3,525 research outputs found

    A Generalization of the Exponential-Poisson Distribution

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    The two-parameter distribution known as exponential-Poisson (EP) distribution, which has decreasing failure rate, was introduced by Kus (2007). In this paper we generalize the EP distribution and show that the failure rate of the new distribution can be decreasing or increasing. The failure rate can also be upside-down bathtub shaped. A comprehensive mathematical treatment of the new distribution is provided. We provide closed-form expressions for the density, cumulative distribution, survival and failure rate functions; we also obtain the density of the iith order statistic. We derive the rrth raw moment of the new distribution and also the moments of order statistics. Moreover, we discuss estimation by maximum likelihood and obtain an expression for Fisher's information matrix. Furthermore, expressions for the R\'enyi and Shannon entropies are given and estimation of the stress-strength parameter is discussed. Applications using two real data sets are presented

    Testing equality of variances in the analysis of repeated measurements

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    The problem of comparing the precisions of two instruments using repeated measurements can be cast as an extension of the Pitman-Morgan problem of testing equality of variances of a bivariate normal distribution. Hawkins (1981) decomposes the hypothesis of equal variances in this model into two subhypotheses for which simple tests exist. For the overall hypothesis he proposes to combine the tests of the subhypotheses using Fisher's method and empirically compares the component tests and their combination with the likelihood ratio test. In this paper an attempt is made to resolve some discrepancies and puzzling conclusions in Hawkins's study and to propose simple modifications.\ud \ud The new tests are compared to the tests discussed by Hawkins and to each other both in terms of the finite sample power (estimated by Monte Carlo simulation) and theoretically in terms of asymptotic relative efficiencies

    Self-Inverse and Exchangeable Random Variables

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    A random variable Z will be called self-inverse if it has the same distribution as its reciprocal 1/Z. It is shown that if Z is defined as a ratio, X/Y, of two rv's X and Y (with Pr[X=0]=Pr[Y=0]=0), then Z is self-inverse if and only if X and Y are (or can be chosen to be) exchangeable. In general, however, there may not exist iid X and Y in the ratio representation of Z.Comment: Statistics and Probability Letters (to appear, 6 pages

    IOT IN AGRICULTURE: PRECISION FARMING, CROP MONITORING, AND ENVIRONMENTAL SUSTAINABILITY

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    The main principle of this study is to discuss the importance of IoT in the agricultural field to maintain sustainability. IoT also plays an essential part in the crop monitoring process, therefore, with the aid of this technology crop health, and growth rates have to be monitored. Therefore, farmers are also capable of identifying the potential issue that has to be faced by this organization. Literature Review: Based on the research objectives, thematic analysis is highlighted in this section. This analysis helps to understand that, real-time data on various factors like moisture of the soil, humidity, temperature, as well as crop health, has to be collected with the aid of IoT sensors. Therefore, this information helps the farmers to make decisions about the farming process. Methodology: In this study, researchers are capable of collecting data with the support of various online sources. Therefore, ‚Äútheoretical analysis‚ÄĚ helps to analyze collected data. Deep conceptual understanding is promoted by this theoretical analysis. Findings: Valuable environmentally friendly data are collected by this IoT technology. Therefore, this information has a positive impact on the fertilization-related data. On the other hand, policy decisions like climate conditions, weather patterns, and pest infections help to maintain the sustainability of the agriculture field. Discussion: Overall discussion about this selected topic is highlighted in this section. Therefore, this section helps to understand that, IoT technology helps to monitor the crop health, and growth rates. Therefore, farmers are also capable of identifying the potential issue that has to be faced by this organization. The weather station of IoT helps to provide real-time data which helps the farmers to identify the present condition of the weather. Conclusion: The Impact of IoT in the agricultural field is discussed in this study. Therefore, with the aid of this study, it has to be noticed that, Implementing IoT technology in the agriculture field become expensive. Farmers in developing areas are unable to afford this technology. Therefore, it is noticed that cost is the main barrier to this advanced technology

    Some remarks on the van der Waerden conjecture

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    AbstractElementary proofs of the van der Waerden conjecture are given for the cases n=3 and n=4. Some partial results are found for the case n=5, and the conjecture is shown true for a special class of matrices

    On reciprocal symmetry

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    On the positive half line, there are two natural, and complementary, analogues of the single notion of symmetry of distributions on the real line. One is the R-symmetry recently proposed and investigated by Mudholkar and Wang [2007. IG-symmetry and R-symmetry: interrelations and applications to the inverse Gaussian theory. J. Statist. Plann. Inference 137, 3655‚Äď3671]; the other is the 'log-symmetry' investigated here. Log-symmetry can be thought of either in terms of a random variable having the same distribution as its reciprocal or as ordinary symmetry of the distribution of the logged random variable. Various properties, analogies, comparisons and consequences are investigated

    Control of composition and structure for molybdenum nitride films synthesized using ion beam assisted deposition

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    The purpose of the research described in this article was to synthesize molybdenum nitride films with well‚Äźdefined structures and stoichiometries using ion beam assisted deposition (IBAD). Approximately 400 nm thick films were prepared by the evaporative deposition of molybdenum while simultaneously bombarding the growing film with low energy (250‚Äď1000 eV) nitrogen ions. The effects of ion‚Äźto‚Äźatom arrival rate ratio, ion angle of incidence, and ion energy on the film composition and phase constituents were examined. The film nitrogen to molybdenum stoichiometry increased linearly with increasing arrival rate ratio irrespective of the ion energy and varied significantly with changes in the ion angle of incidence. The latter was interpreted based on sputtering and reflection effects. The phase constituents were functions of all of the deposition parameters investigated. We propose that a single parameter, the effective energy density per deposited atom, can account for the effects of ion energy, mass, and angle of incidence. The effective energy density is approximately the ion energy divided by the ion range. The range incorporates the effects of ion mass and angle of incidence, as well as the energy. For low energy ions the energy density per depositing atom is proportional to E1/2, a dependence that it shares with other models that have been developed to account for phase formation during IBAD. The advantage of the energy density treatment is that it has a more obvious influence on the temperature in the growth zone, a factor controlling phase formation. ¬© 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69720/2/JAPIAU-77-10-5138-1.pd

    Characterization and Modeling of 4H-SiC Low Voltage MOSFETs and Power MOSFETs

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    The integration of low voltage and high voltage circuits on SiC has profound applications. SiC power devices have proved their superiority in terms of high temperature operation, faster switching frequencies and larger power densities when compared with Si power devices. The control of SiC power devices however, lies in the hands of low voltage circuits built on Si. Thus, there exists a separation in the overall system between the low voltage and high voltage side, which increases system cost, weight and reduces efficiency. With the advancement in low voltage SiC processing technology, low voltage control circuits can be made on the same die as power devices, and power systems will become compact, robust and more efficient. A new low voltage process in 4H-SiC has been characterized and modeled. In order to design circuits with the low voltage process, designers need accurate device models for simulation. Currently, there exist no compact models in the public domain for low voltage SiC MOSFETs. This work aims at filling that void, by providing a modified PSP model for SiC MOSFETs. In addition, a new compact model for SiC power MOSFETs has also been developed and validated with characterization data from a commercially available 1200 V, 20 A power MOSFET. A gate driver chip has been designed and fabricated in 4H-SiC using the developed models. The gate driver chip will drive commercially available power MOSFETs in an integrated AC/DC converter application

    An anatomical-radiological study of the arteries of the distal extremity of the thoracic and pelvic limbs of the horse, ox, and dog

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