High-selectivity common-mode(CM)and differential-mode(DM)reflectionless balanced bandpass filters(BBPFs)are proposed in this article.By loading absorption networks at single/both ends of the basic ring resonator,input...High-selectivity common-mode(CM)and differential-mode(DM)reflectionless balanced bandpass filters(BBPFs)are proposed in this article.By loading absorption networks at single/both ends of the basic ring resonator,input-/two-port wideband CM and DM reflectionless performance,wideband filtering performance and all-stop CM suppression are obtained.The absorption network composed of K-sections of coupled-lines(CLs)terminated with grounded resistors can not only extend the filtering performance to high order,but also realize wideband absorption of CM noise and out-of-band DM signals.Absorptive stubs are loaded at ports to increase the design flexibility and enhance the absorption.As for the input-reflectionless type,multiple independently controlled transmission zeros(TZs)are obtained by the TZ control network to improves the selectivity and out-of-band rejection.A set of 2 GHz micro-strip BBPFs are designed and measured,which shows simultaneous CM and DM absorption performance.展开更多
In-loop filters have been comprehensively explored during the development of video coding standards due to their remarkable noise-reduction capabilities.In the early stage of video coding,in-loop filters,such as the d...In-loop filters have been comprehensively explored during the development of video coding standards due to their remarkable noise-reduction capabilities.In the early stage of video coding,in-loop filters,such as the deblocking filter,sample adaptive offset,and adaptive loop filter,were performed separately for each component.Recently,cross-component filters have been studied to improve chroma fidelity by exploiting correlations between the luma and chroma channels.This paper introduces the cross-component filters used in the state-ofthe-art video coding standards,including the cross-component adaptive loop filter and cross-component sample adaptive offset.Crosscomponent filters aim to reduce compression artifacts based on the correlation between different components and provide more accurate pixel reconstruction values.We present their origin,development,and status in the current video coding standards.Finally,we conduct discussions on the further evolution of cross-component filters.展开更多
In this paper,the newly-derived maximum correntropy Kalman filter(MCKF)is re-derived from the M-estimation perspective,where the MCKF can be viewed as a special case of the M-estimations and the Gaussian kernel functi...In this paper,the newly-derived maximum correntropy Kalman filter(MCKF)is re-derived from the M-estimation perspective,where the MCKF can be viewed as a special case of the M-estimations and the Gaussian kernel function is a special case of many robust cost functions.Based on the derivation process,a unified form for the robust Gaussian filters(RGF)based on M-estimation is proposed to suppress the outliers and non-Gaussian noise in the measurement.The RGF provides a unified form for one Gaussian filter with different cost functions and a unified form for one robust filter with different approximating methods for the involved Gaussian integrals.Simulation results show that RGF with different weighting functions and different Gaussian integral approximation methods has robust antijamming performance.展开更多
Pure magnesia filter and periclase-spinel filter were prepared using porous MgO powder and Al2O3 micro-powder as raw materials.The filtration efficiency and purification mechanism of the two sets of filters on molten ...Pure magnesia filter and periclase-spinel filter were prepared using porous MgO powder and Al2O3 micro-powder as raw materials.The filtration efficiency and purification mechanism of the two sets of filters on molten steel were investigated through steel casting tests.The results show that on the basis of surviving the thermal shock of molten steel,both filters can significantly reduce the number of non-metallic inclusions and total oxygen content of steel,thereby improving the cleanliness of the molten steel.After the thermal shock of molten steel,cracks were found in the microstructure of pure magnesia filter.Via the diffusion of non-metallic inclusions from steel into MgO grains of the filter to form solid solution,the inclusions were adsorbed to the internal and external surfaces of the pure magnesia filter.The number of inclusions was reduced by 62.5%,and the total oxygen content decreased from 0.892 to 0.265 wt.%after filtration,achieving a filtration efficiency of 70.3%.Compared with the pure magnesia filter,no cracks were found in the microstructure of the periclase-spinel filter.The mass transfer rate was accelerated due to the diffusion of inclusions from steel into MgO and MgAl2O4 grains of the filter,as well as the higher high-temperature liquid content and smaller pore structure of the filter.More non-metallic inclusions were able to enter the interior of the filter,which made the periclase-spinel filter more capable of adsorbing inclusions from steel and reducing total oxygen content.The periclase-spinel filter reduced the number of inclusions in steel by 84.4%and decreased the total oxygen content of the steel from 0.892 to 0.119 wt.%,with a filtration efficiency of 86.7%,demonstrating excellent comprehensive performance.展开更多
Rationale: Endotoxin contamination in conventionally purified water poses serious risks to hemodialysis patients, leading to complications such as inflammation and sepsis. Addressing these risks is essential for enhan...Rationale: Endotoxin contamination in conventionally purified water poses serious risks to hemodialysis patients, leading to complications such as inflammation and sepsis. Addressing these risks is essential for enhancing patient safety and meeting global dialysis water quality standards. Advanced filtration technologies, such as titanium dioxide (TiO₂)-based nanoparticle filters, offer a promising approach to improve water purification processes in renal care. Objectives: This study aimed to develop and evaluate the effectiveness of a TiO₂-based nanoparticle microporous filtration system for hemodialysis water purification. The objectives included analyzing the system’s performance in reducing chemical contaminants (calcium, magnesium, aluminum, and lead) and microbiological contaminants (total viable count [TVC] and endotoxin units [EU]) across multiple renal centers. Methods: Water samples from three renal centers (RC1, RC2, and RC3) were analyzed pre- and post-filtration. TiO₂ nanoparticles were synthesized using the sol-gel method and characterized via Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM/EDX). The microporous filter, fabricated with TiO₂ nanoparticles, silicon dioxide, and polyethylene glycol (PEG), was tested for its ability to remove contaminants. Analytical techniques included spectroscopy for chemical analysis and microbiological assays for contaminant quantification. Results: Post-treatment analysis revealed significant reductions in chemical contaminants, with removal efficiencies averaging 78% for calcium, 80% for magnesium, 81% for aluminum, and 76.6% for lead across all centers. Microbiological contamination was also substantially reduced, with 78–80% removal of TVC and 76–84.6% reduction in EU levels. FTIR analysis confirmed the presence of hydroxyl groups critical for adsorption, while SEM/EDX characterization revealed a crystalline structure with a particle size of 1.45 nm, pore size of 4.11 μm, filter height of 2.56 mm, and bulk density of 0.58 g/cm³. Conclusion: The TiO₂-based nanoparticle filtration system demonstrated high efficacy in removing chemical and microbiological contaminants, significantly improving water quality for hemodialysis. These results highlight its potential as a practical solution for renal centers, especially in resource-constrained settings. Further studies are needed to evaluate its long-term performance and feasibility for widespread adoption. Recommendation: Renal centers should consider adopting TiO2-based nanoparticle filters to address persistent water quality challenges. Pilot implementations across diverse settings can provide insights into operational feasibility. Additional research should explore scalability, maintenance requirements, and cost-effectiveness to optimize integration into healthcare systems. Significance Statement: This study introduces a practical and innovative solution to improve hemodialysis water purification. By effectively reducing both chemical and microbiological contaminants, the TiO2-based filtration system has the potential to enhance patient safety and outcomes, particularly in settings where maintaining high water quality standards remains challenging.展开更多
In digital signal processing,image enhancement or image denoising are challenging task to preserve pixel quality.There are several approaches from conventional to deep learning that are used to resolve such issues.But...In digital signal processing,image enhancement or image denoising are challenging task to preserve pixel quality.There are several approaches from conventional to deep learning that are used to resolve such issues.But they still face challenges in terms of computational requirements,overfitting and generalization issues,etc.To resolve such issues,optimization algorithms provide greater control and transparency in designing digital filters for image enhancement and denoising.Therefore,this paper presented a novel denoising approach for medical applications using an Optimized Learning⁃based Multi⁃level discrete Wavelet Cascaded Convolutional Neural Network(OLMWCNN).In this approach,the optimal filter parameters are identified to preserve the image quality after denoising.The performance and efficiency of the OLMWCNN filter are evaluated,demonstrating significant progress in denoising medical images while overcoming the limitations of conventional methods.展开更多
Jamming suppression is traditionally achieved through the use of spatial filters based on array signal processing theory.In order to achieve better jamming suppression performance,many studies have applied blind sourc...Jamming suppression is traditionally achieved through the use of spatial filters based on array signal processing theory.In order to achieve better jamming suppression performance,many studies have applied blind source separation(BSS)to jamming suppression.BSS can achieve the separation and extraction of the individual source signals from the mixed signal received by the array.This paper proposes a perspective to recognize BSS as spatial band-pass filters(SBPFs)for jamming suppression applications.The theoretical derivation indicates that the processing of mixed signals by BSS can be perceived as the application of a set of SBPFs that gate the source signals at various angles.Simulations are performed using radar jamming suppression as an example.The simulation results suggest that BSS and SBPFs produce approximately the same effects.Simulation results are consistent with theoretical derivation results.展开更多
MnCeO_(x)/P84 catalytic filters with spherical,flower-like,cubic and rod-like catalytic interfaces were synthesized respectively,and their catalytic activities in the NH_(3)-SCR reaction were investigated.The MnCeO_(x...MnCeO_(x)/P84 catalytic filters with spherical,flower-like,cubic and rod-like catalytic interfaces were synthesized respectively,and their catalytic activities in the NH_(3)-SCR reaction were investigated.The MnCeO_(x)/P84 catalytic filter with spherical catalytic interfaces(recorded as S-MnCeO_(x)/P84)exhibits the best catalytic denitration performance.The NO_(x)removal efficiency of S-MnCeO_(x)/P84 reaches the highest value of 98.6%at 160℃when the catalyst loading is 100 g/m^(2).At the same time,S-MnCeO_(x)/P84 exhibits good SO_(2)resistance and stability,achieving a NO_(x)removal rate of 83%at 190℃with 30 ppm SO_(2).The characterization results illustrate that the MnCeO_x active component in S-MnCeO_(x)/P84 is present in weak crystalline states,tightly wrapped around the surface of the filter fiber,and uniformly dispersed,and the mesopore is the main pore structure of the S-MnCeO_(x)/P84,which can provide a channel for the catalytic reaction to proceed.At the same time,transmission electron microscopy(TEM)characterization shows that y-MnO_(2)is the main form of MnO_(2)in the S-MnCeO_(x)/P84.Further analysis of H_(2)temperature programmed reduction(H_(2)-TPR).NH_(3)temperature programmed desorption(NH_(3)-TPD)and in-situ diffuse reflectance infrared spectra(DRIFTS)show that S-MnCeO_(x)/P84 has good redox ability at 100-200℃and has abundant Lewis acid sites and Bronsteds acid sites,which provides an important guarantee for its superior low-temperature NH_(3)-SCR denitration performance.展开更多
Understanding plant community assembly is crucial for effective ecosystem conservation and restoration.The ecological filter framework describes community assembly as a process shaped by dispersal,environmental,and bi...Understanding plant community assembly is crucial for effective ecosystem conservation and restoration.The ecological filter framework describes community assembly as a process shaped by dispersal,environmental,and biotic filters.Additionally,functional traits and phylogenetic relationships are increasingly recognized as important factors influencing species coexistence and community structure.However,both the ecological filter framework and the roles of functional traits and phylogeny in community assembly remain underexplored in the Algerian steppes—particularly in the El Bayadh region,where ongoing vegetation degradation threatens ecosystem stability.This study applied Hierarchical Modeling of Species Communities(HMSC)as an integrative approach to assess how ecological filters influence plant community assembly in the El Bayadh steppe and to evaluate the roles of functional traits and phylogenetic relationships in this process.Environmental data—including soil properties,topography,precipitation,and land use types(grazing and exclosure)—were collected across 50 plots in April and October,2023,along with functional traits from 24 species.These traits include root length,leaf area,specific leaf area,clonality,life history,and seed mass.HMSC results revealed that soil properties and precipitation were the primary drivers of community structure,while sand height and elevation had a moderate influence.In contrast,competition and grazing played relatively minor roles.Species responses to environmental covariates were heterogeneous:soil fertility and texture had mixed effects,benefiting some species while limiting others;sand encroachment and precipitation variability generally had negative impacts,whereas grazing exclusion favored many species.A weak phylogenetic signal was recorded,indicating that community assembly was driven more by environmental filtering than by shared evolutionary history.Functional trait responses to environmental variation reflected plant strategies that balanced resource acquisition and conservation.Specifically,seed mass,leaf area,and root length increased under higher soil moisture and nutrient availability but declined in response to salinity,precipitation variability,and sand height.Clonality and perennial life history traits enhanced the survival of plant species under harsh conditions.Overall,this study provides a holistic understanding of community assembly processes in the El Bayadh steppe and offers valuable insights for ecosystem management and restoration in arid and degraded ecosystem environments.展开更多
This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utiliz...This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.展开更多
文摘High-selectivity common-mode(CM)and differential-mode(DM)reflectionless balanced bandpass filters(BBPFs)are proposed in this article.By loading absorption networks at single/both ends of the basic ring resonator,input-/two-port wideband CM and DM reflectionless performance,wideband filtering performance and all-stop CM suppression are obtained.The absorption network composed of K-sections of coupled-lines(CLs)terminated with grounded resistors can not only extend the filtering performance to high order,but also realize wideband absorption of CM noise and out-of-band DM signals.Absorptive stubs are loaded at ports to increase the design flexibility and enhance the absorption.As for the input-reflectionless type,multiple independently controlled transmission zeros(TZs)are obtained by the TZ control network to improves the selectivity and out-of-band rejection.A set of 2 GHz micro-strip BBPFs are designed and measured,which shows simultaneous CM and DM absorption performance.
基金supported in part by National Science Foundation of China under Grant No.62031013PCL-CMCC Foundation for Science and Innovation under Grant No.2024ZY1C0040+1 种基金New Cornerstone Science Foundation for the Xplorer PrizeHigh performance Computing Platform of Peking University。
文摘In-loop filters have been comprehensively explored during the development of video coding standards due to their remarkable noise-reduction capabilities.In the early stage of video coding,in-loop filters,such as the deblocking filter,sample adaptive offset,and adaptive loop filter,were performed separately for each component.Recently,cross-component filters have been studied to improve chroma fidelity by exploiting correlations between the luma and chroma channels.This paper introduces the cross-component filters used in the state-ofthe-art video coding standards,including the cross-component adaptive loop filter and cross-component sample adaptive offset.Crosscomponent filters aim to reduce compression artifacts based on the correlation between different components and provide more accurate pixel reconstruction values.We present their origin,development,and status in the current video coding standards.Finally,we conduct discussions on the further evolution of cross-component filters.
基金supported by the Basic Science Center Program of the National Natural Science Foundation of China(62388101)the National Natural Science Foundation of China(61873275).
文摘In this paper,the newly-derived maximum correntropy Kalman filter(MCKF)is re-derived from the M-estimation perspective,where the MCKF can be viewed as a special case of the M-estimations and the Gaussian kernel function is a special case of many robust cost functions.Based on the derivation process,a unified form for the robust Gaussian filters(RGF)based on M-estimation is proposed to suppress the outliers and non-Gaussian noise in the measurement.The RGF provides a unified form for one Gaussian filter with different cost functions and a unified form for one robust filter with different approximating methods for the involved Gaussian integrals.Simulation results show that RGF with different weighting functions and different Gaussian integral approximation methods has robust antijamming performance.
基金supported by the Key Project of the National Natural Science Foundation of China(Grant No.U21A2058 and U1860205)the Natural Science Funds of Hubei Province for Distinguished Young Scholars(Grant No.2020CFA088).
文摘Pure magnesia filter and periclase-spinel filter were prepared using porous MgO powder and Al2O3 micro-powder as raw materials.The filtration efficiency and purification mechanism of the two sets of filters on molten steel were investigated through steel casting tests.The results show that on the basis of surviving the thermal shock of molten steel,both filters can significantly reduce the number of non-metallic inclusions and total oxygen content of steel,thereby improving the cleanliness of the molten steel.After the thermal shock of molten steel,cracks were found in the microstructure of pure magnesia filter.Via the diffusion of non-metallic inclusions from steel into MgO grains of the filter to form solid solution,the inclusions were adsorbed to the internal and external surfaces of the pure magnesia filter.The number of inclusions was reduced by 62.5%,and the total oxygen content decreased from 0.892 to 0.265 wt.%after filtration,achieving a filtration efficiency of 70.3%.Compared with the pure magnesia filter,no cracks were found in the microstructure of the periclase-spinel filter.The mass transfer rate was accelerated due to the diffusion of inclusions from steel into MgO and MgAl2O4 grains of the filter,as well as the higher high-temperature liquid content and smaller pore structure of the filter.More non-metallic inclusions were able to enter the interior of the filter,which made the periclase-spinel filter more capable of adsorbing inclusions from steel and reducing total oxygen content.The periclase-spinel filter reduced the number of inclusions in steel by 84.4%and decreased the total oxygen content of the steel from 0.892 to 0.119 wt.%,with a filtration efficiency of 86.7%,demonstrating excellent comprehensive performance.
文摘Rationale: Endotoxin contamination in conventionally purified water poses serious risks to hemodialysis patients, leading to complications such as inflammation and sepsis. Addressing these risks is essential for enhancing patient safety and meeting global dialysis water quality standards. Advanced filtration technologies, such as titanium dioxide (TiO₂)-based nanoparticle filters, offer a promising approach to improve water purification processes in renal care. Objectives: This study aimed to develop and evaluate the effectiveness of a TiO₂-based nanoparticle microporous filtration system for hemodialysis water purification. The objectives included analyzing the system’s performance in reducing chemical contaminants (calcium, magnesium, aluminum, and lead) and microbiological contaminants (total viable count [TVC] and endotoxin units [EU]) across multiple renal centers. Methods: Water samples from three renal centers (RC1, RC2, and RC3) were analyzed pre- and post-filtration. TiO₂ nanoparticles were synthesized using the sol-gel method and characterized via Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM/EDX). The microporous filter, fabricated with TiO₂ nanoparticles, silicon dioxide, and polyethylene glycol (PEG), was tested for its ability to remove contaminants. Analytical techniques included spectroscopy for chemical analysis and microbiological assays for contaminant quantification. Results: Post-treatment analysis revealed significant reductions in chemical contaminants, with removal efficiencies averaging 78% for calcium, 80% for magnesium, 81% for aluminum, and 76.6% for lead across all centers. Microbiological contamination was also substantially reduced, with 78–80% removal of TVC and 76–84.6% reduction in EU levels. FTIR analysis confirmed the presence of hydroxyl groups critical for adsorption, while SEM/EDX characterization revealed a crystalline structure with a particle size of 1.45 nm, pore size of 4.11 μm, filter height of 2.56 mm, and bulk density of 0.58 g/cm³. Conclusion: The TiO₂-based nanoparticle filtration system demonstrated high efficacy in removing chemical and microbiological contaminants, significantly improving water quality for hemodialysis. These results highlight its potential as a practical solution for renal centers, especially in resource-constrained settings. Further studies are needed to evaluate its long-term performance and feasibility for widespread adoption. Recommendation: Renal centers should consider adopting TiO2-based nanoparticle filters to address persistent water quality challenges. Pilot implementations across diverse settings can provide insights into operational feasibility. Additional research should explore scalability, maintenance requirements, and cost-effectiveness to optimize integration into healthcare systems. Significance Statement: This study introduces a practical and innovative solution to improve hemodialysis water purification. By effectively reducing both chemical and microbiological contaminants, the TiO2-based filtration system has the potential to enhance patient safety and outcomes, particularly in settings where maintaining high water quality standards remains challenging.
文摘In digital signal processing,image enhancement or image denoising are challenging task to preserve pixel quality.There are several approaches from conventional to deep learning that are used to resolve such issues.But they still face challenges in terms of computational requirements,overfitting and generalization issues,etc.To resolve such issues,optimization algorithms provide greater control and transparency in designing digital filters for image enhancement and denoising.Therefore,this paper presented a novel denoising approach for medical applications using an Optimized Learning⁃based Multi⁃level discrete Wavelet Cascaded Convolutional Neural Network(OLMWCNN).In this approach,the optimal filter parameters are identified to preserve the image quality after denoising.The performance and efficiency of the OLMWCNN filter are evaluated,demonstrating significant progress in denoising medical images while overcoming the limitations of conventional methods.
基金supported by the National Natural Science Foundation of China(6237104662201048)the Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxmX0260).
文摘Jamming suppression is traditionally achieved through the use of spatial filters based on array signal processing theory.In order to achieve better jamming suppression performance,many studies have applied blind source separation(BSS)to jamming suppression.BSS can achieve the separation and extraction of the individual source signals from the mixed signal received by the array.This paper proposes a perspective to recognize BSS as spatial band-pass filters(SBPFs)for jamming suppression applications.The theoretical derivation indicates that the processing of mixed signals by BSS can be perceived as the application of a set of SBPFs that gate the source signals at various angles.Simulations are performed using radar jamming suppression as an example.The simulation results suggest that BSS and SBPFs produce approximately the same effects.Simulation results are consistent with theoretical derivation results.
基金Project supported by the National Natural Science Foundation of China(51902166)the Natural Science Foundation of Jiangsu Province(BK20190786)+1 种基金Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET)Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control。
文摘MnCeO_(x)/P84 catalytic filters with spherical,flower-like,cubic and rod-like catalytic interfaces were synthesized respectively,and their catalytic activities in the NH_(3)-SCR reaction were investigated.The MnCeO_(x)/P84 catalytic filter with spherical catalytic interfaces(recorded as S-MnCeO_(x)/P84)exhibits the best catalytic denitration performance.The NO_(x)removal efficiency of S-MnCeO_(x)/P84 reaches the highest value of 98.6%at 160℃when the catalyst loading is 100 g/m^(2).At the same time,S-MnCeO_(x)/P84 exhibits good SO_(2)resistance and stability,achieving a NO_(x)removal rate of 83%at 190℃with 30 ppm SO_(2).The characterization results illustrate that the MnCeO_x active component in S-MnCeO_(x)/P84 is present in weak crystalline states,tightly wrapped around the surface of the filter fiber,and uniformly dispersed,and the mesopore is the main pore structure of the S-MnCeO_(x)/P84,which can provide a channel for the catalytic reaction to proceed.At the same time,transmission electron microscopy(TEM)characterization shows that y-MnO_(2)is the main form of MnO_(2)in the S-MnCeO_(x)/P84.Further analysis of H_(2)temperature programmed reduction(H_(2)-TPR).NH_(3)temperature programmed desorption(NH_(3)-TPD)and in-situ diffuse reflectance infrared spectra(DRIFTS)show that S-MnCeO_(x)/P84 has good redox ability at 100-200℃and has abundant Lewis acid sites and Bronsteds acid sites,which provides an important guarantee for its superior low-temperature NH_(3)-SCR denitration performance.
基金supported by the Foundation of the University of Quebec in Abitibi-Témiscamingue(FUQAT)Quebec Research Fund(FRQ)(2021-SE7-282961)。
文摘Understanding plant community assembly is crucial for effective ecosystem conservation and restoration.The ecological filter framework describes community assembly as a process shaped by dispersal,environmental,and biotic filters.Additionally,functional traits and phylogenetic relationships are increasingly recognized as important factors influencing species coexistence and community structure.However,both the ecological filter framework and the roles of functional traits and phylogeny in community assembly remain underexplored in the Algerian steppes—particularly in the El Bayadh region,where ongoing vegetation degradation threatens ecosystem stability.This study applied Hierarchical Modeling of Species Communities(HMSC)as an integrative approach to assess how ecological filters influence plant community assembly in the El Bayadh steppe and to evaluate the roles of functional traits and phylogenetic relationships in this process.Environmental data—including soil properties,topography,precipitation,and land use types(grazing and exclosure)—were collected across 50 plots in April and October,2023,along with functional traits from 24 species.These traits include root length,leaf area,specific leaf area,clonality,life history,and seed mass.HMSC results revealed that soil properties and precipitation were the primary drivers of community structure,while sand height and elevation had a moderate influence.In contrast,competition and grazing played relatively minor roles.Species responses to environmental covariates were heterogeneous:soil fertility and texture had mixed effects,benefiting some species while limiting others;sand encroachment and precipitation variability generally had negative impacts,whereas grazing exclusion favored many species.A weak phylogenetic signal was recorded,indicating that community assembly was driven more by environmental filtering than by shared evolutionary history.Functional trait responses to environmental variation reflected plant strategies that balanced resource acquisition and conservation.Specifically,seed mass,leaf area,and root length increased under higher soil moisture and nutrient availability but declined in response to salinity,precipitation variability,and sand height.Clonality and perennial life history traits enhanced the survival of plant species under harsh conditions.Overall,this study provides a holistic understanding of community assembly processes in the El Bayadh steppe and offers valuable insights for ecosystem management and restoration in arid and degraded ecosystem environments.
基金supported by the Primary Research and Development Plan of Zhejiang Province (No.2023C03014)the Key Research and Development Program of Zhejiang Province (No.2022C03037)。
文摘This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.
