188 research outputs found
Unilateral CVA for CDS in Contagion model: With volatilities and correlation of spread and interest
The price of financial derivative with unilateral counterparty credit risk can be expressed as the price of an otherwise risk-free derivative minus a credit value adjustment(CVA) component that can be seen as shorting a call option, which is exercised upon default of counterparty, on MtM of the derivative. Therefore, modeling volatility of MtM and default time of counterparty is key to quantification of counterparty risk. This paper models default times of counterparty and reference with a particular contagion model with stochastic intensities that is proposed by Bao et al. 2010. Stochastic interest rate is incorporated as well to account for positive correlation between spread and interest. Survival measure approach is adopted to calculate MtM of risk-free CDS and conditional survival probability of counterparty in defaultable environment. Semi-analytical solution for CVA is attained. Affine specification of intensities and interest rate concludes analytical expression for pre-default value of MtM. Numerical experiments at the last of this paper analyze the impact of contagion, volatility and correlation on CVA.Credit Value Adjustment, Contagion Model, Stochastic Intensities and Interest, Survival Measure, Affine Specification
UWFormer: Underwater Image Enhancement via a Semi-Supervised Multi-Scale Transformer
Underwater images often exhibit poor quality, imbalanced coloration, and low
contrast due to the complex and intricate interaction of light, water, and
objects. Despite the significant contributions of previous underwater
enhancement techniques, there exist several problems that demand further
improvement: (i) Current deep learning methodologies depend on Convolutional
Neural Networks (CNNs) that lack multi-scale enhancement and also have limited
global perception fields. (ii) The scarcity of paired real-world underwater
datasets poses a considerable challenge, and the utilization of synthetic image
pairs risks overfitting. To address the aforementioned issues, this paper
presents a Multi-scale Transformer-based Network called UWFormer for enhancing
images at multiple frequencies via semi-supervised learning, in which we
propose a Nonlinear Frequency-aware Attention mechanism and a Multi-Scale
Fusion Feed-forward Network for low-frequency enhancement. Additionally, we
introduce a specialized underwater semi-supervised training strategy, proposing
a Subaqueous Perceptual Loss function to generate reliable pseudo labels.
Experiments using full-reference and non-reference underwater benchmarks
demonstrate that our method outperforms state-of-the-art methods in terms of
both quantity and visual quality
ShaDocFormer: A Shadow-attentive Threshold Detector with Cascaded Fusion Refiner for document shadow removal
Document shadow is a common issue that arise when capturing documents using
mobile devices, which significantly impacts the readability. Current methods
encounter various challenges including inaccurate detection of shadow masks and
estimation of illumination. In this paper, we propose ShaDocFormer, a
Transformer-based architecture that integrates traditional methodologies and
deep learning techniques to tackle the problem of document shadow removal. The
ShaDocFormer architecture comprises two components: the Shadow-attentive
Threshold Detector (STD) and the Cascaded Fusion Refiner (CFR). The STD module
employs a traditional thresholding technique and leverages the attention
mechanism of the Transformer to gather global information, thereby enabling
precise detection of shadow masks. The cascaded and aggregative structure of
the CFR module facilitates a coarse-to-fine restoration process for the entire
image. As a result, ShaDocFormer excels in accurately detecting and capturing
variations in both shadow and illumination, thereby enabling effective removal
of shadows. Extensive experiments demonstrate that ShaDocFormer outperforms
current state-of-the-art methods in both qualitative and quantitative
measurements
DocDeshadower: Frequency-aware Transformer for Document Shadow Removal
The presence of shadows significantly impacts the visual quality of scanned
documents. However, the existing traditional techniques and deep learning
methods used for shadow removal have several limitations. These methods either
rely heavily on heuristics, resulting in suboptimal performance, or require
large datasets to learn shadow-related features. In this study, we propose the
DocDeshadower, a multi-frequency Transformer-based model built on Laplacian
Pyramid. DocDeshadower is designed to remove shadows at different frequencies
in a coarse-to-fine manner. To achieve this, we decompose the shadow image into
different frequency bands using Laplacian Pyramid. In addition, we introduce
two novel components to this model: the Attention-Aggregation Network and the
Gated Multi-scale Fusion Transformer. The Attention-Aggregation Network is
designed to remove shadows in the low-frequency part of the image, whereas the
Gated Multi-scale Fusion Transformer refines the entire image at a global scale
with its large perceptive field. Our extensive experiments demonstrate that
DocDeshadower outperforms the current state-of-the-art methods in both
qualitative and quantitative terms
Unilateral CVA for CDS in Contagion Model_with Volatilities and Correlation of Spread and Interest
The price of financial derivative with unilateral counterparty credit risk can be expressed as the price of an otherwise risk-free derivative minus a credit value adjustment(CVA) component that can be seen as shorting a call option, which is exercised upon default of counterparty, on MtM of the derivative. Therefore, modeling volatility of MtM and default time of counterparty is key to quantification of counterparty risk. This paper models default times of counterparty and reference with a particular contagion model with stochastic intensities that is proposed by Bao et al. 2010. Stochastic interest rate is incorporated as well to account for positive correlation between spread and interest. Survival measure approach is adopted to calculate MtM of risk-free CDS and conditional survival probability of counterparty in defaultable environment. Semi-analytical solution for CVA is attained. Affine specification of intensities and interest rate concludes analytical expression for pre-default value of MtM. Numerical experiments at the last of this paper analyze the impact of contagion, volatility and correlation on CVA
Unilateral CVA for CDS in Contagion model: With volatilities and correlation of spread and interest
The price of financial derivative with unilateral counterparty credit risk can be expressed as the price of an otherwise risk-free derivative minus a credit value adjustment(CVA) component that can be seen as shorting a call option, which is exercised upon default of counterparty, on MtM of the derivative. Therefore, modeling volatility of MtM and default time of counterparty is key to quantification of counterparty risk. This paper models default times of counterparty and reference with a particular contagion model with stochastic intensities that is proposed by Bao et al. 2010. Stochastic interest rate is incorporated as well to account for positive correlation between spread and interest. Survival measure approach is adopted to calculate MtM of risk-free CDS and conditional survival probability of counterparty in defaultable environment. Semi-analytical solution for CVA is attained. Affine specification of intensities and interest rate concludes analytical expression for pre-default value of MtM. Numerical experiments at the last of this paper analyze the impact of contagion, volatility and correlation on CVA
Unilateral CVA for CDS in Contagion Model_with Volatilities and Correlation of Spread and Interest
The price of financial derivative with unilateral counterparty credit risk can be expressed as the price of an otherwise risk-free derivative minus a credit value adjustment(CVA) component that can be seen as shorting a call option, which is exercised upon default of counterparty, on MtM of the derivative. Therefore, modeling volatility of MtM and default time of counterparty is key to quantification of counterparty risk. This paper models default times of counterparty and reference with a particular contagion model with stochastic intensities that is proposed by Bao et al. 2010. Stochastic interest rate is incorporated as well to account for positive correlation between spread and interest. Survival measure approach is adopted to calculate MtM of risk-free CDS and conditional survival probability of counterparty in defaultable environment. Semi-analytical solution for CVA is attained. Affine specification of intensities and interest rate concludes analytical expression for pre-default value of MtM. Numerical experiments at the last of this paper analyze the impact of contagion, volatility and correlation on CVA
A numerical landslide-tsunami hazard assessment technique applied on hypothetical scenarios at Es Vedrà, offshore Ibiza
This study presents a numerical landslide-tsunami hazard assessment technique for applications in reservoirs, lakes, fjords, and the sea. This technique is illustrated with hypothetical scenarios at Es Vedrà, offshore Ibiza, although currently no evidence suggests that this island may become unstable. The two selected scenarios include two particularly vulnerable locations, namely: (i) Cala d’Hort on Ibiza (3 km away from Es Vedrà) and (ii) Marina de Formentera (23 km away from Es Vedrà). The violent wave generation process is modelled with the meshless Lagrangian method smoothed particle hydrodynamics. Further offshore, the simulations are continued with the less computational expensive code SWASH (Simulating WAves till SHore), which is based on the non-hydrostatic non-linear shallow water equations that are capable of considering bottom friction and frequency dispersion. The up to 133-m high tsunamis decay relatively fast with distance from Es Vedrà; the wave height 5 m offshore Cala d’Hort is 14.2 m, reaching a maximum run-up height of over 21.5 m, whilst the offshore wave height (2.7 m) and maximum inundation depth at Marina de Formentera (1.2 m) are significantly smaller. This study illustrates that landslide-tsunami hazard assessment can nowadays readily be conducted under consideration of site-specific details such as the bathymetry and topography, and intends to support future investigations of real landslide-tsunami cases
Unilateral CVA for CDS in contagion model: with volatilities and correlation of spread and interest
The price of financial derivative with unilateral counterparty credit risk can be expressed as the price of an otherwise risk-free derivative minus a credit value adjustment(CVA) component that can be seen as shorting a call option, which is exercised upon default of counterparty, on MtM of the derivative. Therefore, modeling volatility of MtM and default time of counterparty is key to quantification of counterparty risk. This paper models default times of counterparty and reference with a particular contagion model with stochastic intensities that is proposed by Bao et al. 2010. Stochastic interest rate is incorporated as well to account for positive correlation between spread and interest. Survival measure approach is adopted to calculate MtM of risk-free CDS and conditional survival probability of counterparty in defaultable environment. Semi-analytical solution for CVA is attained. Affine specification of intensities and interest rate concludes analytical expression for pre-default value of MtM. Numerical experiments at the last of this paper analyze the impact of contagion, volatility and correlation on CVA
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