Abstract: Optical emission based on excitonic scattering processes becomes important in dense exciton systems in which the average distance between excitons is of the order of a few Bohr radii but still below the exciton screening threshold. The phenomena due to interactions among excited states play significant role in the emission near band edge of the material. The theory of two-exciton collisions for GaAs/AlGaAs quantum well systems is a mild attempt to understand the physics associated with the optical spectra due to excitonic scattering processes in these novel systems. The four typical processes considered give different spectral shape, peak position and temperature dependence of the emission spectra. We have used the theory of scattering together with the second order perturbation theory to derive the radiative power spontaneously emitted at an energy ħω by these processes. The results arrived at are purely qualitative in nature. The intensity of emitted light in quantum well systems varies inversely to the square of temperature, whereas in case of bulk materials it simply decreases with the temperature.
Abstract: All the available algorithms for blind estimation namely constant modulus algorithm (CMA), Decision-Directed Algorithm (DDA/DFE) suffer from the problem of convergence to local minima. Also, if the channel drifts considerably, any DDA looses track of the channel. So, their usage is limited in varying channel conditions. The primary limitation in such cases is the requirement of certain overhead bits in the transmit framework which leads to wasteful use of the bandwidth. Also such arrangements fail to use channel state information (CSI) which is an important aid in improving the quality of reception. In this work, the main objective is to reduce the overhead imposed by the pilot symbols, which in effect reduces the system throughput. Also we formulate an arrangement based on certain dynamic Artificial Neural Network (ANN) topologies which not only contributes towards the lowering of the overhead but also facilitates the use of the CSI. A 2×2 Multiple Input Multiple Output (MIMO) system is simulated and the performance variation with different channel estimation schemes are evaluated. A new semi blind approach based on dynamic ANN is proposed for channel tracking in varying channel conditions and the performance is compared with perfectly known CSI and least square (LS) based estimation.
Abstract: Risk response planning is of importance for software project risk management (SPRM). In CMMI, risk management was in the third capability maturity level, which provides a framework for software project risk identification, assessment, risk planning, risk control. However, the CMMI-based SPRM currently lacks quantitative supporting tools, especially during the process of implementing software project risk planning. In this paper, an economic optimization model for selecting risk reduction actions in the phase of software project risk response planning is presented. Furthermore, an example taken from a Chinese software industry is illustrated to verify the application of this method. The research provides a risk decision method for project risk managers that can be used in the implementation of CMMI-based SPRM.
Abstract: Transmission and distribution lines are vital links between the generating unit and consumers. They are exposed to atmosphere, hence chances of occurrence of fault in transmission line is very high which has to be immediately taken care of in order to minimize damage caused by it. In this paper Discrete wavelet transform of voltage signals at the two ends of transmission lines have been analyzed. The transient energy of the detail information of level five is calculated for different fault conditions. It is observed that the variation of transient energy of healthy and faulted line can give important information which can be very useful in classifying and locating the fault.
Abstract: Discharges in hydrogen, ignited by wire explosion, with current amplitude up to 1.5 MA were investigated. Channel diameter oscillations were observed on the photostreaks. Voltage and current curves correlated with the photostreaks. At initial gas pressure of 5-35 MPa the oscillation period was proportional to square root of atomic number of the initiating wire material. These oscillations were associated with aligned magnetic and gas-kinetic pressures. At initial pressure of 80-160 MPa acoustic pressure fluctuations on the discharge chamber wall were increased up to 150 MPa and there were the growth of voltage fluctuations on the discharge gap up to 3 kV simultaneously with it. In some experiments it was observed abrupt increase in the oscillation amplitude, which can be caused by the resonance of the acoustic oscillations in discharge chamber volume and the oscillations connected with alignment of the gaskinetic pressure and the magnetic pressure, as far as frequencies of these oscillations are close to each other in accordance with the estimates and the experimental data. Resonance of different type oscillations can produce energy density increasing in the discharge channel. Thus, the appropriate initial conditions in the experiment allow to increase the energy density in the discharge channel
Abstract: This research work is concerned with the eigenvalue problem for the integral operators which are obtained by linearization of a nonlocal evolution equation. The purpose of section II.A is to describe the nature of the problem and the objective of the project. The problem is related to the “stable solution" of the evolution equation which is the so-called “instanton" that describe the interface between two stable phases. The analysis of the instanton and its asymptotic behavior are described in section II.C by imposing the Green function and making use of a probability kernel. As a result , a classical Theorem which is important for an instanton is proved. Section III devoted to a study of the integral operators related to interface dynamics which concern the analysis of the Cauchy problem for the evolution equation with initial data close to different phases and different regions of space.
Abstract: We present linear codes over finite commutative rings
which are not necessarily Frobenius. We treat the notion of syndrome
decoding by using Pontrjagin duality. We also give a version of Delsarte-s
theorem over rings relating trace codes and subring subcodes.
Abstract: The study examines the determinants of corporate cash holding of non-financial quoted firms in Nigeria using a sample of fifty four non-financial quoted firms listed on the Nigeria Stock Exchange for the period 1995-2009. Data were sourced from the Annual reports of the sampled firms and analyzed using Generalized Method of Moments(GMM). The study finds evidence supportive of a target adjustment model and that firms can not instantaneously adjust towards the target cash level owing to the fact that adjustment cost being costly,. Also, the result shows significant negative relationship between cash holdings and firm size, net working capital, return on asset and bank relationship and positive relationship with growth opportunities, leverage, inventories, account receivables and financial distress. Furthermore, there is no significant relationship between cash holdings and cash flow. In Nigerian setting, most of the variables that are relevant for explaining cash holdings in the Developed countries are found by this study to be relevant also in Nigeria.
Abstract: Hydrodesulfurization (HDS) of dibenzothiophene
(DBT) in a high pressure batch reactor was done at 320 °C on
CoMoS/Al2O3-B2O3 (4, 10, and 16 wt. % of Boria) using nhexadecane
as solvent, dimethyldisulfide (DMDS) in tetradecane as
sulfur agent, and stirring at 1000 rpm. The effects of boria were
investigated by using X-ray diffraction (XRD), Temperature
programmed desorption (TPD) of ammonia, and Brunauer-Emmet-
Teller (BET) experiments. The results showed that the catalyst
prepared with low boria content (4 wt. %) had HDS activity (in
pseudo first order kinetic constant basis) value ~1.45 times higher to
that of CoMoS/Al2O3 catalyst.
Abstract: The geometric errors in the manufacturing process can
be reduced by optimal positioning of the fixture elements in the
fixture to make the workpiece stiff. We propose a new fixture layout
optimization method N-3-2-1 for large metal sheets in this paper that
combines the genetic algorithm and finite element analysis. The
objective function in this method is to minimize the sum of the nodal
deflection normal to the surface of the workpiece. Two different
kinds of case studies are presented, and optimal position of the
fixturing element is obtained for different cases.
Abstract: Remarkable changes, like the progress in the ability to understand others' minds, can be identified in several socio-cognitive dimensions between age four and seven. Recently, the parenting attitudes have been considerate as one of the potential extrinsic modifiers of these important developmental aspects. The aim of present study is to explore the relationship among authoritarian parenting attitudes and individual differences in Theory of Mind performance. The study included ninety-two Costarrican preschoolers. Six False-belief tasks, an Advanced Theory of Mind test and the Parenting Attitudes Inventory were used. The results demonstrate that participants with high and low Authoritarian Parenting Received differ in their performance on First and Second Order False-belief tasks, but not in Advanced Theory of Mind tasks. Theoretical considerations about possible explanations regarding these results are discussed and methodological limitations are considered to shed light over future directions.
Abstract: The scientific achievements coming from molecular
biology depend greatly on the capability of computational
applications to analyze the laboratorial results. A comprehensive
analysis of an experiment requires typically the simultaneous study
of the obtained dataset with data that is available in several distinct
public databases. Nevertheless, developing a centralized access to
these distributed databases rises up a set of challenges such as: what
is the best integration strategy, how to solve nomenclature clashes,
how to solve database overlapping data and how to deal with huge
datasets. In this paper we present GeNS, a system that uses a simple and yet innovative approach to address several biological data integration issues. Compared with existing systems, the main
advantages of GeNS are related to its maintenance simplicity and to its coverage and scalability, in terms of number of supported
databases and data types. To support our claims we present the current use of GeNS in two concrete applications. GeNS currently contains more than 140 million of biological relations and it can be
publicly downloaded or remotely access through SOAP web services.
Abstract: A talking head system (THS) is presented to animate
the face of a speaking 3D avatar in such a way that it realistically
pronounces the given Korean text. The proposed system consists of
SAPI compliant text-to-speech (TTS) engine and MPEG-4 compliant
face animation generator. The input to the THS is a unicode text that is
to be spoken with synchronized lip shape. The TTS engine generates a
phoneme sequence with their duration and audio data. The TTS
applies the coarticulation rules to the phoneme sequence and sends a
mouth animation sequence to the face modeler. The proposed THS can
make more natural lip sync and facial expression by using the face
animation generator than those using the conventional visemes only.
The experimental results show that our system has great potential for
the implementation of talking head for Korean text.
Abstract: Permanent magnet synchronous machines are known
as a good candidate for hybrid electric vehicles due to their unique
merits. However they have two major drawbacks i.e. high cost and
small speed range. In this paper an optimal design of a permanent
magnet machine is presented. A reduction of permanent magnet
material for a constant torque and an extension in speed and torque
ranges are chosen as the optimization aims. For this purpose the
analytical model of the permanent magnet synchronous machine is
derived and the appropriate design algorithm is devised. The genetic
algorithm is then employed to optimize some machine specifications.
Finally the finite element method is used to validate the designed
machine.
Abstract: The objective of present work is to stimulate the
machining of material by electrical discharge machining (EDM) to
give effect of input parameters like discharge current (Ip), pulse on
time (Ton), pulse off time (Toff) which can bring about changes in the
output parameter, i.e. material removal rate. Experimental data was
gathered from die sinking EDM process using copper electrode and
Medium Carbon Steel (AISI 1040) as work-piece. The rules of
membership function (MF) and the degree of closeness to the
optimum value of the MMR are within the upper and lower range of
the process parameters. It was found that proposed fuzzy model is in
close agreement with the experimental results. By Intelligent, model
based design and control of EDM process parameters in this study
will help to enable dramatically decreased product and process
development cycle times.
Abstract: The forest fires in Thailand are annual occurrence which is the cause of air pollutions. This study intended to estimate the emission from forest fire during 2005-2009 using MODerateresolution Imaging Spectro-radiometer (MODIS) sensor aboard the Terra and Aqua satellites, experimental data, and statistical data. The forest fire emission is estimated using equation established by Seiler and Crutzen in 1982. The spatial and temporal variation of forest fire emission is analyzed and displayed in the form of grid density map. From the satellite data analysis suggested between 2005 and 2009, the number of fire hotspots occurred 86,877 fire hotspots with a significant highest (more than 80% of fire hotspots) in the deciduous forest. The peak period of the forest fire is in January to May. The estimation on the emissions from forest fires during 2005 to 2009 indicated that the amount of CO, CO2, CH4, and N2O was about 3,133,845 tons, 47,610.337 tons, 204,905 tons, and 6,027 tons, respectively, or about 6,171,264 tons of CO2eq. They also emitted 256,132 tons of PM10. The year 2007 was found to be the year when the emissions were the largest. Annually, March is the period that has the maximum amount of forest fire emissions. The areas with high density of forest fire emission were the forests situated in the northern, the western, and the upper northeastern parts of the country.
Abstract: The present study is aim to prepare and evaluate the selfnanoemulsifying drug delivery (SNEDDS) system of a poorly water soluble drug valsartan in order to achieve a better dissolution rate which would further help in enhancing oral bioavailability. The present research work describes a SNEDDS of valsartan using labrafil M 1944 CS, Tween 80 and Transcutol HP. The pseudoternary phase diagrams with presence and absence of drug were plotted to check for the emulsification range and also to evaluate the effect of valsartan on the emulsification behavior of the phases. The mixtures consisting of oil (labrafil M 1944 CS) with surfactant (tween 80), co-surfactant (Transcutol HP) were found to be optimum formulations. Prepared formulations were evaluated for its particle size distribution, nanoemulsifying properties, robustness to dilution, self emulsication time, turbidity measurement, drug content and invitro dissolution. The optimized formulations are further evaluated for heating cooling cycle, centrifugation studies, freeze thaw cycling, particle size distribution and zeta potential were carried out to confirm the stability of the formed SNEDDS formulations. The prepared formulation revealed t a significant improvement in terms of the drug solubility as compared with marketed tablet and pure drug.
Abstract: In this paper, the data correction algorithm is suggested
when the environmental air temperature varies. To correct the infrared
data in this paper, the initial temperature or the initial infrared image
data is used so that a target source system may not be necessary. The
temperature data obtained from infrared detector show nonlinear
property depending on the surface temperature. In order to handle this
nonlinear property, Taylor series approach is adopted. It is shown that
the proposed algorithm can reduce the influence of environmental
temperature on the components in the board. The main advantage of
this algorithm is to use only the initial temperature of the components
on the board rather than using other reference device such as black
body sources in order to get reference temperatures.
Abstract: Thermo-chemical treatment (TCT) such as pyrolysis
is getting recognized as a valid route for (i) materials and valuable
products and petrochemicals recovery; (ii) waste recycling; and (iii)
elemental characterization. Pyrolysis is also receiving renewed
attention for its operational, economical and environmental
advantages. In this study, samples of polyethylene terephthalate
(PET) and polystyrene (PS) were pyrolysed in a microthermobalance
reactor (using a thermogravimetric-TGA setup). Both
polymers were prepared and conditioned prior to experimentation.
The main objective was to determine the kinetic parameters of the
depolymerization reactions that occur within the thermal degradation
process. Overall kinetic rate constants (ko) and activation energies
(Eo) were determined using the general kinetics theory (GKT)
method previously used by a number of authors. Fitted correlations
were found and validated using the GKT, errors were within ± 5%.
This study represents a fundamental step to pave the way towards the
development of scaling relationship for the investigation of larger
scale reactors relevant to industry.
Abstract: The phase diagrams and compositions of coexisting
phases have been determined for aqueous two-phase systems
containing poly(propylene glycol) with average molecular weight of
425 and sodium citrate at various pH of 3.93, 4.44, 4.6, 4.97, 5.1,
8.22. The effect of pH on the salting-out effect of poly (propylene
glycol) by sodium citrate has been studied. It was found that, an
increasing in pH caused the expansion of two-phase region.
Increasing pH also increases the concentration of PPG in the PPGrich
phase, while the salt-rich phase will be somewhat mole diluted.