Showing 6 results for Afzalian
Volume 16, Issue 4 (7-2017)
Abstract
Supervisor reduction procedure can be used to construct the reduced supervisor with a reduced number of states in discrete-event systems. However, it was proved that the reduced supervisor is control equivalent to the original supervisor with respect to the plant; it has not been guaranteed that the reduced supervisor and the original one are control equivalent under partial observation. In this paper, we extend the supervisor reduction procedure by considering partial observation; namely not all events are observable. A feasible supervisor which is constructed under partial observation becomes reduced based on control consistency of uncertainty sets of states, instead of the original supervisor. In order to construct a partial observation reduced supervisor, a partial observation control cover is constructed based on control consistency of uncertainty sets in the supervisor. Four basic functions are defined in order to capture the control and marking information on the uncertainty sets. In the resulting reduced supervisor, only observable events can cause state changes. The results are illustrated by some examples.
Seyed Alireza Zolfaghari, Mahdi Afzalian,
Volume 16, Issue 13 (Conference Special Issue 2017)
Abstract
Mahdi Afzalian, Farzin Davodi, Hassan Hassanzadeh, Seyed Alireza Zolfaghari, Mahdi Maerefat,
Volume 17, Issue 2 (3-2017)
Abstract
Thermal sensation evaluation of occupants in a dense occupancy space can be an effective step for designing ventilation systems of these environments. In a dense occupancy environment, because of the presence of a large population and also differences in personal parameters such as age, gender, clothing, weight, and body mass index, providing the appropriate thermal comfort conditions is complicated. In this study, the individual characteristics effects on thermal comfort conditions of occupants in a dense occupancy environment is investigated by individualized three-node model. For this issue, a dense occupancy environment with displacement ventilation and inlet air diffusers on the floor is modeled and thermal sensation index for occupants who seated in middle row has been analyzed. Based on the results, the women are more sensitive than men under cold conditions. Also, effects of mass body index on thermal sensation are significantly noticeable. Compared with a healthy person, the thinner people have a cold sensation and fatter ones feel warmer. For example, in the mentioned case, difference between thermal sensation index of thin woman and obese man is 0.42 for the bare parts of the body, indicating noticeable effects on thermal sensation.
Mahdi Afzalian, Seyed Alireza Zolfaghari, Ali Foadadini,
Volume 17, Issue 2 (3-2017)
Abstract
Nowadays, the building ventilation is an essential process, due to need of improving the air quality and thermal comfort conditions for occupants. Providing the mentioned conditions is more complex for crowded and larger spaces. In this study, the effects of air change rate per hour (ACH) on thermal comfort, indoor air quality and energy consumption in an amphitheater with under floor air distribution system have been investigated by using the computational fluid dynamics and Open Foam numerical solver. For this issue, an amphitheater with 50 occupants has been modeled under the conditions that the air inlet diffusers located in front of seats. Also, the air change rate per hour is assumed to be 5, 10 and 15. For better comparison between the results, inlet air temperature is controlled until the mean of thermal comfort index (TSENS) in the occupied zone equals to zero. The results indicate that for air change rates of 15, 10 in comparison with ACH of 5, the CO2 concentrations in the occupied zone are respectively reduced about 36 and 46 percent and so the indoor air quality is improved. On the other hand, the energy consumption is increased about 28 and 69 percent, respectively. Also, based on the results, by increasing the ACH rate, the draft local discomfort is significantly increased and can be reached at the amount of 15%.
Volume 18, Issue 112 (May 2021)
Abstract
White button mushrooms (Agaricus Bisporus) have significant nutritional value, but due to high moisture content, they need special treatments to increase the storage time. Drying increases, the shelf life of the product by reducing microbial activity, weight, and volume of products and it causes to pack, transport and store of products easier. IN this study, using the osmotic treatment, three types of sugars Liquorice, white sugar, and red sugar in three concentrations of 40, 50, and 60% and three temperatures of 25, 32.5, and 40 °C to reduce heat damage to the index qualities such as samples color, reducing drying time and energy consumption and increasing process efficiency in supplementary drying which has done by hot air. According to the findings, among the treatments, Liquorice had the highest rate of moisture loss (89.24 in 132 minutes), solids adsorption (10.38%), and discoloration ( ϱ = 388.470) and the lowest rate of wrinkling (63.51%). The highest rehydration rate was related to white sugar (at 25. C, 2.91 gr/gr, and 40% concentration was 2.82 gr/gr). The microbial test did not show a significant effect on the overall counting of the colonies, and no mold or yeast was observed in any of the samples.
M. Taheri, M. Afzalian, S.a. Zolfaghari, H. Hassanzadeh,
Volume 19, Issue 12 (December 2019)
Abstract
Particle pollutants in the indoor environment are a serious threat to human health. Therefore, it is necessary to recognition, investigation, and controls of the distribution of these particles in the indoor environment. In the present research, the effect of air inlet angle of swirling diffusers in UFAD systems has been investigated on micron particles pattern distribution by considering the thermal comfort condition. For analyzing the fluid flow and particle distribution, the development of OpenFoam solver by the Eulerian-Lagrangian method has been used. The two-node model of Gauge has been used for predicting the thermal comfort conditions. Inlet angles are set in three cases of 30, 45 and 60. Based on the results, in all three cases, the TSENS index is in the thermal comfort zone. However, by changing the swirling angle from 30 to 60, the vertical temperature difference can be reduced about 1℃. Investigation of changing the inlet angle shows that at inlet angle of 30 and 60 degrees, the percentage of particles exited with 2.5 micrometers diameter were 32% and 55% of the total particles, respectively. In other words, increasing the inlet air angle can lead to exit more amount of any size of particles from the room. In addition, by increasing particles size, larger particles removed faster from the breathing zone, and smaller particles will remain longer time in the air. Therefore, smaller particles have a greater impact on indoor air quality.
