Physical Stabilization of the β→γ Transformation in Dicalcium Silicate

It has been shown that the monoclinic β -phase of dicalcium silicate (Ca₂SiO₄) can be stabilized against transformation to the orthorhombic γ -phase by physical rather than chemical factors. Stabilization was studied in different types of microstructures fabricated under various processing conditions such as different powder or grain sizes, chemical additives, cooling kinetics, or high-temperature annealing treatments. The observations can be explained in terms of a critical particle size effect controlling nucleation of the transformation. Rapid quenching through the high-temperature hexagonal ( α ) to orthorhombic ( a' _H) transformation at 1425°C, which is accompanied by a −4.7% volume decrease, causes periodic fracture of β -twins due to accumulated strains. Chemical doping with K₂O or Al₂O₃ promotes the formation of amorphous phases which mold themselves around β -Ca₂SiO₄ grains. Annealing treatments cause crystallization of the glass and subsequent transformation to the γ -phase.     

WDM experiment using 1300/1500 nm dual-wavelength LED for single-mode fibre transmission systems

A wavelength-division-multiplexing transmission experiment using a 1300/1500 nm dual-wavelength LED modulated at 140/560 Mbit/s over 10 km of single-mode fibre has been demonstrated. This dual-LED device has a 9 ?m emitter spacing between the active facets with a coupling loss of 2.3 dB through a lens/fibre coupler. The chromatic dispersion penalty for the 1500 nm channel at 560 Mbit/s was about 6-5 dB and the electrical crosstalk penalty was 2.5 dB.     

Finite-dimensional solutions of a modified Zakai equation

In risk-sensitive control a modified Zakai equation arises which includes an extra term related to the exponential running cost. We show that a wide class of finite-dimensional solutions related to the Beneš filter is possible as long as nonlinearities in the drift are canceled in an appropriate way by terms in the running cost. The support of NSERC Grant A7964 is gratefully acknowledged.     

High-precision curvature-compensated CMOS band-gap voltage and current references

Precise CMOS band-gap voltage and current references which uses the difference of MOS source-gate voltages to perform efficient curvature compensation are proposed and analyzed. Applying the developed design strategies, band-gap voltage references (BVR) with a temperature drift below 10 ppm/°C and a power-supply drift below 10 ppm/V can be realized. For band-gap current references, both drifts can be under 15 ppm. Experimental BVR chip shows an average drift of 5.5 ppm/°C from -60°C to 150°C and 25 V/V for supply voltages from 5 to 15 V at 25°C. Due to the use of the novel curvature-compensation technique, the circuit structure of the proposed references is simple and both chip area and power consumption are small.This research was supported by the National Science Council, ROC under contract NSC79-0404-E009-30.     

High permeability nano-crystalline FeSiBTaAg ribbons obtained by direct casting

Nano-crystalline soft magnetic ribbons, being extensively used as magnetic cores for switching power supplies, have been invariantly obtained by melt-spinning followed by post-annealing. Reported herewith are the attainment, by direct-casting without annealing, of nano-crystalline Fe_77.4−xSi_15.5B₇Ta_xAg_0.1 (x = 1, 2) ribbons with superior soft magnetic properties (named TAGMET after the addition of Ta and Ag). The grain size of nano-crystalline -FeSi, from 20 to 30 nm, varies with composition and quenching speeds. As-spun Fe_75.4Si_15.5B₇Ta₂Ag_0.1 ribbons consisting of 25 nm nano-crystals exhibit a saturation magnetization of 157 emu/g (1.45 T), an effective permeability of 56,000 at 1 kHz, and coercivity, 8 A/m. With the combination of easier manufacturing process and excellent soft magnetic properties, this alloy is competitive in industrial applications versus the well-known FINEMET.     

Novel interneuron having hybrid modulatory-central pattern generator properties in the feeding system of the snail, Lymnaea stagnalis

1. We used intracellular recording techniques to examine the role of a novel type of protraction phase interneuron, the lateral N1 (N1L) in the feeding system of the snail Lymnaea stagnalis. 2. The N1Ls are a bilaterally symmetrical pair of electrotonically coupled interneurons located in the buccal ganglia. Each N1L sends a single axon to the contralateral buccal ganglia. Their neurite processes are confined to the buccal neuropile. 3. In the isolated CNS, depolarization of an N1L is capable of driving a full (N1-->N2-->N3), fast (1 cycle every 5 s) fictive feeding rhythm. This was unlike the previously described N1 medial (N1M) central pattern generator (CPG) interneurons that were only capable of driving a slow, irregular rhythm. Attempts to control the frequency of the fictive feeding rhythm by injecting varying amounts of steady current into the N1Ls were unsuccessful. This contrasts with a modulatory neuron, the slow oscillator (SO), that has very similar firing patterns to the N1Ls, but where the frequency of the rhythm depends on the level of injected current. 4. The N1Ls' ability to drive a fictive feeding rhythm in the isolated preparation was due to their strong, monosynaptic excitatory chemical connection with the N1M CPG interneurons. Bursts of spikes in the N1Ls generated summating excitatory postsynaptic potentials (EPSPs) in the N1Ms to drive them to firing. The SO excited the N1M cells in a similar way, but the EPSPs are strongly facilitatory, unlike the N1L-->N1M connection. 5. Fast (1 cycle every 5 s) fictive feeding rhythms driven by the N1L occurred in the absence of spike activity in the SO modulatory neuron. In contrast, the N1L was usually active in SO-driven rhythms. 6. The ability of the SO to drive the N1L was due to strong electrotonic coupling, SO-->N1L. The weaker coupling in the opposite direction, N1L-->SO, did not allow the N1L to drive the SO. 7. Experiments on semintact lip-brain preparations allowed fictive feeding to be evoked by application of 0.1 M sucrose to the lips (mimicking the normal sensory input) rather than by injection of depolarizing current. Rhythmic bursting, characteristic of fictive feeding, began in both the SO and N1L at exactly the same time, indicating that these two cell types are activated in "parallel" to drive the feeding rhythm. 8. The N1L is also part of the CPG network. It Excited the N2s and inhibited the N3 phasic (N3p) and N3 tonic (N3t) CPG interneurons like the N1Ms.(ABSTRACT TRUNCATED AT 400 WORDS)     

Low-loss measurement in partially buried opticalwaveguideson glass with a plastic prism

Surface and buried planar waveguides have been fabricated in glass microscope slides with purely thermal potassium and sodium ion-exchange techniques. We measured propagation loss as low as 0.08 dB/cm in the partially buried waveguides using an improved two-prism coupling method. The method includes a plastic prism and involves applying heat to soften the base of the outcoupling plastic prism so that the prism is temporarily in extremely close contact with the waveguide surface.     

An independent three‐factor mutual authentication and key agreement scheme with privacy preserving for multiserver environment and a survey

In the past decades, the demand for remote mutual authentication and key agreement (MAKA) scheme with privacy preserving grows rapidly with the rise of the right to privacy and the development of wireless networks and Internet of Things (IoT). Numerous remote MAKA schemes are proposed for various purposes, and they have different properties. In this paper, we survey 49 three‐factor–based remote MAKA schemes with privacy preserving from 2013 to 2019. None of them can simultaneously achieve security, suitability for multiserver environments, user anonymity, user untraceability, table free, public key management free, and independent authentication. Therefore, we propose an efficient three‐factor MAKA scheme, which achieves all the properties. We propose a security model of a three‐factor–based MAKA scheme with user anonymity for multiserver environments and formally prove that our scheme is secure under the elliptic curve computational Diffie‐Hellman problem assumption, decisional bilinear Diffie‐Hellman problem assumption, and hash function assumption. We compare the proposed scheme to relevant schemes to show our contribution and also show that our scheme is sufficiently efficient for low‐power portable mobile devices.