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Large-eddy simulation and linear acoustic modeling of entropy mode oscillations in a model combustor with coolant injection

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Chinese Journal of Aeronautics 2018年第8期31卷 1691-1702页

作者： man zhang An LIANG AECC Commercial Aireraft Engine Co. LTD Shanghai 200241 China

Lean-burn combustor is particularly susceptible to combustion instability and the unsteady heat release is usually considered as the excitation of the self-maintained thermoacoustic oscillations. The transverse coolant injection is widely used to reduce the temperature of burnt gas, but on the other hand, it will introduce temperature fluctuation inside the ***, it is necessary to consider the influence of the coolant injection on combustion instability, and evaluate its dynamic feature. In this paper, Large-Eddy Simulation（LES） of the self-excited pressure oscillations in a model combustor with coolant injection is carried out. The analysis of transient flow characteristics and the identification of the pressure modes confirm that one of the low frequency pressure oscillations is related to entropy fluctuations, which is known as rumble combustion instability. The LES results show that transient coolant injection is another excitation of temperature fluctuation other than unsteady combustion. The amplitude of the entropy mode oscillation increases with increasing coolant air mass whereas the change of its frequency is insignificant. According to the major feature of entropy wave oscillation caused by coolant injection, a compact coolant injection model is proposed and applied in the One Dimensional（1 D） Acoustic Network Method（ANM）. Key correlations used in the model match well with LES data in low frequency range. This means that the coolant injection model is a complex one reflecting the interaction of the fluctuating coolant mass, pressure and temperature. Finally, the combustion instability frequencies and modes predicted by acoustic network method are also in good agreement with LES results.

关键词： Acoustic wave Combustion instabilityCoolant injection Entropy LES Network method Rumble Self-excited

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The secondary periodic element ■ and its applications

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Science China Mathematics 2025年第1期 207-222页

作者： Jianguo Hong Xiangjun Wang yu zhang Science College Shijiazhuang University School of Mathematical Sciences Nankai University Center for Applied Mathematics Tianjin University

Let p≥7 be a *** prove that ■ survives to E∞in the Adams-Novikov spectral ***,using the Thom map Φ:■,we can see that h0h3also survives to E∞in the classical Adams spectral *** an application of these results,we ...

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Controllable nucleation and deformation of skyrmions on surface of magnetic nanotubular monolayer

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Rare Metals 2024年第7期43卷 3250-3259页

作者： Xin-Xin zhang Chen-yu zhang Yi-Xin Xing Chao man Jiao Liu Yong Hu Department of Physics College of SciencesNortheastern UniversityShenyang 110819China School of Materials and Mineral Resources Engineering Universiti Sains MalaysiaEngineering Campus14300 Nibong TebalPenangMalaysia State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

Magnetic skyrmions emerge when the energy of ferromagnetic exchange interaction promoting parallel alignment of spins enters in competition with energies favoring non-collinear alignment of spins such as Dzy aloshinskii-Moriya interaction(DMI),long-rang dipole-dipole interaction(DDI),or higher-order exchange *** perform an unbiased Monte Carlo simulation to study the DMI-based skyrmion nucleation and stabilization on the surface of magnetic nanotubular monolayer controlled by tuning constants of DDI(g) and next-nearest-neighbor antiferromagnetic exchange interaction(j') with appropriate *** g and j',the loosely distributed skyrmions initially nucleate on the surface of nanotube approaching to the magnetic field(h) direction with increasing h in the intermediate ***,the skyrmion size,shape,density,distribution and crystal structure,as well as its driven field range,are tailored by g and j'.This work demonstrates the skyrmion nucleation mechanisms in three-dimensional magnetic nanostructures with curvature effect and multiple interactions,serving as a benchmark for a guide to experimentalists for preparation of samples in magnetic skyrmion states.

关键词： Magnetic nanotube Magnetic skyrmion Dzyaloshinskii-Moriya interaction Dipole-dipole interaction Monte Carlo simulation

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Strategies for adaptation to high light in plants

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aBIOTECH 2024年第3期5卷 381-393页

作者： man zhang yu Ming Hong-Bin Wang Hong-Lei Jin State Key Laboratory of Traditional Chinese Medicine/School of Pharmaceutical Sciences Guangzhou University of Chinese MedicineGuangzhou 510006China Institute of Medical Plant Physiology and Ecology Guangzhou University of Chinese MedicineGuangzhou 510006China Key Laboratory of Chinese Medicinal Resource From Lingnan(Guangzhou University of Chinese Medicine) Ministry of EducationGuangzhou 510006China Guangzhou Key Laboratory of Chinese Medicine Research on Prevention and Treatment of Osteoporosis The Third Affiliated Hospital of Guangzhou University of Chinese MedicineGuangzhou 510375China

Plants absorb light energy for photosynthesis via photosystem complexes in their ***,excess light can damage the photosystems and decrease photosynthetic output,thereby inhibiting plant growth and *** have developed a series of light acclimation strategies that allow them to withstand high *** the first line of defense against excess light,leaves and chloroplasts move away from the light and the plant accumulates compounds that filter and reflect the *** the second line of defense,known as photoprotection,plants dissipate excess light energy through non-photochemical quenching,cyclic electron transport,photorespiration,and scavenging of excess reactive oxygen *** the third line of defense,which occurs after photodamage,plants initiate a cycle of photosystem(mainly photosystem II)*** addition to being the site of photosynthesis,chloroplasts sense stress,especially light stress,and transduce the stress signal to the nucleus,where it modulates the expression of genes involved in the stress *** this review,we discuss current progress in our understanding of the strategies and mechanisms employed by plants to withstand high light at the whole-plant,cellular,physiological,and molecular levels across the three lines of defense.

关键词： Defense Photoprotection Photosystem Repair of PSII

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Coal and rock dynamic disaster prevention and control technology in the large mining face of a deep outburst mine

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Frontiers of Earth Science 2023年第3期17卷 701-712页

作者： Jianguo zhang man WANG Hongwei ZHOU Dongming zhang Beichen yu Chongyang WANG yujie WANG State Key Laboratory of Coking Coal Exploitation and Comprehensive Utilization China Pingmei Shenma Holding Group CO.LTDPingdingshan 467000China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China School of Resources and Safety Engineering Chongqing UniversityChongqing 400030China School of Energy and Mining Engineering China University of Mining and Technology(Beijing)Beijing 100083China

In this study, we systematically studied the occurrence regularity of in situ stress in the Pingdingshan mine. The critical criterion model of coal-rock destabilization was established based on the theoretical framework of fracture mechanics. Furthermore, we analyzed the coupling destabilization mechanism of in situ stress and gas and studied the influence of the variation between original rock stress and mining-induced stress on the critical criterion. Through field experiments and applications, we established a three-dimensional gas drainage technology system for areas with a large mining height and long work face. Based on our research, a demonstration project was developed for deep mine dynamic disaster control. The technical system included the arrangement and optimization of pre-drainage holes along the coal seam, technology, and optimization of gas drainage through the bottom drainage tunnel and upper corner, gas drainage technology through sieve tubes, and a two plugging with one injection under pressure sealing technology. The implementation of the demonstration project effectively reduced the gas content and pressure of the coal seam in the deep mine, and the project increased the critical strength of the instability and failure of coal and rock.

关键词： in-situ stress dynamic disaster critical criterion gas drainage

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Adaptive control of nonlinear systems with severe uncertainties in the input powers

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Science China(Information Sciences) 2021年第1期64卷 227-238页

作者： Linzhen yu yungang LIU Yongchao man School of Control Science and Engineering Shandong University

In this study, we discuss global adaptive stabilization for a class of uncertain nonlinear *** input powers of the system are unknown, and the upper bound and the nonzero lower bound are not known in advance. This suggests that the system suffers from severe uncertainties with respect to the input powers when compared with the related literature, which would considerably challenge the control design. The switching-based strategy can compensate for severe system uncertainties, especially new types of uncertainties, including those associated with the input powers. Herein, a switching adaptive controller is successfully designed to ensure that the resulting closed-loop system states are globally bounded and ultimately converge to the origin(the equilibrium point). The proposed controller is extended to the systems with unknown control directions by redefining the involved switching sequences. A simulation example demonstrates the effectiveness of the proposed switching adaptive controller.

关键词： nonlinear systems severe uncertainties global stabilization unknown input powers switching adaptive control

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Direct measurement of the concurrence of hybrid entangled state based on parity check measurements

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Chinese Physics B 2019年第1期28卷 205-209页

作者： man zhang Lan Zhou Wei Zhong yu-Bo Sheng Institute of Quantum Information and Technology Nanjing University of Posts and TelecommunicationsNanjing 210003China School of Science Nanjing University of Posts and TelecommunicationsNanjing 210003China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology(Ministry of Education) Nanjing University of Posts and TelecommunicationsNanjing 210003China

The hybrid entangled state is widely discussed in quantum information processing. In this paper, we propose the first protocol to directly measure the concurrence of the hybrid entangled state. To complete the measurement, we design parity check measurements(PCMs) for both the single polarization qubit and the coherent state. In this protocol, we perform three rounds of PCMs. The results show that we can convert the concurrence into the success probability of picking up the correct states from the initial entangled states. This protocol only uses polarization beam splitters, beam splitters, and weak cross-Kerr nonlinearities, which is feasible for future experiments. This protocol may be useful in future quantum information processing.

关键词： hybrid entangled state quantum computation parity measurement concurrence

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Evaluating the historical,clinical,and cultural value of the Tian Hui Yi Jian

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Journal of Traditional Chinese Medicine 2024年第1期44卷 220-221页

作者： yu Linyong GU man China Academy of Chinese Medical Sciences Beijing 100700China Institute for History of Medicine and Medical Literature China Academy of Chinese Medical SciencesBeijing 100700China

Tian Hui Yi Jian was compiled by the Tianhui Medical manuscripts Compilation Group,which includes scholars from the Institute for History of Medicine and Medical Literature of the China Academy of Chinese Medical Sciences(CACMS),Chengdu University of Traditional Chinese Medicine,Chengdu Institute of Cultural Relics and Archaeology,and Jingzhou Cultural Relics Protection *** was published by the Cultural Relics Press in November *** volume includes images of eight medical manuscripts,along with the Team's annotations,and photographs of a lacquered figurine with meridian-channels and words on its surface.

关键词： surface Chengdu Tian

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Three-segment control theory of MgO/Al2O3 ratio based on viscosity experiments and phase diagram analyses at 1500℃

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Journal of Iron and Steel Research International 2020年第6期27卷 624-630页

作者： Xin Jiang Huai-yu zhang Hai-yan Zheng Qiang-jian Gao Feng-man Shen School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

In recent years, more and more high Al2O3 iron ores were used in East Asia, especially in China, which increased the Al2O3 content in blast furnace (BF) slag and resulted in poor metallurgical properties of slag. Adding MgO-bearing flux is one of the methods to improve the metallurgical properties of slag with high Al2O3. However, there is lack of theoretical basis for the proper MgO/Al2O3 ratio. Therefore, the properties of slag in SiO2-CaO-MgO-Al2O3 system were investigated based on viscosity experiments and phase diagram analyses at 1500℃, and the proper MgO/Al2O3 ratio was explored according to the Al2O3 content in slag. The experimental results show that: (1) in the case of Al2O3 content less than 14mass%, there is no limitation of the MgO/Al2O3 ratio, and the amount of MgO in slag can be determined according to the hearth tempera-ture and desulfurization;(2) in the case of Al2O3 content between 15 and 17mass%, the proper MgO/Al2O3 ratio should be 0.40-0.50;(3) in the case of Al2O3 content between 18 and 20mass%, the proper MgO/Al2O3 ratio should be 0.45-0.55. Consequently, the three-segment control theory of MgO/Al2O3 for BF slag was built, and the actual BF performances proved the validity and applicability of this theory. The research contents and results can give theoretical guidelines for stable BF operation in a wide range of Al2O3 content of 12-20mass%.

关键词： MgO/Al2O3 ratio Blast furnace slag Viscosity Ironmaking Phase diagram

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Optimizing mechanical properties of HIPS fabricated with low-cost desktop 3D printers:investigating the impact of process parameters

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Advances in manufacturing 2024年第2期12卷 379-395页

作者： Jin-Ting Xu Guang-Wei zhang man-man Chen School of Automotive Engineering Dalian University of TechnologyDalian116024People’s Republic of China

Recently,low-cost desktop three-dimensional(3D)printers,employing the fused deposition modeling(FDM)technique,have gained widespread ***,most users cannot test the strength of printed parts,and little information is available about the mechanical properties of printed high-impact polystyrene(HIPS)parts using desktop 3D *** this study,the user-adjustable parameters of desktop 3D printers,such as crisscross raster orientation,layer thickness,and infill density,were *** experimental plans were designed using the Box-Behnken method,and tensile,3-point bending,and compression tests were carried out to determine the mechanical responses of the printed *** prediction models of the process parameters were regressed to produce the optimal combination of process *** experimental results showcase that the crisscross raster orientation has significant effects on the flexural and compression strengths,but not on the tensile *** an increase in the layer thickness,the tensile,flexural,and compression strengths first decreased and then increased,reaching their minimum values at approximately 0.16 mm layer *** addition,they all increased with an increase of infill *** was demonstrated that when the raster orientation,layer thickness,and infill density were 13.08°/–76.92°,0.09 mm,and 80%,respectively,the comprehensive mechanical properties of the printed HIPS were *** results can help end-users of desktop 3D printers understand the effects of process parameters on the mechanical properties,and offer practical suggestions for setting proper printing parameters for fabricating HIPS parts.

关键词： Desktop three-dimensional(3D)printers Fused deposition modeling(FDM) High-impact polystyrene(HIPS) Process parameters

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