Experimental and Numerical Study of a Mobile Reversible Air Conditioning-Heat Pump System

Electric vehicles suffer from range anxiety, while traditional resistive heating consumes a lot of electric energy and reduces EV drive range largely. Mobile reversible air conditioning-heat pump system is an energy efficient way of providing heat to EV cabin climate. In this paper, an AC/HP system was built based on the Nissan Leaf system configuration and experimentally studied. This system consists of three heat exchangers, an open-shaft compressor, two expansion valves, and two flow control valves. Heating performance of the system under various operating conditions was extensively investigated. Controlling subcooling was found a beneficial way of obtaining higher energy efficiency. Refrigerant charge imbalance when switching modes was found to be a challenge, and was studied both experimentally and numerically. Careful positioning of expansion valves, and sizing of liquid lines in both modes are essential in avoiding large charge imbalance. Component wise, the outdoor heat exchanger holds much more charge in AC mode than in HP mode. A steady state simulation model of the components and the system was developed and reasonably validated against experimental data. Options for improvement of the system based on modeling prediction were provided and discussed

Heteroepitaxial growth of ZnO branches selectively on TiO2 nanorod tips with improved light harvesting performance

A seeded heteroepitaxial growth of ZnO nanorods selectively on TiO2 nanorod tips was achieved by restricting crystal growth on highly hydrophobic TiO2 nanorod film surfaces. Intriguing light harvesting performance and efficient charge transport efficiency has been found, which suggest potential applications in photovoltaics and optoelectronics

Intermediate Vapor Bypass: A Novel Design for Mobile Heat Pump at Low Ambient Temperature

With market share of electric vehicles continue to grow, there is an increasing demand of mobile heat pump for cabin climate control, as it has much higher energy efficiency than electric resistive heating and hence much less impact on electric drive range. However, current mobile heat pump systems using low pressure refrigerant like R134a and R1234yf suffer from significant heating capacity loss at low ambient temperature. As a result, a large electric heater needs to be installed to supplement the capacity shortage at low ambient temperature, and electric drive range can be greatly reduced due to large power consumption for cabin heating. In this paper, the drop of heating capacity at low ambient temperature was experimentally and numerically studied. Pressure drop and refrigerant maldistribution in the outdoor heat exchanger in HP mode were found to be the most important factors. A novel design of the outdoor heat exchanger using intermediate vapor bypass in HP mode and the corresponding system architecture were proposed. The proposed outdoor heat exchanger turns into a condenser with integrated receiver and subcooler in A/C mode. A proof-of-concept heat exchanger prototype was made by modifying the baseline heat exchanger and tested in the lab. The result has shown 35% improvement of heating capacity at -20 ̊C ambient condition. Optimization of the outdoor heat exchanger design was investigated with a system model

Concept-free Causal Disentanglement with Variational Graph Auto-Encoder

In disentangled representation learning, the goal is to achieve a compact representation that consists of all interpretable generative factors in the observational data. Learning disentangled representations for graphs becomes increasingly important as graph data rapidly grows. Existing approaches often rely on Variational Auto-Encoder (VAE) or its causal structure learning-based refinement, which suffer from sub-optimality in VAEs due to the independence factor assumption and unavailability of concept labels, respectively. In this paper, we propose an unsupervised solution, dubbed concept-free causal disentanglement, built on a theoretically provable tight upper bound approximating the optimal factor. This results in an SCM-like causal structure modeling that directly learns concept structures from data. Based on this idea, we propose Concept-free Causal VGAE (CCVGAE) by incorporating a novel causal disentanglement layer into Variational Graph Auto-Encoder. Furthermore, we prove concept consistency under our concept-free causal disentanglement framework, hence employing it to enhance the meta-learning framework, called concept-free causal Meta-Graph (CC-Meta-Graph). We conduct extensive experiments to demonstrate the superiority of the proposed models: CCVGAE and CC-Meta-Graph, reaching up to $29\%$ and $11\%$ absolute improvements over baselines in terms of AUC, respectively

Advances In Surface Wave studies: 3D Wavefield Simulation Across East Asia and Imaging Shear Wave Anisotropic Structures Beneath Alaska

The development of computational tools and deployment of new and dense seismic arrays (e.g. USArray, ChinaArray) are accelerating the advancement of surface wave studies. Indeed, powerful numerical tools have made it feasible to perform wavefield simulation in 3D complex Earth&rsquo;s structures with high accuracy, and the seismic data collected by dense networks provide us unprecedented opportunity to infer the isotropic and anisotropic Earth&rsquo;s structures. The surface wave studies presented in this thesis are based on advanced computational techniques and high-quality seismic data. The thesis is organized in three parts, including 3D surface wavefield modelling and inferring shear wave anisotropic structures with surface waves. In the first part of the thesis, I simulate seismic wavefield propagation through a recent 3D crustal and upper mantle model of East Asia. I demonstrate that significant Rayleigh wave amplification downstream from sedimentary basins could be produced by elastic focusing of low velocity anomalies inside the basins. Understanding this amplification effect could help us better estimate earthquake source parameters. This is the first systematic study of the basin residual effects on short period through-passing surface waves. The second part of the thesis presents a model of the 3-D shear velocity structure of the crust and uppermost mantle beneath Alaska and surroundings, including crustal and mantle radial anisotropy. The model derives from a Bayesian Monte Carlo inversion of Rayleigh and Love wave dispersion data. The model captures several prominent features, including the subduction zones, cratonic areas, major sedimentary basins and mid-Cretaceous extensional regions. This study presents the first radially anisotropic model across Alaska and surroundings. In the third part of the thesis, I present a hypothesis test to verify whether a simple two-layer azimuthally anisotropic model could fit azimuthal variation in Rayleigh wave phase speed measurements. The hypothesis test confirms our understanding that the crustal azimuthal anisotropy is dominantly produced by deformationally-aligned cracks and fractures in the upper crust undergoing brittle deformation. It also infers the existence of vertically coherent deformation in the uppermost mantle. This is the first study that infers apparent shear wave azimuthal anisotropy beneath Alaska using surface waves from ambient noise and earthquakes.</p

Proteomic Analysis Suggests a Role for HtrA Serine Peptidase 1 in Immune Regulation and Thereby in Age-Related Macular Degeneration

Purpose. Single-Nucleotide Polymorphisms on chromosome 10 at the region 10q26 that harbors the three genes, PLEKHA1, ARMS2 and HtrA1, show strong association with the pathogenesis of age-related macular degeneration (AMD). In the last decade, evidence was mounted that mutations in the HtrA1 gene are a major causative factor of this disorder in Caucasian populations. The current study was undertaken in order to enhance the understanding the role of this HtrA1 in the pathogenesis of AMD. Methods. A HtrA1 gene trap mouse model was employed to compare the differences in protein expression between the gene trap mouse and a wild type mouse. ARPE19 and HeLa cells were transfected with a plasmid coding for triple-tagged, proteolytically inactive HtrA1. Next, a Co-IP assay was used to isolate HtrA1 interacting proteins. Selected candidates were validated with Western blot. Potential substrates of HtrA1 were tested by an in vitro digestion assay. Results. Our study indicated that HtrA1 as a secreted protein binds to various complement components, e.g. CFP, CFD, CFI, C1r, C1s, C2, C3 and C5 in the classical pathway, as well as to components of the lectin-mediated pathway and, in particular, to components of the alternative pathway. Several of these components have been implicated in the pathological process of age-related macular degeneration. Notably, a regulatory component of the innate immune activity, Ubiquitin-like protein ISG15 directly interacts with HtrA1 in our Co-IP. Furthermore, our in vitro digestion assay showed that Ubiquitin-like protein ISG15 is a substrate of HtrA1 protease. Conclusion. The aberrant activation of the complement system by HtrA1 found in our assays underlies the importance of the immune system in the pathogenesis of AMD. Our results suggest that HtrA1 may exert its biological function through the regulation of the immune system.ZIEL: Einzelnukleotid-Polymorphismen (englisch: Single-Nucleotide Polymorphisms, SNP) in dem chromosomalen Bereich 10q26, der die drei Gene PLEKHA1, ARMS2 und HtrA1 enthält, zeigen eine starke Assoziation mit der Pathogenese der Altersbedingten Makuladegeneration (AMD). In den letzten zehn Jahren haben sich zahlreiche Anzeichen dafür gehäuft, dass eine Hauptursache der Erkrankung in einer Mutation des HtrA1 Gens liegen könnte. Mit dieser Studie sollte daher die pathologische Rolle des Gens bzw. Proteins weiter aufgeklärt werden. METHODEN: Ein HtrA1 "gene trap" Mausmodell wurde verwendet, um die Proteinexpression zwischen der gene trap Maus und der Wildtyp Maus zu vergleichen. Des Weiteren wurden ARPE19 Zellen und HeLa Zellen mit einem HtrA1-Plasmid transfiziert, das einen dreifach Tag trägt und für proteolytisch inaktives HtrA1 kodiert. Mittels Co-Immunopräzipitation wurden dann die Proteine präzipitiert, die mit HtrA1 interagieren. Interessante Kandidaten wurden mit Western Blot überprüft. Potentielle HtrA1 Substrats, wurden mittels in vitro Verdau getestet. ERGEBNISSE: Die Ergebnisse dieser Studie zeigen, dass HtrA1 als ein sekretiertes Protein an verschiedene Komponenten des Komplementsystems binden kann, und zwar an die Komponenten CFP, CFD, CFI, C1r, C1s, C2, C3 und C5 aus dem klassischen Weg, sowie an Komponenten des Lektin-Weges und besonders an Komponenten des alternativen Weges. Einige dieser Proteine stehen im Zusammenhang mit der Pathogenese der Altersbedingten Makuladegeneration. Insbesondere konnten wir zeigen, dass das Ubiquitin-like protein ISG15 bei Co-Immunopräzipitation direkt mit HtrA1 interagiert. Bei einem in vitro Verdau war Ubiquitin-like protein ISG15 auch ein Substrat für HtrA1. AUSWERUNG: Die Aktivierung des Komplementsystems durch HtrA1, die wir unseren Assays gefunden haben, unterstützt die Vermutung, dass das Immunsystem eine entscheidende Rolle bei der Pathogenese von AMD spielt. Die Ergebnisse dieser Arbeit lassen vermuten, dass HtrA1 die Aktivität des Immunsystems reguliert

3DCFS : Fast and robust joint 3D semantic-instance segmentation via coupled feature selection

We propose a novel fast and robust 3D point clouds segmentation framework via coupled feature selection, named 3DCFS, that jointly performs semantic and instance segmentation. Inspired by the human scene perception process, we design a novel coupled feature selection module, named CFSM, that adaptively selects and fuses the reciprocal semantic and instance features from two tasks in a coupled manner. To further boost the performance of the instance segmentation task in our 3DCFS, we investigate a loss function that helps the model learn to balance the magnitudes of the output embedding dimensions during training, which makes calculating the Euclidean distance more reliable and enhances the generalizability of the model. Extensive experiments demonstrate that our 3DCFS outperforms state-of-the-art methods on benchmark datasets in terms of accuracy, speed and computational cost

Genome-wide characterization and expression of two-component system genes in cytokinin-regulated gall formation in Zizania latifolia

The thickening of Zizania latifolia shoots, referred to as gall formation, depends on infection with the fungal endophyte Ustilago esculenta. The swollen and juicy shoots are a popular vegetable in Asia. A key role for cytokinin action in this process was postulated. Here, trans-zeatin stimulated swelling in fungi-infected Z. latifolia. A two-component system (TCS) linked cytokinin binding to receptors with transcriptional regulation in the nucleus and played important roles in diverse biological processes. We characterized 69 TCS genes encoding for 25 histidine kinase/histidine-kinase-like (HK(L)) (21 HKs and 4 HKLs), 8 histidine phosphotransfer proteins (HP) (5 authentic and 3 pseudo), and 36 response regulators (RR; 14 type A, 14 type B, 2 type C, and 6 pseudo) in the genome of Z. latifolia. These TCS genes have a close phylogenetic relationship with their rice counterparts. Nineteen duplicated TCS gene pairs were found and the ratio of nonsynonymous to synonymous mutations indicated that a strong purifying selection acted on these duplicated genes, leading to few mutations during evolution. Finally, ZlCHK1, ZlRRA5, ZIRRA9, ZlRRA10, ZlPRR1, and ZlPHYA expression was associated with gall formation. Among them, ARR5, ARR9, and ZlPHYA are quickly induced by trans-zeatin, suggesting a role for cytokinin signaling in shoot swelling of Z. latifolia. Keywords: two-component system; Z. latifolia; shoot swelling; cytokinin signal

Analytic initial relative orbit solution for angles-only space rendezvous using hybrid dynamics method

A closed-form solution to the angles-only initial relative orbit determination (IROD) problem for space rendezvous with non-cooperated target is developed, where a method of hybrid dynamics with the concept of virtual formation is introduced to analytically solve the problem. Emphasis is placed on developing the solution based on hybrid dynamics (i.e., Clohessy-Wiltshire equations and two-body dynamics), obtaining formation geometries that produce relative orbit state observability, and deriving the approximate analytic error covariance for the IROD solution. A standard Monte Carlo simulation system based on two-body dynamics is used to verify the feasibility and evaluate the performance proposed algorithms. The sensitivity of the solution accuracy to the formation geometry, observation numbers is presented and discussed