BACKGROUND Non-proliferative diabetic retinopathy(NPDR)poses a significant challenge in diabetes management due to its microvascular changes in the retina.Laser photocoagulation,a conventional therapy,aims to mitigate...BACKGROUND Non-proliferative diabetic retinopathy(NPDR)poses a significant challenge in diabetes management due to its microvascular changes in the retina.Laser photocoagulation,a conventional therapy,aims to mitigate the risk of progressing to proliferative diabetic retinopathy(PDR).AIM To compare the efficacy and safety of multi-spot vs single-spot scanning panretinal laser photocoagulation in NPDR patients.METHODS Forty-nine NPDR patients(86 eyes)treated between September 2020 and July 2022 were included.They were randomly allocated into single-spot(n=23,40 eyes)and multi-spot(n=26,46 eyes)groups.Treatment outcomes,including bestcorrected visual acuity(BCVA),central macular thickness(CMT),and mean threshold sensitivity,were assessed at predetermined intervals over 12 months.Adverse reactions were also recorded.RESULTS Energy levels did not significantly differ between groups(P>0.05),but the multi-spot group exhibited lower energy density(P<0.05).BCVA and CMT improvements were noted in the multi-spot group at one-month posttreatment(P<0.05).Adverse reaction incidence was similar between groups(P>0.05).CONCLUSION While energy intensity and safety were comparable between modalities,multi-spot scanning demonstrated lower energy density and showed superior short-term improvements in BCVA and CMT for NPDR patients,with reduced laser-induced damage.展开更多
The detonation wave-aiming warhead can effectively enhance the lethality efficiency. In the past, rules for casing rupture and velocity distribution under asymmetrical initiations were not adequately investigated. In ...The detonation wave-aiming warhead can effectively enhance the lethality efficiency. In the past, rules for casing rupture and velocity distribution under asymmetrical initiations were not adequately investigated. In this study, X-ray photography and numerical modelling are used to examine the casing expansions under centre point, asymmetrical one-point, and asymmetrical two-point(with central angles of 45° and 90°) initiations. The results indicate that early casing ruptures are caused by local high pressures, induced by the initiation, detonation wave interaction, and Mach wave onset. The fragment shapes are controlled by the impact angle of the detonation wave. The fragment velocity distributions differ under different initiation types, and the end rarefaction waves can affect the velocity distribution.This study can serve as a reference for the design and optimization of high-efficiency warheads.展开更多
During ship operations,frequent heave movements can pose significant challenges to the overall safety of the ship and completion of cargo loading.The existing heave compensation systems suffer from issues such as dead...During ship operations,frequent heave movements can pose significant challenges to the overall safety of the ship and completion of cargo loading.The existing heave compensation systems suffer from issues such as dead zones and control system time lags,which necessitate the development of reasonable prediction models for ship heave movements.In this paper,a novel model based on a time graph convolutional neural network algorithm and particle swarm optimization algorithm(PSO-TGCN)is proposed for the first time to predict the multipoint heave movements of ships under different sea conditions.To enhance the dataset's suitability for training and reduce interference,various filter algorithms are employed to optimize the dataset.The training process utilizes simulated heave data under different sea conditions and measured heave data from multiple points.The results show that the PSO-TGCN model predicts the ship swaying motion in different sea states after 2 s with 84.7%accuracy,while predicting the swaying motion in three different positions.By performing a comparative study,it was also found that the present method achieves better performance that other popular methods.This model can provide technical support for intelligent ship control,improve the control accuracy of intelligent ships,and promote the development of intelligent ships.展开更多
In this paper, a general family of derivative-free n + 1-point iterative methods using n + 1 evaluations of the function and a general family of n-point iterative methods using n evaluations of the function and only o...In this paper, a general family of derivative-free n + 1-point iterative methods using n + 1 evaluations of the function and a general family of n-point iterative methods using n evaluations of the function and only one evaluation of its derivative are constructed by the inverse interpolation with the memory on the previous step for solving the simple root of a nonlinear equation. The order and order of convergence of them are proved respectively. Finally, the proposed methods and the basins of attraction are demonstrated by the numerical examples.展开更多
The purpose of this work was to explore the influence law of vibration load on rock mass structure and slope stability.Based on the type and transmission way of vibration stress wave,the main stress in the horizontal ...The purpose of this work was to explore the influence law of vibration load on rock mass structure and slope stability.Based on the type and transmission way of vibration stress wave,the main stress in the horizontal and vertical directions was analyzed and the superposition effect of the stress wave was revealed.After the mechanical analysis of the sliding mass,the calculation formulas of the anti-sliding force and the sliding force were derived and the damage mechanism of blasting vibration to the structural plane was defined.In addition,according to the structure and lithologic parameter of the slope as well as the vibration monitoring data,the west slope stability of Xiaolongtan open pit mine was analyzed.The results show that the time-dependent stability factor is proportional to the vibration speed and the peak values appear at the same time.Vibration load promotes the breakage of the structural plane leading to the drop of the west slope stability factor by 0.23%.Under the multipoint simultaneous blasting,the fluctuating laws of the stability factors are consistent.The more the start-up points are,the higher the weakening degree to the slope stability is.Under the multipoint allochronic blasting,the stability factor depends on the synthetic waveform structure of all vibration waves.The greater the blasting time difference is,the lower the weakening degree to the slope stability is.Selecting the reasonable quantity of start-up points and time difference could fully reduce the adverse influence of vibration load to slope stability.展开更多
The study of multipoint blank holder force（BHF） control is carried out for hydroforming a complicated shape motorcycle fuel tank. By finite element method （FEM） simulation, the configuration of multipoint blank ho...The study of multipoint blank holder force（BHF） control is carried out for hydroforming a complicated shape motorcycle fuel tank. By finite element method （FEM） simulation, the configuration of multipoint blank holder cylinders and the setting of local BHF are optimized, and the influences of the multipoint BHF on the hydromechanical deep drawing and conventional hydroforming processes are studied. The desired fluid pressure and whole BHF are predicted for hydromechanical deep drawing process. Finally, simulation results are testified by forming experiment, and they are in agreement very well.展开更多
The neutron flux monitor(NFM)system is an important diagnostic subsystem introduced by large nuclear fusion devices such as international thermonuclear experimental reactor(ITER),Japan torus-60,tokamak fusion test rea...The neutron flux monitor(NFM)system is an important diagnostic subsystem introduced by large nuclear fusion devices such as international thermonuclear experimental reactor(ITER),Japan torus-60,tokamak fusion test reactor,and HL-2 A.Neutron fluxes can provide real-time parameters for nuclear fusion,including neutron source intensity and fusion power.Corresponding to different nuclear reaction periods,neutron fluxes span over seven decades,thereby requiring electronic devices to operate in counting and Campbelling modes simultaneously.Therefore,it is crucial to design a real-time NFM system to encompass such a wide dynamic range.In this study,a high-precision NFM system with a wide measurement range of neutron flux is implemented using realtime multipoint linear calibration.It can automatically switch between counting and Campbelling modes with variations in the neutron flux.We established a testing platform to verify the feasibility of the NFM system,which can output the simulated neutron signal using an arbitrary waveform generator.Meanwhile,the accurate calibration interval of the Campbelling mode is defined well.Based on the above-mentioned design,the system satisfies the requirements,offering a dynamic range of 10~8 cps,temporal resolution of 1 ms,and maximal relative error of 4%measured at the signal-to-noise ratio of 15.8 dB.Additionally,the NFM system is verified in a field experiment involving HL-2 A,and the measured neutron flux is consistent with the results.展开更多
We describe a system for multipoint videoconferencing that offers extremely low end-to-end delay, low cost and complexity, and high scalability, alongside standard features associated with high-end solutions such as r...We describe a system for multipoint videoconferencing that offers extremely low end-to-end delay, low cost and complexity, and high scalability, alongside standard features associated with high-end solutions such as rate matching and per- sonal video layout. The system accommodates heterogeneous receivers and networks based on the Internet Protocol and relies on scalable video coding to provide a coded representation of a source video signal at multiple temporal and spatial resolutions as well as quality levels. These are represented by distinct bitstream components which are created at each end-user encoder. Depending on the specific conferencing environment, some or all of these components are transmitted to a Scalable Video Conferencing Server (SVCS). The SVCS redirects these components to one or more recipients depending on, e.g., the available network con- ditions and user preferences. The scalable aspect of the video coding technique allows the system to adapt to different network conditions, and also accommodates different end-user requirements (e.g., a user may elect to view another user at a high or low spatial resolution). Performance results concerning flexibility, video quality and delay of the system are presented using the Joint Scalable Video Model (JSVM) of the forthcoming SVC (H.264 Annex G) standard, demonstrating that scalable coding outper- forms existing state-of-the-art systems and offers the right platform for building next-generation multipoint videoconferencing systems.展开更多
The static modeling and dynamic simulation are essential and critical processes in petroleum exploration and development. In this study, lithofacies models for Wabiskaw Member in Athabasca, Canada are generated by mul...The static modeling and dynamic simulation are essential and critical processes in petroleum exploration and development. In this study, lithofacies models for Wabiskaw Member in Athabasca, Canada are generated by multipoint statistics(MPS) and then compared with the models built by sequential indicator simulation(SIS). Three training images(Tls) are selected from modern depositional environments;the Orinoco River Delta estuary, Cobequid bay-Salmon River estuary, and Danube River delta environment. In order to validate lithofacies models, average and variance of similarity in lithofacies are calculated through random and zonal blind-well tests.In random six-blind-well test, similarity average of MPS models is higher than that of SIS model. The Salmon MPS model closely resembles facies pattern of Wabiskaw Member in subsurface. Zonal blind-well tests show that successful lithofacies modeling for transitional depositional setting requires additional or proper zonation information on horizontal variation, vertical proportion, and secondary data.As Wabiskaw Member is frontier oilsands lease, it is impossible to evaluate the economics from production data or dynamic simulation. In this study, a dynamic steam assisted gravity drainage(SAGD)performance indicator(SPIDER) on the basis of reservoir characteristics is calculated to build 3 D reservoir model for the evaluation of the SAGD feasibility in Wabiskaw Member. SPIDER depends on reservoir properties, economic limit of steam-oil ratio, and bitumen price. Reservoir properties like porosity,permeability, and water saturation are measured from 13 cores and calculated from 201 well-logs. Three dimensional volumes of reservoir properties are constructed mostly based on relationships among properties. Finally, net present value(NPV) volume can be built by equation relating NPV and SPIDER. The economic area exceeding criterion of US$ 10,000 is identified, and the ranges of reservoir properties are estimated. NPV-volume-generation workflow from reservoir parameter to static model provides costand time-effective method to evaluate the oilsands SAGD project.展开更多
Measurement-device-independent quantum key distribution(MDI-QKD) offers a practical way to realize a startype quantum network. Previous experiments on MDI-QKD networks can only support the point-to-point communication...Measurement-device-independent quantum key distribution(MDI-QKD) offers a practical way to realize a startype quantum network. Previous experiments on MDI-QKD networks can only support the point-to-point communication. We experimentally demonstrate a plug-and-play MDI-QKD network which can support the pointto-multipoint communication among three users. Benefiting from the plug-and-play MDI-QKD architecture,the whole network is automatically stabilized in spectrum, polarization, arrival time, and phase reference. The users only need the encoding devices, which means that the hardware requirements are greatly reduced. Our experiment shows that it is feasible to establish a point-to-multipoint MDI-QKD network.展开更多
A compact, low cost, multipoint Thomson scattering diagnostic system for HT-7 superconducting tokamak has been in operation since 1999. Its capability of measuring electron temperatures is in the range of 200 eV to 2 ...A compact, low cost, multipoint Thomson scattering diagnostic system for HT-7 superconducting tokamak has been in operation since 1999. Its capability of measuring electron temperatures is in the range of 200 eV to 2 keV at a density of a few times IO12 cm-3, with a spatial resolution of 2.4 cm for 5 spatial points and a temporal resolution of 1 ms-1 s for 8 time points. The main components of the diagnostic system include a 20-25 J Nd: glass laser with 35 ns pulse width (8 pulses per burst), a KDP frequency-doubling unit, spherical mirrors of multipass input optical system, a wide-angle collection objective, a bandpass glass filter for reducing the stray light to zero a f/2.5 polychromator, a fiberglass collimator, a photomultiplier's box with electronic preamplifier, high gain and high signal/noise ratio, CAMAC data acquisition and so on. The multipass optical system has been successful at increasing the quantity of scattered photons by passing the probing laser beam 10 times through the plasma under investigation. The HT7 Thomson scattering diagnostic has provided successfully the information on two-dimensional electron temperature in the plasma of HT-7 tokamak with LHCD and IBW.展开更多
The multipoint steam injection string of the horizontal well is a commonly used downhole component for high efficiency steam injection of the thermal recovery horizontal well. A reasonable layout of the valves to ensu...The multipoint steam injection string of the horizontal well is a commonly used downhole component for high efficiency steam injection of the thermal recovery horizontal well. A reasonable layout of the valves to ensure an even steam output of each point is still not well designed. At present, a general design method which is urgently necessary isn＇ t applied by each factory. According to the balance relationship of the momentum, the energy and the mass of the fluid flowing in the string, the pressure distribution equation of the fluid flowing in the multipoint steam injection string is built. On the basis of this equation, the design calculation method of the multipoint steam injection string is come up with. A specific example is given in the paper. Study shows that, with the equation built in this paper, the string can be designed with each axial valve having the same output, so that the technical demand of an even steam injection of the horizontal well section can be met.展开更多
A multipoint excitation experiment system of the 1Cr18Ni9 steel plate-pipe network as the main vibration body was established,which used transient flow produced by the wave exciter to excite the 1Cr18Ni9 steel plate-p...A multipoint excitation experiment system of the 1Cr18Ni9 steel plate-pipe network as the main vibration body was established,which used transient flow produced by the wave exciter to excite the 1Cr18Ni9 steel plate-pipe network to vibrate.The experimental results show that the 1Cr18Ni9 steel plate vibrates in three dimensions.The vibrations of the particles of the steel plate distributing along the pipe＇s axial have phase differences and take place near the cylinder side first.Therefore,it is a multipoint vibration mode.The amplitude of the 1Cr18Ni9 steel plate increases as the system pressure increases and decreases as the wave exciter＇s frequency decreases.The vibration intensity of the particles of the 1Cr18Ni9 steel plate close to the cylinder is the strongest and the amplitude is the highest in Y direction at a given system frequency.The vibration intensity of the particles close to the wave exciter is the strongest and the amplitude is the smallest in Z direction at a given system pressure.展开更多
In order to improve the power of initiating explosive warheads, besides exploring new type of high explosive, multipoint initiation technology becomes the research focus. With research on electronic safety and arming ...In order to improve the power of initiating explosive warheads, besides exploring new type of high explosive, multipoint initiation technology becomes the research focus. With research on electronic safety and arming devices （ESADs）, pulse power devices and slapper detonators, a hardware control circuit was designed for multipoint initiation control system based on complex programmable logic device （ CPLD ）. In addition, a real-time monitoring interface based on virtual instru- ments technology was designed by the prevailing software of Laboratory Virtual Instrument Engineer- ing Workbench （LabVIEW）. It provides users a real-time status of the hardware circuit system. Mo- reover, a series of experiments were done on the software and hardware platform. The results show that the signals transmission, collection, analysis and display can be realized reliably through a serial port line. It is verified that using a serial bus controller for multiple initiators is reasonable. Successful design of the platform will play an important foundation for the theory and engineering of the fu- ture weapon system. Surely, it will become one of the development directions for intelligent initia- tion system.展开更多
A collocation method with multipoint weighting is presented in this paper.Itconverges as rapidly as the Galerkin method hut needs less computation effort.By means ofthe technique with Gauss points(superconvergence poi...A collocation method with multipoint weighting is presented in this paper.Itconverges as rapidly as the Galerkin method hut needs less computation effort.By means ofthe technique with Gauss points(superconvergence points)as the collocating points,dipole anddipole array are analyzed,and the numerical results are in good agreement with those given inrelative references.展开更多
Given a regular compact set E in , a unit measure μ supported by , a triangular point set , and a function f , holomorphic on E , let πβ,fn,m be the associated multipoint β-Padé approximant of order (n,m) . W...Given a regular compact set E in , a unit measure μ supported by , a triangular point set , and a function f , holomorphic on E , let πβ,fn,m be the associated multipoint β-Padé approximant of order (n,m) . We show that if the sequence πβ,fn,m , n∈Λ , ∧∈n,k are uniformly distributed on with respect to u as n∈Λ . Furthermore, a result about the behavior of the zeros of the exact maximally convergent sequence Λ is provided, under the condition that Λ is “dense enough”.展开更多
The VC merging algorithm is used widely for multipoint to point ATM communication. For AAL5 lacking multiplex ID field, the downstream receiving point cannot distinguish the multiplexed source in a multipoint to point...The VC merging algorithm is used widely for multipoint to point ATM communication. For AAL5 lacking multiplex ID field, the downstream receiving point cannot distinguish the multiplexed source in a multipoint to point VC after VC merging. So the source based rate distribution algorithms cannot work properly. We designed a source detection algorithm to enable the switch to know the number of sources and the cell rate of each source in a multipoint to point VC. These information is very important for the source based rate distribution algorithm. We used the ERICA algorithm in our simulations and the simulations demonstrated the proper operation of the source detection algorithm.展开更多
Based on massive MIMO （ multiple-input multiple-output） （M2M） systems, in order to avoid pilot contamination and improve the performance of rapacity, a pilot training transmission scheme was designed for pilot dec...Based on massive MIMO （ multiple-input multiple-output） （M2M） systems, in order to avoid pilot contamination and improve the performance of rapacity, a pilot training transmission scheme was designed for pilot decontamination by utilizing orthogonal mbearriers of OFDM （ orthogonal frequency division multiplexing） during pilot transmission phase and a joint optimized transceiver design for multi-antenna user pairs was proposed during the data transmission phase. The massive M2M system included a single relay station, multiple paired source nodes and destination nodes. Source nodes precoding matrices and relay station precoding matrix were jointly optimized by maximizing the weighted sum-rate in OFDM systems. After some mathematical manipulation to sum-rate, the cost function of sum.rate was expressed as quadratic optimizing expressions which could be solved by regular convex optlmiTation softwares. Different from existing algorithms, the proposed precoding design was based on massive MIMO OFDM systems with multi-antenna users pairs together pilot decontamination transmission arrangement. Simulations indicate the effectiveness of the proposed optimal precoding system. The proposed scheme not only can reduce pilot contamination, but also can improve performance of bit-error-rate （BER） as wed as sum- rate contrast to existing algorithms. In addition, it shows that the proposed M2M massive MIMO system works steadily when the number of users increases in large scale.展开更多
Technology-assisted ball training systems have become a research hotspot due to their ability to provide quantitative data for guiding athletes to address their areas of improvement.However,traditional tennis training...Technology-assisted ball training systems have become a research hotspot due to their ability to provide quantitative data for guiding athletes to address their areas of improvement.However,traditional tennis training systems still have some limitations;for instance,they are subjective,expensive,heavy,and time-consuming.In this research,an assistant training tennis racket,which consists of arrayed flexible sensors and an inertial measurement unit,has been proposed to comprehensively analyze the representative actions’force and acceleration.Consisting of MXene as the sensitive material and melamine sponge as the substrate(named MMSS),the flexible sensor exhibited an excellent sensitivity of 5.35 kPa^(-1)(1.1-22.2 kPa)due to the formation of a 3D conductive network.Moreover,the sensor retained a high sensitivity of 0.6 k Pa-1in an ultrawide measurement range(22.2-266 kPa).In addition to recognizing the type of hitting action,an artificial intelligence algorithm was introduced to accurately differentiate the five typical motion behaviors with an accuracy rate of 98.2%.This study not only proposes a comprehensive assistant training tennis racket for improving the techniques of tennis enthusiasts but also a new information processing scheme for intelligent sensing and distinction of different movements,which can offer significant application potential in sports big data collection and the Internet of things.展开更多
文摘BACKGROUND Non-proliferative diabetic retinopathy(NPDR)poses a significant challenge in diabetes management due to its microvascular changes in the retina.Laser photocoagulation,a conventional therapy,aims to mitigate the risk of progressing to proliferative diabetic retinopathy(PDR).AIM To compare the efficacy and safety of multi-spot vs single-spot scanning panretinal laser photocoagulation in NPDR patients.METHODS Forty-nine NPDR patients(86 eyes)treated between September 2020 and July 2022 were included.They were randomly allocated into single-spot(n=23,40 eyes)and multi-spot(n=26,46 eyes)groups.Treatment outcomes,including bestcorrected visual acuity(BCVA),central macular thickness(CMT),and mean threshold sensitivity,were assessed at predetermined intervals over 12 months.Adverse reactions were also recorded.RESULTS Energy levels did not significantly differ between groups(P>0.05),but the multi-spot group exhibited lower energy density(P<0.05).BCVA and CMT improvements were noted in the multi-spot group at one-month posttreatment(P<0.05).Adverse reaction incidence was similar between groups(P>0.05).CONCLUSION While energy intensity and safety were comparable between modalities,multi-spot scanning demonstrated lower energy density and showed superior short-term improvements in BCVA and CMT for NPDR patients,with reduced laser-induced damage.
基金funded by the National Natural Science Foundation of China [Grant No. 12002178]opening project of the State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology) [Grant No. KFJJ22-17M]the Fundamental Research Funds for Central Universities
文摘The detonation wave-aiming warhead can effectively enhance the lethality efficiency. In the past, rules for casing rupture and velocity distribution under asymmetrical initiations were not adequately investigated. In this study, X-ray photography and numerical modelling are used to examine the casing expansions under centre point, asymmetrical one-point, and asymmetrical two-point(with central angles of 45° and 90°) initiations. The results indicate that early casing ruptures are caused by local high pressures, induced by the initiation, detonation wave interaction, and Mach wave onset. The fragment shapes are controlled by the impact angle of the detonation wave. The fragment velocity distributions differ under different initiation types, and the end rarefaction waves can affect the velocity distribution.This study can serve as a reference for the design and optimization of high-efficiency warheads.
基金financially supported by the National Key Research and Development Program of China (Grant No.2022YFE010700)the National Natural Science Foundation of China (Grant No.52171259)+1 种基金the High-Tech Ship Research Project of Ministry of Industry and Information Technology (Grant No.[2021]342)Foundation of State Key Laboratory of Ocean Engineering in Shanghai Jiao Tong University (Grant No.GKZD010086-2)。
文摘During ship operations,frequent heave movements can pose significant challenges to the overall safety of the ship and completion of cargo loading.The existing heave compensation systems suffer from issues such as dead zones and control system time lags,which necessitate the development of reasonable prediction models for ship heave movements.In this paper,a novel model based on a time graph convolutional neural network algorithm and particle swarm optimization algorithm(PSO-TGCN)is proposed for the first time to predict the multipoint heave movements of ships under different sea conditions.To enhance the dataset's suitability for training and reduce interference,various filter algorithms are employed to optimize the dataset.The training process utilizes simulated heave data under different sea conditions and measured heave data from multiple points.The results show that the PSO-TGCN model predicts the ship swaying motion in different sea states after 2 s with 84.7%accuracy,while predicting the swaying motion in three different positions.By performing a comparative study,it was also found that the present method achieves better performance that other popular methods.This model can provide technical support for intelligent ship control,improve the control accuracy of intelligent ships,and promote the development of intelligent ships.
文摘In this paper, a general family of derivative-free n + 1-point iterative methods using n + 1 evaluations of the function and a general family of n-point iterative methods using n evaluations of the function and only one evaluation of its derivative are constructed by the inverse interpolation with the memory on the previous step for solving the simple root of a nonlinear equation. The order and order of convergence of them are proved respectively. Finally, the proposed methods and the basins of attraction are demonstrated by the numerical examples.
基金Project(2015M580491)supported by the China Postdoctoral Science FoundationProject(51404262)supported by the National Natural Science Foundation of China+1 种基金Project(2014XT01)supported by the Research Funds for the Central Universities,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘The purpose of this work was to explore the influence law of vibration load on rock mass structure and slope stability.Based on the type and transmission way of vibration stress wave,the main stress in the horizontal and vertical directions was analyzed and the superposition effect of the stress wave was revealed.After the mechanical analysis of the sliding mass,the calculation formulas of the anti-sliding force and the sliding force were derived and the damage mechanism of blasting vibration to the structural plane was defined.In addition,according to the structure and lithologic parameter of the slope as well as the vibration monitoring data,the west slope stability of Xiaolongtan open pit mine was analyzed.The results show that the time-dependent stability factor is proportional to the vibration speed and the peak values appear at the same time.Vibration load promotes the breakage of the structural plane leading to the drop of the west slope stability factor by 0.23%.Under the multipoint simultaneous blasting,the fluctuating laws of the stability factors are consistent.The more the start-up points are,the higher the weakening degree to the slope stability is.Under the multipoint allochronic blasting,the stability factor depends on the synthetic waveform structure of all vibration waves.The greater the blasting time difference is,the lower the weakening degree to the slope stability is.Selecting the reasonable quantity of start-up points and time difference could fully reduce the adverse influence of vibration load to slope stability.
基金This project is supported by Doctoral Fundation of China(No.20010487002) and Municipal Key Technology R&D Program of Guangzhou, China(No, 2002Z3-0211).
文摘The study of multipoint blank holder force（BHF） control is carried out for hydroforming a complicated shape motorcycle fuel tank. By finite element method （FEM） simulation, the configuration of multipoint blank holder cylinders and the setting of local BHF are optimized, and the influences of the multipoint BHF on the hydromechanical deep drawing and conventional hydroforming processes are studied. The desired fluid pressure and whole BHF are predicted for hydromechanical deep drawing process. Finally, simulation results are testified by forming experiment, and they are in agreement very well.
基金supported by the National Natural Science Foundation of China(Nos.11475131,11975307,and 11575184)the National Magnetic Confinement Fusion Energy Development Research(No.2013GB104003)。
文摘The neutron flux monitor(NFM)system is an important diagnostic subsystem introduced by large nuclear fusion devices such as international thermonuclear experimental reactor(ITER),Japan torus-60,tokamak fusion test reactor,and HL-2 A.Neutron fluxes can provide real-time parameters for nuclear fusion,including neutron source intensity and fusion power.Corresponding to different nuclear reaction periods,neutron fluxes span over seven decades,thereby requiring electronic devices to operate in counting and Campbelling modes simultaneously.Therefore,it is crucial to design a real-time NFM system to encompass such a wide dynamic range.In this study,a high-precision NFM system with a wide measurement range of neutron flux is implemented using realtime multipoint linear calibration.It can automatically switch between counting and Campbelling modes with variations in the neutron flux.We established a testing platform to verify the feasibility of the NFM system,which can output the simulated neutron signal using an arbitrary waveform generator.Meanwhile,the accurate calibration interval of the Campbelling mode is defined well.Based on the above-mentioned design,the system satisfies the requirements,offering a dynamic range of 10~8 cps,temporal resolution of 1 ms,and maximal relative error of 4%measured at the signal-to-noise ratio of 15.8 dB.Additionally,the NFM system is verified in a field experiment involving HL-2 A,and the measured neutron flux is consistent with the results.
文摘We describe a system for multipoint videoconferencing that offers extremely low end-to-end delay, low cost and complexity, and high scalability, alongside standard features associated with high-end solutions such as rate matching and per- sonal video layout. The system accommodates heterogeneous receivers and networks based on the Internet Protocol and relies on scalable video coding to provide a coded representation of a source video signal at multiple temporal and spatial resolutions as well as quality levels. These are represented by distinct bitstream components which are created at each end-user encoder. Depending on the specific conferencing environment, some or all of these components are transmitted to a Scalable Video Conferencing Server (SVCS). The SVCS redirects these components to one or more recipients depending on, e.g., the available network con- ditions and user preferences. The scalable aspect of the video coding technique allows the system to adapt to different network conditions, and also accommodates different end-user requirements (e.g., a user may elect to view another user at a high or low spatial resolution). Performance results concerning flexibility, video quality and delay of the system are presented using the Joint Scalable Video Model (JSVM) of the forthcoming SVC (H.264 Annex G) standard, demonstrating that scalable coding outper- forms existing state-of-the-art systems and offers the right platform for building next-generation multipoint videoconferencing systems.
基金supported by the Energy Efficiency and Resources Program of the Korea Institute of Energy Technology Evaluation andPlanning(KETEP,Grant No.20132510100060)the Basic Research Program of Korea Institute of Geoscience and Mineral Resources(KIGAM,GP2017-024)+2 种基金funded by the Ministry of ScienceICTFuture Planning of Korea
文摘The static modeling and dynamic simulation are essential and critical processes in petroleum exploration and development. In this study, lithofacies models for Wabiskaw Member in Athabasca, Canada are generated by multipoint statistics(MPS) and then compared with the models built by sequential indicator simulation(SIS). Three training images(Tls) are selected from modern depositional environments;the Orinoco River Delta estuary, Cobequid bay-Salmon River estuary, and Danube River delta environment. In order to validate lithofacies models, average and variance of similarity in lithofacies are calculated through random and zonal blind-well tests.In random six-blind-well test, similarity average of MPS models is higher than that of SIS model. The Salmon MPS model closely resembles facies pattern of Wabiskaw Member in subsurface. Zonal blind-well tests show that successful lithofacies modeling for transitional depositional setting requires additional or proper zonation information on horizontal variation, vertical proportion, and secondary data.As Wabiskaw Member is frontier oilsands lease, it is impossible to evaluate the economics from production data or dynamic simulation. In this study, a dynamic steam assisted gravity drainage(SAGD)performance indicator(SPIDER) on the basis of reservoir characteristics is calculated to build 3 D reservoir model for the evaluation of the SAGD feasibility in Wabiskaw Member. SPIDER depends on reservoir properties, economic limit of steam-oil ratio, and bitumen price. Reservoir properties like porosity,permeability, and water saturation are measured from 13 cores and calculated from 201 well-logs. Three dimensional volumes of reservoir properties are constructed mostly based on relationships among properties. Finally, net present value(NPV) volume can be built by equation relating NPV and SPIDER. The economic area exceeding criterion of US$ 10,000 is identified, and the ranges of reservoir properties are estimated. NPV-volume-generation workflow from reservoir parameter to static model provides costand time-effective method to evaluate the oilsands SAGD project.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11674397 and 61671455
文摘Measurement-device-independent quantum key distribution(MDI-QKD) offers a practical way to realize a startype quantum network. Previous experiments on MDI-QKD networks can only support the point-to-point communication. We experimentally demonstrate a plug-and-play MDI-QKD network which can support the pointto-multipoint communication among three users. Benefiting from the plug-and-play MDI-QKD architecture,the whole network is automatically stabilized in spectrum, polarization, arrival time, and phase reference. The users only need the encoding devices, which means that the hardware requirements are greatly reduced. Our experiment shows that it is feasible to establish a point-to-multipoint MDI-QKD network.
文摘A compact, low cost, multipoint Thomson scattering diagnostic system for HT-7 superconducting tokamak has been in operation since 1999. Its capability of measuring electron temperatures is in the range of 200 eV to 2 keV at a density of a few times IO12 cm-3, with a spatial resolution of 2.4 cm for 5 spatial points and a temporal resolution of 1 ms-1 s for 8 time points. The main components of the diagnostic system include a 20-25 J Nd: glass laser with 35 ns pulse width (8 pulses per burst), a KDP frequency-doubling unit, spherical mirrors of multipass input optical system, a wide-angle collection objective, a bandpass glass filter for reducing the stray light to zero a f/2.5 polychromator, a fiberglass collimator, a photomultiplier's box with electronic preamplifier, high gain and high signal/noise ratio, CAMAC data acquisition and so on. The multipass optical system has been successful at increasing the quantity of scattered photons by passing the probing laser beam 10 times through the plasma under investigation. The HT7 Thomson scattering diagnostic has provided successfully the information on two-dimensional electron temperature in the plasma of HT-7 tokamak with LHCD and IBW.
文摘The multipoint steam injection string of the horizontal well is a commonly used downhole component for high efficiency steam injection of the thermal recovery horizontal well. A reasonable layout of the valves to ensure an even steam output of each point is still not well designed. At present, a general design method which is urgently necessary isn＇ t applied by each factory. According to the balance relationship of the momentum, the energy and the mass of the fluid flowing in the string, the pressure distribution equation of the fluid flowing in the multipoint steam injection string is built. On the basis of this equation, the design calculation method of the multipoint steam injection string is come up with. A specific example is given in the paper. Study shows that, with the equation built in this paper, the string can be designed with each axial valve having the same output, so that the technical demand of an even steam injection of the horizontal well section can be met.
基金Funded by the International S&T Cooperation Program of China(No. 2011DFA72120)the Program for Innovation Research Team in University of Shanxi Province(No.2011018022)the University Young and Middle-aged Top-notch Innovative Talent Program of Shanxi Province(No.20091020235)
文摘A multipoint excitation experiment system of the 1Cr18Ni9 steel plate-pipe network as the main vibration body was established,which used transient flow produced by the wave exciter to excite the 1Cr18Ni9 steel plate-pipe network to vibrate.The experimental results show that the 1Cr18Ni9 steel plate vibrates in three dimensions.The vibrations of the particles of the steel plate distributing along the pipe＇s axial have phase differences and take place near the cylinder side first.Therefore,it is a multipoint vibration mode.The amplitude of the 1Cr18Ni9 steel plate increases as the system pressure increases and decreases as the wave exciter＇s frequency decreases.The vibration intensity of the particles of the 1Cr18Ni9 steel plate close to the cylinder is the strongest and the amplitude is the highest in Y direction at a given system frequency.The vibration intensity of the particles close to the wave exciter is the strongest and the amplitude is the smallest in Z direction at a given system pressure.
文摘In order to improve the power of initiating explosive warheads, besides exploring new type of high explosive, multipoint initiation technology becomes the research focus. With research on electronic safety and arming devices （ESADs）, pulse power devices and slapper detonators, a hardware control circuit was designed for multipoint initiation control system based on complex programmable logic device （ CPLD ）. In addition, a real-time monitoring interface based on virtual instru- ments technology was designed by the prevailing software of Laboratory Virtual Instrument Engineer- ing Workbench （LabVIEW）. It provides users a real-time status of the hardware circuit system. Mo- reover, a series of experiments were done on the software and hardware platform. The results show that the signals transmission, collection, analysis and display can be realized reliably through a serial port line. It is verified that using a serial bus controller for multiple initiators is reasonable. Successful design of the platform will play an important foundation for the theory and engineering of the fu- ture weapon system. Surely, it will become one of the development directions for intelligent initia- tion system.
文摘A collocation method with multipoint weighting is presented in this paper.Itconverges as rapidly as the Galerkin method hut needs less computation effort.By means ofthe technique with Gauss points(superconvergence points)as the collocating points,dipole anddipole array are analyzed,and the numerical results are in good agreement with those given inrelative references.
文摘Given a regular compact set E in , a unit measure μ supported by , a triangular point set , and a function f , holomorphic on E , let πβ,fn,m be the associated multipoint β-Padé approximant of order (n,m) . We show that if the sequence πβ,fn,m , n∈Λ , ∧∈n,k are uniformly distributed on with respect to u as n∈Λ . Furthermore, a result about the behavior of the zeros of the exact maximally convergent sequence Λ is provided, under the condition that Λ is “dense enough”.
文摘The VC merging algorithm is used widely for multipoint to point ATM communication. For AAL5 lacking multiplex ID field, the downstream receiving point cannot distinguish the multiplexed source in a multipoint to point VC after VC merging. So the source based rate distribution algorithms cannot work properly. We designed a source detection algorithm to enable the switch to know the number of sources and the cell rate of each source in a multipoint to point VC. These information is very important for the source based rate distribution algorithm. We used the ERICA algorithm in our simulations and the simulations demonstrated the proper operation of the source detection algorithm.
基金National Natural Science Foundations of China(Nos.61505035,81470661,11604057)Science and Technology Project of Guangdong Province,China(No.2016A010101024)
文摘Based on massive MIMO （ multiple-input multiple-output） （M2M） systems, in order to avoid pilot contamination and improve the performance of rapacity, a pilot training transmission scheme was designed for pilot decontamination by utilizing orthogonal mbearriers of OFDM （ orthogonal frequency division multiplexing） during pilot transmission phase and a joint optimized transceiver design for multi-antenna user pairs was proposed during the data transmission phase. The massive M2M system included a single relay station, multiple paired source nodes and destination nodes. Source nodes precoding matrices and relay station precoding matrix were jointly optimized by maximizing the weighted sum-rate in OFDM systems. After some mathematical manipulation to sum-rate, the cost function of sum.rate was expressed as quadratic optimizing expressions which could be solved by regular convex optlmiTation softwares. Different from existing algorithms, the proposed precoding design was based on massive MIMO OFDM systems with multi-antenna users pairs together pilot decontamination transmission arrangement. Simulations indicate the effectiveness of the proposed optimal precoding system. The proposed scheme not only can reduce pilot contamination, but also can improve performance of bit-error-rate （BER） as wed as sum- rate contrast to existing algorithms. In addition, it shows that the proposed M2M massive MIMO system works steadily when the number of users increases in large scale.
基金supported by the National Key R&D Program of China(Grant No.2019YFE0120300)the National Natural Science Foundation of China(Grant Nos.62171414,52175554,52205608,62001431)+1 种基金the Fundamental Research Program of Shanxi Province(Grant Nos.20210302123059,20210302124610)Program for the Innovative Talents of Higher Education Institutions of Shanxi。
文摘Technology-assisted ball training systems have become a research hotspot due to their ability to provide quantitative data for guiding athletes to address their areas of improvement.However,traditional tennis training systems still have some limitations;for instance,they are subjective,expensive,heavy,and time-consuming.In this research,an assistant training tennis racket,which consists of arrayed flexible sensors and an inertial measurement unit,has been proposed to comprehensively analyze the representative actions’force and acceleration.Consisting of MXene as the sensitive material and melamine sponge as the substrate(named MMSS),the flexible sensor exhibited an excellent sensitivity of 5.35 kPa^(-1)(1.1-22.2 kPa)due to the formation of a 3D conductive network.Moreover,the sensor retained a high sensitivity of 0.6 k Pa-1in an ultrawide measurement range(22.2-266 kPa).In addition to recognizing the type of hitting action,an artificial intelligence algorithm was introduced to accurately differentiate the five typical motion behaviors with an accuracy rate of 98.2%.This study not only proposes a comprehensive assistant training tennis racket for improving the techniques of tennis enthusiasts but also a new information processing scheme for intelligent sensing and distinction of different movements,which can offer significant application potential in sports big data collection and the Internet of things.
