The Case Of The Mysterious Driveline Noise

July 14, 2021 by Lewin Day 31 Comments

Spend enough time on the automotive classifieds and you’ll end up finding a deal that’s too good to pass up. The latest of these in one’s own case was a Mercedes-Benz sedan, just past its twentieth birthday and in surprisingly tidy condition. At less than $3,000, the 1998 E240 was too good to pass up and simply had to be seen.

The car in question. Clean bodywork is too tempting to resist, even if there are mechanical issues.

The car was clean, too clean for asking price. Of course, a test drive revealed the car had one major flaw – an annoying hum from the drivetrain that seemed to vary with speed. Overall though, mechanical problems are often cheaper and easier to fix than bodywork, so a gamble was taken on the German sedan. The first order of business was to diagnose and rectify the issue.

Characterise, Research, Investigate

The first step to hunting down any noise is to characterise it as much as possible. In this case, the noise was most noticeable when the car was traveling at speeds from 40 km/h – 60 km/h, present as a vibrational humming noise. The location of the noise source was unclear. Importantly, the noise varied with the speed of the car, raising in pitch at higher speeds and dropping as speeds decreased. Engine speed had no effect on noise whatsoever, and the noise was present regardless of gear selected in the transmission, including neutral. Continue reading “The Case Of The Mysterious Driveline Noise” →

Checking Up On Earth’s Sister Planet: NASA’s Upcoming Venus Missions

July 9, 2021 by Maya Posch 36 Comments

Even as we bask in the knowledge that our neighboring planet Mars is currently home to a multitude of still functional landers, a triplet of rovers and with an ever-growing satellite network as well as the first ever flying drone on another planet, our other neighboring planet Venus is truly playing the wallflower, with Japan’s Akatsuki orbiter as the lone active Venusian mission right now.

That is about to change, however, with NASA having selected two new missions that will explore Venus by the end of this decade. The DAVINCI+ and VERITAS missions aim to respectively characterize Venus’ atmosphere and map its surface in unprecedented detail. This should provide us information about possible tectonic activity, as well as details about the Venusian atmosphere which so far have been sorely missing.

Despite Venus being the closest match to our planet Earth, how is it possible that we have been neglecting it for so long, and what can we expect from future missions, including and beyond these two new NASA missions?

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Electric Land Speed Racing Can Be Lightning Fast

July 8, 2021 by Lewin Day 4 Comments

Land speed racing is a pursuit of ultimate speed above all else. Most cars typically run on huge, flat salt pans, and racers run flat out for miles in a straight line, attempting to push their machines to the limit. Like most motorsports, the history of land speed racing has traditionally been centred around internal combustion, but electric racers have long been out there chasing land speed records as well.

The Need For Speed

At the most famous land speed trials, such as Bonneville’s Speed Week, speed runs take place over miles and miles of open salt, with timing traps along the way to determine competitor’s speeds. These tracks are long enough that acceleration is of little concern, which is of great benefit to electric runners. Additionally, only one or two runs is required to set a record. This means that heavy batteries aren’t always needed, as the distance a competitor must travel is short, and even if the batteries are heavy, it doesn’t excessively affect top speed.

With an eye to that, land speed competitors in electric classes are typically classified into weight classes. This is due to the fact that bigger, heavier battery packs can deliver more current, and thus potentially have a performance advantage over lighter vehicles. Thus, typical classes run by most salt flats competitions involve the E1 class, which allows for vehicles under 1100 lbs, the E2 class, for vehicles up to 2200 lbs, and the E3 class, which is for anything 2200 lbs and above. The FIA also publish their own set of classes, again separated by weight, though to a much more granular degree.

Procedures for setting records vary depending on the venue and the record in question. Local records at salt venues like El Mirage can typically be broken with a single run faster than the standing record, while Bonneville Speed Week competitors must set a higher average speed across two runs on two consecutive days. FIA records differ again, and are perhaps the most stringent, requiring competitors to set a faster average across two runs in opposite directions, set within an hour of each other, to attempt to minimise the effect of wind on the result. Things can sometimes get confusing, as many FIA records, for example, are set at the Bonneville salt flats, but not actually in Speed Week competition or by Speed Week rules. Continue reading “Electric Land Speed Racing Can Be Lightning Fast” →

What’s Chia, And Why Is It Eating All The Hard Drives?

July 7, 2021 by Tom Nardi 102 Comments

At this point the average Hackaday reader is likely familiar with so-called “Proof of Work” (PoW) cryptocurrencies, such as Bitcoin, Ethereum, and Dogecoin. In the most basic of terms, these cryptocurrencies allow users to earn money by devoting computational power to the network. Unfortunately, it’s well past the point where your standard desktop CPU is moving enough bits to earn anything worthwhile. Individuals looking to turn a profit have therefore resorted to constructing arrays of high-end graphics cards for the express purpose of “mining” their cryptocurrency of choice.

These miners, combined with ongoing chip shortages, have ravaged the GPU market. Anyone who’s looked at building or upgrading a computer recently will know that new video cards are in short supply, and even old models that would otherwise be considered budget options, are commanding outrageous prices. In an effort to appease their core customers, NVIDIA has even introduced cryptocurrency-specific cards that lack video output. The hope was that professional miners would buy these Cryptocurrency Mining Processors (CMPs) instead of the traditional video cards, freeing up the latter for purchase by gamers. But due to the limited availability and relatively high cost of CMPs, they’ve done little to improve the situation.

Now if you don’t use your computer for gaming, this probably seems like a distant problem. You could even be forgiven for thinking of this as little more than two largely frivolous pursuits at loggerheads with each other. After all, in a community that still holds decades-old Thinkpads as the high water mark in portable computing, a certain ambivalence about cutting edge video cards is perhaps to be expected.

But there’s a new form of cryptocurrency on the rise which threatens more than just the hardcore gamers. With “Proof of Space” (PoS) cryptocurrencies, it’s not about having the fastest CPU or the highest number of GPUs; the commodity being traded is storage space, and the player with the most hard drives wins.

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Could Airships Make A Comeback With New Hybrid Designs?

July 1, 2021 by Lewin Day 101 Comments

Airships. Slow, difficult to land, and highly flammable when they’re full of hydrogen. These days, they’re considered more of a historical curiosity rather than a useful method of transport.

Hybrid Air Vehicles are a UK-based startup working to create a modern take on the airship concept. The goal is to create cleaner air transport for short-hop routes, while also solving many of the issues with the airship concept with a drastic redesign from the ground up. Their vehicle that will do all this goes by the name of Airlander 10. But is it enough to bring airships back to the skies?

A Hybrid Technology

Airlander 10 seen taking off during its first flight.

The Airlander 10 is not a lighter-than-air craft like traditional airships. Instead, the vehicle uses the buoyancy from its helium envelope to create only 60-80% of its lift. The rest of the left is generated aerodynamically by air passing over the eliptical shape of the airship’s body. This lift can also be further augmented by two diesel-powered ducted fans on the sides of the airship, which can pivot to assist with takeoff and landing. Two further fixed ducted fans on the rear provide the primary propulsion for the craft.

The hybrid approach brings several benefits over the traditional airship model. Chief among them is that as the Airlander 10 is heavier than air, it need not vent helium throughout flight to avoid becoming positively buoyant as fuel burns off, nor does it need to vent helium to land. However, it still maintains the capability to loiter for incredibly long periods in the sky as it needs to burn very little fuel to stay aloft. Reportedly, it is capable of five days when manned, and even longer durations if operated in an unmanned configuration. Using helium for lift instead of solely relying on engine thrust and wings means that it is much more fuel efficient than traditional fixed-wing airliners. The company’s own estimates suggest the Airlander 10 could slash emissions on short-haul air routes by up to 90%. The gentle take-off and landing characteristics also mean the vehicle doesn’t require traditional airport facilities, making it possible to operate more easily in remote areas, on grass, sand, or even water. Continue reading “Could Airships Make A Comeback With New Hybrid Designs?” →

Adding A Gentle Touch To Prosthetic Limbs With Somatosensory Stimulation

June 30, 2021 by Maya Posch 5 Comments

When Nathan Copeland suffered a car accident in 2004, damage to his spinal cord at the C5/C6 level resulted in tetraplegic paralysis. This left him initially at the age of 18 years old to consider a life without the use of his arms or legs, until he got selected in 2014 for a study at the University of Pittsburgh involving the controlling of a robotic limb using nothing but one’s mind and a BCI.

While this approach, as replicated in various other studies, works well enough for simple tasks, it comes with the major caveat that while it’s possible to control this robotic limb, there is no feedback from it. Normally when we try to for example grab an object with our hand, we are aware of the motion of our arm and hand, until the moment when our fingers touch the object which we’re reaching for.

In the case of these robotic limbs, the only form of feedback was of the visual type, where the user had to look at the arm and correct its action based on the observation of its position. Obviously this is far from ideal, which is why Nathan hadn’t just been implanted with Utah arrays that read out his motor cortex, but also arrays which connected to his somatosensory cortex.

As covered in a paper by Flesher et al. in Nature, by stimulating the somatosensory cortex, Nathan has over the past few years regained a large part of the sensation in his arm and hand back, even if they’re now a robotic limb. This raises the question of how complicated this approach is, and whether we can expect it to become a common feature of prosthetic limbs before long. Continue reading “Adding A Gentle Touch To Prosthetic Limbs With Somatosensory Stimulation” →

Kathleen Lonsdale Saw Through The Structure Of Benzene

June 29, 2021 by Kristina Panos 14 Comments

The unspoken promise of new technologies is that they will advance and enhance our picture of the world — that goes double for the ones that are specifically designed to let us look closer at the physical world than we’ve ever been able to before. One such advancement was the invention of X-ray crystallography that let scientists peer into the spatial arrangements of atoms within a molecule. Kathleen Lonsdale got in on the ground floor of X-ray crystallography soon after its discovery in the early 20th century, and used it to prove conclusively that the benzene molecule is a flat hexagon of six carbon atoms, ending a decades-long scientific dispute once and for all.

Benzene is an organic chemical compound in the form of a colorless, flammable liquid. It has many uses as an additive in gasoline, and it is used to make plastics and synthetic rubber. It’s also a good solvent. Although the formula for benzene had been known for a long time, the dimensions and atomic structure remained a mystery for more than sixty years.

Kathleen Lonsdale was a crystallography pioneer and developed several techniques to study crystal structures using X-rays. She was brilliant, but she was also humble, hard-working, and adaptable, particularly as she managed three young children and a budding chemistry career. At the outbreak of World War II, she spent a month in jail for reasons related to her staunch pacifism, and later worked toward prison reform, visiting women’s prisons habitually.

After the war, Kathleen traveled the world to support movements that promote peace and was often asked to speak on science, religion, and the role of women in science. She received many honors in her lifetime, and became a Dame of the British Empire in 1956. Before all of that, she honored organic chemistry with her contributions.

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