pressure pulse
Recently Published Documents

The interaction between impeller and volute produces a complex and unsteady water flow. It involves the interference of the non-uniform flow (such as the impeller’s jet wake and a secondary flow). In this paper, the transient flow in a new type of dishwasher pump is investigated numerically. In addition, pressure measurements are used to validate the numerical method, and the simulation results agree well with the experiment. Three schemes, 0 rpm (revolutions per minute)/30 rpm/60 rpm, of volute speeds are investigated. Multiple monitoring points are set at different positions of the new dishwasher pump to record pressure-pulse signals. In addition, frequency signals are obtained using a Fast Fourier Transform, which is then used to analyze the effect of the volute tongue and the outflow of the impeller. The radial force on the principal axis is recorded, and the schemes with different rotation speeds of volute are compared. The results show that the volute speed has only a small effect on the pump performance. In addition, the speed of the volute mainly affects the flow field in the transition section located between impeller and volute. The difference of the flow field in the impeller depends on the relative position between the impeller and the volute. The time domain curve for the pressure pulse is periodic, and there is a deviation between the peak for the schemes in the outflow region. In the frequency domain, the characteristic frequency equals the blade passing frequency. In the outflow region, the effect of the volute speeds increases with increasing volute speed. For the radial force, the rotating volute strengthens the fluctuation of the radial force, which affects the operational stability of the pump. The shape of the vector distribution is most regular for the 30 rpm scheme, which indicates that the stability of the pump is the highest. This paper can be used to improve both the control and selection of volute speeds.

Background: Whether changes in blood pressure (BP) over women's midlife are more driven by chronological aging or the menopause transition (MT) has been debated. We sought to determine whether women can be classified into distinct trajectory groups based on pattern and level of systolic (SBP), diastolic blood pressure, pulse pressure (PP), and mean arterial pressure (MAP) over the MT, and to assess whether menopause-related factors predict the group and/or level of BP measures. Methods: Participants were from the Study of Women's Health Across the Nation (SWAN). Group-based trajectory modeling was used to identify women who shared distinct BP trajectories over time relative to menopause onset and to assess associations of menopause-related factors with trajectory group and/or level of BP measures. An accelerated rise relative to menopause onset suggests a menopause contribution. Results: The study included 3,302 multi-racial/ethnic women with BP measures over 17 follow-up visits (baseline age[SD]: 46.3[2.7]). Women were classified into either low, medium, or high trajectory group in each BP measure. The low SBP, PP, and MAP trajectories (in 35%, 53%, and 28% of the cohort, respectively) were rising slowly before menopause but showed a significant accelerated rise 1 year after menopause, indicating a menopause contribution. The remaining BP trajectories were rising up until menopause and either continued with the same rise or declined after menopause. A younger menopause age predicted the low SBP, PP, and MAP trajectories. A greater follicle-stimulating hormone level predicted lower SBP and PP levels, while vasomotor symptoms occurrence predicted higher SBP, PP, and MAP levels over time. Estradiol did not predict trajectory or level of any BP measure. Conclusions: Distinct BP trajectories over the MT exist that revealed a group of women whose SBP, PP, and MAP trajectories are consistent with a menopause contribution. Our findings support frequent monitoring of BP during the MT.

The forced movement of the submarine under the action of an acoustic pressure wave at rectilinear and uniform movement of the device is analyzed. The analysis of the dynamics of translational movement of the hull under the action of an acoustic pressure wave in an ideal environment, which makes it possible to assess the physical properties of the environment and the elastic properties of the outer hull on the value of the maximum movement of the submarine. It is proved that if the total pressure pulse is limited, then the water particles will receive certain displacements and it can be expected that under these conditions the displacement of the submarine will be determined. The results of the analysis make it possible to conduct a comparative analysis of the translational movement of the submarine under the action of an acoustic pressure wave, taking into account the characteristics of the moving medium, more precisely, taking into account the viscosity of the real medium

Abstract Unconventional and tight gas reservoirs are located in deep and competent formations, which requires massive fracturing activities to extract hydrocarbons. Some of the persisting challenges faced by operators are either canceled or non-productive fractures. Both challenges force oil companies to drill new substitutional wells, which will increase the development cost of such reservoirs. A novel fracturing method was developed based on thermochemical pressure pulse. Reactive material of exothermic components are used to generate in-situ pressure pulse, which is sufficient to create fractures. The reaction can vary from low pressure pulse, to a very high loading up to 20,000 psi, with short pressurization time. In this study, Finite Element Modeling (FEM) was used to investigate the impact of the generated pressure-pulse load, by chemical reaction, on the number of induced fractures and fracture length. Actual tests of pulsed fracturing conducted in lab scale using several block samples compared with modeling work. There was a great relationship between the pressure load and fracturing behavior. The greater the pulse load and pressurization rate, the greater the number of created fractures, and the longer the induced fractures. The developed novel fracturing method will increase stimulated reservoir volume of unconventional gas without introducing a lot of water to formation. Moreover, the new method can reduce formation breakdown pressure by around 70%, which will minimize number of canceled fracturing.

Introduction: Polycystic ovarian syndrome (PCOS) is an endocrine disorder which will affect the female’s reproductive health, there are many risk factors found in the PCOS individuals such as irregular menstrual cycle, infertility, obesity, excess hair growth, hyperandrogenemia. The aim of the study is to estimate the blood pressure and pulse rate among PCOS individuals and to compare it with the normal subjects. Materials and Methods: A group of 20 PCOS individuals and 20 normal individuals have been chosen from Saveetha dental college with age of 18-25 years whose blood pressure, pulse rate, waist circumference, BMI, BMR are measured, the blood pressure and pulse rate were measured with a automatic blood pressure monitoring machine and the waist circumference was measured with a inch tape from last rib and the iliac crest at its small parameter. The simple random sampling method is used to minimize the sampling bias. Data was collected and analyzed by an independent sample‘t’ test. Results: When comparing with control healthy individuals, the systolic blood pressure (SBP) of PCOS individuals seem to be higher than the control subjects. The diastolic blood pressure (DBP) is also slightly higher for PCOS individuals. The pulse rate of normal individuals is higher than the PCOS individuals. The diastolic blood pressure had a significant value of about 0.002 which is less than 0.05 so it is significant Conclusion: From this study it is evident that when PCOS is seen in women it not only affects the gynecological sphere it also affects the cardiovascular activity which may even have fatal outcomes. So it is mandatory for the PCOS subjects to have a proper diet, proper sleep, physical activity, and very importantly to have a stress free life.

Abstract Downhole wireless communication in the form of mud pulse telemetry enabled directional drilling over the past 60 years and has been hugely successful. Technologies like Measurement While Drilling (MWD), Logging While Drilling (LWD), and Geosteering would simply not exist without it. But in the Production and Producing end of the business, applications for downhole wireless communication have been less clear, especially where long distances and long-term monitoring are concerned. Several wireless technologies are in use today for long-term production applications. Electromagnetic (EM), acoustic, and pressure pulse telemetries are finding application as wireless production gauges, drill stem test tools, and drilling alternatives to pressure pulse. But the large-scale vision of, "Breaking the Wire!" in production wells has not yet occurred. Permanent Downhole Gauges (PDG) with an umbilical to surface are still the product of choice for long-term production monitoring. A history of wireless approaches in production applications will be given and the different methods used in the industry will be explained. A comparison and contrast of wireless telemetry methods will be explored, explained, and evaluated. Advantages and disadvantages will be listed for each approach. A ranking system will be employed to illustrate the evaluation results of the different wireless telemetry methods. New variants for wireless telemetry, power supplies, and measurement methods will be proposed. Preferred applications for each gauge type will be given. Downhole gauges can be improved by integrating pressure pulse, a downhole power generator, and downhole flow rate measurement into a single unit. The overall size can be ten times shorter than existing systems while still generating a larger wireless signal. Such a system would make wireless downhole gauges much more practical and should significantly increase their uptake in the industry. Real-time measurement of downhole pressure and downhole flow rate transforms the accuracy and effectiveness of Pressure Transient Analysis (PTA). Better reservoir understanding can be gained by using only drawdown tests, without shutting in the well. Smaller tools are generally more cost effective.

Abstract In late 2016, the Interstellar Boundary Explorer (IBEX) observed an enhancement of hydrogen energetic neutral atom (ENA) flux in ∼20° south from the nose direction. This enhancement was a consequence of an abrupt increase of the solar wind (SW) dynamic pressure observed at 1 au in late 2014. In subsequent years, the increased flux of 4.3 keV ENAs was observed at higher latitudes filling in the heliosheath, in ENAs at lower energies, and the Ribbon flux. We observe that the rapid increase of SW pressure occurs every solar cycle (SC) from the beginning of the regular in situ SW measurements in the ecliptic plane. The SW pressure pulse happens about 4.7 yr from the beginning of each SC, it is during the maximum phase of solar activity, and repeats with a period of ∼10.2 yr. These repeating pulses of the SW pressure can cause periodic SC variations of the ENA production in the heliosheath. We follow McComas et al. results for the relation between SW pressure increase and ENA flux enhancement to investigate the periodic SW pressure increases and their consequences for the heliosphere. Our study of time delay between the cause (pressure pulse at 1 au) and the consequence (ENA enhancement) show that IBEX observed in 2009–2011 remnants of the SW pressure pulse that happened during the maximum of SC 23.

Background: Brem industry workers can be at risk to get into heat strain in their workplace. The cases are caused by heat pressure, pulse rate, and body temperature. Purpose: To analyze the heat pressure, pulse rate, and body temperature that can influence the heat strain simultaneously to the workers of the Brem industry in the Kaliabu region, Madiun city, Indonesia. Method: The research is characteristic analytic observation quantitative with the cross-sectional approach in which a sample is 157 respondents with a total amount are 266 workers. The analysis test path use SPSS AMOS 23 accessories to analyze the data. Result: The results of the research are that heat stress does not influence the pulse rate (estimate 0, 02). Heat stress influences body temperature (estimate 0, 12). Heat stress does not influence the heat strain directly (estimate 0, 011). Pulse rate does not influence the heat strain (estimate 0, 08) and body temperature influences the heat strain (estimate 0, 04). Conclusion: Heat stress does not influence the heat strain directly but it influences the variety of body temperature so it needs to pay attention to the work duration time well. (7 hours working and 1 hour for taking rest). Also, it needed an arrangement of the room and adding the system of ventilation to get down the heat from the environment so heat strain can be restrained by checking the environment temperature and body temperature workers routine.