ec review 2 Flashcards
1
Q
how does sound travel
A
source, path, receiver
2
Q
what is sound
A
frequency, pitch, wavelength
amplitude, volume, loudness
1000 Hz = 1 ft
3
Q
human range of hearing
A
20 Hz - 20,000 Hz
4
Q
wavelength
A
distance sound travels in 1 second
5
Q
frequency
A
the number of times a sound source vibrates per second; units are Hz, (or cycles per second or cps)
6
Q
pitch
A
musical term for frequency; a high-frequency sound has a high pitch
7
Q
how does age affect hearing
A
older people cannot hear as high frequencies as younger people
8
Q
how does echolocation work
A
time delays, doppler shifts, frequency information
9
Q
what is sound (bullet points)
A
- form of energy that travels in waves
- audible signal
- vibrations that travel through a medium and can be heard when they reach an ear
- mechanical wave
- oscillation of pressure that is transmitted through a solid, liquid, or gas within the range of hearing
10
Q
what is vibration
A
- sound is heard, vibration is felt
- typically less than 20 Hz
11
Q
diffraction
A
- high frequency sound = small diffraction
- mid frequency sound = medium diffraction
- low frequency sound = large diffraction
12
Q
sound masking
A
- white noise
- pink noise
- vegetation
13
Q
sound intensity
A
measure of the sound energy passing a unit area in a unit time
(measured in watts per meters squared)
14
Q
loudness
A
subjective human perception of sound amplitude; based on strength of the sensation received by the eardrum and sent to the brain
15
Q
loudness is dependent on
A
- distance from the source (inverse square law)
- amplitude and frequency of the vibration (source)
- density of the medium (path)
- biology of the individual (receiver)
- presence of masking
16
Q
sound power measure
A
watt (w)
17
Q
sound pressure measure
A
Pa (pascal)
18
Q
sound intensity measure
A
w/cm^2
19
Q
sound power
A
- output
- characteristic of the source
- measured in watts of acoustic power
- jet engine: 100,000w
- orchestra: 10w
- speech: 0.00001w
20
Q
sound pressure
A
- effect of a sound at a particular location
- ambient air pressure deviation (pascals)
- near jet engine: 200 Pa
- loud nightclub: 2 Pa
- speech: 0.02 Pa
21
Q
loudness: inverse square law
A
I = P/A
distance from the source
22
Q
double/half of source power
A
+/- 3 dB
23
Q
double/half distance from source
A
+/- 6 dB
24
Q
density of the medium (path)
A
- denser the medium, the more intense the wave
- faster the wave travels, the more quickly it transmits energy
- sound intensity is less measure of amount of energy, more of the rate energy transfer
25
noise
unwanted sound
26
hearing
perception of sound
27
sound reflectance
hard surfaces
28
sound transmittance & absorptance
soft surfaces
29
reverberation vs articulation
the persistence of a previously generated sound as it reflects off surrounding surfaces
30
reverberation time
the time required for a sound to reduce 60 dB; units are seconds
31
echo
a discrete reflection of a sound, usually delayed 1/10th of a second or more
32
reverberation
more continuous reflection of sound, over shorter time spans
33
absorption
fibrous materials, panel resonators, volume resonators (helmholtz resonators)
34
absorption strategies (in increasing effectiveness)
1. directly to room surface
2. hung below ceilings and away from walls
3. hung below ceilings as louvers, baffles
4. shapes suspended from ceilings
- spread out absorptive material as much as possible, avoid concentrating in one or a few locations
- treat 3 principle surfaces (ceiling, floor, and back wall) if possible
- if trying to reflect sound in a space, do not put absorptive material near source
35
SAC (sound absorption coeffiecient) a (alpha)
- ratio (no units)
- 1.0 = 100% absorption
- 0.0 = 100% reflection
SABINS (total absorption) = S x a
- S = surface area (material)
- 1 SABIN = 1 ft^2 of open window
A (total absorption) = S1a1 + S2a2 + S3a3 + ...
36
NRC (noise reduction coefficient)
- average sound absorption coefficient measured at frequencies between 250 and 2000 Hz
- not effective if high or low frequencies are important
- two materials with the same NRC can have very different acoustic properties
- measurement of sound absorption (not noise reduction)
37
Calculating Reverberation Time
Tr = KV/A
- K = 0.05 (for ft^2), 0.16 (for m^2)
- V = room volume
- A total absorption (S1a1 + S2a2 + ...)
38
calculating reverberation time
1. look up NRC values for each material
2. calculate square footages for each material
3. put it all together
39
voltage
- electrical potential or potential difference described in volts
- water analogy: pressure
- due to a magnetic field
- different than flowing energy
40
current
- movement of electrical charge
- water analogy: flow
41
AC vs DC
AC: alternating current
DC: direct current
42
who helped invent electricity
tesla & edison
43
power
- ability to act or produce and effect
- combination of current and voltage
- P = IV
- P (watts)
- I (amps)
- V (volts)
44
resistance
- measure of difficulty to pass an electric current through that conductor
- measured in ohms
- relationship between current, voltage, and resistance
- V = IR
- V: voltage (volts)
- I: current (amps)
- R: resistance (ohms)
45
single phase vs 3 phase
- single phase: most common for small construction
- three phase: more useful for large machinery because of cost
46
induction
magnet & wire coil
47
types of induction
- heat driven: natural gas, coal, nuclear, geothermal, geothermal CO2, combined heat and power, solar heating
- mechanical driven: hydroelectric, wave motion, wind power
48
photo electric reactions
solar power
49
solar cells
- multicrystaline vs monocrystaline
- duck curve
50
how is electricity stored?
- chemical storage
-- large scale battery storage
-- commercial small scale battery storage
-- DIY small scale battery storage
-- EV's as storage
- mechanical potential
-- hydro batteries
-- masonry batteries
51
how is electricity transmitted?
P = I^2R
I = current
52
voltages of power
- high (HV), extra-high (EHV), and ulta-high (UHV), 115,000 to 1,100,000 VAC
- medium voltage (MV), 2,400 to 69,000 VAC
- low voltage (LV), 240 to 600 VAC
53
why care about electricity and architecture?
- space planning
- estimating
- design
- safety
- reading plans
- receptacles
54
receptacles
- typically provide 120V single-phase power
- for wire sizing receptacles are counted at 2 amps each unless the load is known
- typically have hot, neutral, and ground wires attached
55
wiring
- comes in sizes ranging from 40 AWG (American Wire Guage) to 4/0 AWG
- Most common sizes for architectural use range between 12 AWG and 4/0 AWG
- wire size decreases as the wire gauge number increases (12 AWG is smaller than 10 AWG, etc)
56
switching
- complete an electric circuit
- can be used to switch light recptacles equipment
- four common switch types: on/off, dimmer, occupancy sensor, scene selector
57
breakers
- all electricity in a building flows through a breaker box
- each circuit is sized to take a load in your building
- standard breaker size is 20 amps
- breakers "trip" when amperage higher than its rating is drawn through it during a short circuit
- single pole, two pole, three pole
58
grounding
- connection of your outlet to the physical ground
- round plug on your standard 3 hole outlet
- is in place in case what you are plugging in has a short in the housing
59
electrification
- 2 fold goals:
--get all the grid power free of greenhouse gas emissions
-- make all our tools, vehicles, and appliances electric
- its not possible to have a gasoline car with zero emissions, but it is possible to have an electric car with zero emissions if the grid has none
60
internet of things
- allows for more control of how an when our devices use energy
- can allow power companies to have more say in how their power is used
- potential privacy concerns
61
internally load dominated
- surface area to volume is small
- large loads (computing, manufacturing, etc)
- usually, but not necessarily, less glazing
- usually places of work
62
externally load dominated
- surface area to volume large
- smaller loads
- more glazing
- usually places of living
63
why we need security?
- natural disasters: fire, earthquake, flooding, wind
- manmade threats: explosions, break ins, person to person violence
64
responses to threats
- building shell: wind protection, security glass
- flexible structure: earthquake
- warning systems: fire, storm, violence
- egress
-site design: water
- crime prevention through environmental design (CPTED)
65
Crime prevention through environmental design (CPTED)
1. natural access control
2. natrual surveillance
3. territoriality
4. maintenance
66
entry = access control
- locks
- automatic door closers
- operable windows
- bollards
- fencing
67
visibilty = natural surveillance
- lights
- camera
- no blocked sight lines
- monitored entrance
- glazing
68
this space matters = territoriality
- borders
- public art
- signage
69
does anyone care anymore = maintenance
- graffiti
- trash
70
signage
- exterior signage
- interior signage
71
maintenance safety
- guardrails
- clearance
- lockotus
