Power factor and your electrical utility bill in Egypt

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2003 IEEEBeside being a good neighbor and not causing harmonic voltage for others that are connected to your electrical distribution circuit, complying with the legal requirements of IEEE standards 519, and maintaining safe and economical operating environments for electrical equipment within your physical load, there is another very good reason to maintain a good power factor: saving money on your electrical utility bill. Utilities often encourage consumers to maintain a high PF by applying tariff clauses, which penalize consumers for low PF. This letter discusses the topic

Computationally efficient quantum-mechanical technique to calculate direct tunnelling gate leakage current in metal-oxide-semiconductor structures

We propose a computationally efficient, accurate and numerically stable quantum- mechanical technique to calculate the direct tunneling (DT)gate current in metal-oxide-semiconductor (MOS) structures. Knowledge of the imaginary part G of the complex eigenenergy of the quasi-bound inversion layer states is required to estimate the lifetimes of these states. Exploiting the numerically obtained exponential dependence of G on the thickness of the gate-dielectric layer even in the sub-1-nm-thickness regime, we have simplified the determination of G in devices where it is too small to be calculated directly. It is also shown that the MOS electrostatics, calculated self-consistently with open boundary conditions, is independent of the dielectric layer tickness provided that the other parameters remain unchanged. Utilizing these findings, a computationally efficient and numerically stable method is developed for calculating the tunneling current–gate voltage characteristics. The validity of the proposed model is demonstrated by comparing simulation results with experimental data. Sample calculations for MOS transistors with high-K gate-dielectric materials are also presented. This model is particularly suitable for DT current calculation in devices with thicker gate dielectrics and in device or process characterization from the tunneling current measurement

The most economical power factor correction according to tariff structures in Egypt

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2005 IEEEA method of applying power-factor (PF) correction capacitors is discussed based on net savings maximization according to Egyptian's Tariff. Test results from examples taken from existing publications are presented. The purpose of this application technique is to utilize existing electrical distribution equipment in the installation of very large values of PF correction capacitors. It is concluded that LC compensators can be installed, thus providing maximum benefits from penalty elimination, system losses reduction, release of system transformer capacity, and minimum switching transients. Paybacks of less than one year can be expected

Practical considerations regarding power factor for nonlinear loads

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThe choice of LC compensator may be constrained by the availability of manufacturers units. To account for this, the capacitor values are chosen from among standard values and for each value the transmission losses is minimized, or power factor is maximized, or transmission efficiency is maximized. The global minimum or maximum is obtained by scanning all local minims or maxims. The performance of the obtained compensator is discussed by means of numerical examples

A Review of Semantic Search Methods to Retrieve Information from the Qur’an Corpus

The Holy Qur’an is the most important resource for the Islamic sciences and the Arabic language (Iqbal et al., 2013). Muslims believe that the Qur’an is a revelation from Allah that was given 1,356 years ago. The Qur’an contains about 80,000 words divided into 114 chapters (Atwell et al., 2011). A chapter consists of a varying number of verses. This holy book contains information on diverse topics, such as life and the history of humanity and scientific knowledge (Alrehaili and Atwell, 2014). Corpus linguistics methods can be applied to study the lexical patterns in the Qur’an; for example, the Qur’an is one of the corpora available on the SketchEngine website. Qur’an researchers may want to go beyond word patterns to search for specific concepts and information. As a result, many Qur’anic search applications have been built to facilitate the retrieval of information from the Qur’an. Examples of these web applications are Qurany (Abbas, 2009), Qur’an Explorer (Explorer, 2005), Tanzil (Zarrabi-Zadeh, 2007), Qur’anic Arabic corpus (Dukes, 2013), and Quran.com. The techniques used to retrieve information from the Qur’an can be classified into two types: semantic-based and keyword-based. Semantic-based search techniques are concept-based which retrieves results by matching the contextual meaning of terms as they appear in a user’s query, whereas the keyword-based search technique returns results according to the letters in the word(s) of a query (Sudeepthi et al., 2012). The majority of Qur’anic search tools employ the keyword search technique. The existing Qur’anic semantic search techniques include the ontology-based technique (concepts) (Yauri et al., 2013), the synonyms-set technique (Shoaib et al., 2009), and the cross language information retrieval (CLIR) technique (Yunus et al., 2010). The ontology-based technique searches for the concept(s) matching a user’s query and then returns the verses related to these concept(s). The synonyms-set method produces all synonyms of the query word using WordNet and then returns all Qur’anic verses that contain words matching any synonyms of the query word. Cross language information retrieval (CLIR) translates the words of an input query into another language and then retrieves verses that contain words matching the translated words. On the other hand, keyword-based techniques include keyword matching, the morphologically-based technique (Al Gharaibeh et al., 2011), and use of a Chabot (Abu Shawar and Atwell, 2004). The keyword matching method returns verses that contain any of the query words. The morphologically-based technique uses stems of query words to search in the Qur’an corpus. In other words, this technique generates all other forms of the query words and then finds all Qur’anic verses matching those word forms. The Chabot selects the most important words such as nouns or verbs from a user query and then returns the Qur’anic verses that contain any words matching the selected words. There are several deficiencies with the Qur’anic verses (Aya’at) retrieved for a query using the existing keyword search technique. These problems include the following: some irrelevant verses are retrieved, some relevant verses are not retrieved, or the sequence of retrieved verses is not in the right order (Shoaib et al., 2009). Misunderstanding the exact meaning of input words forming a query and neglecting some theories of information retrieval contribute significantly to limitations in the keyword-based technique (Raza et al.). Additionally, Qur’anic keyword search tools use limited Islamic resources related to the Qur’an. This affects the accuracy of the retrieved results. Moreover, current Qur’anic semantic search techniques have limitations in retrieved results. The main causes of these limitations include the following: semantic search tools use one source of Qur’anic ontology that does not cover all concepts in the Holy Qur’an, and Qur’anic ontologies are not aligned to each other, leading to inaccurate and uncomprehensive resources for Qur’anic ontology. To overcome the limitations in both semantic and keyword search techniques, we designed a framework for a new semantic search tool called the Qur’anic Semantic Search Tool (QSST). This search tool aims to employ both text-based and semantic search techniques. QSST aligns the existing Quranic ontologies to reduce the ambiguity in the search results. QSST can be divided into four components: a natural language analyser (NLA), a semantic search model (SSM), a keywords search model (KSM), and a scoring and ranking model (SRM). NLA tokenizes a user’s query and then applies different natural language processing techniques to the tokenized query. These techniques are the following: spelling correction, stop word removal, stemming, and part of speech tagging (POS). After that, the NLA uses WordNet to generate synonyms for the reformatted query words and sends these synonyms to the SSM and the KSM. The SSM searches in the Qur’anic Ontology database to find the related concepts of the normalised query and then returns results. At the same time, KSM retrieves results based on words matching the input words. SRM refines the results retrieved from both KSM and SSM by eliminating the redundant verses. Next, SRM ranks and scores the refined results. Finally, SRM presents the results to the user. References Abbas, N. H. 2009. Quran 'search for a concept' tool and website. MRes thesis, University of Leeds. Abu Shawar, B. and Atwell, E. 2004. An Arabic chatbot giving answers from the Qur'an. Proceedings of TALN. 4(2), pp.197-202. Al Gharaibeh, A. et al. 2011. The usage of formal methods in Quran search system. In: Proceedings of international conference on information and communication systems, Ibrid, Jordan. pp.22-24. Alrehaili, S. M. and Atwell, E. 2014. Computational ontologies for semantic tagging of the Quran: A survey of past approaches. In: LREC 2014 Proceedings. Atwell, E. et al. 2011. An artificial intelligence approach to Arabic and Islamic content on the internet. In: Proceedings of NITS 3rd National Information Technology Symposium. Dukes, K. 2013. Statistical parsing by machine learning from a classical Arabic treebank. PhD thesis. Explorer, Q. 2005. Quran Explorer [Online]. [Accessed 26 October 2014]. Available from: http://www.quranexplorer.com/Search/Default.aspx Iqbal, R. et al. 2013. An experience of developing Quran ontology with contextual information support. Multicultural Education & Technology Journal. 7, pp.333-343. Raza, S.A. et al. An essential framework for concept based evolutionary Quranic search engine (CEQSE). Shoaib, M. et al. 2009. Relational WordNet model for semantic search in Holy Quran. Emerging Technologies, 2009. ICET 2009. International Conference on, 2009. IEEE, 29-34. Sudeepthi, G. et al. 2012. A survey on semantic web search engine. International Journal of Computer Science, 9. Yauri, A. R. et al. 2013. Quranic verse extraction based on concepts using OWL-DL ontology. Research Journal of Applied Sciences Engineering and Technology. 6, pp.4492-4498. Yunus, M. et al. 2010. Semantic query for Quran documents results. Open Systems (ICOS), 2010 IEEE Conference on, 2010. IEEE, 1-5. Zarrabi-Zadeh, H. 2007. Tanzil [Online]. [Accessed 26 October 2014]. Available from: http://tanzil.net

Qur’anic search tool based on ontology of concepts

The Holy Quran is the most important resource for the Islamic sciences and Arabic Language (Iqbal et al., 2013). Additionally, this holy book contains knowledge on diverse topics such as life and history of humanity, and scientific knowledge (Alrehaili and Atwell, 2014). As a consequence, many Qur’anic search applications have been built to facilitate the retrieval of knowledge from the Quran. Examples of these web applications are Qurany (Abbas, 2009), Quran Explorer (Explorer, 2005), Tanzil (Zarrabi-Zadeh, 2007), and Qur’anic Arabic corpus (Dukes, 2013). The techniques used to retrieve information from Qur’an can be classified as semantic-based and text-based. The existing semantic search techniques are: ontology-based (concepts) (Yauri et al., 2013), Synonyms-set (Shoaib et al., 2009), and Cross Language Information retrieval (CLIR) (Yunus et al., 2010). On the other hand, text-based techniques are Keyword matching, and Morphological-based (Al Gharaibeh et al., 2011). The majority of Qur’anic search tools employ a keyword search technique while minority of tools use a semantic technique. There are several deficiencies with the verses (Aya’at) retrieved for a query using existing search tools. These problems are: some irrelevant verses are retrieved, some relevant verses are not retrieved, or the sequence of retrieved verses is not in the right order (Shoaib et al., 2009) . The significant reasons for unsatisfactory searching results are: absence of an accurate and comprehensive resource for Islamic ontology (Alrehaili and Atwell, 2014), and neglecting some theories of information retrieval . This project aims to construct a useful Qur’anic search tool by employing both text-based techniques, and semantic search techniques. The research will answer two questions: Is it possible to implement a useful search tool based on Qur’anic ontology, and Qur’anic datasets? And How to assess the efficiency and accuracy of an existing Qur’anic ontology? Furthermore, the main project objectives are to understand the problem by evaluating existing Qur’anic semantic search, assess the current Islamic ontologies and find out how these ontologies can be developed, and find the latest search techniques to employ in a Qur’anic search engine

LC compensators for power factor correction of nonlinear loads

This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEA method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor, and maximizes the efficiency. The performance of the obtained compensator is discussed by means of numerical examples

Assessment of risky sexual practices with respect to HIV among South African young adults.

South Africa is one of the countries hardest hit by the HIV/AIDS pandemic in the world. With ever increasing prevalence rates of HIV infection, those who fall within the 14 - 29 years age group remain the population most at risk for HIV/AIDS. In spite of educational and awareness campaigns, the rates of new infections continues to rise among this age group, suggesting that these campaigns alone may not be as effective as was initially envisioned. Research exploring factors that may mediate or moderate the relation between HIV awareness and knowledge and behaviour has proliferated in recent years. The present study investigates whether the Health Belief Model constructs predict and perhaps moderate the relation between HIV knowledge / awareness and Risky sexual practices. The study further explores the role of Sexual orientation and attempts to reflect on the question of whether education and awareness programmes should be tailored for specific sub-populations. The sample consisted of 200 second year university students from the Humanities Faculty at the University of the Witwatersrand. Participants completed a survey of questions that consisted of Demographic information, Sexual Practices Questionnaire, HIV Knowledge Questionnaire, an AIDS Health Belief scale and Generalized Self efficacy Scale. Results yielded a significant relation between Perceived benefit (Health Belief Model construct) and HIV knowledge. No other significant differences were identified between the other variables

Drain current multiplication in thin pillar vertical MOSFETs due to depletion isolation and charge coupling

Drain current multiplication in vertical MOSFETs due to body isolation by the drain depletion region and gate–gate charge coupling is investigated at pillar thicknesses in the range of 200–10 nm. For pillar thickness >120 nm depletion isolation does not occur and hence the body contact is found to be completely effective with no multiplication in drain current, whereas for pillar thicknesses <60 nm depletion isolation occurs for all drain biases and hence the body contact is ineffective. For intermediate pillar thicknesses of 60–120 nm, even though depletion isolation is apparent, the body contact is still effective in improving floating body effects and breakdown. At these intermediate pillar thicknesses, a kink is also observed in the output characteristics due to partial depletion isolation. The charging kink and the breakdown behavior are characterized as a function of pillar thickness, and a transition in the transistor behavior is seen at a pillar thickness of 60 nm. For pillar thickness greater than 60 nm, the voltage at which body charging occurs decreases (and the normalized breakdown current increases) with decreasing pillar thickness, whereas for pillar thickness less than 60 nm, the opposite trend is seen. The relative contributions to the drain current of depletion isolation and the inherent gate–gate charge coupling are quantified. For pillar thickness between 120 and 80 nm, the rise in the drain current is found to be mainly due to depletion isolation, whereas for pillar thicknesses <60 nm, the increase in the drain current is found to be governed by the inherent gate–gate charge coupling