## Friday, December 27, 2013

### DoD Unmanned Systems Roadmap 2013

The FAA isn't the only one "roadmapping". The US Department of Defense recently released a road map for unmanned systems.
Strategy and budget realities are two aspects of the Defense Department’s new Unmanned Systems Integrated Roadmap, released today. The report to Congress is an attempt to chart how unmanned systems fit into the defense of the nation. “The 2013 Unmanned Systems Integrated Roadmap articulates a vision and strategy for the continued development, production, test, training, operation and sustainment of unmanned systems technology across DOD,” said Dyke Weatherington, the director of the unmanned warfare and intelligence, surveillance and reconnaissance office at the Pentagon. “This road map establishes a technological vision for the next 25 years and outlines the actions and technologies for DOD and industry to pursue to intelligently and affordably align with this vision,” he continued.

The funding profile is interesting. The roadmap mentions a reduction in funding for unmanned systems over the next five years. One of the results in Ehrhard's study of UAV development is that funding for these systems tends to dip in the interwar periods relative to manned systems.

## Thursday, December 12, 2013

### EELV Competition Legislation

The NDAA is being done a bit differently this year.
This legislation is substantially based on two bills: (1) HR. 1960, the National Defense Authorization Act for FY14 which passed the House on June 14, 2013 by a vote of 315-108; and (2) S.1197, a product of the Senate Armed Services Committee which passed out of committee on the same day by a vote of 23-3.

Because passing this legislation before the end of the calendar year is vital, these two products were merged through a series of negotiations at all levels of the House and Senate. Negotiators also considered, and in many cases included, a number of proposals offered by members of both parties that were intended for consideration by the full Senate. This legislation represents a broad bi-partisan consensus about America’s national security goals, resources, and policies.
The text of the "pre-conferenced" bill is available on the House Armed Services Committee site.

One of the interesting portions is Section 145: Competition for Evolved Expendable Launch Vehicle Providers.
The Secretary of the Air Force shall develop a plan to implement the new acquisition strategy for the evolved expendable launch vehicle program described in the acquisition decision memorandum dated November 27, 2012.
The acquisition decision memorandum mentioned in the law is described in this article. The plan is supposed to include:
• proposed cost, schedule and performance
• mission assurance activities
• manner in which the contractor will operate under the Federal Acquisition Regulations
• the effect of other contracts in which the contractor is entered into with the Federal Government, including the evolved expendable launch vehicle launch capability contract, the space station commercial resupply services contracts, and other relevant contracts regarding national security space and strategic programs
That last portion is most interesting to me. What are the effects of the CRS contract, and the infrastructure subsidy contract on competition for EELV-class launches?

## Wednesday, December 11, 2013

### GE Jet Engine Bracket Challenge Winners

 Topologically Optimized Bracket by KMWE + TU Delft
The winners for the GrabCAD GE Bracket Design challenge have been manufactured and tested. See all the pictures here. The team I mentioned previously that was using topology optimization went ahead and manufactured their bracket themselves. What a great demonstration of metal additive manufacturing (3d printing) and topology optimization. I hope the GrabCAD folks get the promised detailed feedback for all the entries up soon.

## Wednesday, November 13, 2013

### FAA Releases UAS Integration Roadmap

From the press release:
WASHINGTON –The U.S. Department of Transportation’s Federal Aviation Administration (FAA) today released its first annual Roadmap outlining efforts needed to safely integrate unmanned aircraft systems (UAS) into the nation’s airspace. The Roadmap addresses current and future policies, regulations, technologies and procedures that will be required as demand moves the country from today’s limited accommodation of UAS operations to the extensive integration of UAS into the NextGen aviation system in the future.
By way of AUVSI. The Roadmap and Comprehensive Plan are both available to download from the FAA site.

## Saturday, November 2, 2013

### LockMart SR-72

 NASA SP-2001-4525
AvWeek has a nice marketing piece for Lockheed-Martin's Mach 6 ISR/strike concept based on Blackswift that they're calling SR-72. They have a nice set of graphics that compares the the new Mach 6-capable combined cycle engine to the old Mach 3 SR-71 cycle.

 YF-12 Inlet Schematic
The SR-71 provides a nice historical example of design for high-temperature metallic structures. There is also a great deal of detail on the research NASA did on the YF-12 which includes quite a bit of declassified material on how the YF-12 family managed the inlet boundary layer and shock train across the wide range of Mach numbers at which it operated. One of the aircraft involved in that research program is at the museum so folks can go see it, and there is a virtual tour of the SR-71 cockpit available for those who can't make it to Dayton.

## Friday, November 1, 2013

### Free (not Libre) TopOpt App

This little app from the TopOpt research group at the Technical University of Denmark is lots of fun to play with. Versions available:
You can move around boundary conditions and forces to see what 2-D arrangement of material is the stiffest. There is also an option to export the geometry to an stl file for 3-D printing.

I couldn't find links to any source for this implementation, but it is based on the methods in the 99- and 88-line codes I've written about previously.

## Tuesday, October 29, 2013

### Defense Acquisitions: Where Should Reform Aim Next?

An alternative title for this GAO report might be, "Defense Acquisitions: Constantly Reforming." We've been "reforming" for decades with such little variation in results that "Acquisition Reform" has become nearly impossible to take seriously:

Let's just skip the acquisition reform charade... Another blue-ribbon study, more legislation and a new slogan will not make it happen at last...
Prof. H. Sapolsky, MIT

Luckily, this latest GAO report on the problem has no sweeping "blue ribbon"-style reform suggestions. There seems to be a pretty pragmatic recognition that perverse incentives are largely the reason that many of the grandiose reform efforts of the past were doomed to failure:
Reforms that focus on the methodological procedures of the acquisition process are only partial remedies because they do not address incentives to deviate from sound practices. Weapons acquisition is a complicated enterprise, complete with unintended incentives that encourage moving programs forward by delaying testing and employing other problematic practices. These incentives stem from several factors. For example, the different participants in the acquisition process impose conflicting demands on weapon programs so that their purpose transcends just filling voids in military capability. Also, the budget process forces funding decisions to be made well in advance of program decisions, which encourages undue optimism about program risks and costs. Finally, DOD program managers' short tenures and limitations in experience and training can foster a short-term focus and put them at a disadvantage with their industry counterparts.

Drawing on its extensive body of work in weapon systems acquisition, GAO sees several areas of focus regarding where to go from here:
• at the start of new programs, using funding decisions to reinforce desirable principles such as well-informed acquisition strategies;
• identifying significant risks up front and resourcing them;
• exploring ways to align budget decisions and program decisions more closely; and
• attracting, training, and retaining acquisition staff and managers so that they are both empowered and accountable for program outcomes.
These areas are not intended to be all-encompassing, but rather, practical places to start the hard work of realigning incentives with desired results.

## Monday, October 28, 2013

### Open Source Aeronautical Engineering Tools

* permanent page with updates: Open Source Aeronautical Engineering Tools*

I was reading through some of the papers and cites related to OpenMDAO and stumbled across a couple interesting papers[12] on open source software in aeronautics.
Abstract: Open source software has become an alternative to commercial software for industrial users. Industrial users adopting to OSS and the underlying concepts need to consider changing their software development practices and organization in order to benefit from the OSS model. These changes may involve both technical and non-technical aspects. Openness and collaboration with a community are two non-technical concepts that may require such changes, while evaluating OSS products or evaluating different strategies for integrating OSS products are two technical aspects that may require adoption.
The objective of this paper is to create an awareness for the adoption of OSS in an industrial context. OSS can be used in different ways. Four categories of using OSS are presented by discussing motivation, implication and experience for each category. The main conclusion from this work is that organizations should have a realistic expectation of both the designated benefits and extension of organizational changes necessary to adopt to OSS. This conclusion is based on observations from industrial organizations using OSS, including OSS in the aeronautics industry, as well as from observations reported in the literature on open source.

## Friday, October 25, 2013

### BG CFD Group at TU Berlin Youtube Channel

Some great visualizations of detached eddy simulations around cylinders, airfoils and cascades on the youtube channel for BG CFD group at TU Berlin.

## Thursday, October 24, 2013

### Funding for US Government Launch-Related Activities

As part of a broader effort looking at impediments to launch services procurement, the GAO summarized US government-wide budget requests for space launch-related activities (pdf). The purpose of the GAO's broader effort is to provide short- and long-term assessments examining impediments to economical procurement of government launch vehicles and launch services across government.

GAO reviewed FY14 through FY18 space launch-related President's Budget (then year dollars) request by NASA, NOAA, and DOD including military services and other offices.
 FY14 FY15 FY16 FY17 FY18 Total (then-year $M) Procurement 4981.4 5819.7 5816.2 5914.4 5915.5 28447.2 RDT&E 2469.0 2473.0 2414.6 2073.9 1834.0 11264.5 Other 1053.5 774.3 770.7 790.0 762.5 4151.0 Total 8503.9 9067.0 9001.5 8778.3 8512.0 43862.7 Total funding seems pretty flat accross the five years examined. Both DOD and NASA are acquiring launch vehicles by launch services contracts. Procurement is about evenly split between DOD and NASA (slightly more by DOD). The bulk of RDT&E dollars are spent by NASA:$10.5 billion over the five years vs. $718 million. On the slide detailing the RDT&E spending this report cites another GAO report about the FY10 National Defense Authorization Act requirement for the Department of Defense and the Director of National Intelligence to issue a space science and technology strategy every 2 years. GAO recommends DOD coordinate more with NASA and NOAA to leverage their significant RDT&E investment. I am interested to see what "impediments" GAO finds as a result of their broader effort. ## Wednesday, October 23, 2013 ### Starcraft, Jaynes, and Bayesian UQ Interesting content covered on Nuite Blanche of a recent Paris Machine Learning meetup. The work on applying Bayesian Programming and Learning for Multi-Player Video Games was really neat. It's about developing a bot for playing Starcraft. Some additional related presentations: This problem is real enough to be interesting, and simple enough to tackle. I really liked how this work dealt with the separation of strategic/tactical level decision making. ## Tuesday, October 22, 2013 ### 11th World Congress on Computational Mechanics (WCCM XI) The 11th World Congress on Computational Mechanics (WCCM XI) is coming up in July in Barcelona. Dates: abstracts due 29 Nov 2013, and full papers due 28 Feb 2014. The deadline for mini-symposium proposals has passed. There are some interesting looking ones (ECCM, ECFD), ## Monday, October 21, 2013 ### BRLCAD: Archer Alpha Archer is an interface update to the graphical geometry editor for BRLCAD. The BRLCAD developers have done a significant refactoring of the code for this release: A lot of work has gone into refactoring and restructuring MGED code into library form so that we could develop new interfaces on top without losing functionality. We now have a newly developed GED "geometry editing" library that contains the majority of our commands in reusable form. Archer was built on top of GED and the interface has been significantly extended. It is nice having everything in one window. There's a tree view for the shapes, regions, and combinations in the database on the left, a command window at the bottom, and the main visualization window in the middle. ## Saturday, October 19, 2013 ### Drone Swarm Photogrammetry of the Matterhorn senseFly mapped the Matterhorn with a bunch of little UAVs. Pretty impressive photogrammetric point cloud: 300 million points! ## Friday, October 18, 2013 ### Commercial Model Aircraft Use  22nd IMR Meshing Contest Model There are some interesting commercial uses of model aircraft listed in Pirker's motion to dismiss an FAA civil penalty for commercial drone use. The motion provides examples in four broad categories: Cinema and Television, The Model Aircraft Industry, Model Airplane Operators Who Are “Sponsored” or Compensated at Competitions, and Media Coverage and Entertainment. ## Wednesday, October 2, 2013 ### Fedora OpenMDAO Install OpenMDAO is "an open-source MDAO framework written in Python." It is an easy install (though not packaged for Fedora yet as far as I can tell). The only odd thing in the system requirements is the Chrome web browser for the GUI. They say things should work with Firefox (not Internet Explorer), but who cares? GUIs are for quiche-eaters anyway ; - ) The other requirements (Python, Scipy, Numpy, Matplotlib) are commonly packaged for a wide range of operating systems. OpenMDAO features, • Library of Built-in Solvers and Optimizers • Tools for Meta-Modeling • Data Recording Capabilities • Support for Analytic Derivatives • Support for High-Performance Compute Clusters and Distributed Computing • Extensible Plugin Library ## Monday, September 30, 2013 ### CFD V&V Case Resources This list is from a discussion on the CFD group on LinkedIn. • CFDOnline Validation and Test Cases: wiki with problem descriptions and some calculation results but not case files / grids (on the handful that I checked) • ERCOFTAC Classic Collection: "The database has undergone some re-structuring and expansion to include, amongst other things, more details of the test cases, computational results, and results and conclusions drawn from the ERCOFTAC Workshops on Refined Turbulence Modelling. At the moment, each case should contain at least a brief description, some data to download, and references to published work. Some cases contain significantly more information than this." Registration required. • LaRC Turbulence Modeling Resource: " The objective is to provide a resource for CFD developers to obtain accurate and up-to-date information on widely-used RANS turbulence models, and verify that models are implemented correctly. This latter capability is made possible through "verification" cases. This site provides simple test cases and grids, along with sample results (including grid convergence studies) from one or more previously-verified codes for some of the turbulence models. Furthermore, by listing various published variants of models, this site establishes naming conventions in order to help avoid confusion when comparing results from different codes." • CFD and Coffee: a list of resources focused on compressible RANS V&V. • cfd-benchmarks: benchmarks focused on room air distribution • Saturne Test Cases: a list of test cases for Code Saturne, which also links the Working Group 21 AGARD database among others • NPARC Alliance Verification and Validation Archive: grids available, but not much grid convergence info • Vassberg's NACA 0012 Grids: Hegedus Aero code-to-code calcs based on 2009 AIAA paper / grids for NACA 0012 I added the link to a Hegedus Aero page detailing his code-to-code and grid convergence results based on a previous AIAA paper and those same grids. The AIAA paper that page is based on is worth a read. ## Friday, September 27, 2013 ### SU2 and OpenMDAO Joint Workshop Here's an announcement for an exciting workshop combining the open source computational fluid dynamics code SU2 with the open source optimization framework OpenMDAO. Dear Colleagues, This is a friendly reminder about the OpenMDAO and SU2 joint workshop on Sept.30 - Oct.1 in Durand 450 (Stanford University). So far, we have had great interest for both in-person, and virtual attendance to the event and we are looking forward to a great workshop. There is still room for more participants and we encourage you to join us for as much workshop as you can. As a reminder, no experience with the software is necessary. If you plan on attending in-person or virtually, all participants should register at the SU2 homepage: http://su2.stanford.edu For virtual attendance, you must additionally register for the online webinar at the following locations: Day 1: https://attendee.gotowebinar.com/register/7114168239445654785 Day 2: https://attendee.gotowebinar.com/register/208563415407826177 OpenMDAO is an open-source framework for Multidisciplinary Design, Analysis and Optimization (MDAO). Written in Python, it functions to integrate analysis tools into a single design environment allowing for the investigation of engineering designs and optimization of designs subject to user requirements. SU2 is an open-source numerical PDE solver that can be used to solve the equations of fluid motion. SU2 has been used to simulate a range of fluid including wind turbines, supersonic business jets, and hypersonic re-entry vehicles. These powerful codes are suitable for general purpose applications. They have been downloaded more than ten-thousand times and have a continually growing footprint in a growing field of research. Because these codes are freely available and can be modified to suit specific needs, they can be used as part of countless research problems. If you’re interested in multi-physics simulations applied to design, this is the workshop for you! Each day will have a morning session to introduce the software packages and an afternoon session to give hands-on experience working with the codes. These sessions will focus on linking OpenMDAO and SU2 for specific multi-disciplinary problems. The best utilization of the two packages will be awarded an iPad!. The deadline for the competition (only on-site workshop attendees) will be on Thursday afternoon (October 3rd) and the winner will be announced on October 4th in the SU2 website. The agenda for the workshop is attached. Food will be provided both days. We hope you are able to join us for this exciting and engaging event! Cheers, The SU2 and OpenMDAO development teams I wish I could spare the two days to participate virtually; looks like a really good event. Update: Workshop Materials Update: videos and more from the workshop. ### SCRAMSPACE: Launch Anomaly Tough day at Andoya Rocket Range for University of Queensland SCRAMSPACE team. My heart goes out to these guys; they put a lot of good time, effort and smarts into their experiment. Here's the official statement: “The rocket carrying the scramjet launched at 3pm (Norwegian time, 11pm Brisbane time), however the payload failed to achieve the correct altitude to begin the scientific experiment as planned. “The SCRAMSPACE payload, according to our data, was operating perfectly and performed extremely well before and during the launch, and we received telemetry data all the way into the water. “Unfortunately the failed launch meant we could not carry out the experiment as planned.” “The team is very disappointed. The project represents a lot of time, effort and money by a committed consortium of partners and sponsors.” University of Queensland Hypersonics Chair Professor Russell Boyce ## Thursday, September 26, 2013 ### GE Jet Engine Bracket Challenge: Phase I Winners I wrote previously about some neat entries in the GE Engine Bracket Challenge on GrabCAD that used topology optimization. As reported by GE, they have picked their winners from Phase I. Phase I consisted of simulating the submitted parts in several different load cases and ranking them by how much weight the designer was able to shave off. Located around the world, finalists include: • Ármin Fendrik, based in Hungary, is a third-year university student and this entry is among his first 3D printing designs. • Thomas Johansson, Ph.D, based in Sweden, is a consultant for a Swedish hyper-car manufacturer and is a champion snowmobile drag racer. • Nic Adams, based in Australia, supported the installation of a pathology lab automation system in a Sydney hospital, which includes a robotic handling system that helps analyze hundreds of test tubes each day. • M Arie Kurniawan, based in Indonesia, is co-founder of an engineering firm that provides high quality mechanical engineering, design optimization and product design services. • Sebastien Vavassori, based in the United Kingdom, is a stress engineer for a leading European space manufacturer and service provider. • Piotr Mikulski, based in Poland, works as a rapid prototyping systems specialist for a Polish-Swiss joint-venture that provides industrial and machining services. • Andreas Anedda, based in Italy, is a postgraduate university student and holds three patents. • Alexis Costa is based in France. • Mandli Peter is based in Hungary. • Fidel Chirtes is based in Romania. These winner from Phase I will have their designs "printed" in Titanium and then tested by GE to determine the winners for Phase II. ## Wednesday, September 18, 2013 ### Falcon UAV Air Support in Colorado Fellow AFIT-alum Chris Miser doing good stuff in the Civil UAV market. Airpower to the People! In the wake of the recent floods in Colorado, Falcon UAV has spent the last three days providing volunteer aerial services to the Boulder County Emergency Operations Center (EOC) and the Incident Management Team (IMT). On Thursday afternoon while all National Guard aircraft were grounded due to weather Falcon UAV was proud to have been the only aircraft that was able to take flight to support the flood efforts in Lyons. Falcon UAV Supports Colorado Flooding Until Grounded by FEMA ## Sunday, August 25, 2013 ### SU2 Now on Git: Build and Install Latest on Fedora As I wrote previously the Stanford University Unstructured (SU2) code is now available on git hub. Here's the steps to get the latest code, build and install it. • Use the git client to clone the repo:  git clone https://github.com/su2code/SU2  • Follow the 'from source' install instructions for your system. It is should look something like:  ./configure make make install  This will give you (after a little help from the kindly devs) a plain-Jane version of SU2 for serial computations, without CGNS or Metis (graph partitioning) support. Happy number crunching! ## Wednesday, August 21, 2013 ### 3-D Printing in DoD: Who's Dragging Their Feet? I found this article, Why is the Pentagon Dragging Its Feet on 3D Printing, by way of Small Wars Journal. It has some interesting information. The Army is deploying mobile Fab Labs, which seems like a mini MIT FabLab in a shipping container. I think this is a really neat idea. How this can be characterized as feet dragging, I'm not sure. The feet dragging accusation is based on some hand-waving from an article on Disruptive Thinkers, and another article that seems to be worried that there is no Pentagon overlord in charge of an additive manufacturing strategy: With possible dwindling budgets on the horizon, a clear strategy and cohesive approach is essential to create efficiencies in the area of research and development as well as eliminating duplicative efforts. In order for DoD to take advantage of what is anticipated to be an explosion in the commercial sector within the next ten years, the Department must take an active approach, partnering with the private sector to keep up with this relatively nascent technology and shaping/guiding it towards the desired end state the department has in mind. One step towards a clear strategy and cohesive approach is for DoD to designate an AM Czar within the Department. They could serve as a single point for all things AM and not the myriad of technical advisory boards that currently exist. This office could then work with policy makers to execute and monitor a strategy which will allow DoD to take full advantage of this technology. Logically, this office would interface directly with the National Additive Manufacturing and Innovation Institute (NAMII) as DoD's representative 3-D Printing Revolution in Military Logistics I think an "additive manufacturing Czar" sounds like a terrible idea (so I'm sure it will secure funding for some beltway bandits to do a study). I know my recent success with qualifying a particular additive manufacturing process and supplier for use in 3D printing wind tunnel models did not need a Pentagon king-pin to tell me about DoD's strategy for additive manufacturing. Using this technology just made sense as a way to solve my problem: get a complex wind-tunnel model rapidly, and at an affordable cost. I did not receive top-down direction or guidance to use AM, I simply took the initiative to solve my problem. After reading that article I'm left wondering, just how exactly is waiting on direction from the very heights of the bureaucracy supposed to lead to innovation? ## Monday, August 19, 2013 ### UberCloud HPC Experiment I think I originally saw a link for the UberCloud HPC Experiment on one of the "This week in CFD" posts on Another Fine Mesh. It is a market research exercise to see how people would use cloud computing (platform as a service, software as a service) for their high performance computing workloads. The focus of the experiment is on the difference between enterprise work-loads and high-performance or scientific computing work-loads. Here's some of the introduction describing the research: We found that, in particular, small- and medium-sized enterprises in digital manufacturing would strongly benefit from HPC in the Cloud (or HPC as a Service). The major benefits they would realize by having access to additional remote compute resources are: the agility gained by speeding up product design cycles through shorter simulation run times; the superior quality achieved by simulating more sophisticated geometries or physics; and the discovery of the best product design by running many more iterations. These are benefits that increase a company’s competitiveness. Tangible benefits like these make HPC, and more specifically HPC as a Service, quite attractive. But how far away are we from an ideal HPC cloud model? At this point, we don’t know. However, in the course of this experiment as we followed each team closely and monitored its challenges and progress, we gained an excellent insight into these roadblocks and how our teams have tackled them. UberCloud HPC Experiment: Compendium of Cases Each of their teams has an industry user, a resource provider, a software provider, and an HPC expert. This part on applications is interesting: By far, computational fluid dynamics (CFD) was the main application run in the cloud by the Round 1 and Round 2 teams – 11 of the 25 teams presented here concentrated their efforts in this area. I think this really helps make the case for open source CFD codes: In addition to unpredictable costs associated with pay-per-use billing, incompatible software licensing models are a major headache. Fortunately many of the software vendors, especially those participating in the Experiment, are working on creating more flexible, compatible licensing models, including on-demand licensing in the cloud. Paying a per-core license makes no sense for these large jobs. One of the interesting use cases was from Team 30 who used an open source stack (Elmer, CAELinux) on top of Amazon Web Services Elastic Compute Cloud. ## Saturday, August 17, 2013 ### UAVs Aquiline and Axillary in Declassified U2 Documents The National Security Archive has an extensive page up on a previously released CIA report on the U2 program that has now been released with significantly less redaction. One of the interesting un-redacted sections has to do with two CIA UAV programs, Aquiline and Axillary. According to an interview conducted by Thomas P. Ehrhard, Aquiline was a stealthy propeller-driven, low altitude, anhedral-tailed UAV called Aquiline and designed for low-level electronic surveillance of the Chinese nuclear program. Aquiline was designed by McDonnell Douglas in the late 1960s and advanced to flight testing, but never saw operational use due to reliability problems. The aircraft was to be controlled by data link from a high-flying U-2. Air Force UAVs: The Secret History  Aquiline Axillary was a radar-homing drone by Melpar. The UAV section is in Appendix E. ## Wednesday, August 14, 2013 ### ITAR Public Domain: DIYDrones and Defense Distributed What is public domain for ITAR compliance purposes? Apparently, being available on a NASA website for years and widely available to the public without restriction is insufficient (and frustrating for aero engineers like me!). This question has raised discussion on the DIYDrones site: By and large, open-source qualifies as public domain, so the active technology being created free by the Internet and shared by the Internet means it's exempted. --Chris Anderson, DIYDrones founder 5 steps to cutting costs: Open-source leads to regulatory breaks Anderson goes in to more detail, Autopilots are export controlled by the International Traffic in Arms Regulations (ITAR), which is why it's very difficult for US manufacturers to sell abroad without incredibly complicated guarantees about security procedures put in place by the buyer. That doesn't just apply to autopilot hardware; it also covers autopilot software, groundstation code and other technology in digital form such as schematics. And "export" doesn't just mean physically sending boxes abroad, it also covers "export by electronic means" such as over the Internet. So why haven't we been arrested? We publish autopilot code, schematics and PCB design files here, and nearly half of our user base is outside the US. The answer is the "public domain exclusion" in ITAR. Because we're open source and release everything to the general public, it's no longer subject to export control. Why haven't we been arrested? The argument Anderson is making is the same one that Cody Wilson made about his Wiki Weapons project. Wilson took a "belt and suspenders" approach to getting his files into the public domain, Wilson argues that he’s also legally protected. He says Defense Distributed is excluded from the ITAR regulations under an exemption for non-profit public domain releases of technical files designed to create a safe harbor for research and other public interest activities. That exemption, he says, would require Defense Distributed’s files to be stored in a library or sold in a bookstore. Wilson argues that Internet access at a library should qualify under ITAR’s statutes, and says that Defcad’s files have also been made available for sale in an Austin, Texas bookstore that he declined to name in order to protect the bookstore’s owner from scrutiny. State Department Demands Takedown Of 3D-Printable Gun Files For Possible Export Control Violations However we see two very different trajectories in each case. DIYDrones is merrily turning out hardware and software, and publishing it all online, while Defense Distributed recieves take-down letters from the State Department. I can't see in the ITAR definition of public domain how the two situations should recieve different treatment. § 120.11 Public domain. (a) Public domain means information which is published and which is generally accessible or available to the public: (1) Through sales at newsstands and bookstores; (2) Through subscriptions which are available without restriction to any individual who desires to obtain or purchase the published information; (3) Through second class mailing privileges granted by the U.S. Government; (4) At libraries open to the public or from which the public can obtain documents; (5) Through patents available at any patent office; (6) Through unlimited distribution at a conference, meeting, seminar, trade show or exhibition, generally accessible to the public, in the United States; (7) Through public release (i.e., unlimited distribution) in any form (e.g., not necessarily in published form) after approval by the cognizant U.S. government department or agency (see also § 125.4(b)(13) of this subchapter); (8) Through fundamental research in science and engineering at accredited institutions of higher learning in the U.S. where the resulting information is ordinarily published and shared broadly in the scientific community. Fundamental research is defined to mean basic and applied research in science and engineering where the resulting information is ordinarily published and shared broadly within the scientific community, as distinguished from research the results of which are restricted for proprietary reasons or specific U.S. Government access and dissemination controls. University research will not be considered fundamental research if: (i) The University or its researchers accept other restrictions on publication of scientific and technical information resulting from the project or activity, or (ii) The research is funded by the U.S. Government and specific access and dissemination controls protecting information resulting from the research are applicable. Previous cases have shown that the restrictions on publishing source code for cryptography violate the First Amendment, why wouldn't restrictions on publishing gcode for 3d printing a drone or a pistol? I think the First Amendment problems around the Defense Distributed case are the real interesting part of this. Wilson's provocations are not really about the 2nd Amendment, the gun is just a clever marketing hook. His focus is on political speech and freedom of the means of production, PCMag: Are freely available guns the core of your political beliefs or a part of that larger ideology? Wilson: No, I think it's a very clever way of unpacking the ideology for people. A lot of people get there and stop at the gun. And that's great, like some of the Second Amendment people who are like, "Alright, this is great for guns." No, I think it's more importantly a signal of the future and it helps through just getting at some of these bigger ideas. Dismantle the State: Q&A with 3D Gun Printer Cody Wilson In another article, Wilson said we’re not so much dealing with firearms regulation as “what can be put into the public domain and how.” “It’s a demonstration of claiming everything in the national security interest,” he said. “They say, ‘well, your useless plastic gun can’t be shared with other people. It’s important to national security.’ In the end, everything will be claimed…” It seems to be “consistent [with] the total bureaucratization of social space itself,” Wilson continued. 'In the End, Everything will be Claimed' Probably the biggest reason for the difference in treatment between DIYDrones' Chris Anderson and Defense Distributed's Cody Wilson is that Anderson wanted to build toys for his kids, while Wilson wants to take on the Leviathan. Lesson: be careful what you wish for. ## Monday, August 12, 2013 ### SU2 Now on Git Good news for Open Source Computational Fluid Dynamics from the SU2 team: The Stanford University Unstructured (SU2) development team is proud to announce that the open-source SU2 suite has moved to GitHub! This change makes it much easier for individuals and groups to use and modify the code for their own purposes. It also means that now SU2 is more open than ever. Moving to GitHub is an important and exciting step for SU2, and we are looking forward new contributions from the community in the true spirit of open-source software. Users who wish to work with the code will now find that all of the capabilities they require to track modifications are already in place. Copying the code and submitting revisions is easier than ever with GitHub's "fork" and "pull request" features. In the year and a half since our initial release, SU2 has been downloaded over 5,700 times, and the main SU2 website has received over 45,000 visits from around the world. Our forum hosted by CFD online sees an abundance of activity from many of our users. SU2 is under active development in the Aerospace Design Lab (ADL) in the Department of Aeronautics and Astronautics at Stanford University and is released under an open-source license. More information can be found at: Thank you for your interest and support! The SU2 team I think this is a really good thing (see previous discussion about SU2 being more open). You may say, why do we need another open source CFD code, don't we already have OpenFOAM? Yes we do, but OpenFOAM is focused on industrial CFD applications that tend to have incompressible formulations and methods. SU2 is a compressible flow finite-volume code (with lots of neat design optimization capabilities too). If you come from the compressible flow world, then you'll find the schemes and methods (upwind/flux splitting, TVD limiters, etc) in SU2 are right in your comfort zone. The beauty of open source is that we can have all these complimentary options to fill different niches. ## Thursday, August 8, 2013 ### Novel Processes for Advanced Manufacturing: Summary of a Workshop (2013) ## Sunday, August 4, 2013 ### A Defense of Computational Physics This is a defense a long time in the making (h/t Dan Hughes). Patrick Roache has done short articles along a similar vein defending the Computational Physics enterprise against what amounts to an empty nihilism that seems to be popular among academics. Here is the publisher's description, Karl Popper is often considered the most influential philosopher of science of the first half (at least) of the 20th century. His assertion that true science theories are characterized by falsifiability has been used to discriminate between science and pseudo-science, and his assertion that science theories cannot be verified but only falsified have been used to categorically and pre-emptively reject claims of realistic Validation of computational physics models. Both of these assertions are challenged, as well as the applicability of the second assertion to modern computational physics models such as climate models, even if it were considered to be correct for scientific theories. Patrick J. Roache has been active in the broad area of computational physics for over four decades. He wrote the first textbooks in Computational Fluid Dynamics and in Verification and Validation in Computational Science and Engineering, and has been a pioneer in the V&V area since 1985. He is well qualified to confront the mis-application of Popper's philosophy to computational physics from the vantage of one actively engaged and thoroughly familiar with both the genuine problems and normative practice. Here is a short excerpt from one of Roache's papers that gives a flavor of the argument he is addressing, In a widely quoted paper that has been recently described as brilliant in an otherwise excellent Scientific American article (Horgan 1995), Oreskes et al (1994) think that we can find the real meaning of a technical term by inquiring about its common meaning. They make much of supposed intrinsic meaning in the words verify and validate and, as in a Greek morality play, agonize over truth. They come to the remarkable conclusion that it is impossible to verify or validate a numerical model of a natural system. Now most of their concern is with groundwater flow codes, and indeed, in geophysics problems, validation is very difficult. But they extend this to all physical sciences. They clearly have no intuitive concept of error tolerance, or of range of applicability, or of common sense. My impression is that they, like most lay readers, actually think Newton’s law of gravity was proven wrong by Einstein, rather than that Einstein defined the limits of applicability of Newton. But Oreskes et al (1994) go much further, quoting with approval (in their footnote 36) various modern philosophers who question not only whether we can prove any hypothesis true, but also “whether we can in fact prove a hypothesis false.” They are talking about physical laws—not just codes but any physical law. Specifically, we can neither validate nor invalidate Newton’s Law of Gravity. (What shall we do? No hazardous waste disposals, no bridges, no airplanes, no...) See also Konikow & Bredehoeft (1992) and a rebuttal discussion by Leijnse & Hassanizadeh (1994). Clearly, we are not interested in such worthless semantics and effete philosophizing, but in practical definitions, applied in the context of engineering and science accuracy. Quantification of Uncertainty in Computational Fluid Dynamics, Annu. Rev. Fluid. Mech. 1997. 29:123–60 ## Saturday, August 3, 2013 ### Navier Stokes 12 Step Program By way of another fine mesh, Boston University’s Prof. Lorena Barba has released a 12 Step Program for Navier-Stokes. It is a self-paced introductory CFD course presented based on IPython Notebooks. From the site: We announce the public release of online educational materials for self-learners of CFD using IPython Notebooks: the CFD Python Class on Bitbucket The course starts with simple one dimensional toy problems and progresses through Burger's equation, then to two dimensions and then finally to Navier-Stokes in 2D. Looks neat, can't wait to try out the notebooks. ## Saturday, July 20, 2013 ### Topology Optimization in GE Jet Engine Bracket Challenge Entry There is an interesting contest on GrabCAD for designing a lighter weight engine bracket for a GE engine the winner of which GE will produce and test using an additive manufacturing method (maybe DMLS). One of the contestants used PareTO software (methods based on these matlab scripts I linked previously) to design a pretty nice looking bracket. Update: There are more entries that are using topology optimization. • KMWE and TU Delft Team Entry. This comment the team makes is interesting: "Since the optimised topology models are in stl we have started to first create a volume model with stp extension so we meet the competition recuirements. This takes a lot of time!" This bottle neck in the work-flow is similar to the problem CFD analysts have with structured grid generation. While many (most) 3D printers will take an stl format file (which is just a triangulate surface), you still really want the normal CAD formats (parametric) for a couple reasons. Usually for the metal printing processes you have to add support material. This is done more easily / accurately with something other than an stl. Also you want to be able to use the part in larger assemblies, and this is likely to go better using a native CAD format. • GE Jet Engine Bracket v1.5, Topology Optimized Bracket - V4, by Igor Lins e Silva • GE-jet engine bracket-opti-design-phase 1, by Cheng.Li • Engine Bracket V2.1, by Igor Lins e Silva • GE Challenge, by Charlie Pyott. I like this one because he uses a lattice, which reminds me of the octet truss things I was working on previously. Charlie also has a website with other interesting designs. ## Monday, June 24, 2013 ### Octet Truss Improved Time Cost Previously, I did a quick and dirty scaling study on how long it takes to make a 3D cube of octet truss unit cells in BRLCAD. I posted some questions about the results to the list and got some good recommendations on speeding things up. The approach I used previously was just unioning a big, flat list of primitives. The main recomendation to get speed-up was to introduce a bit of spatial organization in the way the primitives are grouped. I did this by making each unit cell a region, and then making an assembly combination of the unit cells. This is only two levels of hierarchy, so ultimately the scaling is still quadratic. The speed-up is pretty dramatic though. To get the $$N log(N)$$ scaling mentioned on the email list would require an octree structure with an adaptive number of subdivision levels. Here's a plot showing the improved time scaling: ## Friday, May 10, 2013 ### ITAR Craziness in the News First it was the almost good news story on NASA's NTRS service coming back online The website of the NASA Technical Reports Server (NTRS), a massive collection of aerospace-related records, was disabled in March due to congressional concerns that it had inadvertently disclosed export-controlled information. (“NASA Technical Reports Database Goes Dark,” Secrecy News, March 21; “Database Is Shut Down by NASA for a Review,” New York Times, March 22.) The site is now active again, though hundreds of thousands of previously released documents have been withheld pending review. Rather than conducting a focused search for actual export-controlled information and then removing it, as would have seemed appropriate, NASA blocked access to the entire collection. The agency acted under pressure from Rep. Frank Wolf (R-VA) of the House Appropriations Committee while it assessed the situation. NTRS Back Online The FAS also got some emails describing the process for NASA to return the rest of the reports to public availability. Getting that error message back in March that the server was down was a pretty big shock. It's a very commonly used resource in the Aeronautical / Astronautical Engineering community. I hope they are able to get things restored rapidly! As if the NTRS fiasco wasn't enough export control weirdness for your week we also got a bit of a spectacle courtesy of Defense Distributed and the Directorate of Defense Trade Controls. the Directorate of Defense Trade Controls (“DDTC”) told Defense Distributed to take down the plans that it had posted for producing a crappy plastic handgun using an expensive 3-D printer. You can read the letter by clicking this link. [...] But leaving aside whether or not these plans are controlled technical data that cannot be put on the Internet without a DDTC license, this whole brouhaha seems to be a waste of time by DDTC. Real guns that won’t blow up in your hand, can fire multiple shots before falling apart, and which can be much more cheaply manufactured are readily available outside the United States, so the danger posed by exporting these plans is, well, non-existent. Foreign militaries aren’t very likely to abandon their AK47s now that they can print their own plastic handguns. Worse yet, the plans had apparently been downloaded more than a 100,000 times before the Feds dropped the ban hammer. There is no way that DDTC can now stuff all that toothpaste back in the tube. DDTC Slams Stable Door After The Horses Have Bolted The striking similarity in both cases is that the information in question had already been made widely available to the public, and the public had availed itself to it. In the NTRS case those reports had been available for years, and are widely used in engineering education and referenced in textbooks. The Defcad files were only available for a matter of weeks (the latest files were only added to the archive in the past few days), but had already been downloaded more than 100k times and were hosted on servers in New Zealand. Of course for a political animal like Cody Wilson getting a take-down order from the State Dept. is exactly the sort of thing he wants ## Sunday, April 21, 2013 ### Orbital Sciences Antares Launch Success ## Friday, April 5, 2013 ### A New Nuclear Rocket Concept The folks at University of Washington and MSWNW LLC. have a new Fusion Driven Rocket concept. It combines magnetic and inertial confinement to achieve fusion and subsequent fuel heating for high exhaust velocity. ## Thursday, April 4, 2013 ### UAV Crash Course NASA released a report on UAV mishaps, Crash Course: Lessons Learned from Accidents Involving Remotely Piloted and Autonomous Aircraft The findings echo decades of flight operations experience: mishaps are usually the result of a "chain" of circumstances that individually would probably not cause a problem. Here's NASA's description of Crash Course: This volume contains an investigation of remotely piloted research vehicle (RPRV) and unmanned aircraft system (UAS) mishaps and will examine their causes, consequences, resultant corrective actions, and lessons learned. Most undesired outcomes usually do not occur because of a single event, but rather from a series of events and actions involving equipment malfunctions and/or human factors. This book comprises a series of case studies focusing mostly on accidents and incidents involving experimental aircraft. The information provided should be of use to flight-test organizations, aircraft operators, educators, and students, among others. These lessons are not unique to the UAS environment and are also applicable to human aviation and space flight activities. Common elements include crew resource management, training, mission planning issues, management and programmatic pressures (e.g., schedule, budget, resources), cockpit/control station design, and other factors. ## Saturday, March 30, 2013 ### Midwest Pilot vs Euro Factories of the Future I wrote a bit previously about the midwest pilot to increase penetration of high performance computing and simulation into the small and medium enterprises (SMEs) of the US mid-western regional manufacturing supply chain. The similarity to the European 'factories of the future' program jumped out at me as I was reading the recent article in Aerospace America, 'International Beat: Printing your next vehicle'. The article describes the European program: 'Factories of the Future' was set up in 2009, a €1.2-billion public-private partnership between the EC and industry. The research program focuses on the development of new and sustainable technologies highlighted by the Ad-Hoc Industrial Advisory Group to the commission, to help EU manufacturing enterprises--in particular small and medium-sized enterprises--to adapt to global competitive pressures by improving their technological base. Research areas include new models of production systems (transformable factories, networked factories, learning factories); ICT-based production systems and high-quality manufacturing technologies (including research into increasing autonomous production lines); and sustainable manufacturing tools, methodologies, and processes producing assemblies with complex and novel materials. With the completion of the EC's seventh framework research program this year, EFFRA has been working to continue the research within the commission's new seven-year research program, Horizon 2020. This will focus on: • Advanced manufacturing processes. • Adaptive and smart manufacturing systems • Digital, virtual, and resource-efficient factories • Collaborative and mobile enterprises • Human-centered manufacturing • Customer-focused manufacturing Contrast with this from the Council on Competitiveness: The Council on Competitiveness and selected original equipment manufacturers (OEMs) are developing a Midwestern regional pilot program as a public-private partnership with the U.S. federal government. The pilot program is aimed at improving competiveness and innovation in small- and medium-size enterprises (SMEs) in the U.S. manufacturing supply chain. The ultimate outcome of the pilot program will be a workforce with enhanced technical skills, improved product quality, better customization of products, and job retention and growth. [...] The high level goal of this pilot program is to develop and demonstrate a sustainable, scalable and replicable model for accelerating and broadening use of modeling, simulation and analysis (MS&A) in Midwestern SMEs through a public-private partnership (described below). Funding will be provided as seed money for this pilot program, with the expectation that it will demonstrate a path toward long-term sustainability. This is only achievable if (a) the supply chain members can rapidly reach a point where the results produce cost-benefits that allow and incentivize them to continue use of MS&A, either independently or within the continued context of the pilot program, and (b) software vendors can develop a business model that provides easier and more affordable access to software tools for SMEs. These manufacturing competitiveness initiatives seem to be focused on additive manufacturing or 3D printing right as this technology peaks on Gartner's hype cycle.  3D Printing Tops the Gartner Hype Cycle 2012 Hopefully something useful will be left for us makers, hackers, engineers and small business owners when all the smoke clears and the twittering classes move on to the next big thing. I think this DIY Rocket thing is a clear indication of the heights of unreasonable expectations that we've reached. It is important to sift through the silliness because there's some really good and useful technology to be exploited here. ## Tuesday, March 26, 2013 ### Playing around with SU2 Compressible Flow Solver The folks at Stanford's Aerospace Design Lab have an open source solver called Stanford University Unstructured (SU2) (AIAA ASM 2013 paper). The nice thing about this code is that it does not have very many third-party dependencies, so you can just download the source and compile with a pretty plain vanilla system that is probably already installed on your Linux workstation of whatever flavor. There are lots of example input decks in the TestCases tarball so be sure to download that as well.  NACA0012, Mach=0.5, AoA=1.0 degrees, hybrid mesh Few exotic dependencies and easy portability across systems is a definite plus, but one of the things I don't like so much about their development model is that you have to register to get the links to the source. The license may be GPL, but it's not really an open development model yet. I understand that this is a bit of an experiment with open source for the folks at Stanford, and they want to track how many visits and registrations they get, but I'd encourage them to go open all the way: let everyone have read access to the repo without registration; put it up on git and let a bunch of forks bloom! ## Friday, March 15, 2013 ### HIFiRE Flight 1 Seminar at UMich If you are in the University of Michigan area there is a seminar about HIFiRE Flight 1 Boundary Layer Transition experiment. • AE 585 Seminar Series: 'HIFIRE-1 Hypersonic Flight Test', by Dr. Roger Kimmel of Air Force Research Laboratory • March 21, 2013 / 4:00PM • Boeing Lecture Hall, FXB Details on the University of Michigan site here. ## Sunday, March 10, 2013 ### Coefficient of Thermal Expansion Mismatch: Shapeways Steel-Bronze Composite  Bronze 420 Steel CTE (ppm/oF) 10.3 5.7 Conductivity (Btu/(hr oF ft)) 15 14.4 The DIYROCKET organization is sponsoring a contest to design a 3-D printed rocket for nano-satellite launch (coverage on Parabolic Arc and Make). Shapeways is one of the competition's sponsors so one of the rules is that you have to use their metal 3-D printing process. The process is not direct to metal, i.e. directly melts the final part material. Their process melts a polymer binder to 'glue' stainless steel powder into the shape of the part, the plastic is then burned out of this green part, and the voids are infused with bronze. The result is a steel-bronze composite with either 30% or 40% (by volume? weight?) bronze content (different parts of the Shapeways site have different numbers). ## Friday, March 8, 2013 ### SciPy John Hunter Excellence in Plotting Competition In conjunction with the SciPy 2013 Conference there will be an excellence in plotting competition sponsored by NumFocus as a memorial to the former lead developer of matplotlib, John Hunter. Entries are due by email no latter than 2 April 2013. The cash prizes are • 1st prize:$500
• 2nd prize: $200 • 3rd prize:$100
Here are the instructions:
• Plots may be produced with any combination of Python-based tools (it is not required that they use matplotlib, for example).
• Source code for the plot must be provided, along with a rendering of the plot in a vector format (PDF, PS, etc.). If the data can not be shared for reasons of size or licensing, "fake" data may be substituted, along with an image of the plot using real data.
• Entries will be judged on their clarity, innovation and aesthetics, but most importantly for their effectiveness in illuminating real scientific work. Entrants are encouraged to submit plots that were used during the course of research, rather than merely being hypothetical.
• SciPy reserves the right to display the entry at the conference, use in any materials or on its website, providing attribution to the original author(s).

## Wednesday, March 6, 2013

### GBU-8 Photogrammetry

More photogrammetry. This uses the same software tool chain I described before. Still needs a bit of work on surface reconstruction. I always underestimate how many pictures are needed to get a reasonable point cloud: more is better.

I took the pictures of the GBU-8 at the NMUSAF. The surprising thing to me was the landing gear on the aircraft in the background showing up so well.

## Monday, March 4, 2013

### Drone Marketing, Same Song Second Verse

I enjoy these advertising shorts. Nothing new under the sun (well, the cartoons have improved).

Update: A new one from LockMart.

## Saturday, February 23, 2013

### 3D Printing is a Hot Political Topic

3D printing or additive fabrication is a hot topic, and not just to the engineers, fabricators and hobbyists anymore. It seems to be becoming part of the political symbology wrapped up in economic recovery or development. As I commented on the Made in Dayton blog, the National Academies Press recently released a report about Building the Ohio Innovation Economy that includes significant emphasis on additive fabrication, and the President mentioned the National Additive Manufacturing Innovation Institute, located in Youngstown, in his State of the Union address. There is also the Midwest Pilot for connecting High Performance Computing (HPC) resources to small and medium manufacturing concerns. As we saw in this topology optimization post, there is considerable need for scale-able computational approaches to fully realize the promise of additive manufacturing. Closer to home, your Dayton hackerspace is playing with a printrbot.

## Sunday, February 17, 2013

### Dayton Masonic Temple Photogrammetry

 Bundler-PMVS2 Dense Point Cloud Visualization in Meshlab
I wanted to experiment with some free photogrammetry software, and the Masonic Temple in Dayton is a nice target of opportunity. There are some free (as in beer) options, but I wanted something that was free (as in freedom) that I could run on my own machines rather than in a software-as-a-service cloud. The basic work-flow is demonstrated in this post by Andrew Hazelden for some aerial photographs. He gets fairly impressive results using only free software.

## Wednesday, February 13, 2013

### Efficiently Directing the Work

The good Colonel knew it in 1918,
no man can efficiently direct work about which he knows nothing
--Col Thurman H. Bane
and we can rediscover it nearly a century later,

Item 19 of the checklist stresses the importance of placing experienced, domain-knowledgeable managers in key program positions. The committee has observed that many of the truly extraordinary development programs of the past, such as Apollo, the Manhattan Project, the early imaging satellite programs, the U-2, the fleet ballistic missile system, and nuclear submarines, were managed by relatively small (and often immature) agencies with few established processes and controls. In that environment, dedicated managers driven by urgent missions accomplished feats that often seem incredible today.

The committee believes that the accumulation of processes and controls over the years—well meant, of course—has stifled domain-based judgment that is necessary for timely success. Formal SE processes should be tailored to the application. But they cannot replace domain expertise. In connection with item 19, the committee recommends that the Air Force place great emphasis on putting seasoned, domain-knowledgeable personnel in key positions—particularly the program manager, the chief system engineer, and the person in charge of “requirements”—and then empower them to tailor standardized processes and procedures as they feel is necessary.

[...]

While the systems engineering process is, broadly, reusable, it depends on having domain experts who are aware of what has gone wrong (and right) in the past recognize the potential to repeat the successes under new circumstances and avoid repeating the errors.

Pre-Milestone A and Early-Phase Systems Engineering: A Retrospective Review and Benefits for Future Air Force Acquisition

When I read that last part it reminded me of something Herbert Mason said at a talk he gave recently at the NMUSAF: "History makes you smart, heritage makes you proud."

## Tuesday, February 12, 2013

### Environmental Decisions in the Face of Uncertainty

New report from the National Academies Press on decision making under uncertainty.

Description: The U.S. Environmental Protection Agency (EPA) is one of several federal agencies responsible for protecting Americans against significant risks to human health and the environment. As part of that mission, EPA estimates the nature, magnitude, and likelihood of risks to human health and the environment; identifies the potential regulatory actions that will mitigate those risks and protect public health1 and the environment; and uses that information to decide on appropriate regulatory action. Uncertainties, both qualitative and quantitative, in the data and analyses on which these decisions are based enter into the process at each step. As a result, the informed identification and use of the uncertainties inherent in the process is an essential feature of environmental decision making.