THE “EVAPORATIVE CAPACITY” AS A PERFORMANCE INDEX FOR A SOLAR-DRIER AIR-HEATER

This paper presents a new index, called the “evaporative capacity”, for rating the performance of the solar air heater in a solar drier consisting of solar air heater and a drying chamber in series. The proposed index complements the widely-used “collector efficiency” as a performance indicator of the solar collector, by taking into account the specific use that is to be made with the heated air. Presented is a detailed method for calculating the evaporative capacity, and a comparison of this new index with the thermal efficiency index, demonstrating its superiority. General charts for a rapid determination of the evaporative capacity are presented, and some possible applications of these charts are described.     

Hybrid offset‐time and burst assembly algorithm (H‐OTBA) for delay sensitive applications over optical burst switching networks

Optical burst switching (OBS) is the most favourable switching paradigm for future all‐optical networks. Burst assembly is the first process in OBS and it consists of aggregating clients packets into bursts. Assembled bursts wait for an offset time before being transmitted to their intended destinations. Offset time is used to allow burst control packet reserve required resources prior to burst arrival. Burst assembly process and offset‐time create extra delay in OBS networks. To make OBS suitable for real time applications, this extra latency needs to be controlled. This paper proposes and evaluates a novel offset time and burst assembly scheme to address this issue. Constant bit rate (CBR) traffic that has stringent end‐to‐end delay QoS requirements is used in this study. The proposed scheme is called hybrid offset‐time and burst assembly algorithm (H‐OTBA). The objective of the paper is achieved by controlling maximum burst transfer delay parameters of CBR. The proposed scheme was evaluated via network simulation. Simulation results demonstrate that, H‐OTBA has effectively reduced end‐to‐end delay for CBR traffic compared with current solutions. Copyright © 2014 John Wiley & Sons, Ltd.     

Eco Insulation Materials： Reduction of Cooling Loads of a House Made of Breeze Block or Laterite in a Dry Tropical Climate

In this paper, we study the influence ofeco materials for roof insulation and fiber-reinforced mortar coatings on cooling loads of a home in dry tropical climate. The walls of the house are made of cinderblock or laterite and the insulating material of a roof panel is made with lime （24%）, cement （6%）, water （50%） of vegetable fibers hibiscus sabdariffa （16%）, tree widespread in Burkina Faso and sugar cane bagasse （4%）. This panel roof insulation and the fiber-reinforced mortar were characterized at the Laboratory of Physics and Chemistry of the environment by the hot plate method. The building is modeled in TRNSYS using climate data from the city of Ouagadougou. The results obtained show that in the warmer months of the year, that is to say in March and April, the relative differences between heat gains the configurations ＂breeze block-coating mortar and roof not insulated＂ and ＂laterite- fiber-reinforced mortar coating and insulated roof＇ vary between 15.6% and 16.8%. The configuration ＂laterite-fiber-reinforced mortar coating and insulated roof allows a reduction of annual heat gains of 15.5% compared to the configuration ＂breeze block-coating mortar and roof not insulated＂.     

Assessment of the bacteriological quality and nitrate pollution risk of Quaternary groundwater in the southern part of Abidjan District (Côte d’Ivoire)

In this study, total coliforms, thermotolerant coliforms, Escherichia coli and groundwater nitrate concentration were monitored at 127 groundwater sampling points (only 62 water points for bacteriological parameters) located in the southern part of Abidjan District. Each water sampling location was sampled in March and July 2007, representing respectively the long dry season and the long wet season. Geostatistical methods were used to analyze the spatial variability of nitrates and the groundwater nitrate pollution risk. The maximum seasonal content of total coliforms and thermotolerant coliforms ranged from 400 to 1000 CFU/100 mL and from 200 to 500 CFU/100 mL respectively. Moreover, 94% of these locations presented traces of bacteriological contamination. This contamination was mainly recorded during the rainy period. The degree of correlation between bacterial abundance and chemical parameters is variable. Nitrites, ammonium and potassium favoured coliform abundance. In the 127 water points, groundwater nitrate concentrations ranged from 4 to 198 mg L^?1 and were log-normally distributed in the study area. The groundwater contamination risk map indicated that the strongly urbanized west side of the site presented a high probability of exceeding the WHO drinking water standard (50 mg L^?1NO₃^?).     

UHF Propagation Parameters to Support Wireless Sensor Networks for Onboard Trains

This paper reports numerical results for the characterization of the propagation channel in a train. Since the availability of a train to carry out measurements is not always easy, particularly when many changes must be done, a simulation tool provides a useful and reliable mean for the evaluation of the propagation characteristics of this complex and highly fluctuating channel. In order to benefit from previous results, the various existing softwares for complex electromagnetic fields environments simulations were fully searched and one that seems best suited has been retained for these computations. The results presented here are original, preliminaries and our approach provides a basis for study the propagation of waves in a very complex environment consisting of different electromagnetic fields like a train.     

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.     

Skin diseases disclosing human immunodeficiency virus infection in Mali

BACKGROUND: Ultrafiltration failure (UFF) is a complication of peritoneal dialysis (PD) treatment that occurs especially in long-term patients. Etiological factors include a large effective peritoneal surface area [measured as high mass transfer area coefficient (MTAC) of creatinine], a high effective lymphatic absorption rate (ELAR), a large residual volume, or combinations. OBJECTIVE: The prevalence and etiology of UFF were studied and the contribution of transcellular water transport (TCWT) was analyzed. A new definition of UFF and guidelines for the analysis of its etiology were derived from the results. SETTING: Peritoneal dialysis unit in the Academic Medical Center in Amsterdam. DESIGN: Cross-sectional study of standard peritoneal permeability analyses (4-hr dwells, dextran 70 as volume marker) with 1.36% glucose in 68 PD patients. Patients with negative net UF (change in intraperitoneal volume, dIPV < 0 mL) were analyzed further using 3.86% glucose, whenever possible. RESULTS: Among 68 patients (duration of PD 0.3-178 months), 39 had negative net UF with 1.36% glucose. These patients had greater MTAC creatinine and glucose absorption, and higher ELAR (p < 10(-4)) than the patients with positive UF. dIPV and transcapillary UF rate (TCUFR) were lower (p < 10(-5)). Twenty of these patients could be studied using 3.86% glucose. dIPV was greater than 400 mL/4 hr in this test in 12 patients, implying that no clinically important UFF was present. Ultrafiltration failure (dIPV < 400 mL) was found in 8 patients, giving a prevalence of 23%. This last group had been treated with PD for a longer period (p = 0.03), had higher ELAR (p = 0.07), but lower residual volume (p = 0.03), and lower TCUFR (p = 0.01). Ultrafiltration failure was associated with a high MTAC creatinine in 3 patients, a high ELAR in 4 patients, and a combination of factors in one. As an additional possible cause, TCWT was studied, using the sodium gradient in the first hour of the dwell, corrected for diffusion (dNA). Five patients had dNA > 5 mmol/L, indicating normal TCWT. The 3 patients with dNA < 5 mmol/L tended to be treated longer (p = 0.19) and had lower TCUFR (p = 0.04). A smaller difference was found between dIPV 3.86% and 1.36% (p = 0.04) compared to the dNA > 5 mmol/L group, but no differences were present for MTAC creatinine, ELAR, residual volume, or glucose absorption. CONCLUSIONS: In addition to known factors, impairment of TCWT can be a cause of UFF. A standardized dwell with 1.36% glucose overestimates UFF. Therefore, 3.86% glucose should be used for identification of patients with UFF, especially because it provides additional information on TCWT. Ultrafiltration failure can be defined as net UF < 400 mL/4 hr with 3.86% glucose during a 4-hour exchange.     

Experimental characterisation and modelling of thin layer direct solar drying of Amelie and Brooks mangoes

Direct solar drying characteristics of Amelie and Brooks mangoes were experimentally determined using a solar dryer made up of four trays and used under weather conditions of fruit harvest period. Direct solar drying curves were established, fitted using 10 mathematical models and simulated with a direct solar drying model. Effective diffusivity, drying rates and drying efficiency were estimated for each drying day and each variety. Results showed that at least four days were necessary to reach the range of preservation water contents. Drying curves depended on variety and were suitably fitted by “two-term” and “Approximation of diffusion” models (with R² ≥ 0.9888, RMSE ≤ 0.0283, E ≤ 9.1283% and χ² ≤ 1.3314 × 10⁻⁴). Drying rates and drying efficiency significantly decreased with the number of drying days (respectively between 0 and 0.15 g kg⁻¹ s⁻¹ and between 0 and 34%) and were very close for the two varieties. Diffusivity weakly varied with variety and strongly decreased with the number of drying days between 2.7906 × 10⁻¹¹ and 1.8489 × 10⁻¹⁰ m²/s. Drying kinetics were suitably simulated by the direct solar drying model (with: Amelie: R² = 0.989 and E = 7.623%, Brooks: R² = 0.9924 and E = 4.961%). The final water content was about 24.83% for Amelie and 66.32% for Brooks and Amelie was the most suitable variety for direct solar drying.     

Evolution of weak ferroelectricity dielectric response in PbZrO3 antiferroelectric thin films

Journal of Materials Science: Materials in Electronics - In this study, the ferroelectric domain wall contributions to the permittivity is investigated in a PbZrO3 antiferroelectric thin film far...     

室内宽带多输入多输出抽头时延线新模型研究

根据室内无线电波传播规律和实测数据,研究建立了一个新的抽头时延线模型,该模型可以简单有效地估计视距和非视距路径下室内平均功率时延谱,并与实验结果一致.在广义平稳非相关散射信道前提下,通过分析抽头时延模型频率相关系数、抽头系数分布和相关性、抽头多普勒频谱等特性参数,给出了评估抽头时延线模型的新方法.文中建立的信道模型和参数,对于室内多输入多输出无线信道模拟仿真有较为重要的意义.