2. virtual reality (VR) or virtual environment (VE), computer-generated environment with and within which people can interact. It is an artificial environment that is created with software and presented to the user in such a way that the user suspends belief and accepts it as a real environment. The advantage of VR is that it can immerse people in an environment that would normally be unavailable due to cost, safety, or perception restrictions. A successful VR environment offers users immersion, navigation, and manipulation. Some of the more realistic effects are achieved using a helmet like apparatus with tiny computer screens, one in front of each eye and each giving a slightly different view so as to mimic stereoscopic vision. Sensors attached to the participant (e.g., gloves, bodysuit, footwear) pass on his or her movements to the computer, which changes the graphics accordingly to give the participant the feeling of movement through the scene.

3. Computer-generated physical feedback adds a "feel" to the visual illusion, and computer-controlled sounds and odors reinforce the virtual environment. Other VR systems, such as flight simulators, use larger displays and enclosed environments to create an illusion. Less- complicated systems for personal computers manipulate an image of three-dimensional space on a computer screen. In a virtual network many users can be immersed in the same simulation, each perceiving it from a personal point of view. VR is used in some electronic games, in amusement-park attractions, in military exercises, and to simulate construction designs. Experimental and envisioned uses include education, industrial design, surgical training, and art.

4. Virtual manufacturing (VM) may play a significant role in distributed manufacturing, since it may improve design critiquing and process planning. These improvements will result in better designs and more informed partner selection. Furthermore, VM is expected to support distributed design if it provides protocols and computer aids for negotiation.

6. Design-Centered Production-Centered Control-Centered Evaluating the manufacturability of a proposed design involves determining whether or not it is producible with a given set of manufacturing operations---and if so, finding the associated manufacturing efficiency. Distributed manufacturing is performed by virtual enterprises. A virtual enterprise is a partnership of companies that forms in response to a certain market opportunity. The partners, who may geographically distributed and of various sizes and technical sophistication, contribute their core competence to the enterprise, enhancing its ability to deliver high quality, cost effective products to the market in a timely fashion. Distributed design is performed by multiple designers who may be distributed geographically and who employ heterogeneous design support systems. Addition of simulations to control models and actual processes, allowing for seamless simulation for optimization during the actual production cycle.

7. New product development (NPD) Advanced planning and scheduling (APS), Computer-aided manufacturing (CAM), Computer-aided production engineering (CAPE), Computer-aided production planning (CAP/CAPP), Manufacturing execution systems (MES), and Manufacturing process management (MPM)

8. a) Styling b) Concept Design c) Ergonomics d) Design Review e) Virtual Maintenance g) Virtual Training

9. a) Styling b) Concept Design c) Ergonomics d) Design Review e) Virtual Maintenance g) Virtual Training

10. a) Styling b) Concept Design c) Ergonomics d) Design Review e) Virtual Maintenance g) Virtual Training

11. a) Styling b) Concept Design c) Ergonomics d) Design Review e) Virtual Maintenance g) Virtual Training

12. a) Styling b) Concept Design c) Ergonomics d) Design Review e) Virtual Maintenance g) Virtual Training

13. a) Styling b) Concept Design c) Ergonomics d) Design Review e) Virtual Maintenance f) Virtual Manufacturing g) Virtual Training

14. Work Area 2 Work Area 1 Work Area 3 Sales 2 Factory 2 Sales 1 Factory1 Customer 3 Customer 2 Customer 1 Company 1 Company 2 supplier1 supplier2 supplier3 Multi Enterprise Layer Enterprise Layer Shop Floor Cell Layer Company 2 } VR is applicableat these 3 layers

15. Sales 2 Factory 2 Sales 1 Factory1 Enterprise Layer Detail planning and building of the production system (Delmia example) Previous planning results are detailed 6 manual work stations are realized. Results of detailed planning: Estimated costs for engine are not exceeded. The cycle time is reduced to 105 seconds. Ergonomic analyses Detailed layout planning Simulation Detailed time analyses 3D Process Verification

16. Work Area 2 Work Area 1 Work Area 3 Shop Floor The purposed design and processes can be simulated directly in the virtual environment in order to verify applicability of the proposal

17. Cell Layer VR can also directly simulate the cells which are the machines for example a CNC machine can be programmed and tested virtually prior the real action for verification.

19. VM Constitution