373 research outputs found
Improved method for phase wraps reduction in profilometry
In order to completely eliminate, or greatly reduce the number of phase wraps
in 2D wrapped phase map, Gdeisat et al. proposed an algorithm, which uses
shifting the spectrum towards the origin. But the spectrum can be shifted only
by an integer number, meaning that the phase wraps reduction is often not
optimal. In addition, Gdeisat's method will take much time to make the Fourier
transform, inverse Fourier transform, select and shift the spectral components.
In view of the above problems, we proposed an improved method for phase wraps
elimination or reduction. First, the wrapped phase map is padded with zeros,
the carrier frequency of the projected fringe is determined by high resolution,
which can be used as the moving distance of the spectrum. And then realize
frequency shift in spatial domain. So it not only can enable the spectrum to be
shifted by a rational number when the carrier frequency is not an integer
number, but also reduce the execution time. Finally, the experimental results
demonstrated that the proposed method is feasible.Comment: 16 pages, 15 figures, 1 table. arXiv admin note: text overlap with
arXiv:1604.0723
One shot profilometry using iterative two-step temporal phase-unwrapping
This paper reviews two techniques that have been recently published for 3D
profilometry and proposes one shot profilometry using iterative two-step
temporal phase-unwrapping by combining the composite fringe projection and the
iterative two-step temporal phase unwrapping algorithm. In temporal phase
unwrapping, many images with different frequency fringe pattern are needed to
project which would take much time. In order to solve this problem, Ochoa
proposed a phase unwrapping algorithm based on phase partitions using a
composite fringe, which only needs projecting one composite fringe pattern with
four kinds of frequency information to complete the process of 3D profilometry.
However, we found that the fringe order determined through the construction of
phase partitions tended to be imprecise. Recently, we proposed an iterative
two-step temporal phase unwrapping algorithm, which can achieve high
sensitivity and high precision shape measurement. But it needs multiple frames
of fringe images which would take much time. In order to take into account both
the speed and accuracy of 3D shape measurement, we get a new, and more accurate
unwrapping method based on composite fringe pattern by combining these two
techniques. This method not only retains the speed advantage of Ochoa's
algorithm, but also greatly improves its measurement accuracy. Finally, the
experimental evaluation is conducted to prove the validity of the proposed
method, and the experimental results show that this method is feasible.Comment: 14 pages, 15 figure
Multiagent Bidirectionally-Coordinated Nets: Emergence of Human-level Coordination in Learning to Play StarCraft Combat Games
Many artificial intelligence (AI) applications often require multiple
intelligent agents to work in a collaborative effort. Efficient learning for
intra-agent communication and coordination is an indispensable step towards
general AI. In this paper, we take StarCraft combat game as a case study, where
the task is to coordinate multiple agents as a team to defeat their enemies. To
maintain a scalable yet effective communication protocol, we introduce a
Multiagent Bidirectionally-Coordinated Network (BiCNet ['bIknet]) with a
vectorised extension of actor-critic formulation. We show that BiCNet can
handle different types of combats with arbitrary numbers of AI agents for both
sides. Our analysis demonstrates that without any supervisions such as human
demonstrations or labelled data, BiCNet could learn various types of advanced
coordination strategies that have been commonly used by experienced game
players. In our experiments, we evaluate our approach against multiple
baselines under different scenarios; it shows state-of-the-art performance, and
possesses potential values for large-scale real-world applications.Comment: 10 pages, 10 figures. Previously as title: "Multiagent
Bidirectionally-Coordinated Nets for Learning to Play StarCraft Combat
Games", Mar 201
Financial reporting with XBRL and its impact on the accounting profession
Since 2010, XBRL (eXtensible Business Reporting Language) has been widely adopted throughout the world. In 2013, both the HMRC (Inland Revenue) and Companies House in the UK accepted XBRL in the iXBRL (inline XBRL) format. Investors have had to face various issues related to XBRL-reported financial information, such as accuracy and interpretability, as well as potential risks with respect to this new format of financial reporting. The purpose of this study is to explore the impact of XBRL on the quality of financial reports and the accounting profession. For this study, a quality index evaluation model was built to examine the quality of financial reports. Over a thousand XBRL and non-XBRL formatted financial reports from three typical XBRL-adopting regions were then evaluated. This study finds that some of the contextual and accessibility qualities of financial reports have been greatly improved after using the XBRL format. However, the issue of accuracy has become more visible in current XBRL filings, due to the smaller and less comprehensive quantity of data stored in such filing systems. Using quality index scoring system, the trained professionals participating in this study confirm that XBRL-formatted financial reports demonstrate a greatly improved searching efficiency. Moreover, these reports generally display a quality superior to non-XBRL formatted financial reports under the designed quality index. More importantly, the quality of XBRL-formatted financial reports uploaded in the same database has been improving year by year. XBRL has not directly affected the accounting profession, being that most companies have outsourced the preparation of XBRL reports. However, it should additionally be noted that the questionnaires and interviews conducted with accountants in XBRL-adopting companies also reveal that these professionals feel increasing pressure both to prepare and to utilise XBRL-formatted financial information internally
From climate risk to the returns and volatility of energy assets and green bonds:A predictability analysis under various conditions
The importance of climate risk as a source of systemic risk for financial markets and the decisions of investors, portfolio managers, and regulators is growing. We examine the directional predictability from two climate risk measures, transition risk and physical risk, to the returns and volatility of European brown and green energy stocks, European carbon emission allowances, and global green bonds. Using daily data, we apply a cross-quantilogram approach in a time-varying setting to measure potential differences in the predictability across quantiles and over various crisis periods. The return predictability results are more pronounced for transition risk than physical risk, especially for brown energy stocks and carbon emission allowances, and they generally vary across periods and markets conditions. The predictability of volatility is also significant at specific time periods and volatility states, especially from transition risk, and the sign of the predictability is positive for brown energy and carbon emission allowances whereas it is negative for green bonds. We show that a lower-than-expected level of discussion about the transition process leads to a heightened volatility of brown energy markets. These findings have important implications regarding climate risks assessment on return and volatility predictability and climate risk and portfolio decarbonization under COP26. © 2023 Elsevier Inc
Anomalous wavefront control via nonlinear acoustic metasurface through second-harmonic tailoring and demultiplexing
We propose a nonlinear acoustic metasurface concept by exploiting the
nonlinearity of the locally resonant unit cells formed by curved beams. The
analytical model is established to explore the nonlinear phenomenon,
specifically the second-harmonic generation (SHG) of the acoustic waveguide and
validated through numerical and experimental studies. Novel nonlinear acoustic
metasurfaces are developed to demultiplex different frequency components and
achieve anomalous wavefront control of SHG in the transmitted region. To this
end, we demonstrate wave steering, wave focusing, and self-bending propagation.
Our results show that the proposed nonlinear metasurface provides an effective
and efficient platform to achieve significant SHG, and separate different
harmonic components for wavefront control of individual harmonics. Overall,
this study offers new avenues to harness nonlinear effects for acoustic
wavefront tailoring and develops new potential toward advanced technologies to
manipulate acoustic waves
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