Safety Assessment Study in Nanoscopic Circumstances for an Accidental Cooling Loop Failure (ACLF) in a Lunar Nuclear Power Reactor (LNPR) - Atomic Nanoscale Technology in the Nuclear Industry - page 39

and.feedback.structures.for.SD..Several.characteristics.of.SD.are.explained.
in.the.following.text.

•. Nonlinearity: .A.large.part.of.SD.modeling.process.involves.the.appli-
cation.of.common.sense.to.dynamic.problems..Such.behaviors.usu-
ally.indicate.a.nonlinearity.of.the.events..This.is.seen.as.single-.and.
double-arrow.lines.in.the.modeling..The.arrow.line.shows.the.event.
low.without.any.restriction.
•. Stock low: . The. principle. of. accumulation. is. affected. by. dynamic.
behavior,. which. means. that. all. kinds. of. dynamic. behaviors. could.
happen. when. lows. accumulate. in. stocks.. Both. informational. and.
noninformational. objects. can. move. through. lows. and. accumula-
tions.in.stocks.
•. Feedback: . The. effect. of. feedback. loops. is. shown. by. the. stocks. and.
lows. in. real-world. systems.. The. feedback. loops. are. often. joined.
together. by. nonlinear. couplings. where. any. object. can. cause. coun-
terintuitive.behavior.
•. Time Paths: . The. dynamic. behavior. of. systems. is. quantiied,. where.
the. operator. tries. to. identify. the. patterns. of. behavior. exhibited. by.
certain.system.variables,.and.then.builds.a.model.with.the.charac-
teristics.of.those.patterns.

There. are. special. expressions. for. these. characteristics. in. SD. modeling..
Especially.in.the.Vensim.code,.technical.methods.are.shown.as.single-.and.
double-arrow.lines.as.follows:

•. Single-arrow. line:. This. line. shows. the. low. of. the. event.. It. is. the.
sequence. of. the. scenarios. as. well. as. the. dynamic. behavior.. So,. the.
direction.of.the.line.gives.the.event.low.and.event.feedback.
•. Double-arrow. line:. The. dynamic. behavior. is. increased. in. SD.
modeling.for.the.principle.of.accumulation..All.kinds.of.dynamic.
behaviors.can.happen.when.lows.accumulate.in.stocks,.which.are.
seen. in. Figure 4.7. as. EXAMPLE. for. accumulation. and. INPUT−
OUTPUT. for. lows.. This. is. like. a. bathtub. where. a. low. can. be.
thought. of. as. a. faucet. and. pipe. assembly. that. ills. or. drains. the.

Example

Output

Input

+

FIGURE 4.7
Stock.low.and.feedback.