Computer method for analysis of multistory structures

A computer method for three dimensional analysis of multistory structures is presented. There are no restrictions referring to types of stiffening elements, their layout and changes in floor plane and variations in cross-sectional properties with height of the structure. The number of stiffening elements which may be included in analysis is practically unlimited. The loads may be vertical and lateral at arbitrary locations. Elastic warping of thin-walled members is included in analysis. The macro-flow-chart of the computer program and results of a numerical example is given.     

CIB Working Commissions W57 and W74

Prof. Colin Davidson, Faculté de l'aménagement, Université de Montréal; Philippe Davidson, National Research Council of Canada, NRCC; David Jaggar, Liverpool Polytechnic; and Kalev Ruberg, NRCC, report on the CIB survey of educational establishments showing that information science and information management is taught in less than half the programmes surveyed, and discuss the difficult task of the acquisition of expert information, as well as the need to match information provided with practitioners’ real needs.     

Bumblebee communities as an indicator for landscape monitoring in the agri-environmental programme

The current article focuses on the possibilities of applying bumblebees as one of the biodiversity indicators in the monitoring and evaluation of the Estonian Agri-Environmental Programme (AEP) at landscape level. The need for agri-environmental indicators arises, at least partially, because the desired state of the environment sought by policy makers may not be directly observable. To develop agri-environmental measures favourable to landscape quality, it is necessary to know more about the relationship between landscape structure and composition and the number of different species. This study tested the relationship between the data sets of landscape elements and bumblebee communities from 11 agricultural areas in Estonia. The localities were divided into two groups: intensively used agricultural areas (IA) (the percentage of arable land was >65%) and less intensively used agricultural areas (LIA) (the percentage of arable land was <45%). The following elements of landscape structure were analysed: buffer zones narrower than 5 m and wider than 5 m, ecotones between cultivated land and broad-leaved forests, ecotones between cultivated land and mixed or coniferous forests, ditches and brooks, fallow land, mixed forests, coniferous forests, broad-leaved forests, bushes, wetlands, cultivated grasslands, pastures, legumes, arable land, semi-natural grasslands. Fifteen bumblebee species were recorded in LIA and 13 in IA. The most widely distributed and abundant species were Bombus lucorum, Bombus pascuorum and Bombus lapidarius. These species dominated in both types of agricultural area. Two species, Bombus jonellus and Bombus hypnorum were found only in LIA. Principal component analysis (PCA) was applied to the landscape elements and the bumblebee species found. Results showed that there was a significant co-structure between the data sets of landscape elements and bumblebee communities. The most important landscape features that correlated with the distribution of the bumblebee species were the ecotone length between cultivated land and forests, and the size of the area covered with mixed forests and wetlands.     

Drivers of European landscape change: stakeholders’ perspectives through Fuzzy Cognitive Mapping

Understanding complex processes of landscape change is crucial to guide the development of future landscapes and land resources. Through Fuzzy Cognitive Mapping, we studied the processes of landscape change of six different environmental zones in Europe. Results show that landscapes are complex systems, with many interactions. Except for one, all regions show a strong decline in landscape quality. Dominant drivers are EU policy and the global economy, sometimes in conjunction with environmental drivers or the governance system. The process of change differs for all cases, through urbanisation or land abandonment in some cases, and agricultural intensification in others. The (un)intended effects of policies are difficult to predict. Although some EU Policies directly improve landscape quality, their indirect effects as well as other EU policies outweigh this positive influence and jointly result in a decrease of landscape quality. To counter these negative side effects, targeted landscape policies are urgently needed.     

Cyclic elastic-plastic dynamic analysis by the finite element method

A finite element approach for cyclic elastic-plastic dynamic analysis is presented. A hardening model suited for cyclic plasticity behavior is incorporated. It is composed of several yield surfaces, and nonlinear stress-strain curves can be included. The central difference timewise operator is employed to solve the equations of motion. Comparison is made with the Newmark operator. Numerical examples illustrate the effect of cyclic plastic deformations on the dynamic response of simple problems. Comparison is presented for the structural behavior as predicted by the present hardening model and by the isotropic hardening model.     

Cyclic plasticity models and application in fatigue analysis

An analytical procedure for prediction of the cyclic plasticity effects on both the structural fatigue life to crack initiation and the rate of crack growth is presented. The crack initiation criterion is based on the Coffin-Manson formulae extended for multiaxial stress state and for inclusion of the mean stress effect. This criterion is also applied for the accumulated damage ahead of the existing crack tip which is assumed to be related to the crack growth rate. Three cyclic plasticity models, based on the concept of combination of several yield surfaces, are employed for computing the crack growth rate of a cracked plane stress panel under several cyclic loading conditions.     

Localised boundary air layer and clothing evaporative resistances for individual body segments

Evaporative resistance is an important parameter to characterise clothing thermal comfort. However, previous work has focused mainly on either total static or dynamic evaporative resistance. There is a lack of investigation of localised clothing evaporative resistance. The objective of this study was to study localised evaporative resistance using sweating thermal manikins. The individual and interaction effects of air and body movements on localised resultant evaporative resistance were examined in a strict protocol. The boundary air layer's localised evaporative resistance was investigated on nude sweating manikins at three different air velocity levels (0.18, 0.48 and 0.78 m/s) and three different walking speeds (0, 0.96 and 1.17 m/s). Similarly, localised clothing evaporative resistance was measured on sweating manikins at three different air velocities (0.13, 0.48 and 0.70 m/s) and three walking speeds (0, 0.96 and 1.17 m/s). Results showed that the wind speed has distinct effects on local body segments. In contrast, walking speed brought much more effect on the limbs, such as thigh and forearm, than on body torso, such as back and waist. In addition, the combined effect of body and air movement on localised evaporative resistance demonstrated that the walking effect has more influence on the extremities than on the torso. Therefore, localised evaporative resistance values should be provided when reporting test results in order to clearly describe clothing local moisture transfer characteristics. PRACTITIONER SUMMARY: Localised boundary air layer and clothing evaporative resistances are essential data for clothing design and assessment of thermal comfort. A comprehensive understanding of the effects of air and body movement on localised evaporative resistance is also necessary by both textile and apparel researchers and industry.     

Control of High-Speed Solid-Rotor Synchronous Reluctance Motor/Generator for Flywheel-Based Uninterruptible Power Supplies

A hybrid controller, consisting of a model-based feedforward controller and a proportional–integral feedback compensator, for a solid-rotor synchronous reluctance motor/generator in a high-speed flywheel-based uninterruptible power supply application is proposed in this paper. The feedforward controller takes most of the control output of the current regulator based on the machine model, and the PI controllers compensate the possible inaccuracies of the model to improve the performance and robustness of the complete control system. The machine current tracking error caused by parameter inaccuracy in the model-based controller is mathematically analyzed and utilized to dynamically compensate the estimated flux linkage to eliminate the steady-state error in current regulation. Stability analysis is also presented, and it can be seen that the regulation performance and robustness of the system are improved by the proposed hybrid controller. Simulation and experimental results consisting of a flywheel energy storage system validates the performance of the controller.      

Elasto-plastic finite element analysis

An elasto-plastic finite element small displacement procedure to predict the behaviour of structures under cyclic loads is presented. The solution combines incremental procedure with correction for equilibrium and iterative scheme. Applications are made for a rectangular strip and a notched bar under cyclic axial loads. Flow theory of plasticity with either isotropic hardening or kinematic linear hardening is used.