Increased milking vacuum in teatcups fitted with non-return valves

1988 ◽  
Vol 55 (4) ◽  
pp. 495-503 ◽  
Author(s):  
R. Jeffrey Andrews ◽  
Graeme A. Mein ◽  
David M. Williams
Keyword(s):  
Strain Energy ◽  
Air Leakage ◽  
Bench Tests ◽  
Vacuum Level ◽  
Milk Flow ◽  
The Mean ◽  
Pulsation Cycle ◽  
Return Valve ◽  
Maximum Pulsation ◽  
Collapse Phase

SummaryAn experimental non-return valve was fitted in the short milk tube so that flow was permitted only in one direction, away from the teat. Liner movement was minimal because no air admission to the liner above the valve was provided. The extent of liner opening therefore depended on the amount of milk extracted within a pulsation cycle and on any air leakage past the liner mouthpiece. Milking experiments using four cows showed that the mean vacuum level in nominally open liners of valved teatcups during peak milk flow was 8·6 kPa higher than in conventional teatcups. Bench tests showed that the increase in liner vacuum (LV) depended on the nominal plant vacuum level, the pressure difference between initial LV and maximum pulsation chamber vacuum, the liner elasticity and mounting tension. The main source of energy available to raise LV above the nominal plant vacuum is the release of strain energy, stored within the liner during the collapse phase of each pulsation cycle.

Teat thickness changes may provide biological test for effective pulsation

1996 ◽  
Vol 63 (2) ◽  
pp. 179-189 ◽  
Author(s):  
Jörn Hamann ◽  
Graeme A. Mein
Keyword(s):  
Dynamic Test ◽  
International Standards ◽  
Biological Test ◽  
Short Term ◽  
Flow Rates ◽  
Vacuum Level ◽  
Pulsation Rate ◽  
Milk Flow ◽  
Induced Changes ◽  
Pulsation Cycle

SummaryPulsation rates of 40, 60 and 80 cycles/min were combined with pulsator ratios of 50, 60, 70 or 80% in two experiments with different liners. Machine-induced, short-term changes in teat thickness of 14 cows were compared with milk flow rate characteristics and machine strip yields to evaluate the effectiveness of pulsation in relation to liner type. Post-milking teat thickness increased progressively as the b phase of the pulsation cycle was lengthened, and as the d phase was shortened, at all pulsator rates and with either liner. Teat thickness values increased significantly (P < 0·05) when the d phase was <15%. For ratios of 50 and 60%, teat thickness decreased progressively as pulsation rate was increased. At the higher ratios, thickness values were lowest at 60 cycles/min. Pulsation settings that tended to increase teat thickness values also increased both peak milk flow rates and machine strip yields. The influence of liner type on teat thickness changes appeared to be at least as important as the influence of pulsator ratios and greater than the effect of pulsation rate. If so, then international standards for acceptable pulsation characteristics cannot be defined solely in terms of pulsator settings. A limit of ±5% for machine-induced changes in thickness of the teat apex would be an additional guideline for effectiveness of pulsation in relation to both liner type and vacuum level. This could provide a basis for a dynamic test applied to milking cows under field conditions.

Effect of automatic cluster remover settings on milkability, milk quality and milking irregularities of crossbred cows

2019 ◽  
Vol 86 (2) ◽  
pp. 196-200
Author(s):  
Ahmad Fahim ◽  
Madan Lal Kamboj ◽  
Ajayvir Singh Sirohi ◽  
Mukesh Bhakat ◽  
Tushar Kumar Mohanty
Keyword(s):  
Dairy Cows ◽  
Somatic Cell Count ◽  
Peak Flow ◽  
Milk Quality ◽  
Flow Rates ◽  
Vacuum Level ◽  
Crossbred Cows ◽  
Milk Flow ◽  
Dairy Animals ◽  
The Mean

AbstractAutomatic cluster remover (ACR) settings regulate the end of milking by detaching the clusters based on milk flow dropping below a preset level, which needs to be standardised for different breeds of dairy animals based on their production. A study was conducted to find out the best ACR setting for milking Indian crossbred cows based on milkability, milking irregularities and milk quality. Fifty six crossbred dairy cows in lactations 1 to 4 were categorised into three groups based on the level of production; low (N = 16; <12 kg/d), medium (N = 32; 12–18 kg/d) and high (N = 08; >18 kg/d). The ACR settings tested were 0.1, 0.2, 0.3 and 0.4 kg/min, keeping the vacuum level and pulsation settings constant. The ACR settings significantly (P < 0.01) affected the milk yield at all levels of production with a significant effect (P < 0.01) on machine-on time at 0.4 kg/min. The yield during the first 2 min of milking, average flow and peak flow rates were not affected at any level of production. The average electrical conductivity in milk was significantly (P < 0.01) lower for the low and medium yield cows without affecting the mean somatic cell count. At 0.4 kg/min, more cluster reattachments were needed because of significant amount of milk remaining in the udders post-cluster removal.

Factors affecting vacuum within the teatcup liner during milking

1968 ◽  
Vol 35 (2) ◽  
pp. 303-316 ◽  
Author(s):  
C. C. Thiel ◽  
P. A. Clough ◽  
D. R. Westgarth ◽  
D. N. Akam
Keyword(s):  
Peak Flow ◽  
Vacuum Fluctuation ◽  
Flow Rates ◽  
Factors Affecting ◽  
Practical Consequence ◽  
Factors Associated ◽  
Milk Flow ◽  
The Mean ◽  
Pulsation Cycle

SummaryFactors associated with the milking cluster and the long milk tube which cause a diminished or a fluctuating vacuum within the liner of the teatcup assembly during simulated milking with an artificial udder fell into 3 groups. 1. Lower milk flow rates and admission of air at the clawpiece greatly decreased vacuum fluctuation within a pulsation cycle and increased the mean level of vacuum in the liner during that part of the cycle in which milk was flowing from the teat. 2. Larger bore of the short milk tube connecting the liner to the clawpiece, pulsation of the teatcup liners in pairs instead of all 4 together, and larger volume of the clawpiece bowl in the main decreased fluctuation in vacuum within the liner. 3. Larger bore and shorter length of the long milk tube connected to the clawpiece and decreased height above the outlet of the clawpiece to which the milk was raised mainly increased the mean vacuum in the liner during that part of the cycle in which milk was flowing from the teat.In a milking experiment with 75 cows mean overall fluctuations in milking vacuum within the liner in a pulsation cycle at peak flow were 11·5 and 4·8 inHg and corresponding mean levels of vacuum during that part of the cycle when milk was flowing from the teat were 11·75 and 13·0 inHg. There were no differences in milking performance of practical consequence.

Responses of the bovine teat to machine milking: measurement of changes in thickness of the teat apex

1988 ◽  
Vol 55 (3) ◽  
pp. 331-338 ◽  
Author(s):  
Jörn Hamann ◽  
Graeme A. Mein
Keyword(s):  
Positive Pressure ◽  
Vacuum Level ◽  
Machine Milking ◽  
Before And After ◽  
The Mean ◽  
High Degree

SummaryChanges in the teat apex before and after different milking treatments were measured with a spring-loaded caliper device known as a cutimeter which could detect changes in thickness of the tissues of the teat end, presumably due to congestion and/or oedema, with a high degree of accuracy (± 2%) and repeatability (r = 0·99). Teat end thickness increased with increasing vacuum level. The mean increase immediately after milking with a conventional cluster was 2% for 24 teats milked at 30 kPa, 8% at 50 kPa and 21% at 70 kPa. At these vacuum levels, the mean increases for the same teats milked with an unconventional (PKME) teatcup were 10, 18 and 25% respectively. Cyclic application of 35 kPa positive pressure to the pulsation chamber of a conventional teatcup operating at 50 kPa reduced teat end thickness by 8% compared with the mean premilking value. Although most teats returned to within ± 2% of their premilking thickness values by 1 h after milking, differences were apparent between different milking systems for up to 4 h postmilking.

On the Crack Initiated from the Bi-Material Notch Tip

2010 ◽  
Vol 452-453 ◽  
pp. 441-444 ◽  
Author(s):  
Tomáš Profant ◽  
Jan Klusák ◽  
Michal Kotoul
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Local Minimum ◽  
Plane Elasticity ◽  
Mean Value ◽  
Tangential Stresses ◽  
Density Factor ◽  
The Mean ◽  
Energy Density Factor

The bi-material notch composed of two orthotropic parts is considered. The radial and tangential stresses and strain energy density is expressed using the Stroh-Eshelby-Lekhnitskii formalism for the plane elasticity. The potential direction of the crack initiation is determined from the maximum mean value of the tangential stresses and local minimum of the mean value of the generalized strain energy density factor in both materials. Matched asymptotic procedure is used to derive the change of potential energy for the debonding crack and the crack initiated in the determined direction.

scholarly journals Overview of large building testing in Baltic countries

2020 ◽  
Vol 172 ◽  
pp. 05007
Author(s):  
Andrejs Nitijevskis ◽  
Vladislavs Keviss
Keyword(s):  
Quality Control ◽  
Pressure Difference ◽  
Leakage Rate ◽  
Air Leakage ◽  
Baltic Countries ◽  
Measurement Results ◽  
The Mean ◽  
Mandatory Testing ◽  
Air Leakage Rate ◽  
Large Building

The objectives of this paper are to review measurements of airtightness of 2 large building groups – middle size shops, and warehouses/distribution centres. The mean air leakage rate at 50 Pa pressure difference q50 was 1.04 m3/m2h and 1.35 m3/m2h for shops and warehouses respectively. Analysis of measurement results is valuable because it allows to make a conclusion about compliance of national and corporative construction airtightness norms with actual air barrier condition on a comissioning stage. In the concluding part of the study there are suggested ways to improve air barrier such as review of construction norms, implementation of a mandatory testing and quality control of a measurement.

scholarly journals Effect of milking vacuum level and overmilking on cows’ teat characteristics

2011 ◽  
Vol 59 (5) ◽  
pp. 193-202 ◽  
Author(s):  
M. Pařilová ◽  
L. Stádník ◽  
A. Ježková ◽  
L. Štolc
Keyword(s):  
Wall Thickness ◽  
Treatment Effects ◽  
Vacuum Level ◽  
Milk Flow ◽  
Before And After ◽  
Teat Canal ◽  
Test Treatment

The influence of milking vacuum and milk flow level (resp. detachment level) on cows’ teat characteristics were studied in four experiments. The MIXED procedure was used to test treatment effects on the level of teat length, teat thickness at the base and half-way between the teat end and the base of udder, teat canal length, teat end width, teat wall thickness, teat cistern width after milking and on differences between these teat characteristics measured before and after milking. A total of 51 cows were included in all experiments. All the cows had clinically healthy udders. Some cows were involved in two or more experiments. Finally, 330 teat measurements of 165 cows were taken and statistically processed. Vacuum and milking with or without overmilking significantly (P < 0.05-0.001) influence monitored parameters. Milking vacuum has an influence on two of three measured external teat parameters: teat diameter measured at the base of the teat and half-way between the udder base and the teat tip. Change in teat length measured before and immediately after milking was higher when higher vacuum of 45 kPa was used. Detachment level also has an influence on teat proportions. Overmilked teats were longer and narrower compared to non-overmilked teats. Interaction between milking vacuum and detachment level influences external teat parameters as well.

scholarly journals The Compound Influence of Texture and Microstructure on the Mechanical Properties of Low-C Steel Wires

1991 ◽  
Vol 13 (4) ◽  
pp. 243-260 ◽  
Author(s):  
P. Gangli ◽  
J. A. Szpunar ◽  
Sugondo
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Aspect Ratio ◽  
Yield Strength ◽  
Strain Energy ◽  
Size Parameter ◽  
Wire Axis ◽  
Steel Wires ◽  
The Mean ◽  
Homogeneous Strain

A series of experiments were made determining textural, microstructural, and mechanical properties in cold drawn, and spheroidization heat treated low-C steel wires (AISI-1018 and 1033 grades). It was found that texture exerted a significant influence on the mechanical properties, while microstructure had a comparable influence.Mechanical properties are represented by yield strength (YS), ultimate compressive strength (UCS) and by homogeneous strain energy (EHOM), defined by the integral of stress up to uniform elongation. Textural properties are represented by the Taylor-factor, M, the R-value, and by the maximum of the orientation distribution function (ODFMAX). Micro-structural properties are treated with the help of the aspect ratio parameter (1/√AR), where AR is the grain aspect ratio (length to ellipsoidal width), the grain size parameter (1/√D), and the mean free path between second phase spheroidized cementites √N.For cold drawn steel wires, homogeneous strain energy (EHOM) is well correlated to (1/√AR) and (ODFMAX). Yield strength, on the other hand, appears to be chiefly influenced by the aspect ratio parameter, thus here ODFMAX exerts less influence. The yield strength (YS) of annealed, spheroidization treated low-C wires are equally influenced by the grain size parameter (1/√D), the mean distance between spherulites (√N) and by ODFMAX.The textures of the cold drawn wires could be well described by the 〈110〉 fibre parallel to wire axis, and by the 〈111〉 fibre normal to wire axis. The annealed wires, while also featuring these two fibres, displayed a distinct {111}〈110〉single orientation.

An Incremental Criterion for Time-Dependent Failure of Materials

1976 ◽  
Vol 98 (2) ◽  
pp. 140-145 ◽  
Author(s):  
S. R. Bodner ◽  
U. S. Lindholm
Keyword(s):  
Failure Criterion ◽  
Strain Energy ◽  
Hydrostatic Stress ◽  
Time Dependent ◽  
Accumulation Of Damage ◽  
The Mean ◽  
Flow Law ◽  
Dependent Failure

A criterion for the time-dependent failure of materials is developed based upon the concept that failure results from an incremental accumulation of damage. The failure criterion is thereby explicitly tied to the incremental flow law describing the inelastic deformations. The damage increment is assumed as a product of functions of the stored strain energy due to inelastic deformations, the mean hydrostatic stress, and the damage itself. The consequences of the failure criterion for various types of loading are discussed.

Design of Energy Absorbing Structure Using Topology Optimization With a Multi-Material Model

2003 ◽  
Author(s):  
Daeyoon Jung ◽  
Hae Chang Gea
Keyword(s):  
Topology Optimization ◽  
Strain Energy ◽  
Effective Properties ◽  
Service Condition ◽  
Material Model ◽  
Three Phase ◽  
The Mean ◽  
Energy Absorbing ◽  
Dual Objectives ◽  
Mean Compliance

To accommodate the dual objectives of many engineering applications, one to minimize the mean compliance for the stiffest structure under normal service condition and the other to maximize the strain energy for energy absorption during excessive loadings, topology optimization with a multi-material model is applied to the design of energy absorbing structure in this paper. The effective properties of the three-phase material are derived using a spherical micro-inclusion model. The dual objectives are combined in a ratio formation. Numerical examples from the proposed method are presented and discussed.

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