276 research outputs found
Recommended from our members
Elastodynamic analysis of a propagating finite crack in a micropolar elastic solid
A dynamic propagation of a finite crack of opening
mode in a micropolar elastic solid was investigated.
By using an integral transform method, a pair of twodimensional
singular integral equations governing
stress and couple stress was formulated in terms of the
displacement transverse to the crack, macro- and microrotations,
and microinertia. These integral equations
are solved numerically. Solutions for dynamic stress
intensity and couple stress intensity factors are obtained
by utilizing the values of the strengths of the
square root singularities in the macro-rotation and the
gradient of the micro-rotation at the crack tips. The
motion of the crack tips and the load on the crack surface
are not prescribed in the formulation of the problem.
Therefore, the method of solution is applicable
to nonuniform rates of propagation of a crack under an
arbitrary time-dependent load on the crack surface.
The behavior of the micro-rotation field, and the dynamic
couple stress intensity factor, which are influenced
by microinertia, in addition to the dynamic
stress intensity factor, are examined. The classical
elasticity solution for the corresponding problem follows
as a special case of our solution when the micropolar
moduli are dropped
Methods and performance of a three-dimensional whole-core transport code DeCART
DeCART is a three-dimensional whole-core transport code capable of performing direct core calculations at power generating conditions without involving a priori homogenized few-group constant generation. In this paper, the methods of DeCART, which are characterized by the planar method of characteristics (MOC) solutions, the cell based coarse mesh finite difference (CMFD) formulation, the subgroup method for resonance treatment and subpin level thermal feedback, are presented as a whole. The performance of the code in the aspect of solution accuracy and computing speed is then examined using the applications to the C5G7MOX benchmark and its modified rodded variation problems and also to a three-dimensional core case involving thermal feedback. The examination indicates that accurate direct whole core calculations with subpin level thermal feedback for practical PWR problems are quite possible on affordable LINUX clusters within a time span of a few hours.This work was supported by the International Nuclear Energy Research Initiative (I-NERI) program jointly funded by the Ministry of Science and Technology of Korea and the Department of Energy of the United States
Induction chemotherapy in head and neck squamous cell carcinoma of the paranasal sinus and nasal cavity: A role in organ preservation
Background/Aims: The role of induction chemotherapy (IC) for eyeball preservation has not been established in head and neck squamous cell carcinoma (HNSCC) of the paranasal sinus and nasal cavity (PNSNC). Periorbital involvement frequently leads to eyeball exenteration with a margin of safety. We evaluated the treatment outcomes, including survival and eyeball preservation, of patients who received IC for HNSCC of the PNSNC. Methods: We reviewed 21 patients diagnosed with HNSCC of the PNSNC who were treated with IC. We analyzed response, eyeball preservation rate, and overall survival. Results: Tumors were located in the paranasal sinus (n = 14) or nasal cavity (n = 7). Most patients had stage T4a (n = 10) or T4b (n = 7) disease. More than half of the patients received a chemotherapy regimen of docetaxel, fluorouracil, and cisplatin (n = 11). Thirteen patients (61.9%) achieved a partial response after IC and 15 patients (71.4%) achieved T down-staging. Among 17 patients with stage T4 disease, which confers a high risk of orbital exenteration, 14 (82.4%) achieved preservation of the involved eye. The 3-year overall survival (OS) rate of patients who achieved a partial response to IC was 84.6%. The 3-year OS rate of patients with stable disease or disease progression after IC was 25.0% (p = 0.038). Conclusions: IC could be considered for down-staging patients with advanced T-stage disease. It could also be a reasonable option for eyeball preservation in locally advanced HNSCC of the PNSNC.
The First Very Long Baseline Interferometry Image of 44 GHz Methanol Maser with the KVN and VERA Array (KaVA)
We have carried out the first very long baseline interferometry (VLBI)
imaging of 44 GHz class I methanol maser (7_{0}-6_{1}A^{+}) associated with a
millimeter core MM2 in a massive star-forming region IRAS 18151-1208 with KaVA
(KVN and VERA Array), which is a newly combined array of KVN (Korean VLBI
Network) and VERA (VLBI Exploration of Radio Astrometry). We have succeeded in
imaging compact maser features with a synthesized beam size of 2.7
milliarcseconds x 1.5 milliarcseconds (mas). These features are detected at a
limited number of baselines within the length of shorter than approximately 650
km corresponding to 100 Mlambda in the uv-coverage. The central velocity and
the velocity width of the 44 GHz methanol maser are consistent with those of
the quiescent gas rather than the outflow traced by the SiO thermal line. The
minimum component size among the maser features is ~ 5 mas x 2 mas, which
corresponds to the linear size of ~ 15 AU x 6 AU assuming a distance of 3 kpc.
The brightness temperatures of these features range from ~ 3.5 x 10^{8} to 1.0
x 10^{10} K, which are higher than estimated lower limit from a previous Very
Large Array observation with the highest spatial resolution of ~ 50 mas. The 44
GHz class I methanol maser in IRAS 18151-1208 is found to be associated with
the MM2 core, which is thought to be less evolved than another millimeter core
MM1 associated with the 6.7 GHz class II methanol maser.Comment: 19 pages, 3 figure
Source-Frequency Phase-Referencing Observation of AGNs with KaVA Using Simultaneous Dual-Frequency Receiving
The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving
mode is demonstrated to be promising for mm-VLBI observations. Recently, other
Very long baseline interferometry (VLBI) facilities all over the globe start to
implement compatible optics systems. Simultaneous dual/multi-frequency VLBI
observations at mm wavelengths with international baselines are thus possible.
In this paper, we present the results from the first successful simultaneous
22/43 GHz dual-frequency observation with KaVA(KVN and VERA array), including
images and astrometric results. Our analysis shows that the newly implemented
simultaneous receiving system has brought a significant extension of the
coherence time of the 43 GHz visibility phases along the international
baselines. The astrometric results obtained with KaVA are consistent with those
obtained with the independent analysis of the KVN data. Our results thus
confirm the good performance of the simultaneous receiving systems for the
non-KVN stations. Future simultaneous observations with more global stations
bring even higher sensitivity and micro-arcsecond level astrometric
measurements of the targets.Comment: 8 pages, 6 figures, Published in JKA
- …