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- 实验方案
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Development of a sub-miniature gamma camera for multimodal imaging system
摘要： In the recent past, gamma-ray imaging detectors have achieved an intrinsic spatial resolution of less than 1 mm within a few centimeters of a useful field of view (UFOV). Unlike to conventional gamma cameras, which are large and heavy, the compact gamma-ray imaging detectors can improve the performances of the gamma cameras used in the various fields. In this study, we developed a sub-miniature gamma camera for a multimodal imaging system. The camera has a gamma-ray detector, miniature electronics modules, and a diverging hole collimator. The detector consisted of the sub-millimeter pixelated Ce:GAGG array and the silicon photomultiplier (SiPM) array module. We organized the miniature electronics modules according to the functions; an MPPC base board, analog signal processing board, integrated power supply board, and compact data acquisition (DAQ) base board. The diverging hole collimator widened an imaging area of the gamma camera from the UFOV of the detector. On the detector side, dimensions of each hole and septa were identical to the pixel and inter-pixel thickness of the reflector of scintillator array. For the intrinsic performance test, we acquired a flood map image of 729 (27 × 27) scintillator pixels, and the energy resolution was 18.9 % for an integrated energy histogram of 99mTc (140 keV). For the extrinsic performance test, we used the 57Co sheet source, and made a 99mTc line source using a capillary tube. The sources located at 10 cm apart from the collimator surface. The imaging area was three times wider than the UFOV of the detector. The system sensitivity was 19 CPM/μCi and the spatial resolution was 3.5 mm. The usability of the proposed gamma camera will not be confined to existing applications due to its compactness and novelty.
关键词： Sub-miniature gamma camera,Gamma camera performance evaluation,Front-end electronics,Multimodal imaging system,Diverging hole collimator
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Power & Energy Society General Meeting (PESGM) - Portland, OR, USA (2018.8.5-2018.8.10)] 2018 IEEE Power & Energy Society General Meeting (PESGM) - An advanced maximum power point capturing technique with supercapacitor for PV system
摘要： In this paper, the characteristic curves considering complete Current-Voltage (I-V) and Power-Voltage (P-V) relations for PV system are presented. Based on the I-V characteristic curve, a novel Maximum Power Point Capturing (MPPC) technique is proposed to overcome the steady-state oscillation and slow dynamic response problems existing in the conventional Maximum Power Point Tracking (MPPT) technique. In order to further mitigate the fluctuations for PV system, an appropriate supercapacitor (superC) is selected to be connected in parallel with the PV system. The simulation results demonstrate the designed MPPC-superC structure has a better performance than the conventional MPPT method and MPPC method in both steady-state and dynamic responses.
关键词： supercapacitor,MPPC,MPP,PV system
更新于2025-09-23 15:23:52
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An Efficient Technique using Modified p-q Theory for Controlling Power Flow in a Single-Stage Single-Phase Grid-Connected PV System
摘要： In this paper, an efficient power conditioning unit (PCU) is presented for a single-phase grid-connected photovoltaic system (GCPVS) incorporating both maximum power-point tracking (MPPT) and current control algorithms in a single-stage. Modified p-q theory is applied to derive the reference signal for a hysteresis band current (HBC) controller so that independently the active and reactive power sharing between the photovoltaic (PV) system and the grid can be controlled. Enhanced stability during the internal dynamics, caused by the variations in PV generation and load conditions, is the prime aspect of the controller. The performance of the proposed p-q theory correlated HBC controller is evaluated against tracking of maximum PV power and compensation of load reactive power under the changeable atmospheric and load conditions, and also compared with the widely used conventional proportional resonant (PR) controller to justify superiority. Simulation and experiment are carried-out under variable weather and different load conditions to validate acceptability of the proposed control scheme.
关键词： modified p-q theory,Single-stage,hysteresis band current (HBC) controller,grid-connected photovoltaic system (GCPVS),power flow controlling
更新于2025-09-23 15:23:52
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Blind Quality Index for Tone-Mapped Images Based on Luminance Partition
摘要： Tone-mapping operators (TMOs), which are designed to convert high dynamic range (HDR) images to standard low dynamic range (LDR) images for displaying on conventional devices, have gained extensive attention recently. The quality of tone-mapped images generated by different TMOs varies significantly, which depends upon the image contents and the parameter settings. A quality index that can accurately evaluate the performances of TMOs is thus highly needed. With this motivation, this paper presents a blind quality index based on luminance partition for tone-mapped images. It is based on the fact that the Human Visual System (HVS) has different sensitivities to image regions with different luminance levels. Specifically, two adaptive thresholds are first employed to segment an image into the dark, bright and normal areas. Then, we calculate the quality-aware features from different luminance areas: 1) local entropy feature is extracted from the dark and bright areas to measure the information loss due to the overexposure or underexposure during the tone mapping process; 2) local colorfulness feature is extracted from the normal area to evaluate the reproduction of colors. With the consideration that the perception of image quality depends on the combined effects of the salient local distortion and global quality degradation, the global contrast feature is also calculated and integrated for better evaluation performance. Moreover, to take advantage of the hierarchical characteristic of the HVS, all features are calculated under a multi-resolution framework. Eventually, the extracted features are mapped into an objective quality score based on the random forest regression. The proposed metric is shown to outperform those state-of-the-art metrics according to extensive experiments conducted on two publicly available databases.
关键词： tone-mapped image,multi-resolution representation,Tone-mapping operators,random forest regression,luminance partition,human visual system
更新于2025-09-23 15:23:52
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Comparison of different non-invasive diagnostic techniques used for HMME-PDT in the treatment of port wine stains
摘要： Background: Hemoporfin-mediated photodynamic therapy (HMME-PDT) is an effective method for treating port wine stains (PWS). While, it still lacks methods to evaluate the treatment of HMME-PDT for PWS effectively and objectively. Objective: This study aimed to compare the value of different non-invasive diagnostic techniques used for HMME-PDT treatment evaluation in PWS. Methods: Thirty-one lesions of 22 patients with PWS were treated with HMME-PDT. Four non-invasive diagnostic techniques including VISIA-CRTM system, dermoscopy, high-frequency ultrasound (HFUS) and laser speckle imager (LSCI) were used to obtain standard radiographic data containing skin color, skin thickness, blood vessel morphology, blood vessel distribution and blood perfusion from lesions and normal skin surrounded before and after HMME-PDT. Results: The standard image pattern of VISIA-CRTM system showed color change of the lesions of PWS after HMME-PDT. RBX-red image of VISIA-CRTM system showed that erythema was highly aggregated even on invisible lesions at baseline but decreased after HMME-PDT. The erythema index reduced value d was related to the efficacy rating (γ=0.631, P＜0.05). Dermoscopy showed that the number of spot-like and irregular linear vessels increased correlated with increase of clinical classification. After HMME-PDT, vascular rupture was observed by dermoscopy. The response rate of lesions with vascular rupture was 100.00% (20/20). And the response rate of lesions without vascular rupture was 63.64% (7/11). Vascular rupture sign was correlated with better efficacy (P＜0.05). High-frequency ultrasound showed that dermis of PWS thickened and arranged loosely with scattered linear hypoechoic signal. After HMME-PDT, the dermal layer of the lesions became thinner with the linear hypoechoic signal decreased. The response rate of lesions with linear hypoechoic signal was 76.92% (10/13), and that without linear hypoechoic signal was 94.44% (17/18). The lesions without linear hypoechoic signal in dermis showed better efficacy (P＜0.05). In some lesions, Laser speckle contrast showed high blood perfusion signal in PWS lesions and a blood perfusion reduction after HMME-PDT. Conclusion: VISIA-CRTM system can be used to observe not only visible but also invisible lesions of PWS. Moreover, lesions fading after HMME-PDT treatment can be described objectively by VISIA-CRTM system. Dermoscopy played an important role in the clinical classification of PWS, including assessing vascular injury after HMME-PDT, guiding the adjustment of therapeutic dose, and selecting the end point of treatment. HFUS and LSCI can be both used to assist the treatment response evaluation of HMME-PDT.
关键词： dermoscopy,port-wine stains,laser speckle contrast imaging,hemoporfin-mediated photodynamic therapy,VISIA-CRTM system,high-frequency ultrasound
更新于2025-09-23 15:23:52
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[IEEE 2018 XIV International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE) - Novosibirsk, Russia (2018.10.2-2018.10.6)] 2018 XIV International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE) - Universal Control System of a Semiconductor Electric Energy Converter on Programmable Logic Devises
摘要： The article presents the results of the development of a universal control system for semiconductor power converters based on a programmable logic devices (PLD). As a result of the work done, shared functional modules for the various control systems of semiconductor converters were determined, the features of implementing modules on programmable logic were considered, and the algorithms for controlling converters on mathematical models were studied. The principal circuit diagram of the universal control system of the converter is synthesized on the basis of a combination of programmable logic devises and a microcontroller. The topologies of printed circuit boards and their layout in a single module of the universal control system of the converter are developed; the built-in microcontroller software was written and debugged in the assembler language. An experimental sample of the control system was made and its joint tests with a prototype of a low-power three-phase inverter equipped with a load simulator were carried out, oscillograms of control pulses and output voltage were obtained in various modes of inverter control.
关键词： digital control system,programmable logic device,algorithm,semiconductor power converter,model
更新于2025-09-23 15:23:52
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[IEEE 2018 Ubiquitous Positioning, Indoor Navigation and Location-Based Services (UPINLBS) - Wuhan (2018.3.22-2018.3.23)] 2018 Ubiquitous Positioning, Indoor Navigation and Location-Based Services (UPINLBS) - Image Processing Based Indoor Localization System for Assisting Visually Impaired People
摘要： Indoor localization or indoor positioning system is a known as a process of detecting position of any object or people inside a building or room by different sensory data collected from different devices using different techniques such as radio waves, magnetic fields, acoustic signals or other procedures. However, lacking of a standard localization system is still a very big concern. Solution of this issue can be very beneficial for people in many cases but it can be especially very beneficial for the visually impaired people. In this paper, an image processing based indoor localization system has been developed using OpenCV and Python by following color detection technique to detect position of the user with maximum accuracy and then location of user is determined by analyzing that location matrix. Location accuracy depends on the size of the matrix and successful identification of target color. Firebase real time database was added to the system which made real time operations between server and the user end device easier. To justify the proposed model, successful experiments were conducted in indoor environments as well and correct result was achieved each time by detecting accurate locations. This will be very advantageous to observe the fully or partially sightless people and guide them towards their destination and also to inspect them for their security purpose.
关键词： Color Segmentation,Indoor localization,Image Processing,Indoor positioning system,Wireless communication,Connected object detection
更新于2025-09-23 15:23:52
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Research on indocyanine green angiography for predicting postoperative hypoparathyroidism
摘要： Background: It may be critical to locate the parathyroid for surgeons during thyroidectomy or parathyroidectomy due to the significant function of the parathyroid in calcium balance. According to recent reports, the intrinsic fluorescence of the parathyroid has been found. There is some evidence supporting that new equipment can detect fluorescence via imaging technology. In this study, a newly-invented intraoperative fluorescence imaging system and indocyanine green dye were applied to detect the parathyroid glands and evaluate the vascularization of the parathyroid. The report is as follows. Methods: From May 1st to August 8st, 2018, 26 patients underwent total thyroidectomy in Zhuhai People’s Hospital and were recruited into our research. All identified parathyroid glands were scored visually from grade 0 to grade 2 according to the vascularity of the parathyroid before ICG angiography was performed. After ICG angiography, parathyroid glands were scored from score 0 to score 2 according to the FI. Results: Visual scores were significantly higher than ICG angiography scores. In the 22 patients with at least one parathyroid gland with an ICG score of 2, postoperative PTH levels were in the normal range. In the 4 patients with no parathyroid gland with an ICG score of 2, 2 of them developed transient hypoparathyroidism, with recovery on POD 7 for the first patient and after 3 months for the second one. Conclusion: This study has identified that the fluorescence imaging system applied with indocyanine green is a safe, easy and effective method to protect the parathyroid and predict postoperative hypoparathyroidism. Registration number: ChiCTR1800016864.
关键词： Fluorescence imaging system,Indocyanine green,Postoperative hypoparathyroidism.,Parathyroid
更新于2025-09-23 15:23:52
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Interference Suppression of Partially Overlapped Signals Using GSVD and Orthogonal Projection
摘要： In order to solve the problem in Automatic Identification System (AIS) that the signal in the target slot cannot be correctly received due to partial overlap of signals in adjacent time slots, the paper introduces a new criterion: maximum expected signal power (MESP) and proposes a novel beamforming algorithm based on generalized singular value decomposition (GSVD) and orthogonal projection. The algorithm employs GSVD to estimate the signal subspace, and adopts orthogonal projection to project the received signal onto the orthogonal subspace of the non-target signal. Then, beamforming technique is used to maximize the output power of the target signal on the basis of MESP. Theoretical analysis and simulation results show the effectiveness of the proposed algorithm.
关键词： blind beamforming,automatic identification system,partial overlapping,generalized singular value decomposition,orthogonal projection
更新于2025-09-23 15:23:52
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[Advanced Structured Materials] Materials Design and Applications II Volume 98 || Orientation of the Digital Model for SLA 3D Printing and Its Influence on the Accuracy of the Manufactured Physical Objects for Micro- and Nano Technologies
摘要： In modern mechanical engineering, there is increased need to find solutions for fast manufacturing of real prototypes. One of these is the fast-growing up-to-date CAD/CAM/CAE system enabling to create digital prototypes. Using CAD systems the conceptual design is analyzed and tested before producing the real prototype. This reduces the compliance costs for manufacturing of the physical models and tooling as well as the production time of the prototype is lessened several times. With the development of technology, and especially in medicine, it is necessary to produce prototypes that can be obtained relatively quickly and meet the requirements of accuracy. Rapid prototyping technologies have such capabilities that they can reproduce digital models with their manufacturer’s precision. To determine the accuracy of printing, a SLA system is used. To determine the accuracy of printing, a SLA system is used. One of the peculiarities of making a detail by this method is the appearance of distortions in the initial stage of construction at large rectilinear plots. In order to determine the minimum printing deviations, a strategy for printing prototype models at a different slope of 0°–90° was used. Patterns are made with coordinate networks, enabling post-print deviations to be evaluated by matching the digital model. The present study will be useful in developing prototype models for micro and nanotechnology in mechanical engineering and medicine, providing a solution for their optimal location with minimal deviations.
关键词： CAD system,Material for casting,Photopolymer,Micro model,SLA 3D printing
更新于2025-09-23 15:23:52