435,744 research outputs found
Flow over cube arrays of different packing densities
No full textMeasurements by 120° x-wire anemometry over uniform urban-type surfaces of two different area densities were performed in a wind tunnel, together with direct measurements of the surface drag. The aerodynamic characteristics of each surface were determined and compared, the influence of area density and array geometry on these parameters was examined. Various approaches were discussed for the determination of the roughness length (z0) for a given surface. The surface shear stress (determined from form drag measurements by pressure tapping a roughness element or from the total surface drag determined by a floating drag balance) and the shear stress (determined from spatially averaged vertical profiles of Reynolds shear stress) were compared. The surface shear stress was found to be about 25% greater than the measured Reynolds shear stress in the inertial sub-layer over the surfaces. There was, however, no constant stress region and extrapolation of the shear stress profiles in the inertial sub-layer to the zero-plane displacement provided a much better estimate of the surface shear stress. The results did not support the argument put forward in the literature that the zero-plane displacement could be reliably predicted from the height of the centre of drag force. Finally, the accuracy of existing geometrical methods of determining the aerodynamic properties of rough surfaces was shown to be limited by the use of inappropriate wind tunnel data in their formulation
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
The Oxidation of N,N'-Disubstituted O-Phenylenediamine in Presence of Metal Ions and the Crystal Structure of N,N'-Dimethylbenzimidazolium Perchlorate, Pyridinebis(O-Benzo-Semi-Quinonediimine)Cobalt(III) Chloride and Bis(Phridine)-(N,N'-Bis
No full text
ISGG: Cooperative Mission in the AI Era
No full textAt the 21st International Conference on Geometry and Graphics (ICGG2024, August, 2024), an international panel was organized with the In- stitutional Members and Associated National Organizations of ISGG to discuss cooperative mission in the AI era and its relation to the International Society for Geometry and Graphics. This is a summary of the discussion with the panel members Luigi Cocchiarella (Italy), Liang-Yee Cheng (Brazil), Michal Zamboj (Czech Republic), Hans-Peter Schro ̈cker (Austria), Hongming Cai (China), Eva Wohlleben (Germany), Stefano Bertocci (Italy), and Hirotaka Suzuki (Japan)
Search for new hadronic decays of h c and observation of h c → p p ¯ η
No full textAbstract A search for the hadronic decays of the h c meson to the final states p p ¯ π + π − π 0, p p ¯ η , and p p ¯ π 0 via the process ψ(3686) → π 0 h c is performed using (4.48 ± 0.03) × 108 ψ(3686) events collected with the BESIII detector. The decay channel h c → p p ¯ η is observed for the first time with a significance greater than 5σ and a branching fraction of (6.41 ± 1.74 ± 0.53 ± 1.00) × 10 −4, where the uncertainties are statistical, systematic, and that from the branching fraction of ψ(3686) → π 0 h c . Strong evidence for the decay h c → p p ¯ π + π − π 0 is found with a significance of 4.9σ and a branching fraction of (3.84 ± 0.83 ± 0.69 ± 0.58) × 10 −3. The significances include systematic uncertainties. No clear signal of the decay h c → p p ¯ π 0 is found, and an upper limit of 6.59 × 10 −4 on its branching fraction is set at the 90% confidence level
Validity of the Novel Taiwan Lymphoscintigraphy Staging and Correlation of Cheng Lymphedema Grading for Unilateral Extremity Lymphedema
No full textOBJECTIVE: The aim was to validate the new Taiwan Lymphoscintigraphy Staging, correlate it with Cheng Lymphedema Grading (CLG) and evaluate the treatment outcomes of unilateral extremity lymphedema. BACKGROUND: No consensus has been reached for diagnosis and staging for patients with lymphedema among medical specialties. METHODS: We included 285 patients with unilateral extremity lymphedema using lymphoscintigraphy. Lymphoscintigraphy was correlated to clinical symptoms and signs, and classified into normal lymphatic drainage, partial obstruction, and total obstruction. Inter- and intraobserver reliability of Taiwan Lymphoscintigraphy Staging, correlation between Taiwan Lymphoscintigraphy Staging and clinical findings were conducted. Patients were categorized in "surgical" (n = 154) or "nonsurgical" (n = 131) groups for outcome evaluation. RESULTS: Lymphoscintigraphy found 11 patients (3.9%) with normal lymphatic drainage, 128 (44.9%) with partial obstruction, and 146 (51.2%) with total obstruction. Taiwan Lymphoscintigraphy Staging showed high interobserver agreement [intraclass correlation coefficient: 0.89 (95% confidence interval, 0.82-0.94)], and significantly correlated to computed tomography volumetric difference (r = 0.66, P < 0.001) and CLG [intraclass correlation coefficient: 0.79 (95% confidence interval 0.72-0.84)]. At a mean follow-up of 31.2 ± 2.9 months, significant improvement in the circumferential difference (from 23.9% ± 17.6% to 14.6% ± 11.1%; P = 0.03) with a mean circumferential reduction rate of 40.4% ± 4.5% was found in surgical group. At a mean follow-up of 26.6 ± 8.7 months, the nonsurgical group had increase of mean circumferential difference from 24.0% ± 17.2% to 25.3% ± 19.0% (P = 0.09), with a mean circumferential reduction rate was -1.9% ± 13.0%. CONCLUSIONS: The Taiwan Lymphoscintigraphy Staging is a reliable diagnostic tool, correlated with clinical findings and CLG, aiding in the selection of the appropriate treatment to achieve favorable long-term outcomes in unilateral extremity lymphedema
Journal for Geometry and Graphics
No full textThe singular coincidence in 2022, 25th anniversary of the publication of the first issue of the Journal of Geometry and Graphics (JGG), 30th anniversary of the establishment of the International Society for Geometry and Graphics (ISGG), and 80th birthday of Hellmuth Stachel, Professor of Geometry at the Technical University of Vienna (now retired), founder and former Editor in Chief of the JGG, and co-founder of ISGG, suggested the idea of this special issue.
The Editorial Board, formed by the current Editor in Chief who launched the proposal, the President, the Vice-Presidents, and the Treasurer of ISGG, decided to publish the issue as part of the JGG series, in order to reach the audience of readers familiar with the journal, and with the person to whom this issue is dedicated.
The volume includes two editorial sections, “Personal Memories” and “Scientific Contri butions”, in the aim of reflecting the wide spectrum of competences and interests of Hellmuth Stachel, deepened and shared in a life actively spent between research and education, without missing some personal items and anecdotes.
“Personal Memories” consist of short contributions written by people being, or having been, closely connected with Hellmuth Stachel over more than three decades, who share their personal records about his role in science, education, and community services.
“Scientific Contributions” refer to the world wide scientific impact of Hellmuth Stachel, and consist of a number of papers on topics related to Geometry and Graphics, written by authors of various backgrounds and generations, invited from the three ISGG world regions (Asia/Australia/Oceania, Europe/Near East/Africa, North America/South America).
May this special issue celebrating such an exemplary academic profile, inspire all the readers, as well as the whole JGG and ISGG communities, and, why not, initiate a new editorial line inside the JGG series.
On behalf of JGG and ISGG, we warmly address to Professor Hellmuth Stachel our birthday wishes, and cordial greetings to his family and his wife Mrs. Henrike.
The Guest Editorial Board of JGG 26/1
Liang-Yee Cheng, Luigi Cocchiarella, Hans-Peter Schr ̈ocker, Kumiko Shiin
Full Waveform Inversion of P Waves for V[subscript s] and Q[subscript p]
No full textWe present an indirect method of determining shear wave velocities from full waveform
acoustic logs based on the inversion of the spectral ratio of the P-wave trains at two
source-receiver separations. This method simultaneously inverts for the formation shear
wave velocity and compressional wave attenuation. The P-wave response is calculated
by means of branch-cut integration. This method is useful in "soft" formations where
the shear wave velocity is lower than the acoustic velocity of the borehole fluid and
thus there are no refracted shear wave or pseudo-Rayleigh wave arrivals. The method
is shown to give good estimates of formation shear wave velocity in both synthetic and
field data. The inversion algorithm is sensitive to local minima; care must be taken to
avoid them.Massachusetts Institute of Technology. Full Waveform Acoustic Logging ConsortiumNational Science Foundation (U.S.) (Grant OCE84-08761
- …
