376 research outputs found
ALEA III: The Kucyna International Composition Competition Finalists Concert, September 24, 1988
Get PDFThis is the concert program of the ALEA III: The Kucyna International Composition Competition Finalists Concert performance on Saturday, September 24, 1988 at 7:00 p.m., at the Boston University Concert Hall, 855 Commonwealth Avenue, Boston, Massachusetts. Works performed were String Quartet by Eleanor Cory, Erotic Trilogy by Dimitrios Minakkis, Sérénade Magique, Evocation et Apparitions by Kenneth Olson, Des Lebewohl by Sydney Hodkinson, Painting by Konstantin Bokas, Serenade and Tarantella by Hans Vogt, Dialoques Entre Mètropes by Pietro Borradori, Array! Surrection! by James W. Bennet, III, Twisted Figues by William Susman, and Sonchrivated by Chengyong Wang. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund
A globally distributed dataset of coseismic landslide mapping via multi-source high-resolution remote sensing images
Get PDFRapid and accurate mapping of landslides triggered by extreme events is essential for effective emergency response, hazard mitigation, and disaster management. However, the development of generalized machine learning models for landslide detection has been hindered by the absence of a high-resolution, globally distributed, event-based dataset. To address this gap, we introduce the Globally Distributed Coseismic Landslide Dataset (GDCLD), a comprehensive dataset that integrates multi-source remote sensing images, including PlanetScope, Gaofen-6, Map World, and uncrewed aerial vehicle (UAV) data, with varying geographical and geological background for nine events across the globe. The GDCLD data are freely available at https://doi.org/10.5281/zenodo.13612636 (Fang et al., 2024). In this study, we evaluated the effectiveness of GDCLD by comparing the mapping performance of seven state-of-the-art semantic segmentation algorithms. These models were further tested by three different types of remote sensing images in four independent regions, with the GDCLD-SegFormer model achieving the best performance. Additionally, we extended the evaluation to a rainfall-induced landslide dataset, where the models demonstrated excellent performance as well, highlighting the dataset's applicability to landslide segmentation triggered by other factors. Our results confirm the superiority of GDCLD in remote sensing landslide detection modeling, offering a comprehensive database for rapid landslide assessment following future unexpected events worldwide.</p
Effect of Micro Abrasive Slurry Jet Polishing on Properties of Coated Cemented Carbide Tools
No full textAbstract Owing to the popularization of coating technology, physical Vapor Deposition (PVD) coated tools have become indispensable in the cutting process. Additionally, the post-treatment of coated tools applied to industrial production can effectively enhance the surface quality of coating. To improve the processing performance of coated tools, micro abrasive slurry jet (MASJ) polishing technology is first applied to the post-treatment of coated tools. Subsequently, the effects of process parameters on the surface quality and cutting thickness of coating are investigated via single-factor experiments. In the experiment, the best surface roughness is obtained by setting the working pressure to 0.4 MPa, particle size to 3 μm, incidence angle to 30°, and abrasive mass concentration to 100 g/L. Based on the results of the single-factor experiments, combination experiments are designed, and three types of coated tools with different surface qualities and coating thicknesses are obtained. The MASJ process for the post-treatment of coated tools is investigated based on a tool wear experiment and the effects of cutting parameters on the cutting force and workpiece surface quality of three types of cutting tools. The result indicates that MASJ machining can effectively improve the machining performance of coated tools
Développement de l'outil de coupe revêtu Hf-B et Hf-B-N pour l'usinage à grande vitesse d'alliages de titane
No full textLes alliages de titane ont été largement utilisés dans les domaines de l'aéronautique, de l'automobile, et al. en raison de ses excellentes propriétés physiques et chimiques. Cependant, ce sont aussi des matériaux difficiles à couper en raison de leur résistance élevée, de leur faible conductivité thermique, de leur grande réactivité chimique, etc. L'usure rapide des outils lors de l'usinage à grande vitesse des alliages de titane entraîne une faible efficacité de production et un coût élevé. L’objectif de cette thèse est de développer le revêtement d’outil en carbure cémenté spécifique à l’usinage à grande vitesse des alliages de titane. Les résultats de la recherche expérimentale ont montré que la résistance de l’adhésion au titane était la propriété nécessaire du carbure cémenté revêtu lors de l’usinage à grande vitesse d’alliages de titane. Les revêtements des systèmes Hf-B et Hf-B-N ont été mis en avant en tenant compte des propriétés requises. La prédiction de structure, les propriétés élastiques / plastiques, la résistance au titane de ces deux systèmes ont été calculées et simulées par le premier calcul de principe et la dynamique des molécules ab initio. Un revêtement avec les propriétés et les structures requises a été déposé sur les carbures cémentés grâce à l’optimisation des processus de pulvérisation magnétron et des technologies de caractérisation associées. De plus, les performances de coupe de l'outil revêtu lors de l'usinage à grande vitesse d'alliages de titane ont été évaluées et les résultats ont montré que les nouveaux outils revêtus développaient d'excellentes performances de coupe avec une durée de vie prolongée, une force de coupe réduite et une qualité de surface améliorée.Titanium alloys have been widely used in the fields of aeronautics, automotive, et al. due to its excellent combining physical and chemical properties. However, they are also difficult-to-cut materials because of high strength, low thermal conductivity, high chemical reactivity, et al. Rapid tool wear during the high speed machining of titanium alloys leads to low production efficiency and high cost. The aim of this thesis is to develop the coating of cemented carbide tool specific for the high speed machining of titanium alloys. The demanding properties of the coated cemented carbide during high-speed machining of titanium alloys under green cooling strategies were revealed by the experimental research. The results shown that adhesion resistance to titanium is the necessary property. Coatings of Hf-B and Hf-B-N system were put forwarded by considering the properties required. Structure prediction, elastic/plastic properties, titanium resistance of these two systems were calculated and simulated by the first principle calculation and ab initio molecule dynamics. Coating with required structures and properties were deposited on the cemented carbides through the optimization of magnetron sputtering processes and related characterization technologies. Moreover, the cutting performance of the coated tool during the high-speed machining of titanium alloys was evaluated, and the results showed that the newly developed coated tools had excellent cutting performance with extended tool life, reduced cutting force and improved surface quality
Interleukin 35 Rescues Regulatory B Cell Function, but the Effect Is Dysregulated in Ulcerative Colitis
No full textRESEARCH ON CUTTING VIBRATION OF HIGH SPEED MILLING HIGH HARDNESS HARDENED STEEL WITH COATED TOOLS
No full textHigh speed milling of high hardness hardened steel has the characteristics of high cutting speed and high machining surface hardness,smooth and efficient milling can ensure quality and accuracy,while the generation of cutting vibrations limits the superiority of hard cutting technology. By designing high speed milling of high hardness（ HRC 48 ～ 68）hardened steel under different technological parameters,the cutting vibration signal was collected by LMS Test 9 A experiment analysis software,and the time and frequency domain analyses were analyzed,the relationships among the cutting vibration,the hardness and cutting technological parameters of the hardened steel were studied. The results showed that when the hardness of hardened steel increased,the friction between the rake face of the coated tool and the hardened steel increased,the friction resistance in the feed direction increased,and the amplitude of the vibration signal increased; the vibration signals generated by Ti Al N and Al Cr N coated tools were smaller than those of Ti Si N and Cr Si N coated tools; the addition of Al element in the coating design has a positive effect on suppressing and reducing cutting vibration of hardened steel; the changes of cutting parameters had different effects on the cutting vibration in the feed direction of the cutting tool; in order to obtain a lower cutting vibration amplitude and higher cutting efficiency,the cutting parameter value should be selected in preference to minimize cutting vibration
One type of duplex appendix: horseshoe appendix
No full textJin Liu,1,* Chengyong Dong,2,* Haibo Wang,2 Deguang Sun,2 Rui Liang,2 Zhenming Gao,2 Liming Wang1,2 1General Surgery, Center for New Material and New Precision Technology of Cancer Therapy, Dalian Medical University, Dalian, Liaoning, China; 2Division of Hepatobiliary and Pancreatic Surgery, Department of General Surgery, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China *These authors contributed equally to this work Abstract: A horseshoe appendix is a subtype of duplex appendix, in which the appendix is shaped like a circle that may lead to an internal hernia and result in intestinal necrosis. This subtype is extremely rare, with only 13 cases reported worldwide to date, and easily triggers a series of medico-legal consequences due to the neglect of another infection base of the appendix. We describe a 22-year-old man who presented with a 3-day history of fever and was diagnosed with pneumonia. After receiving antibiotics for 3 days in the Department of Pneumology, he was found to have a periappendiceal abscess. He underwent appendectomy after 3 days of conservative treatment failure in the Department of General Surgery. During the operation, we found that he had a horseshoe appendix with the two bases forming a circle, each communicating with the cecum. We provide a review of 13 cases presented in the literature, with a discussion of the clinical features, diagnosis, and surgical approach of the horseshoe appendix to make the general surgeon get a clear concept of this type of appendicitis. Keywords: appendix malformation, hernia, intestinal obstruction, embryonic development, appendix neoplas
μ-Average n-Widths on the Wiener Space
No full textAbstractIn this paper we consider the μ-average widths of integral operator Tm on the Wiener space C. Some weakly asymptotically exact estimates for the Gelfand width and other widths are obtained
Comparative Study of Dynamic Stall under Pitch Oscillation and Oscillating Freestream on Wind Turbine Airfoil and Blade
No full textThis study aims to assess the dynamic stall of the wind turbine blade undergoing pitch oscillation (PO) and oscillating freestream (OF), respectively. Firstly, a thin-airfoil theoretical analysis was performed to differentiate between these two dynamic effects. During upstroke, PO results in a positive effective airfoil camber, while OF has an additional negative effective airfoil camber, and yet in contrast during downstroke, PO decreases the effective camber, while OF increases the effective camber. Secondly, the equivalence relation between PO and OF is investigated by numerically solving the unsteady Reynolds-averaged Navier-Stokes equations. The difference between PO and OF mainly exists in the linear part of the aerodynamic loads. Because the difference is great at high reduced frequencies or angle of attack (AOA) amplitudes, PO and OF should be treated separately for dynamic stall from different aerodynamic sources. Thirdly, the Beddoes-Leishman dynamic model coupled with Bak’s rotational stall delay model was used to predict the yawed responses of the blade section. The obtained results show different aerodynamic responses between PO and OF, although consideration of rotational augmentation can greatly improve the accuracy of the lift and drag coefficients. To improve the understanding and coupling modeling of rotational augmentation and dynamic stall, an extended analysis of the coupled effect was performed as well
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