Energy-saving light positioning using heuristic search

A new definition is given to the problem of light positioning in a closed environment, aiming at obtaining, for a global illumination radiosity solution, the position and emission power for a given number of lights that provide a desired illumination at a minimum total emission power. Such a desired illumination is expressed using minimum and/or maximum values of irradiance allowed, resulting in a combinatory optimization problem. A pre-process computes and stores irradiances for a pre-established set of light positions by means of a radiosity random walk. The reuse of photon paths makes this pre-process reasonably cheap. Different heuristic search algorithms, combined to linear programming, are discussed and compared, from the simplest hill climbing strategies to the more sophisticated population-based and hybrid approaches. The paper shows how the presented approaches make it possible to obtain a good solution to the problem at a reasonable cost.     

Study of the useful yield of the Storing Matter technique using Ge(1 0 0) as a sputter target

Storing Matter is a new analytical technique for organic and inorganic materials, which tries to circumvent the well-known matrix effect in SIMS. This technique consists of separating the sputtering of the sample from the subsequent analysis steps. Thus, the sample to be analysed is sputtered with a focused ion beam produced by a floating low-energy ion gun (FLIG) and the particles emitted under the ion impacts are deposited at a sub-monolayer level on a well-known collector. The collector with the deposited material is then analysed in a second step by SIMS (dynamic and static mode). The main advantage of this new technique is to improve the sensitivity and the quantification of the SIMS analysis. All the processes, including all the sample and collector transfers, are performed in UHV conditions. This paper presents preliminary results obtained on the Storing Matter prototype instrument developed in our laboratory. The sputtering of a (1 0 0) Ge wafer by ions was used as a model system to study the influence of using different collector surfaces (W, Ta and Al) on the Storing Matter useful yield.     

Chromium (III) uptake by agro-waste biosorbents: Chemical characterization, sorption–desorption studies, and mechanism

Within their complex structure, agro-waste materials such as sorghum straw (SS), oats straw (OS) and agave bagasse (AB) have functional groups (i.e. carboxyl and phenolic) that play a major role in metals sorption. The advantages of these materials include availability, low-cost, and a reasonable metal sorption capacity. These agro-waste materials were chemically characterized by acid-base titrations and ATR-FTIR analyses in order to determine their functional groups, equilibrium constants, and surface charge distribution. Batch experiments were conducted at pH 3 and 4, at 25 °C and 35 °C to determine the biosorbents chromium (III) sorption capacity. Partially saturated biosorbents were desorbed with HNO₃, NaOH, and EDTA at different concentrations and temperatures (25 °C, 35 °C, and 55 °C). Finally, the chromium (III) sorption mechanism was discussed.Agro-waste materials functional groups are associated, in part, to carboxyl and hydroxyl groups: these oxygen-containing sites play an important role in the chromium (III) removal. The maximum chromium (III) sorption capacity was 6.96, 12.97, and 11.44 mg/g at pH 4 for acid-washed SS, OS, and AB, respectively. The chromium (III) sorption capacity decreased at pH 3 because H⁺ ions competed for the same functional groups. On the other hand, an increase in temperature enhanced both the biosorbents chromium (III) sorption capacity and their desorption by EDTA. The most probable chromium (III) sorption mechanisms were ion exchange and complexation.The agro-waste materials studied herein efficiently remove chromium (III) from aqueous solution and, most importantly, EDTA can efficiently desorb Cr (III) from agro-waste materials at 55 °C.     

Unequal spatial distribution of retrofits in Bucharest’s apartment buildings

This paper argues that the current spatial patterns of energy retrofits in post-socialist apartment buildings are unequally distributed across municipalities in Bucharest, Romania. In addition to the dominant techno-economic and social framing of this type of retrofit action, an institutional and political perspective can provide useful insights into why this occurs. By drawing on secondary analysis of statistical data, grey literature and 20 semi-structured interviews in Bucharest, three important findings emerge. First, the institutional complexity of energy retrofit of apartment buildings in Romania is underestimated and the interaction between various institutions is poor, explained by lack of trust and collective action. Second, the spatial distribution of the retrofit of apartment buildings is unequally distributed across Bucharest’s six municipalities. Third, current action for retrofit does not reach municipalities with the greatest need and potential. A more bottom-up and decentralized institutional landscape exists than is currently acknowledged in public policy and the research literature. Findings show an unequal and unfair spread of retrofit action within and between cities – raising wider implications for the potential shortcomings of European Union retrofit programmes in Central and Eastern Europe.     

An analysis of the relationship between morbidity and the level of demand for pediatric primary care. A study on 1359 children]

An entomological study was carried out in Ndiop village, Senegal, an area of sudan-type savana, from January to December 1995, to compare the malaria inoculation rate measured by the dissection of salivary glands of anophelines and the enzyme-linked immunosorbent assay (ELISA). Mosquitoes were sampled by night-bite collections. Species from the Anopheles gambiae complex were identified using the polymerase chain reaction. 1292 females Culicidae were collected. 597 anophelines mosquitoes known to be malaria vectors were captured during 148 man-nights of capture. Of the 572 anophelines investigated, 14 were positive using dissection while 21 were found to be positive with ELISA. The sporozoite rates were 2.5%, 2.2% and 3.8% for An. arabiensis, An. gambiae and An. funestus, respectively. The circumsporozoite rates were 3.5%, 2.2% and 7.7% for these three species, respectively. ELISA detected 1.5 times more positive mosquitoes than dissection. These results are discussed with reference to the duration of the sporogonic cycle, the delay before CSP antigens are apparent, and the daily survival rate of Anopheles mosquitoes.     

Evaluation of thermal comfort using combined CFD and experimentation study in a test room equipped with a cooling ceiling

This paper reports a full-scale experimental campaign and a computational fluid dynamics (CFD) study of a radiant cooling ceiling installed in a test room, under controlled conditions. This research aims to use the results obtained from the two studies to analyze the indoor thermal comfort using the predicted mean vote (PMV). During the whole experimental tests the indoor humidity was kept at a level where the condensation risk was minimized and no condensation was detected on the chilled surface of the ceiling. Detailed experimental measurements on the air temperature distribution, surface temperature and globe temperature were realized for different cases where the cooling ceiling temperature varied from 16.9 to 18.9 °C. The boundary conditions necessary for the CFD study were obtained from the experimental data measurements. The results of the simulations were first validated with the data from the experiments and then the air velocity fields were investigated. It was found that in the ankle/feet zone the air velocity could pass 0.2 m/s but for the rest of the zones it took values less than 0.1 m/s. The obtained experimental results for different chilled ceiling temperatures showed that with a cooling ceiling the vertical temperature gradient is less than 1 °C/m, which corresponds to the standard recommendations. A comparison between globe temperature and the indoor air temperature showed a maximum difference of 0.8 °C being noticed. This paper also presents the radiosity method that was used to calculate the mean radiant temperature for different positions along different axes. The method was based on the calculation of the view factors and on the surface temperatures obtained from the experiments. PMV plots showed that the thermal comfort is achieved and is uniformly distributed within the test room.