Numerical investigation of fracture of polycrystalline ice under dynamic loading

Cohesive zone model is a promising technique for simulating fracture processes in brittle ice. In this work it is applied to investigate the fracture behavior of polycrystalline cylindrical samples under uniaxial loading conditions, four-point beam bending, and L-shaped beam bending. In each case, the simulation results are compared with the corresponding experimental data that was collected by other researchers. The model is based on the implicit finite element method combined with Park-Paulino-Roesler formulation for cohesive potential and includes an adaptive time stepping scheme, which takes into account the rate of damage and failure of cohesive zones. The benefit of the implicit scheme is that it allows larger time steps than explicit integration. Material properties and model parameters are calibrated using available experimental data for freshwater ice and sea ice samples. For polycrystalline ice, granular geometry is generated and cohesive zones are inserted between grains. Simulations are performed for samples with different grain sizes, and the resulting stress–strain and damage accumulation curves are recorded. Investigation of the dependency between the grain size and fracture strength shows a strengthening effect that is consistent with experimental results. The proposed framework is also applied to simulate the dynamic fracture processes in Lshaped beams of sea ice, in which case the cohesive zones are inserted between the elements of the mesh. Evolution of the stress distribution on the surface of the beam is modeled for the duration of the loading process, showing how it changes with progressive accumulation of damage in the material, as well as the development of cracks. An analytical formula is derived for estimating the breaking force based on the dimensions of the beam and the ice strength. Experimental data obtained from the 2014-2016 tests are re-evaluated with the aid of this new analysis. The computation is implemented efficiently with GPU acceleration, allowing to handle geometries with higher resolution than would be possible otherwise. Several technical contributions are described in detail including GPU-accelerated FEM implementation, an efficient way of creation of sparse matrix structure, and comparison of different unloading/reloading relations when using an implicit integration scheme. A mechanism for collision response allows modeling the interaction of fragmented material. To evaluate the collision forces, an algorithm for computing first and second point-triangle distance derivatives was developed. The source code is made available as open-source

KINE[SIS]TEM'17 From Nature to Architectural Matter

Kine[SiS]tem – From Kinesis + System. Kinesis is a non-linear movement or activity of an organism in response to a stimulus. A system is a set of interacting and interdependent agents forming a complex whole, delineated by its spatial and temporal boundaries, influenced by its environment. How can architectural systems moderate the external environment to enhance comfort conditions in a simple, sustainable and smart way? This is the starting question for the Kine[SiS]tem’17 – From Nature to Architectural Matter International Conference. For decades, architectural design was developed despite (and not with) the climate, based on mechanical heating and cooling. Today, the argument for net zero energy buildings needs very effective strategies to reduce energy requirements. The challenge ahead requires design processes that are built upon consolidated knowledge, make use of advanced technologies and are inspired by nature. These design processes should lead to responsive smart systems that deliver the best performance in each specific design scenario. To control solar radiation is one key factor in low-energy thermal comfort. Computational-controlled sensor-based kinetic surfaces are one of the possible answers to control solar energy in an effective way, within the scope of contradictory objectives throughout the year.FC

GIS-based cultural route heritage authenticity analysis and conservation support in cost-surface and visibility study approaches.

He, Jie.Thesis submitted in: October 2008.Thesis (Ph.D.)--Chinese University of Hong Kong, 2009.Includes bibliographical references (leaves 219-236).Abstracts in English and Chinese.ABSTRACT --- p.iTABLE OF CONTENTS --- p.vLIST OF FIGURES --- p.ixACKNOWLEDGEMENTS --- p.xiiiChapter Chapter 1 --- INTRODUCTION --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.1.1 --- The Development of the Cultural Route Concept --- p.2Chapter 1.1.2 --- The Delimitation of Heritage Definitions and Conservation --- p.5Chapter 1.2 --- Research Questions --- p.7Chapter 1.2.1 --- Shortcomings of Delimitations and Their Implementation in Cultural Routes --- p.7Chapter 1.2.2 --- Authenticity as a Subject of Investigation and Planning Support --- p.11Chapter 1.3 --- Research Definition --- p.12Chapter 1.3.1 --- Research Objectives --- p.13Chapter 1.3.2 --- Significance of Study --- p.13Chapter Chapter 2 --- LITERATURE REVIEW --- p.15Chapter 2.1 --- Cultural Route Heritage Disciplines and Protection Practices --- p.15Chapter 2.1.1 --- Theoretical and Methodological Investigations --- p.15Chapter 2.1.2 --- Delimitations and Case Studies --- p.17Chapter 2.2 --- Routes and Associated Landscape Studies carried out by Archaeologists --- p.24Chapter 2.2.1 --- Archaeological Route Studies --- p.25Chapter 2.2.2 --- Landscape Archaeological Module and Cases --- p.26Chapter 2.2.3 --- Methodology and technology --- p.29Chapter 2.3 --- "Landscape Archaeology and ,GIS applications" --- p.29Chapter 2.3.1 --- Landscape Archaeology through the Cognitive Paradigm --- p.30Chapter 2.3.2 --- Information Technology and GIS Support --- p.31Chapter 2.3.3 --- GIS Support for Heritage --- p.33Chapter 2.4 --- GIS for Cultural Resource Management --- p.34Chapter 2.4.1 --- Gap between Practice and Research --- p.35Chapter 2.4.2 --- The Potential of GIS for Conservation Planning in CRM --- p.37Chapter 2.4.3 --- Problems in Gonservation Planning Relating to Heritage Value --- p.39Chapter 2.5 --- Perceptual Archaeology and GIS Applications. --- p.40Chapter 2.5.1 --- Archaeological Yisibility --- p.41Chapter 2.5.2 --- Cost Surface Analysis --- p.47Chapter 2.6 --- Problem-oriented Applications of Visibility and Cost-surface Analysis --- p.50Chapter 2.6.1 --- Single Factor Approaches --- p.50Chapter 2.6.2 --- Social and Cultural Interpretations --- p.52Chapter 2.6.3 --- Path Studies --- p.53Chapter 2.7 --- Visual Resource Management Researches by the Author --- p.54Chapter 2.8 --- Summary and Discussion --- p.54Chapter Chapter 3 --- SYSTEM DESIGN --- p.59Chapter 3.1 --- Research Questions --- p.59Chapter 3.1.1 --- Authenticity and the Reified Attributes --- p.60Chapter 3.1.2 --- Definition of Attributes --- p.62Chapter 3.1.3 --- Authenticity Interpretations through Spatial Interrelationships --- p.65Chapter 3.1.4 --- Authenticity Interpretations through Functionalities --- p.67Chapter 3.1.5 --- The Scale Issue --- p.69Chapter 3.1.6 --- Technical Potentials in GIS --- p.70Chapter 3.2 --- The System Framework --- p.71Chapter 3.2.1 --- Path Replication and Prediction --- p.73Chapter 3.2.2 --- Control of Space --- p.77Chapter 3.2.3 --- Cultural Landscapes in Cultural Route Spatial Analysis --- p.82Chapter 3.3 --- Management and Delimitations --- p.85Chapter 3.3.1 --- Allocations --- p.85Chapter 3.3.2 --- Delimitations in Categories --- p.86Chapter 3.4 --- Summary --- p.90Chapter Chapter 4 --- RESEARCH METHODOLOGY --- p.91Chapter 4.1 --- Background Dataset. --- p.91Chapter 4.1.1 --- DEM --- p.91Chapter 4.1.2 --- Mapping Scales --- p.96Chapter 4.1.3 --- "Historical Topography and Landscape Reconstruction," --- p.98Chapter 4.2 --- Cost Surface Analysis --- p.102Chapter 4.2.1 --- Movement Singulation --- p.103Chapter 4.2.2 --- Path Selection --- p.105Chapter 4.3 --- Cost Surface Modeling --- p.107Chapter 4.3.1 --- Attributes Introduced --- p.108Chapter 4.3.2 --- Cost-Surface Model Making --- p.110Chapter 4.3.3 --- Visibility as a Cost --- p.114Chapter 4.3.4 --- Algorithms --- p.121Chapter 4.3.5 --- rSpatial Control of Property --- p.128Chapter 4.4 --- Technical Issues and Validation --- p.137Chapter 4.4.1 --- Technical Issues of Visibility Studies --- p.138Chapter 4.4.2 --- Cost-Surface Analysis Conberns --- p.141Chapter 4.4.3 --- Validations --- p.142Chapter 4.5 --- Summary --- p.143Chapter Chapter 5 --- CASE STUDY OF THE GREAT WALL --- p.145Chapter 5.1 --- Background --- p.145Chapter 5.1.1 --- Previous Research --- p.145Chapter 5.1.2 --- Great Wall Conservation --- p.149Chapter 5.2 --- Case Study Design --- p.150Chapter 5.3 --- Data Sources and Data Preparation --- p.151Chapter 5.3.1 --- DEM --- p.151Chapter 5.3.2 --- Historical Reconstructions --- p.156Chapter 5.4 --- Large-scale Analyses --- p.162Chapter 5.4.1 --- Cost-surface Modeling --- p.163Chapter 5.4.2 --- Invasion and Defensive Interpretations --- p.166Chapter 5.5 --- The Juyongguan Pass Study --- p.178Chapter 5.5.1 --- Research Background --- p.181Chapter 5.5.2 --- Facility Mapping and Viewshed Analysis --- p.181Chapter 5.5.3 --- Movement Modeling --- p.191Chapter 5.5.4 --- Analytical Results --- p.195Chapter 5.6 --- Spatial Control and Delimitations of Juyongguan Pass Fortress --- p.201Chapter 5.6.1 --- Spatial Control of the Great Wall --- p.201Chapter 5.6.2 --- Juyongguan Pass Fortress Delimitations --- p.203Chapter 5.7 --- Summary and Discussion --- p.209Chapter Chapter 6 --- CONCLUSION AND DISCUSSION --- p.211Chapter 6.1 --- Utility of the Proposed Study Scheme --- p.211Chapter 6.1.1 --- The Theoretical Aspect --- p.211Chapter 6.1.2 --- Methodological Aspect --- p.212Chapter 6.1.3 --- Conservation Practice --- p.213Chapter 6.2 --- Research Contributions and Limitations --- p.214Chapter 6.3 --- Further Research --- p.215REFERENCES --- p.21

Material-based design computation

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 306-328).The institutionalized separation between form, structure and material, deeply embedded in modernist design theory, paralleled by a methodological partitioning between modeling, analysis and fabrication, resulted in geometric-driven form generation. Such prioritization of form over material was carried into the development and design logic of CAD. Today, under the imperatives and growing recognition of the failures and environmental liabilities of this approach, modern design culture is experiencing a shift to material aware design. Inspired by Nature's strategies where form generation is driven by maximal performance with minimal resources through local material property variation, the research reviews, proposes and develops models and processes for a material-based approach in computationally enabled form-generation. Material-based Design Computation is developed and proposed as a set of computational strategies supporting the integration of form, material and structure by incorporating physical form-finding strategies with digital analysis and fabrication. In this approach, material precedes shape, and it is the structuring of material properties as a function of structural and environmental performance that generates design form. The thesis proposes a unique approach to computationally-enabled form-finding procedures, and experimentally investigates how such processes contribute to novel ways of creating, distributing and depositing material forms. Variable Property Design is investigated as a theoretical and technical framework by which to model, analyze and fabricate objects with graduated properties designed to correspond to multiple and continuously varied functional constraints. The following methods were developed as the enabling mechanisms of Material Computation: Tiling Behavior & Digital Anisotropy, Finite Element Synthesis, and Material Pixels. In order to implement this approach as a fabrication process, a novel fabrication technology, termed Variable Property Rapid Prototyping has been developed, designed and patented. Among the potential contributions is the achievement of a high degree of customization through material heterogeneity as compared to conventional design of components and assemblies. Experimental designs employing suggested theoretical and technical frameworks, methods and techniques are presented, discussed and demonstrated. They support product customization, rapid augmentation and variable property fabrication. Developed as approximations of natural formation processes, these design experiments demonstrate the contribution and the potential future of a new design and research field.by Neri Oxman.Ph.D

Responsive Architecture

This book is a collection of articles that have been published in the Special Issue “Responsive Architecture” of the MDPI journal Buildings. The eleven articles within cover various areas of sensitive architecture, including the design of packaging structures reacting to supporting components; structural efficiency of bent columns in indigenous houses; roof forms responsive to buildings depending on their resiliently transformed steel shell parts; creative design of building free shapes covered with transformed shells; artistic structural concepts of the architect and civil engineer; digitally designed airport terminal using wind analysis; rationalized shaping of sensitive curvilinear steel construction; interactive stories of responsive architecture; transformed shell roof constructions as the main determinant in the creative shaping of buildings without shapes that are sensitive to man-made and natural environments; thermally sensitive performances of a special shielding envelope on balconies; quantification of generality and adaptability of building layout using the SAGA method; and influence of initial conditions on the simulation of the transient temperature field inside a wall

Numerical modeling of thermal bar and stratification pattern in Lake Ontario using the EFDC model

Thermal bar is an important phenomenon in large, temperate lakes like Lake Ontario. Spring thermal bar formation reduces horizontal mixing, which in turn, inhibits the exchange of nutrients. Evolution of the spring thermal bar through Lake Ontario is simulated using the 3D hydrodynamic model Environmental Fluid Dynamics Code (EFDC). The model is forced with the hourly meteorological data from weather stations around the lake, flow data for Niagara and St. Lawrence rivers, and lake bathymetry. The simulation is performed from April to July, 2011; on a 2-km grid. The numerical model has been calibrated by specifying: appropriate initial temperature and solar radiation attenuation coefficients. The existing evaporation algorithm in EFDC is updated to modified mass transfer approach to ensure correct simulation of evaporation rate and latent heatflux. Reasonable values for mixing coefficients are specified based on sensitivity analyses. The model simulates overall surface temperature profiles well (RMSEs between 1-2°C). The vertical temperature profiles during the lake mixed phase are captured well (RMSEs < 0.5°C), indicating that the model sufficiently replicates the thermal bar evolution process. An update of vertical mixing coefficients is under investigation to improve the summer thermal stratification pattern. Keywords: Hydrodynamics, Thermal BAR, Lake Ontario, GIS