Lightening structure is one of the goals of many fields of research. As a result, magnesium alloys are studied due to their low density. However, one drawback of these alloys is their low formability at room temperatu...Lightening structure is one of the goals of many fields of research. As a result, magnesium alloys are studied due to their low density. However, one drawback of these alloys is their low formability at room temperature due to their hexagonal closed-packed structure. In the present work, the forming capacity of an AZ31 Mg alloys has been studied using a mini deep-drawing device, image correlation techniques and tests (tension and expansion) at temperatures contained between 20°C and 200°C. To investigate formability limits of Mg alloys in expansion, major and minor strains data were generated using hemispherical punch tests and analyzed with 3D digital images correlation techniques. Thanks to images correlation, strains on the surface of the samples were observed by means of a double digitization of the sample in three dimensions before and after deformation by using stereoscopic vision and triangulation. Image correlations have also been used in 2D to measure strains on the surface of the tensile test samples. These tests gave interesting information on the evolution of various parameters such as hardening coefficient, strain rate sensitivity parameter, and Lankford coefficient, which may affect the behavior of the alloys. Finally, the forming limits in both configurations (tension and expansion) were compared and discussed.展开更多
Piezoelectric material-based semi-active vibration control systems may effectively suppress vibration amplitude without any external power supply,or even harvest electrical energy.This bidirectional electrical energy ...Piezoelectric material-based semi-active vibration control systems may effectively suppress vibration amplitude without any external power supply,or even harvest electrical energy.This bidirectional electrical energy control phenomenon is theoretically introduced and validated in this paper.A flyback transformer-based switching piezoelectric shunt circuit that can extract energy from or inject energy into piezoelectric elements is proposed.The analytical expressions of the controlled energy and the corresponding vibration attenuation are therefore derived for a classical electromechanical cantilever beam.Theoretical predictions validated by the experimental results show that the structure vibration attenuation can be tuned from−5 to−25 dB under the given electrical quality factor of the circuit and figure of merit of the electromechanical structure,and the consumed power is in the range of−13 to 25 mW,which is a good theoretical basis for the development of self-sensing,self-adapting,and self-powered piezoelectric vibration control systems.展开更多
Understanding the electrical transport in carbon nanotube(CNT)materials is one key to reach very high electrical conductivities.All CNT material resistivity(ρ(T))as function of the temperature are fully apprehended b...Understanding the electrical transport in carbon nanotube(CNT)materials is one key to reach very high electrical conductivities.All CNT material resistivity(ρ(T))as function of the temperature are fully apprehended by their reduced activation W(T)=dln(ρ)/dln(T)curves.Up to now,no model accurately fits W(T)curves,thus preventing from precisely describing the CNT material electrical transport.We present a new electrical transport model that perfectly fits all W(T)curves found in the literature and in our own data.CNT material resistivities are modeled byρ(T)=ρ0(T^−α+M(1+βTγT^2)).Our model has few enough parameters(α,M,β,γ)to relate them to the CNT physics.Below 70 K,we experimentally show that CNT material resistivity follows the Luttinger Liquid theory justifying the T^−αterm in our model.Above 70 K,the polynomial part becomes dominant and depends on the two different CNT fabrication techniques which lead to two very different yarn structures.For yarns made from floating catalyst chemical vapor deposition CNTs,the polynomial is explained by the percolation of metallic CNT walls.Whereas,the polynomial of yarns spun from CNT arrays is explained by the electrical transport in CNT bundles which are the basic building blocks of this type of yarns.展开更多
In the pursuit for scalable quantum processors,significanteffort has been devoted to the development of cryogenic classical hardware for the control and readout of a growingnumber of qubits.The current work presented ...In the pursuit for scalable quantum processors,significanteffort has been devoted to the development of cryogenic classical hardware for the control and readout of a growingnumber of qubits.The current work presented a novelapproach called impedancemetry that is suitable for measuringthe quantum capacitance of semiconductor qubits connected toa resonant LC-circuit.The impedancemetry circuit exploits theintegration of a complementary metal-oxide-semiconductor(CMOS)active inductor in the resonator with tunable resonance frequency and quality factor,enabling the optimizationof readout sensitivity for quantum devices.The realized cryogenic circuit allows fast impedance detection with a measuredcapacitance resolution down to 10 aF and an input-referrednoise of 3.7 aF/Hz p.At 4.2 K,the power consumption of theactive inductor amounts to 120μW,with an additional dissipation for on-chip current excitation(0.15μW)and voltageamplification(2.9 mW)of the impedance measurement.Compared to the commonly used schemes based on dispersiveRF reflectometry which require millimeter-scale passive inductors,the circuit exhibits a notably reduced footprint(50μm360μm),facilitating its integration in a scalable quantumclassical architecture.The impedancemetry method has been applied at 4.2 K to the detection of quantum effects in the gatecapacitance of on-chip nanometric CMOS transistors that areindividually addressed via multiplexing.展开更多
Recently,an increasing number of parts have been produced using additive manufacturing technology.They are no longer simply prototypes but structural parts whose mechanical characteristics must be known before printin...Recently,an increasing number of parts have been produced using additive manufacturing technology.They are no longer simply prototypes but structural parts whose mechanical characteristics must be known before printing.One of the weaknesses of 3D printing is the significant variability in the dimensions and geometrical and mechanical properties of the printed parts.These properties depend on specific printing parameters and environmental conditions.This study aims to determine the influence of two printing parameters,namely,the orientation and positioning of the parts on the printing platform and the influence of humidity on the mechanical properties of the parts.The studied samples were fabricated with onyx using a Markforged X7 printer.The results showed that onyx could be considered an isotropic material to a certain extent because its mechanical properties do not vary sufficiently according to the orientation angle on the printing platform;a maximum deviation of 10%was observed between the different orientations.In contrast to the orientation,the positioning(flat or XY,on-edge or XZ,and upright or ZX)of the workpieces significantly influenced the mechanical properties.Positioning on the edge allowed the Young’s modulus to be up to 50% greater than that of flat and upright positioning.The study of the sensitivity to humidity revealed that a specimen absorbs approximately 2%of the humidity and loses up to 65%of its Young’s modulus after 165 days of exposure,significantly influencing the mechanical properties of the parts.Consideration should be given to this aging of onyx when using printed parts as structural parts.展开更多
This article investigates the interest of using in-situ piezoelectric(PZT and PVDF)disks to perform real-time Structural Health Monitoring(SHM)of glass fiber-reinforced polymer composites submitted to var-ious tensile...This article investigates the interest of using in-situ piezoelectric(PZT and PVDF)disks to perform real-time Structural Health Monitoring(SHM)of glass fiber-reinforced polymer composites submitted to var-ious tensile loadings.The goal is to evaluate the working range and SHM potential of such embedded transducers for relatively simple mechanical loadings,with the long-term aim of using them to monitor complete 3D structures submitted to more complex loadings.SHM is performed acquiring the electrical capacitance variation of the embedded transducers.To study the potential links between the insitu capacitance signal and the global response of the loaded host specimens,a multi-instrumentation composed of external Nondestructive Testing techniques was implemented on the surfaces of the specimens to search for multi-physical couplings between these external measurements and the capacitance curves.Results confirmed the non-intrusiveness of the embedded transducers,and allowed estimating their working domain.PZT capacitance signal follows well the mechanical loadings,but the piezoceramic transducer gets damaged after a determined relatively low strain level due to its brittleness.The limits of this working domain are extended by using a stretchable PolyVinylidene Fluoride(PVDF)polymer transducer,allowing this one to perform in-situ and real-time SHM of its host tensile specimens until failure.展开更多
In this work, we introduce a polymer version of a previously developed silicon MEMS drop deposition tool for surfacefunctionalization that consists of a microcantilever integrating an open fluidic channel and a reserv...In this work, we introduce a polymer version of a previously developed silicon MEMS drop deposition tool for surfacefunctionalization that consists of a microcantilever integrating an open fluidic channel and a reservoir. The device isfabricated by laser stereolithography, which offers the advantages of low-cost and fast prototyping. Additionally,thanks to the ability to process multiple materials, a magnetic base is incorporated into the cantilever for convenienthandling and attachment to the holder of a robotized stage used for spotting. Droplets with diameters ranging from∼50 μm to ∼300 μm are printed upon direct contact of the cantilever tip with the surface to pattern. Liquid loading isachieved by fully immersing the cantilever into a reservoir drop, where a single load results in the deposition of morethan 200 droplets. The influences of the size and shape of the cantilever tip and the reservoir on the printing outcomeare studied. As a proof-of-concept of the biofunctionalization capability of this 3D printed droplet dispenser,microarrays of oligonucleotides and antibodies displaying high specificity and no cross-contamination are fabricated,and droplets are deposited at the tip of an optical fiber bundle.展开更多
To enhance the reproducibility and scale up the synthesis of colloidal quantum dots(QDs),continuous flow synthesis is an appealing alternative to the widely used batch synthesis.Amongst other advantages,the strongly e...To enhance the reproducibility and scale up the synthesis of colloidal quantum dots(QDs),continuous flow synthesis is an appealing alternative to the widely used batch synthesis.Amongst other advantages,the strongly enhanced heat and mass transfer in small tubular reactors combined with controlled pressure can be cited.Nonetheless,the widespread use of this technique is hampered by special requirements such as the absence of solid or gaseous products and the room-temperature solubility of precursors.Therefore,the transfer of established reaction conditions from batch to flow is not straightforward and in most reported works the optical properties of the obtained QDs lag behind those prepared in batch reactions.This is also the case for PbS-based QDs,which are established near infrared(NIR)absorbers/emitters.Here we identified experimental conditions giving access to high-quality PbS core and PbS/CdS core/shell QDs obtained in an automated,easily scalable continuous flow synthesis.In particular,substituted thioureas have been selected as the sulfur source and ex-situ synthesized lead and cadmium oleate as the metal precursors,and appropriate solvent mixtures have been identified for each precursor.Highly luminescent PbS/CdS QDs emitting at the target wavelengths 940 and 1130 nm of special interest for NIR light-emitting diodes have been prepared,exhibiting a photoluminescence quantum yield up to 91%.展开更多
文摘Lightening structure is one of the goals of many fields of research. As a result, magnesium alloys are studied due to their low density. However, one drawback of these alloys is their low formability at room temperature due to their hexagonal closed-packed structure. In the present work, the forming capacity of an AZ31 Mg alloys has been studied using a mini deep-drawing device, image correlation techniques and tests (tension and expansion) at temperatures contained between 20°C and 200°C. To investigate formability limits of Mg alloys in expansion, major and minor strains data were generated using hemispherical punch tests and analyzed with 3D digital images correlation techniques. Thanks to images correlation, strains on the surface of the samples were observed by means of a double digitization of the sample in three dimensions before and after deformation by using stereoscopic vision and triangulation. Image correlations have also been used in 2D to measure strains on the surface of the tensile test samples. These tests gave interesting information on the evolution of various parameters such as hardening coefficient, strain rate sensitivity parameter, and Lankford coefficient, which may affect the behavior of the alloys. Finally, the forming limits in both configurations (tension and expansion) were compared and discussed.
基金National Key Research and Development Program of China,Grant/Award Number:2021 YFB3400100National Natural Science Foundation of China,Grant/Award Numbers:52241103,U2241261Fund of Prospective Layout of Scientific Research for Nanjing University of Aeronautics and Astronautics。
文摘Piezoelectric material-based semi-active vibration control systems may effectively suppress vibration amplitude without any external power supply,or even harvest electrical energy.This bidirectional electrical energy control phenomenon is theoretically introduced and validated in this paper.A flyback transformer-based switching piezoelectric shunt circuit that can extract energy from or inject energy into piezoelectric elements is proposed.The analytical expressions of the controlled energy and the corresponding vibration attenuation are therefore derived for a classical electromechanical cantilever beam.Theoretical predictions validated by the experimental results show that the structure vibration attenuation can be tuned from−5 to−25 dB under the given electrical quality factor of the circuit and figure of merit of the electromechanical structure,and the consumed power is in the range of−13 to 25 mW,which is a good theoretical basis for the development of self-sensing,self-adapting,and self-powered piezoelectric vibration control systems.
文摘Understanding the electrical transport in carbon nanotube(CNT)materials is one key to reach very high electrical conductivities.All CNT material resistivity(ρ(T))as function of the temperature are fully apprehended by their reduced activation W(T)=dln(ρ)/dln(T)curves.Up to now,no model accurately fits W(T)curves,thus preventing from precisely describing the CNT material electrical transport.We present a new electrical transport model that perfectly fits all W(T)curves found in the literature and in our own data.CNT material resistivities are modeled byρ(T)=ρ0(T^−α+M(1+βTγT^2)).Our model has few enough parameters(α,M,β,γ)to relate them to the CNT physics.Below 70 K,we experimentally show that CNT material resistivity follows the Luttinger Liquid theory justifying the T^−αterm in our model.Above 70 K,the polynomial part becomes dominant and depends on the two different CNT fabrication techniques which lead to two very different yarn structures.For yarns made from floating catalyst chemical vapor deposition CNTs,the polynomial is explained by the percolation of metallic CNT walls.Whereas,the polynomial of yarns spun from CNT arrays is explained by the electrical transport in CNT bundles which are the basic building blocks of this type of yarns.
基金supported by the EuropeanUnion’s Horizon 2020 Research and Innovation program under GrantAgreement No.810504(ERC Synergy project QuCube).
文摘In the pursuit for scalable quantum processors,significanteffort has been devoted to the development of cryogenic classical hardware for the control and readout of a growingnumber of qubits.The current work presented a novelapproach called impedancemetry that is suitable for measuringthe quantum capacitance of semiconductor qubits connected toa resonant LC-circuit.The impedancemetry circuit exploits theintegration of a complementary metal-oxide-semiconductor(CMOS)active inductor in the resonator with tunable resonance frequency and quality factor,enabling the optimizationof readout sensitivity for quantum devices.The realized cryogenic circuit allows fast impedance detection with a measuredcapacitance resolution down to 10 aF and an input-referrednoise of 3.7 aF/Hz p.At 4.2 K,the power consumption of theactive inductor amounts to 120μW,with an additional dissipation for on-chip current excitation(0.15μW)and voltageamplification(2.9 mW)of the impedance measurement.Compared to the commonly used schemes based on dispersiveRF reflectometry which require millimeter-scale passive inductors,the circuit exhibits a notably reduced footprint(50μm360μm),facilitating its integration in a scalable quantumclassical architecture.The impedancemetry method has been applied at 4.2 K to the detection of quantum effects in the gatecapacitance of on-chip nanometric CMOS transistors that areindividually addressed via multiplexing.
文摘Recently,an increasing number of parts have been produced using additive manufacturing technology.They are no longer simply prototypes but structural parts whose mechanical characteristics must be known before printing.One of the weaknesses of 3D printing is the significant variability in the dimensions and geometrical and mechanical properties of the printed parts.These properties depend on specific printing parameters and environmental conditions.This study aims to determine the influence of two printing parameters,namely,the orientation and positioning of the parts on the printing platform and the influence of humidity on the mechanical properties of the parts.The studied samples were fabricated with onyx using a Markforged X7 printer.The results showed that onyx could be considered an isotropic material to a certain extent because its mechanical properties do not vary sufficiently according to the orientation angle on the printing platform;a maximum deviation of 10%was observed between the different orientations.In contrast to the orientation,the positioning(flat or XY,on-edge or XZ,and upright or ZX)of the workpieces significantly influenced the mechanical properties.Positioning on the edge allowed the Young’s modulus to be up to 50% greater than that of flat and upright positioning.The study of the sensitivity to humidity revealed that a specimen absorbs approximately 2%of the humidity and loses up to 65%of its Young’s modulus after 165 days of exposure,significantly influencing the mechanical properties of the parts.Consideration should be given to this aging of onyx when using printed parts as structural parts.
文摘This article investigates the interest of using in-situ piezoelectric(PZT and PVDF)disks to perform real-time Structural Health Monitoring(SHM)of glass fiber-reinforced polymer composites submitted to var-ious tensile loadings.The goal is to evaluate the working range and SHM potential of such embedded transducers for relatively simple mechanical loadings,with the long-term aim of using them to monitor complete 3D structures submitted to more complex loadings.SHM is performed acquiring the electrical capacitance variation of the embedded transducers.To study the potential links between the insitu capacitance signal and the global response of the loaded host specimens,a multi-instrumentation composed of external Nondestructive Testing techniques was implemented on the surfaces of the specimens to search for multi-physical couplings between these external measurements and the capacitance curves.Results confirmed the non-intrusiveness of the embedded transducers,and allowed estimating their working domain.PZT capacitance signal follows well the mechanical loadings,but the piezoceramic transducer gets damaged after a determined relatively low strain level due to its brittleness.The limits of this working domain are extended by using a stretchable PolyVinylidene Fluoride(PVDF)polymer transducer,allowing this one to perform in-situ and real-time SHM of its host tensile specimens until failure.
基金This work was supported by the French National Research Agency(ANR)under the research project MOLY(grant ANR-15-CE19–0005)and CBH-EUR-GS(ANR-17-EURE-0003)by the European Union’s Horizon 2020 research and innovation program as part of the HoliFAB project(grant agreement no.760927)+1 种基金by FEDER European Regional Funds and French Région Occitanie as part of the MultiFAB project(grant agreement number 16007407/MP00115MP0011594)by the Labex ARCANE,and by the French national technological network RENATECH.
文摘In this work, we introduce a polymer version of a previously developed silicon MEMS drop deposition tool for surfacefunctionalization that consists of a microcantilever integrating an open fluidic channel and a reservoir. The device isfabricated by laser stereolithography, which offers the advantages of low-cost and fast prototyping. Additionally,thanks to the ability to process multiple materials, a magnetic base is incorporated into the cantilever for convenienthandling and attachment to the holder of a robotized stage used for spotting. Droplets with diameters ranging from∼50 μm to ∼300 μm are printed upon direct contact of the cantilever tip with the surface to pattern. Liquid loading isachieved by fully immersing the cantilever into a reservoir drop, where a single load results in the deposition of morethan 200 droplets. The influences of the size and shape of the cantilever tip and the reservoir on the printing outcomeare studied. As a proof-of-concept of the biofunctionalization capability of this 3D printed droplet dispenser,microarrays of oligonucleotides and antibodies displaying high specificity and no cross-contamination are fabricated,and droplets are deposited at the tip of an optical fiber bundle.
基金platforms of the Grenoble Instruct-ERIC center(ISBGUAR 3518 CNRSCEA-UGA-EMBL)within the Grenoble Partnership for Structural Biology(PSB)+1 种基金supported by FRISBI(ANR-10-INBS-0005-02)financed within the University Grenoble Alpes graduate school(Ecoles Universitaires de Recherche)CBH-EUR-GS(ANR-17-EURE-0003).
文摘To enhance the reproducibility and scale up the synthesis of colloidal quantum dots(QDs),continuous flow synthesis is an appealing alternative to the widely used batch synthesis.Amongst other advantages,the strongly enhanced heat and mass transfer in small tubular reactors combined with controlled pressure can be cited.Nonetheless,the widespread use of this technique is hampered by special requirements such as the absence of solid or gaseous products and the room-temperature solubility of precursors.Therefore,the transfer of established reaction conditions from batch to flow is not straightforward and in most reported works the optical properties of the obtained QDs lag behind those prepared in batch reactions.This is also the case for PbS-based QDs,which are established near infrared(NIR)absorbers/emitters.Here we identified experimental conditions giving access to high-quality PbS core and PbS/CdS core/shell QDs obtained in an automated,easily scalable continuous flow synthesis.In particular,substituted thioureas have been selected as the sulfur source and ex-situ synthesized lead and cadmium oleate as the metal precursors,and appropriate solvent mixtures have been identified for each precursor.Highly luminescent PbS/CdS QDs emitting at the target wavelengths 940 and 1130 nm of special interest for NIR light-emitting diodes have been prepared,exhibiting a photoluminescence quantum yield up to 91%.
