Dartmouth Engineer - The Magazine of Thayer School of EngineeringDartmouth Engineer - The Magazine of Thayer School of Engineering

Just One Question: What’s the hardest engineering challenge you’ve ever faced?

My hardest engineering challenge was to come up with a jet engine pressure-ratio transducer. They were all analog electro-mechanical devices in those days, and a bright young engineer had a fancy geometric way of doing it with fine wires that didn’t work out. The transducer division took my invention of a pure-crystalline silicon hollow evacuated cylinder with a very thin closure at one end that served as a diaphragm with thin n-p-n channels configured as a strain-gauge bridge. A young engineer that I had spirited from my former job developed the analog electronic circuits to provide an output linear vs. absolute pressure. That had its own significant error, multiplied by the error of analog computing the ratio of outputs of two instruments. Not good enough. An excellent company bought the patent and made a lot of money by developing producible transducers and digitizing the outputs for accurate division.
—Tom Harriman ’42 Th’43

In the early 1980s Baxter & Woodman, a consulting engineering firm of which I was then president, was retained by the Village of Deerfield, Ill. We were asked to conduct an in-depth investigation of its sanitary sewer system, which for decades had been subject to extensive flooding, resulting in frequent and massive backups into basements. The study was to be an “infiltration-inflow” evaluation to identify and quantify the sources of groundwater and storm water. At that time information on the causes and sources of infiltration and inflow was limited and a subject of discussion and supposition, so we were entering into somewhat unexplored territory and had to develop equipment and procedures. One of the infiltration sources was sump pumps, which discharge into the house sanitary sewer connection. They were not believed to be pumping storm water, because the common belief was that surface water would take considerable time to percolate into the ground and reach the footing drains the sump pumps were serving. We installed some devices that we had fabricated to produce a time record of sump-pump operation, and found that most of the sump pumps in the study would be running full-bore for several hours, starting less than 15 minutes after the start of a significant rain event. We also blocked off sections of the storm sewers, which we then filled from a fire hydrant, and observed the increase in flow in the nearby sanitary sewer, measuring it from the velocity read with miniature flow meters and locating the leaks with submersible television cameras. We identified thousands of sources of infiltration and inflow totaling more than 70 million gallons per day leaking into the sanitary sewer system, which was designed for a sewage flow of 2–5 million gallons per day. (I presented a paper on our procedures and results to a standing-room-only audience at a national conference of the Water Pollution Control Federation.)

We estimated the cost of correcting each of these sources of infiltration and inflow and arrayed them in order of cost effectiveness vs. augmenting the capacity of the sanitary sewer system, on which a highly effective $10 million remedial construction project was based, virtually eliminating the sewer backups that had plagued Deerfield for so long.
—Hjalmar Sundin ’47 Th’47

During a five-year period from late 1987 through early 1992, the firm I was then leading was threatened by bankruptcy. Modjeski and Masters was found liable by an Orleans Parish jury verdict of $9 million in a 1987 lawsuit following a head-on crash on the Greater New Orleans Bridge, which we had designed. Our insurance coverage was denied, and the liability, which greatly exceeded the firm’s net worth, extended to the partners’ personal assets. Our impecuniosity prevented us from filing a suspensive appeal (Louisiana requires a 150-percent full-value bond) and the plaintiff was beginning, in 1990, to file documents to seize the firm’s assets. However, the U.S. Supreme Court in late 1990 granted us an emergency stay of execution, and we were then able to file our appeal. The court of appeals in 1991 vacated the jury verdict and by early 1992 we had recovered most of our $1.1 million in legal costs from our former insurance company. This ended an unforgettable episode for my partners, my family, and me in my professional engineering career.
—William Conway ’52 Th’54

I was in charge of restoring a 50,000-square-foot clubhouse at Harbour Ridge Yacht and Country Club in Palm City, Fla., where we live. It was totally destroyed and rendered useless by two hurricanes in 2004. The clubhouse was redesigned to better suit the needs of both members and staff and reopened in 2006 to critical acclaim. It functions beautifully to this day and should do so for many years to come.
—Bob Simpson ’53 Tu’54 Th’54


Ron Read ’57 Th’58 designed a coal-water slurry transport system. Photograph courtesy of Ron Read.

Mining coal with water was the technical challenge of a lifetime. During the mid 1970s I was working at the Bendix corporate research labs in Southfield, Mich., as a senior project engineer. We had developed some proprietary capabilities for producing high-pressure (30,000-plus psi) water jet nozzles and intensifiers capable of cutting through almost any material. The U.S. Bureau of Mines was interested in the possibility of using water jets to mine underground coal. The objective was to reduce the hazard of mine fires and miner black lung caused by combustible coal dust generated by traditional mechanical drilling and continuous mining techniques. Bendix, teamed with the Consolidation Coal Co., was awarded an R&D project to begin developing a coal mine water jet/slurry transport system. There were two major technical challenges. One was to meet a production rate of 10 tons of coal extracted per minute. The other resulted from using high-pressure water jets to cut the coal at the working face. This would result in vast amounts of coal-water slurry to be transported out of the mine. The transport system had to have a low profile because of the low seam height typical of coal mines.

The Bendix task was to first develop a slurry transport system. When we put the engineering team together we discovered no one had ever worked in a mine environment or even been in a mine, except for me. My dad had been general manager for the International Salt Co. mine under the city of Detroit. During my summer breaks from Dartmouth my summer job was “back to the salt mines.” Based on these rather questionable qualifications, I was assigned as the project lead engineer. Our team found it was infeasible to haul the coal-water slurry using bulk transport because of the low haul way roof conditions. We decided on a hose transport system consisting of two 1-foot-diameter flexible hoses, one for water feed to the jet cutters and one for the slurry return. The hoses were positioned one on top of the other. The hose assemblies were clamped to each other and mounted to a steel I-beam linkage system with pin joints. The linkage and hose assembly was propelled by hydrostatically powered two-wheel carts attached to the linkage assembly every 25 feet. Our prototype hose hauler hardware was designed and built in a shortened 150-foot-length version, as the production design called for a 1,000-foot length.

The prototype system was delivered for testing to the Consolidation Coal Robinson Run Mine in West Virginia. This prototype tested perfectly, snaking through the narrow mine haul ways. Unfortunately, the second technical challenge of producing 10 tons per minute using the limited and inefficient energy conversion of water jet energy to coal face extraction rate proved impossible. The Bureau of Mines decided not to pursue further development. So today the 150-foot hose hauler sits underground gathering coal dust, waiting for a higher-powered, more-efficient water jet cutting system.
—Ron Read ’57 Th’58

My first civilian job after Vietnam service was at Dorr-Oliver as a program manager and lead sanitary engineer for a membrane bioreactor (MBR) project for advance wastewater treatment for the U.S. Navy. What was hard about this work was also its greatest joy: When you venture into truly new territory, there are no rules. The MBR process was patented by Dorr-Oliver in the late 1960s, and combined the use of an activated sludge bioreactor with a cross-flow membrane filtration loop. The objective was to efficiently treat wastewater to high purity in systems with a small footprint, low-energy consumption, and high biological stability. A cross-functional team of membrane scientists, mechanical, fluids, and sanitary (biological) engineers was assembled to develop and deliver a shipboard wastewater treatment system for a 200-man crew component. It was to be contained within a space envelope of 8-by-8-by-6-feet, allowing all service functions to be performed within an aisle adjacent to that space. Added challenges included fast startup, stability at sea, and operation in fresh- and salt-water environments.

Ivars Bemberis Just One Question
Ivars Bemberis ’64 Th’65 developed a shipboard wastewater unit. Photograph courtesy of Ivars Bemberis.

Simulation of performance under changing salinity conditions was a crucial part of the contract. Our studies demonstrated unambiguously that the reactor was “upset” by osmotic forces rupturing microbial cells. However, the combination of positive mass retention by the membranes and operation at high biomass concentrations maintained effluent quality through the upset period. The benefit of mass retention by the membranes also served to promote fast reactor startup after periods of non-use on the high seas.

There was significant concern over accumulation of suspended solids, because ultrafiltration membranes retained everything in the reactor. Long-term pilot studies with “real” waste provided a surprising and beneficial finding: Solid matter, particularly paper fiber, which traditionally is reduced under anaerobic conditions, was broken down in the aerobic-activated sludge reactor. Because the reactor biomass was notably higher than in conventional reactors, it was postulated that high biomass required additional nutrients, which triggered aerobic pathways for cellulose lysis.

An interesting side note of the Dorr-Oliver MBR activity was the installation of a wastewater treatment plant at the visitor center on top of Pikes Peak (elevation 14,114 feet) to treat wastewater for reuse. This plant operated for more than 20 years. Similarly, Sanki Ltd., a Japanese engineering partner, used this technology for wastewater recycling at Tokyo Central Station and many commercial buildings. When buildings incorporated wastewater reuse practices, occupancy limits could be increased, allowing construction of higher structures.
—Ivars Bemberis ’64 Th’65

Of my 50 years in technology, I think my hardest challenge was in ES 21: Introduction to Engineering my freshman year at Dartmouth. Our class was the first ES 21 class, so no one really knew how it would work. Our problem was to build an energy-conserving bicycle. That is, you ride downhill, the bike stores energy and carries you back uphill. There were four teams. My team had English majors, art majors, etc. Everyone in the class intellectually proved that it would not work. Our team decided to try it out, so we built a bike with a generator motor. We tried it on Tuck Hill. And it did not work, for the most part. So for our presentation we rode the bike into the classroom and then showed why it was not feasible. We won the competition. No one else had actually built a working model. And we learned a lifetime of things.
—Ed Keible ’65 Th’66

My hardest engineering challenge, other than actually graduating from Thayer, was qualifying as a chief engineer for a naval nuclear power plant on my first tour of duty on the USS Scamp. Four of my five years at Dartmouth were paid for through a NROTC scholarship, and in return I committed five years to the Navy, including going through nuclear power training and serving on two nuclear submarines, mostly at sea and mostly underwater at a time when the Cold War was about as hot as it got.

Clinton Harris Just One Question
Clinton Harris ’69 Th’70 served his first tour of duty on the USS Scamp. Photograph courtesy of Clinton Harris.

Once on board your first submarine, you went through a 12- to 18-month process of learning the engineering and how to operate every piece of equipment on the “boat” to earn your gold dolphins (like getting your wings as a pilot). The second stage, which very few officers were offered, was to complete your qualifications as a chief engineer. This included more schoolwork, more operations experience and going back to Washington, D.C., for a three-day exam ending with a second interview with Admiral Hyman Rickover, which I am proud to say I completed successfully in 1973.

My Thayer School training was a wonderful foundation for what I was able to achieve in the Navy. Thayer’s multidiscipline approach to engineering made it possible for me to quickly learn the full range of technologies on a modern nuclear submarine, from mechanical systems and thermodynamics all the way through to nuclear physics.  Thayer’s approach to teaching teamwork and project design was incredibly well suited to learning how to work with your shipmates in an environment where real-time, practical engineering was critical. The first rule of submarining is “to make your total number of times you surface at least equal to the total number of times you dive.”
—Clinton Harris ’69 Th’70

The California high-speed rail (HSR) project! For six years I have worked on the initial stages of North America’s first HSR system. I have been Aecom Technology Corp.’s regional consultant project manager on the first segment of the project, which will link San Francisco and Los Angeles. As the first of seven segments, the 65-mile Merced-to-Fresno segment required our team to work closely with numerous federal, state, and local agencies, communities, and stakeholders in creating the processes to develop alternative alignments for consideration, completing the federal and state environmental analyses, preparing the engineering design on the preferred route, creating environmental mitigation plans, obtaining all environmental permits, and assisting in property acquisitions.

Our efforts were rewarded with the start of construction in late 2014 on our $1 billion segment. We employed more than 400 individuals during the life of the project. We had many engineers designing over, under, through, and around communities and super-rich farmlands and orchards, while many biologists and other environmental engineers concerned themselves with impacts to people, landscape, endangered species, and the precious commodity of water. The total cost of the 450-mile system is projected at $68 billion, a very hefty price tag until compared to the more-than-double cost cost of new interstate highways and airport runways that will be needed to carry the same capacity to meet the 20 million-person immigration projections expected in California during the next 20 years.

Extensive outreach presentations of our work were required from the public community centers all the way up to the state and federal governmental agencies and legislatures. The HSR project is extremely emotionally charged—you either love it or hate it.

This project was an all-out sprint for six years, easily the longest, largest, toughest, most environmentally important and controversial transportation project I could ever have imagined I’d be participating in. Yet it was easy to sustain the required effort knowing how important the project is as the prototype for our country’s initial steps into this type of transportation. It was very hard and very satisfying. It was also fun to realize that a very high percentage of my studies at Thayer was called into play during this six-year roller coaster ride.
—Dick Wenzel ’71 Th’72

My hardest engineering challenge was convincing the Thayer School to allow me to complete my B.E. after my Dartmouth A.B. I failed.
—Robin Felix ’75

One of my most challenging and rewarding projects involved developing an instrument to identify and quantify the duration of stereotypical movements in kids with autism. “Stereotypy” refers to movement behavior that is repetitive, rhythmical, and non-goal directed. Stereotypy can be problematic in intensity and frequency, and can interfere with the ability of an affected individual to participate fully in educational or rehabilitative activities. Thus, for some individuals, stereotypy may be a target for intervention or a measure of the effectiveness of treatment.

While working at Creare Inc., a Hanover-based engineering R&D firm, I was the principal investigator on a National Institutes of Health-funded project to address this problem, which came to our attention during a perfect storm of technology development. Very small, low-power microprocessors and radio frequency transponders were just emerging, as were user-friendly artificial intelligence development platforms. One of the challenges presented by this project was to understand and leverage these relatively new technologies. That’s what engineers do all the time, but we had the added challenges of learning autism-related movement patterns, how the autistic children would handle the introduction of the monitors, and how to interact with these children as we validated our system’s accuracy.

Hal Greely Just One Question
Hal Greely Th’77 developed a wireless wearble body acceleration monitor for children with autism. Photograph courtesy of Hal Greely.

Working with the Dartmouth-Hitchcock Medical Center child psychologist who had introduced us to the need for this technology and provided access to volunteer test subjects and with Creare firmware engineers who developed a superb wearable movement monitor, I developed artificial neural network (ANN) software that recognized stereotypical movements hidden within normal movement activities. After testing with autistic kids, ANN processing of the device’s acceleration signals clearly demonstrated its potential utility for certain forms of stereotypy—particularly movements involving large muscle groups and whole body or bilateral movements.
—Hal Greeley Th’77

In my field of energy development, the hardest challenges involve a blend of technical, economic, environmental, community, and political issues. Often the technical challenge is the easiest part. The toughest project I’ve worked on would have to be the Point Arguello project and the design, permitting approval, construction, and startup of the Gaviota oil and gas plant. Located along the south-central California coast, in Santa Barbara County, the development had to account for stringent environmental standards and sensitive habitats, and faced vigorous political opposition from some segments of the community. We devised design features and construction techniques that limited emissions and minimized impacts to environmentally sensitive areas while dealing with the hydrogen sulfide content of the produced oil and gas (which posed safety and corrosion challenges). The project received development approval, with stringent permit and monitoring conditions, after extended delay, and then we had to complete a supplemental environmental impact assessment, with more conditions, before we could proceed. We overcame the technical challenges and built a high-quality facility, which performed as designed, after we dealt with the usual startup problems. While the project was a model for development in an environmentally sensitive area, the opposition continued to be contentious. It was a lesson in attempting to apply technical solutions to what are basically political issues and the difficulty in managing projects with regional or national benefits while posing local impacts.

Speaking more generally, there’s an extremely hard challenge that remains open: how to produce transportation fuels from cellulosic biomass in a system that is affordable, sustainable, and scalable.
—Will Fraizer ’78

The hardest engineering challenge I’ve ever faced is the project currently on my desk: the design of a new kind of ultra-high resolution medical imaging equipment with an analog front end that has to be very quiet. Those circuits have to coexist peacefully with a staggering amount of digital signal processing circuitry. Where about a dozen multi-channel 80-megahertz analog-to-digital converters bridge the analog and digital domains, things get particularly interesting. The printed circuit board on which it all sits is physically large enough that every piece of data moving on it has to be treated as an exercise in impedance and time-of-flight control. And when the signals all get where they’re going, they have to be treated as having come from completely different time domains, even if the clock that generated them all was the same to start out. At two gigahertz and about a few nanoseconds per foot for signal propagation in copper, physics will do that to you. It will allow surgeons and diagnostic-imaging radiologists to collaborate in real time while a surgery is being performed and see higher resolution images than the best equipment out there today. The result will be less-invasive surgery and more thorough resection of tumors. (Having had a very rare form of usually fatal cancer myself 12 years ago, part of the reason I took on this very difficult job was that I hold a grudge against cancer, and this is one of my personal ways of getting even.)


Eric Overton ’87 Th’89 says one of his greatest challenges was designing a video engine (see the test setup here) in 2008-09 that ended up in 3M’s pocket projector family. Photograph courtesy of Eric Overton.

But the technical details really aren’t the point of my answer. What I’d prefer to say is that if every three years I’m not taking on a job that’s the hardest I’ve ever done, I need to find another line of work. Part of the reason I founded Focus Embedded was to regularly do projects that have an extremely uncomfortable birthing process.
—Eric Overton ’87 Th’89

Today, we take it for granted to watch video streamed from the Internet on our PCs or smartphones. Back some 18 years ago, when most homes were connected to the Internet via a 56k modem, streaming video through that narrow pipe was unthinkable. Yet my team in QuickTime engineering at Apple was assigned the task to develop a new streaming video system that could deliver video using a 56k modem. The engineering requirements were strict: Video had to be compressed down to 28 kilobits per second (kbps) and audio to 16 kbps. I was leading the video compression work in our team, and it was the hardest engineering challenge I’ve ever faced. To picture it, at the required data rate, three minutes of video (including audio) had to be squeezed to less than 1 megabyte in file size, which is smaller than a single still picture that most smartphones generate today.

Jian Lu Just One Question
Jian Lu ’93, right, with Apple CEO Steven Jobs in 1999. Lu was a member of the engineering team that developed QuickTime streaming. Photograph courtesy of Jian Lu.

But we made it. In summer 1999 Apple released QuickTime streaming and QuickTime TV. Meeting that challenge was a major milestone and foundation for Apple in delivering Internet video. Today, billions of video streams are delivered to users on their PCs and mobile devices on a daily basis. In 2013 Apple received an Emmy Award in Technology and Engineering for its “eco-system for real time presentation of TV content to mobile devices without the use of specialized TV hardware.” Now I am chief technology officer of 360 video at Qihoo 360 Technology, based in Beijing, China.
—Jian Lu ’93

The hardest challenge I’ve ever faced was designing, building, and launching a complete mobile video messaging service for iOS and Android 100 percent by myself in 12 months. The individual problems were not complex when broken down, but the sheer magnitude of the task took quite a bit of intestinal fortitude, considering I had not really written any code myself in almost 20 years. That said, it was an experience that I wouldn’t trade for anything.

The second most challenging was figuring out how to reinvent the TV remote control and integrate it into the HTC One smartphone. There were several complex challenges, including building in an infrared emitter that worked in any hand position while hiding it beneath the power button so that we didn’t have to cut another hole in the aluminum unibody. We had to figure out how to make the setup of a TV and set-top box dead simple, how to get infrared codes for 100,000-plus TVs, set-top boxes, and audiovisual systems and TV show lineups for every cable and satellite provider in 25 launch countries. We did it in less than nine months. It was a true team effort that I merely had the privilege to lead, and it was a lot of fun.
—Bjorn Kilburn ’95

The hardest engineering challenge I ever faced was as an eighth-grade math teacher in Harlem, N.Y. I was struggling to make math feel relevant and important to my students in a way that engineering makes math feel relevant and important implicitly. My students were ages 13 to 15 and on average at a fifth- and sixth-grade level of math, just starting to get over the hump of some of the most challenging mathematical concepts we face growing up: negative numbers and fractions. It was a tough year, with my co-teacher changing mid-year (twice), a curriculum that felt hodge-podge at best, and low class morale. I wanted to come up with a way to show my students the significance that math had to me, in an engineering type of way. (Even as a student at Thayer, I ultimately identified far more with the problem-solving, idea-generating aspect of engineering than the numbers-crunching, formulaic foundations of engineering.) Time and again, I failed to show the truly inspirational part of math. No matter the presentation or the “real world” application, for the most part my classroom was a mess and the content wasn’t hitting home.

At the end of the year, I decided to get more personal with my students. I showed them my senior-year honors thesis, in which I designed an instrumented orthodontic retainer for biomedical purposes under the guidance of Assistant Professor Ryan Halter. Suddenly, my typically noisy room turned silent and 15 hands shot up with questions and comments. Some were obnoxious, eighth-grader comments, but others were about the specific process of my project, what inspired it, what problem I was trying to solve. It was my aha! moment of the year: My show-and-tell item that was meant as a personal aside ended up guiding my approach to my classroom for the remainder of the year. I had always wanted to bring engineering to my classroom, but I had tried to throw in engineering concepts and real-world applications of algebraic concepts and formulas after we learned the “boring stuff.” Now my kids were engaged because the problem felt real and engaging in its own right, independent of the numbers or formulas. It was still algebra—it was still about logic and problem solving—but it didn’t sound like that awful word al-ge-bra that my students hated.

So, after the state test, I had a math-free unit that had zero numbers. It was like a miniature ENGS 21, in which students got into groups for problem brainstorming, then solution brainstorming, then solution research, then solution selection, then solution mock-ups in big posters. It was a hit. I renamed my classroom “Logic and Problem Solving” on the spot. Algebra included, engineering inspired.
—Sam Worth ’13

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