Applying new approaches, methods, and technologies for the estimation of reserves can effectively improve the efficiency and accuracy of assessments of solid mineral resources. After analyzing the development of 3-D g...Applying new approaches, methods, and technologies for the estimation of reserves can effectively improve the efficiency and accuracy of assessments of solid mineral resources. After analyzing the development of 3-D geoscience modeling technology （3-D GMT）, this paper discusses the application of 3-D GMT for the estimation of solid mineral reserves, emphatically introducing its workflow and two key technologies, 3-D orebody surface modeling, and property modeling. Moreover, the paper analyzes the limitations of traditional methods, such as the section method and geological block method, and points out the advantages of 3-D GMT： building more accurate 3-D orebody models, expressing the internal inhomogeneous attributes of an orebody, reducing the potential for errors in the estimation of reserves, and implementing dynamic estimations of reserves.展开更多
In this paper, we propose a hybrid PML （H-PML） combining the normal absorption factor of convolutional PML （C-PML） with tangential absorption factor of Mutiaxial PML （M-PML）. The H-PML boundary conditions can be...In this paper, we propose a hybrid PML （H-PML） combining the normal absorption factor of convolutional PML （C-PML） with tangential absorption factor of Mutiaxial PML （M-PML）. The H-PML boundary conditions can better suppress the numerical instability in some extreme models, and the computational speed of finite-element method and the dynamic range are greatly increased using this HPML. We use the finite-element method with a hybrid PML to model the acoustic reflection of the interface when wireline and well logging while drilling （LWD）, in a formation with a reflector outside the borehole. The simulation results suggests that the PS- and SP- reflected waves arrive at the same time when the inclination between the well and the outer interface is zero, and the difference in arrival times increases with increasing dip angle. When there are fractures outside the well, the reflection signal is clearer in the subsequent reflection waves and may be used to identify the fractured zone. The difference between the dominant wavelength and the model scale shows that LWD reflection logging data are of higher resolution and quality than wireline acoustic reflection logging.展开更多
This paper proposes a hybrid layered asymmetrically clipped optical(HLACO) single-carrier frequency-division multiplexing(SCFDM) scheme for dimmable visible light communication. It designs a signal structure that comb...This paper proposes a hybrid layered asymmetrically clipped optical(HLACO) single-carrier frequency-division multiplexing(SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines layered asymmetrically clipped optical(LACO)-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency-division multiplexing(OFDM)-based dimmable schemes and further enhancing the system performance. Compared to the HLACO-OFDM-based dimming scheme, it obtains a lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit·s^(-1)·Hz^(-1) within the dimming range of 30%–70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.展开更多
Increasing popularity of spectrum-based services brings the striking contradictions between the limited spectrum resource and its increasing demands.This paper puts forward an approach to forecast the future spectrum ...Increasing popularity of spectrum-based services brings the striking contradictions between the limited spectrum resource and its increasing demands.This paper puts forward an approach to forecast the future spectrum demand and its economic value,so as to offer a scientific basis for spectrum regulators to resolve this contradiction effectively and make a long-term spectrum-use plan.Specifically,this paper analyzes the driving factors of spectrum demand firstly,based on which a forecasting model is constructed to predict the spectrum demand and its deficit/surplus in the next few years.Then,a forecasting model to measure the economic value of spectrum is proposed based on marginal opportunity cost theory,and the indifference curve is introduced to show the economic value generated by additional spectrum.Additionally,an empirical study is conducted to forecast the spectrum demand and its economic value for China in the next 10 years according to the proposed method.The results of this study show that spectrum deficit is a trend in future and releasing additional spectrum will bring China huge economic benefits.展开更多
In December 2019,an outbreak of pneumonia,which was named COVID-2019,emerged as a global health crisis.Scientists worldwide are engaged in attempts to elucidate the transmission and pathogenic mechanisms of the causat...In December 2019,an outbreak of pneumonia,which was named COVID-2019,emerged as a global health crisis.Scientists worldwide are engaged in attempts to elucidate the transmission and pathogenic mechanisms of the causative coronavirus.COVID-19 was declared a pandemic by the World Health Organization in March 2020,making it critical to track and review the state of research on COVID-19 to provide guidance for further investigations.Here,bibliometric and knowledge mapping analyses of studies on COVID-19 were performed,including more than 1,500 papers on COVID-19 available in the PubMed and China National Knowledge Infrastructure databases from January 1,2020 to March 8,2020.In this review,we found that because of the rapid response of researchers worldwide,the number of COVID-19-related publications showed a high growth trend in the first 10 days of February;among these,the largest number of studies originated in China,the country most affected by pandemic in its early stages.Our findings revealed that the epidemic situation and data accessibility of different research teams have caused obvious difference in emphases of the publications.Besides,there was an unprecedented level of close cooperation and information sharing within the global scientific community relative to previous coronavirus research.We combed and drew the knowledge map of the SARS-CoV-2 literature,explored early status of research on etiology,pathology,epidemiology,treatment,prevention,and control,and discussed knowledge gaps that remain to be urgently addressed.Future perspectives on treatment,prevention,and control are also presented to provide fundamental references for current and future coronavirus research.展开更多
Objective:In this study,we aimed to identify the genes involved in leaf margin serration in Perilla frutescens.P.frutescens(Family:Lamiaceae)is widely grown in Asian countries.Perilla leaf is the medicinal part stipul...Objective:In this study,we aimed to identify the genes involved in leaf margin serration in Perilla frutescens.P.frutescens(Family:Lamiaceae)is widely grown in Asian countries.Perilla leaf is the medicinal part stipulated in the Chinese Pharmacopoeia.There are mainly two types of perilla leaves:one with serrated leaf margin which is the phenotype described in the pharmacopoeia and the other with smooth leaf margin.Methods:Transcriptome sequencing,co-expression analysis,and qRT-PCR analysis of six perilla tissues sampled from two different phenotypes(serrated and smooth leaves)were performed.Results:Forty-three differentially expressed genes(DEGs),which may potentially regulate leaf shape,were identified through de novo transcriptome sequencing between the two groups.Genes involved in leaf shape regulation were identified.Simultaneously,we validated five DEGs by qRT-PCR,and the results were consistent with the transcriptome data.In addition,1186 transcription factors(TFs)belonging to 45 TF families were identified.Moreover,the co-expression network of DEGs was constructed.Conclusion:The study identified the key genes that control leaf shape by comparing the transcriptomes.Our findings also provide basic data for further exploring P.frutescens,which can help study the mechanism of leaf shape development and molecular breeding.展开更多
文摘Applying new approaches, methods, and technologies for the estimation of reserves can effectively improve the efficiency and accuracy of assessments of solid mineral resources. After analyzing the development of 3-D geoscience modeling technology （3-D GMT）, this paper discusses the application of 3-D GMT for the estimation of solid mineral reserves, emphatically introducing its workflow and two key technologies, 3-D orebody surface modeling, and property modeling. Moreover, the paper analyzes the limitations of traditional methods, such as the section method and geological block method, and points out the advantages of 3-D GMT： building more accurate 3-D orebody models, expressing the internal inhomogeneous attributes of an orebody, reducing the potential for errors in the estimation of reserves, and implementing dynamic estimations of reserves.
基金supported by the National Natural Science Foundation of China(No.41204094)Science Foundation of China University of Petroleum,Beijing(No.2462015YQ0506)
文摘In this paper, we propose a hybrid PML （H-PML） combining the normal absorption factor of convolutional PML （C-PML） with tangential absorption factor of Mutiaxial PML （M-PML）. The H-PML boundary conditions can better suppress the numerical instability in some extreme models, and the computational speed of finite-element method and the dynamic range are greatly increased using this HPML. We use the finite-element method with a hybrid PML to model the acoustic reflection of the interface when wireline and well logging while drilling （LWD）, in a formation with a reflector outside the borehole. The simulation results suggests that the PS- and SP- reflected waves arrive at the same time when the inclination between the well and the outer interface is zero, and the difference in arrival times increases with increasing dip angle. When there are fractures outside the well, the reflection signal is clearer in the subsequent reflection waves and may be used to identify the fractured zone. The difference between the dominant wavelength and the model scale shows that LWD reflection logging data are of higher resolution and quality than wireline acoustic reflection logging.
基金supported by the National Natural Science Foundation of China (No. 61771062)the Fund of the StateKeyLaboratoryofIPOC(BUPT),China (No. IPOC2018ZT08)。
文摘This paper proposes a hybrid layered asymmetrically clipped optical(HLACO) single-carrier frequency-division multiplexing(SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines layered asymmetrically clipped optical(LACO)-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency-division multiplexing(OFDM)-based dimmable schemes and further enhancing the system performance. Compared to the HLACO-OFDM-based dimming scheme, it obtains a lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit·s^(-1)·Hz^(-1) within the dimming range of 30%–70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.
基金supported by the project: Assessment of economic and social impact of Mobile Broadband in China,which is entrusted by GSM Association in 2011
文摘Increasing popularity of spectrum-based services brings the striking contradictions between the limited spectrum resource and its increasing demands.This paper puts forward an approach to forecast the future spectrum demand and its economic value,so as to offer a scientific basis for spectrum regulators to resolve this contradiction effectively and make a long-term spectrum-use plan.Specifically,this paper analyzes the driving factors of spectrum demand firstly,based on which a forecasting model is constructed to predict the spectrum demand and its deficit/surplus in the next few years.Then,a forecasting model to measure the economic value of spectrum is proposed based on marginal opportunity cost theory,and the indifference curve is introduced to show the economic value generated by additional spectrum.Additionally,an empirical study is conducted to forecast the spectrum demand and its economic value for China in the next 10 years according to the proposed method.The results of this study show that spectrum deficit is a trend in future and releasing additional spectrum will bring China huge economic benefits.
文摘In December 2019,an outbreak of pneumonia,which was named COVID-2019,emerged as a global health crisis.Scientists worldwide are engaged in attempts to elucidate the transmission and pathogenic mechanisms of the causative coronavirus.COVID-19 was declared a pandemic by the World Health Organization in March 2020,making it critical to track and review the state of research on COVID-19 to provide guidance for further investigations.Here,bibliometric and knowledge mapping analyses of studies on COVID-19 were performed,including more than 1,500 papers on COVID-19 available in the PubMed and China National Knowledge Infrastructure databases from January 1,2020 to March 8,2020.In this review,we found that because of the rapid response of researchers worldwide,the number of COVID-19-related publications showed a high growth trend in the first 10 days of February;among these,the largest number of studies originated in China,the country most affected by pandemic in its early stages.Our findings revealed that the epidemic situation and data accessibility of different research teams have caused obvious difference in emphases of the publications.Besides,there was an unprecedented level of close cooperation and information sharing within the global scientific community relative to previous coronavirus research.We combed and drew the knowledge map of the SARS-CoV-2 literature,explored early status of research on etiology,pathology,epidemiology,treatment,prevention,and control,and discussed knowledge gaps that remain to be urgently addressed.Future perspectives on treatment,prevention,and control are also presented to provide fundamental references for current and future coronavirus research.
基金This work was funded by National Natural Science Foundation for regional fund(31860391)Guizhou Province Science and Technology Plan Project(Qian science platform[2019]5656)National Major Project for Breeding New Transgenic Varieties(2016ZX08010-003).
文摘Objective:In this study,we aimed to identify the genes involved in leaf margin serration in Perilla frutescens.P.frutescens(Family:Lamiaceae)is widely grown in Asian countries.Perilla leaf is the medicinal part stipulated in the Chinese Pharmacopoeia.There are mainly two types of perilla leaves:one with serrated leaf margin which is the phenotype described in the pharmacopoeia and the other with smooth leaf margin.Methods:Transcriptome sequencing,co-expression analysis,and qRT-PCR analysis of six perilla tissues sampled from two different phenotypes(serrated and smooth leaves)were performed.Results:Forty-three differentially expressed genes(DEGs),which may potentially regulate leaf shape,were identified through de novo transcriptome sequencing between the two groups.Genes involved in leaf shape regulation were identified.Simultaneously,we validated five DEGs by qRT-PCR,and the results were consistent with the transcriptome data.In addition,1186 transcription factors(TFs)belonging to 45 TF families were identified.Moreover,the co-expression network of DEGs was constructed.Conclusion:The study identified the key genes that control leaf shape by comparing the transcriptomes.Our findings also provide basic data for further exploring P.frutescens,which can help study the mechanism of leaf shape development and molecular breeding.
