Set Of Representative Parameters Research Articles

Fluctuating orders and quenched randomness in the cuprates

We study a quasi-2D classical Landau-Ginzburg-Wilson effective field theory in the presence of quenched disorder in which incommensurate charge-density wave and superconducting orders are intertwined. The disorder precludes long-range charge-density wave order, but not superconducting or nematic order. We select three representative sets of input parameters and compute the corresponding charge-density wave structure factors using both large-$N$ techniques and classical Monte Carlo simulations. Where nematicity and superconductivity coexist at low temperature, the peak height of the charge-density wave structure factor decreases monotonically as a function of increasing temperature, unlike what is seen in X-ray experiments on YBa$_2$Cu$_3$O$_{6+x}$. Conversely, where the thermal evolution of the charge-density wave structure factor qualitatively agrees with experiments, the nematic correlation length, computed to one-loop order, is shorter than the charge-density wave correlation length.

Input Parameters for the Simulation of Silicon Solar Cells in 2014

Within the silicon photovoltaics (PV) community, there are many approaches, tools, and input parameters for simulating solar cells, making it difficult for newcomers to establish a complete and representative starting point and imposing high requirements on experts to tediously state all assumptions and inputs for replication. In this review, we address these problems by providing complete and representative input parameter sets to simulate six major types of crystalline silicon solar cells. Where possible, the inputs are justified and up-to-date for the respective cell types, and they produce representative measurable cell characteristics. Details of the modeling approaches that can replicate the simulations are presented as well. The input parameters listed here provide a sensible and consistent reference point for researchers on which to base their refinements and extensions.

Mathematical model for smoking: Effect of determination and education

We propose and analyze mathematical models to study the dynamics of smoking behavior under the influence of educational programs and also individual's determination to quit smoking. We establish the positivity and boundedness of the solutions in a biologically feasible region. A threshold value responsible for persistence of smoking is obtained and stability analysis on models is performed. We find that determination alone is not enough to eradicate smoking but it can reduce the prevalence of smoker population. Whereas the increase in education can possibly eradicate it. We performed numerical simulation for representative set of parameters to verify and discuss results obtained analytically.

Gamma-Index Passing Rates in Baseline Plans Measured with a Detector Array

Purpose: This study provides a simple protocol for validation of the gamma passing rates and to identify the optimum values of % dose and mm criteria for dose distributions measured with a detector array. Methods: We chose ArcCHECK detector array to illustrate the concepts. We used plans with uniform or quasi-uniform dose distributions along the detector array for testing in the presence of dose errors. For testing sensitivity to spatial shift we employed a plan with approximately constant dose gradient along the axis of the instrument. Results: We identified a representative set of parameters which describe performance of a detector array. We determined the minimum gamma-index acceptance criteria allowing the passing rates to reach 100% in the absence of errors, and identified the minimum fully detectable errors for such criteria. For our baseline plans delivered to ArcCHECK, 100% passing rates were obtained for 1.5% dose criterion together with ±3% minimum error detectable at 100% rate, and for 1.5 mm criterion together with the minimum fully detectable error of ±3 mm. We inspected the impact of selected program options on the passing rates. Conclusions: The protocol we developed provides a simple method of commissioning-style analysis of a detector array without a need for analysis of a large number of clinical plans.

THE KRAMERS-HEISENBERG FORMULA AND THE GUNN-PETERSON TROUGH

Recent cosmological observations indicate that the reionized universe may have started at around z = 6, where a significant suppression around Lyα has been observed from the neutral intergalactic medium. The associated neutral hydrogen column density is expected to exceed 10 21 cm ?2 , where it is very important to use the accurate scattering cross section known as the Kramers-Heisenberg formula that is obtained from the fully quantum mechanical time-dependent second order perturbation theory. We present the Kramers-Heisenberg formula and compare it with the formula introduced in a heuristic way by Peebles (1993) considering the hydrogen atom as a two-level atom, from which we find a deviation by a factor of two in the red wing region far from the line center. Adopting a representative set of cosmological parameters, we compute the Gunn-Peterson optical depths and absorption profiles. Our results are quantitatively compared with previous work by Madau & Rees (2000), who adopted the Peebles approximation in their radiative transfer problems. We find deviations up to 5 per cent in the Gunn-Peterson transmission coefficient for an accelerated expanding universe in the red off-resonance wing part with the rest wavelength △λ ∼ 10 A.

Numerical prediction of the stress–strain response of a lamellar γTiAl polycrystal using a two-scale modelling approach

Abstract An advanced model incorporating a two-scale structural description with integrated constitutive formulations of crystal plasticity was adopted to describe the mechanical behaviour of a γTiAl polycrystal with grains of staggered (γ/α2)-phase lamellae. The numerical model assembles a polycrystalline compound of 64 lamellar grains generated from periodic unit cells (PUC) taking relevant phase configurations. The representative parameter set for the crystal plasticity are estimated by modelling the lamellar deformation and fitting the compression and tension test results in two steps: firstly, the fundamental parameters were identified for a poly-synthetically twinned single crystal (PST) under compression, and secondly, these PST parameters were adjusted to the γTiAl polycrystal consisting of fully lamellar grains. Numerical results show that the compression–tension anomaly in the stress–strain curves can be successfully described by a ‘high-grade’ PUC model including six domain variants of the γ-phase occurring in the lamellae. Using a PUC model with simplified mapping of lamellar microstructure, the prediction quality remains unsatisfactory with respect to the observed compression and tension anomaly and the crystal parameters are found to be inconsistent. Differently aligned lamellar grains in polycrystalline cubic model are predicted, which showed that the global stress–strain curves are weakly affected by different local alignments (or textures) of the grains, whereas, the single grain analyses show strong variations in local stress–strain curves. The simulated nature of local variations in grain scale stress–strain behaviour accords with the independent results from instrumented indentation testing of the same lamellar polycrystal.

Complex scalar dark matter in aB-Lmodel

In this work, we implement a complex scalar Dark Matter (DM) candidate in a $U(1)_{B-L}$ gauge extension of the Standard Model. The model contains three right handed neutrinos with different quantum numbers and a rich scalar sector, with extra doublets and singlets. In principle, these extra scalars can have VEVs ($V_{\Phi}$ and $V_{\phi}$ for the extra doublets and singlets, respectively) belonging to different energy scales. In the context of $\zeta\equiv\frac{V_{\Phi}}{V_{\phi}}\ll1$, which allows to obtain naturally light active neutrino masses and mixing compatible with neutrino experiments, the DM candidate arises by imposing a $Z_{2}$ symmetry on a given complex singlet, $\phi_{2}$, in order to make it stable. After doing a study of the scalar potential and the gauge sector, we obtain all the DM dominant processes concerning the relic abundance and direct detection. Then, for a representative set of parameters, we found that a complex DM with mass around $200$ GeV, for example, is compatible with the current experimental constraints without resorting to resonances. However, additional compatible solutions with heavier masses can be found in vicinities of resonances. Finally, we address the issue of having a light CP-odd scalar in the model showing that it is safe concerning the Higgs and the $Z_{\mu}$ boson invisible decay widths, and also the energy loss in stars astrophysical constraints.

Stability of the multiple star system ι UMa (ADS 7114)

The physical and orbital parameters of the quadruple star system ι UMa (HD 76644 = ADS 7114) were determined earlier, when it was concluded based on modeling the system’s dynamics and applying theoretical stability criteria that the system was probably unstable. Here the stability of the ι UMa system is studied by calculating the Lyapunov characteristic exponents for representative sets of parameters and initial conditions. The conclusions on the system’s stability (or instability) based on various stability criteria and the calculated Lyapunov exponents are compared. The instability of the system as a whole is confirmed rigorously based on massive computations of the Lyapunov exponents. This system appears to be the only known multiple system whose instability has been rigorously established. The Lyapunov time-disruption time statistical relations are constructed, which show that the Hamiltonian intermittency of the second kind dominates. Typical disruption times are shorter than 1000 years, and the Lyapunov times are shorter than 100 years.

Phase-merging enhanced harmonic generation free-electron laser

Together with one of its variants, the recently proposed phase-merging enhanced harmonic generation (PEHG) free-electron laser (FEL) is systematically studied in this paper. Different from a standard high-gain harmonic generation scheme, a transverse gradient undulator is employed to introduce a phase-merging effect into the transversely dispersed electron beam in PEHG. The analytical theory of the phase-merging effect and the physical mechanism behind the phenomenon are presented. Using a representative set of beam parameters, intensive start-to-end simulations for soft x-ray FEL generation are given to illustrate the performance of PEHG. Moreover, some practical issues that may affect the performance of PEHG are also discussed.

Low mass pseudoscalar dark matter in an extendedB−Lmodel

We study an extended $B\ensuremath{-}L$ model, which has in its structure four neutral scalars. In this model, a representative set of parameters enable us to conclude that one of these scalars is a promising candidate for low-mass dark matter. We introduce a ${Z}_{2}$ symmetry, which ensures the stability of the dark matter. The dominant annihilation process will be through the $s$ channel of the Scalar boson exchange in $b\overline{b}$. So, this is also a Higgs-portal dark matter model, but the Higgs decay to dark matter is suppressed and meets the constraints from invisible decays of the Higgs boson. The model is also in agreement with the constraints established by the XENON100, CoGeNT, and CDMS experiments, matching the relic abundance and the cross section with the nucleon.

A Bayesian approach for identifying drip emitter insertion head loss coefficients

The use of a Bayesian approach to identify the emitter insertion head loss coefficients required for the design of drip laterals is demonstrated. Total discharge and pressure measurements taken along commercially available 100 m rolls of pressure compensating drip laterals laid on a 1% slope wooden platform were used. The Metropolis–Hastings Markov Chain Monte Carlo algorithm was used to sample the parameters from the posterior distributions. An average emitter discharge exponent parameter was estimated as 0.1, and only 2 out of the 6 laterals examined had an average emitter discharge below the range published by the manufacturer. Due to statistical variability inherent in the emitter properties along the laterals, as a result of the manufacturing process, the generated parameters for the downhill and uphill directions of the same lateral were slightly different. A representative parameter set of the lateral type examined were generated from the joint posterior distribution of the 4 statistically similar laterals (as judged by overlapping of their paired k – α hydraulic parameter space) using their combined data sets. It was observed that the range (0.95–1.17) of the emitter insertion head loss coefficient identified by the Bayesian approach was similar to that published by the manufacturer (0.95–1.12), demonstrating to the power of the methodology. Simulation of pressures along the laterals and the total discharges yielded an average absolute error of 6.1% in pressure and 3.1% in total discharge for the 4 statistically similar laterals, while the errors were over three times higher for the remaining laterals. • A Bayesian approach to identify emitter head loss coefficient α is presented. • Identified emitter parameters could be different for the two flow directions. • 2 out of 6 laterals had an average emitter discharge below their expected value. • The emitter discharge exponent of the pressure compensating lateral was about 0.1. • The range of α (0.95–1.17) identified is identical to the published range (0.95–1.12).

Calculating extra (quasi)moduli on the Abrikosov-Nielsen-Olesen string with spin-orbit interaction

Using a representative set of parameters we numerically calculate the low-energy Lagrangian on the world sheet of the Abrikosov-Nielsen-Olesen string in a model in which it acquires rotational (quasi)moduli. The bulk model is deformed by a spin-orbit interaction generating a number of "entangled" terms on the string world sheet.

Reaktionsmuster des Oberkiefers von Säuglingen mit einseitigen Lippen-Kiefer-Gaumen-Spalten nach 3-D-Modellanalyse

In order to visualize and quantify the direction and extent of morphological upper-jaw changes in infants with unilateral cleft lip and palate (UCLP) during early orthodontic treatment, a three-dimensional method of cast analysis for routine application was developed. In the present investigation, this method was used to identify reaction patterns associated with specific cleft forms. The study included a cast series reflecting the upper-jaw situations of 46 infants with complete (n=27) or incomplete (n=19) UCLP during week 1 and months 3, 6, and 12 of life. Three-dimensional datasets were acquired and visualized with scanning software (DigiModel®; OrthoProof, The Netherlands). Following interactive identification of landmarks on the digitized surface relief, a defined set of representative linear parameters were three-dimensionally measured. At the same time, the three-dimensional surfaces of one patient series were superimposed based on a defined reference plane. Morphometric differences were statistically analyzed. Thanks to the user-friendly software, all landmarks could be identified quickly and reproducibly, thus, allowing for simultaneous three-dimensional measurement of all defined parameters. The measured values revealed that significant morphometric differences were present in all three planes of space between the two patient groups. Patients with complete UCLP underwent significantly larger reductions in cleft width (p<0.001), and sagittal growth in the complete UCLP group exceeded sagittal growth in the incomplete UCLP group by almost 50% within the first year of life. Based on patients with incomplete versus complete UCLP, different reaction patterns were identified that depended not on apparent severities of malformation but on cleft forms.

Impacts of Predictive Genomic Classifier Performance on Subpopulation-Specific Treatment Effects Assessment

We consider three (strong, moderate and mild) predictive biomarker scenarios with varying prevalence. As such, there is no treatment effect in the biomarker negative (g −) patient subpopulation. Relative to g −, there is a four-fold profound treatment effect in the biomarker positive (g +) patient subpopulation, a strongly predictive scenario; a three-fold large g + subpopulation treatment effect, a moderately predictive scenario; and a two-fold modest g + subpopulation treatment effect, a mildly predictive scenario. In this paper, we focus on binary endpoint in prescribing treatment effect. Using a Breiman’s (Mach. Learn. 24:123–140, 1996) machine learning voting algorithm via a k-fold cross-validated approach applied by Freidlin et al. (Clin. Cancer Res. 16:691–698, 2010), a predictive biomarker may be developed. We consider development or discovery of a genomic biomarker using microarray gene expressions data in randomized controlled trials and validate the biomarker’s predictive performance in an independent data set. We investigate the classification performance characteristics of a binary genomic composite biomarker (expected to be predictive of treatment effects) including sensitivity, specificity, accuracy, positive predictive value and negative predictive value as a function of true sensitive prevalence. In doing so, we report the finding based on three representative tuning parameter sets with varying degree of rigor in their choices of the parameters ranging from highly rigorous, moderately rigorous to mildly rigorous. We articulate the rationales on the choices of tuning parameter sets. We also study the impacts of misclassification of genomic biomarker classifiers on their assessment of treatment effects in the positive and negative patient subpopulations, and all-comer patients. We elucidate via simulation studies on approaches to improve sensitivity when a biomarker is highly specific but poorly sensitive, a scenario that is most likely to lead to an incorrect test conclusion of an applicable significant treatment effect in a specific patient subpopulation or both positive and negative subpopulations. We explore when it will be beneficial to develop a binary predictive biomarker and conclude that hypothesis test inferences for the g + subpopulation treatment effect in the dual hypotheses setting (all-comer and g + alone) cannot be relied upon if the biomarker classifier is only highly specific and poorly sensitive or resulting in poor negative predictive value. The converse dual hypotheses (all-comer and g − alone) have the same concern, viz. highly sensitive and poorly specific or resulting in poor positive predictive value. In addition, we compare the predictive performance of a biomarker classifier between use of direct selection and selection from a candidate pool shedding favorable lights of direct selection approach where biological or mechanistic plausibility can be relied upon. Further research is needed if accurate classifier is required irrespective of prevalence level.

Runoff simulation considering time-varying partial contributing area based on current precipitation index

Summary Partial contributing area (PCA) denotes the region of a watershed near saturation and contributing surface flow to streams. The objective of this study was to incorporate the time-varying PCA concept into hydrological modeling for runoff simulation. In order to provide an accurate estimation of the temporal PCA ratio, a current precipitation index (CPI) was adopted to simulate the continuous change of water content in soil and to estimate the antecedent soil moisture at the beginning of a rainstorm. Information on the time-varying PCA ratio was then combined with a geomorphology-based runoff model for hydrograph simulation. The proposed model was applied to two watersheds, one in the United States of America and the other in Taiwan, to demonstrate its capability for runoff simulation. The results showed that the CPI can provide adequate estimations on time-varying PCA ratio. The simulated hydrographs of the test storms for the two study watersheds were found consistent with records. A set of representative parameters obtained from model calibration in the study watersheds can be a reference for practical uses in the watersheds with similar geomorphologic and hydrological conditions.

Dynamic approach to finite-temperature magnetic phase transitions in the extendedJ1−J2model with vacancy order

The recently discovered iron-based superconductors A(y)Fe(2-x)Se(2) (A=K, Rb, Cs, Tl) show a long-range antiferromagnetic order with an unexpectedly high transition temperature T(N)~550 K and a unique √5×√5 vacancy order. Taking the extended J(1)-J(2) model as a minimal model, we investigate the finite-temperature magnetic phase transitions in a square lattice with a √5×√5 vacancy superstructure by using large-scale Monte Carlo simulations. By the parallel tempering technique, the block spin checkerboard and stripe antiferromagnetic states are detected to be the ground states for three representative sets of model parameters. The short-time dynamic approach is applied to accurately determine the critical temperature as well as the static and dynamic exponents. Our results indicate that the dramatic enhancement of the critical temperature as observed in experiments should be mainly due to a combination of the vacancy order and the block lattice contraction.

Determination of air-void parameters of hardened cement-based materials using X-ray computed tomography

This paper presents an attempt to tackle limitations in the two-dimensional (2D) stereological characterization of the air-void parameters of hardened cement-based materials by employing three-dimensional (3D) X-ray computed tomography (CT), a technique capable of simultaneously imaging numerous sections within a specimen. Using three hardened cement paste specimens composed of different air-void systems, we performed sensitivity analyses in terms of the number of traverse lines employed for a single section and the number of sampling sections across the height of a specimen. Parameters for a single section converged rapidly as the number of traverse lines increased, although unacceptable variations were in evidence across multiple sections. When the number of sampling sections exceeded about 10, a set of representative air-void parameters was successfully obtained within a standard variation of less than 10% of average values. The spacing factor and air content measures obtained via CT image analysis were in good agreement with previously reported data and with the original spacing factors defined for 3D space. Some advantages found in the use of X-ray CT imaging for determining air-void parameters are discussed.

Generating stable attosecond x-ray pulse trains with a mode-locked seeded free-electron laser

Generation of attosecond x-ray pulses is attracting much attention within the x-ray free-electron laser (FEL) user community. We propose a novel scheme for the generation of coherent stable attosecond x-ray pulse trains in a seeded FEL, via a process of mode-locked amplification. Three modulators and two chicanes are used for generating separated attosecond scale microstructures in the electron beam using the beam echo effect. Such electron beam will produce high harmonic radiation with a comb of longitudinal modes at the very beginning of the radiator. By using a series of spatiotemporal shifts between the copropagating radiation and electron beam in the radiator, all these modes can be preserved and amplified to saturation. Using a representative realistic set of parameters, three-dimensional simulation results show that trains of 200 attosecond soft x-ray pulses with stable peak powers at gigawatt level can be generated directly from ultraviolet seed lasers. The even spacing between the attosecond pulses can be easily altered from subfemtosecond to tens of femtoseconds by slightly changing the wavelength of one seed laser.

Distributed hydrological modeling of a micro-scale rainforest watershed in Amazonia: Model evaluation and advances in calibration using the new HAND terrain model

Summary Three sections of the Asu catchment, which is located within the Cuieiras Reservation 80 km northwest of Manaus in Central Amazonia, Brazil, were gauged to create nested catchments of the first (0.95 km 2 ), second (6.58 km 2 ) and third (12.43 km 2 ) Strahler orders. As the Cuieiras reserve contains pristine tropical rainforest, hydrological data collected in these catchments offers an opportunity to test the Distributed Hydrology Soil Vegetation Model’s (DHSVM) ability to simulate hydrological responses, and to represent the spatial distribution of hydrological phenomena such as evapotranspiration, soil moisture and water table depth. Digital Elevation Model (DEM) data were obtained from the Shuttle Radar Topography Mission (SRTM) data. We used a novel approach to produce high resolution (30 m) soil and vegetation maps that enabled a representative set of relevant parameters to be acquired. These soil and vegetation maps were derived from a hydrologically normalized DEM through the HAND (Height Above the Nearest Drainage) technique, a new type of terrain model procedure. The DHSVM model was calibrated and validated using the second order watershed. To test the model’s ability to represent processes at different spatial scales, the parameter set derived from the calibration was used to simulate the discharge of the first and third order streams. Model simulations of soil moisture, groundwater levels and discharge were compared with observed data and exhibited satisfactory performance overall, with the exceptions of the predicted water table depth and the underestimation of peak flows during the wet season. The results from these DHSVM runs indicate that the model is applicable to tropical forests environments (equatorial climates, lowland watersheds with deep soil), which are quite distinct from the environments for which the model was developed (temperate climates, mountainous watersheds with shallow soil). The study also demonstrated that the HAND terrain model is a useful tool for representing the spatial distributions of key hydrological parameters.

Selection of a representative set of parameters for robust ordinal regression outranking methods

We introduce the concept of a representative set of parameters for multiple criteria outranking methods: ELECTREGKMS and PROMETHEEGKS which apply the principle of robust ordinal regression. We exploit the necessary and the possible results provided by these methods to choose a single instance of the preference model, which would represent all other compatible instances. The representative set of parameters is selected within an interactive preference-driven procedure which allows combining some pre-defined targets into different scenarios. Each target concerns enhancement of the results of robust ordinal regression. Precisely, the DM may emphasize either the advantage of some alternatives over the others, acknowledged by all compatible outranking models, or ambiguity in the comparison for some other pairs of alternatives. Selecting the representative set of parameters, we satisfy the desire of some DMs of assigning precise values to variables of the model. We also enable exploitation of the outranking relation for these parameters in order to arrive at a representative recommendation in a traditional way.