Using friction stir processing to produce ultrafine-grained microstructure in AZ61 magnesium al

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Friction stir welding and processing

Friction stir welding and processingR.S.Mishra a ,*,Z.Y .Ma ba Center for Friction Stir Processing,Department of Materials Science and Engineering,University of Missouri,Rolla,MO 65409,USAb Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,ChinaAvailable online 18August 2005AbstractFriction stir welding (FSW)is a relatively new solid-state joining process.This joining technique is energy efﬁcient,environment friendly,and versatile.In particular,it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding.FSW is considered to be the most signiﬁcant development in metal joining in a decade.Recently,friction stir processing (FSP)was developed for microstructural modiﬁcation of metallic materials.In this review article,the current state of understanding and development of the FSW and FSP are addressed.Particular emphasis has been given to:(a)mechanisms responsible for the formation of welds and microstructural reﬁnement,and (b)effects of FSW/FSP parameters on resultant microstructure and ﬁnal mechanical properties.While the bulk of the information is related to aluminum alloys,important results are now available for other metals and alloys.At this stage,the technology diffusion has signiﬁcantly outpaced the fundamental understanding of microstructural evolution and microstructure–property relationships.#2005Elsevier B.V .All rights reserved.Keywords:Friction stir welding;Friction stir processing;Weld;Processing;Microstructure1.IntroductionThe difﬁculty of making high-strength,fatigue and fracture resistant welds in aerospace aluminum alloys,such as highly alloyed 2XXX and 7XXX series,has long inhibited the wide use of welding for joining aerospace structures.These aluminum alloys are generally classiﬁed as non-weldable because of the poor solidiﬁcation microstructure and porosity in the fusion zone.Also,the loss in mechanical properties as compared to the base material is very signiﬁcant.These factors make the joining of these alloys by conventional welding processes unattractive.Some aluminum alloys can be resistance welded,but the surface preparation is expensive,with surface oxide being a major problem.Friction stir welding (FSW)was invented at The Welding Institute (TWI)of UK in 1991as a solid-state joining technique,and it was initially applied to aluminum alloys [1,2].The basic concept of FSW is remarkably simple.A non-consumable rotating tool with a specially designed pin and shoulder is inserted into the abutting edges of sheets or plates to be joined and traversed along the line of joint (Fig.1).The tool serves two primary functions:(a)heating of workpiece,and (b)movement of material to produce the joint.The heating is accomplished by friction between the tool and the workpiece and plastic deformation of workpiece.The localized heating softens the material around the pin and combination of tool rotation and translation leads to movement of material from the frontof Materials Science and Engineering R 50(2005)1–78*Corresponding author.Tel.:+15733416361;fax:+15733416934.E-mail address:rsmishra@ (R.S.Mishra).0927-796X/$–see front matter #2005Elsevier B.V .All rights reserved.doi:10.1016/j.mser.2005.07.001the pin to the back of the pin.As a result of this process a joint is produced in ‘solid state ’.Because of various geometrical features of the tool,the material movement around the pin can be quite complex[3].During FSW process,the material undergoes intense plastic deformation at elevated temperature,resulting in generation of ﬁne and equiaxed recrystallized grains [4–7].The ﬁne microstructure in friction stir welds produces good mechanical properties.FSW is considered to be the most signi ﬁcant development in metal joining in a decade and is a ‘‘green ’’technology due to its energy ef ﬁciency,environment friendliness,and versatility.As compared to the conventional welding methods,FSW consumes considerably less energy.No cover gas or ﬂux is used,thereby making the process environmentally friendly.The joining does not involve any use of ﬁller metal and therefore any aluminum alloy can be joined without concern for the compatibility of composition,which is an issue in fusion welding.When desirable,dissimilar aluminum alloys and composites can be joined with equal ease [8–10].In contrast to the traditional friction welding,which is usually performed on small axisymmetric parts that can be rotated and pushed against each other to form a joint [11],friction stir welding can be applied to various types of joints like butt joints,lap joints,T butt joints,and ﬁllet joints [12].The key bene ﬁts of FSW are summarized in Table 1.Recently friction stir processing (FSP)was developed by Mishra et al.[13,14]as a generic tool for microstructural modi ﬁcation based on the basic principles of FSW.In this case,a rotating tool is inserted in a monolithic workpiece for localized microstructural modi ﬁcation for speci ﬁc property enhancement.For example,high-strain rate superplasticity was obtained in commercial 7075Al alloy 2R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–78Fig.1.Schematic drawing of friction stir welding.Table 1Key bene ﬁts of friction stir weldingMetallurgical bene ﬁtsEnvironmental bene ﬁts Energy bene ﬁts Solid phase processLow distortion of workpieceGood dimensional stabilityand repeatabilityNo loss of alloying elementsExcellent metallurgicalproperties in the joint areaFine microstructureAbsence of crackingReplace multiple partsjoined by fasteners No shielding gas required No surface cleaning required Eliminate grinding wastes Eliminate solvents required for degreasing Consumable materials saving,such as rugs,wire or any other gases Improved materials use (e.g.,joining different thickness)allows reduction in weight Only 2.5%of the energy needed for a laser weld Decreased fuel consumption in light weight aircraft,automotive and ship applications3 R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78by FSP[13–15].Furthermore,FSP technique has been used to produce surface composite on aluminum substrate[16],homogenization of powder metallurgy aluminum alloy[17],microstructuralmodiﬁcation of metal matrix composites[18]and property enhancement in cast aluminum alloys[19].FSW/FSP is emerging as a very effective solid-state joining/processing technique.In a relativelyshort duration after invention,quite a few successful applications of FSW have been demonstrated[20–23].In this paper,the current state of understanding and development of the FSW and FSP are reviewed.2.Process parametersFSW/FSP involves complex material movement and plastic deformation.Welding parameters,tool geometry,and joint design exert signiﬁcant effect on the materialﬂow pattern and temperature distribution,thereby inﬂuencing the microstructural evolution of material.In this section,a few majorfactors affecting FSW/FSP process,such as tool geometry,welding parameters,joint design are addressed.2.1.Tool geometryTool geometry is the most inﬂuential aspect of process development.The tool geometry plays acritical role in materialﬂow and in turn governs the traverse rate at which FSW can be conducted.AnFSW tool consists of a shoulder and a pin as shown schematically in Fig.2.As mentioned earlier,thetool has two primary functions:(a)localized heating,and(b)materialﬂow.In the initial stage of toolplunge,the heating results primarily from the friction between pin and workpiece.Some additionalheating results from deformation of material.The tool is plunged till the shoulder touches the workpiece.The friction between the shoulder and workpiece results in the biggest component of heating.From the heating aspect,the relative size of pin and shoulder is important,and the other designfeatures are not critical.The shoulder also provides conﬁnement for the heated volume of material.The second function of the tool is to‘stir’and‘move’the material.The uniformity of microstructureand properties as well as process loads are governed by the tool design.Generally a concave shoulderand threaded cylindrical pins are used.With increasing experience and some improvement in understanding of materialﬂow,the tool geometry has evolved signiﬁplex features have been added to alter materialﬂow,mixingand reduce process loads.For example,Whorl TM and MX Triﬂute TM tools developed by TWI areshown in Fig.3.Thomas et al.[24]pointed out that pins for both tools are shaped as a frustum that displaces less material than a cylindrical tool of the same root diameter.Typically,the Whorl TM reduces the displaced volume by about 60%,while the MX Tri ﬂute TM reduces the displaced volume by about 70%.The design features of the Whorl TM and the MX Tri ﬂute TM are believed to (a)reducewelding force,(b)enable easier ﬂow of plasticized material,(c)facilitate the downward augering effect,and (d)increase the interface between the pin and the plasticized material,thereby increasing heat generation.It has been demonstrated that aluminum plates with a thickness of up to 50mm can be successfully friction stir welded in one pass using these two tools.A 75mm thick 6082Al-T6FSW weld was made using Whorl TM tool in two passes,each giving about 38mm penetration.Thomas et al.[24]suggested that the major factor determining the superiority of the whorl pins over the conventional cylindrical pins is the ratio of the swept volume during rotation to the volume of the pin itself,i.e.,a ratio of the ‘‘dynamic volume to the static volume ’’that is important in providing an adequate ﬂow path.Typically,this ratio for pins with similar root diameters and pin length is 1.1:1for conventional cylindrical pin,1.8:1for the Whorl TM and 2.6:1for the MX Tri ﬂute TM pin (when welding 25mm thick plate).For lap welding,conventional cylindrical threaded pin resulted in excessive thinning of the top sheet,leading to signi ﬁcantly reduced bend properties [25].Furthermore,for lap welds,the width of the weld interface and the angle at which the notch meets the edge of the weld is also important for applications where fatigue is of main concern.Recently,two new pin geometries —Flared-Trifute TM with the ﬂute lands being ﬂared out (Fig.4)and A-skew TM with the pin axis being slightly inclined to the axis of machine spindle (Fig.5)were developed for improved quality of lap welding [25–27].The design features of the Flared-Trifute TM and the A-skew TM are believed to:(a)increase the ratio between of the swept volume and static volume of the pin,thereby improving the ﬂow path around and underneath the pin,(b)widen the welding region due to ﬂared-out ﬂute lands in the Flared-Trifute TM pin and the skew action in the A-skew TM pin,(c)provide an improved mixing action for oxide fragmentation and dispersal at the weld interface,and (d)provide an orbital forging action at the root of the weld due to the skew action,improving weld quality in this pared to the 4R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–78Fig.3.Worl TM and MX Tri ﬂute TM tools developed by The Welding Institute (TWI),UK (Copyright #2001,TWI Ltd)(after Thomas et al.[24]).conventional threaded pin,Flared-Trifute TM and A-skew TM pins resulted in:(a)over 100%improve-ment in welding speed,(b)about 20%reduction in axial force,(c)signi ﬁcantly widened welding region (190–195%of the plate thickness for Flared-Trifute TM and A-skew TM pins,110%for conventional threaded pin),and (d)a reduction in upper plate thinning by a factor of >4[27].Further,Flared-Trifute TM pin reduced signi ﬁcantly the angle of the notch upturn at the overlapping plate/weld interface,whereas A-skew TM pin produced a slight downturn at the outer regions of the overlapping plate/weld interface,which are bene ﬁcial to improving the properties of the FSW joints[25,27].Thomas and Dolby [27]suggested that both Flared-Trifute TM and A-skew TM pins are suitable for lap,T,and similar welds where joining interface is vertical to the machine axis.Further,various shoulder pro ﬁles were designed in TWI to suit different materials and conditions (Fig.6).These shoulder pro ﬁles improve the coupling between the tool shoulder and the workpieces by entrapping plasticized material within special re-entrant features.Considering the signi ﬁcant effect of tool geometry on the metal ﬂow,fundamental correlation between material ﬂow and resultant microstructure of welds varies with each tool.A critical need is to develop systematic framework for tool putational tools,including ﬁnite element analysis R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–785Fig.4.Flared-Tri ﬂute TM tools developed by The Welding Institute (TWI),UK:(a)neutral ﬂutes,(b)left ﬂutes,and (c)right hand ﬂutes (after Thomas et al.[25]).Fig.5.A-Skew TM tool developed by The Welding Institute (TWI),UK:(a)side view,(b)front view,and (c)swept region encompassed by skew action (after Thomas et al.[25]).(FEA),can be used to visualize the material ﬂow and calculate axial forces.Several companies have indicated internal R&D efforts in friction stir welding conferences,but no open literature is available on such efforts and outcome.It is important to realize that generalization of microstructural development and in ﬂuence of processing parameters is dif ﬁcult in absence of the tool information.2.2.Welding parametersFor FSW,two parameters are very important:tool rotation rate (v ,rpm)in clockwise or counterclockwise direction and tool traverse speed (n ,mm/min)along the line of joint.The rotation of tool results in stirring and mixing of material around the rotating pin and the translation of tool moves the stirred material from the front to the back of the pin and ﬁnishes welding process.Higher tool rotation rates generate higher temperature because of higher friction heating and result in more intense stirring and mixing of material as will be discussed later.However,it should be noted that frictional coupling of tool surface with workpiece is going to govern the heating.So,a monotonic increase in heating with increasing tool rotation rate is not expected as the coef ﬁcient of friction at interface will change with increasing tool rotation rate.In addition to the tool rotation rate and traverse speed,another important process parameter is the angle of spindle or tool tilt with respect to the workpiece surface.A suitable tilt of the spindle towards trailing direction ensures that the shoulder of the tool holds the stirred material by threaded pin and move material ef ﬁciently from the front to the back of the pin.Further,the insertion depth of pin into the workpieces (also called target depth)is important for producing sound welds with smooth tool shoulders.The insertion depth of pin is associated with the pin height.When the insertion depth is too shallow,the shoulder of tool does not contact the original workpiece surface.Thus,rotating shoulder cannot move the stirred material ef ﬁciently from the front to the back of the pin,resulting in generation of welds with inner channel or surface groove.When the insertion depth is too deep,the shoulder of tool plunges into the workpiece creating excessive ﬂash.In this case,a signi ﬁcantly concave weld is produced,leading to local thinning of the welded plates.It should be noted that the recent development of ‘scrolled ’tool shoulder allows FSW with 08tool tilt.Such tools are particularly preferred for curved joints.Preheating or cooling can also be important for some speci ﬁc FSW processes.For materials with high melting point such as steel and titanium or high conductivity such as copper,the heat produced by friction and stirring may be not suf ﬁcient to soften and plasticize the material around the rotating tool.Thus,it is dif ﬁcult to produce continuous defect-free weld.In these cases,preheating or additional external heating source can help the material ﬂow and increase the process window.On the other hand,materials with lower melting point such as aluminum and magnesium,cooling can be used to reduce 6R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–78extensive growth of recrystallized grains and dissolution of strengthening precipitates in and around the stirred zone.2.3.Joint designThe most convenient joint con ﬁgurations for FSW are butt and lap joints.A simple square butt joint is shown in Fig.7a.Two plates or sheets with same thickness are placed on a backing plate and clamped ﬁrmly to prevent the abutting joint faces from being forced apart.During the initial plunge of the tool,the forces are fairly large and extra care is required to ensure that plates in butt con ﬁguration do not separate.A rotating tool is plunged into the joint line and traversed along this line when the shoulder of the tool is in intimate contact with the surface of the plates,producing a weld along abutting line.On the other hand,for a simple lap joint,two lapped plates or sheets are clamped on a backing plate.A rotating tool is vertically plunged through the upper plate and into the lower plate and traversed along desired direction,joining the two plates (Fig.7d).Many other con ﬁgurations can be produced by combination of butt and lap joints.Apart from butt and lap joint con ﬁgurations,other types of joint designs,such as ﬁllet joints (Fig.7g),are also possible as needed for some engineering applications.It is important to note that no special preparation is needed for FSW of butt and lap joints.Two clean metal plates can be easily joined together in the form of butt or lap joints without any major concern about the surface conditions of the plates.3.Process modelingFSW/FSP results in intense plastic deformation and temperature increase within and around the stirred zone.This results in signi ﬁcant microstructural evolution,including grain size,grain boundary character,dissolution and coarsening of precipitates,breakup and redistribution of dispersoids,and texture.An understanding of mechanical and thermal processes during FSW/FSP is needed for optimizing process parameters and controlling microstructure and properties of welds.In this section,the present understanding of mechanical and thermal processes during FSW/FSP is reviewed.3.1.Metal ﬂowThe material ﬂow during friction stir welding is quite complex depending on the tool geometry,process parameters,and material to be welded.It is of practical importance to understand the material ﬂow characteristics for optimal tool design and obtain high structural ef ﬁciency welds.This has led to R.S.Mishra,Z.Y.Ma /Materials Science and Engineering R 50(2005)1–787Fig.7.Joint con ﬁgurations for friction stir welding:(a)square butt,(b)edge butt,(c)T butt joint,(d)lap joint,(e)multiple lap joint,(f)T lap joint,and (g)ﬁllet joint.788R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–numerous investigations on materialﬂow behavior during FSW.A number of approaches,such astracer technique by marker,welding of dissimilar alloys/metals,have been used to visualize materialﬂow pattern in FSW.In addition,some computational methods including FEA have been also used tomodel the materialﬂow.3.1.1.Experimental observationsThe materialﬂow is inﬂuenced very signiﬁcantly by the tool design.Therefore,any general-ization should be treated carefully.Also,most of the studies do not report tool design and all processconditions.Therefore,differences among various studies cannot be easily discerned.To develop anoverall pattern,in this review a few studies are speciﬁcally summarized and then some general trendsare presented.3.1.1.1.Tracer technique by marker.One method of tracking the materialﬂow in a friction stir weldis to use a marker material as a tracer that is different from the material being welded.In the past fewyears,different marker materials,such as aluminum alloy that etch differently from the base metal[28–30],copper foil[31],small steel shots[32,33],Al–SiC p and Al–W composites[3,34],andtungsten wire[35],have been used to track the materialﬂow during FSW.Reynolds and coworkers[28–30]investigated the materialﬂow behavior in FSW2195Al-T8 using a marker insert technique(MIT).In this technique,markers made of5454Al-H32wereembedded in the path of the rotating tool as shown in Fig.8and theirﬁnal position after weldingwas revealed by milling off successive slices of0.25mm thick from the top surface of the weld,etching with Keller’s reagent,and metallographic examination.Further,a projection of the markerpositions onto a vertical plane in the welding direction was constructed.These investigations revealedthe following.First,all welds exhibited some commonﬂow patterns.Theﬂow was not symmetricabout the weld centerline.Bulk of the marker material moved to aﬁnal position behind its originalposition and only a small amount of the material on the advancing side was moved to aﬁnal position infront of its original position.The backward movement of material was limited to one pin diameterbehind its original position.Second,there is a well-deﬁned interface between the advancing andretreating sides,and the material was not really stirred across the interface during the FSW process,atleast not on a macroscopic level.Third,material was pushed downward on the advancing side andmoved toward the top at the retreating side within the pin diameter.This indicates that the‘‘stirring’’ofmaterial occurred only at the top of the weld where the material transport was directly inﬂuenced bythe rotating tool shoulder that moved material from the retreating side around the pin to the advancingR.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–789 side.Fourth,the amount of vertical displacement of the retreating side bottom marker was inversely proportional to the weld pitch(welding speed/rotation rate,i.e.the tool advance per rotation).Fifth,thematerial transport across the weld centerline increased with increasing the pin diameter at a constanttool rotation rate and traverse speed.Based on these observations,Reynolds et al.[29,30]suggestedthat the friction stir welding process can be roughly described as an in situ extrusion process whereinthe tool shoulder,the pin,the weld backing plate,and cold base metal outside the weld zone form an‘‘extrusion chamber’’which moves relative to the workpiece.They concluded that the extrusionaround the pin combined with the stirring action at the top of the weld created within the pin diameter a secondary,vertical,circular motion around the longitudinal axis of the weld.Guerra et al.[31]studied the materialﬂow of FSW6061Al by means of a faying surface tracerand a pin frozen in place at the end of welding.For this technique,weld was made with a thin0.1mm high-purity Cu foil along the faying surface of the weld.After a stable weld had been established,the pin rotation and specimen translation were manually stopped to produce a pinfrozen into the workpiece.Plan view and transverse metallographic sections were examinedafter etching.Based on the microstructural examinations,Guerra et al.[31]concluded that thematerial was moved around the pin in FSW by two processes.First,material on the advancing sidefront of a weld entered into a zone that rotates and advances simultaneously with the pin.Thematerial in this zone was very highly deformed and sloughed off behind the pin in arc shaped features.This zone exhibited high Vicker’s microhardness of95.Second,material on the retreatingfront side of the pin extruded between the rotational zone and the parent metal and in the wake ofthe weldﬁlls in between material sloughed off from the rotational zone.This zone exhibited lowVicker’s microhardness of35.Further,they pointed out that material near the top of the weld (approximately the upper one-third)moved under the inﬂuence of the shoulder rather than thethreads on the pin.Colligan[32,33]studied the materialﬂow behavior during FSW of aluminum alloys by means ofsteel shot tracer technique and‘‘stop action’’technique.For the steel shot tracer technique,a line ofsmall steel balls of0.38mm diameter were embedded along welding direction at different positionswithin butt joint welds of6061Al-T6and7075Al-T6plates.After stopping welding,each weld was subsequently radiographed to reveal the distribution of the tracer material around and behind the pin.The‘‘stop action’’technique involved terminating friction stir welding by suddenly stopping theforward motion of the welding tool and simultaneously retracting the tool at a rate that caused thewelding tool pin to unscrew itself from the weld,leaving the material within the threads of the pinintact and still attached to the keyhole.By sectioning the keyhole,theﬂow pattern of material in theregion immediately within the threads of the welding tool was revealed.These investigations revealedthe following important observations.First,the distribution of the tracer steel shots can be divided intotwo general categories:chaotical and continuous distribution.In the regions near top surface of theweld,individual tracer elements were scattered in an erratic way within a relatively broad zone behindthe welding tool pin,i.e.,chaotical distribution.The chaotically deposited tracer steel shots had movedto a greater depth from their original position.In other regions of the weld,the initial continuous line ofsteel shots was reorientated and deposited as a roughly continuous line of steel shot behind the pin,i.e., continuous distribution.However,the tracer steel shots were found to be little closer to the uppersurface of the weld.Second,in the leading side of the keyhole,the thread form gradually developedfrom curls of aluminum.The continuous downward motion of the thread relative to the forwardadvance of the pin caused the material captured inside the thread space to be deposited behind the pin.Based on these observations,Colligan[32,33]concluded that not all the material in the tool path wasactually stirred and rather a large amount of the material was simply extruded around the retreatingside of the welding tool pin and deposited behind.However,it should be pointed out that if the marker10R.S.Mishra,Z.Y.Ma/Materials Science and Engineering R50(2005)1–78 material has differentﬂow strength and density,it can create uncertainty about the accuracy of theconclusions.London et al.[34]investigated materialﬂow in FSW of7050Al-T7451monitored with6061Al–30vol.%SiC p and Al–20vol.%W composite markers.The markers with a cross-section of0.79mmÂ0.51mm were placed at the center on the midplane of the workpiece(MC)and at theadvancing side on the midplane(MA).In each FSW experiment,the forward progress of the tool wasstopped while in the process of spreading the marker.The distribution of marker material wasexamined by metallography and X-ray.Based on experimental observations,London et al.[34]suggested that theﬂow of the marker in the FSW zone goes through the following sequence of events.First,material ahead of the pin is signiﬁcantly uplifted because of the38tilt of the tool,which creates a‘‘plowing action’’of the metal ahead of the weld.Second,following this uplift,the marker is shearedaround the periphery of the pin while at the same time it is being pushed downward in the plate becauseof the action of the threads.Third,marker material is dropped off behind the pin in‘‘streaks’’whichcorrespond to the geometry of the threads and speciﬁc weld parameters used to create these welds.Furthermore,London et al.[34]showed that the amount of material deformation in the FSW welddepends on the locations relative to the pin.Markers on the advancing side of the weld are distributedover a much wider region in the wake of the weld than markers that begin at the weld centerline.3.1.1.2.Flow visualization by FSW of dissimilar materials.In addition to the tracer technique,several studies have used friction stir welding of dissimilar metals for visualizing the complexﬂowphenomenon.Midling[35]investigated the inﬂuence of the welding speed on the materialﬂow inwelds of dissimilar aluminum alloys.He was theﬁrst to report on interface shapes using images of themicrostructure.However,information onﬂow visualization was limited to the interface betweendissimilar alloys.Ouyang and Kovacevic[36]examined the materialﬂow behavior in friction stir butting welding of2024Al to6061Al plates of12.7mm thick.Three different regions were revealed in the weldedzone.Theﬁrst was the mechanically mixed region characterized by the relatively uniformly dispersedparticles of different alloy constituents.The second was the stirring-induced plasticﬂow regionconsisting of alternative vortex-like lamellae of the two aluminum alloys.The third was the unmixedregion consisting ofﬁne equiaxed grains of the6061Al alloy.They reported that in the welds thecontact between different layers is intimate,but the mixing is far from complete.However,the bondingbetween the two aluminum alloys was complete.Further,they attributed the vortex-like structure andalternative lamellae to the stirring action of the threaded tool,in situ extrusion,and traverse motionalong the welding direction.Murr and co-workers[8,10,37,38]investigated the solid-stateﬂow visualization in friction stir butt welding of2024Al to6061Al and copper to6061Al.The materialﬂow was described as achaotic–dynamic intercalation microstructures consisting of vortex-like and swirl features.Theyfurther suggested that the complex mixing and intercalation of dissimilar metals in FSW is essentiallythe same as the microstructures characteristic of mechanically alloyed systems.On the other hand,arecent investigation on friction stir lap welding of2195Al to6061Al revealed that there is large verticalmovement of material within the rotational zone caused by the wash and backwash of the threads[31].Guerra et al.[31]have stated that material entering this zone followed an unwound helical trajectoryformed by the rotational motion,the verticalﬂow,and the translational motion of the pin.3.1.1.3.Microstructural observations.The idea that the FSW is likened to an extrusion process isalso supported by Krishnan[39].Krishnan[39]investigated the formation of onion rings in friction stirwelds of6061Al and7075Al alloys by using different FSW parameters.Onion rings found in the。

超声波技术在肉品加工中的应用研究进展

黄荣秋，臧明伍，李海花，等. 超声波技术在肉品加工中的应用研究进展[J]. 食品工业科技，2023，44（20）：431−439. doi:10.13386/j.issn1002-0306.2022100228HUANG Rongqiu, ZANG Mingwu, LI Haihua, et al. Research Advance of Application of Ultrasonic Treatment in Meat Processing[J].Science and Technology of Food Industry, 2023, 44(20): 431−439. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022100228· 专题综述 ·超声波技术在肉品加工中的应用研究进展黄荣秋1,2，臧明伍1, *，李海花2，柴　悦1,2，赵　冰1，张顺亮1，张哲奇1，张凯华1，李　素1，吴倩蓉1，李　丹1（1.中国肉类食品综合研究中心北京食品科学研究院，北京 100068；2.天津农学院动物科学与动物医学院天津市农业动物繁育与健康养殖重点实验室，天津 300384）摘　要：目前，超声波处理在肉品加工前处理及热加工中得到广泛的研究和应用，研究普遍认为超声波的空化效应、机械效应和热效应是引起肉品品质改变的主要原因。

本文综述了超声波技术在肉品加工中的技术原理及其在肉品加工前处理和热加工过程中的应用进展，阐述了超声波辅助加工过程中对肉类嫩度、色泽、保水性及脂质、蛋白质氧化的改善效果，并对其应用前景进行展望。

总体而言，超声波技术在辅助冻结、解冻、腌制、热加工中对肉类理化性质及感官品质具有显著改善作用。

本文为超声波技术在肉品加工中的应用提供了理论参考。

关键词：超声波，原理，应用，前处理，热加工，肉类品质本文网刊:中图分类号：TS251.4 文献标识码：A 文章编号：1002−0306（2023）20−0431−09DOI: 10.13386/j.issn1002-0306.2022100228Research Advance of Application of Ultrasonic Treatment in MeatProcessingHUANG Rongqiu 1,2，ZANG Mingwu 1, *，LI Haihua 2，CHAI Yue 1,2，ZHAO Bing 1，ZHANG Shunliang 1，ZHANG Zheqi 1，ZHANG Kaihua 1，LI Su 1，WU Qianrong 1，LI Dan 1（1.China Meat Research Center, Beijing Academy of Food Science Center for Food Evaluation, Beijing 100068, China ；2.Tianjin Key Laboratory of Agricultural Animal Breeding and Healthy Husbandry, College of Animal Science andVeterinary Medicine, Tianjin Agricultural University, Tianjin 300384, China ）Abstract ：Ultrasonic treatment has been widely researched and applied in the pre-processing and thermal processing of meat and meat processed products at present. The cavitation effect, mechanical effect, and thermal effect of ultrasonic wave are considered to be the main reasons for the changes of meat quality. In this paper, the basic principle of ultrasound and the application progress in pre-treatment and thermal processing in meat processing are reviewed. The effects of ultrasonic treatment on meat tenderness, color, water holding capacity, and lipid and protein oxidation are summarized. The future prospect of its application is also proposed. In general, the physicochemical property and sensory quality of meat and meat processed products are significantly improved during ultrasound-assisted freezing, thawing, curing, and thermal processing.The paper provides a theoretical reference for the application of ultrasonic treatment in meat processing.Key words ：ultrasonic wave ；principle ；application ；pre-treatment ；thermal processing ；meat quality超声波是由声波传播过程中介质分子运动产生的机械波组成，传播频率高，不能被人耳察觉[1]，广泛应用于化工、医药、农业等领域[2−5]。

It has the task to spray suitabale adhesive on the rectilinear and continuous rubber profile

It has the task to spray suitabale adhesive on the rectilinear and continuous rubber profile , which is running inside the cabin itself right through, by slits; cylindrical rolls built in frictions and consequent stretching to the profile itself.The adhesive, contained into extractable tanks for reloading, is transferred to the spraying guns by using the compressed air drawn from the factory plant.The guns, automatic type, can be connected and disconnected together with the line or completely or partially excluded by manaul intervention.They are mounted on vertical bars with articulated joints, in order to obtain a proper orientation toward the profile.Further adjustments can be obtained by operating on guns nozzles, in order to change the jet capacity and width.Controls are placed in the upper structure front together with gauges and pressure regulator. Above the cabin is placed a suction unit consisting of one motor with fan, in order to draw the vapours produced during spraying.Such vapours are previously passing through one filtering unit, accessible from the replacement from a convenient back scuttle.The cabin foresees also an automatic fire-fighting device, placed up the profile and in a central position;it is driven in case of fire from a bulb breaking calibrated to withstand up to 68℃。

电子产业联盟开发的IPC-1752A Class D标准关于有害物质限制的全物料申报文件说明书

Full Material Declarations: Removing Barriers to Environmental Data ReportingRoger L. FranzTE ConnectivityMiddletown, PA USAAbstractSince the European Directives, RoHS (Restriction of Hazardous Substances) and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), entered into force in 2006-7, the number of regulated substances continues to grow. REACH adds new substances roughly twice a year, and more substances will be added to RoHS in 2019. While these open-ended regulations represent an ongoing burden for supply chain reporting, some ability to remain ahead of new substance restrictions can be achieved through full material declarations (FMD) specifically the IPC-1752A Class D Standard (the “Standard”), which was developed by the IPC - Association Connecting Electronic Industries. What is important to the supply chain is access to user-friendly, easily accessible or free, fully supported tools that allow suppliers to create and modify XML (Extensible Markup Language) files as specified in the Standard. Some tools will provide enhancements that validate required data entry and provide real-time interactive messages to facilitate the resolution of errors. In addition, validation and auto-population of substance CAS (Chemical Abstract Service) numbers, and Class D weight rollup validation ensure greater success in the acceptance of the declarations in customer systems that automate data gathering and reporting.A good tool should support importing existing IPC-1752A files for editing; this capability reduces the effort to update older declarations and greatly benefits suppliers of a family of products with similar composition. One of the problems with FMDs is the use of “wildcard” non-CAS numbers based on a declarable substance list (DSL). While the substances in different company’s lists tend to have some overlap, no two DSL’s are the same. We provide an understanding of the commonality and differences between representative DSLs, and the ability to configure how much of a non-DSL substance percent is allowed. Case studies are discussed to show how supplier compliance data, can be automatically loaded into the customer’s enterprise compliance system. Finally, we briefly discuss future enhancements and other developments like Once an Article, Always an Article (O5A) that will continue to require IPC standards and supporting tools to evolve.IntroductionFull material declaration of product content in electronics and other industries continues to be a challenge for both suppliers and customers alike. For suppliers, managing substance-level data for all the materials in products is not usually a part of normal business operations, but rather, is an added burden and therefore cost to doing business. Customers, from mid-supply chain enterprises to OEM’s, must have processes and systems to request, manage, and utilize the data to ensure compliance with worldwide substance regulations. These issues call out for easy to use software solution to aid reporting.The IPC-1752A Materials Declaration Management Standard (/1752) which is aligned with IPC-1751A Generic Requirements for Declaration Process Management (/1751) is widely used for environmental reporting today. The standard specifies an XML (Extensible Markup Language) schema for mandatory and required data, including support for Class D FMD’s for homogenous materials and substances required by the RoHS Directive (the full citation for the current “RoHS Recast” legislation is “Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011 on the restriction of the use of certain hazardous substances in electrical and electronic equipment.”)In this paper, we focus on requirements for tools that enable rapid and accurate reporting of Class D FMD’s that can be used by suppliers primarily in the base of the supply chain, e.g. raw materials and smaller components. We also provide examples of how this data can be used by the supplier’s immediate customer to build more complex FMD data for product-level assemblies.Why Take the Road to FMD?One of the advantages of the FMD approach is that it is the only way a company can stay ahead of the ongoing addition of regulated substances. RoHS has been relatively static in this regard -- with only changes being to allowable Exemptions and additional documentation requirements. Otherwise, the basic 6 restricted substance have stayed the same from its initial entry into force through its “Recast”in 2011. The next addition of four additional substances, per the European Commissions Delegated Directive 2015/863/EU, will enter into force July 22, 2019. However, customers across the supply chain are already asking for data and compliance conclusions for these substances. This pre-enactment customer driven activity clearly demonstrates just how valuable FMD’s can be since suppliers with FMD data can already satisfy their customer’s requests about the presence of newly (and yet-to-be) restricted substances.Since RoHS exemptions have set expiration dates, it is also prudent to know what exempted substance is present, besides just knowing you are Compliant with Exemption but not exactly why. Since exemptions are substance-specific, this level of information is very useful as a warning that a noncompliance could develop when a product that was once acceptable to ship is no longer compliant because the exemption has expired! FMD data provides the ability to look ahead in time for exemptions that are set to expire, allowing the company to take early action through product redesign or finding alternate suppliers.REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), promulgated by a separate agency, ECHA, (European Chemicals Agency), is much more dynamic and adds new Substances of Very High Concern (SVHC) to the Candidate list roughly twice a year ever since 2008. Figure 1 shows the number of substances added to REACH since its beginning in Oct., 2008 through the last date as of this writing. Shorter gray bars count the substances added each date, with the larger black bars indicating the cumulative total of substances.Figure 1 – Number of REACH SVHCs from 2008-PresentNote that there is some double counting in the Figure 1 data, since a few of the substances were listed a second time due to different toxicological reasons. Also, note that the count is based on just the primary list of SVHC posted by ECHA in its main table (https://echa.europa.eu/candidate-list-table) but the actual individual substance count by CAS number is even greater if one consults the ECHA supporting documentation. Further, it is noted that Amendment 3 of IPC-1752A, which is not fully published as of the time of this writing, will contain a non-exhaustive list of substances and their CAS numbers as a convenient reference to this ever-growing list of substances.Useful information about the Standard and its implementation and advantages may be found on the IPC web page “Data Exchange Standards” (/ContentPage.aspx?pageid=Materials-Declaration). Additional advantages of FMD have been published, for example, by companies offering such services, companies nee ding FMD’s from their suppliers, industry conferences, and articles in electronics journals (1, 2).The story continues and the message remains clear: companies need a way to stay ahead of the growing list of new substances they are required to manage. FMD’s are the best way to do so.Requirements Part One – The Schema is the RoadbedIn the next sections, we list and explain the value of functional requirements that a good, basic FMD reporting tool should have. At the most basic level, the tool by its nature will be software, and to be used for reporting up the supply chain the XML declaration file must conform to the IPC Standard itself. In recent years, the chairs and participants in the IPC 2-18b Materials Declaration Task Group have graciously offered their time and expertise to help review, on a blind submission basis, XML files including Class D FMD’s. Using software tools that are available for checking conformance to the schema as specified in the Standard, as well as a review by IPC 2-18b participants, those software solution providers that have beenverified in this review process and found to conform to the schema in their test files are listed by IPC (also at /ContentPage.aspx?pageid=Materials-Declaration.)As the relatively recent history of the IPC review process shows in Table 1, a handful of solution providers have supported and continue to support Class D FMD’s, as well as the other reporting classes A and C (not shown). It may be concluded that there are enough competent software solution providers to offer a choice, yet not be overwhelming for companies just embarking on the journey to generate FMD’s. Specific company names can be found on the IPC web site as cited above.Some of the basic requirements for conformance to the standard schema include the following:•All mandatory data elements (tags) are present, which must be completed when entering data into the tool, if not already present from some prior data entry or load. These elements include data like supplier and customer ID’s and part numbers, and homogenous materials in the product broken down by substances and their weights.•Ability to enter the most useful optional data elements as desired, or as requested by the customer. For example, substance weight is mandatory, but concentration is optional.•Ability to incorporate a legal statement, either with a standard boilerplate or by entering a custom statement.•Tags identifying the data as Class D (FMD) based on substance reporting at the homogeneous material level; class C substance category reporting at the product level; or Class A Query/Reply format (true/false compliance statements).•Further details including a complete list of Mandatory and Optional data may be found in the IPC-1752A standard. Requirements Part Two – Lanes of Chemical DataSince FMD is all about the chemical data, and suppliers in the electronics industry may not have extensive chemical expertise, this set of functionality is critical to generating Class D XMLs as correct and error-free as possible. Clearly, to even begin generating FMDs requires having the product’s chemical composition data, and unfortunately there is no magic to manage this complexity other than a materials and substances database or spreadsheets to manage the list of ingredients to be reported. Some of the major CAD systems are offering functionality to select raw materials from a database coupled to the CAD system, which is logical since the designer is specifying the materials in the first place. More about how to develop basic “what’s in the product” documentation may be a good topic for another report, since by some accounts this is still the greatest obstacle to begin any FMD.Next, we briefly highlight important functional requirements for any tool used to generate FMDs from materials and substance data.Ability to select substances from a list by CAS number prevents errors, since CAS number is a key for many receiving systems and is the Authority tag specified in the IPC standard. A CAS number lookup list should be provided in the tool, which has the advantage of speeding up data entry and selecting matches quickly from valid selections provided by the tool. The tool may also validate the format of the CAS number format itself, which must be 10 digits separated into 3 groups by hyphens, with the last digit being a check digit. These rules are published by CAS (https:///content/chemical-substances/checkdig). This type of validation may be useful to allow newer, valid CAS numbers that are not in the lookup table to still be entered. The problem of “wildcard” or declarable/reportable substance lists will be covered in the next section, since it remains a problem in the industry.A lookup of substance names can also expedite entering substances data, again by ensuring that a valid substance name is used and a valid CAS number goes along with it. The advantage is that a substance name may be more easily recognized and used by a human than a CAS number. This approach to validation has the disadvantage that compounds and even pure elements may have many different synonyms, in which case the direct CAS number lookup would be more useful.The input screen for materials and substances data may look something like Figure 2. This kind of table is the heart of a FMD, where each Material is composed of its constituent Substances, all with reported weights in the product. Optionally, data like attachment files and concentration ranges may be accommodated. If Exemptions apply at the Material level, they may also be selected.Figure 2. Example of Material and Substance Input Screen (3)Direct entry into a reporting tool is likely to be of interest to suppliers making raw materials or simple components, rather than OEM’s. But this data becomes the basis of creating FMD’s for more complex products. S uppliers of the following kinds of items might be in the best position to take advantage of the kinds of tools being discussed here.o Solder and solder flux (separately or in paste or wire)o Bulk material like sheets, or parts made of a homogenous materialo Metal alloys, or parts made from themo Wireo Mold compound; molded partso Underfillo Conformal coatingo Plating, painted or dipped coating, or other types of coatingo Adhesives, lubricants or sealantsFMD’s for these items can allow the next tier customer to use it for reporting at the next assembly level. Companies on the more complex end of the supply chain may need to use larger enterprise systems to collect this data and run final reports, so the more basic FMD generating tools may be of less interest to them. Figure 3 shows how the data cascade works. As originally envisioned with the first release of IPC-1752 in 2006, the data cascade is still deserving of more widespread understanding and more thorough implementation today. We realize the complexity of electronic products, since even small personal use devices may contain hundreds to thousands of components, the key point here is that having good tools at the very beginning stage can be useful as the data builds in complexity up to reports for more complex products.Figure 3. Cascade of FMD DataRequirements Part Three – The Wildcard DetourBy necessity, companies and standards organizations themselves have used Reportable or Declarable Substances Lists (DSL) for years. One of the early lists was the Joint Industry Guide (JIG) which went through several updates. Amendment 3 to IPC-1752A includes the following statement: The IEC 62474 database of restricted and declarable substances replaced the Joint Industry Guide (JIG) in January 2014.Meanwhile, most companies have created their own DSLs so that they will receive:o Data on those substances currently with regulatory restrictionso Data on industry-specific substanceso Data on other substances the company’s customers expect to know abouto Substances that are not yet under any regulatory restrictions, but could be at some future date.This latter case is exactly the REACH situation shown at the beginning of this paper. While there are some ways to get advanced information about the next substances to be added to REACH, these are not usually foolproof. Therefore, companies tend to cast a rather wide net to ensure future substanc es are being included in their suppliers’ declarations.The IEC62474 database (http://std.iec.ch/iec62474) as of this writing was most recently revised on Sept. 3, 2017, and contains 137 Declarable substances and 482 Reference substances. Many companies have nonetheless found it necessary, for the reasons listed above, to develop more comprehensive lists of their own. Without mentioning specific company DLS’s here, a general review of some of the many that are used in the electronics industry shows two basic trends: o Substances listed in common as a core set of substances, including those in common with the IEC62474 listo Substances that are less frequently found and not part of a common core listSince homogeneous material reporting is at the substance level, with authority being the CAS number, this presents a data handling/segregation dilemma.In a good reporting tool, then, some accommodation must be made for accepting these “wildcard” substances which inherently have no CAS number. We have seen a commonly but not universally accepted limit of 10% per homogenous material can be checked in the tool to ensure this limit is not exceeded. A good tool should also allow for a choice of a customer-specific wildcard substance name, which is not subject to checking from a CAS number list or a CAS format validation routine. Based on our review, if proper warnings are provided, this appears to be the best way at present to handle such data.Requirements Part Four – Fewer Barriers, More Open RoadSo far, we have presented desirable features to help generate FMD’s. The real power, though, is only realized through ability to revise, reuse, and build on data once it has been initially entered into a tool.First of these capabilities is ability to quickly edit the substances in a material. For companies making a family of items with related composition, changing just a few entries, or modifying the percentages of them, can be done in seconds and saved under a different product name and XML file, with version tracking as desired in the file name. This should be allowed during an existing session, or combined with the next feature.Once a complete XML FMD is generated, productivity is enhanced if that file can be easily imported again at a later date and edited as required. This portability and flexibility of data allows a supplier further down the supply chain to utilize a growing library of common materials and their formulations, and to quickly create new ones without having to repeat some or even most of the data entry. In most cases, the company’s own information, like company ID, contact and authorizer, will be repeated over many declarations. If contact and authorizer are the same person, they could be copied directly with a choice in the tool.While we are focusing here on the Class D FMD, ability to generate Class A or Class D declarations at the same time may be useful. These should be selected, or de-selected as desired, or as required by the customer. Class A query/response answers should be straightforward, as should selection of exemptions from a list. Similarly, the substance data in the Class D data section should be quickly erased to enter fresh data while retaining the rest of the information already entered.Interactive helps should provide guidance to first time and infrequent users. Checks along the way improve speed and accuracy without having to consult a user’s manual, which incidentally should also be easily accessible for those who wish to read the instructions first. Finally, the tool should prevent hang-ups and errors. Support services should be provided, and a process to investigate and resolve bugs, or perceived bugs, should be easy to submit and provide timely responses.At the end of data entry there should be a final validation of the XML, included mandatory information has been entered and the weights of substances add up to each homogenous material being reported. These checks help ensure that the XML will successfully load to the customer’s system.Conclusions - To the SuperhighwayAccording to some observers, FMD still has too many barriers to really catch on. We disagree. Supply chain reporting has to begin somewhere, by providing data to middle supply chain companies, and so forth up to chain to the OEM. FMD is the only reporting approach that helps to minimize the ongoing burden of keeping up with the ever-growing lists of regulated substances and expiring exemptions.We have mentioned that the IEC 62474 database is now invoked as the reportable substance list in IPC-1752A Amendment 3. In addition, development of an IEC 62474 international standard for reporting is in process, which will also specify anXML format. Work is underway to harmonize the schema of both IPC and IEC standards via communication and common participants in both IPC and IEC standards development, but differences should still be expected. Development of the IEC reporting standard nevertheless underscores the interest and need for FMD realization in XML format.Further enhancements can also be realized in the future; to name a few:•Integration with manufacturing data for mixed, compounded or formulated materials•Availability of integrated materials selection with design tools for more complex products•True Business-to-Business methods to request data as well as provide data all in standard machine-readable formats •Enhanced error checking, validation of common-sense rules, and agreement between, for example, a Class A declaration that says RoHS Compliant = True, yet the Class D file for the same item reports a RoHS substance over the threshold percent.•Support for updated guidance from ECHA on Once an Article, Always and Article, which changes substance percent reporting from any top-level assembly to the lowest level Article exceeding the 0.1% SVHC threshold. It is becoming clear that this will require a new data attribute to flag Articles, as distinct from unshaped Materials or Complex Objects. It is our understanding that this will be considered in the development of a revised IPC-1752B Standard.In addition to the motivation of staying ahead of the growing number of regulated substances, a business processes and procedures that support FMD can also be useful. The expectation that FMDs must be provided can be a requirement for gaining new business or for qualification of an item as a prerequisite to be purchased. A company can also include FMD responsiveness in ongoing supplier evaluation performance ratings that may influence awarding future business. Once an FMD is received in well-formed XML format, loading this data to the customer’s system can be automated for maximum efficiency and reused through the FMD cascade process. We have seen it work and only need more FMDs entering the road. References1. M. Myles, “Supply Chain Data Exchange for Material Disclosure.”Journal of Surface Mount Technology, Vol. 19-1, 2006. https:///knowledge/journal detail.cfm?ARTICLE ID=1232. R. Franz, “Beyond “Lead-Free”: An Update on the IPC-1752A Standard for Materials Declaration.” Electronics Design, Jan. 8, 2015. /components/beyond-lead-free-update-ipc-1752a-standard-materials-declaration3. https:///fmdcomplete/ © 2017 Assent Compliance Inc.IntroductionA customer emails you and says,“Please provide your FMD’s for this list of parts”Your reaction?IPC Standardso IPC-1752A Materials Declaration Management Standardo IPC-1751A Generic Requirements for Declaration Process Managemento Both specify XML (Extensible Markup Language) machine-readable formato IPC-1752A Class D supports FMD with Homogenous Materials and Substances IEC 62474 also under revision for better harmonization with IPC-1752 XML format Good tools are needed to generate FMD XML at the beginning of the supply chainEnd of presentation… but not “The End.”Thank you for your attention : )AcknowledgementThe dedication, innovation and ongoing work of the IPC 2-18b Materials Declaration Task Group is gratefully appreciated –including founding members, current members, chairpersons, andfuture users of IPC-1752.[1]https:///fmdcomplete/ © 2017 Assent Compliance Inc.。

2023年英语四级听力真题(第一套)题目,原文与答案

2023年6月英语四级听力真题（第一套）Questions 1 and 2 are based on the news report you have just heard.1. A) She was involved in a conflict with bird lovers.B) She was charged with mistreating animals.C) She was on bad terms with her neighbors.D) She was accused of violating a city law.2. A) It will take time to solve the rat problem.B) All wild animals should be well protected.C) The woman was not to blame for the situation.D) No one should go unpunished for violating law.Questions 3 and 4 are based on the news report you have just heard.3. A) Communicate with astronauts in Mars Dune Alpha.B) Work in an environment resembling Mars.C) Build a Martian habitat in Houston.D) Send in applications before Friday.4. A) Ready-made food.B) Food that is organic.C) Food they grow.D) Potatoes mostly.Questions 5 to 7 are based on the news report you have just heard.5. A) He apologized for scratching an athlete’s gold medal.B) He was asked to present a gold medal to Miu Goto.C) He bit a softball player’s Olympic gold medal.D) He attracted public attention at a media event.6. A) Have another picture taken with the Olympic medalist.B) Apologize to the International Olympic Committee.C) Get the damaged medal repaired.D) Pay for the cost of a new medal.7. A) Allow no one to touch them.B) See them as symbols of honor.C) Treat them as treasures.D) Keep them in a safe place.Questions 8 to 11 are based on the conversation you have just heard.8. A) She covered its screen with a plastic sheet.B) She connected it with her smart phone.C) She decorated it with colorful stickers.D) She bought some new software for it.9. A) It may not be simply blue.B) It includes unnatural light.C) It is more harmful to young people.D) It induces people to fall asleep.10. A) He has had much trouble falling asleep.B) He has had some sort of health problems.C) He has stayed up playing computer games.D) He has been burdened with excessive work.11. A) Exposure to blue light is the chief cause of obesity.B) Sleep may be more important than people assumed.C) Sleep may also be negatively affected by natural light.D) Overuse of electronic devices may cause heart disease.Questions 12 to 15 are based on the conversation you have just heard.12. A) What they wanted to be when grown up.B) What their favorite cartoon character was.C) What they learned from computer games.D) What they liked to do most after school.13. A) A stock broker.B) A pop singer.C) A mechanical engineer.D) A basketball player.14. A) Ambitious.B) Sensible.C) Imaginative.D)Practical.15. A) Relax their strict control of their kids.B) Help their kids understand themselves.C) Impose their own dreams on their kids.D) Dismiss their high expectations of their kids.Questions 16 to 18 are based on the passage you have just heard.16. A) Set up company branches.B) Improve its infrastructure.C) Introduce iPhones into its markets.D) Promote Internet-ready phones.17. A) They cater to Africans’ needs.B) They are more expensive models.C) They are more powerful and capable.D) They boast the longest battery life.18. A) A large touchscreen.B) An old-school keypad.C) A voice-response device.D) A digitally-designed system.Questions 19 to 21 are based on the passage you have just heard.19. A) It ensured sustainable economic growth.B) It was strongly opposed by manufacturers.C) It was cheaper than using fossil fuel plastic.D) It satisfied consumer demands on the whole.20. A) The capacity to mass produce it.B) The U.S. federal government’s regulations.C) A boom in market demand for clear plastic bottles.D) A rapid increase in U.S. petroleum chemical production.21. A) Require companies to use 30% of new plastic.B) Increase the supply of new plastic in the market.C) Reduce the amount of plastic pollution in local areas.D) Take measures to promote the use of recycled plastic. Questions 22 to 25 are based on the passage you have just heard.22. A) It studies dreams.B) It rents a place for nap-takers.C) It is a hotel for business people.D) It is a nap research institute.23. A) To find out creative people’s work performance.B) To see how many people can go without napping.C) To understand the obvious importance of napping.D) To feel how difficult it is to get his idea across.24. A) They decline due to pointless meetings.B) They depend on his ability to concentrate.C) They enable him to enjoy a creative career.D) They are affected by the overuse of social media.25. A) Some bosses associate napping with laziness.B) Many office workers nap during work hours.C) Some bosses can concentrate without napping.D) Many of his friends daydream in the office.答案速查1. D) She was accused of violating a city law.2. A) It will take time to solve the rat problem.3. B) Work in an environment resembling Mars.4. A) Ready-made food.5. C) He bit a softball player’s Olympic gold medal.6. D) Pay for the cost of a new medal.7. C) Treat them as treasures.8. A) She covered its screen with a plastic sheet.9. B) It includes unnatural light.10. D) He has been burdened with excessive work.11. B) Sleep may be more important than people assumed.12. A) What they wanted to be when grown up.13. C) A mechanical engineer.14. C) Imaginative.15. B) Help their kids understand themselves.16. D) Promote Internet-ready phones.17. A) They cater to Africans’ needs.18. B) An old-school keypad.19. C) It was cheaper than using fossil fuel plastic.20. D) A rapid increase in U.S. petroleum chemical production.21. D) Take measures to promote the use of recycled plastic.22. B) It rents a place for nap-takers.23. C) To understand the obvious importance of napping.24. B) They depend on his ability to concentrate.25. A) Some bosses associate napping with laziness.听力原文与答案Section ANews Report One(1) A woman was charged with allegedly violating a Rhode Island city law against feeding wild animals. The 55-year-old woman’s neighbors blame her for making the area’s rat problem worse. Newly installed cameras captured several rats active in the middle of the day. Neighbors say that it’s even worse during the night. The woman and her parents, who owned the home, told reporters that she’s being charged for feeding birds.“W ho would have known just loving animals gets you that much trouble,” she said.It is prohibited to feed any wild animals, including birds, in Rhode Island city. Nevertheless, while the woman’s intention was to feed birds, it is clear that rats were also benefiting.(2) Anthony Moretti, director of the city administration, said he saw more than 20 rats near the woman’s home. He said it will take months to get the problem under control.Questions 1 and 2 are based on the news report you have just heard.Q1. What do we learn from the report about the 55-year-old woman? 答案: D)Q2. What did the director of the city administration say at the end of the news report? 答案: A)News Report TwoTo prepare for eventually sending astronauts to Mars, NASA began taking applications Friday for four people to live for a year in Mars Dune Alpha. That’s a 1,700-square-foot Martian habitat inside a building in Houston.(3) The paid volunteers will work in an environment similar to Mars. They will have limited communications with family, restricted food and resources.NASA is planning three experiments with the first one starting in the fall next year. (4) Food will all be ready-to-eat space food. Some plants will be grown, but not potatoes like in the movie “The Martian”.“We want to understand how humans perform in them,” said lead scientists Grace Douglas. “We are looking at Mars realistic situations.”The application process opened Friday and they’re not seeking just anybody. The requirements are strict, including a master’s degree in a science, engineering or math field or pilot experience. Only American citizens or permanent U.S. residents are acceptable. Applicants must be between 30 and 55 and in good physical health.Attitude is key, said former Canadian astronaut Chris Hadfield. He said the participants need to be super competent, resourceful, and not relying on other people to feel comfortable.Questions 3 and 4 are based on the news report you have just heard.Q3. What does NASA require the paid volunteers to do? 答案: B)Q4. What will the participants in the project eat? 答案: A)News Report Three(5) A Japanese mayor apologized Thursday for biting the Olympic gold medal of a softball player. Nagoya mayor Takashi Kawamura had praised athlete Miu Goto during a public media event. He asked her to put the medal around his neck. Kawamura then bit into it.Biting a medal in front of journalists and photographers has become a common pose for Olympic medalists. However, it is only for the winners themselves, not others.“I’m really sorry that I hurt the treasure of the gold medalist,” Kawamura told reporters Thursday. (6) The mayor said the medal was undamaged, though he offered to pay for the cost of a new one. Goto, however, has accepted the International Olympic Committee’s offer of a replacement, according to Japanese media reports.The scene broadcast on television prompted thousands of complaints to city hall. (7) Some Olympians said they treat their medals as treasures and that it was disrespectful and unacceptable for Kawamura to bite one.“I would cry if that happened to me,” s aid another athlete,Naohisa Takato. “I handle my own gold medal so gently that I would not scratch it.”Questions 5 to 7 are based on the news report you have just heard.Q5. What does the news report say about the Japanese mayor Takashi Kawamura? 答案: C)Q6. What did Mayor Takashi Kawamura offer to do? 答案: D)Q7. What did some Olympians say they would do with their medals? 答案: C)Section BConversation OneM: (8-1) What’s that orange thing on your computer screen?W: It’s something I bought yesterday. (8-2) It’s a plastic sheet that blocks blue light. I have one that I use to cover my phone screen too.M: What do you mean by blue light?W: (9) Blue light includes natural light, but it also includes light that isn’t natural. For example, from computers, phones, televisions, and other electronic devices.M: So, blue light is harmful and that’s why you want to block it?W: It isn’t that simple. Blue light isn’t necessarily bad for us. In fact, we need blue light during the day to be healthy, but too much blue light, especially from electronic devices, can harm our health by weakening our vision and making it harder for us to fall asleep. And poor sleep can cause all sorts of health problems.M:I’m not so sure that sleep is nearly as important as people always say it is. (10) I haven’t slept enough in months because I have too much work to do and I feel fine, and it’s the same for most of my friends. Poor sleep might be a problem for old people, but surely young people can handle late nights. W: Well, (11) the research I’ve read shows that sleep is probably even more important than we thought, and that not having enough sleep can contribute to serious health problems like obesity and heart disease. And all the artificial blue light from electronic devices means we have to try harder to sleep well.M: Maybe you’re right. I’m on my computer very late most nights, and that’s probably why I don’t sleep enough.Questions 8 to 11 are based on the conversation you have just heard.Q8. What did the woman do to her computer? 答案: A)Q9. What does the woman say about blue light? 答案: B)Q10. Why does the man say he hasn’t slept enough for months? 答案: D)Q11. What has the woman learned from the research she has read? 答案: B)Conversation TwoW: As a kid did you know what job you wanted to do when you grew up?M: No, I didn’t. (12-1) And I got sick every time adults asked me what I wanted to be when I grew up. W:(12-2) It’s the same with me. And I’m tired of people asking that question of my 10-year-old daughter. (13) My daughter’s stock answers are basketball player, pop singer, mechanical engineer. Adults love that last one as it’s the perfect mix of the sensible and the ambitious. When she was much younger, my daughter used to say she wanted to be queen of the clouds, which I loved. (14) That’s the kind of goal setting I like to see in children, springing from their boundless imaginations.M: Yes, we grown-ups can be tedious and limiting in our need for reality. And we teach a very gloomy image of adulthood that whatever our children’s future holds, it must be seen within the context of a job.W: How utterly overwhelming and dull!M: When people ask my son what he wants to be when he grows up, I have to swallow the urge to say, “Hey, back off my kid’s dreams.”W: We can’t dismiss the idea that teenagers have to plan to do something after they finish school, and parents are entitled to hope it’s more than simply spending 10 hours a day playing computer games. M: But asking, “What do you want to be?” i sn’t going to lead a child to a fulfilled life, rather, leads to false expectations and a high chance of disappointment.W: Exactly. (15) We should be helping our kids understand who they are, even if that means letting go of who we think they should be.Questions 12 to 15 are based on the conversation you have just heard.Q12. What question were both speakers fed up with when they were kids? 答案: A)Q13. What occupation do adults see as both sensible and ambitious according to the woman? 答案: C) Q14. What kind of goal setting does the woman like to see in children? 答案: C)Q15. What does the woman suggest adults should do? 答案: B)Section CPassage OneGreater Internet access correlates directly with improved healthcare, education and economic development. People living in rural areas, however, lag behind in online use, which limits their access to government services, banking, and job opportunities. Nowhere is this challenge clearer than in Africa. Most Africans live in rural areas that are tough to wire for internet access. (16) Now, some phone companies are trying to introduce Internet-ready phones into African markets. Certain companies have started selling simple smartphones for only $20. Previously, the lowest price had been around $40, well out of reach for many people. These devices are powered by software from the giant electronics company, KaiOS Technologies Limited. (17) Most companies are trying to make phones ever more powerful and capable, but KaiOS went the other way. It made every effort to keep the essential capabilities of smartphones, but strip out costs and preserve battery life for people who likely have inadequate access to electricity. The KaiOS devices offer an alternative to the more expensive models that remain out of reach to many Africans and contribute to the digital divide. (18) The body of KaiOS phones is as basic as it gets. Instead of a touchscreen, they’re controlled with an old-school keypad. They’re designed for 3G networks because 4G coverage doesn’t reach two thirds of Africa’s customers. In total, KaiOS phones are made from about $15 worth of parts, while Apple’s top of the line iPhone has $390 worth of stuff.Questions 16 to 18 are based on the passage you have just heard.Q16. What are a number of phone companies trying to do in Africa? 答案: D)Q17. How do KaiOS smartphones differ from smartphones of most other companies? 答案: A)Q18. What are KaiOS smartphones equipped with? 答案: B)Passage Two(19) For years, using recycled plastic to make plastic products was cheap. By contrast, fossil fuel plastic was more expensive. Thus, the sustainable option was an economic option too. But now it is cheaper for major manufacturers to use new plastic.According to one recent business report, recycled plastic now costs an extra $72 a tonne compared with newly made plastic. This may be because of consumer demands. They are pushing for more recycled plastics in new products. (20) Meanwhile, new plastic is becoming cheaper. This is because of a boom in petroleum chemical production from the U.S.The price increase of recycled plastic could cost sustainable manufacturers an extra $250m a year. Smaller manufacturers may also be forced to use new plastic to reduce costs. Makers of clear plastic bottles may also opt for new fossil-fuel based plastic to save money. Plastic packaging makers are being pressured to use more recycled plastic. This is done in hopes of reducing the enormous amount of plastic pollution in the oceans.(21) The UK government plans to tax companies which don’t use at least 30% recycled plastic in thei r products. Additionally, the government is planning to increase the quantity of recycled plastic in the market. This could mean incentives for new recycling plants. Additionally, recycling facilities may be improved at a local council level and recycled plastic could be imported. This would help increase the amount of recycled plastic in circulation.Questions 19 to 21 are based on the passage you have just heard.Q19. What is said about using recycled plastic to make plastic products in the past? 答案: C)Q20. What has led to a more competitive price for new plastic? 答案: D)Q21. What does the UK government plan to do about plastic? 答案: D)Passage Three(22) At the Dreamery, a business in Manhattan, naps are for sale. A 45-minute session in a darkened enclosure with peace and quiet costs $25. To be clear, this institution is no hotel. This is a nap joint. It sells the idea of the nap as much as the nap itself.Is a nap worth $25? The answer is obviously yes.(23) Here, at this point in the argument, it’s traditional for me to bring up all the studies that show the benefits of napping. But do you really need experts to tell you that? Just look at the world around you at 2:30 in the afternoon.I’ve been working from home for more than 10 years now. (24) And the quality and quantity of work I can do emerges directly from my ability to concentrate. I don’t understand how people have creative careers without napping.Every day at about 1 p.m., everyone faces the same choice: sleep until 2 p.m. and then work until 5 or daydream and drift around social media and attend pointless meetings until 7 p.m.(25) The friends I have who still work in offices inform me that bosses insist they take the second option and that napping is associated with laziness. I genuinely find it odd, for if you nap properly, it’s like waking up from a full night’s sleep and you can double your day’s worth of concentration. Questions 22 to 25 are based on the passage you have just heard.Q22. What do we learn about the Dreamery, a business in Manhattan? 答案: B)Q23. Why does the speaker ask us to look at the world around us at 2:30 in the afternoon? 答案:C)Q24. What do we learn about the quantity and quality of the speaker’s work? 答案: B)Q25. What does the speaker say he finds odd? 答案: A)。

蒸汽爆破对膳食纤维的影响及应用研究进展

孙金淏，焦文雅，吴超，等. 蒸汽爆破对膳食纤维的影响及应用研究进展[J]. 食品工业科技，2023，44（20）：449−457. doi:10.13386/j.issn1002-0306.2022120026SUN Jinhao, JIAO Wenya, WU Chao, et al. Research Progress in the Effect of Steam Explosion on Dietary Fiber and Its Application[J].Science and Technology of Food Industry, 2023, 44(20): 449−457. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022120026· 专题综述 ·蒸汽爆破对膳食纤维的影响及应用研究进展孙金淏，焦文雅，吴　超，于文龙，米　思，王向红*（河北农业大学食品科技学院，河北保定 071000）摘　要：蒸汽爆破是一种绿色、高效、能耗低的创新加工技术。

近年来广泛应用于废弃物资源的开发和利用，提高其综合价值。

在食品加工领域，蒸汽爆破技术的利用能够提高食品中活性物质的提取率，提高膳食纤维的品质，使其具有更强的理化特性和功能性质。

本文综述了蒸汽爆破技术的工作原理，蒸汽爆破处理使膳食纤维表面形成孔隙，沟槽缝隙增大，还使可溶性膳食纤维增加，不溶性膳食纤维减少。

在加工过程中能提高抗氧化性、阳离子交换作用、胆固醇吸收等功能活性，旨在提高富含膳食纤维植物及其副产品的经济价值和利用率，并为膳食纤维功能食品的开发和应用提供理论参考。

关键词：蒸汽爆破，膳食纤维，功能性质，综合利用本文网刊:中图分类号：TS209 文献标识码：A 文章编号：1002−0306（2023）20−0449−09DOI: 10.13386/j.issn1002-0306.2022120026Research Progress in the Effect of Steam Explosion on Dietary Fiberand Its ApplicationSUN Jinhao ，JIAO Wenya ，WU Chao ，YU Wenlong ，MI Si ，WANG Xianghong *（College of Food Science and Technology, Hebei Agricultural University, Baoding 071000, China ）Abstract ：Steam explosion is a green, efficient and low energy consumption innovative processing technology, which has been widely used in the development and utilization of waste resources to improve their comprehensive value, in recent years. In the field of food processing, the use of steam explosion technology can improve the extraction rate of active substances in food and the quality of dietary fiber, so that they have stronger physical and chemical properties and functional properties. This paper summarizes the working principle of steam explosion technology and it can form pores on the surface of dietary fiber, increase the groove gap, increase the soluble dietary fiber and reduce the insoluble dietary fiber.It can improve the functional activities such as oxidation resistance, cation exchange and cholesterol absorption during processing. The purpose is to improve the economic value and utilization rate of plants rich in dietary fiber and its by-products, and provide theoretical reference for the development and application of functional food with dietary fiber.Key words ：steam explosion ；dietary fiber ；functional nature ；comprehensive utilization膳食纤维是一种不能被人体消化吸收，也不能产生能量的多糖，曾被认为是一种“无营养物质”而长期得不到足够的重视，主要包含纤维素、抗性淀粉、果胶等[1−2]。

克服困难做蛋糕作文英语

When faced with the challenge of baking a cake,one might encounter various difficulties that require patience,creativity,and a bit of ingenuity.Heres a detailed account of how one might overcome these obstacles to create a delicious dessert.Initial Planning and Preparation:The first step in baking a cake is to gather all the necessary ingredients and tools. Sometimes,you might find yourself missing a crucial ingredient.In such cases, researching suitable substitutes can be a lifesaver.For instance,if youre out of baking powder,a mix of vinegar and baking soda can be used as a replacement.Measuring Ingredients:Accuracy in measuring ingredients is vital for a successful cake.If you dont have measuring cups,you can use everyday items like a tablespoon or even a bottle cap to measure out the required amounts.Consistency is key,so ensure you level off the ingredients to get the correct measurements.Mixing Techniques:When mixing the batter,its essential to understand the difference between folding and stirring.Overmixing can lead to a tough cake,while undermixing might result in an uneven texture.If youre unsure,start by gently mixing the wet and dry ingredients until just combined,then fold in any additional elements like chocolate chips or nuts.Baking Equipment:Not having the right baking pan can be a setback.If your desired pan is unavailable,you can use a similarsized pan,but be aware that this might affect the baking time and the final shape of the cake.Adjust the temperature and time accordingly to prevent over or underbaking.Temperature Control:Ovens can have hot spots,which can lead to uneven baking.To counter this,rotate the cake halfway through the baking process.If your oven runs hot or cold,use an oven thermometer to ensure the temperature is accurate.Preheating the oven is also crucial to avoid a slow start in baking.Decorating Dilemmas:When it comes to decorating,you might face challenges like frosting thats too runny or too thick.To thicken frosting,add more powdered sugar.If its too thick,a bit of milk or cream can help.Practice your piping skills on a piece of parchment paper before applying them to the cake to avoid mistakes.Time Management:Baking a cake often requires timing precision,especially when multitasking between preparing the batter,preheating the oven,and cleaning up.Setting a timer for each step can help you stay organized and ensure that each part of the process is completed in a timely manner.Creative Problem Solving:If a recipe calls for a specific type of cake pan that you dont own,consider using a different shape or size and adjust the recipe accordingly.For example,if youre making a layer cake but only have a bundt pan,you can still create a beautiful presentation by slicing and stacking the cake.Learning from Mistakes:Not every cake will turn out perfect,and thats okay.Each baking experience is an opportunity to learn.If your cake didnt rise as expected,consider factors like the freshness of your baking powder or the temperature of your ingredients.Reflect on what went wrong and how you can improve next time.Sharing the Journey:Sometimes,the process of baking can be as rewarding as the final product.Share your experiences,challenges,and triumphs with friends or family.They can offer support, advice,or even join in the fun of baking together.In conclusion,overcoming difficulties in baking a cake is all about adapting to the situation,being resourceful,and learning from each attempt.With practice and persistence,youll soon be able to create cakes that are not only delicious but also a testament to your baking skills and creativity.。

油茶的制英语作文500字左右

油茶的制英语作文500字左右英文回答：Tea oil, extracted from the seeds of the Camellia oleifera tree, is a highly prized oil in Chinese cuisine and medicine. It is renowned for its rich nutty flavor, high smoke point, and numerous health benefits.The tea oil extraction process begins with harvesting the mature seeds from the tea oil tree. The seeds are then hulled and dried to remove the outer shell. The kernels are then cold-pressed to extract the oil. Cold-pressing preserves the oil's delicate flavor and nutrients.Tea oil is a versatile cooking oil that can be used for frying, stir-frying, and even as a salad dressing. Its high smoke point makes it ideal for high-heat cooking without burning. Tea oil is also rich in antioxidants, polyphenols, and vitamins, making it beneficial for cardiovascular health, skin care, and hair care.In traditional Chinese medicine, tea oil has been used for centuries to treat various ailments. It is believed to have anti-inflammatory, antibacterial, and anti-cancer properties. Tea oil is often used topically to treat skin conditions such as eczema and psoriasis.中文回答：油茶的制作过程：1. 采摘，成熟的油茶籽从油茶树上采摘。

手工制作和机械制作区别英文作文题目

手工制作和机械制作区别英文作文题目Handmade and Mechanical Production: What's the Difference?Handmade production and mechanical production are two different approaches to creating goods. While both methods aim to produce high-quality products, they have distinct differences in terms of process, quality, and artistic value.Handmade production involves creating goods by hand, using traditional techniques and craftsmanship. This method often requires skilled artisans who have mastered their craft over many years. Handmade products are known fortheir attention to detail, unique features, and artistic value. Each product is one-of-a-kind, as it bears the mark of the artisan who created it. Handmade production is often associated with traditional crafts such as pottery, woodworking, and textile arts.On the other hand, mechanical production relies on machines and technology to create goods on a large scale. This method is often used in manufacturing industries tomass-produce products quickly and efficiently. Mechanical production can produce a large quantity of goods with consistent quality and precision. However, the productslack the individuality and artistic value of handmade goods, as they are often standardized and uniform.In terms of quality, handmade products are often considered to be of higher quality than mechanically produced goods. This is because artisans pay closeattention to every detail and use high-quality materials, resulting in products that are durable and long-lasting. In contrast, mechanical production often prioritizes speed and efficiency, which can sometimes compromise the quality of the final product.Artistic value is another key difference between handmade and mechanical production. Handmade goods areoften appreciated for their artistic merit and the skill of the artisan who created them. Each piece tells a story and reflects the creativity and personality of the maker. Onthe other hand, mechanically produced goods are valued for their functionality and affordability, but they may lackthe artistic flair and individuality of handmade products.In conclusion, handmade and mechanical production aretwo distinct approaches to creating goods, each with itsown set of advantages and limitations. While handmade production emphasizes craftsmanship, artistic value, and individuality, mechanical production focuses on efficiency, consistency, and mass production. Both methods have their place in the market, and consumers can choose based ontheir preferences for quality, artistic value, and uniqueness.手工制作和机械制作的区别：手工制作和机械制作是两种不同的方法来创造商品。

关于机械加工的英语作文范文

关于机械加工的英语作文范文Mechanical machining is a process of changing the shape, size, and surface of workpieces by removing unwanted materials using various cutting tools. It is one of the most important manufacturing processes in the modern industry and plays a vital role in producing high-quality products.The importance of mechanical machining lies in its ability to create parts with high precision and accuracy. This is achieved through careful planning, tool selection, and machine setup. In order to achieve the desired results, machinists must possess a wide range of skills, including knowledge of different materials and their properties, proficiency in reading technical drawings, and familiarity with various types of machines and cutting tools.There are several techniques involved in mechanical machining, each with its own advantages and limitations. Turning is one such technique that involves rotating the workpiece against a stationary cutting tool to removematerial. This technique is commonly used for creating cylindrical shapes. Milling is another widely usedtechnique that involves moving a cutting tool across the surface of the workpiece to create complex shapes and contours.Other common techniques include drilling, boring, threading, grinding, and honing. Each technique requires specifictools and machines to achieve the desired results.In addition to traditional methods, recent advancements in technology have led to new techniques such as CNC (computer numerical control) machining. This method allows forgreater precision and accuracy by controlling machines through software programs. It has become increasingly popular due to its efficiency and ability to produce complex shapes with ease.Despite its importance in modern manufacturing processes, mechanical machining faces some challenges as well. One major challenge is the increasing demand forenvironmentally friendly processes that reduce waste andpromote sustainability. Machinists are now exploring new methods such as water jet cutting and laser cutting that are more eco-friendly than traditional methods.In conclusion, mechanical machining is an essential process in modern manufacturing that allows for precise shaping of workpieces using various techniques. With advancements in technology leading to new methods such as CNC machining, it will continue to play an important role in producing high-quality products while facing challenges related to environmental concerns.。

易拉罐生产流程雅思英文写作

易拉罐生产流程雅思英文写作The Production Process of Aluminium Cans.The aluminium can, a ubiquitous sight in our daily lives, is a remarkable testament to the advancement of technology and the innovation of the packaging industry.Its production process, while seemingly straightforward, is actually a highly specialised and intricate dance of machines, metals, and chemicals. This article delves into the intricate steps that transform raw aluminium into the sleek, recyclable containers we know and love.Step 1: Raw Materials.The journey begins with the mining of bauxite, an ore that is rich in aluminium hydroxide. This ore is then smelted in a process called the Bayer Process, which extracts the aluminium oxide from the bauxite. The oxide is then further processed to produce aluminium metal, which is the raw material for aluminium cans.Step 2: Can Body Fabrication.Once the aluminium metal is ready, it is rolled into sheets, which are then cut into circles. These circles are then fed into a can-making machine, where they are drawn and ironed into the familiar cylindrical shape of a can body. This process requires precision engineering to ensure that each can is the perfect balance of strength and lightness.Step 3: End and Side Seaming.After being formed, the can bodies are then ready for the end and side seams. This involves welding the ends of the can to its body, creating a secure and leak-proof seal. The side seams, on the other hand, are where the sides of the can are welded together, ensuring its structural integrity.Step 4: Printing and Coating.The next step is to give the cans their distinctive look. This involves printing the desired graphics, labels, and instructions on the can's surface. The printing is usually done using high-quality inks that are specifically formulated for use on aluminium. Additionally, a protective coating is applied to preserve the print and give the can a shiny, appealing finish.Step 5: Filling and Sealing.After printing and coating, the cans are filled withthe desired product, which could range from beverages to food items. Once filled, the cans are sealed, usually witha metal or plastic lid, to ensure that the contents remain fresh and unspoiled.Step 6: Quality Control.Throughout the production process, rigorous quality control measures are implemented to ensure that each can meets the highest standards. This includes checks for leaks, structural integrity, and print quality. Only cans thatpass these tests are sent out for packaging and distribution.Step 7: Packaging and Distribution.Finally, the cans are packaged in cases or trays and ready for distribution. They are then loaded onto trucks or ships and sent to their destination, ready to be sold and used by consumers.In conclusion, the production of aluminium cans is a remarkable feat of engineering and technology. It involves multiple steps, each requiring meticulous attention to detail and strict quality control measures. The result is a durable, recyclable container that is not only functional but also aesthetically pleasing. As we enjoy the contents of our aluminium cans, it's worth taking a moment to appreciate the complex process that brought them to us.。

下午水果加工英语作文案

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机械传统加工工艺英语作文Traditional mechanical machining is a craft that's been around for ages. It's all about using tools and machines to shape metal or other materials into precise parts. You know, it's not just about cutting and grinding, it's an art form.Imagine the sound of a lathe whirring as it carves outa perfect cylinder. Or the sight of sparks flying from a grinding wheel as it hones down a rough edge. These are the sights and sounds of traditional machining.The tools themselves are fascinating. From the simple drill bit to the complex milling machine, each has its own purpose and can achieve incredible accuracy. And it's not just about metalworking; plastic, wood, and even glass can be machined with the right techniques.But it's not all about the machines. It's the skilled craftsmen who operate them that make the real difference. They have an intuitive understanding of materials and howthey respond to different cutting forces. It's this combination of knowledge and skill that produces parts that are not just functional, but also beautiful.Nowadays, with all the advances in technology, CNC machines and 3D printing are becoming more common.。

制造的原理儿童英语

制造的原理儿童英语Manufacturing Principles in Simple English for Children IntroductionManufacturing is the process of transforming rawmaterials into finished products through a series of steps.It involves a combination of machines, tools, and human labor to create the goods we use in our daily lives. In this document, we will explore the basic principles of manufacturing in simple English so that children can understand the process.Understanding Raw MaterialsTo start the manufacturing process, we need raw materials. Raw materials can be natural resources like wood, clay, cotton, or synthetic materials like plastic, metal, or glass. These materials are collected from nature or produced in factories. They serve as the foundation for creatingdifferent products.Designing and PlanningOnce we have the raw materials, the next step isdesigning and planning. Engineers and designers use their imaginations to come up with ideas for new products. Theydraw sketches and create prototypes to visualize how thefinal product will look. They also plan the steps and machines required to manufacture the product.Processing the Raw MaterialsAfter designing and planning, the raw materials gothrough various processing steps. For example, if the product requires metal, the metal is melted and molded into thedesired shape. In the case of plastics, they are heated andmolded using specialized machines. These processes shape the raw materials into the specific parts needed for the final product.Assembling the PartsOnce the parts are ready, they are assembled to create the final product. Assembly can involve using screws, glue, or other fasteners to connect the different parts together. This step requires precision and attention to detail to ensure that all the parts fit together perfectly.Testing and Quality ControlBefore the manufactured product is ready for sale, it undergoes testing and quality control measures. This ensures that the product meets certain standards and is safe to use. Testers analyze the product's durability, functionality, and safety features to make sure it performs as intended. Packaging and DistributionOnce the product passes the quality control tests, it is packaged and prepared for distribution. Packaging protects the product during transportation and provides information to the consumers about the product. The packaged goods are then distributed to stores or directly to customers through online shopping platforms.ConclusionIn conclusion, manufacturing is a complex process that involves transforming raw materials into finished products. It requires careful planning, processing, and quality control measures to create products that meet our needs. By understanding the principles of manufacturing, children can appreciate the effort that goes into making the items they use every day.Remember, the process of manufacturing is important for creating goods, but it's also crucial to consider the impact on the environment. We should strive for sustainable manufacturing practices to protect our planet for future generations.。

如何生产什么什么英语作文

如何生产什么什么英语作文The Process of Producing [Insert Product Here]Introduction.The journey of producing any product, whether it's a physical good or a service, is a complex and intricate one. It involves multiple stages, each with its unique challenges and requirements. In this essay, we'll delveinto the general steps involved in the production process, with a focus on the key elements that contribute to the creation of a high-quality product.1. Market Research and Ideation.Before any physical production begins, a thorough understanding of the market is crucial. Market research helps identify consumer needs, trends, and competition. This data is then used to develop a product concept that meets those needs and differentiates itself from existingoptions. The ideation stage involves brainstorming and concept testing to refine the initial idea into a viable product concept.2. Design and Development.Once the product concept is solidified, the designphase begins. This involves creating a detailed plan forthe product, including its physical attributes, functionality, and user experience. Designers work closely with engineers to ensure that the design is both aesthetically pleasing and structurally sound. Prototypes are created and tested to identify any design flaws or issues.3. Material Sourcing.During the production planning stage, it's essential to source the necessary materials and components. Thisinvolves identifying reliable suppliers, negotiating prices, and ensuring the quality of the materials meets theproduct's specifications. Additionally, environmental andethical considerations, such as sustainable sourcing and fair trade practices, are becoming increasingly importantin this phase.4. Manufacturing.The manufacturing phase is where the physical product takes shape. This involves converting the raw materials and components into the final product using various processes such as machining, assembly, and packaging. Strict quality control measures are implemented to ensure consistency and durability. Automation and robotics are increasingly being used to improve efficiency and reduce errors.5. Quality Assurance and Testing.Quality assurance is a crucial part of the production process. It involves rigorous testing to ensure that each product meets the specified standards. This includes functional testing, durability testing, and user acceptance testing. Any products that fail to meet the standards are either repaired or discarded to maintain the brand'sreputation.6. Marketing and Distribution.After the product is ready, the focus shifts to marketing and distribution. Marketing strategies are designed to raise awareness about the product, create demand, and differentiate it from competitors. Distribution channels are established to reach the target market efficiently. Online platforms, retail stores, and direct sales are all potential options.7. Post-Production Support and Feedback.Even after the product reaches the market, the production cycle continues. Post-production support involves providing customer service, handling product returns or exchanges, and collecting feedback. This feedback is then used to improve future products, ensuring continuous improvement and innovation.Conclusion.Producing a product is a multifaceted process that requires careful planning, execution, and continuous improvement. It involves more than just converting raw materials into a final good; it's about creating a product that meets the needs of the market, exceeds consumer expectations, and contributes to the overall growth and success of a business. By focusing on each step of the process, companies can ensure that they produce high-quality products that will resonate with their target audience.。

茶叶加工方式英语作文

茶叶加工方式英语作文Title: The Process of Tea Production。

Tea, a beverage cherished worldwide for its aroma, taste, and health benefits, undergoes a meticulous process from leaf to cup. In this essay, we delve into theintricate steps of tea processing, exploring the techniques involved in transforming freshly plucked leaves into the flavorful brew enjoyed by millions.1. Plucking: The journey of tea production begins in the fields, where skilled harvesters carefully pluck the tender leaves and buds from the tea bushes. This step is crucial, as it determines the quality and flavor profile of the final product. Generally, only the top two leaves and the bud are harvested, ensuring optimal taste and aroma.2. Withering: After plucking, the leaves undergo withering, a process that involves spreading them out to wilt. This step reduces the moisture content of the leaves,making them more pliable for subsequent processing. Withering can take place naturally, where the leaves are laid out in the open air, or artificially, using controlled temperature and humidity conditions.3. Rolling: Next, the withered leaves are rolled to break their cell walls and release the natural juices and oils contained within. This step is crucial for initiating the oxidation process, which contributes to the development of flavor and color in the tea. Traditionally, rolling was done by hand, but modern methods employ machinery for efficiency and consistency.4. Oxidation/Fermentation: Oxidation, also known as fermentation, is a pivotal stage in tea processing, where the rolled leaves are exposed to oxygen. This biochemical reaction catalyzes the transformation of compounds within the leaves, resulting in the characteristic flavors and colors associated with different types of tea. The duration of oxidation varies depending on the desired type of tea, ranging from minimal oxidation for green tea to extensive oxidation for black tea.5. Fixation/Kill-Green: To halt the oxidation process at the desired stage, the leaves undergo fixation, also known as kill-green. This step involves subjecting the leaves to high temperatures, typically through steaming or pan-firing. Fixation not only arrests oxidation but also preserves the freshness and aroma of the tea.6. Drying: Once fixation is complete, the tea leaves are dried to remove excess moisture and stabilize their flavor and aroma. Drying can be achieved through various methods, including air-drying, baking, or using specialized drying machines. Proper drying is essential for prolonging the shelf life of the tea and maintaining its quality.7. Sorting and Grading: After drying, the tea leaves are sorted and graded based on size, shape, color, and quality. This meticulous process ensures consistency in the final product and allows for the classification of teasinto different grades, such as whole leaf, broken leaf, and fannings. The sorting and grading stage is crucial for meeting market demands and maintaining the reputation oftea estates.8. Packaging: The final step in tea processing involves packaging the graded tea for distribution and consumption. Tea is often packaged in various forms, including loose leaf, tea bags, or compressed into bricks or cakes. Proper packaging preserves the freshness and flavor of the tea, ensuring a delightful drinking experience for consumers.In conclusion, the journey of tea from leaf to cup is a fascinating blend of tradition and modernity, craftsmanship, and technology. Each step in the tea processing chain plays a crucial role in shaping the final product, reflecting the rich diversity and cultural significance of this beloved beverage. Through careful cultivation and processing, tea artisans continue to delight tea enthusiasts worldwide with an array of flavors and aromas to savor and enjoy.。

传统机械加工工艺英语作文

传统机械加工工艺英语作文Traditional Mechanical Machining TechnologyMechanical machining is the process of shaping metal and other materials into specific shapes and sizes using various tools and machines. This process has been used for centuries and has evolved over time to become moreefficient and precise. In this article, we will discuss the traditional mechanical machining technology that has been used for many years.TurningThe most common type of mechanical machining is turning. This process involves rotating a workpiece on a lathe and using a cutting tool to remove material from the surface of the workpiece. Turning can be used to create cylindrical shapes, as well as tapered and contoured shapes. The lathe is a versatile machine that can be used for a variety of turning applications, from small parts to large components.MillingMilling is another common mechanical machining process that involves removing material from a workpiece using arotating cutting tool. The tool moves across the surface of the workpiece to create a flat or contoured shape. Milling machines can be used for a variety of applications, from creating simple shapes to complex parts with intricate details.DrillingDrilling is a process that involves creating holes in a workpiece using a drill bit. The drill bit is rotated at high speeds and pressed into the workpiece to create a hole. Drilling can be used to create holes of various sizes and shapes, and can be used to create through holes or blind holes.GrindingGrinding is a process that involves removing material from a workpiece using an abrasive wheel. The wheel is rotated at high speeds and pressed against the surface of the workpiece to remove material. Grinding can be used to create a smooth surface finish, as well as to remove excess material from a workpiece.BroachingBroaching is a process that involves removing material from a workpiece using a broach. The broach is a long, narrow cutting tool with multiple teeth that gradually increase in size. The broach is inserted into the workpiece and pulled through to remove material. Broaching can be used to create internal and external shapes, as well as to create keyways and splines.LappingLapping is a process that involves creating a smooth, polished surface on a workpiece using a lapping plate and abrasive slurry. The workpiece is placed on the lapping plate, and the abrasive slurry is applied to the surface. The plate is rotated, and the workpiece is moved across the surface to create a smooth, polished finish.HoningHoning is a process that involves creating a smooth, polished surface on the inside of a cylindrical workpiece using an abrasive stone. The stone is rotated and moved back andforth inside the workpiece to remove material and create a smooth, polished surface.ConclusionMechanical machining is a process that has been used for centuries to create precision parts and components. The traditional mechanical machining technologies discussed in this article are still widely used today, although they have evolved to become more efficient and precise. While there are many modern machining technologies available, traditional mechanical machining still plays an important role in many industries.。

咖啡加工的英文作文

咖啡加工的英文作文Coffee processing involves several steps, including harvesting, drying, milling, roasting, and packaging. The first step is harvesting, where ripe coffee cherries are picked from the trees by hand or machine. The cherries are then sorted to remove any unripe or overripe ones, ensuring only the best quality cherries are used for processing.After harvesting, the coffee cherries need to be dried to reduce their moisture content. This can be done using various methods, such as sun-drying or machine-drying. Once the cherries are dried, they are ready for the milling process, where the outer layers of the cherries are removed to reveal the green coffee beans inside.The next step in coffee processing is roasting, whichis a crucial step that greatly influences the flavor and aroma of the coffee. During roasting, the green coffee beans are heated to high temperatures, causing them to change in color, taste, and smell. The length andtemperature of the roasting process can be adjusted to achieve different levels of roast, from light to dark.Once the coffee beans are roasted, they are ready to be packaged for distribution and consumption. Packaging can vary from simple bags to vacuum-sealed containers, depending on the intended market and shelf life of the coffee. Proper packaging is essential to preserve the freshness and quality of the coffee beans until they reach the consumer.In conclusion, coffee processing is a complex andmulti-step process that requires careful attention todetail at every stage. From harvesting to packaging, each step plays a crucial role in determining the final quality and taste of the coffee. Whether it's a light, medium, or dark roast, the art of coffee processing is what brings out the unique flavors and aromas that coffee lovers enjoy.。

炒菜英语作文

When it comes to cooking,stirfrying is a popular and efficient method,especially in Chinese cuisine.It involves cooking ingredients quickly over high heat in a small amount of oil,which not only preserves the nutrients and flavors of the ingredients but also ensures that the dish is served hot and fresh.Heres a detailed guide on how to write an essay on stirfrying in English,focusing on the process,benefits,and some common dishes.Title:The Art of StirFryingIntroductionStirfrying is a culinary technique that has been perfected over centuries in Asian kitchens, particularly in China.It is a method of cooking that combines speed with flavor,creating a symphony of tastes and textures that are hard to resist.This essay will delve into the intricacies of stirfrying,exploring its history,the science behind it,and how it has become a staple in many households around the world.The Process of StirFrying1.Preparation:The first step in stirfrying is to prepare all the ingredients.This includes chopping vegetables and proteins into bitesized pieces to ensure even cooking.2.Heating the Wok:A wok is the traditional pan used for stirfrying.It is heated until it is very hot,almost smoking,before adding oil.This high heat is crucial for the success of the dish.3.Adding Oil:A small amount of oil is added to the wok,just enough to coat the bottom. The choice of oil can affect the flavor of the dish,with peanut oil being a popular choice for its high smoke point and nutty flavor.4.Cooking the Protein:Proteins such as chicken,beef,or tofu are added first.They are quickly seared to lock in their flavors before being removed from the wok.5.Adding Vegetables:Vegetables are added next,starting with the ones that take longer to cook,like carrots and bell peppers,and then adding leafy greens towards the end.6.Stirring:The key to stirfrying is constant motion.The ingredients are stirred continuously to ensure even cooking and to prevent them from sticking to the wok.7.Seasoning:Seasonings such as soy sauce,garlic,and ginger are added towards the endof the cooking process.The dish is then quickly tossed to combine the flavors.8.Serving:The dish is served immediately to enjoy the flavors at their peak.Benefits of StirFryingStirfrying is not only a delicious way to prepare food but also a healthy one.The high heat and short cooking time help to retain the nutrients in the vegetables and proteins.It is also a lowfat cooking method,as only a small amount of oil is used.Common StirFry DishesStirfrying is a versatile technique that can be used to create a wide range of dishes.Some popular stirfry dishes include:Kung Pao Chicken:A spicy stirfry with chicken,peanuts,and vegetables,seasoned with Sichuan peppercorns and chili.Beef and Broccoli:Tender slices of beef cooked with broccoli in a savory sauce.Vegetable StirFry:A vegetarian option that showcases the natural flavors of a variety of vegetables.Shrimp StirFry:Light and flavorful,this dish features shrimp cooked with a mix of vegetables and a tangy sauce.ConclusionStirfrying is more than just a cooking method it is an art form that brings together flavors and textures in a harmonious dance.It is a testament to the culinary traditions of Asia and continues to be a beloved method of cooking in homes and restaurants around the world. Whether you are a seasoned chef or a home cook,the art of stirfrying offers a delicious and healthy way to prepare meals that are sure to please the palate.。

The Hydrogen Production in Wastewater Treatment

The Hydrogen Production in Wastewater TreatmentWastewater treatment is a crucial process that helps in cleaning up wastewater before it is released into the environment. However, wastewater treatment plants also produce a significant amount of hydrogen, which is a valuable resource. Hydrogen is a clean and renewable energy source that can be used in various applications, including fuel cells, transportation, and power generation. Therefore, the hydrogen production in wastewater treatment is an important aspect that needs to be explored further.One of the main benefits of producing hydrogen from wastewater treatment is that it can help in reducing greenhouse gas emissions. Hydrogen is a clean fuel that produces only water and heat when it is burned, which means that it does not emit any harmful pollutants. By producing hydrogen from wastewater treatment, we can reduce the dependence on fossil fuels and promote sustainable energy sources.Another benefit of hydrogen production in wastewater treatment is that it can help in reducing the cost of wastewater treatment. The process of producing hydrogen from wastewater treatment involves using microbes to break down organic matter in the wastewater. This process also produces hydrogen as a byproduct, which can be captured and used as an energy source. By using the hydrogen produced in wastewater treatment, we can reduce the cost of energy needed to run the treatment plant.However, there are also challenges associated with hydrogen production in wastewater treatment. One of the main challenges is the low concentration of hydrogen in the wastewater. The amount of hydrogen produced in wastewater treatment is relatively small, which means that it may not be enough to meet the energy needs of the treatment plant. Therefore, additional energy sources may be required to supplement the hydrogen produced from wastewater treatment.Another challenge associated with hydrogen production in wastewater treatment is the cost of the technology. The process of producing hydrogen from wastewater treatment involves using specialized equipment and technology, which can be expensive to install andmaintain. Therefore, the cost of producing hydrogen from wastewater treatment needs to be carefully evaluated to ensure that it is economically feasible.In conclusion, the production of hydrogen in wastewater treatment is an important aspect that needs to be explored further. While there are benefits associated with hydrogen production, such as reducing greenhouse gas emissions and reducing the cost of wastewater treatment, there are also challenges that need to be addressed. Therefore, further research and development are needed to optimize the production of hydrogen in wastewater treatment and make it economically feasible. By doing so, we can promote sustainable energy sources and reduce our dependence on fossil fuels.。

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