Abstract: Anti-symmetric wave propagation along the particle motion of the wedge waves is known as anti-symmetric flexural (ASF) modes which travel along the wedge tips of the mid-plane apex with a small truncation. This paper investigates the characteristics of the ASF modes propagation with the wedge tip crack. The simulation and experimental results obtained by a three-dimensional (3-D) finite element model explained the contact acoustic non-linear (CAN) behavior in explicit dynamics in ABAQUS and the ultrasonic non-destructive testing (NDT) method is used for defect detection. The effect of various parameters on its high and low-level conversion modes are known for complex reflections and transmissions involved with direct reflections and transmissions. The results are used to predict the location of crack through complex transmission and reflection coefficients.
Abstract: Overtopping is known as one the most important reasons for the failure of earth dams. In some cases, it has resulted in heavy damages and losses. Therefore, enhancing the safety of earth dams against overtopping has received much attention in the past four decades. In this paper, at first, the overtopping phenomena and its destructive consequences will be introduced. Then, overtopping failure mechanism of embankments will be described. Finally, different types of protection systems for stabilization of earth dams against overtopping will be presented. These include timber cribs, riprap and gabions, reinforced earth, roller compacted concrete, and the precast concrete blocks.
Abstract: Allowable-bearing capacity is the competency of soil to safely carries the pressure from the superstructure without experiencing a shear failure with accompanying excessive settlements. Ensuring a safe bearing pressure with respect to failure does not tolerate settlement of the foundation will be within acceptable limits. Therefore, settlement analysis should always be performed since most structures are settlement sensitive. When visualising the movement of a soil wedge in the bearing capacity criterion, both vertically and horizontally, it becomes clear that by confining the soil surrounding the foundation, both the bearing capacity and settlement values improve. In this study, two sizes of spread foundation were considered; (2×4) m and (3×5) m. These represent two real problem case studies of an existing building. The foundations were analysed in terms of dimension as well as position with respect to a confining wall (i.e., sheet piles on both sides). Assuming B is the least foundation dimension, the study comprised the analyses of three distances; (0.1 B), (0.5 B), and (0.75 B) between the sheet piles and foundations alongside three depths of confinement (0.5 B), (1 B), and (1.5 B). Nonlinear three-dimensional finite element analysis (ANSYS) was adopted to perform an analytical investigation on the behaviour of the two foundations contained by the case study. Results showed that confinement of foundations reduced the overall stresses near the foundation by 65% and reduced the vertical displacement by 90%. Moreover, the most effective distance between the confinement wall and the foundation was found to be 0.5 B.
Abstract: The main objective of the present article is to explore the state of mixed convection nanofluid flow of gyrotactic microorganisms from an isothermal vertical wedge in porous medium. In our pioneering investigation, the easiest possible boundary conditions have been employed, in other words when the temperature, the nanofluid and motile microorganisms’ density have been considered to be constant on the wedge wall. Adding motile microorganisms to the nanofluid tends to enhance microscale mixing, mass transfer, and improve the nanofluid stability. Upon the Oberbeck–Boussinesq approximation and non-similarity transmutation, the paradigm of nonlinear equations are obtained and tackled numerically by using the R.K. Gill and shooting methods to obtain the dimensionless velocity, temperature, nanoparticle concentration and motile microorganisms density together with the reduced Sherwood, Nusselt, and numbers. Bioconvection parameters have strong effect upon the motile microorganism, heat, and volume fraction of nanoparticle transport rates. In the case when bioconvection is neglected, the obtained computations were found in very good agreement with the previous published data.
Abstract: The effects of thermal radiation, Soret and Dufour
parameters on mixed convection and nanofluid flow over a stretching
sheet in the presence of a magnetic field are investigated. The flow is
subject to temperature dependent viscosity and a chemical reaction
parameter. It is assumed that the nanoparticle volume fraction at the
wall may be actively controlled. The physical problem is modelled
using systems of nonlinear differential equations which have been
solved numerically using a spectral relaxation method. In addition
to the discussion on heat and mass transfer processes, the velocity,
nanoparticles volume fraction profiles as well as the skin friction
coefficient are determined for different important physical parameters.
A comparison of current findings with previously published results
for some special cases of the problem shows an excellent agreement.
Abstract: The magnetohydrodynamic (MHD) Falkner-Skan
equations appear in study of laminar boundary layers flow over
a wedge in presence of a transverse magnetic field. The partial
differential equations of boundary layer problems in presence of
a transverse magnetic field are reduced to MHD Falkner-Skan
equation by similarity solution methods. This is a nonlinear ordinary
differential equation. In this paper, we solve this equation via
spectral collocation method based on Bessel functions of the first
kind. In this approach, we reduce the solution of the nonlinear
MHD Falkner-Skan equation to a solution of a nonlinear algebraic
equations system. Then, the resulting system is solved by Newton
method. We discuss obtained solution by studying the behavior
of boundary layer flow in terms of skin friction, velocity, various
amounts of magnetic field and angle of wedge. Finally, the results
are compared with other methods mentioned in literature. We can
conclude that the presented method has better accuracy than others.
Abstract: The influence of slot wedges permeability on the electromagnetic performance of three-phase permanent magnet synchronous machine is investigated in this paper. It is shown that the back-EMF waveform, electromagnetic torque and electromagnetic torque ripple are all significantly affected by slot wedges permeability. The paper presents an accurate analytical subdomain model and confirmed by finite-element analyses.
Abstract: The subject of this paper is the investigation of the
best efficiency design of a compressor diffuser applied in new
lightweight, ultra efficient micro-gas turbine engines for vehicles. The
Computational Fluid Dynamics (CFD) results are obtained utilizing
steady state simulations for a wedge and an ”oval” type pipe diffuser
in an effort to identify the beneficial effects of the pipe diffuser
design. The basic flow features are presented with particular focus
on the optimization of the pipe diffuser leading to higher efficiencies
for the compressor stage. The optimised pipe diffuser is designed to
exploit the 3D freedom enabled by Selective Laser Melting, hence
purposely involves an investigation of geometric characteristics that
do not follow the traditional diffuser concept.
Abstract: Fiber Reinforced Polymer (FRP) is a composite material with exceptional properties that are capable to replace conventional steel reinforcement in reinforced and pre-stressed concrete structures. However, the main obstacle for their wide use in pre-stressed concrete application is the anchorage system. Due to the weakness of FRP in the transverse direction, the pre-stressing capacity of FRP bars are limited. This paper investigates the modification of the conventional wedge anchorage system to be used for stressing of FRP bars in pre-stressed applications. Epoxy adhesive material with glass FRP (GFRP) bars and conventional steel wedge were used in this paper. The GFRP bars are encased with epoxy at the anchor zone and the wedge system was used in pull-out test. The results showed a loading capacity of 47.6 kN which is 69% of the bar ultimate capacity. Additionally, nylon wedge was made with the same dimensions of the steel wedge and tested for GFRP bars without epoxy layer. The nylon wedge showed a loading capacity of 19.7 kN which is only 28.5% of the ultimate bar capacity.
Abstract: This paper presents a fully Lagrangian coupled
Fluid-Structure Interaction (FSI) solver for simulations of
fluid-structure interactions, which is based on the Moving Particle
Semi-implicit (MPS) method to solve the governing equations
corresponding to incompressible flows as well as elastic structures.
The developed solver is verified by reproducing the high velocity
impact loads of deformable thin wedges with three different materials
such as mild steel, aluminium and tin during water entry. The present
simulation results for aluminium are compared with analytical solution
derived from the hydrodynamic Wagner model and linear Wan’s
theory. And also, the impact pressure and strain on the water entry
wedge with three different materials, such as mild steel, aluminium
and tin, are simulated and the effects of hydro-elasticity are discussed.
Abstract: This paper deals with the theoretical and numerical
investigation of magneto hydrodynamic boundary layer flow of a
nanofluid past a wedge shaped wick in heat pipe used for the cooling
of electronic components and different type of machines. To
incorporate the effect of nanoparticle diameter, concentration of
nanoparticles in the pure fluid, nanothermal layer formed around the
nanoparticle and Brownian motion of nanoparticles etc., appropriate
models are used for the effective thermal and physical properties of
nanofluids. To model the rotation of nanoparticles inside the base
fluid, microfluidics theory is used. In this investigation ethylene
glycol (EG) based nanofluids, are taken into account. The non-linear
equations governing the flow and heat transfer are solved by using a
very effective particle swarm optimization technique along with
Runge-Kutta method. The values of heat transfer coefficient are
found for different parameters involved in the formulation viz.
nanoparticle concentration, nanoparticle size, magnetic field and
wedge angle etc. It is found that, the wedge angle, presence of
magnetic field, nanoparticle size and nanoparticle concentration etc.
have prominent effects on fluid flow and heat transfer characteristics
for the considered configuration.
Abstract: We used high-precision Global Positioning System
(GPS) to geodetically constrain the motion of stations in the
Darjiling-Sikkim Himalayan (DSH) wedge and examine the
deformation at the Indian-Tibetan plate boundary using IGS
(International GPS Service) fiducial stations. High-precision GPS
based displacement and velocity field was measured in the DSH
between 1997 and 2009. To obtain additional insight north of the
Indo-Tibetan border and in the Darjiling-Sikkim-Tibet (DaSiT)
wedge, published velocities from four stations J037, XIGA, J029 and
YADO were also included in the analysis. India-fixed velocities or
the back-slip was computed relative to the pole of rotation of the
Indian Plate (Latitude 52.97 ± 0.22º, Longitude - 0.30 ± 3.76º, and
Angular Velocity 0.500 ± 0.008º/ Myr) in the DaSiT wedge.
Dislocation modelling was carried out with the back-slip to model the
best possible solution of a finite rectangular dislocation or the
causative fault based on dislocation theory that produced the
observed back-slip using a forward modelling approach. To find the
best possible solution, three different models were attempted. First,
slip along a single thrust fault, then two thrust faults and in finally,
three thrust faults were modelled to simulate the back-slip in the
DaSiT wedge. The three-fault case bests the measured displacements
and is taken as the best possible solution.
Abstract: One of the parameters that affect the performance of microwave absorbers is the shape of the absorbers. This paper shows the performance (reflection loss) of truncated pyramidal and truncated wedge microwave absorbers in the range frequency between 8.2 to 12.4 GHz (X-Band) in simulation. The material used is sugarcane bagasse (SCB) which is one of the new materials that used to fabricate the microwave absorber. The complex permittivity was measured using Agilent dielectric probe technique. The designs were simulated using CST Microwave Studio Software. The reflection losses between these two shapes were compared.
Abstract: CFRP (Carbon Fiber Reinforced Polymer) is mainly used as reinforcing material for degraded structures owing to its advantages including its non-corrodibility, high strength and lightweight properties. Recently, dedicated studies focused not only on its simple bonding but also on its tensioning. The tension necessary for prestressing requires the anchoring of multi-CFRP tendons with high capacity and the surface treatment of the CFRP tendons may also constitute an important issue according to the type of anchor. The wedge type, swage type or bonded type anchor can be used to anchor the CFRP tendon. The bonded type anchor presents the disadvantage to lengthen the length of the anchor due to the low bond strength of the CFRP tendon without surface treatment. This study intends to overcome this drawback through the application of a method enlarging the bond area at the end of the CFRP tendon. This method enlarges the bond area by splitting the end of the CFRP tendon along its length and can be applied when CFRP is produced by pultrusion. The application of this method shows that the mono-CFRP tendon and 3-multi CFRP tendon secured the anchor performance corresponding to the tensile performance of the CFRP tendon and that the 7-multi tendon secured anchor performance corresponding to 90% of the tensile strength due to the occurrence of buckling in the steel tube anchorage.
Abstract: Nowadays, in most radiotherapy departments, the commercial treatment planning systems (TPS) used to calculate dose distributions needs to be verified; therefore, quick, easy-to-use and low cost dose distribution algorithms are desirable to test and verify the performance of the TPS. In this paper, we put forth an analytical method to calculate the phantom scatter contribution and depth dose on the central axis based on the equivalent square concept. Then, this method was generalized to calculate the profiles at any depth and for several field shapes regular or irregular fields under symmetry and asymmetry photon beam conditions. Varian 2100 C/D and Siemens Primus Plus Linacs with 6 and 18 MV photon beam were used for irradiations. Percentage depth doses (PDDs) were measured for a large number of square fields for both energies, and for 45º wedges which were employed to obtain the profiles in any depth. To assess the accuracy of the calculated profiles, several profile measurements were carried out for some treatment fields. The calculated and measured profiles were compared by gamma-index calculation. All γ–index calculations were based on a 3% dose criterion and a 3 mm dose-to-agreement (DTA) acceptance criterion. The γ values were less than 1 at most points. However, the maximum γ observed was about 1.10 in the penumbra region in most fields and in the central area for the asymmetric fields. This analytical approach provides a generally quick and fairly accurate algorithm to calculate dose distribution for some treatment fields in conventional radiotherapy.
Abstract: Tea has several types of essential elements. Potassium,
magnesium and phosphorus are some examples of these elements.
Tea is widely used drink in Turkey, also some people puts a lemon
wedge to tea for different taste. In this study potassium, magnesium
and phosphorus contents after the hot water brewing of black and
green tea were determined by Optical Emission Spectroscopy (ICPOES).
Furthermore, how the lemon addition to teas affects the
concentrations of the potassium, magnesium and phosphorus
amount are investigated.
From the results, potassium, magnesium and phosphorus
concentrations are found as 3003.3, 597.1, 1167.2 ppm in black tea
and 3718.0, 3830.5, 376.4 ppm in green tea, respectively. After
lemon addition potassium, magnesium and phosphorus
concentrations are changed to 14930, 830.4, 1113.5 ppm in black tea
and 15460.0, 909.5, 1152.5 ppm in green tea, respectively.
It is seen that lemon addition affects some essential elements in
black and green Turkish teas.
Abstract: Laser interferometric methods have been utilized for the measurement of natural convection heat transfer from a heated vertical flat plate, in the investigation presented here. The study mainly aims at comparing two different fringe orientations in the wedge fringe setting of Mach-Zehnder interferometer (MZI), used for the measurements. The interference fringes are set in horizontal and vertical orientations with respect to the heated surface, and two different fringe analysis methods, namely the stepping method and the method proposed by Naylor and Duarte, are used to obtain the heat transfer coefficients. The experimental system is benchmarked with theoretical results, thus validating its reliability in heat transfer measurements. The interference fringe patterns are analyzed digitally using MATLAB 7 and MOTIC Plus softwares, which ensure improved efficiency in fringe analysis, hence reducing the errors associated with conventional fringe tracing. The work also discuss the relative merits and limitations of the two methods used.
Abstract: The aim of this study was to compare the
sensitometric properties of commonly used radiographic films
processed with chemical solutions in different workload hospitals.
The effect of different processing conditions on induced densities on
radiologic films was investigated. Two accessible double emulsions
Fuji and Kodak films were exposed with 11-step wedge and
processed with Champion and CPAC processing solutions. The
mentioned films provided in both workloads centers, high and low.
Our findings displays that the speed and contrast of Kodak filmscreen
in both work load (high and low) is higher than Fuji filmscreen
for both processing solutions. However there was significant
differences in films contrast for both workloads when CPAC solution
had been used (p=0.000 and 0.028). The results showed base plus
fog density for Kodak film was lower than Fuji. Generally Champion
processing solution caused more speed and contrast for investigated
films in different conditions and there was significant differences in
95% confidence level between two used processing solutions
(p=0.01). Low base plus fog density for Kodak films provide more
visibility and accuracy and higher contrast results in using lower
exposure factors to obtain better quality in resulting radiographs. In
this study we found an economic advantages since Champion
solution and Kodak film are used while it makes lower patient dose.
Thus, in a radiologic facility any change in film processor/processing
cycle or chemistry should be carefully investigated before
radiological procedures of patients are acquired.
Abstract: To investigate the applicability of the EDR-2 film for
clinical radiation dosimetry, percentage depth-doses, profiles and
distributions in open and dynamically wedged fields were measured
using film and compared with data from a Treatment Planning
system.The validity of the EDR2 film to measure dose in a plane
parallel to the beam was tested by irradiating 10 cm×10 cm and 4
cm×4 cm fields from a Siemens, primus linac with a 6MV beam and
a source-to-surface distance of 100 cm. The film was placed
Horizontally between solid water phantom blocks and marked
with pin holes at a depth of 10 cm from the incident beam surface.
The film measurement results, in absolute dose, were compared with
ion chamber measurements using a Welhoffer scanning water tank
system and Treatment Planning system. Our results indicate a
maximum underestimate of calculated dose of 8 % with Treatment
Planning system.
Abstract: This paper examines the forced convection flow of
incompressible, electrically conducting viscous fluid past a sharp
wedge in the presence of heat generation or absorption with an
applied magnetic field. The system of partial differential equations
governing Falkner - Skan wedge flow and heat transfer is first
transformed into a system of ordinary differential equations using
similarity transformations which is later solved using an implicit
finite - difference scheme, along with quasilinearization technique.
Numerical computations are performed for air (Pr = 0.7) and
displayed graphically to illustrate the influence of pertinent physical
parameters on local skin friction and heat transfer coefficients and,
also on, velocity and temperature fields. It is observed that the
magnetic field increases both the coefficients of skin friction and heat
transfer. The effect of heat generation or absorption is found to be
very significant on heat transfer, but its effect on the skin friction is
negligible. Indeed, the occurrence of overshoot is noticed in the
temperature profiles during heat generation process, causing the
reversal in the direction of heat transfer.