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Related Concept Videos

Linear Approximation in Time Domain01:21

Linear Approximation in Time Domain

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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,...
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Time-Domain Interpretation of PD Control01:07

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Proportional-Derivative (PD) control is a widely used control method in various engineering systems to enhance stability and performance. In a system with only proportional control, common issues include high maximum overshoot and oscillation, observed in both the error signal and its rate of change. This behavior can be divided into three distinct phases: initial overshoot, subsequent undershoot, and gradual stabilization.
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Time and frequency -Domain Interpretation of PI Control01:27

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Proportional-Integral (PI) controllers are essential in many control systems to improve stability and performance. They are commonly used in everyday devices like thermostats to enhance system damping and reduce steady-state error. When the zero in the controller's transfer function is optimally placed, the system benefits significantly in terms of stability and accuracy.
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Time and frequency -Domain Interpretation of Phase-lead Control01:24

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Phase-lead controllers are commonly used in various control systems to enhance response speed and stability. Adjusting the brightness on a television screen offers a practical example of phase-lead control. When contrast is enhanced, a phase-lead controller is employed. Mathematically, phase-lead control is identified when the first parameter is smaller than the second.
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Time and frequency -Domain Interpretation of Phase-lag Control01:21

Time and frequency -Domain Interpretation of Phase-lag Control

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Phase-lag controllers are widely used in control systems to improve stability and reduce steady-state errors. A dimmer switch controlling the brightness of a light bulb serves as a practical example of phase-lag control, gradually adjusting the bulb's brightness. Mathematically, phase-lag control or low-pass filtering is represented when the factor 'a' is less than 1.
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Protein domains are small structurally independent units that are part of a single amino acid chain.  Although these domains are often structurally independent, they may rely on synergistic effects to perform their functions as part of a larger protein. Protein domains may be conserved within the same organism, as well as across different organisms.
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Related Experiment Video

Updated: Feb 13, 2026

Terahertz Microfluidic Sensing Using a Parallel-plate Waveguide Sensor
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High-pressure cell for terahertz time-domain spectroscopy.

Wei Zhang, Daniel Nickel, Daniel Mittleman

    Optics Express
    |March 10, 2018
    PubMed
    Summary

    We developed a novel sample cell for terahertz time-domain spectroscopy (THz-TDS) enabling low-frequency measurements. This allows detailed analysis of material phase diagrams under varying temperature and pressure conditions.

    Area of Science:

    • Condensed Matter Physics
    • Spectroscopy
    • Materials Science

    Background:

    • Traditional far-infrared spectroscopy using diamond anvil cells has limitations in low-frequency measurements.
    • Understanding material properties under extreme conditions (pressure, temperature) is crucial for various scientific fields.

    Purpose of the Study:

    • To introduce a new sample cell for pressure-dependent terahertz time-domain spectroscopy (THz-TDS).
    • To enable measurements at significantly lower frequencies than previously possible.
    • To facilitate the mapping of material phase diagrams and spectral changes under variable temperature and pressure.

    Main Methods:

    • Development of a novel sample cell with a larger aperture for THz-TDS.
    • Conducting pressure-dependent THz-TDS measurements across a wide range of frequencies (down to 3.3 cm-1).

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  • Varying temperature from 100 to 473 K and pressure up to 34.4 MPa.

    • Main Results:

    • The new sample cell allows terahertz spectroscopy measurements down to 0.1 THz (3.3 cm-1).
    • Demonstrated mapping of material phase diagrams by analyzing THz spectra.
    • Successfully tracked spectral changes within single phases as a function of temperature and pressure using nitrogen and R-camphor as examples.

    Conclusions:

    • The developed sample cell significantly expands the accessible frequency range for terahertz spectroscopy.
    • This technique provides a powerful tool for investigating material behavior under diverse temperature and pressure conditions.
    • Enables detailed characterization of phase transitions and spectral evolution in condensed matter.