相关概念视频

Proofreading01:43

Proofreading

Overview
52.0K
The Retina01:32

The Retina

The retina is a layer of nervous tissue at the back of the eye that transduces light into neural signals. This process, called phototransduction, is carried out by rod and cone photoreceptor cells in the back of the retina.
56.6K
Frequency-dependent Selection01:21

Frequency-dependent Selection

When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
20.1K
The Scope of Physics01:17

The Scope of Physics

Physics is concerned with the interactions of energy, matter, space, and time, in order to discover the underlying mechanisms that underpin all phenomena. The word "physics" comes from the Greek word "phúsis", which means nature. Physics seeks to comprehend the natural world around us at its most fundamental level. It emphasizes the use of quantitative laws to do this, which could be valuable in other fields that want to push the performance boundaries of present...
40.1K
Journal Bearings01:23

Journal Bearings

Journal bearings are mechanical components that support and provide lateral stability to rotating shafts and axles. They are crucial in reducing friction, wear, and vibration in machinery such as engines, turbines, and pumps. The principle behind journal bearings is forming a thin lubricant film between the bearing surface and the rotating shaft, which minimizes direct contact and reduces frictional forces.
To better understand the concept of journal bearings, consider a rope winch with dry or...
1.6K
Impact Loading on a Cantilever Beam01:13

Impact Loading on a Cantilever Beam

The analysis of a cantilever beam with a circular cross-section subjected to impact loading at its free end illustrates the conversion of potential energy from a dropped object into kinetic energy, which is then absorbed by the beam as strain energy. This process is crucial for understanding how materials behave under dynamic loads, which is important in fields such as construction and aerospace.
When an object is dropped onto the free end of a cantilever, its potential energy due to gravity is...
1.2K