920results about How to "Reduce leak rate" patented technology

A substantially oxygen-free and nitrogen-free plasma ashing process for removing photoresist in the presence of a low k material from a semiconductor substrate includes forming reactive species by exposing a plasma gas composition to an energy source to form plasma. The plasma gas composition is substantially free from oxygen-bearing and nitrogen-bearing gases. The plasma selectively removes the photoresist from the underlying substrate containing low k material by exposing the photoresist to substantially oxygen and nitrogen free reactive species. The process can be used with carbon containing low k dielectric materials.

The present invention discloses an isolating material air permeability measuring device which comprises a double vacuum sealing structure permeating gas sampling device and an isolation material air permeability measuring device of the current limiting air extraction pipeline, the device comprises a permeation gas sampling device with double vacuum sealing structure, an ultrahigh vacuum system, a mass spectrograph and a calibrating device, wherein the permeation gas sampling device is connected to the mass spectrograph 3, the current limiting air extraction pipeline 6 and the calibrating device 19-24 through the flange 2 and the vacuum valve 4. The device can overcome the defects of low signal-to-noise ratio when the mass spectrum signal of the permeation air is measured and difficulty for measuring the isolation material with low air permeability existing in the existing technique, and has the characters of quick measuring speed, being able to measure the permeability rate of all gases to the isolation material.

A method and a system for using RFID (Radio Frequency Identification) in the workflow of a blood center and a medical institution from a network Customer Relationship Management (CRM) information system. The CRM comprises an RFID technique system, a computer database system, and a computer information network. The information transferred between an integrated circuit and a reader-writer occurs through the radio waves in the workflow of, for example, a blood center or other medical institution. The related information ranges from identity information to biological product information. In each procedure of the blood collecting and supply workflow, the information is read / written by the computer into electronic tag and through the computer information network into the service management information system. The work flow of blood centers (stations), such as blood test reports before and after blood transfusions and the desired information of people and objects involved in blood transfusions, can thereby be recorded completely, integrally, precisely, and comprehensively by the RFID system.

The invention relates to a simple, high-efficiency and reliable cold-warm air-conditioning water heater, which comprises a refrigerant loop, a hot-water condensing heat exchanger, a hot-water storing box and a signal acquisition and circuit control system. A scheme I of the invention is characterized in that: an exhaust opening of a compressor is connected with an air inlet of a three-way valve; a first air outlet of the three-way valve is connected with a refrigerant inlet of the hot-water condensing heat exchanger, and a second air outlet is connected and communicated with a first interfaceof a four-way valve and a refrigerant outlet of the hot-water condensing heat exchanger; a second interface, a third interface and a fourth interface of the four-way valve are respectively connected with the upper ports of an outdoor-wind heat exchanger and an indoor-wind heat exchanger and an air inlet of an air-liquid separator, and a capillary is connected in series between the lower ports of the outdoor-wind heat exchanger and the indoor-wind heat exchanger; an air outlet of the air-liquid separator is connected with an air inlet of the compressor; and an electromagnetic guide-valve low-voltage air-outlet pipe of the three-way valve is communicated with an air-sucking pipe of the compressor, and an electromagnetic guide-valve high-voltage air-inlet pipe of the four-way valve is communicated with an exhaust pipe of the compressor. A scheme II of the invention is characterized in that: the hot-water condensing heat exchanger is added between the exhaust opening of the compressor of a refrigerant-circulating loop of a cold and warm air conditioner and an air inlet of the four-way valve, and the electromagnetic guide-valve high-voltage air-inlet pipe of the four-way valve is communicated with the exhaust pipe of the compressor; and the two technical schemes both have four functions of hot-water making and refrigerating, hot-water making, refrigerating and heating.

A feedthrough connector for an implantable medical device includes a hermetically sealed housing containing an electrical circuit and a tubular barrel with an open end and a closed end defining a tubular channel that protrudes into the sealed housing while maintaining the seal of the housing. The inside of the tubular channel is open to the outside of the sealed housing through the open end and the tubular barrel also has a plurality of circumferentially spaced openings extending between an outer peripheral surface and the tubular channel. An electrical contact assembly electrically in common with the electrical circuit within the housing serves to make electrical contact with an electrical lead axially inserted into the open end of the tubular channel. The electrical contact assembly includes a plurality of contact members received in and projecting radially through a plurality of circumferentially spaced openings and a sleeve member of shape memory alloy freely overlies the contact members when in a first deformed-shape configuration but engage the contact members and the outer peripheral surface of the tubular barrel when in a second memory-shaped configuration, urging the contact members into mechanical, electrical, and hermetically sealed engagement with the electrical lead. The tubular channel may include a plurality of conductive cylindrical portions coaxial with the axis of the tubular barrel, the dimensions of the diameter of the successive cylindrical portions progressively decreasing from the open end to the closed end.

The invention relates to a micro electro mechanical system (MEMS) manufacturing process-based micro atomic cavity air tightness package structure and a method. The structure and the method are characterized in that: a micro atomic cavity which is manufactured by the MEMS process is arranged in a glass or metal seal buffer cavity through a supporting structure, and the air tightness of the micro atomic cavity is improved, so that the service life of devices such as a micro atomic clock and the like based on the micro atomic cavity is prolonged, and the stability of the devices is improved. The structure and the method have a key point that: in the glass or metal buffer cavity structure, the inside of the buffer cavity is vacuumized or filled with buffer gas of which the components and the pressure are approximate to those of gas in the micro atomic cavity, and a leading wire of the micro atomic cavity passes through the buffer cavity to realize air tightness lead. By the package structure and the method, the leakage rate of the micro atomic cavity and outside can be effectively reduced, and the technical problem of short service life of micro atomic cavity devices is solved. The air tightness package structure is particularly suitable for the micro atomic cavity devices such as micro atomic clocks, micro atom magnetometers, micro atom gyroscopes and the like with low power consumption and small volumes.

Provided are an exhaust gas treatment catalyst capable of reducing ammonia leakage rate while keeping a sufficient NOx removal efficiency, said catalyst comprising a coating layer and a catalyst base material, wherein said coating layer has a decreased thickness relative to that of a catalyst base material; and an exhaust gas treatment system using the same. In the exhaust gas treatment catalyst for catalytically removing nitrogen oxides from an exhaust gas by using ammonia as a reducing agent and simultaneously decomposing and removing unreacted ammonia, a coating layer comprising platinum supported on titania is formed on a surface of a porous catalyst base material comprising titania and at least one compound selected from oxides of vanadium (V), oxides of tungsten (W) and oxides of molybdenum (Mo).

An improved method and apparatus for cooling the under-car channel of a tunnel kiln while minimizing migration of air between the above-car and under-car channels involves controlling or equalizing the mass flow of cooling air directed through the under-car channel and in particular through individual undercarriage cooling zones which can match individual heating zones of the tunnel kiln.

The invention discloses a preparation method of a high-thermal-conductivity low-leakage phase-change composite. The method includes: taking a phase-change material and thermal-conductive filler in the mass ratio of 0.1%-1% for melt mixing at the temperature above the melt temperature of the phase-change material for 10min, and taking out the mixture for cooling prior to breaking into granules to obtain modified filler; taking the phase-change material and a support material in the mass ratio of 0.1%-10% for melting at the temperature above the melting temperature of the support material and the phase-change material for 20min, and taking out the molten materials for cooling prior to breaking the materials into granules to obtain a modified support material; adding the modified thermal-conductive filler and the modified support material in the proportion of 1:9-9:1 into the phase-change material counting for 40-50% of total mass for melting the the temperature above the melting temperature of the support material and the phase-change material for 30min prior to obtaining a mixed composite; pouring the mixed composite into a preheated mould, applying certain pressure to the mould, maintaining the pressure for 20min, and performing cooling and demoulding to obtain the high-thermal-conductivity low-leakage phase-change composite. Compared with the prior art, the preparation method has the advantages of simplicity, low cost and chip and available raw materials.

A fluid sealing gasket is provided which comprises an outer guide ring, a serrated profile sealing element engaged to the outer guide ring and extending radially inward therefrom and an inner attachment ring engaged to the serrated profile sealing element and extending radially inward therefrom. An inner barrier pillow is formed about the inner attachment ring and extends radially inwardly therefrom. A graphite sealing element facing is formed about the serrated profile core, the serrated profile sealing element facing being disposed in abutting contact with the inner barrier pillow.

The invention relates to a pipe-bundle-builtin isothermal-shift reactor. According to the pipe-bundle-builtin isothermal-shift reactor, axial annular pipe bundles, which are builtin and are uniformly distributed in a catalyst bed layer along circumferential direction, are adopted to shift out heat of reaction, so as to realize isothermal shift; and a central pipe bundle which is built in a central pipe is adopted to preheat raw material gas entering the reactor, so as to realize the builtin of a gas-gas heat exchanger. The isothermal-shift reactor comprises a pressure-bearing shell, a catalyst basket, the axial annular pipe bundles, the central pipe and the central pipe bundle; and the axial annular pipe bundles consist of upper and lower annular pipe boxes, upper and lower annular pipe sheets and heat exchange tubes. According to the pipe-bundle-builtin isothermal-shift reactor, due to builtin pipe bundles, the manufacturing cost of equipment is effectively reduced; due to an end-part bent structure for the heat exchange tubes, the size of the pipe sheets is effectively reduced; due to a heat insulating layer laid between the pipe sheets and the high-temperature catalyst bed layer, the contact between pipe end weld spots and a bed layer high-temperature area is effectively isolated, the probability of leakage is lowered, and the reliability of equipment is improved; and the pipe-bundle-builtin isothermal-shift reactor is compact in structure, low in manufacturing cost, relatively easy in maintenance, high in reliability, complete in function and high in applicability.

The invention discloses a LeakView leakage control and management system for an urban water supply pipe network. The control and management system comprises a partitioned management system, a leakage noise online monitoring system and a water hammer early warning and monitoring system, the partitioned management system makes the water supply pipe network to form a partitioned management mode from the factory-leaving water yield, first-level partition, second-level partition, DMA to user terminal multi-level water units, all the water units are scientifically managed through a water balance test, a pressure control strategy with the optimal water saving effect and the optimal economic matching performance is made through a response mechanism of the leakage of the water supply pipe network to the pressure, leakage noise is monitored on line by using terminal noise monitoring equipment instead of leakage detection by manual listening, the noise is displayed in the form of data, a region where the leakage is suspected to exist is found through comparative analysis of the key data, the water hammer early warning and monitoring system adopts a transient flow pressure fluctuation situation of a network system to be combined with a big data technology, and therefore the rapid change of the pressure of the pipe network system can be monitored on line, an alarm for the abnormal pressure change situation can be given in real time, on-line early warning can be realized, the data can be deeply excavated and analyzed, and water hammer protection can be made.

The invention discloses a water supply pipe network management system. The system comprises a DMA life cycle management module and a DMA data analysis module, wherein the DMA life cycle management module comprises a DMA engineering management unit, a DMA management ceiling unit, a DMA maturity grading unit and a DMA consultative management unit; and the DMA data analysis module comprises a DMA leakage and loss source analysis unit, a new loss alarming unit and a zoning evaluation unit. The water supply pipe network management system provided by the invention is a Smart DMA, which fully utilizes a large amount of data recorded by the system; through technologies such as a self-developed algorithm, a simulation technology, a clustering algorithm, a chaos genetic algorithm, an interactive query and the like, useful information is extracted and specifically used for guiding practical production and marketing and leakage management; application scenes and specifications are deeply and effectively mined, so that the leakage control difference management is realized and the working efficiency is improved; and multiple technical means are adopted in the aspects of solving the leakage problem and saving water, so that the input cost is effectively reduced.

A connector assembly is disclosed. The connector assembly comprises a connector having an internal conical shaped bore dimensioned so that a capillary column and auxiliary tubing can be press-fit into the bore, and an auxiliary length of cylindrical tubing having an inner diameter dimensioned so that a close fit is created when a capillary column is inserted through the auxiliary tubing and having an outer diameter dimensioned so that a fluid seal is created when the auxiliary tubing is press-fit into the bore.

A plasma processing apparatus includes a mounting table for mounting thereon an object to be processed, an electrode connected to a high frequency power supply, an electrical state setting unit for setting an electrical state of the mounting table to a conducting state or a floating state, and a controller for controlling the high frequency power supply to apply a high frequency power to the electrode and controlling the electrical state setting unit to set an electrical state of the mounting table to a floating state. Further, a radical produced from a cleaning gas by the applied high frequency power is made to have a contact with the mounting table.

The diaphragm valve uses a metal dish-type diaphragm set to control the inflow and outflow of fluid. The metal dish-type diaphragm set is above an air flow channel to control the stem above the metal dish-type diaphragm set, and the air will be blocked by pressing the metal dish-type diaphragm to make it fit the metal valve base in the air flow channel; this non-metal valve base is fixed in the air flow channel by a fixed shrunk ring with a taper cross section, and the in-between metal diaphragm in the metal dish-type diaphragm set is annular in the center to reduce the metallic friction between metal diaphragms, to increase application times and to lower the leakage rate of the diaphragm valve.

The invention relates to a device and a method for detecting gas-liquid diffusion processes by using an MRI technique, and belongs to the technical field of chemical engineering and petroleum engineering. The device comprises a magnetic resonance imaging system and a dual chamber pressure attenuation system. The magnetic resonance imaging system is provided with a rock core clamper in a magnetic resonance imaging instrument which is electrically connected with a data acquisition and processing system. According to the device and the method for detecting gas-liquid diffusion processes by using the MRI technique, proton density images, longitudinal and transverse relaxation and diffusion tensor distribution images of fluids in porous media can be measured in real time, visually and with no damage through the MRI technique. Quantitative analysis can be performed on porous medium porosity, permeability, saturation level and the like; an improved dual chamber pressure attenuation method can reduce the leakage rate, and confirm the initial gas density conveniently and accurately; and a magnetic suspension balance can monitor gas density changes in real time, and accordingly, deficiencies of traditional dual chamber pressure attenuation methods are compensated.

The invention discloses a cylinder type lithium ion battery cell and making method thereof; wherein the making method of the cylinder type lithium ion battery cell includes the following steps: (1) making an aluminium lug and a nickel lug; (2) making a positive plate and a negative plate by respectively welding the aluminium lug and the nickel lug with a positive substrate and a negative substratefirmly; (3) obtaining an aluminium plastic composite membrane with dual circular arc structure by adopting a mould with circular structure to punch the aluminium plastic composite membrane; (4) winding the positive plate, the negative plate and a diaphragm in to a winding core; (5) placing the winding core into the aluminium plastic membrane for sealing the two end faces, so as to obtain sealed semi-finished product cell; (6) baking the semi-finished product cell and then injecting electrolyte containing Li<+>, and carrying out precharge after the semi-finished product cell is laid for a period of time; (7) vacuumizing and sealing the side of the cell after precharge, and then cutting excessive aluminium plastic composite membrane, so as to the obtain finished product cell.

The invention relates to a fingertip seal structure and a back baffle plate thereof. The fingertip seal structure comprises a front baffle plate (1), a back baffle plate (2) and a plurality of layers of fingertip sheets (3) arranged between the front baffle plate and the back baffle plate, wherein each fingertip sheet is provided with a finger body (6) being a gap form the inner diameter position, and the finger bodies (6) between adjacent fingertip sheets (3) are mutually staggered. A plurality of arc-shaped pressure balance chambers (4) are arranged in the back baffle plate (2), the shape and the arrange means of the arc-shaped pressure balance chambers are consistent with the finger bodies (6), and the width is not larger than that of the finger bodies (6). Space exists between the arc-shaped pressure balance chambers (4) and the inner diameter of the back baffle plate (2), and at the same time the arc-shaped pressure balance chambers (4) are provided with through holes (5) communicated with the back baffle plate (2). The fingertip seal structure eliminates sealing lag and at the same time still can prevent the high-pressure gas in the arc-shaped pressure balance chambers from directly leaking to a low-pressure chamber, so the fingertip seal structure has good sealing performance.

The invention provides a pressure regulating valve, which comprises a valve body, a flow guide sieve sleeve, a double-piston assembly and a regulating mechanism, wherein a circulation part of the flow guide sieve sleeve is provided with a plurality of through holes extending in the axial direction of the flow guide sieve sleeve, the double-piston assembly comprises a pressure regulating piston and a balance piston and can move in the axial direction along the inner wall surface of the flow guide sieve sleeve, a pressure balance cavity is formed between the pressure regulating piston and the balance piston, and the regulating mechanism is used for controlling the flow rate and the pressure of fluid in the pressure balance cavity so that the double-piston assembly realizes the synergistic effect in the axial direction of the valve body for controlling the engaging position of the pressure regulating piston and the inner wall surface of the flow guide sieve sleeve. The pressure regulating valve provided by the invention can realize the self adaption to the pressure regulation of the pressure regulating valve, in addition, the safety is ensured, and meanwhile, the pressure at the outlet side of the pressure regulating valve is reliably stabilized in a proper range.

The invention provides a modified asphalt waterproof coiled material which comprises an upper surface layer, a modified asphalt layer, a core layer, fiberglass gridding cloth, a self-stick layer and an isolating membrane. The asphalt layer is prepared from the following raw material components: matrix asphalt, a modifying agent, softening oil, a reinforcing agent, regenerated epoxy resin powder, an inorganic filler and elastic granules. The self-stick layer is prepared from the following raw material components: matrix asphalt, a modifying agent, SBR rubber, SIS thermoplastic rubber, regenerated epoxy resin powder, elastic granules, rubber oil, tackifying resin and talcum powder. The waterproof coiled material provided by the invention is low in cost, less in energy consumption, good in mechanical performance and free of fire risk.

A mica based compressive seal has been developed exhibiting superior thermal cycle stability when compared to other compressive seals known in the art. The seal is composed of compliant glass or metal interlayers and a sealing (gasket) member layer composed of mica that is infiltrated with a glass forming material, which effectively reduces leaks within the seal. The compressive seal shows approximately a 100-fold reduction in leak rates compared with previously developed hybrid seals after from 10 to about 40 thermal cycles under a compressive stress of from 50 psi to 100 psi at temperatures in the range from 600° C. to about 850° C.

Provided is an online adjustable closing force gas lubricating mechanical sealing device. The online adjustable closing force gas lubricating mechanical sealing device comprises an axial moving ring positioning ring, a sealing end cover, a moving ring seat, a piston, a working spring, a piston limiting ring, a pushing ring, a static ring, a moving ring and a sealing cavity. The moving ring is fixed to the moving ring seat and rotates along with a shaft. The static ring is arranged on the sealing end cover. A piston cavity is arranged inside the sealing end cover. The sealing end cover is provided with an outer gas supplying channel, and the sealing end cover is communicated with one side of the piston cavity. The working spring is arranged between the other side of the piston and the static ring. The piston moves along the piston cavity in the axial direction to change the compression amount of the working spring. The other side of the piston is exposed inside the sealing cavity. The sealing cavity is communicated with a buffer gas channel. By adjusting the outer gas supplying pressure, the compression amount of the working spring can be adjusted, and therefore online adjusting on the sealing closing force can be achieved.

The invention relates to a reciprocating shaft magnetic liquid sealing structure, which comprises a first bearing, a first magnetic-isolated ring, a first pole piece, a first O-shaped rubber gasket ring, a permanent magnet, a second O-shaped rubber gasket ring, a second pole piece, a second magnetic-isolated ring and a second bearing, which are sequentially and closely propped against an external nested inner lug boss, wherein an end cover is fixed on an outer jacket through a bolt, and the second bearing is compressed. The inner annular surface of the second pole piece (13) is provided with a left, a middle and a right counter bores, elastic rings (T) with the quantity of N+1 and trapezoid sealing gears (C) are arranged at intervals from each other to be closely arranged inside the middle counter bore, N is a positive integer of 1 to 8, the trapezoid sealing gears and the elastic rings, which are closely lined at intervals, are fixedly connected with the second pole piece in a threading way through bolts and retainer rings (15), and the trapezoid sealing gears with the quantity of N are lined up in the expansion direction of the identical inner holes; and the structure of the first pole piece (7) is completely identical to that of the second pole piece. The problems of the conventional reciprocating shaft magnetic liquid sealing structure that the magnetic liquid runs off, the sealing service life is shortened, and the leakage rate is increased can be solved.

The invention provides an angle information assisted centralized multi-sensor multi-hypothesis tracking (CMS-MHT) method, which is implemented through the following steps: (1) forecasting a flight path; (2) forming all possible flight path-measurement correlated hypothesises at the current moment, and calculating angle information assisted flight path scores; (3) pruning a flight path tree; and (4) carrying out multi-sensor filtering on the flight path. According to the invention, when measurement errors of the sensors are small, a flight path score which is in line with the actual situations is obtained by adopting an angle information assisted flight path score calculating method, so that the uncertainty of flight path-measurement correlated hypothesizes is reduced, and in comparison with a traditional CMS-MHT method, the method has the advantages that a better tracking effect is obtained, the track leakage rate is reduced, and the integrity of flight paths is enhanced.

The invention discloses a header tank divided-flow heat-storage counter flow heat exchanger, which comprises a left header tank and a right header tank which are connected with a warm air water inlet, a warm air water outlet, a tap water inlet and a tap water outlet, wherein, a plurality of tap water heat-absorbing pipes are connected with the left and right header tanks; warm air heat supply pipes are connected through tap water heat-absorbing pipes; the warm air heat supply pipes are serially communicated with each other by heat supply communicating pipes; one end of each warm air heat supply pipe is connected with the warm air water inlet, while the other end is connected with the warm air water outlet; and a plurality of water insulation boards is alternatively connected the inside of the left and the right header tanks in order to separate the left and right header tanks to obtain the oriented flow channel. The counter flow heat exchanger of the invention has the advantages that: firstly the heat exchange efficiency is high and the temperature of the outlet water is high; secondly the joints of the heat supply pipes are arranged on the same level of axis line, which is suitably installed in household-measured users of the new heat supply pipe network unit, in particular to the needs of the three northeast provinces; thirdly the users can take a shower in the heat supply region of low temperature, and the heat-absorbing pipes at heat supply region of high temperature is free from scale formation; finally the counter flow heat exchanger is totally made of stainless steel, thereby saving brass pipe, reducing the cost and producing the clean water by exchange.

The invention discloses an electronic expansion valve and a manufacturing method thereof. The electronic expansion valve comprises a shell component and a valve seat assembly. The valve seat assembly comprises a first connecting pipe and a second connecting pipe which are located on the same straight line. A main valve cavity is formed by the valve seat assembly, an included angle of the acute angle is formed by the main valve cavity and the first connecting pipe, the valve seat assembly is of an integral structure and is fixedly connected with the shell component through welding, and the preset distance is reserved between the radial extending line of the welding position of the valve seat assembly and the shell component and the first connecting pipe. According to the electronic expansion valve, due to the fact that the preset distance is reserved between the radial extending line of the welding position and the first connecting pipe, when a valve body rotates relatively to carry out welding, the welding can be smoothly carried out without the obstruction of the first connecting pipe, and the integrated valve body is formed. Compared with a thread connecting mode in the background technology, the electronic expansion valve is of an integral structure, and the leakage rate of products can be obviously reduced; meanwhile, the thickness of materials does not need to be increased, the quality of the materials does not need to be improved, and the production cost of the products can be effectively controlled.

The thermal insulation system of the present invention is for non-vacuum applications and is specifically tailored to the ambient pressure environment with any level of humidity or moisture. The thermal insulation system includes a multilayered composite including i) at least one thermal insulation layer and at least one compressible barrier layer provided as alternating, successive layers, and ii) at least one reflective film provided on at least one surface of the thermal insulation layer and / or said compressible barrier layer. The different layers and materials and their combinations are designed to provide low effective thermal conductivity for the system by managing all modes of heat transfer. The thermal insulation system includes an optional outer casing surrounding the multilayered composite. The thermal insulation system is particularly suited for use in any sub-ambient temperature environment where moisture or its adverse effects are a concern. The thermal insulation system provides physical resilience against damaging mechanical effects including compression, flexure, impact, vibration, and thermal expansion / contraction.

The invention discloses a system for calibrating the leak rates of vacuum leak holes of different leak indication gases. The system comprises a helium mass spectrum leak detector, a standard container, an argon source, a vacuum leak hole to be calibrated, a leak indication gas source, a constant volume chamber, a vortex molecular pump and a turbine mechanical pump; the vortex molecular pump and the turbine mechanical pump are connected with the constant volume chamber and the standard container by pipelines in sequence; one end of the vacuum leak hole to be calibrated is connected with the leak indication gas source by a pipeline, the other end is connected between the standard container and the constant volume chamber, and the helium mass spectrum leak detector and the argon source are respectively connected to the connecting pipeline. Besides, the system can obtain a conversion relation between leak rates when different leak indication gas media are quickly measured using the helium mass spectrum leak detector, via the magnitude of the leak rate of the leak hole measured by a constant volume method and in combination with the leak rates, measured by the helium mass spectrum leak detector, of vacuum leak holes of different leak indication gas media. The system is reasonable in design, simple in structure and convenient to operate, and can be used for calibrating the leak rates of vacuum leak holes of different leak indication gases.

The invention relates to the technical field of computers, and provides a paperless online examination method and system. The method comprises step that a management terminal receives examiner identity identification information sent by a server, acquires identity identification information input by a user, matches the examiner identity identification information and the identity identification information, and if the matching is successful, according to paper identifier information input by the user, downloads the corresponding electronic paper from the server and sends the electronic paper to each examination terminal; the examination terminals receive the corresponding electronic paper sent by the management terminal, display the electronic paper, acquire answers input by the examinees, and send the answers of the examinees to the server. Compared with the prior art, the method and system are characterized in that by use of an examination service server system based on the Internet, examination data can be directly downloaded and examination results can be directly uploaded, so safety of the examination is improved, probability of leakages of topics and answers is reduced, workload of workers is reduced and the whole process of the examination is quite highly efficiently and quickly achieved.