Study on the Oxygen Enrichment Effect of Individual Oxygen-Supply Device in a Tunnel of Plateau Mine

Complex characteristics of the plateau environment such as low oxygen content seriously restrict the exploitation of abundant mineral resources in plateau areas. To regulate the hypoxia environment and improve the comfort of workers engaged in intense physical labor like tunnel excavation operations in plateau mines, an individual oxygen-supply device for tunnel of plateau mine was proposed to create local oxygen enrichment in the area around the human nose. The Computational Fluid Dynamics (CFD) method was used to judge the application’s effect of the individual oxygen-supply device in plateau mine, revealing the oxygen diffusion law under the influence of different oxygen enrichment factors. The orthogonal design and range analysis were used to measure the degree of influence of major factors such as oxygen-supply velocity, oxygen-supply concentration, and tunnel airflow velocity. The results demonstrate that the oxygen mass fraction of the air inhaled by the human had a positive correlation exponential function, a positive correlation linear function, and a negative correlation exponential function, respectively, concerning oxygen-supply velocity, oxygen-supply concentration, and tunnel airflow velocity. The range analysis revealed that the major influencing factors of oxygen enrichment in the tunnel of the plateau mine were, in a descending sequence, as follows: oxygen-supply concentration, tunnel airflow velocity, and oxygen-supply velocity, and the corresponding ranges were 2.86, 2.63, and 1.83, respectively. The individual oxygen-supply device achieved the best oxygen enrichment effect when the oxygen-supply velocity was 5 m/s, the oxygen-supply concentration was 60%, and the tunnel airflow velocity was 0.2 m/s, which increased the oxygen mass fraction of air inhaled by the human to 30.42%. This study has a positive guiding significance for the improvement of the respiration environment in the tunnel of plateau mine.

Performance of capillary ceiling cooling panel on ceiling surface temperature and indoor thermal environment

A new experimental methodology is presented to show the effect of water supply temperature, mass flow rate and thermal load distribution on the radiant ceiling capacity and thermal comfort conditions. Computerized fluid dynamics simulated vertical temperatures and velocities profiles were validated by a comparison with experimental results and the difference was within 10%. Uniform surface temperature distribution was achieved in a 45.6 m3 test room installed with capillary ceiling radiant cooling panels by an increase in water temperature and air supply velocity. When the ventilation system was turned off, the mean ceiling surface temperature rose from 16.9 ± 0.4°C to 21.5 ± 0.3°C with a rise in the inlet water temperature to 20.1°C. The temperature difference between the head and ankle of an occupant was 2.0°C, which complies with the Chinese standard, GB/T 18049-2017. At a height of 1–1.5 m, the maximum temperature fluctuation was 2°C in the horizontal direction. When the ventilation system was turned on, with the air supply temperature and velocity at 19.8°C and 1.11 m s−1, the ceiling surface temperature was increased by 0.5°C. The indoor air temperature has a positive correlation with the air supply temperature and internal heat load but a negative correlation with air supply velocity.

The Use of Sensors for Monitoring the Feeding Process and Adjusting the Feed Supply Velocity in Fish Farms

Aquaculture is a growing industry, and its sustainability is crucial. One of its major environmental impacts is the uneaten feed that pollutes the water. To minimize the uneaten feed, many systems have been developed. Nevertheless, current systems can be improved by considering the fish position in the tank and the falling feed. In this paper, we propose a system based on fish presence sensors set at different tank heights and a feed detection sensor located in the drainage tubes. The fish presence sensor is based on light-dependent resistor (LDR). The calibration of these sensors is shown. When the output voltage is higher than 1.467 V, we can consider that fish are present. On the other side, the falling feed sensor is based on a CMOS sensor. The calibration process is performed with 40 pictures. The summation of pixels, with brightness value between 0 and 15 in the blue histogram, is used as an indicator of feed presence. If this value is higher than 520 pixels, we can consider that there is feed in the picture. Moreover, a verification process of both sensors is done. The results of the verification confirm the calibration. Finally, the operation of the system is shown.

Dynamics of the Formation of Protection for Circulatory Bed in Bone Regenerate

Evaluation of the bone regenerate maturation in 21 patients, aged 27 – 66 years, with closed shoulder fractures was performed in the course of treatment by Ilizarov technique according to the rate of blood supply velocity at functional load and by the value of that load. Examination was performed in 1 and 2 weeks as well as in 1 and 2 months after fixation. Within the first 2 weeks the bone fragments micro mobility at 10 kgF axial load on the extremity made up 194±42 µm. Subsequently as the regenerate became compact the bone fragments micro mobility decreased up to 53±13 µm (p≤0.02). During the fixation period the load tolerance increased from 5 to 15 kgF. The threshold of load tolerance was detected by the occurrence of unpleasant feelings the regenerate zone and increased rate of blood circulation in the vessels. At the end of fixation period the rate of blood circulation was decreased by 2 times and practically did not change at increasing loads confirming the formation of the protection system for circulatory bed in the bone regenerate.