The taxonomy of Neotropical Apicotermitinae, considering the absence of a soldier caste, requires identification to be based on morphological characters of workers and imagoes, especially the characteristics of the gut coiling pattern, which, due to their complexity, demand specialized training. The aim of this study was to describe a new genus and species of the subfamily Apicotermitinae from the Caatinga dry forest, a type of vegetation that dominates the semi-arid region of northeastern Brazil. To achieve this, were used external morphological characters and those of the gut of workers, as well as molecular data (COI, COII, and 16S). The main diagnostic features of the genus include the ring-shaped arrangement of the enteric valve seating and the enteric valve armature with three sclerotized hemispherical plates of different sizes, with the central one being larger than the others, all armed with spines. Phylogenetic analyses (BI and ML) suggest Triclavitermes catoleensis sp. nov. is related to Dissimulitermes invisibilis and Rustitermes boteroi. The distribution of Triclavitermes catoleensis sp. nov. is currently restricted to the Caatinga ecosystems, but it is possible that this species also occurs in other ecosystems along the dry diagonals of South America which includes the Caatinga, Cerrado, and Chaco.

In modern industry, the spring full-lift safety valve is a key device for safe pressure relief of pressure-bearing systems. Its valve seat sealing surface is easily damaged after long-term use, causing internal leakage, resulting in safety hazards and economic losses. Therefore, it is of great significance to quickly and accurately diagnose its internal leakage state. Among the current methods for identifying fluid machinery faults, model-based methods have difficulties in parameter determination. Although the data-driven convolutional neural network (CNN) has great potential in the field of fault diagnosis, it has problems such as hyperparameter selection relying on experience, insufficient capture of time series and multi-scale features, and lack of research on valve internal leakage type identification. To this end, this study proposes a safety valve internal leakage identification method based on high-frequency FPGA data acquisition and improved CNN. The acoustic emission signals of different internal leakage states are obtained through the high-frequency FPGA acquisition system, and the two-dimensional time–frequency diagram is obtained by short-time Fourier transform and input into the improved model. The model uses the leaky rectified linear unit (LReLU) activation function to enhance nonlinear expression, introduces random pooling to prevent overfitting, optimizes hyperparameters with the help of horned lizard optimization algorithm (HLOA), and integrates the bidirectional gated recurrent unit (BiGRU) and selective kernel attention module (SKAM) to enhance temporal feature extraction and multi-scale feature capture. Experiments show that the average recognition accuracy of the model for the internal leakage state of the safety valve is 99.7%, which is better than the comparison model such as ResNet-18. This method provides an effective solution for the diagnosis of internal leakage of safety valves, and the signal conversion method can be extended to the fault diagnosis of other mechanical equipment. In the future, we will explore the fusion of lightweight networks and multi-source data to improve real-time and robustness.

As the core device for protecting the safety of the pressure-bearing system, the spring full-open safety valve is prone to various forms of valve seat sealing surface damage after long-term opening and closing impact, corrosion, and medium erosion, which may lead to internal leakage. In view of the problems that the high-frequency acoustic emission signal of the internal leakage of the safety valve has, namely, a large number of energy-overlapping areas in the frequency domain, the overall signal presents broadband characteristics, large noise content, and no obvious time-frequency characteristics. A composite denoising method, IWTD, improved wavelet threshold function with dual adjustable factors, and the improved VMD algorithm is proposed. In view of the problem that the optimal values of the dual adjustment factors a and b of the function are difficult to determine manually, an improved dung beetle optimization algorithm is proposed, with the maximum Pearson coefficient as the optimization target; the optimization is performed within the value range of the dual adjustable factors a and b, so as to obtain the optimal value. In view of the problem that the key parameters K and α in VMD decomposition are difficult to determine manually, the maximum Pearson coefficient is taken as the optimization target, and the improved dung beetle algorithm is used to optimize within the value range of K and α, so as to obtain the IVMD algorithm. Based on the IVMD algorithm, the characteristic decomposition of the internal leakage acoustic emission signal occurs after the denoising of the IWTD function is performed to further improve the denoising effect. The results show that the Pearson coefficients of all types of internal leakage acoustic emission signals after IWTD-IVMD composite noise reduction are greater than 0.9, which is much higher than traditional noise reduction methods such as soft and hard threshold functions. Therefore, the IWTD-IVMD composite noise reduction method can extract more main features out of the measured spring full-open safety valve internal leakage acoustic emission signals, and has a good noise reduction effect. Feature recognition after noise reduction can provide a good evaluation for the safe operation of the safety valve.

This study focuses on the optimization of valve assemblies in downhole rod pumping units (DRPUs), which remain the predominant artificial lift technology in oil production worldwide. The research addresses the critical issue of premature failures in DRPUs caused by leakage in valve pairs, i.e., a problem that accounts for approximately 15% of all failures, as identified in a statistical analysis of the 2022 operational data from the Uzen oilfield in Kazakhstan. The leakage is primarily attributed to the accumulation of mechanical impurities and paraffin deposits between the valve ball and seat, leading to concentrated surface wear and compromised sealing. To mitigate this issue, a novel valve assembly design was developed featuring a flow turbulizer positioned beneath the valve seat. The turbulizer generates controlled vortex motion in the fluid flow, which increases the rotational frequency of the valve ball during operation. This motion promotes more uniform wear across the contact surfaces and reduces the risk of localized degradation. The turbulizers were manufactured using additive FDM technology, and several design variants were tested in a full-scale laboratory setup simulating downhole conditions. Experimental results revealed that the most effective configuration was a spiral plate turbulizer with a 7.5 mm width, installed without axis deviation from the vertical, which achieved the highest ball rotation frequency and enhanced lapping effect between the ball and the seat. Subsequent field trials using valves with duralumin-based turbulizers demonstrated increased operational lifespans compared to standard valves, confirming the viability of the proposed solution. However, cases of abrasive wear were observed under conditions of high mechanical impurity concentration, indicating the need for more durable materials. To address this, the study recommends transitioning to 316 L stainless steel for turbulizer fabrication due to its superior tensile strength, corrosion resistance, and wear resistance. Implementing this design improvement can significantly reduce maintenance intervals, improve pump reliability, and lower operating costs in mature oilfields with high water cut and solid content. The findings of this research contribute to the broader efforts in petroleum engineering to enhance the longevity and performance of artificial lift systems through targeted mechanical design improvements and material innovation.

Abstract Aiming at the problem that large-scale ultra-high-pressure pneumatic ball valves opened and closed at large explosion instantaneously are prone to fatigue failure due to dynamic stress concentration under transient impact loads, this study proposes a multi-physics field coupling structural strength optimization design method based on finite element method. A transient dynamic model is constructed through an explicit dynamics algorithm to simulate the dynamic response under high-frequency impact loads during the blasting opening and closing process. Fluid-Structure Interaction (FSI) is introduced to analyze the interaction between fluid impact force and structural deformation. At the same time, the elastic modulus degradation effect of tungsten carbide/nickel-based alloy composites caused by frictional heat is considered, and the wear rate is calculated based on the wear model Archard. Secondly, the variable density method is used to perform topological optimization on the key areas of the valve body (such as the contact surface between the sphere and the valve seat), the internal rib layout is reconstructed to reduce stress concentration, and geometric parameters such as the valve seat inclination angle and the sphere diameter are screened. The nondominated sorting genetic algorithm (NSGA-II) is used to achieve the coordinated optimization of the leakage rate and the coating’s wear resistance and structural strength. By building an ultra-high pressure burst test bench, this paper combines strain gauges and high-speed cameras to verify the accuracy of the model and corrects the simulation boundary conditions based on the Kalman filter algorithm. The experiment shows that after optimization, the maximum equivalent stress peak of the valve body is reduced by 32.7%, the leakage rate is reduced to 0.008%, and the dynamic fatigue life is increased to 1.5 × 105 cycles under the commonly used engineering stress amplitude. The stress error between the simulation and the test is always less than 5%. The multi-objective optimization method under dynamic load in this paper can provide a theoretical basis for the reliable design and intelligent operation and maintenance of ultra-high pressure and ultra-wear-resistant pneumatic ball valves and promote their engineering applications in the fields of hydrogen energy storage and transportation and chemical industry.

In high-pressure gas field exploitation, wellhead fluids contain not only gas phases but also liquid water and solid particles, thus the valve seat and core of high-pressure throttle valves are extremely susceptible to failure caused by complex fluid erosion, which seriously threatens gas field production and human safety. Historical development of erosion theory is surveyed initially, followed by a summary of current erosion theories, highlighting the limitations of single-theory formulations in modelling complex erosion processes. The erosion research framework for solid-laden fluids is subsequently described, comprising governing equations, turbulence models, calculation methods, particle behavior models and erosion models. Besides, structural factors, flow conditions, solid particle properties, substrate properties and interaction between erosion wear and corrosion influencing throttle valve erosion wear are summarized, clarifying the mechanisms and recent investigation finding of various factors. Following that, two research methods for erosion wear-experimental and numerical simulation methods are introduced comprehensively. Finally, trends of future research on erosion wear in high-pressure throttle valves are predicted.

A new high carbon Fe-12.5Cr-1.5Mo-6V-2.5 W tool steel powder, designated HCrVC, was developed and successfully water atomized. The high carbon content protects Cr from oxidation during water atomisation and results in ∼50 vol% total carbides and 1050 HV0.05 hardness. A final density of 6.90 g cm −3 was achieved for a mix with 20 wt% HCrVC in a low alloy matrix, suitable for wear-resistant valve seat inserts via press and sinter powder metallurgy. The simplicity and robustness of the powder production process enable a cost-effective, lean tool steel for the competitive automotive market. Notably, the sintered material exhibited comparable or superior high-temperature wear resistance to wrought AISI D2 and H13 steels at 300 °C and 450 °C, confirming its suitability for elevated-temperature applications.

The mass flow rate of the fuel-air mixture can vary due to the geometry and dimensions of the valve seat and orifice plate at the tip of the port fuel injector. This study aims to reduce the standard deviation of the mass flow rate by optimizing four design parameters of the valve seat defined at the top (CHA1 – the angle between the valve seat and the bore wall and CHH1– its horizontal distance) and the bottom (CHA2 – the angle of the chamfer from the bottom of the valve seat and CHV2 – its vertical distance) of the edge breaks to guarantee a constant mass flow rate during its operation. The sensitivity analysis is implemented with the CFD simulation to generate the Design of Experiment (DOE) using ANSYS CFX and optiSLang. This created the correlation between design parameters and the averaged mass flow rate. The results indicate that CHA2 was the most impacting parameter on the mass flow rate. The Robust Design Optimization (RDO) is performed based on the Metamodel of Optimal Prognosis (MOP). Furthermore, the optimization loop processes the correlation function obtained from MOP using the Evolutionary Algorithms (EA) optimization method by keeping the standard deviation and the tolerance of the design parameters constant. In conclusion, the implemented EA optimization can reduce the standard deviation of the mass flow rate by approximate 51% and the new nominal designs at the valve seat edge breaks are obtained.

The hydraulic-controlled blowout preventer ball valve shearing mechanism is a critical tool for cutting operation strings and sealing high-pressure underground oil and gas emissions during emergencies in offshore completion operations. This study aims to address the challenges faced by existing tools in shearing operation strings. First, a finite element numerical model of the ball valve shearing mechanism was established based on the Johnson-Cook model, and its accuracy was validated through shearing experiments. Next, a single-factor analysis was performed on key structural parameters of the ball valve shearing mechanism, including the blade edge rounding radius, valve seat angle, and shearing clearance. Finally, the response surface methodology was applied to determine the optimal structural parameters of the ball valve shearing mechanism. The results showed that the shearing torque of the ball valve shearing mechanism initially decreases and then increases with variations in the blade edge rounding radius, shearing clearance, and valve seat angle. The optimal structural parameters of the ball valve shearing mechanism were determined to be a blade edge rounding radius of 1.89 mm, a valve seat angle of 32.06°, and a shearing clearance of 1.91 mm. Under these conditions, the peak shearing torque obtained from the response surface analysis was 12.68 kN·m, while the peak shearing torque calculated from the finite element numerical model was 13.02 kN·m, with a relative error of 2.62%. Compared to the original design’s peak shearing torque of 16.92 kN·m, this optimization reduced the shearing torque by 22.34%, significantly enhancing the performance of the mechanism.

A rotary sealing device that automatically compensates for wear is designed to address the issues of easy wear and the short service life of the rotary sealing device with automatic wear compensation in mining machinery. After the end face of the guide sleeve wears out, it still tightly adheres to the sealing valve seat under the pressure difference, achieving automatic wear compensation. Based on fluid-solid coupling technology, the structural strength of the rotary sealing device was checked. The influence of factors on the sealing performance of rotary sealing devices was studied using the control variable method. The results show that as the pressure of water increases, the leakage rate of the sealing device decreases, and after 30 MPa, the leakage rate is almost 0 mL/h. The temperature of the rotating sealing device increases with the increase of rotation speed or pressure, and the temperature is more affected by the rotation speed factor. The frictional torque increases with increasing pressure and is independent of rotational speed. Comprehensive analysis shows that the wear resistance and reliability level of the sealing guide sleeve material is PVDF>PEEK>PE>PA. This study designs a high-pressure automatic compensation wear rotary sealing device and selects the optimal sealing material, providing technical support for the application of high-pressure water jet in mining machinery.

The Military Academy has high vehicle mobility, particularly motorcycles that are intensively used as a means of transportation within the academy environment. High usage leads to wear and tear on engine components, especially the valve seat, which can affect fuel efficiency and engine power. This study aims to analyze the replacement material for the valve seat on a Honda CB 100 CC motorcycle through material composition testing, hardness testing, and microstructure analysis. The research results indicate that the original valve seat is made of an alloy steel containing chromium and a small amount of nickel, with characteristics similar to the XW-5 material produced by Krakatau Steel. The microstructure analysis reveals a dominance of ferrite and pearlite, which can lead to material brittleness at high temperatures. Therefore, selecting a material that is more heat- and wear-resistant is crucial in designing a replacement valve seat. This study is expected to provide a solution for maintaining and improving the efficiency of motorcycles at the Military Academy while addressing the issue of spare part shortages.

Abstract The European Spallation Source (ESS) is a neutron-scattering facility which will use a pulsed 2.0 GeV proton beam generated in the linear accelerator (LINAC) for releasing high-energy neutrons in the ESS target station. The 2K superconducting linac comprises 13 spoke and 30 elliptical cryomodules. The cryogenic distribution system (CDS) connects the cryogenic plant with the 43 cryomodules through a 400 meters long cryogenic multi-transfer, 43 valve boxes and an endbox. The CDS consists of 373 control valves in total. There are 8 and 10 control valves in each elliptical and spoke valve boxes, respectively, and 3 valves in the end box. The control valves are used for regulating or blocking the process helium flows. The seat tightness of the CDS valves is crucial especially for warming up individual cryomodules, which is required for potential short-term maintenance or repair activities in the cryomodule while keeping the others in cryogenic conditions. What is more, leaks over valve seats might cause moisture or ice formation on room temperature uninsulated pipes for warmup and cooldown valves or add heat load to the cryogenic system. Valve initialization and leak tightness tests were firstly performed with warm helium in the second half of 2022 before the first CDS cooldown. The tests revealed many leaks above the specified acceptable leak rate of 10-4 mbarl/s with several of them reaching even 102 mbar.l/s. The major bulk of those leaks were fixed before and after the 2nd CDS cooldown that followed in 2023. This paper describes the seat leak test method and results, as well as the possible causes of the observed leaks, the taken solutions for repairing the insufficiently tight valves and the prevention for valve seat leak.

Study of Thermal Stability of Phosphorus Bainitic Gray Cast Iron for Valve Seats of Internal Combustion Engines

Improvement of wear resistance for engine valve: Introducing cold upsetting treatment on valve seating face

Parametric design for the valve seat of a high-temperature and high-pressure valve inside wind tunnels

Targeting the issue of inconsistent fuel injection across multiple holes in high-pressure common rail injectors, this study integrates the spray momentum method with spray visualization techniques to conduct an in-depth experimental investigation into the liquid fuel injection and spray characteristics of each injector hole under varying injection pressures and pulse widths. The research findings indicate that under conditions of low injection pressure and narrow injection pulse width, the average volatility rate of cycle fuel injection quantity δ i , the difference coefficient of cycle fuel injection quantity σ ^ Q , the difference coefficient of spray penetration σ ^ L and the difference coefficient of spray equivalence ratio σ ^ φ of each injector hole are larger, and the inconsistency of the liquid fuel injection/spray is larger. With the increase in injection pressure or pulse width, fuel injection inconsistency decreases. However, at higher levels of injection pressure or pulse width, further increases have minimal impact on the fuel injection inconsistency across individual injection holes. The primary influence of injection pressure and pulse width on fuel injection inconsistency is through their effect on the movement of the needle valve. Under the conditions of injection pressure or injection pulse width where the needle valve cannot reach the maximum lift, the instability of the needle valve movement causes frequent changes in the flow area between the needle valve and the needle valve seat, resulting in greater injection inconsistency. Under the conditions of the injection pressure or injection pulse width that enables the needle valve to reach the maximum lift, the fuel injection inconsistency is determined by the structural parameters of the injection hole, and the fuel injection inconsistency is small in this state. By selecting an appropriate combination of injection pressure and pulse width, the fuel injection inconsistency of the injector can be minimized.

Abstract A detailed study is conducted on the high-temperature wear performance of valve seat rings with different Ni contents. The wear resistance of two types of contact pairs is studied through methods such as three-dimensional profile, wear amount, and wear morphology. Research has shown that the friction coefficients of both contact pairs gradually decrease with increasing temperature, while the wear amount of both contact pairs shows a trend of first decreasing and then increasing, and both have the lowest wear amount under 500? conditions. The wear performance of Inconel 751 material contact pairs is better at room temperature, but Pyromet 31 material contact pairs have stronger stability under high-temperature conditions. Therefore, Pyromet 31 material has better wear and wear resistance in high-temperature environments. Temperature can affect the hardness of materials, resulting in varying degrees of material softening, and also affect the formation rate of oxide films on wear surfaces. The rapid formation of oxide films is an important reason for the greater wear resistance of Pyromet 31 materials.

This article presents a comprehensive assessment of the effects of hydrogen additives on internal combustion engines' durability and operational reliability (ICEs). In the context of the global energy transition and the need for decarbonization of the transport sector, hydrogen is considered a highly promising supplemental fuel due to its fast flame speed, broad flammability limits, and environmentally benign combustion products. When used as an additive to conventional fuels such as gasoline or diesel, hydrogen has the potential to reduce pollutant emissions, improve fuel economy, and enhance engine thermal efficiency. The study integrates an in-depth review of the scientific literature with original experimental results obtained using a four-stroke diesel engine, in which hydrogen was introduced into the intake manifold at concentrations ranging from 5% to 20% by volume. The findings indicate that hydrogen enrichment enhances brake thermal efficiency (BTE) by up to 10% compared to baseline conditions. Moreover, a substantial reduction in carbon monoxide (CO) and hydrocarbon (HC) emissions was observed. However, the rise in combustion temperature led to additional thermal stress on engine components, particularly valve seats, cylinder head areas, and piston rings. Signs of hydrogen embrittlement were also recorded, and increased moisture content in lubricants, reaching up to 2%, which promoted corrosion of metallic elements. Despite these challenges, hydrogen-modified engines demonstrated stable performance throughout the 1000-hour test cycle. Nonetheless, maintenance intervals for critical components such as the valve train were reduced, underscoring the necessity of improved materials and lubricant formulations. It is concluded that hydrogen additives can provide an effective interim strategy for enhancing ICE performance, but further investigation into long-term mechanical and chemical impacts is essential.

Cavitation may quickly damage the surfaces of the valve core and valve seat, causing noise, and vibration problems. Different cavitation stages will affect the regulating valve's flow characteristics to different degrees. Flow rate is one of the basic parameters in a hydraulic system, which is innovatively used to evaluate the cavitation flow. By analyzing the deviation ratio K between actual and theoretical flow rate, cavitation flows are divided into four stages, and the dynamic behavior in different stages is discussed using a high-speed camera and image processing technology. When K is zero, it is defined as the no-cavitation stage. A slight increase in K is the incipient cavitation stage, whose K is within 2%. A rapid decrease in K is the critical cavitation stage, while a significant increase in K is the severe cavitation stage. In the incipient cavitation stage, bubbles are adhered to the valve orifice forming attached cavities. In the critical cavitation stage, attached cavities develop along the throat wall, with some bubbles detaching to form free cavities. This process is accompanied by high-frequency shedding and collapses, with a dominant frequency of 4266 Hz. In the severe cavitation stage, larger attached cavities are located at the throat, whose front edge of cavitation will fracture into large-scale cavitation clouds. Furthermore, this study proposed the cavitation intensity to elucidate the spatial distribution and density of cavitation flow, the cavitation change rate to highlight the disturbances and nonuniformities caused by cavitation bubbles, and the cavitation coefficient to evaluate the severity of cavitation. Additionally, there is a strong correlation between the growth rate of cavitation length L and the growth rate of flow rate Q in the regulating valve. Both the growth rate of L and Q increase in the critical cavitation stage and decrease in the severe cavitation stage.

The article discusses methods for restoring valve seats for the “valve-valve seat” connection using the example of the Honda K20A engine. The characteristics of the above connection, the reasons for its wear and the main signs of wear are presented. Specific parameters and recovery indicators are provided, such as grinding angles, width of the contact zone, permissible alignment deviations, as well as quality control methods. In conclusion, recommendations are presented for choosing the most rational restoration method depending on the degree of wear. The article is of a review nature, as a result of research conducted during the master's thesis.