نتایج جستجو برای: surface roughness ra

تعداد نتایج: 672209  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی 1392

flow in natural river bends is a complex and turbulent phenomenon which affects the scour and sedimentations and causes an irregular bed topography on the bed. for the reason, the flow hydralics and the parameters which affect the flow to be studied and understand. in this study the effect of bed and wall roughness using the software fluent discussed in a sharp 90-degree flume bend with 40.3cm ...

Journal: :The journal of contemporary dental practice 2013
Khalid H Al-Samadani

OBJECTIVE To study the effect of three energy drinks on the surface roughness of nanoflled composite resins after different periods of aging time. MATERIALS AND METHODS Composite resin disks, 6 mm diameter, 3 mm thickness were prepared from Filtec Z350 XT, Tetric EvoCeram and Filtec Z250 XT. Specimens fr/8om each material were tested after aging with Red Bull, Bison and Power Horse energy dri...

2007
Lei Li Stuart A. Collins Allen Y. Yi

Although ultraprecision diamond turned optics can have surface roughness down to tens of nanometers or even lower, they may still contain defects due to machining process variations. Diamond turned surfaces have been carefully studied before [3-12]. The previous research however was mainly focused on the causes of the surface texture and one of the main goals of these studies was to improve the...

2016

Introduction Surface roughness of dental restorative materi­ als is most often established with the Ra value obtained using profilometry or by assessing surface topography with the scanning electron microscope (SEM). Both methods should vali­ date each other in confirming surface rough­ ness. Aims and objectives The purpose of this study was to compare sur­ face roughness values obtained with a...

2016
Seyda Ersahan Fidan Alakus Sabuncuoglu

PURPOSE To compare the effects of different methods of surface treatment on enamel roughness. MATERIALS AND METHODS Ninety human maxillary first premolars were randomly divided into three groups (n=30) according to type of enamel surface treatment: I, acid etching; II, Er:YAG laser; III, Nd:YAG laser. The surface roughness of enamel was measured with a noncontact optical profilometer. For eac...

2016
Thammarat Somthong Qing-Ping Yang

This paper presents a technique for measuring surface roughness (Ra), using photometric stereo method. The method utilizes three or more images of the measured surface from the same view point, taken sequentially under different illumination conditions. The scenes captured by the camera were reconstructed by the least square method to obtain surface normal from surface topography. Three-dimensi...

2007
C. Walter T. Antretter C. Mitterer

The effect of the surface roughness on nanoindentation results was investigated instancing a series of CrN thin films deposited by unbalanced magnetron sputtering. The arithmetic roughness (Ra) of the films ranged between 2 and 10 nm and was measured by atomic force microscopy. The measured surface topography was incorporated into a finite element model, which allowed simulating the indentation...

2016
Thammarat Somthong Qingping Yang

This paper presents a technique for measuring surface roughness (Ra), using photometric stereo method. The method utilizes three or more images of the measured surface from the same viewpoint, taken sequentially under different illumination conditions. The scenes captured by the camera were reconstructed by the least square method to obtain surface normal from surface topography. Three-dimensio...

2011
P. K. Bardhan R. Behera S. Patra G. Sutradhar

The surface roughness value (Ra) of sintered iron P/M components at different cutting speed has been investigated. Surface finish may also be critical for component assembly or system performance. Dimensional fit and mating surface interaction may require certain surface finish requirements to meet performance specifications. Experimental results of surface roughness (Ra) of P/M components at d...

2009
Kristine Guará Brusaca Almeida Scheibe Karoline Guará Brusaca Almeida Igor Studart Medeiros José Ferreira Costa Cláudia Maria Coêlho Alves

The use of composite resins in dentistry is well accepted for restoring anterior and posterior teeth. Many polishing protocols have been evaluated for their effect on the surface roughness of restorative materials. This study compared the effect of different polishing systems on the surface roughness of microhybrid composites. Thirty-six specimens were prepared for each composite $#91;Charisma ...

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