This TIME article says the main concern about whole milk is its high calorie content, which is actually weak in data support. One assertion is, the fat in whole milk makes us feel full and want to eat no more, thus is good for our waistline.
The BAIDU zhidao page is another recommender for whole milk. 全脂牛奶的脂肪含量是3.0%，半脱脂奶的脂肪含量大约是1.5%，全脱脂奶的脂肪含量低到0.5%。国外有一种“浓厚奶”，脂肪含量可高达4.0%以上。
Build a couple projects and be able to show them off.
Talk about decisions and reasons for making certain design or development choices.
Look at someone else's work and find areas that you'd be able to improve.
Go on Stack Exchange or similar and answer more questions than you need to ask.
Maths in Life
Suppose the annual interest rate is $r$, the total number of years is $n$, we borrowed $m$, and the total sum we need to pay back is $s$. So,
$$ s = m \times (1+r)^n$$
For example, we borrowed 50,000, and the annual rate is 4%, after 3 years, we need to pay back:
$$ s = 5 \times 1.04 ^ 3 $$
$$ s = 5 \times 1.12486 = 5.62430 $$
If we calculate in a lazy way (not compound interest 复利):
$$ s = m \times (1+rn) $$
And with compound interest:
$$ (1+r)^n = 1 + C_n^1 r + C_n^2 r^2 + \ldots $$
$$ (1+r)^n = 1 + nr + \ldots $$
Take the previous example, $1.04^3 - (1 + 0.04\times 3) = 0.12486 - 0.12 = 0.00486$. The error is small.
SPF (Sun Protection Factor) measures sunscreen protection from UVB rays, the kind that cause sunburn and contribute to skin cancer.
SPF does not measure how well a sunscreen will protect from UVA rays, which are also damaging and dangerous.
Dermatologists recommend using a SPF15 or SPF30 sunscreen. Higher SPFs don't give much more protection.
If your skin would normally burn after 10 minutes in the sun, applying an SPF 15 sunscreen would allow you to stay in the sun without burning for approximately 150 minutes (a factor of 15 times longer).
For best protection, experts recommend:
Using a minimum SPF sunscreen of 15,
applying the proper amount (2mg/cm2 of skin, or about one ounce for full body coverage)
reapplying every 2 hours. Or immediately after swimming or excessive sweating.
Do not burn.
Avoid tanning and UV tanning booths.
Usa a broad spectrum (UVA/UVB) sunscreen with an SPF of 15 or higher every day. For extended outdoor activity, use a water-resistant, broad spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher.
Keep newborns out of the sun. Sunscreens should be used on babies over the age of six months.
Using half the required amount of sunscreen only provides the square root of the SPF. So, a half application of an SPF 30 sunscreen only provides an effective SPF of 5.5!
The SPF (Sun Protection Factor) scale is not linear: SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97% of UVB rays, SPF 50 blocks 98% of UVB rays.
Why not use a really high Sun Protection Factor?
Sunscreens with really high SPFs, such as SPF 75 or SPF 100, do not offer significantly greater protection than SPF 30 and mislead people into thinking they have more protection than they actually do. Additionally, in order to have broad spectrum protection, the UVA protection should be at least 1/3 of the UVB protection. High SPF sunscreens usually offer far greater UVB than UVA protection, thus offering a false sense of full protection.
UVA at 320-400 nanometers. UVA is further divided into two wave ranges, UVA I, which measures 340-400 nanometers, and UVA II which extends from 320-340 nanometers.
UVB ranges from 290 to 320 nm.
With even shorter rays, most UVC is absorbed by the ozone layer and does not reach the earth.
Both UVA and UVB, however, penetrate the atmosphere and play an important role in conditions such as premature skin aging, eye damage (including cataracts), and skin cancers. They also suppress the immune system, reducing your ability to fight off these and other maladies.
Lithium ion battery
wikipedia. Lithium-ion batteries are common in home electronics. They are one of the most popular types of rechargeable batteries for portable electronics, with a high energy density, tiny memory effect and low self-discharge.
The lifetime of lithium batteries decreases at higher temperature and states of charge (SoC), whether used or not; maximum life of lithium cells when not in use(storage) is achieved by refrigerating (without freezing) charged to 30%-50% SoC.
The World Geodetic System (WGS) is a standard for use in cartography, geodesy, and navigation including by GPS.
It comprises a standard coordinate system for the Earth, a standard spheroidal reference surface (the datum or reference ellipsoid) for raw altitude data, and a gravitational equipotential surface (the geoid) that defines the nominal sea level.
The latest revision is WGS 84 (aka WGS 1984, EPSG:4326), established in 1984 and last revised in 2004.
WGS 84 is the reference coordinate system used by the Global Positioning System.
The coordinate origin of WGS 84 is meant to be located at the Earth's center of mass; the error is believed to be less than 2 cm.
Google map offset in China
polastre. Yes there it is. It says it is done intentionally from cold war.
Inductive Charging 无线充电
Wikipedia. Induction chargers use an induction coil to create an alternating electromagnetic field from within a charging base, and a second induction coil in the portable device takes power from the electromagnetic field and converts it back into electric current to charge the battery. The two induction coils in proximity combine to form an electrical transformer.
Greater distances between sender and receiver coils can be achieved when the inductive charging system uses resonant inductive coupling.