All Articles

Summary: A model of a single-server queuing-inventory system (QIS) with a limited waiting buffer for consumer customers (c-customers) and catastrophes has been developed. When a catastrophe occurs, all items in the system’s warehouse are destroyed, but c-customers in the system are still waiting for replenishment. In addition to c-customers, negative customers (n-customers) are also taken into account, each of which displaces one c-customer (if any). The policy (s, S) is used to replenish stocks. If, when a customer enters, the system warehouse is empty, then, according to Bernoulli’s trials, this customer either leaves the system without goods or joins the buffer. The mathematical model of the investigated QIS is constructed in the form of a continuous-time Markov chain (CTMC). Both exact and approximate methods for calculating the steady-state probabilities of constructed CTMCs are proposed and closed-form expressions are obtained for calculating the performance measures. Numerical evaluations are presented, demonstrating the high accuracy of the developed approximate formulas, as well as the behavior of performance measures depending on the input parameters. In addition, an optimization problem is solved to obtain the optimal value of the reorder point to minimize the expected total cost.

Summary: The essay focuses on the problems that hindered the ghazal genre from developing and how the poet kept the tradition alive in Azerbaijani literature at the start of the 20th century. We used Aliagha Vahid's literary creativity for our project since he lived through this period in Azerbaijan, experienced all of its hardships, and demonstrated the genre's potential by creating poetic imagery of the time in his ghazals. He is an Azerbaijani poet who is revered in the Turkic community as Fuzuli's successor and is credited with saving the ghazal genre in Azerbaijani literature. Analyzing his lyrics provided excellent possibilities to examine the influential factors on all of the Azerbaijani literature at the time. In the study, his creation of new kinds of ghazals with social and political issues while retaining the characteristics of the traditional ghazal genre was investigated. With him, the genre in Azerbaijani literature underwent a new phase. The attempt to eradicate the ghazal from the Azerbaijani literature which has a history of centuries-long history did not succeed as a result of mostly Aliagha Vahid's serious efforts. For this purpose, the poet's historical milieu, the challenges of the repression, his satirical ghazals with a sociopolitical theme, the thematic details of his lyrics, and other issues have been involved in the investigation.

Summary: The electrical and photoelectric properties of anisotype n-Si−p-GaSe heterojunctions obtained as a result of the deposition of a GaSe thin layer on a cold n-Si single crystal substrate by the thermal evaporation method were studied. It was determined that the height of the potential barrier in thermal annealing structures at T = 200°C during t = 3 hours occurs due to the decrease in the density of states of local levels located near the Fermi level in the amorphous layer. The mechanism of photosensitivity in an isotype heterostructures was analyzed and it was found that the photosensitivity of the heterojunction increases as a result of a decrease in the surface density of state at the contact boundary of the components, by thermal means. The spectral distribution of the quantum efficiency in the n-Si – p-GaSe heterojunction was studied and their perspective was determined.

Summary: The radiation oxidation of Be in water at room temperature in the absorbed dose range Dγ = 0.5…180 kGy was studied by radiothermoluminescence (RTL), infrared reflection-adsorption spectroscopy (IRRAS), and electrical conductivity. The participation and role of surface relaxing intermediate-active particles in the dynamics of changes in the oxidation process are considered. Using the RTL method, the role of surface oxygen hole centers generated by γ-irradiation and chemisorbed oxygen in the formation of nanooxide films was experimentally established. The formation of nanooxide films on the surface of Be in water was traced in the IR reflection spectra. The kinetics of radiation oxidation of beryllium has been studied and its radiation passivation has been established. According to the logarithmic dose dependence of the surface resistivity Be, two stages of the oxidation process were revealed. It is shown that the formation of nano oxide films leads to a decrease in the surface electrical conductivity of beryllium by 2 orders of magnitude and an increase in the thickness of oxide films by 1.6 times.