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Fault detection based on H_∞ states observer for networked control systems

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Journal of Systems Engineering and Electronics 2009年第2期20卷 379-387页

作者： zhu Zhangqing Jiao xiaocheng Dept. of Control and System Engineering Nanjing Univ. Nanjing 210093 P. R. China

The influence of random short time-delay to networked control systems （NCS） is changed into an unknown bounded uncertain part. Without changing the structure of the system, an Hoo states observer is designed for NCS with short time-delay. Based on the designed states observer, a robust fault detection approach is proposed for NCS. In addition, an optimization method for the selection of the detection threshold is introduced for better tradeoff between the robustness and the sensitivity. Finally, some simulation results demonstrate that the presented states observer is robust and the fault detection for NCS is effective.

关键词： networked control systems fault detection states observers time-delays robustness

High-precision magnetic field measurement system based on a coherent population trapping magnetometer onboard the SATech-01 satellite

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Science China(Technological Sciences) 2025年第2期68卷 227-242页

作者： Hongbo XUE Wei SONG Haoran ZHAO Yiteng ZHANG Shanzhi YE Jindong WANG Ran TAO Peng SANG Keli CHEN Xingzi BI Bingjun CHENG Bin ZHOU Yongliang XUE Yingying TANG Liu LIU Jinsong LI xiaocheng zhu Baoquan LI Jinguo LIU Wen CHEN Xiaofeng ZHANG Yonghe ZHANG Lei LI State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Key Laboratory of Electronics and Information Technology for Space Systems National Space Science CenterChinese Academy of SciencesBeijing 100190China State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang 110016China Innovation Academy for Microsatellites Chinese Academy of SciencesShanghai 201304China

On July 27,2022,a high-precision system for measuring the magnetic field based on a coherent population trapping magnetometer(referred to as the CPT system)was launched onboard the Space Advanced Technology demonstration satellite(SATech-01)by a ZK-1A *** payload comprises a scalar coherent population trapping magnetometer(CPTM),triaxial anisotropic magnetoresistance magnetometer(AMRM),and nano star tracker mounted on a non-magnetic telescopic tubular *** configuration enables synchronized measurement of scalar and vector geomagnetic fields,as well as the attitude,making the payload with its compact sensors suitable for applications on miniature satellite *** November 7,2022,the novel telescopic tubular mast was deployed in orbit,extending to a length of 5.28 *** CPTM,an absolute scalar magnetometer with an omnidirectional sensor,is the first China-developed quantum/atomic magnetometer successfully operating in *** orbit,the CPTM has sensitivity of~10 pT/Hz^(1/2) and can automatically operate under complex magnetic field *** difference between the scalar fields obtained using the CPTM and CHAOS model has a mean deviation of -3.73 nT and a standard deviation of 26.11 nT(1σ),without on-orbit calibration or *** miniaturized AMRM has a sensitivity of~0.3 nT/Hz^(1/2) and maintains stable and reliable operation in *** low-power and miniaturized nano star tracker has a measurement uncertainty of 14.23″(1σ)in *** mission has realized the on-orbit technical verification of the integrated and synchronized detection of the vector magnetic field and attitude and fully validated the system’s performance,automation level,and reliability.

关键词： magnetic field measurement system coherent population trapping magnetometer anisotropic magnetoresistance magnetometer nano star tracker non-magnetic telescopic tubular mast satellite

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A Confined Laminar Slot Impinging Jet at Low Reynolds Numbers:Unsteady Flow and Heat Transfer Characteristics

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Journal of Thermal Science 2023年第2期32卷 753-769页

作者： SHI Lei SUN Chong zhu xiaocheng DU Zhaohui School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In this study,the unsteady flow and heat transfer characteristics of a laminar slot jet at low Reynolds numbers impinging on an isothermal plate surface in a two-dimensional confined space are numerically *** investigations are performed at Reynolds numbers of 120,150 and 200 based on the nozzle width and mean inlet velocity of the *** show that the Reynolds numbers of 120,150 and 200 correspond to different flow features,namely,a steady flow,an intermittent flapping motion of jet column and a continuous sinusoidal flapping state,*** on some time snapshots of the flow field,the dynamic characteristics and driving mechanism of the intermittent flapping motion of the jet column and the continuous sinusoidal flapping state are *** the jet flaps at the Reynolds number 150 and 200,there are other Nusselt number peaks outside the stagnation zone,which are related to the interference between the vortices shedding on both sides of the jet and the boundary layers of the plate ***,the dynamic mode decomposition is implemented to accurately extract flow modes with characteristic *** a Reynolds number of 150,there is a flapping mode,which describes the lateral flapping motion of the jet *** the Reynolds number is 200,there are multiple modes related to the flapping motion of the jet,as well as a low-frequency mode,which reflects the periodic changes of the boundary contour and position of the recirculation zone.

关键词： laminar slot impinging jet unsteady flow heat transfer Nusselt number dynamic mode decomposition

EXPERIMENTAL INVESTIGATION FOR THE EFFECT OF ROTATION ON THREE-DIMENSIONAL FLOW FIELD IN FILM-COOLED TURBINE

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Chinese Journal of Mechanical Engineering 2007年第1期20卷 10-15页

作者： YUAN Feng zhu xiaocheng DU Zhaohui School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

An experimental investigation of three-dimensional flow field in a film-cooled turbine model is carried out by using particle image velocimeter （PIV） in a low-speed wind tunnel. The effects of different blowing ratios （M=1.5, 2） on the flow field are studied. The experimental results reveal the classical phenomena of the formation of kidney vortex pair and secondary flow in wake region behind the jet hole. And the changes of the kidney vortex pair and the wake at different locations away from the hole on the suction and pressure sides are also studied. Compared with the flow field in stationary cascade, there are centrifugal force and Coriolis force existing in the flow field of rotating turbine, and these forces bring the radial velocity in the jet flow. The effect of rotatien on the flow field of the pressure side is more distinct than that on the suction side from the measured flow fields in Y-Z plane and radial velocity contours. The increase of blowing ratio makes the kidney vortex pair and the secondary flow in the wake region stronger and makes the range of the wake region enlarged.

关键词： Film-cooled turbine rotor PIV measurement Blowing ratio Three-dimensional flow field

EXPERIMENTAL INVESTIGATION OF TIP CLEARANCE FLOW FOR AN AXIAL FLOW FAN ROTOR

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Chinese Journal of Mechanical Engineering 2006年第3期19卷 376-382页

作者： GUO Qiang zhu xiaocheng DU Zhaohui School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

The flow field in the tip region of an axial ventilation fan is investigated with a particle image velocimeter （PIV） system at the design condition. Flow fields with three different tip clearances are surveyed on three different circumferential planes, respectively. The phase-locked average method is used to investigate the generation and the development of a tip leakage vortex. The result from PIV system is compared with that from a particle dynamics anemometer（PDA） system. Both data are in good agreement and the structure of the tip leakage vortex for the rotor is illustrated. The characteristic of a leakage vortex is described in both velocity vectors and vortical contours. The unsteadiness of the leakage vortex and the position of the vortex are surveyed in detail, which interprets the discrepancy between the numerical simulation and PDA experimental results to a certain extent. The center loci of tip leakage vortex at different times and the mean center loci of the leakage vortex are displayed particularly. Finally, the trajectories of the tip leakage vortex by the experimental measurement are compared with predictions from the existing models for high speed and high-pressure compressors and turbines when appropriately interpreted. A good agreement is obtained.

关键词： Axial ventilation fan Tip leakage vortex Particle image velocimetry (PIV) Vortex center trajectory

Receptivity and structural sensitivity study of the wide vaneless diffuser flow with adjoint method

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Chinese Journal of Aeronautics 2018年第8期31卷 1679-1690页

作者： xiaocheng zhu Chenxing HU Zezhao LIU Hao LIU Zhaohui DU School of Mechanical Engineering/2011 Aero-Engine Collaborative Innovation Center Shanghai Jiao Tong University College of Politics and Law Hebei University

The stability of the flow in the vaneless diffuser of a centrifugal compressor is studied with the linear theory. The characteristics of direct and adjoint perturbation modes are investigated,and the receptivity of the instability mode to momentum forcing or mass injection is identified based on the adjoint modes. Analysis shows that the perturbation with the largest amplitude is located at the outlet of the vaneless diffuser, while the highest-receptivity region is located in the middle of the vaneless diffuser along the radial direction. The large difference between the direct and adjoint modes indicates that the instability mechanism cannot be identified from a study of either eigenmode separately. Therefore, the structural sensitivity analysis is adopted to study the feedback of the instability mode. The structural sensitivity of the eigenvalue which is proportional to the perturbation pressure and velocity is used to explain the mechanism of flow control for the vaneless diffuser.

关键词： Adjoint method Receptivity Rotating stall Structural sensitivity Vaneless diffuser

EXPERIMENTAL INVESTIGATION OF ROTATING STALL FOR A LOW-SPEED CENTRIFUGAL COMPRESSOR

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Chinese Journal of Mechanical Engineering 2008年第3期21卷 76-83页

作者： zhu xiaocheng GUO Qiang DU Zhaohui CHEN Hua ZHAO Yan School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China Honeywell Corporation Shanghai 200030 China

Unsteady flows and rotating stall of a low-speed centrifugal compressor are investigated by measuring vaneless diffuser wall static pressure fluctuation and internal flow fields at different small flow fluxes. During the experiment, firstly the real time static pressure fluctuations on the vaneless diffuser shroud at different circumferential and radial position were acquired by high-frequency dynamic pressure transducers. Discrete Fourier transformation analysis and cross-correlation analysis were applied to the experimental results to ascertain the rotating stall beginning operation conditions and stall cells numbers and rotating speed. Secondly, the vaneless diffuser inlet flow angle distribution along diffuser width direction was acquired by single hotwire, which was compared with SENOO＇s analysis results. At last, the internal flow fields of the centrifugal compressor were investigated with a particle image velocimetry （PIV） system at different small flow fluxes. The flow field development of vaneless diffuser and blade flow passage are given at rotating stall conditions. The experiments enrich the understanding of rotating stall flow phenomenon of the low-speed centrifugal compressor and provide full experiment data for designing high performance centrifugal compressor.

关键词： Rotating stall Centrifugal compressor Vaneless diffuser Particle image velocimetry (PIV)

Effect of Decanoic Acid on the Cognitive Function of AD Mice

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Medicinal Plant 2017年第4期8卷 48-51页

作者： Zheng LI xiaocheng zhu Xiaoqun DUAN Guilin Medical University Department of Neurology Ganzhou Municipal Hospital

[Objectives] To study the effect of PPARγ agonist DA on the cognitive function of AD mice as well as the mechanism.[Methods]50 Kunming male mice were randomly divided into normal control group,model group and decanoic acid administration group,the AD mice model was established by subcutaneous injection of D-galactose for 8 weeks,and the treatment group was administered orally with different doses of decanoic acid( low dose of 50 mg/kg,middle dose of 100 mg/kg,high dose of 200 mg/kg). After 8 weeks,the Morris water maze was used to detect the learning and memory capability of mice; HE staining was used to observe the morphological change of hippocampal cells in brain tissue; Western-blot and immunohistochemistry technique were used to detect the expression of PPARγ and Aβ42 protein in brain tissue; the ELISA method was used for the determination of TNF-α and i NOS level in serum. [Results]Morris water maze results showed that DA could significantly improve the learning and memory function in AD mice( P < 0. 05); HE staining showed that DA could significantly reduce degeneration in hippocampal cells; Western-blot and immunohistochemistry results showed that DA could promote the expression of PPARγ and reduce the expression of Aβ42 in brain tissue( P < 0. 05); ELISA results showed that the TNF-α,i NOS levels decreased in AD mice serum after DA treatment( P < 0. 05). [Conclusions] DA could significantly improve the cognitive function of AD mice,improve the degeneration of hippocampal cells in brain tissue,and decrease the expression of Aβ42 in brain tissue. The mechanism might be related to activation of PPARγ protein and down-regulation of expression of relevant inflammatory factors.

关键词： Decanoic acid Alzheimer’s disease PPARγ D-galactose

Outcome of bariatric surgery in patients with unexpected liver cirrhosis: A multicenter study from China

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Liver Research 2024年第3期8卷 172-178页

作者： Xia Sun Libin Yao Xing Kang Weihua Yu Fidele Kakule Kitaghenda Mohammad Sajjad Ibn Rashid Angeline Nogue Taguemkam Jian Hong Zhiyong Dong Xitai Sun xiaocheng zhu Department of Gastrointestinal Surgery The Affiliated Hospital of Xuzhou Medical UniversityXuzhouJiangsuChina Department of Pancreatic and Metabolic Surgery Nanjing Drum Tower HospitalAffiliated Hospital of Medical SchoolNanjing UniversityNanjingJiangsuChina Department of General Surgery Sir Run Run Shaw HospitalZhejiang University School of MedicineHangzhouZhejiangChina Department of Metabolic and Bariatric Surgery The First Affiliated Hospital of Jinan UniversityGuangzhouGuangdongChina

Background and aims Liver cirrhosis is a complex disease that may result in increased morbidity and mortality following bariatric surgery(BS).This study aimed to explore the outcome of BS in patients with unexpected cirrhosis,focusing on postoperative complications and the progression of liver *** A retrospective study of bariatric patients with cirrhosis from four centers in China between 2016 and 2023 was conducted,with follow-up for one year after *** primary outcome was the safety of BS in patients with unexpected cirrhosis,while the secondary outcome was the metabolic efficacy of BS in this group *** A total of 47 patients met the study criteria,including 46 cases of Child-Pugh class A cirrhosis and 1 case of Child-Pugh *** examination confirmed nodular cirrhosis in 21 patients(44.68%),pseudolobule formation in 1 patient(2.13%),lipedema degeneration with inflammatory cell infiltration in 3 patients(6.38%),and chronic hepatitis in 1 patient(2.13%).The average percentage of total weight loss was 29.73±6.53%at one year *** the 30-day postoperative period,the complication rate was 6.38%,which included portal vein thrombosis,gastrointestinal bleeding,and intra-abdominal ***,no cases of liver decompensation or mortality were reported during the follow-up *** remission rates of comorbidities among 41 patients one year after surgery were as follows:dyslipidemia 100%,type 2 diabetes 82.61%,hypertension 84.62%,and obstructive sleep apnea syndrome 85.71%.Conclusions BS can be safely performed in patients with unexpected cirrhosis in the compensated stage of liver disease,with low postoperative morbidity and no mortality observed during one-year follow-up.

关键词： Bariatric surgery(BS) Metabolic surgery Liver cirrhosis Obesity Type 2 diabetes mellitus(T2M)