Cost analysis of a two unit priority standby system with imperfect switch and arbitrary distributions

This paper deals with cost analysis of a single server two-unit (one priority and the other ordinary) cold standby system with two modes—normal and total failure. A switch is used to operate the standby unit (ordinary) and it works successfully with known probability p( = 1 ? q). Priority unit gets preference both for operation and repair. Failure and repair time distributions are arbitrary. System fails when switch or both the units fail totally. The system is observed at suitable regenerative epochs in order to obtain reliability characteristics of interest to system designers and operations managers. Explicit results for the exponential time distributions have been obtained in particular cases.     

A two-unit parallel redundant system with three modes and bivariate exponential lifetimes

A two-unit parallel redundant system is applicable in many practical fields, such as computer systems. Whereas the earlier models for such a system have assumed that the failures of the two units are independent, these are taken here to be dependent and have a joint bivariate exponential (BVE) distribution. Each unit has three modes and when the system fails completely, it is repaired (or replaced) with arbitrary rate. Using Sugasaw and Kaji's (Microelectronics and Reliability, 21 (5), 661–670) modification of the regenerative point technique as applied to Markov-renewal process theory, several reliability characteristics of interest to system designers are obtained.     

A two (multicomponent) unit parallel system with standby and common cause failure

This paper investigates the mathematical model of a system composed of two non-identical active parallel units and one cold standby. A unit has N components, each having a constant failure and repair rate. These vary from component to component. Several reliability characteristics of interest to system designers as well as operations managers have been computed. Results obtained earlier are verified as particular cases.     

Growth,characterizations, and the structural elucidation of diethyl-2-(3-oxoiso-1,3-dihydrobenzofuran-1-ylidene)malonate crystalline specimen for dielectric and electronic filters,thermal, optical,mechanical, and biomedical applications using conventional experimental and theoretical practices

Journal of Materials Science: Materials in Electronics - The single crystals of diethyl-2-(3-oxoiso-1,3-dihydrobenzofuran-1-ylidene) malonate (D23DYM) were grown successfully and efficiently by the...     

Effect of obstacle strength and spacing on the slope of Haasen plot

The rate sensitivity of multiple obstacle aluminium alloy system was measured using the stress relaxation method. A discrepancy was observed between the slope of the Haasen plot (rate sensitivity of dislocation–dislocation interaction) in pure metals and in alloys strengthened by multiple obstacles. Considering a simplifying assumption of the constant obstacle force–distance profile, it is suggested that slope of the Haasen plot is governed by glide dislocations’ length taking part in a thermally activated event. The relative strength and spacing of obstacles (forest dislocations, solutes and precipitates) is proposed to affect the thermally activated dislocation length, which in turn manifests as the difference in slope of the Haasen plot.     

Synthesis and spectroscopy of transparent colloidal solution of Gd2O3: Er3+, Yb3+ spherical nanocrystals by pulsed laser ablation

The synthesis and the spectroscopy of upconverting nanocolloidal solutions have recently generated considerable interest due to their potential application as biolevels and in biological assays. This paper reports the synthesis of lanthanides doped transparent colloidal solution via pulsed laser ablation (PLA) which is highly fluorescing. Er³⁺, Yb³⁺ co-doped Gd₂O₃ phosphor has been laser ablated to synthesize the colloidal solution in triply distilled water. Spherical shaped nanoparticles of the average diameter in the range of 8–26 nm have been synthesized and characterized. Efficient multicolor upconversion (UC) emission has been observed and possible UC mechanism has been suggested. This approach will provide a method to synthesize highly UC efficient, non-agglomerated, pure transparent nanocolloidal solution for biological applications from already reported efficient phosphors.     

Synthesis of K-doped p-type ZnO nanorods along (100) for ferroelectric and dielectric applications

Urchin-like p-type ZnO nanorods were grown along preferred (100) direction by low temperature solution technique and subjected to morphological, structural, Hall conductivity, dielectric and ferroelectric characterization. Hall voltage, bulk carrier density (hole) and mobility were found to be 0.058 V, 2.36 × 10¹⁹ cm⁻³ and 0.025 cm²/V s, respectively. In the temperature variation of the dielectric constant a phase transition at 343 K was observed at various frequencies. The piezoelectric charge coefficient (d₃₃) was found to be 1.60 pC/N. In the ferroelectric hysteresis loop studies, ZnO exhibited remnant polarization and coercive field at 0.083 µC/cm² and 3.86 kV/cm, respectively.     

Establishment of traceability for strain measuring data acquisition system in terms of voltage

This paper emphasizes on establishment of traceability for the strain measuring data acquisition system in terms of voltage. If this amplifier’s output voltage is not calibrated then traceability chain breaks. To complete the traceability chain, the amplifier’s output voltage has been calibrated for corresponding strain. The sensitivity is calculated using calibration results and further used to feed in data acquisition system to display the result in terms of force/strain.     

High Speed Imaging of Generation and Collapse of Multielectron Bubbles in Liquid Helium

We present experimental results on the generation and collapse of multielectron bubbles in liquid helium. By applying voltage pulses to a tungsten tip above the surface of the liquid, millimetre sized deformations were formed. Using high speed photography, we have imaged the disintegration of these deformations into bubbles of sizes ranging from ten to few hundred microns. At temperatures less than 2 K, the bubbles split into smaller bubbles and then disappeared in a time scale of few milliseconds. Smaller bubbles were formed at temperatures around 3 K, but were visible for more than hundreds of milliseconds. Although we have not been able to measure their charge directly, some of these bubbles responded to electric fields, implying these were indeed multielectron bubbles. With the existing theoretical picture, it is not possible to understand the strong dependence of the lifetime of multielectron bubbles on temperature.     

Coexistence of Superconductivity and Ferromagnetism

An overview of the problem of the coexistence of superconductivity and ferromagnetism in uranium-based superconductors such as UGe₂, URhGe, UCoGe, UIr and ZrZn₂ will be briefly presented. Starting with a pairing Hamiltonian with equal spin superconducting triplet pairs and using quantum field theory Green function formalism, the coexistent ferromagnetic order with superconductivity will be shown to be a very distinct possibility. The singlet superconductivity coexisting with ferromagnetism is against the experimental observations. It will be argued that the superconductivity can be destroyed at two points as a result of magnetic fields both intrinsic and or extrinsic, and thus establishing reentrant superconductivity as observed most recently in URhGe. In the absence of consensus on the mechanism, the same is not highlighted although the magnetic quantum fluctuations emanating from quantum critical point could provide the pairing. The limitations of the model will also be discussed.