高、低渗“串联”气层供气机理物理模拟研究

在国内低渗气田开发过程中,对非均质气层(近井高渗、外围低渗)供气机理认识还存在许多问题。利用物理模拟技术,结合苏里格气田单井地质模型,建立了平面非均质高、低渗气层“串联”物理模拟模型(“串联”模型)及实验方法,模拟研究了衰竭开发过程中非均质气层压力和产量变化规律、单井生产动态特征和配产对稳产期产气量的影响。

巧解“串联灯”(初三)

题在农村野外作业时,常使用“串联灯”作临时照明.所谓“串联灯”就是把额定电压为220伏的两只灯泡串联起来,接在380伏的电源上使用.

基于近场动力学的复杂界面双材料结构研究

为了将近场动力学方法应用于复杂界面的双材料结构,以锯齿形界面为例,基于PD“串联”键理论开发复杂界面双材料结构PD求解程序,通过单、双材料平板进行拉伸仿真分析,利用FEM解验证PD方法及程序的准确性。结果表明:PD方法在准静态模拟中具有较高的准确性。PD程序所得位移结果:在y=0.005 m处,x位移相对误差低于5%;在x=0 m处,y位移平均相对误差低于6.08%。程序所得位移结果在小模量比、小载荷下更准确。

Extraction Condition Optimization and Identification of Phenols from Lonicerae flos

Polyphenols were obtained from the natural dried Lonicerae flos by ultrasound-assisted extraction with ethanol as the solvent.Single factor experiment and response surface methodology were employed to optimize the extraction conditions.Ultra-performance liquid chromatrography(UPLC)-tandem mass spectrometry(MS/MS)was employed to identify polyphenols based on the plant widely targeted metabolomics database in a qualitative and quantitative manner.The results showed that the optimal extraction conditions for total phenols from Lonicerae flos were ultrasound-assisted extraction with a solid-to-liquid ratio of 10∶1 g/mL and 57%ethanol at 70 W and 60°C for 11 min.The yield of total phenols extracted under the optimal conditions reached 71.08 mg/g.The phenols in Lonicerae flos were mainly chlorogenic acid isomers,and the flavonoids were mainly nobiletin,galuteolin,and homoarbutin.

格非长篇小说《望春风》的叙事手法探析

格非在其长篇小说新作《望春风》中展现出中西合璧的成熟叙事技巧:经过从作为叙事材料的"本事"对象向作为更高级的艺术情节层面的升华转换,小说最终呈现出来的是一幅由按时间顺序排列事件的历时性基本面和按因果关系排列事件的共时性逻辑面相互交织而成的艺术画卷。其间既迷散着诸如散点透视、草蛇灰线等中国古典话本、章回小说叙事的漫漶色彩,又彰显着"轮回""元叙述""魔幻"等西方现代派、后现代派小说手法的先锋性表征。它成功地打破了传统与精英二元对立的叙事思维,有效地在叙事策略上令古典与现代卯榫在了一起。在叙事话语的层面,《望春风》也实现了长篇小说丰赡多元的话语"双声性"。

Failure characteristics of three-body model composed of rock and coal with different strength and stiffness

Four different types of three-body model composed of rock and coal with different strength and stiffness were established in order to study the failure characteristics of compound model such as roof-coal-floor. Through stress analysis of the element with variable strength and stiffness extracted from the strong-weak interface, the tri-axial compressive strength of the weak body and strong body near the interface as well as the areas away from the contact surface was found. Then, on the basis of three-dimensional fast Lagrangian method of continua and strain softening constitutive model composed of Coulomb-Mohr shear failure with tensile cut-off, stress and strain relationship of the four three-body combined models were analyzed under different confining pressures by numerical simulation. Finally, the different features of local shear zones and plastic failure areas of the four different models and their development trend with increasing confining pressure were discussed. The results show that additional stresses are derived due to the lateral deformation constraints near the strong-weak interface area, which results in the strength increasing in weak body and strength decreasing in strong body. The weakly consolidated soft rock and coal cementation exhibit significant strain softening behavior and bear compound tension-shear failure under uni-axial compression. With the increase of confining pressure, the tensile failure disappears from the model, and the failure type of composed model changes to local shear failure with different number of shearing bands and plastic failure zones. This work shows important guiding significance for the mechanism study of seismic, rock burst, and coal bump.

Bayesian and Multiple Bayesian Analysis of the Reliability Performances for Series System with Cold Standby Units

By using Bayesian and multiple Bayesian method, the failure probability, reliability and mean time to failure(MTTF) of series system with cold standby units are estimated. At last, we compare the two estimators by means of Monte_Carlo simulation.

Optimal quasi-periodic maintenance policies for two-unit series system

To investigate the effects of various random factors on the preventive maintenance （PM） decision-making of one type of two-unit series system, an optimal quasi-periodic PM policy is introduced. Assume that PM is perfect for unit 1 and only mechanical service for unit 2 in the model. PM activity is randomly performed according to a dynamic PM plan distributed in each implementation period. A replacement is determined based on the competing results of unplanned and planned replacements. The unplanned replacement is trigged by a catastrophic failure of unit 2, and the planned replacement is executed when the PM number reaches the threshold N. Through modeling and analysis, a solution algorithm for an optimal implementation period and the PM number is given, and optimal process and parametric sensitivity are provided by a numerical example. Results show that the implementation period should be decreased as soon as possible under the condition of meeting the needs of practice, which can increase mean operating time and decrease the long-run cost rate.

Identification of Pigments from Jujube Fruit Skin

[Objective]The aim was to identify the composition of pigments from Jujube fruit skin.[Method]Pigments were extracted from＇Lubei Dongzao＇,＇Lajiao Zao＇,＇Chengwu Dongzao＇,＇Dabailing＇and identificated by using high performance liquid chromatography-mass spectrometry（HPLC-MS）.[Result]The results showed that eight flavanols and four to five flavonols were detected,no anthocyanins was detected.The contents of flavonoids were differnt in four varieties.The contents of flavanols（11 mg/g） and flavonols（1.78 mg/g） in＇Dabailing＇ were one-time higher than other varieties.Quercetin 3 rutinoside was the major flavonol.[Conclusion]The research provided theoretical basis for further study on mechanism of Jujube pigment turnning into the red.

Determination of 10 Pyrethroids Pesticide Residues in Rice by GC-MS-MS

[Objective] A method was developed for the determination of 10 pyrethroids pesticide residues in rice by GC-MS-MS. [Method] Pyrethroids were extracted with acetonitrile, followed by a salting-out step with anhydrous magnesium sulfate and sodium chloride, cleaned up by florisil solid phase extraction （SPE） cartridge, and determined by multiple reaction monitoring mode. [Result] The method showed good linearity over the range of 0.010-0.500 mg/L for 10 pyrethroid pesticide with correlation coefficients over 0.99. The detection limits were 0.005 -0.010 mg/kg. The method was validated by analyzing samples spiked with 0.05, 0.10, 0.20 mg/kg of 10 pyrethroid pesticides, respectively. The average recoveries in rice ranged from 75.0-115.5%, and the relative standard deviations （RSD） were between 3.9%-6.9%. [Conclusion] The method is easy, accurate and reliable, which can meet the requirement for the simultaneous determination and confirmation of pyrethroid pesticide residues in rice.

Improved Design and SOVA Algorithm for Serial Concatenated Convolutional Code

To improve the performance of the short interleaved serial concatenated convolutional code(SCCC) with low decoding iterative times, the structure of Log MAP algorithm is introduced into the conventional SOVA decoder to improve its performance at short interleaving delay. The combination of Log MAP and SOVA avoids updating the matrices of the maximum path, and also makes a contribution to the requirement of short delay. The simulation results of several SCCCs show that the improved decoder can obtain satisfied performance with short frame interleaver and it is suitable to the high bit rate low delay communication systems.

Study of Electron Mobility in 4H-SiC Buried-Channel MOSFETs

The effects of several factors on mobility in 4H-SiC buried-channel （BC） MOSFETs are studied,A simple model that gives a quantitative analysis of series resistance effects on the effective mobility and field-effect mobility is proposed.A series resistance not only decreases field-effect mobility but also reduces the gate voltage corresponding to the peak field-effect mobility. The dependence of the peak field-effect mobility on series resistance follows a simple quadratic polynomial. The effects of uniform and exponential interface state distributions in the forbidden band on field-effect mobility are analyzed with an analytical model. The effects of non-uniform interface states can be ignored at lower gate voltages but become more obvious as the gate bias increases.

HYBRID EXCITATION CLAW-POLE SYNCHRONOUS GENERATOR WITH MAGNETIC CIRCUIT SERIES CONNECTION

To solve the low efficiency of electric excitation claw-pole synchronous generator（EECPSG） and regulate the magnetic field of permanent magnet （PM） claw-pole synchronous generator（PMCPSG）, a novel hybrid excitation claw-pole synchronous generator （HECPSG）with magnetic circuit series connection is proposed. Through the simulation study on the generator using the calculation method for magnetic circuit and 3-D finite element method （FEA）, the appropriate magnet thickness and the number of pole-pairs for the proposed generator are determined. Its off-loading characteristics, load characteristics, and regulation behaviors are investigated. The study shows that the appropriate number of pole-pairs in HECPSG with series magnetic circuits is two, and there exists an optimum magnet thickness. Compared to EECPSG, HECPSG realizes dual-directional control to the excitation current. Moreover, the generator can adjust the output voltage and keep the output voltage stable in a broad load range. Under the condition of same parametes, the motor has higer air-gap flux density and power density.

A Novel Technique of Parameter Extraction for Short Channel Length LDD MOSFETs

A novel parameter extraction technique suitable f or short channel length lightly-doped-drain (LDD) MOSFET's is proposed which seg ments the total gate bias range,and executes the linear regression in every subs ections,yielding the gate bias dependent parameters,such as effective channel le ngth,parasitic resistance,and mobility,etc.This method avoids the gate bias rang e optimization,and retains the accuracy and simplicity of linear regression.The extracted gate bias dependent parameters are implemented in the compact I-V model which has been proposed for deep submicron LDD MOSFET's.The good agreemen ts between simulations and measurements of the devices on 0.18μm CMOS technolo gy indicate the effectivity of this technique.

Rapid analysis and identification for the alkaloids from Ranunculus japonicus by UPLC /Q-TOF-MS

To establish a rapid and effective method for analysis and identification of the alkaloids from Ranunculus japoni- cus Thunb by ultra-performance liquid chromatogaraphy with quadruple-time-of-flight mass spectrometry （UPLC/Q-TOF- MS） and discuss their fragmentation regularity, the UPLC/Q-TOF-MS was used to identify the alkaloids from Ranunculus japonicus Thunb by their MS data, tandem characteristic fragment ions and standards. In the end, 12 alkaloids were identi- fied from Ranunculus japonicus for the first time, and their fragmentation regularity was discussed. Thus, a rapid and effec- tive analysis and identification method for the alkaloids from Ranunculus japonicus by UPLC/Q-TOF-MS is established.

Constitutive equations of 1060 pure aluminum based on modified double multiple nonlinear regression model

In order to study the work-ability and establish the optimum hot formation processing parameters for industrial 1060 pure aluminum, the compressive deformation behavior of pure aluminum was investigated at temperatures of 523?823 K and strain rates of 0.005?10 s?1 on a Gleeble?1500 thermo-simulation machine. The influence rule of processing parameters (strain, strain rate and temperature) on flow stress of pure aluminum was investigated. Nine analysis factors consisting of material parameters and according weights were optimized. Then, the constitutive equations of multilevel series rules, multilevel parallel rules and multilevel series &parallel rules were established. The correlation coefficients (R) are 0.992, 0.988 and 0.990, respectively, and the average absolute relative errors (AAREs) are 6.77%, 8.70% and 7.63%, respectively, which proves that the constitutive equations of multilevel series rules can predict the flow stress of pure aluminum with good correlation and precision.

Cloning, Characterization, and FISH Mapping of Four Satellite DNAs from Black Muntjac (Muntiacus crinifrons) and Fea’s Muntjac (M. feae)

Recent molecular cytogenetic studies demonstrate that extensive centromere-telomere fusions are the main chromosomal rearrangements underlying the karyotypic evolution of extant muntjacs. Although the molecular mechanism of tandem fusions remains unknown, satellite DNA is believed to have facilitated chromosome fusions by non-allelic homologous recombination. Previous studies detected non-random hybridization signals of cloned satellite DNA at the postulated fusion sites on the chromosomes in Indian and Chinese muntjacs. But the genomic distribution and organization of satellite DNAs in other muntjacs have not been investigated. In this study, we have isolated four satellite DNA clones （BMCS, BM700, BM 1.1 k and FM700） from the black muntjac （Muntiacus crinifrons） and Fea＇s muntjac （M. feae）, and hybridized these four clones onto chromosomes of four muntjac species （M. reevesi, M. crinifrons, M. gongshanenisis and M. feae）. Besides the predominant centromeric signals, non-random interstitial hybridization signals from satellite I and II DNA clones （BMC5, BM700 and FM700） were also observed on the arms of chromosomes of these four muntjacs. Our results provide additional support for the notion that the karyotypes of M. crinifrons, M. feae and M. gongshanensis have evolved from a 2n = 70 ancestral karyotype by a series of chromosome fusions.