Biogas energy technology in Sudan

Biogas from biomass appears to have potential as an alternative energy in Sudan, which is potentially rich in biomass resources. This is an overview of some salient points and perspectives of biogas technology in Sudan. The current literature is reviewed regarding the ecological, social, cultural and economic impacts of biogas technology. Sudan is blessed with abundant solar, wind, hydro, and biomass resources. Results suggest that biogas technology must be encouraged, promoted, invested, implemented, and demonstrated, but especially for remote rural areas.     

Characterization of the gene encoding the 16S rRNA of Enterobacter sakazakii and development of a species-specific PCR method

The gene encoding the 16S rRNA of Enterobacter (E.) sakazakii (ATCC 29544, plus four strains isolated from powdered infant formula) was studied, and the sequence compared with those of other Enterobacteriaceae in aspects of genetic variability. Sequence differences between E. sakazakii and other Enterobacteriaceae within the hypervariable regions V1, V2, and V3, respectively, were used to develop two PCR methods for E. sakazakii. PCR1 employed a primer pair located in V1/V2, while PCR2 utilized a primer pair located in V1/V3, respectively. The two PCR methods were tested against a set of 57 E. sakazakii and 148 non-E. sakazakii isolates. PCR1 gave an amplicon with a size of 406 bp and resulted in 100% positive results for E. sakazakii, but also detected Citrobacter koseri/amalonaticus and all nine tested Salmonella enterica serovars. In contrast, PCR2 (amplicon size of 952 bp) gave positive results only for E. sakazakii, thus allowing specific identification of this species.     

Diffusion coefficients and phase equilibria of carbon dioxide–ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) system

This article presents the mutual diffusion coefficients of a carbon dioxide–ionic liquid, [bmim][PF₆], system at temperatures of 313.15 and 323.15 K and pressures of 5 and 8 MPa. In order to estimate the diffusion coefficients, we have carried out experiments to find time-dependent carbon dioxide solubilities in the ionic liquid and then fit a transport model to the data. In a system containing high pressure carbon dioxide and ionic liquid, carbon dioxide dissolves in the liquid until its equilibrium mole fraction is reached. During this process, the position of the liquid–vapour interface and the density of the liquid phase change. To account for the variation in liquid density, an equation fit to the experimental density data is included in the transport model. To track the moving interface, the volume-of-fluid method is used. The diffusivities at dilute concentration and at thermodynamic phase equilibrium are determined and compared with the literature values and those obtained from correlations.     

Edge flux intensity functions in polyhedral domains and their extraction by a quasidual function method

The asymptotics of solutions to scalar second order elliptic boundary value problems in three-dimensional polyhedral domains in the vicinity of an edge is provided in an explicit form. It involves a family of eigen-functions with their shadows, and the associated edge flux intensity functions (EFIFs), which are functions along the edges. Utilizing the explicit structure of the solution in the vicinity of the edge we present a new method for the extraction of the EFIFs called quasidual function method. It can be interpreted as an extension of the dual function contour integral method in 2-D domains, and involves the computation of a surface integral J[R] along a cylindrical surface of radius R away from the edge as presented in a general framework in (Costabel et al., 2004). The surface integral J[R] utilizes special constructed extraction polynomials together with the dual eigen-functions for extracting EFIFs. This accurate and efficient method provides a polynomial approximation of the EFIF along the edge whose order is adaptively increased so to approximate the exact EFIF. It is implemented as a post-solution operation in conjunction with the p-version finite element method. Numerical realization of some of the anticipated properties of the J[R] are provided, and it is used for extracting EFIFs associated with different scalar elliptic equations in 3-D domains, including domains having edge and vertex singularities. The numerical examples demonstrate the efficiency, robustness and high accuracy of the proposed quasi-dual function method, hence its potential extension to elasticity problems.     

Synthesis of Scan Chains for Netlist Descriptions at RT-Level

This paper presents a methodology to insert scan paths in a functional Register Transfer Level (RTL) specification of a design that can exploit existing functional paths between sequential elements in the original circuit for establishing scan chains. The primary objective for RTL scan insertion is to reduce the time taken for DFT, and thus reduce the time to market. Additionally, building scan chains at the functional RT-Level is expected to reduce the total area overhead introduced by full scan without compromising the fault coverage achieved. In addition, it often eliminates the delay associated with the additional multiplexer as a part of a conventional scan-cell in high performance designs. Experimental results presented in this paper demonstrate that the proposed method achieves the above objectives while also achieving higher fault coverages for most of the benchmark circuits considered.