Modelling of reduced GB transmission system in PSCAD/EMTDC

Energy and environmental issues are two of the greatest challenges facing the world today. In response to energy needs and environmental concerns, renewable energy technologies are now considered the future technologies of choice. Renewable energy is produced from natural sources that are clean and free; however, it is widely accepted that renewable energy is not a solution without challenges. An example of this can be seen in the UK, where there is much interest amongst generation developers in the construction of new large scale onshore and offshore wind farms, especially in Scotland. The stability of electric power systems is also an important issue. It is important to have full knowledge of the system and to be able to predict the behaviour under different situations is an important objective. As a result, several industrial grade power system simulator tools have been developed in order to estimate the behaviour of the electric power system under certain conditions. This paper presents a reduced Great Britain (GB) system model for stability analysis using PSCAD/EMTDC. The reduced model is based upon a future GB transmission system model and, hence, contains different types and mix of generation, HVDC transmission lines and additional interconnection. The model is based on the reduced DIgSILENT PowerFactory model developed by National Grid

Feedback Revisited: Definitional, Structural, and Functional Issues

This article provides a more fundamental overview that addresses the following provisions associated with feedback in an integrative way. First, several linguistic and definitional issues relating to the term ‘feedback’ are discussed. Second, the article draws attention to the challenges and implications associated with online feedback being increasingly used primarily during the contemporary shift toward online learning. Then, the article spots light on the importance of feedback at multiple levels, followed by a discussion of feedback purposes and potential benefits on student learning and progress, both in the short and long term. This article seeks to contribute to the literature on formative feedback by providing a more profound understanding of the conceptualizations of feedback by incorporating definitional, structural, and functional issues about feedback both as a construct and a practice

Gain properties of dye-doped polymer thin films

Hybrid pumping appears as a promising compromise in order to reach the much coveted goal of an electrically pumped organic laser. In such configuration the organic material is optically pumped by an electrically pumped inorganic device on chip. This engineering solution requires therefore an optimization of the organic gain medium under optical pumping. Here, we report a detailed study of the gain features of dye-doped polymer thin films. In particular we introduce the gain efficiency $K$, in order to facilitate comparison between different materials and experimental conditions. The gain efficiency was measured with various setups (pump-probe amplification, variable stripe length method, laser thresholds) in order to study several factors which modify the actual gain of a layer, namely the confinement factor, the pump polarization, the molecular anisotropy, and the re-absorption. For instance, for a 600 nm thick 5 wt\% DCM doped PMMA layer, the different experimental approaches give a consistent value $K\simeq$ 80 cm.MW$^{-1}$. On the contrary, the usual model predicting the gain from the characteristics of the material leads to an overestimation by two orders of magnitude, which raises a serious problem in the design of actual devices. In this context, we demonstrate the feasibility to infer the gain efficiency from the laser threshold of well-calibrated devices. Besides, temporal measurements at the picosecond scale were carried out to support the analysis.Comment: 15 pages, 17 figure

A new comprehensive framework for ranking accepted orders and supplier selection in make-to-order environments

This paper presents a new decision making framework for supplier selection in a make-to-order-system (MTO) while establishing an information loop between "sale" and "purchasing" functions which play important roles in successful satisfying of customers. The order entry stage outputs, including accepted orders' requirements and their priorities are reflected into the supplier selection phase; and in return, the outputs of the supplier selection model are fed back into the sale department to revise the orders attributes according to the system's supplying capabilities. A ranking procedure using Fuzzy data-envelopment-analysis (DEA) and multi attribute utility model (Le. similarity to ideal solution TOPSIS) is applied to determine the relative ranking of accepted orders; in the next phase a goal programming supplier selection model focusing on three criteria of time, cost and quality is run to determine the best ability of the system in supplying required components and materials of the accepted orders

Identifying big data’s opportunities, challenges, and implications in finance

One of the latest innovations in business and technology is the use of big data, as daily data is generated by billions of events. The big data issue is now considered in the accountants and finance professionals’ field as one of the most important sources for the analysis of financial products and services. This study is very innovative, aiming our research to identify the opportunities, challenges, and implications of big data in the finance area. It is our purpose to find competitive advantages in extents on which big data brings visible benefits, also pointing out the challenges that a company may face in this field, as are the cases of customers' data security or customer satisfaction processes. The identification of this kind of dynamics allows us to conclude about the big advantages of big data on these analyses and big data’s deep impact on finance. Very particularly, the big data is now commonly used by financial institutions and banks for analytical purposes in financial markets contexts. We have conducted an exploratory survey of the existing literature to highlight such connections. In the last part of our study, we also propose some directions for future research.info:eu-repo/semantics/publishedVersio

Synthesis, structural and antibacterial study of new silver complex with 3-acetyl-2H chromene-2-one

A new silver complex [Ag(C11H8O3)2]NO3 was synthesized by the reaction of silver nitrateand coumarin based ligand (3-acetyl-2H-chromene-2-one) through solution method. The product was characterized using different analytical techniques like melting point, Infrared spectroscopy, Raman spectroscopy, powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, atomic absorption spectroscopy and mass spectrometry. An antibacterial study of the complex was also studied for its possible use in medical treatment. KEY WORDS: Silver complex, Acetyl coumarin, Vibrational analysis, Antibacterial study Bull. Chem. Soc. Ethiop. 2016, 30(3), 403-411DOI: http://dx.doi.org/10.4314/bcse.v30i3.

Effect of Permeation Enhancers on the Release Behavior and Permeation Kinetics of Novel Tramadol Lotions

Purpose: The aim of this research work was to formulate, characterize and evaluate the in vitro permeation behavior of tramadol lotion containing propylene glycol (PG) and polyethylene glycol (PEG) as permeation enhancers.Methods: The permeation experiments were conducted in vitro using full thickness rabbit skin in Franz diffusion cells. The donor compartment was filled with PBS (phosphate buffered saline) at pH 7.4 ± 0.1. The receptor phase was continuously stirred PBS (pH 7.4) at 37 °C ± 0.5. The amount of tramadol permeated into the receptor phase was determined spectrophotometrically at 271 nm. Various permeation parameters such as permeation coefficient (Kp), diffusion coefficient (D), flux (J), input rate,and enhancement ratio were obtained using Fick’s diffusion laws.Results: Permeation increased with increase in the concentrations of both enhancers tested. Maximum cumulative amount permeated for control lotion (Lc) was 357 ìg/cm2/min with input rate 0.574 ìg/min and lag time (tlag) of 34.93 min, while for the optimum test lotion (L4, containing 8 % PG/PEG in ratio of 1:1 v/v), it was 926 ìg/cm2/min, 1.482 ìg/min and 58.36 min, respectively. The significantly (p < 0.05) higher permeability shown by the test lotion L4 can be attributed, in part, to the interaction of PG withintercellular lipids leading to the disruption of their organization and increasing their fluidity, and also partly as a result of solubilization of lipid bilayers by PEG.Conclusion: A binary system of PG and PEG in lotion can be successfully utilized for the permeation enhancement of tramadol.Keyword: Tramadol, Transdermal delivery, Permeation, Propylene glycol, Polyethylene glycol, Rabbit skin