Interface design requirements

Sound user interface design requires engagement and close cooperation of representative users. In practice it is insufficient to simply hold a focus group to ask users what their requirements are. A better approach is to formally implement a user-centred design process. Here a small number of representative users are convened and comments are solicited on candidate designs. As the project progresses designers need to offer prototypes or test enviromnent for the subjects to try out the product. 

System specification proceeds much as before but has an added element of user-interface design. The normal artifacts of system specification—a type model and operation specs—are now accompanied by prototypes and UI specs describing the screens, dialog flows across windows, information presented and required, and reports. These user-interface elements are kept consistent with the type model and are reviewed through scenarios. 

A performance standard states requirements in terms of required results with criteria for verifying compliance but without stating the methods of achieving required results. A performance standard may define the functional requirements for the item, operational requirements, and/or interface and interchangeability characteristics. A performance standard may be viewed in juxtaposition to a prescriptive standard, which may specify design requirements, such as materials to be used, how a requirement is to be achieved, or how an item is to be fabricated or constructed (Office of Management and Budget 1998). 

The basic requirement for an interface is that the analytes should be maintained in the gaseous form during transport from a GC column to the plasma, in a way that any condensation is prevented. The interface designs were reviewed in detail [8]. A GC-ICP-MS interface is commercially available which indicates the recognition of the maturity of this coupling by manufacturers of analytical instrumentation. 

Human Machine Interfaces (HMls) required and their design... 

Topics to be discussed in this section include (1) instrument requirements, (2) instrument and operator interface design, (3) examples of POCT devices, and (4) the role of informatics. Readers requiring additional information are referred to more comprehensive texts or to the vendors of POCT devices. 

The user requirements specification, also referred to as requirements document or release plan, describes the requirements from an operator s point of view. This high-level document does not give any details about how the software actually is constructed, except that it may contain desired user interface designs to address a requirement. 

Hie application of this equation to design requires information ou concentrations at the interface which is seldom known. As a result, absorption data frequently are correlated in terms of overall coefficients. These are based on the total driving force from the main body of the gas to the main body of the liquid. The overall cnefficients Kg and K,. are defined try the ftoBowing reJatioaship ... 

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