不同偏流角下潮流能水轮机水动力特性与熵产率分析

采用CFD与熵产理论相结合的手段,分析了不同偏流角对潮流能水轮机水动力特性的影响,发现偏流使无导管水轮机和导管水轮机输出功率及轴向推力均不同程度地降低,偏流20°时,两者功率最大下降率分别达到30.6%、16.8%,转子轴向推力最大下降率分别达到30.2%、19.8%。由于导管的聚流效应,不同偏流角下导管水轮机相比无导管水轮机仍保持较高的输出功率。在处于低叶尖速比时,直接耗散熵产损失对水轮机能量获取影响较大,此范围内总熵产损失较低;在高叶尖速比时,湍流耗散损失对水轮机能量获取影响较大,此范围内总熵产率随叶尖速比的增加而快速上升,导致水轮机输出率随叶尖速比的增加而不断下降。

达沙替尼衍生物的合成及其产率分析

[目的]制备达沙替尼丁二酸单酯衍生物(DAS⁃SA)并建立分析产率的方法。[方法]采用核磁共振氢谱法确认达沙替尼丁二酸单酯衍生物的合成并采用高效液相色谱法(HPLC),以DAS为对照品间接测定产物中DAS⁃SA的百分含量(即纯度),最后对该反应的产率进行计算。[结果]达沙替尼丁二酸单酯衍生物被成功合成,且反应条件较为温和,通过高效液相色谱法定量分析得到反应产率为71.16%。[结论]建立的高效液相色谱法对DAS衍生物进行定量分析具有快速高效、专属性好、准确度高等优点,可为达沙替尼衍生物的含量测定提供方法依据。

HCCI燃烧中NO与异辛烷相互作用简化动力学模型构建与分析（英文）

为了分析废气再循环中NO对HCCI燃烧的影响,本文构建了一个新的NO与异辛烷相互作用的化学动力学机理,包括167种组分和835个反应,其中异辛烷分支反应包括112种组分和467个反应。NO分支的子机理是在Anderlohr等人对NO与异辛烷详细机理研究的基础上根据路径分析而得到的。新IC_8H_(18)-NO机理的验证分为:IC_8H_(18)-NO分支机理验证了在激波管中温度范围为855-1269 K,压力范围为2-6 MPa,化学计量比为0.5和1.0条件下的着火延迟时间;IC_8H_(18)-NO机理验证了在HCCI发动机中NO添加浓度为0-500×10-6(体积分数),同时也发现不同的NO添加浓度对IC_8H_(18)-NO的HCCI燃烧的影响有所不同。因此,本文利用CHEMKIN PRO软件中的零维单区化学动力学模型,模拟了在不同NO浓度下NO对异辛烷燃烧影响。通过敏感性分析和产率分析,得出了NO添加后对异辛烷燃烧影响的关键性反应为R476。在IC_8H_(18)-NO燃烧初期通过R476产生活性基OH,从而体现对燃烧的促进作用。但是在NO添加浓度较大时,由于NO浓度较大结合活性基(如OH)的能力增强,进而NO对燃烧的促进作用被削弱。

Carbon Productivity Analysis to Address Global Climate Change

Developing low-carbon economy and enhancing carbon productivity are basic approaches to coordinating economic development and protecting global environment, which are also the major ways to address climate change under the framework of sustainable development. In this paper, the authors analyze the annual rate of carbon productivity growth, the differences of carbon productivity of different countries, and the factors for enhancing carbon productivity. Consequently, the authors clarify their viewpoint that the annual rate of carbon productivity growth can be used to weigh the efforts that a country takes to address climate change, and propose policies and suggestions on promoting carbon production.

Prediction Model of Data Envelopment Analysis with Undesirable Outputs

Data envelopment analysis (DEA) has become a standard non parametric approach to productivity analysis, especially to relative efficiency analysis of decision making units (DMUs). Extended to the prediction field, it can solve the prediction problem with multiple inputs and outputs which can not be solved easily by the regression analysis method.But the traditional DEA models can not solve the problem with undesirable outputs,so in this paper the inherent relationship between goal programming and the DEA method based on the relationship between multiple goal programming and goal programming is explored,and a mixed DEA model which can make all factors of inputs and undesirable outputs decrease in different proportions is built.And at the same time,all the factors of desirable outputs increase in different proportions.

Pattern Change and Regional Disparity Tendency of Cultivated Land Use in Jiangsu Province

The study has examined the tempo-spatial patterns of cultivated land use change in Jiangsu province. A principal component analysis （PCA） of 18 selected indicators of cultivated land use during the period 1970-2010 identified 2 main pat- terns of change in planting productivity and economic efficiency. A major shift from production-centered pattern to profit-oriented one occurred in 1984, the time of grain yield surplus and the mitigation of population pressure. In response to the impending Opened Market System, there was a notable tendency of higher efficiency and less productivity since 1997, as well as remarkable regional disparity of cultivated land use change spatially. It revealed a relative decrease in grain cropping share, crop- ping scale and cultivation intensity in South Jiangsu, especially in Tai-Lake region, and the reverse in North Jiangsu. Some suggestions for the future were finally dis- cussed from the above findings.

Expressions for Entropy Production Rate of Fuel Cells

On the basis of a general model of fuel cells, the entropy production rates of a fuel cell system under different conditions are derived by using theories of electrochemistry and thermodynamics. In order to analyze the influence of the irreversible losses existing in an actual fuel cell, the equivalent circuit of the fuel cell is introduced, so that the irreversible factor of the fuel cell may be determined directly as a function of the internal, leak and load resistances. Moreover, the maximum power output and efficiency of the fuel cell are calculated, the optimal operation of the fuel cell is discussed, and the matching condition of the load resistance is determined.

Study on microwave-assisted extraction of coal

The effect of different factors on coal extraction yield-temperature, solvent, coal type and irradiation time were investigated for different China coals under microwave-assisted extraction（MAE）. The results show that the optimum temperature for ethanol, acetone and THF are 393,373 and 373 K respectively and the extraction yield of THF is higher than that of other two solvents under MAE. Extraction with several single organic solvents were conducted for the 5 typical China coals-Shenfu, Tongchuan, Panzhihua, Yitai and Huating coal under microwave-assisted extraction and Soxhlet extraction. Results indicat that extraction yield of ethylenediamine, ethanol, acetone, tetrahydrofuran under MAE are all higher than that of Soxhlet extraction and MAE required less time. Tongchuan coal extracts of ethanol and acetone which were extracted by MAE and Soxhlet extraction were analyzed by GC/MS.

Entropy Analyses of Droplet Combustion in Convective Environment with Small Reynolds Number

This paper analyzes the entropy generation rate of simple pure droplet combustion in a tempera-ture-elevated air convective environment based on the solutions of flow, and heat and mass transfer between the two phases. The flow-field calculations are carried out by solving the respective conservation equations for each phase, accounting for the droplet deformation with the axisymmetric model. The effects of the temperature, velocity and oxygen fraction of the free stream air on the total entropy generation rate in the process of the droplet combustion are investigated. Special attention is given to analyze the quantitative effects of droplet deformation. The results re-veal that the entropy generation rate due to chemical reaction occupies a large fraction of the total entropy generated, as a result of the large areas covered by the flame. Although, the magnitude of the entropy generation rate per volume due to heat transfer and combined mass and heat transfer has a magnitude of one order greater than that due to chemical reaction, they cover a very limited area, leading to a small fraction of the total entropy generated. The en-tropy generation rate due to mass transfer is negligible. High temperature and high velocity of the free stream are advantageous to increase the exergy efficiency in the range of small Reynolds number (<1) from the viewpoint of the second-law analysis over the droplet lifetime. The effect of droplet deformation on the total entropy generation is the modest.

Assessing MODIS Land Cover Products over China with Probability of Interannual Change

Accurate and up-to-date land cover data are important for climate-change modeling. Quality assessment is becoming critical, as many satellite-based land cover products of differing scales have been released to meet the needs of scientific studies. In this study, the authors assessed the Moderate Resolution Imaging Spectroradiometer(MODIS) land cover products by analyzing the probability of interannual change from 2001 to 2012. The authors found that, cumulatively, 43.0% of MODIS land cover had changed over China from 2001 to 2012 at least once. Of this percentage, 12.1% was considered unreasonable change, 6.1% was considered reasonable change, and areas of confusion accounted for about 24.8%, giving rise to great uncertainty in the products. MODIS Collection 51 products clearly have less uncertainty than the Collection 5 products. Areas of reasonable change occurred in transition zones of ecological, biophysical, and climate gradients, while areas of unreasonable change appeared in heterogeneous landscapes. The misclassifications at three spatial scales of horizontal grids used in regional climate models occurred largely in the heterogeneous landscapes, and the areal percentage of misclassification decreased with larger horizontal grid spacing. In addition, the misclassifications in MODIS products often occurred among specific classes, which are geographically, ecologically, and spectrally similar, with low discriminative spectral-temporal signals. The effect of classification uncertainty should be made known, and further improvements are still needed for application in regional climate models. The authors' findings have important implications for better understanding the uncertainties of MODIS land cover products, and for improving the land surface parameterization for regional climate models.

Clinical analysis of 322 cases of placenta previa

In recent years, the incidence of placenta previa has been increasing. According to the literature, it is mainly related to induced labor, artificial abortion, cesarean section, high aging pregnancy, multipara or smoking. The placenta previa is the chief cause of bleeding in late pregnancy and threatens the lives of mother and infant, resulting in a high risk problem in obstetrics. This article studies 322 cases of placenta previa from my hospital and Dalian Obstetrics and Gynecological Hospital from January, 2002 to July, 2009, on the basis of clinicretrospective analysis, in order to deepen our understanding and art of treating placenta previa. The study revealed that: 1. With 322 cases of placenta previa, the incidence was 0.73%. It was higher than the incidence 0.3% reported abroad and lower than the incidence 0.94% reported in our country. The data were from sampling survey and did not prove relations between placenta previa and ages, different from the result obtained abroad in which placenta previa had relation with pregnancy ages. The outcome needs further study. But artificial abortion, induced labor, cesarean section and multipara clearly influence the incidence. The study did not analyze the relation between smoking and placenta previa, but there was external data proving that smoking was related to placenta previa; 2. Ultrasound-B is a better method for examination at present; 3. In cases of vaginal childbirth there was a higher incidence of lateral placenta previa and partial placenta previa. The conservative temporization and timely cesarean section can greatly decrease the mortality of mother and infant.

Pyrolysis and co-pyrolysis of lignite and plastic

The study firstly discusses the pyrolysis characteristics and kinetics by thermogravimetric analysis （TGA）, and then investigates the pyrolysis of lignite and co-pyrolysis with plastic （polyethylene or polypropyl- ene） in tube furnace. Meanwhile, the research focuses on the co-pyrolysis products under different mix- ing ratios as well as pyrolysis products at different testing temperatures and heating rates. The results show that higher final testing temperature and lower heating rate contribute to bond fission in lignite pyrolysis, resulting in less char product. In co-pyrolysis, lignite acts as hydrogen donor, and the yields of char and water rise with increasing amount of plastic in the mixture, while the yields of gas and tar decrease; and a little admixture of plastic will promote the production of gas and tar. Kinetic studies indi- cate that in temperature range of 530-600℃, activation energies of lignite are higher than those of lig- nite/plastic blends, and as plastic mass ratio increases from 0% to 10%, samples need less energy to be decomposed during co-pyrolysis.

Emergency contraception:What is new?

Unintended pregnancy rates remain high throughout the World and increase the risk of poor maternal and infant outcomes.Most of unintended pregnancies occur in women who were not using contraceptionor who became pregnant despite the reported use of contraception.Women who have had recent unprotected intercourse including those who have had another form of contraception fail are potential candidates for this intervention.Currently used em-ergency contraceptive methods are pills that contain combined estrogen-progesterone,only progestin,antiprogestins and copper intrauterine devices.The most common form of this type of contraception is oral progestin-only pills(levonorgestrel).The most effective method is copper intrauterine devices followed by anti-progestins and oral progestin-only pills.The major pathogenesis of oral emergency contraceptives is the prevention or delay of ovulation.Although conception is possible on only a few days of the cycle,emergency contraception is offered when indicated without regard to the timing of the menstrual cycle because of uncertainty in the timing of the ovulation.Levonorgestrel and E/P regimes are most effective as soon as possible after unprotected sexual intercourse.A linear relationship has been shown between ef-fectiveness and the time of dose.The effectiveness continues for 120 h,but it is recommended to be used within 72 h after intercourse.Intrauterine devices may prevent pregnancy when 5 d after ovulation.

Should State Capital Withdraw from Competitive Sectors?——An Analysis Based on the Efficiency of SOEs in the Wholesale Sector

That SOEs are inefficient is still a consensus in most economic literature. However, in recent studies, more and more arguments are made in favor of the efficiency of SOEs, yet existing empirical studies are mostly based on production industry data as samples. On the basis of adopting distribution samples and conducting a cross-sector comparison between the production industry and the distribution sector, this paper offers a multi-perspective empirical assessment on the efficiency of SOEs. Through the analysis of major JTnancial indicators and adopting the Data Envelopment Analysis-Malmquist index for total factor productivity comparison, we find that SOEs generally do not have any disadvantage in efficiency and their superior efficiency is particularly pronounced in the distribution sector as compared with production industry. Moreover, the high share and high efficiency of state capital in the wholesale sector needs particular attention. This paper employs case studies to reveal the positive correlation between the assets-heavy operation of state-owned wholesale firms and their profitability. The implications are as follows： policymakers must deliberate prudently before deciding to withdraw or increase state capital in various sectors; in the wholesale sector where state capital is more efficient, the functions of state capital can be bolstered by increasing its presence in the sector,＂ the notion that state capital must be withdrawn from competitive sectors cannot be adopted likely, nor should the benefits of asset-light operation be exaggerated.

Methane adsorption-induced coal swelling measured with an optical method

In order to quantify the effect of matrix shrinkage on reservoir permeability during coalbed methane production, coal samples from Huozhou, Changzhi and Jincheng areas in Shanxi province （classified as high-volatile bituminous coal, low-volatile bituminous coal and anthracite, respectively） were collected, and adsorption-induced coal swelling in methane were determined by an optical method at 40 ℃ and pressure up to 12 MPa. All three coals showed similar behavior-that swelling increased as a function of pressure up to about 10 MPa but thereafter no further increase in swelling was observed. Swelling in the direction perpendicular to the bedding plane is greater than that parallel to the bedding plane, and the differences are about 7.77-8.33%. The maximum volumetric swelling ranges from 2.73% to 3.21 %-increasing with increasing coal rank. The swelling data can be described by a modified DR model. In addition, swelling increases with the amount of adsorption. However, the increase shows a relatively slower stage followed by a relatively faster stage instead of a linear increase. Based on the assumption that sorption-induced swelling/shrinkage of coal in methane is reversible, the permeability increases induced by coal shrinkage during methane desorption was analyzed, and the results indicate that the permeability change is larger for higher rank coal in the same unit of pressure depletion.

Novel kinetic model for the simulation analysis of the butanol productivity of Clostridium acetobutylicum ATCC 824 under different reactor configurations

Acetone–butanol–ethanol(ABE)fermentation process can be exploited for the generation of butanol as biofuel,however it does need to overcome its low volumetric solvent productivity before it can commercially compete with fossil fuel technologies.In this regard,mathematical modelling and simulation analysis are tools that can serve as the base for process engineering development of biological systems.In this work,a novel phenomenological kinetic model of Clostridium acetobutylicum ATCC 824 was considered as a benchmark system to evaluate the behaviour of an ABE fermentation under different process configurations using both free and immobilized cells:single stage batch operation,fed-batch,single stage Continuous Stirred Tank Reactor(CSTR)and multistage CSTRs with and without biomass recirculation.The proposed model achieved a linear correlation index r^2=0.9952 and r^2=0.9710 over experimental data for free and immobilized cells respectively.The predicted maximum butanol concentration and productivity obtained were 13.08 g·L^(-1)and 1.9620 g·L^(-1)·h^(-1)respectively,which represents an increase of 1.01%and 990%versus the currently developed industrial scale process reported currently into the literature.These results provide a reliable platform for the design and optimization of the ABE fermentation system and showcase the adequate predictive nature of the proposed model.

The Driving Forces of CO2 Emission in China： 2002-2007

This paper provides a computation on both the China＇s aggregate CO2 emission volume and the emission of each sector over the period of 2002-2007, based on the input-output analysis. Further analysis is also given on the various determinants of the change in the emission volume, with the aid of structural decomposition analysis （SDA） based on a residual-free method. Based on the input-output table of China in 2002 and 2007, the merge of sectors and the adjustment of price change have been made during the study. The emissions of carbon dioxide in China increased from 2,887.3 million ton to 5,664.6 million ton during 2002-2007. The average rate of increase is 13.3%, faster than the average rate of gross domestic product （GDP） growth 11.6% slightly. According to the process of SDA, the changes in emission are analyzed in terms of four different factors. Among the four factors studied in the paper, it is found that the change of emission intensity and structure of demand are the main reason of the decrease of emission, while production technology and scale effect increase the emission volume. The paper also finds that although the direct emission intensity decreased during the study period, the total emission intensity increased with the annual rate of 3.8%, which reflects the result of energy policy is not equal in different sectors.

Design of a Hydraulic System for Liquid Packaging

The paper analyzes the dynamic behaviour of an industrial system devoted to the automated hydraulic packaging of beverages. More in detail, a lumped and distributed numerical approach is used to model both the filling system and the multi-actuators hydraulic circuit needed to shape and separate the packages. The model reliability and accuracy are addressed by means of a numerical vs. experimental comparison of the main hydraulic and mechanical quantities for an actual production rate. Afterwards, the system architecture is redesigned in order to obtain higher production rates, and the effects of the hydraulic behaviour variation on the hydraulic efficiency are highlighted. Finally, a sensitivity analysis with respect to the main design parameters is carried out, in order to determine the circuit layout that maximizes the system efficiency in the whole production-rate range.

Analysis of Correlational Behavior of Solvent and Insolvent Firms Based on Accounting Ratios

The concept of crisis evolution is still not fully understood, despite over 40 years of research into investigations in the field of crisis and insolvency prediction. This is due to the fact that the financial situation of a firm changes within an unobservable life cycle continuum, comprising different economic states which are not in fact properly defined. The aim of this study was to contribute towards a better understanding of the differences between solvent and insolvent finns for the periods of one and two years prior to insolvency respectively. Through the application of correlation and factor analysis, an attempt was made to detect behavioral pattems in accounting ratios, which can in turn explain differences and similarities between the two groups of finns. The results of this study show that although accounting ratios from two consecutive years had low correlations for both groups of finns, they were much higher for insolvent firms. This provides evidence that the economic and financial situation of insolvent firms is much more dependent on its history when compared to solvent firms. Moreover, there is evidence to suggest that the change of the economic and fmancial situation of insolvent firms within the life cycle continuum tends to follow a predetermined path, in contrast to the more random nature of a solvent firm＇s behavior. Additionally, the results showed that the factor loadings for solvent and insolvent finns differ for both observation periods, indicating that there are different underlying factors affecting the final outcomes for the two groups of firms. This is mainly attributable to disturbances in the scaling factors of total assets for both observation periods, as well as the disappearing size factor for the pre-distress year for insolvent firms, based on factor analysis.