Base Pressure Control with Semi-Circular Ribs at Critical Mach Number

When better fuel-air mixing in the combustion chamber or a reduction in base drag are required in vehicles,rockets,and aeroplanes,the base pressure control is activated.Controlling the base pressure and drag is necessary in both scenarios.In this work,semi-circular ribs with varying diameters(2,4,and 6 mm)positioned at six distinct positions(0.5D,1D,1.5D,2D,3D,and 4D)inside a square duct with a side of 15 mm are proposed as an efficient way to apply the passive control technique.In-depth research is done on optimising rib size for various rib sites.According to this study,the base pressure rises as rib height increases.Furthermore,the optimal location for the semi-circular ribs with a diameter of 2 mm is at 0.5D.The 1D location appears to be optimal for the 4 mm size as well.For the 6 mm size,however,the 4D position fills this function.

Screening, Treatment and Control of High Blood Pressure on Five Sites in Mali

Introduction: High blood pressure is defined as blood pressure greater than or equal to 140 mm Hg for systolic and or 90 mm Hg for diastolic. It constitutes a major public health problem, the leading chronic disease in the world. The objective was to determine the prevalence, treatment rate and control of hypertension. Methods: This was a cross-sectional and descriptive study which took place over a period of 6 months in a hospital environment and in the general population. Results: Of the 1000 participants, 637 had hypertension, giving a prevalence of 63.70% with a female predominance. Thirty-three percent (33%) were unaware of their high blood pressure. The age group 60 and more was the most represented (44%). A proportion of 33 and 23.20 were overweight and obese participants, respectively. Male subjects were more overweight than female, unlike obesity which was more common among female subjects. Sixty-two percent (62%) of hypertensives were treated, of whom 44% were non-compliant. The excessively high cost and consumption of medications as needed were the main factors in therapeutic non-compliance. Twenty-two percent (22%) of all hypertensive patients and 35% of treated hypertensive patients were controlled. Women were more treated but less observant and less controlled than men. Therapeutic coverage and combination therapy rates were lower in rural areas. Hypertensives who had a high level of education were better treated and controlled than those who had no level. Conclusion: High blood pressure remains a real public health problem in Mali. It is more common in people aged 60 and over and in females. One in three hypertensives were unaware of their hypertension. The majority received antihypertensive treatments, but only a minority of them had their hypertension controlled.

Blood Pressure Profile and Glycemic Control of Type 2 Diabetics and Hypertensives at the Yalgado Ouedraogo University Hospital: A Review of 116 Cases

Objective: The association hypertension and diabetes is important. The two pathologies may influence each other. The aim was to study the correlation between glycemic control and blood pressure control and to determine the factors associated with blood pressure control. Methodology: This was a descriptive cross-sectional study with an analytical focus over 7 months. Patients were recruited as outpatients and all underwent ambulatory blood pressure measure, glycated hemoglobin and creatinine measurements, and assessment of compliance with treatment. Results: During this period 116 patients were collected. The predominance was female 69%. The mean age of the patients was 62 ± 7 years with a peak between 60 and 70 years. The average age of hypertension was 12 years and that of diabetes 6 1/2 years. The most frequently associated cardiovascular risk factor was a sedentary lifestyle (71.5%) after age. 57.8% of patients were not controlled at the office, with a predominance of systolic hypertension (58.2%). 61.6% of patients were controlled by ambulatory blood pressure measure, a rate of 47.8% of white coat hypertension. Glycemic control was observed in 42.2% of cases and 87% of patients had good renal function (glomerular filter rate ≥ 60 ml/mn). Therapeutic compliance was good in 53.4% of cases and dual therapy was the most used therapeutic modality 44.8% (52 patients) followed by triple therapy. The factors associated with poor blood pressure control were glycemic imbalance, non-compliance and monotherapy. Dual therapy had a protective effect. Conclusion: The association of hypertension and type 2 diabetes is frequent. The risk of occurrence increases with age. Ambulatory blood pressure measure is the best method to assess blood pressure control. Optimization of blood pressure control should also include optimization of glycemic control.

Control system design for a pressure-tube-type supercritical water-cooled nuclear reactor via a higher order sliding mode method

Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWR)is a fourth-generation conceptual reactor.In an SCWR,the non-linear dynamics of the reactor require a controller capable of control-ling the nonlinearities.In this study,a pressure-tube-type SCWR was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled simultaneously.In an SCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power maneuvering.Reactor point kinetics equations with three groups of delayed neutrons were used in the simulation.Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous studies.The controlled parameters were reactor power,steam temperature,and pressure.Notably,for these parameters,the PI controller had certain instabilities in the presence of disturbances.The classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering phenomenon.HOSMC was highly accurate and stable and had a small computational cost.In reality,it followed the desired values without oscillations and chattering.

Synthetic analysis of meteorological elements for the sea fogs occurred in northwest the Yellow Sea under low pressure control and comparison with sea fogs occurred under high pressure control in summer

Based on the principle of transient perturbation analysis,in this paper,a method to objectively determine the weather pattern formed by sea fog is provided.On the basis of the classification results,the circulation situation,divergence and vertical velocity field,and the vertical profile of temperature and humidity are synthesized and analyzed.The basic characteristics of the circulation and physical field of sea fog under low pressure control(L type sea fog)are obtained,and the results are compared with the sea fog under the control of high pressure(H type sea fog):a)L type sea fogs potential height anomaly disturbance is mainly manifested in the low layer,and its average value is-65.66 gpm,gradually weakening upward;b)L type sea fogs inversion structure is weaker than H type sea fogs when it occurs,the fog layer is thicker and the high relative humidity level is high over the fog layer,while the H type sea fogs fog layer has a relatively obvious dry layer;c)L sea fog has three layers of structure at the vertical direction.The first layer 1000-950 hPa is convergence accompanied by weak rise and subsidence,the second layer 950-850 hPa is divergence accompanied by weak subsidence,and the third layer 850 to 500hPa is gradually strengthened.While there are two layer structures of the H type sea fog.1000 hPa is divergence accompanied by weak rising and sinking movement,950-500 hPa is a uniform subsidence movement.d)Probability density statistical analysis further quantified the vertical movement of L and H type sea fog and the distribution of relative humidity in each layer.These conclusions provide an important reference for forecasting the sea fog in the northwest of the Yellow Sea under the condition of low pressure circulation in summer.

Pressure-tracking control of a novel electro-hydraulic braking system considering friction compensation

This work presents an integrated pressure-tracking controller for a novel electro-hydraulic brake(EHB) system considering friction and hydraulic disturbances. To this end, a mathematical model of an EHB system, consisting of actuator and hydraulic sub-systems, is derived for describing the fundamental dynamics of the system and designing the controller. Due to sensor inaccuracy and measurement noise, a Kalman filter is constructed to estimate push rod stroke for generating desired master cylinder pressure. To improve pressure-tracking accuracy, a linear friction model is generated by linearizing the nonlinear Tustin friction model, and the unmodeled friction disturbances are assumed unknown but bounded. A sliding mode controller is designed for compensating friction disturbances, and the stability of the controller is investigated using the Lyapunov method. The performance of the proposed integrated controller is evaluated with a hardware-in-the-loop(HIL) test platform equipped with the EHB prototype. The test results demonstrate that the EHB system with the proposed integrated controller not only achieves good pressure-tracking performance, but also maintains robustness to friction disturbances.

Sliding Mode Control of Hydraulic Pressure in Electro-Hydraulic Brake System Based on the Linearization of Higher-Order Model

The possibility to enhance the stability and robustness of electrohydraulic brake(EHB)systems is considered a subject of great importance in the automotive field.In such a context,the present study focuses on an actuator with a four-way sliding valve and a hydraulic cylinder.A 4-order nonlinear mathematical model is introduced accordingly.Through the linearization of the feedback law of the high order EHB model,a sliding mode control method is proposed for the hydraulic pressure.The hydraulic pressure tracking controls are simulated and analyzed by MATLAB/Simulink soft considering separately different conditions,i.e.,a sine wave,a square wave and a square wave with superimposed sine disturbance.The results show that the proposed strategy can track the target within 0.25 s,and the mean observed error is less than 1.2 bar.Moreover,with such a strategy,faster response and less overshoot are possible,which should be regarded as significant advantages.

Clinical application of flexible ureteroscopic sheath with controllable intraluminal pressure in treating ureteral stones

Objective:The purpose of the study was to assess the clinical efficacy and safety of a combined perfusion suction platform with pressure feedback control function and an ureteroscopic suction sheath that can measure the ureteropelvic pressure in implementing lithotripsies.Methods:Fifty-two patients who underwent lithotripsy under intelligent monitoring of ureteral intraluminal pressure from June 2016 to January 2018 were retrospectively recruited.The inclusion standard was stone diameter>1.5 cm but<2.5 cm.After the 12/14 Fr suction sheath was placed,manometer interface and suction interface of the sheath were connected to the platform via the pressure sensor and suction tube,respectively.The ureteroscope was connected to the platform perfusion pump,and the crushed stones were aspirated out under negative pressure.Results:According to the location of the stone,21(40.4%)cases were classified as upper ureteral stones,19(36.5%)were midureteral stones,and 12(23.1%)were lower ureteral stones.Forty-seven patients underwent successful primary sheath placement and lithotripsy with a mean operative time of 34.5(standard deviation 18.3)min.Retrograde stone migration did not occur.There were eight patients with hematuria postoperatively.Serious complication was 1.9% with one case of ureteral perforation.Stone clearance was 95.7% at Day 1e2 postoperatively,and 100% at Day 30 postoperatively.Conclusion:Ureteroscopic lithotripsy with intelligent pressure control using our device improved the efficiency of the lithotripsy and rate of stone clearance.The safety of the operation can be ensured.It is worth popularization and application in clinical practice.

In-situ pressure-preserved coring for deep exploration:Insight into the rotation behavior of the valve cover of a pressure controller

In-situ pressure-preserved coring(IPP-Coring)is considered to be the most reliable and efficient method for the identification of the scale of oil and gas resources.During IPP-Coring,because the rotation behavior of the pressure controller valve cover in different medium environments is unclear,interference between the valve cover and inner pipe may occur and negatively affect the IPP-Coring success rate.To address this issue,we conducted a series of indoor experiments employing a high-speed camera to gain greater insights into the valve cover rotation behavior in different medium environments,e.g.,air,water,and simulated drilling fluids.The results indicated that the variation in the valve cover rotation angle in the air and fluid environments can be described by a one-phase exponential decay function with a constant time parameter and by biphasic dose response function,respectively.The rotation behavior in the fluid environments exhibited distinct elastic and gravitational acceleration zones.In the fluid environments,the density clearly impacted the valve cover closing time and rotation behavior,whereas the effect of viscosity was very slight.This can be attributed to the negligible influence of the fluid viscosity on the drag coefficient found in this study;meanwhile,the density can increase the buoyancy and the time period during which the valve cover experienced a high drag coefficient.Considering these results,control schemes for the valve cover rotation behavior during IPP-Coring were proposed for different layers and geological conditions in which the different drilling fluids should be used,e.g.,the use of a high-density valve cover in high-pore pressure layers.

Effect of Home Blood Pressure Telemonitoring Plus Additional Support on Blood Pressure Control:A Randomized Clinical Trial

Objective Current clinical evidence on the effects of home blood pressure telemonitoring(HBPT)on improving blood pressure control comes entirely from developed countries.Thus,we performed this randomized controlled trial to evaluate whether HBPT plus support(patient education and clinician remote hypertension management)improves blood pressure control more than usual care(UC)in the Chinese population.Methods This single-center,randomized controlled study was conducted in Beijing,China.Patients aged 30-75 years were eligible for enrolment if they had blood pressure[systolic(SBP)≥140 mmHg and/or diastolic(DBP)≥90 mmHg;or SBP≥130 mmHg and/or DBP≥80 mmHg with diabetes].We recruited 190 patients randomized to either the HBPT or the UC groups for 12 weeks.The primary endpoints were blood pressure reduction and the proportion of patients achieving the target blood pressure.Results Totally,172 patients completed the study,the HBPT plus support group(n=84),and the UC group(n=88).Patients in the plus support group showed a greater reduction in mean ambulatory blood pressure than those in the UC group.The plus support group had a significantly higher proportion of patients who achieved the target blood pressure and maintained a dipper blood pressure pattern at the12th week of follow-up.Additionally,the patients in the plus support group showed lower blood pressure variability and higher drug adherence than those in the UC group.Conclusion HBPT plus additional support results in greater blood pressure reduction,better blood pressure control,a higher proportion of dipper blood pressure patterns,lower blood pressure variability,and higher drug adherence than UC.The development of telemedicine may be the cornerstone of hypertension management in primary care.

Fuzzy Feedback Control for Electro-Hydraulic Actuators

Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.

Operational feasibility study of stagnation pressure reaction control for a mid-caliber non-spinning projectile

Controlled,guided munitions can reduce dispersion in the shot,while providing the capability of engaging both stationary and maneuvering targets.The Netherlands Organisation for Applied Scientific Research has developed a fin-less control technology called Stagnation Pressure Reaction Control(SPRC)that takes stagnation pressure air and directs it sideways to control non-spinning projectiles.In a previous study,this technology was demonstrated at Mach 2 wind-tunnel conditions to achieve up to 1.5°controllable angle of incidence for a non-spinning,aerodynamically unstable projectile-like test object.In an operational scenario,the decelerating projectile will experience a decline in control force while the simultaneous forward shift of the center of pressure increases the need for control force.Furthermore,angles of incidence exceeding 1.5°will be experienced under realistic flight conditions,especially against maneuvering targets.This work addresses these challenges and presents an operational feasibility study for a practical application of SPRC in a non-spinning mid-caliber gun-launched projectile,using experiment data on control latency and force of the earlier study.It illustrates the combined effect of the control-and stability dynamics and underlines the potential of an SPRC projectile as a precisionoperation ammunition.This research revealed that SPRC technology can stabilize and control the hypothesized projectile in a direct fire scenario against stationary and maneuvering targets.

Pressure control method and device innovative design for deep oil in-situ exploration and coring

Deep oil exploration coring technology cannot accurately maintain the in-situ pressure and temperature of samples, which leads to a distortion of deep oil and gas resource reserve evaluations based on conventional cores and cannot guide the development of deep oil and gas resources on Earth. The fundamental reason is the lack of temperature and pressure control in in-situ coring environments. In this paper, a pressure control method of a coring device is studied. The theory and method of deep intelligent temperature-pressure coupling control are innovatively proposed, and a multifield coupling dynamic sealing model is established. The optimal cardinality three term PID (Proportional-Integral-Differential) intelligent control algorithm of pressure system is developed. The temperature-pressure characteristic of the gas-liquid two-phase cavity is analyzed, and the pressure intelligent control is carried out based on three term PID control algorithms. An in-situ condition-preserved coring (ICP-Coring) device is developed, and an intelligent control system for the temperature and pressure of the coring device is designed and verified by experiments. The results show that the temperature-pressure coupling control system can effectively realize stable sealing under temperature-pressure fields of 140 MPa and 150 °C. The temperature-pressure coupling control method can accurately realize a constant pressure inside the coring device. The maximum working pressure is 140 MPa, and the effective pressure compensation range is 20 MPa. The numerical simulation experiment of pressure system control algorithm is carried out, and the optimal cardinality and three term coefficients are obtained. The pressure steady-state error is less than 0.01%. The method of temperature-pressure coupling control has guiding significance for coring device research, and is also the basis for temperature-pressure decoupling control in ICP-Coring.

Passive Control of Base Pressure in a Converging-Diverging Nozzle with Area Ratio 2.56 at Mach 1.8

In this study,a duct is considered and special attention is paid to a passive method for the control of the base pressure relying on the use of a cavity with a variable aspect ratio.The Mach number considered is 1.8,and the area ratio of the duct is 2.56.In particular,two cavities are examined,their sizes being 3:3 and 6:3.The used L/D spans the interval 1–10 while the NPRs(nozzle pressure ratio)range from 2 to 9.The results show that the control becomes effective once the nozzles are correctly expanded or under-expanded.The pressure contours at different NPR and L/D are presented.It is shown that the NPR and cavity location strongly influence the base pressure.The NPR,Mach number,and cavity aspect ratio have a strong effect on the base pressure in the wake region.

Hygienic and Dietary Measures in Cameroonian Hypertensive Patients Followed at the Douala General Hospital: Knowledge, Compliance and Effect on Blood Pressure Control

Introduction: The management of hypertension is mostly based on pharmacotherapy and hygienic and dietary measures (HDMs) for which little data is available in Cameroon. The concern to improve the quality of life of hypertensive patients led us to study the knowledge, compliance and effect of HDMs among Cameroonian hypertensive patients. Methods: This was a cross-sectional study carried out at the Douala General Hospital;the census of patients was carried out from 05 March to 10 May 2018. The data evaluated were knowledge and compliance with HDMs with an inference of their effect on blood pressure control. Results: We recruited 330 participants at mean age of 60 ± 11 years, 37.9% men;57.3% with blood pressure (BP) controlled. Out of 330 subjects, 308 (93.3%) who had been educated about dietary health measures for hypertension were assessed on knowledge, compliance and effect of these measures against 22 (6.7%) who had never heard about them. Around 85.7% of participants had good knowledge of HDMs and 78.9% had good compliance with them. There was no statistically significant influence of knowledge and compliance with HDMs on blood pressure control. Conclusion: The level of knowledge and adherence to HDMs of hypertensive patients at the Douala General Hospital was appreciable. It is however appropriate for physicians to intensify patient education on HDMs and BP control.

Control of Blood Pressure and Complication Presence in Khartoum State, Sudan

Background: Hypertension is a common chronic disease and an important public health problem. The prevention of complications depends on hypertension control. Aim: To assess blood pressure control, complication presence, and their influencing factors. Methods: This cross-sectional study was conducted on patients with hypertension attending a private medical facility, a governmental facility, and a primary health care center in Khartoum, Sudan, between September 2022 and February 2023. Statistical Package for Special Sciences version 25 was used for data analysis;frequency and percentage were used to describe the qualitative variables. A chi-square test was used for co-relation analysis;a P-value ≤ 0.05 was considered statistically significant, and the confidence interval was 95%. Results: The study included 250 participants;55.6% were males. Their age was 58.77 ± 6.80 years, and they had hypertension for 10.7 ± 8.51 years. The duration of the disease was 10.7 ± 8.51 years. Systolic blood pressure was 127.1 ± 11.3 mm hg, and diastolic blood pressure was 81.6 ± 7.1 mm hg. Of the participants, 76.4% had controlled hypertension, while 27.6% had complications due to hypertension. Controlled blood pressure was associated with females, age group 40 - 60 years, normal waist circumference, and high adherence level (P ≤ 0.05). The presence of complications was associated with males, participants older than 60 years, and a low adherence level (P ≤ 0.05). Conclusions: In Sudan, the level of control is good;nonetheless, not all patients achieve it. Availability and access to treatment facilities and medications should be improved. Proper patient counseling should be offered, as well as continuous care.

Clinical Analysis of Diabetic Nephropathy Risk Factors and Correlation with Blood Pressure Control

Objective:To explore the risk factors of diabetic nephropathy and its correlation with blood pressure control.Methods:A retrospective analysis of 80 patients with diabetic nephropathy(diabetic nephropathy group)and another 80 patients with diabetes(diabetic group)who were admitted to the Department of Nephrology and Endocrinology at our hospital from October 2021 to October 2022 was conducted.The general data of the two groups were compared,the influencing factors associated with the two groups were analyzed unilaterally,and unconditional dichotomous logistic regression was performed to analyze the influencing factors in patients with diabetic nephropathy.Results:There were no significant differences in high-density lipoprotein,systolic blood pressure,diastolic blood pressure,and creatinine between the two groups(P>0.05);however,compared with the diabetic group,the DN group had significantly elevated glycated hemoglobin,low-density lipoprotein,24-h urine protein,insulin resistance,and diabetes duration≥10 years(P<0.05).Conclusion:The clinical research on the correlation between the incidence of hypertension and the control of blood pressure in patients with diabetic nephropathy should be strengthened in order to formulate reasonable and feasible treatment plans.

Analysis on Static Pressure Bearing Seal Characteristics of Guide Sleeve of Electro-hydraulic Servo Cylinder

As a typical bionic walking robot, hydraulic quadruped robot has attracted much attention because of its high mobility, strong load capacity and steady motion. The electro-hydraulic servo cylinder, as its power actuator, requires low friction, good lateral load resistance and high speed motion. The electro-hydraulic servo cylinder hydrostatic bearing seal guide sleeve is taken as the research object in this paper. By using Fluent software to analyze and contrast the film characteristics of rectangular and I-shaped oil chamber of hydrostatic bearing seal guide sleeve, the relationship between piston rod moving speed, eccentricity, oil film carrying capacity, friction force and leakage volume, as well as the relationship between oil feed flow and oil film bearing capacity, friction force, inlet pressure and leakage volume were analyzed. This study provides a theoretical basis for optimizing the static pressure bearing seal parameters.

Analysis of Multiple Annular Pressure in Gas Storage Well and High-Pressure Gas Well

In gas storage or high-pressure gas wells,annular pressure is an unavoidable threat to safe,long-term resource production.The more complex situation,however,is multiple annular pressure,which means annular pressure happens in not only one annulus but two or more.Such a situation brings serious challenges to the identification of well integrity.However,few researches analyze the phenomenon of multiple annular pressure.Therefore,this paper studies the mechanism of multi-annular pressure to provide a foundation for its prevention and diagnosis.Firstly,the multi-annular pressure is classified according to the mechanism and field data.Then the failure mechanism and function of the wellbore safety barriers in the process of passage formation are analyzed.Finally,some suggestions are put forward for identifying and controlling multi-annular pressure.The results show that gas storage wells and high-pressure gas wells have the conditions to generate pressure channels,which leads to the expansion of annular pressure from a single annulus to multiple annuli.The pressure channel is composed of the tubing string,casing string,and a cement mantle,and the failures among the three have causal and hierarchical relationships.According to the channel direction,it can be divided into two types:tubing-casing annulus to casing annulus and casing annulus to the tubing-casing annulus,of which the former is more harmful.Some measures can be considered to prevent pressure channeling,including improvement of cementing quality,revision of maximum allowable annular pressure,and suitable frequency of pressure relief.

PID Controller Optimization by GA and Its Performances on the Electro-hydraulic Servo Control System

A proportional integral derivative （PID） controller is designed and attached to electro-hydraulic servo actuator system （EHSAS） to control the angular position of the rotary actuator which control the movable surface of space vehicles. The PID gain parameters are optimized by the genetic algorithm （GA）. The controller is verified on the new state-space model of servo-valves attached to the physical rotary actuator by SIMULINK program. The controller and the state-space model are verified experimentally. Simulation and experimental results verify the effectiveness of the PID controller adaptive by GA to control the angular position of the rotary actuator as compared with the classical PID controller and the compensator controller.