Functional Flow Diagrams Research Articles

Model Based Functional Safety – How Functional Is It?

As the engineering world embraces Model Based System Engineering (MBSE), the system safety discipline should also enfold and support MBSE methodology and approaches. The need for Model Based Functional safety, as part of the established system safety and software safety process, is becoming apparent due to existing and developing system design complexity. This paper is intended to show how valuable Model Based Functional Safety approaches can be when evaluating safety signification functions of complex software-intensive integrated systems. Using models can improve the accuracy during the Functional Hazard Analysis (FHA) and can help validate Fault Tree Analyses (FTA) and subsequent system safety analysis (SSA) process and results because the model focuses on the architecture, the physical system, the computer system, as well as the applicable software/middleware/Programmable Logic Devices (PLDs). Model Based Functional Safety may utilize use cases, structural architecture models, activity diagrams, sequence diagrams, functional flow diagrams, and state/mode models to depict safety attributes and to influence explicit safety requirements. SysML may be used to depict critical functions, functional threads, safety features, and expected behavior. Such augmented models (safety models) can also be used to analyze potential off nominal failure conditions and system behavior for various scenarios when conducting FHAs and subsequently detailed system and software safety analyses. This paper will provide an example of the MBSE framework and concepts for tool use in the functional safety analysis and the utilization of attributed models and artifacts to supplement system safety documentation.

Floor Heating of Piglets Using a Thermoelectric Heat Pump

A functional and process flow diagram of an energy-saving floor heating panel using a thermoelectric assembly operating in a heat pump mode has been developed. The technique and calculation of the main heat-and-power parameters of this installation are presented. Studies of a working prototype of a floor heating panel, which have shown the high energy efficiency of the installation being developed, have been performed. It is shown that energy saving is about 15% in comparison with the serially used equipment for local heating of young animals.

Aspect‐Oriented Architecting Using Architecture Frameworks

AbstractIn the early days of systems engineering, we had a few tried and true methods for depicting the structure and behavior of a system, such as functional flow diagrams, control flow diagrams, state transition diagrams, schematic block diagrams, and system breakdown structure. Nowadays we have a wider variety of choices when it comes to the creation of architecture views. The Unified Architecture Framework, for example, defines 71 possible architecture views that can be created. An easy and intuitive way to navigate the many available offerings was needed. Hence, most architecture frameworks have adopted a “grid” approach to help organize the various views. One of the key dimensions of this organizing approach is the use of architecture aspects. This paper will examine the various frameworks to determine how they organize their views and how they address the different aspects and perspectives of the architecture being described. These concepts were used as the basis for an aspect‐oriented architecting approach reflected in the recently revised version of the ISO 42010 standard on architecture description.

Разработка и исследование осушителя и подогревателя воздуха на базе элементов Пельтье

A functional flow diagram of an energy-saving dehumidifier and an air heater based on Peltier elements has been developed. A method for calculating the heat-power and design parameters of a thermoelectric assembly is presented. Physical modeling of the process of dehumidification and heating of air in a thermoelectric installation has been carried out. The results of tests of a working model of the thermoelectric dehumidifier and air heater are presented. Rational operating modes of the installation have been substantiated, and its energy efficiency in the heat pump mode has been shown.

Thermoconomic analysis of cogeneration installation (cgam) based on theory of the exergetic cost

Modern cogeneration systems are complex energy-technology complexes with a high degree of energy recovery. Pre-design analysis of these systems must take into account both the economic and thermodynamic components of the process of energy conversion. The most scientifically grounded basis for the development of recommendations for the design of aggregates of the cogeneration system is the modern method of thermoeconomic analysis. On the basis of the theory of exergetic cost, a thermoelectric model of a cogeneration unit is constructed, which takes into account the nonequivalence of exergy losses, which is related to the structural-topological features of the technological scheme. The thermoeconomic model has a hierarchical structure, which is a thermodynamic model, which is necessary for the determination of exergy flows, as well as an exergo-topological model that establishes, by means of flow graphs, the interconnections between exergetic flows in the installation. For visualization of the thermoelectric model, a functional exegetic flow diagram of a cogeneration unit is proposed, which helps to perform the separation of flows for a qualitative sign "fuel" - "product" of the element. In order to further coherent assessment of the exergetic and economic indicators of the system to the general thermoelectric model, the functions of the capital cost of the elements can be involved.On the basis of the numerical implementation of the thermoelectric model in the technological scheme of the installation areas are identified that have an excessive specific consumption of exergy, anomalies and dysfunctions for each element of the scheme. With the involvement of methods of the theory of experiment planning, regression models of the exergy efficiency of the installation were constructed depending on the determining factors, the factor analysis was performed and the interrelated influence of them on the exergy efficiency of the installation was determined.

A model based system engineering approach to design Avionics systems: Present and Future prospect

AbstractSystem complexity in Defense and Aerospace Industry is increasing day by day. Conventional System Engineering is document centric. Text based documents describe system specification, store the records, describe concept of operations and interfaces etc. There are numerous design challenges faced by system engineer while working on text based requirements. Programs are prone to errors during Requirements Definition phase. Also as designs grow and change, maintaining documents becomes an uphill task. Model based approach in System Engineering has ability to detect defect at much more early stage than conventional text based method. Model Based Systems Engineering (MBSE) uses various block diagrams, state machines, mathematical equations, functional flow diagrams, object‐oriented models which help to understand the Data flow between various subsystems. This paper explains the advantages of model based system engineering over conventional text based approach, a seamless transition strategy from Document‐based to model‐based approach and its various applications in defense and Aerospace domain with future prospect.

Technology for Making Leakproof Structures Based on Carbon–Carbon Composites of the Uglekon Type

Processes for making a new class of hermetic carbon–carbon composites that are stable under extreme service conditions – high temperatures and aggressive metallic melts and chemicals – have been researched and developed. Researchers have developed a functional flow diagram for making such materials and have determined its parameters in each technological conversion. The physico-mechanical properties of two types of carbon load-bearing substrates are compared and the preferred type of substrate is chosen. A study is made of the main kinetic parameters of the saturation of the substrate and the slip sublayer with pyrocarbon, which results in the formation of a hermetizing pyrocarbon coating on the sublayer.

2.1.2 The Middle‐out Systems Engineering for Gray‐Box Item and Case Study of Automotive Lock Housing Assembly

AbstractLock housing assembly is a vehicle component which is designed and manufactured by a 2nd tier supplier of a car maker. This paper showed a middle‐out systems engineering approach for a gray box item development. In the case of gray box item development, the communication between a car maker and suppliers is a key success factor to overcome unclear and unbalanced design responsibility from the viewpoint of supplier. To show the middle‐out systems engineering process, this paper addressed the development of a magnesium lock housing assembly. This project used some methodologies such as Quality Function Deployment (hereafter QFD) and functional flow diagram etc. to enhance communication capabilities. The customer requirements were developed with QFD while functional flow diagram was used to derive quality control parameters.

Support Activity Flow Based Forecast Model for the Quantity of the Aircraft’s Support Equipments during Design and Development Phase

In order to resolve the problems encountered in the process of forecasting the quantity of equipments demanded by aircraft’s support system during the design and development phase, including the difficulty to collect the input data of the existing forecast models and their imprecise and unauthentic output results, a model of was established to forecast the number of support equipments based on support activity flow described by functional flow diagrams. Firstly, the aircraft’s typical mission was analyzed and the quantity of operation and maintenance support activities happened in the duration of the mission was calculated on the basis of the typical mission’s data and aircraft’s reliability data. Secondly, the working hours and maximum number of the support equipments demanded by the support activities in the bottom of the functional flow diagrams was calculated and analyzed. Thirdly, an approach to sum the working hours and maximum quantity of the support equipments demanded by the support activities with logic relations in the same level of the functional flow diagrams was presented and with which the working hours and maximum number of support equipments demanded by the top-level support activity was achieved. Fourthly, the quantity of support equipments to be allocated in the support sites was calculated. At last, the proposed model was demonstrated via a practical case of aircraft, which proved that the model is corrective and effective.

The Effect of Functional Flow Diagrams on Apprentice Aircraft Mechanics' Technical System Understanding

Cognitive theory suggests that a key to expert performance lies in the internal organization of the expert's knowledge. The authors contend that the type of technical illustration used during instruction influences knowledge organization and greatly impacts students' understanding of the content. This paper describes an experimental study that tested the impact of one type of conceptual illustration on students' understanding of the structure, function, and behavior of complex technical systems. The results show that supplementing traditional technical instruction with functional flow diagrams can improve overall system understanding. The functional flow diagrams were also found to be an effective instructional aid for enhancing students' conceptual understanding of the causal behavior of systems. In addition, the use of the functional flow diagram was found to significantly improve the subjects' ability to construct conceptual models that were similar to those of an expert. The implications of using conceptual diagrams for technical instruction are discussed and recommendations for future research in this area are provided.

UML 2 activity model support for systems engineering functional flow diagrams

AbstractThis article compares Activity models of the Unified Modeling Language, version 2 (UML 2) [OMG (Object Management Group), UML 2.0 superstructure specification, August 2003, http://www.omg.org/cgi‐bin/doc?ptc/03‐08‐02], to a widely‐used systems engineering (SE) flow diagram, the Enhanced Functional Flow Block Diagram (EFFBD) [J. Long, Relationships between common graphical representations in system engineering, ViTech Corporation, 2002], and to the requirements for functional flow modeling in a systems engineering extension for UML (UML‐SE) [OMG Systems Engineering Domain Special Interest Group (SE‐DSIG), UML for systems engineering RFP, March 2003a, http://www.omg.org/cgi‐bin/doc?ad/03‐03‐41]. Issues are identified in applying UML 2 Activities to EFFBD and to satisfying UML‐SE functional flow requirements. Solutions are suggested to these issues that can be used to translate between the languages and to develop standards such as revisions to UML 2 or extensions in UML‐SE. *© 2003 Wiley Periodicals, Inc. Syst Eng 6, 249–265, 2003

Modelling Combat System Manning & Manpower Reduction

AbstractNAVSEA 03K41 is responsible for generating Combat System Battle Management Organizations (BMO) and Functional Flow Diagrams (FFD). Several years ago, NAVSEA provided the resources to conduct a functional analysis that would support the development and validation of the BMOs and FFDs. The major obstacle in performing the analysis was obtaining a consensus on how the functional hierarchy was to be structured. The non‐optimum organization of the hierarchy was selected; as a result, the functions were difficult to define, find, use, and validate. Recognizing the shortcomings of this effort, research was conducted to evaluate state‐of‐the‐art structured modelling techniques, concepts, and methodologies. Two modelling concepts by James Martin were found to be applicable for the combat system functional analysis: Enterprise Modelling Concept and Functional Decomposition Modelling Concept. The Structure Modelling definitions of Whitten, Bently, and Barlow provided the guidelines for using the Martin concepts. During the ensuing BMO and FFD development efforts, a Ship's Combat System (SCS) Modelling concept evolved and a SCS Model was developed. This paper addresses how the modelling concepts and tools are used in the BMO and FFD development and validation process. Data from the SCS Model provides the basis for defining combat system requirements (e.g., software, data display, database, networking, etc.).

Modelling Combat System Manning and Manpower Reduction

ABSTRACT NAVSEA 03K41 is responsible for generating Combat System Battle Management Organizations (BMO) and Functional Flow Diagrams (FFD). Several years ago, NAVSEA provided the resources to conduct a functional analysis that would support the development and validation of the BMOs and FFDs. The major obstacle in performing the analysis was obtaining a consensus on how the functional hierarchy was to be structured. The non‐optimum organization of the hierarchy was selected; as a result, the functions were difficult to define, find, use, and validate. Recognizing the shortcomings of this effort, research was conducted to evaluate state‐of‐the‐art structured modelling techniques, concepts, and methodologies. Two modelling concepts by James Martin were found to be applicable for the combat system functional analysis: Enterprise Modelling Concept and Functional Decomposition Modelling Concept. The Structure Modelling definitions of Whitten, Bently, and Barlow provided the guidelines for using the Martin concepts. During the ensuing BMO and FFD development efforts, a Ship's Combat System (SCS) Modelling concept evolved and a SCS Model was developed. This paper addresses how the modelling concepts and tools are used in the BMO and FFD development and validation process. Data from the SCS Model provides the basis for defining combat system requirements (e.g., software, data display, database, networking, etc.).

Designing an Electron Microscopy Facility: Step by Step Procedure

Abstract Designing a microscopy facility can be completed in a step by step approach, whether it be a completely new facility or an existing one moving into expanded quarters. The procedure is independent of size. There are several major factors that must be taken into consideration. Check lists can be compiled by the microscopist. One should easily be able to start at any point along the way. The time and effort initially put into the design will pay for itself many times over in convenience and efficiency of the resulting laboratory. Prior to drawing the actual design of the microscopy facility but critical to the design specifics, it is necessary to compile the following information: considerations for determining the size of the facility; general EM lab requirements which affect site determination; activity functional flow diagram; EM room requirements; a list of all the equipment to be placed in the EM facility and exact specifications for each; design features not associated with specific equipment; activities requiring space that are not specific to the equipment; general building requirements not specifically related to microscopy operations; and ergonomic and psychological factors.

IN DEFENSE OF THE TRADITIONAL SYSTEM REQUIREMENTS ANALYSIS PROCESS

ABSTRACTSome new requirements tools and techniques carry with them the suggestion that the traditional system requirements analysis (SRA) process is somehow deficient and passé. This paper re‐visits that process, expands its structured decomposition techniques to include alternatives to functional flow diagramming, augments it with structured interface, environmental, and specialty engineering requirements analysis and adapts it to the Integrated Product Development (IPD) approach.In the traditional SRA approach, it was never clearly explained how it began, leaving many to conclude that there was a chicken‐and‐egg problem hiding in there somewhere. It also was never clear where it ended (decompose as required). Some have concluded that the process has neither beginning nor end, only a very expensive middle producing paper of great mass but questionable utility. The traditional process also focused principally on performance requirements. It provided an effective demand driver for only one of three kinds of constraints and had little to offer for programmatic requirements analysis.All of these shortcomings are disposed of in this paper revealing a comprehensive, flexible, and robust approach to project‐wide requirements analysis linked to recent advances like quality function deployment (QFD), IPD concepts, and the U.S. Air Force integrated planning initiative. The process is described more fully in a new book about an old process titled System Requirements Analysis (Grady 1993).

Color Doppler evaluation of arterial stenoses and occlusions involving the neck and thoracic inlet.

Color Doppler flow imaging is a new technique providing simultaneous display of a gray-scale tissue and a color-flow vascular image. We demonstrate its ability to predict accurately occlusions of numerous vessels, including the internal carotid, external carotid, common carotid, subclavian and innominate arteries. Alterations in flow direction and changes in spectral wave form provide useful clues to the presence of these occlusions. The cases are correlated with angiographic findings and functional flow diagrams of the hemodynamic changes involved.

Use of Structured Development Techniques to Specify the User-System Interface

The Human Factors Engineering products from the systems requirements phase of system development were transformed into techniques consistent with structured software development techniques. These techniques supported definition of the mission functions with the context diagram, the task list was compatible with the event list, and high level functional flow diagrams are consistent with the structured data flow diagrams. In addition, the sequenced task analysis procedures used provided a structured diagraming methodology in state transition diagrams. This technique provided a method for defining MMI requirements in software engineering terminology.

Simulation Study of an Aircraft's Environmental Control System Dynamic Response

SIMULATION was made of the environmental control system (ECS) of a high-performance aircraft. The ECS provides temperature control for the cockpit and avionics equipment bays, throughout the flight performance envelope of the aircraft. This is achieved by bleeding hot air from the engine, cooling part of it, and mixing the hot and cold flows. The sensors, controller, and valves of the system were modeled, as well as the heat exchangers and expansion turbine. The simulation was programed in CSMP, on an IBM 370/165 computer and operated over an array of conditions representative of the whole operational envelope of the ECS. Dynamic response was compared to specification s and sensitivity of performance to system parameters was measured. A partial evaluation of the simulation was achieved by using some available laboratory test results and comparing these with simulation results from the same conditions. The rationale, models, program, and results are presented in this paper. Content The environmental control system (ECS) of a highperformance aircraft is required to perform complex tasks. Consequently, it is complex in design. The ECS must supply proper temperature air to the cabin and to the avionics equipment, within the entire performance envelope of the aircraft and within the entire scale of external conditions of temperature and pressure. There are specifications on the dynamic behavior which require the system to stabilize within seconds and to not exceed specific inlet temperatures to the cabin and equipment which would be harmful to the pilot and to the avionics. Proper flow levels must be maintained and it is necessary that no severe pressure changes reach the cockpit, which would be uncomfortable to the pilot. To verify the design of the ECS for a high-performance aircraft, a simulation was made which portrayed the dynamic performance of the system. It was intended to study stability, study sensititivity, identify possible problem areas in the design, and serve as a tool to evaluate the dynamic effects of any future design changes. A discussion of the system follows. System Description. The ECS provides temperature control for the cockpit and avionics equipment bays, throughout the flight performance envelope of the aircraft. This is achieved by bleeding hot air from the engine, cooling part of it, and mixing the hot and cold flows. Transient changes into the ECS occur when the pilot alters the engine throttle setting and/or when altitude changes occur. A functional flow diagram of the ECS system is shown in Fig. 1. The rate of flow of bleed air from the engine is

System Data through Functional Techniques

A unique functional concept in the field of system display which allows rapid and effective communication of design information is introduced. This is to be accomplished through the presentation and explanation of a Single Line Functional Flow Diagram technique. The format is arranged along the same left-to-right flow lines traditionally associated with reading text. The component grouping into recognizable sub-groups follows the same principal as speed sight reading, thus providing the reader with schematics which can be rapidly and accurately read, rather than a puzzle which must be solved. The principle result is an improved engineering data approach which yields multi-purpose functional data suitable for direct application in many engineering and technical support areas without expensive rework.