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Abstract

Using alternative fuels (AF) in industry high consuming energy where fossil fuels are largely consumed may be a great solution to decrease CO2 emission and cost production. Or, when using these alternative fuels, the combustion may be difficult to control regarding the different components of AFs compared to fossil fuels. In this case, the use of the computational fluid dynamics CFD tools is a great solution to predict the AFs combustion behavior. This paper represents a computational study of petcoke and olive pomace (OP) co-combustion in a cement rotary kiln burner, established on the commercial CFD software ANSYS FLUENT. This study presents a useful key to choose an adequate simulation model that well predicts co-combustion problems. The performance of the K-ϵ turbulence models varieties (standard, Realizable, and Re-Normalization Group) combined with the hybrid finite rate/eddy dissipation model and the simple eddy dissipation model for predicting the co-combustion characteristics was investigated. The particle phase solutions are obtained using the Lagrangian approach. The performance of the mentioned model was evaluated based on the mesh accuracy, convergence time, temperature shape, and important chemical elements concentration. The predicted values of species concentrations and temperature are compared to the results obtained from the real case study and available literature. The standard K-ϵ model combined with the hybrid finite rate/eddy dissipation model gives the best results and the lower computational resources required for the 2-D model realized.

Open access

Abstract

Climate change has become a real challenge in different fields, including the building sector. Understanding and assessing the impact of climate change on building energy performance is still necessary to elaborate new climate-adaptive design measures for future buildings. The building energy consumption for heating and cooling is mainly related to the building envelope thermal performance. In this study, the winter heat loss and summer heat gain indicators are proposed to assess and analyse the potential impact of climate change on opaque building envelope elements for different climate zones in Morocco over the next 40 years. For that purpose, a one-dimensional heat transfer model is used to simulate the heat transfer through the multi-layer structure of the wall/roof. A medium climate change scenario is considered in this study. The results showed that the current average walls and roof summer heat gain is expected to increase of about 19.2–54.3% by the 2060s depending on the climate zone, versus a less important decrease in winter heat loss varies between –10.6 and –20.6%. This paper provides a reliable evaluation of the climate change impact on building envelope thermal performance, which leads to better adjustments in future building envelope designs.

Open access

Urban Transformations of Kharkiv’s Large Housing Estates •

Novi Budynky and Pavlovo Pole After 1991

Harkov nagy lakótelepeinek városépítészeti átalakulása •

Novi Budynky és Pavlovo Pole 1991 után
Építés - Építészettudomány
Authors: Hlib Antypenko, Nadiia Antonenko, and Katherine Didenko

Kharkiv is the second largest city of Ukraine with a unique history of urban housing development. In the 20th century it became a field of large housing construction. More than 10 large housing estates were constructed in the period between the second half of 1950s–late 1980s following the Soviet method of prefabricated construction, which was introduced into urban planning in connection with the radical change of all architectural and construction activities in the USSR. This paper explores factors of post-socialist urban development (after the change of political regime in Ukraine in 1991) of the case study large housing areas. For the purpose of the study, two Kharkiv large housing areas were selected – Novi Budynky and Pavlovo Pole, which were designed and built in the same period (late 1950s) and were the first residential areas of Kharkiv built according to the new planning principles of Soviet prefabricated construction. Pavlovo Pole is a large housing estate located not far from the historic center regarded as a good quality housing area, intended for the Soviet “intelligentsia” while Novi Budynky is often a stigmatized area constructed mainly for the factory workers.

Key research questions are: description of the history of construction and development of Pavlovo Pole and Novi Budynky large housing estates; comparison of the specific features of their design and construction; to determine how these large housing estates are connected with the rest of the city spatially and in terms of socio-cultural aspect, in particular with the city center; to identify the reasons and content of key urban transformations in the large housing areas, such as: demolition of houses and new construction, reduction of the area of public recreational function, appropriation of deserted areas, etc.

Harkov Ukrajna második legnagyobb városa, amely egyedülálló történettel rendelkezik a városi lakásfejlesztés területén. A 20. században nagy lakásépítkezések zajlottak: az 1950-es évek második fele és az 1980-as évek vége közötti időszakban több mint 10 nagy lakótelep épült Harkovban az előregyártott építés szovjet módszerét követve, amelyet a Szovjetunióban az összes építészeti és építési tevékenység radikális változásával összefüggésben vezettek be a várostervezésbe. Ez a tanulmány az 1991-es ukrajnai rendszerváltás utáni posztszocialista városfejlesztés tényezőit vizsgálja két harkovi nagy lakótelepen. Novi Budynky és a Pavlovo Pole, a város első nagy lakótelepei, melyeket az 1950-es évek végén terveztek és építettek a szovjet előregyártott építés új tervezési elveinek megfelelően. Pavlovo Pole a történelmi központhoz közeli, ma is jó minő-ségű lakóterületnek tekinthető, amit a szovjet „értelmiségnek” szántak, míg Novi Budynky gyakran stigma-tizált városrész, amelyet elsősorban a gyári munkásoknak építettek.

A legfontosabb kutatási kérdések a következők: Pavlovo Pole és Novi Budynky nagy lakótelepei építésének és fejlődésének története; tervezésük és kivitelezésük sajátosságainak összehasonlítása; annak meghatározása, hogy ezek a nagy lakótelepek hogyan kapcsolódnak a város többi részéhez, különösen a városközponthoz térben és társadalmi-kulturális szempontból; a nagy lakóövezetekben zajló, kulcsfontosságú városi átalakulások okainak és tartalmának azonosítása, mint például: házak bontása és új építés, a nyilvános rekreációs területek csökkentése, elhagyatott területek kisajátítása stb.

Restricted access

Abstract

In this study, a single stage thermoelectric cooler (TER, of size: 21 × 14.2 × 13.5 cm) with thermoelectric module (TEM, of type inbc1-127. 05 with size 40 × 40 × 4.0 mm) and applied electrical power of 30 W and current of 2.5 A, was adopted to estimate the coefficient of performance (COP) of thermoelectric refrigerator (TER). The TER uses a fan to cool the heat exchange region of the TEM. The temperature of the fruit/vegetable samples used in this study was taken before and after cooling for a specific period. The temperatures at both the hot and cold sides of the TEM were also taken at every specific cooling period. The experimented TER can cool vegetable/fruit from about 27 to 5°C within 3 h. The aim of this study is to determine the COP of TER to ascertain the possible applications. The temperature gradient at the heat exchange section of TEM was used to estimate the average theoretical COP to be 0.99, the heat extracted from the cooling chamber and the power supplied was used to estimate the average practical cooling COP to be 0.52; which is within 0.4–0.7 standard COP for a single stage type of TER.

Open access

Abstract

Raw materials requirement is foremost necessary in construction sector. Due to the increase in construction activities, the raw material utilization is also increased, which may lead to depletion of the resources. The usage of M sand also increases day by day. On the other side, waste disposal is posing a major threat to environment and human health. This paper shows the investigation carried out in manufacturing fly ash bricks made by utilizing vermicompost as an alternative material for M sand, the physical and chemical properties of M sand and vermicompost are studied and they seem to be the same. In this study, an attempt is made to check the feasibility of replacement of vermicompost for M sand in brick making. The brick specimens are casted as per the mix proportions and they are tested for strength and durability at the age of 28 days. It has been identified that the vermicompost replacement at 5% and 10%, the compressive strength of the brick is 7.90 and 7.31% respectively, which is found to be nearer to the strength of the control specimen and the water absorption for all the mixes of the brick casted were below 20% as per IS code. Inclusion of vermicompost in the fly ash bricks will tend to reduce the use of M sand.

Open access

Abstract

Digital technologies had an effect on people's lives. The majority of these digital devices rely on cloud storage to meet their memory needs. Hundreds of thousands of images, videos, and audio files are being transferred to cloud storage. Thousands of people around the world access these media every second. Unauthorized access to these media must be avoided. One of the weak points for data breaches is the user-end encryption. This paper suggests a strategy for improving cloud data protection by combining the AES and blowfish encryption and decryption algorithms. AES-256 is used as the first layer, followed by blowfish as the second layer, in the hybrid solution. The output of the first layer is input to the second layer and the final result is analyzed. The proposed method also discusses other combined approaches such as AES with other traditional algorithms but the proposed method gives significant results compared to other approaches.

Open access

Abstract

Adenosine triphosphate (ATP) is an energy compound present in living organisms and is required by living cells for performing operations such as replication, molecules transportation, chemical synthesis, etc. ATP connects with living cells through specialized sites called ATP-sites. ATP-sites are present in various proteins of a living cell. The life span of a cell can be controlled by controlling ATP compounds and without the provision of energy to ATP compounds, cells cannot survive. Countless diseases treatment (such as cancer, diabetes) can be possible once protein active sites are predicted. Considering the need for an algorithm that predicts ATP-sites with higher accuracy and effectiveness, this research work predicts protein ATP sites in a very novel way. Till now Position-specific scoring matrix (PSSM) along with many physicochemical properties have been used as features with deep neural networks in order to create a model that predicts the ATP-sites. To overcome this problem of complex computation, this exertion proposes k-mer feature vectors with simple machine learning (ML) models to attain the same or even better performance with less computation required. Using 2-mer as feature vectors, this research work trained and tested five different models including KNN, Conv1D, XGBoost, SVM and Random Forest. SVM gave the best performance on k-mer features. The accuracy of the created model is 96%, MCC 90% and ROC-AUC is 99%, which are the same or even better in some aspects than the state-of-the-art results. The state-of-the-art results have an accuracy of 97%, MCC 78% and ROC-AUC is 92%. One of the benefits of the created model is that it is much simpler and more accurate.

Open access

Abstract

Scarcity of the construction materials, peculiarly the natural river sand has become a serious threat in the construction industry. Though many researchers of developed and developing countries are trying to find alternative sources for the same, the complete replacement of the fine aggregate in concrete is crucial. Geopolymer sand developed from the Industrial waste (Ground granulated blast furnace slag - GGBS) is an effective alternative for the complete replacement of the natural sand. The GGBS based geopolymer sand (G-GFA) was tested for physical and chemical properties. Upon the successful achievement of the properties in par with the natural river sand, the fresh properties (fresh concrete density & slump) and hardened properties (compressive strength, tensile strength & flexural strength) of the concrete specimens developed with G-GFA were studied. The G-GFA is obtained by both air drying (AD-G-GFA) and oven drying (OD-F-GFA) after the dry mixing of the alkaline solution and GGBS for about 10 min. Thus, developed fine aggregates were studied separately for the fresh and hardened concrete to optimize the feasible one. Superplasticizer of 0.4% is included in the concrete mix to compensate the sightly hydrophilic nature of the fine aggregates produced. The mechanical properties of the concrete with G-GFA are observed to be more than 90% close to that of the concrete developed with natural river sand. Thus, both the fresh and mechanical properties of the G-GFA concrete specimens resulted in findings similar to those of the control specimen developed with natural river sand reflecting the plausibility of G-GFA as a complete replacement choice to the fine aggregate in the concrete industry. The flaky GGBS particles merge well with the alkaline solution at room temperature itself since the former gets dried at elevated temperatures. Thus, more feasible fresh concrete properties and mechanical properties were recorded for the AD-G-GFA than the OD-G-GFA.

Open access

Abstract

Construction industry is one of the biggest sectors globally and a wide variety of materials are used to carry out various works. Particularly, cement is a material that is used in the construction of various structures and it is also the major source of emission of CO2 gas into the atmosphere which results in global warming. Many researchers have identified various replacement materials for cement as a partial substitution and carried out experiments successfully. Nano silica is widely utilized as a partial replacement for cement and a lot of research is carried out. This paper reviews the past studies in which nano silica is utilized in various building materials such as cement mortars, normal concrete and special concretes. The fresh concrete properties, strength and durability of the material are the parameters reviewed and it is apparent that by incorporating nano silica in cement it absorbs more water, which makes the mix less workable and it imparts additional strength to the concrete and also provides better durability when compared with the control specimen. Hence it has been revealed that nano silica will be a good replacement for cement as it is pozzolanic in nature and also possessing good microstructure.

Open access

Abstract

Our study aims to discover what reasons justify the physical activity of fitness consumers, and how the motivation of this physically active group can be maintained, which then may contribute to maintain a healthy society in the long run. Of the primary research procedures we chose to use the questionnaire survey method. We used cluster analysis for which we used principal components that were created with factor analysis to determine what groups can be established based on responses to the questions related to motivation and the factors that influence their choices of facilities. Based on the rank order of motivations influencing attendance of fitness sessions, fitness consumers were stratified into four different clusters. Then, segmentation of the consumers was done based on the factors influencing their choices of facilities. Our results lead to the conclusion that the motivation of consumer groups identified in our research can be sustained in the long run, the less active groups can be better involved and attracted to sports offered by fitness centres, on condition the fitness studios reliably serve these needs and provide the expected variety of services and hygienic conditions.

Open access