{{project}} System Design Description

Introduction

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System Purpose

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Briefly describe the objectives and rationale of the System Design Description (e.g., describing the system design in the user's terminology, providing a guide for a more technical design document, or ensuring that customers and technical staff have a common understanding of the system design). Explain how this document might evolve throughout the product life cycle.

System Scope

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Delineate the following:

  1. Identify the product(s) to be produced by name (Network Infrastructure, Host DBMS, Report Generator, HPC Server, etc.)

  2. Explain what the product(s) will, and, if necessary, will not do.

  3. Describe the application of the product being specified, including relevant benefits, objectives, and goals.

note

Be consistent with similar statements in higher level specifications (e.g., business requirements specification).

Dependencies and Limitations

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List the dependencies or limitations that may affect the design of the system. Examples include budget and schedule constraints, staffing issues, availability of components, etc. Describe how each factor will affect the functional design.

References

  1. ISO/IEC/IEEE 24765:2010(E). Systems and software engineering—Vocabulary. first edition, December 15 2010.[BibTeX]
  2. ASME NQA-1. ASME NQA-1-2008 with the NQA-1a-2009 addenda: Quality Assurance Requirements for Nuclear Facility Applications. first edition, August 31 2009.[BibTeX]

Definitions and Acronyms

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This section defines, or provides the definition of, all terms and acronyms required to properly understand this specification.

Definitions

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Add or revise spcific defintions.

  • Baseline: A specification or product (e.g., project plan, maintenance and operations (M&O) plan, requirements, or design) that has been formally reviewed and agreed upon, that thereafter serves as the basis for use and further development, and that can be changed only by using an approved change control process (NQA-1, 2009).

  • Validation: Confirmation, through the provision of objective evidence (e.g., acceptance test), that the requirements for a specific intended use or application have been fulfilled (24765:2010(E), 2010).

  • Verification: (1) The process of: evaluating a system or component to determine whether the products of a given development phase satisfy the conditions imposed at the start of that phase. (2) Formal proof of program correctness (e.g., requirements, design, implementation reviews, system tests) (24765:2010(E), 2010).

Acronyms

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Define specific acronyms.

AcronymDescription
ASMEAmerican Society of Mechanical Engineers
DOEDepartment of Energy

Design Stakeholders and Concerns

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Design Stakeholders

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Identify the stakeholders of the IT system design.

Stakeholder Design Concerns

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Identify and address each design concern including measures to mitigate consequences of problems. Reference risk management plan as appropriate.

System Design

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For this section, detail should be commensurate with the level of risk and demonstrate the fulfillment of requirements providing guidance for implementation.

For custom developed software (see def. in LWP-13620) activities, the following is required:

The documented design shall include, as applicable:

  • Numerical methods

  • Mathematical models

  • Physical models

  • Control flow

  • Control logic

  • Data flow

  • Process flow

  • Data structures

  • Process structures

  • Applicable relationships between data structures and process structures

In addition, for safety software consider:

Principles of simplicity, decoupling, and isolation to eliminate hazards. Safety features should be separate from nonsafety modules minimizing the impact of failure of one module on another. Techniques, such as failure modes and effects analysis, fault-tree modeling, event-tree modeling, cause-consequence diagrams, hazard and operability analysis, and interface analysis.

System Structure

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Decompose the system into design entities or objects that will interact with and transform data to perform the required system objectives. Assign a unique name to each design entity, and group entities by type (e.g., class, object, procedure). Describe how each design entity satisfies system requirements. In user terminology, specify the inputs, outputs, and transformation rules for each design entity. Depict how design entities depend on one another.

Data Design and Control

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Using a data modeling technique identify specific data elements and logical data groupings that are stored and processed by the design entities in Section 5.1, "System Structure." Outline data dependencies, relationships, and integrity rules in a data dictionary. Specify the format and attributes of all data elements or data groupings. Contact the laboratory Enterprise Architect for assistance with data dictionary development and data management standards. See GDE-4, Data Management Guide, for additional guidance.

Develop a logical model of data flow through the system by depicting how design elements transform input data into outputs.

Human-Machine Interface Design

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Describe the user interface and the operating environment, including the menu hierarchy, data entry screens, display screens, online help, and system messages. Specify where in this environment the necessary inputs are made, and list the methods of data outputs (e.g., printer, screen, file). Note any design standards to be applied. If project human-machine interface design standards have been developed, discuss them in this section.

System Design Interface

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Specify how the product will interface with other systems. For each interface, describe the inputs and outputs for the interacting systems. Explain how data is formatted for transmission and validated upon arrival. Note the frequency of data exchange.

Security Structure

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Describe the software functionality supporting the security architecture of the system design. This would list features such as user privilege restrictions, logging of auditable events, and the encryption technology for securing data in storage or transmission.

Requirements Cross-Reference

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For each numbered system requirement, identify the section(s) of this document that specify how the functional design will meet the requirement. A separate requirements traceability matrix may be referenced for this section (see TEM-214).