Abstract: An active islanding detection method using disturbance signal injection with intelligent controller is proposed in this study. First, a DC\AC power inverter is emulated in the distributed generator (DG) system to implement the tracking control of active power, reactive power outputs and the islanding detection. The proposed active islanding detection method is based on injecting a disturbance signal into the power inverter system through the d-axis current which leads to a frequency deviation at the terminal of the RLC load when the utility power is disconnected. Moreover, in order to improve the transient and steady-state responses of the active power and reactive power outputs of the power inverter, and to further improve the performance of the islanding detection method, two probabilistic fuzzy neural networks (PFNN) are adopted to replace the traditional proportional-integral (PI) controllers for the tracking control and the islanding detection. Furthermore, the network structure and the online learning algorithm of the PFNN are introduced in detail. Finally, the feasibility and effectiveness of the tracking control and the proposed active islanding detection method are verified with experimental results.
Abstract: The exhaustion of oil and the environmental pollution from the use of fossil fuel are increasing. Tidal current power (TCP) has been proposed as an alternative energy source because of its predictability and reliability. By applying a duct and single point mooring (SPM) system, a TCP device can amplify the generating power and keep its position properly. Because the generating power is proportional to cube of the current stream velocity, amplifying the current speed by applying a duct to a TCP system is an effective way to improve the efficiency of the power device. An SPM system can be applied at any water depth and is highly cost effective. Simple installation and maintenance procedures are also merits of an SPM system. In this study, we designed an SPM system for a duct-type TCP device for use in shallow water. Motions of the duct are investigated to obtain the response amplitude operator (RAO) as the magnitude of the transfer function. Parameters affecting the stability of the SPM system such as the fairlead departure angle, current velocity, and the number of clamp weights are analyzed and/or optimized. Wadam and OrcaFlex commercial software is used to design the mooring line.
Abstract: Marble industry contributes its fair share in environmental deterioration, producing voluminous amounts of mud and other excess residues obtained from marble and granite processing, polluting soil, water and air. Reusing these products in other products will not just prevent our environment from polluting but also help with economy. In this research, an attempt has been made to study the expediency of waste Marble Powder (MP) in concrete production. Various laboratory tests were performed to investigate permeability, physical and mechanical properties, such as slump, compressive strength, split tensile test, etc. Concrete test samples were fabricated with varying MP content (replacing 5-30% cement), furnished from two different sources. 5% replacement of marble dust caused 6% and 12% decrease in compressive and tensile strength respectively. These parameters gradually decreased with increasing MP content up to 30%. Most optimum results were obtained with 10% replacement. Improvement in consistency and permeability were noticed. The permeability was improved with increasing MP proportion up to 10% without substantial decrease in compressive strength. Obtained results revealed that MP as an alternative to cement in concrete production is a viable option considering its economic and environment friendly implications.
Abstract: The objectives of this research were to study the level
of influencing factors, leadership, supply chain management,
innovation, competitive advantages, business success, and affecting
factors to the business success of the mobile phone system service
providers in Bangkok Metropolitan. This research was done by the
quantitative approach and the qualitative approach. The quantitative
approach was used for questionnaires to collect data from the 331
mobile service shop managers franchised by AIS, Dtac and
TrueMove. The mobile phone system service providers/shop
managers were randomly stratified and proportionally allocated into
subgroups exclusive to the number of the providers in each network.
In terms of qualitative method, there were in-depth interviews of 6
mobile service providers/managers of Telewiz and Dtac and
TrueMove shop to find the agreement or disagreement with the
content analysis method. Descriptive Statistics, including Frequency,
Percentage, Means and Standard Deviation were employed; also, the
Structural Equation Model (SEM) was used as a tool for data
analysis. The content analysis method was applied to identify key
patterns emerging from the interview responses. The two data sets
were brought together for comparing and contrasting to make the
findings, providing triangulation to enrich result interpretation. It
revealed that the level of the influencing factors – leadership,
innovation management, supply chain management, and business
competitiveness had an impact at a great level, but that the level of
factors, innovation and the business, financial success and nonbusiness
financial success of the mobile phone system service
providers in Bangkok Metropolitan, is at the highest level. Moreover,
the business influencing factors, competitive advantages in the
business of mobile system service providers which were leadership,
supply chain management, innovation management, business
advantages, and business success, had statistical significance at .01
which corresponded to the data from the interviews.
Abstract: Ultrasonic pulse velocity (UPV) method has been shown for some time to provide a reliable means of estimating properties and offers a unique opportunity for direct, quick and safe control of building damaged by earthquake, fatigue, conflagration and catastrophic scenarios. On this investigation hybrid reinforced concrete has been investigated by UPV method. Hooked end steel fiber of length 50 and 30 mm was added to concrete in different proportion 0, 0.25, 0.5, and 1 % by the volume of concrete. On the other hand, polypropylene fiber of length 12, 6, 3 mm was added to concrete of 0.1, 0.2, and 0.4 % by the volume of concrete. Fifteen different mixture has been prepared to investigate the relation between compressive strength and UPV values and also to investigate on the effect of volume and type of fiber on UPV values.
Abstract: Flexible satellites are equipped with various appendages which vibrate under the influence of any excitation and make the attitude of the satellite to be unstable. Therefore, the system must be able to adjust to balance the effect of these appendages in order to point accurately and satisfactorily which is one of the most important problems in satellite design. Proportional Integral Derivative (PID) Controller is simple to design and computationally efficient to implement which is used to stabilize the effect of these flexible appendages. However, manual turning of the PID is time consuming, waste energy and money. Particle Swarm Optimization (PSO) is used to tune the parameters of PID Controller. Simulation results obtained show that PSO tuned PID Controller is able to re-orient the spacecraft attitude as well as dampen the effect of mechanical resonance and yields better performance when compared with manually tuned PID Controller.
Abstract: The alternating current is the main power in all industries and other aspects especially for the short and mid distances, but as far as long a distance which exceeds 500 KMs, using the alternating current technically will face many difficulties and more costs because it's difficult to control the current and also other restrictions. Therefore, recently those reasons led to building transmission lines HVDC to transmit power for long distances. This document presents technical comparison and assessments for power transmission system among distances either ways and studying the stability of the system regarding the proportion of losses in the actual power sent and received between both sides in different systems and also categorizing filters used in the HVDC system and its impact and effect on reducing Harmonic in the power transmission. MATLAB /Simulink simulation software is used to simulate both HVAC & HVDC power transmission system topologies.
Abstract: The great majority of the applications of thermal isolation in the strip of drops and averages temperatures (up to 200ºC), it is made of materials aggressive nature, such an as glass wool, rock wool, polystyrene, EPS among others. Such materials, in spite of the effectiveness in the retention of the flow of heat, possess considerable cost and when discarded they are long years to be to decompose. In that context, trying to adapt the world politics the about of the preservation of the environment, a study began with intention of developing a material composite, with properties of thermal, originating from insulating industrial residues. In this research, the behavior of the composite was analyzed, as submitted the fire. For this, the reaction rehearsals were accomplished to the fire for the composites 2:1; 1:1; 1:2 and for the Latex, based in the "con" experiment in agreement with the norm ASTM - E 1334 - 90. As consequence, in function of the answers of the system was possible to be observed to the acting of each mixture proportion.
Abstract: Effective treatment of ground instability is essential when managing the impacts associated with historic mining. A field trial was undertaken by the Coal Authority to investigate the geotechnical performance and potential use of composite materials comprising resin and fill or stone to safely treat surface collapses, such as crown-holes, associated with shallow mining. Test pits were loosely filled with various granular fill materials. The fill material was injected with commercially available silicate and polyurethane resin foam products. In situ and laboratory testing was undertaken to assess the geotechnical properties of the resultant composite materials. The test pits were subsequently excavated to assess resin permeation. Drilling and resin injection was easiest through clean limestone fill materials. Recycled building waste fill material proved difficult to inject with resin; this material is thus considered unsuitable for use in resin composites. Incomplete resin permeation in several of the test pits created irregular ‘blocks’ of composite. Injected resin foams significantly improve the stiffness and resistance (strength) of the un-compacted fill material. The stiffness of the treated fill material appears to be a function of the stone particle size, its associated compaction characteristics (under loose tipping) and the proportion of resin foam matrix. The type of fill material is more critical than the type of resin to the geotechnical properties of the composite materials. Resin composites can effectively support typical design imposed loads. Compared to other traditional treatment options, such as cement grouting, the use of resin composites is potentially less disruptive, particularly for sites with limited access, and thus likely to achieve significant reinstatement cost savings. The use of resin composites is considered a suitable option for the future treatment of shallow mining collapses.
Abstract: In the knowledge-based economy, innovation is considered essential in order to achieve survival and growth in organizations. On the other hand, knowledge management is currently understood as one of the keys to innovation process. Both factors are generally admitted as generators of competitive advantage in organizations. Specifically, activities on R&D&I and those that generate internal knowledge have a positive influence in innovation results. This paper examines this effect and if it is similar or not is what we aimed to quantify in this paper. We focus on the impact that proportion of knowledge workers, the R&D&I investment, the amounts destined for ICTs and training for innovation have on the variation of tangible and intangibles returns for the sector of high and medium technology in Spain. To do this, we have performed an empirical analysis on the results of questionnaires about innovation in enterprises in Spain, collected by the National Statistics Institute. First, using clusters methodology, the behavior of these enterprises regarding knowledge management is identified. Then, using SEM methodology, we performed, for each cluster, the study about cause-effect relationships among constructs defined through variables, setting its type and quantification. The cluster analysis results in four groups in which cluster number 1 and 3 presents the best performance in innovation with differentiating nuances among them, while clusters 2 and 4 obtained divergent results to a similar innovative effort. However, the results of SEM analysis for each cluster show that, in all cases, knowledge workers are those that affect innovation performance most, regardless of the level of investment, and that there is a strong correlation between knowledge workers and investment in knowledge generation. The main findings reached is that Spanish high and medium technology companies improve their innovation performance investing in internal knowledge generation measures, specially, in terms of R&D activities, and underinvest in external ones. This, and the strong correlation between knowledge workers and the set of activities that promote the knowledge generation, should be taken into account by managers of companies, when making decisions about their investments for innovation, since they are key for improving their opportunities in the global market.
Abstract: The power buck converter is the most widely used
DC/DC converter topology. They have a very large application area
such as DC motor drives, photovoltaic power system which require
fast transient responses and high efficiency over a wide range of load
current. This work proposes, the modelling of DC/DC power buck
converter using state-space averaging method and the current-mode
control using a proportional-integral controller. The efficiency of the
proposed model and control loop are evaluated with operating point
changes. The simulation results proved the effectiveness of the linear
model of DC/DC power buck converter.
Abstract: The inverted pendulum system is a classic control
problem that is used in universities around the world. It is a suitable
process to test prototype controllers due to its high non-linearities and
lack of stability. The inverted pendulum represents a challenging
control problem, which continually moves toward an uncontrolled
state. This paper presents the possibility of balancing an inverted
pendulum system using sliding mode control (SMC). The goal is to
determine which control strategy delivers better performance with
respect to pendulum’s angle and cart's position. Therefore,
proportional-integral-derivative (PID) is used for comparison. Results
have proven SMC control produced better response compared to PID
control in both normal and noisy systems.
Abstract: This paper proposes an APPLE scheme that aims at providing absolute and proportional throughput guarantees, and maximizing system throughput simultaneously for wireless LANs with homogeneous and heterogenous traffic. We formulate our objectives as an optimization problem, present its exact and approximate solutions, and prove the existence and uniqueness of the approximate solution. Simulations validate that APPLE scheme is accurate, and the approximate solution can well achieve the desired objectives already.
Abstract: Customer’ needs, quality, and value creation while
reducing costs through supply chain management provides challenges
and opportunities for companies and researchers. In the light of these
challenges, modern ideas must contribute to counter these challenges
and exploit opportunities. Therefore, this paper discusses the impact
of the quality cost on revenue sharing as a most important incentive
to configure business networks. This paper develops the quality cost approach to align with the
modern era. It develops a model to measure quality costs which
might enable firms to manage revenue sharing in a supply chain. The
developed model includes five categories; besides the well-known
four categories (namely prevention costs, appraisal costs, internal
failure costs, and external failure costs), a new category has been
developed in this research as a new vision of the relationship between
quality costs and innovations in industry. This new category is
Recycle Cost. This paper also examines whether such quality costs in
supply chains influence the revenue sharing between partners. Using the author's quality cost model, the relationship between
quality costs and revenue sharing among partners is examined using a
case study in an Egyptian manufacturing company which is a part of
a supply chain. This paper argues that the revenue-sharing proportion
allocated to supplier increases as the recycle cost of supplier
increases, and the revenue-sharing proportion allocated to
manufacturer increases as the prevention and appraisal costs increase,
as well as the failure costs, the recycle costs of manufacturer, and the
recycle costs of suppliers decrease. However, the results present
surprising findings. The purposes of this study are developing quality cost approach
and understanding the relationships between quality costs and
revenue sharing in supply chains. Therefore, the present study
contributes to theory and practice by explaining how the cost of
recycling can be combined in quality cost model to better
understanding the revenue sharing among partners in supply chains.
Abstract: Response Surface Methods (RSM) provide
statistically validated predictive models that can then be manipulated
for finding optimal process configurations. Variation transmitted to
responses from poorly controlled process factors can be accounted
for by the mathematical technique of propagation of error (POE),
which facilitates ‘finding the flats’ on the surfaces generated by
RSM. The dual response approach to RSM captures the standard
deviation of the output as well as the average. It accounts for
unknown sources of variation. Dual response plus propagation of
error (POE) provides a more useful model of overall response
variation. In our case, we implemented this technique in predicting
compressive strength of concrete of 28 days in age. Since 28 days is
quite time consuming, while it is important to ensure the quality
control process. This paper investigates the potential of using design
of experiments (DOE-RSM) to predict the compressive strength of
concrete at 28th day. Data used for this study was carried out from
experiment schemes at university of Benghazi, civil engineering
department. A total of 114 sets of data were implemented. ACI mix
design method was utilized for the mix design. No admixtures were
used, only the main concrete mix constituents such as cement, coarseaggregate,
fine aggregate and water were utilized in all mixes.
Different mix proportions of the ingredients and different water
cement ratio were used. The proposed mathematical models are
capable of predicting the required concrete compressive strength of
concrete from early ages.
Abstract: A retrospective study conducted at Christian Medical
College (CMC) Teaching Hospital, Vellore, India on 14th August
2014 to assess the accuracy of clinically estimated foetal weight upon
labour admission. Estimating foetal weight is a crucial factor in
assessing maternal and foetal complications during and after labour.
Medical notes of ninety-eight postnatal women who fulfilled the
inclusion criteria were studied to evaluate the correlation between
their recorded Estimated Foetal Weight (EFW) on admission and
actual birth weight (ABW) of the newborn after delivery. Data
concerning maternal and foetal demographics was also noted.
Accuracy was determined by absolute percentage error and
proportion of estimates within 10% of ABW. Actual birth weights
ranged from 950-4080g. A strong positive correlation between EFW
and ABW (r=0.904) was noted. Term deliveries (≥40 weeks) in the
normal weight range (2500-4000g) had a 59.5% estimation accuracy
(n=74) compared to pre-term (4000g) were underestimated by 25% (n=3) and low birthweight
(LBW) babies were overestimated by 12.7% (n=9). Registrars who
estimated foetal weight were accurate in babies within normal weight
ranges. However, there needs to be an improvement in predicting
weight of macrosomic and LBW foetuses. We have suggested the use
of an amended version of the Johnson’s formula for the Indian
population for improvement and a need to re-audit once
implemented.
Abstract: Background: To compare the thinning patterns of the
ganglion cell-inner plexiform layer (GCIPL) and peripapillary retinal
nerve fiber layer (pRNFL) as measured using Cirrus high-definition
optical coherence tomography (HD-OCT) in patients with visual field
(VF) defects that respect the vertical meridian. Methods: Twenty eyes of eleven patients with VF defects that
respect the vertical meridian were enrolled retrospectively. The
thicknesses of the macular GCIPL and pRNFL were measured using
Cirrus HD-OCT. The 5% and 1% thinning area index (TAI) was
calculated as the proportion of abnormally thin sectors at the 5% and
1% probability level within the area corresponding to the affected VF.
The 5% and 1% TAI were compared between the GCIPL and pRNFL
measurements. Results: The color-coded GCIPL deviation map showed a
characteristic vertical thinning pattern of the GCIPL, which is also
seen in the VF of patients with brain lesions. The 5% and 1% TAI
were significantly higher in the GCIPL measurements than in the
pRNFL measurements (all P < 0.01). Conclusions: Macular GCIPL analysis clearly visualized a
characteristic topographic pattern of retinal ganglion cell (RGC) loss
in patients with VF defects that respect the vertical meridian, unlike
pRNFL measurements. Macular GCIPL measurements provide more
valuable information than pRNFL measurements for detecting the
loss of RGCs in patients with retrograde degeneration of the optic
nerve fibers.
Abstract: Household waste form a larger proportion of waste
generated across the state, accumulation of organic waste is an
apparent problem and the existing dump sites could be overstress.
Niger state has abundant arable land and water resources thus should
be one of the highest producers of agricultural crops in the country.
However, the major challenge to agricultural sector today is loss of
soil nutrient coupled with high cost of fertilizer. These have
continued to increase the use of fertilizer and decomposed solid waste
for enhance agricultural yield, which have varying effects on the soil
as well a threat to human livelihood. Consequently, vegetable yield
samples from poultry droppings, decomposed household waste
manure, NPK treatments and control from each replication were
subjected to proximate analysis to determine the nutritional and antinutritional
component as well as heavy metal concentration. Data
collected was analyzed using SPSS software and Randomized
complete Block Design means were compared. The result shows that
the treatments do not devoid the concentrations of any nutritional
components while the anti-nutritional analysis proved that NPK had
higher oxalate content than control and organic treats. The
concentration of lead and cadmium are within safe permissible level
while the mercury level exceeded the FAO/WHO maximum
permissible limit for the entire treatments depicts the need for urgent
intervention to minimize mercury levels in soil and manure in order
to mitigate its toxic effect. Thus, eco-agriculture should be widely
accepted and promoted by the stakeholders for soil amendment,
higher yield, strategies for sustainable environmental protection, food
security, poverty eradication, attainment of sustainable development
and healthy livelihood.
Abstract: The need to save time and cost of soil testing at the
planning stage of road work has necessitated developing predictive
models. This study proposes a model for predicting the dry density of
lateritic soils stabilized with corn cob ash (CCA) and blended cement
- CCA. Lateritic soil was first stabilized with CCA at 1.5, 3.0, 4.5 and
6% of the weight of soil and then stabilized with the same
proportions as replacement for cement. Dry density, specific gravity,
maximum degree of saturation and moisture content were determined
for each stabilized soil specimen, following standard procedure.
Polynomial equations containing alpha and beta parameters for CCA
and blended CCA-cement were developed. Experimental values were
correlated with the values predicted from the Matlab curve fitting
tool, and the Solver function of Microsoft Excel 2010. The correlation
coefficient (R2) of 0.86 was obtained indicating that the model could
be accepted in predicting the maximum dry density of CCA stabilized
soils to facilitate quick decision making in roadworks.
Abstract: Rice Husk (RH) is the major byproduct in the
processing of paddy rice. The management of this waste has become
a big challenge to some of the rice producers, some of these wastes
are left in open dumps while some are burn in the open space, and
these two actions have been contributing to environmental pollution.
This study evaluates an alternative waste management of this
agricultural product for use as a civil engineering material. The RH
was burn in a controlled environment to form Rice Husk Ash (RHA).
The RHA was mix with lateritic clay at 0, 2, 4, 6, 8, and 10%
proportion by weight. Chemical test was conducted on the open burn
and controlled burn RHA with the lateritic clay. Physical test such as
particle size distribution, Atterberg limits test, and density test were
carried out on the mix material. The chemical composition obtained
for the RHA showed that the total percentage compositions of Fe2O3,
SiO2 and Al2O3 were found to be above 70% (class “F” pozzolan)
which qualifies it as a very good pozzolan. The coefficient of
uniformity (Cu) was 8 and coefficient of curvature (Cc) was 2 for the
soil sample. The Plasticity Index (PI) for the 0, 2, 4, 6, 8. 10% was
21.0, 18.8, 16.7, 14.4, 12.4 and 10.7 respectively. The work
concluded that RHA can be effectively used in hydraulic barriers and
as a stabilizing agent in soil stabilization.