o bjectives: correct determination of working length is an important step for suc- cess of endodontic therapy. conventional radiography has limitations in providing the accurate location of apical foramen. for this reason, electronic apex locators (eals) were developed to shorten the treatment time and decrease the radiation dose. the aim of this study was to evaluate the accuracy of root zx ea...

We study the optimal packing of hard spheres in an infinitely long cylinder, using simulated annealing, and compare our results with the analogous problem of packing disks on the unrolled surface of a cylinder. The densest structures are described and tabulated in detail up to D/d=2.873 (ratio of cylinder and sphere diameters). This extends previous computations into the range of structures whi...

Under conditions of lean fueling or high exhaust gas recirculation, interactions between residual cylinder gas and freshly injected fuel and air produce undesirable combustion instabilities in spark-ignition engines. The resulting dynamics can be described as noisy bifurcations of a nonlinear map and are complicated by cylinder-to-cylinder coupling. We discuss the key dynamic features relevant ...

The present paper describes dynamic modelling, results of simulation and experimental investigation of a hydraulic stepper cylinder, which find application in manipulators and robots. The method of bond graph is used for modelling of the dynamics of the considered cylinder design. First, an initial digital simulation is performed in order to calculate basic dynamic characteristics of the cylind...

background and aims. hypodontia is a common developmental abnormality of dentition. this study aimed to determine tooth width in patients affected with mild hypodontia and compare the results with a control group without tooth agenesis. materials and methods. the orthodontic records of 25 patients with congenital missing of one or two teeth (hypodontia group), and 25 subjects with full dentitio...

Experiments were conducted to obtain the modal damping ratios of two hollow cylinders of different thicknesses of Aluminum. An electro dynamic exciter with slip table is used to excite the hollow cylinders. The hollow cylinder (unit under test) is fastened to the exciter. The exciter is placed in the horizontal direction and connected to the slip table. A control accelerometer is placed at the ...

Exact solution is obtained for electromagnetic field around a conducting cylinder of infinite length and finite radius, with a periodical axial current, when the wave length is much larger than the radius of the cylinder. The solution describes simultaneously the fields in the near zone close to the cylinder, and transition to the wave zone. Proper long-wave oscillations of such cylinder are st...

The purpose of this study was to evaluate the effect of dual bonding technique by comparing microshear bond strength between two different luting methods of resin cement to tooth dentin. Three dentin bonding systems(All-Bond 2, One-Step, Clearfil SE Bond), two temporary cements (Propac, Freegenol) were used in this study. In groups used conventional luting procedure, dentin surfaces were left u...

We numerically solve the nonlinear Poisson–Boltzmann equation for two cylinders confined by two parallel charged plates. The repulsive electrical double layer component of the cylinder pair potential is substantially reduced by confinement between like-charged plates. While the effective cylinder surface charge is increased by the confinement, the effective interaction screening length is reduc...