Abstract: Displacement measurement was conducted on compact normal and shear specimens made of acrylic homogeneous material subjected to mixed-mode loading by digital image correlation. The intelligent hybrid method proposed by Nishioka et al. was applied to the stress-strain analysis near the crack tip. The accuracy of stress-intensity factor at the free surface was discussed from the viewpoint of both the experiment and 3-D finite element analysis. The surface images before and after deformation were taken by a CMOS camera, and we developed the system which enabled the real time stress analysis based on digital image correlation and inverse problem analysis. The great portion of processing time of this system was spent on displacement analysis. Then, we tried improvement in speed of this portion. In the case of cracked body, it is also possible to evaluate fracture mechanics parameters such as the J integral, the strain energy release rate, and the stress-intensity factor of mixed-mode. The 9-points elliptic paraboloid approximation could not analyze the displacement of submicron order with high accuracy. The analysis accuracy of displacement was improved considerably by introducing the Newton-Raphson method in consideration of deformation of a subset. The stress-intensity factor was evaluated with high accuracy of less than 1% of the error.
Abstract: This paper presents the influence of distributed generation (DG) on congestion and locational marginal price (LMP) in an optimal power flow (OPF) based wholesale electricity market. The problem of optimal placement to manage congestion and reduce LMP is formulated for the objective of social welfare maximization. From competitive electricity market standpoint, DGs have great value when they reduce load in particular locations and at particular times when feeders are heavily loaded. The paper lies on the groundwork that solution to optimal mix of generation and transmission resources can be achieved by addressing congestion and corresponding LMP. Obtained as lagrangian multiplier associated with active power flow equation for each node, LMP gives the short run marginal cost (SRMC) of electricity. Specific grid locations are examined to study the influence of DG penetration on congestion and corresponding shadow prices. The influence of DG on congestion and locational marginal prices has been demonstrated in a modified IEEE 14 bus test system.
Abstract: Thyroid dysfunction is one of the most frequently
reported complications of chronic blood transfusion therapy in patients with beta-thalassemia major (BTM). However, the occurrence of thyroid dysfunction and its possible association with
iron overload in BTM patients is still under debate. Therefore, this
study aimed to investigate the status of thyroid functions and iron overload in adolescent and young adult patients with BTM in Jordan population. Thirty six BTM patients aged 12-28 years and matched controls were included in this study. All patients have been receiving frequent blood transfusion to maintain pretransfusion hemoglobin
concentration above 10 g dl-1 and deferoxamine at a dose of 45 mg kg-1 day-1 (8 h, 5-7 days/week) by subcutaneous infusion. Blood
samples were drawn from patients and controls. The status of thyroid functions and iron overload was evaluated by measurements of serum
free thyroxine (FT4), triiodothyronine (FT3), thyrotropin (TSH) and
serum ferritin level. A number of some hematological and
biochemical parameters were also measured. It was found that hematocrit, serum ferritin, hemoglobin, FT3 and zinc, copper mean values were significantly higher in the patients than in the controls (P< 0.05). On other hand, leukocyte, FT4 and TSH mean values were
similar to that of the controls. In addition, our data also indicated that
all of the above examined parameters were not significantly affected
by the patient-s age and gender. Deferoxamine approach for removing excess iron from our BTM patient did not normalize the
values of serum ferritin, copper and zinc, suggesting poor compliance
with deferoxamine chelation therapy. Thus, we recommend the use
of a combination of deferoxamine and deferiprone to reduce the risk
of excess of iron in our patients. Furthermore, thyroid dysfunction
appears to be a rare complication, because our patients showed
normal mean levels for serum TSH and FT4. However, high mean
levels of serum ferritin, zinc, copper might be seen as potential risk
factors for initiation and development of thyroid dysfunctions and
other diseases. Therefore, further studies must be carried out at
yearly intervals with large sample number, to detect subclinical
thyroid dysfunction cases.
Abstract: This paper proposes a new optimal feedback controller
for voltage source converters VSC's, for current regulated voltage
source converters, which allows compensate the harmonics of current
produced by nonlinear loads and load reactive power. The aim of the
present paper is to describe a novel switching signal generation
technique called optimal controller which guarantees that the injected
currents follow the reference currents determined by the
compensation strategy, with the smallest possible tracking error and
fixed switching frequency. It is compared with well-known
hysteresis current controller HCC. The validity of presented method
and its comparison with HCC is studied through simulation results.
Abstract: Middle-gate is located in Hasankeyf, Batman dating
back to 1800 BC and is one of the important historical structures in
Turkey. The ancient structure has suffered major structural cracks
due to aging as well as lateral pressure of a cracked rock which is
predicted to be about 100 tons. The existing support system was
found to be inadequate to support the load especially after a recent
rock fall in the close vicinity. Concerns were increased since the
existing support system that is integral with a damaged and cracked
gate wall needed to be replaced by a new support system. The
replacement process must be carefully monitored by crackmeters and
control mechanisms should be integrated to prevent cracks to expand
while the same crack width needs to be maintained after the
operation. The control system and actions taken during the
intervention are explained in this paper.
Abstract: Evolution of one-dimensional electron system under
high-energy-density (HED) conditions is investigated, using the
principle of least-action and variational method. In a single-mode
modulation model, the amplitude and spatial wavelength of the
modulation are chosen to be general coordinates. Equations of motion
are derived by considering energy conservation and force balance.
Numerical results show that under HED conditions, electron density
modulation could exist. Time dependences of amplitude and
wavelength are both positively related to the rate of energy input.
Besides, initial loading speed has a significant effect on modulation
amplitude, while wavelength relies more on loading duration.
Abstract: This research work proposed a study of fruit bruise detection by means of a biospeckle method, selecting the papaya fruit (Carica papaya) as testing body. Papaya is recognized as a fruit of outstanding nutritional qualities, showing high vitamin A content, calcium, carbohydrates, exhibiting high popularity all over the world, considering consumption and acceptability. The commercialization of papaya faces special problems which are associated to bruise generation during harvesting, packing and transportation. Papaya is classified as climacteric fruit, permitting to be harvested before the maturation is completed. However, by one side bruise generation is partially controlled once the fruit flesh exhibits high mechanical firmness. By the other side, mechanical loads can set a future bruise at that maturation stage, when it can not be detected yet by conventional methods. Mechanical damages of fruit skin leave an entrance door to microorganisms and pathogens, which will cause severe losses of quality attributes. Traditional techniques of fruit quality inspection include total soluble solids determination, mechanical firmness tests, visual inspections, which would hardly meet required conditions for a fully automated process. However, the pertinent literature reveals a new method named biospeckle which is based on the laser reflectance and interference phenomenon. The laser biospeckle or dynamic speckle is quantified by means of the Moment of Inertia, named after its mechanical counterpart due to similarity between the defining formulae. Biospeckle techniques are able to quantify biological activities of living tissues, which has been applied to seed viability analysis, vegetable senescence and similar topics. Since the biospeckle techniques can monitor tissue physiology, it could also detect changes in the fruit caused by mechanical damages. The proposed technique holds non invasive character, being able to generate numerical results consistent with an adequate automation. The experimental tests associated to this research work included the selection of papaya fruit at different maturation stages which were submitted to artificial mechanical bruising tests. Damages were visually compared with the frequency maps yielded by the biospeckle technique. Results were considered in close agreement.
Abstract: The abnormal increase in the number of applications available for download in Android markets is a good indication that they are being reused. However, little is known about their real reusability potential. A considerable amount of these applications is reported as having a poor quality or being malicious. Hence, in this paper, an approach to measure the reusability potential of classes in Android applications is proposed. The approach is not meant specifically for this particular type of applications. Rather, it is intended for Object-Oriented (OO) software systems in general and aims also to provide means to discard the classes of low quality and defect prone applications from being reused directly through inheritance and instantiation. An empirical investigation is conducted to measure and rank the reusability potential of the classes of randomly selected Android applications. The results obtained are thoroughly analyzed in order to understand the extent of this potential and the factors influencing it.
Abstract: A three-dimensional finite element modeling for austenitic stainless steel AISI 304 annealed condition sheets of 1.0 mm thickness are developed using ABAQUS® software. This includes spot welded and weld bonded joints models. Both models undergo thermal heat caused by spot welding process and then are subjected to axial load up to the failure point. The properties of elastic and plastic regions, modulus of elasticity, fracture limit, nugget and heat affected zones are determined. Complete loaddisplacement curve for each joining model is obtained and compared with the experiment data and with the finite element models without including the effect of thermal process. In general, the results obtained for both spot welded and weld-bonded joints affected by thermal process showed an excellent agreement with the experimental data.
Abstract: Voltage stability has become an important issue to many power systems around the world due to the weak systems and long line on power system networks. In this paper, MATLAB load flow program is applied to obtain the weak points in the system combined with finding the voltage stability limit. The maximum permissible loading of a system, within the voltage stability limit, is usually determined. The methods for varying tap ratio (using tap changing transformer) and applying different values of shunt capacitor injection to improve the voltage stability within the limit are also provided.
Abstract: This paper presents an analytical method to solve
governing consolidation parabolic partial differential equation (PDE)
for inelastic porous Medium (soil) with consideration of variation of
equation coefficient under cyclic loading. Since under cyclic loads,
soil skeleton parameters change, this would introduce variable
coefficient of parabolic PDE. Classical theory would not rationalize
consolidation phenomenon in such condition. In this research, a
method based on time space mapping to a virtual time space along
with superimposing rule is employed to solve consolidation of
inelastic soils in cyclic condition. Changes of consolidation
coefficient applied in solution by modification of loading and
unloading duration by introducing virtual time. Mapping function is
calculated based on consolidation partial differential equation results.
Based on superimposing rule a set of continuous static loads in
specified times used instead of cyclic load. A set of laboratory
consolidation tests under cyclic load along with numerical
calculations were performed in order to verify the presented method.
Numerical solution and laboratory tests results showed accuracy of
presented method.
Abstract: Optimization and control of reactive power
distribution in the power systems leads to the better operation of the
reactive power resources. Reactive power control reduces
considerably the power losses and effective loads and improves the
power factor of the power systems. Another important reason of the
reactive power control is improving the voltage profile of the power
system. In this paper, voltage and reactive power control using
Neural Network techniques have been applied to the 33 shines-
Tehran Electric Company. In this suggested ANN, the voltages of PQ
shines have been considered as the input of the ANN. Also, the
generators voltages, tap transformers and shunt compensators have
been considered as the output of ANN. Results of this techniques
have been compared with the Linear Programming. Minimization of
the transmission line power losses has been considered as the
objective function of the linear programming technique. The
comparison of the results of the ANN technique with the LP shows
that the ANN technique improves the precision and reduces the
computation time. ANN technique also has a simple structure and
this causes to use the operator experience.
Abstract: In this paper, we propose an easily computable proximity index for predicting voltage collapse of a load bus using only measured values of the bus voltage and power; Using these measurements a polynomial of fourth order is obtained by using LES estimation algorithms. The sum of the absolute values of the polynomial coefficient gives an idea of the critical bus. We demonstrate the applicability of our proposed method on 6 bus test system. The results obtained verify its applicability, as well as its accuracy and the simplicity. From this indicator, it is allowed to predict the voltage instability or the proximity of a collapse. Results obtained by the PV curve are compared with corresponding values by QV curves and are observed to be in close agreement.
Abstract: In this study, a frame work for verification of famous seismic codes is utilized. To verify the seismic codes performance, damage quantity of RC frames is compared with the target performance. Due to the randomness property of seismic design and earthquake loads excitation, in this paper, fragility curves are developed. These diagrams are utilized to evaluate performance level of structures which are designed by the seismic codes. These diagrams further illustrate the effect of load combination and reduction factors of codes on probability of damage exceedance. Two types of structures; very high important structures with high ductility and medium important structures with intermediate ductility are designed by different seismic codes. The Results reveal that usually lower damage ratio generate lower probability of exceedance. In addition, the findings indicate that there are buildings with higher quantity of bars which they have higher probability of damage exceedance. Life-cycle cost analysis utilized for comparison and final decision making process.
Abstract: Since the last two decades, container transportation
system has been faced under increasing development. This fact
shows the importance of container transportation system as a key role
of container terminals to link between sea and land. Therefore, there
is a continuous need for the optimal use of equipment and facilities in
the ports. Regarding the complex structure of container ports, this
paper presents a simulation model that compares tow storage
strategies for storing containers in the yard. For this purpose, we
considered loading and unloading norm as an important criterion to
evaluate the performance of Shahid Rajaee container port. By
analysing the results of the model, it will be shown that using
marshalling yard policy instead of current storage system has a
significant effect on the performance level of the port and can
increase the loading and unloading norm up to 14%.
Abstract: Learning programming is difficult for many learners. Some researches have found that the main difficulty relates to cognitive load. Cognitive overload happens in programming due to the nature of the subject which is intrinisicly over-bearing on the working memory. It happens due to the complexity of the subject itself. The problem is made worse by the poor instructional design methodology used in the teaching and learning process. Various efforts have been proposed to reduce the cognitive load, e.g. visualization softwares, part-program method etc. Use of many computer based systems have also been tried to tackle the problem. However, little success has been made to alleviate the problem. More has to be done to overcome this hurdle. This research attempts at understanding how cognitive load can be managed so as to reduce the problem of overloading. We propose a mechanism to measure the cognitive load during pre instruction, post instruction and in instructional stages of learning. This mechanism is used to help the instruction. As the load changes the instruction is made to adapt itself to ensure cognitive viability. This mechanism could be incorporated as a sub domain in the student model of various computer based instructional systems to facilitate the learning of programming.
Abstract: Linear stability analysis of wake-shear layers in twophase
shallow flows is performed in the present paper. Twodimensional
shallow water equations are used in the analysis. It is
assumed that the fluid contains uniformly distributed solid particles.
No dynamic interaction between the carrier fluid and particles is
expected in the initial moment. The stability calculations are
performed for different values of the particle loading parameter and
two other parameters which characterize the velocity ratio and the
velocity deficit. The results show that the particle loading parameter
has a stabilizing effect on the flow while the increase in the velocity
ratio or in the velocity deficit destabilizes the flow.
Abstract: Rolling element bearings are widely used in industry,
especially where high load capacity is required. The diagnosis of
their conditions is essential matter for downtime reduction and saving
cost of maintenance. Therefore, an intensive analysis of frequency
spectrum of their faults must be carried out in order to determine the
main reason of the fault. This paper focus on a beating phenomena
observed in the waveform (time domain) of a cylindrical rolling
element bearing. The beating frequencies were not related to any
sources nearby the machine nor any other malfunctions (unbalance,
misalignment ...etc). More investigation on the spike energy and the
frequency spectrum indicated a problem with races of the bearing.
Multi-harmonics of the fundamental defects frequencies were
observed. Two of them were close to each other in magnitude those
were the source of the beating phenomena.
Abstract: Cylindrical concrete reservoirs are appropriate choice
for storing liquids as water, oil and etc. By using of the pre-cast
concrete reservoirs instead of the in-situ constructed reservoirs, the
speed and precision of the construction would considerably increase.
In this construction method, wall and roof panels would make in
factory with high quality materials and precise controlling. Then,
pre-cast wall and roof panels would carry out to the construction site
for assembling. This method has a few faults such as: the existing
weeks in connection of wall panels together and wall panels to
foundation. Therefore, these have to be resisted under applied loads
such as seismic load. One of the innovative methods which was
successfully applied for seismic retrofitting of numerous pre-cast
cylindrical water reservoirs in New Zealand, using of the high tensile
cables around the reservoirs and post-tensioning them. In this paper,
analytical modeling of wall and roof panels and post-tensioned
cables are carried out with finite element method and the effect of
height to diameter ratio, post-tensioning force value, liquid level in
reservoir, installing position of tendons on seismic response of
reservoirs are investigated.
Abstract: In this paper, the transformers over-load problem of Shiraz substation in Fars Regional Electric Company (FREC) is investigated for a period of three years plan. So the suggestions for using phase shifting transformer (PST) and unified power flow controller (UPFC) in order to solve this problem are examined in details and finally, some economical and practical designs will be given in order to solve the related problems. Practical consideration and using the basic and fundamental concept of powers in transmission lines in order to find the economical design are the main advantages of this research. The simulation results of the integrated overall system with different designs compare them base on economical and practical aspects to solve the over-load and loss-reduction.