Miracle-dz/UniFAR-FTUs huggingface dataset:
The standard H ∞ problem and the maximum principle: the general linear case

The classical, relatively simple ideas of linear quadratic (LQ) optimization are used in a time domain treatment of the standard$H_\infty $problem. Given the power of time domain analysis, the problem can be solved in the general framework of linear time varying, possibly infinite-dimensional, finite as well as infinite horizon systems, under no structural restrictions (such as block dimensions, zero blocks in the D operator, etc.). In the spirit of recent finite-dimensional linear time invariant (LTI) results, the solution is given in terms of two coupled Riccati equations; it includes a criterion for suboptimality and a parametrization of all suboptimal compensators. Results pertinent to LTI, periodic, and asymptotic systems are obtained as corollaries.
Current Status of Jet Noise Predictions Using Large-Eddy Simulation

A survey of the current applications of large-eddy simulation for the prediction of noise from single stream turbulent jets is given. After summarizing the numerical techniques used, the data predicted by the simulations are given at conditions from subsonic, heated jets to supersonic, unheated jets. Mach numbers between 0.3 and 2.0 are considered. Following the data presentation, an analysis of the trends exhibited by the data is given, with special attention paid to relationship between numerical and/or modeling choices and the prediction accuracy. The data support the conclusion that the most limiting factor in current large-eddy simulations is the thickness of the initial shear layer, which is commonly one order of magnitude thicker than what is found experimentally. There is also a large amount of uncertainty regarding the influence of the subgrid scale model on the predictions. The influence of inflow conditions is discussed in depth. Uncertainties in the inflow conditions currently prohibit the simulations from reliably predicting the potential core length. The centerline evolution of the mean and fluctuating axial velocity is strongly coupled to the resolution of the initial shear layers, but can be made to agree within experimental uncertainty when sufficiently thin initial shear layers are used. The maximum achieved Strouhal number of the sound in the acoustic far field is 1.5-3.0, depending on flow condition; this limit is due to numerical resources. A listing of some of the open questions and future directions concerning jet noise predictions using large-eddy simulation concludes the survey.
A new measurement of the flux of the light cosmic-ray nuclei at high energies

A new cosmic-ray detector utilizing a ring-imaging Cerenkov counter to determine the energy of light cosmic-ray nuclei was flown on high-altitude balloon from Fort Sumner, NM, in 1991 September. We describe the design and performance of this instrument and discuss the data analysis procedures. The measurement provides a new determination of the absolute flux and differential energy spectrum of the primary cosmic-ray species helium between 40 and 320 GeV/nucleon. The experiment also yields the spectra of carbon and oxygen and some information on the intensities of the secondary nuclei Li, Be, and B. A comparison between our results and previous measurements of heavier nuclei (Z greater than or equal to 4) from HEAO 3 and Spacelab 2 indicates good consistency between these measurements. The data set is compared with the results of a leaky box propagation model. We find good agreement with this model if the abundance of helium relative to oxygen at the source is taken to be 25 +/- 6 and if the source spectrum is given by a power law in energy proportional to E(exp -2.15).
Planar limit for SU(N) symmetric quantum dynamical systems

The spectrum of a quantum mechanical Hamiltonian with SU(N) symmetry is studied in the limit N→∞. A complete description is given for the states which transform according to (i) the scalar representation (singlet states) and (ii) the adjoint representation of SU(N) (’’adjoint’’ states). The eigenvalues of the singlet states are equally spaced with a finite gap ω (g) as N→∞. The spectrum of the adjoint states is equally spaced asymptotically for large excitations with the same gap ω (g). The first excitation of the adjoint states is lower than the first singlet excitation. An accidental degeneracy appears which is removed by 1/N corrections. We compute explicitly this splitting for the singlet states. In this formulation 1/N2 plays a role similar to h/ so that all computed quantities are related to the corresponding classical system. All the quantities which enter in the calculation of the spectrum are analytic near g=0 with the same radius of convergence.
Studies of internal gravity waves at Halley Base, Antarctica, using wind observations

At Halley Base, which is situated on the Brunt Ice Shelf in Antarctica, internal gravity waves are frequently observed in the stably stratified atmospheric boundary layer. In this paper, time series of wind speed and direction at a height of 8 m, observed from three meteorological masts, are used to determine some of the physical properties of the waves, such as their wavelengths, phase speeds and directions of propagation. The relationship of the results to various theories of the generation of internal gravity waves is considered. It is shown that the waves do not usually propagate in the direction of the surface wind; typically the direction of propagation is rotated about 45° clockwise from the wind vector. The waves most frequently propagate from a direction of about 135°, which is perpendicular both to the Hinge Line (line where the ice shelf meets the land) and to the ridges in the ice shelf, suggesting a topographic influence. It is shown that the waves obey a dispersion relation similar to that for neutral, trapped internal gravity waves.
Star formation in the Magellanic Clouds – IV. Protostars in the vicinity of 30 Doradus

From a magnitude-limited infrared survey of the 30 Doradus complex four candidate protostars have been identified. These are associated with dense knots in the nebular arcs, and have luminosities of 1-5 × 10 4 L ⊙ and masses of 15-20 M ⊙ . The results indicate that both the knots and the associated star formation are likely to be caused by the compression of interacting arcs of mass-loss winds from hot massive stars in the central cluster, and other nearby clusters. This mode of star formation differs from the classical star formation scenario within dense molecular clouds, and appears to be highly efficient
Proceedings of Meetings on Acoustics

In most wind instruments, the acoustic output is generated by airflow through a non-linear valve, whose sounding frequency is largely determined by resonances in the bore of the instrument (an acoustic duct downstream of the valve) and mechanical properties of the non-linear valve that converts DC to AC power. The player's vocal tract (a second duct, upstream) also has acoustic resonances, which in particular cases play a significant role in performance technique. For example, when executing advanced techniques (e.g. pitch-bending, altissimo playing) on the clarinet and saxophone, we showed that expert control of vocal tract resonances is essential for performance (Chen, Smith, & Wolfe, 2008. Science, 319, 726). To understand how such a tract-valve-bore system might interact during trumpet performance, we measured the acoustic impedance spectrum in seven trumpeters' mouths as they played normal notes, high-register notes and while pitch-bending below and above the normal note. Unlike the behavior seen in saxophonists and clarinetists, none of the trumpeters studied showed any systematic adjustment of their vocal tract resonances to the notes played. The much greater control that trumpeters have over the natural frequency of the vibrating valve may explain the difference with clarinetists and saxophonists.
Detection and modeling of leakage current in AlGaN-based deep ultraviolet light-emitting diodes

Current-voltage (IV) characteristics of two AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) with differing densities of open-core threading dislocations (nanopipes) are analyzed. A three-diode circuit is simulated to emulate the forward-bias IV characteristics of the DUV-LEDs, but is only able to accurately model the lower leakage current, lower nanopipe density DUV-LED. It was found that current leakage through the nanopipes in these structures is rectifying, despite nanopipes being previously established as inherently n-type. Using defect-sensitive etching, the nanopipes are revealed to terminate within the p-type GaN capping layer of the DUV-LEDs. The circuit model is modified to account for another p-n junction between the n-type nanopipes and the p-type GaN, and an excellent fit to the forward-bias IV characteristics of the leaky DUV-LED is achieved.
A Comparative Study on the Components of the Revised M.A. English Translation Curriculum in Asian Universities

The current master’s curriculum in English Translation major in Iranian universities has not satisfied the demands of the society in which it was developed. Translation students have complained that some essential skills are not considered in the curriculum. Therefore, this study is aimed at proposing some guidelines for curriculum reformers in Iran to update the curriculum. To investigate effective components for updating the curriculum, it is necessary to focus on the curricula of other universities in foreign countries and compare them with that of Iran. For this aim, a qualitative-comparative analysis is used to compare the revised master’s curriculum of English Translation in Iran with seven prominent Asian universities, to investigate the strength and weaknesses of the curriculum in Iran, and to recognize the effective components included in the curriculum of those seven prominent universities to be recommended to update the curriculum of Iranian universities. Hence, the curricula of eight universities have been compared with five criteria, including the title of the Master’s degree, the number of credits, the course structure, the instructional objectives, and the course content. Results show that to update the curriculum of Iranian universities, a list of courses and instructional objectives needs to be added to train translators who can work with technological tools. To achieve this objective, a course named “co-translator software” should be added to the curriculum. The other objective is to improve students’ interpretation skills, which are accessible by adding a course in interpretation. The findings provide novel information for Iranian curriculum reformers to work on updating the curriculum.
A comparative study of isolation performance of electric automobile seat’s suspension added by negative-stiffness structure models

To evaluate the isolation performance of the negative-stiffness structure (NSS) used by the tuned-mass-damper (NSS-TMD) and the air pistons (NSS-AP) on improving the ride quality of the electrical automobile (EA), an EA’s dynamics model is built under the excitation of the road surface roughness and the in-wheel-motor. Based on the root mean square value of the driver’s seat acceleration response used to assess the driver’s ride quality, two models of the seat suspension added by NSS-AP and NSS-TMD are then simulated to compare the performance between NSS-TMD and NSS-AP in enhancing the ride quality of the EA. The study indicates that both NSS-TMD and NSS-AP added to the seat suspension improve the driver’s ride quality better than the seat suspension without the NSS. Particularly, the root mean square value of the driver’s seat acceleration with the NSS-AP is smaller than that of NSS-TMS by 17.2%. Additionally, when the EA is traveling on the road surfaces of ISO level A, level B, and level C with a high velocity of over 70 km/h, the root mean square value of the driver’s seat acceleration with the NSS-AP is also slowly increased and slower than that of the NSS-TMD. Moreover, the root mean square value of the driver’s seat acceleration with the NSS-AP is also reduced in comparison with the NSS-TMD under the change of the total mass of the in-wheel-motor and the rotor’s eccentricity. Thereby, the NSS-AP improves the EA’s ride quality better than the NSS-TMD; and the NSS-AP should be used on the seat suspension of the EA to further enhance the ride quality.
The Vlasov‐Poisson‐Boltzmann system near Maxwellians

The dynamics of dilute electrons can be modeled by the Vlasov‐Poisson‐Boltz‐mann system, where electrons interact with themselves through collisions and with their self‐consistent electric field. It is shown that any smooth, periodic initial perturbation of a given global Maxwellian that preserves the same mass, momentum, and total energy (including both kinetic and electric energy), leads to a unique global‐in‐time classical solution. The construction of global solutions is based on an energy method with a new estimate of dissipation from the collision: ∫0t〈Lf(s), f(s)〉ds is positive definite for solution f(t,x,v) with small amplitude to the Vlasov‐Poisson‐Boltzmann system (1.4). © 2002 Wiley Periodicals, Inc.
Acceleration by pulsar winds in binary systems

In the absence of accretion torques, a pulsar in a binary system will spin down due to electromagnetic dipole radiation and the spin-down power will drive a wind of relativistic electron-positron pairs. Winds from pulsars with short periods will prevent any subsequent accretion but may be confined by the companion star atmosphere, wind or magnetosphere to form a standing shock. The authors investigate the possibility of particle acceleration at such a pulsar wind shock and the production of VHE and UHE gamma rays from interactions of accelerated protons in the companion star's wind or atmosphere. They find that in close binaries containing active pulsars, protons will be shock accelerated to a maximum energy dependent on the pulsar spin-down luminosity. If a significant fraction of the spin-down power goes into particle acceleration, these systems should be sources of VHE and possibly UHE gamma rays. The authors discuss the application of the pulsar wind model to binary sources such as Cygnus X-3, as well as the possibility of observing VHE gamma-rays from known binary radio pulsar systems.
Orientation estimation for instrumented helmet using neural networks

This work presents an integrated solution for head orientation estimation, which is a critical component for applications of virtual and augmented reality systems. The proposed solution builds upon the measurements from the inertial sensors and magnetometer added to an instrumented helmet, and an orientation estimation algorithm is developed to mitigate the effect of bias introduced by noise in the gyroscope signal. Convolutional Neural Network (CNN) techniques are introduced to develop a dynamic orientation estimation algorithm with a structure motivated by complementary filters and trained on data collected to represent a wide range of head motion profiles. The proposed orientation estimation method is evaluated experimentally and compared to both learning and non-learning-based orientation estimation algorithms found in the literature for comparable applications. Test results support the advantage of the proposed CNN-based solution, particularly for motion profiles with high acceleration disturbance that are characteristic of head motion.
Magnetic field evolution in white dwarfs

The evolution of magnetic fields in a star experiencing radial contraction and cooling into a 0.6 solar mass white dwarf phase is examined analytically. An MHD equation is defined for a radially contracting star with a weak poloidal field that does not disturb the structure or evolution of the star. The distribution of conductivity within the star is approximated. A Newton-Raphson finite difference code is used to track the evolution of the star by iterative solution of the radial equation. A deconvolution algorithm is defined to track the decay eigenmodes. The central conductivity of a star increases rapidly, decreasing the decay time scale beyond the age of the star. Dominance of successively lower eigenmodes can cause multiple reversals in the surface field. 43 references.
Micromechanical Analysis of the Shear Behavior of a Granular Material

A distinct element analysis of the behavior of a granular material was performed by simulating direct shear tests of a dense and a loose 2D sample of 1,050 cylinders. Macroscopic results exhibit typical features of the shear response of granular materials: a perfect plasticity state that does not depend on the initial density, a peak stress and a dilatant behavior in the case of the dense sample, and a contractant behavior of the loose sample. A micromechanical analysis of the shear behavior was carried out based on the simulation results. Using the particle displacements and rotations, a shear band is located within the sample. Special attention is focused on the evolution of particle/particle contact orientation as well as on the direction of particle/particle contact forces. The shear process induces a clear change of contact and contact force orientations. A strong correlation between the induced anisotropy of the microstructure and the macroscopic loading is evident in the simulation results.
Analysis of Carrier Traps in Si3N4 in Oxide/Nitride/Oxide for Metal/Oxide/Nitride/Oxide/Silicon Nonvolatile Memory

The energy level, density and attempt to escape frequency of carrier traps in an Si3N4 film in tunnel oxide/nitride/oxide (ONO) multilayer for metal/oxide/nitride/oxide/silicon (MONOS) nonvolatile memory are investigated by discharging current transient spectroscopy (DCTS). To analyze the electrical properties of carrier traps observed through DCTS, a new model including the tunneling probability of the tunnel oxide film between the Si3N4 film and an Si substrate was proposed. As a result, the electron traps in the Si3N4 film, which are assumed to be related to the threshold voltage decay, i.e. data retention, were found for the first time. The energy level of the electron traps in the Si3N4 film in the ONO multilayer was 0.8–0.9 eV from the conduction band and the density was 1–5×1018 cm-3. The attempt to escape frequency of 2×1014 s-1 was also obtained. The energy level of the hole traps and its density were 0.8–0.9 eV from the top of the valence band and 1–4×1018 cm-3, respectively. The magnitude of the trap density obtained from DCTS shows good agreement with that obtained from memory hysteresis characteristics. These results indicate that their carrier traps are amphoteric traps.
Prediction of natural frequencies for thin circular cylindrical shells

Abstract In this paper an analytical procedure is given to study the free-vibration characteristics of thin circular cylindrical shells. Ritz polynomial functions are assumed to model the axial modal dependence and the Rayleigh-Ritz variational approach is employed to formulate the general eigenvalue problem. Influence of some commonly used boundary conditions, viz. simply supported-simply supported, clamped-clamped and clamped-free, and also the effects of variations of shell parameters on the vibration frequencies are examined. Natural frequencies for a number of particular cases are evaluated and compared with some available experimental and other analytical results in the literature on this topic. These results are given in the form of tables and figures. A very good agreement between the results of the present analysis and the corresponding experimental and analytical results available in the literature is obtained to confirm the validity and accuracy as well as the efficiency of the method.
Cirrus Cloud Radiative and Microphysical Properties from Ground Observations and In Situ Measurements During FIRE 1991 and Their Application to Exhibit Problems in Cirrus Solar Radiative Transfer Modeling

Abstract Measurements from the FIRE 1991 cirrus cloud field experiment in the central United States are presented and analyzed. The first part focuses on cirrus microphysical properties. Aircraft 2D-probe in situ data at different cloud altitudes were evaluated for cirrus cases on four different days. Also presented are simultaneous data samples from balloonborne videosondes. Only these balloonsondes could detect the smaller crystals. Their data suggest (at least for midlatitude altitudes below 10 km) that ice crystals smaller than 15 μm in size are rare and that small ice crystals not detected by 2D-probe measurements are radiatively of minor importance, as overlooked 2D-probe crystals account for about 10% of the total extinction. The second part focuses on the link between cirrus cloud properties and radiation. With cloud macrophysical properties from surface remote sensing added to the microphysical data and additional radiation measurements at the surface, testbeds for radiative transfer models were .
Analysis of the histopathological findings of lymph node biopsies at a tertiary care centre

Background: Lymph nodes are spread throughout the body and are routinely checked for abnormalities. These lymph nodes have the potential to become infected or malignant. The swelling of lymph nodes and the nodes which are abnormal in terms of size and/or number is commonly known as lymphadenopathy. One of the most common causes of lymphadenopathy observed is reactive lymphadenitis followed by granulomatous lymphadenitis. For diagnosis of lymph node biopsies, excisional biopsy and histopathological analysis are considered as the ‘gold standard’. Methods: This is a retrospective, descriptive and a cross-sectional study of all the patients with lymph node biopsies seen in Bhaktivedanta Hospital and Research Institute from January 2018 till March 2022. Histopathology reports of lymph node biopsies of patients required at Bhaktivedanta Hospital and Research Institute were included in the study. Results: The most common diagnosis is of tuberculous lymphadenitis which accounted for 251 (53.2%) of the total 469 cases. Tuberculous lymphadenitis was most commonly observed in females (68.92%) as compared to males (31.07%). Cancer cases which accounted for 83 (17.70%) cases formed the second most common diagnosis in which females (53.01%) accounted for most cases as compared to males (46.99%). Conclusions: Enlarged lymph nodes should undergo fine needle aspiration cytology (FNAC), truecut biopsy and/or excisional biopsy for correct diagnosis. The diagnostic spectrum ranges from benign reactive to TB and also malignancies.
Salary cost evaluation by means of non-homogeneous semi-Markov processes

A useful model for forecasting the future development of salary costs in a firm is presented in this paper. This problem is relevant in the field of pension funds and also when a company decides to change the structure of its workforce. In the latter case, it might be necessary to forecast future salary costs in the new organizational hierarchy. The problem is solved by means of a special kind of stochastic process. To be more precise, this paper presents a generalization of discrete time non-homogeneous semi-Markov processes and of the related reward process. This new stochastic process is able to take in account all the aspects of the problem.
Steady particulate flows in a horizontal rotating cylinder

Results of discrete element method (DEM) simulation and magnetic resonance imaging (MRI) experiments are compared for monodisperse granular materials flowing in a half-filled horizontal rotating cylinder. Because opacity is not a problem for MRI, a long cylinder with an aspect ratio ∼7 was used and the flow in a thin transverse slice near the center was studied. The particles were mustard seeds and the ratio of cylinder diameter to particle diameter was approximately 50. The parameters compared were dynamic angle of repose, velocity field in a plane perpendicular to the cylinder axis, and velocity fluctuations at rotation rates up to 30 rpm. The agreement between DEM and MRI was good when the friction coefficient and nonsphericity were adjusted in the simulation for the best fit.