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Real-time Monte Carlo denoising aims to denoise a 1spp-rendered image with a limited time budget. Many latest techniques for real-time Monte Carlo denoising utilize temporal accumulation (TA) as a pre-processing to improve the temporal stability of successive frames and increase the effective spp. However, existing techniques using TA used to suffer from significant performance degradation when TA does not work well. In addition, they have the disadvantage of deteriorating performance in dynamic scenes because pixel information of the current frame cannot be sufficiently utilized due to the pixel averaging effect between temporally adjacent frames. To solve this problem, this paper proposes a framework that utilizes both 1spp images and temporally accumulated 1spp (TA-1spp) images. First, the multi-scale kernel prediction module estimates kernel maps for filtering 1spp images and TA-1spp images, respectively. Then, the filtered images are properly fused so that the two advantages of 1spp and TA-1spp images can create synergy. Also, the remaining noise is removed through the refinement module and fine details are reconstructed to improve the model flexibility, beyond using only the kernel prediction module. As a result, we achieve better quantitative and qualitative performance at 39% faster than state-of-the-art (SOTA) real-time Monte Carlo denoisers.

This paper presents a framework for effectively applying knowledge distillation (KD) to super-resolution (SR) tasks for computer graphics (CG) images. Specifically, we propose TAKDSR, a KD framework for SR using a teacher assistant (TA) network. Recently, the performance of SR models has improved dramatically thanks to the development of deep learning. SR models have evolved into a form that requires a considerable amount of computation and parameters while adopting a complex neural network structure to improve performance. However, it is difficult to utilize conventional high-performance SR models for real-time up-scaling in CG applications requiring high resolution and high frame rate. To solve this, we employ an approach that applies KD to a lightweight SR model. At this time, if the high-resolution (HR) image is used as input for the teacher to show superior performance to the student, a large performance difference occurs between the two due to the excessive performance of the teacher. As a result, the teacher’s knowledge has a significantly hard and complex nature, and when transferred to the student, the effect of KD can be rather weakened. Therefore, we adopt a TA network to facilitate the propagation of knowledge between teacher and student. At the same time, the distribution of compact features (CF), which are the decoder input of the teacher, is discretized so that it is compatible with the input distribution of the student, enabling effective KD. Experimental results demonstrate the proposed TAKDSR significantly improves the performance of a given SR model on CG image datasets.

The present study explores turbulence statistics in turbulent flow over urban-like terrain using direct numerical simulation (DNS). DNS is performed in a turbulent boundary layer (TBL) over 3D cubic roughness elements. The turbulence statistics at Reτ = 816 are compared with those of experimental and numerical studies for validation, where Reτ is the friction Reynolds number. The flow exhibits wake interference characteristics similar to k-type roughness. Logarithmic variations in streamwise and spanwise Reynolds stresses and a plateau in Reynolds shear stress are observed, reminiscent of Townsend’s attached-eddy hypothesis. The energy at long wavelengths near the top of elements extends to smaller scales, indicating a two-scale behavior and a potential link to amplitude modulation. The quadrant analysis of Reynolds shear stress is employed, revealing significant changes in the contributions of ejection and sweep events near the top of elements. The results of quadrant analysis in the outer region closely resemble those of a TBL over a smooth wall, aligning with Townsend’s outer-layer similarity. The analysis of the transport equation of turbulent kinetic energy highlights the role of the roughness elements in energy transfer, especially pressure transport. Streamwise energy is mainly reduced near upstream elements and redirected in other directions.

Abstract In this paper, we consider the general decay of solutions for the weak viscoelastic equation of Kirchhoff type containing Balakrishnan–Taylor damping with nonlinear delay and acoustic boundary conditions. By using suitable energy and Lyapunov functionals, we prove the general decay for the energy, which depends on the behavior of both σ and k.

Background Locomotor activity in mice may have an ultradian rest-activity rhythm. However, to date, no study has shown how locomotor activity can be explained statistically using fitted cosine curves. Therefore, this study explored whether the ultradian rhythm of locomotor activity in mice could be analyzed using cosine fitting analysis. Methods The locomotor activity of 20 male mice under a 12/12-hour dark/light cycle for 2 days was fitted to a cosine function to obtain the best fit. The mean absolute error (MAE) values were used to determine the explanatory power of the calculated cosine model for locomotor activity. The cosine fitting analysis was performed using R statistical software (version 4.1.1). Results The mean MAE was 0.2944, whereas the mean MAE for integrating the individual analyses in the two experimental groups was 0.3284. The periods of the estimated ultradian rest-activity rhythm ranged from 1.602 to 4.168 hours. Conclusions These results suggest that locomotor activity data reflect an ultradian rhythm better than a circadian rhythm. Locomotor activity can be statistically fitted to a cosine curve under well-controlled conditions. In the future, it will be necessary to explore whether this cosine-fitting analysis can be used to analyze ultradian rhythms under different experimental conditions.

As an extension of the previous work, this paper is concerned with the modeling of composite sandwich shells in a dynamic framework. The variational-asymptotic method is first used to construct an equivalent shell model taking into account inertial and transverse deformation effects, but still providing the zeroth-order approximation. At this time, each layer of the sandwich structure is individually considered as a shell in which all material constitutive constants have the same order. Next, the sandwich shell is regarded as the assembly of three curved layers with mismatched material and geometric properties, whereby an order transition in the transverse deformations occurs. By imposing continuity conditions on the interfaces between layers, a universal model with a three-dimensional recovery relation is systematically derived, allowing the mechanical behaviors of composite sandwich shells to be predicted. Finally, preliminary validations are implemented to demonstrate the capabilities and accuracy of the present approach.

Data aggregation techniques have been widely used in wireless sensor networks (WSNs) to solve the energy constraint problems of sensor nodes. They can conserve the significant amount of energy by reducing data packet transmission costs. However, many data aggregation applications require privacy and integrity protection of the real data while transmitting data from the sensing nodes to a sink node. The existing schemes for supporting both privacy and integrity, that is, iCDPA, and iPDA, suffer from high communication cost, high computation cost, and data propagation delay. To resolve the problems, we propose a signature-based data security technique for protecting sensitive data aggregation in WSNs. To support privacy-preserving data aggregation and integrity checking, our technique makes use of the additive property of complex numbers. Out of two parts of a complex number, the real part is used to hide the sampled data of a sensor node from its neighboring nodes and adversaries, whereas the imaginary part is used for data integrity checking at both data aggregators and the sink node. Through a performance analysis, we prove that our privacy-preserving data aggregation scheme outperforms the existing schemes up to 50% in terms of communication and computation overheads as well as up to 3 times in terms of integrity checking and data propagation delay.

Data aggregation techniques have been proposed for wireless sensor networks (WSNs) to address the problems presented by the limited resources of sensor nodes. The provision of efficient data aggregation to preserve data privacy is a challenging issue in WSNs. Some existing data aggregation methods for preserving data privacy are CPDA, SMART, the Twin-Key based method, and GP2S. These methods, however, have two limitations. First, the communication cost for network construction is considerably high. Second, they do not support data integrity. There are two methods for supporting data integrity, iCPDA and iPDA. But they have high communication cost due to additional integrity checking messages. To resolve this problem, we propose a novel Hilbert-curve based data aggregation scheme that enforces data privacy and data integrity for WSNs. To minimize communication cost, we utilize a tree-based network structure for constructing networks and aggregating data. To preserve data privacy, we make use of both a seed exchange algorithm and Hilbert-curve based data encryption. To support data integrity, we use an integrity checking algorithm based on the PIR technique by directly communicating between parent and child nodes. Finally, through a performance analysis, we show that our scheme outperforms the existing methods in terms of both energy efficiency and privacy preservation.

Background: Sigmoid sinus diverticulum/dehiscence (SSD) is one of the treatable causes of venous pulsatile tinnitus. It can be diagnosed using temporal bone computed tomography (CT) or magnetic resonance angiography/venography (MRA). In cases where patients find their symptoms intolerable, surgical treatment is typically preferred. Here, we have presented a novel surgical technique involving sigmoid sinus re-roofing and have analyzed its feasibility. Methods: Between January 2020 and July 2023, approximately 150 patients with pulsatile tinnitus were evaluated at two different tertiary hospitals. Of these, 12 patients were diagnosed with SSD, and seven underwent surgical treatment. Five patients were treated with tailored reroofing (TRR) of the sigmoid sinus and two with transmastoid resurfacing (MRS) of the sigmoid sinus. We compared the Korean tinnitus handicap inventory (K-THI) score, pure tone audiogram (PTA) threshold, and CT findings before and a month after surgeries for these two techniques. The operation time was also analyzed. Results: In TRR cases, the K-THI score reduced from 55.0 ± 31.4 preoperatively to 4.0 ± 3.0 postoperatively, and the SSD was well-repositioned and covered by a bone chip postoperatively. In MRS cases, the K-THI score reduced from 41.0 ± 9.9 preoperatively to 15.0 ± 21.2 postoperatively, and the SSD was well-covered with bone cement postoperatively. The average surgical time of five TRR and two MRS cases were 77.5 ± 32.5 and 174.0 ± 75.0 min, respectively. No complications were noted. Conclusions: Despite the insufficient number of cases, we noted that TRR requires a reasonable amount of time, involves a smaller incision, and may provide favorable outcomes compared to conventional MRS in cases of pulsatile tinnitus associated with SSD. [ABSTRACT FROM AUTHOR]

Functionally graded materials are innovative composites of hybrid ceramics and metals that exhibit excellent mechanical performance in harsh temperature environments and under various external loads. In this study, the free vibrations of Timoshenko circular arches, made of functionally graded materials in the axial direction, are investigated. The material properties of Young's modulus and mass density of the arch vary according to a symmetric quadratic function along the arch axis. Differential equations governing the free vibration of the arch including the rotatory inertia and shear deformation, called the Timoshenko arch, are derived. A novel numerical solution method is developed to calculate the natural frequencies and mode shapes of the arch. Parametric studies of the modular ratio, shear correction factor, shear modulus ratio, and slenderness ratio on the natural frequencies are conducted, and the results are reported in the tables and figures. [ABSTRACT FROM AUTHOR]

Background/Aims: Local ablation therapy (LAT) is primarily recommended for solitary inoperable hepatocellular carcinomas (HCCs) of ≤3 cm in diameter. However, only two-thirds of uninodular small HCCs are suitable for LAT, and the second-best treatment option for managing these nodules is unclear. We aimed to compare the therapeutic outcomes of chemoembolization and radiotherapy in small HCCs unsuitable for LAT. Methods: The study included 651 patients from a tertiary referral center who underwent planning sonography for LAT. These patients had 801 solitary HCCs of ≤3 cm in diameter and were treated with LAT, chemoembolization, or radiotherapy. Local tumor progression (LTP)-free survival and overall survival (OS) were measured according to the type of treatment of the index nodule. Results: LAT, chemoembolization, and radiotherapy were used to treat 561, 185, and 55 nodules in 467, 148, and 36 patients, respectively. LTP-free survival was significantly shorter in patients treated with chemoembolization than for those treated with LAT (multivariate hazard ratio [HR], 2.36; 95% confidence interval [CI], 1.61 to 3.47) but not for those treated with radiotherapy (HR, 0.83; 95% CI, 0.38 to 1.83). However, OS was not affected by treatment modality. Matching and weighting analyses confirmed that radiotherapy gave comparable results to chemoembolization in terms of OS despite better LTP-free survival (HR, 2.91; 95% CI, 1.13 to 7.47 and HR, 3.07; 95% CI, 1.11 to 8.48, respectively). Conclusions: Our data suggest that chemoembolization and radiotherapy are equally effective options for single small HCCs found to be unsuitable for LAT after sonographic planning. Betterfit indications for each procedure should be established by specifically designed studies [ABSTRACT FROM AUTHOR]

This study was conducted to determine the correlation between the mass loss (ML) of wood due to thermal modification and the equilibrium moisture content (EMC) of thermally modified wood. After thermal modification of larch lumber under various temperature and time conditions, ML according to treatment temperature and time was measured, and the (EMC) of the thermally modified wood was evaluated for each treatment condition. As the treatment temperature increased and the treatment time became longer, the ML of wood due to thermal modification increased. In addition, as the treatment temperature increased, the difference in EMC between the non-treated wood and the thermally modified wood tended to increase. Finally, a robust logarithmic correlation was observed between the ML due to thermal modification and the EMC of the thermally modified wood. These results suggest that the EMC of thermally modified wood can be predicted by simply measuring the weight of wood before and after thermal modification. [ABSTRACT FROM AUTHOR]