SCALE device configuration

Nanometer scale domain configurations in fe bulk crystals pave the way for a new class of photonic devices. As an example, preliminary calculations show that a uv laser (A = 300 nm) based on second harmonic generation in LiTaC>3 crystal requires a periodic nanodomain superlattice with domain widths of around 700 nm. In addition, the current domain gratings in ferroelectric crystals are suitable only for quasi-phase-matched nonlinear interactions in the forward direction, where the pump and generated beams propagate in the same direction. Sub-micron ferroelectric domain gratings are the basis for a new family of devices based on backward nonlinear quasi-phase-matched optical interactions in which the generated beam travels in a reverse or another non-collinear direction to the incident beam. Non-collinear... 

Filters are available in several constructions, effective filtration areas, and configurations. Depending on the individual process, the filter construction and setup will be chosen to fit its purpose best. Most commonly used for RO filters are tubular devices, so-called spiral wound modules due to the spiral configuration of the membrane within the support construction of such device. UF systems can be found as a spiral wound module, a hollow fiber, or a cassette device. The choice of the individual construction depends on the requirements and purposes towards the UF device. Similar to the different membrane materials, UF device construction has to be evaluated in the specific applications to reach an optimal functioning of the unit. Microfilters and depth filters can be lenticular modules or sheets but are mainly cylindrical filter elements of various sizes and filtration areas, from very small scale of 300 cm to large scale devices of 36 m. A 10-inch high cylindrical filter element can be seen in Fig. 6. 

The single-layer devices, the bilayer devices (with and without the PAN-CSA network electrode), and the inverted devices discussed are unipolar devices operating under a single-bias condition. We now discuss two novel device configurations that can be operated in both forward and reverse dc biases as well as in ac modes the SCALE devices and color-variable bipolar/ac light-emitting devices. 

Symmetrically Configured AC Light-Emitting (SCALE) Devices... 

In the discussions of these approaches below, schematics of representative device configurations are included, accompanied by the basic device band structures to indicate the energetic driving forces behind the photolytic water splitting. Some examples of implementation in laboratory-scale prototypes are also presented. 

Although many CO lasers have employed the subsonic flow configuration of Figure 3.5, supersonic devices have also been operated/ °° Supersonic flows would be desirable in large-scale devices with power outputs exceeding approximately 1 kW. 

Cathodic protection is a useful supplement to other forms of water treatment, as a general corrosion inhibiting device in HW boilers, or where specific design configurations can lead to inadequately protected localized metal in steam boilers. Where BW makeup demands are minimal and boiler output is fairly constant, cathodic protection devices can also provide some measure of protection against hardness scales. Calcium carbonate salt is formed as a floc-culant or soft sludge rather than a hard scale, due to the peptizing effects of a zinc hydroxide complex formed from zinc ions in alkaline BW. 

Cross-flow is the usual case where cake compressibility is a problem. Cross-flow microfiltration is much the same as cross-flow ultrafiltration in principle. In practice, the devices are often different. As with UF, spiral-wound membranes provide the most economical configuration for many large-scale installations. However, capillary devices and cassettes are widely employed, especially at smaller scale. A detailed description of cross-flow microfiltration had been given by Murkes and Carlsson [Crossflow Filtration, Wiley, New York (1988)]. 

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