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Sample records for non-minimum phase characteristic

  1. A unified model-free controller for switching minimum phase, non-minimum phase and time-delay systems

    CERN Document Server

    Michel, Loïc

    2012-01-01

    This preliminary work presents a simple derivation of the standard model-free control in order to control switching minimum phase, non-minimum phase and time-delay systems. The robustness of the proposed method is studied in simulation.

  2. Stable Inversion of MIMO Linear Discrete Time Non-Minimum Phase Systems

    NARCIS (Netherlands)

    George, Koshy; Verhaegen, Michel; Scherpen, Jacquelien M.A.

    1999-01-01

    A novel technique to achieve output tracking via stable inversion of non-minimum phase linear systems is presented wherein the desired signal is obtained from field measurements, and hence corrupted by noise. The earlier approach to stable inversion does not take into account the noise in the system

  3. Combined feedforward and model-assisted active disturbance rejection control for non-minimum phase system.

    Science.gov (United States)

    Sun, Li; Li, Donghai; Gao, Zhiqiang; Yang, Zhao; Zhao, Shen

    2016-09-01

    Control of the non-minimum phase (NMP) system is challenging, especially in the presence of modelling uncertainties and external disturbances. To this end, this paper presents a combined feedforward and model-assisted Active Disturbance Rejection Control (MADRC) strategy. Based on the nominal model, the feedforward controller is used to produce a tracking performance that has minimum settling time subject to a prescribed undershoot constraint. On the other hand, the unknown disturbances and uncertain dynamics beyond the nominal model are compensated by MADRC. Since the conventional Extended State Observer (ESO) is not suitable for the NMP system, a model-assisted ESO (MESO) is proposed based on the nominal observable canonical form. The convergence of MESO is proved in time domain. The stability, steady-state characteristics and robustness of the closed-loop system are analyzed in frequency domain. The proposed strategy has only one tuning parameter, i.e., the bandwidth of MESO, which can be readily determined with a prescribed robustness level. Some comparative examples are given to show the efficacy of the proposed method. This paper depicts a promising prospect of the model-assisted ADRC in dealing with complex systems.

  4. Robustification and Optimization in Repetitive Control For Minimum Phase and Non-Minimum Phase Systems

    Science.gov (United States)

    Prasitmeeboon, Pitcha

    repetitive control FIR compensator. The aim is to reduce the final error level by using real time frequency response model updates to successively increase the cutoff frequency, each time creating the improved model needed to produce convergence zero error up to the higher cutoff. Non-minimum phase systems present a difficult design challenge to the sister field of Iterative Learning Control. The third topic investigates to what extent the same challenges appear in RC. One challenge is that the intrinsic non-minimum phase zero mapped from continuous time is close to the pole of repetitive controller at +1 creating behavior similar to pole-zero cancellation. The near pole-zero cancellation causes slow learning at DC and low frequencies. The Min-Max cost function over the learning rate is presented. The Min-Max can be reformulated as a Quadratically Constrained Linear Programming problem. This approach is shown to be an RC design approach that addresses the main challenge of non-minimum phase systems to have a reasonable learning rate at DC. Although it was illustrated that using the Min-Max objective improves learning at DC and low frequencies compared to other designs, the method requires model accuracy at high frequencies. In the real world, models usually have error at high frequencies. The fourth topic addresses how one can merge the quadratic penalty to the Min-Max cost function to increase robustness at high frequencies. The topic also considers limiting the Min-Max optimization to some frequencies interval and applying an FIR zero-phase low-pass filter to cutoff the learning for frequencies above that interval.

  5. Analysis of Non-minimum Phase in Buck-Boost Converter

    OpenAIRE

    2016-01-01

    In this paper, relations among the parameters of the non-minimum phase for the Buck-Boost converter are studied. It is demonstrated that when the Buck-Boost converter works in Buck mode, the negative regulation voltage is determined by the converter with the pre-designed inductor and load as the duty ratio D0.382, and the duty ratio has a limited effect on the negative regulation voltage of the converter; when the Buck-Boost converter works in Boost mode,the negative regulation voltage is det...

  6. Analysis of Non-minimum Phase in Buck-Boost Converter

    Directory of Open Access Journals (Sweden)

    Huang Jinfeng

    2016-01-01

    Full Text Available In this paper, relations among the parameters of the non-minimum phase for the Buck-Boost converter are studied. It is demonstrated that when the Buck-Boost converter works in Buck mode, the negative regulation voltage is determined by the converter with the pre-designed inductor and load as the duty ratio D0.382, and the duty ratio has a limited effect on the negative regulation voltage of the converter; when the Buck-Boost converter works in Boost mode,the negative regulation voltage is determined jointly by the converter with its pre-designed inductor, load and duty cycle, for which performs that the higher the output voltage is (i.e., the greater the duty ratio is,the more severe undershoot of the voltage will be. The conclusion of this paper has a guidance meaning for decreasing the negative regulation voltage of the Buck-Boost converter. Finally the correctness of the analysis for the non-minimum phase is verified by simulations and experiments.

  7. Observation and output adaptive tracking for a class of nonlinear non-minimum phase systems

    Science.gov (United States)

    Bartolini, G.; Estrada, A.; Punta, E.

    2016-09-01

    In this paper, the output tracking problem for a class of systems with unstable zero dynamics is addressed. The state is assumed not measurable. The output of the dynamical system to be controlled has to track a signal, which is the sum of a known number of sinusoids with unknown frequencies, amplitudes and phases. The non-minimum phase nature of the considered systems prevents the direct tracking by standard sliding mode methods, which are known to generate unstable behaviours of the internal dynamics. The proposed method relies on the availability of a flat output and its time derivatives which are functions of the unavailable state; therefore, a nonlinear observer is needed. Due to the uncertainty in the frequencies and in the parameters defining the relationship between the output of the system and the flat states, adaptive indirect methods are applied.

  8. Design of Critical Control Systems for Non-Minimum Phase Plants via LTR Technique

    Science.gov (United States)

    Ishihara, Tadashi; Ono, Takahiko

    An application of the loop transfer recovery (LTR) technique to critical control systems design is proposed for non-minimum phase plants. The controller structure is chosen as the Davison type integral controller with the Kalman filter. First, a critical control system is designed on the assumption that the state of the minimum phase part of the plant can be used for the feedback. A quadratic performance index with tuning parameters is used for determining the partial state feedback gain matrix. Second, the Kalman filter gain matrix is determined such that the output feedback controller performs as in the partial state feedback controller. The formal partial loop recovery procedure using the Riccati equation is adopted for this purpose. The proposed design method requires much simpler numerical search than the conventional one-step approach. An illustrative design example is presented.

  9. Fault diagnosis for non-minimum phase systems using ℋ∞ optimization

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob

    2001-01-01

    The analysis and design algorithms for residual generators for nonminimum phase systems are given. It is shown that the ℋ∞ optimization of residual generators applied directly to systems including nonminimum phase zeros can be very conservative. To remove this conservatism in the ℋ∞ opt...

  10. Parameter selection and analysis of non-minimum phase for Boost converter%Boost变换器的参数选择与非最小相位分析

    Institute of Scientific and Technical Information of China (English)

    皇金锋; 刘树林

    2014-01-01

    In order to improve the Boost converter 's transient performance and reduce the negative over-shoot effect because of non-minimum-phase reaction on system, the small signal mathematics model of Boost converter worked in inductor current continuous mode was established with pulse waveform integral method. The transfer functions from input to output and from control to output were obtained. The theo-retical basis for the Boost converter transient performance optimization was provided. The effect of transi-ent performances and negative over-shoot on there parameters such as inductance, capacitance, load, du-ty ratio and frequency were analyzed with the mathematics model. Research results show that the larger the inductance, the heavy load, large duty can make the system zero near the origin, and the over-shoot phenomenon is more obvious because of non-minimum-phase reaction on system. Different capacitance values have an impact on transient performance and output voltage ripple and have no effect on the over-shoot phenomenon. The principle of parameter selection for improving system transient performance and reducing non-minimum-phase reaction were given. The theoretical basis for optimal design of Boost con-verter was provided. The simulation and experimental results verify the rationality of the parameter selec-tion.%为了提高Boost变换器的暂态性能,减小非最小相位反应引起的负调对系统的影响,利用脉冲波形积分法建立了Boost变换器工作在电感电流连续模式下的小信号数学模型,获得了系统输入-输出以及控制-输出的传递函数,为Boost变换器暂态性能优化提供了理论依据。利用该模型分析了电感、电容、负载、占空比、频率等参数对系统暂态性能和系统非最小相位引起的负调电压的影响。研究结果表明:较大的电感、最重负载、较大的占空比使得系统的零点更靠近原点,系统的非最小相位反应即负调现象更

  11. Sex Differences in Countermovement Jump Phase Characteristics

    National Research Council Canada - National Science Library

    McMahon, John; Rej, Sophie; Comfort, Paul

    2017-01-01

    .... The purpose of this study was to explore differences in CMJ phase characteristics between male and female athletes by comparing the force-, power-, velocity-, and displacement-time curves throughout...

  12. Sex Differences in Countermovement Jump Phase Characteristics

    Directory of Open Access Journals (Sweden)

    John J. McMahon

    2017-01-01

    Full Text Available The countermovement jump (CMJ is commonly used to explore sex differences in neuromuscular function, but previous studies have only reported gross CMJ measures or have partly examined CMJ phase characteristics. The purpose of this study was to explore differences in CMJ phase characteristics between male and female athletes by comparing the force-, power-, velocity-, and displacement-time curves throughout the entire CMJ, in addition to gross measures. Fourteen men and fourteen women performed three CMJs on a force platform from which a range of kinetic and kinematic variables were calculated via forward dynamics. Jump height (JH, reactive strength index modified, relative peak concentric power, and eccentric and concentric displacement, velocity, and relative impulse were all greater for men (g = 0.58–1.79. Relative force-time curves were similar between sexes, but relative power-, velocity-, and displacement-time curves were greater for men at 90%–95% (immediately before and after peak power, 47%–54% (start of eccentric phase and 85%–100% (latter half of concentric phase, and 65%–87% (bottom of countermovement and initial concentric phase of normalized jump time, respectively. The CMJ distinguished between sexes, with men demonstrating greater JH through applying a larger concentric impulse and, thus, achieving greater velocity throughout most of the concentric phase, including take-off.

  13. Characteristics of the new phase in CDT

    Energy Technology Data Exchange (ETDEWEB)

    Ambjoern, J. [Copenhagen University, The Niels Bohr Institute, Copenhagen Oe (Denmark); Radboud University, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Nijmegen (Netherlands); Gizbert-Studnicki, J.; Jurkiewicz, J. [Jagiellonian University, Institute of Physics, Krakow (Poland); Goerlich, A. [Copenhagen University, The Niels Bohr Institute, Copenhagen Oe (Denmark); Jagiellonian University, Institute of Physics, Krakow (Poland); Klitgaard, N.; Loll, R. [Radboud University, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Nijmegen (Netherlands)

    2017-03-15

    The approach of Causal Dynamical Triangulations (CDT), a candidate theory of nonperturbative quantum gravity in 4D, turns out to have a rich phase structure. We investigate the recently discovered bifurcation phase C{sub b} and relate some of its characteristics to the presence of singular vertices of very high order. The transition lines separating this phase from the ''time-collapsed'' B-phase and the de Sitter phase C{sub dS} are of great interest when searching for physical scaling limits. The work presented here sheds light on the mechanisms behind these transitions. First, we study how the B-C{sub b} transition signal depends on the volume fixing implemented in the simulations, and find results compatible with the previously determined second-order character of the transition. The transition persists in a transfer matrix formulation, where the system's time extension is taken to be minimal. Second, we relate the new C{sub b}-C{sub dS} transition to the appearance of singular vertices, which leads to a direct physical interpretation in terms of a breaking of the homogeneity and isotropy observed in the de Sitter phase when crossing from C{sub dS} to the bifurcation phase C{sub b}. (orig.)

  14. Characteristics of the new phase in CDT

    CERN Document Server

    Ambjørn, J; Görlich, A; Jurkiewicz, J; Klitgaard, N; Loll, R

    2016-01-01

    Causal Dynamical Triangulations (CDT), a candidate theory of nonperturbative quantum gravity in 4D, turns out to have a rich phase structure. We investigate the recently discovered bifurcation phase $C_b$ and relate some of its characteristics to the presence of singular vertices of very high order. The transition lines separating this phase from the "time-collapsed" $B$-phase and the de Sitter phase $C_{dS}$ are of great interest when searching for physical scaling limits. The work presented here sheds light on the mechanisms behind these transitions. First, we study how the $B$-$C_b$ transition signal depends on the volume-fixing implemented in the simulations, and find results compatible with the previously determined second-order character of the transition. The transition persists in a transfer matrix formulation, where the system's time extension is taken to be minimal. Second, we relate the new $C_b$-$C_{dS}$ transition to the appearance of singular vertices, which leads to a direct physical interpreta...

  15. Non-Minimum Phase Nonlinear System Predictive Control Based on Local Recurrent Neural Networks

    Institute of Scientific and Technical Information of China (English)

    张燕; 陈增强; 袁著祉

    2003-01-01

    After a recursive multi-step-ahead predictor for nonlinear systems based on local recurrent neural networks is introduced, an intelligent PID controller is adopted to correct the errors including identified model errors and accumulated errors produced in the recursive process. Characterized by predictive control, this method can achieve a good control accuracy and has good robustness. A simulation study shows that this control algorithm is very effective.

  16. Endurance characteristics of phase change memory cells

    Science.gov (United States)

    Ruru, Huo; Daolin, Cai; Chen, Bomy; Yifeng, Chen; Yuchan, Wang; Yueqing, Wang; Hongyang, Wei; Qing, Wang; Yangyang, Xia; Dan, Gao; Zhitang, Song

    2016-05-01

    The endurance characteristics of phase change memory are studied. With operational cycles, the resistances of reset and set states gradually change to the opposite direction. What is more, the operational conditions that are needed are also discussed. The failure and the changes are concerned with the compositional change of the phase change material. An abnormal phenomenon that the threshold voltage decreases slightly at first and then increases is observed, which is due to the coaction of interface contact and growing active volume size changing. Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA09020402), the National Key Basic Research Program of China (Nos. 2013CBA01900, 2010CB934300, 2011CBA00607, 2011CB932804), the National Integrate Circuit Research Program of China (No. 2009ZX02023-003), the National Natural Science Foundation of China (No. 61176122, 61106001, 61261160500, 61376006), and the Science and Technology Council of Shanghai (Nos. 12nm0503701, 13DZ2295700, 12QA1403900, 13ZR1447200, 14ZR1447500).

  17. Association between lunar phase and sleep characteristics.

    Science.gov (United States)

    Turányi, Csilla Zita; Rónai, Katalin Zsuzsanna; Zoller, Rezső; Véber, Orsolya; Czira, Mária Eszter; Újszászi, Ákos; László, Gergely; Szentkirályi, András; Dunai, Andrea; Lindner, Anett; Szőcs, Julianna Luca; Becze, Ádám; Kelemen, Andrea; Lendvai, Zsófia; Molnar, Miklos Z; Mucsi, István; Novák, Márta

    2014-11-01

    Popular belief holds that the lunar cycle affects human physiology, behavior, and health, including sleep. To date, only a few and conflicting analyses have been published about the association between lunar phases and sleep. Our aim was to analyze the relationship between lunar phases and sleep characteristics. In this retrospective, cross-sectional analysis, data from 319 patients who had been referred for sleep study were included. Individuals with apnea-hypopnea index ≥ 15/h were excluded. Socio-demographic parameters were recorded. All participants underwent one-night standard polysomnography. Associations between lunar cycle (new moon, full moon and alternate moon) and sleep parameters were examined in unadjusted and adjusted models. Fifty-seven percent of patients were males. Mean age for men was 45 ± 14 years and 51 ± 12 years for women. In total, 224 persons had their sleep study done during alternate moon, 47 during full moon, and 48 during new moon. Full moon was associated with lower sleep efficiency [median (%) (IQR): new moon 82 (18), full moon 74 (19), alternate moon 82 (15); P full moon 6 (4), alternate moon 11 (9); P full moon 137 (152), alternate moon 97 (76); P full moon. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. On Group Phase Quantization and Its Physical Characteristics

    Institute of Scientific and Technical Information of China (English)

    DU Bao-Qiang; ZHOU Wei; YU Jian-Guo; DONG Shao-Feng

    2011-01-01

    The physical characteristics of phase quantum are further revealed, based on the proposition of concepts of the greatest common factor frequency, the least common multiple period, quantized phase shift resolution and equivalent phase comparison frequency. Then the problem of phase comparison between different frequency signals is certified in detail. Using the basic principle of phase comparison between different frequencies and the variation law of group phase difference, a point of view on group phase quantization is presented. Group phase quantum is not only an indivisible individual of group phase, but also a basic unit composing group phase difference. It is equal to the equivalent phase comparison period of phase comparison between different frequencies in size. Experimental results show not only a high measurement resolution of 10-12/s in frequency measurement based on group phase quantum, but also a super-high locked phase precision of 10-13/s in active H atomic clock.%@@ The physical characteristics of phase quantum are further revealed,based on the proposition of concepts of the greatest common factor frequency,the least common multiple period,quantized phase shift resolution and equivalent phase comparison frequency.Then the problem of phase comparison between different frequency signals is certified in detail.Using the basic principle of phase comparison between different frequencies and the variation law of group phase difference,a point of view on group phase quantization is presented.Group phase quantum is not only an indivisible individual of group phase,but also a basic unit composing group phase difference.It is equal to the equivalent phase comparison period of phase comparison between different frequencies in size.Experimental results show not only a high measurement resolution of 10-12 /s in frequency measurement based on group phase quantum,but also a super-high locked phase precision of 10-13/s in active H atomic clock.

  19. Melting Characteristics and Wettability of Binding Phase in Sinter

    Institute of Scientific and Technical Information of China (English)

    SHEN Feng-man; LI Guang-sen; DING Zhi-min; MU Lin

    2009-01-01

    The melting characteristics and wettability of the binding phase in high basicity sinter were studied.By changing nCaO:nFe2O3 (molar ratio of CaO to Fe2O3) as well as the percentage of MgO,SiO2,and Al2O3,the melting characteristics and wettability of the binding phase were discussed.The results indicated that the characteristic melting temperature was the lowest and wettability was the best at nCaO:nFe2O3=1:1 (without addition); the addition of MgO increased the characteristic melting temperature and contact angles; when the percentage of SiO2 or Al2O3 was 3%,the characteristic melting temperature was the lowest,whereas the contact angles increased with an increase in SiO2 and Al2O3 contents.

  20. Design of RTDA controller for industrial process using SOPDT model with minimum or non-minimum zero.

    Science.gov (United States)

    Anbarasan, K; Srinivasan, K

    2015-07-01

    This research paper focuses on the design and development of simplified RTDA control law computation formulae for SOPDT process with minimum or non-minimum zero. The design of RTDA control scheme consists of three main components namely process output prediction, model prediction update and control action computation. The systematic approach for computation of the above three components for SOPDT process with minimum or non-minimum zero is developed in this paper. The design, implementation and performance evaluation of the developed controller is demonstrated via simulation examples. The closed loop equation, block diagram representation and theoretical stability derivation for RTDA controller are developed. The performance of proposed controller is compared with IMC, SPC, MPC and PID controller and it is demonstrated on Industrial non-linear CSTR process.

  1. Phase Radiation Characteristics of an Open-Ended Circular Waveguide

    DEFF Research Database (Denmark)

    Shishkova, A.V.; Pivnenko, Sergiy; Kim, O.S.

    2002-01-01

    Analytic expressions for phase radiation characteristics of a semi-infinite open-ended circular waveguide regardless of its aperture size and operating frequency have been obtained making use of the rigorous Weinstein's theory. The analysis of phase radiation patterns has been carried out...... for the dominant mode (TE11) as well as for the high order modes TM01 and TE01, both for a single and multimode propagation. The measurement of radiation characteristics of an open-ended circular waveguide has been carried out at the DTU-ESA Spherical Near-Field Antenna Test Facility. It is shown...

  2. SIMULATION OF CHARACTERISTICS OF DUAL-CORE PHASE SHIFTING TRANSFORMER

    Directory of Open Access Journals (Sweden)

    Kalinin L.P.

    2014-04-01

    Full Text Available The role and importance of phase shifting transformers are increased as a result of the further development of integrated power systems. This gives the rise to new technical solutions which entails the necessity of comparison of new developments with existing. The article consider the technical characteristics of dual-core phase shifting transformer which later will be used as a basis for comparison with other competing options and assess of their technical efficiency.

  3. Dynamic characteristics of an NC table with phase space reconstruction

    Institute of Scientific and Technical Information of China (English)

    Linhong WANG; Bo WU; Runsheng DU; Shuzi YANG

    2009-01-01

    The dynamic properties of a numerical control (NC) table directly interfere with the accuracy and surface quality of work pieces machined by a computer numerical control (CNC) machine. Phase space reconstruction is an effective approach for researching dynamic behaviors of a system with measured time series. Based on the theory and method for phase space reconstruction, the correlation dimension, maximum Lyapunov exponent, and dynamic time series measured from the NC table were analyzed. The characteristic quantities such as the power spectrum, phase trajectories, correlation dimension, and maximum Lyapunov exponent are extracted from the measured time series. The chaotic characteristic of the dynamic properties of the NC table is revealed via various approaches.Therefore, an NC table is a nonlinear dynamic system. This research establishes a basis for dynamic system discrimi-nation of a CNC machine.

  4. Damage Characteristic of Interpenetrating Phase Composites under Dynamic Loading

    Institute of Scientific and Technical Information of China (English)

    WANG Fuchi; ZHANG Xu; WANG Yangwei; WANG Lu; MA Zhuang; FAN Qunbo

    2014-01-01

    In order to investigate the damage characteristic of ceramic-metal interpenetrating phase composite (IPC) under dynamic loading, uniaxial dynamic compression was performed to characterize the failure of SiC/Al composite with 15%porosity using a modified Split Hopkinson Pressure Bar (SHPB). High speed photography was used to capture the failure procedure and set up the relationship between deformation and real stress. The deformation control technology was used to obtain collected samples in different deformations under dynamic loading. Micro CT technology was utilized to acquire real damage distribution of these specimens. Moreover, SEM was employed in comparing the damage characteristics in IPC. A summary of the available experimental results showed that IPC without lateral confinement formed double cones. The different features compared with ceramic materials without restraint was shown to be the result of the lateral restraint effect provided by metal phase to ceramics skeleton.

  5. Dimensionless ratios: Characteristics of quantum liquids and their phase transitions

    Science.gov (United States)

    Yu, Yi-Cong; Chen, Yang-Yang; Lin, Hai-Qing; Römer, Rudolf A.; Guan, Xi-Wen

    2016-11-01

    Dimensionless ratios of physical properties can characterize low-temperature phases in a wide variety of materials. As such, the Wilson ratio (WR), the Kadowaki-Woods ratio, and the Wiedemann-Franz law capture essential features of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases of many-body interacting multicomponent quantum liquids in one dimension (1D) can be described by WRs based on the compressibility, susceptibility, and specific heat associated with each component. These WRs arise due to additivity rules within subsystems reminiscent of the rules for multiresistor networks in series and parallel—a novel and useful characteristic of multicomponent Tomonaga-Luttinger liquids (TLL) independent of microscopic details of the systems. Using experimentally realized multispecies cold atomic gases as examples, we prove that the Wilson ratios uniquely identify phases of TLL, while providing universal scaling relations at the boundaries between phases. Their values within a phase are solely determined by the stiffnesses and sound velocities of subsystems and identify the internal degrees of freedom of said phase such as its spin degeneracy. This finding can be directly applied to a wide range of 1D many-body systems and reveals deep physical insights into recent experimental measurements of the universal thermodynamics in ultracold atoms and spins.

  6. [Biological characteristics of the egg phase of citrus root weevils].

    Science.gov (United States)

    Guedes, Jerson V C; Parra, José R P

    2007-01-01

    The goal of this work was to study some characteristics of the egg phase of three species of citrus root weevils. The insects were collected from citrus plants in Itapetininga, SP, and brought to the Laboratório de Biologia de Insetos of ESALQ/USP, in Piracicaba, SP, where the species Naupactus cervinus (Boheman), Naupactus versatilis (Hustache) and Parapantomorus fluctuosus (Boheman) were kept. Duration and viability of the egg phase were evaluated, and the lower temperature threshold and thermal constant (K) were calculated for these species. The species of citrus root weevils showed different duration of egg phases. The egg phase ranged from 40.4 to 13.8 N. cervinus, from 38.7 to 20.0 days for N. versatilis, and from 35.0 to 13.8 days for P. fluctuosus, depending upon temperature. The temperature thresholds of this stage were 8.1, 8.3, and 9.9 masculineC at thermal constant was 385.7, 397.7 and 294.1 degree-days, for N. cervinus, N. versatilis and P. fluctuosus respectively. The duration of the egg phases of N. cervinus and N. versatilis were similar at the same temperatures and P. fluctuosus had a faster development than Naupactus spp. in all temperatures tested.

  7. Enhanced IMC based PID controller design for non-minimum phase (NMP) integrating processes with time delays.

    Science.gov (United States)

    Ghousiya Begum, K; Seshagiri Rao, A; Radhakrishnan, T K

    2017-03-18

    Internal model control (IMC) with optimal H2 minimization framework is proposed in this paper for design of proportional-integral-derivative (PID) controllers. The controller design is addressed for integrating and double integrating time delay processes with right half plane (RHP) zeros. Blaschke product is used to derive the optimal controller. There is a single adjustable closed loop tuning parameter for controller design. Systematic guidelines are provided for selection of this tuning parameter based on maximum sensitivity. Simulation studies have been carried out on various integrating time delay processes to show the advantages of the proposed method. The proposed controller provides enhanced closed loop performances when compared to recently reported methods in the literature. Quantitative comparative analysis has been carried out using the performance indices, Integral Absolute Error (IAE) and Total Variation (TV).

  8. Characteristics of the chiral phase transition in nonlocal quark models

    CERN Document Server

    Dumm, D G

    2004-01-01

    The characteristics of the chiral phase transition are analyzed within the framework of chiral quark models with nonlocal interactions in the mean field approximation (MFA). In the chiral limit, we show that there is a region of low values of the chemical potential in which the transition is a second order one. In that region, it is possible to perform a Landau expansion and determine the critical exponents which, as expected, turn out to be the MFA ones. Our analysis also allows to obtain semi-analytical expressions for the transition curve and the location of the tricritical point. For the case of finite current quark masses, we study the behavior of various thermodynamical and chiral response functions across the phase transition.

  9. MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    V.S. Malyar

    2016-06-01

    Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.

  10. Mechanical parameters and flight phase characteristics in aquatic plyometric jumping.

    Science.gov (United States)

    Louder, Talin J; Searle, Cade J; Bressel, Eadric

    2016-09-01

    Plyometric jumping is a commonly prescribed method of training focused on the development of reactive strength and high-velocity concentric power. Literature suggests that aquatic plyometric training may be a low-impact, effective supplement to land-based training. The purpose of the present study was to quantify acute, biomechanical characteristics of the take-off and flight phase for plyometric movements performed in the water. Kinetic force platform data from 12 young, male adults were collected for counter-movement jumps performed on land and in water at two different immersion depths. The specificity of jumps between environmental conditions was assessed using kinetic measures, temporal characteristics, and an assessment of the statistical relationship between take-off velocity and time in the air. Greater peak mechanical power was observed for jumps performed in the water, and was influenced by immersion depth. Additionally, the data suggest that, in the water, the statistical relationship between take-off velocity and time in air is quadratic. Results highlight the potential application of aquatic plyometric training as a cross-training tool for improving mechanical power and suggest that water immersion depth and fluid drag play key roles in the specificity of the take-off phase for jumping movements performed in the water.

  11. Phases and phase transition in insoluble and adsorbed monolayers of amide amphiphiles: Specific characteristics of the condensed phases.

    Science.gov (United States)

    Vollhardt, D

    2015-08-01

    For understanding the role of amide containing amphiphiles in inherently complex biological processes, monolayers at the air-water interface are used as simple biomimetic model systems. The specific characteristics of the condensed phases and phase transition in insoluble and adsorbed monolayers of amide amphiphiles are surveyed to highlight the effect of the chemical structure of the amide amphiphiles on the interfacial interactions in model monolayers. The mesoscopic topography and/or two-dimensional lattice structures of selected amino acid amphiphiles, amphiphilic N-alkylaldonamide, amide amphiphiles with specific tailored headgroups, such as amide amphiphiles based on derivatized ethanolamine, e.g. acylethanolamines (NAEs) and N-,O-diacylethanolamines (DAEs) are presented. Special attention is devoted the dominance of N,O-diacylated ethanolamine in mixed amphiphilic acid amide monolayers. The evidence that a first order phase transition can occur in adsorption layers and that condensed phase domains of mesoscopic scale can be formed in adsorption layers was first obtained on the basis of the experimental characteristics of a tailored amide amphiphile. New thermodynamic and kinetic concepts for the theoretical description of the characteristics of amide amphiphile's monolayers were developed. In particular, the equation of state for Langmuir monolayers generalized for the case that one, two or more phase transitions occur, and the new theory for phase transition in adsorbed monolayers are experimentally confirmed at first by amide amphiphile monolayers. Despite the significant progress made towards the understanding the model systems, these model studies are still limited to transfer the gained knowledge to biological systems where the fundamental physical principles are operative in the same way. The study of biomimetic systems, as described in this review, is only a first step in this direction.

  12. Noise characteristics of x-ray differential phase contrast CT

    Science.gov (United States)

    Zambelli, Joseph; Li, Ke; Bevins, Nicholas; Qi, Zhihua; Chen, Guang-Hong

    2011-03-01

    The noise characteristics of x-ray differential phase contrast computed tomography (DPC-CT) were investigated. Both theoretical derivation and experimental results demonstrated that the dependence of noise variance on spatial resolution in DPC-CT follows an inverse linear law. This behavior distinguishes DPC-CT from conventional absorption based x-ray CT, where the noise variance varies inversely with the cube of the spatial resolution. This anomalous noise behavior in DPC-CT is due to the Hilbert filtering kernel used in the CT reconstruction algorithm, which equally weights all spatial frequency content. Additionally, we demonstrate that the noise power of DPC-CT is scaled by the inverse of spatial frequency and is highly concentrated at the low spatial frequencies, whereas conventional absorption CT increases in power at the high spatial frequencies.

  13. Study of Characteristic Phases of a Kind of Lossless Even Symmetry Networks

    Institute of Scientific and Technical Information of China (English)

    LIANGChanghong; LILong

    2004-01-01

    It is well known that the lossless networks are the favorable approximate models of the small lossy devices or components in the realistic applications. Some special properties in a lossless network can be reduced to the invariance of the amplitudes and characteristic phases of the network S parameters. This paper gives a rigorous analysis of the characteristic phases of a kind of loss lesseven symmetry networks. The relations of characteristic phases of the lossless three-port and four-port even symmetries are presented. It is important and meaningful to check up the results of the numerical computations and experiments by using the relations of the characteristic phases. Some illustrations are given to show the applications of the characteristic phases.

  14. On the possibility of using the phase characteristic of a ring interferometer in microoptical gyroscopes

    Energy Technology Data Exchange (ETDEWEB)

    Venediktov, V Yu [Department of Physics, St. Petersburg State University, St. Petersburg (Russian Federation); Filatov, Yu V; Shalymov, E V [St. Petersburg Electrotechnical University " LETI" , St. Petersburg (Russian Federation)

    2014-12-31

    The prototype schemes of a microoptical gyroscope (MOG) developed to date on the basis of passive ring cavities imply the use of the amplitude characteristic only, since they operate using the dip in the transmission coefficient. We have analysed the possibility of creating a MOG, in which the phase characteristic is used as well. The phase characteristic of a ring interferometer has distinctive features in the vicinity of the cavity eigenfrequencies, which may be used to determine the angular velocity. A method for the angular velocity determination using both the phase and the amplitude characteristics of the interferometer is considered. (laser gyroscopes)

  15. Measurement of characteristics and phase modulation accuracy increase of LC SLM "HoloEye PLUTO VIS"

    Science.gov (United States)

    Bondareva, A. P.; Cheremkhin, P. A.; Evtikhiev, N. N.; Krasnov, V. V.; Starikov, R. S.; Starikov, S. N.

    2014-09-01

    Phase liquid crystal spatial light modulators (LC SLM) are actively integrated in various optical systems for dynamic diffractive optical elements imaging. To achieve the best performance, high stability and linearity of phase modulation is required. This article presents results of measurement of characteristics and phase modulation accuracy increase of state of the art LC SLM with HD resolution "HoloEye PLUTO VIS".

  16. Force-Time Characteristics and Running Velocity of Male Sprinters During the Acceleration Phase of Sprinting.

    Science.gov (United States)

    Mero, Antti

    1988-01-01

    Investigation of the force-time characteristics of eight male sprinters during the acceleration phase of the sprint start suggested that the braking and propulsion phases occur immediately after the block phase and that muscle strength strongly affects running velocity in the sprint start. (Author/CB)

  17. Functional phases and angular momentum characteristics of Tkatchev and Kovacs.

    Science.gov (United States)

    Irwin, Gareth; Exell, Timothy A; Manning, Michelle L; Kerwin, David G

    2017-03-01

    Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase.

  18. Equalization Technique for Balancing the Modulation Ratio Characteristics of the Single-Phase-to-Three-Phase Matrix Converter

    Directory of Open Access Journals (Sweden)

    Vengadeshwaran Velu

    2016-01-01

    Full Text Available Three-phase system has numerous advantages over the single-phase system in terms of instantaneous power, stability, and cost. Three-phase systems are not available in every location particularly in remote rural areas, hill stations, low voltage distribution homes, and so forth. Having a system that is capable of converting directly the readily available single-phase system to three phases will have greater usability in various applications. The routine techniques adopted in the direct ac-ac single-phase-to-three-phase converters do not yield the best desired outputs because of their complexity in the segregation process and bidirectional nature of the input signal. Other initiatives use ac-dc-ac converters which are huge and costly due to dc link energy storage devices. Further, none of these systems provide a convincing result in producing the standard three-phase output voltages that are 120° away from each other. This paper proposes an effective direct ac-ac single-phase-to-three-phase conversion technique based on space vector pulse width modulation based matrix converter system that produces a convincing three-phase output signals from a single-phase source with balanced modulation index characteristics. The details of the scientific programming adopted on the proposed technique were presented.

  19. Phase radiation characteristics of an open-ended circular waveguide

    DEFF Research Database (Denmark)

    Shishkova, Anna; Pivnenko, Sergey; Kim, Oleksiy S.

    2007-01-01

    General analytical expressions are derived for the far-field amplitude and phase radiation patterns of an open-ended circular waveguide (OE-CWG) regardless of its radius or the operation frequency for the dominant and symmetric higher-order excitation modes. The derivation is based on the rigorous...... solution to the problem of diffraction at an open end of a waveguide proposed by Weinstein. The near-field amplitude and phase patterns of an OE-CWG are then calculated using the spherical wave expansion technique. The measurement of the radiation pattern of an OE-CWG was carried out to verify the validity...

  20. Characteristics of phase-averaged equations for modulated wave groups

    NARCIS (Netherlands)

    Klopman, G.; Petit, H.A.H.; Battjes, J.A.

    2000-01-01

    The project concerns the influence of long waves on coastal morphology. The modelling of the combined motion of the long waves and short waves in the horizontal plane is done by phase-averaging over the short wave motion and using intra-wave modelling for the long waves, see e.g. Roelvink (1993). Th

  1. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    Science.gov (United States)

    Qazi, H. I. A.; Nie, Qiu-Yue; Li, He-Ping; Zhang, Xiao-Fei; Bao, Cheng-Yu

    2015-12-01

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A-X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  2. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    Energy Technology Data Exchange (ETDEWEB)

    Qazi, H. I. A.; Li, He-Ping, E-mail: liheping@tsinghua.edu.cn; Zhang, Xiao-Fei; Bao, Cheng-Yu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Nie, Qiu-Yue [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, Heilongjiang Province 150001 (China)

    2015-12-15

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  3. Standard guide for evaluating performance characteristics of phased-Array ultrasonic testing instruments and systems

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This guide describes procedures for evaluating some performance characteristics of phased-array ultrasonic examination instruments and systems. 1.2 Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with this guide are expressed in terms that relate to their potential usefulness for ultrasonic examinations. Other electronic instrument characteristics in phased-array units are similar to non-phased-array units and may be measured as described in E 1065 or E 1324. 1.3 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated. 1.4 This guide establishes no performance limits for examination systems; if such acceptance criteria ar...

  4. Phase characteristics of electromagnetically induced transparency analogue in coupled resonant systems

    CERN Document Server

    Zhou, Xiaoyan; Pang, Wei; Zhang, Hao; Yang, Qingrui; Zhang, Daihua

    2013-01-01

    Electromagnetically induced transparency (EIT) and EIT-like effects have been investigated in a wide variety of coupled resonant systems. Here, a classification of the phase characteristics of the EIT-like spectral responses is presented. Newly identified phase responses reveal unexplored operation regimes of EIT-like systems. Taking advantage of the new phase regimes, one can obtain group delay, dispersion and nonlinearity properties greatly enhanced by almost one order of magnitude, compared to the traditionally constructed EIT-like devices, which breaks the fundamental limitation (e.g., delay-bandwidth product) intrinsic to atomic EIT and EIT-like effects. Optical devices and electrical circuits are analyzed as examples showing the universality of our finding. We show that cavity-QED-based quantum phase gates can be greatly improved to achieve a phase shift of {\\pi}. The new phase characteristics are also believed to be useful to build novel doubly resonant devices in quantum information based on cavity QE...

  5. Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y., E-mail: haiyanzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, S.H., E-mail: shzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Cheng, M. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Z.X. [Beijing Institute of Aeronautica1 Materials, Beijing 100095 (China)

    2010-01-15

    The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

  6. Thermophysical properties and behavioral characteristics of phase-change materials

    Energy Technology Data Exchange (ETDEWEB)

    Cantor, S

    1977-01-01

    The primary and near-term objective of the project is to compile a handbook of compounds and mixtures that melt in the range of 90 to 250/sup 0/C and which are suitable for isothermal heat storage. Organic compounds have been screened according to bulk price, thermal stability, and safety. Compounds were selected for further consideration if they cost less than $1.10/kg and if encyclopedia articles or handbooks indicated that they were reasonably stable chemically and were not toxic or otherwise hazardous. Of seven compounds thus selected, four (urea, phthalimide, adipic acid, phthalic anhydride) have been examined by DSC and other methods. The differential scanning calorimeter was used with two fairly well-characterized PCM's to test its applicability for rapidly evaluating thermal decomposition and supercooling. With Na/sub 2/SO/sub 4/ . 10H/sub 2/O, DSC data indicated (a) decrease in heat of transition with thermal cycling, and (b) considerable supercooling; with 3 to 6 percent borax added, supercooling was greatly lessened but not entirely eliminated. Measurements with paraffin wax showed that this material does not supercool nor does it degrade in thermal performance with cycling. The DSC results with these two materials confirmed (and extended) thermal performance characteristics obtained by other means. However, studies of supercooling in urea and in phthalimide suggested that DSC techniques may magnify the extent of supercooling at elevated temperatures.

  7. Study on phase retardation characteristic of LCVR using dispersion analysis and SVM

    Institute of Scientific and Technical Information of China (English)

    HU; Dongmei; LIU; Quan; NIU; Guocheng; ZHU; Yifeng; YU; Lintao

    2015-01-01

    To calibrate the phase retardance of a Liquid crystal variable retarder(LCVR),its birefringence dispersion characteristic was analyzed,and the Support vector machines(SVM) algorithm was adopted to establish the prediction model.The obtained SVM decision function was used as a part of LCVR phase retardance,which was generated by the driving voltage.The experimental verification was carried out with a 568 nm laser.The results show that the deviation of the experimental value and the theoretical value is about 0.0061λ.SVM method could be used as an effective method for LCVR phase retardance characteristic calibration.

  8. Method to measure the phase modulation characteristics of a liquid crystal spatial light modulator.

    Science.gov (United States)

    Wu, Yunlong; Nie, Jinsong; Shao, Li

    2016-11-01

    The universal liquid crystal spatial light modulator (LC-SLM) is widely used in many aspects of optical studies. The working principles and applications of LC-SLM were introduced briefly. The traditional Twyman-Green interference method, which was used to measure the phase modulation characteristics of a liquid spatial light modulator, had some obvious disadvantages in practice. To avoid these issues, the traditional Twyman-Green interference method was improved. Also, a new method to process interference fringes and measure the shift distances and cycles automatically by computers was proposed. The phase modulation characteristics of P512-1064 LC-SLM produced by the Meadowlark Company were measured to verify the validity of the newly proposed method. In addition, in order to compensate and correct the nonlinear characteristics of the phase modulation curve, three universal inverse interpolation methods were utilized. The root mean squared error and residual sum of squares between the calibrated phase modulation curve and the ideal phase modulation curve were reduced obviously by taking advantage of the inverse interpolation methods. Subsequently, the method of shape-preserving subsection cubic interpolation had acquired the best performance with high computation efficiency. Experiments have been performed to verify the validity of the interpolation method. The experimental results showed that the phase modulation characteristics of LC-LSM could be acquired and calibrated automatically with convenience and high efficiency by utilizing the newly proposed processing method.

  9. Numerical investigation on the characteristics of two-phase flow in fuel assemblies with spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.; Yang, Z.; Zhong, Y.; Xiao, Y.; Hu, L. [Chongqing Univ. (China). Key Lab. of Low-grade Energy Utilization Technologies and Systems

    2016-07-15

    In pressurized water reactors (PWRs), the spacer grids of the fuel assembly has significant impact on the thermal-hydraulic performance of the fuel assembly. Particularly, the spacer grids with the mixing vanes can dramatically enhance the secondary flow and have significant effect on the void distribution in the fuel assembly. In this paper, the CFD study has been carried out to analyze the effects of the spacer grid with the steel contacts, dimples and mixing vanes on the boiling two-phase flow characteristics, such as the two-phase flow field, the void distribution, and so on. Considered the influence of the boiling phase change on two-phase flow, a boiling model was proposed and applied in the CFD simulation by using the UDF (User Defined Function) method. Furthermore, in order to analyze the effects of the spacer grid with mixing vanes, the adiabatic (without boiling) two-phase flow has also been investigated as comparison with the boiling two-phase flow in the fuel assembly with spacer grids. The CFD simulation on two-phase flow in the fuel assembly with the proposed boiling model can predict the characteristics of two-phase flow better.

  10. On intermittent flow characteristics of gas–liquid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Thaker, Jignesh; Banerjee, Jyotirmay, E-mail: jbaner@gmail.com

    2016-12-15

    Highlights: • Unified correlations for intermittent flow characteristics are developed. • Influence of inflow conditions on intermittent flow characteristics is analysed. • Developed correlations can be used for effective design of piping components. - Abstract: Flow visualisation experiments are reported for intermittent regime of gas–liquid two-phase flow. Intermittent flow characteristics, which include plug/slug frequency, liquid plug/slug velocity, liquid plug/slug length, and plug/slug bubble length are determined by image processing of flow patterns captured at a rate of 1600 frames per second (FPS). Flow characteristics are established as a function of inlet superficial velocity of both the phases (in terms of Re{sub SL} and Re{sub SG}). The experimental results are first validated with the existing correlations for slug flow available in literature. It is observed that the correlations proposed in literature for slug flow do not accurately predict the flow characteristics in the plug flow regime. The differences are clearly highlighted in this paper. Based on the measured database for both plug and slug flow regime, modified correlations for the intermittent flow regime are proposed. The correlations reported in the present paper, which also include plug flow characteristics will aid immensely to the effective design and optimization of operating conditions for safer operation of two-phase flow piping systems.

  11. Switching Characteristics of Phase Change Memory Cell Integrated with Metal-Oxide Semiconductor Field Effect Transistor

    Institute of Scientific and Technical Information of China (English)

    XU Cheng; CHEN Bomy; LIU Bo; CHEN Yi-Feng; LIANG Shuang; SONG Zhi-Tang; FENG Song-Lin; WAN Xu-Dong; YANG Zuo-Ya; XIE Joseph

    2008-01-01

    A Ge2Sb2Te5 based phase change memory device cell integrated with metal-oxide semiconductor field effect transistor (MOSFET) is fabricated using standard 0.18 μm complementary metal-oxide semiconductor process technology.It shows steady switching characteristics in the dc current-voltage measurement.The phase changing phenomenon from crystalline state to amorphous state with a voltage pulse altitude of 2.0 V and pulse width of 50 ns is also obtained.These results show the feasibility of integrating phase change memory cell with MOSFET.

  12. Characteristics of QCD phase transitions in an extended Skyrme model on S$^{3}$

    CERN Document Server

    Kim, J H; Lee, H K; Kim, Joon Ha; Yee, Sooman; Lee, Hyun Kyu

    1994-01-01

    We study the characteristics of the QCD phase transitions in dense hadronic matter using the Skyrme model constructed on S^3. We find numerically the localized solutions on S^3 using the extended Skyrme model which implements correctly the scale symmetry of QCD. The transition from the localized phase to the delocalized phase is found to be of first order at the critical radius of the hypersphere, L_c. The chiral restoration and the gluon decondensation also take place at the same critical size.

  13. PSYCHOPHYSIOLOGICAL CHARACTERISTICS OF WOMEN IN DEPENDENCE ON THE OVARIOHORMONAL CYCLE PHASE AND PROGESTERONE ACTIVITY (PART 2

    Directory of Open Access Journals (Sweden)

    K. B. Muravlyova

    2013-01-01

    Full Text Available With the aim to identify the effects of menstrual cycle phase on the alpha EEG characteristics the 78 women aged 18–27 years were studied in a within-subject design Half the subjects began investigation at their follicular phase and half at their luteal phase (LP. The alpha peak frequency, alpha band width and power inalpha-2 range are highest, but power in alpha 1 and activation are lowest in LP that is associated with the highest saliva progesterone level.

  14. Phase retrieval for characteristic functions of convex bodies and reconstruction from covariograms

    DEFF Research Database (Denmark)

    Bianchi, Gabriele; Gardner, Richard; Kiderlen, Markus

    2011-01-01

    We propose strongly consistent algorithms for reconstructing the characteristic function $ 1_K$ of an unknown convex body $ K$ in $ \\mathbb{R}^n$ from possibly noisy measurements of the modulus of its Fourier transform $ \\widehat{1_K}$. This represents a complete theoretical solution to the Phase...

  15. Contrast enhancement characteristics of hepatocellular carcinoma on two-phase dynamic scan with spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Dae Young; Choi, Byung Ihn; Han, Joon Koo; Han, Man Chung [College of Medicine, Seoul National University, Seoul (Korea, Republic of)

    1994-12-15

    The purpose of this study was to characterize the enhancing patterns of hepatocellular carcinoma (HCC) on two-phase dynamic incremental liver scan with spiral CT. Two-phase dynamic incremental liver scan using spiral CT was performed on 230 lesions in 107 patients with HCC. CT scanning was performed with a table speed of 13 mm/sec and a section thickness of 10 mm; 120 mL of contrast medium was injected intravenously with a automatic injector at the rate of 3 mL/sec. CT scans were started 35 sec(early phase) and 3 min(delayed phase) after beginning injection of contrast medium. The tumors were divided into 2 groups according to size({<=}3cm and > 3cm), the contrast enhancement patterns of HCCs and capsules in the early and delayed phases were analyzed in each group. Most of HCCs appeared as high-attenuating lesions in the early phase(75% in tumors smaller than 3cm and 61 % in tumors larger than 3cm), and as low-attenuating lesions in the delayed phase(68% in tumors smaller than 3cm and 90% in tumors larger than 3cm). Forty-eight percent of HCCs smaller than 3cm and 58% of HCCs larger than 3 cm were high-attenuating in the early phase and low-attenuating in the delayed phase. Thirty-two percent of capsules were low- or iso-attenuating in the early phase and high-attenuating in the delayed phase. Capsules were demonstrated in 22% in HCCs smaller than 3cm and 67% in HCCs larger than 3 cm (p <. 01). Two-phase dynamic scan with spiral CT is useful in the diagnosis of HCC because of a precise display of hemodynamic characteristics of HCCs.

  16. Local Gas Phase Flow Characteristics of a Gas—Liquid—Solid Three—Phase Reversed Flow Jet Loop Reactor

    Institute of Scientific and Technical Information of China (English)

    WENJianping; ChenYunlin; 等

    2002-01-01

    The local gas-phase flow characteristics such as local gas holdup (εg), local bubble velocity (Vb) and local bubble mean diameter(db) at a specified point in a gas-liquid-solid three-phase reversed flow jet loop reactor was experimentally investigated by a five-point conductivity probe. The effects of gas jet flow rate, liquid jet flow rate, solid loading, nozzle diameter and axial position on the local εg,Vb and db profiles were discussed. The presence of solids at low solid concentrations not only increased the local εg and Vb, but also decreased the local db. The optimum solid olading for the maximum local εg and Vb together with the minimum local db was 0.16×10-3m3, corresponding to a solid volume fraction,εS=2.5%.

  17. Euler Characteristic and Topological Phase Transition of NUT-Kerr-Newman Black Hole

    Institute of Scientific and Technical Information of China (English)

    FAN Hong-Yi; YUE Jing-Hua; YANG Guo-Hong; TIAN Li-Jun; ZHU Shu

    2008-01-01

    From the Causs-Bonnet-Chern theorem, the Euler characteristic of NUT-Kerr-Newman black hole is calculated to be some discrete numbers from 0 to 2. We find that the Bekenstein-Hawking entropy is the largest entropy in topology by taking into account of the relationship between the entropy and the Euler characteristic. The NUT-Kerr-Newman black hole evolves from the torus-like topological structure to the spherical structure with the changes of mass, angular momentum, electric and NUT charges. In this process, the Euler characteristic and the entropy are changed discontinuously, which give the topological aspect of the first-order phase transition of NUT-Kerr-Newman black hole. The corresponding latent heat of the topologicaJ phase transition is also obtained. The estimated latent heat of the black hole evolving from the star just lies in the range of the energy of gamma ray bursts.

  18. Representation of auditory-filter phase characteristics in the cortex of human listeners

    DEFF Research Database (Denmark)

    Rupp, A.; Sieroka, N.; Gutschalk, A.;

    2008-01-01

    , which differently affect the flat envelopes of the Schroeder-phase maskers. We examined the influence of auditory-filter phase characteristics on the neural representation in the auditory cortex by investigating cortical auditory evoked fields ( AEFs). We found that the P1m component exhibited larger...... amplitudes when a long-duration tone was presented in a repeating linearly downward sweeping ( Schroeder positive, or m(+)) masker than in a repeating linearly upward sweeping ( Schroeder negative, or m(-)) masker. We also examined the neural representation of short-duration tone pulses presented...... at different temporal positions within a single period of three maskers differing in their component phases ( m(+), m(-), and sine phase m(0)). The P1m amplitude varied with the position of the tone pulse in the masker and depended strongly on the masker waveform. The neuromagnetic results in all cases were...

  19. Improving Corrosion Resistance of Ferrous Alloy to Molten Zn by Modifying the Laves Phase Characteristics

    Science.gov (United States)

    Liu, X.; Yin, F. C.; Lou, J.; Ouyang, X. M.; Li, Z.

    2017-08-01

    The Laves phase morphology in the Fe25Mo14Cr10Ni1Si (wt.%) alloy was modified by Si addition to improve the corrosion resistance of the ferrous alloy to molten zinc. The Si-containing alloy showed a woven, needle-like Laves phase with higher Mo content than that of the Fe25Mo14Cr10Ni alloy. Corrosion resistance to molten Zn for the Si-containing alloy was more than 20 times higher than that of the silicon-free alloy mainly as a result of the characteristics of the modified Laves phase. This phase was oriented perpendicular to the Zn-diffusion direction, which effectively prevented corrosion by the molten Zn, leading to a denser FeZn13 layer rather than the FeZn10 layer produced in the Fe25Mo14Cr10Ni alloy.

  20. Application analysis of empirical mode decomposition and phase space reconstruction in dam time-varying characteristic

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In view of some courses of the time-varying characteristics processing in the analysis of dam deformation,the paper proposes a new method to analyze the dam time-varying characteristic based on the empirical mode decomposition and phase space reconstruction theory.First of all,to reduce the influences on the traditional statistical model from human factors and assure the analysis accuracy,response variables of the time-varying characteristic are obtained by the way of the empirical mode decomposition;and then,a phase plane of those variables is reconstructed to investigate their processing rules.These methods have already been applied to an actual project and the results showed that data interpretation with the assists of empirical mode decomposition and phase space reconstruction is effective in analyzing the perturbations of response variables,explicit in reflecting the entire development process,and valid for obtaining the evolution rules of the time-varying characteristic.This methodology is a powerful technical support for people to further master the rules of dam operation.

  1. Two-phase flow patterns characteristics analysis based on image and conductance sensors

    Science.gov (United States)

    Wang, Zhenya; Jin, Ningde; Wang, Chun; Wang, Jinxiang

    2008-10-01

    In order to study the temporal and spatial evolution characteristics of gas-liquid two-phase flow pattern, the two-phase flow monitoring system composed of high-speed dynamic camera and Vertical Multi-Electrode Array conductance sensor (VMEA) was utilized to shoot dynamic images and acquire the conductance fluctuating signals of 5 typical vertical gas-liquid two-phase flow patterns in a 125mm i.d. upward pipe. Gray level co-occurrence matrix (GLCM) was used to extract four time-varying characteristic parameter indices which represented different flow image texture structures and also Lempel-Ziv complexity of them were calculated. Then the transition of flow structure and flow property were comprehensively analyzed, combining the result derived from image information with recurrence plots (RPs) and Lempel-Ziv complexity of conductance fluctuating signals. The study showed that the line texture structure of RPs enabled to indicate flow pattern characteristics; the flow image texture structure characteristic parameters sequence described the variance of flow structure and dynamical complexity of different flow patterns.

  2. Heat transfer characteristics of coconut oil as phase change material to room cooling application

    Science.gov (United States)

    Irsyad, M.; Harmen

    2017-03-01

    Thermal comfort in a room is one of human needs in the workplace and dwellings, so that the use of air conditioning system in tropical countries is inevitable. This equipment has an impact on the increase of energy consumption. One method of minimizing the energy use is by using the phase change material (PCM) as thermal energy storage. This material utilizes the temperature difference between day and night for the storage and release of thermal energy. PCM development on application as a material for air cooling inlet, partitioning and interior needs to be supported by the study of heat transfer characteristics when PCM absorbs heat from ambient temperature. This study was conducted to determine the heat transfer characteristics on coconut oil as a phase change material. There are three models of experiments performed in this research. Firstly, an experiment was conducted to analyze the time that was needed by material to phase change by varying the temperature. The second experiment analyzed the heat transfer characteristics of air to PCM naturally convection. The third experiment analyzed the forced convection heat transfer on the surface of the PCM container by varying the air velocity. The data of experimental showed that, increasing ambient air temperature resulted in shorter time for phase change. At temperatures of 30°C, the time for phase change of PCM with the thickness of 8 cm was 1700 min, and it was stable at temperatures of 27°C. Increasing air temperature accelerated the phase change in the material. While for the forced convection heat transfer, PCM could reduce the air temperature in the range of 30 to 35°C at about 1 to 2°C, with a velocity of 1-3 m/s.

  3. Impulsive Control of the Rotor-Stator Rub Based on Phase Characteristic

    Directory of Open Access Journals (Sweden)

    Jieqiong Xu

    2014-01-01

    Full Text Available An impulsive control method is proposed to eliminate the rotor-stator rubbing based on the phase characteristic. The relation between the vibration energy and the phase difference suggests the starting point for controlling the rotor-stator rubbing by implementing impulse. When the contact between the rotor and the stator occurs, the impulse is implemented in x-direction and y-direction several times to avoid the rotor-stator rubbing. The practical feasibility of this approach is investigated by numerical simulations.

  4. Experimental Research on Jerk Characteristics of Tracked Vehicles at Starting Phase

    Institute of Scientific and Technical Information of China (English)

    LIU Hai-ou; CHEN Hui-yan; ZHAI Yong

    2005-01-01

    Based on detailed analysis of vehicle dynamics, the theoretical jerk characteristics of tracked vehicles at starting phase are expressed. The experimental research on jerk characteristics under different control parameters is carried out during main clutch engaging process of AMT vehicles in terms of acceleration measurement. The test results show jerk calculated from acceleration signal is convincing and basically consistent with the subjective feeling of passengers. And the test results have practical value for the objective evaluation and the improvement of starting smoothness of AMT vehicles.

  5. Storage and exchange thermal characteristic analysis of phase change wallboard room with different conditions

    Institute of Scientific and Technical Information of China (English)

    黄凯良; 冯国会; 陈其针; 牛润萍; 刘馨

    2009-01-01

    Based on the phase change material (PCM) thermal characteristic,some testing methods such as differential scanning calorimeter (DSC) etc were used to select the low melting mixture of capric and lauric acid as PCM of phase change wallboard (PCW). The PCW room was established,and some contrast analysis of the storage and exchange thermal characteristic of PCW room and ordinary wall room were made under different conditions. The results show that the fluctuation of indoor air temperature in PCW room is smaller than that in ordinary room obviously. The exchange energy of PCM room with outdoor is less than that of ordinary wall room. In the winter condition,PCW room utilizes valley period electricity to storage energy in the night,while releases at peak period electricity in daytime,which can divert 40% of peak load. In the summer condition,PCW room can reduce the peak cooling load by 25% compared with ordinary wall room.

  6. Dynamic characteristics of two-phase thermal control system for spacecraft

    Science.gov (United States)

    Malozemov, Vladimir V.; Kudryavtseva, Natal'ya S.; Antonov, Viktor A.; Zagar, Oleg V.; Chernobaev, Nikolaj N.

    1992-07-01

    This paper deals with review of the issues associated with modelling the dynamic processes in the spacecraft two-phase thermal control systems. The work presents the results of modelling the nonstationary conditions of the evaporative and condensation heat exchangers functioning, investigates their response to the characteristic external influences. Disclosed are the results of the computer-aided modelling the two-phase thermal control system with a pump. The dynamic characteristics of the change in the inputs of pressures, temperatures and vapor content of a coolant in various branches of the system, as well as the lengths of the heat transfer zones in the evaporator and condenser under effect of the typical disturbing actions are obtained. The attained transients are analyzed.

  7. The characteristic finite difference fractional steps methods for compressible two-phase displacement problem

    Institute of Scientific and Technical Information of China (English)

    袁益让

    1999-01-01

    For compressible two-phase displacement problem, a kind of characteristic finite difference fractional steps schemes is put forward and thick and thin grids are used to form a complete set. Some techniques, such as piecewise biquadratic interpolation, of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estimates in L~2 norm are derived to determine the error in the approximate solution.

  8. Characteristic model based control of the X-34 reusable launch vehicle in its climbing phase

    Institute of Scientific and Technical Information of China (English)

    MENG Bin; WU HongXin; LIN ZongLi; LI Guo

    2009-01-01

    In this paper,a characteristic model based longitudinal control design for the trans-aerosphere vehicle X-34 In its transonic and hypersonic climbing phase is proposed.The design is based on the dynamic characteristics of the vehicle and the curves it is to track in this climbing phase.Through a detailed analysis of the aerodynamics and vehicle dynamics during this climbing phase,an explicit description of the tracking curve for the flight path angle is derived.On the basis of this tracking curve,the tracking curves for the two short-period variables,the angle of attack and the pitch rate,are designed.An all-coefficient adaptive controller is then designed,based on the characteristic modeling,to cause these two short-period variables to follow their respective tracking curves.The proposed design does not require multiple working points,making the design procedure simple.Numerical simulation is performed to validate the performance of the controller.The simulation results Indicate that the resulting control law ensures that the vehicle climbs up successfully under the restrictions on the pitch angle and overloading.

  9. Analysis of the lag phase to exponential growth transition by incorporating inoculum characteristics.

    Science.gov (United States)

    Verhulst, A J; Cappuyns, A M; Van Derlinden, E; Bernaerts, K; Van Impe, J F

    2011-06-01

    During the last decade, individual-based modelling (IbM) has proven to be a valuable tool for modelling and studying microbial dynamics. As each individual is considered as an independent entity with its own characteristics, IbM enables the study of microbial dynamics and the inherent variability and heterogeneity. IbM simulations and (single-cell) experimental research form the basis to unravel individual cell characteristics underlying population dynamics. In this study, the IbM framework MICRODIMS, i.e., MICRObial Dynamics Individual-based Model/Simulator, is used to investigate the system dynamics (with respect to the model and the system modelled). First, the impact of the time resolution on the simulation accuracy is discussed. Second, the effect of the inoculum state and size on emerging individual dynamics, such as individual mass, individual age and individual generation time distribution dynamics, is studied. The distributions of individual characteristics are more informative during the lag phase and the transition to the exponential growth phase than during the exponential phase. The first generation time distributions are strongly influenced by the inoculum state. All inocula with a pronounced heterogeneity, except the inocula starting from a uniform distribution, exhibit commonly observed microbial behaviour, like a more spread first generation time distribution compared to following generations and a fast stabilisation of biomass and age distributions.

  10. Sol-gel composite material characteristics caused by different dielectric constant sol-gel phases

    Science.gov (United States)

    Kimoto, Keisuke; Matsumoto, Makoto; Kaneko, Tsukasa; Kobayashi, Makiko

    2016-07-01

    Ultrasonic transducers prepared by a sol-gel composite method have been investigated in the field of nondestructive testing (NDT). Sol-gel composite materials could be ideal piezoelectric materials for ultrasonic transducer applications in the NDT field, and a new sol-gel composite with desirable characteristics has been developed. Three kinds of sol-gel composite materials composed of different dielectric constant sol-gel phases, Pb(Zr,Ti)O3 (PZT), Bi4Ti3O12 (BiT), and BaTiO3 (BT), and the same piezoelectric powder phase, PbTiO3 (PT), were fabricated and their properties were compared quantitatively. As a result, the PT/BT, sol-gel composite with the highest dielectric constant sol-gel phase showed the highest d 33 and signal strength. In addition, only PT/BT was successfully poled by room-temperature corona poling with reasonable signal strength.

  11. Two-Phase Instability Characteristics of Printed Circuit Steam Generator for the Low Pressure Condition

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han-Ok; Han, Hun Sik; Kim, Young-In; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall manufacturing cost for the components. A PCHE(Printed Circuit Heat Exchanger) is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. PCSG(Printed Circuit Steam Generator) is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. For the introduction of new steam generator, design requirement for the two-phase flow instability should be considered. This paper describes two-phase flow instability characteristics of PCSG for the low pressure condition. PCSG is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. Interconnecting flow path was developed to mitigate the two-phase flow instability in the cold side. The flow characteristics of two-phase flow instability at the PCSG is examined experimentally in this study.

  12. Study Of Phasing Distribution Characteristics Of Reflectarray Antenna Using Different Resonant Elements

    Directory of Open Access Journals (Sweden)

    M.Y. Ismail

    2009-12-01

    Full Text Available There has been much interest recently in developing reflectarray antenna due to the combination of some of the best features between the parabolic reflector and phased array antennas. This paper presents the study of the relationship between phasing distribution characteristics and the bandwidth of different resonant reflectarray elements. The gradient characteristics of different elements of patch, dipole and ring printed on a grounded dielectric substrate have been investigated at X-band frequency range using CST computer model. The preliminary simulated results generated from CST computer model demonstrate that ring elements contribute the highest reflection loss performance of 1.74 dB compared to the other two element of dipoles and patches. The attainable static linear phase range of 177o for ring elements is shown to offer a trade off between the static phase range and the bandwidth of the reflectarray elements. In measurement ring element also contribute the highest reflection loss performance of 2.95 dB compared to other two elements.

  13. Study on Clutter Model and Characteristics of Airborne Radar with Parabolic Conformal Phased Array

    Institute of Scientific and Technical Information of China (English)

    Hao Jiang; Nini Rao; Xingbo Chen; Jiabin Zhou; Chaoyang Qiu; Wen Zhai; Zhimei Hao

    2016-01-01

    The studies on clutter modeling and suppression of airborne radar with a parabolic conformal array are uncommon due to the complexity of this type of antenna array configuration. The correct understanding of clutter characteristics for airborne radar with a parabolic conformal antenna array is the prerequisite and foundation of optimal suppression of this type of clutter. This paper establishes the model of clutter echo of airborne parabolic conformal phased array radar and analyzes the structure characteristics and the distribution features of this type of clutter. The simulation results show that this type of clutter has the following characteristics: 1) The main lobe on the azimuth is seriously broadened, 2) the power spectrum presents strong heterogeneity, and 3) the freedom degrees are high. Based on the existing related clutter suppression methods, we verified the correctness of the constructed clutter model. This work has an important guidance to further study on clutter suppression methods in airborne parabolic conformal array radar.

  14. Characteristics of phase transition and separation in a In-Ge-Sb-Te system

    Science.gov (United States)

    Park, Sung Jin; Jang, Moon Hyung; Park, Seung-Jong; Cho, Mann-Ho; Ko, Dae-Hong

    2012-10-01

    In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge2Sb2Te5 (GST) and In3Sb1Te2 (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point Rs measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point Rs data. In addition, in In28Ge12Sb26Te34, multiple Vth values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In2Te3 occurred in all of the InGeSbTe samples after annealing at 350 °C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge-Te, In-Te, Sb-Te, In-Sb and In-In bond energies.

  15. Sorption characteristics of fluoride on to magnesium oxide-rich phases calcined at different temperatures.

    Science.gov (United States)

    Sasaki, Keiko; Fukumoto, Naoyuki; Moriyama, Sayo; Hirajima, Tsuyoshi

    2011-07-15

    The effect of calcination temperature during production of magnesium oxide-rich phases from MgCO(3) on the sorption of F(-) ions in the aqueous phase has been investigated. Magnesium oxide-rich phases were formed by calcination at over 873 K for 1h. Higher calcination temperatures produced more crystalline MgO with smaller specific surface area and provided larger values of the total basicity per unit surface area. The higher calcination temperatures lead to slower F(-) removal rate, and lower equilibrium F(-) concentrations, when the equilibrium F(-) concentrations are less than 1 mmol dm(-3). Larger total basicity per unit surface area made the reactivity with F(-) ions in aqueous phase more feasible, resulting in a greater degree of F(-) sorption. For equilibrium F(-) concentrations more than 1 mmol dm(-3), lower calcination temperatures favored the co-precipitation of F(-) with Mg(OH)(2), probably leading to the formation of Mg(OH)(2-x)F(x), and the achievement of larger sorption density. This is the first paper which describes the relationship between the solid base characteristics obtained by CO(2)-TPD for MgO with different calcination temperatures as a function of the reactivity of F(-) sorption in the aqueous phase. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Heat Transfer Characteristics of Liquid-Gas Taylor Flows incorporating Microencapsulated Phase Change Materials

    Science.gov (United States)

    Howard, J. A.; Walsh, P. A.

    2014-07-01

    This paper presents an investigation on the heat transfer characteristics associated with liquid-gas Taylor flows in mini channels incorporating microencapsulated phase change materials (MPCM). Taylor flows have been shown to result in heat transfer enhancements due to the fluid recirculation experienced within liquid slugs which is attributable to the alternating liquid slug and gas bubble flow structure. Microencapsulated phase change materials (MPCM) also offer significant potential with increased thermal capacity due to the latent heat required to cause phase change. The primary aim of this work was to examine the overall heat transfer potential associated with combining these two novel liquid cooling technologies. By investigating the local heat transfer characteristics, the augmentation/degradation over single phase liquid cooling was quantified while examining the effects of dimensionless variables, including Reynolds number, liquid slug length and gas void fraction. An experimental test facility was developed which had a heated test section and allowed MPCM-air Taylor flows to be subjected to a constant heat flux boundary condition. Infrared thermography was used to record high resolution experimental wall temperature measurements and determine local heat transfer coefficients from the thermal entrance point. 30.2% mass particle concentration of the MPCM suspension fluid was examined as it provided the maximum latent heat for absorption. Results demonstrate a significant reduction in experimental wall temperatures associated with MPCM-air Taylor flows when compared with the Graetz solution for conventional single phase coolants. Total enhancement in the thermally developed region is observed to be a combination of the individual contributions due to recirculation within the liquid slugs and also absorption of latent heat. Overall, the study highlights the potential heat transfer enhancements that are attainable within heat exchange devices employing MPCM

  17. Experimental study on spray characteristics of alternate jet fuels using Phase Doppler Anemometry

    Science.gov (United States)

    Kannaiyan, Kumaran; Sadr, Reza

    2013-11-01

    Gas-to-Liquid (GTL) fuels have gained global attention due to their cleaner combustion characteristics. The chemical and physical properties of GTL jet fuels are different from conventional jet fuels owing to the difference in their production methodology. It is important to study the spray characteristics of GTL jet fuels as the change of physical properties can affect atomization, mixing, evaporation and combustion process, ultimately affecting emission process. In this work, spray characteristics of two GTL synthetic jet fuels are studied using a pressure-swirl nozzle at different injection pressures and atmospheric ambient condition. Phase Doppler Anemometry (PDA) measurements of droplet size and velocity are compared with those of regular Jet A-1 fuel at several axial and radial locations downstream of the nozzle exit. Experimental results show that although the GTL fuels have different physical properties such as viscosity, density, and surface tension, among each other the resultant change in the spray characteristics is insignificant. Furthermore, the presented results show that GTL fuel spray characteristics exhibit close similarity to those of Jet A-1 fuel. Funded by Qatar Science and Technology Park.

  18. Numerical investigation of refrigeration machine compressor operation considering single-phase electric motor dynamic characteristics

    Science.gov (United States)

    Baidak, Y.; Smyk, V.

    2017-08-01

    Using as the base the differential equations system which was presented in relative units for generalized electric motor of hermetic refrigeration compressor, mathematical model of the software for dynamic performance calculation of refrigeration machine compressors drive low-power asynchronous motors was developed. Performed on its ground calculations of the basic model of two-phase electric motor drive of hermetic compressor and the proposed newly developed model of the motor with single-phase stator winding, which is an alternative to the industrial motor winding, have confirmed the benefits of the motor with innovative stator winding over the base engine. Given calculations of the dynamic characteristics of compressor drive motor have permitted to determine the value of electromagnetic torque swinging for coordinating compressor and motor mechanical characteristics, and for taking them into consideration in choosing compressor elements construction materials. Developed and used in the process of investigation of refrigeration compressor drive asynchronous single-phase motor mathematical and software can be considered as an element of computer-aided design system for design of the aggregate of refrigeration compression unit refrigerating machine.

  19. Characteristics of retention and enthalpies of sorption from the gas phase of esters of trimethylolpropane and C2-C5 acids on DB-1 stationary phase

    Science.gov (United States)

    Krasnykh, E. L.; Aleksandrov, A. Yu.; Sokolova, A. A.; Levanova, S. V.

    2017-02-01

    Characteristics of retention and their temperature dependences, along with the thermodynamic characteristics of sorption on DB-1 nonpolar phase, are determined in the temperature range of 220-280°C for 21 mono-, di-, and trisubstituted esters of trimethylolpropane and monobasic acids with a variety of structures containing from 2 to 6 carbon atoms.

  20. Motivations, enrollment decisions, and socio-demographic characteristics of healthy volunteers in phase 1 research.

    Science.gov (United States)

    Grady, Christine; Bedarida, Gabriella; Sinaii, Ninet; Gregorio, Mark Anthony; Emanuel, Ezekiel J

    2017-08-01

    Phase 1 trials with healthy volunteers are an integral step in drug development. Commentators worry about the possible exploitation of healthy volunteers because they are assumed to be disadvantaged, marginalized, and inappropriately influenced by the offer of money for research for which they do not appreciate the inherent risks. Yet there are limited data to support or refute these concerns. This study aims to describe the socio-demographic characteristics, motivations, and enrollment decision-making of a large cohort of healthy volunteers. We used a cross-sectional anonymous survey of 1194 healthy volunteers considering enrollment in phase 1 studies at Pfizer Clinical Research Units in New Haven, CT; Brussels, Belgium; and Singapore. Descriptive statistics describe motivations and socio-demographic characteristics. Comparisons between groups were examined. The majority rated consideration of risks as more important to their enrollment decision than the amount of money, despite reporting that their primary motivation was financial. Risk, time, money, the competence and friendliness of research staff, and contributing to medical research were important factors influencing enrollment decisions for most participants. The majority of healthy volunteers in this cohort were male, single, reported higher than high school education, and 70% had previous research experience. Many reported low annual incomes (50% below USD$25,000) and high rates of unemployment (33% overall). Nonetheless, risk as an important consideration, money, and other reported considerations and motivations, except for time, did not vary by income, employment, education, or previous experience. There were regional differences in both socio-demographic characteristics and factors important to participation decisions. Healthy volunteers in phase 1 studies consider risks as more important to their enrollment decisions than the amount of money offered, although most are motivated to participate by the

  1. Thermotropic Phase Transition of Benzodithiophene Copolymer Thin Films and Its Impact on Electrical and Photovoltaic Characteristics

    KAUST Repository

    Ko, Sangwon

    2015-02-24

    © 2015 American Chemical Society. We observed a thermotropic phase transition in poly[3,4-dihexyl thiophene-2,2′:5,6′-benzo[1,2-b:4,5-b′]dithiophene] (PDHBDT) thin films accompanied by a transition from a random orientation to an ordered lamellar phase via a nearly hexagonal lattice upon annealing. We demonstrate the effect of temperature-dependent molecular packing on charge carrier mobility (μ) in organic field-effect transistors (OFETs) and photovoltaic characteristics, such as exciton diffusion length (LD) and power conversion efficiency (PCE), in organic solar cells (OSCs) using PDHBDT. The μ was continuously improved with increasing annealing temperature and PDHBDT films annealed at 270 °C resulted in a maximum μ up to 0.46 cm2/(V s) (μavg = 0.22 cm2/(V s)), which is attributed to the well-ordered lamellar structure with a closer - stacking distance of 3.5 Å as shown by grazing incidence-angle X-ray diffraction (GIXD). On the other hand, PDHBDT films with a random molecular orientation are more effective in photovoltaic devices than films with an ordered hexagonal or lamellar phase based on current-voltage characteristics of PDHBDT/C60 bilayer solar cells. This observation corresponds to an enhanced dark current density (JD) and a decreased LD upon annealing. This study provides insight into the dependence of charge transport and photovoltaic characteristics on molecular packing in polymer semiconductors, which is crucial for the management of charge and energy transport in a range of organic optoelectronic devices.

  2. Site Earthquake Characteristics and Dynamic Parameter Test of Phase Ⅲ Qinshan Nuclear Power Engineering

    Institute of Scientific and Technical Information of China (English)

    ZHOV Nian-qing; ZHAO Zai-li; QIN Min

    2009-01-01

    The earthquake characteristics and geological structure of the site to sitting the Qinshan Nuclear Power Station are closely related. According to site investigation drilling, sampling, seismic sound logging wave test in single-hole and cross-hole, laboratory wave velocity test of intact rock, together with analysis of the site geological conditions, the seismic wave test results of the site between strata lithology and the geologic structure were studied. The relationships of seismic waves with the site lithology and the geologic structure were set up.The dynamic parameters of different grades of weathering profile were deduced. The results assist the seismic design of Phase Ⅲ Qinshan Nuclear Power Plant, China.

  3. Model of Three-Limb Three-Phase Transformer Based on Nonlinear Open Circuit Characteristic with Experimental Verification

    Directory of Open Access Journals (Sweden)

    M. Simić

    2014-06-01

    Full Text Available This paper describes the realization of a three-phase transformer model based on a non-linear open-circuit characteristic. The proposed model is based on the fact that in case of a star connection with a neutral wire on the primary windings for all three phases, the applied voltage presents phase voltage and line (phase currents are magnetization currents. These variables are available for measuring and it is easy to obtain three non-linear open circuit characteristics. The results of simulations and a comparison with references and experimental results verified this approach.

  4. The investigations of characteristics of Sb2Te as a base phase-change material

    Science.gov (United States)

    Liu, Guangyu; Wu, Liangcai; Zhu, Min; Song, Zhitang; Rao, Feng; Song, Sannian; Cheng, Yan

    2017-09-01

    Chalcogenide alloys are paid much attention in the study of nonvolatile phase-change memory (PCM). A comprehensive research is investigated on Sb2Te (ST), a base material, from properties to performances in this paper. For the characteristics of ST films, the sheet resistance is extremely stable during cooling process in resistance-temperature measurement and the thickness change of ST film is 5.7%. However, low 10-year data retention temperature (∼55 °C) and large crystal grain are the demerits for ST. In addition, the structure characteristics show stable hexagonal phase and large grain of several hundred nanometers at crystalline state after annealing. As for electrical properties, although the ST-based PCM devices are characterized by fast operation speed of ∼20 ns, only about 8 × 103 times of stable operation cycles can be obtained. After that, the endurance performance deteriorates gradually due to the growth of grains. About resistance drift, the drift coefficients are very small both in crystalline state and in amorphous state.

  5. Characteristics of phase transition and separation in a In-Ge-Sb-Te system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Jin [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Jang, Moon Hyung [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Park, Seung-Jong [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Cho, Mann-Ho, E-mail: mh.cho@yonsei.ac.kr [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Ko, Dae-Hong [Department of Material Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer InGeSbTe films were fabricated via co-deposition stoichiometric GST and IST targets. Black-Right-Pointing-Pointer As the amount of IST was increased in InGeSbTe, the value for V{sub th} and the phase transition temperature were increased. Black-Right-Pointing-Pointer The phase separation in InGeSbTe is caused by differences in the enthalpy change for formation and different atomic concentrations. - Abstract: In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) and In{sub 3}Sb{sub 1}Te{sub 2} (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point R{sub s} measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point R{sub s} data. In addition, in In{sub 28}Ge{sub 12}Sb{sub 26}Te{sub 34}, multiple V{sub th} values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In{sub 2}Te{sub 3} occurred in all of the InGeSbTe samples after annealing at 350 Degree-Sign C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge-Te, In-Te, Sb-Te, In-Sb and In-In bond energies.

  6. Impact of Wettability on Pore-Scale Characteristics of Residual Nonaqueous Phase Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Al-Raoush, Riyadh I.; (Southern)

    2009-07-31

    The objective of this paper was to investigate the impact of wettability of porous media on pore-scale characteristics of residual nonaqueous phase liquids (NAPLs). Synchrotron X-ray microtomography was used to obtain high-resolution three-dimensional images of fractionally wet sand systems with mean grain size of 250 {micro}m. Pore-scale characteristics of NAPL blobs such as volume, lengths, interfacial areas, and sphericity index were computed using three-dimensional image processing algorithms. Four systems comprised of 100, 50, 25, and 0% NAPL-wet mass fractions containing the residual NAPL were imaged and analyzed. Findings indicate that spatial variation in wettability of porous media surfaces has a significant impact on pore-scale characteristics of residual NAPL blobs in saturated porous media systems. As the porous media comprises more water-wet surfaces, residual NAPL blobs increase in size and length due to the entrapment at large pore bodies. NAPL-water interfacial areas tend to increase as the NAPL-wet surface fractions increase in the systems. Overall residual NAPL saturations are less in fractionally wet systems and increase as the systems become more NAPL-wet or water-wet.

  7. Selective Synthesis and Advanced Characteristic of CdSe Semiconductor Quantum Dots by Aqueous Phase

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This work mainly investigated the influences of some factors, such as, synthesis methods, pre cursor alternatives, and vacuum heat-treating process, etc, on the fluorescent characteristics of the semiconductor quantum dots synthesized by aqueous phase.The research results indicate that the fluorescent characteristic of water-solution sample prepared from Na2 SO3 precursor was sensitive to water bath heating time, and specially, its photoluminescence spectrum shows the unique phenomenon of double excitation and emission peaks.Meanwhile,the fluorescent characteristic of water- solution sample prepared from NaBH4 precursor is slightly influenced by water bath heating time, and the surface of CdSe quantum dots could be passivated by the excessive amount of NaBH4precursor, which results in the effective decrease of surface traps and great enhancement of quantum yield.Furthermore, the fluorescent emission peaks of samples could be sharpeued by vacuum heat-treating process, with its spectral full width at half of maximum (FWHM) around 30-40 nm, so the emission peaks become redshift, ofwhich the intensity greatly increases.

  8. Evaluation Of Two Phase Flow Characteristics In A Pipeline Homogenous Model Approach

    Directory of Open Access Journals (Sweden)

    Okoye Obuora A.

    2015-08-01

    Full Text Available The motion of a multi-fluid flow is of interest in the oil and gas industry. The flow characteristics aid or impede production rate. This study analyses two phase fluid flow characteristics consisting of crude oil and natural gas in straight pipes of the same internal diameter using homogenous model. Flow values were obtained from a Niger Delta flow station and predetermined experimental flow equations were used to determine the pressure drop in order to comprehend the flow characteristics in the pipeline. An average total pressure loss amp8710PT of 0.075 MPa was obtained in the laminar flow category at 0.006228 MPam and an average total pressure amp8710PT of 27.896 MPa in turbulent flow category at 2.325 MPam in a pipe length of 12 metres. Graphs were plotted to show the influence of the calculated flow parameters on the fluid flow. The graphs aided in depicting the flow regimes in the pipeline. These are universally dominant parameters in the oil and gas industry as they significantly impact on the transportation of crude oil from oil wells or reservoirs to the process plants. These results may be used as a baseline and guide to compare realistic measurements in similar flows.

  9. Phase-noise characteristics of a 25-GHz-spaced optical frequency comb based on a phase- and intensity-modulated laser.

    Science.gov (United States)

    Ishizawa, Atsushi; Nishikawa, Tadashi; Mizutori, Akira; Takara, Hidehiko; Takada, Atsushi; Sogawa, Tetsuomi; Koga, Masafumi

    2013-12-02

    We investigated phase-noise characteristics of both a phase/intensity-modulated laser with 25-GHz mode spacing and a mode-locked fiber laser with carrier-envelope-offset (CEO) locking. As the separation from the frequency of the continuous wave (CW) laser diode (LD) for a seed light source increases, the integrated phase noise of each comb mode of both the phase/intensity-modulated laser and supercontinuum light originating from it increases with the same slope as a function of mode number. The dependence of the integrated phase noise on mode number with the phase/intensity-modulated laser is much larger than with the mode-locked fiber laser of the CEO locking. However, the phase noise of the phase/intensity-modulated laser is extremely lower than that of the mode-locked fiber laser with CEO locking in the frequency region around the CW LD. The phase noise of the phase/intensity-modulated laser with 25-GHz mode spacing and that of the mode-locked fiber laser with the CEO locking could be estimated and were found to be almost the same at the wavelengths required in an f-to-2f self-referencing interferometer. Our experimental results indicate the possibility of achieving an offset-frequency-locked frequency comb with the phase/intensity-modulated laser.

  10. Environmental mobility of cobalt-Influence of solid phase characteristics and groundwater chemistry.

    Science.gov (United States)

    Payne, T E; Itakura, T; Comarmond, M J; Harrison, J J

    2009-01-01

    The adsorption of cobalt on samples from a potential waste repository site in an arid region was investigated in batch experiments, as a function of various solution phase parameters including the pH and ionic strength. The samples were characterized using a range of techniques, including BET surface area measurements, total clay content and quantitative X-ray diffraction. The statistical relationships between the measured cobalt distribution coefficients (K(d) values) and the solid and liquid phase characteristics were assessed. The sorption of cobalt increased with the pH of the aqueous phase. In experiments with a fixed pH value, the measured K(d) values were strongly correlated to the BET surface area, but not to the amount of individual clay minerals (illite, kaolinite or smectite). A further set of sorption experiments was undertaken with two samples of distinctive mineralogy and surface area, and consequently different sorption properties. A simple surface complexation model (SCM) that conceptualized the surface sites as having equivalent sorption properties to amorphous Fe-oxide was moderately successful in explaining the pH dependence of the sorption data on these samples. Two different methods of quantifying the input parameters for the SCM were assessed. While a full SCM for cobalt sorption on these complex environmental substrates is not yet possible, the basic applicability and predictive capability of this type of modeling is demonstrated. A principal requirement to further develop the modeling approach is adequate models for cobalt sorption on component mineral phases of complex environmental sorbents.

  11. ALMA Long Baseline Campaigns: Phase Characteristics of Atmosphere at Long Baselines in the Millimeter and Submillimeter Wavelengths

    Science.gov (United States)

    Matsushita, Satoki; Asaki, Yoshiharu; Fomalont, Edward B.; Morita, Koh-Ichiro; Barkats, Denis; Hills, Richard E.; Kawabe, Ryohei; Maud, Luke T.; Nikolic, Bojan; Tilanus, Remo P. J.; Vlahakis, Catherine; Whyborn, Nicholas D.

    2017-03-01

    We present millimeter- and submillimeter-wave phase characteristics measured between 2012 and 2014 of Atacama Large Millimeter/submillimeter Array long baseline campaigns. This paper presents the first detailed investigation of the characteristics of phase fluctuation and phase correction methods obtained with baseline lengths up to ∼15 km. The basic phase fluctuation characteristics can be expressed with the spatial structure function (SSF). Most of the SSFs show that the phase fluctuation increases as a function of baseline length, with a power-law slope of ∼0.6. In many cases, we find that the slope becomes shallower (average of ∼0.2–0.3) at baseline lengths longer than ∼1 km, namely showing a turn-over in SSF. These power law slopes do not change with the amount of precipitable water vapor (PWV), but the fitted constants have a weak correlation with PWV, so that the phase fluctuation at a baseline length of 10 km also increases as a function of PWV. The phase correction method using water vapor radiometers (WVRs) works well, especially for the cases where PWV > 1 {mm}, which reduces the degree of phase fluctuations by a factor of two in many cases. However, phase fluctuations still remain after the WVR phase correction, suggesting the existence of other turbulent constituent that cause the phase fluctuation. This is supported by occasional SSFs that do not exhibit any turn-over; these are only seen when the PWV is low (i.e., when the WVR phase correction works less effectively) or after WVR phase correction. This means that the phase fluctuation caused by this turbulent constituent is inherently smaller than that caused by water vapor. Since in these rare cases there is no turn-over in the SSF up to the maximum baseline length of ∼15 km, this turbulent constituent must have scale height of 10 km or more, and thus cannot be water vapor, whose scale height is around 1 km. Based on the characteristics, this large scale height turbulent constituent is

  12. CHARACTERISTICS OF A 4-PHASE VALVE RELUCTANCE MOTOR WHEN POWERED BY UNCAPACITOR SWITCHBOARD

    Directory of Open Access Journals (Sweden)

    V.B. Finkelshtein

    2016-06-01

    Full Text Available Purpose. Nowadays more and more in a variety of machines and mechanisms applied switched reluctance motor. When designing these engines solve the problem selection switch. While the switch scheme comprises symmetrical bridge and eight transistors, eight diodes; Miller switch comprises six transistors and six diodes; in company Graseby Controls Ltd switch circuit but four transistors and four diodes includes two capacitors. The aim is to develop a mathematical model, calculation program, a numerical analysis of the characteristics and parameters of the WFD and the characteristics of their work. Methodology. It is assumed that the resistance in the open state transistors and diodes for direct current is zero and the resistance of the transistors in the closed state, and diode reverse voltage is infinity. When feeding a single-phase motor and power at the same time two adjacent phases determined by the flow through the tooth. Results. The motor powered by a switch on the circuit symmetrical bridge power, which provides a maximum permissible winding temperature is 1.665 kW. But at the same time the surge up to 38.8%, resulting in high levels of noise and vibration. Through the installation of switching angles, ensuring reduction of torque ripple and reduce engine power to a level below which there is a decrease in the value of torque ripple, received power of 1,066 kW and a torque ripple value of 21.18 %. For engines with improved vibration acoustic characteristics necessary to use a switch of four transistors and four diodes. Practical value. For motors with improved vibration acoustic characteristics appropriate to apply uncapacitor switch on four transistors and four diodes, which allows you to receive half the value of torque ripple than the lowest value of the motor torque ripple, eating from a switch on the circuit asymmetric bridge. The cost of reluctance motor with uncapacitor switch on the circuit with four transistors and four diodes is

  13. Flow frictional characteristics of microencapsulated phase change material suspensions flowing through rectangular minichannels

    Institute of Scientific and Technical Information of China (English)

    RAO; Yu; Frank; Dammel; Peter; Stephan; LIN; Guiping

    2006-01-01

    An experimental investigation was conducted on the laminar flow frictional characteristics of suspensions with microencapsulated phase change material (MEPCM) in water flowing through rectangular copper minichannels. The MEPCM was provided at an average particle size of 4.97 μm, and was mixed with distilled water to form suspensions with various mass concentrations ranging from 0 to 20%. The experiment was performed to explore the effect of MEPCM mass concentration on friction factor and pressure drop in the minichannels. The Reynolds number ranged from 200 to 2000 to provide laminar and transitional flows. It was found that the experimental data for the suspensions with 0 and 5% concentration agree well with the existing theoretical data for an incompressible, fully developed, laminar Newtonian flow. For the suspensions with mass concentrations higher than 10%, there is an obvious increase in friction factor and pressure drop in comparison with laminar Newtonian flow.

  14. Measurement of nonlinear coefficient and phase matching characteristics of AgGaS sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Canarelli, P.; Benko, Z.; Hielscher, A.H.; Curl, R.F.; Tittle, F.K. (Dept. of Electrical and Computer Engineering, Rice Quantum Inst., Rice Univ., Houston, TX (US))

    1992-01-01

    This paper reports on a nonlinear optical characteristics of AgGaS{sub 2} that were investigated by measuring visible parametric fluorescence with a pump wavelength of 600 nm. A value of d{sub 36}(AgGaS{sub 2}) = 31 {plus minus} 5 10{sup {minus}12} m/V for the nonlinear coefficient was determined. The temperature dependence of phase matching up to 100{degrees}C was studied. A significant temperature effect, although much smaller than the LiNbO{sub 3}, was found and results in a change in the infrared difference frequency generated of {approximately}0.6 cm{sup {minus}1} {center dot} {degrees}C{sup {minus}1}.

  15. Flow and Heat Transfer Characteristics in a Closed-Type Two-Phase Loop Thermosyphon

    Science.gov (United States)

    Imura, Hideaki; Saito, Yuji; Fujimoto, Hiromitsu

    A closed-loop two-phase thermosyphon can transport a large amount of thermal energy with small temperature differences without any external power supply. A fundamental investigation of flow and heat transfer characteristics was performed experimentally and theoretically using water, ethanol and R113 as the working liquids. Heat transfer coefficients in an evaporator and a condenser, and circulation flow rates were measured experimentally. The effects of liquid fill charge, rotation angle, pressure in the loop and heat flux on the heat transfer coefficients were examined. The heat transfer coefficients in the evaporator and the condenser were correlated by the expressions for pool boiling and film condensation respectively. As a result, the heat transfer coefficients in the evaporator were correlated by the Stephan-Abdelsalam equations within a±40% error. Theoretically, the circulation flow rate was predicted by calculating pressure, temperature, quality and void fraction along the loop. And, the comparison between the calculated and experimental results was made.

  16. Numerical simulation of two-phase flow characteristics in spray drying tower

    Institute of Scientific and Technical Information of China (English)

    ZANG Rende

    2012-01-01

    To optimize the two-phase flow characteristics of flue gas and slurry droplets in spray drying tower,an equalizing plate was installed inside the tower.The Fluent software package,turbulence model and the stochastic model of droplet track were adopted in numerical simulation.Results showed that,the average speed of flue gas along the tower axis was the greatest;the temperature variation in the vicinity of spray nozzle was the largest;when the inlet flue gas speed v was 4 m/s,the temperature gradient variation inside the tower was the maximum,and the slurry droplets full filled the tower; with an increase in the diameter of hole area on equalizing plate,the resistance in tower was gradually decreased,and the viscosity to the wall of slurry droplets first increased and then reduced.

  17. Approximate analytical scattering phase function dependent on microphysical characteristics of dust particles.

    Science.gov (United States)

    Kocifaj, Miroslav

    2011-06-10

    The approximate bulk-scattering phase function of a polydisperse system of dust particles is derived in an analytical form. In the theoretical solution, the particle size distribution is modeled by a modified gamma function that can satisfy various media differing in modal radii. Unlike the frequently applied power law, the modified gamma distribution shows no singularity when the particle radius approaches zero. The approximate scattering phase function is related to the parameters of the size distribution function. This is an important advantage compared to the empirical Henyey-Greenstein (HG) approximation, which is a simple function of the average cosine. However, any optimized value of average cosine of the HG function cannot provide the information on particle microphysical characteristics, such as the size distribution function. In this paper, the mapping between average cosine and the parameters of size distribution function is given by a semianalytical expression that is applicable in rapid numerical simulations on various dust populations. In particular, the modal radius and half-width can be quickly estimated using the presented formulas.

  18. Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode.

    Science.gov (United States)

    Lee, Gyoung-Ja; Kim, Chang Kyu; Lee, Min Ku; Rhee, Chang Kyu

    2010-12-15

    Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode has been investigated using square-wave anodic stripping voltammetry technique, scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy. From the analyses of square-wave anodic stripping voltammograms (SWASV) repetitively measured on the nano-bismuth fixed electrode, it was found that the oxidation peak currents dropped by 81%, 68% and 59% for zinc, cadmium and lead, respectively, after the 100th measurement (about 400 min of operation time). The sphere bismuth nanoparticles gradually changed to the agglomerates with petal shape as the operation time increased. From the analyses of SEM images and XRD patterns, it is confirmed that the oxidation of Bi into BiOCl/Bi(2)O(2)CO(3) and the agglomeration of bismuth nanoparticles caused by the phase change decrease a reproducibility of the stripping voltammetric response. Moreover, most of the bismuth becomes BiOCl at pH 3.0 and bismuth hydroxide, Bi(OH)(3) at pH 7.0, which results in a significant decrease in sensitivity of the nano-bismuth fixed electrode.

  19. Study on the characteristics of novel optical phase array based on waveguide

    Science.gov (United States)

    Li, Li-jing; Ye, Jia-Yu; Chen, Wen

    2016-10-01

    A novel scheme of optical phase array(OPA) based on wave-guide is represented in this paper. Fiber paths is main design of system, the single mode fibers are used as transmission paths, photonic crystal fibers(PCF) are adopted as the output array, LiNbO3 wave-guide is used as the phase modulator. The system configuration have been given in the paper, performance of main device such as LiNbO3 wave-guide and PCF array are analyzed. According to the theory of OPA and electro-optical effect of LiNbO3 wave-guide, the feasibility of system have been demonstrated. By adjusting the phase shift of each LiNbO3 wave-guide, the beam deflection have been observed. Simulation experiments have been implemented to study the influence of its structure parameter on output diffraction characteristics. The results show that the inter-elements distance, the quantity of fiber core and arrangement of fiber core affect the beam steering quality including full width at half-maximum(FWHM), output intensity distribution and normalized amplitude distribution. The grating lobes can be suppressed by smaller distance, the beam scanning accuracy is improved by more units of fiber core. Then two-dimension arrangements of fiber core is analyzed. By adjusting the arrangements of the fiber core, the coupling coefficient and the coupling length between two fiber core in the PCF array are changed, which conduct the different output amplitude distribution. So the structure parameter of PCF array is main factor to the beam steering. With the development of craft for PCF, the research result will provide assistance for the design of OPA in the future.

  20. Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores

    Institute of Scientific and Technical Information of China (English)

    WANG Yunqiang; SHAO Ming'an

    2009-01-01

    The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had a significant effect on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density both reduced oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective way to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good way to improve the accuracy of experimental results. Our results provided information about crude and diesel oils, rather than their components, and may have practical value for remediation of contaminated loessal soils.

  1. Does phase 1 trial enrollment preclude quality end-of-life care? Phase 1 trial enrollment and end-of-life care characteristics in children with cancer.

    Science.gov (United States)

    Levine, Deena R; Johnson, Liza-Marie; Mandrell, Belinda N; Yang, Jie; West, Nancy K; Hinds, Pamela S; Baker, Justin N

    2015-05-01

    End-of-life care (EOLC) discussions and treatment-related decisions, including phase 1 trial enrollment, in patients with incurable disease are complex and can influence the quality of EOLC received. The current study was conducted in pediatric oncology patients to determine whether end-of-life characteristics differed between those who were and were not enrolled in a phase 1 trial. The authors reviewed the medical records of 380 pediatric oncology patients (aged characteristics of these 2 cohorts were compared using regression analysis and chi-square testing. A comparison of patients in the PIC and NPIC revealed no significant differences in either demographic characteristics (including sex, race, religious affiliation, referral origin, diagnosis, or age at diagnosis, with the exception of age at the time of death [P =.03]) or in EOLC indices (such as use or timing of do not attempt resuscitation orders, hospice use or length of stay, forgoing life-sustaining therapies, location of death, time from first EOLC discussion to death, and total number of EOLC discussions). The results of the current study of a large cohort of deceased pediatric cancer patients indicate that enrollment on a phase 1 trial does not affect EOLC characteristics, suggesting that quality EOLC can be delivered regardless of phase 1 trial participation. © 2014 American Cancer Society.

  2. Analysis of the nonlinear dynamic characteristics of two-phase flow based on an improved matrix pencil method☆

    Institute of Scientific and Technical Information of China (English)

    Hongwei Li⁎; Junpeng Liu; Yunlong Zhou; Bin Sun

    2016-01-01

    Gas–liquid two-phase flow is complex and has uncertainty in phase interfaces, which make the two-phase flow look very complicated. Even though the flow behavior (e.g. coalescence, crushing and separation) of single bubble or bubble groups in the liquid phase looks random, combining some established character-istics and methodologies can find regularities among the randomness. In order to excavate the nonlinear dynamic characteristics of gas–liquid two-phase flow, the authors developed an improved matrix pencil (IMP) method to analyze the pressure difference signals of the two-phase flow. This paper elucidates the influence of signal length on MP calculation results and the anti-noise-interference ability of the MP method. An IMP algorithm was applied to the fluctuation signals of gas–liquid two-phase flow to extract the mode frequency and damping ratio, which were combined with the component energy index (CEI) en-tropy to identify the different flow patterns. It is also found that frequency, damping ratio, CEI entropy and stability diagram together not only identify flow patterns, but also provide a new way to examine and un-derstand the evolution mechanism of physical dynamics embedded in flow patterns. Combining these characteristics and methods, the evolution of the nonlinear dynamic physical behavior of gas bubbles is revealed.

  3. [Characteristics of electroosmotic flow in open-tubular capillary electrochromatography with magnetic nanoparticle coating as mixed-mode stationary phase].

    Science.gov (United States)

    Qin, Sasa; Zhou, Chaoran; Zhu, Yaxian; Ren, Zhiyu; Zhang, Lingyi; Fu, Honggang; Zhang, Weibing

    2011-09-01

    A novel open-tubular capillary electrochromatography (OT-CEC) column with magnetic nanoparticle coating as mixed-mode stationary phase was prepared. The mixed-mode stationary phases were obtained by mixing C18 and amino modified magnetic nanoparticles with different ratios. The mixed modified magnetic nanoparticles as stationary phase were introduced into the capillary by using external magnetic force. The magnetic nanoparticle coating can be easily regenerated by removing the external magnetic field, and applied to other separation modes. The characteristics of electroosmotic flow (EOF) were theoretically investigated through the effect of physicochemical properties of different stationary phases on EOF. The experiment was conducted under different ratios of mixed-mode stationary phases and coating lengths, and it was verified that the theoretical conclusions accorded with the experimental results. It was shown that the EOF can be easily adjusted by changing the ratio of stationary phases or the number of permanent magnets.

  4. Characteristics of pressure drop for single-phase and two-phase flow across sudden contraction in microtubes

    Institute of Scientific and Technical Information of China (English)

    LI Zhuo; YU Jian; MA ChongFang

    2008-01-01

    Single-phase and gas-liquid two-phase pressure drops caused by a sudden contraction in microtubes were experimentally investigated at room temperature and atmospheric pressure, using nitrogen and water. The experimental results on pressure drop with a novel measurement method, the tiny gaps on the tubes, were used to characterize the sudden contraction pressure drop for tube diameters from 850 to 330 μm. The ranges of the gas and liquid superficial velocity were 2.55-322.08 and 0.98-9.78 m/s in the smaller tube respectively. In single-phase flow experiments, the contraction loss coefficients were larger than the experimental results from conventional tubes in the laminar flow. While in the turbulent flow, the contraction loss coefficients were slightly smaller than those from conventional tubes and predicted well by Kc=0.5×1-σ2)0.75. In two-phase flow experiments, the slip flow model with a velocity slip ratio S=(ρL/ρG)1/3 showed a good prediction that reveals the occurrence of velocity slip. An empirical correlation for two-phase flow pressure drops caused by the sudden contraction was developed based on the proposed contraction loss coefficients correlation for single-phase flow and Martinelli factor.

  5. Probabilistic physical characteristics of phase transitions at highway bottlenecks: incommensurability of three-phase and two-phase traffic-flow theories.

    Science.gov (United States)

    Kerner, Boris S; Klenov, Sergey L; Schreckenberg, Michael

    2014-05-01

    Physical features of induced phase transitions in a metastable free flow at an on-ramp bottleneck in three-phase and two-phase cellular automaton (CA) traffic-flow models have been revealed. It turns out that at given flow rates at the bottleneck, to induce a moving jam (F → J transition) in the metastable free flow through the application of a time-limited on-ramp inflow impulse, in both two-phase and three-phase CA models the same critical amplitude of the impulse is required. If a smaller impulse than this critical one is applied, neither F → J transition nor other phase transitions can occur in the two-phase CA model. We have found that in contrast with the two-phase CA model, in the three-phase CA model, if the same smaller impulse is applied, then a phase transition from free flow to synchronized flow (F → S transition) can be induced at the bottleneck. This explains why rather than the F → J transition, in the three-phase theory traffic breakdown at a highway bottleneck is governed by an F → S transition, as observed in real measured traffic data. None of two-phase traffic-flow theories incorporates an F → S transition in a metastable free flow at the bottleneck that is the main feature of the three-phase theory. On the one hand, this shows the incommensurability of three-phase and two-phase traffic-flow theories. On the other hand, this clarifies why none of the two-phase traffic-flow theories can explain the set of fundamental empirical features of traffic breakdown at highway bottlenecks.

  6. Amplitude-Phase Characteristics of the Annual Cycle of Surface Air Temperature in the Northern Hemisphere

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The amplitude-phase characteristics (APC) of surface air temperature (SAT) annual cycle (AC)in the Northern Hemisphere are analyzed. From meteorological observations for the 20th century andmeteorological reanalyses for its second half, it is found that over land negative correlation of SAT ACamplitude with annual mean SAT dominates. Nevertheless, some exceptions exist. The positive correlationbetween these two variables is found over the two desert regions: in northern Africa and in Central America.Areas of positive correlations are also found for the northern Pacific and for the tropical Indian and PacificOceans. Southward of the characteristic annual mean snow-ice boundary (SIB) position, the shape ofthe SAT AC becomes more sinusoidal under climate warming. In contrast, northward of it, this shapebecomes less sinusoidal. The latter is also found for the above-mentioned two desert regions. In theFar East (southward of about 50°N), the SAT AC shifts as a whole: here its spring and autumn phasesoccur earlier if the annual mean SAT increases. From energy-balance climate considerations, those trendsfor SAT AC APC in the middle and high latitudes are associated with the influence of the albedo-SATfeedback due to the SIB movement. In the Far East the trends are attributed to the interannual cloudinessvariability, and in the desert regions, to the influence of a further desertification and/or scattering aerosolloading into the atmosphere. In the north Pacific, the exhibited trends could only be explained as aresult of the influence of the greenhouse-gases loading on atmospheric opacity. The trends for SAT ACAPC related to the SIB movement are simulated reasonably well by the climate model of intermediatecomplexity (IAP RAS CM) in the experiment with greenhouse gases atmospheric loading. In contrast,the tendencies resulting from the cloudiness variability are not reproduced by this model. The model alsopartly simulates the tendencies related to the desertification

  7. THE FRICTIONAL RESISTANCE CHARACTERISTICS OF GAS-LIQUID TWO-PHASE FLOW IN HELICAL-COILED TUBES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper deal with the frictional resistance characteristics of gas-liquid two-phase flow in vertical-upward helical-coiled tubes under the system pressure 0.1-0.6MPa.By means of dimension analysis and π theorem, the correlation formulas were obtained for calculating the frictional resistance coefficients of gas-liquid two-phase flow in helical-coiled tubes.The calculated results agree well with the experimental results.

  8. Heat transfer characteristics of titanium/water two-phase closed thermosyphon

    Energy Technology Data Exchange (ETDEWEB)

    Qi Baojin [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang Li [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)], E-mail: lzhang@ecust.edu.cn; Xu Hong; Sun Yan [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2009-09-15

    Experimental investigations were carried out to study heat transfer characteristics of titanium (commercially pure titanium, TA2)/water two-phase closed thermosyphon (Ti/H{sub 2}O TPCT). Experiments of copper/water (Cu/H{sub 2}O) TPCT with same dimension and manufacturing process had also been performed for contrast. Experimental results show that there are no remarkable differences of heat transfer coefficients in evaporator (h{sub e}) between the two kinds of TPCTs, whereas surprisingly the experimental results of heat transfer coefficient in condenser (h{sub c}) of Ti/H{sub 2}O TPCTs are about 2-3 times more than that of Cu/H{sub 2}O TPCTs, moreover the Nusselt's theoretical correlation based on laminar filmwise condensation is not suitable for simulating the h{sub c} of Ti/H{sub 2}O TPCTs. Experimental results and theoretical analysis of surface free energy difference between condensate and solid surface indicate that the mixed condensation mode with dropwise and filmwise condensation coexisting on titanium surface result in the higher h{sub c} for Ti/H{sub 2}O TPCTs. Experiments on condensation mechanism of titanium surface are ongoing to further validate the point.

  9. Heat transfer characteristics of titanium/water two-phase closed thermosyphon

    Energy Technology Data Exchange (ETDEWEB)

    Baojin, Qi; Li, Zhang; Hong, Xu; Yan, Sun [State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China Univ. of Science and Technology, Shanghai 200237 (China)

    2009-09-15

    Experimental investigations were carried out to study heat transfer characteristics of titanium (commercially pure titanium, TA2)/water two-phase closed thermosyphon (Ti/H{sub 2}O TPCT). Experiments of copper/water (Cu/H{sub 2}O) TPCT with same dimension and manufacturing process had also been performed for contrast. Experimental results show that there are no remarkable differences of heat transfer coefficients in evaporator (h{sub e}) between the two kinds of TPCTs, whereas surprisingly the experimental results of heat transfer coefficient in condenser (h{sub c}) of Ti/H{sub 2}O TPCTs are about 2-3 times more than that of Cu/H{sub 2}O TPCTs, moreover the Nusselt's theoretical correlation based on laminar filmwise condensation is not suitable for simulating the h{sub c} of Ti/H{sub 2}O TPCTs. Experimental results and theoretical analysis of surface free energy difference between condensate and solid surface indicate that the mixed condensation mode with dropwise and filmwise condensation coexisting on titanium surface result in the higher h{sub c} for Ti/H{sub 2}O TPCTs. Experiments on condensation mechanism of titanium surface are ongoing to further validate the point. (author)

  10. Investigation of isolated substorms: Generation conditions and characteristics of different phases

    Science.gov (United States)

    Vorobjev, V. G.; Yagodkina, O. I.; Zverev, V. L.

    2016-11-01

    Characteristics of isolated substorms selected by variations in the 1-min values of the AL index are analyzed. The substorms were divided into several types with respect to the behavior of the Bz component of the interplanetary magnetic field (IMF) during the expansion phase. The probability of observations of substorms associated with the northward turn of the Bz component of IMF was 19%, while the substorms taking place at Bz 30 min) period of the southward IMF and a following sharp turn of the Bz component of IMF before the north was detected. The data suggest that a northward IMF turn is neither a necessary nor sufficient condition for generating substorms. It has been shown for substorms of the both types that the average duration of the southward IMF to moment T 0 and the average intensity of the magnetic perturbation in the maximum are approximately the same and amount to 80 min and-650 nT, respectively. However, for substorms at Bz loading-unloading processes in the magnetosphere in the periods of magnetospheric substorms were investigated with different functions that determine the efficiency of the energy transfer from the solar wind to the magnetosphere. It has been shown that the highest correlation coefficient ( r = 0.84) is observed when the function suggested by Newell et al. (2007) is used. It has been detected that a simple function VB S yields a high correlation coefficient ( r = 0.75).

  11. Characteristics of the BDS Carrier Phase Multipath and Its Mitigation Methods in Relative Positioning

    Directory of Open Access Journals (Sweden)

    Wujiao Dai

    2017-04-01

    Full Text Available The carrier phase multipath effect is one of the most significant error sources in the precise positioning of BeiDou Navigation Satellite System (BDS. We analyzed the characteristics of BDS multipath, and found the multipath errors of geostationary earth orbit (GEO satellite signals are systematic, whereas those of inclined geosynchronous orbit (IGSO or medium earth orbit (MEO satellites are both systematic and random. The modified multipath mitigation methods, including sidereal filtering algorithm and multipath hemispherical map (MHM model, were used to improve BDS dynamic deformation monitoring. The results indicate that the sidereal filtering methods can reduce the root mean square (RMS of positioning errors in the east, north and vertical coordinate directions by 15%, 37%, 25% and 18%, 51%, 27% in the coordinate and observation domains, respectively. By contrast, the MHM method can reduce the RMS by 22%, 52% and 27% on average. In addition, the BDS multipath errors in static baseline solutions are a few centimeters in multipath-rich environments, which is different from that of Global Positioning System (GPS multipath. Therefore, we add a parameter representing the GEO multipath error in observation equation to the adjustment model to improve the precision of BDS static baseline solutions. And the results show that the modified model can achieve an average precision improvement of 82%, 54% and 68% in the east, north and up coordinate directions, respectively.

  12. Phase-II conjugation ability for PAH metabolism in amphibians: characteristics and inter-species differences.

    Science.gov (United States)

    Ueda, Haruki; Ikenaka, Yoshinori; Nakayama, Shouta M M; Tanaka-Ueno, Tomoko; Ishizuka, Mayumi

    2011-10-01

    The present study examines amphibian metabolic activity - particularly conjugation - by analysis of pyrene (a four ring, polycyclic aromatic hydrocarbon) metabolites using high-performance liquid chromatography (HPLC) with fluorescence detector (FD), a mass spectrometry detector (MS) system and kinetic analysis of conjugation enzymes. Six amphibian species were exposed to pyrene (dissolved in water): African claw frog (Xenopus laevis); Tago's brown frog (Rana tagoi); Montane brown frog (Rana ornativentris); Wrinkled frog (Rana rugosa); Japanese newt (Cynops pyrrhogaster); and Clouded salamander (Hynobius nebulosus); plus one fish species, medaka (Oryzias latipes); and a fresh water snail (Clithon retropictus), and the resultant metabolites were collected. Identification of pyrene metabolites by HPLC and ion-trap MS system indicated that medaka mainly excreted pyrene-1-glucuronide (PYOG), while pyrene-1-sulfate (PYOS) was the main metabolite in all amphibian species. Pyrene metabolites in amphibians were different from those in invertebrate fresh water snails. Inter-species differences were also observed in pyrene metabolism among amphibians. Metabolite analysis showed that frogs relied more strongly on sulfate conjugation than did Japanese newts and clouded salamanders. Furthermore, urodelan amphibians, newts and salamanders, excreted glucose conjugates of pyrene that were not detected in the anuran amphibians. Kinetic analysis of conjugation by hepatic microsomes and cytosols indicated that differences in excreted metabolites reflected differences in enzymatic activities. Furthermore, pyrenediol (PYDOH) glucoside sulfate was detected in the Japanese newt sample. This novel metabolite has not been reported previously to this report, in which we have identified unique characteristics of amphibians in phase II pyrene metabolism.

  13. Detection of microcalcifications by characteristic magnetic susceptibility effects using MR phase image cross-correlation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Baheza, Richard A. [Department of Biomedical Engineering and Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Welch, E. Brian [Institute of Imaging Science and Departments of Radiology and Radiological Sciences and Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Gochberg, Daniel F. [Institute of Imaging Science and Departments of Radiology and Radiological Sciences, and Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Sanders, Melinda [Department of Pathology, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Harvey, Sara [Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Gore, John C. [Institute of Imaging Science and Departments of Biomedical Engineering, Radiology and Radiological Sciences, Physics and Astronomy, and Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States); Yankeelov, Thomas E., E-mail: thomas.yankeelov@vanderbilt.edu [Institute of Imaging Science and Departments of Radiology and Radiological Sciences, Biomedical Engineering, Physics and Astronomy, and Cancer Biology, Vanderbilt University, Nashville, Tennessee 37232-2310 (United States)

    2015-03-15

    Purpose: To develop and evaluate a new method for detecting calcium deposits using their characteristic magnetic susceptibility effects on magnetic resonance (MR) images at high fields and demonstrate its potential in practice for detecting breast microcalcifications. Methods: Characteristic dipole signatures of calcium deposits were detected in magnetic resonance phase images by computing the cross-correlation between the acquired data and a library of templates containing simulated phase patterns of spherical deposits. The influence of signal-to-noise ratio and various other MR parameters on the results were assessed using simulations and validated experimentally. The method was tested experimentally for detection of calcium fragments within gel phantoms and calcium-like inhomogeneities within chicken tissue at 7 T with optimized MR acquisition parameters. The method was also evaluated for detection of simulated microcalcifications, modeled from biopsy samples of malignant breast cancer, inserted in silico into breast magnetic resonance imaging (MRIs) of healthy subjects at 7 T. For both assessments of calcium fragments in phantoms and biopsy-based simulated microcalcifications in breast MRIs, receiver operator characteristic curve analyses were performed to determine the cross-correlation index cutoff, for achieving optimal sensitivity and specificity, and the area under the curve (AUC), for measuring the method’s performance. Results: The method detected calcium fragments with sizes of 0.14–0.79 mm, 1 mm calcium-like deposits, and simulated microcalcifications with sizes of 0.4–1.0 mm in images with voxel sizes between (0.2 mm){sup 3} and (0.6 mm){sup 3}. In images acquired at 7 T with voxel sizes of (0.2 mm){sup 3}–(0.4 mm){sup 3}, calcium fragments (size 0.3–0.4 mm) were detected with a sensitivity, specificity, and AUC of 78%–90%, 51%–68%, and 0.77%–0.88%, respectively. In images acquired with a human 7 T scanner, acquisition times below 12

  14. First Principles Study of structural characteristics and phase change mechanism of Ge-Sb-Te based materials

    Science.gov (United States)

    Park, Hanjin; Kim, Cheol-Woon; Lee, Hyung-June; Song, Hosin; Kwon, Young-Kyun

    Using ab initio density functional theory, we investigate the structural properties and their phase transition mechanism of the crystalline and amorphous phases of Ge-Sb-Te (GST) based phase change materials, which would be utilized for phase change random access memory. Among various stochiometries of GST, we focus on compositions along the (GeTe)n(Sb2Te3)m pseudo-binary line, denoted simply by (n , m) with integer n and m. We explore various GST materials corresponding (n , m) sets including (1,0), (0,1), (1,1), (2,1) and (1,2) by modeling their both phases. Especially, their amorphous phases can be constructed based on experimental data available or molecular dynamics (MD) simulations performing melt-quench processes. To understand the phase transition mechanism, we evaluate their coordination numbers, radial distribution functions, and angle distribution functions, which enables us to identify the characteristic local geometry representing each phase. We further investigate the thermal properties of various phases by evaluating their phonon densities of states obtained by Fourier-transforming the velocity autocorrelation functions calculated directly from our MD simulation.

  15. Nonlinear current-voltage characteristics due to quantum tunneling of phase slips in superconducting Nb nanowire networks

    Energy Technology Data Exchange (ETDEWEB)

    Trezza, M.; Cirillo, C.; Sabatino, P.; Carapella, G.; Attanasio, C. [CNR-SPIN Salerno and Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, Fisciano I-84084 (Italy); Prischepa, S. L. [Belarusian State University of Informatics and Radioelectronics, P. Browka 6, Minsk 220013 (Belarus)

    2013-12-16

    We report on the transport properties of an array of N∼30 interconnected Nb nanowires, grown by sputtering on robust porous Si substrates. The analyzed system exhibits a broad resistive transition in zero magnetic field, H, and highly nonlinear V(I) characteristics as a function of H, which can be both consistently described by quantum tunneling of phase slips.

  16. Solidification of Liquid Distributed in its Primary Matrix Phase of Al-10Cu-Fe Alloy and Their Tribological Characteristics

    Science.gov (United States)

    Rao, L. Sankara; Jha, A. K.; Ojha, S. N.

    2016-12-01

    Solidification behavior of liquid phase entrained in its primary solid has been investigated. A hypoeutectic alloy based on Al-Cu-Fe system containing Fe and Si was thermal cycled between semisolid regions to low temperatures. The freezing characteristics of the liquid were recorded in inverse rate cooling curves. The continuous network of the liquid phase progressively changed into isolated droplets with their different size and size distribution. Such droplets revealed undercooling of the melt varying from 20 to 35 °C below the eutectic temperature of the alloy. This behavior of melt undercooling is discussed in light of independent nucleation events associated with freezing of droplets. Solidification structure of droplets revealed particulate eutectic phases in contrast to lamellar eutectic microstructure in the interdendritic region of the as-cast alloy. The droplet distribution and their solidification structure resulted in an improvement in tribological characteristics of the alloy. This effect is correlated with features of wear surfaces generated on the matting surfaces.

  17. Research on the filtering characteristic of single phase series hybrid active power filter based on fundamental magnetic flux compensation

    Science.gov (United States)

    Tian, Jun; Chen, Qiaofu; Zhang, Yuqi

    2012-12-01

    In this article, the PWM inverter works as a controlled fundamental current source in the single phase series hybrid active power filter (APF) based on fundamental magnetic flux compensation (FMFC). The series transformer can exhibit the self-impedance of primary winding to harmonic current, which forces harmonic current to flow into passive power filter. With the influence of harmonic current, the voltage of primary winding of transformer is a harmonic voltage, which makes the inverter output currents have a certain harmonic component, and it degrades the filtering characteristics. On the basis of PWM inverter, the mathematical model of series hybrid APF is established, and the filtering characteristics of single phase APF are analysed in detail. Three methods are gained to improve filtering characteristics: reasonably designing the inverter output filter inductance, increasing series transformer ratio and adopting voltage feed-forward control. Experimental results show that the proposed APF has greater validity.

  18. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    Directory of Open Access Journals (Sweden)

    Li Dan

    2015-01-01

    Full Text Available With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-phase frictional pressure drop in the microchannel significantly increases with the decreasing microchannel diameter; Lockhart-Martinelli relationship in divided-phase flow pattern can preferably predict the gas-liquid two-phase frictional pressure drop in the microchannel, but the Tabular constant needs to be corrected.

  19. Damping characteristics of R-phase NiTi shape memory alloys

    Science.gov (United States)

    Wu, Kuang-Hsi; Dalip, S. K.; Liu, Y. Q.; Pu, Zhongjie J.

    1995-05-01

    This paper focuses on the study of damping behavior associated with the R-phase in NiTi shape memory alloy. The variation of the tan((delta) ) and Young's modulus as a function of temperature, ramp rate, frequency, and applied amplitude are systematically studied using a dynamic mechanical analyzer (DMA). It was found that the tan((delta) ) versus the temperature curve exhibits four peaks during the thermal cycle, two peaks each in the heating and in the cooling process. These peaks correspond to the martensite to R-phase, R-phase to austenite, austenite to R-phase, and R-phase to martensite transformations. The value of the tan((delta) ) at each peak is in proportion to the ramp rate and in reverse proportion to frequency. The vibration amplitude tends to have a minor effect on the tan((delta) ). The variation of these peaks with ramp rate, frequency, and amplitude are discussed based on the Delorme and De Jonghe damping model. In addition, the experimental results show that an isotropic softening occurs in the Young's modulus during martensite to R-phase, R-phase to austenite, austenite to R-phase, and R-phase to martensite transformations.

  20. Comparison of analytical protein separation characteristics for three amine-based capillary-channeled polymer (C-CP) stationary phases.

    Science.gov (United States)

    Jiang, Liuwei; Marcus, R Kenneth

    2016-02-01

    Capillary-channeled polymer (C-CP) fiber stationary phases are finding utility in the realms of protein analytics as well as downstream processing. We have recently described the modification of poly(ethylene terephthalate) (PET) C-CP fibers to affect amine-rich phases for the weak anion-exchange (WAX) separation of proteins. Polyethylenimine (PEI) is covalently coupled to the PET surface, with subsequent cross-linking imparted by treatment with 1,4-butanediol diglycidyl ether (BUDGE). These modifications yield vastly improved dynamic binding capacities over the unmodified fibers. We have also previously employed native (unmodified) nylon 6 C-CP fibers as weak anion/cation-exchange (mixed-mode) and hydrophobic interaction chromatography (HIC) phases for protein separations. Polyamide, nylon 6, consists of amide groups along the polymer backbone, with primary amines and carboxylic acid end groups. The analytical separation characteristics of these three amine-based C-CP fiber phases are compared here. Each of the C-CP fiber columns in this study was shown to be able to separate a bovine serum albumin/hemoglobin/lysozyme mixture at high mobile phase linear velocity (∼70 mm s(-1)) but with different elution characteristics. These differences reflect the types of protein-surface interactions that are occurring, based on the active group composition of the fiber surfaces. This study provides important fundamental understanding for the development of surface-modified C-CP fiber columns for protein separation.

  1. Temporal and spatial evolution characteristics of gas-liquid two-phase flow pattern based on image texture spectrum descriptor

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xi-guo; JIN Ning-de; WANG Zhen-ya; ZHANG Wen-yin

    2009-01-01

    The dynamic image information of typical gas-liquid two-phase flow patterns in vertical upward pipe is captured by a high-speed dynamic camera. The texture spectrum descriptor is used to describe the texture characteristics of the processed images whose content is represented in the form of texture spectrum histogram, and four time-varying characteristic param-eter indexes which represent image texture structure of different flow patterns are extracted. The study results show that the amplitude fluctuation of texture characteristic parameter indexes of bubble flow is lowest and shows very random complex dynamic behavior; the amplitude fluctuation of slug flow is higher and shows intermittent motion behavior between gas slug and liquid slug, and the amplitude fluctuation of churn flow is the highest and shows better periodicity; the amplitude fluctuation of bubble-slug flow is from low to high and oscillating frequence is higher than that of slug flow, and includes the features of both slug flow and bubble flow; the slug-churn flow loses the periodicity of slug flow and churn flow, and the amplitude fluctuation is high. The results indicate that the image texture characteristic parameter indexes of different flow pattern can reflect the flow characteristics of gas-liquid two-phase flow, which provides a new approach to tmderstand the temporal and spatial evolution of flow pattern dynamics.

  2. Evaluation of quadrature-phase-shift-keying signal characteristics in W-band radio-over-fiber transmission using direct in-phase/quadrature-phase conversion technique

    Science.gov (United States)

    Suzuki, Meisaku; Kanno, Atsushi; Yamamoto, Naokatsu; Sotobayashi, Hideyuki

    2016-02-01

    The effects of in-phase/quadrature-phase (IQ) imbalances are evaluated with a direct IQ down-converter in the W-band (75-110 GHz). The IQ imbalance of the converter is measured within a range of +/-10 degrees in an intermediate frequency of DC-26.5 GHz. 1-8-G-baud quadrature phase-shift keying (QPSK) signals are transmitted successfully with observed bit error rates within a forward error correction limit of 2×10-3 using radio over fiber (RoF) techniques. The direct down-conversion technique is applicable to next-generation high-speed wireless access communication systems in the millimeter-wave band.

  3. Testing for Nonlinearity in Dynamic Characteristics of Vertical Upward Oil-Gas-Water Three-phase Bubble and Slug Flows

    Institute of Scientific and Technical Information of China (English)

    朱雷; 金宁德; 高忠科; 杜萌; 王振亚

    2012-01-01

    Based on the conductance fluctuation signals measured from vertical upward oil-gas-water three-phase flow experiment, time frequency representation and surrogate data method were used to investigate dynamical characteristics of oil-in-water type bubble and slug flows. The results indicate that oil-in-water type bubble flow will turn to deterministic motion with the increase of oil phase fraction f o and superficial gas velocity U sg under fixed flowrate of oil-water mixture Q mix . The dynamics of oil-in-water type slug flow becomes more complex with the increase of U sg under fixed flowrate of oil-water mixture. The change of f o leads to irregular influence on the dynamics of slug flow. These interesting findings suggest that the surrogate data method can be a faithful tool for characterizing dynamic characteristics of oil-in-water type bubble and slug flows.

  4. Temperature Frequency Characteristics of Hexamethyldisiloxane (HMDSO) Polymer Coated Rayleigh Surface Acoustic Wave (SAW) Resonators for Gas-Phase Sensor Applications

    OpenAIRE

    Ekaterina I. Radeva; Esmeryan, Karekin D.; Avramov, Ivan D.

    2012-01-01

    Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and discusses temperature frequency characteristics (TFCs) of solid hexamethyldisiloxane (HMDSO) polymer coated sensor resonators using the Rayleigh surface acoustic wave (RSAW) mode on ST-cut quartz. Using ...

  5. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    OpenAIRE

    Li Dan

    2015-01-01

    With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-...

  6. BASIC BIOMECHANICAL CHARACTERISTICS OF THE SECOND PHASE (TSUKURI OF JUDO THROWING TECHNIQUE OSOTO GARI

    Directory of Open Access Journals (Sweden)

    Fadil Rexhepi

    2011-09-01

    Full Text Available In a sample of a total of 11 judoists - one was the Tori (thrower, and the other ten were uke (those who were thrown during the performance of throwing technique, was analyzed the second phase of throwing (tsukuri judo technique osoto gari. Tori is an active athlete superior quality (master, body mass = 72 kg, and all the other, who were thrown (uke differ from each other as the weight and height of the body concerned. The average of their body weight was 73.8 kg, which means that it is almost even with body mass of tori. For data collection was used a three-dimensional motion analysis system APAS (Ariel Performance Analysis System. Tsukuri is the phase where occur most actions of reaping leg. The second phase (tsukuri begins when tori detach his right foot and lasts until the beginning of reaping opponent's leg, on which was concentrated its weight (uke's weight. The parameters that describe the effect of the reaping leg in the second phase of technique osoto gari are crucial for the successful execution of this leg technique. For the analysis of the second phase of the throw were selected 14 variables that describe the position of the body and certain body parts of both athletes, velocity parameters of tori's reaping leg and the duration of this phase (time. The role of the tori's standing leg is to maintain a stable position during this phase, while the other leg quickly and in full force acts reaping. The smallest angle of the knee joint of standing leg during the second phase was 130.84 °. Before the moment of reaping, or detachment of uke`s feet from the mat, standing leg has a tendency to extension in the knee joint, which impacts positively on raising the tori's body center of mass. Height tori's body center of mass at the beginning phase was 87.79 cm. As a result of tori's action by pulling onto uke, but little to his left side, the uke`s center of mass at the end of this phase is moved laterally to 6.10 cm. The results show quite

  7. Statistical characteristics of L1 carrier phase observations from four low-cost GPS receivers

    DEFF Research Database (Denmark)

    Cederholm, Jens Peter

    2010-01-01

    Statistical properties of L1 carrier phase observations from four low-cost GPS receivers are investigated through a case study. The observations are collected on a zero baseline with a frequency of 1 Hz and processed with a double difference model. The carrier phase residuals from an ambiguity...... mean value close to zero and the sample variance is time invariant. The residuals from one type of receiver deviate from being normally distributed, whereas the residuals from the remaining receivers are close to being normally distributed. Two of the receivers deliver uncorrelated carrier phase...... observations. Some of the carrier phase observations from the other two receivers are serially correlated. The correlation is receiver specific and is related to the individual channels of the receivers....

  8. Phase Structural Characteristics of ZrV2 Thin Film Prepared by Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Lin; SHI Li-Qun

    2005-01-01

    @@ The thin film metal hydride has become an emerging field of research in metal hydride batteries for its good mechanical and hydrogenation properties. ZrV2 thin films have been prepared using a dc magnetron sputtering method, and the phase structure is investigated. Only amorphous or crystalline Zr and V mixture phases are achieved when substrates are heated during either to 400℃ or to 550 ℃. The annealing causes segregation of Zr and V in the film induced by strain-driven diffusion and interdiffusion between substrate Mo and film elements at high temperature, which results in the formation of mixture phases of C14, C15, Zr and V, but the content of C15 phase is not higher compared with that in the bulk material.

  9. Characteristics of pressure drop for singlephase and two-phase flow across sudden contraction in microtubes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Single-phase and gas-liquid two-phase pressure drops caused by a sudden con-traction in microtubes were experimentally investigated at room temperature and atmospheric pressure,using nitrogen and water. The experimental results on pressure drop with a novel measurement method,the tiny gaps on the tubes,were used to characterize the sudden contraction pressure drop for tube diameters from 850 to 330 μm. The ranges of the gas and liquid superficial velocity were 2.55―322.08 and 0.98―9.78 m/s in the smaller tube respectively. In single-phase flow experiments,the contraction loss coefficients were larger than the experimental results from conventional tubes in the laminar flow. While in the turbulent flow,the contraction loss coefficients were slightly smaller than those from conventional tubes and predicted well by Kc=0.5×(1-σ2)0.75. In two-phase flow experiments,the slip flow model with a velocity slip ratio S=(ρL/ρG)1/3 showed a good prediction that reveals the occurrence of velocity slip. An empirical correlation for two-phase flow pressure drops caused by the sudden contraction was developed based on the proposed contraction loss coefficients correlation for single-phase flow and Mar-tinelli factor.

  10. Effect of inoculation during different phases of agricultural waste composting on spectroscopic characteristics of humic acid

    Institute of Scientific and Technical Information of China (English)

    黄红丽; 曾光明; 罗琳; 张嘉超; 喻曼; 秦普丰

    2015-01-01

    The white-rot fungus, Phanerochaete chrysosporium (P. chrysosporium), was inoculated during different phases of agricultural waste composting and its effect on the spectroscopic characterization of humic acid (HA) was studied. Three runs were used in this study: Run A was the control without inoculating, and Runs B and C were inoculatedP. chrysosporium during the first and the second fermentation phase, respectively. The elemental analysis, ultra-violet spectroscopy (UV), fluorescence spectra, Fourier transform infra-red (FTIR) and13C nuclear magnetic resonance (13C-NMR) of HA all lead to the same conclusion, that is, the degree of aromatization and polymerization of HA increases after 42 days composting. However, the inoculation during different phases presents different effects.P. chrysosporium increases the degree of aromatization and polymerization of HA when it is inoculated during the second fermentation phase, while it does not produce an obvious change on the humification degree of HA when it is inoculated during the first fermentation phase.

  11. Performance characteristics of two-phase-flow turbo-expanders used in water-cooled chillers

    Energy Technology Data Exchange (ETDEWEB)

    Brasz, J.J. [United Technologies Carrier, New York, NY (United States)

    1999-07-01

    Use of two-phase-flow throttle loss recovery devices in water-cooled chillers requires satisfactory part-load operation. This paper describes the results of two-phase-flow impulse turbine testing and the data reduction of the test results into a two-phase-flow turbine off-design performance model. It was found that the main parameter controlling the efficiency of two-phase-flow turbine is the ratio of the nozzle spouting velocity to the rotor speed. The turbine mass flow rate is mainly controlled by inlet subcooling of the entering liquid. The strong sensitivity of turbine mass flow rate on inlet subcooling allows the use of a conventional float valve upstream of the turbine as an effective means of controlling the turbine during part-load operation. For a well-designed two-phase-flow turbine, nozzle spouting velocity and therefore turbine efficiency is hardly affected by the amount of inlet subcooling. Also, capacity can be substantially reduced by a reduction in the amount of inlet subcooling entering the turbine nozzles. Hence, turbine part-load efficiency equals its full-load efficiency over a wide range of flow rates using this control concept. (Author)

  12. Effect of inoculation during different phases of agricultural waste composting on spectroscopic characteristics of humic acid

    Institute of Scientific and Technical Information of China (English)

    黄红丽; 曾光明; 罗琳; 张嘉超; 喻曼; 秦普丰

    2015-01-01

    The white-rot fungus, Phanerochaete chrysosporium(P. chrysosporium), was inoculated during different phases of agricultural waste composting and its effect on the spectroscopic characterization of humic acid(HA) was studied. Three runs were used in this study: Run A was the control without inoculating, and Runs B and C were inoculated P. chrysosporium during the first and the second fermentation phase, respectively. The elemental analysis, ultra-violet spectroscopy(UV), fluorescence spectra, Fourier transform infra-red(FTIR) and 13 C nuclear magnetic resonance(13C-NMR) of HA all lead to the same conclusion, that is, the degree of aromatization and polymerization of HA increases after 42 days composting. However, the inoculation during different phases presents different effects. P. chrysosporium increases the degree of aromatization and polymerization of HA when it is inoculated during the second fermentation phase, while it does not produce an obvious change on the humification degree of HA when it is inoculated during the first fermentation phase.

  13. Numerical investigation of influence on heat transfer characteristics to pneumatically conveyed dense phase flow by selecting models and boundary conditions

    Science.gov (United States)

    Zheng, Y.; Liu, Q.; Li, Y.

    2012-03-01

    Solids moving with a gas stream in a pipeline can be found in many industrial processes, such as power generation, chemical, pharmaceutical, food and commodity transfer processes. A mass flow rate of the solids is important characteristic that is often required to be measured (and controlled) to achieve efficient utilization of energy and raw materials in pneumatic conveying systems. The methods of measuring the mass flow rate of solids in a pneumatic pipeline can be divided into direct and indirect (inferential) measurements. A thermal solids' mass flow-meter, in principle, should ideally provide a direct measurement of solids flow rate, regardless of inhomogeneities in solids' distribution and environmental impacts. One key issue in developing a thermal solids' mass flow-meter is to characterize the heat transfer between the hot pipe wall and the gas-solids dense phase flow. The Eulerian continuum modeling with gas-solid two phases is the most common method for pneumatic transport. To model a gas-solid dense phase flow passing through a heated region, the gas phase is described as a continuous phase and the particles as the second phase. This study aims to describe the heat transfer characteristics between the hot wall and the gas-solids dense phase flow in pneumatic pipelines by modeling a turbulence gas-solid plug passing through the heated region which involves several actual and crucial issues: selections of interphase exchange coefficient, near-wall region functions and different wall surface temperatures. A sensitivity analysis was discussed to identify the influence on the heat transfer characteristics by selecting different interphase exchange coefficient models and different boundary conditions. Simulation results suggest that sensitivity analysis in the choice of models is very significant. The simulation results appear to show that a combination of choosing the Syamlal-O'Brien interphase exchange coefficient model and the standard k-ɛ model along with

  14. Negative DC corona discharge current characteristics in a flowing two-phase (air + suspended smoke particles) fluid

    Science.gov (United States)

    Berendt, Artur; Domaszka, Magdalena; Mizeraczyk, Jerzy

    2017-04-01

    The electrical characteristics of a steady-state negative DC corona discharge in a two-phase fluid (air with suspended cigarette smoke particles) flowing along a chamber with a needle-to-plate electrode arrangement were experimentally investigated. The two-phase flow was transverse in respect to the needle-to-plate axis. The velocity of the transverse two-phase flow was limited to 0.8 m/s, typical of the electrostatic precipitators. We found that three discharge current modes of the negative corona exist in the two-phase (air + smoke particles) fluid: the Trichel pulses mode, the "Trichel pulses superimposed on DC component" mode and the DC component mode, similarly as in the corona discharge in air (a single-phase fluid). The shape of Trichel pulses in the air + suspended particles fluid is similar to that in air. However, the Trichel pulse amplitudes are higher than those in "pure" air while their repetition frequency is lower. As a net consequence of that the averaged corona discharge current in the two-phase fluid is lower than in "pure" air. It was also found that the average discharge current decreases with increasing suspended particle concentration. The calculations showed that the dependence of the average negative corona current (which is a macroscopic corona discharge parameter) on the particle concentration can be explained by the particle-concentration dependencies of the electric charge of Trichel pulse and the repetition frequency of Trichel pulses, both giving a microscopic insight into the electrical phenomena in the negative corona discharge. Our investigations showed also that the average corona discharge current in the two-phase fluid is almost unaffected by the transverse fluid flow up to a velocity of 0.8 m/s. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  15. Hydration Characteristics of Tetracalcium Alumino-Ferrite Phase in the presence Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    M. M. Radwan

    2011-12-01

    Full Text Available Tetracalcium alumino-ferrite phase (C4AF prepared from pure starting materials was employed for composing various mixes prepared of C4AF phase, CaSO4·2H2O, Ca(OH2 and CaCO3. The effect of replacing calcium sulphate (gypsum by calcium carbonate as a set retarder on the hydration behaviour of ferrite phase was studied. The mixes were hydrated for various periods and the hydration products were investigated using the appropriate techniques. The kinetics of hydration was studied by measuring the chemically-combined water as well as the combined lime contents. The mineralogical constitution was studied by using XRD, and DTA. The microstructure of some represented hydrated samples was investigated by scanning electron microscopy. Some interesting conclusions have been drawn. It was found that calcium carbonate reacts with tetracalcium alumino-ferrite phase (C4AF in the presence of hydrolime [Ca(OH2] to form carboferrite compounds which may coat the aluminate grains as ettringite does and this may probably regulate the setting time.

  16. Ensemble and phase averaged flow characteristics in the near wake of a square cylinder

    Science.gov (United States)

    Kim, Kyung Chun; Yoon, Sang Youl; Bok Lee, Man

    2001-11-01

    Ensemble and phase averaged velocity fields in the near wake region behind a square cylinder have been successfully obtained using randomly sampled PIV data sets. The Reynolds numbers based on the flow velocity and the vertex height were 1,600 and 3,900. To identify the phase information, we examined the magnitude of circulation and the center of peak vorticity. The center of vorticity was estimated from lowpass filtered vorticity contours (LES decomposition) adopting a sub-pixel searching algorithm. Due to the sinusoidal nature of circulation which is closely related to the instantaneous vorticity, the location of peak voticity fits well with a sine curve of the circulation magnitude. Conditionally averaged velocity and vorticity fields represent the Karman vortex shedding phenomenon quite successfully within ¡ 3/4 5¡Æ phase uncertainty. The oscillating nature of the separated shear layers and the separation bubble at the upper and lower surfaces are clearly observed. With the hot-wire measurement of Strouhal frequency, we found that the convection velocity changes its magnitude very rapidly from 25 to 75 percent of the free stream velocity along the streamwise direction when the flow passes the recirculation region. Comparison with the circular cylinder wake at the same Reynolds number was made to discuss the difference. Both topology and velocity data associated with a given phase could be useful to verify numerical simulation results by an LES method.

  17. Characteristics and performance of offset phase locked single frequency heterodyned laser systems

    Science.gov (United States)

    Tulchinsky, David A.; Hastings, Alexander S.; Williams, Keith J.

    2016-05-01

    We demonstrate and characterize the performance of two heterodyned optical phase locked loop (PLL) laser systems for use in characterizing photodetector RF frequency response and nonlinearities. Descriptions of PLL circuit parameters for Nd:YAG non-planar ring oscillator lasers at 1064 nm and 1319 nm, and Er ion fiber lasers from 1530 nm to 1565 nm are presented. Both laser systems have piezoelectric transducer wavelength control over the PLL voltage controlled oscillator circuit. Offset frequency phase locking from 1.5 kHz to 51+ GHz is demonstrated. Frequency stability at 10 MHz is measured to be ±50 μHz, limited by the stability of the Rb stabilized crystal oscillator. Phase noise of the phase-locked 1319 nm laser system is discussed where we find that the phase noise is dominated by the input source noise at frequency offsets below 100 Hz and by the laser's RIN noise at frequency offsets > 100 Hz. Comparing nonlinearity data from an InGaAs p-i-n photodiode using both 1319 nm and 1550 nm PLL nonlinearity measurement systems, we find two new separate photodetector nonlinearity mechanisms. Measurements of the harmonic components of a 11 MHz sinusoidal heterodyned optical beat note signal are found to be at or below 1 nW/mW for the second harmonic (at 22 MHz) and at or below 0.25 nW/mW for the 3rd harmonic (at 33 MHz), confirming the nearly pure sinusoidal nature of the optically generated microwave beat note.

  18. Phase transformations and hydrogen-storage characteristics of Mg-transition metal-oxide alloys

    Science.gov (United States)

    Song, Myoung Youp; Baek, Sung Hwan; Bobet, Jean-Loius; Park, Hye Ryoung

    2013-03-01

    Samples with the compositions of 76.5 wt%Mg-23.5 wt%Ni (Mg-Ni), 71.5 wt%Mg-23.5 wt%Ni-5 wt% Fe2O3 (Mg-Ni-Fe2O3) and 71.5 wt%Mg-23.5 wt%Ni-5 wt% Fe2O3 (spray conversion) (Mg-Ni-scFe2O3), 71.5 wt%Mg-23.5 wt%Ni-5 wt% Fe (Mg-Ni-Fe) and 80 wt%Mg-13.33 wt%Ni-6.67 wt%Fe (Mg-13Ni-7Fe) were prepared by reactive mechanical grinding. Mg-13Ni-7Fe has the highest hydriding and dehydriding rates. After hydriding-dehydriding cycling, all the samples contain the Mg2Ni phase. The samples with Fe2O3 and Fe2O3(spray conversion) as starting materials contain the Mg(OH)2 phase after hydriding-dehydriding cycling as well as after reactive mechanical grinding. Mg-Ni-Fe and Mg-13Ni-7Fe contain the MgH2 phase after reactive mechanical grinding. Phases, space groups, cell parameters, contents and crystallite sizes were analyzed by Full Pattern Matching Refinement program, one of the Rietveld analysis programs, from the XRD powder patterns of Mg-Ni-scFe2O3 after reactive mechanical grinding and after hydriding-dehydriding cycling. The MgH2 phase formed in the Mg-Ni-Fe and Mg-13Ni-7Fe mixtures after reactive mechanical grinding is considered to help the pulverization of the materials during reactive mechanical grinding, leading to the high hydriding and dehydriding rates of these mixtures.

  19. Operational characteristics in the three-phase transformer-type SFCL with neutral line based on sequential reclosing process

    Science.gov (United States)

    Cho, Y. S.; Choi, H. S.; Jung, B. I.

    2011-11-01

    In a transformer-type superconducting fault current limiter (SFCL) with a neutral line, which is connected between the superconducting elements and secondary windings, we verified that the SFCL has excellent characteristics that induce the perfect simultaneous quench of the superconducting elements in the previous study. The application of the SFCL to the power networks requires its coordination with the reclosing operation duty, which protects a circuit. In this study, the fault current limiting and recovery characteristics of superconducting elements in the three-phase transformer-type SFCL with the neutral line were analyzed. The limiting rate of the fault current in the transformer-type SFCL could increased by an iron core, which allows quenching of the superconducting elements in a sound phase as well as in a faulted phase. In addition, the simultaneous quench led to uniform burdens on superconducting elements, all of which recovered their superconducting state within an opening cycle of a circuit breaker. Thus, the transformer-type SFCL with the neutral line could reliably conduct the fault current limiting and recovery operations of superconducting elements according to the reclosing operation duty and fault types.

  20. Effect of phase and size characteristics of fly ash from power station on properties of bitumen composites

    Science.gov (United States)

    Lebedev, M. S.; Kozhukhova, N. I.; Chulkova, I. L.

    2017-07-01

    Fly ash from power stations is one of the effective fillers in bitumen binders due to its high specific surface area in origin state. This paper is focused on study of effect of phase and size characteristics of fly ashes on properties of bitumen binder. In this work a high-calcium (FA1) and low-calcium (FA2) fly ashes are used. According to chemical and mineral composition of FA1 is reactive in water medium because it contains hydraulic minerals. FA2 is hydraulically inert mainly consisting of aluminosilicate vitreous phase. FA1 is characterized by higher specific surface vs. FA2 according to Blain method data but lower specific surface measured with BET method. It can be associated with high porosity of FA2 that significantly influent on bitumen content in binding system. Lower packing density of FA2 particles leads to reducing of strength characteristics in bitumen composite. Low adsorption of bitumen to surface of FA1 particles initiates hydration process of reactive minerals as well as formation of ettringite phase that leads to extension of the binder system and structure decompaction. Bitumen composites based on FA2 with higher adsorptive capacity is characterized by more stable structure.

  1. Acoustical characteristics of two-phase horizontal intermittent flow through an orifice

    NARCIS (Netherlands)

    Lee, J.S.; Violato, D.; Polifke, W.

    2016-01-01

    This study addresses acoustical characteristics, in particular, sound generation of intermittent flow regime in a horizontal pipe through an orifice, based on recorded pressure fluctuations and videos of upstream and downstream flow of the orifice. The flow regimes of interest are plug flow and slug

  2. Phase change characteristic study of spherical PCMs in solar energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Veerappan, M.; Kalaiselvam, S.; Iniyan, S. [Refrigeration and Air Conditioning Division, Department of Mechanical Engineering, Anna University, Chennai, Tamil Nadu 600025 (India); Goic, Ranko [Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split (Croatia)

    2009-08-15

    This paper investigates the phase change behavior of 65 mol% capric acid and 35 mol% lauric acid, calcium chloride hexahydrate, n-octadecane, n-hexadecane, and n-eicosane inside spherical enclosures to identify a suitable heat storage material. Analytical models are developed for solidification and melting of sphere with conduction, natural convection, and heat generation. Both the models are validated with previous experimental studies. Good agreement was found between the analytical predictions and experimental study and the deviations were lesser than 20%. Heat flux release at the wall, cumulative energy release to the external fluid, are revealed for the best PCM. The influence of the size of encapsulation, initial temperature of the PCM, the external fluid temperature on solidified and molten mass fraction, and the total phase change time are also investigated. (author)

  3. Cavitation and two-phase flow characteristics of SRPR (Savannah River Plant Reactor) pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    The possible head degradation of the SRPR pumps may be attributable to two independent phenomena, one due to the inception of cavitation and the other due to the two-phase flow phenomena. The head degradation due to the appearance of cavitation on the pump blade is hardly likely in the conventional pressurized water reactor (PWR) since the coolant circulating line is highly pressurized so that the cavitation is difficult to occur even at LOCA (loss of coolant accident) conditions. On the other hand, the suction pressure of SRPR pump is order-of-magnitude smaller than that of PWR so that the cavitation phenomena, may prevail, should LOCA occur, depending on the extent of LOCA condition. In this study, therefore, both cavitation phenomena and two-phase flow phenomena were investigated for the SRPR pump by using various analytical tools and the numerical results are presented herein.

  4. Numerical Analysis of Characteristics of a Particulate Debris Bed Coolability with Single Phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jew-han; Chang, Soon-heung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Cho, Chung-ho; Lee, Yong-bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-05-15

    Designed on the basis of defense-in-depth concept, liquid metal cooled reactor, such as KALIMER-600 is unlikely to undergo the hypothetical core disruptive accident (HCDA). However in case of accident, there exists a possibility of re-criticality and vessel melting when core melt-down occurs. For this reason, the analysis on the ability of post-accident heat removal (PAHR) should be preceded. As a part of this, single phase flow coolability analysis of the particulate debris bed formed at the top of core catcher has been performed to achieve in-vessel fuel retention. The forming process of particulate debris bed is described and single phase cooling model with numerical results are presented.

  5. Combustion Characteristics of Condensed Phase Reactions in Sub-Centimeter Geometries

    Science.gov (United States)

    2012-06-10

    condensed phase reactions Ti/C, Ni/Al, and 3Ni/Al. Several other thermochemical codes ( Cheetah v6.0 [6], NASA CEA [7] and “thermo program” [8]) were...Glaesemann, K.R.; Howard, W.M;, Souers, P.C.; Vitello, P.A. CHEETAH 4.0 User’s Manual, Technical Report for Lawrence Livermore National Laboratory

  6. Phase transformation and structural characteristics of zinc-incorporated β-tricalcium phosphate

    Science.gov (United States)

    Hesaraki, S.; Farhangdoust, S.; Barounian, M. H.

    2013-04-01

    Biological performance of bioceramics such as calcium phosphate has been proved to be improved by substitution of different ions like Mg, Sr and Si. In this study, different amounts of Zn ions in nitrate form were incorporated into β-tricalcium phosphate in which various molar ratios of Ca:Zn were achieved: 3:0, 2.8:0.2, 2.6:0.4, 2.4:0.6, and 2.2:0.8. The mixtures were heated at different temperatures ranging from 800-1100 °C. The phase composition, amount of each phase and lattice parameters of β-tricalcium phosphate were determined by means of X-ray diffractometry and coupled software. Also, solubility of the heated mixtures was investigated by determining the amount of Ca and Zn released into a simulated body fluid during 120 h. The results revealed that only limited amount of Zn ions could be incorporated into β-tricalcium phosphate lattice and ZnO phase was formed when high content of zinc nitrate was introduced in initial mixture. Both a and c lattice parameters of β-tricalcium phosphate were reduced by adding Zn. The release rate of calcium ions into the simulated body fluid was approximately constant during 120 h while for Zn minor release was observed.

  7. Numerical model of characteristics of a particulate debris bed coolability with single phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Je Whan

    2008-02-15

    Designed on the basis of defense-in-depth concept, liquid metal cooled fast reactor, such as KALIMER-600 (Korea Advanced Liquid Metal Reactor) is unlikely to undergo the HCDA (hypothetical core disruptive accident). Because of its inherent safety features, most of the incidents of abnormal operation end with reactor trip and no further progression. Under a postulated, very low probable core meltdown scenario without reactor trip, however, there exists a possibility of re-criticality and vessel melting and the status of debris generated plays an important role. For this reason, the analysis on the ability of post-accident heat removal (PAHR) should be preceded. As a part of this, single phase flow coolability analysis of the particulate debris bed formed at the top of core catcher has been performed to achieve in-vessel fuel retention. The analysis is based on the Ergun equation and Macdonald's work that describe the phenomena of flow through a porous media with Hardee and Nilson's study of temperature relationship of the debris beds. The forming process of particulate debris bed is described and single phase cooling model with numerical results are presented. The analysis was conducted in the condition of three cases, inner and inner+middle and whole core meltdown case. It was proved that the inner and inner+middle core meltdown case could be cooled down with single phase flow. The whole core meltdown case will need some other management. Also, parameter sensitivity test was done.

  8. Characteristic of intermetallic phases in cast dental CoCrMo alloy

    Directory of Open Access Journals (Sweden)

    M. Podrez-Radziszewska

    2010-07-01

    Full Text Available Apart from chromium and molybdenum, casting alloys of cobalt usually contain also up to 0.35 % of carbon. With significant content ofcarbon, presence of carbide-forming alloying elements results in creating carbide phases. These alloys are characterised by dendriticstructure of solid solution of chromium and molybdenum in cobalt with interdendritically precipitated carbides. Because of high chromiumcontent, dominating are M23C6-type carbides, but chromium-rich carbides can be also of M7C3 and M3C2-types. The other elements inthe alloy result in creating M6C and MC-type carbides. In the case of low carbon content, creating carbides and forming intermetallicphases based on the alloying elements and cobalt become limited.The presented research was aimed at characterising structure of the cobalt-based dental alloy containing trace quantity of carbon.Characterised were intermetallic phases hardening the alloy. Microscopic examinations using light microscopy, SEM and TEM werecarried out. Chemical microanalysis of the precipitates using X-ray analyser EDS was performed, as well as phase analysis using selectedarea electron diffraction.

  9. CFD analysis of the two-phase bubbly flow characteristics in helically coiled rectangular and circular tube heat exchangers

    Science.gov (United States)

    Hussain, Alamin; Fsadni, Andrew M.

    2016-03-01

    Due to their ease of manufacture, high heat transfer efficiency and compact design, helically coiled heat exchangers are increasingly being adopted in a number of industries. The higher heat transfer efficiency over straight pipes is due to the secondary flow that develops as a result of the centrifugal force. In spite of the widespread use of helically coiled heat exchangers, and the presence of bubbly two-phase flow in a number of systems, very few studies have investigated the resultant flow characteristics. This paper will therefore present the results of CFD simulations for the two-phase bubbly flow in helically coiled heat exchangers as a function of the volumetric void fraction and the tube cross-section design. The CFD results are compared to the scarce flow visualisation experimental results available in the open literature.

  10. Automated method for the rapid and precise estimation of adherent cell culture characteristics from phase contrast microscopy images.

    Science.gov (United States)

    Jaccard, Nicolas; Griffin, Lewis D; Keser, Ana; Macown, Rhys J; Super, Alexandre; Veraitch, Farlan S; Szita, Nicolas

    2014-03-01

    The quantitative determination of key adherent cell culture characteristics such as confluency, morphology, and cell density is necessary for the evaluation of experimental outcomes and to provide a suitable basis for the establishment of robust cell culture protocols. Automated processing of images acquired using phase contrast microscopy (PCM), an imaging modality widely used for the visual inspection of adherent cell cultures, could enable the non-invasive determination of these characteristics. We present an image-processing approach that accurately detects cellular objects in PCM images through a combination of local contrast thresholding and post hoc correction of halo artifacts. The method was thoroughly validated using a variety of cell lines, microscope models and imaging conditions, demonstrating consistently high segmentation performance in all cases and very short processing times (Source-code for MATLAB and ImageJ is freely available under a permissive open-source license.

  11. A Method to Transit the Rotor-to-Stator Rubbing to Normal Motion Using the Phase Characteristic

    Directory of Open Access Journals (Sweden)

    Jieqiong Xu

    2014-01-01

    Full Text Available A method is proposed to transit the rotor-to-stator rubbing to no-rub motion through active auxiliary bearing. The key point of this technique is to express the attractive domain of no-rub motion based on the phase characteristic and to represent the desired status. The feedback actuation is applied by an active auxiliary bearing to drive the rotor approaching the desired status. After that, the control actuation is turned off. Although the desired status is still in rubbing, it is in the attractive domain of no-rub motion, and the response of the rotor is automatically attracted to no-rub motion.

  12. Characteristics of three-phase internal loop airlift bioreactors with complete gas recirculation for non-Newtonian fluids.

    Science.gov (United States)

    Wen, Jianping; Jia, Xiaoqiang; Cheng, Xianrui; Yang, Peng

    2005-05-01

    Hydrodynamic and gas-liquid mass transfer characteristics, such as liquid velocity, gas holdup, solid holdup and gas-liquid volumetric mass transfer coefficient, in the riser and downcomer of the gas-liquid-solid three-phase internal loop airlift bioreactors with complete gas recirculation for non-Newtonian fluids, were investigated. A mathematical model for the description of flow behavior and gas-liquid mass transfer of these bioreactors was developed. The predicted results of this model agreed well with the experimental data.

  13. Study of the composition and gas-phase release characteristics of salt material extracted from MSW ash particles using STA

    DEFF Research Database (Denmark)

    Arvelakis, Stelios; Frandsen, Flemming; Koukios, E.G.

    2007-01-01

    The ash material generated from the MSW incineration contains large amounts of alkali metals, heavy metals, chlorine and sulfur mainly deposited as inorganic salts and/or oxides on the surface of the Si-rich ash particles. In this work, the composition and gas-phase release characteristics of salt...... material extracted from MSW ash particles using a six-stage leaching process is studied using simultaneous thermal analysis (STA). The produced results provide useful information regarding the composition of the salt material and its melting behavior that is considered to play an important role...

  14. Control of the phase characteristics of Stokes waves in a Michelson interferometer with SBS mirrors

    Science.gov (United States)

    Gordeev, A. A.; Efimkov, V. F.; Zubarev, I. G.; Mikhailov, S. I.

    2016-12-01

    It is found that, when using stimulated Brillouin scattering (SBS) mirrors (mounted in a ring Michelson interferometer) with counterfocusing, under pumping by pulses with steep (2 - 3 {\\text{ns}}) leading edges and applying Freon FC-75 as an active medium, the phase difference of the Stokes waves on the semitransparent interferometer mirror obeys the dependence Δ \\varphi = 2Δ k Δ l (Δ k is the difference in the magnitudes of the pump and Stokes component wave vectors and Δ l is the difference in the optical arm lengths).

  15. Performance characteristics of advanced volume phase holographic gratings for operation in the near infrared

    Science.gov (United States)

    Arns, James A.

    2016-07-01

    Volume phase holographic (VPH) gratings are proven dispersing elements in astronomical spectrographs over the visible spectrum. VPH gratings have also been successfully deployed for use at cryogenic temperatures. Recent advances in production technology now permit the production of gratings for use in the near infrared up to 2450 nm at cryogenic conditions. This paper describes the requirements of VPH gratings for use in the H (wavelengths from 1500 nm to 1800 nm) and K (wavelengths from 1950 nm to 2450 nm) bands, gives the theoretical performances of diffraction efficiency for the production designs and presents the measured performances on the production gratings

  16. Structural, electrical and luminescent characteristics of ultraviolet light emitting structures grown by hydride vapor phase epitaxy

    Directory of Open Access Journals (Sweden)

    A.Y. Polyakov

    2017-03-01

    Full Text Available Electrical and luminescent properties of near-UV light emitting diode structures (LEDs prepared by hydride vapor phase epitaxy (HVPE were studied. Variations in photoluminescence and electroluminescence efficiency observed for LEDs grown under nominally similar conditions could be attributed to the difference in the structural quality (dislocation density, density of dislocations agglomerates of the GaN active layers, to the difference in strain relaxation achieved by growth of AlGaN/AlGaN superlattice and to the presence of current leakage channels in current confining AlGaN layers of the double heterostructure.

  17. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    Science.gov (United States)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  18. Study of mechanical characteristics of window security films by phase-stepping photoelasticity

    Science.gov (United States)

    Stoykova, E.; Van Paepegem, W.; De Pauw, S.; Degrieck, J.; Sainov, V.

    2008-12-01

    The goal of this study is to apply photoelasticity for analysis of the mechanical behavior of thermoplastic polyester window security films. More specifically, the change of the photoelastic pattern for film samples with mechanical stress concentrators (holes and cracks) under tensile load is observed. For the purpose, the samples are covered with photoelastic birefringent PhotoStress® coatings. Being subjected to a tensile external load, the film transfers the strains over its surface to the coating. The latter are observed as interference fringes - isochromatic fringes, which exhibit the difference of the principal strains and isoclinic fringes, which characterize principal strains orientation. The photoelastic measurements were performed with a circular reflection polariscope with a white light and monochromatic illumination (575 nm). In the second case, two-loads phase-shifting technique is used for digital retrieval of isochromatics and isoclinics by successive acquisition of two pairs of four fringe patterns obtained at four different configurations of the optical elements of the polariscope. Since the specifics of the studied thermoplastic materials requires simultaneous recording of the phase-shifted patterns in the non-linear part of their loading curve, we propose an optical arrangement for real-time recording as a future development for solution of non-linear dynamic tasks.

  19. Unusual thermal conduction characteristics of phase change composites with single-walled carbon nanotube inclusion

    Science.gov (United States)

    Harish, Sivasankaran; Ishikawa, Kei; Chiashi, Shohei; Shiomi, Junichiro; Maruyama, Shigeo

    2013-03-01

    Thermal energy storage using phase transition materials is often employed in many engineering applications. However, the low thermal conductivity of such materials inhibits its use for large scale applications. Recently, Zheng et al. [Nature Comm. 2011] demonstrated an efficient technique using graphite suspensions to tune the thermal and electrical conductivity using temperature regulation. In this work, we report large contrasts in thermal conductivity enhancement of nano composites with single walled carbon nanotube (SWCNT) inclusions using first order phase transition process. SWCNTs synthesized by alcohol CVD were dispersed in n-octadecane by tip-sonication with sodium deoxycholate as the surfactant. Thermal conductivity measurements were carried out with transient hot-wire system [Mater. Express 2012]. Thermal conductivity enhancement in the liquid state was found to be nominal and is consistent with the predictions of Maxwell- Garnett type effective medium theory. However, in the frozen state nearly a 2.5 fold increase in thermal conductivity was observed. Similar temperature dependent thermal conductivity contrast was observed when exfoliated graphite nanoplatelets were used as the inclusions. Financial support from Grant-in-Aid for Scientific Research (22226006 and 19054003), Monbukagakusho Scholarship, Global Center of Excellence for Mechanical Systems Innovation

  20. Characteristics of two-phase flow pattern transitions and pressure drop of five refrigerants in horizontal circular small tubes

    Energy Technology Data Exchange (ETDEWEB)

    Pamitran, A.S. [Department of Mechanical Engineering, University of Indonesia, Kampus Baru UI, Depok 16424 (Indonesia); Choi, Kwang-Il [Graduate School, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749 (Korea); Oh, Jong-Taek [Department of Refrigeration and Air Conditioning Engineering, Chonnam National University, San 96-1, Dunduk-Dong, Yeosu, Chonnam 550-749 (Korea); Hrnjak, Pega [Department of Mechanical Science and Engineering, ACRC, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States)

    2010-05-15

    An experimental investigation on the characteristics of two-phase flow pattern transitions and pressure drop of R-22, R-134a, R-410A, R-290 and R-744 in horizontal small stainless steel tubes of 0.5, 1.5 and 3.0 mm inner diameters is presented. Experimental data were obtained over a heat flux range of 5-40 kW/m{sup 2}, mass flux range of 50-600 kg/(m{sup 2} s), saturation temperature range of 0-15 C, and quality up to 1.0. Experimental data were evaluated with Wang et al. and Wojtan et al. [Wang, C.C., Chiang, C.S., Lu, D.C., 1997. Visual observation of two-phase flow pattern of R-22, R-134a, and R-407C in a 6.5-mm smooth tube. Exp. Therm. Fluid Sci. 15, 395-405; Wojtan, L., Ursenbacher, T., Thome, J.R., 2005. Investigation of flow boiling in horizontal tubes: part I - a new diabatic two-phase flow pattern map. Int. J. Heat Mass Transfer 48, 2955-2969.] flow pattern maps. The effects of mass flux, heat flux, saturation temperature and inner tube diameter on the pressure drop of the working refrigerants are reported. The experimental pressure drop was compared with the predictions from some existing correlations. A new two-phase pressure drop model that is based on a superposition model for two-phase flow boiling of refrigerants in small tubes is presented. (author)

  1. Thermal characteristics of non-edible oils as phase change materials candidate to application of air conditioning chilled water system

    Science.gov (United States)

    Irsyad, M.; Indartono, Y. S.; Suwono, A.; Pasek, A. D.

    2015-09-01

    The addition of phase change material in the secondary refrigerant has been able to reduce the energy consumption of air conditioning systems in chilled water system. This material has a high thermal density because its energy is stored as latent heat. Based on material melting and freezing point, there are several non-edible oils that can be studied as a phase change material candidate for the application of chilled water systems. Forests and plantations in Indonesia have great potential to produce non-edible oil derived from the seeds of the plant, such as; Calophyllum inophyllum, Jatropha curcas L, and Hevea braziliensis. Based on the melting temperature, these oils can further studied to be used as material mixing in the secondary refrigerant. Thermal characteristics are obtained from the testing of T-history, Differential Scanning Calorimetric (DSC) and thermal conductivity materials. Test results showed an increase in the value of the latent heat when mixed with water with the addition of surfactant. Thermal characteristics of each material of the test results are shown completely in discussion section of this article.

  2. Phase-transition and aggregation characteristics of a thermoresponsive dextran derivative in aqueous solutions.

    Science.gov (United States)

    Shi, Huan-Ying; Zhang, Li-Ming

    2006-10-16

    Grafting of poly(N-vinylcaprolactam) side chains onto a hydrophilic dextran backbone was found to provide the dextran with new, thermoresponsive properties in aqueous solutions. Depending on its solution concentration, the resulting dextran derivative could exhibit a temperature-induced phase-transition and critical transition temperature (T(c)). Different anions and cations of added salts, including five potassium salts and five alkali-metal chlorides, were observed to influence the T(c) value of its aqueous solution. Except for potassium iodide, all added salts were found to lower the T(c) value. The addition of the surfactant, cationic cetyltrimethylammonium bromide or anionic sodium dodecyl sulfate, resulted in an increase of the T(c) value. With the help of the Coomassie Brilliant Blue dye as a polarity probe, the formation of hydrophobic aggregates above the T(c) was revealed for this new dextran derivative in aqueous solution.

  3. A study of characteristics of intercity transportation systems. Phase 1: Definition of transportation comparison methodology

    Science.gov (United States)

    English, J. M.; Smith, J. L.; Lifson, M. W.

    1978-01-01

    Decision making in early transportation planning must be responsive to complex value systems representing various policies and objectives. The assessment of alternative transportation concepts during the early initial phases of the system life cycle, when supportive research and technology development activities are defined, requires estimates of transportation, environmental, and socio-economic impacts throughout the system life cycle, which is a period of some 40 or 50 years. A unified methodological framework for comparing intercity passenger and freight transportation systems is described and is extended to include the comparison of long term transportation trends arising from implementation of the various R & D programs. The attributes of existing and future transportation systems are reviewed in order to establish measures for comparison, define value functions, and attribute weightings needed for comparing alternative policy actions for furthering transportation goals. Comparison criteria definitions and an illustrative example are included.

  4. Phase-amplitude coupling characteristics in directly modulated quantum dot lasers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C. [Télécom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 75634 Paris Cedex 13 (France); Institut National des Sciences Appliquées, Université Européenne de Bretagne, 35708 Rennes Cedex 7 (France); Osiński, M. [Télécom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 75634 Paris Cedex 13 (France); Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106-4343 (United States); Even, J. [Institut National des Sciences Appliquées, Université Européenne de Bretagne, 35708 Rennes Cedex 7 (France); Grillot, F. [Télécom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 75634 Paris Cedex 13 (France)

    2014-12-01

    We present a semi-analytical model for studying the phase-amplitude coupling (α-factor) in quantum dot (QD) semiconductor lasers, which takes into account the influence of carrier populations in the excited state and in the two-dimensional carrier reservoir on the refractive index change. Calculations of the α-factor based on the amplified spontaneous emission method and on the “FM/AM” technique are both investigated. It is shown that the α-factor of a QD laser strongly depends on the energy separation between the ground state and the off-resonant states. Through band structure engineering, the α-factor can be reduced by enlarging this energy separation.

  5. On flow characteristics of liquid-solid mixed-phase nanofluid inside nanochannels

    Institute of Scientific and Technical Information of China (English)

    H AMINFAR; N RAZMARA; M MOHAMMADPOURFARD

    2014-01-01

    The atomic behavior of liquid-solid mixed-phase nanofluid flows inside nanochannels is investigated by a molecular dynamics simulation (MDS). The results of visual observation and statistic analysis show that when the nanoparticles reach near each other, the strong interatomic force will make them attach together. This aggrega-tion continues until all nanoparticles make a continuous cluster. The effect of altering the external force magnitude causes changes in the agglomeration rate and system enthalpy. The density and velocity profiles are shown for two systems, i.e., argon (Ar)-copper (Cu) nanofluid and simple Ar fluid between two Cu walls. The results show that using nanopar-ticles changes the base fluid particles ordering along the nanochannel and increases the velocity. Moreover, using nanoparticles in simple fluids can increase the slip length and push the near-wall fluid particles into the main flow in the middle of the nanochannel.

  6. Fluctuant characteristics of two-phase flow behind a bottom aerator

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Experimental observations show that the random process of two-phase flow behind an aerator is an ergodic process and its amplitude distribution is similar to a normal distribution. The maximum pressure fluctuation is at the re-attachment point where the jet-trajectory flow over the aerator re-attaches to the bottom of the channel, and its amplitude is 2—3 times larger than when there is no aerator. There is a dominant frequency of 1.24 Hz in the model, but the coherence in the frequency domain is not obvious for other frequencies beside the dominant frequency. There is a large vortex at the re-attachment point behind the aerator but correlation among the measurement points is not obvious in the time domain.

  7. Leaching characteristics of poultry litter in first phase of multistage anaerobic digestion

    Directory of Open Access Journals (Sweden)

    Surya P Sunkavalli

    2014-05-01

    Full Text Available Poultry litter is highly biodegradable in nature. Therefore, it could be subjected to biomethanation to produce valuable biogas and bio-manure as byproducts. Some studies have been conducted along these lines in India by utilizing the poultry litter as a substrate in batch type dung digesters of KVIC and DENABANDHU models. However, these reactors have the drawbacks of high residence time (30 – 35 days, scum formation problems etc. Moreover, these batch type plants are not suitable for the treatment of large quantities of solid waste. Multistage anaerobic digestion has the potential to overcome some of the aforesaid issues. Anaerobic leaching experiments were conducted at different total solids concentration and pH using poultry litter in order to evaluate the leachate quality for a period of 7 days. The increase in Total solids (TS % from 15 to 20% show inverse effect on VFA and Alkalinity. The change in pH from 8.5 to 5.5 didn’t show much impact on VFA but there is a small impact on alkalinity. It was also observed that the leaching of the organic matter in the solid to the liquid phase is very fast and it is taking place approximately in three to four days and subsequently leachate getting saturated. Therefore, reactor set up was made in the last phase to regularly remove the water from the reactor so that higher driving force is available for leaching. The study resulted in leaching of maximum organic content in the solid to liquid within three days. DOI: http://dx.doi.org/10.3126/ije.v3i2.10516 International Journal of the Environment Vol.3(2 2014: 76-82

  8. Energetic and exploitation characteristics of a two-phase ejecting vacuum system built in the paper machine at A.D. Komuna Skopje

    Directory of Open Access Journals (Sweden)

    Šarevski Milan

    2004-01-01

    Full Text Available This work presents the concept of a two-phase ejecting vacuum system. The energetic characteristics of these systems were analyzed and compared to those with mechanical pumps with water ring and turbo compressor vacuum pumps. A method for optimizing a two-phase thermo compressor vacuum systems is presented. The analysis included the exploitation characteristics of the system developed at A.D. "Komuna" Skopje.

  9. Analysis of time phase of characteristic rad iation in plasma induced by laser ablating aluminum

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With time- and space-resolved technique, we have recorde d time-resolved spectra of irradiation of the plasma induced by Nd: YAG laser a blating metal Aluminum in Ar, in which, laser pulse-energy was set up to 145 mJ /pulse and the buffer pressure 100 kpa. The continuum radiation and special emis sion of Aluminum plasma were studied based on the records. According to time dis tribution of Al Ⅰ396.15 nm emission, we analyzed the time differences between c haracteristic and continuum radiation evolving. We tried to explain the time pha ses of characteristic radiation evolving with traditional theoretical model of a tomic transition. As the result, we found that it was difficult to explain our e xperimental results with the model. In order to explain our experimental results , we need new model or to improve the traditional theoretical model of atomic tr ansition.

  10. Two-phase flow characteristics across sudden expansion in small rectangular channels

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ing Youn [Mechanical Engineering Department, National Yunlin University of Science and Technology, Yunlin 640 (China); Liu, Chung-Che; Chien, Kuo-Hsiang; Wang, Chi-Chuan [D100, Energy and Environment Research Laboratories, Industrial Technology Research Institute, Bldg. 64, 195-6 Section 4, Chung Hsing Road, Chutung, Hsinchu 310 (China)

    2007-11-15

    This study examines the two-phase flow pattern change and frictional pressure loss pertaining to the sudden flow area expansion from a small diameter tube into small rectangular channels. It is found that a unique flow pattern ''liquid jet-like flow pattern'' occurs at a very low quality region of G=100kg/ m{sup 2} s in a test section of 3mm x 9mm. This flow pattern is almost inconceivable for the 3mm x 6mm test section. The pressure difference usually increases with vapor quality but a setback is encountered provided that the liquid jet flow pattern prevails. A phenomenal observation suggests that a conceivable reduction of the pressure difference is related to the liquid jet-like flow pattern, yet a flat or level-off of the pressure difference is seen when the liquid jet-like flow is less pronounced. By contrast, an appreciable increase of pressure difference is seen when the liquid jet-like flow pattern is completely gone. The measured pressure differences are compared with existing correlations/models, whereas none of them gives satisfactory predictions against the present data. It is found that a slight modification to the empirical constant K of Wadle's correlation may give rise to a fair improvement of the predictive ability. (author)

  11. Droplet phase characteristics in liquid-dominated steam--water nozzle flow

    Energy Technology Data Exchange (ETDEWEB)

    Alger, T.W.

    1978-08-09

    An experimental study was undertaken to determine the droplet size distribution, the droplet spatial distribution and the mean droplet velocity in low-quality, steam-water flow from a rectangular cross-section, converging-diverging nozzle. A unique forward light scattering technique was developed for droplet size distribution measurements. Droplet spatial variations were investigated using light transmission measurements, and droplet velocities were measured with a laser-Doppler velocimeter (LDV) system incorporating a confocal Fabry-Perot interferometer. Nozzle throat radius of curvature and height were varied to investigte their effects on droplet size. Droplet size distribution measurements yielded a nominal Sauter mean droplet diameter of 1.7 ..mu..m and a nominal mass-mean droplet diameter of 2.4 ..mu..m. Neither the throat radius of curvature nor the throat height were found to have a significant effect upon the nozzle exit droplet size. The light transmission and LDV measurement results confirmed both the droplet size measurements and demonstrated high spatial uniformity of the droplet phase within the nozzle jet flow. One-dimensional numerical calculations indicated that both the dynamic breakup (thermal equilibrium based on a critical Weber number of 6.0) and the boiling breakup (thermal nonequilibrium based on average droplet temperature) models predicted droplet diameters on the order of 7.5 ..mu..m, which are approximately equal to the maximum stable droplet diameters within the nozzle jet flow.

  12. Two-phase flow characteristics during flow boiling of halocarbon refrigerants in micro-scale channels

    Energy Technology Data Exchange (ETDEWEB)

    Arcanjo, Alexandre A.; Freitas, Juliano O.; Tibirica, Cristiano B.; Ribatski, Gherhardt [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Escola de Engenharia. Dept. de Engenharia Mecanica

    2009-07-01

    Quasi-diabatic two-flow pattern visualizations and measurements of elongated bubble velocity, frequency and length were performed. The tests were run for R134a evaporating in a stainless steel tube with diameter of 2.32 mm, mass velocities from 50 to 600 kg/m{sup 2}s and saturation temperatures of 22 deg C, 31 deg C and 41 deg C. The tube was heated by applying a direct DC current to its surface. Images from a high-speed video-camera (8000 frames/s) obtained through a transparent tube just downstream of the heated section were used to identify the following flow patterns: bubbly, elongated bubbles, churn and annular. Dryout conditions were also characterized. Local heat transfer results were considered when investigating the presence of stratified flows. The visualized flow patterns were compared against the predictions provided by Barnea et al., Felcar et al. and Revellin and Thome. For the present database, the method recently proposed by Felcar et al. provides the best predictions. Additionally, elongated bubble velocities, frequencies and lengths were determined based on an analysis of high speed videos. Results suggested that the elongated bubble velocity depends on mass velocity, vapor quality and saturation temperature, and is independent of bubble length. The bubble velocity increases with increasing mass velocity and vapor quality and decreases with increasing saturation temperature. Additionally, bubble velocity was correlated as a linear function of the two-phase superficial velocity. (author)

  13. Performance characteristics of two volume phase holographic grisms produced for the ESPRESSO spectrograph

    Science.gov (United States)

    Arns, James A.

    2016-08-01

    The ESPRESSO spectrograph [1], a new addition to the European Southern Observatory's (ESO) Very Large Telescope (VLT), requires two volume phase holographic (VPH) grisms, one blue and the other red, splitting the overall spectral range of the instrument to maximize throughput while achieving high resolution. The blue grism covers the spectral range from 375 nm to 520 nm with a dispersion of 0.88 degrees/nm at the central wavelength of 438 nm. The red grism operates from 535 nm to 780 nm with a dispersion of 0.47 degrees/nm at 654.8 nm. Both designs use a single input prism to enhance the dispersion of the grism assembly. The grisms are relatively large in size with a working aperture of 185 mm x 185 mm for the blue grism and 215 nm x 185 mm for the red grism respectively. This paper describes the specifications of the two grating types, gives the rigorous coupled wave analysis (RCWA) theoretical performances of diffraction efficiency for the production designs and presents the measured performances of each of the delivered grisms.

  14. Incorporating a Patient Dichotomous Characteristic in Cancer Phase I Clinical Trials Using Escalation with Overdose Control

    Directory of Open Access Journals (Sweden)

    Mourad Tighiouart

    2012-01-01

    Full Text Available We describe a design for cancer phase I clinical trials that takes into account patients heterogeneity thought to be related to treatment susceptibility. The goal is to estimate the maximum tolerated dose (MTD given patient’s specific dichotomous covariate value. The design is Bayesian adaptive and is an extension of escalation with overdose control (EWOC. We will assess the performance of this method by comparing the following designs via extensive simulations: (1 design using a covariate; patients are accrued to the trial sequentially and the dose given to a patient depends on his/her baseline covariate value, (2 design ignoring the covariate; patients are accrued to the trial sequentially and the dose given to a patient does not depend on his/her baseline covariate value, and (3 design using separate trials; in each group, patients are accrued to the trial sequentially and EWOC is implemented in each group. These designs are compared with respect to safety of the trial and efficiency of the estimates of the MTDs via extensive simulations. We found that ignoring a significant baseline binary covariate in the model results in a substantial number of patients being overdosed. On the other hand, accounting for a nonsignificant covariate in the model has practically no effect on the safety of the trial and efficiency of the estimates of the MTDs.

  15. Characteristics of Plate-Fin Heat Exchanger with Phase Change Material

    Science.gov (United States)

    Okada, Masashi

    In the present paper, a plate-fin heat exchanger with a phase change material (PCM) was studied. The heat exchanger was a singlepass cross-flow type, where both fluids (air) were unmixed. N-octadecane, of which the fusion temperature is 28.0°C, was used as the PCM. Three kinds of experiments were carried out and the inlet and outlet temperatures and the temperatures in the PCM were measured. In the first experiments, the effectiveness and the overall heat-transfer coefficient were obtained at steady states. By the calculations of steady three-dimensional heat conduction, the effects of the parameters, ---, dimensions, thermal properties, and heat transfer coefficients of air ---, on the overall heat-transfer coefficients were obtaiend clearly. In the second experiments, after the higher-temperature air-flow was stopped, the outlet temperatures of the lower-temperature air were maintained at the constant temperatures for 90-150 minutes. In the third experiments, the higher temperature air was flowed intermittently with an equal interval. The fluctuation of the outlet temperature of the lower-temperature air was within ±2.5°C. The above transient and periodical experiments showed that the present heat exchanger with PCM had useful characters of latent heat storage.

  16. Flooding characteristics of gas-liquid two-phase flow in a horizontal U bend pipe

    Energy Technology Data Exchange (ETDEWEB)

    Sakaguchi, T.; Hosokawa, S.; Fujii, Y. [Kobe Univ. (Japan)] [and others

    1995-09-01

    For next-generation nuclear reactors, hybrid safety systems which consist of active and passive safety systems have been planned. Steam generators with horizontal U bend pipelines will be used as one of the passive safety systems. It is required to clarify flow characteristics, especially the onset of flooding, in the horizontal U bend pipelines in order to examine their safety. Flooding in vertical pipes has been studied extensively. However, there is little study on flooding in the horizontal U bend pipelines. It is supposed that the onset of flooding in the horizontal U bend pipelines is different from that in vertical pipes. On the other hand, liquid is generated due to condensation of steam in pipes of the horizontal steam generators at the loss of coolant accident because the steam generators will be used as a condenser of a cooling system of steam from the reactor. It is necessary to simulate this situation by the supply of water at the middle of horizontal pipe. In the present paper, experiments were carried out using a horizontal U bend pipeline with a liquid supply section in the midway of pipeline. The onset of flooding in the horizontal U bend pipeline was measured. Effects of the length of horizontal pipe and the radius of U bend on the onset of flooding were discussed.

  17. Theoretical Study of Energy Characteristics of Artificial Receptor on Melamine in Pre-Polymerization Phase

    Directory of Open Access Journals (Sweden)

    K.M. Muzyka

    2015-03-01

    Full Text Available In terms of the thermodynamics of solutions (using the density functional theory (DFT method at RwB97XD/6-31G(d level of the theory the influence of the environment, as well as type of functional monomers and a ratio of "template molecule (melamine to monomer molecules" on the recognition properties of pre-polymerization complexes of "artificial receptor" against melamine has been explored. The geometries and energy characteristics of the "functional monomer-template" pre-polymerization complexes with the ratios 1:1, 2:1, 3:1 were obtained. There are acrylamido-2-methyl-1-propanesulfonic acid (AMPSA, ethylene glycol methacrylate phosphate, itaconic acid and acrylic acids were considered as functional monomers. It is shown that for all environments and there is a pattern, namely, the most energetically favorable monomer in the formation of pre-polymerization complexes with melamine is AMPSA. It is followed by itaconic and acrylic acid. In addition, the same sequence is stored at increase of the ratio between the molecules of monomers and melamine.

  18. Influence of spray characteristics on heat flux in dual phase spray impingement cooling of

    Directory of Open Access Journals (Sweden)

    Santosh Kumar Nayak

    2016-09-01

    Full Text Available The effects of variation of spray characteristics (mass flux, inlet pressure, flow rate, nozzle tip to target distance and plate thickness on heat flux were systematically investigated. The round spray released from a full cone internally mix atomizing nozzle was impinged with a wide range of air and water pressures on stationary hot steel surface of definite dimension. The effect of each parameter was examined while keeping others nearly fixed. Four different plate thicknesses i.e., 4 mm, 6 mm, 8 mm and 10 mm were tested and effect of plate thickness on heat transfer was determined. Surface heat flux at each experimental condition was computed from the transient temperature history measured by K-type thermocouples embedded at bottom surface of the plate. The mass impingement density was measured by the help of a simple mechanical patternator. The maximum surface heat flux of 4895.525 kW/m2 was achieved at an inlet water pressure of 4 bar, air pressure of 3 bar and nozzle height of 120 mm for an initial temperature of 850 °C of the 4 mm steel plate.

  19. Wave structure and flow amplitude-frequency characteristics in the turbine nozzle lattice in the presence of phase transition

    Science.gov (United States)

    Gribin, V. G.; Gavrilov, I. Yu.; Tishchenko, A. A.; Tishchenko, V. A.; Alekseev, R. A.

    2017-05-01

    This paper is devoted to the wave structure of a flow at its near- and supersonic velocities in a flat turbine cascade of profiles in the zone of phase transitions. The main task was investigation of the mechanics of interaction of the condensation jump with the adiabatic jumps of packing in a change of the initial condition of the flow. The obtained results are necessary for verification of the calculation models of the moisture-steam flow in the elements of lotic parts of the steam turbines. The experimental tests were made on a stand of the wet steam contour (WSC-2) in the Moscow Power Engineering Institute (MPEI, National Research University) at various initial states of steam in a wide range of Mach numbers. In the investigation of the wave structure, use was made of an instrument based on the Schlieren-method principle. The amplitude-frequency characteristics of the flow was found by measurement of static pressure pulsations by means of the piezo resistive sensors established on a bandage plate along the bevel cut of the cascade. It is shown that appearance of phase transitions in the bevel cut of the nozzle turbine cascade leads to a change in the wave structure of the flow. In case of condensation jump, the system of adiabatic jumps in the bevel cut of the cascade becomes nonstationary, and the amplitude-frequency characteristics of static pressure pulsations are restructured. In this, a change in the frequency pulsations of pressure and amplitude takes place. It is noted that, at near-sonic speeds of the flow and the state of saturation at the input, the low-frequency pulsations of static pressure appear that lead to periodic disappearance of the condensation jump and of the adiabatic jump. As a result, in this mode, the flow discharge variations take place.

  20. Determination of electrostatic force and its characteristics based on phase difference by amplitude modulation atomic force microscopy

    Science.gov (United States)

    Wang, Kesheng; Cheng, Jia; Yao, Shiji; Lu, Yijia; Ji, Linhong; Xu, Dengfeng

    2016-12-01

    Electrostatic force measurement at the micro/nano scale is of great significance in science and engineering. In this paper, a reasonable way of applying voltage is put forward by taking an electrostatic chuck in a real integrated circuit manufacturing process as a sample, applying voltage in the probe and the sample electrode, respectively, and comparing the measurement effect of the probe oscillation phase difference by amplitude modulation atomic force microscopy. Based on the phase difference obtained from the experiment, the quantitative dependence of the absolute magnitude of the electrostatic force on the tip-sample distance and applied voltage is established by means of theoretical analysis and numerical simulation. The results show that the varying characteristics of the electrostatic force with the distance and voltage at the micro/nano scale are similar to those at the macroscopic scale. Electrostatic force gradually decays with increasing distance. Electrostatic force is basically proportional to the square of applied voltage. Meanwhile, the applicable conditions of the above laws are discussed. In addition, a comparison of the results in this paper with the results of the energy dissipation method shows the two are consistent in general. The error decreases with increasing distance, and the effect of voltage on the error is small.

  1. Experimental investigation of thermal characteristics of lithium ion battery using phase change materials combined with metallic foams and fins

    Science.gov (United States)

    Deng, Y. C.; Zhang, H. Y.; Xia, X.

    2016-08-01

    Phase change materials are of great interest in energy storage and energy management applications due to their high latent heat and excellent cycling stability. In this paper, the thermal characteristics of phase change materials (PCM) for thermal management of cylindrical 18650 lithium-ion battery (LIB) were experimentally investigated. A commercial paraffin wax with a melting temperaturerange between 47 - 53.8oC was used in this study. A metal cylinder with a heater was used to emulate the heat generation from a battery, which was surrounded with the paraffin PCM and containted in a metal housing. The experiment was conducted in an environmental test chamber with controlled ambient temperatures and power inputs. Both the battery temperature and the housing wall temperature were measured during steady-state heating and cyclic heating conditions. Since PCM has low thermal conductivity, thermal enhancement techniques were investigated by adding metal foams (MFs) or combining metallic foam and fins into the PCM to enhance the thermal conductivity. The battery temperatures were measured for all the cases and the results were analyzed and discussed.

  2. Heat transfer characteristics of d-mannitol as a phase change material for a medium thermal energy system

    Science.gov (United States)

    Shibahara, Makoto; Liu, Qiusheng; Fukuda, Katsuya

    2016-09-01

    Melting process and heat transfer characteristics of d-mannitol were investigated experimentally and numerically to construct a fundamental database of the waste heat recovery systems for ships. d-Mannitol which has relatively high latent heat was selected in this study as a phase-change material for medium thermal energy storage. Experimental results indicate that the melting temperature and latent heat of d-mannitol were affected by the heating rate. The weight of d-mannitol did not decrease with the increase in temperature between 436 and 455 K. Moreover, numerical simulation was conducted using the commercial CFD code, ANSYS FLUENT. On the basis of the numerical simulation, melting process was affected by natural convection at the inner wall. As the heat flux of the cartridge heater input came from the inner wall, the liquid fraction increased from the inner wall to the outer wall through natural convection. The numerical result was compared with the experimental data. The temperature of the numerical simulation was approximately consistent with the experimental data. Moreover, the local heat transfer coefficients at the heater surface were calculated by the result of the numerical simulation. The heat transfer coefficients decreased during the phase change. It was considered that the heat transfer process changed from conductive heat transfer of solid state to natural convection heat transfer of liquid state as the liquid fraction increased with time.

  3. LPG gaseous phase electronic port injection on performance, emission and combustion characteristics of Lean Burn SI Engine

    Science.gov (United States)

    Bhasker J, Pradeep; E, Porpatham

    2016-08-01

    Gaseous fuels have always been established as an assuring way to lessen emissions in Spark Ignition engines. In particular, LPG resolved to be an affirmative fuel for SI engines because of their efficient combustion properties, lower emissions and higher knock resistance. This paper investigates performance, emission and combustion characteristics of a microcontroller based electronic LPG gaseous phase port injection system. Experiments were carried out in a single cylinder diesel engine altered to behave as SI engine with LPG as fuel at a compression ratio of 10.5:1. The engine was regulated at 1500 rpm at a throttle position of 20% at diverse equivalence ratios. The test results were compared with that of the carburetion system. The results showed that there was an increase in brake power output and brake thermal efficiency with LPG gas phase injection. There was an appreciable extension in the lean limit of operation and maximum brake power output under lean conditions. LPG injection technique significantly reduces hydrocarbon and carbon monoxide emissions. Also, it extremely enhances the rate of combustion and helps in extending the lean limit of LPG. There was a minimal increase of NOx emissions over the lean operating range due to higher temperature. On the whole it is concluded that port injection of LPG is best suitable in terms of performance and emission for LPG fuelled lean burn SI engine.

  4. Phase-field modeling of switchable diode-like current-voltage characteristics in ferroelectric BaTiO3

    Science.gov (United States)

    Cao, Y.; Shen, J.; Randall, C. A.; Chen, L. Q.

    2014-05-01

    A self-consistent model has been proposed to study the switchable current-voltage (I-V) characteristics in Cu/BaTiO3/Cu sandwiched structure combining the phase-field model of ferroelectric domains and diffusion equations for ionic/electronic transport. The electrochemical transport equations and Ginzburg-Landau equations are solved using the Chebyshev collocation algorithm. We considered a single parallel plate capacitor configuration which consists of a single layer BaTiO3 containing a single tetragonal domain orientated normal to the plate electrodes (Cu) and is subject to a sweep of ac bias from -1.0 to 1.0 V at 25 °C. Our simulation clearly shows rectifying I-V response with rectification ratios amount to 102. The diode characteristics are switchable with an even larger rectification ratio after the polarization direction is flipped. The effects of interfacial polarization charge, dopant concentration, and dielectric constant on current responses were investigated. The switchable I-V behavior is attributed to the polarization bound charges that modulate the bulk conduction.

  5. Effect of dietary antioxidant supplementation on reproductive characteristics of male broiler breeders during the post-peak production phase

    Directory of Open Access Journals (Sweden)

    Gustavo Eugênio Triques

    2016-09-01

    Full Text Available Because of their membrane constitution, sperm cells of male broiler breeders are prone to lipid peroxidation, which affects their fertilizing capacity. The aim of the present study was to evaluate the effects of antioxidant diet supplementation on the reproductive characteristics of 12 male broiler breeders (Cobb older than 50 weeks. The roosters were randomly distributed in a completely randomized experimental design with two treatments (treatment 1: commercial feed; treatment 2: commercial feed supplemented with canthaxanthin, lycopene, and vitamin C and 6 replicates. Semen samples were collected by abdominal massage, and then underwent evaluation of semen volume, sperm concentration, motility, vigor, and morphology. Morphometric analyses of testes, combs, and dewlaps were performed at 68 weeks. Testes samples were collected for morphometric analysis of seminiferous tubules and analysis of cellular proliferation in the germinal epithelium by using immunohistochemical staining with anti-proliferating cell nuclear antigen (anti-PCNA antibodies. Statistical data analysis was performed using the SAS software (SAS, 2002. No significant effects of antioxidant supplementation were observed on semen characteristics (p > 0.05. A significant positive effect of the antioxidant blend was observed on the percentage of normal sperm, dewlap weight and width, and testes weight and length (p < 0.05. PCNA-positive cell counts and morphometry of the seminiferous tubules were not affected by the treatment. Dietary antioxidant supplementation may represent a nutritional tool to increase fertility in male broiler breeder flocks during the post-peak production phase.

  6. Methods for testing Zernike phase plates and a report on silicon-based phase plates with reduced charging and improved ageing characteristics.

    Science.gov (United States)

    Marko, Michael; Meng, Xing; Hsieh, Chyongere; Roussie, James; Striemer, Christopher

    2013-11-01

    Imaging with Zernike phase plates is increasingly being used in cryo-TEM tomography and cryo-EM single-particle applications. However, rapid ageing of the phase plates, together with the cost and effort in producing them, present serious obstacles to widespread adoption. We are experimenting with phase plates based on silicon chips that have thin windows; such phase plates could be mass-produced and made available at moderate cost. The windows are coated with conductive layers to reduce charging, and this considerably extends the useful life of the phase plates compared to traditional pure-carbon phase plates. However, a compromise must be reached between robustness and transmission through the phase-plate film. Details are given on testing phase-plate performance by means of imaging an amorphous thin film and evaluating the power spectra of the images.

  7. Effects of Manganese Content on Solidification Structures, Thermal Properties, and Phase Transformation Characteristics in Fe-Mn-C Steels

    Science.gov (United States)

    Yang, Jian; Wang, Yu-Nan; Ruan, Xiao-Ming; Wang, Rui-Zhi; Zhu, Kai; Fan, Zheng-Jie; Wang, Ying-Chun; Li, Cheng-Bin; Jiang, Xiao-Fang

    2015-02-01

    The solidification structures and the thermal properties of Fe-Mn-C steel ingots containing different manganese contents have been investigated and the phase transformation characteristics have been revealed by Thermo-Calc to assist development of the continuous casting technology of Fe-Mn-C steels. The results show that the thermal conductivity of the 0Mn steel is higher than that of the 3Mn steel. The thermal conductivity of the 6Mn steel is the lowest in the three kinds of steels below 1023 K (750 °C) and the highest above 1173 K (900 °C). The 0Mn steel has the highest value of the proportion of equiaxed grain zone area in the three kinds of steels, whereas the 3Mn steel has the lowest value of it in the steels. Manganese has the effect of promoting the coarsening of grains. The microstructure is martensite and a little retained austenite (3.8 mass pct) in the 6Mn steel, whereas the microstructure is bainite in the 3Mn steel. The 0Mn steel is characterized by ferrite and pearlite. The mean thermal expansion coefficients of the steels are in the range from 1.0 × 10-5 to 1.6 × 10-5 K-1, and the determinations of mold tapers of the 6Mn and 3Mn steels can refer to low-carbon steel. Using RA steel is 873 K to 1073 K (600 °C to 800 °C), whereas those of the 3Mn steel and the 0Mn steel are 873 K to 1123 K (600 °C to 850 °C) and 873 K to 1173 K (600 °C to 900 °C), respectively. In the 6Mn and 3Mn steels, the deformation-induced ferrite (DIF) forms in sufficient quantities cause the recovery of the ductility at the low temperature end. However, since low strains are present when straightening, sufficient quantities of DIF cannot be formed. Thus, the ductility of the 6Mn and 3Mn steels cannot be improved during the continuous casting process. Manganese has the effect of enlarging the austenite phase region and reducing the δ-ferrite phase region and α-ferrite phase region.

  8. Adult HIV care resources, management practices and patient characteristics in the Phase 1 IeDEA Central Africa cohort

    Directory of Open Access Journals (Sweden)

    Jules Mushingantahe

    2012-11-01

    Full Text Available Introduction: Despite recent advances in the management of HIV infection and increased access to treatment, prevention, care and support, the HIV/AIDS epidemic continues to be a major global health problem, with sub-Saharan Africa suffering by far the greatest humanitarian, demographic and socio-economic burden of the epidemic. Information on HIV/AIDS clinical care and established cohorts’ characteristics in the Central Africa region are sparse. Methods: A survey of clinical care resources, management practices and patient characteristics was undertaken among 12 adult HIV care sites in four countries of the International Epidemiologic Databases to Evaluate AIDS Central Africa (IeDEA-CA Phase 1 regional network in October 2009. These facilities served predominantly urban populations and offered primary care in the Democratic Republic of Congo (DRC; six sites, secondary care in Rwanda (two sites and tertiary care in Cameroon (three sites and Burundi (one site. Results: Despite some variation in facility characteristics, sites reported high levels of monitoring resources, including electronic databases, as well as linkages to prevention of mother-to-child HIV transmission programs. At the time of the survey, there were 21,599 HIV-positive adults (median age=37 years enrolled in the clinical cohort. Though two-thirds were women, few adults (6.5% entered HIV care through prevention of mother-to-child transmission services, whereas 55% of the cohort entered care through voluntary counselling and testing. Two-thirds of patients at sites in Cameroon and DRC were in WHO Stage III and IV at baseline, whereas nearly all patients in the Rwanda facilities with clinical stage information available were in Stage I and II. WHO criteria were used for antiretroviral therapy initiation. The most common treatment regimen was stavudine/lamivudine/nevirapine (64%, followed by zidovudine/lamivudine/nevirapine (19%. Conclusions: Our findings demonstrate the

  9. Study on seafood volatile profile characteristics during storage and its potential use for freshness evaluation by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, Zhuomin; Li, Gongke; Luo, Lin; Chen, Guonan

    2010-02-05

    Seafood volatile profile characteristics at different storage phases are various and can be used for freshness evaluation during storage. It is imperative to obtain the full volatile information prior to the further study of seafood volatile profile characteristics during storage. Also, the efficient data-processing method is another important factor for the interpretation of seafood volatile profile characteristics during storage and related potential volatile markers. In this work, a new analytical strategy, including the efficient sampling technique, sensitive detection and suitable data-processing method, for seafood freshness evaluation was developed based on the volatile profile characteristics during storage. First, the study of volatiles of seafood samples including razor clam, redspot swimming crab and prawn at different storage phases were conducted by headspace solid phase microextraction (HSSPME) followed by gas chromatography-mass spectrometry (GC-MS) detection. Then, seafood volatile profile characteristics at different storage phases were statistically interpreted by a combination data-processing method including normalization, principle component analysis (PCA) and common model strategy. The different seafood volatile profile characteristics and potential volatile markers were attempted to be distilled. The results tentatively suggested that the different seafood volatile profile characteristics during storage could reflect the transitional changing seafood freshness and provide more precise warning information for seafood spoilage during storage than any single chemical markers. This work developed an analytical method for study of seafood volatile profile characteristics and tentatively proposed a new idea of using seafood volatile profile characteristics during storage for the freshness evaluation from the point of view of analytical chemistry.

  10. Nanoscale characteristics of triacylglycerol oils: phase separation and binding energies of two-component oils to crystalline nanoplatelets.

    Science.gov (United States)

    MacDougall, Colin J; Razul, M Shajahan; Papp-Szabo, Erzsebet; Peyronel, Fernanda; Hanna, Charles B; Marangoni, Alejandro G; Pink, David A

    2012-01-01

    Fats are elastoplastic materials with a defined yield stress and flow behavior and the plasticity of a fat is central to its functionality. This plasticity is given by a complex tribological interplay between a crystalline phase structured as crystalline nanoplatelets (CNPs) and nanoplatelet aggregates and the liquid oil phase. Oil can be trapped within microscopic pores within the fat crystal network by capillary action, but it is believed that a significant amount of oil can be trapped by adsorption onto crystalline surfaces. This, however, remains to be proven. Further, the structural basis for the solid-liquid interaction remains a mystery. In this work, we demonstrate that the triglyceride liquid structure plays a key role in oil binding and that this binding could potentially be modulated by judicious engineering of liquid triglyceride structure. The enhancement of oil binding is central to many current developments in this area since an improvement in the health characteristics of fat and fat-structured food products entails a reduction in the amount of crystalline triacylglycerols (TAGs) and a relative increase in the amount of liquid TAGs. Excessive amounts of unbound, free oil, will lead to losses in functionality of this important food component. Engineering fats for enhanced oil binding capacity is thus central to the design of more healthy food products. To begin to address this, we modelled the interaction of triacylglycerol oils, triolein (OOO), 1,2-olein elaidin (OOE) and 1,2-elaidin olein (EEO) with a model crystalline nanoplatelet composed of tristearin in an undefined polymorphic form. The surface of the CNP in contact with the oil was assumed to be planar. We considered pure OOO and mixtures of OOO + OOE and OOO + EEO with 80% OOO. The last two cases were taken as approximations to high oleic sunflower oil (HOSO). The intent was to investigate whether phase separation on a nanoscale took place. We defined an "oil binding capacity" parameter, B

  11. Characteristic Surface Oxide Film Cracking Behavior of a Fe-Ni-Cr Alloy under In-phase and Out-of-phase Thermo-mechanical Fatigue

    Institute of Scientific and Technical Information of China (English)

    HE Qingfu

    2008-01-01

    The surface oxide film cracking behavior of Fe-30Ni-20Cr alloy under in-phase and out-of-phase synchronizing thermal cycling with mechanical cycling was studied.Surface oxide film cracking along the grain boundary under in-phase overlapping was creep predominant fracture mechanisms.Strongly induced slip lines preceding were accompanied by the surface oxide film cracking under Out-of phase,and the shear cracking wa~ dominant mode.Negative mean stress could counteract a part of the tensile component of alternative stress,so as to delay the cracking process under in-phase,but positive mean stress overlapping the tensile alternative stress could accelerate the cycling cracking process under out-of-phase.

  12. The study on RBC characteristic in paroxysmal nocturnal hemoglobinuria (PNH) patients using common path interferometric quantitative phase microscopy

    Science.gov (United States)

    Park, Byung Jun; Won, Youngjae; Kim, Byungyeon; Lee, Seungrag

    2016-03-01

    We have studied the RBC membrane properties between a normal RBC and a RBC in Paroxysrnal nocturnal hemoglobinuria (PNH) patient using common path interferometric quantitative phase microscopy (CPIQPM). CPIQPM system has provided the subnanometer optical path length sensitivity on a millisecond. We have measured the dynamic thickness fluctuations of a normal RBC membrane and a RBC membrane in PNH patient over the whole cell surface with CPIQPM. PNH is a rare and serious disease of blood featured by destruction of red blood cells (RBCs). This destruction happens since RBCs show the defect of protein which protects RBCs from the immune system. We have applied CPIQPM to study the characteristic of RBC membrane in PNH patient. We have shown the morphological shape, volume, and projected surface for both different RBC types. The results have showed both RBCs had the similar shape with donut, but membrane fluctuations in PNH patient was shown to reveal the difference of temporal properties compared with a normal RBC. In order to demonstrate the practical tool of the CPIQPM technique, we have also obtained the time series thickness fluctuation outside a cell.

  13. Temperature Frequency Characteristics of Hexamethyldisiloxane (HMDSO Polymer Coated Rayleigh Surface Acoustic Wave (SAW Resonators for Gas-Phase Sensor Applications

    Directory of Open Access Journals (Sweden)

    Ekaterina I. Radeva

    2012-05-01

    Full Text Available Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and discusses temperature frequency characteristics (TFCs of solid hexamethyldisiloxane (HMDSO polymer coated sensor resonators using the Rayleigh surface acoustic wave (RSAW mode on ST-cut quartz. Using a RF-plasma polymerization process, RSAW sensor resonators optimized for maximum gas sensitivity have been coated with chemosensitive HMDSO films at 4 different thicknesses: 50, 100, 150 and 250 nm. Their TFCs have been measured over a (−100 to +110 °C temperature range and compared to the TFC of an uncoated device. An exponential 2,500 ppm downshift of the resonant frequency and a 40 K downshift of the sensor’s turn-over temperature (TOT are observed when the HMDSO thickness increases from 0 to 250 nm. A partial temperature compensation effect caused by the film is also observed. A third order polynomial fit provides excellent agreement with the experimental TFC curve. The frequency downshift due to mass loading by the film, the TOT and the temperature coefficients are unambiguously related to each other.

  14. An experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper presents an experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry (PDA). Blended fuels with DME mass fractions of 15%, 30% and pure diesel fuel were used to evaluate the effect of the DME concentration on the spray pattern, droplet size and velocity. The data for spray velocity vector and droplet size field were obtained. The experimental results reveal that the micro-explosive function exists in the jet of diesel-dimethyl ether (DME) blended fuels and the radial velocity of the blended fuels spray is larger than that of conventional diesel fuel spray near the nozzle exit. At the downstream part of the spray, the radial velocity and its attenuation rate of blended fuels are much more uniform and smaller than those of pure diesel spray. At the centerline of the spray, the attenuation rates of all spray axial velocities are similar. With the in- crease of DME concentration in the fuel, the spray angle and the exit velocity increase and the droplet size deceases.

  15. An experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin; HUANG Zhen; QIAO XinQi

    2009-01-01

    This paper presents an experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry (PDA). Blended fuels with DME mass fractions of 15%,30% and pure diesel fuel were used to evaluate the effect of the DME concentration on the spray pattern,droplet size and velocity. The data for spray velocity vector and droplet size field were obtained. The experimental results reveal that the micro-explosive function exists in the jet of diesel-dimethyl ether (DME) blended fuels and the radial velocity of the blended fuels spray is larger than that of conventional diesel fuel spray near the nozzle exit. At the downstream part of the spray, the radial velocity and its attenuation rate of blended fuels are much more uniform and smaller than those of pure diesel spray. At the centerline of the spray, the attenuation rates of all spray axial velocities are similar. With the increase of DME concentration in the fuel, the spray angle and the exit velocity increase and the droplet size deceases.

  16. Effect of supercritical water treatment on porous structure, liquid-phase adsorption and regeneration characteristics of activated anthracite

    Energy Technology Data Exchange (ETDEWEB)

    Tanthapanichakoon, W.; Sittipraneed, S.; Japthong, P.; Charinpanitkul, T.; Boon-Amnuayvitaya, V.; Nakagawa, K.; Tamon, H. [National Nanotechnological Centre, Pathumthani (Thailand)

    2006-06-15

    Microporous activated anthracite was produced from waste anthracite powders by the conventional steam activation. The activated anthracite was also treated by supercritical water reaction (SWR) by using distilled water and hydrogen peroxide solution as a liquid medium for SWR treatment. It was found that SWR treatment can improve the mesoporosity of the activated anthracite though the micropore volume was reduced by the treatment. In liquid-phase adsorption and supercritical water regeneration studies, phenol and organic dye RED 31 were selected as the representative adsorbates. The adsorption and regeneration characteristics of activated anthracite were compared with those of a commercial activated carbon. The results indicate that the activated anthracite prepared showed comparable phenol adsorption capacity but significantly lower dye adsorption capacity than the commercial one. However, supercritical water regeneration efficiency was remarkably high. The first/second regeneration efficiencies of commercial activated carbon and activated anthracite exhausted with phenol were 55/55 and 65/65%, respectively, and in the case of RED 31, 78/79 and 338/317%, respectively, with losses of activated carbon less than 4% per regeneration. Because of little loss of activated carbon during successive regenerations, this SWR regeneration method was suitable for regenerating spent activated carbon or anthracite.

  17. Pressure drop and heat transfer characteristics for single-phase developing flow of water in rectangular microchannels

    Science.gov (United States)

    Mirmanto; Kenning, D. B. R.; Lewis, J. S.; Karayiannis, T. G.

    2012-11-01

    Experiments were conducted to investigate the pressure drop and heat transfer characteristics of single-phase flow of de-ionized water in single copper microchannels of hydraulic diameters 0.438 mm, 0.561 mm and 0.635 mm. The channel length was 62 mm. The experimental conditions covered a range of mass flux from 500 to 5000 kg/m2 s in the laminar, transitional and low Reynolds number turbulent regimes. Pressure drop was measured for adiabatic flows with fluid inlet temperatures of 30°C, 60°C and 90°C. In the heat transfer tests, the heat flux ranged from 256 kW/m2 to 519 kW/m2. Friction factors and Nusselt numbers determined from the measurements were higher than for fully-developed conditions, but in reasonable agreement with predictions made using published solutions for hydrodynamically and thermally developing flow. When entrance effects, experimental uncertainties, heat losses, inlet and exit losses, thermal boundary conditions and departure from laminar flow were considered, the results indicate that equations developed for flow and heat transfer in conventional size channels are applicable for water flows in microchannels of these sizes.

  18. Phase relationships in 500℃ isothermal section of Ho-Ni-Ti 牋爐ernary system and the fundamental characteristics of the related compounds

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By means of X-ray powder diffraction (powder XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and X-ray electron dispersed spectrum microanalysis (EDS), the isothermal section at 500℃ in Ho-Ni-Ti ternary system is determined. Intermetallic phases in this section and the relationships among them are studied. In addition, the characteristics of some of these compounds are analyzed. This section consists of 13 singlephase regions, 23 two-phase regions and 11 three-phase regions. The existence of 10 binary compounds is confirmed.No ternary. compound is found.

  19. Study on the Characteristics of SiO2 Distribution and Silicate Phases in MgO—ZrO2 Composites

    Institute of Scientific and Technical Information of China (English)

    ZHUBoquan; GANFeifang; 等

    2000-01-01

    This work studied the characteristics of SiO2 distribution and structure of silicate phases in MgO-ZrO2 composites synthesizedby raw materials of light fired magnesite nd zircon,The results indicate that 30 wt%-40wt% SiO2 content in the system is existed in the form of crystalline of forsterite (M2S),the remaindering of SiO content (60wt%0-70wt%) is existed in the glass phase,The chemical composition of glass phase is well agreed with the chemical composition of monticellite(CMS).

  20. Study on each phase characteristics of the whole coal life cycle and their ecological risk assessment-a case of coal in China.

    Science.gov (United States)

    Dai, Wenting; Dong, Jihong; Yan, Wanglin; Xu, Jiren

    2017-01-01

    The paper divided the whole coal life cycle, explained each phase characteristics, and took coal mine in China as a study case to assess the ecological risk in coal utilization phase. The main conclusions are as follows: (1) the whole coal life cycle is divided into coal mining, processing, transportation, utilization, and waste disposal. (2) The key points of production organization and characteristics in the five phases have great differences. The coal mining phase is characterized by the damage of the key ecological factors (water, soil, atmosphere, vegetation, etc.) damaged while the coal processing phase by discharging waste. The characteristics in coal transportation phase mainly performance as escaping and migration of atmospheric pollutants. In coal utilization phase, the main characteristics are aggravation of greenhouse effect. The main characteristics of waste disposal phase are accumulation of negative ecological effects on the land. (3) The ecological risk of soil heavy metals is serious in coal utilization phase. The potential ecological hazard coefficients of Pb and As in coal, residue and ash are all lower than 40, presenting low environmental impact on soil; the potential ecological risk coefficients of Cd are higher than 60, nearly half of their potential ecological risk coefficients are higher than 160, which presents high environmental pollution impact on soil; Hg's potential ecological risk coefficients are higher than 320, presenting the highest environmental pollution impact on soil; the comprehensive pollution indexes in coal, residue, and ash are relatively high, which means the pollution hazard potential to soil environment is high. (4) The ecological risk of the atmospheric solid suspended matter is relatively strong in coal utilization phase. The ecological risk of Cd and As in primary flue gas is both lower than net flue gas. The geoaccumulation indexes of Cd and Hg in primary flue gas and net flue gas are both higher than 5, presenting

  1. Comparison of the quench and fault current limiting characteristics of the flux-coupling type SFCL with single and three-phase transformer

    Science.gov (United States)

    Jung, Byung Ik; Cho, Yong Sun; Park, Hyoung Min; Chung, Dong Chul; Choi, Hyo Sang

    2013-01-01

    The South Korean power grid has a network structure for the flexible operation of the system. The continuously increasing power demand necessitated the increase of power facilities, which decreased the impedance in the power system. As a result, the size of the fault current in the event of a system fault increased. As this increased fault current size is threatening the breaking capacity of the circuit breaker, the main protective device, a solution to this problem is needed. The superconducting fault current limiter (SFCL) has been designed to address this problem. SFCL supports the stable operation of the circuit breaker through its excellent fault-current-limiting operation [1-5]. In this paper, the quench and fault current limiting characteristics of the flux-coupling-type SFCL with one three-phase transformer were compared with those of the same SFCL type but with three single-phase transformers. In the case of the three-phase transformers, both the superconducting elements of the fault and sound phases were quenched, whereas in the case of the single-phase transformer, only that of the fault phase was quenched. For the fault current limiting rate, both cases showed similar rates for the single line-to-ground fault, but for the three-wire earth fault, the fault current limiting rate of the single-phase transformer was over 90% whereas that of the three-phase transformer was about 60%. It appears that when the three-phase transformer was used, the limiting rate decreased because the fluxes by the fault current of each phase were linked in one core. When the power loads of the superconducting elements were compared by fault type, the initial (half-cycle) load was great when the single-phase transformer was applied, whereas for the three-phase transformer, its power load was slightly lower at the initial stage but became greater after the half fault cycle.

  2. Friction and wear characteristics of Al-Cu/C composites synthesized using partial liquid phase casting process

    Energy Technology Data Exchange (ETDEWEB)

    Ng, W.B.; Gupta, M.; Lim, S.C. [Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore (Singapore)

    1997-10-01

    During the sliding of aluminium alloys dispersed with graphite particulates, a layer of graphite is usually present at the sliding interface. This tribo-layer significantly reduces the amount of direct metal-to-metal contact, giving rise to low friction and a low rate of wear, making these composites useful candidate materials for anti-friction applications. Such self-lubricating composites are commonly fabricated via the squeeze casting, slurry casting or powder metallurgy route. These processes are expensive while the less-expensive conventional casting route is limited by the agglomeration of graphite particles in the composites, giving rise to poor mechanical properties. In this work, graphite particulate-reinforced Al-4.5 wt.% Cu composites with two effective graphite contents (Al-4.5 Cu/4.2 wt.% C and Al-4.5 Cu/6.8 wt.% C) were synthesized through an innovative partial liquid phase casting (rheocasting) technique, which is a modification of the conventional casting process. Unlubricated (without the use of conventional liquid lubrication) friction and wear performance of these composites as well as the un-reinforced aluminium alloy was determined using a pin-on-disk tester. The results revealed that the graphite-reinforced composites have a higher wear rate than the un-reinforced matrix alloy while their frictional characteristics are very similar within the range of testing conditions. Combining these with the information gathered from worn-surface examinations and wear-debris analysis, it is suggested that there exists a certain threshold for the amount and size of graphite particulates in these composites to enable them to have improved tribological properties. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

  3. Characteristics of adverse drug reactions in a vemurafenib early post-marketing phase vigilance study in Japan.

    Science.gov (United States)

    Uhara, H; Kiyohara, Y; Tsuda, A; Takata, M; Yamazaki, N

    2017-07-03

    Post-approval research or monitoring is important to determine real-world safety of new products; however, evidence is scant for vemurafenib in Japanese patients. In Japan, a unique system is officially obligated to investigate post-approval safety. Here we report the first adverse drug reaction (ADR) data from vemurafenib-treated Japanese patients with metastatic melanoma. Data were collected in an early post-marketing phase vigilance (EPPV) study. ADRs were events for which a causal relationship with vemurafenib could not be ruled out or was unknown. ADR data were collected for patients treated with vemurafenib (960 mg bid) between 26 February and 25 August 2015. Among 95 patients, 46 patients had 118 ADRs (24 serious ADRs in 13 patients). The most common serious ADRs were hypersensitivity (n = 1; 3 events), arthralgia (n = 2; 2 events), pyrexia (n = 2; 2 events) and drug eruption (n = 2; 2 events). Seven patients had serious skin disorders or hypersensitivity, six of whom had prior anti-programmed cell death-1 (PD-1) antibodies 5-35 days before starting vemurafenib. ADR reports of serious skin disorders appeared to be collected more rapidly than previously reported. Cutaneous squamous cell carcinoma developed in only one patient. EPPV in Japanese vemurafenib-treated patients identified no new safety signals. The most serious skin and hypersensitivity ADRs occurred in patients with prior anti-PD-1 exposure. Cutaneous squamous cell carcinoma appeared to be rare in Japanese patients. Further research is needed to clarify whether prior treatment with anti-PD-1 agents or racial differences affect the characteristic profile of cutaneous ADRs in Japanese patients.

  4. Analysis of torque-current characteristic of brushless DC motor driven by three-phase H-bridge

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Presents the simulation and analysis of the steady state characteristic of a brushless DC motor studies the torque-current characteristic of the motor as well and discusses the design of a current-measure circuit for torque controlling.

  5. Flow regime, void fraction and interfacial area transport and characteristics of co-current downward two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Lokanathan, Manojkumar [School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907-2088 (United States); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States)

    2016-10-15

    Highlights: • Downward flow regime maps and models were studied for 25.4 to 101.6 mm pipe diameters. • Effect of flow inlet on flow transition, void & interfacial area profile were studied. • Bubble void profiles were associated with the interfacial forces for downward flow. • Flow regime pressure drop and interfacial friction factor were studied. • The most applicable and accurate downward drift-flux correlation was determined. - Abstract: Downward two-phase flow is observed in light water reactor accident scenarios such as loss of coolant accident (LOCA) and loss of heat sink accident (LOHS) due to loss of feed water or a secondary pipe break. Hence, a comprehensive literature review has been performed for the co-current downward two-phase flow with information on the flow regime transitions and flow characteristics for each regime in the downward flow. The review compares the experimental data of the flow regime map and the current available transition models. Objectivity of the data varies on the method utilized as a certain degree of subjectivity is still present in the most objective method. Nevertheless, experimental data through subjective methods such as direct visualization or analysis of a wire mesh sensor (WMS) data were still studied in this review. Despite the wide range of flow regime data for numerous pipe sizes, a consensus was not reached for the effect of pipe sizes on flow regime transition. However, it is known that a larger pipe results in greater degree of coalescence at lower gas flow rates (Hibiki et al., 2004). The introduction of a flow straightener at the inlet led to less coring and fluid rotation and inevitably, reduced bubble coalescence. This also resulted in the disappearance of the kinematic shock wave phenomenon, contrary to an inlet without a flow straightener. The effect of flow inlet, flow location, pipe diameter and bubble interfacial forces on the radial distribution as well as bubble coalescence and breakup rate

  6. Determination of torque speed current characteristics of a brushless DC motor by utilizing back-EMF of non-energized phase

    Science.gov (United States)

    Jang, G. H.; Yeom, J. H.; Kim, M. G.

    2007-03-01

    This paper presents a method to determine the torque constant and the torque-speed-current characteristics of a brushless DC (BLDC) motor by utilizing back-EMF variation of nonenergized phase. It also develops a BLDC motor controller with a digital signal processor (DSP) to monitor its current, voltage and speed in real time. Torque-speed-current characteristics of a BLDC motor are determined by using the proposed method and the developed controller. They are compared with the torque-speed-current characteristics measured by dynamometer experimentally. This research shows that the proposed method is an effective method to determine the torque constant and the torque-speed-current characteristics of the BLDC motor without using dynamometer.

  7. Determination of torque-speed-current characteristics of a brushless DC motor by utilizing back-EMF of non-energized phase

    Energy Technology Data Exchange (ETDEWEB)

    Jang, G.H. [Department of Mechanical Engineering, Hanyang University, 17 Haengdangdong, Seongdonggu, Seoul 133-791 (Korea, Republic of)]. E-mail: ghjang@hanyang.ac.kr; Yeom, J.H. [Department of Mechanical Engineering, Hanyang University, 17 Haengdangdong, Seongdonggu, Seoul 133-791 (Korea, Republic of); Kim, M.G. [Department of Mechanical Engineering, Hanyang University, 17 Haengdangdong, Seongdonggu, Seoul 133-791 (Korea, Republic of)

    2007-03-15

    This paper presents a method to determine the torque constant and the torque-speed-current characteristics of a brushless DC (BLDC) motor by utilizing back-EMF variation of nonenergized phase. It also develops a BLDC motor controller with a digital signal processor (DSP) to monitor its current, voltage and speed in real time. Torque-speed-current characteristics of a BLDC motor are determined by using the proposed method and the developed controller. They are compared with the torque-speed-current characteristics measured by dynamometer experimentally. This research shows that the proposed method is an effective method to determine the torque constant and the torque-speed-current characteristics of the BLDC motor without using dynamometer.

  8. Effect of dietary energy levels and phase feeding by protein levels on growth performance, blood profiles and carcass characteristics in growing-finishing pigs.

    Science.gov (United States)

    Hong, J S; Lee, G I; Jin, X H; Kim, Y Y

    2016-01-01

    Providing of insufficient nutrients limits the potential growth of pig, while feeding of excessive nutrients increases the economic loss and causes environment pollution. For these reasons, phase feeding had been introduced in swine farm for improving animal production. This experiment was conducted to evaluate the effects of dietary energy levels and phase feeding by protein levels on growth performance, blood profiles and carcass characteristics in growing-finishing pigs. A total of 128 growing pigs ([Yorkshire × Landrace] × Duroc), averaging 26.62 ± 3.07 kg body weight, were assigned in a 2 × 4 factorial arrangement with 4 pigs per pen. The first factor was two dietary energy level (3,265 kcal of ME/kg or 3,365 kcal of ME/kg), and the second factor was four different levels of dietary protein by phase feeding (1growing(G)-2finishing(F) phases, 2G-2F phases, 2G-3F phases and 2G-3F phases with low CP requirement). In feeding trial, there was no significant difference in growth performance. The BUN concentration was decreased as dietary protein level decreased in 6 week and blood creatinine was increased in 13 week when pigs were fed diets with different dietary energy level. The digestibility of crude fat was improved as dietary energy levels increased and excretion of urinary nitrogen was reduced when low protein diet was provided. Chemical compositions of longissimus muscle were not affected by dietary treatments. In backfat thickness (P2) at 13 week, pigs fed high energy diet had thicker backfat thickness (P = 0.06) and pigs fed low protein diet showed the trend of backfat thinness reduction (P = 0.09). In addition, water holding capacity was decreased (P = 0.01) and cooking loss was increased (P = 0.07) as dietary protein level reduced. When pigs were fed high energy diet with low subdivision of phase feeding, days to 120 kg market weight was reached earlier compared to other treatments. Feeding the low energy diet

  9. Chemical and morphological characteristics of solid metal-bearing phases deposited in snow and stream sediment as indicators of their origin.

    Science.gov (United States)

    Miler, Miloš; Gosar, Mateja

    2015-02-01

    Detailed scanning electron microscopy/energy dispersive spectroscopy of metal-bearing particles in snow deposits and stream sediment from a steelworks area was performed. Identified metal-bearing phases were apportioned according to their chemical and morphological characteristics to anthropogenic phases and secondary weathering products. Anthropogenic metal-bearing phases are the most abundant in both media and are represented by various irregular ferrous oxides, ferrous alloys, spherical ferrous oxides, and ferrous silicates with variable contents of Cr, Mn, Ni, V, W, and Mo. Secondary weathering products are Al silicates, Fe oxy-hydroxides, and Fe oxy-hydroxy sulfates with minor contents of transition metals, resulting from weathering of anthropogenic phases and Pb-Zn ore minerals from a closed Pb-Zn mine located upstream from the study area. Comparison of anthropogenic metal-bearing phases in both media showed agreement in their compositions and morphologies and indicated their sources are high-temperature processes in steel production. It also showed that spherical metal-bearing phases were transported by the same transport medium, which is the atmosphere, while other phases were transported into stream sediment mostly by other pathways, such as precipitation runoff over contaminated surfaces.

  10. Effects of phase-feeding dietary phosphorus on survival, growth, and processing characteristics of rainbow trout Oncorhynchus mykiss

    Science.gov (United States)

    Lellis, W.A.; Barrows, F.T.; Hardy, R.W.

    2004-01-01

    A factorial experiment involving eight diets and three feeding periods was conducted to determine the minimal level of dietary phosphorus required to maintain survival, growth, and processing characteristics of post-juvenile rainbow trout. Trout were reared to an average size of 200, 300, or 400 g using a commercial feed (1.20% P), then allotted by triplicate groups of nine fish to one of seven experimental diets containing logarithmic increments of dietary phosphorus (0.15%%, 0.21%, 0.30%, 0.42%, 0.60%, 0.85%, and 1.20% P) or a commercial trout feed (1.20% P). At an average weight of 550 g, fish were transported to a commercial processing plant, mechanically filleted, and evaluated for quality. Fish survival and weight gain increased quadratically with increased dietary phosphorus for fish started on treatment at 200 and 300 g, but were similar among all fish started at 400 g. Phosphorus retention decreased with increasing dietary phosphorus level, from approximately 88% in groups fed diets containing 0.21% phosphorus to between 23% and 32% in groups fed diets containing 0.85% phosphorus. Calculated phosphorus losses increased as dietary phosphorus levels increased, from a low of approximately 0.4 g phosphorus kg-1 fish weight gain to between 9.5 and 13 g phosphorus kg-1 fish weight gain at the highest dietary phosphorus level. Dietary phosphorus did not affect carcass moisture, protein, lipid, or ash, but carcass phosphorus increased with increased dietary phosphorus among fish started on treatment at 200 and 300 g. There were no differences among any treatment group in carcass dressing or finishing percentage, or visual or textural appeal. The results indicate that available phosphorus levels can be reduced in rainbow trout diets to 0.60% at 200 g, to 0.30% at 300 g, or to 0.15% at 400 g live weight without loss in production or product quality in fish harvested at 550 g. Using these phase-feeding strategies would reduce the amount of phosphorus fed to the fish

  11. Reversed-phase high performance liquid chromatography (RP-HPLC) characteristics of some 9,10-anthraquinone derivatives using binary acetonitrile-water mixtures as mobile phase.

    Science.gov (United States)

    Hemmateenejad, B; Shamsipur, M; Safavi, A; Sharghi, H; Amiri, A A

    2008-10-19

    The retention behavior of 28 synthesized 9,10-anthraquinone derivatives in a reversed-phase (RP) high performance liquid chromatography (HPLC) system has been studied on a C18-RP column using acetonitrile-water mixtures as mobile phase. The influences of the composition of mobile phase and the solute structure on the retention times of 9,10-anthraquinone derivatives were investigated by linear solvation free energy relationship (LSFER) and quantitative structure-retention relationship (QSRR) analyses. Among different solvatochromic parameters of solvent systems, their polarity/polarizability parameter (pi*) was identified as the controlling factor affecting retention behavior of these compounds. A four-parametric QSRR model was obtained between solute structures and retention indices. Finally, a unified model containing both the molecular structure parameters and mobile phase properties was developed to describe the chromatographic behavior of the systems studied. The resulted QSRR models could explain and predict higher than 90% of variances in the retention indices. Among the solvent properties, polarity/polarizability parameter (pi*), and among the solute properties, HATS5v (leverage-weighted autocorrelation of lag 5/weighted by atomic van der Waals volumes, GETAWAY descriptors), Mor14p (3D-MoRSE-signal 14/weighted by atomic polarizabilities, 3D-MoRSE descriptors), GATS5p (Geary autocorrelation-lag 5/weighted by atomic polarizabilities, 2D autocorrelations) and R6u+(R maximal autocorrelation of lag 6/unweighted, GETAWAY descriptors) were identified as controlling factors in the RP-HPLC behavior of 9,10-anthraquinone derivatives in actonitrile-water binary solvents.

  12. Contrast enhancement characteristics of hepatocellular carcinoma according to the tumor size on two-phase scan with spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jee Eun; Yang, Dai Mo; Yoon, Myung Hwan; Chun, Seok; Kim, Hyung Sik; Chung, Hyo Seon; Lee, Young Seok [Chungang Gil Hospital, Incheon (Korea, Republic of)

    1996-01-01

    To determine the enhancing patterns of hepatocellular carcinoma(HCC) and the difference of enhancing patterns according to the tumor size, using spiral CT. We reviewed 213 lesions in 76 patients who had been clinically or histopathologically diagnosed as HCC sufferer. The tumors were divided into three groups, according to size(<3 cm, 3-5 cm and >5 cm). The enhancing patterns of tumor and capsule in the early and delayed phase were analysed. The enhancing patterns of the tumor were divided into five types(high, peripheral high, mixed, iso and low attenuation) in the early phase and four types(contral high, mixed, iso, and low attenuation) in the delayed phase. The enhancing patterns of the capsule were divided into three types such as iso, low and high attenuation. High attenuating lesions in the early phase were as follows; below 3 cm, 72%:3-5 cm, 60%:above 5 cm, 49%. Mixed attenuating lesions in the early phase were as follows;below 3 cm, 1%;3-5 cm, 22%;above 5 cm, 36%. Thus, most Hx were high attenuation type in the early phase, but as the tumor became larger, less high attenuation and more mixed attenuation was demonstrated(p<0.01). There was no difference of enhancing patterns according to the tumor size in peripheral high, iso and low-attenuating lesions. In the delayed phase most of the hepatomas appeared as totally hypodense lesions. For capsules, the results were as follows; below 3 cm, 20%:3-5 cm, 58%: above 5 cm, 73%. As the tumors became larger, more capsules were demonstrated(p<0.01). The capsules were visualized as iso or low attenuating rum in the early phase and high attenuating rim in the delayed phase. To determine the enhancing patterns of HCC using spiral CT is considered to be helpful in the diagnosis of HCC.

  13. Predicting the influence of compressibility and thermal and flow distribution asymmetry on the frequency-response characteristics of multitube two-phase condensing flow systems

    Energy Technology Data Exchange (ETDEWEB)

    Kobus, C.J.; Wedekind, G.L.; Bhatt, B.L.

    2000-02-01

    An equivalent single-tube model concept was extended to predict the frequency-response characteristics of multitube two-phase condensing flow systems, complete with the ability to predict the influence of compressibility and thermal and flow distribution asymmetry. The predictive capability of the equivalent single-tube model was verified experimentally with extensive data that encompassed a three-order-of-magnitude range of frequencies, and a wide range of operating parameters.

  14. Estimating multi-phase pore-scale characteristics from X-ray tomographic data using cluster analysis-based segmentation

    DEFF Research Database (Denmark)

    Wildenschild, D.; Culligan, K.A.; Christensen, Britt Stenhøj Baun

    2006-01-01

    of individual pores and interfaces. However, separation of the various phases (fluids and solids) in the grey-scale tomographic images has posed a major problem to quantitative analysis of the data. We present an image processing technique that facilitates identification and separation of the various phases...... characterization. The results clearly illustrate the advantage of using X-ray tomography together with cluster analysis-based image processing techniques. We were able to obtain detailed information on pore scale distribution of air and water phases, as well as quantitative measures of air bubble size and air......Recent advances in experimental techniques have made it possible to characterize and distinguish such micro-scale entities as fluid phase ditributions and pore geometry in porous media. In particular, non-destructive synchrotron based X-ray computed microtomography allows 3D resolution...

  15. Effect of Mechanical Stress on Magnetic States and Hysteresis Characteristics of a Two-Phase Nanoparticles System

    Directory of Open Access Journals (Sweden)

    Leonid Lazarevich Afremov

    2013-01-01

    Full Text Available In terms of the two-phase nanoparticles model, the effect of mechanical stress on the magnetic state of both uniaxial and multiaxial heterophase magnetic is investigated. The spectrum of critical fields of reversal of phases' magnetic moments was calculated and phase diagrams were drawn to assess the effect of mechanical stress on the degree of metastability of two-phase nanoparticles' magnetic states. By the example of epitaxial cobalt-coated -Fe2O3 particles, a theoretical analysis of the effect of uniaxial mechanical stress on the magnetization of a system of noninteracting heterophase nanoparticles is investigated. It was shown that tension reduced and compression increased coercive force , while the residual saturation magnetization was not changed under the influence of mechanical stress.

  16. Distribution of Polycyclic Aromatic Hydrocarbons between the Particulate and the Gas Phase of Mainstream Cigarette Smoke in Relation to Cigarette Technological Characteristics

    Directory of Open Access Journals (Sweden)

    Kalaitzoglou M

    2014-12-01

    Full Text Available Particulate- and gas-phase polycyclic aromatic hydrocarbons (PAHs were determined in the mainstream smoke (MSS of 59 manufactured cigarette brands (commercially available brands of unknown tobacco and blend type with variable ‘tar’ yields and physical/technological characteristics. Depending on the existence/absence of filter, the ‘tar’ yield indicated on the packet, and the cigarette length and diameter, the examined cigarette brands were classified into 15 groups: non filter (NF, high (H, medium (M, light (L, super light (SL, ultra light (UL, one-tar yields (O, 100 mm long cigarettes (H-100, L-100, SL-100, UL-100, O-100, and slim cigarettes (SL-SLIM, UL-SLIM, O-SLIM. Cigarettes were smoked in a reference smoking machine equipped with glass fibre filters for collection of PAHs bound to total particulate matter (TPM, and polyurethane foam plugs (PUF for collection of gas-phase PAHs. The relationships of gas- and particulate-phase concentrations of PAHs (ng/cig with the contents of typical MSS components, such as TPM, ‘tar’, nicotine and carbon monoxide were investigated. In addition, the phase partitioning of PAHs in MSS was evaluated in relation to the technological characteristics of cigarettes.

  17. Seasonal and diurnal characteristics of water soluble inorganic compounds in the gas and aerosol phase in the Zurich area

    Directory of Open Access Journals (Sweden)

    R. Fisseha

    2006-01-01

    Full Text Available Gas and aerosol samples were taken using a wet effluent diffusion denuder/aerosol collector (WEDD/AC coupled to ion chromatography (IC in the city of Zurich, Switzerland from August to September 2002 and in March 2003. Major water soluble inorganic ions; nitrate, sulfate, and nitrite were analyzed online with a time resolution of two hours for the gas and aerosol phase. The fraction of water soluble inorganic anions in PM10 varied from 15% in August to about 38% in March. Seasonal and diurnal variations of nitrate in the gas and aerosol phase were observed with more than 50% of the total nitrate in the gas phase during August and more than 80% of nitrate in the aerosol phase during March exceeding the concentration of sulfate by a factor of 2. Aerosol sulfate, on the other hand, did not show significant variability with season. However, in the gas phase, the SO2 concentration was 6.5 times higher in winter than in summer. Nitrous acid (HONO also showed a diurnal variation in both the gas and aerosol phase with the lowest concentration (0.2–0.6 µg/m3 in the afternoon. The primary pollutants, NO, CO and SO2 mixing ratios were often at their highest between 04:00–10:00 local time due to the build up of fresh vehicle emission under a nocturnal inversion.

  18. Formation and characteristics of aqueous two-phase systems formed by a cationic surfactant and a series of ionic liquids.

    Science.gov (United States)

    Wei, Xi-Lian; Wang, Xiu-Hong; Ping, A-Li; Du, Pan-Pan; Sun, De-Zhi; Zhang, Qing-Fu; Liu, Jie

    2013-11-15

    Aqueous two-phase systems (ATPS) were obtained in the aqueous mixtures of a cationic surfactant and a series of ionic liquids (ILs). The effects of IL structure, temperature and additives on the phase separation were systematically investigated. The microstructures of some ATPS were observed by freeze-fracture replication technique. Lyotropic liquid crystal was found in the bottom phase besides micelles under different conditions. Remarkably, both IL structure and additives profoundly affected the formation and properties of the ATPSs. The phase separation can be attributed to the existence of different aggregates and the cation-π interactions of the cationic surfactant with the ILs, which has a significant role in the formation of ATPS. The extraction capacity of the studied ATPS was also evaluated through their application in the extraction of two biosubstances. The results indicate that the ILs with BF4(-) as anion show much better extraction efficiencies than the corresponding ILs with Br(-) as anion do under the same conditions. l-Tryptophan was mainly distributed into the NPTAB-rich phase, while methylene blue and capsochrome were mainly in the IL-rich phase.

  19. Influence of growing phase feed efficiency classification on finishing phase growth performance and carcass characteristics of beef steers fed different diet types.

    Science.gov (United States)

    Russell, J R; Lundy, E L; Minton, N O; Sexten, W J; Kerley, M S; Hansen, S L

    2016-07-01

    A 5-yr study was conducted using 985 crossbred steers (464 kg [SD 32]) fed in 6 separate, replicated groups to determine the influence of growing phase (GP) feed efficiency (FE) classification and diet type on finishing phase (FP) FE of steers. During the GP at the University of Missouri, steers were fed either a whole shell corn-based diet (G-Corn; 528 steers) or a roughage-based diet (G-Rough; 457 steers) using GrowSafe feed bunks to measure DMI for 69 to 89 d. At the end of the GP, steers were ranked by residual feed intake (RFI) within diet, shipped to Iowa State University, and blocked into FP pens (5 to 6 steers/pen) by GP diet and RFI rank (upper, middle, or lower one-third). Steers were transitioned to either FP cracked corn- or byproduct-based diets and fed until 1.27 cm backfat was reached. After completion of the sixth group, average GP G:F within GP diet was calculated for each FP pen (168 total pens) using GP initial BW as a covariate (G-Corn: 0.207 [SD 0.038]; G-Rough: 0.185 [SD 0.036]). Pens were classified as highly feed efficient (HFE; >0.5 SD from the G:F mean; 58 pens), mid feed efficient (MFE; ±0.5 SD from the G:F mean; 60 pens), or lowly feed efficient (LFE; MFE and LFE and greater ( = 0.02) for MFE versus LFE. Growing phase diet × FE classification effects were detected ( ≤ 0.01) for FP final BW (FBW), ADG, and DMI. Among G-Rough steers, HFE and MFE had greater ( ≤ 0.04) FBW and ADG than LFE, but among G-Corn steers, LFE had heavier ( = 0.03) FBW than HFE whereas ADG was unaffected ( ≥ 0.2) by FE classification. Dry matter intake was unaffected ( ≥ 0.3) by FE classification among G-Rough steers, but among G-Corn steers, LFE had greater ( ≤ 0.003) DMI than MFE and HFE. Overall, differences in FP G:F between FE classifications were driven by different factors depending on diet; ADG differed among roughage-grown steers and DMI differed among corn-grown steers. Ultimately, steers classified as HFE during the GP still had superior FE

  20. Insights into solid phase characteristics and release of heavy metals and arsenic from industrial sludge via combined chemical, mineralogical, and microanalysis.

    Science.gov (United States)

    Dung, Tran Thi Thu; Golreihan, Asefeh; Vassilieva, Elvira; Phung, Nguyen Ky; Cappuyns, Valérie; Swennen, Rudy

    2015-02-01

    This study investigates the solid phase characteristics and release of heavy metals (i.e., Cd, Co, Cu, Cr, Mo, Ni, Pb, and Zn) and arsenic (As) from sludge samples derived from industrial wastewater treatment plants. The emphasis is determining the influence of acidification on element mobilization based on a multidisciplinary approach that combines cascade and pHstat leaching tests with solid phase characterization through X-ray diffraction (XRD), field emission gun electron probe micro analysis (FEG-EPMA), and thermodynamic modeling (Visual MinteQ 3.0). Solid phase characterization and thermodynamic modeling results allow prediction of Ni and Zn leachabilities. FEG-EPMA is useful for direct solid phase characterization because it provides information on additional phases including specific element associations that cannot be detected by XRD analysis. Cascade and pHstat leaching test results indicate that disposal of improperly treated sludges at landfills may lead to extreme environmental risks due to high leachable concentrations of Zn, Ni, Cu, Cr, and Pb. However, high leachabilities under acid conditions of Ni and Zn as observed from pHstat leaching test results may provide a potential opportunity for acid extraction recovery of Ni and Zn from such sludges.

  1. Difference of contrast enhancement characteristics of hepatic hemangiomas according to lesion size on two-phase spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Sung Hye; Yoon, Suk Kwon; Yang, Dal Mo; Yoon, Myung Hwan; Kim, Hak Soo; Kim, Hyung Sik; Chung, Jin Woo [Chungang Gil Hospital, Incheon (Korea, Republic of)

    1998-06-01

    The purpose of this study is to determine the different of enhancement patterns of hepatic hemangioma according to the lesion size, using dual-phase spiral CT. Fifty-nine lesions in 45 patients with hepatic hemangiomas were subjected to spiral CT. According to size, the lesions were divided into two groups (<2.5 cm : n=34;> {>=} 2.5 cm : n=25). The enhancement patterns of the lesions were classified as one of four types (homogeneous hyperdense, peripheral hyperdense, central hyperdense, peripheral hyperdense, central hyperdense, or hypodense) during the early phase, and as one of five types (homogeneous hyperdense, peripheral hyperdense, central hyperdense, hypodense of isodense) during the delayed phase. We evaluated differences in enhancement patterns during the early and delayed phase according to lesion size. During the early phase, the enhancement patterns of lesions large than 2.5 cm were peripheral hyperdense (96%) or homogeneous hyperdense (4%); those of less than 2.5 cm were peripheral hyperdense (53%), homogenous hyperdense (26%), hypodense (18%), or central hyperdense (3%). Thus, hemangiomas in these two groups usually showed a peripheral enhancement patterns were more common. During the delayed phase, the enhancement patterns of lesions larger than 2.5 cm were peripheral hyperdense (3%), or isodense (3%). Thus, the enhancement patterns of lesions larger than 2.5 cm showed a homogeneous enhancement pattern. The enhancement patterns of hepatic hemangiomas differ according to lesion size. A knowledge of these differences is helpful in the diagnosis of hepatic hemangioma. (author). 16 refs., 2 tabs., 3 figs.

  2. The fabrication of quantum wires in silicon utilising the characteristics of solid phase epitaxial regrowth of crystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liu, A.C.Y.; McCallum, J.C. [Melbourne Univ. Parkville, VIC (Australia). School of Physics, Microanalytical Research Centre

    1998-06-01

    The process of solid phase epitaxy (SPE) in semiconductor materials is one which has been intensively researched due to possible applications in the semiconductor industry. SPE is a solid phase transformation, in which an amorphous layer can be recrystallized either through heating or a combination of heating and ion bombardment. The transformation is believed to occur exclusively at the interface between the amorphous and crystalline layers, with individual atoms from the amorphous phase being incorporated into the crystalline phase by some point defect mechanism. The process has been observed to follow an Arrhenius temperature dependence. A wafer silicon was subjected to a multi-energy silicon implant through a fine nickel grid to amorphise region to a depth of 5{mu}m creating an array of amorphous wells. Metal impurity atoms were then implanted in this region at energy of 500 keV. Samples were examined using an optical microscope and the Alphastep profiler at RMIT. It was confirmed that burgeoning wells were about 2 {mu}m wide and rose about 0.01 {mu}m above the silicon substrate. Extended abstract. 4 refs., 3 figs.

  3. Appearance of large crystalline domains in VO{sub 2} films grown on sapphire (001) and their phase transition characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Azhan, Nurul Hanis; Su, Kui; Okimura, Kunio, E-mail: okifn@keyaki.cc.u-tokai.ac.jp [Graduate School of Science and Technology, Tokai University, Hiratsuka 259-1292 (Japan); Zaghrioui, Mustapha; Sakai, Joe [GREMAN, UMR 7347 CNRS, Université François Rabelais de Tours, Parc de Grandmont 37200 Tours (France)

    2015-06-28

    We report the first observation of large crystalline domains of several μm-size in VO{sub 2} films deposited on Al{sub 2}O{sub 3} (001) substrates by rf-biased reactive sputtering technique. The large crystalline domains, dominated with random in-plane oriented growth of (011){sub M1}-orientation, appear only under adequate substrate biasing, such as 10 W, while most biasing conditions result in conventional nanosized grains of highly oriented (010){sub M1}-orientation. Two temperature-controlled analyses, x-ray diffraction and micro-Raman spectroscopy, have revealed that some parts of large crystalline domains undergo intermediate monoclinic (M2) phase during the thermally-induced structural phase transition from monoclinic (M1) to rutile-tetragonal (R) phase. As an effect of the appearance of large crystalline domains, the film showed in-plane tensile stress, resulting in high T{sub IMT} of 69 °C due to the elongation of the V-V distance in its low-temperature monoclinic phase.

  4. A contribution to better understanding of structural characteristics and tectonic phases of the Boč region, Periadriatic Fault Zone

    Directory of Open Access Journals (Sweden)

    Lea Žibret

    2016-12-01

    Full Text Available The aim of this study was to determine properties of the tectonic contact between Permian/Mesozoic limestones and less competent Miocene clastites on the northeastern foothill of the Boč Mt. Because fault planes signifiantly mark the relief, this contact was studied by a detailed structural mapping, which showed that the Boč Mt. is limited by subvertical faults in its northeastern part. To ensure that mapped subvertical contact is compatible with regional geodynamics of the area, additionally paleostress analysis of fault-slip data was performed. Four individual paleostress tensor groups were documented in a wider Boč area and compared by published structural data from the border zone between Alps, Dinarides and Pannonian Basin. The oldest paleostress tensor group (Phase 1 is likely of Lower and Middle Miocene age and indicates SW-NE extension accommodated by W-E to WNW-ESE striking normal faults. Phase 2 can be correlated with Middle to Late Miocene NW-SE to WNWESE directed extension accommodated by NNE-SSW striking normal faults. Phase 3 is correlated with Late Miocene W-E directed contraction accommodated by N-S striking sinistral faults and NNE-SSW to NE-SW striking dextral faults. The youngest paleostress tensor group (Phase 4 fis well with Pliocene to Quaternary NNW-SSE to N-S directed contraction accommodated by NW-SE to W-E striking dextral faults and NE-SW striking reverse faults. Since the documented paleostress phases fis well with the geodynamic processes of the Alps-Dinarides-Carpathians territory the subvertical border in the northeastern part of Boč Mt. seems to be an acceptable structural solution. The study is important because the study area is located at interaction zone between two major Alpine fault systems: the Periadriatic and the Lavanttal faults.

  5. Microstructural characteristics and second-phase particles in yttrium-bearing Fe-10Ni-7Mn martensitic steels

    Institute of Scientific and Technical Information of China (English)

    F. Forghani; M. Nili-Ahmadabadi

    2014-01-01

    In this study, the microstructure and second-phase particles in yttrium (0.05 wt.%and 0.8 wt.%) bearing Fe-10Ni-7Mn steels were characterized. The results of X-ray analysis as well as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy indicated the formation of (Fe, Ni, Mn)17Y2 precipitates with hexagonal structure in a Fe-10Ni-7Mn-0.8Y (wt.%) alloy. Lattice parameters of these precipitates were calculated as follows:a=0.8485 nm and c=0.8274 nm. Formation of Y2O3 sub-micron particles was also confirmed in both yttrium bearing steels via electrolytic phase extraction method. The effect of these precipitates on the prior austenite grain size was investigated. The results revealed that these precipitates had an effective role in controlling the prior austenite grain size.

  6. An Experimental Study on the Flow Characteristics of OilWater Two-Phase Flow in Horizontal Straight Pipes

    Institute of Scientific and Technical Information of China (English)

    刘文红; 郭烈锦; 吴铁军; 张西民

    2003-01-01

    The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superficial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2 m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution ofoil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

  7. Performance characteristics of a suite of volume phase holographic gratings produced for the Subaru prime focus spectrograph

    Science.gov (United States)

    Arns, James A.

    2016-08-01

    The Subaru Prime Focus Spectrograph[1] (PFS) requires a suite of volume phase holographic (VPH) gratings that parse the observational spectrum into three sub-spectral regions. In addition, the red region has a second, higher resolution arm that includes a VPH grating that will eventually be incorporated into a grism. This paper describes the specifications of the four grating types, gives the theoretical performances of diffraction efficiency for the production designs and presents the measured performances on the gratings produced to date.

  8. Local Gas Phase Flow Characteristics of a Gas-Liquid-Solid Three-Phase Reversed Flow Jet Loop Reactor%气-液-固三相下喷环流反应器局部气相流动特性

    Institute of Scientific and Technical Information of China (English)

    闻建平; 周怀; 陈云琳

    2002-01-01

    The local gas-phase flow characteristics such as local gas holdup (εs), local bubble velocity (Vb) and local bubble mean diameter (db) at a specified point in a gas-liquid-solid three-phase reversed flow jet loop reactor was experimentally investigated by a five-point conductivity probe. The effects of gas jet flow rate, liquid jet flow rate, solid loading, nozzle dianeter and axial position on the local εg, Vb and db profiles were discussed. The presence of solids at low solid concentrations not only increased the local eg and Vb, but also decreased the local db. The optimum solid loading for the maximum local εg and Vb together with the minimum local db was 0.16 × 10-3 m3,corresponding to a solid volume fraction, εs = 2.5%.

  9. the Characteristic Phase Transitions of Co-doped BaFe2 As2 Synthesized via Flux Growth

    Science.gov (United States)

    Shea, C. H.; Roncaioli, C.; Eckberg, C.; Drye, T.; Sulliavan, M. C.; Paglione, J.

    2015-03-01

    Since the discovery of a new family of type II superconductors in 2008, the iron pnictides, researches have had suspicions that they might bear similar electronic properties to the well-known (but not easily understood) oxide superconductors. For this reason studies on this family of compounds has been of great interest to the materials science community. Our efforts have been aimed at single crystal growth and measurement of a particular member of this family, BaFe2As2. While this material is not superconducting at standard pressure, the partial substitution of cobalt on the iron site has been shown to suppresses an anti-ferromagnetic phase transition occurring at lower temperatures allowing for the appearance of a superconducting phase. Transport and low field magnetization measurements taken on our samples show clean transitions, indicating Tc's of up to 24 K in optimally doped samples. We will discuss the growth methods and temperature dependent phase transitions of this material at different cobalt concentrations. This work was supported by NSF Grant DMR-1305637.

  10. "Burst-like" Characteristics of the delta/alpha-prime Phase Transformation in Pu-Ga Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blobaum, K; Krenn, C; Haslam, J; Wall, M; Schwartz, A

    2003-11-10

    The {delta} to {alpha}' phase transformation in Pu-Ga alloys is intriguing for both scientific and technological reasons. On cooling, the ductile fcc d-phase transforms martensitically to the brittle monoclinic {alpha}'-phase at approximately -120 C (depending on composition). This exothermic transformation involves a 20% volume contraction and a significant increase in resistivity. The reversion of {alpha}' to {delta} involves a large temperature hysteresis beginning just above room temperature. In an attempt to better understand the underlying thermodynamics and kinetics responsible for these unusual features, we examined the {delta}/{alpha}' transformations in a 0.6 wt% Pu-Ga alloy using differential scanning calorimetry (DSC) and resistometry. Both techniques indicate that the martensite start temperature is -120 C and the austenite start temperature is 35 C. The heat of transformation is approximately 3 kJ/mole. During the {alpha}' {yields} {delta} reversion, ''spikes'' and ''steps'' are observed in DSC and resistometry scans, respectively. These spikes and steps are periodic, and their periodicity with respect to temperature does not vary with heating rate. With an appropriate annealing cycle, including a ''rest'' at room temperature, these spikes and steps can be reproduced through many thermal cycles of a single sample.

  11. Visualization and Pathological Characteristics of Hepatic Alveolar Echinococcosis with Synchrotron-based X-ray Phase Sensitive Micro-tomography

    Science.gov (United States)

    Liu, Huiqiang; Ji, Xuewen; Sun, Li; Xiao, Tiqiao; Xie, Honglan; Fu, Yanan; Zhao, Yuan; Liu, Wenya; Zhang, Xueliang; Lin, Renyong

    2016-11-01

    Propagation-based phase-contrast computed tomography (PPCT) utilizes highly sensitive phase-contrast technology applied to X-ray micro-tomography, especially with the extensive use of synchrotron radiation (SR). Performing phase retrieval (PR) on the acquired angular projections can enhance image contrast and enable quantitative imaging. We employed the combination of SR-PPCT and PR for the histopathological evaluation of hepatic alveolar echinococcosis (HAE) disease and demonstrated the validity and superiority of PR-based SR-PPCT. A high-resolution angular projection data set of a human postoperative specimen of HAE disease was acquired, which was processed by graded ethanol concentration fixation (GECF). The reconstructed images from both approaches, with the projection data directly used and preprocessed by PR for tomographic reconstruction, were compared in terms of the tissue contrast-to-noise ratio and density spatial resolution. The PR-based SR-PPCT was selected for microscale measurement and the 3D visualization of HAE disease. Our experimental results demonstrated that the PR-based SR-PPCT technique is greatly suitable for the discrimination of pathological tissues and the characterization of HAE. In addition, this new technique is superior to conventional hospital CT and microscopy for the three-dimensional, non-destructive microscale measurement of HAE. This PR-based SR-PPCT technique has great potential for in situmicroscale histopathological analysis and diagnosis, especially for applications involving soft tissues and organs.

  12. An adaptive, dose-finding, seamless phase 2/3 study of a long-acting glucagon-like peptide-1 analog (dulaglutide): trial design and baseline characteristics.

    Science.gov (United States)

    Geiger, Mary Jane; Skrivanek, Zachary; Gaydos, Brenda; Chien, Jenny; Berry, Scott; Berry, Donald

    2012-11-01

    Dulaglutide (dula, LY2189265) is a once-weekly glucagon-like peptide-1 analog in development for the treatment of type 2 diabetes mellitus. An adaptive, dose-finding, inferentially seamless phase 2/3 study was designed to support the development of this novel diabetes therapeutic. The study is divided into two stages based on two randomization schemes: a Bayesian adaptive scheme (stage 1) and a fixed scheme (stage 2). Stage 1 of the trial employs an adaptive, dose-finding design to lead to a dula dose-selection decision or early study termination due to futility. If dose selection occurs, the study proceeds to stage 2 to allow continued evaluation of the selected dula doses. At completion, the entire study will serve as a confirmatory phase 3 trial. The final study design is discussed, along with specifics pertaining to the actual execution of this study and selected baseline characteristics of the participants.

  13. Magnetic targeting in the impermeable microvessel with two-phase fluid model--non-Newtonian characteristics of blood.

    Science.gov (United States)

    Shaw, Sachin; Murthy, P V S N

    2010-09-01

    The present investigation deals with finding the trajectories of the drug dosed magnetic carrier particle in a microvessel with two-phase fluid model which is subjected to the external magnetic field. The radius of the microvessel is divided into the endothelial glycocalyx layer in which the blood is assumed to obey Newtonian character and a core and plug regions where the blood obeys the non-Newtonian Herschel-Bulkley character which is suitable for the microvessel of radius 50 microm. The carrier particles, bound with nanoparticles and drug molecules are injected into the vascular system upstream from malignant tissue, and captured at the tumor site using a local applied magnetic field. The applied magnetic field is produced by a cylindrical magnet positioned outside the body and near the tumor position. The expressions for the fluidic force for the carrier particle traversing in the two-phase fluid in the microvessel and the magnetic force due to the external magnetic field are obtained. Several factors that influence the magnetic targeting of the carrier particles in the microvasculature, such as the size of the carrier particle, the volume fraction of embedded magnetic nanoparticles, and the distance of separation of the magnet from the axis of the microvessel are considered in the present problem. An algorithm is given to solve the system of coupled equations for trajectories of the carrier particle in the invasive case. The trajectories of the carrier particle are found for both invasive and noninvasive targeting systems. A comparison is made between the trajectories in these cases. Also, the present results are compared with the data available for the impermeable microvessel with single-phase fluid flow. Also, a prediction of the capture of therapeutic magnetic nanoparticle in the impermeable microvasculature is made for different radii, distances and volume fractions in both the invasive and noninvasive cases.

  14. A result on the acoustic characteristics of the Mixture of Counter-phase Counteract and Split-gas Rushing muffler

    Directory of Open Access Journals (Sweden)

    Shao Ying-li

    2016-01-01

    Full Text Available The exhaust noise, which falls into low-frequency noise, is the dominant noise source of a diesel engines and tractors. The traditional exhaust silencers, which are normally constructed by combination of expansion chamber, and perforated pipe or perforated board, are with high exhaust resistance, but poor noise reduction especially for the low-frequency band noise. For this reason, a new theory of exhaust muffler of diesel engine based on counter-phase counteracts has been proposed. The mathematical model and the corresponding experimental validation for the new exhaust muffler based on this theory were performed.

  15. NiMn/FeNi exchange biasing systems-magnetic and structural characteristics after short annealing close to the phase transition point of the AFM layer

    Energy Technology Data Exchange (ETDEWEB)

    Groudeva-Zotova, S. E-mail: s.zotova@ifw-dresden.de; Elefant, D.; Kaltofen, R.; Thomas, J.; Schneider, C.M

    2004-07-01

    This work addresses the issue of acceleration of the long post-deposition annealing procedures typically used for obtaining the antiferromagnetic (AFM) state of the pinning film in NiMn-based spin-valve systems. It presents results on exchange biasing (EB) bi-layers NiMn(50 nm)/Ni{sub 19}Fe{sub 81}(5 nm) grown on a permalloy seed layer after annealing for a very short time at temperatures in the vicinity of the phase transition of the NiMn film. Both the magnetic and the structural characteristics measured after the short annealing procedure reveal clear differences between the samples annealed below and above a specific temperature T* which is lower than the phase transition temperature in the equilibrium NiMn phase diagram. The absence of an EB in the samples short annealed at T{sub an}phase. In contrast, the significant EB effect in the samples annealed at T{sub an}>T* and the saturation found in H{sub EB} for T{sub an}{>=}375 deg. C are connected with the existence of a dominant stable face centered tetragonal (FCT) AFM NiMn phase. This shows that for the investigated sputter-deposited NiMn pinning films a specific temperature T* exists above which a fast FCC implies FCT (paramagnetic implies AFM) phase transition occurs. The unidirectional EB effect surprisingly found in samples cooled without magnetic field can be explained with a two-step generation model: (i) the formation of specific magnetic anisotropy in the as-deposited permalloy films strongly depending on the phase composition of the NiMn pinning film, on its surface morphology and the stresses in the AFM/FM interface, respectively, and (ii) recording ('burning in') of the existing magnetic anisotropy through the described fast paramagnetic implies AFM phase transition.

  16. Study of the Composition and Spectral Characteristics of a HDG-Prism Disperse System (GRISM) by Refractive Index Phase Matching

    CERN Document Server

    Jo, Chon-Gyu; Im, Song-Jin

    2015-01-01

    The composition and characteristics of a GRISM gained by refractive index matching between a refractive index modulation type HDG and a prism is investigated, the HDG being built by processing silver halide emulsion with halide vapor. The GRISM has been stable under external influences like humidity or ultraviolet light exposure. The mercury atomic spectrum obtained by a GRISM based on a HDG with a spatial frequency of 600mm-1 shows yellow dual lines with the wavelength difference of 2.1nm sufficiently separated.

  17. Molecular dynamics study on the effect of boundary heating rate on the phase change characteristics of thin film liquid

    Science.gov (United States)

    Hasan, Mohammad Nasim; Morshed, A. K. M. Monjur; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    In this study, theoretical investigation of thin film liquid phase change phenomena under different boundary heating rates has been conducted with the help of molecular dynamics simulation. To do this, the case of argon boiling over a platinum surface has been considered. The study has been conducted to get a better understanding of the nano-scale physics of evaporation/boiling for a three phase system with particular emphasis on the effect of boundary heating rate. The simulation domain consisted of liquid and vapor argon atoms placed over a platinum wall. Initially the whole system was brought to an equilibrium state at 90K with the help of equilibrium molecular dynamics and then the temperature of the bottom wall was increased to a higher temperature (250K/130K) over a finite heating period. Depending on the heating period, the boundary heating rate has been varied in the range of 1600×109 K/s to 8×109 K/s. The variations of argon region temperature, pressure, net evaporation number with respect to time under different boundary heating rates have been determined and discussed. The heat fluxes normal to platinum wall for different cases were also calculated and compared with theoretical upper limit of maximum possible heat transfer to elucidate the effect of boundary heating rate.

  18. Difference in the Clinical Characteristics of Ventricular Fibrillation Occurrence in the Early Phase of an Acute Myocardial Infarction Between Patients With and Without J Waves.

    Science.gov (United States)

    Naruse, Yoshihisa; Nogami, Akihiko; Harimura, Yoshie; Ishibashi, Mayu; Noguchi, Yuichi; Sekiguchi, Yukio; Sato, Akira; Aonuma, Kazutaka

    2015-08-01

    We recently showed that the presence of J waves increases the risk of ventricular fibrillation (VF) occurrence in the early phase of an acute myocardial infarction (AMI). This study aimed to evaluate the clinical characteristics of VF occurrences in the early phase of an AMI between patients with and without J waves. This retrospective, observational study included 281 consecutive patients with an AMI (69 ± 12 years; 207 men) in whom 12-lead ECGs before AMI onset could be evaluated. The patients were classified based on a VF occurrence waves. J waves were electrocardiographically defined as an elevation of the terminal portion of the QRS complex of >0.1 mV from baseline in at least 2 contiguous inferior or lateral leads. VF occurred in 24 patients, and J waves were present in 37. VF occurrence was more prevalent in the patients with than without J waves (27% vs. 6%; P waves, peak creatine kinase level (P waves, there was no significant difference in these variables. There was no association between the location of J waves and the infarct area. In patients with AMI, those with J waves were more likely to develop VF and less likely to have high-risk clinical characteristics than those without J waves. © 2015 Wiley Periodicals, Inc.

  19. 智利地震震相特征分析%Analyzing the characteristics of seismic phase of earthquakes in Chile

    Institute of Scientific and Technical Information of China (English)

    林胜法; 金巧荣

    2011-01-01

    对智利地震在温州地震台的记录特征进行分析,对分析方法做阐述.其结论是:可清晰记录智利地震衍射波PDIF震相;PDIF震相波形“孤立”,起始平缓,周期较大;利用PDIF、PKP、SKKS、SS等明显震相的到时进行大震速报,可提高大震速报的速度和质量.%In this assay, the recording characteristics of earthquakes in Chile recorded by Wenzhou Seismic Station is analyzed, and the analytical method is also introduced in detail. It is found that if the epicentral distance of earthquakes in Chile equals 168 degree, the diffracted waves of PDIF seismic phase can still be recorded clearly. The recorded characteristics of the waves turn out to be single with gentle slope in the beginning and long period. Using the arriving time of obvious seismic phase such as PDIF, PKP,SKKS,SS to report the earthquakes rapidly is helpful to improve speed and quality of rapid reporting.

  20. Single phase flow characteristics of FC-72 and ethanol in high aspect ratio rectangular mini- and micro-channels

    Science.gov (United States)

    Wang, Yuan; Wang, Zhen-guo

    2016-11-01

    Single phase flow friction factor of FC-72 and ethanol in mini-and micro-channels are experimentally investigated in the present study. High aspect ratio3 rectangular channels are selected, the hydraulic diameters of which are 571 µm, 762 µm and 1454 µm, and the aspect ratios are 20, 20 and 10 respectively. Degassed ethanol and FC-72 are used as working fluids. All the friction factors acquired in the 571 µm and 762 µm channels agree with the conventional friction theory within  ±20%-±25%. In the 1454 µm channel, however, deviations from the conventional theory occur and a modified empirical correlation of friction factor as a function of Reynolds number is proposed. Early transition from laminar to transitional flow is captured. Besides, effects of liquid physical properties are discussed. Lower viscosity and higher liquid density are responsible for the higher friction factor of FC-72. The influence of liquid properties weakens as the Reynolds number increases.

  1. [Characteristics of the acute phase reaction in humans with various types of autonomic nervous system regulation during simulated hyperthermia].

    Science.gov (United States)

    Bannikov, A V; Dorofeĭkov, V V; Freĭdlin, T S; Freĭdlin, I S; Shustov, E B; Shcherbak, I G; Iastrebov, D Iu

    2000-01-01

    Depending on the type of autonomous regulation, differences in basic levels of interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) were revealed under conditions of hyperthermia in healthy subjects aged 19-21. A parasympathetic type of autonomous regulation corresponded to higher initial levels of proinflammatory cytokinesis, whereas a dominating sympathetic type corresponded to lower levels of the IL-1 beta and TNF alpha. The subjects with the latter type of regulation revealed an increase in the IL-1 beta TNF alpha combined with a higher heat tolerance. The subjects with the former type of regulation revealed a lower heat tolerance. The increase in the alpha2-macroglobulin appeared to be a most typical acute phase response of the human body to hyperthermia.

  2. Phase characteristics of rare earth elements in metallic fuel for a sodium-cooled fast reactor by injection casting

    Science.gov (United States)

    Kuk, Seoung Woo; Kim, Ki Hwan; Kim, Jong Hwan; Song, Hoon; Oh, Seok Jin; Park, Jeong-Yong; Lee, Chan Bock; Youn, Young-Sang; Kim, Jong-Yun

    2017-04-01

    Uranium-zirconium-rare earth (U-Zr-RE) fuel slugs for a sodium-cooled fast reactor were manufactured using a modified injection casting method, and investigated with respect to their uniformity, distribution, composition, and phase behavior according to RE content. Nd, Ce, Pr, and La were chosen as four representative lanthanide elements because they are considered to be major RE components of fuel ingots after pyroprocessing. Immiscible layers were found on the top layers of the melt-residue commensurate with higher fuel slug RE content. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) data showed that RE elements in the melt-residue were distributed uniformly throughout the fuel slugs. RE element agglomeration did not contaminate the fuel slugs but strongly affected the RE content of the slugs.

  3. Characteristics of stimulated emission from optically pumped freestanding GaN grown by hydride vapor-phase epitaxy

    CERN Document Server

    Lee, M H; Kim, S T; Chung, S H; Moon, D C

    1999-01-01

    In this study, we observed optically pumped stimulated emission at room temperature in quasi-bulk GaN prepared from thick-film GaN grown on a sapphire substrate by using hydride vapor-phase epitaxy and subsequent mechanical removal of the sapphire substrate. The stimulated emission from the surface and 1-mm-wide-cleaved cavity of the GaN was red-shifted compared to the spontaneous emission by increasing the optical pumping-power density, and the full width at half maximum (FWHM) of the peak decreased. The stimulated emission was demonstrated to have a highly TE-mode polarized nature, and the super-linear dependence of the integrated emission intensity on the excitation power indicated a threshold pump-power density of I sub t sub h = 2 MW/cm sup 2 for one set of stimulated emissions.

  4. Characteristics of Sn-Doped Ge2Sb2Te5 Films Used for Phase-Change Memory

    Institute of Scientific and Technical Information of China (English)

    XU Cheng; LIU Bo; SONG Zhi-Tang; FENG Song-Lin; CHEN Bomy

    2005-01-01

    @@ Sn-doped Ge2Sb2 Te5 thin films deposited on Si(100)/SiO2 substrates by rf magnetron sputtering are investigatedby a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystallizationtemperatures of the 3.58 at. %, 6.92 at. % and 10.04 at. % Sn-doped Ge2Sb2 Te5 thin films have decreases of 5.3,6.1 and 0.9 ℃, respectively, which is beneficial to reduce the switching current for the amorphous-to-crystallinephase transition. Due to Sn-doping, the sheet resistance of crystalline Ge2Sb2 Te5 thin films increases about 2-10times, which may be useful to reduce the switching current for the amorphous-to-crystalline phase change. Inaddition, an obvious decreasing dispersibility for the sheet resistance of Sn-doped Ge2Sb2 Te5 thin films in thecrystalline state has been observed, which can play an important role in minimizing resistance difference for thephase-change memory cell element arrays.

  5. Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

    Directory of Open Access Journals (Sweden)

    Siti Khadijah Hubadillah

    2016-06-01

    Full Text Available In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A and 10–15 μm (denoted as type B, at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. The support was prepared using kaolin type A induced asymmetric structure by combining macroporous voids and sponge-like structure in the support with pore size of 0.38 μm and 1.05 μm, respectively, and exhibited ideal porosity (27.7%, great mechanical strength (98.9 MPa and excellent gas permeation. Preliminary study shows that the kaolin ceramic support in this work is potential to gas separation application at lower cost.

  6. Adsorption characteristics of adsorbent resins and antioxidant capacity for enrichment of phenolics from two-phase olive waste.

    Science.gov (United States)

    Wang, Zhihong; Wang, Chengzhang; Yuan, Jiaojiao; Zhang, Changwei

    2017-01-01

    In this study, the adsorption properties of nine resins including polyamide resin (30-60), polyamide resin (60-100) AB-8, S-8, D-101, NKA-9, NKA-II, XDA-1 and XDA-4 for enrichment phenolics of the olive waste were investigated. XDA-1 and NKA-II were chosen for further study due to their outstanding adsorption and desorption capacity. XDA-1 and NKA-II had similar adsorption and desorption behaviors for phenolics of olive waste. The adsorption mechanism could be better explained by pseudo second-order kinetics model and Freundlich isotherm model, and the adsorption processes were spontaneously and exothermic. The experiment of gradient elution were carried out through treated XDA-1 resins column, the result indicated the total phenolics were mainly obtained from the 40% and 60% ethanol fraction. The order of antioxidant capacity by DPPH  , ABTS(+) radical and FRAP assay was similar with the content of phenolics from fraction elution. The compositions of phenolics from different elution fractions were determined by reversed phase-HPLC-DAD method. Gallic acid, hydroxytyrosol, tyrosol and ferulic acid were the major constituent in the fraction elute, and the content of hydroxytyrosol reached to the 41.69mg/g. The above results revealed the synergistic effects of the different phenolics contribute to the antioxidant capacity.

  7. Performance characteristics of two automated solid-phase red cell adherence systems for pretransfusion antibody screening: a cautionary tale.

    Science.gov (United States)

    Quillen, K; Caron, J; Murphy, K

    2012-01-01

    Out institution has implemented two instruments, the Galileo and the Echo, that use different solid-phase red cell adherence assays for antibody screening in pretransfusion compatibility testing.During the initial implementation of these two instruments, we noticed very different problems: falsely positive results on the Galileo, and falsely negative results and lack of reproducibility on the Echo. Comparison of falsely positive antibody screen results from approximately equivalent numbers of samples run on the Galileo and samples tested by standard manual tube technique using low-ionic-strength saline enhancement showed a false-positive rate of 1.4 percent on the Galileo (defined as a positive screen with a negative panel). Testing using the Echo identified four cases of falsely negative antibody screens, (defined as a negative screen on a patient sample subsequently shown to be positive by the same method). In addition, we note a lack of reproducibility on the Echo, which emphasizes the importance of replicate testing during validation of automated antibody screening platforms.

  8. Comparison of Y-jet and OIL effervescent atomizers based on internal and external two-phase flow characteristics

    Directory of Open Access Journals (Sweden)

    Mlkvik Marek

    2016-01-01

    Full Text Available Presented paper focuses on spraying of two viscous liquids (μ = 60 and 143 mPa·s by two types of twinfluid atomizers with internal mixing. We compared the well-known Y-jet atomizer with the less known, “outside in liquid” (OIL, configuration of the effervescent atomizer. The required liquid viscosity was achieved by using the water-maltodextrin solutions of different concentrations. Both the liquids were sprayed at two gas inlet pressures (Δp = 0.14 and 0.28 MPa and various gas-to-liquid ratios (GLR = 2.5%, 5%, 10% and 20%. The comparison was focused on four characteristics: liquid flow-rate (for the same working regimes, defined by Δp and GLR, internal flow regimes, Weber numbers of a liquid breakup (We and droplet sizes. A high-speed camera and Malvern Spraytec laser diffraction system were used to obtain necessary experimental data. Comparing the results of our experiments, we can state that for both the liquids the OIL atomizer reached higher liquid flow-rates at corresponding working regimes, it was typical by annular internal flow and higher We in the near-nozzle region at all the working regimes. As a result, it produced considerably smaller droplets than the second tested atomizing device, especially for GLR < 10%.

  9. Removal characteristics and kinetic analysis of an aerobic vapor-phase bioreactor for hydrophobic alpha-pinene

    Institute of Scientific and Technical Information of China (English)

    Yifeng Jiang; Shanshan Li; Zhuowei Cheng; Runye Zhu; Jianmeng Chen

    2012-01-01

    Biofiltration is considered an effective method to control volatile organic compounds(VOCs)pollution.This study was conducted to evaluate the potential use of a bacterial biofilter packed with wood chips and peat for the removal of hydrophobic α-pinene.When inoculated with two pure degraders and adapted activated sludge,a removal efficiency(RE)of more than 95% was achieved after a start-up period of 11 days.The maximum elimination capacity(EC)of 50 g/(m3?hr)with RE of 94% was obtained at empty bed retention time (EBRT) of 102 sec.When higher α-pinene concentrations and shorter EBRTs were applied,the REs and ECs decreased significantly due to mass-transfer and biological reaction limitations.As deduced from the experimental results,approximately 74% of α-pinene were completely mineralized by the consortiums and the biomass yield was 0.60 g biomass/g α-pinene.Sequence analysis of the selected bands excised from denaturing gradient gel electrophoresis revealed that the inoculated pure cultures could be present during the whole operation,and others were closely related to bacteria being able to degrade hydrocarbons.The kinetic results demonstrated that the whole biofiltration for α-pinene was diffusion-limit controlled owing to its hydrophobic characteristics.These findings indicated that this bacterial biofiltration is a promising technology for the remediation of hydrophobic industrial waste gases containing α-pinene.

  10. Ni3Ta合金的微观组织结构和相变特性%Microstructure and Phase Transformation Characteristics of Ni3Ta Alloy

    Institute of Scientific and Technical Information of China (English)

    罗渝; 杨水源; 王翠萍; 刘兴军

    2012-01-01

    Microstructure and phase transformation characteristics of Ni3Ta alloy were investigated by optical microscope (OM), back-scattered electron (BSE), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microscope (TEM). The results show that the Ni3Ta alloy, which was annealed at 1 200 C for 4 h,consists of monoclinic Ni3Ta phase,tetragonal Ni3Ta phase and a little amount of Ni2Ta phase. Monoclinic Ni3Ta phase shows the microstructure of hair-like stripes with a width of about 0. 1-0. 3 μm, which exhibits typical twin structure with a twinning plane (001). This strict twinned martensite micro-structure is beneficial to the reversibility of thermoelastic martensitic transformation, which makes Ni3Ta alloy a promising SMA with an excellent SME. During heating and cooling process, there is a reversible phase transformation between monoclinic and tetragonal Ni3Ta phases with the transformation starting temperatures about 310 ℃ and 245 ℃ ,respectively. Moreover,during heating process there is another phase transformation from monoclinic to orthorhombic Ni3 Ta phase with the transformation starting temperature a-bout 310 C. But the orthorhombic phase generated during heating process still remains in the specimen after cooling.%采用光学显微镜、背散射电子图像、X射线衍射、电子探针、差示扫描量热法和透射电子显微镜研究了Ni2Ta合金的微观组织结构和相变特性.结果表明:Ni2Ta合金在经过1 200 C保温4h的热处理后,主要由大量Ni2Ta相和少量Ni2Ta析出相组成,其中Ni2Ta相有单斜和四方两种结构.单斜Ni2Ta相为典型的细小板条状马氏体形状,其板条宽度为0.1~0.3μm,且存在以(001)晶面为孪品面的典型孪品结构.Ni3Ta合金在升温和降温过程中存在单斜Ni2Ta相和四方Ni3Ta相的可逆相变,相变开始温度分别约为310和245℃.另外,在升温过程中还存在单斜Ni3Ta相向正交Ni3Ta相的转变,

  11. Familial Aggregation of Metabolic Syndrome With Different Socio-Behavioral Characteristics: The Fourth Phase of Tehran Lipid and Glucose Study.

    Science.gov (United States)

    Zarkesh, Maryam; Asghari, Golaleh; Amiri, Parisa; Hosseinzadeh, Nima; Hedayati, Mehdi; Ghanbarian, Arash; Azizi, Fereidoun

    2016-08-01

    Since genetic and most environmental factors shape the context of families, some studies have been initiated to investigate the role of familial relationships in metabolic syndrome (MetS). To estimate the familial aggregation of MetS and its components by identifying both case and control probands among Tehranian adults with different socio-behavioral and reproductive characteristics. This case-controlled/family-based study was conducted on 1,777 families (635 case probands) who participated in the Tehran Lipid and Glucose Study (TLGS). Socio-demographic and reproductive information including levels of education, marital status, occupation status, age at menarche, number of abortions, number of children, and lifestyle habits such as smoking, physical activity and regular diet were obtained from the TLGS data bank. Metabolic syndrome was defined according to the joint interim statement (JIS) criteria. To estimate the regression co-efficient for familial aggregation and environmental factors, the generalized estimation equation method was used. The risk of having MetS among family members for case versus control probands was 2.19 (95% CI: 1.68 - 2.84), which, after adjusting for potential confounders including age, sex, educational level, marital status, occupation, age at menarche and energy, soft drink and starchy vegetable intake, increased to 2.31 (95% CI: 1.81 - 2.94; P pressure (BP) to OR = 1.72 for high triglycerides in cases. Familial aggregation inherited from the father was significantly observed in all MetS components, from adjusted OR = 1.63 for hyperglycemia to adjusted OR = 2.69 for high WC, except for low HDL, after controlling for potential confounders. Considering spouses and siblings, there was a higher risk for MetS components among families whose fathers and offspring had MetS components, implying the pivotal role of genetic inheritance in the incidence of the syndrome and its components.

  12. Investigation of the characteristics of biofilms grown in gas-phase biofilters with and without ozone injection by CLSM technique.

    Science.gov (United States)

    Saingam, Prakit; Xi, Jinying; Xu, Yang; Hu, Hong-Ying

    2016-02-01

    Recently, ozone injection technique was developed as a novel biomass control method to reduce bed clogging in biofilters treating volatile organic compounds (VOCs). However, the effects of ozone on the characteristics of biofilms are still unknown. In this study, two identical lab-scale biofilters treating gaseous toluene were operated in parallel except that one was continuously injected with 200 mg/m(3) ozone. Four glass slides were placed inside each biofilter on day 57 and then were taken out sequentially after 1, 2, 4, and 6 weeks of cultivation. The biofilms grown on the glass slides were stained by the ViaGram™ Red + Bacterial Gram Stain and Viability Kit and observed through the confocal laser scanning microscopy (CLSM). According to the CLSM images of 1, 2, and 4 weeks, the ozonated biofilm was significantly thinner than the control biofilm, which demonstrated that ozone could effectively control the biomass in the biofilter. For the biofilter without ozone injection, the ratios of viable cells (0.51~0.89) and the ratios of Gram-positive bacteria (0.22~0.57) both decreased within 4 weeks of cultivation. The CLSM image analysis results also demonstrated that a continuous injection of 200 mg/m(3) ozone was able to significantly enhance the ratio of viable cells to 0.77~0.97 and allow the dominance of Gram-positive bacteria in the biofilms with the ratio 0.46~0.88 instead of Gram-negative bacteria. For the 6-week samples, the biofilm thickness of the control system was reduced significantly which indicated the detachment of accumulated biofilms might occur in the samples without ozone.

  13. Familial Aggregation of Metabolic Syndrome With Different Socio-Behavioral Characteristics: The Fourth Phase of Tehran Lipid and Glucose Study

    Science.gov (United States)

    Zarkesh, Maryam; Asghari, Golaleh; Amiri, Parisa; Hosseinzadeh, Nima; Hedayati, Mehdi; Ghanbarian, Arash; Azizi, Fereidoun

    2016-01-01

    Background Since genetic and most environmental factors shape the context of families, some studies have been initiated to investigate the role of familial relationships in metabolic syndrome (MetS). Objectives To estimate the familial aggregation of MetS and its components by identifying both case and control probands among Tehranian adults with different socio-behavioral and reproductive characteristics. Patients and Methods This case-controlled/family-based study was conducted on 1,777 families (635 case probands) who participated in the Tehran Lipid and Glucose Study (TLGS). Socio-demographic and reproductive information including levels of education, marital status, occupation status, age at menarche, number of abortions, number of children, and lifestyle habits such as smoking, physical activity and regular diet were obtained from the TLGS data bank. Metabolic syndrome was defined according to the joint interim statement (JIS) criteria. To estimate the regression co-efficient for familial aggregation and environmental factors, the generalized estimation equation method was used. Results The risk of having MetS among family members for case versus control probands was 2.19 (95% CI: 1.68 - 2.84), which, after adjusting for potential confounders including age, sex, educational level, marital status, occupation, age at menarche and energy, soft drink and starchy vegetable intake, increased to 2.31 (95% CI: 1.81 - 2.94; P < 0.05). Compared to control probands, the risk of having MetS components increased significantly from OR = 1.28 for both high waist circumference (WC) and blood pressure (BP) to OR = 1.72 for high triglycerides in cases. Familial aggregation inherited from the father was significantly observed in all MetS components, from adjusted OR = 1.63 for hyperglycemia to adjusted OR = 2.69 for high WC, except for low HDL, after controlling for potential confounders. Conclusions Considering spouses and siblings, there was a higher risk for MetS components

  14. Fabrication and characteristics of GaAs-AlGaAs tunable laser diodes with DBR and phase-control sections integrated by compositional disordering of a quantum well

    Science.gov (United States)

    Hirata, Takaaki; Maeda, Minoru; Suehiro, Masayuki; Hosomatsu, Haruo

    1991-06-01

    GaAs-AlGaAs rib-waveguide graded-index separate-confinement heterostructure (GRINSCH) single-quantum-well (SQW) tunable distributed Bragg reflector (DBR) laser diodes were fabricated by (EB) lithography, ion implantation, and two-step metalorganic vapor phase epitaxy (MOVPE) growth. Active and passive waveguides were monolithically integrated by the compositional disordering of quantum-well heterostructures using silicon ion implantation. First-order gratings and rib waveguides were adopted with EB lithography to improve lasing characteristics, and they have wide application to photonic integrated circuits (PICs). Waveguide losses of partially disordered GRINSCH-SQW passive waveguides were as low as 4.4/cm at the lasing wavelength. A narrow linewidth as low as 560 kHz and a frequency tuning of more than 2.9 THz were obtained. The results show that this fabrication process is useful for PICs.

  15. Reduced Subthreshold Characteristics and Flicker Noise of an AlGaAs/InGaAs PHEMT Using Liquid Phase Deposited TiO2 as a Gate Dielectric

    Directory of Open Access Journals (Sweden)

    Kai-Yuen Lam

    2016-10-01

    Full Text Available This study presents the fabrication and improved properties of an AlGaAs/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor (MOS-PHEMT using liquid phase deposited titanium dioxide (LPD-TiO2 as a gate dielectric. Sulfur pretreatment and postoxidation rapid thermal annealing (RTA were consecutively employed before and after the gate dielectric was deposited to fill dangling bonds and therefore release interface trapped charges. Compared with a benchmark PHEMT, the AlGaAs/InGaAs MOS-PHEMT using LPD-TiO2 exhibited larger gate bias operation, higher breakdown voltage, suppressed subthreshold characteristics, and reduced flicker noise. As a result, the device with proposed process and using LPD-TiO2 as a gate dielectric is promising for high-speed applications that demand little noise at low frequencies.

  16. [Investigation of characteristic microstructures of adhesive interface in wood/bamboo composite material by synchrotron radiation X-ray phase contrast microscopy].

    Science.gov (United States)

    Peng, Guan-Yun; Wang, Yu-Rong; Ren, Hai-Qing; Yang, Shu-Min; Ma, Hong-Xia; Xie, Hong-Lan; Deng, Biao; Du, Guo-Hao; Xiao, Ti-Qiao

    2013-03-01

    Third-generation synchrotron radiation X-ray phase-contrast microscopy(XPCM)can be used for obtaining image with edge enhancement, and achieve the high contrast imaging of low-Z materials with the spatial coherence peculiarity of X-rays. In the present paper, the characteristic microstructures of adhesive at the interface and their penetration in wood/bamboo composite material were investigated systematically by XPCM at Shanghai Synchrotron Radiation Facility (SSRF). And the effect of several processing techniques was analyzed for the adhesive penetration in wood/bamboo materials. The results show that the synchrotron radiation XPCM is expected to be one of the important precision detection methods for wood-based panels.

  17. Latent Heat storage characteristics of solid-liquid phase change Heat Storage Microcapsule Slurry by Boiling Heat Transfer under a Vacuum Condition

    Science.gov (United States)

    Inaba, Hideo; Horibe, Akihiko; Haruki, Naoto; Katayama, Masatoshi; Manabe, Ken

    Recently, the new heat transfer medium, which fulfills both functions of heat storage and heat transportation, has been developed in ah eat storage field. Solid-liquid latent heat microcapsule slurry would correspond to the topical medium, so-called functionally thermal fluid. The preset study has clarified the latent heat storage characteristics of microcapsule slurry by making heat transfer enlargement with the help of slurry water pool boiling phenomenon. The paraffin wax at a melting point of 62°C was used as a phase change material which was packed into the microcapsule. The heating surface temperature and concentration of paraffin in the microcapsule slurry was selected as experimental parameters. As a result, the non-dimensional correlation equations of heat storage completion time and heat transfer were derived in terms of non-dimensional parameters.

  18. Breakdown characteristics in pulsed-driven dielectric barrier discharges: influence of the pre-breakdown phase due to volume memory effects

    Science.gov (United States)

    Höft, H.; Kettlitz, M.; Becker, M. M.; Hoder, T.; Loffhagen, D.; Brandenburg, R.; Weltmann, K.-D.

    2014-11-01

    The pre-phase of the breakdown of pulsed-driven dielectric barrier discharges (DBDs) was investigated by fast optical and electrical measurements on double-sided DBDs with a 1 mm gap in a gas mixture of 0.1 vol% O2 in N2 at atmospheric pressure. Depending on the pulse width (the pause time between subsequent DBDs), four different breakdown regimes of the following discharge were observed. By systematically reducing the pulse width, the breakdown characteristics could be changed from a single cathode-directed propagation (positive streamer) to simultaneous cathode- and anode-directed propagations (positive and negative streamer) and no propagation at all for sub-μs pulse times. For all cases, different spatio-temporal emission structures in the pre-phase were observed. The experimental results were compared with time-dependent, spatially one-dimensional fluid model calculations. The modelling results confirmed that different pre-ionisation conditions, i.e. considerably high space charges in the volume created by the residual electrons and ions from the previous discharge, are the reason for the observed phenomena.

  19. Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

    Institute of Scientific and Technical Information of China (English)

    WEI Chao-hai; WANG Wen-xiang; DENG Zhi-yi; WU Chao-fei

    2007-01-01

    A new anaerobic reactor,Jet-loop anaerobic fluidized bed(JLAFB),was designed for treating high-sulfate wastewater.The treatment characteristics,including the effect of influent COD/SO42- ratio and alkalinity and sulfide inhibition in reactors,were discussed for a JLAFB and a general anaerobic fluidized bed(AFB)reactor used as sulfate-reducing phase and methane-producing phase,respectively,in two-phase anaerobic digestion process.The formation of granules in the two reactors was also examined.The results indicated that COD and sulfate removal had different demand of influent COD/S042- ratios.When total COD removal Was up to 85%,the ratio was only required up to 1.2,whereas,total sulfate removal up to 95%required it exceeding 3.0.The alkalinity in the two reactors increased linearly with the growth of influent alkalinity.Moreover,the change of influent alkalinity had no significant effect on pH and volatile fatty acids(VFA)in the two reactors.Influent alkalinity kept at 400-500 mg/t,could meet the requirement of the treating process.The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms.When sulfate loading rate was up to 8.1 kg/(m3·d),the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L,respectively.Furthermore,the granules,with offwhite color,ellipse shape and diameters of 1.0-3.0 mm,could be developed in JLAFB reactor.In granules,different groups of bacteria were distributed in different layers,and some inorganic metal compounds such as Fe,Ca,Mg etc.were found.

  20. Phase-field modeling of switchable diode-like current-voltage characteristics in ferroelectric BaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y., E-mail: yxc238@psu.edu; Randall, C. A.; Chen, L. Q. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Shen, J. [Department of Mathematics, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-05-05

    A self-consistent model has been proposed to study the switchable current-voltage (I-V) characteristics in Cu/BaTiO{sub 3}/Cu sandwiched structure combining the phase-field model of ferroelectric domains and diffusion equations for ionic/electronic transport. The electrochemical transport equations and Ginzburg-Landau equations are solved using the Chebyshev collocation algorithm. We considered a single parallel plate capacitor configuration which consists of a single layer BaTiO{sub 3} containing a single tetragonal domain orientated normal to the plate electrodes (Cu) and is subject to a sweep of ac bias from −1.0 to 1.0 V at 25 °C. Our simulation clearly shows rectifying I-V response with rectification ratios amount to 10{sup 2}. The diode characteristics are switchable with an even larger rectification ratio after the polarization direction is flipped. The effects of interfacial polarization charge, dopant concentration, and dielectric constant on current responses were investigated. The switchable I-V behavior is attributed to the polarization bound charges that modulate the bulk conduction.

  1. A modified phase coherence model for the non-linear c-axis V-I characteristics of highly anisotropic, high temperature superconductors

    CERN Document Server

    Luo Sheng; Huang Sai Jun; He Yu Sheng; Li Chun Guang; Zhang Xue Qiang

    2003-01-01

    A modified Ambegaokar-Halperin thermal-fluctuation model has been developed to describe the c-axis V-I characteristics and low-current ohmic resistance of highly anisotropic superconductors in a magnetic field parallel to the c-axis. The model assumes loss of phase coherence across the CuO-planes associated with the correlated motion of pancake vortices in the liquid state. The predicted V-I characteristics in the current-induced transition from the superconducting to the resistive state are in good agreement with measurements on a 2212-BSCCO single crystal as a function of temperature and field, provided the effect of the interlayer capacitance is taken into account. The measurements are consistent with a flux pancake correlation length within the CuO-planes varying as xi sub 0 /(T/T sub 0 - 1) supnu, where xi sub 0 = 1.57 +- 0.08 mu m and nu = 0.50 +- 0.01. Our measurements imply a current-dependent interlayer resistance above and below T sub c.

  2. COMPARISON OF CHARACTERISTICS OF THE CONVERTER-FED MOTOR AT SUPPLY FROM THE SINGLE-PHASE NETWORK AND FROM THE SOURCE OF THE DIRECT CURRENT

    Directory of Open Access Journals (Sweden)

    V.B. Finkelshtein

    2015-08-01

    Full Text Available Purpose. Now even more often in various cars and mechanisms converter-fed motors are used. Their comparative characteristics with motors which are supplied from a network of a direct current are necessary for definition of the specific moment of motors which are supplied from the single-phase alternating current main. Methodology. For the converter-fed motor with a ratio of teeth of the stator and a rotor 8/6 at supply from a single-phase network via the rectifier two groups of numerical experiments were carried out. Motor capacity with a constant frequency of rotation at various capacity of the capacitor at the exit of the rectifier and motor capacity at the current providing the most admissible excess of temperature of a winding are determined. Dependences of useful power on capacity size at the rectifier exit are received with a constant frequency of rotation, and also at invariable current. Results. On the basis of the made numerical experiment it is possible to conclude that due to fluctuation of tension (from 0 to 100 % at the rectifier exit at power supply of the converter-fed motor from the single-phase alternating current main in comparison with the corresponding sizes at supply from a source of a direct current: • motor capacity at preservation of capacity of the capacitor at the exit of the rectifier and frequency of rotation decreases on 60 – 63 %; • at almost acceptable increase in capacity of the capacitor (approximately twice power should be reduced by 50 %; • power deceleration at preservation of that size of current of the motor what took place at its food from a source of a direct current makes 40 % at preservation of size of capacity of the capacitor at the exit of the rectifier and 32 % at its doubling, the frequency of rotation decreases approximately on 13 – 15 %. Practical value. The specific moment can be determined by power sizes at single-phase supply, frequency of rotation and to the volume of a rotor, with

  3. Two-phase flow characteristics of liquid nitrogen in vertically upward 0.5 and 1.0 mm micro-tubes: Visualization studies

    Science.gov (United States)

    Zhang, P.; Fu, X.

    2009-10-01

    Application of liquid nitrogen to cooling is widely employed in many fields, such as cooling of the high temperature superconducting devices, cryosurgery and so on, in which liquid nitrogen is generally forced to flow inside very small passages to maintain good thermal performance and stability. In order to have a full understanding of the flow and heat transfer characteristics of liquid nitrogen in micro-tube, high-speed digital photography was employed to acquire the typical two-phase flow patterns of liquid nitrogen in vertically upward micro-tubes of 0.531 and 1.042 mm inner diameters. It was found from the experimental results that the flow patterns were mainly bubbly flow, slug flow, churn flow and annular flow. And the confined bubble flow, mist flow, bubble condensation and flow oscillation were also observed. These flow patterns were characterized in different types of flow regime maps. The surface tension force and the size of the diameter were revealed to be the major factors affecting the flow pattern transitions. It was found that the transition boundaries of the slug/churn flow and churn/annular flow of the present experiment shifted to lower superficial vapor velocity; while the transition boundary of the bubbly/slug flow shifted to higher superficial vapor velocity compared to the results of the room-temperature fluids in the tubes with the similar hydraulic diameters. The corresponding transition boundaries moved to lower superficial velocity when reducing the inner diameter of the micro-tubes. Time-averaged void fraction and heat transfer characteristics for individual flow patterns were presented and special attention was paid to the effect of the diameter on the variation of void fraction.

  4. Experimental study on the effects of surface gravity waves of different wavelengths on the phase averaged performance characteristics of marine current turbine

    Science.gov (United States)

    Luznik, L.; Lust, E.; Flack, K. A.

    2014-12-01

    There are few studies describing the interaction between marine current turbines and an overlying surface gravity wave field. In this work we present an experimental study on the effects of surface gravity waves of different wavelengths on the wave phase averaged performance characteristics of a marine current turbine model. Measurements are performed with a 1/25 scale (diameter D=0.8m) two bladed horizontal axis turbine towed in the large (116m long) towing tank at the U.S. Naval Academy equipped with a dual-flap, servo-controlled wave maker. Three regular waves with wavelengths of 15.8, 8.8 and 3.9m with wave heights adjusted such that all waveforms have the same energy input per unit width are produced by the wave maker and model turbine is towed into the waves at constant carriage speed of 1.68 m/s. This representing the case of waves travelling in the same direction as the mean current. Thrust and torque developed by the model turbine are measured using a dynamometer mounted in line with the turbine shaft. Shaft rotation speed and blade position are measured using in in-house designed shaft position indexing system. The tip speed ratio (TSR) is adjusted using a hysteresis brake which is attached to the output shaft. Free surface elevation and wave parameters are measured with two optical wave height sensors, one located in the turbine rotor plane and other one diameter upstream of the rotor. All instruments are synchronized in time and data is sampled at a rate of 700 Hz. All measured quantities are conditionally sampled as a function of the measured surface elevation and transformed to wave phase space using the Hilbert Transform. Phenomena observed in earlier experiments with the same turbine such as phase lag in the torque signal and an increase in thrust due to Stokes drift are examined and presented with the present data as well as spectral analysis of the torque and thrust data.

  5. 零相差跟踪控制器增益特性处理技术%Gain-characteristics manipulation technique for zero phase error tracking controller

    Institute of Scientific and Technical Information of China (English)

    周黎; 杨世洪; 高晓东

    2012-01-01

    In a zero phase error tracking control system, the gain error increases as frequency increases; meanwhile, the zero phase error tracking control system exhibits amplification to high frequency noises. In order to solve these problems, a gain-characteristics manipulation method for zero phase error tracking controller is investigated based on the idea of op- timization. By setting the optimization objective function and restriction conditions, we design the gain error compensator with gain-compensation in low frequency band and gain-attenuation in high frequency band. The design process is given in details and the parameter calculation formulas are derived analytically. Simulation results indicate that the designed compensator effectively increases the tracking accuracy and reduces noise content in controller output, thus, improving the motion smoothness and providing advantages for engineering applications.%零相差跟踪控制系统增益误差随频率升高而增大,同时零相差跟踪控制器对高频噪声有放大作用.为了解决以上问题,本文研究了一种对零相差跟踪控制器增益特性的处理方法.采用了求解优化问题的思想,通过对优化目标函数及约束条件的设置,使设计得到的补偿器具有低频段增益误差补偿,高频段增益衰减的性能.文中详细介绍了补偿器的设计过程,理论推导了参数计算公式.比较仿真结果表明,所设计的补偿器有效地提高了轨迹跟踪精度,减小了控制器输出噪声含量,有利于提高运动平稳性,对工程实践具有参考价值.

  6. Characteristics of Acoustic Field of Two-dimensional Ultrasonic Phased Array%二维超声相控阵的声场特性

    Institute of Scientific and Technical Information of China (English)

    龙绒蓉; 王海涛; 郭瑞鹏; 徐君; 郭艳; 沈立军

    2015-01-01

    基于空间冲激响应的脉冲声场模型及超声相控阵指向性理论,使用 MATLAB 仿真软件,分析了二维矩形阵列各参数对其声场特性的影响,据此推导出阵列探头设计、选取的一般准则;对比研究二维矩形阵列和圆形阵列的脉冲回波声场。结果表明,圆形阵列具有更窄的主瓣宽度和更低的第一级旁瓣,更优的指向性。%Based on the pulsed ultrasonic field model of the space impulse response and the directivity theory of ultrasonic phased array,the effect of two-dimensional rectangular array parameters on the acoustical characteristics was investigated by using MATLAB simulation software.Accordingly,the general guidelines of array probe design and selection was derived.Comparative studies were also carried on the pulse-echo acoustic field of two-dimensional rectangular array and circular array,showing that the circular array had a narrower width of main lobe and lower first side lobe,etc,so the performance of the latter being more outstanding.

  7. Structural and waveguiding characteristics of Er3+:Yb3Al5-yGayO12 films grown by the liquid phase epitaxy

    Science.gov (United States)

    Hlásek, T.; Rubešová, K.; Jakeš, V.; Nekvindová, P.; Kučera, M.; Daniš, S.; Veis, M.; Havránek, V.

    2015-11-01

    Erbium (Er3+) doped ytterbium garnet (Er:Yb3Al5-yGayO12; y = 0, 0.55 and 1.1) single crystalline thick films have been grown by the low-temperature liquid phase epitaxy method (LPE). The composition of the films was determined using the high resolution XRD, the particle-induced X-ray emission spectroscopy (PIXE) and the particle-induced gamma-ray emission spectroscopy (PIGE). The lattice mismatch between films and substrates was investigated by the high-resolution X-ray diffraction. The surface analysis was carried out by the atomic force microscopy (AFM). Pure infrared emission of Er3+ ions was observed in all films containing gallium. The characteristics such as refractive index, thickness and light propagation were studied by the m-line spectroscopy (MLS) using several wavelengths (633, 964, 1311 and 1552 nm). All samples, where y = 1.1, were multimode waveguides. For these reasons, the Er:Yb3Al3.9Ga1.1O12 seems to be a promising material for light amplifiers in the IR region.

  8. Observation on characteristics of floral differentiation and development of sweet cherry in late phase%甜樱桃花芽分化后期特征观察

    Institute of Scientific and Technical Information of China (English)

    赵长竹; 姜建福; 张慧琴; 李淑平; 顾红; 林苗苗; 谢鸣; 方金豹

    2012-01-01

    In order to grope for the mechanism in fruiting problem of sweet cherry (Prunus avium L. ) in southern areas of China, three experiments, including variety comparison, location comparison and artifi- cial environmental simulation, had been carried out from the stage of post-defoliation to the stage of post- bloom for observation of the characteristics of differentiation and development of floral bud of sweet cherry. The results showed that the floral bud of sweet cherry had ultimately displayed the basic characteristics of differentiation and development in identity at the phases of multi-phenological calendars in the stages mentioned above in those tested varieties which were Zaohongbaoshi, Hongdeng and Lapins cultured in Zhengzhou, and Hongdeng cultured in Yantai, Zhengzhou, and Jinhua, and Zaohongbaoshi cultured in openfield and greenhouse in the period of floral bud differentiation in those three experimental designs. It was argued that the mechanism of fruiting difficulty mentioned above had no relationship with the floral bud differentiation in growth season, and not only the embryo sac in poorly developmental quality which was induced by high temperature before the stage of post-bloom but laso the shortage of chilling accumu- lation should be responsible for the fruiting difficulty.%通过品种比较、地区比较和人工环境模拟3个关联的试验设计,观察甜樱桃从落叶后至谢花后的花芽分化发育的特征,探求其南引试栽、结实困难的原因。结果表明,郑州的早红宝石、红灯和拉宾斯.烟台、郑州和金华的红灯,以及花芽分化期置于露地和日光温室中的早红宝石在多个物候期阶段的最终分化发育的基本特征一致。因此。造成甜樱桃南引试栽、结实困难的主要原因可能与生长季的花芽分化无关,不能仅限于与花前高温引发的胚珠、胚囊发育不良有关,低温累积量不足也是不可被忽视的因素。

  9. Mixed phases during the phase transitions

    CERN Document Server

    Tatsumi, Toshitaka; Maruyama, Toshiki

    2011-01-01

    Quest for a new form of matter inside compact stars compels us to examine the thermodynamical properties of the phase transitions. We closely consider the first-order phase transitions and the phase equilibrium on the basis of the Gibbs conditions, taking the liquid-gas phase transition in asymmetric nuclear matter as an example. Characteristic features of the mixed phase are figured out by solving the coupled equations for mean-fields and densities of constituent particles self-consistently within the Thomas-Fermi approximation. The mixed phase is inhomogeneous matter composed of two phases in equilibrium; it takes a crystalline structure with a unit of various geometrical shapes, inside of which one phase with a characteristic shape, called "pasta", is embedded in another phase by some volume fraction. This framework enables us to properly take into account the Coulomb interaction and the interface energy, and thereby sometimes we see the mechanical instability of the geometric structures of the mixed phase...

  10. Photocatalytic characteristics of single phase Fe-doped anatase TiO{sub 2} nanoparticles sensitized with vitamin B{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Gharagozlou, Mehrnaz, E-mail: gharagozlou@icrc.ac.ir [Department of Nanomaterials and Nanotechnology, Institute for Color Science and Technology, Tehran (Iran, Islamic Republic of); Bayati, R. [Intel Corporation, IMO-SC, SC2, Santa Clara, CA 95054 (United States)

    2015-01-15

    Highlights: • Anatase TiO{sub 2}/B{sub 12} hybrid nanostructured catalyst was successfully synthesized by sol–gel technique. • The nanoparticle catalyst was doped with iron at several concentrations. • Nanoparticles were characterized in detail by XRD, Raman, TEM, EDS, and spectroscopy techniques. • The formation mechanism and role of point defects on photocatalytic properties were discussed. • A structure-property-processing correlation was established. - Abstract: We report a processing-structure-property correlation in B{sub 12}-anatase titania hybrid catalysts doped with several concentrations of iron. Our results clearly show that low-level iron doping alters structure, defect content, and photocatalytic characteristics of TiO{sub 2}. XRD and Raman studies revealed formation of a single-phase anatase TiO{sub 2} where no iron based segregation in particular iron oxide, was detected. FT-IR spectra clearly confirmed sensitization of TiO{sub 2} nanoparticles with vitamin B{sub 12}. TEM micrographs and diffraction patterns confirmed crystallization of anatase nanoparticles with a radius of 15–20 nm. Both XRD and Raman signals showed a peak shift and a peak broadening which are surmised to originate from creation of point defects, namely oxygen vacancy and titanium interstitial. The doped samples revealed a narrower band gap as compared to undoped samples. Photocatalytic activity of the samples was assessed through measuring the decomposition rate of rhodamine B. It was found that sensitization with vitamin B{sub 12} and Fe-doping significantly enhances the photocatalytic efficiency of the anatase nanoparticles. We also showed that there is an optimum Fe-doping level where the maximum photocatalytic activity is achieved. The boost of photocatalytic activity was qualitatively understood to originate from a more effective use of the light photons, formation of point defects, which enhance the charge separation, higher carrier mobility.

  11. Preliminary construction of integral analysis for characteristic components in complex matrices by in-house fabricated solid-phase microextraction fibers combined with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Tang, Zhentao; Hou, Wenqian; Liu, Xiuming; Wang, Mingfeng; Duan, Yixiang

    2016-08-26

    Integral analysis plays an important role in study and quality control of substances with complex matrices in our daily life. As the preliminary construction of integral analysis of substances with complex matrices, developing a relatively comprehensive and sensitive methodology might offer more informative and reliable characteristic components. Flavoring mixtures belonging to the representatives of substances with complex matrices have now been widely used in various fields. To better study and control the quality of flavoring mixtures as additives in food industry, an in-house fabricated solid-phase microextraction (SPME) fiber was prepared based on sol-gel technology in this work. The active organic component of the fiber coating was multi-walled carbon nanotubes (MWCNTs) functionalized with hydroxyl-terminated polydimethyldiphenylsiloxane, which integrate the non-polar and polar chains of both materials. In this way, more sensitive extraction capability for a wider range of compounds can be obtained in comparison with commercial SPME fibers. Preliminarily integral analysis of three similar types of samples were realized by the optimized SPME-GC-MS method. With the obtained GC-MS data, a valid and well-fit model was established by partial least square discriminant analysis (PLS-DA) for classification of these samples (R2X=0.661, R2Y=0.996, Q2=0.986). The validity of the model (R2=0.266, Q2=-0.465) has also approved the potential to predict the "belongingness" of new samples. With the PLS-DA and SPSS method, further screening out the markers among three similar batches of samples may be helpful for monitoring and controlling the quality of the flavoring mixtures as additives in food industry. Conversely, the reliability and effectiveness of the GC-MS data has verified the comprehensive and efficient extraction performance of the in-house fabricated fiber.

  12. A three-phase epidemiological study of short and long sleepers in a middle-aged Chinese population: prevalence and characteristics

    Directory of Open Access Journals (Sweden)

    Y.L. Hao

    2014-02-01

    Full Text Available Epidemiological studies of short and long sleepers have not been conducted previously. We collected socioeconomic, psychological, and polysomnographic characteristics of 6501 parents (3252 men and 3249 women of 4036 primary school children in Guangzhou city. The study data were collected in three phases. The overall prevalence of short (5 h or less and long (10 h or more sleep duration was 0.52 and 0.64%, respectively. Long sleepers had higher Eysenck Personality Questionnaire neuroticism scores [odds ratio (OR=1.224, 95% confidence interval (CI=1.047-1.409] and lower education levels (OR=0.740, 95%CI=0.631-0.849 than short sleepers. In the polysomnographic assessment, short, long, and normal sleepers (7-8 h shared similar durations of Stage 3 sleep (short=25.7±10.7, long=20.3±7.9, and normal=28.0±12.8 min, F=1.402, P=0.181. In daytime multiple sleep latency tests, short sleepers (10/19, 52.6% were more prone to have a short sleep latency (≤8 min than long sleepers (2/23, 8.7%. In addition to different sleep durations, neuroticism might also contribute to differences between short and long sleepers in social achievements. Stage 3 sleep might be essential for humans. The short sleep latency (≤8 min of short sleepers in multiple sleep latency tests should be interpreted cautiously, since it was of the same severity as required for a diagnosis of narcolepsy or idiopathic hypersomnia.

  13. A three-phase epidemiological study of short and long sleepers in a middle-aged Chinese population: prevalence and characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Y.L. [Department of Human Anatomy, Guangzhou Medical University, Guangzhou, China, Department of Human Anatomy, Guangzhou Medical University, Guangzhou (China); Zhang, B.; Jia, F.J.; Li, X.L.; Tang, Y. [Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangdong Mental Health Centre, Guangzhou, China, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangdong Mental Health Centre, Guangzhou (China); Ren, Y.Z. [Zhongshan The Third People' s Hospital, Zhongshan, China, Zhongshan The Third People' s Hospital, Zhongshan (China); Liu, W.H. [Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangdong Mental Health Centre, Guangzhou, China, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangdong Mental Health Centre, Guangzhou (China)

    2014-02-17

    Epidemiological studies of short and long sleepers have not been conducted previously. We collected socioeconomic, psychological, and polysomnographic characteristics of 6501 parents (3252 men and 3249 women) of 4036 primary school children in Guangzhou city. The study data were collected in three phases. The overall prevalence of short (5 h or less) and long (10 h or more) sleep duration was 0.52 and 0.64%, respectively. Long sleepers had higher Eysenck Personality Questionnaire neuroticism scores [odds ratio (OR)=1.224, 95% confidence interval (CI)=1.047-1.409] and lower education levels (OR=0.740, 95%CI=0.631-0.849) than short sleepers. In the polysomnographic assessment, short, long, and normal sleepers (7-8 h) shared similar durations of Stage 3 sleep (short=25.7±10.7, long=20.3±7.9, and normal=28.0±12.8 min, F=1.402, P=0.181). In daytime multiple sleep latency tests, short sleepers (10/19, 52.6%) were more prone to have a short sleep latency (≤8 min) than long sleepers (2/23, 8.7%). In addition to different sleep durations, neuroticism might also contribute to differences between short and long sleepers in social achievements. Stage 3 sleep might be essential for humans. The short sleep latency (≤8 min) of short sleepers in multiple sleep latency tests should be interpreted cautiously, since it was of the same severity as required for a diagnosis of narcolepsy or idiopathic hypersomnia.

  14. Impact of co-landfill proportion of bottom ash and municipal solid waste composition on the leachate characteristics during the acidogenesis phase.

    Science.gov (United States)

    He, Pin-Jing; Pu, Hong-Xia; Shao, Li-Ming; Zhang, Hua

    2017-08-14

    Incineration has become an important municipal solid waste (MSW) treatment strategy, and generates a large amount of bottom ash (BA). Although some BA is reused, much BA and pretreatment residues from BA recycling are disposed in landfill. When BA and MSW are co-landfilled together, acid neutralization capacity and alkaline earth metal dissolution of BA, as well as different components of MSW may change environmental conditions within the landfill, so the degradation of organic matter and the physical and chemical properties of leachate would be affected. In this study, the effect of co-landfilled BA and MSW on the leachate characteristics during the hydrolysis and acidogenesis phase was studied using different BA/MSW ratios and MSW compositions. The results showed that the co-landfill system increased leachate pH, electric conductivity and alkalinity. For MSW with a high content of degradable components, the release and degradation of total organic carbon (TOC) and volatile fatty acids (VFA) from MSW were promoted when the BA ratio by wet weight was less than 50%, and the biodegradability of leachate was improved. When the BA ratio exceeded 50%, the degradation of organic matters was inhibited. For MSW with low content of degradable components, when the proportion of BA was less than 20%, the release and degradation of TOC and VFA from MSW were promoted and alkalinity increased. When the BA ratio exceeded 20%, the degradation of organic matters was inhibited. The 50% BA ratio could improve the bio-treatability of leachate indicated by the leachate pH and C/N ratio. However, BA inhibited the release of nitrogen (TN and NH4(+)-N) at all BA ratios and MSW compositions. At the same time, the addition of BA increased the risk of leachate collection system clogging due to the dissolution and re-precipitation of alkaline earth metals contained in BA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. The Effect of Calcium and Available Phosphorus Levels on Performance, Egg Quality and Bone Characteristics of Japanese Quails at End of the Egg-Production Phase

    Directory of Open Access Journals (Sweden)

    CLN Ribeiro

    Full Text Available ABSTRACT Calcium (Ca and available phosphorus (avP requirements for egg production are different between the beginning and the end of the egg-production cycle. The objective of this study was to estimate the Ca and avP requirements of Japanese quails at end of the production phase. In total, 256 Japanese quails with 48 weeks of age were randomly distributed in 2 x 2 factorial arrangement consisting of two Ca levels (29 and 38 g/kg and two avP levels (1.5 and 3.0 g/kg, totaling four treatments with eight replicates of eight hens each. The variables evaluated were feed intake (FI; egg production (EP; marketable egg production (MEP; egg weight (EW; egg mass (EM; feed conversion ratio per egg mass (FCRM; feed conversion ratio per dozen eggs (FCRD; livability (L; yolk weight (YW, albumen weight (AW, eggshell weight (SW; yolk percentage (YP, albumen percentage (AP, eggshell percentage (SP, specific egg weight (SEW; bone calcium percentage (BCa, bone phosphorus percentage (BP, bone ash weight (Bash and bone ash percentage (PBash. There was no interaction between Ca and avP levels for any of the evaluated parameters, except for SEW. Quail performance was not influenced by the treatments, except for MEP. Bone characteristics were not influenced by the tested dietary Ca and avP levels. However, SW and SP increased and AP decreased as dietary Ca level increased. The dietary supplementation of 38 g Ca/kg and 3.0 g avP/kg may increase marketable egg production and the egg quality of Japanese quails at end of the production cycle.

  16. Phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Wei; Mao, Chaoliang; Liu, Zhen; Dong, Xianlin; Cao, Fei; Wang, Genshui, E-mail: genshuiwang@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2015-03-02

    The phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} lead-free ceramics were investigated systematically. The loss tangent of poled sample shows a broad peak when heating to about 80 °C, i.e., depolarization temperature T{sub d}. The polarization-electric field hysteresis loops at different temperature exhibit the feature of ferroelectric (FE)- antiferroelectric (AFE) phase transition and the co-existence of FE and AFE phase. The pyroelectric coefficients curve confirms its diffusion behaviors. The initial hysteresis loop and switching current curves under T{sub d} indicate the co-existence of FE and AFE phase. The domain morphology of transmission electron microscopy supports the co-existence of FE and AFE phase. Our work not only exhibit that the FE and AFE phase characteristics of 0.92Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.08BiAlO{sub 3} ceramics but also they may be helpful for further investigation on lead-free ceramics.

  17. Phase Statistics of Soliton

    OpenAIRE

    Ho, Keang-Po

    2003-01-01

    The characteristic function of soliton phase jitter is found analytically when the soliton is perturbed by amplifier noise. In additional to that from amplitude jitter, the nonlinear phase noise due to frequency and timing jitter is also analyzed. Because the nonlinear phase noise is not Gaussian distributed, the overall phase jitter is also non-Gaussian. For a fixed mean nonlinear phase shift, the contribution of nonlinear phase noise from frequency and timing jitter decreases with distance ...

  18. Structure characteristics of cubic and orthorhombic phases of high density scintillator PbF{sub 2} from 4.2--300 K

    Energy Technology Data Exchange (ETDEWEB)

    Shmyt`ko, I.; Savchenko, I.B.; Klassen, N.V.; Bagautdinov, B.S.; Emel`chenko, G.A.; Sinitzin, V.V. [Russian Academy of Sciences, Chernogolovka (Russian Federation). Inst. of Solid State Physics

    1994-12-31

    An anomaly of the temperature dependence of the unit cell parameter has been observed for {beta}-PbF{sub 2} single crystals at 200 K that is interpreted as a phase transition to a pseudocubic lattice. Such a pseudocubic phase is observable at room temperature after uniaxial plastic deformation of the bulk single crystals. The structural aspects of the {beta}{r_arrow}{alpha} transition have been established. The as-grown crystals of {alpha}-PbF{sub 2} phase are shown to undergo a phase transition at 100 K.

  19. An impedance analyzer method to simulate the oscillating characteristic of a series piezoelectric sensor in oscillators with zero or non-zero phases.

    Science.gov (United States)

    Dazhong, S; Yuanjin, X; Lihua, N; Shouzhuo, Y

    1994-11-01

    An impedance analyzer method is employed to simulate the oscillation frequency of a series piezoelectric quartz crystal (SPQC) in electrolyte or non-electrolyte solutions. The influence of the oscillator phase on the oscillation frequency and response sensitivity are theoretically derived and experimentally verified. In non-electrolyte liquids, the oscillator phase has little effect on both the oscillation frequency and the response to the permittivity. But in electrolyte solutions, the oscillator phase has a significant influence on the oscillation frequency and the response sensitivity to the conductivity. Depending on the oscillator phase, the oscillation frequency of the SPQC may increase, be maintained or decrease with increasing conductivity in low or high conductive solutions. The dependence of the oscillation frequency of the SPQC on the supply voltage is explained. As an example of the applications, the SPQC is applied to the determination of the critical micelle concentration of ionic surfactants in aqueous solutions.

  20. Effect of Al content on the phase structure and the hydrogenation characteristic of La(Mg1-xAlx) alloys

    Institute of Scientific and Technical Information of China (English)

    HOU Qingyu; ZHANG Qing'an

    2006-01-01

    La(Mg1-xAlx) (x=0.2,0.4,0.6,0.8) alloys have been prepared using induction melting followed by annealing. It is found that partial substitution of Mg by Al does not lead to a change in crystal structure, and the alloys have a single LaMg phase when x ≤ 0.4. The lattice parameter of the LaMg phase decreases obviously after the partial substitution of Mg by Al. However, further substitution of Mg by Al leads to the coexistence of multiple phases when x ≥ 0.6. The alloys consist of the LaMg, LaAl, LaAl2, and La5Al4 phases. The LaMg phase decreases, whereas the La5Al4 phase increases with the increase in x. The Al-substituted La(Mg0.6Al0.4) alloy can be hydrogenated into the tetragonal LaH3, cubic LaH3, MgH2, and LaAl under 5 MPa at 473 K for 5 d.

  1. Poor Information Analysis on Rolling Bearing Vibration Characteristic Parameter Based on Phase Space%基于相空间的滚动轴承振动特征参数的乏信息分析

    Institute of Scientific and Technical Information of China (English)

    高磊磊; 夏新涛; 樊雎; 孙小超

    2011-01-01

    The original dynamics characteristics of roiling bearing vibration time series are restored by phase space reconstruction with chaos theory. The dynamical Bayesian posterior probability density function of bearing vibration characteristic parameter is constructed by maximum entropy bootstrap and Bayesian statistics in phase space. Finally, the methods about point estimation, interval estimation and trend estimation of characteristic parameter are proposed. The investigation shows that errors between inference results and experiment results are very small, and requirements in engineering are then satisfied. Therefore, the statistical characteristic of bearing vibration can be described using the proposed poor information mathematical model.%用混沌理论进行相空间重构,恢复轴承振动时间序列的原始动力学特征,然后在相空间里,用最大熵自助法并结合Bayes统计理论,建立轴承振动特征参数的动态Bayes后验概率密度函数,最后对特征参数进行点估计、区间估计及趋势估计等.试验研究表明,估计结果和试验结果在数值上很接近,满足工程要求.因此,用乏信息数学模型可以真实地评价轴承振动的统计特征.

  2. Characteristics of PVdF-HFP/TiO{sub 2} composite membrane electrolytes prepared by phase inversion and conventional casting methods

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwang Man; Ryu, Kwang Sun; Chang, Soon Ho [Ionics Devices Team, Basic Research Lab., Electronics and Telecommunications Research Institute (ETRI), 161 Gajong, Yusong, Daejon 305-700 (Korea, Republic of); Park, Nam-Gyu [Materials Science and Technology Division, Korea Institute of Science and Technology (KIST), 39-1 Hwaolgok, Seongbuk, Seoul 136-791 (Korea, Republic of)

    2006-08-15

    Porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer membranes filled with various contents of titania (TiO{sub 2}) nanocrystalline particles are prepared by phase inversion technique and, along with conventional casting method for comparison. N-methyl-2-pyrrolidone (NMP) as a solvent is used to dissolve the polymer and to make the slurry with TiO{sub 2}. Cast film is obtained by spreading the slurry and evaporating NMP in a dry oven, while phase inversion membrane by promptly immersing the spread slurry into flowing water as a non-solvent. Physical and electrochemical characterizations, such as morphology, thermal and crystalline behavior, and other transport properties of lithium ionic species, are carried out for the polymer films/membranes and the polymer electrolytes with absorbing an electrolyte solution. Phase inversion polymer electrolytes are proved to show superior behaviors in electrochemical properties, such as ionic conductivity, electrochemical and interfacial stability, than cast film electrolytes. This is greatly owed to highly porous structure of phase inversion membranes. Even including the feature of interfacial resistance with lithium electrode, phase inversion polymer electrolytes of PVdF-HFP/(5-20wt.% TiO{sub 2}) can be optimized as the adequate ones in applying to the electrolyte medium of lithium rechargeable batteries. (author)

  3. Fatigue crack propagation characteristics of ductile cast iron austempered from (. alpha. +. gamma. ) phase region. (. alpha. +. gamma. ) iki kara austemper shorishita kyujo kokuen chutetsu no hiro kiretsu shinten tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Y.; Asami, K.; Kuroiwa, H. (Musashi Institute of Technoloyg, Tokyo (Japan))

    1991-01-15

    In order to enhance the fatigue crack propagation resistance of ductile cast iron, the effect of austempering from a ({alpha} + {gamma}) phase region was studied. As the dual phase matrix microstructure of ferrite and pearlite in as-casted iron was changed into the dual phase one of ferrite and bainite by partial austempering from 800 {degree} C, the fatigue crack propagation resistance was enhanced over the whole range of a {Delta} K region. The enhancement of the fatigue crack propagation resistance was caused by remarkable development of crack closures from higher {Delta} K regions which was induced by fracture contact and fretting because of an increase in fracture roughness and easy formation of oxide deposits. In addition, the static tensile and ductility of ductile cast iron were possibly enhanced simultaneously by partial austempering for changing pearlite into bainite superior in both tensile and ductility. 9 refs., 13 figs., 3 tabs.

  4. Characterization of a New Phase and Its Effect on the Work Characteristics of a Near-Stoichiometric Ni30Pt20Ti50 High-Temperature Shape Memory Alloy (HTSMA)

    Science.gov (United States)

    Garg, A.; Gaydosh, D.; Noebe, R.D.; Padula II, Santo; Bigelow, G.S.; Kaufman, M.; Kovarik, L.; Mills, M.J.; Diercks, D.; McMurray, S.

    2008-01-01

    A new phase observed in a nominal Ni30Pt20Ti50 (at.%) high temperature shape memory alloy has been characterized using transmission electron microscopy and 3-D atom probe tomography. This phase forms homogeneously in the B2 austenite matrix by a nucleation and growth mechanism and results in a concomitant increase in the martensitic transformation temperature of the base alloy. Although the structure of this phase typically contains a high density of faults making characterization difficult, it appears to be trigonal (-3m point group) with a(sub o) approx. 1.28 nm and c(sub o) approx. 1.4 nm. Precipitation of this phase increases the microhardness of the alloy substantially over that of the solution treated and quenched single-phase material. The effect of precipitation strengthening on the work characteristics of the alloy has been explored through load-biased strain-temperature testing in the solution-treated condition and after aging at 500 C for times ranging from 1 to 256 hours. Work output was found to increase in the aged alloy as a result of an increase in transformation strain, but was not very sensitive to aging time. The amount of permanent deformation that occurred during thermal cycling under load was small but increased with increasing aging time and stress. Nevertheless, the dimensional stability of the alloy at short aging times (1-4 hours) was still very good making it a potentially useful material for high-temperature actuator applications.

  5. Phase transition characteristics and dielectric properties of rare-earth (La, Pr, Nd, Gd) doped Ba(Zr0.09Ti0.91)O-3 ceramics

    OpenAIRE

    2010-01-01

    A-site deficient rare-earth doped barium zirconate titanate (BZT) ceramics (Ba1−yLn2y/3)Zr0.09Ti0.91O3 (Ln = La, Pr, Nd, Gd) are obtained by a modified solid-state reaction method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples shows that the addition of rare-earth ions inhibits the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on phase transition and diel...

  6. The Behavior and Characteristics of the Interfacial Waves in Gas-Liquid Two-Phase Separated Flow Thorugh Downward Inclined Rectangular Channel

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    An Experimental investigation on the behavior and characteristics of interfacial waves in downward inclined rectangular channel was conducted.The interfacial waves were traced and measured by using conductance technique.The wave patterns were distingushed and defined.The characteristics of the interfacial waves.such as time-averaged film thickness,wave height,wave propagation speed,wavelength and wave frequency,were systematically examined in terms of gas and liquid superficial volumetric fluxes.The effect of the inclination and flow channel geometry of the test section on the interfacial wave was also investigated.

  7. Influence of fluid-mechanical characteristics of the system on the volumetric mass transfer coefficient and gas dispersion in three-phase system

    Directory of Open Access Journals (Sweden)

    Knežević Milena M.

    2014-01-01

    Full Text Available Distribution of gas bubbles and volumetric mass transfer coefficient, Kla, in a three phase system, with different types of solid particles at different operation conditions were studied in this paper. The ranges of superficial gas and liquid velocities used in this study were 0,03-0,09 m/s and 0-0,1 m/s, respectively. The three different types of solid particles were used as a bed in the column (glass dp=3 mm, dp=6 mm; ceramic dp=6 mm. The experiments were carried out in a 2D plexiglas column, 278 x 20,4 x 500 mm and in a cylindrical plexiglas column, with a diameter of 64 mm and a hight of 2000 mm. The Kla coefficient increased with gas and liquid velocities. Results showed that the volumetric mass transfer coefficient has a higher values in three phase system, with solid particles, compared with two phase system. The particles properties (diameter and density have a major impact on oxygen mass transfer in three phase systems.

  8. Follicular and luteal phase characteristics following early cessation of gonadotrophin-releasing hormone agonist during ovarian stimulation for in-vitro fertilization

    NARCIS (Netherlands)

    J.S.E. Laven (Joop); M.J.C. Eijkemans (René); B.C.J.M. Fauser (Bart); N.G.M. Beckers (Nicole)

    2000-01-01

    textabstractGonadotrophin-releasing hormone agonists (GnRHa) are widely used in in-vitro fertilization (IVF) for the prevention of a premature rise in luteinizing hormone (LH) concentrations. However, the administration of GnRHa during the follicular phase may also impa

  9. Development of Career Opportunities for Technicians in the Nuclear Medicine Field, Phase I. Interim Report Number 1: Survey of Job Characteristics, Manpower Needs and Training Resources, July 1969.

    Science.gov (United States)

    Technical Education Research Center, Cambridge, MA.

    Phase I of a multiphase research program in progress at the Technical Education Research Center, Inc., was conducted to analyze needs and resources in terms of job performance tasks, career opportunities, and training requirements for nuclear medical technicians. Data were gathered through personal interviews with 203 persons, mostly physicians,…

  10. Solution of dynamic characteristics of journal bearing based on two phase flow theory%基于两相流理论滑动轴承动力特性求解

    Institute of Scientific and Technical Information of China (English)

    孙丹; 张楚; 郭瑞; 杨建刚

    2012-01-01

    将计算流体动力学(CFD)两相流与动网格技术应用于滑动轴承动力特性数值求解,建立了基于CFD两相流滑动轴承动力特性求解模型,该模型无需设定油膜破裂边界条件且更能准确模拟滑动轴承流场特性.比较了单相流与两相流滑动轴承压力分布特性,计算分析了滑动轴承气穴分布特征及其影响因素,研究了两相流模型对滑动轴承动力特性的影响.计算结果表明:气化比例随着转速、偏心率和气化压力的增加而迅速增大,随进口压力的增加而缓慢减小.考虑两相流后,直接刚度系数增加,交叉刚度系数减小,直接与交叉阻尼系数均减小.随着偏心率的增加,单相流与两相流动力特性系数求解结果偏差增大.%The computational fluid dynamics(CFD) two phase flow and dynamic mesh technologies were applied to the numerical calculation of dynamic characteristics of journal bearing.A new journal bearing dynamic characteristic solving model using the two phase flow theory of CFD model was established.The two phase flow theory of computational fluid dynamics for the journal bearing dynamic characteristics did not need to define the oil film rupture boundary condition,and it can generate more complementary and more accurate flow information.The pressure distribution characteristics of the sliding bearing were compared,and the cavitation characteristics and the effects of the journal bearing were calculated.Finally,the effect of the two phase flow theory of CFD model on dynamic characteristics of journal bearing was analyzed.Calculation results show that the cavitation ratio increases significantly with the increase of rotating speed,eccentricity,and vaporization pressure,and decreases slowly with the increase of inlet pressure.Using two phase flow,calculation results also show that the direct stiffness increases,the cross stiffness decreases and the direct and cross dampings decrease.The deviation between the

  11. Employees’ Preferences for more or fewer Working Hours. The Effects of Usual, Contractual and Standard Working Time, Family Phase and Household Characteristics, and Job Satisfaction

    NARCIS (Netherlands)

    Tijdens, K.

    2002-01-01

    This study seeks explanations for working time preferences, using cross-sectional multinomial logits for the 2001/2002 Wage Indicator dataset (N=21,727). As expected, the preferences are predominately influenced by working hours’ characteristics, showing that employees with long hours prefer to work

  12. Employees’ Preferences for more or fewer Working Hours. The Effects of Usual, Contractual and Standard Working Time, Family Phase and Household Characteristics, and Job Satisfaction

    NARCIS (Netherlands)

    Tijdens, K.

    2002-01-01

    This study seeks explanations for working time preferences, using cross-sectional multinomial logits for the 2001/2002 Wage Indicator dataset (N=21,727). As expected, the preferences are predominately influenced by working hours’ characteristics, showing that employees with long hours prefer to work

  13. Phase contrast X-ray imaging for the non-invasive detection of airway surfaces and lumen characteristics in mouse models of airway disease

    Energy Technology Data Exchange (ETDEWEB)

    Siu, K.K.W. [School of Physics, Monash University, Victoria 3800 (Australia); Monash Centre for Synchrotron Science, Monash University, Victoria 3800 (Australia)], E-mail: Karen.Siu@sync.monash.edu.au; Morgan, K.S.; Paganin, D.M. [School of Physics, Monash University, Victoria 3800 (Australia); Boucher, R. [CF Research and Treatment Center, University of North Carolina at Chapel Hill (United States); Uesugi, K.; Yagi, N. [SPring-8/JASRI, Hyogo 679-5198 (Japan); Parsons, D.W. [Department of Pulmonary Medicine, Women' s and Children' s Hospital, South Australia 5006 (Australia); Department of Paediatrics, University of Adelaide, South Australia, 5006 (Australia); Women' s and Children' s Health Research Institute, South Australia, 5006 (Australia)

    2008-12-15

    We seek to establish non-invasive imaging able to detect and measure aspects of the biology and physiology of surface fluids present on airways, in order to develop novel outcome measures able to validate the success of proposed genetic or pharmaceutical therapies for cystic fibrosis (CF) airway disease. Reduction of the thin airway surface liquid (ASL) is thought to be a central pathophysiological process in CF, causing reduced mucociliary clearance that supports ongoing infection and destruction of lung and airways. Current outcome measures in animal models, or humans, are insensitive to the small changes in ASL depth that ought to accompany successful airway therapies. Using phase contrast X-ray imaging (PCXI), we have directly examined the airway surfaces in the nasal airways and tracheas of anaesthetised mice, currently to a resolution of {approx}2 {mu}m. We have also achieved high resolution three-dimensional (3D) imaging of the small airways in mice using phase-contrast enhanced computed tomography (PC-CT) to elucidate the structure-function relationships produced by airway disease. As the resolution of these techniques improves they may permit non-invasive monitoring of changes in ASL depth with therapeutic intervention, and the use of 3D airway and imaging in monitoring of lung health and disease. Phase contrast imaging of airway surfaces has promise for diagnostic and monitoring options in animal models of CF, and the potential for future human airway imaging methodologies is also apparent.

  14. Evaluation of mobile phase characteristics on three zwitterionic columns in hydrophilic interaction liquid chromatography mode for liquid chromatography-high resolution mass spectrometry based untargeted metabolite profiling of Leishmania parasites.

    Science.gov (United States)

    Zhang, Rong; Watson, David G; Wang, Lijie; Westrop, Gareth D; Coombs, Graham H; Zhang, Tong

    2014-10-03

    It has been reported that HILIC column chemistry has a great effect on the number of detected metabolites in LC-HRMS-based untargeted metabolite profiling studies. However, no systematic investigation has been carried out with regard to the optimisation of mobile phase characteristics. In this study using 223 metabolite standards, we explored the retention mechanisms on three zwitterionic columns with varied mobile phase composition, demonstrated the interference from poor chromatographic peak shapes on the output of data extraction, and assessed the quality of chromatographic signals and the separation of isomers under each LC condition. As expected, on the ZIC-cHILIC column the acidic metabolites showed improved chromatographic performance at low pH which can be attributed to the opposite arrangement of the permanently charged groups on this column in comparison with the ZIC-HILIC column. Using extracts from the protozoan parasite Leishmania, we compared the numbers of repeatedly detected LC-HRMS features under different LC conditions with putative identification of metabolites not amongst the standards being based on accurate mass (±3ppm). Besides column chemistry, the pH of the mobile phase plays a key role in not only determining the retention mechanisms of solutes but also the output of the LC-HRMS data processing. Fast evaporation of ammonium carbonate produced less ion suppression in ESI source and consequently improved the detectability of the metabolites in low abundance in comparison with other ammonium salts. Our results show that the combination of a ZIC-pHILIC column with an ammonium carbonate mobile phase, pH 9.2, at 20mM in the aqueous phase or 10mM in both aqueous and organic mobile phase components, provided the most suitable LC conditions for LC-HRMS-based untargeted metabolite profiling of Leishmania parasite extracts. The signal reliability of the mass spectrometer used in this study (Exactive Orbitrap) was also investigated.

  15. Analyzing the characteristics of phase-shift keyed signals applied to the measurement of an electron concentration profile using the radiophysical model of the ionosphere

    Science.gov (United States)

    Alsatkin, S. S.; Medvedev, A. V.; Kushnarev, D. S.

    2009-12-01

    The radiophysical model of the ionosphere, which can approximately imitate the ionospheric response to a sounding signal, is presented. The model mathematical description and input parameters are given. The results of modeling the ionospheric response to different types of sounding signals are presented. The methods for estimating the quality of restoration of an initial power profile are described. The optimal characteristics of the signal, which allows for a high-quality restoration of an initial power profile, and the modeling results are presented.

  16. Effect of the ionic strength of a mobile phase on the chromatographic retention and thermodynamic characteristics of the adsorption of enantiomers of α-phenylcarboxylic acids on a chiral adsorbent with grafted antibiotic eremomycin

    Science.gov (United States)

    Reshetova, E. N.

    2017-01-01

    The effect the ionic strength of an aqueous ethanol mobile phase containing buffer salt has the on retention and thermodynamics of adsorption of optical isomers of some α-phenylcarboxylic acids on chiral adsorbent Nautilus-E with grafted antibiotic eremomycin is investigated. It is shown that ion exchange processes participate in the adsorption of enantiomers of α-phenylcarboxylic acids. It is established that electrostatic interactions contribute to the retention of enantiomers of α-phenylcarboxylic acids and affect selectivity only slightly. The dependences of retention characteristics, selectivity, and thermodynamic parameters on the concentration of the buffer salt in the eluent are determined. A statistical analysis of enthalpy-entropy compensation is performed, and the compensation effect is shown to be true. It is found that the points corresponding to the investigated adsorbates are distributed over the compensation dependence according to the spatial structural characteristics of molecules.

  17. Growth and characteristics of InAsSb epilayers with a cutoff wavelength of 4.8 μm prepared by one-step liquid phase epitaxy

    Institute of Scientific and Technical Information of China (English)

    GAO Yuzhu; GONG Xiuying; FANG Weizheng; Akiniro Ishida

    2009-01-01

    InAsSb epilayers with a cutoff wavelength of 4.8 μm have been successfully grown on InAs substrates by one-step liquid phase epitaxy (LPE) technology. The epilayers were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) transmittance measurements and scanning electron microscopy (SEM). The influence of different growth conditions on the optical and structural properties of the materi-als was studied. The results revealed that the good crystalline quality, mirror smooth surface and flat interface of InAsSb epilayers were achieved. They benefited from optimized growth conditions, i.e., sufficient homogeneity of the growth melt and a very slow cooling rate.

  18. Research on the dynamic characteristics of gas-liquid two phase flow measurement with different throttle devices%不同节流装置测量气液两相流的动态特性研究

    Institute of Scientific and Technical Information of China (English)

    陈飞; 孙斌; 王二朋; 白宏震

    2012-01-01

    为了研究文丘里管、多孔孔板和V型内锥3种功能节流式流量计测量得到的气液两相流动态特性,采用高频差压传感器获取不同流型下的动态差压信号,利用AOK时频谱对差压信号进行分析,通过时频谱图研究不同流型下信号的时变特征.通过对典型的泡状流、弹状流、塞状流信号的实验分析表明:文丘里管在塞泡流存在较强的噪声信号,V型内锥在泡状流存在较强的噪声信号.多孔孔板具有很好的降噪效果,且多孔孔板能均衡信号的能量,信号能量分布较均衡.3种节流仪表均能很好地描述两相流定态特性,能够用于两相流流型识别及其它参数测量.%In this paper, the dynamic characteristics in the measurement of gas-liquid two-phase flow with different throttle flow-meters including Venturi tube, multi-hole orifices plate and V-shaped inner conical were studied. Firstly, high-frequency pressure sensor is adopted to get the dynamic differential pressure signal under different flow patterns. Secondly, the AOK spectrum is introduced and used in the analysis of the dynamic differential pressure signal. Then, the time-varying characteristic of dynamic differential pressure signal in different flow patterns is studied by estimating the time-frequency spectrum. It is indicated by experiments with the typical bubbly flow, slug flow and plug flow signals that Venturi tube has strong noise component at plug flow, and V-shaped inner cone has strong noise component at bubbly flow, multi-hole orifices plate is good at restraining noise. Furthermore, the multi-hole orifices plate can perform fine rectifying function and balance the energy of signals, which makes the energy distribution of signals more proportionate. The three kinds of throttling flow-meter can well describe the dynamic characteristics of gas-liquid two-phase flow, which can be used in the two-phase flow pattern I-dentification and characteristic variables

  19. Tribological Characteristics of Single-phase AlMgB14 and Nanocomposite AlMgB14-TiB2 Superhard Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun [ORNL; Blau, Peter Julian [ORNL; Zhu, Dong [Eaton Corporation; Cook, Bruce A [Ames Laboratory; Elmoursi, Alaa A [Eaton Corporation

    2008-01-01

    This study investigated the friction and wear characteristics of AlMgB14 and AlMgB14-TiB2 superhard coatings, produced by pulse laser deposition (PLD) and physical vapor deposition (PVD), respectively. Tests were conducted under unidirectional and reciprocating sliding against AISI 52100 bearing steel in both dry and oil-lubricated conditions. The AlMgB14 coating exhibited an encouraging but short-lived low friction stage (u = 0.2) in dry sliding. The AlMgB14-TiB2 coating reduced the wear rates by one order of magnitude for itself and three orders of magnitude for the counterface compared with the uncoated M2 tool steel in dry sliding. This nanocomposite coating also demonstrated significant extension (>2.5X) of the low friction (non-scuffing) stage in a lubricant starvation sliding.

  20. Energy storage and heat transfer characteristics of ground heat exchanger with phase change backfill materials%相变材料回填地埋管换热器蓄能传热特性

    Institute of Scientific and Technical Information of China (English)

    杨卫波; 孙露露; 吴晅

    2014-01-01

    points for the application of GSHP. In this paper, a new type of GHE with phase change backfill materials was presented to change its thermal response characteristics and heat transfer performance. Theoretically, the thermal interference radius of soil can be reduced by the phase change of phase change materials (PCM), and the energy storage performance of GHE can be improved due to the release of phase change latent heat. In order to further investigate the influences of solid-liquid phase change of phase change backfill materials on energy storage and heat transfer performance of GHE, a quasi-three dimensional heat transfer model with phase change was developed for the vertical U-bend GHE, which couples the one-dimensional fluid heat transfer in vertical direction with the two-dimensional soil transient heat transfer in level. The model was discreted by the control volume method and solved by the apparent heat capacity method. Based on the numerical solution of the model, the influences of solid-liquid phase change of PCM on energy storage performance of GHE and thermal response characteristics of soil temperature around GHE were analyzed for winter and summer mode respectively. The effects of phase change temperature and phase change latent heat of PCM on the thermal diffusivity and energy storage characteristics of GHE were discussed. The results indicate that under same conditions, the soil temperature variations trend is slow down and the thermal interference region is reduced due to the heat extraction and release during the phase change of PCM. The heat exchange performance of GHE can be evidently improved by backfilling materials with low and high phase change temperature for summer and winter respectively. At the same time, the energy storage performance can be enhanced by grouting the materials with large latent heat. The study is significant for releasing the thermal interference region of soil and improving the energy storage and heat transfer performance of

  1. Phases and Phase Transitions

    Science.gov (United States)

    Gitterman, Moshe

    2014-09-01

    In discussing phase transitions, the first thing that we have to do is to define a phase. This is a concept from thermodynamics and statistical mechanics, where a phase is defined as a homogeneous system. As a simple example, let us consider instant coffee. This consists of coffee powder dissolved in water, and after stirring it we have a homogeneous mixture, i.e., a single phase. If we add to a cup of coffee a spoonful of sugar and stir it well, we still have a single phase -- sweet coffee. However, if we add ten spoonfuls of sugar, then the contents of the cup will no longer be homogeneous, but rather a mixture of two homogeneous systems or phases, sweet liquid coffee on top and coffee-flavored wet sugar at the bottom...

  2. Influence of Tin Additions on the Phase-Transformation Characteristics of Mechanical Alloyed Cu-Al-Ni Shape-Memory Alloy

    Science.gov (United States)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Bakhsheshi-Rad, H. R.; Mohammed, M. N.

    2016-10-01

    The influence of the addition of Sn to Cu-Al-Ni alloy as a fourth element with different percentages of 0.5, 1.0, and 1.5 wt pct on the microstructure, phase-transformation temperatures, mechanical properties, and corrosion behaviors was investigated. The modified and unmodified alloys were fabricated by mechanical alloying followed by microwave sintering. The sintered and homogenized alloys of Cu-Al-Ni- xSn shape-memory alloys had a refined particle structure with an average particle size of 40 to 50 µm associated with an improvement in the mechanical properties and corrosion resistance. With the addition of Sn, the porosity density tends to decrease, which can also lead to improvements in the properties of the modified alloys. The minimum porosity percentage was observed in the Cu-Al-Ni-1.0 wt pct Sn alloy, which resulted in enhancing the ductility, strain recovery, and corrosion resistance. Further increasing the Sn addition to 1.5 wt pct, the strength of the alloy increased because the highest volume fraction of precipitates was formed. Regarding the corrosion behavior, addition of Sn up to 1 wt pct increased the corrosion resistance of the base SMA from 2.97 to 19.20 kΩ cm2 because of formation of a protective film that contains hydrated tin oxyhydroxide, aluminum dihydroxychloride, and copper chloride on the alloy. However, further addition of Sn reduced the corrosion resistance.

  3. Preparation and characteristics of high pH-resistant sol-gel alumina-based hybrid organic-inorganic coating for solid-phase microextraction of polar compounds.

    Science.gov (United States)

    Liu, Mingming; Liu, Ying; Zeng, Zhaorui; Peng, Tianyou

    2006-03-10

    A novel alumina-based hybrid organic-inorganic sol-gel coating was first developed for solid-phase microextraction (SPME) from a highly reactive alkoxide precursor, aluminum sec-butoxide, and a sol-gel-active organic polymer hydroxyl-terminated polydimethylsiloxane (OH-TSO). The underlying mechanism was discussed and confirmed by IR spectra. The porous surface structure of the sol-gel coating was revealed by scanning electron microscopy. A detailed investigation was conducted to evaluate the remarked performance of the newly developed sol-gel alumina-OH-TSO hybrid materials. In stark contrast to the sol-gel silica-based coating, the alumina-based coating demonstrated excellent pH stability. In addition, good thermal resistance and coating preparation reproducibility are also its outstanding performance. As compared to silica-based hybrids material, the ligand exchange ability of alumina makes it structurally superior extraction sorbents for polar compounds, such as fatty acids, phenols, alcohols, aldehydes and amines. Practical applicability of the prepared alumina-OH-TSO fiber was demonstrated through the analysis of volatile alcohols and fatty acids in beer. The recoveries obtained ranged from 85.7 to 104% and the relative standard deviation values for all analytes were below 9%.

  4. Improving the Quality of Urban Space and Shaping the Characteristics of Urban Culture: Under the Rapid Urbanization Phase of Jiangsu Province

    Institute of Scientific and Technical Information of China (English)

    Zhou; Lan; Yu; Chun; Zhang; Qingfei

    2015-01-01

    China is currently undergoing the most inf luential urbanization phase in its history, and this process will probably last for a few decades to come. Along with the accelerated urbanization, the quality of development has been elevated to an equal position with the quantity. Being one of the most developed and best urbanized provinces in China, Jiangsu has achieved an urbanization rate of 57%. Dealing with large construction scales, Jiangsu is presently striving to improve the quality of its urban space, and to elevate human settlements to a higher level. By contextualizing Jiangsu’s urbanization within a certain development stage and a specif ic historical era, the paper proposes the overall idea and action strategies for improving the quality of urban space, on the basis of the analysis on contemporary cultural pursuits. It aims at changing the current situation of "one outlook for thousands of cities," improving the quality of urban space and the competitiveness of urban culture, and eventually creating better human settlements and a harmonious society.

  5. Phase stability and superconducting characteristics of CaBa(La 1- xR x)Cu 3O 7- δ (R=rare earth) system

    Science.gov (United States)

    Gunasekaran, R. A.; Gopalakrishnan, I. K.; Sastry, P. V. P. S. S.; Yakhmi, J. V.; Iyer, R. M.

    1992-09-01

    It is concluded from detailed investigations on rare-earth-substituted 1113-system CaBaLa 1- xR xCu 3O 7- δ (R= Pr, Nd, Sm, Eu, Gd, Er, Ho, Dy, Yb and Tm) that only R=Pr and Nd have a complete range of solid solubility (0⩽ x⩽1.0). Among other rare-earth ions, only Sm( x⩽0.8) and Eu( x⩽0.6) have a large enough range of solid solubility, while the remaining undergo severe phase separation resulting in the formation of multiphase mixtures even for low values of x. The Tc-values of CaBaLa 1- xR xCu 3O 7- δ (R=Nd, Sm and Eu) show a decreasing trend with increase in x. In these respects, the influence of substitution of rare-earth ions in the CaBaLaCu 3O 7- δ system is quite different from that in YBa 2Cu 3O 7- δ, except that both CaBaPrCu 3O 7- δ and PrBa 2Cu 3O 7- δ are semiconducting.

  6. Study of some characteristic Mediterranean vegetation species best suited for renaturalization of terminal-phase municipal solid waste (MSW) landfills in Puglia (Southern Italy)

    Science.gov (United States)

    De Mei, Massimiliano; Di Mauro, Mariaida

    2006-07-01

    Natural recovery of worked-out or closed municipal solid waste (MSW) landfills is a current topic, but knowledge about the adaptability of Mediterranean vegetation species to such stressful conditions is still quite poor. Autochthonous plants were selected to withstand the stresses such as hot climate and drought typical of Mediterranean areas; this characteristic potentially allows the plants an easier, efficient adaptation. Our aim was to provide information in order to obtain an adequate quality of environmental renewal of a landfill and a reduced management cost while ensuring rehabilitation to an acceptable naturalistic state. The investigation lasted 3 years; some Mediterranean scrub native plant species were selected and monitored in their morphological (total and relative height, basal diameter, number of inter-nodes) and physiological (photosynthetic rate and water potential) activity. In order to test dependence on CO 2 concentration, different meteorological parameters were also monitored. Ceratonia siliqua, Phillyrea latifolia, Olea europaea and Quercus ilex showed considerable adaptability, reacting positively to every improvement in environmental conditions, particularly those of a meteorological nature. Survival and growth was satisfactory in Hedysarum coronarium, Medicago sativa, Lotus corniculatus, Rosmarinus officinalis, Myrtus communis and Viburnum tinus. Fraxinus ornus and Acer campestre suffered stress during the summer dry period and recovered quickly when atmospheric conditions improved. A drop irrigation system to ensure a satisfactory soil moisture during summer dry periods was the fundamental element for survival.

  7. Evaluation of the flow of cerebrospinal fluid as well as gender and age characteristics in patients with communicating hydrocephalus, using phase-contrast magnetic resonance imaging.

    Science.gov (United States)

    Bogomyakova, Olga; Stankevich, Yu; Mesropyan, N; Shaybman, L; Tulupov, A

    2016-12-01

    To determine the difference in the velocity parameters of cerebrospinal fluid flow in patients with varying severity of communicating hydrocephalus compared to a group of healthy volunteers without hydrodynamic disorders. The study involved 35 subjects with communicating hydrocephalus (25 subjects with Evans index of 0.31; 10 subject with Evans index of 0.46) and 62 healthy volunteers. The mean, volume, and peak flow velocities were determined at the different intracranial levels. Also were made an assessment of gender and age differences. Analysis of the differences between the mean values showed the progressive inhibition of cerebrospinal fluid outflow from the cranial cavity [in moderate communicating hydrocephalus-at 1.5 times (p hydrocephalus at 2-2.5 times (p < 0.01)], depending on the severity of enlargement of the ventricular system and, most likely, related to inhibition of its reabsorption. These changes may explain the clinical symptoms of subjects and serve as diagnostic criteria. Also it was revealed a significant influence of the factor of age on speed characteristics of the cerebrospinal fluid flow (F = 5.3303, p = 0.0003, for mean velocity).

  8. Ultrastructural characteristics of the spermatogenesis during the four phases of the annual reproductive cycle of the black myotis bat, Myotis nigricans (Chiroptera: Vespertilionidae).

    Science.gov (United States)

    Beguelini, Mateus R; Taboga, Sebastião R; Morielle-Versute, Eliana

    2013-10-01

    Myotis nigricans is an endemic species of vespertilionid bat, from the Neotropical region, that resembles temperate zone bats in their reproductive cycle; presenting an annual reproductive cycle with two periods of testicular regression, which are not linked to the apoptotic process and seems to be not directly linked to any seasonal abiotic variation. Thus, this study aimed to ultrastructurally evaluate their reproductive cycle. The process of testicular regression could be divided into four periods: active; regressing; regressed and recrudescence; with all presenting distinct characteristics. The active period was similar to that of other bats, presenting the complete occurrence of spermatogenesis, with three main types of spermatogonia (A(d), A(p), and B) and 12 steps in spermatid differentiation; however, it differed in having the outer dense fibers 1, 5, 6, and 9 larger than the others. These three types of spermatogonia undergo considerable morphologic changes from regressing to the regressed period, and in the recrudescence, they return to the basic morphology, which reactivates spermatogenesis. In conclusion, our study described the process of spermatogenesis, the ultrastructure of the spermatozoa and the distinct morphologic variations in the ultrastructure of the testicular cells of M. nigricans during the four different periods of its annual reproductive cycle.

  9. A study on the effect of gas flow rate on the wave characteristics in two-phase gas-liquid annular flow

    Energy Technology Data Exchange (ETDEWEB)

    Han Huawei [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, Ont., L1H 7K4 (Canada)]. E-mail: colin.han@uoit.ca; Zhu Zhenfeng [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Sask., S7N 5A9 (Canada)]. E-mail: zhz752@mail.usask.ca; Gabriel, Kamiel [University of Ontario Institute of Technology, Oshawa, Ont., L1H 7K4 (Canada)]. E-mail: kamiel.gabriel@uoit.ca

    2006-12-15

    Interfacial waves play a very important role in the mass, momentum and energy transport phenomena in annular flow. In this paper, film thickness time-trace measurements for air-water annular flow were collected in a small vertical tube using a parallel wire probe. Using the data, a typical disturbance wave shape was obtained and wave properties (e.g., width, height, speed and roughness) were presented. The liquid mass flux ranged from 100 to 200 kg/m{sup 2} s and the gas mass flux ranged from 18 to 47 kg/m{sup 2} s. Disturbance wave characteristics were defined and the effects of changing the gas flow rate on the wave spacing, wave width, wave peak height and wave base height were studied. An average velocity model for the wave and base regions has been developed to determine the wave velocity. The investigation method could be further extended to annular-mist flow which frequently occurs in boiling water reactors.

  10. Effect of different levels of crude protein and electrolyte balance on performance, blood parameters and bone characteristics for broiler chickens in phase of 36 to 42 days old

    Directory of Open Access Journals (Sweden)

    Franciele Clenice Navarini Giacobbo

    2014-09-01

    Full Text Available The aim of this study was to evaluate the effect of different levels of crude protein (CP and electrolyte balance (EB of the feed of broilers. 480 male broiler of Cobb 500 strain were fed in the period 36 to 42 days of age with two basal diets, one with EB 200 and another with 240 mEq. kg-1, combined with CP levels of 18.00, 17.28, 16.56 and 15.84%. The reduction in CP levels had growing linear effect (P <0.01 on feed conversion of birds (BE 200 and 240 even with the supplementation of industrial amino acids. For weight gain, reduced levels of CP had decreasing linear effect (P <0.01 to birds consuming diets with EB of 240 mEq. kg-1 and quadratic effect (P <0.05 for those who consumed ration with EB than 200 mEq. kg-1 being the level of 17.54%, which resulted in better weight gain of birds. There was linear effect (P <0.05 of reduction in CP levels on the plasmatic values of sodium (EB200 and chlorine (EB240 and quadratic effect (P <0.05 on plasmatic concentration of potassium (EB200 of birds, being the level of 17.05%, which provided the lower potassium values. For the plasma levels of uric acid, total protein and calcium, and bone development, reduction in the levels of CP had no effect on neither one of EB levels studied. Supplementation with bicarbonate salts of sodium and potassium chloride was not effective in improving the performance characteristics the birds, in the values of electrolyte balance studied, since there were no performance improvements with increase the electrolytic balance of the diets of 200 to 240 mEq.kg-1.

  11. Load frequency stabilization by coordinated control of Thyristor Controlled Phase Shifters and superconducting magnetic energy storage for three types of interconnected two-area power systems

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Praghnesh [Department of Electrical Engineering, Charotar Institute of Technology, Changa 388 421, Gujarat (India); Ghoshal, S.P. [Department of Electrical Engineering, National Institute of Technology, Durgapur 713 209, West Bengal (India); Roy, Ranjit [Department of Electrical Engineering, S.V. National Institute of Technology, Surat 395 007, Gujarat (India)

    2010-12-15

    In this paper, automatic generation control with interconnected two-area multi-unit all-hydro power system and two more test systems as all-thermal and thermal-hydro mixed haves been investigated. The transfer function of hydro turbine having non-minimum phase characteristics makes it different from the steam turbine. Upon application of small load perturbation to such all-hydro system, the frequency is severely disturbed and the system eventually becomes unstable. To stabilize the system for such load disturbance, comparative transient performance of two cases as (a) Thyristor Controlled Phase Shifter (TCPS) installed in series with the tie-line in coordination with Superconducting Magnetic Energy Storage (SMES) and (b) SMES located at each terminal of both areas are analyzed. It is observed that the case (b) i.e. SMES located at each terminal of both areas suppresses the frequency oscillations more effectively in integral controller assisted AGC of two-area multi-unit all-hydro system and the other two systems as well. In addition, the effectiveness of proposed frequency stabilizers is guaranteed by analyzing the transient responses of the system with different system parameters, various load patterns and in the event of temporary and permanent tie-line outage. Gains of the integral controller in AGC loop and parameters of TCPS and SMES are optimized with the help of a relatively novel particle swarm optimization, developed by the authors, called as craziness-based particle swarm optimization (CRPSO). The optimizing performance has been compared to that of real-coded genetic algorithm (RGA) to establish its superiority. (author)

  12. An Analysis of the Characteristics of Sports Teaching Objectives in Different Learning Phases%不同学段体育教学目标的特点分析

    Institute of Scientific and Technical Information of China (English)

    甘茂文

    2014-01-01

    从我国学校体育的目标出发,针对不同学段学生的成长特点,根据体育教学的规律性,在体育教学中适时、适量有侧重的选择合理的方法,科学地促进学生的身心发展。%Sports teaching is supposed to choose reasonable methods at the right time in moderate amounts with particular emphases, and scientifically promote the students' physical and mental development based on Chinese school sports goals, the characteristics of the students at different learning phases and the rules of sports teaching.

  13. Influence of built-up edge phases on characteristics of surface profile of micro cutting%积屑瘤状态对微细切削表面轮廓特征的影响

    Institute of Scientific and Technical Information of China (English)

    刘志兵; 王西彬

    2011-01-01

    研究了微细切削条件下,刀具前刀面上的积屑瘤状态对切削表面轮廓特征的影响,为合理选择和控制微细切削刀具的切削条件,以及评价微细切削的表面形貌特征提供实验依据.利用表面粗糙度仪分别提取了无积屑瘤、积屑瘤生长、稳定和脱落等4种积屑瘤状态下的切削表面轮廓,选取幅值密度函数(ADF)、自相关函数(ACF)和功率谱密度函数(PSD)等数理统计函数,以及时间序列模型参数和自回归(AR)谱分析了聚晶金刚石(PCD)刀具表面积屑瘤状态对微细切削表面轮廓特征的影响规律.结果表明,无积屑瘤和积屑瘤稳定阶段,AR谱的谱峰分别出现在91.7 c/mm和93.7 c/mm处,与进给量的倒数比较接近;积屑瘤生长和脱落状态阶段,谱峰出现的空间频率明显偏低,与进给量之间的对应关系不再显著.积屑瘤与切屑之间的不规则接触将破坏微细切削表面轮廓空间结构的一致性;积屑瘤生长和脱落阶段获得的表面轮廓的AR谱中存在明显的空间低频谱峰.%The influences of Built-up Edge(BUE) phases of a rake face on the characteristics of surface profile of micro cutting were researched, which provided the proof for the optimal selection of cutting parameters and the evaluation for the characteristics of surface profile of micro cutting. The surface profile data in micro cutting were measured with a profilometer in different BUE phases, BUE free,BUE formation, BUE stable and BUE drop. The influences of the BUEs on the characteristics of machined surface profiles were analyzed with mathematical statistical functions such as Amplitude Density Function(ADF), Auto-correlation Function(ACF) and Power Spectral Density Function(PSD), as well as the time series model parameters and Auto Regression(AR) spectra. Obtained results indicate that in BUE free and BUE stable phases, the AR spectral peaks of micro cutting surface locate at 91.7 c/mm and 93.7 c/mm, respectively

  14. Assessment of possible sources of microbiological contamination and water-quality characteristics of the Jacks Fork, Ozark National Scenic Riverways, Missouri; phase II

    Science.gov (United States)

    Davis, Jerri V.; Richards, Joseph M.

    2002-01-01

    August 6 to12, 2000. A 24-hour sample collection effort was conducted the weekend of July 15 and 16, 2000, to investigate the effect that large numbers of swimmers, canoeists, and tubers had on fecal coliform densities in the Jacks Fork. Five or six samples were collected at six sites between Saturday morning and the following Sunday afternoon. No fecal coliform density at any of the sites sampled exceeded the whole-body-contact recreation standard. Because bacteria survive longer in stream-bed sediments than in water, a source of bacteria in the water column could be from resuspension of accumulated bacteria from streambed sediments. Water and streambed-sediment samples were collected at three sites on August 3, 2000, 1 week before a trail ride and again at three sites on 2 Assessment of Possible Sources of Microbiological Contamination of the Jacks Fork, Missouri?Phase II August 8, 2000, during a trail ride. Results indicate that fecal coliform bacteria densities increased substantially in the streambed sediment and the water column during the trail ride.Sixty-five Escherichia coli isolates obtained from water samples collected at 9 sites and 23 Escherichia coli isolates obtained from stream-bed-sediment samples collected at 5 sites were submitted for ribotyping analysis. Samples were collected in 2000 during a variety of nonrecreational and recreational season river uses, including trail rides, canoeing, tubing, and swimming. Of the 65 isolates from water samples, 40 percent were identified as originating from sewage, 29 percent from horse, 11 percent from cow, and 20 percent from an unknown source. Of the 23 isolates from streambed-sediment samples, 39 percent were identified as originating from sewage, 35 percent from horse, 13 percent from cow, and 13 percent from unknown sources.Analysis of physical property (dissolved oxygen, pH, specific conductance, and temperature) and nutrient (dissolved nitrite plus nitrate and total phosphorus) data

  15. 厌氧折流板反应器处理PTA废水及其相分离特性%Terephthalic acid(PTA) wastewater treated by anaerobic baffled reactor and its phase separation characteristics

    Institute of Scientific and Technical Information of China (English)

    杨忠林; 钟中; 韩萍芳; 吕效平

    2012-01-01

    The start-up and phase separation characteristics of the anaerobic baffled reactor (ABR) treating purified terephthalic acid (PTA) wastewater were investigated. Results showed that under these conditions the temperature was (35 ± 1) ℃ , hydraulic retention time was 40 h and volumetric loading rate was 3.60 kg/(m3·d) , the ABR started up successfully and the maximum removal efficiency of COD reached 80% after 62 d operation. The concentration of volatile fatty acids ( VFA) in the different compartments of ABR decreased along the flow direction, In contrast, the content of CH4 , the volatile suspended solid (VSS) , the ratio of VSS and the total suspended solid (TSS) , the specific methane production activities and the coenzyme F420 increased, the significant phase separation characteristics.%对厌氧折流板反应器(ABR)处理精对苯二甲酸(PTA)生产废水的启动及相分离过程进行研究.结果表明:经过62 d的运行,反应器在(35±1)℃、水力停留时间40 h、容积负荷3.60 kg/(m3·d)的条件下,最大COD去除率达到80%以上,ABR启动成功.沿着水流方向,不同格室中挥发性脂肪酸(VFA)浓度依次减小,CH4含量不断增加,且污泥中挥发性悬浮固体浓度(VSS)及其与总悬浮固体浓度(TSS)之比、产甲烷活性和辅酶F420不断增大,ABR中显示出显著的厌氧微生物相分离特性.

  16. Characteristics of the entrained droplets in gas-liquid two-phase annular flow%气液两相环状流中夹带液滴特性研究

    Institute of Scientific and Technical Information of China (English)

    樊文娟; 彭颖

    2016-01-01

    气液两相环状流中液体薄膜沿着管壁流动而速度较大的气核在管中心流动,通常速度较大的气核会夹带部分液滴。液滴夹带来源于沿着管壁流动的液体层的雾化速率和液滴沉积速率之间的平衡过程。目前大多数环状两相流的研究主要集中在对主要夹带现象的分析上。文中主要从夹带液滴直径、液滴速度分布和夹带分数3个方面进行夹带液滴特性研究。%The liquid film flows along the pipe wall and the gas nucleus of higher speed flows in the center of the pipe flow in the gas-liquid two-phase annular flow,usually the high speed gas nucleus entrains some droplets. The droplet entrainment is derived from a balance between the rate of atomization of the liquid layer flowing along the pipe wall and the rate of deposition of droplets. When gas flow rate is low,gravity sedimentation controls the deposition rate,and when the gas phase is at high flow velocity,droplet turbulence controls the deposition rate. At present,most of the annular two-phase flow research focuses on the analysis of the main entrainment phenomenon. This article mainly discussed the entrained droplets from the gas liquid interface,because the entrained droplets play an important role in a lot of flow parameters. Therefore, this article made the droplet entrainment characteristics research mainly from the three aspects,namely droplet diameter, droplet velocity distribution and entrainment fraction.

  17. Research progress of particle rotation characteristics in multi-phase flows%多相流中颗粒旋转运动特性的研究进展

    Institute of Scientific and Technical Information of China (English)

    王勤辉; 杨秋辉; 吴学成; 骆仲泱; 岑可法

    2011-01-01

    Investigation of dispersed particle rotation characteristics in multi-phase flow is important in understanding the mechanism of multi-phase flow. In previous studies, many people focused on Magnus force produced by particle rotation in solid-gas two-phase flow, and proposed Magnus lift coefficient at different Reynolds numbers through experimental and theoretical investigations. In recent years, many researchers have studied the effect of particle rotation on the flow field through theoretical numerical simulation and dealt with particle rotation by improving multi-phase flow numerical model, and the simulated results are in agreement with experimental results. But because of the limitation of the model, it is impossible to take into full account the influence of particle rotation on particle cluster and surrounding flow field. From the experimental aspect, many researchers use high-speed digital imaging system to measure particle rotation speed and particularly one author successfully measured particle rotation speed in real gas-solid two-phase flow. Nevertheless, more accurate and efficient method needs to be developed. The authors of this paper proposed that the application of the direct numerical simulation in particle rotation characteristics simulation should be the emphasis of research in the future. And the technology of the reconstruction of 3D motion and structure of the object from image sequence in computer vision science should also be paid much attention in particle rotation speed measurement.%多相流中分散相颗粒旋转运动特性研究对于进一步揭示多相流机理有重要意义,同时也有助于人们更全面地认识多相流动,因此,越来越受到学者们的关注.近年来,人们从理论模拟方面研究颗粒旋转对流场的影响,通过改进多相流数值模型来考虑颗粒旋转,获得了与实验吻合的结果,但由于模型本身的局限性,无法全面考虑颗粒旋转运动对颗粒群和周围流场的影

  18. 摇摆工况下窄矩形通道内两相沸腾摩擦压降特性%Two-phase frictional pressure drop characteristics of boiling flow in rectangular narrow channel under rolling motion

    Institute of Scientific and Technical Information of China (English)

    陈冲; 高璞珍; 余志庭; 陈先兵

    2015-01-01

    In order to investigate the two-phase frictional pressure drop characteristics of boiling flows in a rectangular narrow channel under rolling motion, a series of thermal hydraulic experiments and theoretical analysis are performed. The results demonstrate that the additional inertial force is imposed on the fluid and the space of experimental loop will vary periodically under rolling motion. The fluctuation amplitude of the two-phase frictional gradient increases with increasing rolling angle and rolling period. The fluctuation amplitude and time average value of the two-phase frictional pressure gradient increase with increasing heat flux, while it decreases with the increase of system pressure. The mass flux varies with the fluctuation of frictional pressure gradient at the same period. The phase change between the fluctuation of mass flux and frictional pressure gradient is approximately equal to 1/4 rolling period due to the velocity difference of the pressure propagation and mass flux increases.%为了研究摇摆工况下窄矩形通道内的两相摩擦压降特性,进行了一系列的热工水力实验和理论分析。结果表明,摇摆工况下流体会受到附加惯性力的作用且实验回路的空间位置也会出现周期性的变化,两相摩擦压降梯度的波动振幅随着摇摆角度和摇摆周期的增加而增加;随着通道热通量的增加或者系统压强的减小,两相摩擦压降梯度的波动振幅和时均值逐渐增加。窄矩形通道内的质量流速随着两相摩擦压降梯度的波动而波动,且具有相同的波动周期,由于流体加速和压力传播的速度不同,流量波动和摩擦压降波动存在约1/4周期的相位差。

  19. Spatiotemporal Characteristics of Visual Localization. Phase 2.

    Science.gov (United States)

    1987-09-30

    low end for 4 ., t. , h -tr% er F ig i . h o t n t fo r th e o th e r [F ig . 5 (B )),_ _s_ _ _ _ _ _ _ _ _, _ _ _ , h,, i -. t e -v, od h-, erer ...the re,jlts obtained at dratn. with ihrupt inset. tni ?.rnutnt, .I ( "l-,*r’ r -iill lie(t eparatliin,, but it sig tuiiantlv reduced the ibt, A, erer

  20. 融合局部gabor相位特征和全局本征脸的人脸识别算法%Face Recognition Based on Fusion of Local Gabor Phase Characteristic and Global Intrinsicfaces

    Institute of Scientific and Technical Information of China (English)

    江艳霞; 王娟; 唐彩虹

    2012-01-01

    A new face recognition method, which is based on fusion of local gabor phase characteristic and global intrinsicfaces is developed in this paper. There are three steps in our proposed method. Firstly, According to the good spatial position and orientation of gabor filter, a gabor filter is applied to filter face images. Local gabor phase characteristics are extracted and fisher linear discriminant analysis is used to project these charactersitics of each spatial position and orientation into low dimensional space. Local classifying scores are developed by fusion of scores in all the spatial and orientations. Secondly, Intrinsic Discriminant Analysis (IDA) which tries to best classify different face images by maximizing the individuality difference, while minimizing the intrapersonal difference is applied to get the global classifying scores. Finally, the local scores and global scores are fused to get the classifying result. Experimental results on three dataset show that our method can have good recognition performance.%提出一种融合局部gabor相位特征和全局本征脸特征进行人脸识别的方法.该方法采用多个分类器的集成,首先利用gabor滤波良好的空间位置与方向选择特性,用gabor滤波器对图像进行滤波,采用局部XOR算子提取滤波图像的局部gabor相位特征,通过Fisher判别式对每个频率和方向下的相位特征进行降维,融合各个频率和方向下的分类概率,得出局部特征分类信息;然后利用本征判别式方法,得出人脸图像的全局分类信息;最后融合局部和全局分类信息进行识别.通过在三个人脸库中的实验结果显示,本文提出的方法具有很好的识别性能.

  1. PEG/PVA相变复合纳米纤维的制备及其性能研究%Prepare PVA/PEG phase change composite nanofibers and study its characteristics

    Institute of Scientific and Technical Information of China (English)

    张梅; 刘永佳; 栾加双; 徐天宇; 孙大辉

    2012-01-01

    在室温下制得了PEG/PVA相变复合纳米纤维。探讨了PVA/PEG和PEG2000/PEG4000各自不同质量分数、外加电压、接收距离、外加盐离子等参数对纤维直径和纤维网形态的影响。结果表明PEG/PVA为60/40,电压为15kV,接受距离为10cm时,成纤较好。运用DSC测试复合纳米纤维的可逆相转变特性,Tm和TC值与PEG2000/PEG4000的比例有关。%In this work,PVA /PEG phase change composite nanofibers were prepared by electrospinning at room temperature.The diameter and morphology of PVA / PEG nanofibers were studied by scanning electron microscopy(SEM) to research the relationship with different weight content,applied voltage,collect distance and added ionic salt on fiber diameter and fiber network morphology.Experimental results showed that PVA/PEG blend solution of 4∶6 weight content,a fixed electric field of 15kV/10cm was the best process parameters.Using DSC method,the phase change characteristics of PVA/PEG composite nanofibers has been tested.Tm and TC values are affected by different ratios of PEG component(Mw = 2000,4000).

  2. Synthesis, structural characteristics and dielectric properties of a new K{sub 2}NiF{sub 4}-type phase Sr{sub 2}Mn{sub 0.5}Ti{sub 0.5}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Chupakhina, T.I., E-mail: chupakhina@ihim.uran.ru [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, 91, Pervomaiskaya Str., Ekaterinburg (Russian Federation); Melnikova, N.V. [Ural Federal University, 19, Mira Str., Ekaterinburg (Russian Federation); Gyrdasova, O.I. [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, 91, Pervomaiskaya Str., Ekaterinburg (Russian Federation)

    2016-06-15

    A new K{sub 2}NiF{sub 4}-type phase Sr{sub 2}Mn{sub 0,5}Ti{sub 0,5}O{sub 4} have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermogravimetric analysis and scanning electron microscopy. There are no oxide ion vacancies in these materials; oxidation states of manganese and titanium were estimated as +4. Rietveld profile analysis shows that the phase crystallizes with tetragonal unit cell in the space group I4/mmm. Substitution of Ti{sup 4+} for Mn{sup 4+} does not affect the distortion of coordination polyhedra (Mn,Ti)O{sub 6} and SrO{sub 9}. The dielectric properties of the ceramic samples are caused by structural and charge characteristics, regular coordination polyhedra SrO{sub 9} and lack of charge ordering, which can lead to significant permittivity. Increase of the dielectric constant at temperatures above 453 K is caused mainly by the grain boundary processes explained in terms of the Maxwell–Wagner polarization model. - Highlights: • The new complex oxide Sr{sub 2}Mn{sub 0,5}Ti{sub 0,5}O{sub 4} was prepared. • The structures of the compound were analyzed by Rietveld refinement. • Distortions of SrO{sub 9} and (Mn,Ti)O{sub 6} polyhedra are not strong. • Dielectric properties are determined by regular structure and lack of charge ordering. • Permittivity increase under heat is associated with processes at the grain boundaries.

  3. Transient characteristic research of doubly-fed induction generator during single-phase grounding fault%双馈异步发电机单相接地故障瞬态特性研究

    Institute of Scientific and Technical Information of China (English)

    沈浩然; 张建华; 丁磊; 戴春蕾

    2015-01-01

    为了便于研究 DFIG 在不对称电压跌落下低电压穿越运行的控制策略,有必要对不对称电压跌落时 DFIG的瞬态特性进行研究.基于DFIG定、转子磁链的瞬态变化机理,对DFIG单相接地故障瞬态特性进行研究,推导出了DFIG在发生单相接地故障时的定、转子电流,电磁转矩,输出有功功率与无功功率的解析表达式,并分析得到影响单相接地故障时电磁过渡过程的主要因素.在Matlab/Simulink中搭建了1.5 MW双馈异步发电机单相接地故障仿真模型.仿真结果和解析计算结果高度吻合,证明了推导的解析表达式的正确性和有效性,为双馈异步发电机不对称LVRT控制策略提供了理论基础.%In order to research the control strategy of low voltage ride through (LVRT) of DFIG during the asymmetric voltage sag, it is necessary to research the transient characteristic of DFIG during the asymmetric voltage sag. This paper utilizes the transient change mechanism of DFIG stator and rotor flux in the case of single-phase grounding fault, deduces and obtains analytical expressions about stator transient current, electromagnetic torque, output active power and reactive power of DFIG. On the basis of above, the main factors are got which affect single-phase grounding fault electromagnetic transient process. And simulation model of 1.5 MW DFIG during single-phase grounding fault is built on MATLAB/Simulink, the simulation results are closely consistent with the analytical calculation results, which shows the correctness and effectiveness of the analytical expressions derived. Analysis of this paper can provide theoretical basis for control strategy of asymmetric LVRT.

  4. Differential Phase Detector for Precise Phase Alignment

    CERN Document Server

    Olexa, Jakub

    2016-01-01

    This paper presents a differential phase detector circuit, whose phase-to-voltage characteristic has an extremum when its two input signals are exactly in phase. In this condition all its digital signals are of 50 % duty cycle so that the circuit characteristic does not have a dead zone. This feature allows a precise indication of the zero-phase condition, which is independent of the detector power supply and the offset of its ADC readout. Such a detector is used for a phase alignment of two reference clock signals with frequency about 11 kHz in front-ends processing signals from beam position monitors of the Large Hadron Collider (LHC) at CERN. The detector output voltage is digitized with a 24-bit ADC at the rate of the reference signals. The resulting samples are processed in the front-end FPGA and transmitted to the control system using an Ethernet data stream. After a detailed description of the differential phase detector its performance is demonstrated with laboratory measurements. The results show tha...

  5. Phase transition of rheologic characteristics in non-viscous grain suspension and its percolation model%非粘性颗粒悬浮液流变特性的相变及其渗流模型

    Institute of Scientific and Technical Information of China (English)

    罗文锋; 艾南山; 李后强; 丁晶

    2001-01-01

    It is supposed that there is a second order phase transition in the changing process of rheologic characteristic for varying volume concentration in non-viscous grain suspension. A directed cubic sitepercolation model is introduced as the simplified physical picture of the forming mechanism of Bingham yield stress in suspension. Theoretically analytical concentration is 0.173, and it could be inlerpret as the theoretical lower limit of transition volume concentration.%本文提出非粘性颗粒悬浮液流变性质随颗粒体积浓度的变化过程中存在一个二阶相变.在假设颗粒为均匀圆球,且颗粒排列方式为简立方结构的简化条件下,利用三维简立方定向座渗流模型作为描述悬浮液宾汉极限剪切力产生的物理机制的简化物理图像,得到悬浮液流变性质相变体积浓度的理论值为0.173,这个值可以作为相变体积浓度的理论下限值.

  6. Single-Phase PLLs

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different...... structures and properties have been proposed in the literature. The main aim of this paper is to provide a review of these PLLs. To this end, the single-phase PLLs are first classified into two major categories: 1) power-based PLLs (pPLLs), and 2) quadrature signal generation-based PLLs (QSG-PLLs......). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....

  7. 基于RC网络相频特性的土壤含水率传感器设计%Design of soil moisture sensor based on phase-frequency characteristics of RC networks

    Institute of Scientific and Technical Information of China (English)

    蔡坤; 岳学军; 洪添胜; 徐兴; 黄双萍

    2013-01-01

    Dielectric-based methods are widely used due to their non-destruction, efficiency and accuracy. The capacitance of the probe on the sensor is affected by the soil moisture. Therefore the mathematical model can be built between the capacitance of the sensor and the soil moisture. In this paper, a new soil water content sensor based on the phase-frequency characteristic of RC network is proposed. The sensor consists of four parts, that is a VHF oscillator, a phase-detecting circuit, a first-order RC low-pass circuit, and a probe. The VHF oscillator outputs a frequency-specified f* signal to drive the RC network, and the capacitor C of the first-order RC low-pass network is replaced by the capacitance of the probe of the sensor. Moreover, the changes of capacitance of the probe brought by the change of the soil moisture will cause a significant change in the phase-frequency response of the RC network. The AD8302 phase-detector is used to measure the change of the phase-frequency response of the RC network by converting the phase angle of the RC network to a voltage signal. Thus, the relationship between the soil moisture content and the output voltage signal can be built to estimate water content in soil. Compared with existing published works on the theoretical implementation which has low accuracy and sensitivity of the sensor, the proposed sensor is optimized by the following steps:1) The measurement equivalent circuit model of the first-order RC low-pass circuit along with the input equivalent circuit of AD8302 is built;2) The relationship between the output voltage signal of AD8302 with the phase-frequency response of the measurement equivalent circuit with a specified frequency f and the resistor R of RC network is derived; 3) Formulating the optimization problem by maximizing the integration of change of the output voltage of AD8302 in the entire predefined variation range of the capacitor C of the RC circuit, 1×10-12 F

  8. Moon Phases

    Science.gov (United States)

    Riddle, Bob

    2010-01-01

    When teaching Moon phases, the focus seems to be on the sequence of Moon phases and, in some grade levels, how Moon phases occur. Either focus can sometimes be a challenge, especially without the use of models and observations of the Moon. In this month's column, the author describes some of the lessons that he uses to teach the phases of the Moon…

  9. Experimental Research on Operating Frequency Effect on the Characteristics of Two?Phase Detonation Initiation%频率对两相爆震波起爆特性影响的实验研究

    Institute of Scientific and Technical Information of China (English)

    王治武; 张洋; 陈星谷; 郑龙席; 卢杰

    2015-01-01

    为了掌握爆震频率对两相多循环爆震波起爆特性的影响规律,对采用高能火花塞点火的吸气式脉冲爆震发动机不同爆震频率下的起爆过程进行了试验研究,对比分析了不同频率下的P DE沿程压力分布,讨论了起爆特征参数,如DDT转变距离、着火延迟时间、DDT转变时间和起爆时间等,与爆震频率的变化关系. 试验结果显示,随着工作频率增加,爆燃燃烧向爆震燃烧的转变有所加快. 工作频率对着火延迟时间和爆震形成时间影响较大,对DDT时间影响很小,随着频率增加,着火延迟时间和爆震形成时间逐渐减小,而DDT时间略有下降.%In order to grasp the influence of detonation frequency on the initiation characteristics of two?phase multi?cycle detonation, an air?breathing pulse detonation engine mockup with high energy spark plug was designed and the experiments of detonation initiation process at different operating frequencies were carried out. The pressure dis?tributions along the length of PDE mockup at different operating frequencies were contrasted and analyzed. Mean?while , the relationship between the detonation frequency on the one hand and the initiation characteristic parameters on the other hand was discussed, such as the DDT transition distance, ignition delay time, DDT transition time and detonation initiation time and so on. The experimental results indicated that deflagration to detonation transition in?creased with increasing operating frequency. The operating frequency had obvious effect on ignition delay time and the detonation initiation time but had a weak effect on DDT time. As the operating frequency increased, the ignition delay time and detonation initiation time decreased linearly, while the DDT time declined slightly.

  10. Effect of rate of weight gain of steers during the stocker phase. IV. Rumen fermentation characteristics and expression of genes involved in substrate utilization for fatty acid synthesis in adipose tissues of growing-finishing beef cattle.

    Science.gov (United States)

    Lancaster, P A; Sharman, E D; Horn, G W; Krehbiel, C R; Dillwith, J W; Starkey, J D

    2015-06-01

    The objective of this study was to determine the impact of stocker production systems differing in growth rate on rumen fermentation characteristics and utilization of substrates for fatty acid synthesis in intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissues. Angus steers were assigned to 4 stocker cattle production systems in 2 consecutive years: 1) 1.0 kg/d of 40% CP cottonseed meal–based supplement while grazing dormant native range (CON), 2) ground corn/soybean meal–based supplement while grazing dormant native range fed at 1% of BW (CORN), 3) grazing wheat pasture at a high stocking rate to achieve a low rate of BW gain (LGWP), and 4) grazing wheat pasture at a low stocking rate for a high rate of BW gain (HGWP). Eight ruminally cannulated steers were used to determine rumen fermentation characteristics. Steers were harvested during the stocker phase at similar age (different carcass weight) in Exp. 1 (3 steers/treatment) or at similar carcass weight in Exp. 2 (4 steers/treatment). Adipose tissues were analyzed for mRNA expression of genes involved in glucose (solute carrier family 2, member 4 [GLUT4], glucose-6-phosphate dehydrogenase [G6PDH], phosphofructokinase, muscle [PFKM], and pyruvate kinase 2, muscle [PK2]), lactate (lactate dehydrogenase B [LDHB]), and acetate (acetyl-CoA synthetase, cytosol [ACSS2]) utilization for fatty acid synthesis. The acetate:propionate ratio was least (P adipose tissue. Expression of PFKM and PK2 mRNA tended (F-test; P adipose tissue. At similar HCW, expression of GLUT4 and G6PDH mRNA were greater (P adipose tissue of LGWP and HGWP steers compared with CON and CORN steers but not in IM and PR adipose tissue. Expression of LDHB mRNA was lesser (P adipose tissue but greater (P adipose tissue of LGWP and HGWP steers compared with CON and CORN steers. These results indicate a shift toward glucose utilization in SC adipose tissue but a shift towards lactate utilization in PR adipose tissue. These results

  11. Micro Scopic-characteristics of Sodium Sorbate in Solid-phase Reaction Processing%山梨酸钠固相反应生产过程中的微观特征

    Institute of Scientific and Technical Information of China (English)

    仝其根; 甘小花; 白云起

    2011-01-01

    采用山梨酸和碳酸钠固相反应生产山梨酸钠过程中,会出现反应体系温度突然升高,反应物粘接,反应不易进行彻底,碱的加入量超过化学反应比例等问题,从而影响反应的进行和产品质量.为解决这些问题,利用X-射线衍射、扫描电镜、差热及热重分析方法,对其固相反应过程的微观变化特征进行研究,结果表明:山梨酸与碳酸钠固相反应产生的热、水及研磨力是固相反应进行的内在动力,山梨酸晶体崩解是反应体系温度快速升高最重要的原因;中和反应生成的水会使物料之间产生粘接,在其后有一部分成为山梨酸钠的结晶水;碳酸钠在反应过程生成碳酸氢钠是影响碱超标、反应不易进行彻底等问题的最直接原因.%During the solid-phase reaction process of sodium sorbate and sodium carbonate to produce sodium sor-bate, here appeared that the temperature of reaction system jumped higher, reactants bounding which lead to the reaction uncontrollable and the addition of sodium carbonate more than chemical reaction needed. These results would affect practical reaction process and the quality of the resulting product. In our presented study, X-ray diffraction analysis, scanning electron microscopy analysis, differential thermal and thermogravimetry analysis were used to study solid reaction process of sodium sorbate and sodium carbonate, and its micro scopic variety characteristics. The results showed the heat, water produced during reaction and the milling and grinding force applied in solid-phase reaction of sodium sorbate and sodium carbonate trigged the occurrence of the reaction and considered to be the internal driving force of the reaction, while the collapsing of sorbic acid crystal was to be the most important factor for the rapid increase of reaction temperature in reaction system. The water produced in neatralizing reaction led to the reactants bounded during rection, and part of them

  12. 泉州市麻疹在“消除阶段”的流行病学特征分析%Analysis on epidemiological characteristics of measles at elimination phase

    Institute of Scientific and Technical Information of China (English)

    黄彩虹; 洪思让; 陈雅红

    2013-01-01

    目的 分析泉州市麻疹在“消除阶段”(2006-2011年)的流行病学特征,为调整麻疹防制对策,实现消除麻疹目标提供依据.方法 对麻疹发病监测资料和防制对策进行描述流行病学分析.结果 2006-2011年报告发病率最高的是晋江(6/10万),最低的是永春(0.16/10万).发病高峰后移或消平.病例主要以外地户籍人口为主,占56%.发病年龄有呈双向位移的趋势,<8月龄组和≥15岁组的人群所占比例增高.无麻疹疫苗免疫史的是发病的主体.发病前7~21 d去过医院的病例占57%.结论 通过消除麻疹免疫空白人群,强化麻疹疫情应急处理能力,控制医院感染等综合防控措施,是消除麻疹的关键.%Objective This study was to get a comprehensive understand of the epidemiological characteristics of measles in Quanzhou city at elimination phase (2006-2011), adjust the prevention countermeasures of measles and provide basis to reach the goal of eradication of measles. Method Descriptive epidemiological analysis of monitoring data and control measures on the incidence of measles. Results During 2006 to 2011 , the highest incidence rate of 6 per 100 000 was reported by Jinjiang, and the lowest incidence of 0.16/100 000 appeared in Yongchun. Incidence peak was shifted or eliminated. Cases are mainly non-household population, accounting for 56%. The age of onset was two-way trend of displacement. People with no measles vaccination were the main contribution to the incidence. The cases had been to the hospital 7~21 days before the onset of symptoms, accounted for 57%. Conclusion Increase in the vaccination rate of the population, improving the ability of emergency response to measles outbreaks and controlling hospital' infection are the keys to eliminate measles.

  13. Phase I of The National Beef Quality Audit-2011: quantifying willingness-to-pay, best-worst scaling, and current status of quality characteristics in different beef industry marketing sectors.

    Science.gov (United States)

    Igo, J L; VanOverbeke, D L; Woerner, D R; Tatum, J D; Pendell, D L; Vedral, L L; Mafi, G G; Moore, M C; McKeith, R O; Gray, G D; Griffin, D B; Hale, D S; Savell, J W; Belk, K E

    2013-04-01

    The National Beef Quality Audit (NBQA)-2011 benchmarked the current status of and assessed progress being made toward quality and consistency of U.S. cattle, carcasses, and beef products after the completion of the first NBQA in 1991. Unlike previous NBQA, objectives of the 2011 Phase I study were to determine how each beef market sector defined 7 quality categories, estimate willingness-to-pay (WTP) for the same quality categories by market sector, and establish a best-worst (B/W) scaling for the quality categories. Structured face-to-face interviews were conducted and responses were recorded using dynamic routing software over an 11-mo period (February to December 2011) with decision makers in each of the following beef market sectors: Feeders (n = 59), Packers (n = 26), Food Service, Distribution, and Further Processors (n = 48), Retailers (n = 30), and Government and Allied Industries (n = 47). All respondents participated in a structured interview consisting of WTP and B/W questions that were tied to 7 quality categories and then were asked to "define" each of the 7 categories in terms of what the category meant to them, resulting in completely unbiased results. The 7 quality categories were a) how and where the cattle were raised, b) lean, fat, and bone, c) weight and size, d) cattle genetics, e) visual characteristics, f) food safety, and g) eating satisfaction. Overall, "food safety" and "eating satisfaction" were the categories of greatest and second most importance, respectively, to all beef market sectors except for Feeders. Feeders ranked "how and where the cattle were raised" and "weight and size" as the most important and second most important, respectively. Overall, "how and where the cattle were raised" had the greatest odds of being considered a nonnegotiable requirement before the raw material for each sector would be considered for purchase and was statistically more important (P market sectors were considered, "eating satisfaction" was shown to

  14. 方柱体与圆柱体气液两相涡街特性的研究%Study of Gas-liquid Two-phase Vortex Street Characteristics of a Square Cylinder and a Circular One

    Institute of Scientific and Technical Information of China (English)

    周云龙; 刁成东; 曹茹

    2009-01-01

    When a gas-liquid two-phase fluid in a vertically ascending tube with a rectangular section transversely scours a horizontally arranged cylinder,under certain conditions,an alternating vortex shedding phenomenon will occur at the back of the cylinder.By adopting a tube-wall pressure-difference method to study the vortex shedding characteristics of the above flow transversely sweeping across a circular cylinder and a square one,the authors have identified the vortex street shedding frequency and the variation of Strouhal number.During the test,the Reynolds number ranges from 0.9×10~4 to 2.3×10~4 and the sectional gas content has a variation range of 0 to 0.2.The test results indicate that in a certain range of gas content,the vortex-street shedding frequency and Strouhal numbers of the two types of cylinders will increase with an increase of the sectional gas content.The increment gradient of the square cylinder Strouhal number is independent of the Reynolds number while that of the circular one is susceptible to the influence of the Reynolds number.%气液两相流体在垂直上升矩形截面管道内横向冲刷水平布置的柱体时,一定条件下会在柱体后面产生旋涡交替脱落现象.利用管壁压差法来研究气液两相流横掠圆柱体和方柱体时的旋涡脱落特性,得到了涡街的脱落频率和斯特罗哈数的变化情况.实验中雷诺数的范围为0.9×10~4~2.3×10~4,截面含气率的范围为0~0.2.实验结果表明:在一定的含气率范围内,两种柱体涡街的脱落频率与斯特罗哈数都随着截面含气率的增大而增大;方柱体斯特罗哈数增大的梯度与雷诺数无关,圆柱体斯特罗哈数增大的梯度受雷诺数的影响.

  15. Comparative analysis of electro-mechanical characteristic of a three-phase induction motor with 1,5 CV with high performance and conventional one; Analise comparativa das caracteristicas eletromecanicas entre um motor de inducao trifasico de 1,5CV de alto-rendimento e convencional

    Energy Technology Data Exchange (ETDEWEB)

    Mendieta, J.C.V. [Dalkia, Rio de Janeiro, RJ (Brazil); Bertoleti, P.H.F.; Magalhaes Sobrinho, P. [Universidade Estadual Paulista (LAMOTRIZ/UNESP), Guaratingueta, SP (Brazil). Lab. de Otimizacao de Sistemas Motrizes Industriais; Souza, T.M. [Universidade Estadual Paulista (UNESP), Guaratingueta, SP (Brazil)

    2009-07-01

    In Brazil, the electric power consumed by three-phase induction motors corresponding to approximately 55% of total electric power consumed by the industrial sector. Therefore, a thorough analysis of this type of engine under the questions of energy saving, economic viability and electro-mechanical characteristics are needed. This work deals with the comparative analysis for two motors three-phase induction, one conventional and another with high performance (manufacturer WEG and IP55 protection grade), aiming to obtain the necessary relationships to do an economical and electro-mechanical analysis.

  16. Learner Characteristics

    NARCIS (Netherlands)

    Drachsler, Hendrik; Kirschner, Paul A.

    2011-01-01

    Drachsler, H., & Kirschner, P. A. (2012). Learner Characteristics. In N. M. Seel (Ed.), Encyclopedia of the Sciences of Learning, Volume 4 (pp. 1743-1745). New York: Springer. DOI: 10.1007/978-1-4419-1428-6_347

  17. Multi-scale cross-correlation characteristics of void fraction wave propagation for gas-liquid two-phase flows in small diameter pip e%小管径气液两相流空隙率波传播的多尺度相关性∗

    Institute of Scientific and Technical Information of China (English)

    翟路生; 金宁德

    2016-01-01

    The void fraction wave is a special physical phenomenon in a gas-liquid two-phase flow system. Understanding the propagation of the void fraction wave is of great significance for uncovering the physical mechanisms in both flow pattern transition and the fluid velocity measurement. In this study, detrended cross-correlation analysis (DCCA) is used to investigate the multi-scale cross-correlation characteristics of the coupled ARFIMA processes. It is found that the DCCA can effectively reveal the multi-scale cross-correlation dynamical behaviors of complex system. Then, we carry out the experimental test in a vertical gas-liquid two-phase flow pipe with small inner diameter. The DCCA is used to detect the cross-correlation characteristics of the void fraction wave on multiple time scales, and the growth rate of the cross-correlation level for the void fraction wave is observed on low time scales. Additionally, the spatial attenuation factor (SAF) of the void fraction wave is calculated to investigate the instability of the wave propagation. The SAF is close to zero under the transitional flow patterns, which means that the void fraction wave is in a stable propagating state. For bubble flows, the void fraction wave presents the attenuation characteristics, whilst the void fraction wave shows the amplification characteristics under the slug and churn flow patterns. Interestingly, the instability behaviors of the void fraction wave are always associated with its multi-scale cross-correlation characteristics. Specifically, the increasing rate of the wave cross-correlation level on low scales is much higher for transitional flow patterns, which is corresponding to the stable propagating characteristic of the void fraction wave. However, when the void fraction wave exhibits attenuation or amplification characteristics under other flow patterns, the increasing rate of the wave cross-correlation level on low scales is much lower.

  18. Amplitude and phase noises of a spin-transfer nano-oscillator synchronized by a phase-lock loop

    Science.gov (United States)

    Mitrofanov, A. A.; Safin, A. R.; Udalov, N. N.

    2015-08-01

    We have studied the amplitude and phase noises of a spin-transfer nano-oscillator (STNO) with a phase synchronization system (phase-lock loop, PLL). Spectral characteristics of the amplitude and phase noises of the isochronous and nonisochronous STNO are obtained and compared to the analogous characteristics of an autonomous (nonsynchronized) oscillator. The PLL bandwidth is determined.

  19. Electron microscope phase enhancement

    Science.gov (United States)

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  20. Phase transitions

    CERN Document Server

    Solé, Ricard V

    2011-01-01

    Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation o

  1. Algorithm for Screening Phasor Measurement Unit Data for Power System Events and Categories and Common Characteristics for Events Seen in Phasor Measurement Unit Relative Phase-Angle Differences and Frequency Signals

    Energy Technology Data Exchange (ETDEWEB)

    Allen, A.; Santoso, S.; Muljadi, E.

    2013-08-01

    A network of multiple phasor measurement units (PMU) was created, set up, and maintained at the University of Texas at Austin to obtain actual power system measurements for power system analysis. Power system analysis in this report covers a variety of time ranges, such as short- term analysis for power system disturbances and their effects on power system behavior and long- term power system behavior using modal analysis. The first objective of this report is to screen the PMU data for events. The second objective of the report is to identify and describe common characteristics extracted from power system events as measured by PMUs. The numerical characteristics for each category and how these characteristics are used to create selection rules for the algorithm are also described. Trends in PMU data related to different levels and fluctuations in wind power output are also examined.

  2. Experimental study on the characteristic and mechanism of body fluid metabolism in acute reaction phase of severe acute pancreatitis%重症急性胰腺炎早期体液代谢特点及机制

    Institute of Scientific and Technical Information of China (English)

    徐新建; 朱涛; 王喜艳; 付靓; 杨乐; 魏德海

    2008-01-01

    Objective To study the characteristic and mechanism of fluid metabolism in acute re-action phase of the severe acute pancreatitis (SAP). Methods Twenty-three dogs were randomly divided into two groups:mild acute pancreatitis (MAP) group (n=8) and SAP group (n= 15).The model of a-cute pancreatitis was made by injecting bile into main pancreatic duct. All the dogs were subjected to infu-sion therapy 1-5 days after model establishment. The plasma concentrations of Na+ and K+ ,red cell bema-tocrit,the plasma levels of aldosterone hormone and angiotensin Ⅱ were measured. The total incoming and excreting fluid and the total amount of isolation fluid were recorded. Results K+ concentration in SAP group had no significant change,and Na+ concentration was increased to (152.8±5.2) mmol/L at the first day ,decreased on the second day. The fluid output of 15 dogs was leas than the fluid input during the experiment period,and fluid sequestration at 48 h and 72 h was (1341±373) ml and (1998±510) ml respectively. There was significant difference between MAP and SAP groups (P < 0.05). The levels of plasma ALD and Ang Ⅱ were increased significantly in SAP group at the first day after the operation as compared with MAP group (P < 0.05). Both of them were declined at the second and third day, but higher than those preoperation. Conclusion The early body fluids metabolic disorder of the SAP mainly concen-trates in the capacity and concentration. The amount of the output is remarkably less than that of the input and fluid sequestration is increased continuously. The decline of the renal excretion function, which cannot play a fully role in regulating fluid metabolism,may be the key in metabolic disorder.%目的 探讨重症急性胰腺炎早期体液代谢的特点和机制.方法 取杂种犬23条分两组:轻症急性胰腺炎组(MAP组)8条和重症急性胰腺炎组(SAP组)5条,采用自身胆汁逆行主胰管注射法制模.制模后第1~5天每日补液,测定血浆Na+

  3. Research on Characteristics of Transformer Differential Current for Different Phase Compensation Methods%不同相位补偿方式下变压器差流特性研究

    Institute of Scientific and Technical Information of China (English)

    孙向飞; 束洪春

    2013-01-01

    研究了励磁涌流条件下,不同相位补偿方式对变压器差动保护差流二次谐波含量的影响.从推导空载合闸磁链表达式出发,分析影响励磁涌流的因素,理论分析了y→△与△→Y两种相位补偿方式对变压器差动保护中差流的二次谐波含量影响的差异,并重点分析了出现对称性涌流情况下的二次谐波含量.在此基础上,对比研究了这两种电流相位补偿方式对二次谐波比励磁涌流识别判据的影响.根据现场录波数据,通过实际数据分别计算分析了相电流及两种相位补偿方式下所得差流的二次谐波比.理论分析和实际计算表明,经Y→△相位补偿后出现的对称性涌流,其二次谐波含量并不低;△→Y相位补偿方式下采用分相闭锁保护也存在问题,也不宜利用未经补偿的相电流计算闭锁判据中的二次谐波比.%The influence of different phase compensation methods on the ratio of second harmonic in differential current for transformer is investigated under magnetizing inrush.Firstly,the flux linkage expression of switching on without load is deduced and influencing factors of inrush current are analyzed.Then this paper compares the differences between two phase compensation methods of Y→ △ and △→Y,with an emphasis on the analysis of the ratio of second harmonic of symmetric inrush.Using inrush waveform of a real transformer,the ratio of second harmonic of phase current and that of differential current under two kinds of phase compensation methods are calculated respectively.Furthermore,based on the calculation results,the effect of two kinds of phase compensation methods on the inrush current identification is proved.The analysis and calculation results show that the ratio of second harmonic of symmetric inrush caused by phase compensation methods,from star to delta,is not low.Moreover,the split-phase blocking scheme should not be adopted for differential protection of from delta

  4. 水平长直管内油水两相流流动特性实验研究%An Experimental Study on the Flow Characteristics of Oil-Water Two-Phase Flow in Horizontal Straight Pipes

    Institute of Scientific and Technical Information of China (English)

    刘文红; 郭烈锦; 吴铁军; 张西民

    2003-01-01

    The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superficial velocity ranges of oil and water were: 0.04-1.2 m.s-1 and 0.04-2.2 m.s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

  5. Phase behaviour of transfer functions in vibrating systems

    DEFF Research Database (Denmark)

    Zhu, Jianyuan; Ohlrich, Mogens

    1998-01-01

    This paper investigates the applicabilities of pole-zero models and wave propagation theory in estimating the phase characteristics of vibrating systems. The measured phase spectra are compared with the estimated reverberant phase limit and wave propagation phase. The relations between transfer...... on frequency in this band, but from the transition frequency and onwards the phase increases only with the square root of frequency. This behaviour is characteristic for free propagating waves....

  6. Preparation and characteristics of composite expanded perlite of phase change paraffin wax%相变石蜡复合膨胀珍珠岩的制备与表征

    Institute of Scientific and Technical Information of China (English)

    郭振华; 马康; 兰北辰

    2012-01-01

    Through Scanning Electron Microscope(SEM) and Differential Scanning Calorimeter(DSC) with vacuum absorption method, the pa- per studies micro-structure and thermal performance of composite material. The experimental results show that : all micro-hole of expanded perlite rock can be filled with paraffin wax absorbed, the phase change enthalpy of composite phase energy-storing material is lower than that of single phase change of paraffin wax, the optimal quality ratio of paraffin wax and expanded perlite rock is 3: 1.%通过扫描电子显微镜(SEM)与差示扫描量热仪(DSC),采用真空吸附法对复合材料微观结构及热性能进行了研究。试验结果表明:经过吸附后,膨胀珍珠岩的所有微孔基本被石蜡填充;复合相变储能材料的相变焓相对于单一石蜡的相变焓有所降低;石蜡与膨胀珍珠岩复合的最佳质量比为3:1。

  7. Non-Axial Characteristics of Strehl Ratio of Cubic Phase Mask in Wavefront Coding System%三次相位掩模板波前编码系统非轴向斯特雷尔比

    Institute of Scientific and Technical Information of China (English)

    范志刚; 陈守谦; 常虹; 许志高

    2011-01-01

    传统成像光学系统的点扩展函数(PSF)峰值位置在其光轴上,斯特雷尔比(SR)定义为有无像差轴向PSF强度之比,而波前编码系统在光瞳处相位变化为非旋转对称式,其PSF在像面上将产生偏移,利用PSF的轴向强度计算光学系统斯特雷尔比将不再适用.分析了三次相位掩模板PSF的位置偏移量,其是以焦面为对称轴的抛物线族.并在此基础上提出了适用于评价波前编码系统的非轴向斯特雷尔比(SRwc),分析了非轴向斯特雷尔比的变化特性,其幅值与相位板参量成反比.并利用非轴向斯特雷尔比研究了PSF的一致性及可恢复性问题,阐述了影响PSF一致性和可恢复性的因素.最后,提出了基于非轴向斯特雷尔比相位板参量的优化方法,该方法给出了相位板参量与系统一致性和可恢复性之间的定量关系.%For general imaging optical system, the peak position of point spread function (PSF) is located in the optical axis. Strehl ratio (SR) is defined as the ratio of on-axis values of PSF with and without aberrations, but PSF of wavefront coding system whose phase change in pupil plane is asymmetric has a shift in the image plane, so evaluation of wavefront coding system using traditional Strehl ratio is not appropriate. Shift value of PSF for cubic phase mask is carried out, which is a family of parabolas, whose focal plane is symmetrical axis. Based on this, nonaxial Strehl ratio of wavefront coding system is defined, whose different parameters are analyzed, and the magnitude of Strehl ratio is inversely proportional to parameter of phase mask. Non-axial Strehl ratio is used to evaluate consistency and recoverability of PSF. Finally, an evaluation method in order to optimize phase mask parameter is given, which can determine the relation between consistency and recoverability of PSF and phase mask parameter.

  8. Optical Modulation Characteristics and Applications of Liquid Crystal Televisions

    Science.gov (United States)

    1992-05-18

    than binary or ternary, phase filters . The phase modulation present in the LCTV can be isolated from the amplitude modulation to some degree with the...however, it is known that the LCTV was used to display only a 128 x 128 binary phase filter . The research presented in this report will soon be...extended to use the analog phase modulation characteristics of LCTVs to encode an analog phase filter . Little attention has been given to using phase-encoded

  9. DESIGN THREE PHASE OVERCURRENT RELAYS

    Directory of Open Access Journals (Sweden)

    Mohammed Y Suliman,

    2013-05-01

    Full Text Available  A new design of three phase overcurrent relay described in this paper. The performance of the new design shows the ability to obtain any shape of characteristic with high accuracy and distinguish between transient and steady state fault. This design used more precise and flexible model Sachdev linear model for get any characteristic, also fast measurement theory to measure load current for less than half cycle and good hardware system design controlled by Pentium version 4 processor.

  10. Phase Vocoder

    Directory of Open Access Journals (Sweden)

    J.L. Flanagan

    2013-08-01

    Full Text Available A vocoder technique is described in which speech signals are represented by their short-time phase and amplitude spectra. A complete transmission system utilizing this approach is simulated on a digital computer. The encoding method leads to an economy in transmission bandwidth and to a means for time compression and expansion of speech signals.

  11. Temperature Distribution and Exergy Transfer Characteristics of the Single-phase Counter Flow Heat Exchanger%单相逆流换热器温度分布及(火用)传递特性的研究

    Institute of Scientific and Technical Information of China (English)

    张明智; 魏博; 孙刚; 任敬科

    2009-01-01

    Using the developing method of logarithmic mean temperature in counter flow heat exchanger without phase change for reference, the temperature distribution of fluid, inner wall and outer wall of the heat exchanger without phase change was developed. Then taking the superheating section of certain highpressure heater as an example, the exergy transfer coefficients in the process of heat transfer from steam to outer wall of the tube and from inner wall of the tube to feedwater were calculated separately on the basis of the first, the second thermodynamic laws and the non-equilibrium thermodynamics theory. The heat transfer performance of the shell and tube heat exchanger without phase change was analyzed from the view of exergy transfer, providing the theory evidence for structure optimization of heat exchanger.%借鉴无相变逆流换热器对数平均温度的推导方法,导出了无相变换热器中流体及换热管内、外壁的温度分布,并基于热力学第一、第二定律及非平衡热力学理论,以某高压加热器过热段为例,分别求出了换热过程中蒸汽至管外壁和管内壁至给水的传(火用)系数,从(火用)传递的角度分析了无相变管壳式换热器的换热性能,为优化换热器结构提供了理论参考依据.

  12. Imaging characteristic of dual-phase {sup 18}F-florbetapir (AV-45/Amyvid) PET for the concomitant detection of perfusion deficits and beta-amyloid deposition in Alzheimer's disease and mild cognitive impairment

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Kun-Ju; Hsiao, Ing-Tsung; Hsieh, Chia-Ju; Wey, Shiaw-Pyng; Yen, Tzu-Chen [Linkou Chang Gung Memorial Hospital and University, Department of Nuclear Medicine and Molecular Imaging Center, Taoyuan (China); Chang Gung University, Department of Medical Imaging and Radiological Sciences and Healthy Aging Research Center, Taoyuan (China); Hsu, Jung-Lung [Linkou Chang Gung Memorial Hospital, Section of Dementia and Cognitive Impairment, Department of Neurology, Taoyuan (China); Taipei Medical University, Graduate Institute of Humanities in Medicine, Taipei (China); Huang, Chin-Chang; Huang, Kuo-Lun [Linkou Chang Gung Memorial Hospital and University, Department of Neurology, Taoyuan (China)

    2016-07-15

    We investigated dual-phase {sup 18}F-florbetapir (AV-45/Amyvid) PET imaging for the concomitant detection of brain perfusion deficits and beta-amyloid deposition in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (MCI), and in cognitively healthy controls (HCs). A total of 82 subjects (24 AD patients, 44 MCI patients and 14 HCs) underwent both dual-phase {sup 18}F-AV-45 PET and MRI imaging. Dual-phase dynamic PET imaging consisted of (1) five 1-min scans obtained 1 - 6 min after tracer injection (perfusion {sup 18}F-AV-45 imaging, pAV-45), and (2) ten 1-min scans obtained 50 - 60 min after tracer injection (amyloid {sup 18}F-AV-45 imaging). Amyloid-negative MCI/AD patients were excluded. Volume of interest analysis and statistical parametric mapping of pAV-45 and {sup 18}F-AV-45 images were performed to investigate the perfusion deficits and the beta-amyloid burden in the three study groups. The associations between Mini-Mental State Examination (MMSE) scores and global perfusion deficits and amyloid deposition were investigated with linear and segmental linear correlation analyses. HCs generally had normal pAV-45 findings, whereas perfusion deficits were evident in the hippocampus, and temporal, parietal and middle frontal cortices in both MCI and AD patients. The motor-sensory cortex was relatively preserved. MMSE scores in the entire study cohort were significantly associated with the degree of perfusion impairment as assessed by pAV-45 imaging (r = 0.5156, P < 0.0001). {sup 18}F-AV-45 uptake was significantly higher in AD patients than in the two other study groups. However, the correlation between MMSE scores and {sup 18}F-AV-45 uptake in MCI patients was more of a binary phenomenon and began in MCI patients with MMSE score 23.14 when {sup 18}F-AV-45 uptake was higher and MMSE score lower than in patients with early MCI. Amyloid deposition started in the precuneus and the frontal and temporal regions in early MCI, ultimately

  13. Viscoelastic Phase Separation of Protein Solutions

    Science.gov (United States)

    Tanaka, Hajime; Nishikawa, Yuya

    2005-08-01

    In addition to the known behavior of normal phase separation and gelation, we report novel phase-separation behavior of protein solutions as their intermediate case. A network structure of the protein-rich phase may be formed even if it is the minority phase, contrary to the conventional wisdom. This behavior is characteristic of viscoelastic phase separation found in polymer solutions. This kinetic pathway may play crucial roles in the complex phase ordering of protein solutions, in particular, protein network formation in biological systems and foods.

  14. Formation and evolution characteristics of bcc phase during isothermal relaxation processes of supercooled liquid and amorphous metal Pb%过冷液态和非晶态金属Pb等温驰豫过程中bcc相的形成和演变特性

    Institute of Scientific and Technical Information of China (English)

    周丽丽; 刘让苏; 田泽安; 刘海蓉; 侯兆阳; 朱轩民; 刘全慧

    2011-01-01

    The formation and evolution characteristics of bcc phase during the isothermal relaxation processes for supercooled-liquid and amorphous Pb were investigated by molecular dynamics simulation and cluster-type index method (CTIM). It is found that during the relaxation process,the formation and evolution of bcc phase are closely dependent on the initial temperature and structure.During the simulation time scale,when the initial temperature is in the range of supercooled liquid region,the bcc phase can be formed and kept a long time; while it is in the range of glassy region,the bcc phase can be formed at first and then partially transformed into hcp phase; when it decreases to the lower one,the hcp and fcc phases can be directly transformed from the glassy structure without undergoing the metastable bcc phase. The Ostwald's "step rule" is impactful during the isothermal relaxation process of the supercooled and glassy Pb,and the metastable bcc phase plays an important role in the precursor of crystallization.%采用分子动力学模拟方法和团簇类型指数法,对过冷液态和非晶态金属Pb在等温驰豫过程中bcc相的形成和演变特性进行研究.结果表明:bcc相的形成和演变密切依赖等温驰豫过程的初始温度和初始结构,在过冷液态区,bcc相很容易形成并在模拟时间范围内保持稳定;而在非晶态区,bcc相先形成并随后部分转变为hcp相,当驰豫的初始温度在较低的153 K和113 K时,hcp和fcc相不经历亚稳bcc相而直接在非晶态结构中形成;这说明Ostwald的"步进原则"在过冷液态和非晶态Pb等温驰豫过程中是有效的,并且,亚稳bcc相起到重要的晶化前驱的作用.

  15. 变压器三相涌流波形特征分析及判别方法研究%Analysis and Assessment Methods of Waveform Characteristics of Three-Phase Transformer Inrush Current

    Institute of Scientific and Technical Information of China (English)

    卓元志; 李康; 赵斌; 韩斌; 赵雪沉璎

    2012-01-01

    With two big waveform characteristics of the transformer excitation inrush current revealed, this paper makes full use of the waveform characteristics,and then proposes a method of distinguishing the transformer excitation inrush current and internal fault current. This method is based on the assumption that the inrush current waveform presents the spire concave arc characteristics and fault current presents the sine waveform characteristics, and in half a cycle samples values can find the extreme value point,frequency, forming the corresponding virtual sine wave. Judging the similarity between the closing current and the tectonic waveform in half-wave cycle can distinguish between the excitation inrush current and fault current. The simulation results show that this method can effectively and quickly remove the internal faults of the transformer, and is not influenced by the aperiodic current components.%在揭示变压器励磁涌流两大波形特征的基础上,充分利用波形特征,提出一种利用波形特征区分变压器励磁涌流和内部故障电流的方法,该方法基于涌流波形呈现出尖顶波的凹弧特征,而故障电流基本保持正弦波形特征,在半波周期内找到采样值的极值点及频率,构造出与之对应的虚拟正弦波形,通过判断合闸电流与构造波形在半波周期内的相似程度来区分励磁涌流和故障电流.仿真结果表明,该方法能够有效、快速切除变压器内部故障,并且不受电流非周期分量的影响.

  16. A MODEL FOR PREDICTING PHASE INVERSION IN OIL-WATER TWO-PHASE PIPE FLOW

    Institute of Scientific and Technical Information of China (English)

    GONG Jing; LI Qing-ping; YAO Hai-yuan; YU Da

    2006-01-01

    Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop (25.7 mm inner diameter,52 m long) are conducted. A new viewpoint is brought forward about the process of phase inversion in oil-water two-phase pipe flow. Using the relations between the total free energies of the pre-inversion and post-inversion dispersions, a model for predicting phase inversion in oil-water two-phase pipe flow has been developed that considers the characteristics of pipe flow. This model is compared against other models with relevant data of phase inversion in oil-water two-phase pipe flow. Results indicate that this model is better than other models in terms of calculation precision and applicability. The model is useful for guiding the design for optimal performance and safety in the operation of oil-water two-phase pipe flow in oil fields.

  17. Relation between the occurrence of Burnout and differential pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Shoji [Yokohama National University, Yokohama 240-8501 (Japan)]. E-mail: morisho@ynu.ac.jp; Fukano, Tohru [Kurume Institute of University, Fukuoka 830-0052 (Japan)]. E-mail: fukanot@cc.kurume-it.ac.jp

    2006-05-15

    If a flow obstacle such as a spacer is placed in a boiling two-phase flow within a channel, the temperature on the surface of the heating tube is severely affected by the existence of the spacer. Under certain conditions the spacer has a cooling effect, and under other conditions the spacer causes dryout of the cooling water film on the heating surface, resulting in burnout of the tube. The burnout mechanism near the spacer, however, remains unclear. In a previous paper (Fukano, T., Mori, S., Akamatsu, S., Baba, A., 2002. Relation between temperature fluctuation of a heating surface and generation of drypatch caused by a cylindrical spacer in a vertical boiling two-phase upward flow in a narrow annular channel. Nucl. Eng. Des. 217, 81-90), we reported that the disturbance wave has a significant effect on dryout occurrence. Therefore, in the present paper, the relation between dryout, burnout occurrence, and interval between two successive disturbance waves obtained from the differential pressure fluctuation caused by the disturbance waves passing by a spacer, is further discussed in detail.

  18. Nanoscale phase change memory materials.

    Science.gov (United States)

    Caldwell, Marissa A; Jeyasingh, Rakesh Gnana David; Wong, H-S Philip; Milliron, Delia J

    2012-08-01

    Phase change memory materials store information through their reversible transitions between crystalline and amorphous states. For typical metal chalcogenide compounds, their phase transition properties directly impact critical memory characteristics and the manipulation of these is a major focus in the field. Here, we discuss recent work that explores the tuning of such properties by scaling the materials to nanoscale dimensions, including fabrication and synthetic strategies used to produce nanoscale phase change memory materials. The trends that emerge are relevant to understanding how such memory technologies will function as they scale to ever smaller dimensions and also suggest new approaches to designing materials for phase change applications. Finally, the challenges and opportunities raised by integrating nanoscale phase change materials into switching devices are discussed.

  19. Closed Orbits in Phase Space

    Science.gov (United States)

    Murphy, Andrew; Haestad, Jace; Morgan, Thomas

    2015-09-01

    We report characteristics of closed classical orbits in an electric field in phase space produced in photoabsorption. Rydberg states of atomic and molecular hydrogen and helium are considered. The core potential used for the hydrogen molecule is an effective one electron one center core potential evaluated at the internuclear equilibrium distance. Poincare surfaces of section in phase space are generated by integrating the equations of motion in semiparabolic coordinates u = (r + z) 1 / 2 and v = (r - z) 1 / 2, and plotting the location in phase space (pv versus v) whenever u = 0, with the electric field in the z direction. Combination orbits produced by Rydberg electron core scattering are studied and the evolution in phase space of these combination orbits due to scattering from one closed orbit into another is investigated. Connections are made to measured laser photoabsorption experiments that excite Rydberg states (20 recurrence spectra. The phase space structures responsible for the spectra are identified.

  20. Two-phase characteristics of the feeding fluid of Cerro Prieto IV wells (Mexico) obtained by gas equilibrium; Caracteristicas bifasicas del fluido de alimentacion de pozos de Cerro Prieto IV (Mexico), obtenidas por equilibrio gaseoso

    Energy Technology Data Exchange (ETDEWEB)

    Barragan-Reyes, Rosa Maria; Arellano-Gomez, Victor Manuel; Portugal-Marin, Enrique [Instituto de Investigaciones Electricas (Mexico); De Leon-Vivar, Jesus [Comision Federal de Electricidad, Residencia General de Cerro Prieto, B.C (Mexico)

    2008-10-15

    The gas composition of fluids produced by CP IV geothermal wells from the Cerro Prieto field was studied in order to identify different types of fluids entering the wells by estimating their temperature and excess steam. A method based on the Fischer Tropsch reaction and H2S equilibrium with pyrite-pyrrhotite as mineral buffer (FTHSH3) was used. The results for the reservoir natural state indicated the presence of fluids with heterogeneous reservoir temperature (between 275 and 310 degrees Celsius) and excess steam values, which were found from negative (boiled liquid that has lost steam when flowing to the well) to one (steam phase with zero liquid saturation). The study for individual wells in which boiling processes were identified, showed that through time, the feeding fluids consist of a two-phase mixture with different liquid/steam proportions. Also, the results suggested that a steam phase could occur at CP IV which is added to the feeding fluid, depending on the operation conditions of the wells. The origin of this steam could be the boiling of the deeper liquid due to a pressure drop. [Spanish] Se estudio la composicion gaseosa de los fluidos producidos por pozos geotermicos del sector CP IV del campo de Cerro Prieto para tratar de distinguir aportes de fluidos diferentes mediante la estimacion de su temperatura de yacimiento y del exceso de vapor. Se utilizo un metodo de equilibrio gaseoso basado en la reaccion de Fischer Tropsch y el equilibrio combinado pirita-pirrotita (FT-HSH3). Los resultados obtenidos indican que en el estado inicial del yacimiento existen fluidos que muestran heterogeneidad en los valores de temperatura de yacimiento (entre 275 y 310 grados Celsius), asi como en el exceso de vapor con valores desde negativos (liquido que despues de ebullir ha perdido vapor en su trayecto hacia el pozo) hasta uno (vapor con cero saturacion de liquido). El estudio individual de los pozos con fenomenos de ebullicion muestra que a traves del tiempo

  1. Structure properties and relaxor characteristics of the phases transformation in BaTi{sub 0.5}(Fe{sub 0.33}Mo{sub 0.17})O{sub 3} perovskite ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Bourguiba, Fayçal, E-mail: fayssalbourguiba@gmail.com [Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences de Monastir, Monastir, 5019 (Tunisia); Dhahri, Ah.; Tahri, Tarek [Laboratoire de Physique appliqué, Département de physique, Faculté des sciences de, Sfax, 3018 (Tunisia); Dhahri, J. [Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences de Monastir, Monastir, 5019 (Tunisia); Abdelmoula, N. [Laboratoire des Matériaux Ferroélectriques (LMF), LR-Physique-Mathématiques et Applications, Université de Sfax, Faculté des Sciences (FSS), Route de Soukra km 3.5 B.P 1171, 3000, Sfax (Tunisia); Taibi, K. [Laboratoire de Science et Génie des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, Université des Sciences et de la Technologie Houari Boumediene BP32 El Alia, Bab Ezzouar, 16111, Alger (Algeria); Hlil, E.K. [Institut Néel, CNRS-Université J. Fourier, B.P. 166, 38042, Grenoble (France)

    2016-08-05

    The effect of replacing titanium by iron and molybdenum in the B site on the structural and physical properties of BaTi{sub 0.5}(Fe{sub 0.33}Mo{sub 0.17})O{sub 3} polycrystalline sample was investigated by X-ray diffraction, scanning electron microscopy (SEM) as well as dielectric characterizations. Crystal phase, microstructure, and dielectric property of the ceramic were examined. A single hexagonal perovskite structure with space group P6{sub 3}/mmc was obtained at 1400 °C and stabilized at room temperature. The microstructural study of the sintered pellets revealed that the plate-like grains are the typical grain morphologies in this ceramic. The temperature dependence of the dielectric properties was investigated in the frequency range 1 kHz to 1 MHz. Three dielectric relaxations were observed in the present ceramic at the temperature ranges of 330–473 K, 473–550 K and 650–800 K with a maximum in the dielectric permittivity (ε{sup ’}{sub r} ∼ 3518 at 443 K at 1 KHz, ε{sup ’}{sub r} ∼4335 at 502 K at 1 KHz and ε{sup ’}{sub r} ∼11,331 at 749 K at 1 KHz) that shifted to a higher temperature with increasing frequency. Temperature dependent variation of the dielectric constant showed a diffused phase transition which can be well described by fitting the modified Curie–Weiss relation, (1/ε{sup ‘}{sub r}–1/ε{sup ‘}{sub r,max})=(T–T{sub m}){sup γ}/C. - Highlights: • The BaTi{sub 0.5}(Fe{sub 0.33}Mo{sub 0.17})O{sub 3} ceramic was prepared by solid state reaction. • The sample crystallizes in the hexagonal P6{sub 3}/mmc structure. • Temperature dependency dielectric study showed relaxor kind phase transition for different temperature Regions.

  2. Analysis of the turbulence anisotropy characteristic in the interface of gas-liquid two phase flow in horizontal tubes%水平管内气液两相流界面湍流各向异性分析

    Institute of Scientific and Technical Information of China (English)

    邱国栋; 蔡伟华; 姜益强

    2016-01-01

    In order to explore how to choose the turbulence model of the gas-liquid two phase flow in a horizontal pipe, the guess that the turbulence of the interface of the gas-liquid two phase flow in a horizontal pipe is anisotropic was put forward. The emergence and development mechanism of the turbulence anisotropy in the interface was analyzed. It points out that the turbulence inertial force generated by the turbulence anisotropy in the interface is an important reason for the formation of annular flow in a horizontal tube, which was verified by comparing the simulation results of using the two-equation model and Reynolds stress model ( RSM) to simulate the same working condition of annular flow in a horizontal tube. On such basis, the basis of selecting turbulence model in gas-liquid two phase flow was discussed. The results show that the RSM model is adaptive for large gas-liquid shear stress in a horizontal pipe, while the two-equation model and RSM model are both adaptive for other conditions.%为探讨水平管内气液两相流湍流模型如何选择,提出水平管内气液两相流界面湍流为各向异性的猜想,分析了该界面湍流各向异性产生和发展的机理,指出界面湍流各向异性产生的湍流惯性力是水平管环状流形成的重要原因.通过比较二方程模型和雷诺应力模型( RSM)模拟同一个水平管环状流工况的结果来验证分析的正确性,在此基础上探讨了气液两相流湍流模型的选择依据.结果表明当水平管内气液剪切力较大时适合选用RSM模型,其他情况二方程模型和RSM模型均适用.

  3. Incommensurate phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Currat, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1996-11-01

    We review the characteristic aspects of modulated crystals from the point of view of inelastic neutron scattering. We discuss the phenomenological Landau theory of the normal-to-incommensurate displacive instability and its predictions concerning the fluctuation spectrum of the modulated phase. General results on the form of the normal-mode eigenvectors and on the inelastic scattering channels through which they couple to the probe are established using the superspace approach. We illustrate these results on a simple discrete model symmetry and we review available inelastic neutron scattering data on several displacively modulated compounds. (author) 21 figs., 73 refs.

  4. Structural characteristics of the new high-T/sub c/ superconducting phase Bi/sub 2/ Sr/sub 2/ Ca Cu/sub 2/ O/sub 8+x/

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo, E.; Orozco, E.; Fuentes-Maya, J.; Mendoza, A.; Gasga, J.R.; Martinez, L.; Perez, R.; Garcia, A.; Schabes, P.S.; Acosta, D.

    1988-01-01

    A structural characterization of the superconducting phases in Bi/sub 2/ Sr/sub 2/ Ca Cu/sub 2/ O/sub 8+x/ is carried out. X-ray measurements are in agreement with recently reported diffraction patterns indicating an orthorhombic structure with large c-axis parameter (/approx/ 30A). Twin boundaries which are commonly found in high-T/sub c/ superconducting compounds based on Y or rare earths are however not frequent in these new type of superconductors. Transmission Electron Microscope images show a layered type of structure and electron diffraction patterns which confirm the orthorhombic structure. The resistivity measurements show a large drop at 100/sup 0/K with a T/sub c/ of the order of 76/sup 0/K.

  5. 三相异步电机空载试验特性曲线拟合%Characteristic curve-fitting of ho-load test for three-phase asynchronous motor

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 郭颖达; 王志芳

    2011-01-01

    Data processing of motor type test has a problem of low precision of curve-fitting. This paper proposed a curve-fitting function and made a detailed discussion on how to discriminate original data and the function that fits no-load test. VC++ language is adopted to realize data discrimination and draw a characteristic curve of high precision.%针对处理电机试验数据时曲线拟合精度低的情况,提出了空载试验的拟合函数.详细讨论了对原始数据的甄别,以及适用于空载试验的函数,采用VC++实现数据甄别,绘制精度高的特性曲线.

  6. 矩形窄缝通道内单相水流动特性研究%Research on Characteristics of Single-Phase Water Flow in Narrow Rectangular Channel

    Institute of Scientific and Technical Information of China (English)

    幸奠川; 阎昌琪; 曹夏昕; 刘宇生; 谢清清

    2011-01-01

    A calculation formulation for laminar friction coefficient in narrow rectangular channel was obtained by theoretical analysis. Experiments have been made on flow characteristics in narrow rectangular channels with low aspect ratios, and the results show that the curve of friction coefficients in rectangular channel varying with Reynolds number is similar to that in round pipe. The conventional frictional correlations based on circular pipes are not available for rectangular channels, which depend on Reynolds numbers and aspect ratios, and the friction coefficient increases as the aspect ratio decreases. The experimental results agree well with the theoretical analysis. The effects of aspect ratios on frictional characteristics in laminar flow were explained by taking into account wetting perimeter and shear stress.%通过理论分析,得到了计算矩形窄缝通道单相层流摩阻系数的公式.对小高宽比矩形窄缝通道内的流动特性进行了实验研究,结果表明:矩形窄缝通道内单相摩阻系数随Re变化的曲线和圆管有相同的趋势,但圆管流动摩阻公式不适用于矩形窄缝通道.矩形通道内摩阻系数与Re和通道截面高宽比有关,通道高宽比越小,摩阻系数越大.实验结果和理论推导结论一致.从截面湿周和切向应力两方面解释了高宽比对矩形窄缝通道内单相水层流摩阻特性的影响机理.

  7. Precipitation of Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

    Institute of Scientific and Technical Information of China (English)

    Keisuke Yamamoto; Yoshisato Kimura; Yoshinao Mishima

    2004-01-01

    Ferritic heat resistant steels involving precipitation of intermetallic phases have drawn a growing interest for the enhancement of creep strength, while the brittleness of the intermetallic phases may lower the toughness of the alloy.Therefore, it is necessary to optimize the dispersion characteristics of the intermetallics phase through microstructural control to minimize the trade-off between the strength and toughness. The effects of α-Fe matrix substructures on the precipitation sequence, morphology, dispersion characteristics, and the stability of the intermetallic phases are investigated in Fe-Cr-W-Co-Si system. The precipitates of the Si-free Fe-10Cr-1.4W-4.5Co (at%) alloy aged at 873K are the R-phase but those of the Si-added Fe-10Cr-1.4W-4.5Co-0.3Si (at%) alloy are the icosahedral quasicrystalline phase. The precipitates in both the Si-free and Si-added alloys aged at 973K are the Laves phase. Matrix of the alloys is controlled by heat treatments as to provide three types of matrix substructures; ferrite, ferrite/martensite mixture and martensite. The hardening behavior of the alloys depends on the matrix substructures and is independent of the kinds of precipitates. In the alloys with ferrite matrix, the peak of hardness during aging at 873K shifts to longer aging time in comparison with that in the alloys with lath martensite matrix which contain numbers of nucleation sites.

  8. A RESEARCH ON PHASE CHARACTERISTICS OF THE HYDROCARBONS IN KUCHE PETROLEUM SYSTEM%库车油气系统烃类的流体相态特征研究

    Institute of Scientific and Technical Information of China (English)

    周兴熙

    2001-01-01

    22 oil and gas reservoirs have been found in Kuche petroleumsystem, being of various phase state types. According to the PVT experimental data and phase diagrams of 43 layers in these reservoirs, the hydrocarbons in Kuche petroleum system may be divided into 4 types and 7 subtypes. The results of studying the proved oil and gas reserves and predicted oil and gas resources indicate that the petroleum system is mainly rich in natural gas and the black oil and volatile oil sit in subordinate status, being mostly the associated and residual volatile oil formed by differentiation. Through comprehensively analyzing the physical properties and phase parameters of the oil and gas and the oil and gas resources in the system, it is clearly shown that the heavy hydrocarbon content and condensate content in natural gas are mainly controlled by the maturities of hydrocarbon source rocks;the reservoir formation conditions and exploration results (especially the discovery of giant Kela-2 gas field) indicate that the high-temperature cracking gas is of a good potential in the system,mainly distributing in the high- and post-maturity areas in the middle section of northern zone;and a wide region is occupied mainly by condensate gas and associated liquid hydrocarbon in the system.%库车油气系统已经发现了22个油气藏,其相态类型的多样性的特点十分鲜明,据这些油气藏的43层PVT实验数据和相图,可以把库车油气系统的烃类分为四类7种。探明的油气储量和油气资源预测结果表明该系统“整体富气”,黑油、挥发油处于从属地位,而且多为分异作用形成的伴生型和残余型的轻质油。综合分析油、气的物理性质、相态参数和系统的油气资源等地质条件,可明显地看出天然气的干湿程度及凝析油含量的高低主要受烃源岩成熟度控制;系统的成藏条件和勘探成果(特别是克拉2大气田的发现)都说明高

  9. 强内热源球床通道单相对流换热特性实验研究%Experimental Study on Single-Phase Convection Heat Transfer Characteristics of Pebble Bed Channels With Internal Heat Generation

    Institute of Scientific and Technical Information of China (English)

    孟现珂; 孙中宁; 周平; 徐广展

    2012-01-01

    The water-cooled pebble bed reactor core is the porous channels stacked with spherical fuel elements, having evident effect on enhancing heat transfer. Owing to the variability and randomness characteristics of it's interstice, pebble bed channels have a very complex heat transfer situation and have little correlative research. In order to research the heat transfer characters of pebble bed channels with internal heat source, electromagnetic induction heating method was adopted for overall heating the pebble bed which was composed of 8 mm diameter steel balls, and the internal heat transfer characteristics were researched. By comparing and analyzing the experimental data, the rule of power distribution and heat transfer coefficient with heat flux density, inlet temperature and working fluid' s Re were got. According to the experimental data fitting, the dimensionless average heat transfer coefficient correlation criteria was got. The fitting results are good agreement with the experimental results within difference.%球床水冷反应堆的堆芯为球形燃料元件堆积成的多孔通道,具有显著的强化换热作用.球床通道内的孔隙因具有多变性、随机性的特点,换热情况非常复杂,相关研究较少.为了研究含内热源球床通道内的换热特性,本文用直径为8 mm碳钢球堆积形成球床,以蒸馏水为工质,采用电磁感应加热方式对球床进行整体加热,研究球床通道内部的换热特性.通过对实验数据进行分析,得到了球床通道内部的功率分布和换热系数随热流密度、工质Re的变化规律,根据实验数据拟合得到了球床通道内平均换热系数的无量纲准则关联式,拟合结果与实验结果的相对偏差在12%以内,符合良好.

  10. Determination of aminopolycarboxylic acids in river water by solid-phase extraction on activated charcoal cartridges and gas chromatography with mass spectrometric detection. Method performance characteristics and estimation of the uncertainty.

    Science.gov (United States)

    Jiménez, Juan J

    2013-04-03

    A new sample preparation procedure to determine aminopolycarboxylic acids (ethylenediaminetetraacetic acid, EDTA, nitrilotriacetic acid, NTA, diethylenetriaminepentaacetic acid, DTPA, and cyclohexanediaminetetraacetic acid, CDTA) in river water is described. The procedure consists of the solid-phase extraction of the aminopolycaroxyllic acids on activated charcoal cartridges after increasing the ionic strength and acidifying the sample. The extract was eluted with methanol and the analytes were methylated in presence of BF3/methanol to determine them by GC with mass spectrometric detection. Recoveries were higher than 90% with good repeatabilities and inter-day precision for concentrations close to quantification limits (about 10 μg L(-1)) and higher. It has been verified that the proposed method is robust according to the Youden and Steiner test and free of matrix effects arisen from the presence of organic matter and iron(III) as deduced from statistical tests. A bottom-up approach was followed to estimate the uncertainty of the measured concentration. At concentrations close to 10 μg L(-1) the most relevant step of the method is the calculus of the interpolated concentration which has a high value of relative standard uncertainty.

  11. Dynamic theory of morphological characteristics of crystals of ɛ and γ phases, including Headley-Brooks orientation relationships upon the α-ɛ and α-ɛ-γ martensitic transformations

    Science.gov (United States)

    Kashchenko, M. P.; Chashchina, V. G.

    2015-10-01

    Different variants of the formation of martensite crystals upon the α-γ transformation caused by the tension-compression deformation of {110}α planes have been considered according to the dynamic theory of martensitic transformations. In contrast to previous works, here we take into account the deviation (angle θ) of the principal directions of deformation from the symmetry axes α. It has been shown that the requirement of the symmetry of the arrangement of atoms in the basal plane {0001}ɛ is satisfied in the range of angular deviations-arctan √ {2/3} ≤slant θ ≤slant arctan √ {2/3}. The algorithm for calculating the morphological characteristics is illustrated based on the example of an elastically isotropic medium, which does not require assigning concrete values of elastic moduli. The estimations performed make it possible, in particular, to explain the physical nature of the Headley-Brooks orientation relationships as a result of the inheritance of one of the variants of permissible material orientation relationships for the α-ɛ transformation in the course of the ɛ-γ transformation at θ 35°. The changes in the other morphological signs are also discussed.

  12. Numerical Modeling of the Performance of R22 and R290 in Adiabatic Capillary Tubes Considering Metastable Two-Phase Region--Flow Characteristics and Parametric Analysis of R22 and R290

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guobing; ZHANG Yufeng; HAO Hong

    2005-01-01

    Characteristics of R22 and its new alternative refrigerant R290 flowing through adiabatic capillary tubes are investigated based on the homogeneous model.Extensive flow variables along tube length such as pressure, temperature, viscosity, velocity, Reynolds number, friction factor and vapor quality etc are compared between the two fluids under the same operating condition. Two cases are considered, namely, either the same tube length or the same mass flow rate as inlet condition. The results show that the mass flow rate in the capillary tube of R290 is 40% lower than that of R22 due to the differences of physical properties between the two fluids. Further, a parametric analysis is performed and it appears that effects of geometric and thermodynamic parameters on mass flow rate of R290 are weaker than that of R22. When the condensing temperature is increased from 40 ℃ to 50 ℃, the mass flow rate for R22 is increased by 16%, while the increasing rate for R290 is 13%.

  13. Two-Phase Coupled Flow and Aerosols Dynamical Characteristics in the Fog Layer%雾层两相耦合流场及气溶胶颗粒物的动力学性质

    Institute of Scientific and Technical Information of China (English)

    李家骅; 丁珏; 翁培奋

    2013-01-01

    雾层气溶胶系统涉及复杂的动力学演变过程:碰撞、凝并、破碎、冷凝/蒸发、成核、沉积、表面化学反应等.因此,发展雾层与气相流场耦合的Eulerian-Lagrangian两相流模型、颗粒动力学及随机轨道模型,考虑重力、曳力、布朗力、Basset力等对颗粒相的作用.基于SIMPLE和多重Monte Carlo算法求解颗粒群平衡方程,自行开发了FAD程序首先对室内燃烧源细微颗粒物的扩散实验展开数值模拟,计算结果与实验数据吻合较好.将建立的模型和方法数值研究气溶胶污染物在雾环境中的输运过程,分析雾消散阶段颗粒相浓度、平均尺度的时空分布.结果显示:当时间演化至60 min,雾滴的平均尺度减小到初始的65.67%,而气溶胶颗粒最大数目对应的尺度为0.006 μm.%The complex dynamic evolution processes exist in the fog layer, which involve collision,coag-ualtion,breakage, condensation / evaporation, nucleation, deposition and surface chemical reaction. So, with considering effects of gravity, drag force, brownian force, basset forces on the particles, the Euleri-an-Lagrangian two-phase coupled flow model, particle dynamics models and stochastic trajectory model were developed. The SIMPLE scheme was used for the fluid phase, while Particle Balance Equation (PBE) of aerosols was solved by Multi-Monte Carlo method. Firstly, the FAD (Fog-Aerosol-Dynamics) program was developed for simulating the experiment research on fine particles diffusion from indoor combustion sources, and the computed results were accordance with experimental data. Then, the transport process of aerosol particles in fog environment was studied numerically. Moreover, particle concentration, temporal and spatial distributions for particle average scale were analyzed during fog dissipation stage. The study results show for the time evolution to 60 min, average scale of fog droplet is reduced to 65.67% of the initial scale, and the scale of

  14. Electrochemical Characteristics and Li+ Ion Intercalation Kinetics of Dual-phase Li4Ti5O12/Li2TiO3 Composite in Voltage Range of 0−3 V

    KAUST Repository

    Bhatti, Humaira S

    2016-04-20

    Li4Ti5O12, Li2TiO3 and dual-phase Li4Ti5O12/Li2TiO3 composite were prepared by sol-gel method with average particle size of 1 µm, 0.3 µm and 0.4 µm, respectively. Though Li2TiO3 is electrochemically inactive, the rate capability of Li4Ti5O12/Li2TiO3 is comparable to Li4Ti5O12 at different current rates. Li4Ti5O12/Li2TiO3 also shows good rate performance of 90 mA h g-1 at high rate of 10 C in voltage range of 1−3 V, attributable to increased interfaces in the composite. While Li4Ti5O12 delivers capacity retention of 88.6 % at 0.2 C over 50 cycles, Li4Ti5O12/Li2TiO3 exhibits no capacity fading at 0.2 C (40 cycles) and capacity retention of 98.45 % at 0.5 C (50 cycles). This highly stable cycling performance is attributed to the contribution of Li2TiO3 in preventing undesirable reaction of Li4Ti5O12 with the electrolyte during cycling. CV curves of Li4Ti5O12/Li2TiO3 in 0−3 V range exhibit two anodic peaks at 1.51 V and 0.7−0.0 V, indicating two modes of lithium intercalation into the lattice sites of active material. Owing to enhanced intercalation/de-intercalation kinetics in 0−3 V, composite electrode delivers superior rate performance of 203 mAh/g at 2.85 C and 140 mAh/g at 5.7 C with good reversible capacity retention over 100 cycles.

  15. 45 kVA单相高温超导变压器交流损耗特性研究%AC LOSS CHARACTERISTICS OF A 45kVA SINGLE-PHASE HTS TRANSFORMER

    Institute of Scientific and Technical Information of China (English)

    王银顺; 赵祥; 韩军杰; 李会东; 关颖; 包庆; 肖立业; 林良真; 朱志芹

    2007-01-01

    本文研究以多芯不锈钢加强Bi2223/Ag带材绕制的45 kVA单相高温超导变压器的交流损耗特性.变压器绕组置于具有室温孔径的环形玻璃钢杜瓦内,铁芯穿过杜瓦室温孔径以保证铁芯与绕组分离并工作于室温环境.在77 K和工频下,基于Bean模型和绕组中的磁场分布计算了绕组的交流损耗,计算结果与传统电测法和热测法测量的变压器交流损耗结果一致;表明在77K绕组中交流损耗以磁滞损耗为主,涡流损耗和耦合损耗可以忽略不计.%This paper describes the AC losses in windings of a single-phase model 45kVA (HTS) transformer woundwith stainless steel-enforced multifilamentary Bi2223/Ag tapes. The windings were placed in an electrical insulation toroidal cryostat with room temperature bore for iron core. AC losses induced in the windings were theoretically estimated based on Bean-model and magnetic field distribution, which are good agreement with the actual ones measured by conventional electrical and calorimetric methods at rated current operation and power frequency 50Hz in liquid nitrogen of 77K. Based the calculated and measured results, it is shown that the hysteretic loss in windings is dominant, the eddy current and coupling loss are negligible.

  16. Research on Phase Change Materials and Thermal Release Characteristic of Thermal Storage by Using Auto Waste Heat%汽车余热利用蓄能材料及其释热特性试验研究

    Institute of Scientific and Technical Information of China (English)

    高淳; 王国华; 张天时; 矫振伟

    2011-01-01

    Temperature change characteristic and thermal storage ability of barium hydroxide octahydrate and paraffin during thermal storage are compared, and the heat release ability in the low temperature of barium hydroxide octahydrate under low temperature is studied. The results show that compared with paraffin, barium hydroxide octahydrate has better heat conductivity and latent heat of fusion, which make it has faster and greater transient heat-absorption capacity, furthermore, it shows superior thermal storage capacity in greater temperature difference; barium hydroxide octahydrate has obvious function in temperature rise during heat release under low temperatures, and has more heat release in lower temperature environment.%比较了石蜡和八水氢氧化钡两种材料在蓄热过程中的温变特性和吸热能力,并研究了低温环境下八水氢氧化钡蓄热器在放热过程中的低温释热性能.结果表明,与石蜡相比,八水氢氧化钡蓄热材料更高的导热性能和熔解潜热使它具有更快和更大的瞬时吸热能力,并在初期的大温差下显现出更好的蓄热特性:八水氢氧化钡用于低温环境释热过程的温升作用显著,且在更低的低温环境下具有相对较高的放热总量.

  17. C, N and P stoichiometric characteristics in leaves of Suaeda salsa during different growth phase in coastal wetlands of China%滨海盐地碱蓬不同生长阶段叶片C、N、P化学计量特征

    Institute of Scientific and Technical Information of China (English)

    李征; 韩琳; 刘玉虹; 安树青; 冷欣

    2012-01-01

    盐地碱蓬(Suaeda salsa)是滨海湿地典型植被之一,研究其化学计量特征变化对于了解滨海湿地植被健康状况具有重要意义.该文比较了盐地碱蓬生长期、成熟期和衰退期内叶片C、N、P营养元素的化学计量特征,并做了相关性分析.结果表明,叶片C含量在不同生长阶段差异性显著,生长期最低,衰退期最高;叶片N含量在衰退期较生长期和成熟期显著降低;叶片P含量较为稳定,在不同生长阶段无显著性差异.C∶N、C∶P在植物整个生长发育期内呈现逐渐增大的趋势,而N∶P表现出逐渐减小的趋势.相关性分析显示,在盐地碱蓬3个不同的生长阶段,C∶N和C∶P与相应的N、P含量呈显著负相关,随着N、P的变化以对数方程的形式减小;N含量与P含量之间呈显著正相关,体现了植物体内两营养元素含量需求变化的相对一致性.同时发现,N元素已经成为滨海湿地盐地碱蓬生长发育过程中的主要限制性因子.%Aims Suaeda salsa is a typical species in coastal wetlands, and understanding change in its stoichiometric characteristics would help to assess its health status and target conservation efforts. We investigated which nutrient factor restricts its growth and proposed theories for protecting and managing coastal wetland by comparing the C, N and P stoichiometric characteristics of S. salsa in different growth periods. Methods We collected 5. salsa leaves in different growth phases from June to November 2010 in Yancheng coastal wetlands, Jiangsu Province. The C, N and P contents of the leaves were measured. Data were analyzed by correlation analysis between N content and C:N and P content and C:P. N content and P content were also analyzed. Important findings Leaf C content of S. salsa had significant differences among three different growth phases, with the lowest in the growth phase and the highest in the decline phase. Leaf N content in the decline phase is

  18. An Inquiry into the Phases of Matter

    Science.gov (United States)

    Young, Sarah

    2010-01-01

    The "What's the "matter" With XOD" activity addresses students' misconceptions and refines their ideas about phases of matter. This activity introduces the characteristics for solids, liquids, and gases, and begins a discussion about physical and chemical changes and how matter can cycle through different phases. Depending on class size and…

  19. 谐振接地系统单相接地故障频谱特征分析%Frequency Spectrum Characteristic Analysis of Single-phase Grounding Fault in Resonant Grounded Systems

    Institute of Scientific and Technical Information of China (English)

    张海申; 何正友; 张钧

    2012-01-01

    基于谐振接地系统单相接地故障暂态等值电路,从理论上详细分析了故障电阻变化时系统暂态特性的变化情况,得出在故障电阻较小时系统处于欠阻尼状态,随着故障电阻的增大,系统进入过阻尼状态,最后又过渡到另一种等值电路下的欠阻尼状态。建立了含电缆线路的谐振接地系统模型,仿真分析了电缆线路的引入,以及故障初相角、故障距离、故障电阻变化时,暂态零序电流及其频谱特征的变化规律。仿真结果表明:电缆线路的引入将使暂态电流频谱主成分向低频段移动;故障电阻的大小对含电缆线路的谐振接地系统单相接地故障暂态电流频谱特征影响很大。%Based on the equivalent circuit of a resonant grounded system,the changes of the transient characteristics are analyzed theoretically when the fault resistance changes.The study indicates that the circuit is under-damped firstly,then it enters the damping state,and finally makes the transition to under-damped state.A resonant circuit model with cables is established,and the changing law of the zero-sequence transient current spectrum is analyzed when the cables are added to the distribution network and when the fault angle,fault resistance and fault distance are changed.Simulation results show that the adding of cables makes the spectrum of zero-sequence transient current move to a lower-band.Fault resistance has great influence on the spectrum of zero-sequence transient current.

  20. Z形狭缝内两种工质沸腾汽液两相特性分析%Study on Gas-liquid Two-phase Flow Characteristics of Two Kinds of Media in Z-shaped Channels

    Institute of Scientific and Technical Information of China (English)

    郭雷; 张树生; 程林

    2011-01-01

    为深入探索狭缝通道内沸腾换热机制,对2种不同液体在Z形狭缝通道内的沸腾汽液两相流动展开研究.利用数值模拟和自编程的方法分析汽泡生成、长大和脱离的过程,通过几何重构和界面追踪获取相界面移动和变化对系统内压降以及平均表面换热系数的影响,计算中考虑了重力、表面张力和黏性的作用.发现液体黏性的不同对汽泡生长方式和汽泡形态产生很大影响,黏性较小的液体产生汽泡的脱离直径较小,汽泡脱离频率高:表面张力和液体黏性对流动沸腾系统压降都具有较大影响;液体比热和沸点的不同导致换热系数有较大差别;结果与实验数据吻合良好,均表明水沸腾换热系数高于乙醇,Z形通道强化换热效果明显.%To explore the boiling heat transfer mechanism in narrow channels, gas-liquid two-phase flow in z-shaped narrow channels was studied with two different types of media. The bubble generation, growth and departure processes were analyzed using numerical simulation and self-programming. The influence of interface movements and changes on internal pressure difference and average surface heat transfer coefficient was investigated by using geometry reconstruction and interface tracking, taking into account gravity, surface tension and viscosity during calculation. The results show that the viscosity has great influence on generation modes and shapes of bubbles, that is, the lower the viscosity is, the smaller the diameter is when the bubble departs with a higher frequency. In addition, surface tension and viscosity significantly impact the pressure drop of boiling system, and different specific heat and boiling point values result in different heat transfer coefficients. The simulation results in this paper match well with the experimental data revealed in other sources, both show that the heat transfer coefficient of water is higher than that of ethanol and z-shaped channels have

  1. Characteristic analysis and diagnostic value of spiral CT multi-phase enhanced scan for hepatic abscess%肝脓肿螺旋CT多期增强扫描的特征分析及诊断价值

    Institute of Scientific and Technical Information of China (English)

    刘福尧

    2012-01-01

    Objective To investigate the CT features of hepatic abscess,in order to improve the diagnostic accuracy.Methods The data of 21 cases of liver abscess pathologically or clinically confirmed were retrospectively analyzed,all cases underwent unenhanced and enhanced scans.Results Among the 21 patients,35 lesions,single lesion in 17 cases and multiple lesions in 4 cases,tumor diameters ranged from 1.5-14.7 cm,with an average of 6.5 cm.Left lobe of liver lesions in 9 cases,right lobe of liver lesions in 26 cases,form class round in 21 cases,irregular-shaped in 14 cases.Scan showed low density lesions in the liver,5 lesions with uniform density,30 lesions with uneven density,of which two lesions containing gas.Thirty-one lesions with fuzzy realm,4 lesions with part fuzzy and part clear realm.By multi-phase check,there were 17 cases of typical liver abscess,in which,1 with single ring,13 with double rings,3 with 3 rings,18 cases of atypical liver abscess.Conclusions The recognition of CT features of dynamic enhanced scan can help to improve the diagnostic accuracy.%目的 探讨肝脓肿的CT特性,提高诊断准确性.方法 回顾性分析经临床治疗或粗针穿刺证实的肝脓肿21例的资料,所有病例均经平扫和强化扫描.结果 21例共35个病灶,单发17例,多发4例,病灶直径1.5 ~14.7cm,平均6.5 cm.病灶位于肝左叶9个,肝右叶26个.形态类圆形21个,不规则形14个.平扫表现为肝内低密度灶,5个病灶密度均匀,30个病灶密度不均匀,其中2个病灶内含气.病灶境界模糊31个,部分模糊、部分清晰4个.经多期增强检查,典型肝脓肿17个,其中单环1个,双环13个,三环3个.不典型肝脓肿18个.结论 认识动态增强CT特征,有助于提高诊断准确性.

  2. Adsorption Characteristics of 2,4-Dimethyphenol by Using Zeolite in Aqueous Phase%沸石分子筛对水中2,4-二甲基苯酚的吸附特性研究

    Institute of Scientific and Technical Information of China (English)

    魏健; 孔明昊; 宋永会; Jean-Stéphane PIC; 范冬琪

    2015-01-01

    以沸石分子筛为吸附剂,采用批次试验,研究静态吸附对水中2,4-二甲基苯酚(2,4-DMP)的吸附去除效果,比较了3种不同类型的沸石分子筛对2,4-DMP的吸附性能,选择其中吸附性能最好的沸石分子筛FAU-Y为吸附剂,分别考察了溶液初始pH、吸附剂投加量对吸附效果的影响,并对吸附动力学和吸附等温线进行了分析。结果表明,FAU-Y对2,4-DMP具有较大的吸附量,在2,4-DMP初始浓度为250 mg∕L,溶液初始pH为5.2,吸附剂投加量为5.0 g∕L时,室温条件下反应24 h可以达到吸附平衡状态,饱和吸附容量为48.22 mg∕g;初始pH为2.0~9.3时,对FAU-Y吸附2,4-DMP没有明显影响;吸附动力学和吸附等温线分析结果表明,二级动力学能更好地描述FAU-Y对2,4-DMP的吸附,Langmuir-Freundlich吸附等温线对吸附平衡数据的拟合优于Langmuir吸附等温线和Freundlich吸附等温线。%The adsorption removal of 2,4-dimethyphenol (2,4-DMP) in aqueous phase was investigated by using zeolite in a batch statistic adsorption system .The 2,4-DMP adsorption capabilities of three different zeolites were compared , and FAU-Y zeolite was chosen as the adsorbent for its best adsorption capabilities .The effects of initial pH and adsorbent dosage on 2 ,4-DMP adsorption were investigated respectively , and the adsorption kinetics and isotherms analyzed.The results showed that FAU-Y zeolite had high adsorption ability for 2, 4-DMP.The equilibrium of the adsorption process was established in about 24 h under the conditions of initial 2, 4-DMP concentration 250 mg∕L, initial pH 5.2, FAU-Y zeolite dosage 5.0 g∕L and temperature 20 ℃, with a saturated adsorption capability of 48.22 mg∕g.The initial pH from 2.0 to 9.3 had no significant influence on 2,4-DMP adsorption removal .The comparison of adsorption kinetic models showed that the adsorption process was

  3. Designing Of Pulse Phase-Locked Loops

    Directory of Open Access Journals (Sweden)

    A. A. Deryushev

    2006-01-01

    Full Text Available The paper considers pulse phase-locked loops (PPLL in which switching of structure and pa­rameters is used for improvement of dynamic and spectral characteristics Classification of existing switching algorithms is given in the paper. The paper proposes designing methodology that takes into account discrete and non-linear characteristics of the considered devices, and also requirements to synchronism, stability, speed, spectral characteristics, peculiarities of various switching algorithms. Practical approbation of the methodology has been carried out.

  4. 具有长期性特征的恐怖袭击与政府反恐多阶段重复博弈模型%Multi-phase Repeated Game Model between Terrorists and Government Anti-terrorism with Long-term Characteristic

    Institute of Scientific and Technical Information of China (English)

    刘德海; 邹华伟; 鲍雪言

    2016-01-01

    Abstract Terrorism represented by the “three forces” has become one of the long-term challenges for Chinese society, especially for Xinjiang region. Chinese anti-terrorism combat has the long-term characteristics. Considering the long-term characteristics of anti-terrorism, the paper builds a multi-phase repeated game model between government and terrorists, where Hausken and Zhuang’s dynamic game model has been taken as the stage game model. Using numerical experiments, we discussed the influence of the attention for future long-term income, the terrorists’ attacking cost, and the government’s valuation of the targeted asset on terrorists’ expected utility and the number of attacking time.%我国反恐问题具有长期性特征,以Hausken和Zhuang的动态博弈模型作为阶段博弈,在此基础上构建了政府防御方与恐怖分子的多阶段重复博弈模型。通过数值分析方法,分别讨论了双方对于未来长远收益重视程度、恐怖分子培训与实施袭击成本、政府防御目标估值等因素对于恐怖分子的期望收益和恐怖袭击次数的影响。

  5. Phase Transition in Loop Quantum Gravity

    CERN Document Server

    Mäkelä, Jarmo

    2016-01-01

    We point out that with a specific counting of states loop quantum gravity implies that black holes perform a phase transition at a certain characteristic temperature $T_C$. In this phase transition the punctures of the spin network on the stretched horizon of the black hole jump, in effect, from the vacuum to the excited states. The characteristic temperature $T_C$ may be regarded as the lowest possible temperature of the hole. From the point of view of a distant observer at rest with respect to the hole the characteristic temperature $T_C$ corresponds to the Hawking temperature of the hole.

  6. Clinical characteristics of 297 newly diagnosed Chinese HIV / AIDS patients

    Institute of Scientific and Technical Information of China (English)

    曹玮

    2014-01-01

    Objective To determine the clinical characteristics of HIV infected patients in China in order to improve early recognition and diagnosis of AIDS.Methods A total of297 newly diagnosed HIV/AIDS patients were enrolled in Peking Union Medical College Hospital(PUMCH)from January 2001 to December 2012,including 19 patients of primary phase,115 of asymptomatic phase and 163 of AIDS phase.Clinical characteristics of these patients were retrospectively analyzed.Results Two hundred and

  7. Fractional vortex dipole phase filter

    Science.gov (United States)

    Sharma, Manoj Kumar; Joseph, Joby; Senthilkumaran, Paramasivam

    2014-10-01

    In spatial filtering experiments, the use of vortex phase filters plays an important role in realizing isotropic edge enhancement. In this paper, we report the use of a vortex dipole phase filter in spatial filtering. A dipole made of fractional vortices is used, and its filtering characteristics are studied. It is observed that the filter performance can be tuned by varying the distance of separation between the vortices of the dipole to achieve better contrast and output noise suppression, and when this distance tends to infinity, the filter performs like a 1-D Hilbert mask. Experimental and simulation results are presented.

  8. 周期性热作用下相变材料内部相变传热特征实验研究%Experimental Study on the Characteristics of Phase Change Heat Transfer in PCM with Outside Periodic Heating and Cooling

    Institute of Scientific and Technical Information of China (English)

    冉茂宇; 赵红利

    2013-01-01

    为了揭示周期性热作用下相变材料内部相变传热特征,为建筑外表相变隔热设计和计算提供支撑,本文设计制作了能模拟太阳运行、提供周期性加热的装置,并将正18烷封装于塑料圆桶容器中,使容器底部和侧面绝热,制作了测试试件.利用热电偶和巡检仪自动记录了周期性热作用下相变材料内部各层温度的变化.测试结果表明,在稳定周期性热作用下,材料内部相变传热特征主要可表述为:1)材料在非稳态周期性相变传热阶段,各层温度在达到相变温度点之前,温度变化明显;相界面会随着周期性加热次数的增加间断性地向内部扩展;温度平均值和振幅值向稳态周期性相变传热时的平均值和振幅值靠近.2)材料在稳态周期性相变传热阶段,内部各点温度也表现出与外界热作用等周期性变化,温度振幅从外到内依次减小.这与发生在固体中的周期性传热特性类似.但材料内温度变化呈现折转现象,在温度明显升高前出现等温滞后,在温度降低时会出现等温冷却.这与发生在固体中的传热现象有很大的区别.3)材料在稳定周期性热作用下,内部不会出现多个相界面共存现象.4)空气流速对相变材料中温度振幅和相界面移动速率都有较大影响,提高空气流速可以降低温度振幅和减慢相变进程.这意味着当相变材料用于建筑外表进行相变隔热时,可以通过组织自然通风减少其用量.%In order to reveal the phase change heat transfer characteristics in PCM with outside steady periodic heating and cooling,and provide some suports for thermal insulation of building skin with PCM,an apparatus which can simulate the sun running and provide periodic heating was designed and made in this paper;a test specimen was also fabricated by encapsulating the octadecane into a plastic circular container with its bottom and side thermal insulation.The temperature variations

  9. Utilização da torta de girassol na alimentação de suínos nas fases de crescimento e terminação: efeitos no desempenho e nas características de carcaça Effects of feeding sunflower cake on performance and carcass characteristics, for swine in the growing and finishing phases

    Directory of Open Access Journals (Sweden)

    Mara Cristina Ribeiro da Costa

    2005-10-01

    Full Text Available Quarenta e oito suínos (Landrace x Large White com peso médio inicial de 22,69 kg (24 machos castrados e 24 fêmeas foram submetidos a quatro tratamentos (dietas com 0; 5; 10 e 15% de inclusão de TG, com o objetivo de avaliar o uso da torta de girassol (TG na alimentação de suínos nas fases de crescimento e terminação .Foram avaliados o ganho diário de peso (GDP, o consumo diário de ração (CDR e a conversão alimentar (CA durante as fases de crescimento I (20 a 50 kg de peso vivo, crescimento II (50 a 80 kg de peso vivo e terminação (80 a 100 kg de peso vivo. Ao abate, foram avaliados o peso (PC e o rendimento de carcaça (RC, a espessura de toucinho (ET, a profundidade do músculo Longissimus dorsi (PM, a área de olho de lombo (AOL, o comprimento de carcaça (CC, o rendimento (RCC% e a quantidade de carne na carcaça (QCC. Não houve diferença significativa no desempenho entre os tratamentos nos períodos avaliados. O efeito sexo foi significativo e em favor dos machos castrados apenas para o GPD em todas as fases, e para o CDR, na fase de terminação e no período total (20 a 100 kg de peso vivo. Para as características de carcaça, não houve diferença significativa entre os tratamentos e o efeito sexo foi significativo para a ET, QCC e CC, com maiores médias para os machos castrados, e para o RCC, com maior média para as fêmeas. A TG pode ser utilizada em até 15% de inclusão nas rações de crescimento e terminação, mantendo-se os mesmos índices de desempenho e qualidade da carcaça. A inclusão de 15% de TG foi a que apresentou o melhor índice de eficiência econômica.Forty-eight (24 barrows and 24 females Landrace x Large White pigs (averaging 22.69 kg of initial body weight were assigned to four treatments to evaluate the effect of feeding sunflower cake (SC on performance and carcass characteristics for swine in the growing and finishing phases. The following increasing dietary levels of sunflower cake (SC

  10. Cycle slipping in phase synchronization systems

    Science.gov (United States)

    Yang, Ying; Huang, Lin

    2007-02-01

    Cycle slipping is a characteristically nonlinear phenomenon in phase synchronization systems, which is highly dependent of the initial state of the system. Slipping a cycle means that the phase error is increased to such an extent that the generator to be synchronized slips one complete cycle with respect to the input phase. In this Letter, a linear matrix inequality (LMI) based approach is proposed and the estimation of the number of cycles which slips a solution of the system is obtained by solving a quasi-convex optimization problem of LMI. Applications to phase locked loops demonstrate the validity of the proposed approach.

  11. Basic characteristics of array of pulsatile jet

    Directory of Open Access Journals (Sweden)

    Vestfálová Magda

    2012-04-01

    Full Text Available The presented paper shows the results of measurement of basic characteristics of array of pulsatile jets which are used to enhance the efficiency of ejectors. Four pulsatile jets forms cross like structure where perpendicular couples are operating in two basic modes (a in phase and (b in antiphase. Paper presents phase averaged velocity profiles and velocity fields. All of the presented experiments are realized using hot wire anemometry method.

  12. Recognizing frequency characteristics of gas sensor array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel method based on independent component analyzing (ICA) in frequency domain to distinguish the frequency characteristics of multi-sensor system is presented. The conditions of this type of ICA are considered and each step of resolving the problem is discussed. For a two gas sensor array, the frequency characteristics including amplitude-frequency and phase-frequency are recognized by this method, and cross-sensitivity between them is also eliminated. From the principle of similarity, the recognition m...

  13. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    1996-01-01

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  14. The Mobile Phase Motion in Ascending Micellar Thin-Layer Chromatography with Normal-Phase Plates

    NARCIS (Netherlands)

    Boichenko, Alexander P.; Makhno, Iryna V.; Renkevich, Anton Yu.; Loginova, Lidia P.

    2011-01-01

    The physical chemical characteristics (surface tension and viscosity) of micellar mobile phases based on the cationic surfactant cetylpiridinium chloride and additives of alcohols (ethanol, 1-propanol, 1-butanol, 1-pentanol) have been obtained in this work. The effect of mobile phase properties on t

  15. The Mobile Phase Motion in Ascending Micellar Thin-Layer Chromatography with Normal-Phase Plates

    NARCIS (Netherlands)

    Boichenko, Alexander P.; Makhno, Iryna V.; Renkevich, Anton Yu.; Loginova, Lidia P.

    2011-01-01

    The physical chemical characteristics (surface tension and viscosity) of micellar mobile phases based on the cationic surfactant cetylpiridinium chloride and additives of alcohols (ethanol, 1-propanol, 1-butanol, 1-pentanol) have been obtained in this work. The effect of mobile phase properties on

  16. The Mobile Phase Motion in Ascending Micellar Thin-Layer Chromatography with Normal-Phase Plates

    NARCIS (Netherlands)

    Boichenko, Alexander P.; Makhno, Iryna V.; Renkevich, Anton Yu.; Loginova, Lidia P.

    2011-01-01

    The physical chemical characteristics (surface tension and viscosity) of micellar mobile phases based on the cationic surfactant cetylpiridinium chloride and additives of alcohols (ethanol, 1-propanol, 1-butanol, 1-pentanol) have been obtained in this work. The effect of mobile phase properties on t

  17. Phase-dependent modulation of corticospinal excitability during the observation of the initial phase of gait.

    Science.gov (United States)

    Takahashi, Makoto; Uchida, Natsuko; Yoshida, Mami; Liang, Nan; Nakazawa, Kimitaka; Sekikawa, Kiyokazu; Inamizu, Tsutomu; Hamada, Hironobu

    2014-12-01

    This study was undertaken to identify the temporal characteristics of corticospinal excitability of tibialis anterior muscle during the observation of the initial phase of gait. For this purpose, using transcranial magnetic stimulation, we recorded motor evoked potentials (MEPs) during the observation of the second step of an actor's first three steps of gait initiation with (complex gait) or without (normal gait) an obstacle and unstable surface. The results demonstrate that (1) MEPs during the observation of the initial phase of normal gait were significantly increased only at early swing phase, but not other phases (mid-swing, heel contact, mid-stance, and heel off) and (2) MEPs during the observation of the initial phase of complex gait were significantly increased at early swing and also at mid-swing and heel contact phases. These findings provide the first evidence that corticospinal excitability during the observation of gait, especially the initial phase, is modulated in phase- and motor-demanded-dependent manners.

  18. Retention Characteristics for Multiple-PhaseFluid Systems

    Directory of Open Access Journals (Sweden)

    Chia-Hsing Tsai and Gour-Tsyh Yeh

    2012-01-01

    Full Text Available The key objective of this paper is to point out that a widely used constitutive relationship between the degrees of saturation and capillary pressures for three-phasefluids over the past twenty five years has resulted in an undue constraint. To our knowledge, this constraint is neither physically justifiable nor is it theoretically supported. The discovery of the undue constraint leads this investigation to develop a viable parametric model to describe the constitutive relationship for a system of multiple fluids. Based on the physical consideration wherein fluid wettability follows a sequence, the proposed parametric model can be easily applied to any system of L arbitrary fluids. Three aspects are presented to confirm the plausibility and completeness of the model. First, the proposed closed-form expression of the saturation-capillary pressure head relationship is identical to van _ renowned model for two-phasefluid systems. Second, a constraint appearing in the widely used model is alleviated in the proposed model. Third, seven hypothetical examples are used to demonstrate that there is no need to impose the constraint on the sequence of capillary pressures. The results show the plausibility and completeness of the model for systems of multiple fluids. The proposed parametric model is a feasible analytic model which provides a generalized saturation-capillary pressure head relationship for any system with regard to multiple fluids. Hopefully, this study will pave a way for others to conduct experiments to validate the model further or develop other better non-constrained models based on experimental evidence.

  19. Accelerated life testing effects on CMOS microcircuit characteristics, phase 1

    Science.gov (United States)

    Maximow, B.

    1976-01-01

    An accelerated life test of sufficient duration to generate a minimum of 50% cumulative failures in lots of CMOS devices was conducted to provide a basis for determining the consistency of activation energy at 250 C. An investigation was made to determine whether any thresholds were exceeded during the high temperature testing, which could trigger failure mechanisms unique to that temperature. The usefulness of the 250 C temperature test as a predictor of long term reliability was evaluated.

  20. the steady-state performance characteristics of single phase transfer ...

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... The equivalent circuit of the machine was derived using the concept of double field ... are connected in series and energized from the utility supply, while the ..... where Zs = Rs + jxs, Zf is the parallel combina- tion of. ( Rr.

  1. Two-phase cooling fluids; Les fluides frigoporteurs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, A. [Institut National des Sciences Appliquees (INSA), 69 - Lyon (France)

    1997-12-31

    In the framework of the diminution of heat transfer fluid consumption, the concept of indirect refrigerating circuits, using cooling intermediate fluids, is reviewed and the fluids that are currently used in these systems are described. Two-phase cooling fluids advantages over single-phase fluids are presented with their thermophysical characteristics: solid fraction, two-phase mixture enthalpy, thermal and rheological properties, determination of heat and mass transfer characteristics, and cold storage through ice slurry

  2. Analysis of Three-Phase Thyristor Phase Control Circuit with Series RLC Elements

    OpenAIRE

    Himei, Toyoji; Nakanishi, Sen-ichiro; Funabiki, Shigeyuki; Komatsubara, Hitoshi; Kurose, Osamu

    1983-01-01

    An ac phase control circuit by thyristor is widely used in industry, The characteristics of the singlephase circuit with series RLC elements are numerically analyzed, and is reported the interesting phenomenon of step-up voltage without transformer. However, the performance of three phase phase control circuit with series RLC elements is not made clear. In this paper, the performance of three-phasecontrol circuit of a balanced and an unbalanced load with series RLC elements is described. The ...

  3. Gait phase varies over velocities.

    Science.gov (United States)

    Liu, Yancheng; Lu, Kun; Yan, Songhua; Sun, Ming; Lester, D Kevin; Zhang, Kuan

    2014-02-01

    We sought to characterize the percent (PT) of the phases of a gait cycle (GC) as velocity changes to establish norms for pathological gait characteristics with higher resolution technology. Ninety five healthy subjects (49 males and 46 females with age 34.9 ± 11.8 yrs, body weight 64.0 ± 11.7 kg and BMI 23.5 ± 3.6) were enrolled and walked comfortably on a 10-m walkway at self-selected slower, normal, and faster velocities. Walking was recorded with a high speed camera (250 frames per second) and the eight phases of a GC were determined by examination of individual frames for each subject. The correlation coefficients between the mean PT of the phases of the three velocities gaits and PT defined by previous publications were all greater than 0.99. The correlation coefficient between velocity and PT of gait phases is -0.83 for loading response (LR), -0.75 for mid stance (MSt), and -0.84 for pre-swing (PSw). While the PT of the phases of three velocities from this study are highly correlated with PT described by Dr. Jacquenlin Perry decades ago, actual PT of each phase varied amongst these individuals with the largest coefficient variation of 24.31% for IC with slower velocity. From slower to faster walk, the mean PT of MSt diminished from 35.30% to 25.33%. High resolution recording revealed ambiguity of some gait phase definitions, and these data may benefit GC characterization of normal and pathological gait in clinical practice. The study results indicate that one should consider individual variations and walking velocity when evaluating gaits of subjects using standard gait phase classification.

  4. PHASIM, an advanced phased array antenna software simulator

    NARCIS (Netherlands)

    Keizer, W.P.M.N.

    2000-01-01

    A sophisticated phased array simulator software package for the design and analysis of planar phased array antennas is presented. This package can accurately simulate the far-field characteristics of a large variety of planar phased array configurations in both the frequency and time domain. The sim

  5. Temperature Characteristics of BJMOSFET

    Institute of Scientific and Technical Information of China (English)

    ZENG Yun; YAN Min; YANG Hong-guan; GAO Yun

    2005-01-01

    The resolution expression for the temperature dependence of the current and threshold voltage is deduced as well as the analysis of temperature characteristics of BJMOSFET. Equivalent circuit of analysis and simulation has been established for the BJMOSFET temperature characteristics. By using the general circuit simulation software of PSpice9 and computer simulation, characteristic graphs of the BJMOSFET output characteristic, transient characteristic and amplitude-frequency characteristic with temperature variation are obtained. The results accorded very good with theoretical analysis and proved that BJMOSFET has better temperature characteristics than traditional MOSFET.

  6. Carcass and meat characteristics of crossbred steers submitted to different nutritional strategies at growing and finishing phases Características da carcaça e da carne de novilhos mestiços submetidos a diferentes estratégias nutricionais na recria e terminação

    Directory of Open Access Journals (Sweden)

    Pedro Leonardo de Paula Rezende

    2012-05-01

    Full Text Available This study was carried out to evaluate the effects of different nutritional strategies at growing and finishing phases on carcass and meat characteristics from 24 crossbred steers predominatly Holstein, slaughtered at 15 months of age and with 395.00kg of body weight. At the growing phase, the animals were maintained on Brachiaria brizantha pasture with two levels of supplementation in amounts equivalent to 0.5 or 1.0% of body weight. Subsequently, the animals were finished in feedlot with diets composed of 50 or 80% of concentrate. The high level of the concentrate at the finishing phase increased significantly (PObjetivou-se com este estudo avaliar os efeitos de diferentes estratégias nutricionais na recria e terminação sobre as características da carcaça e da carne de 24 bovinos mestiços com predominância Holandês, abatidos com 15 meses de idade e 395,00kg de peso vivo. Na fase de recria, os animais foram mantidos em pastagem de Brachiaria brizantha com dois níveis de suplementação energética em quantidade equivalente a 0,5 ou 1,0% do peso vivo. Posteriormente, os animais foram terminados em confinamento com dietas compostas por 50 ou 80% de concentrado. Constatou-se efeito significativo (P<0,05 do nível de concentrado na terminação sobre o rendimento de carcaça quente em favor do nível alto (50,16 vs 48,62%. O menor nível de suplementação na recria resultou em maior (P<0,05 percentual de gordura na carcaça (25,61 vs 23,39%, mas não influenciou os percentuais de músculos e ossos. O nível alto de suplementação na recria proporcionou carne mais macia, requerendo menor força de cisalhamento (4,72 vs 6,66kg cm-3 e de coloração vermelha mais clara (3,88 vs 2,89 pontos. O nível alimentar alto na recria mostrou-se mais atrativo por ter efeitos positivos sobre algumas características importantes da carcaça e da carne, notadamente a maciez.

  7. On the Identification of design Feature Characteristics

    DEFF Research Database (Denmark)

    Mortensen, Niels Henrik; Andreasen, Mogens Myrup

    1996-01-01

    to functionality and its production. Therefor a definition of features as relationships between product design characteristics and life system characteristics is proposed. The life phase systems are the systems which gradually realise the product life, e.g. the production system, the transport system......In this paper it is argued that the core of design features is design characteristics, i.e. the design attributes which define the design (the results from design work) and determine the behaviour. It is asserted that design involves work on entireties, e.g. shape detail, its contribution...

  8. Chaos dynamic characteristics during mine fires

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Mine fires break out and continue in confmed scopes, studying mine fire dynamics characteristics is very usefulto prevent and control fire. The judgement index of fire chaos characteristics was introduced, chaos analysis of mine Fireprocess was described, and the reconstruction of phase space was also presented. An example of mine fire was calculated.The computations show that it is feasible to analyze mine fire dynamic characteristics with chaos theory, and indicate thatfire preoeas is a catastrophe, that is to say, the fire system changes from one state to another during mine fire

  9. A wavelet phase filter for emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, E.T.; Lin, B. [Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Mathematics

    1995-07-01

    The presence of a high level of noise is a characteristic in some tomographic imaging techniques such as positron emission tomography (PET). Wavelet methods can smooth out noise while preserving significant features of images. Mallat et al. proposed a wavelet based denoising scheme exploiting wavelet modulus maxima, but the scheme is sensitive to noise. In this study, the authors explore the properties of wavelet phase, with a focus on reconstruction of emission tomography images. Specifically, they show that the wavelet phase of regular Poisson noise under a Haar-type wavelet transform converges in distribution to a random variable uniformly distributed on [0, 2{pi}). They then propose three wavelet-phase-based denoising schemes which exploit this property: edge tracking, local phase variance thresholding, and scale phase variation thresholding. Some numerical results are also presented. The numerical experiments indicate that wavelet phase techniques show promise for wavelet based denoising methods.

  10. Phase equilibrium engineering

    CERN Document Server

    Brignole, Esteban Alberto

    2013-01-01

    Traditionally, the teaching of phase equilibria emphasizes the relationships between the thermodynamic variables of each phase in equilibrium rather than its engineering applications. This book changes the focus from the use of thermodynamics relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. Phase Equilibrium Engineering presents a systematic study and application of phase equilibrium tools to the development of chemical processes. The thermodynamic modeling of mixtures for process development, synthesis, simulation, design and

  11. Numerical simulations of the phase separation properties for the thermal aged CDSS with Phase Field Model

    Energy Technology Data Exchange (ETDEWEB)

    Xue Fei [Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China); Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Wang Zhaoxi, E-mail: wangzx03@mails.tsinghua.edu.cn [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Applied Mechanics Laboratory, Tsinghua University, Beijing 100084 (China); Zhang Guodong [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009 (China); Qu Baoping; Shi Huiji [Applied Mechanics Laboratory, Tsinghua University, Beijing 100084 (China); Shu Guogang [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Liu Wei [Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2011-07-15

    Highlights: > Thermal aging causes the Cr-rich phase precipitate and form clusters. > Phase field dynamic model is used for simulating the phase separation coarsening. > Damage initiated more easily in the ferrite matrix for the Cr clusters. - Abstract: Experiments and numerical simulations with Phase Field Model and Finite Element Analysis were carried out to investigate the phase separation dynamic properties and the corresponding thermal aging degradation mechanism. Experimental results from transmission electron microscopy and atomic force microscopy show that thermal aging causes the Cr-rich phase precipitate and form clusters. A phase field dynamic model was developed with constitutive relations and empirical potential functions to investigate the phase separation dynamics in the ferrite phase. Numerical results integrated with cell dynamical system method show clearly the micro structure morphology and the phase separation coarsening with aging time. The evolution process of the phase separation was quantitatively illustrated and reproduced macroscopically. The scattering pattern becomes clearer and the corresponding radius becomes smaller along with the increasing aging time. The average characteristic length increases firstly then decreases and enters a more stable stage. With the increment of the local Cr concentration, the evolution of the phase morphology was quite different. Finite Element Analysis simulation results with the Gurson-Tvergaard-Needleman void model show that the damage initiated more easily in the ferrite matrix for the Cr atoms forming clusters with increasing aging time. The phenomenological simulations with Phase Field Model and Finite Element Analysis were in remarkably good agreement with experimental results and analytical considerations.

  12. Using phase II data for the analysis of phase III studies: An application in rare diseases.

    Science.gov (United States)

    Wandel, Simon; Neuenschwander, Beat; Röver, Christian; Friede, Tim

    2017-06-01

    Clinical research and drug development in orphan diseases are challenging, since large-scale randomized studies are difficult to conduct. Formally synthesizing the evidence is therefore of great value, yet this is rarely done in the drug-approval process. Phase III designs that make better use of phase II data can facilitate drug development in orphan diseases. A Bayesian meta-analytic approach is used to inform the phase III study with phase II data. It is particularly attractive, since uncertainty of between-trial heterogeneity can be dealt with probabilistically, which is critical if the number of studies is small. Furthermore, it allows quantifying and discounting the phase II data through the predictive distribution relevant for phase III. A phase III design is proposed which uses the phase II data and considers approval based on a phase III interim analysis. The design is illustrated with a non-inferiority case study from a Food and Drug Administration approval in herpetic keratitis (an orphan disease). Design operating characteristics are compared to those of a traditional design, which ignores the phase II data. An analysis of the phase II data reveals good but insufficient evidence for non-inferiority, highlighting the need for a phase III study. For the phase III study supported by phase II data, the interim analysis is based on half of the patients. For this design, the meta-analytic interim results are conclusive and would justify approval. In contrast, based on the phase III data only, interim results are inconclusive and require further evidence. To accelerate drug development for orphan diseases, innovative study designs and appropriate methodology are needed. Taking advantage of randomized phase II data when analyzing phase III studies looks promising because the evidence from phase II supports informed decision-making. The implementation of the Bayesian design is straightforward with public software such as R.

  13. Are streamflow recession characteristics really characteristic?

    Directory of Open Access Journals (Sweden)

    M. Stoelzle

    2012-09-01

    Full Text Available Streamflow recession has been investigated by a variety of methods, often involving the fit of a model to empirical recession plots to parameterize a non-linear storage-outflow relationship. Such recession analysis methods (RAMs are used to estimate hydraulic conductivity, storage capacity, or aquifer thickness and to model streamflow recession curves for regionalization and prediction at the catchment scale. Numerous RAMs have been published, but little is known about how characteristic the resulting recession models are to distinguish characteristic catchment behavior. In this study we combined three established recession extraction methods with three different parameter-fitting methods to the power-law storage-outflow model to compare the range of recession characteristics that result from the application of these different RAMs. Resulting recession characteristics including recession time and corresponding storage depletion were evaluated for 20 meso-scale catchments in Germany. We found plausible ranges for model parameterization, however, calculated recession characteristics varied over two orders of magnitude. While recession characteristics of the 20 catchments derived with the different methods correlate strongly, particularly for the RAMs that use the same extraction method and while they rank the catchments relatively consistent, there are still considerable differences among the methods. To elucidate this variability we discuss the ambiguous roles of recession extraction procedures and the parameterization of storage-outflow model and the limitations of the presented recession plots. The results suggest strong limitations to the comparability of recession characteristics derived with different methods, not only in the model parameters but also in the relative characterization of different catchments. A multiple methods approach to investigate streamflow recession characteristics should be considered for applications whenever possible.

  14. Three-Dimensional Icosahedral Phase Field Quasicrystal

    Science.gov (United States)

    Subramanian, P.; Archer, A. J.; Knobloch, E.; Rucklidge, A. M.

    2016-08-01

    We investigate the formation and stability of icosahedral quasicrystalline structures using a dynamic phase field crystal model. Nonlinear interactions between density waves at two length scales stabilize three-dimensional quasicrystals. We determine the phase diagram and parameter values required for the quasicrystal to be the global minimum free energy state. We demonstrate that traits that promote the formation of two-dimensional quasicrystals are extant in three dimensions, and highlight the characteristics required for three-dimensional soft matter quasicrystal formation.

  15. Phase Transitions in Two-Dimensional Traffic Flow Models

    CERN Document Server

    Cuesta, J A; Molera, J M; Cuesta, José A; Martinez, Froilán C; Molera, Juan M

    1993-01-01

    Abstract: We introduce two simple two-dimensional lattice models to study traffic flow in cities. We have found that a few basic elements give rise to the characteristic phase diagram of a first-order phase transition from a freely moving phase to a jammed state, with a critical point. The jammed phase presents new transitions corresponding to structural transformations of the jam. We discuss their relevance in the infinite size limit.

  16. Phase Transitions in Two-Dimensional Traffic Flow Models

    CERN Document Server

    Cuesta, José A; Molera, Juan M; Escuela, Angel Sánchez; 10.1103/PhysRevE.48.R4175

    2009-01-01

    We introduce two simple two-dimensional lattice models to study traffic flow in cities. We have found that a few basic elements give rise to the characteristic phase diagram of a first-order phase transition from a freely moving phase to a jammed state, with a critical point. The jammed phase presents new transitions corresponding to structural transformations of the jam. We discuss their relevance in the infinite size limit.

  17. Phase transition in Caenorhabditis elegans: A classical oil-water phase separation?

    Science.gov (United States)

    Weber, Christoph; Tony Hyman Collaboration; Andrés Delgadillo Collaboration; Frank Jülicher Team

    2014-03-01

    In Caenorhabditis elegans droplets form before the cell divides. These droplets, also referred to as P-granules, consist of a variety of unstructured proteins and mRNA. Brangwynne et al. [Science, 2009] showed that the P-granules exhibit fluid-like behavior and that the phase separation is controlled spatially by a gradient of a component called Mex-5. It is believed that this system exhibits the same characteristics as a classical oil-water phase separation. Here we report the recent experimental investigations on the phase separation in Caenorhabditis elegans and compare our findings with a classical oil-water phase separation. Specifically, we consider the underlying coarsening mechanisms as well as the impact of temperature and species composition. Finally, we present a preliminary model incorporating the characteristics of the phase separation kinetics for Caenorhabditis elegans.

  18. Phase diagram of crushed powders

    Science.gov (United States)

    Bodard, Sébastien; Jalbaud, Olivier; Saurel, Richard; Burtschell, Yves; Lapebie, Emmanuel

    2016-12-01

    Compression of monodisperse powder samples in quasistatic conditions is addressed in a pressure range such that particles fragmentation occurs while the solid remains incompressible (typical pressure range of 1-300 MPa for glass powders). For a granular bed made of particles of given size, the existence of three stages is observed during compression and crush up. First, classical compression occurs and the pressure of the granular bed increases along a characteristic curve as the volume decreases. Then, a critical pressure is reached for which fragmentation begins. During the fragmentation process, the granular pressure stays constant in a given volume range. At the end of this second stage, 20%-50% of initial grains are reduced to finer particles, depending on the initial size. Then the compression undergoes the third stage and the pressure increases along another characteristic curve, in the absence of extra fragmentation. The present paper analyses the analogies between the phase transition in liquid-vapour systems and powder compression with crush-up. Fragmentation diagram for a soda lime glass is determined by experimental means. The analogues of the saturation pressure and latent heat of phase change are determined. Two thermodynamic models are then examined to represent the crush-up diagram. The first one uses piecewise functions while the second one is of van der Waals type. Both equations of state relate granular pressure, solid volume fraction, and initial particle diameter. The piecewise functions approach provides reasonable representations of the phase diagram while the van der Waals one fails.

  19. Diffractive generalized phase contrast for adaptive phase imaging and optical security

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2012-01-01

    We analyze the properties of Generalized Phase Contrast (GPC) when the input phase modulation is implemented using diffractive gratings. In GPC applications for patterned illumination, the use of a dynamic diffractive optical element for encoding the GPC input phase allows for onthe- fly...... optimization of the input aperture parameters according to desired output characteristics. For wavefront sensing, the achieved aperture control opens a new degree of freedom for improving the accuracy of quantitative phase imaging. Diffractive GPC input modulation also fits well with grating-based optical...

  20. Multiple-phase behavior and memory effect of polymer gel

    CERN Document Server

    Annaka, M; Nakahira, T; Sugiyama, M; Hara, K; Matsuura, T

    2002-01-01

    A poly(4-acrylamidosalicylic acid) gel (PASA gel) exhibits multiple phases as characterized by distinct degrees of swelling; the gel can take one of four different swelling values, but none of the intermediate values. The gel has remarkable memory: the phase behavior of the gel depends on whether the gel has experienced the most swollen phase or the most collapsed phase in the immediate past. The information is stored and reversibly erased in the form of a macroscopic phase transition behavior. The structure factors corresponding to these four phases were obtained by SANS, which indicated the presence of characteristic structures depending on pH and temperature, particularly in the shrunken state. (orig.)

  1. Characteristic Classes and Integrable Systems

    CERN Document Server

    Levin, A; Smirnov, A; Zotov, A

    2010-01-01

    The classical Calogero-Moser (CM) system related to a simple Lie group $G$ can be described as the Hitchin system coming from a topologically trivial Higgs $G$-bundle. We consider topologically non-trivial Higgs bundles and construct corresponding integrable systems. We call them the modified Calogero-Moser systems (MCM systems). Their phase space has the same dimension as the phase space of the standard CM systems with spin, but have less number of particles but greater number of the spin variables. Topology of the underlying holomorphic bundles are defined by their characteristic classes. Such bundles occur if $G$ has a non-trivial center, i.e. classical simply-connected groups, $E_6$ and $E_7$. Starting with these bundles we construct new integrable systems, their Lax operators, quadratic Hamiltonians, define the phase spaces and the Poisson structure using dynamical r-matrices. To describe the systems we construct a special basis in the Lie algebras that generalizes the basis of t'Hooft matrices for sl(N)...

  2. Research on microcapsules of phase change materials

    Institute of Scientific and Technical Information of China (English)

    DAI Xia; SHEN Xiaodong

    2006-01-01

    Microcapsule technology is a kind of technology wrapping the solid or liquid into minute-sized particles within the field of micrometer or millimeter with film forming materials. This thesis introduces microcapsule technology of phase change materials and its main functions and the structural composition, preparation methods and characterization technology of microcapsule of phase change materials. The microcapsule of phase change materials is small in size and its temperature remains unchanged during the process of heat absorption and heat release. It is of great value in research and application prospect due to these characteristics.

  3. Propagation characteristics of seismic waves in shallow soil with the unsaturated three-phase p oro elastic mo del%用非饱和三相孔弹模型研究浅层土壤中地震波的传播特性

    Institute of Scientific and Technical Information of China (English)

    丁卫; 吴文雯; 王驰; 吴智强

    2014-01-01

    研究浅层土壤中声波耦合的地震波的传播特性,用于声波探雷技术的机理分析。根据浅层土壤具有孔隙度和可压缩性的特点,利用非饱和三相孔隙介质中的地震波模型,研究了土壤孔隙度、含水饱和度等参数对地震波传播特性的影响。计算结果显示:在给定的参数条件下,地震波的传播速度和衰减系数均随频率的增加而增加;纵波的传播速度随孔隙度的增加而减小,横波的传播速度随孔隙度的增加而增加;地震波的传播特性随含水饱和度的增加变化比较复杂。通过对计算结果与已发表实验结果的比较分析,讨论了解析方法的可行性,为声-地震耦合机理及其在声波探雷研究中的应用提供了一定的理论基础。%In order to study the mechanism of acoustic landmine detection, the propagation characteristics of acoustically coupled seismic waves in shallow soil are investigated. Based on the porosity and compressibility of shallow soil, the influences of parameters including soil porosity and water saturation on the propagation properties of seismic wave are discussed with the model of seismic waves in unsaturated three-phase porous medium. The calculation results show that under the given parameters, the propagation velocity and attenuation coefficient of seismic wave increase with the increase of acoustic frequency. The propagation velocities of longitudinal waves and those of transverse waves respectively decrease and increase with the increase of soil porosity. In addition, the propagation characteristics of acoustically coupled seismic waves become complicated with the increase of water saturation. The feasibility of the analysis method is discussed by comparing the calculation results with the experimental data published previously. As a result, a theoretical foundation is provided for the acoustic-to-seismic coupling mechanism and its application in the study of acoustic

  4. 激光区熔定向凝固Gd5Ge4合金的相选择与组织特征%Phase Selection and Microstructure Characteristics of Directionally Solidified GdsGe4 Alloy by Laser Zone Re-melting

    Institute of Scientific and Technical Information of China (English)

    张铁邦; 胡锐; 钟宏; 葛光男; 李金山

    2011-01-01

    The Gd5Ge4 alloy with the peritectic reaction during solidification was prepared by the arc-melt method under protection of argon atmosphere. The as-cast alloys were cut and directionally solidified with the help of laser rapid solidification technique. Microstructure characteristics and phase selection of Gd5Ge4 during the rapid directional solidification by laser zone re-melting were investigated. The microstructure originating from steady-state growth was evaluated with the help of optical microscope (OM) and X-ray diffraction (XRD). The alloy after laser zone directional solidification possesses obvious preferred orientation and the amorphization occurs under this condition. The cellular spacing could be expressed as a function of the laser scanning velocity during the rapid solidification. An acceptable combination is found between the experimental results and the classical J-H numerical solidification model for a rapid cellular/dendritic growth.%对具有包晶反应的Gd5Ge4金属间化合物进行激光区熔快速定向凝固实验,研究了Gd基磁致冷材料激光快速定向凝固过程中的相选择机制和显微组织特征.结果表明,激光区熔快速定向凝固后的Gd5Ge4合金具有明显的择优取向,合金在激光快凝条件下同时发生非晶化现象.GdsGe4合金定向凝固组织的片层间距随激光扫描速率的增加而减小,合金的凝固组织特征和激光扫描速率的关系符合J-H模型.

  5. Identification of characteristic flavor compounds in cocoa powder by gas chromatography-olfactometry-mass spectrometry with headspace solid phase micro-extraction%顶空固相微萃取结合GC-O与GC-MS技术鉴定可可粉中特征风味化合物

    Institute of Scientific and Technical Information of China (English)

    肖天鹏; 郑晓峰; 吕吉鸿; 郭泽峰; 高峰; 刘春凤; 李崎

    2012-01-01

    A method for headspace solid-phase microextraction(HS-SPME),followed by gas chromatography-olfactometry-mass spectrometry analysis was established for the identification of the characteristic flavor compounds in cocoa powder.According to the results,39 compounds which gave contribution to the flavor of cocoa powder were detected,including 7 aldehydes,3 alcohols,3 ketones,8 esters,2 acids,4 pyrazines,2 amines and any other special volatile substances.Among the flavor compounds,three compounds had key odorant(nutty,cocoa flavor),they were 2,5-dimethyl pyrazine,2,3,5-trimethyl pyrazine and 2,3,5,6-tetramethyl pyrazine.%利用顶空固相微萃取(HS-SPME)结合GC-O与GC-MS技术鉴定可可粉中的特征致香成分,鉴定出有39种化合物参与构成可可风味,分别是:7种醛、3种醇、3种酮、8种酯、2种酸、4种吡嗪、2种胺以及其他一些特殊的挥发性物质。其中具有典型可可风味(坚果,可可香)的关键化合物有3种,分别为2,5-二甲基吡嗪、2,3,5-三甲基吡嗪以及2,3,5,6-四甲基吡嗪。

  6. CrowdPhase: crowdsourcing the phase problem.

    Science.gov (United States)

    Jorda, Julien; Sawaya, Michael R; Yeates, Todd O

    2014-06-01

    The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as `crowdsourcing'. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of `individuals', each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it possible to extract meaningful information in cases where limited resolution might otherwise prevent initial phasing.

  7. Performance improvement of all digital phase-locked loop with adaptive multilevel-quantized phase comparator

    Science.gov (United States)

    Nakajima, Osamu; Hikawa, Hiroomi; Mori, Shinsaku

    1989-03-01

    A new type of phase comparator for DPLL (Digital Phase-Locked Loop), named Adaptive Multilevel-Quantized Phase Comparator (abbreviated as AMPC), is proposed. The characteristics of this proposed comparator AMPC are changed adaptively to reduce the frequency deviation and the phase jitter of the input signals, whereas the conventional phase comparator has constant characteristics whatever signals come. When the offset between input and output signal frequency exists, the amount of frequency control is increased by shifting up or down its chracteristics in order to decrease this deviation. When the loop is in the steady-state, the amount of phase control is decreased by varying the scale of them to suppress the input jitter. Performance characteristics of AMPC and the loop which uses AMPC are analyzed theoretically and verified by computer simulation. As a result, the loop which uses AMPC has much wider locking-range and much better jitter suppression effect than those of the conventional loops, and steady-state phase error is also reduced by using AMPC.

  8. Dynamic FLIR Target Acquisition. Phase I.

    Science.gov (United States)

    1978-08-02

    eas re: e r- tecr- ’t(, es will be ised for the Phase st Cy. 5.3.2 :ae Vnar -oles These v~r ies relate to the im.age characteristics which are...ground target detection and identification, TM 1-62, Aberdeen Proving Grounds, MD: Human Engineering Laboratories, Jan. 1962, (AD273696). Nygaand, J. E

  9. Characteristic Evolution and Matching

    Directory of Open Access Journals (Sweden)

    Winicour Jeffrey

    2005-12-01

    Full Text Available I review the development of numerical evolution codes for general relativity based upon the characteristic initial value problem. Progress is traced from the early stage of 1D feasibility studies to 2D axisymmetric codes that accurately simulate the oscillations and gravitational collapse of relativistic stars and to current 3D codes that provide pieces of a binary black hole spacetime. A prime application of characteristic evolution is to compute waveforms via Cauchy-characteristic matching, which is also reviewed.

  10. Propagating phase interface with intermediate interfacial phase: Phase field approach

    Science.gov (United States)

    Momeni, Kasra; Levitas, Valery I.

    2014-05-01

    An advanced three-phase phase field approach (PFA) is suggested for a nonequilibrium phase interface that contains an intermediate phase, in particular, a solid-solid interface with a nanometer-sized intermediate melt (IM). A thermodynamic potential in the polar order parameters is developed that satisfies all thermodynamic equilibrium and stability conditions. The special form of the gradient energy allowed us to include the interaction of two solid-melt interfaces via an intermediate melt and obtain a well-posed problem and mesh-independent solutions. It is proved that for stationary 1D solutions to two Ginzburg-Landau equations for three phases, the local energy at each point is equal to the gradient energy. Simulations are performed for β ↔δ phase transformations (PTs) via IM in an HMX energetic material. The obtained energy IM width dependence is described by generalized force-balance models for short- and long-range interaction forces between interfaces but not far from the melting temperature. A force-balance model is developed that describes phase field results even 100 K below the melting temperature. The effects of the ratios of width and energies of solid-solid and solid-melt interfaces, temperature, and the parameter characterizing interaction of two solid-melt interfaces, on the structure, width, energy of the IM and interface velocity are determined by finite element method. Depending on parameters, the IM may appear by continuous or discontinuous barrierless disordering or via critical nucleus due to thermal fluctuations. The IM may appear during heating and persist during cooling at temperatures well below than it follows from sharp-interface approach. On the other hand, for some parameters when IM is expected, it does not form, producing an IM-free gap. The developed PFA represents a quite general three-phase model and can be extended to other physical phenomena, such as martensitic PTs, surface-induced premelting and PTs, premelting

  11. High temperature phase equilibria and phase diagrams

    CERN Document Server

    Kuo, Chu-Kun; Yan, Dong-Sheng

    2013-01-01

    High temperature phase equilibria studies play an increasingly important role in materials science and engineering. It is especially significant in the research into the properties of the material and the ways in which they can be improved. This is achieved by observing equilibrium and by examining the phase relationships at high temperature. The study of high temperature phase diagrams of nonmetallic systems began in the early 1900s when silica and mineral systems containing silica were focussed upon. Since then technical ceramics emerged and more emphasis has been placed on high temperature

  12. Global periodic attractor of a class of third-order phase-locked loop

    Institute of Scientific and Technical Information of China (English)

    林源渠

    1997-01-01

    The uniform boundedness and existence of a global periodic attractor for a third-order phase-locked loop with general phase detector characteristics and frequency modulation input is proved under some parametric conditions.

  13. Engineering holographic phase diagrams

    Science.gov (United States)

    Chen, Jiunn-Wei; Dai, Shou-Huang; Maity, Debaprasad; Zhang, Yun-Long

    2016-10-01

    By introducing interacting scalar fields, we tried to engineer physically motivated holographic phase diagrams which may be interesting in the context of various known condensed matter systems. We introduce an additional scalar field in the bulk which provides a tunable parameter in the boundary theory. By exploiting the way the tuning parameter changes the effective masses of the bulk interacting scalar fields, desired phase diagrams can be engineered for the boundary order parameters dual to those scalar fields. We give a few examples of generating phase diagrams with phase boundaries which are strikingly similar to the known quantum phases at low temperature such as the superconducting phases. However, the important difference is that all the phases we have discussed are characterized by neutral order parameters. At the end, we discuss if there exists any emerging scaling symmetry associated with a quantum critical point hidden under the dome in this phase diagram.

  14. Therapy Provider Phase Information

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Therapy Provider Phase Information dataset is a tool for providers to search by their National Provider Identifier (NPI) number to determine their phase for...

  15. Digital quadrature phase detection

    Science.gov (United States)

    Smith, J.A.; Johnson, J.A.

    1992-05-26

    A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

  16. Interacting Weyl fermions: Phases, phase transitions, and global phase diagram

    Science.gov (United States)

    Roy, Bitan; Goswami, Pallab; Juričić, Vladimir

    2017-05-01

    We study the effects of short-range interactions on a generalized three-dimensional Weyl semimetal, where the band touching points act as the (anti)monopoles of Abelian Berry curvature of strength n . We show that any local interaction has a negative scaling dimension -2 /n . Consequently, all Weyl semimetals are stable against weak short-range interactions. For sufficiently strong interactions, we demonstrate that the Weyl semimetal either undergoes a first-order transition into a band insulator or a continuous transition into a symmetry breaking phase. A translational symmetry breaking axion insulator and a rotational symmetry breaking semimetal are two prominent candidates for the broken symmetry phase. At the one-loop order, the correlation length exponent for continuous transitions is ν =n /2 , indicating their non-Gaussian nature for any n >1 . We also discuss the scaling of the thermodynamic and transport quantities in general Weyl semimetals as well as inside broken symmetry phases.

  17. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation

  18. Phase jitter in a differential phase experiment.

    Science.gov (United States)

    Tanenbaum, B. S.; Connolly, D. J.; Austin, G. L.

    1973-01-01

    Austin (1971) had concluded that, because of the 'phase jitter,' the differential phase experiment is useful over a more limited height range than the differential absorption experiment. Several observations are presented to show that this conclusion is premature. It is pointed out that the logical basis of the differential absorption experiment also requires that the O- and X-mode echoes, at a given time, come from the same irregularities. Austin's calculations are believed to contain a systematic error above 80 km.

  19. Metastable phases and "metastable" phase diagrams

    OpenAIRE

    Brazhkin, V. V.

    2006-01-01

    The work discusses specifics of phase transitions for metastable states of substances. The objects of condensed media physics are primarily equilibrium states of substances with metastable phases viewed as an exception, while the overwhelming majority of organic substances investigated in chemistry are metastable. It turns out that at normal pressure many of simple molecular compounds based on light elements (these include: most hydrocarbons; nitrogen oxides, hydrates, and carbides; carbon ox...

  20. Recognizing frequency characteristics of gas sensor array

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel method based on independent component analyzing (ICA) in frequency domain to distinguish the frequency characteristics of multi-sensor system is presented. The conditions of this type of ICA are considered and each step of resolving the problem is discussed. For a two gas sensor array, the frequency characteristics including amplitude-frequency and phase-frequency are recognized by this method, and cross-sensitivity between them is also eliminated. From the principle of similarity, the recognition mean square error is no more than 0.085.

  1. Perceptions about Moon Phases.

    Science.gov (United States)

    Rider, Steven

    2002-01-01

    Presents research on different techniques to determine the level of understanding among middle school students regarding the phases of the moon. Quotes student responses to provide some insight into students' level of understanding of general knowledge about the moon, moon phases, and modeling the phases. Presents implications for teachers. (KHR)

  2. Characteristics of Successful Entrepreneurs.

    Science.gov (United States)

    McClelland, David C.

    1987-01-01

    Comparison of characteristics of 12 average and 12 superior small business people in three developing nations (India, Malawi, and Ecuador) found proactive qualities such as initiative and assertiveness, achievement orientation, and commitment to others characteristic of successful entrepreneurs. Other expected qualities (self-confidence,…

  3. Payment Instrument Characteristics

    DEFF Research Database (Denmark)

    Holst, Jacques; Kjeldsen, Martin; Hedman, Jonas

    2015-01-01

    payment innovations. Using the Repertory Grid technique to explore 15 payers’ perception of six payment instruments, including coins, banknotes, debit cards, credit cards, mobile payments, and on-line banking, we identify 16 payment characteristics. The characteristics aggregate seventy-six unique...

  4. Characteristics of Successful Entrepreneurs.

    Science.gov (United States)

    McClelland, David C.

    1987-01-01

    Comparison of characteristics of 12 average and 12 superior small business people in three developing nations (India, Malawi, and Ecuador) found proactive qualities such as initiative and assertiveness, achievement orientation, and commitment to others characteristic of successful entrepreneurs. Other expected qualities (self-confidence,…

  5. PhasePApy: A robust pure Python package for automatic identification of seismic phases

    Science.gov (United States)

    Chen, Chen; Holland, Austin

    2016-01-01

    We developed a Python phase identification package: the PhasePApy for earthquake data processing and near‐real‐time monitoring. The package takes advantage of the growing number of Python libraries including Obspy. All the data formats supported by Obspy can be supported within the PhasePApy. The PhasePApy has two subpackages: the PhasePicker and the Associator, aiming to identify phase arrival onsets and associate them to phase types, respectively. The PhasePicker and the Associator can work jointly or separately. Three autopickers are implemented in the PhasePicker subpackage: the frequency‐band picker, the Akaike information criteria function derivative picker, and the kurtosis picker. All three autopickers identify picks with the same processing methods but different characteristic functions. The PhasePicker triggers the pick with a dynamic threshold and can declare a pick with false‐pick filtering. Also, the PhasePicker identifies a pick polarity and uncertainty for further seismological analysis, such as focal mechanism determination. Two associators are included in the Associator subpackage: the 1D Associator and 3D Associator, which assign phase types to picks that can best fit potential earthquakes by minimizing root mean square (rms) residuals of the misfits in distance and time, respectively. The Associator processes multiple picks from all channels at a seismic station and aggregates them to increase computational efficiencies. Both associators use travel‐time look up tables to determine the best estimation of the earthquake location and evaluate the phase type for picks. The PhasePApy package has been used extensively for local and regional earthquakes and can work for active source experiments as well.

  6. Comparison of superresolution effects with annular phase and amplitude filters.

    Science.gov (United States)

    Luo, Hongxin; Zhou, Changhe

    2004-12-01

    The characteristics of annular amplitude and phase filters are compared. The behavior of two-zone phase and amplitude filters as the inner zone is increased is studied in detail. Numerical simulations show that a phase filter can achieve a superresolution effect, a circular Dammann effect, and flat-topped intensity for different applications, whereas a two-zone amplitude filter can generate only a superresolution effect. The experimental results show that both amplitude and phase filters can achieve superresolution. Generally, a phase superresolution filter is recommended for its higher efficiency and its special diffraction patterns that are impossible to achieve with an amplitude filter.

  7. Geometric phases in physics

    CERN Document Server

    Shapere, Alfred D

    1989-01-01

    During the last few years, considerable interest has been focused on the phase that waves accumulate when the equations governing the waves vary slowly. The recent flurry of activity was set off by a paper by Michael Berry, where it was found that the adiabatic evolution of energy eigenfunctions in quantum mechanics contains a phase of geometric origin (now known as 'Berry's phase') in addition to the usual dynamical phase derived from Schrödinger's equation. This observation, though basically elementary, seems to be quite profound. Phases with similar mathematical origins have been identified

  8. 基于啮合相位分析的盾构机减速器多级行星齿轮传动动力学特性%Dynamic Characteristics of Multi-stage Planetary Gears of Shield Tunnelling Machine Based on Planet Mesh Phasing Analysis

    Institute of Scientific and Technical Information of China (English)

    秦大同; 肖正明; 王建宏

    2011-01-01

    Based on gearing theory and Lagrange equation, the torsional dynamic model for multi-stages planetary gears train is developed by lumped-parameter method. Trapezoid waves are used to express the time-varying mesh stiffness, and the mesh phasing relations among planetary gears are analyzed. For the 3-stages planetary gears of shield tunnelling machine, the torsional vibration frequencies are calculated at the different mesh position of sun and planet gears. According to the characteristics of the gears mesh errors, the harmonic waves composited with shaft frequencies and mesh frequencies are presented to describe the transmission errors of die planetary gears. Considering the time-varying mesh stiffness with different mesh phases of planet gears, the inner excitations of 3-stages planetary gears are analyzed systematically. The dynamic responses of the 3-stages planetary gears are simulated under the inner and external excitation got from a statistical load, and the spectrum properties of gears vibration are also analyzed. The dynamic response of system components are calculated under different speeds for the reducer, and the relationship between gears vibration and the rotational speed of the reducer is studied, which provides the base for choosing the suitable operating condition of driving system of the shield tunnelling machine.%基于齿轮啮合理论和Lagrange方程,运用集中参数法建立多级行星齿轮系统的扭转动力学模型.采用梯形波表示啮合刚度的时变特性,分析行星齿轮啮合过程中的相位关系,计算盾构机减速器三级行星齿轮不同啮合位置的扭转振动结构频率.针对齿轮啮合误差特点,采用轴频和齿频叠加的谐波函数表示行星齿轮传动误差,考虑受啮合相位关系影响的行星齿轮系统时变刚度,系统分析多级行星齿轮传动的内部激励特征.基于某施工标段的统计负载,考虑内外激励,求解三级行星齿轮系统的动态响应,并对齿

  9. Effect of Phase Contiguity and Morphology on the Evolution of Deformation Texture in Two-Phase Alloys

    Science.gov (United States)

    Gurao, N. P.; Suwas, Satyam

    2017-02-01

    Deformation texture evolution in two-phase xFe- yNi-(100- x- y)Cr model alloys and Ti-13Nb-13Zr alloy was studied during rolling to develop an understanding of micro-mechanisms of deformation in industrially relevant two-phase FCC-BCC steels and HCP-BCC titanium alloys, respectively. It was found that volume fraction and contiguity of phases lead to systematic changes in texture, while morphology affects the strength of texture. There was a characteristic change in texture from typical Brass-type to a weaker Copper-type texture in the austenite phase accompanied with a change from alpha fiber to gamma fiber in ferrite phase for Fe-Ni-Cr alloys with increase in fraction of harder ferrite phase. However, similar characteristic texture evolution was noted in both α and β phase irrespective of the different initial morphologies in Ti-13Nb-13Zr alloy. Viscoplastic self-consistent simulations with two-phase scheme were able to qualitatively predict texture evolution in individual phases. It is proposed that the transition from iso-strain-type behavior for equiaxed microstructure at low strain to iso-stress-type behavior at higher strain is aided by the presence of higher volume fraction of the second phase and increasing aspect ratio of individual phases in two-phase alloys.

  10. Preparation of Nitrocellulose Gel Based on Phase Separation in Ternary System and Study on Its Dynamic Rheological Characteristics%三元体系相分离制备硝化纤维素凝胶及其动态流变性的研究

    Institute of Scientific and Technical Information of China (English)

    张云华; 邵自强

    2015-01-01

    The nitrocellulose (NC)gels were prepared from a ternary system NC/acetone/ethanol by solvent evapo-ration induced phase separation.The response degrees of the gel to external stimuli (such as strain,frequency,tem-perature)were investigated by linear rheological methods.Dynamic rheological characteristics of NC gels were stud-ied.Results show that the final morphologies of NC gels are influenced by mass ratios of the initial solvent/non-sol-vent (acetone/ethanol)and NC contents.The effect of changing initial acetone/ethanol ratios on the dynamic rheo-logical characteristics of the NC gels is different from the effect of changing NC contents.With increasing the ace-tone content,the volume of the NC gel prepared decreases,the NC content in the gel increases,the storage modulus (G′)and loss modulus (G″)of NC gels increase as well as the critical strain value (γc )decreases with increasing the NC content in the gels,whereas the value of G′and G″first increase and then decrease with increasing the NC con-tent in the gels when the mass ratio of acetone/ethanol is 2∶3.The values of G′and G″of all NC gels over the en-tire temperature scanning are basically unchanged,indicating that the interactions among NC chains and between NC/solvent can not be disrupted upon heating to higher temperatures.%通过溶剂蒸发引发相分离从硝化纤维素/丙酮/乙醇三元体系中制备出硝化纤维素凝胶,采用线性流变学方法考察凝胶对外界刺激(如应变、频率、温度)的响应程度,研究了凝胶的动态流变性能。结果表明,溶剂/非溶剂(丙酮/乙醇)质量比或硝化纤维素含量影响最终硝化纤维素凝胶的形貌,改变溶剂比例与硝化纤维素含量对硝化纤维素凝胶的动态流变性能的影响不同,增加丙酮含量,制备出的硝化纤维素凝胶体积减小,凝胶中硝化纤维素的含量增加,储能模量 G′和损耗模量 G″增加,临界应变(γc

  11. Topological phase effects

    CERN Document Server

    Robbins, J M

    2010-01-01

    Quantum eigenstates undergoing cyclic changes acquire a phase factor of geometric origin. This phase, known as the Berry phase, or the geometric phase, has found applications in a wide range of disciplines throughout physics, including atomic and molecular physics, condensed matter physics, optics, and classical dynamics. In this article, the basic theory of the geometric phase is presented along with a number of representative applications. The article begins with an account of the geometric phase for cyclic adiabatic evolutions. An elementary derivation is given along with a worked example for two-state systems. The implications of time-reversal are explained, as is the fundamental connection between the geometric phase and energy level degeneracies. We also discuss methods of experimental observation. A brief account is given of geometric magnetism; this is a Lorenz-like force of geometric origin which appears in the dynamics of slow systems coupled to fast ones. A number of theoretical developments of the...

  12. Generalized phase contrast:

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...... (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than...... efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, and can even enable a Reverse Phase Contrast mode where intensity patterns are converted into a phase modulation....

  13. Generalized Phase Contrast

    CERN Document Server

    Glückstad, Jesper

    2009-01-01

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, ...

  14. Generalized phase contrast:

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...... (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than...... the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light...

  15. Photometric Characteristics of Lunar Terrains

    Science.gov (United States)

    Sato, Hiroyuki; Hapke, Bruce W.; Denevi, Brett W.; Robinson, Mark

    2016-10-01

    The photometric properties of the lunar depend on albedo, surface roughness, porosity, and the internal/external structure of particles. Hapke parameter maps derived using a bidirectional reflectance model [Hapke, 2012] from Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images demonstrated the spatial and spectral variation of the photometric properties of the Moon [Sato et al., 2014]. Using the same methodology, here we present the photometric characteristics of typical lunar terrains, which were not systematically analyzed in the previous study.We selected five representative terrain types: mare, highland, swirls, and two Copernican (fresh) crater ejecta (one mare and one highlands example). As for the datasets, we used ~39 months of WAC repeated observations, and for each image pixel, we computed latitude, longitude, incidence, emission, and phase angles using the WAC GLD100 stereo DTM [Scholten et al., 2012]. To obtain similar phase and incidence angle ranges, all sampling sites are near the equator and in the vicinity of Reiner Gamma. Three free Hapke parameters (single scattering albedo: w, HG2 phase function parameter: c, and angular width of SHOE: hs) were then calculated for the seven bands (321-689 nm). The remaining parameters were fixed by simplifying the model [Sato et al., 2014].The highlands, highland ejecta, and swirl (Reiner Gamma) showed clearly higher w than the mare and mare ejecta. The derived c values were lower (less backscattering) for the swirl and higher (more backscattering) for the highlands (and ejecta) relative to the other sites. Forward scattering materials such as unconsolidated transparent crystalline materials might be relatively enriched in the swirl. In the highlands, anorthositic agglutinates with dense internal scattering could be responsible for the strong backscattering. The mare and mare ejecta showed continuously decreasing c from UV to visible wavelengths. This might be caused by the FeO-rich pyroxene

  16. Characteristic Evolution and Matching

    Directory of Open Access Journals (Sweden)

    Jeffrey Winicour

    2012-01-01

    Full Text Available I review the development of numerical evolution codes for general relativity based upon the characteristic initial-value problem. Progress in characteristic evolution is traced from the early stage of 1D feasibility studies to 2D-axisymmetric codes that accurately simulate the oscillations and gravitational collapse of relativistic stars and to current 3D codes that provide pieces of a binary black-hole spacetime. Cauchy codes have now been successful at simulating all aspects of the binary black-hole problem inside an artificially constructed outer boundary. A prime application of characteristic evolution is to extend such simulations to null infinity where the waveform from the binary inspiral and merger can be unambiguously computed. This has now been accomplished by Cauchy-characteristic extraction, where data for the characteristic evolution is supplied by Cauchy data on an extraction worldtube inside the artificial outer boundary. The ultimate application of characteristic evolution is to eliminate the role of this outer boundary by constructing a global solution via Cauchy-characteristic matching. Progress in this direction is discussed.

  17. Phase-Center Extension for a Microwave Feed Horn

    Science.gov (United States)

    Hartop, R. W.; Manshadi, F.

    1987-01-01

    Corrugated cylindrical tube relocates phase center of Cassegrain antenna feed. Proposed modification increases aperture of Cassegrain antenna from 64 to 70 m. Relatively inexpensive extension moves phase center of feed without incurring cost of redesigning horn and relocating low-noise equipment. Extension does not affect polarization characteristics of feed.

  18. Ka-Band Phased Array System Characterization

    Science.gov (United States)

    Acosta, R.; Johnson, S.; Sands, O.; Lambert, K.

    2001-01-01

    Phased Array Antennas (PAAs) using patch-radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector-based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA-based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2 pi phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased-array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link.

  19. [Radiotherapy phase I trials' methodology: Features].

    Science.gov (United States)

    Rivoirard, R; Vallard, A; Langrand-Escure, J; Guy, J-B; Ben Mrad, M; Yaoxiong, X; Diao, P; Méry, B; Pigne, G; Rancoule, C; Magné, N

    2016-12-01

    In clinical research, biostatistical methods allow the rigorous analysis of data collection and should be defined from the trial design to obtain the appropriate experimental approach. Thus, if the main purpose of phase I is to determine the dose to use during phase II, methodology should be finely adjusted to experimental treatment(s). Today, the methodology for chemotherapy and targeted therapy is well known. For radiotherapy and chemoradiotherapy phase I trials, the primary endpoint must reflect both effectiveness and potential treatment toxicities. Methodology should probably be complex to limit failures in the following phases. However, there are very few data about methodology design in the literature. The present study focuses on these particular trials and their characteristics. It should help to raise existing methodological patterns shortcomings in order to propose new and better-suited designs. Copyright © 2016 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  20. Phase-space quantization of field theory.

    Energy Technology Data Exchange (ETDEWEB)

    Curtright, T.; Zachos, C.

    1999-04-20

    In this lecture, a limited introduction of gauge invariance in phase-space is provided, predicated on canonical transformations in quantum phase-space. Exact characteristic trajectories are also specified for the time-propagating Wigner phase-space distribution function: they are especially simple--indeed, classical--for the quantized simple harmonic oscillator. This serves as the underpinning of the field theoretic Wigner functional formulation introduced. Scalar field theory is thus reformulated in terms of distributions in field phase-space. This is a pedagogical selection from work published and reported at the Yukawa Institute Workshop ''Gauge Theory and Integrable Models'', 26-29 January, 1999.

  1. Modeling phase noise in multifunction subassemblies.

    Science.gov (United States)

    Driscoll, Michael

    2012-03-01

    Obtaining requisite phase noise performance in hardware containing multifunction circuitry requires accurate modeling of the phase noise characteristics of each signal path component, including both absolute (oscillator) and residual (non-oscillator) circuit contributors. This includes prediction of both static and vibration-induced phase noise. The model (usually in spreadsheet form) is refined as critical components are received and evaluated. Additive (KTBF) phase noise data can be reasonably estimated, based on device drive level and noise figure. However, accurate determination of component near-carrier (multiplicative) and vibration-induced noise usually must be determined via measurement. The model should also include the effects of noise introduced by IC voltage regulators and properly discriminate between common versus independent signal path residual noise contributors. The modeling can be easily implemented using a spreadsheet.

  2. Payment Instrument Characteristics

    DEFF Research Database (Denmark)

    Holst, Jacques; Kjeldsen, Martin; Hedman, Jonas;

    2015-01-01

    Over the last decade, we have witnessed payment innovations that fundamentally have changed the ways we pay. Payment innovations, such as mobile payments and on-line banking, include characteristics or features that are essential to understand if we want to know how and why payers choose among...... payment innovations. Using the Repertory Grid technique to explore 15 payers’ perception of six payment instruments, including coins, banknotes, debit cards, credit cards, mobile payments, and on-line banking, we identify 16 payment characteristics. The characteristics aggregate seventy-six unique...

  3. Nonsupplemented luteal phase characteristics after the administration of recombinant human chorionic gonadotropin, recombinant luteinizing hormone, or gonadotropin-releasing hormone (GnRH) agonist to induce final oocyte maturation in in vitro fertilization patients after ovarian stimulation with recombinant follicle-stimulating hormone and GnRH antagonist cotreatment

    NARCIS (Netherlands)

    N.S. Macklon (Nick); M.J.C. Eijkemans (René); M. Ludwig (Michael); R.E. Felberbaum; K. Diedrich; S. Bustion; E. Loumaye; B.C.J.M. Fauser (Bart); N.G.M. Beckers (Nicole)

    2003-01-01

    textabstractReplacing GnRH agonist cotreatment for the prevention of a premature rise in LH during ovarian stimulation for in vitro fertilization (IVF) by the late follicular phase administration of GnRH antagonist may render supplementation of the luteal phase redundant, because o

  4. Coherent-Phase Monitoring Of Cavitation In Turbomachines

    Science.gov (United States)

    Jong, Jen-Yi

    1996-01-01

    Digital electronic signal-processing system analyzes outputs of accelerometers mounted on turbomachine to detect vibrations characteristic of cavitation. Designed to overcome limitation imposed by interference from discrete components. System digitally implements technique called "coherent-phase wide-band demodulation" (CPWBD), using phase-only (PO) filtering along envelope detection to search for unique coherent-phase relationship associated with cavitation and to minimize influence of large-amplitude discrete components.

  5. Phase noise of self-sustained optomechanical oscillators

    OpenAIRE

    Fong, King Yan; Poot, Menno; Han, Xu; Tang, Hong X.

    2014-01-01

    In this paper we present a theory that predicts the phase noise characteristics of self-sustained optomechanical oscillators. By treating the cavity optomechanical system as a feedback loop consisting of an optical cavity and a mechanical resonator, we analytically derive the transfer functions relating the amplitude/phase noise of all the relevant dynamical quantities from the quantum Langevin equations, and obtain a closed-form expressions for the phase noise spectral densities contributed ...

  6. Modeling Pulse Characteristics in Xenon with NEST

    CERN Document Server

    Mock, Jeremy; Kazkaz, Kareem; Szydagis, Matthew; Tripathi, Mani; Uvarov, Sergey; Woods, Michael; Walsh, Nicholas

    2013-01-01

    A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, effects such as the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, parameters such as ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

  7. Resident Characteristics Report

    Data.gov (United States)

    Department of Housing and Urban Development — The Resident Characteristics Report summarizes general information about households who reside in Public Housing, or who receive Section 8 assistance. The report...

  8. Experimental study on the characteristics of semiconductor opening switch

    CERN Document Server

    Su Jian Cang; Ding Yong Zhong; Song Zhi Min; Ding Zhen Jie; Liu Guo Zhi

    2002-01-01

    An experimental set-up is developed to measure the characteristics of semiconductor opening switch (SOS). The parameters, such as interruption impedance, current int eruption time, voltage gain, pulse duration and energy transfer efficiency, are studied experimentally. The experimental results show that forward pumping time and reverse pumping time are important parameters for semiconductor opening switches. The influences of forward pumping time and reverse pumping time on interruption time, voltage gain, and energy transfer efficiency are obtained. In the interruption process, the impedance variation is divided into three phases: that is rapid increasing phase, slow change phase and completely interruption phase

  9. Interacting Weyl fermions: Phases, phase transitions and global phase diagram

    CERN Document Server

    Roy, Bitan; Juricic, Vladimir

    2016-01-01

    We study the effects of short-range interactions on a generalized three-dimensional Weyl semimetal, where the band touching points act as the (anti)monopoles of Abelian Berry curvature of strength $n$. We show that any local interaction has a \\emph{negative} scaling dimension $-2/n$. Consequently all Weyl semimetals are stable against weak short-range interactions. For sufficiently strong interactions, we demonstrate that the Weyl semimetal either undergoes a first order transition into a band insulator or a continuous transition into a symmetry breaking phase. A translational symmetry breaking axion insulator and a rotational symmetry breaking semimetal are two prominent candidates for the broken symmetry phase. At one loop level, the correlation length exponent for continuous transitions is $\

  10. In-phase and anti-phase synchronization in noisy Hodgkin-Huxley neurons.

    Science.gov (United States)

    Ao, Xue; Hänggi, Peter; Schmid, Gerhard

    2013-09-01

    We numerically investigate the influence of intrinsic channel noise on the dynamical response of delay-coupling in neuronal systems. The stochastic dynamics of the spiking is modeled within a stochastic modification of the standard Hodgkin-Huxley model wherein the delay-coupling accounts for the finite propagation time of an action potential along the neuronal axon. We quantify this delay-coupling of the Pyragas-type in terms of the difference between corresponding presynaptic and postsynaptic membrane potentials. For an elementary neuronal network consisting of two coupled neurons we detect characteristic stochastic synchronization patterns which exhibit multiple phase-flip bifurcations: The phase-flip bifurcations occur in form of alternate transitions from an in-phase spiking activity towards an anti-phase spiking activity. Interestingly, these phase-flips remain robust for strong channel noise and in turn cause a striking stabilization of the spiking frequency.

  11. A Characteristic Particle Length

    CERN Document Server

    Roberts, Mark D

    2015-01-01

    It is argued that there are characteristic intervals associated with any particle that can be derived without reference to the speed of light $c$. Such intervals are inferred from zeros of wavefunctions which are solutions to the Schr\\"odinger equation. The characteristic length is $\\ell=\\beta^2\\hbar^2/(8Gm^3)$, where $\\beta=3.8\\dots$; this length might lead to observational effects on objects the size of a virus.

  12. Housing characteristics 1993

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    This report, Housing Characteristics 1993, presents statistics about the energy-related characteristics of US households. These data were collected in the 1993 Residential Energy Consumption Survey (RECS) -- the ninth in a series of nationwide energy consumption surveys conducted since 1978 by the Energy Information Administration of the US Department of Energy. Over 7 thousand households were surveyed, representing 97 million households nationwide. A second report, to be released in late 1995, will present statistics on residential energy consumption and expenditures.

  13. Database on Wind Characteristics

    DEFF Research Database (Denmark)

    Højstrup, J.; Ejsing Jørgensen, Hans; Lundtang Petersen, Erik

    1999-01-01

    his report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061......his report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061...

  14. Database on Wind Characteristics

    DEFF Research Database (Denmark)

    Højstrup, J.; Ejsing Jørgensen, Hans; Lundtang Petersen, Erik

    1999-01-01

    his report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061......his report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061...

  15. Contemporary research of dynamically induced phase transitions

    Science.gov (United States)

    Hull, L. M.

    2017-01-01

    Dynamically induced phase transitions in metals, within the present discussion, are those that take place within a time scale characteristic of the shock waves and any reflections or rarefactions involved in the loading structure along with associated plastic flow. Contemporary topics of interest include the influence of loading wave shape, the effect of shear produced by directionality of the loading relative to the sample dimensions and initial velocity field, and the loading duration (kinetic effects, hysteresis) on the appearance and longevity of a transformed phase. These topics often arise while considering the loading of parts of various shapes with high explosives, are typically two or three-dimensional, and are often selected because of the potential of the transformed phase to significantly modify the motion. In this paper, we look at current work on phase transitions in metals influenced by shear reported in the literature, and relate recent work conducted at Los Alamos on iron's epsilon phase transition that indicates a significant response to shear produced by reflected elastic waves. A brief discussion of criteria for the occurrence of stress induced phase transitions is provided. Closing remarks regard certain physical processes, such as fragmentation and jet formation, which may be strongly influenced by phase transitions.

  16. Phase Transition Analysis Based Quality Prediction for Multi-phase Batch Processes

    Institute of Scientific and Technical Information of China (English)

    赵露平; 赵春晖; 高福荣

    2012-01-01

    Batch processes are usually involved with multiple phases in the time domain and many researches on process monitoring as well as quality prediction have been done using phase information. However, few of them consider phase transitions, though they exit widely in batch processes and have non-ignorable impacts on product qualities. In the present work, a phase-based partial least squares (PLS) method utilizing transition information is proposed to give both online and offline quality predictions. First, batch processes are divided into several phases using regression parameters other than prior process knowledge. Then both steady phases and transitions which have great influences on qualities are identified as critical-to-quality phases using statistical methods. Finally, based on the analysis of different characteristics of transitions and steady phases, an integrated algorithm is developed for quality prediction. The application to an injection molding process shows the effectiveness of the proposed algorithm in comparison with the traditional MPLS method and the phase-based PLS method.

  17. Gymnastics in Phase Space

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alexander Wu; /SLAC

    2012-03-01

    As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.

  18. Fractal characteristics for binary noise radar waveform

    Science.gov (United States)

    Li, Bing C.

    2016-05-01

    Noise radars have many advantages over conventional radars and receive great attentions recently. The performance of a noise radar is determined by its waveforms. Investigating characteristics of noise radar waveforms has significant value for evaluating noise radar performance. In this paper, we use binomial distribution theory to analyze general characteristics of binary phase coded (BPC) noise waveforms. Focusing on aperiodic autocorrelation function, we demonstrate that the probability distributions of sidelobes for a BPC noise waveform depend on the distances of these sidelobes to the mainlobe. The closer a sidelobe to the mainlobe, the higher the probability for this sidelobe to be a maximum sidelobe. We also develop Monte Carlo framework to explore the characteristics that are difficult to investigate analytically. Through Monte Carlo experiments, we reveal the Fractal relationship between the code length and the maximum sidelobe value for BPC waveforms, and propose using fractal dimension to measure noise waveform performance.

  19. Phase Equilibria Diagrams Database

    Science.gov (United States)

    SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

  20. Dual phase evolution

    CERN Document Server

    Green, David G; Abbass, Hussein A

    2014-01-01

    This book explains how dual phase evolution operates in all these settings and provides a detailed treatment of the subject. The authors discuss the theoretical foundations for the theory, how it relates to other phase transition phenomena and its advantages in evolutionary computation and complex adaptive systems. The book provides methods and techniques to use this concept for problem solving. Dual phase evolution concerns systems that evolve via repeated phase shifts in the connectivity of their elements. It occurs in vast range of settings, including natural systems (species evolution, landscape ecology, geomorphology), socio-economic systems (social networks) and in artificial systems (annealing, evolutionary computing).

  1. Modeling of liquid phases

    CERN Document Server

    Soustelle, Michel

    2015-01-01

    This book is part of a set of books which offers advanced students successive characterization tool phases, the study of all types of phase (liquid, gas and solid, pure or multi-component), process engineering, chemical and electrochemical equilibria, and the properties of surfaces and phases of small sizes. Macroscopic and microscopic models are in turn covered with a constant correlation between the two scales. Particular attention has been given to the rigor of mathematical developments. This second volume in the set is devoted to the study of liquid phases.

  2. Solid phase transformations II

    CERN Document Server

    Čermák, J

    2009-01-01

    This topical volume includes ten invited papers that cover selected areas of the field of solid phase transformations. The first two contributions represent a burgeoning branch; that of the computer simulation of physical phenomena. The following three articles deal with the thermodynamics of phase transformations as a basic theory for describing the phenomenology of phase changes in matter. The next paper describes the interconnections between structural stability and the electronic structure of phases. Two further articles are devoted to displacive transformations; a field where there are ma

  3. THE PHASE-OFFSET OVERLAPPED WAVE TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Liang Dequn; Liang Weihua; Sun Changnian

    2003-01-01

    A new digital communication technology based on the Phase-Offset Overlapped Waves (POOW) has been introduced in this letter. The waves can be considered as a special multicarrier different from traditional ones. The sub-waves in a coded word's period of the POOW are sine waves and have the same frequencies, but different starting phases. The most important characteristic is that these sub-waves are the piecewise functions and not orthogonal in a code word period. The decoding can be implemented by solving a linear equation group.This code has very high efficiency and thus the data transmission rate is increased greatly.

  4. Transient two-phase performance of LOFT reactor coolant pumps

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T.H.; Modro, S.M.

    1983-01-01

    Performance characteristics of Loss-of-Fluid Test (LOFT) reactor coolant pumps under transient two-phase flow conditions were obtained based on the analysis of two large and small break loss-of-coolant experiments conducted at the LOFT facility. Emphasis is placed on the evaluation of the transient two-phase flow effects on the LOFT reactor coolant pump performance during the first quadrant operation. The measured pump characteristics are presented as functions of pump void fraction which was determined based on the measured density. The calculated pump characteristics such as pump head, torque (or hydraulic torque), and efficiency are also determined as functions of pump void fractions. The importance of accurate modeling of the reactor coolant pump performance under two-phase conditions is addressed. The analytical pump model, currently used in most reactor analysis codes to predict transient two-phase pump behavior, is assessed.

  5. UPVG phase 2 report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-08-01

    The Utility PhotoVoltaic Group (UPVG), supported by member dues and a grant from the US Department of Energy, has as its mission the acceleration of the use of cost-effective small-scale and emerging large-scale applications of photovoltaics for the benefit of electric utilities and their customers. Formed in October, 1992, with the support of the American Public Power Association, Edison Electric Institute, and the National Rural Electric Cooperative Association, the UPVG currently has 90 members from all sectors of the electric utility industry. The UPVG`s efforts as conceived were divided into four phases: Phase 0--program plan; Phase 1--organization and strategy development; Phase 2--creating market assurance; and Phase 3--higher volume purchases. The Phase 0 effort developed the program plan and was completed early in 1993. The Phase 1 goal was to develop the necessary background information and analysis to lead to a decision as to which strategies could be undertaken by utilities to promote greater understanding of PV markets and achieve increased volumes of PV purchases. This report provides the details of the UPVG`s Phase 2 efforts to initiate TEAM-UP, its multiyear, 50-MW hardware initiative.

  6. LIGHT NONAQUEOUS PHASE LIQUIDS

    Science.gov (United States)

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  7. Lunar Phases Planisphere

    Science.gov (United States)

    Shawl, Stephen J.

    2010-01-01

    This paper describes a lunar phases planisphere with which a user can answer questions about the rising and setting times of the Moon as well as questions about where the Moon will be at a given phase and time. The article contains figures that can be photocopied to make the planisphere. (Contains 2 figures.)

  8. Dynamic Characteristics of Multi-stage Planetary Gears of Shield Tunnelling Machine Based on Planet Mesh Phasing Analysis%面向寿命终结阶段的机械产品设计绿色多准则优化

    Institute of Scientific and Technical Information of China (English)

    高一聪; 冯毅雄; 谭建荣; 施健

    2011-01-01

    characteristics of EOL processing. Based on the mathematical model of product optimization design for EOL processing, the Pareto set for the multi-objective optimization problem is obtained using the multi-objective optimization algorithm. The multi-objective Pareto-optimal solutions are facilitating operations of the EOL phase. The efficiency and effectiveness of the proposed method is illustrated by the green multi-criteria optimization for product design project of gearless traction machine.

  9. A Study of Characteristic of Short-Circuit Current Contributed by DC Systems With Single-Phase Short-Circuit Fault on AC Side%交流侧单相短路时直流系统提供短路电流的特性分析

    Institute of Scientific and Technical Information of China (English)

    王铁柱; 万磊; 张彦涛; 卜广全

    2016-01-01

    随着直流输电系统的迅速发展,能否忽略直流系统对短路电流的贡献成为一个亟待研究的问题。文章基于实际直流工程的详细电磁暂态模型,对交流侧发生单相短路故障时直流系统提供短路电流的特性进行研究。通过分析故障后直流输电系统的暂态特性,提出针对短路电流计算关键值,提取并分析直流系统提供短路电流的对应分量;通过对大量仿真结果的统计分析,明确了直流系统提供短路电流的特性及其对短路电流计算的影响,得出结论:直流系统提供的短路电流会使短路电流计算中的工频短路电流初始值、对称开断短路电流的幅值减小,而短路电流峰值增大,且工程应用中短路电流计算可以不考虑直流系统。通过基于实际电网的短路电流对比计算,验证了以上结论。%With rapid development of HVDC systems, it has become important to determine whether DC system contribution can be ignored in short-circuit (SC) current calculation. This paper studies characteristic of SC current contributed by DC systems with single-phase SC fault on AC Side, based on a detailed electromagnetic transient model. By analyzing transient process of a DC system during fault, it is proposed that certain components of SC current contributed by DC systems should be extracted and analyzed, corresponding to critical value of SC current calculation. Based on statistical analysis of a large number of simulation results, features of SC current contributed by DC systems are proposed, as well as its impact on SC current calculation. It is concluded that, SC current contributed by DC systems will decrease amplitude of initial symmetrical SC current and symmetrical breaking SC current, but will increase SC peak current, and that for engineering applications, DC system can be ignored in SC current calculation. Comparative calculation of SC current based on actual grid verifies above

  10. Research on phase characteristic of acupuncture on circadian rhythm disturbance due to advanced light/dark cycle%针刺调整超前性光暗周期转移后节律紊乱的时相特征研究

    Institute of Scientific and Technical Information of China (English)

    蔡定均; 魏焦禄; 赵纪岚; 谢川; 刘旭光; 朱丽; 周奇志

    2011-01-01

    Objective: Research on the phase characteristic of acupuncture on the circadian rhythm disturbance produced by 10 days of serial 8-hour advances of light/dark cycle every 2 days. Methods: Syrian hamsters were synchronized to lighting conditions of LD14:10, and then, circadian rhythm disturbance models were produced by 10 days of serial 8-hour advances of light/dark cycle every 2 days. Comparing the effect of acupuncturing 'Balhui(DU20)' and 'Changqiang(DU1)' points after advanced light/dark cycle at different time. Results: After advanced light/dark cycle, the spontaneous behavior of golden hamsters shifted forward. Their average shift extent of different hatches and different groups was from 156.14 to 586.00 min. When acupunctured at ZT16 and ZT0, the time of resynchronization was less than the natural recovery group, but they weren't different in statistics. Compared with other groups, the outstanding effective of promoting circadian rhythm resynchronization was observed in acupuncture group at ZT4, ZT8 and ZT12. While at ZT20 the time of resynchronization in the treated group was longer than that in the natural recovery group, but they weren't different in statistics. Conclusion: Firsfiy, acupuncture could promote circadian rhythm resynchronization. Secondly, the effective of acupuncture on resynchronization was circadian-dependent effects.%目的:揭示针刺调整金黄地鼠超前性光暗周期转移后节律紊乱的时相特征.方法:采用超前性光暗周期转移方法模拟慢性轮班工作复制昼夜节律紊乱模型,观察不同时间点电针"百会"、"长强"对金黄地鼠超前性光暗周期相位转移后节律再同步的影响.结果:在模拟超前性光暗周期转移后,金黄地鼠的活动均向前漂移.不同批次不同组动物的平均漂移幅度在156.14-586.00min之间.在ZT16(24:00)、ZT0(8:00)针刺,与自然恢复组比较,针刺组再同步所用天数虽小于自然恢复组,但是两者之间无统计学差异;在ZT4

  11. Impact of Perception of Teachers’ Supporting, Stress, Coping Style and Demographic Characteristics on Professional Identity of Nursing Students in Later Phase of Clinical Practice%实习后期护生感知的教师支持应激水平应对方式及人口学特征对职业认同感的影响

    Institute of Scientific and Technical Information of China (English)

    冀鹏飞; 李娟; 周兰姝

    2013-01-01

    Objective To understand status quo of professional identity of nursing students in the later phase of clinical practice, to analyze the impact of the perception of the teachers’ supporting, stress, coping style and demographic characteristics on students’ professional identity. Methods Totally 282 nursing students in Shanghai were investigated eight months after clinical practice. Results The total score of professional identity of nursing students was 37.78±6.53. Multiple stepwise regression analysis showed that the perception of the teachers’ supporting, educational background, coping style and stress had influence on professional identity (P<0.01). There was positive relationship among the perception of the teachers’ supporting, optimistic coping style and professional identity (P<0.01) and negative relationship between stress and professional identity (P<0.01). There was lower professional identity in nursing undergraduates (P<0.01). Conclusion Professional identity of nursing students maintains in a mediate or above level. Teachers’ support, optimistic coping style, and alleviation of stress could contribute to building better professional identity.%  目的了解护生临床实习后期职业认同感现状,并分析一般人口学资料、护生感知的教师支持、应激水平及应对方式对职业认同感的影响.方法采用问卷调查法,对在上海市长海医院、长征医院实习的282名2012届护生在实习后期进行调查.结果护生职业认同感总分为(37.78±6.53)分,处于中等偏上水平.多元逐步回归显示,教师支持、学历、乐观应对、应激水平对护生职业认同感有影响;其中教师支持、乐观应对与护生职业认同感呈正相关(P<0.01),应激水平与护生职业认同感呈负相关(P<0.01),本科生比大专生职业认同感低(P<0.01).结论护生职业认同感处于中等偏上水平,教师应该加强对其的支持、理解,尤其是本科护生

  12. Phenomenal characteristics of cryptomnesia.

    Science.gov (United States)

    Brédart, Serge; Lampinen, James M; Defeldre, Anne-Catherine

    2003-01-01

    Qualitative characteristics of cryptomnesia, or unintentional plagiarism were investigated. In Experiment 1 we compared accurate and inaccurate source attributions in terms of their level of confidence using instructions that did not require a fixed number of responses. Confidence was lower for plagiarised responses than for correct responses. Nevertheless, participants provided high ratings of certainty for a large proportion of their plagiarised responses. In Experiment 2 the phenomenological differences between plagiarised recall and veridical recall were compared by using an adaptation of the memory characteristics questionnaire (Johnson, Foley, Suengas, & Raye, 1988). Correct responses were associated with more experiential detail than plagiarised responses. However, a considerable number of plagiarised responses were accompanied by a confident memory of at least one qualitative characteristic. Results are discussed in terms of the source monitoring framework developed by Johnson, Hashtroudi, and Lindsay (1993).

  13. Characteristic Evolution and Matching

    Directory of Open Access Journals (Sweden)

    Winicour Jeffrey

    2009-04-01

    Full Text Available I review the development of numerical evolution codes for general relativity based upon the characteristic initial value problem. Progress is traced from the early stage of 1D feasibility studies to 2D axisymmetric codes that accurately simulate the oscillations and gravitational collapse of relativistic stars and to current 3D codes that provide pieces of a binary black hole spacetime. Cauchy codes have now been successful at simulating all aspects of the binary black hole problem inside an artificially constructed outer boundary. A prime application of characteristic evolution is to eliminate the role of this artificial outer boundary via Cauchy-characteristic matching, by which the radiated waveform can be computed at null infinity. Progress in this direction is discussed.

  14. Commercial Buildings Characteristics, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1994-04-29

    Commercial Buildings Characteristics 1992 presents statistics about the number, type, and size of commercial buildings in the United States as well as their energy-related characteristics. These data are collected in the Commercial Buildings Energy Consumption Survey (CBECS), a national survey of buildings in the commercial sector. The 1992 CBECS is the fifth in a series conducted since 1979 by the Energy Information Administration. Approximately 6,600 commercial buildings were surveyed, representing the characteristics and energy consumption of 4.8 million commercial buildings and 67.9 billion square feet of commercial floorspace nationwide. Overall, the amount of commercial floorspace in the United States increased an average of 2.4 percent annually between 1989 and 1992, while the number of commercial buildings increased an average of 2.0 percent annually.

  15. Polymers in phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.C.; Brites, M.J.; Alexandre, J.H. [National Lab. for Energy and Geology, Lisbon (Portugal)

    2010-07-01

    Phase Change Materials (PCMs) which are the core of latent heat thermal energy storage systems are currently an area of investigation of increasing interest. Several substances differing in physical and chemical characteristics as well as in thermal behavior have been studied as PCMS{sup 1-3}. In order to meet the requisites of particular systems, auxiliary materials are often used with specific functions. This bibliographic survey shows that polymeric materials have been proposed either as the PCM itself in solid-liquid or solid-solid transitions or to perform auxiliary functions of shape stabilisation and microencapsulation for solid-liquid PCMs. The PCMs have an operating temperature ranging from around 0 C (for the system water/polyacrilamid) to around 127 C (for crosslinked HDPE). (orig.)

  16. A new atmospheric aerosol phase equilibrium model (UHAERO: organic systems

    Directory of Open Access Journals (Sweden)

    N. R. Amundson

    2007-09-01

    Full Text Available In atmospheric aerosols, water and volatile inorganic and organic species are distributed between the gas and aerosol phases in accordance with thermodynamic equilibrium. Within an atmospheric particle, liquid and solid phases can exist at equilibrium. Models exist for computation of phase equilibria for inorganic/water mixtures typical of atmospheric aerosols; when organic species are present, the phase equilibrium problem is complicated by organic/water interactions as well as the potentially large number of organic species. We present here an extension of the UHAERO inorganic thermodynamic model (Amundson et al., 2006c to organic/water systems. Phase diagrams for a number of model organic/water systems characteristic of both primary and secondary organic aerosols are computed. Also calculated are inorganic/organic/water phase diagrams that show the effect of organics on inorganic deliquescence behavior. The effect of the choice of activity coefficient model for organics on the computed phase equilibria is explored.

  17. A new atmospheric aerosol phase equilibrium model (UHAERO: organic systems

    Directory of Open Access Journals (Sweden)

    N. R. Amundson

    2007-06-01

    Full Text Available In atmospheric aerosols, water and volatile inorganic and organic species are distributed between the gas and aerosol phases in accordance with thermodynamic equilibrium. Within an atmospheric particle, liquid and solid phases can exist at equilibrium. Models exist for computation of phase equilibria for inorganic/water mixtures typical of atmospheric aerosols; when organic species are present, the phase equilibrium problem is complicated by organic/water interactions as well as the potentially large number of organic species. We present here an extension of the UHAERO inorganic thermodynamic model (Amundson et al., 2006c to organic/water systems. Phase diagrams for a number of model organic/water systems characteristic of both primary and secondary organic aerosols are computed. Also calculated are inorganic/organic/water phase diagrams that show the effect of organics on inorganic deliquescence behavior. The effect of the choice of activity coefficient model for organics on the computed phase equilibria is explored.

  18. Domain structure and phase transition in Sc-doped zirconia

    Science.gov (United States)

    Brunauer, G.; Boysen, H.; Frey, F.; Ehrenberg, H.

    2002-01-01

    The temperature dependence of the domain structure associated with the ferroelastic phase transition (Fm↔R bar 3 m) in ZrO2 doped with 11% Sc2O3 has been determined from a peak shape analysis of high-resolution synchrotron x-ray powder diffraction data. In the temperature region of coexisting phases the observed characteristic anisotropic broadening and asymmetry of the lines is modelled by three different phases: a main rhombohedral phase, a distorted rhombohedral phase with a smaller c/a ratio, and a cubic phase. The latter two are assigned to the internal structure of the domain walls between two adjacent twin domains. The size and amount of the cubic phase show an initially slow increase with temperature followed by a very steep increase and a slow one after that. The size of the (main) rhombohedral domains remains nearly constant, while (micro-) strain in the distorted regions gradually decreases.

  19. Quantum Enhanced Phase Retrieval

    CERN Document Server

    Liberman, Liat; Poem, Eilon; Silberberg, Yaron

    2015-01-01

    The retrieval of phases from intensity measurements is a key process in many fields in science, from optical microscopy to x-ray crystallography. Here we study phase retrieval of a one-dimensional multi-phase object that is illuminated by quantum states of light. We generalize the iterative Gerchberg-Saxton algorithm to photon correlation measurements on the output plane, rather than the standard intensity measurements. We report a numerical comparison of classical and quantum phase retrieval of a small one-dimensional object of discrete phases from its far-field diffraction. While the classical algorithm was ambiguous and often converged to wrong solutions, quantum light produced a unique reconstruction with smaller errors and faster convergence. We attribute these improvements to a larger Hilbert space that constrains the algorithm.

  20. Phase Contrast Imaging

    DEFF Research Database (Denmark)

    1996-01-01

    with a simple one-to-one mapping between resolution elements of a spatial phase modulator and resolution elements of the generated intensity pattern is provided. According to the invention a method is provided for synthesizing an intensity pattern with low loss of electromagnetic energy, comprising spatial...... modulation of electromagnetic radiation with a spatial phase mask for modulation of the phase of the incident eletromagnetic radiation by phasor values of individual resolution elements of the spatial phase mask, each phasor value being determined in such a way that the values of the Fourier transformed......The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation...