Word Up! Directed motor action improves word learning [Abstract]

Can simple motor actions help people expand their vocabulary? Here we show that word learning depends on where students place their flash cards after studying them. In Experiment 1, participants learned the definitions of ”alien words” with positive or negative emotional valence. After studying each card, they placed it in one of two boxes (top or bottom), according to its valence. Participants who were instructed to place positive cards in the top box, consistent with Good is Up metaphors, scored about 10

Extending Elliptic Curve Chabauty to higher genus curves

We give a generalization of the method of "Elliptic Curve Chabauty" to higher genus curves and their Jacobians. This method can sometimes be used in conjunction with covering techniques and a modified version of the Mordell-Weil sieve to provide a complete solution to the problem of determining the set of rational points of an algebraic curve $Y$.Comment: 24 page

Lateral guidance of all-wheel steered multiple-articulated vehicles

Nowadays, roads are becoming more and more congested, resulting in increasing economic losses due to delays. One way to solve this problem is to persuade people use public transp ortation more frequently. To achieve this, public transportation has to be improved. One way to improve public transportation is to construct a new kind of vehicle that combines the advantages of both commuter busses and railroad vehicles. Such a vehicle could be an all-wheel steered multiple-articulated vehicle. In the city of Eindhoven in The Netherlands, a new kind of transportation system will be operational in the year 2003, which is based on such vehicles. To achieve a track following behaviour similar to railroad vehicles, these vehicles have to be equipped with a lateral guidance system for steering them along a prede¯ne d path. This thesis deals with the design of such a guidance system. To achieve good tracking performance, the guidance system has to be modelbased. Therefore, a dynamic vehicle model has been derived. This model describes the nonlinear planar dynamics of an all-wheel steered n-carriage multiple-articulated vehicle. To validate this model, its frequency responses have been compared with the frequency responses of a 125 degrees of freedom multi-body model. This comparison shows good performance between both models. In order to show that a dynamic vehicle model is required, a comparison has been made between the dynamic vehicle model and a model describing only the kinematics of the vehicle. The position of the vehicle with respect to the path to be followed is crucial for proper control and therefore a measurement method based on the utilization of rotation symmetric bar magnets is presented. These magnets are buried in the road. By utilizing the rotation symmetry, the position to the magnet can be determined independently of the measurement height and the strength of the magnet. One requirement is that two ¯eld components are measured. It is shown that the sensitivity of this method to slant of the magnet and/or vehicle can be reduced by using a second dual-axes ¯eld sensor instead of one. Validation measurements show that the distance to the magnet can be determined with about 2 cm accuracy with 90 slant of the magnet. The permanent magnets yield position information exclusively and only at discrete instances. For controller design, knowledge of the complete state of the vehicle is desirable. An extended Kalman ¯lter has been designed to obtain continuous estimates of this state. To keep the in°uence of varying vehicle parameters small, accelerometers are used as input of the Kalman ¯lter. The accelerometer o®sets, road banking angle and vehicle roll angle are estimated online, to reduce the e®ect of these parameters. The position information obtained from the permanent magnets is used to apply corrections to state predictions that are based on the accelerometer outputs. The discrete and asynchronous character of this position information has been dealt with by implementing the Kalman ¯lter in a multi-rate fashion. Articulation angle sensors, wheel encoders and rate gyros are added to the Kalman ¯lter to improve the performance and to obtain redundan cy of sensors. The vehicles that will be used in the public transportation system in Eindhoven have, apart from all-wheel steering, also independent electrical drives on each of the wheels, except the two wheels at the front. This independent drive can in principle also be used for steering the vehicle, by using the drives on one axle in a di®erential way. A singular value analysis shows that steering with normal steering angles is much more in°uential than using these di®erential torques. It has also been analyzed that both at low and high speed all-wheel steering is bene¯cial to reduce o®-tracking of the rear axles and to improve the yaw dynamics of the vehicle. Two di®erent controllers have been designed for steering the vehicle, based on the outputs of the Kalman ¯lter, along the path to be followed. The ¯rst of these controllers is a feedback linearizing controller. This controller can be considered to consist of two control loops. The inner loop linearizes the planar vehicle dynamics, under the assumption that the steering system dynamics can be neglected. The outer control loop is used to counteract parameter uncertainty and disturbances. For this outer loop, a PID controller has been used. The second controller is a so-called backsteppin g controller. With this controller, also the steering actuator dynamics are taken into account. To simulate the behavior of the lateral guidance system, a more complex vehicle model has been used. This model describes besides the planar vehicle dynamics also the dynamics of the susp ension system. A nonlinear tire model has been used in this model. Simulations with this 3D simulation model show good tracking performance for both the feedback linearizing controller and the backstepping controller. The backstepping controller shows improved tracking performance compared to the feedback linearizing controller. However, this goes at the cost of increased high frequent behavior or the lateral acceleration

Equilibrium states for potentials with \sup\phi - \inf\phi < \htop(f)

In the context of smooth interval maps, we study an inducing scheme approach to prove existence and uniqueness of equilibrium states for potentials $\phi$ with he `bounded range' condition \sup \phi - \inf \phi < \htop, first used by Hofbauer and Keller. We compare our results to Hofbauer and Keller's use of Perron-Frobenius operators. We demonstrate that this `bounded range' condition on the potential is important even if the potential is H\"older continuous. We also prove analyticity of the pressure in this context.Comment: Added Lemma 6 to deal with the disparity between leading eigenvalues and operator norms. Added extra references and corrected some typo

Lateral guidance of all-wheel steered multiple-articulated vehicles

Nowadays, roads are becoming more and more congested, resulting in increasing economic losses due to delays. One way to solve this problem is to persuade people use public transp ortation more frequently. To achieve this, public transportation has to be improved. One way to improve public transportation is to construct a new kind of vehicle that combines the advantages of both commuter busses and railroad vehicles. Such a vehicle could be an all-wheel steered multiple-articulated vehicle. In the city of Eindhoven in The Netherlands, a new kind of transportation system will be operational in the year 2003, which is based on such vehicles. To achieve a track following behaviour similar to railroad vehicles, these vehicles have to be equipped with a lateral guidance system for steering them along a prede¯ne d path. This thesis deals with the design of such a guidance system. To achieve good tracking performance, the guidance system has to be modelbased. Therefore, a dynamic vehicle model has been derived. This model describes the nonlinear planar dynamics of an all-wheel steered n-carriage multiple-articulated vehicle. To validate this model, its frequency responses have been compared with the frequency responses of a 125 degrees of freedom multi-body model. This comparison shows good performance between both models. In order to show that a dynamic vehicle model is required, a comparison has been made between the dynamic vehicle model and a model describing only the kinematics of the vehicle. The position of the vehicle with respect to the path to be followed is crucial for proper control and therefore a measurement method based on the utilization of rotation symmetric bar magnets is presented. These magnets are buried in the road. By utilizing the rotation symmetry, the position to the magnet can be determined independently of the measurement height and the strength of the magnet. One requirement is that two ¯eld components are measured. It is shown that the sensitivity of this method to slant of the magnet and/or vehicle can be reduced by using a second dual-axes ¯eld sensor instead of one. Validation measurements show that the distance to the magnet can be determined with about 2 cm accuracy with 90 slant of the magnet. The permanent magnets yield position information exclusively and only at discrete instances. For controller design, knowledge of the complete state of the vehicle is desirable. An extended Kalman ¯lter has been designed to obtain continuous estimates of this state. To keep the in°uence of varying vehicle parameters small, accelerometers are used as input of the Kalman ¯lter. The accelerometer o®sets, road banking angle and vehicle roll angle are estimated online, to reduce the e®ect of these parameters. The position information obtained from the permanent magnets is used to apply corrections to state predictions that are based on the accelerometer outputs. The discrete and asynchronous character of this position information has been dealt with by implementing the Kalman ¯lter in a multi-rate fashion. Articulation angle sensors, wheel encoders and rate gyros are added to the Kalman ¯lter to improve the performance and to obtain redundan cy of sensors. The vehicles that will be used in the public transportation system in Eindhoven have, apart from all-wheel steering, also independent electrical drives on each of the wheels, except the two wheels at the front. This independent drive can in principle also be used for steering the vehicle, by using the drives on one axle in a di®erential way. A singular value analysis shows that steering with normal steering angles is much more in°uential than using these di®erential torques. It has also been analyzed that both at low and high speed all-wheel steering is bene¯cial to reduce o®-tracking of the rear axles and to improve the yaw dynamics of the vehicle. Two di®erent controllers have been designed for steering the vehicle, based on the outputs of the Kalman ¯lter, along the path to be followed. The ¯rst of these controllers is a feedback linearizing controller. This controller can be considered to consist of two control loops. The inner loop linearizes the planar vehicle dynamics, under the assumption that the steering system dynamics can be neglected. The outer control loop is used to counteract parameter uncertainty and disturbances. For this outer loop, a PID controller has been used. The second controller is a so-called backsteppin g controller. With this controller, also the steering actuator dynamics are taken into account. To simulate the behavior of the lateral guidance system, a more complex vehicle model has been used. This model describes besides the planar vehicle dynamics also the dynamics of the susp ension system. A nonlinear tire model has been used in this model. Simulations with this 3D simulation model show good tracking performance for both the feedback linearizing controller and the backstepping controller. The backstepping controller shows improved tracking performance compared to the feedback linearizing controller. However, this goes at the cost of increased high frequent behavior or the lateral acceleration

The Dolgopyat inequality in bounded variation for non-Markov maps

This is the author accepted manuscript. The final version is available from World Scientific via the DOI in this record.Let F be a (non-Markov) countably piecewise expanding interval map satisfying certain regularity conditions, and Ł˜Ł̃ the corresponding transfer operator. We prove the Dolgopyat inequality for the twisted operator Ł˜s(v)=Ł˜s(esφv)Ł̃s(v)=Ł̃s(esφv) acting on the space BV of functions of bounded variation, where φφ is a piecewise C1C1 roof function.We are also grateful for the support the Erwin Schrodinger Institute in Vienna, where this paper was completed

Complex maps without invariant densities

We consider complex polynomials $f(z) = z^\ell+c_1$ for $\ell \in 2\N$ and $c_1 \in \R$, and find some combinatorial types and values of $\ell$ such that there is no invariant probability measure equivalent to conformal measure on the Julia set. This holds for particular Fibonacci-like and Feigenbaum combinatorial types when $\ell$ sufficiently large and also for a class of `long-branched' maps of any critical order.Comment: Typos corrected, minor changes, principally to Section

Natural equilibrium states for multimodal maps

This paper is devoted to the study of the thermodynamic formalism for a class of real multimodal maps. This class contains, but it is larger than, Collet-Eckmann. For a map in this class, we prove existence and uniqueness of equilibrium states for the geometric potentials $-t \log|Df|$, for the largest possible interval of parameters $t$. We also study the regularity and convexity properties of the pressure function, completely characterising the first order phase transitions. Results concerning the existence of absolutely continuous invariant measures with respect to the Lebesgue measure are also obtained