Miracle-dz/UniFAR-FTUs huggingface dataset:
Pressure and temperature dependence of gain in InGaAs/GaAs laser diode

Wavelength dependent gain has been calculated for InGaAs/GaAs quantum‐well (QW) lasers as a function of hydrostatic pressure and temperature. The shift of the gain maximum for such laser is equal to −140 nm by increasing the pressure up to 20 kbar and −60 nm by cooling down from 300 to 100 K. The width of the gain curve (determining the possible tuning range with external grating) is significantly reduced at low temperatures and (to a lower extent) at high pressures. Our results indicate that pressure tuning is much more effective than temperature tuning when combined with tuning by external grating.
Planning Algorithms for a Class of Heterogeneous Multi-Vehicle Systems.

Abstract In this work we focuss on path and mission planning problems in scenarios in which two different vehicles with complementary capabilities are cooperatively employed so as to perform a desired task in an optimal way. In particular, we consider the case in which a vehicle carrier, typically slow but with virtually infinite operativity range, and a carried vehicle, which on the contrary is typically fast but with a shorter operative range, are coordinated to make the faster vehicle visit in the shortest time a certain collection of points. First, we will face a planning problem in which the order of the points to be visited is given a priori according to prescribed takeoff/landing conditions. Such a problem will be solved in an exact way by means of convex optimization arguments. Such a result will be the starting point to address a more complex mission planning problem, a Traveling Salesman Problem (TSP), in which the optimal visiting sequence of points has to be determined. For this latter problem a sub-optimal heuristic will be presented and its properties pointed out.
EVOLUTION OF THE GASEOUS CONTENT OF THE UNIVERSE

Results of a new spectroscopic survey for damped Ly-alpha absorption systems conducted at ultraviolet wavelengths are combined with those of previous surveys conducted at optical wavelengths in order to examine the evolution of the gaseous contnet of the universe at 0<~z<~3.5. Implicaitons for scenarios of galaxy formation and evolution are discussed.
Total variational blind image restoration from image sequences

Blind image restoration is to recover the original images from the blurred images when the blurring function in the image formation process is unknown. In this paper, we present an efficient and practical blind image restoration algorithm based on total variational (TV) regularization. The TV regularization employs TV norm on the images for the smoothness constraint, while the traditional regularization uses H1 norm for the smoothness constraint. The TV regularization provides a larger functional space for the image functions and is known for allowing discontinuities in the image function to be recovered. The blur functions considered in this paper are combinations of a Gaussian defocus blur and a uniform motion blur, that each can be approximated by a parametric function of one or two parameters. The use of this parametric form intrinsically imposes a constraint on the blur function. The small number of parameters involved in the parametric blur function makes the resulting optimization problem tractable. The above formulation for the restoration from a single image is then extended to the blind restoration from an image sequence by introducing motion parameters into the multi-frame data constraints. An iterative alternating numerical algorithm is developed to solve the nonlinear optimization problems. Each iteration of the alternating numerical algorithm involves the Fourier preconditioned conjugate gradient iterations to update the restored image and quasi-Newton steps to update the blur and motion parameters. Some experimental results are shown to demonstrate the usefulness of our algorithm.
Amplitude and phase calibration of hydrophones up to 70 MHz using broadband pulse excitation and an optical reference hydrophone

A substitution calibration technique for piezoelectric ultrasonic hydrophones is presented that uses an optical multilayer hydrophone as the reference receiver. Broadband nonlinearly distorted focused pulses are first measured with the reference hydrophone and then with the hydrophone to be calibrated. By Fourier transformation of the time wave forms and division of the frequency spectra, the complex-valued frequency response of the hydrophone under test is obtained in a broad frequency range in a very fast and efficient way and with high frequency resolution. The results obtained for a membrane hydrophone and a needle-type hydrophone are compared with those obtained by independent calibration techniques such as primary calibration using optical interferometry and secondary calibration using time-delay spectrometry, and good agreement is found. The calibration data obtained are apt to improve the results of ultrasound exposure measurements using broadband voltage-to-pressure conversion. This is demonstrat.
Model Predictive Control for Parallel Planning of Conflict-free Trajectories for Multiple Aircraft

This paper proposes a parallel model predictive control (MPC) scheme for planning conﬂict-free trajectories for multiple aircraft, in which each aircraft’s computer synchronously solves mixed-integer quadratically constrained quadratic programming (MIQCQP) problems. The main contribution of this paper is the formulation of compatibility constraints for the separation of aircraft, which guarantees recursive feasibility and enables synchronous calculations. More-over, the constraints on the velocity and acceleration, which are often overly simpliﬁed in existing studies, are tightly formulated in the framework of mixed-integer linear constraints. Through numerical simulations, the eﬀectiveness of the scheme is conﬁrmed in terms of the scalability, the recursive feasibility, and the validity of the trajectories.
A Lattice Boltzmann method for turbulent emulsions

The breakup of droplets in a turbulent flow is key to many natural and industrial applications. Here we present and validate a computationally efficient numerical method that allows to study turbulent emulsion for very long times. The numerical method is based on a multi-component Lattice Boltzmann method based on the Shan-Chen model and supplemented with a large scale force to stir turbulence. A special treatment to limit mobility between different fluid components is introduced and validated. We demonstrate the potential of our approach in sustaining a turbulent emulsion over extremely long integration times (necessary to collect firm turbulence statistics) and we present first results on the probability distribution function of droplets' accelerations.
Kinetics of island formation in organic film growth

Received 15 October 2007; revised manuscript received 1 January 2008; published 12 March 2008Three dimensional islands with ﬂat tops, steep edges, and a characteristic height are grown by organicmolecular beam deposition. The mesalike shape of the organic islands results from an efﬁcient ascendinginterlayer transport process, which originates from different effective step-edge binding energies of strainedlayers and unstrained layers. The molecules preferentially attach onto the upper step edges, which possesshigher effective binding energy with the molecules. Numerical simulations based on the model agree well withthe experimental results.DOI: 10.1103/PhysRevB.77. 113404 PACS number s : 68.43. Jk, 68.55. A , 81.05. Lg, 81.15. z
Modeling of the hydrogen maser disk in MWC 349

Maser amplification in a Keplerian circumstellar disk seen edge on-the idea put forward by Gordon (1992), Martin-Pintado, & Serabyn (1992), and Thum, Martin-Pintado, & Bachiller (1992) to explain the millimeter hydrogen recombination lines in MWC 349-is further justified and developed here. The double-peaked (vs. possible triple-peaked) form of the observed spectra is explained by the reduced emission from the inner portion of the disk, the portion responsible for the central ('zero velocity') component of a triple-peaked spectrum. Radial gradient of electron density and/or free-free absorption within the disk are identified as the probable causes of this central 'hole' in the disk and of its opacity. We calculate a set of synthetic maser spectra radiated by a homogeneous Keplerian ring seen edge-on and compare them to the H30-alpha observations of Thum et al., averaged over about 1000 days. We used a simple graphical procedure to solve an inverse problem and deduced the probable values of some basic disk and maser parameters. We find that the maser is essentially unsaturated, and that the most probable values of electron temperature. Doppler width of the microturbulence, and electron density, all averaged along the amplification path are, correspondingly, T(sub e) less than or equal to 11,000 K, V(sub micro) less than or equal to 14 km/s, n(sub e) approx. = (3 +/- 2) x 10(exp 7)/cu cm. The model shows that radiation at every frequency within the spectrum arises in a monochromatic 'hot spot. ' The maximum optical depth within the 'hot spot' producing radiation at the spectral peak maximum is tau(sub max) approx. = 6 +/- 1; the effective width of the masing ring is approx. = 0.4-0.7 times its outer diameter; the size of the 'hot spot' responsible for the radiation at the spectral peak frequency is approx. = 0.2-0.3 times the distance between the two 'hot spots' corresponding to two peaks. An important derivation of our model is the dynamical mass of the central star, M(sub *) approx. = 26 solar masses (D/1.2 kpc), D being the distance to the star. Prospects for improving the model are discussed.
Some common fixed point theorems for hybrid pairs of maps without the completeness assumption

Motivated by some recent works due to Singh and Kumar and Ahmed, the main result of Imdad and Ali is generalized and improved by removing the completeness assumption besides weakening the quasi-coincidentally commuting property of the involved hybrid pair to S-weak commutativity. Some illustrative examples are also furnished to support the genuineness of our extension besides deriving some related results.
Spin torque switching of 20 nm magnetic tunnel junctions with perpendicular anisotropy

Spin-transfer torque magnetic random access memory (STT-MRAM) is one of the most promising emerging non-volatile memory technologies. MRAM has so far been demonstrated with a unique combination of density, speed, and non-volatility in a single chip, however, without the capability to replace any single mainstream memory. In this paper, we demonstrate the basic physics of spin torque switching in 20 nm diameter magnetic tunnel junctions with perpendicular magnetic anisotropy materials. This deep scaling capability clearly indicates the STT MRAM device itself may be suitable for integration at much higher densities than previously proven.
A Fresnel propagation analysis of NFIRAOS/IRIS high-contrast exoplanet imaging capabilities

The thirty meter telescope (TMT) has the potential to find new planetary systems and to study them in greater details. It could also possibly image super-Earth planets around the closest stars or still accreting distant protoplanets around stars in very young star forming regions. Since no first generation dedicated exoplanet finding instrument has been selected for the TMT, initial direct exoplanet imaging will have to rely on the NFIRAOS facility adaptive optics (AO) system and IRIS spectro-imaging near-infrared (NIR) camera. End to-end Fresnel NFIRAOS simulations are presented using their current optical designs to evaluate the system multi-wavelength high-contrast imaging capabilities. Long exposures have been simulated using the expected AO-corrected phase screens and the estimated speckle lifetime. It is shown that NFIRAOS/IRIS may achieve contrasts close to the Gemini planet imager (GPI, an optimized NIR planet-finding instrument that will soon be installed on the Gemini South 8-m telescope), but needs to rely on multi-wavelength processing (by a factor 50) to achieve that goal, a challenging requirement. Without a coronograph and a better treatment of the in-band static speckle noise, it is unlikely that NFIRAOS/ IRIS will be able to achieve GPI-like contrasts at very small inner working angles, which is potentially accessible with a large 30-meter telescope. However, TMT, with its bigger aperture and better angular resolution, along with the current NFIRAOS/ IRIS designs, should be able to acquire higher SNR spectra and achieve three times better astrometric accuracy than GPI for medium to bright planets, resulting in better atmospheric characterization and faster orbital parameter determination of a sample of GPI planets.
OPtimum design for potential flows

Described in this paper is a methodology for solving a particular class of optimum design problems in Fluid Mechanics, namely optimum design problems for aerofoils when the corresponding fluid flow is potential. The methods described in this paper operate directly in the physical space, and take advantage of the variational formulation of the partial differential equation modelling the flow. The techniques of optimal control, optimization and the finite element method are used. Numerical examples are also given.
Solar Magnetism and the Activity Telescope at HSOS

A new solar telescope system is described, which has been operating at Huairou Solar Observing Station (HSOS), National Astronomical Observatories, Chinese Academy of Sciences (CAS), since the end of 2005. This instrument, the Solar Magnetism and Activity Telescope (SMAT), comprises two telescopes which respectively make measurements of full solar disk vector magnetic field and Hα observation. The core of the full solar disk video vector magnetograph is a birefringent filter with 0.1A bandpass, installed in the tele-centric optical system of the telescope. We present some preliminary observational results of the full solar disk vector magnetograms and Hα filtergrams obtained with this telescope system.
Optimization of white polychromatic semiconductor lamps

A stochastic method of optimization of a white-light source that relies on additive color mixing of the emissions from colored light-emitting diodes (LEDs) was developed. The method allows for finding the optimal wavelengths of LEDs in order to obtain the best possible trade off between luminous efficacy and the general color rendering index (CRI) of the white source for an arbitrary number of primary LEDs. Optimal solid-state lamps composed of two, three, four, and five different LEDs were analyzed. We show that a dichromatic LED lamp can only provide high efficacy with a general CRI close to zero, whereas trichromatic and quadrichromatic lamps are able to cover the entire range of reasonable general CRI values. The optimization of quintichromatic LED lamps and lamps with a higher number of primary color LEDs yields a negligible benefit in improving CRI but provides for quasicontinuous spectra that might be required for special lighting needs.
X-ray emission from the winds of hot stars

The kinematic model adopted in Paper I for the limiting amplitude state attained by the unstable line-driven winds of early-type stars is modified, a crucial but neglected physical effect is crudely taken into account, and the resulting x-ray spectra compared with observation. In this revised phenomenonlogical theory, radiatively driven shocks are conjectured to result from the amplification of unstable waves and to survive until shadowing by following shocks compels their decay. In consequence of this shock destruction mechanism, the revised theory predicts that x-ray emission continues far out into the nearly terminal flow; the effects of self-absorption-in particular, discontinuities at K-shell edges: are therefore not now expected to be prominent, a result qualitatively consistent with recent analyses of Einstein data. Nevertheless, with the preferred choice for the theory's single free parameter the x-ray luminosities calculated for several O stars are too low and the spectra too soft. These failures are interpreted as implying a broad spectrum of shock strengths, with the bulk of the x-ray emission coming from the strongest shocks.
La propriété de Bernoulli pour les endomorphismes de \mathsf{P}^k(\mathbb{C})

Soient f un endomorphisme holomorphe de degrée plus grand que 2, et \mu sa mesure d'équilibre. Alors (f,\mu) posséde la propriété de Bernoulli. Let f be a holomorphic self map of \mathsf{P}^k(\mathbb{C}), of degree greater than two and let \mu be its equilibrium measure. Then (f,\mu) is Bernoulli.
A comparison of Landsat ETM+ and high-resolution aerial orthophotos to map urban/suburban forest cover in Massachusetts, USA

This article examines the extent to which L(ow)-spatial resolution Landsat Enhanced Thematic Mapper Plus (ETM+) imagery can be used to map urban/suburban forest cover in comparison with H(igh)-spatial resolution (less than 1 m) digital aerial orthophotos from the same study area and time period. This research has practical implications for resource managers, government agencies and forestry researchers interested in mapping large-area urban/suburban forests because Landsat imagery is more accessible, has an extensive historical archive, has broader spatial and temporal coverage and is more cost efficient than H-resolution aerial orthophotos. Classification tree results suggest that Landsat ETM+ imagery is adequate for mapping larger, contiguous patches of forest (i.e. small forest patches greater than 2 acres) in urban/suburban settings, but its spatial resolution is too coarse to accurately map spatially complex residential areas in urban/suburban landscapes.
Geometric Cooperative Control of Formations

Abstract : Robots in a team are modeled as particles which obey simple, second order dynamics. The whole team can be viewed as a deformable body with changing shape and orientation. Jacobi shape theory is applied to model such a formation. The configuration space of the whole formation is then viewed as a fiber bundle on Jacobi shape space. Applications of shape theory to analyze problems, such as the sequential pursuit, provide insights on body motion and shape changes. We derive the controlled system equations using the Lagrange-D'Alembert principle. In the resulting Lagrangian equations, the motion of the center of mass of the formation is decoupled from the rotation and shape dynamics. Furthermore, control forces on each robot are combined and reorganized as controls for the center, for rotation and for shape changes. From a shape-theoretic point of view, general feedback control laws are designed to achieve desired formations. This class of feedback control laws induces interactions that can be computed in a distributed manner. When communication links and GPS are available to each robot, we use Jacobi vectors as feedback for control. We show that formations are set up asymptotically. The system equations on shape space provide possibilities for achieving formations without communication links between team members, under the assumption that each robot uses its sensors to measure shape and rotation of the formation. We allow each robot freedom to establish a coordinate system in which shape dynamics of the whole formation is computed. Without knowing such coordinate systems of other robots, each robot is able to perform cooperative control. This is made possible by a class of gauge covariant control laws. Using Lyapunov functions, we prove that controlled dynamics converges to an invariant set where desired shape is achieved. We argue that this freedom of choosing gauge frame helps to improve controller performance in a noisy environment.
A physical model for the middle ear cavity (MEC)

The input impedance of the cat MEC is modeled by approximating the bulls and tympanic cavities as a cascade of two cylindrical tubes. The small hole in the bony septum, known as the foramen, is approximated as a short cylindrical tube. Nonplanar wave propagation, due to the foramen, and visco‐thermal losses at the cavity walls are included in the model. The model was verified by making impedance measurements on cylindrical cavities for frequencies up to 12 kHz. The intact case, as well as the open bulls case and plugged foramen case, is simulated and shown to be in good agreement with animal measurements [T. J. Lynch, III, Ph.D. thesis, MIT (1981)]. in addition to the bulls resonance near 4.5 kHz, the model predicts that there is a second bulls resonance near 26 kHz. Without the bony septum, the resonances are shown to be near 10 and 20 kHz. It is hypothesized that the role of the foramen is to shift the resonant frequencies.
Low-cost photonic crystals for spectral sensors fabricated using projection lithography

Nanophotonic structures including photonic crystals and plasmonics have a lot of potential applications in spectral sensing. These devices typically require electron beam lithography, a slow process, for fabrication. Successful commercialization of these technologies requires reproducible, high volume fabrication. Projection lithography is an established process for rapid, reproducible patterning. We have successfully pushed the limits of projection lithography to develop a low-cost, high-throughput alternative to electron beam lithography for our nanoscale, visible-wavelength photonic crystal spectral sensors. The developed process is 100 times faster than electron beam lithography for 10mm by 10mm dies on a four inch wafer. Testing of the photonic crystals in spectral sensors shows uniformity in large scale production which is robust to defects from processing.
The tectonic evolution of the Tibetan Plateau

The Tibetan Plateau, between the Kunlun Shan and the Himalayas, consists of terranes accreted successively to Eurasia. The northernmost, the Songban Ganzi Terrane, was accreted to the Kunlun (Tarim-North China Terrane) along the Kunlun-Qinling Suture during the late Permian. The Qiangtang Terrane accreted to the Songban-Ganzi along the Jinsha Suture during the late Triassic or earliest Jurassic, the Lhasa Terrane to the Qiangtang along the Banggong Suture during the late Jurassic and, finally, Peninsular India to the Lhasa Terrane along the Zangbo Suture during the Middle Eocene. The Kunlun Shan, Qiangtang and Lhasa Terranes are all underlain by Precambrian continental crust at least a billion years old. The Qiangtang and Lhasa Terranes came from Gondwanaland. Substantial southward ophiolite obduction occurred across the Lhasa Terrane from the Banggong Suture in the late Jurassic and from the Zangbo Suture in the latest Cretaceous-earliest Palaeocene. Palaeomagnetic data suggest successive wide Palaeotethyan oceans during the late Palaeozoic and early Mesozoic and a Neotethys which was at least 6000 km wide during the mid-Cretaceous. Thickening of the Tibetan crust to almost double the normal thickness occurred by northward-migrating north-south shortening and vertical stretching during the mid-Eocene to earliest Miocene indentation of Asia by India; Neogene strata are almost flat-lying and rest unconformably upon Palaeogene or older strata. Since the early Miocene, the northward motion of India has been accommodated principally by north south shortening both north and south of Tibet. From early Pliocene to the Present, the Tibetan Plateau has risen by about two kilometres and has suffered east-west extension. Little, if any, of the India Eurasia convergence has been accommodated by eastward lateral extrusion.