On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, t...On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, the growth rate of prismatic faces is slower and more sensitive to the additives and impurities for ADP crystals. When the supersaturation is low, the advance of growth steps on prismatic face can be blocked by ethanol or impurities, the crystal morphology is changed from the tetragonal prism to shuttle (i.e., the tapered shape). The tapering formation of ADP crystallites was structurally studied in a novel view.展开更多
We propose and experimentally demonstrate a broadband 1 × 3 adiabatic splitter based on the silicon-on-insulator technology, with simultaneous tapering of velocity and coupling. The designed structure becomes sim...We propose and experimentally demonstrate a broadband 1 × 3 adiabatic splitter based on the silicon-on-insulator technology, with simultaneous tapering of velocity and coupling. The designed structure becomes simulated transmission uniformity of three outputs better than 0.5dB in a broadband of 250nm, and a large simulated fabrication tolerance is obtained. A manufactured splitter whose parameters greatly diverge from the design acquires a measured result of the worst splitting ratio better than 1.5dB as well as an excess loss lower than 0.8 dB in a large wavelength range of 80nm. A post-simulation based on the tested splitter obtains a result that meets the actual transmission well.展开更多
The performance of the optical fiber coupler prepared with fused biconical taper method is determined by the quality of fused stretching. Besides, the stable high-temperature heat source is the essential guarantee for...The performance of the optical fiber coupler prepared with fused biconical taper method is determined by the quality of fused stretching. Besides, the stable high-temperature heat source is the essential guarantee for fused stretching process to go smoothly. The way of using AC （alternating current） arc as the heat source is proposed in this article. In addition, the paper also introduces high-frequency high-voltage power supply with the characteristics of constant current and restricted voltage, which is composed of preceding voltage regulation part and following inverter.展开更多
Rheumatoid arthritis(RA),as a chronic autoimmune disease,significantly impairs patients'quality of life.(1)Glucocorticoids(GC)remain crucial in RA management even in the biologics era,owing to their potent anti-in...Rheumatoid arthritis(RA),as a chronic autoimmune disease,significantly impairs patients'quality of life.(1)Glucocorticoids(GC)remain crucial in RA management even in the biologics era,owing to their potent anti-inflammatory and immunosuppressive properties.However,prolonged GC use carries significant safety risks,including infections,osteoporosis,and cardiovascular complications.Therefore,clinical guidelines advocate minimizing both the dose and duration of GC therapy.展开更多
We have demonstrated the highly efficient excitation of the linearly polarized mode(LP01)in ring-core fibers(RCFs)by tapering the spliced point between the RCF and the standard single-mode fiber(SMF)to optimize all-fi...We have demonstrated the highly efficient excitation of the linearly polarized mode(LP01)in ring-core fibers(RCFs)by tapering the spliced point between the RCF and the standard single-mode fiber(SMF)to optimize all-fiber orbital angular momentum(OAM)generation.The tapering technique has been investigated theoretically and experimentally.Before tapering,only 50%of light can be coupled from SMFs to RCFs.The modal interference spectrum with an extinction ratio(ER)of～9 dB is observed,showing that higher-order modes are excited in RCF.By tapering the spliced point,90%of light is coupled,and the ER is minimized to be～2 dB,indicating that the higher-order modes are effectively suppressed by tapering.Such tapered spliced points of RCF–SMF are further applied for all-fiber OAM generation.The efficiencies of OAM+1 and OAM?1 generation are found to be enhanced by approximately 11.66%and 12.41%,respectively,showing that the tapered spliced point of the RCF–SMF is a feasible way to optimize OAM generation.展开更多
Optical fibres with diameters at micro-or sub-micrometre scale are widely adopted as a convenient tool for studying light–matter interactions.To prepare such devices,two elements are indispensable:a heat source and a...Optical fibres with diameters at micro-or sub-micrometre scale are widely adopted as a convenient tool for studying light–matter interactions.To prepare such devices,two elements are indispensable:a heat source and a pulling force.In this paper,we report a novel fibre-tapering technique in which micro-sized plasmonic heaters and elaborately deformed optical fibres are compactly combined,free of flame and bulky pulling elements.Using this technique,micro-nano fibres with abrupt taper and ultra-short transition regions were successfully fabricated,which would otherwise be a challenge for traditional techniques.The compactness of the proposed system enabled it to be further transferred to a scanning electron microscope for in-situ monitoring of the tapering process.The essential dynamics of“heat and pull”was directly visualised with nanometre precision in real time and theoretically interpreted,thereby establishing an example for future in-situ observations of micro and nanoscale light-matter interactions.展开更多
A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-single- mode （SMS） fiber structure heated by hydrogen flame. The interference fringe begins to form when tapering lengt...A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-single- mode （SMS） fiber structure heated by hydrogen flame. The interference fringe begins to form when tapering length is 19.8 mm, and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller. Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5 μm. The temperature and axial strain dependences of the tapered SMS structure are characterized, and the measured temperature and strain coefficients are ＋7 pm/℃ and -9.536 pm/με, respectively.展开更多
Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF ...Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.展开更多
In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to con...In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to concentrate free silver nanoparticles(AgNPs)within an optofluidic chip,significantly enhancing SERS performance.We investigated the optical field distribution characteristics within the tapered fiber using COMSOL simulation software and established a MATLAB simulation model to validate the single-beam optical trap's effectiveness in capturing AgNPs,demonstrating the theoretical feasibility of our approach.To verify the particle capture efficacy of the system,we experimentally controlled the optical trap's on-off state to manage the capture and release of particles precisely.The experimental results indicated that the Raman signal intensity in the capture state was significantly higher than in the non-capture state,confirming that the single-beam optical trap effectively enhances the SERS detection capability of the optofluidic detection system.Furthermore,we employed Raman mapping techniques to investigate the impact of the capture area on the SERS effect,revealing that the spectral intensity of molecular fingerprints in the laser-trapping region is significantly improved.We successfully detected the Raman spectrum of crystal violet at a concentration of 10^(−9)mol/L and pesticide thiram at a concentration of 10^(−5)mol/L,further demonstrating the ability of the single-beam optical trap in enhancing the molecular fingerprint spectrum identification capability of the SERS optofluidic chips.The optical trapping SERS optofluidic detection system developed in this study,as a key component of an integrated optoelectronic sensing system,holds the potential for integration with portable high-power lasers and high-performance Raman spectrometers.This integration is expected to advance highly integrated technologies and significantly enhance the overall performance and portability of optoelectronic sensing systems.展开更多
Stem volume estimation is crucial in forest ecology and management,particularly for timber harvesting strategies and carbon stock assessments.This study aimed to develop a variable-exponent taper equation specifically...Stem volume estimation is crucial in forest ecology and management,particularly for timber harvesting strategies and carbon stock assessments.This study aimed to develop a variable-exponent taper equation specifically tailored to savanna tree species using close-range photogrammetry(CRP)data and to evaluate its performance against conventional volume equations for stem volume estimation.A dataset of 30 trees across five dominant savanna species was used to fit the taper model,which was validated using a separate dataset of 322 trees from 14 species.The results demonstrated significant improvements in volume estimation accuracy when using the taper equation.At the tree level,the root mean square error(RMSE)decreased by 47%,from 598 to 319 dm^(3),and the mean absolute bias(MAB)by 48%,from 328 to 172 dm3,compared to volume equations.Similarly,at the plot level,RMSE was reduced by 42% and MAB by 40%.The model performed well for species with regular forms.However,species with irregular tapers exhibited higher errors,reflecting the challenges of modeling stem forms of mixed species.The use of CRP proved valuable,providing high-resolution diameter measurements that improved model parameterization.This study underscores the importance of advanced data collection methods for enhancing taper model accuracy and suggests that further species-specific adjustments are needed to improve performance for species with irregular forms.The findings support the broader application of taper equations for improving stem volume estimates in savanna ecosystems,contributing to better forest management and resource monitoring practices.展开更多
Fabrication of optical fiber tapers is realized with a combination of plasmonic microheaters and specially designed structural bending of optical fibers,which provide the necessary elements of"heat and pull"...Fabrication of optical fiber tapers is realized with a combination of plasmonic microheaters and specially designed structural bending of optical fibers,which provide the necessary elements of"heat and pull".The resultant compactness and flame-free condition enable monitoring of the tapering process inside a scanning electron microscope.展开更多
In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to c...In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without corrugations.The results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube sandwich.Furthermore,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency.Additionally,the tapered corrugated tubes'resistance to oblique impacts was studied.Compared to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical simulations.After conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall thickness.EA and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.展开更多
Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its development.In order to obtain higher aerodynamic efficien...Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its development.In order to obtain higher aerodynamic efficiency at an altitude of 22 km,a certain near-space composite propeller is designed as a long and slender aerodynamic shape with a 10 m diameter,which brings many challenges to the composite structure design.The initial design is obtained by the composite structure variable stiffness design method using based on fixed region division blending model.However,it weighs 23.142 kg,exceeding the required 20 kg.In order to meet the structural design requirements of the propeller,a variable stiffness design method using the adaptive region division blending model is proposed in this paper.Compared with the methods using the fixed region division blending model,this method optimizes region division,stacking thickness and stacking sequence in a single level,considering the coupling effect among them.Through a more refined region division,this method can provide a more optimal design for composite tapered structures.Additionally,to improve the efficiency of optimization subjected to manufacturing constraints,a hierarchical penalty function is proposed to quickly filter out the solutions that do not meet manufacturing constraints.The above methods combined with a Genetic Algorithm(GA)using specific encoding are adopted to optimize the near-space composite propeller.The optimal design of the structure weighs 18.831 kg,with all manufacturing constraints and all structural response constraints being satisfied.Compared with the initial design,the optimal design has a more refined region division,and achieves a weight reduction of 18.6%.This demonstrates that a refined region division can significantly improve the mechanical performance of the composite tapered structure.展开更多
This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into f...This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into finite segments in the vertical direction and the Voigt model is applied to simulate the vertical support of the surrounding soil acting on the pile segment.The surrounding soil is divided into finite ring-shaped zones in the radial direction to consider the construction disturbance.Then,the shear complex stiffness at the pile-soil interface is derived by solving the dynamic equilibrium equation for the soil from the outermost to innermost zone.The displacement impedance at the top of an arbitrary pile segment is obtained by solving the dynamic equilibrium equation for the pile and is combined with the vertical support of the surrounding soil to derive the displacement impedance at the bottom of the upper adjacent segment.Further,the displacement impedance at the pile head is obtained based on the impedance function transfer technique.Finally,the reliability of the proposed solution is verified,followed by a sensitivity analysis concerning the coupling effect of the pile parameters,construction disturbance and the vertical support of the surrounding soil on the displacement impedance of the pile.展开更多
The application of mathematical modeling to biological fluids is of utmost importance, as it has diverse applicationsin medicine. The peristaltic mechanism plays a crucial role in understanding numerous biological flo...The application of mathematical modeling to biological fluids is of utmost importance, as it has diverse applicationsin medicine. The peristaltic mechanism plays a crucial role in understanding numerous biological flows. In thispaper, we present a theoretical investigation of the double diffusion convection in the peristaltic transport of aPrandtl nanofluid through an asymmetric tapered channel under the combined action of thermal radiation andan induced magnetic field. The equations for the current flow scenario are developed, incorporating relevantassumptions, and considering the effect of viscous dissipation. The impact of thermal radiation and doublediffusion on public health is of particular interest. For instance, infrared radiation techniques have been used totreat various skin-related diseases and can also be employed as a measure of thermotherapy for some bones toenhance blood circulation, with radiation increasing blood flow by approximately 80%. To solve the governingequations, we employ a numerical method with the aid of symbolic software such as Mathematica and MATLAB.The velocity, magnetic force function, pressure rise, temperature, solute (species) concentration, and nanoparticlevolume fraction profiles are analytically derived and graphically displayed. The results outcomes are compared withthe findings of limiting situations for verification.展开更多
The travel time and amplitude of ground-penetrating radar （GPR） waves are closely related to medium parameters such as water content, porosity, and dielectric permittivity. However, conventional estimation methods, ...The travel time and amplitude of ground-penetrating radar （GPR） waves are closely related to medium parameters such as water content, porosity, and dielectric permittivity. However, conventional estimation methods, which are mostly based on wave velocity, are not suitable for real complex media because of limited resolution. Impedance inversion uses the reflection coefficient of radar waves to directly calculate GPR impedance and other parameters of subsurface media. We construct a 3D multiscale stochastic medium model and use the mixed Gaussian and exponential autocorrelation function to describe the distribution of parameters in real subsurface media. We introduce an elliptical Gaussian function to describe local random anomalies. The tapering function is also introduced to reduce calculation errors caused by the numerical simulation of discrete grids. We derive the impedance inversion workflow and test the calculation precision in complex media. Finally, we use impedance inversion to process GPR field data in a polluted site in Mongolia. The inversion results were constrained using borehole data and validated by resistivity data.展开更多
The configuration and the reference frame of the four-axis wire-electric discharge machining （WEDM） machine tool are introduced. Based on the motion analysis of the four-axis WEDM machine tool, an algorithm for cont...The configuration and the reference frame of the four-axis wire-electric discharge machining （WEDM） machine tool are introduced. Based on the motion analysis of the four-axis WEDM machine tool, an algorithm for controlling the four-axis motion is proposed. The algorithm is applicable to both the invariable and variable taper machining. Motion loci of the machining platform and the wire guiding head are deduced by the algorithm according to the bottom surface locus of the workpiece and the taper angle. The algorithm is used in the CNC system of the four-axis WEDM machine tool and confirmed to be effective.展开更多
In order to detect the refractive index of liquid with high precision,based on modular interference,Mach-Zehnder optical fiber refractive rate sensor was studied.Sensor structure is composed of ordinary single-mode fi...In order to detect the refractive index of liquid with high precision,based on modular interference,Mach-Zehnder optical fiber refractive rate sensor was studied.Sensor structure is composed of ordinary single-mode fiber and multimode fiber,according to the singlemode multimode singlemode sequence to fuse together,and the fused optical fiber is used to process the taper.As a result,the diameter of the sensing head is about 10μm.Experimental results show that,as liquid refractive index increases range from 1.33 to 1.35,the loss peak of the transmission spectrum will shift to long wave direction.展开更多
基金Project supported by the National Natural Science Foundation of China (20471012), the Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), the Research Fund for the Doctoral Program of Higher Education (20040141004) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, the growth rate of prismatic faces is slower and more sensitive to the additives and impurities for ADP crystals. When the supersaturation is low, the advance of growth steps on prismatic face can be blocked by ethanol or impurities, the crystal morphology is changed from the tetragonal prism to shuttle (i.e., the tapered shape). The tapering formation of ADP crystallites was structurally studied in a novel view.
基金Supported by the National High-Technology Research and Development Program of China under Grant Nos 2015AA016904and 2013AA014402the National Basic Research Program of China under Grant No 2011CB301701the National Natural Science Foundation of China under Grant No 61275065
文摘We propose and experimentally demonstrate a broadband 1 × 3 adiabatic splitter based on the silicon-on-insulator technology, with simultaneous tapering of velocity and coupling. The designed structure becomes simulated transmission uniformity of three outputs better than 0.5dB in a broadband of 250nm, and a large simulated fabrication tolerance is obtained. A manufactured splitter whose parameters greatly diverge from the design acquires a measured result of the worst splitting ratio better than 1.5dB as well as an excess loss lower than 0.8 dB in a large wavelength range of 80nm. A post-simulation based on the tested splitter obtains a result that meets the actual transmission well.
文摘The performance of the optical fiber coupler prepared with fused biconical taper method is determined by the quality of fused stretching. Besides, the stable high-temperature heat source is the essential guarantee for fused stretching process to go smoothly. The way of using AC （alternating current） arc as the heat source is proposed in this article. In addition, the paper also introduces high-frequency high-voltage power supply with the characteristics of constant current and restricted voltage, which is composed of preceding voltage regulation part and following inverter.
文摘Rheumatoid arthritis(RA),as a chronic autoimmune disease,significantly impairs patients'quality of life.(1)Glucocorticoids(GC)remain crucial in RA management even in the biologics era,owing to their potent anti-inflammatory and immunosuppressive properties.However,prolonged GC use carries significant safety risks,including infections,osteoporosis,and cardiovascular complications.Therefore,clinical guidelines advocate minimizing both the dose and duration of GC therapy.
基金supported by the National Natural Science Foundation of China(Nos.61635006,61975108,and 61605108)the Shuguang Program(No.16SG35).
文摘We have demonstrated the highly efficient excitation of the linearly polarized mode(LP01)in ring-core fibers(RCFs)by tapering the spliced point between the RCF and the standard single-mode fiber(SMF)to optimize all-fiber orbital angular momentum(OAM)generation.The tapering technique has been investigated theoretically and experimentally.Before tapering,only 50%of light can be coupled from SMFs to RCFs.The modal interference spectrum with an extinction ratio(ER)of～9 dB is observed,showing that higher-order modes are excited in RCF.By tapering the spliced point,90%of light is coupled,and the ER is minimized to be～2 dB,indicating that the higher-order modes are effectively suppressed by tapering.Such tapered spliced points of RCF–SMF are further applied for all-fiber OAM generation.The efficiencies of OAM+1 and OAM?1 generation are found to be enhanced by approximately 11.66%and 12.41%,respectively,showing that the tapered spliced point of the RCF–SMF is a feasible way to optimize OAM generation.
基金supported by the National Natural Science Foundation of China(Grant Nos.61927820,61905201,and 62275221).
文摘Optical fibres with diameters at micro-or sub-micrometre scale are widely adopted as a convenient tool for studying light–matter interactions.To prepare such devices,two elements are indispensable:a heat source and a pulling force.In this paper,we report a novel fibre-tapering technique in which micro-sized plasmonic heaters and elaborately deformed optical fibres are compactly combined,free of flame and bulky pulling elements.Using this technique,micro-nano fibres with abrupt taper and ultra-short transition regions were successfully fabricated,which would otherwise be a challenge for traditional techniques.The compactness of the proposed system enabled it to be further transferred to a scanning electron microscope for in-situ monitoring of the tapering process.The essential dynamics of“heat and pull”was directly visualised with nanometre precision in real time and theoretically interpreted,thereby establishing an example for future in-situ observations of micro and nanoscale light-matter interactions.
基金supported in part by the National "973" Program of China(No.2011CB301700)the National Natural Science Foundation of China(Nos.61007052, 61071011,61107041,61127016)+3 种基金the International Cooperation Project from the Ministry of Science and Technology of China(No.2011FDA11780)the STCSM Project(Nos.09JC1408100,10DJ1400402)the "SMC Young Star" Scientist Program of Shanghai Jiao Tong Universitythe National Key Lab Projects(No. GKZD030021)
文摘A modal interferometer is experimentally demonstrated based on tapering a single-mode-multimode-single- mode （SMS） fiber structure heated by hydrogen flame. The interference fringe begins to form when tapering length is 19.8 mm, and becomes regular and clear when the tapering length is longer and the tapered waist diameter is smaller. Annealing process is undertaken to achieve a high extension ratio of approximately 17 dB with free spectral range of 1.5 nm when the tapering length is 33 mm and the tapered waist diameter is approximately 5 μm. The temperature and axial strain dependences of the tapered SMS structure are characterized, and the measured temperature and strain coefficients are ＋7 pm/℃ and -9.536 pm/με, respectively.
基金the National Science and Technology Major Project of China(No.2019-VII0017e0158)the National Natural Science Foundation of China(No.U21A20131)+1 种基金the Industry-University Research Cooperation Project,China(No.HFZL2020CXY025)the National Key Laboratory of Science and Technology on Helicopter Transmission,China(No.HTL-O-21G05).
文摘Spiral bevel gears are critical transmission components,and are widely used in the aerospace field.This paper proposes a new multi-DOF envelope forming process for fabricating spiral bevel gears.Firstly,the multi-DOF envelope forming principle of spiral bevel gears is proposed.Secondly,the design methods for the envelope tool geometry and movement are proposed based on the envelope geometry and movement relationships.Thirdly,the metal flow and tooth filling laws are revealed through 3D FE simulation of the multi-DOF envelope forming process of a typical spiral bevel gear.Fourthly,a new method for separating the envelope tool and the formed spiral bevel gear with back taper tooth is proposed to avoid their interference.Finally,experiments on multi-DOF envelope forming of this typical spiral bevel gear are conducted using new heavy load multi-DOF envelope forming equipment.The simulation and experimental results show the feasibility of the proposed multi-DOF envelope forming process for fabricating spiral bevel gears with back taper tooth and the corresponding process design methods.
基金financial supports from National Natural Science Foundation of China(62175023).
文摘In this study,we developed a single-beam optical trap-based surface-enhanced Raman scattering(SERS)optofluidic molecular fingerprint spectroscopy detection system.This system utilizes a single-beam optical trap to concentrate free silver nanoparticles(AgNPs)within an optofluidic chip,significantly enhancing SERS performance.We investigated the optical field distribution characteristics within the tapered fiber using COMSOL simulation software and established a MATLAB simulation model to validate the single-beam optical trap's effectiveness in capturing AgNPs,demonstrating the theoretical feasibility of our approach.To verify the particle capture efficacy of the system,we experimentally controlled the optical trap's on-off state to manage the capture and release of particles precisely.The experimental results indicated that the Raman signal intensity in the capture state was significantly higher than in the non-capture state,confirming that the single-beam optical trap effectively enhances the SERS detection capability of the optofluidic detection system.Furthermore,we employed Raman mapping techniques to investigate the impact of the capture area on the SERS effect,revealing that the spectral intensity of molecular fingerprints in the laser-trapping region is significantly improved.We successfully detected the Raman spectrum of crystal violet at a concentration of 10^(−9)mol/L and pesticide thiram at a concentration of 10^(−5)mol/L,further demonstrating the ability of the single-beam optical trap in enhancing the molecular fingerprint spectrum identification capability of the SERS optofluidic chips.The optical trapping SERS optofluidic detection system developed in this study,as a key component of an integrated optoelectronic sensing system,holds the potential for integration with portable high-power lasers and high-performance Raman spectrometers.This integration is expected to advance highly integrated technologies and significantly enhance the overall performance and portability of optoelectronic sensing systems.
基金partially funded by the International Foundation for Science(Grant No:I-1-D-6066-1).
文摘Stem volume estimation is crucial in forest ecology and management,particularly for timber harvesting strategies and carbon stock assessments.This study aimed to develop a variable-exponent taper equation specifically tailored to savanna tree species using close-range photogrammetry(CRP)data and to evaluate its performance against conventional volume equations for stem volume estimation.A dataset of 30 trees across five dominant savanna species was used to fit the taper model,which was validated using a separate dataset of 322 trees from 14 species.The results demonstrated significant improvements in volume estimation accuracy when using the taper equation.At the tree level,the root mean square error(RMSE)decreased by 47%,from 598 to 319 dm^(3),and the mean absolute bias(MAB)by 48%,from 328 to 172 dm3,compared to volume equations.Similarly,at the plot level,RMSE was reduced by 42% and MAB by 40%.The model performed well for species with regular forms.However,species with irregular tapers exhibited higher errors,reflecting the challenges of modeling stem forms of mixed species.The use of CRP proved valuable,providing high-resolution diameter measurements that improved model parameterization.This study underscores the importance of advanced data collection methods for enhancing taper model accuracy and suggests that further species-specific adjustments are needed to improve performance for species with irregular forms.The findings support the broader application of taper equations for improving stem volume estimates in savanna ecosystems,contributing to better forest management and resource monitoring practices.
文摘Fabrication of optical fiber tapers is realized with a combination of plasmonic microheaters and specially designed structural bending of optical fibers,which provide the necessary elements of"heat and pull".The resultant compactness and flame-free condition enable monitoring of the tapering process inside a scanning electron microscope.
基金the grants from the National Natural Science Foundation of China(Nos.52078152 and 12002095)Guangzhou Government-University Union Fund(No.202201020532)。
文摘In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without corrugations.The results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube sandwich.Furthermore,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency.Additionally,the tapered corrugated tubes'resistance to oblique impacts was studied.Compared to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical simulations.After conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall thickness.EA and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.
基金This study was co-supported by stable funding from the National Key Laboratory of Aerofoil and Grille Aerodynamics,China.
文摘Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its development.In order to obtain higher aerodynamic efficiency at an altitude of 22 km,a certain near-space composite propeller is designed as a long and slender aerodynamic shape with a 10 m diameter,which brings many challenges to the composite structure design.The initial design is obtained by the composite structure variable stiffness design method using based on fixed region division blending model.However,it weighs 23.142 kg,exceeding the required 20 kg.In order to meet the structural design requirements of the propeller,a variable stiffness design method using the adaptive region division blending model is proposed in this paper.Compared with the methods using the fixed region division blending model,this method optimizes region division,stacking thickness and stacking sequence in a single level,considering the coupling effect among them.Through a more refined region division,this method can provide a more optimal design for composite tapered structures.Additionally,to improve the efficiency of optimization subjected to manufacturing constraints,a hierarchical penalty function is proposed to quickly filter out the solutions that do not meet manufacturing constraints.The above methods combined with a Genetic Algorithm(GA)using specific encoding are adopted to optimize the near-space composite propeller.The optimal design of the structure weighs 18.831 kg,with all manufacturing constraints and all structural response constraints being satisfied.Compared with the initial design,the optimal design has a more refined region division,and achieves a weight reduction of 18.6%.This demonstrates that a refined region division can significantly improve the mechanical performance of the composite tapered structure.
基金National Natural Science Foundation of China under Grand No.51808190the Central Government Guides Local Science and Technology Development Fund Projects under Grand No.XZ202301YD0019C+2 种基金the Foundation of Key Laboratory of Soft Soils and Geoenvironmental Engineering(Zhejiang University)Ministry of Education under Grand No.2022P04the Central University Basic Research Fund of China under Grand No.B220202017。
文摘This research is concentrated on the longitudinal vibration of a tapered pipe pile considering the vertical support of the surrounding soil and construction disturbance.First,the pile-soil system is partitioned into finite segments in the vertical direction and the Voigt model is applied to simulate the vertical support of the surrounding soil acting on the pile segment.The surrounding soil is divided into finite ring-shaped zones in the radial direction to consider the construction disturbance.Then,the shear complex stiffness at the pile-soil interface is derived by solving the dynamic equilibrium equation for the soil from the outermost to innermost zone.The displacement impedance at the top of an arbitrary pile segment is obtained by solving the dynamic equilibrium equation for the pile and is combined with the vertical support of the surrounding soil to derive the displacement impedance at the bottom of the upper adjacent segment.Further,the displacement impedance at the pile head is obtained based on the impedance function transfer technique.Finally,the reliability of the proposed solution is verified,followed by a sensitivity analysis concerning the coupling effect of the pile parameters,construction disturbance and the vertical support of the surrounding soil on the displacement impedance of the pile.
基金Institutional Fund Projects under No.(IFP-A-2022-2-5-24)by Ministry of Education and University of Hafr Al Batin,Saudi Arabia.
文摘The application of mathematical modeling to biological fluids is of utmost importance, as it has diverse applicationsin medicine. The peristaltic mechanism plays a crucial role in understanding numerous biological flows. In thispaper, we present a theoretical investigation of the double diffusion convection in the peristaltic transport of aPrandtl nanofluid through an asymmetric tapered channel under the combined action of thermal radiation andan induced magnetic field. The equations for the current flow scenario are developed, incorporating relevantassumptions, and considering the effect of viscous dissipation. The impact of thermal radiation and doublediffusion on public health is of particular interest. For instance, infrared radiation techniques have been used totreat various skin-related diseases and can also be employed as a measure of thermotherapy for some bones toenhance blood circulation, with radiation increasing blood flow by approximately 80%. To solve the governingequations, we employ a numerical method with the aid of symbolic software such as Mathematica and MATLAB.The velocity, magnetic force function, pressure rise, temperature, solute (species) concentration, and nanoparticlevolume fraction profiles are analytically derived and graphically displayed. The results outcomes are compared withthe findings of limiting situations for verification.
基金supported by the Doctoral Fund Project of the Ministry of Education(No.20130061110060 class tutors)the Post-Doctoral Fund Project(No.2015M571366)+1 种基金the National Natural Science Foundation of China(No.41174097)US DoD ARO Project"Advanced Mathematical Algorithm"(No.W911NF-11-2-0046)
文摘The travel time and amplitude of ground-penetrating radar （GPR） waves are closely related to medium parameters such as water content, porosity, and dielectric permittivity. However, conventional estimation methods, which are mostly based on wave velocity, are not suitable for real complex media because of limited resolution. Impedance inversion uses the reflection coefficient of radar waves to directly calculate GPR impedance and other parameters of subsurface media. We construct a 3D multiscale stochastic medium model and use the mixed Gaussian and exponential autocorrelation function to describe the distribution of parameters in real subsurface media. We introduce an elliptical Gaussian function to describe local random anomalies. The tapering function is also introduced to reduce calculation errors caused by the numerical simulation of discrete grids. We derive the impedance inversion workflow and test the calculation precision in complex media. Finally, we use impedance inversion to process GPR field data in a polluted site in Mongolia. The inversion results were constrained using borehole data and validated by resistivity data.
文摘The configuration and the reference frame of the four-axis wire-electric discharge machining （WEDM） machine tool are introduced. Based on the motion analysis of the four-axis WEDM machine tool, an algorithm for controlling the four-axis motion is proposed. The algorithm is applicable to both the invariable and variable taper machining. Motion loci of the machining platform and the wire guiding head are deduced by the algorithm according to the bottom surface locus of the workpiece and the taper angle. The algorithm is used in the CNC system of the four-axis WEDM machine tool and confirmed to be effective.
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 Shanxi ProvinceProgram for Top Young Academic Leaders of Higher Learning Institutions in Shanxi Province
文摘In order to detect the refractive index of liquid with high precision,based on modular interference,Mach-Zehnder optical fiber refractive rate sensor was studied.Sensor structure is composed of ordinary single-mode fiber and multimode fiber,according to the singlemode multimode singlemode sequence to fuse together,and the fused optical fiber is used to process the taper.As a result,the diameter of the sensing head is about 10μm.Experimental results show that,as liquid refractive index increases range from 1.33 to 1.35,the loss peak of the transmission spectrum will shift to long wave direction.
