Different Degrees Of Refinement Research Articles

Assessment and strengthening of reinforced concrete bridges with half‐joint deterioration

AbstractExisting Niagara‐type concrete cantilever bridges, which in Italy are called Gerber bridges, suffer from degradation due to reinforcement corrosion and a consequent reduced load‐bearing capacity. The assessment of these structures is therefore an important part of the procedures for analyzing the state of existing bridges and any interventions required for their retrofitting. In particular, safety against failure of the half‐joint must be evaluated with respect to the behavior of the entire bridge and its state of conservation, determining what the conditions are that lead to failure, in terms of loads, state of stress, and possibly cracking state. This evaluation has to be carried out considering the configuration of the bridge through local and global models, in the presence of the crossbeam between the main girders or the prestressing tendons that can modify the behavior of the Gerber saddle, compared to that expected for a simple dapped‐end beam. To do this, it is necessary to combine the in situ investigations with reliable analytical and numerical models, which can correctly interpret the structural behavior of the bridge, determining the critical aspects for safety. The approach followed in this study was to combine the strut‐and‐tie models with nonlinear finite element models that can provide reliable information to the engineer who deals with the assessment and subsequently the conception of rehabilitation, in combination with in situ investigations and material tests. This was carried out through two different case studies in which the shape of the Gerber saddle, the presence of the crossbeam, and the presence of prestressing characterize the behavior and highlight the degree of safety and that of structural robustness. The results of the analyses carried out show that the presence of prestressing and a careful design with the use of large amounts of reinforcement can lead in some cases to high safety factors and consequently to a good level of robustness. They also show that the structural behavior can vary significantly according to the level of reinforcement corrosion: this is an aspect that can only be correctly assessed with the use of different models with different degrees of refinement. Finally, a proposal for global structural rehabilitation is presented by closing saddles, changing the static scheme to the continuous beam, and supplying external prestressing to strengthen the deck.

Influence of refractive index accurate model of supersonic vehicle window flow field on aero-optical characteristics

Aircraft with a supersonic speed has a complex flow field around its optical window. The precise modeling of the refractive index of the flow field is of great significance for the research of optical homing, laser guided and optical remote sensing. However, in practice, It difficult to obtain a refined refractive index model because of the sparse sampling points distribution near the optical window. The density flow field was converted into the refractive index field using the Gladstone-Dale relation. The obtained refractive index field data was inputted into the back propagation neural network to find the refractive index field distributions with different degrees of refinement. The results of aero-optical effects of supersonic aircraft using back propagation neural network combined with ray tracing method show that: flight height and angle of incidence are important indicators that affect aero-optical effects. Meanwhile, the refined refractive index field has a very important effect on the parameters of aerodynamics such as imaging displacement, deflection angle, optical path difference. But there is little effect on the Strehl ratio. The use of back propagation neural network algorithm to accurately obtain the refractive index will greatly ensure the accuracy of aerodynamic optical results.

Emulsifying properties of lentil protein preparations obtained by dry fractionation

Dry fractionated legume protein ingredients are gaining attention as alternatives to conventional solvent extracted legume proteins, being more resource efficient and often exhibiting novel functional properties. However, lack of knowledge about the relationship between composition and functionality limit a more wide-spread use of dry-fractionated legume protein in applications. In this study, lentil fractions of different degrees of refinement were prepared using air classification having protein and starch contents of 16–59% and 4–64%, respectively. The dry fractionated lentil fractions could emulsify and stabilize 10 wt% oil-in-water emulsions, while a conventional lentil protein isolate used for comparison was not able to form stable emulsions. The latter had significantly larger mean droplet diameters (around 20 µm) due to droplet flocculation than emulsions made with the different lentil fractions ranging between 0.3 and 5.5 µm. Similar surface charges (between −22 and −31 mV) indicated that the discrepancy could be ascribed to differences in steric repulsion and mechanical strength of the interfacial layers between conventionally and dry fractionated lentil. Storage stability tests of emulsions stabilized with dry fractionated samples resulted in separation into a low and higher density phase with the individual droplets being stable against coalescence in both phases. The phase separation was attributed to gravimetrical sedimentation of larger insoluble components accumulating in the denser phase, which was impacted by the degree of refinement by air classification. The results highlight the potential of dry fractionation for the production of sustainable ingredients with unique composition and functionality.

Optimizing lignocellulosic nanofibril dimensions and morphology by mechanical refining for enhanced adhesion

Using lignocellulosic nanofibrils as adhesive binders in structural composites is a growing field of interest attributable to their renewability, recyclability, and strength. A fundamental understanding of their adhesion mechanisms is crucial to tailor performance and optimize production costs. These mechanisms were elucidated by studying the morphology dependent adhesion in a model system composed of cellulose nanofibrils (CNFs) at different degrees of refinement and porous paper substrates. CNFs and lignin containing cellulose nanofibrils (LCNF) were characterized at different length scales using optical, atomic force, and scanning electron microscopy, revealing a complex distribution of sizes, spanning the macroscale to the nanoscale, which are modified unequally by refinement. Strong adhesion was correlated to a decrease in fiber size on the largest length scale and with an increase in relative fibril surface area. Flocculation hampered effective LCNF adhesion, but adding suspension stabilizers improved adhesion to levels comparable to CNF.

Refining the Paradigm of Sketching in AI-Based Level Design

This paper describes computational processes which can simulate how human designers sketch and then iteratively refine their work. The paper uses the concept of a map sketch as an initial, low-resolution and low-fidelity prototype of a game level, and suggests how such map sketches can be refined computationally. Different case studies with map sketches of different genres showcase how refinement can be achieved via increasing the resolution of the game level, increasing the fidelity of the function which evaluates it, or a combination of the two. While these case studies use genetic algorithms to automatically generate levels at different degrees of refinement, the general method described in this paper can be used with most procedural generation methods, as well as for AI-assisted design alongside a human creator.

Parametrized classifiers for optimal EFT sensitivity

We study unbinned multivariate analysis techniques, based on Statistical Learning, for indirect new physics searches at the LHC in the Effective Field Theory framework. We focus in particular on high-energy ZW production with fully leptonic decays, modeled at different degrees of refinement up to NLO in QCD. We show that a considerable gain in sensitivity is possible compared with current projections based on binned analyses. As expected, the gain is particularly significant for those operators that display a complex pattern of interference with the Standard Model amplitude. The most effective method is found to be the “Quadratic Classifier” approach, an improvement of the standard Statistical Learning classifier where the quadratic dependence of the differential cross section on the EFT Wilson coefficients is built-in and incorporated in the loss function. We argue that the Quadratic Classifier performances are nearly statistically optimal, based on a rigorous notion of optimality that we can establish for an approximate analytic description of the ZW process.

A Coarse-to-Fine Network for Ship Detection in Optical Remote Sensing Images

With the increasing resolution of optical remote sensing images, ship detection in optical remote sensing images has attracted a lot of research interests. The current ship detection methods usually adopt the coarse-to-fine detection strategy, which firstly extracts low-level and manual features, and then performs multi-step training. Inadequacies of this strategy are that it would produce complex calculation, false detection on land and difficulty in detecting the small size ship. Aiming at these problems, a sea-land separation algorithm that combines gradient information and gray information is applied to avoid false alarms on land, the feature pyramid network (FPN) is used to achieve small ship detection, and a multi-scale detection strategy is proposed to achieve ship detection with different degrees of refinement. Then the feature extraction structure is adopted to fuse different hierarchical features to improve the representation ability of features. Finally, we propose a new coarse-to-fine ship detection network (CF-SDN) that directly achieves an end-to-end mapping from image pixels to bounding boxes with confidences. A coarse-to-fine detection strategy is applied to improve the classification ability of the network. Experimental results on optical remote sensing image set indicate that the proposed method outperforms the other excellent detection algorithms and achieves good detection performance on images including some small-sized ships and dense ships near the port.

Qualified Geometric Stiffness for Linear Buckling and Second-Order Nonlinear Analysis of Framed Structures

There exist various potential energy formulations dealing with the linear buckling and second-order nonlinear analysis of framed structures with different degrees of refinement in the kinematic model. However, the geometric stiffnesses derived often give rise to different structural behaviors, which indeed represents a confusion regarding their qualified usage in bifurcation and post-buckling analysis. This study aims to carry out a comprehensive evaluation of the validity of the geometric stiffness for use at the predictor and corrector phrases of an incremental analysis based on the rigid-body motion test. To remove the unbalanced element forces caused by the nonqualified geometric stiffness, a supplementary correction matrix is developed according to simple kinematic and static analysis in the context of rigid rotations. An updated Lagrangian approach-based force recovery procedure (FRP) is presented for updating the element forces with improved reliability and efficiency, when using relatively large step size. Some benchmark problems which exhibit compound three-dimensional nonlinear behavior of framed structures are solved to clarify the capabilities of rigid-body qualified and nonqualified geometric stiffnesses along with the existing FRPs for different mesh sizes, step sizes and load patterns. It is shown that the proposed procedure can be adopted to predict correct buckling loads and post-buckling equilibrium paths without adding extra computational costs.

Comparing the ISBA and J2000 approaches for surface flows modelling at the local scale in the Everest region

This paper compares the hydrological responses at the local scale of two models using different degrees of refinement to represent physical processes in sparsely instrumented mountainous Himalayan catchments. This work presents the novelty of applying, at a small spatio-temporal scale and under the same forcing conditions, a fully distributed surface scheme based on mass and energy balance equations (ISBA surface scheme), and a semi-distributed calibrated model (J2000 hydrological model). A new conceptual module coupled to the ISBA surface scheme for flow routing is presented. Two small catchments located in mid- and high- mountain environments were chosen to represent the very different climatic and physiographic characteristics of the Central Himalayas in the Everest region of eastern Nepal. The results show that both models globally represent the dynamic of the processes for evaporation, quick runoff and discharge in a similar way. The differences in the model structures and results mainly concern the snow processes and the soil processes. In particular for the high-mountain catchment, the snow-pack simulation is shown to be the main driver of the discrepancy between the two models. The sub-daily variations of snow processes are shown to significantly influence the estimation of the snow-melt contribution to discharge.

Dicent Symbols in Non-Human Semiotic Processes

Against the view that symbol-based semiosis is a human cognitive uniqueness, we have argued that non-human primates such as African vervet monkeys possess symbolic competence, as formally defined by Charles S. Peirce. Here I develop this argument by showing that the equivocal role ascribed to symbols by “folk semiotics” stems from an incomplete application of the Peircean logical framework for the classification of signs, which describes three kinds of symbols: rheme, dicent and argument. In an attempt to advance in the classifying semiotic processes, Peirce proposed several typologies, with different degrees of refinement. Around 1903, he developed a division into ten classes. According to this typology, symbols can be further analysed in three subclasses (rheme, dicent, argument). I proceed to demonstrate that vervet monkeys employ dicent symbols. There are remarkable implications of this argument since ‘symbolic species theory’ fails to explore the vast Peircean semiotic philosophy to frame questions regarding the emergence and evolution of symbolic processes.

ELDAMeth: An agent-oriented methodology for simulation-based prototyping of distributed agent systems

In application domains, such as distributed information retrieval, content management and distribution, e-Commerce, the agent-based computing paradigm has been demonstrated to be effective for the analysis, design and implementation of distributed software systems. In particular, several agent-oriented methodologies, incorporating suitable agent models, frameworks and tools, have been to date defined to support the development lifecycle of distributed agent systems (DAS). However, few of them provide effective validation methods to analyze design objects at different degrees of refinement before their actual implementation and deployment. In this paper, ELDAMeth, a simulation-based methodology for DAS, which enables rapid prototyping based on visual programming, validation, and automatic code generation for JADE-based DAS, is presented. ELDAMeth can be used both stand-alone for the modeling and evaluation of DAS and coupled with other agent-oriented methodologies for enhancing them with simulation-based validation. In particular, the proposed methodology, which is based on the ELDA (Event-driven Lightweight Distilled StateCharts-based Agents) agent model, provides key programming abstractions (event-driven computation, multi-coordination, and coarse-grained strong mobility) very suitable for highly dynamic distributed computing and is supported by a CASE tool-driven iterative process seamlessly covering the detailed design, simulation, and implementation phases of DAS. A simple yet effective case study in the distributed information retrieval domain is used to illustrate the proposed methodology.

Determination of Three-Dimensional Solubility Parameters and Solubility Spheres for Naphthenic Mineral Oils

The Hansen solubility parameters were determined for three hydrocarbon fluids, equivalent to naphthenic mineral oil of different degrees of refinement. This was done by an indirect method based on the solubility of the hydrocarbon fluids in a system of solvents with known Hansen solubility parameters. It was concluded that the method may serve as a tool to estimate the approximate solubility parameters of naphthenic oil. However, in this study, the accuracy was insufficient to separate naphthenic oil of different degrees of refinement.

Adhesive wear in deep drawing of aluminum sheets

This paper focuses on the experimental validation of the common model for adhesive wear initiation by Czichos et al. for conventional aluminum deep drawing operations. A strip drawing test with a 90° bending process is used for the studies. The local contact conditions at the drawing edge are examined by analytical examination and numerical simulation on different degrees of refinement. Contact normal stresses and temperature profiles are investigated and correlated with the experimental observation of adhesive wear.

Comparison of keyhole and conventional gas tungsten arc welds in commercially pure titanium

Keyhole gas tungsten arc welding (GTAW), a novel process recently developed at CSIRO Manufacturing Science and Technology, Australia, has been used to join commercially pure (CP) titanium. The process enables single pass, out of chamber welding of 12.7 mm thick CP titanium without expensive filler metal addition or joint preparation. The microstructure and mechanical properties of the resultant weld joint have been compared with those of a multipass conventional GTAW joint in CP titanium prepared from plates of the same thickness with a double-V edge preparation and the addition of a matching filler metal. It was shown that the differences in the net heat input and weld thermal cycles associated with the two processes led to similar microstructures, albeit of different degrees of refinement. As a result, the tensile and hardness properties of the two welded joints were similar to each other and comparable to those of the base material. The acicular nature of the fusion zone microstructure in both welds led to a significant increase in their notch toughness over that of the base material. It is concluded that the keyhole GTAW, with its significantly higher productivity combined with the simplicity of proven technology and low capital investment requirements, can be successfully applied in the welding of heavy section CP titanium, without sacrificing the metallurgical quality associated with the GTAW process.

Electron transmission across an interface of different one-dimensional crystals.

An exact solution is obtained for the quantum-mechanical reflection and transmission coefficients for the electronic motion across the boundary of two different one-dimensional crystals, each described by a Kronig-Penney model. The result is compared with those obtained in the envelope-function (plane-wave) approximations with different degrees of refinement. It turns out that, in general, neither the simplest such approximation, corresponding to a continuous envelope function \ensuremath{\Phi} and a discontinuous gradient \ensuremath{\Phi}' (with a single-parameter matching of the electron flux ${m}^{\mathrm{\ensuremath{-}}1}$\ensuremath{\Phi}' across the interface), nor the refined procedure, originally proposed by Harrison (corresponding to a two-parameter matching of discontinuous \ensuremath{\Phi} and \ensuremath{\Phi}' subject to the flux-continuity condition), produce an adequate description. Only with a special assumption about the size of the crystal cell at the interface do these procedures provide a consistent approximation; for this case we have derived an explicit expression for the matching coefficients in terms of ``crystal'' structure parameters. For arbitrary sizes of the boundary cell, the exact solution for the reflection coefficient in the vicinity of the band edges can be modeled with a three-parameter envelope-function approximation.

Error analysis in semiconductor impurity energy level determinations

Computer analysis is presented of the neutrality expression for a semiconductor such as Ge or Si with a typical donor impurity. The anticipated errors in impurity energy-level determination are thereby demonstrated for different degrees of refinement in common graphical techniques involving Hall or conductivity measurements as a function of temperature. It is shown that the graphical technique may be optimized to either the region where the activation energy is equal to the complete ionization energy or half the ionization energy, but not both. This is accomplished by taking proper cognizance of the temperature dependence in the effective density of states function. Graphical technique not properly optimized to the region may result in errors as much as 20 percent. It is also shown that conductivity plots can be quite accurate through use of a graphical method which properly takes under consideration the temperature dependence in the effective density of states function and the carrier mobility. Hall and conductivity data taken from a gold doped germanium sample are presented to illustrate the nature of the problem and the errors involved.

Influence of welding procedure on stress-rei ief cracking in Cr–Mo–V steels: Part 1 use of cross-weld specimens

Rupture tests at the stress-relieving temperature have been made on specimens cut transversely from welds in a Cr–Mo–V steel known to be very susceptible to stress-relief cracking. The welds have been made by the manual metal-arc process and various weld procedures used to achieve different degrees of refinement in the weld heat-affected zones. Failure generally occurs in the weld heat-affected zones and the strengths and mean deformation to rupture are a function of the welding procedure. Rupture strengths are compared with those obtained in earlier work from thermally simulated specimens and the mean rupture deformations are compared with the relaxation strain expected in large welds during stress relief. The relevance of these results to stress-relief cracking and the repair of crack-prone steels in power station plant is discussed.