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Application of HRGS for forensic characterization of uranium oxides, pure uranium metals and uranium alloys

APPLIED RADIATION AND ISOTOPES 2021年 177卷 109910-109910页

作者： Burdeinyi, D. Kutnii, D. Levenets, V Turkin, A. Marks, N. Lindvall, R. Treinen, K. Natl Sci Ctr Kharkov Inst Phys & Technol UA-61108 Kharkov Ukraine Lawrence Livermore Natl Lab 7000 East AveL-231 Livermore CA 94551 USA

A nondestructive iterative method for uranium-bearing material characterization with HRGS developed earlier in Burdeinyi et al. (2020) is applied to determine matrix densities, uranium mass fraction and uranium isotope masses of uranium ore, UO2 and U3O8 powders, fuel elements in the form of UO2 microspheres, uranium metal and uranium alloys. It is shown that U3O8 powders with uranium mass fraction of about 84% can be distinguished from the powders of UO2 with uranium mass fraction of about 87%;uranium products in the form of liquid or loose powder with matrix density of 0.5-2.0 g/cm(3) can be distinguished from uranium products in the form of compacted fuel elements with matrix density of 6.0-10.0 g/cm(3) and from pure metal uranium and uranium alloys with matrix density of 14.0-19.0 g/cm(3). In fuel microspheres based on UO2 the uranium mass fraction 88.02% measured by HRGS is consistent, within the measurement uncertainties, with the results of isotope dilution mass spectrometry 87.76 +/- 0.64% and also is confirmed by X-ray diffraction technique. The uranium mass fraction of the uranium ore estimated as 0.08% by HRGS is consistent, within the measurement uncertainties, with the value 0.09 +/- 0.01% determined with WDXRF. Densities of two different uranium metal samples, estimated as 18.42 g/cm(3) and 19.33 g/cm(3) by HRGS are consistent with values 18.24 +/- 0.55 g/cm(3) and 18.86 +/- 0.59 g/cm(3), respectively, obtained by the gas pycnometry technique.

关键词： HRGS iterative algorithm Uranium oxide Uranium metal Uranium alloy Uranium mass fraction Matrix density Nuclear forensics IDMS WDXRF XRD

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Intelligent Reflecting Surface Assisted Non-Orthogonal Multiple Access

Intelligent Reflecting Surface Assisted Non-Orthogonal Multi...

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IEEE Wireless Communications and Networking Conference (IEEE WCNC)

作者： Yang, Gang Xu, Xinyue Liang, Ying-Chang Univ Elect Sci & Technol China Chengdu Peoples R China

ISBN: (纸本)9781728131061

Intelligent reflecting surface (IRS) is a new and disruptive technology to achieve spectrum-, energy, and cost-efficient wireless networks. In this paper, we consider an IRS-assisted non-orthogonal-multiple-access (NOMA) system in which a base station (BS) transmits superposed down-link signals to multiple users. A combined-channel-strength (CCS) based user ordering scheme is first proposed. In order to optimize the rate performance and ensure user fairness, we further maximize the minimum decoding signal-to-interference-plus-noise-ratio (i.e., equivalently the rate) of all users, by jointly optimizing the power allocation at the BS and the phase shifts at the IRS. However, the formulated problem is non-convex and difficult to be solved optimally. By leveraging the block coordinate descent and semidefinite relaxation techniques, an efficient algorithm is then proposed to obtain a suboptimal solution. Simulation results show that the IRS-assisted downlink NOMA system can enhance the rate performance significantly, compared to traditional NOMA without IRS and traditional orthogonal multiple access with/without IRS, and the rate degradation due to the IRS's finite phase resolution is slight.

关键词： Non-orthogonal multiple access intelligent reflecting surface rate optimization iterative algorithm

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Analysis on the stiffness iteration of segmental joints in segmental linings: Method and sensitivity analysis

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TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 2021年 115卷 104043-104043页

作者： Feng, Kun Zhang, Li Guo, Wenqi Yang, Renjie He, Chuan Zhang, Jingxuan Southwest Jiaotong Univ Key Lab Transportat Tunnel Engn Minist Educ Chengdu 610031 Peoples R China Southwest Jiaotong Univ China Japan RSC Struct Res Ctr Chengdu 610031 Peoples R China

In current structural analyses on segmental linings, the bending stiffness of segmental joints is usually treated as a constant, which results in a deviation in the calculated internal forces and deformation. In view of this, a finite element model of segmental linings is established using one ring and two half rings. An iterative algorithm is designed with a 3D curved surface of bending stiffness for the segmental joint, obtained from a series of full-scale tests under different axial force and bending moment cases. The rational convergence criteria for the iterative algorithm are recommended by evaluating the convergence efficiency of the iterative algorithm. Moreover, the influence of load magnitude and initial value of bending stiffness, as well as the changing laws of structural internal forces and deformation with the assembly angles, are presented and analyzed. The results show that with the same load, the convergence of the iterative algorithm in staggered-jointed assembly structures (STGS) is better than that of straight-jointed assembly structures (STRS), owing to its greater overall stiffness. The initial input value of bending stiffness has no effect on the convergence of the proposed iterative algorithm, and generally the convergence performance in STGS is better than that in STRS. In STRS, the bending moment is most sensitive to the changes of assembly angles, while in STGS the assembly angles have great influence on both the bending moment and structural displacement. Without the stiffness iteration, the maximum differences for maximum axial force, bending moment, and displacement under different assembly angle in STRS are 11.7%, 31.9% and 22.3%, respectively, and that differences in STGS are 10.4%, 59.3% and 35.1%, respectively. With the stiffness iterative method, the increase amplitude of the maximum axial force, the maximum bending moment, and the maximum displacement in STRS and STGS are 50.0%, 317.4%, 77.1% and 41.9%, 459.3%, 156.5%, respectivel

关键词： Shield tunnel Segmental joint Bending stiffness iterative algorithm Convergence performance

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Static output feedback negative imaginary controller synthesis with an H_∞ norm bound

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AUTOMATICA 2021年 126卷 109157-109157页

作者： Ren, Dingchao Xiong, Junlin Ho, Daniel W. C. Univ Sci & Technol China Dept Automat Hefei 230026 Peoples R China City Univ Hong Kong Dept Math Kowloon Hong Kong Peoples R China

A large number of practical systems can be modeled as negative imaginary (NI) systems. In this paper, we investigate the problem of static output feedback (SOF) NI controller design with H-infinity performance. Motivated by the two-stage framework for SOF stabilization, a sufficient condition is derived for the SOF controller synthesis. An iterative LMI-based algorithm is suggested to find an SOF controller. The algorithm consists of two stages: (1) finding an initial output injection controller;(2) computing a desired SOF controller. In addition, a numerical example is provided to verify the proposed method. (C) 2020 Published by Elsevier Ltd.

关键词： H-infinity control iterative algorithm Linear matrix inequality Negative imaginary system Static output feedback

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An iterative algorithm for the stability analysis of dynamic interval systems

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APPLIED NUMERICAL MATHEMATICS 2013年 69卷 73-77页

作者： Leng, Huinan Zhang, Qi E China Univ Sci & Technol Dept Math Shanghai 200237 Peoples R China Fudan Univ Sch Math Sci Shanghai 200433 Peoples R China

In this paper, a new iterative algorithm is proposed to analyze the stability of dynamic interval systems. Compared with existing researches, this algorithm takes much less computation time to obtain the superior of maximal eigenvalues and the inferior of minimal eigenvalues of a real interval matrix with real eigenvalues, under given precision. As a result, the stability of a dynamic interval system, which is determined by eigenvalues of its corresponding interval matrix, can be judged within a shorter time period. Furthermore, if the dynamic interval system is concluded to be stable, the output of our iterative algorithm also indicates the accurate maximal stability margin of this system. Finally, three numerical examples are given to demonstrate the applicability and effectiveness of this algorithm. (C) 2013 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： Stability analysis Dynamic interval systems Interval matrices iterative algorithm Stability margin

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RnR: A Software-Assisted Record-and-Replay Hardware Prefetcher 53

RnR: A Software-Assisted Record-and-Replay Hardware Prefetch...

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53rd Annual IEEE/ACM International Symposium on Microarchitecture (MICRO)

作者： Zhang, Chao Zeng, Yuan Shalf, John Guo, Xiaochen Lehigh Univ Bethlehem PA 18015 USA Lawrence Berkeley Natl Lab Berkeley CA USA

ISBN: (纸本)9781728173832

Applications with irregular memory access patterns do not benefit well from the memory hierarchy as applications that have good locality do. Relatively high miss ratio and long memory access latency can cause the processor to stall and degrade system performance. Prefetching can help to hide the miss penalty by predicting which memory addresses will be accessed in the near future and issuing memory requests ahead of the time. However, software prefetchers add instruction overhead, whereas hardware prefetchers cannot efficiently predict irregular memory access sequences with high accuracy. Fortunately, in many important irregular applications (e.g., iterative solvers, graph algorithms, and sparse matrix-vector multiplication), memory access sequences repeat over multiple iterations or program phases. When the patterns are long, a conventional spatial-temporal prefetcher can not achieve high prefetching accuracy, but these repeating patterns can be identified by programmers. In this work, we propose a software-assisted hardware prefetcher that focuses on repeating irregular memory access patterns for data structures that cannot benefit from conventional hardware prefetchers. The key idea is to provide a programming interface to record cache miss sequence on the first appearance of a memory access pattern and prefetch through replaying the pattern on the following repeats. The proposed Record-and-Replay (RnR) prefetcher provides a lightweight software interface so that the programmers can specify in the application code: 1) which data structures have irregular memory accesses, 2) when to start the recording, and 3) when to start the replay (prefetching). This work evaluated three irregular workloads with different inputs. For the evaluated workloads and inputs, the proposed RnR prefetcher can achieve on average 2.16x speedup for graph applications and 2.91 x speedup for an iterative solver with a sparse matrix-vector multiplication kernel. By leveraging the knowledge f

关键词： hardware prefetcher irregular memory access iterative algorithm

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Polar Code-Aided Frequency Offset Estimation algorithm in Satellite Covert Communication Carrier Synchronization 4

Polar Code-Aided Frequency Offset Estimation Algorithm in Sa...

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4th IEEE Information Technology, Networking, Electronic and Automation Control Conference (ITNEC)

作者： Wu, Jiayi Chen, Chaofan Bu, Xiangyuan Beijing Inst Technol Sch Informat & Elect Beijing Peoples R China

ISBN: (纸本)9781728143903

At present, covert satellite communication has become one of the most important application scenarios in the communication field. Due to various interferences and detections in space communication environment, satellite covert communications usually adopt short codes for channel coding, such as polar codes. However, polar coding method is highly sensitive to carrier synchronization error, and the performance of the satellite covert communication will degrade severely with the presence of carrier frequency offset. Therefore, carrier synchronization is a critical issue in the field of covert satellite communication. Existing carrier synchronization algorithms are mostly based on pilot assistance and have low spectrum utilization. To cope with the challenge of limit of spectrum in satellite communication and at the same time to guarantee a high communication quality, we propose a polar code-aided frequency offset estimation (PCAFOE) algorithm model in this paper. Based on the estimation indicator of RMSE, Monte Carlo simulations and corresponding analysis are presented. Compared with the traditional carrier synchronization algorithm, PCAFOE algorithm is demonstrated with higher estimation accuracy, which is able to effectively improve the carrier synchronization performance of covert satellite communication systems.

关键词： covert satellite communication carrier synchronization polar codes iterative algorithm

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Implementation and Numerical Evaluation for Multiplicative Algebraic Reconstruction Techniques 6

Implementation and Numerical Evaluation for Multiplicative A...

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Conference on Optical System Alignment, Tolerancing, and Verification XIII

作者： Aoyagi, Tomohiro Ohtsubo, Kouichi Aoyagi, Nobuo Toyo Univ Fac Informat Sci & Arts 2100 Kujirai Saitama 3508585 Japan

ISBN: (纸本)9781510638495;9781510638501

Multiplicative algebraic reconstruction techniques (MART) is one of the method of projections onto convex sets (POCS) for solving a system of simultaneous equation. The image reconstruction problem can be discretized and depends on seeking the inverse of some matrix. We apply the MART to image reconstruction problems and evaluate the image quality in computer simulations. It is showed that the error decreases with increasing the number of projections and the number of iterations. It is also showed that the error decreases with increasing the value of initial data.

关键词： image reconstruction MART POCS iterative algorithm tomography

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Numerical simulation for train-track-bridge dynamic interaction considering damage constitutive relation of concrete tracks

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ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING 2021年第3期21卷 116-116页

作者： Xu, Lei Yu, Zhiwu Shan, Zhi Cent South Univ Sch Civil Engn Shaoshan Rd 22 Changsha 410075 Peoples R China Natl Engn Lab High Speed Railway Construct Changsha 410075 Peoples R China

In this work, a novel and practical method is developed to depict the track slab damage and residual strain evolution, where the concrete damage constitutive relation of track slabs is considered within the train-track-bridge dynamics framework. A three-step strain method is presented to judge the load/unloading, compression/tension status of track slab elements ergodically, so that the damage condition and residual strain of track slabs can be determined. To improve the computational accuracy and efficiency, the combination of the matrix augment method and iterative solution algorithm is elucidated in detail. To validate the present model, the solutions among incremental solution, iterative solution, and non-iterative solution are firstly illustrated, and then experimental studies are performed to declare the effectiveness of this model in characterising strain/stress relation of concrete no matter in compression state or in tension state, and finally, other model results are also introduced to prove the effectiveness of this model. In the numerical studies, the damage distributions of track slabs in the longitudinal and lateral direction are presented, where the influence of track irregularities and track slab positions on the bridge is clarified, besides, the evolution of the damage and residual strain of a track slab subject to a moving train is revealed.

关键词： Train-track-bridge dynamic interaction Damage constitutive relation Stress strain status iterative algorithm

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Reconstruction of Compressed Sensing MRI: An Experimental Review among Priors- and Deep Learning- based algorithms 2

Reconstruction of Compressed Sensing MRI: An Experimental Re...

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2nd International Conference on Sustainable Technologies for Industry 4.0 (STI)

作者： Islam, Rafiqul Dhaka Univ Engn & Technol Dept Comp Sci & Engn Gazipur Bangladesh

ISBN: (纸本)9781665404891

Magnetic resonance imaging (MRI) is the most effective and reliable imaging process to visualize the internal organs of the human body for clinical purposes and medical research. Although MRI does not use any radiation effect, it takes a long time to acquire an MRI image that makes discomfort to the patients, especially children and persons who have anxiety. Compressed sensing (CS) is a recently used technique for allowing faster acquisition of MRI. Since CS generates random under-sampling k-space measurements due to allowing faster acquisition, a non-linear algorithm is required for reconstructing a perfect MRI image. In this work, a comparative study is performed among single priors-, combined priors-, and deep learning-based non-linear algorithms for the reconstruction of MRI from CS measurements. Experiments are conducted to perform a comparative study that shows the significant aspects of the algorithms in terms of visual quality and quantitative measurements compared with each other. The results of the experiment proved the superiority of the combined priors-based method when compared with the single priors- and deep learning-based method.

关键词： Compressed Sensing Magnetic Resonance Imaging Regularization Prior iterative algorithm Image reconstruction Deep Learning

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