Inference procedures for the Birnbaum–Saunders distribution and its generalizations

Goodness-of-fit tests are constructed for the two-parameter Birnbaum–Saunders distribution in the case where the parameters are unknown and are therefore estimated from the data. With each test the procedure starts by computing efficient estimators of the parameters. Then the data are transformed to normality and normality tests are applied on the transformed data, thereby avoiding reliance on parametric asymptotic critical values or the need for bootstrap computations. Two classes of tests are considered, the first class being the classical tests based on the empirical distribution function, while the other class utilizes the empirical characteristic function. All methods are extended to cover the case of generalized three-parameter Birnbaum–Saunders distributions.     

The exact discrete model of a system of linear stochastic differential equations driven by fractional noise

Abstract. This paper derives the exact discrete model (EDM) of a kth‐order system of stochastic differential equations driven by a vector fractional noise under fixed initial conditions. The EDM can be used for the Gaussian estimation and forecasting with long‐memory discrete‐time equispaced data. Detailed formulae which are necessary for the construction and numerical evaluation of the Gaussian likelihood under two observation schemes are established. State variables can be observed either at equispaced points in time or as integrals over the observational interval.     

Exponentially fitted Runge–Kutta methods for the numerical solution of the Schrödinger equation and related problems

Exponentially fitted Runge–Kutta methods for the numerical integration of the radial Schrödinger equation or systems of equations of the Schrödinger type and for the numerical solution of other related initial-value problems with periodic or oscillating solutions are developed in this paper. Numerical and theoretical results obtained for several well-known problems show the efficiency of the new methods.     

Developing a new library of materials and structural elements for the simulative evaluation of buildings’ energy performance

Contemporary building energy simulation programs are not only used by researchers but also are common tools in the hands of engineers and architects. Most of them are using databases of materials and structural elements, with characteristics originating from the country or the broader region where the specific program was developed. Thus, often the particularities met in other countries are not considered. Such a database of materials and constructions systematically used in the Greek building sector was developed for use with the simulation program EnergyPlus, which has become quite popular over the last years. In order to determine the applicability of the database, the energy behaviour of a typical multistory, multifamily building was simulated, having the exact materials and structural elements and patterns used in Greece. Furthermore, different thicknesses of insulation were simulated, corresponding to local climatic conditions and, even more important, to different dates of the building's construction. The results are presented and discussed in this paper.     

Regenerative properties of wavelength converters based on FWM in a semiconductor optical amplifier

A detailed experimental investigation of the regenerative properties of the four-wave mixing (FWM) for the conventional nonreturn-to-zero data format is reported. A key feature in the proposed scheme, and contrary to the conventional approach, is application of the ON-OFF keying modulation on the pump wave. Measurement of the static transfer functions of the FWM process in a semiconductor optical amplifier shows that certain operating regimes exist, mainly related to the power levels "one" and "zero" of the modulated pump, where a significant improvement of the extinction ratio (ER) can be achieved. This conclusion has been confirmed by dynamic measurements at 2.4 Gb/s, where up to 3-dB improvement in the ER has been observed.     

Brain mechanisms for reading and language processing in spina bifida meningomyelocele: A combined magnetic source- and structural magnetic resonance imaging study.

Objective: The development of the ability to process spoken and written language depends upon a network of left hemisphere temporal, parietal, and frontal regions. The present study explored features of brain organization in children with spina bifida meningomyelocele (SBM) and shunted hydrocephalus, who commonly present with precocious development of word reading skills and preservation of vocabulary and grammar skills. Method: Eight children with SBM were compared with 15 IQ and reading-level matched, typically developing controls on MRI-based morphometric and Magnetic Source Imaging-derived neurophysiological profiles. Results: Children with SBM showed reduced magnetic activity in left inferior parietal regions during spoken word recognition and pseudoword reading tasks. We also noted reduced surface area/volume in inferior parietal and posterior temporal regions in SBM and increased gray matter volumes in left middle frontal regions and gyral complexity in left posterior temporal and inferior parietal regions. Conclusions: A complex pattern of changes in cortical morphology and activation may serve as evidence for structural and functional brain reorganization ensuring preservation of language and decoding abilities in children with SBM. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Energy,environmental and economic optimization of thermal insulation solutions by means of an integrated decision support system

A new decision support system for the integrated assessment of thermal insulation solutions with emphasis on recycling potential is presented in this paper. The suggested system comprises three main assessment factors: primary energy consumption, the environmental impact and the financial cost; each and every factor is analytically assessed during the four distinct stages of a thermal insulation solution's life cycle. The calculation of the aforementioned factors takes place using analytical algorithms, formulated in such a way that have led to the development of the integrated, holistic decision-making support tool, namely ib3at. Using ib3at it becomes feasible to optimize the end-of-life management of thermal insulation solutions, but also to select, during the design phase of a new building, the optimal thermal insulation solution for each building element. The ib3at is applied for common thermal insulation practices, used widely in new constructions as well as in the renovation of existing buildings.     

An optimized explicit Runge–Kutta–Nyström method for the numerical solution of orbital and related periodical initial value problems

In this work a procedure for the construction of an explicit optimized Runge–Kutta–Nyström method with four stages and fifth algebraic order is provided. The variable coefficients of the preserved method result after nullifying the phase-lag, the dissipative error and the first derivative of the phase-lag. We can see the efficiency of the new method through its local truncation error. Furthermore, we compare the new method?s efficiency to other numerical methods. This is shown through the integration of the two-body problem with various eccentricities and of four other initial value problems.     

Dissipative exponentially-fitted methods for the numerical solution of the Schrödinger equation

The first dissipative exponentially fitted method for the numerical integration of the Schr?dinger equation is developed in this paper. The technique presented is a nonsymmetric multistep (dissipative) method. An application to the bound-states problem and the resonance problem of the radial Schr?dinger equation indicates that the new method is more efficient than the classical dissipative method and other well-known methods. Based on the new method and the method of Raptis and Allison (Comput. Phys. Commun. 14 (1978) 1-5) a new variable-step method is obtained. The application of the new variable-step method to the coupled differential equations arising from the Schr?dinger equation indicates the power of the new approach.     

40-gb/s NRZ and RZ operation of an all-optical AND logic gate based on a passive InGaAsP/InP microring resonator

The properties of an all-optical AND logic gate based on the four-wave mixing (FWM) effect in an InGaAsP/InP microring resonator side coupled to a bus waveguide are investigated. Using an ultrafast nonlinear process such as FWM, operation at a bit rate of 40 Gb/s is demonstrated for both nonreturn-to-zero (NRZ) and return-to-zero (RZ) modulation formats. The gate operation in terms of microring structural parameters and operating conditions is studied.