392results about How to "Low infrastructure cost" patented technology

The invention provides a sensor for monitoring an environmental parameter in concrete including an enclosure; a detecting device connected to the enclosure for a detecting at least one environmental parameter in concrete, wherein the detecting device includes at least one capacitive element; an active material connected to the enclosure, wherein the active material is liable to respond to the environmental parameter and is operably connected to the capacitive element; a RFID chip mounted within the enclosure and operably connected to the detecting device; and an antenna operably connected to the RFID chip and the detecting device, wherein the antenna is part of an L-R-C circuit whose resonance frequency shifts within an assigned frequency band. The invention also provides a MEMS-based capacitive element that responds to an environmental parameter in concrete. The invention further provides a method of forming a MEMS-based capacitive element.

A method and apparatus are described including determining a number of clips to be streamed, requesting a selection of a mesh cache server to meet quality of service requirements for streaming the determined number of clips, establishing a streaming route responsive to the mesh cache server selection, receiving the number of streamed clips from the selected mesh cache server if the request is granted, joining a peer-to-peer network, downloading a next clip via the peer-to-peer network, requesting a selection of a mesh cache server to meet quality of service requirements for complimentary streaming any data missing from the next clip, receiving any data missing from the next clip via complimentary streaming if the request for complimentary streaming is granted and continuing to download any missing data of the next clip that has at least one of not passed its playback deadline and not been requested via complimentary streaming.

A method and apparatus are described including receiving a route request message to establish a streaming route, determining a cost of a reverse route and traffic load introduced by the requested streaming route, discarding the route request message if one of wireless interference constraints for the requested streaming route cannot be satisfied and quality of service requirements for the requested streaming route cannot be satisfied, pre-admitting the route request message if wireless interference constraints for the requested streaming route can be satisfied and if quality of service requirements for the requested streaming route can be satisfied, adding a routing table entry responsive to the pre-admission, admitting the requested streaming route, updating the routing table and transmitting a route reply message to an originator if requested content is cached, updating the route request message and forwarding the updated route request message if the requested content is not cached, receiving a route reply message and deleting the pre-admitted routing table entry if a time has expired.

The invention provides a sensor for monitoring an environmental parameter in concrete comprising an enclosure for embedding in concrete; a detecting means connected to the enclosure for detecting at least one environmental parameter in concrete, the detecting means comprising at least one capacitive element for measuring capacitive change; an active material connected to the enclosure, the active material being liable to respond to the environmental parameter and the active material being operably connected to the capacitive element; a RFID chip mounted within the enclosure, the RFID chip being operably connected to the detecting means; and an antenna operably connected to the RFID chip, the antenna being operably connected to the detecting means, and the antenna being part of an L-R-C circuit whose resonance frequency shifts within an assigned frequency band. The invention also provides a MEMS-based capacitor that responds to an environmental parameter in concrete.

The invention relates to a desulfurization waste water recycling and zero discharge system and method. The desulfurization waste water recycling and zero discharge system comprises a desulfurization tower, a filter and a nanofiltration device which are sequentially connected, wherein a scale inhibitor dosing device is arranged at the inlet of the nanofiltration device, the concentrated water outlet of the nanofiltration device is connected with the desulfurization tower, the fresh water outlet of the nanofiltration device is connected with a saline water concentrating device, the fresh water outlet of the saline water concentrating device is connected with a fresh water tank, the concentrated water outlet of the salt water concentrating device is connected with a crystallizer, and the condensed water outlet of the crystallizer is connected with the fresh water tank; a drying encapsulating machine is arranged at the solid outlet of the crystallizer. The desulfurization waste water recycling and zero discharge system has the advantages that desulfurization waste water discharged from the desulfurization tower is filtered and then is fed into the nanofiltration device, nanofiltration concentrated water returns to the desulfurization tower, nanofiltration fresh water is treated by virtue of the salt water concentrating device and then is crystallized by virtue of the crystallizer, the obtained fresh water is recycled in the fresh water tank, and salt is separated out, dried into crystallized salt and transported outside after being encapsulated, so that zero discharge of the desulfurization waste water is realized, quality of the recycled fresh water is improved, and a chemical agent and operating cost are saved.

A method of repairing mine ecological environment comprises the treatment of mine environment contamination, wherein the tailings, the barren rock, the smelting slag, the waste water from ore cleaning, the waste water from smelting, the acid mine drainage and the ore yard leachwater which are generated from mine development are collected into the tailings storage, at the same time, sludge and organic matter capable of being degradated by microbiology are added therein, and then the tailings storage is given an anaerobic environment artificially, so that, under the action of microbiology and sulfate reducing bacteria, sulfur ion is generated and the pH value of the tailings storage is increased, a plurality of heavy metal ions are cured and settled by sulfur ion to avoid migration, a biomembrane layer-sulfate reducing bacteria reducing-induction biomineralization precipitation composite geochemical barrier is generated in the tailings storage. The repairing of mine ecological environment is realized by the treatment of mine environment contamination. The present invention can be used for tailings storage pollution prevention in tour, and can be used for closing the repairing of mine ecological environment, or can be used for designing new tailings storage by using the technology of the present invention.

The present invention is efficient ecological waste water treating apparatus and method. The apparatus consists of grit contacting oxidizing area, vertical upstream flow artificial wet land area, aerating jet area and horizontal flow artificial wet land area connected serially. The present invention has the advantages of composite medium in new recipe resulting in excellent phosphate and organic matter eliminating effect, the grit contacting oxidizing resulting in the long term stable running of the system, the composite of vertical upstream flow artificial wet land and horizontal flow artificial wet land resulting in raised effective volume and the aerating jet creating condition for aerobic degrading of organic matter.

A low-profile, right angle connector assembly comprises six cable connectors and six board-mount connectors housed within a PCIe bracket and EMI shell. The PCIe bracket and EMI shell are braced to a low profile PCIe card. Each board-mount connector is designed to receive a cable connector and allows for the transmission and processing of high-speed data with lower latency. A removable latch mounted on the cable connectors helps ensure the cable connectors remain physically connected to the board-mount connectors. The removable latch may be replaced as needed for breakage and wear and tear.

The invention relates to a technical sphere of sewage disposal with biology suspended carriers. The invention said integrated biology treatment technology of sewage suspended carriers, comprises the following steps: a, reinforcing flocculating sediment: leading domestic sewage or industrial waste water and sequence stage flow-back miscible liquids into reinforced flocculating sedimentation basin, adding flocculant and mixing them, discharging the sediment from the bottom of settling zone; b, biotreatment and solid-liquid separation of an integral suspended carrier bioreactor: dividing a suspended carrier biology reaction pond with perforated boards or block walls into an anoxic zone, an aerobic zone, a solid-liquid separation zone, adding suspended carriers biology filler into each zone to get the integral suspended carrier bioreactor; making supernate obtained from step a flow into said three zones in turn, discharging sediment sludge from the bottom of the solid-liquid separation zone, the clear water discharger from the upper meeting emission standard. The process saves accommodation area, improves trash-removal effet, and it is suitable to different sewage disposal scale and inflow water quality.

The invention relates to an integrated sewage treatment device with high efficiency and low consumption and a treatment method, and belongs to the field of sewage treatment. The integrated sewage treatment device comprises a pretreatment unit, a multi-oxidation-deoxidation environment coupling biological reaction pond unit and a deep treatment unit sequentially connected. The multi-oxidation-deoxidation environment coupling biological reaction pond unit adopts a three-stage anoxia-aerobiotic alternating reaction pond filled with a circular composite glass ball porous microbial carrier. The deep treatment unit comprises a filter cloth dynamic film biological reaction pond and first and second dynamic films. Sewage is treated through the devices sequentially. The device provided by the invention cannot only remove carbon containing organic matters, but also has good nitrogen and phosphorus removal capacity.

A method and apparatus are described including receiving content from a base station, storing the received content, receiving a second message from a first member of a network, determining a highest expected layer, a lowest layer received by the first member of the network requesting help, a highest layer that needs to be multicast to the first member of the network, and a lowest layer that needs to be multicast to the first member of the network, retrieving the stored content responsive to the message and multicasting the retrieved content to the first member of the network responsive to the determining act.

The invention relates to a device and method for treating low-carbon domestic sewage through single-stage SBBR short-range synchronous nitration, denitration and dephosphorization coupled anaerobic ammonia oxidation and belongs to the field of biological sewage treatment. The domestic sewage enters a short-range synchronous nitration, denitration and dephosphorization coupled anaerobic ammonia oxidation reactor through a water feed pump. In the short-range synchronous nitration, denitration and dephosphorization coupled anaerobic ammonia oxidation reactor, phosphorus accumulating bacteria achieve anaerobic phosphorus release by making full use of an organic carbon source in raw water; part of NH4<+>-N in the raw water is converted into NO2<->-N by ammonia oxidizing bacteria, one part of the NO2<->-N and the NH4<+>-N remaining in the raw water are subjected to an anaerobic ammonia oxidation action so as to achieve autotrophic denitrification, and the other part of NO2<->-N and a small amount of NO3<->-N resulting from the anaerobic ammonia oxidation action are utilized by denitration phosphorus accumulating bacteria so as to achieve synchronous deep denitrification and dephosphorization. According to the method, short-range nitration, anaerobic ammonia oxidation and denitration dephosphorization are applied to the biological treatment on the domestic sewage in a coupled manner, so that the synchronous deep denitrification and dephosphorization of the domestic sewage can be achieved on the basis of saving energy and making full use of the carbon source.

A Multimedia Telecommunications Call Center provides integrated video, audio, data and telephony functionality, together with connectivity to the Internet, ISCN, PSTN, and other wide-area networks. The Call Center includes a Local Area Network having a Gateway and a Gatekeeper. Incoming multimedia calls are received by the Gateway and are permitted onto the network under control of the Gateway and are permitted onto the network under control of the Gatekeeper. Communications between the Gateway and the Gatekeeper preferably take place across the network and comply with the ITU H.323 standard protocol. Communications between the Gatekeeper and the Call Manager preferably take place across the network and comply with the European Computer Manufacturers Association CSTA standard protocol.

Under the surface plants several percolating channels and water-distributing grooves are set, the interior of percolating channel is filled with artifically-made speciall soil, and at two sides of water-distributing groove the reinforced water-distributing material can be set, under the action of comprhensive cleaning function of soil, microorganism and plant system, the sewage can be cleaned, the cleaned water can be collected by a water-collecting channel set on the impervious layer of its bottom portion, and discharged out by a water-collecting tube. Said invention can make removing rate of COD, amino nitrogen, total nitrogen and total phosphorus being in domestic sewage by up to above 90%.

The invention relates to a bioaugmentation treatment technology of the high ammonia nitrogen wastewater. The treatment technology is characterized in that under the condition that dissolved oxygen exists in the high ammonia nitrogen wastewater, an aerobic pool, an aerobic filter and a membrane pool are established, wherein by utilizing the metabolism of the aerobic microorganism, high concentration of organic substances are degraded, the organic substances with high molecular weight and energy are converted to substances with low molecular weight and energy; the aerobic pool adopts internal circulation and large-scale external circulation hydraulic agitation; and the aerobic filter is filled with novel fixed enzyme-floating filler and immobilized microorganism and microporous aeration and jet aeration are combined for aeration, thus the flow pattern of the nitrification filter is improved. Compared with the prior art, the system of the invention has high sludge concentration and the corresponding volume loading is also high, thus the floor space is small and the capital cost is low; the conversion rate and utilization rate of atmospheric oxygen is high, the effect of mass transfer is good, the anti-shock loading capability of the system is high, the effluent quality is stable; the operating cost is low; the density is increased relatively, the solid-liquid separating effect is good and the yield of excess sludge is low.

The invention discloses a treatment method of secondary wastewater of kitchen waste. The treatment method comprises the following steps of: (1) carrying out materialization pretreatment on kitchen wastewater to remove floater, animal or vegetable butter, oil and SS (suspended matter) in the wastewater; (2) carrying out the two-stage hydrolysis acidification-IC (internal circulation) anaerobic reaction treatment and biochemical treatment of an aerobiont separation bed on the wastewater; and (3) carrying out flocculation and precipitation on the biochemically-treated wastewater to discharge, and concentrating, dewatering and drying precipitate. The wastewater discharged by using the method reaches The people's Republic of China national standard of sewage comprehensive discharge standard (third-level discharge standard); through two-stage hydrolysis acidification-IC anaerobic reaction treatment, the gross removing rate of CODcr (chemical oxygen demand) can reach more than 92%, and carbon source does not needed to be supplied in the midway of the reaction, so that the normal running of equipment can be guaranteed.

The invention discloses a biological response system for multistage sewage treatment as well as a manufacturing method and a sewage treatment method. The biological response system is formed by connecting a multistage precipitation pretreatment unit, a multistage hydrolysis and acidizing treatment unit, an aeration oxygenation treatment unit and a multistage undercurrent wetland treatment unit through pipelines; the multistage undercurrent wetland treatment unit comprises a water inlet wetland pool, two groups of decomposition and percolation wetland pools and a water outlet wetland pool which are sequentially arrayed; and the multistage precipitation pretreatment unit, the multistage hydrolysis and acidizing treatment unit and the aeration oxygenation treatment unit are sequentially arranged on one side of the multistage undercurrent wetland treatment unit in parallel and are connected with one another through pipelines. The biological response system provided by the invention has the advantages of scientific design, reasonable structure, fewer electromechanical devices due to the adoption of an automatic flow mode, low operation cost, low sewage treatment expense, small floor area, obvious sewage treatment effect, convenience for operation and maintenance management, low cost on project capital construction and operation, and capability of carrying out purification treatment all the year round, ; the treated sewage can be directly discharged into reservoirs, rivers and lakes and is in accordance with discharge standards in China; and a bioecological technology has stronger self-regulation capability and repair capability.

The invention discloses a construction method for an ecological filtration bank used for purifying agricultural runoff pollution. According to the construction method, a novel filtration bank is constructed in an area which is located between farmland and a river and is 15 to 20 meters away from the river; i.e., herbaceous plants and shrubs with well-developed roots, great amount of growth and good absorption effects on nitrogen and phosphorus are planted in the selected area; meanwhile, water distribution ditches and water distribution grooves are arranged at the front end of the selected area, a percolating filter is constructed at the rear end of the selected area, and water collecting pipes are laid at the bottom of the percolating filter. Agricultural runoff water can be introduced to the water distribution ditches and the water distribution grooves through drainage ditches of the farmland and other naturally-formed drainage ditches at first, then is adsorbed, intercepted and absorbed by the herbaceous plants and the shrubs on the filtration bank, undergoes multilayer percolation and purification under the action of different filling materials in the percolating filter and is finally discharged into the river. The filtration bank provided by the invention has the advantages of low cost for capital construction, no need for maintenance and a better purifying effect on total phosphorus, total nitrogen, nitrate and ammonia-nitrogen in agricultural runoff pollution compared with purifying effects of traditional vegetation buffer strands; moreover, the plants planted on the ecological filtration bank exert beautifying and ornamental effects.

The invention pertains to the waste water processing technical field and relates to an oily waste water processing method and complete set of equipment thereof, which is characterized in that: firstly, the waste water is processed by an express pump and then transmitted to a steady flow cylinder by a distributor so as to be treated with demulsification and perikinetic flocculation; afterward, the waste water is transmitted to a mixing tank so as to be treated with orthokinetic flocculation; after being further charged by a high-pressure dissolved air releaser, oil-water separation is carried out to the waste water; and finally, clean water meeting the requirement of environmental protection can be obtained after the waste water is separated in an inclined tube settling zone. The processing method is characterized by simple process and equipment, low investment and low running cost.

This invention discloses a method for producing rise-fall artificial plant floating bed for wastewater biological treatment. The main body of the floating bed is hollow and sealed, and a planting groove is set on the main body. Filler and plants are placed in the planting groove. A support is set in the planting groove, which is connected with water body. Bed connectors are placed surrounding the main body of the floating bed. At least two main bodies are combined to form the floating bed, which is placed on the water surface. The roots of the plants on the floating bed can realize filtration, absorption and adsorption of pollutive substances in wastewater. The floating bed is sinked into the non-frozen layer below water surface in winter, and taken out of water surface inspring. The plants are left for further filtration, absorption and adsorption of pollutive substances in wastewater. This invention has such advantages as short project period, and rapid acting. Plants of the floating bed have a survival period of more than 8 months / year. The planting can match city landscape, thus are good for city afforestation, and can reduce secondary assembly cost. The floating bed just needs replanting in spring.

The invention relates to a system and a method for removing phosphorus by three-mud process nitrification and denitrification. The system comprises a pretreating unit, an anaerobic unit, a middle precipitation unit, a primary aeration biological nitrification unit, an anoxic unit, a secondary precipitation unit and a secondary aeration biological nitrification unit. The method comprises the following steps that: after being precipitated in the pretreating unit for removing oil, the primary water enters an anaerobic pool with returned sludge to anaerobicly release the phosphorus; microorganisms absorb polyhydroxyrate (PHB) in a dissoluble organic compound body in the water; after muddy water is precipitated in a middle precipitation pool, a supernatant enters the primary aeration biological nitrification unit and an effluent and sludge in the middle precipitation pool enter an anaerobic pool to undergo denitrification and dephosphorization; and after mixed solution in the anaerobic pool is separated in a secondary precipitation pool, the supernatant enters the secondary aeration biological nitrification unit for further treatment, wherein one part of the sludge is reclaimed and theother parts of the sludge are discharged as remaining sludge. The system of the invention is small in occupied area and low in basic construction and operation costs. For low-carbon and nitrogen urban sewage, the effluent of the system can stably meet the first grade A standards of Urban Sewage Disposal Plant Contamination Integrated Discharge Standard.

The invention relates to a method for extracting natural products, in particular to a method for extracting eucommia gum from eucommia leaves by using a biological method. The following process steps are included: the first step is pretreatment of eucommia leaves, including pulping and enzymatic hydrolysis. The second step is the preparation of the nitrogen source, including membrane filtration, membrane concentration and resin adsorption, and drying the membrane filtration concentrate and the subcolumn liquid as the nitrogen source for later use. The third step: extraction of eucommia gum, including inoculation of Eucommia ulmoides-16 for solid-state fermentation, separation of solid and liquid from the fermentation product, drying of the liquid as a carbon source for future use, and light washing and refining of the crude gum to obtain fine gum. This method has high production efficiency, low production cost, and can co-produce chlorogenic acid to increase income.

The present invention discloses an air-conditioning unit for machine room, which comprises an indoor air-conditioner and a chiller unit. The chiller unit is connected with the indoor air-conditioner. Chiller water of the indoor air-conditioner is provided by the chilled unit which comprises a compressor, a condensing coil, an expansion valve and an evaporator that are sequentially, front and back connected. A centrifugal fan, a static pressure box and an air outlet of the indoor air-conditioner are sequentially connected. The air outlet is positioned under the indoor air-conditioner. An air return vent is positioned at top of the machine room. The chilled unit also comprises a heat exchanging disc of natural cooling and a tee regulating valve. One end of the heat exchanging disc of natural cooling is connected with a water return pipe of the chiller water of the air conditioning system, and the other end is sequentially connected with the tee regulating valve and an evaporator. The other end of the tee regulating valve is connected with a water return bypass pipe of the air conditioning system. The present invention can optimize the air flow and the distribution of the temperature inside the machine room so as to achieve the best effect of the heat exchanging, and saves the energy by the improvement of the difference between the air supplying temperature and the air returning temperature, and greatly improves the effect of energy-saving by adopting the technical proposal of natural cooling.

The invention relates to a technology of treating coking wastewater by biomembrance process, belongs to the field of environmental protection and difficult degradable industrial wastewater treatment, is mainly used to treat coking wastewater, can also be used to treat high COD and high ammonia nitrogen industrial wastewater and can realize that COD can be removed effectively and denitrification can be carried out effectively. The reactors used by the invention comprise an anaerobic bacteria filter, an aerobic biological fluidized bed, an anoxic biofilter and a settling pond. The technology is that the pretreated coking wastewater flows through the anaerobic bacteria filter for hydrolysis acidification, the aerobic biological fluidized bed for oxidation, then the anoxic biofilter for filtration, the settling pond for removing suspended matter and the treated water generated in the settling pond is directly discharged and part of the treated water flows back to the anaerobic bacteria filter. The COD removal rate of effluent can be above 95%, and the other indexes can all reach the primary standard of the national standard (GB8978-1996) for effluent discharge. The treatment technology has higher hydraulic loading and resistance shocking and lower floor area.

The invention belongs to the technical field of sewage processing, and concretely relates to an integrated electrochemical reaction apparatus for processing difficultly degraded organic waste water and a processing method thereof. A housing of a reactor is divided into a circle cavity reaction zone and a cone cavity precipitation zone, a semi-arc ruthenium iridium anode and a semi-arc porous iron net are arranged in the circle cavity reaction zone, the insulation pads which are symmetrically distributed are arranged at the intermediate part, and a stainless steel cathode is arranged in the housing of the reactor; a discharge pipeline is arranged at the bottom of the cone cavity precipitation zone, an water inlet pipe is arranged at the top of the housing of the reactor, a drainpipe is arranged at the bottom of the housing of the reactor; and the semi-arc ruthenium iridium anode, the semi-arc porous iron net and the stainless steel cathode are connected with stabilized power supply. Waste water is introduced into the reactor through the water inlet pipe, the reactor is turned on, the stabilized power supply and a motor are turned on, the cathode is rotated with the motor slowly, the waste water is stirred slowly with the cathode, the waste water is subjected to Fenton-like and electric flocculation reactions near the porous iron net, electrooxidation is generated near the ruthenium iridium anode, the waste water is discharged from the drainpipe, and a precipitate is discharged through the discharge pipeline.

The invention discloses nonferrous mine mullock concrete used as filling and the preparation method thereof, and relates to the concrete which is used for mining backfilling and the preparation method thereof. The preparation method includes the following steps: at first, the mullock is crushed into grains with the diameter being 5 to 30 mm, then the mullock, ore dressing milltailings and fly ashes are adopted to be used as aggregate according to the weight rate of (5 to 7):(4 to 6):(0 to 3), and cement is adopted according to the weight rate (7 to 11): 1 part of the cement, then admixture is adopted with the weight of 0.3 to 1.5 percent of the cement. Then the aggregate, the cement, the admixture and mining wastewater are put into an agitator to agitate and make mortar with 65 to 88 percent of weight percentage concentration, then the mortar is cast and molded to be mullock concrete on the spot, or a mortar pump is sent to the site of the backfill mine, then cast and moulded to be the mullock concrete. Through detecting, the mullock concrete satisfies the strength requirement that R3 is equal to or larger than 1.5 MPa, R7 is equal to or larger than 2.5 MPa, R28 is equal to or larger than 5.0 MPa, the slump is equal to or larger than 22 cm, and the horizontal distance is equal to or larger than 500 m, and the height is equal to or larger than 30 m. The invention has the advantages of saving material by 10 to 20 percent, recycling the mullock and reducing the mine construction cost, thereby having obvious economic and environmental benefits.

The invention discloses a power plant desulfurization waste water membrane concentrating process. The process comprises the step that water quantity and water quality of desulfurization waste water are adjusted in an adjusting tank, and the adjusted desulfurization waste water is reacted with lime in a first reaction tank, enters a second reaction tank in a coagulation fluid state to be reacted with sodium carbonate and then enters a concentrating water tank in a coagulation fluid state; waste water in the concentrating water tank is lifted to a UF membrane component, filtered contributing water enters a neutralizing tank, the pH value of the contributing water is adjusted through industrial hydrochloric acid, and concentrated water flows back to the concentrating water tank; ultra-filtered contributing water with the pH value adjusted in the neutralizing tank is pumped to a first-stage RO membrane component to be concentrated through a pump, obtained concentrated water is pumped into a second-stage RO membrane component through a pump, concentrated water enters an evaporator, the contributing water of the second-stage RO membrane component flows back to the first-stage RO membrane component to be treated, and the contributing water of the first-stage RO membrane component and evaporator condensate water are recycled for slurry mixing of production process agents. The invention discloses power plant desulfurization waste water membrane concentrating equipment. By means of the power plant desulfurization waste water membrane concentrating process and equipment, the concentrating effect of the desulfurization waste can be improved, the chemical agent and operating cost can be reduced, and the zero-release requirement can be met.

The invention provides a comprehensive treatment method for acid mine water of small abandoned coal mines. A slurry is injected into a grouting filling layer, a plugging surface layer is formed afterthe slurry is solidified, the underground water supplementary amount of atmospheric precipitation to underground mined-out areas of the abandoned mines in a target area is reduced, and a permeable reactive barrier, a continuous alkali production pool and a constructed wetland section are continuously arranged at mine wellheads of the small abandoned coal mines with relatively good maintenance conditions; a drainage canal collection system is built around surface rivers in the target area; coal gangue piles in the target area are subjected to closed treatment. The integrated technical scheme realizes comprehensive treatment of the acid mine water in a number of small abandoned coal mines distributed in the target area, and has the advantages of high practicability, low cost and good effect.