期刊文献+
共找到2,144篇文章
< 1 2 108 >
每页显示 20 50 100
Soliton Solutions of a Coupled KdV System via Backlund Transformation
1
作者 CAO Xifang WU Yiheng +2 位作者 LU Yi XU Wenjing XIA Yutong 《应用数学》 北大核心 2025年第1期211-216,共6页
In this paper we use Böcklund transformation to construct soliton solutions for a coupled KdV system.This system was first proposed by Wang in 2010.First we generalize the well-known Bäcklund transformation ... In this paper we use Böcklund transformation to construct soliton solutions for a coupled KdV system.This system was first proposed by Wang in 2010.First we generalize the well-known Bäcklund transformation for the KdV equation to such coupled KdV system.Then from a trivial seed solution,we construct soliton solutions.We also give a nonlinear superposition formula,which allows us to generate multi-soliton solutions. 展开更多
关键词 KdV equation Coupled KdV system B¨acklund transformation SOLITON
在线阅读 下载PDF
Green and efficient mineral phase transformation of saprolitic nickel laterite ore through fluidized pre-heating and hydrogen-based pre-reduction processes
2
作者 FAN Qing-long YUAN Shuai +2 位作者 LI Yan-jun HE Jia-hao WU Zi-jian 《Journal of Central South University》 2025年第9期3610-3628,共19页
Nickel laterite ore is an important nickel-bearing mineral.Research on pre-heating and hydrogen pre-reduction in the pyrometallurgical process of nickel laterite ore is very limited,especially when using fluidized bed... Nickel laterite ore is an important nickel-bearing mineral.Research on pre-heating and hydrogen pre-reduction in the pyrometallurgical process of nickel laterite ore is very limited,especially when using fluidized bed roasting.This study systematically explores the mechanisms of fluidized bed pre-heating treatment and hydrogen pre-reduction in the roasting process of saprolitic nickel laterite ore.According to single-factor experiment results,the appropriate pre-heating and pre-reduction conditions were a pre-heating temperature of 700℃,a pre-heating time of 30 min,a pre-reduction temperature of 700℃,a pre-reduction time of 30 min,and a hydrogen concentration of 80%.Then,the nickel metallization rate and iron metallization rate reached 90.56%and 41.31%,respectively.Various analytical and testing methods were employed to study the changes in phase composition,magnetism,surface element valence states,and microstructure of nickel laterite ore during fluidized pre-heating and pre-reduction.The study shows that hydrogen can achieve nickel reduction at relatively low temperatures.It was also found that pre-heating treatment of nickel laterite ore is beneficial.Pre-heating opens up the mineral structures of serpentine and limonite,allowing the reducing gas and nickel to interact quickly during the reduction process,enhancing the pre-reduction process. 展开更多
关键词 nickel laterite ore FLUIDIZATION hydrogen pre-reduction phase transformation microstructure
在线阅读 下载PDF
Phase transformation behavior of galena during oxygen pressure leaching in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system
3
作者 SUN Pu BAO Chong-jun +4 位作者 WANG Ji-bo LI Xing-bin WEI Chang DENG Zhi-gan LI Min-ting 《Journal of Central South University》 2025年第8期2894-2911,共18页
The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosi... The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosite(Pb-J)were 130℃,30 g/L H_(2)SO_(4),15 g/L Fe^(3+),and an oxygen partial pressure of 0.4 MPa.Furthermore,increased Fe^(3+)concentration and oxygen partial pressure did not enhance jarosite formation.Conversely,lowering the temperature and increasing the H_(2)SO_(4) concentration facilitated PbSO_(4) formation and inhibited its further conversion to Pb-J.Additionally,the effects of potassium sulfate,sodium sulfate,and high concentrations of zinc sulfate on the phase transformation of galena were examined through leaching tests,XRD,SEM-EDS,and FT-IR analyses.All three sulfates inhibited the conversion of galena to Pb-J.Among these,potassium sulfate prevented Pb-J formation and converted it more thoroughly into potassium jarosite.However,high concentrations of zinc sulfate facilitated the crystallization of both PbSO_(4) and Pb-J,which altered the morphology of the product.Zinc ions coprecipitated with Pb-J,thereby integrating into the product. 展开更多
关键词 GALENA phase transformation lead sulfate lead jarosite oxygen pressure leaching
在线阅读 下载PDF
Development of an efficient and expedited cotyledon protoplast-based transient transformation system in Gossypium hirsutum L.
4
作者 WANG Zhicheng CAO Shuaiting +6 位作者 CAI Qiuyan GUAN Zhenhui CHENG Hailiang PENG Fanjia LI Yujun ZUO Dongyun SONG Guoli 《Journal of Cotton Research》 2025年第3期352-364,共13页
Background Cotton is an important crop providing the most natural fibers all over the world. The cotton genomics community has utilized whole genome sequencing data to construct an elite gene pool in which functional ... Background Cotton is an important crop providing the most natural fibers all over the world. The cotton genomics community has utilized whole genome sequencing data to construct an elite gene pool in which functional genes are related to agronomic traits. However, the functional validation of these genes is hindered by time-consuming and inefficient genetic transformation methods. Thus, establishing a transient transformation system of high efficiency is necessary for cotton genomics.Results To improve the efficiency of transient transformation, we used the protoplasts isolated from the etiolated cotyledon as recipient. The enzymatic digestion buffer comprised 1.5%(w/v) cellulase, 0.75%(w/v) macerozyme, and 1% hemicellulase, osmotically buffered with 0.4 mol·L^(-1) mannitol. After 5 h of dark incubation at 25℃, uniform cotton protoplasts were successfully isolated with a yield of 4.6 × 10^(6) protoplasts per gram(fresh weight) and 95% viability. We incubated 100 μL protoplasts(2.5 × 10^(5)·m L^(-1)) with 15 μg plasmid in the solution of 0.4 mol·L^(-1) mannitol and 40% PEG 4000 for 15 min, ultimately achieving an optimal transient transfection efficiency of 71.47%.Conclusions This transient system demonstrated effective utility in cellular biology research through successful applications in subcellular localization analyses, bimolecular fluorescence complementation(Bi FC) verification, and prime editing vector validation. Through systematic optimization, we established an efficient and expedited protoplast-based transient transformation system and successfully applied this platform to cotton functional genomics studies. 展开更多
关键词 Cotton Cotyledon protoplast-based transient transformation Prime editing Protoplast isolation Transient expression
在线阅读 下载PDF
Atomic-scale understanding of martensitic transformation and transition-induced twinning in deformed Fe-Mn alloys
5
作者 ZHANG Hong-bo LI Hong-kui +2 位作者 OU Xiao-qin SHEN Jie SONG Min 《Journal of Central South University》 2025年第4期1211-1222,共12页
In the present study,molecular dynamic simulation(MD)was used to investigate the plastic deformation process of the Fe-Mn alloys with different Mn contents.The influences of Mn contents ranging from 10%to 30%(at%)on t... In the present study,molecular dynamic simulation(MD)was used to investigate the plastic deformation process of the Fe-Mn alloys with different Mn contents.The influences of Mn contents ranging from 10%to 30%(at%)on the deformation behavior and the controlling mechanism of the Fe-base alloys were analyzed.The results show that phase transformations and{112}<111>_(BCC)deformation twinning occur in all Fe-Mn alloys but follow different deformation paths.In the Fe-10%Mn alloy the deformation twinning mechanism obeys the FCC-related path,the Fe-20%Mn alloy involves both the FCC-and HCP-related paths,and the deformation of the Fe-30%Mn alloy is dominated by the HCP-related twinning path.The addition of Mn can increase the stacking fault energy and retard the activation of slip systems as well as the formation of stacking faults.Thus,a higher content of Mn can delay the FCC®ε-martensite and the subsequentε-martensite®BCC phase transition at the intersection of twoε-martensitic bands.Therefore,the addition of Mn alloying element increases the yield strength and reduces the elastic modulus of the Fe-Mn alloys.The formation of deformation twins will contribute to the work-hardening effect and delay the necking and fracture of alloys.It is expected that the results in the present study will provide theoretical reference for the design and optimization of high-performance steels. 展开更多
关键词 Fe-Mn steel tensile deformation molecular dynamics simulation phase transformation
在线阅读 下载PDF
Gram-scale synthesis of simple cubic phase black phosphorus via shock-induced phase transformation:Mechanistic insights and process-dependent phase control
6
作者 Jinchao Qiao Qiang Zhou +9 位作者 Rufei Qiao Zhuwen Lyu Longhai Zhong Tianchu Wang Yan Liu Junbo Yan Fan Bai Xin Gao Pengwan Chen Peng Si 《Defence Technology(防务技术)》 2025年第11期293-308,共16页
Simple cubic black phosphorus(BP)has been recognized as a strategic material due to its exceptional structural stability under extreme conditions.In this investigation,simple cubic BP was successfully synthesized thro... Simple cubic black phosphorus(BP)has been recognized as a strategic material due to its exceptional structural stability under extreme conditions.In this investigation,simple cubic BP was successfully synthesized through shock-induced phase transformation,utilizing amorphous red phosphorus as the precursor material.The phase evolution process was systematically investigated using plane shock loading apparatus,with shock pressure and temperature parameters being precisely controlled to optimize transformation kinetics.Comprehensive phase characterization revealed the correlation between thermodynamic loading profiles and cubic BP formation efficiency.Precursor modification strategies were implemented through orthorhombic BP utilization,resulting in enhanced cubic phase yield and crystallinity.The synthesized cubic BP variants are considered promising candidates for advanced protective material systems,particularly where combinations of mechanical resilience and thermal stability are required under extreme operational conditions.This research provides critical insights into shock-induced phase transformation mechanics,while establishing foundational protocols for manufacturing non-equilibrium materials with potential applications in next-generation defensive technologies. 展开更多
关键词 Shock-induced phase transformation Orthorhombic black phosphorus Rhombohedral black phosphorus Simple cubic black phosphorus Shock-wave engineered materials Pressure-responsive polymorphs
在线阅读 下载PDF
Isothermal and athermal martensitic transformations of ceria cerla doped zilrconian 被引量:1
7
作者 音田哲彦 原纯平 +1 位作者 陈中春 早川元造 《材料与冶金学报》 CAS 2010年第3期211-216,共6页
Martensitic transformation behavior was studied for zirconia containing 4%~10% CeO2 (in mole fraction) by using a dilatometric method. The Ms (Martensite start temperature) decreased near linearly with increasing CeO... Martensitic transformation behavior was studied for zirconia containing 4%~10% CeO2 (in mole fraction) by using a dilatometric method. The Ms (Martensite start temperature) decreased near linearly with increasing CeO2. Different transformation modes were observed depending on the composition and cooling rate. ZrO2 containing 6% CeO2 showed isothermal transformation behavior, whereas ZrO2 containing 9% and 10% CeO2 showed athermal transformation behavior. However, ZrO2 containing 8% CeO2 showed either isothermal or athermal transformations behavior depending on the cooling rate. A TTT (Time-Temperature-Transformation) diagram was proposed for ZrO2 containing 8% CeO2. 展开更多
关键词 martensitic transformation ceria doped zirconia isothermal transformation athermal transformation thermally activated process burst type transformation
在线阅读 下载PDF
Hydration transformation behaviors of CO_(2) and excellent anti-inflammatory activity on RAW 264.7 cell
8
作者 Wanping Zhang Yiting Gu +3 位作者 Xuyan Li Zhiyong Sun Chunhong Wei Dongmei Zhang 《日用化学工业(中英文)》 CAS 北大核心 2024年第11期1289-1297,共9页
Skin care products with carbonic acid(H_(2)CO_(3))have gained extensive attention worldwide.However,the conversion of CO_(2) to H_(2)CO_(3) is not stable,and the mechanism of the effect of H_(2)CO_(3) on skin care has... Skin care products with carbonic acid(H_(2)CO_(3))have gained extensive attention worldwide.However,the conversion of CO_(2) to H_(2)CO_(3) is not stable,and the mechanism of the effect of H_(2)CO_(3) on skin care has not been clearly proved.The hydration-dissolution behaviors of CO_(2) were investigated under different temperature,pH,and pressure conditions.Moreover,based on the phenomenon of CO_(2) hydration transformation,the inflammatory effect of CO_(2) hydrate on macrophages(RAW 264.7)was investigated.The result shows that the increase in temperature weakened the hydration of CO_(2),and the increase in pH and pressure both promoted the water-phase transformation of CO_(2).When pH<6,CO_(2) reacts with water to generate H_(2)CO_(3).When pH was between 6-7,the prompt solution was a mixture of H_(2)CO_(3) and HCO_(3)^(-).When the pH was between 7-9,they mainly generated HCO_(3)^(-).And when pH>9,CO_(2) solubility mainly converts to CO_(3)^(2-).Besides,CO_(2) can inhibit the secretion of inflammatory factors by RAW 264.7 cells by inhibiting the phosphorylation of the p38 protein.CO_(2) hydrate inhibited the expression of pro-inflammatory factors IL-6,TNF-α,and up-regulated the expression of anti-inflammatory factor IL-10.Furthermore,the anti-inflammatory molecular mechanism of CO_(2) hydration inhibited the MAPK signaling pathway by inhibiting the phosphorylation of p38.The hydration-dissolution behavior of CO_(2) was investigated.This work revealed the anti-inflammatory bioeffect of CO_(2) hydrate,providing a theoretical basis and application support for CO_(2) skin care products. 展开更多
关键词 CO_(2) hydration transformation anti-inflammatory effect skin care
在线阅读 下载PDF
Fourier and wavelet transformations application to fault detection of induction motor with stator current 被引量:6
9
作者 LEE Sang-hyuk 王一奇 SONG Jung-il 《Journal of Central South University》 SCIE EI CAS 2010年第1期93-101,共9页
Fault detection of an induction motor was carried out using the information of the stator current. After synchronizing the actual data, Fourier and wavelet transformations were adopted in order to obtain the sideband ... Fault detection of an induction motor was carried out using the information of the stator current. After synchronizing the actual data, Fourier and wavelet transformations were adopted in order to obtain the sideband or detail value characteristics under healthy and various faulty operating conditions. The most reliable phase current among the three phase currents was selected using an approach that employs the fuzzy entropy measure. Data were trained with a neural network system, and the fault detection algorithm was verified using the unknown data. Results of the proposed approach based on Fourier and wavelet transformations indicate that the faults can be properly classified into six categories. The training error is 5.3×10-7, and the average test error is 0.103. 展开更多
关键词 Fourier transformation wavelet transformation induction motor fault detection
在线阅读 下载PDF
北京大学-北海道大学新一代物质转换工程共同研究室(Peking University -Hokkaido UniversityJoint Lab.on Next Generation Process forMaterial Transformation)研究室及博士后招收介绍
10
作者 席振峰 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 1999年第S1期545-545,共1页
关键词 transformation 研究室 转换工 北京大学 博士后工作 博士后研究人员 日本北海道 大学化学 Process 过渡金属有机化合物
在线阅读 下载PDF
Special Issue“Genome Editing and Genotype-independent Transformation Methodologies in Crop Improvement”
11
《生物技术通报》 CAS CSCD 北大核心 2023年第10期I0001-I0001,共1页
In this special issue,we plan to publish articles covering the following topics:Timely review(s);Research articles;Brief communications;and Step-by-step protocol(s)for methodology development in genome editing,in eith... In this special issue,we plan to publish articles covering the following topics:Timely review(s);Research articles;Brief communications;and Step-by-step protocol(s)for methodology development in genome editing,in either plant or mammalian cells;Genotype-independent transformation of crop species;Exploring the potential mechanisms underlying the differences in transformation. 展开更多
关键词 transformation. GENOME transformation
在线阅读 下载PDF
Phase transformation in suspension roasting of oolitic hematite ore 被引量:8
12
作者 李艳军 王儒 +1 位作者 韩跃新 魏新超 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第12期4560-4565,共6页
Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore.An oolitic hematite ore was roasted using suspension roasting technology at different temperatures.The phase tr... Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore.An oolitic hematite ore was roasted using suspension roasting technology at different temperatures.The phase transformation for iron minerals was investigated by XRD and Mossbauer spectrum,and the characteristics of roasted product were analyzed by VSM and SEM-EDS.Results indicate that the magnetic concentrate is of 58.73% Fe with iron recovery of 83.96% at 650 °C.The hematite is rapidly transformed into magnetite during the roasting with transformation ratio of 92.75% at 650 °C.Roasting temperature has a significant influence on the phase transformation of hematite to magnetite.The transformation ratio increases with increased temperature.After roasting,the magnetic susceptibility is significantly improved,while iron ore microstructure is not altered significantly. 展开更多
关键词 oolitic hematite ore suspension roasting Mossbauer spectrum magnetic property phase transformation
在线阅读 下载PDF
Siderite pyrolysis in suspension roasting:An in-situ study on kinetics,phase transformation,and product properties 被引量:6
13
作者 ZHANG Qi SUN Yong-sheng +2 位作者 QIN Yong-hong GAO Peng YUAN Shuai 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期1749-1760,共12页
Siderite,as an abundant iron ore,has not been effectively utilized,with a low utilization rate.In this study,the in-situ kinetics and mechanism of siderite during suspension magnetization roasting(SMR)were investigate... Siderite,as an abundant iron ore,has not been effectively utilized,with a low utilization rate.In this study,the in-situ kinetics and mechanism of siderite during suspension magnetization roasting(SMR)were investigated to improve the selective conversion of siderite to magnetite and CO,enriching the theoretical system of green SMR using siderite as a reductant.According to the gas products analyses,the peak value of the reaction rate increased with increasing temperature,and its curves presented the feature of an early peak and long tail.The mechanism function of the siderite pyrolysis was the contraction sphere model(R_(3)):f(α)=3(1−α)2/3;E_(α)was 46.4653 kJ/mol;A was 0.5938 s^(−1);the kinetics equation was k=0.5938exp[−46.4653/(RT)].The in-situ HT-XRD results indicated that siderite was converted into magnetite and wüstite that exhibited a good crystallinity in SMR under a N_(2) atmosphere.At 620℃,the saturation magnetization(M_(s)),remanence magnetization(Mr),and coercivity(Hc)of the product peaked at 53.63×10^(-3)A·m^(2)/g,10.23×10^(-3)A·m^(2)/g,and 12.40×10^(3)A/m,respectively.Meanwhile,the initial particles with a smooth surface were transformed into particles with a porous and loose structure in the roasting process,which would contribute to reducing the grinding cost. 展开更多
关键词 SIDERITE suspension magnetization roasting reaction kinetics phase transformation magnetic transition microstructure evolution
在线阅读 下载PDF
Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus at 65 °C 被引量:4
14
作者 夏金兰 赵小娟 +7 位作者 梁长利 杨益 聂珍媛 汤露 马陈燕 郑雷 赵屹东 邱冠周 《Journal of Central South University》 SCIE EI CAS 2012年第7期1961-1966,共6页
Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus (S. metallicus) at 65 ℃ was investigated by X-ray diffraction (XRD), diffuse re... Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus (S. metallicus) at 65 ℃ was investigated by X-ray diffraction (XRD), diffuse reflectance Fourier transform infrared spectroscopy (FT-IR) and sulfur K-edge X-ray absorption near edge structure spectroscopy (XANES). The results show that the presence of S. metallicus effectively enhances the dissolution of the mineral. The yield of zinc increases from 0.5 g/L in sterile control to 2.7 g/L in bioleaching. The pyrite in the concentrate facilitates zinc dissolution in the early stage, but has hindrance role in the late stage for the formation of jarosite. Sulfur speciation analyses show that jarosite and elemental sulfur are main products in bioleaching process, and the accumulation ofjarosite is mainly responsible for the decline of leaching efficiency. 展开更多
关键词 SPHALERITE BIOLEACHING Sulfolobus metallicus sulfur K-edge X-ray absorption near edge spectroscopy (XANES) sulfurspeciation transformation
在线阅读 下载PDF
A novel shapelet transformation method for classification of multivariate time series with dynamic discriminative subsequence and application in anode current signals 被引量:3
15
作者 WAN Xiao-xue CHEN Xiao-fang +2 位作者 GUI Wei-hua YUE Wei-chao XIE Yong-fang 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第1期114-131,共18页
Classification of multi-dimension time series(MTS) plays an important role in knowledge discovery of time series. Many methods for MTS classification have been presented. However, most of these methods did not conside... Classification of multi-dimension time series(MTS) plays an important role in knowledge discovery of time series. Many methods for MTS classification have been presented. However, most of these methods did not consider the kind of MTS whose discriminative subsequence was not restricted to one dimension and dynamic. In order to solve the above problem, a method to extract new features with extended shapelet transformation is proposed in this study. First, key features is extracted to replace k shapelets to calculate distance, which are extracted from candidate shapelets with one class for all dimensions. Second, feature of similarity numbers as a new feature is proposed to enhance the reliability of classification. Third, because of the time-consuming searching and clustering of shapelets, distance matrix is used to reduce the computing complexity. Experiments are carried out on public dataset and the results illustrate the effectiveness of the proposed method. Moreover, anode current signals(ACS) in the aluminum reduction cell are the aforementioned MTS, and the proposed method is successfully applied to the classification of ACS. 展开更多
关键词 anode current signals key features distance matrix feature of similarity numbers shapelet transformation
在线阅读 下载PDF
Theoretical Model of Transformation Superlastic Diffusion Bonding for Eutectoid Steel 被引量:2
16
作者 LU Shi-hong, YUN Jun-bi (College of Mechanic and Electricial Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期13-14,共2页
Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is ... Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is mainly described as two-stage process: Ⅰ The interfacial cavity with shape change from diamond to cylinder.Ⅱ The radius of the cylindrical cavity are reduced and eliminated gradually. A new theoretical model is established for the process of transformation superplastic diffusion bonding (TSDB) on the basis of a theoretical model for isothermal superplastic diffusion. The model can predict the bonding quality which is affected by technological parameters, such as limit cycling temperature, the compressive stress, the numbers of thermal cycles and temperature cycling through the phase transformation in the thermal cycling and so on. Results show that the maximum temperature, the compressive stress, the numbers of thermal cycles and the rate of temperature changing speed in the thermal cycling have an important influence on TSDB process. Meanwhile, reasonable technological parameters chosen from theoretical analysis is in good agreement with those obtained from experimental results. 展开更多
关键词 TSDB eutectoid steel phase transformation SUPERPLASTICITY diffusion bonding theoretical model
在线阅读 下载PDF
Spectral transformation-based technique for reducing effect of limited pre-correlation bandwidth in the GNSS receiver filter in presence of noise and multipath 被引量:2
17
作者 TITOUNI Salem ROUABAH Khaled +3 位作者 ATIA Salim FLISSI Mustapha MEZAACHE Salaheddine BOUHLEL Mohamed Salim 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2020年第2期252-265,共14页
This paper proposes an efficient scheme to reduce the pre-correlation bandwidth effect in the global navigation satellite system(GNSS)receiver filtering process.It is mainly based on the application of a spectral tran... This paper proposes an efficient scheme to reduce the pre-correlation bandwidth effect in the global navigation satellite system(GNSS)receiver filtering process.It is mainly based on the application of a spectral transformation to the satellite-emitted signal that effectively reduces its band.At the receiver's end,this operation causes the spreading of noise over a much wider band than that used by the radio frequency stage.Consequently,the resulting auto-correlation function in the acquisition process acquires properties that enhance considerably the performance of the receiver in the presence of the multipath and noise disturbing phenomena.The simulation results demonstrate that the proposed method is a plausible solution for both multipath and noise problems in the GNSS applications for any limited value of the pre-correlation bandwidth in the receiver filter. 展开更多
关键词 precorrelation BANDWIDTH spectral transformation MULTIPATH noise
在线阅读 下载PDF
Stability of GM(1,1) power model on vector transformation 被引量:2
18
作者 Jinhai Guo Xinping Xiao +1 位作者 Jun Liu Shuhua Mao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第1期103-109,共7页
The morbidity problem of the GM(1,1) power model in parameter identification is discussed by using multiple and rotation transformation of vectors. Firstly we consider the morbidity problem of the special matrix and... The morbidity problem of the GM(1,1) power model in parameter identification is discussed by using multiple and rotation transformation of vectors. Firstly we consider the morbidity problem of the special matrix and prove that the condition number of the coefficient matrix is determined by the ratio of lengths and the included angle of the column vector, which could be adjusted by multiple and rotation transformation to turn the matrix to a well-conditioned one. Then partition the corresponding matrix of the GM(1,1) power model in accordance with the column vector and regulate the matrix to a well-conditioned one by multiple and rotation transformation of vectors, which completely solve the instability problem of the GM(1,1) power model. Numerical results show that vector transformation is a new method in studying the stability problem of the GM(1,1) power model. 展开更多
关键词 grey power model STABILITY MORBIDITY vector transformation condition number of matrix
在线阅读 下载PDF
Super long-range diffusion of carbon during proeutectoid ferrite transformation 被引量:2
19
作者 ZHANG Suo-quan JIAO Si-hai +3 位作者 DING Jian-hua WAN Di LIU Zhen-yu WANG Guo-dong 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第3期560-566,共7页
In order to explore the possible diffusion distance of carbon during proeutectoid ferrite transformation, a slow cooling test of low carbon steel was carried out under vacuum of the thermal simulator. The microstructu... In order to explore the possible diffusion distance of carbon during proeutectoid ferrite transformation, a slow cooling test of low carbon steel was carried out under vacuum of the thermal simulator. The microstructure and thermal expansion curve were discussed and the carbon concentration inside the sample was measured. The ferrite layer of about 450 μm thickness was obtained without pearlite on the surface of the sample in the microstructure. The thermal expansion curve shows that the ferrite layer without pearlite is formed during the local phase transformation, which is followed by the global transformation. The carbon concentration in the core of the sample (0.061%) is significantly higher than that of the bulk material (0.054%). All results show that carbon has long-range diffusion from the outer layer to the inner layer of the sample. The transformation is predominantly interface-controlled mode during local transformation, and the interface migration rate is about 2.25 μm/s. 展开更多
关键词 low carbon steel local transformation super long-rang diffusion interface-controlled mode
在线阅读 下载PDF
Period of Arnold transformation and its application in image scrambling 被引量:2
20
作者 LI Bing XU Jia-wei 《Journal of Central South University of Technology》 2005年第z1期278-282,共5页
With the security problem of image information as the background, some more properties of the period of Arnold transformation of two-dimension were studied by means of introducing a integer sequence. Some new resuits ... With the security problem of image information as the background, some more properties of the period of Arnold transformation of two-dimension were studied by means of introducing a integer sequence. Some new resuits are obtained. Two interesting conjectures on the period of Arnold transformation are given. When making digital images scrambling by Arnold transformation, it is important to know the period of the transformation for the image. As the application of the theory, a new method for computing the periods at last are proposed. 展开更多
关键词 DIGITAL IMAGE PERIOD dynamic system ARNOLD transformation SCRAMBLING transformation
在线阅读 下载PDF
上一页 1 2 108 下一页 到第
使用帮助 返回顶部