5,873 research outputs found

    Feasibility of valuing credit risk in the financial market in Sri Lanka: a case study

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    The Sri Lankan financial market uses non analytical techniques to quantify credit risk. Credit derivatives are not used to transfer credit risk. A Credit Default Swap (CDS) is the most widely used credit derivative to manage credit risk. To evaluate the price of CDS, various sophisticated methods are used. This research paper focuses on techniques to hedge credit risk in the Sri Lankan financial market, the behaviours of CDS in derivative markets, calculating a fair value of CDS, the main advantages of using credit derivatives, and major imperfections to use the pricing process of CDS in the Sri Lankan marke

    Optimal design of an aeroelastic wing structure with seamless control surfaces

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    This article presents an investigation into the concept and optimal design of a lightweight seamless aeroelastic wing (SAW) structure for small air vehicles. Attention has been first focused on the design of a hingeless flexible trailing edge (TE) control surface. Two innovative design features have been created in the SAW TE section: an open sliding TE and a curved beam and disc actuation mechanism. This type of actuated TE section allows for the SAW having a camber change in a desirable shape and minimum control power demand. This design concept has been simulated numerically and demonstrated by a test model. For a small air vehicle of large sweep back wing, it is noted that significant structural weight saving can be achieved. However, further weight saving is mainly restricted by the aeroelastic stability and minimum number of carbon/epoxy plies in a symmetric layup rather than the structural strength. Therefore, subsequent effort was made to optimize the primary wing box structure. The results show that an initial structural weight can be reduced significantly under the strength criterion. The resulting reduction of the wing box stiffness and aeroelastic stability and control effectiveness can be improved by applying the aeroelastic tailoring. Because of the large swept angle and resulting lightweight and highly flexible SAW, geometrical non-linearity and large bending-torsion aeroelastic coupling have been considered in the analysis

    Analysis of Economic Burden of Seasonal Influenza: An Actuarial Based Conceptual Model

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    Analysing the economic burden of the seasonal influenza is highly essential due to the large number of outbreaks in recent years. Mathematical and actuarial models can be considered as management tools to understand the dynamical behavior, predict the risk, and compute it. This study is an attempt to develop conceptual model to investigate the economic burden due to seasonal influenza. The compartment SIS (susceptible-infected-susceptible) model is used to capture the dynamical behavior of influenza. Considering the current investment and future medical care expenditure as premium payment and benefit (claim), respectively, the insurance and actuarial based conceptual model is proposed to model the present economic burden due to the spread of influenza. Simulation is carried out to demonstrate the variation of the present economic burden with respect to model parameters. The sensitivity of the present economic burden is studied with respect to the risk of disease spread. The basic reproduction is used to identify the risk of disease spread. Impact of the seasonality is studied by introducing the seasonally varying infection rate. The proposed model provides theoretical background to investigate the economic burden of seasonal influenza

    Developing a Decision Support Testing Algorithm to Detect Severity Level of Dengue

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    Dengue is a vector borne disease that has become a global threat. In order to reduce the mortality rate early detection of dengue severity level is crucial. This study is an extension of the decision models developed individually for inflammatory mediators and immune parameters. The objective of this study is to improve the individual models by considering their combined effect and to improve the decision making at 96 hours from onset of illness. In order to combine these, three approaches are attempted including, combining together the individual full models on inflammatory mediators and immune parameters, combining the immune parameters based model with decision tree informed cytokines and implementing a decision tree informed model with immune parameters and inflammatory mediators. The decision tree algorithm that is used in model development is Improved ID3 algorithm. The decision tree based model is a two-step decision system with the initial decision being made using the parameters TNF-?, IL-10, dengue NS1 antigen and dengue IgG antibody and, the operator values above 0.4413, are then subjected to the second test including platelet and Platelet Activating Factor. The decision tree based model performed well with an accuracy of 76.19% and 82.3% of DHF patients were correctly classified. Sensitivity analysis indicated the model to be robust

    Pluripotential Theory and Convex Bodies: A Siciak-Zaharjuta theorem

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    We work in the setting of weighted pluripotential theory arising from polynomials associated to a convex body PP in (R+)d({\bf R}^+)^d. We define the {\it logarithmic indicator function} on Cd{\bf C}^d: HP(z):=supJPlogzJ:=supJPlog[z1j1zdjd]H_P(z):=\sup_{ J\in P} \log |z^{ J}|:=\sup_{ J\in P} \log[|z_1|^{ j_1}\cdots |z_d|^{ j_d}] and an associated class of plurisubharmonic (psh) functions: LP:={uPSH(Cd):u(z)HP(z)=0(1), z}.L_P:=\{u\in PSH({\bf C}^d): u(z)- H_P(z) =0(1), \ |z| \to \infty \}. We first show that LPL_P is not closed under standard smoothing operations. However, utilizing a continuous regularization due to Ferrier which preserves LPL_P, we prove a general Siciak-Zaharjuta type-result in our PP-setting: the weighted PP-extremal function VP,K,Q(z):=sup{u(z):uLP, uQ on K}V_{P,K,Q}(z):=\sup \{u(z):u\in L_P, \ u\leq Q \ \hbox{on} \ K\} associated to a compact set KK and an admissible weight QQ on KK can be obtained using the subclass of LPL_P arising from functions of the form 1degP(p)logp\frac{1}{deg_P(p)}\log |p| (appropriately normalized)

    The detection of lubricating oil viscosity changes in gearbox transmission systems driven by sensorless variable speed drives using electrical supply parameters

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    Lubrication oil plays a decisive role to maintain a reliable and efficient operation of gear transmissions. Many offline methods have been developed to monitor the quality of lubricating oils. This work focus on developing a novel online method to diagnose oil degradation based on the measurements from power supply system to the gearbox. Experimental studies based on an 10kW industrial gearbox fed by a sensorless variable speed drive (VSD) shows that measurable changes in both static power and dynamic behaviour are different with lube oils tested. Therefore, it is feasible to use the static power feature to indicate viscosity changes at low and moderate operating speeds. In the meantime, the dynamic feature can separate viscosity changes for all different tested cases

    Towards a global model of accounting education

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    Purpose - The purpose of this paper is to examine the accounting education systems in three countries - Australia, Japan and Sri Lanka - to inform the development and testing (by application) of a Global Model of Accounting Education

    Theory of transient spectroscopy of multiple quantum well structures

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    A theory of the transient spectroscopy of quantum well (QW) structures under a large applied bias is presented. An analytical model of the initial part of the transient current is proposed. The time constant of the transient current depends not only on the emission rate from the QWs, as is usually assumed, but also on the subsequent carrier transport across QWs. Numerical simulation was used to confirm the validity of the proposed model, and to study the transient current on a larger time scale. It is shown that the transient current is influenced by the nonuniform distribution of the electric field and related effects, which results in a step-like behavior of the current. A procedure of extraction of the QW emission time from the transient spectroscopy experiments is suggested.Comment: 5 pages, 4 figures, to be published in J. Appl. Phy

    Comparison of Solvent-Free Microwave Extraction and Conventional Hydro-Distillation of Essential Oils from four Selected Underutilised Citrus sp. Plants

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    Essential oils (EOs) are widely used in cosmetic, pharmaceutical, fragrance and food industry. Solvent Free Microwave Extraction (SFME) is a green method for the extraction of essential oils from aromatic plants. The aim of the study is to compare SFME with conventional hydro-distillation (HD) technique, for the extraction of EO from four selected underutilised Citrus plant species in the essential oil industry; Citrus medica, C. reticulata, C. madurensis and C. limon in terms of chemical composition, antioxidant activity and energy consumption. The EOs were extracted using SFME (Microwave power: 700 W for 5 minutes and 400 W for 55 minutes) and HD (for 1 hour) and chemically analysed using Gas Chromatography (GC) and Gas Chromatography and Mass Spectrometry (GC-MS). The Antioxidant activity of the EOs were determined using Ferric Reducing Antioxidant Power (FRAP) and Total Polyphenolic Content (TPC) assays. The GC and GCMS identified 4(10)-Thujene (33.82%) as the major compound in C. medica oil, extracted by HD while that was L- terpinene-4-ol (18%) when extracted by SFME technique. The β-Linalool was the major component in C. reticulata (42.98%) and C. madurensis (37.95%) in SFME extracted EOs, however, it has been dropped down to 26.71% and 26.83% respectively during HD extraction. In C. limon, D-Limonene (43.069%) was abundant in HD- extracted EOs while it was (R)-(+)-Citronellal (39.08%) in SFME-extracted EO. SFME yielded EOs with higher amounts of more valuable oxygenated compounds with higher antioxidant capacities over HD. In comparison with HD, the SFME technique presented higher efficiency with reduced extraction times, costs and energy, yielding EOs with excellent chemical profiles and relatively high antioxidant activity.Keywords: Essential oils, Solvent free Microwave extraction, GC, GCMS, Antioxidan
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