The paper describes the new pressurization system for the upper stage of launch vehicles and spacecraft and the flight test results of the vehicle which conform to the design of the system.
Advanced high strength steels are the group of material with high strength and good formability, because high strength lesser gauge thickness can be used without compromising the function of component. In terms of eco...Advanced high strength steels are the group of material with high strength and good formability, because high strength lesser gauge thickness can be used without compromising the function of component. In terms of economic forming process, hydroforming is the manufacturing option which uses a fluid medium to form a component by using high internal pressure. This process gained steep interest in the automotive and aerospace industries because of its many advantages such as part consolidation, good quality of the formed part etc. The main advantage is that the uniform pressure can be transferred to whole projected part at the same time. Low pressure tube hydroforming considered an inexpensive option for forming these advanced high strength steel. This paper investigates the pressurization system used during the low pressure tube hydroforming cycle. It is observed that the usage of ramp pressure cycle during forming the part from low pressure tube hydroforming results in lesser die holding force. Also, the stress, strain and thickness distribution of the part during low pressure tube hydroforming are critically analysed.展开更多
The reliable and intelligent propulsion pressurization system is one of the key technologies of new Chinese generation launch vehicles; a high reliability design is an important guarantee for the success of launching....The reliable and intelligent propulsion pressurization system is one of the key technologies of new Chinese generation launch vehicles; a high reliability design is an important guarantee for the success of launching. This paper analyzes the domestic and overseas liquid launch vehicles in the area of propulsion pressurization systems, based on comprehensive analysis, demonstrating the reliable and intelligent propulsion pressurization system of the Long March 7(Simplified as LM-7) has been raised. By applying a full chain redundancy design, setting proper pressure control bandwidth and control mode reconstruction under extreme fault conditions, the reliability and adaptability of the propulsion pressurization system has enhanced significantly. In addition, the complete system has been verified by the first two flights of LM-7.展开更多
A new compact pressurization control system of the low pressure casting machine for crucible pressure casting has been developed. It is especially designed for the production of high-quality aluminum or magnesium allo...A new compact pressurization control system of the low pressure casting machine for crucible pressure casting has been developed. It is especially designed for the production of high-quality aluminum or magnesium alloy parts with low input cost. This machine with such a system has the virtue of economical and compact, and combines the Fuzzy-PID technology and achieves accuracies of ±2.5 mbar. At present, this machine has been adopted by several users in China for the production of aluminum alloy castings with high property requirements. Furthermore, for magnesium alloy castings, this machine can be used with the gas protect unit.展开更多
A new gas preparation system(GasPS-RCS)is proposed to solve two tasks:(A)to heat helium gas for tank pressurization;(B)to prepare gas for the Launch Vehicle(LV)Reactive Control System(RCS)at the LV orientation and sta...A new gas preparation system(GasPS-RCS)is proposed to solve two tasks:(A)to heat helium gas for tank pressurization;(B)to prepare gas for the Launch Vehicle(LV)Reactive Control System(RCS)at the LV orientation and stabilization sections of the LV on passive parts of the flight trajectory,to provide conditions for launching the Liquid Rocket Engine(LRE).The system includes a gas generator based on hydrogen peroxide,a separator for water separation,heat exchangers independent of the LRE,and gas-jet nozzles.The proposed new system allowed to reduce the length of pressurizing gas lines and reduce the increased helium gas consumption during the heat exchanger warm-up interval of the LRE during its launch.A special advantage of the proposed system is the possibility of ground testing of heat exchangers without an operating LRE.A mathematical model based on the first law of thermodynamics was used to perform a comparative analysis of GasPS-RCS with traditional pressurization and RCS systems.To validate the mathematical model,the experimental studies of helium pressurizing of a liquid nitrogen tank were conducted.The results show that the deviation of experimental and calculated values for pressure is 1.1%and for temperature up to 2%.According to the results of comparative analysis,the GasPS-RCS is 259 kg lighter for the first stage and 80 kg lighter for the second stage of the LV.展开更多
The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommod...The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.展开更多
In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-b...In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-based alloy(typically pure lead or lead-bismuth eutectic(LBE))is used as the coolant.To clarify the pressure build-up characteristics under water-jet injection,this study conducted several experiments by injecting pressurized water into a molten LBE pool at Sun Yat-sen University.To obtain a further understanding,several new experimental parameters were adopted,including the melt temperature,water subcooling,injection pressure,injection duration,and nozzle diameter.Through detailed analyses,it was found that the pressure and temperature during the water-melt interaction exhibited a consistent variation trend with our previous water-droplet injection mode LBE experiment.Similarly,the existence of a steam explosion was confirmed,which typically results in a much stronger pressure build-up.For the non-explosion cases,increasing the injection pressure,melt-pool temperature,nozzle diameter,and water subcooling promoted pressure build-up in the melt pool.However,a limited enhancement effect was observed when increasing the injection duration,which may be owing to the continually rising pressure in the interaction vessel or the isolation effect of the generated steam cavity.Regardless of whether a steam explosion occurred,the calculated mechanical and kinetic energy conversion efficiencies of the melt were relatively small(not exceeding 4.1%and 0.7%,respectively).Moreover,the range of the conversion efficiency was similar to that of previous water-droplet experiments,although the upper limit of the jet mode was slightly lower.展开更多
BACKGROUND Acute respiratory distress syndrome(ARDS)is a critical condition characterized by acute hypoxemia,non-cardiogenic pulmonary edema,and decreased lung compliance.The Berlin definition,updated in 2012,classifi...BACKGROUND Acute respiratory distress syndrome(ARDS)is a critical condition characterized by acute hypoxemia,non-cardiogenic pulmonary edema,and decreased lung compliance.The Berlin definition,updated in 2012,classifies ARDS severity based on the partial pressure of arterial oxygen/fractional inspired oxygen fraction ratio.Despite various treatment strategies,ARDS remains a significant public health concern with high mortality rates.AIM To evaluate the implications of driving pressure(DP)in ARDS management and its potential as a protective lung strategy.METHODS We conducted a systematic review using databases including EbscoHost,MEDLINE,CINAHL,PubMed,and Google Scholar.The search was limited to articles published between January 2015 and September 2024.Twenty-three peer-reviewed articles were selected based on inclusion criteria focusing on adult ARDS patients undergoing mechanical ventilation and DP strategies.The literature review was conducted and reported according to PRISMA 2020 guidelines.RESULTS DP,the difference between plateau pressure and positive end-expiratory pressure,is crucial in ARDS management.Studies indicate that lower DP levels are significantly associated with improved survival rates in ARDS patients.DP is a better predictor of mortality than tidal volume or positive end-expiratory pressure alone.Adjusting DP by optimizing lung compliance and minimizing overdistension and collapse can reduce ventilator-induced lung injury.CONCLUSION DP is a valuable parameter in ARDS management,offering a more precise measure of lung stress and strain than traditional metrics.Implementing DP as a threshold for safety can enhance protective ventilation strategies,po-tentially reducing mortality in ARDS patients.Further research is needed to refine DP measurement techniques and validate its clinical application in diverse patient populations.展开更多
Beijing Aerospace System Engineering Institute of China Academy of Launch Vehicle Technology (CALT) declared recently that theinstitute has set up a laboratory whichwould operate a newly
In order to address the current inability of screen printing to monitor printing pressure online,an online printing pressure monitoring system applied to screen printing machines was designed in this study.In this stu...In order to address the current inability of screen printing to monitor printing pressure online,an online printing pressure monitoring system applied to screen printing machines was designed in this study.In this study,the consistency of printed electrodes was measured by using a confocal microscope and the pressure distribution detected by online pressure monitoring system was compared to investigate the relationship.The results demonstrated the relationship between printing pressure and the consistency of printed electrodes.As printing pressure increases,the ink layer at the corresponding position becomes thicker and that higher printing pressure enhances the consistency of the printed electrodes.The experiment confirms the feasibility of the online pressure monitoring system,which aids in predicting and controlling the consistency of printed electrodes,thereby improving their performance.展开更多
Objective: To identify the principal factors associated with the occurrence and development of medical device-related pressure injuries (MDRPI) in adults admitted to hospitals. MDRPI, a peculiar subtype of pressure in...Objective: To identify the principal factors associated with the occurrence and development of medical device-related pressure injuries (MDRPI) in adults admitted to hospitals. MDRPI, a peculiar subtype of pressure injuries (PI), result from the pression exerted by devices (or their fixation systems) applied for diagnostic and therapeutic purposes. MDRPI represent a serious problem for patients and healthcare systems. Understanding potential risk factors is an important step in implementing effective interventions. Methods: In this study, we will perform a systematic review;if possible, also a meta-analysis will be performed. The review will follow the preferred reporting items for systematic reviews and meta-analyses (PRISMA) reporting guidelines for systematic reviews. A rigorous literature search will be conducted both in electronic databases (Medline/PubMed, Embase, CINAHL, Web of Science, Scopus, Cochrane Library) to identify studies published since 2000 and in gray literature for unpublished studies. Pairs of researchers will identify relevant evidence, extract data, and assess risk of bias independently in each eligible study. Factors associated with the occurrence of MDRPI are considered the primary outcome. Secondary outcomes are prevalence and incidence of MDRPI, length of hospital stay, infections, and death. The evidence will be synthesized using the GRADE methodology. Results: Results are not currently available as this is a protocol for a systematic review. Conclusions: This systematic review will identify evidence on risk factors for developing MDRPI. We are confident that the results of this review will help to improve clinical practice and guide future research.展开更多
Coastal tourism holds substantial development potential.However,coastal ecosystems are affected by tourism development,which limits the supply of ecosystem services(ES).This study aims to conduct a systematic literatu...Coastal tourism holds substantial development potential.However,coastal ecosystems are affected by tourism development,which limits the supply of ecosystem services(ES).This study aims to conduct a systematic literature review on the impacts of tourism on coastal and marine ES using the Preferred Reporting Items for Systematic Reviews and Meta-alpha Methods.We initially identified 640 studies by searching titles,abstracts,and keywords.After screening,only 50 studies met the criteria for inclusion in the review.The results showed a significant increase in publications between 2011 and 2023.Most studies were conducted in Europe,Asia,and North and Central America.The most used ES classifications were MEA and CICES.Most studies concentrated on the ES supply dimension(43 studies;86%).Cultural ES(47 studies;94%)were researched more than provisioning(28 studies;56%)and regulating&maintenance(29 studies;58%)sections.Regarding cultural ES,most studies were focused on“Physical and experiential interactions with the natural environment”(34 studies;68%)and on provisioning ES on“Wild animals(terrestrial and aquatic)for nutrition,materials or energy”(18 studies;36%).Quantitative and mixed methods were the most used in the reviewed studies.Most studies identified pressures from“Tourism,urbanisation,and population increase”(27 studies;54%)and focused on“Integrative/common management strategies”(20 studies;40%).Only a few of the studies’results have been validated by external data(10 studies;20%).This study provides an overview of the most assessed marine and coastal ES,where studies are needed with more comprehensive geographic coverage.展开更多
This research aims to understand the causes of fraud through the approach of the Fraud Triangle Theory,which includes three main factors:pressure,opportunity,rationalization.By using the Systematic Literature Review m...This research aims to understand the causes of fraud through the approach of the Fraud Triangle Theory,which includes three main factors:pressure,opportunity,rationalization.By using the Systematic Literature Review method from various relevant international journals,it analyzed systematically to identify patterns,trends,and theoretical contributions to efforts in detecting and preventing fraud.The results of this study show that the three factors in the Fraud Triangle Theory significantly contribute to the occurrence of fraud.Opportunity as the most dominant factor is caused by weak internal control systems and lack of oversight.In addition,economic pressure,and a permissive organizational environment,as well as the rationalization processes by individuals,also increase the tendency for a person to commit fraud.These findings emphasize the need for a comprehensive approach in fraud prevention strategies,through ethical values,the establishment of an organizational culture with integrity,and the implementation of more effective internal control and oversight.展开更多
The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb_(7)Ti,which is the only dynamically stab...The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb_(7)Ti,which is the only dynamically stable ordered Nb-Ti compound under ambient pressure.Extensive first-principles calculations have provided insights into the electronic structure,bonding and superconducting properties of Nb_(7)Ti.The superconducting transition temperature(T_(c))for Nb_(7)Ti at ambient pressure is estimated within the framework of BCS theory to be about 17.5 K,which is significantly higher—nearly double—that of the widely utilized NbTi alloy.Furthermore,the results unveil that the high T_(c) is mainly attributed to the unique ordered lattice along with the strong electron-phonon coupling driven by interatomic interactions at mid-frequency and phonon softening induced by low-frequency Fermi surface nesting.Valuable insights are provided for the subsequent synthesis of application-oriented superconductors at low pressure.展开更多
Objective:To systematically evaluate the effectiveness of mobile health(mHealth)interventions on self-management and blood pressure(BP)control in patients with hypertension and to provide recommendations for the clini...Objective:To systematically evaluate the effectiveness of mobile health(mHealth)interventions on self-management and blood pressure(BP)control in patients with hypertension and to provide recommendations for the clinic and future research.Methods:Databases including Embase,Cochrane Library,CINAHL,CNKI,SinoMed,Wanfang,and Weipu were searched to collect systematic reviews(SRs)and meta-analyses on mHealth interventions for hypertension management.Two researchers independently screened the articles and extracted data,and the Assessment of Multiple Systematic Reviews(AMSTAR 2)was used to evaluate the methodological quality of the included reviews.Results:A total of 11 SRs were included:1 review was rated as high quality,3 as low quality,and 7 as critically low quality.The mobile phone was the most common intervention type,followed by the internet.Seven reviews performed meta-analyses and showed that mHealth was associated with a significant reduction in systolic blood pressure(SBP),from 2.28 mmHg(95%CI-3.90 to-0.66;I^(2)=40%)to 14.77 mmHg(95%CI 11.76-17.77;I^(2)=89.7%),and diastolic blood pressure(DBP),from 1.50 mmHg(95%CI-2.20 to-0.08;I^(2)=62%)to 8.17 mmHg(95%CI 5.67-10.67;I^(2)=86%).Self-management behaviors included medication adherence(MA),diet,smoking,alcohol drinking,physical activity,and BP monitoring.There were inconsistent results on the effectiveness of mHealth interventions.Conclusions:mHealth interventions can improve BP control,MA,diet,and smoking in patients with hypertension,but the evidence for the efficacy of mHealth on physical activity and alcohol drinking improvement is limited.The methodological quality of existing SRs on the management of BP in patients with hypertension was relatively low,and more well-designed SRs or meta-analyses were needed to provide more evidence.mHealth interventions are useful for improving BP control of patients with hypertension.展开更多
To date,many previous studies have been proposed for driver authentication;however,these solutions have many shortcomings and are still far from practical for real-world applications.In this paper,we tackle the shortc...To date,many previous studies have been proposed for driver authentication;however,these solutions have many shortcomings and are still far from practical for real-world applications.In this paper,we tackle the shortcomings of the existing solutions and reach toward proposing a lightweight and practical authentication system,dubbed DriveMe,for identifying drivers on cars.Our novelty aspects are 1⃝Lightweight scheme that depends only on a single sensor data(i.e.,pressure readings)attached to the driver’s seat and belt.2⃝Practical evaluation in which one-class authentication models are trained from only the owner users and tested using data collected from both owners and attackers.3⃝Rapid Authentication to quickly identify drivers’identities using a few pressure samples collected within short durations(1,2,3,5,or 10 s).4⃝Realistic experiments where the sensory data is collected from real experiments rather than computer simulation tools.We conducted real experiments and collected about 13,200 samples and 22,800 samples of belt-only and seat-only datasets from all 12 users under different settings.To evaluate system effectiveness,we implemented extensive evaluation scenarios using four one-class detectors One-Class Support Vector Machine(OCSVM),Local Outlier Factor(LOF),Isolation Forest(IF),and Elliptic Envelope(EE),three dataset types(belt-only,seat-only,and fusion),and four different dataset sizes.Our average experimental results show that the system can authenticate the driver with an F1 score of 93.1%for seat-based data using OCSVM classifier,an F1 score of 98.53%for fusion-based data using LOF classifier,an F1 score of 91.65%for fusion-based data using IF classifier,and an F1 score of 95.79%for fusion-based data using EE classifier.展开更多
The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics.But they are not independently applicable to any environment and have their own scope of applic...The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics.But they are not independently applicable to any environment and have their own scope of application.In addition,about the master cylinder pressure control,there are few studies that can simultaneously balance pressure building accuracy,speed,and prevent pressure overshoot and jitter.In this paper,an adaptative fusion method based on electro-hydraulic characteristic and vehicle mode is proposed to estimate the master cylinder pressure.The fusion strategy is mainly based on the prediction performance of two algorithms under different vehicle speeds,pressures,and ABS states.Apart from this,this article also includes real-time prediction of the friction model based on RLS to improve the accuracy of the electro-hydraulic mode.In order to simultaneously balance pressure control accuracy,response speed,and prevent overshoot and jitter,this article proposes an adaptative LQR controller for MC pressure control which uses fuzzy-logic controller to adjust the weights of LQR controller based on target pressure and difference compared with actual pressure.Through mode-in-loop and hardware-in-loop tests in ramp,step and sinusoidal response,the whole estimation and control system is verified based on real hydraulic system and the performance is satisfactory under these scenes.This research proposes an adaptative pressure estimation and control architecture for integrated electro-hydraulic brake system which could eliminate pressure sensors in typical scenarios and ensure the comprehensive performance of pressure control.展开更多
Quasi-one-dimensional systems provide a unique platform for the exploration of novel quantum states due to their enhanced electronic correlations,strong anisotropy,and dimensional confinement.Among various external tu...Quasi-one-dimensional systems provide a unique platform for the exploration of novel quantum states due to their enhanced electronic correlations,strong anisotropy,and dimensional confinement.Among various external tuning methods,physical pressure has been experimentally demonstrated to be an exceptionally potent and precise method for modulating both the structural and electronic properties of quasi-one-dimensional systems.In this review,we focus on the application of pressure to construct pressure-temperature phase diagrams of quasi-one-dimensional materials and explore the intricate relationships among quantum phenomena between superconductivity and other electronic states,such as charge density wave,topological quantum states,and antiferromagnetism.By analyzing representative examples across distinct material families,we demonstrate how pressure can be used not only to induce superconductivity but also to reveal underlying quantum critical points and drive topological phase transitions.We emphasize the significant potential of pressure as a crucial tuning parameter for revealing novel quantum phenomena and driving the progress in advanced low-dimensional quantum materials.展开更多
Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accur...Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accurate overpressure prediction remains challenging in offshore Northwest Borneo despite several decades of drilling experience.This paper focuses on two exploration wells drilled by Brunei Shell Petroleum 40 years apart that faced similar challenges with overpressure prediction and well control.An integrated lookback study is attempted using seismic and well-log data to explore the causes of the unsatisfactory Pore Pressure Prediction(PPP)outcome in pre-drill and real-time operation settings for thesewells.Our study indicates that the misprediction of overpressures is due to real differences in shale pressure(basis of pre-drill work and monitoring)and sand pressure(source of drill kick and well control chal-lenges)due to large-scale vertical leak or expulsion of deep-seated fluids into pre-compacted normally pressured overlying sediments in several regions through a mix of shear and tensile failure mechanisms.Such migrated fluids inflate the sand pressure in the normally compacted shallower sequences with the shale pressure remaining low.A predictive framework for upward fluid expulsion was attempted but found impracticable due to complex spatial and temporal variations in the horizontal stress field responsible for such leakage.As such,it is proposed that these migratory overpressures are essentially'unpredictable'from conventional PPP workflows viewed in the broad bucket of compaction disequi-librium(undercompaction)and fluid expansion(unloading)mechanisms.Further study is recommended to understand if such migrated overpressures in the sand can produce a discernible and predictable geophysical or petrophysical signature in the abutting normally compacted shales.The study highlights the possibility of large lateral variability in the sand overpressure within the same stratigraphic unit in regions with complex tectonostratigraphic evolution like Northwest Borneo.展开更多
The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosi...The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosite(Pb-J)were 130℃,30 g/L H_(2)SO_(4),15 g/L Fe^(3+),and an oxygen partial pressure of 0.4 MPa.Furthermore,increased Fe^(3+)concentration and oxygen partial pressure did not enhance jarosite formation.Conversely,lowering the temperature and increasing the H_(2)SO_(4) concentration facilitated PbSO_(4) formation and inhibited its further conversion to Pb-J.Additionally,the effects of potassium sulfate,sodium sulfate,and high concentrations of zinc sulfate on the phase transformation of galena were examined through leaching tests,XRD,SEM-EDS,and FT-IR analyses.All three sulfates inhibited the conversion of galena to Pb-J.Among these,potassium sulfate prevented Pb-J formation and converted it more thoroughly into potassium jarosite.However,high concentrations of zinc sulfate facilitated the crystallization of both PbSO_(4) and Pb-J,which altered the morphology of the product.Zinc ions coprecipitated with Pb-J,thereby integrating into the product.展开更多
文摘The paper describes the new pressurization system for the upper stage of launch vehicles and spacecraft and the flight test results of the vehicle which conform to the design of the system.
文摘Advanced high strength steels are the group of material with high strength and good formability, because high strength lesser gauge thickness can be used without compromising the function of component. In terms of economic forming process, hydroforming is the manufacturing option which uses a fluid medium to form a component by using high internal pressure. This process gained steep interest in the automotive and aerospace industries because of its many advantages such as part consolidation, good quality of the formed part etc. The main advantage is that the uniform pressure can be transferred to whole projected part at the same time. Low pressure tube hydroforming considered an inexpensive option for forming these advanced high strength steel. This paper investigates the pressurization system used during the low pressure tube hydroforming cycle. It is observed that the usage of ramp pressure cycle during forming the part from low pressure tube hydroforming results in lesser die holding force. Also, the stress, strain and thickness distribution of the part during low pressure tube hydroforming are critically analysed.
文摘The reliable and intelligent propulsion pressurization system is one of the key technologies of new Chinese generation launch vehicles; a high reliability design is an important guarantee for the success of launching. This paper analyzes the domestic and overseas liquid launch vehicles in the area of propulsion pressurization systems, based on comprehensive analysis, demonstrating the reliable and intelligent propulsion pressurization system of the Long March 7(Simplified as LM-7) has been raised. By applying a full chain redundancy design, setting proper pressure control bandwidth and control mode reconstruction under extreme fault conditions, the reliability and adaptability of the propulsion pressurization system has enhanced significantly. In addition, the complete system has been verified by the first two flights of LM-7.
基金financially supported by the National Natural Science Foundation of China, Project No. 51074210
文摘A new compact pressurization control system of the low pressure casting machine for crucible pressure casting has been developed. It is especially designed for the production of high-quality aluminum or magnesium alloy parts with low input cost. This machine with such a system has the virtue of economical and compact, and combines the Fuzzy-PID technology and achieves accuracies of ±2.5 mbar. At present, this machine has been adopted by several users in China for the production of aluminum alloy castings with high property requirements. Furthermore, for magnesium alloy castings, this machine can be used with the gas protect unit.
基金supported by the Ministry of Education and Science of the Russian Federation(No.2019-0251).
文摘A new gas preparation system(GasPS-RCS)is proposed to solve two tasks:(A)to heat helium gas for tank pressurization;(B)to prepare gas for the Launch Vehicle(LV)Reactive Control System(RCS)at the LV orientation and stabilization sections of the LV on passive parts of the flight trajectory,to provide conditions for launching the Liquid Rocket Engine(LRE).The system includes a gas generator based on hydrogen peroxide,a separator for water separation,heat exchangers independent of the LRE,and gas-jet nozzles.The proposed new system allowed to reduce the length of pressurizing gas lines and reduce the increased helium gas consumption during the heat exchanger warm-up interval of the LRE during its launch.A special advantage of the proposed system is the possibility of ground testing of heat exchangers without an operating LRE.A mathematical model based on the first law of thermodynamics was used to perform a comparative analysis of GasPS-RCS with traditional pressurization and RCS systems.To validate the mathematical model,the experimental studies of helium pressurizing of a liquid nitrogen tank were conducted.The results show that the deviation of experimental and calculated values for pressure is 1.1%and for temperature up to 2%.According to the results of comparative analysis,the GasPS-RCS is 259 kg lighter for the first stage and 80 kg lighter for the second stage of the LV.
文摘The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.
基金supported by Basic and Applied Basic research foundation of Guangdong province(Nos.2021A1515010343 and 2022A1515011582)the Science and Technology Program of Guangdong Province(Nos.2021A0505030026 and 2022A0505050029).
文摘In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-based alloy(typically pure lead or lead-bismuth eutectic(LBE))is used as the coolant.To clarify the pressure build-up characteristics under water-jet injection,this study conducted several experiments by injecting pressurized water into a molten LBE pool at Sun Yat-sen University.To obtain a further understanding,several new experimental parameters were adopted,including the melt temperature,water subcooling,injection pressure,injection duration,and nozzle diameter.Through detailed analyses,it was found that the pressure and temperature during the water-melt interaction exhibited a consistent variation trend with our previous water-droplet injection mode LBE experiment.Similarly,the existence of a steam explosion was confirmed,which typically results in a much stronger pressure build-up.For the non-explosion cases,increasing the injection pressure,melt-pool temperature,nozzle diameter,and water subcooling promoted pressure build-up in the melt pool.However,a limited enhancement effect was observed when increasing the injection duration,which may be owing to the continually rising pressure in the interaction vessel or the isolation effect of the generated steam cavity.Regardless of whether a steam explosion occurred,the calculated mechanical and kinetic energy conversion efficiencies of the melt were relatively small(not exceeding 4.1%and 0.7%,respectively).Moreover,the range of the conversion efficiency was similar to that of previous water-droplet experiments,although the upper limit of the jet mode was slightly lower.
文摘BACKGROUND Acute respiratory distress syndrome(ARDS)is a critical condition characterized by acute hypoxemia,non-cardiogenic pulmonary edema,and decreased lung compliance.The Berlin definition,updated in 2012,classifies ARDS severity based on the partial pressure of arterial oxygen/fractional inspired oxygen fraction ratio.Despite various treatment strategies,ARDS remains a significant public health concern with high mortality rates.AIM To evaluate the implications of driving pressure(DP)in ARDS management and its potential as a protective lung strategy.METHODS We conducted a systematic review using databases including EbscoHost,MEDLINE,CINAHL,PubMed,and Google Scholar.The search was limited to articles published between January 2015 and September 2024.Twenty-three peer-reviewed articles were selected based on inclusion criteria focusing on adult ARDS patients undergoing mechanical ventilation and DP strategies.The literature review was conducted and reported according to PRISMA 2020 guidelines.RESULTS DP,the difference between plateau pressure and positive end-expiratory pressure,is crucial in ARDS management.Studies indicate that lower DP levels are significantly associated with improved survival rates in ARDS patients.DP is a better predictor of mortality than tidal volume or positive end-expiratory pressure alone.Adjusting DP by optimizing lung compliance and minimizing overdistension and collapse can reduce ventilator-induced lung injury.CONCLUSION DP is a valuable parameter in ARDS management,offering a more precise measure of lung stress and strain than traditional metrics.Implementing DP as a threshold for safety can enhance protective ventilation strategies,po-tentially reducing mortality in ARDS patients.Further research is needed to refine DP measurement techniques and validate its clinical application in diverse patient populations.
文摘Beijing Aerospace System Engineering Institute of China Academy of Launch Vehicle Technology (CALT) declared recently that theinstitute has set up a laboratory whichwould operate a newly
文摘In order to address the current inability of screen printing to monitor printing pressure online,an online printing pressure monitoring system applied to screen printing machines was designed in this study.In this study,the consistency of printed electrodes was measured by using a confocal microscope and the pressure distribution detected by online pressure monitoring system was compared to investigate the relationship.The results demonstrated the relationship between printing pressure and the consistency of printed electrodes.As printing pressure increases,the ink layer at the corresponding position becomes thicker and that higher printing pressure enhances the consistency of the printed electrodes.The experiment confirms the feasibility of the online pressure monitoring system,which aids in predicting and controlling the consistency of printed electrodes,thereby improving their performance.
文摘Objective: To identify the principal factors associated with the occurrence and development of medical device-related pressure injuries (MDRPI) in adults admitted to hospitals. MDRPI, a peculiar subtype of pressure injuries (PI), result from the pression exerted by devices (or their fixation systems) applied for diagnostic and therapeutic purposes. MDRPI represent a serious problem for patients and healthcare systems. Understanding potential risk factors is an important step in implementing effective interventions. Methods: In this study, we will perform a systematic review;if possible, also a meta-analysis will be performed. The review will follow the preferred reporting items for systematic reviews and meta-analyses (PRISMA) reporting guidelines for systematic reviews. A rigorous literature search will be conducted both in electronic databases (Medline/PubMed, Embase, CINAHL, Web of Science, Scopus, Cochrane Library) to identify studies published since 2000 and in gray literature for unpublished studies. Pairs of researchers will identify relevant evidence, extract data, and assess risk of bias independently in each eligible study. Factors associated with the occurrence of MDRPI are considered the primary outcome. Secondary outcomes are prevalence and incidence of MDRPI, length of hospital stay, infections, and death. The evidence will be synthesized using the GRADE methodology. Results: Results are not currently available as this is a protocol for a systematic review. Conclusions: This systematic review will identify evidence on risk factors for developing MDRPI. We are confident that the results of this review will help to improve clinical practice and guide future research.
基金supported by the project MApping and Forecasting Ecosystem Services in Urban Areas(MAFESUR)funded by the Lithuanian Research Council(Contract:Nr.P-MIP-23-426).
文摘Coastal tourism holds substantial development potential.However,coastal ecosystems are affected by tourism development,which limits the supply of ecosystem services(ES).This study aims to conduct a systematic literature review on the impacts of tourism on coastal and marine ES using the Preferred Reporting Items for Systematic Reviews and Meta-alpha Methods.We initially identified 640 studies by searching titles,abstracts,and keywords.After screening,only 50 studies met the criteria for inclusion in the review.The results showed a significant increase in publications between 2011 and 2023.Most studies were conducted in Europe,Asia,and North and Central America.The most used ES classifications were MEA and CICES.Most studies concentrated on the ES supply dimension(43 studies;86%).Cultural ES(47 studies;94%)were researched more than provisioning(28 studies;56%)and regulating&maintenance(29 studies;58%)sections.Regarding cultural ES,most studies were focused on“Physical and experiential interactions with the natural environment”(34 studies;68%)and on provisioning ES on“Wild animals(terrestrial and aquatic)for nutrition,materials or energy”(18 studies;36%).Quantitative and mixed methods were the most used in the reviewed studies.Most studies identified pressures from“Tourism,urbanisation,and population increase”(27 studies;54%)and focused on“Integrative/common management strategies”(20 studies;40%).Only a few of the studies’results have been validated by external data(10 studies;20%).This study provides an overview of the most assessed marine and coastal ES,where studies are needed with more comprehensive geographic coverage.
文摘This research aims to understand the causes of fraud through the approach of the Fraud Triangle Theory,which includes three main factors:pressure,opportunity,rationalization.By using the Systematic Literature Review method from various relevant international journals,it analyzed systematically to identify patterns,trends,and theoretical contributions to efforts in detecting and preventing fraud.The results of this study show that the three factors in the Fraud Triangle Theory significantly contribute to the occurrence of fraud.Opportunity as the most dominant factor is caused by weak internal control systems and lack of oversight.In addition,economic pressure,and a permissive organizational environment,as well as the rationalization processes by individuals,also increase the tendency for a person to commit fraud.These findings emphasize the need for a comprehensive approach in fraud prevention strategies,through ethical values,the establishment of an organizational culture with integrity,and the implementation of more effective internal control and oversight.
基金supported by the National Natural Science Foundation of China(Grant Nos.12122405,12274169,and 11574109)the Fundamental Research Funds for the Central Universities。
文摘The high-pressure phase diagram of the Nb-Ti binary system at 0 K is explored by systematic crystal structure prediction.The results highlight a novel niobium-rich bcc phase,Nb_(7)Ti,which is the only dynamically stable ordered Nb-Ti compound under ambient pressure.Extensive first-principles calculations have provided insights into the electronic structure,bonding and superconducting properties of Nb_(7)Ti.The superconducting transition temperature(T_(c))for Nb_(7)Ti at ambient pressure is estimated within the framework of BCS theory to be about 17.5 K,which is significantly higher—nearly double—that of the widely utilized NbTi alloy.Furthermore,the results unveil that the high T_(c) is mainly attributed to the unique ordered lattice along with the strong electron-phonon coupling driven by interatomic interactions at mid-frequency and phonon softening induced by low-frequency Fermi surface nesting.Valuable insights are provided for the subsequent synthesis of application-oriented superconductors at low pressure.
基金supported by Chongqing Science and Technology Bureau Technology Innovation and Application Development Project(No.cstc2019jscx-msxmX0170)Chongqing Science and Health Joint Medical Research Project(No.2021MSXM208).
文摘Objective:To systematically evaluate the effectiveness of mobile health(mHealth)interventions on self-management and blood pressure(BP)control in patients with hypertension and to provide recommendations for the clinic and future research.Methods:Databases including Embase,Cochrane Library,CINAHL,CNKI,SinoMed,Wanfang,and Weipu were searched to collect systematic reviews(SRs)and meta-analyses on mHealth interventions for hypertension management.Two researchers independently screened the articles and extracted data,and the Assessment of Multiple Systematic Reviews(AMSTAR 2)was used to evaluate the methodological quality of the included reviews.Results:A total of 11 SRs were included:1 review was rated as high quality,3 as low quality,and 7 as critically low quality.The mobile phone was the most common intervention type,followed by the internet.Seven reviews performed meta-analyses and showed that mHealth was associated with a significant reduction in systolic blood pressure(SBP),from 2.28 mmHg(95%CI-3.90 to-0.66;I^(2)=40%)to 14.77 mmHg(95%CI 11.76-17.77;I^(2)=89.7%),and diastolic blood pressure(DBP),from 1.50 mmHg(95%CI-2.20 to-0.08;I^(2)=62%)to 8.17 mmHg(95%CI 5.67-10.67;I^(2)=86%).Self-management behaviors included medication adherence(MA),diet,smoking,alcohol drinking,physical activity,and BP monitoring.There were inconsistent results on the effectiveness of mHealth interventions.Conclusions:mHealth interventions can improve BP control,MA,diet,and smoking in patients with hypertension,but the evidence for the efficacy of mHealth on physical activity and alcohol drinking improvement is limited.The methodological quality of existing SRs on the management of BP in patients with hypertension was relatively low,and more well-designed SRs or meta-analyses were needed to provide more evidence.mHealth interventions are useful for improving BP control of patients with hypertension.
基金supported by the Institute of Information&Communications Technology Planning&Evaluation(1ITP)(Project Nos.RS-2024-00438551,30%,2022-11220701,30%,2021-0-01816,30%)the National Research Foundation of Korea(NRF)grant funded by the Korean Government(Project No.RS2023-00208460,10%).
文摘To date,many previous studies have been proposed for driver authentication;however,these solutions have many shortcomings and are still far from practical for real-world applications.In this paper,we tackle the shortcomings of the existing solutions and reach toward proposing a lightweight and practical authentication system,dubbed DriveMe,for identifying drivers on cars.Our novelty aspects are 1⃝Lightweight scheme that depends only on a single sensor data(i.e.,pressure readings)attached to the driver’s seat and belt.2⃝Practical evaluation in which one-class authentication models are trained from only the owner users and tested using data collected from both owners and attackers.3⃝Rapid Authentication to quickly identify drivers’identities using a few pressure samples collected within short durations(1,2,3,5,or 10 s).4⃝Realistic experiments where the sensory data is collected from real experiments rather than computer simulation tools.We conducted real experiments and collected about 13,200 samples and 22,800 samples of belt-only and seat-only datasets from all 12 users under different settings.To evaluate system effectiveness,we implemented extensive evaluation scenarios using four one-class detectors One-Class Support Vector Machine(OCSVM),Local Outlier Factor(LOF),Isolation Forest(IF),and Elliptic Envelope(EE),three dataset types(belt-only,seat-only,and fusion),and four different dataset sizes.Our average experimental results show that the system can authenticate the driver with an F1 score of 93.1%for seat-based data using OCSVM classifier,an F1 score of 98.53%for fusion-based data using LOF classifier,an F1 score of 91.65%for fusion-based data using IF classifier,and an F1 score of 95.79%for fusion-based data using EE classifier.
基金Supported by National Natural Science Foundation of China(Grant Nos.52202494,52202495)Chongqing Special Project for Technological Innovation and Application Development(Grant No.CSTB2022TIAD-DEX0014).
文摘The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics.But they are not independently applicable to any environment and have their own scope of application.In addition,about the master cylinder pressure control,there are few studies that can simultaneously balance pressure building accuracy,speed,and prevent pressure overshoot and jitter.In this paper,an adaptative fusion method based on electro-hydraulic characteristic and vehicle mode is proposed to estimate the master cylinder pressure.The fusion strategy is mainly based on the prediction performance of two algorithms under different vehicle speeds,pressures,and ABS states.Apart from this,this article also includes real-time prediction of the friction model based on RLS to improve the accuracy of the electro-hydraulic mode.In order to simultaneously balance pressure control accuracy,response speed,and prevent overshoot and jitter,this article proposes an adaptative LQR controller for MC pressure control which uses fuzzy-logic controller to adjust the weights of LQR controller based on target pressure and difference compared with actual pressure.Through mode-in-loop and hardware-in-loop tests in ramp,step and sinusoidal response,the whole estimation and control system is verified based on real hydraulic system and the performance is satisfactory under these scenes.This research proposes an adaptative pressure estimation and control architecture for integrated electro-hydraulic brake system which could eliminate pressure sensors in typical scenarios and ensure the comprehensive performance of pressure control.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1932217,12374135,and 12304193)the National Key R&D Program of China(Grant Nos.2024YFA1408400 and 2018YFA0704300)+1 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB25000000)the Southeast University Interdisciplinary Research Program for Young Scholars,and the Open Research Fund of the Key Laboratory of Quantum Materials and Devices(Southeast University),Ministry of Education,China.
文摘Quasi-one-dimensional systems provide a unique platform for the exploration of novel quantum states due to their enhanced electronic correlations,strong anisotropy,and dimensional confinement.Among various external tuning methods,physical pressure has been experimentally demonstrated to be an exceptionally potent and precise method for modulating both the structural and electronic properties of quasi-one-dimensional systems.In this review,we focus on the application of pressure to construct pressure-temperature phase diagrams of quasi-one-dimensional materials and explore the intricate relationships among quantum phenomena between superconductivity and other electronic states,such as charge density wave,topological quantum states,and antiferromagnetism.By analyzing representative examples across distinct material families,we demonstrate how pressure can be used not only to induce superconductivity but also to reveal underlying quantum critical points and drive topological phase transitions.We emphasize the significant potential of pressure as a crucial tuning parameter for revealing novel quantum phenomena and driving the progress in advanced low-dimensional quantum materials.
文摘Overpressure prediction for exploratory drilling has become robust in most basins with increasing well control,high-quality seismic datasets,and proactive real-time overpressure monitoring while drilling.However,accurate overpressure prediction remains challenging in offshore Northwest Borneo despite several decades of drilling experience.This paper focuses on two exploration wells drilled by Brunei Shell Petroleum 40 years apart that faced similar challenges with overpressure prediction and well control.An integrated lookback study is attempted using seismic and well-log data to explore the causes of the unsatisfactory Pore Pressure Prediction(PPP)outcome in pre-drill and real-time operation settings for thesewells.Our study indicates that the misprediction of overpressures is due to real differences in shale pressure(basis of pre-drill work and monitoring)and sand pressure(source of drill kick and well control chal-lenges)due to large-scale vertical leak or expulsion of deep-seated fluids into pre-compacted normally pressured overlying sediments in several regions through a mix of shear and tensile failure mechanisms.Such migrated fluids inflate the sand pressure in the normally compacted shallower sequences with the shale pressure remaining low.A predictive framework for upward fluid expulsion was attempted but found impracticable due to complex spatial and temporal variations in the horizontal stress field responsible for such leakage.As such,it is proposed that these migratory overpressures are essentially'unpredictable'from conventional PPP workflows viewed in the broad bucket of compaction disequi-librium(undercompaction)and fluid expansion(unloading)mechanisms.Further study is recommended to understand if such migrated overpressures in the sand can produce a discernible and predictable geophysical or petrophysical signature in the abutting normally compacted shales.The study highlights the possibility of large lateral variability in the sand overpressure within the same stratigraphic unit in regions with complex tectonostratigraphic evolution like Northwest Borneo.
基金Projects(2023AG05008,202302AB080012)supported by the Yunnan Major Scientific and Technological Program,ChinaProject(202405AC350015)supported by the Science and Technology Talent Programme of Yunnan Province,China。
文摘The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosite(Pb-J)were 130℃,30 g/L H_(2)SO_(4),15 g/L Fe^(3+),and an oxygen partial pressure of 0.4 MPa.Furthermore,increased Fe^(3+)concentration and oxygen partial pressure did not enhance jarosite formation.Conversely,lowering the temperature and increasing the H_(2)SO_(4) concentration facilitated PbSO_(4) formation and inhibited its further conversion to Pb-J.Additionally,the effects of potassium sulfate,sodium sulfate,and high concentrations of zinc sulfate on the phase transformation of galena were examined through leaching tests,XRD,SEM-EDS,and FT-IR analyses.All three sulfates inhibited the conversion of galena to Pb-J.Among these,potassium sulfate prevented Pb-J formation and converted it more thoroughly into potassium jarosite.However,high concentrations of zinc sulfate facilitated the crystallization of both PbSO_(4) and Pb-J,which altered the morphology of the product.Zinc ions coprecipitated with Pb-J,thereby integrating into the product.
