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[en] CCD photometry in U, B, and V is presented for a 5' x 3' field in the globular cluster M15. The location of the main sequence in the color-magnitude diagram is found here to be significantly bluer than previous studies have indicated. The luminosity function of the cluster is studied down to V = 22.8 (Mroughly-equal7.5) and shown to be consistent with a power-law mass function, n(M) = QM/sup -alpha/ with α = 2.5 +- 1.0, to the limit of our data. The field star population brighter than V = 21.5, is examined in some detail. There appears to be about 50% more stars belonging to the disk in the field as compared with the Bahcall-Soneira standard galaxy model. The reddening to the cluster is found to be E(B-V) = 0.11 +- 0.04 from nine bright field stars. A new value for the ultraviolet excess of the cluster main-sequence stars is obtained, delta(0.6) = 0.25 +- 0.02, and confirms the well-known fact that M15 is among the metal poorest of the globular clusters
[en] A numerical analysis, backed by analytic solutions for some cases, is used to study the dependence of the base component of current gain and delay time in base implanted bipolar transistors on the base impurity profile. Results are presented in normalised form to facilitate their use in predicting device performance during the processing-device design stage. (author)
[en] In this paper, an approach for expanding the sampled area of a dynamic process by digital holography is reported, where angular, polarization and wavelength multiplexing are applied to record different regions of the sample on a series of sub-holograms overlapped in a single frame of the charge-coupled device. This approach based on a single exposure has special potential for the digital holographic recording of dynamic processes. (paper)
[en] A novel structure for designing and fabricating a power static induction transistor (SIT) with excellent high breakdown voltage performance is presented. The active region of the device is designed to be surrounded by a deep trench to cut off the various probable parasitical effects that may degrade the device performance, and to avoid the parallel-current effect in particular. Three ring-shape junctions (RSJ) are arranged around the gate junction to reduce the electric field intensity. It is important to achieve maximum gate-source breakdown voltage BVGS, gate-drain breakdown voltage BVGD and blocking voltage for high power application. A number of technological methods to increase BVGD and BVGS are presented. The BVGS of the power SIT has been increased to 110 V from a previous value of 50-60 V, and the performance of the power SIT has been greatly improved. The optimal distance between two adjacent ring-shape junctions and the trench depth for the maximum BVGS of the structure are also presented.
[en] A defect-tolerant design is presented for a demultiplexer circuit that is based on threshold logic. The design uses coding both to handle (i.e., tolerate) defects in the circuit and to improve the voltage margin in its gates. The following model is assumed for the defects: configured junctions can become either stuck open or stuck closed, and non-configured junctions can become shorted. Two realizations of the circuit are presented: one using conventional transistor circuitry, and the other using nanoscale components and wiring. The design presented in this paper demonstrates how a standard digital building-block circuit-a demultiplexer-can be efficiently protected against several types of defect simultaneously.
[en] This paper focuses on the design and optimization of different power P-channel LDMOS transistors (VBR > 120 V) to be integrated in a new generation of smart-power technology based upon a 0.18 µm SOI-CMOS technology. Different drift architectures have been envisaged in this work with the purpose of optimizing the transistor static (Ron-sp/VBR trade-off) and dynamic (Ron × Qg) characteristics to improve their switching performance. Conventional single-RESURF P-channel LUDMOS architectures on thin-SOI substrates show very poor Ron-sp/VBR trade-off due to their low RESURF effectiveness. Alternative drift configurations such as the addition of an N-type buried layer deep inside the SOI layer or the application of the superjunction concept by alternatively placing stacked P- and N-type pillars could highly improve the RESURF effectiveness and the P-channel device switching performance
[en] In this paper, the stability of static random access memory (SRAM) under the influence of statistical variability and bias temperature instability (BTI) induced ageing is investigated by statistical simulations. Effectively infinite and accurate compact models are successfully generated using ModelGenTM technology to prevent subsampling problem and ensure the statistical SRAM investigation, which successfully present device simulation results for circuits. The impact of transistor’s statistical variability on the SRAM stability is evaluated by SRAM static noise margin (SNM) sensitivity test. Three BTI induced ageing patterns of the SRAM cell are analysed at different ageing levels. The distribution, increase and decrease percentage of SNM is calculated at statistical level to show the combined effects of transistors’ variability with different ageing pattern. (paper)
[en] Two new Herbig-Haro objects, HH 132 and HH 133, have been discovered by CCD imagery behind interference filters on and just off the forbidden S II lines in the red. They are located in Puppis R2 and in Vela R2. Possible locations of their exciting sources are discussed. 12 refs
[en] Methods are discussed which have made it possible to measure radial velocities to within 1-3 km/s for O, B, and A spectral-type stars of all v sin i. The methods are based on the premise that neither the spectral type nor the rotation velocity of a star need be well known prior to the velocity measurement. This makes them particularly suitable for survey studies or programs dealing with very heterogeneous samples of early stars. Observations of early type members of the Pleiades and Alpha Persei open clusters at 3787 A shown that the radial-velocity zero point used here for the early type stars is consistent with that for late-type stars to about 1 km/s for all spectral types and projected rotation velocities. 25 refs