Large-mode-area leaky optical fiber fabricated by MCVD

A large-mode-area single-mode optical fiber based on leaky-mode filtering was prepared by a modified chemical vapor deposition (MCVD) technique. The fiber has a leaky cladding that discriminates the fundamental mode from higher-order modes. A preliminary version has a 25 μm core diameter and 0.11 numerical aperture. A Gaussian-like mode with 22 μm mode field diameter was observed after 3 m propagation, in agreement with modeling.     

Effects of Steam Environment on Fatigue Behavior of Two SiC/[SiC+Si<Subscript>3</Subscript>N<Subscript>4</Subscript>] Ceramic Composites at 1300°C

The fatigue behaviors of two SiC/[SiC+Si₃N₄] ceramic matrix composites (CMC) were investigated at 1,300°C in laboratory air and in steam. Composites consisted of a crystalline [SiC+Si₃N₄] matrix reinforced with either Sylramic™ or Sylramic-iBN fibers (treated Sylramic™ fibers that possess an in situ BN coating) woven in a five-harness satin weave fabric and coated with a proprietary boron-containing dual-layer interphase. The tensile stress–strain behaviors were investigated and the tensile properties measured at 1,300°C. Tension–tension fatigue behaviors of both CMCs were studied for fatigue stresses ranging from 100 to 180 MPa. The fatigue limit (based on a run-out condition of 2 × 10⁵ cycles) in both air and steam was 100 MPa for the CMC containing Sylramic™ fibers and 140 MPa for the CMC reinforced with Sylramic-iBN fibers. At higher fatigue stresses, the presence of steam caused noticeable degradation in fatigue performance of both composites. The retained strength and modulus of all run-out specimens were characterized. The materials tested in air retained 100% of their tensile strength, while the materials tested in steam retained only about 90% of their tensile strength.     

Attributes of the latex emulsion processing and its role in morphology and performance in paints

This article explores the influence of process variation and neutralization of itaconic acid (IA) on polymer properties and paint performance. The study elaborated how the reaction pathway changes the acid distribution in the latexes. The study also investigated the influence on paint performance of degree of neutralization of IA before its incorporation into emulsion. The acid distribution study was done through the conductometric titration method. Latex film properties were studied through differential scanning calorimeter (DSC) and minimum film forming temperature (MFFT). These latexes were formulated in the corresponding paint and study was done using scanning electron microscopy (SEM), which was further correlated with the performance properties of the paint such as scrub, gloss, whiteness and contrast ratio.     

Modeling for bridging faults in nMOS combinational circuits

A transistor level model that fully describes the logical behavior of a circuit in the presence of bridging faults is presented for the nMOS combinational circuits. The proposed model is suitable for the circuits having static enhancement/depletion (E/D) load. Thus, the model can be applied to circuits like pseudo nMOS and CMOS non-threshold-logic (NTL). The model employs a logic transistor function (LTF) to examine the behavior of such circuits. The LTF model developed earlier for stuck faults in nMOS circuits is extended for bridging faults. Algorithms that were developed for the stuck faults in pseudo nMOS combinational circuits can be applied to generate the test vectors for bridging faults.     

VARIABILITY IN ASSEMBLY AND COMPETING SYSTEMS: EFFECT ON PERFORMANCE AND RECOVERY

We examine the effect of variability on the performance of an assembly system where two stations feed another station and a competing system where two independent stations are fed by a single station. We study the impact of variability in processing times, variability due to unreliable workstations, and variability due to imperfect yield. The above impact is examined for both PUSH and PULL manufacturing environments. We also discuss design features of the two configurations that could be used to recover part of the output lost due to variability.     

Antifeedant activity of quassinoids

The antifeedant activity of 13 quassinoids of different structural types has been studied against the Mexican bean beetle (Epilachna varivestis Mulsant) 4th instar larvae and the southern armyworm (Spodoptera eridania Crawer) 5th instar larvae. All quassinoids tested displayed significant activity against the Mexican bean beetle and, thus, do not reveal a simple structure-activity relationship. Five quassinoids were active against the southern armyworm. Interestingly, four of these-bruceantin (I), glaucarubinone (VI), isobruceine A (VIII), and simalikalactone D (XI)-possess the required structural features for antineoplastic activity. The noncytotoxic quassin (X) is an exception; it is active against both pests.     

Power-constrained testing for bridging and stuck short faults in CMOS combinational circuits

An increasing demand for the portable applications has elevated power consumption to be the most critical parameter. A transistor level model and a testing methodology are presented for detected bridging and stuck short faults in CMOS combinatorial circuits, with the power consumption as a major constraint during testing. The circuits are modeled by the CTF (Current Transfer Function) model. The quiescent current (IDDQ) measurement technique is utilized as the testing methodology. Transistor stuck open faults, that can change the test vector for IDDQ, are incorporated in the model. Simulation using hspice is carried out to support the results.