Dynamic stiffness for thin-walled structures by power series

INTRODUCTION Thin-walled structures have considerable tech-nological importance in many situations of engi-neering practice. The rotary and warping inertia terms should be considered in the analyses of thin-walled structures (Alwis and Wang, 1996), although it is difficult to obtain the analytical solutions of govern-ing differential equations, especially of thin-walled frame and spatial twisted structure. The finite element method (FEM) is widely used for vibration and sta-bility analy…     

Analysis of Penetration Model for Geo-Material by Rigid Projectile

Based on the cylindrical cavity expansion theory, a plastic-damage-elastic model is proposed for the penetration problem of geo-material. In the model, the unified strength criterion (Yu, 1991) is adopted as the failure criterion. The distributions of the radial stress and velocity are analyzed. According to the Newton's second law, a series results of the final penetration depth and the impedance load are obtained to different parameter b, when a rigid projectile normally impacts and penetrates a semi-infinite geo-material target with an impact velocity of 300-1200 m/s. By comparing with the test data available, it appears that the method can be used in analyzing the final depth and the impedance load of a rigid projectile penetrating into a semi-infinite target with different impact velocities.     

Study on Predrying by Spin Flash Dryer for Granulation

Spin flash dryer has the advantages of both fluidized bed dryer and pneumatic dryer. It has predominance in dealing with thermal sensitive materials. In this paper, the distribution of the air velocity in the spin flash dryer is discussed,which indicates that the rotating air in the dryer chamber can be divided into two areas,potential flow area and plane swirl area. Experiments show that air tangent velocity effects the process of granulation most remarkably. The radial distribution and moisture content of the particles have their intrinsic rules along either the diameter or height of the drying chamber. Besides, the operating parameters of predrying on bleaching powder are optimized. To meet the strict standard of the wet-pressing granulator on the moisture content of the feeder,a narrow lap is made at proper height in the wall of the drying chamber,where a chute and a rotating valve are installed in order to predry the filter cake and remove a part of water. Then the material is fed into the wet-pressing granulator.     

Multistage Extractive Reaction for Hydrogen Peroxide Production by Anthraquinone Process

The extractive reaction process of oxygen-working solution-water three-phase system for the production of hydrogen peroxide by the anthraquinone method was investigated in a sieve plate column of 50 mm in internal diameter. The oxidation reaction of anthrahydroquinone in the working solution with oxygen and the extraction of hydrogen peroxide from the working solution into aqueous phase occurred simultaneously in the countercurrent mode. The agitating effect caused by gaseous phase made the droplets of the dispersed phase become smaller, thus, increasing the liquid-liquid interfacial contact areas and resulting in the improvement of the mass transfer velocity. Results showed that the gas-agitation had a beneficial effect on the extraction of hydrogen peroxide from the working solution into the aqueous phase： the concentration of hydrogen peroxide in the raffinate decreased with the increase of the gaseous superficial velocities： and the concentration of H2O2 in the raffinate increased with the increase of the dispersed phase superficial velocity at the same superficial velocity of the gaseous phase. In the G-L-L extractive reaction process, with the increase of the gaseous superficial velocities, both the conversion of the anthrahydroquinone oxidation and the extraction efficiency of hydrogen peroxide first increased significantly, then increased gradually.     

Teaching method for reading views by analyzing lines and planes

1 Introduction a Reading views is one of the important and also challenging skills in learning engineering drawing. It is especially difficult to read the views of a cut object. Reading views by analyzing lines and planes is an effective method. However, …     

Hierarchical closed form solutions for plates bent by localized transverse loadings

3D and 2D closed form plate models are here applied to static analysis of simply supported square isotropic plates. 2D theories are hierarchically classified on the basis of the accuracy of the displacements and stresses obtained by comparison to the 3D exact results that could be assumed by the reader as benchmark for further analyses. Attention is mainly paid on localized loading conditions, that is, piecewise constant load. Also bi-sinusoidal and uniformly distributed loadings are taken into account. All of those configurations are considered in order to investigate the behavior of the 2D models in the case of continu- ous/uncontinuous, centric or off-centric loading conditions. The ratio between the side length a and the plate thickness h has been assumed as analysis parameter. Higher order 2D models yield accurate results for any considered load condition in the case of moderately thick plates, a/h=10. In the case of thick plates, a/h=5, and continuous/uncontinuous centric loading conditions high accuracy is also obtained. For the considered off-centric load condition and thick plates good results are provided for some output quantities. A better solution could be achieved by simply increasing the polynomial approximation order of the axiomatic 2D displacement field.     

Synthesis of Modified Epoxy Resin Undercoat for Resistor by Nano-SiO2

A kind of undercoat for resistor with high temperature and humidity resistance was obtained by modifying epoxy resin with proper nano-SiO2 added at 80 ℃. The structure, thermal stability, humidity resistance, and morphological characteristics of the modified epoxy resin undercoat were studied by electrical tests, infrared spectra (IR) analysis, and scanning electron microscopy (SEM). The results show that more compact and steady inter-crosslinked network structures are formed in the modified epoxy resin undercoat added with nano-SiO2, which greatly improves the performance of modified epoxy resin undercoat. The undercoat with nano-SiO2 of about 2.71%, kept for six months at room temperature without flocculating and aggregating, is of good stability, and the surface of painted resistor is uniform, tight and without air holes on it. The varying ratio of resistance with such undercoat painted is less than one in a thousand after high temperature and humidity resistance tests.     

Teaching for Creativity by Science Teachers in Grades 5–10

This classroom observation study explored how science teachers (N = 22) teach for creativity in grades 5–10 in Oman. We designed an observation form with 4 main categories that targeted the instructional practices related to teaching for creativity: questioning strategy, teacher’s responses to students’ ideas, classroom activities to support creativity, and whole-lesson methods that foster creativity. An open-ended survey was also designed to explore participants’ justifications for their instructional decisions and practices. The findings indicate that the overall level of teaching for creativity was low and that participants’ performance was the highest for teacher’s responses to students’ ideas category and the lowest for classroom activities to support creativity category. We observed that a teacher-centered approach with instructional practices geared toward preparing students for examinations was dominant and that these science teachers were bound to the textbook, following cookbook-style activities. Participants believed that they did not have enough time to cover the content and teach for creativity and that they were not prepared to teach for creativity. Based on these findings, we recommend that programs be developed to prepare science teachers to teach for creativity.     

Ensemble learning HMM for motion recognition and retrieval by Isomap dimension reduction

INTRODUCTION Now more and more motion capture systems are used to acquire realistic human motion data. Due to the success of the Mocap systems, realistic and highly detailed motion clips are commercially available and widely used for producing animations of human-like characters in a variety of applications, such as simu- lations, video games and animation files. Therefore an efficient motion data recognition and retrieval technique is needed to support motion data processing, such as mot…     

Calculating magnetic shielding effectiveness for high-power dc comparator by magnetic circuit method

Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comparators when an external radial magnetic field is added. The mathematical relationship between the magnetic shielding effectiveness and the parameters of the magnetic shielding body were obtained. To verify the validity of the calculation method, we developped a procedure to measure the magnetic shielding effectiveness of the magnetic body by measuring the induction voltage of the detection winding instead of the magnetic intensity at a point in the magnetic shielding body, making the manipulation much easier. The result calculated with the magnetic circuit method turns out to be closer to the measured one compared with that calculated with a conventional algorithm proposed by Ren, suggesting that the magnetic circuit method is an applicable tool for estimating the toroidal cavity magnetic shielding effectiveness of a heavy current comparator when a radial magnetic field is added.     

A BOD-DO coupling model for water quality simulation by artificial neural network

A one-dimensional BOD-DO coupling model for water quality simulation is presented,which adopts Streeter-Phelps equations and the theory of back-propagation artificial neural network.The water quality data of Yangtze River in the Chongqing region in the year of 1989 are divided into 5 groups and used in the learning and testing courses of this model.The result shows that such model is feasible for water quality simulation and is more accurate than traditional models.     

Knock prediction for dual fuel engines by using a simplified combustion model

INTRODUCTIONDuetodwindlingfueloilreservesandthedesireforreducedpollutantemissions,naturalgas,whichisdominantlycomposedofmethane,hasbeennowwidelyusedasanalternativefuelininternalcombustionengines .Aconventionaldieselenginecanbeconvertedwithoutexcessiveincr…     

Are Prompts Provided by Electronic Books as Effective for Teaching Preschoolers a Biological Concept as Those Provided by Adults?

Research Findings: Prior research indicates that shared book reading is an effective method for teaching biological concepts to young children. Adult questioning during reading enhances children’s comprehension. We investigated whether adult prompting during the reading of an electronic book enhanced children’s understanding of a biological concept. Ninety-one 4-year-olds read about camouflage in 3 conditions. We varied how prompts were provided: (a) read by the book, (b) read by a researcher, or (c) given face to face by the researcher. There was an interaction between children’s initial vocabulary level and condition. Children with low vocabulary scores gave fewer camouflage responses than their high-vocabulary peers, and this effect was particularly pronounced in the book-read condition. Children’s executive function was also measured and discussed. Practice or Policy: Our findings indicate that under some circumstances electronic prompts built into touchscreen books can be as effective at supporting conceptual development as the same prompts provided by a coreading adult. However, children with low vocabulary skills may be particularly supported by adult-led prompting. We suggest that adult prompting be used to motivate children to test and revise their own biological theories. Once children have learned strategies for updating their concepts, electronic prompting may be useful for scaffolding children’s transition to using the strategies when reading alone.     

The problem with women? Challenges posed by gender for career guidance practice

Institutionalised discrimination continues to perpetuate deep rooted social divisions, with gender inequality persisting as a pervasive feature of labour markets across the world. Despite the depth and breadth of gender inequality, there is limited acknowledgement in career theory that the career support needs of women are distinctive. A qualitative international comparative study into the career trajectories of older women (aged 45–65) has been conducted across six countries (Australia, Argentina, Germany, Italy, England and South Africa). The results provide an international understanding of women’s careers and offer insight into career theory and practice for women that are culturally relevant.     

Ruled by hetero-norms? Raising some moral questions for teachers in South Africa

Thirty-eight countries in Africa regard homosexuality as punishable by law with South Africa remaining a standout country advancing constitutional equality on the basis of sexual orientation. In the context of homophobic violence, however, concerns have been raised about schools’ potential to improve the educational, moral and social outcomes for young people. In examining how some South African teachers normalize heterosexuality the paper raises questions about moral education in addressing homophobia. By drawing on interviews conducted with teachers across different social contexts, the paper shows how rights are limited by dominant constructions of heterosexual privilege mediated by a range of interlocking social processes including gender, race and culture. The paper argues that attention to the social and cultural influences in teachers’ account of homosexuality must feature in local designs of moral education. The imperative of working with teachers is presented as a way forward to facilitate the broadening of moral education to include an interrogation of heteronormativity which has evaded the focus of South African moral education.     

Pigeons’ memory for empty time intervals marked by visual or auditory stimuli

In Experiment 1, pigeons were trained to discriminate the duration (2 or 8 sec) of an empty interval separated by two 1325-Hz tone markers by responding to red and green comparison stimuli. During delay testing, a choose-short bias occurred at 1 sec, but a robust choose-long bias occurred at 9 sec. Responding in the absence of tone markers indicated that the pigeons were attending to the markers and not simply timing the total trial duration. The birds were then trained to match short (2-sec) or long (8-sec) empty intervals marked by light to blue/yellow comparisons. For both visual and auditory markers, delay testing produced a choose-short bias at 1 sec and a choose-long bias at 9 sec. In Experiment 2, the pigeons were shifted from a fixed to variable intertrial intervals (ITI) within sessions. On trials with tone markers, the duration of both the empty interval and the preceding ITI affected choice responding. On trials with light markers, only the duration of the empty interval influenced choice responding. Subsequent delay testing in the context of variable ITIs replicated the memory biases previously obtained. In Experiment 3, performance was assessed at various delay intervals on trials in which either the first or the second marker was omitted. The data from these omission tests indicated that the first marker initiated timing but that the second marker sometimes initiated the timing of a new interval. Explanations of these effects in terms of the internal clock model of timing are discussed, and a simple quantitative model of the delay interval data is tested.     

“I Went by Twos,He Went by One”: Multiple Interpretations of Inscriptions as Resources for Mathematical Discussions

This article examines a classroom discussion of multiple interpretations of the scales on two distance versus time graphs. The analysis describes how two students and a teacher used multiple meanings for phrases of the form “I went by” and coordinated these meanings with different views of the scales. Students' ambiguous and shifting meanings did not prove to be obstacles to this discussion. Instead, this teacher used student interpretations as resources, built on them, and connected them to canonical mathematical concepts—in particular by highlighting (Goodwin, 1994 Goodwin, C. 1994. Professional vision.. American Anthropologist, 96: 606–633. [Crossref], [Web of Science ®] , [Google Scholar]) a “unitized” (Lamon, 1994 Lamon, S. 1994. “Ratio and proportion: Cognitive foundations in unitizing and norming.”. In The development of multiplicative reasoning in the learning of mathematics, Edited by: Harel, G. and Confrey, J. 89–120. New York: State University of New York Press..  [Google Scholar], 1996 Lamon, S. 1996. The development of unitizing: Its role in children's partitioning strategies.. Journal for Research in Mathematics Education, 27(2): 170–193. [Crossref], [Web of Science ®] , [Google Scholar], 2007 Lamon, S. 2007. “Rational number and proportional reasoning: Toward a theoretical framework.”. In Second handbook of research in mathematics teaching and learning, Edited by: Lester, F. Jr. 629–667. Charlotte, NC: Information Age..  [Google Scholar]) view of the scales. Research in mathematics education describes teaching that promotes conceptual development as having two central features: One is that teachers and students attend explicitly to concepts, and the other is that students wrestle with important mathematics (Hiebert & Grouws, 2007 Hiebert, J. and Grouws, D. 2007. “The effects of classroom mathematics teaching on students' learning.”. In Second handbook of research on mathematics teaching and learning, Edited by: Lester, F. 371–404. Reston, VA: National Council of Teachers of Mathematics..  [Google Scholar]). Not only does this classroom discussion provide an example that it is possible to balance these two features, but the analysis provides the details of how instruction can simultaneously provide explicit attention to concepts while allowing students to wrestle with these concepts.     

Disciplining writing: the case for multi‐disciplinary writing groups to support writing for publication by higher degree by research candidates in the humanities,arts and social sciences

This article addresses multi‐disciplinary writing groups in supporting writing for publication for higher degree by research candidates in the Humanities, Arts and Social Sciences. Drawing on focus group discussions with postgraduate research students from the Faculty of Arts at Monash University in Australia who participated in the writing groups, it investigates the participants’ perceptions of the multi‐disciplinary nature of the groups and some of the benefits of sharing writing with fellow postgraduate research students from different fields of study. Discussing both the strengths and weaknesses of the multi‐disciplinarity of the groups as identified by participants, the authors suggest that such groups can provide a forum for postgraduates to develop their ‘professional’ academic identity and develop their writing beyond the context of their theses and can have some unexpected benefits to participants’ sense of themselves as disciplinary proponents. The multi‐disciplinary context is thus considered as providing a level playing field in which postgraduates may approach the writing process as a shared methodology, encompassing a suite of specialised but generic skills that cross‐disciplinary boundaries.     

A Practical and Efficient Procedure for Preparation of Oximes by Use of InCl3

InCl3 catalyzes the reaction of hydroxylamine hydrochloride with a number of aldehydes and ketones under solvent free condition to afford an efficient method for the synthesis of oximes.