Search results for "Holding time"

Ultrasonic Welding of PBT-GF30 (70% Polybutylene Terephthalate + 30% Fiber Glass) and Expanded Polytetrafluoroethylene (e-PTFE)

2021

The ultrasonic welding of polymeric materials is one of the methods often used in practice. However, each couple of material subjected to ultrasonic welding is characterized by different values of technological parameters. Therefore, the main objective of the research presented in this paper is to optimize the parameters for the ultrasonic welding of two materials, namely PBT-GF30 (70% polybutylene terephthalate + 30% fiber glass) and expanded polytetrafluoroethylene (e-PTFE). In this sense, the research was carried out considering a plate-type part made of PBT-GF30, which had a thickness of 2.1 mm, and a membrane-type part made of e-PTFE, with a thickness of 0.3 mm. The condition imposed o…

The effect of different starting procedures on sprinters' reaction time.

2012

We examined the effect of different false start rules and starters' holding time on athletics sprinters' reaction times. Reaction times from 210 female (25.2 ± 3.8 years) and 361 male (24.8 ± 3.8 years) 100 m sprinters, participating in international championships for seniors from 1997 to 2011, were analysed. Holding time calculations were based on television recordings from the analysed heats (n = 267). Mean reaction times have increased by 20% (0.03 s, P0.001) during a 15 year period due to stricter false start rules. Starters' holding times were between 1.3 and 2.2 s for the analysed competitions. There was a small but significant relationship between reaction time and starters' holding …

Trainability of underwater breath-holding time.

1984

From diving practice we know that breath-holding time (BHT) can be increased by training. This examination was set up to illuminate whether BHT underwater can be trained decisively in a short period of time. The authors investigated whether physiologic or psychological aspects are the main constituents of the above-mentioned BHT phenomenon. BHT and the "onset point" of involuntary respiratory movements of 64 subjects were registered after deep inspiration and immersion in ca. 1 m. Two different tests were set up: (I) 2 breath-holds per day on 5 consecutive days, (II) 5 repeated breath-holds with pauses of 3 min in between. BHT of the first test was shorter underwater than in similar experim…

On the packing–holding flow in the injection molding of thermoplastic polymers

1988

Injection molding tests were performed on a Ny66 resin. Data of mass entering the mold during the packing–holding stage as a function of filling flow rate and holding time are presented. The experimental results are discussed on the basis of a simple model of the packing–holding stage. Only a small part of density increase due to crystallization seams to be compensated by the packing–holding extra flow.

Effect of some injection molding processing conditions on weld lines characteristics

1988

The influence of injection and mold temperature as well as holding time on the knit-line characteristics in samples of Nylon 6 obtained by injection molding was analysed. The characteristics of the surface defect seem to be governed by the shrinkage rate and amount in the weld line zone.

Estimation of isometric strength: Intensity and holding time

1982

Byssochlamys nivea inactivation in pineapple juice and nectar using high pressure cycles

2009

The aim of this work was to assess the inactivation of Byssochlamys nivea ascospores in pineapple juice and nectar by combining pressure sequences involving high pressure cycles with relatively mild thermal processing. The effect of 550 and 600 MPa sustained pressures (holding time of 15 min), combinations of sustained pressures and pressure pulses (holding time of 10 s), and pressure cycles (two, three and five cycles of 550 and 600 MPa for 7.5, 5 and 3 min, respectively), at 20, 40, 60, 70, 80 and 90 °C were compared. B. nivea ascospores were inactivated by applying sustained a pressure of 600 MPa at 90 °C for 5 min (juice) and 15 min (nectar), and three and five cycles of pressure at 600…

Trainability of underwater breath-holding-time

1982

From diving practice we know that breath-holding time (BHT) can be increased by training. This examination was set up to illuminate whether BHT underwater can be trained decisively in a short period of time. The authors investigated whether physiologic or psychological aspects are the main constituents of the above-mentioned BHT phenomenon. BHT and the "onset point" of involuntary respiratory movements of 64 subjects were registered after deep inspiration and immersion in ca. 1 m. Two different tests were set up: (I) 2 breath-holds per day on 5 consecutive days, (II) 5 repeated breath-holds with pauses of 3 min in between. BHT of the first test was shorter underwater than in similar experim…