A Review of Research on Catastrophic Formation and Evolutionary Mechanism of Deep High Stress Rock Mass under Impact Loading

With the exploitation of resources expanded to deep, the geological environment which is “three tenors one disturbance” of rock mass in great depth has been more complex, resulting in some new engineering geological disasters, such as rock burst, pressure bumping, large deformation of surrounding rock, brittle-ductile transition of rock and zonal disintegration of rock mass, which occur frequently in deep underground engineering rock mass. The impact load caused by collision, explosion, extrusion and outburst is the root cause of the dynamic instability of the deep rock mass. What should be emphasized is that high in-situ stress and blasting excavation disturbance complicate disaster developing mechanism of deep underground engineering rock mass and sharply increase the difficulty of controlling disaster. This paper is aimed at the research status and development trend, of which dynamic characteristics of deep high stress rock mass and its damage and failure effect each other under impact, and conduct analysis, in the later stage where I would discuss how to carry out the response law of the deep high-stress rock mass under the impact load and the mechanism of catastrophe developing, which is of great significance to build a model of instability and fracture evolution about deep rock mass under shock disturbance and to maintain its safety and stability.

In situ optical backpropagation training of diffractive optical neural networks:publisher’s note

This publisher’s note corrects the authors’affiliations in Photon.Res.8,940(2020).

In-situ TEM observation of the evolution of helium bubbles & dislocation loops and their interaction in Pd during He^(+) irradiation

The microstructural evolution of purity Pd under 30 keV He^(+)irradiation at 573 K was investigated by in-situ transmission electron microscopy.The nucleation,growth,merging,annihilation,size change,number density variation,and types of dislocation loops were analyzed under the influence of irradiation fluence and sample thickness.Both perfect dislocation loops with b=1/2<110>and faulted dislocation loops with b=1/3<111>were formed.However,at low irradiation fluence,most of the loops were 1/3<111>loops.The thickness of TEM foil obviously affected the ratio of 1/3<111>loop variants,the size and number density of dislocation loops,and the characteristics of bubble-loop complexes.With the increase of irradiation fluence,the size of dislocation loops increased,but loop volume number density remained almost constant until dislocation loops merged and evolved into dislocation network.There was an obvious interaction between dislocation loops and bubbles,indicating that 1/3<111>loop was first formed at the initial stage of irradiation,and when the loop grew to a certain size,obvious helium bubbles appeared inside its region.

Atmospheric Pressure-Aware Seamless 3-D Localization and Navigation for Mobile Internet Devices

This paper describes a seamless three-dimensional （3-D） localization and navigation system for smartphones. The smartphone includes an atmospheric pressure sensor to measure the user＇s altitude that is combined with the outdoor Global Positioning System （GPS） and indoor WiFi-APs localization systems in a seamless 3-D localization system. The smartphone software also provides seamless navigation services by updating map information for both indoor and outdoor locations through the mobile Internet. The indoor floor information calculated from the altitude information is used to project localization anchor nodes, e.g., WiFi-AP, on different floors onto the user＇s floor with an indoor 3-D localization algorithm using projection distances based on a Received Signal Strength （RSS） algorithm. Tests show that the 3-D method reduces systematic errors and achieves much higher accuracy than the traditional two-dimensional localization method.

Effect of dose rate on the characteristics of dislocation loops in palladium:In-situ TEM analysis during 30 keV H_(2)^(+)irradiation

Ion irradiation is usually used to simulate neutron irradiation to accelerate the evaluation of the irradia-tion behavior of reactor materials.However,the validity of using a high damage rate of ion irradiation to simulate a low damage rate of neutron irradiation has always been a controversial topic.Here,the effect of two dose rates(2.94×10^(-6) and 7.35×10^(-5) dpa s^(-1))on the characteristics and evolution of dislo-cation loops in palladium was studied in situ during 30 keV H2+irradiation using transmission electron microscopy.The dose rate obviously affected the nucleation rate and growth rate of dislocation loops,the types(Frank loops or perfect loops)of dislocation loops,and the irradiation hardening and total damage obtained from the product of average loop size and loop density.At the same irradiation dose,a high dose rate would lead to high loop density,small average loop size,low loop growth rate,and low irra-diation hardening and damage induced by loops in pure Pd.Meanwhile,it was found for the first time that a high dose rate was beneficial to the generation of perfect dislocation loops.The effect of dose rate was attributed to the different dynamic equilibrium results between the effective generation rate of point defects and their absorption rate by existing sinks.The present results show that the effect of dose rate should be considered when using ion irradiation to simulate neutron irradiation to evaluate the irradiation damage to materials.

ARTC1-mediated VAPB ADP-ribosylation regulates calcium homeostasis

Mono-ADP-ribosylation(MARylation)is a post-translational modification that regulates a variety of biological processes,including DNA damage repair,cell proliferation,metabolism,and stress and immune responses.In mammals,MARylation is mainly catalyzed by ADP-ribosyltransferases(ARTs),which consist of two groups:ART cholera toxin-like(ARTCs)and ART diphtheria toxin-like(ARTDs,also known as PARPs).The human ARTC(hARTC)family is composed of four members:two active mono-ADP-ARTs(hARTC1 and hARTC5)and two enzymatically inactive enzymes(hARTC3 and hARTC4).In this study,we systematically examined the homology,expression,and localization pattern of the hARTC family,with a particular focus on hARTC1.Our results showed that hARTC3 interacted with hARTC1 and promoted the enzymatic activity of hARTC1 by stabilizing hARTC1.We also identified vesicle-associated membrane protein-associated protein B(VAPB)as a new target of hARTC1 and pinpointed Arg50 of VAPB as the ADP-ribosylation site.Furthermore,we demonstrated that knockdown of hARTC1 impaired intracellular calcium homeostasis,highlighting the functional importance of hARTC1-mediated VAPB Arg50 ADP-ribosylation in regulating calcium homeostasis.In summary,our study identified a new target of hARTC1 in the endoplasmic reticulum and suggested that ARTC1 plays a role in regulating calcium signaling.

In situ optical backpropagation training of diffractive optical neural networks

Training an artificial neural network with backpropagation algorithms to perform advanced machine learning tasks requires an extensive computational process.This paper proposes to implement the backpropagation algorithm optically for in situ training of both linear and nonlinear diffractive optical neural networlks,which enables the acceleration of training speed and improvement in energy efficiency on core computing modules.We demonstrate that the gradient of a loss function with respect to the weights of diffractive layers can be accurately calculated by measuring the forward and backward propagated optical fields based on light reciprocity and phase conjunction principles.The diffractive modulation weights are updated by programming a high-speed spatial light modulator to minimize the error between prediction and target output and perform inference tasks at the speed of light.We numerically validate the effectiveness of our approach on simulated networks for various applications.The proposed in situ optical learning architecture achieves accuracy comparable to in silico training with an electronic computer on the tasks of object dlassification and matrix-vector multiplication,which further allows the diffractive optical neural network to adapt to system imperfections.Also,the self-adaptive property of our approach facilitates the novel application of the network for all-optical imaging through scattering media.The proposed approach paves the way for robust implementation of large-scale difractive neural networks to perform distinctive tasks all-optically.

The effect of Laves phase on heavy-ion radiation response of Nb-containing FeCrAl alloy for accident-tolerant fuel cladding

As a promising candidate material for the accident tolerant fuel cladding in light water reactors,the Nb-containing FeCrAl alloy has shown outstanding out-of-pile service performance due to the Laves phase precipitation.In this work,the radiation response in FeCrAl alloys with gradient Nb content under heavy ion radiation has been investigated.The focus is on the effect of the Laves phase on irradiation-induced defects and hardening.We found that the phase boundary between the matrix and Laves phase can play a critical role in capturing radiation defects,as verified by in-situ heavy-ion radiation experiments and molecular dynamic simulations.Additionally,the evolution of Laves phase under radiation is analyzed.Radiation-induced amorphization and segregations observed at high radiation doses will deepen the fundamental understanding of the stability of Laves phases in the radiation environment.

In-situ TEM study on the evolution of dislocation loops and bubbles in CeO_(2)during Kr^(+)single-beam and Kr^(+)-H_(2)^(+)dual-beam synergetic irradiation

CeO_(2)is widely used as the nonradioactive surrogate fuel of UO_(2)when studying the irradiation performance of UO_(2).The evolution and characteristics of dislocation loops and bubbles in CeO_(2)foils were studied by in-situ transmission electron microscopy(TEM)observation during 400 ke V Kr^(+)&30 ke V H_(2)^(+)dual-beam synergetic irradiation and 400 ke V Kr^(+)single-beam irradiation at 1073 K.The rotation of the habit plane of dislocation loops induced by above ion irradiation was found in the CeO_(2)for the first time,such as from[211]to[311]and then to[100].The rafted loops were first observed under Kr^(+)&H_(2)^(+)dual-beam synergetic irradiation,which not only had similar[111]direction,but also belonged to perfect dislocation loops(PDLs).The rafted loops were formed not only by the growth of loops that absorbed irradiation defects,but also by the combination of loops.But,this phenomenon of loop rafting was not obvious during Kr single-beam irradiation.It was first found that Kr^(+)irradiation induced the change of Burgers vectors of PDLs.The absorption of large PDLs to small PDLs was also observed.The average size and areal number density of dislocation loops and gas bubbles as a function of irradiation dose were constructed,which showed that the addition of H_(2)^(+)obviously affected the characteristics of dislocation loops and gas bubbles and the swelling of CeO_(2).

In-situ TEM investigation of dislocation loop reaction and irradiation hardening in H_(2)^(+)-He^(+) dual-beam irradiated Mo

Through in-situ TEM observation during 30 keV H_(2)^(+)-He^(+) dual-beam irradiation at 723 K,the reaction and transformation of dislocation loops in pure Mo were investigated,especially for<100>loops.Irradiation could directly cause the formation of 1/2<111>loops and<100>loops,but 1/2<111>loops were dominant.In-situ observation confirmed the formation mechanism of<100>loops,including direct irradiation induced mechanism,1/2<111>loop direct conversion mechanism,and reaction mechanism of two 1/2<111>loops.Meanwhile,the reaction of two 1/2<111>loops to produce<100>loop should not require the strict size similarity condition.The reaction between 1/2<111>loops could also produce 1/2<111>loop,which was essentially a process in which one loop absorbed another one.The yield strength increment caused by irradiation-induced loops was analyzed,and its saturation value reached0.48 GPa at 0.06 dpa.Compared with single He+irradiation,the number density and average diameter of loops increased significantly and more serious damage was caused under the synergistic effect of hydrogen and helium.The mechanism based on in-situ experimental observation was discussed in depth.

Joint view synthesis and disparity refinement for stereo matching

Typical stereo algorithms treat disparity estimation and view synthesis as two sequential procedures.In this paper,we consider stereo matching and view synthesis as two complementary components,and present a novel iterative refinement model for joint view synthesis and disparity refinement.To achieve the mutual promotion between view synthesis and disparity refinement,we apply two key strategies,disparity maps fusion and disparity-assisted plane sweep-based rendering(DAPSR).On the one hand,the disparity maps fusion strategy is applied to generate disparity map from synthesized view and input views.This strategy is able to detect and counteract disparity errors caused by potential artifacts from synthesized view.On the other hand,the DAPSR is used for view synthesis and updating,and is able to weaken the interpolation errors caused by outliers in the disparity maps.Experiments on Middlebury benchmarks demonstrate that by introducing the synthesized view,disparity errors due to large occluded region and large baseline are eliminated effectively and the synthesis quality is greatly improved.