Analytical quantification of the impact of sub-slab gravel layer on the airflow from soil into building substructures

The entry of soil gas pollutants into buildings has been the subject of many studies and some analytical airflow models have been developed to estimate this entry into buildings. The existing airflow models do not include the sub-slab gravel layer that can influence significantly the airflow from soil into buildings. In this paper, an analytical airflow model, which considers this sub-slab gravel layer has been developed. Moreover, a 2D finite-element model has been used for numerical comparison. This comparison gave a satisfactory agreement with the analytical model. The airflow model is presented as flow-pressure equation and can be integrated easily in vapour intrusion models or ventilation models to enable the quantification of the impact of these pollutants on indoor air quality.     

A fault-tolerant control architecture for induction motor drives in automotive applications

This paper describes a fault-tolerant control system for a high-performance induction motor drive that propels an electrical vehicle (EV) or hybrid electric vehicle (HEV). In the proposed control scheme, the developed system takes into account the controller transition smoothness in the event of sensor failure. Moreover, due to the EV or HEV requirements for sensorless operations, a practical sensorless control scheme is developed and used within the proposed fault-tolerant control system. This requires the presence of an adaptive flux observer. The speed estimator is based on the approximation of the magnetic characteristic slope of the induction motor to the mutual inductance value. Simulation results, in terms of speed and torque responses, show the effectiveness of the proposed approach.     

Modeling and Experimental Study of 3-Phase Short-Circuits of a Double-Cage Induction Machine

Three-phase short-circuits of the induction machine yields to high levels of stress in an induction traction drive. To study these operations, the authors propose to model the machine by a multiple cage equivalent circuit. This enables us to take into account the deep bar effect with accuracy. The identification of the equivalent circuit and its validation are carried out experimentally for a 30-kW double-cage induction motor.     

Dynamic model of a hermetic reciprocating compressor in on–off cycling operation (Abbreviation: Compressor dynamic model)

This paper presents a dynamic model of a hermetic reciprocating compressor in on–off cycling operation. The proposed model is detailed enough to account for the important phenomena influencing the suction and discharge mass flow rates and the electrical power drawn by the compressor, but simple enough to be usable for different reciprocating compressor designs with readily available data from manufacturers. The experimental validation of the model under steady-state and transient conditions in both heating and cooling modes confirms the good performance of the model.     

Critical success factors for World Bank projects: An empirical investigation

This paper analyzes the results of a survey that aims to explore World Bank project success factors and specifically the relationship between critical success factors (CSFs) and project success as perceived by World Bank Task Team Leaders (project supervisors). The exploratory factor analysis highlights a specific set of five CSFs: monitoring, coordination, design, training, and institutional environment. The regression analysis shows that there is a statistically significant and positive relationship between each of the five CSFs and project success. Consistent with theory and practice, the most prominent CSFs for project supervisors are design and monitoring. The findings contribute to the project CSF literature by conceptualizing project supervision as a multidimensional construct and by confirming supervision as a generic CSF for World Bank projects. The World Bank project supervisors and managers should strengthen project design and monitoring and thus improve project implementation as well as the chances for project success.     

Branched polymeric media: boron-chelating resins from hyperbranched polyethylenimine

Extraction of boron from aqueous solutions using selective resins is important in a variety of applications including desalination, ultrapure water production, and nuclear power generation. Today's commercial boron-selective resins are exclusively prepared by functionalization of styrene-divinylbenzene (STY-DVB) beads with N-methylglucamine to produce resins with boron-chelating groups. However, such boron-selective resins have a limited binding capacity with a maximum free base content of 0.7 eq/L, which corresponds to a sorption capacity of 1.16 ± 0.03 mMol/g in aqueous solutions with equilibrium boron concentration of ～70 mM. In this article, we describe the synthesis and characterization of a new resin that can selectively extract boron from aqueous solutions. We show that branched polyethylenimine (PEI) beads obtained from an inverse suspension process can be reacted with glucono-1,5-d-lactone to afford a resin consisting of spherical beads with high density of boron-chelating groups. This resin has a sorption capacity of 1.93 ± 0.04 mMol/g in aqueous solution with equilibrium boron concentration of ～70 mM, which is 66% percent larger than that of standard commercial STY-DVB resins. Our new boron-selective resin also shows excellent regeneration efficiency using a standard acid wash with a 1.0 M HCl solution followed by neutralization with a 0.1 M NaOH solution.     

Model-based data engineering for Web services

Although XML offers heterogeneous IT systems a new level of interoperability, it doesn't ensure that the various systems correctly interpret the data they receive. To address this, data engineering supports clear definitions for exchanged data elements. With model-based data engineering, organizations use a common reference model, which offers further clarity and performance improvements. Organizations can use the resulting data to configure mediation services, translating dialects of new or legacy services into a common language for use in a service-oriented architecture.     

Improved detection of HIV-2 proviral DNA in dually seroreactive individuals by PCR

OBJECTIVE: To improve the detection rate of HIV-2 proviral DNA in primary uncultured peripheral blood mononuclear cells (PBMC) of HIV-2-seroreactive and HIV-1-HIV-2 dually seroreactive individuals. MATERIALS AND METHODS: Two newly designed HIV-2 PCR primer pairs in the long terminal repeat (LTR) gag and gag-pol regions and a previously described env and LTR HIV-2 PCR primer pairs were tested on samples from 66 confirmed HIV-2-seropositive individuals (The Gambia, 40; C?te d'Ivoire, 17; Guinea-Bissau, nine), 209 dually seroreactive individuals (The Gambia, 82; C?te d'Ivoire, 127), 24 genetically characterized isolated HIV-1 strains (group M subtypes A-H and group O), one simian immunodeficiency virus (SIV) strain cpz, 10 HIV-2 isolates (subtype A, B and unidentified), two SIVsm isolates, and 10 seronegative samples. RESULTS: All HIV-2 primers evaluated showed 100% specificity since there was no amplification observed with 24 HIV-1, one SIVcpz and 10 seronegative samples. One single copy of the HIV-2 genome could be detected with all outer primer pairs as well as all inner primer pairs on one PCR round used. Sensitivity of primers (at least one of the four primer pairs was positive) to HIV-2-seropositive samples was 100% (all nine) in Guinea-Bissau, 71% (12/17) in C?te d'Ivoire, 100% (all 20) in Gambian AIDS patients, and 85% (17/20) in Gambian pregnant women. Doubling the PBMC of dually seroreactive individuals from 7.5 x 10(4) to 1.5 x 10(5) in the PCR revealed the presence of both HIV-1 and 2 proviral DNA in 72% (92/127) in C?te d'Ivoire and 72% (59/82) in The Gambia. By doubling the number of PBMC, HIV-2 detection in dually seroreactive individuals by PCR was increased from 65 to 77% in C?te d'Ivoire and from 67 to 83% in The Gambia. CONCLUSIONS: The use of 1.5 x 10(5) primary uncultured PBMC and the newly designed HIV-2 primer pairs allowed us to document the highest percentage (72%) ever reported of HIV-1-HIV-2 dual infections amongst HIV-1-HIV-2 dually seroreactive individuals in C?te d'Ivoire and The Gambia. Improved detection of HIV-2 proviral DNA, rather than exposure to both viruses, infection with only one virus, or infection with a unique third virus containing epitopes common to both HIV-1 and HIV-2, contributes to a more accurate monitoring of the prevalence of HIV-1-HIV-2 dual infections.     

Impact of antimalarial drug accessibility on malarial morbidity and chloroquine resistance. A study carried out in Touba (Senegal)

In Touba, more important accessibility to antimalarial drugs and their uncontrolled use let to assure that the rate of malarial morbidity would be lower there than in other place in Senegal whereas the rate of chloroquine resistance would be higher. A checking survey of these assumptions has been carried out from october 15 to november 10, 1995 in Touba's health center. Among 227 feverish subjects investigated, 111 were Plasmodium falciparum carriers. Malarial bouts accounted for 48.9% of the feverish fits observed and for the major cause of consultation during the rainy season. These figures are higher than those usually observed in urban environment. Conversely, the rate of chloroquine resistance is lower than those observed in urban zones, since the therapeutic efficacy of chloroquine on Plasmodium falciparum was 100% in that survey.