Physical Sciences and Engineering

Made n- and p-type Si0.7Ge0.3 thermoelectric alloys and their thermoelectric characteristics are studied. These alloys are cut into profiled plates, monolithic packages are assembled from them, switching plates are glued to the lower and upper bases of the packages, commutated packages are cut into 4-5 mm thick plates and monolithic thermoelectric modules are assembled from them. Electrical insulation nodes of thermoelectric modules are made on the basis of AlN and graphite plates. These nodes are connected to modules, resulting in monolithic samples.

An experimental study was carried out on an indirect solar dryer operating with natural convection. The study focused on the behavior of three parameters over time. Solar radiation at the measurement site, the temperature of various elements of the collector and of the air at four precise locations inside the dryer, and the velocity at its outlet were measured. The results of the five-day average measurements showed that the solar dryer has a uniform temperature profile inside the drying chamber.

The study was conducted to evaluate the psychometric properties of the Bengali version of the Multidimensional Students’ Life Satisfaction Scale (MSLSS: Huebner, 1994) within a sample of 576 Bengali school-going adolescents in grades 9 to10. The first objective was to determine the construct validity of the MSLSS with school-going adolescents using exploratory factor analysis (EFA). Eight items were eliminated during the factor analysis. The results clearly support the five-factor structure as a replication of Huebner’s five-factor model.

The study aims to investigate the ability of biological treatment of raw tannery effluent by using Pongamia glabra bark powder to decolourize tannery wastewater contaminants in terms of heavy metal removal capacity and efficiency and to check their ability to decolorize and to degrade the toxic chemical components of the tannery effluent at various concentration and pH.

The evaluation of the material strength of concrete over time is a significant concern in many civil engineering construction projects. Several reference documents, including BAEL 91, provide formulas to estimate the compressive strength of concrete at J days based on the strength measurements obtained at 7 days. However, noticeable differences exist between the estimated values and the actual values obtained during construction when applying these formulas.

The routing protocol of nodes in RPL networks will now use a safe blockchain-based authentication system, according to this study. The Ethereum blockchain and smart contracts are used in the suggested approach to address the security issues, notably Decreased Rank At-tack in RPL network topology. The background of RPL, IoT-LLNs, and blockchain technology is covered in the study, along with the suggested methodology and its application. The study also assesses the performance of the suggested remedy and contrasts it with current approaches.

Biometric authentication is now widely utilised as an alterna-tive to passwords on IoT devices such as smartphones. However, present biometric systems are subject to spoofing attacks. Several liveness detec-tion techniques have been presented to determine whether a live person or an artificial duplicate is in front of the biometric sensor. However, the challenge remains unsolved due to the difficulty in identifying discrimina-tive and computationally affordable traits for spoofing attacks.

Les échanges des biens et services constituent le dénominateur des activités socio-économiques pour les Etats. Ainsi donc le commerce international des produits de base est l’un des échanges que fait de la République Démocratique du Congoavec les autres Etats Membres de l’Organisation Mondiale du Commerce. Sans peur d’être contredit, tout est démontré dans cet article que le négoce des produits de base de la RDC demeure défavorable pour le développement durable de la population congolaise. Face à cela, la thèse de la malédiction des matières premières est amplement confirmée.

The construction of infrastructure capable of withstanding future hazards in the Akpakpa district requires good control of the foundation soils. The test results showed that the Ayélawadjè and Sodjèatimey soils are class D according to the GTR classification and sub-class D1 (VBS<0. 1): insensitive to water, weakly organic and presenting an over-consolidated state, while the Avotrou soils are of class A according to the GTR classification and of sub-class A4 (IP>40%): very plastic with the following main characteristics: very coherent and almost impermeable.

The Bongor region, located between 10°12' and 10°20' North latitude and 15°22' and 15°34' East longitude, is part of the quaternary aquifers of Chad. It has potential in water resources but knowledge of its hydrodynamic and hydrogeochemical functioning remains insufficient. Thus, this study aims to gain knowledge of the hydrogeochemistry of groundwater in the Bongor area and its surroundings.