Abstract: In built-up structures, one of the effective ways of
dissipating unwanted vibration is to exploit the occurrence of slip at
the interfaces of structural laminates. The present work focuses on
the dynamic analysis of welded structures. A mathematical
formulation has been developed for the mechanism of slip damping
in layered and welded mild steel beams with unequal thickness
subjected to both periodic and non-periodic forces. It is observed that
a number of vital parameters such as; thickness ratio, pressure
distribution characteristics, relative slip and kinematic co-efficient of
friction at the interfaces, nature of exciting forces, length and
thickness of the beam specimen govern the damping characteristics of
these structures. Experimental verification has been carried out to
validate the analysis and study the effect of these parameters. The
developed damping model for the structure is found to be in fairly
good agreement with the measured data. Finally, the results of the
analysis are discussed and rationalized.
Abstract: Response surface methodology with Box–Benhken (BB) design of experiment approach has been utilized to study the mechanism of interface slip damping in layered and jointed tack welded beams with varying surface roughness. The design utilizes the initial amplitude of excitation, tack length and surface roughness at the interfaces to develop the model for the logarithmic damping decrement of the layered and jointed welded structures. Statistically designed experiments have been performed to estimate the coefficients in the mathematical model, predict the response, and check the adequacy of the model. Comparison of predicted and experimental response values outside the design conditions have shown good correspondence, implying that empirical model derived from response surface approach can be effectively used to describe the mechanism of interface slip damping in layered and jointed tack welded structures.
Abstract: The paper presents the results of microhardness and
microstructure of low carbon steel surface melted using carbon
dioxide laser with a wavelength of 10.6μm and a maximum output
power of 2000W. The processing parameters such as the laser power,
and the scanning rate were investigated in this study. After surface
melting two distinct regions formed corresponding to the melted zone
MZ, and the heat affected zone HAZ. The laser melted region
displayed a cellular fine structures while the HAZ displayed
martensite or bainite structure. At different processing parameters,
the original microstructure of this steel (Ferrite+Pearlite) has been
transformed to new phases of martensitic and bainitic structures. The
fine structure and the high microhardness are evidence of the high
cooling rates which follow the laser melting. The melting pool and
the transformed microstructure in the laser surface melted region of
carbon steel showed clear dependence on laser power and scanning
rate.
Abstract: This paper highlights the importance of the selection
of the building-s wall material,and the shortcomings of the most
commonly used framed structures with masonry infills .The
objective of this study is investigating the behavior of infill walls as
structural components in existing structures.Structural infill walls are
very important in structural behavior under earthquake effects.
Structural capacity under the effect of earthquake,displacement and
relative story displacement are affected by the structural irregularities
.The presence of nonstructural masonry infill walls can modify
extensively the global seismic behavior of framed buildings .The
stability and integrity of reinforced concrete frames are enhanced by
masonry infill walls. Masonry infill walls alter displacement and
base shear of the frame as well. Short columns have great
importance during earthquakes,because their failure may lead to
additional structural failures and result in total building collapse.
Consequently the effects of short columns are considered in this
study.
Abstract: Most buildings have been using anchor bolts
commonly for installing outdoor advertising structures. Anchor bolts
of common carbon steel are widely used and often installed
indiscriminately by inadequate installation standards. In the area
where strong winds frequently blow, falling accidents of outdoor
advertising structures can occur and cause a serious disaster, which is
very dangerous and to be prevented. In this regard, the development of
high-performance anchor bolts is urgently required. In the present
study, 25Cr-8Ni-1.5Si-1Mn-0.4C alloy was produced by traditional
vacuum induction melting (VIM) for the application of anchor bolt.
The alloy composition is revealed as a duplex microstructure from
thermodynamic phase analysis by FactSage® and confirmed by
metallographic experiment. Addition of Nitrogen to the alloy was
found to reduce the ferritic phase domain and significantly increase the
hardness and the tensile strength. Microstructure observation revealed
mixed structure of austenite and ferrite with fine carbide distributed
along the grain and phase boundaries.
Abstract: In the stadium structure, the significant dynamic
responses such as resonance or similar behavior can be occurred by
spectator rhythmical activities. Thus, accurate analysis and precise
investigation of stadium structure that is subjected to dynamic loads
are required for practical design and serviceability check of stadium
structures. Moreover, it is desirable to measure and analyze the
dynamic loads of spectator activities because these dynamic loads can
not be easily expressed in numerical formula. In this study, various
dynamic loads induced by spectator movements are measured and
analyzed. These dynamic loads induced by spectators movement of
stadium structure can be classified into the impact load and the
periodic load. These dynamic loads can be expressed as Fourier
harmonic load. And, these dynamic loads could be applied for the
accurate vibration analysis of a stadium structure.
Abstract: Turbulence studies were made in the wake of a rotating
circular cylinder in a uniform free stream. The interest was to
examine the turbulence properties at the suppression of periodicity in
vortex formation process. An experimental study of the turbulent near
wake of a rotating circular cylinder was made at a Reynolds number
of 9000 for velocity ratios, λ between 0 and 2.7. Hot-wire
anemometry and particle image velocimetry results indicate that the
rotation of the cylinder causes significant changes in the vortical
activities. The turbulence quantities are getting smaller as λ increases
due to suppression of coherent vortex structures.
Abstract: The importance for manipulating an incorporated
scaffold and directing cell behaviors is well appreciated for tissue
engineering. Here, we developed newly nano-topographic oxidized
silicon nanosponges capable of being various chemical modifications
to provide much insight into the fundamental biology of how cells
interact with their surrounding environment in vitro. A wet etching
technique is exerted to allow us fabricated the silicon nanosponges in a
high-throughput manner. Furthermore, various organo-silane
chemicals enabled self-assembled on the surfaces by vapor deposition.
We have found that Chinese hamster ovary (CHO) cells displayed
certain distinguishable morphogenesis, adherent responses, and
biochemical properties while cultured on these chemical modified
nano-topographic structures in compared with the planar oxidized
silicon counterparts, indicating that cell behaviors can be influenced
by certain physical characteristic derived from nano-topography in
addition to the hydrophobicity of contact surfaces crucial for cell
adhesion and spreading. Of particular, there were predominant
nano-actin punches and slender protrusions formed while cells were
cultured on the nano-topographic structures. This study shed potential
applications of these nano-topographic biomaterials for controlling
cell development in tissue engineering or basic cell biology research.
Abstract: Few studies have been conducted on polymeric strip
and the behavior of soil retaining walls. This paper will present the
effect of frequency on the dynamic behavior of reinforced soil
retaining walls with polymeric strips. The frequency content
describes how the amplitude of a ground motion is distributed among
different frequencies. Since the frequency content of an earthquake
motion will strongly influence the effects of that motion, the
characterization of the motion cannot be completed without the
consideration of its frequency content. The maximum axial force of
reinforcements and horizontal displacement of the reinforced walls
are focused in this research. To clarify the dynamic behavior of
reinforced soil retaining walls with polymeric strips, a numerical
modeling using Finite Difference Method is benefited. As the results
indicate, the frequency of input base acceleration has an important
effect on the behavior of these structures. Because of resonant in the
system, where the frequency of the input dynamic load is equal to the
natural frequency of the system, the maximum horizontal
displacement and the maximum axial forces in polymeric strips is
occurred. Moreover, they were to increase the structure flexibility
because of the main advantages of polymeric strips; i.e. being simple
method of construction, having a homogeneous behavior with soils,
and possessing long durability, which are of great importance in
dynamic analysis.
Abstract: Polyurethane foams (PUF) were formed by a chemical
reaction of polyol and isocyanate. The polyol was manufactured by
ring-opening hydrolysis of epoxidized soybean oil in the presence of
phosphoric acid under varying experimental conditions. Other
factors in the foam formulation such as water content and surfactant
were kept constant. The effect of the amount of solvents, phosphoric
acid, and their derivates in the foam formulation on the properties of
polyurethane foams were studied. The properties of the material were
measured via a number of parameters, which are water content of
prepared polyol, polymer density and cellular structures.
Abstract: Sedimentation formation is a complex hydraulic phenomenon that has emerged as a major operational and maintenance consideration in modern hydraulic engineering in general and river engineering in particular. Sediments accumulation along the river course and their eventual storage in a form of islands affect water intake in the canal systems that are fed by the storage reservoirs. Without proper management, sediment transport can lead to major operational challenges in water distribution system of arid regions like the Dez and Hamidieh command areas. The paper aims to investigate sedimentation in the Western Canal of Dez Diversion Weir using the SHARC model and compare the results with the two intake structures of the Hamidieh dam in Iran using SSIIM model. The objective was to identify the factors which influence the process, check reliability of outcome and provide ways in which to mitigate the implications on operation and maintenance of the structures. Results estimated sand and silt bed loads concentrations to be 193 ppm and 827ppm respectively. This followed ,ore or less similar pattern in Hamidieh where the sediment formation impeded water intake in the canal system. Given the available data on average annual bed loads and average suspended sediment loads of 165ppm and 837ppm in the Dez, there was a significant statistical difference (16%) between the sand grains, whereas no significant difference (1.2%) was find in the silt grain sizes. One explanation for such finding being that along the 6 Km river course there was considerable meandering effects which explains recent shift in the hydraulic behavior along the stream course under investigation. The sand concentration in downstream relative to present state of the canal showed a steep descending curve. Sediment trapping on the other hand indicated a steep ascending curve. These occurred because the diversion weir was not considered in the simulation model. The comparative study showed very close similarities in the results which explains the fact that both software can be used as accurate and reliable analytical tools for simulation of the sedimentation in hydraulic engineering.
Abstract: Dextran is a D-glucose polymer which is produced by
Leuconostoc mesenteroides grown in a sucrose-rich media. The
organism was obtained from the Persian Type Culture Collection
(PTCC) and was transferred in MRS broth medium at 30°C and pH
6.8 for 24 h. After preparation of inoculums, organisms were
inoculated into five liquid fermentation media containing either
molasses or cheese whey or different combinations of cheese whey
and molasses. After certain fermentation period, the produced
dextran was separated and dried. Dextran yield was calculated and
significant differences in different media were observed.
Furthermore, FT-IR analysis was performed and the results showed
that there were no significant differences in the produced dextran
structures.
Abstract: Retinal vascularity assessment plays an important role in diagnosis of ophthalmic pathologies. The employment of digital images for this purpose makes possible a computerized approach and has motivated development of many methods for automated vascular tree segmentation. Metrics based on contingency tables for binary classification have been widely used for evaluating performance of these algorithms and, concretely, the accuracy has been mostly used as measure of global performance in this topic. However, this metric shows very poor matching with human perception as well as other notable deficiencies. Here, a new similarity function for measuring quality of retinal vessel segmentations is proposed. This similarity function is based on characterizing the vascular tree as a connected structure with a measurable area and length. Tests made indicate that this new approach shows better behaviour than the current one does. Generalizing, this concept of measuring descriptive properties may be used for designing functions for measuring more successfully segmentation quality of other complex structures.
Abstract: The competitive learning is an adaptive process in
which the neurons in a neural network gradually become sensitive to
different input pattern clusters. The basic idea behind the Kohonen-s
Self-Organizing Feature Maps (SOFM) is competitive learning.
SOFM can generate mappings from high-dimensional signal spaces
to lower dimensional topological structures. The main features of this
kind of mappings are topology preserving, feature mappings and
probability distribution approximation of input patterns. To overcome
some limitations of SOFM, e.g., a fixed number of neural units and a
topology of fixed dimensionality, Growing Self-Organizing Neural
Network (GSONN) can be used. GSONN can change its topological
structure during learning. It grows by learning and shrinks by
forgetting. To speed up the training and convergence, a new variant
of GSONN, twin growing cell structures (TGCS) is presented here.
This paper first gives an introduction to competitive learning, SOFM
and its variants. Then, we discuss some GSONN with fixed
dimensionality, which include growing cell structures, its variants
and the author-s model: TGCS. It is ended with some testing results
comparison and conclusions.
Abstract: This paper proposes a framework for product
development including hardware and software components. It
provides separation of hardware dependent software, modifications of
current product development process, and integration of software
modules with existing product configuration models and assembly
product structures. In order to decide the dependent software, the
framework considers product configuration modules and engineering
changes of associated software and hardware components. In order to
support efficient integration of the two different hardware and
software development, a modified product development process is
proposed. The process integrates the dependent software development
into product development through the interchanges of specific product
information. By using existing product data models in Product Data
Management (PDM), the framework represents software as modules
for product configurations and software parts for product structure.
The framework is applied to development of a robot system in order to
show its effectiveness.
Abstract: The model-based approach to user interface design
relies on developing separate models capturing various aspects about
users, tasks, application domain, presentation and dialog structures.
This paper presents a task modeling approach for user interface
design and aims at exploring mappings between task, domain and
presentation models. The basic idea of our approach is to identify
typical configurations in task and domain models and to investigate
how they relate each other. A special emphasis is put on applicationspecific
functions and mappings between domain objects and
operational task structures. In this respect, we will address two
layers in task decomposition: a functional (planning) layer and an
operational layer.
Abstract: IT infrastructures are becoming more and more
difficult. Therefore, in the first industrial IT systems, the P2P
paradigm has replaced the traditional client server and methods of
self-organization are gaining more and more importance. From the
past it is known that especially regular structures like grids may
significantly improve the system behavior and performance. This
contribution introduces a new algorithm based on a biologic
analogue, which may provide the growth of several regular structures
on top of anarchic grown P2P- or social network structures.
Abstract: This research explores the links between physical
development and transportation infrastructure around Kumasi,
Ghana. It utilizes census data as well as fieldwork and interviews
carried out during July and December 2005. The results suggest that
there is a weak association between transportation investments and
physical development, and that recent housing has generally occurred
in poorly accessible locations. Road investments have generally
followed physical expansion rather than the reverse. Hence policies
designed to manage the fast growth now occurring around Ghanaian
cities should not focus exclusively on improving transportation
infrastructure but also strengthening the underlying the traditional
land management structures and the official land administrative
institutions that operate within those structures.
Abstract: The objective of our work is to develop a new approach for discovering knowledge from a large mass of data, the result of applying this approach will be an expert system that will serve as diagnostic tools of a phenomenon related to a huge information system. We first recall the general problem of learning Bayesian network structure from data and suggest a solution for optimizing the complexity by using organizational and optimization methods of data. Afterward we proposed a new heuristic of learning a Multi-Entities Bayesian Networks structures. We have applied our approach to biological facts concerning hereditary complex illnesses where the literatures in biology identify the responsible variables for those diseases. Finally we conclude on the limits arched by this work.
Abstract: The recent drive for use of performance-based methodologies in design and assessment of structures in seismic areas has significantly increased the demand for the development of reliable nonlinear inelastic static pushover analysis tools. As a result, the adaptive pushover methods have been developed during the last decade, which unlike their conventional pushover counterparts, feature the ability to account for the effect that higher modes of vibration and progressive stiffness degradation might have on the distribution of seismic storey forces. Even in advanced pushover methods, little attention has been paid to the Unsymmetric structures. This study evaluates the seismic demands for three dimensional Unsymmetric-Plan buildings determined by the Displacement-based Adaptive Pushover (DAP) analysis, which has been introduced by Antoniou and Pinho [2004]. The capability of DAP procedure in capturing the torsional effects due to the irregularities of the structures, is investigated by comparing its estimates to the exact results, obtained from Incremental Dynamic Analysis (IDA). Also the capability of the procedure in prediction the seismic behaviour of the structure is discussed.