nils-herrmann/clean_scirepeval huggingface dataset:
Finite-difference Green's functions on a 3-D cubic lattice — Integer versus fixed-precision arithmetic recurrence schemes

Time-domain 3-D lattice Green's function (LGF) sequences can be evaluated using a single-lattice point recurrence scheme, and play an important role in finite-difference Green's function diakoptics. Asymptotically, at large distances, the LGFs in three dimensions can be described in terms of six wave constituents, each oscillating with its own instantaneous complex or real frequency. All instantaneous frequencies eventually become real, say at discrete time nAC. We present evidence that indicates that if fixed-precision arithmetic results in a prohibitive loss of accuracy, then that happens before nAC. If a sufficient number of significant digits is used, and loss of accuracy is curtailed before n = nAC, then the recurrence scheme will yield reliable results for a long time after (if not indefinitely). Moreover, the resulting fixed-precision recurrence scheme is still considerably more efficient than the exact scheme based on integer arithmetic.
Analysis of "quasi-modes" in periodic segmented waveguides

A three-dimensional (3-D) explicit finite difference beam propagation method (3-D EFD-BPM) has been used to study the modal characteristics and losses of periodic segmented waveguides (PSWs). Results for the variation of the mode width and depth, as a function of the duty-cycle and period, are presented and compared with those obtained using the equivalent continuous waveguide model at a wavelength of 1.55 /spl mu/m. The radiation losses associated with the modulation of the refractive index are studied and we show that a 3-D representation of a PSW is necessary to evaluate the radiation loss.
Ultra-wideband analogue channels using solitons

It is shown that the dynamics of N-solitons of the Korteweg-de Vries (KdV) equation can be reduced to the Toda lattice equations for the temporal positions of the solitons when the solitons are nearly identical and widely separated in time. Invariants of the KdV equation map to corresponding invariants of the Toda lattice, and the map exists in the limit N/spl rarr//spl infin/. These invariants form analogue channels for the communication of data in which an exact memory of the initial conditions is preserved, even though the KdV wavetrain itself is evolving dynamically. It follows that there exist channels which are immune to the effects of the interpulse dynamics in the KdV wavetrain.
Scattered field analysis of a focused reflector using the Gabor series

A Gabor series representation is used to represent the induced currents in a single reflector illuminated by a plane wave, in order to calculate the received field on the focal plane. The phase-space location property of the modulated Gaussians included in the Gabor series is used to make substantial simplifications in the determination of the scattered field. The physical optics (PO) spectral integral representation of the scattered field is transformed into a multiple sum of beams with well defined parameters; this representation is more suitable for numerical calculation.
Finite-difference Green's function diakoptics — Unlimited stable lookback schemes for non-trivial problems

Earlier, we have analysed a finite-difference timedomain (FDTD) toy problem for a configuration with two disjoint domains, each consisting of a single point, using a Green's function diakoptics unlimited lookback scheme, based on the inverse of the stability function. We have developed an analogous scheme for non-trivial problems involving at least one interior point in one of the domains that occurs in the stability function, but does not enter directly into the boundary operator of the lookback scheme. This scheme preserves the stability. If self-consistency regarding the use of the proper discrete Green's functions is maintained, the boundary operator remains restricted to the boundary. Otherwise the boundary operator fills up to become a domain operator, but may still be usable.
56 nm pitch copper dual-damascene interconnects with triple pitch split metal and double pitch split via

This work demonstrates the building of a 56 nm pitch copper dual damascene interconnects which connects to the local interconnect level. This M1/V0 dual-damascene used a triple pitch split bi-directional M1 and a double pitch split contact (V0) scheme where the local interconnects are with double pitch split in each direction, respectively. This scheme will provide great design flexibility for the advanced logic circuits. The patterning scheme is multiple negative tone development lithography-etch. A memorization layer is utilized in the triple patterned M1 and the double patterned V0 levels, respectively. After transferring the two via levels into the metal memorization layer, a self-aligned-via (SAV) RIE scheme was used to create vias confined by line trenches such that via to line spacing is maximized for better reliability. Seven litho/etch steps (LIP1/LIP2/V0C1/V0C2/M1P1/M1P2/M1P3) were employed to present this revolutionary interconnects.
A time-domain algorithm for the analysis of second-harmonic generation in nonlinear optical structures

A time-domain simulator of integrated optical structures containing second-order nonlinearities is presented. The simulation algorithm is based on nonlinear wave equations representing the propagating fields and is solved using the finite-difference time-domain method. The simulation results for a continuous-wave operation are compared with beam propagation method simulations showing excellent agreement for the particular examples considered. Because the proposed algorithm does not suffer from the inaccuracies associated with the paraxial approximation, it should find application in a wide range of device structures and in the analysis of short-pulse propagation in second-order nonlinear devices.
Band-Edge High-Performance High-k/Metal Gate n-MOSFETs Using Cap Layers Containing Group IIA and IIIB Elements with Gate-First Processing for 45 nm and Beyond

We have fabricated electrically reliable band-edge (BE) high-k/metal nMOSFETs stable to 1000degC, that exhibit the highest mobility (203 cm2/Vs @ 1MV/cm) at the thinnest Tinv (1.4 nm) reported to date. These stacks are formed by capping HfO2 with ultra-thin layers containing strongly electropositive gp. IIA and IIIB elements (e.g. Mg and La), prior to deposition of the TiN/Poly-Si electrode stack, in a conventional gate-first flow. Increasing the cap thickness tunes the Vt/V fb from a midgap position to BE while maintaining high mobility and good PBTI. The addition of La can enhance the effective k value of the dielectric stack, resulting in EOTs < 1nm. Short channel devices with band edge characteristics are demonstrated down to 60 nm. Finally, possible mechanisms to explain the nFET Vt shift are discussed
Robust self-aligned via process for 64nm pitch Dual-Damascene interconnects using pitch split double exposure patterning scheme

A self-aligned via(SAV) process was employed to build 64nm pitch Dual-Damascene(DD) interconnects using a pitch split double exposure pattering scheme to form the Cu lines. TiN hardmask (HM) density and thickness were optimized to achieve the SAV process and DD structure build. We present STEM cross sections of the structures after TiN HM deposition, HM open and DD RIE to determine the minimum required TiN HM thickness for the SAV process. We characterized the TiN loss for each RIE step from cross section results and defined the optimal TiN thickness for 64nm pitch interconnects. Using the optimized TiN thickness, we fabricated DD structures and compared the metal-to-via short electrical performance for SAV and non-SAV processes to show the overlay (OL) impact on shorts yield. Structures fabricated using the SAV process have excellent yield regardless of the degree of via misalignment in the SAV direction since no via CD growth occurs in the constrained SAV direction, while those processed with a non-SAV scheme show via yield degradation with increasing via misalignment. Also, with respect to misalignment in the non-SAV direction, there were no significant electrical differences between structures made using SAV and non-SAV approaches.
Monolithically integrated InGaAs-AlGaInAs Mach-Zehnder Interferometer optical switch using quantum-well intermixing

A highly efficient monolithically integrated Mach-Zehnder interferometer (MZI) optical switch based on a 1.5-/spl mu/m InGaAs-AlGaInAs multiple-quantum-well structure is reported. The device was fabricated by integrating phase shifter sections with bandgap-shifted low-loss waveguides obtained by a single step sputtered SiO/sub 2/-annealing quantum-well intermixing technique. Evaluation of the refractive index change induced by current injection (plasma, band-filling, band-shrinkage effects) and applied electric field (quantum confined Stark effect) based on the MZI was investigated. A device with an active length of 400 /spl mu/m in one of the MZI arms had an extinction ratio /spl ges/20 dB with a half-wavelength current (I/sub /spl pi//) and half-wavelength voltage V/sub /spl pi// as low as 3.2 mA and 3.5 V (1.9 V in push-pull configuration), respectively.
22 nm technology compatible fully functional 0.1 μm2 6T-SRAM cell

We demonstrate 22 nm node technology compatible, fully functional 0.1 mum2 6T-SRAM cell using high-NA immersion lithography and state-of-the-art 300 mm tooling. The cell exhibits a static noise margin (SNM) of 220 mV at Vdd=0.9 V. We also present a 0.09 mum2 cell with SNM of 160 mV at Vdd=0.9 V demonstrating the scalability of the design with the same layout. This is the world's smallest 6T-SRAM cell. Key enablers include band edge high-kappa metal gate stacks, transistors with 25 nm gate lengths, thin spacers, novel co-implants, advanced activation techniques, extremely thin silicide, and damascene copper contacts.
A theoretical model of synchronization of a mode-locked semiconductor laser with an external pulse stream

The frequency range over which a semiconductor laser will synchronize to an external pulse stream is analyzed. The laser is taken to be fully integrated, consisting of an amplifier, a passive waveguide and a saturable absorber. The model is of the lumped parameter type and, in particular, includes the effects of large signal optical pulses, absorption in the passive waveguide and gain dispersion and self-phase modulation in the amplifier. The situation in which the external signal illuminates the saturable absorber without being coupled optically into the laser cavity is analyzed. It is shown that, for synchronization to occur, the external signal must be of comparable intensity to that of the circulating pulse. The range over which locking will occur lies between 0.05% and 0.2% of the mode-locking frequency for external signals of amplitude 0.1 to 0.5 times that of the circulating pulse. It is concluded that integrated mode-locked semiconductor lasers could be used for clock extraction in communication systems.
Discrete spatial solitons

/sup W/e will review our recent experimental results in nonlinear waveguide arrays and discuss the differences between continuous and discrete nonlinear systems. When a discrete soliton is launched in a waveguide array, it resembles in many ways its continuous counterpart. However, since a slab is invariant to translations and rotations, no significant changes are observed when standard spatial solitons are launched at an angle, or in different initial positions. When a discrete soliton is launched with a phase-gradient across the initial distribution, it hops sideward while propagating along the array. The deviation from the continuous case appears particularly at higher powers, where the soliton may lock to the initial waveguides, suppressing the transverse motion. The previous situation can be reversed by launching a straight beam in an arbitrary position of the array. An asymmetric distribution of power in adjacent waveguides can generate a nonlinear phase gradient and therefore, induce power dependent steering of the discrete soliton. We will present experimental results showing how significant steering of a "discrete" spatial soliton beam can be obtained through a much smaller "control" of the input beam parameters.
FDTD simulation of the nonlinear gain and pumping dynamics of optically pumped VCSELs

In this paper we apply the method of the FDTD solution of the full-wave vectorial Maxwell-Bloch equations for a two-level quantum system to investigate the nonlinear gain spatio-temporal dynamics of an active semiconductor microcavity. We have performed a number of validation studies in order to establish the ability of our 1D semiclassical model to correctly recover the nonlinear gain dynamics of a homogeneously broadened two-level saturable gain medium.
A Unified Approach for EIT Imaging of Regional Overdistension and Atelectasis in Acute Lung Injury

Patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) are vulnerable to ventilator-induced lung injury. Although this syndrome affects the lung heterogeneously, mechanical ventilation is not guided by regional indicators of potential lung injury. We used electrical impedance tomography (EIT) to estimate the extent of regional lung overdistension and atelectasis during mechanical ventilation. Techniques for tidal breath detection, lung identification, and regional compliance estimation were combined with the Graz consensus on EIT lung imaging (GREIT) algorithm. Nine ALI/ARDS patients were monitored during stepwise increases and decreases in airway pressure. Our method detected individual breaths with 96.0% sensitivity and 97.6% specificity. The duration and volume of tidal breaths erred on average by 0.2 s and 5%, respectively. Respiratory system compliance from EIT and ventilator measurements had a correlation coefficient of 0.80. Stepwise increases in pressure could reverse atelectasis in 17% of the lung. At the highest pressures, 73% of the lung became overdistended. During stepwise decreases in pressure, previously-atelectatic regions remained open at sub-baseline pressures. We recommend that the proposed approach be used in collaborative research of EIT-guided ventilation strategies for ALI/ARDS.
High reliability 32 nm Cu/ULK BEOL based on PVD CuMn seed, and its extendibility

A 32 nm BEOL with PVD CuMn seedlayer and conventional PVD-TaN/Ta liner was fully characterized by fundamental, integrated, and reliability methods. CuMn was confirmed to have fundamental advantages over CuAl, such as higher electromigration (EM) reliability for the same Cu line resistance (R). Both low R and high reliability (EM, SM, and TDDB) were achieved. Improved extendibility of CuMn relative to CuAl was also supported by studies of alloy interactions with advanced liner materials Ru and Co, and by enhancement of ultra-thin TaN barrier performance.
The lossless compression of AVIRIS images by vector quantization

The structure of hyperspectral images reveals spectral responses that would seem ideal candidates for compression by vector quantization. This paper outlines the results of an investigation of lossless vector quantization of 224-band Airborne/Visible Infrared imaging Spectrometer (AVIRIS) images. Various vector formation techniques are identified and suitable quantization parameters are investigated. A new technique, mean-normalized vector quantization (M-NVQ), is proposed which produces compression performances approaching the theoretical minimum compressed image entropy of 5 bits/pixel. Images are compressed from original image entropies of between 8.28 and 10.89 bits/pixel to between 4.83 and 5.90 bits/pixel.
Interleaving two-dimensional lattices to create three-dimensional photonic bandgap structures : Photonic crystals and microstructures

A two-dimensional lattice consists of an inhomogeneous dielectric medium which has periodic variations of permittivity along two linear directions, and is uniform in the third dimension. The paper considers a class of three-dimensional photonic bandgap materials formed by the interleaving of a pair of two-dimensional lattices whose uniform directions are mutually orthogonal, the so-called 'woodpile' geometry. It is shown by numerical calculations that the strong polarisation discrimination exhibited by the constituent two-dimensional sublattices in their respective stopbands leads to a completeiy three-dimensional photonic bandgap crystal in all polarisations when the two sublattices are interleaved. For a general class of such synthetic crystals having arbitrary two-dimensional distributions in the sublattices, many properties of the three-dimensional interleaved crystal can be predicted directly from a knowledge of the properties of the sublattices, thereby radically reducing the computational cost of their determination.
Analysis of dynamics of monolithic passively mode-locked laser diodes under external periodic excitation

A distributed time-domain model is used for numerical analysis of the dynamics of a passively mode-locked laser diode under external modulation at a frequency close to the round-trip frequency of the laser. Dynamical regimes of the laser, such as synchronisation locking, quasilocking and RF frequency mixing, are studied. For the locked regime, steady-state parameters are defined, the crucial role of group-velocity dispersion in achieving locking is demonstrated and stages of the locking dynamics and corresponding time constants are identified.
Joint spatio-temporal registration and microvasculature segmentation of retinal angiogram sequences

We discuss the problem of 2D+t intra- and inter-sequential registration of retinal angiograms. A joint spatio-temporal registration algorithm is presented based on a RANSAC (RANdom SAmple Consensus) approach incorporating a quadratic model to describe “pairwise” image homography. This is incorporated into a local-to-global hierarchical joint registration framework. After registration, vessel centrelines are segmented to subpixel accuracy by applying multi-scale steerable complex wavelet filters. Frame-by-frame microvascular centrelines in Regions-of-Interest (ROIs) are evaluated against segmented centrelines of the temporal average of the registered sequences. The microvascular centrelines in registered sequences can be compared intra-sequentially and inter-sequentially, allowing non-invasive clinical monitoring of micro-circulation. This has the potential to detect the presence of microemboli and pathological structural alterations.
Self-Learning Scene-Specific Pedestrian Detectors Using a Progressive Latent Model

In this paper, a self-learning approach is proposed towards solving scene-specific pedestrian detection problem without any human annotation involved. The self-learning approach is deployed as progressive steps of object discovery, object enforcement, and label propagation. In the learning procedure, object locations in each frame are treated as latent variables that are solved with a progressive latent model (PLM). Compared with conventional latent models, the proposed PLM incorporates a spatial regularization term to reduce ambiguities in object proposals and to enforce object localization, and also a graph-based label propagation to discover harder instances in adjacent frames. With the difference of convex (DC) objective functions, PLM can be efficiently optimized with a concave-convex programming and thus guaranteeing the stability of self-learning. Extensive experiments demonstrate that even without annotation the proposed self-learning approach outperforms weakly supervised learning approaches, while achieving comparable performance with transfer learning and fully supervised approaches.
Multi-temporal foreground detection in videos

A common task in video processing is the binary separation of a video's content into either background or moving foreground. However, many situations require a foreground analysis with a finer temporal granularity, in particular for objects or people which remain immobile for a certain period of time. We propose an efficient method which detects foreground at different timescales, by exploiting the desirable theoretical and practical properties of Robust Principal Component Analysis. Our algorithm can be used in a variety of scenarios such as detecting people who have fallen in a video, or analysing the fluidity of road traffic, while avoiding costly computations needed for nearest neighbours searches or optical flow analysis. Finally, our algorithm has the useful ability to perform motion analysis without explicitly requiring computationally expensive motion estimation.
Statistical Characterization of Protein Ensembles

When accounting for structural fluctuations or measurement errors, a single rigid structure may not be sufficient to represent a protein. One approach to solve this problem is to represent the possible conformations as a discrete set of observed conformations, an ensemble. In this work, we follow a different richer approach and introduce a framework for estimating probability density functions in very high dimensions and then apply it to represent ensembles of folded proteins. This proposed approach combines techniques such as kernel density estimation, maximum likelihood, cross validation, and bootstrapping. We present the underlying theoretical and computational framework and apply it to artificial data and protein ensembles obtained from molecular dynamics simulations. We compare the results with those obtained experimentally, illustrating the potential and advantages of this representation.
Missile tracking using knowledge-based adaptive thresholding

We apply a knowledge-based segmentation method developed for still and video images to the problem of tracking missiles and high speed projectiles. Since we are only interested in segmenting a portion of the missile (namely, the nose cone), we use our segmentation procedure as a method of adapting thresholding. The key idea is to utilize a priori knowledge about the objects present in the image, e.g. missile and background, introduced via Bayes' rule. Posterior probabilities obtained in this way are anisotropically smoothed, and the image segmentation is obtained via MAP classifications of the smoothed data. When segmenting sequences of images, the smoothed posterior probabilities of past frames are used as prior distributions in succeeding frames.
Vector-valued active contours

A framework for object segmentation in vector-valued images is presented in this paper. The first scheme proposed is based on geometric active contours moving towards the objects to be detected in the vector-valued image. Objects boundaries are obtained as geodesics or minimal weighted distance curves in a Riemannian space. The metric in this space is given by a definition of edges in vector-valued images. The curve flow corresponding to the proposed active contours holds formal existence, uniqueness, stability, and correctness results. The technique is applicable for example to color and texture images. The scheme automatically handles changes in the deforming curve topology. We conclude the paper presenting an extension of the color active contours which leads to a possible image flow for vector-valued image segmentation. The algorithm is based on moving each one of the image level-sets according to the proposed color active contours. This extension also shows the relation of the color geodesic active contours with a number of partial-differential-equations based image processing algorithms as anisotropic diffusion and shock filters.