9,253 research outputs found
A discrete-time Markov modulated queuing system with batched arrivals
This paper examines a discrete-time queuing system with applications to
telecommunications traffic. The arrival process is a particular Markov
modulated process which belongs to the class of discrete batched Markovian
arrival processes. The server process is a single server deterministic queue. A
closed form exact solution is given for the expected queue length and delay. A
simple system of equations is given for the probability of the queue exceeding
a given length.Comment: to appear Performance Evaluatio
Dynamic response of continuous beams with discrete viscoelastic supports under sinusoidal loading
Analysis of vibrations of continuous beams with discrete viscoelastic supports has been established through theoretical modeling and a finite element analysis. The theoretical model is based on the Euler-Bernoulli theory, and the Ritz approach was employed to obtain numerical results from which the attenuation of the beam's vibration was obtained. In parallel, a finite element analysis was carried out in ABAQUS using 3D beam elements. It is shown that the results of theoretical calculation agree well with those of the finite element analysis. Both models were applied to explore geometric and design variations, and then to a full model of a bridge expansion unit as an application example. The vibration of the beams in the design, the influence of the stiffness and the viscous damping coefficient of the supports were discussed, demonstrating the models' usefulness in helping with design optimization. © 2014 Elsevier Ltd
Effect of implant placement depth on the peri-implant bone defect configurations in ligature-induced peri-implantitis : an experimental study in dogs
The subcrestal placement of implant platform has been considered a key factor in the preservation of crestal bone, but the influence of implant placement depth on bone remodeling combined with peri-implantitis is not fully understood. The aim of this study was to assess the effect of the crestal or subcrestal placement of implants on peri-implant bone defects of ligature-induced peri-implantitis in dogs. Eight weeks after tooth extraction in six beagle dogs, two different types of implants (A: OsseoSpeed?, Astra, Mölndal, Sweden; B: Integra-CP?, Bicon, Boston, USA) were placed at either crestal or subcrestal (-1.5 mm) positions on one side of the mandible. Ligature-induced peri-implantitis was initiated four weeks after the installation of the healing abutment connections. After 12 weeks, tissue biopsies were processed for histological analyses. Supra-alveolar bone loss combined with a shallow infrabony defect was observed in crestal level implants while deep and wide infrabony defects were present in subcrestal level groups. Subcrestal groups showed significantly greater ridge loss, depths and widths of infrabony defects when compared to crestal groups (P<0.001). Within the limitations of the animal study, it can be stated that the implants at subcrestal position displayed greater infra-osseous defect than implants at crestal position under an experimental ligature-induced peri-implantitis
LSMR: An iterative algorithm for sparse least-squares problems
An iterative method LSMR is presented for solving linear systems and
least-squares problem \min \norm{Ax-b}_2, with being sparse or a fast
linear operator. LSMR is based on the Golub-Kahan bidiagonalization process. It
is analytically equivalent to the MINRES method applied to the normal equation
A\T Ax = A\T b, so that the quantities \norm{A\T r_k} are monotonically
decreasing (where is the residual for the current iterate
). In practice we observe that \norm{r_k} also decreases monotonically.
Compared to LSQR, for which only \norm{r_k} is monotonic, it is safer to
terminate LSMR early. Improvements for the new iterative method in the presence
of extra available memory are also explored.Comment: 21 page
2-(1H-Pyrazol-3-yl)pyridinium chloride monohydrate
The title organic salt, C8H8N3
+·Cl−·H2O, exhibits a rich hydrogen-bonding network involving all constituent species. The water molecules are engaged in strong O—H⋯Cl interactions with the chloride anions, two neighboring protonated 2-(1H-pyrazol-3-yl)pyridinium species interact via N—H⋯N bonds with two pyrazole rings. Further, a short and highly directional C—H⋯O interaction is observed connecting the pyridinium ring to the water molecule of crystallization. Weak C—H⋯Cl and N—H⋯Cl interactions contribute to the stabilization of the crystal structure
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