Inertia Moment Value Research Articles

Pump-stopping-induced hydraulic oscillations in long-distance district heating system: Modelling and a comprehensive analysis of critical factors

To achieve low-carbon goals, long-distance district heating (LDH) systems are widely applied, which utilize the waste heats from renewable energy power plants and waste incineration plants. The hydraulic oscillations induced by pump-stopping in LDH systems may give rise to critical incidents, such as pipeline ruptures and heating disruptions. The systematic analysis of hydraulic oscillations induced by pump-stopping and the subsequent revelation of critical factors that mitigate their intensity are fundamental prerequisites for ensuring the safety and reliability of LDH system. In this paper, firstly, a pump-stopping hydraulic transient model of the LDH system is established based on the distributed parameter method. Then, combining the method of characteristics (MOC) and the Newton iteration method, the numerical solution scheme for this model is proposed. Finally, taking a 20 km LDH system as an example, the characteristics of hydraulic oscillations induced by pump-stopping is analyzed, and the key factors influencing the intensity of these hydraulic oscillations are investigated. In addition, the differences between hydraulic oscillations induced by pump-stopping and those induced by sudden faults on pipelines are also analyzed. The results indicate that an optimal pump inertia moment value and a properly sized bypass pipe at the pump significantly mitigate hydraulic oscillations, while the influence of constant pressure at the heat source inlet on hydraulic oscillations can be negligible. Our study has important reference value for improving the safe and reliable operation of LDH systems.

Biomechanical properties of anuran long bones: correlations with locomotor modes and habitat use

Long bones are subjected to mechanical loads during locomotion that will influence their biomechanical properties through a feedback mechanism (the bone mechanostat). This mechanism adapts the spatial distribution of the mineralized tissue to resist compression, bending and torsion. Among vertebrates, anurans represent an excellent group to study long bone properties because they vary widely in locomotor modes and habitat use, which enforce different skeletal loadings. In this study, we hypothesized that (a) the cortical bone mass, density and design of anuran femur and tibiofibula would reflect the mechanical influences of the different locomotor modes and habitat use, and (b) the relationships between the architectural efficiency of cortical design (cross-sectional moments of inertia) and the intrinsic stiffness of cortical tissue [cortical mineral density; the 'distribution/quality' (d/q) relationship] would describe some inter-specific differences in the efficiency of the bone mechanostat to improve bone design under different mechanical loads. To test this hypothesis, we determined tomographic (peripheral quantitative computed tomography) indicators of bone mass, mineralization, and design along the femur and tibiofibula of four anuran species with different modes of locomotion and use of habitat. We found inter-specific differences in all measures between the distal and proximal ends and mid-diaphysis of the bones. In general, terrestrial-hopper species had the highest values. Arboreal-walker species had the lowest values for all variables except for cortical bone mineral density, which was lowest in aquatic-swimmer species. The d/q relationships showed similar responses of bone modeling as a function of cortical stiffness for aquatic and arboreal species, whereas terrestrial-hoppers had higher values for moments of inertia regardless of the tissue compliance to be deformed. These results provide new evidence regarding the significant role of movement and habitat use in addition to the biomechanical properties of long bones within a morpho-functional and comparative context in anuran species.

Effect of antibrowning agents on fresh-cut potato tubers using frequency filtering of biospeckle images

Our present work aims to study the physiological changes of chemically treated fresh-cut potato tubers and then to correlate such changes with the results of the non destructive and non invasive laser biospeckle technique. The effect of chemically treated (citric acid (CA-0.5% and 1.0%) and citric acid + sodium chloride (CS-0.5% and 1.0%)) fresh-cut potato tubers on physiological activities such as the respiration rate and weight loss at cold storage has been studied for eight consecutive days. In addition, biospeckle recording has been carried out for eight consecutive days for all the chemically treated samples and from captured images, and the numerical results (inertia moment (IM)) with and without frequency filtering have been obtained. A comparatively higher respiration rate and lower weight loss is observed for CS treated samples than that of CA treated samples. The results of the IM obtained with the exclusion of the higher frequency show a similar nature to the respiration rate and also, separations of the respiration curves at two concentrations for both the treated samples were well correlated with the IM curves. The concentration effect for both the treatments on the IM value with the exclusion of lower frequencies has also been presented. Thus the IM method with filtration of particular bands is able to separate the different physiological phenomena with one another and is also able to differentiate the chemical effect on the samples.

Experimental parameters estimation of satellite attitude control simulator

Placing a satellite or any other spacecraft in orbit is a risky and expensive process; years of research and a lot of money are transformed into equipments that will be beyond any possibility of maintenance in case something goes wrong. Therefore, space projects must be carried on as carefully as possible in order to guarantee that satellite equipments perform its mission properly. In that context, experimental validation of new equipment and/or control techniques through prototypes is the way to increase system confidence. The Space Mechanics and Control Division (DMC) of INPE is constructing a 1D simulator, with rotation around the vertical axis and a 3D simulator, with rotation in three axes, to implement and test satellite Attitude Control System (ACS). However, to perform experimental test it is necessary to estimate the platform inertia parameters in order to balance the platform accurately, so it behaves similar to space torque free conditions. This paper presents the equations of motion and control law design for a 3 D attitude control system simulator. This 3 D model is simplified to 1D simulator from which the inertia moment is estimated by a recursive least squares that uses experimental data. The platform data are obtained in a simple experiment where a reaction wheel is used to apply torques and a gyroscope is used to measure the platform angular velocity. The inertia moment estimated by this approach is very close to the platform inertia moment value obtained by other method.

Investigation of Conformationally Rich Molecules: Rotational Spectra of Fifteen Conformational Isomers of 1-Octene

The rotational spectra of 15 conformational isomers of 1-octene have been measured in a molecular beam at a rotational temperature of less than 2 K using a pulsed-nozzle Fourier transform microwave spectrometer. The transition assignments are guided by rotational constant calculations based on moderate-level ab initio theory and on the relative energy minima on the MM3 molecular-mechanics force field. The number of conformers identified is slightly more than 10% of the 131 predicted from the MM3 molecular-mechanics force field of Allinger et al. Fourteen of the observed conformers are identified with 14 of the 15 lowest energy minima predicted from the MM3 molecular-mechanics force field. The observation of such a large number of conformers, with a MM3 calculated energy spread of 365 cm-1 for this subset of 14, is a consequence of the minimal conformational cooling in the molecular-beam expansion. Limiting this cooling are the relatively high barriers separating the conformers compared to the thermal energy, kT, of the preexpansion gas. In some cases, primarily for the higher energy conformers, the need to cross multiple internal-rotation barriers provides an additional bottleneck for conformer relaxation. The rotational spectra furnish values for the principal moments of inertia, which are sensitive to the conformational geometry and can be compared with predictions from future high-level ab initio calculations. Assuming no conformer relaxation in the expansion allows the use of the transition-intensity data to estimate the energy ordering of the conformers.

Ideal gas thermodynamic properties of six chlorofluoromethanes

Spectroscopic and thermal data were reviewed. The selected values for the principal moments of inertia, the vibrational fundamentals, and the standard enthalpy of formation at 298.15 K for each of the six chlorofluoromethanes were used to derive the chemical thermodynamic properties of molecules from 0 to 1500 K, based on the rigid-rotor harmonic-oscillator approximation. The calculated values are in accord with experimental heat capacities and entropies.

Stabilization of Motion Trajectories of Servo Drive on Varying Parameters of Control Object Conditions

Practical approach designated for programmed trajectories of servo drive operating on varying parameters of transported object conditions stabilization is proposed and investigated in the paper. It is proposed in combination with MRSAC method, introduced in to speed control subsystem, to use means limiting derivative of position controller output signal. It is shown that in order to enlarge the permissible range of inertia moment variation the speed controller of speed regulation module should be adjusted under the maximum supposed inertia moment value The modelling results of the system are given. Ill. 5, bibl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.109.3.176

Fission-Excitation Functions in Interactions ofC12,O16, andNe22With Various Targets

The fission cross sections ${\ensuremath{\sigma}}_{f}$ in the bombardment of Cs, Pr, Tb, Ho, ${\mathrm{Er}}^{170}$, Tm, ${\mathrm{Yb}}^{174}$, Lu, ${\mathrm{W}}^{182}$, Au, and Bi with ${\mathrm{O}}^{16}$, Tm with ${\mathrm{C}}^{12}$, and Tb with ${\mathrm{Ne}}^{22}$ have been measured as a function of projectile energy. The technique consists of counting coincident fission-fragment pairs with two Au surface-barrier Si detectors. The results are given in units of the total interaction cross section ${\ensuremath{\sigma}}_{R}$, and as a function of the excitation energy $E$ of the compound nucleus. It is demonstrated that for a constant value of $E$ for a compound nucleus $\frac{{\ensuremath{\sigma}}_{f}}{{\ensuremath{\sigma}}_{R}}$ is a function of the mass of the ion used and thus of the angular momentum of the nucleus. Fission for the systems investigated takes place only for nuclei formed in a complete fusion of the ion and the target nuclei. The cross section of ${\ensuremath{\sigma}}_{\mathrm{CF}}$ for this process is shown to be nearly independent of $E$ and the target used. We find $\frac{{\ensuremath{\sigma}}_{\mathrm{CF}}}{{\ensuremath{\sigma}}_{R}}$ to be 0.70 and 0.45 for ${\mathrm{O}}^{16}$ and ${\mathrm{Ne}}^{22}$, respectively. From the ratio $\frac{{\ensuremath{\sigma}}_{f}}{{\ensuremath{\sigma}}_{\mathrm{CF}}}$, experimental $\frac{{\ensuremath{\Gamma}}_{f}}{{\ensuremath{\Gamma}}_{n}}$ values are obtained and compared to theoretical ones. The following values in MeV with a standard deviation of 2 MeV for the experimental fission threshold for a nonrotating nucleus are obtained: 34.9, 26.5, 25.1, 24.6, 24.2, 20.4, 19.8, 18.2, and 17.0 for the compound nuclei ${\mathrm{Eu}}^{149}$, ${\mathrm{Ho}}^{157}$, ${\mathrm{Ta}}^{175}$, ${\mathrm{Re}}^{181}$, ${\mathrm{Os}}^{186}$, ${\mathrm{Ir}}^{185}$, ${\mathrm{Pt}}^{190}$, ${\mathrm{Au}}^{191}$, and ${\mathrm{Po}}^{198}$, respectively. These values, when corrected for shell effects, fit well the formula for a nonrotating charged liquid drop: ${{E}_{f}}^{L}=6.76(0.75\ensuremath{-}x){A}^{\frac{2}{3}}$. Here, $x=\frac{(\frac{{Z}^{2}}{A})}{{(\frac{{Z}^{2}}{A})}_{\mathrm{crit}.}}$ and we obtain the value 48.0\ifmmode\pm\else\textpm\fi{}1.0 for ${(\frac{{Z}^{2}}{A})}_{\mathrm{crit}.}$. The ratio between the level-density parameters for fission and neutron evaporation $\frac{{a}_{f}}{{a}_{n}}$ is found to be 1.22\ifmmode\pm\else\textpm\fi{}0.05; this ratio is independent of nuclear type. In particular, the ratio is nearly the same inside and outside the region of the closed shell. Values for moments of inertia can not be evaluated from the analysis.

Infrared Spectra of CH2N2 and CD2N2

The infrared spectra of CH2N2 and CD2N2 have been investigated in the gas phase between 4500 and 400 cm−1 using a Perkin-Elmer spectrometer with LiF, NaCl, and KBr prisms. The spectra have been correlated with a planar, nonlinear configuration for the diazomethane molecule with symmetry C2v. The perpendicular type bands for both molecules are all overlapped or perturbed by neighboring absorption bands, so that no accurate values for the least moments of inertia have been obtained. Two alternative schemes of assignments for the vibrational frequencies have been proposed and the thermodynamic functions for CH2N2 computed. Potential-function calculations have been carried out.