A 100-year-old physics problem has been solved

In 1914, K. S. Johnson introduced the concept of Q factor. The length of time a signal can be stored in a resonator is inversely proportional to the bandwidth. A high Q resonator can store narrow band energy for a long period of time, a low Q resonator has a larger bandwidth but can store energy for

Grain size dependence of the twin length fraction in nanocrystalline Cu thin films via transmission electron microscopy based orientation mapping

Transmission electron microscopy (TEM) based orientation mapping has been used to measure the length fraction of coherent and incoherent Σ3 grain boundaries in a series of six nanocrystalline Cu thin films with thicknesses in the range of 26–111 nm and grain sizes from 51 to 315 nm. The films were annealed at the same temperature (600 °C) for the same length of time (30 min), have random texture, and vary only in grain size and film thickness. A strong grain size dependence of Σ3 (coherent and incoherent) and coherent Σ3 boundary fraction was observed. The experimental results are quantitatively compared with three physical models for the formation of annealing twins developed for microscale materials. The experimental results for the nanoscale Cu films are found to be in good agreement with the two microscale models that explain twin formation as a growth accident process.


Focused ion beam and scanning electron microscopy for 3D materials characterization

In this article, we review focused ion beam serial sectioning microscopy paired with analytical techniques, such as electron backscatter diffraction or x-ray energy-dispersive spectrometry, to study materials chemistry and structure in three dimensions. These three-dimensional microanalytical approaches have been greatly extended due to advances in software for both microscope control and data interpretation. Samples imaged with these techniques reveal structural features of materials that can be quantitatively characterized with rich chemical and crystallographic detail. We review these technological advances and the application areas that are benefitting. We also consider the challenges that remain for data collection, data processing, and visualization, which collectively limit the scale of these investigations. Further, we discuss recent innovations in quantitative analyses and numerical modeling that are being applied to microstructures illuminated by these techniques.


Microstructural Characterization of Hard Ceramics

This chapter reviews recent developments in the microstructural characterization of hard ceramics. It begins with a survey of the most important microstructural features that can be derived from characterization experiments. These include grain size, grain shape, contiguity, texture, grain boundary character distribution, and curvature. In each case, the parameters are illustrated by examples of data. The remainder of this chapter focuses on recent advances in three-dimensional microstructural characterization. Examples of progress in the areas of three-dimensional atom probe, electron and X-ray tomography, dual beam focused ion beam analysis, and X-ray diffraction microscopy are all discussed.


Formation of annealing twins during recrystallization and grain growth in 304L austenitic stainless steel

Understanding of the mechanisms of annealing twin formation is fundamental for grain boundary engineering. In this work, the formation of annealing twins in a 304L austenitic stainless steel is examined in relation to the thermo-mechanical history. The behaviour of annealing twins of various morphologies is analysed using an in-situ annealing device and EBSD. The results confirm that there is a synergistic effect of prior strain level on annealing twin density generated during recrystallization. The higher the prior strain level, the higher the velocity of grain boundary migration and the higher the annealing twin density in the recrystallized grains. This effect decreases as the recrystallization fraction increases. The existing mathematical models (Pande’s model and Gleiter’s model), which were established to predict annealing twin density in the grain growth regime, can not predict this phenomenon.


Auto Transformer Starting System for Induction Motor

Stern thruster motor’s main breaker located in MSB is tripping after start the motor,

we checked the insulation of motor and auto transformer, both are healthy.

we checked all contactor , its also good.

what is the reasons for tripping main breaker


Introducing Free DXF Files: Ready To Cut CNC Designs

free dxf filesThere’s a lot of fun to be had with decorative and artistic CNC projects.  Such projects don’t require a lot of precision and are option 2 to 2 1/2D, so they’re easy to make with a CNC Router, Laser, Waterjet, or Vinyl Cutter.  Sometimes we’re adding a design as a decorative element on top of…