Power Estimation Algorithm Research Articles

Development of an improved framework for the conceptual design of a rotorcraft

Purpose – The purpose of the present paper is to obtain the capability of designing modern rotorcrafts with enhanced accuracy and reliability. Design/methodology/approach – Among the existing rotorcraft design programs, an appropriate program was selected as a baseline for improvement. It was based on a database comprising conventional fleets of rotorcrafts. The baseline program was not robust because it contained a simple iteration loop, which only monitored the gross weight of the aircraft. Therefore, it is not accurate enough to fulfill the quality and sophistication of a conceptual design framework useful for present and future generations of rotorcrafts. In this paper, the estimation formulas for the sizing and weight of the rotorcraft subsystem were updated by referring to modern aircraft data. In addition, trend curves for various turboshaft engines available these days were established. Instead of using the power estimation algorithm based on the momentum theory with empirical corrections, blade e...

Corneal power estimation for intraocular lens power calculation after corneal laser refractive surgery in Chinese eyes

To develop and evaluate an algorithm for corneal power estimation in intraocular lens (IOL) power calculation after corneal laser refractive surgery in Chinese eyes. Guangdong Eye Institute, Guangdong Academy of Medical Sciences, Guangzhou, China. Prospective comparative case series. Corneal parameters in Chinese eyes and German eyes were measured using a rotating Scheimpflug camera. Corneal power was simplified as a corrective algorithm: K(C) = 1.114 × K(M) + K(2) (K(M) = measured K reading; K(2) = K(P) - K(A) × K(P) × CT/1.376; K(A) = anterior corneal power; K(P) = posterior corneal power; CCT = central corneal thickness). The variation and change in K(2) induced by refractive surgery were analyzed in Chinese eyes. The corrective algorithm was identified as K(C) = 1.114 × K(M) - 6.20. The method was evaluated in Chinese cataract cases after refractive surgery using the Haigis formula. No difference in anterior corneal radius (R(A)) or CCT between Chinese eyes and German eyes were found; however, the posterior corneal radius (R(P)), R(A)/R(P) ratio, keratometric index, and K(2) were different. The mean K(2) was -6.23 diopters (D) ± 0.24 (SD) in Chinese eyes and -6.12 ± 0.23 D in German eyes (P<.01). The mean change in K(2) induced by refractive surgery was -0.02 ± 0.06 D. The median absolute prediction error in IOL power calculation was 0.43 D (range 0.01 to 1.80 D). The algorithm was a relatively reliable method in IOL power calculation after corneal refractive surgery in Chinese eyes.

Load balancing algorithm by vertical handover for integrated heterogeneous wireless networks

In this paper, an adaptive resource management scheme for hybrid WWAN/WLAN is proposed. Based on proposed joint velocity and average received power (ARP) estimation algorithms, a novel vertical handoff (VHO) for efficient load balancing in multitier network is developed. Simulation results show that proposed scheme achieves significant improvements over conventional schemes.

Efficient Parallel Implementation of State Estimation Algorithms on Multicore Platforms

For many applications in signal processing and control it is crucial that estimates of the state vector in a dynamic system can be obtained in real time. This poses the problem of producing algorithms that are fast enough to enable online execution. In this article, it is investigated how two of the most popular and powerful state estimation algorithms, the Kalman filter and the particle filter, can be efficiently implemented in parallel on a multicore architecture. The proposed parallel implementations are analyzed in terms of hardware requirements, such as memory bandwidth and available cache memory, to provide the desired speedup. The algorithms are exemplified by and evaluated in an adaptive filtering and a bearings-only tracking application. In the cases when original algorithms have been modified for parallelization, the accuracy of the estimates obtained is evaluated in comparison with that of the sequential algorithm. It is found that linear speedup, in the number of cores used, can indeed be achieved without loss of accuracy, for both state estimation algorithms.

Analysis of Optimal Weighted Cooperative Spectrum Sensing with Multiple Antenna Elements

This paper investigates the use of cooperative spectrum sensing (CSS) to detect primary user (PU) signals during spectrum sharing between the PU and the secondary user (SU). In particular, we employ a variant of CSS (which achieves space diversity), called weighted gain combining CSS (W-CSS), which has the potential to achieve increased diversity gain and enhance detection performance. In a typical W-CSS system, the SU needs to obtain the PU signal power information in order to set the proper weight value. However, as it is hard for the SU to ascertain whether the PU is present or absent, this is difficult to obtain. To address this problem, a PU signal power estimation algorithm is introduced. In addition, we also analyze the statistics of the estimator and derive the detection probability of the W-CSS when the PU signal power estimation algorithm is applied. The analysis and related simulation results reveal that the detection probability of the proposed W-CSS under time-variant Rayleigh fading asymptotically approaches the detection probability in an additive white Gaussian noise channel as the number of antennas is increased. This also follows results from our Monte Carlo simulations, showing that multiple antenna elements could suppress the effect of Rayleigh fading. In short, the accuracy of the estimation algorithm is affected by channel variation (especially in the case of fast Rayleigh fading). Hence, to address this problem, we employ multiple antenna elements with a square-law combining energy detector in the W-CSS. key words: cognitive radio, cooperative spectrum sensing, NeymanPearson theorem, multiple antenna elements

Performance Analysis of Simultaneous Location and Power Estimation Using WLS Method for Cognitive Radio

Precise estimation of spatial spectrum holes is of great importance in future cognitive radio (CR) networks. This information can help the secondary users to employ the spatial resources more efficiently and limit the interference to the primary users to the admissible level. In order to measure the performance of a location and power estimation algorithm, obtaining the statistical characteristics of estimation error is of great importance. In this paper, the performance of RSS-WLS approach which is an important linear position and power estimation algorithm in cognitive radio systems has been analyzed by obtaining the closed form expression for mean and covariance of its estimation error.

Predictive Power Estimation Algorithm (PPEA) - A New Algorithm to Reduce Overfitting for Genomic Biomarker Discovery

Toxicogenomics promises to aid in predicting adverse effects, understanding the mechanisms of drug action or toxicity, and uncovering unexpected or secondary pharmacology. However, modeling adverse effects using high dimensional and high noise genomic data is prone to over-fitting. Models constructed from such data sets often consist of a large number of genes with no obvious functional relevance to the biological effect the model intends to predict that can make it challenging to interpret the modeling results. To address these issues, we developed a novel algorithm, Predictive Power Estimation Algorithm (PPEA), which estimates the predictive power of each individual transcript through an iterative two-way bootstrapping procedure. By repeatedly enforcing that the sample number is larger than the transcript number, in each iteration of modeling and testing, PPEA reduces the potential risk of overfitting. We show with three different cases studies that: (1) PPEA can quickly derive a reliable rank order of predictive power of individual transcripts in a relatively small number of iterations, (2) the top ranked transcripts tend to be functionally related to the phenotype they are intended to predict, (3) using only the most predictive top ranked transcripts greatly facilitates development of multiplex assay such as qRT-PCR as a biomarker, and (4) more importantly, we were able to demonstrate that a small number of genes identified from the top-ranked transcripts are highly predictive of phenotype as their expression changes distinguished adverse from nonadverse effects of compounds in completely independent tests. Thus, we believe that the PPEA model effectively addresses the over-fitting problem and can be used to facilitate genomic biomarker discovery for predictive toxicology and drug responses.

Intraocular lens power calculation after laser refractive surgery: Corrective algorithm for corneal power estimation

To evaluate an algorithm for corneal power estimation in intraocular lens (IOL) power calculation after myopic laser refractive surgery using direct corneal measurements. International Vision Correction Research Centre, University of Heidelberg, Heidelberg, Germany. Corneal parameters in normal eyes and eyes of refractive surgery cases were evaluated by rotating Scheimpflug imaging. Corneal optical power (K(optical)) calculated by a Gaussian optics formula was simplified as K(optical) = K(anterior) + K(2) (K(anterior) = anterior corneal power; K(posterior) = posterior corneal power; K(2) = K(posterior)--K(anterior) x K(posterior) x corneal thickness/1.376). The variation and change in K(2) induced by refractive surgery were analyzed. A corrective algorithm to calculate K(optical) using mean K(2) (-6.10 diopters [D]), K(corrective) = 1.114 x measured K - 6.10, was derived based on statistical analysis, which was in accordance with the modified Maloney method. The IOL power after refractive surgery was calculated using K(corrective). The mean K(2) of normal and post-refractive corneas was -6.10 +/- 0.23 D and -6.16 +/- 0.17 D, respectively (P = .17). The mean refractive surgery-induced change in K(2) was -0.06 +/- 0.10 D. The variations in K(2) were small (95% confident interval, -6.55 to -5.65 [normal cornea]; -6.48 to -5.70 [pre-refractive]; - 6.49 to -5.83 [post-refractive)]. Using K(corrective) for IOL power calculation in post-refractive cases yielded mean absolute prediction errors of 0.58 +/- 0.52 D (Haigis), 0.59 +/- 0.49 D (double-K Hoffer Q), and 0.58 +/- 0.47 D (double-K SRK/T). The algorithm that induced low error in corneal power estimation was relatively reliable in IOL calculation after myopic laser refractive surgery. No author has a financial or proprietary interest in any material or method mentioned.

An Improved Power Estimation for Mobile Satellite Communication Systems

In this paper, in order to increase system capacity and reduce the transmitting power of the user's equipment, we propose a efficient power estimation algorithm consisting of a modified open-loop power control (OLPC) and closed-loop power control (CLPC) for mobile satellite communications systems. The improved CLPC scheme, combining delay compensation algorithms and pilot diversity, is mainly applied to the ancillary ter-restrial component (ATC). ATC link in urban areas, because it is more suitable to the short round-trip delay (RTD). In the case of rural areas, where ATCs are not deployed or where a signal is not received from ATCs, transmit power monitoring equipment and OLPC schemes using efficient pilot diversity are combined and ap-plied to the link between the user's equipment and the satellite. Two modified power control schemes are ap-plied equally to the boundary areas where two kinds of signals are received in order to ensure coverage conti-nuity. Simulation results show that the improved power control scheme has good performance compared to conventional power control schemes in a geostationary earth orbit (GEO) satellite system utilizing ATCs.

Extraction of a quantitative reaction mechanism from linear sweep voltammograms obtained on a rotating disk electrode. Part I: Theory and validation

In this work a method is set-up to extract the mass and charge transfer parameters quantitatively from linear sweep voltammetry with a rotating disc electrode (LSV/RDE) experiments. It requires the proposition of an appropriate mechanism for the reaction under study and its mathematical translation into an expression that analytically describes the voltammogram. Powerful parameter estimation algorithms (maximum likelihood combined with Gauss–Newton and Levenberg–Marquardt minimization methods) are used to adjust the values of these model parameters, in order to obtain a good agreement between experimental and modeled data. The values of the model parameters that give rise to the best match, characterize the system quantitatively. Moreover, the method provides error estimates of the obtained parameter values. However it is only after a statistical evaluation of the obtained results, that it is decided whether the model is able to describe the experiments or not. Compared to others, this method offers the advantage that it uses one integrated expression that accounts for mass and charge transfer steps, and this without simplifying their mathematical expressions. Other elementary reaction steps (like chemical reactions, migration, adsorption) can also be included, as long as their influence on the polarization curve is mathematically formulated. Another plus-point is that the whole polarization curve is considered, rather then just some part in which only mass or charge transfer are supposed to be rate determining. This approach has never before been used in electrochemical studies and the coupling of statistically founded parameter estimation techniques with LSV/RDE experiments is an important innovative point of this work. In the first article of this series the theoretical background is described. Furthermore, an evaluation of the proposed method on simulated experiments is given at the end of this manuscript.

Blind estimation of modulation schemes according to noise powers in the presence of carrier frequency offset

AbstractA method for identifying modulation schemes is a vital elemental technology of adaptive software‐defined radio that switches its software in response to the environment and the application objective. The problems faced in conventional modulation scheme estimation are synchronization and robustness in a fading environment. In this paper, we address the problem of the degradation in the accuracy of modulation scheme estimation due to the presence of carrier offsets and the fluctuations in the carrier‐to‐noise power ratio (CNR). The former is addressed by implementing offset cancellation that uses the temporal phase difference information in one symbol. The latter is addressed by using the estimates found by a blind noise power estimation algorithm to implement modulation scheme estimation that exhibits excellent estimation accuracy even with a fluctuating CNR. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 85(12): 76–88, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10001