Environmental Engineering Reference
In-Depth Information
5.3 SafetyAspect
In.space.travel,.the.SD.method.is.used.for.simulations.due.to.its.capabilities.
of.analytic.estimation.and.quantiication..The.matter.incorporated.with.the.
technological.implication.has.been.investigated.by.SD.for.a.variety.of.factors..
In. addition,. the. tools. show. the. dynamic. decision-making. abilities. in. com-
plex.matters..The.Vensim.package.used.for.the.simulation.was.developed.in.
Ventana.Systems,.Inc.
SD. is. described. as. a. powerful. computer. simulation. modeling. technique.
for. understanding,. framing,. and. discussing. complex. issues. and. problems.
(Radzicki.and.Taylor.1997)..SD.can.help.managers.improve.their.understand-
ing. of. industrial. processes,. and. is. currently. used. in. many. kinds. of. policy.
analysis.and.design..SD.shows.the.basic.building.blocks.that.can.construct.
models.of.how.and.why.complex.real-world.systems.behave.the.way.they.do.
during.a.speciied.time.period..The.object.is.to.leverage.this.added.under-
standing.to.design.and.implement.more.effective.policies..The.most.impor-
tant.aspect.of.SD.modeling.involves.the.dynamic.behavior.of.systems,.where.
the. operator. tries. to. identify. the. patterns. of. behavior. exhibited. by. certain.
system.variables,.and.then.builds.a.model.with.the.characteristics.of.those.
patterns.. The. model. can. be. used. as. a. laboratory. for. testing. policies. aimed.
at. altering. a. system's. behavior. in. desired. ways.. The. SD. model. uses. single.
and.double.arrow.lines.to.indicate.event.and.time.lows..Understanding.the.
dynamic.behavior.of.a.system.using.SD.involves.its.key.physical.and.infor-
mation.lows,.stocks,.and.feedback.structures..Some.characteristics.of.SD.are.
as.follows:
Single.arrow.line:.Indicates.the.low.of.the.event.and.shows.the.sequence.
of.the.scenarios.as.well.as.their.dynamic.behavior..The.direction.of.line.gives.
the.event.low.and.event.feedback.
Double.arrow.line:.There.is.the.principle.of.accumulation.which.is.to.be.
raised.by.dynamic.behavior.in.the.SD.modeling..This.means.that.all.kinds.of.
dynamic.behaviors.can.be.happening.when.lows.accumulate.in.stocks..This.
is. seen. in. FigureĀ  5.4. as. EXAMPLE. for. accumulation. and. INPUT/OUTPUT.
for.lows..This.is.like.a.bathtub.where.the.low.can.be.thought.of.a.faucet.and.
pipe.assembly.that.ills.or.drains.the.stock..It.should.be.considered.as.the.sim-
plest.dynamic.system.in.the.stock-low.structure..In.SD,.both.informational.
Example
Output
Input
+
FIGURE 5.4
Stock.low.and.feedback.
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