A CNN-Based Single-Stage Occlusion Real-Time Target Detection Method

Aiming at the problem of low accuracy of traditional target detection methods for target detection in endoscopes in substation environments, a CNN-based real-time detection method for masked targets is proposed. The method adopts the overall design of backbone network, detection network and algorithmic parameter optimisation method, completes the model training on the self-constructed occlusion target dataset, and adopts the multi-scale perception method for target detection. The HNM algorithm is used to screen positive and negative samples during the training process, and the NMS algorithm is used to post-process the prediction results during the detection process to improve the detection efficiency. After experimental validation, the obtained model has the multi-class average predicted value (mAP) of the dataset. It has general advantages over traditional target detection methods. The detection time of a single target on FDDB dataset is 39 ms, which can meet the need of real-time target detection. In addition, the project team has successfully deployed the method into substations and put it into use in many places in Beijing, which is important for achieving the anomaly of occlusion target detection.

深水采油树Spring-Seal密封圈接触模型构建与实验测试

为提高深水采油树在高压、高温、低温等工况下长时间工作的稳定性,对采油树密封圈进行重新设计,提出Spring-Seal密封圈(以下简称S密封圈);基于赫兹接触理论、填料密封接触理论,重新构建S密封圈接触力学模型;建立有限元仿真分析模型,分析不同条件下S密封圈的密封性能,同时验证新建接触模型的合理性;利用实验测试S密封圈的实际密封效果。研究结果表明:S密封圈在高压、高温、低温等工况下能够长时间稳定工作且密封性能良好。研究结果可为S密封圈的接触研究及工程运用提供理论参考。

Sealing capacity evaluation of underground gas storage under intricate geological conditions

Evaluating underground gas storage(UGS)sealing capacity is essential for its safe construction and operational efficiency.This involves evaluating both the static sealing capacity of traps during hydrocarbon accumulation and the dynamic sealing capacity of UGS under intensive gas injection and withdrawal,and alternating loads.This study detailed the methodology developed by Sinopec.The approach merges disciplines like geology,geomechanics,and hydrodynamics,employing both dynamic-static and qualitative-quantitative analyses.Sinopec's evaluation methods,grounded in the in situ stress analysis,include mechanistic studies,laboratory tests,geological surveys,stress analysis,and fluid-solid interactions.Through tests on the static and dynamic sealing capacity of UGS,alongside investigations into sealing mechanisms and the geological and geomechanical properties of cap rocks and faults,A geomechanics-rock damage-seepage mechanics dynamic coupling analysis method has been developed to predict in situ stress variations relative to pore pressure changes during UGS operations and evaluate fault sealing capacity and cap rock integrity,thereby setting the maximum operational pressures.Utilizing this evaluation technique,Sinopec has defined performance metrics and criteria for evaluating the sealing capacity of depleted gas reservoirs,enabling preliminary sealing capacity evaluations at UGS sites.These evaluations have significantly informed the design of UGS construction schemes and the evaluation of fault sealing capacity and cap rock integrity during UGS operations.

Interfacial friction effects on sealing performances of elastomer packer

Elastomer sealing performance is of critical importance for downhole tools application including the use of fracturing(Frac)plugs during multi-stage hydraulic fracking.In practice sealing performances of such plugs are normally evaluated through pressure tests,and in numerical simulation studies,maximum contact stress,average contact stress and contact length data are used to determine sealing quality between a packer and casing.In previous studies,the impact of friction forces on sealing performance is often overlooked.This work aims to fill this knowledge gap in determining the influence of friction forces on elastomer packer sealing performances.We first determined the most appropriate constitutive hyperelastic model for the elastomers used in frac plug.Then we compared analytical calculation results with Finite Element Analysis simulation using a simplified tubular geometry and showed the significant influences on interfacial friction on elastomer packer stress distribution,deformation,and contact stress after setting.With the demonstration of validity of FEA method,we conducted systematic numerical simulation studies to show how the interfacial friction coefficients can affect the maximum contact stress,average contact stress,contact stress distribution,and maximum mises stress for an actual packer used in plug products.In addition,we also demonstrated how the groove in a packer can affect packer deformation and evolvement during setting with the consideration of interfacial stress.This study underscores the critical role that friction forces play in Frac plug performance and provides a new dimension for optimizing packer design by controlling interfacial interactions at the packer contact surfaces.

Evolution and Application of Sealing Ability of Gypsum Caprocks under Temperature-Pressure Coupling:An Example of the ZS5 Well in the Tazhong Area of the Tarim Basin

Gypsum caprocks'sealing ability is affected by temperature-pressure coupling.Due to the limitations of experimental conditions,there is still a lack of triaxial stress-strain experiments that simultaneously consider changes in temperature and pressure conditions,which limits the accuracy of the comprehensive evaluation of the brittle plastic evolution and sealing ability of gypsum rocks using temperature pressure coupling.Triaxial stress-strain tests were utilized to investigate the differences in the evolution of the confinement capacity of gypsum rocks under coupled temperaturepressure action and isothermal-variable pressure action on the basis of sample feasibility analysis.According to research,the gypsum rock's peak and residual strengths decrease under simultaneous increases in temperature and pressure over isothermal pressurization experimental conditions,and it becomes more ductile.This reduces the amount of time it takes for the rock to transition from brittle to plastic.When temperature is taken into account,both the brittle–plastic transformation's depth limit and the lithological transformation of gypsum rocks become shallower,and the evolution of gypsum rocks under variable temperature and pressure conditions is more complicated than that under isothermal pressurization.The sealing ability under the temperature-pressure coupling is more in line with the actual geological context when the application results of the Well#ZS5 are compared.This provides a theoretical basis for precisely determining the process of hydrocarbon accumulation and explains why the early hydrocarbon were not well preserved.

Fracture sealing performance of granular lost circulation materials at elevated temperature:A theoretical and coupled CFD-DEM simulation study

Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulation.However,conventional LCMs seem ineffective in high-temperature formations.This may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature conditions.To understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in fractures.We summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling fluid.We conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing temperatures.The results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid viscosity.Smaller,softer,and less frictional LCM particles have lower bridging probability and slower bridging initiation.Smaller particles tend to form dual-particle bridges rather than single-particle bridges.These result in a deeper,tighter,but unstable sealing zone.Reduced drilling fluid viscosity leads to faster and shallower sealing zones.

Dynamic evaluation on sealing capacity of caprocks of the Meso-Neoproterozoic reservoirs in Ordos Basin,China

The Meso-Neoproterozoic is a new play in the Ordos Basin.A deeper understanding about the dynamic relationship between the caprocks and the source rocks is needed.Based on the comprehensive analysis of hydrocarbon source development characteristics of the Meso-Neoproterozoic and its overlying strata,as well as the formation contact relationships,lithology characteristics and exploratory drilling data,it is recognized that the Meso-Neoproterozoic contains two types of petroleum accumulation assemblage,that is,the“self-sourced indigenous”and“upper source rock-lower reservoir”assemblages.The former is mainly controlled by the development and distribution of source rocks of the Changcheng System,with the Lower Cambrian shale sequence as its caprock.The later is controlled by the superposition between the Meso-Neoproterozoic and its overlying source rocks and this assemblage is mainly distributed in Hangjinqi and Pingliang areas with the Carboniferous-Permian shale sequence as its caprock.The dynamic evaluation on the displacement pressure serves to reconstruct the displacement pressure history of the caprock.The results show that the shale sequence of the Cambrian Maozhuang Formation in well XY 1 in the southern Ordos Basin has possibly acquired the ability of sealing natural gas since the early of Late Triassic.Its displacement pressure increased rapidly up to 20 MPa during the Late Triassic-Jurassic and keeps at 9.2 MPa at present,indicating fair sealing ability.The Carboniferous-Permian caprocks in Hangjinqi area could have acquired the ability to seal natural gas in the Late Jurassic-Early Cretaceous,and the present-day displacement pressure is 9e12 MPa,indicating good sealing ability.The upper Paleozoic caprock in Pingliang area has been able to seal natural gas since the Early Jurassic,with a maximum displacement pressure of 23 MPa during the Cretaceous period and a current value of 17 e20 MPa,indicative of strong ability to seal natural gas.The sealing ability of caprocks of both the“selfsourced indigenous”and“upper source rock-lower reservoir”assemblages has come into being earlier than or at least no later than the peak gas generation of the source rocks and therefore the caprocks are dynamically effective in geohistory.The Meso-Neoproterozoic reservoirs in the Ordos Basin are well preserved and probabally of better potential for exploration in terms of the caprock-source rock combination.

Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units.The mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation model.UDF(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh technology.The results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually decreases.And the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely manner.The maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance amplitude.The mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial values.Compared with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and leakage.During actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

Evaluation of the dynamic sealing performance of cap rocks of underground gas storage under multi-cycle alternating loads

The static sealing of underground gas storage(UGS),including the integrity of cap rocks and the stability of faults,is analyzed from a macro perspective using a comprehensive geological evaluation method.Changes in pore structure,permeability,and mechanical strength of cap rocks under cyclic loads may impact the rock sealing integrity during the injection and recovery phases of UGS.In this work,the mechanical deformation and failure tests of rocks,as well as rock damage tests under alternating loads,are conducted to analyze the changes in the strength and permeability of rocks under multiple-cycle intense injection and recovery of UGS.Additionally,this study proposes an evaluation method for the dynamic sealing performance of UGS cap rocks under multi-cycle alternating loads.The findings suggest that the failure strength(70%)can be used as the critical value for rock failure,thus providing theoretical support for determining the upper limit of operating pressure and the number of injection-recovery cycles for the safe operation of a UGS system.

Preparation and property of seal coating for gas turbine compressor

Double-layer structure of seal coating which consisted of a Ni5Al bond coating and a Ni25 graphite top coating were prepared on steel substrate of gas turbine compressor cylinder block.Bond coating was prepared by atmospheric plasma spraying and top coating was prepared by flame spraying.The microstructure,mechanical properties and abradability of the coating were characterized by scanning elec-tron microscope(SEM),hardness tester,universal testing machine,thermal shock testing machine and abradability testing machine.The res-ults show that the overall spraying structure of the seal coating is uniform,the nickel metal phase is the skeleton supporting the entire coat-ing,and the coating is well bonded without separation.The seal coating has a bonding strength of not less than 7.7 MPa,excellent thermal stability,and thermal shock resistance cycle numbers at 500℃more than 50;the scratch length,deepest invasion depth and wear amount of the coating increase with rise of test temperature,with almost no coating adhesion,indicating that the seal coating has excellent abradability.

SEAL428采集设备原理分析

本文从Sercel公司用于陆地和海上勘探的428系列地震仪器产品性能特点出发,通过对比分析,总结海洋SEAL428系统的设计理念和数据采集原理。文章从两者的野外采集设备布设和连接方式切入,对比两套系统的设备架构、数据传输、设备布设灵活性、带道能力、采集设备种类、采集设备故障排查等方面的异同。重点对SEAL428地震采集仪器的数据采集原理进行分析,对SEAL428的“鬼对”传输技术、数字滤波器原理等进行深入探讨,以期为国内海洋物探装备技术提升提供参考。

Study on Sealing Characteristics of Sliding Seal Assembly of Aircraft Hydraulic Actuator

The hydraulic actuator,known as the"muscle"of military aircraft,is responsible for flight attitude adjustment,trajectory control,braking turn,landing gear retracting and other actions,which directly affect its flight efficiency and safety.However,the sealing assembly often has the situation of over-aberrant aperture fit clearance or critical over-aberrant clearance,which increases the failure probability and degree of movable seal failure,and directly affects the flight efficiency and safety of military aircraft.In this paper,the simulation model of hydraulic actuator seal combination is established by ANSYS software,and the sealing principle is described.The change curve of contact width and contact pressure of combination seal under the action of high-pressure fluid is drawn.The effects of different oil pressure,fit clearance and other parameters on the sealing performance are analyzed.Finally,the accelerated life test of sliding seal components is carried out on the hydraulic actuator accelerated life test rig,and the surface morphology is compared and analyzed.The research shows that the O-ring is the main sealing element and the role of the check ring is to protect and support the O-ring to prevent damage caused by squeezing into the fit clearance,so the check ring bears a large load and is prone to shear failure.Excessive fit clearance is the main factor affecting the damage of the check ring,and the damage parts are mainly concentrated at the edge of the sealing surface.This paper provides a theoretical basis for the design of hydraulic actuator and the improvement of sealing performance.

Application of Choquet Integral-Importance-Performance Analysis and TOPSIS Methods in Approaching the Preference Factors of Calligraphy and Seal Engraving Imagery

Classical Chinese characters,presented through calligraphy,seal engraving,or painting,can exhibit different aesthetics and essences of Chinese characters,making them the most important asset of the Chinese people.Calligraphy and seal engraving,as two closely related systems in traditional Chinese art,have developed through the ages.Due to changes in lifestyle and advancements in modern technology,their original functions of daily writing and verification have gradually diminished.Instead,they have increasingly played a significant role in commercial art.This study utilizes the Evaluation Grid Method(EGM)and the Analytic Hierarchy Process(AHP)to research the key preference factors in the application of calligraphy and seal engraving imagery.Different from the traditional 5-point equal interval semantic questionnaire,this study employs a non-equal interval semantic questionnaire with a golden ratio scale,distinguishing the importance ratio of adjacent semantic meanings and highlighting the weighted emphasis on visual aesthetics.Additionally,the study uses Importance-Performance Analysis(IPA)and Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)to obtain the key preference sequence of calligraphy and seal engraving culture.Plus,the Choquet integral comprehensive evaluation is used as a reference for IPA comparison.It is hoped that this study can provide cultural imagery references and research methods,injecting further creativity into industrial design.

Microstructure and Magnetic Properties of Anisotropic Nd-Fe-B Magnets Fabricated by Single-Stage Hot Deformation

Anisotropic Nd-Fe-B magnets were fabricated by the single stage hot deformation (SSHD) method. The magnetic properties of the anisotropic Nd-Fe-B magnets are as follows: the maximum energy product is 234.7 kJ·m-3 , remanence 1.16 T and coercivity 684.3 kA·m-1. A study of the relationship between microstructure and magnetic properties for the anisotropic Nd-Fe-B magnets was carried out. The results show that the grains of Nd2Fe14B have grown up preferentially along the direction perpendicular to the pressing direction.

Fatigue Properties of RPC under Cyclic Loads of Single-stage and Multi-level Amplitude

Fatigue properties of Reactive Powder Concrete （RPC） under axial compression of single-stage and multi-level amplitude in cycles were studied. The tests reveal the fatigue life, the strain and residual life of the RPC samples. Through the analysis of the test results under cyclic loads of single amplitude, the S-N curve of RPC and the evolution rule of macro-damage of RPC were presented, which can be divided into latency stage, stable development stage and instability development stage according to the evolution pattern of the fatigue crack. Accordingly, the development of longitudinal deformation presents the similar three-stage-model, and the proportion of each stage is 15%, 75%, and 10%. According to test results, the fatigue strength reduction factor is 0.564. We brought forward an empirical formula to predict the life of RPC via total longitudinal strain and got the evolving rule for the residual strength of the RPC. The analysis of the test results under cyclic loads of multi-level amplitude shows that the strain under this loading pattern experiences three stages. The characteristic value for the residual strain was obtained. The irreversible damage and non-linear evolution of RPC was described by the development of the residual plastic strain.

A High-Efficiency Single-Stage Low-Power Photovoltaic Inverter System with Maximum Power Point Tracking Control

This paper proposes a single-stage inverter system with maximum power point tracking control (MPPT) applicable in low-power photovoltaic (PV) energy conversion systems. The proposed system is successfully implemented using a single digital signal processor (DSP) TMS320F2808. The proposed single-stage inverter system has the following features: 1) the ability to harvest the maximum PV power using two simple and effective current sampling methods;2) flexible topology based on the positioning of DC link capacitor on the outside of the inverter bridge circuits;3) reduced volume and higher efficiency than the conventional two-stage inverters, and 4) MPPT accuracy of 99.3% with overall efficiency of 90% under the full-load condition.

Study on the effect of thermal deformation on the liquid seal of high-temperature molten salt pump in molten salt reactor

The high-temperature molten salt pump is the core equipment in a molten salt reactor that drives the flow of the molten salt coolant.Rotor stability is key to the continuous and reliable operation of the molten salt pump,and the liquid seal at the wear ring can affect the dynamic characteristics of the rotor system.When the molten salt pump is operated in the hightemperature molten salt medium,thermal deformation of the submerged parts inevitably occurs,changing clearance between the stator and rotor,affecting the leakage and dynamic characteristics of the seal.In this study,the seal leakage,seal dynamic characteristics,and rotor system dynamic characteristics are simulated and analyzed using finite element simulation software based on two cases of considering the effect of seal thermal deformation effect or not.The results show a significant difference in the leakage characteristics and dynamic characteristics of the seal obtained by considering the effect of seal thermal deformation and neglecting the effect of thermal deformation.The leakage flow rate decreases,and the first-order critical speed of the seal-bearing-rotor system decrease after considering the seal’s thermal deformation.

Air tightness of compressed air storage energy caverns with polymer sealing layer subjected to various air pressures

During the operation of compressed air storage energy system,the rapid change of air pressure in a cavern will cause drastic changes in air density and permeability coefficient of sealing layer.To calculate and properly evaluate air tightness of polymer sealing caverns,the air-pressure-related air density and permeability must be considered.In this context,the high-pressure air penetration in the polymer sealing layer is studied in consideration of thermodynamic change of the cavern structure during the system operation.The air tightness model of compressed air storage energy caverns is then established.In the model,the permeability coefficient and air density of sealing layer vary with air pressure,and the effectiveness of the model is verified by field data in two test caverns.Finally,a compressed air storage energy cavern is taken as an example to understand the air tightness.The air leakage rate in the caverns is larger than that using air-pressure-independent permeability coefficient and air density,which is constant and small in the previous leakage rate calculation.Under the operating pressure of 4.5-10 MPa,the daily air leakage in the compressed air storage energy cavern of Yungang Mine with high polymer butyl rubber as the sealing material is 0.62%,which can meet the sealing requirements of compressed air storage energy caverns.The air tightness of the polymer sealing cavern is mainly affected by the cavern operating pressure,injected air temperature,cavern radius,and sealing layer thickness.The cavern air leakage rate will be decreased to reduce the cavern operating pressure the injection air temperature,or the cavern radius and sealing layer thickness will be increased.

Preparation and property of self-sealed plasma electrolytic oxide coating on magnesium alloy

Plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys However,its application is limited due to its defects.This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition.The morphology and structure were characterized by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and X-ray diffractometer (XRD).Image-Pro Plus 6.0 was used to determine the porosity of the coating,which was decreased from 8.53%to 0.51%.Simultaneously,the coating thickness was increased by a factor of four.The anti-corrosion performance of each sample was evaluated using electrochemical tests,and the findings revealed that the corrosion current density of coatings (i_(corr)) of the samples were lowered from 9.152×10^(-2) to 6.152×10^(-4) mA·cm^(-2),and the total resistance (R_(T)) of the samples were enhanced from 2.19×10^(4) to 2.33×10^(5)Ω·cm^(2).The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h.In addition,the mechanism of PEO self-sealing behavior was described in this article.

MRI insight on multiphase flow in hydrate-bearing sediment and development mechanism of hydrate seal

Gas and water migration through the hydrate-bearing sediment are characteristic features in marine gas hydrate reservoirs worldwide.However,there are few experimental investigations on the effect of water-gas flow on the gas hydrate reservoir.In this study,gas-water migration in gas hydrate stability zone(GHSZ)was investigated visually employing a high-resolution magnetic resonance imaging(MRI)apparatus,and the formation of hydrate seal was experimentally investigated.Results revealed that normal flow of gas-water at the low flow rate of 1–0.25 mL/min will induce the hydrate reformation.Conversely,higher gas-water flow rates(at 2–0.5 and 4–1 mL/min)need higher reservoir pressure to induce the hydrate reformation.In addition,the hydrate reformation during the gas-water flow process produced the hydrate seal,which can withstand an over 9.0 MPa overpressure.This high overpressure provides the development condition for the underlying gas and/or water reservoir.A composite MRI image of the whole hydrate seal was obtained through the MRI.The pore difference between hydrate zone and coexistence zone produces a capillary sealing effect for hydrate seal.The hydrate saturation of hydrate seal was more than 51.6%,and the water saturation was more than 19.3%.However,the hydrate seal can be broken through when the overpressure exceeded the capillary pressure of the hydrate seal,which induced the sudden drop of reservoir pressure.This study provides a scientific explanation for the existence of high-pressure underlying gas below the hydrate layer and is significant for the safe exploitation of these common typical marine hydrate reservoirs.