相关概念视频
Second Order systems II
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In an underdamped second-order system, where the damping ratio ζ is between 0 and 1, a unit-step input results in a transfer function that, when transformed using the inverse Laplace method, reveals the output response. The output exhibits a damped sinusoidal oscillation, and the difference between the input and output is termed the error signal. This error signal also demonstrates damped oscillatory behavior. Eventually, as the system reaches a steady state, the error diminishes to zero.
96
Second Order systems I
139
A servo system exemplifies a second-order system, featuring a proportional controller and load elements that ensure the output position aligns with the input position. The relationship between these components is described by a second-order differential equation. Applying the Laplace transform under zero initial conditions yields the transfer function, showing how inputs are converted to outputs in the system.
By reinterpreting the system, one can derive the closed-loop transfer function, which...
By reinterpreting the system, one can derive the closed-loop transfer function, which...
139
First Order Systems
87
First-order systems, such as RC circuits, are foundational in understanding dynamic systems due to their straightforward input-output relationship. Analyzing their responses to different input functions under zero initial conditions reveals significant insights into system behavior.
When a first-order system is subjected to a unit-step input, its response is characterized by its transfer function. By applying the Laplace transform of the unit-step input to the transfer function, expanding the...
When a first-order system is subjected to a unit-step input, its response is characterized by its transfer function. By applying the Laplace transform of the unit-step input to the transfer function, expanding the...
87
Nuclear Fusion
18.6K
The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
18.6K
Nuclear Stability
18.7K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
To hold positively charged protons together...
18.7K
Nuclear Transmutation
17.5K
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed...
17.5K
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对于Ic型超新星的二进制祖先系统.
Martín Solar1, Michał J Michałowski2, Jakub Nadolny3
1Astronomical Observatory Institute, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland. martin.solar@amu.edu.pl.
Nature communications
|September 3, 2024
概括
核心崩超新星,包括II类和Ic类,发生在类似的气体密度中,这表明原始质量相似. 这支持Type Ic超新星的二进制相互作用,影响银河系进化模型.
科学领域:
- 天体物理学和宇宙学.
- 恒星进化和超新星的发生
- 银河系进化过程中的进化.
背景情况:
- 核心崩的超新星对于银河系的化学丰富和调节恒星形成至关重要.
- 关于Ic型超新星 (缺乏H/He线) 的原始性质仍在争论中,其中可能包括非常大质量的恒星或双星系统.
研究的目的:
- 通过将其环境与II型超新星的环境进行比较,研究Ic型超新星的原始起源.
- 为了解决关于Type Ic祖先是单个质量巨大的恒星还是二进制相互作用的产物的争论.
主要方法:
- 在II型和Ic型超新星的环境中分析分子气体密度.
- 基于环境特性的祖先生命周期和初始质量的比较.
主要成果:
- 类型II和类型Ic的超新星存在于具有相似分子气体密度的环境中.
- 这种相似性意味着两种超新星类型的祖先寿命和初始质量都相当.
- 这些发现支持二进制相互作用作为大多数Ic型超新星祖先的主要道.
结论:
- 类似的环境表明,Ic型超新星并不完全来自非常大质量的单一恒星.
- 二元相互作用为观察到的Ic型超新星的光谱特征 (缺乏H/He线) 提供了一致的解释.
- 这些结果可以在宇宙学模拟中改进子网格模型,以改进反和化学混合计算.


