Test and validation centre, Wegberg-Wildenrath
The Test and validation centre, Wegberg-Wildenrath is a railway test centre owned by Siemens Mobility near Wildenrath in North Rhine-Westphalia, Germany. The centre is located on the site of the former RAF Wildenrath British military airfield. After the airfield closed in 1992, it was taken over by Siemens who opened the test and validation centre in June 1997. By 2007, the railway test tracks had taken over considerable areas of the airfield, with all but the western threshold and overrun of the runway obliterated; the north-east dispersal is taken over by sidings and loops. Of the southern dispersals, the central and eastern are bisected by the main railway oval test track. There are ovals of track for testing trains, various electrification systems; the test track is connected to the rest of the German railway network by the German portion of the Iron Rhine freight railway, branching off near Wegberg. As well as Siemens the test tracks are used by competitors such as Alstom and Bombardier Transportation.
There are standard gauge and metre gauge tracks. The facility is used for technical acceptance tests and approvals of locomotives, rolling stock and trams under operating conditions, personnel training, it has been equipped for trials with Galileo. Transportation Technology Center, Inc. Test- and Validationcenter Wegberg-Wildenrath, Siemens Mobility Railway tests and test infrastructure right in the heart of Europe, Siemens Mobility
A hermetic seal is any type of sealing that makes a given object airtight. The term applied to airtight glass containers, but as technology advanced it applied to a larger category of materials, including rubber and plastics. Hermetic seals are essential to the correct and safe functionality of many electronic and healthcare products. Used technically, it is stated in conditions of use; the word hermetic comes via the vocabulary of alchemy. The alchemists invented a process for making an airtight glass tube, which they used for distillation; the process used a secret seal, whose invention was attributed to an inspiration of alchemy, Hermes Trismegistus. Some kinds of packaging must maintain a seal against flow of gases: foods, some chemicals and some consumer goods; the term can describe food preservation practices, such as vacuum canning. Barrier packaging includes containers such as glass, aluminum cans, metal foils, high barrier plastics. Buildings designed with sustainable architecture principles use airtight technologies to conserve energy.
Under low energy building, passive house, low-energy house, self-sufficient homes, zero energy building, superinsulation standards, structures must be more air-tight than previously. Air barriers, careful sealing of construction joints and service penetrations achieve this. Airtightness minimizes the amount of warm air that can pass through the structure, so the mechanical ventilation system can recover the heat before discharging air externally. Green buildings may include windows that combine triple-pane insulated glazing with argon or krypton gas to reduce thermal conductivity and increase efficiency. In landscape and exterior construction projects, airtight seals protect general service and landscape lighting electrical connections and splices. Many other specific applications must meet airtight standards to be waterproof or vapor-proof for human safety and proper function. Applications for hermetic sealing include semiconductor electronics, optical devices, MEMS, switches, it is used for electrical or electronic parts that must be secure against water vapor and foreign bodies to maintain proper functioning and reliability.
Hermetic sealing for airtight conditions is used in archiving significant historical items. In 1951, The U. S. Constitution, U. S. Declaration of Independence, U. S. Bill of Rights were hermetically sealed with helium gas in glass cases housed in the U. S. National Archives in Washington, D. C.. In 2003, they were moved to new glass cases hermetically sealed with argon. Typical epoxy resins have pendant hydroxyl groups along their chain that can form bonds or strong polar attractions to oxide or hydroxyl surfaces. Most inorganic surfaces—i.e. Metals, glasses, ceramics—have polarity so they have high surface energy; the important factor in determining good adhesive strength is whether the surface energy of the substrate is close to or higher than the surface energy of the cured adhesive. Certain epoxy resins and their processes can create a hermetic bond to copper, brass, or epoxy itself with similar coefficients of thermal expansion, are used in the manufacture of hermetic electrical and fiber optic hermetic seals.
Epoxy hermetic seal designs can be used in hermetic seal applications for low or high vacuum or pressures sealing gases or fluids including helium gas to low helium gas leak rates similar to glass or ceramic. Hermetic epoxy seals offer the design flexibility of sealing either copper alloy wires or pins, instead of the much less electrically conductive Kovar pin materials required in glass or ceramic hermetic seals. Epoxy hermetic seal has a more limited operating temperature range compared to glass or ceramic seals with an operating range of -70°C to +125°C or 150°C, though some hermetic epoxy designs are capable of 200°C; when the glass and the metal being hermetically sealed have the same coefficient of thermal expansion, a "matched seal" derives its strength from bond between the glass and the metal's oxide. This type of glass-to-metal hermetic seal is the weaker of the two types and is used for low-intensity applications such as in light bulb bases. "Compression seals" occur when the glass and the metal have different coefficients of thermal expansion such that the metal compresses around the solidified glass as it cools.
Compression seals can withstand high pressure and are used in a variety of industrial applications. Co-fired ceramic seals are an alternative to glass. Ceramic seals exceed the design barriers of glass to metal seals due to superior hermetic performance in high stress environments requiring a robust seal. Choosing between glass versus ceramic depends on the application, thermal solution and material requirements. Glass taper joints can be sealed hermetically with PTFE sealing rings, o-rings, or PTFE sleeves, sometimes used instead of grease that can dissolve into contamination. PTFE tape, PTFE resin string, wax are other alternatives that are finding widespread use, but require a little care when winding onto the joint to ensure a good seal is produced. A thin layer of grease made for this application can be applied to the ground glass surfaces to be connected, the inner joint is inserted into the outer joint such that the ground glass surfaces of each are next to each other to make the connection.
In addition to making a leak-tight connection, the grease lets two joints be separated more easily. A potential drawback of such grease is that if used on laboratory glassware for a l
Siemens AG is a German multinational conglomerate company headquartered in Berlin and Munich and the largest industrial manufacturing company in Europe with branch offices abroad. The principal divisions of the company are Industry, Energy and Infrastructure & Cities, which represent the main activities of the company; the company is a prominent maker of medical diagnostics equipment and its medical health-care division, which generates about 12 percent of the company's total sales, is its second-most profitable unit, after the industrial automation division. The company is a component of the Euro Stoxx 50 stock market index. Siemens and its subsidiaries employ 379,000 people worldwide and reported global revenue of around €83 billion in 2018 according to its earnings release. Siemens & Halske was founded by Werner von Siemens and Johann Georg Halske on 12 October 1847. Based on the telegraph, their invention used a needle to point to the sequence of letters, instead of using Morse code; the company called Telegraphen-Bauanstalt von Siemens & Halske, opened its first workshop on 12 October.
In 1848, the company built the first long-distance telegraph line in Europe. In 1850, the founder's younger brother, Carl Wilhelm Siemens Sir William Siemens, started to represent the company in London; the London agency became a branch office in 1858. In the 1850s, the company was involved in building long distance telegraph networks in Russia. In 1855, a company branch headed by another brother, Carl Heinrich von Siemens, opened in St Petersburg, Russia. In 1867, Siemens completed the monumental Indo-European telegraph line stretching over 11,000 km from London to Calcutta. In 1867, Werner von Siemens described a dynamo without permanent magnets. A similar system was independently invented by Charles Wheatstone, but Siemens became the first company to build such devices. In 1881, a Siemens AC Alternator driven by a watermill was used to power the world's first electric street lighting in the town of Godalming, United Kingdom; the company diversified into electric trains and light bulbs. In 1887, it opened its first office in Japan.
In 1890, the founder retired and left running the company to his brother Carl and sons Arnold and Wilhelm. Siemens & Halske was incorporated in 1897, merged parts of its activities with Schuckert & Co. Nuremberg in 1903 to become Siemens-Schuckert. In 1907, Siemens had 34,324 employees and was the seventh-largest company in the German empire by number of employees. In 1919, S & H and two other companies jointly formed the Osram lightbulb company. During the 1920s and 1930s, S & H started to manufacture radios, television sets, electron microscopes. In 1932, Gebbert & Schall, Phönix AG and Siemens-Reiniger-Veifa mbH merged to form the Siemens-Reiniger-Werke AG, the third of the so-called parent companies that merged in 1966 to form the present-day Siemens AG. In the 1920s, Siemens constructed the Ardnacrusha Hydro Power station on the River Shannon in the Irish Free State, it was a world first for its design; the company is remembered for its desire to raise the wages of its under-paid workers only to be overruled by the Cumann na nGaedheal government.
Siemens exploited the forced labour of deported people in extermination camps. The company owned a plant in Auschwitz concentration camp. During the final years of World War II, numerous plants and factories in Berlin and other major cities were destroyed by Allied air raids. To prevent further losses, manufacturing was therefore moved to alternative places and regions not affected by the air war; the goal was to secure continued production of important everyday goods. According to records, Siemens was operating 400 alternative or relocated manufacturing plants at the end of 1944 and in early 1945. In 1972, Siemens sued German satirist F. C. Delius for his satirical history of the company, Unsere Siemenswelt, it was determined much of the book contained false claims although the trial itself publicized Siemens' history in Nazi Germany; the company supplied electrical parts to Nazi concentration camps and death camps. The factories had poor working conditions, where death were common; the scholarship has shown that the camp factories were created and supplied by the SS, in conjunction with company officials, sometimes high-level officials.
Siemens businessman and Nazi Party member John Rabe is, credited with saving many Chinese lives during the infamous Nanking Massacre. He toured Germany lecturing on the atrocities committed by Japanese forces in Nanking. In the 1950s, from their new base in Bavaria, S&H started to manufacture computers, semiconductor devices, washing machines, pacemakers. In 1966, Siemens & Halske, Siemens-Schuckertwerke and Siemens-Reiniger-Werke merged to form Siemens AG. In 1969, Siemens formed Kraftwerk Union with AEG by pooling their nuclear power businesses; the company's first digital telephone exchange was produced in 1980. In 1988, Siemens and GEC acquired the UK technology company Plessey. Plessey's holdings were split, Siemens took over the avionics and traffic control businesses—as Siemens Plessey. In 1985, Siemens bought Allis-Chalmers' interest in the partnership company Siemens-Allis which supplied electrical control equipment, it was incorporated into Siemens' Energy and Automation division. In 1987, Siemens reintegrated
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the
The Munich U-Bahn is an electric rail rapid transit network in Munich, Germany. The system began operation in 1971, is operated by the municipally owned Münchner Verkehrsgesellschaft; the network is integrated into the Münchner Verkehrs- und Tarifverbund and interconnected with the Munich S-Bahn. The U-Bahn comprises eight lines, serving 96 stations, encompassing 103.1 kilometres of routes. There are eight lines: The network has 103.1 kilometres of active route, 100 stations. In 2014, 390 million passengers rode the U-Bahn; the trains operate at speeds up to 80 kilometres per hour, the top speed among German U-Bahns. There is no continuous operation during the night except on special occasions such as New Year's Eve. Only the U6 line, crosses the municipal border to the town of Garching. Except for the lines U5 and U6, all lines operate below ground. U5 only comes above ground at the south terminus Neuperlach-Süd, U6 on the northern section from Studentenstadt. There are three "line families", which consist of two lines that share a common track in the city centre.
The schedules of these lines are coordinated in a way, which yields regular train intervals on the common section. Most stations have two tracks with an island platform between them. Of the single-line stations, only the stations Olympia-Einkaufszentrum, Richard-Strauss-Straße, Neuperlach Süd, Garching-Hochbrück and Nordfriedhof have side platforms. At the junction stations Scheidplatz and Innsbrucker Ring, the four tracks lie in parallel on the same level with two island platforms allowing cross-platform interchange; the stations Hauptbahnhof, where U1 and U2 branch into two different lines and Münchner Freiheit have four tracks, while Implerstraße, Max-Weber-Platz and Kolumbusplatz have three: one with a side platform for outbound trains and two with a shared island platform for inbound trains. Olympiazentrum, Fröttmaning and Kieferngarten have four tracks each, due to the proximity of the Olympic Stadium, the Allianz Arena football stadium, the technical base, respectively. At Hauptbahnhof, there is a second U-Bahn station for lines U4/5 at a higher level, giving a total of six U-Bahn tracks.
Sendlinger Tor and Olympia-Einkaufszentrum each have two stations at different levels being distinct stations on their own, connected with each other by escalators and elevators. Most lines operate with trains running at intervals of every 5 minutes during peak hours, but due to lines overlapping, a suitable train for a journey can be as frequent as every 2 minutes. Outside of peak times lines operate trains at frequencies of every 10 minutes. Again with line overlap. In 1980 the U1 commenced operation together with the U8. At the beginning it was only operating on a section of U2's track; when the branch to Rotkreuzplatz was opened, it became a separate line. The line's colour is green. Today the U1 has a length of 15 stations, it starts at Olympia-Einkaufszentrum in the district of Moosach. The U3 was extended to the same station in 2007. On the way south it follows Hanauer Straße to Georg-Brauchle-Ring, designed by Franz Ackermann, reaching Westfriedhof, it continues via Gern to Rotkreuzplatz, its terminus from 1983 to 1998.
Below Nymphenburger Straße it goes on to Maillingerstraße and Stiglmaierplatz and merges into the U2 track at München Hauptbahnhof. On the busy city section, U1 and U2 run with a 5-minute offset, yielding 5 minute intervals beyond peak hours. At Central Station, it crosses the S-Bahn and U4/U5. At the next station, Sendlinger Tor, it passes below U3/U6. There the U1/U2 platforms for each direction lie in tunnels which are apart from each other and are connected by a pedestrian tunnel. Fraunhoferstraße, the next station, is reached in separate tunnels, which had to be excavated using tunneling shields due to the proximity of the River Isar. However, the two tubes are connected by the platform, which demanded large pillars that are characteristic for this station; the next station, Kolumbusplatz, is a junction. Here the U1 branches off the U2 again; the southbound branch line was opened in 1997 and traverses the colourful station Candidplatz reaching Wettersteinplatz. The following station, St.-Quirin-Platz has an extraordinary architecture, as it is covered by a large, shell-like structure made from glass and steel, drawn nearly down to track level on one side.
The U1 terminates at Mangfallplatz below Naupliastraße. The route of the U2 line has undergone more changes than any of the other Munich underground lines, it changed its name as it was first called U8. It is the only line that runs or ran on all three "line families". Today it has a length of 27 stations; the line's colour is red. The U2 starts in the north at Feldmoching; the station there is decorated with urban motives of Feldmoching's history. Below Hasenbergl, a district, known for its social problems, it goes to Dül
InnoTrans is the world's largest trade fair focused on the rail transport industry. It is held every two years at the Messe Berlin exhibition centre, which has outdoor standard gauge railway sidings which can be used to exhibit railway vehicles. During the weekend after the trade show the public can visit the rolling stock on display. InnoTrans has grown in area and exhibitor numbers since it moved to Berlin in 1996. For the 2010 fair, organiser Messe Berlin Ltd announced an increase to 2,000 exhibitors from 44 countries, which covered the whole area of the exhibition centre for the first time. A spin-off supplementary exhibition "Public Transport Interiors" aimed at the mass transit sector was planned, but the first event announced for 2011 was postponed until a time. InnoTrans 2012 was instead the first to include a separate "Public Transport and Interiors Hall Forum", with a series of multimedia presentations on new design options in the industry. 2020 22 to 25 September 2020 in Berlin2018 18 to 21 September 2018 in Berlin 3062 exhibitors from 61 countries2016 20 to 23 September 2016 in Berlin.
Conference Corner where exhibitors and transport companies can hold lectures and present papers. 2955 exhibitors from 60 countries. The summer-garden yard is opened to allow a round driving course. For the first time all of the 41 exhibition halls of the fair ground are used which encompasses about 200.000 square meter, including 3500 meter of standard gauge track2014 23 to 26 September 2014 in Berlin More than 2700 exhibitors from 51 countries. An InnoTrans Daily newspaper will be produced by Railway Gazette International Messe Berlin has constructed a further exhibition hall called the CityCube Berlin. In addition to the general ten standard gauge tracks a Special Gauge Display allows to show broad gauge and narrow gauge vehicles. List of rolling stock on show.2012 18 to 21 September 2012 in Berlin InnoTrans still grows – there are expected to be 2450 exhibitors from 47 countries at InnoTrans 2012, which has five main segments: Railway Technology, Railway Infrastructure, Tunnel Construction and Public Transport.
More than 110,000 trade visitors are expected. An InnoTrans Daily newspaper will be produced by Railway Gazette International. List of rolling stock on show.2010 21 to 24 September 2010 in Berlin 2,242 exhibitors from 45 countries 106,612 trade visitors from 110 countries 81,000 square meters of exhibitions booths and 3,500 metres of railway track 121 vehicles on show2008 23 to 28 September in Berlin 1,912 exhibitors from 41 countries 80,000 trade visitors from 100 countries 150,000 square meters of exhibition area and 3,500 metres of railway track 91 vehicles on show. Contracts signed worth about €2 billion2006 19 to 22 September in Berlin 1,606 exhibitors from 41 countries 64,422 trade visitors from 90 countries 25,000 private visitors on the weekend public opening 50,591 square meters of exhibition area 2004 21 to 24 September in Berlin 1,369 exhibitors from 35 countries 44,968 trade visitors 40,468 square meters of exhibition area 2002 24 to 27 September in Berlin 1,045 exhibitors from 30 countries 35,686 trade visitors 29,469 square meters of exhibition area2000 12 to 15 September in Berlin 826 exhibitors 23,909 trade visitors 22,179 square meters of exhibition area1998 28 to 30 October in Berlin 403 exhibitors 13,164 trade visitors 10,534 square meters of exhibition area1996 15 to 20 October in Berlin 172 exhibitors 6,376 trade visitors 4,524 square meters of exhibition area Media related to InnoTrans at Wikimedia Commons InnoTrans website
A weighing scale is a device to measure weight or mass. These are known as mass scales, weight scales, mass balance, weight balance, or scale, balance, or balance scale; the traditional scale bowls suspended at equal distances from a fulcrum. One plate holds an object of unknown mass, while known masses are added to the other plate until static equilibrium is achieved and the plates level off, which happens when the masses on the two plates are equal. A spring scale will make use of a spring of known stiffness to determine mass. Suspending a certain mass will extend the spring by a certain amount depending on the spring's stiffness; the heavier the object, the more the spring stretches, as described in Hooke's law. Other types of scale making use of different physical principles exist; some scales can be calibrated to read in units of force such as newtons instead of units of mass such as kilograms. Scales and balances are used in commerce, as many products are sold and packaged by mass; the balance scale is such a simple device that its usage far predates the evidence.
What has allowed archaeologists to link artifacts to weighing scales are the stones for determining absolute mass. The balance scale itself was used to determine relative mass long before absolute mass; the oldest evidence for the existence of weighing scales dates to c. 2400–1800 B. C. in the Indus River valley. Prior to that, no banking was performed due to lack of scales. Uniform, polished stone cubes discovered in early settlements were used as mass-setting stones in balance scales. Although the cubes bear no markings, their masses are multiples of a common denominator; the cubes are made of many different kinds of stones with varying densities. Their mass, not their size or other characteristics, was a factor in sculpting these cubes. In Egypt, scales can be traced to around 1878 B. C. but their usage extends much earlier. Carved stones bearing marks denoting mass and the Egyptian hieroglyphic symbol for gold have been discovered, which suggests that Egyptian merchants had been using an established system of mass measurement to catalog gold shipments or gold mine yields.
Although no actual scales from this era have survived, many sets of weighing stones as well as murals depicting the use of balance scales suggest widespread usage. In China, the earliest weighing balance excavated was from a tomb of the State of Chu of the Chinese Warring States Period dating back to the 3rd to 4th century BC in Mount Zuojiagong near Changsha, Hunan; the balance was made of wood and used bronze masses. Variations on the balance scale, including devices like the cheap and inaccurate bismar, began to see common usage by c. 400 B. C. by many small merchants and their customers. A plethora of scale varieties each boasting advantages and improvements over one another appear throughout recorded history, with such great inventors as Leonardo da Vinci lending a personal hand in their development. With all the advances in weighing scale design and development, all scales until the seventeenth century AD were variations on the balance scale; the standardization of the weights used – and ensuring traders used the correct weights – was a considerable preoccupation of governments throughout this time.
The original form of a balance consisted of a beam with a fulcrum at its center. For highest accuracy, the fulcrum would consist of a sharp V-shaped pivot seated in a shallower V-shaped bearing. To determine the mass of the object, a combination of reference masses was hung on one end of the beam while the object of unknown mass was hung on the other end. For high precision work, such as empirical chemistry, the center beam balance is still one of the most accurate technologies available, is used for calibrating test masses; the balance was the first mass measuring instrument invented. In its traditional form, it consists of a pivoted horizontal lever with arms of equal length – the beam – and a weighing pan suspended from each arm; the unknown mass is placed in one pan and standard masses are added to the other pan until the beam is as close to equilibrium as possible. In precision balances, a more accurate determination of the mass is given by the position of a sliding mass moved along a graduated scale.
Technically, a balance compares weight rather than mass, but, in a given gravitational field, the weight of an object is proportional to its mass, so the standard masses used with balances are labeled in units of mass. Unlike spring-based scales, balances are used for the precision measurement of mass as their accuracy is not affected by variations in the local gravitational field. A change in the strength of the gravitational field caused by moving the balance does not change the measured mass, because the moments of force on either side of the beam are affected equally. A balance will render an accurate measurement of mass at any location experiencing a constant gravity or acceleration. Precise measurements are achieved by ensuring that the balance's fulcrum is friction-free, by attaching a pointer to the beam which amplifies any deviation from a balance position. For greatest accuracy, there needs to be an allowance for the bu