Open circuit fault detection and diagnosis in matrix converters

With the increased use of power electronics in aerospace, automotive, industrial, and energy generation sectors, the demand for highly reliable and power dense solutions has increased. Matrix converters become attractive when taking into account demands for high reliability and high power density. With their lack of large bulky DC-link capacitors, high power densities are possible with the capability to operate with high ambient temperatures. When a power converter needs high reliability, under tight weight and volume constraints, it is often not possible to have an entirely redundant system. Taking into account these constraints it is desirable that the power converter continue to operate even under faulty conditions, albeit with diminished performance in some regard. This paper presents an open circuit switch fault detection and diagnosis system for matrix converters, which has been experimentally validated. The presented system requires no load models, averaging windows or additional sensors, this makes the proposed method fast and low cost

Design of a high-force-density tubular motor

This paper deals with the design, construction and experimental verification of a high force density, tubular, linear, permanent magnet motor, driven from a high power density matrix converter for an aerospace application. The work also describes the implementation and experimental verification of a novel, thermal management technique for the phase windings of electrical machines. The technique introduces a higher thermal conductivity path between the centre of the slot and the cooling arrangement, thus increasing the heat flow away from the slot centre. An introduction to the design of the motor is first given, after which an introduction to the technique is presented. A study of how the implementation of the technique affects motor performance is then presented. A detailed overview of the construction aspects is highlighted and finally, experimental validation is used to illustrate the comparison between the predicted results and the measured results, obtained from an instrumented, test rig

Experimental comparison of a matrix converter using Si IGBT and SiC MOSFETs

This paper presents an analytical and experimental comparison between comparable Silicon (Si) IGBTs and Silicon Carbide (SiC) MOSFETS when used in a direct AC/AC matrix converter circuit. The switching performance of the two devices is analysed and the efficiency / losses measured in order to develop a loss model which will help engineers to design and develop matrix converter circuits using these types of devices. Particular attention is given in the paper to the discrepancies found between the data-sheet values and the measured data. The EMI performance of the two matrix converters is also determined and the implication of using high speed devices from both an EMI and an efficiency point of view is formulated together with an improved input filter design

Short-circuit fault analysis and isolation strategy for matrix converters

The behavior of matrix converter (MC) drive systems under the condition of MC short-circuit faults is comprehensively investigated. Two isolation strategies using semiconductors and high speed fuses (HSFs) for MC short-circuit faults are examined and their performances are compared. The behavior of MC drive systems during the fuse action time under different operating conditions is explored. The feasibility of fault-tolerant operation during the fuse action time is also studied. The basic selection laws for the HSFs and the requirements for the passive components of the MC drive system from the point view of short-circuit faults are also discussed. Simulation results are used to demonstrate the feasibility of the proposed isolation strategies

Cantor Spectrum for Schr\"odinger Operators with Potentials arising from Generalized Skew-shifts

We consider continuous $SL(2,\mathbb{R})$-cocycles over a strictly ergodic homeomorphism which fibers over an almost periodic dynamical system (generalized skew-shifts). We prove that any cocycle which is not uniformly hyperbolic can be approximated by one which is conjugate to an $SO(2,\mathbb{R})$-cocycle. Using this, we show that if a cocycle's homotopy class does not display a certain obstruction to uniform hyperbolicity, then it can be $C^0$-perturbed to become uniformly hyperbolic. For cocycles arising from Schr\"odinger operators, the obstruction vanishes and we conclude that uniform hyperbolicity is dense, which implies that for a generic continuous potential, the spectrum of the corresponding Schr\"odinger operator is a Cantor set.Comment: Final version. To appear in Duke Mathematical Journa

Is Eriophyes mali Nalepa present in Italy?

In the last few years, blistering symptoms were observed on apple plants in commercial orchards. Blisters are commonly found on apple leaves as well as on small fruits. This symptom is compatible with that described for apple blister mites belonging to the genus Eriophyes (Eriophyidae). To assess the identity of the etiological agent, leaf blisters and buds of symptomatic apple and, as a control, pear plants were examined under the dissection microscope and eriophyoid mites were collected. Specimens were examined using both molecular and morphological approaches. The analysis of sequences confirmed that eriophyoid mites collected from symptomatic apple and pear plants are genetically different. Our analyses highlight a complex scenario inside the genus Eriophyes that is worth to be studied in more detai

On the criticality of inferred models

Advanced inference techniques allow one to reconstruct the pattern of interaction from high dimensional data sets. We focus here on the statistical properties of inferred models and argue that inference procedures are likely to yield models which are close to a phase transition. On one side, we show that the reparameterization invariant metrics in the space of probability distributions of these models (the Fisher Information) is directly related to the model's susceptibility. As a result, distinguishable models tend to accumulate close to critical points, where the susceptibility diverges in infinite systems. On the other, this region is the one where the estimate of inferred parameters is most stable. In order to illustrate these points, we discuss inference of interacting point processes with application to financial data and show that sensible choices of observation time-scales naturally yield models which are close to criticality.Comment: 6 pages, 2 figures, version to appear in JSTA

إعداد مواد تعليمية لتنمية المهارات اللغوية لطلبة الصفّ الأول المتوسّط: بحث تطويريّ بمدرسة التوحيد المتوسّطة الدينية بنكالان مادورا.

Kegiatan Pembelajaran Bahasa Arab di Madrasah Diniah Tsanawiyah “At tauhid” Bangkalan Madura masih menggunakan buku ajar yang tidak sesuai, adapun kitab yang digunakan hanya memacu pada ketrampilan berbicara saja tidak pada 4 ketrampilan bahasa seperti mendengar, berbicara, membaca, menulis dan didalam kitab tersebut tidak terdapat latihan soal yang dapat memicu kemampuan bahasa arab para santri disana.maka dari itu penulis ingin mendesain bahan ajar yang bagus dan sesuai kurikulum 2013 kementrian agama RI karena kurikulum dapat membantu untuk mentertibkan proses belajar mengajar pada sekolah khususnya dalam pembuatan materi ajar bagi penulis. Penulis menggunakan metode Research and Developmentdengan pendekatan kuantitatif dan kualitatif untuk menganalisa data dan nilai, serta menjelaskan efektifitas penerapan Materi Ajar dalam pembelajaran bahasa arab adapun sampelnya adalah para santri kelas 1 tingkat Tsanawiyah yang berjumlah 15 santriwan/i. adapun teknik pengumpulan data penelitian ini yaitu: Observasi, interview, tes, dan dokumentasi. Dan hasil penelitian ini adalah: 1)Pengembangan bahan ajar yang terdesain memiliki beberapa proses tahap pembuatan agar memiliki karakter sebagai peningkatan kemampuan bahasa. 2)Adapun penerapannya dilihat dari proses pembuatan, langkah – langkah, dan ujicoba. 3)Adanya efektifitas dari materi ajar dibuktokan dengan adanya perubahan dari nilai pretest dan post test berdasarkan atas perbandingan t-hitung dan t-tabel yang menunjukkan t-hitung lebih besar dari pada t-tabel

Laminar-turbulent boundary in plane Couette flow

We apply the iterated edge state tracking algorithm to study the boundary between laminar and turbulent dynamics in plane Couette flow at Re=400. Perturbations that are not strong enough to become fully turbulent nor weak enough to relaminarize tend towards a hyperbolic coherent structure in state space, termed the edge state, which seems to be unique up to obvious continuous shift symmetries. The results reported here show that in cases where a fixed point has only one unstable direction, as for the lower branch solution in in plane Couette flow, the iterated edge tracking algorithm converges to this state. They also show that choice of initial state is not critical, and that essentially arbitrary initial conditions can be used to find the edge state.Comment: 4 pages, 4 figure