Our recent archaeological expeditions in the Siuyu and Ughaugha wards of Singida eastern province have recuperated the very compelling rock engravings (petroglyphs) that weren’t reported in Tanzania before. Archaeolo...Our recent archaeological expeditions in the Siuyu and Ughaugha wards of Singida eastern province have recuperated the very compelling rock engravings (petroglyphs) that weren’t reported in Tanzania before. Archaeologically, Singida’s fame emanated from her endowments of rock paintings. However;during this research, we did discover rock cupules, gongs, and grinding hollows art together with rock paintings (pictographs) that have opened up a new avenue for rock art studies in Tanzania. We carried out intensive site surveys around four sites namely Siuyu, Ngaghe, Misimbwa and Ughaugha B with the aims of solely examining, recording, and documenting archaeological artifacts on the surface in order to research the cultural and behavioural patterns of early humans in the Singida region. Surveys also enabled us to locate suitable areas where future excavations would be established. In some cases, ethnographic enquiries were employed to get supplementary information on the present-day use of rock art sites. Besides, we interviewed local people to assess their general understanding of the presence of more sites or helping in locating, and discovering new sites. Through ethnographic inquiries, we discovered several sites with substantial number of rock engravings that were never document by any researcher. On top of that, this study reports other archaeological potentials of the region by describing in detail their significances for future research undertakings. Additionally, this paper article reports on the occurrence of Middle Stone Age (MSA) archaeological assemblages from the open-air site and the presence of grinding hollows and rock cupules (Siuyu complexes) in central Tanzania for the first time.展开更多
By combining with an improved model on engraving process,a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators.Using comput...By combining with an improved model on engraving process,a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators.Using computational fluid dynamics(CFD),the two-phase flow and piston engraving characteristics of a pyrotechnic actuator are investigated.Initially,the current model was utilized to examine the intricate,multi-dimensional flow,and energy conversion characteristics of the propellant grains and combustion gas within the pyrotechnic actuator chamber.It was discovered that the combustion gas on the wall's constant transition from potential to kinetic energy,along with the combined effect of the propellant motion,are what create the pressure oscillation within the chamber.Additionally,a numerical analysis was conducted to determine the impact of various parameters on the pressure oscillation and piston motion,including pyrotechnic charge,pyrotechnic particle size,and chamber structural dimension.The findings show that decreasing the pyrotechnic charge will lower the terminal velocity,while increasing and decreasing the pyrotechnic particle size will reduce the pressure oscillation in the chamber.The pyrotechnic particle size has minimal bearing on the terminal velocity.The results of this investigation offer a trustworthy forecasting instrument for comprehending and creating pyrotechnic actuator designs.展开更多
The origin of engraving and printing has a variety of points of view,especially the“early Tang Dynasty”has the most far-reaching impact.Based on media evolution theory,engraved printing as a new media technology is ...The origin of engraving and printing has a variety of points of view,especially the“early Tang Dynasty”has the most far-reaching impact.Based on media evolution theory,engraved printing as a new media technology is first used in secular culture,folk entertainment,and other fields,after a long period of development,the new medium was accepted by the ruling class,the mainstream society;the use of the media began to intervene in the real society.This reflects that the choice of new media by the society depends on the media itself and is intrinsically linked to the whole social communication environment.Therefore,from the point of view of media evolution,the view that engraving originated in the early Tang Dynasty is not in line with the logic of media evolution and is unreasonable.展开更多
The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational eff...The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.展开更多
Classical Chinese characters,presented through calligraphy,seal engraving,or painting,can exhibit different aesthetics and essences of Chinese characters,making them the most important asset of the Chinese people.Call...Classical Chinese characters,presented through calligraphy,seal engraving,or painting,can exhibit different aesthetics and essences of Chinese characters,making them the most important asset of the Chinese people.Calligraphy and seal engraving,as two closely related systems in traditional Chinese art,have developed through the ages.Due to changes in lifestyle and advancements in modern technology,their original functions of daily writing and verification have gradually diminished.Instead,they have increasingly played a significant role in commercial art.This study utilizes the Evaluation Grid Method(EGM)and the Analytic Hierarchy Process(AHP)to research the key preference factors in the application of calligraphy and seal engraving imagery.Different from the traditional 5-point equal interval semantic questionnaire,this study employs a non-equal interval semantic questionnaire with a golden ratio scale,distinguishing the importance ratio of adjacent semantic meanings and highlighting the weighted emphasis on visual aesthetics.Additionally,the study uses Importance-Performance Analysis(IPA)and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)to obtain the key preference sequence of calligraphy and seal engraving culture.Plus,the Choquet integral comprehensive evaluation is used as a reference for IPA comparison.It is hoped that this study can provide cultural imagery references and research methods,injecting further creativity into industrial design.展开更多
Lavinia Fontana’s(1552-1614)Galatea and Cherubs riding the Stormy Waves on a Sea Monster(aka Galatea)of 1590 is an intriguing mythological painting.Being painted on copper,it is a fine example of Lavinia’s explorati...Lavinia Fontana’s(1552-1614)Galatea and Cherubs riding the Stormy Waves on a Sea Monster(aka Galatea)of 1590 is an intriguing mythological painting.Being painted on copper,it is a fine example of Lavinia’s exploration of new artistic techniques and materials as well as testimony to her bold artistic interpretations.Lavinia’s Galatea was part of a private collection in Bologna(Diletta Badeschi).This work fascinates the viewer with its erotic audacity and complex iconographical conceits.Recent scholarship by Daniele Benati,Fausto Gozzi,and Enrico Maria Dal Pozzolo assist in unraveling the meaning of this painting.In this essay there are additional interpretative suggestions.展开更多
Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most...Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.展开更多
Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practic...Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.展开更多
Microfluidic solvent extraction （micro SX） of gadolinium was conducted using a mono- and diester mixture （MDEHPA） as the cationic extractant. A microfluidic Y-Y channel was fabricated using CO2- laser technique in...Microfluidic solvent extraction （micro SX） of gadolinium was conducted using a mono- and diester mixture （MDEHPA） as the cationic extractant. A microfluidic Y-Y channel was fabricated using CO2- laser technique in a glass microchip used as the extraction system. Compared with batch extraction, extraction kinetic is found fast, and extraction equilibrium is attained within 15 s. Stoichiometry of the extracted complex is found to be Gd（NOs）3-3MDEHPA using log-log plot method. Additionally, the operating parameters and overall volumetric mass transfer coefficient （kLα） were investigated to determine the mass transfer performance. Optimal condition of microextraction for gadolinium using response surface methodology was determined （feed solutions 31 mg/L adjusted to pH value 2.5, extractant concentration 2.9 vol% and extraction time 13.5 s）. In optimal condition, gadolinium extraction yield is obtained 95.5%. Findings of this study approve simplicity, portability, effectiveness, swiftness, and environmental friendliness microfluidic solvent extraction process and reveal that micro SX is useful in the field of extraction strategic metals present at low concentrations, which are otherwise not technically amenable or economically feasible to extract using current traditional methods.展开更多
Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space met...Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space method. The test results of representative samples show that the resonance frequencies and the resonance peak or valley values in two polarization modes are not completely identical but the differentials are small, indicating that the influences of polarization modes are not significant. The transmission coefficient curves of Y-shaped and Y-ring-shaped FSFs with various size parameters are obviously different. For instance, as the unit size D increases by 4.0 mm, the resonance frequencies of patch FSFs decrease by 1.92 GHz and the resonance valleys increase by 12.32 dB. Different size parameters have dissimilar effects on the transmission characteristics and the corresponding influence laws should be analyzed concretely. The work could provide reference for the structural design and characteristics analysis of other FSFs.展开更多
This paper researches the main technology of open CNC engraving machine, the DXF identification technology. Agraphic information extraction method is proposed. By this method, the graphic information in DXF file can b...This paper researches the main technology of open CNC engraving machine, the DXF identification technology. Agraphic information extraction method is proposed. By this method, the graphic information in DXF file can be identified and transformed into bottom motion controller’s code. So the engraving machine can achieve trajectory tracking. Then the open CNC engraving machine system is developed with C#. At last, the method is validated on a three axes motion experiment platform. The result shows that this method can efficiently identify the graphic information including line, circle, arc etc. in DXF file and the CNC engraving machine can be controlled well.展开更多
The art of seal en graving is a comerstone of Chinese fine arts. The seal was originally used as a signature or sign of authority, but it came to be used by all social classes and in much of Asia. The Seal *Engravers ...The art of seal en graving is a comerstone of Chinese fine arts. The seal was originally used as a signature or sign of authority, but it came to be used by all social classes and in much of Asia. The Seal *Engravers Society of Xiling in east China's Zhejiang Province, which was founded a century ago, preserves the art of seal engraving along with approximately 100 other specialized institutions. The design is first sketched on paper, and then engraved on stone, in reverse, with a knife.展开更多
This paper uses the method of field research and consulting relevant materials, and then makes an orderly arrangement of the portraits and carvings of the Han Dynasty in China, which contain sports-related content, an...This paper uses the method of field research and consulting relevant materials, and then makes an orderly arrangement of the portraits and carvings of the Han Dynasty in China, which contain sports-related content, and further analyzes the Chinese national sports spirit that it shows. The military sports pain depicted in the Han Dynasty's portrait carvings shows the ancient Chinese people's strong and resolute patriotism of looking forward to a peaceful life, pledging to defend their own country, fighting bravely against foreign invaders;Competitive sports show the spirit of indomitable competitive sports and the courage to bear hardships. Sports health care shows the core spirit that people attach importance to health care and cherish life during the Han Dynasty. The sports with myths and legends and ghosts and gods as the main core contents show the Han people's spirit of advocating martial arts, pioneering bravely and fearless of nature and difficulties. However, people engaged in opera, music, dance and figure carving show the sports spirit of the Chinese people in the Han Dynasty, who were full of confidence, positive, bold in innovation and challenging various difficulties.展开更多
OVER 2,000 years ago,the bronze craftsmen in today’s Datong City,Shanxi Province,had already mastered the superb skills of copper production.Datong bronze-making craft was included in China’s state-level intangible ...OVER 2,000 years ago,the bronze craftsmen in today’s Datong City,Shanxi Province,had already mastered the superb skills of copper production.Datong bronze-making craft was included in China’s state-level intangible cultural heritage list in 2014.The craftsmanship which has been passed down through the millennia still shines brightly today after countless hammer blows and engravings.展开更多
The shear characteristics of the interface formed between a cemented tailings backfill(CTB)and surrounding rocks play a cru-cial role in the design and stability of underground goafs.To investigate the shear behavior ...The shear characteristics of the interface formed between a cemented tailings backfill(CTB)and surrounding rocks play a cru-cial role in the design and stability of underground goafs.To investigate the shear behavior of CTB-rock interfaces,rock samples repres-enting the topography of surrounding rocks were constructed using 3D morphology scanning and engraving techniques.A series of direct shear tests were conducted on the CTB rock samples to examine the influence of the cement-tailings ratio on the interfacial shear behavi-or.The results showed that the compressive strength of the CTB and shear strength of the CTB-rock interface decreased with decreasing cement proportion.With deceasing cement content,the failure area of the CTB after the test increased,and the roughness of the newly generated interface reduced.A digital image correlation analysis revealed that the compressive stress concentration in the region with an obtuse angle with respect to the shear direction was the primary cause of CTB failure.Moreover,the correlation between the wear area and the silicon-dense area helped confirm that the silicon particles are more prone to failure in these areas than in other regions.Our find-ings provide new insights into the shear sliding mechanism at CTB-rock interfaces and can aid in the selection of the cement-tailings ra-tio at engineering sites.For example,if the horizontal principal stress of the surrounding rock mass in a backfilling area is relatively high,the cement content can be reduced for CTB applications.展开更多
The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research t...The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research topic.To address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving process.In addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving process.By comparing with test data,the simulation accuracy of the coupled dynamics model is verified.Simulation results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not instantaneous.The results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.展开更多
The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great impor...The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great importance from the viewpoints of optimal design,manufacturing,use,and maintenance of gun and projectile.In this paper,the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi‐static and dynamic loading conditions.The quasi‐static engraving tests were performed on a CSS‐88500 electronic universal testing machine(EUTM)and a special gas‐gun‐based test rig was designed for dynamic impact engraving of the rotating bands.The mechanical behaviors of copper and nylon were investigated under strain rates of 10^(−3) s^(−1) and 2×10^(3) s^(−1) using an MTS 810 and a split Hopkinson pressure bar(SHPB),respectively.Morphologies of the worn surfaces and cross‐sectional microstructures were observed with scanning electron microscope(SEM)and optical microscope(OM).It was found that large deformation and severe friction occur during engraving.The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface.The structure of the rotating band and gun bore,band material,and loading rate have great effects on band engraving.The flow stress‐strain of the copper strongly depends on the applied strain rate.It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.展开更多
文摘Our recent archaeological expeditions in the Siuyu and Ughaugha wards of Singida eastern province have recuperated the very compelling rock engravings (petroglyphs) that weren’t reported in Tanzania before. Archaeologically, Singida’s fame emanated from her endowments of rock paintings. However;during this research, we did discover rock cupules, gongs, and grinding hollows art together with rock paintings (pictographs) that have opened up a new avenue for rock art studies in Tanzania. We carried out intensive site surveys around four sites namely Siuyu, Ngaghe, Misimbwa and Ughaugha B with the aims of solely examining, recording, and documenting archaeological artifacts on the surface in order to research the cultural and behavioural patterns of early humans in the Singida region. Surveys also enabled us to locate suitable areas where future excavations would be established. In some cases, ethnographic enquiries were employed to get supplementary information on the present-day use of rock art sites. Besides, we interviewed local people to assess their general understanding of the presence of more sites or helping in locating, and discovering new sites. Through ethnographic inquiries, we discovered several sites with substantial number of rock engravings that were never document by any researcher. On top of that, this study reports other archaeological potentials of the region by describing in detail their significances for future research undertakings. Additionally, this paper article reports on the occurrence of Middle Stone Age (MSA) archaeological assemblages from the open-air site and the presence of grinding hollows and rock cupules (Siuyu complexes) in central Tanzania for the first time.
基金supported by the National Natural Science Foundation of China(Grant No.11972194).
文摘By combining with an improved model on engraving process,a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators.Using computational fluid dynamics(CFD),the two-phase flow and piston engraving characteristics of a pyrotechnic actuator are investigated.Initially,the current model was utilized to examine the intricate,multi-dimensional flow,and energy conversion characteristics of the propellant grains and combustion gas within the pyrotechnic actuator chamber.It was discovered that the combustion gas on the wall's constant transition from potential to kinetic energy,along with the combined effect of the propellant motion,are what create the pressure oscillation within the chamber.Additionally,a numerical analysis was conducted to determine the impact of various parameters on the pressure oscillation and piston motion,including pyrotechnic charge,pyrotechnic particle size,and chamber structural dimension.The findings show that decreasing the pyrotechnic charge will lower the terminal velocity,while increasing and decreasing the pyrotechnic particle size will reduce the pressure oscillation in the chamber.The pyrotechnic particle size has minimal bearing on the terminal velocity.The results of this investigation offer a trustworthy forecasting instrument for comprehending and creating pyrotechnic actuator designs.
基金the National Social Science Foundation of China’s Art Program“Study on the Transformation of Tang and Song Calligraphy through the Perspective of Media Change and Engraved Plate Printing”(Project No.2020BF00876).
文摘The origin of engraving and printing has a variety of points of view,especially the“early Tang Dynasty”has the most far-reaching impact.Based on media evolution theory,engraved printing as a new media technology is first used in secular culture,folk entertainment,and other fields,after a long period of development,the new medium was accepted by the ruling class,the mainstream society;the use of the media began to intervene in the real society.This reflects that the choice of new media by the society depends on the media itself and is intrinsically linked to the whole social communication environment.Therefore,from the point of view of media evolution,the view that engraving originated in the early Tang Dynasty is not in line with the logic of media evolution and is unreasonable.
基金supported by the National Natural Science Foundation of China (Grant Number:12372093)。
文摘The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.
文摘Classical Chinese characters,presented through calligraphy,seal engraving,or painting,can exhibit different aesthetics and essences of Chinese characters,making them the most important asset of the Chinese people.Calligraphy and seal engraving,as two closely related systems in traditional Chinese art,have developed through the ages.Due to changes in lifestyle and advancements in modern technology,their original functions of daily writing and verification have gradually diminished.Instead,they have increasingly played a significant role in commercial art.This study utilizes the Evaluation Grid Method(EGM)and the Analytic Hierarchy Process(AHP)to research the key preference factors in the application of calligraphy and seal engraving imagery.Different from the traditional 5-point equal interval semantic questionnaire,this study employs a non-equal interval semantic questionnaire with a golden ratio scale,distinguishing the importance ratio of adjacent semantic meanings and highlighting the weighted emphasis on visual aesthetics.Additionally,the study uses Importance-Performance Analysis(IPA)and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)to obtain the key preference sequence of calligraphy and seal engraving culture.Plus,the Choquet integral comprehensive evaluation is used as a reference for IPA comparison.It is hoped that this study can provide cultural imagery references and research methods,injecting further creativity into industrial design.
文摘Lavinia Fontana’s(1552-1614)Galatea and Cherubs riding the Stormy Waves on a Sea Monster(aka Galatea)of 1590 is an intriguing mythological painting.Being painted on copper,it is a fine example of Lavinia’s exploration of new artistic techniques and materials as well as testimony to her bold artistic interpretations.Lavinia’s Galatea was part of a private collection in Bologna(Diletta Badeschi).This work fascinates the viewer with its erotic audacity and complex iconographical conceits.Recent scholarship by Daniele Benati,Fausto Gozzi,and Enrico Maria Dal Pozzolo assist in unraveling the meaning of this painting.In this essay there are additional interpretative suggestions.
基金the financial support of the project from the National Natural Science Foundation of China(No.61904141)the funding of Natural Science Foundation of Shaanxi Province(No.2020JQ-295)+3 种基金the Key Research and Development Program of Shaanxi(Program No.2020GY-252)National Key Laboratory of Science and Technology on Vacuum Technology and Physics(HTKJ2019KL510007)City University of Hong Kong(Project Nos.7005070 and 9667153)Shenzhen Science and Technology Innovation Committee under the Grant JCYJ20170818103206501。
文摘Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.
基金supported by the National Natural Science Foundation of China(No.51972154)the Natural Science Foundation of Gansu Province(No.20JR5RA244)。
文摘Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.
基金Project supported by Department of Chemical,Petroleum and Gas Engineering,Iran University of Science&Technology(IUST)
文摘Microfluidic solvent extraction （micro SX） of gadolinium was conducted using a mono- and diester mixture （MDEHPA） as the cationic extractant. A microfluidic Y-Y channel was fabricated using CO2- laser technique in a glass microchip used as the extraction system. Compared with batch extraction, extraction kinetic is found fast, and extraction equilibrium is attained within 15 s. Stoichiometry of the extracted complex is found to be Gd（NOs）3-3MDEHPA using log-log plot method. Additionally, the operating parameters and overall volumetric mass transfer coefficient （kLα） were investigated to determine the mass transfer performance. Optimal condition of microextraction for gadolinium using response surface methodology was determined （feed solutions 31 mg/L adjusted to pH value 2.5, extractant concentration 2.9 vol% and extraction time 13.5 s）. In optimal condition, gadolinium extraction yield is obtained 95.5%. Findings of this study approve simplicity, portability, effectiveness, swiftness, and environmental friendliness microfluidic solvent extraction process and reveal that micro SX is useful in the field of extraction strategic metals present at low concentrations, which are otherwise not technically amenable or economically feasible to extract using current traditional methods.
基金Natural Science Foundation of Fujian Province,China (Nos.2019J01740 and 2021J05187)Education and Scientific Research Foundation for Middle-Aged and Young Scientist of Fujian Province,China (Nos.JT180377 and JAT190527)+2 种基金Quanzhou City Science&Technology Program of China (Nos.2018K002 and 2020C039R)Startup Foundation for Doctors of Quanzhou Normal University,China (Nos.H18024 and H18028)Innovation and Entrepreneurship Training Project for College Students,China (Nos.S201910399036 and 202010399113)。
文摘Asymmetrical Y-shaped and Y-ring-shaped frequency selective fabrics(FSFs) were proposed in this paper. They were prepared by computer engraving technology and tested in the anechoic chamber by using the free-space method. The test results of representative samples show that the resonance frequencies and the resonance peak or valley values in two polarization modes are not completely identical but the differentials are small, indicating that the influences of polarization modes are not significant. The transmission coefficient curves of Y-shaped and Y-ring-shaped FSFs with various size parameters are obviously different. For instance, as the unit size D increases by 4.0 mm, the resonance frequencies of patch FSFs decrease by 1.92 GHz and the resonance valleys increase by 12.32 dB. Different size parameters have dissimilar effects on the transmission characteristics and the corresponding influence laws should be analyzed concretely. The work could provide reference for the structural design and characteristics analysis of other FSFs.
文摘This paper researches the main technology of open CNC engraving machine, the DXF identification technology. Agraphic information extraction method is proposed. By this method, the graphic information in DXF file can be identified and transformed into bottom motion controller’s code. So the engraving machine can achieve trajectory tracking. Then the open CNC engraving machine system is developed with C#. At last, the method is validated on a three axes motion experiment platform. The result shows that this method can efficiently identify the graphic information including line, circle, arc etc. in DXF file and the CNC engraving machine can be controlled well.
文摘The art of seal en graving is a comerstone of Chinese fine arts. The seal was originally used as a signature or sign of authority, but it came to be used by all social classes and in much of Asia. The Seal *Engravers Society of Xiling in east China's Zhejiang Province, which was founded a century ago, preserves the art of seal engraving along with approximately 100 other specialized institutions. The design is first sketched on paper, and then engraved on stone, in reverse, with a knife.
文摘This paper uses the method of field research and consulting relevant materials, and then makes an orderly arrangement of the portraits and carvings of the Han Dynasty in China, which contain sports-related content, and further analyzes the Chinese national sports spirit that it shows. The military sports pain depicted in the Han Dynasty's portrait carvings shows the ancient Chinese people's strong and resolute patriotism of looking forward to a peaceful life, pledging to defend their own country, fighting bravely against foreign invaders;Competitive sports show the spirit of indomitable competitive sports and the courage to bear hardships. Sports health care shows the core spirit that people attach importance to health care and cherish life during the Han Dynasty. The sports with myths and legends and ghosts and gods as the main core contents show the Han people's spirit of advocating martial arts, pioneering bravely and fearless of nature and difficulties. However, people engaged in opera, music, dance and figure carving show the sports spirit of the Chinese people in the Han Dynasty, who were full of confidence, positive, bold in innovation and challenging various difficulties.
文摘OVER 2,000 years ago,the bronze craftsmen in today’s Datong City,Shanxi Province,had already mastered the superb skills of copper production.Datong bronze-making craft was included in China’s state-level intangible cultural heritage list in 2014.The craftsmanship which has been passed down through the millennia still shines brightly today after countless hammer blows and engravings.
基金supported by the National Natural Science Foundation of China(No.52374153).
文摘The shear characteristics of the interface formed between a cemented tailings backfill(CTB)and surrounding rocks play a cru-cial role in the design and stability of underground goafs.To investigate the shear behavior of CTB-rock interfaces,rock samples repres-enting the topography of surrounding rocks were constructed using 3D morphology scanning and engraving techniques.A series of direct shear tests were conducted on the CTB rock samples to examine the influence of the cement-tailings ratio on the interfacial shear behavi-or.The results showed that the compressive strength of the CTB and shear strength of the CTB-rock interface decreased with decreasing cement proportion.With deceasing cement content,the failure area of the CTB after the test increased,and the roughness of the newly generated interface reduced.A digital image correlation analysis revealed that the compressive stress concentration in the region with an obtuse angle with respect to the shear direction was the primary cause of CTB failure.Moreover,the correlation between the wear area and the silicon-dense area helped confirm that the silicon particles are more prone to failure in these areas than in other regions.Our find-ings provide new insights into the shear sliding mechanism at CTB-rock interfaces and can aid in the selection of the cement-tailings ra-tio at engineering sites.For example,if the horizontal principal stress of the surrounding rock mass in a backfilling area is relatively high,the cement content can be reduced for CTB applications.
基金National Natural Science Foundation of China,Grant/Award Number:12372093。
文摘The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research topic.To address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving process.In addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving process.By comparing with test data,the simulation accuracy of the coupled dynamics model is verified.Simulation results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not instantaneous.The results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.
基金This work was financially supported by the National Natural Science Foundation of China(NSFC)under Grant No.51175512.
文摘The engraving process of a projectile rotating band is one of the most basic research aspects in interior ballistics,which has not been thoroughly understood thus far.An understanding of this process is of great importance from the viewpoints of optimal design,manufacturing,use,and maintenance of gun and projectile.In this paper,the interaction of copper and nylon rotating bands with a CrNiMo gun barrel during engraving was studied under quasi‐static and dynamic loading conditions.The quasi‐static engraving tests were performed on a CSS‐88500 electronic universal testing machine(EUTM)and a special gas‐gun‐based test rig was designed for dynamic impact engraving of the rotating bands.The mechanical behaviors of copper and nylon were investigated under strain rates of 10^(−3) s^(−1) and 2×10^(3) s^(−1) using an MTS 810 and a split Hopkinson pressure bar(SHPB),respectively.Morphologies of the worn surfaces and cross‐sectional microstructures were observed with scanning electron microscope(SEM)and optical microscope(OM).It was found that large deformation and severe friction occur during engraving.The surface layer is condensed and correlated with a hardness gradient along the depth from the top worn surface.The structure of the rotating band and gun bore,band material,and loading rate have great effects on band engraving.The flow stress‐strain of the copper strongly depends on the applied strain rate.It is suggested that strain rate and temperature play significant roles in the deformation mechanism of rotating bands.
