134 research outputs found
WIND POWER PROBABILISTIC PREDICTION AND UNCERTAINTY MODELING FOR OPERATION OF LARGE-SCALE POWER SYSTEMS
Over the last decade, large scale renewable energy generation has been integrated into power systems. Wind power generation is known as a widely-used and interesting kind of renewable energy generation around the world. However, the high uncertainty of wind power generation leads to some unavoidable error in wind power prediction process; consequently, it makes the optimal operation and control of power systems very challenging. Since wind power prediction error cannot be entirely removed, providing accurate models for wind power uncertainty can assist power system operators in mitigating its negative effects on decision making conditions. There are efficient ways to show the wind power uncertainty, (i) accurate wind power prediction error probability distribution modeling in the form of probability density functions and (ii) construction of reliable and sharp prediction intervals. Construction of accurate probability density functions and high-quality prediction intervals are difficult because wind power time series is non-stationary. In addition, incorporation of probability density functions and prediction intervals in power systems’ decision-making problems are challenging. In this thesis, the goal is to propose comprehensive frameworks for wind power uncertainty modeling in the form of both probability density functions and prediction intervals and incorporation of each model in power systems’ decision-making problems such as look-ahead economic dispatch.
To accurately quantify the uncertainty of wind power generation, different approaches are studied, and a comprehensive framework is then proposed to construct the probability density functions using a mixture of beta kernels. The framework outperforms benchmarks because it can validly capture the actual features of wind power probability density function such as main mass, boundaries, high skewness, and fat tails from the wind power sample moments. Also, using the proposed framework, a generic convex model is proposed for chance-constrained look-ahead economic dispatch problems. It allows power system operators to use piecewise linearization techniques to convert the problem to a mixed-integer linear programming problem. Numerical simulations using IEEE 118-bus test system show that compared with widely used sequential linear programming approaches, the proposed mixed-integer linear programming model leads to less system’s total cost.
A framework based on the concept of bandwidth selection for a new and flexible kernel density estimator is proposed for construction of prediction intervals. Unlike previous related works, the proposed framework uses neither a cost function-based optimization problem nor point prediction results; rather, a diffusion-based kernel density estimator is utilized to achieve high-quality prediction intervals for non-stationary wind power time series. The proposed prediction interval construction framework is also founded based on a parallel computing procedure to promote the computational efficiency for practical applications in power systems. Simulation results demonstrate the high performance of the proposed framework compared to well-known conventional benchmarks such as bootstrap extreme learning machine, lower upper bound estimation, quantile regression, auto-regressive integrated moving average, and linear programming-based quantile regression.
Finally, a new adjustable robust optimization approach is used to incorporate the constructed prediction intervals with the proposed fuzzy and adaptive diffusion estimator-based prediction interval construction framework. However, to accurately model the correlation and dependence structure of wind farms, especially in high dimensional cases, C-Vine copula models are used for prediction interval construction. The simulation results show that uncertainty modeling using C-Vine copula can lead the system operators to get more realistic sense about the level of overall uncertainty in the system, and consequently more conservative results for energy and reserve scheduling are obtained
A Multi-Objective Economic Load Dispatch Considering Accessibility of Wind Power with Here-And-Now Approach
The major problem of wind turbines is the great variability of wind power production. The dynamic change of the wind speed returns the quantity of the power injected to networks. Therefore, wind–thermal generation scheduling problem plays a key role to implement clean power producers in a competitive environment. In deregulated power systems, the scheduling problem has various objectives than in a traditional system which should be considered in economic scheduling. In this paper, a Multi-Objective Economic Load Dispatch (MOELD) model is developed for the system consisting of both thermal generators and wind turbines. Using two optimization methods, Sequential Quadratic Programming (SQP) and Particle Swarm Optimization (PSO), the system is optimally scheduled. The objective functions are total emission and total profit of units. The probability of stochastic wind power is included in the model as a constraint. This strategy, referred to as the Here-and-Now (HN) approach, avoids the probabilistic infeasibility appearing in conventional models. Based on the utilized model, the effect of stochastic wind speed on the objective functions can be readily assessed. Also a Total Index (TI) is presented to evaluate the simulation results. Also, the results show preference of PSO method to combine with HN approach
Context effects in personnel selection
Das Antwortverhalten in psychologisch-diagnostischen Verfahren wird nicht ausschließlich durch die entsprechenden Eigenschaften oder Fähigkeiten bestimmt, sondern von zahlreichen anderen (personen-, verfahrens- und situationsspezifischen) Variablen beeinflusst. Diese resultieren in so genannte Kontexteffekte, die die Messung mitunter negativ beeinflussen können. Absichtliches Verfälschen („impression management“, „faking good“, sozial erwünschtes Antwortverhalten) in Persönlichkeitsfragebogen und Effekte unterschiedlicher Testreihenfolgen können beide als derartige Kontexteffekte bezeichnet werden. Die vorliegende Arbeit setzt sich aus drei wissenschaftlichen Artikeln zusammen, die den Einfluss unterschiedlicher Strategien (unterschiedliche Antwortformate, Instruktionen, limitierte Bearbeitungszeit und Fragebogenlänge) auf sozial erwünschtes Antwortverhalten, sowie den Effekt unterschiedlicher Testreihenfolgen auf die Testleistung in Objektiven Persönlichkeitstests und kognitiven Leistungstests an Bewerbern untersuchen. Die Ergebnisse der Studien werden ergänzt durch zwei weitere wissenschaftliche Artikel, die wiederum die Effekte unterschiedlicher Antwortformate auf sozial erwünschtes Antwortverhalten und die Effekte unterschiedlicher Testreihenfolgen auf die Testleistung untersuchen, jedoch an anderen Stichproben und mit teilweise anderen Verfahren. Die Ergebnisse unterstützen die Hypothese, dass Antwortskalen mit einer höheren Anzahl von Antwortalternativen (Analogskalen oder 6-kategorielle Rating-Skalen), Instruktionen mit der Warnung, dass Verfälscher entlarvt werden können, und Items, die am Ende eines Fragebogens platziert sind, zu weniger sozial erwünschtem Antwortverhalten führen, als Antwortskalen mit nur zwei Antwortalternativen (dichotome Antwortformate oder 2-kategorielle Rating-Skalen), Instruktionen ohne Warnung und Items, die am Beginn eines Fragebogens platziert sind. Diese Strategien scheinen für Testteilnehmer die Adaption ihrer Antworten an ein Faking-Schema zu erschweren (Holden & Hibbs, 1995; Holden, Kroner, Fekken, & Popham, 1992) oder deren Motivation zu verfälschen zu beeinflussen (Rothstein & Goffin, 2006). Eine limitiere Bearbeitungszeit führte ebenfalls zu einer Reduktion sozial erwünschten Antwortverhaltens, allerdings nur in Kombination mit einer Analogskala oder einer Warninstruktion. Die Effekte der einzelnen Strategien waren entweder innerhalb der einzelnen Studien oder über mehrere Studien hinweg nicht konsistent, was zu der Annahme führt, dass es eine Interaktion zwischen personenspezifischen Variablen und Skaleninhalten oder Itemformulierungen gibt. Weiters gibt es einen Einfluss unterschiedlicher Testreihenfolgen auf die Testleistung in Objektiven Persönlichkeitstests, nicht jedoch auf jene in kognitiven Leistungstests. Testteilnehmer, die zuerst an kognitiven Leistungstests und danach an Objektiven Persönlichkeitstest arbeiteten, zeigten eine höhere Entscheidungsfreude und eine geringere Frustrationstoleranz in den Objektiven Persönlichkeitstests, als Testteilnehmer, die zuerst an Objektiven Persönlichkeitstest arbeiteten. Wiederum waren die Ergebnisse über mehrere Studien hinweg nicht konsistent. Insgesamt unterstützen die Ergebnisse die Theorie, dass individuelle Unterschiede das Verfälschen beeinflussen (Mueller-Hanson, Heggestad, & Thornton, 2006; Viswesvaran, & Ones, 1999) und die Theorie, dass Kontexteffekte von Unterschieden in der Motivation und in kognitiven Fähigkeiten von Testteilnehmern abhängen (Schwarz, Hippler, & Noelle-Neumann, 1992).Responses on psychological tests or questionnaires are not always determined by mapping the trait directly on a response scale as they can also be influenced by numerous other variables (person, test, and situation related) resulting in context effects, which might sometimes harm the measurement. Intentional response distortion (impression management, faking good, socially desirable response behaviour) in personality questionnaires and the effects of different test orders can both be described as such contexts effects. The current thesis consists of three scientific articles (papers) and an additional study, which investigate the effects of different strategies (such as different response formats, instructions, limited response time, and questionnaire length) to decrease socially desirable response behaviour, as well as the effects of different test orders on the test performance in objective personality tests and cognitive ability tests, by examining applicants. Their findings are completed by two further scientific articles (papers), which investigate the effects of different response formats on impression management and the effects of different test orders on test performance once again, however with different samples and partially different questionnaires and tests. Results provide evidence for the hypothesis that response scales with a higher number of response alternatives (analogue scales or 6-point rating scales), instructions with warnings (that fakers can be detected), and items positioned at the end of a questionnaire lead to less socially desirable responses than response scales with only two response alternatives (dichotomous response formats or 2-point rating scales), instructions without a warning, and items positioned at the beginning of a questionnaire. These strategies seem to make it more difficult for test-takers to fit their responses to a faking schema (Holden & Hibbs, 1995; Holden, Kroner, Fekken, & Popham, 1992) or to influence test-takers’ motivation to fake (Rothstein & Goffin, 2006). A limited response time was shown to lead to less socially desirable responses as well, but only in combination with an analogue scale or a warning instruction. The effects of the different strategies were either not consistent within or across the different studies, which leads to the assumption that there is an interaction between person related variables and the content of the questionnaire scales or item wording. Moreover, different test orders influenced the test performance in objective personality tests but not in cognitive ability tests. Test-takers, who worked on cognitive ability tests first and on objective personality tests second, were shown to be more decisive and to have a lower tolerance to frustration in the objective personality tests than test-takers, who had worked on objective personality tests first. Again, results were not consistent across the different studies. Altogether, evidence is provided for the theory that faking is a variable of individual differences (Mueller-Hanson, Heggestad, & Thornton, 2006; Viswesvaran, & Ones, 1999), and for the theory that context effects depend on differences in test-takers’ motivation and cognitive ability (Schwarz, Hippler, & Noelle-Neumann, 1992)
Additive and Digital Fabrication of 3D Interconnects in MEMS Packaging Using Printing Technologies
With the introduction of electrically functional inks and continuous development of printing equipment, the application of printed electronics in the fabrication of electronic circuits, structures and devices has been steadily growing over recent years. Among printed electronic methods, digital printing has the potential to be integrated within silicon-based microelectronics such as microelectromechanical devices (MEMS). Currently, MEMS manufacturing and packaging involves subtractive processes like lithography which are time consuming and need extensive processing conditions and expensive facilities.This thesis investigates the feasibility of using printing technologies for the selected parts of the MEMS packaging. Additive, maskless and non-contact printing technologies are digitally controlled by computer and have the potential to reduce turnaround time compared with lithographic processes. These methods could be used for the substrate with any morphology and composition; and also enable the deposition of functional inks with high level of precision on designated places defined by the graphics or codes prepared by the computer software. In summary, printing technologies provide the possibility to reduce harmful waste, consumption of the material and chemicals, process steps, and process time compared to subtractive processes.The focus of this research has been on the fabrication of the 3D interconnects in parts of the MEMS packaging. The fabrication methods used in this work are piezo drop on demand (DOD) inkjet printing, super-fine inkjet technology (SIJ) and aerosol jet printing (AJP). Also, a combination of metal nanoparticle and dielectric inks have been used for the experiments reported in this thesis. The reported results show promising potential for additive methods to be used in electronics manufacturing in coming years with more developments and refinements in inkjettable functional materials and printing devices. In this thesis inkjet printing is utilized to fabricate 3D interconnects by the partial metallization of through silicon vias (TSVs). The via metallization could result in low resistance vias suitable for some MEMS applications. Complete filling of high density vias with diameters of less than 30 µm using super-fine inkjet technology is also demonstrated. As well, aerosol jet printing is successfully used to make a conductive bridge with low resistance between the device layer and handle wafer in silicon on insulator (SOI) MEMS. In addition, inkjet printing technologies are used to fill the TSVs to planarize wafer surface which enables placement of solder balls on top of the TSVs and increasing the I/O density of 3D TSV interposers by four times without using the next generation of TSV nodes. Moreover, successful fabrication of silver micropillars/bumps with inkjet printing is demonstrated for use in flip-chip fabrication methods instead of using stud bumps fabricated by wire bonding. The results indicate that the bare dies with the printed bumps can increase the contact reliability of flip-chip bonded samples
Development and validation of a metacognitive-cognitive-behavioral model for explaining trichotillomania
Background & Aims: Trichotillomania (TTM) is an unknown disorder and resistant to treatment. The purpose of this study was to develop and validate the new metacognitive-cognitive-behavioral model for trichotillomania. Methods: The present study was a description and correlation study. In this study, 635 participants (304 male and 331 female) were selected. The participants completed the Massachusetts general hospital hair pulling scale (MGH-HPS), dysfunctional attitude scale (DAS), cognitive distortion scale (CDS), automatic thought questionnaire (ATQ), metacognition questionnaire (MCQ), and the obsessive-compulsive behavior scale (OCBS). For reliability assessment of the factor structure of the metacognitive-cognitive-behavioral model, the structural equation modeling analysis was used by AMOS software. Results: The results of the structural equation modeling supported a metacognitive-cognitive-behavioral model for trichotillomania. Moreover, the results showed that the model had the best fit to the data and was closely related to the theoretical assumptions. Conclusion: The model presented in this study illustrates a multidimensional approach that focuses on the metacognitive, cognitive, and behavioral dimensions; hence, the model presented in this study is a new explanatory model. This model may prompt future research into trichotillomania and facilitate clinical treatment and case formulation. © 2014, Kerman University of Medical Sciences. All rights reserved
Effect of organic fertilizers on nutrients content and essential oil composition of savory (Satureja hortensis L.)
Application of organic fertilizers in the production of plants is aimed to eliminate or substantially reduce the use of chemical inputs and improve the growth and quality of plants. For instance, in present study, the effect of vermicompost and spent mushroom compost application on nutritional status and essential oil components of summer Savory (Saturejahortensis L.) was investigated. This experiment was conducted in the research greenhouse of Faculty of Agriculture at Mohaghegh Ardabili University using a layout of completely randomized design with five replications on Savory in 2014. Experimental treatments included different substrates that contained vermicompost, washed and unwashed spent mushroom compost in five levels (10, 20, 30, 40 and 50 Percent v/v). After flowering, the plants were harvested and parameters such as leaf area, leaf and plant dry weight, chlorophyll index of leaf and N, P, K, and Ca content and essential oil component of plants were measured. The results showed that the effect of organic substrates on macronutrient content and savory’s growth parameters was significant. The highest Nitrogen content (6.3%) and Phosphorus (0.98%) in savory shoot was obtained in a substrate supplemented with 40% vermicompost. Plants grown in the media containing 30% of vermicompost and 50% of washed spent mushroom compost (SMC) have higher potassium (3.19%) and calcium (2.48%) content, respectively. The lowest nitrogen, phosphorus and potassium content in the aerial part was obtained in the control treatment. Moreover, application of organic fertilizers significantly affected on savory’s essential oil percentage and compounds composition. The highest and lowest essential oil contents were obtained in plants in substrates containing 30 % of vermicompost and unwashed spent mushroom compost respectively. The main components of essential oil were carvacrol and gamma-trepenine. The highest level of carvacrol (62.10) and gamma-trepenine (32.05) were obtained in plants in substrates containing 40 and 20% of washed spent mushroom respectively
Evaluation of Carbon Sequestration and Global Warming Potential of Wheat in Khorasan-Razavi province
In order to determine soil characteristics and above-ground and below-ground carbon sequestration potential of wheat, a systematic random sampling method was employed to select 5 samples from 50 fields situated in Khorasan-Razavi Province, Iran during 2015. The experimental design was a completely randomized design with three replications. The ash method was used to determine the carbon sequestration conversion coefficients in spikes, stems, leaves and roots. Then, greenhouse gases (such as CO2, N2O and CH4) emission were calculated using emission coefficients. The average organic carbon, total nitrogen, available phosphorus, available potassium, soil bulk density, pH and electrical conductivity were found to be 0.98%, 0.02%, 27.07 ppm, 341.32 ppm, 1.37 g.cm-3, 7.81 and 1.42 dS.m-1, respectively. The maximum (52.0%) and minimum (31.99%) conversion coefficients were related to spikes (seeds included) and roots, respectively. In addition, the total carbon sequestration was 8.25 t.ha-1 so that the maximum (4.28 t.ha-1) and minimum (0.35 t.ha-1) values were found in stems and roots, respectively. The total global warming potential (GWP) of wheat was recorded as 2377.86 kg CO2 –equiv. per ton of seed. The first contributing factor was nitrogen fertilizers, accounting for 1331.30 kg CO2 –equiv. per ton of seed
EVALUATION OF CLIMATIC AGRICULTURAL POTENTIALS OF FARS PROVINCE USING PAPADAKIS TECHNIQUE
ABSTRACT Accurate and simultaneous recognition of climatic facts and ecological phenomena requires use of a technique which is free from ambiguities and generalized concepts and is based on robust fundamentals. With more than 440 subcategories, Papadakis climatic classification which emphasizes on the role of ecological factors has the aforementioned advantage in spite of its particular complexities. In the present paper, after a concise introduction of Papadakis method, meteorological data of 8 selected stations in Fars Province are processed and analyzed using EXCEL software based on the afore mentioned method. The analysis results will be illustrated in maps prepared in GIS software by means of ARCMAP software. The criteria of this method include: winter coldness and summer warmness, duration of frostless season, potential evapotranspiration, and water balance and its seasonal distribution. The research achievements are indicative of the fact that all stations are classified in cotton group in terms of summer temperature status. The stations under study are more diverse with respect to the winter temperature conditions such that two stations are classified in the oat or Avena sativa group (cooler), five stations in warmer oat group, one station in citrus group and one station in class of wheat. In terms of temperature regime, two stations are classified in warm continental group and 6 stations are regarded as warm subtropical climates. Concerning moisture regime, there are two stations in arid Mediterranean and 6 stations in semi-arid Mediterranean classes. The final result implies that all stations are classified in one group and 3 types. This is reflective of the agro-climatic diversity of Fars Province as well as high competence of Papadakis method in illustration of details and climatic subzones
The relationship between the severity and specific dimensions of OCD in Iranian clinical sample
Background: There have been a few studies that examined the association between insight and the clinical symptoms of obsessive-compulsive disorder (OCD) among the Middle Eastern population. The current study aimed to find a relationship between insight, general score and the specific dimensions of OCD among Iranian clinical sample. Method: The cross-sectional research method was conducted on 108 OCD patients from 18 to 61 years old. Participants were interviewed with a semi-structured interview based on DSM-V, and those who were diagnosed with other psychiatric disorders were excluded. Also, participants filled out some self-report scales including Obsessive-Compulsive Inventory-Revised, Overall Anxiety Severity and Impairment Scale and Beck Depression-II Inventory. Result: The results showed that poor insight has a relationship with OCD symptoms except for hoarding. Moreover, anxiety was significantly correlated with the severity of OCD
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