Neural Diffeomorphic Non-uniform B-spline Flows

Normalizing flows have been successfully modeling a complex probability distribution as an invertible transformation of a simple base distribution. However, there are often applications that require more than invertibility. For instance, the computation of energies and forces in physics requires the second derivatives of the transformation to be well-defined and continuous. Smooth normalizing flows employ infinitely differentiable transformation, but with the price of slow non-analytic inverse transforms. In this work, we propose diffeomorphic non-uniform B-spline flows that are at least twice continuously differentiable while bi-Lipschitz continuous, enabling efficient parametrization while retaining analytic inverse transforms based on a sufficient condition for diffeomorphism. Firstly, we investigate the sufficient condition for Ck-2-diffeomorphic non-uniform kth-order B-spline transformations. Then, we derive an analytic inverse transformation of the non-uniform cubic B-spline transformation for neural diffeomorphic non-uniform B-spline flows. Lastly, we performed experiments on solving the force matching problem in Boltzmann generators, demonstrating that our C2-diffeomorphic non-uniform B-spline flows yielded solutions better than previous spline flows and faster than smooth normalizing flows. Our source code is publicly available at https://github.com/smhongok/Non-uniform-B-spline-Flow.Comment: Accepted to AAAI 202

Two-dimensional heterogeneous photonic bandedge laser

We proposed and realized a two-dimensional (2D) photonic bandedge laser surrounded by the photonic bandgap. The heterogeneous photonic crystal structure consists of two triangular lattices of the same lattice constant with different air hole radii. The photonic crystal laser was realized by room-temperature optical pumping of air-bridge slabs of InGaAsP quantum wells emitting at 1.55 micrometer. The lasing mode was identified from its spectral positions and polarization directions. A low threshold incident pump power of 0.24mW was achieved. The measured characteristics of the photonic crystal lasers closely agree with the results of real space and Fourier space calculations based on the finite-difference time-domain method.Comment: 14 pages, 4 figure

Implementation of Cloth Simulation Using Parallel Computing on Mobile Device

Physically based modeling and simulation is an important technique for deformable object simulation, which is widely used to represent the realistic shape change and movement of objects for mobile game or 3D simulation. However, they require the high computational cost for representing the physical phenomenon on deformable objects when it applied on mobile device. In this paper, we designed and implemented the cloth simulation for deformable object simulation using the parallel technique on mobile device to optimize the computational burden. We especially applied GPU parallel technique for the integration solving process such as Euler, Midpoint, 4th-order Runge-Kutta method to estimate the particles' next status using positions and velocities. Also we applied multi-thread parallel technique for calculating the spring force. Then we compared the performance of each integration methods between under only CPU and CPU with GPU on mobile device. Also we compared the computing time of spring calculation between only CPU and using CPU multi-thread

PBS: Signaling Architecture for Network Traffic Authorization

We present a signaling architecture for network traffic authorization, Permission-Based Sending (PBS). This architecture aims to prevent Denial-of-Service (DoS) attacks and other forms of unauthorized traffic. Towards this goal, PBS takes a hybrid approach: a proactive approach of explicit permissions and a reactive approach of monitoring and countering attacks. On-path signaling is used to configure the permission state stored in routers for a data flow. The signaling approach enables easy installation and management of the permission state, and its use of soft-state improves robustness of the system. For secure permission state setup, PBS provides security for signaling in two ways: signaling messages are encrypted end-to-end using public key encryption and TLS provides hop-by-hop encryption of signaling paths. In addition, PBS uses IPsec for data packet authentication. Our analysis and performance evaluation show that PBS is an effective and scalable solution for preventing various kinds of attack scenarios, including Byzantine attacks

Understanding Continued IT Usage: An Extension to the Expectation-Confirmation Model in IT Domain

A model that has been proposed to investigate the continued IT usage behavior is the Expectation-Confirmation Model in IT Domain (ECM-IT). This paper proposes an extension to the ECM-IT that incorporates perceived ease of use; provide empirical evidence for the utility of the extended ECM-IT; and deepen our knowledge about the factors affecting the continued IT usage behavior. The extended ECM-IT was tested with data collected from 1,826 Mobile Data Services (MDS) users. The LISREL analysis showed that the extended ECM-IT has good explanatory power (R(2) =67%), with perceived ease of use having a stronger impact on user satisfaction and continued usage intention than perceived usefulness. Hence, the extended ECM-IT can provide valuable additional information that is relevant for understanding continued IT usage. The strong impact of perceived ease of use on user satisfaction and intention implies that the nature of the target technology can he an important boundary condition in understanding the continued IT usage behavior. At a more specific level, the extended ECM-IT provides practitioners with deeper insights into how to address customer satisfaction and retention

Intuitive Multilingual Audio-Visual Speech Recognition with a Single-Trained Model

We present a novel approach to multilingual audio-visual speech recognition tasks by introducing a single model on a multilingual dataset. Motivated by a human cognitive system where humans can intuitively distinguish different languages without any conscious effort or guidance, we propose a model that can capture which language is given as an input speech by distinguishing the inherent similarities and differences between languages. To do so, we design a prompt fine-tuning technique into the largely pre-trained audio-visual representation model so that the network can recognize the language class as well as the speech with the corresponding language. Our work contributes to developing robust and efficient multilingual audio-visual speech recognition systems, reducing the need for language-specific models.Comment: EMNLP 2023 Finding

Measurements of Multicast Service Discovery in a Campus

Applications utilizing multicast service discovery protocols, such as iTunes, have become increasingly popular. However, multicast service discovery protocols are considered to generate network traffic overhead, especially in a wireless network. Therefore, it becomes important to evaluate the traffic and overhead caused by multicast service discovery packets in real-world networks. We measure and analyze the traffic of one of the mostly deployed multicast service discovery protocols, multicast DNS (mDNS) service discovery, in a campus wireless network that forms a single multicast domain of large users. We also analyze different service discovery models in terms of packet overhead and service discovery delay under different network sizes and churn rates. Our measurement shows that mDNS traffic consumes about 13 percent of the total bandwidth

The Shape of LITTLE THINGS Dwarf Galaxies DDO 46 and DDO 168: Understanding the stellar and gas kinematics

We present the stellar and gas kinematics of DDO 46 and DDO 168 from the LITTLE THINGS survey and determine their respective Vmax/sigma_z,0 values. We used the KPNO's 4-meter telescope with the Echelle spectrograph as a long-slit spectrograph. We acquired spectra of DDO 168 along four position angles by placing the slit over the morphological major and minor axes and two intermediate position angles. However, due to poor weather conditions during our observing run for DDO 46, we were able to extract only one useful data point from the morphological major axis. We determined a central stellar velocity dispersion perpendicular to the disk, sigma_z,0, of 13.5+/-8 km/s for DDO 46 and of 10.7+/-2.9 km/s for DDO 168. We then derived the maximum rotation speed in both galaxies using the LITTLE THINGS HI data. We separated bulk motions from non-circular motions using a double Gaussian decomposition technique and applied a tilted-ring model to the bulk velocity field. We corrected the observed HI rotation speeds for asymmetric drift and found a maximum velocity, Vmax, of 77.4 +/- 3.7 and 67.4 +/- 4.0 km/s for DDO 46 and DDO 168, respectively. Thus, we derived a kinematic measure, Vmax/sigma_z,0, of 5.7 +/- 0.6 for DDO 46 and 6.3 +/- 0.3 for DDO 168. Comparing these values to ones determined for spiral galaxies, we find that DDO 46 and DDO 168 have Vmax/sigma_z,0 values indicative of thin disks, which is in contrast to minor-to-major axis ratio studies