Unmanned Aerial Vehicle (UAV) inspection of transmission channels in mountainous areas is susceptible to non-homogeneous fog, such as up-slope fog and advection fog, which causes crucial portions of ...transmission lines or towers to become fuzzy or even wholly concealed. This paper presents a Dual Attention Level Feature Fusion Multi-Patch Hierarchical Network (DAMPHN) for single image defogging to address the bad quality of cross-level feature fusion in Fast Deep Multi-Patch Hierarchical Networks (FDMPHN). Compared with FDMPHN before improvement, the Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index Measure (SSIM) of DAMPHN are increased by 0.3 dB and 0.011 on average, and the Average Processing Time (APT) of a single picture is shortened by 11%. Additionally, compared with the other three excellent defogging methods, the PSNR and SSIM values DAMPHN are increased by 1.75 dB and 0.022 on average. Then, to mimic non-homogeneous fog, we combine the single picture depth information with 3D Berlin noise to create the UAV-HAZE dataset, which is used in the field of UAV power assessment. The experiment demonstrates that DAMPHN offers excellent defogging results and is competitive in no-reference and full-reference assessment indices.
A striking and unexpected feature of the financial crisis has been the sharp appreciation of the US dollar against virtually all currencies globally. The paper finds that negative US-specific ...macroeconomic shocks during the crisis have triggered a significant strengthening of the US dollar, rather than a weakening. Macroeconomic fundamentals and financial exposure of individual countries are found to have played a key role in the transmission process of US shocks: in particular countries with low FX reserves, weak current account positions and high direct financial exposure vis-à-vis the United States have experienced substantially larger currency depreciations during the crisis overall, and to US shocks in particular.
This brief investigates the problem of secure state estimation (SSE) for cyber-physical systems (CPSs) which communicate through multiple channels under denial of service (DoS) attacks, where the ...considered DoS attacks occur aperiodically and independently in all channels. The only limitation for DoS attacks is that the duration of each attack is bounded. First, a secure transmission strategy is given to transmit signals and resist DoS attacks. Then, a novel fixed-time secure state estimation (FTSSE) method is proposed to ensure that the SSE for CPSs is realized within a predetermined fixed-time based on the developed secure transmission strategy. In addition, the accurate state values of some moments can be obtained at a given delay time. The sufficient condition and the proof of effectiveness for the FTSSE method based on secure transmission strategy are given through theoretical analysis. Finally, the results of an example simulation are given to verify the effectiveness of the designed method.
This paper investigates the resilient control problem for cyber-physical systems (CPSs) with multiple transmission channels under denial-of-service (DoS). First, a set of partial observers is ...designed to estimate partial states corresponding to different channels. Second, by combining the proposed partial observers, the finite-time observer technique and a switching scheme, a modified finite-time partial observer-based controller is proposed to stabilize the system in the presence of DoS. Compared with the existing results for the CPSs with multiple transmission channels, the computational burden of designing observer-based controller is reduced, and the resilience against DoS is improved by adopting the proposed finite-time partial observers. Especially, besides stability, the proposed resilient observer-based controller also provides better disturbance rejection performance.
This article investigates the stability analysis problem for cyber-physical systems (CPSs) under denial-of-service (DoS) attacks. Based on the real-time data characterizing the suffered DoS attack, a ...necessary and sufficient condition for the closed-loop stability in the presence of DoS attacks is provided. Besides, by transforming stability analysis the system under DoS into stability analysis of an auxiliary system, novel sufficient conditions for the closed-loop stability, which can be verified more easily than the necessary and sufficient condition, are provided. Based on the proposed conditions, an online stability monitoring strategy, which triggers an alarm if the closed-loop stability is not guaranteed, is proposed. Finally, two examples are given to illustrate the effectiveness of the proposed strategy.
Although international sanctions are a widely used instrument of coercion, their economic effects are still not well-understood. This study uses a novel dataset and an event study approach to ...evaluate the economic consequences of international sanctions, thereby visualizing pre-treatment and treatment dynamics in countries subject to sanctions. Our analysis focuses on the effects of sanctions on GDP growth as well as on various transmission channels through which sanctions suppress economic activity. We document a significant negative effect of sanctions on the growth rate of GDP and its components (consumption and investment) as well as on trade and foreign direct investment. Given that sanctions exert their adverse effect over the first years of a sanction episode and that sanctioned countries fail to recover during or immediately after the episode, we demonstrate the usefulness of sanctions as a political instrument of coercion. Long-lasting sanctions regimes, however, may not provide the political incentives needed to force additional concessions.
•We evaluate the economic consequences of international sanctions.•Our analysis relies on a novel dataset and an event study approach.•We find a negative effect on economic growth and its components.•Trade and FDI decline, whereas military expenditures in democracies increase.•Adverse economic effects are strongest in the first two years of a sanction episode.
•. Dynamic time-frequency risk connectedness is explored from a quantile perspective.•Climate transition risks, oil demand and risk shocks mediate the channels of risk transmission.•Global warming, ...oil supply shock and climate summit events are the greatest shocks.•The impact of climate risks and oil shocks on energy futures is asymmetric under extremes.•Climate risks and oil shocks show more pronounced impact in the short term.
This study investigates the dynamic risk nexus among climate risks, oil shocks and China’s energy futures market from a time–frequency-quantile perspective. We first explore the dynamic connectedness of “climate risks – oil shocks – energy futures” and examine the risk transmission channels through mediation effects model. The Quantile-on-Quantile regression is used to study the time–frequency impact of climate risks and oil shocks on energy futures across different market conditions and investment horizons. Our empirical results are as follows: First, climate transition risks, oil demand and risk shocks play mediating roles in risk transmission channels. Second, the impact of climate risks and oil shocks on energy futures is heterogeneous and asymmetric under extreme conditions. Notably, global warming, oil supply shock and international climate summits are the greatest shocks to China’s energy market. Finally, climate risks and oil shocks are more pronounced in the short term. Overall, these findings offer valuable insights for shaping risk management strategies and implementing effective hedging practices within the energy market.
The banking literature does not provide consensus over the impact of Fintech on banks. On the one hand, Fintech advancements are poised to enhance the accessibility of financial services; on the ...other, it can lead to alterations in market structure. Thus, it is important to ascertain the impact of Fintech entry from both perspectives. We examine the impact of Fintech entry on financial inclusion (FI) and banking competition by introducing conditionalities and non-linearity to uncover the potential transmission channels for Fintech to affect inclusion and market structure. Findings suggest episodes of low and medium inclusion from 2005 till 2018. However, post 2018, there has been a significant increase in FI. Similarly, persistent monopolistic tendencies were observed with most banks enjoying higher Lerner margins. The extent of Fintech reveals highly sluggish growth over 2005 to 2015. However, post 2016, drastic increase is observed commensurate with the central bank's regulatory push. Further, Fintech is inversely related to banks' market power indicating a diminishing effect. We propose three transmission mechanisms for Fintech effects: the inclusion channel, the growth channel, and the regulatory environment. In addition, we find a significant and positive impact of Fintech on FI however, the relationship is essentially non-linear.
•We investigate the explicit impacts of financial frictions on corporate investment activity through the external financing channel.•During the period of financial distress, financial frictions tend ...to affect the investment activity of financially constrained companies.•Policy measures should be designed to ensure the availability of external financing, targeted at financially constrained companies.
In this paper, we investigate the impact of imperfect financial markets on the business investment of Slovenian non-financial companies. We focus on exploring the borrower's balance sheet channel, through which companies’ worsening balance sheets, reduce the availability of external finance. The effects of exogenous shocks are, therefore, amplified through the financial accelerator mechanism and affect the overall economy. Using data from annual reports of Slovenian non-financial companies from 2005 to 2020, we estimate a panel VAR model on various sample definitions. The results confirm the existence of the balance sheet channel, as the impulse response of investment to cash flow shocks is statistically significant. This effect is especially noticeable during the period from 2006 to 2012. Our findings suggest that financial frictions affect the availability of external financing and, consequently, the investment activity of Slovenian non-financial companies. Policymakers should prioritize measures to ensure adequate external financing, particularly for financially constrained firms, to mitigate the negative impact of reduced economic activity during periods of financial distress and economic downturns.
This paper studies the problem of dynamic event-triggered control in multi-channel cyber–physical systems subject to denial-of-service attacks, and the attacks are independent and asynchronous in ...different channels. A switching scheme is proposed to address the complexity of multi-channel network attacks, under which the sufficient conditions for closed-loop stability of the systems are obtained. Additionally, considering the different decay rates caused by the switching logic, an equivalent decay rates method, which reveals the relationship between the tolerable attack intensity and the dynamic event-triggering parameters, is proposed. Furthermore, it is demonstrated that the dynamic event-triggered strategy outperforms the traditional static approaches in terms of saving communication resources, which is also verified by a simulation example.
PDF
