# Five Elements 🔥 五行元素

Chinese people believe that we are surrounded by five energy fields or five different kinds of “Qì” (气). These are also called the “five elements” and they play an important role in all aspects of Chinese culture, including the way people eat. This theory states that if these five elements are changed or moved, this could seriously affect a person’s fate.

# Predict Failure 🛟 预测失效

Maximum Normal Stress CriterionThe maximum stress criterion, also known as the normal stress, Coulomb, or Rankine criterion, is often used to predict the failure of brittle materials.

# Riemann Hypothesis 🎓 黎曼猜想

Riemann hypothesis, in number theory, hypothesis by German mathematician Bernhard Riemann concerning the location of solutions to the Riemann zeta function, which is connected to the prime number theorem and has important implications for the distribution of prime numbers. Riemann included the hypothesis in a paper, “Ueber die Anzahl der Primzahlen unter einer gegebenen Grösse” (“On the Number of Prime Numbers Less Than a Given Quantity”), published in the November 1859 edition of Monatsberichte der Berliner Akademie (“Monthly Review of the Berlin Academy”).

# Divergence & Curl ➰ 散度和旋度

DivergenceDivergence is an operation on a vector field that tells us how the field behaves toward or away from a point. Locally, the divergence of a vector field $\vec{F}$ in $\mathbb{R}^2$ or $\mathbb{R}^3$ at a particular point $P$ is a measure of the “outflowing-ness” of the vector field at $P$.If $\vec{F}$ represents the velocity of a fluid, then the divergence of $\vec{F}$ at $P$ measures the net rate of change with respect to time of the amount of fluid flowing away from $P$ (the tendency of the fluid to flow “out of” P). In particular, if the amount of fluid flowing into $P$ is the same as the amount flowing out, then the divergence at $P$ is zero.

# Antenna 📡 天线

Antennas are widely used in the field of telecommunications and we know many applications for them. Antennas receive an electromagnetic wave and convert it to an electric signal, or receive an electric signal and radiate it as an electromagnetic wave.

In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays.

# Colored Pencils 🖍️ 彩铅

There’s a lot to like about drawing with colored pencils. They’re utterly convenient—a handful of colored pencils and a pad of paper are all you really need to start creating. Prep time and cleanup are practically non-issues, the materials are light and portable, and you don’t need messy or toxic solvents. At the same time, colored pencil drawing lends itself to highly refined and exquisite works of art that rival those created with any other medium.

# Inception 💤 盗梦空间

A thief who steals corporate secrets through the use of dream-sharing technology is given the inverse task of planting an idea into the mind of a C.E.O.

# Nunchaku 🥋 双截棍

The Handcrafted Nunchaku or nunchucks (Japanese: ヌンチャク nunchaku, often “nunchuks“, “chainsticks“, “chuka sticks” or “karate sticks” in English) is a traditional Okinawan martial arts weapon consisting of two sticks connected at one end by a short chain or rope. The two sections of the weapon are commonly made out of wood, while the link is a cord or a metal chain. The nunchaku is most widely used in martial arts such as Okinawan kobudō and karate, and is used as a training weapon, since it allows the development of quicker hand movements and improves posture. Modern-day nunchaku can be made from metal, wood, plastic or fiberglass. Toy and replica versions made of polystyrene foam or plastic are also available. Possession of this weapon is illegal in some countries, except for use in professional martial art schools.

# Pencil Sketch ✍️ 素描

A pencil is an implement for writing or drawing, constructed of a narrow, solid pigment core in a protective casing that prevents the core from being broken or marking the user’s hand. Pencils create marks by physical abrasion, leaving a trail of solid core material that adheres to a sheet of paper or other surface. They are distinct from pens, which dispense liquid or gel ink onto the marked surface.