PINGYAO hand-polished lacquerware has been widely considered as one of the four most famed lacquerware types in China.It originated more than 2,000 years ago in what is called Pingyao County today,in Jinzhong City,cen...PINGYAO hand-polished lacquerware has been widely considered as one of the four most famed lacquerware types in China.It originated more than 2,000 years ago in what is called Pingyao County today,in Jinzhong City,central China’s Shanxi Province.Its fame is due to the exquisite and unique skill of polishing lacquered coating with bare hands during the manufacturing process.This quaint and durable lacquerware boasts both aesthetic and practical values,and is characterized by its distinguished appearance and glossy sheen.It comes in the forms of jewelry boxes,utensils and stationery,screens and furniture.展开更多
The present investigation was aimed to study functional properties,antioxidant activity and in-vitro digestibility characteristics of brown and polished flours obtained from four rice cultivars(SR-4,K-39,Mushq Budij a...The present investigation was aimed to study functional properties,antioxidant activity and in-vitro digestibility characteristics of brown and polished flours obtained from four rice cultivars(SR-4,K-39,Mushq Budij and Zhag)of Kashmir.Brown rice flours had higher total dietary fibre(3.08%-3.68%),oil absorption(116.0%-139.0%),emulsion capacity(4.78%-9.52%),emulsion stability(87.46%-99.93%)and resistant starch content(6.80%-9.00%)than polished flours.However,polished flours presented greater water absorption(102.0%-122.0%),foaming capacity(8.00%-13.63%),apparent amylose(19.16%-22.62%),peak(2260.0-2408.0 cP),trough(1372.0-1589.0 cP)and breakdown(714.0-978.0 cP)viscosities than their brown counterparts.Brown rice flours depicted highest total phenolic content(4.40-6.40 mg GAE/g)and inhibition of lipid peroxidation(19.50%-33.20%).However,equilibrium starch hydrolysis percentage(C∞)and predicted glycemic index of brown rice flours were lower than their polished counterparts.Among rice cultivars,brown Zhag flour had the highest total dietary fibre(3.68%),emulsion capacity(9.52%),emulsion stability(99.93%),resistant starch(9.00%),DPPH radical scavenging activity(85.45%)and inhibition of lipid peroxidation(33.20%),respectively.Emulsion capacity and emulsion stability were positively correlated with protein content of rice flours.However,peak,trough,breakdown and setback viscosities were negatively correlated with protein and fat contents of rice flour.The present investigation will be helpful in identifying nutritive role of rice flours from studied cultivars in human diet.展开更多
Transmission characteristics of the side polished fiber were studied by experimental method.The side polished fibers with different depth and length were implemented,and the corresponding wavelength dependent loss was...Transmission characteristics of the side polished fiber were studied by experimental method.The side polished fibers with different depth and length were implemented,and the corresponding wavelength dependent loss was measured.Based on wheel fabrication,the side polished fibers were achieved with the low insertion loss and cost.Meanwhile,they can be artificially controlled for the use of evanescent field area and easy to system integration.展开更多
The performance of optical power transmission through a side-polished fiber on which materials of different refractive indices were overlaid is investigated. The experiments show that the transmitted optical power thr...The performance of optical power transmission through a side-polished fiber on which materials of different refractive indices were overlaid is investigated. The experiments show that the transmitted optical power through the side-polished fiber varies with the refractive index of the overlaid material. The result of our experiments fits well the theoretical calculation. Side-polished fiber manufactured by wheel polishing method can be used not only to control optical power transmission through the fiber core but also as a refractive index sensor.展开更多
The etching technique using Ce is a convenient and fast method for polishing and shaping diamond films. In this study, the influence of polishing parameters such as polishing temperature and time on the surface crysta...The etching technique using Ce is a convenient and fast method for polishing and shaping diamond films. In this study, the influence of polishing parameters such as polishing temperature and time on the surface crystallinity and phase composition of diamond films was thoroughly investigated via the analysis of Raman spectra such as FWHM and ID/IG. Moreover, the issue on the graphitization of diamond after polishing with Ce was further researched through the detailed study of the depth distribution of Raman data including FWHM and ID/IG, and a result completely different from the hot-iron metal polished ones was obtained. The results showed that polished diamond films had considerably higher diamond content than those before polishing, and not a bit of graphitization was found in the polished ones, owing to a higher solubility of carbon in rare earth metal Ce than that in transition metals, and the original crystallinity of the films polished with Ce did not deteriorate.展开更多
This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fuse...This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared (RMS) average surface roughness values are 0.7 nm and 1.0 rim, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive con- taminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics.展开更多
Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom c...Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.展开更多
Purpose: Bacterial adhesion represents the initial step in biofilm formation, dental caries and decay. This study aimed to evaluate and compare surface roughness and bacterial adhesion to bulk fill resin composites po...Purpose: Bacterial adhesion represents the initial step in biofilm formation, dental caries and decay. This study aimed to evaluate and compare surface roughness and bacterial adhesion to bulk fill resin composites polished with different systems. Methods: Filtek Z350 XT (Incremental-fill resin composite), Filtek Bulk-fill Posterior (Bulk-fill resin composite), and Tetric N Ceram (Bulk-fill resin composite) were used as resin composites. The polishing systems used in this study were Sof-Lex multi-step, PoGo one step, and Mylar strip. Scanning electron microscope (SEM) was used to examine the surface roughness and adhesion of Streptococcus mutans ATCC 25175 standard strain to bulk-fill resin composites. Results: The type of restorative materials did not affect the surface roughness or bacterial adhesion (p > 0.05) but the polishing systems were significant (p R = 0.943) between surface roughness and bacterial adhesion to the tested surfaces. Conclusion: Regardless of the restorative material, Mylar polishing system revealed the smoothest surface and the lowest adhesion of S. mutans as compared to Pogo one step and Sof-Lex multi-step polishing systems.展开更多
Side polished fiber(SPF)has a controllable average roughness and length of the side-polishing region,which becomes a versatile platform for integrating multiple materials to interact with the evanescent field to fabri...Side polished fiber(SPF)has a controllable average roughness and length of the side-polishing region,which becomes a versatile platform for integrating multiple materials to interact with the evanescent field to fabricate all-fiber devices and sensors.It has been widely used in couplers,filters,polarizers,optical attenuators,photodetectors,modulators,and sensors for temperature,humidity,strain,biological molecules,chemical gas,and vector magnetic monitoring.In this article,an overview of the development history,fabrication techniques,fiber types,transmission characteristics,and varied recent applications of SPFs are reviewed.Firstly,the fabrication techniques of SPFs are reviewed,including the V-groove assisted polishing technique and wheel polishing technique.Then,the different types of SPFs and their characteristics are discussed.Finally,various applications of SPFs are discussed and concluded theoretically and experimentally,including their principles and structures.When designing the device,the residual thickness and polishing lengths of the SPF need to be appropriately selected in order to obtain the best performance.Developing all-fiber devices and sensors is aimed at practical usability under harsh environments and allows to avoid the high coupling loss between optical fibers and on-chip integrated devices.展开更多
It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm.Traditional polishing methods are disabled to polish the component,meanw...It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm.Traditional polishing methods are disabled to polish the component,meanwhile keeping the structure intact.To overcome this challenge,small-grooved components made of aluminum alloy with sizes less than 1 mm were fabricated by a custom-made printer.A novel approach to multi-phase jet(MPJ)polishing is proposed,utilizing a self-developed polisher that incorporates solid,liquid,and gas phases.In contrast,abrasive air jet(AAJ)polishing is recommended,employing a customized polisher that combines solid and gas phases.After jet polishing,surface roughness(Sa)on the interior surface of grooves decreases from pristine 8.596μm to 0.701μm and 0.336μm via AAJ polishing and MPJ polishing,respectively,and Sa reduces 92%and 96%,correspondingly.Furthermore,a formula defining the relationship between linear energy density and unit defect volume has been developed.The optimized parameters in additive manufacturing are that linear energy density varies from 0.135 J mm^(-1)to 0.22 J mm^(-1).The unit area defect volume achieved via the optimized parameters decreases to 1/12 of that achieved via non-optimized ones.Computational fluid dynamics simulation results reveal that material is removed by shear stress,and the alumina abrasives experience multiple collisions with the defects on the heat pipe groove,resulting in uniform material removal.This is in good agreement with the experimental results.The novel proposed setups,approach,and findings provide new insights into manufacturing complex-structured components,polishing the small-grooved structure,and keeping it unbroken.展开更多
Ceramic cutting inserts are a type of cutting tool commonly used in high-speed metal cutting applications.However,the wear of these inserts caused by friction between the workpiece and cutting inserts limits their ove...Ceramic cutting inserts are a type of cutting tool commonly used in high-speed metal cutting applications.However,the wear of these inserts caused by friction between the workpiece and cutting inserts limits their overall effectiveness.In order to improve the tool life and reduce wear,this study introduces an emerging method called magnetic field-assisted batch polishing(MABP)for simultaneously polishing multiple ceramic cutting inserts.Several polishing experiments were conducted under different conditions,and the wear characteristics were clarified by cutting S136H steel.The results showed that after 15 min of polishing,the surface roughness at the flank face,edge,and nose of the inserts was reduced to below 2.5 nm,6.25 nm,and 45.8 nm,respectively.Furthermore,the nose radii of the inserts did not change significantly,and there were no significant changes in the weight percentage of elements before and after polishing.Additionally,the tool life of the batch polished inserts was found to be up to 1.75 times longer than that of unpolished inserts.These findings suggest that the MABP method is an effective way to mass polish ceramic cutting inserts,resulting in significantly reduced tool wear.Furthermore,this novel method offers new possibilities for polishing other tools.展开更多
The infrared conformal window is one of the most critical components in aircraft.Conformal windows with high performance bring low aberrations,high aerodynamic performance,reliability in extreme working environments,a...The infrared conformal window is one of the most critical components in aircraft.Conformal windows with high performance bring low aberrations,high aerodynamic performance,reliability in extreme working environments,and added value for aircraft.Through the past decades,remarkable advances have been achieved in manufacturing technologies for conformal windows,where the machining accuracy approaches the nanometer level,and the surface form becomes more complex.These advances are critical to aircraft development,and these manufacturing technologies also have significant reference values for other directions of the ultra-precision machining field.In this review,the infrared materials suitable for manufacturing conformal windows are introduced and compared with insights into their performances.The remarkable advances and concrete work accomplished by researchers are reviewed.The challenges in manufacturing conformal windows that should be faced in the future are discussed.展开更多
Diamond is a highly valuable material with diverse industrial applications,particularly in the fields of semiconductor,optics,and high-power electronics.However,its high hardness and chemical stability make it difficu...Diamond is a highly valuable material with diverse industrial applications,particularly in the fields of semiconductor,optics,and high-power electronics.However,its high hardness and chemical stability make it difficult to realize high-efficiency and ultra-low damage machining of diamond.To address these challenges,several polishing methods have been developed for both single crystal diamond(SCD)and polycrystalline diamond(PCD),including mechanical,chemical,laser,and ion beam processing methods.In this review,the characteristics and application scope of various polishing technologies for SCD and PCD are highlighted.Specifically,various energy beam-based direct and assisted polishing technologies,such as laser polishing,ion beam polishing,plasma-assisted polishing,and laser-assisted polishing,are summarized.The current research progress,material removal mechanism,and infuencing factors of each polishing technology are analyzed.Although some of these methods can achieve high material removal rates or reduce surface roughness,no single method can meet all the requirements.Finally,the future development prospects and application directions of different polishing technologies are presented.展开更多
Millets are widely recognized for their nutritional significance;however, the methods employed for their processing are currently lacking. This article primarily focuses on the advanced technologies and progressions i...Millets are widely recognized for their nutritional significance;however, the methods employed for their processing are currently lacking. This article primarily focuses on the advanced technologies and progressions in millet dehulling and polishing. These technologies operate based on the fundamental principles of compression-shearing, abrasion-friction, and centrifugal-impact forces. Processing of millets can be challenging because of the physical characteristics and tight attachment of hull and bran to the endosperm. However, several dehullers have been designed to solve this problem for different kinds of millets. In addition, the nutritional and anti-nutritional characteristics undergo alterations due to both dehulling and polishing processes. These alterations are thoroughly examined and discussed in this article. Specifically, anti-nutrients such as tannins and phytate are predominantly found in the outer pericarp of the grain and experience a reduction after undergoing dehulling and polishing. The nutritional properties are also subjected to a reduction;however, this reduction can be mitigated by subjecting the grains to certain pretreatments before dehulling and polishing. These treatments serve to enhance dehulling efficiency and nutrient digestibility while simultaneously reducing the presence of anti-nutrients. Novel thermal and non-thermal methodologies such as microwave, hydrothermal, high-pressure processing, and ohmic heating can be employed for processing millets, thereby diminishing the loss of nutrients. Additional research can be carried out to investigate their impact on the dehulling and polishing of millets.展开更多
This paper concerns the compactness and separability properties of the normed Boolean algebras (N.B.A.) with respect to topology generated by a distance equal to the square root of a measure of symmetric difference be...This paper concerns the compactness and separability properties of the normed Boolean algebras (N.B.A.) with respect to topology generated by a distance equal to the square root of a measure of symmetric difference between two elements. The motivation arises from studying random elements talking values in N.B.A. Those topological properties are important assumptions that enable us to avoid possible difficulties when generalising concepts of random variable convergence, the definition of conditional law and others. For each N.B.A., there exists a finite measure space ( E,ℰ,μ ) such that the N.B.A. is isomorphic to ( ℰ ˜ , μ ˜ ) resulting from the factorisation of initial σ-algebra by the ideal of negligible sets. We focus on topological properties ( ℰ ˜ , μ ˜ ) in general setting when μ can be an infinite measure. In case when μ is infinite, we also consider properties of ℰ ˜ fin ⊆ ℰ ˜ consisting of classes of measurable sets having finite measure. The compactness and separability of the N.B.A. are characterised using the newly defined terms of approximability and uniform approximability of the corresponding measure space. Finally, conditions on ( E,ℰ,μ ) are derived for separability and compactness of ℰ ˜ and ℰ ˜ fin .展开更多
The award-winning novel The Polished Hoe(2002),written by Austin Clarke,explores the way that black Caribbean females construct a radical identity by resisting sexual victimization and reach a complex understanding of...The award-winning novel The Polished Hoe(2002),written by Austin Clarke,explores the way that black Caribbean females construct a radical identity by resisting sexual victimization and reach a complex understanding of the self by simultaneously occupying various subject positions.This paper addresses Mary-Mathilda’s experiences of sexual exploitation and the reconstruction of her identity with the function of her black female body.Narratives of sexual violence,commodification and objectification of black female bodies in the patriarchal context are exposed through the intersectionality of the vectors of race,class and gender.The notion of performativity of the black female body comes to the forefront.What is innovative in this approach is that Mary-Mathilda’s body symbolizes disempowerment and empowerment simultaneously from the perspective of Peirce’s semiotic theory,juxtaposing within the multifaceted and nuanced subject positions she occupies.In addition,the definitional boundaries of the black female body are explored through a phenomenological approach.The transformation of Mary-Mathilda as radical subjects through subversive acts of agency is finally revealed in this paper.展开更多
Contemporary villages of the mountain region are subject to uncontrolled structural and spatial transformations,which cause deformation of centuries-old spatial systems of high cultural and natural value.The aim of th...Contemporary villages of the mountain region are subject to uncontrolled structural and spatial transformations,which cause deformation of centuries-old spatial systems of high cultural and natural value.The aim of the study is to confront the opinions of the inhabitants and experts regarding the condition of the cultural landscape of the villages in south-eastern Poland.This area belongs to the Carpathian region of Central Europe.The historical and economic conditions of the studied region,related to the functioning in the post-war period,and then its breakdown and the development of the free market economy,constitute an interesting background for the proposed research.Local communities still remembering the period of difficulties related to the period of systemic transformations,are currently experiencing a relative prosperity,many difficulties related to the period of systemic transformations,are currently experiencing a relative prosperity,which is also expressed in a completely new,previously unknown way of managing the landscape.Investments implemented in villages are associated by the inhabitants with the improvement of the standards and quality of life.They assess them rather positively.An expert assessment of these landscape transformations indicates their negative dimension and the risk of losing timeless values.The discrepancy in the assessment of experts and local residents creates difficulties in the protection of the rural landscape.Therefore,high-quality visual landscape features among rural residents is necessary from the point of view of its multi-faceted and effective protection.Local initiatives and actions in the field of industry policy should play a significant role in this respect by consolidating the images of a harmonious landscape in the public awareness.展开更多
The polishing efficiency of the soft abrasive flow(SAF)method is low,which is not in line with the concept of carbon emission reduction in industrial production.To address the above issue,a two-phase fluid multi-physi...The polishing efficiency of the soft abrasive flow(SAF)method is low,which is not in line with the concept of carbon emission reduction in industrial production.To address the above issue,a two-phase fluid multi-physics modeling method for ultrasonic-assisted SAF processing is proposed.The acoustics-fluid coupling mechanic model based on the realizable k-ε model and Helmholtz equation is built to analyze the cavitation effect.The results show that the pro-posed modeling and solution method oriented to ultrasonic-assisted SAF processing have better revealed the flow field evolution mechanism.The turbulence kinetic energy at different ultrasonic frequencies and amplitudes is stud-ied.Simulation results show that the ultrasonic vibration can induce a cavitation effect in the constrained flow chan-nel and promote the turbulence intensity and uniformity of the abrasive flow.A set of comparative polishing experiments with or without ultrasonic vibration are conducted to explore the performance of the proposed method.It can be found that the ultrasonic-assisted SAF method can improve the machining efficiency and uniformity,to achieve the purpose of carbon emission reduction.The relevant result can offer a helpful reference for the SAF method.展开更多
The process of wafer polishing is known to be highly demanding,and even small deviations in the processing parameters can have a significant impact on the quality of the wafers obtained.During the process of wafer pol...The process of wafer polishing is known to be highly demanding,and even small deviations in the processing parameters can have a significant impact on the quality of the wafers obtained.During the process of wafer polishing,maintaining a constant pressure value applied by the polishing head is essential to achieve the desired flatness of the wafer.The accuracy of the downward pressure output by the polishing head is a crucial factor in producing flat wafers.In this paper,the uncertainty component of downward pressure is calculated and its measurement uncertainty is evaluated,and a method for calculating downward pressure uncertainty traceable to international basic unit is established.Therefore,the reliability of double side polishing machine has been significantly improved.展开更多
In the international communist movement in the 19th century,the national uprising in Europe and the workers’movement were intertwined,forming a complex historical background.The Polish National Uprising in 1863 becam...In the international communist movement in the 19th century,the national uprising in Europe and the workers’movement were intertwined,forming a complex historical background.The Polish National Uprising in 1863 became a historical opportunity for the establishment of the First International.Although the unity of the British workers and the French workers was the realistic basis of the First International,the French workers showed a vague attitude different from the British workers on the Polish issue.In the first Congress of the First International,the French workers who almost are Proudhonists rejected the issue of supporting the Polish nation against the Tsar Russian oppression.Pierre-Joseph Proudhon did not link the Polish issue with the workers’movement,while he insisted that social and economic issues should not be confused with political reconstruction,and artificially separated national revival from workers’liberation.In order to promote and assist the establishment of the First International,Marx made certain consideration and concessions on national issues in the formulation of its declaration and constitution.Then Engels,commissioned by Marx,made some specific interpretations that they based on the difference between nation and nationality,and adhere it to the international national principle,both clearly shows the Marxism view of nation state,reveals the risk if international communist movement limited to the principle of nationalities,and also further reveals the importance to combine two great cause,national revival and workers liberation.展开更多
文摘PINGYAO hand-polished lacquerware has been widely considered as one of the four most famed lacquerware types in China.It originated more than 2,000 years ago in what is called Pingyao County today,in Jinzhong City,central China’s Shanxi Province.Its fame is due to the exquisite and unique skill of polishing lacquered coating with bare hands during the manufacturing process.This quaint and durable lacquerware boasts both aesthetic and practical values,and is characterized by its distinguished appearance and glossy sheen.It comes in the forms of jewelry boxes,utensils and stationery,screens and furniture.
基金The authors are thankful to Rice Research Centres of Anantnag and Kupwara,J&K for helping us in getting paddy.
文摘The present investigation was aimed to study functional properties,antioxidant activity and in-vitro digestibility characteristics of brown and polished flours obtained from four rice cultivars(SR-4,K-39,Mushq Budij and Zhag)of Kashmir.Brown rice flours had higher total dietary fibre(3.08%-3.68%),oil absorption(116.0%-139.0%),emulsion capacity(4.78%-9.52%),emulsion stability(87.46%-99.93%)and resistant starch content(6.80%-9.00%)than polished flours.However,polished flours presented greater water absorption(102.0%-122.0%),foaming capacity(8.00%-13.63%),apparent amylose(19.16%-22.62%),peak(2260.0-2408.0 cP),trough(1372.0-1589.0 cP)and breakdown(714.0-978.0 cP)viscosities than their brown counterparts.Brown rice flours depicted highest total phenolic content(4.40-6.40 mg GAE/g)and inhibition of lipid peroxidation(19.50%-33.20%).However,equilibrium starch hydrolysis percentage(C∞)and predicted glycemic index of brown rice flours were lower than their polished counterparts.Among rice cultivars,brown Zhag flour had the highest total dietary fibre(3.68%),emulsion capacity(9.52%),emulsion stability(99.93%),resistant starch(9.00%),DPPH radical scavenging activity(85.45%)and inhibition of lipid peroxidation(33.20%),respectively.Emulsion capacity and emulsion stability were positively correlated with protein content of rice flours.However,peak,trough,breakdown and setback viscosities were negatively correlated with protein and fat contents of rice flour.The present investigation will be helpful in identifying nutritive role of rice flours from studied cultivars in human diet.
基金National Natural Science Foundation of China(No.61405127)Shanxi Province Science Foundation for Youths(No.2014021023-1)+1 种基金Scientific and Technologial Innovation Programs of Higher Education Institutions in Shanxithe Program for Top Young Academic Leaders of Higher Learning Institutions of Shanxi
文摘Transmission characteristics of the side polished fiber were studied by experimental method.The side polished fibers with different depth and length were implemented,and the corresponding wavelength dependent loss was measured.Based on wheel fabrication,the side polished fibers were achieved with the low insertion loss and cost.Meanwhile,they can be artificially controlled for the use of evanescent field area and easy to system integration.
基金supported by the National Natural Science Foundation of China under Grant No. 10776009 and 60877044Science and Technology Projects of Guangzhou Province, China under Grant No. 2007Z2-D0091Natural Science Foundation of Guangdong Province under Grant No. 7300084.
文摘The performance of optical power transmission through a side-polished fiber on which materials of different refractive indices were overlaid is investigated. The experiments show that the transmitted optical power through the side-polished fiber varies with the refractive index of the overlaid material. The result of our experiments fits well the theoretical calculation. Side-polished fiber manufactured by wheel polishing method can be used not only to control optical power transmission through the fiber core but also as a refractive index sensor.
文摘The etching technique using Ce is a convenient and fast method for polishing and shaping diamond films. In this study, the influence of polishing parameters such as polishing temperature and time on the surface crystallinity and phase composition of diamond films was thoroughly investigated via the analysis of Raman spectra such as FWHM and ID/IG. Moreover, the issue on the graphitization of diamond after polishing with Ce was further researched through the detailed study of the depth distribution of Raman data including FWHM and ID/IG, and a result completely different from the hot-iron metal polished ones was obtained. The results showed that polished diamond films had considerably higher diamond content than those before polishing, and not a bit of graphitization was found in the polished ones, owing to a higher solubility of carbon in rare earth metal Ce than that in transition metals, and the original crystallinity of the films polished with Ce did not deteriorate.
文摘This paper mainly focuses on the influence of colloidal silica polishing on the damage performance of fused silica optics. In this paper, nanometer sized colloidal silica and micron sized ceria are used to polish fused silica optics. The colloidal silica polished samples and ceria polished samples exhibit that the root-mean-squared (RMS) average surface roughness values are 0.7 nm and 1.0 rim, respectively. The subsurface defects and damage performance of the polished optics are analyzed and discussed. It is revealed that colloidal silica polishing will introduce much fewer absorptive con- taminant elements and subsurface damages especially no trailing indentation fracture. The 355-nm laser damage test reveals that each of the fused silica samples polished with colloidal silica has a much higher damage threshold and lower damage density than ceria polished samples. Colloidal silica polishing is potential in manufacturing high power laser optics.
基金Projects(51305450,51275521)supported by the National Natural Science Foundation of China
文摘Removal of brittle materials in the brittle or ductile mode inevitably causes damaged or strained surface layers containing cracks, scratches or dislocations. Within elastic deformation, the arrangement of each atom can be recovered back to its original position without any defects introduced. Based on surface hydroxylation and chemisorption theory, material removal mechanism of quartz glass in the elastic mode is analyzed to obtain defect-free surface. Elastic contact condition between nanoparticle and quartz glass surface is confirmed from the Hertz contact theory model. Atoms on the quartz glass surface are removed by chemical bond generated by impact reaction in the elastic mode, so no defects are generated without mechanical process. Experiment was conducted on a numerically controlled system for nanoparticle jet polishing, and one flat quartz glass was polished in the elastic mode. Results show that scratches on the sample surface are completely removed away with no mechanical defects introduced, and microroughness(Ra) is decreased from 1.23 nm to 0.47 nm. Functional group Ce — O — Si on ceria nanoparticles after polishing was detected directly and indirectly by FTIR, XRD and XPS spectra analysis from which the chemical impact reaction is validated.
文摘Purpose: Bacterial adhesion represents the initial step in biofilm formation, dental caries and decay. This study aimed to evaluate and compare surface roughness and bacterial adhesion to bulk fill resin composites polished with different systems. Methods: Filtek Z350 XT (Incremental-fill resin composite), Filtek Bulk-fill Posterior (Bulk-fill resin composite), and Tetric N Ceram (Bulk-fill resin composite) were used as resin composites. The polishing systems used in this study were Sof-Lex multi-step, PoGo one step, and Mylar strip. Scanning electron microscope (SEM) was used to examine the surface roughness and adhesion of Streptococcus mutans ATCC 25175 standard strain to bulk-fill resin composites. Results: The type of restorative materials did not affect the surface roughness or bacterial adhesion (p > 0.05) but the polishing systems were significant (p R = 0.943) between surface roughness and bacterial adhesion to the tested surfaces. Conclusion: Regardless of the restorative material, Mylar polishing system revealed the smoothest surface and the lowest adhesion of S. mutans as compared to Pogo one step and Sof-Lex multi-step polishing systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174155,61705086,61675092,and 62075088)National Key Research and Development Program of China(Grant Nos.2021YFB2800801 and 2018YFB1801900)+7 种基金Natural Science Foundation of Guangdong Province for Distinguished Young Scholar(Grant No.2020B1515020024)Natural Science Foundation of Guangdong Province(Grant Nos.2017A030313375and 2019A1515011380)Key-Area Research and Development Program of Guangdong Province(Grant No.2019B010138004)Project of Guangzhou Industry Leading Talents(Grant No.CXLJTD-201607)Aeronautical Science Foundation of China(Grant Nos.201708W4001 and 201808W4001)Project of STRPAT of EC Laboratory(Grant No.ZHD201902)TESTBED2(Grant No.H2020-MSCA-RISE-2019)Jinan Outstanding Young Scholar Support Program(Grant Nos.JNSBYC-2020040 and JNSBYC-2020117).
文摘Side polished fiber(SPF)has a controllable average roughness and length of the side-polishing region,which becomes a versatile platform for integrating multiple materials to interact with the evanescent field to fabricate all-fiber devices and sensors.It has been widely used in couplers,filters,polarizers,optical attenuators,photodetectors,modulators,and sensors for temperature,humidity,strain,biological molecules,chemical gas,and vector magnetic monitoring.In this article,an overview of the development history,fabrication techniques,fiber types,transmission characteristics,and varied recent applications of SPFs are reviewed.Firstly,the fabrication techniques of SPFs are reviewed,including the V-groove assisted polishing technique and wheel polishing technique.Then,the different types of SPFs and their characteristics are discussed.Finally,various applications of SPFs are discussed and concluded theoretically and experimentally,including their principles and structures.When designing the device,the residual thickness and polishing lengths of the SPF need to be appropriately selected in order to obtain the best performance.Developing all-fiber devices and sensors is aimed at practical usability under harsh environments and allows to avoid the high coupling loss between optical fibers and on-chip integrated devices.
基金the National Key Research and Development Program of China(2018YFA0703400)the Young Scientists Fund of the National Natural Science Foundation of China(52205447)Changjiang Scholars Program of the Chinese Ministry of Education。
文摘It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm.Traditional polishing methods are disabled to polish the component,meanwhile keeping the structure intact.To overcome this challenge,small-grooved components made of aluminum alloy with sizes less than 1 mm were fabricated by a custom-made printer.A novel approach to multi-phase jet(MPJ)polishing is proposed,utilizing a self-developed polisher that incorporates solid,liquid,and gas phases.In contrast,abrasive air jet(AAJ)polishing is recommended,employing a customized polisher that combines solid and gas phases.After jet polishing,surface roughness(Sa)on the interior surface of grooves decreases from pristine 8.596μm to 0.701μm and 0.336μm via AAJ polishing and MPJ polishing,respectively,and Sa reduces 92%and 96%,correspondingly.Furthermore,a formula defining the relationship between linear energy density and unit defect volume has been developed.The optimized parameters in additive manufacturing are that linear energy density varies from 0.135 J mm^(-1)to 0.22 J mm^(-1).The unit area defect volume achieved via the optimized parameters decreases to 1/12 of that achieved via non-optimized ones.Computational fluid dynamics simulation results reveal that material is removed by shear stress,and the alumina abrasives experience multiple collisions with the defects on the heat pipe groove,resulting in uniform material removal.This is in good agreement with the experimental results.The novel proposed setups,approach,and findings provide new insights into manufacturing complex-structured components,polishing the small-grooved structure,and keeping it unbroken.
基金Supported by Research Grants Council of the Government of the Hong Kong Special Administrative Region of China (Grant No.15203620)Research and Innovation Office of The Hong Kong Polytechnic University of China (Grant Nos.BBXN,1-W308)+1 种基金Research Studentships (Grant No.RH3Y)State Key Laboratory of Mechanical System and Vibration of China (Grant No.MSV202315)。
文摘Ceramic cutting inserts are a type of cutting tool commonly used in high-speed metal cutting applications.However,the wear of these inserts caused by friction between the workpiece and cutting inserts limits their overall effectiveness.In order to improve the tool life and reduce wear,this study introduces an emerging method called magnetic field-assisted batch polishing(MABP)for simultaneously polishing multiple ceramic cutting inserts.Several polishing experiments were conducted under different conditions,and the wear characteristics were clarified by cutting S136H steel.The results showed that after 15 min of polishing,the surface roughness at the flank face,edge,and nose of the inserts was reduced to below 2.5 nm,6.25 nm,and 45.8 nm,respectively.Furthermore,the nose radii of the inserts did not change significantly,and there were no significant changes in the weight percentage of elements before and after polishing.Additionally,the tool life of the batch polished inserts was found to be up to 1.75 times longer than that of unpolished inserts.These findings suggest that the MABP method is an effective way to mass polish ceramic cutting inserts,resulting in significantly reduced tool wear.Furthermore,this novel method offers new possibilities for polishing other tools.
基金the support from the National Key Research and Development Program of China[2018YFA0703400].
文摘The infrared conformal window is one of the most critical components in aircraft.Conformal windows with high performance bring low aberrations,high aerodynamic performance,reliability in extreme working environments,and added value for aircraft.Through the past decades,remarkable advances have been achieved in manufacturing technologies for conformal windows,where the machining accuracy approaches the nanometer level,and the surface form becomes more complex.These advances are critical to aircraft development,and these manufacturing technologies also have significant reference values for other directions of the ultra-precision machining field.In this review,the infrared materials suitable for manufacturing conformal windows are introduced and compared with insights into their performances.The remarkable advances and concrete work accomplished by researchers are reviewed.The challenges in manufacturing conformal windows that should be faced in the future are discussed.
基金sponsored by the National Natural Science Foundation of China(Nos.51835004,U22A20198)the Major Science and Technology Projects in Henan Province(221100230300)the 111 Project(No.B23011)。
文摘Diamond is a highly valuable material with diverse industrial applications,particularly in the fields of semiconductor,optics,and high-power electronics.However,its high hardness and chemical stability make it difficult to realize high-efficiency and ultra-low damage machining of diamond.To address these challenges,several polishing methods have been developed for both single crystal diamond(SCD)and polycrystalline diamond(PCD),including mechanical,chemical,laser,and ion beam processing methods.In this review,the characteristics and application scope of various polishing technologies for SCD and PCD are highlighted.Specifically,various energy beam-based direct and assisted polishing technologies,such as laser polishing,ion beam polishing,plasma-assisted polishing,and laser-assisted polishing,are summarized.The current research progress,material removal mechanism,and infuencing factors of each polishing technology are analyzed.Although some of these methods can achieve high material removal rates or reduce surface roughness,no single method can meet all the requirements.Finally,the future development prospects and application directions of different polishing technologies are presented.
基金the Indian Institute of Technology, Kharagpur, West Bengal, 721302, for providing technical and financial support for the research。
文摘Millets are widely recognized for their nutritional significance;however, the methods employed for their processing are currently lacking. This article primarily focuses on the advanced technologies and progressions in millet dehulling and polishing. These technologies operate based on the fundamental principles of compression-shearing, abrasion-friction, and centrifugal-impact forces. Processing of millets can be challenging because of the physical characteristics and tight attachment of hull and bran to the endosperm. However, several dehullers have been designed to solve this problem for different kinds of millets. In addition, the nutritional and anti-nutritional characteristics undergo alterations due to both dehulling and polishing processes. These alterations are thoroughly examined and discussed in this article. Specifically, anti-nutrients such as tannins and phytate are predominantly found in the outer pericarp of the grain and experience a reduction after undergoing dehulling and polishing. The nutritional properties are also subjected to a reduction;however, this reduction can be mitigated by subjecting the grains to certain pretreatments before dehulling and polishing. These treatments serve to enhance dehulling efficiency and nutrient digestibility while simultaneously reducing the presence of anti-nutrients. Novel thermal and non-thermal methodologies such as microwave, hydrothermal, high-pressure processing, and ohmic heating can be employed for processing millets, thereby diminishing the loss of nutrients. Additional research can be carried out to investigate their impact on the dehulling and polishing of millets.
文摘This paper concerns the compactness and separability properties of the normed Boolean algebras (N.B.A.) with respect to topology generated by a distance equal to the square root of a measure of symmetric difference between two elements. The motivation arises from studying random elements talking values in N.B.A. Those topological properties are important assumptions that enable us to avoid possible difficulties when generalising concepts of random variable convergence, the definition of conditional law and others. For each N.B.A., there exists a finite measure space ( E,ℰ,μ ) such that the N.B.A. is isomorphic to ( ℰ ˜ , μ ˜ ) resulting from the factorisation of initial σ-algebra by the ideal of negligible sets. We focus on topological properties ( ℰ ˜ , μ ˜ ) in general setting when μ can be an infinite measure. In case when μ is infinite, we also consider properties of ℰ ˜ fin ⊆ ℰ ˜ consisting of classes of measurable sets having finite measure. The compactness and separability of the N.B.A. are characterised using the newly defined terms of approximability and uniform approximability of the corresponding measure space. Finally, conditions on ( E,ℰ,μ ) are derived for separability and compactness of ℰ ˜ and ℰ ˜ fin .
文摘The award-winning novel The Polished Hoe(2002),written by Austin Clarke,explores the way that black Caribbean females construct a radical identity by resisting sexual victimization and reach a complex understanding of the self by simultaneously occupying various subject positions.This paper addresses Mary-Mathilda’s experiences of sexual exploitation and the reconstruction of her identity with the function of her black female body.Narratives of sexual violence,commodification and objectification of black female bodies in the patriarchal context are exposed through the intersectionality of the vectors of race,class and gender.The notion of performativity of the black female body comes to the forefront.What is innovative in this approach is that Mary-Mathilda’s body symbolizes disempowerment and empowerment simultaneously from the perspective of Peirce’s semiotic theory,juxtaposing within the multifaceted and nuanced subject positions she occupies.In addition,the definitional boundaries of the black female body are explored through a phenomenological approach.The transformation of Mary-Mathilda as radical subjects through subversive acts of agency is finally revealed in this paper.
文摘Contemporary villages of the mountain region are subject to uncontrolled structural and spatial transformations,which cause deformation of centuries-old spatial systems of high cultural and natural value.The aim of the study is to confront the opinions of the inhabitants and experts regarding the condition of the cultural landscape of the villages in south-eastern Poland.This area belongs to the Carpathian region of Central Europe.The historical and economic conditions of the studied region,related to the functioning in the post-war period,and then its breakdown and the development of the free market economy,constitute an interesting background for the proposed research.Local communities still remembering the period of difficulties related to the period of systemic transformations,are currently experiencing a relative prosperity,many difficulties related to the period of systemic transformations,are currently experiencing a relative prosperity,which is also expressed in a completely new,previously unknown way of managing the landscape.Investments implemented in villages are associated by the inhabitants with the improvement of the standards and quality of life.They assess them rather positively.An expert assessment of these landscape transformations indicates their negative dimension and the risk of losing timeless values.The discrepancy in the assessment of experts and local residents creates difficulties in the protection of the rural landscape.Therefore,high-quality visual landscape features among rural residents is necessary from the point of view of its multi-faceted and effective protection.Local initiatives and actions in the field of industry policy should play a significant role in this respect by consolidating the images of a harmonious landscape in the public awareness.
基金Supported by National Natural Science Foundation of China(Grant No.52175124)Zhejiang Provincial Natural Science Foundation(Grant No.LZ21E050003)Fundamental Research Funds for the Zhejiang Universities(Grant No.RF-C2020004).
文摘The polishing efficiency of the soft abrasive flow(SAF)method is low,which is not in line with the concept of carbon emission reduction in industrial production.To address the above issue,a two-phase fluid multi-physics modeling method for ultrasonic-assisted SAF processing is proposed.The acoustics-fluid coupling mechanic model based on the realizable k-ε model and Helmholtz equation is built to analyze the cavitation effect.The results show that the pro-posed modeling and solution method oriented to ultrasonic-assisted SAF processing have better revealed the flow field evolution mechanism.The turbulence kinetic energy at different ultrasonic frequencies and amplitudes is stud-ied.Simulation results show that the ultrasonic vibration can induce a cavitation effect in the constrained flow chan-nel and promote the turbulence intensity and uniformity of the abrasive flow.A set of comparative polishing experiments with or without ultrasonic vibration are conducted to explore the performance of the proposed method.It can be found that the ultrasonic-assisted SAF method can improve the machining efficiency and uniformity,to achieve the purpose of carbon emission reduction.The relevant result can offer a helpful reference for the SAF method.
文摘The process of wafer polishing is known to be highly demanding,and even small deviations in the processing parameters can have a significant impact on the quality of the wafers obtained.During the process of wafer polishing,maintaining a constant pressure value applied by the polishing head is essential to achieve the desired flatness of the wafer.The accuracy of the downward pressure output by the polishing head is a crucial factor in producing flat wafers.In this paper,the uncertainty component of downward pressure is calculated and its measurement uncertainty is evaluated,and a method for calculating downward pressure uncertainty traceable to international basic unit is established.Therefore,the reliability of double side polishing machine has been significantly improved.
文摘In the international communist movement in the 19th century,the national uprising in Europe and the workers’movement were intertwined,forming a complex historical background.The Polish National Uprising in 1863 became a historical opportunity for the establishment of the First International.Although the unity of the British workers and the French workers was the realistic basis of the First International,the French workers showed a vague attitude different from the British workers on the Polish issue.In the first Congress of the First International,the French workers who almost are Proudhonists rejected the issue of supporting the Polish nation against the Tsar Russian oppression.Pierre-Joseph Proudhon did not link the Polish issue with the workers’movement,while he insisted that social and economic issues should not be confused with political reconstruction,and artificially separated national revival from workers’liberation.In order to promote and assist the establishment of the First International,Marx made certain consideration and concessions on national issues in the formulation of its declaration and constitution.Then Engels,commissioned by Marx,made some specific interpretations that they based on the difference between nation and nationality,and adhere it to the international national principle,both clearly shows the Marxism view of nation state,reveals the risk if international communist movement limited to the principle of nationalities,and also further reveals the importance to combine two great cause,national revival and workers liberation.