Coal mining generates significant adverse environmental impacts. Historically, coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one. Underground mining hazards include suffocation, gas poisoning, roof collapse and gas explosions.
The term 'OVD' (Optically Variable Device) is used to describe both laser generated hologram images and electron beam generated images. These optically variable devices are created in highly-secure facilities and are at the forefront of overt asset and brand protection programmes.
dinCloud Explains HVD & How It Works. HVD or hosted virtual desktops are the next phase in IT efficiency and productivity gains. Similar to how organizations virtualized servers, HVD refers to the virtualization of the desktop. This illustration below shows how a single server can support multiple virtual desktops.