The idea is derived from mass balance. Humid outside air entering the house displaces dryer conditioned air leaving the house. If you measure humidity inside and outside, calculate the partial pressure of H2O vapor inside and outside, measure the condensed liquid from your dehumidifier or A/C drain, voila, you know the rate of air exchange.
This is far from my own idea -- I read about it in a government report that came about in the "1st Energy Crisis" of the 70's and early 80's in the wake of the OPEC oil embargo followed by the Iranian Revolution. The usual way to measure air infiltration is with a blower door, but this way seems to require less fuss. The air infiltration number by this method, however, are "all over the place."
What went wrong? I don't have any incontrovertible "science" quantifying any of this, but I have some guesses, hypotheses to some people, beliefs to others. One, the amount of air infiltration varies with wind speed. The whole idea behind the blower door is you apply a pressure differential way in excess of the wind pressure on the day of the test to control for that. Two, and this is just an intuition, the single-compartment model must be wrong. The walls of your house act as a sink for moisture, one that is ambient temperature dependent and also has significant lags in exchanging moisture with the inside air. Three, family members add humidity by bathing, cooking, and simply breathing, but I tried to control for this by taking measurements when I was alone and limiting time of showers, etc.
I simply gave up on this method. The effect that air exchange will either increase the humidity level of the house or increase the water in your dehumidifier bucket is "science", yes, but it is a kind of incontrovertible hard science of mass balance. On the other hand, the effect I tried to measure appeared to be swamped by these effects for which I was unable to control. Furthermore, countering confirmation bias took a great effort of will -- you get these "runs" that "don't make sense" and then you get a run consistent with the model, and you go "aha, this makes sense, this is the infiltration level of this house." It is kind of like someone asks you "what kind of gas mileage you getting from your new car" and you report a favorable high reading from memory instead an average from your receipts and odometer reading showing a much lower number.
Yes, there is the contingent that dares, "Take my SUV away when you pry my cold, dead fingers off the steering wheel." But there is also a contingent that knows how much the global temperature has increased in the last century and why, and when challenged starts getting all huffy and starts using four-letter words.
Seriously, that is my point. Feet, yards, pints, pounds (yeah, pound mass or pound weight, and what value and units are you using for G?) are human scale units. Meters (metres?), litres, grams, what are those? Those are made-up by some wild dudes in France in the late 18th century, and if you really wanted to scold USians about not "going metric", whatever happened to that fancy decimal calendar?
24 hr clock, tell me about it. If you really wanted to go G.I., you would schedule all your appointments in "Zulu time", which is pretty much local time for England and parts of Europe but completely artificial for the Continental U.S..
Those cultures that "have it together" divide the year into 10 "months", the month into 10-day "decades", and measure time with 10-hour days.
Metric makes perfect sense, and it is a mystery as to the holdouts against metric time.
So eating is a basic necessity of life, and we need to provide a social safety net that people don not starve, but meals above a bare subsistence level are a luxury good?
I have heard Conservatives argue that instead of Welfare and Foodstamps, we should just have these government stores where everyone can purchase as much whole-wheat flour, lard, and powdered milk as they want, and if a person wanted more than these subsistence food items, they should just get off the couch and work a few hours?
Actually, this plan has been tried out. I heard that "fry bread" became a Native American specialty owing to a Federal food program. Many Native Americans bear the genetic legacy of their ancestors being hunters adapted to feast-or-famine, where the modern diet leads to Type 2 Diabetes and other problems, but the Federal program was well-meaning, and I am getting off topic.
Oh, and then there is cheese, Reagan's cheese. Reagan got to cut back on the safety net and make up for it with free cheese -- solved the ag surplus and urban hunger problems in one step. I actually got to eat some -- Mom told me "you're eating it" when Grandma queued up at the Senior Center for the cheese and she put packets of it in Christmas baskets for the college-bound grandkids. Mmmm, mmm, mmm, that was good eatin'!
Oh, did I tell you that illegal drugs are one of the great social burdens that society has the duty to discourage any way it can? Yeah, yeah, most of the harm from drugs comes from the War on Drugs -- highest incarceration rate among our trading partners, dirty needles/impure drugs, racial impact, police corruption -- but if these drugs were not illegal, everyone would stay at home stoned out of their minds and no work would get done, like China under the British thumb? Besides, a drug habit is really a "luxury good" that you can get by without if you are poor, and if you are wealthy, you can afford the cost of rehab when addiction gets the better of you?
So here is what a Midwestern governor wants to do next -- drug-test food-aid recipients.
So here I am, working for my food, being very careful to eat healthy and stay within a budget, and I am in line behind a rag-proletarian buying all manners of expensive junk food who pulls out an EBT card? And you know a lot of that "stuff" gets traded for drugs? Why should a government food program support beyond the bare necessities of wheat flour, lard, and dry milk -- anything more is a luxury. Twinkies and sodas are certainly a luxury offering personal harm and social harm when he have to pay for your dialysis, whether consumed directly for a sugar-high or traded for a more industrial-strength high?
The argument against what the Governor wants to do (apart from the chance of being blown up in a court challenge on Equal Protection and Unreasonable Search and Seizure grounds) is human dignity. You have people who need government aid to buy food who probably have a drab life to begin with, and you (well, maybe not you, but the Right Wing) want to deny them the pleasure of eating Froot Loops. Deny them the personal choice between spending their EBT funds on Froot Loops or substituting Mom's Best Wheat Squares (a "generic" no added-sugar no-salt whole grain alternative)?
What the Right Wing wants to do with the poor, others want to impose on the Middle Class? So a personal auto is deemed monumentally destructive, but have you checked out the Federal stats on transit districts and that owing to off-peak service, deadhead return trips during rush hour, a Diesel bus breaks even with a two-person carpool in CO2 emissions? You want all of those excise taxes and our Governor wants to trade food for a sample of your bodily fluids? What price human dignity? What price human liberty?
These are not the Higgs' you're looking for . . .
(Associate Editor turns towards reviewers) Let their paper through . . .
Thank you, Melinda French Gates . . .
The classic "holding pattern" where planes are "stacked up" at different altitudes but at the same radio beacon (VOR) intersection works like this. You fly straight for one minute, execute a 180 deg right turn for one minute, fly straight for another minute, and then execute another 1 minute right turn to complete the circuit. This is often done inside the clouds -- if there were good weather, you would not be in a holding pattern. Repeat until the passenger barf.
You see, after Reagan fired all the air traffic controllers and broke the strike with replacement workers, the FAA replaced most holding patterns with ground holds, where you are just sitting at the departure gate getting anxious about your 30-minute connection in Detroit.
At least sitting on the ground isn't wasting fuel, using up the fuel needed to fly the plane, and is generally safer than this "circling" (actually, "ovaling").
There is no "line" at McDonalds, there is simply a mob of customers, some of them waiting for their order, some of them staring at the menu-on-the-wall not knowing what to order, and some eager to purchase something and eat. Somehow that mob is self-organizing and the servers are able to "Can I help you?" the next person without a line and without starting a riot.
The one time that didn't work is when I was on a long drive returning from visiting my parents in "long-term care", and as I came up to the counter to open my mouth with my order, a group of people from what looked like a middle-school sports team after a game simply surged passed me, as much as pushing me aside. Didn't say anything but from my scowl, one of them remarked, "I bet that 'dude' is upset" only in somewhat more vulgar terms. I think I said something that I had a 'long day', was very tired and hungry beyond belief, but it didn't look like I was getting anything to eat anytime soon, I turned and left.
Before someone lectures me about my sense of entitlement, that was probably an epic fail of this "store" from their training at Hamburger U. I don't stop there but instead patronize another McDonalds a little further up the road with which I have good experience.
It's not the hydrogen, it is everything else that is wrong about it.
The US Navy had these Zeppelin clones, and they crashed every one save the Los Angeles from flying into bad weather, which for a rigid airship, appears to be anything other than a perfect sunny day.
Commander Shepard, I guess, was bolted into the rocket for so long he had to "do it in the suit."
To squelch the rumors, the story told is that the Soviets then played tapes of vocal choruses. No one would believe that they orbited the entire Soviet Army Men's Choral Group . . .
Or at least that used to be the system until SARS/H1N1. Has this changed? Will an airline cheerfully let you reschedule if you tell them you have a fever and a bad sore throat, or do they demand "a doctor's note"?
When someone is trying to tell me they don't want to discuss this any further and this is the end of the conversation, that is when I really start to worry.