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 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
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
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
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
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
Detecting sitting posture abnormalities in wheelchair users enables early identification of changes in their functional status.To date,this detection has relied on in-person observation by medical specialists.However,...Detecting sitting posture abnormalities in wheelchair users enables early identification of changes in their functional status.To date,this detection has relied on in-person observation by medical specialists.However,given the challenges faced by health specialists to carry out continuous monitoring,the development of an intelligent anomaly detection system is proposed.Unlike other authors,where they use supervised techniques,this work proposes using unsupervised techniques due to the advantages they offer.These advantages include the lack of prior labeling of data,and the detection of anomalies previously not contemplated,among others.In the present work,an individualized methodology consisting of two phases is developed:characterizing the normal sitting pattern and determining abnormal samples.An analysis has been carried out between different unsupervised techniques to study which ones are more suitable for postural diagnosis.It can be concluded,among other aspects,that the utilization of dimensionality reduction techniques leads to improved results.Moreover,the normality characterization phase is deemed necessary for enhancing the system’s learning capabilities.Additionally,employing an individualized approach to the model aids in capturing the particularities of the various pathologies present among subjects.展开更多
Despite significant Brazilian social programs to expand energy access,approximately one million people in rural Amazonia still lack electricity.Moreover,the existing rural electricity grid in the region is inadequate ...Despite significant Brazilian social programs to expand energy access,approximately one million people in rural Amazonia still lack electricity.Moreover,the existing rural electricity grid in the region is inadequate for supporting efficient small-scale production systems due to both the poor quality and high cost of supplied energy.In parallel,traditional wooden bridges in the Amazon have been progressively replaced by more durable concrete structures in recent years.In this context,this study explores the application of very low-head hydropower installations in the Amazon,focusing on integrating axial-flow turbines beneath small concrete bridges.The methodology involves analyzing flow duration curves and key hydraulic parameters upstream and downstream to design a micro-hydropower system comprising two or more units,thereby maximizing annual energy generation.Additionally,the study assesses the applicability of the minimum pressure coefficient criterion to improve the efficiency of very low-head turbines.This design criterion is first validated against an existing experimental study featuring a propeller turbine with a simple curved plate blade.The proposed methodology is then applied to a case study involving a small dam-bridge with a head variation from 1.4 to 2.4 m and a flow rate ranging from 0.23 to 0.92 m^(3)/s.The optimal configuration achieves an energy output of 26.2 MWh/year with an efficiency of up to 86%.展开更多
Multimodal information sensing becomes increasingly critical under the rapid development of automation and information technology.With the ability to provide high-density and high-sensitivity pressure detection,pressu...Multimodal information sensing becomes increasingly critical under the rapid development of automation and information technology.With the ability to provide high-density and high-sensitivity pressure detection,pressure sensor arrays have been applied to a variety of fields,including intelligent robotics,medical monitoring,and industrial automation.This study proposes a pressure sensor array system based on the Minecraft game platform.The simulation and testing of the pressure sensor arrays system have been conducted using redstone circuits and pressure plates in Minecraft to simulate real-world piezoelectric pressure sensor arrays.A series of experiments verified the feasibility and effectiveness of the system.展开更多
In this work,an oscillating-body wave energy converter(OBWEC)with a hydraulic power take-off(PTO)system named“Dolphin 1”is designed,in which the hydraulic PTO system is equivalent to a transfer station and plays a c...In this work,an oscillating-body wave energy converter(OBWEC)with a hydraulic power take-off(PTO)system named“Dolphin 1”is designed,in which the hydraulic PTO system is equivalent to a transfer station and plays a crucial role in ensuring the stability of the electrical energy output and the efficiency of the overall system.A corresponding mathematical model for the hydraulic PTO system has been established,the factors that influence its performance have been studied,and an algorithm for solving the optimal working pressure has been derived in this paper.Moreover,a PID control method to enable the hydraulic PTO system to automatically achieve optimal performance under different wave conditions has been designed.The results indicate that,compared with single-chamber hydraulic cylinders,double-chamber hydraulic cylinders have a wider application range and greater performance;the accumulator can stabilize the output power of the hydraulic PTO system and slightly increase it;excessively large or small hydraulic motor displacement hinders system performance;and each wave condition corresponds to a unique optimal working pressure for the hydraulic PTO system.In addition,the relationship between the optimal working pressure P_(m)and the pressure P_(h)of the wave force acting on the piston satisfies P_(m)^(2)=∫_(t_(1))^(t_(2))P_(h)^(2)dt/(t_(2)-t_(1)).Furthermore,adjusting the hydraulic motor displacement automatically via a PID controller ensures that the actual working pressure of the hydraulic PTO system consistently reaches or approaches its theoretically optimal value under various wave conditions,which is a very effective control method for enhancing the performance of the hydraulic PTO system.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.
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.
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.
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FEDER/Ministry of Science and Innovation-State Research Agency/Project PID2020-112667RB-I00 funded by MCIN/AEI/10.13039/501100011033the Basque Government,IT1726-22+2 种基金by the predoctoral contracts PRE_2022_2_0022 and EP_2023_1_0015 of the Basque Governmentpartially supported by the Italian MIUR,PRIN 2020 Project“COMMON-WEARS”,N.2020HCWWLP,CUP:H23C22000230005co-funding from Next Generation EU,in the context of the National Recovery and Resilience Plan,through the Italian MUR,PRIN 2022 Project”COCOWEARS”(A framework for COntinuum COmputing WEARable Systems),N.2022T2XNJE,CUP:H53D23003640006.
文摘Detecting sitting posture abnormalities in wheelchair users enables early identification of changes in their functional status.To date,this detection has relied on in-person observation by medical specialists.However,given the challenges faced by health specialists to carry out continuous monitoring,the development of an intelligent anomaly detection system is proposed.Unlike other authors,where they use supervised techniques,this work proposes using unsupervised techniques due to the advantages they offer.These advantages include the lack of prior labeling of data,and the detection of anomalies previously not contemplated,among others.In the present work,an individualized methodology consisting of two phases is developed:characterizing the normal sitting pattern and determining abnormal samples.An analysis has been carried out between different unsupervised techniques to study which ones are more suitable for postural diagnosis.It can be concluded,among other aspects,that the utilization of dimensionality reduction techniques leads to improved results.Moreover,the normality characterization phase is deemed necessary for enhancing the system’s learning capabilities.Additionally,employing an individualized approach to the model aids in capturing the particularities of the various pathologies present among subjects.
基金funded by the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq),project number 408034/2022−0.
文摘Despite significant Brazilian social programs to expand energy access,approximately one million people in rural Amazonia still lack electricity.Moreover,the existing rural electricity grid in the region is inadequate for supporting efficient small-scale production systems due to both the poor quality and high cost of supplied energy.In parallel,traditional wooden bridges in the Amazon have been progressively replaced by more durable concrete structures in recent years.In this context,this study explores the application of very low-head hydropower installations in the Amazon,focusing on integrating axial-flow turbines beneath small concrete bridges.The methodology involves analyzing flow duration curves and key hydraulic parameters upstream and downstream to design a micro-hydropower system comprising two or more units,thereby maximizing annual energy generation.Additionally,the study assesses the applicability of the minimum pressure coefficient criterion to improve the efficiency of very low-head turbines.This design criterion is first validated against an existing experimental study featuring a propeller turbine with a simple curved plate blade.The proposed methodology is then applied to a case study involving a small dam-bridge with a head variation from 1.4 to 2.4 m and a flow rate ranging from 0.23 to 0.92 m^(3)/s.The optimal configuration achieves an energy output of 26.2 MWh/year with an efficiency of up to 86%.
文摘Multimodal information sensing becomes increasingly critical under the rapid development of automation and information technology.With the ability to provide high-density and high-sensitivity pressure detection,pressure sensor arrays have been applied to a variety of fields,including intelligent robotics,medical monitoring,and industrial automation.This study proposes a pressure sensor array system based on the Minecraft game platform.The simulation and testing of the pressure sensor arrays system have been conducted using redstone circuits and pressure plates in Minecraft to simulate real-world piezoelectric pressure sensor arrays.A series of experiments verified the feasibility and effectiveness of the system.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52071094 and 51979065).
文摘In this work,an oscillating-body wave energy converter(OBWEC)with a hydraulic power take-off(PTO)system named“Dolphin 1”is designed,in which the hydraulic PTO system is equivalent to a transfer station and plays a crucial role in ensuring the stability of the electrical energy output and the efficiency of the overall system.A corresponding mathematical model for the hydraulic PTO system has been established,the factors that influence its performance have been studied,and an algorithm for solving the optimal working pressure has been derived in this paper.Moreover,a PID control method to enable the hydraulic PTO system to automatically achieve optimal performance under different wave conditions has been designed.The results indicate that,compared with single-chamber hydraulic cylinders,double-chamber hydraulic cylinders have a wider application range and greater performance;the accumulator can stabilize the output power of the hydraulic PTO system and slightly increase it;excessively large or small hydraulic motor displacement hinders system performance;and each wave condition corresponds to a unique optimal working pressure for the hydraulic PTO system.In addition,the relationship between the optimal working pressure P_(m)and the pressure P_(h)of the wave force acting on the piston satisfies P_(m)^(2)=∫_(t_(1))^(t_(2))P_(h)^(2)dt/(t_(2)-t_(1)).Furthermore,adjusting the hydraulic motor displacement automatically via a PID controller ensures that the actual working pressure of the hydraulic PTO system consistently reaches or approaches its theoretically optimal value under various wave conditions,which is a very effective control method for enhancing the performance of the hydraulic PTO system.
