We have developed a cold chopper system for mid-infrared observations. This system is installed into the newly developing mid-infrared instrument, MAX38, for the University of Tokyo Atacama 1.0-m telescope. It is cooled to about 9K. The cold chopper mirror is controlled by a piezoelectric actuator with a flexure hinge lever, and enables square-wave chopping at a frequency up to 7.8 Hz. At the m...

This paper presents considerations on the switching frequency and duty cycle & operating equations of softswitching BUCK chopper. These considerations are discussed and applied to selected soft-switching families such as ZVS-QRC, ZCS-QRC, ZVS-QSW-CV, ZCS-QSWCC, ZVT-PWM and ZCT-PWM [1]. The limitations on switching frequency and duty cycle are derived in terms of: chopper input voltage (Vg), cho...

This paper proposes a three-phase AC chopper system for the interconnection of various distributed generation (DG) farms or main utilities to enhance the active and reactive power flow control. The absence of large energy storage component in direct AC-AC converter makes the system footprint small and reliable. As the interface for different AC sources, the presented converter can be configured...

A new type of fast beam chopper was developed and installed at the HIMAC facility. Test operations of the chopper have been carried out. The chopper is basically a periodic beam-energy transformer that performs 10% modulation of beam’s kinetic energy. The modulated fraction of the beam is chopped off by the downstream RFQ due to the relatively narrow injection energy window of the RFQ. Some of ...

in this research, the isolated microspore culture system in 15 rose cultivars was tested. in the first experiment, the effect of rose cultivars on microspore viability and multicellular formation was examined. results showed that the most multicellular structures obtained in ‘apollo’, ‘amarosa’, ‘majic’, ‘candy’, ‘exotic’ and ‘velvet’ varieties. in the second experiment, the effect of various i...

Due to the decade of fossil fuels at present renewable energy plays an important role in generating power to meet the load requirements. Power produced from the renewable energy is very low. So chopper circuit is required to boost the voltage level of renewable energy sources. Chopper is a circuit in which fixed DC voltage is converted into variable voltage. There are many types of chopper circ...

A current noise reduction technique in chopper instrumentation amplifier (CIA) for high-impedance sensor is presented. The proposed technique is based on a time gating method to reduce time varying shot noise which is induced by channel charge injection of chopper switch transistors. An implemented CIA with the proposed time gating technique achieves more than 80-% noise reduction capability.

We report evidence of mode-locking to the envelope of a periodic stimulus in chopper units of the ventral cochlear nucleus (VCN). Mode-locking is a generalized description of how responses in periodically forced nonlinear systems can be closely linked to the input envelope, while showing temporal patterns of higher order than seen during pure phase-locking. Re-analyzing a previously unpublished...