̽��ֱ�� of Cambridge - Hugh Hunt

Cambridge engineers bring historic Venn bowling machine back to life

sb726 — Sun, 09 Jun 2024 12:30:42 +0000

̽��ֱ��2-metre-high contraption bowled out players from the visiting Australian cricket team more than 100 years ago.

Refreeze the Arctic Foundation funds marine cloud brightening research

plc32 — Tue, 28 Feb 2023 00:30:00 +0000

̽��ֱ��Cambridge Centre will work in close cooperation with RAF and Delft ̽��ֱ�� of Technology Climate Institute (TUDCI) in the Netherlands on research to create methods for marine cloud brightening, a process that generates white cloud cover to increase the reflection of sunlight over the Arctic during the summer months and slow the melting of Arctic sea ice.

“We all know that cutting emissions is a non-negotiable requirement if we are to have a long-term climate that can sustain life as we know it. ̽��ֱ��problem is that we are moving too slowly and we are at serious risk of losing the Arctic summer sea ice, glaciers and other ecosystems which support cooler temperatures on Earth. Marine Cloud Brightening could potentially provide a means of safeguarding our climate whilst we get our greenhouse gas levels down,” said Dr Shaun Fitzgerald, Director of Research at the Centre for Climate Repair at Cambridge.

Cambridge engineers are hoping to mimic the way nature makes clouds. Storms at sea with crashing waves generate droplets of water which dry out to form salt crystals. Air currents carry the tiniest of these crystals high up to where the air is cool and moist, providing the nuclei around which white clouds can form.

“Maybe we can help nature to make whiter clouds by creating our own spray of sea water. If we can fine-tune the droplet size then we can make the clouds brighter and longer lasting," said Professor Hugh Hunt (Engineering Dynamics and Vibration at Cambridge).

Simultaneously TUDCI will offer its cloud physics, modelling and remote sensing expertise to derive the optimum combination of droplet size and number concentration needed for achieving the desired brightening effect.

RAF is confident that the cooperation between CCRC and TUDCI, where each research centre contributes following its fields of expertise, will accelerate the delivery of a Proof of Concept for Marine Cloud Brightening.

“We are extremely happy we can make this donation. Today is the start of a multi-year highly synergistic collaboration between two top universities. We realise our challenge is enormous and hope to expand this initiative into a global network,” RAF said.

̽��ֱ��Refreeze the Arctic Foundation is able to do its work thanks to a donation in memory of Hanns Walter Salzer Levi: linguist, historian, global citizen and philanthropist. ̽��ֱ��Foundation aims to develop emergency measures to combat global warming. It specifically supports research to make clouds whiter to reflect sunlight.

Marine Cloud Brightening is just one piece of research dedicated to tackling climate change at the ̽��ֱ�� of Cambridge, which created its Cambridge Zero climate initiative in 2019 to focus the power of one of the world’s top five global research universities on finding solutions to humanity’s most pressing problem.

̽��ֱ��Centre for Climate Repair at Cambridge and Refreeze the Arctic Foundation (RAF) signed a multi-year agreement to fund research methods for brightening clouds to combat climate change.

Marine Cloud Brightening could potentially provide a means of safeguarding our climate whilst we get our greenhouse gas levels down

Dr Shaun Fitzgerald

Dr M. Antoinette Nestor

Team members from Centre for Climate Repair at Cambridge, RAF and TUDCI Photos show: Front row from left to right: Dr Isabelle Steinke (TUDCI), Dr Shaun Fitzgerald (CCRC), Sir David King (CCRC), Professo

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Cambridge Science Festival returns for milestone 25th year

Anonymous — Fri, 25 Jan 2019 15:48:27 +0000

Celebrating its 25th year, the Festival runs for two weeks from 11-24 March and explores the theme of ‘discoveries’. An impressive line-up of acclaimed scientists includes microscopist Professor Dame Pratibha Gai, Astronomer Royal Professor Lord Martin Rees, 2018 Nobel prize winner Sir Gregory Winter, geneticist Dr Giles Yeo, statistician Professor David Spiegelhalter, engineer Dr Hugh Hunt, marine biologist and author Helen Scales, THIS Institute Director Professor Mary Dixon-Woods, futurist Mark Stevenson, and science presenter Steve Mould.

̽��ֱ��full programme is teeming with events ranging from debates, talks, exhibitions, workshops and interactive activities to films, comedy and performances, held in lecture theatres, museums, cafes and galleries around Cambridge. There are events for all ages and most are free.
With so many events on offer, audiences will be spoilt for choice. Some of the biggest events in week one include:

Is technology making us miserable? (11 March). Virtually every interaction we have is mediated through technology. Despite being ‘always-on’, are we any better off? Are we better connected? Or is technology making us miserable?
Putting radioactivity in perspective (12 March). Following a renewal of electricity generated by nuclear power, Professors Ian Farnan and Gerry Thomas, Imperial College London, discuss radioactivity in the natural world and the outcomes of decades of study on the health effects of radiation. Could these research outcomes reset attitudes towards radiation and the risks?
̽��ֱ��universe of black holes (13 March). Christopher Reynolds, Plumian Professor of Astronomy, describes how future research into black holes may yet again change our view of reality.
̽��ֱ��long-term perspective of climate change (14 March). Professors Ulf Büntgen, Mike Hulme, Christine Lane, Hans W Linderholm, Clive Oppenheimer, Baskar Vira, and Paul J Krusic discuss how we investigate past climate and the challenges we face in applying this to the policy-making process.
Catalytic activation of renewable resources to make polymers and fuels (15 March). Professor Charlotte Williams, ̽��ֱ�� of Oxford, discusses the development of catalysts able to transform carbon dioxide into methanol, a process which may deliver more sustainable liquid transport fuels in the future.
Does the mother ever reject the fetus? (15 March). Professor Ashley Moffett discusses fetal rejection and explores new discoveries that show that there are multiple mechanisms to ensure there is a peaceful environment in the uterus, where the placenta is allowed to grow and develop to support the fetus.

Top picks for the second week include:

Cambridge gravity lecture: Sir Gregory Winter (18 March). Sir Gregory is a molecular biologist and 2018 Nobel Laureate best known for his work on developing technologies to make therapeutic monoclonal antibodies. His research has led to antibody therapies for cancer, rheumatoid arthritis and multiple sclerosis.
Discoveries leading to new treatments for dementia (18 March). Professor of Clinical Neurosciences and Associate Director of the UK Dementia Research Institute, Giovanna Mallucci discusses how new research leading to insights into dementia and degenerative brain diseases may lead to new treatments.
Improving quality and safety in healthcare (19 March). THIS Institute Director Professor Mary Dixon-Woods looks at the challenges to improving quality and safety in healthcare and considers why it’s so hard to answer the question: Does quality improvement actually improve quality? With Dr Fiona Godlee, Editor in Chief of ̽��ֱ��BMJ.
Immunology: the future of medicine? (19 March) Professor Clare Bryant and a panel of Cambridge immunologists discuss how understanding disease triggers may enable entirely new approaches to treating and potentially preventing disease.
Polar ocean: the dead end of plastic debris (19 March). An estimated 80% of all the litter in our oceans is plastic, and a significant concentration of plastics debris is found in both polar oceans. ̽��ֱ��impact of this debris on the sensitive polar ecosystem could be profound. Pelagic marine ecologist Dr Clara Manno, British Antarctic Survey, explores the current research and existing situation in the polar regions.
Reluctant futurist (19 March). Old models for healthcare, education, food production, energy supply and government are creaking under the weight of modern challenges. Futurist Mark Stevenson looks at the next 30 years and asks, how can we re-invent ourselves for the future?
Adolescent mental health: resilience after childhood adversity (20 March). Adolescence is characterised by huge physiological changes as well as a rapid rise in mental health disorders. Around 45% of adolescent mental health problems are caused by childhood difficulties but fortunately not all who experience difficulties develop mental health disorders. Dr Anne-Laura van Harmelen discusses mechanisms that may help adolescents with a history of childhood difficulty to become more resilient.
Making algorithms trustworthy (21 March). Increasingly, algorithms are being used to make judgements about sensitive parts of our lives. How do we check how their conclusions were arrived at, and if they are valid and fair? Professor David Spiegelhalter looks at efforts to make algorithms transparent and trustworthy, using systems that make predictions for people with cancer as an example.
On the future: prospects for humanity (22 March). Professor Lord Martin Rees argues that humanity’s prospects on Earth and in space depend on our taking a different approach to planning for tomorrow.

This year’s Cambridge Science Festival also celebrates significant milestones in science, including the 200th anniversary of Cambridge Philosophical Society, Cambridge’s oldest scientific society, and 150 years since the publication of the modern Periodic Table.

Speaking ahead of the Festival, Dr Lucinda Spokes, Festival Manager, said: “We are tremendously proud of this year’s programme due to the variety of events and the calibre of our speakers from a range of institutions and industries.

“Alongside the meatier topics we have an array of events for all ages and interests across both weekends. We have everything from the science of perfumery and how your mood affects your taste, to a science version of 'Would I Lie to You?'

“One of my personal top picks are the open days at the various institutes and departments based at the West Cambridge site on Saturday 23 March. As always, the site is hosting some truly fascinating events, everything from the future of construction and how to make Alexa smarter, to how nanotechnology is opening up new routes in healthcare, and state-of-the-art approaches to low-cost solar energy and high-efficiency lighting solutions.

“A Festival of this magnitude would not be possible without the help from many people; we thank all our scientists, supporters, partners and sponsors, without whom the Festival would not happen. Most of all, we thank the audiences – there are more than 60,000 visits to the Festival events every year. We very much look forward to welcoming everyone from all ages to join us in March to explore the fabulous world of science.”

You can download the full programme here.

Bookings open on Monday 11 February at 11am.

This year’s Festival sponsors and partners are Cambridge ̽��ֱ�� Press, AstraZeneca, MedImmune, Illumina, TTP Group, Science AAAS, Anglia Ruskin ̽��ֱ��, Astex Pharmaceuticals, Cambridge Science Centre, Cambridge Junction, IET, Hills Road 6th Form College, British Science Week, Cambridge ̽��ֱ�� Health Partners, Cambridge Academy for Science and Technology, and Walters Kundert Charitable Trust. Media Partners: BBC Radio Cambridgeshire and Cambridge Independent.

̽��ֱ��2019 Cambridge Science Festival is set to host more than 350 events as it explores a range of issues that affect today’s world, from challenges around climate change policy, improving safety and quality in healthcare, and adolescent mental health, to looking at what the next 25 years holds for us and whether quantum computers can change the world.

We have everything from the science of perfumery and how your mood affects your taste, to a science version of 'Would I Lie to You?'

Dr Lucinda Spokes

Yes

Opinion: COP24: here's what must be agreed to keep warming at 1.5°C

Anonymous — Mon, 03 Dec 2018 12:56:38 +0000

̽��ֱ��Paris Agreement of 2015 has a central aim to keep global temperature rise this century well below 2°C above pre-industrial levels and to “pursue efforts” to limit the temperature increase even further to 1.5°C. This is an ambitious aim – global temperatures are rapidly approaching the 1.5°C target and the 2°C limit is not far away.

̽��ֱ��path to 1.5°C requires that the world achieve zero emissions before 2050. It is imperative, therefore, that we stop burning fossil fuels, known as mitigation. However, our present trajectory suggests we’re not on track. COP24 can’t take its eye off this ball –- there is no long-term plan that doesn’t include zero fossil-carbon emissions. ̽��ֱ��scientific consensus is that we need to reach “net zero” CO₂ emissions by 2050. But to tack closer to a scenario of 1.5°C warming, COP24 should set this target for 2035.

Black, observed temperatures; blue, probable range from decadal forecasts; red, retrospective forecasts; green, climate simulations of the 20th century. Credit: The Met Office

Carbon removal and non-CO₂ emissions

̽��ֱ��United Nations, in the IPCC Special Report on Global Warming of 1.5ºC has accepted that there isn’t any obvious pathway to zero emissions in such a short time frame, so they have pegged their hopes on NETs – Negative Emissions Technologies. These approaches include carbon capture and storage (CCS), which involves sucking CO₂ from the air and storing it deep underground.

Carbon removal along these lines is the second imperative for COP24 in Katowice. Globally we emit around 40 billion tonnes of CO₂ annually, so net zero CO₂ by 2050 will require CO₂ removal of this scale, starting immediately.

But CO₂ isn’t the only problem. We emit other greenhouse gases such as methane, nitrous oxide and chlorofluorocarbons (CFCs) which all contribute to climate change. Methane is on the rise and is 84 times more potent as a greenhouse gas than CO₂.

It comes from cows, and it leaks from oil wells and coal mines as “fugitive methane”. It is also seeping out of the melting permafrost in the Arctic. This is a worrying form of “positive feedback” where global warming causes the further release of gases that cause further warming.

Nitrous Oxide, which is 300 times more potent than CO₂, is rising too, caused by modern agriculture. And the concentration of refrigerant gases, such as CFCs, which are thousands of times more potent than CO₂, is not falling as fast as we’d hoped. So COP24 has a third imperative, to prevent the rise of non-CO₂ greenhouse gases. If we can stabilise non-CO₂ greenhouse emissions at present day levels we’ll be doing well, but concentrations are rising fast.

Limiting warming to 1.5°C or 2°C requires mitigation (energy efficiency and renewable generation) and CO₂ removal. Credit: MCC

Desperate times, desperate measures

All of this is going to be hard work. We’re failing to cut down our emissions, the technologies for NETs don’t exist at any meaningful scale, yet and there are no political drivers in place to enforce their deployment. There is also a real risk of a dramatic rise in methane in the near future. COP24 will have to consider emergency plans.

One such plan is very controversial. There are so-called “geoengineering” technologies which can be used to cause changes in global temperatures. One of these is Solar Radiation Management (SRM), which involves injecting tiny aerosol particles high in the atmosphere where they reflect sunlight into space.

We know from the eruption of Mount Pinatubo in 1991 that stratospheric aerosols caused a cooling of around 1°C over a year. ̽��ֱ��northern winter of 1992 saw a dramatic increase in sea ice and a stalling of glacial melting. SRM technologies exist and the first sun-dimming experiments are underway.

A proposed SRM technique which would inject sulphate aerosols into the atmosphere. Credit: Hugh Hunt/Wikimedia Commons, CC BY-SA

There is a realistic possibility that deploying SRM can buy us some time to enact the essential measures needed to stop warming at or before 1.5°C. ̽��ֱ��discussions at COP24 must keep all options on the table, and as unpalatable as geoengineering technologies might seem, their deployment may prove to be unavoidable.

̽��ֱ��indicators are all in the danger zone. We are seeing increasing Arctic temperatures, rapid loss of Arctic sea ice, reduced Arctic reflectivity, rapidly melting ice shelves and methane release from permafrost. These are leading to rapidly rising sea levels, coastal flooding and storm surges, increased hurricane and storm activity, dry and hot conditions conducive to wildfires, and drought and crop failure.

̽��ֱ��urgency for decisive action is the imperative for COP24. ̽��ֱ��UN must press on with four major strands for meeting the Paris 1.5°C target:

Reduce fossil carbon emissions.
Remove carbon from the atmosphere (NETs).
Halt the rise of emissions of non-CO₂ greenhouses cases (Methane, Nitrous oxide, CFCs).
Investigate techniques for geoengineering, including Solar Radiation Management.

All four of these must proceed simultaneously and in parallel. COP24 must make this perfectly clear. There is utmost urgency and no time to “wait and see”.

Hugh Hunt, Reader in Engineering Dynamics and Vibration, ̽��ֱ�� of Cambridge

This article is republished from ̽��ֱ��Conversation under a Creative Commons license. Read the original article.

As the COP24 climate summit begins in Poland, Hugh Hunt from Cambridge's Department of Engineering outlines just what it will take to limit global warming to 1.5°C, as outlined in the 2015 Paris Agreement.

Alto Crew on Unsplash

iceberg near body of water

Yes

Opinion: ̽��ֱ��Dambusters raid took place 75 years ago – here's how they made a bomb bounce

Anonymous — Wed, 16 May 2018 09:18:36 +0000

Sir Barnes Wallis was a genius engineer who designed a very special bomb during World War II. ̽��ֱ��idea was that it would bounce across water and destroy German dams along the Ruhr Valley, causing massive flooding and damage to water and hydroelectricity supplies.

Partly thanks to the 1955 film ̽��ֱ��Dam Busters, the story behind Operation Chastise, which took place on May 16 and 17 in 1943, has become a familiar war time tale. But Wallis’s actual working calculations were lost (fittingly perhaps, in a flood in the 1960s). So what do we know about the complex science behind the bouncing bombs?

We know that the Germans considered their dams to be a potential target for their enemies, and placed torpedo nets in front of the structures to protect them. And to bust a dam, Wallis realised that peppering it with lots of small bombs wouldn’t work. It would be the difference between throwing a handful of sand at a window, and then doing the same with a rock.

Wallis figured that to do serious damage, a single four-tonne bomb had to be detonated right up against the dam wall at a depth of about 30ft below the water. In those days, high altitude bombing accuracy wasn’t good enough to deliver such a bomb bang on target. ̽��ֱ��idea of bouncing it across the water towards the dam like a skimming stone was inspired.

In early experiments a few things became clear. First, for the bomb to bounce it had to be spinning – with backspin. Just like that a delicate backspin dropshot in tennis, which causes the ball to hover just over the net.

Wallis worked out that a bomb with backspin would be levitated by what is known as the Magnus effect countering the downward pull of gravity and ensuring that it struck the surface of the water gently. If the bomb hit the water too hard, it would detonate prematurely, causing damage to the aircraft above, but no damage to the dam.

Spin therefore meant that the bombs could be delivered from a manageable height. Flying at 60ft was already dangerously low, but without backspin the Lancaster bombers would have to have flown even lower and faster.

In Wallis’ earliest experiments he worked with marbles and golf balls and it was obvious that his bomb would be spherical. But because it was easier to manufacture cylindrical bombs, a spherical wooden casing was strapped to the cylinders to make them round.

However, when scaled up to full size, the casing on the spherical bombs would break apart on impact with the water. It didn’t take long to establish that the spherical casing was unnecessary and that the bare cylinder would bounce just as effectively.

Spin doctor

Unlike a sphere however, cylinders will only bounce if they bounce straight. This is the second good reason for spinning the bomb, because spin keeps the axis of the cylinder horizontal so that it hits the water squarely. Just like for the spinning planet Earth, the gyroscopic effect of the spinning cylinder stabilises the axis of spin.

Wallis found yet another key benefit of backspin. ̽��ֱ��bomb couldn’t just smash into the dam wall at 240mph, as it would detonate prematurely and do no significant damage. So he made sure the bomb landed just short of the dam – but because it was still spinning, it curved down gently towards the dam wall. By the time it reached the required depth it was right up against the dam where it would cause maximum damage.

Finally, Wallis needed to know how much explosive to use. He did small-scale tests on models and then worked out how to scale up the amount of explosive to deal with a dam which is 120ft high, and ideally would have loaded his bombs with 40 tonnes of explosive. In the event (there’s only so much one plane can carry) he could only use four tonnes, so as well as the dark conditions, low altitude and enemy fire, precision was key.

(For our own bouncing bomb experiment in 2011, we found that 50 grams of explosive would completely demolish a 4ft dam, so our 30ft version would need 160kg. We used 180kg just to be sure … and it was totally wrecked.)

Following trials on water in Dorset and Kent, the actual raid took place in the early hours of May 17 1943, with 19 Lancaster bombers flying out of RAF Scampton in Lincolnshire. After a three hour flight, the first plane lined itself up on the Möhne dam, flying at 240mph and at that dangerously low altitude of 60ft.

̽��ֱ��bomb was released about half a mile in front of the dam, bounced five or six times and sank just short of the wall. At the required depth of 30ft the pressure of water triggered the explosion right next to the dam wall. In all, five planes had to drop their bombs before the first dam was breached.

̽��ֱ��raid was dangerous, many lives were lost, and its effect on the course of the war is still debated. One thing we can surely agree on however, 75 years later, is that Wallis is rightly remembered as a genius engineer.

This article was originally published on ̽��ֱ��Conversation. Read the original article.

Hugh Hunt from Cambridge's Department of Engineering - who recreated the Dambusters raid in 2011 - discusses how engineers made a bomb bounce 75 years ago in an article for ̽��ֱ��Conversation.

Picture reproduced by permission of Windfall films

A plane drops a bouncing bomb at Mackenzie, British Columbia, where researchers successfully reconstructed the Dambusters mission of World War II.

Yes

Opinion: How we can make super-fast hyperloop travel a reality

ljm67 — Fri, 13 Jan 2017 16:00:06 +0000

Across Europe and parts of Asia, travellers can enjoy some of the fastest rail services in the world. From Málaga to Madrid, Tokyo to Osaka, high-speed electric trains condense the travel times between major hubs by racing along at some 300kph. ̽��ֱ��fastest commercial service in the world is the Shanghai maglev – short for magnetic levitation, the method of propulsion it uses to glide along its tracks as rapidly as 430kph.

Of course, air travel is still much faster: an Airbus A380 aircraft has a cruising speed of over 1,000kph. But at a time when reducing emissions is a top priority across the globe, there’s an urgent demand for cleaner, more energy-efficient alternatives – especially in the US, which is by far the world’s biggest user of air travel, with almost 800m passengers each year. Enter, the Hyperloop – a train-like technology which has the potential to match air travel for speed.

Hyperloop is the brainchild of US business magnate Elon Musk. First proposed in 2013, the Hyperloop system consists of “pods”, which are suspended inside a tube by magnetic levitation and propelled using a linear electric motor. ̽��ֱ��environment inside the tube is almost a complete vacuum, allowing the pods to travel at great speeds without being slowed by air resistance. ̽��ֱ��tubes themselves can be placed underground, or run above ground, elevated by columns.

̽��ֱ��race begins

Musk originally intended the Hyperloop to cover the 600km route from Los Angeles to San Francisco at an average speed of about 960kph, reducing what’s currently a 12-hour train journey to just 35 minutes. Although funding has since been channelled into a bullet train service for this route, the idea of the hyperloop has attracted interest elsewhere.

̽��ֱ��wealthy city-state of Dubai has agreed to conduct a feasibility study for a 150km link with Abu Dhabi. There’s also a proposal to connect Vienna with Budapest and Bratislava. And US start-up Hyperloop One recently announced a shortlist of 35 potential hyperloop test projects, which included proposals for routes linking Sydney with Melbourne, London with Edinburgh and Mumbai with Delhi.

While these developments have sparked much excitement, some remain sceptical about whether they can work in the real world.

Too fast to function?

Hyperloop pods are designed to reach their top speed of 1,220kph (slightly less than the speed of sound) in about 70 seconds, when accelerating at 0.5G (the “G” refers to “G-force”, which is how we measure acceleration).

To put this in context, at 1G we are pushed into the back of our seat with a force equal to our body weight – it would be uncomfortable. But the acceleration of an aircraft during takeoff is typically around 0.4G, and most people are happy with that.

We also experience G-forces when we go around a curve. This “centrifugal force” is what flings you from side to side on fairground rides. Again, about 0.5G is the limit for comfort. Travelling at speeds of 1,220kph sets the minimum curve radius to about 23km, which means that the track has to be pretty straight. It must be very level, too, because vertical hills and bumps also give rise to G-forces.

With the right site, these constraints could be manageable. ̽��ֱ��real challenge for hyperloop will be dealing with earth movements. In all large-scale engineering, allowances are made for thermal expansion, ground water and seismic activity – things that make the ground shift around. Normally, these aren’t too much of a problem. There are expansion joints in bridges and pavements, and even when subsidence causes cracks to appear in a wall, we shrug our shoulders and say “so what?”.

But movement in the hyperloop track could cause real problems, when the pods are travelling at such high speeds. That’s why Musk favours a track on columns, so that it can be adjusted and realigned in the event of ground movement. Indeed, we already do this kind of realignment with conventional railway tracks: the rails on sleepers are loosely supported on ballast and regular “tamping” ensures that the track is kept straight.

With such demanding specifications, actually constructing a hyperloop will not be cheap. But the days of aircraft and ships are numbered, unless we can find a way to power them with electricity or hydrogen fuel. Perhaps we could even learn to live with nuclear-powered ships. Hyperloop offers a novel vision of the future of long-distance travel – one that might just catch on.

Hugh Hunt, Reader in Engineering Dynamics and Vibration, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

Trains are getting increasingly faster, but as Professor Hugh Hunt from the Department of Engineering explains, the 'super-fast hyperloop' could soon see them matching air travel fo speed.

Camilo Sanchez

Concept art of Hyperloop inner works

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Licence type:

Attribution-ShareAlike

Re-enacting the first night of television, 80 years on

Anonymous — Wed, 02 Nov 2016 00:44:15 +0000

Television’s Opening Night: How the Box was Born will be screened on BBC Four on 2 November 2016, 80 years after Britain first experienced the phenomenon of a live television broadcast. No recordings of the 1936 broadcast remain, so Windfall Films sought to piece together and re-enact every aspect of the historic day, with experts Dallas Campbell and Professor Danielle George, as well as Dr Hugh Hunt from Cambridge's Department of Engineering.

At the home of BBC television, London’s Alexandra Palace, the stage was set for a competition between rival technologies after the Television Committee, set up by the government in 1934, could not choose between the two systems tendered and opted to trial both.

Thus Scotsman Logie Baird’s 240-line mechanical transmission of moving pictures and sound along existing wireless technology was in one studio on the first night, and Marconi’s Emitron electronic 405-line system was in another. ̽��ֱ��former used a spinning disc and the latter a cathode ray receiver. ̽��ֱ��ultimate aim was the same – to create a scanned image that could be reproduced by the cathode ray tube of a television screen.

Through the toss of a coin, Logie Baird’s system went first, which was perhaps fitting as he had demonstrated a working television system a decade previously and succeeded in transmitting images from London to Scotland and across the Atlantic.

Logie Baird used a mechanical spinning image device, the Nipkow Disk, which had been invented in 1884. His genius was to perfect the transmission of images over the air waves. When a bright light shone through one hole at a time in this spinning disk it caused a tiny spot of light to scan across the presenter’s face. Hence the camera was known as ‘the flying spot’, explains Hunt, who is a Fellow of Trinity College.

This light was picked up by a photocell and the reflected light intensity relayed by wireless to televisions in people’s homes – as there were only around 300 sets in 1936, many people flocked to Selfridges to watch the phenomenon in their showroom.

̽��ֱ��‘flying spot’ moved from left to right across the presenter’s face to cover the entire screen using 240 lines. ̽��ֱ��receiving TV set needed a signal to identify the end of each line. ̽��ֱ��Baird system incorporated a black band at the end of each line so that the TV set would get a signal to know when to start the next line. Likewise at the end of each screen there were a few blank lines so that the TV would know when to shift the beam back up to the top of the screen.

Together with engineering students Charlie Houseago (Trinity), Anna Maria Kypraiou (Newnham) and Arthur Tombs (Queens’), and colleagues in the Engineering Department, Hunt recreated a scaled-down version of the flying spot camera for the documentary.

As Logie Baird found, synchronizing the television’s flying spot with the camera’s spot was a huge challenge.

Hunt said: "Our disc is 600mm in diameter with 60 holes spinning at 900rpm. This creates a 60 line image at 15 frames per second, not quite up to the original 240 lines at 25 frames per second but we didn’t have the 20 years of development time that Logie Baird had. Still, our image quality was quite remarkable."

̽��ֱ��official trial of the two systems was soon halted as Marconi’s EMI system was much more flexible and versatile than Logie Baird’s flying spot – it could film in natural daylight for instance – and the future of television was set. Until the flat-screen technologies of the 1990s, television cameras were essentially derived from the EMI system and televisions in people’s homes were cathode ray tubes.

"As remarkable an invention as it was I don’t think the flying spot was ever going to last," said Hunt. "But that doesn’t detract from Logie Baird’s genius and vision. He could see that people would be captivated by television. His system was developed and perfected over decades at a time when there were no alternatives."

Television’s Opening Night: How the Box was Born will be broadcast on BBC Four at 9pm on Wednesday 2 November.

Originally published on the Trinity College website.

Cambridge researchers and students have recreated John Logie Baird’s cumbersome ‘flying spot’ camera for a documentary about the first live scheduled BBC television broadcast on 2 November 1936.

Our image quality was quite remarkable.

Hugh Hunt

BBC/Windfall Films/George Woodcock

Hugh Hunt examines the disc of the recreated flying spot camera

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Opinion: How does a bike stay upright? Surprisingly, it’s all in the mind

Anonymous — Tue, 24 May 2016 15:23:54 +0000

It’s as easy as riding a bike … or so the saying goes. But how do we manage to stay upright on a bicycle? If anyone ventures an answer they most often say that it’s because of the “gyroscopic effect” – but this can’t be true.

Put simply, the gyroscopic effect occurs because a spinning wheel wants to stay spinning about its axis, just as a spinning top or even planet Earth stay aligned to their spin axes. While motorcyclists with their big, heavy, fast-spinning wheels may notice the gyro effect, a modest everyday cyclist won’t because the wheels are much lighter and at a leisurely riding speed they don’t spin quickly enough.

If a pedal bicycle did stay upright because of the gyroscopic effect then any novice getting on a bike could just push off and the bike – and the effect – would do the rest. ̽��ֱ��simple truth is that you have to learn how to ride, just as you must learn how to walk. Riding a bike is all in the mind.

Imagine you had to ride along a perfectly straight line on a perfectly flat path. Easy, surely. Well, no. It’s virtually impossible to ride along a narrow straight line just as it’s really hard to walk perfectly along a straight line, even when you’re not drunk. Try it.

Now attempt this little experiment: stand on the ball of one foot, using your arms to balance. It’s quite hard. But now try hopping from one foot to the other. It is much easier to keep your balance. It’s called running. What your brain has learned to do is to make a little correction every time you take off so that if, say, you’re falling to the right, then you’ll hop a bit to the left with the next step.

It’s the same with pedalling a bike. When riding, you’re always making tiny corrections. If you are falling to the right, then you subconsciously steer a bit to the right so that your wheels move underneath you. Then, without thinking, you steer back again to stay on the path.

This “wobbling” is perfectly normal. It is more obvious among beginners (mostly children) who wobble around quite a lot, but it may be almost imperceptible in an expert cyclist. Nevertheless, these little wobbles are all part of the process and explain why walking – or riding – on a dead straight line is so hard because you can’t make those essential little side-to-side corrections.

Grand designs

There are some really clever bits in bicycle design to make riding a bike easier, too. Most important is the fact that the steering column (the “head tube”) is tilted so that the front wheel makes contact with the ground at a point that lies behind where the steering axis intersects with the ground. ̽��ֱ��distance between these two points is called “the trail”.

Bicycle dimensions. By Rishiyur1, own work

̽��ֱ��trail really helps to stabilise a bike when you’re riding with no hands because when you lean to the right, say, the force at the contact point on the pavement will turn the front wheel to the right. This helps you to steer effortlessly and it allows for hands-free steering by leaning slightly left or right.

But people have built bikes with vertical head tubes and they are perfectly rideable, too. In fact, it’s quite hard to make a bike you can’t ride, and many have tried.

That’s because keeping a bike upright is largely to do with you and your brain – something that’s easy to prove. Try crossing your hands over, for example. You will not even be able to get started, and if you switch hands while you’re riding, be warned, you will fall off instantaneously – something that wouldn’t happen if it were the gyroscopic effect keeping you upright.

Clowns and street performers ride bikes with reverse-geared steering. It takes months of practice to learn how to ride a bike like this, and it’s all about unlearning how to ride a normal bike. It’s amazing how the brain works.

̽��ֱ��gyroscopic effect

But what about the gyroscopic effect I referred to earlier? Surely it helps a bit? Well, no it doesn’t … unless you’re going pretty fast. There is a well-known demonstration that seems to show how a bike wheel is really affected by the gyroscopic effect but if you do the sums you can show that the effect is nowhere near strong enough to hold you up when you’re riding a bike.

To prove that the gyro effect is unimportant I built a bike with a second, counter-rotating front wheel. I’m not the first to have done this – David Jones built one in 1970. We both had the same idea. Essentially, the backward spinning wheel cancels out the gyroscopic effect of the front wheel, proving that it doesn’t matter and that the only thing keeping you upright is your brain. It’s also a really fun experiment that anyone can do.

So what’s the best way to learn to ride? Well, watching children learning to ride with trainer wheels distresses me because every time one of the stabilisers touches the ground it is an unlearning experience. To cycle, your brain has to learn to wobble, so take off the trainer wheels – and the more you wobble the quicker you’ll learn. Cycling really is all in the mind.

Hugh Hunt, Reader in Engineering Dynamics and Vibration, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Hugh Hunt (Department of Engineering) discusses how we manage to stay upright on a bicycle.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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