Abstract: By analyzing the sources of energy and power
loss in PWM (Pulse Width Modulation) controlled drivers of
water electrolysis cells, it is possible to reduce the power
dissipation and enhance the efficiency of such hydrogen
production units. A PWM controlled power driver is based on
a semiconductor switching element where its power
dissipation might be a remarkable fraction of the total power
demand of an electrolysis system. Power dissipation in a
semiconductor switching element is related to many different
parameters which could be fitted into two main categories:
switching losses and conduction losses. Conduction losses are
directly related to the built, structure and capabilities of a
switching device itself and indeed the conditions in which the
element is handling the switching application such as voltage,
current, temperature and of course the fabrication technology.
On the other hand, switching losses have some other
influencing variables other than the mentioned such as control
system, switching method and power electronics circuitry of
the PWM power driver. By analyzings the characteristics of
recently developed power switching transistors from different
families of Bipolar Junction Transistors (BJT), Metal Oxide
Semiconductor Field Effect Transistors (MOSFET) and
Insulated Gate Bipolar Transistors (IGBT), some
recommendations are made in this paper which are able to
lead to achieve higher hydrogen production efficiency by
utilizing PWM controlled water electrolysis cells.
Abstract: In this paper, perceptions of actors on changes in
crop productivity, quantity and quality of water, and determinants of
their perception are analyzed using descriptive statistics and ordered
logit model. Data collected from 297 Ethiopian farmers and 103
agricultural professionals from December 2009 to January 2010 are
employed. Results show that the majority of the farmers and
professionals recognized decline in water resources, reasoning
climate changes and soil erosion as some of the causes. However,
there is a variation in views on changes in productivity. The
household asset, education level, age and geographical positions are
found to affect farmers- perception on changes in crop productivity.
But, the study underlines that there is no evidence that farmers-
economic status, age, or education level affects recognition of
degradation of water resources. Thus, more focus shall be given on
providing them different coping mechanisms and alternative
resource conserving technologies than educating about the
problems.
Abstract: The current situation in the eurozone raises a number of topics for discussion and to help in finding an answer to the question of whether a common currency is a more suitable means of coping with the impact of the financial crisis or whether national currencies are better suited to this. The economic situation in the EU is now considerably volatile and, due to problems with the fulfilment of the Maastricht convergence criteria, it is now being considered whether, in their further development, new member states will decide to distance themselves from the euro or will, in an attempt to overcome the crisis, speed up the adoption of the euro. The Czech Republic is one country with little interest in adopting the euro, justified by the fact that a better alternative to dealing with this crisis is an independent monetary policy and its ability to respond flexibly to the economic situation not only in Europe, but around the world. One attribute of the crisis in the Czech Republic and its mitigation is the freely floating exchange rate of the national currency. It is not only the Czech Republic that is attempting to alleviate the impact of the crisis, but also new EU member countries facing fresh questions to which theory have yet to provide wholly satisfactory answers. These questions undoubtedly include the problem of inflation targeting and the choice of appropriate instruments for achieving financial stability. The difficulty lies in the fact that these objectives may be contradictory and may require more than one means of achieving them. In this respect we may assume that membership of the euro zone might not in itself mitigate the development of the recession or protect the nation from future crises. We are of the opinion that the decisive factor in the development of any economy will continue to be the domestic economic policy and the operability of market economic mechanisms. We attempt to document this fact using selected countries as examples, these being the Czech Republic, Poland, Hungary, and Slovakia.
Abstract: In intensity modulated radiation therapy (IMRT)
treatment planning, beam angles are usually preselected on the basis of
experience and intuition. Therefore, getting an appropriate beam
configuration needs a very long time. Based on the present situation,
the paper puts forward beam orientation optimization using ant colony
optimization (ACO). We use ant colony optimization to select the
beam configurations, after getting the beam configuration using
Conjugate Gradient (CG) algorithm to optimize the intensity profiles.
Combining with the information of the effect of pencil beam, we can
get the global optimal solution accelerating. In order to verify the
feasibility of the presented method, a simulated and clinical case was
tested, compared with dose-volume histogram and isodose line
between target area and organ at risk. The results showed that the
effect was improved after optimizing beam configurations. The
optimization approach could make treatment planning meet clinical
requirements more efficiently, so it had extensive application
perspective.
Abstract: Multidrug resistant organisms have been taunting the
medical world for the last few decades. Even with new antibiotics
developed, resistant strains have emerged soon after. With the
advancement of nanotechnology, we investigated colloidal silver
nanoparticles for its antimicrobial activity against Pseudomonas
aeruginosa. This organism is a multidrug resistant which contributes
to the high morbidity and mortality in immunocompromised patients.
Five multidrug resistant strains were used in this study. The
antimicrobial effect was studied using the disc diffusion and broth
dilution techniques. An inhibition zone of 11 mm was observed with
10 μg dose of the nanoparticles. The nanoparticles exhibited MIC of
50 μg/ml when added at the lag phase and the subinhibitory
concentration was measured as 100 μg/ml. The MIC50 value showed
to be 15 μg/ml. This study suggests that silver nanoparticles can be
further developed as an antimicrobial agent, hence decreasing the
burden of the multidrug resistance phenomena.
Abstract: The rheological properties of light crude oil and its mixture with water were investigated experimentally. These rheological properties include steady flow behavior, yield stress, transient flow behavior, and viscoelastic behavior. A RheoStress RS600 rheometer was employed in all of the rheological examination tests. The light crude oil exhibits a Newtonian and for emulsion exhibits a non-Newtonian shear thinning behavior over the examined shear rate range of 0.1–120 s-1. In first time, a series of samples of crude oil from the Algerian Sahara has been tested and the results expressed in terms of τ=f(γ) have demonstrated their Newtonian character for the temperature included in [20°C, 70°C]. In second time and at T=20°C, the oil-water emulsions (30%, 50% and 70%) by volume of water), thermodynamically stable, have demonstrated a non-Newtonian rheological behavior that is to say, Herschel-Bulkley and Bingham types. For each type of crude oil-water emulsion, the rheological parameters are calculated by numerical treatment of results.
Abstract: Tribological behavior and wear regimes of ascast
and heattreted Al-Cu-Mg matrix composites containing SiC
particles were studied using a pin-on-disc wear testing apparatus
against an EN32 steel counterface giving emphasis on wear rate as
a function of applied pressures (0.2, 0.6, 1.0 and 1.4 MPa) at
different sliding distances (1000, 2000, 3000, 4000 and 5000
meters) and at a fixed sliding speed of 3.35m/s. The results showed
that the composite exhibited lower wear rate than that of the matrix
alloy and the wear rate of the composites is noted to be invariant to
the sliding distance and is reducing by heat treatment. Wear
regimes such as low, mild and severe wear were observed as per the
Archard-s wear calculations. It is very interesting to note that the
mild wear is almost constant in all the wear regimes.
Abstract: Two-dimensional finite element model was created in this work to investigate the stresses distribution within rock-like samples with offset open non-persistent joints under biaxial loading. The results of this study have explained the fracture mechanisms observed in tests on rock-like material with open non-persistent offset joints [1]. Finite element code SAP2000 was used to study the stresses distribution within the specimens. Four-nodded isoperimetric plain strain element with two degree of freedom per node, and the three-nodded constant strain triangular element with two degree of freedom per node were used in the present study.The results of the present study explained the formation of wing cracks at the tip of the joints for low confining stress as well as the formation of wing cracks at the middle of the joint for the higher confining stress. High shear stresses found in the numerical study at the tip of the joints explained the formation of secondary cracks at the tip of the joints in the experimental study. The study results coincide with the experimental observations which showed that for bridge inclination of 0o, the coalescence occurred due to shear failure and for bridge inclination of 90o the coalescence occurred due to tensile failure while for the other bridge inclinations coalescence occurred due to mixed tensile and shear failure.
Abstract: Sensors possess several properties of physical
measures. Whether devices that convert a sensed signal into an
electrical signal, chemical sensors and biosensors, thus all these
sensors can be considered as an interface between the physical and
electrical equipment. The problem is the analysis of the multitudes of
saved settings as input variables. However, they do not all have the
same level of influence on the outputs. In order to identify the most
sensitive parameters, those that can guide users in gathering
information on the ground and in the process of model calibration
and sensitivity analysis for the effect of each change made.
Mathematical models used for processing become very complex.
In this paper a fuzzy rule-based system is proposed as a solution
for this problem. The system collects the available signals
information from sensors. Moreover, the system allows the study of
the influence of the various factors that take part in the decision
system. Since its inception fuzzy set theory has been regarded as a
formalism suitable to deal with the imprecision intrinsic to many
problems. At the same time, fuzzy sets allow to use symbolic models.
In this study an example was applied for resolving variety of
physiological parameters that define human health state. The
application system was done for medical diagnosis help. The inputs
are the signals expressed the cardiovascular system parameters, blood
pressure, Respiratory system paramsystem was done, it will be able
to predict the state of patient according any input values.
Abstract: The blood ducts must be occluded to avoid loss of
blood from vessels in laparoscopic surgeries. This paper presents a
locking mechanism to be used in a ligation laparoscopic procedure
(LigLAP I), as an alternative solution for a stapling procedure.
Currently, stapling devices are being used to occlude vessels. Using
these devices may result in some problems, including injury of bile
duct, taking up a great deal of space behind the vessel, and bile leak.
In this new procedure, a two-layer suture occludes a vessel. A
locking mechanism is also required to hold the suture. Since there is
a limited space at the device tip, a Shape Memory Alloy (SMA)
actuator is used in this mechanism. Suitability for cleanroom
applications, small size, and silent performance are among the
advantages of SMA actuators in biomedical applications. An
experimental study is conducted to examine the function of the
locking mechanism. To set up the experiment, a prototype of a
locking mechanism is built using nitinol, which is a nickel-titanium
shape memory alloy. The locking mechanism successfully locks a
polymer suture for all runs of the experiment. In addition, the effects
of various surface materials on the applied pulling forces are studied.
Various materials are mounted at the mechanism tip to compare the
maximum pulling forces applied to the suture for each material. The
results show that the various surface materials on the device tip
provide large differences in the applied pulling forces.
Abstract: The effect of varying holding temperature on hatching success, occurrence of deformities and mortality rates were investigated for goldlined seabream eggs. Wild broodstock (600 g) were stocked at a 2:1 male-female ratio in a 2 m3 fiberglass tank supplied with filtered seawater (37 g L-1 salinity, temp. range 24±0.5 oC [day] and 22±1 oC [night], DO2 in excess of 5.0mg L-1). Females were injected with 200 IU kg-1 HCG between 08.00 and 10.00 h and returned to tanks to spawn following which eggs were collected by hand using a 100μm net. Fertilized eggs at the gastrulation stage (120 L-1) were randomly placed into one of 12 experimental 6 L aerated (DO2 5 mg L-1) plastic containers with water temperatures maintained at 24±0.5 oC (ambient), 26±0.5 oC, 28± 0.5 oC and 30±0.5 oC using thermostats. Each treatment was undertaken in triplicate using a 12:12 photophase:scotophase photoperiod. No differences were recorded between eggs reared at 24 and 26 oC with respect to viability, deformity, mortality or unhatched egg rates. Increasing temperature reduced the number of viable eggs with those at 30 oC returning poorest performance (P < 0.05). Mortality levels were lowest for eggs incubated at 24 and 26 oC. The greatest level of deformities recorded was that for eggs reared at 28 oC.
Abstract: International literature emphasizes on the concern regarding the phenomenon of aggression in hospital. This paper focuses on the reality of aggressive interactions reigning within an emergency triage involving three chaps of protagonists: the professionals, the patients and their carers. The data collection was made from a grid of observation, in which the various variables exposed in the literature were integrated. They observations took place around the clock, for three weeks, at the rate of one week a month. In this research 331 aggressive interactions have been listed and analyzed by means of the software SPSS. This research is one of the very few continuous observation surveys in the literature. It shows the various human factors at play in the emergence of aggressive interaction. The data may be used both for taking steps in primary prevention, thanks to the analysis of interaction modes, and in secondary prevention by integrating the useful results in situational prevention.
Abstract: This article presents a detailed analysis and comparative
performance evaluation of model reference adaptive control systems.
In contrast to classical control theory, adaptive control methods allow
to deal with time-variant processes. Inspired by the works [1] and
[2], two methods based on the MIT rule and Lyapunov rule are
applied to a linear first order system. The system is simulated and
it is investigated how changes to the adaptation gain affect the
system performance. Furthermore, variations in the reference model
parameters, that is changing the desired closed-loop behaviour are
examinded.
Abstract: The choice of finite element to use in order to predict
nonlinear static or dynamic response of complex structures becomes
an important factor. Then, the main goal of this research work is to
focus a study on the effect of the in-plane rotational degrees of
freedom in linear and geometrically non linear static and dynamic
analysis of thin shell structures by flat shell finite elements. In this
purpose: First, simple triangular and quadrilateral flat shell finite
elements are implemented in an incremental formulation based on the
updated lagrangian corotational description for geometrically
nonlinear analysis. The triangular element is a combination of DKT
and CST elements, while the quadrilateral is a combination of DKQ
and the bilinear quadrilateral membrane element. In both elements,
the sixth degree of freedom is handled via introducing fictitious
stiffness. Secondly, in the same code, the sixth degrees of freedom in
these elements is handled differently where the in-plane rotational
d.o.f is considered as an effective d.o.f in the in-plane filed
interpolation. Our goal is to compare resulting shell elements. Third,
the analysis is enlarged to dynamic linear analysis by direct
integration using Newmark-s implicit method. Finally, the linear
dynamic analysis is extended to geometrically nonlinear dynamic
analysis where Newmark-s method is used to integrate equations of
motion and the Newton-Raphson method is employed for iterating
within each time step increment until equilibrium is achieved. The
obtained results demonstrate the effectiveness and robustness of the
interpolation of the in-plane rotational d.o.f. and present deficiencies
of using fictitious stiffness in dynamic linear and nonlinear analysis.
Abstract: The great challenge of the agricultural sector is to
produce more crop from less water, which can be achieved by
increasing crop water productivity. The modernization of the
irrigation systems offers a number of possibilities to expand the
economic productivity of water and improve the virtual water status.
The objective of the present study is to assess the global water
productivity (GWP) within the major irrigation command areas of
I.R. Iran. For this purpose, fourteen irrigation command areas where
located in different areas of Iran were selected. In order to calculate
the global water productivity of irrigation command areas, all data on
the delivered water to cropping pattern, cultivated area, crops water
requirement, and yield production rate during 2002-2006 were
gathered. In each of the command areas it seems that the cultivated
crops have a higher amount of virtual water and thus can be replaced
by crops with less virtual water. This is merely suggested due to crop
water consumption and at the time of replacing crops, economic
value as well as cultural and political factors must be considered. The
results indicated that the lowest GWP belongs to Mahyar and
Borkhar irrigation areas, 0.24 kg m-3, and the highest is that of the
Dez irrigation area, 0.81 kg m-3. The findings demonstrated that
water management in the two irrigation areas is just efficient. The
difference in the GWP of irrigation areas is due to variations in the
cropping pattern, amount of crop productions, in addition to the
effective factors in the water use efficiency in the irrigation areas.
Abstract: The incidence of oral cancer in Taiwan increased year
by year. It replaced the nasopharyngeal as the top incurrence among
head and neck cancers since 1994. Early examination and earlier
identification for earlier treatment is the most effective medical
treatment for these cancers. Although the government fully subsidized
the expenses with tremendous promotion program for oral cancer
screening, the citizen-s participation remained low. Purpose of this
study is to understand the factors affecting the citizens- behavior
intensions of taking an oral cancer screening. Based on the Theory of
Planned Behavior, this study adopted four distinctive variables in
explaining the captioned behavior intentions.700 questionnaires were
dispatched with 500 valid responses or 71.4% returned by the citizens
with an age 30 or above from the eastern counties of Taiwan. Test
results has shown that attitude toward, subjective norms of, and
perceived behavioral control over the oral cancer screening varied
from some demographic factors to another. The study proofed that
attitude toward, subjective norms of, and perceived behavioral control
over the oral cancer screening had positive impacts on the
corresponding behavior intention. The test concluded that the theory
of planned behavior was appropriate as a theoretical framework in
explaining the influencing factors of intentions of taking oral cancer
screening. This study suggested the healthcare professional should
provide high accessibility of screening services other than just
delivering knowledge on oral cancer to promote the citizens-
intentions of taking the captioned screening. This research also
provided a practical implication to the healthcare professionals when
formulating and implementing promotion instruments for lifting the
screening rate of oral cancer.
Abstract: Computer networks are essential part in computerbased
information systems. The performance of these networks has a
great influence on the whole information system. Measuring the
usability criteria and customers satisfaction on small computer
network is very important. In this article, an effective approach for
measuring the usability of business network in an information system
is introduced. The usability process for networking provides us with a
flexible and a cost-effective way to assess the usability of a network
and its products. In addition, the proposed approach can be used to
certify network product usability late in the development cycle.
Furthermore, it can be used to help in developing usable interfaces
very early in the cycle and to give a way to measure, track, and
improve usability. Moreover, a new approach for fast information
processing over computer networks is presented. The entire data are
collected together in a long vector and then tested as a one input
pattern. Proposed fast time delay neural networks (FTDNNs) use
cross correlation in the frequency domain between the tested data and
the input weights of neural networks. It is proved mathematically and
practically that the number of computation steps required for the
presented time delay neural networks is less than that needed by
conventional time delay neural networks (CTDNNs). Simulation
results using MATLAB confirm the theoretical computations.
Abstract: Construction cost in India is increasing at around 50
per cent over the average inflation levels. It have registered increase
of up to 15 per cent every year, primarily due to cost of basic
building materials such as steel, cement, bricks, timber and other
inputs as well as cost of labour. As a result, the cost of construction
using conventional building materials and construction is becoming
beyond the affordable limits particularly for low-income groups of
population as well as a large cross section of the middle - income
groups. Therefore, there is a need to adopt cost-effective construction
methods either by up-gradation of traditional technologies using local
resources or applying modern construction materials and techniques
with efficient inputs leading to economic solutions. This has become
the most relevant aspect in the context of the large volume of housing
to be constructed in both rural and urban areas and the consideration
of limitations in the availability of resources such as building
materials and finance. This paper makes an overview of the housing
status in India and adoption of appropriate and cost effective
technologies in the country.
Abstract: Information Retrieval has the objective of studying
models and the realization of systems allowing a user to find the
relevant documents adapted to his need of information. The
information search is a problem which remains difficult because the
difficulty in the representing and to treat the natural languages such
as polysemia. Intentional Structures promise to be a new paradigm to
extend the existing documents structures and to enhance the different
phases of documents process such as creation, editing, search and
retrieval. The intention recognition of the author-s of texts can reduce
the largeness of this problem. In this article, we present intentions
recognition system is based on a semi-automatic method of
extraction the intentional information starting from a corpus of text.
This system is also able to update the ontology of intentions for the
enrichment of the knowledge base containing all possible intentions
of a domain. This approach uses the construction of a semi-formal
ontology which considered as the conceptualization of the intentional
information contained in a text. An experiments on scientific
publications in the field of computer science was considered to
validate this approach.
Abstract: The field of biomedical materials plays an imperative
requisite and a critical role in manufacturing a variety of biological
artificial replacements in a modern world. Recently, titanium (Ti)
materials are being used as biomaterials because of their superior
corrosion resistance and tremendous specific strength, free- allergic
problems and the greatest biocompatibility compared to other
competing biomaterials such as stainless steel, Co-Cr alloys,
ceramics, polymers, and composite materials. However, regardless of
these excellent performance properties, Implantable Ti materials have
poor shear strength and wear resistance which limited their
applications as biomaterials. Even though the wear properties of Ti
alloys has revealed some improvements, the crucial effectiveness of
biomedical Ti alloys as wear components requires a comprehensive
deep understanding of the wear reasons, mechanisms, and techniques
that can be used to improve wear behavior. This review examines
current information on the effect of thermal and thermomechanical
processing of implantable Ti materials on the long-term prosthetic
requirement which related with wear behavior. This paper focuses
mainly on the evolution, evaluation and development of effective
microstructural features that can improve wear properties of bio
grade Ti materials using thermal and thermomechanical treatments.