Representations and KK-theory of Discrete Groups

Let $\Gamma$ be a discrete group of finite virtual cohomological dimension with certain finiteness conditions of the type satisfied by arithmetic groups. We define a representation ring for $\Gamma$, determined on its elements of finite order, which is of finite type. Then we determine the contribution of this ring to the topological $K$-theory $K^*(B\Gamma)$, obtaining an exact formula for the difference in terms of the cohomology of the centralizers of elements of finite order in $\Gamma$.Comment: 4 page

The Condominium Scheme as a Strategy for Housing Slum Dwellers: the case of Gofa Mebrat Hail Condominium, Addis Ababa, Ethiopia

Ethiopia, like other developing nations, is striving to improve the life of its urban dwellers and Addis Ababa, the capital city, is receiving special attention to bring it up to standards in the continent. At 125 years old, the city suffers from severe housing shortage and is characterized by poor housing, infrastructural and neighborhood conditions. Considering the housing agenda as uppermost of the urban development challenge the city administration initiated a program to build several thousand homes based on the condominium concept for different categories of income groups. The initial target of the program, though, was the low income and lower middle income groups. Eleven years have passed since the program commenced in 2004. Needless to mention, even though home ownership has grown phenomenally, the price of a unit of condominium house has risen dangerously over the period. This article is based on ongoing doctoral study and looks at the affordability challenges of the condominium housing scheme, particularly regarding the poor slum dwellers and considers possible alternative means to tackle the issue. The specific study site is the Gofa-Mebrat Hail Condominium in Nefas Silk-Lafto Sub-city of Addis Ababa. The article gives a background account of the procedures followed by the researcher in the study: descriptive and analytical research methods employed, numerical and non-numerical data collected, questionnaires deployed for the household survey, interviews conducted, and relevant observations made. Moreover, secondary sources of information were available to aid analysis and corroborate findings. The most critical finding of the study was that the affordability challenge was, barring free offers or heavy subsidization, beyond prudent financial amelioration and that the only way to keep the poor slum dwellers housed was for them to pay a monthly housing mortgage installment dictated, largely, by a formula based on their ability-to-pay. Key Words: Condominium Scheme, Housing, Slum Dwellers, home finance

Evolved model for early fault detection and health tracking in marine diesel engine by means of machine learning techniques

The Coast Guard Command, which has a wide range of duties as saving human lives, protecting natural resources, preventing marine pollution and battle against smuggling, uses diesel main engines in its ships, as in other military and commercial ships. It is critical that the main engines operate smoothly at all times so that they can respond quickly while performing their duties, thus enabling fast and early detection of faults and preventing failures that are costly or take longer to repair. The aim of this study is to create and to develop a model based on current data, to select machine learning algorithms and ensemble methods, to develop and explain the most appropriate model for fast and accurate detection of malfunctions that may occur in 4-stroke high-speed diesel engines. Thus, it is aimed to be an exemplary study for a data-based decision support mechanism

Magnetodielectric and magnetoelastic coupling in TbFe3(BO3)4

We have studied the magnetodielectric and magnetoelastic coupling in TbFe3(BO3)4 single crystals by means of capacitance, magnetostriction and Raman spectroscopy measurements. The data reveal strong magnetic field effects on the dielectric constant and on the macroscopic sample length which are associated to long range magnetic ordering and a field-driven metamagnetic transition. We discuss the coupling of the dielectric, structural, and magnetic order parameters and attribute the origin of the magnetodielectric coupling to phonon mode shifts according to the Lyddane-Sachs-Teller (LST) relation.Comment: Accepted for publication in Physical Review

A Procedure to Construct Exact Solutions of Nonlinear Fractional Differential Equations

We use the fractional transformation to convert the nonlinear partial fractional differential equations with the nonlinear ordinary differential equations. The Exp-function method is extended to solve fractional partial differential equations in the sense of the modified Riemann-Liouville derivative. We apply the Exp-function method to the time fractional Sharma-Tasso-Olver equation, the space fractional Burgers equation, and the time fractional fmKdV equation. As a result, we obtain some new exact solutions

Parametric Study of a Turbojet Engine With Auxiliary Bypass Combustion- The TurboAux Engine

A parametric study of a novel turbojet engine with an auxiliary combustion chamber, nicknamed the TurboAux engine is presented. The TurboAux engine is conceived as an extension of a turbojet engine with an auxiliary bypass annular combustion chamber around the core stream. The study presented in this article is motivated by the need to facilitate clean secondary burning of fuel at temperatures higher than conventionally realized from air exiting the low-pressure compressor. The parametric study is initiated by performing a simple optimization analysis to identify optimal ‘fan’ pressure ratios for a series of conventional low-bypass turbofan engines with varying bypass ratios (0.1 to 1.5). The fan pressure ratios for corresponding bypass ratios are chosen for studying varying configurations of the TurboAux engine. The article is presented in two phases – (i) Phase I presents the simulations carried out to arrive at an optimal configuration of a TurboAux engine and it formulation, (ii) Phase II presents simulations and results to compare the performance of a low-bypass turbofan engine to the TurboAux engine. The formulation and results are an attempt to make a case for charter aircrafts and efficient close-air-support aircrafts

Syzygies in equivariant cohomology for non-abelian Lie groups

We extend the work of Allday-Franz-Puppe on syzygies in equivariant cohomology from tori to arbitrary compact connected Lie groups G. In particular, we show that for a compact orientable G-manifold X the analogue of the Chang-Skjelbred sequence is exact if and only if the equivariant cohomology of X is reflexive, if and only if the equivariant Poincare pairing for X is perfect. Along the way we establish that the equivariant cohomology modules arising from the orbit filtration of X are Cohen-Macaulay. We allow singular spaces and introduce a Cartan model for their equivariant cohomology. We also develop a criterion for the finiteness of the number of infinitesimal orbit types of a G-manifold.Comment: 28 pages; minor change

Magnetodielectric coupling of a polar organic-inorganic hybrid Cr(II) phosphonate

Cr[(H(3)N-(CH(2))(2)-PO(3))(Cl)(H(2)O)] represents a rare example of a polar organic-inorganic hybrid material that exhibits a canted antiferromagnetic order below T(N)=5.5 K. The unusual coexistence of a polar crystal structure and magnetic order triggered our investigation of the magnetodielectric coupling. The coupling is evidenced by an anomaly in the temperature dependence of the dielectric constant epsilon below the Neel temperature. The magnetocapacitance is enhanced by one order of magnitude below T(N). The main characteristics of the magnetodielectic response are interpreted by Landau theoretical coupling terms