Miracle-dz/UniFAR-FTUs huggingface dataset:
Multi-Criteria Optimal Design of Parallel Manipulators Based on Natural Frequency

The Stewart manipulator has characteristics of low natural frequency, high cost and large size which make it difficult to obtain optimum performance with high dynamic response. The lowest natural frequency in the total workspace and average of six frequencies at home configuration of Stewart manipulator are introduced as indices to evaluate dynamic stability. Multi-criteria optimal design based on genetic algorithm (GA) was presented synthetically considering the workspace requirement, lowest natural frequency, average frequency and global dimensionally homogeneous Jacobian matrix condition number. An optimal result was obtained through standard GA using penalty function and the Pareto-optimal set was also obtained through parallel selection method.
Solution of 'Solvable model of a spin glass'

Abstract The Sherrmgton-Kirkpatrick model of a spin glass is solved by a mean field technique which is probably exact in the limit of infinite range interactions. At and above T c the solution is identical to that obtained by Sherrington and Kirkpatrick (1975) using the n → O replica method, but below T c the new result exhibits several differences and remains physical down to T = 0.
VLF reflection properties of the normal and disturbed polar ionosphere in northern Greenland

This paper describes long-wave reflection properties of the high-latitude ionosphere, observed under both quiet and highly disturbed conditions. The data were obtained using a short-pulse VLF ionosounder located within the polar cap, in northern Greenland. Under quiet ionospheric conditions, substantial diurnal, day-to-day, seasonal, and solar cycle variations were observed. During polar cap absorption events the VLF reflection properties of the disturbed ionosphere depended greatly on the solar illumination conditions, as well as the magnitude of the incoming energetic particle flux. The use of the steep-incidence VLF reflection data to develop and validate models of the lower ionosphere is discussed; and electron density profiles are given, derived from reflection data obtained during quiet and disturbed conditions.
A singular perturbation approach to sliding mode control in the presence of input delay

Abstract It is well known that arbitrary small delays in the sliding mode control lead to oscillations and the systems may even become unstable for a greater values of the delay. Output feedback sliding mode control of systems with bounded matched disturbances is considered under small time-varying input delay, which is unavoidable in the feedback. The design objective is to achieve ultimate boundedness of the closed-loop system with the bound proportional to the delay and to the disturbance bounds. Sliding mode controller with a high linear gain is proposed, which leads to the closed-loop singularly perturbed system. An LMI-based solution for evaluation of the design parameters and of the resulting ultimate bound is derived by using different Lyapunov-based methods.
A Primer on the Understanding, Use, and Calculation of Confidence Intervals that are Based on Central and Noncentral Distributions

Reform of statistical practice in the social and behavioral sciences requires wider use of confidence intervals (CIs), effect size measures, and meta-analysis. The authors discuss four reasons for promoting use of CIs: They (a) are readily interpretable, (b) are linked to familiar statistical significance tests, (c) can encourage meta-analytic thinking, and (d) give information about precision. The authors discuss calculation of CIs for a basic standardized effect size measure, Cohen’s δ (also known as Cohen’s d), and contrast these with the familiar CIs for original score means. CIs for δ require use of noncentral t distributions, which the authors apply also to statistical power and simple meta-analysis of standardized effect sizes. They provide the ESCI graphical software, which runs under Microsoft Excel, to illustrate the discussion. Wider use of CIs for δ and other effect size measures should help promote highly desirable reform of statistical practice in the social sciences.
A Water Flow-Like Algorithm for the Travelling Salesman Problem

The water flow-like algorithm (WFA) is a relatively new metaheuristic that performs well on the object grouping problem encountered in combinatorial optimization. This paper presents a WFA for solving the travelling salesman problem (TSP) as a graph-based problem. The performance of the WFA on the TSP is evaluated using 23 TSP benchmark datasets and by comparing it with previous algorithms. The experimental results show that the proposed WFA found better solutions in terms of the average solution and the percentage deviation of the average solution from the best-known solution.
Uni-traveling-carrier photodiodes for high-speed detection and broadband sensing

The uni-traveling-carrier photodiode (UTC-PD) is a novel photodiode that utilizes only electrons as the active carriers. This unique feature is the key to realize its excellent high-speed and high-output characteristics simultaneously. To date, a record 3-dB bandwidth (f3dB) of 310 GHz and a very high millimeter (mm)-wave output power of over 17 mW at 120 GHz have been achieved. These superior characteristics are essential for the detection of high-bit-rate optical signal in communications systems and for the generation of high-frequency electro-magnetic waves in measurement and sensing systems. For optical communications, we have realized a photoreceiver operating at up to 160 Gbit/s and an avalanche photodiode with a record f3dB of 40 GHz. For generating mm-/sub-mm-wave signals, we have developed a compact UTC-PD module with a rectangular waveguide output port for operation at up to 325 GHz. We have also fabricated a quasi-optical module for operation at higher frequencies integrating a UTC-PDs and a planar log-periodic antenna. This module can be operated at up to 1.6 THz with a maximum output-power of 2.6 μW at 1.04 THz. The UTC-PD has been used successfully for several applications, such as mm-wave imaging and photonic local signal supply for radio telescopes, demonstrating its feasibility for high-frequency measurement and sensing systems. As a challenge for future high-sensitivity sensing systems, the possibility of UTC-PD modules operating at a very low temperature of 15 K has also been demonstrated.
Studies of inverse-Compton emission in the Crab Nebula and the BL Lac object 1ES 1959+650

This thesis concerns the study of inverse-Compton emission from two astrophysical sources. The first object, 1ES 1959+650, is a nearby active galactic nucleus. This source was observed as part of the VERITAS blazar monitoring programme in the hopes of detecting it in the midst of a dramatic flaring event. Over the course of these monitoring observations which span four years, a significant detection of the source in its low state was accumulated. The spectral energy distribution of this source was analysed from optical to VHE and was modelled with a synchrotron self-Compton model with an additional external Compton component. The parameters obtained cannot be fully explained by first-order Fermi acceleration at parallel shocks, and instead may suggest particle acceleration at oblique subluminal shocks, or that 1ES 1959+650 may consist of an inhomogeneous jet with a fast inner spine and slower-moving outer cocoon. The second source is the famous Crab Nebula, for years considered the standard candle of X-ray to VHE γ-ray astronomy. VERITAS observed the Crab Nebula during the recent flare of the high-energy synchrotron component of the source in March 2013. No enhanced VHE emission was detected, but the observations facilitated the calculation of upper limits on any extra VHE spectral component emerging during the flare. A wealth of archival VHE Crab Nebula data also exists, spanning many years. An extended VHE data set of the source from 2000 to 2013 was compiled from Whipple 10m Telescope and VERITAS observations. This data set was searched for short-term flaring activity, but no evidence of this behaviour was found. A slight decrease in the long-term flux of the nebula was detected in the VERITAS data in 2011. This could possibly be correlated with increasing instability of the aerosol content of the local atmosphere around the VERITAS site.
The information inequality for function spaces given a singular information matrix

In this work we extend the scope of the classical Cram´er-Rao lower bound, or information inequality, from Euclidean to function spaces. In other words we derive a tight lower bound on the autocovariance function of a function estimator. We do this in the context of system identification. Two key elements of system identification are experiment design and model selection. The novel information inequality on function spaces is important for model selection because it allows the user to compare estimators using different model structures. We provide a consistent treatment of the case where the Fisher information matrix is singular. This makes it possible to take into account that in optimal experiment design one tries to mask those parts of the system non-identifiable, which are irrelevant for the application.
Validity and Reliability of the Mathematics Self-Efficacy Questionnaire (MSEQ) on Primary School Students

Mathematics self-efficacy is an important personal attribute and self-belief that can influence students’ learning and performance in the subject, as supported by the Social Cognitive Theory. Literature review has shown that due to the scarcity of research on primary school students’ mathematics self-efficacy, there is a lack of validated instrument to measure this psychological construct in the local school context. This study sets out to fill the literature gap by examining the validity and reliability of the Mathematics Self-Efficacy Questionnaire (MSEQ) (14 items). The contents of the instrument were validated before the instrument was administered to 100 primary students. The sample size was recommended based on a 1:5 subject-item ratio. Findings from the Exploratory Factor Analysis (EFA) suggested that mathematics self-efficacy is a unidimensional construct. It is highly reliable and can be used to gauge primary school students’ mathematics self-efficacy in a Malaysian school setting. The educational implications of this study are discussed in this paper.
Scenario of pinch evolution in a plasma focus discharge

In this paper, the possible evolution of a pinched plasma column is presented from the results of temporally resolved measurements using a magnetic probe, interferometry and neutron diagnostics performed on the plasma focus PF-1000 device with deuterium as the filling gas. Together with the discharge axial current of about 1.5 MA a toroidal current component of the order of 100 kA was estimated in the toroidal, helical and plasmoidal structures formed within the dense plasma column. The mass inside these structures increases due to injection of the plasma from the neighborhood regions with a higher pinching pressure. This injected plasma increases the intensity of the internal magnetic field, probably through turbulent motion and the magnetic dynamo effect. The neutrons from the D–D fusion reaction, produced during the formation and decay of plasmoidal structures and constrictions, are accompanied by changes in the axial component of the magnetic field. Then, the transformation and decay of internal closed currents can contribute to the acceleration of high-energy electrons and ions.
LMI characterization of structural and robust stability

Introduces several stability conditions for a given class of matrices expressed in terms of linear matrix inequalities, being thus simply and efficiently computable. Diagonal and simultaneous stability, both characterized by polytopes of matrices, are addressed. Using this approach a method particularly attractive to test a given matrix for D-stability is proposed. Lyapunov parameter dependent functions are built in order to reduce conservativeness of the stability conditions. The key idea is to relate Hurwitz stability with a positive realness condition.
Broadband Circularly Polarized Stair-Shaped Slot Antenna

Abstract This article is introducing a novel broadband circularly polarized slot antenna fed by a coplanar waveguide, with simple layer geometry. A simple design procedure, made of seven stages, is extended to achieve the required performances. The antenna consists of two linked rectangular slots and two asymmetrical L-shaped slots embedded in opposite corners of stair-shaped ground plane with two conducting rectangles that are added to the ground plane in conjunction with a U-shaped strip. This strip is protruded into the slot from the signal line of the coplanar waveguide. By using the U-shaped patch and two conducting rectangles, two orthogonal electric fields with quadrature phase difference, it is possible to excite a circularly polarized wave. The proposed antenna, with a size of 45 × 45 × 0.8 mm3 is enabled to operate across 1.9 to 4.5 GHz with a fractional impedance bandwidth of 81.25%; for S11 less than –10 dB. The 3-dB axial ratio bandwidth is enclosed by the voltage standing wave ratio ≤ 2 impedance bandwidth, and can be up to 48.2% (2.33 to 3.81 GHz), which is appropriate for wireless local area network (2.4 to 2.484 GHz), digital multimedia broadcasting (2.605 to 2.655 GHz), and worldwide interoperability for microwave access (3.3 to 3.8 GHz) systems. The proposed design has been investigated by the simulated and measured results.
Wire antennas over a lossy half-space

A recently developed technique for approximate but accurate evaluation of the various vector potential components associated with a current element radiating over a lossy ground is used to study the problem of antennas radiating over a lossy ground. A general integral equation for an arbitrarily shaped thin-wire antenna over a lossy half-space is derived, and the method of moments is employed to process this equation numerically. Illustrative numerical results are presented to demonstrate the effect of the lossy half-space on a number of antenna configurations.
A Graphical Method for Assessing the Identification of Linear Structural Equation Models

A graphical method is presented for assessing the state of identifiability of the parameters in a linear structural equation model based on the associated directed graph. We do not restrict attention to recursive models. In the recent literature, methods based on graphical models have been presented as a useful tool for assessing the state of identifiability of the parameters of the model. This article proposes the graphical counterpart of the rank condition of the matrix of structural coefficients, which allows for checking of the identifiability through a simple graphical rule. This approach can be used to develop algorithms.
Robust utility maximization, f-projections, and risk constraints

Finding payoff profiles that maximize the expected utility of an agent under some budget constraint is a key issue in financial mathematics. We characterize optimal contingent claims for an agent who is uncertain about the market model. The dual approach that we use leads to a minimization problem for a certain convex functional over two sets of measures, which we first have to solve. Finally, we incorporate a second constraint that limits the risk that the agent is allowed to take. We will proceed as follows: Chapter 1 Given a convex function f and two sets P and Q of probability measures, we consider the problem of minimizing the robust f -divergence infQ∈Q f(P |Q) over P ∈ P . We show that, if P is closed and Q weakly compact, a minimizer exists within the class P if limx→∞ f(x)/x = ∞. The key step is to prove that a certain relevant subset of P is weakly compact. To this end, we use Young’s inequality in an appropriate Orlicz space. P may be interpreted as the set of martingale measures for some semimartingale. Furthermore, we show that if Q is weakly compact and limx→∞ f(x)/x = 0, then there is a minimizer in a class P̄ of extended martingale measures defined on the predictable σ-field.
Using Algebra Word Problems to Assess Quantitative Ability: Attributes, Strategies, and Errors

Changing goals in mathematics education have encouraged more open-ended problem solving in assessment. However, the use of these less constrained approaches has been limited by a lack of demonstrated relations between the underlying cognitive models and measurement consequences. In order to begin to characterize the cognitive basis for this emerging approach to measurement in a small domain-algebra word problemsdetailed analyses of solutions to 20 problems that had appeared on the Graduate Record Examination General Test were collected from 51 undergraduates. Problems were characterized in terms of their major attributes, and solutions were described by students' strategies and errors. Regression analyses indicated that models including attributes such as the need to apply algebraic concepts, problem complexity, and problem content could account for 37% to 62% of the variance in problem difficulty. Protocol analyses identified four major solution strategies-equation formulation, ratio setup, simulation, a.
Toward the Dynamical Convergence on the Jet Stream in Aquaplanet AGCMs

AbstractSystematic sensitivity of the jet position and intensity to horizontal model resolution is identified in several aquaplanet AGCMs, with the coarser resolution producing a more equatorward eddy-driven jet and a stronger upper-tropospheric jet intensity. As the resolution of the models increases to 50 km or finer, the jet position and intensity show signs of convergence within each model group. The mechanism for this convergence behavior is investigated using a hybrid Eulerian–Lagrangian finite-amplitude wave activity budget developed for the upper-tropospheric absolute vorticity. The results suggest that the poleward shift of the eddy-driven jet with higher resolution can be attributed to the smaller effective diffusivity of the model in the midlatitudes that allows more wave activity to survive the dissipation and to reach the subtropical critical latitude for wave breaking. The enhanced subtropical wave breaking and associated irreversible vorticity mixing act to maintain a more poleward peak of .
The large-sample performance of backwards variable elimination

Prior studies have shown that automated variable selection results in models with substantially inflated estimates of the model R 2, and that a large proportion of selected variables are truly noise variables. These earlier studies used simulated data sets whose sample sizes were at most 100. We used Monte Carlo simulations to examine the large-sample performance of backwards variable elimination. We found that in large samples, backwards variable elimination resulted in estimates of R 2 that were at most marginally biased. However, even in large samples, backwards elimination tended to identify the correct regression model in a minority of the simulated data sets.
Observation of the splitting of degenerate surface plasmon polariton modes in a two-dimensional metallic nanohole array

The authors report the experimental observation of the splitting of the degenerate (0,±1) surface plasmon polariton modes excited in a metallic nanohole array integrated with microfluidic channel for delivery and precise control of the index of refraction of overlaying layer. They use high-resolution wavelength and angle scans for excitation of the surface modes and a polarizer-analyzer pair to suppress the nonresonant transmission. The two resultant modes include an intense, spectrally broad low-energy mode and a weaker, much narrower bandwidth high-energy mode.
A study of gas exchange during the transition from deep winter mixing to spring bloom in the Bay of Biscay measured by continuous observation from a ship of opportunity

Monitoring from ships of opportunity allows a wide range of parameters to be measured, thereby extending the coverage of operational oceanographic studies. Observation of dissolved oxygen using new sensors offers an effective way of monitoring changes in biological production. The limits of the application were tested following the transition from winter storms to the spring bloom (2007). Calculation of dissolved nitrogen enables changes in gas saturation due to physical and biological processes to be separated. By combining these measurements with data from numerical models and Argo floats the critical role of subsurface processes in determining rates of change at the surface can be assessed
A Cooperative Trajectory Optimization Algorithm for Connected Vehicles in Merging Zones

Traffic flow optimization and trajectory guidance in merging zones have significant implications for improving capacity and reducing time consumption. The development of V2X communication provides new insights to solve this problem by tackling the information and releasing trajectories schemes. Therefore, this paper aims to discuss the trajectory management in the merging zone for ACC vehicles. A vehicle dispatching and car-following model is proposed to generate steady traffic flow first. An algorithm framework for consecutive traffic flow is presented with the idea of FIFO rules. Then, a two-step method for an individual vehicle is discussed in detail to compute a trajectory. The first step is to select and determine the priority of the optional gaps. The next step is to verify the options’ feasibility, decide on the target gap, and output the trajectories to merge successfully. Numerical experiments validate that the proposed method guarantees safe driving and provides relatively smooth trajectories to the vehicles. Furthermore, increased capacity and higher velocity are observed in a comparative experiment. The cooperative optimization algorithm could be applied efficiently in practice and benefit from its rapid response and low computation complexity.
Influence of ellipticity of nanorods on both TPA of femtosecond laser pulse and transformation of pulse spectrum

We investigate the femtosecond pulse propagation in medium with nanorods under the conditions of both changing the ellipticity (aspect ratio) of nanorods and dependence of TPA from aspect ratio of nanoparticles. The relation between the width of nanorods absorption spectrum and width of laser pulse spectrum as well as detuning of central frequency of absorption spectrum from carrier frequency of wave packet is taken into account at analyzing the laser pulse propagation. This detuning leads to appearance of phase grating which can essentially influence on the laser pulse propagation and compensate the action of pure amplitude grating caused by nonlinear absorption. We found that under certain conditions the distortion of laser pulse spectrum is really absent despite action of various nonlinearities. The second very important effect consists in substantial shift of maximal intensity in time domain due to spectrum self-modulation because of induced pure amplitude grating. This leads to light slowing-down. It should be emphasized that this effect is similar to spatial motion of maximal laser intensity at infrared optical radiation propagation in clouds.