Jove
Visualize
联系我们
JoVE
x logofacebook logolinkedin logoyoutube logo
关于 JoVE
概览领导团队博客JoVE 帮助中心
作者
出版流程编辑委员会范围与政策同行评审常见问题投稿
图书馆员
用户评价订阅访问资源图书馆顾问委员会常见问题
研究
JoVE JournalMethods CollectionsJoVE Encyclopedia of Experiments存档
教育
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab Manual教师资源中心教师网站
使用条款与条件
隐私政策
政策

相关概念视频

Effective Value of a Periodic Waveform01:07

Effective Value of a Periodic Waveform

470
The concept of effective value, the root mean square (RMS) value, is crucial in understanding electrical circuits and power delivery. This idea emerges from the necessity to measure the effectiveness of a voltage or current source in supplying power to a resistive load.
The effective value of a periodic current represents the direct current (DC) that conveys the same average power to a resistor as the periodic current itself. This concept is crucial when assessing AC circuits. To determine the...
470
Gradient and Del Operator01:14

Gradient and Del Operator

2.4K
In mathematics and physics, the gradient and del operator are fundamental concepts used to describe the behavior of functions and fields in space. The gradient is a mathematical operator that gives both the magnitude and direction of the maximum spatial rate of change. Consider a person standing on a mountain. The slope of the mountain at any given point is not defined unless it is quantified in a particular direction. For this reason, a "directional derivative" is defined, which is a vector...
2.4K
Linear Approximation in Time Domain01:21

Linear Approximation in Time Domain

59
Nonlinear systems often require sophisticated approaches for accurate modeling and analysis, with state-space representation being particularly effective. This method is especially useful for systems where variables and parameters vary with time or operating conditions, such as in a simple pendulum or a translational mechanical system with nonlinear springs.
For a simple pendulum with a mass evenly distributed along its length and the center of mass located at half the pendulum's length,...
59
Sampling Continuous Time Signal01:11

Sampling Continuous Time Signal

195
In signal processing, a continuous-time signal can be sampled using an impulse-train sampling technique, followed by the zero-order hold method. Impulse-train sampling involves the use of a periodic impulse train, which consists of a series of delta functions spaced at regular intervals determined by the sampling period. When a continuous-time signal is multiplied by this impulse train, it generates impulses with amplitudes corresponding to the signal's values at the sampling points.
In the...
195
Basic Discrete Time Signals01:16

Basic Discrete Time Signals

186
The unit step sequence is defined as 1 for zero and positive values of the integer n. This sequence can be graphically displayed using a set of eight sample points, showing a step function starting from n=0 and remaining constant thereafter.
The unit impulse or sample sequence is mathematically expressed as zero for all n values except at n=0, where it is one. The unit impulse sequence, denoted by δ(n), is the first difference of the unit step sequence, while the unit step sequence u(n) is...
186
Linear Approximation in Frequency Domain01:26

Linear Approximation in Frequency Domain

83
Linear systems are characterized by two main properties: superposition and homogeneity. Superposition allows the response to multiple inputs to be the sum of the responses to each individual input. Homogeneity ensures that scaling an input by a scalar results in the response being scaled by the same scalar.
In contrast, nonlinear systems do not inherently possess these properties. However, for small deviations around an operating point, a nonlinear system can often be approximated as linear....
83

您也可能阅读

相关文章

通过共同作者、期刊和引用图与本文相关的文章。

排序
Same author

Identification of the gene cluster for the dithiolopyrrolone antibiotic holomycin in Streptomyces clavuligerus.

Proceedings of the National Academy of Sciences of the United States of America·2010
Same author

Safety evaluation of tea (Camellia sinensis (L.) O. Kuntze) flower extract: assessment of mutagenicity, and acute and subchronic toxicity in rats.

Journal of ethnopharmacology·2010
Same author

Influences of soil properties and leaching on nickel toxicity to barley root elongation.

Ecotoxicology and environmental safety·2010
Same author

Effects of CO2 insufflation on cerebrum during endoscopic thyroidectomy in a porcine model.

Surgical endoscopy·2010
Same author

Plants' use of different nitrogen forms in response to crude oil contamination.

Environmental pollution (Barking, Essex : 1987)·2010
Same author

Overexpression of p35 in Min6 pancreatic beta cells induces a stressed neuron-like apoptosis.

Journal of the neurological sciences·2010

相关实验视频

Updated: May 24, 2025

Gradient Echo Quantum Memory in Warm Atomic Vapor
10:00

Gradient Echo Quantum Memory in Warm Atomic Vapor

Published on: November 11, 2013

12.8K

基于单个振荡波形的梯度延迟估计.

Bo Li1, Xiao Liang1, Manuel Taso2

  • 1Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, MD, United States.

Magnetic resonance imaging
|March 6, 2025
PubMed
概括
此摘要是机器生成的。

我们开发了一种使用单个振荡波形来估计梯度延迟的快速方法. 这种技术准确地纠正成像器件,提高MRI扫描质量.

关键词:
梯度延迟估计的估计.这是一种苏打水.单波形方法的方法螺旋螺旋的螺旋是一个螺旋.在pCASL中使用.

更多相关视频

Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques
09:01

Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques

Published on: April 4, 2017

8.6K
Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism
11:04

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Published on: September 1, 2014

11.1K

相关实验视频

Last Updated: May 24, 2025

Gradient Echo Quantum Memory in Warm Atomic Vapor
10:00

Gradient Echo Quantum Memory in Warm Atomic Vapor

Published on: November 11, 2013

12.8K
Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques
09:01

Gain-compensation Methodology for a Sinusoidal Scan of a Galvanometer Mirror in Proportional-Integral-Differential Control Using Pre-emphasis Techniques

Published on: April 4, 2017

8.6K
Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism
11:04

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Published on: September 1, 2014

11.1K

科学领域:

  • 磁共振成像 (MRI) 是一种磁共振成像技术.
  • 图像重建 图像的重建
  • 信号处理 信号处理

背景情况:

  • 梯度延迟是影响MRI图像质量的关键参数.
  • 准确估计梯度延迟对于高分辨率成像至关重要.
  • 现有的方法可能是耗时和复杂的.

研究的目的:

  • 通过使用单个振荡波形来估计梯度延迟的时间效率高的方法.
  • 引入基于单振荡波形的梯度延迟估计算法 (SODA).
  • 与参考方法相比,评估SODA的性能.

主要方法:

  • SODA通过测量连续时间点的相对回声转移来估计梯度延迟.
  • 一个三旋回声序在一次加速激发中获得所有梯度通道的测量.
  • 进行了模拟,幻影实验和体内研究.

主要成果:

  • 与基准方法相比,SODA在不同噪声水平的梯度延迟估计中没有显著差异.
  • 幻影实验证实了SODA和参考方法之间的强烈一致.
  • 梯度延迟校正 (GDC) 显著改善了图像质量,导致更清晰,更清晰的图像.

结论:

  • SODA提供了准确的梯度延迟估计与一个短的校准扫描时间.
  • 集成的三旋回声序便于测量梯度延迟和准确的螺旋轨迹.
  • SODA是螺旋MRI中梯度延迟校正的一个有价值的工具.