The vibration characteristics of the door panels are affected by the weatherstrip seals used in between the doors and vehicle body along the perimeter of the doors. The weatherstrip seals exhibit ...nonlinear and viscoelastic material properties that vary with frequency, temperature, strain rate and amplitude, and previous load history. The material properties of the seal must be investigated carefully in order to predict the vibration characteristics of the automobiles under different loading conditions.
In this study, we developed hyperelastic and viscoelastic models of the weatherstrip seal to predict dynamic performance of a vehicle door and its effect on the overall vehicle dynamics. For this purpose, first, static compression and stress relaxation experiments were performed on the seal using a robotic indenter equipped with force and displacement sensors and then a finite element model utilising the results of these experiments was developed in ANSYS. Finally, a representative model of the seal was integrated into the finite element model of the vehicle door to investigate its effect on the vehicle vibrations. The model predictions were validated using experimental modal analysis performed on the vehicle door with and without the seal. It was observed that the seal has a significant effect on the vehicle dynamics.
Basdogan and Dikmen develop a methodology to characterize the viscoelastic coefficients of the weatherstrip seal using experimental methods and curve fitting techniques. They conduct stress ...relaxation experiments using a robotic indenter equipped with force and displacement sensors to characterize the viscoelastic behavior of the seal. A curve-fitting algorithm is developed in MATLAB (The Math Works, Natick, MA) that fits the experimental force relaxation response of the seal to a "ramp and hold" input using the generalized Maxwell solid. The fitting algorithm estimates the viscoelastic material coefficients of the system. These viscoelastic coefficients were substituted into the Maxwell solid model to estimate the frequency response function (FRF) of the seal. Independent of this approach, an impact test was also performed on the same seal to measure its FRF directly. They compare the FRF obtained from the impact test with the one obtained through the stress relaxation experiments and the discuss the results.
A procedure for calculating microscopically the input for standard shell-model calculations, i.e., the core and single-particle energies plus the two-body effective model-space interactions, is ...presented and applied to nuclei at the start of the sd-shell. Calculations with the JISP16 and Idaho χEFT N3LO nucleon-nucleon interactions are performed and yield consistent results, which also are similar to phenomenological results in the sd-shell as well as with other theoretical calculations, utilizing other techniques. All results show only a weak A-dependence.
In this study, time dependence of large-scale nuclear shell model calculations in a parallel cluster is investigated. Shell model calculations have been done for the light Sb isotopes by using serial ...and parallel versions of Drexel University Shell Model (DUSM) code and the time dependence of these calculations are obtained on the local Cyborg Parallel Cluster at Drexel University. Some analyses about what kind of parallel system we need to do the calculations have been done in order to do the nuclear shell model calculations for the other nuclei.
Effective interactions in the sd shell Smirnova, N. A.; Barrett, B. R.; Kim, Y. ...
Physical review. C,
11/2019, Letnik:
100, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We perform here a quantitative study of the microscopic effective shell-model interactions in the valence sd shell, obtained from modern nucleon-nucleon potentials, chiral N3LO, JISP16 and Daejeon16, ...using No-Core Shell-Model wave functions and the Okubo-Lee-Suzuki transformation. We investigate the monopole properties of those interactions in comparison with the phenomenological universal sd-shell interaction, USDB. Theoretical binding energies and low-energy spectra of O isotopes and of selected sd-shell nuclei, are presented. We conclude that there is a noticeable improvement in the quality of the effective interaction when it is derived from the Daejeon16 potential. We show that its proton-neutron centroids are consistent with those from USDB. We then propose monopole modifications of the Daejeon16 centroids in order to provide an adjusted interaction yielding significantly improved agreement with the experiment. A spin-tensor decomposition of two-body effective interactions is applied in order to extract more information on the structure of the centroids and to understand the reason for deficiencies arising from our current theoretical approximations. The concern of the possible role of the three-nucleon forces is addressed.
The ammonia-water mixture may be commonly employed as a working fluid in the absorption chiller, especially because both ammonia and water are natural substances and are harmless. In addition, these ...substances have excellent thermodynamic properties. In this study, an alternative method using the artificial neural network (ANN) to determine liquid and vapor enthalpies of ammonia-water mixture is presented. The training and validation was performed with good accuracy. The correlation coefficient obtained when unknown data were used to the networks was 0.975 for the liquid enthalpy and 0.887 for the vapor enthalpy. Using the weights obtained from the trained network, a new formulation is presented for the determination of the vapor and liquid enthalpies of ammonia-water mixture. The results of the study show that the ANN is a perfect alternative method for the calculation of thermodynamic properties of ammonia-water mixture. The faster and simpler solutions with equations derived from the ANN can be carried out.
The aim of the present study was to investigate the diagnostic efficacy of telomerase activity for discrimination of malignant and benign pleural effusions. Pleural effusions were collected from 109 ...consecutive patients in whom the diagnosis was confirmed with cytological and/or histological examinations. Cytological samples were classified as malignant (n=63) and benign (n=46). Telomerase activity was determined with the polymerase chain reaction-based telomeric repeat amplification protocol assay. Telomerase activity was detected in 52 (82.5%) and nine (19.6%) samples from the malignant and benign groups, respectively, which was a significant difference. The sensitivity rate of cytological examination when combined with telomerase activity (92.1%) was significantly greater than that of cytological examination alone (53.9%). The sensitivity and specificity of telomerase activity were 82.5 and 80.4%, respectively. Diagnostic accuracy of telomerase activity was 81.6%. Telomerase activity is a highly sensitive diagnostic biomarker for malignancy and may be used as an adjunct to cytological findings in determining malignant pleural effusions.
Human hepatocyte growth factor (hHGF) is the most potent mitogen identified for alveolar type II cells, and may have other important functions in the repair of the alveolar epithelium and ...compensatory lung growth. A study was conducted to evaluate the changes of serum hHGF levels in patients who underwent thoracic surgical procedures. The patients comprised 17 males and 14 females with a mean age of 47.1+/-13.5 yrs, who underwent either lung resection (LR group) or nonlung resection (nonLR group) thoracic procedures. The changes of hHGF levels were analysed in the pre- and post-operative periods in both groups. The pre-operative hHGF levels did not differ between the LR and the nonLR groups, which were 333.2+/-72.9 pg x mL(-1) and 343.6+/-125.3 pg x mL(-1), respectively. The hHGF levels in the LR group significantly increased up to 433.6+/-128.1 pg x mL(-1) and 430.8+/-128.2 pg x mL(-1) in post-operative days 1 and 3, respectively. However, the same levels in the nonLR group appeared as 333.2+/-77.0 pg x mL(-1) and 311.9+/-73.0 pg x mL(-1), respectively. In conclusion, the increases of serum human hepatocyte growth factor levels following pulmonary resection may imply the important role of human hepatocyte growth factor in lung regeneration or compensatory lung growth in humans.
Effective Interactions from No Core Shell Model Dikmen, E; Lisetskiy, A F; Barrett, B R ...
AIP conference proceedings,
11/2008, Letnik:
1072, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
We construct the many-body effective Hamiltonian for pf-shell by carrying out 2O. NCSM calculations at the 2-body cluster level. We demonstrate how the effective Hamiltonian derived from realistic ...nucleon-nucleon (NN) potentials for the 2O NCSM space should be modified to properly account for the many-body correlations produced by truncating to the major pf-shell. We obtain two-body effective interactions for the pf-shell by using direct projection and use them to reproduce the results of large scale NCSM for other light Ca isotopes.
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