Preliminary evaluation of conceptual mechanical designs

Computational Design has traditionally required a great deal of geometrical and parametric data. This data can only be supplied at stages later than conceptual design, typically the detail stage, and design quality is given by some absolute fitness function. On the other hand, design evaluation offers a relative measure of design quality that requires only a sparse representation. Quality, in this case, is a measure of how well a design will complete its task.

The research intends to address the question: "Is it possible to evaluate a mechanical design at the conceptual design phase and be able to make some prediction of its quality?" Quality can be interpreted as success in the marketplace, success in performing the required task, or some other user requirement. This work aims to determine a minimum level of representation such that conceptual designs can be usefully evaluated without needing to capture detailed geometry. This representation will form the model for the conceptual designs that are being considered for evaluation. The method to be developed will be a case-based evaluation system, that uses a database of previous designs to support design exploration. The method will not be able to support novel design as case-based design implies the model topology must be fixed.

Effects of addiction-associated and affective stimuli on the attentional blink in a sample of abstinent opiate dependent patients

The attentional blink reveals the limits of the brain's ability in information processing. It has been extensively studied in people with neurological and psychiatric disturbances to explore the temporal characteristics of information processing and exami

Effects of unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm on synaptic plasticity in the hippocampal CA1 area in vivo

Repeated vivid recalls or flashbacks of traumatic memories and memory deficits are the cardinal features of post-traumatic stress disorder (PTSD). The underlying mechanisms are not fully understood yet. Here, we examined the effects of very strong fear conditioning (20 pairings of a light with a 1.5-mA, 0.5-s foot shock) and subsequent reexposure to the conditioning context (chamber A), a similar context (chamber B), and/or to the fear conditioned stimulus (CS) (a light) on synaptic plasticity in the hippocampal CA1 area in anesthetized Sprague-Dawley rats. The conditioning procedure resulted in very strong conditioned fear, as reflected by high levels of persistent freezing, to both the contexts and to the CS, 24 h after fear conditioning. The induction of long-term potentiation ON was blocked immediately after fear conditioning. It was still markedly impaired 24 h after fear conditioning; reexposure to the conditioning chamber A (CA) or to a similar chamber 13 (CB) did not affect the impairment. However, presentation of the CS in the CA exacerbated the impairment of LTP, whereas the CS presentation in a CB ameliorated the impairment so that LTP induction did not differ from that of control groups. The induction of long-term depression (LTD) was facilitated immediately, but not 24 h, after fear conditioning. Only reexposure to the CS in the CA, but not reexposure to either chamber A or B alone, or the CS in chamber B, 24 h after conditioning, reinstated the facilitation of LTD induction. These data demonstrate that unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm can have profound effects on hippocampal synaptic plasticity, which may aid to understand the mechanisms underlying impairments of hippocampus-dependent memory by stress or in PTSD. (c) 2005 Wiley-Liss, Inc.