Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as ...Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are invasive and relatively expensive. A geoelectric investigation involving vertical electrical sounding was carried in parts of Enugu town, Enugu state, Nigeria. The survey was aimed at extrapolating the result of pumping tests over an area. Using the Dar Zarrouk parameter, a β constant of 0.32 was found to translate resistivity to transmissivity with clay content as the primary factor controlling the hydraulic conductivity. Results of the study show a strong correlation between aquifer transmissivity and longitudinal conductance (R2 = 0.82). Estimation of aquifer transmissivity values based on the results of the resistivity measurements also made it possible to demarcate area with good groundwater potential in parts of Enugu town, Nigeria.展开更多
During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures wit...During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation.The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system.Thus,it is of central importance to analyze the consequences of potential future earthquake(s)on the hydrogeological properties of a repository site for spent nuclear fuel disposal.Based on the detailed site characterization data of the repository site at Forsmark,Sweden,we conduct a three-dimensional(3D)seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code(3DEC).We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution.An earthquake with a magnitude of M_(w)=5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed,with the faulting dynamics controlled by a strength weakening law.We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects.We further diagnose the distribution of fracture hydro-mechanical properties(e.g.mechanical/hydraulic aperture,hydraulic transmissivity)before and after the earthquake in order to quantify earthquakeinduced hydraulic changes in the fracture network.It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault.Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks.展开更多
The application of geophysical methods in combination with pumping tests provides a cost-effective and efficient alternative to estimate aquifer parameters. In this study, nineteen Schlumberger vertical electrical sou...The application of geophysical methods in combination with pumping tests provides a cost-effective and efficient alternative to estimate aquifer parameters. In this study, nineteen Schlumberger vertical electrical soundings (VES) were occupied in parts of Bayelsa State using a maximum current electrode separation ranging beweeen 300 - 400 m with the aim of estimating the transmissivity of the alluvial aquifer in areas where no pumping test has been carried out. Four of the soundings were carried out near existing boreholes in which pumping test had been carried out. The VES data obtained was interpreted, and layer parameters such as true resistivities and thickness were determined. The geoelectric parameters were used to generate the Dar Zarrouk parameters. Correlating the Dar Zarrouk parameter (e.g longitudinal unit conductance) with transmissivity derived from pumping test data, a constant was found which translate longitudinal unit conductance to transmissivity in a hydrogeological setting where effective porosity is the primary control on resistivity and hydraulic conductivity. Transmissivity determined from the pumping test data range between 1634.0 - 5292.0 m2/day while transmissivity values estimated from the longitudinal unit conductance (Lc) range between 721 - 8991 m2/day. The transmissivity estimated from the pumping test (Tp) data and transmissivity estimated from the longitudinal conductance (Lc) on comparison show excellent correlation (R2 = 0.92). The high transmissivity values agree with the geology of the Benin Formation (Coastal Plain sands) consisting of fine-medium-coarse sands. The results give a useful first approximation of the transmissivity and could be used to site exploratory boreholes.展开更多
Global dimming term was introduced in 1990s which means the decline in global radiation. This decline was reported in several studies across the world. In the present study time series analysis of global radiation (19...Global dimming term was introduced in 1990s which means the decline in global radiation. This decline was reported in several studies across the world. In the present study time series analysis of global radiation (1960-2003), transmissivity (1960-2003) and bright sunshine hours (1973-2003) has been done over Nagpur during pre-monsoon (March to May) and monsoon seasons (June-September). A significant decrease in global radiation and transmissivity has been reported for both the seasons and it was higher during pre-monsoon compared to monsoon. Bright sunshine hour has also shown good agreement with the previous trend with a significant trend on pre-monsoon months only. Mann Kendall test was performed to confirm the significance of reported trend.展开更多
This study was undertaken to determine the hydrologic properties of the aquifer materials at Ogbozara-Opi/Ekwegbe-Agu and environs by the estimation of the aquifer transmissivity using Dar Zarrouk parameters. The stud...This study was undertaken to determine the hydrologic properties of the aquifer materials at Ogbozara-Opi/Ekwegbe-Agu and environs by the estimation of the aquifer transmissivity using Dar Zarrouk parameters. The study area lies in the Anambra basin and is underlain, from bottom to top, by 3 prominent geologic formations;Enugu Formation, Mamu Formation and Ajali Formation respectively. A total of 19 sounding stations were occupied within the study area using the Ohmega resistivity meter. The VES data were interpreted using the conventional partial curve matching technique to obtain initial model parameters which were later used as input data for computer iterative modelling using the Interpex software. These analyses were further combined with information from two existing boreholes in the study area to estimate aquifer hydraulic parameters using Dar-Zarrouk parameters. The layer parameters thus obtained revealed that the dominant curve type obtained from the different formations is the AK curve type followed by the HK curve type. An average of 6 geo-electric layers were delineated across all transect taken with resistivity values ranging from 25.42 - 105.85 Ωm, 186.38 - 3383.3 Ωm and 2992.3 - 6286.4 Ωm in the Enugu, Mamu and Ajali Formations respectively. Results of the study revealed the aquifer resistivity in the study area ranges from 1 - 500 Ωm. The depth to the water table range from 13 - 208 m with a mean value of 76.05, while aquifer thickness varies between 95 and 140 m with a mean value of 102.89 m. The values of the Dar-Zarrouk parameters revealed that the transverse resistance varies between −10,000 - 170,000 Ωm<sup>2</sup>, while the longitudinal conductance varies from 0.1 - 1 to 1.9 Ω - 1. Similarly, the hydraulic conductivity in the area ranges from 5 to 50 m/day, while the transmissivity values range from 1000 to 14,000 m<sup>2</sup>/day.展开更多
Forests play an important role in the global carbon cycle and have a potential impact on global climatic change.Monitoring forest biomass is of considerable importance in understanding the hydrological cycle.Because o...Forests play an important role in the global carbon cycle and have a potential impact on global climatic change.Monitoring forest biomass is of considerable importance in understanding the hydrological cycle.Because of the problem of dense forest cover,no reliable method with which to retrieve soil moisture in forest areas from the microwave emission signature has been established.All of these issues relate to the microwave emissivity and transmissivity characteristics of a forest.The microwave emission contribution received by a sensor above a forest canopy comes from both the soil surface and the vegetation layer.To analyze the relationship of forest biomass and forest emission and transmissivity,a high-order emission model,the matrix-doubling model,which consists of both soil and vegetation models,was developed and then validated for a young deciduous forest stand in a field experiment.To simulate the emissivity and transmissivity of a deciduous forest in the L and X bands using the matrix-doubling model,the parameters of components of deciduous trees when the leaf area index varies from 1 to10 were generated by an L-system and a forest growth model.The emissivity and transmissivity of a forest and the relationships of these parameters to forest biomass are presented and analyzed in this paper.Emissivity in the L band when the leaf area index is less than 6 and at viewing angles less than 40°,and transmissivity in the L band are the most sensitive parameters in deciduous forest biomass estimation.展开更多
Forests have invariably been considered as an obstacle in retrieving land surface parameters from spaceborne passive microwave brightness temperature(T_(B))observations.For quantifying the effect of forests on microwa...Forests have invariably been considered as an obstacle in retrieving land surface parameters from spaceborne passive microwave brightness temperature(T_(B))observations.For quantifying the effect of forests on microwave signals,several models have been developed.However,these models rarely reveal the dependence of microwave radiation on forest types,which can hardly meet the needs of high-accuracy retrieval of terrestrial parameters in forested regions.A ground-based microwave radiometric observation experiment was designed to investigate the dependence of microwave radiation on frequency,polarization,and forest type.Downward TB at 18.7-and 36.5-GHz for horizontal-and vertical-polarization from the forest canopy was measured at 14 sample plots in Northeast China,along with snowpack and forest structural parameters.By providing fits to experimental data,new empirical transmissivity models for three forest types were developed,as a function of woody stem volume and depending on the frequency/polarization.The proposed models give diverse asymptotic transmissivity saturation levels and the corresponding saturation point of woody stem volume for different forest types.Root-mean-square error results between T_(B) simulations and Advanced Microwave Scanning Radiometer-2 observations are approximately 3-6 K.This study provides an experimental and theoretical reference for further development of inversion models for snow parameters in forested areas.展开更多
Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization...Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.展开更多
The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
In this paper,we propose a random access scheme termed sign-compute diversity slotted ALOHA(SCDSA).The SCDSA scheme combines diversity transmission with compute-and-forward.Without considering the capture effect and m...In this paper,we propose a random access scheme termed sign-compute diversity slotted ALOHA(SCDSA).The SCDSA scheme combines diversity transmission with compute-and-forward.Without considering the capture effect and multiple user detection techniques,our scheme can reach a high throughput of 0.98 without feedback under finite frame size settings,where the upper bound on performance is 1.Moreover,a lower bound on throughput performance is derived,which is tight in some parameter settings and can be used to approximate theoretical performance.Simulation results validate our analysis and confirm the advantages of our proposed scheme.展开更多
The state-of-the-art optical atomic clocks and the time-frequency signal transmission open a fresh field for gravity potential(geopotential)determination.Various methods,including optical fiber frequency transfer,sate...The state-of-the-art optical atomic clocks and the time-frequency signal transmission open a fresh field for gravity potential(geopotential)determination.Various methods,including optical fiber frequency transfer,satellite two-way,satellite common-view,satellite carrier phase,VLBI,tri-frequency combination,and dual-frequency combination,were developed to determine the geopotential differences using optical atomic clocks and then determine the geopotential at station B based on the geopotential at station A.This review elaborates the principles,methods,scientific objectives,applications,and relevant research trends of geopotential determination based on time-frequency signals.展开更多
Gynandromorphs,rare in vertebrates,exhibit distinct sex-determining gene expression on each side of the body despite sharing a uniform hormonal environment.This provides a unique opportunity to investigate the respect...Gynandromorphs,rare in vertebrates,exhibit distinct sex-determining gene expression on each side of the body despite sharing a uniform hormonal environment.This provides a unique opportunity to investigate the respective roles of genes and hormones in sex determination.We accidently obtained a gynandromorphic Zebra Finch with a male-female chimeric appearance but only with an ovary-like gonad.Its plasma estradiol was significantly higher than that of age-matched females,and its sexual partner preference was also feminine.Although it did not sing like males,its calls showed masculinization.In the brain on one side of the body with male plumage,the area of song motor nucleus,the robust nucleus of the arcopallium(RA),and the excitatory synaptic transmission of RA projection neurons showed masculinization.Transcriptome analysis revealed that genes related to cholinergic neuron function were significantly upregulated in the masculinized side of brain.Moreover,there were extensive and consistent expression differences of neuroactive substance receptor genes in both sides of body,indicating that cell-autonomous determination plays a key role in sex dimorphism of neuromodulation.展开更多
The age-hardening response,mechanical,and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.%scandium(Sc)were compared.Using advanced techniques such as aberration-corrected trans...The age-hardening response,mechanical,and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.%scandium(Sc)were compared.Using advanced techniques such as aberration-corrected transmission electron microscopy and first-principles calculations,the underlying micromechanisms of Sc microalloying were revealed.Results show that the increase in strength of the AA7085-Sc alloy is mainly attributed to the decreased Al grain size and increased number density of both Al_(3)Sc@Al_(3)(Sc,Zr)core−shell nanoparticles and Sc-containingη_(p) and GP−η_(p) nanoprecipitates.Strong strain fields and evident electron transfer from Zr to the neighboring matrix Al atoms exist at the Al_(3)Sc@Al_(3)(Sc,Zr)/Al interface.The Sc doping in GP−η_(p) andη_(p) suppresses the GP−η_(p)→η_(p) transformation.Modified corrosion resistance of the AA7085-Sc alloy compared with AA7085 alloy is associated with the fine grain boundary precipitates ofη_(p)hases and narrow precipitation free zone.The reasons of property changes of AA7085 alloy after Sc microalloying are explored based on the multiscale microstructural characterization.展开更多
The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfa...The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.展开更多
To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hyb...To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process.展开更多
Ultrasound neuromodulation shows promise for treating neurological disorders,but the underlying mechanisms remain unclear.Here,we developed an integrated surface acoustic wave(SAW)ultrasound chip enabling simultaneous...Ultrasound neuromodulation shows promise for treating neurological disorders,but the underlying mechanisms remain unclear.Here,we developed an integrated surface acoustic wave(SAW)ultrasound chip enabling simultaneous electrophysiological recording and Ca^(2+) imaging of cultured hippocampal neurons to investigate neuronal excitability and synaptic transmission during ultrasound stimulation.This study revealed,for the first time,three distinct neuronal response patterns induced by SAW ultrasound:an immediate response showing rapid activation,a delayed response exhibiting facilitation after several minutes,and a non-response maintaining baseline activity.Ultrasound stimulation increased action potential firing,enhanced excitatory postsynaptic currents,and elevated intracellular Ca^(2+) levels.These effects were dependent on extracellular Ca^(2+) influx and primarily dominated by L-type Ca^(2+) channels.Our findings suggest that individual neurons exhibit heterogeneous responses to SAW ultrasound stimulation based on their intracellular Ca^(2+) levels and L-type Ca^(2+) channel activity.This integrated approach provides new insights into the cellular mechanisms of ultrasound neuromodulation while highlighting the potential of SAW technology for precise,cell-type-specific neural control.展开更多
Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolatio...Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolation-absorption simultaneously is proposed for low/wide band frequency vibration control.Based on skeleton mass,articulation friction,and the synergistic action among skeleton,articulation,and muscle/tendon,a vibration suppression model with more biological basic characteristics is derived.The validity of model and method is confirmed,and the static and dynamic analysis of the IKBVS system is carried out to investigate the vibration suppression performance.The quasi-zero stiffness region can be achieved with a smaller initial installation angle,medium rod length,smaller foot stiffness,and slightly lighter isolated mass in a wide displacement interval.The coupling mechanism of vibration isolation-absorption is revealed by parameter analysis.The results indicate that the IKBVS structure has favorite dynamic properties due to adjustable nonlinearity,namely,lower and adjustable resonance and anti-resonance frequency/peak and different levels of vibration suppression effect in high-frequency range are achieved readily.This research provides new insight into application of bio-inspired vibration suppression structures in various engineering systems for better vibration control.展开更多
The Stern-Gerlach(SG)experiment is a fundamental experiment for revealing the existence of“spin”.In this experiment,beams of silver atoms are sent through inhomogeneous magnetic fields to observe their deflection.Th...The Stern-Gerlach(SG)experiment is a fundamental experiment for revealing the existence of“spin”.In this experiment,beams of silver atoms are sent through inhomogeneous magnetic fields to observe their deflection.Thus,the conventional SG experiment can be viewed as a magnetic-type spin effect.In this work,we successfully generalize the SG effect from magnetic-type to electric-type by solving Dirac's equation with a potential barrier,revealing an extraordinary spin effect.Beams of Dirac particles can be regarded as matter waves.Based on Dirac's equation,we obtain the explicit forms of the incident,reflected,and transmitted waves.The electric-type SG effect shows that the reflected and transmitted waves can exhibit notable spatial shifts,which depend on the spin direction and the incident angle of the wave.The electrictype SG effect has potential applications for separating Dirac particles with different spin directions and for estimating the spin direction of Dirac particles.Some discussions related to the interaction between spin and the electric field are also presented.展开更多
Speckle-based optical cryptosystems are promising technologies for information security.However,existing techniques mostly rely on digital decryption,resulting in computational delay and undermining the high-speed adv...Speckle-based optical cryptosystems are promising technologies for information security.However,existing techniques mostly rely on digital decryption,resulting in computational delay and undermining the high-speed advantage of optical encryption.Moreover,conventional neural networks are typically effective only on images from the same distribution as the training datasets,limiting their general applicability.In this paper,we propose an all-optical high-speed decryption scheme for real-time recovery of speckle-encoded ciphertexts.By constructing a physics-informed diffractive neural network that approximates the inverse transmission matrix of the scattering medium,secret images can be directly reconstructed from speckle fields without optoelectronic conversion or post-processing.The network is trained with only 2048 samples from the MNIST dataset.Its transfer learning capability is validated across three out-of-distribution datasets,with decrypted images achieving a Pearson correlation coefficient of 0.82 and a structural similarity index measure of 0.75,demonstrating excellent transfer learning capability.For the first time,to our knowledge,this scheme simultaneously overcomes the bottlenecks of decryption delay and limited network generalizability in conventional speckle-based cryptosystems,achieving real-time image decryption with strong transferability.It provides a new pathway for developing low-power,real-time,and broadly applicable optical encryption systems,demonstrating significant potential for applications in high-speed security optical communications.展开更多
Wireless Sensor Networks(WSNs)have become foundational in numerous real-world applications,ranging from environmental monitoring and industrial automation to healthcare systems and smart city development.As these netw...Wireless Sensor Networks(WSNs)have become foundational in numerous real-world applications,ranging from environmental monitoring and industrial automation to healthcare systems and smart city development.As these networks continue to grow in scale and complexity,the need for energy-efficient,scalable,and robust communication protocols becomes more critical than ever.Metaheuristic algorithms have shown significant promise in addressing these challenges,offering flexible and effective solutions for optimizing WSN performance.Among them,the Grey Wolf Optimizer(GWO)algorithm has attracted growing attention due to its simplicity,fast convergence,and strong global search capabilities.Accordingly,this survey provides an in-depth review of the applications of GWO and its variants for clustering,multi-hop routing,and hybrid cluster-based routing in WSNs.We categorize and analyze the existing GWO-based approaches across these key network optimization tasks,discussing the different problem formulations,decision variables,objective functions,and performance metrics used.In doing so,we examine standard GWO,multi-objective GWO,and hybrid GWO models that incorporate other computational intelligence techniques.Each method is evaluated based on how effectively it addresses the core constraints of WSNs,including energy consumption,communication overhead,and network lifetime.Finally,this survey outlines existing gaps in the literature and proposes potential future research directions aimed at enhancing the effectiveness and real-world applicability of GWO-based techniques for WSN clustering and routing.Our goal is to provide researchers and practitioners with a clear,structured understanding of the current state of GWO in WSNs and inspire further innovation in this evolving field.展开更多
文摘Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are invasive and relatively expensive. A geoelectric investigation involving vertical electrical sounding was carried in parts of Enugu town, Enugu state, Nigeria. The survey was aimed at extrapolating the result of pumping tests over an area. Using the Dar Zarrouk parameter, a β constant of 0.32 was found to translate resistivity to transmissivity with clay content as the primary factor controlling the hydraulic conductivity. Results of the study show a strong correlation between aquifer transmissivity and longitudinal conductance (R2 = 0.82). Estimation of aquifer transmissivity values based on the results of the resistivity measurements also made it possible to demarcate area with good groundwater potential in parts of Enugu town, Nigeria.
文摘During the long service period of a nuclear waste repository in crystalline rock,large earthquake(s)may occur nearby the repository site and coseismically alter the local stress field around pre-existing fractures within the geological formation.The resulting fracture normal/shear displacements may lead to fracture opening and further promote the transport of leaked radionuclides into the groundwater system.Thus,it is of central importance to analyze the consequences of potential future earthquake(s)on the hydrogeological properties of a repository site for spent nuclear fuel disposal.Based on the detailed site characterization data of the repository site at Forsmark,Sweden,we conduct a three-dimensional(3D)seismo-hydro-mechanical simulation using the 3Dimensional Distinct Element Code(3DEC).We explicitly represent a primary seismogenic fault zone and its surrounding secondary fracture network associated with a power-law size scaling and a Fisher orientation distribution.An earthquake with a magnitude of M_(w)=5.6 caused by the reactivation of the primary fault zone is modeled by simulating its transient rupture propagating radially outwards from a predefined hypocenter at a specified rupture speed,with the faulting dynamics controlled by a strength weakening law.We model the coseismic response of the off-fault fracture network subject to both static and dynamic triggering effects.We further diagnose the distribution of fracture hydro-mechanical properties(e.g.mechanical/hydraulic aperture,hydraulic transmissivity)before and after the earthquake in order to quantify earthquakeinduced hydraulic changes in the fracture network.It is found that earthquake-induced fracture transmissivity changes tend to follow a power-law decay with the distance to the earthquake fault.Our simulation results and insights obtained have important implications for the long-term performance assessment of nuclear waste repositories in fractured crystalline rocks.
文摘The application of geophysical methods in combination with pumping tests provides a cost-effective and efficient alternative to estimate aquifer parameters. In this study, nineteen Schlumberger vertical electrical soundings (VES) were occupied in parts of Bayelsa State using a maximum current electrode separation ranging beweeen 300 - 400 m with the aim of estimating the transmissivity of the alluvial aquifer in areas where no pumping test has been carried out. Four of the soundings were carried out near existing boreholes in which pumping test had been carried out. The VES data obtained was interpreted, and layer parameters such as true resistivities and thickness were determined. The geoelectric parameters were used to generate the Dar Zarrouk parameters. Correlating the Dar Zarrouk parameter (e.g longitudinal unit conductance) with transmissivity derived from pumping test data, a constant was found which translate longitudinal unit conductance to transmissivity in a hydrogeological setting where effective porosity is the primary control on resistivity and hydraulic conductivity. Transmissivity determined from the pumping test data range between 1634.0 - 5292.0 m2/day while transmissivity values estimated from the longitudinal unit conductance (Lc) range between 721 - 8991 m2/day. The transmissivity estimated from the pumping test (Tp) data and transmissivity estimated from the longitudinal conductance (Lc) on comparison show excellent correlation (R2 = 0.92). The high transmissivity values agree with the geology of the Benin Formation (Coastal Plain sands) consisting of fine-medium-coarse sands. The results give a useful first approximation of the transmissivity and could be used to site exploratory boreholes.
文摘Global dimming term was introduced in 1990s which means the decline in global radiation. This decline was reported in several studies across the world. In the present study time series analysis of global radiation (1960-2003), transmissivity (1960-2003) and bright sunshine hours (1973-2003) has been done over Nagpur during pre-monsoon (March to May) and monsoon seasons (June-September). A significant decrease in global radiation and transmissivity has been reported for both the seasons and it was higher during pre-monsoon compared to monsoon. Bright sunshine hour has also shown good agreement with the previous trend with a significant trend on pre-monsoon months only. Mann Kendall test was performed to confirm the significance of reported trend.
文摘This study was undertaken to determine the hydrologic properties of the aquifer materials at Ogbozara-Opi/Ekwegbe-Agu and environs by the estimation of the aquifer transmissivity using Dar Zarrouk parameters. The study area lies in the Anambra basin and is underlain, from bottom to top, by 3 prominent geologic formations;Enugu Formation, Mamu Formation and Ajali Formation respectively. A total of 19 sounding stations were occupied within the study area using the Ohmega resistivity meter. The VES data were interpreted using the conventional partial curve matching technique to obtain initial model parameters which were later used as input data for computer iterative modelling using the Interpex software. These analyses were further combined with information from two existing boreholes in the study area to estimate aquifer hydraulic parameters using Dar-Zarrouk parameters. The layer parameters thus obtained revealed that the dominant curve type obtained from the different formations is the AK curve type followed by the HK curve type. An average of 6 geo-electric layers were delineated across all transect taken with resistivity values ranging from 25.42 - 105.85 Ωm, 186.38 - 3383.3 Ωm and 2992.3 - 6286.4 Ωm in the Enugu, Mamu and Ajali Formations respectively. Results of the study revealed the aquifer resistivity in the study area ranges from 1 - 500 Ωm. The depth to the water table range from 13 - 208 m with a mean value of 76.05, while aquifer thickness varies between 95 and 140 m with a mean value of 102.89 m. The values of the Dar-Zarrouk parameters revealed that the transverse resistance varies between −10,000 - 170,000 Ωm<sup>2</sup>, while the longitudinal conductance varies from 0.1 - 1 to 1.9 Ω - 1. Similarly, the hydraulic conductivity in the area ranges from 5 to 50 m/day, while the transmissivity values range from 1000 to 14,000 m<sup>2</sup>/day.
基金supported by the National Basic Research Program of China(Grant No.2013CB733406)the National Natural Science Foundations of China(Grant No.41171266)
文摘Forests play an important role in the global carbon cycle and have a potential impact on global climatic change.Monitoring forest biomass is of considerable importance in understanding the hydrological cycle.Because of the problem of dense forest cover,no reliable method with which to retrieve soil moisture in forest areas from the microwave emission signature has been established.All of these issues relate to the microwave emissivity and transmissivity characteristics of a forest.The microwave emission contribution received by a sensor above a forest canopy comes from both the soil surface and the vegetation layer.To analyze the relationship of forest biomass and forest emission and transmissivity,a high-order emission model,the matrix-doubling model,which consists of both soil and vegetation models,was developed and then validated for a young deciduous forest stand in a field experiment.To simulate the emissivity and transmissivity of a deciduous forest in the L and X bands using the matrix-doubling model,the parameters of components of deciduous trees when the leaf area index varies from 1 to10 were generated by an L-system and a forest growth model.The emissivity and transmissivity of a forest and the relationships of these parameters to forest biomass are presented and analyzed in this paper.Emissivity in the L band when the leaf area index is less than 6 and at viewing angles less than 40°,and transmissivity in the L band are the most sensitive parameters in deciduous forest biomass estimation.
基金supported by National Natural Science Foundation of China:[Grant Number 41771400]National Natural Science Foundation of China:[Grant Number 41871248]Science and Technology Basic Resources Investigation Program of China‘Investigation on snow characteristics and their distribution in China’[Grant Number 2017FY100500].
文摘Forests have invariably been considered as an obstacle in retrieving land surface parameters from spaceborne passive microwave brightness temperature(T_(B))observations.For quantifying the effect of forests on microwave signals,several models have been developed.However,these models rarely reveal the dependence of microwave radiation on forest types,which can hardly meet the needs of high-accuracy retrieval of terrestrial parameters in forested regions.A ground-based microwave radiometric observation experiment was designed to investigate the dependence of microwave radiation on frequency,polarization,and forest type.Downward TB at 18.7-and 36.5-GHz for horizontal-and vertical-polarization from the forest canopy was measured at 14 sample plots in Northeast China,along with snowpack and forest structural parameters.By providing fits to experimental data,new empirical transmissivity models for three forest types were developed,as a function of woody stem volume and depending on the frequency/polarization.The proposed models give diverse asymptotic transmissivity saturation levels and the corresponding saturation point of woody stem volume for different forest types.Root-mean-square error results between T_(B) simulations and Advanced Microwave Scanning Radiometer-2 observations are approximately 3-6 K.This study provides an experimental and theoretical reference for further development of inversion models for snow parameters in forested areas.
文摘Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
文摘In this paper,we propose a random access scheme termed sign-compute diversity slotted ALOHA(SCDSA).The SCDSA scheme combines diversity transmission with compute-and-forward.Without considering the capture effect and multiple user detection techniques,our scheme can reach a high throughput of 0.98 without feedback under finite frame size settings,where the upper bound on performance is 1.Moreover,a lower bound on throughput performance is derived,which is tight in some parameter settings and can be used to approximate theoretical performance.Simulation results validate our analysis and confirm the advantages of our proposed scheme.
基金National Natural Science Foundation of China(Grant Nos.42388102,42030105,42192535)the Open Fund of State Key Laboratory of Precision Geodesy,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences(Grant No.SKLPG2025-1-5)。
文摘The state-of-the-art optical atomic clocks and the time-frequency signal transmission open a fresh field for gravity potential(geopotential)determination.Various methods,including optical fiber frequency transfer,satellite two-way,satellite common-view,satellite carrier phase,VLBI,tri-frequency combination,and dual-frequency combination,were developed to determine the geopotential differences using optical atomic clocks and then determine the geopotential at station B based on the geopotential at station A.This review elaborates the principles,methods,scientific objectives,applications,and relevant research trends of geopotential determination based on time-frequency signals.
基金funded by the National Natural Science Foundation of China(32160123 and 32170974)Jiangxi Provincial Key Project of Natural Science Foundation(20212ACB205002)Jiangxi Provincial Key Laboratory of Organic Functional Molecules(2024SSY05141)。
文摘Gynandromorphs,rare in vertebrates,exhibit distinct sex-determining gene expression on each side of the body despite sharing a uniform hormonal environment.This provides a unique opportunity to investigate the respective roles of genes and hormones in sex determination.We accidently obtained a gynandromorphic Zebra Finch with a male-female chimeric appearance but only with an ovary-like gonad.Its plasma estradiol was significantly higher than that of age-matched females,and its sexual partner preference was also feminine.Although it did not sing like males,its calls showed masculinization.In the brain on one side of the body with male plumage,the area of song motor nucleus,the robust nucleus of the arcopallium(RA),and the excitatory synaptic transmission of RA projection neurons showed masculinization.Transcriptome analysis revealed that genes related to cholinergic neuron function were significantly upregulated in the masculinized side of brain.Moreover,there were extensive and consistent expression differences of neuroactive substance receptor genes in both sides of body,indicating that cell-autonomous determination plays a key role in sex dimorphism of neuromodulation.
基金the support from the National Natural Science Foundation of China (Nos. U20A20274, 52061003)the Natural Science Foundation of Yunnan Province, China (No. 202301AT070209)the Science and Technology Major Project of Yunnan Province, China (No. 202102AG050017)。
文摘The age-hardening response,mechanical,and corrosion-resistant properties of AA7085 alloys with and without the addition of 0.3 wt.%scandium(Sc)were compared.Using advanced techniques such as aberration-corrected transmission electron microscopy and first-principles calculations,the underlying micromechanisms of Sc microalloying were revealed.Results show that the increase in strength of the AA7085-Sc alloy is mainly attributed to the decreased Al grain size and increased number density of both Al_(3)Sc@Al_(3)(Sc,Zr)core−shell nanoparticles and Sc-containingη_(p) and GP−η_(p) nanoprecipitates.Strong strain fields and evident electron transfer from Zr to the neighboring matrix Al atoms exist at the Al_(3)Sc@Al_(3)(Sc,Zr)/Al interface.The Sc doping in GP−η_(p) andη_(p) suppresses the GP−η_(p)→η_(p) transformation.Modified corrosion resistance of the AA7085-Sc alloy compared with AA7085 alloy is associated with the fine grain boundary precipitates ofη_(p)hases and narrow precipitation free zone.The reasons of property changes of AA7085 alloy after Sc microalloying are explored based on the multiscale microstructural characterization.
基金National Natural Science Foundation of China(Grant No.52278121).
文摘The cold chain environment is an important route for the long⁃distance transmission of pathogenic micro⁃organisms.In this study,we explored the mechanisms of secondary propagation through surface contact on cold surfaces.A quantitative statistical experimental method was adopted to study the surface⁃contact transmission of micro⁃organisms,wherein the transfer rate of surface contact was the dependent variable and Escherichia coli was used as the indicator bacterium.The effects of contact pressure(0.44,0.86,1.55,2.25,and 2.94 N/cm^(2)),contact time(0,15,30,45,and 60 s),contact angle(15°and 25°),and surface materials(rubber and cotton gloves)were measured at two storage temperatures:cold storage(5℃)and freezing(-18℃).The results showed that as temperature decreases,the transfer of micro⁃organisms through surface contact becomes less probable.The contact time did not significantly influence the transfer rate of micro⁃organisms when items were handled at cold⁃storage temperatures.Based on these results,we recommend placing items as flat as possible to minimize the tilt angle when handling them at cold⁃storage temperatures.Additionally,if the tilt angle cannot be avoided,rubber gloves should be used when handling items stored at large tilt angles,whereas cotton gloves may be used for items placed at smaller angles.
基金supported by Science and Technology Project of the headquarters of the State Grid Corporation of China(No.5500-202324492A-3-2-ZN).
文摘To enhance power flow regulation in scenarios involving large-scale renewable energy transmission via high-voltage direct current(HVDC)links and multi-infeed DC systems in load-center regions,this paper proposes a hybrid modular multilevel converter–capacitor-commutated line-commutated converter(MMC-CLCC)HVDC transmission system and its corresponding control strategy.First,the system topology is constructed,and a submodule configuration method for the MMC—combining full-bridge submodules(FBSMs)and half-bridge submodules(HBSMs)—is proposed to enable direct power flow reversal.Second,a hierarchical control strategy is introduced,includingMMCvoltage control,CLCC current control,and a coordinationmechanism,along with the derivation of the hybrid system’s power flow reversal characteristics.Third,leveraging the CLCC’s fast current regulation and theMMC’s negative voltage control capability,a coordinated power flow reversal control strategy is developed.Finally,an 800 kV MMC-CLCC hybrid HVDC system is modeled in PSCAD/EMTDC to validate the power flow reversal performance under a high proportion of full-bridge submodule configuration.Results demonstrate that the proposed control strategy enables rapid(1-s transition)and smooth switching of bidirectional power flow without modifying the structure of primary equipment:the transient fluctuation ofDC voltage from the rated value(UdcN)to themaximumreverse voltage(-kUdcN)is less than 5%;the DC current strictly follows the preset characteristic curve with a deviation of≤3%;the active power reverses continuously,and the system maintains stable operation throughout the reversal process.
基金supported by the National Key Research&Development Program of China(2022YFC3602700,2022YFC3602702)the Science and Technology Innovation 2030-Brain Science and Brain-Inspired Intelligence Project(2021ZD0201301)+2 种基金the National Natural Science Foundation of China(12034015,62088101,32170688,323B1004)Program of Shanghai Academic Research Leader(21XD1403600)Shanghai Municipal Science and Technology Major Project(2021SHZDZX0100,2018SHZDZX01).
文摘Ultrasound neuromodulation shows promise for treating neurological disorders,but the underlying mechanisms remain unclear.Here,we developed an integrated surface acoustic wave(SAW)ultrasound chip enabling simultaneous electrophysiological recording and Ca^(2+) imaging of cultured hippocampal neurons to investigate neuronal excitability and synaptic transmission during ultrasound stimulation.This study revealed,for the first time,three distinct neuronal response patterns induced by SAW ultrasound:an immediate response showing rapid activation,a delayed response exhibiting facilitation after several minutes,and a non-response maintaining baseline activity.Ultrasound stimulation increased action potential firing,enhanced excitatory postsynaptic currents,and elevated intracellular Ca^(2+) levels.These effects were dependent on extracellular Ca^(2+) influx and primarily dominated by L-type Ca^(2+) channels.Our findings suggest that individual neurons exhibit heterogeneous responses to SAW ultrasound stimulation based on their intracellular Ca^(2+) levels and L-type Ca^(2+) channel activity.This integrated approach provides new insights into the cellular mechanisms of ultrasound neuromodulation while highlighting the potential of SAW technology for precise,cell-type-specific neural control.
基金supported by the Natural Science Foundation of China(Grant No.52275091)Natural Science Foundation of Liaoning Province(Grant No.2022-MS-125)+1 种基金Shenyang Natural Science Foundation(Grant No.23-503-6-02)Fundamental Research Funds for the Central Universities(Grant No.N2303011).
文摘Inspired that kangaroo can buffer the impact and absorb vibration from the ground and keep the whole-body stable,an integrated kangaroo bio-inspired vibration suppression(IKBVS)structure considering vibration isolation-absorption simultaneously is proposed for low/wide band frequency vibration control.Based on skeleton mass,articulation friction,and the synergistic action among skeleton,articulation,and muscle/tendon,a vibration suppression model with more biological basic characteristics is derived.The validity of model and method is confirmed,and the static and dynamic analysis of the IKBVS system is carried out to investigate the vibration suppression performance.The quasi-zero stiffness region can be achieved with a smaller initial installation angle,medium rod length,smaller foot stiffness,and slightly lighter isolated mass in a wide displacement interval.The coupling mechanism of vibration isolation-absorption is revealed by parameter analysis.The results indicate that the IKBVS structure has favorite dynamic properties due to adjustable nonlinearity,namely,lower and adjustable resonance and anti-resonance frequency/peak and different levels of vibration suppression effect in high-frequency range are achieved readily.This research provides new insight into application of bio-inspired vibration suppression structures in various engineering systems for better vibration control.
基金supported by the Quantum Science and Technology-National Science and Technology Major Project of China(Grant No.2024ZD0301000)the National Natural Science Foundation of China(Grant No.12275136)。
文摘The Stern-Gerlach(SG)experiment is a fundamental experiment for revealing the existence of“spin”.In this experiment,beams of silver atoms are sent through inhomogeneous magnetic fields to observe their deflection.Thus,the conventional SG experiment can be viewed as a magnetic-type spin effect.In this work,we successfully generalize the SG effect from magnetic-type to electric-type by solving Dirac's equation with a potential barrier,revealing an extraordinary spin effect.Beams of Dirac particles can be regarded as matter waves.Based on Dirac's equation,we obtain the explicit forms of the incident,reflected,and transmitted waves.The electric-type SG effect shows that the reflected and transmitted waves can exhibit notable spatial shifts,which depend on the spin direction and the incident angle of the wave.The electrictype SG effect has potential applications for separating Dirac particles with different spin directions and for estimating the spin direction of Dirac particles.Some discussions related to the interaction between spin and the electric field are also presented.
基金supported by the Guangdong Major Project of Basic Research(Grant No.2020B0301030009)the National Natural Science Foundation of China(Grant Nos.12174204,12174203,12074203,62335012,and 62435010)+5 种基金the Natural Science Foundation of Guangdong Province(Grant No.2023A1515012888)the Science and Technology Innovation Commission of Shenzhen(Grant Nos.JCYJ20220818101417039 and JCYJ20241202124428038)the Medical-Engineering Interdisciplinary Research Foundation of Shenzhen University(Grant No.86901/00000311)the Scientific Instrument Developing Project of Shenzhen University(Grant No.2023YQ001)the Shenzhen University 2035 Initiative(Grant No.2023B004)the Key R&D Program of Zhejiang(Grant No.30003AA240100)。
文摘Speckle-based optical cryptosystems are promising technologies for information security.However,existing techniques mostly rely on digital decryption,resulting in computational delay and undermining the high-speed advantage of optical encryption.Moreover,conventional neural networks are typically effective only on images from the same distribution as the training datasets,limiting their general applicability.In this paper,we propose an all-optical high-speed decryption scheme for real-time recovery of speckle-encoded ciphertexts.By constructing a physics-informed diffractive neural network that approximates the inverse transmission matrix of the scattering medium,secret images can be directly reconstructed from speckle fields without optoelectronic conversion or post-processing.The network is trained with only 2048 samples from the MNIST dataset.Its transfer learning capability is validated across three out-of-distribution datasets,with decrypted images achieving a Pearson correlation coefficient of 0.82 and a structural similarity index measure of 0.75,demonstrating excellent transfer learning capability.For the first time,to our knowledge,this scheme simultaneously overcomes the bottlenecks of decryption delay and limited network generalizability in conventional speckle-based cryptosystems,achieving real-time image decryption with strong transferability.It provides a new pathway for developing low-power,real-time,and broadly applicable optical encryption systems,demonstrating significant potential for applications in high-speed security optical communications.
文摘Wireless Sensor Networks(WSNs)have become foundational in numerous real-world applications,ranging from environmental monitoring and industrial automation to healthcare systems and smart city development.As these networks continue to grow in scale and complexity,the need for energy-efficient,scalable,and robust communication protocols becomes more critical than ever.Metaheuristic algorithms have shown significant promise in addressing these challenges,offering flexible and effective solutions for optimizing WSN performance.Among them,the Grey Wolf Optimizer(GWO)algorithm has attracted growing attention due to its simplicity,fast convergence,and strong global search capabilities.Accordingly,this survey provides an in-depth review of the applications of GWO and its variants for clustering,multi-hop routing,and hybrid cluster-based routing in WSNs.We categorize and analyze the existing GWO-based approaches across these key network optimization tasks,discussing the different problem formulations,decision variables,objective functions,and performance metrics used.In doing so,we examine standard GWO,multi-objective GWO,and hybrid GWO models that incorporate other computational intelligence techniques.Each method is evaluated based on how effectively it addresses the core constraints of WSNs,including energy consumption,communication overhead,and network lifetime.Finally,this survey outlines existing gaps in the literature and proposes potential future research directions aimed at enhancing the effectiveness and real-world applicability of GWO-based techniques for WSN clustering and routing.Our goal is to provide researchers and practitioners with a clear,structured understanding of the current state of GWO in WSNs and inspire further innovation in this evolving field.
