What is an Interface

What is an interface To answer this essential question, first consider the molecular nature of the phases involved. Assume that the system in question has a simple structure and contains only two components, A and B. The molecular interaction between components A and B will ultimately determine the overall structure of the system. Three particular... 

With consideration of surface properties as a function of the contacting phase or the surrounding medium, two serious questions arise (1) what is a surface and (2) what is an interface In recognition of the fact that surface properties... 

A. For an alloy of 0.05% Si, what is the interface temperature for steady-state freezing ... 

There have been numerous studies employing calorimetric(19), dynamic mechanical, ( ) dielectric, ( ) and morphological(23,24) techniques to elucidate the solid-state behavior of styrene-ethylene oxide block copolymers. These measurements have focused on transition-temperature phenomena, and they have provided reference data on the bulk properties of the copolymers. The evidence accumulated to date indicates that PS and PEO are incompatible in the bulk. While this appears true, in general, one cannot rule out the possibility that PS and PEO have some limited degree of miscibility in the copolymers. It is also unknown, at this time, what influence an interface (e.g., the air-polymer interface) has... 

We have considered the thermal boundary-layer problem in this chapter for an arbitrary 2D body with no-slip boundary conditions for Re 1 and Pr (or Sc) either arbitrarily large or small. If we assume that we have a body of the exact same shape, but the surface of which is a slip surface (e.g., it is an interface, so that the surface tangential velocity is not zero), the form of the correlation between Nusselt number and Pr will change for Pr 1. Solve this problem, i.e., derive the governing boundary-layer equation, and show that it has a similarity solution. What is the resulting form of the heat transfer correlation among Nu, Re, and Pr ... 

From the materials point of view the surface of a solid can in a simple way be defined as a discontinuity in a lattice pattern. More precisely, a discontinuity in a lattice pattern is an interface. For example, the surface of a metal in a vacuum should be called the solid/ vacuum interface. The inner surface of a glass fish bowl filled with water should be called the glass/water interface. When we designate the interface simply as the surface of the solid we usually presume that what exists on the other side of the interfacial boundary has no effect on the solid at the interface. Sometimes this assumption is valid insofar as can be detected at other times the "environment" does affect the properties of the solid side of the interface. 

A system is a part of the universe within a certain domain in space and time. What is an environment Outside the frontier of the system is the environment [1], Here, system shall have an identity, that is, deterministic. There shall be an external boundary to the system. An external boundary is determined by what aspect of system performance is of concern. This is stated here because for quantitative hazard analysis, boundary definition is extremely important. Also, the interface part needs to be considered (See Fig. V/3.0-l). The process definition for qualitative risk analysis is Qualitative Risk Analysis assesses the priority of identified risks using their probability of occurring, the corresponding impact [...] as well as other factors such as the time frame and risk tolerance [..On the contrary, quantitative risk analysis (QRA) as per DNV is Typically, a QRA can be defined as the formal and systematic approach of identifying potentially hazardous events, estimating the likelihood and consequences of those events, and expressing the results as risk to people, the environment or the husiness. ... 

Current spreadsheet programs contain many advanced capabiUties and enhancements that an engineer might want to use they also offer improved performance, interfaces to data base and word-processing programs and have a host of other features. A good overview that describes the features and presents what is available in each of the latest spreadsheet packages on the market is available (78). 

For systems where the bulk freezing transition is well understood, one may want to go one step further and investigate the modifications of the phase transition and the sohd phases in the event of external influence on the system. Flow does freezing happen in a confined situation where external boundaries are present What is freezing in porous media like A related question is What does the interface between sohd and liquid look like This is an intrinsic inhomogeneity that the system builds up by itself (if, as usual, the transition is first order). Let us describe some papers dealing with freezing under external influence. 

In a packed column, operating at approximately atmospheric pressure and 295 K, a 10% ammonia-air mixture is scrubbed with water and the concentration of ammonia is reduced to 0.1%. If the whole of the resistance to mass transfer may be regarded as lying within a thin laminar film on the gas side of the gas-liquid interface, derive from first principles an expression for the rate of absorption at any position in the column. At some intermediate point where the ammonia concentration in the gas phase has been reduced to 5%. the partial pressure of ammonia in equilibrium with the aqueous solution is 660 N/nr and the transfer rate is ]0 3 kmol/m2s. What is the thickness of the hypothetical gas film if the diffusivity of ammonia in air is 0.24 cm2/s ... 

A solute diffuses from a liquid surface at which its molar concentration is C, into a liquid with which it reads. The mass transfer rate is given by Fick s law and the reaction is first order with respect to the solute, fn a steady-state process the diffusion rate falls at a depth L to one half the value at the interface. Obtain an expression for the concentration C of solute at a depth z from the surface in terms of the molecular diffusivity D and the reaction rate constant k. What is the molar flux at the surface ... 

In this chapter it has been shown that what happens as an interface is formed is directly measured by AX as derived from Ea=o vs. 0 plots. AX... 

Mass Transfer Rates. Mass transfer occurs across the interface. The rate of mass transfer is proportional to the interfacial area and the concentration driving force. Suppose component A is being transferred from the gas to the liquid. The concentration of A in the gas phase is Ug and the concentration of A in the liquid phase is u . Both concentrations have units of moles per cubic meter however they are not directly comparable because they are in different phases. This fact makes mass transfer more difficult than heat transfer since the temperature is the temperature regardless of what phase it is measured in, and the driving force for heat transfer across an interface is just the temperature difference Tg—Ti. For mass transfer, the driving force is not Ug—ai. Instead, one of the concentrations must be converted to its equivalent value in the other phase. 

An ion-selective electrode contains a semipermeable membrane in contact with a reference solution on one side and a sample solution on the other side. The membrane will be permeable to either cations or anions and the transport of counter ions will be restricted by the membrane, and thus a separation of charge occurs at the interface. This is the Donnan potential (Fig. 5 a) and contains the analytically useful information. A concentration gradient will promote diffusion of ions within the membrane. If the ionic mobilities vary greatly, a charge separation occurs (Fig. 5 b) giving rise to what is called a diffusion potential. 

A pipe carrying water is inclined at an angle of 45° to the horizontal. A manometer containing a fluid with an SG of 1.2 is attached to taps on the pipe, which are 1 ft apart. If the liquid interface in the manometer leg that is attached to the lower tap is 3 in. below the interface in the other leg, what is the pressure gradient in the pipe (AP/L), in units of (a) psi/ft and (b) Pa/m Which direction is the water flowing ... 

To extract useful results from a molecular electronic device, or just to measure its electronic characteristics, connections must be made to macroscopic probes. That is, metallic electrodes must interface to different ends of the molecule of interest. An experiment may interrogate a single molecule, or may measure a one-molecule-thick layer, i.e., a monolayer, of the molecules of interest, provided all the molecules are oriented in the same direction. In either case, several questions arise. What is the nature of the contact between metal and molecule(s) What metal should be chosen, and what should be the form or shape of this electrode ... 

In Catalysis, we characterize behavior using type definitions, attaching postconditions to the operations. In Java, the corresponding construct is the interface Classes that implement an interface must provide the listed operations. Wise interface writers append comments specifying what clients expect each operation to do, and classes that claim to implement the interface should conform to those specifications even though each will do so in its own way. In C++, the pure abstract class plays the role of the Java interface in design. 

Refining an action is like devising an interface standard for the signals on a video connection. You must involve all the designers who might make a box to go on either end of this connection—or at least all those you know at the moment. You must agree to a specification for what is achieved and then refine it to a set of signals that, in some parallel or sequential combination, achieves the overall required effect. 

In addition to the underlying mechanisms being shared, components must agree on the definition of problem domain terms—usually manifested as problem domain objects—on which they will jointly operate. Components in a medical information system, for example, must share a common definition of what exactly a Patient is and what constitutes an Outpatient Treatment. They must share this definition at least in terms of the interfaces of those objects. 

COM does not have the equivalent of Java s reflection, relying instead on the type library. Consequently, scripting and other applications that require very late binding—in which even the method called is not compiled against an interface but is looked up at runtime—require explicit support in the component itself. Each component can support what are called dispatch interfaces, in which a client requests an operation by a number the component resolves the mapping from numbers to methods to invoke. COM uses outgoing interfaces to define events, just as JavaBeans uses its events. 

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