199 research outputs found
Intracavity optogalvanic spectroscopy applied to radiocarbon detection
No full textRadiocarbon is extremely useful for archeological dating as well as for clinical, laboratory and atmospheric tracer applications. In this thesis, we report a new physical description of the ICOGS system process of radiocarbon optogalvanic signal extraction and analysis. To be specific, we first describe the fundamental theory of the Optogalvanic effect. Based on a set of 4-energy level rate equations for N2 buffer gas and a set of 2-energy level for CO2 sample gas, we simulate the N2 and CO2 ICOGS OG signals. Moreover, according to the phase difference from our simulation and experiment observation, we propose three methods (1.Vector Phase and Amplitude fitting, 2.Differential Method and 3.Vector Decomposition Method) to separate CO2 OG signal from N2 OG signal. Experimental results demonstrate our quantitative radiocarbon detection near 10 zeptomole14C levels in 10 µg samples.M.S.Includes bibliographical referencesby Junming Li
Magnetoelectric study in Terfenol-D/Tb₂(MoO₄)₃ bilayer composite
No full textAuthor name used in this publication: Junming LiuAuthor name used in this publication: Jiyang Wang2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedVoR allowe
Acculturation and quality of life of Chinese Mainland students in Northern B.C.
No full textThis study used a quantitative method to explore the acculturation process and quality of life of Chinese Mainland students in Prince George in Northern B.C. It mainly focuses on the effect of residence time on acculturation and quality of life, as well as gender differences in these two aspects among the study subjects. U-curve of adjustment theory (UCT) served as the conceptual framework. Chinese Mainland students who are currently studying in Northern B.C. were recruited to complete a 40-question survey (N=95). Results indicated that participants showed a semi-U' shape cultural adaptation process. However, no significant difference was found between the two genders on acculturation. The findings also demonstrated that the students' quality of life correlates to their acculturation level. Despite no difference in acculturation between males and females, they do significantly differ on quality of life in terms of psychological health and social connectivity. --Leaf iii.The original print copy of this thesis may be available here: http://wizard.unbc.ca/record=b186107
Four-dimensional complete gradient shrinking Ricci solitons with half positive isotropic curvature
No full textIn this paper, we investigate the geometry of 4-dimensional complete gradient
shrinking Ricci solitons with half positive isotropic curvature (half PIC) or
half nonnegative isotropic curvature. Our first main result is a certain form
of curvature estimates for such Ricci shrinkers, including a quadratic
curvature lower bound estimate for noncompact ones with half PIC. As a
consequence, we obtain a new and more direct proof of the classification
result, first observed by Li-Ni-Wang [35], for gradient shrinking
K\"ahler-Ricci solitons of complex dimension two with nonnegative isotropic
curvature. Moreover, based on a strong maximum principle argument, we classify
4-dimensional complete gradient shrinking Ricci solitons with half nonnegative
isotropic curvature (except the half PIC case). Finally, we treat the half PIC
case under an additional assumption on the Ricci tensor.Comment: 22 pages; added the new Corollary 1.2 and the proofs of Lemma 2.1 and
formula (2.14
Four-dimensional gradient Ricci solitons with (half) nonnegative isotropic curvature
No full textThis is a sequel to our paper [24], in which we investigated the geometry of
4-dimensional gradient shrinking Ricci solitons with half positive
(nonnegative) isotropic curvature. In this paper, we mainly focus on
4-dimensional gradient steady Ricci solitons with nonnegative isotropic
curvature (WPIC) or half nonnegative isotropic curvature (half WPIC). In
particular, for D complete {\it ancient solutions} with WPIC, we are able to
prove the nonnegativity of the Ricci curvature and bound the
curvature tensor by . For 4D gradient steady solitons with
WPIC, we obtain a classification result. We also give a partial classification
of 4D gradient steady Ricci solitons with half WPIC. Moreover, we obtain a
preliminary classification result for 4D complete gradient {\it expanding Ricci
solitons} with WPIC. Finally, motivated by the recent work [60], we improve our
earlier results in [24] on 4D gradient {\it shrinking Ricci solitons} with half
PIC or half WPIC, and also provide a characterization of complete gradient
K\"ahler-Ricci shrinkers in complex dimension two among 4-dimensional gradient
Ricci shrinkers.Comment: 21 pages; v.2: added Remark 1.3 & Remark 6.
GlassGaussian: Extending 3D Gaussian Splatting for Realistic Imperfections and Glass Materials
No full text3D scene reconstruction methods have made significant advancements in handling reflections. However, these methods are primarily effective on ideal mirror surfaces, which limits their applicability in real-world scenarios where imperfections or materials such as glass. The inability of current state-of-the-art (SOTA) methods to accurately model these complex reflective surfaces often results in artifacts and a significant drop in rendering quality. This paper introduces a novel extension to 3D Gaussian Splatting techniques by modifying the image fusion equation and incorporating a single-channel Spherical Harmonics representation to measure the reflectance of each Gaussian kernel from different directions. For glass scene renderings, our method shows an approximate 1dB PSNR improvement compared to current SOTA techniques. Comprehensive experiments demonstrate the effectiveness of our approach in various challenging scenarios
Large-Scale Indoor Visual–Geometric Multimodal Dataset and Benchmark for Novel View Synthesis
No full textThe accurate reconstruction of indoor environments is crucial for applications in augmented reality, virtual reality, and robotics. However, existing indoor datasets are often limited in scale, lack ground truth point clouds, and provide insufficient viewpoints, which impedes the development of robust novel view synthesis (NVS) techniques. To address these limitations, we introduce a new large-scale indoor dataset that features diverse and challenging scenes, including basements and long corridors. This dataset offers panoramic image sequences for comprehensive coverage, high-resolution point clouds, meshes, and textures as ground truth, and a novel benchmark specifically designed to evaluate NVS algorithms in complex indoor environments. Our dataset and benchmark aim to advance indoor scene reconstruction and facilitate the creation of more effective NVS solutions for real-world applications
Complete gradient expanding Ricci solitons with finite asymptotic scalar curvature ratio
No full textLet , , be a complete gradient expanding Ricci soliton
with nonnegative Ricci curvature . In this paper, we show that if the
asymptotic scalar curvature ratio of is finite (i.e., ), then the Riemann curvature tensor must
have at least sub-quadratic decay, namely, for any .Comment: 20 pages. Lemma 3.1 statement simplified; the proof of Lemma 3.2 &
Lemma 3.3 streamlined. arXiv admin note: text overlap with arXiv:2111.0984
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