The characterization of long-range correlations and fractal properties of DNA sequences has proved to be adifficult though rewarding task mainly due to the mosaic character of DNA consisting of many patches of various...The characterization of long-range correlations and fractal properties of DNA sequences has proved to be adifficult though rewarding task mainly due to the mosaic character of DNA consisting of many patches of various lengthswith different nucleotide constitutions.In this paper we investigate statistical correlations among different positions in DNAsequences using the two-dimensional DNA walk.The root-mean-square fluctuation F(l)is described by a power law.Theautocorrelation function C(l),which is used to measure the linear dependence and periodicity,exists a power law ofC(l)-l^(-μ).We also calculate the mean-square distance<R^2(l)>along the DNA chain,and it may be expressed as<R^2(l)>-l^(?)with 2>γ>1.Our investigations can provide some insights into long-range correlations in DNA sequences.展开更多
New classes of real sequences with good auto-correlation and cross-correlation areconstructed by using sinusoidal functions. The new sequences are better than the FZC and Alltopsequences in two aspects: (1) lower corr...New classes of real sequences with good auto-correlation and cross-correlation areconstructed by using sinusoidal functions. The new sequences are better than the FZC and Alltopsequences in two aspects: (1) lower correlations and (2) taking real values. The new sequencescan be used in many areas.展开更多
Using continuous wavelet transform as the analytical tool, the fractal characteristic of nucleotide sequences was studied. The fractal dimension of the exon and intron sequences for different species was calculated. ...Using continuous wavelet transform as the analytical tool, the fractal characteristic of nucleotide sequences was studied. The fractal dimension of the exon and intron sequences for different species was calculated. We use the Mexican hat wavelet function as the mother wavelet and Hurst exponent to describe the long-range correlation. It is found that the Hurst exponent of intron sequence is larger than that of exon sequence for the same gene.展开更多
The minimum aperiodic crosscorrelation of binary sequences of size M and length n over the alphabet E={1, -1} has been obtained by Levenshtein for M≥4 and n≥2 These bounds improve a long standing bound giv...The minimum aperiodic crosscorrelation of binary sequences of size M and length n over the alphabet E={1, -1} has been obtained by Levenshtein for M≥4 and n≥2 These bounds improve a long standing bound given by Welch. In this paper, the Sarwate bounds for codes over the p th roots of unity with the same parameters M and n are discussed, that is,the lower bounds and trade off are established for the maximum magnitude of the aperiodic crosscorrelation function and the maximum magnitude of the out of phase aperiodic autocorrelation function for the sets of periodic sequences with the same parameters M and n by using the modified Levenshtein method. The results show that new bounds are tighter than Sarwate bounds and Levenshtein bounds.展开更多
Based on a class of bipolar sequences with two-values autocorrelation functions, a new family of bipolar sequences is constructed and its correlation spectrum is calculated. It is shown that the new family is optimal ...Based on a class of bipolar sequences with two-values autocorrelation functions, a new family of bipolar sequences is constructed and its correlation spectrum is calculated. It is shown that the new family is optimal with respect to Welch's bound and is different from the small set of Kasami sequences, while both of them have the same correlation properties.展开更多
The source parameters of the Yingjiang earthquake sequences in 2008 are obtained by applying spectral analysis and Brunes source model,based on the digital waveform data recorded by the Yunnan Digital Seismic Network....The source parameters of the Yingjiang earthquake sequences in 2008 are obtained by applying spectral analysis and Brunes source model,based on the digital waveform data recorded by the Yunnan Digital Seismic Network.The correlation coefficients are calculated using the low-frequency spectral amplitudes of 2 events recorded by a same station,then,events with similar focal mechanism are grouped using the clustering analysis method.Compared to the obtained focal mechanisms,it is found that there are good correlations with the azimuth of P axes in each clustering group,and the larger the correlation coefficient,the closer the azimuths of P axes.We divide the Yingjiang area into 3 regions to analyze the stress level and stress direction by combining the source parameters and the mean focal mechanism of each group.The results show:The change and transformation of the focal mechanism types at different stages can represent the temporal characteristics of the regional stress field.If the earthquake focal mechanism types are concentrated in a time period and switch to the direction of regional stress field,it may be a sign of strong earthquake.There is some relationship between the stress drop and the type of focal mechanism.Those earthquakes with stress fields revealed by focal mechanism types closer to the regional tectonic stress field will have higher stress drop,while those with the focal mechanism-revealed stress fields differing a lot from the regional tectonic stress field will generally have a lower stress drop.展开更多
This paper presents lab-scale experiment carried out to evaluate the correlation between ammonia nitrogen (NH3-N) and p-toluidine using sequencing batch reactor treating synthetic p-toluidine wastewater. The profile...This paper presents lab-scale experiment carried out to evaluate the correlation between ammonia nitrogen (NH3-N) and p-toluidine using sequencing batch reactor treating synthetic p-toluidine wastewater. The profiles of NH3-N and p-toluidine were traced under the concentration of sucrose in the influent varied from 0 to 500 mg/L, aerated airflow varied from 0.6 to 1.2 L/min and temperature varied from 10 to 25℃, respectively. The results showed that the concentration of NH3-N turned from increase to decrease when p-toluidine was nearly completely biodegraded, so the profile of NH3-N could clearly indicate the endpoint of p-toluidine biodegradation. And the profile of NH3-N was not influenced by the sucrose in the influent, aerated airflow and temperature. It is showed that using ammonia nitrogen as monitoring and control parameter is feasible and reliable and has promising application in amine wastewater treatment by SBR.展开更多
Based on the analysis of well logs, seismic data, core studies, the Dongying (东营) Formation along the nearshore and adjacent sea areas, Bohai (渤海) Bay basin has been subdivided into three third-order sequences...Based on the analysis of well logs, seismic data, core studies, the Dongying (东营) Formation along the nearshore and adjacent sea areas, Bohai (渤海) Bay basin has been subdivided into three third-order sequences from base to top: namely, sequences SQ1, SQ2 and SQ3. The three sequences have different wireline (SP) log responses, showing triple-section characteristics with SQ1 being characterized by primarily flat baseline with intercalation of relatively low spontaneous potential, SQ2 generally exhibiting weak or moderate amplitude spontaneous potential with finger-shaped peaks, and SQ3 having relatively high spontaneous potential with funnel-shaped log curves. On the basis of the triple-section characteristics, the stratigraphic sequences can be correlated consistently throughout the entire study area. A stratigraphic and sedimentary model for sequences SQ1 to SQ3 of the Dongying Formation in the study area has been proposed. The accommodation space change in the two sides of the asymmetrical basin was examined and the asymmetrical basin has the feature of the asymmetrical accommodation space change. The asymmetrical physiography is a vital factor to influence the accommodation changes in additional to the lake level change, tectonism and sediment supply. This may have important implications to similar basins in other parts of China or elsewhere.展开更多
The precise correlation of the Ordovician successions in different facies is difficult due to the complex changes of the tecto-paleogeography in South China.Based on previous studies,the authors recognized 103rd grade...The precise correlation of the Ordovician successions in different facies is difficult due to the complex changes of the tecto-paleogeography in South China.Based on previous studies,the authors recognized 103rd grade sequences,i.e.,Osq1 to Osq10 in ascending order,by the integrated study of chronostratigraphy,biostratigraphy as well as the analysis on the sedimentary facies.The authors are confident to correlate the Ordovician successions precisely in different facies in an isochronous stratigraphic framework with the application of the method of sequence stratigraphy and correlation.展开更多
In this paper,a new class of almost binary sequence pair with a single zero element is presented.The almost binary sequence pairs with three-level correlation are constructed based on cyclotomic numbers of order 2,4,a...In this paper,a new class of almost binary sequence pair with a single zero element is presented.The almost binary sequence pairs with three-level correlation are constructed based on cyclotomic numbers of order 2,4,and 6.Most of them have good correlation and balance property,whose maximum nontrivial correlation magnitudes are 2 and the difference between the numbers of occurrence of +1's and-1's are 0 or 1.In addition,the corresponding binary sequence pairs are investigated as well and we can also get some kinds of binary sequence pairs with optimum balance and good correlation.展开更多
It is dominantly characterized that arc and back\|arc basin occur mutually in arc\|basin systems, Jomda arc and Sinda back\|arc basin located in Qamdo area are typical(Fig.1). Jomda arc covered by Triassic with thickn...It is dominantly characterized that arc and back\|arc basin occur mutually in arc\|basin systems, Jomda arc and Sinda back\|arc basin located in Qamdo area are typical(Fig.1). Jomda arc covered by Triassic with thickness about 10000m.Marine sediments predominate, and are Characterized by the largely thick turbidity rocks and arc volcanic rocks of calc\|alkali suite which frequent volcanic events raised. Sinda back\|arc basin with a land\|crust basement is filled by the Upper Triassic sedimentary strata of more than 5000m. The active marginal sediments are composed of terrigenous,basinal and volcanic turbidity deposits of bathyal to deep\|sea facies,Characteristic extensive alkali basalts and submarine spout hot water deposits. Based on investigation of the cutcrop pro\|file, isotime grillwork for Triassic sequence stratigraphy has been established. for example Jomda arc basin, including 6 type 1 and 4 type 2 boundaries.10 three\|order sequences are divided, including 6 type 1 and 4 type 2 sequences. These sequences evolves during 37Ma,the estimated average time of a sequences is 3~7Ma,with being generally 1~2Ma,the longest being about 10Ma. type 1 and type 2 sequence boundaries are identified, in Upper Triassic Sinda back\|arc basin two type 1 and one type 2 sequences are divided. Relations have been first concluded among mainly controlled factors of sequence stratigraphies in arc and back\|arc basin systems. First, more sequences product and three\|units of its structures are complete in arc systems of complicated tectonic\|volcanic topographies, for example Jomda arc area of island\|sea framework, because lots of deposits are supplied and accumulations are allowed. Secondly, tectonic control is very clear, type 1 boundaries of SQ1 and SQ7 are clearly unconformity interfaces stressed by tectonism.Thirdly,volcanic rocks is greatly related with sequences, and there are various volcanic rocks in mang sequences,for example Jomda sequence stratigraphies,volcanic rocks of calc alkaline suite occurs in LST which thickness occupying in LST is middle; both tholeiite and calc\|alkaline,alkaline suite (Sinda back\|arc area) in TST, thickness smallest; calc\|alkaline suite in HST, Thickness biggest. It proves that intra\|genetic association between volcanic and relative sea\|level changes, which is gained by the concordance of thick curves of volcanic rock and sea\|level in different systematic traces. When thickness of volcanic rocks growing or progressing, relative sea\|level falls; otherwise, when reducing, it rises. There are larger differences in quantities, structures and types of sequences by comparing sequence stratigraphies of arc, back\|arc with craton area. Those varieties are responses for interactions among tectonic\|volcano, sediment and eustacy. It is pointed out that tectonic and arc volcanic processes are crucial.展开更多
The optimal design of training sequences for channel estimation in multiple-input multiple-output (MIMO) systems under spatially correlated fading is considered. The channel is assumed to be a block-fading model wit...The optimal design of training sequences for channel estimation in multiple-input multiple-output (MIMO) systems under spatially correlated fading is considered. The channel is assumed to be a block-fading model with spatial correlation known at both the transmitter and the receiver. To minimize the channel estimation error, optimal training sequences are designed to exploit full information of the spatial correlation under the criterion of minimum mean square error (MMSE). It is investigated that the spatial correlation is helpful to decrease the estimation error and the proposed training sequences have good performance via simulations.展开更多
The group correlation properties of binary sequences is studied, and a conclusion is drawn that not only the group correlation function of a binary sequence itself is ideal, but also some of its subsets, which code le...The group correlation properties of binary sequences is studied, and a conclusion is drawn that not only the group correlation function of a binary sequence itself is ideal, but also some of its subsets, which code length N is even, is ideal. Finally a general formula of the group correlation of a binary sequence set is derived.展开更多
In this paper we propose a new class of ternary Zero Correlation Zone (ZCZ) sequence sets based on binary ZCZ sequence sets construction. It is shown that the proposed ternary ZCZ sequence sets can reach the upper bou...In this paper we propose a new class of ternary Zero Correlation Zone (ZCZ) sequence sets based on binary ZCZ sequence sets construction. It is shown that the proposed ternary ZCZ sequence sets can reach the upper bound on the ZCZ sequences. The performance of the proposed sequences set in asynchronous Direct Sequence-Code Division Multiple Access (DS-CDMA) system is evaluated. In the simulation we used two types of channels: Additive White Gaussian Noise (AWGN) and frequency non-selective fading with AWGN noise. The proposed ternary ZCZ sequence sets show better results, in term of Bit Error Rate (BER), than Hayashi’s ternary ZCZ sequence sets.展开更多
The phase change of lacustrine gravity flow deposition is fast and complex. In its reservoir division and correlation, the isochronous problem is very important. Taking the oil formation I of Es3 in Wuhaozhuang oilfie...The phase change of lacustrine gravity flow deposition is fast and complex. In its reservoir division and correlation, the isochronous problem is very important. Taking the oil formation I of Es3 in Wuhaozhuang oilfield as an example, through the analysis of stratigraphic drilling and logging data in the study area, according to the genetic types of different levels of base level cycle interfaces and the characteristics of high-resolution sequence stratigraphy, this paper subdivides the lacustrine gravity flow oil layer of lower Es3 in Wuhaozhuang Oilfield, divides it into four short-term base level cycle sequences, and establishes the high-resolution isochronous stratigraphic framework of this interval. It is found that the mid-term, short-term and ultra short-term base level cycles correspond to the oil formation, sand layer group and single layer in the oil layer correlation unit of the oilfield respectively. Based on this, the oil layer correlation unit of the interval is divided, and the sublayer correlation model is established according to the identification characteristics of the short-term base level cycle.展开更多
To consider the infl uence of aftershocks in engineering design, the correlations between main shocks and aftershocks should be examined, and an aftershock simulation method with main shock ground motions needs to be ...To consider the infl uence of aftershocks in engineering design, the correlations between main shocks and aftershocks should be examined, and an aftershock simulation method with main shock ground motions needs to be developed. In this study, the data on the sequences of main shock–aftershock ground motions and other related parameters were collected. Using these data, correlations between the magnitude, frequency, duration and energy of the main shock–aftershock ground motions were investigated. The results showed that the magnitude of the aftershock can be larger than that of the main shock. The shapes of the Fourier amplitude spectra of main shocks and aftershocks were similar;however, the predominant frequency and high-frequency components of the aftershock tended to be larger. Considering the magnitude diff erence between the main shock and the aftershock, the correlation of durations was explored. Additionally, a new concept, the duration ratio, was defi ned to describe the concentration of seismic energy release, and main shock energy was strongly positively correlated with the energy attenuated during the main shock–aftershock sequence. Finally, based on these results regarding correlation, an aftershock synthesis using recorded main shock ground motions was constructed with the trigonometric series method for seismic design, and some examples are given to analyze the rationality of this synthetic method.展开更多
In this paper,a property of Frequency Hopping (FH) sequence set with No Hit Zone (NHZ) is analyzed. Based on matrix transform and mapping methods,respectively,two classes of NHZ FH sequences are presented. These NHZ F...In this paper,a property of Frequency Hopping (FH) sequence set with No Hit Zone (NHZ) is analyzed. Based on matrix transform and mapping methods,respectively,two classes of NHZ FH sequences are presented. These NHZ FH sequences have good Hamming auto-correlation and Hamming cross-correlation properties. FH Code-Division Multiple Access (FH-CDMA) communication systems employing such NHZ FH sequences will eliminate multiple-access interference if the maximum time delay is shorter than the length of the NHZ.展开更多
With the continuous development of network technology,various large-scale cyber-attacks continue to emerge.These attacks pose a severe threat to the security of systems,networks,and data.Therefore,how to mine attack p...With the continuous development of network technology,various large-scale cyber-attacks continue to emerge.These attacks pose a severe threat to the security of systems,networks,and data.Therefore,how to mine attack patterns from massive data and detect attacks are urgent problems.In this paper,an approach for attack mining and detection is proposed that performs tasks of alarm correlation,false-positive elimination,attack mining,and attack prediction.Based on the idea of CluStream,the proposed approach implements a flow clustering method and a two-step algorithm that guarantees efficient streaming and clustering.The context of an alarm in the attack chain is analyzed and the LightGBM method is used to perform falsepositive recognition with high accuracy.To accelerate the search for the filtered alarm sequence data to mine attack patterns,the PrefixSpan algorithm is also updated in the store strategy.The updated PrefixSpan increases the processing efficiency and achieves a better result than the original one in experiments.With Bayesian theory,the transition probability for the sequence pattern string is calculated and the alarm transition probability table constructed to draw the attack graph.Finally,a long-short-term memory network and embedding word-vector method are used to perform online prediction.Results of numerical experiments show that the method proposed in this paper has a strong practical value for attack detection and prediction.展开更多
Speedometer identification has been researched for many years.The common approaches to that problem are usually based on image subtraction,which does not adapt to image offsets caused by camera vibration.To cope with ...Speedometer identification has been researched for many years.The common approaches to that problem are usually based on image subtraction,which does not adapt to image offsets caused by camera vibration.To cope with the rapidity,robust and accurate requirements of this kind of work in dynamic scene,a fast speedometer identification algorithm is proposed,it utilizes phase correlation method based on regional entire template translation to estimate the offset between images.In order to effectively reduce unnecessary computation and false detection rate,an improved linear Hough transform method with two optimization strategies is presented for pointer line detection.Based on VC++ 6.0 software platform with OpenCV library,the algorithm performance under experiments has shown that it celerity and precision.展开更多
In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interfer...In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interference (MAI), but also support flexible number of users com- pared with system using Orthogonal Complementary (OC) codes. Multicarrier DS-CDMA using OC codes can be regarded as a special case of our proposed system. Zero Correlation Zone (ZCZ) of ZCS can be flexibly adjusted to meet the requirements on the user number and maximum multipath and in- ter-user delay, in this way, more users can be supported without losing interference-free property. The effectiveness of the proposed system is validated through theoretical analysis and simulation results.展开更多
基金This work was financially support by the National Natural Science Foundation of China(Nos.29874012,20174036,20274040)Natural Science Foundation of Zhejiang Province(No.10102).
文摘The characterization of long-range correlations and fractal properties of DNA sequences has proved to be adifficult though rewarding task mainly due to the mosaic character of DNA consisting of many patches of various lengthswith different nucleotide constitutions.In this paper we investigate statistical correlations among different positions in DNAsequences using the two-dimensional DNA walk.The root-mean-square fluctuation F(l)is described by a power law.Theautocorrelation function C(l),which is used to measure the linear dependence and periodicity,exists a power law ofC(l)-l^(-μ).We also calculate the mean-square distance<R^2(l)>along the DNA chain,and it may be expressed as<R^2(l)>-l^(?)with 2>γ>1.Our investigations can provide some insights into long-range correlations in DNA sequences.
基金Project supported by The National Nature Science Fund for youth
文摘New classes of real sequences with good auto-correlation and cross-correlation areconstructed by using sinusoidal functions. The new sequences are better than the FZC and Alltopsequences in two aspects: (1) lower correlations and (2) taking real values. The new sequencescan be used in many areas.
基金This work was supported by the Provincial Natural Science Foundation of Guangdong(Contract 990944)the National Natural Science Foundation of China(Contract 20205003,29975033).
文摘Using continuous wavelet transform as the analytical tool, the fractal characteristic of nucleotide sequences was studied. The fractal dimension of the exon and intron sequences for different species was calculated. We use the Mexican hat wavelet function as the mother wavelet and Hurst exponent to describe the long-range correlation. It is found that the Hurst exponent of intron sequence is larger than that of exon sequence for the same gene.
文摘The minimum aperiodic crosscorrelation of binary sequences of size M and length n over the alphabet E={1, -1} has been obtained by Levenshtein for M≥4 and n≥2 These bounds improve a long standing bound given by Welch. In this paper, the Sarwate bounds for codes over the p th roots of unity with the same parameters M and n are discussed, that is,the lower bounds and trade off are established for the maximum magnitude of the aperiodic crosscorrelation function and the maximum magnitude of the out of phase aperiodic autocorrelation function for the sets of periodic sequences with the same parameters M and n by using the modified Levenshtein method. The results show that new bounds are tighter than Sarwate bounds and Levenshtein bounds.
文摘Based on a class of bipolar sequences with two-values autocorrelation functions, a new family of bipolar sequences is constructed and its correlation spectrum is calculated. It is shown that the new family is optimal with respect to Welch's bound and is different from the small set of Kasami sequences, while both of them have the same correlation properties.
基金funded under the National Science and Technology Support Program of the 12th "Five-year Plan",China(2012BAK19B02)
文摘The source parameters of the Yingjiang earthquake sequences in 2008 are obtained by applying spectral analysis and Brunes source model,based on the digital waveform data recorded by the Yunnan Digital Seismic Network.The correlation coefficients are calculated using the low-frequency spectral amplitudes of 2 events recorded by a same station,then,events with similar focal mechanism are grouped using the clustering analysis method.Compared to the obtained focal mechanisms,it is found that there are good correlations with the azimuth of P axes in each clustering group,and the larger the correlation coefficient,the closer the azimuths of P axes.We divide the Yingjiang area into 3 regions to analyze the stress level and stress direction by combining the source parameters and the mean focal mechanism of each group.The results show:The change and transformation of the focal mechanism types at different stages can represent the temporal characteristics of the regional stress field.If the earthquake focal mechanism types are concentrated in a time period and switch to the direction of regional stress field,it may be a sign of strong earthquake.There is some relationship between the stress drop and the type of focal mechanism.Those earthquakes with stress fields revealed by focal mechanism types closer to the regional tectonic stress field will have higher stress drop,while those with the focal mechanism-revealed stress fields differing a lot from the regional tectonic stress field will generally have a lower stress drop.
文摘This paper presents lab-scale experiment carried out to evaluate the correlation between ammonia nitrogen (NH3-N) and p-toluidine using sequencing batch reactor treating synthetic p-toluidine wastewater. The profiles of NH3-N and p-toluidine were traced under the concentration of sucrose in the influent varied from 0 to 500 mg/L, aerated airflow varied from 0.6 to 1.2 L/min and temperature varied from 10 to 25℃, respectively. The results showed that the concentration of NH3-N turned from increase to decrease when p-toluidine was nearly completely biodegraded, so the profile of NH3-N could clearly indicate the endpoint of p-toluidine biodegradation. And the profile of NH3-N was not influenced by the sucrose in the influent, aerated airflow and temperature. It is showed that using ammonia nitrogen as monitoring and control parameter is feasible and reliable and has promising application in amine wastewater treatment by SBR.
基金the National Natural ScienceFoundation of China (No. 40702024)the Research Instituteof Petroleum Exploration and Development (RIPED),PetroChina
文摘Based on the analysis of well logs, seismic data, core studies, the Dongying (东营) Formation along the nearshore and adjacent sea areas, Bohai (渤海) Bay basin has been subdivided into three third-order sequences from base to top: namely, sequences SQ1, SQ2 and SQ3. The three sequences have different wireline (SP) log responses, showing triple-section characteristics with SQ1 being characterized by primarily flat baseline with intercalation of relatively low spontaneous potential, SQ2 generally exhibiting weak or moderate amplitude spontaneous potential with finger-shaped peaks, and SQ3 having relatively high spontaneous potential with funnel-shaped log curves. On the basis of the triple-section characteristics, the stratigraphic sequences can be correlated consistently throughout the entire study area. A stratigraphic and sedimentary model for sequences SQ1 to SQ3 of the Dongying Formation in the study area has been proposed. The accommodation space change in the two sides of the asymmetrical basin was examined and the asymmetrical basin has the feature of the asymmetrical accommodation space change. The asymmetrical physiography is a vital factor to influence the accommodation changes in additional to the lake level change, tectonism and sediment supply. This may have important implications to similar basins in other parts of China or elsewhere.
基金the Natural Science Foundation of China (41472031)the Gelogical Survey of China (121201009000172111, 121201009000150017)a contribution to the IGCP Project 591, The Early to Middle Paleozoic Revolution.
文摘The precise correlation of the Ordovician successions in different facies is difficult due to the complex changes of the tecto-paleogeography in South China.Based on previous studies,the authors recognized 103rd grade sequences,i.e.,Osq1 to Osq10 in ascending order,by the integrated study of chronostratigraphy,biostratigraphy as well as the analysis on the sedimentary facies.The authors are confident to correlate the Ordovician successions precisely in different facies in an isochronous stratigraphic framework with the application of the method of sequence stratigraphy and correlation.
基金Supported by the National Natural Science Foundation of China (No. 60872061,60971126,and 61172094)
文摘In this paper,a new class of almost binary sequence pair with a single zero element is presented.The almost binary sequence pairs with three-level correlation are constructed based on cyclotomic numbers of order 2,4,and 6.Most of them have good correlation and balance property,whose maximum nontrivial correlation magnitudes are 2 and the difference between the numbers of occurrence of +1's and-1's are 0 or 1.In addition,the corresponding binary sequence pairs are investigated as well and we can also get some kinds of binary sequence pairs with optimum balance and good correlation.
文摘It is dominantly characterized that arc and back\|arc basin occur mutually in arc\|basin systems, Jomda arc and Sinda back\|arc basin located in Qamdo area are typical(Fig.1). Jomda arc covered by Triassic with thickness about 10000m.Marine sediments predominate, and are Characterized by the largely thick turbidity rocks and arc volcanic rocks of calc\|alkali suite which frequent volcanic events raised. Sinda back\|arc basin with a land\|crust basement is filled by the Upper Triassic sedimentary strata of more than 5000m. The active marginal sediments are composed of terrigenous,basinal and volcanic turbidity deposits of bathyal to deep\|sea facies,Characteristic extensive alkali basalts and submarine spout hot water deposits. Based on investigation of the cutcrop pro\|file, isotime grillwork for Triassic sequence stratigraphy has been established. for example Jomda arc basin, including 6 type 1 and 4 type 2 boundaries.10 three\|order sequences are divided, including 6 type 1 and 4 type 2 sequences. These sequences evolves during 37Ma,the estimated average time of a sequences is 3~7Ma,with being generally 1~2Ma,the longest being about 10Ma. type 1 and type 2 sequence boundaries are identified, in Upper Triassic Sinda back\|arc basin two type 1 and one type 2 sequences are divided. Relations have been first concluded among mainly controlled factors of sequence stratigraphies in arc and back\|arc basin systems. First, more sequences product and three\|units of its structures are complete in arc systems of complicated tectonic\|volcanic topographies, for example Jomda arc area of island\|sea framework, because lots of deposits are supplied and accumulations are allowed. Secondly, tectonic control is very clear, type 1 boundaries of SQ1 and SQ7 are clearly unconformity interfaces stressed by tectonism.Thirdly,volcanic rocks is greatly related with sequences, and there are various volcanic rocks in mang sequences,for example Jomda sequence stratigraphies,volcanic rocks of calc alkaline suite occurs in LST which thickness occupying in LST is middle; both tholeiite and calc\|alkaline,alkaline suite (Sinda back\|arc area) in TST, thickness smallest; calc\|alkaline suite in HST, Thickness biggest. It proves that intra\|genetic association between volcanic and relative sea\|level changes, which is gained by the concordance of thick curves of volcanic rock and sea\|level in different systematic traces. When thickness of volcanic rocks growing or progressing, relative sea\|level falls; otherwise, when reducing, it rises. There are larger differences in quantities, structures and types of sequences by comparing sequence stratigraphies of arc, back\|arc with craton area. Those varieties are responses for interactions among tectonic\|volcano, sediment and eustacy. It is pointed out that tectonic and arc volcanic processes are crucial.
基金the National Science Foundation for Distinguished Young Scholars (60725105)the SixthProject of the Key Project of National Nature Science Foundation of China (60496316)+2 种基金the National "863" Project (2007AA012288)the National Nature Science Foundation of China (60572146)the "111" Project (B08038).
文摘The optimal design of training sequences for channel estimation in multiple-input multiple-output (MIMO) systems under spatially correlated fading is considered. The channel is assumed to be a block-fading model with spatial correlation known at both the transmitter and the receiver. To minimize the channel estimation error, optimal training sequences are designed to exploit full information of the spatial correlation under the criterion of minimum mean square error (MMSE). It is investigated that the spatial correlation is helpful to decrease the estimation error and the proposed training sequences have good performance via simulations.
文摘The group correlation properties of binary sequences is studied, and a conclusion is drawn that not only the group correlation function of a binary sequence itself is ideal, but also some of its subsets, which code length N is even, is ideal. Finally a general formula of the group correlation of a binary sequence set is derived.
文摘In this paper we propose a new class of ternary Zero Correlation Zone (ZCZ) sequence sets based on binary ZCZ sequence sets construction. It is shown that the proposed ternary ZCZ sequence sets can reach the upper bound on the ZCZ sequences. The performance of the proposed sequences set in asynchronous Direct Sequence-Code Division Multiple Access (DS-CDMA) system is evaluated. In the simulation we used two types of channels: Additive White Gaussian Noise (AWGN) and frequency non-selective fading with AWGN noise. The proposed ternary ZCZ sequence sets show better results, in term of Bit Error Rate (BER), than Hayashi’s ternary ZCZ sequence sets.
文摘The phase change of lacustrine gravity flow deposition is fast and complex. In its reservoir division and correlation, the isochronous problem is very important. Taking the oil formation I of Es3 in Wuhaozhuang oilfield as an example, through the analysis of stratigraphic drilling and logging data in the study area, according to the genetic types of different levels of base level cycle interfaces and the characteristics of high-resolution sequence stratigraphy, this paper subdivides the lacustrine gravity flow oil layer of lower Es3 in Wuhaozhuang Oilfield, divides it into four short-term base level cycle sequences, and establishes the high-resolution isochronous stratigraphic framework of this interval. It is found that the mid-term, short-term and ultra short-term base level cycles correspond to the oil formation, sand layer group and single layer in the oil layer correlation unit of the oilfield respectively. Based on this, the oil layer correlation unit of the interval is divided, and the sublayer correlation model is established according to the identification characteristics of the short-term base level cycle.
基金National Nature Science Foundation of China under Grant No.51778183the National Science Foundation for Distinguished Young Scholars of China under Grant No.51525802
文摘To consider the infl uence of aftershocks in engineering design, the correlations between main shocks and aftershocks should be examined, and an aftershock simulation method with main shock ground motions needs to be developed. In this study, the data on the sequences of main shock–aftershock ground motions and other related parameters were collected. Using these data, correlations between the magnitude, frequency, duration and energy of the main shock–aftershock ground motions were investigated. The results showed that the magnitude of the aftershock can be larger than that of the main shock. The shapes of the Fourier amplitude spectra of main shocks and aftershocks were similar;however, the predominant frequency and high-frequency components of the aftershock tended to be larger. Considering the magnitude diff erence between the main shock and the aftershock, the correlation of durations was explored. Additionally, a new concept, the duration ratio, was defi ned to describe the concentration of seismic energy release, and main shock energy was strongly positively correlated with the energy attenuated during the main shock–aftershock sequence. Finally, based on these results regarding correlation, an aftershock synthesis using recorded main shock ground motions was constructed with the trigonometric series method for seismic design, and some examples are given to analyze the rationality of this synthetic method.
基金the National Natural Science Foundation of China (No.90604035 and 60572142)the Program for New Century Excellent Talents in University (NCET) (No.NECT-05-0795).
文摘In this paper,a property of Frequency Hopping (FH) sequence set with No Hit Zone (NHZ) is analyzed. Based on matrix transform and mapping methods,respectively,two classes of NHZ FH sequences are presented. These NHZ FH sequences have good Hamming auto-correlation and Hamming cross-correlation properties. FH Code-Division Multiple Access (FH-CDMA) communication systems employing such NHZ FH sequences will eliminate multiple-access interference if the maximum time delay is shorter than the length of the NHZ.
基金This work is supported by the National Key R&D Program of China(2016QY05X1000)the National Natural Science Foundation of China(Grant No.201561402137).
文摘With the continuous development of network technology,various large-scale cyber-attacks continue to emerge.These attacks pose a severe threat to the security of systems,networks,and data.Therefore,how to mine attack patterns from massive data and detect attacks are urgent problems.In this paper,an approach for attack mining and detection is proposed that performs tasks of alarm correlation,false-positive elimination,attack mining,and attack prediction.Based on the idea of CluStream,the proposed approach implements a flow clustering method and a two-step algorithm that guarantees efficient streaming and clustering.The context of an alarm in the attack chain is analyzed and the LightGBM method is used to perform falsepositive recognition with high accuracy.To accelerate the search for the filtered alarm sequence data to mine attack patterns,the PrefixSpan algorithm is also updated in the store strategy.The updated PrefixSpan increases the processing efficiency and achieves a better result than the original one in experiments.With Bayesian theory,the transition probability for the sequence pattern string is calculated and the alarm transition probability table constructed to draw the attack graph.Finally,a long-short-term memory network and embedding word-vector method are used to perform online prediction.Results of numerical experiments show that the method proposed in this paper has a strong practical value for attack detection and prediction.
基金Supported by the National Natural Science Foundation of China (61004139)Beijing Municipal Natural Science Foundation(4101001)2008 Yangtze Fund Scholar and Innovative Research Team Development Schemes of Ministry of Education
文摘Speedometer identification has been researched for many years.The common approaches to that problem are usually based on image subtraction,which does not adapt to image offsets caused by camera vibration.To cope with the rapidity,robust and accurate requirements of this kind of work in dynamic scene,a fast speedometer identification algorithm is proposed,it utilizes phase correlation method based on regional entire template translation to estimate the offset between images.In order to effectively reduce unnecessary computation and false detection rate,an improved linear Hough transform method with two optimization strategies is presented for pointer line detection.Based on VC++ 6.0 software platform with OpenCV library,the algorithm performance under experiments has shown that it celerity and precision.
基金Supported by the National Natural Science Foundation of China (No.60772087, No.90604035)111 Project (No.111- 2-14)
文摘In this paper, a multicarrier DS-CDMA system which employs Z-Complementary Se- quences (ZCS) as spreading code is investigated. The new system can not only eliminate multipath interference and Multiple Access Interference (MAI), but also support flexible number of users com- pared with system using Orthogonal Complementary (OC) codes. Multicarrier DS-CDMA using OC codes can be regarded as a special case of our proposed system. Zero Correlation Zone (ZCZ) of ZCS can be flexibly adjusted to meet the requirements on the user number and maximum multipath and in- ter-user delay, in this way, more users can be supported without losing interference-free property. The effectiveness of the proposed system is validated through theoretical analysis and simulation results.