The Existence of Cartan Connections and Geometrizable Principal Bundles

The aim of this article is to proof a necessary and sufficient condition for the existence of a Cartan connection on a principal bundle. After collecting the essentially well known facts to fix the terminology, soldering forms and geometrizable principal bundles are defined to finally prove the existence criterion.Comment: 6 pages, corrected the principal typo :

On the Ext-computability of Serre quotient categories

To develop a constructive description of $\mathrm{Ext}$ in categories of coherent sheaves over certain schemes, we establish a binatural isomorphism between the $\mathrm{Ext}$-groups in Serre quotient categories $\mathcal{A}/\mathcal{C}$ and a direct limit of $\mathrm{Ext}$-groups in the ambient Abelian category $\mathcal{A}$. For $\mathrm{Ext}^1$ the isomorphism follows if the thick subcategory $\mathcal{C} \subset \mathcal{A}$ is localizing. For the higher extension groups we need further assumptions on $\mathcal{C}$. With these categories in mind we cannot assume $\mathcal{A}/\mathcal{C}$ to have enough projectives or injectives and therefore use Yoneda's description of $\mathrm{Ext}$.Comment: updated bibliography and deleted remaining occurrences of "maximally

On monads of exact reflective localizations of Abelian categories

In this paper we define Gabriel monads as the idempotent monads associated to exact reflective localizations in Abelian categories and characterize them by a simple set of properties. The coimage of a Gabriel monad is a Serre quotient category. The Gabriel monad induces an equivalence between its coimage and its image, the localizing subcategory of local objects.Comment: fixed Prop. 2.10, updated bibliograph

シアノ架橋配位高分子の熱処理によるナノ構造有する酸化物及び炭化物の合成

早大学位記番号:新7333早稲田大

Decomposing Total Factor Productivity Change of Cotton Cultivars (Barakat-90 and Barac (67)B) in the Gezira Scheme (1991 – 2007) Sudan

The main objective of this paper was to decompose Total Factor Productivity Change (TFPCH) of cotton cultivars Barakat-90 and Barac(67)B in the Gezira scheme in 1991-2007, based on Data Envelopment Analysis Program (DEAP) Software Version 2.1, using model of input–oriented Malmquist indices Total Factor Productivity (TFP). This model could give meaningful results regarding technological and economic behavior relationship over time using balance panel data on Barac(67)B and Barakat-90 cultivars, Relevant secondary data were collected and analyzed to meet the stated objectives. This paper was aimed to decompose TFPCH into two components Technological Change (TECH) and Technical Efficiency Change (EFCH) and the latter was further divided into Scale Efficiency Change (SEFCH) and Pure Efficiency Change (PEFCH). The methodology allowed the recovery of various efficiency and productivity measures. The paper was mainly to answer the questions related to technical efficiency, scale efficiency and productivity changes. In the study on cotton cultivars, the innovation was improving up and down of TECH over time. Scale inefficiency was the main problem in efficiency analysis and mainly due to production operating at increasing returns to scale in Barac(67)B and Barakat-90 operating at constant return to scale. TFPCH was -1.3%, the contribution of EFCH was -1.6% and TECH was 0.30%, the main problem was efficiency change and this was mainly due to scale inefficiency, Barac(67)B contributed to this negative at an average annual rate -3.3%. This implying that the Barac(67)B was ailing due to efficiency change. The study has recommended, substantial improvement in knowledge about productivity and efficiency using scientific approaches, the scheme administration should take full advantage of Barac(67)B cultivar to be extensively grown, Barakat-90 requires further investigation benefiting from technological innovation, additional, improvement in agricultural processing to increase the value added, and the benefit of scientific breakthrough in agricultural science are also recommended.Crop Production/Industries,

Conley: Computing connection matrices in Maple

In this work we announce the Maple package conley to compute connection and C-connection matrices. conley is based on our abstract homological algebra package homalg. We emphasize that the notion of braids is irrelevant for the definition and for the computation of such matrices. We introduce the notion of triangles that suffices to state the definition of (C)-connection matrices. The notion of octahedra, which is equivalent to that of braids is also introduced.Comment: conley is based on the package homalg: math.AC/0701146, corrected the false "counter example

Coxeter and crystallographic arrangements are inductively free

AbstractUsing the classification of finite Weyl groupoids we prove that crystallographic arrangements, a large subclass of the class of simplicial arrangements which was recently defined, are hereditarily inductively free. In particular, all crystallographic reflection arrangements are hereditarily inductively free, among them the arrangement of type E8. With little extra work we prove that also all Coxeter arrangements are inductively free

A Comparative Study of Time-Frequency Representations for Fault Detection in Wind Turbine

To reduce the cost of wind energy, minimization and prediction of maintenance operations in wind turbine is of key importance. In variable speed turbine generator, advanced signal processing tools are required to detect and diagnose the generator faults from the stator current. To detect a fault in non-stationary conditions, previous studies have investigated the use of time-frequency techniques such as the Spectrogram, the Wavelet transform, the Wigner-Ville representation and the Hilbert-Huang transform. In this paper, these techniques are presented and compared for broken-rotor bar detection in squirrel-cage generators. The comparison is based on several criteria such as the computational complexity, the readability of the representation and the easiness of interpretatio