As you can probably guess from the title… I’ve been laid off from my mechanism controls position. My company had been doing layoffs for about 3 ½ years at this point so I lasted pretty long.

I’ve worked in the Aerospace industry for over 11 years now and there are some things I just don’t get.

“You can’t cut your way to growth”

During a down turn for a company they often times go into a serious cost cutting mode. Typically this means you pick up more of your health insurance, the cleaning crews stop coming, and the admins are no longer allow to provide napkins and plastic forks in little kitchenettes. Usually it also means layoffs, small raises and no promotions.

Obviously when the company is making less money it makes sense for that company to cut expenses. However, there’s an adage in business though – “You can’t cut your way to growth.” In other words you can’t just cut costs and expect to grow. Sure most companies are a little fat during good times so some targeted layoffs at the beginning of a downturn makes sense. But deep cuts in staffing don’t make sense from a long-term business standpoint.

Thoughts to consider when cutting staff

My premise is that a certain level of staff cutting is detrimental. And most people would probably respond with a “DUH!”

In my experience, in the Aerospace industry, most companies cut way too many people. Companies cut and cut and cut and cut and… Until they get profitable again. But the cutting rarely has anything to do with why the company (at least in the Aerospace industry) became profitable again. Typically the company has devoted a lot of resources to winning new sales and when it rains it pours. The company wins a big contract or a couple of them and now they don’t have the capacity to fill that contract without hiring. Now with each contract/sale won new people need to be hired.

New people require training and even when they walk into a job pretty much ready to go there are still processes and people to learn. Your older engineers, who are often in a position to define the direction and design of new products, are the only real exception. But the cost of hiring new people isn’t the only cost to be considered.

When companies cut too many people they lose capabilities. Those capabilities are lost both in the here and now and in the future. Not only are those capabilities lost but they have moved – most likely to a competitor. Along with the skills that those engineers have the company also loses all those half formed thoughts for new products or a better way to build or use an existing product.

Slow times are an opportunity – an opportunity usually squandered

In the Aerospace industry most of the products take years to develop. When times are good for the company is going gang-busters making what they promised to make. However, everyone is busy so who has the time to devote 10/20/30 hrs a week to a program that might fail? Ever work on one of those during busy times? I have and at best it seems you are ignored for your failure. At worst it harms your reputation within the company. Never mind that you put in lots of unpaid hours chasing a new product that is often someone else’s brain child – someone who doesn’t bother to stick around long enough to implement it.

Slow times at a company are an opportunity to improve processes, explore new technologies, and pursue more higher education. At my last employer I advocated using the slow time to allow senior engineers the opportunity to pursue their pet projects or more education while splitting their duties on current programs with junior engineers. That way the junior engineers can be brought further along and made more capable. The senior engineers can pursue projects that lead to future products. Everyone wins, the company has new products to sell, new capabilities to market, and the engineers’ career continues to move forward. The usual alternative is to give small or no raises and very few promotions. In this case, everyone loses it’s just a matter of degrees.

I’ve had a hard time identifying good industry rules of thumb for conservative controls design. So I’ve started a category on the wiki named “Rules of Thumb”.

These rules of thumb should provide inexperienced controls engineers with guidelines to a good design. For experienced engineers, I hope we will find these rules of thumbs to be informative about how other industries design their systems. We may even find that another industry’s common practices make sense for our own.

Please add whatever rules of thumb your industry uses.

Respect the Unstable

Back in August of 2003 I read an article in IEEE Control Systems Magazine titled “Respect the Unstable”, pp. 13-25, by Gunter Stein. The article made an immediate impression on me. The thrust of the article falls into what I call the “Controllers are Not Magic” category.

Most of the engineers I’ve worked with do not fully appreciate what controllers actually are. Nor do they fully understand what a controller can and cannot accomplish. So every so often I get requests for “Magic” in the form of “Don’t worry about Problem A, we can fix that with the controller.” Let me restate the obvious for anyone new to the controls field – Controllers are NOT Magic they manipulate physical systems and as such acquire the limitations of those systems.

The article by Dr. Stein provides an interpretation of the Bode Integrals as well as several examples of unstable systems.

The Bode Integrals

I’d put the equations here but I haven’t figured out how to do that in WordPress yet. So I’ve included a link the Bode Integrals on the wiki site here:
Bode Integrals in the Wiki

Here are my highlights from the article:

Basic Facts of Unstable Plants

Unstable systems are fundamentally, and quantifiably, more difficult to control than stable ones.

Controllers for unstable systems are operationally critical.

Closed-loop systems with unstable components are only locally stable.

and

The first integral applies to stable plants and the second to unstable plants. They are valid for every stablizing controller, assuming only that both plant and controller have finite bandwidths. In words, the integrals state that the log of the magnitude of sensitivity functionof a SISO feedback system, integrated over frequency, is constant. The constant is zero for stable plants, and it is positive for unstable ones. It becomes larger as the number of unstable poles increases and/or as the poles move farther into the right-half plane. (Technically, we must count all unstable poles here, including those in the compensator, if any.)

This is the equivalent of a conservation of energy for systems under control. The result being that to make a system less sensitive to disturbances in one frequency range the controlled system must become more sensitive in another frequency range (or all other frequency ranges).

In my current position we are often designing controllers to have good disturbance rejection at low frequencies while shooting for a minimum of peaking. The Bode Integrals make it obvious that low frequency disturbance rejection means more peaking in the higher frequencies. Sometimes the largest magnitude of the peaking can be reduced but that just means the peaking gets spread out in frequency. This observation of the Bode Integrals informs us of the limitations of controllers – we can’t have it all. So we now realize that our controller design is largely a matter of choosing the shape of our frequency response very carefully.

Sensor Models

Given that sensors are vital to feedback systems I’ve included a bunch of sensor models.  You can see the New Sensor Models by clicking the link.

I’ll be adding more in the future as i get the time.

Source:  http://cr4.globalspec.com/thread/29317#newcomments

Hello Members,

Please go through this BBC story of the Chinese built/launched communications satallite for the Nigerian government. Here http://newsvote.bbc.co.uk/2/hi/africa/7726951.stm

The satellite was launched about two years ago and it is confirmed packed up.

Apart from the indicated power problem, what could be other causes of the satellite failure?

Cheers,

ethobil

Observations

The BBC article stated that the Nigerian satellite

1. … was limited because the type of frequency it used was disturbed by clouds in the atmosphere, and did not work properly in Nigeria’s rainy season or during the Harmattan, when clouds of dust blow down from the Sahara, he said.
2. … also operated on frequencies already allocated to other companies and interfered with other providers’ equipment.
3. … controllers shut the satellite down because it was having problems with its power supply, the government announced.

The observations in #1 and #2 are items that I learned to look out for before I graduated with my Bachelors.

Background for Observation #2:  Operating a satellite on another satellite’s frequency is both extraordinarily rude and stupid.  Interference from the satellite assigned that frequency will make both satellites useless for significant portions of their design life.  Obviously this is to be avoided and there are agencies to regulate these frequencies.

Background for Observation #1:  This is amatuer hour stuff.  Anyone with satellite TV or satellite radio knows that weather interferes with transmissions.  The thing is, the impact of weather can be minimized if not eliminated if you pick the correct frequency.

You may be asking why I addressed #2 first and then #1.  The answer is this, Observaton #2 shows that the Nigerians didn’t do even the most basic homework and contact the proper authorities.  Observation #1 reinforces this notion through an ignorance of basic satellite operations and limitations.

Observations #1 & #2 demonstrate that on the Nigerian customer (at least those in charge) didn’t know the first thing about what they were buying.  Questions about operations, lifetime, and weather are pretty basic and I learned to ask those questions before graduating with my Bachelors.

The final Observation

Observation #3 is that the satellite was shut down for power problems.  This could be something like a battery failure, power subsystem failure, solar array failure, or ADCS failure (which could point the arrays or the whole satellite the wrong way).

Given that the Nigerians didn’t do their homework – to know which frequency to use for their communications satellite, nor did they do enough homework to contact the correct regulatory agencies – before buying an expensive piece of hardware it only makes sense that they didn’t do their homework regarding system testing.

My guess is that the Chinese bid cheap re-using a satellite they designed for someone else.  This is common practice to reduce cost and risk.  But there are always custom changes when requirements change or new, updated hardware is added to the design.  If you don’t test the integrated system properly the chances of failure are high.  The Nigerian satellite was probably a recycled telecom satellite from another customer and some component of power system (like bateries) or the ADCS system (like attitude sensors or thrusters) was replaced.

An example of what I’m thinking…

An ADCS sensor, lets use a gyro for now, is replaced.  The new sensor comes from the same manufactuerer with the same power, size, and mounting requirements.  However, this new sensor provides its output in a different coordinate system such that 2 of the 3 axes (X & Y) are identical to the previous sensor but the 3rd axis (Z) is -1 of the original.  Without thorough design effort and proper integrated system testing, this -1 is easy to miss.  Then the whole satellite ends up pointed away from the sun and runs out of power.

The Nigerians missed the easy stuff, why would we assume they got the hard stuff, like proper testing, correct?

What finally worked

I have a quad core machine at my desk so I run multiple MATLAB windows.  These multiple windows allowed me to test some distributed computing processes.  As a result I set up a script for allowing the multiple windows to run.  I was using Stateflow in the model which requires a compile before each run.  As a result the model had to be run from a temporary directory.

This temporary directory was the first sign that the function, when distributed, is working.  The second sign was when the output file is saved.

Long story short, the batch command worked.  The batch command works but only with the PathDependencies and FileDependencies properties set.  The function is something like this

jj = batch(‘monte_sim_loop’, ‘matlabpool’, 0, ‘PathDependencies’, {…}, ‘FileDependencies’, {…});

The matlabpool set to 0 is important.  I tried to using a matlabpool of 3 for my initial runs.  It tied up 4 nodes but only run 1 instance of the sim.  Then I created a loop

for ii = 1:15

  jj = batch(…

end

The reason that a matlabpool of 3 tied up 4 nodes was that the matlabpool property is for how many additional nodes you want running.  It originally appeared to be an overhead function that was created.  A coworker discovered the matlabpool command already assumes 1 node and so anything higher than 0 ties up that many extra PCs for the 1 job task.  Since I just want my jobs distributed (not parallel) I set the property to 0.   When I ran the loop above, 15 computers were tied up and 15 nodes worth of results were produced.

If you know more, please share

I invite anyone and everyone who knows more about how to use the Parallel Computing Toolbox to share.  Use the comments to share.  Or if you like I welcome guest bloggers.

Thanks

Previous, related, posting

MATLAB’s Parallel Computing Toolbox First Impression

No one cares about nuclear power once it’s in space.  Only on it’s way to space.

Radioactive Contamination

Nuclear power in space comes from an RTG (Radioisotope Thermoelectric Generator).  The RTG is powered by a radioactive isotope.  The isotope decays and produces heat in its decay.  That heat produces electricity through the use of thermocouples.

For space harware, the main threat from an RTG is that explosive destruction of the hardware containing the radioactive material would spread radioactive material.  The RTG containers are designed to survive this type of event so the odds of contamination are small.

What happens when the container is destroyed…

If the container were to break up the estimated odds of contamination are 1 in 10.  The alpha radiation that the most common RTG fuel cannot penetrate the skin but if it were inhaled it would do serious damage to internal organs.

There were protests when Cassini launched…

People were scared that if the Cassini launch failed then the radioactive fuel would find its way into the atmosphere and people would inhale it.  While this shouldn’t be taken lightly the launches are generally conducted over the ocean.  The winds in the atmosphere may disperse the radioactive material.

Obviously if the launch vehicle travels through all of the atmosphere it is unlikely that we can wait for a launch window where all of the prevailing winds are blowing out to sea.  This dispersion shouldn’t be taken lightly but understand that the fuel most US satellites use is only a problem when inhaled or ingested.  If the particles fall in the sea or on the land then it poses no threat – to people.

Basics of an RTG

An RTG is a Radioisotope Thermoelectric Generator.  Essentially these radioactive isotopes decay to more stable atoms.  As the isotopes decay they give off heat and that heat is converted to electricity.  The conversion to electricity is done using thermocouples.

An RTG is used on space craft instead of solar panels when the mission is very long or to an outer planet where the light energy provided by the sun is too weak (low density).  The Voyager and Cassini missions used RTGs.

Benefits of an RTG

For space the benfits of an RTG are obvious.

1. Long term power (in the range of hundreds of watts)
2. No moving parts – like solar arrays that have open up after launch
3. Degradation of output power happens but much slower than with solar panels

These advantages lead to a stable power source capable of operating for decades in extreme environments.

Fuel Source

From Wikipedia:

Plutonium-238, curium-244 and strontium-90 are the most often cited candidate isotopes, but other isotopes such as polonium-210, promethium-147, caesium-137, cerium-144, ruthenium-106, cobalt-60, curium-242and thulium isotopes have also been studied. Of the above, ²³⁸Pu has the lowest shielding requirements and longest half-life. Only three candidate isotopes meet the last criterion (not all are listed above) and need less than 25 mm of lead shielding to control unwanted radiation. ²³⁸Pu (the best of these three) needs less than 2.5 mm, and in many cases no shielding is needed in a ²³⁸Pu RTG, as the casing itself is adequate.

²³⁸Pu has become the most widely used fuel for RTGs, in the form of plutonium(IV) oxide (PuO₂). ²³⁸Pu has a half-life of 87.7 years, reasonable energy density and exceptionally low gamma and neutron radiation levels.

The criteria leading these choices of fuels are

1. Must have a half-life short enough that its decay produces substantial heat
2. Must ahve a half-life long enough that the heat generated is relatively stable for decades
3. For space, the energy output per density must be high
4. The radiation produced should be high energy with low penetration – preferably alpha-radiation – so that shielding can be minimal

Next post: Why people are scared.

This time Phoenix stays dead…

Where the Phoenix lander is on Mars it’s winter.  Phoenix ran out of power recently.  The 2 rovers, Spirit and Opportunity, have to fight for their own survival every Martian winter.  Why?  Because they use solar arrays.  Solar arrays that degrade with time.  Solar arrays that degrade with the deposition of dust.  Solar arrays that don’t produce much power when the Sun isn’t very high in the sky.

Power constraints have hampered interplanetary probes in the past.  The problem is that once a probe gets out near Jupiter there just isn’t enough sun light to do much.  Even large arrays can’t entirely overcome the problem of “not enough light”.

We have $100 million missions that end because of power

We have missions to Mars and Jupiter and beyond.  Some like Cassini use nuclear power.  Others use solar power.  Some missions, like Phoenix, have ended not because of mechanical failure, communications failure, or a lack of good science that still needs doing but because they have too little power.

A lack of power has not stopped the Voyager missions decades after their launch.  A lack of power doesn’t need to kill or maim anymore Mars missions.  A Radioisotope Thermoelectric Generator (RTG) is the answer.

Next post: What is an RTG?

Next Next post: Why people are scared.

Brain Drain

For decades now the US has been the place for the best and brightest from other countries to study.  I sizable chunk decide to stay especially in engineering.  As a result when various companies and the US gov decided they needed more engineers they simply imported them.

God forbid we

1. actually pay and treat engineers like they are professionals
2. give them something to do other than shuffle paper work and dodge management

And yet some people still lamented the lack of native born engineers graduating from our schools.  Some were so blind as to wonder why so few were graduating.

Well it’s time to start paying the bill…

India’s Space Program

A large chunk of our imported engineers come from India.  Often they come here because opportunities are limited in India for people born to the wrong caste.  So the people that can get to the US come over, study engineering, and stay.  But it is harder and harder for them to get jobs in Aerospace since most of the Aerospace companies have chosen to pursue defense work.

Now India has started its own space program while the US program slowly decays.  A number of those Indian engineers that stayed here are asking if there are jobs in their home country working on the space program.

The economy in the US is tanking making jobs harder to come by.  The US space program and surrounding Aerospace industry is less welcoming than it used to be.  And many would like to go home if they can find good job opportunities.

Reverse Brain Drain

The emerging space programs of China and India are a serious threat to the US technological superiority.  It may be years before the programs show a string of years with real funding and enthusiasm at home.  However, once those programs are established a much larger percentage of those foreign born engineers that come here to study will go back home when they are finished.

We will have fewer engineers in the coming years.  Without something inspirational to bring native US kids back into engineering it will only get worse.  I’ve complained about the pay and nature of the business where companies lay off large numbers of people every time their sales hiccup for a quarter but that’s not really the problem.

We can’t keep expecting to drain the brains of India and China

The problem is a lack of inspiration and vision.  As India and China demonstrate space programs that are a point of national pride they will become a more and more appealing career prospect.   As such it will become harder and harder to keep young foreign born engineers from going back to their country of origin.  However, the US lacks any serious goal for aspiring engineers to tackle.

There are inspirations out there, just no one with vision AND money

I’m a fan of space exploration and I think serious exploration – not just toy cars on Mars – would inspire.  But so would serious nano-tech, artificial intelligence, robotics (like Honda’s Asimo), alternative energy, and several other fields.

Instead we have risk averse companies who have reduced their R&D to incremental improvement shops.  The gov is just as risk averse and every satellite/R&D program is just 1 baby step better than the last.  In Aerospace the holy grail is propulsion.  In propulsion we’ve barely invented the wheel let alone an automobile.  Until the X-Prize was won almost no company spent any money on even incrementally better propulsion.  Even today the total dollar amount is a pittance.

If we want to continue to lead the world in technology (and by extension the world economy) then we need to get serious.  We need to choose 1 or 2 major project that can change everything – like alternative energy, Sci-Fi style propulsion, etc.  We need to get serious about real basic scientific research and serious engineering R&D.  You don’t make great leaps forward with risk averse baby steps.

Thankfully there’s at least DARPA, if only we could get about 1000 more of those going…

Here’s the article that inspired this rant:

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