Distributions of Upper PAPR and Lower PAPR of OFDM Signals in Visible Light Communications

Orthogonal frequency-division multiplexing (OFDM) in visible light communications (VLC) inherits the disadvantage of high peak-to-average power ratio (PAPR) from OFDM in radio frequency (RF) communications. The upper peak power and lower peak power of real-valued VLC-OFDM signals are both limited by the dynamic constraints of light emitting diodes (LEDs). The efficiency and transmitted electrical power are directly related with the upper PAPR (UPAPR) and lower PAPR (LPAPR) of VLC-OFDM. In this paper, we will derive the complementary cumulative distribution function (CCDF) of UPAPR and LPAPR, and investigate the joint distribution of UPAPR and LPAPR.Comment: acceptted by IEEE ICASSP 2014. arXiv admin note: text overlap with arXiv:1304.019

Scene-Based Nonuniformity Correction with Reduced Ghosting Using a Gated LMS Algorithm

In this paper, we present a scene-based nouniformity correction (NUC) method using a modified adaptive least mean square (LMS) algorithm with a novel gating operation on the updates. The gating is designed to significantly reduce ghosting artifacts produced by many scene-based NUC algorithms by halting updates when temporal variation is lacking. We define the algorithm and present a number of experimental results to demonstrate the efficacy of the proposed method in comparison to several previously published methods including other LMS and constant statistics based methods. The experimental results include simulated imagery and a real infrared image sequence. We show that the proposed method significantly reduces ghosting artifacts, but has a slightly longer convergence time

Factors Influencing Northern Bobwhite Hunter Success on a Public Wildlife Management Area in Kentucky

Hunter success is a critical measure of northern bobwhite (Colinus virginianus) restoration. Understanding the factors influencing hunter success can guide wildlife agencies in efforts to improve success and satisfaction and sustain hunter support of conservation initiatives. We compared use of vegetation types by radiomarked bobwhite (n = 30 coveys) and hunting dogs (n = 241) equipped with Global Positioning System collars during the 2014–2015 quail hunting season on Peabody Wildlife Management Area in western Kentucky. We surveyed hunting parties (n = 252) immediately after their hunt to determine success (flushed bobwhite) and gather hunt-party characteristics. We used associated habitat metrics from the dog track, weather variables, hunter and dog characteristics (e.g., age, experience), and hunt metrics (e.g., hours hunted, no. of dogs) to determine factors that influenced hunt success. Dogs used winter wheat firebreaks more than bobwhite regardless of time of day, forested areas more than bobwhite in the morning (0700–1000 hr) and midday (1000–1300 hr), disked areas more than bobwhite during midday, and open herbaceous areas less than bobwhite during morning and midday. The probability of success was positively influenced by number of dogs and hours hunted and negatively influenced by proportion of the hunt track in disked areas. Also, hunter success was greater in November compared with December and January. Our results indicated some key features associated with bobwhite habitat (open areas) may be underexploited by hunters, whereas other features (disked areas, firebreaks, and forested areas) may be overexploited. However, success was influenced primarily by factors that may be related to covey avoidance behavior resulting from substantial hunting pressure rather than where hunters selected to hunt. Lower bobwhite encounter rates (coveys flushed/hour) could cause hunter support to wane and bias hunting data as an indicator of population abundance

Numerical Approximations Using Chebyshev Polynomial Expansions

We present numerical solutions for differential equations by expanding the unknown function in terms of Chebyshev polynomials and solving a system of linear equations directly for the values of the function at the extrema (or zeros) of the Chebyshev polynomial of order N (El-gendi's method). The solutions are exact at these points, apart from round-off computer errors and the convergence of other numerical methods used in connection to solving the linear system of equations. Applications to initial value problems in time-dependent quantum field theory, and second order boundary value problems in fluid dynamics are presented.Comment: minor wording changes, some typos have been eliminate