bluuebunny/crossref_metadata_2025 huggingface dataset:
Does domestication mimic speciation? 1. A population-genetic analysis ofHordeum spontaneumandHordeum vulgarebased on AFLP and evolutionary considerations
Authors: Wei Yu Ming , Baum Bernard Rene , Nevo Eviatar , Zheng You Liang
Published: April 2006

To answer the question whether Hordeum spontaneum K. Koch. and Hordeum vulgare L. are conspecific taxonomic entities or not”, we carried out an investigation with amplified restriction fragment length polymorphism (AFLP™) using H. vulgare cultivars, H. spontaneum from the Fertile Crescent, and material from China, primarily Xizang (Tibet), containing landraces and accessions identified morphologically as Hordeum agriocrithon Åberg. and H. spontaneum. Population genetic analyses and discriminant analyses were based on three groupings, H. vulgare, H. spontaneum, and H. agriocrithon, determined from morphology. To independently find groups, cluster analyses were carried out followed by population-genetic analyses and discriminant analyses of the clusters. The results of population-genetic analyses of morphologically based groups were not very different from those of comparable analyses of groups inferred from clustering. Based on 795 AFLP bands scored on 506 individuals, genetic diversity was 30% higher within H. spontaneum than within H. agriocrithon or H. vulgare. The variation among the three entities was 27.3% (FCT= 0.27) and among populations within the three was 40.4% (FSC= 0.56) leaving 32.3% (FST= 0.68) within populations/accessions. Three entities were clearly defined by clustering and supported by discriminant analyses, and then nomenclaturally formulated, two as species and one as an interspecific hybrid. The first, H. spontaneum, comprises populations in the Near East, the second, H. vulgare, comprises the cultivars, and the third, H. ×agriocrithon, comprises all barley landraces and hybrids from China as well as hybrids from the Near East. We discuss evolutionary perspectives of speciation and conclude that barley cultivars form a species distinct from the wild progenitor, H. spontaneum. This analysis may highlight the dilemma regarding other cultivated plants and domesticated animals, a still unresolved evolutionary–taxonomic problem.
Meristem allocation and life-history evolution in herbaceous plants
Authors: Bonser Stephen P. , Aarssen Lonnie W.
Published: April 2006

Generalisations of life histories in plants are often framed in terms of allocation to reproduction. For example, relative allocation to reproduction is commonly found to be higher in semelparous than in iteroparous plant species. However, the association between vegetative traits and life history has been largely unexplored. In higher plants, reproductive and vegetative function can be measured in terms of meristem allocation. Under this approach, two vegetative traits (apical dominance (the suppression of axillary meristem development) and branching intensity (the commitment of axillary meristems to branches)) can be measured as well as one reproductive trait (reproductive effort). We used phylogenetically independent contrasts to compare reproductive and vegetative function in annual semelparous and perennial iteroparous species. Twenty congeneric species pairs (each species pair represented by one semelparous and one iteroparous species) across nine families were selected based on availability of herbarium specimens. Semelparous life-history evolution was associated with higher reproductive effort. Conversely, iteroparous life-history evolution was associated with higher apical dominance. Branching intensity was not associated with life history. An evolutionary association between life history and apical dominance but not branching intensity suggests a complex relationship between allocation to vegetative traits and the evolution of plant strategies across environments.
In vitro measurements of the competitive interactions between two saprobic basidiomycetes onTypha latifolia
Authors: Schulz Michael J. , Cahill, James F. , Currah Randolph S.
Published: April 2006

Psathyrella typhae (Kalchbr.) Pearson & Dennis forms small basidiomata (mushrooms) and Sclerotium hydrophilum Saccardo in Rothert numerous minute sclerotia at the base of senescent shoots of Typha latifolia L. To assess how the two might compete in nature, isolates of these fungi were paired on autoclaved leaf segments of T. latifolia and incubated at 15 and 25 °C. The relative abundance of each species in the segments was determined by macerating the leaf tissues and then transferring fragments of macerate to microplates containing two types of media: one conclusively demonstrated the presence of P. typhae while the other demonstrated the presence of S. hydrophilum. Relative numbers of microplate wells showing positive reactions for each species on each medium indicated the proportion of the segment occupied following single and paired inoculations. These data demonstrated that competition was asymmetric, with P. typhae the stronger competitor at both temperatures, and uninhibited by the presence of S. hydrophilum. In contrast, S. hydrophilum was competitively excluded by P. typhae.
Assessment of recent environmental changes in New Brunswick (Canada) lakes based on paleolimnological shifts in diatom species assemblages
Authors: Harris M. Anne , Cumming Brian F. , Smol John P.
Published: April 2006

New Brunswick lakes are subjected to multiple environmental stressors, such as atmospheric acid deposition and climate change. In the absence of long-term environmental data, the impacts of these stressors are not well understood. Long-term effects of environmental change on diatom species assemblages were assessed in the sediments of 16 New Brunswick lakes using paleolimnological approaches. A regional trend of increasing Cyclotella stelligera Cleve & Gunrow and decreasing Aulacoseira species complex was recorded in most lakes. Detailed paleolimnological analyses of Wolfe, Cundy, and West Long lakes revealed varying degrees of species change, with assemblage shifts beginning ca. 1900 CE (common era). These species trends are not consistent with acidification. However, linear regression of mean July temperature with time for two New Brunswick historical instrumental temperature records revealed statistically significant warming over the past century. The shift from heavily silicified tychoplanktonic Aulacoseira species to small planktonic diatom species, such as C. stelligera, is consistent with paleolimnological inferences of warming trends recorded in several other lake regions of the Northern Hemisphere. These assemblage shifts are likely due to recent climate change and may be mediated by reduced ice cover and (or) increased thermal stability (decreased lake mixing) during the open water period.
Influence of using a creep, rate, or an elastoplastic model for predicting the behaviour of embankments on soft soils
Authors: Gnanendran C T , Manivannan G , Lo S -CR
Published: April 2006

The predictability of the behaviour of an embankment constructed on a soft soil with three types of fully coupled finite element analysis models; namely a rate-formulated elasto-viscoplastic, a creep-formulated elasto-viscoplastic, and modified Cam clay (MCC) elastoplastic material model for the foundation soil is examined in this paper. The well documented geotextile reinforced Sackville test embankment was chosen for analyses using the three finite element models. Details of the analyses carried out using the three models and the results are discussed in comparison with field performance. All three models were found to be capable of predicting the behaviour of this embankment reasonably well. The creep model gave slightly better overall predictions of the behaviour compared to the rate and MCC models and therefore is considered to be better for predicting the time-dependent behaviour of this embankment. However, it requires the coefficient of secondary compression of the foundation soft soil as an additional input parameter and consumes more computing resources and time. In contrast, this study suggests that the MCC model is also capable of giving reasonably good overall predictions using less computing resources and time and therefore is sufficient for predicting the performance of embankments on soft soils.Key words: embankment, soft soil, geosynthetic reinforcement, analysis, viscoplasticity, creep.
Plane-strain lateral consolidation with non-Darcian flow
Authors: Sathananthan Iyathurai , Indraratna Buddhima
Published: April 2006

New plane-strain lateral consolidation equations are formulated that neglect the well resistance of vertical drains but are applicable for both Darcian and non-Darcian flow. The results of consolidation analyses using conventional Darcian (linear) flow and the new solution based on non-Darcian (exponential) flow are compared. A good match has been obtained between equivalent plane-strain and axisymmetric solutions. The advantage of the equivalent plane-strain procedure is that it not only matches the average degree of radial (axisymmetric) consolidation but also yields a more realistic excess pore pressure distribution in the lateral direction than the Darcian flow condition. The relevant parameters are illustrated graphically for convenience. Good agreement was obtained between the prediction of the new equivalent plane-strain solution and field data from a test area in Ska-Edeby, Sweden.Key words: plane strain, consolidation, soft clay, vertical drains.
Hydromechanical analysis of flow behavior in concrete gravity dam foundations
Authors: Gimenes Evandro , Fernández Gabriel
Published: April 2006

A key requirement in the evaluation of sliding stability of new and existing concrete gravity dams is the prediction of the distribution of pore pressure and shear strength in foundation joints and discontinuities. This paper presents a methodology for evaluating the hydromechanical behavior of concrete gravity dams founded on jointed rock. The methodology consisted of creating a database of observed dam behavior throughout typical cycles of reservoir filling and simulating this behavior with a distinct element method (DEM) numerical model. Once the model is validated, variations of key parameters including lithology, in situ stress, joint geometry, and joint characteristics can be incorporated in the analysis. A site-specific simulation of a typical reservoir cycle was carried out for Albigna Dam, Switzerland, founded on granitic rock, to assess the nature of the flow regime in the rock foundations and to evaluate the potential for sliding surfaces other than the damrock interface to develop. The factor of safety against sliding of various rock wedges of differing geometry present within the dam foundations was also evaluated using the DEM model and conventional analytical procedures. Estimates of crack propagation patterns and corresponding uplift pressures and factors of safety against sliding along the damrock interface obtained with the DEM were also compared with those from simplified procedures currently used in engineering practice. It was found that in a jointed rock, foundation uplift estimates after crack development obtained from present design guidelines can be too conservative and result in factors of safety that are too low and do not correspond to the observed behavior.Key words: hydromechanical, jointed rock, flow, dam design.
Dam ageing diagnosis and risk analysis: Development of methods to support expert judgment
Authors: Peyras Laurent , Royet Paul , Boissier Daniel
Published: April 2006

Diagnosis and risk analysis are essential to ensure the safety of dams. Dam specialist engineers have useful methods available to help them in their task: physical modelling for assessing dam stability, statistical analysis of dam monitoring data, and, more recently, functional modelling for operational safety analysis. However, an expert's judgment is necessary when the works are complex and unique, when data are imprecise or insufficient, and when preliminary diagnosis or detailed analysis are being made. Using their experience and knowledge, dam specialist engineers are able to provide recommendations to address specific problems. The authors propose methods to support expert diagnosis and risk analysis that capitalize on the expert's knowledge and feedback. Their approach is threefold: (i) an ageing functional model based on the failure mode and effect analysis (FMEA) method using a causal graph representation of ageing scenarios leading to loss of functions; (ii) a qualitative method of describing dam ageing historical data and representing trends in performance loss; and (iii) qualitative methods to assess the risk of performance loss of dams and their components. In terms of practical applications, our research has produced a knowledge database on dam mechanisms. Also, an ageing historical database was compiled from dams that have experienced deterioration. Finally, we are developing computer aids to assist engineers in diagnosis and risk analysis tasks.Key words: dam, diagnosis, risk analysis, ageing, criticality.
Simulating a direct shear box test by DEM
Authors: Liu S H
Published: April 2006

Distinct element simulation was performed for direct shear box (DSB) tests on a dense and a loose two-dimensional (2D) sample of 3259 cylinders. Special attention was devoted to the effect that the frictional force between the inside surface of the upper shear box and the sample had on the measured shear strength in the DSB test. Some ways of minimizing this interface frictional force were introduced in the paper. Given that the deformation approximates simple shear within the deforming zone across the sample centre (referred to as the shear zone), a method was proposed to evaluate the overall strains in the DSB test. The numerically simulated data were used to interpret, on a microscopic scale, the angle of internal friction and a 2D stressdilatancy equation for the mobilized plane in granular material. It was found that the angle of internal friction in granular material is not directly related to the interparticle friction angle (ϕµ). Instead, it relates to the average interparticle contact angle ([Formula: see text]) on the mobilized plane and the ratio k/f0, representing the degree of the probability distribution of the interparticle contact forces that is biased toward the positive zone of the contact angle θ (along the shear direction), where k is the slope of the linear distribution of the average interparticle contact forces against the interparticle contact angle; and f0is the average interparticle contact force.Key words: angle of internal friction, direct shear box test, distinct element method, friction, granular material, stressdilatancy.
The 2003 R.M. Hardy Lecture: Soil parameters for numerical analysis in clay
Authors: Graham J
Published: April 2006

Engineers in geotechnical practice work on increasingly complex problems with increasingly powerful numerical tools. Effective solutions to design problems need good information about the site and parameters (or functions) that describe how the soil will behave under the proposed loadings. These loadings can include heating, drying or wetting, time effects, and chemical changes as well as the more common structural loads. This paper outlines issues that need to be considered when laboratory tests are used to produce soil properties for use in numerical analyses. The focus is on soft to moderately stiff saturated clays. Similar considerations for in situ tests, stiff clays, and sands are not considered.Key words: clay, testing, characterization, properties, constitutive modeling.
Reliability analysis of the bearing capacity of a shallow foundation resting on cohesive soil
Authors: Sivakumar Babu G L , Srivastava Amit , Murthy D SN
Published: April 2006

In recent years, there have been considerable advances in the characterization of soil variability and its application in geotechnical designs. It is recognized that in using reliability-based design it is necessary to consider all sources of uncertainty in the analysis and incorporate them in the geotechnical design. It is also necessary to examine the reliability-based approach in relation to deterministic approaches. In this study, cone tip resistance (qc) data obtained from a static cone penetration test on a stiff clay deposit are analyzed by using random field theory; and statistical parameters, such as the mean, variance, and autocorrelation function, are estimated in evaluating the reliability of the allowable bearing capacity of a strip footing founded on the above deposit.Key words: reliability-based design, soil variability, random field, variance, autocorrelation function, bearing capacity.
Utilization of Atikokan coal fly ash in acid rock drainage control from Musselwhite Mine tailings
Authors: Wang H L , Shang J Q , Kovac V , Ho K S
Published: April 2006

A site-specific study is carried out to assess the suitability of utilizing Atikokan coal fly ash (AFA) as a buffering material to control and mitigate the generation of acid rock drainage from reactive Musselwhite Mine tailings. The physical, chemical, and mineralogical properties of the fly ash and mine tailings are determined via experiments, followed by six kinetic column permeation tests to monitor the leaching properties of the coal fly ash and coal fly ash  mine tailings mixtures. The results of the experiments indicate that the hydraulic conductivities of high-calcium AFA and the ashtailings mixtures are significantly reduced upon contact with acidic drainage. The pH of the pore fluid has increased from acidic (pH 4) to alkaline (pH 8 and above). Chemical analyses after the kinetic column permeation tests further indicate that concentrations of regulated elements in the leachate from the ashtailings mixtures are well below the guideline limits set by the Ontario environmental authority for accelerated flow conditions.Key words: coal fly ash, mine tailings, hydraulic conductivity, pH, heavy metals, acid rock drainage.
The interpretation of pendulum-type inclinometer readings
Authors: Lei G H , Ai Y B , Shi J Y
Published: April 2006

The conventional method of inclinometer data analysis computes the displacement components in two mutually orthogonal directions separately by using corresponding readings measured in individual directions. It is shown in this note that calculation errors, although insignificant, are induced when this method is used to interpret data measured by pendulum-type inclinometers, which are widely used as probe inclinometers in engineering practice. The inclinometer readings measured in the two directions are correlative, and they are dependent on both the angle of the inclinometer probe axis inclined to the gravity vertical and on the azimuth angle at which the probe movement direction deviates from one of the two directions. The displacement component in each direction can be interpreted more accurately by simultaneously using the tilt angles in both directions measured directly by the inclinometer probe. Relationships between the actual displacement components, the resultant displacement, the azimuth angle, and the tilt angles are derived and verified by laboratory experiments. A refined calculation procedure is proposed for interpreting the pendulum-type inclinometer readings, and the errors induced in the conventional method are analyzed.Key words: deformation, field instrumentation, ground movements, monitoring.
Granular protection design to minimize differential icing on insulated pavements
Authors: Côté Jean , Konrad Jean-Marie
Published: April 2006

The presence of an insulating layer in pavement structures generates a cooling effect at the surface. This can lead to slippery conditions on insulated pavement sections, while adjacent conventional pavement sections have dry surfaces. One way to control the occurrence of this phenomenon, known as differential icing, is to place a granular layer on top of the insulation. This paper proposes a rational design approach that considers climate conditions, as well as the properties of the pavement materials, to establish the minimum thickness of the granular protection layer needed to reduce the risk of differential icing. The proposed approach is illustrated with typical cases at various locations in Quebec, Canada. Design charts are developed to determine the minimum thickness of the granular protection layer as a function of the local mean annual air temperature, the thickness of the insulating layer, as well as the mineral content and the water content of the granular materials.Key words: insulated pavements, numerical modelling, climate, differential icing, granular protection.
Modelling of pipeline under differential frost heave considering post-peak reduction of uplift resistance in frozen soil
Authors: Hawlader Bipul C , Morgan Vincent , Clark Jack I
Published: April 2006

The interaction between buried chilled gas pipelines and the surrounding frozen soil subjected to differential frost heave displacements has been investigated. A simplified semi-analytical solution has been developed considering the post-peak reduction of uplift resistance in frozen soil as observed in laboratory tests. The nonlinear stressstrain behaviour of the pipeline at large strains has been incorporated in the analysis using an equivalent bending stiffness. The predicted results agree well with our finite element analysis and also with numerical predictions available in the literature, hence the simple semi-analytical solution can be considered as an alternative to numerical techniques. A parametric study has been carried out to identify the influence of key factors that can modify the uplift resistance in frozen soil. Among them, the residual uplift resistance has been found to be the important parameter for the development of stresses and strains in the pipeline.Key words: pipeline, frost heave, discontinuous permafrost, semi-analytical solution, uplift resistance, frozen soil.
Stability of D-shaped tunnels in a MohrCoulomb material under anisotropic stress conditions
Authors: Meguid M A , Rowe R K
Published: April 2006

The near-face stability of D-shaped tunnels excavated in a MohrCoulomb material subjected to anisotropic in situ stress conditions is investigated in the present study. The construction of the intake tunnel of the Darlington Nuclear Generating Station is analyzed using three-dimensional elasto-plastic finite element analysis. The induced displacement and stresses around the tunnel opening as the face advances are compared to the field measurements recorded during the tunnel excavation. The effect of rock mass strength reduction on the tunnel deformation, face stability, and distribution of stresses at the tunnel circumference is investigated for different in situ stress conditions. When the ratio of rock mass strength to overburden pressure falls below 0.5, excessive deformation occurrs and squeezing of the rock mass becomes a problem that can cause instability of both the tunnel circumference and the face.Key words: weak rock, tunnelling, horizontal stresses, three-dimensional, finite element, excavation, face stability.
Effect of specimen composition on the strength development in cemented paste backfill
Authors: Klein Katherine , Simon Dragana
Published: April 2006

This paper focuses on monitoring setting and strength development in cemented paste backfill (CPB). The composition of the paste is altered to study the effects of binder type and content, selected chemical admixtures (superplasticizers), mineral additives (e.g., fly ash), and pore fluid chemistry (e.g., ionic concentration and pH) on these properties. The three main techniques utilized are shear wave velocity measurements, penetration tests (e.g., Vicat needle tests), and unconfined compressive strength tests. All of these tests are sensitive to changes in the paste composition. The effect of the pore fluid chemistry and the chemical additives on the CPB properties depends on the ion type and concentration and the chemical composition of the superplasticizers. The shear wave velocity in both uncemented and cemented pastes increases with time as a result of self-weight consolidation, capillary forces, and cementation (the precipitation of ions in uncemented tailings pastes or cement hydration in cemented tailings pastes).Key words: cemented paste backfill, shear wave velocity, setting, unconfined compressive strength.
The effect of salinity on the freezing of coarse-grained sands
Authors: Arenson Lukas U , Sego Dave C
Published: April 2006

Unfrozen water is very important because it has a significant influence on the mechanical response of a frozen soil. It is particularly important to know if the water is available as free water or if it is bonded to the solid particles. A simple experimental setup was used to observe the freezing process of a coarse-grained soil under controlled freezing gradients and salinities. A fluorescent tracer helped to determine the location of the unfrozen water during freezing. Depending on the salinity and the thermal gradient, pockets of unfrozen water with a much higher salt concentration were trapped in pores under increased pore pressures. Even at salinities as low as 2 g/L, spicular ice crystals were identified with channels containing unfrozen water between the ice crystals. The experiments further indicate that the unfrozen water in coarse-grained frozen soils is in the middle of the pore space compared to the unfrozen water film that immediately surrounds fine-grained saline or non-saline soil particles.Key words: frozen soil, salinity, frost penetration, thermal conductivity.
Interpretation and modelling of deformation characteristics of a stiff North Sea clay
Authors: Jovičić Vojkan , Coop Matthew , Simpson Brian
Published: April 2006

An investigation into the behaviour of North Sea glaciomarine clays was carried out in which triaxial tests were conducted on both natural and reconstituted samples to assess the effects of structure. Although the tests were conventional CID tests, high quality instrumentation was used. The tests were also technically difficult both because of the very long test durations and because some of the samples were swelled back to very low effective stresses so that the effect of swelling on the influence of structure on the soil behaviour could be assessed. A "Class A" prediction of the behaviour in these tests was carried out using the BRICK model. Although the model is not designed to account for the influence of structure, it was found that its effects could be simulated by allowing the soil to have artificially high overconsolidation ratios (OCRs) so that the high undrained shear strengths resulting from structure could be modelled. Making the simple assumption that the decay of stiffness could be scaled from that of London Clay, reasonable predictions of the behaviour were made. The discrepancies between the predictions and the measured behaviour became significant only at the lowest stresses, where structure dominates the behaviour of the natural soil.Key words: laboratory testing, small strain stiffness, stiff clays, structure of soil, numerical predictions, shear deformation properties.
Characterization of a cemented sand with the pulse-velocity method
Authors: Khan Zahid , Majid Anwar , Cascante Giovanni , Hutchinson D Jean , Pezeshkpour Parsa
Published: April 2006

The effect of variation in cement content, initial water content, void ratio, and curing time on wave velocity (low-strain property) and unconfined compressive strength (large-strain property) of a cemented sand is examined in this paper. The measured pulse velocity is compared with predictions made using empirical and analytical models, which are mostly based on the published results of resonant column tests. All specimens are made by mixing silica sand and gypsum cement (2.520% by weight) and tested under atmospheric pressure. The wave velocity reaches a maximum at optimum water content, and it is mostly affected by the number of cemented contacts; whereas compressive strength is governed not only by the number of contacts but also by the strength of contacts. Experimental relationships are developed for wave velocity and unconfined compressive strength as functions of cement content and void ratio. Available empirical models underpredict the wave velocity (60% on average), likely because of the effect of microfractures induced by confinement during the testing. Wave velocity is found to be a good indicator of cement content and unconfined compressive strength for the conditions of this study.Key words: wave velocity, low-strain stiffness, cemented sands, elastic moduli, unconfined compressive strength.
Results from long-term measurement in piles of drag load and downdrag
Authors: Fellenius Bengt H
Published: April 2006

Several full-scale, long-term tests on instrumented piles performed since the 1960s and through the 1990s are presented. The results of the tests show that a large drag load will develop in piles installed in soft and loose soils. The test cases are from Norway, Sweden, Japan, Canada, Australia, United States, and Singapore and involve driven steel piles and precast concrete piles. The test results show that the transfer of load from the soil to the pile through negative skin friction, and from the pile back to the soil through positive shaft resistance, is governed by effective stress and that already a very small movement will result in mobilization of ultimate values of shaft shear. The pile toe resistance, on the other hand, is determined by downdrag of the pile and the resulting pile toe penetration. Reconsolidation after the pile installation with associated dissipation of pore pressures will result in significant drag load. An equilibrium of force in the pile will develop, where the sustained loads on the pile head and the drag load are equal to the positive shaft resistance plus the pile toe resistance. The location of the force equilibrium, the neutral plane, is also where the pile and the soil move equally. The drag load is of importance mostly for very long piles (longer than 100 pile diameters) for which the pile structural strength could be exceeded. Downdrag, i.e., settlement of the piled foundation, is a very important issue, however, particularly for low-capacity short piles. Soil settlement at the neutral plane will result in a downdrag of the pile. The magnitude of the downdrag will determine the magnitude of the pile toe penetration into the soil, which will determine the pile toe resistance and affect the location of the neutral plane. Nature's iteration of force and soil settlement will decide the final location of the neutral plane.Key words: piles, negative skin friction, drag load, downdrag, neutral plane, pile settlement.
Mesure de la déformabilité des sols in situ à l'aide d'un essai de chargement statique d'une pointe pénétrométrique
Authors: Arbaoui Hakim , Gourvès Roland , Bressolette Philippe , Bodé Laurent
Published: April 2006

The penetrometers allow one to obtain a global parameter, which is the cone resistance; this one is related to the soil failure and not to its deformability. The idea is to use a penetrometer to measure in situ the deformability properties of the soils. A new method of soil deformability measurement is then presented in this article: a monotonic static loading test using a penetrometer. The main objective is to measure particularly the three mechanical parameters, which are Young's modulus E, the cohesion c, and the friction angle ϕ. This article describes the testing equipment and the tests performed by precise procedure. An interpretation of the obtained monotonic experimental curves is also presented. It is based on a mathematical regression by three coefficients. According to this study, conducted on a purely frictional soil, the test allows one to obtain by a simple, fast, and economic way, a relevant evaluation of the soil deformability properties and its resistance. An axisymmetric finite element model of the experimental test is proposed to identify the correlation between the three mathematical coefficients of the experimental curve and the three rheological parameters E, c, and ϕ. The initial conditions before the test, which are crucial, are simulated by performing an unloadingreloading loop. Interesting results are obtained with this simplified, but realistic, finite element model. However, a simulation considering large strain conditions is still needed.Key words: penetrometer, deformability, monotonic static loading, deformation modulus, finite element simulation.
Rate-limited cation exchange in thin bentonitic barrier layers
Authors: Jo Ho Young , Benson Craig H , Edil Tuncer B
Published: April 2006

A three-compartment model was developed for simulating cation transport in bentonitic barrier layers that incorporates diffusion-controlled cation exchange among the mobile intergranular water (bulk pore water), immobile interparticle and interlayer water, and the montmorillonite mineral solid. Exchange on the external surfaces and interlayer region of montmorillonite is included. The model was evaluated for divalent-for-monovalent cation exchange in bentonite with experiments. A parametric study was conducted using the model to investigate factors affecting the time required to establish chemical equilibrium (i.e., completion of cation exchange) between the permeant liquid and thin layers of bentonite simulating geosynthetic clay liners (GCLs). Predictions obtained with the model were in general agreement with the data without calibration, except for Na concentrations in the effluent at very long times. Parametric simulations conducted with the model show that the time required to establish chemical equilibrium in GCLs is affected by the rate at which adsorbing cations are delivered to the pore space (affected by seepage velocity or influent concentration), the rate of mass transfer between the mobile and immobile liquid phases (controlled primarily by granule size of the bentonite), and the number of sites available for sorption (controlled by CEC and the dry density of the bentonite).Key words: bentonite, montmorillonite, exchange complex, diffusion, immobile liquid, interlayer.
A DATA RE-DISTRIBUTION LIBRARY FOR MULTI-PROCESSOR TASK PROGRAMMING
Authors: RAUBER THOMAS , RÜNGER GUDULA
Published: April 2006

Multiprocessor task (M-task) programming is a suitable parallel programming model for coding application problems with an inherent modular structure. An M-task can be executed on a group of processors of arbitrary size, concurrently to other M-tasks of the same application program. The data of a multiprocessor task program usually include composed data structures, like vectors or arrays. For distributed memory machines or cluster platforms, those composed data structures are distributed within one or more processor groups. Thus, a concise parallel programming model for M-tasks requires a standardized distributed data format for composed data structures. Additionally, functions for data re-distribution with respect to different data distributions and different processor group layouts are needed to glue program parts together. In this paper, we present a data re-distribution library which extends the M-task programming with Tlib, a library providing operations to split processor groups and to map M-tasks to processor groups.
ROUTING MULTIPLE WIDTH COMMUNICATIONS ON THE CIRCUIT SWITCHED TREE
Authors: ROY KRISHNENDU , VAIDYANATHAN RAMACHANDRAN , TRAHAN JERRY L.
Published: April 2006

Dynamically reconfigurable architectures offer extremely fast solutions to various problems. The Circuit Switched Tree (CST) is an important interconnect used to implement such architectures. A CST has a binary tree structure with processing elements (PEs) as leaves and switches as internal nodes. PEs communicate among themselves using the links of the tree. Key components for successful communication are scheduling individual communications and configuring the CST switches. This paper presents a scheduling and configuration algorithm for communications on a CST where conflicts necessitate multiple rounds of routing to perform all communications. The algorithm is distributed and requires only local information, yet it captures the global picture to ensure proper communication. The paper also explains how to apply the algorithm to an important class, "well-nested communications", for which the algorithm is optimal and efficient.
CRITICAL PATH SCHEDULING PARALLEL PROGRAMS ON AN UNBOUNDED NUMBER OF PROCESSORS
Authors: HAKEM MOURAD , BUTELLE FRANCK
Published: April 2006

In this paper we present an efficient algorithm for compile-time scheduling and clustering of parallel programs onto parallel processing systems with distributed memory, which is called The Dynamic Critical Path Scheduling DCPS. The DCPS is superior to several other algorithms from the literature in terms of computational complexity, processors consumption and solution quality. DCPS has a time complexity of O(e + v log v), as opposed to DSC algorithm O((e+v) log v) which is the best known algorithm. Experimental results demonstrate the superiority of DCPS over the DSC algorithm.
SCALABLE AND EFFICIENT IMPLEMENTATIONS OF THE LDPC DECODER USING RECONFIGURABLE MODELS
Authors: BABVEY SHARAREH , BOURGEOIS ANU G. , FERNÁNDEZ-ZEPEDA JOSÉ ALBERTO , MCLAUGHLIN STEVEN W.
Published: April 2006

In this paper we propose constant-time parallel algorithms for implementing the message-passing decoder of LDPC codes on a two dimensional R-Mesh and an LARPBS. The R-Mesh and LARPBS are dynamically reconfigurable models that provide hardware reuse and flexibility to problem changes. The same hardware can implement the decoder in both probability and logarithm domains over different channels. Moreover, to decode an alternate code, we may simply set up the required connections between the bit-nodes and check-nodes by modifying the initialization phase of the proposed algorithms. No extra wiring or hardware changes are required, as compared to other existing approaches. We illustrate that the R-Mesh and the LARPBS are efficient models for parallel implementation of the decoder in terms of time complexity, flexibility to problem changes and simplicity of routing messages. We also demonstrate that it is possible to optimally scale large block code sizes down to a smaller, available machine size if using an LR-Mesh or HVR-Mesh, two variants of the R-Mesh model.
SELF-STABILIZING ANONYMOUS LEADER ELECTION IN A TREE
Authors: XU ZHENYU , SRIMANI PRADIP K.
Published: April 2006

We propose a new self-stabilizing anonymous leader election algorithm in a tree graph. We show the correctness of the protocol and show that the protocol terminates in O(n4) time starting from any arbitrary initial state. The protocol can elect either a leaf node or a non leaf node (starting from the same initial state) depending on the behavior of the daemon. The protocol generalizes the result in [1] and at the same time is much simpler and terminates in polynomial number of moves.
PAMA: A FAST STRING MATCHING ALGORITHM
Authors: LU SHIYONG , CAO FENG , LU YI
Published: April 2006

String matching is a fundamental operation in computer science, and its performance has great impact on many applications including database query, text processing, DNA and protein sequence analysis. In this paper, we propose a fast string matching algorithm, PAMA (PAttern MAtching). The shift rule used by PAMA not only subsumes both the bad character rule and the good suffix rule employed by the well-known Boyer-Moore algorithm, but also employs an additional key observation to enable faster shifting during the string matching process. Theoretically, we prove that from the same alignment, the next shift of PAMA will be at least as much as that of the Boyer-Moore algorithm. Experimentally, we show that PAMA indeed significantly outperforms the original Boyer-Moore algorithm in almost all cases, and outperforms other Boyer-Moore variants such as Tuned-BM, Turbo-BM and Horspool for long patterns (length ≥ 128) or for small alphabets (size < 8).
INFIX-FREE REGULAR EXPRESSIONS AND LANGUAGES
Authors: HAN YO-SUB , WANG YAJUN , WOOD DERICK
Published: April 2006

We study infix-free regular languages. We observe the structural properties of finite-state automata for infix-free languages and develop a polynomial-time algorithm to determine infix-freeness of a regular language using state-pair graphs. We consider two cases: 1) A language is specified by a nondeterministic finite-state automaton and 2) a language is specified by a regular expression. Furthermore, we examine the prime infix-free decomposition of infix-free regular languages and design an algorithm for the infix-free primality test of an infix-free regular language. Moreover, we show that we can compute the prime infix-free decomposition in polynomial time. We also demonstrate that the prime infix-free decomposition is not unique.
DECIDABILITY OF THE SHAPE PRESERVING PROPERTY OF BOTTOM-UP TREE TRANSDUCERS
Authors: GAZDAG ZSOLT
Published: April 2006

It is a known result that both shape preserving top-down tree transducers and shape preserving bottom-up tree transducers are semantically equivalent to finite state relabeling tree transducers. Moreover, it is also known that the shape preserving property of top-down tree transducers is decidable. In this paper we present an analogous result for bottom-up tree transducers: we show that it is also decidable whether a bottom-up tree transducer is shape preserving or not.
THE SPANNING CONNECTIVITY OF THE (n,k)-STAR GRAPHS
Authors: HSU HONG-CHUN , LIN CHENG-KUAN , HUNG HUA-MIN , HSU LIH-HSING
Published: April 2006

A k-containerC(u, v) of a graph G is a set of k-disjoint paths joining u to v. A k-container C(u, v) is a k*-container if every vertex of G is incident with a path in C(u, v). A graph G is k*-connected if there exists a k*-container between any two distinct vertices u and v. A k-regular graph G is super spanning connected if G is i*-connected for all 1 ≤ i ≤ k. In this paper, we prove that the (n, k)-star graph Sn,k is super spanning connected if n ≥ 3 and (n-k) ≥ 2.
TRANSITIVITY IN TWO-DIMENSIONAL LOCAL LANGUAGES DEFINED BY DOT SYSTEMS
Authors: JONOSKA NATAŠA , PIRNOT JONI BURNETTE
Published: April 2006

The paper investigates two-dimensional recognizable languages that are defined by the so-called "dot systems" that are special subgroups of (ℤ/2ℤ)ℤ2. The dot shapes that provide directional transitivity or mixing for the related language are investigated. It is shown that languages defined by parallelogram shapes fail to be transitive in the direction of a defining vector and hence fail to be mixing, while certain triangular shapes guarantee that the factor language of the associated dot system will be mixing. Dot systems belong to a class of two-dimensional shift spaces that have a factor language such that every admissable block can be extended to a configuration of the entire plane. For this class of shift spaces we introduce a finite graph (i.e., a finite state automaton) that recognizes two-dimensional local languages, then show that certain transitivity properties may be observed from the structure of the finite graph.
THE BASE PROBLEM FOR D0L PARIKH SETS
Authors: HONKALA JUHA
Published: April 2006

We give a method to decide whether or not a given D0L Parikh set can be recognized in some base. In the positive case the bases can be computed effectively.
COVERS FROM TEMPLATES
Authors: EHRENFEUCHT A. , ROZENBERG G.
Published: April 2006

We study the problem of covering a word f by a set F of available segments. In particular we demonstrate that each F induces a unique structure (scaffold) on f which determines how all "succint" coverings of f (by elements of F) are positioned on f. Our motivation for this study comes from the formalization of the template–guided recombination which is a molecular operation that provides a solution for a molecular implementation of gene assembly in ciliates.
Electrochemical Incorporation of Nitrogen into a Zirconia Solid Electrolyte
Authors: Valov I. , Korte C. , De Souza R. A. , Martin M. , Janek J.
Published: April 2006

The electrochemical reactivity of molecular nitrogen is demonstrated by incorporation into yttria stabilized zirconia (YSZ) solid electrolyte upon cathodic polarisation at an intermediate temperature of about

700
°
C

. The nitrogen doping/incorporation (nitridation of YSZ) can be spatially controlled, as it only occurs in the vicinity of the electrode. The influence of the electrode material and the dopant (yttria) concentration is discussed. The

I
-
E

characteristics suggests a complex process

(

N

2

+
6

e
−

=
2

N

3
−

)

proceeding via a sequence of reaction steps. The electrochemical nitrogen doping is proven by secondary ion mass spectrometry.
Singularly perturbed periodic parabolic equations with alternating boundary layer type solutions
Authors: Vasil′eva Adelaida B. , Kalachev Leonid V.
Published: April 2006

We consider a class of singularly perturbed parabolic equations
for which the degenerate equations obtained by setting the small
parameter equal to zero are algebraic equations that have several
roots. We study boundary layer type solutions that, as time
increases, periodically go through two fairly long lasting stages
with extremely fast transitions in between. During one of these
stages the solution outside the boundary layer is close to one of
the roots of the degenerate (reduced) equation, while during the
other stage the solution is close to the other root. Such
equations may be used as models for bio‐switches where the
transitions between various stationary states of biological
systems are initiated by comparatively slow changes within the
systems.
Synthetic, Structural, and Biochemical Studies of Organotin(IV) with Schiff Bases Having Nitrogen and Sulphur Donor Ligands
Authors: Singh Har Lal , Varshney A. K.
Published: April 2006

Three bidentate Schiff bases having nitrogen and sulphur donor
sequences were prepared by condensing
S‐benzyldithiocarbazate (NH2NHCS2CH2C6H5) with heterocyclic aldehydes. The reaction of diphenyltin dichloride
with Schiff bases leads to the formation of a new series of
organotin(IV) complexes. An attempt has been made to prove their
structures on the basis of elemental analyses, conductance
measurements, molecular weights determinations, UV, infrared, and
multinuclear magnetic resonance (H1, C13, and S119n) spectral studies. Organotin(IV) complexes were
five‐ and six‐coordinate. Schiff bases and their corresponding
organotin complexes have also been screened for their
antibacterial and antifungal activities and found to be quite
active in this respect.
Convergence and stability of a three-step iterative algorithm for a general quasi-variational inequality problem
Authors: Kazmi KR , Bhat MI
Published: April 2006

We consider a general quasi-variational inequality problem involving nonlinear, nonconvex and nondifferentiable term in uniformly smooth Banach space. Using retraction mapping and fixed point method, we study the existence of solution of general quasi-variational inequality problem and discuss the convergence analysis and stability of a three-step iterative algorithm for general quasi-variational inequality problem. The theorems presented in this paper generalize, improve, and unify many previously known results in the literature.