Dependence Of T0 Research Articles

A study of peeling-off tension in rotor spinning and its dependence on rotor and fibre variables part I: theoretical

While assessing the overall yarn tension in rotor spinning, most of the researchers have ignored the contribution of peeling-off tension (T0) assuming this being small. However, experiments in the present study showed a significant discrepancy between the calculated and the measured mean yarn tension due to neglect of T0. Further, T0 has a bearing in twist propagation and compacting the fibres in the zone of Peripheral Twist Extent (PTE) for ensuring continuity of the yarn formation. In the present study, a theoretical deduction has been made to estimate T0 by summing up the contributions due to fibre tension at the yarn formation point and the tension arising out of the length of the PTE sliding in the rotor groove. The dependence of T0 on various rotor and fibre variables has also been established.

Growth of PbSe Quantum Dots Within High‐Index Lead‐Phosphate Glass for Infrared Saturable Absorbers

PbSe quantum dots (QDs) were grown in high‐refractive‐index low‐melting‐temperature lead‐phosphate glass. The lowest energy exciton transition of the QDs was tuned over a wide range within the infrared spectral region (0.93–2.75 μm) by a controlled heat treatment. The measured QD radius ranged between 2 and 5.3 nm, with a time (t) dependence of t0.29 for long dwelling times during the heat treatment, indicating that the QD growth mechanism tends to follow Lifshitz‐Slyozov‐Wagner theory. The QD saturable absorber behavior at 1.2 μm had a measured saturation fluence of ~2.1 μJ/cm2.

Study of the austempering transformation kinetics in compacted graphite cast irons

In this work, the phases involved in the transformation austenite→ferrite+high-carbon austenite in cast irons were assessed by means of Mossbauer spectroscopy and hardness measurements for samples austempered at five different temperatures between 573 and 673 K with two Mn contents. The C content in the high-carbon austenite was found to have a dependence of t0.40±0.05 on the austempering time t, which evidences that diffusion of carbon has taken place. The kinetic parameter k determined using the Johnson-Mehl-Avrami equation has a maximum of 3.9×10−3 (s−1) at ≈623 K and corroborates that Mn slows the transformation rate.

A Stretched Exponential Law for the Average Time History of Gamma-Ray Bursts and Their Time Dilations

Individual gamma-ray bursts (GRBs) have very diverse time behavior—from a single pulse to a long complex sequence of chaotic pulses of different timescales. I studied time profiles of GRBs using data from the Compton Gamma Ray Observatory's Burst and Transient Source Experiment (BATSE) and found that the postpeak slope of the average peak-aligned time profile of GRBs obeys a unique and simple analytical law, I ~ exp [-(t/t0)1/3], where t is the time measured from the peak of the event and t0 is a constant ranging from 0.3 s for strong bursts to ~1 s for weak bursts. The average peak-aligned time profile follows this law with good accuracy in the whole time range available for analysis (from fractions of a second to ~120 s after the peak). Such a law (a stretched exponential) appears in processes associated with fractals (e.g., turbulence). The same analysis for solar flares gives a different shape for the average time profile. The dependence of t0 on the brightness of GRBs is presented. The time dilation of the dimmest GRBs relative to the brightest GRBs is at least a factor ~2 and possibly ~3. The statistics (600 GRBs), however, still does not allow us to rule out an intrinsic anticorrelation between intensity and duration of GRBs as a possible explanation of the effect. Probably, it is possible to confirm (or disprove) the cosmological origin of GRBs using the total existing statistics of strong bursts.

Radiation effects on the ablation of mass in laser-produced plasmas

The effect of x-ray radiation and transport on the ablated mass is considered in the computer simulation of laser-produced plasmas. Two regimes are identified. For times shorter than a critical time t0, the plasma is ‘‘classical,’’ in that the ablated mass computed when radiation effects are included is approximately the same as that when these effects are neglected. For longer times, however, the former is considerably larger than the latter. The dependence of t0 on the incident laser intensity and the influence of the laser wavelength and flux limiter used in the simulations are determined.

Near-ideal low threshold behavior in (111) oriented GaAs/AlGaAs quantum well lasers

Fundamental characteristics of (111) oriented GaAs/AlGaAs graded-index separate-confinement-heterostructure single quantum well lasers have been compared with conventional (100) oriented lasers. In particular, the threshold current density Jth of (111) oriented lasers does not change with the well width Lz in the range of Lz=30–100 Å, which corresponds to an ideal extreme. The lowest Jth of 145 A/cm2 together with a high characteristic temperature T0 of 186 K in the threshold-temperature dependence has been achieved for an Lz of 40 Å and a cavity length of 490 μm. The dependence of T0 on Lz showed that T0 is maximum at Lz∼60 Å for both (111) and (100) oriented lasers.

Determination of the steady temperature field in a toothed ring

An examination is made of a method of calculating the temperature field in the region illustrated in Fig. 1. The temperature T0 of the shaded heat regions is found, under the assumption that the shaded regions possess high thermal conductivity, and that the temperature is the same at all points of these regions. The method is applied to calculation of the temperature field in a phase shifter rotor. The dependence of T0 on the thickness of thermal insulation of the rotor conductors is given.