scholarly journals Experimental Study of the Effect of Curing Mode on Concreting in Hot Weather

2021 ◽  
Vol 31 (4) ◽  
pp. 243-248
Author(s):  
Nassima Bakir
Keyword(s):  
Experimental Study ◽  
Concrete Surface ◽  
Work Conditions ◽  
Climatic Conditions ◽  
Water Evaporation ◽  
Negative Effects ◽  
Climate Conditions ◽  
Hot Climate ◽  
Hot Weather ◽  
Job Site

Most developing countries have hot climate, ordinary jobsites characterized by reduced of human resources, equipment and infrastructures. The objective of this article is to make an experimental study of the influence of the hot climate such as that of Algeria, on the different properties of concrete in the fresh state, such as excessive water evaporation from the concrete surface, increased demand for water, increased slump loss corresponding to additional water on job-site, higher plastic shrinkage cracking and difficulty in controlling air content. At the hardened state, we could mention a reduction of strength at 28 days, decreased durability resulting from cracking at long-term period. To show the problems linked to concreting under these conditions and to present the appropriate solutions concrete or mortar can withstand the conditions in which it is implemented. Thus, negative effects caused principally by hot weather concreting motivated the choice of the such study. The research experimental work conditions in which the cementitious matrix was kept concerned two different environments, namely hot and dry climate conditions (t = 40°, h = 0%) alike the climate of the region of M'sila., and that of a medium with a hot and humid environment (t = 40°, h = 100%). The output of the investigation demonstrated the crucial role of the cure method in hot regions. The comparison of results for a reference concrete kept in air without any curing measures with two curing types simulating hot weather environment of the region M’sila was undertaken. These obtained outcome results were discussed based on the influence of climatic conditions to conclude procedures for hot weather concreting and suitable cure methods.

scholarly journals Opaque Ventilated Façade (OVF) Thermal Performance Simulation for Office Buildings in Brazil

2020 ◽  
Vol 12 (18) ◽  
pp. 7635
Author(s):  
Camila Gregório-Atem ◽  
Carolina Aparicio-Fernández ◽  
Helena Coch ◽  
José-Luis Vivancos
Keyword(s):  
Mineral Wool ◽  
Climatic Conditions ◽  
Office Buildings ◽  
Aluminium Composite ◽  
Specific Design ◽  
Performance Simulation ◽  
Climate Conditions ◽  
Hot Climate ◽  
Occupant Comfort ◽  
Ventilated Facade

Opaque ventilated façades (OVFs) are increasingly gaining in importance in the design of sustainable buildings, given that they can lessen the building´s environmental impact. Opaque ventilated façades can reduce thermal gains in hot climate zones, improving the thermal comfort indoors, and reducing air conditioning demand. Nevertheless, the thermal behaviour of the opaque ventilated façade depends on the climatic conditions and the building´s specific design. This study analyses the effect of opaque ventilated façades in office buildings using 30 constructive configurations under eight tropical climate conditions. The study considers three options for the external layer of cladding (ceramic, stone, and aluminium composite material) and two configurations for the inner layer (plasterboard with mineral wool and ceramic). Simulations were carried out using the software tools TRanNsient SYstem Simulation program (TRNSYS) and TRNFlow. The model developed considers bioclimatic characteristics, including solar radiation and wind conditions for each climatic zone. The operating temperature was selected from within the range established by occupant comfort regulations. The findings suggest that it is possible to select the best office building opaque ventilated façade configuration for each of the specific climate conditions in Brazil.

Strength of Modified Concretes Curing without Care in Dry and Hot Climate Conditions

2017 ◽  
Vol 753 ◽  
pp. 337-342
Author(s):  
Dmitry D. Koroteev ◽  
Makhmud Kharun ◽  
Vera V. Galishnikova ◽  
Nadezhda A. Stashevskaya
Keyword(s):  
Environmental Conditions ◽  
Negative Impact ◽  
Concrete Strength ◽  
Research Work ◽  
Water Evaporation ◽  
Chemical Additives ◽  
Minimum Period ◽  
Design Strength ◽  
Climate Conditions ◽  
Hot Climate

The speed of concrete curing and design concrete strength depend on the environmental conditions of construction site. Dry and hot climate conditions intensify the process of water evaporation from concrete and cause the concrete shrinkage and the loss of the potential concrete strength. The research work is devoted to study the layer changes of the concrete strength; determination of the minimum period of care for concrete; assessment of negative impact of dry and hot climate conditions on modified concretes, prepared on the composite binders with various chemical additives. The results and methodology, as well as the information about concrete composition and the boundary conditions of the experiments are given in the research work. The obtained research results show that chemical additives and composite binders with low water consumption contribute to get the design strength in spite of the environmental conditions. They also allow concluding that the minimum period of care for concrete should be determined by not the time of its curing, but the critical strength, which it gets to the moment of ending of caring. This concrete strength is able to resist various destructive processes.

scholarly journals Efficiency Enhancement of Photovoltaic Module Using An Aluminum Foam Matrix Filled With Phase Change Material (PCM) Under Hot Climate Conditions

2021 ◽  
Author(s):  
Mohamed Sharaf ◽  
Mohamed S. Yousef ◽  
Ahmed Huzayyin
Keyword(s):  
Aluminum Foam ◽  
Electrical Power ◽  
Open Circuit ◽  
Photovoltaic Module ◽  
Pv System ◽  
Average Cell ◽  
Climate Conditions ◽  
Pv Module ◽  
Hot Climate ◽  
Hot Weather

Abstract In the present work, a passive cooling strategy combining an aluminium foam matrix (AFM) with PCM was employed to regulate the temperature of a photovoltaic (PV) system The comparison between three PV modules was established ,the first one was conventional without any changes ,the second one was PV combined with PCM (PV-PCM) and the last one was PV combined with modified PCM which contain an aluminum foam matrix embedded in it (PV-PCM/AFM).Outdoor experiments were carried out in the hot weather of Benha, Egypt, which is situated at latitude 30.466° North and longitude 31.185° East. A comparison of the three PV designs was given and analysed, based on PV surface temperature, PCM temperature, open-circuit voltage, output power generated, and electrical efficiency. It was observed that using composite PCM resulted in better heat absorption from the PV module and better temperature distribution inside the PCM enclosure. Furthermore, the results indicated that against the unmodified PV system, the average cell’s temperature in the PV-PCM system was dropped by 13.3% and its electrical power was enhanced by 9%. Meanwhile, the average cell temperature in the PV-PCM/AFM configuration was reduced by 21.6% while the enhancement of the electrical power was at 14%. Furthermore, the findings demonstrated that, as compared to unmodified PCM, AFM impregnation accelerated the melting of modified PCM by roughly 37%.

scholarly journals Occurrence and Identification of Aspergillus Section Flavi in the Context of the Emergence of Aflatoxins in French Maize

Toxins ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 525 ◽  
Author(s):  
Sylviane Bailly ◽  
Anwar Mahgubi ◽  
Amaranta Carvajal-Campos ◽  
Sophie Lorber ◽  
Olivier Puel ◽  
...  
Keyword(s):  
Global Warming ◽  
Secondary Metabolites ◽  
Climatic Conditions ◽  
Special Focus ◽  
Climate Conditions ◽  
Aspergillus Section Flavi ◽  
Maize Field ◽  
Hot Climate ◽  
Field Samples ◽  
Aspergillus Section

Aflatoxins (AFs) are secondary metabolites produced by Aspergillus section Flavi during their development, particularly in maize. It is widely accepted that AFB1 is a major contaminant in regions where hot climate conditions favor the development of aflatoxigenic species. Global warming could lead to the appearance of AFs in maize produced in Europe. This was the case in 2015, in France, when the exceptionally hot and dry climatic conditions were favorable for AF production. Our survey revealed AF contamination of 6% (n = 114) of maize field samples and of 15% (n = 81) of maize silo samples analyzed. To understand the origin of the contamination, we characterized the mycoflora in contaminated samples and in samples produced in the same geographic and climatic conditions but with no AFs. A special focus was placed on Aspergillus section Flavi. A total of 67 strains of Aspergillus section Flavi were isolated from the samples. As expected, the strains were observed in all AF+ samples and, remarkably, also in almost 40% of AF− samples, demonstrating the presence of these potent toxin producers in fields in France. A. flavus was the most frequent species of the section Flavi (69% of the strains). But surprisingly, A. parasiticus was also a frequent contaminant (28% of the strains), mostly isolated from AF+ samples. This finding is in agreement with the presence of AFG in most of those samples.

Ecological specificities of the interaction between animal breeding and climate changes, caused by greenhouse gas emissions

2017 ◽  
Vol 4 (3) ◽  
pp. 62-72
Author(s):  
O. Zhukorsky ◽  
O. Nykyforuk ◽  
N. Boltyk
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Climatic Conditions ◽  
Animal Breeding ◽  
Gas Emissions ◽  
Climate Conditions ◽  
Emissions Inventory ◽  
Theoretical Substantiation ◽  
Global Problems

Aim. Proper development of animal breeding in the conditions of current global problems and the decrease of anthropogenic burden on environment due to greenhouse gas emissions, caused by animal breeding activity, require the study of interaction processes between animal breeding and external climatic conditions. Methods. The theoretical substantiation of the problem was performed based on scientifi c literature, statistical informa- tion of the UN Food and Agriculture Organization and the data of the National greenhouse gas emissions inventory in Ukraine. Theoretically possible emissions of greenhouse gases into atmosphere due to animal breeding in Ukraine and specifi c farms are calculated by the international methods using the statistical infor- mation about animal breeding in Ukraine and the economic-technological information of the activity of the investigated farms. Results. The interaction between the animal breeding production and weather-and-climate conditions of environment was analyzed. Possible vectors of activity for the industry, which promote global warming and negative processes, related to it, were determined. The main factors, affecting the formation of greenhouse gases from the activity of enterprises, aimed at animal breeding production, were characterized. Literature data, statistical data and calculations were used to analyze the role of animal breeding in the green- house gas emissions in global and national framework as well as at the level of specifi c farms with the consid- eration of individual specifi cities of these farms. Conclusions. Current global problems require clear balance between constant development of sustainable animal breeding and the decrease of the carbon footprint due to the activity of animal breeding.

scholarly journals Relationship between Relative Maturity and Grain Yield of Maize (Zea mays L.) Hybrids in Northwest New Mexico for the 2003–2019 Period

Agriculture ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 290
Author(s):  
Koffi Djaman ◽  
Curtis Owen ◽  
Margaret M. West ◽  
Samuel Allen ◽  
Komlan Koudahe ◽  
...  
Keyword(s):  
New Mexico ◽  
Grain Yield ◽  
Sprinkler Irrigation ◽  
Growing Season ◽  
Climatic Conditions ◽  
Agricultural Science ◽  
Production Optimization ◽  
Science Center ◽  
Early Season ◽  
Climate Conditions

The highly variable weather under changing climate conditions affects the establishment and the cutoff of crop growing season and exposes crops to failure if producers choose non-adapted relative maturity that matches the characteristics of the crop growing season. This study aimed to determine the relationship between maize hybrid relative maturity and the grain yield and determine the relative maturity range that will sustain maize production in northwest New Mexico (NM). Different relative maturity maize hybrids were grown at the Agricultural Science Center at Farmington ((Latitude 36.69° North, Longitude 108.31° West, elevation 1720 m) from 2003 to 2019 under sprinkler irrigation. A total of 343 hybrids were grouped as early and full season hybrids according to their relative maturity that ranged from 93 to 119 and 64 hybrids with unknown relative maturity. The crops were grown under optimal management condition with no stress of any kind. The results showed non-significant increase in grain yield in early season hybrids and non-significant decrease in grain yield with relative maturity in full season hybrids. The relative maturity range of 100–110 obtained reasonable high grain yields and could be considered under the northwestern New Mexico climatic conditions. However, more research should target the evaluation of different planting date coupled with plant population density to determine the planting window for the early season and full season hybrids for the production optimization and sustainability.

Experimental study of an earth to air heat exchanger (EAHE) for warm humid climatic conditions

Geothermics ◽  
2020 ◽  
Vol 84 ◽  
pp. 101741 ◽  
Author(s):  
H.P. Díaz-Hernández ◽  
E.V. Macias-Melo ◽  
K.M. Aguilar-Castro ◽  
I. Hernández-Pérez ◽  
J. Xamán ◽  
...  
Keyword(s):  
Experimental Study ◽  
Heat Exchanger ◽  
Climatic Conditions
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