N2 Chart 8 MB

 

One of the increasingly significant problems facing the system designers and master planners of today is the timely and accurate definition of system element interfaces and task or activity interrelationships.

The classical approach to requirements and/or activity definition and allocation consists of the subdivision of large functions into multiple, understandable, discipline-oriented modules or blocks. Each of these blocks is then defined or specified in terms of its inputs, outputs and transfer functions. The emphasis, unfortunately, is usually placed on transfer functions, while the inputs and outputs (interfaces) are all but ignored. Transfer function definitions are more readily understood and communicated than interface definitions since these functions are quantifiable, structured, close to the implementation design, and can be easily related to past experience. A structured technique or discipline must therefore be acquired by the effective system designer and master planner, which places equal weight on all of the definition and allocation parameters. Interfaces and activity relationships must be dealt with in a top-down, hierarchical manner which is as structured and timely as today’s transfer function definition process. The implementation of an effective interface definition methodology has become essential due to the increasing relationship complexity of today’s tasks, organizations and systems.

This book describes the N² Chart, which is an implementation tool and methodology for the tabulation, definition, analysis and description of functional and physical interactions and interfaces. The tool presented is not limited to any particular field, discipline, market area, or system type. The N² Chart is simple and easy to understand, structured and methodical, top-down in nature, communicative of the design, and forces a uniform level of design consistency. The N² Chart is an effective tool for the integration of all of the people, products, and paper that make up any given system.

An initial N² Chart definition is provided, together with discussions relating to its various usages, formats and applications. Applications covered include interface tabulation, definition, design and analysis activities. Other non-obvious applications are additionally discussed which are concerned with design description, operational procedure analysis and schedule analysis activities. Examples are presented of actual N² Chart implementations on numerous TRW studies and proposal activities. Two examples are presented in detail which illustrate the applications of the N² Chart in interface problem solving and in top-down system design definition.

Table of Contents –

 

1. INTRODUCTION 

 

2. DEFINITION

            2.1 General

            2.2 Formats

            2.3 The Time-Sequenced N² Chart

            2.4 The Loop N² Chart

            2.5 What the N² Chart Shows

 

3. APPLICATIONS

            3.1 Introduction

            3.2 Interface Tabulation

            3.3 Interface Definition

            3.4 Interface Design and Analysis

            3.5 Design Description

            3.6 Operations Analysis

            3.7 Schedule and Activity Analysis

 

4. A PROBLEM SOLUTION EXAMPLE     

            4.1 Introduction to the Problem

            4.2 System Function Definition

            4.3 Flow Analysis and N² Chart Completion    

            4.4 System Architecture Comparison

            4.5 The Adopted New System Architecture     

            4.6 Original Interface Problem Solution

            4.7 Application Results

 

5. A SYSTEM DESIGN EXAMPLE

            5.1 Introduction to the Problem

            5.2 Level I Description

            5.3 Level II Description

            5.4 Level III Design     

            5.5 Level IV Design

            5.6 Application Results

6. CONCLUSION