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We present a novel measurement method for the characterization of thermal diodes in a saturated steam atmosphere. A measuring setup has been developed in which two pressure sensors are integrated. Using a developed analytical model, the heat flow, the volume flow, and the cracking pressure are determined from the measured absolute pressures and the pressure difference. The analytical model was verified using a flow through an orifice. We first calculated the volume flow through the orifice, with a diameter of 3 mm, using the Reader-Harris equation and then compared it to experimentally determined values. The experimentally determined values showed a discrepancy of 9%. With the measurement setup, we have characterized a check valve developed for magnetocaloric heat pumps, which has a thermally rectifying behavior. The developed check valve consists of three spring arms, which are radially attached to a valve disk. The heat flow through the check valve in the forward direction is 166 W for water, 239 W for ethanol, and 547 W for methanol at a temperature difference of 1 K. In the reverse direction, the heat flow is −0.03 W at a temperature difference of −1 K. For methanol, this corresponds to a rectification coefficient of more than 18 000.

Cooling with caloric materials could be an option to replace compressor-based cooling systems in the future. In addition to the advantage of avoiding dangerous liquid coolants, one often cites a possible higher efficiency of the calorific cooling systems compared to compressor-based systems. But is that true? The aim of this work is to assess the efficiency potential of caloric cooling systems on a very basic material level. We placed our focus on materials with a first-order phase change since they generally show a large caloric response. We derive a relation between thermal hysteresis and the dissipative losses due to hysteresis. To predict the efficiency, this relation is integrated in a Carnot-like cycle. This approach was chosen to get access to the efficiency reduction due to hysteresis without any further losses due to other nonidealities of the thermodynamic cycle. As a main finding, we present a direct relation between thermal hysteresis and the expected maximum exergy or second-law efficiency of a caloric cooling device. These results indicate that, for many caloric materials, the thermal hysteresis needs to be further reduced to be able to compete with the efficiency of compressor-based systems.

In order to predict the potential of magnetocaloric heating and cooling devices, system simulations are an essential instrument. These simulations, in turn, depend to a large extent on the model implemented for the magnetocaloric material. Magnetocaloric materials with a first-order phase transition, such as found in some La(Fe,Mn,Si)13-based alloys, show excellent magnetocaloric properties. The aim of this work is thus to provide a material model for a first-order La(Fe,Mn,Si)13-based alloy. The model is tailored to be used in system simulations. This includes thermodynamic consistency of the model and a relatively simple implementation. All relevant equations of the material model are determined from the specific heat capacitance as function of the temperature and the magnetic field. Since all equations are derived from the same base equation, they are consistent in terms of the first and second law of thermodynamics. As base function for the specific heat capacitance, a modified Cauchy-Lorentz function is used. The model parameters are determined from experimental data. Consistency of the model is verified with further data. The present model enables the simulation of the exergetic efficiency of a magnetocaloric cooling or heating device based on first-order La(Fe,Mn,Si)13 alloys.

Kinematic approaches of motion generation use joint angles of a specified kinematic skeleton to describe poses and consider motions as sequences of poses. The progression functions, i.e. the functions describing the angular values of the joints over time are usually obtained by motion capturing. So far, approaches to synthesize these functions have only been able to create motions with strong artificial visual appearance. In this paper we present a novel method for generating gait motions from synthesized progression functions. Our method is based on the key observation that the progression functions of the joints involved in gait motions show certain characteristic shapes. Based on empirical evaluations we describe these shapes for all progression functions needed to generate walking movements. Furthermore, we analyze the variation of the described shapes depending on stride length and walking speed. Polynomial splines are used to define functions that mimic the shapes of progression functions and can be easily controlled via the spline parameters. We develop a model that describes how to change the parameters of the splines according to the rules of shape variation observed on empirical data in order to adjust stride length and walking speed. Our method can be used to generate walking motions of virtual characters with user provided stride length or walking speed. To evaluate our method we compare synthesized gait motions with recorded ones. A numerical evaluation shows that the maximal joint displacement between captured and synthesized motions lies within the range of variability of natural human walking.

Solid state cooling based on caloric materials has a large potential, because there is no need for fluid refrigerants. The state of the art system approach relies on a heat transfer fluid, which is pumped back and forth through a regenerator of caloric material. This system approach has fundamental limitations regarding the cycle frequency. Different system approaches are considered. One is the utilization of fast thermal diodes or switches. The aim of this work is to provide a universal model to describe a cooling system based on caloric materials using thermal diodes or switches. The heat capacitance of the caloric material is defined to be constant, allowing a lumped elements representation. An analytical model based on an analogy to an electrical low pass filter is introduced. The analytical model is compared with good agreement to lumped elements simulations and measurement data from the literature. It is shown, that the newly introduced cut-off frequency as merit for the potential cycle frequency is proportional to the heat transfer coefficient of the diodes/switches in flux direction and inverse proportional to the length scale of the caloric material in heat flux direction. Different heat transfer mechanisms are discussed as basis for such thermal diodes and switches in combination with different caloric effects. To increase the cycle frequency compared to state of the art systems, latent heat transfer is a promising candidate for all caloric effects, whereas for example a dry press contact for a magnetocaloric system presents many challenges.