Misplaced Pages

#830169

46-519: Although the marble through which the tunnels are dug is considered " hard rock ", at the great depth it presents greater geotechnical engineering challenges than the even harder igneous rocks in which other deep laboratories are constructed. The 10 MPa (1500 psi; 99 atm) water pressure in the rock is also inconvenient. But marble has the advantage for radiation shielding of being low in radionuclides , such as K , Ra , Th , and U . This in turn leads to low levels of radon ( Rn ) in

92-476: A recommended exposure limit (REL) of 10 mg/m total exposure and 5 mg/m respiratory exposure over an 8-hour workday. Dust, debris and temperature fluctuations from working marble can endanger the eye health of employees. For the staff involved in marble processing, it is necessary to provide eye protection equipment, and it is recommended to improve the education of all workers on occupational health risks and strengthen preventive measures. As

138-532: A fifth for facilities). There is likewise no shortage of water for cooling high-powered equipment. The muon flux in (and thus water equivalent depth of) CJPL-II is currently being measured, and may differ slightly from CJPL-I, but it will certainly remain lower than SNOLAB in Canada and thus retain the record for the world's deepest laboratory as well. Experiments currently operating in CJPL are: Also operating in

184-570: A growth of 12% annually for the 2000–2006 period, compared to 10.5% annually for the 2000–2005 period. The largest dimension marble application is tile. The stone and marble industry is one of the largest industries in Palestine, contributing 20-25% of its total industrial revenues, generating USD $ 400–$ 450 million in revenue annually. The industry employs 15,000–20,000 workers across the West Bank across 1200–1700 facilities, and amounts to 4.5% of

230-488: A large amount of waste not being land-filled, reducing environmental pollution, thereby realizing the sustainability of marble. Converting waste to generate economic income and restore degraded soil can improve the environment. The nature of marble is soft and porous, so it is easily stained by colored liquids and scratches easily. Maintenance and cleaning is particularly important. Volt-ampere The volt-ampere ( SI symbol : VA , sometimes V⋅A or V A )

276-420: A new apparent power ( S ), measured in volt-amperes: The relationship between real power and apparent power is described by the power factor . With a purely resistive load, they are the same: the apparent power is equal to the real power. Where a reactive (capacitive or inductive) component is present in the load, the apparent power is greater than the real power as voltage and current are no longer in phase. In

322-646: A potential hazard. Mitigations such as dust filters, or dust suppression are suggested, but more research needs to be carried out on the efficacy of safety measures. In the United States, the Occupational Safety and Health Administration (OSHA) has set the legal limit ( permissible exposure limit ) for marble exposure in the workplace as 15 mg/m total exposure and 5 mg/m respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set

368-441: A second were made quickly, before the excavation workers and equipment departed following completion of the hydroelectric project in 2014. Slightly west of CJPL-I, two bypass tunnels totalling roughly 1 km (3,300 ft) long are left over from constructing the seven tunnels of the hydropower project. They are sloped criss-crossing tunnels which connect the midpoints of the five water tunnels (four headrace and one drainage) to

414-425: A typical process using magnesium fluorosilicate (MgSiF 6 ) and hydrochloric acid (HCl) taking place. The resulting calcium hexafluorosilicate (CaSiF 6 ) is bonded to the surface of the marble. This is harder, more glossy and stain resistant compared to the original surface. The other often used method of finishing marble is to polish with oxalic acid (H 2 C 2 O 4 ), an organic acid. The resulting reaction

460-399: Is a rock composed of calcium and magnesium carbonate , mostly white and pink. Common marble varieties are granular limestone or dolomite . The hardness of marble is very high, because the internal structure of the rock is very uniform after long-term natural aging, and the internal stress disappears, so the marble will not be deformed due to temperature, and has strong wear resistance. It

506-439: Is a very popular building material. The following table is a summary of the features of Marble. White marble has been prized for its use in sculptures since classical times . This preference has to do with its softness, which made it easier to carve, relative isotropy and homogeneity, and a relative resistance to shattering. Also, the low index of refraction of calcite allows light to penetrate 12.7 to 38 millimeters into

SECTION 10

#1732793248831

552-538: Is as follows: In this case the calcium oxalate (CaC 2 O 4 ) formed in the reaction is washed away with the slurry, leaving a surface that has not been chemically changed. The haloalkaliphilic methylotrophic bacterium Methylophaga murata was isolated from deteriorating marble in the Kremlin . Bacterial and fungal degradation was detected in four samples of marble from Milan Cathedral ; black Cladosporium attacked dried acrylic resin using melanin. Marble

598-758: Is somewhat behind expectations that they would be ready for occupation in January 2017.) When complete, it will be the world's largest underground laboratory, surpassing the current record-holder the Laboratori Nazionali del Gran Sasso (LNGS). Although greater depth and weaker rock force the halls to be narrower than the 20 m (66 ft) wide main halls of LNGS, their combined length of 520 m (1,710 ft) provides more floor space ( 7,280 vs. 6,000 m ) than LNGS's three halls totalling 300 metres (980 ft). CJPL's halls also enclose more volume than those of LNGS. CJPL has 93,300 m in

644-399: Is that the walls of CJPL-I were lined with ordinary concrete taken from the hydroelectric project's supply. This has a natural radioactivity higher than desirable for a low-background laboratory. The second phase of construction uses materials selected for low radioactivity. The laboratory is currently undergoing a major (50-fold) expansion. The first phase was rapidly filled, and plans for

690-422: Is the unit of measurement for apparent power in an electrical circuit . It is the product of the root mean square voltage (in volts ) and the root mean square current (in amperes ). Volt-amperes are usually used for analyzing alternating current (AC) circuits. In direct current (DC) circuits, this product is equal to the real power , measured in watts . The volt-ampere is dimensionally equivalent to

736-581: The Ancient Greek μάρμαρον ( mármaron ), from μάρμαρος ( mármaros ), "crystalline rock, shining stone", perhaps from the verb μαρμαίρω ( marmaírō ), "to flash, sparkle, gleam"; R. S. P. Beekes has suggested that a " Pre-Greek origin is probable". This stem is also the ancestor of the English word "marmoreal", meaning "marble-like." While the English term "marble" resembles

782-552: The French marbre , most other European languages (with words like "marmoreal") more closely resemble the original Ancient Greek. Marble is a rock resulting from metamorphism of sedimentary carbonate rocks , most commonly limestone or dolomite . Metamorphism causes variable re-crystallization of the original carbonate mineral grains. The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals . Primary sedimentary textures and structures of

828-493: The dimension stone trade, the term marble is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone. For example, Tennessee marble is really a dense granular fossiliferous gray to pink to maroon Ordovician limestone, that geologists call the Holston Formation . Ashgabat , the capital city of Turkmenistan , was recorded in the 2013 Guinness Book of Records as having

874-484: The watt : in SI units , 1 V⋅A = 1 W. VA rating is most used for generators and transformers, and other power handling equipment, where loads may be reactive (inductive or capacitive). For a simple electrical circuit running on direct current , the electrical current and voltage are constant. In that case, the real power ( P , measured in watts ) is the product of the current ( I , measured in amperes ) and

920-652: The atmosphere. The laboratory is in Liangshan in southern Sichuan, about 500 km (310 mi) southwest of Chengdu . The closest major airport is Xichang Qingshan Airport , 120 km (75 mi) away by road. The Jinping-II Dam hydroelectric power project involved excavating a number of large tunnels under the Jinping Mountains : four large 16.7 km (10.4 mi) headrace tunnels carrying water east, two 17.5 km (10.9 mi) vehicular access tunnels, and one water drainage tunnel. Hearing of

966-439: The device. When a UPS powers equipment which presents a reactive load with a low power factor, neither limit may safely be exceeded. For example, a (large) UPS system rated to deliver 400,000 volt-amperes (400 kVA) at 220 volts can deliver a current of 1818 amperes (these are RMS values). VA ratings are also often used for transformers; maximum output current is then VA rating divided by nominal output voltage. Transformers with

SECTION 20

#1732793248831

1012-487: The excavated material will be waste, this is often then used as chips for flooring or wall finish, and uses for which high-calcium limestone is suitable. Marble sludge waste can be used as a mineral filler in water-based paints. Using ground calcium carbonate as a filler in paint production can improve the brightness, hiding power and application performance of paint, and can also replace expensive pigments such as titanium dioxide . Recycling of marble waste leads to

1058-607: The excavation in August 2008, physicists at Tsinghua University determined that it would be an excellent location for a deep underground laboratory, and negotiated with the hydropower company to excavate laboratory space in the middle of the tunnels. A formal agreement was signed on 8 May 2009, and excavation was promptly started. The first phase CJPL-I , consisting of a 6.5 × 6.5 × 42 m (21 × 21 × 138 ft) main hall, plus 55 m (180 ft) of access tunnel (4,000 m total excavation)

1104-454: The favorite medium for Greek and Roman sculptors and architects (see classical sculpture ), marble has become a cultural symbol of tradition and refined taste. Its extremely varied and colorful patterns make it a favorite decorative material. Places named after the stone include Marblehead, Massachusetts ; Marblehead, Ohio ; Marble Arch , London; the Sea of Marmara ; India's Marble Rocks ; and

1150-437: The formation of "black-crust" (accumulation of calcium sulphate, nitrates and carbon particles). Vinegar and other acidic solutions should be avoided in the cleaning of marble products. Crystallization refers to a method of imparting a glossy, more durable finish on to a marble floor (CaCO 3 ). It involves polishing the surface with an acidic solution and a steel wool pad on a flooring machine. The chemical reaction below shows

1196-450: The halls proper, and an additional 9,300 m in the shielding pits making a total of 102,600 m , slightly more than LNGS's 95,100 m . Including the service areas outside the main halls, the result is 200,000–300,000 m of usable space, more than LNGS's grand total of 180,000 m . CJPL's total volume of 361,000 m would suggest that CJPL is twice the size, but that would be misleading; all of LNGS's excavation

1242-461: The halls' floors. The China Dark Matter Experiment has a cylindrical pit, 18 m (59 ft) deep and in diameter, which will be filled with a liquid nitrogen tank, and PandaX has an elliptical pit for a water shielding tank, 27×16 m (89×52 ft) and 14 m (46 ft) deep. The halls were complete by the end of 2015,, the pits by May 2016, and as of May 2017 are being fitted with ventilation systems and other necessities. (This

1288-402: The influence of heat and pressure. It has a crystalline texture, and is typically not foliated ( layered ), although there are exceptions. In geology , the term marble refers to metamorphosed limestone , but its use in stonemasonry more broadly encompasses unmetamorphosed limestone. Marble is commonly used for sculpture and as a building material . The word "marble" derives from

1334-550: The laboratory is a low background facility using a high purity germanium detector , for measuring very low levels of radioactivity. This is not a physics experiment itself, but tests materials intended for use in the experiments. It also tests materials used to construct CJPL-II. Experiments currently planned for CJPL-II are: Proposals also exist for: Marble Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO 3 ) or dolomite (CaMg(CO 3 ) 2 ) that have recrystallized under

1380-566: The limestone. Green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolomite with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism. Acids react with the calcium carbonate in marble, producing carbonic acid (which decomposes quickly to CO 2 and H 2 O) and other soluble salts : Outdoor marble statues, gravestones , or other marble structures are damaged by acid rain whether by carbonation , sulfation or

1426-413: The limiting case of a purely reactive load, current is drawn but no power is dissipated in the load. Some devices, including uninterruptible power supplies (UPSs), have ratings both for maximum volt-amperes and maximum watts. A common prefixed derived unit is "kilovolt-ampere" (symbol kVA). The VA rating is limited by the maximum permissible current, and the watt rating by the power-handling capacity of

China Jinping Underground Laboratory - Misplaced Pages Continue

1472-546: The nation's GDP. The vast majority of the industry's exports are to Israel. Marble in the geologic sense does not naturally outcrop in Palestine, and that the vast majority of commercially labeled marble produced in Palestine produced would be geologically considered limestone. Particulate air pollution exposure has been found to be elevated in the marble production industry. Exposure to the dust produced by cutting marble could impair lung function or cause lung disease in workers, such as silicosis . Skin and eye problems are also

1518-460: The original carbonate rock ( protolith ) have typically been modified or destroyed. Pure white marble is the result of metamorphism of a very pure ( silicate -poor) limestone or dolomite protolith. The characteristic swirls and veins of many colored marble varieties, sometimes called striations , are usually due to various mineral impurities such as clay , silt , sand , iron oxides , or chert which were originally present as grains or layers in

1564-508: The road tunnels beside and slightly above them. Totalling 210,000 m (7.4 × 10 ^  cu ft), and originally intended to be blocked off after construction, they have been donated to the laboratory and will be used for support facilities. The expansion has added 151,000 m (5.3 × 10 ^  cu ft), of additional excavation : some interconnecting access tunnels, four large experimental halls, each 14×14×130 m (46×46×427 ft), and two pits for shielding tanks below

1610-453: The same sized core usually have the same VA rating. The convention of using the volt-ampere to distinguish apparent power from real power is allowed by the SI standard. In electric power transmission and distribution , volt-ampere reactive ( var ) is a unit of measurement of reactive power . Reactive power exists in an AC circuit when the current and voltage are not in phase. The term var

1656-409: The stone before being scattered out, resulting in the characteristic waxy look which brings a lifelike luster to marble sculptures of any kind, which is why many sculptors preferred and still prefer marble for sculpting the human form. Construction marble is a stone which is composed of calcite, dolomite or serpentine that is capable of taking a polish. More generally in construction , specifically

1702-679: The towns of Marble, Minnesota ; Marble, Colorado ; Marble Falls, Texas , and Marble Hill, Manhattan, New York . The Elgin Marbles are marble sculptures from the Parthenon in Athens that are on display in the British Museum . Total world quarrying production in 2019 was approximately 316 million tonnes; however, quarrying waste accounted for 53% of this total production. In the process of marble mining and processing, around half or

1748-590: The voltage from one side of the circuit to the other ( V , measured in volts ): For alternating current , both the voltage and current are oscillating. Instantaneous power is still the product of instantaneous current and instantaneous voltage, but if both of those are ideal sine waves driving a purely resistive load (like an incandescent light bulb), average power becomes (with subscripts designating average (av), peak amplitude (pk) and root mean square (rms)): More generally, when voltage and current are not in phase, these products no longer represent average power but

1794-655: The widespread exchange of marble objects, including building elements, sculptures, and sarcophagi . There was a significant increase in the distribution of white marble from the late 1st century BC to the end of the 2nd century AD. A gradual decline in distribution started in the third century AD. According to the United States Geological Survey , U.S. domestic marble production in 2006 was 46,400 tons valued at about $ 18.1 million, compared to 72,300 tons valued at $ 18.9 million in 2005. Crushed marble production (for aggregate and industrial uses) in 2006

1840-415: The world's highest concentration of white marble buildings. The extraction of marble is performed by quarrying . Blocks are favoured for most purposes, and can be created through various techniques, including drilling and blasting, water jet and wedge methods. Limestones are often commercially and historically referred to as marble, which differs from the geological definition. In 1998, marble production

1886-753: Was China with a 64% market share, followed by India with 11% and Italy with 5%. White marbles throughout the Mediterranean basin were widely utilized during the Roman period. Extraction centers were unevenly distributed across the Italian Peninsula , mainland Greece , the Aegean Islands , Asia Minor , and smaller hubs like those in the Iberian Peninsula . The need for extensive trade arose due to this imbalance, leading to

China Jinping Underground Laboratory - Misplaced Pages Continue

1932-465: Was 11.8 million tons valued at $ 116 million, of which 6.5 million tons was finely ground calcium carbonate and the rest was construction aggregate . For comparison, 2005 crushed marble production was 7.76 million tons valued at $ 58.7 million, of which 4.8 million tons was finely ground calcium carbonate and the rest was construction aggregate. U.S. dimension marble demand is about 1.3 million tons. The DSAN World Demand for (finished) Marble Index has shown

1978-441: Was designed to be a laboratory, and thus can be used more efficiently than CJPL's repurposed tunnels. Thanks to the laboratory's location within a major hydroelectric facility, additional electrical power is readily available. CJPL-II is supplied by two redundant 10 kV, 10  MVA power cables; available power is temporarily limited by the 5×250 kVA step-down transformers in the laboratory (one per experiment hall, and

2024-447: Was dominated by 4 countries that accounted for almost half of world production of marble and decorative stone. Italy and China were the world leaders, each representing 16% of world production, while Spain and India produced 9% and 8%, respectively. In 2018 Turkey was the world leader in marble export, with 42% share in global marble trade, followed by Italy with 18% and Greece with 10%. The largest importer of marble in 2018

2070-493: Was excavated by May 2010, and construction completed 12 June 2010. A formal laboratory inauguration was held 12 December 2010. The laboratory is to the south of the southernmost of the seven parallel tunnels, traffic tunnel A. The air ventilation in CJPL-I was initially inadequate, resulting in the accumulation of dust on the equipment and radon gas in the air until additional ventilation was installed. A more difficult problem

2116-756: Was proposed by the Romanian electrical engineer Constantin Budeanu and introduced in 1930 by the IEC in Stockholm , which has adopted it as the unit for reactive power. Special instruments called varmeters are available to measure the reactive power in a circuit. The unit "var" is allowed by the International System of Units (SI) even though the unit var is representative of a form of power. Per EU directive 80/181/EEC (the "metric directive"),

#830169