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Drones more damaging than bird strikes to planes, study finds

As part of a multi-institution Federal Aviation Administration (FAA) study focused on unmanned aerial systems, researchers at The Ohio State University are helping quantify the dangers associated with drones sharing airspace with planes.

Last week, a research team from the Alliance for System Safety of UAS through Research Excellence (ASSURE) released a report concluding that drone collisions with large manned aircraft can cause more structural damage than birds of the same weight for a given impact speed.

The FAA will use the research results to help develop operational and collision risk mitigation requirements for drones. ASSURE conducted its research with two different types of drones on two types of aircraft through computer modeling and physical validation testing.

Kiran D’Souza, assistant professor of mechanical and aerospace engineering at Ohio State, led the engine ingestion portion of the first-of-its-kind study.

“Even small unmanned aircraft systems can do significant damage to engines,” D’Souza said.

Reports of close calls between drones and airliners have surged. The FAA gets more than 100 sightings a month of drones posing potential risks to planes, such as operating too close to airports. The FAA estimates that 2.3 million drones will be bought for recreational use this year, and the number is expected to rise in coming years.

Unlike the soft mass and tissue of birds, drones typically are made of more rigid materials. The testing showed that the stiffest components of the drone — such as the motor, battery and payload — can cause the most damage to the aircraft body and engine.

Led by Gerardo Olivares, director of Wichita State University’s National Institute for Aviation Research, the team evaluated the potential impacts of drones weighing 2.7 to 8 pounds on a single-aisle commercial transport jet and a business jet.

They examined collisions with the wing leading edge, the windshield, and the vertical and horizontal stabilizers. The windshields generally sustained the least damage and the horizontal stabilizers suffered the most serious damage. The severity levels ranged from no damage to failure of the primary structure and penetration of the drone into the airframe.

An expert in gas turbine dynamics, Ohio State’s D’Souza conducted computer simulations to evaluate the potential damage of a drone entering a generic mid-sized business jet engine, including damage to fan blades, the nacelle and the nosecone.

The simulations revealed that the greatest damage and risk occurs during takeoff, since the fan is operating at the highest speed at this phase of flight. The location of the drone’s contact on the fan is a key parameter, with the most damage occurring when the impact is near the blade tip.

According to D’Souza, the next step is the development of a representative commercial jet engine model for ingestion simulations, as well as full-scale testing to verify and validate the simulations. The team is planning additional research on engine ingestion in collaboration with engine manufacturers, as well as additional airborne collision studies with helicopters and general aviation aircraft.

The researchers concluded that drone manufacturers should adopt “detect and avoid” or “geo-fencing” capabilities to reduce the probability of collisions with other aircraft.

Story Source:

Materials provided by Ohio State University. Original written by Matt Schutte

Traffic signal countdown timers lead to improved driver responses

Countdown timers that let motorists know when a traffic light will go from green to yellow lead to safer responses from drivers, research at Oregon State University suggests.

The findings are important because of mistakes made in what traffic engineers call the “dilemma zone” — the area in which a driver isn’t sure whether to stop or keep going when the light turns yellow.

A traffic signal countdown timer, or TSCT, is a clock that digitally displays the time remaining for the current stoplight indication — i.e., red, yellow or green.

Widely adopted by roughly two dozen countries around the world, traffic signal countdown timers are not used in the U.S. Crosswalk timers for pedestrians are allowed, but TSCTs are prohibited by the Department of Transportation.

“When you introduce inconsistencies — sometimes you give drivers certain information, sometimes you don’t — that has the potential to cause confusion,” said David Hurwitz, transportation engineering researcher in OSU’s College of Engineering and corresponding author on the study.

There were more than 37,000 traffic fatalities in the United States in 2016. Around 20 percent of those occurred at intersections, he said.

It’s not known exactly how many U.S. intersections are signalized because no agency does a comprehensive count, but the National Transportation Operations Coalition estimates the number to be greater than 300,000.

A significant percentage of those feature fixed-time signals, which are recommended in areas with low vehicle speed and heavy pedestrian traffic.

Traffic signal countdown timers work well at fixed-time signals, Hurwitz said, but they may not be practical for actuated signals; at those intersections, he said, a light typically changes only one to four seconds after the decision to change it is made — not enough time for a countdown timer to be of value.

In this study, which used a green signal countdown timer, or GSCT, in Oregon State’s driving simulator, the clock counted down the final 10 seconds of a green indication.

A subject pool of 55 drivers ranging in age from 19 to 73 produced a data set of 1,100 intersection interactions, half of which involved a GSCT. The presence of the countdown timer increased the probability that a driver in the dilemma zone would stop by an average of just over 13 percent and decreased deceleration rates by an average of 1.50 feet per second.

“These results suggest that the information provided to drivers by GSCTs may contribute to improved intersection safety in the U.S.,” Hurwitz said. “When looking at driver response, deceleration rates were more gentle when presented with the countdown timers, and we did not find that drivers accelerated to try to beat the light — those are positives for safety. Drivers were significantly more likely to slow down and stop when caught in the dilemma zone. The results in the lab were really consistent and statistically convincing.”

The findings, published recently in Transportation Research Part F: Traffic Psychology and Behaviour, build on a 2016 paper in Transportation Research Part C: Emerging Technologies.

The earlier results, which arose from a related research project, showed drivers were more ready to go when the light turned green at intersections with a red signal countdown timer, which indicates how much time remains until the light goes from red to green. The first vehicle in line got moving an average of 0.82 seconds more quickly in the presence of a timer, suggesting an intersection efficiency improvement thanks to reduction in time lost to startups.

The papers comprised dissertation work by then Ph.D. student Mohammad Islam, who now works for a Beaverton, Oregon-based company, Traffic Technology Services. Amy Wyman, an OSU Honors College undergraduate who completed her degree in 2017, collaborated on the publication.

TTS, whose chief executive officer, Thomas Bauer, is also an OSU College of Engineering alumnus, has developed a cloud-computer-connected countdown timer for the automotive industry.

Several cars in the German luxury carmaker Audi’s 2017 lineup already feature the timer, which can be viewed both on the instrument panel and via a heads-up display. The system is currently operational in several U.S. cities including Portland.

Unlike the traffic-signal-mounted timers, the onboard clocks are allowed in the U.S.

Story Source:

Materials provided by Oregon State University

A drone for last-centimeter delivery

A new drone developed at EPFL uses cutting-edge technology to deliver parcels weighing up to 500 grams. The device will never get stuck in traffic, it’s programmed to avoid obstacles, and it can reach destinations on steep or uneven terrain. Its protective cage and foldable design mean that it can be carried around in a backpack and used in total safety.

With a drone, things like letters, medicine, first-aid supplies and food can be delivered quickly, cheaply and autonomously without having to worry about traffic, blocked roads or a lack of roads. Some companies will surely come to rely on these drones. And engineers will be called on to develop ever more sophisticated models to keep pace with this new facet of e-commerce.

The drone, which has been designed in EPFL’s Laboratory of Intelligent Systems with funding of NCCR Robotics, is equipped with several innovations that make it particularly safe, autonomous and easy to transport.

The unique idea here is that the drone becomes the package that wraps around the cargo before flight, just like a mail package. The foldable carbon-fiber cage protects the drone and the cargo in case of a collision or fall. What’s more, the recipient can catch the drone mid-flight without being injured by the propellers, which are located within the structure and have a safety system so that they stop when the cage is opened.

The origami-inspired design means that the frame can be folded and unfolded in a single movement. It can be flattened in just a few seconds, reducing the drone’s volume by 92% so that it can easily be slipped inside a backpack.

An accurate, self-flying drone

The drone — a multicopter with four propellers — can take off and land vertically, which enhances its accuracy. And it can carry a package weighing up to 500 grams over a distance of 2 kilometers.

The drone contains specially designed self-flying software to program the delivery. A flight plan is created to ensure it avoids obstacles such as trees and buildings. The drone can then be tracked in real time on a tablet or smartphone. And once the package has been delivered, the drone makes its way back on its own. The device also has a safety system to prevent it from being hacked.

“This project is a work in progress — in addition to strengthening its ability to detect and avoid objects, we are exploring possibilities to increase the drone’s payload capacity and enhance its autonomy, “says Przemyslaw Kornatowski, who developed the drone. “Throughout the summer, we tested our human-friendly, drone-delivery system on the EPFL campus, delivering items to people over 150 test flights.” The drone will also have a parachute to increase its safety in the event of a breakdown.

Story Source:

Materials provided by Ecole Polytechnique Federale de Lausanne (EPFL).

A Study of the Influence of the Microstructure of One Type of Bitumen Grade on the Performance as a Binder

The adhesive properties bitumen has been studied extensively due to its relevance in road construction. Further understanding on the stage of failure associated with temperature and strain rates, overall performance of bitumen as an adhesive is of high importance to the construction industry.

Dr. Hartmut Fischer and Dr. Steven Mookhoek from TNO Technical Sciences in the Netherlands studied the effects and performance of the microstructure of various samples of bitumen with comparable PEN grade (Q8, Esso, Nynas, Shell, Total and Venezuelan). The work which is published in the peer-reviewed journal, Construction and Building Materials achieved this feat by making use of a newly designed micro-tensile testing (µ-DDT) to evaluate the adhesive performance of the bituminous binders with the use of a glass-silica half ball configuration in the tensile test setup. Results were coupled the observed features in the microstructure, as determined by use of an atomic force microscopy and differential thermal analysis on the bitumen samples.

The newly evolved micro-tensile test was found to be powerful in determining adhesive/cohesive forces between the formed bonds of different bitumen samples with silica at certain strain rates, with a clear view of the adhered area from residual materials on the half-ball silica surface.

Outcomes from atomic force microscopy indicated that the bitumen samples have comparable microstructural features with the presence of perpetua and peri phase microstructure, all except for the bitumen specimen of Nynas.

In differential thermal analysis it was observed that an equal mixture of the bitumen samples with glass spheres and with Wigras filler material had a loss in thermal transition due to reduction in asphaltenes inside the bitumen samples after addition of filler particles. From this observation, asphaltenes can be said to be a strong requirement for good adhesion. The Nynas bitumen sample in contrast to other bitumen samples did not show the formation of a catana phase, and resulted in a poor adhesion to the glass-silica surface.

A two-step response was recorded with appreciate to normal force, cavitation and cohesive rupture for all bitumen specimens with a prolonged peri phase or a co-continuous micro structure except for that of Nynas, leading to a strong correlation between measurable bond strength and that of the catana/peri phase area.

In addition, it was shown that a stronger adhesive-cohesive force was determined to be found in bitumen specimen with an extended two phase microstructure compared with those with absent two phase microstructure or that of a shielded peri microstructure which depicts the importance of the peri phase on the bonding behaviors of the tested binders.

This study provides a new technique to further our knowledge on performance of bitumen as binding agent which might produce advanced and higher performance materials for pavements and highway applications.

Journal Reference

Hartmut R. Fischer, Steven D. Mookhoek. A Study of the Influence of the Microstructure of One Type of Bitumen Grade on the Performance as a Binder, Construction and Building Materials

How does LiDAR work?

The principle behind LiDAR is really quite simple. Shine a small light at a surface and measure the time it takes to return to its source. When you shine a torch on a surface what you are actually seeing is the light being reflected and returning to your retina. Light travels very fast – about 300,000 kilometres per second, 186,000 miles per second or 0.3 metres per nanosecond so turning a light on appears to be instantaneous. Of course, it’s not! The equipment required to measure this needs to operate extremely fast. Only with the advancements in modern computing technology has this become possible.

The actual calculation for measuring how far a returning light photon has travelled to and from an object is quite simple:

Distance = (Speed of Light x Time of Flight) / 2

The LiDAR instrument fires rapid pulses of laser light at a surface, some at up to 150,000 pulses per second. A sensor on the instrument measures the amount of time it takes for each pulse to bounce back. Light moves at a constant and known speed so the LiDAR instrument can calculate the distance between itself and the target with high accuracy. By repeating this in quick succession the insturment builds up a complex ‘map’ of the surface it is measuring. With airborne LiDAR other data must be collected to ensure accuracy. As the sensor is moving height, location and orientation of the instrument must be included to determine the position of the laser pulse at the time of sending and the time of return. This extra information is crucial to the data’s integrity. With ground based LiDAR a single GPS location can be added for each location where the instrument is set up.

Generally there are two types of LiDAR detection methods. Direct energy detection, also known as incoherent, and Coherent detection. Coherent systems are best for Doppler or phase sensitive measurements and generally use Optical heterodyne detection. This allows them to operate at much lower power but has the expense of more complex transceiver requirements. In both types of LiDAR there are two main pulse models: micropulse and high-energy systems. Micropulse systems have developed as a result of more powerful computers with greater computational capabilities. These lasers are lower powered and are classed as ‘eye-safe’ allowing them to be used with little safety precautions. High energy systems are more commonly used for atmospheric research where they are often used for measuring a variety of atmospheric parameters such as the height, layering and density of clouds, cloud particles properties, temperature, pressure, wind, humidity and trace gas concentration.

Most LiDAR systems use four main components:

Lasers :

Lasers are categorised by their wavelength. 600-1000nm lasers are more commonly used for non-scientific purposes but, as they can be focused and easily absorbed by the eye, the maximum power has to be limited to make them ‘eye-safe’. Lasers with a wavelength of 1550nm are a common alternative as they are not focused by the eye and are ‘eye-safe’ at much higher power levels. These wavelengths are used for longer range and lower accuracy purposes. Another advantage of 1550nm wavelengths is that they do not show under night-vision goggles and are therefore well suited to military applications.

Airborne LiDAR systems use 1064nm diode pumped YAG lasers whilst Bathymetric systems use 532nm double diode pumped YAG lasers which penetrate water with much less attenuation than the airborne 1064nm version. Better resolution can be achieved with shorter pulses provided the receiver detector and electronics have sufficient bandwidth to cope with the increased data flow.

Scanners and Optics :

The speed at which images can be developed is affected by the speed at which it can be scanned into the system. A variety of scanning methods are available for different purposes such as azimuth and elevation, dual oscillating plane mirrors, dual axis scanner and polygonal mirrors. They type of optic determines the resolution and range that can be detected by a system.

Photodetector and receiver electronics :

The photodetector is the device that reads and records the signal being returned to the system. There are two main types of photodetector technologies, solid state detectors, such as silicon avalanche photodiodes and photomultipliers.

Navigation and positioning systems :

When a LiDAR sensor is mounted on a mobile platform such as satellites, airplanes or automobiles, it is necessary to determine the absolute position and the orientation of the sensor to retain useable data. Global Positioning Systems provide accurate geographical information regarding the position of the sensor and an Inertia Measurement Unit (IMU) records the precise orientation of the sensor at that location. These two devices provide the method for translating sensor data into static points for use in a variety of systems.

New coastal highway route for Reunion

Description

Work on a new €1.7 billion coastal road is underway around France’s Reunion Island

This new 12.3km highway (Route du Littoral) will have three lanes in each direction when it is complete in 2018.

The new offshore highway connects Saint Denis, the administrative capital of La Réunion, with La Possession.

This is a significant project and involves the use of a large fleet of heavy machinery.

Manitowoc, Grove and Potain cranes are working together to help build the new coastal road around Reunion Island.

In all large 16 cranes of various types are being used on the island, which is located to the east of Madagascar.

Meanwhile equipment from Enerpac is playing a key role in constructing a viaduct.

One of the most complex aspects of the work is the construction of the 5.4km viaduct on columns rising out from the Indian Ocean.

This is being built so that it will be able to withstand 144km/h hurricane winds as well as waves of up to 10m in height.

The project is being carried out by French consortium Bouygues Travaux Publics, VINCI Construction Grands Projets, Dodin Campenon Bernard and Demathieu Bard Construction.

Once complete, this will be the most expensive road/km funded by France.

The crane fleet in use on the project comprises two Potain MD 485B M20s, two MDT 368 As, one MD 560 B, a Potain k5-50C, a Manitowoc 12000E-1 crawler crane, seven

Grove all-terrain cranes and two Grove rough-terrain cranes. Installation of the Potain cranes was completed in September of 2015, including setting up and erecting the jibs.

The 16 cranes were supplied by contractors Vinci Construction Grands Projets and Bouygues TP which own some of the units and Grues Levages Investissements (GLI) which also provided cranes for this high-profile project on rental contracts.

GLI is Manitowoc’s official French dealer for Reunion Island, Mayotte and Mauritius and has invested heavily in supplying the cranes for this project.

The Origin of Manning’s Equation

How an unemployed accountant changed civil engineering

Ever wonder about the origin of Manning’s equation? Well, even if you haven’t it’s still interesting. This well-known equation achieved its notoriety in a way parallel to many other things in our modern consumer society. Through what some may call typical but accidental word-of-mouth marketing techniques. But not by its inventor.

The equation was named after an Irishman (actually born in France in 1816) Robert Manning. He was 73 when he introduced the equation to the Institution of Civil Engineers in Ireland. He died eight years later.

Here’s what’s interesting… he never stepped a foot in a fluid mechanics class or had an engineering degree. He worked for his uncle as an accountant until the Irish famine caused him to lose his job in 1845. But a year later he was hired on at the expanding Irish Public Works Department in the drainage division. While one thing led to another, he was appointed Chief Engineer 1874 and held this position until retirement in 1891. He taught himself hydraulics.

He admired folks like Chezy, Darcy, Kutter and a few other H&H pioneers. Apparently his mass detestation for complex mathematical formulae was the driving force behind his passion for simplicity. He tinkered with as many as seven other hydraulic formulae for open channel flow created by his colleagues in an effort to boil it all down to this equation:

(C later turns into the reciprocal of Kutter’s n)

But this equation had a serious problem… a cube root. Computing a number to the 2/3rds power was not easy in the late 1800’s. So Manning trashed it and created one that didn’t have a cube root extraction:

(m is barometric pressure)

It is this equation that he named after himself in 1895 but with little applause. Barometric pressure, really?

Meanwhile, others in his field liked his first rendition of ten years earlier. Manning had noted that the reciprocal of C somehow closely corresponded with an n-value determined by Ganguillet and Kutter. As time passed authors began to reference the original formula as Manning’s equation but with Kutter’s n-value. The cubed root was still a major issue among practicing civil engineers so it wasn’t very popular.

But in 1918, Manning’s equation went viral thanks to Horace W. King. Does the Handbook of Hydraulics ring a bell? King not only suggested exchanging Manning’s K for Kutter’s n, he tabulated the two-thirds power of numbers over the range of 0.01 to 10 and added it to the 1^st edition of Handbook of Hydraulics. Perhaps it was this table that overcame the greatest difficulty in using Manning’s equation and made it as famous as it is today. An equation that Manning himself rejected years earlier and that is baked into most modern hydrology software features.

All told, it took circumstances, an Irish famine, an unemployed accountant and a University of Michigan professor to create this favorite tool that today’s practicing civil engineer refuses to give up. Manning’s equation is still the most widely used. Over the last century many new modern formulae have been developed but nothing has changed in the real world. Well, perhaps for a just a few years. Here’s what Manning’s equation looked like in the late 1950’s, early 60s.

Significant milestone achieved on Shanghai-Nantong rail bridge

A ceremony was held to mark a significant milestone in the construction of the Shanghai-Nantong Bridge in the city of Nantong, east China’s Jiangsu Province, on October 22, 2017, reports chinanews.com.

Crews have finished building the first arch which will support the massive bridge over the Yangtze River.

The double-decker bridge will eventually run just over 11-kilometers above the Yangtze River.

It will support six lanes of vehicle traffic running in both directions on the top deck.

The lower deck will allow train traffic to run in both directions, providing a key link between Shanghai and the city of Nantong.

Construction on the Shanghai-Nantong Bridge began in March, 2014.

Officials anticipate the bridge will eventually be completed by mid-2022.

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Lotus Temple in New Delhi, India

The Lotus Temple in New Delhi, India, is a Bahá’í House of Worship completed it 1986.

Notable for its flowerlike shape, it serves as the Mother Temple of the Indian subcontinent and has become a prominent attraction in the city.

The Lotus Temple has won numerous architectural awards and been featured in hundredsof newspaper and magazine articles.

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Millau Viaduct

Millau viaduct holds the world record for the tallest bridge, culminating at 343 metres (higher than the Eiffel tower), 2460 metres long and touching the bottom of the Tarn valley in only 9 places.

Conceived by the French engineer Michel Virlogeux and designed by the English architect Lord Norman Foster, it fits perfectly into the naturally intact and grandiose landscape : a very thin slightly curved steel roadway supported by stays gives it the appearance of a huge yacht and the ensemble rests on 7 very slender pillars.

Millau viaduct constitutes the most spectacular link in La Méridienne: the A75 motorway, linking Clermont-Ferrand with Béziers and Narbonne, which is the least congested and cheapest route between Paris and the Mediterranean…

Resting to the north on the Lévézou and to the south on the Causse du Larzac, Millau viaduct crosses the Tarn valley, a few hundred yards from Peyre, one of the 10 “plus beaux villages de France” (most beautiful villages in France) found in the département of the Aveyron.

It is, of course, very close to Millau, “ville d’Art et d’Histoire”, outdoor sports capital and gateway to the Gorges Tarn.

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