Identifying prognostic indicators for electrical treeing in solid insulation through pulse sequence analysis

Predictive maintenance attempts to evaluate the condition of equipment and predict the future trend of the equipment's aging, in order to reduce costs when compared to the two traditional approaches: corrective and preventive maintenance. This prediction requires an accurate prognostic model of aging. In solid insulation, the ultimate goal of prognostics is to predict the advent of failure, i.e., insulation breakdown, in terms of remaining useful life (RUL). One fault is electrical treeing, which is progressive thus leading to potentially catastrophic failure. Research has shown that diagnosis of faults can be achieved based on partial discharge (PD) monitoring [1], i.e., phase-resolved and pulse sequence analysis (PSA). This work will explore the extension of this concept towards predicting evolution of the defect: moving beyond diagnostics towards prognostics. To do this, there is a need for further investigation of prognostic features within PD characteristics leading up to breakdown. In this work, a needle-plane test arrangement was set up using a hypodermic needle and pre-formed silicone rubber as test samples. The visual observations and tree growth measurements were made using a digital microscope. PD data was captured using a radio frequency (RF) sensor and analysed using PSA. The main idea of the PSA approach is the strong relationship between two consecutive pulses caused by PD activities, which can give an understanding of the local degradation processes [1]. As for electrical treeing, a breakdown indicator in PSA is the appearance of heavily clustered data points that lie diagonally in scatter plots of the differential ratio of voltage and time of consecutive charges (Un = Δun/Δtn) [2,3]. Figure 1 shows an example of a plot that changed to a diagonal line after 14 hours of aging time. This paper investigates the formation of the diagonal line based on the distribution of the plot from the start of electrical treeing until breakdown occurs. Finally, statistical features of the PSA plot are given and will be used for lifetime prediction of insulation samples in future work

Size versus truthfulness in the house allocation problem

We study the House Allocation problem (also known as the Assignment problem), i.e., the problem of allocating a set of objects among a set of agents, where each agent has ordinal preferences (possibly involving ties) over a subset of the objects. We focus on truthful mechanisms without monetary transfers for finding large Pareto optimal matchings. It is straightforward to show that no deterministic truthful mechanism can approximate a maximum cardinality Pareto optimal matching with ratio better than 2. We thus consider randomized mechanisms. We give a natural and explicit extension of the classical Random Serial Dictatorship Mechanism (RSDM) specifically for the House Allocation problem where preference lists can include ties. We thus obtain a universally truthful randomized mechanism for finding a Pareto optimal matching and show that it achieves an approximation ratio of eovere-1. The same bound holds even when agents have priorities (weights) and our goal is to find a maximum weight (as opposed to maximum cardinality) Pareto optimal matching. On the other hand we give a lower bound of 18 over 13 on the approximation ratio of any universally truthful Pareto optimal mechanism in settings with strict preferences. In the case that the mechanism must additionally be non-bossy, an improved lower bound of eovere-1 holds. This lower bound is tight given that RSDM for strict preference lists is non-bossy. We moreover interpret our problem in terms of the classical secretary problem and prove that our mechanism provides the best randomized strategy of the administrator who interviews the applicants

Kritik Sosial Dalam Novel Detik- Detik Cinta Menyentuh Karya Ali Shahab Sebuah Tinjauan Sosiologi Teks

Sesuai dengan permasalahan dalam penelitian ini, yaitu mengamati kritik sosial dalamkarya sastra, maka penelitian berhubungan erat dengan nilai-nilai yang ada dalammasyarakat. Karya sastra selalu erat kaitannya dengan faktor sosial, dalam hal inipemahaman mengenai keadaan sosial yang dimiliki oleh pengarang harus tinggi, karenasosiologi sastra harus berdasarkan dari pengamatan, Penelitian ini bertujuan untuk mengungkap kritik sosial yang terkandung dalam novelDetik-Detik Cinta Menyentuh karya Ali Shahab melalui pendekatan sosiologi sastra. Metodeyang digunakan dalam penelitian ini adalah metode deskriptif kualitatif, Analisis isi diperolehuntuk mengungkap dan mendeskripsikan unsur ekstrinsiknya. Penelitian ini juga bertujuanuntuk menjelaskan unsur-unsur struktur pembangun novel meliputi alur, penokohan, latarserta tema dan amanat Metode penelitian yang akan digunakan dalam penelitian ini adalah pendekatanstruktural dan pendekatan sosiologi karena seperti yang telah dipahami bahwa karya sastratidak terlepas dari pengarang, latar belakangnya, lingkungan masyarakatnya, dan kondisisosial pada saat karya tersebut ditulis. Adapun pendekatan sosiologi sastra adalah salah satupendekatan sastra yang memperhatikan keadaan sosial masyarakat dalam menelaah sebuahkarya sastra. Pendekatan struktural dapat menjelaskan unsur-unsur yang membangun maknatotalitas struktur novel Ada tiga kritik sosial yang terkandung dalam novel Detik-detik Cinta MenyentuhKarya Ali Shahab. Kritikan pertama adalah kritik terhadap kekuatan tirani yang menjadipenyebab kemiskinan dan kehancuran rumah tangga. Dalam novel ini, tokoh pemegangkekuasaan dan kekayaan tidak dapat menunjukan sikap bijaksana dan baik budi, bahkansering kali berperilaku sewenang-wenang. Kritikan kedua adalah kritik terhadap sikapotoriter kaum borjuis, kaum borjuis memang sudah lama dikenal karena gaya hidupnya yangmewah dan glamour, mereka selalu berlaku sewenang-wenang karena mereka merasamemiliki otoritas terhadap setiap individu yang berada disekitar mereka. Kritik ketiga adalah kritik terhadap masalah diskriminasi dalam kehidupan seharihari.Dapat disaksikan keberadaan para orang dengan kecacatan masih menemui berbagaihambatan dalam banyak hal, antara lain disebabkan belum dipahami dan dimengerti olehsebagian warga masyarakat tentang bagaimana kita berperilaku dan bergaul bersama orangdengan kecacatan. Dalam aspek pendidikan, pekerjaan dan aspek lainnya sering kali masihditemui adanya perlakuan-perlakuan diskriminatif terhadap mereka

Intervention initiative programme - pilot evaluation

The report presented here refers to the preliminary findings of the evaluation of the pilot project with a group of Level 4 Applied Criminology students. Whilst it is acknowledged that these findings have limited statistical significance due to the small number of participants in the pilot project, some important trends can still be identified in the answers provided

The Deepest Supernova Search is Realized in the Hubble Ultra Deep Field Survey

The Hubble Ultra Deep Field Survey has not only provided the deepest optical and near infrared views of universe, but has enabled a search for the most distant supernovae to z~2.2. We have found four supernovae by searching spans of integrations of the Ultra Deep Field and the Ultra Deep Field Parallels taken with the Hubble Space Telescope paired with the Advanced Camera for Surveys and the Near Infrared Multi Object Spectrometer. Interestingly, none of these supernovae were at z>1.4, despite the substantially increased sensitivity per unit area to such objects over the Great Observatories Origins Deep Survey. We present the optical photometric data for the four supernovae. We also show that the low frequency of Type Ia supernovae observed at z>1.4 is statistically consistent with current estimates of the global star formation history combined with the non-trivial assembly time of SN Ia progenitors.Comment: 24 pages (6 figures), submitted to the Astronomical Journa

Similarity Measure Development for Case-Based Reasoning- A Data-driven Approach

In this paper, we demonstrate a data-driven methodology for modelling the local similarity measures of various attributes in a dataset. We analyse the spread in the numerical attributes and estimate their distribution using polynomial function to showcase an approach for deriving strong initial value ranges of numerical attributes and use a non-overlapping distribution for categorical attributes such that the entire similarity range [0,1] is utilized. We use an open source dataset for demonstrating modelling and development of the similarity measures and will present a case-based reasoning (CBR) system that can be used to search for the most relevant similar cases

Longitudinal Intra- and Inter-individual variation in T-cell subsets of HIV-infected and uninfected men participating in the LA Multi-Center AIDS Cohort Study.

To assess the intra-individual and inter-individuals biological variation and the effect of aging on lymphocyte T-cells subsets.We assessed lymphocyte phenotypes (CD3, CD4, and CD8 T-cells) in 89 HIV-1-infected and 88 uninfected white non-Hispanic men every 6 months, to examine the biological variation for those measurements, and the average change in lymphocyte phenotype over 34 years.The markers showed significant intra-individuality in HIV-infected and uninfected individuals with index of individuality of <1.4. No mean changes were seen over the 34 years, with the exception of percentage CD4T-cells in HIV-uninfected individuals.In the pre-HAART era, HIV-infected individuals experienced an increase in mean absolute CD3 T-cell numbers (11.21 cells/μL, P = 0.02) and absolute CD8 T-cell numbers (34.57 cell/μl, P < .001), and in the percentage of CD8 T-cells (1.45%, P < .001) per year and a significant decrease in mean absolute CD4 T-cell numbers (23.68 cells/μl, P < .001) and in the percentage of CD4 T-cells (1.49%, P < .001) per year.In the post-HAART era, no changes in mean levels were observed in absolute CD3 T-cell count (P = .15) or percentage (P = .99). Significant decreases were seen in mean count (8.56 cells/μl, P < .001) and percentage (0.59%, P < .001) of CD8 T-cells, and increases in mean absolute count (10.72 cells/μl, P < .001) and percentage (0.47%, P < .001) of CD4 T-cells.With the exception of CD4 (%), no average changes per year were seen in lymphocyte phenotype of HIV-uninfected men. The results of coefficients of variation of intra and inter-individuals of this study can be useful for HIV-1 infection monitoring and in addition the observation could be a useful guide for intra- and inter-individual coefficient variations, and establishing quality goal studies of different blood biomarkers in healthy and other diseases

Surface Relaxation Mechanisms in the Morphological Equilibration of Crystal Surfaces

The phenomenology of surface relaxation below the roughening temperature TR is shown via kinetic Monte Carlo simulation to exhibit extremely non-classical behavior depending on (1) initial morphology and (2) kinetic rate laws for atom motion. However, within the temperature and size scale of our simulations there are several different mechanisms that operate. The “pinch-off” mechanism is seen to be operative for ripple relaxation employing i-kinetics. For ripple relaxation employing ∆i-kinetics, pinch-off is seen at short times. At long times, these particular surfaces spontaneously island, and then reduction of line tension drives relaxation. Reduction of line tension also drives relaxation of dimpled surfaces.Engineering and Applied Science

Spin-transfer switching and low-field precession in exchange-biased spin valve nano-pillars

Using a three-dimensional focused-ion beam lithography process we have fabricated nanopillar devices which show spin transfer torque switching at zero external magnetic fields. Under a small in-plane external bias field, a field-dependent peak in the differential resistance versus current is observed similar to that reported in asymmetrical nanopillar devices. This is interpreted as evidence for the low-field excitation of spin waves which in our case is attributed to a spin-scattering asymmetry enhanced by the IrMn exchange bias layer coupled to a relatively thin CoFe fixed layer.Comment: 11 pages, 4 figures. To appear in APL, April 200