Abstract: Natural gas, as one of the most important sources of
energy for many of the industrial and domestic users all over the
world, has a complex, huge supply chain which is in need of heavy
investments in all the phases of exploration, extraction, production,
transportation, storage and distribution. The main purpose of supply
chain is to meet customers’ need efficiently and with minimum cost.
In this study, with the aim of minimizing economic costs, different
levels of natural gas supply chain in the form of a multi-echelon,
multi-period fuzzy linear programming have been modeled. In this
model, different constraints including constraints on demand
satisfaction, capacity, input/output balance and presence/absence of a
path have been defined. The obtained results suggest efficiency of the
recommended model in optimal allocation and reduction of supply
chain costs.
Abstract: The objectives of this study is to investigate the
existence of the sticky cost behavior of firms listed in the Indonesia
Stock Exchange (IDX) and to find evidence on the effects of sticky
operating expenses (SG&A expenses) on profitability of firms. For
the first objective, this study finds that the sticky cost behavior does
exist. For the second objective, this study finds that the stickier the
operating expenses the lesser future profitability of the firms. This
study concludes that sticky cost affects negatively to the performance
and, therefore, firms should include flexibility in designing the cost
structure of their firms.
Abstract: Online forum is part of a Learning Management
System (LMS) environment in which students share their opinions.
This study attempts to investigate the perceptions of students towards
online forum and their patterns of listening behavior during the forum
interaction. The students’ perceptions were measured using a
questionnaire, in which seven dimensions were used involving online
experience, benefits of forum participation, cost of participation,
perceived ease of use, usefulness, attitude, and intention. Meanwhile,
their patterns of listening behaviors were obtained using the log file
extracted from the LMS. A total of 25 postgraduate students
undertaking a course were involved in this study, and their activities
in the forum session were recorded by the LMS and used as a log file.
The results from the questionnaire analysis indicated that the students
perceived that the forum is easy to use, useful, and bring benefits to
them. Also, they showed positive attitude towards online forum, and
they have the intention to use it in future. Based on the log data, the
participants were also divided into six clusters of listening behavior,
in which they are different in terms of temporality, breadth, depth and
speaking level. The findings were compared to previous clusters
grouping and future recommendations are also discussed.
Abstract: This paper presents a method for the efficient
implementation of a unidirectional or bidirectional DC/DC converter.
The DC/DC converter is used essentially for energy exchange
between the low voltage service battery and a high voltage battery
commonly found in Electric Vehicle applications. In these
applications, apart from cost, efficiency of design is an important
characteristic. A useful way to reduce the size of electronic
equipment in the electric vehicles is proposed in this paper. The
technique simplifies the mechanical complexity and maximizes the
energy usage using the latest converter control techniques. Moreover
a bidirectional battery charger for hybrid electric vehicles is also
implemented in this paper. Several simulations on the test system
have been carried out in Matlab/Simulink environment. The results
exemplify the robustness of the proposed design methodology in case
of a 1.5 KW DC-DC converter.
Abstract: Ancillary services are support services which are
essential for humanizing and enhancing the reliability and security of
the electric power system. Reactive power ancillary service is one of
the important ancillary services in a restructured electricity market
which determines the cost of supplying ancillary services and finding
of how this cost would change with respect to operating decisions.
This paper presents a new formation that can be used to minimize the
Independent System Operator (ISO)’s total payment for reactive
power ancillary service. The modified power flow tracing algorithm
estimates the availability of reserve reactive power for ancillary
service. In order to find optimum reactive power dispatch,
Biogeography based optimization method (BPO) is proposed. Market
Reactive Clearing Price (MRCP) is then estimated and it encourages
generator companies (GENCOs) to participate in an ancillary service.
Finally, optimal weighting factor and real time utilization factor of
reactive power give the minimum ISO’s total payment. The
effectiveness of proposed design is verified using IEEE 30 bus
system.
Abstract: In this paper the effect of wall waviness of side walls
in a two-dimensional wavy enclosure is numerically investigated.
Two vertical wavy walls and straight top wall are kept isothermal and
the bottom wall temperature is higher and spatially varying with
cosinusoidal temperature distribution. A computational code based on
Finite-volume approach is used to solve governing equations and
SIMPLE method is used for pressure velocity coupling. Test is
performed for several different numbers of undulations. The Prandtl
number was kept constant and the Ra number denotes that the flow is
laminar. Temperature and velocity fields are determined. Therefore,
according to the obtained results a correlation is proposed for average
Nusselt number as a function of number of side wall waves. The
results indicate that the Nusselt number is highly affected by number
of waves and increasing it decreases the wavy walls Nusselt number;
although the Nusselt number is not highly affected by surface
waviness when the number of undulations is below one.
Abstract: Innovations not only contribute to competitiveness of
the company but have also positive effects on revenues. On average,
product innovations account to 14 percent of companies’ sales.
Innovation management has substantially changed during the last
decade, because of growing reliance on external partners. As a
consequence, a new task for purchasing arises, as firms need to
understand which suppliers actually do have high potential
contributing to the innovativeness of the firm and which do not.
Proper organization of the purchasing function is important since
for the majority of manufacturing companies deal with substantial
material costs which pass through the purchasing function. In the past
the purchasing function was largely seen as a transaction-oriented,
clerical function but today purchasing is the intermediate with supply
chain partners contributing to innovations, be it product or process
innovations. Therefore, purchasing function has to be organized
differently to enable firm innovation potential.
However, innovations are inherently risky. There are behavioral
risk (that some partner will take advantage of the other party),
technological risk in terms of complexity of products and processes
of manufacturing and incoming materials and finally market risks,
which in fact judge the value of the innovation. These risks are
investigated in this work. Specifically, technological risks which deal
with complexity of the products, and processes will be investigated
more thoroughly. Buying components or such high edge technologies
necessities careful investigation of technical features and therefore is
usually conducted by a team of experts. Therefore it is hypothesized
that higher the technological risk, higher will be the centralization of
the purchasing function as an interface with other supply chain
members.
Main contribution of this research lies is in the fact that analysis
was performed on a large data set of 1493 companies, from 25
countries collected in the GMRG 4 survey. Most analyses of
purchasing function are done by case study analysis of innovative
firms. Therefore this study contributes with empirical evaluations that
can be generalized.
Abstract: The goal of this article is the analysis of knowledge
transfer at the regional level of the Czech Republic. We show how
goals of enterprises´ innovative activities are related to the rate of
cooperation with different actors within regional innovative systems
as well as in other world regions. The results show that the most
important partners of enterprises are their suppliers and clients in
most Czech regions. The cooperation rate of enterprises correlates
significantly mainly with enterprises´ efforts to enter new markets
and reduce labour costs per unit output. The meaning of this
cooperation decreases with the increase of partner’s distance.
Regarding the type of a cooperating partner, cooperation within an
enterprise had to do with the increase of market share and decrease of
labour costs. On the other hand, cooperation with clients had to do
with efforts to replace outdated products or processes or enter new
markets. We can pay less attention to the cooperation with
government authorities and organizations. The reasons for
marginalization of this cooperation should be submitted to further
detailed investigation.
Abstract: The systematic evaluation of manufacturing
technologies with regard to the potential for product designing
constitutes a major challenge. Until now, conventional evaluation
methods primarily consider the costs of manufacturing technologies.
Thus, the potential of manufacturing technologies for achieving
additional product design features is not completely captured. To
compensate this deficit, final evaluations of new technologies are
mainly intuitive in practice. Therefore, an additional evaluation
dimension is needed which takes the potential of manufacturing
technologies for specific realizable product designs into account. In
this paper, we present the approach of an evaluation method for
selecting manufacturing technologies with regard to their potential
for product designing. This research is done within the Fraunhofer
innovation cluster »AdaM« (Adaptive Manufacturing) which targets
the development of resource efficient and adaptive manufacturing
technology processes for complex turbomachinery components.
Abstract: This research focuses on the optimization of glazed
surfaces and the assessment of possible solar gains in industrial
buildings. Existing window rating methods for single windows were
evaluated and a new method for a simple analysis of energy gains and
losses by single windows was introduced. Furthermore extensive
transient building simulations were carried out to appraise the
performance of low cost polycarbonate multi-cell sheets in
interaction with typical buildings for industrial applications. Mainly
energy saving potential was determined by optimizing the orientation
and area of such glazing systems in dependency on their thermal
qualities. Moreover the impact on critical aspects such as summer
overheating and daylight illumination was considered to ensure the
user comfort and avoid additional energy demand for lighting or
cooling. Hereby the simulated heating demand could be reduced by
up to 1/3 compared to traditional architecture of industrial halls using
mainly skylights.
Abstract: The majority of contemporary insulation materials
commonly used in the building industry is made from non-renewable
raw materials; furthermore, their production often brings high energy
costs. A long-term trend as far as sustainable development is
concerned has been the reduction of energy and material demands of
building material production. One of the solutions is the possibility of
using easily renewable natural raw material sources which are
considerably more ecological and their production is mostly less
energy-consuming compared to the production of normal insulations
(mineral wool, polystyrene). The paper describes the results of
research focused on the development of thermal and acoustic
insulation materials based on natural fibres intended for floor
constructions. Given the characteristic open porosity of natural fibre
materials, the hygrothermal behaviour of the developed materials was
studied. Especially the influence of relative humidity and temperature
on thermal insulation properties was observed.
Abstract: Advances technology in the field of photogrammetry
replaces analog cameras with reflection on aircraft GPS/IMU system
with a digital aerial camera. In this system, when determining the
position of the camera with the GPS, camera rotations are also
determined by the IMU systems. All around the world, digital aerial
cameras have been used for the photogrammetry applications in the
last ten years. In this way, in terms of the work done in
photogrammetry it is possible to use time effectively, costs to be
reduced to a minimum level, the opportunity to make fast and
accurate.
Geo-referencing techniques that are the cornerstone of the GPS /
INS systems, photogrammetric triangulation of images required for
balancing (interior and exterior orientation) brings flexibility to the
process. Also geo-referencing process; needed in the application of
photogrammetry targets to help to reduce the number of ground
control points. In this study, the use of direct and indirect georeferencing
techniques on the accuracy of the points was investigated
in the production of photogrammetric mapping.
Abstract: Diabetes is a growing health problem in worldwide.
Especially, the patients with Type 1 diabetes need strict glycemic
control because they have deficiency of insulin production. This
paper attempts to control blood glucose based on body mathematical
body model. The Bergman minimal mathematical model is used to
develop the nonlinear controller. A novel back-stepping based sliding
mode control (B-SMC) strategy is proposed as a solution that
guarantees practical tracking of a desired glucose concentration. In
order to show the performance of the proposed design, it is compared
with conventional linear and fuzzy controllers which have been done
in previous researches. The numerical simulation result shows the
advantages of sliding mode back stepping controller design to linear
and fuzzy controllers.
Abstract: Nonalcoholic fatty liver disease (NAFLD) has
increased in conjunction with obesity. The accuracy of risk factors
for detecting NAFLD in obese adolescents has not undergone a
formal evaluation. The aim of this study was to evaluate predictors of
NAFLD among Egyptian female obese adolescents. The study
included 162 obese female adolescents. All were subjected to
anthropometry, biochemical analysis and abdominal ultrasongraphic
assessment. Metabolic syndrome (MS) was diagnosed according to
the IDF criteria. Significant association between presence of MS and
NAFLD was observed. Obese adolescents with NAFLD had
significantly higher levels of ALT, triglycerides, fasting glucose,
insulin, blood pressure and HOMA-IR, whereas decreased HDL-C
levels as compared with obese cases without NAFLD. Receiver–
operating characteristic (ROC) curve analysis shows that ALT is a
sensitive predictor for NAFLD, confirming that ALT can be used as a
marker of NAFLD.
Abstract: Due to reduced stiffness, research on second
generation titanium alloys for implant applications, like the
metastable β-titanium alloy Ti-15Mo, become more and more
important in the recent years. The machinability of these alloys is
generally poor leading to problems during implant production and
comparably large production costs. Therefore, in the present study,
Ti-15Mo was alloyed with 0.8 wt.-% of the rare earth metals
lanthanum (Ti-15Mo+0.8La) and neodymium (Ti-15Mo+0.8Nd) to
improve its machinability. Their microstructure consisted of a
titanium matrix and micrometer-size particles of the rare earth metals
and two of their oxides. The particles stabilized the microstructure as
grain growth was minimized. As especially the ductility might be
affected by the precipitates, the behavior of Ti-15Mo+0.8La and Ti-
15Mo+0.8Nd was investigated during static and dynamic
deformation at elevated temperature to develop a processing route.
The resulting mechanical properties (static strength and ductility)
were similar in all investigated alloys.
Abstract: The success of any retail business is predisposed by its
swift response and its knack in understanding the constraints and the
requirements of customers. In this paper a conceptual design model
of an automated customer-friendly supermarket has been proposed.
In this model a 10-sided, space benefited, regular polygon shaped
gravity shelves have been designed for goods storage and effective
customer-specific algorithms have been built-in for quick automatic
delivery of the randomly listed goods. The algorithm is developed
with two main objectives, viz., delivery time and priority. For
meeting these objectives the randomly listed items are reorganized
according to the critical-path of the robotic arm specific to the
identified shop and its layout and the items are categorized according
to the demand, shape, size, similarity and nature of the product for an
efficient pick-up, packing and delivery process. We conjectured that
the proposed automated supermarket model reduces business
operating costs with much customer satisfaction warranting a winwin
situation.
Abstract: Economic Dispatch (ED) is one of the most
challenging problems of power system since it is difficult to determine
the optimum generation scheduling to meet the particular load demand
with the minimum fuel costs while all constraints are satisfied. The
objective of the Economic Dispatch Problems (EDPs) of electric
power generation is to schedule the committed generating units
outputs so as to meet the required load demand at minimum operating
cost while satisfying all units and system equality and inequality
constraints. In this paper, an efficient and practical steady-state genetic
algorithm (SSGAs) has been proposed for solving the economic
dispatch problem. The objective is to minimize the total generation
fuel cost and keep the power flows within the security limits. To
achieve that, the present work is developed to determine the optimal
location and size of capacitors in transmission power system where,
the Participation Factor Algorithm and the Steady State Genetic
Algorithm are proposed to select the best locations for the capacitors
and determine the optimal size for them.
Abstract: Rice straw pellets are a promising fuel as a renewable
energy source. Financial analysis is needed to make a utilization
system using rise straw pellets financially feasible, considering all
regional conditions including stakeholders related to the collection and
storage, production, transportation and heat utilization. We conducted
the financial analysis of feasibility for a heat utilization system using
rice straw pellets which has been developed for the first time in
Nanporo, Hokkaido, Japan. Especially, we attempted to clarify the
effect of factors required for the system to be financial feasibility, such
as the heating energy demand and collection and storage method of
rice straw. The financial feasibility was found to improve when
increasing the heating energy demand and collecting wheat straw in
August separately from collection of rice straw in November because
the costs of storing rice straw and producing pellets were reduced.
However, the system remained financially unfeasible. This study
proposed a contractor program funded by a subsidy from Nanporo
local government where a contracted company, instead of farmers,
collects and transports rice straw in order to ensure the financial
feasibility of the system, contributing to job creation in the region.
Abstract: Load carrying capacity of an oil lubricated two-axial
groove journal bearing is simulated by taking into account the
viscosity variations in lubricant due to the addition of TiO2
nanoparticles as lubricant additive. Shear viscosities of TiO2
nanoparticle dispersions in oil are measured for various nanoparticle
additive concentrations. The viscosity model derived from the
experimental viscosities is employed in a modified Reynolds
equation to obtain the pressure profiles and load carrying capacity of
two-axial groove journal bearing. Results reveal an increase in load
carrying capacity of bearings operating on nanoparticle dispersions as
compared to plain oil.
Abstract: This paper deals with the issue of biomass and sorted
municipal waste gasification and cogeneration using hot-air turbo-set.
It brings description of designed pilot plant with electrical output 80
kWe. The generated gas is burned in secondary combustion chamber
located beyond the gas generator. Flue gas flows through the heat
exchanger where the compressed air is heated and consequently
brought to a micro turbine. Except description, this paper brings our
basic experiences from operating of pilot plant (operating parameters,
contributions, problems during operating, etc.). The principal
advantage of the given cycle is the fact that there is no contact
between the generated gas and the turbine. So there is no need for
costly and complicated gas cleaning which is the main source of
operating problems in direct use in combustion engines because the
content of impurities in the gas causes operation problems to the units
due to clogging and tarring of working surfaces of engines and
turbines, which may lead as far as serious damage to the equipment
under operation. Another merit is the compact container package
making installation of the facility easier or making it relatively more
mobile. We imagine, this solution of cogeneration from biomass or
waste can be suitable for small industrial or communal applications,
for low output cogeneration.