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A series of experiments were carried out on the parison formation stage in extrusion blow molding of high-density polyethylene (HDPE) under different die temperature, extrusion flow rate, and parison length. The drop time of parison when it reached a given length and its swells, including the diameter, thickness, and area swells, were determined by analyzing its video images. Two backpropagation (BP) artificial neural network models, one for predicting the length evolution of parison with its drop time, the other predicting the swells along the parison, were constructed based on the experimental data. Some modifications to the original BP algorithm were carried out to speed it up. The comparison of the predicted parison swells using the trained BP network models with the experimentally determined ones showed quite a good agreement between the two. The sum of squared error for the predictions is within 0.001. The prediction of the parison diameter and thickness distributions can be made online at any parison length or any parison drop time within a given range using the trained models. The predicted parison swells were analyzed.

Single-component tunable Li 2 Ca 4 Si 4 O 13 :Ce 3+ ,Tb 3+ ,Mn 2+ phosphors were successfully synthesized at 950 °C. Li 2 Ca 4 Si 4 O 13 :Ce 3+ ,Tb 3+ exhibits two luminescence peaking at 430 and 550 nm, which originated from the allowed 5d → 4f transition of the Ce 3+ ion and the 5 D 4 → 7 F J ( J = 6, 5, 4, 3) transition of the Tb 3+ ion, respectively. Moreover, by codoping Ce 3+ ions in the Li 2 Ca 4 Si 4 O 13 :Mn 2+ system, yellow-red emission from the forbidden transition of Mn 2+ could be enhanced. Under UV excitation, dual energy transfers (ETs), namely, Ce 3+ → Mn 2+ and Ce 3+ → Tb 3+ , are present in the Li 2 Ca 4 Si 4 O 13 :Ce 3+ ,Tb 3+ ,Mn 2+ system. The ET process was confirmed by the overlap of the excitation spectra, variations in the emission spectra, ET efficiency, and decay times of phosphors. In addition, quantum yields and CIE chromatic coordinates are presented. The emission color of these phosphors can be tuned precisely from blue to green via ET of Ce 3+ → Tb 3+ and from blue to yellow via ET of Ce 3+ → Mn 2+ . White light can also be achieved upon excitation of UV light by properly tuning the relative composition of Tb 3+ /Mn 2+ . This result indicates that the developed phosphor may be regarded as a good tunable emitting phosphor for UV light-emitting diodes.

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