检索结果-内蒙古大学图书馆

Machine learning techniques in searches for t(t)over-barh in the h → b(b)over-bar decay channel

JOURNAL OF INSTRUMENTATION 2017年第4期12卷 P04014-P04014页

作者： Santos, R. Nguyen, M. Webster, J. Ryu, S. Adelman, J. Chekanov, S. Zhou, J. Northern Illinois Univ Dept Comp Sci 1425 W Lincoln Hwy De Kalb IL 60115 USA Northern Illinois Univ Dept Phys 1425 W Lincoln Hwy De Kalb IL 60115 USA Argonne Natl Lab 9700 S Cass Ave Lemont IL USA

Study of the production of pairs of top quarks in association with a Higgs boson is one of the primary goals of the Large Hadron Collider over the next decade, as measurements of this process may help us to understand whether the uniquely large mass of the top quark plays a special role in electroweak symmetry breaking. Higgs bosons decay predominantly to b (b) over bar, yielding signatures for the signal that are similar to t (t) over bar + jets with heavy flavor. Though particularly challenging to study due to the similar kinematics between signal and background events, such final states (t (t) over barb (b) over bar) are an important channel for studying the top quark Yukawa coupling. This paper presents a systematic study of machine learning (ML) methods for detecting t (t) over barh in the h -> b (b) over bar decay channel. Among the eight ML methods tested, we show that two models, extreme gradient boosted trees and neural network models, outperform alternative methods. We further study the effectiveness of ML algorithms by investigating the impact of feature set and data size, as well as the structure of the models. While extended feature set and larger training sets expectedly lead to improvement of performance, shallow models deliver comparable or better performance than their deeper counterparts. Our study suggests that ensembles of trees and neurons, not necessarily deep, work effectively for the problem of t (t) over barh detection.

关键词： Analysis and statistical methods data processing methods

来源：评论

学校读者我要写书评

暂无评论

Electrocardiogram signal denoising based on empirical mode decomposition technique: an overview

引用

JOURNAL OF INSTRUMENTATION 2017年第3期12卷 03010-03010页

作者： Han, G. Lin, B. Xu, Z. Fuzhou Univ Sch Mech Engn & Automat 2 Xueyuan Rd Fuzhou Fujian Peoples R China

Electrocardiogram (ECG) signal is nonlinear and non-stationary weak signal which reflects whether the heart is functioning normally or abnormally. ECG signal is susceptible to various kinds of noises such as high/low frequency noises, powerline interference and baseline wander. Hence, the removal of noises from ECG signal becomes a vital link in the ECG signal processing and plays a significant role in the detection and diagnosis of heart diseases. The review will describe the recent developments of ECG signal denoising based on Empirical Mode Decomposition (EMD) technique including high frequency noise removal, powerline interference separation, baseline wander correction, the combining of EMD and Other methods, EEMD technique. EMD technique is a quite potential and prospective but not perfect method in the application of processing nonlinear and non-stationary signal like ECG signal. The EMD combined with other algorithms is a good solution to improve the performance of noise cancellation. The pros and cons of EMD technique in ECG signal denoising are discussed in detail. Finally, the future work and challenges in ECG signal denoising based on EMD technique are clarified.

关键词： data processing methods Image reconstruction in medical imaging Image filtering data acquisition concepts

来源：评论

学校读者我要写书评

暂无评论

An innovative method to reduce count loss from pulse pile-up in a photon-counting pixel for high flux X-ray applications

引用

JOURNAL OF INSTRUMENTATION 2017年第3期12卷 03006-03006页

作者： Lee, D. Lim, K. Park, K. Lee, C. Alexander, S. Cho, G. Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn 291 Daehak Ro Taejon 305701 South Korea Dept Nucl Engn POB 127788 Abu Dhabi U Arab Emirates

In this study, an innovative fast X-ray photon-counting pixel for high X-ray flux applications is proposed. A computed tomography system typically uses X-ray fluxes up to 10(8) photons/mm(2)/sec at the detector and thus a fast read-out is required in order to process individual X-ray photons. Otherwise, pulse pile-up can occur at the output of the signal processing unit. These superimposed signals can distort the number of incident X-ray photons leading to count loss. To minimize such losses, a cross detection method was implemented in the photon-counting pixel. A maximum count rate under X-ray tube voltage of 90 kV was acquired which reflect electrical test results of the proposed photon counting pixel. A maximum count of 780 kcps was achieved with a conventional photon-counting pixel at the pulse processing time of 500 ns, which is the time for a pulse to return to the baseline from the initial rise. In contrast, the maximum count of about 8.1 Mcps was achieved with the proposed photon-counting pixel. From these results, it was clear that the maximum count rate was increased by approximately a factor 10 times by adopting the cross detection method. Therefore, it is an innovative method to reduce count loss from pulse pile-up in a photon-counting pixel while maintaining the pulse processing time.

关键词： Electronic detector readout concepts (solid-state) data processing methods Detector design and construction technologies and materials Solid state detectors

来源：评论

学校读者我要写书评

暂无评论

Basis material decomposition method for material discrimination with a new spectrometric X-ray imaging detector

引用

JOURNAL OF INSTRUMENTATION 2017年第8期12卷

作者： Brambilla, A. Gorecki, A. Potop, A. Paulus, C. Verger, L. Univ Grenoble Alpes CEA LETI DTBS LDET F-38000 Grenoble France

Energy sensitive photon counting X-ray detectors provide energy dependent information which can be exploited for material identification. The attenuation of an X-ray beam as a function of energy depends on the effective atomic number Zeff and the density. However, the measured attenuation is degraded by the imperfections of the detector response such as charge sharing or pile-up. These imperfections lead to non-linearities that limit the benefits of energy resolved imaging. This work aims to implement a basis material decomposition method which overcomes these problems. Basis material decomposition is based on the fact that the attenuation of any material or complex object can be accurately reproduced by a combination of equivalent thicknesses of basis materials. Our method is based on a calibration phase to learn the response of the detector for different combinations of thicknesses of the basis materials. The decomposition algorithm finds the thicknesses of basis material whose spectrum is closest to the measurement, using a maximum likelihood criterion assuming a Poisson law distribution of photon counts for each energy bin. The method was used with a ME100 linear array spectrometric X-ray imager to decompose different plastic materials on a Polyethylene and Polyvinyl Chloride base. The resulting equivalent thicknesses were used to estimate the effective atomic number Zeff. The results are in good agreement with the theoretical Zeff, regardless of the plastic sample thickness. The linear behaviour of the equivalent lengths makes it possible to process overlapped materials. Moreover, the method was tested with a 3 materials base by adding gadolinium, whose K-edge is not taken into account by the other two materials. The proposed method has the advantage that it can be used with any number of energy channels, taking full advantage of the high energy resolution of the ME100 detector. Although in principle two channels are sufficient, experimental measurements show t

关键词： data processing methods Detection of explosives Medical-image reconstruction methods and algorithms computer-aided diagnosis

来源：评论

学校读者我要写书评

暂无评论

The Thomson scattering diagnostic at Wendelstein 7-X and its performance in the first operation phase

引用

JOURNAL OF INSTRUMENTATION 2017年第10期12卷 P10004-P10004页

作者： Bozhenkov, S. A. Beurskens, M. Dal Molin, A. Fuchert, G. Pasch, E. Stoneking, M. R. Hirsch, M. Hoefel, U. Knauer, J. Svensson, J. Mora, H. Trimino Wolf, R. C. Max Planck Inst Plasma Phys D-17491 Greifswald Germany Univ Milano Bicocca Milan Italy Lawrence Univ Appleton WI 54912 USA

The optimized stellarator Wendelstein 7-X started operation in December 2015 with a 10 week limiter campaign. Divertor experiments will begin in the second half of 2017. The W7-X Thomson scattering system is an essential diagnostic for electron density and temperature profiles. In this paper the Thomson scattering diagnostic is described in detail, including its design, calibration, data evaluation and first experimental results. Plans for further development are also presented. The W7-X Thomson system is a Nd:YAGsetup with up to five lasers, two sets of light collection lenses viewing the entire plasma cross-section, fiber bundles and filter based polychromators. To reduce hardware costs, two or three scattering volumes are measured with a single polychromator. The relative spectral calibration is carried out with the aid of a broadband supercontinuum light source. The absolute calibration is performed by observing Raman scattering in nitrogen. The electron temperatures and densities are recovered by Bayesian modelling. In the first campaign, the diagnostic was equipped for 10 scattering volumes. It provided temperature profiles comparable to those measured using an electron cyclotron emission diagnostic and line integrated densities within 10% of those from a dispersion interferometer.

关键词： Plasma diagnostics - interferometry, spectroscopy and imaging data processing methods

来源：评论

学校读者我要写书评

暂无评论

NUISANCE: a neutrino cross-section generator tuning and comparison framework

引用

JOURNAL OF INSTRUMENTATION 2017年第1期12卷 01016-01016页

作者： Stowell, P. Wret, C. Wilkinson, C. Pickering, L. Cartwright, S. Hayato, Y. Mahn, K. McFarland, K. S. Sobczyk, J. Terri, R. Thompson, L. Wascko, M. O. Uchida, Y. Univ Sheffield Dept Phys & Astron Sheffield S Yorkshire England Imperial Coll London Dept Phys London England Univ Bern Albert Einstein Ctr Fundamental Phys High Energy Phys Lab Bern Switzerland Univ Tokyo Todai Inst Adv Study Kavli Inst Phys & Math Universe WPI Kashiwa Chiba Japan Univ Tokyo Inst Cosm Ray Res Kamioka Observ Kamioka Akita Japan Michigan State Univ Dept Phys & Astron E Lansing MI 48824 USA Univ Rochester Dept Phys & Astron Rochester NY 14627 USA Univ Wroclaw Inst Theoret Phys Wroclaw Poland Queen Mary Univ London Sch Phys & Astron London England

NUISANCE is an open source C++ framework which facilitates detailed studies of neutrino interaction cross- section models implemented in Monte Carlo neutrino event generators. It provides a host of automated methods to perform comparisons of multiple generators to published cross- section measurements and each other. External reweighting libraries are used to allow the end- user to evaluate the impact of model parameters variations in the generators with data, or to tune the generator predictions to arbitrary dataset combinations. The design is modular and focusses on ease- of- use to allow new datasets and more generators to be added without requiring detailed understanding of the entire NUISANCE package. We discuss the motivation for the NUISANCE framework and suggested usage cases, alongside a description of its core structure.

关键词： Software architectures (event data models, frameworks and databases) Analysis and statistical methods Simulation methods and programs data processing methods

来源：评论

学校读者我要写书评

暂无评论

Deuterium charge exchange recombination spectroscopy from the top of the pedestal to the scrape off layer in H-mode plasmas

引用

JOURNAL OF INSTRUMENTATION 2017年第10期12卷

作者： Haskey, S. R. Grierson, B. A. Stagner, L. Burrell, K. H. Chrystal, C. Groebner, R. J. Ashourvan, A. Pablant, N. A. Princeton Plasma Phys Lab POB 451 Princeton NJ 08543 USA Gen Atom Co POB 85608 San Diego CA 92186 USA Univ Calif Irvine Irvine CA 92697 USA

Recent completion of the thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on DIII-D [J.L. Luxon, Nucl. Fusion 42 (2002) 614] enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. Sixteen sightlines cover the core of the plasma and another sixteen are densely packed towards the edge, providing high resolution measurements of the pedestal and steep gradient edge region of H-mode plasmas. The complexities of the D-alpha spectrum require fitting with a comprehensive model, as well as using iterative collisional radiative modeling to determine the underlying thermal deuterium ion properties. Large differences in the structure and magnitude of impurity (C6+) and main-ion (D+) toroidal rotation profiles are seen in the H-mode pedestal. Additionally the D+ temperature can be half the value of the C6+ temperature at the separatrix and shows more of a pedestal structure. Typically only the impurity properties are measured and the main-ion properties are either assumed to be the same, or inferred using neoclassical models, which require validation in the steep gradient region. These measured differences have implications for transport model validation, intrinsic rotation studies, pedestal stability, and the boundary conditions for scrape off layer and plasma material interactions studies.

关键词： Plasma diagnostics - charged-particle spectroscopy Analysis and statistical methods data processing methods

来源：评论

学校读者我要写书评

暂无评论

Fast GPU-based absolute intensity determination for energy-dispersive X-ray Laue diffraction

引用

JOURNAL OF INSTRUMENTATION 2016年第1期11卷 T01001-T01001页

作者： Alghabi, F. Send, S. Schipper, U. Abboud, A. Pietsch, U. Kolb, A. Univ Siegen Inst Vis & Graph Holderlinstr 3 D-57076 Siegen Germany Univ Siegen Solid State Phys Walter Flex Str 3 D-57072 Siegen Germany

This paper presents a novel method for fast determination of absolute intensities in the sites of Laue spots generated by a tetragonal hen egg-white lysozyme crystal after exposure to white synchrotron radiation during an energy-dispersive X-ray Laue diffraction experiment. The Laue spots are taken by means of an energy-dispersive X-ray 2D pnCCD detector. Current pnCCD detectors have a spatial resolution of 384 x 384 pixels of size 75 x 75 mu m(2) each and operate at a maximum of 400 Hz. Future devices are going to have higher spatial resolution and frame rates. The proposed method runs on a computer equipped with multiple Graphics processing Units (GPUs) which provide fast and parallel processing capabilities. Accordingly, our GPU-based algorithm exploits these capabilities to further analyse the Laue spots of the sample. The main contribution of the paper is therefore an alternative algorithm for determining absolute intensities of Laue spots which are themselves computed from a sequence of pnCCD frames. Moreover, a new method for integrating spectral peak intensities and improved background correction, a different way of calculating mean count rate of the background signal and also a new method for n-dimensional Poisson fitting are presented. We present a comparison of the quality of results from the GPU-based algorithm with the quality of results from a prior (base) algorithm running on CPU. This comparison shows that our algorithm is able to produce results with at least the same quality as the base algorithm. Furthermore, the GPU-based algorithm is able to speed up one of the most time-consuming parts of the base algorithm, which is n-dimensional Poisson fitting, by a factor of more than 3. Also, the entire procedure of extracting Laue spots' positions, energies and absolute intensities from a raw dataset of pnCCD frames is accelerated by a factor of more than 3.

关键词： data processing methods Pattern recognition, cluster finding, calibration and fitting methods Analysis and statistical methods

来源：评论

学校读者我要写书评

暂无评论

Characterization and optimization of images acquired by a compact soft X-ray microscope based on a double stream gas-puff target source

引用

JOURNAL OF INSTRUMENTATION 2016年第4期11卷 C04003-C04003页

作者： Torrisi, A. Wachulak, P. Nawaz, M. Fahad Bartnik, A. Wegrzynski, L. Jancarek, A. Fiedorowicz, H. Mil Univ Technol Inst Optoelect Kaliskiego 2 Str PL-00908 Warsaw Poland Czech Tech Univ Fac Nucl Sci & Phys Engn Brehova 7 CR-11519 Prague 1 Czech Republic

Using a table-top size soft X-ray (SXR) microscope, based on a laser plasma source with a double stream gas-puff target and a Fresnel zone plate objective, series of images of test samples were acquired. Characterization and optimization of the acquisition parameters were studied and evaluated in terms of signal to noise ratio (SNR). Conclusions for the optimization of SXR imaging were reached. Similar SNR measurements might be performed to characterize other SXR imaging systems as well. Software enabling live calculation of the SNR during the image acquisition might be introduced in future in the compact imaging systems for optimal image acquisition or for benchmarking purposes.

关键词： data processing methods Optics Inspection with x-rays Interaction of radiation with matter

来源：评论

学校读者我要写书评

暂无评论

Neutron radiography as a non-destructive method for diagnosing neutron converters for advanced thermal neutron detectors

引用

JOURNAL OF INSTRUMENTATION 2016年第3期11卷 C03033-C03033页

作者： Muraro, A. Albani, G. Cippo, E. Perelli Croci, G. Angella, G. Birch, J. Cazzaniga, C. Caniello, R. Dell'Era, F. Ghezzi, F. Grosso, G. Hall-Wilton, R. Hoglund, C. Hultman, L. Schimdt, S. Robinson, L. Rebai, M. Salvato, G. Tresoldi, D. Vasi, C. Tardocchi, M. IFP CNR Ist Fis Plasma P Caldirola Via Cozzi 53 Milan Italy Univ Milano Bicocca Dipartimento Fis Piazza Sci 3 Milan Italy IENI CNR Via Cozzi 53 Milan Italy Linkoping Univ Dept Phys Chem & Biol IFM Thin Film Phys Div SE-58183 Linkoping Sweden STFC Rutherford Appleton Lab ISIS Didcot Oxon England European Spallat Source ESS ERIC Tunavagen 24 S-22363 Lund Sweden IPCF CNR Ist Proc Chim Fis Viale Ferdinando Stagno dAlcontres 37 Messina Italy

Due to the well-known problem of He-3 shortage, a series of different thermal neutron detectors alternative to helium tubes are being developed, with the goal to find valid candidates for detection systems for the future spallation neutron sources such as the European Spallation Source (ESS). A possible He-3-free detector candidate is a charged particle detector equipped with a three dimensional neutron converter cathode (3D-C). The 3D-C currently under development is composed by a series of alumina (Al2O3) lamellas coated by 1 mu m of B-10 enriched boron carbide (B4C). In order to obtain a good characterization in terms of detector efficiency and uniformity it is crucial to know the thickness, the uniformity and the atomic composition of the B4C neutron converter coating. In this work a non-destructive technique for the characterization of the lamellas that will compose the 3D-C was performed using neutron radiography. The results of these measurements show that the lamellas that will be used have coating uniformity suitable for detector applications. This technique (compared with SEM, EDX, ERDA, XPS) has the advantage of being global (i.e. non point-like) and non-destructive, thus it is suitable as a check method for mass production of the 3D-C elements.

关键词： Inspection with neutrons Neutron radiography Image filtering data processing methods

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：