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| 1 | Effects of annealing and firing in wet hydrogen on the dielectric breakdown strengths of alumina ceramics显示文摘Annealing and firing in wet hydrogen are widely used steps in the processing alumina.ceramic insulators that may affect their dielectric breakdown strengths(DBS).In this study,the effects of annealing(at 1300℃for 7 h)and firing in wet hydrogen on the DBS of alumina ceramics(all sintered at 1650℃)were studied,and the underlying mechanisms were analyzed by material characterizations.Annealing reduced the DBS of the 95%alumina ceramics due to the inter-granular phase crystallization,and the reduction in the DBS could be correlated to the reduction in mechanical strength.In contrast,annealing improved the DBS of the 99%alumina ceramic without intergranular phase transformation.Firing in wet hydrogen at 1500℃caused the DBS increment,which can be ascribed to the reduction in the concentrations of point defects and electrical carriers. | Jishi DU Binghua TANG Wei LIU Tao ZhANG Jiagen PENG Hu CHEN Yangjun LEI | 2020 | Journal of Advanced Ceramics2020，9，2： | 1 |
| 2 | Effect of naloxone on level of plasma beta-endorphin in neonates with severe asphyxia显示文摘BACKGROUND: β-endorphin is the most actively endogenous substance of cerebral endorphin. When combined with opiate receptor specially,it manifests a strong morphine-like activity and can decrease sensitivity of central nervous system to carbon dioxide so as to inhibit breath. OBJECTIVE: To observe the changes of content of plasma β-endorphin in neonates with severe asphyxia after naloxone treatment in a large dosage. DESIGN: Randomized controlled observation. SETTINGS: Department of Pediatrics,Shenzhen Shajing People's Hospital; Center of Pediatrics,Guangzhou Zhujiang Hospital. PARTICIPANTS: A total of 97 neonates with severe asphyxia including 57 boys and 40 girls were selected from Neonatal Intensive Care Unit,Department of Pediatrics,Shenzhen Shajing People's Hospital from January 2004 to November 2005. Their gestational age was (38±3) weeks,body mass was (3.2±1.7) kg,and hospitalization duration was (2.8±2.3) hours. All neonates met the diagnostic criteria of with severe asphyxia and all their parents provided the confirmed consent. METHODS: All neonates were treated with inspired oxygen,sedation,stopping terror,decreasing cranial pressure,maintaining a well blood perfusion and normal level of blood glucose (about 5.0 mmol/L). After hospitalization,0.1 mg/(kg·d) naloxone hydrochloride (Beijing Sihuan Pharmaceutical Technology Co.,Ltd.; certification: H10900021; bullet preparation; 0.4 mg/ampoule) was intravenously dribbled into neonates for 4–6 hours,14 days in total. 2 mL blood was collected from radial artery in neonates at the beginning of hospitalization and at 3 days after naloxone treatment,put in aprotinin-pre-cool tube,mixed evenly,and centrifuged at hypothermia. Plasma was maintained in refrigerator at –70 ℃. The kit was provided by Neurobiology Department of Shanghai Second Military Medical University of Chinese PLA. Concentration of plasma β-endorphin was measured by using radio-immunity assay.All data were expressed as Mean± SD and results were compared with paired t test. MAIN OUTCOME MEASURE: Concentration of plasma β-endorphin. RESULTS: All 97 neonates were involved in the final analysis. Concentration of plasma β-endorphin in neonates with severe asphyxia was lower after treatment as compared with that before treatment,and there was significant difference (t =10.31,P < 0.01). CONCLUSION: Naloxone can decrease level of plasma β-endorphin in neonates with severe asphyxia. | Yinghong Wang Ling Xu Lijun Xue Yi Xiao Yangjun Liu Lingyan Huang | 2007 | Neural Regeneration Research2007，2，10： | 1 |
| 3 | A MATLAB code for the material-field series-expansion topology optimization method显示文摘This paper presents a MATLAB implementation of the material-field series-expansion(MFSE)topology optimization method.The MFSE method uses a bounded material field with specified spatial correlation to represent the structural topology.With the series-expansion method for bounded fields,this material field is described with the characteristic base functions and the corresponding coefficients.Compared with the conventional density-based method,the MFSE method decouples the topological description and the finite element discretization,and greatly reduces the number of design variables after dimensionality reduction.Other features of this method include inherent control on structural topological complexity,crisp structural boundary description,mesh independence,and being free from the checkerboard pattern.With the focus on the implementation of the MFSE method,the present MATLAB code uses the maximum stiffness optimization problems solved with a gradientbased optimizer as examples.The MATLAB code consists of three parts,namely,the main program and two subroutines(one for aggregating the optimization constraints and the other about the method of moving asymptotes optimizer).The implementation of the code and its extensions to topology optimization problems with multiple load cases and passive elements are discussed in detail.The code is intended for researchers who are interested in this method and want to get started with it quickly.It can also be used as a basis for handling complex engineering optimization problems by combining the MFSE topology optimization method with non-gradient optimization algorithms without sensitivity information because only a few design variables are required to describe relatively complex structural topology and smooth structural boundaries using the MFSE method. | Pai LIU Xiaopeng ZHANG Yangjun LUO Yi YAN | 2021 | Frontiers of Mechanical Engineering2021，16，3： | 1 |
| 4 | Progress and perspective of high strain NBT-based lead-free piezoceramics and multilayer actuators显示文摘In this review,the evolution of high strain Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoceramics and their multilayer actuators has been explored.First,in terms of Na_(0.5)Bi_(0.5)TiO_(3)-based ceramic materials,the origin of high strain,the typical chemical modification methods of obtaining large strain and extrinsic factors affecting the large strain are discussed.Then it briefly summarizes the problems existing in Na_(0.5)Bi_(0.5)TiO_(3)-based ceramics for multilayer actuator applications.Strategies to optimize strain performance by means of microstructure control and phase structure design are also discussed.Thereafter,in terms of multilayer actuator,we describe its characteristics,applications and preparation process systematically,as well as the recent development of Na_(0.5)Bi_(0.5)TiO_(3)-based multilayer actuator.At last,perspectives on directions of following work and promising fields for the applications of the materials and their devices are presented. | Pengyuan Fan Kai Liu Weigang Ma Hua Tan Qi Zhang Ling Zhang Changrong Zhou David Salamon Shan-Tao Zhang Yangjun Zhang Bo Nan Haibo Zhang | 2021 | Journal of Materiomics2021，7，3： | 1 |
| 5 | Real-Time Instability Detection of Centrifugal Compressors Based on Motor Speed Measurements显示文摘Flow instability in the centrifugal compressor should be detected and avoided for stable and safe operation.Due to the popularity of electric centrifugal compressors,instability detection could be achieved by measuring motor signals instead of traditional aerodynamic signals.In this paper,the feasibility of instability detection by motor signals(i.e.rotating speed and phase current)was studied experimentally.The physical structure and control method of the electric centrifugal compressor were discussed to reveal the potential of instability detection by motor signals.Dynamic pressure signals and motor signals measured during unsteady experiments were analyzed in the time domain and frequency domain.Characteristics of these signals were then compared under different operating conditions to indicate the feasibility of instability detection by motor signals.Finally,the ability of Short-Time Fourier Transform(STFT)of rotating speed signals in real-time instability detection was discussed.Results showed that the rotating speed signal is a good alternate for instability detection in spite of signal distortion,while the phase current signal can only detect surge due to the low resolution of the controller.Based on the variations of the amplitude and frequency of rotating speed signals,the real-time instability can be captured accurately by STFT with a window size of 0.5 s.Besides,the interference caused by the controller can be removed by STFT. | CHEN Haoxiang ZHUGE Weilin QIAN Yuping ZHANG Yangjun LIU Hongdan | 2023 | Journal of Thermal Science2023，32，1： | 0 |
| 6 | Characterization of Swirling Inflow Effects on Turbine Performance under Pulsating Flows显示文摘The present study focuses on the influence of the swirling flows on flow behaviors and performance of a radial-flow turbocharger turbine under pulsating inflow condition.To characterize the effects of swirling flow,three sets of simulations of the turbine were carried out,which are an unsteady simulation under pulsating swirling inflow,an unsteady simulation under equivalent pulsating uniform inflow,and quasi-steady simulations under uniform inflow.Results proved that swirling flow has a considerable negative influence on turbine instantaneous performance and lead to 2.5%cycle-averaged efficiency reduction under pulsating flow condition.Swirling inflow would lead to significant losses in both the volute and the rotor,while the pulsating inflow leads to higher losses in the rotor and shows little influence on the losses in the volute.The instantaneous efficiency reduction of the turbine could be correlated with the time-varying inlet swirl strength.Under the influence of unsteady inlet swirls,the volute flow field is highly distorted and the free vortex relation is no longer valid.The swirling flow has strong interactions with the wake flow of the volute tongue,leading to additional losses.Relative flow angle at rotor inlet is remarkably reduced and its distribution is significantly distorted.Strong separation flows and passage vortices would appear in the rotor because of the swirling inflow,leading to inferior rotor performance. | DING Zhanming WANG Cuicui ZHANG Junyue LIU Ying HOU Linlin ZHUGE Weilin ZHANG Yangjun | 2022 | Journal of Thermal Science2022，31，5： | 0 |
| 7 | Fluorene-based narrow-band-gap copolymers for red lightemitting diodes and bulk heterojunction photovoltaic cells显示文摘A series of narrow band-gap conjugated copolymers(PFO-DDQ)derived from 9,9-dioctylfluorene(DOF)and 2,3-dimethyl-5,8-dithien-2-yl-quinoxalines(DDQ)is prepared by the palladium-catalyzed Suzuki coupling reaction with the molar feed ratio of DDQ at around 1%,5%,15%,30%and 50%,respectively.The obtained polymers are readily soluble in common organic solvents.The solutions and the thin solid films of the copolymers absorb light from 300-590 nm with two absorbance peaks at around 380 and 490 nm.The intensity of 490 nm peak increases with the increasing DDQ content in the polymers.Efficient energy transfer due to exciton trapping on narrow-band-gap DDQ sites has been observed.The PL emission consists exclusively of DDQ unit emission at around 591-643 nm depending on the DDQ content in solid film.The EL emission peaks are red-shifted from 580 nm for PFO-DDQ1 to 635 nm for PFO-DDQ50.The highest external quantum efficiency achieved with the device configuration ITO/PEDOT/PVK/PFO-DDQ15/Ba/Al is 1.33%with a luminous efficiency 1.54 cd/A.Bulk heterojunction photovoltaic cells fabricated from composite films of PFO-DDQ30 copolymer and[6,6]-phenyl C61 butyric acid methyl ester(PCBM)as electron donor and electron acceptor,respectively in device configuration:ITO/PEDOT:PSS/PFODDQ30:PCBM/PFPNBr/Al shows power conversion efficiencies of 1.18%with open-circuit voltage(V_(oc))of 0.90 V and short-circuit current density(J_(sc))of 2.66 mA/cm^(2)under an AM1.5 solar simulator(100 mW/cm^(2)).The photocurrent response wavelengths of the PVCs based on PFO-DDQ30/PCBM blends covers 300-700 nm.This indicates that these kinds of low band-gap polymers are promising candidates for polymeric solar cells and red light-emitting diodes. | Mingliang SUN Li WANG Yangjun XIA Bin DU Ransheng LIU Yong CAO | 2008 | Frontiers of Chemical Science and Engineering2008，2，3： | 0 |
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