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Nonlinear compression has become an obligatory technique along with the development of ultrafast lasers in generating ultrashort pulses with narrow pulse widths and high peak power. In particular, techniques of nonlinear compression have experienced a rapid progress as ytterbium (Yb)-doped lasers with pulse widths in the range from hundreds of femtoseconds to a few picoseconds have become mainstream laser tools for both scientific and industrial applications. Here, we report a simple and stable nonlinear pulse compression technique with high efficiency through cascaded filamentation in air followed by dispersion compensation. Pulses at a center wavelength of 1040 nm with millijoule pulse energy and 160 fs pulse width from a high-power Yb:CaAlGdO4 regenerative amplifier are compressed to 32 fs, with only 2.4% loss from the filamentation process. The compressed pulse has a stable output power with a root-mean-square variation of 0.2% over 1 hour.
It is difficult to generalize health technology assessment in the field of traditional Chinese medicine (TCM). The lack of an outcomes evaluation system based on TCM theory is one of the important reasons. Studies conducted in menstruating women have shown that the prevalence of primary dysmenorrhea varies from 45 to 95 percent. As a debilitating condition for many women, dysmenorrhea is one of the leading causes of absenteeism from school or work, which has a negative effect on quality of life (QoL). TCM has obvious advantages in treating dysmenorrhea. This study aimed to develop a dysmenorrhea QoL scale based on TCM theory.
We conducted focus group discussions and in-depth interviews with TCM gynecologists and patients, and adapted items from previously published scales. We generated an initial pool of forty-one items with eight domains. The Delphi method was used for preliminary item selection. Then, we administered the items to a sample of adolescent girls (n = 200). The distribution of survey items, discrete trend, factor analysis, correlation coefficient, and Cronbach's α coefficient were used to select items.
After two rounds of expert consultation, a total of thirty items were included in the dysmenorrhea QoL scale. And after sample analysis, four items' frequency distribution was skewed, five items' standard deviation (SD) was <0.8, four items' factor loading was <0.4, five items' score correlation coefficient with a related domain was <0.4, and three items’ deletion would cause their domain's Cronbach's α coefficient increased. The items were deleted when they met more than two above standards.
A total of twenty items with eight domains were included in the dysmenorrhea QoL scale. The methods to select the dysmenorrhea QoL scale items based on TCM theory were preferable. Given the paucity of research in this area, this new dysmenorrhea QoL scale may provide opportunities for patient-reported outcome evaluation in the field of TCM.
This paper provides a solution to the active vibration control of a microsatellite with two solar panels. At first, the microsatellite is processed as a finite element model containing a rigid body and two flexible bodies, according to the principles of mechanics, and that the dynamic characteristics are solved by modal analysis. Secondly, the equation involving vibration control is established according to the finite element calculation results. There are several actuators composed of macro fibre composite on the two solar panels for outputting control force. Furthermore, the control voltage for driving actuator is calculated by using fuzzy algorithm. It is clear that the smart structure consists of the flexible bodies and actuators. Finally, the closed-loop control simulation for suppressing harmful vibration is established. The simulation results illustrate that the responses to the external excitation are decreased significantly after adopting fuzzy control.
Ferroelectric random access memory (FeRAM) is believed to be the most promising candidate for the next generation non-volatile memory due to its fast access time and low power consumption. Fabrication technologies of FeRAM can be divided into two parts: CMOS technologies for circuits which are standard and can be shared with traditional IC process line, and process relating to ferroelectric which is separated with CMOS process and defined as backend module. This paper described technologies for integrating ferroelectric capacitors into standard CMOS, mainly about modeling of ferroelectric capacitors and backend fabrication technologies. Hysteresis loop of the ferroelectric capacitor is the basis for FeRAM to store data. Models to describe this characteristic are the key for the design of FeRAM. A transient behavioral ferroelectric capacitor model based on C-V relation for circuit simulation is developed. The arc tangent function is used to describe the hysteresis loop. “Negative capacitance” phenomenon at reversing points of applied voltage is analyzed and introduced to the model to describe transient behaviors of the capacitor. Compact equivalent circuits are introduced to integrate this model into HSPICE for circuit simulation. Ferroelectric materials fabrication, electrodes integration and etching are the main technologies of FeRAM fabrication process. An metal organic chemical vapor deposition (MOCVD) process is developed to fabricate high quality Pb(Zr1-xTix)O3 (PZT) films. Pt is known to cause the fatigue problems when used as electrodes with PZT. Ir is used as electrodes to improve the fatigue property of PZT based capacitors, and mechanism of the fatigue is analyzed. Hard mask is used to reduce the size of the capacitors and damage caused in etching process. In our process, Al2O3 is developed as hard mask, which simplifies the FeRAM backend integration process.
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