Miracle-dz/UniFAR-FTUs huggingface dataset:
Geometric -models

A class of nonlinear -models coupled to gravity is defined by identifying the coordinates of spacetime with the components of a set of scalar fields. The obtained theories have purely geometric character, and necessarily possess soliton solutions with topologically non-trivial scalar sectors. In some cases, the corresponding configuration spaces are shown to possess the necessary homotopy structure to admit fermions. The stability problem is considered only in the asymptotic region of the soliton solutions. It is shown how the asymptotic flatness of the soliton metric leads to the compactification of the -model target space. As an illustration, the examples of a cosmic string solution and a monopole solution are considered.
Fundamentals of Semiconductors: Physics and Materials Properties

This book has evolved from lecture courses for postgraduate students and gives an excellent tutorial introduction to the basic physics of semiconductors. Physical models are used to explain the various phenomena and mathematical derivation is kept to a minimum. The liberal use of high quality diagrams greatly enhances the presentation and readability. As might be expected from these authors, the coverage of optical properties is particularly strong and contains valuable discussion of the various spectroscopic techniques. The coverage of band structure, lattice dynamics and defects is also good and includes a very readable account of group theoretical methods. Applications to device physics are, however, deliberately excluded. The treatment of transport and hot-carrier effects is rather sketchy. For example, impact ionization, Monte Carlo methods and Landauer formulae are not mentioned. It is also perhaps surprising that heavy doping and impurity band effects are excluded. The book, however, already extends to 617 pages and omissions are inevitable in a subject as large as this. The authors have tried to be topical wherever possible; for example, an interesting account of the quantum Hall effect is included and semiconducting aspects of the new high temperature superconducting materials are mentioned. There is also a useful section on quantum confinement effects. The interest of the book is increased by the inclusion of a number of short historical reviews by eminent authorities. Postgraduate students or researchers wanting a readable but non-superficial introduction, with many references and suggestions for further reading, should find this book very satisfying. The skilled use of intuitive physical argument by these authors is a very effective and efficient way of teaching the subject. The book is highly recommended.
Seeding undergraduate research experience: From Georgia Tech to KFUPM case study

In this paper, implementation and outcomes of an undergraduate research course are presented. The associated gains and learning outcomes of the course are evaluated and benchmarked with other international undergraduate research experiences. The course was offered to undergraduate students at King Fahd University of Petroleum and Minerals (KFUPM). The research group structure adopts Georgia Tech model. The paper summarizes the course structure, content, and best practices. In addition, the results of undergraduate research experience survey are presented and analyzed. The students reported significant gains in understanding of the research process and significant improvements in writing and oral presentation skills.
Stability and interactions of pulses in simplified Ginzburg-Landau equations

We consider in detail two special types of the parameter-free Ginzburg-Landau equation, viz., the ones that combine the bandwidth-limited linear gain and nonlinear dispersion, or the broadband gain, linear dispersion, and nonlinear losses. The models have applications in nonlinear fiber optics and traveling-wave convection. They have exact solitary-pulse solutions which are subject to a background instability. In the former model, we find that the solitary pulse is much more stable than a "densely packed" multi-pulse array. On the contrary to this, a multi-pulse array in the latter model is destroyed by the instability very slowly. Considering bound states of two pulses, we conclude that they may form a robust bound state in both models. Conditions which allow for formation of the bound states qualitatively differ in the two models.
On Siegel's linearization theorem for fields of prime characteristic

In 1981, Herman and Yoccoz (1983 Generalizations of some theorems of small divisors to non Archimedean fields Geometric Dynamics (Lecture Notes in Mathematics) ed J Palis Jr, pp 408–47 (Berlin: Springer) Proc. Rio de Janeiro, 1981) proved that Siegel's linearization theorem (Siegel C L 1942 Ann. Math. 43 607–12) is true also for non-Archimedean fields. However, the condition in Siegel's theorem is usually not satisfied over fields of prime characteristic. We consider the following open problem from non-Archimedean dynamics. Given an analytic function f defined over a complete, non-trivial valued field of characteristic p > 0, does there exist a convergent power series solution to the Schröder functional equation (2) that conjugates f to its linear part near an indifferent fixed point? We will give both positive and negative answers to this question, one of the problems being the presence of small divisors. When small divisors are present this brings about a problem of a combinatorial nature, where the convergence of the conjugacy is determined in terms of the characteristic of the state space and the powers of the monomials of f, rather than in terms of the diophantine properties of the multiplier, as in the complex case. In the case that small divisors are present, we show that quadratic polynomials are analytically linearizable if p = 2. We find an explicit formula for the coefficients of the conjugacy, and applying a result of Benedetto (2003 Am. J. Math. 125 581–622), we find the exact size of the corresponding Siegel disc and show that there is an indifferent periodic point on the boundary. In the case p > 2 we give a sufficient condition for divergence of the conjugacy for quadratic maps as well as for a certain class of power series containing a quadratic term (corollary 2.1).
Probability prediction of tensile strength with acoustic emission count of a glass fiber reinforced polyamide

The aim of this paper is to develop a probabilistic approach for predicting the tensile strength behavior of a glass fiber reinforced polyamide. In the present study, the reliability of tensile strength is proposed based on the developed mathematical models, in which three factors with three levels are implemented. Glass fiber content, temperature and strain rate are chosen as the main input parameters in this study. The tensile strength is considered as output response which is evaluated through experimental tests. The “Strength-Load” method with Monte Carlo simulation is implemented for computing the tensile strength reliability. The proposed approach leads to predict useful the tensile strength behavior for different parameters. In addition, a sensitivity analysis of some input parameters on the reliability is discussed. This method has been also used to analyze and discuss the influence of the dispersions of the glass fiber content and the temperature of a glass fiber reinforced polyamide.
A new method to detect abrupt change based on approximate entropy

Approximate entropy (ApEn) is valid index which can be used to quantitatively reflect dynamic characteristics and complexity of a time series. The ApEn has been developed to detect an abrupt change in one-dimension time series by sliding a fixed widow, which can be identified with an abrupt dynamic change to some extent, but the sliding ApEn results depend on the window scale, and cannot accurately position the time-instant of an abrupt change. Based on this, a new method is proposed in the present paper, i.e., moving cut data-approximate entropy (MC-ApEn), which can be used to detect an abrupt dynamic change in time series. Tests on model time series indicate that the detection results from the present method show relatively good stability and high accuracy, obviously better than those from the sliding ApEn method and the Mann-Kendall method. The applications in daily precipitation records further verify the validity of the present method.
Dynamic response of constant temperature hot-wire system in turbulence velocity measurements

Analytical solutions have been derived for the first time for temperature fluctuations along a hot wire when it is exposed to turbulent velocity fluctuations of different frequencies and wave numbers. The solutions are used to analyse the dynamic response of the hot wire alone first. The results show that attenuation to the velocity fluctuations exists at high frequencies and depends on the relative end-conduction heat loss from the hot wire to its supports. A simplified circuit for a hot-wire anemometer is then used to analyse the frequency response of the combined hot wire and its anemometer. It is found that even though the frequency response of the anemometer (as that determined from a square wave test) can be very high, the cut-off frequency of the combined system is low, depending on the hot-wire length to diameter ratio, Reynolds numbers, overheat ratio and the hot-wire material used. A preliminary investigation of the spatial resolution of the hot wire to the velocity fluctuations at different wave numbers is also presented.
Cryogenic fluid dynamics

The uses of liquid helium I, liquid helium II and gaseous helium near its critical point in experimental investigations are emerging as an important branch of modern fluid dynamics. This paper is an attempt to review the use of liquid helium in research on stability, transition and turbulence. Emphasis is made on the contributions of W F Vinen to turbulence studies in helium II.
Enhanced sensitivity of a surface acoustic wave gyroscope using a progressive wave

A surface acoustic wave (SAW)-based gyroscope with an 80 MHz central frequency was developed on two different piezoelectric substrates (128° YX LiNbO3 and ST-X quartz). A sensor was developed that contained two SAW oscillators. One oscillator was used as the sensing element and had metallic dots in the cavity between the input and output interdigital transducers (IDTs). The other oscillator was used as a reference element. Two oscillators were formed to extract the Coriolis effect by comparing the oscillation frequencies between these two delay lines, and metallic dots were used to induce a Coriolis force. Three different IDT structures were used to obtain a stable progressive SAW. Coupling of modes modeling was conducted prior to fabrication for determining the optimal device parameters. The device was fabricated and then measured on a rate table in accordance with the results of simulation. When the device was subjected to an angular rotation, the oscillation frequencies of the two oscillators were observed to differ. Depending on the angular velocity, the frequency difference was linearly modulated. The obtained sensitivity was approximately 62.57 Hz deg−1 s−1 at angular rates in the range 0–1000 deg s−1 in the case of the LiNbO3 substrate and single-phase unidirectional transducer and combed electrode structure. The dependence of the device performance on the piezoelectric substrate, IDT structure, and temperatures was also characterized. The developed device has good resistance to mechanical shock and stability to temperature.
The Role of Accessibility to Public Transport and Quality of Walking Environment on Urban Equity: The Case of Santiago de Chile

Most studies of public transport accessibility have focused on proximity to stops, walking distances or time to reach them. This approach ignores other accessibility barriers, such as the quality of the urban environment of these walks. The aim of this research is to analyze both accessibility to public transport stops and the quality of the urban walking environment, exploring fairness issues across the city in terms of these two dimensions. The proposed methodology considers the definition of two indicators: walking accessibility to public transport stops and quality of the walking environment, considering different attributes and dimensions. These indicators are later used to develop a fairness analysis at the local and metropolitan level, using Lorenz curves, Gini coefficient, and Foster-Greer-Thorbecke (FGT) poverty measures. A diagnosis based on these indicators for Santiago de Chile allows us to suggest public policy priorities to improve accessibility to public transport and promote modal shift. The results show that 12 out of 34 municipalities in Santiago are deprived of one or both dimensions, not managing to achieve minimum fairness standards. Moreover, since a correlation between low income and poor access and urban space quality is detected, urban fairness across the city would benefit from centralized urban policies not depending on the budget of each administrative division.
Development of Individualized Mechatronic Products - Rapid Adaptation of Product Properties Due To Individual Customer Demands

Mass Customization in the scope of product development means that a product will be developed (and manufactured later on) those properties exactly meet specific customer wishes and requirements. Likewise the concept of Mass Customization is associated with a lot of problems as well, especially concerning late product changes and the actual process of adapting product design properties to specific customer requirements. Without changing corresponding development processes and methods satisfactory product quality cannot be attained within an appropriate development time. The contribution focuses on suitable product development processes and methods of recording customer wishes as well as the implementation of resulting design requirements in a completely unique product.
A Quantile Regression-Based Approach for Online Probabilistic Prediction of Unstable Groups of Coherent Generators in Power Systems

This paper proposes a novel framework for probabilistic data-driven prediction of unstable groups of coherent generators in interconnected power systems. In contrast to existing techniques in which deterministic classification or forecasting approaches are applied to an offline database, the current study relies on a prediction interval (PI)-based method to tackle prediction uncertainties. First, similarity coefficients (SCs) are considered as internal outputs and calculated for all offline cases. Then, at some generator terminals as selected via a feature selection process, voltage values are measured and used as the input features of the prediction tool. Quantile regression forest is conducted to generate PIs, in which several intervals with certain probabilities are predicted for SCs between any pair of generators. Thereafter, the obtained PIs are used to shape an empirical cumulative distribution function of SCs; a Monte Carlo simulation is then conducted to find a reliable estimate of possible grouping patterns. Finally, a decision-making phase is employed to draw clear distinctions among various parts of the most plausible grouping pattern with respect to a reliability index. This approach can offer power system operators wider flexibility to select a corrective control strategy. The effective performance of the developed approach is demonstrated on several IEEE test systems, followed by a discussion of results.
Braneworld holography in Gauss–Bonnet gravity

We investigate holography on an (n − 1)>-dimensional brane embedded in a background of AdS black holes, in n-dimensional Gauss–Bonnet gravity. We demonstrate that for a critical brane near the AdS boundary, the Friedmann equation corresponds to that of the standard cosmology driven by a CFT dual to the AdS bulk. We show that there is no holographic description for non-critical branes, or when the brane is further away from the AdS boundary. We then derive a Cardy–Verlinde formula for the dual CFT on the critical brane near the boundary. This gives us insight into the remarkable correspondence between Cardy–Verlinde formulae and Friedmann equations in Einstein gravity.
Fe i OSCILLATOR STRENGTHS FOR TRANSITIONS FROM HIGH-LYING EVEN-PARITY LEVELS

New radiative lifetimes, measured to ±5% accuracy, are reported for 31 even-parity levels of Fe i ranging from 45061 cm−1 to 56842 cm−1. These lifetimes have been measured using single-step and two-step time-resolved laser-induced fluorescence on a slow atomic beam of iron atoms. Branching fractions have been attempted for all of these levels, and completed for 20 levels. This set of levels represents an extension of the collaborative work reported in Ruffoni et al. The radiative lifetimes combined with the branching fractions yields new oscillator strengths for 203 lines of Fe i. Utilizing a 1D-LTE model of the solar photosphere, spectral syntheses for a subset of these lines which are unblended in the solar spectrum yields a mean iron abundance of 〈log[ε(Fe)]〉 = 7.45 ± 0.06.
Optimization of Bandwidth and Signal Responses of Optically Pumped Atomic Magnetometers for Biomagnetic Applications

Recently developed ultrasensitive optically pumped atomic magnetometers are promising for biomagnetic measurements such as magnetoencephalograms and magnetocardiograms. The magnetometer's bandwidth and amplitude of signal response are important factors for biomagnetic measurements. These factors depend on various operating parameters such as power density and wavelengths of laser beams. By focusing on the transverse spin relaxation time, we theoretically and experimentally studied the change in the bandwidth and amplitude of the signal response. By considering the effect of the attenuation of a pump beam inside a cell, we showed good agreement between theoretical and experimental results. Furthermore, the magnetometer's integrated performances for the factors were evaluated by changing the power density of the pump beam. Measured data indicated that the bandwidth of signal response depended on the power density of the pump beam and that the bandwidth could be tuned to a desirable frequency range.
Problems with Student Evaluations: Is Assessment the Remedy? * † ‡

In his POD post "Re: Problems with Student Evaluations: Is Assessment the Remedy," EdNuhfer (2002) hit the nail on the head:One of the most encouraging solutions that I see out of this morass . the unending tireddebate over student evaluations ◊) . is the assessment movement. Those who object tosophisticated assessments usually ask, "Why can't we just use grades as measures oflearning? " Doesn't that just echo like "Why can't we just use student ratings of professorsas measures of good teaching? My hope is that, a decade from now, members willlook at our discussions about student ratings in the POD archives and realize just how farpeople can come in ten years if they commit to breaking out of primitive conventions. (e.g., using mere grades as measures of learning). _____________________________________________________
Modeling, Analysis, Force Sensing and Control of Continuum Robots for Minimally Invasive Surgery

This dissertation describes design, modeling and application of continuum robotics for surgical applications, specifically parallel continuum robots (PCRs) and concentric tube manipulators (CTMs). The introduction of robotics into surgical applications has allowed for a greater degree of precision, less invasive access to more remote surgical sites, and user-intuitive interfaces with enhanced vision systems. The most recent developments have been in the space of continuum robots, whose flexible structure create an inherent safety factor when in contact with fragile tissues. The design challenges that exist involve balancing size and strength of the manipulators, controlling the manipulators over long transmission pathways, and incorporating force sensing and feedback from the manipulators to the user. Contributions presented in this work include: (1) prototyping, design, force sensing, and force control investigations of PCRs, and (2) prototyping of a concentric tube manipulator for use in a standard colonoscope. A general kinetostatic model is presented for PCRs along with identification of multiple physical constraints encountered in design and construction. Design considerations and manipulator capabilities are examined in the form of matrix metrics and ellipsoid representations. Finally, force sensing and control are explored and experimental results are provided showing the accuracy of force estimates based on actuation force measurements and control capabilities. An overview of the design requirements, manipulator construction, analysis and experimental results are provided for a CTM used as a tool manipulator in a
Self-consistent calculation of facet heating in asymmetrically coated edge emitting diode lasers

A numerical model is introduced that self-consistently calculates the time dependent axial variations of photon density, carrier density and temperature in semiconductor lasers. The most important approximations are outlined. In order to illustrate the capability of the model, some results are shown for an asymmetrically coated DQW GaAs/GaAlAs edge emitting laser diode. The temperature rise at the facets and the corresponding profiles of carrier and photon density are calculated. The asymmetric behaviour of the profiles is discussed. The heating is calculated as a function of surface recombination velocity at the mirrors and as a function of injection current. The calculations provide insight into the process of facet heating and catastrophic optical damage. The calculations are confirmed by experimental investigations.
Vibration‐based structural condition assessment using convolution neural networks

A novel vibration‐based structural health monitoring (SHM) approach that uses two‐dimensional deep convolution neural networks (CNN) is introduced. The CNN extracts the features from acceleration response histories and drastically reduces the dimension of response history to make damage state classification possible with limited number of acceleration measurements. The proposed method was validated, and its applicability and efficiency were demonstrated using vibration response data recorded during the shake‐table testing of a one‐fourth–scale model of a reinforced concrete highway bridge. The proposed method predicted predefined damage states with 100% accuracy using recorded (acceleration) vibration response data. The method was shown to be robust and sensitive to very small changes in structural condition. It is also noted that the CNN‐based SHM method is scalable to any large number of damage states (including extent and location) with suitable network training. The required training data may be generated analytically using a nonlinear finite element model.