46results about How to "Good adjustment stability" patented technology

The present invention relates to a temperature control device of an automatic injection plastic hollow molding machine. The device consists of a PLC-high-speed singlechip system, a temperature sensor signal amplification circuit, a heating device drive circuit and an operation panel; the method is that temperature information is converted into electricity information through temperature sensor; temperature signal is exerted into an operational amplifier through a bridge detecting circuit of the temperature sensor signal amplification circuit and a lowpass; after amplification, the temperature signals are converted into digital signals through a A / D converter of the high-speed singlechip, and then difference value is achieved after comparison with a temperature setting control value, and then a control value is achieved through fuzzy PID calculation; the control value is converted into square waves with certain dutyfactor; heating power of a solid-state relay for driving heated circle is output and controlled by an I / O port of the high-speed singlechip; a dynamic value and a setting control value of eight-way temperature are displayed in a dot matrix LCD module of the operational panel in real-time. The device and the method are exact in temperature control effect, high in performance-price ratio, simple in operation.

The invention discloses to an infant paper diaper with excellent antibacterial performance. The infant paper diaper with excellent antibacterial performance comprises a paper diaper body, wherein thepaper diaper body comprises a liquid permeable layer, a guide layer, a coating layer and a liquid impermeable bottom film layer which are sequentially compounded from top to bottom, the coating layeris coated with an absorbent core body, the absorbent core body is sequentially provided with an upper absorbent layer, an absorbent core material and a lower absorption layer from top to bottom, wherein the absorbent core material comprises a high-molecular water-absorbing resin, a chitosan buffer solution and a fluff pulp, the weight ratio of the high-molecular water-absorbing resin, the chitosanbuffer solution and the fluff pulp is 6-15:0.5-2:15-25. The paper diaper with excellent antibacterial performance solves the problem that the paper diaper has no antibacterial effect or safety uncertainty of the silver-containing antibacterial agent in the prior art, can maintain the pH environment of the paper diaper, and reduces the stimulation of the diaper on the skin.

The invention relates to an underwater verticality adjustment device of an acoustic Doppler current profile (ADCP) sensor, and belongs to the field of hydrologic monitoring. A worm and gear speed changing box is fixedly arranged on a fixed framework which is fixed on a prefabricated foundation, a sleeve of a rocker arm mechanism is in clearance fit with a worm-wheel shaft of the worm and gear speed changing box, a cross axle adjustment mechanism is installed on the fixed framework, the ADCP sensor is arranged on the cross axle adjustment mechanism and is fixedly connected with a linear bearing and a guide rod mechanism of the linear bearing, one end of a transmission mechanism 7 abuts against the sleeve of the rocker arm mechanism, the other end of the transmission mechanism is connected with the linear bearing and the guide rod mechanism of the linear bearing, and the worm and gear speed changing box and the rocker arm mechanism are provided with tensioning mechanisms. The device has the advantages of being small in size, light in weight, precise in positioning, and convenient to install, adjust and maintain, and the like; adjustment stability in the horizontal direction and the vertical direction is good; and compared with the prior art, the device is precise in positioning, can guarantee completeness and reliability of hydrologic data collection, has a self-lock function, and is simple and novel in structure, convenient to use, and strong in practicability.

The invention provides a reinforcing steel formwork supporting rack for a thin-walled hollow high pier and a construction method. The reinforcing steel formwork supporting rack comprises a reinforcing steel formwork supporting framework and an operation platform, wherein the reinforcing steel formwork supporting framework comprises vertical columns, a transverse bridge direction cross rod and a longitudinal bridge direction cross rod, wheel discs are arranged at the bottom ends of the vertical columns, the bottom ends of the vertical columns are in welded connection with the wheel discs, the wheel discs are fixedly connected with rollover purlins of set-shaped steel formworks through bolts, connecting steel plates are welded at the top ends of the vertical columns and connected with the longitudinal bridge direction cross rod at the top through bolts, and the transverse bridge direction cross rod is perpendicular to the longitudinal bridge direction cross rod, erected on the top surface of the longitudinal bridge direction cross rod and connected with the longitudinal bridge direction cross rod though the bolts; and operation platform comprises triangular reinforcing steel brackets and operation platform stirrups, vertical supports of the triangular reinforcing steel brackets are attached to the tops of the outer walls of the vertical rods and are in welded connection, the operation platform stirrups are uniformly distributed, and the end parts are undertook transversely on the triangular reinforcing steel brackets. The reinforcing steel formwork supporting rack for the thin-walled hollow high pier and the construction method have the advantages that thickness of a protective layer is easy to control, safety and reliability are achieved, construction cost is saved and the like.

The invention relates to a variable parameter control method for a hydro governor of a variable-crown elevation tailrace tunnel. According to field tests of different water heads and different downstream water levels, optimal PID control parameters of the hydro governor at different water head sections and different downstream water level sections are determined through simulating calculation, and finally a parameter list is obtained. A working head of a water turbine and signals of downstream water levels are introduced to the hydro governor, the hydro governor automatically selects the PID parameters in the parameter list according to the real-time working head of the water turbine and the real-time downstream water levels, and therefore a regulating system of the water turbine of the variable-crown elevation tailrace tunnel can meet the stability requirement and has high regulation quality.

The invention relates to a radar communication antenna capable of accurately adjusting signal receiving height and orientation, comprising a base, a base frame is welded on the base, and a base cover is welded on the top of the base frame; the base frame is provided with a guide groove in a spiral structure, the base frame The outer wall is equipped with a support sheet in a spiral structure, and a guide chute in a spiral structure is arranged on the support sheet; a ring-shaped guide mechanism is installed at the lower end of the base cover, and a rotating gear is installed at the lower end of the ring-shaped guide mechanism. The left and right sides of the rotating gear Both ends are meshed with a driving mechanism; a sliding mechanism is installed in the guide chute, and an antenna mechanism is installed on the sliding mechanism; a winding mechanism is installed on the lower surface of the rotating gear, and the driving mechanism, rotating gear, ring guide mechanism, The mechanism, the sliding mechanism and the antenna mechanism cooperate to move to complete the spiral lifting and guiding process of the antenna mechanism. The invention can realize the functions of stable automatic spiral lifting signal height of radar antenna and precise adjustment of signal receiving azimuth.

The invention discloses a helical blade rolling mill which comprises a stand, and two ends of the stand are symmetrically arranged; a fixed shaft is horizontally arranged along two ends of the stand, a support seat is symmetrically hinged at the approximately middle part of the fixed shaft, an angle adjusting device is arranged at the lower end of the support seat, and axial moving devices are symmetrically arranged along two sides of the support seat; a sliding seat which can slide up and down along the support seat is arranged at the outer side of the support seat, a main shaft driven by a power driving mechanism is arranged in the sliding seat, and tapered rollers are arranged at the upper end of the main shaft; and feeding devices and discharging devices are oppositely arranged at two sides of the tapered rollers. In the invention, as two rollers are supported on the same fixed shaft by the support seat, the central axial lines of the two rollers can be ensured to be coplanar as long as two sliding seat mounting holes on the support seat are ensured to be coaxial; as the helical blade rolling mill adopts the structure, the two sliding seat mounting holes are very easy to be coaxial, and the central axial lines of the two rollers have simple planar structure and are convenient for aligning; and the support seat is hinged on the fixed shaft, thereby having good adjusting stability.

The invention discloses a rotatably adjustable Beidou satellite high-dynamic anti-interference antenna, which comprises a shell, a base is welded at the lower end of the shell, a bottom plate is rotatably connected in the base, two cushion blocks are arranged in the shell and are symmetrically distributed in the shell, elements are fixedly mounted on the cushion blocks, a shell cover is connected to the shell through screws, a support is fixedly sleeved with the shell cover, a blocking cover is connected to the support through threads, a rotating base is arranged in the blocking cover, the blocking cover is in contact connection with the outer side of the rotating base, the support is in contact connection with the outer side of the rotating base, and an opening groove is formed in the rotating base. A sliding groove is formed in the blocking cover, and the rotating base is connected into the sliding groove in a sliding mode. The invention relates to the rotatably adjustable Beidou satellite high-dynamic anti-interference antenna. The rotatably adjustable Beidou satellite high-dynamic anti-interference antenna has the advantages that the device adjusting stability is good, and the antenna can be rotationally adjusted in all directions.

Fabrication method for a semiconductor memory device and structure are provided, which includes: providing at least two mask layers over a pair of fin structures extended above a substrate, wherein a first mask layer of the at least two mask layers is orthogonal to a second mask layer of the at least two mask layers; and patterning the pair of fin structures to define a pass-gate transistor, wherein the first mask layer facilitates removing of a portion of a first fin structure of the pair of fin structures to define a first pass-gate fin portion of the pass-gate transistor, and the second mask layer protects a second fin structure of the pair of fin structures to define a second pass-gate fin portion of the pass-gate transistor.

The invention discloses a material shaft of a coiling machine. The material shaft comprises a material shaft body. The material shaft is characterized in that a three-jaw expansion mechanism and a material shaft axial position adjusting mechanism are arranged on the material shaft body, wherein the material shaft is fixedly connected with a coiling machine tool through a rear base on the material shaft axial position adjusting mechanism. According to the material shaft in the structure, materials are fixed by adopting the three-jaw expansion mechanism, the materials of different widths are automatically centered, the coaxiality of the materials with the material shaft is greatly increased, and wrinkles of electric capacitor elements in the coiling process are effectively reduced; the mode of fixing the materials by the three-jaw expansion mechanism is applicable to the materials with various widths, the structure is reasonable and compact, the materials are conveniently disassembled and assembled, the working intensity of operators is reduced, the production efficiency is improved, and the materials are good in axial position adjustment stability, so that the material shaft is applicable to a conventional tension mechanism, can be still used for carrying out the adjustment on the axial position of the materials, and is good in axial position adjustment stability, and the adjustment operation mode of the tension and the axial positions of the materials are not changed.

The invention discloses a faucet which comprises a shell. An assembling opening is communicated to a flowing channel between a water inlet connecting pipe opening and a water outlet, the assembling opening is provided with a control mechanism used for adjusting and controlling the flow of water flowing from the water inlet connecting pipe opening to the water outlet, the control mechanism comprises a fixed sheet, a movable sheet, a fastening piece and a valve rod, wherein the fixed sheet is arranged at the bottom end of an inner cavity of the assembling opening, covers the flowing channel between the water inlet connecting pipe opening and the water outlet and is used for forming a fixed flowing channel, the movable sheet presses and covers the fixed sheet in a face attachment sealing manner, is used for forming a movable flowing channel and is in rotary fit with the fixed flowing channel on the fixed sheet to form flowing channels in different radial size for controlling the water flow, the fastening piece presses and covers the movable sheet in a face attachment sealing manner,, is used for sealing the assembling opening, and is used for fixing and positioning the movable sheetand the fixed sheet in the axial direction, and the valve rod is located in a cavity defined by the fastening piece and the movable sheet, is connected with the movable sheet, and is used for controlling rotation adjustment of the movable sheet and limiting radial movement of the movable sheet; and the outwards-extending end of the valve rod is provided with a driving mechanism used for driving the valve rod to rotate.

The invention discloses an efficient heat supply system arranged in a secondary reheating unit. The efficient heat supply system comprises a small steam turbine, a clutch gear box, a motor / generator and an induced draft fan; a rotating shaft of the small steam turbine is connected with the clutch gear box, one side of the clutch gear box is connected with the small steam turbine, and the other side of the clutch gear box is connected with a rotating shaft of the motor / generator; and the motor / generator is connected with the induced draft fan, the small steam turbine and the clutch gear box arecoaxially connected with the motor / generator and the induced draft fan, the motor / generator is electrically connected with a station service bus, and a steam exhaust port of the small steam turbine is connected with the heat supply steam manifold. According to the efficient heat supply system arranged in the secondary reheating unit, the problem of insufficient reheat steam temperature can be relieved, and the reheat steam temperature regulation stability is facilitated; and meanwhile, heat is supplied to the outside, parameters of heat supply system meet the use requirements of other parts of equipment of a power plant, redundant steam can be directly reused, high-quality steam is extruded to do work, and the utilization rate of heat energy is increased.

The invention relates to the field of college furniture, in particular to an anti-collision head type bed for schools. The bed comprises a bed frame, a bed plate is arranged on the bed frame, the bedplate comprises a fixed plate and a rotating plate, a rotating assembly used for driving the rotating plate to rotate is arranged on the bed frame, and a mattress pressing assembly used for pressing amattress is further arranged on the bed frame; the bed has the effect of reducing the situation that the head of a user touches the bed edge.

The invention relates to a lightweight explosion-proof security and protection monitoring camera. The lightweight explosion-proof security and protection monitoring camera comprises a camera and a mounting shell, wherein the front side of the lower surface of the camera is in universal rotary connection with the inner bottom of the mounting shell through a universal seat; a supporting spring is arranged on the inner bottom surface of the mounting shell; a first elastic air bag, a second elastic air bag and a third elastic air bag are arranged on the upper surface, the left side surface and theright side surface of the tail of the camera respectively; a first micro air pump and a second micro air pump are arranged in the mounting shell; the second elastic air bag and the third elastic airbag are filled with inert gas and communicated through two parallel pipelines, and two third micro air pumps opposite in air exhaust directions are arranged on the two pipelines. By means of the mode,a metal frame for angle adjustment is omitted for the explosion-proof camera, the overall weight is greatly reduced, the adjustment stability is good, the angle can be finely adjusted, the overall structure is simple, the cost is low, the integrity is good, and meanwhile the shock absorption effect is achieved.

The invention discloses a dyeing sludge treatment device which sequentially comprises a settling box, an anaerobic digestion reactor, a dryer, a grinding device and a combustion device according to the sludge treatment process, wherein an electric heating sleeve for heating and drying material is mounted at the outer part of the dryer; a gas outlet is formed on the anaerobic digestion reactor; a discharge pipeline is arranged at the lower parts of the settling box, the anaerobic digestion reactor, the dryer, the grinding device and the combustion device respectively; the discharge pipeline of the settling box is connected with a feed port of the anaerobic digestion reactor; the discharge pipeline of the anaerobic digestion reactor is connected with a feed port of the dryer; the discharge pipeline of the dryer is connected with a feed port of the grinding device; the discharge pipeline of the grinding device is connected with a feed port of the combustion device; and a discharge valve is arranged on each discharge pipeline. The treatment device disclosed by the invention can effectively reduce concentration of harmful substances in sludge and reduce pollution caused after sludge discharge.

The invention discloses a telescopic anchor rod. The telescopic anchor rod comprises a first anchor rod and a second anchor rod which are rotationally connected through threads; a grout stop plug, a pressure bearing gasket and a grouting head are sequentially arranged at the top end of the first anchor rod from bottom to top and fixedly connected through a nut at the top; the bottom end of the second anchor rod is connected with a drill bit; a spiral rod piece, a drive mechanism, a first blocking piece and a second blocking piece are arranged in a cavity of the first anchor rod and a cavity of the second anchor rod; the drive mechanism is arranged between the first anchor rod and the second anchor rod and connected with the first anchor rod and the second anchor rod through the spiral rod piece; the first blocking piece and the second blocking piece are arranged in the first anchor rod and the second anchor rod correspondingly; on the two sides of the drive mechanism, the top end of the spiral rod piece is connected with the pressure bearing gasket, and the bottom end of the spiral rod piece is connected with the second blocking piece; and the drive mechanism is provided with an open hole for containing the spiral rod piece. The telescopic anchor rod is simple in structure, firm, reliable, convenient and fast to operate, adjustable in length, good in adjusting stability, high in tensile strength, wide in application range and low in cost.

The invention relates to a method and system for testing an automobile hybrid power system, and belongs to the technical field of automobile testing. The method comprises the following steps: acquiring monitoring information corresponding to different heat dissipation schemes under the same acceleration starting test condition; calculating the heat dissipation coefficient variation amplitude corresponding to each heat dissipation scheme according to the heat dissipation coefficient information of the automobile heat dissipation system corresponding to each heat dissipation scheme; calculating the confidence coefficient of the heat dissipation coefficient information corresponding to each heat dissipation scheme according to the working condition efficiency coefficient information of the automobile hybrid power system corresponding to different heat dissipation schemes; calculating a reference heat dissipation gain value corresponding to each heat dissipation scheme and a rationality index of the heat dissipation gain coefficient adjustment sequence; taking the reference heat dissipation gain value with the maximum rationality index as the reference heat dissipation gain value corresponding to the target acceleration starting condition; and obtaining a heat dissipation gain coefficient adjustment optimization sequence corresponding to the target acceleration starting condition according to the heat dissipation gain coefficient adjustment reference sequence. The service life of the heat dissipation system is prolonged on the premise that the heat dissipation requirement is met.

The invention provides a pH value control device and method for a chemical combination tank for an EMD continuous leaching process, and relates to the field of industrial automatic control. The pH value control device comprises a PLC control system, an operation panel, four online pH instruments, three electromagnetic valves, a sampling pump and three regulating valves. The set pH control value, the sampling time interval and the control parameter of the chemical combination tank are input through the operation panel, a CPU module of the PLC control system obtains the current real-time pH value of the chemical combination tank through an analog quantity input module, then a control value is obtained through PID calculation and transmitted to the regulating valves through an analog quantity output module, the regulating valves control the opening degrees of the valves according to the control value, the slurrying feed quantity is controlled, and thus stable control over the pH value of the chemical combination tank is achieved. By adoption of the pH value control device and method for the chemical combination tank for the EMD continuous leaching process, online automatic pH value acquisition, actual pH value deviation compensation and pH target value correction can be achieved, and the pH value can be adjusted to the optimal range in the production process.

The invention provides a high-performance alkali-free liquid accelerator. The high-performance alkali-free liquid accelerator is prepared from the following raw materials in parts by weight: 450 partsof aluminum sulfate, 60-80 parts of magnesium sulfate, 5 parts of triethanolamine, 3 parts of sepiolite, 10 parts of diethanolamine and 472 parts of water. The defects of a traditional accelerator are overcome, and the comprehensive use performance of the accelerator is improved.

The invention relates to the technical field of liquid conveying equipment, in particular to a special liquid flow multi-position output control structure. The technical solution adopted by the present invention is: comprising a cylindrical control structure main body, the left side of the control structure main body is provided with an integrally formed engaging connecting column, and the center position of the left end face of the engaging connecting column is provided with a second engaging assembly column, The center position between the second engaging assembly column and the main body of the control structure is provided with a cylindrical first engaging assembly column, and the left center of the second engaging assembly column is provided with a cylindrical main input hole, and the right side of the main input hole is A cylindrical main output hole is provided, and a flow control groove is arranged on the outer cylindrical surface of the main body of the control structure, and first liquid delivery holes and second liquid delivery holes are alternately arranged on the flow control grooves. The invention has the advantages of more convenience in use, better flow regulation stability, more convenient assembly operation, higher assembly efficiency, lower production cost and better effect of controlling liquid flow.

The invention discloses a reflector device for a turning blind area of a traffic curve. The reflector device comprises a base, a supporting frame is arranged on the base, and a positioning ring is arranged at the top of the supporting frame. A reflector is arranged at the position of the positioning ring, a positioning shaft is arranged on the positioning ring, and a coil pipe sleeves the peripheral surface of the positioning shaft and is installed on the back of the reflector. Positioning shells are arranged at one side of the supporting frame, clamping mechanisms are arranged on the positioning shells, and one side of the reflector is clamped in the clamping mechanisms. A supporting mechanism is arranged between the positioning shells and comprises a back frame, a supporting seat is arranged on the back of the reflector, and a magnetic attraction plate is arranged on the front face of the supporting seat and is fixed to the back of the reflector. A positioning pipe is arranged on theinward face of the back frame and sleeves an adjusting shaft, and the end of the adjusting shaft is connected with the back of the supporting base. According to the invention, the reflector can be flexibly adjusted, and the visibility of a curve turning blind area of a municipal road can be greatly improved through the reflector, so that the safety is greatly improved.

The present invention relates to a temperature control device of an automatic injection plastic hollow molding machine. The device consists of a PLC-high-speed singlechip system, a temperature sensor signal amplification circuit, a heating device drive circuit and an operation panel; the method is that temperature information is converted into electricity information through temperature sensor; temperature signal is exerted into an operational amplifier through a bridge detecting circuit of the temperature sensor signal amplification circuit and a lowpass; after amplification, the temperaturesignals are converted into digital signals through a A / D converter of the high-speed singlechip, and then difference value is achieved after comparison with a temperature setting control value, and then a control value is achieved through fuzzy PID calculation; the control value is converted into square waves with certain dutyfactor; heating power of a solid-state relay for driving heated circle is output and controlled by an I / O port of the high-speed singlechip; a dynamic value and a setting control value of eight-way temperature are displayed in a dot matrix LCD module of the operationalpanel in real-time. The device and the method are exact in temperature control effect, high in performance-price ratio, simple in operation.

The invention relates to a variable parameter control method for a hydro governor of a variable-crown elevation tailrace tunnel. According to field tests of different water heads and different downstream water levels, optimal PID control parameters of the hydro governor at different water head sections and different downstream water level sections are determined through simulating calculation, and finally a parameter list is obtained. A working head of a water turbine and signals of downstream water levels are introduced to the hydro governor, the hydro governor automatically selects the PID parameters in the parameter list according to the real-time working head of the water turbine and the real-time downstream water levels, and therefore a regulating system of the water turbine of the variable-crown elevation tailrace tunnel can meet the stability requirement and has high regulation quality.

The invention provides a precise sight adjustment device for an optical alignment telescope, and solves the problems that a conventional precise sight adjustment device for the optical alignment telescope is unreliable in fastening, relatively poor in universality and flexibility, and poorer in stability and accuracy of an optical alignment. The device comprises a supporting bottom plate, a gantryclamping seat mechanism and a flexible fixing mechanism; the gantry clamping base mechanism and the flexible fixing mechanism are arranged on the supporting bottom plate; the front end of a to-be-adjusted optical alignment telescope is coaxially provided with a spherical accessory, and the rear end of the to-be-adjusted optical alignment telescope is coaxially provided with a square accessory; the front end and the rear end of the to-be-adjusted optical alignment telescope are respectively clamped in the flexible fixing mechanism and the gantry clamping seat mechanism; the front end of the flexible fixing mechanism rotates along with the sphere center formed by the spherical cup base of the flexible fixing mechanism and the pressing sphere plate; and the rear end of the gantry clamping seat mechanism performs azimuth and pitching rotation under the matching of a precision adjusting assembly and an elastic top sleeve of the gantry clamping seat mechanism, and is locked under the actionof a locking assembly.

The invention discloses a textile fabric performance testing machine, and belongs to the technical field of textile. The testing machine comprises a rack; a fan is installed on the left side of the upper surface of the rack and used for extracting external air to detect the air permeability of the textile fabric, an air outlet of the fan communicates with an air conveying pipe fixed to the rack through a fixing plate, and the air conveying pipe communicates with a plurality of first communicating hoses. An adjustment mechanism is arranged to cooperate with a testing mechanism, a sealing insertion plate matches a sealing insertion groove to clamp the edge of the cloth into the sealing insertion groove, a pressing mechanism is used to fix the cloth, stable proceeding of testing operation is guaranteed, a plurality of adjusting mechanisms are used with a plurality of partition plates for use, ventilation capacity testing can be conducted on different kinds of cloth at the same time, the position of an adjusting plate can be adjusted, the air volume can be adjusted, different test requirements can be met, the structure is simple, and operation is convenient.

The invention discloses a preparation method of a porous spherical compound humidifying agent, which comprises the following steps of: a, activating zeolite for 2-3h at a temperature of 450 DEG C to obtain activated zeolite; b, adding 30 parts by mass of polyacrylic acid into a sodium hydroxide solution prepared from 15 parts by mass of sodium hydroxide and 100 parts by mass of distilled water so that polyacrylic acid is neutralized, then adding 0.9-2.7 parts by mass of sodium carboxymethylcellulose, 3-6 parts by mass of activated zeolite and 0.3 part by mass of potassium persulfate into a container containing the solution, stirring for reaction at a temperature of 70-80 DEG C; 30min later, dissolving 0.3 part by mass of aluminium chloride in 10 parts by mass of distilled water to obtain a solution, adding the solution in the reactor; adding 0.3 part by mass of N,N-methylenebisacrylamide, continuously stirring for reaction for 0.5-1h till a gel effect happens; and c, adding 0.9 part by mass of sodium bicarbonate into the reactor to generate aluminium hydroxide and carbon dioxide, carrying out primary foaming, stirring for reaction for 0.5-1h to obtain a synthetic product; heating for 1-2h at a temperature of 150 DEG C so that the aluminium hydroxide is decomposed and water is evaporated, and carrying out secondary foaming and drying to obtain the porous spherical compound humidifying agent. The porous spherical compound humidifying agent has the advantages of high humidifying response speed, high moisture content and moisture capacity, good regulation stability, convenience in preparation, low cost, good effect, environmental friendliness and no pollution.