Attitude dynamics simulation subroutines for systems of hinge-connected rigid bodies

Several computer subroutines are designed to provide the solution to minimum-dimension sets of discrete-coordinate equations of motion for systems consisting of an arbitrary number of hinge-connected rigid bodies assembled in a tree topology. In particular, these routines may be applied to: (1) the case of completely unrestricted hinge rotations, (2) the totally linearized case (all system rotations are small), and (3) the mixed, or partially linearized, case. The use of the programs in each case is demonstrated using a five-body spacecraft and attitude control system configuration. The ability of the subroutines to accommodate prescribed motions of system bodies is also demonstrated. Complete listings and user instructions are included for these routines (written in FORTRAN V) which are intended as multi- and general-purpose tools in the simulation of spacecraft and other complex electromechanical systems

Attitude dynamics simulation subroutines for systems of hinge-connected rigid bodies with nonrigid appendages

Three computer subroutines designed to solve the vector-dyadic differential equations of rotational motion for systems that may be idealized as a collection of hinge-connected rigid bodies assembled in a tree topology, with an optional flexible appendage attached to each body are reported. Deformations of the appendages are mathematically represented by modal coordinates and are assumed small. Within these constraints, the subroutines provide equation solutions for (1) the most general case of unrestricted hinge rotations, with appendage base bodies nominally rotating at a constant speed, (2) the case of unrestricted hinge rotations between rigid bodies, with the restriction that those rigid bodies carrying appendages are nominally nonspinning, and (3) the case of small hinge rotations and nominally nonrotating appendages. Sample problems and their solutions are presented to illustrate the utility of the computer programs

Determination of Pile Driveability and Capacity From Penetration Tests, Volume I: Final Report

DTFH61-93-C-00047Research has been conducted on the potential improvement of dynamic wave equation analysis methodology using in-situ soil testing techniques. As a basis for this investigation, the literature was reviewed and a summary was compiled of efforts made to date on the development of models and associated parameters for pile driving analysis. Furthermore a data base was developed containing more than 150 cases of test piles with static load tests, dynamic restrike tests, soil information, driving system data and installation records. One hundred data base cases were subjected to correlation studies using both wave equation and CAPWAP. This work yielded dynamic soil model parameters which did not indicate a specific relationship with soil grain size. The in-situ soil testing device utilized was a Modified SPT which yielded data from both static and dynamic measurements. Either static uplift or torque tests yielded static ultimate shaft resistance, and uplift tests also indicated a shaft resistance quake. Static compressive tests on a special tip indicated ultimate end bearing and associated toe quake. Indirectly, by signal matching, soil damping parameters were calculated. These quantities were then used for the prediction of full-scale pile behavior. Data from the Modified SPT were gathered and analyzed on six sites with previous full-scale static pile tests and on three sites where static load tests were to be performed at a later date. Recommendations derived from these tests pertain to the current soil model and to proposals for future changes. In general, the current approach was found to yield, on the average, very reasonable results for end of installation situations. For restrike tests, standard parameters may be misleading. Any necessary modifications to the current approach, for example, the use of particularly large toe quakes or low toe damping factors, should be based on Modified SPT measurements. Differences between prediction and full-scale pile field behavior were attributed to soil strength changes over relatively small distances which cannot be detected with standard SPT spacings of 5 ft (1.5 m)

Determination of Pile Driveability and Capacity From Penetration Tests, Volume II: Appendixes

DTFH61-93-C-00047Research has been conducted on the potential improvement of dynamic wave equation analysis methodology using in-situ soil testing techniques. As a basis for this investigation, the literature was reviewed and a summary was compiled of efforts made to date on the development of models and associated parameters for pile driving analysis. Furthermore a data base was developed containing more than 150 cases of test piles with static load tests, dynamic restrike tests, soil information, driving system data and installation records. One hundred data base cases were subjected to correlation studies using both wave equation and CAPWAP. This work yielded dynamic soil model parameters which did not indicate a specific relationship with soil grain size. The in-situ soil testing device utilized was a Modified SPT which yielded data from both static and dynamic measurements. Either static uplift or torque tests yielded static ultimate shaft resistance, and uplift tests also indicated a shaft resistance quake. Static compressive tests on a special tip indicated ultimate end bearing and associated toe quake. Indirectly, by signal matching, soil damping parameters were calculated. These quantities were then used for the prediction of full-scale pile behavior. Data from the Modified SPT were gathered and analyzed on six sites with previous full-scale static pile tests and on three sites where static load tests were to be performed at a later date. Recommendations derived from these tests pertain to the current soil model and to proposals for future changes. In general, the current approach was found to yield, on the average, very reasonable results for end of installation situations. For restrike tests, standard parameters may be misleading. Any necessary modifications to the current approach, for example, the use of particularly large toe quakes or low toe damping factors, should be based on Modified SPT measurements. Differences between prediction and full-scale pile field behavior were attributed to soil strength changes over relatively small distances which cannot be detected with standard SPT spacings of 5 ft (1.5 m)

Determination of Pile Driveability and Capacity from Penetration Tests, Volume III: Literature Review, Data Base and Appendixes

DTFH61-93-C-00047Research has been conducted on the potential improvement of dynamic wave equation analysis methodology using in-situ soil testing techniques. As a basis for this investigation, the literature was reviewed and a summary was compiled of efforts made to date on the development of models and associated parameters for pile driving analysis. Furthermore a data base was developed containing more than 150 cases of test piles with static load tests, dynamic restrike tests, soil information, driving system data and installation records. One hundred data base cases were subjected to correlation studies using both wave equation and CAPWAP. This work yielded dynamic soil model parameters which did not indicate a specific relationship with soil grain size. The in-situ soil testing device utilized was a Modified SPT which yielded data from both static and dynamic measurements. Either static uplift or torque tests yielded static ultimate shaft resistance, and uplift tests also indicated a shaft resistance quake. Static compressive tests on a special tip indicated ultimate end bearing and associated toe quake. Indirectly, by signal matching, soil damping parameters were calculated. These quantities were then used for the prediction of full-scale pile behavior. Data from the Modified SPT were gathered and analyzed on six sites with previous full-scale static pile tests and on three sites where static load tests were to be performed at a later date. Recommendations derived from these tests pertain to the current soil model and to proposals for future changes. In general, the current approach was found to yield, on the average, very reasonable results for end of installation situations. For restrike tests, standard parameters may be misleading. Any necessary modifications to the current approach, for example, the use of particularly large toe quakes or low toe damping factors, should be based on Modified SPT measurements. Differences between prediction and full-scale pile field behavior were attributed to soil strength changes over relatively small distances which cannot be detected with standard SPT spacings of 5 ft (1.5 m)

Long-term age-dependent behavioral changes following a single episode of fetal N-methyl-D-Aspartate (NMDA) receptor blockade

BACKGROUND: Administration of the N-methyl-D-aspartate (NMDA) antagonist ketamine during the perinatal period can produce a variety of behavioral and neuroanatomical changes. Our laboratory has reported reliable changes in learning and memory following a single dose of ketamine administered late in gestation. However, the nature of the drug-induced changes depends on the point during embryonic development when ketamine is administered. Embryonic day 18 (E18) rat fetuses pre-treated with ketamine (100 mg/kg, i.p. through the maternal circulation) and taught a conditioned taste aversion (CTA) learn and remember the CTA, whereas E19 fetuses do not. The current study sought to determine if long-term behavioral effects could be detected in animals that received ketamine or a saline control injection on either E18 or E19. Rat behavior was evaluated on two different measures: spontaneous locomotion and water maze learning. Measurements were collected during 2 periods: Juvenile test period [pre-pubertal locomotor test: Postnatal Day 11 (P11); pre-pubertal water maze test: P18] or Young-adult test period [post-pubertal locomotor test: P60; post-pubertal water maze test: P81]. RESULTS: Water maze performance of ketamine-treated rats was similar to that of controls when tested on P18. Likewise, the age of the animal at the time of ketamine/saline treatment did not influence learning of the maze. However, the young-adult water maze test (P81) revealed reliable benefits of prenatal ketamine exposure – especially during the initial re-training trial. On the first trial of the young adult test, rats treated with ketamine on E18 reached the hidden platform faster than any other group – including rats treated with ketamine on E19. Swim speeds of experimental and control rats were not significantly different. Spontaneous horizontal locomotion measured during juvenile testing indicated that ketamine-treated rats were less active than controls. However, later in development, rats treated with ketamine on E18 were more active than rats that received the drug on E19. CONCLUSION: These data suggest that both the day in fetal development when ketamine is administered and the timing of post-natal behavioral testing interact to influence behavioral outcomes. The data also indicate that the paradoxical age-dependent effects of early ketamine treatment on learning, previously described in fetuses and neonates, may also be detected later in young adult rats

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