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WAMS-based monitoring and control of Hopf bifurcations in multi-machine power systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第6期9卷 840-848页

作者： Shao-bu WANG Quan-yuan jiaNG Yi-jia cao School of Electrical Engineering Zhejiang University Hangzhou 310027 China

A method is proposed to monitor and control Hopf bifurcations in multi-machine power systems using the information from wide area measurement systems (WAMSs). The power method (PM) is adopted to compute the pair of conjugate eigenvalues with the algebraically largest real part and the corresponding eigenvectors of the Jacobian matrix of a power system. The distance between the current equilibrium point and the Hopf bifurcation set can be monitored dynamically by computing the pair of con- jugate eigenvalues. When the current equilibrium point is close to the Hopf bifurcation set, the approximate normal vector to the Hopf bifurcation set is computed and used as a direction to regulate control parameters to avoid a Hopf bifurcation in the power system described by differential algebraic equations (DAEs). The validity of the proposed method is demonstrated by regulating the reactive power loads in a 14-bus power system.

关键词： Wide area measurement system (WAMS) Hopf bifurcations Monitoring of bifurcations Control of bifurcations

Hydrolysis and Photolysis of Herbicide Clomazone in Aqueous Solutions and Natural Water Under Abiotic Conditions

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Journal of Integrative Agriculture 2013年第11期12卷 2074-2082页

作者： cao jia DIAO Xiao-ping HU Ji-ye School of Agriculture Hainan University School of Chemistry and Biological Engineering University of Science and Technology Beijing

The hydrolysis and photolysis of clomazone in aqueous solutions and natural water were assessed under natural and controlled conditions. Kinetics of hydrolysis and photolysis of clomazone were determined by HPLC-DAD. Photoproducts were identiifed by HPLC-MS. No noticeable hydrolysis occurred in aqueous buffer solutions （（25±2）°C, pH （4.5±0.1）, pH （7.4±0.1）, pH （9.0±0.1）;（50±2）°C, pH （4.5±0.1）, pH （7.4±0.1）） or in natural water up to 90 d. At pH （9.0±0.1） and （50±2）°C the half-life of clomazone was 50.2 d. Clomazone photodecomposition rate in aqueous solutions under UV radiation and natural sunlight followed ifrst-order kinetics. Degradation rates were faster under UV light （half-life of 51-59 min） compared to sunlight （half-life of 87-136 d）. Under UV light, four major photoproducts were detected and tentatively identiifed according to HPLC-MS spectral information such as 2-chlorobenzamide, N-hydroxy-（2-benzyl）-2-methylpropan-amide, 2-[2-phenol]-4,4-dimethyl-3-isoxazolidinone and 2-[（4,6-dihydroxyl-2-chlorine phenol）]-4,4-dimethyl-3-isoxazolidinone. These results suggested that clomazone photodegradation proceeds via several reaction pathways：1） dehalogenation;2） substitution of chlorine group by hydroxyl;3） cleavage of the side chain. Photosensitizers, such as H2O2 and ribolfavin, could enhance photolysis of clomazone in natural sunlight. In summary, we found that photoreaction is an important dissipation pathway of clomazone in natural water systems.

关键词： clomazone hydrolysis photolysis photoproducts abiotic

APPLICATION OF QUADRATIC AND CUBIC TURBULENCE MODELS ON CAVITATING FLOWS AROUND SUBMERGED OBJECTS

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Journal of Hydrodynamics 2012年第6期24卷 823-833页

作者： CHEN Ying LU Chuan-jing cao jia-yi CHEN Xin Department of Engineering Mechanics Shanghai Jiao Tong University Department of Engineering Mechanics and State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University

Quadratic and cubic Non-Linear Eddy-Viscosity Models （NLEVMs） at low Reynolds number （Re） correction were introduced into the present Computational Fluid Dynamics （CFD） framework, to provide better numerical treatment about the anisotropic turbulence stress in cavitating flows, which have large density ratio and large-scaled swirling flow structures. The applications of these NLEVMs were carried out through a self-developed cavitation code, coupled with a cavitation model based on the transport equation of liquid phase. These NLEVMs were firstly validated by the benchmark of disk supercavity, and found able to obtain more accurate capture of the hydrodynamic properties than the linear models. One of such models was further applied on the cavitation problem of submerged vehicles. Ultimately, the supercavitating flows around an especially designed underwater vehicle were predicted using the cubic k - e turbulence model, and its cavitation behaviors were studied.

关键词： cavitating flow Non-Linear Eddy-Viscosity Model (NLEVM) submerged object cavitation model

Forward and backward models for fault diagnosis based on parallel genetic algorithms

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1420-1425页

作者： Yi LIU Ying LI Yi-jia cao Chuang-xin GUO School of Electrical Engineering Zhejiang University Hangzhou 310027 China

In this paper, a mathematical model consisting of forward and backward models is built on parallel genetic algorithms (PGAs) for fault diagnosis in a transmission power system. A new method to reduce the scale of fault sections is developed in the forward model and the message passing interface (MPI) approach is chosen to parallel the genetic algorithms by global sin-gle-population master-slave method (GPGAs). The proposed approach is applied to a sample system consisting of 28 sections, 84 protective relays and 40 circuit breakers. Simulation results show that the new model based on GPGAs can achieve very fast computation in online applications of large-scale power systems.

关键词： Forward and backward models Fault diagnosis Global single-population master-slave genetic algorithms (GPGAs) Parallel computation

Ultrasonography of sclerosing angiomatoid nodular transformation in the spleen

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World Journal of Gastroenterology 2010年第29期16卷 3727-3730页

作者： jia-Ying cao Hui Zhang Wen-Ping Wang Department of Ultrasound Zhongshan Hospital Fudan University Shanghai 200032China

We report three rare cases of sclerosing angiomatoid nodular transformation(SANT) in the *** compared the conventional and contrast-enhanced ultrasonographic *** conventional sonographic examinations exhibited solitary lesions without common respects,while contrast-enhanced ultrasonography(CEUS) revealed nodular appearance mimicking its pathologic *** suggests that CEUS can provide morphologic information for diagnosing SANT.

关键词： Sclerosing angiomatoid nodular transformation Contrast-enhanced ultrasonography Ultrasound

Wall sheeting diagnosis in fluidized beds based on chaos analysis of acoustic emission signals

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第9期10卷 1341-1349页

作者： Yi-jia cao Jing-dai WANG Wei LIU Yong-rong YANG State Key Laboratory of Chemical Engineering Zhejiang University Hangzhou 310027 China Department of Chemical and Biochemical Engineering Zhejiang University Hangzhou 310027 China

A novel method, based on acoustic emission (AE) techniques, for detecting agglomeration in fluidized beds is presented. Particle size characteristics are determined based on the principle that AE signals with different frequency band energies are emitted when particles of different sizes impact an internal wall. By applying chaotic analysis to the AE signals, the malfunction coefficients are well defined. Agglomeration in the fluidized bed can then be detected by the sudden variation of malfunction coefficients. AE signals were investigated in a laboratory scale heated fluidized bed and an industrial polyethylene fluidized bed. Experimental data showed that the malfunction coefficients increased with the growth of agglomeration. The results indicated that agglomeration in fluidized beds can be predicted and diagnosed effectively and precisely using AE techniques based on chaotic analysis.

关键词： Acoustic emission (AE) Fluidized bed Malfunction coefficient Agglomeration Chaos

Successful treatment of solitary bladder plasmacytoma:A case report

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World Journal of Clinical Cases 2021年第25期9卷 7453-7458页

作者： jia-Dong cao Peng-Hui Lin Dan-Feng Cai jia-Hua Liang Department of Urology The Second Affiliated Hospital of Guangzhou University of Chinese MedicineGuangzhou 510105Guangdong ProvinceChina The Second Clinical College Guangzhou University of Chinese MedicineGuangzhou 510405Guangdong ProvinceChina

BACKGROUND Plasmacytoma is a rare neoplastic disorder that arises from *** bladder plasmacytoma,a type of solitary extramedullary plasmacytoma,is even *** for solitary extramedullary plasmacytoma include surgery,chemotherapy,and ***,there are no clinical trials or guidelines specifying which treatment might represent the gold *** SUMMARY We herein report a case of a 51-year-old woman with solitary bladder plasmacytoma(SBP).There remains no consensus regarding the optimal treatment for ***,we successfully treated her with transurethral resection of bladder tumor followed by postoperative radiotherapy(50 Gy/25 F).The patient remained free of tumor recurrence at a 7-mo *** Radiation is the potential main treatment for ***,surgery is also necessary.

关键词： Bone marrow Local neoplasm recurrence Multiple myeloma M-proteins Urinary bladder neoplasms Case report

Optimal power flow calculation in AC/DC hybrid power system based on adaptive simplified human learning optimization algorithm

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Journal of Modern Power Systems and Clean Energy 2016年第4期4卷 690-701页

作者： jia cao Zheng YAN Xiaoyuan XU Guangyu HE Shaowei HUANG The Ministry of Education Key Laboratory of Control of Power Transmission and Conversion Department of Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

This paper employs an efficacious analytical tool,adaptive simplified human learning optimization(ASHLO)algorithm,to solve optimal power flow(OPF)problem in AC/DC hybrid power system,considering valve-point loading effects of generators,carbon tax,and prohibited operating zones of generators,*** algorithm,involves random learning operator,individual learning operator,social learning operator and adaptive *** compare and analyze the computation performance of the ASHLO method,the proposed ASHLO method and other heuristic intelligent optimization methods are employed to solve OPF problem on the modified IEEE 30-bus and 118-bus AC/DC hybrid test *** results indicate that the ASHLO method has good convergent property and ***,the impacts of wind speeds and locations of HVDC transmission line integrated into the AC network on the OPF results are systematically analyzed.

关键词： Adaptive simplified human learning optimization algorithm Optimal power flow AC/DC hybrid power system Valve-point loading effects of generators Carbon tax Prohibited operating zones

The final collision of the caoB:Constraint from the zircon U-Pb dating of the Linxi Formation,Inner Mongolia

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Geoscience Frontiers 2015年第2期6卷 211-225页

作者： Jie Han jian-Bo Zhou Bin Wang jia-Lin cao College of Earth Sciences Jilin University School of Resources and Materials Northeastern University at Qinghuangdao

The Linxi Formation occupies an extensive area in the eastern Inner Mongolia in the Central Asian Orogenic Belt （caoB）. The Linxi Formation is composed of slate, siltstone, sandstone and plant, lamellibranch microfossils in the associated strata. Major and trace element data （including REE） for sandstones from the formation indicate that these rocks have a greywacke protolith and have been deposited during a strong tectonic activity. LA-ICPMS U-Pb dating of detrital zircons yield ages of 1801 to 238 Ma for four samples from the Linxi Formation. 425-585 Ma, together with the ~500 Ma age for the metamorphism event previously determined for Northeast China, indicates that their provenance is the metamorphic rocks of Pan-African age that have a tectonic affinity to NE China. A few older zircons with U-Pb ages at 1689-1801 Ma, 1307 1414 Ma, 593-978 Ma are also present, revealing the Neoproterozoic history of NE China. The youngest population shows a peak at ca. 252 Ma, suggesting that the main deposition of the Linxi Formation was at late Permain. Moreover, the ca. 250 Ma zircon grains of all four samples yield weighted mean ^206pb/^238U ages of 250 ± 3 Ma, 248 ± 3 Ma, 249 ± 3 Ma, and 250 ± 2 Ma, respectively. These ages, together with the youngest zircon age in the sample ZJB-28 （ca. 238 Ma）, suggest that the deposition of the Linxi Formation extended to the early Triassic. Combining with previous results, we suggest that the final collision of the Central Asian Orogenic Belt （caoB） in the southern of Linxi Formation, which located in the Solonker-Xra Moron-Changchun suture, and the timing for final collision should be at early Triassic.

关键词： Linxi formation LA-ICPMS U-Pb dating Solonker Xra Moron Changchun suture Final collision timing Early Triassic Central Asian Orogenic Belt