Performance of a single-stage Linde-Hampson refrigerator operating with binary refrigerants at the temperature level of-60 ℃＊

The optimization of the performance of a single-stage Linde-Hampson refrigerator （LHR） operating with six different binary refrigerants （R23/R134a, R23/R227ea, R23/R236ea, R170/R290, R170/R600a and R170/R600） with ozone depletion potentials （ODPs） of zero was conducted using a new approach at the temperature level of-60℃. Among these binary refrig- erants, the 0.55 and the 0.6 mole fractions of R23 for R23/R236ea are the most prospective nonflammable ones for the medium and low suction pressure compressors, respectively. For these two kinds of compressors, the 0.6 and the 0.65 mole fractions of R170 for R 170/R600, respectively, are the most prospective binary refrigerants with low global warming potentials （GWPs）. The results of optimization of pressure levels indicate that the optimum low pressure value for coefficients of performance （COP） is achieved when the minimum temperature differences occur at both the hot and the cold ends of the recuperator at a specified composition and pressure ratio. Two useful new parameters, the entropy production per unit heat recuperated and the ratio of heat recuperating capacity to the power consumption of the compression, were introduced to analyze the exergy loss ratio in the recuperator. The new approach employed in this paper also suggests a promising application even to the optimization of the performance with multi-component refrigerants.     

教师专业发展研究——课例比较

数学教师的专业发展一直是数学教育研究的一个热门话题,ICMI研究系列15的主题就是“数学教师的专业教育和发展”（The Professional Education and Development of Teachers of Mathematics）．事实上,在四年一次的国际数学教育大会（ICME）上,“数学教师的在职培训、职业生活与专业发展”（Inservice education,professional life and development of mathematics teachers）已成为相对固定的一个研究课题（如ICME-10的TSG23,ICME11的TSG28）,     

Preface-- Special Part-issue of the International Symposium on Robotics and Mechatronics （ISRM 2009） Hanoi,Vietnam, Sept. 21-23, 2009 （p.231-269）

The International Federation for the Promotion of Mechanism and Machine Science （IFToMM） held the International Symposium on Robotics and Mechatronics （ISRM 2009） as the first in a series of conference events promoting robotics and mechantronics in the Asian IFToMM community. The first event was held in Hanoi University of Technology on Sept. 21-23, 2009     

关于Hadamard乘积行列式界的注记

指出了LI Yao．tang and ZHONG Cong-lei（“Some estimations for determinant of the Hadamard product of H-matrices”，“Journal of Computational Mathematics”，2005，23（4））得到的关于两个日一矩阵的Hadamard乘积的行列式的一个下界和陈神灿（“Some determinantal inequlities for Hadamard product of matrices”，“Linear Algebra Appl”，2003，368）的结论是等价的。应用置换相似下的Hadamard乘积的行列式的不变性，给出了较大的一个相应的下界。     

用于RFID读卡器的低旁瓣圆极化微带天线阵的设计

A low-sidelobe circularly-polarized （CP） microstrip patch array for 2.4 GHz radio frequency identification （RFID） readers is presented. The antenna array with a Chebyshev current distribution is composed of 6 microstrip elements. The CP operation is obtained by the quasi-square patch with difference in lengths of the two sides. The antenna has been investigated numerically and experimentally. Measured results show that the array has a Chebyshev pattern with the sidelobe level of -23 dB, the half-power beamwidth of 16° and an impedance bandwidth （S11 ≥-10 dB） of 130 MHz, which is suitable for RFID reader applications.     

Field demonstration of reduction of lead availability in soil and cabbage （Brassica Chinensis L.） contaminated by mining tailings using phosphorus fertilizers

A field demonstration of reduction of lead availability in a soil and cabbage （Brassica Chinensis L.） contaminated by mining tailings, located in Shaoxing, China was carried out to evaluate the effects of applications of phosphorus fertilizers on Pb fractionation and Pb phytoavailability in the soil. It was found that the addition of all three P fertilizers including single super phosphate （SSP）, phosphate rock （PR）, and calcium magnesium phosphate （CMP） significantly decreased the percentage of water-soluble and exchangeable （WE） soil Pb and then reduced the uptake of Pb, Cd, and Zn by the cabbage compared to the control （CK）. The results showed that the level of 300 g P/mE soil was the most cost-effective application rate of P fertilizers for reducing Pb availability at the first stage of remediation, and that at this P level, the effect of WE fraction of Pb in the soil decreased by three phosphorus fertilizers followed the order： CMP （79%）〉SSP （41%）〉PR （23%）; Effectiveness on the reduction of Pb uptake by cabbage was in the order： CMP （53%）〉SSP （41%）〉PR （30%）. Therefore our field trial demonstrated that it was effective and feasible to reduce Pb availability in soil and cabbage contaminated by mining tailings using P fertilizers in China and PR would be a most cost-effective amendment.     

工资·纪律·伙食——英美教育改革拾零

美国教师工资整俸停滞不前 2005年6月23日．全美教育协会（the National Education Association．NEA）在华盛顿总部公布了共计129页的最新美国教师工资研究报告《排名与评估——2004年州排名和2005年学校统计》（Rankings＆Estimates：Rankings of the States 2004 and Estimates of School Statistics 2005）显示,尽管目前美国的人学率在持续增长和许多学区面临着教师的长期短缺,然而在过去的十年中,美国教师的平均工资整体上并没有多少提高。     

Not yet where we want to be： South Africa＇s participation in SITES 2006

The International Association for the Evaluation of Educational Achievement （IEA） initiated the Second International Technology in Education Study （SITES）--A longitudinal large-scale international comparative survey on the use of information and communication technologies （ICTs） in schools. The goal is to understand how ICTs effect teaching and learning in schools. SITES 2006 was the third module in this program to determine how teachers use ICTs, and to find out how school and education system factors influence teachers＇ pedagogical orientation. SITES 2006 administered three questionnaires： one for school principals, one for technology coordinators, and one for mathematics and science teachers, around 400 schools in each of 23 education systems. The main study took place during 2005-2007. This paper describes the South African educational context, provides an overview of the South African participation, speculates on South Africa＇s future participation, and provides a comparative glimpse of the use of ICTs in South African mathematics and science classrooms.     

Rites of passage： A comparison of US,Malaysian and Brazilian adolescents

This study compares the life events perceived as ＂rites of passage＂ from adolescence to adulthood by respondents between the ages of 14 and 23 in 3 countries and discusses the possible influences of culture and globalization on these perceptions. Participants include： （1） 250 adolescents from the US （125 males and 125 females）; （2） 191 adolescents from southeastern Brazil （70 males and 121 females）; and （3） 163 adolescents from Malaysia （76 males and 87 females）. These adolescents ranked a variety of life events which may be perceived as indicative of adult status by completing a questionnaire about perceived rites of passage. Although there were similarities among the 3 groups, several differences also emerged. The most commonly noted indicator of adult status for Malaysian youth was physical maturity, followed by completing one＇s education. Participants from the US cited financial independence as the major indicator of adult status, while those from Brazil cited the ability to make important decisions independently from family and to take responsibility for others, such as children, aging parents or a spouse. Brazilian youth were significantly more likely to cite a love affair and voting in major elections as rites of passage than were participants from the other 2 countries. Participants from the US were significantly more likely to cite military service, and Malaysian youth were significantly more likely to consider completion of education and achieving physical maturity as rites of passage. Gender and age differences within groups were evident on some items, but these were not consistent across groups. Possible explanations for the differences between countries and implications for educators working with adolescents in rapidly changing societies are discussed.     

部分国家和城市的别称

1．Athens（雅典）——the City of Jasmines（茉莉花城） 2．Berne（伯尔尼）——the City of Clocksand Watches（钟表城） 3．Brazil（巴西）——the Country of Coffee（咖啡国） 4．Bulgaria（保加利亚）——the Country of Roses（玫瑰之国）     

Application of response surface methodology in medium optimization for pyruvic acid production of <Emphasis Type="Italic">Torulopsis glabrata</Emphasis> TP19 in batch fermentation

Response surface methodology （RSM） was used to optimize the fermentation medium for enhancing pyruvic acid production by Torulopsis glabrata TP19. In the first step of optimization, with Plackett-Burman design, ammonium sulfate, glucose and nicotinic acid were found to be the important factors affecting pyruvic acid production significantly. In the second step, a 23 full factorial central composite design and RSM were applied to determine the optimal concentration of each significant variable. A second-order polynomial was determined by the multiple regression analysis of the experimental data. The optimum values for the critical components were obtained as follows： ammonium sulfate 0.7498 （10.75 g/L）, glucose 0.9383 （109.38 g/L） and nicotinic acid 0.3633 （7.86 mg/L） with a predicted value of maximum pyruvic acid production of 42.2 g/L. Under the optimal conditions, the practical pyruvic acid production was 42.4 g/L. The determination coefficient （R^2） was 0.9483, which ensures adequate credibility of the model. By scaling up fermentation from flask to jar fermentor, we obtained promising results.     

从数学的角度来解释地球上昼夜长短的变化

这里我从几何的角度来分析地球上昼夜长短的变化。我们知道：太阳在地球表面的直射点在北回归线（23．5″N）和南回归线（23．5″S）之间来回移动．就形成了直射点在地球表面的运行轨迹。如图一．假如从北回归线（A）处开始，逐渐向南移动，到达赤道（B）后（约9月23日前后）。[第一段]     

You Are the Real Winner of the 2008 Olympic Games

StoryteIler：In front of the distinctive （ 独具匠心的） nest, there is a green lawn （草坪）. There are so many colorful flowers. -The green lawn looks very beautiful. Claws （爪） of animals leave a lot of prints （印迹）. which look like the maze （迷宫） of Disneyland. The 2008 Olympic Games for animals is going to begin soon. Every comer of the forest is full of happiness. Fuwa are going to join it. They prepare for the Olympic Games actively （积极地）.     

Development of the social network b-learning in the University of Alicante

This work describes the genesis, articulation and consolidation from 2007 of a social network of b-learning （blended learning） in the UA （University of Alicante） （Spain）, with the institutional backing of the Office of the Vice President for Education Technology and Innovation, and the momentum and advice of professor Angel Fidalgo （UNESCO （United Nations Educational, Scientific and Cultural Organization） chair for University of Management and Policy）. The social network currently has more than 25 teachers, working on different work linkages with the university, implementing or intending to apply the teaching methodologyb-learning during the course 2007-2008 in a variety of courses and degrees. To do so, several resource centers （blogs, wikis, Wimba Create （before CourseGenie）, etc.）, and digital platforms （Virtual Campus of the UA, Moodle, etc.） are used.     

Pre-service Physics Teachers＇ Conceptions of Nature of Science

Understanding of NOS （nature of science） appears as a prerequisite of a scientifically literate person. Promoting adequate understanding of NOS in pre-service physics teachers is, therefore, an important task of science educators. Before doing that, science educators must have information concerning their pre-service teachers＇ conceptions of NOS. This study used the MOSQ （myths of science questionnaire） to explore 17 pre-service physics teachers＇ conceptions of NOS. Commonly, these pre-service teachers expressed misunderstandings about NOS with respect to： （1） the relationship between theory and law; （2） science as cumulative; （3） subjectivity in science; （4） the scientific method; and （5） the relationship between science and technology. Science educators should consider and utilize these common misunderstandings as a basis of curricular framework for further improving pre-service physics teachers＇ understanding of NOS.     

国际英语外语教师组织(IOTEFL)成立

早在1967年．随着英语作为国际语言和世界各国对英语教学的重视,美国建立了TESOL（Teachers of English to Speakers of Other Languages）,英国建立了IATEFL（International Association of Teachers of English as a Foreign Language）,每年召开国际学术年会和专项研讨会,在其内部建立各种专业委员会（SIG）,定期出版刊物,引领着全世界英语教育教学。     

Determination of the volatile fraction of coal tar

The coal tar was qualitative and quantitative anMyzed by gas chromatography （GC） method. 74 components were identified exactly by gas chromatographY-mass spectrometry （GC-MS）. 31 components （37%） were quantitatively analyzed by gas chromatography-flame ionization detector （GC-FID）. The linearity, accuracy, precision, limit of detection （LOD） and limit of quantitative （LOQ） determination were inspected. The scope of quantitative analysis by CC was discussed. The experimental results of thermogravimetric analysis （TGA） proved that GC quantitative analysis of the coal tar was reliable.     

A quantum chemistry study on reaction mechanisms of SO2 with O3 and H2O2

Reaction mechanisms of SO2 with O3 and H2O2 were investigated using quantum chemistry ab initio methods. Structures of all reactants, products, and transition states were optimized at the B3LYP/6-311G＋（3df,2p） level, and energy calculations were made at the G2M level. SO2 reactions with O3 and H2O2 occurred by O-abstraction and OH-abstraction by SO2, respectively, at length forming SO3＋O2 （3Eg） and H2SO4. For SO2＋O3 reactions the barrier height was predicted to be 9.68 kcal/mol with a rate constant of 3.61 × 10^-23 cm^3/（molecule.s） at 300 K, which is below the experimental upper limit. The rate constant predicted for this reaction accords well with the one provided by National Institute for Standards and Technology （NIST） in 250-500 K. For SO2＋H2O2 reactions the barrier height was predicted to be 62.39 kcal/mol with a rate constant of 2.48× 10^-61 cm^3/（molecule.s） at 300 K.     

Analysis on spectral gain characteristics of PPMgLN based quasi-phase-matching optical parametric amplification

A deep understanding of the spectral gain characteristics of optical parametric oscillators （OPOs） and optical parametric amplifiers （OPAs） is important for a highly efficient optical parametric conversion. We numerically calculated the spectral gain characteristics of a quasi-phase-matching （QPM） parametric conversion process using the periodically poled 6% （mol/mol） MgO doped LiNbO3 （PPMgLN） as the nonlinear crystal. In the simulation we utilized the approach of a transformative matrix of the periodically poled nonlinear medium, which results from the small-signal approximation of three-wave mixed nonlinear equations. Numerical simulation results show that： （1） The full width at half maximum （FWHM） of the spectral gain of the parametric process becomes wider with the increase of parametric wavelength and reaches the maximum at degeneration; （2） The gain coefficient decreases gradually with the increase of parametric wavelength; （3） The spectral gain bandwidth decreases correspondingly with the increase of the nonlinear material length; （4） There exists an optimal parametric wavelength band, which is most suitable for the high gain parametric conversion when pumped by a laser source with a wide wavelength band, such as the high power fiber laser.