Drawing Boundaries for Air Quality Control Under the Clean Air Act: The Importance of NOT Being Nonattainment

Much has changed with regard to air pollution control since 1970 whenCongress revised the Clean Air Act to assume a form that, in very broad terms,it retains today.  From a legal point of view, while states1 still retained at thattime wide-ranging discretion to design the regulatory controls necessary toattain the air quality goals of the Act, that discretion was significantly limitedwhen Congress revisited the Act in 1977.  State discretion diminished to aneven greater extent, particularly with regard to the air pollutants ozone, carbonmonoxide, and particulate matter, when President George H.W. Bush signedthe Clean Air Act Amendments of 1990.</jats:p

Comparison of Hydrogen Ion Concentration Results in Silicic Acid Gel Mixtures by Different Methods

Since a conclusive theory of the structure of gels has not been presented yet, it is still necessary to obtain as much data about gels as possible, in the hope that the assembled data will lead to a theory which will explain all the known facts. Thus, the effect of such factors as temperature, concentration of acis and the addition of indicators were studied. Also, the change of the properties of viscosity and conductivity during the time of set were studied

Approaches to Three-Dimensional Transformation Optical Media Using Quasi-Conformal Coordinate Transformations

We introduce an approach to the design of three-dimensional transformation optical (TO) media based on a generalized quasi-conformal mapping approach. The generalized quasi-conformal TO (QCTO) approach enables the design of media that can, in principle, be broadband and low-loss, while controlling the propagation of waves with arbitrary angles of incidence and polarization. We illustrate the method in the design of a three-dimensional "carpet" ground plane cloak and of a flattened Luneburg lens. Ray-trace studies provide a confirmation of the performance of the QCTO media, while also revealing the limited performance of index-only versions of these devices