We first design a discrete hyperchaotic system via piece-wise linear state feedback. The states of the closed loop system are locally expanding in two directions but absolutely bounded on the whole, which implies hype...We first design a discrete hyperchaotic system via piece-wise linear state feedback. The states of the closed loop system are locally expanding in two directions but absolutely bounded on the whole, which implies hyperchaos. Then, we use three suchlike hyperchaotic systems with different feedback gain matrices to design a pseudo-random sequence generator (PRSG). Through a threshold function, three sub-sequences generated from the output of piecewise linear functions are changed into 0-1 sequences. Then, followed by XOR operation, an unpredictable pseudo-random sequence (PRS) is ultimately obtained. The analysis and simulation results indicate that the PRS, generated with hyperchaotic systems, has desirable statistical features.展开更多
This paper proposes new hierarchical structures for generating pseudorandom sequences and arrays. The principle of the structures is based on a new concept-multi-interleaving. It is the generalization of normal sequen...This paper proposes new hierarchical structures for generating pseudorandom sequences and arrays. The principle of the structures is based on a new concept-multi-interleaving. It is the generalization of normal sequence decimation(sampling). The kernal of the structures is a lower speed linear feedback shift register together with several high speed time-division multiplexers arranged hierarchically. These new structures have much higher speed compared with that of other schemes proposed before.展开更多
This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR....This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR. First, without any a priori knowledge of the DS/SS signal, the carrier wave signal can be detected from DS/SS signal with negative SNR by using stochastic differential equations and energy detection method. Based on this, the pseudo-random sequence can also be blindly detected in DS/SS signal with negative SNR by reducing noise of the nonlinear signal and the algorithm of wavelet multiscale decomposition algorithm. Finally, the computer simulation shows that we can detect the carrier wave signal with SNR=-27 dB and the pseudo-random sequence under error code ratio 10^-4with SNR =-10 dB.展开更多
By analysis and comparison of several chaotic systems that are applied to generate pseudo-random sequence, the generalized Henon map is proposed as a pseudo-random sequence generator. A new algorithm is created to sol...By analysis and comparison of several chaotic systems that are applied to generate pseudo-random sequence, the generalized Henon map is proposed as a pseudo-random sequence generator. A new algorithm is created to solve the problem of non-uniform distribution of the sequence generated by the generalized Henon map. First, move the decimal point of elements in the sequence to the fight; then, cut off the integer; and finally, quantify it into a binary sequence. Statistical test, security analysis, and the application of image encryption have strongly supported the good random statistical characteristics, high linear complexity, large key space, and great sensitivity of the binary sequence.展开更多
A pseudo-random sequence generator is a basic tool for cryptography. To realize a pseudo-random sequence generator, a new block iterating method using shifter, multiplier, and adder operations has been introduced. By ...A pseudo-random sequence generator is a basic tool for cryptography. To realize a pseudo-random sequence generator, a new block iterating method using shifter, multiplier, and adder operations has been introduced. By increasing the iteration of the counter and by performing calculations based on the initial value, an approximate pseudo-random sequence was obtained after exchanging bits. The algorithm and the complexity of the generator were introduced. The result obtained from the calculation shows that the self-correlation of the ＂m＂ block sequence is two-valued; the block field value is [0, 2^m - 1 ], and the block period is 2^m＋8 - 1.展开更多
In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice ...In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice of signal type for different exploration tasks.By the threshold of the amplitude of the transmitted signal,a set of candidate frequencies are first selected.Then,by operating a spectrum envelope method at these candidate frequencies on received data,effective components in data are extracted.A frequency density calculation method is proposed based on a logical number summation method,to reasonably characterize the frequency density in different frequency bands.By applying this method to real data in Sichuan,China,with signal Type 13,75 effective components are extracted,including both main frequencies and harmonics.The result suggests that the number of effective frequencies in the 2^(n) sequence pseudo-random signal can be increased by extracting usable harmonics,without any additional fieldwork.展开更多
The Fushan Depression is one of the petroliferous depressions in the Beibuwan Basin,South China Sea.Previous studies have preliminarily explored the origin and source of crude oils in some areas of this depression.Nev...The Fushan Depression is one of the petroliferous depressions in the Beibuwan Basin,South China Sea.Previous studies have preliminarily explored the origin and source of crude oils in some areas of this depression.Nevertheless,no systematic investigations on the classification and origin of oils and hy-drocarbon migration processes have been made for the entire petroleum system in this depression,which has significantly hindered the hydrocarbon exploration in the region.A total of 32 mudstone and 58 oil samples from the Fushan Depression were analyzed to definite the detailed oil-source correlation within the sequence and sedimentary framework.The organic matter of third member of Paleogene Liushagang Formation(Els(3))source rocks,both deltaic and lacustrine mudstone,are algal-dominated with high abundance of C_(23)tricyclic terpane and C_(30)4-methylsteranes.The deltaic source rocks occur-ring in the first member(Els_(1))and second member(Els_(2))of the Paleogene Liushagang Formation are characterized by high abundance of C_(19+20)tricyclic terpane and oleanane,reflecting a more terrestrial plants contribution.While lacustrine source rocks of Els_(1)and Els_(2)display the reduced input of terrige-nous organic matter with relatively low abundance of C 19+20 tricyclic terpane and oleanane.Three types of oils were identified by their biomarker compositions in this study.Most of the oils discovered in the Huachang and Bailian Els_(1)reservoir belong to group A and were derived from lacustrine source rocks of Els_(1)and Els_(2).Group B oils are found within the Els_(1)and Els_(2)reservoirs,showing a close relation to the deltaic source rocks of Els_(1)and Els_(2),respectively.Group C oils,occurring in the Els3 reservoirs,have a good affinity with the Els3 source rocks.The spatial distribution and accumulation of different groups of oils are mainly controlled by the sedimentary facies and specific structural conditions.The Els_(2)reservoir in the Yong'an area belonging to Group B oil,are adjacent to the source kitchen and could be considered as the favorable exploration area in the future.展开更多
To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D sei...To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D seismic and drilling data,and reservoir sections are thoroughly investigated.Guided by the theory of sequence stratigraphy,the progradational sequence stratigraphic framework of the Yanchang Formation is systematically constructed to elucidate new deposition mechanisms in the depressed lacustrine basin,and it has been successfully applied to the exploration and development practices in the Qingcheng Oilfield.Key findings are obtained in three aspects.First,the seismic progradational reflections,marker tuff beds,and condensed sections of flooding surfaces in the Yanchang Formation are consistent and isochronous.Using flooding surface markers as a reference,a progradational sequence stratigraphic architecture is reconstructed for the middle-upper part of Yanchang Formation,and divided into seven clinoform units(CF1-CF7).Second,progradation predominantly occurs in semi-deep to deep lake environments,with the depositional center not always coinciding with the thickest strata.The lacustrine basin underwent an evolution of“oscillatory regression-progradational infilling-multi-phase superimposition”.Third,the case study of Qingcheng Oilfield reveals that the major pay zones consist of“isochronous but heterochronous”gravity-flow sandstone complexes.Guided by the progradational sequence stratigraphic architecture,horizontal well oil-layer penetration rates remain above 82%.The progradational sequence stratigraphic architecture and associated geological insights are more consistent with the sedimentary infilling mechanisms of large-scale continental depressed lacustrine basins and actual drilling results.The research results provide crucial theoretical and technical support for subsequent refined exploration and development of the Yanchang Formation,and are expected to offer a reference for research and production practice in similar continental lacustrine basins.展开更多
Attempts have been made to modulate motor sequence learning(MSL)through repetitive transcranial magnetic stimulation,targeting different sites within the sensorimotor network.However,the target with the optimum modula...Attempts have been made to modulate motor sequence learning(MSL)through repetitive transcranial magnetic stimulation,targeting different sites within the sensorimotor network.However,the target with the optimum modulatory effect on neural plasticity associated with MSL remains unclarified.This study was therefore designed to compare the role of the left primary motor cortex and the left supplementary motor area proper(SMAp)in modulating MSL across different complexity levels and for both hands,as well as the associated neuroplasticity by applying intermittent theta burst stimulation together with the electroencephalogram and concurrent transcranial magnetic stimulation.Our data demonstrated the role of SMAp stimulation in modulating neural communication to support MSL,which is achieved by facilitating regional activation and orchestrating neural coupling across distributed brain regions,particularly in interhemispheric connections.These findings may have important clinical implications,particularly for motor rehabilitation in populations such as post-stroke patients.展开更多
Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the ...Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.展开更多
This paper presents modified version of a realistic test tool suitable to Design For Testability （DFT） and Built-ln Self Test （BIST） environments. A comprehensive tool is developed in the form of a test simulator....This paper presents modified version of a realistic test tool suitable to Design For Testability （DFT） and Built-ln Self Test （BIST） environments. A comprehensive tool is developed in the form of a test simulator. The simulator is capable of providing a required goal of test for the Circuit Under Test （CUT）. The simulator uses the approach of fault diagnostics with fault grading procedures to provide the optimum tests. The current version of the simulator embeds features of exhaustive and pseudo-random test generation schemes along with the search solutions of cost effective test goals. The simulator provides facilities of realizing all possible pseudo-random sequence generators with all possible combinations of seeds. The tool is developed on a common Personal Computer （PC） platform and hence no special software is required. Thereby, it is a low cost tool hence economical. The tool is very much suitable for determining realistic test sequences for a targeted goal of testing for any CUT. The developed tool incorporates flexible Graphical User Interface （GUI） procedures and can be operated without any special programming skill. The tool is debugged and tested with the results of many bench mark circuits. Further, this developed tool can be utilized for educational purposes for many courses such as fault-tolerant computing, fault diagnosis, digital electronics, and safe-reliable-testable digital logic designs.展开更多
Cystic echinococcosis (CE) is a prevalent zoonotic disease caused by Echinococcus granulosus, with a cosmopolitan distribution. The parasite is transmitted cyclically between canines and numerous intermediate herbivor...Cystic echinococcosis (CE) is a prevalent zoonotic disease caused by Echinococcus granulosus, with a cosmopolitan distribution. The parasite is transmitted cyclically between canines and numerous intermediate herbivorous livestock animals. Also, other Taeniid tapeworms could infect domestic dogs and they pose significant veterinary and public health concerns worldwide. This study aimed to develop a sensitive molecular method for detecting Echinococcus spp. DNA in dog fecal samples using next-generation sequencing (NGS). A set of PCR primers targeting conserved regions of Taeniid tapeworms’ 18s rRNA genes was designed and tested for amplifying genomic DNA from various tapeworm species. The PCR system demonstrated high sensitivity, amplifying DNA from all tested tapeworm species, with differences observed in amplified band sizes. The primers were adapted for NGS analysis by adding forward and reverse adapters, enabling the sequencing of amplified DNA fragments. Application of the developed PCR system to dog fecal samples collected from Yatta town, Palestine, revealed the presence of E. granulosus DNA in five out of 50 samples. NGS analysis confirmed the specificity of the amplified DNA fragments, showing 98% - 99% similarity with the 18s rDNA gene of E. granulosus. This study demonstrates the utility of NGS-based molecular methods for accurate and sensitive detection of Echinococcus spp. in dog fecal samples, providing valuable insights for epidemiological surveillance and control programs of echinococcosis in endemic regions.展开更多
Binary sequences constructed by Legendre symbols are widely used in communication and cryptography since they have many good pseudo-random properties.In this paper,we determine the 2-adic complexity of the sum sequenc...Binary sequences constructed by Legendre symbols are widely used in communication and cryptography since they have many good pseudo-random properties.In this paper,we determine the 2-adic complexity of the sum sequence of any k many Legendre sequences and show that the 2-adic complexity of the sum sequences of any k many Legendre sequences reaches the maximum by proving the case of k=2 and 3,which implies that the sum sequences can resist the attack of rational approximation algorithm.展开更多
<正> The performance of individual pseudo-random sequence, generated by some mechanism, is often not ideal. The asymptotic performance of the addition (in the sense (mod p) of a large number of such individual s...<正> The performance of individual pseudo-random sequence, generated by some mechanism, is often not ideal. The asymptotic performance of the addition (in the sense (mod p) of a large number of such individual sequences is studied and the necessary and sufficient condition under which the resulting sequence may converge to genuine randomness is obtained.展开更多
In industrial control systems,such as power transmission facilities and water treatment plants,Programmable Logic Controllers(PLCs)can work consistently and stably over long periods if there are no faults.Black-box id...In industrial control systems,such as power transmission facilities and water treatment plants,Programmable Logic Controllers(PLCs)can work consistently and stably over long periods if there are no faults.Black-box identification aims to automatically construct Petri net models with the help of I/O signals from PLC devices only.The main challenge is how to convert the infinitely long PLC signals into an event sequence,which is the foundation for subsequent modeling.The current algorithms are confronted with a number of challenges,including an exponential increase in the number of transitions,high time complexity,and susceptibility to noisy signals.To solve these problems,this paper proposes a new method for converting PLC signals into a transition sequence.The method is based on the principles of Boolean absorption law,which filters out noise information in the I/O signals.Then firing functions representing input–output causality are constructed from the filtered signals.Finally,the original signal sequence is traversed to generate a transition sequence.The experimental results show that these methods can rapidly identify a transition sequence.Compared to traditional methods,the proposed algorithms have polynomial time complexity.展开更多
Performing the high-resolution stratigraphic analysis may be challenging and time-consuming if one has to work with large datasets.Moreover,sedimentary records have signals of different frequencies and intrinsic noise...Performing the high-resolution stratigraphic analysis may be challenging and time-consuming if one has to work with large datasets.Moreover,sedimentary records have signals of different frequencies and intrinsic noise,resulting in a complex signature that is difficult to identify only through eyes-based analysis.This work proposes identifying transgressive-regressive(T-R)sequences from carbonate facies successions of three South American basins:(i)São Francisco Basin-Brazil,(ii)Santos Basin-Brazil,and(iii)Salta Basin-Argentina.We applied a hidden Markov model in an unsupervised approach followed by a Score-Based Recommender System that automatically finds medium or low-frequency sedimentary cycles from high-frequency ones.Our method is applied to facies identified using Fullbore Formation Microimager(FMI)logs,outcrop description,and composite logs from carbonate intervals.The automatic recommendation results showed better long-distance correlations between medium-to low-frequency sedimentary cycles,whereas the hidden Markov model method successfully identified high-resolution(high-frequency)transgressive and regressive systems tracts from the given facies successions.Our workflow offers advances in the automated analyses and construction of to lower-higher-rank stratigraphic framework and short to long-distance stratigraphic correlation,allowing for scale large-automated processing of the basin dataset.Our approach in this work fits the unsupervised learning framework,as we require no previous input of stratigraphical analysis in the basin.The results provide solutions for prospecting any sediment-hosted mineral resource,especially for the oil and gas industry,offering support for subsurface geological characterization,whether at the exploration scale or for reservoir zoning during production development.展开更多
The optimization of polymer structures aims to determine an optimal sequence or topology that achieves a given target property or structural performance.This inverse design problem involves searching within a vast com...The optimization of polymer structures aims to determine an optimal sequence or topology that achieves a given target property or structural performance.This inverse design problem involves searching within a vast combinatorial phase space defined by components,se-quences,and topologies,and is often computationally intractable due to its NP-hard nature.At the core of this challenge lies the need to evalu-ate complex correlations among structural variables,a classical problem in both statistical physics and combinatorial optimization.To address this,we adopt a mean-field approach that decouples direct variable-variable interactions into effective interactions between each variable and an auxiliary field.The simulated bifurcation(SB)algorithm is employed as a mean-field-based optimization framework.It constructs a Hamiltonian dynamical system by introducing generalized momentum fields,enabling efficient decoupling and dynamic evolution of strongly coupled struc-tural variables.Using the sequence optimization of a linear copolymer adsorbing on a solid surface as a case study,we demonstrate the applica-bility of the SB algorithm to high-dimensional,non-differentiable combinatorial optimization problems.Our results show that SB can efficiently discover polymer sequences with excellent adsorption performance within a reasonable computational time.Furthermore,it exhibits robust con-vergence and high parallel scalability across large design spaces.The approach developed in this work offers a new computational pathway for polymer structure optimization.It also lays a theoretical foundation for future extensions to topological design problems,such as optimizing the number and placement of side chains,as well as the co-optimization of sequence and topology.展开更多
Disaster mitigation necessitates scientifi c and accurate aftershock forecasting during the critical 2 h after an earthquake. However, this action faces immense challenges due to the lack of early postearthquake data ...Disaster mitigation necessitates scientifi c and accurate aftershock forecasting during the critical 2 h after an earthquake. However, this action faces immense challenges due to the lack of early postearthquake data and the unreliability of forecasts. To obtain foundational data for sequence parameters of the land-sea adjacent zone and establish a reliable and operational aftershock forecasting framework, we combined the initial sequence parameters extracted from envelope functions and incorporated small-earthquake information into our model to construct a Bayesian algorithm for the early postearthquake stage. We performed parameter fitting and early postearthquake aftershock occurrence rate forecasting and effectiveness evaluation for 36 earthquake sequences with M ≥ 4.0 in the Bohai Rim region since 2010. According to the results, during the early stage after the mainshock, earthquake sequence parameters exhibited relatively drastic fl uctuations with signifi cant errors. The integration of prior information can mitigate the intensity of these changes and reduce errors. The initial and stable sequence parameters generally display advantageous distribution characteristics, with each parameter’s distribution being relatively concentrated and showing good symmetry and remarkable consistency. The sequence parameter p-values were relatively small, which indicates the comparatively slow attenuation of signifi cant earthquake events in the Bohai Rim region. A certain positive correlation was observed between earthquake sequence parameters b and p. However, sequence parameters are unrelated to the mainshock magnitude, which implies that their statistical characteristics and trends are universal. The Bayesian algorithm revealed a good forecasting capability for aftershocks in the early postearthquake period (2 h) in the Bohai Rim region, with an overall forecasting effi cacy rate of 76.39%. The proportion of “too low” failures exceeded that of “too high” failures, and the number of forecasting failures for the next three days was greater than that for the next day.展开更多
The study of sequence stratigraphy often focuses on shallow marine and shelf-edge regions,while research on deep-sea stratigraphic sequences remains relatively weak.This study,based on highresolution 3D seismic data a...The study of sequence stratigraphy often focuses on shallow marine and shelf-edge regions,while research on deep-sea stratigraphic sequences remains relatively weak.This study,based on highresolution 3D seismic data and drilling information,utilized sequence stratigraphy and seismic sedimentology as guidelines,and employed seismic interpretation methods to performed a division of deepsea stratigraphic sequences within the Romney 3D seismic survey area in the deep-water Taranaki Basin,New Zealand.Furthermore,it analyzed the characteristics of typical depositional systems and their associated controlling factors.The findings are as follows:(1)Based on seismic reflection termination relationships and seismic facies characteristics,four second-order sequence boundaries and nine thirdorder sequence boundaries were identified,resulting in the delineation of three second-order sequences and twelve third-order sequences in the basin.(2)Five seismic facies were recognized,corresponding to five typical sedimentary bodies:mass transport deposits(MTDs),deep-water channel,levee deposits,deltaic deposits,and pelagic deposits.However,due to the relatively thin sedimentary thickness of carbonate sediments,the seismic facies characteristics of carbonate sediments cannot be discerned in seismic data,but can be identified based on well data.Deltaic sediments mainly developed during the rift stage of the basin,while carbonate sediments formed during the transition from a passive to an active margin.Deep-water channel and levee deposits and MTDs emerged during the active margin stage,while pelagic deposits are ubiquitous in marine environments.(3)The uplift of New Zealand's interior and climate-driven erosion caused the resurgence of clastic sediments,which began to be transported to the deep sea,the seafloor topography would directly affect the movement path of sediment gravity flow,and sediment supply can affect the development and evolution of sedimentary systems.(4)Event deposits boundaries,such as erosional scour surfaces formed by channels and unconformities created by MTDs,can serve as boundaries for the division of deep-water stratigraphic sequences.This study proposes a method for delineating deep-water stratigraphic sequences using event deposits,particularly suitable under conditions where the influence of relative sea-level changes on deep-water deposits is relatively weak.This research not only enhances the understanding of deep-water depositional sequences but also provides a reference for studies on the evolution of deep-water deposition and its controlling factors in research areas with similar geological backgrounds worldwide.展开更多
Fibonacci sequence,generated by summing the preceding two terms,is a classical sequence renowned for its elegant properties.In this paper,leveraging properties of generalized Fibonacci sequences and formulas for conse...Fibonacci sequence,generated by summing the preceding two terms,is a classical sequence renowned for its elegant properties.In this paper,leveraging properties of generalized Fibonacci sequences and formulas for consecutive sums of equidistant sub-sequences,we investigate the ratio of the sum of numbers along main-diagonal and sub-diagonal of odd-order grids containing generalized Fibonacci sequences.We show that this ratio is solely dependent on the order of the grid,providing a concise and splendid identity.展开更多
基金This project was supported by the National Natural Science Foundation of China (69874025).
文摘We first design a discrete hyperchaotic system via piece-wise linear state feedback. The states of the closed loop system are locally expanding in two directions but absolutely bounded on the whole, which implies hyperchaos. Then, we use three suchlike hyperchaotic systems with different feedback gain matrices to design a pseudo-random sequence generator (PRSG). Through a threshold function, three sub-sequences generated from the output of piecewise linear functions are changed into 0-1 sequences. Then, followed by XOR operation, an unpredictable pseudo-random sequence (PRS) is ultimately obtained. The analysis and simulation results indicate that the PRS, generated with hyperchaotic systems, has desirable statistical features.
文摘This paper proposes new hierarchical structures for generating pseudorandom sequences and arrays. The principle of the structures is based on a new concept-multi-interleaving. It is the generalization of normal sequence decimation(sampling). The kernal of the structures is a lower speed linear feedback shift register together with several high speed time-division multiplexers arranged hierarchically. These new structures have much higher speed compared with that of other schemes proposed before.
基金the National Defence Key Foundation of China (Grant No. 614144)
文摘This paper introduces a new theory and algorithm that can be used in blind detection of the carrier wave signal and the pseudo-random sequence of the direct sequence spread spectrum （DS/SS） signal with negative SNR. First, without any a priori knowledge of the DS/SS signal, the carrier wave signal can be detected from DS/SS signal with negative SNR by using stochastic differential equations and energy detection method. Based on this, the pseudo-random sequence can also be blindly detected in DS/SS signal with negative SNR by reducing noise of the nonlinear signal and the algorithm of wavelet multiscale decomposition algorithm. Finally, the computer simulation shows that we can detect the carrier wave signal with SNR=-27 dB and the pseudo-random sequence under error code ratio 10^-4with SNR =-10 dB.
基金the National Natural Science Foundation of China (60372061)
文摘By analysis and comparison of several chaotic systems that are applied to generate pseudo-random sequence, the generalized Henon map is proposed as a pseudo-random sequence generator. A new algorithm is created to solve the problem of non-uniform distribution of the sequence generated by the generalized Henon map. First, move the decimal point of elements in the sequence to the fight; then, cut off the integer; and finally, quantify it into a binary sequence. Statistical test, security analysis, and the application of image encryption have strongly supported the good random statistical characteristics, high linear complexity, large key space, and great sensitivity of the binary sequence.
文摘A pseudo-random sequence generator is a basic tool for cryptography. To realize a pseudo-random sequence generator, a new block iterating method using shifter, multiplier, and adder operations has been introduced. By increasing the iteration of the counter and by performing calculations based on the initial value, an approximate pseudo-random sequence was obtained after exchanging bits. The algorithm and the complexity of the generator were introduced. The result obtained from the calculation shows that the self-correlation of the ＂m＂ block sequence is two-valued; the block field value is [0, 2^m - 1 ], and the block period is 2^m＋8 - 1.
基金financially supported by the National Key Research and Development Program of China(No.2019YFC0604902)the National Natural Science Foundation of China(No.42004056)the Natural Science Foundation of Shandong Province,China(No.ZR201911010111).
文摘In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice of signal type for different exploration tasks.By the threshold of the amplitude of the transmitted signal,a set of candidate frequencies are first selected.Then,by operating a spectrum envelope method at these candidate frequencies on received data,effective components in data are extracted.A frequency density calculation method is proposed based on a logical number summation method,to reasonably characterize the frequency density in different frequency bands.By applying this method to real data in Sichuan,China,with signal Type 13,75 effective components are extracted,including both main frequencies and harmonics.The result suggests that the number of effective frequencies in the 2^(n) sequence pseudo-random signal can be increased by extracting usable harmonics,without any additional fieldwork.
基金funded by the South Oil Exploration and Development Company of PetroChina(2021-HNYJ-010).
文摘The Fushan Depression is one of the petroliferous depressions in the Beibuwan Basin,South China Sea.Previous studies have preliminarily explored the origin and source of crude oils in some areas of this depression.Nevertheless,no systematic investigations on the classification and origin of oils and hy-drocarbon migration processes have been made for the entire petroleum system in this depression,which has significantly hindered the hydrocarbon exploration in the region.A total of 32 mudstone and 58 oil samples from the Fushan Depression were analyzed to definite the detailed oil-source correlation within the sequence and sedimentary framework.The organic matter of third member of Paleogene Liushagang Formation(Els(3))source rocks,both deltaic and lacustrine mudstone,are algal-dominated with high abundance of C_(23)tricyclic terpane and C_(30)4-methylsteranes.The deltaic source rocks occur-ring in the first member(Els_(1))and second member(Els_(2))of the Paleogene Liushagang Formation are characterized by high abundance of C_(19+20)tricyclic terpane and oleanane,reflecting a more terrestrial plants contribution.While lacustrine source rocks of Els_(1)and Els_(2)display the reduced input of terrige-nous organic matter with relatively low abundance of C 19+20 tricyclic terpane and oleanane.Three types of oils were identified by their biomarker compositions in this study.Most of the oils discovered in the Huachang and Bailian Els_(1)reservoir belong to group A and were derived from lacustrine source rocks of Els_(1)and Els_(2).Group B oils are found within the Els_(1)and Els_(2)reservoirs,showing a close relation to the deltaic source rocks of Els_(1)and Els_(2),respectively.Group C oils,occurring in the Els3 reservoirs,have a good affinity with the Els3 source rocks.The spatial distribution and accumulation of different groups of oils are mainly controlled by the sedimentary facies and specific structural conditions.The Els_(2)reservoir in the Yong'an area belonging to Group B oil,are adjacent to the source kitchen and could be considered as the favorable exploration area in the future.
基金Supported by the National Science and Technology Major Project(2017ZX05001)CNPC Technology Project(2023YQX20111).
文摘To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D seismic and drilling data,and reservoir sections are thoroughly investigated.Guided by the theory of sequence stratigraphy,the progradational sequence stratigraphic framework of the Yanchang Formation is systematically constructed to elucidate new deposition mechanisms in the depressed lacustrine basin,and it has been successfully applied to the exploration and development practices in the Qingcheng Oilfield.Key findings are obtained in three aspects.First,the seismic progradational reflections,marker tuff beds,and condensed sections of flooding surfaces in the Yanchang Formation are consistent and isochronous.Using flooding surface markers as a reference,a progradational sequence stratigraphic architecture is reconstructed for the middle-upper part of Yanchang Formation,and divided into seven clinoform units(CF1-CF7).Second,progradation predominantly occurs in semi-deep to deep lake environments,with the depositional center not always coinciding with the thickest strata.The lacustrine basin underwent an evolution of“oscillatory regression-progradational infilling-multi-phase superimposition”.Third,the case study of Qingcheng Oilfield reveals that the major pay zones consist of“isochronous but heterochronous”gravity-flow sandstone complexes.Guided by the progradational sequence stratigraphic architecture,horizontal well oil-layer penetration rates remain above 82%.The progradational sequence stratigraphic architecture and associated geological insights are more consistent with the sedimentary infilling mechanisms of large-scale continental depressed lacustrine basins and actual drilling results.The research results provide crucial theoretical and technical support for subsequent refined exploration and development of the Yanchang Formation,and are expected to offer a reference for research and production practice in similar continental lacustrine basins.
基金supported by grants from the Zhejiang Provincial Natural Science Foundation(LGJ22H180001)Zhejiang Medical and Health Science and Technology Project(2021KY249)the National Key R&D Program of China(2017YFC1310000).
文摘Attempts have been made to modulate motor sequence learning(MSL)through repetitive transcranial magnetic stimulation,targeting different sites within the sensorimotor network.However,the target with the optimum modulatory effect on neural plasticity associated with MSL remains unclarified.This study was therefore designed to compare the role of the left primary motor cortex and the left supplementary motor area proper(SMAp)in modulating MSL across different complexity levels and for both hands,as well as the associated neuroplasticity by applying intermittent theta burst stimulation together with the electroencephalogram and concurrent transcranial magnetic stimulation.Our data demonstrated the role of SMAp stimulation in modulating neural communication to support MSL,which is achieved by facilitating regional activation and orchestrating neural coupling across distributed brain regions,particularly in interhemispheric connections.These findings may have important clinical implications,particularly for motor rehabilitation in populations such as post-stroke patients.
基金Supported by Leading Talent Program of Autonomous Region(2022TSYCLJ0070)PetroChina Prospective and Basic Technological Project(2021DJ0108)Natural Science Foundation for Outstanding Young People in Shandong Province(ZR2022YQ30).
文摘Based on the experimental results of casting thin section,low temperature nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance T2 spectrum,contact angle and oil-water interfacial tension,the relationship between pore throat structure and crude oil mobility characteristics of full particle sequence reservoirs in the Lower Permian Fengcheng Formation of Mahu Sag,Junggar Basin,are revealed.(1)With the decrease of reservoir particle size,the volume of pores connected by large throats and the volume of large pores show a decreasing trend,and the distribution and peak ranges of throat and pore radius shift to smaller size in an orderly manner.The upper limits of throat radius,porosity and permeability of unconventional reservoirs in Fengcheng Formation are approximately 0.7μm,8%and 0.1×10^(−3)μm^(2),respectively.(2)As the reservoir particle size decreases,the distribution and peak ranges of pores hosting retained oil and movable oil are shifted to a smaller size in an orderly manner.With the increase of driving pressure,the amount of retained and movable oil of the larger particle reservoir samples shows a more obvious trend of decreasing and increasing,respectively.(3)With the increase of throat radius,the driving pressure of reservoir with different particle levels presents three stages,namely rapid decrease,slow decrease and stabilization.The oil driving pressures of various reservoirs and the differences of them decrease with the increase of temperature and obviously decrease with the increase of throat radius.According to the above experimental analysis,it is concluded that the deep shale oil of Fengcheng Formation in Mahu Sag has great potential for production under geological conditions.
文摘This paper presents modified version of a realistic test tool suitable to Design For Testability （DFT） and Built-ln Self Test （BIST） environments. A comprehensive tool is developed in the form of a test simulator. The simulator is capable of providing a required goal of test for the Circuit Under Test （CUT）. The simulator uses the approach of fault diagnostics with fault grading procedures to provide the optimum tests. The current version of the simulator embeds features of exhaustive and pseudo-random test generation schemes along with the search solutions of cost effective test goals. The simulator provides facilities of realizing all possible pseudo-random sequence generators with all possible combinations of seeds. The tool is developed on a common Personal Computer （PC） platform and hence no special software is required. Thereby, it is a low cost tool hence economical. The tool is very much suitable for determining realistic test sequences for a targeted goal of testing for any CUT. The developed tool incorporates flexible Graphical User Interface （GUI） procedures and can be operated without any special programming skill. The tool is debugged and tested with the results of many bench mark circuits. Further, this developed tool can be utilized for educational purposes for many courses such as fault-tolerant computing, fault diagnosis, digital electronics, and safe-reliable-testable digital logic designs.
文摘Cystic echinococcosis (CE) is a prevalent zoonotic disease caused by Echinococcus granulosus, with a cosmopolitan distribution. The parasite is transmitted cyclically between canines and numerous intermediate herbivorous livestock animals. Also, other Taeniid tapeworms could infect domestic dogs and they pose significant veterinary and public health concerns worldwide. This study aimed to develop a sensitive molecular method for detecting Echinococcus spp. DNA in dog fecal samples using next-generation sequencing (NGS). A set of PCR primers targeting conserved regions of Taeniid tapeworms’ 18s rRNA genes was designed and tested for amplifying genomic DNA from various tapeworm species. The PCR system demonstrated high sensitivity, amplifying DNA from all tested tapeworm species, with differences observed in amplified band sizes. The primers were adapted for NGS analysis by adding forward and reverse adapters, enabling the sequencing of amplified DNA fragments. Application of the developed PCR system to dog fecal samples collected from Yatta town, Palestine, revealed the presence of E. granulosus DNA in five out of 50 samples. NGS analysis confirmed the specificity of the amplified DNA fragments, showing 98% - 99% similarity with the 18s rDNA gene of E. granulosus. This study demonstrates the utility of NGS-based molecular methods for accurate and sensitive detection of Echinococcus spp. in dog fecal samples, providing valuable insights for epidemiological surveillance and control programs of echinococcosis in endemic regions.
文摘Binary sequences constructed by Legendre symbols are widely used in communication and cryptography since they have many good pseudo-random properties.In this paper,we determine the 2-adic complexity of the sum sequence of any k many Legendre sequences and show that the 2-adic complexity of the sum sequences of any k many Legendre sequences reaches the maximum by proving the case of k=2 and 3,which implies that the sum sequences can resist the attack of rational approximation algorithm.
基金Project supported by the National Natural Science Foundation of China,the UPGC of Hong Kong,Hong Kong Baptist University and SRCU.
文摘<正> The performance of individual pseudo-random sequence, generated by some mechanism, is often not ideal. The asymptotic performance of the addition (in the sense (mod p) of a large number of such individual sequences is studied and the necessary and sufficient condition under which the resulting sequence may converge to genuine randomness is obtained.
基金supported by the Science and Technology Planning Project of Fujian Province,China,under Grant No.2024H0014(2024H01010100).
文摘In industrial control systems,such as power transmission facilities and water treatment plants,Programmable Logic Controllers(PLCs)can work consistently and stably over long periods if there are no faults.Black-box identification aims to automatically construct Petri net models with the help of I/O signals from PLC devices only.The main challenge is how to convert the infinitely long PLC signals into an event sequence,which is the foundation for subsequent modeling.The current algorithms are confronted with a number of challenges,including an exponential increase in the number of transitions,high time complexity,and susceptibility to noisy signals.To solve these problems,this paper proposes a new method for converting PLC signals into a transition sequence.The method is based on the principles of Boolean absorption law,which filters out noise information in the I/O signals.Then firing functions representing input–output causality are constructed from the filtered signals.Finally,the original signal sequence is traversed to generate a transition sequence.The experimental results show that these methods can rapidly identify a transition sequence.Compared to traditional methods,the proposed algorithms have polynomial time complexity.
文摘Performing the high-resolution stratigraphic analysis may be challenging and time-consuming if one has to work with large datasets.Moreover,sedimentary records have signals of different frequencies and intrinsic noise,resulting in a complex signature that is difficult to identify only through eyes-based analysis.This work proposes identifying transgressive-regressive(T-R)sequences from carbonate facies successions of three South American basins:(i)São Francisco Basin-Brazil,(ii)Santos Basin-Brazil,and(iii)Salta Basin-Argentina.We applied a hidden Markov model in an unsupervised approach followed by a Score-Based Recommender System that automatically finds medium or low-frequency sedimentary cycles from high-frequency ones.Our method is applied to facies identified using Fullbore Formation Microimager(FMI)logs,outcrop description,and composite logs from carbonate intervals.The automatic recommendation results showed better long-distance correlations between medium-to low-frequency sedimentary cycles,whereas the hidden Markov model method successfully identified high-resolution(high-frequency)transgressive and regressive systems tracts from the given facies successions.Our workflow offers advances in the automated analyses and construction of to lower-higher-rank stratigraphic framework and short to long-distance stratigraphic correlation,allowing for scale large-automated processing of the basin dataset.Our approach in this work fits the unsupervised learning framework,as we require no previous input of stratigraphical analysis in the basin.The results provide solutions for prospecting any sediment-hosted mineral resource,especially for the oil and gas industry,offering support for subsurface geological characterization,whether at the exploration scale or for reservoir zoning during production development.
基金supported by the Fundamental Research Funds for the Central Universities(No.2024JBZX029)Shijiazhuang High Level Science and Technology Innovation and Entrepreneurship Talent Project(No.08202307)the National Natural Science Foundation of China(NSFC)(No.22173004).
文摘The optimization of polymer structures aims to determine an optimal sequence or topology that achieves a given target property or structural performance.This inverse design problem involves searching within a vast combinatorial phase space defined by components,se-quences,and topologies,and is often computationally intractable due to its NP-hard nature.At the core of this challenge lies the need to evalu-ate complex correlations among structural variables,a classical problem in both statistical physics and combinatorial optimization.To address this,we adopt a mean-field approach that decouples direct variable-variable interactions into effective interactions between each variable and an auxiliary field.The simulated bifurcation(SB)algorithm is employed as a mean-field-based optimization framework.It constructs a Hamiltonian dynamical system by introducing generalized momentum fields,enabling efficient decoupling and dynamic evolution of strongly coupled struc-tural variables.Using the sequence optimization of a linear copolymer adsorbing on a solid surface as a case study,we demonstrate the applica-bility of the SB algorithm to high-dimensional,non-differentiable combinatorial optimization problems.Our results show that SB can efficiently discover polymer sequences with excellent adsorption performance within a reasonable computational time.Furthermore,it exhibits robust con-vergence and high parallel scalability across large design spaces.The approach developed in this work offers a new computational pathway for polymer structure optimization.It also lays a theoretical foundation for future extensions to topological design problems,such as optimizing the number and placement of side chains,as well as the co-optimization of sequence and topology.
基金supported by the Natural Science Foundation of Tianjin (No. 22JCQNJC01070)the National Natural Science Foundation of China (No. 42404079)the Key Project of Tianjin Earthquake Agency (No. Zd202402)。
文摘Disaster mitigation necessitates scientifi c and accurate aftershock forecasting during the critical 2 h after an earthquake. However, this action faces immense challenges due to the lack of early postearthquake data and the unreliability of forecasts. To obtain foundational data for sequence parameters of the land-sea adjacent zone and establish a reliable and operational aftershock forecasting framework, we combined the initial sequence parameters extracted from envelope functions and incorporated small-earthquake information into our model to construct a Bayesian algorithm for the early postearthquake stage. We performed parameter fitting and early postearthquake aftershock occurrence rate forecasting and effectiveness evaluation for 36 earthquake sequences with M ≥ 4.0 in the Bohai Rim region since 2010. According to the results, during the early stage after the mainshock, earthquake sequence parameters exhibited relatively drastic fl uctuations with signifi cant errors. The integration of prior information can mitigate the intensity of these changes and reduce errors. The initial and stable sequence parameters generally display advantageous distribution characteristics, with each parameter’s distribution being relatively concentrated and showing good symmetry and remarkable consistency. The sequence parameter p-values were relatively small, which indicates the comparatively slow attenuation of signifi cant earthquake events in the Bohai Rim region. A certain positive correlation was observed between earthquake sequence parameters b and p. However, sequence parameters are unrelated to the mainshock magnitude, which implies that their statistical characteristics and trends are universal. The Bayesian algorithm revealed a good forecasting capability for aftershocks in the early postearthquake period (2 h) in the Bohai Rim region, with an overall forecasting effi cacy rate of 76.39%. The proportion of “too low” failures exceeded that of “too high” failures, and the number of forecasting failures for the next three days was greater than that for the next day.
基金the National Natural Science Foundation of China(Grant Nos.42077410 and 41872112).We acknowledge the insights and efforts of journal editor(Jie Hao)and three anonymous reviewers that improved the quality of the manuscript.
文摘The study of sequence stratigraphy often focuses on shallow marine and shelf-edge regions,while research on deep-sea stratigraphic sequences remains relatively weak.This study,based on highresolution 3D seismic data and drilling information,utilized sequence stratigraphy and seismic sedimentology as guidelines,and employed seismic interpretation methods to performed a division of deepsea stratigraphic sequences within the Romney 3D seismic survey area in the deep-water Taranaki Basin,New Zealand.Furthermore,it analyzed the characteristics of typical depositional systems and their associated controlling factors.The findings are as follows:(1)Based on seismic reflection termination relationships and seismic facies characteristics,four second-order sequence boundaries and nine thirdorder sequence boundaries were identified,resulting in the delineation of three second-order sequences and twelve third-order sequences in the basin.(2)Five seismic facies were recognized,corresponding to five typical sedimentary bodies:mass transport deposits(MTDs),deep-water channel,levee deposits,deltaic deposits,and pelagic deposits.However,due to the relatively thin sedimentary thickness of carbonate sediments,the seismic facies characteristics of carbonate sediments cannot be discerned in seismic data,but can be identified based on well data.Deltaic sediments mainly developed during the rift stage of the basin,while carbonate sediments formed during the transition from a passive to an active margin.Deep-water channel and levee deposits and MTDs emerged during the active margin stage,while pelagic deposits are ubiquitous in marine environments.(3)The uplift of New Zealand's interior and climate-driven erosion caused the resurgence of clastic sediments,which began to be transported to the deep sea,the seafloor topography would directly affect the movement path of sediment gravity flow,and sediment supply can affect the development and evolution of sedimentary systems.(4)Event deposits boundaries,such as erosional scour surfaces formed by channels and unconformities created by MTDs,can serve as boundaries for the division of deep-water stratigraphic sequences.This study proposes a method for delineating deep-water stratigraphic sequences using event deposits,particularly suitable under conditions where the influence of relative sea-level changes on deep-water deposits is relatively weak.This research not only enhances the understanding of deep-water depositional sequences but also provides a reference for studies on the evolution of deep-water deposition and its controlling factors in research areas with similar geological backgrounds worldwide.
基金Supported by the National Natural Science Foundation of China(Grant No.12471298)the Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.23JSQ031)the Shaanxi Province College Student Innovation and Entrepreneurship Training Program(Grant Nos.S202210699481 and S202310699324X).
文摘Fibonacci sequence,generated by summing the preceding two terms,is a classical sequence renowned for its elegant properties.In this paper,leveraging properties of generalized Fibonacci sequences and formulas for consecutive sums of equidistant sub-sequences,we investigate the ratio of the sum of numbers along main-diagonal and sub-diagonal of odd-order grids containing generalized Fibonacci sequences.We show that this ratio is solely dependent on the order of the grid,providing a concise and splendid identity.
