Characteristics and triggering mechanisms of early negative Indian Ocean Dipole

Negative Indian Ocean Dipole(nIOD)can exert great impacts on global climate and can also strongly influence the climate in China.Early nIOD is a major type of nIOD,which can induce more pronounced climate anomalies in summer than La Niña-related nIOD.However,the characteristics and triggering mechanisms of early nIOD are unclear.Our results based on reanalysis datasets indicate that the early nIOD and La Niña-related nIOD are the two major types of nIOD,and the former accounts for over one third of all the nIOD events in the past six decades.These two types of nIODs are similar in their intensities,but are different in their spatial patterns and seasonal cycles.The early nIOD,which develops in spring and peaks in summer,is one season earlier than the La Niña-related nIOD.The spatial pattern of the wind anomaly associated with early nIOD exhibits a winter monsoon-like pattern,with strong westerly anomalies in the equatorial Indian Ocean and eastly anomalies in the northern Indian Ocean.Opposite to the triggering mechanism of early positve IOD,the early nIOD is induced by delayed Indian summer monsoon onset.The results of this study are helpful for improving the prediction skill of IOD and its climate impacts.

Triggering mechanism and dynamic process of water-rock flow in Nanfen waste dump in 2010

Water-rock flow is a kind of debris flow with more coarse particles and low viscosity, which occurs in many areas of the world. In this work, the water-rock flow that occurred on May 24, 2010, at Nanfen’s open-pit mine of China was investigated by combining field investigation, meteorological and hydrological survey with numerical simulation to understand its triggering mechanism and dynamic process. The field data shows that the short-term high-intensity rainfall is the most direct inducement to trigger water-rock flow in the waste dump. The loose shallow gravel soil and the V-shaped valley with a certain slope provide the necessary conditions of the occurrence of water-rock flow in the waste dump. Moreover, the possibility criterion of water-rock flow is presented by analyzing the historical rainfall data. In addition, the smoothed particle hydrodynamics(SPH) method was employed to simulate the waterrock flow under the conditions of Newtonian fluid with uniform distribution of water and coarse-grained materials. The simulating results show that the flow distance, velocity, shape, and deposition profile of water-rock flow are in good agreement with the field observation. The present work is beneficial to the risk assessment and mitigation design of water-rock flow disaster in the waste dump.

Study on dynamics of shear waves - Ⅱ Triggering mechanism and amplitude decay

Starting from vorticity equation, the triggering mechanism and amplitude decay of shear waves in the ocean are discussed in this paper. The theoretical analysis indicates that by the action of stripped external force (for examples, the sudden setting of stripped wind, moving stripped wind, etc. ), shear waves can be triggered. This is qualitatively consistent with satellite observations. The amplitude decay process of shear waves by the action of side friction is also discussed in the paper. The theoretical model is quantitatively consistent with satellite observations.

Self-initiated static-dynamic state transition behavior and triggering mechanism of strain rockburst using three-dimensional discrete element method

The accurate understanding of rockburst mechanism poses a global challenge in the field of rock mechanics.Particularly for strain rockburst,achieving self-initiated static-dynamic state transition is a crucial step in the formation of catastrophic events.However,the state transition behavior and its impact on rockburst have not received sufficient attention,and are still poorly understood.Therefore,this study specifically focuses on the state transition behavior,aiming to investigate its abrupt transition process and formation mechanism,and triggering effects on rockburst.To facilitate the study,a novel burst rock-surrounding rock combined laboratory test model is proposed and its effectiveness is validated through experiment verification.Subsequently,corresponding numerical models are established using the three-dimensional(3D)discrete element method(DEM),enabling successful simulation of static brittle failure and rockbursts of varying intensities under quasi-static displacement loading conditions.Moreover,through secondary development,comprehensive recording of the mechanical and energy information pertaining to the combined specimen system and its subsystems is achieved.As a result of numerical investigation studies,the elastic rebound dynamic behavior of the surrounding rock was discovered and identified as the key factor triggering rockburst and controlling its intensity.The impact loading on the burst rock,induced by elastic rebound,directly initiates the dynamic processes of rockburst,serving as the direct cause.Additionally,the transient work and energy convergence towards the burst rock resulting from elastic rebound are recognized as the inherent cause of rockburst.Moreover,it has been observed that a larger extent of surrounding rock leads to a stronger elastic rebound,thereby directly contributing to a more intense rockburst.The findings can provide novel theoretical insights for the exploring of rockburst mechanism and the development of monitoring and prevention techniques.

Mechanisms involved in triggering debris flows,within a cohesive gravel soil mass on a slope:a case in SW China

The triggering mechanisms of debris flows were explored in the field using artificial rainfall experiments in two gullies, Dawazi Gully and Aizi Gully, in Yunnan and Sichuan Provinces, China,respectively. The soils at both sites are bare, loose and cohesive gravel-dominated. The results of a direct shear test, rheological test and back-analysis using soil mass stability calculations indicate that the mechanisms responsible for triggering debris flows involved the decreases in static and dynamic resistance of the soil. The triggering processes can be divided into 7 stages: rainfall infiltration, generation of excess runoff, high pore water pressure, surface erosion, soil creep, soil slipping, debris flow triggering and debris flow increment. In addition, two critical steps are evident:(i) During the process of the soil mass changing from a static to a mobile state, its cohesion decreased sharply(e.g., the cohesion of the soil mass in Dawazi Gully decreased from 0.520 to0.090 k Pa, a decrease of 83%). This would have reduced the soil strength and the kinetic energy during slipping, eventually triggered the debris flow.(ii) When the soil mass began to slip, the velocity and the volume increment of the debris flow fluctuated as a result of the interaction of soil resistance and the sliding force. The displaced soil mass from the source area of the slope resulted in the deposition of a volume of soil more than 7-8 times greater than that in the source area.

Research on the energy consumption mechanism and characteristics of the gallium indium tin liquid metal arcing process

For high-voltage direct current(HVDC)power grid transmission with higher voltages,the energyconsuming branch of the DC circuit breaker is required to dissipate huge energies of more than megajoules in a short time in the case of a fault and short circuit.The requirements for huge volume and weight are difficult to meet with energy-consuming equipment based on ZnO.In this paper,a new energy consumption method is proposed based on gallium indium tin(GaInSn)liquid metal in the arcing process,and a test platform with adjustable short-circuit current is built.The mechanism triggering GaInSn liquid metal arcing energy consumption is studied.It is found that short-circuit current and channel aperture are the key parameters affecting the energy consumption of liquid metal arcing.The characteristics of GaInSn liquid metal energy consumption are investigated,and four stages of liquid metal energy consumption are found:oscillatory shrinkage,arc breakdown,arc burning phase change and arc extinction.The influence of short-circuit current and channel aperture on the energy consumption characteristics of GaInSn liquid metal is investigated.To further explore the physical mechanism of the above phenomena,a magneto-hydrodynamic model of energy consumption in the GaInSn liquid metal arcing process is established.The influence of short-circuit current and channel aperture on the temperature distribution of the liquid metal arc is analyzed.The mechanism of the effect of short-circuit current and channel aperture on peak arc temperature and the temperature diffusion rate is clarified.The research results provide theoretical support for this new liquid metal energy consumption mode DC circuit breaker.

Local Torrential Rainfall Event within a Mei-Yu Season Mesoscale Convective System:Importance of Back-Building Processes

An extreme rainfall event occurred over Hangzhou,China,during the afternoon hours on 24 June 2013.This event occurred under suitable synoptic conditions and the maximum 4-h cumulative rainfall amount was over 150 mm.This rainfall event had two major rainbands.One was caused by a quasi-stationary convective line,and the other by a backbuilding convective line related to the interaction of the outflow boundary from the first rainband and an existing low-level mesoscale convergence line associated with a mei-yu frontal system.The rainfall event lasted 4 h,while the back-building process occurred in 2 h when the extreme rainfall center formed.So far,few studies have examined the back-building processes in the mei-yu season that are caused by the interaction of a mesoscale convergence line and a convective cold pool.The two rainbands are successfully reproduced by the Weather Research and Forecasting(WRF)model with fourlevel,two-way interactive nesting.In the model,new cells repeatedly occur at the west side of older cells,and the backbuilding process occurs in an environment with large CAPE,a low LFC,and plenty of water vapor.Outflows from older cells enhance the low-level convergence that forces new cells.High precipitation efficiency of the back-building training cells leads to accumulated precipitation of over 150 mm.Sensitivity experiments without evaporation of rainwater show that the convective cold pool plays an important role in the organization of the back-building process in the current extreme precipitation case.

Analysis on Triggered Mechanism of a Hail Weather in Tianjin

[ Objective] The research aimed to analyze triggered mechanism of a hail weather in Tianjin on July 10,2011. [Method] Using Micaps data, automatic meteorological observation data, sounding data and Doppler radar data, a hail process rarely happened in Daliutan Village, Yangli- uqing Town, Xiqing District, Tianjin City on July 10, 2011 was analyzed. Triggered mechanism of the hail weather was discussed. [ Result] The hail weather was generated by super cell which was triggered by sea breeze front and ground convergence interaction. Upper situation was in front of the forward tilted trough at bottom rear of the cold vortex, which was favorable for development of the strong convective weather. On ground map, water vapor transportation existed in easterly airflow at bottom rear of the high-pressure. Meanwhile, convergence zone also existed. It was wet lay- er over 0 ℃layer, and strong ascending motion existed, which was favorable for formation and development of the hail. Sea breeze front brought rich moisture, weak cold air and lifting effect when it moved toward inland from ocean, to make up for adverse conditions at low and middle layers. It could trigger a severely convective weather when moved to surface convergence zone. Doppler weather radar could monitor entire hail evolution process, [ Conclusion] The research had obvious guidance significance for judging hail process.

Modeling the multi-level plumbing system of the Changbaishan caldera from geochemical, mineralogical, Sr-Nd isotopic and integrated geophysical data

Changbaishan,an intraplate volcano,is characterized by an approximately 6 km wide summit caldera and last erupted in 1903.Changbaishan experienced a period of unrest between 2002 and 2006.The activity developed in three main stages,including shield volcano(basalts),cone-construction(trachyandesites to trachytes with minor basalts),and caldera-forming stages(trachytes to comendites).This last stage is associated with one of the more energetic eruptions of the last millennium on Earth,the 946 CE,VEI 7 Millennium Eruption(ME),which emitted over 100 km^(3) of pyroclastics.Compared to other active calderas,the plumbing system of Changbaishan and its evolution mechanisms remain poorly constrained.Here,we merge new whole-rock,glass,mineral,isotopic,and geobarometry data with geophysical data and present a model of the plumbing system.The results show that the volcano is characterized by at least three main magma reservoirs at different depths:a basaltic reservoir at the Moho/lower crust depth,an intermediate reservoir at 10-15 km depth,and a shallower reservoir at 0.5-3 km depth.The shallower reservoir was involved in the ME eruption,which was triggered by a fresh trachytic melt entering a shallower reservoir where a comenditic magma was stored.The trachytes and comendites originate from fractional crystallization processes and minor assimilation of upper crust material,while the less evolved melts assimilate lower crust material.Syn-eruptive magma mingling occurred during the ME eruption phase.The magma reservoirs of the caldera-forming stage partly reactivate those of the cone-construction stage.The depth of the magma storage zones is controlled by the layering of the crust.The plumbing system of Changbaishan is vertically extensive,with crystal mush reservoirs renewed by the replenishment of new trachytic to trachyandesitic magma from depth.Unlike other volcanoes,evidence of a basaltic recharge is lacking.The interpretation of the signals preceding possible future eruptions should consider the multi-level nature of the Changbaishan plumbing system.A new arrival of magma may destabilize a part of or the entire system,thus triggering eruptions of different sizes and styles.The reference model proposed here for Changbaishan represents a prerequisite to properly understand periods of unrest to potentially anticipate future volcanic eruptions and to identify the mechanisms controlling the evolution of the crust below volcanoes.

Evidence of earthquakes triggered by the tidal force of the sun and the moon——On the temporal characteristics of the earthquakes in Xingtai,Hejian and Tangshan

Studies by many scientists show that Hebei, China is an area with strong correlation between the tidal force and the occurrences of major earthquakes, the Xingtai earthquake of 1966, the Hejian earthquake of 1967 and the Tangshan earthquake of 1976 were triggered by the tidal force, in this paper the study on the common characteristics of their occurrence times confirms these facts. The computed times of maximum horizontal of the semi diurnal solid tide tidal force show that the occurrence times of the above mentioned earthquakes were close to the times of maximum horizontal tidal force of the semi diurnal solid tide at new moon or full moon. The Longyao earthquake of M =6.8, the Ningjin earthquake of M =7.2 and the Hejian earthquake of M =6.3 occurred tens of minutes after the maximum horizontal tidal force of the semi diurnal solid tides, and the Tangshan earthquake of M =7.8 occurred 16 minutes before the maximum horizontal tidal force. The tidal forces were directed to the west. This is their temporal characteristic. It is generally accepted that the 1969 Bohai earthquake of M =7.4 and the 1975 Haicheng earthquake were not triggered by the tidal force. These events did not show such characteristics. The temporal characteristics of the earthquakes indicate that the occurrences of these events were not random, but were controlled by the tidal force from the sun and the moon, and triggered by the tidal force. These facts agree with the triggering mechanism of the tidal force, are evidences of earthquakes triggered by tidal force.

Mass movements in small canyons in the northeast of Baiyun deepwater area, north of the South China Sea

The process of mass movements and their consequent turbidity currents in large submarine canyons has been widely reported, however, little attention was paid to that in small canyons. In this paper, we document mass movements in small submarine canyons in the northeast of Baiyun deepwater area, north of the South China Sea （SCS）, and their strong effects on the evolution of the canyons based on geophysical data. Submarine canyons in the study area arrange closely below the shelf break zone which was at the depth of -500 m. Within submarine canyons, seabed surface was covered with amounts of failure scars resulted from past small-sized landslides. A complex process of mass transportation in the canyons is indicated by three directions of mass movements. Recent mass movement deposits in the canyons exhibit translucent reflections or parallel reflections which represent the brittle deformation and the plastic deformation, respectively. The area of most landslides in the canyons is less than 3 km2. The trigger mechanisms for mass movements in the study area are gravitational overloading, slope angle and weak properties of soil. Geophysical data indicate that the genesis of submarine canyons is the erosion of mass movements and consequent turbidity currents. The significant effects of mass movements on canyon are incision and sediment transportation at the erosion phases and fillings supply at the fill phases. This research will be helpful for the geological risk assessments and understanding the sediment transportation in the northern margin of the SCS.

Zhang Heng's Seismoscope( 1):Its Emergence

The emergence of Zhang Heng's seismoscope has a profound historical background. This paper intends to explore the formation and material basis of Zhang Heng's scientific thought. It appears that the simple intention of "observing visions and distinguishing good fortune or misfortune"was his motivation to develop the seismoscope. Tracing its historical background,the authors proposed in this paper that the development of this seismoscope started around 128 A. D., and based on perceptual knowledge, two ideas about earthquakes came into being,i. e.,earthquake location could be judged according to the instrument shaking direction, and the earthquake and earth split were essentially different. In the instrument manufacture,Zhang Heng advocated a principle of "making utensils to imitate cosmos". By this principle,the following three problems were readily solved: the seismoscope imitated the response of the suspension system to earthquakes( i. e. natural seismoscope). Technically,the trigger mechanism of the latch was used for reference,and it recorded the physical evidence of earthquake occurrence by an ingenious way of a ball dropping from a dragon's mouth. The solution of these three key problems lead to the emergence of the seismoscope in 132 A. D. and the successful detection of an earthquake in 134 A. D. His invention deepened humanity's knowledge of natural laws, and promoted the development of science and technology in that time and later.

Late onsets of tropical cyclones in the decaying years of super El Niño events

The 2015/2016 El Nino event reached the threshold of super El Nino event,and was comparable to the super events in 1982/1983 and 1997/1998.Interestingly,the tropical cyclones(TCs)were found to have very late onsets in the decaying years of the super El Nino events.This study discusses the causes of late TC onsets related with atmospheric circulation,disturbance sources and trigger mechanisms.The analysis shows that the western North Pacific subtropical high(WNPSH)from January–June during the decaying years of the super El Nino events were stronger than the climatic mean,which resulted in a relatively stable atmospheric state by inhibiting deep convection.As a disturbance source,the April–June intertropical convergence zone(ITCZ)during the decaying years of the super El Nino events were significantly weaker than its climatic mean.The cross-equatorial flow and monsoon trough,as important TC generation triggers,were weaker from April–June during the decaying years of the super El Nino events,which further reduced the probability of TC generation.As for the late TC onsets,the role of atmospheric circulation anomalies(i.e.,subtropical-high,the ITCZ,cross-equatorial flow,and monsoon trough)were more important.The cross-equatorial flow may take as predictor of TC onsets in the decaying years of the super El Nino events.

A Case Study on the Triggering of Thermal Convective Precipitation

Thermal convective precipitation （TCP） often occurs over China's Mainland in summer when the area is dominated by the western Pacific subtropical high （WPSH）. It is well known that the WPSH often brings about large scale subsidence, then why could deep moist convection occur and where does the water vapor come from？ In this paper, a deep convective precipitation case that happened on 2 August 2003 is studied in order to address these two questions. First, the characteristics of the TCP event are analyzed using the Tropical Rainfall Measuring Mission （TRMM） satellite data, automatic weather station observations, and the data from the US National Centers for Environmental Prediction （NCEP）. Second, water vapor sources are identified through examining surface evaporation, water vapor advection, and water vapor flux divergence calculated by using a regionally averaged water vapor budget equation. Furthermore, using an Advanced Regional Eta-coordinate Model （AREM）, contributions of sensible and latent heat fluxes to the TCP are compared through four sensitivity experiments. The results show that in the regions controlled by the WPSH, surface temperature rises rapidly after sunrise. Upon receiving enough sensible heat, the air goes up and leads to convergence in the lower atmosphere. Then the water vapor assembled from the surroundings and the ground surface is transported to the upper levels, and a favorable environment for the TCP forms. A model data diagnosis indicates that about half of precipitable water comes from the convergence of horizontal fluxes of water vapor, and the other half from surface evaporation, while little is from advection. Additional sensitivity experiments prove that both sensible and latent heating are essential for the onset of the TCP. The sensible heat flux triggers thermodynamic ascending motion, and the latent heat flux provides water vapor, but the contribution to TCP from the latter is a little smaller than that from the former.

The landslide problem

The synonymous use of the general term ＂landslide＂, with a built-in reference to a sliding motion, for all varieties of mass-transport deposits （MTD）, which include slides, slumps, debrites, topples, creeps, debris avalanches etc. in subaerial, sublacustrine, sub- marine, and extraterrestrial environments has created a multitude of conceptual and nomen- clatural problems. In addition, concepts of triggers and Iong-runout mechanisms of mass movements are loosely applied without rigor. These problems have enormous implications for studies in process sedimentology, sequence stratigraphy, palaeogeography, petroleum geol- ogy, and engineering geology. Therefore, the objective of this critical review is to identify key problems and to provide conceptual clarity and possible solutions. Specific issues are the fol- lowing： （1） According to ＂limit equilibrium analyses＂ in soil mechanics, sediment failure with a sliding motion is initiated over a shear surface when the factor of safety for slope stability （F） is less than 1. However, the term landslide is not meaningful for debris flows with a flowing mo- tion. （2） Sliding motion can be measured in oriented core and outcrop, but such measurement is not practical on seismic profiles or radar images. （3） Although 79 MTD types exist in the geological and engineering literature, only slides, slumps, and debrites are viable depositional facies for interpreting ancient stratigraphic records. （4） The use of the term landslide for high- velocity debris avalanches is inappropriate because velocities of mass-transport processes cannot be determined in the rock record. （5） Of the 21 potential triggering mechanisms of sediment failures, frequent short-term events that last for only a few minutes to several hours or days （e.g., earthquakes, meteorite impacts, tsunamis, tropical cyclones, etc.） are more relevant in controlling deposition of deep-water sands than sporadic long-term events that last for thousands to millions of years （e.g., sea-level Iowstands）. （6） The comparison of HIL （fall height/runout distance） ratios of MTD in subaerial environments with H/L ratios of MTD in submarine and extraterrestrial environments is incongruous because of differences in data sources （e.g., outcrop vs. seismic or radar images）. （7） Slides represent the pre-transport dis- position of strata and their reservoir quality （i.e., porosity and permeability） of the provenance region, whereas debrites reflect post-transport depositional texture and reservoir quality. How- ever, both sandy slides and sandy debrites could generate blocky wireline （gamma-ray） log motifs. Therefore, reservoir characterization of deep-water strata must be based on direct examination of the rocks and related process-specific facies interpretations, not on wireline logs or on seismic profiles and related process-vague facies interpretations. A solution to these problems is to apply the term ＂landslide＂ solely to cases in which a sliding motion can be em- pirically determined. Otherwise, a general term MTD is appropriate. This decree is not just a quibble over semantics; it is a matter of portraying the physics of mass movements accurately. A precise interpretation of a depositional facies （e.g., sandy slide vs. sandy debrite） is vital notonly for maintaining conceptual clarity but also for characterizing petroleum reservoirs.

Role of a Meso-γ Vortex in Meiyu Torrential Rainfall over the Hangzhou Bay,China:An Observational Study

A mesoscale torrential rainfall event that occurred over eastern China in June 2013 is analyzed by using observational data.The results show that a mesoscale convergence line and a weak convective cloud line formed over the northern part of the Hangzhou Bay during the onset of the torrential rainfall event.A meso-vortex appeared over the confluence point of northeasterly flow associated with the Yellow-Sea high,easterly flow from rainfall area,and southeasterly flow from the Hangzhou Bay.The meso-vortex with a horizontal scale of 10-20 km lasted for about 1 h for stable surface circulations.The analysis of radar retrieval reveals that the meso-vortex in the boundary layer occurred at the south of strong radar echo.The formation of the meso-vortex turned to enhance convergence and cyclonic vorticity in the lower troposphere,which strengthened updrafts that are tilted into convective clouds and caused torrential rainfall.Thus,the occurrence of the meso-vortex in boundary layer is one of the mechanisms that are responsible for the enhancement of convective development.

Mass-independent fractionation of even mercury isotopes

Practically all physical, chemical, and biologi- cal processes can induce mass-dependent fractionation of mercury （Hg） isotopes. A few special processes such as photochemical reduction of Hg（Ⅱ） and photochemical degradation of methylmercury （MeHg） can produce mass- independent fractionation （MIF） of odd Hg isotopes （odd- MIF）, which had been largely reported in variable natural samples and laboratory experiments, and was thought to be caused by either nuclear volume effect or magnetic isotope effect. Recently, intriguing MIF of even Hg isotopes （even- MIF） had been determined in natural samples mainly related to the atmosphere. Though photo-oxidation in the tropopause （inter-layer between the stratosphere and the troposphere） and neutron capture in space were thought to be the possible processes causing even-MIF, the exact mechanism triggering significant even Hg isotope anomaly is still unclear. Even-MIF could provide useful information about the atmospheric chemistry and related climate changes, and the biogeochemical cycle of Hg.

Side-Channel Attacks in a Real Scenario

Existing Side-Channel Attacks （SCAs） have several limitations and, rather than to be real attack methods, can only be considered to be security evaluation methods. Their limitations are mainly related to the sampling conditions, such as the trigger signal embedded in the source code of the encryption device, and the acquisition device that serves as the encryption-device controller. Apart from it being very difficult for an attacker to add a trigger into the original design before making an attack or to control the encryption device, there is a big gap in the capacity of existing SCAs to pose real threats to cipher devices. In this paper, we propose a new method, the sliding window SCA （SW-SCA）, which can be applied in scenarios in which the acquisition device is independent of the encryption device and for which the encryption source code requires no trigger signal or modification. First, we describe the main issues in existing SCAs, then we theoretically analyze the effectiveness and complexity of our proposed SW-SCA --a method that can incorporate a sliding-window mechanism into almost all of the existing non-profiled SCAs. The experimental results for both simulated and physical traces verify the effectiveness of the SW-SCA and the appropriateness of its theoretical complexity.