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过滤筛选
- 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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Utility of PET/CT in diagnosis, staging, assessment of resectability and metabolic response of pancreatic cancer
摘要： Pancreatic cancer is one of the most common gastrointestinal tumors, with its incidence staying at a high level in both the United States and China. However, the overall 5-year survival rate of pancreatic cancer is still extremely low. Surgery remains the only potential chance for long-term survival. Early diagnosis and precise staging are crucial to make proper clinical decision for surgery candidates. Despite advances in diagnostic technology such as computed tomography (CT) and endoscopic ultrasound, diagnosis, staging and monitoring of the metabolic response remain a challenge for this devastating disease. Positron emission tomography/CT (PET/CT), a relatively novel modality, combines metabolic detection with anatomic information. It has been widely used in oncology and achieves good results in breast cancer, lung cancer and lymphoma. Its utilization in pancreatic cancer has also been widely accepted. However, the value of PET/CT in pancreatic disease is still controversial. Will PET/CT change the treatment strategy for potential surgery candidates? What kind of patients benefits most from this exam? In this review, we focus on the utility of PET/CT in diagnosis, staging, and assessment of resectability of pancreatic cancer. In addition, its ability to monitor metabolic response and recurrence after treatment will be emphasis of discussion. We hope to provide answers to the questions above, which clinicians care most about.
关键词： Staging,Pancreatic cancer,Metabolic response,Position emission tomography/computed tomography,Diagnosis
更新于2025-09-10 09:29:36
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Tuning phototactic robots with sensorial delays
摘要： The presence of a delay between sensing and reacting to a signal can determine the long-term behavior of autonomous agents whose motion is intrinsically noisy. In a previous work [Mijalkov, McDaniel, Wehr, and Volpe, Phys. Rev. X 6, 011008 (2016)], we have shown that sensorial delay can alter the drift and the position probability distribution of an autonomous agent whose speed depends on the illumination intensity it measures. In this work, we consider an agent whose speed and rotational diffusion both depend on the illumination intensity and are subject to two independent sensorial delays. Using theory, simulations, and experiments with a phototactic robot, we study the dependence of the drift and of the probability distribution of the robot’s position on the sensorial delays. In particular, the radial drift may have a positive as well as negative sign, and the position probability density peaks in different regions, depending on the choice of the model’s parameters. This not only generalizes previous work but also explores new phenomena resulting from the interaction between the two delay variables.
关键词： autonomous agents,phototactic robot,sensorial delay,rotational diffusion,position probability distribution
更新于2025-09-10 09:29:36
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Position Sensing and High Bandwidth Data Communication using Impact Ionization Engineered APD Arrays
摘要： Position sensing and high bandwidth data reception are functions typically performed by two separate detectors in conventional free space optical communication systems. In this letter, we report low excess noise, impact ionization engineered InAlAs/InGaAs avalanche photodiode arrays that can perform both functions simultaneously.
关键词： position sensitive detectors,Avalanche photodiodes,free-space optical communication,photodetectors
更新于2025-09-10 09:29:36
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Adaptive Beamforming with Sensor Position Errors Using Covariance Matrix Construction based on Subspace Bases Transition
摘要： This letter proposes a narrowband interference-plus-noise covariance matrix (INCM) based beamformer, which is robust with sensor position errors for linear array. First, using the subspace fitting and subspace orthogonality techniques, we estimate a set of angle-related bases for the signal-plus-interference subspace (SIS) by solving a joint optimization problem. Second, we obtain the bases transition matrix between the estimated angle-related bases and the orthogonal bases consisting of the dominant eigenvectors of the sample covariance matrix (SCM). The SCM can be expressed as a function of the angle-related bases and the bases transition matrix. We construct the INCM directly from the SIS by eliminating the component of the desired signal from the angle-related bases. Simulations and experimental results show that the proposed beamformer outperforms other tested beamformers in the presence of sensor position errors.
关键词： covariance matrix construction,Bases transition,sensor position error,robust adaptive beamforming
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Small Force Measurement at CMS/ITRI
摘要： This paper introduces the small force measurement system at micronewton level at Center for Measurement Standards, Industrial Technology Research Institute (CMS/ITRI). The construction of the system started in 2009 and completed in 2014. The force measurement system consists of three main parts: a monolithic flexure stage, a three planar electrodes capacitor and a digital controller. The three planar electrodes capacitor is utilized simultaneously as a position sensor and an electrostatic force generator. Accurate electrostatic force is generated by constantly adjusting and maintaining gap distances between three planar electrodes. The lowest force uncertainty was evaluated to be 4.7 nN. The previous results show that the relative standard uncertainty at 10 μN and 100 μN are 2.3 × 10?4 and 7.4 × 10?5, respectively. At current stage, the mass of mg level realized by this system has a slightly larger uncertainty than that obtained from traditional subdivision method. We discuss future works to further improve this system.
关键词： capacitive position sensing,Electrostatic force,microforce standard,mg realization
更新于2025-09-10 09:29:36
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Impact of alkyl chain branching positions on molecular packing and electron transport of dimeric perylenediimide derivatives
摘要： Side chains play a critical role in tuning intermolecular interaction and charge transport in organic semiconductors. Here, we have systematically investigated the impact of branching positions of the alkyl side chains on the molecular packing and electron transport properties of a series of bay-linked dimeric perylenediimide (PDI) derivatives by atomistic molecular dynamics simulations in combination with charge transfer rate theory and kinetic Monte Carlo simulations. The results show that despite of different branching positions of the alkyl chains, π –π stacking is effectively inhibited for all the dimeric PDI derivatives. As the branching position moves away from the PDI backbone, the appearance of the alkyl atoms around the PDI backbone will first decrease and then increase. Correspondingly, the short contacts between the PDI moieties are first enhanced and then reduced. In particular, when the branching position is at the third carbon atom, the intermolecular connectivity becomes the most effective and the electron mobility is significantly increased by 2 times.
关键词： Electron mobility,Branching position,Perylenediimide,Molecular packing
更新于2025-09-10 09:29:36
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Effect of measurement position on prediction of apple soluble solids content (SSC) by an on-line near-infrared (NIR) system
摘要： Near infrared spectroscopy has been widely applied in the area of rapid determination for fruits’ internal qualities. Therefore, an on-line near-infrared detection system was established to predict the SSC of apples in this study. Due to random measurement positions of apples, negative influences will be exerted on the performance of prediction models. With the aim of learning more about these influences and also compensating for them, spectra were taken at different measurement positions in the present work, including six fixed positions and a random position. Besides, the relations between these positions were investigated as well. It is also found that when the concave surfaces at apple’s calyx and stem interfered with the light path in the detection system, model’s robustness and accuracy would be deteriorated. At last, average and global spectra were used to build prediction models with comparison purpose. The optimal prediction model was established by the average spectra of seven measurement positions (RMSEC 0.356%; rc 0.947; RMSEP 0.370%; rp 0.906), which was superior to results in many previous studies. Last but not least, several suggestions on compensation for these influences were made to improve the model performance in some practical applications.
关键词： Apple,Soluble solids content,On-line,Measurement position,Near-infrared
更新于2025-09-10 09:29:36
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Space Navigation by X-Ray Pulsars
摘要： This review considers the problem of autonomously determining the position of a spacecraft in space based on the analysis of pulses emitted by X-ray pulsars. The characteristics of the prospective equipment and lists of pulsar candidates for reference sources are given. The navigation algorithm and resulting accuracy characteristics are substantiated.
关键词： integral pulse,spatial position,pulsars
更新于2025-09-10 09:29:36
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High Precision Position Measurement Method for Laguerre-Gaussian Beams Using a Quadrant Detector
摘要： In this paper, we propose a new method to improve the position measurement accuracy for Laguerre-Gaussian beams on a quadrant detector (QD). First, the error effects of the detector diameter and the gap size are taken into account, and the position error compensation factor is introduced into the conventional formula. Then, in order to reduce the number of parameters, the concept of effective radius is proposed. Thus, a new analytical expression is obtained with a best fit using the least square method. It is verified by simulation that this approach can reduce the maximum error by 97.4% when the beam radius is 0.95 mm; meanwhile, the root mean square errors under different radii are all less than 0.004 mm. The results of simulation show that the new method could effectively improve the accuracy of the QD measurement for different radii. Therefore, the new method would have a good prospect in the engineering practice of beam position measurements.
关键词： quadrant detector,detection,Laguerre-Gaussian beams,effective radius,position measurement method,least square method
更新于2025-09-10 09:29:36
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Evaluation of the readout electronics based on the center of gravity method for position sensitive radiation detection
摘要： In the application of position sensitive radiation detection, the center of gravity method is often used to obtain better spatial resolution. In order to obtain the resolution degradation caused by the readout electronics, an evaluation method is put forward in this paper. The principle of the method is to simulate the signal distribution on sense wires of the MWPC (Multiwire Proportional Chamber) detector. The evaluation software quantizes the simulated data and drives the digital to analog converter to generate test signals. The readout electronics is evaluated with these stimulus signals according to the readout scale. An evaluation board based on this method is implemented. Tests are carried out in the laboratory to evaluate a readout circuit for the MWPC detector. The position resolution contributed by the electronics is better than 15 μm when the swtiching frenquency of the switch array is 12.5 MHz. The test results proved that the evaluation method is correct and practical. It can greatly simplify the evaluation of the readout electronics.
关键词： position sensitive radiation detection,center of gravity method,MWPC detector,spatial resolution,readout electronics
更新于2025-09-10 09:29:36