unconventional magnetic recording

Given the previous posts on magnetic recording, we are now in the position to look at unconventional magnetic recording. In other words, instead of applying a write field of sufficient strength to switch magnetic grains, we look at other ways to switch a magnetic grain. This has become to be known as “energy assist magnetic recording”. In future recording systems this will be required since there is a limit on the applied field one can produce in a small area....

on modeling infection

Compartmental models are often used to simplify the mathematical modeling of infectious disease. The population is split into compartments and it is assumed each individual in a compartment has the same characteristics. While this may appear to be rather crude, such models have shown to accurately model previous infectious outbreaks[1]....

signals from magnetic medium

Recently we had an interesting problem posed to us. The more general problem is detecting magnetization on a granular medium. Such questions are relevant for magnetic recording, e.g. tape, hard disk drives, etc....

Runge-Kutta in Swift

Apple’s Scene Kit has a built in physics engine. However, we discovered it wasn’t accurate for particular cases. We decided to replace the physics engine with a Runge-Kutta method. ...

light-weight way to capture results from cloud HPC/HTC

For large HTC (or HPC) computations on the cloud, ‘spot instances’ (AWS-speak), ‘low-priority VM’ (Azure-speak) or ‘preemptible VM instances’ (GoogleCloud-speak) are the low cost options for compute. Of course, the challenge here is that these instances/VM can vanish at anytime. If you’re doing a large HTC task, you want to make sure you save your result (and/or checkpoint) files as soon as they are generated to persistent storage. Otherwise you lost the computation you just paid for....

persistent storage

On-premise computing cluster usually have RAID for persistent storage and a robust backup solution. Storage in the cloud costs $. ...

macOS automation

In a vain attempt* to get Desktop Icon Manager (DIM) into the Mac App Store, we wrote a class that simply ‘hides’ or ‘reveals’ the Desktop icons with a notification. Quite useful when giving presentations (alas, our Desktops are usually ‘messy’ with current work)....