Abstract: This paper describes the experimental efficiency of a
compact organic Rankine cycle (ORC) system with a compact
rotary-vane-type expander. The compact ORC system can be used for
power generation from low-temperature heat sources such as waste
heat from various small-scale heat engines, fuel cells, electric devices,
and solar thermal energy. The purpose of this study is to develop an
ORC system with a low power output of less than 1 kW with a hot
temperature source ranging from 60°C to 100°C and a cold
temperature source ranging from 10°C to 30°C. The power output of
the system is rather less due to limited heat efficiency. Therefore, the
system should have an economically optimal efficiency. In order to
realize such a system, an efficient and low-cost expander is
indispensable. An experimental ORC system was developed using the
rotary-vane-type expander which is one of possible candidates of the
expander. The experimental results revealed the expander
performance for various rotation speeds, expander efficiencies, and
thermal efficiencies. Approximately 30 W of expander power output
with 48% expander efficiency and 4% thermal efficiency with a
temperature difference between the hot and cold sources of 80°C was
achieved.
Abstract: One of Effective parameters on the performance of linear induction motors is number of poles which must be selected and optimized to increase power efficiency and motor performance significantly. In this paper a double-sided linear induction motor with different poles number by using MAXWELL3D software is designed and with finite element method is analyzed electromagnetically. Then for dynamic simulation, linear motor by using MATLAB software is simulated. The results show that by adding poles number, system time response is increased and motor after more time reaches to steady state. Also propulsion force of motor is increased.
Abstract: The special and unique advantages of explosive
forming, has developed its use in different industries. Considering the
important influence of improving the current explosive forming
techniques on increasing the efficiency and control over the
explosive forming procedure, the effects of air and water as the
energy-conveying medium, and also their differences will be
illustrated in this paper. Hence, a large number of explosive forming
tests have been conducted on two sizes of thin walled cylindrical
shells by using air and water as the working medium. Comparative
diagrams of the maximum radial deflection of work-pieces of the
same size, as a function of the scaled distance, show that for the
points with the same values of scaled distance, the maximum radial
deformation caused by the under water explosive loading is 4 to 5
times more than the deflection of the shells under explosive forming,
while using air. Results of this experimental research have also been
compared with other studies which show that using water as the
energy conveying media increases the efficiency up to 4.8 times. The
effect of the media on failure modes of the shells, and the necking
mechanism of the walls of the specimens, while being explosively
loaded, are also discussed in this issue. Measuring the tested
specimens shows that, the increase in the internal volume has been
accompanied by necking of the walls, which finally results in the
radial rupture of the structure.
Abstract: This paper proposes an active soft-switching circuit for
bridge converters aiming to improve the power conversion efficiency.
The proposed circuit achieves loss-less switching for both main and
auxiliary switches without increasing the main switch current/voltage
rating. A winding coupled to the primary of power transformer
ensures ZCS for the auxiliary switches during their turn-off. A 350 W,
100 kHz phase shifted full bridge (PSFB) converter is built to validate
the analysis and design. Theoretical loss calculations for proposed
circuit is presented. The proposed circuit is compared with passive
soft switched PSFB in terms of efficiency and loss in duty cycle.
Abstract: The IDR(s) method based on an extended IDR theorem was proposed by Sonneveld and van Gijzen. The original IDR(s) method has excellent property compared with the conventional iterative methods in terms of efficiency and small amount of memory. IDR(s) method, however, has unexpected property that relative residual 2-norm stagnates at the level of less than 10-12. In this paper, an effective strategy for stagnation detection, stagnation avoidance using adaptively information of parameter s and improvement of convergence rate itself of IDR(s) method are proposed in order to gain high accuracy of the approximated solution of IDR(s) method. Through numerical experiments, effectiveness of adaptive tuning IDR(s) method is verified and demonstrated.
Abstract: Frequent patterns are patterns such as sets of features or items that appear in data frequently. Finding such frequent patterns has become an important data mining task because it reveals associations, correlations, and many other interesting relationships hidden in a dataset. Most of the proposed frequent pattern mining algorithms have been implemented with imperative programming languages such as C, Cµ, Java. The imperative paradigm is significantly inefficient when itemset is large and the frequent pattern is long. We suggest a high-level declarative style of programming using a functional language. Our supposition is that the problem of frequent pattern discovery can be efficiently and concisely implemented via a functional paradigm since pattern matching is a fundamental feature supported by most functional languages. Our frequent pattern mining implementation using the Haskell language confirms our hypothesis about conciseness of the program. The performance studies on speed and memory usage support our intuition on efficiency of functional language.
Abstract: As the data-driven economy is growing faster than
ever and the demand for energy is being spurred, we are facing
unprecedented challenges of improving energy efficiency in data
centers. Effectively maximizing energy efficiency or minimising the
cooling energy demand is becoming pervasive for data centers. This
paper investigates overall energy consumption and the energy
efficiency of cooling system for a data center in Finland as a case
study. The power, cooling and energy consumption characteristics
and operation condition of facilities are examined and analysed.
Potential energy and cooling saving opportunities are identified and
further suggestions for improving the performance of cooling system
are put forward. Results are presented as a comprehensive evaluation
of both the energy performance and good practices of energy
efficient cooling operations for the data center. Utilization of an
energy recovery concept for cooling system is proposed. The
conclusion we can draw is that even though the analysed data center
demonstrated relatively high energy efficiency, based on its power
usage effectiveness value, there is still a significant potential for
energy saving from its cooling systems.
Abstract: The deficit of power for electricity demand reaches
almost 30% for consumers in the last few years. This reflects with
continually increasing the price of electricity, and today the price for
small industry is almost 110Euro/MWh. The high price is additional
problem for the owners in the economy crisis which is reflected with
higher price of the goods.
The paper gives analyses of the energy needs for real agro
complex in Macedonia, private vinery with capacity of over 2 million
liters in a year and with self grapes and fruits fields. The existing
power supply is from grid with 10/04 kV transformer. The
geographical and meteorological condition of the vinery location
gives opportunity for including renewable as a power supply option
for the vinery complex.
After observation of the monthly energy needs for the vinery, the
base scenario is the existing power supply from the distribution grid.
The electricity bill in small industry has three factors: electricity in
high and low tariffs in kWh and the power engaged for the
technological process of production in kW. These three factors make
the total electricity bill and it is over 110 Euro/MWh which is the
price near competitive for renewable option. On the other side
investments in renewable (especially photovoltaic (PV)) has tendency
of decreasing with price of near 1,5 Euro/W. This means that
renewable with PV can be real option for power supply for small
industry capacities (under 500kW installed power).
Therefore, the other scenarios give the option with PV and the last
one includes wind option. The paper presents some scenarios for
power supply of the vinery as the followings:
• Base scenario of existing conventional power supply from the
grid
• Scenario with implementation of renewable of Photovoltaic
• Scenario with implementation of renewable of Photovoltaic and
Wind power
The total power installed in a vinery is near 570 kW, but the
maximum needs are around 250kW. At the end of the full paper some
of the results from scenarios will be presented. The paper also
includes the environmental impacts of the renewable scenarios, as
well as financial needs for investments and revenues from renewable.
Abstract: Shrunken patterning for integrated device
manufacturing requires surface cleanliness and surface smoothness in
wet chemical processing [1]. It is necessary to control all process
parameters perfectly especially for the common cleaning technique
RCA clean (SC-1 and SC-2) [2]. In this paper the characteristic and
effect of surface preparation parameters are discussed. The properties
of RCA wet chemical processing in silicon technology is based on
processing time, temperature, concentration and megasonic power of
SC-1 and QDR. An improvement of wafer surface preparation by
the enhanced variables of the wet cleaning chemical process is
proposed.
Abstract: Genetic Algorithms (GAs) are direct searching
methods which require little information from design space. This
characteristic beside robustness of these algorithms makes them to be
very popular in recent decades. On the other hand, while this method
is employed, there is no guarantee to achieve optimum results. This
obliged designer to run such algorithms more than one time to
achieve more reliable results. There are many attempts to modify the
algorithms to make them more efficient. In this paper, by application
of fractal dimension (particularly, Box Counting Method), the
complexity of design space are established for determination of
mutation and crossover probabilities (Pm and Pc). This methodology
is followed by a numerical example for more clarification. It is
concluded that this modification will improve efficiency of GAs and
make them to bring about more reliable results especially for design
space with higher fractal dimensions.
Abstract: This research is to design and implement a new kind
of agitators called differential agitator. The Differential Agitator is an
electro- mechanic set consists of two shafts. The first shaft is the
bearing axis while the second shaft is the axis of the quartet upper
bearing impellers group and the triple lower group which are called
as agitating group. The agitating group is located inside a cylindrical
container equipped especially to contain square directors for the
liquid entrance and square directors called fixing group for the liquid
exit. The fixing group is installed containing the agitating group
inside any tank whether from upper or lower position. The agitating
process occurs through the agitating group bearing causing a lower
pressure over the upper group leading to withdrawing the liquid from
the square directors of the liquid entering and consequently the liquid
moves to the denser place under the quartet upper group. Then, the
liquid moves to the so high pressure area under the agitating group
causing the liquid to exit from the square directors in the bottom of
the container. For improving efficiency, parametric study and shape
optimization has been carried out. A numerical analysis,
manufacturing and laboratory experiments were conducted to design
and implement the differential agitator. Knowing the material
prosperities and the loading conditions, the FEM using ANSYS11
was used to get the optimum design of the geometrical parameters of
the differential agitator elements while the experimental test was
performed to validate the advantages of the differential agitators to
give a high agitation performance of lime in the water as an example.
In addition, the experimental work has been done to express the
internal container shape in the agitation efficiency. The study ended
up with conclusions to maximize agitator performance and optimize
the geometrical parameters to be used for manufacturing the
differential agitator
Abstract: The optical properties of InGaN/GaN laser diode based on quaternary alloys stopper and superlattice layers are numerically studied using ISE TCAD (Integrated System Engineering) simulation program. Improvements in laser optical performance have been achieved using quaternary alloy as superlattice layers in InGaN/GaN laser diodes. Lower threshold current of 18 mA and higher output power and slope efficiency of 22 mW and 1.6 W/A, respectively, at room temperature have been obtained. The laser structure with InAlGaN quaternary alloys as an electron blocking layer was found to provide better laser performance compared with the ternary AlxGa1-xN blocking layer.
Abstract: In this paper we evaluated the efficacy of
photodynamic treatment of infected wounds on pig animal model by
diffuse reflectance spectrometry. The study was conducted on fifteen
wounds contaminated with Staphylococcus aureus bacteria that were
incubated for 30 min with methylene blue solution (c = 3.3 x 10-3 M)
and exposed to laser radiations (λ = 670 nm, P = 15 mW) for 15 min.
The efficiency of photodynamic inactivation of bacteria was
evaluated by microbiological exams and diffuse reflectance
spectrometry. The results of the microbiological exams showed that
the bacterial concentration has decreased from 6.93±0.138
logCFU/ml to 3.12±0.108 logCFU/ml. The spectral examination
showed that the diffuse reflectance of wounds contaminated with
Staphylococcus aureus has decreased from 5.06±0.036 % to
3.36±0.025 %. In conclusion, photodynamic therapy is an effective
method for the treatment of infected wounds and there is a correlation
between the CFU count and diffuse reflectance.
Abstract: Software maintenance, which involves making enhancements, modifications and corrections to existing software systems, consumes more than half of developer time. Specification comprehensibility plays an important role in software maintenance as it permits the understanding of the system properties more easily and quickly. The use of formal notation such as B increases a specification-s precision and consistency. However, the notation is regarded as being difficult to comprehend. Semi-formal notation such as the Unified Modelling Language (UML) is perceived as more accessible but it lacks formality. Perhaps by combining both notations could produce a specification that is not only accurate and consistent but also accessible to users. This paper presents an experiment conducted on a model that integrates the use of both UML and B notations, namely UML-B, versus a B model alone. The objective of the experiment was to evaluate the comprehensibility of a UML-B model compared to a traditional B model. The measurement used in the experiment focused on the efficiency in performing the comprehension tasks. The experiment employed a cross-over design and was conducted on forty-one subjects, including undergraduate and masters students. The results show that the notation used in the UML-B model is more comprehensible than the B model.
Abstract: Online learning with Intelligent Tutoring System (ITS) is becoming very popular where the system models the student-s learning behavior and presents to the student the learning material (content, questions-answers, assignments) accordingly. In today-s distributed computing environment, the tutoring system can take advantage of networking to utilize the model for a student for students from other similar groups. In the present paper we present a methodology where using Case Based Reasoning (CBR), ITS provides student modeling for online learning in a distributed environment with the help of agents. The paper describes the approach, the architecture, and the agent characteristics for such system. This concept can be deployed to develop ITS where the tutor can author and the students can learn locally whereas the ITS can model the students- learning globally in a distributed environment. The advantage of such an approach is that both the learning material (domain knowledge) and student model can be globally distributed thus enhancing the efficiency of ITS with reducing the bandwidth requirement and complexity of the system.
Abstract: This paper provides an exergy analysis of the multistage refrigeration cycle used for C2+ recovery plant. The behavior of an industrial refrigeration cycle with refrigerant propane has been investigated by the exergy method. A computational model based on the exergy analysis is presented for the investigation of the effects of the valves on the exergy losses, the second law of efficiency, and the coefficient of performance (COP) of a vapor compression refrigeration cycle. The equations of exergy destruction and exergetic efficiency for the main cycle components such as evaporators, condensers, compressors, and expansion valves are developed. The relations for the total exergy destruction in the cycle and the cycle exergetic efficiency are obtained. An ethane recovery unit with its refrigeration cycle has been simulated to prepare the exergy analysis. Using a typical actual work input value; the exergetic efficiency of the refrigeration cycle is determined to be 39.90% indicating a great potential for improvements. The simulation results reveal that the exergetic efficiencies of the heat exchanger and expansion sections get the lowest rank among the other compartments of refrigeration cycle. Refrigeration calculations have been carried out through the analysis of T–S and P–H diagrams where coefficient of performance (COP) was obtained as 1.85. The novelty of this article includes the effect and sensitivity analysis of molar flow, pressure drops and temperature on the exergy efficiency and coefficient of performance of the cycle.
Abstract: From environmental aspect purification of ammonia
containing wastewater is expected. High efficiency ammonia
desorption can be done from the water by air on proper temperature.
After the desorption process, ammonia can be recovered and used in
another technology. The calculation method described below give
some methods to find either the minimum column height or ammonia
rich solution of the effluent.
Abstract: The overriding goal of software engineering is to
provide a high quality system, application or a product. To achieve
this goal, software engineers must apply effective methods coupled
with modern tools within the context of a mature software process
[2]. In addition, it is also must to assure that high quality is realized.
Although many quality measures can be collected at the project
levels, the important measures are errors and defects. Deriving a
quality measure for reusable components has proven to be
challenging task now a days. The results obtained from the study are
based on the empirical evidence of reuse practices, as emerged from
the analysis of industrial projects. Both large and small companies,
working in a variety of business domains, and using object-oriented
and procedural development approaches contributed towards this
study. This paper proposes a quality metric that provides benefit at
both project and process level, namely defect removal efficiency
(DRE).
Abstract: This paper investigates the effect of replacing
crankshaft with cam on the indicated torque during compression and
power strokes in internal combustion engines. A Cycloidal cam
profile was used in Revetec engine to calculate and compare the
torque to a conventional engine, using a computational method.
Firstly, the cylinder pressure was calculated using Ferguson equation,
and then the torque calculated depending on cylinder pressure values
in every crank angle. the results showed that by using Cycloidal cam
profile in Revetec engine the torque can increased by 14% compared
with conventional engines, which means an increase in engine
efficiency.
Abstract: This paper is an extension of a previous work where a diagonally implicit harmonic balance method was developed and applied to simulate oscillatory motions of pitching airfoil and wing. A more detailed study on the accuracy, convergence, and the efficiency of the method is carried out in the current paperby varying the number of harmonics in the solution approximation. As the main advantage of the method is itsusage for the design optimization of the unsteady problems, its application to more practical case of rotor flow analysis during forward flight is carried out and compared with flight test data and time-accurate computation results.