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OAM-Based Hybrid-Duplex Cognitive Frequency Hopping

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Journal of Communications and Information Networks 2020年第4期5卷 381-392页

作者： Liping Liang zan Li Wenchi Cheng Hailin Zhang State Key Laboratory of Integrated Services Networks Xidian UniversityXi’an 710071China

In cognitive radio networks,the jamming attacks,which have the same ability with secondary users(SUs)but access the licensed channels without considering the carrier sense multiple access protocol,can disguise a primary user(PU)or SU to occupy the licensed channels,thus resulting in failing to access the licensed channels for PUs and *** full/half duplex cognitive frequency hopping(CFH),where users sense the occupancy of licensed channels and then dynamically adjust the hopping parameters,can mitigate the hostile ***,due to the explosive growth of serves and data traffic,it is very difficult to significantly increase the anti-jamming results and achieve high capacities with full/half duplex CFH for both PUs and SUs in cognitive radio *** achieve efficient anti-jamming and high capacities for PUs and SUs,in this paper we propose the orbital angular momentum(OAM)-based hybrid-duplex CFH scheme,which jointly uses the half-duplex cooperative sensing and full-duplex transmission modes for PUs and SUs in cognitive radio *** the OAM-based hybrid-duplex CFH scheme,PUs and SUs can identify the occupancy of licensed channels with half-duplex fashion,thus significantly reducing the probability of signals ***,based on the sensing results,the signals are allowed to be transmitted and received by the same time-slots,carrier frequencies,and *** average capacities of PUs and SUs are derived,*** numerical results show that our proposed OAM-based hybrid-duplex CFH scheme can significantly increase the capacities of PUs and SUs in cognitive radio networks under hostile jamming attacks.

关键词： orbital angular momentum(OAM) hybrid duplex cognitive frequency hopping cognitive radio net-works anti-jamming

Organic Brønsted Acid-Catalyzed Stereoselective Cationic RAFT Polymerization:The Effect of RAFT Agents

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Chinese Journal of Polymer Science 2024年第6期42卷 711-717页

作者： Zheng-Yi Zhang zan Yang yun Liao Sai-Hu Liao Key Laboratory of Molecule Synthesis and Function Discovery(Fujian Province University) College of ChemistryFuzhou UniversityFuzhou350108China State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China Beijing National Laboratory for Molecular Sciences Beijing100190China

The tacticity of vinyl polymers is a key factor affecting the properties of ***,organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective cationic reversible addition-fragmentation chain transfer(RAFT)polymerizations of vinyl ethers,in which the use of RAFT agents could allow the control the molecular weight and tacticity of polymer products ***,the effect of RAFT agents on the tacticity-regulation remains elusive and lacks of *** this study,we synthesized four types of RAFT agents and evaluated their influence in the stereoselective cationic polymerization of isobutyl vinyl ether in the presence of PADI as a Brønsted acid catalyst,which unveils that the Z group of RAFT agents could not only affect the polydispersity of the products,but also exert a profound effect on the *** extensive screening of the RAFT agents,high stereoregularity(isotacticity,90%m)was obtained when using dithiocarbonate ester-type RAFT agents with a benzyloxy Z group.

关键词： Bronsted acid catalysis Stereoselective cationic polymerization RAFT polymerization Chain transfer agents Tacticity

STAT1 signaling is required for optimal Th1 cell differentiation in mice

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Chinese Science Bulletin 2010年第11期55卷 1032-1040页

作者： MA Da HUANG Hua HUANG zan The Key Laboratory of Developmental Genes and Human Disease of Education Ministry School of Basic Medical Science Southeast University Nanjing 210009 China Department of Cell Biology Neurology and Anatomy Stritch School of Medicine Loyola University Chicago Maywood IL 60153 USA

Although IFN-γ alone does not prime type I T helper cell (Th1) differentiation, the loss of IFN-γ signaling leads to impaired Th1 phenotype: IFN-γ receptor-deficient (Ifngr-/-) Th1 cells fail to permanently repress IL-4 expression. They can differentiate into IL-4-producing cells under Th2-inducing conditions. These observations suggest that IFN-γ signaling plays a critical role in si- lencing Il4 gene in Th1 cells and stabilizing Th1 phenotype. IFN-γ signaling has been further shown to inhibit IL-4 expression by inhibiting STAT6 phosphorylation. This work aims to study the mechanism by which STAT1, the downstream molecule that transduces IFN-γ signaling, may mediate suppression of IL-4 expression in Th1 cells. The results show that STAT1-deficient naive CD4+ T cells express a reduced level of IFN-γ as well as an elevated level of IL-4. These cells exhibit bias to differentiate into Th2 cells under unpolarized conditions. Under Th1-inducing conditions, STAT1-deficient naive CD4+ T cells show impaired Th1 differentiation: Stat1-/- Th1 cells express reduced levels of IFN-γ and T-bet. These cells also fail to repress the expression of IL-4 and GATA-3 and retain STAT6 signaling. More importantly, Stat1-/- Th1 cells can be effectively induced to differentiate into IL-4-producing cells under Th2-inducing conditions. Ectopic expression of T-bet in Stat1-/- Th1 cells dramatically represses their ability to do so and drastically restores IFN-γ expression, suggesting that STAT1 may inhibit IL-4 expression through T-bet. Finally, histone H3 acetylation (H3AC) and histone H3 K4 dimethylation (H3K4dim) were observed in two enhancer regions of Il4 gene locus in Stat1-/- Th1 cells, suggesting a permissive status of Il4 gene locus in these cells. Thus, this study reveals new mechanisms by which STAT1 signaling may mediate repression of Il4 gene in Th1 cells: upregulating T-bet that subsequently represses GATA3 and IL-4 expression, antagonizing STAT6 signaling, and inhibiting epigen

关键词： STAT1 Th1/Th2 房间 T 赌注 STAT6 信号 transduction

Secure NOMA and OMA coordinated transmission schemes in untrusted relay networks

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Science China(Information Sciences) 2021年第10期64卷 266-267页

作者： Lu LV zan LI Haiyang DING Jian CHEN State Key Laboratory of Integrated Services Networks Xidian University National Mobile Communications Research Laboratory Southeast University School of Information and Communications National University of Defense Technology

Dear editor,Safeguarding physical-layer non-orthogonal multiple access(NOMA) transmissions using relays has been received widespread attention [1, 2]. However, a relay may be datalevel untrusted and serve as an eavesdropper to decode its forwarded messages. Hence, information security needs to be guaranteed if an untrusted relay is involved.

关键词： Information Systems and Communication Service

Bistable Stochastic Resonance Enhanced 4-ary PAM Signal Detection under Low SNR

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China Communications 2019年第4期16卷 196-207页

作者： Linlin Liang Nina Zhang Haiyan Huang zan Li School of Telecommunications Engineering Xidian University Xianyang Detachment of Chinese Armed Police Force School of Electronic and Information Engineering Lanzhou Jiaotong University The Collaborative Innovation Center of Information Sensing and Understanding at Xidian University

To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.

关键词： 4-ary pulse amplitude modulated signal detection Low SNR Symbol error rate(SER) Bistable stochastic resonance(BSR)

Using the Prostate Imaging Reporting and Data System version 2 （PI-RIDS v2） to detect prostate cancer can prevent unnecessary biopsies and invasive treatment

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Asian Journal of Andrology 2018年第5期20卷 459-464页

作者： Chang Liu Shi-Liang Liu Zhi-Xian Wang Kai yu Chun-Xiang Feng zan Ke Liang Wang Xiao-Yong Zeng Department of Urology Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China Department of Radiology Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China

Prostate cancer （PCa） is one of the most common cancers among men globally. The authors aimed to evaluate the ability of the Prostate Imaging Reporting and Data System version 2 （PI-RADS v2） to classify men with PCa, clinically significant PCa （CSPCa）, or no PCa, especially among those with serum total prostate-specific antigen （tPSA） levels in the ＂gray zone＂（4-10 ng ml-1）. A total of 308 patients （355 lesions） were enrolled in this study. Diagnostic efficiency was determined. Univariate and multivariate analyses, receiver operating characteristic curve analysis, and decision curve analysis were performed to determine and compare the predictors of PCa and CSPCa. The results suggested that PI-RADS v2, tPSA, and prostate-specific antigen density （PSAD） were independent predictors of PCa and CSPCa. A PI-RADS v2 score L≥4 provided high negative predictive values （91.39% for PCa and 95.69% for CSPCa）. A model of PI-RADS combined with PSA and PSAD helped to define a high-risk group （PI-RADS score = 5 and PSAD L≥0 15 ng ml-1 cm-3, with tPSA in the gray zone, or PI-RADS score L≥4 with high tPSA level） with a detection rate of 96.1% for PCa and 93.0% for CSPCa while a low-risk group with a detection rate of 6.1% for PCa and 2.2% for CSPCa. It was concluded that the PI-RADS v2 could be used as a reliable and independent predictor of PCa and CSPCa. The combination of PI-RADS v2 score with PSA and PSAD could be helpful in the prediction and diagnosis of PCa and CSPCa and, thus, may help in preventing unnecessary invasive procedures.

关键词： diagnosis multiparametric magnetic resonance imaging prostate cancer Prostate Imaging Reporting and Data Systemversion 2 prostate-specific antigen prostate-specific antigen density

Effective bias reduction methods for passive source localization using TDOA and GROA

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Science China(Information Sciences) 2013年第7期56卷 97-108页

作者： HAO BenJian LI zan QI PeiHan GUAN Lei State Key Laboratory of Integrated Services Networks Xidian University

For passive source localization based on both TDOA and GROA, this paper proposes two bias reduction methods for the well-known Weighted-Least-Squares (WLS) estimator. We first derive the passive source localization bias from the two-step algebraic closed-form solution. This bias is found to be considerably larger than the Maximum Likelihood Estimator (MLE) and limits the WLS estimator's practical applications. In this paper, We develop two methods to reduce the bias. The first one called Bias-Subtraction-Method (BSM) directly subtracts the expected bias from the solution of the WLS estimator, and the second one called Bias-Reduction-Method (BRM) imposes a constraint to the equation error formulation to improve the source location estimate. The noise covariance matrix must be known exactly in calculating the expected bias in BSM, and we only need to know the structure of it in BRM. For far-field sources localization when the noise is Gaussian and not too large, both of the two proposed methods can reduce the localization bias effectively and achieve the Cramér-Rao Lower Bound (CRLB) performance very well, and the BRM almost has the same performance as the MLE estimator. Simulations corroborate the performance of the two proposed methods.

关键词： source localization bias reduction Time Differences of Arrival (TDOA) Gain Ratios of Arrival (GROA) Cramér-Rao Lower Bound (CRLB)

Oil production rate predictions for steam assisted gravity drainage based on high-pressure experiments

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Science China(Technological Sciences) 2013年第2期56卷 324-334页

作者： GUO Jia zan Cheng MA DeSheng SHI Lin State Key Laboratory of Enhanced Oil Recovery Research Institute of Petroleum Exploration and DevelopmentPetro China Key Laboratory of Thermal Science and Power Engineering of Ministry of Education Department of Thermal EngineeringTsinghua University State Key Laboratory of Enhanced Oil Recovery Research Institute of Petroleum Exploration and DevelopmentPetroChina

Dual-well steam assisted gravity drainage(SAGD) has significant potential for extra-heavy oil *** is conducting two dual-well SAGD pilot projects in the Fengcheng extra-heavy oil ***,direct predictions of the oil production rate by algebraic models rather than complex numerical models are of great importance for designing and adjusting the SAGD operations.A low-pressure scaled physical simulation was previously used to develop two separate theoretical models corresponding to the two different growth stages observed in the SAGD steam chambers,which are the steam chamber rising stage and the steam chamber spreading stage.A high-pressure scaled model experiment is presented here for one dual-well SAGD pattern to further improve the prediction models to reasonably predict oil production rates for full *** that significantly affect the oil recovery during SAGD were scaled for the model size based on the reservoir characteristics of the Fengcheng reservoir in *** results show the relationship between the evolution of the steam chamber and the oil production rate during the entire production ***-pressure scaled model test was used to improve the gravity drainage models by modifying empirical factors for the rising model and the depletion model.A new division of the SAGD production regime was developed based on the relationship between the oil production rate and the evolution of steam chamber.A method was developed to couple the rising and depletion models to predict oil production rates during the SAGD production,especially during the transition *** method was validated with experiment data and field data from the *** model was then used to predict the oil production rate in the Fengcheng reservoir in China and the Athabasca reservoir in Canada.

关键词： extra-heavy oil steam assisted gravity drainage (SAGD) physical simulation theoretical model

Low-Temperature Synthesis of Crystalline Inorganic/Metallic Nanocrystal-Halloysite Composite Nanotubes

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Chinese Journal of Chemistry 2014年第7期32卷 599-606页

作者： Cuiping Li Jiaqiang Wang Siquan Feng zan Liu Department of Applied Chemistry Key Laboratory of Medicinal Chemistry for Natural ResourceMinistry of EducationSchool of Chemical Science and TechnologyYunnan UniversityKunmingYunnan 650091China Kunming Cable Co. LtdKunmingYunnan 650100China

We have demonstrated a facile approach for the low-temperature synthesis of crystalline inorganic/metallic nanocrystal-halloysite composite nanotubes by employing the bulk controlled synthesis of inorganic/metallic nanocrystals on halloysite *** halloysite clay nanotubes can adsorb the target precursor and induce inorganic/metallic nanocrystals to grow in *** crystalline phase and morphology of the composite clay nanotubes is *** simply tuning the acidity of the titania sol,the crystalline titania-clay nanotubes with tunable crystalline phases of anatase,a mixture of anatase and rutile or rutile are *** approach is general and has been extended to synthesize the representative perovskite oxide(barium and strontium titanate)-halloysite composite *** nickel nanocrystal can also be grown on the surface of halloysite nanotubes at low *** traditional thermal treatment for crystallite transformation is not required,thus intact contour of halloysite nanotubes and the crystallinity structure of halloysite nanotubes can be *** combined properties from inorganic/metallic nanocrystal(high refractive index,high dielectric constant and catalytic ability)and the halloysite clay nanotubes are promising for applications such as photonic crystals,high-k-gate dielectrics,photocatalysis and purification.

关键词： composite nanotubes halloysite inorganic nanocrystal perovskite oxide low temperature synthesis