Studying Presbyopia with an Optomechanical Model of the Human Eye

Thomas Forrister October 24, 2018

During routine exams, eye care professionals look for common refractive errors like nearsightedness, farsightedness, and astigmatism. As patients age, doctors also look for presbyopia, a loss of the accommodative amplitude that results long-term in a complete loss of the near vision. The visual accommodation process is complex, and useful eye properties needed to improve diagnosis and presbyopia treatment are difficult to obtain. To address the problem of measuring the refractive index of the lens, researchers developed a reverse engineering technique […]

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Walter Frei October 22, 2018

One of the core strengths of the COMSOL Multiphysics® software is the ability to easily define loads and constraints that move over time. There are actually several different ways in which this can be done, all within the core functionality of the software. In today’s blog post, we will guide you through three of these approaches.

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Chien Liu October 18, 2018

The Schrödinger-Poisson Equation multiphysics interface simulates systems with quantum-confined charge carriers, such as quantum wells, wires, and dots. Here, we examine a benchmark model of a GaAs nanowire to demonstrate how to use this feature in the Semiconductor Module, an add-on product to the COMSOL Multiphysics® software.

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Lipeng Liu October 12, 2018

Using the Numeric Port feature, available in the COMSOL Multiphysics® software with the add-on RF Module, the mode of a port with an arbitrary shape can be computed numerically via a boundary mode analysis. By adding a Frequency Domain or an Adaptive Frequency Sweep study, the S-Parameter and Smith plots can be obtained. The numeric port also enables us to calculate the characteristic impedance of transmission lines operating in the transverse electromagnetic (TEM) mode.

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Jiyoun Munn September 25, 2018

When we analyze high-frequency electromagnetics problems using the finite element method (FEM), we often compute S-parameters in the frequency domain without reviewing the results in the complementary domain; that is, the time domain. The time domain is where we can find other useful information, such as time-domain reflectometry (TDR). In this blog post, we will demonstrate data conversion between two domains in order to efficiently obtain results in the desired computation domain through a fast Fourier transform (FFT) process.

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Thomas Forrister September 13, 2018

With the rise of 5G and other wireless millimeter-wave applications, there has been an increase in front-end antenna solutions that depend on monopole, dipole, and patch antennas. In these devices, the radiation efficiency tends to suffer due to the effect of lossy silicon substrate materials. Enter the dielectric resonator: Antennas using these resonators (made of nonmetallic materials) have a higher radiation efficiency. To increase directivity and gain at high frequencies, engineers can optimize dielectric resonator antenna (DRA) designs with simulation.

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Bridget Paulus September 10, 2018

Schottky diodes are one of the oldest semiconductor components, but they are still found in many modern applications, including computers and radar systems. To ensure that a Schottky diode performs well, it’s important for engineers to accurately analyze factors like current density and barrier height in the design. As a benchmark model demonstrates, the COMSOL Multiphysics® software and add-on Semiconductor Module are well suited for this type of analysis.

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Brianne Christopher August 14, 2018

If you ever visit the extravagant dome within St. Paul’s Cathedral in London, be careful what you say. As Lord Rayleigh discovered circa 1878, the vaulted structure exhibits an interesting acoustics phenomenon: Whispers from one part of the dome can be clearly heard in other areas. Rayleigh called the effect a “whispering gallery”. Surprisingly, you can observe a similar effect in another field of science entirely: light waves traveling in an optical ring resonator.

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Caty Fairclough August 9, 2018

Electrically erasable programmable read-only memory (EEPROM) is a type of nonvolatile memory that enables users to repeatedly store and erase small amounts of data by applying a voltage pulse. EEPROM is often used as a storage medium in computers and mobile devices and has applications in devices like microcontrollers. To analyze the designs of EEPROM devices, engineers can turn to semiconductor simulation.

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Caty Fairclough July 13, 2018

Circulators are a bit like traffic circles (also known as rotaries or roundabouts), where motion occurs in one direction only and each pathway doubles as an entrance and exit. In a circulator, however, the microwave signal always exits at the next available port. This characteristic makes circulators useful for applications that involve coupling transmitters and receivers to common antennas. To ensure that circulators function successfully, electrical engineers can study their designs with electromagnetics simulation.

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Brianne Christopher July 2, 2018

What do beer fermentation, soil analysis, and the production of dairy products have in common? They all involve the use of ion-sensitive field-effect transistors (ISFETs) for pH measurement. These sensors are small, efficient, and durable, which makes them suitable for food, environmental, and biomedical applications. However, ISFETs can experience drift and are sensitive to different temperatures, which limits their accuracy and stability. Using the COMSOL® software, engineers can accurately analyze ISFET designs and improve their performance.

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