It's Never Been Like This Before

Every so often I'll get in a conversation with someone about our droughts here in the mountains of California. The snow pack in the Sierra Nevada mountains is the major source of fresh water in the state so knowledge about it is vital. Fortunately there is data to be had that I can use to inform myself. I get the snow pack data for the two watersheds I am interested in from the California Data Exchange Center.

I update my files every year at the end of the snow season. This is usually April 1st. It's always surprising to me when people talk about the Sierra snowpack from news reports they hear or see, but don't actually look at the numbers. In fact some of the things I hear from people is so far from what the data implies it's troubling. Let me be clear from the outset, this is not about the overall water situation in California. It is about the two watersheds that directly impact my life. They are the Kern River Watershed and the Owens River Watershed.

Seki-Joju Bonsai and The End of The Season

I've finished up most of my horticultural work for the year and soon it will be time for the plant world to rest for the winter. We don't have much of a fall here but when winter descends it comes fast and with a vengeance. I planted my newest bonsai in its pot and it seems to be thriving. I have it wired for training and the root system is strong.

Seki-Joju Style Bonsai.

Down The Rabbit Hole

Charles Dodgson who wrote the wonderful book Alice's Adventures in Wonderland under the pen name Lewis Carroll was a mathematician by training and practice. His book was admirably illustrated by Sir John Tenniel. Dodgson  made some good strides in mathematical logic, linear algebra, and matrix operations. Of course, who doesn't remember who Alice spotted one fine day and decided to follow. 

 

Our notorious white rabbit, and so down his rabbit hole we go to do some exploring. Namely data, mathematics, curve fitting, and models,  all of which would be familiar territory for Dodgson. I was planning to post on a completely different matter when I realized I have been remiss, and that I needed to better define some things. 

SIR Model Revisited

I've gone back and cleaned up my basic SIR Model as described in a previous post. I have added some features and put some more thought into it. I hope to describe it here and what might be some of the ramifications. Given the current state of political affairs here in the United States and being the election season it has helped me wade through some of the effluvia that is always present in politics. Especially concerning this matter.

Properties of Explosives and Their Application Part 2

From the first post in this series I wrote about determining the performance of an explosive using the Cylinder Expansion test, or Cylex as it's commonly known. As I mentioned the radial velocity of an expanding cylinder (copper for the cylex test) is measured. This is done a number of different ways. The earliest method used a streak camera.

Properties of Explosives and Their Application Part 1

This is the first part of a series on the properties and application of explosive materials. I suppose the first thing to do is define some terms. An explosive is any system, gas, liquid, or solid, that will propagate a supersonic wave front at a characteristic velocity that is supported by chemical reaction. A graphical relationship helps to show this.

One of the first aspects of explosive performance is the ability of the reacted material to move metal.  The Gurney Equations describe this well. R.W. Gurney did much of his initial work in Quantum Mechanics but later moved to the United States and was very productive in the field of metal motion due to gas dynamics from explosions. Gurney's equations could be considered near universal for many explosive systems. A copy of his original document is here in the Open PDF section of my Google Drive.

Introduction to Explosive Materials

Much of my work over the years involved testing and developing explosive systems. What I hope to do with this series of posts is to describe in a succinct form some of the background, both theoretical and experimental, that went into my work. This series of posts is an overview of explosive materials and their uses. It's similar to some texts available but I will be including links and various downloadable items that some readers might find useful.

There are three basic types of explosive materials: primaries like azides and fulminates; secondaries such as HMX, RDX, and TNT; commercial, which include variants of ammonium nitrate/fuel oil used in the mining industry.