Co-projection-plane based 3-D padding for polyhedron projection for 360-degree video

The polyhedron projection for 360-degree video is becoming more and more popular since it can lead to much less geometry distortion compared with the equirectangular projection. However, in the polyhedron projection, we can observe very obvious texture discontinuity in the area near the face boundary. Such a texture discontinuity may lead to serious quality degradation when motion compensation crosses the discontinuous face boundary. To solve this problem, in this paper, we first propose to fill the corresponding neighboring faces in the suitable positions as the extension of the current face to keep approximated texture continuity. Then a co-projection-plane based 3-D padding method is proposed to project the reference pixels in the neighboring face to the current face to guarantee exact texture continuity. Under the proposed scheme, the reference pixel is always projected to the same plane with the current pixel when performing motion compensation so that the texture discontinuity problem can be solved. The proposed scheme is implemented in the reference software of High Efficiency Video Coding. Compared with the existing method, the proposed algorithm can significantly improve the rate-distortion performance. The experimental results obviously demonstrate that the texture discontinuity in the face boundary can be well handled by the proposed algorithm.Comment: 6 pages, 9 figure

Interest Rate Caps Smile Too! But Can the LIBOR Market Models Capture It?

Using more than two years of daily interest rate cap price data, this paper provides a systematic documentation of a volatility smile in cap prices. We find that Black (1976) implied volatilities exhibit an asymmetric smile (sometimes called a sneer) with a stronger skew for in-the-money caps than out-of-the-money caps. The volatility smile is time varying and is more pronounced after September 11, 2001. We also study the ability of generalized LIBOR market models to capture this smile. We show that the best performing model has constant elasticity of variance combined with uncorrelated stochastic volatility or upward jumps. However, this model still has a bias for short- and medium-term caps. In addition, it appears that large negative jumps are needed after September 11, 2001. We conclude that the existing class of LIBOR market models can not fully capture the volatility smileLIBOR market models, volatility smile, interest rate caps

Computer-Aided Design of Coupler-Driven Watt I and Tolerance Synthesis for Four-Bar Linkages

Theory to rectify circuit defects in rocker-crank and double-rocker at the synthesis level is described based on the angular joint displacements. It complements the crank-rocker and double-crank circuit rectification to complete the circuit rectification of four-bar linkages. The procedure utilizes the algebraic method where special points followed by a line construction procedure are employed to validate the range of the critical angle that can identify the circuit defects as a function of the design positions prior to the completion of the linkage. A complete procedure of the rectified synthesis of the coupler-driven Watt I six-bar linkage to pass through the pre-defined four design positions is presented. This is done by de-coupling the six-bar mechanism as a coupler-driven and crank-driven four-bar linkages with common links. The vector component mechanism modeling method is applied to these linkages where the dyad and triad synthesis approaches are adopted in conjunction with the vector-algebraic method to find the solutions. The linkage with the coupler-driver is initially synthesized and rectified, then followed by the crank-driven four-bar linkage. The six-bar linkage is thus insured to assemble free of circuit, branch, and order defects. Optimization techniques are used to render the best solution linkages according to the specified design criteria. The process is coded and added to a mechanism design platform--RECSYN that allows a designer to synthesize coupler-driven Watt I linkages and the new circuit rectification theory is also applied in the program. A methodology to determine the optimum link length tolerance and joint clearance distributions in four-bar linkages for motion generation with specified structural error in order to manufacture the linkages is proposed. A stochastic model incorporated with tolerances and clearances for four-bar motion generation is proposed. The statistical characteristics of the random variables in the model are discussed. The mechanical error of four-bar motion generation as a function of statistical properties of random variables is defined. The tolerances and clearances are obtained as a result of solving an optimization problem with the objective function of link length tolerances and joint clearances and structural error as constraints. A FORTRAN code is written based on the proposed theory and ADS is employed as an optimization design tool. With this program, optimum link length tolerance and joint clearance distribution can be computed when the user input the required linkage information and structural errors. Examples of assigning tolerance and clearance for four-bar motion generation are presented to demonstrate the application of the method

Algorithms on Minimizing the Maximum Sensor Movement for Barrier Coverage of a Linear Domain

In this paper, we study the problem of moving $n$ sensors on a line to form a barrier coverage of a specified segment of the line such that the maximum moving distance of the sensors is minimized. Previously, it was an open question whether this problem on sensors with arbitrary sensing ranges is solvable in polynomial time. We settle this open question positively by giving an $O(n^2 \log n)$ time algorithm. For the special case when all sensors have the same-size sensing range, the previously best solution takes $O(n^2)$ time. We present an $O(n \log n)$ time algorithm for this case; further, if all sensors are initially located on the coverage segment, our algorithm takes $O(n)$ time. Also, we extend our techniques to the cycle version of the problem where the barrier coverage is for a simple cycle and the sensors are allowed to move only along the cycle. For sensors with the same-size sensing range, we solve the cycle version in $O(n)$ time, improving the previously best $O(n^2)$ time solution.Comment: This version corrected an error in the proof of Lemma 2 in the previous version and the version published in DCG 2013. Lemma 2 is for proving the correctness of an algorithm (see the footnote of Page 9 for why the previous proof is incorrect). Everything else of the paper does not change. All algorithms in the paper are exactly the same as before and their time complexities do not change eithe

The economic impact of credit default swap on credit markets

This study conducts a comprehensive analysis of the economic benefits and costs of credit default swap (CDS) in credit markets since its inception. Consistent with its role of insuring credit risk, the introduction of CDS reduces illiquidity and liquidity risk more for speculative grade bonds with high credit risk than investment grade ones. More importantly, CDS significantly improves the price convergence between investment grade bonds and CDS spreads through a popular trading strategy—CDS-bond basis arbitrage in normal period. In the recent crisis, however, CDS fails to reduce the prolonged price divergence between the two markets plausibly due to the lack of arbitrage. Overall, the economic impact of CDS is dependent on the prevailing trading strategies in the credit markets

Actively controlling the topological transition of dispersion based on electrically controllable metamaterials

Topological transition of the iso-frequency contour (IFC) from a closed ellipsoid to an open hyperboloid, will provide unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive and the related experimental observations are highly desirable. Here, tunable electric IFC in periodic structure which is composed of graphene/dielectric multilayers is investigated by tuning the chemical potential of graphene layer. Specially, we present the actively controlled transportation in two kinds of anisotropic zero-index media containing PEC/PMC impurities. At last, by adding variable capacitance diodes into two-dimensional transmission-line system, we present the experimental demonstration of the actively controlled magnetic topological transition of dispersion based on electrically controllable metamaterials. With the increase of voltage, we measure the different emission patterns from a point source inside the structure and observe the phase-transition process of IFCs. The realization of actively tuned topological transition will opens up a new avenue in the dynamical control of metamaterials.Comment: 21 pages,8 figure

Forecasting Popularity of Videos using Social Media

This paper presents a systematic online prediction method (Social-Forecast) that is capable to accurately forecast the popularity of videos promoted by social media. Social-Forecast explicitly considers the dynamically changing and evolving propagation patterns of videos in social media when making popularity forecasts, thereby being situation and context aware. Social-Forecast aims to maximize the forecast reward, which is defined as a tradeoff between the popularity prediction accuracy and the timeliness with which a prediction is issued. The forecasting is performed online and requires no training phase or a priori knowledge. We analytically bound the prediction performance loss of Social-Forecast as compared to that obtained by an omniscient oracle and prove that the bound is sublinear in the number of video arrivals, thereby guaranteeing its short-term performance as well as its asymptotic convergence to the optimal performance. In addition, we conduct extensive experiments using real-world data traces collected from the videos shared in RenRen, one of the largest online social networks in China. These experiments show that our proposed method outperforms existing view-based approaches for popularity prediction (which are not context-aware) by more than 30% in terms of prediction rewards