Environmental Engineering Reference
In-Depth Information
Cassini,.and.New.Horizons.missions..In.addition,.RTGs.were.used.to.power.
the.two.Viking.landers.and.for.the.scientiic.experiments.left.on.the.Moon.
by.the.crews.of.Apollo.12.through.17..RTGs.were.also.used.for.the.Nimbus,.
Transit,.and.LES.satellites.
A. photovoltaic. battery. is. a. solid-state. device. that. converts. the. energy. of.
sunlight. directly. into. electricity. by. the. photovoltaic. effect. (Tsokos. 2008)..
Assemblies. of. cells. are. used. to. make. solar. modules. and. solar. panels. that.
produce. solar. energy.. The. photovoltaic. effect. was. irst. recognized. in. 1839.
by.French.physicist.A..E..Becquerel..It.was.not.until.1883,.however,.that.the.
irst.photovoltaic.cell.was.built.by.C..Fritts,.who.coated.the.semiconductor.
selenium.with.an.extremely.thin.layer.of.gold.to.form.junctions..The.device.
was.only.1%.eficient..In.1888,.Russian.physicist.Aleksandr.Stoletov.built.the.
irst. photoelectric. cell.. Russell. Ohl. patented. the. modern. junction. semicon-
ductor.solar.cell.in.1946,.which.was.discovered.as.he.worked.on.the.series.of.
advances.that.would.lead.to.the.transistor.
Spacecraft. can. be. powered. by. energy. stored. in. a. battery. or. fuel. cell.
and. released. as. the. craft. travels,. or. it. can. be. generated. as. the. journey.
progresses.(Patel.2004)..There.are.several.ways.to.store.and.make.energy..
The. batteries. store. energy. made. on. Earth. and. release. it. as. electricity..
Additionally,. the. solar. panels. convert. light. from. the. Sun. into. electricity..
RTGs. utilize. radioactive. materials,. encased. in. a. sealed. shell. to. generate.
heat. as. they. decay. into. nonradioactive. materials.. Finally,. fuel. cells. are.
somewhat. like. batteries,. storing. power. in. the. form. of. separated. oxygen.
and.hydrogen..A.thin.membrane.between.the.two.elements.harnesses.the.
energy.released.when.the.oxygen.and.hydrogen.combine.to.form.water.
System.dynamics.(SD).is.used.to.quantify.the.dynamic.scenario.for.a.non-
linear.algorithm.that.can.be.applied.in.the.nuclear.industry..Dr..Jay.Forrester.
at. Massachusetts. Institute. of. Technology. (MIT). created. SD. to. evaluate. the.
nonlinear.characteristics.of.social.and.economical.systems..SD.can.test.the.
dynamic.scenarios.of.complex.systems..SD.has.been.used.to.quantify.orga-
nizations. over. time. (Forrester. 1961,. 1968,. 1969,. 1971).. In. addition,. there. are.
some.papers. related. to.decision. making. using. SD.(Eberlein. 1989;. Forrester.
1975;.Kampmann.1996;.Liehr.et.al..2001;.Mojtahedzadeh.1997;.Schmidt.and.
Gary.2002).
A.study.by.Nathan.et.al..(cited.in.Minami.and.Madnick.2009).discussed.the.
results.of.several.simulations;.these.suggested.that.high-level.decisions.that.
balance. mission. rate. and. operations. tempo. with. troop. availability,. careful.
management.of.the.work-rest.cycle.for.deployed.troops,.and.improvement.of.
the.processes.for.evaluating.the.lessons.learned.from.accidents.would.lead.to.
a.reduction.in.combat.vehicle.accidents..In.addition,.a.model,.extracted.from.
a.larger.study,.is.used.to.evaluate.the.effect.of.road.conditions.on.accident.
development.(Sheldon.2006).
Section.5.2.explains.the.economic.aspect.of.the.study..The.calculation.for.
the.safety.aspect.is.shown.in.Section.5.3..Section.5.4.describes.results.of.the.
study,.and.some.conclusions.are.discussed.in.Section.5.5.
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