We demonstrate that,in a simple linearly-polarized plane wave,the optical pulling forces on nanoparticle clusters with gain can be induced by the Fano-like resonance.The numerical results based on the full-wave calcul...We demonstrate that,in a simple linearly-polarized plane wave,the optical pulling forces on nanoparticle clusters with gain can be induced by the Fano-like resonance.The numerical results based on the full-wave calculation show that the optical pulling forces can be attributed to the recoil forces for the nanoparticle clusters composed of dipolar nanoparticles with three different configurations.Interestingly,the recoil forces giving rise to optical pulling forces are exactly dominated by the coupling term between the electric and magnetic dipoles excited in the nanoparticle clusters,while other higherorder terms have a negligible contribution.In addition,the optical pulling force can be tailored by modulating the Fano-like resonance via either the particle size or the gain magnitude,offering an alternative freedom degree for optical manipulations of particle clusters.展开更多
Radial drilling technology,of which the jet bit is the key device,is a research focus in the field of oil drilling and production.This paper establishes mechanical equations for jet bits and analyzes the hydroseal of ...Radial drilling technology,of which the jet bit is the key device,is a research focus in the field of oil drilling and production.This paper establishes mechanical equations for jet bits and analyzes the hydroseal of backward jets in bottom holes.Meanwhile this paper establishes a mechanical equation for a high pressure hose and analyzes the axial force distribution.Laboratory experiments indicate that the flow rate,the angle between the backward nozzle axis and the jet bit axis,and the hole diameter are the major influencing factors;the generation of the pulling force is mainly due to the inlet pressure of the jet bit;the backward jets can significantly increase not only the pulling force but also the stability of jet bits.The pulling force would reach 8,376 N under experimental conditions,which can steadily pull the high-pressure hose forward.展开更多
To solve the difficulty of generating an ideal Bessel beam,an simplified annular transducer model is proposed to study the axial acoustic radiation force(ARF)and the corresponding negative ARF(pulling force)exerted on...To solve the difficulty of generating an ideal Bessel beam,an simplified annular transducer model is proposed to study the axial acoustic radiation force(ARF)and the corresponding negative ARF(pulling force)exerted on centered elastic spheres for acoustic-vortex(AV)beams of arbitrary orders.Based on the theory of acoustic scattering,the axial distributions of the velocity potential and the ARF for AV beams of different orders generated by the annular transducers with different physical sizes are simulated.It is proved that the pulling force can be generated by AV beams of arbitrary orders with multiple axial regions.The pulling force is more likely to exert on the sphere with a smaller k0a(product of the wave number and the radius)for the AV beam with a bigger topological charge due to the strengthened off-axis acoustic scattering.The pulling force decreases with the increase of the axial distance for the sphere with a bigger k0a.More pulling force areas with wider axial regions can be formed by AV beams using a bigger-sized annular transducer.The theoretical results demonstrate the feasibility of generating the pulling force along the axes of AV beams using the experimentally applicable circular array of planar transducers,and suggest application potentials for multi-position stable object manipulations in biomedical engineering.展开更多
We investigate optical force on a graphene-coated gain microparticle by adopting the Maxwell's stress tensor method.It is found that there exists a threshold gain in obtaining the Fano-profile optical force which ...We investigate optical force on a graphene-coated gain microparticle by adopting the Maxwell's stress tensor method.It is found that there exists a threshold gain in obtaining the Fano-profile optical force which indicates the reversal of optical pushing and pulling force. And giant pushing/pulling force can be achieved if the gain value of the material is in the proximity of the threshold gain. Our results show that the threshold gain is more sensitive to the relaxation time than to the Fermi energy of the graphene. We further study the optical force on larger microparticle to demonstrate the pulling force occurring at octupole resonance with small gain value and then it will appear at quadrupole resonance by increasing gain value. Our work provides an in-depth insight into the interaction between light and gain material and gives the additional degree of freedom to optical manipulation of microparticle.展开更多
Hare:Oh,a turnip!A big turnip!I’m hungry.I’ll pull it out.Ai-Hay-Yo,Ai-Hay-Yo.The turnip is too heavy.I can’t pull it out.Dog:I’m a dog.I’m hungry.Oh,Miss Hare,What are you doing?
The Cameroonian flora has a very high biodiversity that remains largely unexplored. It contains many grasses that can be used for sports lawns, but are currently underutilized. In order to contribute to the improvemen...The Cameroonian flora has a very high biodiversity that remains largely unexplored. It contains many grasses that can be used for sports lawns, but are currently underutilized. In order to contribute to the improvement of the quality of sports lawns, nine local grass taxa from the agro-ecological zone with bimodal rainfall in Cameroon were evaluated for their potential for sporting use in natural lawns. The method of the Study and Control Group for Varieties and Seeds was used to evaluate the sports lawn characteristics of the taxa. The resistance to trampling and pulling, the density of the lawn, and the aesthetic appearance, which are factors in calculating the sports index, were monitored at two sites, including the experimental space at the University of Yaounde 1 in the Center region and Kagnol 2 in the East region, from January 2017 to January 2020. The monthly lawn characteristic data allowed for the differentiation between the means and the determination of the sports index of the taxa compared to commercialized lawn varieties. The sports index of the evaluated taxa varied: Cynodon dactylon (6.989), Eleusine indica (6.338), Sporobolus natalensis (6.301), Cynodon cf Cynodon dactylon (6.257), Eragrostis tremula (5.939), Sporobolus pyramidalis (5.583), Agrostis rupestris (5.335), Axonopus compressus (4.991), and Digitaria sp. (4.544). These results show that these grass taxa have potential for sporting use in lawn mixtures at different levels of sports disciplines.展开更多
Currently, open-source software is gradually being integrated into industrial software, while industry protocolsin industrial software are also gradually transferred to open-source community development. Industrial pr...Currently, open-source software is gradually being integrated into industrial software, while industry protocolsin industrial software are also gradually transferred to open-source community development. Industrial protocolstandardization organizations are confronted with fragmented and numerous code PR (Pull Request) and informalproposals, and differentworkflowswill lead to increased operating costs. The open-source community maintenanceteam needs software that is more intelligent to guide the identification and classification of these issues. To solvethe above problems, this paper proposes a PR review prediction model based on multi-dimensional features. Weextract 43 features of PR and divide them into five dimensions: contributor, reviewer, software project, PR, andsocial network of developers. The model integrates the above five-dimensional features, and a prediction model isbuilt based on a Random Forest Classifier to predict the review results of PR. On the other hand, to improve thequality of rejected PRs, we focus on problems raised in the review process and review comments of similar PRs.Wepropose a PR revision recommendation model based on the PR review knowledge graph. Entity information andrelationships between entities are extracted from text and code information of PRs, historical review comments,and related issues. PR revisions will be recommended to code contributors by graph-based similarity calculation.The experimental results illustrate that the above twomodels are effective and robust in PR review result predictionand PR revision recommendation.展开更多
Potassium Lithium Niobate (KLN) crystal belongs to tetragonal system and is ferroelectric crystal,which point group is 4mm and space group is P4bm .The melt point of KLN crystal is about 1050℃.KLN crystal possesses t...Potassium Lithium Niobate (KLN) crystal belongs to tetragonal system and is ferroelectric crystal,which point group is 4mm and space group is P4bm .The melt point of KLN crystal is about 1050℃.KLN crystal possesses tungsten bronze structure and its structure general expression is(A 1) 2(A 2) 4C 4(B 1) 2(B 4) 8O 3.KLN crystal is full fill up tungsten bronze structure crystal,in which the light of transmission band is 0.35-5.0μm.KLN crystal has excellent electro optical and nonlinear property and is superior double frequency crystal material for blue light.KLN crystal also is acoustic surface wave and photorefractive material.KLN crystal cracks easily during it grows.But when KLN crystal is doped in Mn 2O 3 to grow Mn∶KLN crystal,the crystal crack is reduced and the photorefractive property of the crystal is enhanced.KLN system is solid solution system and not congruent composition.The compounding ratio of Mn∶KLN crystal which we grew is 47.4mol% Nb 2O 5,17.3mol% Li 2CO 3,35mol% K 2CO 3 and 0.1mol% Mn 2O 3.The purity of Nb 2O 5,Li 2CO 3,K 2CO 3 and Mn 2O 3 is all 99.99%.Czochralski method was used to grow Mn∶KLN crystal.The technical parameters include the axial direction temperature gradient,the crystal growth rate and the rotation rate.Mn∶KLN crystal with 6mm×8mm×20mm size was grown in the condition that the axial direction temperature gradient is 30℃-40℃,the crystal growth rate is 0.5mm/h and the rotation rate is 10-15r/min.KLN crystal is one dimension ferroelectrics crystal.It has a paraelectrics ferroelectrics phase transition point curie point.So the crystal needs to be polarized in manual work.The direct current field was used to force the self polarization Ps in the same direction and the crystal turn to single domain.Before polarization,the c face needs to be confirmed exactly.The platinum pole was pasted to the two surfaces of c face and the direct current voltage about 220V was added the pole as the polarization outer electrical field.The polarization temperature is 460℃ and the polarization current density is 2mA/cm 2 .The thermal analyzer in TAS100 model was used to analyze the thermal expansion character of Mn∶KLN crystal and ascertain that the curie point of Mn∶KLN crystal is 435℃.It can be seen from the measurement result that the change of thermal expansion rate of Mn∶KLN crystal is smaller than that of pure KLN crystal. So doping Mn 2O 3 in KLN crystal to grow Mn∶KLN crystal can reduce the crack of the crystal.展开更多
ZnO(4mol%),In 2O 3(1mol%)and Fe 2O 3(0.05mol%)were doped in LiNbO 3 and Czochralski method was used to grow Zn∶In∶Fe∶LiNbO 3 crystal.The diameter of the crystal we grew is 30mm.The technology parameter we took is t...ZnO(4mol%),In 2O 3(1mol%)and Fe 2O 3(0.05mol%)were doped in LiNbO 3 and Czochralski method was used to grow Zn∶In∶Fe∶LiNbO 3 crystal.The diameter of the crystal we grew is 30mm.The technology parameter we took is that the axial temperature gradient is 40℃/cm,the growth rate is 1mm/h, the rotation rate is 15-25r/min,the temperature of polarization is 1220℃ and the current density of polarization is 5mA/cm 2.The wafer dimension is 10mm×10mm×3mm and was covered in Li 2CO 3 powder to reduce.The reduction temperature is 500℃ and reduction time is 30 hours. OH - stretch vibration transmission spectra were measured by Fourier infrared spectrophotometer. There are two absorption peaks in OH - spectra of Zn∶In∶Fe∶LiNbO 3,in which one is at 3534cm -1 (2.83μm) and the other is at 3505cm -1 (2.85μm).The peak at 2.85μm is far lower than that at 2.83μm. Because of the threshold effect of Zn 2+ and In 3+ ,the peak at 2.83μm is generated and the peak at 2.85μm is related with Fe 3+ .In LiNbO 3 only doped with Fe,Li + site is taken place by Fe 3+ .When doping Zn 2+ and In 3+ in high concentration,these two ions take place Nb that is at Li site and Fe 3+ substitutes for Nb 5+ at the same time.The interaction between Fe 3+ and OH - make the OH - peak shift to 2.85μm.展开更多
基金Project supported by the Natural Science Foundation of Guangxi Province of China (Grant No.2021GXNSFDA196001)the National Natural Science Foundation of China (Grant Nos.12174076,12074084,and 12204117)+1 种基金Guangxi Science and Technology Project (Grant Nos.AD22080042 and AB21220052)Open Project of State Key Laboratory of Surface Physics in Fudan University (Grant No.KF2022_15)。
文摘We demonstrate that,in a simple linearly-polarized plane wave,the optical pulling forces on nanoparticle clusters with gain can be induced by the Fano-like resonance.The numerical results based on the full-wave calculation show that the optical pulling forces can be attributed to the recoil forces for the nanoparticle clusters composed of dipolar nanoparticles with three different configurations.Interestingly,the recoil forces giving rise to optical pulling forces are exactly dominated by the coupling term between the electric and magnetic dipoles excited in the nanoparticle clusters,while other higherorder terms have a negligible contribution.In addition,the optical pulling force can be tailored by modulating the Fano-like resonance via either the particle size or the gain magnitude,offering an alternative freedom degree for optical manipulations of particle clusters.
基金supported by High-tech Research and Development Program of China (No. 2007AA09Z315)Doctoral Foundation of Ministry of Education of China (No. 20070425006)
文摘Radial drilling technology,of which the jet bit is the key device,is a research focus in the field of oil drilling and production.This paper establishes mechanical equations for jet bits and analyzes the hydroseal of backward jets in bottom holes.Meanwhile this paper establishes a mechanical equation for a high pressure hose and analyzes the axial force distribution.Laboratory experiments indicate that the flow rate,the angle between the backward nozzle axis and the jet bit axis,and the hole diameter are the major influencing factors;the generation of the pulling force is mainly due to the inlet pressure of the jet bit;the backward jets can significantly increase not only the pulling force but also the stability of jet bits.The pulling force would reach 8,376 N under experimental conditions,which can steadily pull the high-pressure hose forward.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11934009,11974187,and 11604156).
文摘To solve the difficulty of generating an ideal Bessel beam,an simplified annular transducer model is proposed to study the axial acoustic radiation force(ARF)and the corresponding negative ARF(pulling force)exerted on centered elastic spheres for acoustic-vortex(AV)beams of arbitrary orders.Based on the theory of acoustic scattering,the axial distributions of the velocity potential and the ARF for AV beams of different orders generated by the annular transducers with different physical sizes are simulated.It is proved that the pulling force can be generated by AV beams of arbitrary orders with multiple axial regions.The pulling force is more likely to exert on the sphere with a smaller k0a(product of the wave number and the radius)for the AV beam with a bigger topological charge due to the strengthened off-axis acoustic scattering.The pulling force decreases with the increase of the axial distance for the sphere with a bigger k0a.More pulling force areas with wider axial regions can be formed by AV beams using a bigger-sized annular transducer.The theoretical results demonstrate the feasibility of generating the pulling force along the axes of AV beams using the experimentally applicable circular array of planar transducers,and suggest application potentials for multi-position stable object manipulations in biomedical engineering.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11904184, 11847033, and 11704158)the Natural Science Foundation of Jiangsu Province,China (Grant No. BK20170170)。
文摘We investigate optical force on a graphene-coated gain microparticle by adopting the Maxwell's stress tensor method.It is found that there exists a threshold gain in obtaining the Fano-profile optical force which indicates the reversal of optical pushing and pulling force. And giant pushing/pulling force can be achieved if the gain value of the material is in the proximity of the threshold gain. Our results show that the threshold gain is more sensitive to the relaxation time than to the Fermi energy of the graphene. We further study the optical force on larger microparticle to demonstrate the pulling force occurring at octupole resonance with small gain value and then it will appear at quadrupole resonance by increasing gain value. Our work provides an in-depth insight into the interaction between light and gain material and gives the additional degree of freedom to optical manipulation of microparticle.
文摘Hare:Oh,a turnip!A big turnip!I’m hungry.I’ll pull it out.Ai-Hay-Yo,Ai-Hay-Yo.The turnip is too heavy.I can’t pull it out.Dog:I’m a dog.I’m hungry.Oh,Miss Hare,What are you doing?
文摘The Cameroonian flora has a very high biodiversity that remains largely unexplored. It contains many grasses that can be used for sports lawns, but are currently underutilized. In order to contribute to the improvement of the quality of sports lawns, nine local grass taxa from the agro-ecological zone with bimodal rainfall in Cameroon were evaluated for their potential for sporting use in natural lawns. The method of the Study and Control Group for Varieties and Seeds was used to evaluate the sports lawn characteristics of the taxa. The resistance to trampling and pulling, the density of the lawn, and the aesthetic appearance, which are factors in calculating the sports index, were monitored at two sites, including the experimental space at the University of Yaounde 1 in the Center region and Kagnol 2 in the East region, from January 2017 to January 2020. The monthly lawn characteristic data allowed for the differentiation between the means and the determination of the sports index of the taxa compared to commercialized lawn varieties. The sports index of the evaluated taxa varied: Cynodon dactylon (6.989), Eleusine indica (6.338), Sporobolus natalensis (6.301), Cynodon cf Cynodon dactylon (6.257), Eragrostis tremula (5.939), Sporobolus pyramidalis (5.583), Agrostis rupestris (5.335), Axonopus compressus (4.991), and Digitaria sp. (4.544). These results show that these grass taxa have potential for sporting use in lawn mixtures at different levels of sports disciplines.
基金support of National Social Science Fund(NSSF)under Grant(No.22BTQ033).
文摘Currently, open-source software is gradually being integrated into industrial software, while industry protocolsin industrial software are also gradually transferred to open-source community development. Industrial protocolstandardization organizations are confronted with fragmented and numerous code PR (Pull Request) and informalproposals, and differentworkflowswill lead to increased operating costs. The open-source community maintenanceteam needs software that is more intelligent to guide the identification and classification of these issues. To solvethe above problems, this paper proposes a PR review prediction model based on multi-dimensional features. Weextract 43 features of PR and divide them into five dimensions: contributor, reviewer, software project, PR, andsocial network of developers. The model integrates the above five-dimensional features, and a prediction model isbuilt based on a Random Forest Classifier to predict the review results of PR. On the other hand, to improve thequality of rejected PRs, we focus on problems raised in the review process and review comments of similar PRs.Wepropose a PR revision recommendation model based on the PR review knowledge graph. Entity information andrelationships between entities are extracted from text and code information of PRs, historical review comments,and related issues. PR revisions will be recommended to code contributors by graph-based similarity calculation.The experimental results illustrate that the above twomodels are effective and robust in PR review result predictionand PR revision recommendation.
文摘Potassium Lithium Niobate (KLN) crystal belongs to tetragonal system and is ferroelectric crystal,which point group is 4mm and space group is P4bm .The melt point of KLN crystal is about 1050℃.KLN crystal possesses tungsten bronze structure and its structure general expression is(A 1) 2(A 2) 4C 4(B 1) 2(B 4) 8O 3.KLN crystal is full fill up tungsten bronze structure crystal,in which the light of transmission band is 0.35-5.0μm.KLN crystal has excellent electro optical and nonlinear property and is superior double frequency crystal material for blue light.KLN crystal also is acoustic surface wave and photorefractive material.KLN crystal cracks easily during it grows.But when KLN crystal is doped in Mn 2O 3 to grow Mn∶KLN crystal,the crystal crack is reduced and the photorefractive property of the crystal is enhanced.KLN system is solid solution system and not congruent composition.The compounding ratio of Mn∶KLN crystal which we grew is 47.4mol% Nb 2O 5,17.3mol% Li 2CO 3,35mol% K 2CO 3 and 0.1mol% Mn 2O 3.The purity of Nb 2O 5,Li 2CO 3,K 2CO 3 and Mn 2O 3 is all 99.99%.Czochralski method was used to grow Mn∶KLN crystal.The technical parameters include the axial direction temperature gradient,the crystal growth rate and the rotation rate.Mn∶KLN crystal with 6mm×8mm×20mm size was grown in the condition that the axial direction temperature gradient is 30℃-40℃,the crystal growth rate is 0.5mm/h and the rotation rate is 10-15r/min.KLN crystal is one dimension ferroelectrics crystal.It has a paraelectrics ferroelectrics phase transition point curie point.So the crystal needs to be polarized in manual work.The direct current field was used to force the self polarization Ps in the same direction and the crystal turn to single domain.Before polarization,the c face needs to be confirmed exactly.The platinum pole was pasted to the two surfaces of c face and the direct current voltage about 220V was added the pole as the polarization outer electrical field.The polarization temperature is 460℃ and the polarization current density is 2mA/cm 2 .The thermal analyzer in TAS100 model was used to analyze the thermal expansion character of Mn∶KLN crystal and ascertain that the curie point of Mn∶KLN crystal is 435℃.It can be seen from the measurement result that the change of thermal expansion rate of Mn∶KLN crystal is smaller than that of pure KLN crystal. So doping Mn 2O 3 in KLN crystal to grow Mn∶KLN crystal can reduce the crack of the crystal.
文摘ZnO(4mol%),In 2O 3(1mol%)and Fe 2O 3(0.05mol%)were doped in LiNbO 3 and Czochralski method was used to grow Zn∶In∶Fe∶LiNbO 3 crystal.The diameter of the crystal we grew is 30mm.The technology parameter we took is that the axial temperature gradient is 40℃/cm,the growth rate is 1mm/h, the rotation rate is 15-25r/min,the temperature of polarization is 1220℃ and the current density of polarization is 5mA/cm 2.The wafer dimension is 10mm×10mm×3mm and was covered in Li 2CO 3 powder to reduce.The reduction temperature is 500℃ and reduction time is 30 hours. OH - stretch vibration transmission spectra were measured by Fourier infrared spectrophotometer. There are two absorption peaks in OH - spectra of Zn∶In∶Fe∶LiNbO 3,in which one is at 3534cm -1 (2.83μm) and the other is at 3505cm -1 (2.85μm).The peak at 2.85μm is far lower than that at 2.83μm. Because of the threshold effect of Zn 2+ and In 3+ ,the peak at 2.83μm is generated and the peak at 2.85μm is related with Fe 3+ .In LiNbO 3 only doped with Fe,Li + site is taken place by Fe 3+ .When doping Zn 2+ and In 3+ in high concentration,these two ions take place Nb that is at Li site and Fe 3+ substitutes for Nb 5+ at the same time.The interaction between Fe 3+ and OH - make the OH - peak shift to 2.85μm.
