Abstract: Power systems and transformer are intrinsic apparatus, therefore its reliability and safe operation is important to determine their operation conditions, and the industry uses quality control tests in the insulation design of oil filled transformers. Hence the service period effect on AC dielectric strength is significant. The effect of aging on transformer oil physical, chemical and electrical properties was studied using the international testing methods for the evaluation of transformer oil quality. The study was carried out on six transformers operate in the field and for monitoring periods over twenty years. The properties which are strongly time dependent were specified and those which have a great impact on the transformer oil acidity, breakdown voltage and dissolved gas analysis were defined. Several tests on the transformers oil were studied to know the time of purifying or changing it, moreover prediction of the characteristics of it under different operation conditions.
Abstract: Manufacturing tolerancing is intended to determine
the intermediate geometrical and dimensional states of the part
during its manufacturing process. These manufacturing dimensions
also serve to satisfy not only the functional requirements given in
the definition drawing, but also the manufacturing constraints, for
example geometrical defects of the machine, vibration and the
wear of the cutting tool. In this paper, an experimental study on the
influence of the wear of the cutting tool (systematic dispersions) is
explored. This study was carried out on three stages .The first stage
allows machining without elimination of dispersions (random,
systematic) so the tolerances of manufacture according to total
dispersions. In the second stage, the results of the first stage are
filtered in such way to obtain the tolerances according to random
dispersions. Finally, from the two previous stages, the systematic
dispersions are generated. The objective of this study is to model
by the least squares method the error of manufacture based on
systematic dispersion. Finally, an approach of optimization of the
manufacturing tolerances was developed for machining on a CNC
machine tool
Abstract: In construction of any structure, the aesthetic and utility values should be considered in such a way as to make the structure cost-effective. Most structures are composed of elements and joints which are very critical in any skeletal space structure because they majorly determine the performance of the structure. In early times, most space structures were constructed using rigid joints which had the advantage of better performing structures as compared to pin-jointed structures but with the disadvantage of requiring all the construction work to be done on site. The discovery of semi-rigid joints now enables connections to be prefabricated and quickly assembled on site while maintaining good performance. In this paper, cost-effective is discussed basing on strength of connectors at the joints, buckling of joints and overall structure, and the effect of initial geometrical imperfections. Several existing joints are reviewed by classifying them into categories and discussing where they are most suited and how they perform structurally. Also, finite element modeling using ABAQUS is done to determine the buckling behavior. It is observed that some joints are more economical than others. The rise to span ratio and imperfections are also found to affect the buckling of the structures. Based on these, general principles that guide the design of cost-effective joints and structures are discussed.
Abstract: This paper describes the application of a model predictive controller to the problem of batch reactor temperature control. Although a great deal of work has been done to improve reactor throughput using batch sequence control, the control of the actual reactor temperature remains a difficult problem for many operators of these processes. Temperature control is important as many chemical reactions are sensitive to temperature for formation of desired products. This controller consist of two part (1) a nonlinear control method GLC (Global Linearizing Control) to create a linear model of system and (2) a Model predictive controller used to obtain optimal input control sequence. The temperature of reactor is tuned to track a predetermined temperature trajectory that applied to the batch reactor. To do so two input signals, electrical powers and the flow of coolant in the coil are used. Simulation results show that the proposed controller has a remarkable performance for tracking reference trajectory while at the same time it is robust against noise imposed to system output.
Abstract: The purpose of the study was to determine the amount of Palm Kernel Oil (PKO) extracted from a packed bed of palm kernels in a supercritical fluid extractor using supercritical carbon dioxide (SC-CO2) as an environmental friendly solvent. Further, the study sought to ascertain the values of the overall mass transfer coefficient (K) of PKO evaluation through a mass transfer model, at constant temperature of 50 °C, 60 °C, and 70 °C and pressures range from 27.6 MPa, 34.5 MPa, 41.4 MPa and 48.3 MPa respectively. Finally, the study also seeks to demonstrate the application of the overall mass transfer coefficient values in relation to temperature and pressure. The overall mass transfer coefficient was found to be dependent pressure at each constant temperature of 50 °C, 60 °C and 70 °C. The overall mass transfer coefficient for PKO in a packed bed of palm kernels was found to be in the range of 1.21X 10-4 m min-1 to 1.72 X 10-4 m min-1 for a constant temperature of 50 °C and in the range of 2.02 X 10-4 m min-1 to 2.43 X 10-4 m min-1 for a constant temperature of 60 °C. Similar increasing trend of the overall mass transfer coefficient from 1.77 X 10-4 m min-1 to 3.64 X 10-4 m min-1 was also observed at constant temperature of 70 °C within the same pressure range from 27.6 MPa to 48.3 MPa.
Abstract: This paper examines the forced convection flow of
incompressible, electrically conducting viscous fluid past a sharp
wedge in the presence of heat generation or absorption with an
applied magnetic field. The system of partial differential equations
governing Falkner - Skan wedge flow and heat transfer is first
transformed into a system of ordinary differential equations using
similarity transformations which is later solved using an implicit
finite - difference scheme, along with quasilinearization technique.
Numerical computations are performed for air (Pr = 0.7) and
displayed graphically to illustrate the influence of pertinent physical
parameters on local skin friction and heat transfer coefficients and,
also on, velocity and temperature fields. It is observed that the
magnetic field increases both the coefficients of skin friction and heat
transfer. The effect of heat generation or absorption is found to be
very significant on heat transfer, but its effect on the skin friction is
negligible. Indeed, the occurrence of overshoot is noticed in the
temperature profiles during heat generation process, causing the
reversal in the direction of heat transfer.
Abstract: Mushrooms are a group of fleshy macroscopic fungi.
They have been valued throughout the world as both edible and
medicine. They are highly nutritious with good amount of quality
proteins, vitamins and minerals. An edible mushroom, Calocybe
indica was selected to validate its nutritional and medicinal
properties. Since tissue damage in hyperglycemia has been related to
oxidative stress, we evaluated the enzymatic and non-enzymatic
antioxidant status in the serum, liver and kidney since they are the
target organs in diabetic complications. From the results, increased
oxidative stress and decreased antioxidants might be related to the
causation of diabetes mellitus. The treatment in the diabetic rats with
the Calocybe indica showed an increase in the antioxidant system
and decrease in the production of free radicals. The mushrooms
which contain antioxidant phytochemicals has potential free radical
scavenging capacity and hence can induce the antioxidant system in
the body significantly reduces the generated free radicals thereby
maintaining the normal levels of the antioxidants
Abstract: This paper presents a practical scheme that can be used for allocating the transmission loss to generators and loads. In this scheme first the share of a generator or load on the current through a branch is determined using Z-bus modified matrix. Then the current components are decomposed and the branch loss allocation is obtained. A motivation of proposed scheme is to improve the results of Z-bus method and to reach more fair allocation. The proposed scheme has been implemented and tested on several networks. To achieve practical and applicable results, the proposed scheme is simulated and compared on the transmission network (400kv) of Khorasan region in Iran and the 14-bus standard IEEE network. The results show that the proposed scheme is comprehensive and fair to allocating the energy losses of a power market to its participants.
Abstract: Disposal of health-care waste (HCW) is considered as
an important environmental problem especially in large cities.
Multiple criteria decision making (MCDM) techniques are apt to deal
with quantitative and qualitative considerations of the health-care
waste management (HCWM) problems. This research proposes a
fuzzy multi-criteria group decision making approach with a multilevel
hierarchical structure including qualitative as well as
quantitative performance attributes for evaluating HCW disposal
alternatives for Istanbul. Using the entropy weighting method,
objective weights as well as subjective weights are taken into account
to determine the importance weighting of quantitative performance
attributes. The results obtained using the proposed methodology are
thoroughly analyzed.
Abstract: The game of Maundy Block is the three-player variant
of Maundy Cake, a classical combinatorial game. Even though to
determine the solution of Maundy Cake is trivial, solving Maundy
Block is challenging because of the identification of queer games,
i.e., games where no player has a winning strategy.
Abstract: Low carbon deep drawing steel DC 01 according to EN 10130-91 was nitrooxidized in dissociated ammonia at 580°C/45 min and consequently oxidised at 380°C/5 min in vapour of distilled water. Material after nitrooxidation had 54 % increase of yield point, 34 % increase of strength and 10-times increased resistance to atmospheric corrosion in comparison to the material before nitrooxidation. The microstructure of treated material consisted of thin ε-phase layer connected to layer containing precipitated massive needle shaped Fe4N - γ' nitrides. This layer passed to a diffusion layer consisting of fine irregular shaped Fe16N2 - α'' nitrides regularly dispersed in ferritic matrix. Fatigue properties were examined under bending load with frequency of 20 kHz and sinusoidal symmetric cycle. The results confirmed positive influence of nitrooxidation on fatigue properties as fatigue limit of treated material was double in comparison to untreated material.
Abstract: This study examined the effects of two dynamic
visualizations on 60 Malaysian primary school student-s performance
(time on task), retention and transference. The independent variables
in this study were the two dynamic visualizations, the video and the
animated instructions. The dependent variables were the gain score of
performance, retention and transference. The results showed that the
students in the animation group significantly outperformed the
students in the video group in retention. There were no significant
differences in terms of gain scores in the performance and
transference among the animation and the video groups, although the
scores were slightly higher in the animation group compared to the
video group. The conclusion of this study is that the animation
visualization is superior compared to the video in the retention for a
procedural task.
Abstract: Global climate change has become the preeminent
threat to human security in the 21st century. From mitigation perspective, this study aims to evaluate the performance of biogas
renewable project under clean development mechanism activities
(namely Korat-Waste-to-Energy) in Thailand and to assess local perceptions towards the significance of climate change mitigation and
sustainability of such project in their community. Questionnaire was
developed based on the national sustainable development criteria and
was distributed among systematically selected households within
project boundaries (n=260). Majority of the respondents strongly agreed with the reduction of odor problems (81%) and air pollution
(76%). However, they were unsure about greenhouse gas reduction from such project and ignorant about the key issues of climate change. A lesson learned suggested that there is a need to further
investigate the possible socio-psychological barriers may significantly shape public perception and understandings of climate
change in the local context.
Abstract: Full adders are important components in applications
such as digital signal processors (DSP) architectures and
microprocessors. In addition to its main task, which is adding two
numbers, it participates in many other useful operations such as
subtraction, multiplication, division,, address calculation,..etc. In
most of these systems the adder lies in the critical path that
determines the overall speed of the system. So enhancing the
performance of the 1-bit full adder cell (the building block of the
adder) is a significant goal.Demands for the low power VLSI have
been pushing the development of aggressive design methodologies to
reduce the power consumption drastically. To meet the growing
demand, we propose a new low power adder cell by sacrificing the
MOS Transistor count that reduces the serious threshold loss
problem, considerably increases the speed and decreases the power
when compared to the static energy recovery full (SERF) adder. So a
new improved 14T CMOS l-bit full adder cell is presented in this
paper. Results show 50% improvement in threshold loss problem,
45% improvement in speed and considerable power consumption
over the SERF adder and other different types of adders with
comparable performance.
Abstract: Despite the availability of natural disaster related time series data for last 110 years, there is no forecasting tool available to humanitarian relief organizations to determine forecasts for emergency logistics planning. This study develops a forecasting tool based on identifying probability distributions. The estimates of the parameters are used to calculate natural disaster forecasts. Further, the determination of aggregate forecasts leads to efficient pre-disaster planning. Based on the research findings, the relief agencies can optimize the various resources allocation in emergency logistics planning.
Abstract: Effects of bio-nitrogen fertilizer (bio-N), as a partial
alternative to mineral-nitrogen fertilizer (mineral-N), on growth,
yield and yield quality of broccoli plants were investigated. Bio-N
was applied at 1, 2 or 3 doses in combination with 65% of the
recommended dose of mineral-N (bio-N1, bio-N2 or bio-N3 +
⅔mineral-N). However, 100% of the recommended dose of mineral-
N was applied as a control. Significant positive influences of the bio-
N3 + ⅔mineral-N treatment were observed on growth traits, leaf
contents of nitrogen, phosphorus, potassium, nitrate and nitrite, and
yield quality when compared to the other two combined treatments.
In contrast, there were no significant differences in these parameters
between the bio-N3 + ⅔mineral-N and the control treatments, except
for leaf contents of nitrate and nitrite. They showed lower contents in
the bio-N3 + ⅔mineral-N treatment than the control. Therefore, we
recommend using bio-N as a partial alternative to mineral-N for
healthy nutrition.
Abstract: There are reports of gas and oil wells fire due to different accidents. Many different methods are used for fire fighting in gas and oil industry. Traditional fire extinguishing techniques are mostly faced with many problems and are usually time consuming and needs lots of equipments. Besides, they cause damages to facilities, and create health and environmental problems. This article proposes innovative approach in fire extinguishing techniques in oil and gas industry, especially applicable for burning oil wells located offshore. Fire extinguishment employing a turbojet is a novel approach which can help to extinguishment the fire in short period of time. Divergent and convergent turbojets modeled in laboratory scale along with a high pressure flame were used. Different experiments were conducted to determine the relationship between output discharges of trumpet and oil wells. The results were corrected and the relationship between dimensionless parameters of flame and fire extinguishment distances and also the output discharge of turbojet and oil wells in specified distances are demonstrated by specific curves.
Abstract: Not many studies have been undertaken on shareholder activism in emerging economies, including Malaysia. Shareholder activism in emerging economies is on the rise. This paper seeks to comprehend the elements of this activism that are unique to Malaysia, specifically with respect to how the agency problem is controlled through shareholder activism in improving corporate governance practices within target companies. Through shareholder activism, shareholders make contact with a target company to voice their dissatisfaction, suggestions, or recommendations. This paper utilises agency theory to explain institutional shareholder activism. This theory has been extensively used within literature on corporate governance with regards to shareholder activism. The effectiveness of shareholder activism in improving corporate governance will be examined as well. This research provides a further understanding of shareholder activism in emerging economies, such as Malaysia; this research also has the potential to enhance shareholder activism and corporate governance practices in general.
Abstract: The electrolyte stirring method of anodization etching
process for manufacturing porous silicon (PS) is reported in this work.
Two experimental setups of nature air stirring (PS-ASM) and
electrolyte stirring (PS-ESM) are employed to clarify the influence of
stirring mechanisms on electrochemical etching process. Compared to
traditional fabrication without any stirring apparatus (PS-TM), a large
plateau region of PS surface structure is obtained from samples with
both stirring methods by the 3D-profiler measurement. Moreover, the
light emission response is also improved by both proposed electrolyte
stirring methods due to the cycling force in electrolyte could
effectively enhance etch-carrier distribution while the electrochemical
etching process is made. According to the analysis of statistical
calculation of photoluminescence (PL) intensity, lower standard
deviations are obtained from PS-samples with studied stirring methods,
i.e. the uniformity of PL-intensity is effectively improved. The
calculated deviations of PL-intensity are 93.2, 74.5 and 64,
respectively, for PS-TM, PS-ASM and PS-ESM.
Abstract: The potential of economically cheaper cellulose
containing natural materials like rice husk was assessed for nickel
adsorption from aqueous solutions. The effects of pH, contact time,
sorbent dose, initial metal ion concentration and temperature on the
uptake of nickel were studied in batch process. The removal of nickel
was dependent on the physico-chemical characteristics of the
adsorbent, adsorbate concentration and other studied process
parameters. The sorption data has been correlated with Langmuir,
Freundlich and Dubinin-Radush kevich (D-R) adsorption models. It
was found that Freundlich and Langmuir isotherms fitted well to the
data. Maximum nickel removal was observed at pH 6.0. The
efficiency of rice husk for nickel removal was 51.8% for dilute
solutions at 20 g L-1 adsorbent dose. FTIR, SEM and EDAX were
recorded before and after adsorption to explore the number and
position of the functional groups available for nickel binding on to
the studied adsorbent and changes in surface morphology and
elemental constitution of the adsorbent. Pseudo-second order model
explains the nickel kinetics more effectively. Reusability of the
adsorbent was examined by desorption in which HCl eluted 78.93%
nickel. The results revealed that nickel is considerably adsorbed on
rice husk and it could be and economic method for the removal of
nickel from aqueous solutions.