Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)

Since its invention, the phasor has essentially been considered as a steady-state concept. Up to now, this assumption has shaped most of the algorithms for phasor estimation. This paper breaks that old paradigm by relaxing the static phasor concept to a dynamic one, i.e., the dynamic phasor, which is one complex time function with movement freedom. This paper presents the algorithm to approximate the dynamic phasor by a second-order Taylor polynomial and compares its phasor estimate to the traditional one. This approximation leads to the definition of the phasor state vector, which contains not only the estimate of the dynamic phasor but the estimates of its derivatives as well. These new estimates improve the accuracy of oscillation estimation by including new Taylor details into the interpolation process. Errors on the order of 10-4 are achieved with this approximation in bandpass signals over observation intervals of two cycles.

Dynamic Phasor Estimates for Power System Oscillations

Twitter has been used as one of the communication channels for spreading breaking news. We propose a method to collect, group, rank and track breaking news in Twitter. Since short length messages make similarity comparison difficult, we boost scores on proper nouns to improve the grouping results. Each group is ranked based on popularity and reliability factors. Current detection method is limited to facts part of messages. We developed an application called “Hotstream” based on the proposed method. Users can discover breaking news from the Twitter timeline. Each story is provided with the information of message originator, story development and activity chart. This provides a convenient way for people to follow breaking news and stay informed with real-time updates.

Breaking News Detection and Tracking in Twitter.

We describe the design of finite-size linear-phase separable kernels for differentiation of discrete multidimensional signals. The problem is formulated as an optimization of the rotation-invariance of the gradient operator, which results in a simultaneous constraint on a set of one-dimensional low-pass prefilter and differentiator filters up to the desired order. We also develop extensions of this formulation to both higher dimensions and higher order directional derivatives. We develop a numerical procedure for optimizing the constraint, and demonstrate its use in constructing a set of example filters. The resulting filters are significantly more accurate than those commonly used in the image and multidimensional signal processing literature.

/pdf/differentiation-of-discrete-multidimensional-signals-554aesbafm.pdf

Differentiation of discrete multidimensional signals

In this article, we provide a detailed survey of 3D Morphable Face Models over the 20 years since they were first proposed. The challenges in building and applying these models, namely, capture, modeling, image formation, and image analysis, are still active research topics, and we review the state-of-the-art in each of these areas. We also look ahead, identifying unsolved challenges, proposing directions for future research, and highlighting the broad range of current and future applications.

/pdf/3d-morphable-face-models-past-present-and-future-33bjgatyz8.pdf

3D Morphable Face Models—Past, Present, and Future

Virtual try-on of clothes has received much attention recently due to its commercial potential. It can be used for online shopping or intelligent recommendation to narrow down the selections to a few designs and sizes. In this paper, we present a mixed reality system for 3D virtual clothes try-on that enables a user to see herself wearing virtual clothes while looking at a mirror display, without taking off her actual clothes. The user can select various virtual clothes for trying-on. The system physically simulates the selected virtual clothes on the user's body in real-time and the user can see virtual clothes fitting on the her mirror image from various angles as she moves. The major contribution of this paper is that we automatically customize an invisible (or partially visible) avatar based on the user's body size and the skin color and use it for proper clothes fitting, alignment and clothes simulation in our virtual try-on system. We present three scenarios: i) virtual clothes on the avatar, ii) virtual clothes on the user's image and iii) virtual clothes on the avatar blended with the user's face image. We have conducted a user study to evaluate the effectiveness of these three solutions from the end user's perception of quality attributes, cognitive attributes and attitude towards using. The user study shows that among these three scenarios, the second one is most preferred by the users and for 50% of them the experience they had with our system was sufficient to make the purchase decision for the outfits they virtually tried-on.

A Mixed Reality Virtual Clothes Try-On System

High-dynamic-range (HDR) images require tone mapping to be displayed properly on lower dynamic range devices. In this paper, a tone-mapping algorithm that uses histogram of luminance to construct a lookup table (LUT) for tone mapping is presented. Characteristics of the human visual system (HVS) are used to give more importance to visually distinguishable intensities while constructing the histogram bins. The method begins with constructing a histogram of the luminance channel, using bins that are perceived to be uniformly spaced by the HVS. Next, a refinement step is used, which removes the pixels from the bins that are indistinguishable by the HVS. Finally, the available display levels are distributed among the bins proportionate to the pixels counts thus giving due consideration to the visual contribution of each bin in the image. Quality assessment using both quantitative evaluations and user studies suggests that the presented algorithm produces tone-mapped images that are visually pleasant and preserve details of the original image better than the existing methods. Finally, implementation details of the algorithm on GPU for parallel processing are presented, which could achieve a significant gain in speed over CPU-based implementation.

A Tone-Mapping Technique Based on Histogram Using a Sensitivity Model of the Human Visual System

Closed-form expressions for the finite approximations of first and higher derivatives based on Taylor series

The classical central difference approximations of derivative of a function based on Taylor series are the same as type III maximally linear digital differentiators for low frequencies. A new finite difference formula is derived, which can be implemented as a fullband type IV maximally linear differentiator. The differentiator is compared with type III maximally linear and type IV equiripple minimax differentiators. A modification is proposed in the design to minimise the region of inaccuracy near the Nyquist frequency edge.

New design of full band differentiators based on Taylor series

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.149.7922&rep=rep1&type=pdf

Ishtiaq Rasool Khan

Papers

A Mixed Reality Virtual Clothes Try-On System

A Tone-Mapping Technique Based on Histogram Using a Sensitivity Model of the Human Visual System

Closed-form expressions for the finite approximations of first and higher derivatives based on Taylor series

New design of full band differentiators based on Taylor series

Taylor series based finite difference approximations of higher-degree derivatives