Wenqing Zhang, Guojun Zhang, Zican Chang, Yabo Zhang, YuDing Wu, YuHui Zhang, JiangJiang Wang, YuHao Huang, RuiMing Zhang and Wendong Zhang
This paper aims to address the challenges in hydroacoustic signal detection, signal distortion and target localization caused by baseline drift. The authors propose a combined…
Abstract
Purpose
This paper aims to address the challenges in hydroacoustic signal detection, signal distortion and target localization caused by baseline drift. The authors propose a combined algorithm that integrates short-time Fourier transform (STFT) detection, smoothness priors approach (SPA), attitude calibration and direction of arrival (DOA) estimation for micro-electro-mechanical system vector hydrophones.
Design/methodology/approach
Initially, STFT method screens target signals with baseline drift in low signal-to-noise ratio environments, facilitating easier subsequent processing. Next, SPA is applied to the screened target signal, effectively removing the baseline drift, and combined with filtering to improve the signal-to-noise ratio. Then, vector channel amplitudes are corrected using attitude correction with 2D compass data. Finally, the absolute target azimuth is estimated using the minimum variance distortion-free response beamformer.
Findings
Simulation and experimental results demonstrate that the SPA outperforms high-pass filtering in removing baseline drift and is comparable to the effectiveness of variational mode decomposition, with significantly shorter processing times, making it more suitable for real-time applications. The detection performance of the STFT method is superior to instantaneous correlation detection and sample entropy methods. The final DOA estimation achieves an accuracy within 2°, enabling precise target azimuth estimation.
Originality/value
To the best of the authors’ knowledge, this study is the first to apply SPA to baseline drift removal in hydroacoustic signals, significantly enhancing the efficiency and accuracy of signal processing. It demonstrates the method’s outstanding performance in the field of underwater signal processing. In addition, it confirms the reliability and feasibility of STFT for signal detection in the presence of baseline drift.
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Keywords
Noel Scott, Brent Moyle, Ana Cláudia Campos, Liubov Skavronskaya and Biqiang Liu
Michael Kopel and Christian Riegler
This paper considers a strategic delegation setting with R&D spillovers in a Cournot market. The game we analyze has four stages. First, owners have the option to hire a manager…
Abstract
This paper considers a strategic delegation setting with R&D spillovers in a Cournot market. The game we analyze has four stages. First, owners have the option to hire a manager. If they decide to delegate, then in the contracting stage they have to determine the optimal incentives for the managers. In the R&D stage, the levels of investments in research and development are chosen which reduce production costs. Finally, in the production stage quantities offered on the market are selected. We characterize the sub-game perfect outcomes of this game depending on the level of R&D spillovers and derive the following main insights. First, in a case where no spillovers exist, both owners have the incentive to delegate R&D and production decisions to managers. This leads to higher outputs, higher R&D activities, but lower profits for the firms in comparison with an entrepreneurial (owner-managed) firm. These results still hold if the basic production unit costs are high, independent of the existence of spillovers. In these cases delegation leads to an increase in social welfare. Second, we demonstrate that when spillovers exist and basic unit production costs are low, then there are situations where owners delegate but discourage managers from being aggressive. This “soft” commitment leads to lower outputs, lower R&D, but higher profits for the firms in comparison with an entrepreneurial firm. Here, however, delegation results in lower welfare.
De-gan Zhang, Xiao-dong Song, Xiang Wang, Ke Li, Wen-bin Li and Zhen Ma
Mobile Service of Big Data can be supported by the fused technologies of computing, communication and digital multimedia. The purpose of this paper is to propose new agent-based…
Abstract
Purpose
Mobile Service of Big Data can be supported by the fused technologies of computing, communication and digital multimedia. The purpose of this paper is to propose new agent-based proactive migration method and system for Big Data Environment (BDE).
Design/methodology/approach
First, the authors have designed new relative fusion method for making decision based on fuzzy-neural network. The method can make the fusion belief degree to be improved. Then the authors have proposed agent-based proactive migrating method with service discovery and key frames selection strategy. Finally, the authors have designed the application system, which can support proactive seamless migration function for big data. The method has innovation in which mobile service task of big data can dynamically follow its mobile user from one device to another device.
Findings
The authors have proposed agent-based proactive migrating method with service discovery and key frames selection strategy. The method has innovation in which mobile service task of big data can dynamically follow its mobile user from one device to another device. The designed system is convenient to work and use during mobility, and which is useful or helpful for mobile user in the BDE.
Originality/value
The authors have clarified and realizes how to transfer service tasks among different distances in Big Data Environment (BDE). The authors have given a formal description and classification of the mobile service task, which is independent of the realization mechanism. In the designed and developed application system, the new idea adopts fuzzy-neural control theory to make decision for task-oriented proactive seamless migration application.
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Yanan He, Xindong Zhang, Panpan Hao, Xiaoyong Dai and Haiyan Xue
This paper investigates whether China's R&D tax deduction policy triggers firms to manipulate their R&D expenditures upward.
Abstract
Purpose
This paper investigates whether China's R&D tax deduction policy triggers firms to manipulate their R&D expenditures upward.
Design/methodology/approach
This paper employs the ratio of actual tax savings as a proxy for the benefits of the R&D tax deduction policy based on manually collected and systematically cross-checked data. The relationship between tax benefits and abnormal R&D spending is estimated in a sample of Chinese A-share listed companies for the period 2007–2018.
Findings
The findings suggest that tax deductions lead to positive abnormal R&D spending and that this deviation in R&D spending may be attributed to firms' upward R&D manipulation for tax avoidance. The results also indicate that this behavior is more significant for the period after the policy revision, in non-HNTEs (high and new technology enterprises), and in firms with a high ratio of R&D expenses.
Research limitations/implications
It is difficult to establish a sophisticated and unified model to identify the specific strategy of upward R&D manipulation that firms use to obtain tax benefits.
Practical implications
Managers should take into account upward R&D manipulation when designing governance mechanisms. Policymakers in developing countries may further pursue preferential tax policies that cover every stage of innovation activities gradually; the local provincial governments need to leverage their proximity and flexibility advantages to develop a tax collection and administration system.
Originality/value
This study contributes to the understanding of the complex effect of R&D tax incentives and helps more fully illuminate firms' upward R&D manipulation behavior from the perspective of tax planning strategies, which are underexplored in previous research.
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Rui Zhang, Lei Zhao, Dan Xie, Jinlong Song, Wendong Zhang, Lihu Pan and Yanhua Zhang
This study aims to simulate and test the performance of a transmitting and receiving capacitive micro-machined ultrasonic transducer (CMUT). Aimed at detecting demand of the CMUT…
Abstract
Purpose
This study aims to simulate and test the performance of a transmitting and receiving capacitive micro-machined ultrasonic transducer (CMUT). Aimed at detecting demand of the CMUT, a matched integrated adjustment circuit was designed through analyzing processing methods of transducer’s weak echo signal.
Design/methodology/approach
Based on the analysis of CMUT array structure and work principle, the CMUT units are designed and the dynamic performance analysis of SIMULINK is given according to the demand of underwater detecting. A transceiver isolation circuit is used to make transmission mode and receiving mode separate. A detection circuit is designed based on the transimpedance amplifier to achieve extraction of high-frequency and weak signal.
Findings
Through experimentation, the effectiveness of the CMUT performance simulation and the transceiver integrated adjustment circuit were verified. In addition, the test showed that CMUT with 400 kHz frequency has wider bandwidth and better dynamic characteristics than other similar transducers.
Originality/value
This paper provides a theoretical basis and design reference for the development and application of CMUT technology.
Details
Keywords
- MEMS
- Dynamic performance
- Ultrasonic sensors
- Underwater applications
- Detection circuit
- Transmission transducer
- Capacitive micro-machined ultrasonic transducer
- Receipt and transmission transducer
- MEMS
- Dynamic performance
- Ultrasonic sensors
- Underwater applications
- Detection circuit
- Transmission transducer
- Capacitive micro-machined ultrasonic transducer