Miracle-dz/UniFAR-FTUs huggingface dataset:
Superimposed Bragg gratings in high-birefringence fibre optics: three-parameter simultaneous measurements

We used a pair of Bragg gratings written in high birefringence fibre optics to measure, simultaneously, longitudinal and transverse strain and temperature. The Bragg gratings are superimposed in the same position of the fibre optic, so as to behave as a punctual sensor. The sensitivity of the spectral response of the device to longitudinal strain, transverse strain and temperature are all characterized, and the results of its application as a three-parameter sensor are also presented.
Genetic algorithm based deliverable segments optimization for static intensity-modulated radiotherapy

The static delivery technique (also called step-and-shoot technique) has been widely used in intensity-modulated radiotherapy (IMRT) because of the simple delivery and easy quality assurance. Conventional static IMRT consists of two steps: first to calculate the intensity-modulated beam profiles using an inverse planning algorithm, and then to translate these profiles into a series of uniform segments using a leaf-sequencing tool. In order to simplify the procedure and shorten the treatment time of the static mode, an efficient technique, called genetic algorithm based deliverable segments optimization (GADSO), is developed in our work, which combines these two steps into one. Taking the pre-defined beams and the total number of segments per treatment as input, the number of segments for each beam, the segment shapes and weights are determined automatically. A group of interim modulated beam profiles quickly calculated using a conjugate gradient (CG) method are used to determine the segment number for each beam and to initialize segment shapes. A modified genetic algorithm based on a two-dimensional binary coding scheme is used to optimize the segment shapes, and a CG method is used to optimize the segment weights. The physical characters of a multileaf collimator, such as the leaves interdigitation limitation and leaves maximum over-travel distance, are incorporated into the optimization. The algorithm is applied to some examples and the results demonstrate that GADSO is able to produce highly conformal dose distributions using 20–30 deliverable segments per treatment within a clinically acceptable computation time.
Static and dynamic polarizabilities of Na-like ions

We have calculated static and frequency-dependent polarizabilities for the ground states of neutral Na and four sodium-like ions Mg+, Al2+, Si3+ and P4+. The polarizability is expressed in terms of the second-order energy correction, when the electric field is treated as a perturbation. The zero- and first-order wavefunctions are expressed as configuration interaction expansions. The radial parts of the one-electron functions are optimized, some on the ground or first excited state energies, others on the second-order energy correction (i.e. the polarizability). The wavefunctions can also be used as target state functions in electron–atom and electron–ion scattering.
High frequency integrated feed for front end circuitry and antenna arrays

Low‐cost printed circuit board waveguide (PCBWG) technology is employed to develop new waveguide‐fed microstrip antenna arrays with low profile and light weight while maintaining high efficiency and gain at 12.5 GHz. The proposed corporate feed network has two parts: on the antenna layer, microstrip lines are used to form a 2 × 4 sequentially rotated sub‐array of circularly polarized microstrip patches and on the feed layer PCB‐WG is utilized to combine any number of these sub‐arrays to form a larger array. Because PCB‐WGs transmit the power over a large portion of the feed network, losses are substantially reduced and spurious radiations from feed circuit are eliminated. Several microstrip arrays with PCBWG feed were designed and fabricated using standard PCB process. Comparing the results with those of a hybrid array with conventional waveguide feed shows that there is only a negligible degradation in gain and efficiency when bulky and expensive aluminum waveguides are replaced by PCB‐WGs. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.
Warm Dark Matter from keVins

We propose a simple model for Warm Dark Matter (WDM) in which two fermions are added to the Standard Model: (quasi-) stable ``keVins'' (keV inert fermions) which account for WDM and their unstable brothers, the ``GeVins'' (GeV inert fermions), both of which carry zero electric charge and zero lepton number, and are (approximately) ``inert'', in the sense that their only interactions are via suppressed couplings to the Z. We consider scenarios in which stable keVins are thermally produced and their abundance is subsequently diluted by entropy production from the decays of the heavier unstable GeVins. This mechanism could be implemented in a wide variety of models, including E6 inspired supersymmetric models or models involving sterile neutrinos.
Intensity-modulated radiotherapy optimization with gEUD-guided dose–volume objectives

Currently, most intensity-modulated radiation therapy systems use dose–volume (DV)-based objectives. Although acceptable plans can be generated using these objectives, much trial and error is necessary to plan complex cases with many structures because numerous parameters need to be adjusted. An objective function that makes use of a generalized equivalent uniform dose (gEUD) was developed recently that has the advantage of involving simple formulae and fewer parameters. In addition, not only does the gEUD-based optimization provide the same coverage of the target, it provides significantly better protection of critical structures. However, gEUD-based optimization may not be superior once dose distributions and dose–volume histograms (DVHs) are used to evaluate the plan. Moreover, it is difficult to fine-tune the DVH with gEUD-based optimization. In this paper, we propose a method for combining the gEUD-based and DV-based optimization approaches to overcome these limitations. In this method, the gEUD optimization is performed initially to search for a solution that meets or exceeds most of the treatment objectives. Depending on the requirements, DV-based optimization with a gradient technique is then used to fine-tune the DVHs. The DV constraints are specified according to the gEUD plan, and the initial intensities are obtained from the gEUD plan as well. We demonstrated this technique in two clinical cases: a prostate cancer and a head and neck cancer case. Compared with the DV-optimized plan, the gEUD plan provided better protection of critical structures and the target coverage was similar. However, homogeneities were slightly poorer. The gEUD plan was then fine-tuned with DV constraints, and the resulting plan was superior to the other plans in terms of the dose distributions. The planning time was significantly reduced as well. This technique is an effective means of optimizing individualized treatment plans.
Real-time implementation of a novel hybrid fuzzy sliding mode control of a BLDC motor

This paper presents a novel hybrid control of a BLDC motor using a mixed sliding mode and fuzzy logic controller. The objective is to build a fast and robust controller which overcome classical controllers’ inconveniences and exploit the fast response of brushless dc motors characterized by an intense torque and fast response time. First the paper study pros and cons of both sliding mode and fuzzy logic controllers. Then the novel controller and its stability demonstration are presented. Finally the proposed controller method is used for the speed control of a BLDC motor 3KW. The obtained results are compared with those of a fuzzy logic and a conventional sliding mode controller. It allows to show performance of the proposed controller in terms of speed response and reaction against disturbances, which is improved more than 5 times without losing stability or altering tracking accuracy
Newtonian hydrodynamics with general relativistic pressure

We present the general relativistic pressure correction terms in Newtonian hydrodynamic equations to the nonlinear order: these are equations (1.1)–(1.3). The derivation is made in the zero-shear gauge based on the fully nonlinear formulation of cosmological perturbation in Einstein's gravity. The correction terms differ from many of the previously suggested forms in the literature based on hand-waving manners. We confirm our results by comparing with (i) the nonlinear perturbation theory, (ii) the first order post-Newtonian approximation, and (iii) the special relativistic limit, and by checking (iv) the consistency with full Einstein's equation.
Destruction of magnetic surfaces by magnetic field irregularities: Part II

The present work is a continuation of the paper by Rosenbluth et al. (Nucl. Fusion 6 (1966) 297) and concerns the investigation of problems associated with the condition for the existence of magnetic surfaces in closed systems of the stellarator type. The unperturbed geometry of the magnetic field is produced by a straight helical field. Exact equations for the motion of the magnetic field lines are put into Hamiltonian form and action-phase variables are introduced. The authors study the effect on magnetic field geometry of a perturbation that is periodic with respect to the co-ordinate along the toroidal axis. It is shown that, if the perturbation is greater than some critical value, the motion of those field lines that are at a sufficient distance from the toroidal axis is similar to Brownian motion and leads to the destruction of the magnetic surfaces. The authors derive the explicit form of the condition forstochastic instability of the magnetic field lines and estimate the coefficient of field line diffusion from the volume. With the above method it is possible to consider the most important form of perturbation in stellarator systems, occurring when the cylindrical, helical field is bent into a torus. Irrespective of the magnitude of the correction for the toroidality of the geometry, destruction of the magnetic surfaces occurs near the separatrix of the unperturbed magnetic field, and this effectively reduces the region bounded by the separatrix of the perturbed field. When the toroidal perturbations are small, the destruction is of a stochastic nature. It follows from the estimate made of the region where destruction takes place that the maximum shear permissible in toroidal systems is substantially limited. In conclusion, the authors present computer calculation results illustrating the stochastic nature of the destruction of the magnetic surfaces.
A new equivalent circuit for inverters and its application for the determination of coupling matrix elements of narrow RF bandpass filters

A new equivalent circuit for inverters is presented. Using this circuit, expression for the elements of the coupling matrix of narrow RF band pass filters is derived. The derivation is based on frequency independent coupling assumed in the synthesis of narrow RF band pass filters. Our expression is different from an earlier expression obtained using lumped circuit representations of different types of coupling and their analysis. It is shown that the earlier expression can be derived from our analysis if the coupling is assumed frequency‐variant. Unlike earlier work, our derivation shows how the sign of the coupling coefficient can be obtained. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.
Electron capture and excitation in slow H+ + He*(n = 3) collisions

The electron-capture and excitation processes in slow collisions of protons with He*(1s3l) are studied using the close-coupling method within the semiclassical approximation. The Stark splitting of electron-capture states on H is explicitly taken into account and the coupling-matrix elements between these states and the initial angular-momentum states on He are calculated analytically. The cross sections for excitation (de-excitation) and single-electron capture to specific spherical hydrogen states have been calculated in the relative velocity range 2×106-1.3×108 cm s-1. The cross section values for both types of processes in the considered velocity range are found to be large (10-14-10-13 cm2) due to the large values of electron-exchange couplings at large internuclear distances. The excitation (de-excitation) processes are controlled by two-step exchange (capture and re-capture) transitions rather than by direct coupling among the states centred on He.
Nonlinear power spectrum from resummed perturbation theory: a leap beyond the BAO scale

A new computational scheme for the nonlinear cosmological matter power spectrum (PS) is presented. Our method is based on evolution equations in time, which can be cast in a form extremely convenient for fast numerical evaluations. A nonlinear PS is obtained in a time comparable to that needed for a simple 1-loop computation, and the numerical implementation is very simple. Our results agree with N-body simulations at the percent level in the BAO range of scales, and at the few-percent level up to k ≃ 1 h/Mpc at z≳0.5, thereby opening the possibility of applying this tool to scales interesting for weak lensing. We clarify the approximations inherent to this approach as well as its relations to previous ones, such as the Time Renormalization Group, and the multi-point propagator expansion. We discuss possible lines of improvements of the method and its intrinsic limitations by multi streaming at small scales and low redshifts.
Fitting interatomic potentials using molecular dynamics simulations and inter-generation projection genetic algorithm

In this paper we propose a new algorithm to fit interatomic potentials. In the new algorithm, molecular dynamics simulations are applied to calculate the material properties which are used to match the experimental data during the fitting procedure. This includes the effect of atom relaxations in fitting calculations. An inter-generation projection genetic algorithm is used to optimize the fitting parameters until the error between the calculated and experimental material properties is within tolerance. This leads to a global optimal solution. The new algorithm significantly improves the accuracy and transferability of the fitted potential. It has been demonstrated by a numerical example of fitting potential of nickel.
The structure and tribological properties of gradient layers prepared by plasma-based ion implantation on 2024 Al alloy

Using plasma-based ion implantation, two types of gradient layers have been prepared on 2024 Al alloy. One is prepared by N-implantation then C-deposition, the other adds an interlayer composed of a Ti layer and a Ti–N layer between N-implantation and C-deposition. C-deposition is carried out at various implanting voltages or C2H2/H2 ratios. The composition depth profiles of these layers were characterized by x-ray photoelectron spectroscopy. The structure, morphologies and microstructure of the C layers were studied using Raman spectroscopy, atomic force microscope and transmission electron microscope, respectively. The surface hardness was measured with a Knoop tester and a mechanical property microprobe. The dry ball-on-disc wear tests were performed in ambient air. The gradient layer without interlayer is composed of an N-implanted layer rich in AlN and a diamond-like carbon (DLC) layer (film), and the two layers are connected with a C–Al transition layer containing Al4C3. The Ti layer rich in α -Ti and the N-implanted layer are connected by a Ti–Al transition layer containing TiAl3, while the Ti–N layer rich in TiN and the DLC film are connected by a C–Ti transition layer containing TiC, TiCN, etc. Thus, the gradient layer with interlayers has optimized the gradient structure. DLC films are compact and amorphous, contain high sp3/sp2 ratios and depend on the implanting voltage and the C2H2/H2 ratio. Similarly, these gradient layers exhibit significant improvement in morphologies, surface hardness and tribological properties; the interlayer, the implanting voltage and the C2H2/H2 ratio all have prominent effects on these properties.
Pulse Sequence Analysis - a diagnostic tool based on the physics behind partial discharges

The analysis of partial discharge signals is a well-known tool to monitor the degradation of electric equipment. In contrast to the common practice of the analysis of data sets (phase angles of occurrence and discharge magnitudes) accumulated during a predefined time interval, the Pulse Sequence Analysis (PSA) is based on the evaluation of data sets in which also the individual sequence or partial discharge events are registered. The classical analyses are mainly based on the frequency distributions of the pulse heights of discharge events and the phase angles of the applied voltage at which they occur. Detailed analyses of partial discharge sequences reveal that - if liquid or solid dielectrics are involved - the phase angle of the externally applied voltage is not a meaningful parameter in the partial discharge process. The ignition of the partial discharge is determined by the local electric field at the defect site and not by the absolute value or the phase angle of the externally applied voltage. Experiments with different model defects as well as measurements of commercial apparatuses show that there are characteristic sequences of partial discharge events. In many cases a systematic shift of the phase angles of occurrence occurs, which produces an apparently `statistic scatter' of the phase angles unless the correlation between consecutive discharges is taken into account. Sequence correlated parameters such as the voltage differences of the applied voltage or time differences between consecutive discharges are far more decisive parameters in the process. By means of the pulse sequence analysis, local defects can be characterized more precisely and single and multiple discharge sites can be clearly distinguished. A physically based model to describe discharge phenomena will be discussed and experimental results will be compared with results of numerical simulations of partial discharge processes.
Numerical simulation of microfluidic injection processes in crossing microchannels

The design and operation control of microfluidic devices have drawn a great deal of attention over the last decade due to the emerging lab-on-a-chip applications. Cross-shaped microchannels connecting liquid reservoirs are typical configurations of the microfluidic chips. Normally the microchannels have a large length-to-width aspect ratio (typically 1500:1), therefore, the transport phenomena in these microchannels are essentially multiscale and multidimensional problems. There are no analytical solutions existing for such kind of problems and it has been found that effectively and efficiently simulating the transport phenomena in such microchannels is very difficult. A numerical model developed here uses the designed boundaries to truncate the physical domain to a small computation domain in order to concentrate computing power in the areas exhibiting multidimensional phenomena (such as intersections) and apply analytical functions in the areas of one-dimensionality (such as fully developed flow region). This model is employed to simulate the flow and mass transport processes in a planar glass chip with a cross-shaped microchannel, and the model predictions are compared to the experimental results. Agreement between the model predictions and experimental results verified that this newly developed model is capable of accurately and efficiently simulating the transport phenomena in microfluidic devices.
An Efficient Approach to Detecting Missing Tags in RFID Data Stream

RFID technology is a Radio frequency identification system that provides a reader reading the data item from its tag. Nowadays, RFID system has rapidly become more common in our life because of its autonomous advantages compared to the traditional barcode. It can detect hundreds of tagged items automatically at a time. However, in RFID, missing tag detection can occur due to signal collisions and interferences. It will cause the system to report incorrect tag’s count due to an incorrect number of tags being detected. The consequences of this problem can be enormous to business, as it will cause incorrect business decisions to be made. Thus, a Missing Tag Detection Algorithm (MTDA) is proposed to solve the missing tag detection problem. There are many other existing approaches has been proposed including Window Sub-range Transition Detection (WSTD), Efficient Missing-Tag Detection Protocol (EMD) and Multi-hashing based Missing Tag Identification (MMTI) protocol. The result from experiments shows that our proposed approach performs better than the other in terms of execution time and reliability.
Characterization and suppression of edge and aliasing artefacts in iterative x-ray CT reconstruction

For the purpose of obtaining x-ray tomographic images, statistical reconstruction (SR) provides a general framework with possible advantages over analytical algorithms such as filtered backprojection (FBP) in terms of flexibility, resolution, contrast and image noise. However, SR images may be seriously affected by some artefacts that are not present in FBP images. These artefacts appear as aliasing patterns and as severe overshoots in the areas of sharp intensity transitions (‘edge artefacts’). We characterize this inherent property of iterative reconstructions and hypothesize how discretization errors during reconstruction contribute to the formation of the artefacts. An adequate solution to the problem is to perform the reconstructions on an image grid that is finer than that typically employed for FBP reconstruction, followed by a downsampling of the resulting image to a granularity normally used for display. Furthermore, it is shown that such a procedure is much more effective than post-filtering of the reconstructions. Resulting SR images have superior noise–resolution trade-off compared to FBP, which may facilitate dose reduction during CT examinations.
Experimental assessment of the current-limiting mechanisms in BSCCO/Ag high-temperature superconducting tapes

The current - voltage characteristics and the magnetic field dependence of the critical current of a range of mono-core BSCCO 2223 tapes are presented, illustrating the complementary use of transport and magnetization experiments in determining and analysing the current-limiting dissipation processes in these HTS conductors. Below a magnetic cross-over field the samples resemble a Josephson-linked current network, with the dominant dissipation at the weakest grain boundaries. In this regime, increasing field leads to a gradual fragmentation of the network. The network homogeneity and connectivity can be inferred from screening current length-scale measurements and comparison of transport and magnetization measurements. Above the cross-over field , flux motion within the surviving strongly linked backbone dominates the dissipation. The details of the dependences of the critical current and flux creep rate on magnetic field can be used to examine the intragranular pinning potential in the tapes. We show that, despite the wide range of transport critical-current values of the samples examined, the intragranular pinning proves to be remarkably sample independent. We conclude that while at low fields may be increased by improved processing that yields better intergrain connectivity, the high-field can be enhanced only by strengthening the pinning within the BSCCO 2223 crystallites themselves.