Profit Analysis of a Two Unit Cold Standby System Operating Under Different Weather Conditions Subject t o Inspection

A system, or unit, is said to be working under normal weather conditions if the system is working under prescribed conditions as defined/stated by the definition of reliability of system/unit, otherwise the system is said to be working in abnormal weather conditions. For example, if a car with the capacity for five persons is carrying more than five persons, it will be said to be working under abnormal weather conditions. Another example, if a hydraulic machine having the capacity to lift a maximum weight of 500 tons is lifting a weight of 600 tons, then the machine is working under abnormal weather conditions. Hence, in this situation, work done by the machine is out of its capacity and the machine is working in abnormal weather conditions. If the machine is working within the capacity of the stated conditions, it is said to be working in normal weather conditions. The main purpose of this paper is to analyze the profit of a two-unit system called the standby system that is working under different weather conditions in an inspection facility. There is a single perfect server who visits the system immediately whenever required. A server inspects the unit before repair/replacement of the failed unit. All the mechanical activities done by the server are only possible during normal weather conditions. There are two possibilities after inspection of the unit; either repair of the unit is feasible or not feasible. If repair of the unit is not feasible, then the unit will be replaced immediately by a new unit. Otherwise, the repaired unit works as a new unit. The operative unit undergoes preventive maintenance after a specific (maximum) operation time. All random variables are statistically independent. The failure rate and the rate by which the system undergoes for preventive maintenance are constant whereas the inspection rate, repair rate, and maintenance rate follow negative exponential distributions. The expressions for several reliability measures are derived in steady state conditions using the regenerative point technique and semi-Markov process. The graphical behavior of MTSF, availability and profit function, has been depicted with respect to preventive maintenance rate for arbitrary values of other parameters and costs

Enhanced superconducting properties of rare-earth oxides and graphene oxide added MgB₂

In this paper, the effects of addition of (i) graphene oxide (GO), (ii) a series of rare-earth (RE, RE = La, Sm, Eu, Gd, Tb and Ho) oxides (REO) and (iii) a mixture of GO and rare-earth oxides (GO + REO) on the superconducting properties of MgB₂, have been studied with the help of electrical transport and magnetic measurements. All the samples have been prepared following the standard solid-state reaction route. We have used an optimum value of 1 wt% REO and 3 wt% GO for addition on the basis of previous studies. X-ray diffraction studies confirm the formation of hexagonal crystal structure (space group P6/mmm) of MgB₂ with small amounts of REBx (x = 4 and 6) and MgO impurity phases in all the synthesized samples. We observe that the critical current density, Jc and upper critical field Hc2(0) improve significantly in the REO-added and GO-added samples with no significant change in critical temperature, Tc. A substantial enhancement in Jc(H) and Hc2(0) is observed with the GO + REO addition in MgB₂. The different flux pinning mechanisms in all the samples are studied and it is found that the point pinning is the dominant mechanism in the GO-added samples and grain boundary pinning is the dominant one in the REO added samples. We have seen the combined effect of both types of flux pinning mechanisms in GO + REO added MgB₂

Cost-Benefit Analysis of a Redundant System with Server having Refreshment Facility Subject to Inspection

In this paper two units cold standby system has been discussed with the facility that server inspect the failed unit before repair/replacement of the unit and server may allow to take refreshment whenever needed. The operative unit may fail directly from normal mode and the cold standby unit may be failed owing to remain unused for a longer period of time. There is single server who serves the dual purpose of inspection and repair immediately whenever required. Also, after having refreshment the server may eventually perform the better service efficiently. The time to take refreshment and repair activity follows negative exponential distribution whereas the distributions of unit failure and server failure are taken as arbitrary with different probability density functions. The expressions of various stochastic measures are analyzed in steady state using semi-Markov process and regenerative point technique. The graphs are sketched for arbitrary values of the parameters to delineate the behavior of some important performance measures to check the efficacy of the system model under such situations

Structural identification of two differently coordinated heptamolybdate ligands in a hexamagnesium compound

517-525Dissolution of freshly prepared molybdenum trioxide in hot aqueous magnesium carbonate followed by crystallization results in the formation of an all-inorganic heptamolybdate compound viz. [Mg(H2O)6]3[Mg(H2O)5(Mo7O24)][(H2O)5Mg (µ2-Mo7O24)Mg(H2O)5]∙6H2O (1). The crystal structure, spectral characteristics, thermal and electrochemical properties of 1 are reported. Compound 1, which crystallizes in the acentric polar space group Cc, contains six unique Mg(II) ions. The two crystallographically independent heptamolybdate anions function as a monodentate (η1) and µ2-bridging bidentate ligand, respectively, forming the anionic [Mg(H2O)5(Mo7O24)]4− and [(H2O)5Mg(µ2-Mo7O24)Mg(H2O)5]2− species, which are charge balanced by three unique hexaaquamagnesium(II) cations. The electrochemical and conductivity studies of 1 reveal the presence of [Mg(H2O)6]2+ cations and uncoordinated (Mo7O24)6− anions in solution. Thermal decomposition of 1 leads to the formation of Mg2Mo3O11 via Mg6Mo14O48 and 3Mg2Mo3O11∙5MoO3

Enhanced production of poly (3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer with manipulated variables and its properties

Cupriavidus sp. USMAA1020, a local isolate was able to biosynthesis poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer with various 4HB precursors as the sole carbon source. Manipulation of the culture conditions such as cell concentration, phosphate ratio and culture aeration significantly affected the synthesis of P(3HB-co-4HB) copolymer and 4HB composition. P(3HB-co-4HB) copolymer with 4HB compositions ranging from 23 to 75 mol% 4HB with various mechanical and thermal properties were successfully produced by varying the medium aeration. The physical and mechanical properties of P(3HB-co-4HB) copolymers were characterized by NMR spectroscopy, gel-permeation chromatography, tensile test, and differential scanning calorimetry. The number-average molecular weights (M (n)) of copolymers ranged from 260 x 10(3) to 590 x 10(3)Da, and the polydispersities (M (w)/M (n)) were between 1.8 and 3.0. Increases in the 4HB composition lowered the molecular weight of these copolymers. In addition, the increase in 4HB composition affected the randomness of copolymer, melting temperature (T (m)), glass transition temperature (T (g)), tensile strength, and elongation to break. Enzymatic degradation of P(3HB-co-4HB) films with an extracellular depolymerase from Ochrobactrum sp. DP5 showed that the degradation rate increased proportionally with time as the 4HB fraction increased from 17 to 50 mol% but were much lower with higher 4HB fraction. Degradation of P(3HB-co-4HB) films with lipase from Chromobacterium viscosum exhibited highest degradation rate at 75 mol% 4HB. The biocompatibility of P(3HB-co-4HB) copolymers were evaluated and these copolymers have been shown to support the growth and proliferation of fibroblast cells

Temperature-dependent transformation of the magnetic excitation spectrum on approaching superconductivity in Fe1-x (Ni/Cu)x Te0.5 Se0.5

Spin excitations are one of the top candidates for mediating electron pairing in unconventional superconductors. Their coupling to superconductivity is evident in a large number of systems, by the observation of an abrupt redistribution of magnetic spectral weight at the superconducting transition temperature, Tc, for energies comparable to the superconducting gap. Here we report inelastic neutron scattering measurements on Fe-based superconductors, Fe1-x (Ni/Cu)x Te0.5 Se0.5, that emphasize an additional signature. The overall shape of the low energy magnetic dispersion changes from two incommensurate vertical columns at T >> Tc to a distinctly different U-shaped dispersion at low temperature. Importantly, this spectral reconstruction is apparent for temperature up to ~3Tc. If the magnetic excitations are involved in the pairing mechanism, their surprising modification on the approach to Tc demonstrates that strong interactions are involved

Synthesis and structure of a mixed ligand copper(II) compound based on a distorted {CuN2O3} square pyramid

The synthesis, spectra, thermal study and crystal structure of a mixed ligand copper(II) compound viz. [Cu(biq)(acac)(NO3)] 1 (biq = 2,2′-biquinoline, acac = acetylacetonate) are reported. The {CuN2O3} coordination sphere is made up of two oxygen atoms of an unique acac ligand, an oxygen of the nitrate group and one N atom of biq ligand which form the basal plane {CuNO3} of a square pyramid. A second nitrogen atom of the biq ligand occupies the apical position resulting in a distorted square pyramidal {CuN2O3} polyhedron. In the crystal structure, each neutral square pyramidal copper(II) species is linked with two symmetry related molecules with the aid of intermolecular C-H×××O hydrogen bonding interactions. A study of fifteen mixed ligand copper(II) acetylacetonates reveals that in this series of compounds, 1 exhibits maximum deviation of the {CuN2O3} polyhedron from square pyramidal towards trigonal bipyramidal geometry.

Performance of community resources indicators for tourism development: a case study of Mah Meri community in Carey, Island, Malaysia

This paper presents the significant role of community resources which is utilized by the Mah Meri community in Pulau Carey, Malaysia to practice sustainable tourism. Mah Meri is one of the 18 indigenous tribes in Peninsular Malaysia that resides at Kampung Sungai Bumbon which is a well established indigenous tourism destination in Malaysia. Survey which was used as the qualitative data collection method helped the researchers to understand the community resources which can encourage sustainable tourism practice. Community resources consisting of cultural, natural, infrastructure, financial and human resources were tested. This study reveals that the community is proud of its natural and cultural resources. However, the community also feels that their tourism business is facing a threat because of scarcity of necessary natural resources. It is hoped that the findings of this study will contribute to existing literature in the indigenous tourism ground that could improve the sector into a more beneficial source of income for the indigenous community

Synthesis and structure of a mixed ligand copper(II) compound based on a distorted {CuN2O3} square pyramid

499-505The synthesis, spectra, thermal study and crystal structure of a mixed ligand copper(II) compound viz. [Cu(biq)(acac)(NO3)] 1 (biq = 2,2′-biquinoline, acac = acetylacetonate) are reported. The {CuN2O3} coordination sphere is made up of two oxygen atoms of an unique acac ligand, an oxygen of the nitrate group and one N atom of biq ligand which form the basal plane {CuNO3} of a square pyramid. A second nitrogen atom of the biq ligand occupies the apical position resulting in a distorted square pyramidal {CuN2O3} polyhedron. In the crystal structure, each neutral square pyramidal copper(II) species is linked with two symmetry related molecules with the aid of intermolecular C-H...O hydrogen bonding interactions. A study of fifteen mixed ligand copper(II) acetylacetonates reveals that in this series of compounds, 1 exhibits maximum deviation of the {CuN2O3} polyhedron from square pyramidal towards trigonal bipyramidal geometry

Strengthening traditional competenciesof Mah Meri community for indigenous tourism service performance

This paper presents the perception of the indigenous community on tourism development in their area. This study was conducted at Kampung Sungai Bumbon, Carey Island, Selangor populated by the Mah Meri community. Naturalistic inquiry which was used as the qualitative data collection method helped the researchers to understand the host-tourism relationship before conducting further investigation. The findings show that the traditional competencies are important for sustainable community development. The community also revealed that the outsiders’ influence is highly significant for the village to run the tourism activities successfully. However, the community feels that their culture and tourism business has been exploited by outsiders. The findings of this study will contribute to existing literature in the indigenous tourism field that could enhance the sector into a more profitable business for the indigenous communities in Malaysia