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Impact of receiver inter-frequency bias residual uncertainty on dual-frequency GBAS Integrity

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Chinese Journal of Aeronautics 2022年第11期35卷 349-362页

作者： Kai KANG Kun FANG Yanbo ZHU Yuan LIU Zhipeng WANG Qiang LI National Key Laboratory of CNS/ATM School of Electronic and Information EngineeringBeihang UniversityBeijing 100083China Research Institute for Frontier Science Beihang UniversityBeijing 100083China

Dual-Frequency Ground-Based Augmentation Systems(GBAS)can be affected by receiver Inter-Frequency Bias(IFB)when Ionosphere-Free(Ifree)smoothing is applied.In the framework of the proposed GBAS Approach Service Type F(GAST-F),the IFB in the Ifree smoothed pseudorange can be corrected.However,IFB residual uncertainty still exists,which may threaten the Integrity of the system.This paper presents an improved algorithm for the airborne protection level considering the residual uncertainty of IFBs to protect the Integrity of dual-frequency GBAS.The IFB residual uncertainty multiplied by a frequency factor is included in the Ifree protection level together with the uncertainty of other error sources.To verify the proposed protection level algorithm,we calculate the IFB residual uncertainties of ground reference receivers and user receiver based on BDS B1I and B3I dual-frequency observation data and carry out a test at the Dongying Airport GBAS station.The results show that the proposed Ifree protection level with IFB residual uncertainty is 1.48 times the current protection level on average.The probability of Misleading Information(MI)during the test is reduced from 3.2×10^(-4)to the required value.It is proven that the proposed protection level can significantly reduce the Integrity risk brought by IFB residual uncertainty and protect the Integrity of dual-frequency GBAS.

关键词： GBAS Integrity Inter-frequency bias Ionosphere-free smoothing Vertical protection level

An Investigation into the Effects of Oil-Well Cement Expansion Agent on the Integrity of Cement Sheath

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Fluid Dynamics & Materials Processing 2023年第5期19卷 1291-1300页

作者： Chunqin Tan Shenglai Guo Juanjuan Huang Sinopec Research Institute of Petroleum Engineering Beijing100101China Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580China School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580China E&D Research Institute of Liaohe Oilfield Company Panjin124000China

Generally,the so-called expansion agent is very effective in eliminating all the micro-annuli that exist between the casing and the cement sheath or between the cement sheath and the formation.However,this approach can detrimentally affect the sealing ability of cement sheath if the expansion agent is used in an unreasonable way.For these reasons,in the present work,numerical simulations have been conducted to analyze the effect of elasticity modulus of cement sheath,the elasticity modulus of formation,the expansion rate of cement,the geo-stress on the micro-annulus caused by cement expansion,and the cement sheath expansion on the Integrity of cement sheath and formation.The micro-annulus between the casing and the cement sheath has been found to decrease according to the ratio between the elasticity modulus of formation and the elasticity modulus of cement sheath.A positive correlation has been observed between the micro-annulus and the cement expansion ratio.The microannulus decreases as the geo-stress increases,but the effect of the geo-stress on the micro-annulus is much smaller.In conclusion,the expansion agent is suitable for the formation in which the elasticity modulus is higher than the cement sheath.

关键词： Cement sheath expansion agent numerical simulation Integrity

Superior intestinal Integrity and limited microbial translocation are associated with lower immune activation in SIVmac239-infected northern pig-tailed macaques(Macaca leonina)

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Zoological Research 2019年第6期40卷 522-531页

作者： Ming-Xu Zhang Tian-Zhang Song Hong-Yi Zheng Xue-Hui Wang Ying Lu Han-Dan Zhang Ting Li Wei Pang Yong-Tang Zheng Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province National Kunming High Level Biosafety Research Center for Non-human PrimatesKIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common DiseasesKunming Institute of ZoologyChinese Academy of SciencesKunming Yunnan 650223China Kunming College of Life Science University of Chinese Academy of SciencesKunming Yunnan 650204China School of Life Sciences University of Science and Technology of ChinaHefei Anhui 230026China KIZ-SU Joint Laboratory of Animal Models and Drug Development College of Pharmaceutical SciencesSoochow UniversitySuzhou Jiangsu 215123China

Microbial translocation is a cause of systemic immune activation in HIV/SIV infection. In the present study, we found a lower CD8+ T cell activation level in Macaca leonina (northern pig-tailed macaques, NPMs) than in Macaca mulatta (Chinese rhesus macaques, ChRMs) during SIVmac239 infection. Furthermore, the levels of plasma LPS-binding protein and soluble CD14 in NPMs were lower than those in ChRMs. Compared with ChRMs, SIV-infected NPMs had lower Chiu scores, representing relatively normal intestinal mucosa. In addition, no obvious damage to the ileum or colon epithelial barrier was observed in either infected or uninfected NPMs, which differed to that found in ChRMs. Furthermore, no significant microbial translocation (Escherichia coli) was detected in the colon or ileum of infected or uninfected NPMs, which again differed to that observed in ChRMs. In conclusion, NPMs retained superior intestinal Integrity and limited microbial translocation during SIV infection, which may contribute to their lower immune activation compared with ChRMs.

关键词： Immune activation Intestinal Integrity Microbial translocation SIVmac239 Macaca leonina Northern pig-tailed macaques Macaca mulatta Chinese rhesus macaques

Estimation method of SBAS dual-frequency range error Integrity parameter

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Satellite Navigation 2020年第1期1卷 93-100页

作者： Bo Shao Qun Ding Xianbing Wu The 20th Research Institute of CETC Xi’an 710068ShaanxiChina

The development of a dual-frequency multi-constellation satellite-based augmentation system(DFMC SBAS)is in progress worldwide.The broadcasted dual-frequency range error(DFRE)Integrity parameter reflects the effects of satellite ephemeris and clock corrections.A user uses the DFRE to calculate the protection level and then determines whether the DFMC SBAS service satisfies the requirements of the current flight phase.However,the calculation of the DFRE has not been reported.Herein,a DFRE estimation method is proposed based on the projection method.Using the ephemeris-clock covariance matrix of each satellite,the maximal projection direction was solved,and the projection of the covariance matrix on this direction was used as the DFRE to form an envelope for the maximal corrected error.Results show that the DFRE can form an envelope of the maximal corrected error with a set probability,and the Integrity performance in the user segment satisfies the Category I precision approach requirement.

关键词： Satellite-based augmentation system Dual-frequency multi-constellation Dual-frequency range error Integrity

Assessment of structure Integrity, corrosion behavior and microstructure change of AZ31B stent in porcine coronary arteries

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Journal of Materials Science & Technology 2020年第4期39卷 39-47页

作者： Shanshan Chen Bin Zhang Bingchun Zhang Hao Lin Hui Yang Feng Zheng Ming Chen Ke Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Department of Cardiology of Peking University First Hospital Beijing 100034China

Magnesium alloy coronary stent becomes a hot research topic due to its biodegradable character for avoiding late thrombosis and late restenosis.However,fracture of Mg alloy stent was a common issue after implantation.In this study,18 drug-eluting biodegradable AZ31 B stents were implanted into porcine coronary arteries to assess its structural Integrity,corrosion behavior and microstructure change in vivo.The coronary artery tissue responses to AZ31 B stent implantation were detected by quantitative coronary angiography and optical coherence tomography at the set time periods.In addition,further analyses were focused on the stent structure Integrity,corrosion behaviors and the microstructure change of Mg alloy stents after implantation.A large number of fractures on stent struts were observed by high-resolution transmission X-ray tomography clearly.Moreover,degradation products,twins and grain refinement that appeared in Mg alloy stent matrix after implantation were also observed during the study.Inferred from this study,it is shown that the loss of AZ31 B stent structural Integrity may be the result of stress concentration,degradation and microstructure change.

关键词： AZ31B Coronary stent Structural Integrity Degradation Microstructure

SIV:A Structural Integrity Verification Approach of Cloud Components with Enhanced Privacy

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Tsinghua Science and Technology 2019年第5期24卷 557-574页

作者： Bo Zhao Peiru Fan Pengyuan Zhao Mingtao Ni Jinhui Liu School of Cyber Scienee and Engineering. Wuhan University Wuhan 430072 China. School of Computer Science Shaanxi Normal University Xi'an 710062 China

Private data leakage is a threat to current Integrity verification schemes of cloud components. To address this issue, this work proposes a privacy-enhancing Structural Integrity Verification (SIV) approach. It is made up of three processes: proof organization, proof transformation, and Integrity judgement. By introducing a Merkle tree technique, the Integrity of a constituent part of a cloud component on a node is represented by a root value. The value is then masked to cipher texts in proof transformation. With the masked proofs, a structural feature is extracted and validated in an Integrity judgement by a third-party verification provider. The Integrity of the cloud component is visually displayed in the output result matrix. If there are abnormities, the corrupted constituent parts can be located. Integrity is verified through the encrypted masked proofs. All raw proofs containing sensitive information stay on their original nodes, thus minimizing the attack surface of the proof data, and eliminating the risk of leaking private data at the source. Although some computations are added, the experimental results show that the time overhead is within acceptable bounds.

关键词： Integrity verification cloud components structural feature privacy

General aspects on structural Integrity

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Chinese Journal of Aeronautics 2019年第1期32卷 114-132页

作者： J.J.XIONG R.A.SHENOI School of Transportation Science and Engineering Beihang University Faculty of Engineering and Environment University of Southampton

This paper seeks to mark the fruitful collaborative research between scholars in the University of Southampton and Beihang University for last 25 years on structural Integrity. Their efforts addressed some important issues in structural Integrity such as fatigue and fracture behavior,fatigue load spectra, fatigue and fracture lifetimes, reliability-based service period, adhesively bonded composite patch repairs, Plain Woven Fabric(PWF) composites and composite artefacts.New advances in engineering approaches, experimental methods, numerical algorithms and understanding of failure mechanisms relating to structural Integrity are highlighted. Probable limits(or drawbacks) are also discussed. This review provides an insight into the general aspects on structural Integrity and constitutes a basis for pointers to the further works on structural Integrity.

关键词： Composites Fatigue Fracture Reliability Repair Structural Integrity

Cell-free DNA Integrity for the monitoring of breast cancer:Future perspectives?

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World Journal of Clinical Oncology 2018年第2期9卷 26-32页

作者： Navid Sobhani Daniele Generali Fabrizio Zanconati Marina Bortul Bruna Scaggiante Department of Medical Surgical and Health Sciences University of Trieste Cattinara Academic Hospital Department of Life Sciences University of Trieste

Breast cancer(BC) is the most common cancer and the second cause of death in women worldwide. Therapeutic options are increasing, but the response to treatments is not always efficient and the risk of recurrence covers decades. In this perspective, the need to have a proper follow-up for the therapeutic responses and for anticipating recurrence it is urgent in the clinical setting. Liquid biopsy provides the basic principle for a non-invasive method for the routinely monitoring of BC. However, due to the heterogeneity of tumors during onset and progression, the search for tumor DNA mutations of targeted genes in plasma/serum is a limiting factor. A possible approach overtaking this problem comes from the measurement of cell-free DNA Integrity, which is an independent factor from the mutational status and theoretically is representative of all tumors. This review summarizes the state-of-the-art of cell-free DNA Integrity researches in BC, the controversies and the future perspective.

关键词： cfDNA Integrity Liquid biopsy Breast cancer ALU sequences LINE-1 sequences

In the interests of science: Jointly promoting research Integrity is the cornerstone

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Nano Materials Science 2021年第4期3卷 319-320页

作者： Jingyuan Xue Weilang Wang Yongsong Yan Journals Department Chongqing UniversityChongqing400044PR China

1.Introduction We are all familiar with the word"Integrity"and have:some common understanding of it.It is generally accepted that honesty and reliability are two important aspects of Integrity.Specifc to scientific research,what is research Integrity?Why does it matter?Is it just the responsibility of researchers themselves or a shared responsibility of the entire research community?

关键词： corners Integrity themselves