Design Space Exploration of Galois and Fibonacci Configuration based on Espresso Stream Cipher

Galois and Fibonacci are two different configurations of stream ciphers. Because the Fibonacci configuration is more convenient for cryptanalysis, most ciphers are designed as Fibonacci-configured. So far, although many transformations between Fibonacci and Galois configurations have been proposed, there is no sufficient analysis of their respective hardware performance. The 128-bit secret key stream cipher Espresso, its Fibonacciconfigured variant and linear Fibonacci variant have a similar security level. We take them as examples to design the optimization strategies in terms of both area and throughput, investigate which configuration is more efficient in a certain aspect. The Fibonacci-configured Espresso occupies 52 slices on Spartan-3 and 22 slices on Virtex-7, which are the minimum solutions among those three Espresso schemes or even smaller than 80-bit secret key ciphers. Based on our throughput improvement strategy, parallel Espresso design can perform 4.1 Gbps on Virtex-7 FPGA and 1.9 Gbps on Spartan-3 FPGA at most. In brief, the Fibonacci cipher is more suitable for extremely resource-constrained or extremely high-throughput applications, while the Galois cipher seems like a compromise between area and speed. Besides, the transformation from nonlinear feedback to linear feedback is not recommended for any hardware implementations

Dynamic response analysis of the rotating blade of horizontal axis wind turbine

This paper presents a dynamic response analysis of the blade of horizontal axis wind turbines using finite element method. The blade is treated as a cantilever and modeled with two-node beam element. The blade element-momentum theory is applied to calculate the aerodynamic loads. Dynamic inflow and dynamic stall are taken into account to reflect the transient aerodynamics. The centrifugal stiffening is introduced to consider the restoring effects of centrifugal force. An aerodynamic damping model is presented for calculating the overall damping ratio instantaneously during time-domain simulation. The structural dynamic equation is solved using Newmark method and the overall dynamic response of the blade is obtained based on the modal superposition principle. Applying the proposed method, the power production load case of a 1.0 MW wind turbine operating in turbulent wind field is simulated. The simulation results indicate that the blades of large-scale horizontal axis wind turbines undergo significant vibration and deflection during operation, and the centrifugal stiffening and aerodynamic damping both considerably affect the structural response of the blade

Effects of aerodynamic damping on the tower load of offshore horizontal axis wind turbines

Aerodynamic damping has an important effect on the dynamic response of offshore Horizontal Axis Wind Turbines (HAWTs). In this paper, an analysis of the loads on offshore HAWTs is presented. The analysis combines the aerodynamics, hydrodynamics and structural dynamics of the structure, and includes the effects of aerodynamic damping. The aim is to better understand the role of aerodynamic damping during the interaction of wind and wave and the structure, and to quantitatively evaluate the effects of aerodynamic damping on the lifetime fatigue load on offshore HAWT towers. The aerodynamic loads are estimated using the Blade Element-Momentum (BEM) theory, including the effects of dynamic inflow and dynamic stall. The wave dynamics is estimated assuming \u27random sea state\u27 described by the JONSWAP spectrum, with wave loads calculated using Morison\u27s equation and water kinematics modelled using linear wave theory. Two aerodynamic damping models are proposed: (1) a model based on the analysis of the rotor aerodynamics incorporating the tower-top motion of a constant-speed wind turbine, which is then modified for variable-speed wind turbines by introducing a correction factor; and (2) a model based on Salzmann and van der Tempel\u27s method (Salzmann and van der Tempel, 2005) to calculate the aerodynamic damping as the increase in the thrust per unit increase in the wind speed. The models are incorporated into a transient load analysis. The effects of aerodynamic damping on the lifetime fatigue loads of the tower are then investigated through load analysis of a 5 MW offshore HAWT. In addition, the influence of different aerodynamic damping calculation methods on the prediction of fatigue loads is studied

Tower Load Analysis of Offshore Wind Turbines and the Effects of Aerodynamic Damping

This study presents an analysis of the loads on offshore Horizontal Axis Wind Turbines (HAWTs). The aerodynamic loads are estimated using the Blade Element-Momentum (BEM) theory, including the effects of dynamic inflow and dynamic stall. The wave loads are calculated using Morison\u27s equation. Models are proposed to account for the effects of aerodynamic damping on the fatigue loading on the tower during its working lifetime. Load analysis of a 5 MW offshore HAWT is carried out and the influence of aerodynamic damping on the fatigue load is investigated

Common Fixed Point Theorems in a New Fuzzy Metric Space

We generalize the Hausdorff fuzzy metric in the sense of Rodríguez-López and Romaguera, and we introduce a new M∞-fuzzy metric, where M∞-fuzzy metric can be thought of as the degree of nearness between two fuzzy sets with respect to any positive real number. Moreover, under ϕ-contraction condition, in the fuzzy metric space, we give some common fixed point theorems for fuzzy mappings

Petrogenesis and Geodynamic Implications of Miocene Felsic Magmatic Rocks in the Wuyu Basin, Southern Gangdese Belt, Qinghai-Tibet Plateau

Miocene felsic magmatic rocks with high Sr/Y ratios are widely distributed throughout the Gangdese belt of southern Tibet. These provide a good opportunity to explore the magmatic process and deep dynamic mechanisms that occurred after collision between the Indo and the Asian plates. In this paper, felsic volcanic rocks from the Zongdangcun Formation in the Wuyu Basin in the central part of the southern Gangdese belt are used to disclose their origin. Zircon U-Pb geochronology analysis shows that the felsic magmatism occurred at ca. 10.3 ± 0.2 Ma, indicating that the Zongdangcun Formation formed during the Miocene. Most of these felsic magmatic rocks plot in the rhyolite area in the TAS diagram. The rhyolite specimens from the Zongdangcun Formation have the characteristics of high SiO2 (>64%), K2O, SiO2, and Sr contents, a low Y content and a high Sr/Y ratio, and the rocks are rich in LREE and depleted in HREE, showing geochemical affinity to adakitic rocks. The rocks have an enriched Sr-Nd isotopic composition (εNd(t) = −6.76 to −6.68, (87Sr/86Sr)i = 0.7082–0.7088), which is similar to the mixed product of the juvenile Lhasa lower continental crust and the ancient Indian crust. The Hf isotopes of zircon define a wide compositional range (εHf(t) = −4.19 to 6.72) with predominant enriched signatures. The Miocene-aged crustal thickness in southern Tibet, calculated on the basis of the Sr/Y and (La/Yb)N ratios was approximately 60–80 km, which is consistent with the thickening of the Qinghai-Tibet Plateau. The origin of Miocene felsic magmatic rocks with high Sr/Y ratios in the middle section of the Gangdese belt likely involved a partial melting of the thickened lower crust, essentially formed by the lower crust of the Lhasa block, with minor contribution from the ancient Indian crust. After comprehensively analyzing the post-collisional high Sr/Y magmatic rocks (33–8 Ma) collected from the southern margin of the Gangdese belt, we propose that the front edge tearing and segmented subduction of the Indian continental slab may be the major factor driving the east-west trending compositional changes of the Miocene adakitic rocks in southern Tibet

Feature Selection and Transfer Learning for Alzheimer’s Disease Clinical Diagnosis

Background and Purpose: A majority studies on diagnosis of Alzheimer’s Disease (AD) are based on an assumption: the training and testing data are drawn from the same distribution. However, in the diagnosis of AD and mild cognitive impairment (MCI), this identical-distribution assumption may not hold. To solve this problem, we utilize the transfer learning method into the diagnosis of AD. Methods: The MR (Magnetic Resonance) images were segmented using spm-Dartel toolbox and registrated with Automatic Anatomical Labeling (AAL) atlas, then the gray matter (GM) tissue volume of the anatomical region were computed as characteristic parameter. The information gain was introduced for feature selection. The TrAdaboost algorithm was used to classify AD, MCI, and normal controls (NC) data from Alzheimer’s Disease Neuroimaging Initiative (ADNI) database, meanwhile, the “knowledge” learned from ADNI was transferred to AD samples from local hospital. The classification accuracy, sensitivity and specificity were calculated and compared with four classical algorithms. Results: In the experiment of transfer task: AD to MCI, 177 AD and 40NC subjects were grouped as training data; 245 MCI and 45 remaining NC subjects were combined as testing data, the highest accuracy achieved 85.4%, higher than the other four classical algorithms. Meanwhile, feature selection that is based on information gain reduced the features from 90 to 7, controlled the redundancy efficiently. In the experiment of transfer task: ADNI to local hospital data, the highest accuracy achieved 93.7%, and the specificity achieved 100%. Conclusions: The experimental results showed that our algorithm has a clear advantage over classic classification methods with higher accuracy and less fluctuation

An improved dynamic stall model and its effect on wind turbine fatigue load prediction

© 2020 Elsevier Ltd Due to the nature of the atmospheric boundary layer, large Horizontal-Axis Wind Turbines (HAWTs) generally operate in highly unstable environment, leading to nonstationary loads on HAWT structures. Therefore, it is important to accurately estimate the nonstationary loads to ensure appropriate design boundaries. In this paper, an improved dynamic stall model based on the Beddoes-Leishman (B-L) model is proposed for the estimation of nonstationary aerodynamic loads. The B-L model is modified to account for the characteristics of wind turbine aerofoils which operate at lower Mach numbers and have a larger thickness-to-chord ratio compared to aviation aerofoils. Validation of the model is performed extensively through simulations of the S809 aerofoil under pitch oscillation with different mean angles of attack, oscillating amplitudes and reduced frequencies. To understand the effects of the modifications introduced to the dynamic stall model on the aerodynamic fatigue loads over the lifetime of a wind turbine, a load analysis of a 2 MW HAWT is conducted. The load analysis uses the Blade-Element Momentum (BEM) theory in conjunction with the dynamic stall models. The presented modified dynamic stall model is applicable to wind turbine aerofoils with relative thicknesses greater than 15%