Interaction, instability, and simultaneity of debonding processes in flexure of masonry walls strengthened on two sides with FRP

This paper studies the interactive, simultaneous, and unstable multiple debonding mechanisms in masonry walls strengthened to resist out-of-plane flexure using composite materials bonded on their tensed and compressed faces. This structural form combines rigid blocks and brittle joints sandwiched between adhesively bonded composite layers. It characterizes masonry walls strengthened to resist dynamic and seismic out-of-plane loads, but also armor plates with ceramic tiles, electronic packaging, and sandwich panels with embedded inserts. The study focuses on the stability of the interactive debonding mechanisms and on the potential evolution of coupled and simultaneous debonding processes. It uses a cohesive interface approach and a geometrically nonlinear high order model. A numerical study that examines the coupled debonding processes in masonry wall samples strengthened with composite materials on the two outer faces is presented. The study examines the instabilities involved with the processes, the order in which the tension driven debonding and the buckling driven one nucleate, and the interaction between them. It also examines the impact of the properties of the cohesive interface, the presence of pre-existing debonded regions, the arching effect, and the accumulation of damage at the interfaces. This effort aims to gain insight into the debonding processes and their impact on the performance, functionality, and safety of the strengthened element.     

The paradox of oil reserve forecasts: The political implications of predicting oil reserves and oil consumption

In the light of the outstanding importance of hydrocarbons for global energy, the controversy over peak oil has become both pressing and emotionally charged. Two conflicting parties – alarmists and optimists – hold irreconcilable positions. The shaping of the future energy policy is presently based on modeling results and geological considerations only. We show that the existing predictions of the energy crisis are increasingly mixed-up with value-judgments. The value analysis of those forecasts allows us to suggest that at least part of the estimations are implicit reflections of predictors’ ends and values, and do not demonstrate a real ability to anticipate future conditions. Paradoxically, the question of oil reserves depletion is better understood when predictions are viewed as an instrument to impose the predictors’ values and intervene in the currently bustling oil market. The intervention in the oil prices may occur in either direction becoming a tool to justify values rather than an instrument for the acquisition of knowledge.     

Buckling-driven debonding in stiff block: compliant joint structural assemblies patched with composite materials

The initiation, growth, and stability of buckling driven debonding in structural assemblies of stiff blocks, compliant joints, and adhesively bonded composite layers are analytically investigated. The model is developed with focus on masonry walls externally strengthened with composite materials where static and, mainly, dynamic loads may induce compression in the strengthening layers triggering a buckling driven debonding near the joints. The model introduces the interfacial nonlinearity (debonding) through a cohesive interface approach. The geometrical nonlinearity is introduced through the kinematics of intermediate class of deformation (large deflections, moderate rotations, small strains), and the material nonlinearity of the masonry construction is introduced through the constitutive law for the mortar joints. A numerical study of the debonding process in strengthened masonry walls is presented. The study uses the periodicity of the wall for sub-structuring and examines configurations that include composite strips or sheets, strengthening on one face of the wall or on both faces, and compliant mortar materials. Emphasis is placed on the localized debonding near the joint, its stability characteristics, and the possibility to detect the debonding process before it reaches the point of instability.     

Dynamic routing in reentrant flexible manufacturing systems

Consider a flexible manufacturing system (FMS), with several parallel production lines. Each line is statistically balanced. Due to process time and yield variations, some workstations may be temporarily starved of parts during the FMS operation, while others may have too many. The purpose of the dynamic routing algorithm described here is to achieve real-time load balancing in a stochastic processing environment and thus to increase the performance of the system in throughput, workload balance and reduced work-in-process queues. We formulate the problem and develop an optimal stationary policy (for two lines that have a material handling transport between them) based on the input buffer state of each station.     

AMT 2.0: qualitative and quantitative trace analysis with extended signal temporal logic

International Journal on Software Tools for Technology Transfer - We introduce in this paper $$\text {AMT} \; 2.0$$ , a tool for qualitative and quantitative analysis of hybrid continuous and...     

A Simple Discretization of the Vector Dirichlet Energy

We present a simple and concise discretization of the covariant derivative vector Dirichlet energy for triangle meshes in 3D using Crouzeix-Raviart finite elements. The discretization is based on linear discontinuous Galerkin elements, and is simple to implement, without compromising on quality: there are two degrees of freedom for each mesh edge, and the sparse Dirichlet energy matrix can be constructed in a single pass over all triangles using a short formula that only depends on the edge lengths, reminiscent of the scalar cotangent Laplacian. Our vector Dirichlet energy discretization can be used in a variety of applications, such as the calculation of Killing fields, parallel transport of vectors, and smooth vector field design. Experiments suggest convergence and suitability for applications similar to other discretizations of the vector Dirichlet energy.     

Utilizing digital traces of mobile phones for understanding social dynamics in urban areas

Understanding land use in urban areas, from the perspective of social function, is beneficial for a variety of fields, including urban and highway planning     

GYO reductions,canonical connections,tree and cyclic schemas,and tree projections

Database schemas may be partitioned into two subclasses: three schemas and cyclic schemas. The analysis of tree vs . cyclic schemas introduced the concepts of GYO reductions, canonical connections, and tree projections. This paper investigates the intricate relationships among these concepts in the context of universal relation databases.