Possibilities of measuring the local density of seawater in probe instruments

In modern expeditionary research carried out on research vessels, the local density of seawater is not measured, but calculated using the TEOS-10 thermodynamic equation of state based on cumulative measurements of pressure, temperature and electrical conductivity or speed of sound. The equation of state with satisfactory accuracy is valid only for oceanological waters, and is used with corrections for the waters of the marginal and inland seas. These corrections are permanently refined and will be refined in the future. It is desirable to have direct measurements of the local density of any waters directly in the environment with sufficient accuracy, which is now 4·10-6. Laboratory measurements made by various methods and with different devices, not always automated, give accuracy ~ . Attempts to automate these measurements and introduce them into sounding devices have been made several times. Experimental samples of vibration, refractometric and hydrostatic devices have been created and tested, none of which have been introduced into the practice of expeditionary work for various reasons. However, scientific and technological progress makes possible technical solutions previously difficult to implement. This also applies to modifications of the hydrostatic method for measuring the local density, which have recently attracted the interest of developers. The paper analyzes the possibilities of implementing the hydrostatic method using multi-element resistor distributed pressure and temperature sensors, resistance profilers of these sensors and determining the spatial pressure drop on a given base by measuring and subtracting sensor resistances, taking into account temperature correction. The use of three such sensors, mounted on three rods, oriented downward along the axes of a rectangular coordinate system, provides the possibility of measuring the local density with an arbitrary orientation of the probe relative to the vertical. The analysis shows the possibility of measuring the local density of seawater by the hydrostatic method with the required accuracy in probe instruments.

Estimation of Chemical Composition of Pork Trimmings by Use of Density Measurement—Hydrostatic Method

This study aims to determine the possibility of using density measurements by using the hydrostatic method for the estimation of the chemical composition of pork. The research material included 75 pork samples obtained during industrial butchering and cutting. The density measurements were performed using the hydrostatic method based on Archimedes’ principle. The meat samples were minced, and the content of the basic chemical components in them was determined. The usefulness of density measurement using the hydrostatic method in chemical composition estimation was determined by analyzing the correlation for the entire population, and after grouping the samples with a low (<15%), medium (15–25%), and high (>25%) fat content. High (in absolute value) coefficients of correlation between the meat density and the content of water (0.96), protein (0.94), and fat (−0.96) were found based on the results obtained. In order to achieve higher accuracy of the estimation, the applied regression equations should be adjusted to the presumed fat content in the meat. The standard error of prediction (SEP) values ranged from 0.67% to 2.82%, which indicates that the calculated estimation accuracy may be sufficient for proper planning of the production. Higher SEP values were found in fat content estimation and the lowest ones were found in protein content estimation.

Wear resistance of the diamond-impregnated specimens fabricated using the SPS process

This paper presents the tribological properties of the diamond-impregnated specimens in the grinding process of sandstone materials. Obtained metallic-diamond composites were homogenized in Speed Mixer and sintered by SPS (spark plasma sintering). The matrix was prepared from: Cu-Sn (NAM-40 80/20 containing 20% wt. Sn) and Fe-Cu-Sn powders. After consolidation the diamond-impregnated specimens were tested for density using the hydrostatic method, Rockwell’s hardness using B scale and for wear rate on abrasive sandstone using a testing rig specially designed to simulate the tool application conditions.

Investigation on Measurement Method of Weight Volume Based on Acoustics

The measurement value of weight volume is important for correcting buoyancy influence in the mass measurement. Traditional measurement method of weight volume is hydrostatic method. It is the most accurate method currently, but it is a complicated process requiring the weight to be wetted in a reference fluid. To eliminate the influence of liquid against weight mass in the determination of weight volume of the hydrostatic method, the measurement method of weight volume based on acoustics is introduced in the paper. The results from 1 kg to 20 kg show accuracy of the measurement system is enough to measuring volume of class E weight. The relative extend uncertainty of measurement method of weight volume based on acoustics is less than 8×10-4.