Control independent

Relationships from thennodynamics provide other views of pressure as a macroscopic state variable. Pressure, temperature, volume and/or composition often are the controllable independent variables used to constrain equilibrium states of chemical or physical systems. For fluids that do not support shears, the pressure, P, at any point in the system is the same in all directions and, when gravity or other accelerations can be neglected, is constant tliroughout the system. That is, the equilibrium state of the system is subject to a hydrostatic pressure. The fiindamental differential equations of thennodynamics ... 

Electric heat provided by a resistance or by an electric arc can be substituted for the burning of a fuel. Electric furnaces can be designed in a variety of shapes and are more versatile than fuel-heated furnaces. The furnace atmosphere can be controlled independently of the chemistry of the combustion... 

Provide manual backup—control independent of software... 

The use of a polymeric support also affords a unique opportunity to control independently the variables that may affect the chiral recognition process, which is hard to achieve with silica. For example, the type and number of reactive sites can be easily adjusted with a polymer support. We recently reported an extensive study of the... 

Fig. 1-2. Schematic diagram of the Coolidge (high-vacuum) x-ray tube. Coolidge tubes are widely used because they are stable and long-lived and permit tube current and voltage to be controlled independently.

The design equations for a CSTR do not require that the reacting mixture has constant physical properties or that operating conditions such as temperature and pressure be the same for the inlet and outlet environments. It is required, however, that these variables be known. Pressure in a CSTR is usually determined or controlled independently of the extent of reaction. Temperatures can also be set arbitrarily in small, laboratory equipment because of excellent heat transfer at the small scale. It is sometimes possible to predetermine the temperature in industrial-scale reactors for example, if the heat of reaction is small or if the contents are boiling. This chapter considers the case where both Pout and Tout are known. Density and Q ut wiU not be known if they depend on composition. A steady-state material balance gives... 

Temperature and composition of the gas phase cannot be controlled independently the partial pressures are determined by the temperature and the physical properties of the reaction mixture, and thus they vary with time. 

Thus, large let-down flows are usually seen to be a missed cogeneration opportunity but might provide a degree of freedom to bypass bottlenecks in the steam system. Also, flow through let-down stations allows the level of superheat in the lower-pressure mains to be controlled independently of the flow through the steam turbines. 

Figure 5.4 Electric circuit for in situ STM, which allows sample and tip potentials to be controlled independent from each other.

Itaya and colleagues decided to employ STM to see if any correlation existed between the surface topography and the electrochemistry in Figures 2.27(a) and (b). The images were obtained at constant current with the tip and sample controlled independently. 

Consequently, ions such as BF4 and PFf), which might be expected to complex or solvate an electroactive metal species, are not expected to be reduced and to influence alloy composition, unlike AICI4 and A ECU. In principle, this should lead to better control of alloy composition since the concentrations of the electroactive species may be controlled independently. For example, one can avoid an electroactive species such as [Ti(AlCl4)3] which is likely responsible for the limited composition range found in Ti-Al alloys electrodeposited from chloroaluminates. 

Furthermore for the relevant adsorption steps CO-adsorption, H O-adsorption, CC -desorption, H -desorption, one concludes from the form of the transients that tne first three are not kinetical-ly controlled, as they are shock fronts and that Hj has no measurable sorption capacitance in presence of CO. The last conclusion has been also confirmed by independent experiments, i.e. strip-ping-off of adsorbed H by CO, and the transients in this case suggest that also the desorption, at least under the selected experimental conditions, is not kinetically controlled. Independent transient experiments showing that the CO2 sorption transients can have the form of shock wavefronts or simple wavefronts (see (7)) support the conclusion that CO2 sorption is not kinetically controlled it could be also shown that 1 0 can strip off... 

The two compartment trough is schematically shown in Fig. 12. The trough is divided to two large compartment, where monolayer is spread, and a small buffer portion by two fixed barriers with a flexible gate. Compression of monolayers spread on each compartment is controlled independently by two movable polytetrafluoroethylene (PTFE) barriers. A substrate can move from a compartment to the other compartment by passing through the flexible gates... 

Along with hydrophobicity, large amounts of both water (to promote hydrolysis) and methanol employed as co-solvent in the catalyst preparation (to promote homogeneity) are needed to ensure optimal reactivity, showing the number of experimental parameters of the sol-gel synthesis which can be controlled independently to optimize the performance of the resulting catalyst. Finally, in contrast to zeolites and other crystalline porous materials, amorphous sol-gel materials show a distribution of porosity which does not restrict the scope of application of sol gel catalysts to substrates under a threshold molecular size. 

Upon mixing, the polar sol-gel droplets are dispersed in the non-polar solvent and act as micro-reactors in which the gelation proceeds, yielding microparticles with size comparable to that of the droplets. Thus, one can control independently the particle size by controlling the... 

Further elaboration of these dendrigraft principles allowed the synthesis of a variety of core-shell type dendrigrafts, wherein elemental composition as well as the hydrophobic/hydrophilic character in the core can be controlled independently. 

The schematic diagram of the system is shown in Fig. 3—4. An electrochemical cell is connected to the recipient chamber, whose vacuum is controlled independently using a turbo pump located just below it. A small... 

The rate of electrochemical reactions is given by the cell current, that is, in principle, it can be controlled independent of the temperature (the required overvoltages are influenced by the temperature, however). But usually, electroorganic conversions include chemical reaction steps and therefore the temperature influence, especially on reaction kinetics and selectivity, is frequently similar to that of pure chemical reactions. Consequently, a constant temperature is desirable to achieve clearly defined conditions for the investigations. 

For capillary zone electrophoresis (CZE) mass spectrometry coupling, another modification of an ESI interface has been developed. This interface uses a sheath flow of liquid to make the electrical contact at the CZE terminus, thus defining both the CZE and electrospray field gradients. This way, the composition of the electro sprayed liquid can be controlled independently of the CZE buffer, thereby providing operation with buffers that could not be used previously, e.g., aqueous and high ionic strength buffers. In addition, the interface operation becomes independent of the CZE flow rate. [62]... 

The pore size of the membrane could also be controlled independently of the porosity by altering the size of the salt particles (Fig. 5a). Membranes with high surface area/volume ratios were produced and the ratio was dependent on both salt weight fraction and particle size (Fig. 5b). In addition, the crystallinity of PLLA membranes can be tailored to that desired for each application. These characteristics are all desirable properties of a scaffold for organ regeneration. The major disadvantage of this technique is that it can only be used to produce thin wafers or membranes (up to 2 mm in thickness). A three-dimensional scaffold cannot be directly constructed. This problem may be circumvented however, by membrane lamination. 

Although more expensive than melt fiberization, the sol processes offer advantages in fiber chemistry selection. In melt fiberization, viscosity and surface tension are gready influenced by additions of small quantities metallic oxides. In the sol process, where viscosity can be controlled independently, any number of metal salts may be added without adverse effects. These salts can serve as grain growth inhibitors, sintering aids, phase stabilizers, or catalysts. 

In general, the process conditions that can be selected and controlled independently during filament winding are ... 

---