Miracle-dz/UniFAR-FTUs huggingface dataset:
Terahertz generation in submicron GaN diodes within the limited space-charge accumulation regime

The conditions for microwave power generation with hot-electron transport are investigated in a submicron GaN diode when it operates in the limited space-charge accumulation (LSA) mode. Applying a transport model based on the local quasistatic approximation, the analysis shows that the nitride diodes can support the LSA mode of oscillation in the terahertz-frequency range. For a 100nm n-GaN diode with a cross section of 500μm2 and the electron density of 1×1017cm−3, the generated microwave power is estimated to be as high as ≈0.6W with the corresponding dc-to-rf conversion efficiency of ≈9% and the negative differential resistance of ≈−1. 3Ω; which thus provides an efficient mechanism to achieve very high-frequency microwave generation in the nitrides.
Deep QL-APF: An Automated Playtesting Framework for Unreal Engine

We introduce an approach to automate part of the playtesting process in games made with Unreal Engine 4, with the objective of speeding up and reducing the costs associated with manual playtest-ing. We use the Unreal Automation System to integrate the Deep QL-APF framework with the Unreal Engine in order to perform automated gameplay tests. We propose a Deep Q-Learning method for the agent to travel to a destination and achieve a well-defined game objective by trial and error, using feedback from its own actions and experiences. To validate the solution we use a single case study provided by Funcom ZPX 1 . Three experimental procedures were executed to assess the approach. We obtained results regarding two different agents learning performance and a visual representation of the path they performed. One agent is responsible for reaching the goal as quickly as possible while the other wants to reach the goal while moving close to the map constituents. The agents can also identify problems in the game environment while they explore it. From the results we confirm that Reinforcement Learning agents are capable of learning how to achieve a game objective and find problematic areas in a Unreal Engine environment. We also found that the agents performed the behaviours we wanted them to, but, crafting different agents to perform the same test and achieve the same game objective with different behaviours was complex and hard to come up with for us. We compared the problems found by agents with the ones found during manual playtesting and concluded that these automated agents can replace human testers when performing these type of exploratory test.
The Interstellar Medium around Galactic WN Stars: WR 2, WR 128, and WR 151

The neutral hydrogen distribution has been studied in the direction of three Galactic Wolf-Rayet (W-R) stars, using the 100 m Effelsberg radio telescope. Neutral hydrogen voids, regions of low H I emissivity, are observed over a 10–16 km s-1 velocity range for the stars WR 2 (=HD 6327), WR 128 (=HD 187282), and WR 151 (=CX Cep). These minima are interpreted as the observable 21 cm counterpart of the interstellar bubble created by the powerful winds of W-R stars and their progenitors. The H I cavities are elongated structures having an axial ratio ranging from 1.3 (WR 151) to 2.0 (WR 128). As pointed out in previous studies, the W-R stars are always off-center with respect to either the geometric center of the H I void or the absolute minimum inside the cavity. This offset ranges from 40% to 70% of the H I hole's minor axis. The major axes of these cavities are ∼30 pc for both WR 2 and WR 128, and ∼50 pc for WR 151. The missing H I mass amounts to 96 M⊙ (WR 128), 200 M⊙ (WR 2), and 480 M⊙ (WR 151). Some of the physical parameters of the ring nebula associated with WR 128, such as its expansion velocity, 80 ± 22 km s-1, radius, 6.3 ± 0.2 pc, and characteristic age, (7.4 ± 2.4) × 104 yr, are derived from a simple geometric model that accounts for the discrepancy between the radial velocity of the H I hole and the ring nebula related to WR 128.
A quantitative evaluation of diffusion-weighted MR imaging of focal hepatic lesions by using an optimal b-value for differentiation of malignant and benign tumors

In this study, we aimed to determine an optimized b-value for the characterization of focal hepatic lesions (malignant and benign tumors) and to perform a quantitative analysis of the results. To achieve this, we obtained diffusion-weighted images (DWIs) from 30 focal hepatic disease patients (liver metastasis: 20 patients, and liver hemangioma: 10 patients) by using a 1.5 T MR system and varying the b-value from 0 through 200. The experimental results revealed that at a b-value of 50, the DWIs of the lesions showed high signal-to-noise ratios (SNRs; SN Rliver_meta. = 229.83 ± 19.08, SNRliver_hema. = 241.66 ± 29.02), high contrast-to-noise ratios (CNRs; CN Rliver_meta. = 39.66 ± 3.87, C N Rliver_hema. = 142.55 ± 12.97) and low signal intensities of the apparent diffusion coefficients (ADCs; ADCliver_meta. = 1.40 × 10−3 ± 0.29, ADCliver_hema. = 2.55 × 10−3 ± 0.92). The focal hepatic lesions were clearly depicted, with DW images and ADC maps corresponding well. Thus, we could present an optimized b-value (b = 50) for the characterization of focal hepatic lesions. Additionally, the ADC values of liver lesions were found to be useful in differentiating benign from malignant tumors.
Crop classification using MODIS EVI series in North China

We studied the crop classification in North China using multi-bands MODIS data with time resolution of 8 days and spatial resolution of 500m in year 2007. Vegetation Index EVI was seen as a robust vegetation indicator and its layers were stacked in the time dimension to detect the phenology of various vegetation types including our targets crops. Before classification, a series of data processing steps were performed: first, a comprehensive use of time-frequency analysis methods such as iterated Savitzky-Golay filtering, multi-resolution analysis and energy threshold based algorithm was conducted to reduce noises in the EVI series data; second, crop/non-crop boundary was obtained from the noise reduced data using a binary encoding based algorithm, in which we introduced the concept of "effective width" as the threshold for crop/non-crop vegetation; third, we analyzed the wave structures including starting/ending/maximum curvature/minimum curvature/half wave height points and matched them to the typical crops' phenology in North China to form the training sample sets. The classification methods include ISODATA (unsupervised), SAM (Spectral Angle Mapper), Minimum Distance and SVM (Support Vector Machine). The results showed that the SVM method had the highest accuracy: 82.3% in the double-cropping area and 93.4% in the single-cropping area.
Smart structures using shape memory alloys

Elevated civil structure systems, such as communication towers and water tanks, are prone to higher mode vibration and earthquake induced damages. To mitigate damages, however, the structures are retrofitted with conventional (e.g. steel casing) and/or emerging techniques (e.g. smart structures). Smart structure entails integration of system behavior, control design and actuators. In this paper, utility of smart structures is illustrated through an elevated water tank concrete column. The concrete column is modeled as a continuous system, using the Lagrangian formulation, and linear quadratic regulator (LQR) is used for the control system, and shape memory alloy (SMA) for actuation. The water tank is excited with the 1940 El-Centro earthquake record. A sensitivity analysis is performed on the controller error and penalizing constants, as well as actuator location and angle of the connection. The four control variables that can be analyzed for the controller are: Rr, Qr, Re, and Qe, which are the control penalty, error penalty, measurement noise and process noise, respectively. The connection height on the beam and angle of the actuator is also analyzed for optimal performance. From the sensitivity analysis, the most efficient controller configuration is identified for further analysis of the structure. Optimal actuator configuration can be found based on the reduction of displacement versus the amount of energy used. It has been shown that using the SMA, the seismic demand on the concrete column is reduced using the SMA.
Lower bounds on the minimum hamming distance achievable with runlengh constrained or DC free block codes and the synthesis of a (16,8) D min = 4 DC free block code

Error correction coding gain can be obtained with dc free magnetic recording codes having a minimum Hamming distance d_{\min}\geq 4 . In this information theoretic paper we establish lower bounds on the minimum Hamming distance achievable with (2n,k) (ie R = k/2n) block codes with runlength constrained or dc free sequences, and present a table with the computed guaranteed minimum values of k for (2n,k) dc free block codes with (b=0, l=2n-1, C=n) sequences, a specified block length 2n and desired minimum Hamming distance d_{\min} . Subsequently, we present the formal synthesis of a (16,8) d_{\min}=4 code with sequences which have, in NRZ notation, a minimum runlength of 1 and maximum runlength of 8, while the bound on the maximum instantaneous accumulated charge is C = 5. This accumulated charge returns to zero at the end of each 16 bit code word. Encoding and decoding schemes for the synthesized code are also proposed.
Ion heating within the ramp of quasi-perpendicular subcritical collisionless shocks

The heating of the bulk of the incident ions at low Mach number quasi-perpendicular collisionless shocks is observed to take place very rapidly, within the shock ramp. In this paper we show that the trajectories of ions passing through the shock ramp lead to a dispersion in phase space resulting in an effective increase in ion temperature. The main heating is predicted to take place in the second half of the ramp. We present results of self-consistent computer simulations which confirm this prediction.
I-cloth

We present an incremental collision handling algorithm for GPU-based interactive cloth simulation. Our approach exploits the spatial and temporal coherence between successive iterations of an optimization-based solver for collision response computation. We present an incremental continuous collision detection algorithm that keeps track of deforming vertices and combine it with spatial hashing. We use a non-linear GPU-based impact zone solver to resolve the penetrations. We combine our collision handling algorithm with implicit integration to use large time steps. Our overall algorithm, I-Cloth, can simulate complex cloth deformation with a few hundred thousand vertices at 2 - 8 frames per second on a commodity GPU. We highlight its performance on different benchmarks and observe up to 7 - 10X speedup over prior algorithms.
Communication-efficient Conformal Prediction for Distributed Datasets

Coresets have been proven useful in accelerating the computation of inductive conformal predictors (ICP) when the training data becomes large in size. This work shows that coreset-based conformal predictors are not only computationally efficient in the centralised setting, but may also naturally be used in scenarios where the dataset of interest is inherently distributed over at least two machines. This work follows the line of research started in Riquelme-Granada et al. (2019) and Riquelme-Granada et al. (2020b), where ICP is accelerated by using the idea of data com-pression. That is, instead of manipulating the classic conformal algorithm (Vovk et al. (2005)) to gain some computational acceleration, the idea is to use the ICP method as is , on a small dataset that acts as a proxy to the original dataset of interest. This proxy dataset is called a coreset (or core-set) (Feldman et al. (2013)), and it provably correctly approximates the original much-larger dataset, in a well-defined sense, with respect to a machine learning problem. The combination of the coreset technique with that of ICP is known as Coreset-based Inductive Conformal Prediction (C-ICP), and it was shown that it may save a large amount of computing time while retaining the validity and efficiency of ICP (see experiments results in Riquelme-Granada et al. (2019)).
Effective permeability tensor of partially magnetized two-component metaferrites

Expressions for the effective permeability tensor of two-component partially magnetized ferrite-like metamaterials are obtained in the microwave frequency range. The formulas are based on the theory of partially saturated conventional ferrites and the effective medium theory (EMT) of metamaterials presented in a form of an infinite host dielectric medium with periodically embedded ferric cylindrical and spherical inclusions partially magnetized with an external bias DC magnetic field. The low-field losses absence conditions are obtained for the metamaterials under the assumption of a low phenomenological loss term and losses are estimated.
Fragmentation of elongated cylindrical clouds. VI: Comparison with observations

A comparison of hydrodynamical simulations of the collapse and fragmentation of elongated clouds with observations of molecular cores, star formation regions, and binary and multiple systems is presented. Observations of molecular cloud cores suggest appropriate initial conditions for numerical simulations of star formation. They include an elongated structure with rotation about an arbitrary axis and low values of β, the ratio of the absolute value of rotational to gravitational energies. The environments of young stellar objects display warped disks, and bridges of matter between young binaries, both of which are formed in our simulations
Bootstrap prediction bands for forecast paths from vector autoregressive models

The problem of forecasting from vector autoregressive models has attracted considerable attention in the literature. The most popular non-Bayesian approaches use either asymptotic approximations or bootstrapping to evaluate the uncertainty associated with the forecast. The practice in the empirical literature has been to assess the uncertainty of multi‐step forecasts by connecting the intervals constructed for individual forecast periods. This paper proposes a bootstrap method of constructing prediction bands for forecast paths. The bands are constructed from forecast paths obtained in bootstrap replications using an optimization procedure to find the envelope of the most concentrated paths. From extensive Monte Carlo study, it is found that the proposed method provides more accurate assessment of predictive uncertainty from the vector autoregressive model than its competitors. Copyright (C) 2010 John Wiley & Sons, Ltd.
Bayesian Doublespeak∗

Why does misinformation persist, and how does it distort the long-run beliefs and actions of rational agents? Suppose receivers see an infinite stream of messages from a sender of unknown type who observes private signals about an unknown state of the world. We characterize the conditions for “doublespeak” equilibria where one sender type repeatedly reveals each private signal truthfully but another sender type repeatedly fabricates false values of her private signals. Receivers only partially learn the true state in the long run irrespective of the true sender type, resulting in long-run disagreement and ex post incorrect actions by some receivers. Equilibrium fact-checking by receivers does not induce more truth-telling among sender types but reputational concerns can. Our results cast doubt on the presumption that rational agents can pierce through persistent extreme lies in the long run and highlight the deleterious effects of such lies for receiver welfare.
Magnetic configurations in 160-520-nm-diameter ferromagnetic rings

Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA~Received 29 August 2003; revised manuscript received 24 November 2003; published 21 April 2004! The remanent states and hysteretic behavior of thin-ﬁlm magnetic rings has been investigated experimentallyand by micromagnetic modeling. Rings of diameters 160–520 nm, made from Co using lift-off processing,show three distinct remanent states: a vortex state, an ‘‘onion’’ state with two head-on walls, and a ‘‘twisted’’state containing a 360° wall. The range of stability of these states varies with ring geometry, with smaller widthrings showing higher switching ﬁelds and greater variability.DOI: 10.1103/PhysRevB.69. 144421 PACS number~s! : 75.75. 1a, 75.60. 2d, 85.75. 2dI. INTRODUCTION
Markov decision processes for infinite horizon problems solved with the cosine simplex method

This article presents a new method of linear programming (LP) for solving Markov decision processes (MDPs) based on the simplex method (SM). SM has shown to be the most efficient method in many practical problems; unfortunately, classical SM has an exponential complexity. Therefore, new SMs have emerged for obtaining optimal solutions in the most efficient way. The cosine simplex method (CSM) is one of them. CSM is based on the Karush Kuhn Tucker conditions, and is able to efficiently solve general LP problems. This work presents a new method named the Markov Cosine Simplex Method (MCSM) for solving MDP problems, which is an extension of CSM. In this article, the efficiency of MCSM is compared to the traditional revised simplex method (RSM); experimental results show that MCSM is far more efficient than RSM.
JET IMPINGEMENT ONTO A HOLE WITH CONSTANT WALL TEMPERATURE

Jet impingement onto a hole finds application in process industries. In the present study, a jet impingement onto a hole with a constant wall temperature is examined. The governing flow and heat transfer equations are solved numerically using a control-volume approach. The Reynolds stress turbulence model (RSTM) is employed to account for the turbulence. In the simulations, four hole wall temperatures and two jet velocities are considered. The Nusselt number ratio (ratio of the Nusselt number predicted to the Nusselt number obtained for a fully developed turbulent flow based on the hole entrance Reynolds number) is computed and the mass flow ratio (ratio of mass flow rate through the hole to mass flow emanating from the nozzle) is determined. It is found that increasing hole wall temperature extends the stagnation region close to the top edge of the hole. This, in turn, results in hot gas opposing the impinging jet. Therefore, the mass flow ratio falls with increasing hole wall temperature. The Nusselt number ratio improves at the hole inlet and falls as the axial distance along the hole wall increases toward the hole exit. A Nusselt number ratio of greater than 1 resulted for all the situations employed in the present study.
Continuous complex-valued back-propagation learning

A novel back-propagation learning method is proposed for fully complex-valued layered neural networks. Nonlinearity suitable for realising smooth and unified complex learning is introduced. A gradient descent method is also analysed and optimised so that the variations of independent elements of the output complex vectors are related directly to the fragmentary changes of weighting matrix elements. The learning process is presented and demonstrated.
Finite-length Analysis on Tail probability for Markov Chain and Application to Simple Hypothesis Testing

Using terminologies of information geometry, we derive upper and lower bounds of the tail probability of the sample mean. Employing these bounds, we obtain upper and lower bounds of the minimum error probability of the 2nd kind of error under the exponential constraint for the error probability of the 1st kind of error in a simple hypothesis testing for a finite-length Markov chain, which yields the Hoeffding type bound. For these derivations, we derive upper and lower bounds of cumulant generating function for Markov chain. As a byproduct, we obtain another simple proof of central limit theorem for Markov chain.
Correspondence between the low- and high-frequency limits for anisotropic parameters in a layered medium

Wave propagation in a layered medium when the wavelength is much greater than each layer thickness low frequencyproducesaresponseequivalenttothatofwavepropagation in an equivalent single-layer medium. This equivalent medium is transversely isotropic with symmetry about a vertical axis VTI, and the elastic parameters are computed with the Backus averaging technique. Conversely, when the wavelength is comparable to each layer thickness high frequency, the directional dependence of the phase velocity in the transmission response also can be simulated by replacing thelayeredmediumwithasinglehomogeneousmediumwith properties derived from a time average. It then can be treated approximatelyasaVTImedium.Tocomputethemediumparameters,amethodbasedonfittingthetraveltimeparameters is used.We investigated the relationship betweenThomsen’s anisotropic parameters and computed for the equivalent medium in the low-frequency limit and for the homogenized medium in the high-frequency limit. In our experiments, we used a medium in which layers of only two isotropic materials alternate repeatedly. For the high-frequency limit, we obtainedsolutionsforPP-andSS-wavepropagation.
On the statistical analysis of capture experiments

SUMMARY A procedure is given for estimating the size of a closed population in the presence of heterogeneous capture probabilities using capture-recapture data when it is possible to model the capture probabilities of individuals in the population using covariates. The results include the estimation of the parameters associated with the model of the capture probabilities and the use of these estimated capture probabilities to estimate the population size. Confidence intervals for the population size using both the asymptotic normality of the estimator and a bootstrap procedure for small samples are given.
A geometrically based flattening method for three-dimensional to two-dimensional bra pattern conversion

This article proposes a robust algorithm for three-dimensional (3D) surface reconstruction of a bra fitted to an underlying mannequin via scanned polylines and a novel approach for bra pattern flattening based on linear least squares optimisation. This pattern flattening method projects a patch from the current viewing direction to a two-dimensional (2D) plane, with an orientation into 3D space by mesh reconstruction. The intersection of polylines is checked and a patch adjacency graph is built to form a closed patch surface, which is fitted to a mannequin. The conformity between the 3D bra patch and the 2D projection shows shape preservation when the 3D bra is flattened to 2D patterns using the proposed method. The preservations of shape entities include boundary coordinate preservation, mean value coordinate preservation, edge length preservation and adjacent surface flattening. An algorithm for calculating the local projection plane, which is used for the calculation of best fit mean value coordinate for local surface flattening, is also provided.
Robust single-mode operation in 50&mgr;m ytterbium-doped leakage channel fibers

Leakage channel fibers, where several air holes form a core, can be precisely engineered to create large leakage loss for higher order modes, while maintain negligible transmission loss for the fundamental mode. This unique property can be used for designing optical fibers with large effective mode area, which supports robust fundamental mode propagation. The large air holes in the design also enable the optical fibers to be bend-resistant. The principles of design and operation regime are outlined in this paper. Performance of an ytterbium-doped double clad leakage channel fiber and an ytterbium-doped polarization-maintaining (PM) double clad leakage channel fiber with ~50&mgr;m core diameter is also discussed.