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1Skin Architecture
Skin Architecture:
Michele Han
The Skin
The first line of defense, skin protects against infec-tion, abrasion, and water loss. It contains nerve endings vital for sensation, such as touch, pain, heat, and cold. It produces vitamin D on exposure to UV rays in sunlight, monitors the body’s salt balance, and regulates body temperature.
Skin is the body’s largest organ.
It is a boundary, separating man from environment. Adapting and responding, it maintains a constant equilibrium; it creates homeostasis.
The term homeostasis is referred to by Flood and Carson (1993) as a process by which a system preserves its existence through the maintenance of its dynamic equilibrium.
dermal papillae
illustrations from THE PEOPLE’S COMMON SENSE MEDICAL ADVISER IN PLAIN ENGLISH, FIFTY-FOURTH EDITION. R.V. Pierce, MD, 1895 <www.gutenberg.org/files/18467/18467-h/advise.html>
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Thermoregulation
Blood is shunted around the body to create a different heat distribution depending on the external climate, internal heat genera-tion and heat loss mechanisms.
Despite the extreme variance of environ-mental temperatures, the body restricts its core to a very narrow thermal range, the extremes of either of which is death.
The skin provides the interface by which the body controls this internal thermal environment. Embedded with sensors and equipped with an array of mechanistic re-sponses, the skin acts as a surface through which to radiate or absorb heat.
RISE IN CORE BODY TEMP
Receptors in hypothalamus detect increase in core temp/temp of blood
VASODILATION of arteriolesSHUNT VESSELS CONSTRICT increased blood flow to skin surface; heat loss by RADIATION Heat loss by EVAPORATION of sweat; sweating leads to a lower skin tempVOLUNTARY ACTION - remove clothing; seek cooler area; or cold drink
°F Human CoreTemperatures
86 Decreased shivering, erratic movements, incoherent93 Violent shivering; speech and thought impaired96 Intense shivering and Impaired coordination98 Normal Range100 Extreme physical exercise and fever107 Heat stroke, brain damage111 Upper limit for survival, impaired thermal regulation
February, South Pole Station -40
January, New York City 32
Cool bath 68
July, Yuma Arizona 86
Hot bath 104
July , Death Valley 122Hot beverage 140Hot desert sand 176Very hot sauna 212
Environmental Temperatures
°F
°F Human CoreTemperatures
86 Decreased shivering, erratic movements, incoherent93 Violent shivering; speech and thought impaired96 Intense shivering and Impaired coordination98 Normal Range100 Extreme physical exercise and fever107 Heat stroke, brain damage111 Upper limit for survival, impaired thermal regulation
February, South Pole Station -40
January, New York City 32
Cool bath 68
July, Yuma Arizona 86
Hot bath 104
July , Death Valley 122Hot beverage 140Hot desert sand 176Very hot sauna 212
Environmental Temperatures
°F
Thermal Ranges, adapted from “The Skin’s Role in Human Ther-moregulation and Comfort” (Edward A. Arens_ H. Zhang).
DROP IN CORE BODY TEMP
Receptors in hypothalamus detect increase in core temp/temp of blood.
VASOCONSTRICTION of capillaries in the skin narrowSHUNT VESSELS DILATE Less blood flows to skin surface = less heat is lost by RADIATIONHair raising - greater insulationShivering - rapid contraction and relaxation of muscles produces heat by RESPIRATIONAdrenaline INCREASES METABOLIC RATE of cellsVOLUNTARY ACTION - put on clothes; seek warmer areas or warm drink
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1400’
WINTERSUMMER
30’10° F
0° F
20° F
30° F
40° F
50° F
60° F
70° F
80° F
90° F
100° F
110° F
SUBWAY
The problem
Unfortunately, the NYC subway is not as efficient in its thermoregulation.
In the summer, when an underground tunnel would seem a refuge, temperatures commonly register 110 degrees on popular platforms – the human body, subjected to prolonged exposure to such heat risks heatstroke and brain damage.
“Sometimes it’s so hot on the platform that I can’t breathe. I would think the MTA would want to do something about the temperature on the platforms so they don’t have people passin’ out all over the place.” Victoria Jeter, Second Ave Sagas Blogger < http://secondavenuesagas.com/2007/07/11/key-temperature-question-conspicuously-absent-from-summer-subway-reports-cards/#comment-905>
“The Metropolitan Transportation Authority has tried to calculate the sources of this seasonal discomfort. It found that brakes produced 60 percent of the heat, air-conditioning provided 20 percent and accelera-tion 13 percent -- a total of 93 percent of the heat from the trains. Humans and electrical equipment (they are lumped into one category by the M.T.A. for the purposes of assessing heat, it seems) added only 7 percent to the mix.” “The City Life; Summer’s Infernal Subway, ELEANOR RANDOLPH. August 9, 1998. NEW YORK TIMES <http://query.nytimes.com/gst/fullpage.html?res=9C04E4D6103BF93AA3575BC0A96E958260>.
Air-conditioning - meant to temper the environment - only adds to the discomfort, producing 20% of platform heat gain.
The thermal mass of the ground acts as an insula-tor, preventing the dissipation of accumulated heat. Ventilation draws air in from the street, and vents it back; hot air produced within the subway tunnels is vented out onto the streets and sidewalks. Dur-ing the winter this might seem like a good thing, but during the summers it makes the city heat even more unbearable.
The proposal
This project looks at an alternate means of ventila-tion, using the regulatory properties of human skin as precedent to create a homeostatic environment within the new subway extension.
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BRONX
QUEENS
BROOKLYN
125 ST
116 ST
106 ST
96 ST
86 ST
72 ST
LEXINGTON-63 ST
57 ST
42 ST
34 ST
23 ST
14 ST
HOUSTAN ST
GRAND ST
CHATHAM SQ
SEAPORTHANOVER SQ
142 ST
FIFTH AVE
110 ST106 ST
96 ST
86 ST
72 ST
59 ST
FIFTH AVE
TENTH AVE
PARKSID
ETHIR
D AVE
FIRST A
VE
42 ST
34 ST
EIGHTH A
VESEVENTH A
VESIX
TH AVE32 ST
14 ST
BROADWAY
HU
DSO
N S
T
W. B
ROADWAY
FULTON ST
ROU
TE 9
A
DELANCEY ST
OFF-ISLAND TRANSFER STATIONS
ESTIMATED HEAT GAIN
2ND AVE TUNNEL EXTENSION
14TH ST SITE
The site:
NYC is currently building an extension to their subway network. The extension will follow Second Avenue, providing a new line of running N-S.
TRAIN MOVEMENT
compression
increased pressure
decreased pressure
atmospheric equilibrium
direction of propogation
tunnel entrance
high pressure
low pressure
Subway systems generate a tremendous amount of energy in the form of pressure differentials caused by the passing of subway trains.
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The model
A performative model was designed to explore a means of taping these pressure differentials.
A series of clear chambers equipped with permeable deformable membranes that animate the creation of pressure differentials and the direction of air flow.
check valves
pvc pump
plunger
tubing
pressure chambers
deformable membrane
A 2” pvc pipe was used to simulate a subway tunnel, with a 2” plastic plunger pump to simulate the pass-ing train.
Check valves direct and control the inlet and outlet of air. A check valve allows fluid (liquid or gas) to flow through it in only one direction. When the pump is set in motion, a high pressure compression wave pushes air out of the outlet valves in front of the plunger, while a low pressure wake behind the plunger draws air in through inlet valves.
DIRECTION
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As the pump passes, depending on the direction of the valve, air is pushed either in or out of the cham-bers. With each pass, the membrane separating the chambers deflects towards the side of lower pres-sure. When the pump ceases, air is diffused through the membranes. The result is a choreographed diffu-sion of air from high to low pressure, animated by the slowly deforming shapes of the membranes.
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The system
Applying this logic to the site, a network of check valves embedded throughout the Second Avenue tun-nel is used to channel air through a vascular system that uses the thermal mass of the earth to create a temperate subway environment.
As the train passes, tunnel inlet valves draw surface air in from the street level. The air is passed through filters to sift out particulates, and long pipes that use the constant temperature of the earth (approximately 50 degrees Fahrenheit) to temper the air.
This cleaned and tempered air is drawn through the stations into the tunnel, and expelled by outlet valves onto the sidewalks.
O2
CO2
COheat
StationTunnel
O2
SO2
NO2
O2
heat
UndergroundEnvironment
14th Street
2nd Ave
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Heat sensitive check valves control air inlet. If the temperature drops too far, the check valve closes. As more and more valves turn off, a flexible bladder behind the tunnel skin begins to inflate, constricting the space and reducing the volume of space to be heated. Valves re-open when the temperature rises.
air bladder
heat sensitive inlet valve
supply pipe
The thermal environment within each station is regu-lated by a double skin. The outer skin is embedded with heat sensitive check valves that control air inlet. Each valve contains an individual thermal sensor with a set-point range that determines whether the valve is on or off. It the local temperature drops too far below the set-point, the check valve closes and air cannot pass.
If more and more valves turn off, the inner skin of the station (comprised of a series of flexible bladders) begins to inflate. This inflation causes the outer skin (made up of sliding scales that expand or contract) to constrict. The result is a reduction of volume within the stations to be heated. As passing riders and trains re-heat that volume of space, valves re-open and the station walls expand.
H
L
pressure gradient
intakeout-take
subway station
tunnel pressure
wind
dispersion to station
train direction
HOT
COLD
HOT
Inlet Valves
ON
OFF
ON
Air Pressure, bladderStation Skin Sensors
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N
AB
H
L
pressure gradient
intakeout-take
subway station
tunnel pressure
wind
dispersion to station
train direction
Because each valve is independent of the others, localized environments of individualized shape, temperature and pressure within the Second Avenue Subway network will generate a dynamic equilibrium within the system, balancing not only temperature, but wind speed and flow as well.
!4th Street StationPlan
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References
Skin
illustrations from THE PEOPLE’S COMMON SENSE MEDICAL ADVISER IN PLAIN ENGLISH, FIFTY-FOURTH EDITION. R.V. Pierce, MD, 1895 <www.gutenberg.org/files/18467/18467-h/advise.html>
“Modelling and Simplification of a Human Thermoregulation Model for thermal comfort regulation in a car interior” Lakhdar Benasser, Genevieve Dauphin-Tanguy, & Jean-Christophe kat. Proceedings of the 1999 EEUASME International Conference on Advanced Intel-ligent Mechatronics September 19-23, 1999 Atlanta, USA.
“The Skin’s Role in Human Thermoregulation and Comfort” (Ed-ward A. Arens_ H. Zhang).
“Skin Blood Flow in Adult Human Thermoregulation: How It Works, When It Does Not, and Why” Nisha Charkoudian, PHD. Mayo Clinic Proceedings. 2003;78:603-612
“Thermal sensation and Thermoregulation” Professor Alan Hedge, Cornell University, January 2007
Histologic Diagnosis of Inflammatory Skin Diseases, A. Bernard Ackerman, Almut Böer, Bruce Bennin, and Geoffrey J. Gottlieb. 2002–2006 Ardor Scribendi, Ltd. <http://www.derm101.com/public/freesamples/inflam001.html>
Subway
“Design of a modern subway ventilation system.” Tunnels & Tun-neling International NOVEMBER 2004. (pg 48-50)
MTA Capital Construction - Second Avenue Subway Planning Study. <http://www.mta.info/capconstr/sas/sas_documents.htm>
“Fainting dieters a top cause of NYC subway delays”Posted By Gina Pellrine, 9 January 2007. <http://www.thefinalsprint.com/2007/01/fainting-dieters-a-top-cause-of-nyc-subway-de-lays/>
Arup Capability Statement, Consultancy Services for Ventila-tion, Aerodynamics, Fire Smoke Control and MEP Systems in Tunnels.<www.arup.com/industrial>
“Analysis of Flow and Transport in Subway Systems”, W. E. Dunn,* B. R. Green U.S. Army, DOE ANL 980072401
“Manhattan East Side Transit Alternatives (MESA)/Second Avenue Subway Summary Report”, MTA New York City Transit, Vollmer Associates, LLP SYSTRA Consulting, Inc. Allee King Rosen & Flem-ing, Inc. October 2001
“The City Life; Summer's Infernal Subway, ELEANOR RANDOLPH. August 9, 1998. NEW YORK TIMES <http://query.nytimes.com/gst/fullpage.html?res=9C04E4D6103BF93AA3575BC0A96E958260>.