期刊文献+
共找到2,857篇文章
< 1 2 143 >
每页显示 20 50 100
Black Hole Complementarity in Terms of the Outsider and Insider Perspectives
1
作者 Eugene Terry Tatum 《Journal of Modern Physics》 2024年第2期184-192,共9页
A complementarity hypothesis concerning outsider and insider perspectives of a gargantuan black hole is proposed. The two thought experiments presented herein are followed by a brief discussion of a new interpretation... A complementarity hypothesis concerning outsider and insider perspectives of a gargantuan black hole is proposed. The two thought experiments presented herein are followed by a brief discussion of a new interpretation of black hole interior “space-and-time-reversal”. Specifically, it is proposed that the “singularity” space of the black hole interior is time-like and the expansion time of the black hole interior is space-like. The resemblance of this new insider interpretation to our own expanding and redshifting big bang universe is compelling. 展开更多
关键词 black Holes Complementarity Cosmological Models Rh = ct Models Flat Space Cosmology Schwarzschild Cosmology Thought Experiment Dark Energy Quantum Vacuum
下载PDF
Regulation of the growth of sprouting roots of black locust seedlings using root barrier panels 被引量:1
2
作者 Satoshi Kitaoka Shiro Matsunami +4 位作者 Yannan Wang Saki Fujita Kobayashi Makoto Toshiyuki Hirata Takayoshi Koike 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第3期655-664,共10页
How can we regulate an invasive alien species of high commercial value?Black locust(Robinia pseudoacacia L.)has a unique capacity for seed dispersal and high germination.Field surveys indicate that black locust increa... How can we regulate an invasive alien species of high commercial value?Black locust(Robinia pseudoacacia L.)has a unique capacity for seed dispersal and high germination.Field surveys indicate that black locust increases its growing area with sprouting roots and the elongation of horizontal roots at a soil depth of 10 cm.Therefore,a method to regulate the development of horizontal roots could be eff ective in slowing the invasiveness of black locust.In this study,root barrier panels were tested to inhibit the growth of horizontal roots.Since it is labor intensive to observe the growth of roots in the fi eld,it was investigated in a nursery setting.The decrease in secondary fl ush,an increase in yellowed leafl ets,and the height in the seedlings were measured.Installing root barrier panels to a depth of 30 cm eff ectively inhibit the growth of horizontal roots of young black locust. 展开更多
关键词 black locust Horizontal roots NUTRIENTS Root barrier panel Sprouting roots
下载PDF
About Worlds inside a Black Hole and Peculiarities of the Formation of Exotic Space Objects
3
作者 Avas Khugaev Eugeniya Bibaeva 《Journal of Applied Mathematics and Physics》 2023年第10期3009-3029,共21页
The article puts forward a hypothesis about the possibility of the existence of our Universe inside a supermassive black hole, analyzes the basic assumptions and verifiable physical consequences. The transformation of... The article puts forward a hypothesis about the possibility of the existence of our Universe inside a supermassive black hole, analyzes the basic assumptions and verifiable physical consequences. The transformation of the Primary Particles obtained from the decay of Borromeo rings into binary and ternary structures is considered separately, taking into account how the percentages between Dark Matter, Dark Energy and Baryonic matter are formed. A system of kinetic equations has been compiled, which makes it possible to develop a theoretical approach to obtain these values depending on the geometric and physical characteristics of interacting particles. The possibility and necessity of the existence of a Primary Relic of Primary Particles are substantiated. The nature of the voids and the analytical solution of the Einstein equations obtained from the generalized Papapetrou solution, which leads to the existence of strings with an arbitrary distribution of matter along the string and with lengths comparable to the size of the Universe, are considered. In the case of a string of finite size and constant density, this solution leads to the well-known Weyl solution. An assumption is put forward about the existence of an Einstein-Rosen type transition, when the dimensions of the white and black holes at the ends of this transition have different dimensions. 展开更多
关键词 black Hole White Hole Einstein-Rosen Bridge Primary Relic Voids Strings Dark Matter Dark Energy Borromeo Rings Dark Stars Generalized Papapetrou Solution Weyl Solution
下载PDF
Sedimentary Environment and Mineralization of the Black Shale Polymetallic Layer in the Early Cambrian,SW China:Constraints from in situ LA-ICP-MS Analysis of Pyrite
4
作者 YANG Zhen FU Yong +2 位作者 LI Chao CAI Xi GUO Chuan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2024年第2期416-429,共14页
A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differ... A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of pyrite.The results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan profile.The isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional environments.The sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from seawater.Overall,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid. 展开更多
关键词 sedimentary environment black shale polymetallic layer PYRITE early Cambrian
下载PDF
Polyphenol components in black chokeberry(Aronia melanocarpa)as clinically proven diseases control factors——an overview
5
作者 Ningxuan Gao Chi Shu +10 位作者 Yuehua Wang Jinlong Tian Yuxi Lang Chenyu Jin Xingyue Cui Hanqian Jiang Shi’an Liu Zhiying Li Wei Chen Hao Xu Bin Li 《Food Science and Human Wellness》 SCIE CSCD 2024年第3期1152-1167,共16页
The black chokeberry is rich in polyphenols,including flavonoids with anthocyanins,flavanols and lavonols as the main components and a variety of phenolic acids represented by chlorogenic acid.Because of these polyphe... The black chokeberry is rich in polyphenols,including flavonoids with anthocyanins,flavanols and lavonols as the main components and a variety of phenolic acids represented by chlorogenic acid.Because of these polyphenols,black chokeberry has the effect of preventing and adjuvant therapy diseases.This study summarized the current research results on the types and contents of functional components in black chokeberry,and analyzed their digestion,absorption and metabolism in human body.On this basis,the disease control functions that have been proved effective in clinical research were reviewed and analyzed.These studies showed that black chokeberry have good prevention and adjuvant therapy effects on hyperlipidemia,hypertension,diabetes and inflammation.Because there are different functional components in black chokeberry,its prevention and treatment of the same disease can come from multiple pathways,which provides a more reliable effectiveness for the disease control of different populations. 展开更多
关键词 black chokeberry HYPERLIPIDEMIA HYPERTENSION DIABETES Inflammation
下载PDF
Covalently Bonded Ni Sites in Black Phosphorene with Electron Redistribution for Efficient Metal‑Lightweighted Water Electrolysis
6
作者 Wenfang Zhai Ya Chen +5 位作者 Yaoda Liu Yuanyuan Ma Paranthaman Vijayakumar Yuanbin Qin Yongquan Qu Zhengfei Dai 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第6期233-245,共13页
The metal-lightweighted electrocatalysts for water splitting are highly desired for sustainable and economic hydrogen energy deployments,but challengeable.In this work,a low-content Ni-functionalized approach triggers... The metal-lightweighted electrocatalysts for water splitting are highly desired for sustainable and economic hydrogen energy deployments,but challengeable.In this work,a low-content Ni-functionalized approach triggers the high capability of black phosphorene(BP)with hydrogen and oxygen evolution reaction(HER/OER)bifunctionality.Through a facile in situ electro-exfoliation route,the ionized Ni sites are covalently functionalized in BP nanosheets with electron redistribution and controllable metal contents.It is found that the as-fabricated Ni-BP electrocatalysts can drive the water splitting with much enhanced HER and OER activities.In 1.0 M KOH electrolyte,the optimized 1.5 wt%Nifunctionalized BP nanosheets have readily achieved low overpotentials of 136 mV for HER and 230 mV for OER at 10 mA cm^(−2).Moreover,the covalently bonding between Ni and P has also strengthened the catalytic stability of the Ni-functionalized BP electrocatalyst,stably delivering the overall water splitting for 50 h at 20 mA cm^(−2).Theoretical calculations have revealed that Ni–P covalent binding can regulate the electronic structure and optimize the reaction energy barrier to improve the catalytic activity effectively.This work confirms that Ni-functionalized BP is a suitable candidate for electrocatalytic overall water splitting,and provides effective strategies for constructing metal-lightweighted economic electrocatalysts. 展开更多
关键词 black phosphorus Water electrolysis ELECTROCATALYST Electron redistribution Covalent functionalization
下载PDF
Ash removal from inferior coal via ammonium fluoride roasting and simultaneous yield of white carbon black
7
作者 Xuqin Duan Shuaiyu Lu +3 位作者 Yuxiao Fu Jiazhe Zhang Tong Liu Jian Ma 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期261-279,共19页
The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial produc... The quality upgrading and deashing of inferior coal by chemical method still faces great challenges.The dangers of strong acid,strong alkali,waste water and exhaust gas as well as high cost limit its industrial production.This paper systematically investigates the ash reduction and desilicification of two typical inferior coal utilizing ammonium fluoride roasting method.Under the optimal conditions,for fat coal and gas coal,the deashing rates are 69.02%and 54.13%,and the desilicification rates are 92.64%and 90.27%,respectively.The molar dosage of ammonium fluoride remains consistent for both coals;however,the gas coal,characterized by a lower ash and silica content(less than half that of the fat coal),achieves optimum deashing effect at a reduced time and temperature.The majority of silicon in coal transforms into gaseous ammonium fluorosilicate,subsequently preparing nanoscale amorphous silica with a purity of 99.90%through ammonia precipitation.Most of the fluorine in deashed coal are assigned in inorganic minerals,suggesting the possibility of further fluorine and ash removal via flotation.This research provides a green and facile route to deash inferior coal and produce nano-scale white carbon black simultaneously. 展开更多
关键词 Inferior coal Deashing treatment Silicon recycling Ammonium fluoride roasting White carbon black
下载PDF
Thermodynamics in a quantum corrected Reissner-Nordstr?m-AdS black hole and its GUP-corrections
8
作者 宋建君 刘成周 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期345-353,共9页
We calculate the thermodynamic quantities in the quantum corrected Reissner-Nordstr?m-AdS(RN-AdS)black hole,and examine their quantum corrections.By analyzing the mass and heat capacity,we give the critical state and ... We calculate the thermodynamic quantities in the quantum corrected Reissner-Nordstr?m-AdS(RN-AdS)black hole,and examine their quantum corrections.By analyzing the mass and heat capacity,we give the critical state and the remnant state,respectively,and discuss their consistency.Then,we investigate the quantum tunneling from the event horizon of massless scalar particle by using the null geodesic method,and charged massive boson W^(±)and fermions by using the Hamilton-Jacob method.It is shown that the same Hawking temperature can be obtained from these tunneling processes of different particles and methods.Next,by using the generalized uncertainty principle(GUP),we study the quantum corrections to the tunneling and the temperature.Then the logarithmic correction to the black hole entropy is obtained. 展开更多
关键词 black hole thermodynamics quantum corrections quantum tunneling generalized uncertainty principle
下载PDF
View of thermodynamic phase transition of the charged Gauss-Bonnet AdS black hole via the shadow
9
作者 何柯腱 郭森 +1 位作者 罗智 李国平 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期355-362,共8页
We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),a... We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior. 展开更多
关键词 Gauss-Bonnet AdS black hole thermodynamic SHADOW
下载PDF
Triple points and phase transitions of D-dimensional dyonic Ad S black holes with quasitopological electromagnetism in Einstein–Gauss–Bonnet gravity
10
作者 牟平辉 蒋青权 +1 位作者 何柯腱 李国平 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期272-287,共16页
By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnet... By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet(EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals(vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions.Specifically, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic Ad S BHs with quasitopological electromagnetism in Einstein–Born–Infeld(EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D105 104048(2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic Ad S BHs with quasitopological electromagnetism in EGB gravity. 展开更多
关键词 AdS black hole phase transition triple point
下载PDF
Timing and Spectral Analysis of the Black Hole X-Ray Binary MAXI J1803-298 with Insight-HXMT Data
11
作者 Ying-Chen Xu Jin-Lu Qu +6 位作者 MMéndez Rui-Can Ma Long Ji Liang Zhang Yue Huang Qing-Cui Bu Li-Ming Song 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期209-224,共16页
We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft state.Wi... We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft state.Within the Insight-HXMT data set,compared to the previous work,we identify a more prolonged presence of typeC quasi-periodic oscillations(QPOs)with centroid frequencies ranging from~0.16 to 6.3 Hz,which present correlations with the hardness ratio and the photon index of the Comptonized component.For QPO frequencies less than~2 Hz,the QPO phase lags are hard(photons of 10–19 keV arrive later than those of 1–4 keV),while at higher frequencies,the lags become soft at and above~4 Hz.Furthermore,the spectra in all Insight-HXMT observations consist of a multi-color blackbody component and a Comptonized component,as commonly observed in classical black hole X-ray binaries.We analyze state transitions and the evolution of accretion geometry in this work.The fitted inner disk radius increases abnormally during the low hard state,hypothesized to result from the corona condensing onto the inner disk.Additionally,two significant drops in flux are observed during the soft intermediate state,maybe implying changes in the corona/jet and the disk,respectively. 展开更多
关键词 X-rays:binaries ACCRETION accretion disks stars:black holes
下载PDF
Analysis of flavor and widely metabolomics differences in black sesame before and after processing
12
作者 Yini Yang Linhai Wang +3 位作者 Yunhai Wang Yuting An Qi Zhou Xia Xiang 《Oil Crop Science》 CSCD 2024年第1期38-45,共8页
The objective of this study was to determine the differences of aroma and taste in three black sesame originsbefore and after processing via flavor and widely metabolomics.By analyzing the sensory characteristics and ... The objective of this study was to determine the differences of aroma and taste in three black sesame originsbefore and after processing via flavor and widely metabolomics.By analyzing the sensory characteristics and metabolites of raw and treated black sesame from China,Vietnam,and Myanmar,treated Chinese sesame have the most significant change in hardness after thermal processing,low viscosity and was easy to chew.The electronic nose could distinguish between raw and treated sesame due to the aroma distribution.The reason of treated sesame from China was“fragrant”is due to the highest content(2545.50μg/kg)of total pyrazines including 2,5-dimethylpyrazine,2-ethyl-5-methylpyrazine,2,3,5-trimethylpyrazine,3-ethyl-2,5-dimethylpyrazine.933 metabolites were detected via a wide targeted metabolomics in the taste of raw and treated sesame.Based on the analysis of metabolites related to bitterness,145 substances were selected.The main bitter contributors may be amino acids,dipeptides and organic acids. 展开更多
关键词 Flavoromics Metabolomics black sesame AROMA TASTE Distribution
下载PDF
Genome-Wide Characterization of the Hyaluronidase Gene Family and Their Potential Roles in Viviparous Black Rockfish(Sebastes schlegeli)
13
作者 LIU Zhiying NIU Jingning +4 位作者 ZHAO Xi LIU Huaxiang LI Zibin HE Yan QI Jie 《Journal of Ocean University of China》 CAS CSCD 2024年第2期487-498,共12页
Black rockfish(Sebastes schlegelii)has evolved viviparous reproduction mode.Different from the oviparous fishes,the spermatozoa of black rockfish are stored on the surface of ovarian follicle for over four months unti... Black rockfish(Sebastes schlegelii)has evolved viviparous reproduction mode.Different from the oviparous fishes,the spermatozoa of black rockfish are stored on the surface of ovarian follicle for over four months until the egg mature in ovary,while the adaptive evolution of fertilization-related genes remains to be studied.In the present study,based on the genome and transcriptome information of black rockfish,a total of 10 hyaluronidase genes were identified by phylogenetic and sequence analyses,including hyal1,hyal2,hyal3,hyal4,hyal6 and spam1a,spam1b,spam1c and spam1d.The spam1 subfamilies,including spam1a,spam1b,spam1c and spam1d,were significantly expanded compared to other species.The adaptive evolution of hyaluronidase was further investigated by selection pressure analysis of branch model and branch site model.The results showed that only spam1 subfamily was positively selected with a large number of positive selection sites,and the evolution rate was significantly higher thanthose of other teleosts.Two positively selected sites,LYS-171 and GLY-164,were located in the neutral hyaluronidase activity domain,which was pivotal for SPAM1 to participate in enzymatic hydrolysis of the extracellular hyaluronic acid matrix and mediate acrosome reaction in mammals.Furthermore,spam1 was mainly expressed in spermatocytes,secondary spermatocytes,and spermatids of testis,whereas it was not found in metamorphic sperm and mature sperm based on the spatiotemporal expression analysis.All results indicated that spam1 might originate from the testis and might be an adaptation of viviparous trait in black rockfish. 展开更多
关键词 adaptation of viviparous black rockfish(Sebastes schlegelii) HYALURONIDASE selective pressure analysis
下载PDF
Vibration of black phosphorus nanotubes via orthotropic cylindrical shell model
14
作者 Minglei He Lifeng Wang 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第3期166-173,共8页
Black phosphorus nanotubes(BPNTs)may have good properties and potential applications.Determining thevibration property of BPNTs is essential for gaining insight into the mechanical behaviour of BPNTs and designingopti... Black phosphorus nanotubes(BPNTs)may have good properties and potential applications.Determining thevibration property of BPNTs is essential for gaining insight into the mechanical behaviour of BPNTs and designingoptimized nanodevices.In this paper,the mechanical behaviour and vibration property of BPNTs are studied viaorthotropic cylindrical shell model and molecular dynamics(MD)simulation.The vibration frequencies of twochiral BPNTs are analysed systematically.According to the results of MD calculations,it is revealed that thenatural frequencies of two BPNTs with approximately equal sizes are unequal at each order,and that the naturalfrequencies of armchair BPNTs are higher than those of zigzag BPNTs.In addition,an armchair BPNTs witha stable structure is considered as the object of research,and the vibration frequencies of BPNTs of differentsizes are analysed.When comparing the MD results,it is found that both the isotropic cylindrical shell modeland orthotropic cylindrical shell model can better predict the thermal vibration of the lower order modes of thelonger BPNTs better.However,for the vibration of shorter and thinner BPNTs,the prediction of the orthotropiccylindrical shell model is obviously superior to the isotropic shell model,thereby further proving the validity ofthe shell model that considers orthotropic for BPNTs. 展开更多
关键词 Orthotropic cylindrical shell Molecular dynamics simulation black phosphorus nanotube VIBRATION
下载PDF
Secure and Reliable Routing in the Internet of Vehicles Network:AODV-RL with BHA Attack Defense
15
作者 Nadeem Ahmed Khalid Mohammadani +3 位作者 Ali Kashif Bashir Marwan Omar Angel Jones Fayaz Hassan 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第4期633-659,共27页
Wireless technology is transforming the future of transportation through the development of the Internet of Vehicles(IoV).However,intricate security challenges are intertwinedwith technological progress:Vehicular ad h... Wireless technology is transforming the future of transportation through the development of the Internet of Vehicles(IoV).However,intricate security challenges are intertwinedwith technological progress:Vehicular ad hoc Networks(VANETs),a core component of IoV,face security issues,particularly the Black Hole Attack(BHA).This malicious attack disrupts the seamless flow of data and threatens the network’s overall reliability;also,BHA strategically disrupts communication pathways by dropping data packets from legitimate nodes altogether.Recognizing the importance of this challenge,we have introduced a new solution called ad hoc On-Demand Distance Vector-Reputation-based mechanism Local Outlier Factor(AODV-RL).The significance of AODVRL lies in its unique approach:it verifies and confirms the trustworthiness of network components,providing robust protection against BHA.An additional safety layer is established by implementing the Local Outlier Factor(LOF),which detects and addresses abnormal network behaviors.Rigorous testing of our solution has revealed its remarkable ability to enhance communication in VANETs.Specifically,Our experimental results achieve message delivery ratios of up to 94.25%andminimal packet loss ratios of just 0.297%.Based on our experimental results,the proposedmechanismsignificantly improves VANET communication reliability and security.These results promise a more secure and dependable future for IoV,capable of transforming transportation safety and efficiency. 展开更多
关键词 black hole attack IoV vehicular ad hoc network AODV routing protocol
下载PDF
Modified Black Widow Optimization-Based Enhanced Threshold Energy Detection Technique for Spectrum Sensing in Cognitive Radio Networks
16
作者 R.Saravanan R.Muthaiah A.Rajesh 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第3期2339-2356,共18页
This study develops an Enhanced Threshold Based Energy Detection approach(ETBED)for spectrum sensing in a cognitive radio network.The threshold identification method is implemented in the received signal at the second... This study develops an Enhanced Threshold Based Energy Detection approach(ETBED)for spectrum sensing in a cognitive radio network.The threshold identification method is implemented in the received signal at the secondary user based on the square law.The proposed method is implemented with the signal transmission of multiple outputs-orthogonal frequency division multiplexing.Additionally,the proposed method is considered the dynamic detection threshold adjustments and energy identification spectrum sensing technique in cognitive radio systems.In the dynamic threshold,the signal ratio-based threshold is fixed.The threshold is computed by considering the Modified Black Widow Optimization Algorithm(MBWO).So,the proposed methodology is a combination of dynamic threshold detection and MBWO.The general threshold-based detection technique has different limitations such as the inability optimal signal threshold for determining the presence of the primary user signal.These limitations undermine the sensing accuracy of the energy identification technique.Hence,the ETBED technique is developed to enhance the energy efficiency of cognitive radio networks.The projected approach is executed and analyzed with performance and comparison analysis.The proposed method is contrasted with the conventional techniques of theWhale Optimization Algorithm(WOA)and GreyWolf Optimization(GWO).It indicated superior results,achieving a high average throughput of 2.2 Mbps and an energy efficiency of 3.8,outperforming conventional techniques. 展开更多
关键词 Cognitive radio network spectrum sensing noise uncertainty modified black widow optimization algorithm energy detection technique
下载PDF
Spatio-temporal Evaluation of Multi-scale Cultivated Land System Resilience in Black Soil Region from 2000 to 2019:A Case Study of Liaoning Province,Northeast China
17
作者 WANG Yue JIANG Yuting ZHU Guoxu 《Chinese Geographical Science》 SCIE CSCD 2024年第1期168-180,共13页
It is of great significance to systematically analyze the cultivated land system resilience(CLSR) for the black soil protection and national food security.The CLSR is impacted by planting structure adjustment and cult... It is of great significance to systematically analyze the cultivated land system resilience(CLSR) for the black soil protection and national food security.The CLSR is impacted by planting structure adjustment and cultivated land quality decline,posing major hidden dangers to food security.It is urgent to evaluate the CLSR at multiple spatio-temporal scales.This study took Liaoning Province in the black soil region of Northeast China as an example.Based on the resilience theory,this study constructed the CLSR evaluation system from the input-feedback perspective at the provincial-scale and the city-scale,and used the rank-sum ratio comprehensive evaluation method(RSR) to analyze the key influencing factors of CLSR in Liaoning Province and its 14 cities from 2000 to 2019.The results showed that:1) the time series changes of CLSR at the provincial-scale and the city-scale in Liaoning Province were similar,both showing an increasing trend.2) The CLSR in Liaoning Province presented a spatial pattern of ‘high in the west and low in the east’ at the city-scale.3) There were seven and six main influencing factors of CLSR at the provincial-scale and the city-scale,respectively.In addition to the net income per capita of rural households,other influencing factors of CLSR were different at the provincial-scale and the city-scale.The feedback factors were dominant at the provincial-scale,and the input factors and feedback factors were dominant at the city-scale.The results could provide a reference for the utilization of black soil and draw on the experience of regional agricultural planning and adjustment. 展开更多
关键词 cultivated land system resilience(CLSR) rank-sum ratio comprehensive evaluation(RSR) multi-scales influencing factors black soil region Liaoning Province China
下载PDF
Assessing the Efficacy of Lemongrass (Cymbopogon citratus) and Sambong (Blumea balsamifera) Extracts in Combating Black Pod Disease: Sustainable Solutions for Controlling Phytophthora megakarya in Cameroon’s Cocoa Plantations
18
作者 Gertrude Membang James Michel Tchotet Tchoumi +5 位作者 Godswill Ntsomboh Ntsefong Emmanuel Yvan Mba Ela Sylvere Landry Lontsi Dida Ludovic Tchuenkam Tsango Pascal Loïc Ekango Mbondjo Fritz Oben Tabi 《American Journal of Plant Sciences》 CAS 2024年第7期519-537,共19页
The use of plant extracts as antifungal agents is gaining increasing attention, particularly for the control of black pod disease in cocoa. Despite extensive research, current strategies haven’t been entirely effecti... The use of plant extracts as antifungal agents is gaining increasing attention, particularly for the control of black pod disease in cocoa. Despite extensive research, current strategies haven’t been entirely effective. This study evaluated the effectiveness of Cymbopogon citratus and Blumea balsamifora leaf extracts, both individually and in combination, against Phytophthora megakarya. We assessed the efficacy of the most promising combination (75% B. balsamifera, 25% C. citratus) after storage at room temperature for up to 9 days. Agar microdilution and in vivo bioassays were conducted to determine antifungal susceptibility and effectiveness. Blumea extract exhibited the highest overall inhibitory activity, with the lowest minimum inhibitory concentration (117 µl mL−1) while C. citratus had a narrower range of MIC (146 to 233 µl mL−1). The combination of C. citratus and B. balsamifera demonstrated a synergistic effect against P. megakarya, achieving growth inhibition on V8 media (92.72 ± 4.20% to 100%) and on artificially infected detached pod cortex (92.24 ± 4.53% to 98.75 ± 1.25%), which was not significantly different from the positive control (Ridomil). Furthermore, this combination maintained its effectiveness for up to 9 days at room temperature. These findings suggest that combining plant extracts can enhance their antifungal properties. 展开更多
关键词 Plant Extracts Antifungal Agents Synergistic Effect black Pod Disease Cocoa
下载PDF
A progress review of black carbon deposition on Arctic snow and ice and its impact on climate change
19
作者 ZHANG Zilu ZHOU Libo ZHANG Meigen 《Advances in Polar Science》 CSCD 2024年第2期178-191,共14页
The rapid warming of the Arctic,accompanied by glacier and sea ice melt,has significant consequences for the Earth’s climate,ecosystems,and economy.Black carbon(BC)deposition on snow and ice can trigger a significant... The rapid warming of the Arctic,accompanied by glacier and sea ice melt,has significant consequences for the Earth’s climate,ecosystems,and economy.Black carbon(BC)deposition on snow and ice can trigger a significant reduction in snow albedo and accelerate melting of snow and ice in the Arctic.By reviewing the published literatures over the past decades,this work provides an overview of the progress in both the measurement and modeling of BC deposition and its impact on Arctic climate change.In summary,the maximum value of BC deposition appears in the western Russian Arctic(26 ng·g^(–1)),and the minimum value appears in Greenland(3 ng·g^(–1)).BC records in the Arctic ice core already peaked in 1920s and 1970s,and shows a regional difference between Greenland and Canadian Arctic.The different temporal variations of Arctic BC ice core records in different regions are closely related to the large variability of BC emissions and transportation processes across the Arctic region.Model simulations usually underestimate the concentration of BC in snow and ice by 2–3 times,and cannot accurately reflect the seasonal and regional changes in BC deposition.Wet deposition is the main removal mechanism of BC in the Arctic,and observations show different seasonal variations in BC wet deposition in Ny-Ålesund and Barrow.This discrepancy may result from varying contributions of anthropogenic and biomass burning(BB)emissions,given the strong influence by BC from BB emissions at Barrow.Arctic BC deposition significantly influences regional climate change in the Arctic,increasing fire activities in the Arctic have made BB source of Arctic BC more crucial.On average,BC in Arctic snow and ice causes an increase of+0.17 W·m^(–2)in radiative forcing and 8 Gt·a^(–1)in runoff in Greenland.As stressed in the latest Arctic Monitoring and Assessment Programme report,reliable source information and long-term and high-resolution observations on Arctic BC deposition will be crucial for a more comprehensive understanding and a better mitigation strategy of Arctic BC.In the future,it is necessary to collect more observations on BC deposition and the corresponding physical processes(e.g.,snow/ice melting,surface energy balance)in the Arctic to provide reliable data for understanding and clarifying the mechanism of the climatic impacts of BC deposition on Arctic snow and ice. 展开更多
关键词 Arctic climate black carbon ALBEDO SNOW DEPOSITION
下载PDF
Formation,evolution,reconstruction of black shales and their influence on shale oil and gas resource
20
作者 Shi-zhen Li Qiu-chen Xu +11 位作者 Mu Liu Guo-heng Liu Yi-fan Li Wen-yang Wang Xiao-guang Yang Wei-bin Liu Yan-fei An Peng Sun Tao Liu Jiang-hui Ding Qian-chao Li Chao-gang Fang 《China Geology》 CAS CSCD 2024年第3期551-585,共35页
Black shales are important products of material cycling and energy exchange among the lithosphere,atmosphere,hydrosphere,and biosphere.They are widely distributed throughout geological history and provide essential en... Black shales are important products of material cycling and energy exchange among the lithosphere,atmosphere,hydrosphere,and biosphere.They are widely distributed throughout geological history and provide essential energy and mineral resources for the development of human society.They also record the evolution process of the earth and improve the understanding of the earth.This review focuses on the diagenesis and formation mechanisms of black shales sedimentation,composition,evolution,and reconstruction,which have had a significant impact on the formation and enrichment of shale oil and gas.In terms of sedimentary environment,black shales can be classified into three types:Marine,terrestrial,and marine-terrestrial transitional facies.The formation processes include mechanisms such as eolian input,hypopycnal flow,gravity-driven and offshore bottom currents.From a geological perspective,the formation of black shales is often closely related to global or regional major geological events.The enrichment of organic matter is generally the result of the interaction and coupling of several factors such as primary productivity,water redox condition,and sedimentation rate.In terms of evolution,black shales have undergone diagenetic evolution of inorganic minerals,thermal evolution of organic matter and hydrocarbon generation,interactions between organic matter and inorganic minerals,and pore evolution.In terms of reconstruction,the effects of fold deformation,uplift and erosion,and fracturing have changed the stress state of black shale reservoirs,thereby having a significant impact on the pore structure.Fluid activity promotes the formation of veins,and have changed the material composition,stress structure,and reservoir properties of black shales.Regarding resource effects,the deposition of black shales is fundamental for shale oil and gas resources,the evolution of black shales promotes the shale oil and gas formation and storage,and the reconstruction of black shales would have caused the heterogeneous distribution of oil and gas in shales.Exploring the formation mechanisms and interactions of black shales at different scales is a key to in-depth research on shale formation and evolution,as well as the key to revealing the mechanism controlling shale oil and gas accumulation.The present records can reveal how these processes worked in geological history,and improve our understanding of the coupling mechanisms among regional geological events,black shales evolution,and shale oil and gas formation and enrichment. 展开更多
关键词 black shales Shale oil and gas Resource effects Sedimentary environment Sedimentary process Organic matter accumulation Diagenetic evolution Thermal evolution Organic matter and inorganic minerals Tectonic reconstruction Oil and gas exploration engineering VEINS Fluid activity
下载PDF
上一页 1 2 143 下一页 到第
使用帮助 返回顶部