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Determination of Iron in Layered Crystal Sodium Disilicate and Sodium Silicate by Flame Atomic Absorption Spectrometry with Boric Acid as a Matrix Modifier

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Chinese Chemical Letters 2006年第6期17卷 809-812页

作者： Zhi Hua wang Min cai Shu jun wang State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing 100029

The effects of matrix silicate and experimental conditions on the determination of iron in flame atomic absorption spectrometry （FAAS） were investigated. It was found that boric acid as a matrix modifier obviously eliminated silicate interference. Under the optimum operating conditions, the determination results of iron in layered crystal sodium disilicate and sodium silicate samples by FAAS were satisfactory. The linear range of calibration curve is 0-10.5 μ***^-1, the relative standard deviation of method is 1.2%-2.2%, the recovery of added iron is 96.0%- 101%, the sensitivity is 0.19 μ***^-l and the detection limit is 77 ***^-1. The effect of the determination of iron of the standard curve method, standard addition calibration and colorimetry method was the same, but the first has the merits of rapid sample preparation, reduced contamination risks and fast analysis.

关键词： Layered crystal sodium disilicate sodium silicate flame atomic absorption spectrometry determination of iron boric acid.

Numerical Simulation of Rogue Waves by the Local Discontinuous Galerkin Method

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Chinese Physics Letters 2014年第4期31卷 1-4页

作者： cai Wen-jun wang Yu-Shun SONG Yong-Zhong Jiangsu Provincial Key Laboratory for NSLSCS School of Mathematics and Sciences Nanjing Normal University Nanjing 210023

We study rogue waves described by nonlinear Schr6dinger equations. Such wave solutions are so different from conventional soliton solutions that classic methods such as the Crank-Nicolson scheme cannot work for these cases. Fortunately, we find that the local discontinuous Galerkin method equipped with Dirichlet boundary conditions can simulate rogue waves very well. Several numerical examples are presented to show such interesting wave solutions.

关键词： ROGUE waves SCHRODINGER equation SOLITONS GALERKIN methods DIRICHLET forms

Heuristic Genetic Algorithm for Discretization of Continuous Attributes in Rough Set Theory

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Journal of China University of Mining and Technology 2006年第2期16卷 147-150,155页

作者： CAO Yun-feng wang Yao-cai wang jun-wei School of Information and Electric Engineering China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

Discretization based on rough set theory aims to seek the possible minimum number of the cut set without weakening the indiscemibility of the original decision system. Optimization of discretization is an NP-complete problem and the genetic algorithm is an appropriate method to solve it. In order to achieve optimal discretization, first the choice of the initial set of cut set is discussed, because a good initial cut set can enhance the efficiency and quality of the follow-up algorithm. Second, an effective heuristic genetic algorithm for discretization of continuous attributes of the decision table is proposed, which takes the significance of cut dots as heuristic information and introduces a novel operator to maintain the indiscernibility of the original decision system and enhance the local research ability of the algorithm. So the algorithm converges quickly and has global optimizing ability. Finally, the effectiveness of the algorithm is validated through experiment.

关键词： rough set discretization genetic algorithm

Extending the trapping lifetime of single atom in a microscopic far-off-resonance optical dipole trap

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Frontiers of physics 2011年第3期6卷 262-270页

作者： jun HE Bao-dong YANG Yong-jie CHENG Tian-cai ZHANG jun-min wang State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto Electronics Shanxi University Taiyuan 030006 China

In our experiment, a single cesium atom prepared in a large-magnetic-gradient magneto optical trap （MOT） can be efficiently transferred into a 1064-nm far-off-resonance microscopic optical dipole trap （FORT）. The efficient transfer of the single atom between the two traps is used to determine the trapping lifetime and the effective temperature of the single atom in FORT. The typical trapping lifetime has been improved from ~ 6.9 s to ~ 130 s by decreasing the background pressure from 1 × 10^-10 Torr to ~ 2 × 10^-11 Torr and applying one-shot 10-ms laser cooling phase. We also theoretically investigate the dependence of trapping lifetimes of a single atom in a FORT on trap parameters based on the FORT beam＇s intensity noise induced heating. Numerical simulations show that the heating depends on the FORT beam＇s waist size and the trap depth. The trapping time can be predicted based on effective temperature measurement of a single atom in the FORT and the intensity noise spectra of the FORT beam. These experimental results are found to be in agreement with the predictions of the heating model.

关键词： magneto optical trap (MOT) far-off-resonance optical dipole trap (FORT) singleatom trapping lifetime release-and-recapture method (R&R) effective temperature

Condensing Heat Recovery of Centrifugal Chiller

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湖南大学学报（自然科学版） 2009年第S1期36卷 123-126页

作者： GONG Guang-cai,JIAO jun-jun,wang Li-ping,ZENG Wei(College of Civil Engineering,Hunan University,Changsha,Hunan 410082,China) College of Civil Engineering Hunan University Changsha 410082 China

To a kind of centrifugal water chiller with R22 and about 1 745 kW of cooling capacity,a heat exchanger was added between the outlet of compressor and original condenser to get part of or all the condensing *** heat can be recovered by compound condensing method,which adopts air-cooling model +water-cooling model or water-cooling model +water-cooling model at the condensing side of the *** exergy analysis and experiment research on compound condensing heat recovery of centrifugal chiller,the results are obtained that the capability of the whole system increases,the energy efficiency ratio(EER)becomes 3.2～5.0 from 2.2～3.4,which implies the EER increases about 1.0～1.5,the exergy efficiency increases about 10%,and the chiller runs more stably after reformation.

关键词： centrifugal chiller condensing heat recovery compound condensing method EER

Mitigating set-stuck failure in 3D phase change memory: substituting square pulses with surge pulses

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Science China(Information Sciences) 2024年第5期67卷 295-301页

作者： Ninghua LI wang cai jun XIANG Hao TONG Weiming CHENG Xiangshui MIAO School of Integrated Circuits Huazhong University of Science and Technology Hubei Yangtze Memory Laboratories Hubei Institute of Measurement and Testing Technology

In the devices that integrate phase change memory(PCM) and ovonic threshold switching(OTS),the OTS threshold voltage often surpasses the RESET operation voltage of PCM. The conventional application of square pulses hinders the successful completion of the SET operation in these integrated devices. To address this challenge, a novel pulse called the surge pulse is introduced, which comprises a high amplitude pulse for OTS activation and a low amplitude pulse for PCM operation. By employing COMSOL simulation,the operational effectiveness of both square pulses and surge pulses is validated. Test results reveal that using a square pulse to operate the integrated device accelerates the occurrence of SET-stuck failure(SSF).In contrast, the surge pulse enables the integrated device to operate for at least 1000 cycles while preserving the essential cyclic characteristics. Additionally, an investigation into the overshoot component of the surge pulse is conducted, revealing that an increase in overshoot amplitude and pulse width also accelerates the emergence of SSF. By applying the theory of ion migration induced by the electric field, the root cause of SSF in integrated devices is explained, and the accuracy of the theory is validated through the application of a reverse pulse. In summary, this study elucidates the rationality of replacing the square pulse with a surge pulse, presenting a superior approach for operating PCM and OTS integrated devices.

关键词： surge pulse phase change memory (PCM) integration SET-stuck failure (SSF) square pulse

Microstructural evolution and deformation behavior of friction stir welded twin-induced plasticity steel

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Journal of Materials Science & Technology 2024年第2期169卷 68-81页

作者： Ke Qiao Kuaishe wang Jia wang Zhengyang Hao Yating Xiang Peng Han jun cai Qi Yang Wen wang School of Metallurgical Engineering National and Local Joint Engineering Research Center for Functional Materials ProcessingXi’an University of Architecture and TechnologyXi’an 710055China Shanghai Research Institute of Materials Shanghai 200437China

The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first *** results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in *** with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,*** elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile *** engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the ***,the tensile fracture occurred in the *** order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈*** order of yield strength was as follows:HAZ>BM>SZ.

关键词： Twin-induced plasticity steel Friction stir welding Microstructure Mechanical property Deformation behavior

Optimization of resource allocation in FDD massive MIMO systems

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Digital Communications and Networks 2024年第1期10卷 117-125页

作者： jun cai Chuan Yin Youwei Ding School of Artificial Intelligence and Information Technology Nanjing University of Chinese MedicineNanjing 210046China School of Electronic and Information Hangzhou Dianzi UniversityHangzhou 310018ZhejiangChina

The performance of massive MIMO systems relies heavily on the availability of Channel State Information at the Transmitter(CSIT).A large amount of work has been devoted to reducing the CSIT acquisition overhead at the pilot training and/or CsI feedback *** fact,the downlink communication generally includes three stages,i.e.,pilot training,CsI feedback,and data *** three stages are mutually related and jointly determine the overall system ***,there exist few studies on the reduction of csIT acquisition overhead from the global point of *** this paper,we integrate the Minimum Mean Square Error(MMSE)channel estimation,Random Vector Quantization(RVQ)based limited feedback and Maximal Ratio Combining(MRC)precoding into a unified framework for investigating the resource allocation *** particular,we first approximate the covariance matrix of the quantization error with a simple expression and derive an analytical expression of the received Signal-to-Noise Ratio(SNR)based on the deterministic equivalence *** the three performance metrics(the spectral efficiency,energy efficiency,and total energy consumption)oriented problems are formulated *** practical system requirements,these three metrics can be collaboratively ***,we propose an optimization solver to derive the optimal partition of channel coherence *** results verify the benefits of the proposed resource allocation schemes under three different scenarios and illustrate the tradeoff of resource allocation between three stages.

关键词： Massive MIMO FDD CSIT Resource allocation

Quantifying freeze-melt dynamics of lakes on the Tibetan Plateau using Sentinel-1 synthetic aperture radar imagery

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Journal of Mountain Science 2024年第3期21卷 805-819页

作者： JIN Lu CHEN jun cai Yu KONG Yecheng wang Yongfeng DUAN Zheng School of Environment and Energy Engineering Anhui Jianzhu UniversityHefei 230601China Anhui Engineering and Technology Research Center for Smart City Anhui Jianzhu UniversityHefei 230601China School of Geographic and Oceanographic Sciences Nanjing UniversityNanjing 210023China Department of Physical Geography and Ecosystem Science Lund UniversityLund 22362Sweden

The ice phenology of alpine lakes on the Tibetan Plateau(TP)is a rapid and direct responder to climate changes,and the variations in lake ice exhibit high temporal frequency *** and passive microwave data are widely used to monitor lake ice changes with high temporal ***,the low spatial resolutions make it difficult to effectively quantify the freeze-melt dynamics of *** work used Sentinel-1 synthetic aperture radar(SAR)data to derive high-resolution ice maps(about 6 days),then with the aid of Sentinel-2 optical images to quantify freeze-melt processes in three typical lakes on the TP(*** Co,Ayakekumu Lake,and Nam Co).The results showed that three lakes had an average annual ice period of 125-157 days and a complete ice cover period of 72-115 days,from 2018 to *** exhibit different ice phenology *** Co is characterized by repeated episodes of freezing,melting,and refreezing,resulting in a prolonged freeze-up ***,the break-up period of Nam Co lasts for a longer duration(about 19 days),and the break-up exhibits a smooth ***,Ayakekumu Lake showed more significant inter-annual fluctuations in the freeze-up period,with deviations of up to 28 days observed among different *** to the other two lakes,Selin Co experienced a relatively short freeze-up and break-up *** short,Sentinel-1 SAR data can effectively monitor the weekly and seasonal variations in lake ice on the ***,this data facilitates quantification of the freeze-melt dynamics.

关键词： Lake ice Sentinel-1 SAR Tibetan Plateau Climate change