A predictive model for regional zenith tropospheric delay correction

The conventional zenith tropospheric delay(ZTD)model(known as the Saastamoinen model)does not consider seasonal variations affecting the delay,giving it low accuracy and stability.This may be improved with adjustments to account for annual and semi-annual variations.This method uses ZTD data provided by the Global Geodetic Observing System to analyze seasonal variations in the bias of the Saastamoinen model in Asia,and then constructs a model with seasonal variation corrections,denoted as SSA.To overcome the dependence of the model on in-situ meteorological parameters,the SSA+GPT3 model is formed by combining the SSA and GPT3(global pressure-temperature)models.The results show that the introduction of annual and semi-annual variations can substantially improve the Saastamoinen model,yielding small and time-stable variations in bias and root mean square(RMS).In summer and autumn,the bias and RMS are noticeably smaller than those from the Saastamoinen model.In addition,the SSA model performs better in low-latitude and low-altitude areas,and bias and RMS decease with the increase of latitude or altitude.The prediction accuracy of the SSA model is also evaluated for external consistency.The results show that the accuracy of the SSA model(bias:-0.38 cm,RMS:4.43 cm)is better than that of the Saastamoinen model(bias:1.45 cm,RMS:5.16 cm).The proposed method has strong applicability and can therefore be used for predictive ZTD correction across Asia.

Multifunctional mixed analog/digital signal processor based on integrated photonics

Photonic signal processing offers a versatile and promising toolkit for contemporary scenarios ranging from digital optical communication to analog microwave operation.Compared to its electronic counterpart,it eliminates inherent bandwidth limitations and meanwhile exhibits the potential to provide unparalleled scalability and flexibility,particularly through integrated photonics.However,by far the on-chip solutions for optical signal processing are often tailored to specific tasks,which lacks versatility across diverse applications.Here,we propose a streamlined chip-level signal processing architecture that integrates different active and passive building blocks in silicon-on-insulator(SOI)platform with a compact and efficient manner.Comprehensive and in-depth analyses for the architecture are conducted at levels of device,system,and application.Accompanied by appropriate configuring schemes,the photonic circuitry supports loading and processing both analog and digital signals simultaneously.Three distinct tasks are facilitated with one single chip across several mainstream fields,spanning optical computing,microwave photonics,and optical communications.Notably,it has demonstrated competitive performance in functions like image processing,spectrum filtering,and electro-optical bandwidth equalization.Boasting high universality and a compact form factor,the proposed architecture is poised to be instrumental for next-generation functional fusion systems.

Thickness effect on solar-blind photoelectric properties of ultrathinβ-Ga_(2)O_(3)films prepared by atomic layer deposition

Theβ-Ga_(2)O_(3)films with different thicknesses are prepared by an atomic layer deposition system.The influence of film thickness on the crystal quality is obvious,indicating that the thicker films perform better crystal quality,which is verified from x-ray diffraction(XRD)and scanning electron microscope(SEM)results.The Ga_(2)O_(3)-based solar blind photodetectors with different thicknesses are fabricated and studied.The experimental results show that the responsivity of the photodetectors increases exponentially with the increase of the film thickness.The photodetectors with inter-fingered structure based on 900 growth cyclesβ-Ga_(2)O_(3)active layers(corresponding film thickness of 58 nm)exhibit the best performances including a low dark current of 134 fA,photo-to-dark current ratio of 1.5×10^(7),photoresponsivity of 1.56 A/W,detectivity of 2.77×10^(14)Jones,and external quantum efficiency of 764.49%at a bias voltage of 10 V under 254-nm DUV illumination.The photoresponse rejection ratio(R_(254)/R_(365))is up to 1.86×10^(5).In addition,we find that the photoelectric characteristics also depend on the finger spacing of the MSM structure.As the finger spacing decreases from 50μm to10μW,the photoresponsivity,detectivity,and external quantum efficiency increase significantly.

Path Computing Scheme with Low-Latency and Low-Power in Hybrid Cloud-Fog Network for IIoT

With the rapid development of the Industrial Internet of Things(IIoT),the traditional centralized cloud processing model has encountered the challenges of high communication latency and high energy consumption in handling industrial big data tasks.This paper aims to propose a low-latency and lowenergy path computing scheme for the above problems.This scheme is based on the cloud-fog network architecture.The computing resources of fog network devices in the fog computing layer are used to complete task processing step by step during the data interaction from industrial field devices to the cloud center.A collaborative scheduling strategy based on the particle diversity discrete binary particle swarm optimization(PDBPSO)algorithm is proposed to deploy manufacturing tasks to the fog computing layer reasonably.The task in the form of a directed acyclic graph(DAG)is mapped to a factory fog network in the form of an undirected graph(UG)to find the appropriate computing path for the task,significantly reducing the task processing latency under energy consumption constraints.Simulation experiments show that this scheme’s latency performance outperforms the strategy that tasks are wholly offloaded to the cloud and the strategy that tasks are entirely offloaded to the edge equipment.

Transverse manipulation of particles using Bessel beam of tunable size generated by cross-phase modulation

We report on a method to achieve multiple microscopic particles being trapped and manipulated transversely by using a size-tunable Bessel beam generated by cross-phase modulation(XPM)based on the thermal nonlinear optical effect.The results demonstrate that multiple polystyrene particles can be stably trapped simultaneously,and the number of the trapped particles can be controlled by varying the trapping beam power.In addition,the trapped particles can be manipulated laterally with micron-level precision by changing the size of J_(0)Bessel beam.This work provides a simple but efficient way to trap and manipulate multiple particles simultaneously,which would have potential applications in many fields such as cell sorting and transportation.

Preparation of Sn-doped Ga_(2)O_(3) thin films and their solar-blind photoelectric detection performance

Sn doping is an effective way to improve the response rate of Ga_(2)O_(3) film based solar-blind detectors. In this paper,Sn-doped Ga_(2)O_(3) films were prepared on a sapphire substrate by radio frequency magnetron sputtering. The films were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet visible spectroscopy, and the effect of annealing atmosphere on the properties of films was studied. The Ga_(2)O_(3) films changed from amorphous to β-Ga_(2)O_(3) after annealing at 900 °C. The films were composed of micro crystalline particles with a diameter of about 5–20 nm.The β-Ga_(2)O_(3) had high transmittance for wavelengths above 300 nm, and obvious absorption for solar-blind signals at 200–280 nm.The metal semiconductor metal type solar-blind detectors were prepared. The detector based on Sn-doped β-Ga_(2)O_(3) thin film annealed in N_2 has the best response performance to 254 nm light. The photo-current is 10 μA at 20 V, the dark-current is 5.76 pA,the photo dark current ratio is 1.7 × 10~6, the response rate is 12.47 A/W, the external quantum efficiency is 6.09 × 10~3%, the specific detection rate is 2.61 × 10~(12) Jones, the response time and recovery time are 378 and 90 ms, respectively.

Privacy Data Management Mechanism Based on Blockchain and Federated Learning

Due to the extensive use of various intelligent terminals and the popularity of network social tools,a large amount of data in the field of medical emerged.How to manage these massive data safely and reliably has become an important challenge for the medical network community.This paper proposes a data management framework of medical network community based on Consortium Blockchain(CB)and Federated learning(FL),which realizes the data security sharing between medical institutions and research institutions.Under this framework,the data security sharing mechanism of medical network community based on smart contract and the data privacy protection mechanism based on FL and alliance chain are designed to ensure the security of data and the privacy of important data in medical network community,respectively.An intelligent contract system based on Keyed-Homomorphic Public Key(KH-PKE)Encryption scheme is designed,so that medical data can be saved in the CB in the form of ciphertext,and the automatic sharing of data is realized.Zero knowledge mechanism is used to ensure the correctness of shared data.Moreover,the zero-knowledge mechanism introduces the dynamic group signature mechanism of chosen ciphertext attack(CCA)anonymity,which makes the scheme more efficient in computing and communication cost.In the end of this paper,the performance of the scheme is analyzed fromboth asymptotic and practical aspects.Through experimental comparative analysis,the scheme proposed in this paper is more effective and feasible.

HRM: H-tree based reconfiguration mechanism in reconfigurable homogeneous PE array

In order to accommodate the variety of algorithms with different performance in specific application and improve power efficiency,reconfigurable architecture has become an effective methodology in academia and industry.However,existing architectures suffer from performance bottleneck due to slow updating of contexts and inadequate flexibility.This paper presents an H-tree based reconfiguration mechanism(HRM)with Huffman-coding-like and mask addressing method in a homogeneous processing element(PE)array,which supports both programmable and data-driven modes.The proposed HRM can transfer reconfiguration instructions/contexts to a particular PE or associated PEs simultaneously in one clock cycle in unicast,multicast and broadcast mode,and shut down the unnecessary PE/PEs according to the current configuration.To verify the correctness and efficiency,we implement it in RTL synthesis and FPGA prototype.Compared to prior works,the experiment results show that the HRM has improved the work frequency by an average of 23.4%,increased the updating speed by 2×,and reduced the area by 36.9%;HRM can also power off the unnecessary PEs which reduced 51%of dynamic power dissipation in certain application configuration.Furthermore,in the data-driven mode,the system frequency can reach 214 MHz,which is 1.68×higher compared with the programmable mode.

Robust Artificial Noise-Aided Beamforming for A Secure MISO-NOMA Visible Light Communication System

Visible light communication(VLC)and non-orthogonal multiple access(NOMA)have been deemed two promising techniques in the next wireless communication networks.In this paper,secure communications in the presence of potential eavesdropper are investigated for a multiple-input single-output VLC system with NOMA.The artificial noise jamming and beamforming technologies are applied to improve secure performance.A robust resource allocation scheme is proposed to minimize the total transmit power taking into account the constraints on the quality of service requirement of the desired users and the maximum tolerable data rate of the eavesdropper,and the practical imperfect channel state information of both the desired users and the eavesdropper.The formulated non-convex optimization problem is tackled based onS-Procedure and semi-definite programming relaxation.Simulation results illustrate that our proposed resource allocation scheme can effectively guarantee communication security and achieve transmit power saving.Moreover,the height and number of LED can significantly affect system performance and the optimum LED height can be obtained for different LED numbers.

Design of broadband achromatic metasurface device based on phase-change material Ge_(2)Sb_(2)Te_(5)

Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.

Electronic structure and optical properties of Ge-and F-doped α-Ga2O3:First-principles investigations

The prospect ofα-Ga2O3 in optical and electrical devices application is fascinating.In order to obtain better performance,Ge and F elements with similar electronegativity and atomic size are selected as dopants.Based on density functional theory(DFT),we systematically research the electronic structure and optical properties of dopedα-Ga2O3 by GGA+U calculation method.The results show that Ge atoms and F atoms are effective n-type dopants.For Ge-dopedα-Ga2O3,it is probably obtained under O-poor conditions.However,for F-dopedα-Ga2O3,it is probably obtained under O-rich conditions.The doping system of F element is more stable due to the lower formation energy.In this investigation,it is found that two kinds of doping can reduce theα-Ga2O3 band gap and improve the conductivity.What is more,it is observed that the absorption edge after doping has a blue shift and causes certain absorption effect on the visible region.Through the whole scale of comparison,Ge doping is more suitable for the application of transmittance materials,yet F doping is more appropriate for the application of deep ultraviolet devices.We expect that our research can provide guidance and reference for preparation ofα-Ga2O3 thin films and photoelectric devices.

Neural-mechanism-driven image block encryption algorithm incorporating a hyperchaotic system and cloud model

An image encryption algorithm is proposed in this paper based on a new four-dimensional hyperchaotic system,a neural mechanism,a Galois field and an improved Feistel block structure,which improves the efficiency and enhances the security of the encryption algorithm.Firstly,a four-dimensional hyperchaotic system with a large key space and chaotic dynamics performance is proposed and combined with a cloud model,in which a more complex and random sequence is constructed as the key stream,and the problem of chaotic periodicity is solved.Then,the key stream is combined with the neural mechanism,Galois field and improved Feistel block structure to scramble and diffuse the image encryption.Finally,the experimental results and security analysis show that the encryption algorithm has a good encryption effect and high encryption efficiency,is secure,and can meet the requirements of practical applications.

Synthesis of flower-like WS_(2) by chemical vapor deposition

Flower-like tungsten disulfide(WS_(2))with a diameter of 5-10μm is prepared by chemical vapor deposition(CVD).Scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),Raman spectroscopy,and ultraviolet-visible(UV-vis)spectroscopy are used to characterize its morphological and optical properties,and its growth mechanism is discussed.The key factors for the formation of flower-like WS_(2)are determined.Firstly,the cooling process causes the generation of nucleation dislocations,and then the"leaf"growth of flower-like WS_(2)is achieved by increasing the temperature.

Bolzano and Phenomenology

Bolzano’s invention of“pure logic”in his Theory of Science laid the foundation for Husserl’s establishment of phenomenology,because Husserl also established a“guidance of pure logic”in Logical Investigations.However,in Husserl’s opinion,“pure logic”is only a necessary thing before the establishment of phenomenology;it is not the last thing in human thought,as well as it is not a core idea of“pure consciousness”.Therefore,Bolzano’s logical concept only promoted Husserl to a“primary phenomenology”,which was only the preparation and entrance of this phenomenological philosophy.

Flexible double-wall carbon foam/Cu-Co oxides based symmetric supercapacitor with ultrahigh energy density

Electrochemical supercapacitors are regarded as a promising electrochemical energy storage device,because of its fast chargeability,long cycle life,and high power density.The connection of porous carbon and extensive electroactive substances have significantly improved their performance.However,the unsuitable constructing strategy and unclear electrochemical mechanism lead to a mismatch between the fast double-layer effect and the sluggish Faradaic behavior at the electrode,degrading the energy density and capacitance performances.Herein,the construction strategy based on the double-wall carbon foam,carbon nanotubes and copper nanocubes provides enhanced electronic structure and ion transport path,resulting in accelerated proton transport and redox insertion/deinsertion processes,as well as surprising electrochemical behaviors of Cu-Co oxide on both positive and negative electrodes(927.9 and 427.0 F g^(−1)at 1 A g^(−1)).A flexible symmetric supercapacitor assembled with the SCF/CNT@Cu/Cu-Co-O delivers a extremely excellent performance.At 1 A g^(−1),the specific capacitance is 337.8 F g^(−1),the energy density hits 60 Wh kg^(−1)at the power density of 17.8 kW kg^(−1).At 10 A g^(−1),the energy density is up to 120.1 Wh kg^(−1),representing the top energy density of supercapacitors.Combining systematical structural optimization and mechanism study,this work broadens the fabricating strategy of hierarchical nanostructures and high-performance electrode materials for energy storage.

Progress in modeling and control of probe-and-drogue autonomous aerial refueling

By refueling aircraft while they are in flight,aerial refueling is an efficient technique to extend their endurance and range.Autonomous Aerial Refueling(AAR)is anticipated to be used to complete aerial refueling for unmanned aircraft.There are three aerial refueling methods:the Probe-and-Drogue Refueling(PDR)refueling method,the flying-boom refueling method,and the boom-drogue-adapter refueling method.The paper considers the PDR approach,the most challenging of the three,because the flexible hose-drogue assembly has fast dynamics and is susceptible to various kinds of winds,which makes the probe docking with the drogue difficult.PDR is divided into four phases,namely the rendezvous phase,joining phase,refueling phase,and reform phase,with the refueling phase being the most crucial.The controller design faces the greatest challenge during the docking control of the refueling phase since it calls for a high level of safety,precision,and efficiency.As a result,the modeling and control issues encountered during the refueling phase are typical and difficult.The fundamental idea of AAR is presented in the paper first,after which the characteristics and requirements of AAR are outlined.The progress in modeling and control techniques for the AAR’s refueling phase is then systematically reviewed.Finally,potential future work for high safety,precision,and efficiency requirements is examined and suggested.

Security enhancement of artificial neural network using physically transient form of heterogeneous memristors with tunable resistive switching behaviors

As a critical command center in organisms,the brain can execute multiple intelligent interactions through neural networks,including memory,learning and cognition.Recently,memristive-based neuromorphic devices have been widely developed as promising technologies to build artificial synapses and neurons for neural networks.However,multiple information interactions in artificial intelligence devices potentially pose threats to information security.Herein,a transient form of heterogeneous memristor with a stacked structure of Ag/MgO/SiN_(x)/W is proposed,in which both the reconfigurable resistive switching behavior and volatile threshold switching characteristics could be realized by adjusting the thickness of the SiN_(x)layer.The underlying resistive switching mechanism of the device was elucidated in terms of filamentary and interfacial effects.Representative neural functions,including short-term plasticity(STP),the transformation from STP to long-term plasticity,and integrate-and-fire neuron functions,have been successfully emulated in memristive devices.Moreover,the dissolution kinetics associated with underlying transient behaviors were explored,and the water-assisted transfer printing technique was exploited to build transient neuromorphic device arrays on the water-dissolvable poly(vinyl alcohol)substrate,which were able to formless disappear in deionized water after 10-s dissolution at room temperature.This transient form of memristive-based neuromorphic device provides an important step toward information security reinforcement for artificial neural network applications.

Aerial refueling scheduling of multi-receiver and multi-tanker under spatial-temporal constraints for forest firefighting

Forest fires pose a significant threat to human life and property,so the utilization of unmanned aircraft systems provides new ways for forest firefighting.Given the constrained load capacities of these aircraft,aerial refueling becomes crucial to extend their operational time and range.In order to address the complexities of firefighting missions involving multi-receiver and multi-tanker deployed from various airports,first,a fuel consumption calculation model for aerial refueling scheduling is established based on the receiver path.Then,two distinct methods,including an integrated one and a decomposed one,are designed to address the challenges of establishing refueling airspace and allocating tasks for tankers.Both methods aim to optimize total fuel consumption of the receivers and tankers within the aerial refueling scheduling framework.The optimization problem is established as nonlinear optimization models along with restrictions.The integrated method seamlessly combines refueling rendezvous point scheduling and tanker task allocation into unified process.It has a complete solution space and excels in optimizing total fuel consumption.The decomposed method,through the separation of rendezvous point scheduling and task allocation,achieves a reduced computational complexity.However,this comes at the cost of sacrificing optimality by excluding specific feasible solutions.Finally,numerical simulations are carried out to verify the feasibility and effectiveness of the proposed methods.These simulations yield insights crucial for the practical engineering application of both the integrated and decomposed methods in real-world scenarios.This comprehensive approach aims to enhance the efficiency of forest firefighting operations,mitigating the risks posed by forest fires to human life and property.

Annealing effects on the optical and electrochemical properties of tantalum pentoxide films

Tantalum pentoxide(Ta_(2)O_(5)) has attracted intensive attention due to their excellent physicochemical properties.Ta_(2)O_(5) films were synthesized via electron beam evaporation(EBE)and subsequently annealed at different temperatures ranging from 300 to 900℃.X-ray diffraction(XRD)results show that amorphous Ta_(2)O_(5) thin films form from 300 to 700℃ and then a phase transition to polycrystalline β-Ta_(2)O_(5) films occurs since 900℃.The surface morphology of the Ta_(2)O_(5) films is uniform and smooth.The resulted Ta_(2)O_(5)films exhibit excellent transmittance properties for wavelengths ranging from 300 to 1100 nm.The bandgap of the Ta_(2)O_(5) films is broadened from 4.32 to 4.46 eV by annealing.The 900℃ polycrystalline film electrode has improved electrochemical stability,compared to the other amorphous counterparts.

Review on application of phase change materials in asphalt pavement

Phase change materials(PCMs)can regulate the temperature in asphalt pavement and minimize temperature-related problems,such as rutting and thermal cracking,because of their ability to store and release latent heat.Suitable PCMs can also enable additional road surface functions,such as snow melting ability,freeze-thaw cycle resistance,and heat island reduction.These functions are helpful in achieving intelligent,green,and sustainable transportation systems.Although the research on PCMs for asphalt pavement has been carried out for more than 10 years,a systematic material system and mature application technology have not yet been formed.The main reasons for restricting the development of this technology include the lack of suitability between the PCMs and asphalt pavement,the quantitative characterization of phase change temperature regulation property,and the evaluation of the effect of phase change energy storage on improving pavement performance.Although the published review has made a comprehensive summary of the existing research,it has yet to identify the key restricting the development of this technology and carry out a review and discussion based on it.To grasp the development status of the application of PCMs in asphalt pavement,sort out the development needs and break through the technical barriers,this study systematically summarizes the preparation and performance of PCMs for asphalt pavement,compares the performance and evaluation methods of asphalt mixtures with different PCMs,and summarizes the numerical simulation methods of phase change asphalt mixtures.Finally,this study presents potential approaches to address critical technical issues and discusses possible future research.