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The vortex tube can separate a mass flow into a hot and cold mass flow. In this paper, the energy balance in the boundary layer of the vortex tube is analyzed with respect to a possible effect of temperature separation in the boundary layer by the viscous term of the enthalpy balance equation. A Large Eddy Simulation is used to generate the velocity profiles used for the computation of the viscous source terms. The dominant contributions of the source terms in the boundary layer of the vortex tube are identified and computed from the velocity fields. It is demonstrated how the strong velocity gradients in the boundary layer create a viscous flux of energy. An implementation of balance equations both with and without source term show the effect of energy separation in the boundary layer of the vortex tube.
In today's AI-driven era, computer vision, including autonomous driving, robotics, and healthcare, is prevalent. How-ever, acquiring ample data while managing resources and privacy constraints is challenging. This article proposes a solution: synthetic data generation. We use CAD software to craft intricate 3D models, process them in Blender, and evaluate quality using metrics like Structural Similarity and PSNR (Peak Signal to Noise Ratio). Synthetic data achieves up to 90% similarity with real data and an average PSNR of 21dB. Our method offers a streamlined, dependable ap-proach for enhancing computer vision, especially in object detection, addressing data acquisition challenges.
The power density of electric machines is a critical factor in various applications, i.e. like the power train. A major factor to improve the power density is boosting the electric current density, which increases the losses in the limited volume of the electric machine. This results in a need for an optimized thermal design and efficient cooling. The dissipation of heat can be achieved in a multitude of ways, ranging from air cooling to highly integrated cooling solutions. In this paper, this variety is shown and analyzed with a focus on water cooling. Further various structures in electric machines are presented.
A planar testbench is built to systematically analyze water cooling geometries. The focus lies in providing different power loss distributions along cooling channels, accurate temperature readings in a multitude of locations, as well as the pressure drop across the channel. The test bench results are aligned with simulations and simplified analytical evaluation to support the development process.
The main goal in this paper is to determine temperature gradients in the material close to the stator to quantize the potential for future cooling jacket designs. One question ,to answer is: How large the gradient is considering a realistic power loss distribution. Another sensible point are the different thermal expansions of aluminum used in cooling jackets and the steel core of the stator. This can be bypassed by using a steel cooling jacket. In this case, the performance of a steel cooling jacket compared to an aluminum version is investigated and also if light weight construction can compensate the lower thermal conductivity of steel.
After the analysis, an outlook about future changes of the measurement methods are given and first potentials for future cooling jackets are proposed.
In this thesis a swarm intelligent approach for controlling and coordinating a multi- agent system is studied. Considering an example where bodyguard agents have to protect one or more VIP agents, it is shown that the swarm intelligent approach can be a flexible and robust way to control a multi-agent system.
Globalization has not only changed our society, it has also had a profound effect on education. Many schools deal with student populations which, due to migration, are increasingly multilingual. Politically, few argue against the importance of multilingualism; rather, it is promoted. However, in practical terms the challenges associated with teaching and educational policies have increased as a result of linguistic diversity among student bodies. Moreover, reading is certainly regarded as a key learning skill, but how is the students’ life-world multilingualism (LWMUL) taken into consideration? Previous research suggests that there are significant links between teachers’ beliefs and practices, making this a compelling issue. The overall aim of this study was thus to gain a deeper understanding on teachers’ beliefs and strategies when teaching reading in multilingual settings. Using a cross-disciplinary, qualitative research methodology approach, the empirical inquiry consists of case studies with different, linguistically diverse settings. The case studies include classroom observations as well as teacher interviews in German, Swedish and Chilean grade 4 classrooms. After a qualitative content analysis in three analysis procedures, the results suggest dualistic beliefs being exhibited by the teachers. The separation of languages is believed to be of major importance, thus providing space almost exclusively for the academic language of instruction. This is reflected in the teachers’ strategies, leading to a static implementation, in which the students’ life-world multilingual resources (MULR) are generally not included. A lack of professional competence could be observed in issues regarding multilingualism, allowing beliefs rather than evidence-based knowledge to be the deciding factor in the practice. Four types of strategies for teaching reading in multilingual settings were identified, and an inattentive type of strategy, including a blindness to difference, seems to dominate.