Application Task

Each step in the process shonld serve to focus your attention on the techniques that best suit the requirements of the analytical task. Let us take a closer look at these steps. 

In this step, the analytical objective should be broadly defined. For example, what is the concentration of iron in high-purity hydrochloric acid, or how much arsenic is in contaminated soil However, it is important not to lose sight of what you are actually trying to accomplish with this analysis. In other words, for the previous example, one should not forget what decisions wiU be made based on knowing the trace element composition of the sample. Before proceeding to specifics, you should have a basic understanding of your objective when you finish the evaluation of several different analytical techniques. Once that has been done, one can proceed to focus on the techniques that could possibly accomplish this task. 

Compiling performance criteria helps make clear the right techniques for the task. The field should now be narrowed down to establish a set of practical criteria, which might eliminate some of the less suitable techniques for a particular application. Some of these criteria will include (but not be limited to) detection limits, precision requirements, quality of data, sample throughput capability, ease of use, instrument reliability, operator training needs, or availability of application material. 

This will include information about the elemental requirements, such as what detection limits and concentration ranges are expected, and how much accuracy and 

Installation factors might include the size of the instrument, how much laboratory space is required, what services are necessary, or how clean the laboratory and the sample preparation environment should be. As mentioned in Chapter 15, this is a major consideration if ICP-MS is the technique of choice. 

By rigorously defining the task, it will become relatively clear what techniques to evaluate. By comparing and contrasting the attributes of each of the techniques, one begins to appreciate the value of each and starts determining how the instrumentation 

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High polarity is one of the reasons why both the ionic and amphoteric surfactants, and especially their metabolites, are difficult to detect. This property, however, is important for the application tasks of surface-active compounds, but is also the reason for their high water solubility. Due to this fact, their extraction and concentration from the water phase, which can be carried out in a number of very different ways, is not always straightforward. Furthermore, they are often not volatile without decomposition, which thus prevents application of gas chromatographic (GC) separation techniques combined with appropriate detection. This very effective separation method in environmental analysis is thus applicable only for short-chain surfactants and their metabolites following derivatisation of the various polar groups in order to improve their volatility. 

After jet merging, the material is brought out by an air stream, which redirects the merged stream by 90° into an outlet tubing [52,166], This is particularly done because a major application task of the mixer is to perform precipitation reactions. In the latter case, the mixed fluid is sprayed as small droplets or particles. If the droplets still contain solvent, nanoparticles can be produced by evaporation. 

The cognitive demands of the application task (e.g., knowledge, required information-processing activities, speed, and accuracy in performance actions)... 

FIGURE 81.1 The user s purpose is served by the application task, which is accomplished through the interaction task. 81.4.1.5 Task Analysis, Allocation, and Modeling... 

The concept of optimal usability is more complex. An optimized design will allow users maximal use of their performance and skill resources, allocated at their discretion to the apphcation task, to maximize their performance on the application task. Thus an optimal design minimizes the resources required to perform the interaction task and enhances the utiKty of the user s resources in performing the apphcation task. This means that the interface will support the user in performing the portion of the apphcation task allocated to the user. This is accomphshed through apphcation-level design issues associated with the organization and level of objects, actions, and information. 

Successful HCI design decisions must be made on the basis of (1) knowledge about the user s performance and skill resources, (2) the performance and skill resource requirements of the application task, and (3) the performance capabiHties of available technology. 

Application task Refers to the objectives the user is employing the product to accomplish. Human-centered design Human-centered design refers to a philosophy of human-machine system design that places the focus of the design process on the needs of the human who uses the system... 

Tasks are goal-directed patterns of action performed to achieve human purposes. Tasks are delineated at different levels with respect to their defined goals and their contribution to satisfying a purpose. Low-level tasks combine to accomplish higher-level tasks. Figure 33.1 delineates two tasks at distinct levels an application task and an interaction task. 

In Figure 33.1, both the human and product functionally contribute to and work together in performing the application task. The functions and lower-level tasks needed to perform the application task are distributed between them. This distribution, known as allocation, is based on the capabilities and limitations each possesses. The allocation of function is a major factor in determining the interactions between the human and product that need to be performed. 

Both application tasks and interaction tasks may be described at multiple levels. For example, the application task of reviewing a medical record may involve the lower-level application task of retrieving the record from an electronic database. The retrieval task, in turn, may entail a still lower-level... 

FIGURE 35.1 Each user group s purpose is satisfied by one or more application tasks that are accomplished through the interaction tasks performed among the users and systems. 

Because, as in the example in Figure 35.1, humans and biomedical systems work together to satisfy the apphcation tasks, the resources needed to accomplish the tasks are distributed between the humans and the machine systems. The designer has partial control over the resources required of the user to perform the interaction and application tasks by optimally olf-loading (i.e., allocating) required resources to the machine systems. Figure 35.2 illustrates the resource correspondence between the users and machines. The arrows indicate the flow of information across the interface (Figure 35.2). 

In resource terms, applying this design principle increases the fit between an individual user s available mental and physical resources and those required by the interaction and application tasks. There are two major dimensions on which users vary experience and capability. 

Sequence Language. This facility allows creation of sequences of commands to automate application tasks. Branching, variables, prompting, and menu control operations are among the capabilities. Almost all of the commands from other facilities may be included in a sequence. 

The broad key finding can be simply summarized there is no general micro-fluidic control tool yet instead it is necessary to phrase each application task as a tractable control-design mathematical question, to find an implement an answer, and then to validate this answer experimentally. 

CAST. Ionizing energy in food processing and pest control II. Application. Task Force Report No 115. Council for Agricultural Science and Technology, Ames, Iowa., 1989. 

Design strategies for achieving usability follows from an analysis of available and required resources and application of HCI design principles that act to reduce resource task demand on users. For example, usability will tend to increase as the resources required of the user to perform the interaction and application tasks decrease. Usability wiU tend to increase as interface resource availability of the resources increases. 

A second performance-based design objective is to apply HCI resources to optimize the resources the user needs to perform the application task. Many of the objects, actions, and information with which the user interacts are application-task-specific. Organization and representation decisions should be based on these task-specific requirements. For example, if the application task involves drawing, the user needs general software and hardware drawing tools and devices. 

The problem inputs are a task data flow graph which specifies the overall application task including the set of subtasks (nodes) to be executed, the data precedence requirements (arcs) and the volumes of data to be transferred between the subtasks a set of processing elements with varying functionality, cost and performance communication link characteristics with its cost and performance constraints on total system cost and constraints on timing of arbitrary events in the task execution. 

Abstract. In recent years, deductive program verification has improved to a degree that makes it feasible for real-world programs. Following this observation, the main goal of the BMBF-supported Verisoft XT project is (a) the creation of methods and tools which allow the pervasive formal verification of integrated computer systems, and (b) the prototypical realization of four concrete, industrial application tasks. 

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