Next generation wireless communication is based on a global system of fixed and wireless mobile services thatare transportable across different network back-bones,network service providers and network geographical bou...Next generation wireless communication is based on a global system of fixed and wireless mobile services thatare transportable across different network back-bones,network service providers and network geographical boundaries.This paper presents an approach to investigate the effects of soft handover and perfect power control on the forward link ina DS-CDMA cellular system.Especially,the relationships between the size ofhandover zone and the capacity gain are e-valuated under the log-normal shadow channel.Then the optimization of maximum forward capacity is very necessary tobe done with the maximum size of soft handover zone to the various system characteristics.展开更多
Before joining the Beijing Dragon Shadow Puppetry Art Theatre,this group of young people rarely had the chance to meet people like themselves,lacked friends,faced obstacles at work,and felt alienated from society.Now,...Before joining the Beijing Dragon Shadow Puppetry Art Theatre,this group of young people rarely had the chance to meet people like themselves,lacked friends,faced obstacles at work,and felt alienated from society.Now,they have gained appreciation,recognition,confidence,friendships,and love.展开更多
Modeling time headways between vehicles has attracted increasing interest in the traffic flow research field recently, because the corresponding statistics help to reveal the intrinsic interactions governing the vehic...Modeling time headways between vehicles has attracted increasing interest in the traffic flow research field recently, because the corresponding statistics help to reveal the intrinsic interactions governing the vehicle dynamics. However, most previous micro-simulation models cannot yield the observed log-normal distributed headways. This paper designs a new car-following model inspired by the Galton board to reproduce the observed time-headway distributions as well as the complex traffic phenomena. The consistency between the empirical data and the simulation results indicates that this new car-following model provides a reasonable description of the car-following behaviours.展开更多
In this paper, we propose a log-normal linear model whose errors are first-order correlated, and suggest a two-stage method for the efficient estimation of the conditional mean of the response variable at the original...In this paper, we propose a log-normal linear model whose errors are first-order correlated, and suggest a two-stage method for the efficient estimation of the conditional mean of the response variable at the original scale. We obtain two estimators which minimize the asymptotic mean squared error （MM） and the asymptotic bias （MB）, respectively. Both the estimators are very easy to implement, and simulation studies show that they are perform better.展开更多
Medical research data are often skewed and heteroscedastic. It has therefore become practice to log-transform data in regression analysis, in order to stabilize the variance. Regression analysis on log-transformed dat...Medical research data are often skewed and heteroscedastic. It has therefore become practice to log-transform data in regression analysis, in order to stabilize the variance. Regression analysis on log-transformed data estimates the relative effect, whereas it is often the absolute effect of a predictor that is of interest. We propose a maximum likelihood (ML)-based approach to estimate a linear regression model on log-normal, heteroscedastic data. The new method was evaluated with a large simulation study. Log-normal observations were generated according to the simulation models and parameters were estimated using the new ML method, ordinary least-squares regression (LS) and weighed least-squares regression (WLS). All three methods produced unbiased estimates of parameters and expected response, and ML and WLS yielded smaller standard errors than LS. The approximate normality of the Wald statistic, used for tests of the ML estimates, in most situations produced correct type I error risk. Only ML and WLS produced correct confidence intervals for the estimated expected value. ML had the highest power for tests regarding β1.展开更多
We have observed weather clutter containing targets (ships) using an S-band radar with a frequency 3.05 GHz, a beam width 1.8°, and a pulsewidth 0.5 μs. To investigate the weather clutter amplitude statistics, w...We have observed weather clutter containing targets (ships) using an S-band radar with a frequency 3.05 GHz, a beam width 1.8°, and a pulsewidth 0.5 μs. To investigate the weather clutter amplitude statistics, we introduce the Akaike Information Criterion (AIC). We have found that the weather clutter amplitudes obey the log-normal, Weibull, and log-Weibull distributions with the shape parameters of 0.308 to 0.470, 4.42 to 4.51, and 15.91 to 16.44, respectively, for small data within the beam width of an antenna. We have proposed the log-normal/CFAR circuit modified a Cell-Averaging (CA) LOG/CFAR circuit. It is found that weather clutter is suppressed with improvement of 51.58 dB by log-normal/CFAR. As a result, we have showed that weather clutter observed by S-band radar does not obey the Rayleigh distribution and our log-normal/CFAR circuit has an effect on suppression of clutter and detection of target, while conventional LOG/CFAR circuit does not. In addition, if our circuit can be realized, we will have an advantage economically.展开更多
As Artificial Intelligence(AI)is moving fast from Large Language Models(LLMs)to AI Agents and Agentic Intelligence,the need to incorporate new AI into Decision Intelligence(DI)is becoming more and more urgent for both...As Artificial Intelligence(AI)is moving fast from Large Language Models(LLMs)to AI Agents and Agentic Intelligence,the need to incorporate new AI into Decision Intelligence(DI)is becoming more and more urgent for both practical and theoretic reasons:both decision and process complexities would be significantly increased due to the use of advanced AI tools and agents,and both traditional and recent thinking must be rethought and reconstructed accordingly.Our perspective would like to address this important issue based on some historical milestone developments in Computer-Aided Software Engineering(CASE)and recent efforts in digital theatrical technology[1].展开更多
Digital twin(DT)technology has been utilised in many applications including electric vehicles(EVs).A DT is a virtual representation of a physical object,enabled through real-time data integration,simulation,and optimi...Digital twin(DT)technology has been utilised in many applications including electric vehicles(EVs).A DT is a virtual representation of a physical object,enabled through real-time data integration,simulation,and optimisation tools.Unlike conventional simulations,which are typically offline and lack real-time interaction,a DT continuously synchronises with the physical system,enabling dynamic performance monitoring and predictive an-alytics.Achieving a full DT involves progressive stages,with the digital shadow(DS)being the final step before realising a bidirectional DT.Building a DS provides a scalable real-time performance monitoring and fault detection framework,enabling proactive decision-making in EV operations.This study introduces a DS system specifically designed to monitor the performance of a permanent magnet synchronous motor(PMSM)drive system in EVs,marking a critical phase towards a complete DT.The methodology for creating the DS is detailed,including the establishment of a compre-hensive test bench for the EV powertrain as the physical reference model.The mathe-matical model of the EV-PMSM was formulated,and an advanced estimation model utilising the extended Kalman filter(EKF)was implemented.MATLAB/Simulink was employed to develop the motor’s digital model.Real-time data acquisition from the physical model was facilitated through a data acquisition system(DAS)equipped with a controller area network(CAN)communication interface.The digital model underwent thorough validation against sensory data collected from the test bench.The motor digital model was deployed to a DS framework enabled through real-time data flow from the actual EV during real-world driving conditions.The results demonstrated a high accuracy of 97%between the DS predictions and the corresponding EV data,confirming the DS’s reliability.These findings pave the way for future advancements,including bidirectional interaction and the realisation of a full DT.展开更多
In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the...In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.展开更多
Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on th...Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on this paradigm,recent developments have introduced a novel class of black holes within the VEG framework,revealing intriguing connections between apparent dark matter effects and the distribution of baryonic matter.In this study,we delve into the observational signatures of a Simpson–Visser(SV)Minkowski core regular black hole in VEG,focusing on its shadow images and intensity profiles.Our analysis highlights the profound influence of model parameters,including A(governing baryonic matter distribution),B(strength of interaction between apparent dark matter and baryonic matter),and n(characterizing diverse spacetime geometries),on the effective potential and observable properties.Notably,we find that the modifications introduced by these parameters lead to distinct changes in the black hole's shadow size and intensity distribution.Comparing our results to the Reissner–Nordström(RN)black hole,we uncover a striking reduction in the apparent shadow size and an enhancement in intensity for the SV solution in VEG.展开更多
In this paper,we investigate the optical properties of a non-rotating charged black hole(BH)in the Einstein-Maxwell-scalar(EMS)theory,together with a plasma medium.We first consider the photon sphere and shadow radius...In this paper,we investigate the optical properties of a non-rotating charged black hole(BH)in the Einstein-Maxwell-scalar(EMS)theory,together with a plasma medium.We first consider the photon sphere and shadow radius under the impact of the plasma medium existing in the environment surrounding the BH in the EMS theory.We show that the radius of the photon sphere and the BH shadow decrease under the influence of the parameterβ.We further study gravitational weak lensing in detail by adapting general methods and derive the light ray's deflection angle around the BH together with the plasma environment.It is found that for uniform plasma,the deflection angle increases with the rise of the plasma parameter,whereas it decreases with the increase of the plasma parameter for non-uniform plasma.Besides,we also study the magnification of image brightness.展开更多
Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,i...Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.展开更多
The photon region surrounding a black hole is crucial for distant observers to receive the emitted spectrum from its vicinity.This paper investigates the optical features of a regular spinning antide Sitter(AdS)black ...The photon region surrounding a black hole is crucial for distant observers to receive the emitted spectrum from its vicinity.This paper investigates the optical features of a regular spinning antide Sitter(AdS)black hole.These kinds of black holes hold deviation parameter k,and the cosmological constant A including their mass M and spin a.The cosmological parameter depends on the curvature radius by A=-3/l~2.We investigate the structure of geodesics for unstable circular orbits of photons as observed by an observer at specific Boyer-Lindquist coordinates(r_(O),v_(O))in the region between the outer and cosmological horizon,so-called the domain of outer communication.Our investigations include the analysis of three observables from its shadow plot:the black hole shadow radius(R_(s)),the distortion of the black hole(δ_(s)),and shadow area A.With the help of these observables,we calculate the angular diameter of the apparent size of the shadow.The shadows cast by spinning regular spacetimes are smaller compared to those produced by rotating black holes in both general relativity and regular spacetimes.We also calculate the rate at which energy is emitted from the black hole.展开更多
The marginal abatement cost(MAC)of CO_(2)emissions is one of the most critical indicators used to assess energy conservation and emission reduction.Although extensively measured,few studies have incorporated the influ...The marginal abatement cost(MAC)of CO_(2)emissions is one of the most critical indicators used to assess energy conservation and emission reduction.Although extensively measured,few studies have incorporated the influence of policy constraints when evaluating MAC.To address this gap,this paper proposes a nonparametric directional distance function approach under policy regulations to estimate the CO_(2)shadow price in the construction industry across 30 Chinese provinces from 2010 to 2017.Based on this enhanced method,four key findings emerge:①the annual CO_(2)shadow price exhibits an overall upward trend during the observation period;②regional shadow prices display marked variation across provinces;③regional heterogeneity in shadow prices has increased steadily over time;and④both urbanization rate and energy consumption per unit of gross domestic product are significantly negatively correlated with the CO_(2)shadow price.Finally,the paper offers several policy recommendations for CO_(2)emissions reduction in the Chinese construction industry at the national,industry,and enterprise levels.展开更多
文摘Next generation wireless communication is based on a global system of fixed and wireless mobile services thatare transportable across different network back-bones,network service providers and network geographical boundaries.This paper presents an approach to investigate the effects of soft handover and perfect power control on the forward link ina DS-CDMA cellular system.Especially,the relationships between the size ofhandover zone and the capacity gain are e-valuated under the log-normal shadow channel.Then the optimization of maximum forward capacity is very necessary tobe done with the maximum size of soft handover zone to the various system characteristics.
文摘Before joining the Beijing Dragon Shadow Puppetry Art Theatre,this group of young people rarely had the chance to meet people like themselves,lacked friends,faced obstacles at work,and felt alienated from society.Now,they have gained appreciation,recognition,confidence,friendships,and love.
基金supported partly by the National Basic Research Program of China (Grant No. 2006CB705506)the National Hi-Tech Research and Development Program of China (Grant Nos. 2006AA11Z215 and 2007AA11Z222)the National Natural Science Foundation of China (Grant Nos. 50708055, 60774034 and 10872194)
文摘Modeling time headways between vehicles has attracted increasing interest in the traffic flow research field recently, because the corresponding statistics help to reveal the intrinsic interactions governing the vehicle dynamics. However, most previous micro-simulation models cannot yield the observed log-normal distributed headways. This paper designs a new car-following model inspired by the Galton board to reproduce the observed time-headway distributions as well as the complex traffic phenomena. The consistency between the empirical data and the simulation results indicates that this new car-following model provides a reasonable description of the car-following behaviours.
基金The NSF(11271155) of ChinaResearch Fund(20070183023) for the Doctoral Program of Higher Education
文摘In this paper, we propose a log-normal linear model whose errors are first-order correlated, and suggest a two-stage method for the efficient estimation of the conditional mean of the response variable at the original scale. We obtain two estimators which minimize the asymptotic mean squared error （MM） and the asymptotic bias （MB）, respectively. Both the estimators are very easy to implement, and simulation studies show that they are perform better.
文摘Medical research data are often skewed and heteroscedastic. It has therefore become practice to log-transform data in regression analysis, in order to stabilize the variance. Regression analysis on log-transformed data estimates the relative effect, whereas it is often the absolute effect of a predictor that is of interest. We propose a maximum likelihood (ML)-based approach to estimate a linear regression model on log-normal, heteroscedastic data. The new method was evaluated with a large simulation study. Log-normal observations were generated according to the simulation models and parameters were estimated using the new ML method, ordinary least-squares regression (LS) and weighed least-squares regression (WLS). All three methods produced unbiased estimates of parameters and expected response, and ML and WLS yielded smaller standard errors than LS. The approximate normality of the Wald statistic, used for tests of the ML estimates, in most situations produced correct type I error risk. Only ML and WLS produced correct confidence intervals for the estimated expected value. ML had the highest power for tests regarding β1.
文摘We have observed weather clutter containing targets (ships) using an S-band radar with a frequency 3.05 GHz, a beam width 1.8°, and a pulsewidth 0.5 μs. To investigate the weather clutter amplitude statistics, we introduce the Akaike Information Criterion (AIC). We have found that the weather clutter amplitudes obey the log-normal, Weibull, and log-Weibull distributions with the shape parameters of 0.308 to 0.470, 4.42 to 4.51, and 15.91 to 16.44, respectively, for small data within the beam width of an antenna. We have proposed the log-normal/CFAR circuit modified a Cell-Averaging (CA) LOG/CFAR circuit. It is found that weather clutter is suppressed with improvement of 51.58 dB by log-normal/CFAR. As a result, we have showed that weather clutter observed by S-band radar does not obey the Rayleigh distribution and our log-normal/CFAR circuit has an effect on suppression of clutter and detection of target, while conventional LOG/CFAR circuit does not. In addition, if our circuit can be realized, we will have an advantage economically.
基金supported by the Science and Technology Development Fund,Macao Special Administrative Region(SAR)(0093/2023/RIA2,0157/2024/RIA2,0145/2023/RIA3)the Distinguished Program of Obuda University and the DeSci Center for Parallel Intelligence at the Obuda University,Hungary.This article is based on the report of“Digital Theaters and Theatrical Intelligence for Decision Science”Project(DeSCII-0017-1023-2023,PI:Qinghua Ni)initiated by DeSci International.
文摘As Artificial Intelligence(AI)is moving fast from Large Language Models(LLMs)to AI Agents and Agentic Intelligence,the need to incorporate new AI into Decision Intelligence(DI)is becoming more and more urgent for both practical and theoretic reasons:both decision and process complexities would be significantly increased due to the use of advanced AI tools and agents,and both traditional and recent thinking must be rethought and reconstructed accordingly.Our perspective would like to address this important issue based on some historical milestone developments in Computer-Aided Software Engineering(CASE)and recent efforts in digital theatrical technology[1].
基金Estonian Research Competency Council,Grant/Award Number:PSG453,Eesti Teadusagentuur。
文摘Digital twin(DT)technology has been utilised in many applications including electric vehicles(EVs).A DT is a virtual representation of a physical object,enabled through real-time data integration,simulation,and optimisation tools.Unlike conventional simulations,which are typically offline and lack real-time interaction,a DT continuously synchronises with the physical system,enabling dynamic performance monitoring and predictive an-alytics.Achieving a full DT involves progressive stages,with the digital shadow(DS)being the final step before realising a bidirectional DT.Building a DS provides a scalable real-time performance monitoring and fault detection framework,enabling proactive decision-making in EV operations.This study introduces a DS system specifically designed to monitor the performance of a permanent magnet synchronous motor(PMSM)drive system in EVs,marking a critical phase towards a complete DT.The methodology for creating the DS is detailed,including the establishment of a compre-hensive test bench for the EV powertrain as the physical reference model.The mathe-matical model of the EV-PMSM was formulated,and an advanced estimation model utilising the extended Kalman filter(EKF)was implemented.MATLAB/Simulink was employed to develop the motor’s digital model.Real-time data acquisition from the physical model was facilitated through a data acquisition system(DAS)equipped with a controller area network(CAN)communication interface.The digital model underwent thorough validation against sensory data collected from the test bench.The motor digital model was deployed to a DS framework enabled through real-time data flow from the actual EV during real-world driving conditions.The results demonstrated a high accuracy of 97%between the DS predictions and the corresponding EV data,confirming the DS’s reliability.These findings pave the way for future advancements,including bidirectional interaction and the realisation of a full DT.
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/333/46。
文摘Verlinde's emergent gravity(VEG)posits that gravity arises as an emergent phenomenon rooted in the entropic properties of spacetime,challenging the traditional view of gravity as a fundamental force.Building on this paradigm,recent developments have introduced a novel class of black holes within the VEG framework,revealing intriguing connections between apparent dark matter effects and the distribution of baryonic matter.In this study,we delve into the observational signatures of a Simpson–Visser(SV)Minkowski core regular black hole in VEG,focusing on its shadow images and intensity profiles.Our analysis highlights the profound influence of model parameters,including A(governing baryonic matter distribution),B(strength of interaction between apparent dark matter and baryonic matter),and n(characterizing diverse spacetime geometries),on the effective potential and observable properties.Notably,we find that the modifications introduced by these parameters lead to distinct changes in the black hole's shadow size and intensity distribution.Comparing our results to the Reissner–Nordström(RN)black hole,we uncover a striking reduction in the apparent shadow size and an enhancement in intensity for the SV solution in VEG.
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper,we investigate the optical properties of a non-rotating charged black hole(BH)in the Einstein-Maxwell-scalar(EMS)theory,together with a plasma medium.We first consider the photon sphere and shadow radius under the impact of the plasma medium existing in the environment surrounding the BH in the EMS theory.We show that the radius of the photon sphere and the BH shadow decrease under the influence of the parameterβ.We further study gravitational weak lensing in detail by adapting general methods and derive the light ray's deflection angle around the BH together with the plasma environment.It is found that for uniform plasma,the deflection angle increases with the rise of the plasma parameter,whereas it decreases with the increase of the plasma parameter for non-uniform plasma.Besides,we also study the magnification of image brightness.
基金support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(2020395)Strategic Priority Research Program of the Chinese Academy of Sciences grant XDB 41000000(Y.L.)+4 种基金National Natural Science Foundation of China(Nos.42273042 and 41931077)"From 0 to 1"Original Exploration Cultivation Project,Institute of Geochemistry,Chinese Academy of Sciences(DHSZZ2023-3)Guizhou Provincial Foundation for Excellent Scholars Program(No.GCC[2023]088)Guizhou Provincial Science and Technology Projects:QKHJCZK[2023]-General 473NSFC Young Scientist Fund(Nos.42303041 and 42403043)。
文摘Permanently shadowed regions(PSRs)on the Moon are potential reservoirs for water ice,making them hot spots for future lunar exploration.The water ice in PSRs would cause distinctive changes in space weathering there,in particular reduction-oxidation processes that diff er from those in illuminated regions.To determine the characteristics of products formed during space weathering in PSRs,the lunar meteorite NWA 10203 with artifi cially added water was irradiated with a nanosecond laser to simulate a micro-meteorite bombardment of lunar soil containing water ice.The TEM results of the water-incorporated sample showed distinct amorphous rims that exhibited irregular thickness,poor stratifi cation,the appearance of bubbles,and a reduced number of npFe^(0).Additionally,EELS analysis showed the presence of ferric iron at the rim of the nanophase metallic iron particles(npFe^(0))in the amorphous rim with the involvement of water.The results suggest that water ice is another possible factor contributing to oxidation during micrometeorite bombardment on the lunar surface.In addition,it off ers a reference for a new space weathering model that incorporates water in PSRs,which could be widespread on asteroids with volatiles.
基金supported by the National Postdoctoral Fellowship of the Science and Engineering Research Board(SERB),Department of Science and Technology(DST),Government of India,File No.PDF/2021/003491。
文摘The photon region surrounding a black hole is crucial for distant observers to receive the emitted spectrum from its vicinity.This paper investigates the optical features of a regular spinning antide Sitter(AdS)black hole.These kinds of black holes hold deviation parameter k,and the cosmological constant A including their mass M and spin a.The cosmological parameter depends on the curvature radius by A=-3/l~2.We investigate the structure of geodesics for unstable circular orbits of photons as observed by an observer at specific Boyer-Lindquist coordinates(r_(O),v_(O))in the region between the outer and cosmological horizon,so-called the domain of outer communication.Our investigations include the analysis of three observables from its shadow plot:the black hole shadow radius(R_(s)),the distortion of the black hole(δ_(s)),and shadow area A.With the help of these observables,we calculate the angular diameter of the apparent size of the shadow.The shadows cast by spinning regular spacetimes are smaller compared to those produced by rotating black holes in both general relativity and regular spacetimes.We also calculate the rate at which energy is emitted from the black hole.
基金support of Dean Fund Project of the China National Institute of Standardization[Grant No.572025Y-12477]National Natural Science Foundation of China[Grant No.72204247].
文摘The marginal abatement cost(MAC)of CO_(2)emissions is one of the most critical indicators used to assess energy conservation and emission reduction.Although extensively measured,few studies have incorporated the influence of policy constraints when evaluating MAC.To address this gap,this paper proposes a nonparametric directional distance function approach under policy regulations to estimate the CO_(2)shadow price in the construction industry across 30 Chinese provinces from 2010 to 2017.Based on this enhanced method,four key findings emerge:①the annual CO_(2)shadow price exhibits an overall upward trend during the observation period;②regional shadow prices display marked variation across provinces;③regional heterogeneity in shadow prices has increased steadily over time;and④both urbanization rate and energy consumption per unit of gross domestic product are significantly negatively correlated with the CO_(2)shadow price.Finally,the paper offers several policy recommendations for CO_(2)emissions reduction in the Chinese construction industry at the national,industry,and enterprise levels.
