Multiparameter Optimization with a Least-Squares Objective

Friedrich Maier October 19, 2017

Optimization is an efficient way to gain deeper knowledge of a model. Much like the different flowers in a colorful bouquet, you can perform a variety of different optimization projects using the Optimization Module. However, parameter estimation is also a widely used technique. Such an analysis is usually set as a least-squares problem based on measured data, but for a clear and unique answer, you might need multiple measurements. Today, learn how to estimate parameters using a multiparameter data set.

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Mats Danielsson October 11, 2017

The trebuchet is a large siege weapon that you might recognize from movies set in the Middle Ages or fantasy worlds. This weapon is built on the idea of converting potential energy into kinetic energy to hurl a projectile over a large distance. Simple as it seems, the trebuchet is a complicated dynamical system. In this blog post, we will build a simplified model of a counterweight trebuchet using the Multibody Dynamics Module and examine some of its design features.

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Edmund Dickinson October 10, 2017

In a previous blog post, we discussed why surfaces are special in chemical reactors. In this blog post, we’ll see how surface area is maximized in reactor structures such as pellet beds, and how we can simply and accurately simulate fixed-bed reactors in spite of their local geometric complexity and the importance of microscopic diffusion.

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Guest Linus Fagerberg October 3, 2017

Guest blogger Linus Fagerberg from Lightness by Design picks up where he left off in his previous blog post to discuss how radiated sound depends on the shell thickness of a muffler. Here, we discuss different entities for gauging the performance of mufflers. One important parameter is the thickness of the muffler’s casing and how this affects its performance. By performing acoustic-structure interaction simulations, we can see how shell thickness affects muffler performance.

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Andrew Young September 27, 2017

When simulating flow in porous media, it can be efficient to simplify the geometric complexity of the real porous material using a homogenized macroscale approach. But what if we don’t know what the effective macroscopic properties are? Here, we look at how to extract the macroscopic flow properties of porosity and permeability from a fully resolved microscale submodel.

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Hanna Gothäll September 20, 2017

Irregular shapes can come in several different formats. For example, we have previously discussed importing STL files and NASTRAN® meshes into the COMSOL Multiphysics® software. These formats are common when working with scanned biological data. In this blog series, we will look at different ways of handling irregular shapes in COMSOL Multiphysics.

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Uttam Pal September 19, 2017

In 1870, an audience watched as a stage was set with two buckets, one on top of the other. Due to a small hole in the upper bucket, water poured into the lower bucket, bending as it did so. To the audience’s amazement, sunlight followed the bend of water — a phenomenon later termed total internal reflection. The performer on stage, John Tyndall, was one of the many scientists who tried to control the most visible form of energy: light.

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Guest Linus Fagerberg September 14, 2017

Guest blogger Linus Fagerberg from Lightness by Design returns to share a novel approach for predicting external noise generation in muffler designs. In recent years, the European Union has introduced stricter noise emission limits for road vehicles. For those designing mufflers, these limits make it important to create more efficient ways of developing and assessing the performance of their designs. At Lightness by Design, we’ve developed a novel approach that accomplishes this goal.

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Phillip Oberdorfer September 6, 2017

When simulating heat transfer in fluids with forced convection, we can often neglect the influence of temperature variations on the flow field unless the requirements on accuracy are very high. Computing the flow field independently might substantially decrease the computational cost with a negligible impact on accuracy in the solution. In this blog post, we demonstrate the advantages of using a one-way coupling in the COMSOL Multiphysics® software with a nonisothermal flow example.

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Guest Thomas Clavet August 31, 2017

Today, guest blogger Thomas Clavet of EMC3 Consulting, a COMSOL Certified Consultant, discusses simulating phased array and geometrically focused probes. Ultrasound focusing is widely used in various industrial applications, such as nondestructive testing (NDT) and medical imaging. For clinical applications, high-intensity focused ultrasound (HIFU) is a specific aspect of this technology where most of the power provided by the probe is carried to a targeted zone to coagulate biological tissues. This blog post discusses ultrasound focusing simulation.

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Ruud Börger August 22, 2017

Have you ever feared a deadline because your model took longer to solve than expected? Here, we discuss common causes of time delays and how to prevent them. Let’s start with a real-world example: solving a complex modeling project on a deadline.

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