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- 2018
- Plastic rod scintillator
- Radiation interaction position
- Artificial Neural Network
- Position sensitive detector
- Optoelectronic Information Science and Engineering
- University of Qom
- Shahrood University of Technology
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Analytic and simulative comparison of turbulent FSO system with different modulation techniques
摘要： In this paper, we characterize the performance of Intensity Modulation/Direct Detection (IM/DD) and coherent detection modulation techniques in free-space optical (FSO) communication system in terms of bit error rate (BER). The system of interest includes M-ary Pulse Position Modulation (M-PPM) in correspondence to IM/DD and M-ary Phase Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) with respect to coherent detection. The system is subjected to weak turbulence regime of log-normal channel with scintillation index less than 0.75. Coherent techniques involve the amount of signal pulses transmitted in a particular time as the major component of their generation, except IM/DD which is a result of photon intensity, i.e. the number of photons forming a pulse. It is worth mentioning that in previous studies, the performance of IM/DD techniques had been evaluated in terms of photon-count fluctuation statistics and thus the impact of fading strength of channel on signal intensity was not discussed anywhere. In this work, an objective equivalence has been achieved between these two kinds of detection by deriving the BER expression of M-PPM in terms of probability density function of signal intensity, while considering fading strength, scintillation index, thermal noise and outage probability as system parameters for numerical analysis.
关键词： M-ary Pulse Position Modulation (MPPM),M-ary Phase Shift Keying (MPSK),M-ary Quadrature Amplitude Modulation (M-QAM),Intensity Modulation/Direct Detection (IM/DD),Scintillation index,Coherent detection
更新于2025-09-19 17:15:36
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Indoor Scene and Position Recognition Based on Visual Landmarks Obtained from Visual Saliency without Human Effect
摘要： Numerous autonomous robots are used not only for factory automation as labor saving devices, but also for interaction and communication with humans in our daily life. Although superior compatibility for semantic recognition of generic objects provides wide applications in a practical use, it is still a challenging task to create an extraction method that includes robustness and stability against environmental changes. This paper proposes a novel method of scene and position recognition based on visual landmarks (VLs) used for an autonomous mobile robot in an environment living with humans. The proposed method provides a mask image of human regions using histograms of oriented gradients (HOG). The VL features are described with accelerated KAZE (AKAZE) after extracting conspicuous regions obtained using saliency maps (SMs). The experimentally obtained results using leave-one-out cross validation (LOOCV) revealed that recognition accuracy of high-saliency feature points was higher than that of low-saliency feature points. We created our original benchmark datasets using a mobile robot. The recognition accuracy evaluated using LOOCV reveals 49.9% for our method, which is 3.2 percentage points higher than the accuracy of the comparison method without HOG detectors. The analysis of false recognition using a confusion matrix examines false recognition occurring in neighboring zones. This trend is reduced according to zone separations.
关键词： visual landmark,machine learning,saliency maps,semantic position recognition,histograms of oriented gradients
更新于2025-09-19 17:15:36
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Quantitative evaluation of sulfation position prevalence in chondroitin sulphate by Raman spectroscopy
摘要： Chondroitin sulphate (CS) as a major component of the extracellular matrix of numerous connective tissues is responsible for biomechanical properties such as resistance and elasticity. It occurs in different isomeric forms with different sites and degrees of sulfation. The characterization of crude CS and quantitative isomeric identification by high‐performance liquid chromatography (HPLC) requires specific enzymes, expensive reagents, and a complicated analytical process. Poor reproducibility and imprecise quantification were found with other methodologies. Raman spectroscopy allows rapid and reproducible identification of CS isomers offering specificity and avoids the need for sample pretreatment or external markers. In the present work, a quantitative identification of major contribution of isomeric chondroitin 4 and 6‐sulphate in crude CS by Raman spectroscopy has been performed. Two quantitative indices have been proposed based on areas of specific bands of interest related to main skeletal modes, an aromatic ring with axial orientation in the case of the major contribution of 4‐sulphate and C‐O‐(S) vibration, which is heavily detected in the case of the major contribution of 6‐sulphate. Both mammalian and fish sources of CS were used to validate the ability of mentioned indices to discriminate between prevalence of 4‐sulphate, 6‐sulphate, or none of them. Correspondence of given results with HPLC was demonstrated.
关键词： quantitative indices,sulfation position,Raman spectroscopy,chondroitin sulphate
更新于2025-09-19 17:15:36
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A new approach to the schrodinger equation with position-dependent mass and its implications in quantum dots and semiconductors
摘要： In this study, we introduce a new approach to construct the Schr?dinger equation with position-dependent mass characterized by an emerging particle’s effective mass, in perfect analogy with the problems involving a position-dependent mass particle in semiconductor heterostructures. We have discussed several of its properties and some of its implications in quantum dots and semiconductors. It was observed that the PDM approach affects only semiconductors with large interatomic scaling such as non-crystalline semiconductors and its effect on conventional semiconductors is insignificant.
关键词： spatial transformation,quantum dots,Position-dependent mass,interatomic scaling
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Investigation on Temperature Coefficients of Crystalline Silicon Solar Modules before and after Potential-induced Degradation
摘要： The influences of the intermediate band (IB) filling, the absorption coefficient constants, and the IB position on the efficiency of a quantum dot intermediate band solar cell (QD-IBSC) are investigated considering the spatial variation of subbandgap generation rates. A new definition of optimal intermediate band filling is proposed. A mathematical model is developed to optimize the intermediate band solar cell (IBSC) structure under idealized conditions, which calculates the optimal ratio of the subbandgap absorption coefficient constants and the optimal position of IB.
关键词： optimal filling,conversion efficiency,Intermediate band solar cell (IBSC),IB position,absorption coefficients
更新于2025-09-19 17:13:59
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Quantum diffraction of position-momentum entangled photons from a sharp edge
摘要： In this paper, an experiment of quantum diffraction of position-momentum entangled photons from a straight sharp edge is presented. Path of a single photon of an entangled pair is partially blocked by a sharp edge whereas the other photon is detected at a stationary location without revealing the which-path information of the other photon. Quantum diffraction pattern of the sharp edge is revealed only in the correlated conditional detection of spatially separated photons and no diffraction pattern is formed in local detections of individual photons. Theoretical analysis of the quantum diffraction of position-momentum entangled photons from a sharp edge is also presented in this paper. Experimental measurements of the quantum diffraction pattern are compared with theoretically calculated quantum diffraction pattern of position-momentum entangled photons.
关键词： Photon entanglement,Quantum interference,Quantum diffraction,Position-momentum entanglement
更新于2025-09-19 17:13:59
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[IEEE 2018 IEEE International Conference on Information and Automation (ICIA) - Wuyishan, China (2018.8.11-2018.8.13)] 2018 IEEE International Conference on Information and Automation (ICIA) - The Influence of Cambered Optical Fairing on the Light Beam of Underwater Laser Fuze <sup>*</sup>
摘要： Position and orientation of indoor mobile robots must be obtained real timely during operation in structured industrial environment, so as to ensure the security and efficiency of cargo transportation and assembly precision. But for such a large-scale space, only 2-D coordinates and heading angle of the mobile robot can be measured with a relatively low precision in current major methods. This paper presents a novel method for 3-D position and orientation measurement of indoor mobile robot. In this method, a rotary-laser transmitter is utilized, which is mounted on the indoor mobile robot measuring the scanning angles relative to photoelectric artificial landmarks and obtaining its own 3-D space location information. The landmarks whose coordinates in navigation frame should be precalibrated are distributed at the most appropriate positions of the structured industrial environment. On the basis of that, an algorithm of multiangle intersection was established and in-depth discussed to solve transmitter’s spatial position and orientation. Experimental results show that, in an 8 m × 6 m × 2.5 m working volume, transmitter’s position, and orientation measurement accuracy of proposed method were higher than 3.8 mm and 0.104°, respectively. It demonstrates that the proposed method is reliable and flexible for indoor mobile robot navigation tasks and the measurement accuracy can be further improved by increasing layout density of landmarks.
关键词： measurement,orientation,position,navigation,large-scale space,3-D
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - A Novel Approach to Amine-Thiol Molecular Precursors for Fabrication of High Efficiency Thin Film CISSe/CIGSSe Devices
摘要： 3-D coordinate transformation, which is based on aligning two sets of common reference points, is frequently applied in large-scale combined measurement to unify coordinate frames and tie individual measurement systems together. However, it introduces uncertainty into the ?nal measurement results. This uncertainty must be quanti?ed to make the results complete. This paper presents a novel approach to the uncertainty analysis of 3-D coordinate transformation based on the weighted total least squares adjustment. This approach takes full account of the uncertainty characteristics of measuring instruments and is simple in calculation. In this approach, the transformation uncertainty of a point in a world frame is analyzed carefully. The simulations show that the transformation uncertainty has a distribution of concentric ellipsoids and is affected by the measurement uncertainties and layout of common points. Besides, strategies for minimizing transformation uncertainty are recommended. The experimental results from a laser tracker prove that this proposed approach is valid under normal instrument operating conditions and that these strategies are feasible and ef?cient.
关键词： Coordinate transformation,error analysis,uncertainty,large-scale metrology,position measurement,sensor fusion
更新于2025-09-19 17:13:59
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[IEEE 2019 5th International Conference on Advances in Electrical Engineering (ICAEE) - Dhaka, Bangladesh (2019.9.26-2019.9.28)] 2019 5th International Conference on Advances in Electrical Engineering (ICAEE) - Structural properties of bi-layer Molybdenum Thin-film deposited by RF magnetron sputtering for CZTS solar cells
摘要： This paper presents a novel method for tracking the position of a medical instrument’s tip. The system is based on phase locking a high frequency signal transmitted from the medical instrument’s tip to a reference signal. Displacement measurement is established having the loop open, in order to get a low frequency voltage representing the medical instrument’s movement; therefore, positioning is established by means of conventional measuring techniques. The voltage-controlled oscillator stage of the phase-locked loop (PLL), combined to an appropriate antenna, comprises the associated transmitter located inside the medical instrument tip. All the other low frequency PLL components, low noise amplifier and mixer, are located outside the human body, forming the receiver part of the system. The operating details of the proposed system were coded in Verilog-AMS. Simulation results indicate robust medical instrument tracking in 1-D. Experimental evaluation of the proposed position tracking system is also presented. The experiments described in this paper are based on a transmitter moving opposite a stationary receiver performing either constant velocity or uniformly accelerated movement, and also together with two stationary receivers performing constant velocity movement again. This latter setup is implemented in order to demonstrate the prototype’s accuracy for planar (2-D) motion measurements. Error analysis and time-domain analysis are presented for system performance characterization. Furthermore, preliminary experimental assessment using a saline solution container to more closely approximate the human body as a radio frequency wave transmission medium has proved the system’s capability of operating underneath the skin.
关键词： radio frequency (RF),Displacement measurement,position tracking,medical instrument,phase shift
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Spectral Engineering of Photonic Filters Based on Mode Splitting in Self-Coupled Silicon Nanowire Waveguides
摘要： Recently, position-patch-based face hallucination methods have received much attention, and obtained promising progresses due to their effectiveness and ef?ciency. A locality-constrained double low-rank representation (LCDLRR) method is proposed for effective face hallucination in this paper. LCDLRR attempts to directly use the image-matrix based regression model to compute the representation coef?cients to maintain the essential structural information. On the other hand, LCDLRR imposes a low-rank constraint on the representation coef?cients to adaptively select the training samples that belong to the same subspace as the inputs. Moreover, a locality constraint is also enforced to preserve the locality and the sparsity simultaneously. Compared with previous methods, our proposed LCDLRR considers locality manifold structure, cluster constraints, and structure error simultaneously. Extensive experimental results on standard face hallucination databases indicate that our proposed method outperforms some state-of-the-art algorithms in terms of both visual quantity and objective metrics.
关键词： low-rank representation,position-patch,Face hallucination,nuclear norm
更新于2025-09-19 17:13:59