicable for flows with high velocity gradients. Results of the slip velocity measurements in an upward bubbly flow at laminar pipe Reynolds numbers are presented.
Patent•
22 Dec 1999TL;DR: In this article, a mathematical tire model of each wheel defining a relationship between longitudinal and lateral forces vs. slip ratio is synthesized at zero slip and a control input from an outside running behavior controller such as a spin controller or a driftout controller to generate nominal values of longitudinal force, lateral force and yaw moment of the vehicle body, and controls the slip ratio of the wheels through cyclic adjustment.
Abstract: A control device for controlling the running behavior of a four wheeled vehicle has a mathematical tire model of each wheel defining a relationship between longitudinal and lateral forces vs. slip ratio, synthesizes the mathematical tire model at zero slip and a control input from an outside running behavior controller such as a spin controller or a driftout controller to generate nominal values of longitudinal force, lateral force and yaw moment of the vehicle body, and controls the slip ratio of the wheels through cyclic adjustment so as to approach the differences between the nominal values and the actual values in the longitudinal force, lateral force and yaw moment of the vehicle body to the corresponding differences of those parameters due to differentiation thereof by the slip ratio based upon the mathematical tire model, wherein when an uncontrollable braking force is applied to any one of the wheels due to a malfunction of the brake system, the nominal values of the longitudinal force and the yaw moment are modified to be decreased as much as an additional longitudinal force and an additional yaw moment corresponding respectively to a longitudinal force and a yaw moment generated in the vehicle by a difference between the uncontrollable braking force and a braking force to be applied to the one wheel according to the slip control.
TL;DR: In this paper, the authors proposed two novel traction control techniques of electric vehicle, i.e., the model following control and the optimal slip ratio control, which are demonstrated by simulation and by the real test vehicle "UOT Electric March".
TL;DR: In this paper, a non-monotonic slip equation relating the shear stress to the velocity at the wall was used to explain the instability of the Poiseuille flow of an Oldroyd-B fluid with slip along the wall.
Abstract: A mechanism for explaining some of the instabilities observed during the extrusion of polymer melts is further explored. This is based on the combination of non-monotonic slip and elasticity, which permits the existence of periodic solutions in viscometric flows. The time-dependent, incompressible, one-dimensional plane Poiseuille flow of an Oldroyd-B fluid with slip along the wall is studied using a non-monotonic slip equation relating the shear stress to the velocity at the wall. The stability of the steady-state solutions to one-dimensional perturbations at fixed volumetric flow rateis analyzed by means of a linear stability analysis and finite element calculations. Self-sustained periodic oscillations of the pressure gradient are obtained when an unstable steady-state is perturbed, in direct analogy with experimental observations.
Patent•
28 Sep 1999
TL;DR: In this paper, the authors proposed a method to prevent rapid reduction of brake liquid pressure through antiskid control by calculating a slip ratio based on a second estimated car body speed reduced at a given deceleration from a given value.
Abstract: PURPOSE:To prevent rapid reduction of a brake liquid pressure through antiskid control by calculating a slip ratio based on a second estimated car body speed reduced at a given deceleration from a given value when a first estimated car body speed is reduced to a very low car body lower than a given value. CONSTITUTION:In a controller 17, a first estimated car body speed is calculated by a means 30 based on a maximum wheel speed detected by wheel speed sensors 13 - 16 and deceleration detected by a G sensor 12. A second estimated car body speed, reduced at given deceleration from a given value and not influenced by the change of a maximum wheel speed, is calculated by a means 32. When the first estimated car body speed exceeds a given value, a first estimated car body speed is selected by a means 34 and when it is below the given value, the second estimated car body speed is selected thereby. Meanwhile, based on a selected estimated car body speed and wheel speed, the slip ratio of each wheel is calculated by a means 36. During braking, a brake force is controlled by a means 38 so that a calculated slip ratio is adjusted to a target value.
Patent•
10 Feb 1999TL;DR: In this paper, an antiskid brake controller (20) utilizes measured wheel speed in order to provide brake control for a vehicle such as an aircraft, and the controller estimates the speed of the vehicle via approximation based on the measured wheel speeds and a model of the mu-slip ratio curve representing the wheel to running surface friction characteristics.
Abstract: An antiskid brake controller (20) utilizes measured wheel speed in order to
provide brake control for a vehicle such as an aircraft. The controller (20) estimates
the speed of the vehicle via approximation based on the measured wheel speed and
a model of the mu-slip ratio curve representing the wheel to running surface friction
characteristics. The controller (20) then predicts the slip ratio based on the
measured wheel speed and estimated vehicle speed. The difference between the
predicted slip ratio and a predefined desired slip ratio is used to drive a modified
integral controller segment (56) to achieve maximum obtainable friction. In another
embodiment, the controller (20) measures and integrates the applied braking torque
in order to estimate the vehicle speed. The estimated vehicle speed is again
combined with the measured wheel speed to determine an estimated slip ratio. The
controller (20) compares the estimated slip ratio with a predefined desired slip ratio
which again drives a modified integral controller (56).
Patent•
08 Apr 1999
TL;DR: In this paper, the relation between the friction factor and slip ratio S of a tire is stored as an equation μ=(aSb-c)exp(-Sd)+c.exp(Se), where(a), (b), (c), (d), (e) are coefficients.
Abstract: PROBLEM TO BE SOLVED: To sharply reduce the number of prototypes by indicating the relation between the friction factor and slip ratio of a tire as a specific equation, determining coefficients from measured values, generating and referring an element technical table, and experimentally manufacturing and testing the experimental tire through simulation. SOLUTION: The relation between the friction factor μ and slip ratio S of a tire is stored as an equation μ=(aSb-c)exp(-Sd)+c.exp(Se), where(a), (b), (c), (d), (e) are coefficients (111). Relations between the friction factor μand slip ratio S of tires of many kinds are measured to determine the coefficients (a)-(e) (112, 114). An element technical table is generated from relations between the determined coefficients and the types of tires (114). Friction characteristics matched with development needs are determined by simulation in reference to the element technical table, and an experimental tire having the friction characteristics is experimentally manufactured and tested (117-119). Many prototypes are not required to be manufactured, and the development cost can be suppressed.
Patent•
02 Feb 1999
TL;DR: In this paper, a vehicular brake controller uses as a leg power detection switch a stoplight switch 2 for turning a stop light on when a brake pedal has been stepped on and turned, to detect the leg power to the pedal and the stepping speed, of which detected results are fed into a computer 7.
Abstract: PROBLEM TO BE SOLVED: To control the brakes of a vehicle properly so that they have a slip ratio suitable to road conditions. SOLUTION: A vehicular brake controller uses as a leg power detection switch a stoplight switch 2 for turning a stoplight on when a brake pedal 1 has been stepped on and turned, to thereby detect the leg power to the pedal 1 and the stepping speed, of which detected results are fed into a computer 7. The brake controller calculates vehicle deceleration and road conditions in plural stages with the computer 7 to realize a slip ratio suitable to the stage of the estimated vehicle deceleration and road conditions.
Patent•
17 May 1999TL;DR: In this article, a vehicle and engine control system uses closed loop control based on a desired and actual turbine speed ratio, or slip ratio, to guarantee positive torque applied to the transmission.
Abstract: A vehicle and engine control system controls engine torque to maintain positive torque at a transmission input to prevent the transmission gears from separating. By maintaining a positive engine torque, the transmission is prevented from operating in or through the zero torque, or lash, zone. This prevents poor vehicle driveability that would otherwise result from operation in the lash zone. The control systems uses closed loop control based on a desired and actual turbine speed ratio, or slip ratio, to guarantee positive torque applied to the transmission.
TL;DR: In this article, the effects of follower mass, time ratio, driver speed, and normal load on the slip displacement and stick-slip characteristics were experimentally and theoretically investigated in the reciprocating friction drive system under dry contact using a 0.45% carbon steel pair.
Patent•
06 Jul 1999
TL;DR: In this article, the starting condition of the control of distribution of the braking force is divided on the basis of the brake pedal depressing amount and speed or the like, and the judgement of a spike is set when the change is more than a specified value and a specified time has passed.
Abstract: PROBLEM TO BE SOLVED: To optimize the start of control of the distribution of the braking force by changing a threshold value on the basis of the depressing degree of a brake when the control of distribution of the braking force is started by controlling an inlet valve and an outlet valve of a rear wheel when the braking pedal is depressed and the estimated car deceleration or wheel deceleration is over the threshold value SOLUTION: The starting condition of the control of distribution of the braking force is divided on the basis of the brake pedal depressing amount and speed or the like (the change of estimated car deceleration or wheel deceleration), and the judgement of a spike (S21) A control start flag is set (S26) when the change is more than a specified value and a specified time has passed (the deressing is strong), and when the estimated deceleration is more than a specified value α1 as the result of the judgement whether the estimated deceleration is more than the specified value α or not (S22), and a slip ratio of a rear wheel is more than a specific value β1 (S23) The distribution control is started (S26) when the depressing is weak, the estimated deceleration is more than a specified value α2 as the result of the judgement whether the estimated deceleration is more than the specific value α2 (α2>α1) or not, and the slip ratio of the rear wheel to the front wheel is more than a specific value β2 (β2>β1) (S25) Whereby the starting time of the control of distribution of the braking force can be properly optimized
Patent•
19 Mar 1999
TL;DR: In this article, the ECU 100 computes a slip ratio SL of each wheel 11-14 on the basis of a car speed estimated based on each wheel speed and the real wheel speed.
Abstract: PROBLEM TO BE SOLVED: To prevent accidental ignition of an engine and the deterioration of emission by computing the slippage value of wheels, and when the slippage value exceeds the predetermined threshold value after starting the traveling by engine, controlling the engine for torque-reduction so as to converge the slip value to a target value. SOLUTION: At operation of a vehicle, an ECU 100 computes a slip ratio SL of each wheel 11-14 on the basis of a car speed estimated on the basis of each wheel speed and the real wheel speed, and computes a change ratio ΔSL of the slip obtained by differentiating the slip ratio SL. Discrimination is made as to whether or not the slip ratio SL exceeds a prescribed threshold SL0, and if 'YES', discrimination is made as to whether or not the change ratio ΔSL of the slip ratio exceeds the prescribed threshold ΔSL0. If 'YES' and in the case where a clutch 6 is turned on, control quantity of a traveling motor 2 and control quantity of an engine 1 are set by using a map in response to the required torque for torque-reduction, and the torque is reduced so as to converge the slip value to the target value.
TL;DR: In this article, a simulation model to calculate a slip length during thermal processes was proposed on the basis of dislocation kinetics, and the slip length was calculated by integrating the dislocation velocity by the duration of thermal processes.
Abstract: A simulation model to calculate a slip length during thermal processes was proposed on the basis of dislocation kinetics. The dislocation velocity was calculated from gravitational and thermal stresses. The slip length was calculated by integrating the dislocation velocity by the duration of thermal processes. It was found that the model could predict the slip length, the optimum ramping rate, and wafer spacing quantitatively with high accuracy for 300 mm wafers. © 1999 The Electrochemical Society. All rights reserved.
Patent•
09 Aug 1999
TL;DR: In this article, the authors proposed a method to find a slip angle irrespective of a road surface, by an inexpensive means not using an expensive sensor such as a master cylinder pressure sensor.
Abstract: PROBLEM TO BE SOLVED: To highly precisely find a slip angle irrespective of a road surface μ, by an inexpensive means not using an expensive sensor such as a master cylinder pressure sensor. SOLUTION: This detector is provided with an input means (a) for generating a signal as to a vehicle behavior, a slip ratio detecting means (b) for finding a slip ratio of a wheel based on the signal from the input means (a), a slip angle detecting means (c) for finding a slip angle of the wheel based on an input from the input means (a), a normalized slip ratio computing means (d) for finding a normalized slip ratio by dividing a present slip ratio by a preset linear slip ratio, a normalized slip angle computing means (e) for finding a normalized slip angle by dividing a present slip angle by a preset linear slip angle, and a vehicle condition estimating means (f) for estimating at least one out of braking force and side force based on the normalized slip ratio and the normalized slip angle.