A new tool for two and three dimensional rockfall analysis and cross sectional hazard mapping; case study: rockfall problem in Bolhayat Cape, Shiraz-Ahwaz highway

2004 ◽  
pp. 515-520
Author(s):  
M Meidani ◽  
N Hataf
Keyword(s):  
Three Dimensional ◽  
Hazard Mapping ◽  
Cross Sectional

scholarly journals Experimental Investigations of Interactions between Sand Wave Movements, Flow Structure, and Individual Aquatic Plants in Natural Rivers: A Case Study of Potamogeton Pectinatus L.

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1166 ◽  
Author(s):  
Łukasz Przyborowski ◽  
Anna Łoboda ◽  
Robert Bialik
Keyword(s):  
Flow Velocity ◽  
Three Dimensional ◽  
Potamogeton Pectinatus ◽  
Sand Wave ◽  
Experimental Investigations ◽  
Cross Sectional ◽  
Bending Tests ◽  
Long Duration ◽  
Elevation Changes

Long-duration measurements were performed in two sandy bed rivers, and three-dimensional (3D) flow velocity and bottom elevation changes were measured in a vegetated area and in a clear region of a river. Detailed flow velocity profiles downstream and upstream of a single specimen of Potamogeton pectinatus L. were obtained and the bed morphology was assessed. Potamogeton plants gathered from each river were subjected to tensile and bending tests. The results show that the existence of the plants was influenced by both bottom and flow conditions, as the plants were located where water velocity was lower by 12% to 16% in comparison to clear region. The characteristics of the flow and sand forms depended on the cross-sectional arrangement of the river, e.g., dunes were approximately four times higher in the middle of the river than in vegetated regions near the bank. Furthermore, the studied hydrophytes were too sparse to affect water flow and had no discernible impact on the sand forms’ movements. The turbulent kinetic energy downstream of a single plant was reduced by approximately 25%. Additionally, the plants’ biomechanical characteristics and morphology were found to have adjusted to match the river conditions.

scholarly journals An Analytical Formulation for the Lateral Support Stiffness of a Spatial Flexure Strip

2015 ◽  
Author(s):  
Marijn Nijenhuis ◽  
J. P. Meijaard ◽  
Just L. Herder ◽  
Shorya Awtar ◽  
Dannis M. Brouwer
Keyword(s):  
Three Dimensional ◽  
Beam Element ◽  
Element Analysis ◽  
Cross Sectional ◽  
Flexure Mechanism ◽  
Stiffness Properties ◽  
Spatial Beam ◽  
Discrete Nature ◽  
Stiffness Characteristics

A flexure strip has constraint characteristics, such as stiffness properties and error motions, that limit its performance as a basic constituent of flexure mechanisms. This paper presents a framework for modeling the deformation and stiffness characteristics of general three-dimensional flexure strips that exhibit bending, shear and torsion deformation. The formulation is based on a finite strain discrete spatial beam element with refinements to account for plate-like behavior due to constrained cross-sectional warping. This framework is suited for analytical calculations thanks to the accuracy of the beam element, while its discrete nature allows for easy implementation in numeric software to serve as calculation aid. As case study, a closed-form parametric analytical expression is derived for the lateral support stiffness of a parallel flexure mechanism. This captures the deteriorating support stiffness when the mechanism moves in the intended degree of freedom. By incorporating relevant geometric nonlinearities and a warping constraint stiffening factor, an accurate load-displacement and stiffness expression for the lateral support direction is obtained. This result is verified by nonlinear finite element analysis.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

Impacts of Sample Preparation Methodology on TEM Failure Analysis of Advanced Semiconductor Devices

2011 ◽  
Author(s):  
Yongkai Zhou ◽  
Jie Zhu ◽  
Han Wei Teo ◽  
ACT Quah ◽  
Lei Zhu ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Failure Analysis ◽  
Case Studies ◽  
Thickness Measurement ◽  
Interface Roughness ◽  
Silicide Formation ◽  
Cross Sectional ◽  
Inspection Method ◽  
Low Mass

Abstract In this paper, two failure analysis case studies are presented to demonstrate the importance of sample preparation procedures to successful failure analyses. Case study 1 establishes that Palladium (Pd) cannot be used as pre-FIB coating for SiO2 thickness measurement due to the spontaneously Pd silicide formation at the SiO2/Si interface. Platinum (Pt) is thus recommended, in spite of the Pt/SiO2 interface roughness, as the pre-FIB coating in this application. In the second case study, the dual-directional TEM inspection method is applied to characterize the profile of the “invisible” tungsten residue defect. The tungsten residue appears invisible in the planeview specimen due to the low mass-thickness contrast. It is then revealed in the cross-sectional TEM inspection.

scholarly journals Accuracy and Reproducibility of Facial Measurements of Digital Photographs and Wrapped Cone Beam Computed Tomography (CBCT) Photographs

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 757
Author(s):  
Maged Sultan Alhammadi ◽  
Abeer Abdulkareem Al-mashraqi ◽  
Rayid Hussain Alnami ◽  
Nawaf Mohammad Ashqar ◽  
Omar Hassan Alamir ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Cone Beam Computed Tomography ◽  
High Reliability ◽  
Three Dimensional ◽  
Cone Beam ◽  
Cross Sectional ◽  
Facial Profile ◽  
Digital Photographs ◽  
Gonial Angle

The study sought to assess whether the soft tissue facial profile measurements of direct Cone Beam Computed Tomography (CBCT) and wrapped CBCT images of non-standardized facial photographs are accurate compared to the standardized digital photographs. In this cross-sectional study, 60 patients with an age range of 18–30 years, who were indicated for CBCT, were enrolled. Two facial photographs were taken per patient: standardized and random (non-standardized). The non-standardized ones were wrapped with the CBCT images. The most used soft tissue facial profile landmarks/parameters (linear and angular) were measured on direct soft tissue three-dimensional (3D) images and on the photographs wrapped over the 3D-CBCT images, and then compared to the standardized photographs. The reliability analysis was performed using concordance correlation coefficients (CCC) and depicted graphically using Bland–Altman plots. Most of the linear and angular measurements showed high reliability (0.91 to 0.998). Nevertheless, four soft tissue measurements were unreliable; namely, posterior gonial angle (0.085 and 0.11 for wrapped and direct CBCT soft tissue, respectively), mandibular plane angle (0.006 and 0.0016 for wrapped and direct CBCT soft tissue, respectively), posterior facial height (0.63 and 0.62 for wrapped and direct CBCT soft tissue, respectively) and total soft tissue facial convexity (0.52 for both wrapped and direct CBCT soft tissue, respectively). The soft tissue facial profile measurements from either the direct 3D-CBCT images or the wrapped CBCT images of non-standardized frontal photographs were accurate, and can be used to analyze most of the soft tissue facial profile measurements.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

scholarly journals Generative Models for Relief Perspective Architectures

2021 ◽  
Author(s):  
Leonardo Baglioni ◽  
Federico Fallavollita
Keyword(s):  
Research Methodology ◽  
Affine Space ◽  
Three Dimensional ◽  
Generative Models ◽  
Linear Perspective ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Present Essay ◽  
Santa Maria

AbstractThe present essay investigates the potential of generative representation applied to the study of relief perspective architectures realized in Italy between the sixteenth and seventeenth centuries. In arts, and architecture in particular, relief perspective is a three-dimensional structure able to create the illusion of great depths in small spaces. A method of investigation applied to the case study of the Avila Chapel in Santa Maria in Trastevere in Rome (Antonio Gherardi 1678) is proposed. The research methodology can be extended to other cases and is based on the use of a Relief Perspective Camera, which can create both a linear perspective and a relief perspective. Experimenting mechanically and automatically the perspective transformations from the affine space to the illusory space and vice versa has allowed us to see the case study in a different light.

Decolonising a landscape architecture studio: Spatial modelling of student narratives

2021 ◽  
Vol 1 (1) ◽  
pp. 39-47
Author(s):  
Christine Price
Keyword(s):  
Spatial Model ◽  
Meaning Making ◽  
Three Dimensional ◽  
Spatial Modelling ◽  
First Year ◽  
Spatial Form ◽  
Public Park ◽  
New Meanings ◽  
Global North

This paper problematises the dominance of global north perspectives in landscape architectural education, in South Africa where there are urgent calls to decolonise education and make visible indigenous and vernacular meaning-making practices. In grappling with these concerns, this research finds resonance with a multimodal social semiotic approach that acknowledges the interest, agency and resourcefulness of students as meaning-makers in both accessing and challenging dominant educational discourses. This research involves a case study of a design project in a first-year landscape architectural studio. The project requires students to choose a narrative and to represent it as a spatial model: a scaled, 3D maquette of a spatial experience that could be installed in a public park. This practitioner reflection closely analyses the spatial model of one student, Malibongwe, focusing on his interest in meaning-making; the innovative meaning-making practices and diverse resources he draws on; and his expression of spatial signifiers of the Black experiences portrayed in his narrative. This reflection shows how Malibongwe’s narrative is not only reproduced in the spatial model, it is remade: the transformation of resources into three-dimensional spatial form results in new understandings and the production of new meanings.

scholarly journals Unexpected Diversity in Regenerating Sites Stresses the Importance of Baselines: A Case Study With Bats (Order Chiroptera) on the Osa Peninsula, Costa Rica

2021 ◽  
Vol 14 ◽  
pp. 194008292110281
Author(s):  
Elène Haave-Audet ◽  
Doris Audet ◽  
Michelle Monge-Velazquez ◽  
Eleanor Flatt ◽  
Andrew Whitworth
Keyword(s):  
Habitat Restoration ◽  
Insect Pest ◽  
Community Diversity ◽  
Baseline Survey ◽  
Cross Sectional ◽  
Osa Peninsula ◽  
The Family ◽  
Aerial Insectivores ◽  
Baseline State

Introduction: Background and Research Aims: Assessing biodiversity recovery is key to determine whether the objectives of habitat restoration for conservation are met. Many restoration initiatives use cross-sectional comparisons of wildlife communities to infer restoration impact instead of longitudinal assessments from a baseline state. Using an indicator of biodiversity in the neotropics— bats— we demonstrate how assessing community diversity and composition in an area targeted for restoration prior to implementation, and when compared to surrounding intact forest, provides the groundwork to track changes in the community post-restoration. Methods We assessed bat communities by 1) using mist-net surveys to identify species in the family Phyllostomidae (leaf-nosed bats), and 2) conducting acoustic surveys to identify non-phyllostomid species (aerial insectivores). Results For both groups, we found that areas targeted for restoration had similar diversity as the surrounding forest, but the two habitat types differed in community composition. Phyllostomids were captured at higher rates in forest, but aerial insectivores were detected at higher rates in restoration habitat. Conclusion Our baseline assessment revealed unexpected diversity in areas targeted for restoration. The presence of all trophic groups in restoration habitat suggests that bats provide key ecosystem services in the restoration process, such as through seed dispersal, pollination and insect pest control. Implications for Conservation: Conducting a baseline survey of bats in areas targeted for restoration demonstrated that the community was not species poor at the baseline and was different from the surrounding forest, allowing us to better track restoration success and the effects of different restoration treatments.

Sign in / Sign up

Export Citation Format

Share Document