It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detec...It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detection statistics are proposed to implement the synchronization and spreading sequence estimation procedure. The proposed algorithm also has a low computational complexity with only linear additions and modifications. Theoretical analysis and simulation results show that the algorithm performs quite well in low SNR environment, and is much better than all the existing typical algorithms with a comprehensive consideration both in performance and computational complexity.展开更多
Background Genotype-by-sequencing has been proposed as an alternative to SNP genotyping arrays in genomic selection to obtain a high density of markers along the genome.It requires a low sequencing depth to be cost ef...Background Genotype-by-sequencing has been proposed as an alternative to SNP genotyping arrays in genomic selection to obtain a high density of markers along the genome.It requires a low sequencing depth to be cost effective,which may increase the error at the genotype assigment.Third generation nanopore sequencing technology offers low cost sequencing and the possibility to detect genome methylation,which provides added value to genotype-by-sequencing.The aim of this study was to evaluate the performance of genotype-by-low pass nanopore sequencing for estimating the direct genomic value in dairy cattle,and the possibility to obtain methylation marks simultaneously.Results Latest nanopore chemistry(LSK14 and Q20)achieved a modal base calling accuracy of 99.55%,whereas previous kit(LSK109)achieved slightly lower accuracy(99.1%).The direct genomic value accuracy from genotype-by-low pass sequencing ranged between 0.79 and 0.99,depending on the trait(milk,fat or protein yield),with a sequencing depth as low as 2×and using the latest chemistry(LSK114).Lower sequencing depth led to biased estimates,yet with high rank correlations.The LSK109 and Q20 achieved lower accuracies(0.57-0.93).More than one million high reliable methylated sites were obtained,even at low sequencing depth,located mainly in distal intergenic(87%)and promoter(5%)regions.Conclusions This study showed that the latest nanopore technology in useful in a LowPass sequencing framework to estimate direct genomic values with high reliability.It may provide advantages in populations with no available SNP chip,or when a large density of markers with a wide range of allele frequencies is needed.In addition,low pass sequencing provided nucleotide methylation status of>1 million nucleotides at≥10×,which is an added value for epigenetic studies.展开更多
In this paper, a new partial transmit sequence(PTS)scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship...In this paper, a new partial transmit sequence(PTS)scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio(PAPR). Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.展开更多
A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity i...A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact(CAI) tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.展开更多
This paper presents a preliminary summary of the applied sequence stratigraphy in nonmarine basins in China. The geological and geophysical data show that the nonmarine sequences mainly resulted from both allocyclic a...This paper presents a preliminary summary of the applied sequence stratigraphy in nonmarine basins in China. The geological and geophysical data show that the nonmarine sequences mainly resulted from both allocyclic and autocyclic processes where the most important factors were isolated tectonics and climate. However, the environmental factor should have been crucial. The depositional base level served as the sea level in the marine environment, while the water table, lake level and fluvial equilibrium were profiled in a terrigenous environment. This accommodation varied periodically with the base level, resulting in the formation of a series of depositional sequences in terms of genesis and space. Basically, the base level of the inner continent was not affected by the changes in the relative sea level. But there would have been some relations between the changes in the relative sea level and that in the continental base level during eustacy flooding. However, a small time lag existed between the changes in the marine basin and the inner continent basin, The lake basin is smaller than the marine basin, but its velocity of sediment supply is greater than that of the marine basin. Therefore, the number of nonmarine sequences is greater than that of marine ones in the same period. It is important to recognize the system tracts for the study of high-precision or high-resolution sequence stratigraphy, especially to analyze the low-stand systems tract with its depositional system. The sequence boundary is genetically characterized by subaerial exposure, stratigraphic truncation and subaqueous erosion. The deposition analysis of Zhanhua depression reveals 5 sequence architectures: alluvial-fluvial/lacustrine architecture, transitional architecture formed between haline (mesohaline) lake and fresh lake, marine duration-deep lacustrine architecture, half deep lacustrine-ramp architecture and fluvial-alluvial plain architecture. During the major development of the nonmarine basin, the step-faulting breaks controlled the depositional system. Usually, the low-stand complex fan, prograding wedge and high-stand turbidity fan were close to the third stepping break. In the low-stand period, the sediments went around the incised valleys which then were filled with sand bar near the second stepping break. At the first stepping break the sediments were bypassed step by step or the alluvial fan was deposited with forced regressions in the low-stand time. The low-stand wedge may serve as favorable subtle or complex traps at the basin floor fan. The economic effectiveness is measured with the borehole in Bohai Bay basin.展开更多
A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorit...A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorithm have good performance in uniformity, correlation, complexity and security.A high-speed, low-power and low-cost ASIC of FH sequences generator is implemented by optimizing the structure of S-Box and MixColumns of AES algorithm, proposing a hierarchical power management strategy, and applying the dynamic clock gating technology based on finite state machine and clock gating.SMIC 0.18 μm standard CMOS technology shows that the scale of ASIC is only about 10.68 kgate, power consumption is 33.8 μW/MHz, and the maximum hop-rate is 1 098 901 hop/s.This design is suitable for portable FH communication system for its advantages in high-security and hop-rate, low-power and low-cost.The proposed FH sequences generator has been employed in Bluetooth SoC design.展开更多
In this paper, based on the results of tomographic image of Tangshan and Xingtai areas, the relations between thecharacteristics of the two strong earthquake sequences and their three-dimensional velocity structures a...In this paper, based on the results of tomographic image of Tangshan and Xingtai areas, the relations between thecharacteristics of the two strong earthquake sequences and their three-dimensional velocity structures are studied.The research results indicate that:① Mosaic distribution of low-velocity bodies and high-velocity bodies, especially the existence of high-velocity bodies with large size in crust are the common basis of development of thetwo earthquake sequences. ② Scale, depth, and heterogeneity of high-velocity and low-velocity bodies are theimportant factors to effect the characteristic of earthquake sequences. ③ The depth of the high-velocity body inTangshan area is less than that in Xingtai area, which is the principal reason why the dominant focal depth and thebiggest focal depth of Tangshan earthquake sequence are less than Xingtai's. ④ The depth of the high-velocitybodies in Ninghe area is more than that in Tangshan-Luanxian area, which lead to the biggest magnitude and epicentral intensity are lower. These results could be helpful for predicting the main shock of strong swarm-typeearthquakes and later strong aftershocks.展开更多
In the subtribe Maydeae, Tripsacum and Zea are closely related genera. Tripsacum is a horticultural crop widely used as pasture forage. Previous studies suggested that Tripsacum might play an important role in maize o...In the subtribe Maydeae, Tripsacum and Zea are closely related genera. Tripsacum is a horticultural crop widely used as pasture forage. Previous studies suggested that Tripsacum might play an important role in maize origin and evolution. However, our understanding of the genomics and the evolution of Tripsacum remains limited. In this study, two diploids,T. dactyloides var. meridionale(2n = 36, MR) and T. dactyloides(2n = 36, DD), and one tetraploid,T. dactyloides(2n = 72, DL) were sequenced by low-coverage genome sequencing followed by graph-based cluster analysis. The results showed that 63.23%, 59.20%, and 61.57% of the respective genome of MR, DD, and DL were repetitive DNA sequence. The proportions of different repetitive sequences varied greatly among the three species. Fluorescence in situ hybridization(FISH) analysis of mitotic metaphase chromosomes with satellite repeats as the probes showed that the FISH signal patterns of DL were more similar to that of DD than to that of MR. Comparative analysis of the repeats also showed that DL shared more common repeat families with DD than with MR. Phylogenetic analysis of internal transcribed spacer region sequences further supported the evolutionary relationship among the three species. Repetitive sequences comparison showed that Tripsacum shared more repeat families with Zea than with Coix and Sorghum. Our study sheds new light on the genomics of Tripsacum and differential speciation in the Poaceae family.展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education (20060003032)
文摘It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detection statistics are proposed to implement the synchronization and spreading sequence estimation procedure. The proposed algorithm also has a low computational complexity with only linear additions and modifications. Theoretical analysis and simulation results show that the algorithm performs quite well in low SNR environment, and is much better than all the existing typical algorithms with a comprehensive consideration both in performance and computational complexity.
文摘Background Genotype-by-sequencing has been proposed as an alternative to SNP genotyping arrays in genomic selection to obtain a high density of markers along the genome.It requires a low sequencing depth to be cost effective,which may increase the error at the genotype assigment.Third generation nanopore sequencing technology offers low cost sequencing and the possibility to detect genome methylation,which provides added value to genotype-by-sequencing.The aim of this study was to evaluate the performance of genotype-by-low pass nanopore sequencing for estimating the direct genomic value in dairy cattle,and the possibility to obtain methylation marks simultaneously.Results Latest nanopore chemistry(LSK14 and Q20)achieved a modal base calling accuracy of 99.55%,whereas previous kit(LSK109)achieved slightly lower accuracy(99.1%).The direct genomic value accuracy from genotype-by-low pass sequencing ranged between 0.79 and 0.99,depending on the trait(milk,fat or protein yield),with a sequencing depth as low as 2×and using the latest chemistry(LSK114).Lower sequencing depth led to biased estimates,yet with high rank correlations.The LSK109 and Q20 achieved lower accuracies(0.57-0.93).More than one million high reliable methylated sites were obtained,even at low sequencing depth,located mainly in distal intergenic(87%)and promoter(5%)regions.Conclusions This study showed that the latest nanopore technology in useful in a LowPass sequencing framework to estimate direct genomic values with high reliability.It may provide advantages in populations with no available SNP chip,or when a large density of markers with a wide range of allele frequencies is needed.In addition,low pass sequencing provided nucleotide methylation status of>1 million nucleotides at≥10×,which is an added value for epigenetic studies.
基金supported by the National Natural Science Foundation of China(6167309361370152)the Science and Technology Project of Shenyang(F16-205-1-01)
文摘In this paper, a new partial transmit sequence(PTS)scheme with low computational complexity is proposed for the problems of high computational complexity in the conventional PTS method. By analyzing the relationship of candidate sequences in the PTS method under the interleaved partition method, it has been discovered that some candidate sequences generated by phase factor sequences have the same peak average power ratio(PAPR). Hence, phase factor sequences can be optimized to reduce their searching times. Then, the computational process of generating candidate sequences can be simplified by improving the utilization of data and minimizing the calculations of complex multiplication. The performance analysis shows that, compared with the conventional PTS scheme, the proposed approach significantly decreases the computational complexity and has no loss of PAPR performance.
基金Funded by the National Natural Science Foundation of China(No.51275393)the Fundamental Research Funds for the Central Universities(No.xjj2017160)
文摘A method to improve the low-velocity impact performance of composite laminate is proposed, and a multi-island genetic algorithm is used for the optimization of composite laminate stacking sequence under low-velocity impact loads based on a 2D dynamic impact finite element analysis. Low-velocity impact tests and compression-after impact(CAI) tests have been conducted to verify the effectiveness of optimization method. Experimental results show that the impact damage areas of the optimized laminate have been reduced by 42.1% compared to the baseline specimen, and the residual compression strength has been increased by 10.79%, from baseline specimen 156.97 MPa to optimized 173.91 MPa. The tests result shows that optimization method can effectively enhance the impact performances of the laminate.
基金This paper is supported by "211" item of new techniquetheory for fossil fuel exploration.
文摘This paper presents a preliminary summary of the applied sequence stratigraphy in nonmarine basins in China. The geological and geophysical data show that the nonmarine sequences mainly resulted from both allocyclic and autocyclic processes where the most important factors were isolated tectonics and climate. However, the environmental factor should have been crucial. The depositional base level served as the sea level in the marine environment, while the water table, lake level and fluvial equilibrium were profiled in a terrigenous environment. This accommodation varied periodically with the base level, resulting in the formation of a series of depositional sequences in terms of genesis and space. Basically, the base level of the inner continent was not affected by the changes in the relative sea level. But there would have been some relations between the changes in the relative sea level and that in the continental base level during eustacy flooding. However, a small time lag existed between the changes in the marine basin and the inner continent basin, The lake basin is smaller than the marine basin, but its velocity of sediment supply is greater than that of the marine basin. Therefore, the number of nonmarine sequences is greater than that of marine ones in the same period. It is important to recognize the system tracts for the study of high-precision or high-resolution sequence stratigraphy, especially to analyze the low-stand systems tract with its depositional system. The sequence boundary is genetically characterized by subaerial exposure, stratigraphic truncation and subaqueous erosion. The deposition analysis of Zhanhua depression reveals 5 sequence architectures: alluvial-fluvial/lacustrine architecture, transitional architecture formed between haline (mesohaline) lake and fresh lake, marine duration-deep lacustrine architecture, half deep lacustrine-ramp architecture and fluvial-alluvial plain architecture. During the major development of the nonmarine basin, the step-faulting breaks controlled the depositional system. Usually, the low-stand complex fan, prograding wedge and high-stand turbidity fan were close to the third stepping break. In the low-stand period, the sediments went around the incised valleys which then were filled with sand bar near the second stepping break. At the first stepping break the sediments were bypassed step by step or the alluvial fan was deposited with forced regressions in the low-stand time. The low-stand wedge may serve as favorable subtle or complex traps at the basin floor fan. The economic effectiveness is measured with the borehole in Bohai Bay basin.
基金Supported by National Natural Science Foundation of China (No.60676053)
文摘A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorithm have good performance in uniformity, correlation, complexity and security.A high-speed, low-power and low-cost ASIC of FH sequences generator is implemented by optimizing the structure of S-Box and MixColumns of AES algorithm, proposing a hierarchical power management strategy, and applying the dynamic clock gating technology based on finite state machine and clock gating.SMIC 0.18 μm standard CMOS technology shows that the scale of ASIC is only about 10.68 kgate, power consumption is 33.8 μW/MHz, and the maximum hop-rate is 1 098 901 hop/s.This design is suitable for portable FH communication system for its advantages in high-security and hop-rate, low-power and low-cost.The proposed FH sequences generator has been employed in Bluetooth SoC design.
文摘In this paper, based on the results of tomographic image of Tangshan and Xingtai areas, the relations between thecharacteristics of the two strong earthquake sequences and their three-dimensional velocity structures are studied.The research results indicate that:① Mosaic distribution of low-velocity bodies and high-velocity bodies, especially the existence of high-velocity bodies with large size in crust are the common basis of development of thetwo earthquake sequences. ② Scale, depth, and heterogeneity of high-velocity and low-velocity bodies are theimportant factors to effect the characteristic of earthquake sequences. ③ The depth of the high-velocity body inTangshan area is less than that in Xingtai area, which is the principal reason why the dominant focal depth and thebiggest focal depth of Tangshan earthquake sequence are less than Xingtai's. ④ The depth of the high-velocitybodies in Ninghe area is more than that in Tangshan-Luanxian area, which lead to the biggest magnitude and epicentral intensity are lower. These results could be helpful for predicting the main shock of strong swarm-typeearthquakes and later strong aftershocks.
基金supported by the National Natural Science Foundation of China (Nos. 31471499, 91535206)
文摘In the subtribe Maydeae, Tripsacum and Zea are closely related genera. Tripsacum is a horticultural crop widely used as pasture forage. Previous studies suggested that Tripsacum might play an important role in maize origin and evolution. However, our understanding of the genomics and the evolution of Tripsacum remains limited. In this study, two diploids,T. dactyloides var. meridionale(2n = 36, MR) and T. dactyloides(2n = 36, DD), and one tetraploid,T. dactyloides(2n = 72, DL) were sequenced by low-coverage genome sequencing followed by graph-based cluster analysis. The results showed that 63.23%, 59.20%, and 61.57% of the respective genome of MR, DD, and DL were repetitive DNA sequence. The proportions of different repetitive sequences varied greatly among the three species. Fluorescence in situ hybridization(FISH) analysis of mitotic metaphase chromosomes with satellite repeats as the probes showed that the FISH signal patterns of DL were more similar to that of DD than to that of MR. Comparative analysis of the repeats also showed that DL shared more common repeat families with DD than with MR. Phylogenetic analysis of internal transcribed spacer region sequences further supported the evolutionary relationship among the three species. Repetitive sequences comparison showed that Tripsacum shared more repeat families with Zea than with Coix and Sorghum. Our study sheds new light on the genomics of Tripsacum and differential speciation in the Poaceae family.