Miracle-dz/UniFAR-FTUs huggingface dataset:
Digital controller for a magnetic suspension system

An active magnetic suspension system controlled digitally by a microprocessor has been built and operated in our laboratories. The control algorithm has integral, proportional, and derivative feedback loops. The remainder of the system including the sensor, power amplifier, and suspension coils, is of standard design. This developmental system has been used successfully to suspend small steel spheres and small rotors up to 190 g in weight, and shows promise of having wide application.
Fractal image compression based on wavelet transform

It is well known that images can be greatly compressed by exploiting the self-similar redundancies. In this paper, the self-similarities of wavelet transform are analyzed, and it is discovered that corresponding subbands of different scale detail signals are similar. An image coding method is proposed according to this property. The typical self-affirm transform is modified such that it is adapted to DWT coefficient encoding. An adaptive quantization method of the transform parameters s, is given. Firstly, a J-order discrete wavelet transform of the original image, denoted by LL0, is performed. That is, LL is decomposed into LLj + 1, LHj + 1, HL$_j + 1, for 0 <EQ j <EQ J - 1. Secondly, LLJ$. is encoded based on DCT. Thirdly, HL(subscript J LHJ and HHJ are quantized and run- length coded. Fourthly, HLj, LHj and HHj for 1 <EQ j <EQ J - 1, are encoded with modified self- similar transforms. HLj, LHj, and HHj are divided into non-overlapping range blocks. For each range block Ri (epsilon HLj, a domain block Dj (epsilon) HLj + 1, which best matches Rj, is found, and the parameter s1 of the corresponding transform is determined and adaptively quantized. Several kinds of images are compressed with this method. Experimental results demonstrate that this method can compress images significantly while keeping a very good fidelity. Besides, the algorithm is faster than typical fractal image coding methods because less searching is needed.
Eigenvalues of block structured asymmetric random matrices

We study the spectrum of an asymmetric random matrix with block structured variances. The rows and columns of the random square matrix are divided into D partitions with arbitrary size (linear in N). The parameters of the model are the variances of elements in each block, summarized in g∈R+D×D. Using the Hermitization approach and by studying the matrix-valued Stieltjes transform we show that these matrices have a circularly symmetric spectrum, we give an explicit formula for their spectral radius and a set of implicit equations for the full density function. We discuss applications of this model to neural networks.
Acquisition of internal representation by multilayered perceptrons

One of the characteristics of the PDP model (multilayer perceptron with backward error propagation learning) is thought to be its ability to automatically find a mapping between inputs and outputs based on input-output vector samples describing that mapping. However, since in the mapping the values of representative points are determined by table lookup, and the values of other points are determined by interpolation between them, it can be viewed as one type of Memory Based Reasoning. On the other hand, it is thought that the PDP model has the ability to extract features from the input vector. In this paper, the forementioned two points are investigated completely and it is demonstrated that entirely different results are obtained when the internal representation differs, even if the input data are exactly the same. It is stipulated that information processing in the PDP model is a process that carries out a transformation which represents the input vector distribution in an optimal metric space (internal representation) and interpolates that metric space. This internal representation acquisition capability is demonstrated by means of a simple simulation.
Uniaxial crystal last optical element for second- and third-generation immersion lithography

In this paper, we show that uniaxial crystals and sapphire in particular, can be used as a lens material for high-index immersion lithography. Although uniaxial crystals are birefringent and anisotropic for unpolarized light, under certain conditions they are fully isotropic for transverse electric (TE) polarizations. The strong birefringence of the uniaxial crystal defocuses the residual TM polarization relative to the TE mode so that its image does not reach the photoresist but rather creates a small background. To manifest this property, a combination of pupil-fill polarization constraints, mask design rules and crystal alignment requirements must be satisfied. Sapphire is a well-known industrial optical material featuring high optical quality and homogeneity. Its refractive index of 1.928 at 193 nm, along with its high thermal conductivity and moderate absorption, are close to industry requirements. An implementation of sapphire under these conditions is proposed, suggesting a path to the continued scaling of 193 nm lithography numerical aperture.
Laser beams with embedded vortices: tools for atom optics

Two-dimensional spatial light modulators have been employed to create static and dynamic phase masks for embedding multiple vortices and exotic intensity-void structures in laser beams. A variety of patterns of singularities, producing dark longitudinal and transverse intensity channels, have been created. The uniformity, quality, and suitability of these patterns as elements for atom optics (e.g., atom-tunnel beam splitters) have been studied as a function of the phase quantization level and spatial resolution of the phase mask. Specifically, we show that (1) high-quality modes, those that propagate long distances and can be focused, can be generated when the number of phase steps between 0 and 2pi on the phase mask exceed four and (2) atom confinement increases with the charge of the vortex.
Noncontact detection of laser-induced acoustic waves from buried absorbing objects using a dual-beam common-path interferometer

The feasibility of a noncontact all-optical probe for surface detection of laser-induced acoustic waves generated in buried absorbing objects was investigated. The goal is to detect subsurface optically absorbing objects, such as hemorrhages or vascularized tumors, which generate acoustic waves when slightly heated by a Q-switched laser pulse transported to an internal object by light diffusion within a turbid tissue. A dual-beam common-path interferometer was constructed to provide sensitive time-resolved detection of surface movements. Arrival of a pressure wave at one surface beam irradiation site before arrival at the other beam site caused a differential surface movement and a pathlength difference detected by the interferometer. The dynamic range of linear measurement was about 20 mbar - 200 bar at 20 mV/bar. The sensitivity (20 m V/bar) and noise level (10 - 30 mbar) of the interferometer matched or exceeded the performance of a lithium-niobate piezoelectric transducer. The point spread function of response was studied in liquid phantoms which demonstrated a null plane of no response in the plane symmetrically between the two beams. The ability to image an absorbing object at a depth of 11 mm within an aqueous phantom medium was demonstrated illustrating sub-mm resolution.
Inventory policies for two products under Poisson demand: Interaction between demand substitution, limited storage capacity and replenishment time uncertainty

We consider a two‐product inventory system with independent Poisson demands, limited joint storage capacity and partial demand substitution. Replenishment is performed simultaneously for both products and the replenishment time may be fixed or exponentially distributed. For both cases we develop a Continuous Time Markov Chain model for the inventory levels and derive expressions for the expected profit per unit time. We establish analytic expressions for the profit function and show that it satisfies decreasing differences properties in the order quantities, which allows for a more efficient algorithm to determine the optimal ordering policy. Using computational experiments, we assess the effect of substitution and replenishment time uncertainty on the order quantities and the profit as a function of the storage capacity.
Dark matter in the Galactic center

Abstract In addition to boasting the highest density of baryonic matter in our galaxy, the center of the Milky Way is also believed to contain an extremely high density of dark matter particles. While dark matter is expected to be gravitationally subdominant to baryons near the Galactic center, many models allow for the annihilation of dark matter into standard model particles, a phenomenon which could be a significant source of high energy radiation in the Galactic center region. In fact, standard models of the dark matter density distribution and annihilation spectrum predict that dark matter at the Galactic center would (1) produce the brightest flux from dark matter annihilation of any region in the sky, and (2) contribute a significant portion of the total γ-ray luminosity observed within several degrees of the Galactic center by the Fermi/LAT. This makes the effort to understand and differentiate the morphologies and spectral features of dark matter and astrophysical γ-ray emission at the Galactic center potentially rewarding. Here, I will summarize the recent developments in indirect searches for dark matter annihilation at the Galactic center, and discuss several of the difficulties in producing accurate models of the high energy astrophysical emission. Finally, I will comment on current efforts to produce multi-wavelength models which better constrain or indicate a dark matter signal at the Galactic center.
Angular Momentum Transfer in Dynamically Collapsing Gaseous Disks

We investigate the angular momentum transfer in dynamically collapsing gaseous disks by using self-similar solutions for self-gravitating viscous disks. As for the mechanisms of angular momentum transfer, the turbulent viscosity and the gravitational torque are considered. We solved the self-similar equations to examine the effects of the angular momentum transfer in the disks in the runaway collapse phase, when a central core is not yet formed. As a result, the angular momentum transfer makes remarkable differences in rotational velocity distributions as compared with that of the disk with no angular momentum redistribution. In contrast, the distributions of surface density and infall velocity do not vary significantly, since the effect of the centrifugal force is small in this phase. Also, we find that the angular momentum transfer by gravitational torque tends to work more effectively than that due to turbulent viscosity. This is because the magnitude of effective viscosity of gravitational torque is superior to that of turbulent viscosity if the disk is unstable against self-gravity, which is satisfied in the disks in the runaway collapse phase. Finally, we discuss the angular momentum transfer in star-forming disk. From our estimations, we conclude that only a little angular momentum of the disk is transferred in the runaway phase compared with accretion phase before the classical T Tauri star formation. Meanwhile, the first core formation is significantly affected by the angular momentum redistribution in the runaway phase.
Picard–Lefschetz oscillators for the Drinfeld–Lafforgue–Vinberg degeneration for $\operatorname{SL}_{2}$

Let G be a reductive group and let Bun_G denote the moduli stack of G-bundles on a smooth projective curve. We begin the study of the singularities of a canonical compactification of Bun_G due to V. Drinfeld (unpublished), which we refer to as the Drinfeld-Lafforgue-Vinberg compactification. For G=GL_n certain smooth open substacks of this compactification have already appeared in the work of Drinfeld and of L. Lafforgue on the Langlands correspondence for function fields. The Drinfeld-Lafforgue-Vinberg compactification is however already singular for G=SL_2; questions about its singularities arise naturally in the geometric Langlands program, and form the topic of the present article. Drinfeld's definition of the compactification for a general reductive group G relies on the Vinberg semigroup of G, and will be given in [Sch]. In the present paper we focus on the case G=SL_2. In this case the compactification can alternatively be viewed as a canonical one-parameter degeneration of the moduli space of SL_2-bundles. We study the singularities of this degeneration via the weight-monodromy theory of its nearby cycles: We give an explicit description of the nearby cycles sheaf in terms of certain novel perverse sheaves which we call "Picard-Lefschetz oscillators" and which govern the singularities of the degeneration. We then use this description to determine its intersection cohomology sheaf and other invariants of its singularities. We also discuss the relationship of our results for G=SL_2 with the miraculous duality of Drinfeld and Gaitsgory in the geometric Langlands program, as well as two applications of our results to the classical theory: To Drinfeld's and Wang's "strange" invariant bilinear form on the space of automorphic forms; and to the categorification of the Bernstein asymptotics map studied by Bezrukavnikov and Kazhdan as well as by Sakellaridis and Venkatesh.
Relativistic covariance of Ohm's law

The derivation of Lorentz-covariant generalizations of Ohm's law has been a long-term issue in theoretical physics with deep implications for the study of relativistic effects in optical and atomic physics. In this article, we propose an alternative route to this problem, which is motivated by the tremendous progress in first-principles materials physics in general and ab initio electronic structure theory in particular. We start from the most general, Lorentz-covariant first-order response law, which is written in terms of the fundamental response tensor $\chi^\mu_\nu$ relating induced four-currents to external four-potentials. By showing the equivalence of this description to Ohm's law, we prove the validity of Ohm's law in every inertial frame. We further use the universal relation between $\chi^\mu_\nu$ and the microscopic conductivity tensor $\sigma_{k\ell}$ to derive a fully relativistic transformation law for the latter, which includes all effects of anisotropy and relativistic retardation. In the special case of a constant, scalar conductivity, this transformation law can be used to rederive a standard textbook generalization of Ohm's law.
Birational Maps of X(1) into P2

Birational maps of modular curve X (1) attached to SL(2, Z) into the projective plane are studied in the paper. It is shown that every curve of genus 0 and degree q in the projective plain can be uniformized by modular forms for SL(2, Z ) of weight 12q but not with modular forms of smaller weight, and that the corresponding uniformization can be chosen to be a birational equivalence. Other regular maps from X(1) into the projective plane are studied, and the equation of obtained projective curve is computed in the paper. Numerical examples are provided in SAGE.
A comparison of impedance and Lamb wave SHM techniques for monitoring structural integrity of and through welded joints

In this study, the feasibility of monitoring the structural integrity of welded thick aluminum plates was experimentally tested using two widely used SHM methods: impedance and Lamb wave analyses. The test structure was fabricated from two 1/4 inch thick aluminum plates welded together, and various structural defects, such as holes and cuts, were applied. At each of these damage steps, data were collected for both the impedance and Lamb wave techniques. Results consistently revealed the impedance method to be sensitive to damage in and through the weld. The envelopes of the Lamb wave signals were calculated using the S-transformation of the time histories. There was significant change to the curves when different defects were added to the plate. Both of the SHM methods studied detected each of the cuts and holes acting to reduce the overall strength of the structure. Each technique also detected the hole damage on the opposite side of the weld as the sensor(s) used for damage detection. The study further verified that surface waves move across welds allowing SHM methods to detect the defects even if the sensors are located on neighboring plates or geometries.
SlimBox: Lightweight Packet Inspection over Encrypted Traffic

Due to the explosive increase of enterprise network traffic, middleboxes that inspect packets through customized rules have been widely outsourced for cost-saving. Despite promising, redirecting enterprise traffic to remote middleboxes raises privacy concerns about the exposure of corporate secrets. To address this, existing solutions mainly apply searchable encryption (SE) to encrypt traffic and rules, enabling middlebox to perform pattern matching over ciphertexts without learning any sensitive information. However, SE is designed for searching pre-chosen keywords, and may cause extensive costs when applied directly to inspecting traffic in which the keywords cannot be determined in advance. The inefficiency of existing SE-based approaches motivates us to investigate a privacy-preserving and lightweight middlebox. To this end, this paper designs <inline-formula><tex-math notation="LaTeX">$\mathsf{SlimBox}$</tex-math><alternatives><mml:math><mml:mi mathvariant="sans-serif">SlimBox</mml:mi></mml:math><inline-graphic xlink:href="wang-ieq1-3222533.gif"/></alternatives></inline-formula>, which rapidly screens out potentially malicious packets in constant time while incurring only moderate communication overhead. Our main idea is to fragment a traffic/rule string into sub-patterns to achieve conjunctive sub-pattern matching over ciphertexts, while incorporating the position information into the secure matching process to avoid false positives. Experiment results on real datasets show that <inline-formula><tex-math notation="LaTeX">$\mathsf{SlimBox}$</tex-math><alternatives><mml:math><mml:mi mathvariant="sans-serif">SlimBox</mml:mi></mml:math><inline-graphic xlink:href="wang-ieq2-3222533.gif"/></alternatives></inline-formula> can achieve a good tradeoff between matching latency and communication cost compared to prior work.
Dielectric properties of polymer‐liquid composite systems

The dielectric properties of inhomogeneous media constituted by a glassy semicrystalline polymer (polypropylene) impregnated by an aromatic fluid (monodibenzyltoluene) are studied. The measured permittivity is compared to various forms of mixture equations. The closest agreement is obtained with the Lichteneker’s logarithmic mixing expression. The frequency dependence of ionic conductivity in these swollen materials has also been investigated at low electric fields. An attempt is made to interpret these measurements in terms of Niklasson’s [J. Appl. Phys. 62, R1 (1987)] fractal model taking into account the inner topology of the structure of the medium.
Simplified Configuration Design of Anthropomorphic Hand Imitating Specific Human Hand Grasps

How to design an anthropomorphic hand imitating specific human hand grasps with as few actuators as possible is still a challenge. This letter presents a method for obtaining a simplified configuration of anthropomorphic hand imitating specific human hand grasps based on the motion analyses of the human hand. A participation matrix which characterizes a human hand grasp on joint motion level is constructed according to the motion participation of each finger joint. By adding all participation matrices of expected human hand grasps together a total participation matrix can be derived, and through mathematical processing a simplified anthropomorphic hand configuration can be obtained. Following the proposed method, a simplified anthropomorphic hand configuration that imitates six basic human hand grasps was obtained. A series of grasp experiments with the anthropomorphic hand prototype were conducted to validate the grasping capability as well as the proposed simplified configuration design method. This method can help to obtain a reasonably simplified configuration of an anthropomorphic hand when expected human hand grasps are definite.
Global solution to the incompressible Oldroyd-B model in hybrid Besov spaces

This paper is dedicated to the Cauchy problem of the incompressible Oldroyd-B model with general coupling constant $\om\in (0,1)$. It is shown that this set of equations admits a unique global solution in a certain hybrid Besov spaces for small initial data in $\dot{H}^s\cap\dot{B}^{\fr{d}{2}}_{2,1}$ with $-\fr{d}{2} \fr{d}{2}$, this result extends the work by Chen and Miao [Nonlinear Anal. ,{68}(2008), 1928--1939].
Gas in scattering media absorption spectroscopy – from basic studies to biomedical applications

The recently introduced Gas in Scattering Media Absorption Spectroscopy (GASMAS) technique provides novel possibilities for analysis in biophotonics. Free gas in pores or cavities is monitored with narrow‐band laser radiation, which can discern the gas absorptive imprints which are typically several orders of magnitude more narrow than the features of the surrounding tissue through which the diffusely scattered light emerges to the detector. Important gases monitored are oxygen and water vapour. Applications include diagnosis of human sinus cavities and surveillance of neonatal children, but also characterization of food‐stuffs, food packages and pharmaceutical preparations. Non‐biological applications include the study of construction materials such as wood, polystyrene foams and ceramics. For nano‐porous materials, information on the pore sizes can be obtained from observed line broadening. Apart from concentration measurements, the GASMAS technique also allows the study of gas transport and diffusion, and pressure and temperature information can also be obtained.
Beaming, Baryon Loading, and the Synchrotron Self-Compton Component in Gamma-Ray Bursts

We present detailed calculations of nonthermal synchrotron and synchrotron self-Compton (SSC) spectra radiated by blast waves that are energized by interactions with a uniform surrounding medium. Radio, optical, X-ray, and gamma-ray light curves and spectral indices are calculated for a standard parameter set that yields hard GRB spectra during the prompt emission phase. No lateral spreading of the blast wave is assumed. Absence of SSC hardenings in observed GRB X-ray afterglows indicates magnetic field generation toward equipartition as the blast wave evolves. EGRET detections of 100 MeV-GeV photons observed promptly and 90 minutes after GRB 940217 are attributed to nonthermal synchrotron radiation and SSC emission from a decelerating blast wave, respectively. The SSC process will produce prompt TeV emission that could be observed from GRBs with redshifts z ≲ 0.1, provided γ-γ opacity in the source is small. Measurements of the time dependence of the 100 MeV-GeV spectral indices with the planned Gamma-ray Large Area Space Telescope mission will chart the evolution of the SSC component and test the external shock scenario. Transient optical and X-ray emissions from misaligned GRBs are generally much weaker than on-axis emissions produced by dirty and clean fireballs that would themselves not trigger a GRB detector; thus, detection of long-wavelength transients not associated with GRBs will not unambiguously demonstrate GRB beaming.