نتایج جستجو برای: bit nozzle
تعداد نتایج: 61061 فیلتر نتایج به سال:
Heap spraying is a security attack that increases the exploitability of memory corruption errors in type-unsafe applications. In a heap-spraying attack, an attacker coerces an application to allocate many objects containing malicious code in the heap, increasing the success rate of an exploit that jumps to a location within the heap. Because heap layout randomization necessitates new forms of a...
A model of a linear aerospike rocket nozzle that consists of coupled aerodynamic and structural analyses has been developed. A nonlinear computational fluid dynamics code is used to calculate the aerodynamic thrust, and a three-dimensional finite-element model is used to determine the structural response and weight. The model will be used to demonstrate multidisciplinary design optimization (MD...
This paper describes results of a factorial experiment on coal cutting at a traverse speed of 5 meters/min, with water jets at pressures between 500 and 2,000 atmospheres and nozzle diameters in the range from 0.5 to 1 mm. These results fill a gap in the existing results on coal cutting with water jets and form the basis for the design of a coal cutting machine. The interrelationship between pr...
The main task of drilling the formation by the bit is done via scraping, crushing and grinding. Discharging the fluid from the bit nozzles is done with high pressure which assists to break the rocks. Different parameters affect the bit selection and design for each drilling formation, but the most important one is drillability that depends on hardness of the formation. In this paper, the design...
A high-resolution stereoscopic particle image velocimetry (PIV) system was used to conduct three-dimensional measurement of an air jet exhausted from a lobed nozzle. The characteristics of the mixing process in the lobed jet ow are revealed clearly and quantitatively from the stereoscopic PIV measurement results. The instantaneous velocity and streamwise vorticity distributions revealed that ...
Background: The aim was to unravel how the air-polishing behaves on a titanium surface by evaluating the size and the shape of the cleaned area, influence of the different device settings, and pocket depths and cleaning movements. Methods: 48 titanium SLA surface film-coated discs were treated with an air abrasive system using a subgingival plastic nozzle. Two subgingival models were employed: ...
We designed a specially designed coaxial spinneret in this study. The inner stainless-steel needle was connected to the inner plastic syringe just like the traditional one. The outer stainless-steel needle was replaced by a plastic nozzle, and connected to the outer plastic syringe. The tip of the inner stainless-steel needle was shortened 2 cm from the tip of the outer plastic nozzle. This str...
Article history: Received: 09.06.2015. Received in revised form: 01.10.2015. Accepted: 08.10.2015. Liquid nitrogen is expected to be used as a jet medium in petroleum engineering because of its cryogenic and non-polluting characteristics. To identify the velocity distribution characteristics of liquid nitrogen jet, a computational fluid dynamics model was built by coupling the equations for nit...
Experiments measuring the single-cycle impulse from detonation tubes with nozzles were conducted by hanging the tubes in a ballistic pendulum arrangement within a large tank. The detonation-tube nozzle and surrounding tank were initiallyfilledwith air between 1.4 and 100kPa in pressure simulating high-altitude conditions.A stoichiometric ethylene–oxygen mixture at an initial pressure of 80 kPa ...
Background and Aims: Optimization drilling parameters in order to temperature decrease during creation of hole in the bone is an interested issue. The aim of this study was to achieve optimum values of drilling parameters based on the creation of minimum temperature during jawbone drilling. Materials and Methods: In this study two models of mandible and maxilla was created and teeth 2, 5...
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