Energy Accumulation Research Articles

Transcriptome analysis unveiled the genetic basis of rapid seed germination strategies in alpine plant Rheum pumilum

Rheum pumilum stands as both a quintessential alpine plant and a significant traditional Chinese and Tibetan medicinal herb. Unraveling the molecular intricacies of seed germination in Rh. pumilum not only unveils the genetic foundations of plant seed germination strategies in high-altitude environments but also offers insights for cultivating Rh. pumilum medicinal materials. Employing transcriptome sequencing and the Weighted Gene Co-expression Network Analysis, this study delved into the shifts in gene expression levels across various stages of seed germination in Rh. pumilum. The process of seed germination in Rh. pumilum entails a cascade of complex physiological events. Six hormones (ABA, IAA, ETH, GA, BR, CK) emerged as pivotal players in seeds breaking in shells and the facilitation of rapid seed germination in Rh. pumilum. Fourteen transcription factor families (LOB, GRAS, B3, bHLH, bZIP, EIL, MYB, MYB related, NAC, TCP, WRKY, HSF, PLATZ, and SBP) along with four key genes (E2.4.1.13, EIN3, BZR, and BIN2) were identified that may be associated with both biotic and abiotic environmental stress. The ETR, ACACA and ATPeV0C genes were linked with energy accumulation during the initial stages of seed germination, CYP707A may play an important role in breaking seed dormancy, while the BRI1 gene may be correlated with swift seed germination. Additionally, several unidentified genes were recognized to play key roles in seed germination of Rh. pumilum, warranting further investigation. Moreover, Rh. pumilum demonstrates full activation of crucial physiological functions such as energy metabolism, signal transduction, and responses to biological and abiotic stresses during the seed breaking in shells. This study provides molecular evidence elucidating the swift seed germination strategies adopted by alpine plants to thrive in high-altitude environments. Furthermore, it serves as a foundational reference for enhancing seed germination rates and breeding practices to promote the sustainable development of Rh. pumilum medicinal materials.

Volumetric and energy production assessment of wood in managed forest in the Brazilian arid biome

There is a growing demand for wood products from forests located in dry regions, which includes the Caatinga, a biome in Northeast Brazil. This study evaluates the relationship between volumetric production, energy potential, and the rotation cycle. Information was collected from forest stands in different stages of regeneration located in an arid region of Brazil. Based on the forest management plan, four fields were selected with post-logging ages of 9, 11, 13, and 16 years. This inventory recorded circumference at chest height, circumference at base height, total height, volume, stored energy, technical cutting age, and rainfall index. The results showed that the species that presented the most significant quantity of stems did not always correspond to those that obtained the most significant amount of biomass. The technical cutting age was determined at 16 years, aiming to maximize wood utilization. Regarding energy density, the 9-year-old field reached 7,281 kcal ha-1, the 11-year-old field obtained 14,448 kcal ha-1, the 13-year-old field recorded 41,526 kcal ha-1, and the 16-year-old field reached 98,190 kcal ha-1. The species that contributed most to energy accumulation included Mimosa tenuiflora with 3,740 kcal m–³, Piptadenia stipulacea with 3,271 kcal m-3, and Cenostigma pyramidale with 3,101 kcal m-3.

Design and molecular dynamics of biocompatible WPU/PVA composite hydrogels with enhanced fatigue resistance: Energy dissipation of intermolecular clusters for elastomers

To engineer a hydrogel elastomer for use as an in vivo tissue replacement, it is imperative to ensure superior fatigue resistance, guaranteeing a prolonged service life. Investigating the molecular mechanisms of strain energy accumulation and transmission, which occur during the compression of elastomeric materials, is instrumental in elucidating the causes of hydrogel material fatigue. Such insights are of immense value for the development of durable artificial tissue replacements, ensuring their longevity and sustained functionality within the human body. We synthesized hydrogel elastomers through polyvinyl alcohol (PVA) and waterborne polyurethane (WPU) with good biocompatibility, and studied their fatigue behavior through molecular dynamics (MD). The results of this analysis demonstrate that the introduction of energy dissipation structures between mechanically supported molecular frameworks can enhance the relaxation efficiency of polymers. This improvement leads to enhanced resistance of hydrogels to compression fatigue. A total of 1,000,000 cycles of compression tests were conducted to verify that WPU/PVA did not exhibit any significant compression fatigue under high stress of 50 % strain. In contrast, PVA hydrogel exhibited obvious fatigue due to the absence of an energy dissipation structure. These results revealed the source of compression fatigue resistance of hydrogel elasticity and provided powerful guidance for the design and synthesis of artificial tissues.

Mechanism and Prevention of Rock Burst in a Wide Coal Pillar under the Superposition of Dynamic and Static Loads

To address the frequent occurrence of rock burst disasters in areas with wide coal pillars during mining in the western mining area of China, the wide coal pillar area of the Tingnan coal mine in Shanxi Province was used as the research background. Theoretical analysis, numerical simulation, and field tests were used to establish the mechanical criterion and the energy criterion for the dynamic instability of wide coal pillars. The process and mechanism of wide coal pillar dynamic instability under dynamic and static load disturbances were revealed, and a wide coal pillar rock burst prevention and control scheme was proposed. The results indicated that when the load above a coal pillar reached the stress failure index and the energy failure index was met, the coal pillar reached the critical conditions for rock burst. With increasing static load, the stress, energy, and range of the plastic zone all showed increasing trends on both sides of the coal pillar. Under a given dynamic load, the stress and plastic zone range of the coal pillar significantly increased compared to those without a dynamic load. Under a given static load, the greater the dynamic load, the more likely the coal pillar was to undergo dynamic instability. The evolution of coal pillar dynamic instability was divided into three stages: energy accumulation, local instability, and dynamic instability. When the critical stress and energy conditions for coal pillar dynamic instability are exceeded, rock burst will occur. To reduce the static and dynamic loads of coal pillars, a rock burst prevention and control scheme of energy release and load reduction was proposed and applied onsite. The monitoring results showed that this control plan effectively reduced the stress of the coal pillar and the dynamic load generated by the fracture of the overlying rock layer, indicating safe mining in this area of wide coal pillars.

Disturbance-immune, fast response LITES gas sensor based on out-plane vibration mode employing micro Fabry-Perot cavity with heterodyne phase demodulation

The disturbance-immune, fast response light-induced thermoelastic spectroscopy (LITES) gas sensor based on out-plane vibration (OPV) mode employing micro Fabry-Perot cavity with heterodyne phase demodulation was firstly reported in this paper. Compared to the traditional in-plane vibration (IPV) mode, the OPV mode has a lower resonance frequency (f0) to enhance the energy accumulation time of the system. The OPV mode based H-LITES (OPV-H-LITES) sensor and the IPV mode based H-LITES (IPV-H-LITES) sensor were established using a standard quartz tuning fork (QTF) at the same conditions for performance comparison. Acetylene (C2H2) was selected as the target gas to verify the sensor performance. In comparison to the IPV-H-LITES sensor, there has been a 3.5-fold improvement in signal-to-noise ratio (SNR) of OPV-H-LITES sensor. In order to further improve the sensor performance, a novel self-designed low-frequency QTF was adopted to replace the standard QTF, leading to a 2.3-fold increase in the SNR of the OPV-H-LITES sensor. Finally, a minimum detection limit (MDL) of 7.22 ppm for C2H2 detection was obtained. The proposed technique holds the merits of high sensitivity, power disturbance resistance, wavelength independence, excellent linear concentration response and long-term stability.

The influence of length under blast load on the propagation mechanism of interconnected cracks

In order to study the influence of interconnected defects on the rock breaking effect under blast load, the relevant explosion experiment was carried out by prefabricating interconnected cracks on plexiglass plates (PMMA), and the propagation mechanism of interconnected cracks under blast load was studied from the length level. The dynamic caustic line system and finite element analysis software were combined to analyze the stress intensity factor, propagation velocity of the interconnected crack tip, and full-field stress of the specimen; the results show that with the radial stress wave propagation direction as the axis of symmetry, the two interconnected cracks with symmetrical angles but different lengths are under the action of blast load; there is a certain competition between the two cracks; the longer cracks are more likely to initiate and propagate, and the shorter cracks almost do not propagate. In addition, in terms of energy accumulation at the tips of the two cracks, the longer crack has a certain inhibitory effect on the shorter crack, and when the length of the longer crack remains unchanged, the inhibition effect weakens with the increase of the length of the shorter crack, and when the length of the shorter crack remains unchanged, the inhibitory effect increases with the increase of the length of the longer crack. After the crack initiation of the longer crack, the relationship curve between the stress intensity factor and the crack propagation velocity and time of the longer crack tip decreases first, and then the relationship curve rises to the peak as the energy of the tip of the shorter crack is transferred to the longer crack, and then the oscillation decreases, while the stress intensity factor and crack propagation rate of the shorter side crack tip show an overall downward trend. The numerical simulation is used to supplement the analysis of the stress propagation in the full-field of the specimen, which corroborates with the experiment results. The experimental study provides a theoretical basis for the analysis of the propagation mechanism of interpenetrating cracks under blast load in practical engineering.

Assessment and control of the mine tremor disaster induced by the energy accumulation and dispersion of thick-hard roofs

In order to solve the problem that current theory models cannot accurately describe thick-hard roof (THR) elastic energy and assess the mine tremor disasters, a theoretical method, a Timoshenko beam theory on Winkler foundation was adopted to establish the THR’s periodic breaking model. The superposition principle was used for this complex model to derive the calculation formulas of the elastic energy and impact load on hydraulic supports. Then, the influence of roof thickness h, cantilever length L1, and load q on THR’s elastic energy and impact load was analyzed. And, the effect of mine tremor disasters was assessed. Finally, it is revealed that: (1) The THR’s elastic energy U exhibits power-law variations, with the fitted relationships U=0.0096L13.5866, U=5943.9h−1.935, and U=21.049q2. (2) The impact load on hydraulic supports FZJ increases linearly with an increase in the cantilever length, thickness, and applied load. The fitted relationships are FZJ=1067.3L1+6361.1, FZJ=125.89h+15100, and FZJ=10420q+3912.6. (3) Ground hydraulic fracturing and liquid explosive deep-hole blasting techniques effectively reduce the THR’s cantilever length at periodic breakages, thus eliminating mine tremor disasters.

Uncovering Nanoindention Behavior of Amorphous/Crystalline High-Entropy-Alloy Composites.

Amorphous/crystalline high-entropy-alloy (HEA) composites show great promise as structural materials due to their exceptional mechanical properties. However, there is still a lack of understanding of the dynamic nanoindentation response of HEA composites at the atomic scale. Here, the mechanical behavior of amorphous/crystalline HEA composites under nanoindentation is investigated through a large-scale molecular dynamics simulation and a dislocation-based strength model, in terms of the indentation force, microstructural evolution, stress distribution, shear strain distribution, and surface topography. The results show that the uneven distribution of elements within the crystal leads to a strong heterogeneity of the surface tension during elastic deformation. The severe mismatch of the amorphous/crystalline interface combined with the rapid accumulation of elastic deformation energy causes a significant number of dislocation-based plastic deformation behaviors. The presence of surrounding dislocations inhibits the free slip of dislocations below the indenter, while the amorphous layer prevents the movement or disappearance of dislocations towards the substrate. A thin amorphous layer leads to great indentation force, and causes inconsistent stacking and movement patterns of surface atoms, resulting in local bulges and depressions at the macroscopic level. The increasing thickness of the amorphous layer hinders the extension of shear bands towards the lower part of the substrate. These findings shed light on the mechanical properties of amorphous/crystalline HEA composites and offer insights for the design of high-performance materials.

Reservation of the heat supply system with biofuel heat energy sources

The implementation of the reservation of the heat supply system to a populated area was analyzed. It is noted that increasing the reliability of heat supply to consumers is a fundamental task, especially given the current military situation in Ukraine. The solution to this difficulty is considered when reserving heat supply by constructing a backup source of thermal energy using alternative types of fuel. A combined thermal scheme for connecting a hot water heat generator using biofuel to the existing city heat supply system is proposed to increase its reliability and survivability, which ensures the efficiency and reliability of operation of the heat supply system during the heating and summer periods. It is shown the possibility of operating a solid fuel heat generator with its power significantly less than the total heat load of the city's heating supply in several operating modes: during the heating period - for heating the return coolant at the inlet to the existing gas boiler house; in the summer period - for the needs of hot water supply in full; in the event of an emergency shutdown of a gas boiler house in winter - to maintain the viability of the heat supply system. The results of a calculation analysis of the operation of a 5,0 MW biofuel heat generator under different operating modes are presented. Heating the return coolant by 4...5 °C in winter, in addition to saving natural gas, prevents low-temperature corrosion of existing gas boilers. In the event of an emergency lack of natural gas supply, the combustion of wood chips ensures the production of thermal energy at the level of thermal losses of the heating network while maintaining the coolant temperature at least 3 °C at the calculated external air temperature. Thanks to the accumulation of thermal energy at night in the summer period in the volume of heating network pipes as a buffer tank, compensation for peak hot water consumption is provided with the available power of the solid fuel boiler house equal to the average load of the hot water supply system. When implementing a project to back up the heat supply system in Lutsk using a combined thermal scheme for connecting a solid fuel boiler house, an increase in the reliability and viability of the system and natural gas savings of 40,5% during a year of operation were achieved

Decomposition behavior of supercritical ethylene under ultra-high temperature and ultra-high pressure

The gas-phase raw materials in many industrial scenarios currently exist in the reactor in a supercritical state. Unlike gas phase molecules, the supercritical molecules usually exhibited dynamic motion patterns in the system, which made them more susceptible to decomposition. Previous researches mainly focused on low-temperature and low-pressure systems, and few research on decomposition behavior of supercritical molecules under ultra-high temperature and ultra-high pressure were studied. This study focused on the decomposition behavior of supercritical ethylene under ultra-high temperature and ultra-high pressure, the effect of triggering conditions on supercritical ethylene decomposition was investigated. In addition, the temperature and pressure change curves during ethylene decomposition were analyzed to obtain evolution time nodes to determine energy accumulation in supercritical states. Moreover, the gas product distribution and derived explosive carbon were characterized for better evaluating the consequences of supercritical ethylene decomposition. This article aimed to provide theoretical basis and data guidance for energy utilization and conversion in ethylene supercritical systems.

Cascade Latent Heat Storage for Solar Cooking Applications

The present investigation explores the potential of multiple phase change material (PCM) based storage for real-time solar thermal applications. There are two types of storage configurations tested in this work for the simultaneous charging and discharging operation, i.e., single PCM-based NaNO3 storage and 2-stage cascade latent heat storage having NaNO3 and NaNO2 as the storage mediums in the consecutive stages. The storage is designed to achieve the end-use temperature condition of 513 K (the highest temperature required for cooking) with the latent thermal energy accumulation capacity of 1 MJ. The study envisages that instead of using a single PCM in the storage unit, 2-stage cascading of the PCMs can improve energy accumulation and retrieval in storage. After 8 hours of operation, none of the storage achieves the complete charging state. The energy accumulated in the NaNO3/NaNO2 cascade storage is found to be 2.6 times higher than the energy accumulated in the NaNO3 storage. NaNO3/NaNO2 storage achieves the desired constant outlet temperature of cold heat transfer fluid for chapati making (531 K) after 165 minutes of operation. At this moment, the latent energy accumulated in the NaNO3 and NaNO3/NaNO2 storage is observed as 35% and 14%, respectively

Surface saturation of drug-loaded hollow manganese dioxide nanoparticles with human serum albumin for treating rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease accompanied by energy depletion and accumulation of reactive oxygen species (ROS). Inorganic nanoparticles (NPs) offer great promise for the treatment of RA because they mostly have functions beyond being drug carriers. However, conventional nanomaterials become coated with a protein corona (PC) or lose their cargo prematurely in vivo, reducing their therapeutic efficacy. To avoid these problems, we loaded methotrexate (MTX) into hollow structured manganese dioxide nanoparticles (H-MnO2 NPs), then coated them with a ‘pseudo-corona’ of human serum albumin (HSA) at physiological concentrations to obtain HSA-MnO2@MTX NPs. Efficacy of MTX, MnO2@MTX, and HSA-MnO2@MTX NPs was compared in vitro and in vivo. Compared to MnO2@MTX, HSA-coated NPs were taken up better by lipopolysaccharide-activated RAW264.7 and were more effective at lowering levels of pro-inflammatory cytokines and preventing ROS accumulation. HSA-MnO2@MTX NPs were also more efficient at blocking the proliferation and migration of fibroblast-like synoviocytes from rats with collagen-induced arthritis. In this rat model, HSA-MnO2@MTX NPs showed better biodistribution than other treatments, specifically targeting the ankle joint. Furthermore, HSA-MnO2@MTX NPs reduced swelling in the paw, regulated pro-inflammatory cytokine production, and limited cartilage degradation and signs of inflammation. These results establish the therapeutic potential of HSA-MnO2@MTX NPs against RA.

Bifacial Photovоltaic Sensor for Insolation Energy Resource Monitoring

Accurate and reliable measurements of the total solar radiation flux make it possible to evaluate the efficiency of using stand-alone photovaltaic systems in various meteorological conditions. These measurements allow more accurately predict in time the energy production volume, accumulator and capacitive storage devices parameters and the payback period. Research purpose was to study the possibility of creating a photoelectric sensor and a method of uninterrupted measurement based on this sensor which allows to measure total solar radiation flux including its direct, diffused and reflected components simultaneously. The photovaltaic sensor with bifacial photosensitivity was manufactured and applied, which is low-inertia comparing to traditional thermoelectric pyranometers, and its spectral sensitivity is quite close to the same parameter of photovoltaic power supply system. It creates the possibility to estimate the insolation level capable to be completely converted into electrical energy without an ineffective heat-generating long-wavelength part of the solar spectrum. A laboratory measuring stand was made to test the sensor's operability. Modeling and experiments’ the sensor parameters were carried out and confirmed its operability. The bifacial photosensitivity sensor allows to control simultaneously direct, diffused and reflected from the earth's surface components of solar radiation, what gives more complete information about the energy potential of the photovoltaic power supply system location.

Experimental Study on the Characteristics of Energy Accumulation before Peak in Coal Rock Combinations with Different Dip Angles

Experimental Study on the Characteristics of Energy Accumulation before Peak in Coal Rock Combinations with Different Dip Angles

Energy and Protein Requirements of Growing Lambs in Colombian Highlands.

Determining the nutritional requirements of lambs is necessary to formulate balanced rations and contribute to sustainable sheep production systems. However, limited information is available regarding the nutritional requirements of growing lambs in the Colombian highlands. Twenty-two Romney Marsh males were used. Initially, four lambs were slaughtered at 20 kg body weight (BW). The remaining 18 lambs were distributed into two groups, according to BW (light: 20 BW and heavy: 30 kg BW). Lambs were randomly allocated into one of three different nutritional schemes, according to voluntary intake (no restriction, and 25 and 50% restriction). All the animals received a totally mixed ration. When a voluntary-fed lamb gained 10 kg BW, the two other lambs restricted to 25 and 50% were slaughtered and dissected into components to determine protein and gross energy concentration. Energy and protein accumulation were analyzed through regression analysis. The net energy for maintenance was 82.3 kcal/kg BW0.75, while the energy efficiencies for maintenance and gain were 0.72 and 0.29, respectively. Crude protein for maintenance was 1.78 g/kg BW0.75, and the nitrogen efficiencies for maintenance and gain were 0.41 and 0.27, respectively. The maintenance requirement of energy was greater, while protein was similarly related to values reported in the literature; however, the efficiency of energy and protein use was lower in growing lambs. These results suggested that estimating energy and nitrogen requirements for growing lambs must be adjusted in Colombian highland conditions.

High-speed shearing: An ultra-fast internal energy accumulation method for nucleation of SnZnO in photocatalysis

Zinc oxide (ZnO) nanoparticles and their derivatives, appreciated for their cost-effectiveness, simplicity in synthesis, and versatile applications, have garnered considerable attention. However, unraveling the nucleation and growth mechanisms of ZnO nanoparticles remains a formidable challenge. By comparing the magnetic stirring synthesis (MSS) and high-speed shearing (HSS) methods, we conducted time-dependent calculations of pressure and velocity at various positions in the solution. Under the powerful shearing force, which is the key route to accumulate internal energy (Ein), molecules could achieve at most 174 eV Ein in HSS instead of 0.81 eV Ein in MSS. Molecules could obtain enough energy for nucleation in just 1.03 μs. HSS, utilizing a high-speed rotor for robust shear forces, not only modifies nucleation patterns but also facilitates effective mixing in multi-element systems. SnxZn1−xO1+x nanoparticles prepared through HSS display uniform size, markedly reduced agglomeration, homogeneous element distribution, and a more pronounced bandgap change, causing a decrease in photocatalytic activity to the original 11.2 %.

Dynamic Programming-Based Track-before-Detect Algorithm for Weak Maneuvering Targets in Range–Doppler Plane

This paper focuses on detecting and tracking maneuvering weak targets in the range–Doppler (RD) plane with the track-before-detect (TBD) algorithm based on dynamic programming (DP). Traditional DP-TBD algorithms integrate target detection and tracking in their framework while searching the paths provided by a predefined model of the kinematic properties within the constraints allowed. However, both the approximate motion model used in the RD plane and the model mismatch caused when the target undergoes a maneuver can degrade the TBD performance sharply. To address these issues, this paper accurately describes the evolution of the RD equation based on Constant Acceleration (CA) and Coordinated Turn (CT) motion models with the process noise in the Cartesian coordinate system, and it also employs a recursive method to estimate the parameters in the equations for efficient energy accumulation and path searches. Facing the situation that targets energy accumulation during the DP iteration process will lead to an expansion of the target energy accumulation process. This paper designs a more efficient Optimization Function (OF) to inhibit the expansion effect, improve the resolution of the nearby targets, and increase the detection probability of the weak targets simultaneously. In addition, to search the trajectory more efficiently and accurately, we improved the process of DP multi-frame accumulation, thus reducing the computation amount of large-scale searches. Finally, the effectiveness of the proposed method for CA and CT motion target detection and tracking is verified by many of the simulation experiments that were conducted in this paper.

Solid-mechanics analysis and modeling of the alloyed ohmic contact proximity in GaN HEMTs using µRaman spectroscopy

This study explores the impact of alloyed ohmic contact separation on ungated GaN high electron mobility transistors (HEMTs) lattice stress by employing Raman spectroscopy and solid mechanics simulations for comprehensive analysis. Focusing on the substantial stresses exerted by ohmic contacts, our research introduces a novel mechanical calibration procedure. The proposed procedure demonstrates that the stress in the GaN buffer can be precisely modelled using Raman measurements taken from patterns of varying length, which in return reveals the impact of ohmic contacts on stress. We show that this technique shows a good alignment to the Raman measurement results. Moreover, we identify ohmic contact edges as potential sites for defect generation due to the accumulation of substantial elastic energy, a finding supported by experimental observations of crack formations in related studies. Our calibrated mechanical model not only enhances the understanding of stress distributions within GaN HEMTs but also lays the groundwork for future improvements in electro-thermo-mechanical simulations.

Analysis and Comparison of Fourier and Wavelet Transforms: Application for the Study of Seismic Source Parameters, Case of the 2001 Arequipa Earthquake

The purpose of this study is to apply the spectral analysis technique to the aftershocks of the 2001 Arequipa earthquake (Mw=8.4), based on the Fourier and Wavelet transforms.The data corresponds to the world network (IRIS), which has a station called NNA that is located in Peru. Together, 10 records corresponding to replicas registered during a period of 10 days after the main event have been analyzed. The methodology used in this study was based on the SAC software that stands for "Seismic Analysis Code". As a result of the Fourier transform, the fracture radius values obtained are in the range of 0.21 to 1.15km, the stress drop values for the analyzed aftershocks are between 0.60 to 38.08Mpa, the Energy Magnitude is from 3.36 to 4.42Me; for Wavelet: the frequency content which presents the values between 0.18 to 0.30 Hz, The maximum radiated energy between 25.70 to 40.80, the values obtained are in the range of 92.18 to 146.12s. The analysis and comparison of the transforms showed that with the Fourier transform different parameters can be determined by applying spectral analysis, however, with the wavelet transform the maximum radiated energy was determined This study contributes to the literature by finding these parameters of both transforms as it is of vital importance to determine the zones of energy accumulation that would cause earthquakes of great magnitude in the future.

Investigation of quantitative precursory indicators for rock failure using spatio-temporal characteristics of velocity

Stress redistribution and crack development are prominent features in rock failure. However, these processes are complex and challenging to analyze, making early warning of instability in rock engineering difficult. To characterize the rock failure process and obtain reliable precursory indicators, the imaging method that combines active and passive sources was employed to construct the velocity field during the rock failure process in this study. The micro-crack propagation law and its potential connection with the stress environment were investigated by mapping the velocity field, the acoustic emission (AE) density field, and the energy field. Moreover, the Mutation Trend Coefficient (MTC) and Deformation Coefficient (DC) were proposed as precursory indicators of instability based on the spatio-temporal correlation and directional differences of velocity evolution. Results show that the nucleation of AE sources and the release of energy accumulation are key to the formation of the velocity gradient, and progressive rock failure is accompanied by the intensification of velocity anisotropy. Additionally, low-velocity regions usually preferentially extend in the direction parallel to the principal stress, while expansion in the direction vertical to the principal stress is dominant in the plastic stage, indicating that the stress environment controls the spatial heterogeneity of the velocity field. The evolution trend of precursor indicators shows that the increase of MTC from a low value and the continuous decrease of DC can be regarded as the initiation of rock secondary cracks. The proposed indicators and method not only provide beneficial complements to the understanding of the evolution mechanism of rock damage but also have potential in the early warning and identification of the early stage of crack propagation, offering references for the safety prevention and control of rock engineering disasters.