Mirror Writing
Mirror writing is formed by writing in the direction that is the reverse of the natural way for a given language, such that the result is the mirror image of normal writing: it appears normal when it is reflected in a mirror. It is sometimes used as an extremely primitive form of cipher. The most common modern usage of mirror writing can be found on the front of ambulances, where the word "AMBULANCE" is often written in very large mirrored text, so that drivers see the word the right way around in their rear-view mirrorand understand why they hear a loud siren behind them.
Research suggests that the ability to do mirror writing is probably inherited and caused by atypical language organisation in the brain . It is not known how many people in the population inherited the ability of mirror writing (an Australian researcher estimates the proportion to be 1 in 6500). Half of the children of people with the ability inherited it. There are more left-handed mirror writers than right-handed ones, probably because left-handed people tend to have atypical language centres in their brain.
Leonardo da Vinci is famous for having written most of his personal notes in mirror, only using standard writing if he intended his texts to be read by others. There are two popular theories on why he did this. Leonardo da Vinci was left-handed, causing the ink to smudge easily if he wrote in standard writing. He may also have wanted to protect his ideas from theft or hide them from the Roman Catholic Church (with whom his scientific findings sometimes collided). However, the latter idea, popular among conspiracy theorists, seems highly unlikely: it is (and was even at the time) clear, even to a child, that the text in question could be easily read "backwards" (either directly or through its reflection, such as in a mirror). The true purpose of this practice thus remains unknown.
In a Study of the "Last Supper" Leonardo is "Bartolomeo".
Matteo Zaccolini apparently wrote in mirror script his original four volume treatise on optics, color, and perspective in the early 1600s; he was apparently dependent on Leonardo's text. --Rob ten Berge (talk) 06:46, 17 November 2007 (UTC)
Scuba Gear
Scuba diving is the act of swimming underwater while using self-contained breathing apparatus. By carrying a source of compressed air, the scuba diver is able to stay underwater longer than with the simple breath-holding techniques used in Snorkeling and Free-diving, and is not hindered by air-lines to a remote air source. The scuba diver typically swims underwater by using fins attached to the feet. However, some divers also move around with the assistance of a DPV (Diver Propulsion Vehicle), commonly referred to as a "scooter", or by using surface-tethered devices called sleds pulled by a boat.
For the history of diving, see Timeline of underwater technology.
The term SCUBA arose during World War II and originally referred to USA combat frogmen's oxygen rebreathers, developed by Dr. Christian Lambertsen for underwater warfare. Today, scuba typically usually refers to the in-line open-circuit equipment, developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water. However, rebreathers (both semi-closed circuit and closed circuit) are also self-contained systems (as opposed to surface-supplied systems) and are therefore classified as scuba.
Although the word 'SCUBA' is an acronym for "Self Contained Underwater Breathing Apparatus", it has also become acceptable to refer to scuba as 'scuba equipment' or 'scuba apparatus'an example of the linguistic RAS syndrome.
Water normally contains dissolved oxygen from which fish and other aquatic animals extract all their required oxygen as the water flows past their gills. Humans lack gills and do not otherwise have the capacity to breathe underwater unaided by external devices.
Early diving experimenters quickly discovered it is not enough simply to supply air in order to breathe comfortably underwater. As one descends, in addition to the normal atmospheric pressure, water exerts increasing pressure on the chest and lungs approximately 1 bar or 14.7 psi for every 33 feet or 10 meters of depth so the pressure of the inhaled breath must exactly counter the surrounding or ambient pressure in order to inflate the lungs.
By always providing the breathing gas at ambient pressure, modern demand valve regulators ensure the diver can inhale and exhale naturally and virtually effortlessly, regardless of depth.
Because the diver's nose and eyes are covered by a diving mask; the diver cannot breathe in through the nose, except when wearing a full face diving mask. However, inhaling from a regulator's mouthpiece becomes second nature very quickly.
The most commonly used scuba set today is the "single-hose" open circuit 2-stage diving regulator, coupled to a single pressurized gas cylinder, with the first stage on the cylinder and the second stage at the mouthpiece. This arrangement differs from Emile Gagnan's and Jacques Cousteau's original 1942 "twin-hose" design, known as the Aqua-lung, in which the cylinder's pressure was reduced to ambient pressure in one or two or three stages which were all on the cylinder. The "single-hose" system has significant advantages over the original system.
In the "single-hose" two-stage design, the first stage regulator reduces the cylinder pressure of about 200 bar (3000 psi) to an intermediate level of about 10 bar (145 psi) The second stage demand valve regulator, connected via a low pressure hose to the first stage, delivers the breathing gas at the correct ambient pressure to the diver's mouth and lungs. The diver's exhaled gases are exhausted directly to the environment as waste. The first stage typically has at least one outlet delivering breathing gas at unreduced tank pressure. This is connected to the diver's pressure gauge or computer, in order to show how much breathing gas remains.
Less common, but becoming increasingly available, are closed and semi-closed rebreathers. Open-circuit sets vent off all exhaled gases, but rebreathers reprocess each exhaled breath for re-use by removing the carbon dioxide buildup and replacing the oxygen used by the diver. Rebreathers release few or no gas bubbles into the water, and use much less oxygen per hour because exhaled oxygen is recovered; this has advantages for research, military, photography, and other applications. Modern rebreathers are more complex and more expensive than sport open-circuit scuba, and need special training and maintenance to safely use.
The Revolving Bridge
The Revolving Bridge is an invention by Leonardo da Vinci where his military and hydraulic occupation met: the bridge that could be swept away from the river on one of its pylons not only prevented advancing enemies from crossing but also allowed large ships to travel the water without being hindered by the bridge.
This is a model of one of the many "very light yet rugged" bridges described by Leonardo in his letter to Ludovico il Moro. These bridges were designed for construction with material that was readily available and easy to transport. The bridge with a parabolic profile has only one span and is secured to the two banks by means of a large vertical pin. It is moved by means of ropes and hoists, aided by wheels and metal rollers in performing its sliding motion. Moreover, the bridge is equipped with a counterweight tank for balancing and manoeuvring purposes, while suspended in the air before being laid down on the opposite bank.
In the drawing, dateable to Leonardo's early days in Milan, reference is made to those "ponti leggerissimi e forti atti a portare facilissimamente, e con quelli seguire e alcune volte fuggire li nemici, e altri securi e inoffensibili da foco di battaglie, facili e comodi da levare e ponere" (very light yet rugged bridges suitable for being moved, and for pursuing and sometimes escaping from the enemy, and others still, which are safe and cannot be burnt by the fire of battles and are easily removed and laid down).
Sources
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The Winged Glider
A "glider" is an unpowered aircraft. The most common types of glider are today used for sporting purposes. The design of these types enables them to climb using rising air and then to glide for long distances before finding the next source of lift. This has created the sport of gliding, or soaring. The term "sailplane" is sometimes used for these types, implying a glider with a high soaring performance. In addition to high-performance sailplanes, the term 'glider' also encompasses hang gliders and paragliders. Like sailplanes these can use upwardly moving air to soar but differ in not having a fuselage, control surfaces or a control column.
Although many gliders do not have engines, there are some that use engines occasionally (see Motor glider). The manufacturers of high-performance gliders now often list an optional engine and a retractable propeller that can be used to sustain flight if required; these are known as 'self-sustaining' gliders. Some can even launch themselves and are known as 'self-launching' gliders. There are also 'touring motor gliders', which can switch off their engines in flight though without retracting their propellers. The term "pure glider" (or equivalently, but less commonly "pure sailplane") may be used to distinguish a totally unpowered glider from a motorized glider, without implying any differential in gliding or soaring performance.
In China, kites rather than gliders were used for military reconnaissance. However the Extensive Records of the Taiping Era (978) suggests that a true glider was designed in the 5th century BC by Lu Ban, a contemporary of Confucius. There is also a report from the History of Northern Dynasties (659) and Zizhi Tongjian (1084) that Yuan Huangtou in Ye made a successful glide, taking off from a tower in 559.
Abbas Ibn Firnas invented the first weight shift aircraft ( hang glider) and is also claimed as the inventor of the first manned glider in 875 by fixing feathers to a wooden frame fitted to his arms or back. Written accounts at the time suggest that he made a ten minute flight. Abbas was seriously injured in the resulting crash.
The first heavier-than-air (i.e. non-balloon) aircraft to be flown in Europe was Sir George Cayley's series of gliders which achieved brief wing-borne hops from around 1804. Santos Dumont, Otto Lilienthal, Percy Pilcher, John J. Montgomery, and the Wright Brothers are other pioneers who built gliders to develop aviation. After the First World War gliders were built for sporting purposes in Germany (See link to Rh?n-Rossitten Gesellschaft) and in the United States (Schweizer brothers). The sporting use of gliders rapidly evolved in the 1930s and is now the main application. As their performance improved gliders began to be used to fly cross-country and now regularly fly hundreds or even thousands of kilometers in a day, if the weather is suitable.
Military gliders were then developed by a number of countries, particularly during World War II, for landing troops. A glider was even built secretly by POWs as a potential escape method at Oflag IV-C near the end of the war in 1944. The space shuttle orbiters do not use their engines after re-entry at the end of each spaceflight, and so land as gliders.
The two most common methods of launching gliders are by aerotow and by winch. When aerotowed, the glider is towed behind a powered aircraft using a rope about 60 meters (about 200 ft) long. The glider's pilot releases the rope after reaching the desired altitude, but the rope can also be released by the towplane in an emergency. Winch launching uses a powerful stationary engine located on the ground at the far end of the launch area. The glider is attached to one end of 800-1200 metres (about 2,500-4,000 ft) of wire cable and the winch then rapidly winds it in. More rarely, powerful automobiles are used to pull gliders into the air, by pulling them directly or through the use of a pulley in a similar manner to the winch launch. Elastic ropes can also be used to launch gliders off slopes if there is sufficient wind blowing up the hill. The glider will then gain height using ridge lift.
The most commonly used source of lift is created by the sun's energy heating the ground which in turn heats the air above it. This warm air rises in columns known as thermals. Soaring pilots quickly become aware of visual indications of thermals such as: cumulus clouds, cloud streets, dust devils and haze domes. Also, nearly every glider contains an instrument known as a variometer (a very sensitive vertical speed indicator) which shows visually (and often audibly) the presence of lift and sink. Having located a thermal, a glider pilot will circle within the area of rising air to gain height. In the case of a cloud street thermals can line up with the wind creating rows of thermals and sinking air. A pilot can use a cloud street to fly long straightline distances by remaining in the row of rising air.
Another form of lift occurs when the wind meets a mountain, cliff or hill. The air is deflected up the windward face of the mountain forming lift. Gliders can climb in this rising air by flying along the feature. This is referred to as "ridge running" and has been used to set record distance flights along the Appalachians in the USA and the Andes Mountains in South America. Another name for flying with ridge lift is slope soaring.
Early gliders had no cockpit and the pilot sat on a small seat located just ahead of the wing. These were known as "primary gliders" and they were usually launched from the tops of hills, though they are also capable of short hops across the ground while being towed behind a vehicle. To enable gliders to soar more effectively than primary gliders, the designs minimized drag. Gliders now have very smooth, narrow fuselages and very long, narrow wings with a high aspect ratio.
The early gliders were made mainly of wood with metal fastenings, stays and control cables. Later fuselages made of fabric-covered steel tube were married to wood and fabric wings for lightness and strength. New materials such as carbon-fiber, glass-fiber and Kevlar have since been used with computer-aided design to increase performance. The first glider to use glass-fiber extensively was the Akaflieg Stuttgart FS-24 Ph?nix which first flew in 1957. This material is still used because of its high strength to weight ratio and its ability to give a smooth exterior finish to reduce drag. Drag has also been minimized by more aerodynamic shapes and retractable undercarriages. Flaps are fitted on some gliders so that the optimal lift of the wing is available at all speeds.
With each generation of materials and with the improvements in aerodynamics, the performance of gliders has increased. One measure of performance is the glide ratio. A ratio of 30:1 means that in smooth air a glider can travel forward 30 meters while only losing 1 meter of altitude. Comparing some typical gliders that might be found in the fleet of a gliding club - the Grunau Baby from the 1930s had a glide ratio of just 17:1, the glass-fiber Libelle of the 1960s increased that to 39:1, and nowadays flapped 18 meter gliders such as the ASG29 have a glide ratio of over 50:1. The largest open-class glider, the eta, has a span of 30.9 meters and has a glide ratio over 70:1. Compare this to the infamous Gimli Glider, a Boeing 767 which ran out of fuel mid-flight and was found to have a glide ratio of only 12:1, or to the Space Shuttle with a glide ratio of 3:1.
Due to the critical role that aerodynamic efficiency plays in the performance of a glider, gliders often have state of the art aerodynamic features seldom found in other aircraft. The wings of a modern racing glider have a specially designed low-drag laminar flow airfoil. After the wings' surfaces have been shaped by a mold to great accuracy, they are then highly polished. Vertical winglets at the ends of the wings are computer-designed to decrease drag and improve handling performance. Special aerodynamic seals are used at the ailerons, rudder and elevator to prevent the flow of air through control surface gaps. Turbulator devices in the form of a zig-zag tape or multiple blow holes positioned in a span-wise line along the wing are used to trip laminar flow air into turbulent flow at a desired location on the wing. This flow control prevents the formation of laminar flow bubbles and ensures the absolute minimum drag. Bug-wipers may be installed to wipe the wings while in flight and remove insects that are disturbing the smooth flow of air over the wing.
Modern competition gliders are also designed to carry jettisonable water ballast (in the wings and sometimes in the vertical stabiliser). The extra weight provided by the water ballast is advantageous if the lift is likely to be strong, and may also be used to adjust the glider's center of mass. Although heavier gliders have a slight disadvantage when climbing in rising air, they achieve a higher speed at any given glide angle. This is an advantage in strong conditions when the gliders spend only little time climbing in thermals. The pilot can jettison the water ballast before it becomes a disadvantage in weaker thermal conditions. To avoid undue stress on the airframe, gliders must jettison any water ballast before landing.
Pilots can land accurately by controlling their rate of descent using spoilers, also known as air brakes. These are metal devices which extend from either the upper-wing surface or from both upper and lower surfaces, thereby destroying some lift and creating additional drag. A wheel-brake also enables a glider to be stopped after touchdown, which is particularly important in a short field.
The Triple-Barreled Cannon
The anime series Mobile Suit Gundam, set in the fictional Universal Century is centered around the conflict known as the One Year War (or OYW for short), between two military factions: the earthbound Earth Federation Forces(EFF for short) and the spacebound Principality of Zeon(Zeon for short), each utilizing different machines of war, although the series is famous for its mobile suits, there are other military units like space battleships, carriers, tanks and fighters as well. This is a major break through in the robot anime at the time where other robot anime preceding this are of the Super Robot genre which introduces robots owned by individual research centres fighting against evil, yet Mobile Suit Gundam introduces robots as weapons of the military units like main battle tanks and fighters. It is also interesting watching the difference between the designs of the weapons, which also tend to represent the context in which the weapons were created, specially in the case of the Zeon, which deploys many designs that were tested in space colonies, which utlimately prove uncapable of providing the adequate conditions to test aircraft and other vehicles, and therefore tend to have unusual designs that seem faulty at first glance. On the other hand, the weapons of the EFF, specially the ones for the ground, aerial and naval combat, seem outdated compared with ones deployed by Zeon. This is mainly result of the EFF focusing on fortifying their space forces, which other than MS, are more up to date with Zeon own space forces. Basically, the different types of vehicles can be classified according to their role, whether this is as a spaceship, a landship, aircraft, boat, submarine, tank, etc. Furthermore, not all of them are battleships. Many vehicles are designed for specific functions such as supply transport units, recon units, and in some cases, even as units that work together with MS, providing additional firepower or even the atmospheric flight capacity.
As previously mentioned, the series focus on the use of both Mobile weapons, specially Mobile Suits(or MS for short), and as military weapons, MS also need maintenance, and while this can be provided without a ship, it proves useful to provide it while allowing transportation for them. Therefore many of the ships and vehicles will actually provide the MS capacity stat, which reflects, how many MS can a ship carry, specially in the case of the Zeon, which creates many ships with this capability in mind. Here is a list of military units that appear in the show.
The Fat Uncle transport aircraft was the primary non-combat transport aircraft for the Principality of Zeon during the One Year War. The Fat Uncle's ungainly belied it's true effectiveness, as it was a highly efficient aircraft, able to carry nearly twice its weight in cargo, including Zaku-type mobile suits standing in the massive cargo bay. This was in part due to the powerful thermonuclear jet engines used for thrust, and the large VTOL rotors used for lift. Despite the similarities between the thermonuclear jet engines of the Fat Uncle and Gaw class assault carrier, it's unknown if they use the same type of engines, but it's certainly a possibility. The Fat Uncle could roughly carry three mobile suits, but the exact capacity it can carry is difficult to estimate, as it was not originally designed to carry mobile suits, but rather a more general range of cargo. A Fat Uncle is seen next to Ramba Ral's Gallop, after providing them with a Zaku II. Another is seen transporting a Zock and Z'Gok MS to Char Aznable's Mad Angler submarine.
The Gaw Atmospheric Attack Carrier, known very simple as the Gaw, is a flying fortress that was sent in to attack and obliterate its target. The Gaw also sported three double-barreled mega particle cannons for attacking bases and other large-scale aircraft. It also had several machineguns for point defense.
The Gaw's eight Dopps and three MS units made them very effective in their ship-type as carriers. The Gaw could also hold six vehicles on its rear hangar, such as the Cui Personal Carrier or Magella Attack Tank. In some cases these vehicles could be replaced by three additional MS units which would be parachuted in a similar way Medeas eject their MS. It also has a large number of gravity bombs which made them extremely effective as carpet bombers.
Several Gaws were used in the unsuccessful Zeon offensive in their attempt to take the Earth Federation's General Headquarters in Jaburo, in which they dropped off their payloads of mobile suits to take the attack to the ground and to try to force their way inside.
The Aerial Screw
"Trovo, se questo strumento a vite sar? ben fatto, cio? fatto di tela lina, stopata i suoi pori con amido, e svoltata con prestezza, che detta vite si fa la femmina nellaria e monter? in alto". "I believe that if this screw device is well manufactured, that is, if it is made of linen cloth, the pores of which have been closed with starch, and if the device is promptly reversed, the screw will engage its gear when in the air and it will rise up on high"
This is one of Leonardo's best known drawings. Some experts have identified it as the ancestor of the helicopter. The only drawing accompanying Leonardo's note is the sketch of an aerial screw with a diameter of 5 metres, made of reed, linen cloth and wire, operated presumably by four men who might have stood on the central platform and exerted pressure on the bars in front of them with their hands, so as to make the shaft turn. A machine thus designed would probably never have risen off the ground or been set moving; the idea remains, however, that if an adequate driving force were applied, the machine might have spun in the air and risen off the ground.
Leonardo's Idea
The drawing of the aerial screw was made during Leonardo's first period in Milan and may be dated between 1483 and 1486. It belongs to the first series of machines designed for mechanical flight. The aerial screw differs from the other machines in that it was planned for the study of the propeller's tractive efficiency and not as a real flying machine. In the note accompanying the drawing, Leonardo, in fact, suggests that, by way of example, what he claims can be experimented by taking a thin, wide rod and rotating it fast in the air. This will prove that the arm of the person rotating the rod will be pulled upward towards the rod itself. In the same note, Leonardo suggests making a paper model of a screw and launching it by means of a coil spring wrapped around the base of the screw. The specific mentioning of the screw strengthens the assumption that this model was actually a representation of the windmill game, a toy which was already popular in Leonardo's age. Due to its small size, the toy could be operated by a spring or, better still, by a small rope, the fast unwinding of which turned the screw and made it move upward. This might be the source of the intuition that the same mechanism, larger in size and operated by an adequate driving force, could have risen off the ground.
The Ideal City
Ever since Ancient Egypt, civilizations have attempted to plan cities in order to make them work better. Planners seek to organize a city so that it benefits all its inhabitants. They do things such as build housing, construct infrastructure like roads and plumbing, provide public services like electricity and garbage collection, coordinate commerce, provide recreational facilities such as parks, stadiums and museums, and facilitate transport. These days, planning is not a simple job suited for one department or group. More and more, the cooperation of a number of government departments, local organizations and private citizens is needed to make a city, even a neighborhood, function healthily. Nevertheless, a coherent vision of what is necessary, what is good and what works is needed if cities are going to survive in the future. The students job is to construct that vision. In groups or as a class, students should form an Ideal City committee. Over the course of several weeks student committees will be designing their ideal city. Each weeks activity helps students build up their knowledge of cities and the things necessary to have a healthy, successful city. At the end, they will be ready to design their ideal city. The ideal city can be drawn, built (3-D model) or written upthe teacher will help decide which approach to take. Before getting started, or as you go along, you may want to consult the Doing Good folder, which lists some of the cities that have made great improvements in one or more respects. Good luck and make sure you enjoy your citythats essential for its health and yours. Note: The teacher should keep in mind that, while the first two activities are simple and essential, the later ones become more difficult. Teachers of lower grades might think about (i) collapsing activities 3 and 4 into a single activity; (ii) simplifying activity 6 by asking students to design the city without considering the final suggestions and discussing those concerns (advantages and disadvantages, correlation with goals) at a later date.
This Ideal City activity can be done as an extension of question 6 of Unit 2. Refer to definitions of site and situation in question 6. Pick a site for your ideal city and describe its situation. You can either create an imaginary situation or use an atlas and/or a map to pick a siteit could be your own city, a place nearby or somewhere quite far. Explain the advantages of the site and situation you chose. You can start drawing, constructing or writing about the site at this stage.
This Ideal City activity can be done as an extension of questions 2, 3 or 6 of Unit 3. Refer to definitions of infrastructure and services in the text. Think about your home. What would it be like without light? Do you watch television? Do you shower everyday or wash the vegetables? What if there were no water? How do you get from home to school or to your friends' homes? What if there were no roads?
Your home is a structure built from wood or bricks. But it has strong beams and a srong foundation to hold it up; it could have plumbing to get water to you and cables to bring you electrcity. These are part of its infrastructure. The city is a larger version of the same thingit has cables and plumbing running all through it to take things such as water and electricity to the inhabitants.
In this way, your daily life is tied to the life of the city, your home is part of a city's environment. Without a city infrastructure your life would be different. Of course, not all cities have all the necessary infrastructure and those that do, don't have them in all neighborhoods. This is something you should keep in mind. (As explained in the text: the cables drawn in the city are part of the infrastructure; providing electricity is part of the services. With transport it is the same: roads are part of the infrastructure; buses are part of the services.)
Think of other examples of infrastructure without which your city would not function as smoothly. Now think of examples of infrastructure that your city does not have or needs to improve onthe first three columns of your Planning Table could give you some ideas. Draw two more columns in your Planning Table. Place all your examples in the fourth column (call it Infrastructure).
Compare this column to the previous three. Are there any items in this last column that were not mentioned in the other ones? If so, discuss in which column the item would fit and place it there as well.
This activity can be done as an extension of question 4 in Unit 5.
Now your Planning Table is complete. This is your main guide. Everything that is checked off in column 5 should be considered a BASIC NEED.
From Activity 2, you also have a site and situation in place.
In short, you are ready to begin planning your city. But where do you begin? You need some goals to reach for and you must be aware of some pitfalls to avoid. Luckily, cities already exist and we can learn much from them. And luckily, you already have two columns of positive and negative things about cities.
Now use these two columns, and all that you have learned through this course of study, to draw up a set of goals -- stating what you want your ideal city to achieve. For example, your goals could read something like this: This Ideal City will provide safe drinking water to ALL its inhabitants....This Ideal City will reduce air pollution... These are only suggestions. You can come up with your own goals and your own solutions. This set of goals will give you direction, it will act as your compass.
You now have three tools you can use to design your city. You have "Goals", a "Planning Table", and a "Site". Your problem now is to bring all of it together in a workable way, to make an Ideal City that will make sense. From here on, you are on your own.
Here are some suggestions as to how you can go about this. Think about your site and the layout of your city. That is, think about where you want to put what. Do you want your city to be sprawled over a vast territory or do you want it to be concentrated in a more limited area? What are the advantages and disadvantages of each? How does it affect your goals? Think this way about all the other aspects of the layout. Where would you put things such as schools and markets? How about parks? Where would the main roads and highways run?
Think carefully about your goals, as they show you where you want to end up. Then think about how you can achieve each goal. Look at the services and infrastructure columns on your planning table. Will any of these help you achieve your goals? For example, one of your goals may be to keep air pollution low. How could you achieve this goal? In the services column, there could be an item called Public Transport. How would this help you achieve your goal?
So there is an infrastructure. What now? How, people might ask, do we get from one place to the next? There may be roads, but what about buses? They need garbage collection and a place to dispose of it. They need to have clean water running in the pipes. They need places to buy bread and clothing. They need such services in order to live healthily and keep the city healthy. As the city grows, its organization becomes more complex (and, of course, more expensive). The needs and demands of citizens change. Many arrive from remote areas or other countries and are not sure what to expect. What they find is not always what they had dreamt. To be healthy, a city must also be just. To be healthy, according to the criteria suggested by the World Health Organization (WHO), a city must meet the BASIC needs of ALL its inhabitants. In the final column of your Planning Table list all the services needed by citizens in order to lead a good life in the city (call this column services). There are some mentioned in Units 3 and 4. Can you come up with more? Think of your own life and all the different things you do during the week and on weekends.
Now that you have all the services listed, go through them and discuss which ones are essentialthe BASIC NEEDS without which it would be impossible to live a healthy life. Place a check beside each one of those services you think is essential.
As with the last activity, compare this column to the first three, positive, negative and improvements. Are there any items in this last column that you did not mention in the first three? If so, discuss in which column the item would fit and place it there as well.
The Self-Propelled Car
A self-propelled car is placed on a handcart in such a manner that it can freely ride on and ride off of the handcart. The handcart is provided with at least one roller which engages with the driving wheels of the self-propelled car to interrupt the running thereof.
1. A traveling apparatus comprising a self-propelling car having a drive means and having front and rear drive wheels, a hand carriage cart having a mount means for allowing said self-propelling car to be mounted thereon and dismounted therefrom,
wherein said self-propelling car has front wheels driven by said drive means in a first direction of rotation, said hand carriage cart having a freely rotatable roller; said self-propelling car is stopped at a predetermined position on said mount means by abutment of said front wheels against said roller,
wherein said front wheels freely rotate against said roller and wherein the drive force of said front wheels is rendered null and void by said wheels freely rotating against said roller,
wherein said self propelling car front drive wheels are driven in the opposite direction as said rear drive wheels,
wherein only one of said front and said rear wheels are driven at a time, and spaced rollers on said hand carriage cart having one-way clutches to engage said front and rear wheels, and
wherein said self-propelling car is moved on and off of said hand carriage cart when said front and rear wheels change to a second direction of rotation and engage said spaced rollers which are prevented from rolling by said one-way clutches.
2. A traveling apparatus in accordance with claim 1 wherein said front and rear wheels on said self-propelling car have one-way clutches which alternately permit rotation in opposite directions.
1. Field of the Invention
The present invention relates to a handcart for use in conveyance which enables the direction of progress of a self-propelled car to be readily changed.
2. Description of the Related Art
Electric motor driven self-propelled cars have been used in the operations in a greenhouse (a hothouse), which are required to grow, for example, vegetables. Such self-propelled cars are capable of moving back and forth between ridges in the greenhouse, and are used to sprinkle water or spray chemicals over the plants.
It is general that the above-described type self-propelled car can automatically move back and forth along a longitudinal region between adjacent ridges but that it must be manually moved in the lateral direction in a head region to a position where it faces another adjacent longitudinal region.
Japanese Utility Model Unexamined Publication No. 58-189783 discloses a technique for automatically moving this self-propelled car in the lateral direction in the head region to a position where it faces another adjacent longitudinal region. In this technique, an electric motor driven self-propelled cart capable of moving in the lateral direction with the self-propelled car placed thereon is provided.
However, in the conventional technique of the above-described type, both the self-propelled car and the cart are respectively provided with a driving device. One of the driving devices is not used at all while the self-propelled car or the cart is being moved in its associated direction. Furthermore, switch-over operation between the two driving devices requires a complicated structure.
Furthermore, a special consideration has to be made to safely absorb the running force by inertia without applying overloads on the individual components when the self-propelled car is automatically stopped at a predetermined position on the cart. Hence, the overall size and the weight of the apparatus are increased, and the production cost is increased. Installation of the apparatus is a troublesome work, and a failure readily occurs.
SUMMARY OF THE INVENTION
In view of the aforementioned problems of the prior techniques, an object of the present invention is to provide a handcart for use in conveyance which is provided with a roller which engages with driving wheels of a self-propelled car when the self-propelled car is placed on the handcart to interrupt the running of the self-propelled car.
In consequence, when the self-propelled car rides on the handcart, running of the self-propelled car is automatically interrupted, and the handcart with the self-propelled car placed thereon can be freely wheeled to any position.
More specifically, in the handcart for use in conveyance according to the present invention, driving force of the self-propelled car is made null and void by utilizing the roller provided on the handcart, and the self-propelled car can therefore be automatically and safely stopped without applying overloads to the individual components. Further, the overall mechanism of the system can be simplified, and the size and the weight thereof can be reduced. The production cost is low. The handcart according to the present invention is reliable and suitable for use in labor-saving operations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevational view of one embodiment of a handcart according to the present invention;
FIG. 2 is a plan view of the handcart of FIG. 1; and
FIG. 3 is a side view of the handcart of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the accompanying drawings.
A self-propelled car 1 is capable of automatically moving back and forth along a longitudinal region 23 between adjacent ridges 21 and 22 in a greenhouse. A handcart 7 is capable of moving in the lateral direction along a head region 27 located at one end of each of the ridges 21,22 in a state where the self-propelled car 1 is placed thereon.
Although the self-propelled car 1 is not described in detail because it is not the gist of the present invention, it is provided with an automatic-winding hose reel and a spraying nozzle. The self-propelled car 1 is equipped with an electric motor which serves as a self-propelling means. Power is supplied to the motor from a battery mounted on the car 1. The self-propelled car 1 also has front and rear rubber tire type wheels 2 and 3 (the left side of the handcart as viewed in FIG. 1 is referred to as the front for convenience) on two axes, by means of which it can travel forward and backward.
One-way clutchs (not shown) for front wheels and rear wheels which rotate in opposite directions each other when the self-propelled car 1 moves in the forward and rearward directions may be provided between each of the rubber front and rear wheels 2 and 3 and the electric motor so as to allow only the front wheels as viewed in the advancing direction of the self-propelled car 1 to operate as the driving wheels. In this way, running performance of the self-propelled car 1 can be improved.
Switch rods 4 and 5 for switching-over the direction of rotation of the electric motor protrude from the front and rear ends of the self-propelled car 1. When the switch rod 5 provided at the rear end abuts against a post (not shown) provided at the other end of the longitudinal region 23 which is remote from the head region 27, the direction of rotation of the electric motor is switched-over, and the forward and rearward movements of the self-propelled car 1 are thereby automatically switched-over.
By pushing in the switch rod 4 provided at the front end when the handcart 7 with the self-propelled car 1 therein is conveyed in the lateral direction to the central position of the subsequent longitudinal region 23, the self-propelled car 1 starts moving forward again. Then, the self-propelled car 1 is running forward again at the central position of the subsequent longitudinal region 23.
The handcart 7 has a cross-shaped frame member 28 which extends in the longitudinal direction which is the direction in which the longitudinal region 23 extends and in the lateral direction which is the direction in which the head region 27 extends. Two axes 18 and 15 are mounted on the lateral front and rear ends (the downward end as viewed in FIG. 2 is referred to as the front end for convenience) of the frame member 28 by means of mounting members 26, and rubber tire type front and rear wheels 19 and 17 are rotatably mounted at the two ends of the individual axis 18 and 15. In consequence, the handcart 7 can be wheeled in the forward and rearward directions along the head region 27 by pushing handles 6 provided at the lateral front and rear ends of the frame member 28.
Floor plates 24 extend from the central portion of the frame member 28 to the longitudinal rear end thereof through a length which corresponds to the tread of the wheels 2 and 3 of the self-propelled car 1. A slope plate 20 is provided at the longitudinal rear end of the floor plates 24 so as to facilitate the riding of the self-propelled car 1 onto the handcart 7. The slope plate 20 is raised by means of an adequate coupling means (which is not shown) once the self-propelled car 1 rides on the handcart 7.
At the longitudinal front end of the frame member 28 are rotatably provided rollers 8 and 9, which press against the lower front and rear sides of the rubber tire type front wheels 2 when the self-propelled car 1 is placed at its position on the handcart 7. The rollers 8 and 9 make the driving force of the rubber tire type front wheels 2 in the forward direction null and void, and thereby interrupt running of the self-propelled car 1.
The front roller 8 is larger in diameter than the rear one 9 so as to ensure that running of the self-propelled car 1 is stopped reliably.
If the front roller 8 is the same as the rear roller 9, it may be mounted at the upper position so as to secure the same effect.
The slope plate 20, the floor plates 24, the front roller 8 may be made of an expanded metal (a reticulated steel plate) so as to facilitate removal of mud.
The self-propelled car 1, which is advanced along the longitudinal region 23, rides on the handcart 7, where the rubber tire type front wheels 2 of the self-propelled car 1 press against the rollers 8 and 9 of the handcart, and the progress thereof is thereby hindered. In consequence, even when the rubber tire type front wheels 2 continue rotating, the driving force of the front wheels 2 is absorbed by the rollers 8 and 9 and is made null and void, thereby automatically interrupting the running of the self-propelled car 1. Afterwards, whether the power is turned off or not, the handcart 7 with the self-propelled car 1 thereon can be wheeled by an operator who pushes the handle 6.
The above description explains the case of a self-propelled car 1 in which only the front wheels 2 are driving wheels. In order to allow the present invention to be applied to a rear wheel or four wheel drive self-propelled car, the handcart 7 may be provided with rollers 12 and 13 which press against the lower front and rear sides of the rear wheels 3. Foot plates may be detachably mounted on the rollers 12 and 13.
Furthermore, the rollers 9 and 13 with which the lower rear sides of the front and rear wheels 2 and respectively make contact may be respectively provided with one-way clutches 14 and 16 for permitting rolling of the rollers 9 and 13 only to the right as viewed in FIG. 1.
More specifically, in a case of the front wheel drive self-propelled car 1, the rollers 12 and 13 for the rear wheels 3 are covered by the foot plates 25 to make them null and void. When the self-propelled car 1 rides on the handcart 7, the front wheels 2 of the self-propelled car 1, which are the driving wheels, ride on the roller 9 of the handcart 7. Thereafter, the self-propelled car 1 advances by inertia, and the front wheels 2 abut against the large diameter roller 8, thereby automatically stopping the self-propelled car 1 even though the front wheels 2 of the self-propelled car 1 continue rotating.
In that state, the operator pushes the handcart 7 to the central position of a subsequent longitudinal region 23 and presses the switch rod 4 provided at the front end of the self- propelled car 1. This makes the rear wheels 3 operate as the driving wheels, and the self-propelled car 1 therefore starts running past the foot plates 25 and out of the handcart 7, and then along the longitudinal region 23.
Once the self-propelled car 1 reaches the other end of the longitudinal region 23 and the rear switch rod 5 strikes the post and is therefore pushed in, the front wheels 2 start operating as the driving wheels, and the self-propelled car 1 moves back along the longitudinal region 23 and then rides again on the handcart 7 located at the head region 27, where the driving force of the self-propelled car 1 is absorbed by the rollers 8 and 9 to interrupt the running. Thereafter, the above-described sequence of operations are repeated. Once the operation is completed, power is turned off, and the operator conveys the handcart 7 with the self-propelled car 1 thereon to an appropriate position by pushing the handle 6.
In the case of a rear wheel drive self-propelled car 1, the foot plates 25 of the handcart 7 are removed so as to allow the rear rollers 12 and 13 to operate. When the self-propelled car 1 is located on the handcart 7, the driving force of the rear wheels 3 which are the driving wheels of the self-propelled car 1 is made null and void by the rear rollers 12 and 13, and the running of the self-propelled car 1 is thereby interrupted.
When the self-propelled car 1 is to be lowered from the handcart 7, the switch rod 4 is pushed in to allow the front wheels 2 to rotate rightward as viewed in FIG. 1 and thereby operate as the driving wheels. At that time, the one-way clutch 14 provided on the roller 9 operates to prevent rotation of the roller 9 leftward as viewed in FIG. 1. As a result, the driving force is effectively imparted to the self-propelled car 1, and the self-propelled car 1 starts running and goes down from the handcart 7.
In the case of a four wheel drive self-propelled car 1 in which both the fount and rear wheels operate as the driving wheels, the foot plates 25 are removed, like the case of the rear wheel drive self-propelled car. When the self-propelled car 1 rides on the handcart 7, it rides on the rollers 8, 9 and 12, 13, and the driving force is made null and void to interrupt the running of the self-propelled car 1.
Next, when the self-propelled car 1 is to be lowered from the handcart 7, the switch rod 4 provided at the front end is pushed in to allow the front and rear wheels 2 and 3 to rotate rightward as viewed in FIG. 1 and thereby operate as the driving wheels. At that time, the one-way clutches 14 and 16 operate to prevent rotation of the rollers 9 and 13 leftward as viewed in FIG. 1. As a result, the driving force of the front and rear wheels 2 and 3 is effectively imparted to the self-propelled car 1, and the self-propelled car 1 starts running even though it is so heavy.
Geologic Time
The geological time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of Earth. The table of geologic periods presented here agrees with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geological Survey.
Evidence from radiometric dating indicates that the Earth is about 4.570 billion years old. The geological or deep time of Earth's past has been organized into various units according to events which took place in each period. Different spans of time on the time scale are usually delimited by major geological or paleontological events, such as mass extinctions. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the extinction event, known as the CretaceousTertiary extinction event, that marked the demise of the dinosaurs and of many marine species. Older periods which predate the reliable fossil record are defined by absolute age.
The largest defined unit of time is the supereon comprised of Eons. Eons are divided into Eras, which are in turn divided into Periods, Epochs and Stages. At the same time paleontologists define a system of faunal stages, of varying lengths, based on changes in the observed fossil assemblages. In many cases, such faunal stages have been adopted in building the geological nomenclature, though in general there are far more recognized faunal stages than defined geological time units.
Geologists tend to talk in terms of Upper/Late, Lower/Early and Middle parts of periods and other units , such as "Upper Jurassic", and "Middle Cambrian". Upper, Middle, and Lower are terms applied to the rocks themselves, as in "Upper Jurassic sandstone," while Late, Middle, and Early are applied to time, as in "Early Jurassic deposition" or "fossils of Early Jurassic age." The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic." Because geologic units occurring at the same time but from different parts of the world can often look different and contain different fossils, there are many examples where the same period was historically given different names in different locales. For example, in North America the Lower Cambrian is referred to as the Waucoban series that is then subdivided into zones based on trilobites. The same timespan is split into Tommotian, Atdabanian and Botomian stages in East Asia and Siberia. A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can be used around the world.
The principles underlying geologic (geological) time scales were laid down by Nicholas Steno in the late 17th century. Steno argued that rock layers (or strata) are laid down in succession, and that each represents a "slice" of time. He also formulated the principle of superposition, which states that any given stratum is probably older than those above it and younger than those below it. While Steno's principles were simple, applying them to real rocks proved complex. Over the course of the 18th century geologists realized that: Sequences of strata were often eroded, distorted, tilted, or even inverted after deposition; Strata laid down at the same time in different areas could have entirely different appearances; The strata of any given area represented only part of the Earth's long history.
The first serious attempts to formulate a geological time scale that could be applied anywhere on Earth took place in the late 18th century. The most influential of those early attempts (championed by Abraham Werner, among others) divided the rocks of the Earth's crust into four types: Primary, Secondary, Tertiary, and Quaternary. Each type of rock, according to the theory, formed during a specific period in Earth history. It was thus possible to speak of a "Tertiary Period" as well as of "Tertiary Rocks." Indeed, "Tertiary" (now Paleocene-Pliocene) and "Quaternary" (now Pleistocene-Holocene) remained in use as names of geological periods well into the 20th century.
In opposition to the then-popular Neptunist theories expounded by Werner (that all rocks had precipitated out of a single enormous flood), a major shift in thinking came with the reading by James Hutton of his Theory of the Earth; or, an Investigation of the Laws Observable in the Composition, Dissolution, and Restoration of Land Upon the Globe before the Royal Society of Edinburgh in March and April 1785, events which "as things appear from the perspective of the twentieth century, James Hutton in those reading became the founder of modern geology" What Hutton proposed was that the interior of the Earth was hot, and that this heat was the engine which drove the creation of new rock: land was eroded by air and water and deposited as layers in the sea; heat then consolidated the sediment into stone, and uplifted it into new lands. This theory was dubbed "Plutonist" in contrast to the flood-oriented theory.
The identification of strata by the fossils they contained, pioneered by William Smith, Georges Cuvier, Jean d'Omalius d'Halloy and Alexandre Brogniart in the early 19th century, enabled geologists to divide Earth history more precisely. It also enabled them to correlate strata across national (or even continental) boundaries. If two strata (however distant in space or different in composition) contained the same fossils, chances were good that they had been laid down at the same time. Detailed studies between 1820 and 1850 of the strata and fossils of Europe produced the sequence of geological periods still used today.
The process was dominated by British geologists, and the names of the periods reflect that dominance. The "Cambrian," (the Roman name for Wales) and the "Ordovician," and "Silurian", named after ancient Welsh tribes, were periods defined using stratigraphic sequences from Wales. The "Devonian" was named for the English county of Devon, and the name "Carboniferous" was simply an adaptation of "the Coal Measures," the old British geologists' term for the same set of strata. The "Permian" was named after Perm, Russia, because it was defined using strata in that region by a Scottish geologist Roderick Murchison. However, some periods were defined by geologists from other countries. The "Triassic" was named in 1834 by a German geologist Friedrich Von Alberti from the three distinct layers (Latin trias meaning triad) red beds, capped by chalk, followed by black shales that are found throughout Germany and Northwest Europe, called the 'Trias'. The "Jurassic" was named by a French geologist Alexandre Brogniart for the extensive marine limestone exposures of the Jura Mountains. The "Cretaceous" (from Latin creta meaning 'chalk') as a separate period was first defined by a Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris basin and named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates).
British geologists were also responsible for the grouping of periods into Eras and the subdivision of the Tertiary and Quaternary periods into epochs.
When William Smith and Sir Charles Lyell first recognized that rock strata represented successive time periods, time scales could be estimated only very imprecisely since various kinds of rates of change used in estimation were highly variable. While creationists had been proposing dates of around six or seven thousand years for the age of the Earth based on the Bible, early geologists were suggesting millions of years for geologic periods with some even suggesting a virtually infinite age for the Earth. Geologists and paleontologists constructed the geologic table based on the relative positions of different strata and fossils, and estimated the time scales based on studying rates of various kinds of weathering, erosion, sedimentation, and lithification. Until the discovery of radioactivity in 1896 and the development of its geological applications through radiometric dating during the first half of the 20th century (pioneered by such geologists as Arthur Holmes) which allowed for more precise absolute dating of rocks, the ages of various rock strata and the age of the Earth were the subject of considerable debate.
In 1977, the Global Commission on Stratigraphy (now the International Commission on Stratigraphy) started an effort to define global references (Global Boundary Stratotype Sections and Points) for geologic periods and faunal stages. The commission's most recent work is described in the 2004 geologic time scale of Gradstein et al.. A UML model for how the timescale is structured, relating it to the GSSP, is also available.
The Vitruvian Man
The Vitruvian Man is a world-renowned drawing with accompanying notes created by Leonardo da Vinci around the year 1492 as recorded in one of his journals. It depicts a nude male figure in two superimposed positions with his arms and legs apart and simultaneously inscribed in a circle and square. The drawing and text are sometimes called the Canon of Proportions or, less often, Proportions of Man. It is stored in the Gallerie dell'Accademia in Venice, Italy, but is only displayed on special occasions.
Leonardo based his drawing on some hints at correlations of ideal human proportions with geometry in Book III of the treatise De Architectura by the ancient Roman architect Vitruvius, thus its name. Other artists had attempted to realize the conception, with less success. Vitruvius described as the principal source of proportion among the orders of architecture the proportion of the human figure.
This image exemplifies the blend of art and science during the Renaissance and provides the perfect example of Leonardo's keen interest in proportion. In addition, this picture represents a cornerstone of Leonardo's attempts to relate man to nature. Encyclopaedia Britannica online states, "Leonardo envisaged the great picture chart of the human body he had produced through his anatomical drawings and Vitruvian Man as a cosmografia del minor mondo (cosmography of the microcosm). He believed the workings of the human body to be an analogy for the workings of the universe." It is also believed by some that Leonardo symbolized the material existence by the square and spiritual existence by the circle. Thus he attempted to depict the correlation between these two aspects of human existence. According to Leonardo's notes in the accompanying text, written in mirror writing, it was made as a study of the proportions of the (male) human body as described in Vitruvius, who wrote that in the human body: a palm is the width of four fingers a foot is the width of four palms (and is 12 inch) a cubit is the width of six palms a man's height is four cubits (and thus 24 palms) a pace is four cubits the length of a man's outspread arms is equal to his height the distance from the hairline to the bottom of the chin is one-tenth of a man's height the distance from the top of the head to the bottom of the chin is one-eighth of a man's height the maximum width of the shoulders is a quarter of a man's height the distance from the elbow to the tip of the hand is one-fifth of a man's height the distance from the elbow to the armpit is one-eighth of a man's height the length of the hand is one-tenth of a man's height the distance from the bottom of the chin to the nose is one-third of the length of the head the distance from the hairline to the eyebrows is one-third of the length of the face the length of the ear is one-third of the length of the face
Leonardo is clearly illustrating Vitruvius' De architectura 3.1.3 which reads: The navel is naturally placed in the centre of the human body, and, if in a man lying with his face upward, and his hands and feet extended, from his navel as the centre, a circle be described, it will touch his fingers and toes. It is not alone by a circle, that the human body is thus circumscribed, as may be seen by placing it within a square. For measuring from the feet to the crown of the head, and then across the arms fully extended, we find the latter measure equal to the former; so that lines at right angles to each other, enclosing the figure, will form a square.
The multiple viewpoint that set in with Romanticism has convinced us that there is no such thing as a universal set of proportions for the human body. The field of anthropometry was created in order to describe these individual variations. Vitruvius' statements may be interpreted as statements about average proportions. Vitruvius goes through some trouble to give a precise mathematical definition of what he means by saying that the navel is the center of the body, but other definitions lead to different results; for example, the center of mass of the human body depends on the position of the limbs, and in a standing posture is typically about 10 cm lower than the navel, near the top of the hip bones.
Note that Leonardo's drawing combines a careful reading of the ancient text, combined with his own observation of actual human bodies. In drawing the circle and square he correctly observes that the square cannot have the same center as the circle, the navel, but is somewhat lower in the anatomy. This adjustment is the innovative part of Leonardo's drawing and what distinguishes it from earlier illustrations. He also departs from Vitruvius by drawing the arms raised to a position in which the fingertips are level with the top of the head, rather than Vitruvius's much higher angle, in which the arms form lines passing through the navel.
The drawing itself is often used as an implied symbol of the essential symmetry of the human body, and by extension, to the universe as a whole.
It may be noticed by examining the drawing that the combination of arm and leg positions actually creates sixteen different poses. The pose with the arms straight out and the feet together is seen to be inscribed in the superimposed square. On the other hand, the "spread-eagle" pose is seen to be inscribed in the superimposed circle.