Propulsive Battery Packs Sizing for Aviation Applications

This thesis derives analytical methods for sizing the propulsive battery packs for designing an electric-driven aircraft. Lithium-Ion (Li-Ion) battery is the primary choice of battery cell chemistry in this thesis research due to its superior specific energy and market availability. The characteristics of Lithium-Ion battery cells are first determined and studied using experimental test results and manufacturers published data. Based on the design requirement to the battery system, the battery sizing will fall into one of the two sizing categories. The first category is power sizing, which requires the battery’s ability to deliver full power demanded by the electric motor. The second category is endurance sizing, which requires the battery system to store sufficient energy for the required endurance. Both types of sizing are analytically derived. From the sizing result, capacity is used to determine the parallel connected battery cells. The required system voltage governs the series connected cells. A battery discharging simulation model is built to validate the sizing results

Development of Rapid Robotic Fish based on Smart Material Actuators

The main objective of this project is to build and test a rapid robotic fish with its propulsion system based on smart material actuators, such as Macro Fiber Composites (MFC) and Ionic Polymer Metal Composites (IPMC). These state-of-the-art actuators based on active materials offer several potential advantages for robotic fish applications compared to traditional servo motors. One important benefit is that smart actuators are lightweight and can be embedded directly into the structure of a fish torso or control surface. In addition, they are eco-friendly and are completely green. Our goal is therefore to fabricate a fast fish-like robot swimming using biometric fish locomotion using MFCs and IPMCs. MFCs and IPMCs can be used as a main propulsion system, caudal fin, since it yields relatively high blocking force and it can bend significantly by controlling the amount of voltage applied to the actuators. These material characteristics will enable the robotic fish to replicate underwater fish movement. In order to fabricate fastest fish possible, the shape of the robotic fish also has to be similar to real fast underwater fish, which the tuna fish is chosen for this project. Tuna fish is not only the third fastest fish in the world but also its large torso can contain all necessary electronic components to provide enough power to the robotic fish. There has been some previous researches developing different types of robotic fish; however, fabricating a fastest robotic fish based on smart materials is a fairly new research area and we have been very interested in building one and testing it in the nonlinear waves lab located in the college of engineering. For this rapid robotic fish, the motion control can be achieved by wired connections for the first prototype. The module will control yawing and pitching of the fish. The body and tail portion of the fish will be made using frame and heat shrink films since it provides necessary internal space and demanding rigidity. The main propulsion in the tail will be controlled by one or two or three MFC bimorph actuators. The MFCs will bend the fish tail mimicking the motion of real tuna fish. Once this research has accomplished, it can be used as an application platform to unfold series of marine and robotic researches. Our project will be done combining multi-disciplinary areas including Applied Mathematics (generate fish motion equation), Materials (composites application), Structures, Fluid Dynamics (hydrostatic prediction and propulsion calculation) and Bionics (analyzing the motion of real-world sea creatures to improve our design). The main objective of this project is to build and test a rapid robotic fish with its propulsion system based on smart material actuators, such as Macro Fiber Composites (MFC) and Ionic Polymer Metal Composites (IPMC). These state-of-the-art actuators based on active materials offer several potential advantages for robotic fish applications compared to traditional servo motors. One important benefit is that smart actuators are lightweight and can be embedded directly into the structure of a fish torso or control surface. In addition, they are eco-friendly and are completely green. Our goal is therefore to fabricate a fast fish-like robot swimming using biometric fish locomotion using MFCs and IPMCs. MFCs and IPMCs can be used as a main propulsion system, caudal fin, since it yields relatively high blocking force and it can bend significantly by controlling the amount of voltage applied to the actuators. These material characteristics will enable the robotic fish to replicate underwater fish movement. In order to fabricate fastest fish possible, the shape of the robotic fish also has to be similar to real fast underwater fish, which the tuna fish is chosen for this project. Tuna fish is not only the third fastest fish in the world but also its large torso can contain all necessary electronic components to provide enough power to the robotic fish. There has been some previous researches developing different types of robotic fish; however, fabricating a fastest robotic fish based on smart materials is a fairly new research area and we have been very interested in building one and testing it in the nonlinear waves lab located in the college of engineering. For this rapid robotic fish, the motion control can be achieved by wired connections for the first prototype. The module will control yawing and pitching of the fish. The body and tail portion of the fish will be made using frame and heat shrink films since it provides necessary internal space and demanding rigidity. The main propulsion in the tail will be controlled by one or two or three MFC bimorph actuators. The MFCs will bend the fish tail mimicking the motion of real tuna fish. Once this research has accomplished, it can be used as an application platform to unfold series of marine and robotic researches. Our project will be done combining multi-disciplinary areas including Applied Mathematics (generate fish motion equation), Materials (composites application), Structures, Fluid Dynamics (hydrostatic prediction and propulsion calculation) and Bionics (analyzing the motion of real-world sea creatures to improve our design)

ViP3D: End-to-end Visual Trajectory Prediction via 3D Agent Queries

Existing autonomous driving pipelines separate the perception module from the prediction module. The two modules communicate via hand-picked features such as agent boxes and trajectories as interfaces. Due to this separation, the prediction module only receives partial information from the perception module. Even worse, errors from the perception modules can propagate and accumulate, adversely affecting the prediction results. In this work, we propose ViP3D, a visual trajectory prediction pipeline that leverages the rich information from raw videos to predict future trajectories of agents in a scene. ViP3D employs sparse agent queries throughout the pipeline, making it fully differentiable and interpretable. Furthermore, we propose an evaluation metric for this novel end-to-end visual trajectory prediction task. Extensive experimental results on the nuScenes dataset show the strong performance of ViP3D over traditional pipelines and previous end-to-end models.Comment: Project page is at https://tsinghua-mars-lab.github.io/ViP3

Stability of stope structure under different mining methods

The ore body has a great influence on the stability of surrounding rock and mining safety under different mining modes, and the reasonable selection of mining mode depends on other characteristics, such as ore structure surface feature, rock mass mechanical property, and ground stress distribution. Given the insufficient mining research data, this study establishes a 3D model by using the FLAC3D calculation program. Through numerical simulation and other technical means, a preliminary study on plastic and minimum stress changes during horizontal pillar mining, stress changes under different mining modes, and the effect comparison of full filling mining modes is conducted. Results show that the surrounding rock at the corner of pillar 1 is damaged, the plastic zone decreases, and the minimum stress in each working procedure increases slightly. The area of the plastic zone in alternate mining is smaller to that in continuous mining. This study provides a theoretical basis for ore body mining

On Uni-Modal Feature Learning in Supervised Multi-Modal Learning

We abstract the features (i.e. learned representations) of multi-modal data into 1) uni-modal features, which can be learned from uni-modal training, and 2) paired features, which can only be learned from cross-modal interactions. Multi-modal models are expected to benefit from cross-modal interactions on the basis of ensuring uni-modal feature learning. However, recent supervised multi-modal late-fusion training approaches still suffer from insufficient learning of uni-modal features on each modality. We prove that this phenomenon does hurt the model's generalization ability. To this end, we propose to choose a targeted late-fusion learning method for the given supervised multi-modal task from Uni-Modal Ensemble(UME) and the proposed Uni-Modal Teacher(UMT), according to the distribution of uni-modal and paired features. We demonstrate that, under a simple guiding strategy, we can achieve comparable results to other complex late-fusion or intermediate-fusion methods on various multi-modal datasets, including VGG-Sound, Kinetics-400, UCF101, and ModelNet40

Spatial Pathomics Toolkit for Quantitative Analysis of Podocyte Nuclei with Histology and Spatial Transcriptomics Data in Renal Pathology

Podocytes, specialized epithelial cells that envelop the glomerular capillaries, play a pivotal role in maintaining renal health. The current description and quantification of features on pathology slides are limited, prompting the need for innovative solutions to comprehensively assess diverse phenotypic attributes within Whole Slide Images (WSIs). In particular, understanding the morphological characteristics of podocytes, terminally differentiated glomerular epithelial cells, is crucial for studying glomerular injury. This paper introduces the Spatial Pathomics Toolkit (SPT) and applies it to podocyte pathomics. The SPT consists of three main components: (1) instance object segmentation, enabling precise identification of podocyte nuclei; (2) pathomics feature generation, extracting a comprehensive array of quantitative features from the identified nuclei; and (3) robust statistical analyses, facilitating a comprehensive exploration of spatial relationships between morphological and spatial transcriptomics features.The SPT successfully extracted and analyzed morphological and textural features from podocyte nuclei, revealing a multitude of podocyte morphomic features through statistical analysis. Additionally, we demonstrated the SPT's ability to unravel spatial information inherent to podocyte distribution, shedding light on spatial patterns associated with glomerular injury. By disseminating the SPT, our goal is to provide the research community with a powerful and user-friendly resource that advances cellular spatial pathomics in renal pathology. The implementation and its complete source code of the toolkit are made openly accessible at https://github.com/hrlblab/spatial_pathomics