SY DE 142
Final Exam Review
Roshanak Moradi
Munira Jessa
August 12th , 2004
Introduction to Human Systems Engineering
Waterloo, Ontario, Canada
Outline
 Exam Details
 Case Studies
 Course Material
Exam Details
 Friday August 13, 2004 from 9:00 to 12:00
 E2-1303 A,B, and E (NOT the regular classroom)
 Aids Allowed:
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Set Phasers on Stun,
Wickens,
basic calculator (not programmable)
 Format:
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Short answer questions (from case studies)
Crossword puzzle
Anthropometric/Biomechanical questions
Case study (same as practice final)
Some pointers on exam
preparation
 Final From Last year/s - get a sense of how things went
 No Multiple Choice this year, you got a puzzle
“ we find students know the material in a general sense, but make errors in
terms of expressing things clearly, hitting all the points, thinking hard
about the question and really taking the right approach etc. “
 prepare by working through the web assignments.
 Try the case study from 3mile island and look at solutions.
 Critique your *solution presentation* and develop a perspective on exam
writing
 Try to communicate with marker, be thoughtful and thorough.
 Watch the marks allowed on all questions. They are a strong indicator
for the number of points expected.
Case Studies
 Business in Bhopal
 Silent Warning
 In Search of the Lost Cord
 An Act of God
 The Wizards of Wall Street
More Case Studies…
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Rental Car
Set Phasers on Stun
Zzzzs in Zeebrugge
The Peppermint Twist
Never Cry Wolf
Tigershark!
Return from Salyut
Genie in a Bottle
st
1
 Accident Analysis and
Fault Trees
 Mappings and
Affordances
 Gulfs of Execution and
Evaluation
 Human Action Cycle
 Information Processing
 Human Decision
Making
 Human Error - Mistakes
half
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Human Error- slips
Human machine model
Displays
Control
Human-Computer
Interaction
 Usability Testing
 Automation
nd
2
 Usability Testing
 Stress and mental workload
 Circadian Rhythms/Shift
work
 Vision
 Lighting & Visual Search
 Noise and Vibration
 Indoor Climate
half
 Anthropometry
 Work Physiology
 Biomechanics
 Social Factors, Teamwork
 Transportation
 Personnel / Training
Some notes on FTA
 Faulty policies are definitely factors in accidents. A fault tree
analysis is nothing more than a chain of events though.
Things which are overall factors are not included e.g."
worker was tired/stressed/not trained". These are not events.
 The FTA looks at events with the object. If the user initiates
an event then it can go in the analysis. The description
though must be event based e.g. "machine in high radiation
mode" and "activation button pressed."
Note that this describes the state and the events of the object.
Usability and user testing
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Usability Approaches (4)
 Cognitive walkthrough
 Heuristic evaluation (Neilson’s usability principals)
 Performance measurement
 Field study
Tasks
 Usability measures (satisfaction, learnability, errors)
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Design for user
 User health and safety:
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Circadian Rhythms and Shiftwork
Vision
 Health related environmental issues:
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Lighting
Noise and Vibration
Indoor climate
Design for Groups
Group characteristics
Groupthink
Social Factors, Teamwork and
Communication
Stress and Mental Workload
 Yerkes-Dodson Law
 Measurement:
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Primary Task
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Secondary Task
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Add a 2nd task and measure it
Physiological
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 Optimum Level of Arousal
Speed, Accuracy
Heart Rate, Blood Pressure
Subjective
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Questionnaires
Visual Search
 Identification of targets in a field of non-targets
(distractors)
 Time (1 target) = (number of items x inspection
time)/2
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Average time, based on probability of finding a target
Key points: more items=more time
Only applies to very itemized searches (e.g.phone books)
Vision & Lighting & Indoor
Climate
 Visual system , Visual Fatigue
 Ergonomics of visual tasks
 Intensity measurement with their units.
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(Luminous Flux from source), Illumination on surface, Luminance
from surface)
 Reflectance = Luminance (FL)/Illuminance (FC)
 Types of lighting in accordance to workspace (notes)
 Climate and air quality rules and guidelines (see notes)
Anthropometrics
Design
 Determine who the users are (the population)
 Determine the relevant body dimensions
 Determine the relevant percentage level
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Both male and female?
Is 5th-95th range too small?
Do you need both ends of the range for that problem?
Don’t just use 50th percentile
Anthropometrics
 Work Space Design
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Clearances: must accommodate the largest users
Reach envelopes: must consider minimum reach
Visibility: most comfortable visibility range
Work surface height: 5-10 cm below elbow
height (higher for precise work, lower for work
requiring force)
Link Analysis
 Technique for determining
arrangement
 Spatially organize
components
 Link by variable of interest
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B
C
P
M
travel time
frequency of use
 Thickness of link
represents variable
 Redesign to improve
variable of interest
P
C
B
M
Work Physiology
 Muscle Structure
 Aerobic vs Anaerobic
Activity
 Muscle Efficiency 20%
 Heart Parameters:
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Cardiac Output
Heart Rate
Stroke Volume
 Basal metabolic rate:
1600-1800 kcal/day
 Short Term (Aerobic) Work
Capacity
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about 15kcal/min men
10 kcal/min women
 Long Term Work Capacity
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suggested not over 1/3 of
short term for 8 hrs
 Designed Rest Schedules
Biomechanics of Work
 Statics model (F=0,
Moments=0), isometric contraction
 L5/S1 Lumbosacral Disc (p.329)
 Cumulative Trauma Disorders (CTDs)
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Fingers, hand/wrist, elbow, shoulder
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tendon irritation
muscle loading due to unnatural postures
blood obstruction
NIOSH Lifting Equation
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RWL = LC x HM x VM x DM x AM x FM x CM
LC: load constant, maximum recommended weight
HM: horizontal multiplier, decreases weight with distance from spine
VM: vertical multiplier, lifting from near floor harder
DM: distance multiplier, accommodates for vertical distance that must
be lifted
AM: asymmetric multiplier, reductions for torso twisting
CM: coupling modifier, depends on whether loads have handles for
lifting
FM: frequency modifier, how frequently is the load lifted
Multipliers can all be obtained from tables (11.1, 10.2, 10.3, 11.2, 11.3)
More
 Transportation
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Tasks in driving
Distractions and issues
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some causal factors to accidents
 Personnel selection
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Methods:
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Resume and Interview.
Behavioral interview
Various tests