Abstract: A method for manufacturing methyltetrahydrophthalic anhydride is provided, which includes steps as follows. Maleic anhydride is added into a reactor. Piperylene is added into the reactor, so that the piperylene and the maleic anhydride undergo a first addition reaction. When a conversion rate of the maleic anhydride is more than 25%, the first addition reaction is completed. Isoprene is added into the reactor, so that the isoprene and the maleic anhydride undergo a second addition reaction to obtain a methyltetrahydrophthalic anhydride product. The methyltetrahydrophthalic anhydride product contains 3-methyltetrahydrophthalic anhydride and 4-methyltetrahydrophthalic anhydride.

Abstract: An optical system applied to an optical biometer is disclosed. The optical system includes a light source, first and second switchable reflectors, and first and second fixed reflectors. The first switchable reflector is disposed corresponding to the light source. The second switchable reflector is disposed corresponding to an eye. In a first mode, the first and second switchable reflectors are switched to a first state, and the incident light emitted by the light source is reflected by the first fixed reflector along a first optical path and then emitted to a first position of the eye. In a second mode, the first and second switchable reflectors are switched to a second state, and the incident light is sequentially reflected by the first switchable reflector, the second fixed reflector and the second switchable reflector along a second optical path and then emitted to a second position of the eye.

Abstract: A thermal compensation system for machine tools includes a thermal compensation-monitoring device and a cloud processing device. The thermal compensation-monitoring device receives a plurality of temperature signals of a workpiece and corresponding processing tolerance data to build or update a thermal compensation database. The cloud processing device provides a thermal compensation model, and applies the model with the characterized temperature signals and the tolerance data to generate a compensation value so as to decide whether or not to modify the model or to run a compensation is necessary.

Abstract: A fastening device for expansion cards that is capable of connecting to a slot on a normal motherboard and fastening an expansion card in the slot is disclosed. The fastening device includes a top pressing unit and two side fastening units, wherein the two side fastening units are connected to two ends of the top pressing unit, respectively, and each side fastening unit is provided with an opening. When two clip units disposed on the two ends of the slot pass through the openings of the two side fixing units respectively, the top pressing unit presses the top edge of the expansion card inserted into the slot and the two side fastening units respectively press and fasten the two clip units so as to restrain the clip units from unlocking and to prevent the expansion card from becoming loose in the slot.

Abstract: A fastening device for expansion cards that is capable of connecting to a slot on a normal motherboard and fastening an expansion card in the slot is disclosed. The fastening device includes a top pressing unit and two side fastening units, wherein the two side fastening units are connected to two ends of the top pressing unit, respectively, and each side fastening unit is provided with an opening. When two clip units disposed on the two ends of the slot pass through the openings of the two side fixing units respectively, the top pressing unit presses the top edge of the expansion card inserted into the slot and the two side fastening units respectively press and fasten the two clip units so as to restrain the clip units from unlocking and to prevent the expansion card from becoming loose in the slot.