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相关概念视频

Non-uniform Circular Motion01:22

Non-uniform Circular Motion

In uniform circular motion, the particle executing circular motion has a constant speed, and the circle is at a fixed radius. However, not all circular motion occurs at a constant speed. A particle can travel in a circle and speed up or slow down, showing an acceleration in the direction of motion. In that case, the motion is called non-uniform circular motion, and an additional acceleration is introduced, which is in the direction tangential to the circle. 
For example, such accelerations...
Angle of Twist: Problem Solving01:13

Angle of Twist: Problem Solving

An electric motor applies a torque of 700 N·m to an aluminum shaft, triggering a stable rotation. Two pulleys, B and C, are subjected to torques of 300 N·m and 400 N·m, respectively. The modulus of rigidity is provided as 25 GPa. With the knowledge of the length and diameter of each segment, the twist angle between the two pulleys can be computed. First, a section cut is made between pulleys B and C, and the cut cross-section is analyzed using a free-body diagram. Given that the torque exerted...
Design of Transmission Shafts01:16

Design of Transmission Shafts

The design of a transmission shaft is governed by two primary specifications: the power it transmits and its rotational speed. These parameters guide the selection of the shaft's material and cross-sectional dimensions, ensuring that the material's maximum shearing stress remains within the elastic limit while transmitting the desired power at the given speed. The system's power is intrinsically linked to the applied torque. The torque applied to the shaft can be calculated by reconfiguring the...
Transmission Shafts: Problem Solving01:09

Transmission Shafts: Problem Solving

Designing a solid shaft that transmits power from a motor to a machine tool involves a series of calculations to ensure the shaft can withstand the stresses applied by bending moments and torques. First, calculate the torque exerted on the gear, considering the power transmitted by the shaft and its rotational speed. Following this, compute the tangential forces acting on the gears, which directly relate to the torque and the gear radius.
Next, use bending moment diagrams for the shaft to...
The Swing Equation01:21

The Swing Equation

The Swing Equation is a fundamental tool in power system dynamics, especially for analyzing the behavior of generating units like three-phase synchronous generators. This equation emerges from applying Newton's second law to the rotor of a generator, encompassing factors such as inertia, angular acceleration, and the interplay between mechanical and electrical torques.
In a steady-state operation, the mechanical torque (Τm) supplied to the generator is balanced by the electrical torque (Τe)...
Higher Derivatives01:29

Higher Derivatives

In calculus, higher-order derivatives extend the idea of differentiation beyond the first derivative to capture successive rates of change. These derivatives provide detailed information about the behavior of functions and have important applications in both mathematics and physics. To illustrate these concepts, consider the example function\begin{equation*}f(x) = x^3 - x\end{equation*}which serves as a useful case study for exploring higher derivatives.The first derivative represents the slope...

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相关实验视频

Updated: Jun 26, 2026

Method to Measure Tone of Axial and Proximal Muscle
10:41

Method to Measure Tone of Axial and Proximal Muscle

Published on: December 14, 2011

螺旋形变速器是什么意思

Dean J Tantillo1, Roald Hoffmann

  • 1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA.

Journal of the American Chemical Society
|June 13, 2002
PubMed
概括
此摘要是机器生成的。

我们计算了螺旋型聚烯中转移的激活障碍. 该研究预测,特定螺旋形状的[1,7]-shiftamers的低阻碍值为~14kcal/mol.

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相关实验视频

Last Updated: Jun 26, 2026

Method to Measure Tone of Axial and Proximal Muscle
10:41

Method to Measure Tone of Axial and Proximal Muscle

Published on: December 14, 2011

Fabrication Process of Silicone-based Dielectric Elastomer Actuators
10:32

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

Published on: February 1, 2016

A Rapid Method for Modeling a Variable Cycle Engine
04:58

A Rapid Method for Modeling a Variable Cycle Engine

Published on: August 13, 2019

科学领域:

  • 有机化学 有机化学
  • 计算化学的计算化学
  • 聚合物科学 聚合物科学

背景情况:

  • 螺旋型聚烯是具有独特结构性质的复杂有机分子.
  • 转移是有机化学中的基本反应,影响分子转变.
  • 了解聚烯的反应机制对于设计新材料和催化剂至关重要.

研究的目的:

  • 为了计算螺旋型聚烯中面间[1,7]-转移的激活障碍.
  • 为了研究和基结构对这些转移的影响.
  • 为了预测无限聚烯系统 ([1,7]-shiftamer) 中的转移屏障.

主要方法:

  • 使用计算化学方法来建模和计算激活障碍.
  • 密度函数理论 (DFT) 可能用于电子结构计算.
  • 分析的重点是各种螺旋型聚烯模型中的[1,7]-转移的过渡状态.

主要成果:

  • 对于几个螺旋状聚系统,确定了面间[1,7]-转移的激活障碍.
  • 发现和基层结构的存在会影响计算的障碍.
  • 预测[1,7]-shiftamer.com的激活屏障大约为14kcal/mol,显著低.

结论:

  • 在螺旋型聚烯中,表面间[1,7]-转移是可行的,障碍取决于形状.
  • 预先组织成螺旋形状是降低激活屏障的关键.
  • [1,7]-shiftamer代表了一个具有非常可访问的转移路径的模型系统.