摘要:
A catalyst component for olefin polymerization comprising magnesium, titanium, halogen and electron donor, wherein the electron donor is selected from at least one of the diol diester compounds, when the diol diester comprised contains a certain amount of isomer with Fischer projection formula as shown in Formula (II), the activity and stereospecificity of the catalyst are greatly improved, especially in the production of polymers with high melt index, the isotactic index of the obtained polymers is improved substantially.
摘要:
A catalyst component for olefin polymerization comprising magnesium, titanium, halogen and electron donor, wherein the electron donor is selected from at least one of the diol diester compounds, when the diol diester comprised contains a certain amount of isomer with Fischer projection formula as shown in Formula (II), the activity and stereospecificity of the catalyst are greatly improved, especially in the production of polymers with high melt index, the isotactic index of the obtained polymers is improved substantially.
摘要:
A catalyst component for olefin polymerization which contains magnesium, titanium, halogen and electron donors is provided in the present invention. The electron donors are selected from at least one succinate compounds of following general formula (I), and the content of said succinate compounds with the structure as shown in Formula (II) in said succinate compounds (I) is less than 100%, but not less than 51.0 wt %. Compared with the mesomer whose content with the structure as shown in Formula (II) is 100%, the catalyst component provided by the present invention not only greatly decreases the manufacturing cost, but also improves certain properties of the catalyst, for example the molecular weight distribution of polymer obtained by catalytic reaction using said catalyst is wider, which is beneficial for improving processing properties of polymers. The corresponding catalyst is also provided.
摘要:
A circuit protection device includes a housing, which includes first and second electrodes. The device includes a conductive slider inside the housing. At a first location within the housing, the slider provides an electrical connection between the first and second electrodes. At a second location within the housing, the slider does not provide the electrical connection. A spring is secured to and stretched between the slider and an inner side of the housing such that the spring is held in tension in an expanded state. The slider is held at the first location by a solder between the slider and the first and second electrodes. After the device is armed, detection of an over-temperature condition causes the solder to begin to melt and the spring to compress and pull the slider to the second location within the housing, thus severing the electrical connection between the first and second electrodes.
摘要:
A reflowable thermal fuse includes a conduction element with first and second ends, disposed within a housing. The reflowable thermal fuse also includes an elastic element disposed within the housing and adapted to apply force on the conduction element in an activated state of the reflowable thermal fuse. A restraining element is utilized to secure the elastic element and prevent the elastic element from applying force on the conduction element in an installation state of the reflowable thermal fuse. Application of an activating current through the restraining element causes the restraining element to break and thereby release the elastic element and place the reflowable thermal fuse in the activated state.
摘要:
The disclosure discloses a method and an apparatus for determining a bias point of a modulator, wherein the method includes: adding pilot signals to the bias voltages of the modulator; adjusting the bias point of the modulator at a predetermined step and acquiring a first harmonic amplitude value corresponding to each bias point in a backlight detection current signal output by the modulator; and determining a bias point corresponding to the maximum value of the first harmonic amplitude values associated with multiple bias points as the bias point of the modulator. By virtue of the disclosure, the detection of a difference frequency signal can be eliminated, thereby reducing the complexity and cost of a periphery control circuit while ensuring the control accuracy, effectively improving the stability and reliability of the control process, and improving the modulation and transmission performance of optical signals in the whole system.
摘要:
A reflowable thermal fuse includes a positive-temperature-coefficient (PTC) device that defines a first end and a second end, a conduction element that defines a first end and a second end in electrical communication with the second end of the PTC device, and a restraining element that defines a first end in electrical communication with the first end of the PTC device and a second end, in electrical communication with a second end of the conduction element. The restraining element is adapted to prevent the conduction element from coming out of electrical communication with the PTC device in an installation state of the thermal fuse. During a fault condition, heat applied to the thermal fuse diverts current flowing between the first end of the PTC device and the second end of the conduction element to the restraining element, causing the restraining element to release the conduction element and activate the fuse.
摘要:
A processing technique and a composition which allow compositions of PBT polymers or copolymers to be formed into blow molded articles, especially medical balloons such as dilatation or stent placement balloons, from extruded tubular parisons. The process includes a longitudinal stretch step run at a temperature below the Tg of the polymeric material and a radial expansion step run at a temperature above the Tg of the polymeric material. During the longitudinal stretch step, the tubing is subjected to high internal pressure. In the composition a small amount of boric acid is added to the polybutylene terephthalate in a melt blend to give a formulation which has reduced crystallinity after extrusion and which can more readily fashioned into high strength blow molded articles than PBT by itself. Articles, which may be formed using the invention include medical device balloon articles in which the polymer consists essentially of PBT optionally blended with boric acid.
摘要:
Method and apparatus for controlling bias point of DQPSK demodulator are disclosed. The method comprises: step 1: respectively applying first and second bias voltages to I-path and Q-path, and applying identical pilot voltage signals to I-path and Q-path (S202); step 2: executing filtering processing on I-path and Q-path differential current signals collected by balance receiver and determining θIand θQ (S204); step 3: performing feedback control to first and second bias voltages respectively according to θI and θQ so that θI and θQ respectively reaches expected bias point values of I-path and Q-path (S206); executing step 2 and 3 cyclically at preset regular intervals (S208), so that θI and θQ remains consistently the expected bias point values of I-path and Q-path. The solution enables bias point of DQPSK demodulator to be locked at any expected bias point value, facilitates realization of digitization, and is not easily influenced.
摘要:
The disclosure discloses a method and an apparatus for determining a bias point of a modulator, wherein the method includes: adding pilot signals to the bias voltages of the modulator; adjusting the bias point of the modulator at a predetermined step and acquiring a first harmonic amplitude value corresponding to each bias point in a backlight detection current signal output by the modulator; and determining a bias point corresponding to the maximum value of the first harmonic amplitude values associated with multiple bias points as the bias point of the modulator. By virtue of the disclosure, the detection of a difference frequency signal can be eliminated, thereby reducing the complexity and cost of a periphery control circuit while ensuring the control accuracy, effectively improving the stability and reliability of the control process, and improving the modulation and transmission performance of optical signals in the whole system.