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- 2019
- Distributed optical fiber sensing
- Optical frequency domain reflection
- Polynomial regression algorithm
- Nonlinear tuning compensation
- Optoelectronic Information Science and Engineering
- Hebei University of Technology
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Machine Learning Identification of the Sensing Descriptors Relevant in Molecular Interactions with Metal Nanoparticle-Decorated Nanotube Field-Effect Transistors
摘要： Carbon nanotube-based field-effect transistors (NTFETs) are ideal sensor devices as they provide rich information regarding carbon nanotube interactions with target analytes and have potential for miniaturization in diverse applications in medical, safety, environmental, and energy sectors. Herein, we investigate chemical detection with cross-sensitive NTFETs sensor arrays comprised of metal nanoparticle-decorated single-walled carbon nanotubes (SWCNTs). By combining analysis of NTFET device characteristics with supervised machine learning algorithms, we have successfully discriminated among five selected purine compounds – adenine, guanine, xanthine, uric acid, and caffeine. Interactions of purine compounds with metal nanoparticle-decorated SWCNTs were corroborated by density functional theory (DFT) calculations. Furthermore, by testing a variety of prepared, as well as commercial solutions with and without caffeine, our approach accurately discerns the presence of caffeine in 95% of the samples with 48 features using a linear discriminant analysis (LDA) and in 93.4% of the samples with only 11 features when using a support vector machine (SVM) analysis. We also performed recursive feature elimination and identified three NTFET parameters – transconductance, threshold voltage, and minimum conductance – as the most crucial features to analyte prediction accuracy.
关键词： support vector machine,linear discriminant analysis,sensor arrays,graphene,carbon nanotubes
更新于2025-09-23 15:19:57
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Detection of the focal spot motion relative to the collimator axis of a linear accelerator under gantry rotation
摘要： The potential for delivering high precision radiotherapy using linear accelerators (linacs) has been improved with the development of digital x-ray electronic portal imaging devices (EPID) for acquiring kilovoltage (kV) cone-beam CT and megavoltage (MV) images for patient positioning. EPIDs have also opened the possibilities of developing novel quality assurance and insight into radiotherapy equipment performance. The aim of this work was to measure the offset of the focal spot position (FSP) of a linac under gantry rotation relative to the collimator axis using an EPID. The focal spot was assumed to be a point source of MV x-ray generation. A special phantom was designed for attachment to the gantry head and supporting two tungsten-carbide ball-bearings at two different distances from the focal spot. The methodology was demonstrated on a series of images acquired of the phantom on three Elekta linacs in clinical use with 6 MV flattening-filter-free (FFF) beams. The gantry and collimator were rotated 360° in steps of 30°. For each position an image of the phantom was acquired using the EPID. Each series consisted of 169 EPID images. The images were analysed using in-house developed software. Analyses of the EPID images acquired with 6 MV FFF beams showed that the focal spot motion amplitudes relative to the collimator axis during gantry rotation in the longitudinal and lateral directions were less than 0.10 mm and 0.50 mm, respectively, for an optimized 6 MV FFF FSP calibrated linac.
关键词： MV radiation,focal spot,ball-bearing,EPID,collimator,linear accelerator
更新于2025-09-23 15:19:57
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Eigenwaves in Sommerfeld–Goubau Line: Spectrum
摘要： The problem on normal waves in an inhomogeneous metal-dielectric waveguide structure is reduced to a boundary value problem for the longitudinal components of the electromagnetic field in Sobolev spaces. Nonhomogeneous filling and entering of spectral parameter in transmission conditions leads to necessity of special definition of solution of the problem. We formulate the definition of solution using variational relation. The variational problem is reduced to the study of an operator function. We investigate properties of the operators of the operator function needed for the analysis of its spectral properties. We prove theorem of discrete spectrum and theorem of localization of eigenvalues of the operator-function on complex plane.
关键词： operator-function,inhomogeneous waveguide,Maxwell’s equations,non-linear eigenvalue problem,spectrum,Non-polarized azimuthal-symmetric electromagnetic waves
更新于2025-09-19 17:15:36
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Preparation, Structural, Spectroscopic, Thermal, Linear and Nonlinear Optical Characteristics of Semi-Organic Material: Samarium Chloride-Thiourea-L-Tartaric acid
摘要： Samarium chloride-thiourea-l-tartaric acid (SCTuT): a semi-organic material was prepared in the form of a single crystal with an orthorhombic crystal structure and a space group Pnma. The crystallinity and purity of the single crystals were tested by powder X-ray diffraction. The scanning electron microscopy (SEM) analysis shows the rod-like microstructure. Energy dispersive X-ray analysis has confirmed the elemental composition. Fourier transform infrared and Raman spectroscopy analysis established the mode of coordination and functional groups. The thermal effects such as dehydration, melting and decomposition, etc. were observed by the thermogravimetric and differential thermoanalytical (TGA/DTA) analysis. Linear and non-linear characteristics of the compound were studied in detail. The optical band transitions due to C=O and C=S chromophores remain active in grown crystals and thus are recorded in the UV-Vis optical spectrum. The crystals possess finite values of non-linear absorption, non-linear refraction and third order nonlinearity as confirmed by Z-scan experiments.
关键词： Spectroscopic Analysis,Semi-organic Material,Non-Linear Optical Properties
更新于2025-09-19 17:15:36
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[IEEE 2018 International conference on Computing, Electronic and Electrical Engineering (ICE Cube) - Quetta, Pakistan (2018.11.12-2018.11.13)] 2018 International Conference on Computing, Electronic and Electrical Engineering (ICE Cube) - Design and Simulation of Molten Salt Based Solar Thermal Power Plant using LFR Technology in Pakistan
摘要： Pakistan being an underdeveloped country is facing several problems. One of the most important problems of the country has been Energy crises. Pakistan has very rich resources of renewable energy which are yet to be utilized. Among these renewable energy resources, energy from sun is one of the most abundant one. Concentrated Solar power CSP is considered to be the best technology to generate electricity for solar energy. Design of a CSP plant with a capacity of 100 MW using Linear Fresnel Reflectors and integrated with thermal energy storage of six hour is proposed in this paper. A location near Nawabshah receiving direct normal irradiance (DNI) of 1955 KWh/m2/year is selected on the basis of CSP plant requirements. System advisor model (SAM) selected for carrying out the simulation of the proposed plant for one year. Heat transfer fluid is molten salt known as Hitec solar Salt instead of using synthetic oil. From simulation results it was found that the plant can generate 220,734,832 kWh (220.735 GWh) of electricity annually. The capacity factor and gross to net conversion were found to be 25.2% and 90% respectively. These results obtained are encouraging and justify that a plant based on the proposed model is thermodynamically feasible in Pakistani environment.
关键词： Solar Energy,Concentrated Solar Thermal Power,Renewable Energy,Electricity,System Advisor Model,Pakistan,Linear Fresnel Reflector
更新于2025-09-19 17:15:36
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An Easily Fabricated Linear Piezoelectric Actuator Using Sandwich Longitudinal Vibrators With Four Driving Feet
摘要： A piezoelectric actuator using three sandwich longitudinal vibrators is proposed and tested. The two horizontal vibrators are parallel to each other and orthogonal to the vertical vibrator. The ends of the two horizontal vibrators serve as the four driving feet. The actuator has a simple fabricating process, which will shorten the period of fabrication. Two modes of the actuator are used to get the elliptical trajectories on the driving feet. The frequencies of the two modes are tuned to be about 21.60 kHz with modal analysis by the finite element method (FEM). The operating principle is also examined with transient analysis by FEM. A prototype is fabricated and its vibration characteristics are verified by using a scanning laser Doppler vibrometer. The prototype shows the best mechanical performance with the optimum working frequency and phase difference of 18.50 kHz and 60°, respectively. The typical output of the prototype is a no-load speed of 439.41 mm/s, a maximum thrust of 40 N, and a maximum power of 5.01 W at the voltage of 200 VP?P. The mechanical characteristics of the prototype show that the exciting voltages can be used for the speed control due to the approximately linear relationship between them.
关键词： resonant state,vibration test.,Linear piezoelectric actuator,sandwich longitudinal vibrators
更新于2025-09-19 17:15:36
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Nonlinear Performance of Few-Mode Fiber Links with Intermediate Coupling
摘要： This paper reviews and extends the study of nonlinear performance of few-mode fiber links operating in all different linear coupling regimes for different mode delay maps. Nonlinear performance was estimated using the four-wave-mixing theory and the split-step Fourier method including semi-analytical solutions for linear mode coupling of arbitrary strength. The optimum link configurations minimizing the nonlinear penalty at practical levels of training sequence length are presented, including: the required coupling strength to give nonlinear distortion below that of the single-mode propagation without mode coupling, and the impact of mode delay maps. Finally, different approximate solution methods of the multimode nonlinear Schr?dinger equation are compared, highlighting the accuracy of a stochastic solution method including distributed linear mode coupling.
关键词： Mode-division multiplexing,few-mode fiber,linear mode coupling,fiber nonlinearity
更新于2025-09-19 17:15:36
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[IEEE 2018 26th Telecommunications Forum (TELFOR) - Belgrade, Serbia (2018.11.20-2018.11.21)] 2018 26th Telecommunications Forum (TELFOR) - Assessment of Linear Sampling Method and Factorization Method for Through the Wall Imaging
摘要： In this study, we considered a through wall imaging scenario with microwaves. The scattered field is calculated via Method of Moment and background is estimated by mean electrical properties of the wall. In order to reconstruct targets in investigated domain, two qualitative imaging methods, namely linear sampling method and factorization method are applied. These methods are applied and compared with respect to various criteria such as selection of regularization parameters, selection operating frequency, thickness of the wall and conductivity of the wall.
关键词： Factorization method,Linear sampling method,Through the wall imaging
更新于2025-09-19 17:15:36
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Association of 1-hexanol in mixtures with n-hexane: Dielectric, near-infrared and DFT studies
摘要： Association of 1-hexanol in n-hexane has been studied by measurements of nonlinear dielectric effect (NDE) and near-infrared (NIR) spectroscopy. Besides, the dipole moments of selected open and cyclic associates were determined by DFT (density functional theory) calculations. All measurements were performed in the whole range of mole fractions with a step of 0.1. From numerical fitting of the dielectric data we obtained populations of all species present in the mixture. Our results do not support common opinion about the exceptional role of cyclic tetramers. The most abundant cyclic species are trimers and population of the cyclic associates rapidly decreases with increasing size of associates. The variations in population of open associates are more complex and for mole fractions of 1-hexanol greater than 0.1 the relationships have a maximum, which shifts towards higher associates. In pure 1-hexanol this maximum is close to seven. From analysis of the dielectric data it results that at lower alcohol content dominate the cyclic species. When the concentration of 1-hexanol increases the equilibrium shifts towards formation of the linear associates. From NIR spectra we determined the overall population of the free OH in monomers and open associates. Next, these values were used for estimation of an average length of the open associates. It appears that an averaged size of the open associates determined from NIR spectra is higher than that from the dielectric data and these differences are more pronounced when the concentration of 1-hexanol increases. We discuss possible explanations of this observation. Assuming that the actual size of the open associates is between those obtained from both methods, one can estimate that the size of open associates is ranging from 3 to 15 in pure 1-hexanol. It seems that the higher associates are stabilized by interaction of the aliphatic chains.
关键词： NIR spectroscopy,1-hexanol,DFT,hydrogen bonding,associations,non-linear dielectric effect
更新于2025-09-19 17:15:36
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[ACM Press the 2018 International Conference - Prague, Czech Republic (2018.10.12-2018.10.14)] Proceedings of the 2018 International Conference on Sensors, Signal and Image Processing - SSIP 2018 - Constrained Attribute Selection for Stress Detection Based on Physiological Signals
摘要： We present a constrained attribute selection method that makes use of feature assessment based on the Fisher’s separation criterion followed by variety reduction post-processing. The post-processing incorporates task-specific constrain into the feature selection process, as this is expected to facilitate the subsequent data modeling and classification stages. Here we validate the proposed method in an experimental setup oriented towards acute stress detection based on physiological signals. The experimental results support that the proposed method brings advantage, when compared to three other cases: (i) the full set of features, (ii) a subset selected based on prior knowledge, (iii) and a subset selected based solely on Fisher’s separation criterion.
关键词： Fisher linear discriminant,Stress detection,Attribute selection,Electrocardiography (ECG),Galvanic skin response (GSR)
更新于2025-09-19 17:15:36