Abstract: In this study, the performance of a high-frequency arc
welding machine including a two-switch inverter is analyzed. The
control of the system is achieved using two different control
techniques i- fuzzy logic control (FLC) ii- state space averaging
based sliding control. Fuzzy logic control does not need accurate
mathematical model of a plant and can be used in nonlinear
applications. The second method needs the mathematical model of
the system. In this method the state space equations of the system are
derived for two different “on" and “off" states of the switches. The
derived state equations are combined with the sliding control rule
considering the duty-cycle of the converter. The performance of the
system is analyzed by simulating the system using SIMULINK tool
box of MATLAB. The simulation results show that fuzzy logic
controller is more robust and less sensitive to parameter variations.
Abstract: Celiac disease is an immune-mediated disease, triggered in genetically susceptible individuals by ingested gluten from wheat, rye, barley and other closely related cereal grains. The only effective treatment is a strict gluten free diet for life. Latvian producers do not offer gluten-free products. In this research, use of extruded maize flour was tested for substituting rice, maize or buckwheat flour in gluten-free bread formulations at different ratios. Also the influence of extruded maize flour on the quality parameters of gluten-free bread was investigated. The aim of research was to study the influence of extruded maize flour on gluten-free bread quality. Addition of extruded maize flour affect gluten-free bread crumb color, structure of crumb, weight loss and dry off of bread.
Abstract: Recent fifteen years witnessed fast improvements in the field of humanoid robotics. The human-like robot structure is
more suitable to human environment with its supreme obstacle avoidance properties when compared with wheeled service robots.
However, the walking control for bipedal robots is a challenging task
due to their complex dynamics. Stable reference generation plays a very important role in control.
Linear Inverted Pendulum Model (LIPM) and the Zero Moment Point (ZMP) criterion are applied in a number of studies for stable
walking reference generation of biped walking robots. This paper follows this main approach too. We propose a natural and continuous ZMP reference trajectory for a stable and human-like walk. The ZMP reference trajectories move forward under the sole of the support foot when the robot body is supported by a single leg. Robot center of mass trajectory is obtained
from predefined ZMP reference trajectories by a Fourier series
approximation method. The Gibbs phenomenon problem common with Fourier approximations of discontinuous functions is avoided by employing continuous ZMP references. Also, these ZMP reference
trajectories possess pre-assigned single and double support phases,
which are very useful in experimental tuning work.
The ZMP based reference generation strategy is tested via threedimensional
full-dynamics simulations of a 12-degrees-of-freedom
biped robot model. Simulation results indicate that the proposed reference trajectory generation technique is successful.
Abstract: The purpose of this paper is to present the design and
instrumentation of a new benchmark multivariable nonlinear control
laboratory. The mathematical model of this system may be used to
test the applicability and performance of various nonlinear control
procedures. The system is a two degree-of-freedom robotic arm with
soft and hard (discontinuous) nonlinear terms. Two novel
mechanisms are designed to allow the implementation of adjustable
Coulomb friction and backlash.
Abstract: Using ab initio theoretical calculations, we present
analysis of fragmentation process. The analysis is performed in two
steps. The first step is calculation of fragmentation energies by ab
initio calculations. The second step is application of the energies to
kinetic description of process. The energies of fragments are
presented in this paper. The kinetics of fragmentation process can be
described by numerical models. The method for kinetic analysis is
described in this paper. The result - composition of fragmentation
products - will be calculated in future. The results from model can be
compared to the concentrations of fragments from mass spectrum.
Abstract: This work proposes a set of actions to assist redesign
procedure in existing products of Electric and Electronic Equipment
(EEE). The aim is to improve their environmental behavior after their
withdrawal in the End-of-Life (EOL) phase. In the beginning data
collection takes place. Then follows selection and implementation of
the optimal EOL Treatment Strategy (EOL_TS) and its results-
evaluation concerning the environment. In parallel, product design
characteristics that can be altered are selected based on their
significance for the environment in the EOL stage. All results from
the previous stages are combined and possible redesign actions are
formulated for further examination and afterwards configuration in
the design stage. The applied method to perform these tasks is Lean
Thinking (LT). At the end, results concerning the application of the
proposed method on a distribution transformer are presented.
Abstract: Although the Vietnamese catfish farming has grown
at very high rates in recent years, the industry has also faced many
problems affecting its sustainability. This paper studies the
perceptions of catfish farmers regarding risk and risk management
strategies in their production activities. Specifically, the study aims
to measure the consequences, likelihoods, and levels of risks as well
as the efficacy of risk management in Vietnamese catfish farming.
Data for the study were collected through a sample of 261 catfish
farmers in the Mekong Delta, Vietnam using a questionnaire survey
in 2008. Results show that, in general, price and production risks
were perceived as the most important risks. Farm management and
technical measures were perceived more effective than other kinds of
risk management strategies in risk reduction. Although price risks
were rated as important risks, price risk management strategies were
not perceived as important measures for risk mitigation. The results
of the study are discussed to provide implications for various
industry stakeholders, including policy makers, processors, advisors,
and developers of new risk management strategies.
Abstract: In today-s competitive market, most companies
develop manufacturing systems that can help in cost reduction and
maximum quality. Human issues are an important part of
manufacturing systems, yet most companies ignore their effects on
production performance. This paper aims to developing an integrated
workforce planning system that incorporates the human being.
Therefore, a multi-objective mixed integer nonlinear programming
model is developed to determine the amount of hiring, firing,
training, overtime for each worker type. This paper considers a
workforce planning model including human aspects such as skills,
training, workers- personalities, capacity, motivation, and learning
rates. This model helps to minimize the hiring, firing, training and
overtime costs, and maximize the workers- performance. The results
indicate that the workers- differences should be considered in
workforce scheduling to generate realistic plans with minimum costs.
This paper also investigates the effects of human learning rates on the
performance of the production systems.
Abstract: The periodic mixed convection of a water-copper
nanofluid inside a rectangular cavity with aspect ratio of 3 is
investigated numerically. The temperature of the bottom wall of the
cavity is assumed greater than the temperature of the top lid which
oscillates horizontally with the velocity defined as u = u0 sin (ω t).
The effects of Richardson number, Ri, and volume fraction of
nanoparticles on the flow and thermal behavior of the nanofluid are
investigated. Velocity and temperature profiles, streamlines and
isotherms are presented. It is observed that when Ri < 1, heat transfer
rate is much greater than when Ri > 1. The higher value of Ri
corresponds to a lower value of the amplitude of the oscillation of
Num in the steady periodic state. Moreover, increasing the volume
fraction of the nanoparticles increases the heat transfer rate.
Abstract: Soft set theory was initiated by Molodtsov in 1999. In the past years, this theory had been applied to many branches of mathematics, information science and computer science. In 2003, Maji et al. introduced some operations of soft sets and gave some operational rules. Recently, some of these operational rules are pointed out to be not true. Furthermore, Ali et al., in their paper, introduced and discussed some new operations of soft sets. In this paper, we further investigate these operational rules given by Maji et al. and Ali et al.. We obtain some sufficient-necessary conditions such that corresponding operational rules hold and give correct forms for some operational rules. These results will be help for us to use rightly operational rules of soft sets in research and application of soft set theory.
Abstract: The present paper is a case study about exploitation of
Kheir Abad river (Khoozestan, Iran) water resources and the
problems caused by river sediments around the pumping stations.
The weak points and strong points of Boneh Basht pumping station
have been studied by experienced experts, work teams, and
consulting engineers and technical and executive solutions have been
suggested. Therefore, the suggestions of this article are based on the
performed studies and are proposed in order to evaluate the logical
solutions.
Rather complicated processes resulting from the interaction of
water flows and sediments observed at Boneh Basht pumping station
occur at other pumping stations in almost the same way. Therefore,
Boneh Basht pumping station can be selected as a sample (pilot) and
up-to-date theories and experiences can be applied to this station and
the results can be offered to other stations.
Abstract: Learning using labeled and unlabelled data has
received considerable amount of attention in the machine learning
community due its potential in reducing the need for expensive
labeled data. In this work we present a new method for combining
labeled and unlabeled data based on classifier ensembles. The model
we propose assumes each classifier in the ensemble observes the
input using different set of features. Classifiers are initially trained
using some labeled samples. The trained classifiers learn further
through labeling the unknown patterns using a teaching signals that is
generated using the decision of the classifier ensemble, i.e. the
classifiers self-supervise each other. Experiments on a set of object
images are presented. Our experiments investigate different classifier
models, different fusing techniques, different training sizes and
different input features. Experimental results reveal that the proposed
self-supervised ensemble learning approach reduces classification
error over the single classifier and the traditional ensemble classifier
approachs.
Abstract: Despite the fact that Knowledge Sharing (KS) is very important, we found only little discussion about the reasons why people have the willingness to share knowledge at such platform even though there is no immediate benefit to the persons who contribute knowledge in it. The aim of this study is to develop an integrative understanding of the factors that support or inhibit individuals- knowledge sharing intentions in virtual communities and to find whether habit would generate people-s willingness to be involved. We apply Social Capital Theory (SCT), and we also add two dimensions for discussion: member incentive and habitual domain (HD). This research assembles the questionnaire from individuals who have experienced knowledge sharing in virtual communities, and applies survey and Structural Equation Model (SEM) to analyze the results from the questionnaires. Finally, results confirm that individuals are willing to share knowledge in virtual communities: (1) if they consider reciprocity, centrality, and have longer tenure in their field, and enjoy helping. (2) if they have the habit of sharing knowledge. This study is useful for the developers of virtual communities to insight into knowledge sharing in cyberspace.
Abstract: Nowadays the devices of night vision are widely used both for military and civil applications. The variety of night vision applications require a variety of the night vision devices designs. A web-based architecture of a software system for design assessment before producing of night vision devices is developed. The proposed architecture of the web-based system is based on the application of a mathematical model for designing of night vision devices. An algorithm with two components – for iterative design and for intelligent design is developed and integrated into system architecture. The iterative component suggests compatible modules combinations to choose from. The intelligent component provides compatible combinations of modules satisfying given user requirements to device parameters. The proposed web-based architecture of a system for design assessment of night vision devices is tested via a prototype of the system. The testing showed the applicability of both iterative and intelligent components of algorithm.
Abstract: This paper analysis performance of disbursement
procedure of public works project in Thailand. The results of
research were summarised based on contracts, submitted invoice,
inspection dated, copies of disbursement dated between client and
their main contractor and interviewed with persons involved in
central and local government projects during 1994-2008 in Thailand.
The data collection was to investigate the disbursement procedure
related to performance in disbursement during construction period
(Planned duration of contract against Actual execution date in each
month). A graphical presentation of a duration analysis of the
projects illustrated significant disbursement formation in each
project. It was established that the shortage of staff, the financial
stability of clients, bureaucratic, method of disbursement and
economics situation has play major role on performance of
disbursement to their main contractors.
Abstract: Operating a device at high power and high frequency
is a major problem because wall losses greatly reduce the efficiency
of the device. In the present communication, authors analytically
analyzed the dependence of ohmic/RF efficiency, the fraction of
output power with respect to the total power generated, of gyrotron
cavity structure on the conductivity of copper for the second
harmonic TE0,6 mode. This study shows a rapid fall in the RF
efficiency as the quality (conductivity) of copper degrades. Starting
with an RF efficiency near 40% at the conductivity of ideal copper
(5.8 x 107 S/m), the RF efficiency decreases (upto 8%) as the copper
quality degrades. Assuming conductivity half that of ideal copper the
RF efficiency as a function of diffractive quality factor, Qdiff, has
been studied. Here the RF efficiency decreases rapidly with
increasing diffractive Q. Ohmic wall losses as a function of
frequency for 460 GHz gyrotron cavity excited in TE0,6 mode has
also been analyzed. For 460 GHz cavity, the extracted power is
reduced to 32% of the generated power due to ohmic losses in the
walls of the cavity.
Abstract: The many feasible alternatives and conflicting
objectives make equipment selection in materials handling a
complicated task. This paper presents utilizing Monte Carlo (MC)
simulation combined with the Analytic Hierarchy Process (AHP) to
evaluate and select the most appropriate Material Handling
Equipment (MHE). The proposed hybrid model was built on the base
of material handling equation to identify main and sub criteria critical
to MHE selection. The criteria illustrate the properties of the material
to be moved, characteristics of the move, and the means by which the
materials will be moved. The use of MC simulation beside the AHP
is very powerful where it allows the decision maker to represent
his/her possible preference judgments as random variables. This will
reduce the uncertainty of single point judgment at conventional AHP,
and provide more confidence in the decision problem results. A small
business pharmaceutical company is used as an example to illustrate
the development and application of the proposed model.
Abstract: The most important property of the Gene Ontology is
the terms. These control vocabularies are defined to provide
consistent descriptions of gene products that are shareable and
computationally accessible by humans, software agent, or other
machine-readable meta-data. Each term is associated with
information such as definition, synonyms, database references, amino
acid sequences, and relationships to other terms. This information has
made the Gene Ontology broadly applied in microarray and
proteomic analysis. However, the process of searching the terms is
still carried out using traditional approach which is based on keyword
matching. The weaknesses of this approach are: ignoring semantic
relationships between terms, and highly depending on a specialist to
find similar terms. Therefore, this study combines semantic similarity
measure and genetic algorithm to perform a better retrieval process
for searching semantically similar terms. The semantic similarity
measure is used to compute similitude strength between two terms.
Then, the genetic algorithm is employed to perform batch retrievals
and to handle the situation of the large search space of the Gene
Ontology graph. The computational results are presented to show the
effectiveness of the proposed algorithm.
Abstract: Electronic banking must be secure and easy to use and
many banks heavily advertise an apparent of 100% secure system
which is contestable in many points. In this work, an alternative
approach to the design of e-banking system, through a new solution
for user authentication and security with digital certificate called
LumaCert is introduced. The certificate applies new algorithm for
asymmetric encryption by utilizing two mathematical operators
called Pentors and UltraPentors. The public and private key in this
algorithm represent a quadruple of parameters which are directly
dependent from the above mentioned operators. The strength of the
algorithm resides in the inability to find the respective Pentor and
UltraPentor operator from the mentioned parameters.
Abstract: In this paper, a new automated methodology to detect the optic disc (OD) automatically in retinal images from patients with risk of being affected by Diabetic Retinopathy (DR) and Macular Edema (ME) is presented. The detection procedure comprises two independent methodologies. On one hand, a location methodology obtains a pixel that belongs to the OD using image contrast analysis and structure filtering techniques and, on the other hand, a boundary segmentation methodology estimates a circular approximation of the OD boundary by applying mathematical morphology, edge detection techniques and the Circular Hough Transform. The methodologies were tested on a set of 1200 images composed of 229 retinographies from patients affected by DR with risk of ME, 431 with DR and no risk of ME and 540 images of healthy retinas. The location methodology obtained 98.83% success rate, whereas the OD boundary segmentation methodology obtained good circular OD boundary approximation in 94.58% of cases. The average computational time measured over the total set was 1.67 seconds for OD location and 5.78 seconds for OD boundary segmentation.