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Systems ArchitecturesSystems Architectures Operational, InterfaceOperational, Interface

and Case Studiesand Case Studies

Course on

Systems Engineering

for

CASDE, Aero. Dept., IIT Bombay

ostgra uate tu ents o

21st October, 2013

Defence Institute of Advanced Technology, Pune


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Interface DesignInterface Design

Interface is a connection for hooking another system

(external interface) or for hooking one system component

to another (internal interface).Interface can contain both logical and physical elements

responsible for carrying items from one component (or


.Systems engineer is required to identify interfaces and

allocating items to the defined interfaces. Subsequently,

requirements for each interface are to be derived fromsystem level requirements.

In general,interfacesare the commonpoints of failure.


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Interface ArchitectureInterface Architecture

Development of interface architecture is undertaken inconjunction with the development of allocated physical

architecture,as discussed previously.

There are three broad options that comprise all the

architectures usedin interface design. These are;


Shared MemoryArchitecture

Network Architecture

Usually, standards help in ensuringthat aninterface willenable the connection of the two components. (e.g. RS

232, USB, RGBetc.)


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Interface ArchitectureInterface Architecture

Interfacearchitecture developmentprocess is as follows.



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Operational Architecture ConceptOperational Architecture Concept

Operational architectureprovides a completedescription

of system, including functional architecture, allocated

physical architecture, derived input/output, technology and

other trade-offs, qualification requirements &interfaces.

The development processfor the operational architecture


together.Given below are importantsteps in this regard.

Allocate functions/requirements to physicalsub-systems.

Define & analyzefunctional activation/control structure.Conduct performanceand risk analysis

Document architecture& sub-system specifications.


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Operational Architecture ConceptOperational Architecture Concept

Process todevelop operational architectureis as follows.



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Typical Operational ArchitectureTypical Operational Architecture

Architectureshowselements, theirrelations, includingdata flow.



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Given below aredetailed mission objectives.

CSCS 1: Permanent Moon Base1: Permanent Moon Base



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Functional Decompositionat System Level.




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Sub-system FunctionalDecomposition.




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Functional Requirements PhysicalAllocation.




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Physical Architecture.




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An air warfare control system manages the release of

weapons, threat D3 (degrade, disrupt, deny)and weapon

store levels. Following is the detailed need statementof

the abovemission.

Before an engagement, the engaging platform must be

CSCS 2: Typical Air Warfare Mission2: Typical Air Warfare Mission


.

When the platform is enabled, the weapon system is

started, if it is not already on, with the weapon launcher

disengaged.

When the trigger on the platform is depressed, launcher

is engaged and theweapons are released.


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There is an interlock that prevents the weapons from

being released unless athreat has been detected.

Once no threats are detected, the engagement is deemedcompleted and the platform is de-authorized from

further weapon release. Further depressionof the release

CSCS 2:Typical Air Warfare Mission2:Typical Air Warfare Mission


switchmust not releaseany more weapons.Lastly, after a short standby period, the platforms

weaponsystem is to be turned off, unless re-authorized.

In addition, ametering device sendsa pulse to the system,

every time aweapon is released, enabling cost estimates.


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With regard to D3 assessment, these are stored until the

status of threat is known.

It is anticipated that sometimes, the threats escapewithout damage and air warfare officer is required to

annotate D3 assessment, with any available information.

CSCS 2: Typical Air Warfare Mission2: Typical Air Warfare Mission


At the end of each day, D3 assessmentsare to be archivedand may beused for ad hoc enquiriesinto engagements.

At present, two weapon typesare to be released from five

platforms in the battle-space. Each platform takes one ofthe two weapon stores. The weapon store levels must not

be allowed to fall below 4%of the store capacity.


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Given below isthe air warfare system synthesizedfor thefunctionality stated inprevious slides.

CSCS 2: Typical Air Warfare System2: Typical Air Warfare System


Further, abattle group engages the targetswithin a battle

space under control ofan AW officer.Battle group consists of number of platforms, each with

sensors (S),processors (P)and weapons (W).


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Thearchitecting process is basedon analogy.

CSCS 2: Typical Air Warfare Architecting2: Typical Air Warfare Architecting



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System Design Guidelines& Requirements.

CSCS 3: University Space Mission3: University Space Mission



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Functional Decomposition.




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Physical Architecture.




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Given below is functional decomposition& allocation foran aircraft mission withgreater clarityup to third level.

CSCS 4: Typical Aircraft Mission Architecting4: Typical Aircraft Mission Architecting



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Given below is the corresponding physical architecturethat will achieve thefunctional requirements.

CSCS 4: Typical Aircraft Mission Architecting4: Typical Aircraft Mission Architecting



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Good Architecture AttributesGood Architecture Attributes

Meets the needsof the stakeholders (especially the users)

to their satisfaction.

Does not violateestablished principles of architecting.

Takes into account relevant -lities by allowing formaintenance, evolution etc., as the customer requires.

Are also elegant (intellectually clean of unnecessary


complexities or 'exceptions').Can directa builder to cost-effective structures that can be

completed within a reasonable time frame.

Are conceptually pleasingto stakeholders (esp. user).Provide some special advantage (such as a competitive

advantage) or utility to the customer.


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How to get Good Architecture?How to get Good Architecture?

Plan for Essential Complexity; avoid GratuitousComplexity.

Spendenough time on designing interfaces.

Iterate on architecture until a satisfactory solution is

reached.


.

Providerobustness to anticipated risks.

Go bythe customer's opinion in case of a difference.

Thinkholistically to arrive at good architecture.Ensure modularity for easier testing, induction of newer

ideas.


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How to get Good Architecture?How to get Good Architecture?

Understanddecompositions/ interactions in system parts .

Adhere to basic governing laws of the usage context in

which the system operates; elegance comes later

Preventambiguity from creeping into the system throughdifficulties in communication.

Identifysources for user needs appropriately, and obtain


user needs from them.Verifythe implementability of an idea stated simply.

Include uncertainty of information in the architecture

design process.Be aware of possible future things happening, future

technologies, future values...


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SummarySummary

Functional thinkinghelps to improveupon the system astechnological advancescan be included inarchitecture.

If a system is to be evolved from scratch, logical procedure

isbased on elementsthat appear tocontribute to system.Sometimes, architecting is driven by products that

s nthesize to form desired s stem, articularl when a


newtechnology is to be inductedfor samefunctionality.operational architecturesprovide additional insight into

the design solution, including behavioral aspects of the

system.Interface architectureis evolved using same philosophy

of functional thinkingand physical translation.


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ReferencesReferences

NASA Systems Engineering Handbook

INCOSE Systems Engineering Handbook

A Primer for Model Based Systems Engineering, VITECH

The Engineering Design of Systems, Dennis M. Buede

Design Methodologies for Space Transportation Systems, Walter E. Hammond,

AIAA Education Series

Space Transportation : A Systems Approach to Analysis & Design., Walter


, .

Methodology of Aircraft System Architecture Sizing, 26th International Congress ofAeronautical Sciences

Civil Aircraft Advanced Avionics Architectures, NAL

Conflicting Heuristics for Low-cost Launch Vehicles Architectures, Karl Gallagher

Architecture and Principles of Systems Engineering, CE Dickerson & DN Mavris.

Engineering Design, Dieter, Schmidt, 4th Ed.

Systems Engineering and Analysis, Blanchard, Fabrycky.

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