Cycling and bikes

The bicycle is a tremendously efficient means of transportation. In fact cycling is more efficient than any other method of travel! The one billion bicycles in the world are a testament to its effectiveness. The engine for this efficient mode of transport is the human body. Because bodies are fueled by food, diet plays an important role in how the body performs. Different muscle groups and types provide the power. Genetic inheritance, intensive training, and a competitive drive help top athletes push the boundaries of endurance and speed on the bicycle. European Cyclists' Federation - http://www.ecf.com/

City bikes

These have lighter, smoother tyres and a slightly
modified mountain bike frame, with a more upright riding
position specially adapted for urban cycling. They
are often sold with mudguards and other utility
fittings as standard. Hybrids can cope with a wide
range of terrain and are a good option for everyday
trips. They are less suitable for sports or specialist
cycling.

Road or racing bikes

Drop handlebars, light wheels and thin slick tyres
make these the most efficient and fastest bikes
for the road. However, they are more prone to
punctures and do not cope well with poor
surfacing. You may also find the riding position
less comfortable than a hybrid for everyday
journeys.

Mountain bikes

Originally designed for off-road cycling, the wide
range of gears, suspension and good
manoeuvrability have made these equally popular
with urban riders. However, the knobbly tyres
make pedalling harder, so it’s advisable to fit city
tyres if you rarely go off-road. The riding
position may not be as comfortable as a hybrid
for everyday journeys and items such as
mudguards and carrier racks will usually need to
be fitted separately.

Folding bikes

These are specifically aimed at those who want to
combine cycling with other modes of transport.
They are ideal for bus or train commuters who
want to cycle to and from the station. However,
their small wheels and often limited range of gears
make them only really suitable for relatively short
urban journeys.

Hybrid electric vehicles

Hybrid electric vehicles (HEV) work through a combination of an internal combustion engine, an electric motor and a bank of batteries. This combination simply reduce the engine size and boost acceleration with an electric motor. Currently, most vehicles can be driven either with the engine, the electric motor solely, or both the engine and electric motor simultaneously providing power.

Depending on the degree of hybridisation HEVs can be broadly categorised into:

• MILD HEVS (functionality: start/stop + boost), e.g. Honda Civic
• FULL HEVs (functionality: start/stop + boost + pure electric drive), e.g. Toyota Prius

HEVs have several advantages over conventional vehicles:

• Regenerative braking capability helps minimize energy loss and recover the energy used to slow down or stop a vehicle.
• Engines can be sized to accommodate average load, not peak load, which reduces the engine’s weight.
• Fuel efficiency is greatly increased.
  
• Emissions are greatly decreased.
• Special lightweight materials are used to reduce the overall vehicle weight of HEVs.

Hybrid cars - http://www.hybridcars.com/

Some of the most recent additions to the expanding fleet of marketed Hybrid Vehicles are the Lexus RX 400 hybrid, the Ford Escape Hybrid, the Honda Accord Hybrid, and the Honda Civic. The Chevrolet Silverado and the GMC Sierra are available in limited quantities in several states, and are the first hybrid electric pickup trucks.

CAD/CAM Systems

Acronym for computer-aided design/computer-aided manufacturing, computer systems used to manufacture products and design. The term CAD/CAM implies that an engineer can use the system both for designing a product and for controlling manufacturing processes. For example, once a design has been produced with the CAD component, the design itself can control the machines that construct the part.

Free Mechanical Engineering CAD/CAM Software

ProgeCAD LT, SolidCAM, G-Simple, BobCAD, Powerstation, FeatureMill3D, CodeShark Lite, e NC, SprutCAM, KZX, QPS, VX

Spectroscopy

Spectroscopy is the study of the interaction between radiation (electromagnetic radiation, or light, as well as particle radiation) and matter. Spectrometry is the measurement of these interactions and an instrument which performs such measurements is a spectrometer or spectrograph. A plot of the interaction is referred to as a spectrum.

Historically, spectroscopy referred to a branch of science in which visible light was used for the theoretical study of the structure of matter and for qualitative and quantitative analyses. Recently, however, the definition has broadened as new techniques have been developed that utilise not only visible light, but many other forms of radiation.

Spectroscopy is often used in physical and analytical chemistry for the identification of substances through the spectrum emitted from or absorbed by them. Spectroscopy is also heavily used in astronomy and remote sensing. Most large telescopes have spectrometers, which are used either to measure the chemical composition and physical properties of astronomical objects or to measure their velocities from the Doppler shift of their spectral lines.

Nature of radiation measured

The type of spectroscopy depends on the physical quantity measured. Normally, the quantity that is measured is an amount or intensity of something.

• Electromagnetic spectroscopy involves interactions with electromagnetic radiation, or light. Ultraviolet-visible spectroscopy is an example.
• Electronic spectroscopy involves interactions with electron beams. Auger spectroscopy involves inducing the Auger effect with an electron beam.
• Mechanical spectroscopy involves interactions with macroscopic vibrations, such as phonons. An example is acoustic spectroscopy, involving sound waves.
• Mass spectroscopy involves the interaction of charged species with magnetic and/or electric fields, giving rise to a mass spectrum. The term "mass spectroscopy" is deprecated in favour of mass spectrometry, for the technique is primarily a form of measurement, though it does produce a spectrum for observation.

Measurement process

Most spectroscopic methods are differentiated as either atomic or molecular based on whether or not they apply to atoms or molecules. Along with that distinction, they can be classified on the nature of their interaction:

• Absorption spectroscopy uses the range of the electromagnetic spectra in which a substance absorbs. This includes atomic absorption spectroscopy and various molecular techniques, such as infrared spectroscopy in that region and nuclear magnetic resonance (NMR) spectroscopy in the radio region.
• Emission spectroscopy uses the range of electromagnetic spectra in which a substance radiates (emits). The substance first must absorb energy. This energy can be from a variety of sources, which determines the name of the subsequent emission, like luminescence. Molecular luminescence techniques include spectrofluorimetry.
• Scattering spectroscopy measures the amount of light that a substance scatters at certain wavelengths, incident angles, and polarization angles. The scattering process is much faster than the absorption/emission process. One of the most useful applications of light scattering spectroscopy is Raman spectroscopy.

Interesting articles about spectroscopy

http://www.spectroscopymag.com/
http://ioannis.virtualcomposer2000.com/spectroscope/

PLOTEUS

A Portal on Learning Opportunities Throughout the European Space

A skilled and mobile workforce is a key element in the European Union objective to become the most competitive and dynamic knowledge-based economy in the world. By providing access to information systems and services on learning opportunities across Europe, Ploteus contributes to reach this objective.

Ploteus is accessible through Your Europe portal.

Jewel bearing

A jewel bearing is a bearing which an unlubricated metal shaft spins in a jewel-lined pivot hole. The hole is typically shaped like a torus and is slightly larger than the shaft diameter. In operation, the shaft tilts slightly so as to contact the jewel pivot hole at two opposite points. The shaft rolls inside of the bearing rather than sliding. As the shaft rolls, the center precesses. It was invented by Nicolas Fatio de Duillier, Peter Debaufre and Jacob Debaufre in 1704 who took out an English patent to control their idea. Originally natural jewels were used, such as sapphire, ruby and garnet. In the early 1900s a process to make synthetic sapphire and ruby (crystalline aluminum oxide also known as corundum) was invented, making jeweled bearings practical and much less expensive.

Jewel bearings were used widely for mechanical (escapement) watches, where their low and predictable friction improved watch accuracy. A typical mark of watch quality was a note such as "17 jewels". More jewel bearings often meant better precision. Some makers added non-functional or unnecessary jewels to give the impression of accuracy. Some watches had as many as 100 jewels, most of them of no use. A typical "fully jeweled" time-only watch has two cap jewels, two pivot jewels, an impulse jewel for the balance wheel, two pivot jewels, two pallet jewels for the pallet fork, and two pivot jewels each for the escape, fourth, third and center wheels. Modern electronic watches achieve accuracy entirely separate from the friction of the mechanism, but early quartz watches used jewels to increase battery life, and high-grade quartz watches use jewels to reduce friction and wear.

Today, jewel bearings are used widely in sensitive measuring equipment.

The advantages of jewel bearings include high accuracy, very small size and weight, low friction, predictable friction including good temperature stability, ability to operate without lubrication and in corrosive environments. Disadvantages include limited availability/applicability in medium and large bearing sizes and capacities, and friction variations if the load is not axial.

Jewel bearings are typically used for very small applications such as high-precision instruments. Bearing bores are typically less than 1 mm and typically support loads of under 1 gram; large jewel bearings are as large as 10 mm and support loads up to about 500 g.

Historically, jewel pivots were made by grinding. Modern jewel pivots are often made using high-powered lasers, chemical etching, and ultrasonic milling.

Jewel bearings are known for their low breakaway friction and highly consistent moving friction. The jewel surfaces are very hard and durable and can maintain smoothness over decades of use, thus reducing friction variability. Flexure bearings have even lower variability, but also have a more limited range of motion.

http://www.swissjewel.com/jewel_bearing_applications.htm

Nanomaterials

A unique aspect of nanotechnology is the vastly increased ratio of surface area to volume present in many nanoscale materials which opens new possibilities in surface-based science, such as catalysis. A number of physical phenomena become noticeably pronounced as the size of the system decreases. These include statistical mechanical effects, as well as quantum mechanical effects, for example the “quantum size effect” where the electronic properties of solids are altered with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached. Additionally, a number of physical properties change when compared to macroscopic systems. One example is the increase in surface area to volume of materials. This catalytic activity also opens potential risks in their interaction with biomaterials.

Nanotechnology can be thought of as extensions of traditional disciplines towards the explicit consideration of these properties. Additionally, traditional disciplines can be re-interpreted as specific applications of nanotechnology. This dynamic reciprocation of ideas and concepts contributes to the modern understanding of the field. Broadly speaking, nanotechnology is the synthesis and application of ideas from science and engineering towards the understanding and production of novel materials and devices. These products generally make copious use of physical properties associated with small scales.

Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances become transparent (copper); inert materials become catalysts (platinum); stable materials turn combustible (aluminum); solids turn into liquids at room temperature (gold); insulators become conductors (silicon). Materials such as gold, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nanoscales. Much of the fascination with nanotechnology stems from these unique quantum and surface phenomena that matter exhibits at the nanoscale.

Nanosize powder particles (a few nanometres in diameter, also called nanoparticles) are potentially important in ceramics, powder metallurgy, the achievement of uniform nanoporosity and similar applications. The strong tendency of small particles to form clumps ("agglomerates") is a serious technological problem that impedes such applications. However, a few dispersants such as ammonium citrate (aqueous) and imidazoline or oleyl alcohol (nonaqueous) are promising additives for deagglomeration.

http://www.nanotech-now.com/current-uses.htm

Fossil fuel

Coal

Coal is especially abundant and by itself could sustain the current energy consumption of the entire planet for 60 years. This was the fuel that launched the industrial revolution and has continued to grow in use; China, which already has many of the worlds most polluted cities, was in 2007 building about two coal fired power plants every week. Coal is the fastest growing fossil fuel and its large reserves would make it a popular candidate to meet the energy demand of the global community, short of concerns of global warming. With the Fischer-Tropsch process it is possible to make liquid fuels such as diesel and jet fuel from coal.

Oil

It is estimated that there may be 57 ZJ of oil reserves on Earth (although estimates vary from low of 8 ZJ, consisting of currently proven and recoverable reserves, to a maximum of 110 ZJ) consisting of available, but not necessarily recoverable reserves, and including optimistic estimates for unconventional sources such as tar sands and oil shale. Current oil consumption is at the rate of 0.18 ZJ per year.

There is growing consensus that peak oil production may be reached in the near future, resulting in severe oil price increases. A 2005 French Economics, Industry and Finance Ministry report suggested a worst case scenario that could occur as early as 2013. There are also theories that peak of the global oil production may occur in as little as 2-3 years. The ASPO predicts peak year to be in 2010. Some other theories present the view that it has already taken place in 2005.

Sustainability

There is a broad consensus among scientists that we are not close to running out of fossil fuels. Despite this abundance, political considerations over the security of supplies, environmental concerns related to global warming and sustainability might move the world's energy consumption away from fossil fuels. The concept of peak oil shows that we have used about half of the available petroleum resources, and predicts a decrease of production.

A government led move away from fossil fuels would most likely create economic pressure through carbon emissions trading and green taxation. Some countries are taking action as a result of the Kyoto Protocol, and further steps in this direction are proposed. For example, the European Commission has proposed that the energy policy of the European Union should set a binding target of increasing the level of renewable energy in the EU's overall mix from less than 7% today to 20% by 2020.

RoboCup Junior Slovakia 2007

The twelfth year of the Contest in building and programming robots for secondary and elementary schools, RoboCup Junior Slovakia 2007 took place in the creative environment of Combined secondary school of electrical technology in a little town Stará Turá in Western Slovakia on March 1st and 2nd. The contest consisted of several categories:

Thematic Robot Building and Programming, Robotic Soccer, RoboRescue, and Robotic Dance. The contest served as the RoboCup Junior national selection round. More than 30 teams from the whole Slovakia participated. The contest was organized by the Slovak Society of Electronics.

Robot Building and Programming

Ten teams worked for four hours on projects on the theme "Ecology". The teams presented their projects to the Jury, and the audience. The teams used the LEGO robotics sets as the platform - both RCX and NXT sets were allowed and used.

Robotic Soccer

The robotic soccer with infrared ball was played using the standard international RoboCup Junior rules.

Both one-on-one and two-on-two categories were played, a tournament with all teams playing against all teams.

Seven teams participated in one-on-one category, 4 teams participated in two-on-two category.

The matches were spectacular and on a comparable level to the world championship. The winning teams are advancing to the World Finals (provided they will acquire funding)

RoboRescue

In the popular contest of RoboRescue according to the international rules of RoboCup Junior attracted 9 participating teams. See the full version in Slovak for the results.

Robot Dance

The most spectacular and creative category attracted four teams. The performances were very cute, see the photo galleries below.

See robotika.sk for information on other robotics contests.

Leonardo Da Vinci

Practical inventions and projects



Leonardo was master of mechanical principles. He utilised leverage and cantilevering, pulleys, cranks, gears, including angle gears and rack and pinion gears; parallel linkage, momentum, centripetal force and the aerofoil.

Because Leonardo's inventions date from an era before the issue of patents, it is impossible to say with any certainty how many or even which of his inventions passed into general and practical use, and thereby had impact over the lives of many people. Among those inventions that are credited with passing into general practical use are the strut bridge, the automated bobbin winder, the machine for testing the tensile strength of wire and the lens-grinding machine pictured at right.

In the lens-grinding machine, the hand rotation of the grinding wheel operates an angle-gear, which rotates a shaft, turning a geared dish in which sits the glass or crystal to be ground. A single action rotates both surfaces at a fixed speed ratio determined by the gear.

Bridges and hydraulics

Leonardo's study of the motion of water led him to design machinery that utilised its force.
Among his projects in Florence was one to divert the course of the Arno, in order to flood Pisa. Fortunately, this was too costly to be carried out. He also surveyed Venice and came up with a plan to create a movable dyke for the city's protection against invaders.

In 1502, Leonardo produced a drawing of a single span 240 m (720-foot) bridge as part of a civil engineering project for Ottoman Sultan Beyazid II of Istanbul. The bridge was intended to span an inlet at the mouth of the Bosphorus known as the Golden Horn. Beyazid did not pursue the project, because he believed that such a construction was impossible. Leonardo's vision was resurrected in 2001 when a smaller bridge based on his design was constructed in Norway. On 17 May 2006, the Turkish government decided to construct Leonardo's bridge to span the Golden Horn.

War machines

In Leonardo's notebooks there is an array of war machines which includes a tank to be propelled by two men powering crank shafts. Although the drawing itself looks quite finished, the mechanics were apparently not fully developed because, if built as drawn, the tank, with a lot of effort, might be made to rotate on the spot, but would never progress in a forward direction. In a BBC documentary, a military team built the machine and found it not working, until they changed only one of the gears. It is believed that Da Vinci deliberately left this error in the design, in order to prevent it from being put to practice by unauthorized people.
Another machine, propelled by horses with a pillion rider, carries in front of it four scythes mounted on a revolving gear, turned by a shaft driven by the wheels of a cart behind the horses.

Leonardo's notebooks also show cannons which he claimed "to hurl small stones like a storm with the smoke of these causing great terror to the enemy, and great loss and confusion."

He also designed an enormous crossbow. Following his detailed drawing, one was constructed by the British Army, but could not be made to fire successfully.

Leonardo was the first to sketch the wheel-lock musket c. 1500 AD (the precedent of the flintlock musket which first appeared in Europe by 1547), although the Chinese of the earlier 14th century had used a flintlock 'steel wheel' in order to detonate land mines.

Flight

The desire to fly is expressed in the many studies and drawings. His later journals contain a detailed study of the flight of birds and several different designs for wings based in structure upon those of bats which he described as being less heavy because of the impenetrable nature of the membrane. On January 3, 1496 he unsuccessfully tested a flying machine he had constructed.

One design that he produced shows a helicopter to be lifted by a rotor powered by four men. It would not have worked since the body of the craft itself would have rotated in the opposite direction to the rotor.

While he designed a number of man powered flying machines with mechanical wings that flapped, he also designed a parachute and a light hang glider which could have flown.

Physics Java Applets

Mechanics

• Kinematics of 1 D uniformly accelerated motion
• Projectile motion
• Addition of forces
• Motion under different kinds of force
• Inclined plane
• Drop an object onto a moving trolley
• Work and energy
• Interrupted Pendulum
• Conical pendulum
• SHM and uniform circular motion
• An oscillator
• Torque
• Rotational inertia
• Translation and Rotation

Light & Wave

• Lens effects
• Lens effect due to ripples
• Refraction through a prism
• Transverse travelling wave
• Longitudinal travelling wave
• Transverse stationary wave
• Resonance on a string
• Formation of beats
• Interference of water waves I
• Interference of water waves II
• Multiple sources interference
• Diffraction of water waves (opening)
• Diffraction of water waves(obstacle)
• Diffraction of water waves(corner)
• Polarizers

E & M

• Simple electric circuit
• Shunt and multiplier
• Magnetic force
• Electromagnetic induction (motional emf)
• Transformer
• Inductor
• Root-mean-square values
• RC dc charging circuit
• RCL series a.c. circuit
• Lissajous figures

Electronics

• Not gate
• NPN common emitter amplifier

http://www.ngsir.netfirms.com/englishVersion.htm

Electrical injuries

Electrical injuries can be caused by a wide range of voltages but the risk of injury is generally greater with higher voltages and is dependent upon individual circumstances.

Alternating current (AC) and Direct Current (DC) electrical supplies can cause a range of injuries including:

• Electric shock
• Electrical burns
• Loss of muscle control
• Thermal burns

There are posters that give first aid procedur es for Electric Shock and Emergency action, including for burns.

More detailed technical information on electrical injury is given in the standard BS PD 6519 "Guide to the effects of current on human beings and livestock - Part 1: General aspects".
Electric shock

A voltage as low as 50 volts applied between two parts of the human body causes a current to flow that can block the electrical signals between the brain and the muscles. This may have a number of effects including:

• Stopping the heart beating properly
• Preventing the person from breathing
• Causing muscle spasms

The exact effect is dependent upon a large number of things including the size of the voltage, which parts of the body are involved, how damp the person is, and the length of time the current flows.

Electric shocks from static electricity such as those experienced when getting out of a car or walking across a man-made carpet can be at more than 10,000 volts, but the current flows for such a short time that there is no dangerous effect on a person. However, static electricity can cause a fire or explosion where there is an explosive atmosphere (such as in a paint spray booth).
Electrical burns

When an electrical current passes through the human body it heats the tissue along the length of the current flow. This can result in deep b urns that often require major surgery and are permanently disabling. Burns are more common with higher voltages but may occur from domestic electricity supplies if the current flows for more than a few fractions of a second.
Loss of muscle control

People who receive an electric shock often get painful muscle spasms that can be strong enough to break bones or dislocate joints. This loss of muscle control often means the person cannot ‘let go’ or escape the electric shock. The person may fall if they are working at height or be thrown into nearby machinery and structures.
Thermal burns

Overloaded, faulty, incorrectly maintained, or shorted electrical equipment can get very hot, and some electrical equipment gets hot in normal operation. Even low voltage batteries (such as those in motor vehicles) can get hot and may explode if they are shorted out.

People can receive thermal burns if they get too near hot surfaces or if they are near an electrical explosion. Other injuries may re sult if the person pulls quickly away from hot surfaces whilst working at height or if they then accidentally touch nearby machinery.

A single low voltage torch battery can generate a spark powerful enough to cause a fire or explosion in an explosive atmosphere such as in a paint spray booth, near fuel tanks, in sumps, or many places where aerosols, vapours, mists, gases, or dusts exist.

Voltage and frequency

Europe and most other countries in the world use a voltage which is twice that of the US. It is between 220 and 240 volts, whereas in Japan and in most of the Americas the voltage is between 100 and 127 volts.

The system of three-phase alternating current electrical generation and distribution was invented by a nineteenth century creative genius named Nicola Tesla. He made many careful calculations and measurements and found out that 60 Hz (Hertz, cycles per second) was the best frequency for alternating current (AC) power generating. He preferred 240 volts, which put him at odds with Thomas Edison, whose direct current (DC) systems were 110 volts. Perhaps Edison had a useful point in the safety factor of the lower voltage, but DC couldn't provide the power to a distance that AC could.

When the German company AEG built the first European generating facility, its engineers decided to fix the frequency at 50 Hz, because the number 60 didn't fit the metric standard unit sequence (1,2,5). At that time, AEG had a virtual monopoly and their standard spread to the rest of the continent. In Britain, differing frequencies proliferated, and only after World War II the 50-cycle standard was established. A mistake, however.

Not only is 50 Hz 20% less effective in generation, it is 10-15% less efficient in transmission, it requires up to 30% larger windings and magnetic core materials in transformer construction. Electric motors are much less efficient at the lower frequency, and must also be made more robust to handle the electrical losses and the extra heat generated. Today, only a handful of countries (Antigua, Guyana, Peru, the Philippines, South Korea and the Leeward Islands) follow Tesla’s advice and use the 60 Hz frequency together with a voltage of 220-240 V.

Originally Europe was 120 V too, just like Japan and the US today. It has been deemed necessary to increase voltage to get more power with less losses and voltage drop from the same copper wire diameter. At the time the US also wanted to change but because of the cost involved to replace all electric appliances, they decided not to. At the time (50s-60s) the average US household already had a fridge, a washing-machine, etc., but not in Europe.

The end result is that now, the US seems not to have evolved from the 50s and 60s, and still copes with problems as light bulbs that burn out rather quickly when they are close to the transformer (too high a voltage), or just the other way round: not enough voltage at the end of the line (105 to 127 volt spread !).

Note that currently all new American buildings get in fact 240 volts split in two 120 between neutral and hot wire. Major appliances, such as virtually all drying machines and ovens, are now connected to 240 volts. Mind, Americans who have European equipment shouldn't connect it to these outlets. Although it may work on some appliances, it will definitely not be the case for all of your equipment. The reason for this is that in the US 240 V is two-phase, whereas in Europe it is single phase.

http://users.pandora.be/worldstandards/electricity.htm