411 research outputs found

    Analisis Kelayakan Investasi Penambahan Mesin Frais Baru Pada CV. Xyz

    Full text link
    The rapid development of technology makes the world of industry must follow its development. Application of technology is expected to improve the production process so it can be produce a quality product. On the industrial manufacture of printing machines in CV XYZ, the machines have been used almost more than 20 years. There are indications that those machines passed the age lifetime. The alternatives that have been used during this time are the replacement of defective parts. Researchers wanted to compare these alternatives with the addition of a new milling machine. It required the addition of investment feasibility analysis of a new machine. The approximate period of 10 years and interest rates of 15% by using the NPV, the addition of milling machines attract Rp 461.201 million compared to replacement of defective parts of Rp 211.227 million. In contrast to the PBP and PI, the replacement of defective parts that are still ahead for 1 year 4 months and 4.2 compared to the addition of a new milling machine for 2 years and 1 month and 2.56. That can be concluded within 10 years, the alternative replacement of defective parts is still better than the addition of a new milling machine. However, for long-term investment it may be an alternative addition of a new milling machine more interesting

    Characterization of Fluctuations of Impedance and Scattering Matrices in Wave Chaotic Scattering

    Full text link
    In wave chaotic scattering, statistical fluctuations of the scattering matrix SS and the impedance matrix ZZ depend both on universal properties and on nonuniversal details of how the scatterer is coupled to external channels. This paper considers the impedance and scattering variance ratios, VRzVR_z and VRsVR_s, where VRz=Var[Zij]/{Var[Zii]Var[Zjj]}1/2VR_z=Var[Z_{ij}]/\{Var[Z_{ii}]Var[Z_{jj}] \}^{1/2}, VRs=Var[Sij]/{Var[Sii]Var[Sjj]}1/2VR_s=Var[S_{ij}]/\{Var[S_{ii}]Var[S_{jj}] \}^{1/2}, and Var[.]Var[.] denotes variance. VRzVR_z is shown to be a universal function of distributed losses within the scatterer. That is, VRzVR_z is independent of nonuniversal coupling details. This contrasts with VRsVR_s for which universality applies only in the large loss limit. Explicit results are given for VRzVR_z for time reversal symmetric and broken time reversal symmetric systems. Experimental tests of the theory are presented using data taken from scattering measurements on a chaotic microwave cavity.Comment: 6 pages, 5 figures, updated with referees' comment

    Chaotic Scattering in the Regime of Weakly Overlapping Resonances

    Full text link
    We measure the transmission and reflection amplitudes of microwaves in a resonator coupled to two antennas at room temperature in the regime of weakly overlapping resonances and in a frequency range of 3 to 16 GHz. Below 10.1 GHz the resonator simulates a chaotic quantum system. The distribution of the elements of the scattering matrix S is not Gaussian. The Fourier coefficients of S are used for a best fit of the autocorrelation function if S to a theoretical expression based on random--matrix theory. We find very good agreement below but not above 10.1 GHz

    Resonance trapping and saturation of decay widths

    Full text link
    Resonance trapping appears in open many-particle quantum systems at high level density when the coupling to the continuum of decay channels reaches a critical strength. Here a reorganization of the system takes place and a separation of different time scales appears. We investigate it under the influence of additional weakly coupled channels as well as by taking into account the real part of the coupling term between system and continuum. We observe a saturation of the mean width of the trapped states. Also the decay rates saturate as a function of the coupling strength. The mechanism of the saturation is studied in detail. In any case, the critical region of reorganization is enlarged. When the transmission coefficients for the different channels are different, the width distribution is broadened as compared to a chi_K^2 distribution where K is the number of channels. Resonance trapping takes place before the broad state overlaps regions beyond the extension of the spectrum of the closed system.Comment: 18 pages, 8 figures, accepted by Phys. Rev.

    Strain-induced partially flat band, helical snake states, and interface superconductivity in topological crystalline insulators

    Get PDF
    Topological crystalline insulators in IV-VI compounds host novel topological surface states consisting of multi-valley massless Dirac fermions at low energy. Here we show that strain generically acts as an effective gauge field on these Dirac fermions and creates pseudo-Landau orbitals without breaking time-reversal symmetry. We predict the realization of this phenomenon in IV-VI semiconductor heterostructures, due to a naturally occurring misfit dislocation array at the interface that produces a periodically varying strain field. Remarkably, the zero-energy Landau orbitals form a flat band in the vicinity of the Dirac point, and coexist with a network of snake states at higher energy. We propose that the high density of states of this flat band gives rise to interface superconductivity observed in IV-VI semiconductor multilayers at unusually high temperatures, with non-BCS behavior. Our work demonstrates a new route to altering macroscopic electronic properties to achieve a partially flat band, and paves the way for realizing novel correlated states of matter.Comment: Accepted by Nature Physic

    Nuclear Octupole Correlations and the Enhancement of Atomic Time-Reversal Violation

    Get PDF
    We examine the time-reversal-violating nuclear ``Schiff moment'' that induces electric dipole moments in atoms. After presenting a self-contained derivation of the form of the Schiff operator, we show that the distribution of Schiff strength, an important ingredient in the ground-state Schiff moment, is very different from the electric-dipole-strength distribution, with the Schiff moment receiving no strength from the giant dipole resonance in the Goldhaber-Teller model. We then present shell-model calculations in light nuclei that confirm the negligible role of the dipole resonance and show the Schiff strength to be strongly correlated with low-lying octupole strength. Next, we turn to heavy nuclei, examining recent arguments for the strong enhancement of Schiff moments in octupole-deformed nuclei over that of 199Hg, for example. We concur that there is a significant enhancement while pointing to effects neglected in previous work (both in the octupole-deformed nuclides and 199Hg) that may reduce it somewhat, and emphasizing the need for microscopic calculations to resolve the issue. Finally, we show that static octupole deformation is not essential for the development of collective Schiff moments; nuclei with strong octupole vibrations have them as well, and some could be exploited by experiment.Comment: 25 pages, 4 figures embedded in tex

    Measuring the Lyapunov exponent using quantum mechanics

    Full text link
    We study the time evolution of two wave packets prepared at the same initial state, but evolving under slightly different Hamiltonians. For chaotic systems, we determine the circumstances that lead to an exponential decay with time of the wave packet overlap function. We show that for sufficiently weak perturbations, the exponential decay follows a Fermi golden rule, while by making the difference between the two Hamiltonians larger, the characteristic exponential decay time becomes the Lyapunov exponent of the classical system. We illustrate our theoretical findings by investigating numerically the overlap decay function of a two-dimensional dynamical system.Comment: 9 pages, 6 figure

    Circulating Cell-Free DNA in Dogs with Mammary Tumors: Short and Long Fragments and Integrity Index

    Get PDF
    Circulating cell-free DNA (cfDNA) has been considered an interesting diagnostic/prognostic plasma biomarker in tumor-bearing subjects. In cancer patients, cfDNA can hypothetically derive from tumor necrosis/apoptosis, lysed circulating cells, and some yet unrevealed mechanisms of active release. This study aimed to preliminarily analyze cfDNA in dogs with canine mammary tumors (CMTs). Forty-four neoplastic, 17 non-neoplastic disease-bearing, and 15 healthy dogs were recruited. Necrosis and apoptosis were also assessed as potential source of cfDNA on 78 CMTs diagnosed from the 44 dogs. The cfDNA fragments and integrity index significantly differentiated neoplastic versus non-neoplastic dogs (P<0.05), and allowed the distinction between benign and malignant lesions (P<0.05). Even if without statistical significance, the amount of cfDNA was also affected by tumor necrosis and correlated with tumor size and apoptotic markers expression. A significant (P<0.01) increase of Bcl-2 in malignant tumors was observed, and in metastatic CMTs the evasion of apoptosis was also suggested. This study, therefore, provides evidence that cfDNA could be a diagnostic marker in dogs carrying mammary nodules suggesting that its potential application in early diagnostic procedures should be further investigated

    Gain Components in Autler-Townes Doublet from Quantum Interferences in Decay Channels

    Get PDF
    We consider non-degenerate pump-probe spectroscopy of V-systems under conditions such that interference among decay channels is important. We demonstrate how this interference can result in new gain features instead of the usual absorption features. We relate this gain to the existence of a new vacuum induced quasi-trapped-state. We further show how this also results in large refractive index with low absorption.Comment: Total 8 pages, 6 figures, submitted to Physical Review

    Signatures of the correlation hole in total and partial cross sections

    Full text link
    In a complex scattering system with few open channels, say a quantum dot with leads, the correlation properties of the poles of the scattering matrix are most directly related to the internal dynamics of the system. We may ask how to extract these properties from an analysis of cross sections. In general this is very difficult, if we leave the domain of isolated resonances. We propose to consider the cross correlation function of two different elastic or total cross sections. For these we can show numerically and to some extent also analytically a significant dependence on the correlations between the scattering poles. The difference between uncorrelated and strongly correlated poles is clearly visible, even for strongly overlapping resonances.Comment: 25 pages, 13 Postscript figures, typos corrected and references adde
    corecore