This article demonstrates the results of experimental research one of the pulsators. Its main difference from others is a pneumatic electromagnetic pulsator in combination with a collector. ...Therefore, this article describes in detail the process of studying the pulsator. The planned experiment was carried out on by Factorial experiments with multiple factors. The influence of factors (the ripple frequency n, the milk ejection q and the ratio between strokes t/T) on the vacuum pressure in the inter wall chamber of teat cups was studied. The regression equation of the dependence response criterion on factors is modeled. This dependence is demonstrated graphically. Also there is a contour graph which is for more detailed information.
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•High frequency fatigue data were measured on smooth and notched samples made of 304L steel.•The critical length parameter was derived from experimental data based on critical ...distance theory.•The critical length parameter serves for lifetime predictions of notched samples and components.•The length parameter increases from 0 to 2.5 mm with increasing applied stress amplitude.
In this paper, the fatigue data of smooth and notched specimens are evaluated using the method based on the theory of critical distances. This method is suitable for predictions of the fatigue lifetime of notched specimens using the axial stress distributions, the length parameter, and experimental data measured on smooth specimens. The critical length parameter lcr is determined from the relationship between two fatigue curves (one generated by testing smooth specimens and the other generated by testing specimens with a model notch). Experimental fatigue data are obtained using an ultrasonic fatigue pulsator at a frequency of 20 kHz and a load stress ratio R = −1. The paper describes the dependence of the critical length parameter for different notch radii on the number of cycles to fracture, as well as on the applied stress amplitude. The obtained results prove the possibility of using the critical length parameter for fatigue life prediction of notched specimens.
In this paper, we report the detection of amplitude modulation in a δ Scuti star HD 118660. We found that the p-mode frequency at 24.3837 d−1 varies periodically in amplitude with frequency ...0.0558±0.00147 d−1. However, all other modes are stable in both amplitude and phase which is clear evidence of non-conservation of visible pulsation mode energy. We constructed a two-frequency model by superimposing two sinusoïds with frequencies ν1 = 24.3837 d−1 and ν2 = 24.4420 d−1 and corresponding phases ϕ1 = 0.5211 rad and ϕ2 = 0.9481 rad to mimic the observed variations of amplitude and phase with time. The plausible explanation of the amplitude modulation in HD 118660 is due to beating of two unresolved closed frequencies ν1 and ν2.
Objective:
to investigate the effectiveness of a new mechanized lymphatic drainage method in acute decompensated heart failure (ADHF) modeling through local reduction in venous pressure in the site ...of lymphatic drainage from the thoracic duct.
Materials and methods.
Main components of the device are a catheter with built-in inlet and outlet mechanical valves designed for insertion into the left brachiocephalic vein through the left internal jugular vein. It comes with an extracorporeal drive system made as a valveless pulsator pump with a 10 ml shock discharge and a controller ensuring preset frequency and pressure/rarefaction duty cycle. The operating principle of the device is based on local reduction of venous pressure in the site of lymphatic drainage from the thoracic duct (in the junction of the left internal jugular and subclavian veins).
Results.
When modeling hydrodynamics under ADHF conditions on a hydrodynamic test bench, the upper venous flow through the left brachiocephalic vein was 0.4 l/min, the pressure in the site of lymphatic drainage from the thoracic duct, was decreased from 20–25 mmHg to 0–5 mmHg due to operation of the mechanized drainage device with suction/injection phase duration ratio 0.2/0.8 and pulsator pump operating frequency from 30 to 60 beats/min.
This paper describes the findings of static milking machine tests and milking observations on Uruguayan dairy farms. The aim of this study was to investigate the association between both milking ...machine performance and udder health management factors and bulk milk somatic cell count (BMSCC) in Uruguayan dairy herds. Data from 907 visits were used for the analysis. The farm visits were made between April 2006 and November 2015 and farms were located in 17 of the 19 departments of Uruguay. Each visit involved a short static machine test and observation of the milking process; the use of blanket dry cow therapy was also recorded. The BMSCC was the variable of interest. Univariable analysis was applied to explore the best set of predictors to be included in the multivariable model. A multivariable linear regression model was fitted. The median BMSCC over the years was 376 thousand cells/mL (interquartile range = 280,000–500,000 cells/mL). The final model showed a lower BMSCC for herds that used post-milking teat disinfection, applied the teat cups to dry teats and maintained the pulsation system in good working order. There was no significant association between BMSCC and blanket dry cow therapy in the final model. The association of these milking machine and udder health management factors with the BMSCC under Uruguayan conditions is relevant information for a dairy industry that needs low BMSCCs to compete on the world market.
Abstract
Bei zyklisch beanspruchten Betontragwerken besteht die Herausforderung, die Nutzungsdauer zunehmend filigraner Baustrukturen und vorgespannter Systeme mit sehr hohen Lastwechselzahlen
N
> 10
...7
bemessungstechnisch abzusichern. Dies erfordert technische Spezifikationen, die unter Berücksichtigung eines hinreichend genauen Materialverständnisses das Ermüdungsverhalten unter sehr hohen Lastwechselzahlen realitätsnah abbilden. Die derzeitigen Bemessungsgrundlagen in Form von Wöhlerlinien beschränken sich für Betonbauteile bisher auf versuchstechnisch verifizierte Lastwechselzahlen bis
N
= 10
7
. Durch die Entwicklung einer gezielt zum Schwingen anregbaren Versuchsvorrichtung war es am IMB/MPA Karlsruhe des Karlsruher Instituts für Technologie (KIT) möglich, erste Versuche an einem hochfesten Beton C120 unter Nutzung eines Hochfrequenzpulsators zur Erzeugung von Druckschwellbeanspruchungen durchzuführen. Der Beitrag fasst die Untersuchungsergebnisse zusammen und weist auf weitergehende thematische Fragestellungen bezüglich des Ermüdungsverhaltens von Beton unter sehr hohen Lastwechselzahlen hin.
Abstract
Fatigue characteristics of high‐strength concrete with very high numbers of load cycles
For more and more filigreed as well as prestressed concrete structures very high numbers of load cycles
N
> 10
7
occur during service life. This shall be implemented in adequate design rules. Therefore, technical specifications reflecting cyclic actions with very high numbers of load cycles and a sufficient precise understanding of fatigue behavior of the building materials are necessary. Currently available design rules based on S‐N curves for concrete building components are verified by testing up to a number of load cycles N of not more than
N
= 10
7
. Using a special test rig at IMB/MPA Karlsruhe of Karlsruhe Institute of Technology (KIT), tests with specimens made of a high‐strength concrete grade C120 were carried out, including the development and verification of the suitability of this test method. The following article summarizes the test results and points out unknown thematic aspects due to fatigue of concrete structures with very high numbers of load cycles.
The nozzle which is applied in industrial pneumatic pulsators is studied. It is a part of the system for unclogging the drains and outlets of silos and hoppers for loose materials. The nozzle is ...required to achieve the lowest level of energy losses while directing the airflow, which impacts the loose material bed. The energy rate transferred into the bed depends on the temperature and pressure differences between the inlet and outlet of the nozzle. In this study, the available energy is determined assuming compressible and transient airflow through the nozzle, which is a part of the industrial pneumatic pulsator. Numerical simulations are performed using the OpenFOAM CFD toolbox. Energy analysis is carried out by using Reynolds Transport Theorem for specific energy for the variable temperature inside the silo on the basis of CFD results. In fact, the air parameters at the outlet of the nozzle are the ones inside the silo. The study showed that the design of the nozzle is not very sufficient from an energetic point of view.
The objective of this study was to investigate the change of fabric movement by introducing a pulsator in a front-loading washer. To examine the effect of the changed fabric movements on washing ...performance, detergency, mechanical action, wrinkling, tangling, and tensile strength were also investigated.
Three-dimensional fabric movement was analyzed by representing the fabric center in the washer as XYZ coordinate values. Seven indexes of fabric movement were used to analyze the correlation between fabric movement and detergency. On comparing fabric movements using the indexes, the front-loading washer with a built-in pulsator showed more diverse fabric movements than the conventional washer and, in particular, movement in the depth direction of the drum occurred more frequently in the newly developed system. This led to 7.6% higher detergency compared to the conventional one, possibly due to the increased interaction between fabrics. Regression analysis verified that the diversified fabric movements induced by the pulsator in the front-loading washer resulted in the improvement of detergency. The different fabric movements in the newly developed system also affected fabric damage, tangling and wrinkling.
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