Miracle-dz/UniFAR-FTUs huggingface dataset:
Optimal partitioning method for stability analysis of continuous/discrete delay systems

This paper is concerned with the problem of stability analysis for continuous‐time/discrete‐time systems with interval time‐varying delay. Based on the idea of partitioning the delay interval into l nonuniform subintervals, new Lyapunov functionals are established. By utilizing the reciprocally convex approach to deal with the delay information in each subinterval, sufficient stability conditions are proposed in terms of linear matrix inequalities. Based on these criteria, the optimal partitioning method is given on the basis of the genetic algorithm. Finally, the reduced conservatism of the results in this paper is illustrated by numerical examples. Copyright © 2013 John Wiley & Sons, Ltd.
Optically induced gratings in Fe‐ and Mn‐doped Bi4Ge3O12 single crystals

Optically induced gratings have been created in Bi4Ge3O12 single crystals doped with Fe and Mn impurities. The writing kinetics of the holograms depends on the previous illumination with ultraviolet (UV) light, λ=310 nm. It has been concluded that there is a photorefractive contribution due to Fe impurities ([Fe]=2.7×1017 atoms/cm3) which can be observed when the holograms are written with 457.9 nm light. This contribution is essentially independent of the previous UV illumination, the steady state diffraction efficiency η of a 633 nm He‐Ne laser beam is ≊2×10−4, and the corresponding modulation of the refractive index Δn at λ=633 nm is ≊4×10−6. The UV illumination induces a transient behavior of the diffraction efficiency with ηmax≊8×10−4, this regime is dominated by the photorefractive effect. After this maximum, η decreases to ≤0.3×10−4 and a quasi steady state is reached; in this steady state regime the contribution of a photochromic grating dominates the value of η. Mn‐doped samples ([Mn]=4.3×1017 at.
An Investigation on Heat Transfer Characteristics of Fin and Tube Heat Exchangers Using the Geometry Similitude Method

Air conditioners are recently required to be efficient and more compact due to regulation reinforcement on energy consumption of home appliances. This tendency has promoted the development of the enhanced heat exchanger with a better performance. This study experimentally investigates the effects of the shape of interrupted surface fins on the performance of the fin and tube type heat exchanger used as home air conditioner. The scaled-up model experiment was conducted to measure the heat transfer coefficient and pressure drop. Results show that this experiment is very useful to estimate the heat transfer characteristics of the fin and tube heat exchanger. It is also found that the slit fin has a better performance than any other fin type used in the air conditioners. The heat transfer in the fin with an interrupted surface is influenced by the parameters such as the forming area of interrupted surfaces, the type of interrupted surfaces, slit patterns and slit raised direction, and thus affect the overall heat exchanger performance.
Constraints on the impact of radar rainfall data assimilation on forecasts of cumulus convection

Experience from operational trials of assimilation of radar data in kilometre‐scale numerical weather prediction models (operating without cumulus parametrization) shows that the positive impact of the radar data on convective precipitation forecasts typically decays within a few hours, although certain cases show much longer impact time‐scales. In this work the impact time of radar data assimilation is related to characteristics of the meteorological environment. Three cases of convection over southern Germany with different synoptic conditions are investigated (one case with two data assimilation cut‐off times), each with an ensemble of ten forecasts at 2.8 km horizontal resolution based on different initial and boundary conditions from a global forecast ensemble. Control forecasts are compared with forecasts where radar rainfall data are assimilated using latent heat nudging. The impact time of the radar data on total precipitation is quantified, and found to correlate well with a convective time‐scale that measures the rate at which convection is responding to changes in large‐scale forcing. Short impact times were associated with short convective time‐scales that are characteristic of equilibrium convection. In this regime the statistical properties of the convection are constrained by the large‐scale forcing, and effects of the radar data are lost within a few hours as the convection rapidly returns to equilibrium. When the convective time‐scale was large (non‐equilibrium conditions), the impact of the radar data was longer since convective systems were triggered by the latent heat nudging and were able to persist for many hours in the very unstable conditions present in these cases. The impact of the assimilated radar data on the location of precipitation was assessed using the equitable threat score (ETS) and the displacement and amplitude score (DAS). The impact times for these measures were consistently shorter than for total precipitation, but again shortest for the equilibrium conditions. Copyright © 2011 Royal Meteorological Society
The effect of front ZnO:Al surface texture and optical transparency on efficient light trapping in silicon thin-film solar cells

This study addresses the material properties of magnetron-sputtered aluminum-doped zinc oxide (ZnO:Al) films and their application as front contacts in silicon thin-film solar cells. Optimized films exhibit high conductivity and transparency, as well as a surface topography with adapted light-scattering properties to induce efficient light trapping in silicon thin-film solar cells. We investigated the influence on the ZnO:Al properties of the amount of alumina in the target as well as the substrate temperature during sputter deposition. The alumina content in the target influences the carrier concentration leading to different conductivity and free carrier absorption in the near infrared. Additionally, a distinct influence on the film growth of the ZnO:Al layer was found. The latter affects the surface topography which develops during wet-chemical etching in diluted hydrochloric acid. Depending on alumina content in the target and heater temperature, three different regimes of etching behavior have been i.
A PIEZOELECTRIC INHOMOGENEITY INTERACTING WITH A BRANCHED CRACK

This paper deals with the interaction between a circular piezoelectric inhomogeneity (a circular piezoelectric fiber sensor) and a symmetrically branched crack. The piezoelectric inhomogeneity is embedded in a nonpiezoelectric, elastic matrix with a symmetrically branched crack near the inhomogeneity. The matrix is under a far field in-plane uniform tensile stress and an anti-plane electric field. By using the solution of a single dislocation interacting with an inhomogeneity as Green's function, the main crack and its two symmetrical branches are simulated by continuously distributed edge dislocations. The formulation results in a group of singular integral equations (SIEs). Through solving the singular integral equations numerically, the unknown distributed dislocation density functions can be obtained, and both the Mode I and Mode II stress intensity factors at the branch tips are thus evaluated. The influence of materials constants, geometrical configurations, as well as the far field electric and mechanical loading on the interaction between the branched crack and the piezoelectric inhomogeneity is discussed in detail. As the derivation procedure is very tedious, the analytical results obtained are verified by finite element computation.
Phase of reflection high-energy electron diffraction oscillations during (Ba,Sr)O epitaxy on Si(100): A marker of Sr barrier integrity

We use the reflection high-energy electron diffraction oscillation phase shift to monitor the stability of the Sr barrier, prepared by exposure of Si(100) to Sr at high temperatures, in situ during molecular beam epitaxy growth of (Ba,Sr)O on Si(100). Our results confirm that the deposition of additional metallic Sr at low temperature is essential for preventing the incorporation of the Sr termination layer in the (Ba,Sr)O layer during its growth, and for obtaining monolayer thin (Ba,Sr)O layers with good crystallinity and minimal density of interfacial Si–O bonds on Si(100).
A New Hot-start Interior-point Method for Model Predictive Control*

Abstract In typical model predictive control applications, a finite-horizon optimal control problem, in the form of a quadratic program (QP), must be solved at each sampling instant with a known initial state. We present a new hot-start strategy to solve such QPs using interior-point methods, where the first interior-point iterate is constructed from a backward time-shifting of the solution to the QP at the previous time-step. There are two difficulties with such a strategy. First, a naive backward shifting of a previous solution can yield an initial iterate on the boundary of the primal-dual feasible region, leading to blocking of the search direction and consequently to very small and inefficient interior-point steps. Second, a backward shifted solution does not provide a set of strictly feasible terminal KKT conditions. In order to address both of these issues, we propose a modification to the basic backward-shifting method which provides simultaneously an initial iterate that satisfies strict feasibility conditions and a strictly feasible set of primal and dual terminal decision variables. Numerical results indicate that the proposed technique yields convergence in fewer iterations than a cold-start interior-point method.
Interaction of Colloidal Gold Nanoparticles with Urine and Saliva Biofluids: An Exploratory Study

The use of gold nanoparticles for drug delivery, photothermal or photodynamic therapy, and biosensing enhances the demand for knowledge about the protein corona formed on the surface of nanoparticles. In this study, gold nanospheres (AuNSs), gold nanorods (AuNRs), and gold nanoflowers (AuNFs) were incubated with saliva or urine. After the interaction, the surface of gold nanoparticles was investigated using UV-VIS spectroscopy, zeta potential, and dynamic light scattering. The shifting of the localized surface plasmon resonance (LSPR) band, the increase in hydrodynamic diameter, and the changes in the surface charge of nanoparticles indicated the presence of biomolecules on the surface of AuNSs, AuNRs, and AuNFs. The incubation of AuNFs with saliva led to nanoparticle aggregation and minimal protein adsorption. AuNSs and AuNRs incubated in saliva were analyzed through liquid chromatography with tandem mass spectrometry (LC-MS/MS) to identify the 96 proteins adsorbed on the surface of the gold nanoparticles. Among the 20 most abundant proteins identified, 14 proteins were common in both AuNSs and AuNRs. We hypothesize that the adsorption of these proteins was due to their high sulfur content, allowing for their interaction with gold nanoparticles via the Au-S bond. The presence of distinct proteins on the surface of AuNSs or AuNRs was also investigated and possibly related to the competition between proteins present on the external layers of corona and gold nanoparticle morphology.
Ginga observations of Centaurus X-3

Attention is given to a series of observations of Centaurus X-3 made with Ginga on March 22-24, 1989, over a complete orbital cycle. The data set includes a preeclipse dip, the eclipse ingress and egress, the eclipse itself, and a phase of high steady emission after egress. The mideclipse ephemeris obtained yields an estimate of the rate of change of the orbital period of -(1.738 +/- 0.004) x 10 exp 6/yr, confirming the rate of change reported by Kelley et al. (1983) and improving the precision by a factor of 20. The pulse profiles obtained with Ginga during the high postegress phase are double-peaked at low energies, and show a reversal of phase of 180 deg. No pulsations are detected during the eclipse and at low energies during the preeclipse dip, indicating that X-ray emission at these phases is due to scattering by extended matter. The energy of the iron emission line varies between 6.5 and 6.7 keV during the observation, while its equivalent width varies between 0.18 and 1.5 keV.
Characterization of a silicon strip detector for photon-counting spectral CT using monoenergetic photons from 40 keV to 120 keV

Background: We are developing a segmented silicon strip detector that operates in photon-counting mode and allows pulse-height discrimination with 8 adjustable energy bins. In this work, we determine the energy resolution of the detector using monoenergetic x-ray radiation from 40 keV to 120 keV. We further investigate the effects of pulse pileup and charge sharing between detector channels that may lead to a decreased energy resolution. Methods: For each incident monochromatic x-ray energy, we obtain count spectra at different photon fluxes. These spectra corresponds to the pulse-height response of the detector and allow the determination of energy resolution and charge-sharing probability. The energy resolution, however, is influenced by signal pileup and charge sharing. Both effects are quantified using Monte Carlo simulations of the detector that aim to reproduce the conditions during the measurements. Results: The absolute energy resolution is found to increase from 1.7 to 2.1 keV for increasing energies 40 keV to 120 keV at the lowest measured photon flux. The effect of charge sharing is found to increase the absolute energy resolution by a factor of 1.025 at maximum. This increase is considered as negligibly small. The pileup of pulses leads to a deterioration rate of the energy resolution of 4 · 10-3 keV Mcps-1 mm2, corresponding to an increase of 0.04keV per 10 Mcps increase of the detected count rate.
Massively parallel fabrication of repetitive nanostructures: nanolithography for nanoarrays

This topical review provides an overview of nanolithographic techniques for nanoarrays. Using patterning techniques such as lithography, normally we aim for a higher order architecture similarly to functional systems in nature. Inspired by the wealth of complexity in nature, these architectures are translated into technical devices, for example, found in integrated circuitry or other systems in which structural elements work as discrete building blocks in microdevices. Ordered artificial nanostructures (arrays of pillars, holes and wires) have shown particular properties and bring about the opportunity to modify and tune the device operation. Moreover, these nanostructures deliver new applications, for example, the nanoscale control of spin direction within a nanomagnet. Subsequently, we can look for applications where this unique property of the smallest manufactured element is repetitively used such as, for example with respect to spin, in nanopatterned magnetic media for data storage. These nanostructures are generally called nanoarrays. Most of these applications require massively parallel produced nanopatterns which can be directly realized by laser interference (areas up to 4 cm2 are easily achieved with a Lloyd's mirror set-up). In this topical review we will further highlight the application of laser interference as a tool for nanofabrication, its limitations and ultimate advantages towards a variety of devices including nanostructuring for photonic crystal devices, high resolution patterned media and surface modifications of medical implants. The unique properties of nanostructured surfaces have also found applications in biomedical nanoarrays used either for diagnostic or functional assays including catalytic reactions on chip. Bio-inspired templated nanoarrays will be presented in perspective to other massively parallel nanolithography techniques currently discussed in the scientific literature.
Kalman Filter—Finite Element Method in Identification

The extended Kalman filter, which is essentially a method of sequential least-squares estimation, has been applied not only for dynamic parameter identification but also for static or dynamic system identification problems. In order to obtain the stable and convergent estimation in dynamic or static parameter identification problems, an extended Kalman filter-weighted local iteration procedure with an objective function (EK-WLI procedure) is previously proposed by writers. This paper investigates the procedure in geotechnical engineering problems, where the EK-WLI procedure is incorporated with the finite element method in order to identify unknown parameters. For the effectiveness of this proposed procedure, parameter identification problems are numerically analyzed for an elastic plain strain field represented by finite element models under several conditions. And numerical examples show the usefulness of this method in parameter identification of a plain strain field.
Synthesis of data-dependent filters for digital image processing and recognition

Linear filtering remains an attractive method of image recognition because of simplicity of its performance in standard computing systems. Moreover, even nonlinear procedures of image processing include, as a rule, linear filtering for preliminary selection and transformation of classifying signs and compression of processed information to acceptable values. The efficiency of linear filtering is defined mainly by the proper choice of filter set, that must correspond to the peculiarities of the problem. Generally, it is desired that the total number of filters used would be as small as possible. It seems promising to use filters, constructed for some optimum criterion which take into account the statistical properties of the general image population. A well known example of such an approach is given by the Karhunen-Loeve decomposition. It is evident, that KL-decomposition is optimal for representation of the images, not for their discrimination. We suggest the procedure of discriminant filters construction, based on an a priori classified training set, and present some results of its practical application.
Bivariate survival models induced by frailties

Abstract When two observed survival times depend via a proportional-hazards model on the same unobserved variable, called a frailty, this common dependence induces an association between the observed times. This article considers the class of bivariate survival distributions that can arise in this way, extends it to allow negative association, and shows that the observable bivariate distribution determines the unobserved frailty distribution up to a scale parameter. A cross-ratio function, easily estimated even from censored data, is the key to both the characterization results and inferential procedures and diagnostic plots that are introduced and illustrated by real examples. The models considered are the natural counterpart for survival data of the latent variable models that have long been used in factor analysis for continuous data or in latent structure analysis for binary data. The main distinguishing feature of survival data is the possibility of censoring, which makes the standard methods difficu.
Improving deep subwavelength imaging through terminal interface design of metallo-dielectric multilayered stacks

Abstract. Symmetric metallo-dielectric multilayered stacks (MDMS) are investigated to improve the spatial resolution of subwavelength imaging operated in canalization regime. Simulation results revealed that subwavelength imaging capability is very sensitive to the thickness and material of the MDMS terminal layers. Furthermore, the coupling and decoupling of the Bloch modes in MDMS, between the object and image space, strongly depend on the terminal layer parameters which can be tuned to achieve the optimal imaging improvement. In contrast to metal-dielectric periodic MDMS, using MDMS with the developed symmetric surface termination, subwavelength imaging with optimal intensity throughput and improved field spatial resolution (∼20.4%) can be obtained. Moreover, optical singularity, in the form of Poynting vector saddle point, has been found in the free space after lens exit for the two kinds of symmetric MDMS that exhibit improved superresolution imaging performance with 100% energy flux visibility. The improved subwavelength imaging capabilities, offered by this proposed termination design method, may find potential applications in the areas of biological imaging, sensing, and deep subwavelength lithography, and many others.
State High School Exit Examinations and NAEP Long-Term Trends in Reading and Mathematics, 1971-2004

In 23 states, members of the high school class of 2008 were required to pass a state high school exit examination (HSEE) to earn regular high school diplomas. Proponents of these policies claim that they improve student academic achievement, although critics argue that they reduce the quality of instruction without raising academic achievement. Using nationally representative data collected to facilitate the analysis of temporal achievement trends, the effects of minimum competency and more difficult state HSEEs on student achievement in mathematics and reading between 1971 and 2004 are evaluated. The potential disparate impacts of state HSEEs on the achievement of students by race/ethnicity, socioeconomic status, and prior academic achievement are examined in this study. No evidence is found for any effects of state HSEEs on achievement in either reading or mathematics at the mean or at the 10th, 20th, 80th, or 90th percentiles of the achievement distribution.
High resolution magnetic vector-field imaging with cold atomic ensembles

We present a magnetic field imaging technique based on spatially resolved detection of Larmor precession. An optically trapped, elongated, and cold atomic sample of rubidium serves as magnetic field probe. We detect Larmor precession with a spatial and a temporal resolution of ∼50μm and ∼120μs, respectively. Projection-noise limited absorption imaging, feasible with current technologies, implies a sensitivity of ∼10pT/Hz at 50μm resolution; addition of an optical lattice could give ∼300fT/Hz sensitivity.
Energy optimal control of serial manipulators avoiding collisions

A non-linear programming approach to energy optimal control of serial manipulators is introduced that prevents collision of manipulator and spatial obstacles. Attention is given to the description of spatial obstacles and the definition of a distance measure thereupon. The generalized coordinates of the manipulator model are approximated by suitable ansatz functions. Thus the optimal control problem, a boundary value problem, is transformed to a constrained algebraic non-linear programming problem in terms of the ansatz function parameters. The constraints arise from the collision detection. The approach is applicable to redundant and non-redundant manipulators and can be extended to parallel manipulators.
Evidence for Extinct Vanadium-49 in Presolar Silicon Carbide Grains from Supernovae

We report Si, Ca, and Ti-V isotopic data for seven presolar silicon carbide grains of type X separated from the Murchison CM2 meteorite. The silicon carbide X grains most likely formed in the ejecta of Type II supernova explosions as indicated by large isotopic anomalies. The X grains of this study have 29Si/28Si and 30Si/28Si ratios of 0.56-0.75 and 0.41-0.62 times the solar value, respectively. Slight enrichments in 44Ca are observed, possibly due to the decay of radioactive 44Ti (t1/2 = 60 yr). While 46Ti/48Ti, 47Ti/48Ti, and 50Ti/48Ti ratios are close to solar, all X grains have enhanced 49Ti/48Ti ratios of up to 1.9 times the solar ratio. The 49Ti/48Ti ratios are positively correlated with 51V/48Ti ratios, suggestive of the incorporation of live 49V (t1/2 = 330 days) during silicon carbide condensation. This implies that the grains formed on a timescale of several months after supernova explosion.