Abstract: This paper describes an experimental, theoretical
model and numerical study of concentrated vortex flow past a sphere
in a hydraulic check valve. The phenomenon of the rotation of the
ball around the axis of the device through which liquid flows has
been found. That is, due to the rotation of the sphere in the check
valve vibration is caused. We observe the rotation of the sphere
around the longitudinal axis of the check valve. This rotation is
induced by a vortex shedding from the sphere. We will discuss
computational simulation and experimental investigations of this
strong sphere rotation. The frequency of the sphere vibration and
interaction with the check valve wall has been measured as a function
of the wide range Reynolds Number. The validity of the
computational simulation and of the assumptions on which it is based
has been proved experimentally. This study demonstrates the
possibility to control the vibrations in a hydraulic system and proves
to be very effective suppression of the self-excited vibration.
Abstract: We developed a method based on quasi-molecular
modelling to simulate the fall of water drops on horizontally smooth
and rough surfaces. Each quasi-molecule was a group of particles
that interacted in a fashion entirely analogous to classical Newtonian
molecular interactions. When a falling water droplet was simulated at
low impact velocity on both smooth and rough surfaces, the droplets
moved periodically (i.e. the droplets moved up and down for a
certain period, finally they stopped moving and reached a steady
state), spreading and recoiling without splash or break-up. Spreading
rates of falling water droplets increased rapidly as time increased
until the spreading rate reached its steady state at time t ~ 0.25 s for
rough surface and t ~ 0.40 s for smooth surface. The droplet height
above both surfaces decreased as time increased, remained constant
after the droplet diameter attained a maximum value and reached its
steady state at time t ~ 0.4 s. However, rough surface had higher
spreading rates of falling water droplets and lower height on the
surface than smooth one.
Abstract: Helical milling operations are used to generate or
enlarge boreholes by means of a milling tool. The bore diameter can be
adjusted through the diameter of the helical path. The kinematics of
helical milling on a three axis machine tool is analysed firstly. The
relationships between processing parameters, cutting tool geometry
characters with machined hole feature are formulated. The feed motion
of the cutting tool has been decomposed to plane circular feed and
axial linear motion. In this paper, the time varying cutting forces acted
on the side cutting edges and end cutting edges of the flat end cylinder
miller is analysed using a discrete method separately. These two
components then are combined to produce the cutting force model
considering the complicated interaction between the cutters and
workpiece. The time varying cutting force model describes the
instantaneous cutting force during processing. This model could be
used to predict cutting force, calculate statics deflection of cutter and
workpiece, and also could be the foundation of dynamics model and
predicting chatter limitation of the helical milling operations.
Abstract: The rate of production of main products of the Fischer-Tropsch reactions over Fe/HZSM5 bifunctional catalyst in a fixed bed reactor is investigated at a broad range of temperature, pressure, space velocity, H2/CO feed molar ratio and CO2, CH4 and water flow rates. Model discrimination and parameter estimation were performed according to the integral method of kinetic analysis. Due to lack of mechanism development for Fisher – Tropsch Synthesis on bifunctional catalysts, 26 different models were tested and the best model is selected. Comprehensive one and two dimensional heterogeneous reactor models are developed to simulate the performance of fixed-bed Fischer – Tropsch reactors. To reduce computational time for optimization purposes, an Artificial Feed Forward Neural Network (AFFNN) has been used to describe intra particle mass and heat transfer diffusion in the catalyst pellet. It is seen that products' reaction rates have direct relation with H2 partial pressure and reverse relation with CO partial pressure. The results show that the hybrid model has good agreement with rigorous mechanistic model, favoring that the hybrid model is about 25-30 times faster.
Abstract: Computer-based decision support (CDSS) systems can
deliver real patient care and increase chances of long-term survival in
areas of chronic disease management prone to poor control. One such
CDSS, for the management of warfarin, is described in this paper and
the outcomes shown. Data is derived from the running system and
show a performance consistently around 20% better than the
applicable guidelines.
Abstract: In the crack growth analysis, the Stress Intensity
Factor (SIF) is a fundamental prerequisite. In the present study, the
mode I stress intensity factor (SIF) of three-dimensional penny-
Shaped crack is obtained in an isotropic elastic cylindrical medium
with arbitrary dimensions under arbitrary loading at the top of the
cylinder, by the semi-analytical method based on the Rayleigh-Ritz
method. This method that is based on minimizing the potential
energy amount of the whole of the system, gives a very close results
to the previous studies. Defining the displacements (elastic fields) by
hypothetical functions in a defined coordinate system is the base of
this research. So for creating the singularity conditions at the tip of
the crack the appropriate terms should be found.
Abstract: Sol-gel method has been used to fabricate
nanocomposite films on glass substrates composed halloysite clay
mineral and nanocrystalline TiO2. The methodology for the synthesis
involves a simple chemistry method utilized nonionic surfactant
molecule as pore directing agent along with the acetic acid-based solgel
route with the absence of water molecules. The thermal treatment
of composite films at 450oC ensures elimination of organic material
and lead to the formation of TiO2 nanoparticles onto the surface of
the halloysite nanotubes. Microscopy techniques and porosimetry
methods used in order to delineate the structural characteristics of the
materials. The nanocomposite films produced have no cracks and
active anatase crystal phase with small crystallite size were deposited
on halloysite nanotubes. The photocatalytic properties for the new
materials were examined for the decomposition of the Basic Blue 41
azo dye in solution. These, nanotechnology based composite films
show high efficiency for dye’s discoloration in spite of different
halloysite quantities and small amount of halloysite/TiO2 catalyst
immobilized onto glass substrates. Moreover, we examined the
modification of the halloysite/TiO2 films with silver particles in order
to improve the photocatalytic properties of the films. Indeed, the
presence of silver nanoparticles enhances the discoloration rate of the
Basic Blue 41 compared to the efficiencies obtained for unmodified
films.
Abstract: A novel interpolation scheme to extend usable spectrum
and upconvert in high performance D/A converters is addressed in this
paper. By adjusting the pulse width of cycle and the production circuit
of code, the expansion code is a null code or complementary code that
is interpolation process. What the times and codes of interpolation
decide DAC works in one of a normal mode or multi-mixer mode
so that convert the input digital data signal into normal signal or a
mixed analog signal having a mixer frequency that is higher than the
data frequency. Simulation results show that the novel scheme and
apparatus most extend the usable frequency spectrum into fifth to
sixth Nyquist zone beyond conventional DACs.
Abstract: An experiment was performed with a 24.5 MeV 14N
beam on a 12C target in the cyclotron DC-60 located in Astana,
Kazakhstan, to study the elastic scattering of 14N on 12C; the
scattering was also analyzed at different energies for tracking the
phenomenon of remarkable structure at large angles. Its aims were to
extend the measurements to very large angles, and attempt to
uniquely identify the elastic scattering potential. Good agreement
between the theoretical and experimental data has been obtained with
suitable optical potential parameters. Optical model calculations with
l -dependent imaginary potentials were also applied to the data and
relatively good agreement was found.
Abstract: In this study, mechanically alloyed Al 2024 powder is
densified by conventional sintering and by equal channel angular
pressing (ECAP) with and without back pressure. The powder was
encapsulated in an aluminium can for consolidation through ECAP.
The properties obtained in the compacts by conventional sintering
route and by ECAP are compared. The effect of conventional
sintering and ECAP on consolidation behaviour of powder,
microstructure, density and hardness is discussed. Room temperature
back pressure aided ECAP results in nearly full denser (97% of its
theoretical density) compact at room temperature. NanoIndentation
technique was used to determine the modulus of the consolidated
compacts.
Abstract: Composting is the process in which municipal solid
waste (MSW) and other organic waste materials such as biosolids
and manures are decomposed through the action of bacteria and other
microorganisms into a stable granular material which, applied to
land, as soil conditioner. Microorganisms, especially those that are
able to degrade polymeric organic material have a key role in speed
up this process. The aim of this study has been established to
isolation of microorganisms with high ability to production
extracellular enzymes for degradation of natural polymers that are
exists in MSW for decreasing time of degradation phase. Our
experimental study for isolation designed in two phases: in first
phase we isolated degrading microorganism with selected media that
consist a special natural polymer such as cellulose, starch, lipids and
etc as sole source of carbon. In second phase we selected
microorganism that had high degrading enzyme production with
enzymatic assay for seed production. However, our findings in pilot
scale have indicated that usage of this microbial consortium had high
efficiency for decreasing degradation phase.
Abstract: Multicast transmissions allow an host (the source) to send only one flow bound for a group of hosts (the receivers). Any equipment eager to belong to the group may explicitly register itself to that group via its multicast router. This router will be given the responsibility to convey all information relating to the group to all registered hosts. However in an environment in which the final receiver or the source frequently moves, the multicast flows need particular treatment. This constitutes one of the multicast transmissions problems around which several proposals were made in the Mobile IPv6 case in general. In this article, we describe the problems involved in this IPv6 multicast mobility and the existing proposals for their resolution. Then architecture will be proposed aiming to satisfy and optimize these transmissions in the specific case of a mobile multicast receiver in NC-HMIPv6 environment.
Abstract: Two indica varieties, IR36 and ‘Suweon 258’ (“S”)
are middle-heading in southern Japan. 36U, also middle-heading, is
an isogenic line of IR36 carrying Ur1 (Undulate rachis-1) gene.
However, late-heading plants segregated in the F2 population from
the F1 of S × 36U, and so did in the following generations. The
concerning lateness gene is designated as Ex. From the F8 generation,
isogenic-line pair of early-heading and late-heading lines, denoted by
“E” (ex/ex) and “L” (Ex/Ex), were developed. Genetic analyses of
heading time were conducted, using F1s and F2s among L, E, S and
36U. The following inferences were drawn from the experimental
results: 1) L, and both of E and 36U harbor Ex and ex, respectively;
2) Besides Ex, S harbors an inhibitor gene to it, i.e. I-Ex which is a
novel finding of the present study. 3) Ex is a dominant allele at the
E1 locus.
Abstract: The daily increase of organic waste materials resulting
from different activities in the country is one of the main factors for
the pollution of environment. Today, with regard to the low level of
the output of using traditional methods, the high cost of disposal
waste materials and environmental pollutions, the use of modern
methods such as anaerobic digestion for the production of biogas has
been prevailing. The collected biogas from the process of anaerobic
digestion, as a renewable energy source similar to natural gas but
with a less methane and heating value is usable. Today, with the help
of technologies of filtration and proper preparation, access to biogas
with features fully similar to natural gas has become possible. At
present biogas is one of the main sources of supplying electrical and
thermal energy and also an appropriate option to be used in four
stroke engine, diesel engine, sterling engine, gas turbine, gas micro
turbine and fuel cell to produce electricity. The use of biogas for
different reasons which returns to socio-economic and environmental
advantages has been noticed in CHP for the production of energy in
the world. The production of biogas from the technology of anaerobic
digestion and its application in CHP power plants in Iran can not only
supply part of the energy demands in the country, but it can
materialize moving in line with the sustainable development. In this
article, the necessity of the development of CHP plants with biogas
fuels in the country will be dealt based on studies performed from the
economic, environmental and social aspects. Also to prove the
importance of the establishment of these kinds of power plants from
the economic point of view, necessary calculations has been done as
a case study for a CHP power plant with a biogas fuel.
Abstract: In recent years, a new numerical method has been
developed, the extended finite element method (X-FEM). The
objective of this work is to exploit the (X-FEM) for the treatment of
the fracture mechanics problems on 3D geometries, where we
showed the ability of this method to simulate the fatigue crack
growth into two cases: edge and central crack. In the results we
compared the six first natural frequencies of mode shapes uncracking
with the cracking initiation in the structure, and showed the stress
intensity factor (SIF) evolution function as crack size propagation
into structure, the analytical validation of (SIF) is presented. For to
evidence the aspects of this method, all result is compared between
FEA and X-FEM.
Abstract: This method decrease usage power (expenditure) in networks on chips (NOC). This method data coding for data transferring in order to reduces expenditure. This method uses data compression reduces the size. Expenditure calculation in NOC occurs inside of NOC based on grown models and transitive activities in entry ports. The goal of simulating is to weigh expenditure for encoding, decoding and compressing in Baseline networks and reduction of switches in this type of networks. KeywordsNetworks on chip, Compression, Encoding, Baseline networks, Banyan networks.
Abstract: This paper is concerned with the design and implementation of MICOSim, an event-driven simulator written in Java for evaluating the performance of Grid entities (users, brokers and resources) under different scenarios such as varying the numbers of users, resources and brokers and varying their specifications and employed strategies.
Abstract: This article discusses the questions concerning of creating small packet networks for energy companies with application of high voltage power line carrier equipment (PLC) with functionality of IP traffic transmission. The main idea is to create converged PLC links between substations and dispatching centers where packet data and voice are transmitted in one data flow. The article contents description of basic conception of the network, evaluation of voice traffic transmission parameters, and discussion of header compression techniques in relation to PLC links. The results of exploration show us, that convergent packet PLC links can be very useful in the construction of small packet networks between substations in remote locations, such as deposits or low populated areas.
Abstract: Today-s Voltage Regulator Modules (VRMs) face increasing design challenges as the number of transistors in microprocessors increases per Moore-s Law. These challenges have recently become even more demanding as microprocessors operate at sub voltage range at significantly high current. This paper presents a new multiphase topology with cell configuration for improved performance in low voltage and high current applications. A lab scale hardware prototype of the new topology was design and constructed. Laboratory tests were performed on the proposed converter and compared with a commercially available VRM. Results from the proposed topology exhibit improved performance compared to the commercially available counterpart.
Abstract: This paper presents a novel methodology for Maximum Power Point Tracking (MPPT) of a grid-connected 20 kW Photovoltaic (PV) system using neuro-fuzzy network. The proposed method predicts the reference PV voltage guarantying optimal power transfer between the PV generator and the main utility grid. The neuro-fuzzy network is composed of a fuzzy rule-based classifier and three Radial Basis Function Neural Networks (RBFNN). Inputs of the network (irradiance and temperature) are classified before they are fed into the appropriated RBFNN for either training or estimation process while the output is the reference voltage. The main advantage of the proposed methodology, comparing to a conventional single neural network-based approach, is the distinct generalization ability regarding to the nonlinear and dynamic behavior of a PV generator. In fact, the neuro-fuzzy network is a neural network based multi-model machine learning that defines a set of local models emulating the complex and non-linear behavior of a PV generator under a wide range of operating conditions. Simulation results under several rapid irradiance variations proved that the proposed MPPT method fulfilled the highest efficiency comparing to a conventional single neural network.