In this paper,the joint design of transmit and receive beamformers for transmit subaperturing multiple-input-multiple-output(TS-MIMO)radar is investigated,aiming to enhance its low probability of intercept(LPI)capabil...In this paper,the joint design of transmit and receive beamformers for transmit subaperturing multiple-input-multiple-output(TS-MIMO)radar is investigated,aiming to enhance its low probability of intercept(LPI)capability.The main objective is to simultaneously minimize the transmission power,suppress the transmit sidelobe levels,and minimize the probability of intercept,thus bolstering the LPI performance of the radar system while maintaining the desired target detection performance.An alternative optimization method is proposed to jointly optimize the transmit and receive beamformers,yielding an unified LPI optimization framework.Particularly,the proposed iterative algorithm based on the Lagrange duality theory for transmit beamforming is more efficient than the conventional convex optimization method.Numerical experiments highlight the effectiveness of the proposed approach in sidelobe suppression and computational efficiency.展开更多
In recent years,the use of deep learning to replace traditional numerical methods for electromagnetic propagation has shown tremendous potential in the rapid design of photonic devices.However,most research on deep le...In recent years,the use of deep learning to replace traditional numerical methods for electromagnetic propagation has shown tremendous potential in the rapid design of photonic devices.However,most research on deep learning has focused on single-layer grating couplers,and the accuracy of multi-layer grating couplers has not yet reached a high level.This paper proposes and demonstrates a novel deep learning network-assisted strategy for inverse design.The network model is based on a multi-layer perceptron(MLP)and incorporates convolutional neural networks(CNNs)and transformers.Through the stacking of multiple layers,it achieves a high-precision design for both multi-layer and single-layer raster couplers with various functionalities.The deep learning network exhibits exceptionally high predictive accuracy,with an average absolute error across the full wavelength range of 1300–1700 nm being only 0.17%,and an even lower predictive absolute error below 0.09%at the specific wavelength of 1550 nm.By combining the deep learning network with the genetic algorithm,we can efficiently design grating couplers that perform different functions.Simulation results indicate that the designed single-wavelength grating couplers achieve coupling efficiencies exceeding 80%at central wavelengths of 1550 nm and 1310 nm.The performance of designed dual-wavelength and broadband grating couplers also reaches high industry standards.Furthermore,the network structure and inverse design method are highly scalable and can be applied not only to multi-layer grating couplers but also directly to the prediction and design of single-layer grating couplers,providing a new perspective for the innovative development of photonic devices.展开更多
The generation of high-quality 3D models from single 2D images remains challenging in terms of accuracy and completeness.Deep learning has emerged as a promising solution,offering new avenues for improvements.However,...The generation of high-quality 3D models from single 2D images remains challenging in terms of accuracy and completeness.Deep learning has emerged as a promising solution,offering new avenues for improvements.However,building models from scratch is computationally expensive and requires large datasets.This paper presents a transfer-learning-based approach for category-specific 3D reconstruction from a single 2D image.The core idea is to fine-tune a pre-trained model on specific object categories using new,unseen data,resulting in specialized versions of the model that are better adapted to reconstruct particular objects.The proposed approach utilizes a three-phase pipeline comprising image acquisition,3D reconstruction,and refinement.After ensuring the quality of the input image,a ResNet50 model is used for object recognition,directing the image to the corresponding category-specific model to generate a voxel-based representation.The voxel-based 3D model is then refined by transforming it into a detailed triangular mesh representation using the Marching Cubes algorithm and Laplacian smoothing.An experimental study,using the Pix2Vox model and the Pascal3D dataset,has been conducted to evaluate and validate the effectiveness of the proposed approach.Results demonstrate that category-specific fine-tuning of Pix2Vox significantly outperforms both the original model and the general model fine-tuned for all object categories,with substantial gains in Intersection over Union(IoU)scores.Visual assessments confirm improvements in geometric detail and surface realism.These findings indicate that combining transfer learning with category-specific fine tuning and refinement strategy of our approach leads to better-quality 3D model generation.展开更多
We studied the decomposition of two haloacetic acids(HAAs),dichloroacetic acid(DCAA)and trichloroacetic acid(TCAA),in water by single oxidants ozone(O3)and ultraviolet radiation(UV)and the advanced oxidation processes...We studied the decomposition of two haloacetic acids(HAAs),dichloroacetic acid(DCAA)and trichloroacetic acid(TCAA),in water by single oxidants ozone(O3)and ultraviolet radiation(UV)and the advanced oxidation processes(AOPs)constituted by the combinations of O3/UV,H2O2/UV,O3/H2O2,and O3/H2O2/UV.The concentrations of HAAs were analyzed at specified time intervals to track their decomposition.Except for O3 and UV,the four combined oxidation processes remarkably enhance the decomposition of DCAA and TCAA owing to the generated very reactive hydroxyl radicals.The fastest decomposition process is O3/H2O2/UV,closely followed by O3/UV.DCAA is much easier to decompose than TCAA.The kinetics of HAA decomposition by O3/UV can be described well by a pseudo first-order reaction model under a constant initial dissolved O3 concentration and fixed UV radiation.Humic acids and HCO3-in the reaction system both decrease the decomposition rate constants for DCAA and TCAA.The amount of H2O2 accumulates in the presence of humic acids in the O3/UV process.展开更多
We demonstrate a silicon nitride photonics-based imaging system that can perform one-dimensional interferometric imaging around the 1550-nm wavelength.The magnetograph using interferometric and computational imaging f...We demonstrate a silicon nitride photonics-based imaging system that can perform one-dimensional interferometric imaging around the 1550-nm wavelength.The magnetograph using interferometric and computational imaging for remote observations(MICRO)design uses silicon nitride on a Si platform to replace the bulky free-space optics of traditional magnetograph imaging systems with nanofabricated structures of a fraction of the size.The photonic integrated circuit(PIC)uses an array of lenslets that couple light into four input waveguides with spacing arranged along a Golomb ruler,where each aperture pair formed has a unique length.Each aperture is mixed with a 13-dBm reference laser and separated inside a 2×4 optical hybrid to generate in-phase and quadrature-phase signals to be detected in balanced detectors at the output of the PIC.We use a field programmable gate array(FPGA)board to digitize and process the measurements.The FPGAs and PIC are combined to reduce the overall size,weight,and power of the system,paving the way for a compact imaging system.We demonstrate a PIC-based imager design and experimental testbed for spectrometry applications.展开更多
Jumping robots are highly capable of overcoming obstacles.However,their explosive force,short duration,and variable trajectories pose significant challenges in achieving stable landings in complex environments.Traditi...Jumping robots are highly capable of overcoming obstacles.However,their explosive force,short duration,and variable trajectories pose significant challenges in achieving stable landings in complex environments.Traditional approaches rely heavily on sophisticated algorithms and electronic sensor feedback systems to ensure landing stability,which increases the implementation complexity.Inspired by the process by which humans complete jumps and achieve stable landings in complex environments,this study proposes a novel landing control method for jumping robots.By designing a mechanically coupled perception-control structure based on mechanical logic computing,the robot simulates the real-time transmission of neural signals triggered by the ground reaction force(GRF)in human reflex loops,thereby simplifying traditional control approaches.Through the collaboration of a flexible mechanical spine and a bistable foot module,the robot achieves an average height of 16.8 cm and a distance of 25.36 cm in consecutive stable jumps.It also demonstrates reliable landing performance on challenging terrain including slopes and cobblestone surfaces.This paper proposes a novel landing control method for jumping robots that simplifies traditional control approaches.The method enables stable landings on complex terrain through a mechanically coupled perception-control structure.This approach has potential applications in tasks requiring mobility over uneven terrain,such as search and rescue.展开更多
The output regulation approach has effectively addressed the speed tracking and disturbance rejection problem of permanent magnet synchronous motor(PMSM).Although accurate speed tracking under time-varying load torque...The output regulation approach has effectively addressed the speed tracking and disturbance rejection problem of permanent magnet synchronous motor(PMSM).Although accurate speed tracking under time-varying load torque disturbance has been achieved,the number of disturbance frequencies should be known.In this paper,an adaptive observer-based error feedback control method is proposed,which can solve the speed tracking control problem of PMSM subject to completely unknown multi-frequency sinusoidal load torque disturbance,requiring only the upper bound of the number of disturbance frequencies.The design steps of this method can be divided into the following three steps.In step one,a filtered transformation is applied to convert the observer canonical form of the error system and the transformed exosystem into an adaptive observer form.In step two,an adaptive observer is designed to estimate the unknown parameters of the exosystem and states of the adaptive observer form.In step three,an adaptive observer-based error feedback controller is designed to solve this control problem.The effectiveness of the proposed method is demonstrated by experimental results.展开更多
The anodic electrochemical ozone production(EOP)and the cathodic three-electron oxygen reduction reaction(3e^(-)ORR)are effective processes for generating active oxygen species(ROS).However,the activation of ozone(O_(...The anodic electrochemical ozone production(EOP)and the cathodic three-electron oxygen reduction reaction(3e^(-)ORR)are effective processes for generating active oxygen species(ROS).However,the activation of ozone(O_(3))by hydroxyl radical(OH)to form ROS poses significant challenges.The micelle balllike bimetallic La-Nb oxides(LNOx)have been developed as a bifunctional electrocatalyst for both the EOP and 3e^(-)ORR reactions.The LNO20 demonstrated a 9.8%of Faradaic efficiency(FE)in O_(3)production and a transfer number of 2.8 electrons in the 3e^(-)ORR.Theoretical calculations support the notion that the five-membered ring mechanism in LNO20 facilitates O_(3)production.Additionally,the incorporation of La provides active sites that enhance the activation of hydrogen peroxide(^(*)H_(2)O_(2))and the generation of OH.This innovative approach synergistically integrates EOP and 3e^(-)ORR,enhancing the activation of O_(3)to produce ROS,demonstrating exceptional efficacy in the degradation of organic pollutants and antimicrobial activity.The study paves the way for designing advanced electrocatalysts for EOP and 3e^(-)ORR and offers insights into utilizing electrochemical method to support other antibacterial strategies.展开更多
Interfacial defects and environmental instability at perovskite surfaces pose significant challenges for inverted perovskite solar cells(PSCs). Surface post-treatment strategies have emerged as a viable approach to im...Interfacial defects and environmental instability at perovskite surfaces pose significant challenges for inverted perovskite solar cells(PSCs). Surface post-treatment strategies have emerged as a viable approach to improve film quality and passivate defects. Although organic molecules can passivate both surfaces and grain boundaries via hydrogen or covalent bonding,their limited adsorption specificity often results in incomplete defect neutralization. In this work, we introduce a bilayer passivation approach employing phenethylammonium iodide(PEAI) and n-octylammonium iodide(OAI) to concurrently mitigate nonradiative recombination and improve stability. PEAI passivates undercoordinated Pb^(2+) at grain boundaries and surfaces, effectively eliminating deep-level traps and suppressing non-radiative losses. Meanwhile, OAI forms a hydrophobic barrier on the perovskite surface through its long alkyl chains, inhibiting moisture penetration without compromising interfacial charge transport. As a result, the perovskite film exhibits significantly enhanced optoelectronic performance and environmental stability,achieving a champion power conversion efficiency(PCE) of 24.48%.展开更多
The Chilean subduction zone is one of the most seismically active regions globally,characterized by extensive intermediatedepth seismicity in the slab.In this study,we construct a new earthquake catalog for northern C...The Chilean subduction zone is one of the most seismically active regions globally,characterized by extensive intermediatedepth seismicity in the slab.In this study,we construct a new earthquake catalog for northern Chile using seismic waveforms assembled for the period of 2014-2019,from which 320,070 P-wave and 232,907 S-wave first arrivals are obtained for 25,763 earthquakes.Grid search location method NonLinLoc is applied to determine initial earthquake locations and double-difference location method is used to improve relative event locations.The distribution of earthquakes exhibits distinct patterns to the north and south of 21°S.There are many more earthquakes deeper than~150 km to the south of 21°S,while relatively fewer to the north.The intraslab earthquakes shallower than~80 km generally reveal a distinct double seismic zone,and the gap between the two seismic planes disappears at a depth of approximately~80 km,followed by a concentration of seismicity in the depth range of~80-150 km.In the deeper slab,there exist several seismicity clusters with distinct earthquake activities down to~300 km.These characteristics shown in slab seismicity are likely caused by different mechanisms and can be helpful for understanding the subduction process.展开更多
The Chilean Pampean flat slab subduction segment is characterized by the nearly horizontal subduction of the Nazca Plate within the depth range of 100-120 km.Numerous seismic tomography studies have been conducted to ...The Chilean Pampean flat slab subduction segment is characterized by the nearly horizontal subduction of the Nazca Plate within the depth range of 100-120 km.Numerous seismic tomography studies have been conducted to investigate its velocity structure;however,they have used only seismic body wave data or surface wave data.As a result,the existing velocity models in the region may have relatively large uncertainties.In this study,we use body wave arrival times from earthquakes occurring in central Chile between 2014 and 2019,as well as Rayleigh wave phase velocity maps at periods of 5-80 s from ambient noise empirical Green’s functions in Chile.By jointly using body wave arrival times and surface wave dispersion data,we refine the VS model and improve earthquake locations in the central Chile subduction zone.Compared with previous velocity models,our velocity model better reveals an eastward-dipping high-velocity plate representing the subducting Nazca Plate,which is 40-50 km thick and is more consistent with the slab thickness estimated by receiver function imaging and thermal modeling.Overall,the intraslab seismicity distribution spatially correlates well with the slab high-velocity anomalies except along the subduction paths of the CopiapóRidge and Juan Fernández Ridge.Additionally,parallel low-velocity stripes are imaged beneath the subducting plate,which are likely associated with the accumulated melts.The joint inversion velocity model also resolves widespread low-velocity anomalies in the crust beneath the Central Volcanic Zone of the central Andes,likely representing crustal magma chambers for various volcanoes.展开更多
Venetoclax(Vene),a BCL-2 inhibitor,is widely used as a chemotherapeutic drug in acute myeloid leukemia(AML).However,its treatment specificity for leukemia cells is limited,often leading to side effects and treatment r...Venetoclax(Vene),a BCL-2 inhibitor,is widely used as a chemotherapeutic drug in acute myeloid leukemia(AML).However,its treatment specificity for leukemia cells is limited,often leading to side effects and treatment resistance.In this study,we utilized L-phenylalanine as an efficient nanocarrier to enhance the delivery of Vene,forming the complex Vene@8P6.This complex was then applied to AML mouse models and human AML cell lines.The in vitro analysis showed that THP-1 and HL60 cells rapidly absorbed the Vene@8P6 nanoparticles.This absorption resulted in severe DNA damage,increased reactive oxygen species(ROS)production,elevated apoptosis rates,and decreased cell proliferation compared to the administration of Vene alone.In vivo studies demonstrated that Vene@8P6 more efficiently targeted leukemia cells than normal hematopoietic cells within the bone marrow and other major organs in AML mice,as evidenced by bioluminescence imaging and flow cytometry analysis.Furthermore,Vene@8P6 treatment resulted in reduced drug side effects and improved therapeutic efficacy in AML mice.Overall,Vene@8P6 represents a novel and efficient therapeutic agent for AML,offering enhanced leukemia target specificity,reduced side effects,and improved treatment outcomes.展开更多
Recent technological advances in miniaturization have allowed for a confocal scanning microscope to be integrated into a conventional flexible endoscope,or into trans-endoscopic probes,a technique now known as confoca...Recent technological advances in miniaturization have allowed for a confocal scanning microscope to be integrated into a conventional flexible endoscope,or into trans-endoscopic probes,a technique now known as confocal endomicroscopy or confocal laser endomicroscopy.This newly-developed technology has enabled endoscopists to collect real-time in vivo histological images or "virtual biopsies" of the gastrointestinal mucosa during endoscopy,and has stimulated significant interest in the application of this technique in clinical gastroenterology.This review aims to evaluate the current data on the technical aspects and the utility of this new technology in clinical gastroenterology and its potential impact in the future,particularly in the screening or surveillance of gastrointestinal neoplasia.展开更多
Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding prope...Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding property.Microstructures of Cu/Al interfaces were observed by OM,SEM and EDX Analyser in order to investigate the bonding properties of the material.According to the microstructure a series of diffusion layers were observed at the interface and the thicknesses of diffusion layers have increased with aging time as a result of the diffusion bonding.The interfaces were composed of 3-ply diffusion layers and their compositions were changed with aging time at 400 °C.These compositional compounds were revealed to be η2,(θ+η2),(α+θ) intermetallic phases.It is evident from V-notch impact tests that the growth of the brittle diffusion layers with the increasing aging time directly influenced delamination distance between the Cu sleeve and the Al core.It is suggested that the proper holding time at 400 °C for aging as post heat treatment of a drawn Cu/Al bar clad material would be within 1 h.展开更多
To study the uncertain optimization problems on implementation schedule, time-cost trade-off and quality in enterprise resource planning （ERP） implementation, combined with program evaluation and review technique （...To study the uncertain optimization problems on implementation schedule, time-cost trade-off and quality in enterprise resource planning （ERP） implementation, combined with program evaluation and review technique （PERT）, some optimization models are proposed, which include the implementation schedule model, the timecost trade-off model, the quality model, and the implementation time-cost-quality synthetic optimization model. A PERT-embedded genetic algorithm （GA） based on stochastic simulation technique is introduced to the optimization models solution. Finally, an example is presented to show that the models and algorithm are reasonable and effective, which can offer a reliable quantitative decision method for ERP implementation.展开更多
Automobile manufacturers have been inereasingl^r adopting hot-stamped parts for use in newly designed ve- hicles to improve crash worthiness and fuel efficiency. However, the simulation of hot stamping is rather compl...Automobile manufacturers have been inereasingl^r adopting hot-stamped parts for use in newly designed ve- hicles to improve crash worthiness and fuel efficiency. However, the simulation of hot stamping is rather complex and challenging, and further research still needs to be done on hot stamping hardening mechanism. The microstruc- ture evolution and hardening mechanisms during hot stamping of 22MnB5 steel were thoroughly investigated, using information provided in the literatures as well as experimental results. New models were developed to predict the grain growth during heating and the flow stress of a manganese boron steel （22MnB5） with high hardenability by the Gleeble simulation experimental results. The deformed austenite decomposition during stamping and quenching was emphatically quantified based on the transformation thermodynamic and kinetic theories, and the relationship of mi- crostructure to properties was analyzed. The results showed that the optimal process to obtain homogeneous and small lath martensite is heating at 900--950 ℃ for 5 min and then auenching at 50 ℃/s with a Dressing time about 8 s.展开更多
The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the sc...The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the scene are changed,the extracted background becomes bad until the transition is over. A novel adaptive method is presented to adjust the learning rate of GMM in a Hilbert space. The background extraction is treated as a process of approaching to a certain point in the Hilbert space,so the real-time learning rate can be obtained by calculating the distance between the two adjacent extracted background images,and a judgment method of the stability of background is got too. Compared with conventional GMM,the method has both high rapidness and good stability at the same time,and it can adjust the learning rate online. The experiment shows that it is better than conventional GMM,especially in the transition process of background extraction.展开更多
As underground excavations are getting deeper and field stresses increase, the behavior of intact rock blocks plays an increasingly important role in understanding and estimating the overall rock mass strength. To mod...As underground excavations are getting deeper and field stresses increase, the behavior of intact rock blocks plays an increasingly important role in understanding and estimating the overall rock mass strength. To model the brittle behavior of intact rock blocks, the stress–strain curve is usually idealized considering a linear strength mobilization approach(cohesion-weakening-friction-strengthening, CWFS),however, it is well recognized that rock presents a nonlinear behavior in terms of the confining stress.This study extends the strength mobilization in brittle failure of rock using nonlinear criteria. To determine the model parameters, a standard statistical method that uses the complete laboratory stress–strain curves of the intact rock is employed. Several hypotheses of linear and nonlinear models are statistically compared for different types of rock and confining stress levels. Results demonstrate that the best approach to model the brittle failure of rock is to consider a nonlinear strength envelope, such as the Hoek-Brown criterion assuming a residual uniaxial compressive strength different from zero and a mi parameter that increases, both with simultaneous mobilization. This model helps to recreate highconfining conditions and a more realistic transition between peak and post-peak strength. The obtained parameters are discussed and compared with literature values to verify the validity and to develop guidelines for the estimation of parameters, providing an objective mobilization criterion. Finally, the nonlinear model was applied to a finite element code and extended to a tunnel scale in the brittle rock under high-stress conditions. A reasonable fit between the simulations and the in-situ overbreak measurements was found.展开更多
基金supported by the National Natural Science Foundation of China(62271247)the Natural Science Foundation of Jiangsu Province(BK20240181)+4 种基金the Dreams Foundation of Jianghuai Advance Technology Center(2023-ZM01D001)the National Aerospace Science Foundation of China(20220055052001)the Qing Lan Project of Jiangsu Provincethe Fund of Prospective Layout of Scientific Research for Nanjing University of Aeronautics and Astronauticsthe Key Laboratory of Radar Imaging and Microwave Photonics(Nanjing University of Aeronautics and Astronautics),Ministry of Education。
文摘In this paper,the joint design of transmit and receive beamformers for transmit subaperturing multiple-input-multiple-output(TS-MIMO)radar is investigated,aiming to enhance its low probability of intercept(LPI)capability.The main objective is to simultaneously minimize the transmission power,suppress the transmit sidelobe levels,and minimize the probability of intercept,thus bolstering the LPI performance of the radar system while maintaining the desired target detection performance.An alternative optimization method is proposed to jointly optimize the transmit and receive beamformers,yielding an unified LPI optimization framework.Particularly,the proposed iterative algorithm based on the Lagrange duality theory for transmit beamforming is more efficient than the conventional convex optimization method.Numerical experiments highlight the effectiveness of the proposed approach in sidelobe suppression and computational efficiency.
基金sponsored by the National Key Scientific Instrument and Equipment Development Projects of China(Grant No.62027823)the National Natural Science Foun-dation of China(Grant No.61775048).
文摘In recent years,the use of deep learning to replace traditional numerical methods for electromagnetic propagation has shown tremendous potential in the rapid design of photonic devices.However,most research on deep learning has focused on single-layer grating couplers,and the accuracy of multi-layer grating couplers has not yet reached a high level.This paper proposes and demonstrates a novel deep learning network-assisted strategy for inverse design.The network model is based on a multi-layer perceptron(MLP)and incorporates convolutional neural networks(CNNs)and transformers.Through the stacking of multiple layers,it achieves a high-precision design for both multi-layer and single-layer raster couplers with various functionalities.The deep learning network exhibits exceptionally high predictive accuracy,with an average absolute error across the full wavelength range of 1300–1700 nm being only 0.17%,and an even lower predictive absolute error below 0.09%at the specific wavelength of 1550 nm.By combining the deep learning network with the genetic algorithm,we can efficiently design grating couplers that perform different functions.Simulation results indicate that the designed single-wavelength grating couplers achieve coupling efficiencies exceeding 80%at central wavelengths of 1550 nm and 1310 nm.The performance of designed dual-wavelength and broadband grating couplers also reaches high industry standards.Furthermore,the network structure and inverse design method are highly scalable and can be applied not only to multi-layer grating couplers but also directly to the prediction and design of single-layer grating couplers,providing a new perspective for the innovative development of photonic devices.
基金funded by the Research,Development,and Innovation Authority(RDIA)—Kingdom of Saudi Arabia—under supervision Energy,Industry,and Advanced Technologies Research Center,Taibah University,Madinah,Saudi Arabia with grant number(12979-iau-2023-TAU-R-3-1-EI-).
文摘The generation of high-quality 3D models from single 2D images remains challenging in terms of accuracy and completeness.Deep learning has emerged as a promising solution,offering new avenues for improvements.However,building models from scratch is computationally expensive and requires large datasets.This paper presents a transfer-learning-based approach for category-specific 3D reconstruction from a single 2D image.The core idea is to fine-tune a pre-trained model on specific object categories using new,unseen data,resulting in specialized versions of the model that are better adapted to reconstruct particular objects.The proposed approach utilizes a three-phase pipeline comprising image acquisition,3D reconstruction,and refinement.After ensuring the quality of the input image,a ResNet50 model is used for object recognition,directing the image to the corresponding category-specific model to generate a voxel-based representation.The voxel-based 3D model is then refined by transforming it into a detailed triangular mesh representation using the Marching Cubes algorithm and Laplacian smoothing.An experimental study,using the Pix2Vox model and the Pascal3D dataset,has been conducted to evaluate and validate the effectiveness of the proposed approach.Results demonstrate that category-specific fine-tuning of Pix2Vox significantly outperforms both the original model and the general model fine-tuned for all object categories,with substantial gains in Intersection over Union(IoU)scores.Visual assessments confirm improvements in geometric detail and surface realism.These findings indicate that combining transfer learning with category-specific fine tuning and refinement strategy of our approach leads to better-quality 3D model generation.
基金Natural Science Foundation of Chongqing under Grant No.CSTC2008BB7299.
文摘We studied the decomposition of two haloacetic acids(HAAs),dichloroacetic acid(DCAA)and trichloroacetic acid(TCAA),in water by single oxidants ozone(O3)and ultraviolet radiation(UV)and the advanced oxidation processes(AOPs)constituted by the combinations of O3/UV,H2O2/UV,O3/H2O2,and O3/H2O2/UV.The concentrations of HAAs were analyzed at specified time intervals to track their decomposition.Except for O3 and UV,the four combined oxidation processes remarkably enhance the decomposition of DCAA and TCAA owing to the generated very reactive hydroxyl radicals.The fastest decomposition process is O3/H2O2/UV,closely followed by O3/UV.DCAA is much easier to decompose than TCAA.The kinetics of HAA decomposition by O3/UV can be described well by a pseudo first-order reaction model under a constant initial dissolved O3 concentration and fixed UV radiation.Humic acids and HCO3-in the reaction system both decrease the decomposition rate constants for DCAA and TCAA.The amount of H2O2 accumulates in the presence of humic acids in the O3/UV process.
基金supported by the National Aeronautics and Space Administration(Grant No.80NSSC20K0914)the Lockheed Martin Internal Research Funds(IRAD).
文摘We demonstrate a silicon nitride photonics-based imaging system that can perform one-dimensional interferometric imaging around the 1550-nm wavelength.The magnetograph using interferometric and computational imaging for remote observations(MICRO)design uses silicon nitride on a Si platform to replace the bulky free-space optics of traditional magnetograph imaging systems with nanofabricated structures of a fraction of the size.The photonic integrated circuit(PIC)uses an array of lenslets that couple light into four input waveguides with spacing arranged along a Golomb ruler,where each aperture pair formed has a unique length.Each aperture is mixed with a 13-dBm reference laser and separated inside a 2×4 optical hybrid to generate in-phase and quadrature-phase signals to be detected in balanced detectors at the output of the PIC.We use a field programmable gate array(FPGA)board to digitize and process the measurements.The FPGAs and PIC are combined to reduce the overall size,weight,and power of the system,paving the way for a compact imaging system.We demonstrate a PIC-based imager design and experimental testbed for spectrometry applications.
基金Supported by New Chongqing Innovative Young Talent Project(Grant No.2024NSCQ-qncxX0468)Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX1283)Dreams Foundation of Jianghuai Advanced Technology Center(Grant No.2023-ZM01Z007).
文摘Jumping robots are highly capable of overcoming obstacles.However,their explosive force,short duration,and variable trajectories pose significant challenges in achieving stable landings in complex environments.Traditional approaches rely heavily on sophisticated algorithms and electronic sensor feedback systems to ensure landing stability,which increases the implementation complexity.Inspired by the process by which humans complete jumps and achieve stable landings in complex environments,this study proposes a novel landing control method for jumping robots.By designing a mechanically coupled perception-control structure based on mechanical logic computing,the robot simulates the real-time transmission of neural signals triggered by the ground reaction force(GRF)in human reflex loops,thereby simplifying traditional control approaches.Through the collaboration of a flexible mechanical spine and a bistable foot module,the robot achieves an average height of 16.8 cm and a distance of 25.36 cm in consecutive stable jumps.It also demonstrates reliable landing performance on challenging terrain including slopes and cobblestone surfaces.This paper proposes a novel landing control method for jumping robots that simplifies traditional control approaches.The method enables stable landings on complex terrain through a mechanically coupled perception-control structure.This approach has potential applications in tasks requiring mobility over uneven terrain,such as search and rescue.
基金supported by the National Natural Science Foundation of China(Nos.62273127 and 62073217)the Dreams Foundation of Jianghuai Advance Technology Center(No.2023-ZM01J006)the Anhui Provincial Key Research and Development Project(No.2022a05020025).
文摘The output regulation approach has effectively addressed the speed tracking and disturbance rejection problem of permanent magnet synchronous motor(PMSM).Although accurate speed tracking under time-varying load torque disturbance has been achieved,the number of disturbance frequencies should be known.In this paper,an adaptive observer-based error feedback control method is proposed,which can solve the speed tracking control problem of PMSM subject to completely unknown multi-frequency sinusoidal load torque disturbance,requiring only the upper bound of the number of disturbance frequencies.The design steps of this method can be divided into the following three steps.In step one,a filtered transformation is applied to convert the observer canonical form of the error system and the transformed exosystem into an adaptive observer form.In step two,an adaptive observer is designed to estimate the unknown parameters of the exosystem and states of the adaptive observer form.In step three,an adaptive observer-based error feedback controller is designed to solve this control problem.The effectiveness of the proposed method is demonstrated by experimental results.
基金the financial support from the National Key R&D Program of China(2022YFA1504200)the Zhejiang Provincial Natural Science Foundation(No.LR22B060003)+2 种基金the National Natural Science Foundation of China(22322810,22078293,22141001,and 22008211)the Fundamental Research Funds for the Provincial Universities of Zhejiang(RF-C2023004)the Midea Group-Zhejiang University of Technology Joint Development Funding(KYY-HX-20240263)。
文摘The anodic electrochemical ozone production(EOP)and the cathodic three-electron oxygen reduction reaction(3e^(-)ORR)are effective processes for generating active oxygen species(ROS).However,the activation of ozone(O_(3))by hydroxyl radical(OH)to form ROS poses significant challenges.The micelle balllike bimetallic La-Nb oxides(LNOx)have been developed as a bifunctional electrocatalyst for both the EOP and 3e^(-)ORR reactions.The LNO20 demonstrated a 9.8%of Faradaic efficiency(FE)in O_(3)production and a transfer number of 2.8 electrons in the 3e^(-)ORR.Theoretical calculations support the notion that the five-membered ring mechanism in LNO20 facilitates O_(3)production.Additionally,the incorporation of La provides active sites that enhance the activation of hydrogen peroxide(^(*)H_(2)O_(2))and the generation of OH.This innovative approach synergistically integrates EOP and 3e^(-)ORR,enhancing the activation of O_(3)to produce ROS,demonstrating exceptional efficacy in the degradation of organic pollutants and antimicrobial activity.The study paves the way for designing advanced electrocatalysts for EOP and 3e^(-)ORR and offers insights into utilizing electrochemical method to support other antibacterial strategies.
基金financial support from the National Key R&D Program of China (No. 2021YFB3800102)the Key Research Project of Hefei Normal University (No. 2023QN08)+2 种基金National Natural Science Foundation of China (Nos. U22A20142, 52302324, and 52272252)CASHIPS Director's Fund (Nos. YZJJ-GGZX-2022-01 and YZJJ202304-CX)Dreams Foundation of Jianghuai Advance Technology Center (No. 2023-ZM01X011)。
文摘Interfacial defects and environmental instability at perovskite surfaces pose significant challenges for inverted perovskite solar cells(PSCs). Surface post-treatment strategies have emerged as a viable approach to improve film quality and passivate defects. Although organic molecules can passivate both surfaces and grain boundaries via hydrogen or covalent bonding,their limited adsorption specificity often results in incomplete defect neutralization. In this work, we introduce a bilayer passivation approach employing phenethylammonium iodide(PEAI) and n-octylammonium iodide(OAI) to concurrently mitigate nonradiative recombination and improve stability. PEAI passivates undercoordinated Pb^(2+) at grain boundaries and surfaces, effectively eliminating deep-level traps and suppressing non-radiative losses. Meanwhile, OAI forms a hydrophobic barrier on the perovskite surface through its long alkyl chains, inhibiting moisture penetration without compromising interfacial charge transport. As a result, the perovskite film exhibits significantly enhanced optoelectronic performance and environmental stability,achieving a champion power conversion efficiency(PCE) of 24.48%.
基金supported by National Natural Science Foundation of China(No.41861134009)the PIA ANID(AFB180004)the ANID(PCI PII-180003).
文摘The Chilean subduction zone is one of the most seismically active regions globally,characterized by extensive intermediatedepth seismicity in the slab.In this study,we construct a new earthquake catalog for northern Chile using seismic waveforms assembled for the period of 2014-2019,from which 320,070 P-wave and 232,907 S-wave first arrivals are obtained for 25,763 earthquakes.Grid search location method NonLinLoc is applied to determine initial earthquake locations and double-difference location method is used to improve relative event locations.The distribution of earthquakes exhibits distinct patterns to the north and south of 21°S.There are many more earthquakes deeper than~150 km to the south of 21°S,while relatively fewer to the north.The intraslab earthquakes shallower than~80 km generally reveal a distinct double seismic zone,and the gap between the two seismic planes disappears at a depth of approximately~80 km,followed by a concentration of seismicity in the depth range of~80-150 km.In the deeper slab,there exist several seismicity clusters with distinct earthquake activities down to~300 km.These characteristics shown in slab seismicity are likely caused by different mechanisms and can be helpful for understanding the subduction process.
基金funded by the National Natural Science Foundation of China under Grant 42230101the National Agency for Research and Development of Chile(ANID)by Projects AFB180004 and AFB220002the ANID Programa de Cooperación Internacional(PCI)Grant PII-180003.
文摘The Chilean Pampean flat slab subduction segment is characterized by the nearly horizontal subduction of the Nazca Plate within the depth range of 100-120 km.Numerous seismic tomography studies have been conducted to investigate its velocity structure;however,they have used only seismic body wave data or surface wave data.As a result,the existing velocity models in the region may have relatively large uncertainties.In this study,we use body wave arrival times from earthquakes occurring in central Chile between 2014 and 2019,as well as Rayleigh wave phase velocity maps at periods of 5-80 s from ambient noise empirical Green’s functions in Chile.By jointly using body wave arrival times and surface wave dispersion data,we refine the VS model and improve earthquake locations in the central Chile subduction zone.Compared with previous velocity models,our velocity model better reveals an eastward-dipping high-velocity plate representing the subducting Nazca Plate,which is 40-50 km thick and is more consistent with the slab thickness estimated by receiver function imaging and thermal modeling.Overall,the intraslab seismicity distribution spatially correlates well with the slab high-velocity anomalies except along the subduction paths of the CopiapóRidge and Juan Fernández Ridge.Additionally,parallel low-velocity stripes are imaged beneath the subducting plate,which are likely associated with the accumulated melts.The joint inversion velocity model also resolves widespread low-velocity anomalies in the crust beneath the Central Volcanic Zone of the central Andes,likely representing crustal magma chambers for various volcanoes.
基金the National Natural Science Foundation of China(No.52173150 to J.Wu)the National Natural Science Foundation of China(No.82370164 to C.Chen)+5 种基金Guangzhou Science and Technology Program City-University Joint Funding Project(No.2023A03J0001 to J.Wu)the Affiliated Qingyuan Hospital of Guangzhou Medical University Open Project Fund(No.202301–211 to J.Wu)Sanming Project of Medicine in Shenzhen(No.SZSM201911004 to D.Lin and M.Zhao)National Natural Science Foundation of China(No.92268205 to D.Lin)Doctoral Scientific Research Foundation of Changzhi Medical College,China(to Z.Zhao)Post-doctoral Science Foundation(No.2022M723670 to L.Wang)。
文摘Venetoclax(Vene),a BCL-2 inhibitor,is widely used as a chemotherapeutic drug in acute myeloid leukemia(AML).However,its treatment specificity for leukemia cells is limited,often leading to side effects and treatment resistance.In this study,we utilized L-phenylalanine as an efficient nanocarrier to enhance the delivery of Vene,forming the complex Vene@8P6.This complex was then applied to AML mouse models and human AML cell lines.The in vitro analysis showed that THP-1 and HL60 cells rapidly absorbed the Vene@8P6 nanoparticles.This absorption resulted in severe DNA damage,increased reactive oxygen species(ROS)production,elevated apoptosis rates,and decreased cell proliferation compared to the administration of Vene alone.In vivo studies demonstrated that Vene@8P6 more efficiently targeted leukemia cells than normal hematopoietic cells within the bone marrow and other major organs in AML mice,as evidenced by bioluminescence imaging and flow cytometry analysis.Furthermore,Vene@8P6 treatment resulted in reduced drug side effects and improved therapeutic efficacy in AML mice.Overall,Vene@8P6 represents a novel and efficient therapeutic agent for AML,offering enhanced leukemia target specificity,reduced side effects,and improved treatment outcomes.
文摘Recent technological advances in miniaturization have allowed for a confocal scanning microscope to be integrated into a conventional flexible endoscope,or into trans-endoscopic probes,a technique now known as confocal endomicroscopy or confocal laser endomicroscopy.This newly-developed technology has enabled endoscopists to collect real-time in vivo histological images or "virtual biopsies" of the gastrointestinal mucosa during endoscopy,and has stimulated significant interest in the application of this technique in clinical gastroenterology.This review aims to evaluate the current data on the technical aspects and the utility of this new technology in clinical gastroenterology and its potential impact in the future,particularly in the screening or surveillance of gastrointestinal neoplasia.
基金Project supported by the Fundamental Materials Development funded by the Korean Ministry of Knowledge Economy
文摘Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding property.Microstructures of Cu/Al interfaces were observed by OM,SEM and EDX Analyser in order to investigate the bonding properties of the material.According to the microstructure a series of diffusion layers were observed at the interface and the thicknesses of diffusion layers have increased with aging time as a result of the diffusion bonding.The interfaces were composed of 3-ply diffusion layers and their compositions were changed with aging time at 400 °C.These compositional compounds were revealed to be η2,(θ+η2),(α+θ) intermetallic phases.It is evident from V-notch impact tests that the growth of the brittle diffusion layers with the increasing aging time directly influenced delamination distance between the Cu sleeve and the Al core.It is suggested that the proper holding time at 400 °C for aging as post heat treatment of a drawn Cu/Al bar clad material would be within 1 h.
基金the National High-Tech. R & D Program for CIMS, China (2003AA413210).
文摘To study the uncertain optimization problems on implementation schedule, time-cost trade-off and quality in enterprise resource planning （ERP） implementation, combined with program evaluation and review technique （PERT）, some optimization models are proposed, which include the implementation schedule model, the timecost trade-off model, the quality model, and the implementation time-cost-quality synthetic optimization model. A PERT-embedded genetic algorithm （GA） based on stochastic simulation technique is introduced to the optimization models solution. Finally, an example is presented to show that the models and algorithm are reasonable and effective, which can offer a reliable quantitative decision method for ERP implementation.
基金Item Sponsored by Major Project of Ministry of Industry and Information Technology of China(2009ZX04014-072)Basic Research Project of Jilin University of China(200903019)
文摘Automobile manufacturers have been inereasingl^r adopting hot-stamped parts for use in newly designed ve- hicles to improve crash worthiness and fuel efficiency. However, the simulation of hot stamping is rather complex and challenging, and further research still needs to be done on hot stamping hardening mechanism. The microstruc- ture evolution and hardening mechanisms during hot stamping of 22MnB5 steel were thoroughly investigated, using information provided in the literatures as well as experimental results. New models were developed to predict the grain growth during heating and the flow stress of a manganese boron steel （22MnB5） with high hardenability by the Gleeble simulation experimental results. The deformed austenite decomposition during stamping and quenching was emphatically quantified based on the transformation thermodynamic and kinetic theories, and the relationship of mi- crostructure to properties was analyzed. The results showed that the optimal process to obtain homogeneous and small lath martensite is heating at 900--950 ℃ for 5 min and then auenching at 50 ℃/s with a Dressing time about 8 s.
文摘The rapidness and stability of background extraction from image sequences are incompatible,that is,when a conventional Gaussian mixture models (GMM)is used to rebuild the background,if the background regions of the scene are changed,the extracted background becomes bad until the transition is over. A novel adaptive method is presented to adjust the learning rate of GMM in a Hilbert space. The background extraction is treated as a process of approaching to a certain point in the Hilbert space,so the real-time learning rate can be obtained by calculating the distance between the two adjacent extracted background images,and a judgment method of the stability of background is got too. Compared with conventional GMM,the method has both high rapidness and good stability at the same time,and it can adjust the learning rate online. The experiment shows that it is better than conventional GMM,especially in the transition process of background extraction.
基金the financial support from basal CONICYT project AFB-180004 of the Advanced Mining Technology Center (AMTC) - University of Chile。
文摘As underground excavations are getting deeper and field stresses increase, the behavior of intact rock blocks plays an increasingly important role in understanding and estimating the overall rock mass strength. To model the brittle behavior of intact rock blocks, the stress–strain curve is usually idealized considering a linear strength mobilization approach(cohesion-weakening-friction-strengthening, CWFS),however, it is well recognized that rock presents a nonlinear behavior in terms of the confining stress.This study extends the strength mobilization in brittle failure of rock using nonlinear criteria. To determine the model parameters, a standard statistical method that uses the complete laboratory stress–strain curves of the intact rock is employed. Several hypotheses of linear and nonlinear models are statistically compared for different types of rock and confining stress levels. Results demonstrate that the best approach to model the brittle failure of rock is to consider a nonlinear strength envelope, such as the Hoek-Brown criterion assuming a residual uniaxial compressive strength different from zero and a mi parameter that increases, both with simultaneous mobilization. This model helps to recreate highconfining conditions and a more realistic transition between peak and post-peak strength. The obtained parameters are discussed and compared with literature values to verify the validity and to develop guidelines for the estimation of parameters, providing an objective mobilization criterion. Finally, the nonlinear model was applied to a finite element code and extended to a tunnel scale in the brittle rock under high-stress conditions. A reasonable fit between the simulations and the in-situ overbreak measurements was found.
