416 research outputs found
Swarm Intelligence Based Multi-phase OPF For Peak Power Loss Reduction In A Smart Grid
Recently there has been increasing interest in improving smart grids
efficiency using computational intelligence. A key challenge in future smart
grid is designing Optimal Power Flow tool to solve important planning problems
including optimal DG capacities. Although, a number of OPF tools exists for
balanced networks there is a lack of research for unbalanced multi-phase
distribution networks. In this paper, a new OPF technique has been proposed for
the DG capacity planning of a smart grid. During the formulation of the
proposed algorithm, multi-phase power distribution system is considered which
has unbalanced loadings, voltage control and reactive power compensation
devices. The proposed algorithm is built upon a co-simulation framework that
optimizes the objective by adapting a constriction factor Particle Swarm
optimization. The proposed multi-phase OPF technique is validated using IEEE
8500-node benchmark distribution system.Comment: IEEE PES GM 2014, Washington DC, US
Enhanced Estimation of Autoregressive Wind Power Prediction Model Using Constriction Factor Particle Swarm Optimization
Accurate forecasting is important for cost-effective and efficient monitoring
and control of the renewable energy based power generation. Wind based power is
one of the most difficult energy to predict accurately, due to the widely
varying and unpredictable nature of wind energy. Although Autoregressive (AR)
techniques have been widely used to create wind power models, they have shown
limited accuracy in forecasting, as well as difficulty in determining the
correct parameters for an optimized AR model. In this paper, Constriction
Factor Particle Swarm Optimization (CF-PSO) is employed to optimally determine
the parameters of an Autoregressive (AR) model for accurate prediction of the
wind power output behaviour. Appropriate lag order of the proposed model is
selected based on Akaike information criterion. The performance of the proposed
PSO based AR model is compared with four well-established approaches;
Forward-backward approach, Geometric lattice approach, Least-squares approach
and Yule-Walker approach, that are widely used for error minimization of the AR
model. To validate the proposed approach, real-life wind power data of
\textit{Capital Wind Farm} was obtained from Australian Energy Market Operator.
Experimental evaluation based on a number of different datasets demonstrate
that the performance of the AR model is significantly improved compared with
benchmark methods.Comment: The 9th IEEE Conference on Industrial Electronics and Applications
(ICIEA) 201
A multi-physics simulation approach to Investigating the underlying mechanisms of Low-Speed Pre-Ignition
As part of the effort to improve thermal efficiency, engines are being
significantly downsized. A common issue in gasoline engines which limits
thermal efficiency and is further exacerbated by downsizing, is low speed pre ignition (LSPI). This thesis uses a Multiphysics approach, initially using a
validated 1D engine performance model of a GTDI engine, to define realistic
boundary conditions. A strong emphasis on validating each simulation
methodology as much as possible is maintained at each stage.
A hydrodynamic model of the ring-liner and Lagrangian CFD model are used
to investigate the impact of engine oil fluid properties on the mass of oil
transported from the crevice volume to the combustion chamber. A heat
transfer and evaporation model of a single droplet inside an engine
environment was developed for alkanes of chain lengths representing the
extremes of the chain lengths present in engine oil. It was found the droplet
generally evaporates at a crank angle which is close to the point where LSPI
is observed. The hydrocarbon study ends with a CFD constant volume
simulation to understand why engine oil like hydrocarbons ignite in rig tests
but not in an engine.
This research then proceeds to develop a single particle detergent model in
an engine environment, to initially understand why ignition occurs when a
calcium Ca based detergent is present but not in the case of a magnesium Mg
detergent. It was found from simulation that the common theory of calcium
oxide CaO resulting from thermal degradation from the previous cycle then
reacting with Carbon dioxide CO2 late in the compression stroke is unlikely.
There is a stronger case for the CaO particle causing ignition as it is present
in fresh engine oil sprayed onto the liner. As predicted by the hydrocarbon
evaporation model the oil will cover and protect the CaO particle until late in
the compression stroke when the oil will evaporate, exposing the CaO particle
to CO2
Modeling and performance evaluation of stealthy false data injection attacks on smart grid in the presence of corrupted measurements
The false data injection (FDI) attack cannot be detected by the traditional
anomaly detection techniques used in the energy system state estimators. In
this paper, we demonstrate how FDI attacks can be constructed blindly, i.e.,
without system knowledge, including topological connectivity and line reactance
information. Our analysis reveals that existing FDI attacks become detectable
(consequently unsuccessful) by the state estimator if the data contains grossly
corrupted measurements such as device malfunction and communication errors. The
proposed sparse optimization based stealthy attacks construction strategy
overcomes this limitation by separating the gross errors from the measurement
matrix. Extensive theoretical modeling and experimental evaluation show that
the proposed technique performs more stealthily (has less relative error) and
efficiently (fast enough to maintain time requirement) compared to other
methods on IEEE benchmark test systems.Comment: Keywords: Smart grid, False data injection, Blind attack, Principal
component analysis (PCA), Journal of Computer and System Sciences, Elsevier,
201
Determinants of Intra-Industry Trade between Pakistan and Selected SAARC Countries
This paper analyses country-specific and industry-specific
determinants of intra-industry trade (IIT) between Pakistan and other
SAARC countries using panel data techniques. This paper also
disentangles total IIT into horizontal and vertical IIT. The Vertical
IIT is further divided into high-quality and low quality IIT. This paper
finds that country-specific variables are more important in explaining
the IIT relative to industry-specific variables. The decomposition of
IIT shows that in the SAARC region Pakistan’s IIT is mostly comprised of
the vertical IIT. The share of horizontal IIT is comparatively less. The
paper offers specific policy recommendations for the promotion of IIT in
the SAARC region. JEL classification: F12, F14, F15 Keywords: IIT,
Horizontal IIT, Vertical II
Impact of Public Examination on Teaching of English: A Washback Perspective
Washback speaks of influence of test on teaching and learning. This paper investigates the wash back effect of Higher Secondary School Certificate (HSSC) exam on English language teaching and learning in Pakistan. The purpose of this study is to explore the causes of low level of English language proficiency at the completion of 12 years of academic education with English as a compulsory subject. To achieve this goal it examines the effect of HSSC exam on teaching methods and materials. Population of the study was all the teachers teaching English in colleges at HSSC level in Sargodha, Pakistan. A survey questionnaire consisting of ten questions was administered to the teachers of English. The questionnaire aimed at investigating the effect of HSSC on English teaching methodology and materials used by the teachers. Findings of the study affirmed that HSSC instead of supporting has negative washback effect on teaching methods and materials. Keywords: washback, HSSC exam, teaching method, teaching material
European Renaissance and Modernity: An Analytical Study of Causes and Effects
The European Renaissance stands as a pivotal period in history, marking a transition from the medieval to the modern era. This epochal shift brought forth profound changes in various aspects of European society, including art, culture, science, philosophy, and politics. Understanding the causes and effects of the Renaissance is essential for comprehending the trajectory of European civilization and its eventual emergence into modernity. European Renaissance wasn't just a cultural revival but a fundamental shift in European thought. It challenged traditional authority, fostered critical thinking, and celebrated human potential. These developments became the building blocks of modernity, shaping the scientific, political, artistic, and religious landscape of the modern world. The effects of the Renaissance reverberated far beyond the borders of Europe, influencing developments across the globe. The exploration and colonization of distant lands expanded European horizons and facilitated the exchange of goods, ideas, and cultures on a global scale. The scientific revolution, which emerged in the wake of the Renaissance, transformed humanity's understanding of the natural world, laying the groundwork for modern science and technology. This Article delves into the intricate relationship between the European Renaissance (14th-16th centuries) and the rise of modernity. It analyzes the key causes of the Renaissance and explores how these factors fundamentally reshaped European society, paving the way for the development of the modern world and presents a concise analytical study of the factors that contributed to the Renaissance and its far-reaching impacts on European society.
Keywords: Europe, Renaissance, History, Modernity, Causes, Effects, Analysi
Stress Analysis of Buried Pipeline Using Finite Element Method
تهدف هذه الدراسة إلى تحليل سلوك الجزء المدفون تحت الارض من أنابيب الصلب تحت تأثير الأحمال الناجمة عن الضغط الداخلي وتباين درجات الحرارة بسبب نقل المنتجات الهيدروكربونية. على افتراض أن خط الأنابيب مدفون في تربة رملية، وباعتماد طريقة العناصر المحددة لتنفيذ هذا التحليل باستخدام برنامج ANSYS 12.0. تم دراسة تأثير أربع متغيرات منها طول الجزء المدفون من الانبوب، خواص التربة، وعمق غطاء التربة، وحالة التقييد لنهايتي الجزء المدفون من الانبوب. حيث تبين أن زيادة طول الجزء المدفون أو زيادة قيم معاملات رد فعل التربة العمودية والمماسية للجزء المدفون من الأسباب المؤدية الى انخفاض في قيم الازاحات الطولية، والإجهاد، والانفعال. كما أن عمق غطاء التربة على الجزء المدفون من الانبوب ليس له أي تأثير على النزوح الطولي، ولكن الاجهادات والانفعالات زادت عند زيادة عمق غطاء التربة. من دراسة تأثير حالة التقييد لطرفي الجزء المدفون، وجدت أن الحد الأقصى للازاحات الطولية لم تتأثر، ولكن قيم الاجهادات والانفعالات الطولية زادت بمقادير صغيرة.This study aims to analyze the behavior of underground part of steel pipelines under the effect of loads caused by internal pressure and temperature variation due to transportation of hydrocarbon products. The pipeline assumed to be buried in a sandy soil. The finite element method is used to carry out this analysis using ANSYS 12.0 program. Four parameters are studied including length of the buried part of the pipeline, soil properties, depth of soil cover, and ends condition of the buried part of the pipeline. It is found that increasing the length of the buried part of the pipeline or increasing values of the normal and tangential modulus of subgrade reactions for the surrounding soil causes decreasing in the values of longitudinal displacement, stress, and strain. Soil cover depth over buried pipeline has no effect on the longitudinal displacement, but the stresses and strain increased when the soil cover depth increases. From studying the effect of boundary conditions of the two ends of steel buried pipeline, it is found that longitudinal maximum displacement did not affected, but the longitudinal stresses and strains increase with small rate values
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