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This paper describes a method of measuring the glass transition temperature, by dynamic mechanical analysis, in which the glass transition temperature can be obtained by determining the temperature at which the peak value of damping is observed. The novelty of the method reported here is to use a fast heating technique with a feedback circuit that maintains the specimen at resonance. By doing the test in about a minute, polymer cure is not altered significantly by the heating cycle.

This article reported the temperature dependence of the electrical resistivity (ρ) of liquid Sn–3.5Ag lead-free solder alloy in continuous heating and cooling processes with varying Bi content in the range of 0, 2, 3.5, 5, and 7 wt.% Abnormal transitions can be observed on ρ–T curves, which indicate liquid–liquid structure transition (LLST) occurs in Sn–3.5Ag–xBi melts. Interestingly, unlike the pattern at first heating cycle, the LLST is reversible during subsequent cooling and heating cycles. Sn may play an important role on the reversibility, and Bi has a noticeable influence on the turning temperatures and characteristics during first heating cycle. The transition mechanism is analyzed from the viewpoint of short-range orders.

Rapid heating cycle moulding (RHCM) injection method can be used to solve many defects on the surface of the products produced by conventional injection method, such as weld mark, flow mark and so on. In this paper, the process of RHCM technology was presented. By comparing the new technology with the conventional injection method and the products produced by them, the advantages of RHCM technology were demonstrated. However, large warpage of the products was considered as the main defects of this technology. The reasons that caused the warpage of the products were analysed. Through finite element simulation and engineering experiment, the layout of the cold runners in the RHCM mould was optimised in order to decrease the warpage of the part. The results of the experiments and the finite element simulation were very close, proving that the simulation carried out in the paper was right.

D.C. four-probe method was used to investigate the temperature dependence of electrical resistivity of Sn–50wt%Sb melt. Anomalous changes observed on resistivity–temperature curves (ρ–T) suggest that temperature induced liquid–liquid structure transition (L-LST) might occur in Sn–50wt%Sb melt at hundreds of degrees above its liquidus, and the transition is reversible after the first heating cycle. An isothermal experiment based on ρ–T curve was conducted to further probe the effect of the L-LST on solidification morphologies. Results show that the size of the primary phase decreases and that the microstructure becomes finer when solidified from the melt experienced the irreversible L-LST.

Cold-rolled steel strips are annealed in batch annealing furnaces after coiling to release rolling residual stresses and to obtain desirable physical properties upon reaching recrystallization temperature. Simulation of coil behavior during heating cycle can be used to predict the temperature of coil middle points that cannot be measured directly so that furnace turn-off is properly scheduled. Using heat transfer equations and experimental data, a mathematical model of coil heating in hydrogen annealing furnaces was developed. This model is not only capable of predicting temperature distribution of all coil under various annealing conditions, but can also be used to design the heating cycles in a manner that all the constraints on temperature differences within coils are satisfied. Experiments confirmed the accuracy of the model in terms of its temperature predictive power and heating cycle scheduling capability.

Cold rolled coils are subjected to the annealing process in order to improve their formability and mechanical properties. A mathematical model of thermal behavior of coils during the heating cycle has been developed. Based on experimental data from several tests, the accuracy of the model has been confirmed. This model enables us to determine the coldest point of coils and the end time of furnace operation. Furthermore, the model has been used to analyze the effect of strip thickness on the heating time required. Thinner strips lead to prolonged heating time and larger temperature differences within the coil.

Steel strip coils need to be annealed after they leave the cold-rolling process. The purpose of annealing is to improve steel strip formability and to remove residual internal stresses imparted during rolling. Simultaneous increase of circulation rate and inert gas hydrogen content may have considerable effects on reducing the annealing process time. A mathematical model was developed to obtain a more accurate evaluation of the effects of these two parameters on heating and cooling cycles in the annealing process. The results from the simulation of an ordinary annealing process by the proposed model were compared with values measured at site and the accuracy of the model was confirmed. Finally, the effects of increasing hydrogen content and circulation rate were investigated, first independently from each other and then simultaneously. The predictions by the model showed that reduction of annealing time would be considerable when both parameters were simultaneously increased.

Batch annealing characterized by a long heating cycle and low heating temperature is widely used to produce sheet steels including interstitial-free (IF) steels. Optimizing batch-annealing conditio...

In order to optimize the heating duty cycle of the local hyperthermia applicators, we propose the dual frequency applicator instead of the well used single frequency applicator; it can be obtained by implementing the MW aperture source (axial or circumferential operating at 915 MHz) at the surface of the shortwave concentric loop (i.e., the magnetrode operating at 27.12 MHz). The numerical results on a simulated biological tissue show that this dual frequency applicator (or the coupled discrete oscillator) is able to enhance the penetration depth and also able to reduce the treatment period and the side effects such as the overheat of the subcutaneous normal tissue.

Engineering development of false-twist crimping machinery has made possible very high speeds of operation. However, it is found that practical speeds are limited by the heat-setting part of the process. This may be due to one of two things, either the time required for the yarn cross-section to reach a uniform temperature, or the time required for internal molecular rearrangement to take place. By measuring the thermal properties of highly twisted nylon yarns and the surface temperature of such yarns as a function of time, the internal temperature distribution of the yarn may be calculated at all times throughout the heating cycle. It is shown that the temperature within the yarn iS very nearly uniform at all stages of heating, and heat-transfer coefficients are calculated. It is concluded that the speed-limiting process is that of molecular rearrangement, and not that of heat-conduction.

Surface temperature patterns of foods being heated in a microwave oven were determined by infra-red television through a screen door permeable to IR radiation but not to microwaves. Isothermic patterns of the entire food surface exposed could be followed continuously during the heating cycle and photographed at a maximum rate of eight exposures per second. The method may prove useful in the development of microwave ovens to study the effects of oven and sample configuration, couplings, etc., on the field and temperature distribution, and further study seems justified to overcome present limitations.