Study of event reconstruction algorithm for a large-scale Si/CdTe multilayer Compton camera

Instruments ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 35
Author(s):  
Adam Lowe ◽  
Krishanu Majumdar ◽  
Konstantinos Mavrokoridis ◽  
Barney Philippou ◽  
Adam Roberts ◽  
...  

The ARIADNE Experiment, utilising a 1-ton dual-phase Liquid Argon Time Projection Chamber (LArTPC), aims to develop and mature optical readout technology for large scale LAr detectors. This paper describes the characterisation, using cosmic muons, of a Timepix3-based camera mounted on the ARIADNE detector. The raw data from the camera are natively 3D and zero suppressed, allowing for straightforward event reconstruction, and a gallery of reconstructed LAr interaction events is presented. Taking advantage of the 1.6 ns time resolution of the readout, the drift velocity of the ionised electrons in LAr was determined to be 1.608 ± 0.005 mm/μs at 0.54 kV/cm. Energy calibration and resolution were determined using through-going muons. The energy resolution was found to be approximately 11% for the presented dataset. A preliminary study of the energy deposition (dEdX) as a function of distance has also been performed for two stopping muon events, and comparison to GEANT4 simulation shows good agreement. The results presented demonstrate the capabilities of this technology, and its application is discussed in the context of the future kiloton-scale dual-phase LAr detectors that will be used in the DUNE programme.


2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Ilja Merunka ◽  
Andrea Massa ◽  
David Vrba ◽  
Ondrej Fiser ◽  
Marco Salucci ◽  
...  

In this work, a prototype of a laboratory microwave imaging system suitable to methodically test the ability to image, detect, and classify human brain strokes using microwave technology is presented. It consists of an antenna array holder equipped with ten newly developed slot bowtie antennas, a 2.5 D reconfigurable and replaceable human head phantom, stroke phantoms, and related measuring technology and software. This prototype was designed to allow measurement of a complete S-matrix of the antenna array. The reconfigurable and replaceable phantom has currently 23 different predefined positions for stroke phantom placement. This setting allows repeated measurements for the stroke phantoms of different types, sizes/shapes, and at different positions. It is therefore suitable for large-scale measurements with high variability of measured data for stroke detection and classification based on machine learning methods. In order to verify the functionality of the measuring system, S-parameters were measured for a hemorrhagic phantom sequentially placed on 23 different positions and distributions of dielectric parameters were reconstructed using the Gauss-Newton iterative reconstruction algorithm. The results correlate well with the actual position of the stroke phantom and its type.


2016 ◽  
Vol 675 (4) ◽  
pp. 042045
Author(s):  
D E Philippov ◽  
V N Belyaev ◽  
P Zh Buzhan ◽  
A L Ilyin ◽  
E V Popova ◽  
...  

2021 ◽  
Author(s):  
Chaolong Ying ◽  
Jing Liu ◽  
Kai Wu ◽  
Chao Wang

Currently, the problem of uncovering complex network structure and dynamics from time series is prominent in many fields. Despite the recent progress in this area, reconstructing large-scale networks from limited data remains a tough problem. Existing works treat connections of nodes as continuous values, leaving a challenge of setting a proper cut-off value to distinguish whether the connections exist or not. Besides, their performances on large-scale networks are far from satisfactory. Considering the reconstruction error and sparsity as two objectives, this paper proposes a subspace learning based evolutionary multiobjective network reconstruction algorithm, termed as SLEMO-NR, to solve the aforementioned problems. In the evolutionary process, we assume that binary-coded individuals obey the Bernoulli distribution and can use the probability and natural parameter as the alternative representations. Moreover, our approach utilizes the logistic principal component analysis (LPCA) to learn a subspace containing the features of network structure. The offspring solutions are generated in the learned subspace and then can be mapped back to the original space via LPCA. Benefitting from the alternative representations, a preference-based local search operator is proposed to concentrate on finding solutions approximate to the true sparsity. The experimental results on synthetic networks and six real-world networks demonstrate that, due to the well-learned network structure subspace and the preference-based strategy, our approach is effective in reconstructing large-scale networks compared to six existing methods.


F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1521 ◽  
Author(s):  
Brian C. Ross ◽  
James C. Costello

We previously published a method that infers chromosome conformation from images of fluorescently-tagged genomic loci, for the case when there are many loci labeled with each distinguishable color. Here we build on our previous work and improve the reconstruction algorithm to address previous limitations. We show that these improvements 1) increase the reconstruction accuracy and 2) allow the method to be used on large-scale problems involving several hundred labeled loci. Simulations indicate that full-chromosome reconstructions at 1/2 Mb resolution are possible using existing labeling and imaging technologies. The updated reconstruction code and the script files used for this paper are available at: https://github.com/heltilda/align3d.


Geophysics ◽  
1996 ◽  
Vol 61 (2) ◽  
pp. 570-583 ◽  
Author(s):  
Jerry M. Harris ◽  
Guan Y. Wang

Diffraction tomography was originally formulated for a constant velocity background medium. A variable background medium, e.g., layered, with embedded finer scale heterogeneities is a more practical model for subsurface reservoirs than the uniform background. The variable background of large scale variations may be determined from well logs or transmission tomography. To image the finer scale heterogeneities, we have developed a Fourier diffraction back‐propagation method for point sources in a layered background. The method is based on the normal mode solution to the acoustic wave equation in cylindrical coordinates. The Fourier spectrum of the scattered fields is first decomposed into contributions from different layers. Then, a selection rule is applied to sort out the heterogeneity spectrum of the individual layers. The selection rule relates the scattered field in diffraction space to the spectrum of the heterogeneities, i.e., a Fourier diffraction theorem for layered media. The theorem differs from its counterpart for a uniform background medium by a matrix filter that reduces to unity as the stratification degenerates to a uniform background. A reconstruction algorithm based on this theorem is implemented and tested for an arbitrary layered background. The theory deals directly with point sources; therefore, the resulting algorithm does not require application of the “2.5-D correction” to field data as required in previously published diffraction tomography algorithms. Results obtained for both synthetic and field data demonstrate that an inversion with spatial resolution on the order of a wavelength can be achieved for crosswell data. The computations involved are much more efficient than those of traveltime tomography or crosswell migration. Unlike migration or CDP mapping, the diffraction tomography algorithm provides quantitative estimates for fine scale velocity.


2018 ◽  
Vol 31 (11) ◽  
pp. 4403-4427 ◽  
Author(s):  
Nan Chen ◽  
Andrew J. Majda ◽  
C. T. Sabeerali ◽  
R. S. Ajayamohan

Abstract The authors assess the predictability of large-scale monsoon intraseasonal oscillations (MISOs) as measured by precipitation. An advanced nonlinear data analysis technique, nonlinear Laplacian spectral analysis (NLSA), is applied to the daily precipitation data, resulting in two spatial modes associated with the MISO. The large-scale MISO patterns are predicted in two steps. First, a physics-constrained low-order nonlinear stochastic model is developed to predict the highly intermittent time series of these two MISO modes. The model involves two observed MISO variables and two hidden variables that characterize the strong intermittency and random oscillations in the MISO time series. It is shown that the precipitation MISO indices can be skillfully predicted from 20 to 50 days in advance. Second, an effective and practical spatiotemporal reconstruction algorithm is designed, which overcomes the fundamental difficulty in most data decomposition techniques with lagged embedding that requires extra information in the future beyond the predicted range of the time series. The predicted spatiotemporal patterns often have comparable skill to the MISO indices. One of the main advantages of the proposed model is that a short (3 year) training period is sufficient to describe the essential characteristics of the MISO and retain skillful predictions. In addition, both model statistics and prediction skill indicate that outgoing longwave radiation is an accurate proxy for precipitation in describing the MISO. Notably, the length of the lagged embedding window used in NLSA is crucial in capturing the main features and assessing the predictability of MISOs.


Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4349 ◽  
Author(s):  
Tian Shi ◽  
Fei Mei ◽  
Jixiang Lu ◽  
Jinjun Lu ◽  
Yi Pan ◽  
...  

With the refinement and intelligence of power system optimal dispatching, the widespread adoption of advanced grid applications that consider the safety and economy of power systems, and the massive access of distributed energy resources, the requirement for bus load prediction accuracy is continuously increasing. Aiming at the volatility brought about by the large-scale access of new energy sources, the adaptability to different forecasting horizons and the time series characteristics of the load, this paper proposes a phase space reconstruction (PSR) and deep belief network (DBN)-based very short-term bus load prediction model. Cross-validation is also employed to optimize the structure of the DBN. The proposed PSR-DBN very short-term bus load forecasting model is verified by applying the real measured load data of a substation. The results prove that, when compared to other alternative models, the PSR-DBN model has higher prediction accuracy and better adaptability for different forecasting horizons in the case of high distributed power penetration and large fluctuation of bus load.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Craig T. Russell ◽  
Pedro P. Vallejo Ramirez ◽  
Eric Rees

AbstractWe present a tomographic reconstruction algorithm (flOPT), which is applied to Optical Projection Tomography (OPT) images, that is robust to mechanical jitter and systematic angular and spatial drift. OPT relies on precise mechanical rotation and is less mechanically stable than large-scale computer tomography (CT) scanning systems, leading to reconstruction artefacts. The algorithm uses multiple (5+) tracked fiducial beads to recover the sample pose and the image rays are then back-projected at each orientation. The quality of the image reconstruction using the proposed algorithm shows an improvement when compared to the Radon transform. Moreover, when adding a systematic spatial and angular mechanical drift, the reconstruction shows a significant improvement over the Radon transform.


2015 ◽  
Vol 40 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Young-Su Kim ◽  
Jin Hyung Park ◽  
Hwa Youn Cho ◽  
Jae Hyeon Kim ◽  
Heungrok Kwon ◽  
...  

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