scholarly journals Optimization of insulation layer location and distribution considering maximum time lag and damping factor

Author(s):  
Yihang Lu ◽  
Jun Hu ◽  
Ke Zhong
Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. S221-S231 ◽  
Author(s):  
B. Arntsen ◽  
A. Kritski ◽  
B. Ursin ◽  
L. Amundsen

The U/D imaging condition for shot profile migration can be used to estimate the angle dependent reflection coefficient, but is difficult to implement numerically because of the spectral division involved. Most techniques for stabilizing the division require a damping factor which might be difficult to estimate and which also introduces bias into the final result. A stable result can be achieved by approximating the imaging condition with a crosscorrelation of the up- and downgoing wavefields at zero time lag, but this will lead to incorrect amplitude-versus-angle (AVA) behavior of the estimated reflection coefficient. We use a simple model for wave propagation of primary reflections in the wavenumber frequency domain and invert the model with respect to the reflection coefficient. By using the properties of wavefield extrapolators it can then be shown that the reflection coefficients can be estimated by crosscorrelation of the upgoing wavefield and a downgoing wavefield where the initial wavefield is the inverse of the wavefield generated by a point source. The new imaging condition gives the correct AVA behavior for horizontal reflectors. For dipping reflectors it is shown that a postmigration correction factor can be used to recover the correct angle behavior of the reflection coefficient. The new imaging condition is numerically stable, does not involve damping factors, is simple to implement numerically, and is a simple modification of the classical crosscorrelation imaging condition. Numerical examples confirm the correct AVA behavior of the new imaging condition.


2019 ◽  
Vol 40 (3) ◽  
pp. 177-185
Author(s):  
Daniela Moza ◽  
Laurențiu Maricuțoiu ◽  
Alin Gavreliuc

Abstract. Previous research established that an independent construal of the self is associated with higher self-esteem, which, in turn, is associated with increased happiness. Regarding the directionality of these relationships, theoretical arguments have suggested that self-construal precedes self-esteem and that self-esteem precedes happiness. However, most research in this area is cross-sectional, thus limiting any conclusions about directionality. The present study tested these relationships in 101 Romanian undergraduates using a 3-wave cross-lagged design with a 6-month time lag between every two waves. Structural equation modeling analyses revealed that self-esteem is an antecedent of both happiness and dimensions of independent self-construal (i.e., consistency vs. variability and self-expression vs. harmony). In other words, one’s positive evaluation of self-worth precedes one’s self-perception as being a happy and independent person. The findings are discussed with respect to the theoretical and practical implications, along with limitations and suggestions for future research.


2014 ◽  
Vol 13 (2) ◽  
pp. 87-96 ◽  
Author(s):  
Xi-Chao Zhang ◽  
Oi Ling Siu ◽  
Jing Hu ◽  
Weiwei Zhang

This study investigated the direct, reversed, and reciprocal relationships between bidirectional work-family conflict/work-family facilitation and psychological well-being (PWB). We administered a three-wave questionnaire survey to 260 married Chinese employees using a time lag of one month. Cross-lagged structural equation modeling analysis was conducted and demonstrated that the direct model was better than the reversed causal or the reciprocal model. Specifically, work-to-family conflict at Time 1 negatively predicted PWB at Time 2, and work-to-family conflict at Time 2 negatively predicted PWB at Time 3; further, work-to-family facilitation at Time 1 positively predicted PWB at Time 2. In addition, family-to-work facilitation at Time 1 positively predicted PWB at Time 2, and family-to-work conflict at Time 2 negatively predicted PWB at Time 3.


2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S57-S57
Author(s):  
Ken-ichiro Kasura ◽  
Megumi Watanabe ◽  
Kumiko Takahashi ◽  
Genki Mizukoshi ◽  
Seiji Ohkubo ◽  
...  

1974 ◽  
Vol 32 (01) ◽  
pp. 057-064 ◽  
Author(s):  
Y Nemerson ◽  
S.A Silverberg ◽  
J Jesty

SummaryTwo reactions of the extrinsic pathway of coagulation, the activations of Factor X and prothrombin, have been studied in purified systems and shown to be self-damping. Factor X was activated by the tissue factor - Factor VII complex, and prothrombin by two systems: the coagulant protein of Taipan venom, and the physiological complex of activated Factor X, Factor V, lipid, and calcium ions. In each case the yield of enzyme, activated Factor X or thrombin, is a function of the concentration of activator. These and other observations are considered as a basis for a control mechanism in coagulation.


1978 ◽  
Vol 39 (02) ◽  
pp. 346-359 ◽  
Author(s):  
P D Winocour ◽  
M R Turner ◽  
T G Taylor ◽  
K A Munday

SummaryA major limitation to single-cell protein (SCP) as a human food is its high nucleic acid content, the purine moiety of which is metabolised to uric acid. Rats given a Fusarium mould as a source of SCP in diets containing oxonate, a uricase inhibitor, showed elevated plasma and kidney uric acid concentrations after 21 d, which were related to the level of dietary mould. ADP-induced and thrombin-induced platelet aggregation was greater in the hyperuricaemic rats than in controls and a progressive increase in aggregation with increasing levels of dietary mould was observed. Furthermore a time-lag, exceeding the life-span of rat platelets, was observed between the development of hyperuricaemia and the increase in aggregation. A similar time-lag was observed between the lowering of the hyperuricaemia and the reduction of platelet aggregation when oxonate was removed from the diet.If human platelets react to uric acid in the same manner as rat platelets this might explain the link that has been suggested between hyperuricaemia and ischaemic heart disease. In that event diets high in nucleic acids might be contra-indicated in people at risk from ischaemic heart disease.In rats given a low protein diet (50 g casein/kg) for 21 d ADP-induced and thrombin-induced platelet aggregation and whole blood platelet count were reduced compared with control animals receiving 200 g casein/kg diet but not in rats given 90 or 130 g casein/kg diet. A study of the time course on this effect indicated that the reduction both in aggregation tendency and in whole blood platelet count occurred after 4 d of feeding the low protein diet. These values were further reduced with time.


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