Misplaced Pages

#142857

50-619: Karamay was the site of one of the worst disasters in modern Chinese history, the 1994 Karamay fire , when 324 people, including 288 school children, lost their lives in a cinema fire on 8 December 1994. Karamay City has jurisdiction over four districts ( 区 ; qū ). They are not contiguous as Dushanzi District is located south of the Lanxin Railway and forms an exclave, separated from the rest of Karamay City by Kuytun City . Together with Kuytun City, Karamay City forms an enclave surrounded on all sides by Tacheng Prefecture . Karamay

100-420: A sounding board , the vibration is amplified and heard in the second space. A mechanical transmission is much faster, more efficient and more readily amplified than an airborne transmission of the same initial strength. The use of acoustic foam and other absorbent means is less effective against this transmitted vibration. The transmission can be stopped by breaking the connection between the room that contains

150-520: A cavity, enclosure or room. Synthetic absorption materials are porous, referring to open cell foam (acoustic foam, soundproof foam). Fibrous absorption material such as cellulose, mineral wool, fiberglass, sheep's wool, are more commonly used to deaden resonant frequencies within a cavity (wall, floor, or ceiling insulation), serving a dual purpose along with their thermal insulation properties. Both fibrous and porous absorption material are used to create acoustic panels , which absorb sound reflections in

200-416: A hard flat surface is giving a problematic echo then an acoustic diffuser may be applied to the surface. It will scatter sound in all directions. In active noise control , a microphone is used to pick up the sound that is then analyzed by a computer; then, sound waves with opposite polarity (180° phase at all frequencies) are output through a speaker, causing destructive interference and canceling much of

250-424: A medium, the reflection of that sound is dependent on the dissimilarity of the material it comes in contact with. Sound hitting a concrete surface will result in a much different reflection than if the sound were to hit a softer medium such as fiberglass. In an outdoor environment such as highway engineering, embankments or paneling are often used to reflect sound upwards into the sky. If a specular reflection from

300-425: A number of factors including cell size, tortuosity , porosity, thickness, and density. The absorption aspect in soundproofing should not be confused with sound-absorbing panels used in acoustic treatments. Absorption in this sense refers to reducing a resonating frequency in a cavity by installing insulation between walls, ceilings or floors. Acoustic panels can play a role in treatment reducing reflections that make

350-496: A preliminary step for ceiling soundproofing. Acoustical caulk should be used along the perimeter of the wall and around all fixtures and duct registers to further seal the treatment. Mineral wool insulation is most commonly used in soundproofing for its density and low cost compared to other soundproofing materials. Spray foam insulation should only be used to fill gaps and cracks or as a 1-2 inch layer before installing mineral wool. Cured spray foam and other closed-cell foam can be

400-445: A research study conducted by Applied Science revealed 86% of students perceived their instructors more intelligibly, while 66% of students reported experiencing higher concentration levels after sound-absorbing materials were incorporated into the classroom. Automotive soundproofing aims to decrease or eliminate the effects of exterior noise, primarily engine, exhaust and tire noise across a wide frequency range. A panel damping material

450-418: A room, improving speech intelligibility. Porous absorbers, typically open cell rubber foams or melamine sponges , absorb noise by friction within the cell structure. Porous open cell foams are highly effective noise absorbers across a broad range of medium-high frequencies. Performance can be less impressive at lower frequencies. The exact absorption profile of a porous open-cell foam will be determined by

500-694: A second interior window. In this case, the exterior window remains in place while a slider or hung window is installed within the same wall openings. In the US, the FAA offers sound-reducing for homes that fall within a noise contour where the average sound level is 65  dB SPL or greater. It is part of their Residential Sound Insulation Program. The program provides solid-core wood entry doors plus windows and storm doors. Sealing gaps and cracks around electrical wiring, water pipes and ductwork using acoustical caulk or spray foam will significantly reduce unwanted noise as

550-462: A sound conductor. Spray foam is not porous enough to absorb sound and is also not dense enough to stop sound. An effective method to reduce impact noise is the "resilient isolation channel". The channels decouple the drywall from the joists, reducing the transfer of vibration. Mass is the only way to stop sound. Mass refers to drywall, plywood or concrete. Mass-loaded vinyl (MLV) is used to dampen or weaken sound waves between layers of mass. Use of

SECTION 10

#1732783520143

600-441: A sound source and any form of adjoining mass, hindering the direct pathway for sound transfer. The energy density of sound waves decreases as they become farther apart so increasing the distance between the receiver and source results in a progressively lesser intensity of sound at the receiver. In a normal three-dimensional setting, with a point source and point receptor, the intensity of sound waves will be attenuated according to

650-826: A vibrating structure. Several studies have revealed the potential of particle velocity sensors for characterizing structural vibrations, which accelerates the entire testing process when combined with scanning techniques. Since the early 1970s, it has become common practice in the United States and other industrialized countries to engineer noise barriers along major highways to protect adjacent residents from intruding roadway noise . The Federal Highway Administration (FHWA) in conjunction with State Highway Administration (SHA) adopted Federal Regulation (23 CFR 772) requiring each state to adopt their own policy in regards to abatement of highway traffic noise. Engineering techniques have been developed to predict an effective geometry for

700-482: A viscoelastic compound may achieve a noise reduction of STC 60+. Walls are filled with mineral wool insulation. Depending on the desired level of treatment, two layers of insulation may be required. Outlets, light switches, and electrical boxes are weak points in any given soundproofing treatment. Electrical boxes should be wrapped in clay or putty and backed with MLV . After switch plates, outlet covers and lights are installed, acoustical caulking should be applied around

750-403: A viscoelastic damping compound or MLV converts sound waves into heat, weakening the waves before they reach the next layer of mass. It is important to use multiple layers of mass, in different widths and densities, to optimize any given soundproofing treatment. Installing soundproof drywall is recommended for its higher sound transmission class (STC) value. Soundproof drywall in combination with

800-504: Is 401,468. In 1955, one of the largest oil fields in China was discovered there. Since then, the city has grown into an oil-producing and refining center. In 2008, the GDP reached ¥ 66.1 billion and GDP per capita reached ¥ 242,391 (US$ 34,901), ranking first among 659 cities in mainland China. 1994 Karamay fire The Karamay fire ( Chinese : 克拉玛依大火 ) of 8 December 1994 at

850-468: Is fitted which reduces the vibration of the vehicle's body panels when they are excited by one of the many high-energy sound sources in play when the vehicle is in use. There are many complex noises created within vehicles which change with the driving environment and speed at which the vehicle travels. Significant noise reductions of up to 8 dB can be achieved by installing a combination of different types of materials. The automotive environment limits

900-503: Is generous, only occurring less than 50% of the time in November and December and the annual average total is 2,694 hours. According to the 2010 census, over 80% of Karamay's population are Han Chinese , with minorities such as Uighur , Kazakhs , Mongols and Hui making up the rest. The population of 2010 is 391,008, a rise from the 270,232 of 2000 census. The population density is 50.6 inhabitants per km. The 2015 population estimate

950-485: Is located in the northwest of the Dzungarian basin, with an average elevation of 400 meters (1,300 ft). Its administrative area ranges in latitude from 44° 07' to 46° 08' N and in longitude from 80° 44' to 86° 01' E and has a maximal 240 km (150 mi) north–south extent and reaches 110 km (68 mi) in east–west width. It borders Hoboksar Mongol Autonomous County to the northeast, Shawan County to

1000-473: Is the lack of a seal at the edge of the curtain, although this may be alleviated with the use of sealing features, such as hook and loop fastener, adhesive, magnets, or other materials. The thickness of glass will play a role when diagnosing sound leakage. Double-pane windows achieve somewhat greater sound damping than single-pane windows when well-sealed into the opening of the window frame and wall. Significant noise reduction can also be achieved by installing

1050-697: Is −15.2 °C (4.6 °F) in January and soars to 27.8 °C (82.0 °F) in July and the annual mean is 8.91 °C (48.0 °F), warmer than most places at the corresponding latitude, due to the long summers. Annual precipitation is 119 millimeters (4.69 in) and the summer months record the most rainfall, despite relative humidity levels averaging around 30%. With monthly percent possible sunshine ranging from 37% in December to 71% in September, sunshine

SECTION 20

#1732783520143

1100-400: The inverse square of the distance from the source. Adding dense material to treatment helps stop sound waves from exiting a source wall, ceiling or floor. Materials include mass-loaded vinyl, soundproof sheetrock or drywall, plywood, fibreboard , concrete or rubber. Different widths and densities in soundproofing material reduce sound within a variable frequency range. When sound waves hit

1150-685: The sound waves , using damping structures such as sound baffles for absorption , or using active antinoise sound generators. Acoustic quieting and noise control can be used to limit unwanted noise. Soundproofing can reduce the transmission of unwanted direct sound waves from the source to an involuntary listener through the use of distance and intervening objects in the sound path (see sound transmission class and sound reduction index ). Soundproofing can suppress unwanted indirect sound waves such as reflections that cause echoes and resonances that cause reverberation . Sound-absorbing material controls reverberant sound pressure levels within

1200-522: The Friendship Theatre in Karamay , Xinjiang , China, was among the most notorious fires in China . Its notoriety derives partly from the fact that that the schoolchildren, who were entertaining visiting officials, were ordered to remain seated when the fire started to allow the visiting officials to walk out first. The fire killed 325, including 288 schoolchildren. The Friendship Theatre

1250-408: The beginning of the performance, as a manner of respect to them when the performance ends and China Youth Daily took the original sentence out of context. Notably, in the documentary Karamay , in an interview conducted in the hospital immediately after the fire, none of the interviewees spoke about the students being instructed to let the leaders go first. The Guangxi Fire Department has argued that

1300-435: The body in white structures enabling the fast acquisition of a large number of measurement points with a good spatial resolution. However, testing a complete vehicle is mostly infeasible, requiring evaluation of every subsystem individually, hence limiting the usability of this technology in a fast and efficient way. Alternatively, structural vibrations can also be acoustically measured using particle velocity sensors located near

1350-705: The dead and injured sent representatives to the National People's Congress in Beijing , supposedly the venue for Chinese citizens to seek justice and a fair hearing. They were led off by security guards to a walled government compound, where five buses took them back to the airport. The group were then escorted through special channels to a plane bound for Xinjiang. A court convicted a total of 13 people. Four of them, senior officials, were convicted of dereliction of duty and sentenced up to five years in prison. Others were convicted of lesser crimes while Zhao Zheng

1400-423: The evacuation issues were caused by panic, with people trying to escape through the doors from which they entered instead of the less crowded doors E and F. Additionally, the anti-robbery bars installed significantly hampered evacuation through windows and other doors. A total of 325 deaths were reported, with 288 of them being school children. Out of 25 officials, 17 died at the scene. In 1995, 300 families of

1450-457: The expansion of the usage of these materials to the automotive industry. Nowadays, multiple viscoelastic damping pads are usually attached to the body in order to attenuate higher-order structural panel modes that significantly contribute to the overall noise level inside the cabin. Traditionally, experimental techniques are used to optimize the size and location of damping treatments. In particular, laser vibrometer-type tests are often conducted on

1500-514: The fire was starved of oxygen, though it continued to burn, eventually burning through the electrical wiring and causing a blackout in the theatre. The students, who had previously remained seated started panicking to exit the theatre. At some point after the blackout, the supporting frame for the stage curtains collapsed, causing oxygen to rush into the previously starved fire, creating a backdraft reaching up to 1200 °C at 60 ATM . First response consisted of four fire brigade trucks, however,

1550-479: The fire, high up in the curtains. In 1995, the China Youth Daily was the first to have reported that somebody had asked the students 'let the leaders leave first' ( 让领导先走 ). The phrase has since become a catch phrase, meaning the government officials have priority over ordinary folks in times of emergency. As such, this fire remains the most notorious fire in China . Online articles identified

Karamay - Misplaced Pages Continue

1600-459: The firefighters who arrived on scene first did not have proper respiratory equipment and thus struggled in the toxic environment, resulting in 27 injuries to firefighters due to the smoke. The fire crews also lacked powered equipment, with each fire truck having only one fire axe; the fire pump pressure around the hall was also lacking. The dry powder fire extinguishers in the theatre, though potent against chemical fires, were wholly useless against

1650-529: The front hall. This unmarked memorial still stands in what is now the People's Park in the center of Karamay. There is no plaque or memorial anywhere in Karamay that references the deadly fire. Popular Chinese folk singer Zhou Yunpeng (周云蓬) has compiled a list of Chinese man-made disasters and turned it into a song, and the Karamay fire incident was mentioned in the song, as was the internet catch phrase, "Let

1700-411: The leaders walk out first." ( 让领导先走 ) 45°36′03″N 84°52′05″E  /  45.60083°N 84.86806°E  / 45.60083; 84.86806 Soundproofing Soundproofing is any means of impeding sound propagation . There are several methods employed including increasing the distance between the source and receiver, decoupling, using noise barriers to reflect or absorb the energy of

1750-515: The noise source and the outside world. This is called acoustic decoupling. Restaurants, schools, office businesses, and healthcare facilities use architectural acoustics to reduce noise for their customers. In the United States, OSHA has requirements regulating the length of exposure of workers to certain levels of noise. For educators and students, improving the sound quality of an environment will subsequently improve student learning, concentration, and teacher-student inter-communications. In 2014,

1800-535: The noise. Residential sound programs aim to decrease or eliminate the effects of exterior noise. The main focus of a residential sound program in existing structures is the windows and doors. Solid wood doors are a better sound barrier than hollow doors. Curtains can be used to dampen sound, either through use of heavy materials or through the use of air chambers known as honeycombs . Single-, double- and triple-honeycomb designs achieve relatively greater degrees of sound damping. The primary soundproofing limit of curtains

1850-400: The official as Kuang Li ( 况丽 ), the vice-director of the state petroleum company's local education centre, without official confirmation of this. By the time the leaders had filed out of the only open emergency exit, the other exits remained locked, preventing many teachers and pupils from escaping. Other survivors agreed that while 'let the leaders go first' was indeed said, it was spoken at

1900-436: The overall sound in the source room louder, after walls, ceilings, and floors have been soundproofed. Resonant panels, Helmholtz resonators and other resonant absorbers work by damping a sound wave as they reflect it. Unlike porous absorbers, resonant absorbers are most effective at low-medium frequencies and the absorption of resonant absorbers is matched to a narrow frequency range. Damping serves to reduce resonance in

1950-558: The perimeter of the plates or fixtures. Decoupling between the joist and subfloor plywood using neoprene joist tape or u-shaped rubber spacers helps create soundproof flooring. An additional layer of plywood can be installed with a viscoelastic compound. Mass loaded vinyl , in combination with open-cell rubber or a closed-cell foam floor underlayment, will further reduce sound transmission. After applying these techniques, hardwood flooring or carpeting can be installed. Additional area rugs and furniture will help reduce unwanted reflection within

2000-415: The room , by absorption or redirection through reflection or diffusion. Absorption reduces the overall sound level, whereas redirection makes unwanted sound harmless or even beneficial by reducing coherence . Damping can be separately applied to reduce the acoustic resonance in the air or to reduce mechanical resonance in the structure of the room itself or things in the room. Creating separation between

2050-421: The room. A room within a room (RWAR) is one method of isolating sound and preventing it from transmitting to the outside world where it may be undesirable. Most sound transfer from a room to the outside occurs through mechanical means. The vibration passes directly through the brick, woodwork and other solid structural elements. When it meets with an element such as a wall, ceiling, floor or window, which acts as

Karamay - Misplaced Pages Continue

2100-403: The second row noticed a burning smell; while the stage workers had realised the seriousness, much of the audience believed that it was part of the special effects and remained seated. Unlike the previous fire, the two electricians who operated the curtains were not available, being on a business trip to Ürümqi . Eventually, the main stage curtains were closed, concealing the fire from the audience;

2150-723: The southeast, Toli County and Wusu to the west and Kuytun to the south. The naturally available water supply in the Karamay area is limited: it mostly consists of two small rivers (the Baiyang River and the Da'erbute River ( 达尔不特河 ) flowing into the Dzungarian Basin from the mountains of its northwestern rim. In addition, the city receives water from the Irtysh River , over the Irtysh–Karamay Canal , which

2200-404: The stage curtains. Due to a lack of awareness on fire safety, the refurbishments of the theatre introduced many flammable objects, such as the seats, which due to being made from artificial fibres, burned well, spread out toxic gasses and proved fatal in the fire to many people. A prior fire had occurred in the building, also as a result of burning a stage curtain with the spotlights; the curtain

2250-545: The thickness of materials that can be used, but combinations of dampers, barriers, and absorbers are common. Common materials include felt, foam, polyester, and polypropylene blend materials. Waterproofing may be necessary depending on the materials used. Acoustic foam can be applied in different areas of a vehicle during manufacture to reduce cabin noise. Foams also have cost and performance advantages in installation since foam material can expand and fill cavities after application and also prevent leaks and some gases from entering

2300-511: The vehicle. Vehicle soundproofing can reduce wind, engine, road , and tire noise. Vehicle soundproofing can reduce sound inside a vehicle from five to 20 decibels. Surface-damping materials are very effective at reducing structure-borne noise. Passive damping materials have been used since the early 1960s in the aerospace industry. Over the years, advances in material manufacturing and the development of more efficient analytical and experimental tools to characterize complex dynamic behaviors enabled

2350-401: Was acquitted. Families received compensation of up to 50,589 yuan . One week after the fire, city officials in Karamay announced plans to demolish the burned out Friendship Theater. This plan was quickly scrapped following protests by residents of Karamay and parents of the deceased children. Three years later, in September 1997, the theater portion of the building was torn down, leaving only

2400-427: Was built in 1958 following Soviet architecture, renovated starting in 1989 and reentered operation in December 1991. The building had three floors and was originally designed with a capacity of 796 people. The renovation increased it to 810. The soundproofing material was made of asbestos and polyurethane ; the curtains were made of cotton. In certain positions, the spotlight was only at a distance of 20 cm from

2450-399: Was electronically lowered, and the fire was able to be put out. On 8 December 1994, 500 schoolchildren were taken to a special variety performance at a theatre in Karamay at Friendship Theatre ( 友谊馆 ). Most were aged between 7 and 14. At 18:10, a spotlight aimed too close at the curtains overheated the curtains, igniting the curtains towards the rear of the stage. By 18:20, a student in

2500-679: Was officially opened in 2008. A number of natural ( Ailik Lake ) and artificial ( Fengcheng , Huangyangquan) reservoirs are located in Karamay's northeastern Urho District ; they all are replenished, directly or indirectly, by water from the Irtysh–Karamay Canal. Karamay has an extremely continental desert climate ( Köppen climate classification BWk ), typified by great seasonal extremes in temperature, varying by 43.0 °C (77.4 °F); with long, very hot summers (for its latitude) and long, severely cold winters with brief spring and autumn in between. The monthly 24-hour average temperature

#142857