In 2019,the novel coronavirus disease 2019(COVID-19)ravaged the world.As of July 2021,there are about 192 million infected people worldwide and 4.1365 million deaths.At present,the new coronavirus is still spreading a...In 2019,the novel coronavirus disease 2019(COVID-19)ravaged the world.As of July 2021,there are about 192 million infected people worldwide and 4.1365 million deaths.At present,the new coronavirus is still spreading and circulating in many places around the world,especially since the emergence of Delta variant strains has increased the risk of the COVID-19 pandemic again.The symptoms of COVID-19 are diverse,and most patients have mild symptoms,with fever,dry cough,and fatigue as the main manifestations,and about 15.7%to 32.0%of patients will develop severe symptoms.Patients are screened in hospitals or primary care clinics as the initial step in the therapy for COVID-19.Although transcription-polymerase chain reaction(PCR)tests are still the primary method for making the final diagnosis,in hospitals today,the election protocol is based on medical imaging because it is quick and easy to use,which enables doctors to diagnose illnesses and their effects more quickly3.According to this approach,individuals who are thought to have COVID-19 first undergo an X-ray session and then,if further information is required,a CT-scan session.This methodology has led to a significant increase in the use of computed tomography scans(CT scans)and X-ray pictures in the clinic as substitute diagnostic methods for identifying COVID-19.To provide a significant collection of various datasets and methods used to diagnose COVID-19,this paper provides a comparative study of various state-of-the-art methods.The impact of medical imaging techniques on COVID-19 is also discussed.展开更多
This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a u...This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.展开更多
Spain is the leading producer of olive oil. For Spain, olive oil and olive growing are not only an important source of economic wealth, but also symbols of its culture and gastronomy renowned both nationally and inter...Spain is the leading producer of olive oil. For Spain, olive oil and olive growing are not only an important source of economic wealth, but also symbols of its culture and gastronomy renowned both nationally and internationally. However, in rural areas where the olive is the primary source of income for resident families, proposals are being sought for activities that break away from the seasonality in income represented by dependence on agriculture. Among all these proposals there is one that is oleotourism, which is beginning to gain ground because of its facet of culinary tourism. This is due to its uniqueness, and it can also be considered an initiative for sustainable rural tourism. Given the interest aroused by this type of initiative, both on the part of the public administration and also the olive sector, this study involves the demand for oleotourism in Andalucía and is a strategic analysis of oleotourism as a new market sector in the south of Spain.展开更多
It is commonly thought that the Michelson-Morley experiment from 1887 and Kennedy-Thorndike experiment from 1932 demonstrated that the universal frame of reference (ether) does not exist and that the velocity of light...It is commonly thought that the Michelson-Morley experiment from 1887 and Kennedy-Thorndike experiment from 1932 demonstrated that the universal frame of reference (ether) does not exist and that the velocity of light in vacuum is absolutely constant. The analysis of this experiment led to the creation of the Special Theory of Relativity (STR). The article explains why Michelson-Morley and Kennedy-Thorndike experiments could not detect the universal frame of reference. In this article, a different transformation of time and position than the Lorentz transformation is derived on the basis of the geometric analysis of the Michelson-Morley and Kennedy-Thorndike experiments. The transformation is derived based on the assumption that the universal frame of reference (UFR) exists. UFR is a frame of reference in which the velocity of light is constant in every direction. In inertial frames of reference moving in the UFR, the velocity of light may be different. The article has derived the formula for relative speed and patterns for the maximum and minimum speed of light that can be measured in the inertial system. Finally, the anisotropy of the microwave background radiation has been explained by using the presented theory. According to the body kinematics model presented in this article, anisotropy of cosmic microwave background is the Doppler effect for observer moving in the UFR.展开更多
In this paper,we apply the spatial panel model to explore the relationship between the dynamic of two types of crude oil prices(WTI and Brent crude oil)and their refined products over time.Considering the turbulent mo...In this paper,we apply the spatial panel model to explore the relationship between the dynamic of two types of crude oil prices(WTI and Brent crude oil)and their refined products over time.Considering the turbulent months of 2011,when Cushing Oklahoma had reached capacity and the crude oil export ban removal in 2015 as breakpoints,we apply this method both in the full sample and the three resultant regimes.First,results suggest our results show that both WTI and Brent display very similar behaviour with the refined products.Second,when attending to each regime,results derived from the first and third regimes are quite similar to the full sample results.Therefore,during the second regime,Brent crude oil became the benchmark in the petrol market,and it influenced the distillate products.Furthermore,our model can let us determine the price-setters and price-followers in the price formation mechanism through refined products.These results possess important considerations to policymakers and the market participants and the price formation.展开更多
AIM:To assess whether the use of porcine models is useful for learning endoscopic submucosal dissection(ESD),thus contributing to its subsequent application in human patients.METHODS:This study/learning process was ca...AIM:To assess whether the use of porcine models is useful for learning endoscopic submucosal dissection(ESD),thus contributing to its subsequent application in human patients.METHODS:This study/learning process was carried out in 3 phases:PhaseⅠ:Ex vivo animal;PhaseⅡ:In vivo animal;PhaseⅢ:Humans.One endoscopist performed 30 gastric ESDs in porcine models,and later 5gastric ESDs in 5 patients.The ESD was done following the method practiced at the National Cancer Center in Tokyo,Japan.Technical aspects,size,time and speed of ESD,as well as complications were registered.In patients,their clinical,endoscopic and histologic evolution was additionally added.RESULTS:Thirty en bloc ESDs were carried out in animal models.The mean±SD size of the pieces was of28.4±1.2 mm,and the time of ESD was 41.7±2.4min.The time of ESD in the first 15 procedures was 43.0±3.0 min whereas in the next 15 procedures,the time was 40.3±3.9 min,P=0.588.The speed in the first 15ESDs was 1.25±0.11 cm2/min vs 2.12±0.36 cm2/min in the remaining 15,P=0.028.There were no complications.In patients,5 lesions were resected en bloc.The size of the pieces was 25.2±5.1 mm and the time was85.0±25.6 min.Endoscopic and histological controls did not show evidence of residual neoplastic tissue.CONCLUSION:A sequential ESD training program of a unique endoscopist,based on the practice in porcine models,contributed to learning ESD for its subsequent application in humans,yielding good results in efficacy and safety.展开更多
The Covid-19 epidemic poses a serious public health threat to the world,where people with little or no pre-existing human immunity can be more vulnerable to its effects.Thus,developing surveillance systems for predict...The Covid-19 epidemic poses a serious public health threat to the world,where people with little or no pre-existing human immunity can be more vulnerable to its effects.Thus,developing surveillance systems for predicting the Covid-19 pandemic at an early stage could save millions of lives.In this study,a deep learning algorithm and a Holt-trend model are proposed to predict the coronavirus.The Long-Short Term Memory(LSTM)and Holttrend algorithms were applied to predict confirmed numbers and death cases.The real time data used has been collected from theWorld Health Organization(WHO).In the proposed research,we have considered three countries to test the proposed model,namely Saudi Arabia,Spain and Italy.The results suggest that the LSTM models show better performance in predicting the cases of coronavirus patients.Standard measure performance Mean squared Error(MSE),Root Mean Squared Error(RMSE),Mean error and correlation are employed to estimate the results of the proposed models.The empirical results of the LSTM,using the correlation metrics,are 99.94%,99.94%and 99.91%in predicting the number of confirmed cases in the three countries.As far as the results of the LSTM model in predicting the number of death of Covid-19,they are 99.86%,98.876%and 99.16%with respect to Saudi Arabia,Italy and Spain respectively.Similarly,the experiment’s results of the Holt-Trend model in predicting the number of confirmed cases of Covid-19,using the correlation metrics,are 99.06%,99.96%and 99.94%,whereas the results of the Holt-Trend model in predicting the number of death cases are 99.80%,99.96%and 99.94%with respect to the Saudi Arabia,Italy and Spain respectively.The empirical results indicate the efficient performance of the presented model in predicting the number of confirmed and death cases of Covid-19 in these countries.Such findings provide better insights regarding the future of Covid-19 this pandemic in general.The results were obtained by applying time series models,which need to be considered for the sake of saving the lives of many people.展开更多
Industrial internet of things (IIoT) is the usage of internet of things(IoT) devices and applications for the purpose of sensing, processing andcommunicating real-time events in the industrial system to reduce the unn...Industrial internet of things (IIoT) is the usage of internet of things(IoT) devices and applications for the purpose of sensing, processing andcommunicating real-time events in the industrial system to reduce the unnecessary operational cost and enhance manufacturing and other industrial-relatedprocesses to attain more profits. However, such IoT based smart industriesneed internet connectivity and interoperability which makes them susceptibleto numerous cyber-attacks due to the scarcity of computational resourcesof IoT devices and communication over insecure wireless channels. Therefore, this necessitates the design of an efficient security mechanism for IIoTenvironment. In this paper, we propose a hyperelliptic curve cryptography(HECC) based IIoT Certificateless Signcryption (IIoT-CS) scheme, with theaim of improving security while lowering computational and communicationoverhead in IIoT environment. HECC with 80-bit smaller key and parameterssizes offers similar security as elliptic curve cryptography (ECC) with 160-bitlong key and parameters sizes. We assessed the IIoT-CS scheme security byapplying formal and informal security evaluation techniques. We used Realor Random (RoR) model and the widely used automated validation of internet security protocols and applications (AVISPA) simulation tool for formalsecurity analysis and proved that the IIoT-CS scheme provides resistance tovarious attacks. Our proposed IIoT-CS scheme is relatively less expensivecompared to the current state-of-the-art in terms of computational cost andcommunication overhead. Furthermore, the IIoT-CS scheme is 31.25% and 51.31% more efficient in computational cost and communication overhead,respectively, compared to the most recent protocol.展开更多
This paper investigates the effect of the circular economy on CO_(2)emissions growth by considering the role of energy transition,climate policy stringency,industrialization,and supply chain pressure from 1997 to 2020...This paper investigates the effect of the circular economy on CO_(2)emissions growth by considering the role of energy transition,climate policy stringency,industrialization,and supply chain pressure from 1997 to 2020 using panel quantile Autoregressive Distributed Lags(QARDL)and the panel PMG.We employ cointegration association in the long run among the variables,and the results of the two models confirm this.Findings reveal that circular economy and climate policy stringency significantly negatively impact carbon emissions.On the other hand,the energy transition,industrialization,and supply chain pressures are crucial to determining CO_(2)emissions in the short and long run.The finding further explores that municipal waste generation recycling is considerable at the mean and upper 90th quantiles than the lower quantile.Therefore,the empirical results of the current study provide acumens for policymakers of advanced economies and emerging markets to maintain the balance among circular economy,energy transition,environmental policy stringency,and supply chain pressure for reducing CO_(2)emissions without halting economic growth and sustainable development.Furthermore,practical implications are reported through the lens of carbon neutrality and structural changes.展开更多
In this study,the relationships between five renewable energy sub-sectors markets and the geopolitical risk(GPR)and economic uncertainty indices(EUI)were examined using daily data from March 30,2012,to April 1,2022.Co...In this study,the relationships between five renewable energy sub-sectors markets and the geopolitical risk(GPR)and economic uncertainty indices(EUI)were examined using daily data from March 30,2012,to April 1,2022.Convergent cross mapping results show that the renewable energy indices have definite relationships with the GPR and EUI.The renewable energy indices show differences in response directions,speed and trends for a standard information difference impulse from the GPR and the EUI.A positive dynamic conditional correlation between renewable energies and EUI was observed in the first and second waves of the COVID-19 outbreak.In contrast,there was a relatively decreased effect for two risk indices during the Russia-Ukraine conflict of February-March 2022.Our results show that renewable energy may act as a time-varying hedge against economic uncertainty and GPR owing to its safehaven properties at various scales.Moreover,building more secure and reliable renewable energy systems can help countries to increase their energy independence,which protects them against the risks of political and economic uncertainty.展开更多
With the ever growth of Internet users,video applications,and massive data traffic across the network,there is a higher need for reliable bandwidth-efficient multimedia communication.Versatile Video Coding(VVC/H.266)i...With the ever growth of Internet users,video applications,and massive data traffic across the network,there is a higher need for reliable bandwidth-efficient multimedia communication.Versatile Video Coding(VVC/H.266)is finalized in September 2020 providing significantly greater compression efficiency compared to Highest Efficient Video Coding(HEVC)while providing versatile effective use for Ultra-High Definition(HD)videos.This article analyzes the quality performance of convolutional codes,turbo codes and self-concatenated convolutional(SCC)codes based on performance metrics for reliable future video communication.The advent of turbo codes was a significant achievement ever in the era of wireless communication approaching nearly the Shannon limit.Turbo codes are operated by the deployment of an interleaver between two Recursive Systematic Convolutional(RSC)encoders in a parallel fashion.Constituent RSC encoders may be operating on the same or different architectures and code rates.The proposed work utilizes the latest source compression standards H.266 and H.265 encoded standards and Sphere Packing modulation aided differential Space Time Spreading(SP-DSTS)for video transmission in order to provide bandwidth-efficient wireless video communication.Moreover,simulation results show that turbo codes defeat convolutional codes with an averaged E_(b)/N_(0) gain of 1.5 dB while convolutional codes outperformcompared to SCC codes with an E_(b)/N_(0) gain of 3.5 dBatBit ErrorRate(BER)of 10−4.The Peak Signal to Noise Ratio(PSNR)results of convolutional codes with the latest source coding standard of H.266 is plotted against convolutional codes with H.265 and it was concluded H.266 outperform with about 6 dB PSNR gain at E_(b)/N_(0) value of 4.5 dB.展开更多
Blockchain is one of the innovative and disruptive technologies that has a wide range of applications in multiple industries beyond cryptocurrency.The widespread adoption of blockchain technology in various industries...Blockchain is one of the innovative and disruptive technologies that has a wide range of applications in multiple industries beyond cryptocurrency.The widespread adoption of blockchain technology in various industries has shown its potential to solve challenging business problems,as well as the possibility to create new business models which can increase a firm’s competitiveness.Due to the novelty of the technology,whereby many companies are still exploring potential use cases,and considering the complexity of blockchain technology,which may require huge changes to a company’s existing systems and processes,it is important for companies to carefully evaluate suitable use cases and determine if blockchain technology is the best solution for their specific needs.This research aims to provide an evaluation framework that determines the important dimensions of blockchain suitability assessment by identifying the key determinants of suitable use cases in a business context.In this paper,a novel approach that utilizes both qualitative(Delphi method)and quantitative(fuzzy set theory)methods has been proposed to objectively account for the uncertainty associated with data collection and the vagueness of subjective judgments.This work started by scanning available literature to identify major suitability dimensions and collected a range of criteria,indicators,and factors that had been previously identified for related purposes.Expert opinions were then gathered using a questionnaire to rank the importance and relevance of these elements to suitability decisions.Subsequently,the data were analyzed and we proceeded to integrate multi-criteria group decision-making(MCGDM)and intuitionistic fuzzy set(IFS)theory.The findings demonstrated a high level of agreement among experts,with the model being extremely sensitive to variances in expert assessments.Furthermore,the results helped to refine and select the most relevant suitability determinants under three important dimensions:functional suitability of the use case,organizational applicability,and ecosystem readiness.展开更多
In Wireless Sensor Network(WSN),coverage and connectivity are the vital challenges in the target-based region.The linear objective is to find the positions to cover the complete target nodes and connectivity between e...In Wireless Sensor Network(WSN),coverage and connectivity are the vital challenges in the target-based region.The linear objective is to find the positions to cover the complete target nodes and connectivity between each sensor for data forwarding towards the base station given a grid with target points and a potential sensor placement position.In this paper,a multiobjective problem on target-based WSN(t-WSN)is derived,which minimizes the number of deployed nodes,and maximizes the cost of coverage and sensing range.An Evolutionary-based Non-Dominated Sorting Genetic Algorithm-II(NSGA-II)is incorporated to tackle this multiobjective problem efficiently.Multiobjective problems are intended to solve different objectives of a problem simultaneously.Bio-inspired algorithms address the NP-hard problem most effectively in recent years.In NSGA-II,the Non-Dominated sorting preserves the better solution in different objectives simultaneously using dominance relation.In the diversity maintenance phase,density estimation and crowd comparison are the two components that balance the exploration and exploitation phase of the algorithm.Performance of NSGA-II on this multiobjective problem is evaluated in terms of performance indicators Overall Non-dominated Vector Generation(ONGV)and Spacing(SP).The simulation results show the proposed method performs outperforms the existing algorithms in different aspects of the model.展开更多
Our research focuses on the development of two cooperative approaches for resolution of the multi-item capacitated lot-sizing problems with time windows and setup times (MICLSP-TW-ST). In this paper we combine variabl...Our research focuses on the development of two cooperative approaches for resolution of the multi-item capacitated lot-sizing problems with time windows and setup times (MICLSP-TW-ST). In this paper we combine variable neighborhood search and accurate mixed integer programming (VNS-MIP) to solve MICLSP-TW-ST. It concerns so a particularly important and difficult problem in production planning. This problem is NP-hard in the strong sense. Moreover, it is very difficult to solve with an exact method;it is for that reason we have made use of the approximate methods. We improved the variable neighborhood search (VNS) algorithm, which is efficient for solving hard combinatorial optimization problems. This problem can be viewed as an optimization problem with mixed variables (binary variables and real variables). The new VNS algorithm was tested against 540 benchmark problems. The performance of most of our approaches was satisfactory and performed better than the algorithms already proposed in the literature.展开更多
The present study deals with the flow of blood through a stenotic artery in the presence of a uniform magnetic field. Different flow situations are taken into account by considering the regular and irregular shapes of...The present study deals with the flow of blood through a stenotic artery in the presence of a uniform magnetic field. Different flow situations are taken into account by considering the regular and irregular shapes of stenosis lying inside the walls of artery. Blood inside the artery is assumed to be Eyring-Powell fluid. A mathematical model is developed and simplified under the physical assumptions of stenosis. The regular perturbation method is adopted to find the solutions for axial velocity and pressure gradient. The variations in pressure drop across the stenosis length, the impedance and the shear stress at the walls of stenotic artery are discussed in detail through graphs. It is observed that the Eyring-Powell fluid is helpful in reducing the resistance to the flow in stenotic artery. Moreover, symmetric form of stenosis is more hazardous as compared to asymmetric stenosis.展开更多
How do people talk about COVID-19 online?To address this question,we offer an unsupervised framework that allows us to examine Twitter framings of the pandemic.Our approach employs a network-based exploration of socia...How do people talk about COVID-19 online?To address this question,we offer an unsupervised framework that allows us to examine Twitter framings of the pandemic.Our approach employs a network-based exploration of social media data to identify,categorize,and understand communication patterns about the novel coronavirus on Twitter.The simplest structure that emerges from our analysis is the distinction between the internal/personal,external/global,and generic threat framings of the pandemic.This structure replicates in different Twitter samples and is validated using the variation of information measure,reflecting the significance and stability of our findings.Such an exploratory study is useful for understanding the contours of the natural,non-random structure in this online space.We contend that this understanding of structure is necessary to address a host of causal,supervised,and related questions downstream.展开更多
Studies have investigated the effects of heat and temperature variability(TV)on mortality.However,few assessed whether TV modifies the heat-mortality association.Data on daily temperature and mortality in the warm sea...Studies have investigated the effects of heat and temperature variability(TV)on mortality.However,few assessed whether TV modifies the heat-mortality association.Data on daily temperature and mortality in the warm season were collected from 717 locations across 36 countries.TV was calculated as the standard deviation of the average of the same and previous days’minimum and maximum temperatures.展开更多
基金This research project was funded by the Deanship of Scientific Research,Princess Nourah bint Abdulrahman University,through the Program of Research Project Funding After Publication,grant No(43-PRFA-P-42)。
文摘In 2019,the novel coronavirus disease 2019(COVID-19)ravaged the world.As of July 2021,there are about 192 million infected people worldwide and 4.1365 million deaths.At present,the new coronavirus is still spreading and circulating in many places around the world,especially since the emergence of Delta variant strains has increased the risk of the COVID-19 pandemic again.The symptoms of COVID-19 are diverse,and most patients have mild symptoms,with fever,dry cough,and fatigue as the main manifestations,and about 15.7%to 32.0%of patients will develop severe symptoms.Patients are screened in hospitals or primary care clinics as the initial step in the therapy for COVID-19.Although transcription-polymerase chain reaction(PCR)tests are still the primary method for making the final diagnosis,in hospitals today,the election protocol is based on medical imaging because it is quick and easy to use,which enables doctors to diagnose illnesses and their effects more quickly3.According to this approach,individuals who are thought to have COVID-19 first undergo an X-ray session and then,if further information is required,a CT-scan session.This methodology has led to a significant increase in the use of computed tomography scans(CT scans)and X-ray pictures in the clinic as substitute diagnostic methods for identifying COVID-19.To provide a significant collection of various datasets and methods used to diagnose COVID-19,this paper provides a comparative study of various state-of-the-art methods.The impact of medical imaging techniques on COVID-19 is also discussed.
文摘This paper presents a comprehensive study that includes the sizing and power flow by series and parallel inverters in a distributed generation system(DGs)that integrates the system of hybrid wind photovoltaic with a unified power quality conditioner(UPQC).In addition to supplying active power to the utility grid,the system of hybrid wind photovoltaic functions as a UPQC,compensating reactive power and suppressing the harmonic load currents.Additionally,the load is supplied with harmonic-free,balanced and regulated output voltages.Since PVWind-UPQC is established on a dual compensation scheme,the series inverter works like a sinusoidal current source,while the parallel inverter works like a sinusoidal voltage source.Consequently,a smooth alteration from interconnected operating modes to island operating modes and vice versa can be achieved without load voltage transients.Since PV-Wind-UPQC inverters handle the energy generated through the hybrid wind photovoltaic system and the energy demanded through the load,the converters should be sized cautiously.A detailed study of the flow of power via the PV-Wind-UPQC is imperative to gain a complete understanding of the system operation and the proper design of the converters.Thus,curves that allow the sizing of the power converters according to the power flow via the converters are presented and discussed.Simulation results are presented to assess both steady state and dynamic performances of the grid connected hybrid system of PV-Wind-UPQC.This investigation is verified by simulating and analyzing the results with Matlab/Simulink.
文摘Spain is the leading producer of olive oil. For Spain, olive oil and olive growing are not only an important source of economic wealth, but also symbols of its culture and gastronomy renowned both nationally and internationally. However, in rural areas where the olive is the primary source of income for resident families, proposals are being sought for activities that break away from the seasonality in income represented by dependence on agriculture. Among all these proposals there is one that is oleotourism, which is beginning to gain ground because of its facet of culinary tourism. This is due to its uniqueness, and it can also be considered an initiative for sustainable rural tourism. Given the interest aroused by this type of initiative, both on the part of the public administration and also the olive sector, this study involves the demand for oleotourism in Andalucía and is a strategic analysis of oleotourism as a new market sector in the south of Spain.
文摘It is commonly thought that the Michelson-Morley experiment from 1887 and Kennedy-Thorndike experiment from 1932 demonstrated that the universal frame of reference (ether) does not exist and that the velocity of light in vacuum is absolutely constant. The analysis of this experiment led to the creation of the Special Theory of Relativity (STR). The article explains why Michelson-Morley and Kennedy-Thorndike experiments could not detect the universal frame of reference. In this article, a different transformation of time and position than the Lorentz transformation is derived on the basis of the geometric analysis of the Michelson-Morley and Kennedy-Thorndike experiments. The transformation is derived based on the assumption that the universal frame of reference (UFR) exists. UFR is a frame of reference in which the velocity of light is constant in every direction. In inertial frames of reference moving in the UFR, the velocity of light may be different. The article has derived the formula for relative speed and patterns for the maximum and minimum speed of light that can be measured in the inertial system. Finally, the anisotropy of the microwave background radiation has been explained by using the presented theory. According to the body kinematics model presented in this article, anisotropy of cosmic microwave background is the Doppler effect for observer moving in the UFR.
文摘In this paper,we apply the spatial panel model to explore the relationship between the dynamic of two types of crude oil prices(WTI and Brent crude oil)and their refined products over time.Considering the turbulent months of 2011,when Cushing Oklahoma had reached capacity and the crude oil export ban removal in 2015 as breakpoints,we apply this method both in the full sample and the three resultant regimes.First,results suggest our results show that both WTI and Brent display very similar behaviour with the refined products.Second,when attending to each regime,results derived from the first and third regimes are quite similar to the full sample results.Therefore,during the second regime,Brent crude oil became the benchmark in the petrol market,and it influenced the distillate products.Furthermore,our model can let us determine the price-setters and price-followers in the price formation mechanism through refined products.These results possess important considerations to policymakers and the market participants and the price formation.
基金Supported by Department of GastroenterologyHospital de Clínicas+1 种基金MontevideoUruguay
文摘AIM:To assess whether the use of porcine models is useful for learning endoscopic submucosal dissection(ESD),thus contributing to its subsequent application in human patients.METHODS:This study/learning process was carried out in 3 phases:PhaseⅠ:Ex vivo animal;PhaseⅡ:In vivo animal;PhaseⅢ:Humans.One endoscopist performed 30 gastric ESDs in porcine models,and later 5gastric ESDs in 5 patients.The ESD was done following the method practiced at the National Cancer Center in Tokyo,Japan.Technical aspects,size,time and speed of ESD,as well as complications were registered.In patients,their clinical,endoscopic and histologic evolution was additionally added.RESULTS:Thirty en bloc ESDs were carried out in animal models.The mean±SD size of the pieces was of28.4±1.2 mm,and the time of ESD was 41.7±2.4min.The time of ESD in the first 15 procedures was 43.0±3.0 min whereas in the next 15 procedures,the time was 40.3±3.9 min,P=0.588.The speed in the first 15ESDs was 1.25±0.11 cm2/min vs 2.12±0.36 cm2/min in the remaining 15,P=0.028.There were no complications.In patients,5 lesions were resected en bloc.The size of the pieces was 25.2±5.1 mm and the time was85.0±25.6 min.Endoscopic and histological controls did not show evidence of residual neoplastic tissue.CONCLUSION:A sequential ESD training program of a unique endoscopist,based on the practice in porcine models,contributed to learning ESD for its subsequent application in humans,yielding good results in efficacy and safety.
文摘The Covid-19 epidemic poses a serious public health threat to the world,where people with little or no pre-existing human immunity can be more vulnerable to its effects.Thus,developing surveillance systems for predicting the Covid-19 pandemic at an early stage could save millions of lives.In this study,a deep learning algorithm and a Holt-trend model are proposed to predict the coronavirus.The Long-Short Term Memory(LSTM)and Holttrend algorithms were applied to predict confirmed numbers and death cases.The real time data used has been collected from theWorld Health Organization(WHO).In the proposed research,we have considered three countries to test the proposed model,namely Saudi Arabia,Spain and Italy.The results suggest that the LSTM models show better performance in predicting the cases of coronavirus patients.Standard measure performance Mean squared Error(MSE),Root Mean Squared Error(RMSE),Mean error and correlation are employed to estimate the results of the proposed models.The empirical results of the LSTM,using the correlation metrics,are 99.94%,99.94%and 99.91%in predicting the number of confirmed cases in the three countries.As far as the results of the LSTM model in predicting the number of death of Covid-19,they are 99.86%,98.876%and 99.16%with respect to Saudi Arabia,Italy and Spain respectively.Similarly,the experiment’s results of the Holt-Trend model in predicting the number of confirmed cases of Covid-19,using the correlation metrics,are 99.06%,99.96%and 99.94%,whereas the results of the Holt-Trend model in predicting the number of death cases are 99.80%,99.96%and 99.94%with respect to the Saudi Arabia,Italy and Spain respectively.The empirical results indicate the efficient performance of the presented model in predicting the number of confirmed and death cases of Covid-19 in these countries.Such findings provide better insights regarding the future of Covid-19 this pandemic in general.The results were obtained by applying time series models,which need to be considered for the sake of saving the lives of many people.
基金This work is supported by the University of Malaya IIRG Grant(IIRG008A-19IISSN),Ministry of Education FRGS Grant(FP055-2019A)This work was also supported by Grant System of University of Zilina No.1/2020.(Project No.7962)partially supported by the Slovak Grant Agency for Science(VEGA)under Grant Number 1/0157/21.The authors are grateful to the Taif University Researchers Supporting Project(Number TURSP-2020/36),Taif University,Taif,Saudi Arabia.
文摘Industrial internet of things (IIoT) is the usage of internet of things(IoT) devices and applications for the purpose of sensing, processing andcommunicating real-time events in the industrial system to reduce the unnecessary operational cost and enhance manufacturing and other industrial-relatedprocesses to attain more profits. However, such IoT based smart industriesneed internet connectivity and interoperability which makes them susceptibleto numerous cyber-attacks due to the scarcity of computational resourcesof IoT devices and communication over insecure wireless channels. Therefore, this necessitates the design of an efficient security mechanism for IIoTenvironment. In this paper, we propose a hyperelliptic curve cryptography(HECC) based IIoT Certificateless Signcryption (IIoT-CS) scheme, with theaim of improving security while lowering computational and communicationoverhead in IIoT environment. HECC with 80-bit smaller key and parameterssizes offers similar security as elliptic curve cryptography (ECC) with 160-bitlong key and parameters sizes. We assessed the IIoT-CS scheme security byapplying formal and informal security evaluation techniques. We used Realor Random (RoR) model and the widely used automated validation of internet security protocols and applications (AVISPA) simulation tool for formalsecurity analysis and proved that the IIoT-CS scheme provides resistance tovarious attacks. Our proposed IIoT-CS scheme is relatively less expensivecompared to the current state-of-the-art in terms of computational cost andcommunication overhead. Furthermore, the IIoT-CS scheme is 31.25% and 51.31% more efficient in computational cost and communication overhead,respectively, compared to the most recent protocol.
文摘This paper investigates the effect of the circular economy on CO_(2)emissions growth by considering the role of energy transition,climate policy stringency,industrialization,and supply chain pressure from 1997 to 2020 using panel quantile Autoregressive Distributed Lags(QARDL)and the panel PMG.We employ cointegration association in the long run among the variables,and the results of the two models confirm this.Findings reveal that circular economy and climate policy stringency significantly negatively impact carbon emissions.On the other hand,the energy transition,industrialization,and supply chain pressures are crucial to determining CO_(2)emissions in the short and long run.The finding further explores that municipal waste generation recycling is considerable at the mean and upper 90th quantiles than the lower quantile.Therefore,the empirical results of the current study provide acumens for policymakers of advanced economies and emerging markets to maintain the balance among circular economy,energy transition,environmental policy stringency,and supply chain pressure for reducing CO_(2)emissions without halting economic growth and sustainable development.Furthermore,practical implications are reported through the lens of carbon neutrality and structural changes.
基金supported by the Ministry of Education of the People’s Republic of China Humanities and Social Sciences Youth Foundation(Grant No.22YJC910014)the Social Sciences Planning Youth Project of Anhui Province(Grant No.AHSKQ2022D138)+2 种基金the Anhui Province Excellent Young Talents Fund Program of Higher Education Institutions(Grant No.2023AH030015)the Innovation Development Research Project of Anhui Province(Grant No.2023CX507)the National Natural Science Foundation of China(Grant No.71934001).
文摘In this study,the relationships between five renewable energy sub-sectors markets and the geopolitical risk(GPR)and economic uncertainty indices(EUI)were examined using daily data from March 30,2012,to April 1,2022.Convergent cross mapping results show that the renewable energy indices have definite relationships with the GPR and EUI.The renewable energy indices show differences in response directions,speed and trends for a standard information difference impulse from the GPR and the EUI.A positive dynamic conditional correlation between renewable energies and EUI was observed in the first and second waves of the COVID-19 outbreak.In contrast,there was a relatively decreased effect for two risk indices during the Russia-Ukraine conflict of February-March 2022.Our results show that renewable energy may act as a time-varying hedge against economic uncertainty and GPR owing to its safehaven properties at various scales.Moreover,building more secure and reliable renewable energy systems can help countries to increase their energy independence,which protects them against the risks of political and economic uncertainty.
基金supported by the Ministry of Education of the Czech Republic(Project No.SP2022/18 and No.SP2022/5)by the European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project,project number CZ.02.1.01/0.0/0.0/16019/0000867 within the Operational Programme Research,Development,and Education.
文摘With the ever growth of Internet users,video applications,and massive data traffic across the network,there is a higher need for reliable bandwidth-efficient multimedia communication.Versatile Video Coding(VVC/H.266)is finalized in September 2020 providing significantly greater compression efficiency compared to Highest Efficient Video Coding(HEVC)while providing versatile effective use for Ultra-High Definition(HD)videos.This article analyzes the quality performance of convolutional codes,turbo codes and self-concatenated convolutional(SCC)codes based on performance metrics for reliable future video communication.The advent of turbo codes was a significant achievement ever in the era of wireless communication approaching nearly the Shannon limit.Turbo codes are operated by the deployment of an interleaver between two Recursive Systematic Convolutional(RSC)encoders in a parallel fashion.Constituent RSC encoders may be operating on the same or different architectures and code rates.The proposed work utilizes the latest source compression standards H.266 and H.265 encoded standards and Sphere Packing modulation aided differential Space Time Spreading(SP-DSTS)for video transmission in order to provide bandwidth-efficient wireless video communication.Moreover,simulation results show that turbo codes defeat convolutional codes with an averaged E_(b)/N_(0) gain of 1.5 dB while convolutional codes outperformcompared to SCC codes with an E_(b)/N_(0) gain of 3.5 dBatBit ErrorRate(BER)of 10−4.The Peak Signal to Noise Ratio(PSNR)results of convolutional codes with the latest source coding standard of H.266 is plotted against convolutional codes with H.265 and it was concluded H.266 outperform with about 6 dB PSNR gain at E_(b)/N_(0) value of 4.5 dB.
文摘Blockchain is one of the innovative and disruptive technologies that has a wide range of applications in multiple industries beyond cryptocurrency.The widespread adoption of blockchain technology in various industries has shown its potential to solve challenging business problems,as well as the possibility to create new business models which can increase a firm’s competitiveness.Due to the novelty of the technology,whereby many companies are still exploring potential use cases,and considering the complexity of blockchain technology,which may require huge changes to a company’s existing systems and processes,it is important for companies to carefully evaluate suitable use cases and determine if blockchain technology is the best solution for their specific needs.This research aims to provide an evaluation framework that determines the important dimensions of blockchain suitability assessment by identifying the key determinants of suitable use cases in a business context.In this paper,a novel approach that utilizes both qualitative(Delphi method)and quantitative(fuzzy set theory)methods has been proposed to objectively account for the uncertainty associated with data collection and the vagueness of subjective judgments.This work started by scanning available literature to identify major suitability dimensions and collected a range of criteria,indicators,and factors that had been previously identified for related purposes.Expert opinions were then gathered using a questionnaire to rank the importance and relevance of these elements to suitability decisions.Subsequently,the data were analyzed and we proceeded to integrate multi-criteria group decision-making(MCGDM)and intuitionistic fuzzy set(IFS)theory.The findings demonstrated a high level of agreement among experts,with the model being extremely sensitive to variances in expert assessments.Furthermore,the results helped to refine and select the most relevant suitability determinants under three important dimensions:functional suitability of the use case,organizational applicability,and ecosystem readiness.
基金This research has been funded with the support of the project SP2021/45,assigned to VSB-Technical University of Ostrava,the Ministry of Education,Youth and Sports in the Czech Republic.
文摘In Wireless Sensor Network(WSN),coverage and connectivity are the vital challenges in the target-based region.The linear objective is to find the positions to cover the complete target nodes and connectivity between each sensor for data forwarding towards the base station given a grid with target points and a potential sensor placement position.In this paper,a multiobjective problem on target-based WSN(t-WSN)is derived,which minimizes the number of deployed nodes,and maximizes the cost of coverage and sensing range.An Evolutionary-based Non-Dominated Sorting Genetic Algorithm-II(NSGA-II)is incorporated to tackle this multiobjective problem efficiently.Multiobjective problems are intended to solve different objectives of a problem simultaneously.Bio-inspired algorithms address the NP-hard problem most effectively in recent years.In NSGA-II,the Non-Dominated sorting preserves the better solution in different objectives simultaneously using dominance relation.In the diversity maintenance phase,density estimation and crowd comparison are the two components that balance the exploration and exploitation phase of the algorithm.Performance of NSGA-II on this multiobjective problem is evaluated in terms of performance indicators Overall Non-dominated Vector Generation(ONGV)and Spacing(SP).The simulation results show the proposed method performs outperforms the existing algorithms in different aspects of the model.
文摘Our research focuses on the development of two cooperative approaches for resolution of the multi-item capacitated lot-sizing problems with time windows and setup times (MICLSP-TW-ST). In this paper we combine variable neighborhood search and accurate mixed integer programming (VNS-MIP) to solve MICLSP-TW-ST. It concerns so a particularly important and difficult problem in production planning. This problem is NP-hard in the strong sense. Moreover, it is very difficult to solve with an exact method;it is for that reason we have made use of the approximate methods. We improved the variable neighborhood search (VNS) algorithm, which is efficient for solving hard combinatorial optimization problems. This problem can be viewed as an optimization problem with mixed variables (binary variables and real variables). The new VNS algorithm was tested against 540 benchmark problems. The performance of most of our approaches was satisfactory and performed better than the algorithms already proposed in the literature.
文摘The present study deals with the flow of blood through a stenotic artery in the presence of a uniform magnetic field. Different flow situations are taken into account by considering the regular and irregular shapes of stenosis lying inside the walls of artery. Blood inside the artery is assumed to be Eyring-Powell fluid. A mathematical model is developed and simplified under the physical assumptions of stenosis. The regular perturbation method is adopted to find the solutions for axial velocity and pressure gradient. The variations in pressure drop across the stenosis length, the impedance and the shear stress at the walls of stenotic artery are discussed in detail through graphs. It is observed that the Eyring-Powell fluid is helpful in reducing the resistance to the flow in stenotic artery. Moreover, symmetric form of stenosis is more hazardous as compared to asymmetric stenosis.
文摘How do people talk about COVID-19 online?To address this question,we offer an unsupervised framework that allows us to examine Twitter framings of the pandemic.Our approach employs a network-based exploration of social media data to identify,categorize,and understand communication patterns about the novel coronavirus on Twitter.The simplest structure that emerges from our analysis is the distinction between the internal/personal,external/global,and generic threat framings of the pandemic.This structure replicates in different Twitter samples and is validated using the variation of information measure,reflecting the significance and stability of our findings.Such an exploratory study is useful for understanding the contours of the natural,non-random structure in this online space.We contend that this understanding of structure is necessary to address a host of causal,supervised,and related questions downstream.
基金This study was supported by the Australian Research Council(DP210102076)the Australian National Health and Medical Research Council(APP2000581)+12 种基金Y.W and B.W.were supported by the China Scholarship Council(nos.202006010044 and 202006010043)S.L.was supported by an Emerging Leader Fellowship of the Australian National Health and Medical Research Council(no.APP2009866)Y.G.was supported by Career Development Fellowship(no.APP1163693)and Leader Fellowship(no.APP2008813)of the Australian National Health and Medical Research CouncilJ.K.and A.U.were supported by the Czech Science Foundation(project no.20-28560S)N.S.was supported by the National Institute of Environmental Health Sciences-funded HERCULES Center(no.P30ES019776)Y.H.was supported by the Environment Research and Technology Development Fund(JPMEERF15S11412)of the Environmental Restoration and Conservation AgencyM.d.S.Z.S.C.and P.H.N.S.were supported by the São Paulo Research Foundation(FAPESP)H.O.and E.I.were supported by the Estonian Ministry of Education and Research(IUT34-17)J.M.was supported by a fellowship of Fundação para a Ciência e a Tecnlogia(SFRH/BPD/115112/2016)A.G.and F.S.were supported by the Medical Research Council UK(grant ID MR/R013349/1),the Natural Environment Research Council UK(grant ID NE/R009384/1),and the EU’s Horizon 2020 project,Exhaustion(grant ID 820655)A.S.and F.d.D.were supported by the EU’s Horizon 2020 project,Exhaustion(grant ID 820655)V.H.was supported by the Spanish Ministry of Economy,Industry and Competitiveness(grant ID PCIN-2017-046)A.T.byMCIN/AEI/10.13039/501100011033(grant CEX2018-000794-S).Statistics South Africa kindly provided the mortality data,but had no other role in the study.
文摘Studies have investigated the effects of heat and temperature variability(TV)on mortality.However,few assessed whether TV modifies the heat-mortality association.Data on daily temperature and mortality in the warm season were collected from 717 locations across 36 countries.TV was calculated as the standard deviation of the average of the same and previous days’minimum and maximum temperatures.
