System hierarchy

In this framework hazard assessment is mainly based on toxicity testing in clean laboratory conditions. Findings of laboratory studies are then extrapolated to higher levels of natural system hierarchy (from organisms to communities and even ecosystems) using various factors (Smrchek and Zeeman, 1998). 

Level five is generally called the hub. This is the highest level in the system hierarchy and is applicable to organisations which coordinate the operations of a number of plants often distributed over a large geographical area. Examples are oil companies, pulp and paper companies, the water and gas industries, etc. 

A simple example of scoping constraint is the limitation of authorizations that can be stated by a policy to a specific portion of the data system hierarchy [15]. 

The hierarchical portion of HPDP refers to the different levels of scale that are operational in ecological systems. Hierarchy does not imply that the controlling factors are operating in a top-down or bottom-up fashion but that the level of scale is important in understanding the factors controlling ecological functions. In order to make predictions about one level of the hierarchy, it is critical to understand the contributions from factors at the levels of scale just above and below. 

The MES concept describes an area of functionality rather than a specific type of system, namely the area in a classical system hierarchy between high level planning systems (MRP II systems or ERP systems) and shop floor control (which includes both manual and automated process control systems). MES systems support manufacturing processes by providing planning, execution and reporting functions. 

System elements are subsystems, which even consist of sub-subsystems. This makes it possible to describe manufacturing as a multi-hierarchical socio-technical system (Westkamper 2007). The levels of the system hierarchy are ... 

The elements are integrated in an information and communication system which supports the operations with necessary instructions and process plans. Analytics for optimizariMi are competences inside of the elements and in the system hierarchy. 

Although the philosophy of system hierarchy is not new, there is no common industry standard. Design Organisations are thus encouraged to clearly define and agree a hierarchy with all stakeholder involved in... 

To facilitate the FHA (in terms of system hierarchy and interrelated functionality), it is recommended that functional trees (see examples in Fig. 3.5 and 3.6) are constructed to show the tiered relationship between aircraft functions and/or system component functions. Functional trees, while deceptively simple to look at, are in fact quite tricky to compile, and for complex systems, such trees may fail to adequately communicate or portray complex functional interaction. In some cases the assessor may elect to supplement these trees with additional data such as the example matrix in Table 3.1. 

During the Functional Development Phase, requirements for functions are developed and allocated to each level in the system hierarchy (down to items). These requirements need to be validated at eadi level, and the rigour is defined via the FDAL approach in ARP4754A Appendix A. FDAL validates die functional requirements. 

The FMEA is performed by postulating the ways the chosen level s specific implementation may fail. So, with reference to the example system hierarchy in Eig. 1.1, we can consider that ... 

Requirements Allocation is the process of ensuring that all requirements are assigned to each level of system integration. All requirements (including the allocated FDAL) are cascaded down the system hierarchy and, along with the derived equipment, provide the contents of the applicable system-level specifications (see Fig. 1.3). 

Figure 2.6-6 Ventilation System Hierarchy for Cascade Shutdown.2-39...

A system is typically composed of related elements (subsystems and components) and their interfaces. Additionally, elements include the people required to develop, produce, test, distribute, operate, support, or dispose of the element s products, or to train those people to accomplish their role within the system. Figure 1 provides a hierarchy of names for the elements making up a system. This generic system hierarchy is a key concept within this standard because it ties the system architectures, specificahon and drawing trees, system breakdown structure (SBS), technical reviews, and configuration baselines together. Many elements within the system hierarchy can be considered a system by the classical definition, but actually represent subsystems within the system hierarchy. Likewise, the life cycle processes represent subsystems within the overall system hierarchy. 

The human elements are integral to the systems hiraarchy, and may be present at any level. The human elements are not identified in the system hierarchy since the intent of the hierarchy is to identify the system element for which the system is being defined, and the human/system integration issues should be addressed in terms of the human s role in operating, producing, supporting, etc., the system. 

The use of the source control system, in combination with the system hierarchy within iQT, allows for a Hhrary function in which changes in the master library can be applied to models relying on those hbraries. This allows users to update the library incorporated in a project in an automated fashion. 

Data acquisition for process information, and the interface to process actuators, utilizes the simplest types of microprocessors, whereas the top level of the I C system hierarchy uses powerful minicomputers, eg., for core calculations. Intermediate types of microcomputers are utilized for control and operation, logic and signal treatment. 

An EtE flow latency analysis requires the specifications of EtE flows. An EtE flow reptresents a logical flow of information from a source to destination passing through various system components. It is defined in the component implementation (typically in the top level component in the system hierarchy) and refers to the specifications of other flows in the... 

Within a systems hierarchy [Faulkner 2002, Storey 2003], data is exchanged across external interfaces, and across internal interfaces. In such a hierarchy, data may be used within several layers. Each system component may use this common data in a different context and hence re-used data may be also attributed a subtly different meaning for each usage. The layered model [Faulkner 20021 allows the visualisation of the extent of the influence of these data structures, data elements or data items. This visualisation may identify a requirement for validation at an interface to preserve the integrity of one or more safety functions. 

The data architecture including the plication, stem and enterprise data architectures as the same data may be used (and re-used) by several systems within the systems hierarchy. Each stem may interpret this data and attribute to it subtly different meanings ... 

The controls to be applied to the possible propagation of data errors across the system hierarchy. These controls might include specific requirements for the verification of data at the system boundary. 

The system level safety arguments should address the use of the stem within the system hierarchy model, the coupling between sterns and the interaction of one or more systems under a range of operational conditions. These operational conditions should include the degraded modes of one or more of the applications. 

The use of configurable systems, particularly data-driven system requires an extensive series of safety arguments. These safety argument need to address the application and its context within the systems hierarchy paying particular attention to data passed between systems of differing integrity and across the systems boundary. 

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