| Acronym | Meaning |
![](file.png) | NWRI | National Water Research Institute (Burlington |
![](file.png) | NWS | National Weather Service |
![](file.png) | NWSIA | National Water Supply Improvement Association |
![](file.png) | NWWA | National Water Well Association |
![](file.png) | NWWA | Northwest Water Authority (UK) |
![](file.png) | NYSAS | New York Summer Aerosol Study |
![](file.png) | NYSDEC | New York State Department Of Environmental Conservation |
![](file.png) | NYSERDA | New York State Energy Research And Development Authority |
![](file.png) | NZRPA | Normalized Zero-range Potential Approxn. |
![](file.png) | O/E | Observed Number/expected Number Ratio = Relative Risk |
![](file.png) | OA | Office Of The Administrator |
![](file.png) | OAM | Optical Absorption Microscope |
![](file.png) | OAO | Orthogonalized Atomic Orbital |
![](file.png) | OAP | Optical Atom Probe |
![](file.png) | OAPP | Oxidized Atactic Polypropylene |
![](file.png) | OAQPS | Office Of Air Quality Planning And Standards |
![](file.png) | OAQPSTTN | Office Of Air Quality Planning And Standards Technology Transfer Network |
![](file.png) | OAR | Office Of Air And Radiation (USEPA) |
![](file.png) | OARM | Office Of Administration And Resources Management (USEPA) |
![](file.png) | OASCR | Office Of Advanced Scientific Computing Research |
![](file.png) | OASIS | Ocean And Atmospheric Sounding Interferometer System |
![](file.png) | OASLM | Optically Addressed Spatial Light Modulator |
![](file.png) | OAW | Oxyacetylene Welding |
![](file.png) | OB/OD | Open Burn/open Detonation |
![](file.png) | OBD | Optical Beam Deflection |
![](file.png) | OBD | On-board Diagnosis |
![](file.png) | OBDD | Ordered Bicontinuous Double-diamond |
![](file.png) | OBE | Optical Bloch Equation |
![](file.png) | OBIC | Optical Beam Induced Current |
![](file.png) | OBK | Oppenheimer-Brinkman-Kramers (approxn. In Atom-ion Electron-exchange Calcns.) |
![](file.png) | OBK2 | Second-order Oppenheimer-Brinkman-Kramers |
![](file.png) | OBK3 | Third-order Oppenheimer-Brinkman-Kramers |
![](file.png) | OBS-MCSC | Optimized Basis Set-multiconfiguration Spin Coupled |
![](file.png) | OC | Office Of The Comptroller |
![](file.png) | OC | Oxygen Consumed |
![](file.png) | OCAMS | Orbital Correspondence Analysis In Maximum Symmetry |
![](file.png) | OCAP | Open-channel Air Preheater |
![](file.png) | OCBSE | Orthogonality Constrained Basis Set Expansion Prodedure |
![](file.png) | OCC | Organochlorinated Compound |
![](file.png) | OCCSD | Open-shell Coupled-cluster (with) Single (and) Double (excitations) |
![](file.png) | OCD | Offshore And Coastal Dispersion (modeling Of Air Quality) |
![](file.png) | OCD | Overlapping Charge Density (model In Electronic Structure) |
![](file.png) | OCE | One-center Expansion (SCF MO Method) |
![](file.png) | OCE | Overall Control Efficiency |
![](file.png) | OCE-DF | One-center Expansion Dirac-Fock |
![](file.png) | OCEC | Open-channel Electrochromatography |
![](file.png) | OCEE | Overlap Corrected Electronegativity Equalization |
![](file.png) | OCEFT | Office Of Criminal Enforcement |
![](file.png) | OCEPA | Office Of Communications |
![](file.png) | OCH | Ochkur (approxn. In Electron-atom Scattering Calcns.) |