bluuebunny/crossref_metadata_2025 huggingface dataset:
Minimum flexural ductility design of high-strength concrete beams
Authors: Ho J. C. M. , Kwan A. K. H. , Pam H. J.
Published: October 2009

In the flexural design of reinforced concrete beams, apart from the provision of adequate strength, it is also necessary to provide a certain minimum level of ductility. Traditionally, this has been done by limiting the tension steel ratio or the neutral axis depth to no more than certain fixed maximum values. However, this would result in a variable level of curvature ductility depending on the concrete grade and the steel yield strength. Of greater concern is that this would lead to a lower level of curvature ductility than has been provided in the past to beams made of conventional materials when high-strength concrete and/or high-strength steel are used. It is proposed herein that instead of limiting the tension steel ratio and the neutral axis depth, it is better to set a fixed minimum to the curvature ductility factor. The maximum values of tension steel ratio and neutral axis depth corresponding to the proposed minimum curvature ductility factor for various concrete grades and steel yield strengths have been evaluated. Based on these maximum values, simplified guidelines for providing minimum flexural ductility have been developed.
Prediction of the lateral pressure exerted by self-compacting concrete on formwork
Authors: Vanhove Y. , Djelal C. , Magnin A.
Published: October 2009

This study concerns the prediction of lateral pressure exerted by self-compacting concrete (SCC) on formwork during the casting process. This estimation is obtained using Janssen's model as used in the statics of ensiled granular material. The model has been adapted to SCC. The friction coefficient between the concrete and the wall occurring in the model is measured with a new type of tribometer. The case of SCC placed in 12 m high formwork by three companies using two different techniques is presented. Comparison of the predicted results with on site measurements shows good agreement.
Flexural layered deformational model of reinforced concrete members
Authors: Kaklauskas G.
Published: October 2009

Based on a method recently proposed by the author and his co-workers, new average-stress/average-strain relations of cracked tensile concrete have been derived from experimental moment–curvature diagrams of under-reinforced concrete beams reported in the literature. Using these and previously obtained relations, a new constitutive relationship of cracked tensile concrete has been proposed for short-term deformational analysis of flexural reinforced concrete members. The stress–strain relationship, called the Flexural, accumulates tension-softening and tension-stiffening effects. A quantitative dependence has been established between the length of the descending branch and the reinforcement ratio. The Flexural constitutive relationship has been applied in a simple engineering technique based on a layered approach and the principles of strength of materials. To assess the accuracy of the technique, deflections/curvatures have been calculated for a large number of experimental reinforced concrete beams reported in the literature. Comparison has been carried out with well-known constitutive relationships and design code methods such as the ACI, EC2 and SNiP (Russian code).
A method for constructing the bilinear tension softening diagram of concrete corresponding to its true fracture energy
Authors: Abdalla H. M. , Karihaloo B. L.
Published: October 2009

For the analysis of cracked concrete structures using the fictitious crack model two fracture properties of concrete are required, namely its true specific fracture energy GF and the corresponding tension softening relation σ(w). In a recent paper, the authors proposed a simple method for the determination of the true specific fracture energy of a concrete mix. In this paper a method is proposed based on the concept of a non-linear hinge for constructing a bilinear approximation of the tension softening relation consistent with the true specific fracture energy GF. The parameters of this bilinear approximation are inferred in an inverse manner. It is shown that this inverse identification procedure predicts accurate bilinear softening relations of concrete mixes tested in three-point bend and wedge-splitting modes.
Experimental study on fatigue strength of continuously reinforced concrete pavements
Authors: Kang Y.-J. , Park J. S. , Yoon K.-Y. , Han S.-Y.
Published: October 2009

A laboratory investigation was conducted to characterise and quantify fatigue life of continuously reinforced concrete pavement (CRCP) in Korea highway systems. Eight scale-sized specimens were made, based upon results of finite-element analyses and stress–strain curve comparisons. Rubber plates were used to simulate the cement-treated sub-base and the sub-grade below the concrete pavements. Initially static tests were performed to obtain magnitudes of static failure loads and to predict crack patterns before fatigue tests. The CRCP fatigue lives measured in the study were compared with the results of previous investigations by other researchers. The comparisons indicate that the fatigue lives of most specimens are very close to the results from equation of Vesic and Saxena (NCHRP Report 97, HRB, National Research Council, Washington, DC, 1970). The results obtained in the study can be used for maintenance and retrofit of the CRCP constructed in major Korea highway systems.
Peeling behaviour of reinforced concrete beams strengthened with CFRP plates under various end restraint conditions
Authors: Pimanmas A. , Pornpongsaroj P.
Published: October 2009

Reinforced concrete (RC) beams strengthened with externally bonded fibre-reinforced polymer (FRP) are shown to have higher flexural capacity compared to unstrengthened specimens. However, concrete cover or FRP peeling may occur before the beam can achieve enhanced capacity. Thus, the FRP efficiency can be greatly reduced due to this premature failure. This research presents an experiment programme conducted to examine the peeling behaviour of strengthened beams under various end restraint conditions. In the experiment, carbon fibre-reinforced polymer (CFRP) plates were applied to strengthen RC beams and carbon fibre-reinforced sheets were used as end wrapping material. Three different wrapping schemes, namely, U-, L- and X-wrappings were examined. Without wrapping, the FRP-strengthened beams showed little strength improvement over unstrengthened ones. For U-wrapped strengthened beams, end peeling could be prevented but shear-flexural peeling followed by premature concrete crushing took place instead. For L- and X-wrapped beams, neither end peeling nor shear-flexural peeling was observed and the beam failed in flexural concrete crushing mode.
Development of volcanic pumice based cement and lightweight concrete
Authors: Hossain K. M. A.
Published: October 2009

The results of investigations on the suitability of using volcanic pumice (VP) as cement replacement material and as coarse aggregate in lightweight concrete production are reported. Tests were conducted on cement by replacing 0–50% of cement by mass and on concrete by replacing 0–100% of coarse aggregate by volume. The physical and chemical properties of VP were critically reviewed to evaluate the possible influence on both fresh and hardened properties of cement and concrete. The standard tests on different mixtures of Portland cement and volcanic pumice powder (VPP) mixtures provided encouraging results, comparable to those for blended Portland fly ash cement, and showed good potential for manufacturing Portland volcanic pumice cement with higher setting time and low heat of hydration using up to 15% of VPP. The properties of volcanic pumice concrete (VPC) using different percentages of volcanic pumice aggregate were evaluated by conducting a comprehensive series of tests on workability, strength, shrinkage and permeability. It is concluded that VPC has sufficient strength and adequate density to be accepted as structural lightweight concrete. Design charts are presented to evaluate mix design parameters of VPC.
Modelling effects of corrosion on cover cracking and bond in reinforced concrete
Authors: Wang X. H. , Liu X. L.
Published: October 2009

Reinforcing bar corrosion leads to a reduction in steel cross-section, cover cracking and deterioration of the steel–concrete bond. A simple analytical model is proposed to demonstrate the consequences of corrosion product buildup around the bars. Critical attack penetration depth of reinforcing bar at the time of cover cracking is calculated. The corrosion pressure due to expansive action of corrosion products before and after corrosion cracking is also estimated. Further bar confinement reduction, change at the steel–concrete interface as well as rib deterioration of the deformed bars are considered in calculating the mechanical interactions between reinforcing bar and concrete. As a result, the bond strength of corroded bars is obtained. Then the load capacity of corroded reinforced concrete beams, designed to fail in bond, is calculated. Reasonably good agreement between experimental results and theoretical analyses is obtained.
Domain size as a parameter for studying the potential alkali–silica reactivity of chert-bearing aggregates
Authors: McNally C. , Richardson M. G. , Carr A. J. , Strogen P.
Published: October 2009

The presence of chert or flint in aggregates used for concrete manufacture has long been a source of concern in the context of alkali–silica reactivity. The global in-service performance of chert and flint-bearing aggregates, however, varies from innocuous to deleterious. This could be due to variations in the degree of crystallinity of the silica, which influences potential reactivity. Chert occurs in significant Irish sources of aggregate used for concrete, yet no cases of deleterious expansion have been reported in the Republic of Ireland to date. Many of these sources fail to conclusively demonstrate innocuous behaviour in the laboratory expansion tests despite satisfactory in-service behaviour. A previous X-ray diffraction study, employing quartz crystallinity index, had indicated a significant difference between Irish Carboniferous cherts and English Cretaceous flints. This paper reports a further study of crystallinity, correlated with mortar bar expansion tests, but employing both quartz crystallinity index and domain size in the characterisation of crystallinity. The influence of chert content was also studied. Twenty-three Irish aggregate sources were sampled, and petrographic analysis revealed that 17 of these contained chert. Three flint-bearing aggregates, from sources in England that had demonstrated alkali–silica reactivity, were also sampled. Chert and flint were extracted from the aggregate samples by a petrographer experienced in the field of concrete technology. Twenty-six distinct samples were successfully extracted from 13 of the Irish and the three English sources. X-ray diffraction testing confirmed the previous findings (using the quartz crystallinity indices) that the Irish cherts are more crystalline than the English flints. Domain size determination, however, showed that the difference in crystallinity of the national sets was less than that anticipated. The influence of chert content is advanced as a hypothesis to explain the apparent reactivity of Irish cherts in screening tests. The potential value of combining domain size and chert content determination in helping to classify aggregate reactivity is advanced for cases where in-service behaviour is in significant conflict with findings from standard laboratory tests.
Determination of stress–strain curves of concrete from flexure tests
Authors: Tan T. H. , Nguyen N. B.
Published: October 2009

A general procedure using a regression analysis approach has been developed to derive the stress–strain curves of concrete in the form of a polynomial expression from flexure tests. This procedure is applicable for different types of flexure test of concrete specimens, such as beams under pure flexure tests, columns under constant eccentric loading, and tests of C-shape specimens with neutral axis position controlled. In most cases, the derivation of the stress–strain curves of concrete using this procedure is simpler than others with the same approach. An experimental programme with different loading schemes was carried out. The stress–strain curves of concrete obtained from the test data using this procedure show good consistency. The results also show that it is possible to get the descending part of high-strength concrete further from the peak point using eccentric tests under normal testing conditions.
A semi-closed-form solution for chloride diffusion in concrete with time-varying parameters
Authors: Maheswaran T. , Sanjayan J. G.
Published: October 2009

Reinforcement corrosion in concrete is a worldwide problem and billons of dollars are spent each year on repair and replacement of reinforced concrete structures because of corrosion damage of reinforcement. Chloride induced corrosion is the major type of corrosion encountered in reinforced concrete. The corrosion is initiated in reinforcement when chloride diffuses through the concrete cover and the chloride concentration at the reinforcement reaches a critical threshold level. Fick's second law of diffusion is commonly used for one-dimensional chloride diffusion. A closed-form solution based on error function is commonly used to predict the chloride concentrations, if the diffusion coefficient (D) and surface chloride concentration (Cs) remain constant. This solution is not applicable when D and Cs vary with time, which is the case in real-life situations. The finite difference or finite element methods with specialised software are generally used to solve such problems. This paper reviews existing methods and presents an alternative method based on a general closed-form solution with varying D but constant Cs. To incorporate the effect of varying Cs, an adaptation of the closed-form solution is presented. This solution can be used without the use of finite difference method or special computer software to predict the chloride concentrations.
Analysis of interfacial shrinkage stresses in patch repairs
Authors: Mangat P. S. , O'Flaherty F. J.
Published: October 2009

This paper presents simple analytical expressions that predict the interfacial shrinkage stresses in a repair patch over time. Four repair materials (L2, L3, L4 and G1) were applied by spraying (gunite) to unpropped compression members of two highway structures, and their performance was monitored to approximately six months' age. The elastic moduli of all the repair materials, Erm, were greater than the elastic moduli of the substrate concrete, Esub. The mechanics of patch repair interaction with the substrate were established, and analytical models, based on an analogy of the bimetallic strip undergoing a drop in temperature, were developed. Basic properties of the repair material (elastic modulus, shrinkage and tensile creep) and substrate concrete (elastic modulus), and geometrical details of the repair patch, are required to analyse the interfacial stresses in the repair patch. Verification of the analytical procedures is based on the field data, and the results show a satisfactory correlation between the actual and predicted stress redistribution.
Shear strengthening of high-strength reinforced concrete beams using fibrous composites
Authors: Shannag M. J. , Al-Rousan R.
Published: October 2009

A series of seven rectangular high-strength concrete beams were tested under third-point loading to study the effectiveness of using externally applied high-strength steel fibre-reinforced concrete jackets (SFRC) as a method of strengthening shear deficient high-strength reinforced concrete beams. The overall response of the beams loaded up to failure, the onset of cracking, and crack development with increased load and ductility were described. Two types of steel fibres were used, brass-coated and hooked end with fibre content ranging from 1 to 4% and an aspect ratio of 40 and 60 respectively. The test results indicate that all beams strengthened with SFRC jackets displayed excellent shear behaviour. The ultimate shear strength of the strengthened beams was much higher (about 60%) than that of the reference beams, depending on the energy absorbed in debonding and stretching the fibres. The use of SFRC jackets transformed the mode of failure into a more ductile flexural one. A design procedure is suggested for a more accurate prediction of the shear capacity of the strengthened beams.
Strength properties of autoclaved and combined wet/dry-cured SBR-modified concretes using ground granulated blast-furnace slag
Authors: Joo M. , Ohama Y. , Yeon K. S.
Published: October 2009

The effects of slag content and polymer–binder ratio on the strength properties of autoclaved and combined wet/dry-cured SBR-modified concretes using ground granulated blast-furnace slag (GGBS) and styrene-butadiene rubber (SBR) latex are examined. As a result, the compressive and tensile strengths of the autoclaved and combined wet/dry-cured SBR-modified concretes using GGBS reach maxima at a slag content of 40%, and increase with increasing polymer–binder ratio. In particular, the autoclaved and combined wet/dry-cured SBR-modified concretes with a slag content of 40% and a polymer–binder ratio of 20% provide about three and two times higher tensile strengths than the same-cured unmodified concretes without GGBS, respectively. Such a high strength development is attributed to the improved bonds between cement hydrates and aggregates because of the incorporation of SBR latex.
Statistical analysis for strength properties of polypropylene-fibre-reinforced fly ash concrete
Authors: Karahan O. , Tanyildizi H. , Atis C.D.
Published: October 2009

In this study, the strength properties of polypropylene (PP)-fibre-reinforced fly-ash concrete were investigated experimentally and statistically. Three control factors (amount of fly ash, amount of PP fibre and curing time) were used for this study. The fly ash content that was used was 0, 60 and 120 kg/m3 and the fibre content was 0, 0·45, 0·90 and 1·80 kg/m3. The specimens were cured in standard curing conditions at temperature 23 ± 2°C for periods of 7, 28, 90 and 365 days. At the end of the curing period, the average of three specimens was tested to measure each of the concrete strength properties (compressive strength, flexural tensile strength and splitting tensile strength). Furthermore, the level of importance of these parameters on the strength properties was determined by using the analysis of variance (Anova) method.
Experimental study of recycled rubber-filled high-strength concrete
Authors: Li L.-J. , Chen Z.-Z. , Xie W.-F. , Liu F.
Published: October 2009

The performance of recycled rubber-filled high-strength concrete (RHSC) with different rubber contents (0%, 1%, 2% and 3%) and different rubber sizes such as 15-sieve size (1 mm), 40-sieve size (0·42 mm) and 60-sieve size (0·25 mm) was tested in this study, including the compressive strength, splitting strength, flexural strength, elastic modulus, stress–strain relationship and permeability of chloride ion. The test results show that the addition of rubber powder can reduce the strength of high-strength concrete, improve the capacity of energy absorbability, modify the brittleness and enhance the ductility of the high-strength concrete. An ultrasonic pulse non-destructive technique was used to investigate the RHSC. The relationships between the compressive strength and the pulse velocity of RHSC were presented, which can be used to foretell the strength of RHSC.
Fire performance of steel-reinforced concrete beam–column joints
Authors: Han L.-H. , Zheng Y.-Q. , Tao Z.
Published: October 2009

The present study is an investigation into the fire performance of steel-reinforced concrete (SRC) beam–column joints subjected to fire. Two new tests on SRC beam–column joints subjected to the ISO-834 fire standard were carried out and described. A finite-element analysis (FEA) modelling was developed. A comparison of results calculated using this modelling shows generally good agreement with the test results. The FEA modelling is then used to investigate the influence of important parameters that determine the mechanism of the composite joints under fire.
Contribution of fibres to the properties of EPS lightweight concrete
Authors: Chen B. , Fang C.
Published: October 2009

The effect of different fibres on the workability, mechanical properties, drying shrinkage and water adsorption was investigated on expanded polystyrene (EPS) lightweight concrete of high strength and workability. The results showed that the addition of fibres to the EPS lightweight concrete mixture during mixing substantially reduced the sedimentation of EPS beads and improved the uniformity of the mix as well. Compared with normal EPS concrete, fibres were demonstrated to have greatly increased strength, especially splitting tensile strength. It was also demonstrated that fibres restrained the long-term drying shrinkage. However, no significant effect was found of fibres on the water adsorption of EPS concrete.
Shear strength prediction of circular RC members by the crack sliding model
Authors: Jensen U.G. , Hoang L.C.
Published: October 2009

Reinforced concrete members with circular cross-section are widely used in bridge engineering, either as piers or as piles to support pile caps. Such members are often subjected to combined shear, bending and axial loading. Compared with the overwhelming studies of shear in rectangular members, relatively few theoretical studies of the shear resistance of circular members can be found in the literature. This paper presents a model that can be used to predict the shear strength of circular members. The model is an extension of the plasticity-based crack sliding model originally developed for rectangular beams. Analytical solutions for simply supported and restrained members are presented. The results obtained by the model have been compared with a large number of tests. Satisfactory agreement has been found.
Use of fibre sheet strip stirrups for internal shear reinforcement of concrete beams
Authors: Lee C. , Jeong S.M. , Park J.W.
Published: October 2009

In this research, experimental observations were made for the possible application of fibre sheet strips (FSS) as internal stirrups in place of fibre-reinforced polymer (FRP) rod stirrups currently being used for reinforced concrete beams. A total number of eight concrete beams were tested under three-point loading. Each beam measured 1200 mm long, 150 mm wide and 250 mm deep. Their shear span/depth ratios were 2·1. The beams were composed of different shear reinforcements: one without stirrups, one with steel stirrups and the rest with different types of FSS stirrups. Commercially available carbon fibre sheets were used for FSS stirrups. The main variables included strengthening bent portions of FSS stirrups, surface treatment and impregnation for FSS stirrups. Test results indicated that concrete beams reinforced with FSS stirrups enhanced shear strength over the beam without shear reinforcements. Moreover some of them could maintain comparable shear behaviour to that of the concrete beam reinforced with steel stirrups in overall load–deflection relationships, shear strengths, crack patterns and crack widths at maximum load.
Model study of dissipation of jets in deep wells
Authors: Al Naib S. K. , Vasanthakumaran R.
Published: October 2009

This paper presents an experimental investigation of a submerged round jet discharging vertically into a deep well. The research work was concentrated on two positions of the jet: (a) impingement at the centre of the well; and (b) impingement near the upstream side of the well. Square and rectangular shaped wells were tested for various pipe heights and well dimensions. Using a laser Doppler anemometer, velocity distributions were measured in the vertical and horizontal planes inside the well and compared with those for the free jet and the wall jet. The flow pattern and velocity decay of the jet were studied while varying the ratios of well height to pipe diameter between the practical limits of 6 to 16. Based on these results, an optimum size for a deep well has been indicated, with satisfactory prototype performance.
Enhanced energy dissipation in stepped chutes
Authors: James C. S. , Main A. G. , Moon J.
Published: October 2009

Energy dissipation by vertical steps in chutes and spillways can be enhanced by designing the steps to induce alternating lateral flow deflection, thereby causing collision between flow jets and side walls. Small-scale laboratory experiments using V-shaped step edges have shown that energy dissipation can be increased substantially in this way. The increase is proportional to the flow deflection induced, and is especially effective for transitional and skimming flow in steep stepped chutes.
A volume of fluid numerical model for wave impacts at coastal structures
Authors: Christakis N. , Allsop N. W. H. , Beale R. G. , Cooper A. J. , Dennis J. M.
Published: October 2009

The first stages in the development of a new design tool, to be used by coastal engineers to improve the efficiency, analysis, design, management and operation of a wide range of coastal and harbour structures, are described. The tool is based on a two-dimensional numerical model, NEWMOTICS-2D, using the volume of fluid (VOF) method, which permits the rapid calculation of wave hydrodynamics at impermeable natural and man-made structures. The critical hydrodynamic flow processes and forces are identified together with the equations that describe these key processes. The different possible numerical approaches for the solution of these equations, and the types of numerical models currently available, are examined and assessed. Preliminary tests of the model, using comparisons with results from a series of hydraulic model test cases, are described. The results of these tests demonstrate that the VOF approach is particularly appropriate for the simulation of the dynamics of waves at coastal structures because of its flexibility in representing the complex free surfaces encountered during wave impact and breaking. The further programme of work, required to develop the existing model into a tool for use in routine engineering design, is outlined.
Recent flood disasters in China
Authors: Wang Z.-Y. , Plate E. J.
Published: October 2009

In 1996 and 1998 several devastating floods occurred on the Yangtze, Yellow, Haihe and Songhua Rivers in China. Flood disasters are now happening more frequently than in the past, due to the fact that economic development is changing the river discharge and the flood control system has not matched the change. In recent years it has been found that small floods cause high stage and extreme damage on the Yellow and Yangtze Rivers, which is due to the non-integrated water and sediment management. On the Yellow River a flood in 1996 with a return period of two years caused the highest recorded stage in history and resulted in huge economic losses because the high rate of siltation and the increasing water diversion from the river had greatly reduced the flood discharge capacity of the river channel. In the Haihe River basin a 1-in-50-year flood in 1996 claimed fewer lives and less damage than in earlier times thanks to artificial drainage canals built in the 1960s and 1970s, which increased the capacity of the drainage system tenfold. New problems arise, however, because due to sediment carried by the tidal current from the sea, the channel outlets are congesting. On the Yangtze River an extreme flood occurred in 1998 which resulted in serious flood damage and affected 8 million people. It was primarily a result of abnormal heavy rainfall, but the flood stage was extremely high due to a reduced flood diversion, reduced regulation capacity of riparian lakes, and channel sedimentation. This paper describes recent flood events and discusses new strategies for flood control.
Towards homogeneity in homes languages
Authors: Ting Su-Hie , Mahadhir Mahanita
Published: October 2009

This preliminary study examines the languages used by parents with their children in Malay, Chinese Foochow and Indian Tamil families to find out how the similarity or dissimilarity in parents’ ethnic language influenced the choice of language transmitted to children and how far standard languages have permeated the family domain in Kuching City in the Malaysian state of Sarawak. Standard languages refer to the three main written languages taught in the school system, namely, English, Bahasa Malaysia (Malay language) and Chinese Mandarin. Interviews were conducted with 17 families (6 Malay, 6 Chinese Foochow, 5 Indian Tamil). The results showed that the ethnic language is mostly still retained in the Malay and Indian Tamil families but has been pushed out by English and Mandarin Chinese in Chinese Foochow families. English has emerged in parental communication with children to different extents across ethnic group. Bahasa Malaysia, on the other hand, is spoken in Malay families with parents from West Malaysia. Factors found to be influencing the parental decision on language to use with their children include similarity/dissimilarity of the couple’s ethnic languages, their educational background, family and social linguistic environment, instrumental value of languages and ethnic identity.
Perbla and Tolmin formations: revised Toarcian to Tithonian stratigraphy of the Tolmin Basin (NW Slovenia) and regional correlations
Authors: Rožič Boštjan
Published: October 2009

The succession of the Tolmin Basin forms the foothills of the Julian Alps in northwestern Slovenia. In the Jurassic, it was part of the southern Tethyan passive continental margin. The basin was located between the Dinaric Carbonate Platform in the south and the Julian High in the north. Six sections were studied that encompass the stratigraphic interval from the Toarcian to the lower Tithonian. The basinal background deposits are generally marl, siliceous limestone, and radiolarian chert, whereas in the southern part of the basin resedimented limestones occur. The studied succession lies between the Lower Jurassic Krikov Formation (resedimented and hemipelagic limestones) below and upper Tithonian to Neocomian Biancone Limestone above.

Two formations are described in this paper: (1) The Toarcian Perbla Formation was introduced by Cousin [1973] and is revised herein. It is composed of marl and subordinate calcareous shale with rare intercalated calciturbidites. The material was redeposited only within the basin or from its marginal parts. The thickness of the formation varies significantly through the basin from 2 to 135 metres; (2) The Tolmin Formation is herein defined. It is divided into two members. The lower member (Aalenian to lower Bajocian) consists of siliceous limestone and rare chert, whereas the upper member (upper Bajocian to lower Tithonian) is composed of radiolarian chert that locally in the upper part contains abundant marl intercalations. In the southern part of the basin, two intervals of resedimented limestones occur in the Tolmin Formation. The lower interval (lower Bajocian to lower Callovian) is dominated by calcarenite (rich in peloids and ooids) and limestone breccias. The upper interval (upper Kimmeridgian to lower Tithonian) is characterized by calcarenite, composed mostly of intraclasts and bioclasts. The source area of the carbonate material was the Dinaric Carbonate Platform.

The correlation of the background sediments with other basins of the western Tethys reveals that (1) the late Toarcian decrease in terrigenous input, the Bajocian change from calcareous to siliceous sedimentation and the late Tithonian onset of carbonate sedimentation are regional and (2) the silica content in the Tolmin Basin was higher than that in the western basins (e.g. the Belluno, Lombardian, Umbria-Marche and Subbetic basins) but lower than that in the Budva Basin. The Bajocian to Callovian resedimented limestones of the Tolmin Basin are much thinner than the corresponding deposits in the Belluno and Budva basins (25 metres vs. up to 600 metres) that bordered the Dinaric Carbonate Platform on the west and southwest respectively. This difference confirms the previously proposed interpretation that most of the carbonate production from the Dinaric Carbonate Platform was transported towards the southwest.
A Study of Student Interactions During Asynchronous Mathematical Problem Solving
Authors: Cooper Thomas E.
Published: October 2009

This study was conducted to investigate the quality and nature of the students' interactions during asynchronous online problem solving in two sections of College Algebra taught by the author. In a shared-work section, students worked independently for an initial phase and had access to classmates' work during a follow-up phase. Students in the other section worked on the same assignments in designated small groups. The student work was used to develop a general coding scheme for asynchronous interaction and a refined coding scheme to determine whether a student used classmates' work, the level of individual contribution, and the relative correctness of the solutions. In both sections, the students tended to work independently, using classmates' work to compare answers or get assistance, but the small-groups section displayed a higher level of participation and interaction, including traditional forms of interaction such as asking questions and responding to group members.
Assisting Teachers' Thinking and Participation Online
Authors: Kale Ugur , Brush Thomas , Saye John
Published: October 2009

This study examines online messages in a discussion forum that a group of K-12 history teachers used to discuss curriculum implementations as part of their professional development. It has 3 main research foci. First, it focuses on identifying the types of assistances provided to the teachers in an online forum. Second, it examines teachers' cognitive thinking levels exemplified in their online messages. Third, it investigates the relationship between the assistance provided to teachers and the thinking levels they exemplified online. In addition, the study presents data from interviews with forum users to help validate findings attained through examining the online messages. Findings show that various assistance types and forum users' perceptions of online communication may have influenced teachers' levels of thinking during online discussions.
Learner Autonomy as a Predictor of Course Success and Final Grades in Community College Online Courses
Authors: Yen Cherng-Jyh , Liu Simon
Published: October 2009

This study employed a quantitative research design to examine the predictive relationships between: (a) learner autonomy and course success; and (b) learner autonomy and final grades in community college online courses. Learner autonomy was defined as the characteristic of an individual who exhibited intentional behavior in learning activities. The results of the binary and ordinal logistic regression analyses suggested that learner autonomy was a valid predictor of course success and final grades in community college online courses. The implications of the results are discussed in the context of early identification and effective intervention. Specifically, two interventions are recommended: (a) blended learning programs, and (b) advisory and counseling services.
Tailoring Traditional Interviewing Techniques for Qualitative Research with Seriously Ill Patients about the End-of-Life: A Primer
Authors: Schulman-Green Dena , McCorkle Ruth , Bradley Elizabeth H.
Published: October 2009

Conducting qualitative interviews with seriously ill individuals about end-of-life issues is challenging for interviewers seeking to understand the problems, processes, and experiences individuals undergo when faced with death and dying. Although all qualitative interviewers face issues of building trust and obtaining answers to their research questions, these issues are exacerbated for interviewers of end-of-life issues due to the challenges of debilitated participants, sensitive subject matter, and heightened emotionalism. The purpose of this article is to offer field-tested techniques to tailor basic interviewing practices for discussions of end-of-life issues with seriously ill individuals. Use of tailored techniques facilitates the comfort of both interviewer and participant and enhances the probability of obtaining complete and accurate data, which in turn can improve the effectiveness of subsequent programs, policies, and clinical practice based on research findings.
Migration Dynamics and Seasonal Variation In the Biometrics of the Eurasian Curlew (Numenius arquata) Migrating through the Lower Vistula Valley (N Poland) in Autumn
Authors: Krupa Robert , Meissner Włodzimierz , Krupa Małgorzata , Sereda Agnieszka
Published: October 2009

Migration Dynamics and Seasonal Variation In the Biometrics of the Eurasian Curlew (Numenius arquata) Migrating through the Lower Vistula Valley (N Poland) in Autumn

The aim of this study was to present data on the phenology of autumn migration of the Eurasian Curlew passing the lower Vistula valley and to determine whether there is a difference in biometrics between early and late migrants, which may reflect different timing of migration of birds from different parts of the breeding range. Studies were conducted in the lower Vistula valley in 2003-2008. Median date of migration fell into 9-13 August pen-tade. The migration dynamics showed major day-to-day changes in bird numbers and almost all of observed flocks migrated without staying in the study area. Moreover, only one bird was caught twice during the season. It indicates that lower Vistula valley is not an attractive stopover site for Eurasian Curlews. There were significant differences in the total head lengths, bill lengths and body masses of birds caught in different ten-days periods with larger and heavier birds occurring towards the end of the study period (ANOVA, Neuman-Keuls test: p < 0.05 in all cases). The gradual increase in the total head and bill lengths and probably also in body mass indicates that bigger birds from the eastern part of the breeding range migrate later than smaller birds, which breed in the west. There were no significant differences in wing length, tarsus length and tarsus with toe length (ANOVA, Neuman-Keuls test: p > 0.05 in all cases). Subspecies N. a. arquata and N. a. orientalis have similar wing length and in this study there were no significant differences for this measurement between following decades of the studied period. Collected data suggest that the wing length, which had clearly bimodal distribution, should be the best linear measurements for sexing at least juvenile Eurasian Curlews.
Student Characteristics, Pre-College, College, and Environmental Factors as Predictors of Majoring in and Earning a STEM Degree: An Analysis of Students Attending a Hispanic Serving Institution
Authors: Crisp Gloria , Nora Amaury , Taggart Amanda
Published: October 2009

This study examined the demographic, pre-college, environmental, and college factors that impact students’ interests in and decisions to earn a science, technology, engineering, or mathematics (STEM) degree among students attending a Hispanic Serving Institution (HSI). Results indicated that Hispanic students were well represented among STEM majors, and students’ decisions to declare a STEM major and earn a STEM degree were uniquely influenced by students’ gender, ethnicity, SAT math score, and high school percentile. Earning a STEM degree was related to students’ first-semester GPA and enrollment in mathematics and science “gatekeeper” courses. Findings indicate that HSIs may be an important point of access for students in STEM fields and may also provide opportunity for more equitable outcomes for Hispanic students.
Development of an Inclined Plate Extractor-Separator for Immiscible Liquids
Authors: Munir Shahid , Daood Syed Sheraz , Ul Hassan Rizvi Syed Zahoor , Butt Muhammad Arif
Published: October 2009

A new inclined plates extractor-separator is developed for operation with immiscible liquids in which extraction and separation is achieved in one unit contrary to mixer settlers. The inclined plates extractor-separator combines turbulent jets for contacting, and an inclined plate for separation of the two phases. The inclined plates extractor-separator does not have any moving part inside the vessel. This feature makes it free from the mechanical problems associated with conventional apparatus. The proposed inclined plates extractor-separator was operated in batch mode under various operating conditions to evaluate its performance on the basis of extraction efficiency. Water (light phase) was used as solvent to extract ethyl acetate from a heavy phase pool of tetrachloroethylene and ethyl acetate. The ethyl acetate content was analysed using chromatography. A hydrodynamic study was carried out using high speed photography to understand the mechanisms occurring during mass transfer across the two phases. Furthermore, it was found that the proposed inclined plate extractor-separator reduces the overall operating time by 67% and consumes only 13% of the power in comparison to a mixer-settler. A hydraulic power consumption comparison with a mixer settler and a gullwing extractor-separator is also presented.
Dye-Sensitized Solar Cells Based on the Principles and Materials of Photosynthesis: Mechanisms of Suppression and Enhancement of Photocurrent and Conversion Efficiency
Authors: Koyama Yasushi , Miki Takeshi , Wang Xiao-Feng , Nagae Hiroyoshi
Published: October 2009

Attempts have been made to develop dye-sensitized solar cells based on the principles and materials of photosynthesis: We first tested photosynthetic pigments, carotenoids (Cars), chlorophylls (Chls) and their derivatives, to find sensitizers showing reasonable performance (photocurrent and conversion efficiency). We then tried to introduce the principles of photosynthesis, including electron transfer and energy transfer from Car to Phe a. Also, we tried co-sensitization using the pheophorbide (Phe) a and Chl c2 pair which further enhanced the performance of the component sensitizers as follows: Jsc = 9.0 + 13.8 → 14.0 mA cm–2 and η = 3.4 + 4.6 → 5.4%.
Challenges for the Development of New Non-Toxic Antifouling Solutions
Authors: Maréchal Jean-Philippe , Hellio Claire
Published: October 2009

Marine biofouling is of major economic concern to all marine industries. The shipping trade is particularly alert to the development of new antifouling (AF) strategies, especially green AF paint as international regulations regarding the environmental impact of the compounds actually incorporated into the formulations are becoming more and more strict. It is also recognised that vessels play an extensive role in invasive species propagation as ballast waters transport potentially threatening larvae. It is then crucial to develop new AF solutions combining advances in marine chemistry and topography, in addition to a knowledge of marine biofoulers, with respect to the marine environment. This review presents the recent research progress made in the field of new non-toxic AF solutions (new microtexturing of surfaces, foul-release coatings, and with a special emphasis on marine natural antifoulants) as well as the perspectives for future research directions.
Discrete Return Lidar in Natural Resources: Recommendations for Project Planning, Data Processing, and Deliverables
Authors: Evans Jeffrey  S. , Hudak Andrew  T. , Faux Russ , Smith Alistair M. S.
Published: October 2009

Recent years have seen the progression of light detection and ranging (lidar) from the realm of research to operational use in natural resource management. Numerous government agencies, private industries, and public/private stakeholder consortiums are planning or have recently acquired large-scale acquisitions, and a national U.S. lidar acquisition is likely before 2020. Before it is feasible for land managers to integrate lidar into decision making, resource assessment, or monitoring across the gambit of natural resource applications, consistent standards in project planning, data processing, and user-driven products are required. This paper introduces principal lidar acquisition parameters, and makes recommendations for project planning, processing, and product standards to better serve natural resource managers across multiple disciplines.
A Rigorous Temperature-Dependent Stochastic Modelling and Testing for MEMS-Based Inertial Sensor Errors
Authors: El-Diasty Mohammed , Pagiatakis Spiros
Published: October 2009

In this paper, we examine the effect of changing the temperature points on MEMS-based inertial sensor random error. We collect static data under different temperature points using a MEMS-based inertial sensor mounted inside a thermal chamber. Rigorous stochastic models, namely Autoregressive-based Gauss-Markov (AR-based GM) models are developed to describe the random error behaviour. The proposed AR-based GM model is initially applied to short stationary inertial data to develop the stochastic model parameters (correlation times). It is shown that the stochastic model parameters of a MEMS-based inertial unit, namely the ADIS16364, are temperature dependent. In addition, field kinematic test data collected at about 17 °C are used to test the performance of the stochastic models at different temperature points in the filtering stage using Unscented Kalman Filter (UKF). It is shown that the stochastic model developed at 20 °C provides a more accurate inertial navigation solution than the ones obtained from the stochastic models developed at −40 °C, −20 °C, 0 °C, +40 °C, and +60 °C. The temperature dependence of the stochastic model is significant and should be considered at all times to obtain optimal navigation solution for MEMS-based INS/GPS integration.
Optimal Sensor Location Design for Reliable Fault Detection in Presence of False Alarms
Authors: Yang Fan , Xiao Deyun , Shah Sirish  L.
Published: October 2009

To improve fault detection reliability, sensor location should be designed according to an optimization criterion with constraints imposed by issues of detectability and identifiability. Reliability requires the minimization of undetectability and false alarm probability due to random factors on sensor readings, which is not only related with sensor readings but also affected by fault propagation. This paper introduces the reliability criteria expression based on the missed/false alarm probability of each sensor and system topology or connectivity derived from the directed graph. The algorithm for the optimization problem is presented as a heuristic procedure. Finally, a boiler system is illustrated using the proposed method.
Activation of the Antiviral Kinase PKR and Viral Countermeasures
Authors: Dauber Bianca , Wolff Thorsten
Published: October 2009

The interferon-induced double-stranded (ds)RNA-dependent protein kinase (PKR) limits viral replication by an eIF2α-mediated block of translation. Although many negative-strand RNA viruses activate PKR, the responsible RNAs have long remained elusive, as dsRNA, the canonical activator of PKR, has not been detected in cells infected with such viruses. In this review we focus on the activating RNA molecules of different virus families, in particular the negative-strand RNA viruses. We discuss the recently identified non-canonical activators 5’-triphosphate RNA and the vRNP of influenza virus and give an update on strategies of selected RNA and DNA viruses to prevent activation of PKR.