High-pressure Supply Research Articles

ESO-based robust adaptive control for dual closed-loop fuel control system in aeroengine

To improve the flowrate control accuracy of fuel control system at high supply pressure and large flowrate working condition, this paper proposes a novel dual closed-loop control for fuel metering unit (FMU) to address issues related to unknown velocity, matched/unmatched disturbances, and parameter uncertainties. Firstly, for a comprehensive assessment in flowrate feedback method, a global sensitive analysis is utilized to research the effect ratio of factors affecting the discharge flowrate. Then, a novel dual closed-loop control is proposed, in which the outer loop is flowrate loop, and a novel extended-state-observer (ESO)-based robust adaptive control without velocity sensor is used as the internal displacement loop control. Specifically, ESO can effectively estimate the unknown velocity and unmatched disturbance, and the parameter estimations can be updated by the adaptive law determined only by spool displacement and reference signal. The novel robust control can address matched/unmatched disturbances and model uncertainties effectively. Through Lyapunov method, it follows that the novel ESO-based robust adaptive control can achieve asymptotic tracking performance when occurring time-invariant disturbances and bounded tracking performance when occurring time-varying disturbances. Comparative experiments verify the superiority of the proposed control, which provides a new method and glimpse for the advanced control strategy of aeroengine.

Justifying employee gatekeeping: A video-elicitation and comparative study on resolving the moral unease of hiring

Hiring is an act of evaluation that comes with much organizational and social responsibility, making it a morally sensitive situation. The way employee gatekeepers come to terms with their selections presents itself as an exemplary case to study the moral dimension of organizational life. Relying on a pragmatist perspective and an economies of worth framework, this article uncovers how employers experience moral uncertainty and justify their choices. Through a comparison of gatekeeping in two employment fields, this study covers new ground on how decision logics and regimes of valuation play out and can be structurally conditioned. Through in-depth interviews, combined with a ranking exercise based on video-elicitation, with recruiters and hiring managers from the corporate (n: 23) and cultural (n: 17) fields in the Netherlands, this paper explores how evaluation processes and selections are justified. The interviews show that a sense of moral unease is common among gatekeepers, but much more prevalent among corporate rather than cultural gatekeepers. Larger organizational size, high market pressure and lower supply of candidates does not translate into moral sterility for corporate gatekeepers. Second, the study reveals that a connexionist logic enters as a powerful justificatory regime, transforming candidate selection procedures into test of confession.

Multi-objective design optimization of hydride hydrogen storage reactor structured with finned helical tubes based on energetic and economic analyses

Hydride-based systems are a potential alternative to hydrogen storage technologies due to their simple structure and ambient operating conditions. The optimization of hydride reactor design factors is highly correlated to the targeted application. This research focuses on optimizing the thermal-static performance of LaNi5-holding helically coiled hydride reactors employing combined response surface methodology, computational modeling, and a desirability approach. The structural geometric design optimization factors include the diameter of the helical tubes and shell, the number of helical tubes, the pitch, and the distance between two adjacent helical tubes. Responses comprise a dimensionless characteristic response – weight ratio (static performance) and 90 % absorption time with maximal heat extraction rate (thermal performance). The quadratic regression model outperformed the linear regression models in terms of accuracy and reliability, effectively reducing the number of computational runs by 83 % compared to the standard parametric study-based technique. Combinatorically assessing the weight ratio and thermal power to be set to the maximum at the quickest absorption time resulted in selecting the best helical reactor design. The optimal base case was further improvised by integrating fins, which were optimized using the proposed methodology. The optimal base case and finned helical reactor subjected to sensitivity analysis revealed that the latter exhibited an average 18 % fall in complete saturation time and a 16 % rise in thermal power despite the 5.66 % loss in weight ratio. The Levelized cost of hydrogen storage was substantially reduced by 18–23 % when operated at higher supply pressures and fluid inlet temperatures. Besides, when the price of the finned reactor to its base case ratio was cut from 1.5 to 1.1, the optimized finned reactor turned economical. Furthermore, the outcomes of a systematic literature comparative study demonstrated that the constructed finned helical reactor was superior to its equivalent, accounting for a 60–75 % drop in 90 % saturation time. As an upshot, this study aids the researchers in designing accurate and apt objective-based hydride reactors using the proposed statistical method: coupled quadratic regression-thermal modeling-desirability approach-based design optimization.

Research on the influence of a micro-groove-orifice structure and its layout form on the static characteristics of aerostatic journal bearings under a high gas supply pressure

To solve the problems of a low gas supply pressure and low load capacity of traditional orifice-compensated aerostatic journal bearings (OCAJBs), this paper presents the design of a double-row gas supply micro-groove-orifice aerostatic journal bearing (MGOAJB). By establishing new governing equations and introducing the SST k- ω turbulence model, the influence of the micro-groove-orifice (MGO) structure and its layout form on the static characteristics of aerostatic journal bearings under a high gas supply pressure are studied. It is found that under high gas supply pressure, the MGO structure can significantly improve the load capacity and stiffness and reduce the gas consumption of the MGOAJB compared with the OCAJB. With additional MGO structures in the eccentric direction of the spindle, the load capacity and stiffness of the bearing increase substantially, and the gas flow also increases. The layout direction of the MGO has a prominent influence on the static characteristics of the MGOAJB. Axial MGOs have a higher load capacity and stiffness and lower gas flow. The accuracy of the simulation method is verified by experiments. This study provides a theoretical basis and method for the design of aerostatic journal bearings under a high gas supply pressure.

Pseudo-chromosome-length genome assembly for a deep-sea eel Ilyophis brunneus sheds light on the deep-sea adaptation.

High hydrostatic pressure, low temperature, and scarce food supply are the major factors that limit the survival of vertebrates in extreme deep-sea environments. Here, we constructed a high-quality genome of the deep-sea Muddy arrowtooth eel (MAE, Ilyophis brunneus, captured below a depth of 3,500 m) by using Illumina, PacBio, and Hi-C sequencing. We compare it against those of shallow-water eel and other outgroups to explore the genetic basis that underlies the adaptive evolution to deep-sea biomes. The MAE genome was estimated to be 1.47 Gb and assembled into 14 pseudo-chromosomes. Phylogenetic analyses indicated that MAE diverged from its closely related shallow-sea species, European eel, ∼111.9 Mya and experienced a rapid evolution. The genome evolutionary analyses primarily revealed the following: (i) under high hydrostatic pressure, the positively selected gene TUBGCP3 and the expanded family MLC1 may improve the cytoskeleton stability; ACOX1 may enhance the fluidity of cell membrane and maintain transport activity; the expansion of ABCC12 gene family may enhance the integrity of DNA; (ii) positively selected HARS likely maintain the transcription ability at low temperatures; and (iii) energy metabolism under a food-limited environment may be increased by expanded and positively selected genes in AMPK and mTOR signaling pathways.

Morphological and molecular evolution of hadal amphipod's eggs provides insights into embryogenesis under high hydrostatic pressure.

Hadal zones are unique habitats characterized by high hydrostatic pressure (HHP) and scarce food supplies. The ability of eggs of species dwelling in hadal zones to develop into normal embryo under high hydrostatic pressure is an important evolutionary and developmental trait. However, the mechanisms underlying the development of eggs of hadal-dwelling species remain unknown due to the difficulty of sampling ovigerous females. Here, morphological and transcriptome analyses of eggs of the “supergiant” amphipod Alicella gigantea collected from the New Britain Trench were conducted. The morphology of A. gigantea eggs, including size, was assessed and the ultrastructure of the eggshell was investigated by scanning electron microscopy. Transcriptome sequencing and molecular adaptive evolution analysis of A. gigantea eggs showed that, as compared with shallow-water Gammarus species, genes exhibiting accelerated evolution and the positively selected genes were mostly related to pathways associated with “mitosis” and “chitin-based embryonic cuticle biosynthetic process”, suggesting that “normal mitosis maintenance” and “cuticle development and protection” are the two main adaptation strategies for survival of eggs in hadal environments. In addition, the concentration of trimethylamine oxide (TMAO), an important osmotic regulator, was significantly higher in the eggs of hadal amphipods as compared to those of shallow-water species, which might promote the eggs’ adaptation abilities. Morphological identification, evolutionary analysis, and the trimethylamine oxide concentration of A. gigantea eggs will facilitate a comprehensive overview of the piezophilic adaptation of embryos in hadal environments and provide a strategy to analyze embryogenesis under high hydrostatic pressure.

Research on the influence of supersonic phenomena on the gas film flow field of micron-groove-orifice aerostatic journal bearings under high gas supply pressure

To solve the problem of performance degradation caused by supersonic phenomena under high gas supply pressures in orifice-compensated aerostatic journal bearings (OCAJBs), a double-row gas supply micron-groove-orifice aerostatic journal bearing (MGOAJB) is designed, and the SST k- ω turbulence model is used to analyze the influences of the supersonic phenomena on the gas film flow field under different gas supply pressures, gas film thicknesses and orifice diameters. Compared with traditional OCAJBs, under high gas supply pressure, supersonic phenomena occur near the gas film inlet in both the MGOAJB and the OCAJB. The Mach number, maximum pressure, temperature and Reynolds number of the OCAJB are higher than those of the MGOAJB, but the MGOAJB has a more stable gas film pressure due to pressure equalization. As the gas film thickness of the MGOAJB increases, the Mach number, Reynolds number and temperature near the gas film inlet increase, but the pressure decreases, the recovery of the pressure and temperature becomes more obvious when the gas velocity drops to a subsonic speed. With increases in the MGOAJB orifice diameter, the pressure, temperature and Reynolds number increase, the Mach number decreases, and the recovery of the pressure and gas temperature becomes more obvious.

Trimethylamine N-Oxide (TMAO) and Trimethylamine (TMA) Determinations of Two Hadal Amphipods

Hadal trenches are a unique habitat with high hydrostatic pressure, low temperature and scarce food supplies. Amphipods are the dominant scavenging metazoan species in this ecosystem. Trimethylamine (TMA) and trimethylamine oxide (TMAO) have been shown to play important roles in regulating osmotic pressure in mammals, hadal dwellers and even microbes. However, the distributions of TMAO and TMA concentrations of hadal animals among different tissues have not been reported so far. Here, the TMAO and TMA contents of eight tissues of two hadal amphipods, Hirondellea gigas and Alicella gigantea from the Mariana Trench and the New Britain Trench, were detected by using the ultrahigh performance liquid chromatography–mass spectrometry (UPLC-MS/MS) method. Compared with the shallow water Decapoda, Penaeus vannamei, the hadal amphipods possessed significantly higher TMAO concentrations and a similar level of TMA in all the detected tissues. A higher level of TMAO was detected in the external organs (such as the eye and exoskeleton) for both of the two hadal amphipods, which indicated that the TMAO concentration was not evenly distributed, although the same hydrostatic pressure existed in the outer and internal organs. Moreover, a strong positive correlation was found between the concentrations of TMAO and TMA in the two hadal amphipods. In addition, evolutionary analysis regarding FMO3, the enzyme to convert TMA into TMAO, was also conducted. Three positive selected sites in the conserved region and two specific mutation sites in two conserved motifs were found in the A. gigantea FMO3 gene. Combined together, this study supports the important role of TMAO for the environmental adaptability of hadal amphipods and speculates on the molecular evolution and protein structure of FMO3 in hadal species.

Research on the effect of micron-groove orifices on the static characteristics of aerostatic journal bearings under high gas supply pressures based on the SST k-ω turbulence model

To improve the static characteristics of orifice-compensated aerostatic journal bearings (OCAJBs) under high gas supply pressures, governing equations considering inertial forces are established based on the shear stress transport (SST) k- ω turbulence model, and a double-row gas supply micron-groove orifice aerostatic journal bearing (MGOAJB) is designed. The influences of the structural parameters of the micron-groove orifice (MGO), such as the groove cross-sectional shape, dimensional parameters and layout, on the static characteristics under high gas supply pressures are studied. The SST k- ω turbulence model can accurately simulate the pressure distribution of a gas film flow field under high gas supply pressures, and the MGO can effectively improve static bearing characteristics such as the load capacity and stiffness. The influences of the groove cross-sectional shape, groove depth, and groove width of the MGO are not significant, but the groove length, orifice diameter, and MGO layout have obvious impacts on the load capacity and stiffness of a bearing. Structural parameters should be reasonably selected in the bearing design process.

Tap Water Quality Degradation in an Intermittent Water Supply Area

Decentralized tap water systems are an important drinking water source worldwide. A good quality, high-pressure continuous water supply (CWS) is always the target of any urban settlement. However, tap water in some areas are reported with deteriorated water quality even though treated well before supplying. Such deterioration of tap water quality is reported widely from areas with low water availability and in economically poor countries where water are supplied intermittently (IWS). This study focuses in identifying tap water quality in IWS and causes of water quality degradation using nitrate-nitrogen (NO3-N) as an indicator and stable isotopes of hydrogen (δD) as tracer. Nine water reservoirs and ninety municipal tap water (ten per reservoir) samples were collected during the wet (June–September) and dry (November–February) seasons in the Kathmandu Valley (KV), Nepal. Ten percent of the tap water samples exhibited higher NO3-N than those of their respective reservoirs during the wet season, while 16% exhibited higher concentrations during the dry season. Similarly, the isotopic signatures of tap water exhibited 3% and 23% higher concentrations than those of their respective reservoirs during the wet and dry seasons, respectively. Coupling analysis between NO3-N and δD demonstrates close connection of groundwater and tap water. The results indicate groundwater intrusion as the primary component in controlling tap water quality variations within the same distribution networks during IWS. Meanwhile, the obtained results also indicate probable areas of intrusion in the KV as well as usefulness of δD as a tool in the assessment of tap water systems.

A mild and selective Cu(II) salts-catalyzed reduction of nitro, azo, azoxy, N-aryl hydroxylamine, nitroso, acid halide, ester, and azide compounds using hydrogen surrogacy of sodium borohydride

The first mild, in situ, single-pot, high-yielding well-screened copper (II) salt-based catalyst system utilizing the hydrogen surrogacy of sodium borohydride for selective hydrogenation of a broad range of nitro substrates into the corresponding amine under habitancy of water or methanol like green solvents have been described. Moreover, this catalytic system can also activate various functional groups for hydride reduction within prompted time, with low catalyst-loading, without any requirement of high pressure or molecular hydrogen supply. Notably, this system explores a great potential to substitute expensive traditional hydrogenation methodologies and thus offers a greener and simple hydrogenative strategy in the field of organic synthesis.

Flow field of impinging sweeping jets

Sweeping jets are oscillating jets generated by fluidic oscillators, i.e., devices designed to produce an oscillation of the flow without the use of any moving parts (Raghu, 2013). A typical configuration of such devices consists of an expansion chamber connected to a high-pressure supply via a converging nozzle and provided with feedback channels. The oscillating motion in the expansion chamber is triggered by an inherent flow instability and sustained by the flow rate across the feedback channels. Recently, sweeping jets have been studied in flow control applications for noise reduction, separation and circulation control over airfoils, control of resonant cavity oscillations and deflection of jets. The advantageous features of fluidic actuators, among which are the wide range of operating frequencies (up to kHz with meso-scale) and the distributed momentum addition, have also stimulated an increasing interest in their application to electronics cooling. Several recent studies on the convective heat transfer from impinging sweeping jets (e.g., Hossain et al., 2018; Park et al., 2018) have shown that, compared to conventional round jets, they offer higher cooling rates with better uniformity at least for small jet-to-plate spacings.

Numerical analysis on the performance characteristics of a new gas journal bearing by using finite difference method

This paper proposes a novel gas journal bearing in which orifices are different in diameter and distribute unevenly. Finite Difference Method (FDM) combined with Linear Perturbation Method (LPM) is used to solve the unsteady-state Reynolds equation of the flow field in the bearing clearance. Moreover, four types of bearing structures are used to discuss the effects of orifices different in diameter and uneven distribution on the bearing performance. The results demonstrate that the new bearing has better static and dynamic performances compared with those of traditional bearing in which orifices are equal in diameter and distribute evenly. Moreover, thin gas film thickness, high supply pressure, and large eccentricity ratio are hopeful for improving load capacity of the new bearing. Furthermore, the stability of the novel bearing is improved if eccentricity ratio is 0.25–0.3.

Aerotunelska verifikacija efekata isticanja mlaza na aerodinamičke karakteristike osnosimetričnog projektila

Experimental verification of base-bleed effects on aerodynamic characteristics for the supersonic flight stages was requested during the development of an axi-symmetric projectile. The experimental setup for testing base-bleed configurations of the projectile was designed, built and tested in the T-38 trisonic blowdown wind tunnel of the Military Technical Institute (VTI), Belgrade. Gas-generator was formed from a simple chamber with a single manifold pneumatically connected to a high-pressure air supply. Wind tunnel tests comprised measurement of aerodynamic forces and moments of the projectile with active base-bleed. Flow visualization was performed using the Schlieren method. It was of interest to verify the base drag reduction in the wind tunnel tests and to compare it with numerical predictions. In addition, the experience gained during these tests has been found to be helpful in the design of the future similar wind tunnel setups

Economic and ecological evaluation of high-pressure cutting fluid supply in milling of Ti-6Al-4V

The high-pressure cutting fluid supply has proven its technological, economic and ecological benefits in turning. In milling, there is fundamental knowledge regarding the impact of the focused high-pressure supply on tool wear and chip removal. However, for multiple row shell milling cutters, investigations regarding the feasibility and the effects of the changed boundary conditions for the application of high-pressure are lacking. In this work, investigations for machining of aerospace structural parts of Ti-6Al-4V, including an economic and ecological evaluation between conventional and high-pressure cutting fluid machining, are presented. A case study verified the feasibility and revealed economic and ecological benefits.

Evaluating metal constraints for photovoltaics: Perspectives from China’s PV development

Chinese PV industry can be expected to grow rapidly of until 2050, driven by ongoing decarbonization of the energy mix. Such large-scale deployments generate significant increases in metal demand that may induce resource dilemmas. In this study, dynamic material flow analysis is combined with scenario analysis to estimate future metal demand from Chinese PV industry and complemented by a supply risk assessment. It is found that the maximum annual copper and silver demand up to 2050 equals 79.6% and 58.5% of China’s annual production in 2019. Similarly, the baseline scenario projects maximum annual demand of Tellurium and Indium corresponding to 598.1% and 161.8% of China’s annual production in 2019. Cumulative base metal demand by 2050 for China’s PV sector is 17.3–22.8 times that of in 2018, while cumulative silver demand increases by 4.5–6 times from 2018 to 2050. In the baseline scenario, cumulative byproduct metal demand by 2050 is 14–27.3 times larger than in 2018. High annual and cumulative supply pressures indicate not only the general scarcity of base, precious, and byproduct metals but also highlights the importance of building stable trade relationships for future PV developments in China. Two different measures are identified and assessed for reducing short- and long-term supply risks. Prolonging the lifetime from 25 to 30 years can achieve a cumulative metal conservation of 6.7–24.2%, while shorter lifetime will give rise to secondary supply if recycling technologies are implemented. A clean energy shift indicates that metal availability will become an important perspective for assessing energy security, implying that resource constraints should be considered in different planning levels for renewable energy developments. Strong interconnections between energy and metal supply chains indicate that coordination and holistic nexus views are required for achieving simultaneous sustainability in both systems.

Theoretical and Experimental Studies of a Digital Flow Booster Operating at High Pressures and Flow Rates

The switched inertance hydraulic converter (SIHC) is a new technology providing an alternative to conventional proportional or servo-valve-controlled systems in the area of fluid power. SIHCs can adjust or control flow and pressure by means of using digital control signals that do not rely on throttling the flow and dissipation of power, and provide hydraulic systems with high-energy efficiency, flexible control, and insensitivity to contamination. In this article, the analytical models of an SIHC in a three-port flow-booster configuration were used and validated at high operating pressure, with the low- and high-pressure supplies of 30 and 90 bar and a high delivery flow rate of 21 L/min. The system dynamics, flow responses, and power consumption were investigated and theoretically and experimentally validated. Results were compared to previous results achieved using low operating pressures, where low- and high-pressure supplies were 20 and 30 bar, and the delivery flow rate was 7 L/min. We concluded that the analytical models could effectively predict SIHC performance, and higher operating pressures and flow rates could result in system uncertainties that need to be understood well. As high operating pressure or flow rate is a common requirement in hydraulic systems, this constitutes an important contribution to the development of newly switched inertance hydraulic converters and the improvement of fluid-power energy efficiency.

Risk Factors in a Process of Gas Supply Pipeline Construcion

The paper applies to the risk management in the specialized construction by the example of construction of a high-pressure gas supply pipeline. The specific character of the construction project has an impact on the scope and types of risks which may occur and adversely affect the outcome of the project. The paper aims to indicate the groups of technological tasks which need to be carried out when constructing a gas supply pipeline, the associated factor risks and the quality control method as a tool of mitigating the level of risk.

Pressure surges during filling of partially empty undulating pipelines

ABSTRACT Transients generated by expulsion of air pockets in water pipelines represent a key issue in the management of water systems. Severe pressure surges may arise, with detrimental effects on pipelines, valves and other devices. To analyze the transient and predict the resulting pressure surge, both theoretical and experimental studies have been developed in the literature. However, most studies consider horizontal or vertical pipelines, whereas the actual profile in the real field environment is a sequence of ascending and descending pipes. Consequently, this paper summarizes laboratory experiments carried out on an undulating pipeline, with an orifice fitted at the high point to simulate an air release valve. In the experiments, the orifice diameter, the supply pressure and the air volume entrapped in the descending pipe were varied. In almost all the runs, the peak pressure was achieved during the mass oscillation transient. Water hammer only occurs because of the expulsion of air bubbles within the water column, but generally the effect on the transient is fairly negligible. Results also showed that pressure surges decrease upon increasing the orifice diameter, except for high supply pressure and small-entrapped volume, for which an intermediate ‘critical’ orifice diameter can be identified.

Nonlinear dynamic analysis of a rotor-bearing system with porous tilting pad bearing support

Porous tilting pad bearings (PTPBs) show a potential for using in high-speed, high precision rotating machinery that requires high bearing stiffness and good stability. In this study, the nonlinear characteristics of a rotor supported on PTPBs are investigated. The Darcy equations and the modified Reynolds equations are adopted to establish the gas flow model in porous materials and gas film region, respectively. The pad motions and rotor motions are also included in the numerical nonlinear model. The advantages of PTPBs over tilting pad journal bearings are discussed. PTPBs with externally pressurized gas can avoid friction during startup and shutdown, improve the load capacity at low rotational speeds, and effectively suppress subsynchronous vibrations at high rotational speeds. The nonlinear characteristics of the rotor-bearing system with various bearing parameters, such as supply pressure ratio, nominal bearing clearance, pad tilting and radial stiffness, are analyzed. Poincare maps, predicted rotor orbit and bifurcation diagrams are used. High supply pressure ratio and small nominal bearing clearance can significantly decrease the orbit size and increase the critical speed. Low tilting and high radial stiffness can improve system stability. This study reveals the complex nonlinear characteristics of the system and provides guidance for designing PTPBs for using in high-speed rotating machinery.