Tribolumen: A Tribometer for A Correlation Between AE Signals and Observation of Tribological Process in Real-Time—Application to A Dry Steel/Glass Reciprocating Sliding Contact

This paper deals with the development of an original apparatus called TRIBOLUMEN designed specifically for friction experiments on transparent materials. The friction measurement is synchronized with an acoustic emission (AE) sensor and the device is also equipped with a high-speed camera offering a direct view at the interface to gain a deeper understanding of tribological mechanisms. The TRIBOLUMEN device is in ball-on-flat contact configuration with a range of strokes from 5 to 500 µm and an oscillation frequency from 5 to 600 Hz. The experiments showed that this device has an adequate rigidity and can detect subtle friction modifications of the oscillating contacts. The observation of a steel-on-glass contact in real-time highlighted the initiation of Hertzian cracks followed by the formation of debris in the contact. Using the synchronous measurement, these mechanisms were clearly associated with different stages in the friction measurement and in the AE signals, which permitted to identify the AE signature of Hertzian cracks.

Cement Mortar Porosity by Modified Analysis of Differential Scanning Calorimetry Records

A modified method of interpreting a heat flux differential scanning calorimetry records in pore structure determination is presented. The method consists of determining the true phase transition energy distribution due to the melting of water during a differential scanning calorimetry (DSC) heating run. A set of original apparatus functions was developed to approximate the recorded calorimetric signals to the actual processes of the water phase transition at a given temperature. The validity of the proposed calorimetric curves-based algorithm was demonstrated through tests on a cement mortar sample. The correct analysis required taking into account both the thermal inertia of the calorimeter and the thermal effects that are associated with water transitions over the fairly narrow temperature ranges close to 0 °C. When evaluating energy distribution without taking the shifts of the proposed modified algorithm into account, the volume of the pores with radii bigger than 20 nm was greatly overestimated, while that of the smaller pores (rp < 20 nm) was underestimated, in some cases by approximately 70%.

Bitumen Foaming Optimisation Process on the Basis of Rheological Properties

This article discusses the results of bitumen foam properties optimisation with respect to three factors: air pressure, bitumen temperature and amount of water. The test materials were unmodified bitumen 50/70 and bitumen 50/70 modified with 2.5% synthetic wax. The experiment was designed according to the 3(3−1) fractional factorial design. The distribution of parameters of bitumen foam were measured with the authors’ original apparatus using a laser beam. This measurement method increased the accuracy of maximum expansion ratio (ER) and half-life (HL) estimation. Based on HL and ER results, it was found that the foaming process increased bitumen stiffness due to the dynamic ageing of the bitumen. The experimental design allows more effective control over the properties of foamed bitumen with respect to its intended use. The presence of synthetic wax extended the half-life of the bitumen foam.

Study on the Underwater Rotating Apparatus with Changeable Rotating Angle

We proposed the underwater rotating apparatus with changeable rotating angle for the FDSO bottom construction, which includes a pair of arc-shaped base, the hydraulic support, the arc-shaped hydraulic rail, the driving motor, power supply units and the computer. The underwater rotating angle mathematical model was built with the known bottom block division. The apparatus has the features of changeable underwater rotating angle, nondestructive to the FDSO bottom and the semi-submersible barge, low labor intensity when compared with the original apparatus. Finally, the underwater rotating apparatus was successfully applied to build the Sevan Driller FDSO bottom, and the results show the model is correct and valid, which provides an important reference for the FDSO construction.

Experimental investigation of operating and dynamic properties of adsorption filter prototype

The aim of the paper is an examination of flow-thermal, operating and dynamic properties (velocities of gas mixture, flows, pressure drops, temperature, humidity, chemical pollutants tests, and efficiency) and performance of the adsorption filter prototype in the filter-ventilation system. The paper presents the results of the experimental research conducted on the original apparatus in the laboratory for air quality management at the Faculty of Occupational Safety in Nis. The examination of flow-thermal, operating and dynamic parameters of the observed filter prototype was carried out on an experimental ventilation setup with a variable flow rate of gas mixture. Experimental data were registered with appropriate measuring equipment, which helped us obtain a picture of the behavior of the adsorption filter prototype compared to simulated parameters of the gas mixture. By measuring and data acquisition, we reached the assumptions for identifying the observed process, and thus the possibility of modeling and controlling process parameters.

Exposure to pressure stimulus enhances succinate dehydrogenase activity in L6 myoblasts

Contraction of skeletal muscle generates pressure stimuli to intramuscular tissues. However, the effects of pressure stimuli, other than those created by electricity or nerve impulse, on physiological and biochemical responses in skeletal muscles are unknown. The purpose of this study is to examine the effects of a pure pressure stimulus on metabolic responses in a skeletal muscle cell line. Atmospheric pressure was applied to L6 myoblasts using an original apparatus. Succinate dehydrogenase (SDH) activity was evaluated by colorimetric assay using tetrazolium monosodium salt. The amounts of 2-deoxy-[3H]glucose uptake and lactate release were measured. SDH activity was 2.6- to 2.9-fold higher in pressurized L6 cells than in nonpressurized L6 cells ( P < 0.01), and 2-deoxy-[3H]glucose uptake was 2.2-fold higher ( P < 0.001). In addition, the amount of released lactate decreased from 6.8 to 3.7 μmol/dish when pressure was applied ( P < 0.001). In contrast, the intracellular lactate contents of the pressurized cells were higher than those of nonpressurized cells ( P < 0.01). However, the total amount of released lactate and intracellular lactate was lower in the pressurized cells than in nonpressurized cells. These findings demonstrate that a pure pressure stimulus enhances aerobic metabolism in L6 skeletal muscle cells and raise the possibility that elevated intramuscular pressure during muscle activity may be an important factor in stimulating oxidative metabolic responses in skeletal muscles.

The behavior of inclined covers used as oxygen barriers

Covers with capillary barrier effects (CCBE) have been recently proposed as a viable option for gas migration barriers. However, the effect of geometry on CCBE performance has not been clearly demonstrated. In this paper, the results of a laboratory study performed with an original apparatus called the inclined box are presented. The results obtained show that the hydraulic behavior of layered covers is influenced by the inclination of the slope. Generally, the upper part of the slope contains less water than the lower part. This means that the upper part is less efficient than the lower part for limiting gas migration. The authors have also studied an existing site where a CCBE was built on a sloping surface. After validation of the numerical model with in situ measured data, the model was used to perform a parametric study to quantify the influence of the main CCBE parameters on its performance. The results obtained confirm those measured in the lab and clearly show how geometry influences the performance of the CCBE. Based on these results, a simple relationship is proposed for a preliminary estimation of sloping covers performance to limit oxygen migration by diffusion.Key words: cover with capillary barrier effects, acid mine drainage, slope effects, laboratory investigation, in situ measurements, design criteria.

2G Alters the Utricular Macula of Chick Embryos

Chick embryos (Gallus domesticus) exposed continuously from day one until 18 days of incubation to a 2G acceleration (hyperG chicks) force hatched with altered macular epithelia. Fertile eggs were placed in an incubator and exposed to 2G on a centrifuge by the original apparatus until 18 days of incubation. Effective 2G loads were obtained by rotating the apparatus at a constant velocity of 327.5 degree/sec with the incubator mounted at 55 cm from the center axis [1]. The vestibules of the newly hatch chicks were dissected and fixed in 2.5% glutaraldehyde. The utricles were rinsed in phosphate buffer, postfixed with 2% osmic acid and dehydrated in graded ethanol and embedded in plastic. Semithin sections were examined under Light microscopy with computerized video imaging system [2] and ultrathin sections were examined under TEM.