25 Ocak 2014 Cumartesi

GLONASS GPS VE KULLANIM ALANLARI

GLONASS Nedir?

Orijinal olarak GPS teknolojisi Amerikan ordusu için üretilmiş bir teknolojir. Fakat bazı hava kazalarının önlenmesi adına sivil kullanıma da açılmış durumdadır. Yeni cep telefonlarımızda sadece GPS uydularının değil Rusların geliştirdiği Glonass uydularının da bilgileri alınabiliyor ve bunlar size özellikle o ekvatora uzaklaştığınızda daha fazla işe yarayacak şekilde sinyal gönderebiliyorlar. Dünyanın her tarafında iki farklı şebekeden gelen sinyallerle birlikte yolumuzu daha iyi şekilde bulabileceğiz. Böylece akıllı telefonlarınızda ve gps cihazlarınızda kolayaca yönünüzü bulubileceksiniz.
  Dünyada 31 adet gps 24 adette glonass uydusu mevcutmuş gps+glonass destekli cihazlar bu 55 uydudan yararlanarak daha hızlı ve net sonuçlar alarak gps bağlantısı yapabilmektedir. Resimde görüldüğü gibi GLONASS uyduları GPS uydularına göre yeryüzüne daha yakın olduğundan sinyal seviyeleri daha yüksektir.Türkiye’de Glonass uyduları görülebilir ve navigasyon için kullanılabilir.

 Glonass teknolojisi birçok akıllı telefon üreticileri tarafından tercih edilmeye başlandı. Başta Samsung, İphone,Sony,LG ve birçok markalar telefonlarında  GLONASS gps kullanmaya başladı.Bunun dışında Mediatek işlemcili cihazlarda GLONASS desteği yoktur.



Normal GPS özelliği olan cihazla GLONASS destekli cihaz arasında karşılaştırmalar yapılmıştır. GLONASS destekli cihazlar 22 uydu bulup daha çabuk bağlantı sağlamıştır. Artık birçok akıllı telefon üreticileri GLONASS destekli telefonlarını pazara çıkarıyor. Yeni bir telefon aldığınızda GLONASS desteğine dikkat edin.Aşağıdaki video da GLONASS desteği olan telefonla diğer sadece AGPS desteği olan karşılaştırmasını ve aradaki farkı görebilirsiniz.



BEARINGS AND COMMON BEARING TYPES

GENERAL  USED BEARING TYPES FOR INDUSTRY

A bearing is a machine element that constrains relative motion between moving parts to only give the desired motion. The design of bearing may be provide for free linear movement of the moving parts or free rotation around a fixed axis or it may prevent motion by controlling the vectors of normal forces that bear on the moving parts .They are mainly used to minimize the friction between moving parts.
SHORT HISTORY OF BEARING

The invention of the rolling bearing, within the sort of wood rollers supporting, or bearing, associate object being affected is of nice antiquity, and may predate the invention of the wheel. The ball bearing was originally described by GALILEO in the 17th century.
01-bearings-sealed ball bearings-high temperature bearings
Bearings played a significant role in technological revolution allowing the new industrial machinery to work with efficiency. There are various types of bearings according to purpose of usages. The most common bearing is plain bearing which uses lubricant between the rubbing surfaces.
Types of bearings:
  • Plain Bearing
  • Journal bearing
  • Sleeve bearing
  • Rolling element Bearing
  • Jewel Bearing
  • Fluid Bearing
  • Magnetic Bearing
  • Flexure Bearing

  • Common motions permitted by bearing are as follows
    • Axial Rotation
    • Linear Motion
    • Spherical Rotation
    • Hinge Motion
    Bearings are designed on the purpose of the following subjects
    • Friction
    • Speeds
    • Loads
    • Purpose
    • Stiffness
    • Life
    Maintenance and Lubrication of a Bearing is very important. The external factors that effect a bearing are electrical signals, temperature,exposure to environment. To prevent bearing from these external factors they should be frequently lubricated and maintained properly.
    Plain Bearing:
    They have rubbing surfaces with lubricants between them .Friction factor depends on the material and construction. Stiffness is good. Life depends on application and also depends on lubrication
    01-plain_bearing-linear_bearing-sleeve_bearing
    Roller Bearing:
    Ball or rollers are used between rotating surfaces. This prevent and minimize the friction. Life is moderate and speed changes according to requirements. These kind of bearings are widely used now a days.
    01-roller bearing-thrust roller bearing-roller ball bearing
    Jewel bearing:
    Jewel bearing has an off centre bearing rolls in seating. Friction of this bearings is very low.  Speed and life are low.
    01-jewel bearings-plastic bearings
    Fluid Bearing:
    In these bearings fluid is forced between two faces and held in by edge seal. Friction is zero at zero speed. Stiffness is very high. Can be used for high speed applications. Life is infinite in some applications.
    01-fluid bearings-fluid circulative bearings-liquid bearings
    Magnetic Bearing:
    The two faces of bearing are kept separate by magnets. Zero friction at zero speed but eddy currents are often induced. Stiffness is low and there is no practical limit for speed and life.
    01-magnetic bearing-magnetic levitation bearings
    fag active magnetic bearing, magnetlager
    Flexure Bearing:
    These bearings are provided with material flexes to give any constrain movement. Friction is very low. Stiffness is low, and speed can be very high with high life.
    01-flexure bearing-air bearing-frictionless bearing
    Reducing friction in bearings is commonly important for efficiency. It helps to cutback the wear and tear and to facilitate extended use at high speeds and to avoid heating and premature failure of the bearing. Friction of a control depends on its form, material, and fluid used between two surfaces applied on bearings. Completely different bearing operative have different operational speed limits. Plain bearings generally handle only lower speeds. However the gap between the components that are separated by the bearing varies with load. Forces working on the bearing may be radial, axial or bending moments perpendicular to the most axis.
    Next topic will be investigated distortion of bearings according to their types.