78 results about "Temperature jump" patented technology

The invention discloses a cladding light filtering structure for filtering out cladding light in a double-cladding or multi-cladding fiber laser system and a manufacturing method of the cladding light filtering structure. The cladding light filtering structure comprises an optical fiber and a filtering material coating layer, wherein a protective layer and an outer cladding layer of the optical fiber are removed, and a section of glass cladding layer is exposed. The refractive index of the filtering materials is higher than the refractive index of the outer cladding layer of the optical fiber, and the coating layer of the filtering materials is the filtering materials and is coated in a subsection mode. Due to the fact that refractive index, coating length and coating space of the filtering materials are matched, filtering quantity of all sections is roughly the same, highest temperature jump of an optical filter in a working state is reduced, reliability of the system is improved, and the more the subsections and the types of the materials are, the better the effect is.

The invention discloses a fruit / vegetable drying device and a working method thereof. With the fruit / vegetable drying device and the working method thereof, more fruit / vegetable windswept area is provided, the drying effect is better, the temperature at a baking area is uniform, and temperature jump can be avoided during the humidity elimination, so that the product quality is ensured. The fruit / vegetable drying device comprises a box body and a bidirectional circular drying system, wherein a baking area and a heating area are formed in the box body; a separation plate is arranged between the baking area and the heating area; an upper air vent is arranged at the top of the separation plate and a lower air vent is arranged at the bottom; a heating device and an air feeding device are arranged in the heating area; the bidirectional circular drying system comprises a counter-rotation circulating fan which is arranged in the heating area and located above the heating device; and the upper air vent, the counter-rotation circulating fan, the heating device and the lower air vent are communicated in sequence. The fruit / vegetable drying device provided by the invention is capable of ensuring that the temperature at each point in the baking area is more even.

The invention discloses an underground pipe network leak detection method. The underground pipe network leak detection method includes following steps: a, performing infrared, ultraviolet or terahertz camera shooting on an area where a pipeline is located; b, performing gray processing on a captured image, identifying gradient change in the image by using an edge detection method based on an isoline principle so as to identify gradient change of temperature or inert gas concentration in the filmed area, and confirming the boundary of a temperature jump area where temperature jump exists or the boundary of an inert gas concentration jump area where inert gas concentration jump exists according to preset gradient jump change threshold value; c, confirming an underground pipe network leak area according to the boundary of the temperature jump area or the boundary of the inert gas concentration jump area. The underground pipe network leak detection method can rapidly and accurately confirm underground pipe network leak points.

The invention discloses a bearing temperature prediction and alarm diagnosis method based on an LSTM model. Firstly, a bearing temperature prediction model is generated, model input data is obtained according to the real-time monitoring temperature, and then target shaft position temperature data is predicted; and finally, the running state of the bearing is judged according to a temperature alarmmechanism and an alarm result is output. According to the invention, temperature prediction of the target shaft position is carried out through the auxiliary shaft position temperature value; a long-short-term memory network model is adopted; the bearing fault alarm system based on the temperature sensor is prevented from being disturbed by temperature jump and temperature keeping unchanged in the using process, false alarm and missing alarm are avoided, the incidence relation in the time sequence can be analyzed, the trend of time sequence data is predicted, and meanwhile the defect that other neural networks cannot be predicted for a long time is overcome. And temperature alarm can be carried out more accurately.

Intelligent antifog resin lenses and a formed glass preparing method are composed of lens frames (1), lens legs (2), the intelligent antifog resin lenses (3), an intelligent control circuit plate (4), a lithium battery (5), a control box (6) and a flexible circuit plate (7) and a magnetic connector (8). According to the intelligent antifog resin lenses and the formed glass preparing method, a pair of intelligent antifog glasses is formed, and the pair of intelligent antifog glasses is capable of automatically removing fog which is formed on the lenses due to temperature jump, guaranteeing that transparency of the lenses can not be affected by any water vapor and bringing convenience for work and lives of users.

The invention discloses an intelligent analysis method based on distributive optical fiber temperature measurement. The intelligent analysis method based on the distributive optical fiber temperature measurement comprises the following steps that partitioned management is conduced on a temperature measurement cable, and an optical fiber temperature measurement device is installed; an alarming parameter is set in a background data processing system, and the distributive optical fiber temperature measurement device reports the real-time temperature measurement data; every time a current temperature value is received, a system conducts temperature jump analysis once on the temperatures collected in each partition area, and if an analysis value exceeds a threshold value, temperature jump alarming is conducted; every time the current temperature value is received, the system conducts slow change analysis, the temperature is compared with the highest temperature, the lowest temperature, the environment temperature, the average temperature difference and a temperature difference of each partition area, and when the temperature values exceed set numerical values, slow change temperature alarming is conducted. According to the intelligent analysis method based on the distributive optical fiber temperature measurement, analysis and filtering are conducted on the sudden change and the slow change of the temperature, when the operation state of the cable and the temperature of the surroundings fluctuates abnormally or a fault is caused, early warning can be automatically conducted, and the safety operation level of a power cable is further improved.

The invention discloses a temperature change detection method for the environment of a battery and a temperature change detection device thereof. The temperature change detection method comprises the steps that A. battery temperature is acquired in real time and the battery temperature charge rate is calculated; and B. when the battery temperature charge rate is judged to be greater than a threshold, a preset temperature corresponding matrix is inquired according to the current battery temperature and the battery temperature charge rate and the current environment temperature is acquired so that the accurate environment temperature can be immediately acquired when the environment temperature jumps or sharply changes, and the problems that an existing mobile terminal adopts a temperature-sensitive resistor to detect temperature and the change of the resistance value of the temperature-sensitive resistor is slow and cannot be timely detected can be solved.

The invention provides a biaxial uniaxial tension device for in-situ structure detection in combination with the scattering of X-rays and an experimental method of the biaxial uniaxial tension device. The device comprises a high-precision servo motor (1), a torque sensor (2), a precise gear (3), a heating furnace (3), a reverse tension shaft (5) and a Labview software control system (6). A guide rail, the precise gear (3) and a reverse tension rod are adopted for transmission. The rotating speed of the servo motor (1) and the rotational displacement are controlled by the Labview to realize precise displacement and speed tension control. The temperature distribution of the heating furnace (3) is uniformed and the thermal degradation at high temperature of samples is reduced by forced nitrogen flow. A temperature monitoring point is preset in the heating furnace (3) and a temperature controller is adopted to precisely control the temperature. Temperature jump is realized between two heating furnaces (3) of different temperature. The device has the advantages of small volume, light mass, simplicity in disassembling and installing and the like, is particularly suitable for the combination of synchrotron radiation experimental line stations and is a good device for studying the crystallization of polymer melt induced by a flow field.

The invention relates to a catalyst for synthesizing oxalate by a CO coupling reaction and a preparation method thereof; the catalyst adopts metal wire mesh as a skeleton; a carrier coating is coated on the surface of the metal wire mesh; the carrier coating is loaded with active components and additives on the surface. Compared with the prior art, with the proviso that the catalytic activity is maintained to be the same, the catalyst of the invention greatly reduces the precious metals active component using amount per unit volume of the catalyst, significantly reduces the pressure drop of a catalyst bed layer, effectively decreases the radial temperature difference of the catalyst bed layer, improves the heat shift problem during the reaction process, and solves the problem of easy temperature jump when a traditional honeycomb catalyst is used in the reaction system.

The invention discloses an earth-rockfill embankment seepage saturation surface fiber monitoring apparatus and method. The apparatus comprises a DTS, a fiber sensing unit and a fiber heating unit, the fiber sensing unit is connected with the DTS, the fiber heating unit is connected with the fiber sensing unit, the fiber sensing unit comprises armored fibers and a fiber layout frame, the fiber layout frame is a rectangular frame, width d of the rectangular frame is axial length of an earth-rockfill embankment body to be monitored, length l of the rectangular frame is section width of the earth-rockfill embankment body, and n points are marked to both long sides of the rectangular frame; by acquiring and analyzing time and strength information of Raman back-reflecting light generated by laser pulse after being injected from an injection end of a linear multimode temperature-sensing fiber and being propagated in the fiber, corresponding position and temperature information is acquired, and a position of seepage saturation surface is acquired according to a temperature jump point. The apparatus and method have the advantages that operating is simple, the apparatus and method are suitable for long-term use and are high in durability and reliability, seepage surface positioning is accurate, and monitoring precision is high.

The invention discloses a coke-burning method for hydrocarbon conversion catalyst regeneration and a structure of a coke-burning area of a regenerator. The invention solves the disadvantage of the temperature jump risk in a coke-burning area of a hydrocarbon conversion catalyst in the prior art. The method comprises the following steps: allowing a catalyst to be regenerated to enter a coke-burning area of a radial catalyst moving bed under gravity, allowing the catalyst to contact an oxygen-containing regenerating gas and burning out coke deposits on the catalyst, and allowing the catalyst to enter a chlorine oxidation area, wherein the coke-burning area of the catalyst moving bed comprises an inner screen and an outer screen; the lower diameter is larger than the upper diameter of the outer screen; the upper and the lower parts of the outer screen are connected by a conical structure; the outer screen with different diameters and the inner screen forms, from up to down, an upper quick-burning section, an intermediate transition section, and a lower overheating section of the coke-burning area; and the thickness ratio of the catalyst bed layers of the quick-burning section and the overheating section is 0.25-1, and the height ratio is 1-8.

The invention relates to a temperature detecting device, a temperaure detecting method and a liquid crystal driving device. The temperature detecting device comprises a state machine, a frame frequency selection unit and a frame frequency output unit. When a current temperature value jumps around a certain critical temperature value, the state machine judges whether the difference value of the current temperature value and the critical temperature value is within the preset range; if the difference value of the current temperature value and the critical temperature value is within the preset range, the state machine determines that the current state is the previous state; if the difference value of the current temperature value and the critical temperature value is out of the preset range, the state machine determines that the current state is the state corresponding to the current temperature value. The frame frequency selection unit connected with the state machine is used for selecting the frame frequency corresponding to the current state according to the current state determined by the state machine. The frame frequency output unit connected with the frame frequency selection unit is used for outputting the frame frequency. When the temperature jumps frequently in a smaller range, the temperature detecting device can avoid the frequent jump of the frame frequency and the flicker of a liquid crystal display screen caused by the frequent jump of the frame frequency, and thus the display quality of liquid crystal display screen is enhanced.

The present invention relates to a Fe-based fluidized bed catalyst for Fischer-Tropsch synthesis and preparation method thereof. The invention is aimed to solve the problems in the prior art that because Fischer-Tropsch synthesis is a strongly exothermic reaction, when a fixed bed is used, heat dissipation in the reactor is difficult and temperature jump is easy to occur in the reaction so as to allow an easy inactivation of the catalyst; when a fluidized bed is used, reaction temperature is high and the selectivity of ingredients of gasoline and diesel oil is relatively low. The catalyst of the invention is composed of at least one oxide selected from oxides of Si or Al as a carrier, and an active component comprising the composition of the chemical formula in terms of atomic ratio: Fe100AaBbCcDdOx, wherein A is selected from at least one of alkali metals or alkaline earth metals; B is selected from at least one of La or Ce; C is selected from at least one of Cu or Mn; D is selected from at least one of Co or Ni. The catalyst is applicable to the industrial production of Fischer-Tropsch synthesis.

The invention discloses a method of super-critical Fischer-Tropsch synthesis, using molten-iron as catalyst to convert synthetic gas (CO+H2) into hydrocarbon in the presence of supercritical media. The process comprises as follows: mixing the synthetic gas and supercritical media, performing super-critical Fischer-Tropsch synthesis under the conditions of temperature of 180-350DEG C, pressure of 3.0-10.0MPa and synthetic gas airspeed of 1000h-1-30000h-1 and converting the synthetic gas into liquid fuel. The molten-iron catalyst has the advantages of easy obtaining of raw material, strong abrasive resistance, high space time yield, high selectivity of olefin, simple preparing process, stable catalyst property, more suitability of industrial production and the like. Under the same reaction condition, compared with gas-phase and liquid-phase Fischer-Tropsch synthesis, the super-critical Fischer-Tropsch synthesis can reduce temperature jump of beds, decrease carbon deposit on surface of the catalyst, prevent devitalization of the catalyst and prolong the service life of the catalyst. In terms of reaction property, the invention can increase conversion rate of CO, reduce selectivity of methane and increase selectivity of C5+ and olefin in products.

The invention discloses a self-inspection method, a self-inspection device for an air conditioner and the air conditioner and relates to the technical field of air conditioners. The self-inspection method for the air conditioner comprises the following steps: acquiring a temperature change rate of a coil of the air conditioner; and judging the operating condition of the air conditioner according to a relationship between the temperature change rate and a preset change rate and duration. By judging the operating condition of the air conditioner by means of the temperature change rate of the coil, a temperature jump of the coil can be obtained, so that abnormality of the air conditioner can be found and removed immediately without judging the operating abnormality of the air conditioner when the temperature of the coil of the air conditioner reaches the abnormal temperature. In addition, compared with a condition of judging the operating condition of the air conditioner by acquiring the single temperature value, the operating condition of the air conditioner is judged more accurately favorably by feeding back the temperature trend information of the coil of the air conditioner by acquiring the coil temperature change rate. The self-inspection device for the air conditioner and the air conditioner are used for implementing the method, so that the self-inspection device has the same beneficial effect.

The invention discloses a roasting flue gas heat recovery and dust suppression system of a zinc oxide production device. The roasting flue gas heat recovery and dust suppression system comprises a box body, wherein a flue gas inlet and a flue gas outlet are formed in the box body, a plurality of heat exchange assemblies are longitudinally arranged on the box body, each heat exchange assembly comprises a feed box, a discharge box and a plurality of heat exchange tubes which are used for communicating the feed box with the discharge box, all of the heat exchange tubes are positioned on the inner wall of the box body, cooling media respectively flow into each feed box, then flow to each heat exchange tube and flow out from each discharge box at last, and air mechanical force is regularly sent to shake off dirt and dust on the outer walls of the heat exchange tubes, so that dirtiness resistance is reduced, and the flue gas heat exchange effect is guaranteed. According to the heat recovery and dust suppression system, the plurality of heat exchange assemblies which are mutually independent are arranged on the box body, the heat of a part of flue gas is carried away by each heat exchange assembly, so that gradual cooling of the box body is realized, and a stable controllable temperature gradient field is formed in a heat exchange flue due to the change of the flue gas temperature, so that gradual dust suppression is realized, and the phenomenon that a pipeline is blocked by powdered zinc oxide which is suddenly cooled due to temperature jump is avoided. The roasting flue gas heat recovery and dust suppression system has the advantages of simple structure and reliability in operation.

The invention provides a longitudinal cracking bleed-out detection and prediction device for a continuous casting sheet billet and a detection method thereof. The device is mounted at the area between a first sector section and a second sector section below a slab casting machine crystallizer and comprises high-temperature resistance metal ceramic probes, metal guide rods, a guide groove, hydraulic oil cylinders, hydraulic locks, one-way throttle valves, a reversing valve, a hydraulic pump, an oil tank and a PLC control system. According to the method, the high-temperature resistance metal ceramic probes move back and forth on the continuous casting sheet billet, so that the actual temperature of the continuous casting sheet billet is detected, and then the temperature is transmitted to the PLC control system; when the detected temperature jumps above 50 DEG C, the PLC control system gives out an alarm automatically, at the moment, the system is automatically switched to be in an accident control mode or a manual operation mode, the casting speed of the continuous casting sheet billet is decreased so that longitudinal crack diffusion can be reduced, and therefore bleed-out of the sheet billet because of longitudinal cracking is prevented. By means of the device and method, the bleed-out probability of the continuous casting sheet billet due to longitudinal cracking is lowered, the device and method can be used for longitudinal cracking prediction control over a continuous casting machine apart from bleed-out prediction, and the promotional value is high.

Provided is a method for improving transient expression of recombinant proteins through improvement of transfection efficiency, wherein the transfection efficiency is improved through changing of environment of cells before and after transfection. The method enables expression index of the transient transfection recombinant proteins to be improved by 37% to 56%.

The embodiment of the invention discloses a blast furnace blower temperature monitoring method and system and relates to the technical field of monitoring. The blast furnace blower temperature monitoring method comprises the steps that the current temperature of a temperature detecting point is periodically collected through a temperature collecting module and is compared with a preset alarming temperature, and the temperature monitoring result of the temperature detecting point is generated; and the temperature difference absolute value is calculated through the current temperature of the temperature detecting point and the historical temperature of the temperature detecting point and is compared with a preset jumping alarming temperature, and the temperature jumping monitoring result of the temperature detecting point is generated. The condition that the temperature of the temperature detecting point is jumped due to self breakdown of the temperature collecting module is eliminated, the problem that a blast furnace blower stops due to non-self breakdown of the blast furnace blower is solved, and meanwhile, the condition that maintenance personnel of the temperature collecting module confirm the breakdown condition and overhaul the device is facilitated.

In one aspect, the present invention provides a method for enhancing the sensitivity of liquid-state NMR or MRI experiments. In general, the method involves providing a frozen sample in a magnetic field, wherein the frozen sample includes a polarizing agent with at least one unpaired electron and an analyte with at least one spin half nucleus; polarizing the at least one spin half nucleus of the analyte by irradiating the frozen sample with radiation having a frequency that excites electron spin transitions in the at least one unpaired electron of the polarizing agent; melting the frozen sample to produce a molten sample; and (d) detecting nuclear spin transitions in the at least one spin half nucleus of the analyte in the molten sample. In certain embodiments, the methods further comprise a step of freezing a sample in a magnetic field to provide the frozen sample in a magnetic field.

The invention discloses a simulation method of an acid-rain corrosion solution. The method comprises the following steps: simulating an acid-rain solution by the use of a mixed solution of ammonia sulfate and nitric acid in a test, controlling SO1<2-> concentration by the use of ammonia sulfate, and regulating pH value of the solution by the use of nitric acid; carrying out an acid-rain corrosion circulation test by selecting concrete as a test piece; and immersing the test piece in the simulated acid-rain solution for 36 h, taking out the test piece and air-drying for 1 h, drying by a drying oven of 60 DEG C for 10 h, and cooling for 1 h. Total time of the one circulation is 48 h. There are many simulation test method for research on acid-rain corrosion damage on the market. However, the tests consider no natural factors such as temperature jump, alternation of wetting and drying, sun exposure and the like which also will aggravate the damage, and few researches on acid-rain corrosion are carried out. The method of the invention makes up the above defects for the research. Through the method, durability of concrete under the action of a single factor of acid rain and multiple factors is researched, and some achievements are made.

A far infrared temperature jump microscope comprises a laser light source portion, fluorescence optical filter components, a microscope imaging system, an objective optical system, and an objective table. The fluorescence optical filter components is arranged between the laser light source portion and the objective optical system. The fluorescence optical filter components comprise a transmitting optical filter, a dichroscope and an exciter filter. The objective optical system comprises a nosepiece and the objective fixedly arranged on the nosepiece. A far infrared laser system is arranged between the fluorescence optical filter components and the objective optical system, stimulates to produce far infrared laser and gathers the far infrared laser light on the test specimen. The far infrared temperature jump microscope is capable of conducting accurate heating of micro region of the biological sample specimen, and the heating efficiency is high.

The invention provides a pulsating heat pipe heat exchanger. The pulsating heat pipe heat exchanger is characterized in that the pulsating heat pipe heat exchanger comprises a pulsating heat pipe which is made of stainless steel materials; and the pulsating heat pipe is filled with an ammonia water solution which serves as work media. Compared with other media, the pulsating heat pipe heat exchanger with the ammonia water as the media can be fast started; and because stainless steel and ammonia water are compatible, a chemical reaction of ammonia water with copper is avoided, the temperature jump starting characteristic is avoided, and the problem that the pulsating heat pipe heat exchanger cannot be used in some occasions is solved.

The invention relates to a filtering method for eliminating cast iron thermal analysis curve interference. A filtering window is arranged to filter curves in the window in different conditions, and the filtering of a thermal analysis curve is finally completed. According to the filtering method disclosed by the invention, each temperature spot on the thermal analysis curve is firstly judged to be a burr, a peak or an intrinsic temperature jump. The interferences of the burr and the peak are filtered, and the intrinsic temperature jump is retained. After the filtering treatment, the information of the intrinsic temperature jump is retained while the burr is removed, the thermal analysis curve is smoothed, and accuracy of analysis on contents of carbon and silicon is improved.

The invention discloses a distributed optical fiber temperature sensor data processing method, and belongs to the technical field of sensors. The method comprises the following steps: before continuous temperature data measured by a distributed temperature sensor is filtered using a filter template, the edge of the continuous temperature data is detected; and when the edge detection result shows that the edge is a temperature jump point, the filter template skips the edge during smooth filtering. According to the invention, before data measured by a distributed optical fiber temperature sensor is smoothly filtered, the edge in the temperature data is detected first, and then, the edge is skipped during smooth filtering. Thus, the problem that the edge point becomes smooth after edge point smoothing and the spatial positioning accuracy and temperature measurement accuracy of the system are reduced is avoided.

The invention relates to the field of specimen preservation, in particular to a specimen preservation method, a multifunctional specimen box assembly and specimen boxes. The multifunctional specimen box assembly comprises protection assemblies and connecting assemblies. The protection assemblies comprise bodies, adjusting grooves and adjusting bags. The adjusting grooves is cavity structures arranged on the bodies, the adjusting grooves communicate with holes in the first sides of the bodies, and the adjusting bags are detachably installed in the adjusting grooves. The specimen boxes can be assembled fully according to the shape of specimens. The temperature, humidity and the oxygen content inside the sample boxes can be automatically adjusted and maintained for a long time. Anti-collisionlayers can prevent the specimens from being damaged on impact. Pressure valves can prevent the specimens from being damaged by pressure jump in the opening process. Heat transfer assemblies can prevent the specimens from being damaged by temperature jump in the opening process. Stacking of the specimen boxes is convenient through camping seats. Shading covers and photosensitive glass can preventthe specimens from being damaged by excessively bright external light in the observation process. Sensors and displays facilitate the observation of internal environmental parameters.

The invention discloses a safety device for oxalate production by CO gas phase oxidative coupling, which is characterized in that the device comprises a first nitrogen gas control pipeline (1), a carbon monoxide gas control pipeline (2), a second nitrogen gas control pipeline (3), a nitric oxide gas control pipeline (4), an oxygen gas control pipeline (5), a main pressure gage (10'), a methanol or ethanol storage tank (11), a liquid pump (12), an esterification column (13), a waste water storage tank (14), a gas mixing box (15), a first pneumatic four-way valve (16), a second pneumatic four-way valve (17), a valve controller (18), a circulating pump (19), a reactor (20), a heating furnace (22), a fan (23), a control box (24), an alarm (25), an oxalate collecting tank (26), and a computer (27). The device can automatically determine whether a temperature jump occurs, carry out corresponding measures, and ensure smooth production.

The invention discloses an air conditioning control system of a rail train. The air conditioning control system is characterized in that the air conditioning control system comprises an environment temperature detecting unit, an environment temperature judging unit, a controller central processing unit, a low-temperature vehicle maintenance signal input unit, and an environment temperature jump judging unit; the controller central processing unit is used for controlling the air conditioning control system to be shifted into an equipment heating operation mode when the judging result of the environment temperature judging unit is the high-cold environment condition; and the controller central processing unit controls an air conditioning system to enter into a low-temperature vehicle maintenance mode, and when an anti-freezing judging unit is activated, the controller central processing unit starts an air conditioning system anti-freezing mode preferentially. According to the air conditioning control system, equipment of the air conditioning system can be protected, the batched equipment failure of the air conditioning system at the high-cold zone in winter is avoided, it is ensuredthat the temperature in a compartment containing the end zone can meet the comfort requirement under the high-cold environment operation condition, and frosting of the end zone or a door of the trainis effectively prevented. The invention further discloses the rail train comprising the air conditioning control system.

The invention relates to the field of heat treatment equipment, in particular to an annealing sealing device. The annealing sealing device comprises an annealing furnace. Two supports perpendicular to an inlet of the annealing furnace are symmetrically arranged on the side wall at the position of an inlet of the annealing furnace. The end portions of the two supports are provided with a connection plate. The supports are provided with sliding grooves. The sliding grooves of the two supports are internally connected with fulcrum bars in a sliding manner. The ends, far away from the sliding grooves, of the fulcrum bars are rotationally connected with rolling wheels. A sealing cover arranged on the inlet of the sealing furnace is arranged between the two rolling wheels, and the upper inner wall and the lower inner wall of the sealing cover are connected with a plurality of sets of sealing pieces in a hinged manner, wherein the sealing pieces are intersected, rolling balls are hinged to the end portions of the sealing pieces, and the end portions at the feeding position of the sealing cover are perpendicularly provided with springs connected with the connection plate. According to the annealing sealing device, the situation that high-temperature gas appearing at the inlet position of the annealing furnace scalds a worker can be avoided, workpieces can be preheated, and the temperature jump on the surfaces of the workpieces is prevented.