Self-consistent Constitutive Modeling of the Creep Damage Behaviour of Nickel-base Directionally Solidified Superalloys with Different Grain Orientations

A self consistent creep damage constitutive model is developed for nickel-base directionally solidified superalloys. Grain degradation and grain boundary voiding are considered. The model parameters are determined from the creep test data of single crystal and directionally solidified superalloy with a special grain orientation. The numerical analysis shows that the model creep damage behaviours of nickel-base directionally solidified superalloys with difFerent grain orientations are in good agreement with the experimental data.

Adaptive Fuzzy Logic Despeckling in Non-Subsampled Contourlet Transformed Ultrasound Pictures

Signal to noise ratio in ultrasound medical images captured through the digital camera is poorer,resulting in an inaccurate diagnosis.As a result,it needs an efficient despeckling method for ultrasound images in clinical practice and tel-emedicine.This article proposes a novel adaptive fuzzyfilter based on the direc-tionality and translation invariant property of the Non-Sub sampled Contour-let Transform(NSCT).Since speckle-noise causes fuzziness in ultrasound images,fuzzy logic may be a straightforward technique to derive the output from the noisy images.Thisfiltering method comprises detection andfiltering stages.First,image regions classify at the detection stage by applying fuzzy inference to the directional difference obtained from the NSCT noisy image.Then,the system adaptively selects the better-suitedfilter for the specific image region,resulting in significant speckle noise suppression and retention of detailed features.The suggested approach uses a weighted averagefilter to distinguish between noise and edges at thefiltering stage.In addition,we apply a structural similarity mea-sure as a tuning parameter depending on the kind of noise in the ultrasound pic-tures.The proposed methodology shows that the proposed fuzzy adaptivefilter effectively suppresses speckle noise while preserving edges and image detailed structures compared to existing approaches.

Effect of Wave Headings on the Dynamic Response of the Continuous Mating Operation of Floatover Installation

The topside floatover installation is always a great challenge and is sensitive to environmental conditions.In this study,experimental analysis on the mating operation of the floatover installation in different wave headings is presented.The continuous mating operation using the rapid transfer technique was experimentally simulated with the assistance of the jacking system and the ballast system.In the continuous transfer modeling,the topsides loads were transferred onto the jacket by several consecutive steps,including the first rapid jack-down for the 30%loads,continuous 30%−70%load transfer and the second repaid jack-down for the remaining 30%loads.Motions of the barge and the topsides as well as loads on the Deck Support Unite(DSU)and the Leg Mating Unite(LMU)in different wave headings were measured.Experimental results illustrated the complex motion behavior and load characteristics of the continuous transfer operation.Results indicate that the rapid jack-down operations will lead to impact loads and larger lateral DSU loads.The bow quartering seas are much more dangerous as it gives rise to the larger motions and loads.Comparisons with the traditional steady-state modeling indicate that the continuous transfer modeling has greater advantages over the steady-state modeling on predicting the loads.

Removing Random-Valued Impulse Noises by a Two-Staged Nonlinear Filtering Method

Digital images are frequently contaminated by impulse noise(IN)during acquisition and transmission.The removal of this noise from images is essential for their further processing.In this paper,a two-staged nonlinear filtering algorithm is proposed for removing random-valued impulse noise(RVIN)from digital images.Noisy pixels are identified and corrected in two cascaded stages.The statistics of two subsets of nearest neighbors are employed as the criterion for detecting noisy pixels in the first stage,while directional differences are adopted as the detector criterion in the second stage.The respective adaptive median values are taken as the replacement values for noisy pixels in each stage.The performance of the proposed method was compared with that of several existing methods.The experimental results show that the performance of the suggested algorithm is superior to those of the compared methods in terms of noise removal,edge preservation,and processing time.

Amplitude variation characteristics of active source airgun signals at Qilian Mountain

In this study,Qilian Mountain active source airgun signals recorded at 79 stations were obtained after stacking waveforms from July 2015 to December 2016.Based on analysis of the amplitude variation characteristics of the airgun signals,the following conclusions were drawn:along the NW-SE fault distribution direction of the Qilian Mountain area,the decrease in amplitude of airgun signals was relatively slow in relation to the epicentral distance,while the decrease in amplitude in the direction perpendicular to the fault was relatively fast.This difference may be related to the energy loss of seismic waves reflecting and scattering by the regional faults mainly distributed along the NW-SE direction,which are caused by tectonic compression of the QinghaiTibet and Alxa blocks.

Between“Guandai”(冠带)and“Yidi”(夷狄):Sima Qian's National Consciousness

During the reign of Emperor Wu of Han Dynasty,the ethnic relations in China entered a new historical stage.Records of the Historian written during this period gives a basically factual account of the ethnic history in China since ancient epochs.It is the first specialized work on ethnic history.The national consciousness that Sima Qian presents in this work is distinctively different from the Confucian tradition,which draws a strict line between Hua(华,China)and Yi(夷,the barbarians).His attention on the commonality of the cultural genes between the farming peoples of the Central-Plains and the nomadic hunting peoples of the borderlands,his recognition of the integrated impact that multiple ethnic groups have on the rise and development of Huaxia(华夏,Chinese)civilization,his respect for"differences among barbarians of the four directions"(四夷各异),and his approval of the“merits of Hu attire”(胡服之功)are all embodiment of his liberal views.To explore the formation and development of the cultural community of the Chinese nation and to understand and interpret this historical process of ethnic integration,we should attach great importance to the positive significance of Sima Qian's national consciousness.