Stability of a functional equation deriving from cubic and quartic functions

In this paper, we obtain the general solution and the generalized Ulam-Hyers stability of the cubic and quartic functional equation &4(f(3x+y)+f(3x-y))=-12(f(x+y)+f(x-y)) &+12(f(2x+y)+f(2x-y))-8f(y)-192f(x)+f(2y)+30f(2x)

Comparison of spectrum occupancy measurements using software defined radio RTL-SDR with a conventional spectrum analyzer approach

In the present day Cognitive Radio has become a realistic option for solution of the spectrum scarcity problem in wireless communication. Recently, the TV band has attracted attention due to the considerable potential for exploitation of available TV white space which is not utilized based on time and location. In this paper, we investigate spectrum occupancy of the UHF TV band in the frequency range from 470 to 862MHz by using two different devices, the low cost device RTL-SDR and high cost spectrum analyzer. The spectrum occupancy measurements provide evidence of the utility of using the inexpensive RTL SDR and illustrate its effectiveness for detection of the percentage of spectrum utilization compared with results from the conventional high cost Agilent spectrum analyzer, both systems employing various antennas

Spectrum occupancy measurements and lessons learned in the context of cognitive radio

Various measurement campaigns have shown that numerous spectrum bands are vacant even though licenses have been issued by the regulatory agencies. Dynamic spectrum access (DSA) based on Cognitive Radio (CR) has been regarded as a prospective solution to improve spectrum utilization for wireless communications. Empirical measurement of the radio environment to promote understanding of the current spectrum usage of the different wireless services is the first step towards deployment of future CR networks. In this paper we present our spectrum measurement setup and discuss lessons learned during our measurement activities. The main contribution of the paper is to introduce global spectrum occupancy measurements and address the major drawbacks of previous spectrum occupancy studies by providing a unifying methodological framework for future spectrum measurement campaigns

Cooperative wideband spectrum sensing with multi-bit hard decision in cognitive radio

Cognitive radio offers an increasingly attractive solution to overcome the underutilization problem. A sensor network based cooperative wideband spectrum sensing is proposed in this paper. The purpose of the sensor network is to determine the frequencies of the sources and reduced the total sensing time using a multi-resolution sensing technique. The final result is computed by data fusion of multi-bit decisions made by each cooperating secondary user. Simulation results show improved performance in energy efficiency

Experimental detection using cyclostationary feature detectors for cognitive radios

© 2014 IEEE. Signal detection is widely used in many applications. Some examples include Cognitive Radio (CR) and military intelligence. Without guaranteed signal detection, a CR cannot reliably perform its role. Spectrum sensing is currently one of the most challenging problems in cognitive radio design because of various factors such as multi-path fading and signal to noise ratio (SNR). In this paper, we particularly focus on the detection method based on cyclostationary feature detectors (CFD) estimation. The advantage of CFD is its relative robustness against noise uncertainty compared with energy detection methods. The experimental result present in this paper show that the cyclostationary feature-based detection can be robust compared to energy-based technique for low SNR levels

Quality measurements of an UWB reduced-size CPW-fed aperture antenna

The paper presents a characterization of a compact co-planar waveguide (CPW)-fed slot loaded low return loss planar printed antenna designed for wireless communication and ultra-wideband (UWB) applications. Following a review of the antenna design, which was implemented and simulated using Agilent's Advanced Design System (ADS), the paper presents laboratory measurements of relative gain and impulse response transformed from the frequency domain. An antenna quality metric based on time-domain S21 is discussed and related to antenna quality metrics such as the System Fidelity Factor (SFF)

The Simplified-DPNDP_N Approximation of the Neutron Transport Equation

The simplified double-spherical harmonics ($SDP_N$) approximation of the neutron transport equation is proposed. The $SDP_N$ equations are derived from the multi-group $DP_N$ equations for N=1,2,3 (equivalent to the $SP_3$, $SP_5$, and $SP_7$ equations, respectively), and are converted into the form of second order multi-group diffusion equations. The finite element method is then used to numerically solve these equations. The computational performance of the $SDP_N$ method is compared with the $SP_N$ on several fixed-source and criticality test problems. The results show that the $SDP_N$ formulation generally calculates parameters like criticality eigenvalue, disadvantage factors, absorption rate, etc. more accurately than the $SP_N$, while the computational effort is the same for both methods.Comment: 20 pages, 9 figures, 11 table

DOCUMENTATION OF THE DOCUMENTATIONS OF THE KING OF THE KINGS

Documentations made by Dariush I, King of the Kings, the great emperor of Persia (500 BC) are the largest inscriptions in the world including 1200 lines of about 2 meters length. These inscriptions written in Old Persian, that were simultaneously translated into Elamite and Babylonian, narrate the victories of Dariush over the rebellious rulers of the kingdom. This magnificent monument is carved on the stone wall of the holy mount of Bisotun in the western part of Iran. The monument was made at a height of about 80 meters above the road which made it almost impossible for anybody to get access to it. There has been a tendency since 450 years ago to decode these texts and record the relieves. In 1834, Rawlinson, hanging himself form the top of the mount, attempted to make a hand-recording and decoding of the entire monument which lasted 20 years. He could finally decode the old Persian language for the first time. Following this work, Thompson and Cameron tried to perform some restoration and correction works by means of photography and moulding. The new stage of this documentation process is the photogrammetric technique. For a long time, the photogrammetric documentation of this valuable and unique monument was investigated and desired by the authorities of the Iranian Organization of Cultural Heritage, but the dangerous situation of this monument that made the geodetic and photogrammetric operation very difficult, was a major reason for Iranian and foreign companies to not accept the photogrammetric documentation of this monument. This paper gives a scientific report on how this great job of “ Documentation “ was done within an academic project. All relieves, more than 120000 elements of the inscriptions and the surrounding objects and area were photogrammetrically documented and recorded with a precision of about 1 mm

Generalized relation between the relative entropy and dissipation for nonequilibrium systems

Recently, Kawai, Parrondo, and Van den Broeck have related dissipation to time-reversal asymmetry. We generalized the result by considering a protocol where the physical system is driven away from an initial thermal equilibrium state with temperature $\beta_0$ to a final thermal equilibrium state at a different temperature. We illustrate the result using a model with an exact solution, i.e., a particle in a moving one-dimensional harmonic well.Comment: 4 page