Kinematic error modeling and analysis of the loading device based on multi-body theory and stream of variation theory
Because of some reasons such as machining error and assembly clearance, the loading device will produce kinematic error during movement. While kinematic error will have a great significance on the position accuracy of the loading device. For the above reasons, firstly, the topological structure of the loading device was described based on lower body arrays. The kinematic error matrices of adjacent parts in the loading device were obtained by multi-body system kinematic theory and homogeneous translation matrix (HTM). Then an improved error modeling method was put forward, which combined multi-body system theory with stream of variation theory. And the kinematic error model of the loading device was set up with this method. Numerical results could clearly display the error transformation and propagation among components. Finally, the effect of every kinematic error on final deviation was analyzed, and error sources of a greater effect on the final deviation were obtained. This method can provide a theoretical basis to improve the accuracy of the loading device.
Dynamics of multi-body systems
The dynamic equations of multi-body systems in the form of open chains are derived by applying the principles of linear and angular momenturn to each individual member in the chain. This results in the appearance of constraint forces and torques in the dynamic equations. Using more or less classical approach these unknown forces and torques can be eliminated. Another approach is to approximate these forces byelastic and viscous forces by allowing small violations of the constraints. The well-known elimination procedure leads to a small densely coupled system of equations while the lesser-known procedure of approximating the constraint forces and torques yields a large but less densely coupled system. Both these procedures are first explained in the context of a single rigid body and then applied to a system of rigid bodies in an open chain where each body is coupled directly to at most two neighbours.
Efficacy for Dealing With Terrorism Precautionary Behavior: Laying the Groundwork for Communication Effectiveness
In order to formulate effective communication and intervention strategies to respond to the widespread lack of preparedness for public health crises resulting from natural and human-made disasters, researchers have developed models describing the interrelationships between factors associated with emergency preparedness decisions. Empirical research has generally assumed that two key elements of most health behavior theories—self-efficacy and response efficacy—additively influence the decision to prepare, despite compelling theoretical rationale for an interactive relationship. The few studies that have investigated interactions in preparedness outcomes have not tested the Social Cognitive Theory prediction that non-zero levels of both efficacy types are required before individuals will engage in any preparedness behavior. Based on the responses of 3,101 participants in the National Survey of Disaster Experiences and Preparedness, this study tested additive, interactive, and conditional main effect hypotheses about the influence of self-efficacy and response efficacy for dealing with terrorism on preparedness due to terrorism six years after the September 11, 2001, terrorist attacks. A significant self-efficacy × response efficacy interaction effect on preparedness was found, in addition to a significant response efficacy effect when perceived self-efficacy was zero, contrary to the expectation from Social Cognitive Theory. These results offer insights into the cognitive processes underlying individuals’ decisions to prepare for disasters such as terrorist attacks, and highlight the importance of considering more complex theory-based cognitive interaction models in designing effective communication strategies to facilitate individual emergency preparedness.