A novel approach for characterizing frozen soil damage based on mesostructure

2021 ◽  
pp. 105678952110454
Author(s):  
Shijie Chen ◽  
Wei Ma ◽  
Guoyu Li
Keyword(s):  
Structural Damage ◽  
Inflection Point ◽  
Mechanical Response ◽  
Frozen Soil ◽  
Strengthening Effect ◽  
Ct Number ◽  
Novel Approach ◽  
Initial Stage ◽  
Expansion Curve ◽  
Starting Point

In this study, the relationship between the computed tomography (CT) number and the density of frozen soil was established on a macro and mesoscopic scale, aimed at overcoming the shortcomings of the mesoscopic damage behavior predicted by previous macroscopic research on frozen soil. In addition, considering the influence of stress level and temperature, a mesoscopic structural damage variable was proposed, which could reflect the damage characteristics of frozen soil. On this basis, combining the meso-damage of frozen soil with the macro-mechanical response, the mechanism of the damage evolution of frozen soil under stress was studied. It was found that the variation law of porosity was consistent with the law of the mesoscopic damage expansion in frozen soil. In the initial stage of stress loading, compaction was observed before meso-crack expansion. The internal structure exhibited a strengthening effect, by which the damage was reduced. The macroscopic mechanical properties were characterized by an elastic strain phase. As the stress continued to increase, an inflection point of the damage value appeared, and the damage gradually increased. The starting point of the meso-fracture expansion curve could represent the stress yield point on the macroscopic mechanical curve, and also represented the inflection point of the volume change of the material from the contraction to the dilatancy. When the damage value was gradually increased and became equal to the initial value, the deviatoric stress reached the peak of the macroscopic mechanical curve.

scholarly journals A Random Forest Model for the Prediction of FOG Content in Inlet Wastewater from Urban WWTPs

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1237
Author(s):  
Vanesa Mateo Pérez ◽  
José Manuel Mesa Fernández ◽  
Joaquín Villanueva Balsera ◽  
Cristina Alonso Álvarez
Keyword(s):  
Random Forest ◽  
Wastewater Treatment Plants ◽  
Learning Algorithm ◽  
Global Improvement ◽  
Treatment Processes ◽  
Early Adoption ◽  
Novel Approach ◽  
Number Of Factors ◽  
Initial Stage ◽  
Correct Design

The content of fats, oils, and greases (FOG) in wastewater, as a result of food preparation, both in homes and in different commercial and industrial activities, is a growing problem. In addition to the blockages generated in the sanitary networks, it also represents a difficulty for the performance of wastewater treatment plants (WWTP), increasing energy and maintenance costs and worsening the performance of downstream treatment processes. The pretreatment stage of these facilities is responsible for removing most of the FOG to avoid these problems. However, so far, optimization has been limited to the correct design and initial installation dimensioning. Proper management of this initial stage is left to the experience of the operators to adjust the process when changes occur in the characteristics of the wastewater inlet. The main difficulty is the large number of factors influencing these changes. In this work, a prediction model of the FOG content in the inlet water is presented. The model is capable of correctly predicting 98.45% of the cases in training and 72.73% in testing, with a relative error of 10%. It was developed using random forest (RF) and the good results obtained (R2 = 0.9348 and RMSE = 0.089 in test) will make it possible to improve operations in this initial stage. The good features of this machine learning algorithm had not been used, so far, in the modeling of pretreatment parameters. This novel approach will result in a global improvement in the performance of this type of facility allowing early adoption of adjustments to the pretreatment process to remove the maximum amount of FOG.

Baatɔnu Personal Names from Birth to Death

Africa ◽  
2000 ◽  
Vol 70 (1) ◽  
pp. 79-106 ◽  
Author(s):  
Wendy Schottman
Keyword(s):  
Family Relations ◽  
Personal Names ◽  
Initial Stage ◽  
Starting Point

AbstractThe circumstances of a child’s birth define his or her starting point in life, and they will be inscribed in the child’s file, so to speak, by means of a set of rule-governed birth names. These ‘child names’ are perfectly suitable for this initial stage of life, but all Baatɔmbu aspire one day to replace this original set of ‘orthodox’ names by another orthodox name, an inherited title name, corresponding to an achieved social and spiritual status. Commoners and nobles have separate institutions of gɔɔbiru, ‘inherited title names’, but in both cases the successive bearers of a gɔɔbiru share an exemplary essence that each must honour and perpetuate with his life. Baatɔnu nobles bestow baptism names on children around the age of seven, allowing these young candidates for the various gɔɔbiru to be matched, according to their potential, with a name whose influence will guide them into adulthood. Joking names and teknonyms can be classified as non-orthodox or informal names and seem to fill a gap left by the orthodox names, allowing personal and family relations to be expressed and negotiated. These names carry no prestige, but their use affords pride and pleasure and, unlike orthodox names, they can be used without infringing ‘shame’-based taboos.

scholarly journals Constitutive Description of Extra Strengthening in Gradient Nanotwinned Metals

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2375
Author(s):  
Wufan Chen ◽  
Panpan Wan ◽  
Qingkun Zhao ◽  
Haofei Zhou
Keyword(s):  
Constitutive Model ◽  
Structural Design ◽  
Work Hardening ◽  
Mechanical Response ◽  
Theoretical Framework ◽  
Deformation Mechanisms ◽  
Strengthening Effect ◽  
Metallic Materials ◽  
Engineering Applications ◽  
Increased Strength

Gradient nanotwinned (GNT) metals exhibit extra strengthening and work hardening behaviors, which endow them impressive potentials in engineering applications. The increased strength is attributed to the dense interactions between dislocations and boundaries in the grain interiors. However, a constitutive model elucidating the extra strengthening effect is currently lacking. Here, we propose a theoretical framework to describe the mechanical response of GNT metals, especially the unusual extra strengthening behavior. The model captures the deformation mechanisms of GNT metals and coincides well with the reported experiment. The constitutive description developed in this work presents a tool to guide the structural design for developing gradient metallic materials.

scholarly journals Conjugated structure of the lawn-grass cover of the urban landscape

2020 ◽  
Vol 10 (212) ◽  
pp. 68-72
Author(s):  
Mikhail Motyl ◽  
◽  
Alexander Romanyuk ◽  
Vladimir Titok
Keyword(s):  
Urban Landscape ◽  
Green Spaces ◽  
Ecological Niches ◽  
Grass Cover ◽  
Urban Green ◽  
Urban Green Spaces ◽  
Native Flora ◽  
Initial Stage ◽  
Unique Object ◽  
Starting Point

The features of the conjugated structure of plants of the lawn-grass cover of the city of Minsk as an unique object of a natural-anthropogenic landscape and a phyto-indicator of the current state of urban green spaces of Belarus are established. The basic composition of 35 species of native flora, which form 10 conjugated groups and reflect diversity of ecological niches, is determined. Their composition and the nature of the bonds indicate a tendency toward xerophytization of the soil cover. The data obtained reflect the initial stage of its transformation and can serve as a starting point for monitoring climate and anthropogenic changes in the structure of urban green spaces.

scholarly journals Re-Constructing the Choreographic Studio of João Fiadeiro Through Animated Infographic Films

1969 ◽  
Vol 1 (1) ◽  
Author(s):  
Stephan Jürgens
Keyword(s):  
Academic Research ◽  
Contemporary Dance ◽  
Interesting Point ◽  
Creative Processes ◽  
Artistic Process ◽  
Conceptual Structures ◽  
Novel Approach ◽  
Starting Point ◽  
Interdisciplinary Arts

The starting point for this article is an artist-led practice developed by choreographer João Fiadeiro during the past two decades, which has been designated as "Composition in Real Time" (CTR). The interesting point about this methodology is that it has been applied in performance composition and in arts education by its author himself; but also in such diverse fields as anthropology, sociology, neurosciences, and economy by scientists and academics in collaboration with Fiadeiro. The authors of this article have conducted a long-lasting case study on the artistic process of Fiadeiro in the framework of an ERC-funded interdisciplinary arts and cognition project. We present our resulting novel approach to researching contemporary dance work through the creation and production of animated infographic films. Along with leading PaR theorists we argue that the utilization of adequate artistic techniques and methods in academic research can successfully reveal how unique creative ideas and conceptual structures come into being in the creative processes of today's contemporary artists. The article discusses specific excerpts of the provided animated infographic films to show how we digitally re-constructed Fiadeiro’s conceptual and imaginative universe, and how our findings can address both an academic and interested lay audience. SOLOS study: I am sitting in a different room you are in now from BlackBox Art&Cognition on Vimeo. SOLOS study: I was here from BlackBox Art&Cognition on Vimeo. Graphic models developed by João Fiadeiro from BlackBox Art&Cognition on Vimeo.

A Micro-Architectural Based Structural Model for Elastomeric Electrospun Scaffolds

2010 ◽  
Author(s):  
Antonio D’Amore ◽  
John A. Stella ◽  
David E. Schmidt ◽  
William R. Wagner ◽  
Michael S. Sacks
Keyword(s):  
Tissue Engineering ◽  
Structural Model ◽  
Mechanical Response ◽  
Multiple Scales ◽  
Sem Images ◽  
Form Complex ◽  
Novel Approach ◽  
Structural Deformations ◽  
Mechanical Models ◽  
Specific Tissue

Interest in electrospun polymeric nano-microfibers for tissue engineering applications has rapidly grown during the last decade. In spite of this technique’s flexibility and ability to form complex fiber assemblies, additional studies are required to elucidate how the fibrous microstructure translates into specific tissue (or meso-scale) level mechanical behavior. Deterministic structural models can quantify how key structures contribute to the mechanical response as a function of bulk deformation across multiple scales, as well as provide a better understanding of cellular mechanical response to local micro-structural deformations. Our ultimate aim is to utilize such models to assist tissue engineering scaffold design. In the current work, we present a novel approach to automatically quantify key micro-architectural descriptors (fiber overlaps, connectivity, orientation, and diameter) from SEM images of electrospun poly (ester urethane) urea (PEUU) to recreate statistically equivalent scaffold mechanical models. An appropriate representative volume element (RVE) size was determined by quantifying the point of stabilization of the architectural descriptors over image areas of increasing size. Material models were then generated specifying: fiber overlap density, fiber orientation, connectivity and fiber diameter. Macro-meso mechanical response was predicted via FEM simulations.

Phenomenological and Structural Aspects of the Mechanical Response of Arteries

2000 ◽  
Author(s):  
Ray W. Ogden ◽  
Christian A. J. Schulze-Bauer
Keyword(s):  
Residual Stresses ◽  
Mechanical Response ◽  
Physiological State ◽  
Circumferential Stress ◽  
Morphological Structure ◽  
Cylindrical Tube ◽  
Single Layer ◽  
Theory Of Elasticity ◽  
Starting Point ◽  
Circular Cylindrical Tube

Abstract In this paper we present some new data from extension-inflation tests on a human iliac artery and then, on the basis of the nonlinear theory of elasticity, we examine a possible model to represent this data. The model considers the artery initially as a thick-walled circular cylindrical tube which may consist of two or more concentric layers. In order to take some account of the architecture (morphological structure), each layer of the material is regarded as consisting of two families of mechanically equivalent helical fibers symmetrically disposed with respect to the cylinder axis. The resulting material properties are then orthotropic in each layer. General formulas for the pressure and the axial load in the symmetric inflation of an extended tube are obtained. The starting point is the unloaded circular cylindrical configuration, but (in general unknown) residual stresses are included in the formulation. The model is illustrated by specializing firstly to the case of a single layer so that the consequences of the hypothesis of uniform circumferential stress in the physiological state can be examined theoretically. This enables the required residual stresses to be calculated explicitly. Secondly, the equations are specialized for the membrane approximation in order to show how certain important characteristics of the experimental data can be replicated using a relatively simple anisotropic membrane model.

scholarly journals On the Effects of Structural Coupling on Piezoelectric Energy Harvesting Systems Subject to Random Base Excitation

Aerospace ◽  
2020 ◽  
Vol 7 (7) ◽  
pp. 93
Author(s):  
Hamidreza Masoumi ◽  
Hamid Moeenfard ◽  
Hamed Haddad Khodaparast ◽  
Michael I. Friswell
Keyword(s):  
Energy Harvesting ◽  
Mechanical Response ◽  
Harmonic Excitation ◽  
Point Of View ◽  
Analytical Models ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Novel Approach ◽  
Band Limited ◽  
Multi Body

The current research investigates the novel approach of coupling separate energy harvesters in order to scavenge more power from a stochastic point of view. To this end, a multi-body system composed of two cantilever harvesters with two identical piezoelectric patches is considered. The beams are interconnected through a linear spring. Assuming a stochastic band limited white noise excitation of the base, the statistical properties of the mechanical response and those of the generated voltages are derived in closed form. Moreover, analytical models are derived for the expected value of the total harvested energy. In order to maximize the expected generated power, an optimization is performed to determine the optimum physical and geometrical characteristics of the system. It is observed that by properly tuning the harvester parameters, the energy harvesting performance of the structure is remarkably improved. Furthermore, using an optimized energy harvester model, this study shows that the coupling of the beams negatively affects the scavenged power, contrary to the effect previously demonstrated for harvesters under harmonic excitation. The qualitative and quantitative knowledge resulting from this analysis can be effectively employed for the realistic design and modelling of coupled multi-body structures under stochastic excitations.

scholarly journals Relations among the Riemann Zeta and Hurwitz Zeta Functions, as Well as Their Products

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 754 ◽  
Author(s):  
A. C. L. Ashton ◽  
A. S. Fokas
Keyword(s):  
Zeta Function ◽  
Zeta Functions ◽  
Formal Proof ◽  
Hurwitz Zeta Function ◽  
Mean Square ◽  
Novel Approach ◽  
Starting Point ◽  
Lindelöf Hypothesis ◽  
Riemann Zeta ◽  
The Mean

In this paper, several relations are obtained among the Riemann zeta and Hurwitz zeta functions, as well as their products. A particular case of these relations give rise to a simple re-derivation of the important results of Katsurada and Matsumoto on the mean square of the Hurwitz zeta function. Also, a relation derived here provides the starting point of a novel approach which, in a series of companion papers, yields a formal proof of the Lindelöf hypothesis. Some of the above relations motivate the need for analysing the large α behaviour of the modified Hurwitz zeta function ζ 1 ( s , α ) , s ∈ C , α ∈ ( 0 , ∞ ) , which is also presented here.

scholarly journals A metaheuristic penalty approach for the starting point in nonlinear programming

2020 ◽  
Vol 54 (2) ◽  
pp. 451-469
Author(s):  
David R. Penas ◽  
Marcos Raydan
Keyword(s):  
Nonlinear Programming ◽  
Feasible Solution ◽  
Packing Problem ◽  
Merit Function ◽  
Test Problems ◽  
Huge Amount ◽  
Novel Approach ◽  
Starting Point ◽  
Metaheuristic Techniques ◽  
Optimization Schemes

Solving nonlinear programming problems usually involve difficulties to obtain a starting point that produces convergence to a local feasible solution, for which the objective function value is sufficiently good. A novel approach is proposed, combining metaheuristic techniques with modern deterministic optimization schemes, with the aim to solve a sequence of penalized related problems to generate convenient starting points. The metaheuristic ideas are used to choose the penalty parameters associated with the constraints, and for each set of penalty parameters a deterministic scheme is used to evaluate a properly chosen metaheuristic merit function. Based on this starting-point approach, we describe two different strategies for solving the nonlinear programming problem. We illustrate the properties of the combined schemes on three nonlinear programming benchmark-test problems, and also on the well-known and hard-to-solve disk-packing problem, that possesses a huge amount of local-nonglobal solutions, obtaining encouraging results both in terms of optimality and feasibility.

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