ZerNet: Convolutional Neural Networks on Arbitrary Surfaces Via Zernike Local Tangent Space Estimation

In this paper, we propose a novel formulation extending convolutional neural networks (CNN) to arbitrary two-dimensional manifolds using orthogonal basis functions called Zernike polynomials. In many areas, geometric features play a key role in understanding scientific trends and phenomena, where accurate numerical quantification of geometric features is critical. Recently, CNNs have demonstrated a substantial improvement in extracting and codifying geometric features. However, the progress is mostly centred around computer vision and its applications where an inherent grid-like data representation is naturally present. In contrast, many geometry processing problems deal with curved surfaces and the application of CNNs is not trivial due to the lack of canonical grid-like representation, the absence of globally consistent orientation and the incompatible local discretizations. In this paper, we show that the Zernike polynomials allow rigourous yet practical mathematical generalization of CNNs to arbitrary surfaces. We prove that the convolution of two functions can be represented as a simple dot product between Zernike coefficients and the rotation of a convolution kernel is essentially a set of 2 × 2 rotation matrices applied to the coefficients. The key contribution of this work is in such a computationally efficient but rigorous generalization of the major CNN building blocks.     

Effect of boron addition on the microstructure and mechanical properties of 6.5% V-5% W high speed steel

The effect of adding 0.04% additional boron to 6.5% V-5% W high speed steel was investigated. The microstructure characterization, phase identification, and carbide identification of the materials were performed using SEM/EDS and XRD. The cell size and carbide volume fraction were examined using image analysis software. The boron distribution was observed by PTA Boron Tracking. The addition of 0.04% more boron to a HSS alloy exerted a cell refining effect on the sample. The cell refinement of dendritic structures in the alloy containing boron may be attributed to the constitutional supercooling effect associated with the fairly small distribution coefficient for boron in iron. The addition of boron increases the bending strength of the material by more than 10%, as well as increasing its hardness.     

An adaptive ARQ–HARQ interworking scheme in WiMAX systems

For reliable data transmissions, WiMAX systems support automatic repeat query (ARQ) that operates at the upper MAC and hybrid automatic repeat query (HARQ) that operates at the lower MAC and PHY. ARQ and HARQ schemes have their own weakness that results in low throughput and high delay in WiMAX systems. Although ARQ and HARQ schemes can complement with each other, they operate independently. Some studies focus on the benefits of the interaction between ARQ and HARQ schemes, but these studies have limitations. In this paper, we propose an adaptive ARQ and HARQ interworking scheme to provide reliable transmissions without performance degradation in WiMAX systems. The proposed scheme has five features that are designed to solve the weaknesses of the ARQ and HARQ schemes. We compare the proposed scheme with existing schemes that utilize the ARQ and HARQ interaction through simulations, and the simulation results show that the proposed scheme shows improved performance over existing schemes.     

Importance of initial aortic properties on the evolving regional anisotropy, stiffness and wall thickness of human abdominal aortic aneurysms

Complementary advances in medical imaging, vascular biology and biomechanics promise to enable computational modelling of abdominal aortic aneurysms to play increasingly important roles in clinical decision processes. Using a finite-element-based growth and remodelling model of evolving aneurysm geometry and material properties, we show that regional variations in material anisotropy, stiffness and wall thickness should be expected to arise naturally and thus should be included in analyses of aneurysmal enlargement or wall stress. In addition, by initiating the model from best-fit material parameters estimated for non-aneurysmal aortas from different subjects, we show that the initial state of the aorta may influence strongly the subsequent rate of enlargement, wall thickness, mechanical behaviour and thus stress in the lesion. We submit, therefore, that clinically reliable modelling of the enlargement and overall rupture-potential of aneurysms may require both a better understanding of the mechanobiological processes that govern the evolution of these lesions and new methods of determining the patient-specific state of the pre-aneurysmal aorta (or correlation to currently unaffected portions thereof) through knowledge of demographics, comorbidities, lifestyle, genetics and future non-invasive or minimally invasive tests.     

Policy measures to overcome barriers to energy renovation of existing buildings

Even though there is great potential to reduce greenhouse gas emissions from existing buildings, most political effort in Korea has been focused on the construction of new buildings; few concrete measures have been taken to limit greenhouse gas emissions from existing buildings. This study examined the potential to reduce greenhouse gas emissions from existing residential buildings as a means to cope with global warming. Additionally, several barriers to improving the energy performance of existing dwellings instead of constructing new dwellings were explored. The major barriers to improving the energy performance of existing residential buildings are: (1) a lack of awareness; (2) financial reasons; (3) insufficient information; and (4) the absence of regulatory systems. To overcome such barriers, systems adopted and implemented in developed European countries were considered and their feasibility was verified so that political measures could be suggested to improve the energy performance of existing dwellings in Korea.     

Numerical analysis of flow distribution for combined weapon system in environmental tester

Thermal behaviors of combined weapon systems were analyzed by developed computational programs in this study. Also, temperature distributions of the materials of the system were measured according to the experimental conditions. Field tests that reflected the calculated thermal flow characteristics and the measured temperature distributions of the materials were prepared in a large environmental tester for the weapon systems. Boundary conditions of the analysis were the inlet and outlet conditions of the environmental tester and the low temperature limit of ?32°C. The soaking time of the system, including a fuel tank and a battery in the environmental tester, was obtained by the programs developed in this study to carry out the experiment in the predicted conditions.     

The effect of damper leakage and fire size on the performance of smoke control system in high-rise building

Journal of Mechanical Science and Technology - The major function of smoke control system is to prevent smoke from penetrating to vertical shaft or stairwell by pressurizing vestibule where is...     

A Surface Tailoring Method of Ultrathin Polymer Gate Dielectrics for Organic Transistors: Improved Device Performance and the Thermal Stability Thereof

Tailoring the surface of the dielectric layer is of critical importance to form a good interface with the following channel layer for organic thin film transistors (OTFTs). Here, a simple surface treatment method is applied onto an ultrathin (<15 nm) organosilicon‐based dielectric layer via the initiated chemical vapor deposition (iCVD) to make it compatible with organic semiconductors without degrading its insulating property. A molecular‐thin oxide capping layer is formed on a 15 nm thick poly(1,3,5‐trimetyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) by a brief oxygen plasma treatment. The capping layer greatly enhances the thermal stability of the dielectrics, without degrading the original mechanical flexibility and insulating performance of the dielectrics. Moreover, the surface silanol functionalities formed by the plasma treatment can also be utilized for the surface modification with silane compounds. The surface‐modified dielectrics are applied to fabricate low‐voltage operating (<5 V) pentacene‐based OTFTs. The highest field‐effect mobility of the device with the surface‐treated 15 nm thick pV3D3 is 0.59 cm² V^?1 s^?1, which is improved up to two times compared to the TFT with the pristine pV3D3. It is believed that the simple surface treatment method can widely extend the applicability of the highly robust, ultrathin, and flexible pV3D3 gate dielectrics to design the surface of the dielectrics to match well various kinds of organic semiconductors.     

Formation and Accumulation of Intragranular Pores in the Hydrothermally Synthesized Barium Titanate Nanoparticles

As highly integrated circuits are demanded for high‐performance electric devices, small sizes of barium titanate (BaTiO₃) as a dielectric material are desirable for the application of multilayer ceramic capacitors. Since the small sizes of the particles degrade the dielectric property, especially below a certain critical size, understanding the probable cause is significant for the high‐performance capacitors. Here, we have demonstrated nanosized BaTiO₃ with average size below 30 nm and a uniform size distribution. High‐resolution transmission electron microscopy (TEM) shows that the as‐synthesized BaTiO₃ contains intragranular pores. We have analyzed the correlation between the intragranular pores inside nanoparticles and their phase ratio of cubic and tetragonal. We have found that the presence of the intragranular pores affects low tetragonality of BaTiO₃ particles, and the intragranular pores are generated by the accumulation of hydroxyl groups during hydrothermal reaction. Formation and accumulation of intragranular pores have been investigated by ex‐situ synchrotron X‐ray diffraction and TEM analysis, suggesting the phase evolution model of nanosized BaTiO₃.