Abstract: Aluminothermic rail welding was from the beginning
a great success because its low price even in 1895 in Germany. This
method is now, widely used all over the world for the railways
construction, maintenance and modernization. Instructions give you
guidelines for preparing papers for conferences or journals.
After 1989, the welding needs of the potentials beneficiaries
(Romanian Railways, Urban Transportation Companies) keep raise
because of the railways maintenance and modernization necessity.
The main materials that determine the Thermit (T) composition
result from manufacturing scraps all over the country. This can help
the environment by consuming these scraps.
The Romanian need for alumino-thermic welding is now by 11300
per year, and in a favourable economical environment, this amount
can reach 30000 units.
This paper tries to show the effect of two types of modifiers
introduced in the T composition on the structure and properties of an
alumino-thermic welding.
Abstract: The main aim of this paper is to develop and calibrate
an econometric model for modeling prices of long term electricity
futures contracts. The calibration of our model is performed on data
from EEX AG allowing us to capture the specific features of German
electricity market. The data sample contains several structural breaks
which have to be taken into account for modeling. We model the data
with an ARIMAX model which reveals high correlation between the
price of electricity futures contracts and prices of LT futures
contracts of fuels (namely coal, natural gas and crude oil). Besides
this, also a share price index of representative electricity companies
traded on Xetra, spread between 10Y and 1Y German bonds and
exchange rate between EUR and USD appeared to have significant
explanatory power over these futures contracts on EEX.
Abstract: Triglycerides and their derivatives are considered as viable alternatives for diesel fuels. Rice bran oil is used as diesel fuel. Highly viscous rice bran oil can be reduced by blending it with diesel fuel. The present research is aimed to investigate experimentally the performance, exhaust emission and combustion characteristics of a direct injection (DI) diesel engine, typically used in agricultural sector, over the entire load range when fuelled with rice bran oil and diesel fuel blends, RB10 (10% rice bran oil + 90% diesel fuel) to RB50. The performance, emission and combustion parameters of RB20 were found to be very close to neat diesel fuel (ND). The injector opening pressure (IOP) undoubtedly is of prime importance in diesel engine operation. Performance, emission and combustion characteristics with RB30 at enhanced IOPs are better than ND. Improved premixed heat release rate were noticed with RB30 when the IOP is enhanced.
Abstract: In competitive electricity markets all over the world, an adoption of suitable transmission pricing model is a problem as transmission segment still operates as a monopoly. Transmission pricing is an important tool to promote investment for various transmission services in order to provide economic, secure and reliable electricity to bulk and retail customers. The nodal pricing based on SRMC (Short Run Marginal Cost) is found extremely useful by researchers for sending correct economic signals. The marginal prices must be determined as a part of solution to optimization problem i.e. to maximize the social welfare. The need to maximize the social welfare subject to number of system operational constraints is a major challenge from computation and societal point of views. The purpose of this paper is to present a nodal transmission pricing model based on SRMC by developing new mathematical expressions of real and reactive power marginal prices using GA-Fuzzy based optimal power flow framework. The impacts of selecting different social welfare functions on power marginal prices are analyzed and verified with results reported in literature. Network revenues for two different power systems are determined using expressions derived for real and reactive power marginal prices in this paper.
Abstract: Region covariance (RC) descriptor is an effective
and efficient feature for visual tracking. Current RC-based tracking
algorithms use the whole RC matrix to track the target in video
directly. However, there exist some issues for these whole RCbased
algorithms. If some features are contaminated, the whole RC
will become unreliable, which results in lost object-tracking. In
addition, if some features are very discriminative to the
background, other features are still processed and thus reduce the
efficiency. In this paper a new robust tracking method is proposed,
in which the whole RC matrix is decomposed into several low rank
matrices. Those matrices are dynamically chosen and processed so
as to achieve a good tradeoff between discriminability and
complexity. Experimental results have shown that our method is
more robust to complex environment changes, especially either
when occlusion happens or when the background is similar to the
target compared to other RC-based methods.
Abstract: The purpose of this study was to explore the
demographic differences of international tourists according to three
main factors, including the value of time, shopping behavior and
shopping motivation. The Chatuchak Weekend Market is known as
one of the biggest weekend markets in the world. Too little academic
studies had been conducted in this area of weekend market, despite its
growth and continuous development. In general, both domestic
visitors and international tourists are attracted to the perception of
cheap and bargaining prices the weekend market. However, systematic
research study can provide reliable understanding of the perception of
the visitors.
This study focused on the group of international tourists who visited
the market and aimed to provide better insights based on the
differences in their demographic factors. Findings indicated that
several differences in value of time, shopping behavior, and shopping
motivation were identified by gender, income and age. Research
implications and directions for further studies were discussed.
Abstract: With continuous rise of oil price, how to develop alternative energy source has become a hot topic around the world. This study discussed the dynamic characteristics of an island power system operating under random wind speed lower than nominal wind
speeds of wind turbines. The system primarily consists of three diesel engine power generation systems, three constant-speed variable-pitch wind turbines, a small hydraulic induction generation system, and lumped static loads. Detailed models based on Matlab/Simulink were developed to cater for the dynamic behavior of the system. The results suggested this island power system can operate stably in this operational mode. This study can serve as an important reference for planning, operation, and further expansion of island power systems.
Abstract: Rice husk is a lignocellulosic source that can be
converted to ethanol. Three hundreds grams of rice husk was mixed
with 1 L of 0.18 N sulfuric acid solutions then was heated in an
autoclave. The reaction was expected to be at constant temperature
(isothermal), but before that temperature was achieved, reaction has
occurred. The first liquid sample was taken at temperature of 140 0C
and repeated every 5 minute interval. So the data obtained are in the
regions of non-isothermal and isothermal. It was observed that the
degradation has significant effects on the ethanol production. The
kinetic constants can be expressed by Arrhenius equation with the
frequency factors for hydrolysis and sugar degradation of 1.58 x 105
min-1 and 2.29 x 108 L/mole-min, respectively, while the activation
energies are 64,350 J/mole and 76,571 J/mole. The highest ethanol
concentration from fermentation is 1.13% v/v, attained at 220 0C.
Abstract: Nowadays, the focus on renewable energy and alternative fuels has increased due to increasing oil prices, environment pollution, and also concern on preserving the nature. Biodiesel has been known as an attractive alternative fuel although biodiesel produced from edible oil is very expensive than conventional diesel. Therefore, the uses of biodiesel produced from non-edible oils are much better option. Currently Jatropha biodiesel (JBD) is receiving attention as an alternative fuel for diesel engine. Biodiesel is non-toxic, biodegradable, high lubricant ability, highly renewable, and its use therefore produces real reduction in petroleum consumption and carbon dioxide (CO2) emissions. Although biodiesel has many advantages, but it still has several properties need to improve, such as lower calorific value, lower effective engine power, higher emission of nitrogen oxides (NOX) and greater sensitivity to low temperature. Exhaust gas recirculation (EGR) is effective technique to reduce NOX emission from diesel engines because it enables lower flame temperature and oxygen concentration in the combustion chamber. Some studies succeeded to reduce the NOX emission from biodiesel by EGR but they observed increasing soot emission. The aim of this study was to investigate the engine performance and soot emission by using blended Jatropha biodiesel with different EGR rates. A CI engine that is water-cooled, turbocharged, using indirect injection system was used for the investigation. Soot emission, NOX, CO2, carbon monoxide (CO) were recorded and various engine performance parameters were also evaluated.
Abstract: In this paper the gradient based iterative algorithms are presented to solve the following four types linear matrix equations: (a) AXB = F; (b) AXB = F, CXD = G; (c) AXB = F s. t. X = XT ; (d) AXB+CYD = F, where X and Y are unknown matrices, A,B,C,D, F,G are the given constant matrices. It is proved that if the equation considered has a solution, then the unique minimum norm solution can be obtained by choosing a special kind of initial matrices. The numerical results show that the proposed method is reliable and attractive.
Abstract: By using a new set of arithmetic operations on interval numbers, we discuss some arithmetic properties of interval matrices which intern helps us to compute the powers of interval matrices and to solve the system of interval linear equations.
Abstract: Frequent machine breakdowns, low plant availability and increased overtime are a great threat to a manufacturing plant as they increase operating costs of an industry. The main aim of this study was to improve Overall Equipment Effectiveness (OEE) at a manufacturing company through the implementation of innovative maintenance strategies. A case study approach was used. The paper focuses on improving the maintenance in a manufacturing set up using an innovative maintenance regime mix to improve overall equipment effectiveness. Interviews, reviewing documentation and historical records, direct and participatory observation were used as data collection methods during the research. Usually production is based on the total kilowatt of motors produced per day. The target kilowatt at 91% availability is 75 Kilowatts a day. Reduced demand and lack of raw materials particularly imported items are adversely affecting the manufacturing operations. The company had to reset its targets from the usual figure of 250 Kilowatt per day to mere 75 per day due to lower availability of machines as result of breakdowns as well as lack of raw materials. The price reductions and uncertainties as well as general machine breakdowns further lowered production. Some recommendations were given. For instance, employee empowerment in the company will enhance responsibility and authority to improve and totally eliminate the six big losses. If the maintenance department is to realise its proper function in a progressive, innovative industrial society, then its personnel must be continuously trained to meet current needs as well as future requirements. To make the maintenance planning system effective, it is essential to keep track of all the corrective maintenance jobs and preventive maintenance inspections. For large processing plants these cannot be handled manually. It was therefore recommended that the company implement (Computerised Maintenance Management System) CMMS.
Abstract: In this paper, the least-squares design of variable fractional-delay (VFD) finite impulse response (FIR) digital differentiators is proposed. The used transfer function is formulated so that Farrow structure can be applied to realize the designed system. Also, the symmetric characteristics of filter coefficients are derived, which leads to the complexity reduction by saving almost a half of the number of coefficients. Moreover, all the elements of related vectors or matrices for the optimal process can be represented in closed forms, which make the design easier. Design example is also presented to illustrate the effectiveness of the proposed method.
Abstract: In this paper a controller for the pitch angle of an
aircraft regarding to the elevator deflection angle is designed.
The way how the elevator angle affects pitching motion of the
aircraft is pointed out, as well as, how a pitch controller can be
applied for the aircraft to reach certain pitch angle. In this digital
optimal system, the elevator deflection angle and pitching angle
of the plane are considered to be input and output respectively.
A single input single output (SISO) system is presented. A
digital pitch aircraft control is demonstrated. A simulation for
the whole system has been performed. The optimal control
weighting vectors, Q and R have been determined.
Abstract: In a liberalized electricity market, it is not surprising
that different customers require different power quality (PQ) levels at
different price. Power quality related to several power disturbances is
described by many parameters, so how to define a comprehensive
hierarchy evaluation system of power quality (PQCHES) has become
a concerned issue. In this paper, based on four electromagnetic
compatibility (EMC) levels, the numerical range of each power
disturbance is divided into five grades (Grade I –Grade V), and the
“barrel principle" of power quality is used for the assessment of
overall PQ performance with only one grade indicator. A case study
based on actual monitored data of PQ shows that the site PQ grade
indicates the electromagnetic environment level and also expresses the
characteristics of loads served by the site.
The shortest plank principle of PQ barrel is an incentive
mechanism, which can combine with the rewards/penalty mechanism
(RPM) of consumed energy “on quality demand", to stimulate utilities
to improve the overall PQ level and also stimulate end-user more
“smart" under the infrastructure of future SmartGrid..
Abstract: Self-compacting concrete (SCC), a new kind of high
performance concrete (HPC) have been first developed in Japan in
1986. The development of SCC has made casting of dense
reinforcement and mass concrete convenient, has minimized noise.
Fresh self-compacting concrete (SCC) flows into formwork and
around obstructions under its own weight to fill it completely and
self-compact (without any need for vibration), without any
segregation and blocking. The elimination of the need for
compaction leads to better quality concrete and substantial
improvement of working conditions. SCC mixes generally have a
much higher content of fine fillers, including cement, and produce
excessively high compressive strength concrete, which restricts its
field of application to special concrete only. To use SCC mixes in
general concrete construction practice, requires low cost materials to
make inexpensive concrete.
Rice husk ash (RHA) has been used as a highly reactive
pozzolanic material to improve the microstructure of the interfacial
transition zone (ITZ) between the cement paste and the aggregate in
self compacting concrete. Mechanical experiments of RHA blended
Portland cement concretes revealed that in addition to the pozzolanic
reactivity of RHA (chemical aspect), the particle grading (physical
aspect) of cement and RHA mixtures also exerted significant
influences on the blending efficiency.
The scope of this research was to determine the usefulness of Rice
husk ash (RHA) in the development of economical self compacting
concrete (SCC). The cost of materials will be decreased by reducing
the cement content by using waste material like rice husk ash instead
of.
This paper presents a study on the development of Mechanical
properties up to 180 days of self compacting and ordinary concretes
with rice-husk ash (RHA), from a rice paddy milling industry in
Rasht (Iran). Two different replacement percentages of cement by
RHA, 10%, and 20%, and two different water/cementicious material
ratios (0.40 and 0.35), were used for both of self compacting and
normal concrete specimens. The results are compared with those of
the self compacting concrete without RHA, with compressive,
flexural strength and modulus of elasticity. It is concluded that RHA
provides a positive effect on the Mechanical properties at age after
60 days.
Base of the result self compacting concrete specimens have higher
value than normal concrete specimens in all test except modulus of
elasticity. Also specimens with 20% replacement of cement by RHA
have the best performance.
Abstract: This study employs a bivariate asymmetric GARCH
model to reveal the hidden dynamics price changes and volatility
among the emerging markets of Thailand and Malaysian after the
Asian financial crisis from January 2001 to December 2008. Our
results indicated that the equity markets are sharing the common
information (shock) that transmitted among each others. These
empirical findings are used to demonstrate the importance of shock
and volatility dynamic transmissions in the cross-market hedging and
market risk.
Abstract: The goal of this paper is to develop a model to
integrate “pricing" and “advertisement" for short life cycle products,
such as branded fashion clothing products. To achieve this goal, we
apply the concept of “Dynamic Pricing". There are two classes of
advertisements, for the brand (regardless of product) and for a
particular product. Advertising the brand affects the demand and
price of all the products. Thus, the model considers all these products
in relation with each other. We develop two different methods to
integrate both types of advertisement and pricing. The first model is
developed within the framework of dynamic programming. However,
due to the complexity of the model, this method cannot be applicable
for large size problems. Therefore, we develop another method,
called hieratical approach, which is capable of handling the real
world problems. Finally, we show the accuracy of this method, both
theoretically and also by simulation.
Abstract: This paper discusses the performance modeling and availability analysis of Yarn Dyeing System of a Textile Industry. The Textile Industry is a complex and repairable engineering system. Yarn Dyeing System of Textile Industry consists of five subsystems arranged in series configuration. For performance modeling and analysis of availability, a performance evaluating model has been developed with the help of mathematical formulation based on Markov-Birth-Death Process. The differential equations have been developed on the basis of Probabilistic Approach using a Transition Diagram. These equations have further been solved using normalizing condition in order to develop the steady state availability, a performance measure of the system concerned. The system performance has been further analyzed with the help of decision matrices. These matrices provide various availability levels for different combinations of failure and repair rates for various subsystems. The findings of this paper are therefore, considered to be useful for the analysis of availability and determination of the best possible maintenance strategies which can be implemented in future to enhance the system performance.
Abstract: Lack of resources for road infrastructure financing is a
problem that currently affects not only eastern European economies
but also many other countries especially in relation to the impact of
global financial crisis. In this context, we are talking about the socalled
short-investment problem as a result of long-term lack of
investment resources. Based on an analysis of road infrastructure
financing in the Czech Republic this article points out at weaknesses
of current system and proposes a long-term planning methodology
supported by system approach. Within this methodology and using
created system dynamic model the article predicts the development of
short-investment problem in the Country and in reaction on the
downward trend of certain sources the article presents various
scenarios resulting from the change of the structure of financial
sources. In the discussion the article focuses more closely on the
possibility of introduction of tax on vehicles instead of taxes with
declining revenue streams and estimates its approximate price in
relation to reaching various solutions of short-investment in time.