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A Dual-Satellite GNSS Positioning Algorithm of High Accuracy in Incomplete Condition

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China Communications 2016年第10期13卷 58-68页

作者： Bing Hou xiaolin zhang Shanghai Engineering Center for Microsatellites Shanghai 201203 China Beihang University Beijing 100191 China

Global navigation satellite system could provide accurate positioning results in signal complete condition. However, the performance is severe when signal denied, especially for the single-mode Bei Dou receiver. This paper proposes a dual-satellite positioning algorithm to promote the positioning performance in the satellite signal gap. The new algorithm utilizes the previous positioning data stored in complete condition to simplify the positioning equations. As the clock bias persists for a short period, this proposed method could work out accurate positioning results by only two visible satellites, without the need of computing the clock bias. Also, the Kalman filtering algorithm is used to smooth the trajectories, and improve the positioning results. During the incomplete period, only two satellites for 30 seconds and three satellites for 60 seconds, the preliminary experiment result shows that, the presented method could provide almost the same positioning results as in complete condition.

关键词： Bei Dou navigation satellite system incomplete condition dual-satellite positioning algorithm kalman filtering

Column adsorption of Cu(Ⅱ) by polymer-supported nano-iron oxides in the presence of sulfate: Experimental and mathematical modeling

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1163-1169页

作者： Hui Qiu xiaolin zhang Zhe Xu Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET) School of Environmental Science and Engineering Nanjing University of Information Science & Technology State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

Polymer-supported hydrous iron oxides(HFOs) are promising for heavy metals removal from aqueous *** ubiquitous inorganic ligands, e.g., sulfate, are expected to exert considerable impacts on pollutants removal by these hybrid sorbents. Herein, we obtained a hybrid sorbent HFO-PS by encapsulating nanosized HFO into macroporous polystyrene(PS) resin. Both batch and column sorption experiments of Cu(Ⅱ) by HFO-PS were carried out in the presence of sulfate. Obviously, the presence of sulfate is favorable for Cu(Ⅱ) sorption onto *** performances of column Cu(Ⅱ) removal were fitted and predicted with Adams–Bohart, Clark, Thomas and BDST models. Thomas model is suggested best-fit to predict the breakthrough curves. Besides, a linear correlation is observed between breakthrough time and column length based on BDST model, which might be useful for predicting the breakthrough time for Cu(Ⅱ) removal by HFO-PS.

关键词： Composite Nanotechnology Waste water Hydrous iron oxide Fixed-bed adsorption Thomas model

Quasinormal modes and late time tails of perturbation fields on a Schwarzschild-like black hole with a global monopole in the Einstein-bumblebee theory

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Science China(Physics,Mechanics & Astronomy) 2023年第10期66卷 33-43页

作者： xiaolin zhang Mengjie Wang Jiliang Jing School of Physics and Electronics Synergetic Innovation Center for Quantum Effects and Applicationsand Institute of Interdisciplinary StudiesHunan Normal UniversityChangsha 410081China

In this paper we complete a systematic study on quasinormal modes(QNMs) and late time tails for scalar,Dirac and Maxwell fields on a spherically symmetric Schwarzschild-like black hole with a global monopole in the Einstein-bumblebee *** look for QNMs,we solve the equations of motion for all perturbation fields considered herein numerically,by employing both the matrix and the WKB methods,and find good agreements for numeric data obtained by these two techniques in the regime when both are *** impact of the bumblebee parameter c,the monopole parameter η^(2),and the multipole number l on the fundamental quasinormal frequency are analyzed in *** results are shown in terms of the quasinormal frequency measured by √1+c M ,where M is a black hole mass *** observe,by increasing the parameter c(η^(2)) with fixed first few l,that the real part of QNMs increases for all spin fields;while the magnitude of the imaginary part decreases for scalar and Dirac fields but increases for Maxwell *** increasing the multipole numberlwith fixed other parameters,we disclose that the real part of QNMs for all spin fields increases while the magnitude of the imaginary part decreases for scalar and Dirac fields but increases for Maxwell *** the eikonal limit(l>>n),QNMs for all spin fields coincide with each other and the real part scale linearly with *** particular,the asymptotic QNMs approach the corresponding results given by the first order WKB formula,and only the real part of QNMs is dependent on the bumblebee and monopole *** addition,it is shown that the late time behavior is determined not only by the multipole number but also by the bumblebee and monopole parameters,and is distinct for bosonic and fermonic ***,the presence of the bumblebee(monopole) field makes the spin fields decay *** results indicate,both in the context of QNMs and late time tails,that the bumblebee field and the monopole field play the same ro

关键词： Einstein-bumblebee theory perturbation fields dynamic evolution

Modulation recognition of communication signals based on SCHKS-SSVM

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Journal of Systems Engineering and Electronics 2017年第4期28卷 627-633页

作者： xiaolin zhang Jian Chen Zhiguo Sun College of Information and Communication Engineering Harbin Engineering UniversityHarbin 150001China Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory Shijiazhuang 050000China

A novel modulation recognition algorithm is proposed by introducing a Chen-Harker-Kanzow-Smale (CHKS) smooth function into the C-support vector machine deformation algorithm. A set of seven characteristic parameters is selected from a range of parameters of communication signals including instantaneous amplitude, phase, and frequency. And the Newton-Armijo algorithm is utilized to train the proposed algorithm, namely, smooth CHKS smooth support vector machine (SCHKS-SSVM). Compared with the existing algorithms, the proposed algorithm not only solves the non-differentiable problem of the second order objective function, but also reduces the recognition error. It significantly improves the training speed and also saves a large amount of storage space through large-scale sorting problems. The simulation results show that the recognition rate of the algorithm can batch training. Therefore, the proposed algorithm is suitable for solving the problem of high dimension and its recognition can exceed 95% when the signal-to-noise ratio is no less than 10 dB.

关键词： communication signal modulation recognition support vector machine smooth function

Effect of sulfate on Cu(Ⅱ)sorption to polymer-supported nano-hydrated ferric oxides:Experimental and modeling studies

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Chinese Journal of Chemical Engineering 2021年第5期34卷 319-326页

作者： Wenxiang Ni Luyang Yang xiaolin zhang Hui Qiu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Jiangsu Key Laboratory of Atmospheric Environment Monitoring and PollutionControlSchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

Incorporating of hydrous ferric oxide(HFO)inside porous supports with large sizes has become an effective way to decontaminate the water from heavy *** anions like sulfate are usually present in high concentrations in water,and might greatly affect adsorption behavior of hybrid ***,a polymer-based HFO-CPS was fabricated by encapsulating nano-HFO inside a chloromethylated polystyrene polymer(CPS)and the reactivity of HFO-CPS with Cu(Ⅱ)was evaluated in the presence of sulfate *** complexation theory was firstly employed to describe the effect of sulfate on Cu(Ⅱ)adsorption edges of hybrid HFO-CPS,where constant capacitance model(CCM)was *** available weak adsorption site Fe_((2))OH of hybrid HFO-CPS was found to decrease from 20% Fe to 5% Fe,which might be caused by the pore plugging effect after HFO *** the assumption that a ternary complex was formed,the effect of sulfate on Cu(Ⅱ)adsorption by HFO-CPS were successfully described by CCM using the optimized Fe_((2))OH site under different sulfate concentrations(1 or 10 mmol·L^(-1))and Cu/Fe ratios(0.0042 or 0.0252).It is confirmed that the formation of FeOHCuSO4 ternary surface complexes played an important role in enhancing Cu(Ⅱ)adsorption on HFO-CPS in the presence of sulfate.

关键词： Iron oxides Polymer Sulfate Adsorption Ternary complex

Solid Bronsted acidity boosts adsorption reactivity of nano-adsorbent for water decontamination

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Frontiers of Environmental Science & Engineering 2024年第7期18卷 23-34页

作者： Sikai Cheng Zhixian Li Kaisheng zhang Qingrui zhang xiaolin zhang Bingcai Pan State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China Environmental Materials and Pollution Control Laboratory Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China Hebei Key Laboratory of Heavy Metal Deep-remediation in Water and Resource Reused Qinhuangdao 066004China Research Center for Environmental Nanotechnology(ReCENT) Nanjing UniversityNanjing 210023China

Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through innersphere coordination,strong competition for hydroxyl ions still hinders efficient water *** addition,the critical issue of polysilicate scaling that results from the ubiquitous silicates must be *** tackle these issues,an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Bronsted acidity is *** feasibility of this approach is demonstrated by growing zirconium phosphate(ZrP)inside a gel-type anion exchanger,N201,to produce nanocomposite ZrP@N201,in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr^(4+) sites and Bronsted acidic monohydrogen phosphate groups(-O_(3)POH).Compared with the Lewis acidic nano-zirconium oxide analog(HZ0@N201),ZrP@N201 exhibited a greatly improved adsorption capacity(117.9 vs.52.3 mg/g-Zr)and mass transfer rate(3.56×10^(-6) vs.4.55×10^(-7) cm/s),while bulk ZrP produced a thermodynamically stableα-phase with Bronsted acidity that exhibited negligible adsorption capability toward *** enhanced defluoridation activity of ZrP@N201 is attributed to Bronsted acidity and the increased outer electron density of ZA+sites,as corroborated using XPS and solid-state NMR ***,Bronsted acidity strengthens the resistance of ZrP@N201 to silicate,allowing its full regeneration during cyclic *** tests demonstrated 3-10 times the amount of clean water from(waste)for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum *** study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications.

关键词： Nanocomposite Selective adsorption Fluoride removal Dual Lewis and Bronsted acidity Regeneration

High Hardware Utilization and Low Memory Block Requirement Decoding of QC-LDPC Codes

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Chinese Journal of Aeronautics 2012年第5期25卷 747-756页

作者： ZHAO Ling LIU Rongke HOU Yi zhang xiaolin School of Electronics and Information Engineering Beihang UniversityBeijing 100191China

This paper presents a simple yet effective decoding for general quasi-cyclic low-density parity-check （QC-LDPC） codes, which not only achieves high hardware utility efficiency （HUE）, but also brings about great memory block reduction without any performance degradation. The main idea is to split the check matrix into several row blocks, then to perform the improved mes- sage passing computations sequentially block by block. As the decoding algorithm improves, the sequential tie between the two-phase computations is broken, so that the two-phase computations can be overlapped which bring in high HUE. Two over- lapping schemes are also presented, each of which suits a different situation. In addition, an efficient memory arrangement scheme is proposed to reduce the great memory block requirement of the LDPC decoder. As an example, for the 0.4 rate LDPC code selected from Chinese Digital TV Terrestrial Broadcasting （DTTB）, our decoding saves over 80% memory blocks com- pared with the conventional decoding, and the decoder achieves 0.97 HUE. Finally, the 0.4 rate LDPC decoder is implemented on an FPGA device EP2S30 （speed grade -5）. Using 8 row processing units, the decoder can achieve a maximum net throughput of 28.5 Mbps at 20 iterations.

关键词： wireless communication channel coding low-density parity-check (LDPC) codes decoding hardware utility effi-ciency overlapping

Structural and electronic properties of bastnaesite and implications for surface reactions in flotation

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Journal of Rare Earths 2020年第3期38卷 332-338页

作者： Shiming Cao Yijun Cao Zilong Ma Yinfei Liao xiaolin zhang School of Resources and Environmental Engineering Shandong University of TechnologyZibo 255000China National Engineering Research Center of Coal Preparation and Purification China University of Mining and TechnologyXuzhau 221116China Henan Province Industrial Technology Research Institute of Resources and Materials Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Complex Nonferrous Meal Resources Clean Utilization Kunming University of Science and TechnologyKunming 650093China

The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory(DFT).The geometry structure of bastnaesite was first optimized,and then the Mulliken populations,electron density and density of states were calculated and further analyzed in *** calculation results reveal that it mainly ruptures along the ionic Ce-O and Ce-F bonds during the cleavage of bastnaesite,leaving≡Ce^+,≡F^-and≡CO3^-dangling bonds exposed on the cleavage surface of *** with contact angle measurement,surface complexation theory and XPS analysis,the implications of structural and electronic properties on bastnaesite flotation reactions were *** hydration of exposed strong ionic bond on cleavage surface results in hydrophilic *** to surface complexation theory,the formed surface groups are≡CeOH^0,≡CO3 H^0 and≡FH^0 *** investigated metal ions and flotation reagents complex with surface≡CeOH^0 groups,while≡CO3H^0 and≡FH^0 groups are not involved in the *** high activity of Ce atoms facilitates these surface reactions.

关键词： Bastnaesite Density functional theory calculation Electronic property Flotation Rare earths

Fabrication of SmCo_(5) alloy via cobalt-induced calciothermic reduction and magnetic properties of its ribbon

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Journal of Rare Earths 2021年第5期39卷 572-578页

作者： Donghui Liu Fei Niu xiaolin zhang Yuning Meng Youming Yang Faculty of Materials Metallurgy and ChemistryJiangxi University of Science and TechnologyGanzhou 341000China Institute of Engineering Research Jiangxi University of Science and TechnologyGanzhou 341000China National Engineering Research Center for Ionic Rare Earth Ganzhou 341000China

SmCo_(5)alloy was prepared via direct calciothermic reduction using anhydrous samarium fluoride(SmF_(3))as raw material and cobalt as *** of the thermodynamic calculation show that the direct reduction of cobalt-induced SmF_(3)for preparing SmCo_(5)alloy is *** alloy with 33.89 wt%samarium and a yield of 96.45%were achieved under the optimal conditions of 10%and 20%excess of SmF_(3)and calcium over the stoichiometry,respectively,and 1450℃for 4 *** X-ray diffraction results show that the reduction products are SmCo_(5)alloy and CaF_(2).The scanning electron microscopy micrograph of the SmCo_(5)alloy ingot exhibits a distinct dendritic morphology composed of samarium and *** X-ray photoelectron spectroscopy shows that the atomic ratio of samarium to cobalt is approximately 1:5 and both elements demonstrate zero valency(Sm^(0),Co^(0)).The magnetic properties measurement of the SmCo_(5)alloy melt-spun ribbon shows the remanent magnetization B_r=0.59 T,intrinsic coercivity H_(Ci)=345.82 kA/m and maximum magnetic energy density(BH)_(max)=42.20 kJ/m^(3).These results may be helpful for the development of novel valence-variable rare-earth alloys.

关键词： Calciothermic reduction Cobalt-induced SmF_(3) SmCo_(5) Preparation Rare earths