Abstract: Workload and resource management are two essential functions provided at the service level of the grid software infrastructure. To improve the global throughput of these software environments, workloads have to be evenly scheduled among the available resources. To realize this goal several load balancing strategies and algorithms have been proposed. Most strategies were developed in mind, assuming homogeneous set of sites linked with homogeneous and fast networks. However for computational grids we must address main new issues, namely: heterogeneity, scalability and adaptability. In this paper, we propose a layered algorithm which achieve dynamic load balancing in grid computing. Based on a tree model, our algorithm presents the following main features: (i) it is layered; (ii) it supports heterogeneity and scalability; and, (iii) it is totally independent from any physical architecture of a grid.
Abstract: Based on experimental data using accelerometry technology there was developed an analytical model that approximates human induced ground reaction forces in vertical, longitudinal and lateral directions ascending and descending the stairs. Proposed dynamic loading factors and corresponding phase shifts for the first five harmonics of continuous walking force history in case of stair ascend and descend. Into account is taken imperfectness of individual footfall forcing functions, differences between continuous walking force histories among individuals. There is proposed mean synthetic continuous walking force history that can be used in numerical simulations of human movement on the stairs.
Abstract: The main aim of the presented experiments is to
improve behaviour of sandwich structures under dynamic loading,
such as crash or explosion. Several cellular materials are widely used
as core of the sandwich structures and their properties influence
the response of the entire element under impact load. To optimize
their performance requires the characterisation of the core material
behaviour at high strain rates and identification of the underlying
mechanism. This work presents the study of high strain-rate
characteristics of a specific porous lightweight blast energy absorbing
foam using a Split Hopkinson Pressure Bar (SHPB) technique
adapted to perform tests on low strength materials. Two different
velocities, 15 and 30 m.s-1 were used to determine the strain
sensitivity of the material. Foams were designed using two types of
porous lightweight spherical raw materials with diameters of 30-
100 *m, combined with polymer matrix. Cylindrical specimens with
diameter of 15 mm and length of 7 mm were prepared and loaded
using a Split Hopkinson Pressure Bar apparatus to assess the relation
between the composition of the material and its shock wave
attenuation capacity.
Abstract: Hierarchical Mobile IPv6 (HMIPv6) was designed to
support IP micro-mobility management in the Next Generation
Networks (NGN) framework. The main design behind this protocol is
the usage of Mobility Anchor Point (MAP) located at any level router
of network to support hierarchical mobility management. However,
the distance MAP selection in HMIPv6 causes MAP overloaded and
increase frequent binding update as the network grows. Therefore, to
address the issue in designing MAP selection scheme, we propose a
dynamic load control mechanism integrates with a speed detection
mechanism (DMS-DLC). From the experimental results we obtain
that the proposed scheme gives better distribution in MAP load and
increase handover speed.
Abstract: Many footbridges have natural frequencies that
coincide with the dominant frequencies of the pedestrian-induced
load and therefore they have a potential to suffer excessive vibrations
under dynamic loads induced by pedestrians. Some of the design
standards introduce load models for pedestrian loads applicable for
simple structures. Load modeling for more complex structures, on the
other hand, is most often left to the designer. The main focus of this
paper is on the human induced forces transmitted to a footbridge and
on the ways these loads can be modeled to be used in the dynamic
design of footbridges. Also design criteria and load models proposed
by widely used standards were introduced and a comparison was
made. The dynamic analysis of the suspension bridge in Kolin in the
Czech Republic was performed on detailed FEM model using the
ANSYS program system. An attempt to model the load imposed by a
single person and a crowd of pedestrians resulted in displacements
and accelerations that are compared with serviceability criteria.
Abstract: This paper deals with a numerical analysis of the
transient response of composite beams with strain rate dependent
mechanical properties by use of a finite difference method. The
equations of motion based on Timoshenko beam theory are derived.
The geometric nonlinearity effects are taken into account with von
Kármán large deflection theory. The finite difference method in
conjunction with Newmark average acceleration method is applied to
solve the differential equations. A modified progressive damage
model which accounts for strain rate effects is developed based on
the material property degradation rules and modified Hashin-type
failure criteria and added to the finite difference model. The
components of the model are implemented into a computer code in
Mathematica 6. Glass/epoxy laminated composite beams with
constant and strain rate dependent mechanical properties under
dynamic load are analyzed. Effects of strain rate on dynamic
response of the beam for various stacking sequences, load and
boundary conditions are investigated.