Design and development of a one-degree-of-freedom force-reflecting manual controller prototype for teleoperation

The present research is carried out from the viewpoint of primarily space applications where human lives may be in danger if they are to work under these conditions. This work proposes to develop a one-degree-of-freedom (1-DOF) force-reflecting manual controller (FRMC) prototype for teleoperation, and address the effects of time delays commonly found in space applications where the control is accomplished via the earth-based control stations. To test the FRMC, a mobile robot (PPRK) and a slider-bar were developed and integrated to the 1-DOF FRMC. The software developed in Visual Basic is able to telecontrol any platform that uses an SV203 controller through the internet and it allows the remote system to send feedback information which may be in the form of visual or force signals. Time delay experiments were conducted on the platform and the effects of time delay on the FRMC system operation have been studied and delineated.

Principal component and second generation wavelet analysis of Treasury yield curve evolution

Prices of U.S. Treasury securities vary over time and across maturities. When the market in Treasurys is sufficiently complete and frictionless, these prices may be modeled by a function time and maturity. A cross-section of this function for time held fixed is called the yield curve; the aggregate of these sections is the evolution of the yield curve. This dissertation studies aspects of this evolution. ^ There are two complementary approaches to the study of yield curve evolution here. The first is principal components analysis; the second is wavelet analysis. In both approaches both the time and maturity variables are discretized. In principal components analysis the vectors of yield curve shifts are viewed as observations of a multivariate normal distribution. The resulting covariance matrix is diagonalized; the resulting eigenvalues and eigenvectors (the principal components) are used to draw inferences about the yield curve evolution. ^ In wavelet analysis, the vectors of shifts are resolved into hierarchies of localized fundamental shifts (wavelets) that leave specified global properties invariant (average change and duration change). The hierarchies relate to the degree of localization with movements restricted to a single maturity at the base and general movements at the apex. Second generation wavelet techniques allow better adaptation of the model to economic observables. Statistically, the wavelet approach is inherently nonparametric while the wavelets themselves are better adapted to describing a complete market. ^ Principal components analysis provides information on the dimension of the yield curve process. While there is no clear demarkation between operative factors and noise, the top six principal components pick up 99% of total interest rate variation 95% of the time. An economically justified basis of this process is hard to find; for example a simple linear model will not suffice for the first principal component and the shape of this component is nonstationary. ^ Wavelet analysis works more directly with yield curve observations than principal components analysis. In fact the complete process from bond data to multiresolution is presented, including the dedicated Perl programs and the details of the portfolio metrics and specially adapted wavelet construction. The result is more robust statistics which provide balance to the more fragile principal components analysis. ^

Differentiation of self and emerging adulthood

Today's young people are progressing from adolescence into adulthood differently than past generations, including taking a longer time to make this transition. Some believe that the developmental markers and tasks of this transitional period are unique enough to merit the designation of a new life stage--"emerging adulthood." Recently, this new life stage of emerging adulthood has received increasing attention in the developmental literature, including attention to the probable causes for its evolution. However, little is known about specific aspects of intra- and interpersonal development that occur during emerging adulthood. The purpose of this study was to empirically assess hypothesized relations between variables associated with the psychological constructs of attachment, psychosocial maturity, and differentiation of self, in a sample of emerging adults. Structural equation modeling (SEM) analyses indicated an association between the variables measuring these constructs (anxiety, avoidance, I-position, reactivity, cutoff, fusion, identity, and intimacy). The results from structural equation modeling (SEM) analyses helped to confirmed and extended previous research by demonstrating significant associations between attachment, psychosocial maturity, and differentiation of self through the variables operationalizing these constructs. Psychosocial maturity predicted differentiation of self (with intimacy predicting emotional cutoff and identity predicting cutoff and I-position). Attachment also predicted differentiation of self (with anxiety predicting all differentiation variables, and avoidance predicting emotional reactivity and cutoff). However, associations between anxiety and cutoff and between avoidance and cutoff were mediated by psychosocial identity and intimacy, and associations between anxiety and I-position were mediated by identity. Thus, these results corroborate and elaborate previous research conducted on these constructs. Specifically, relational tendencies thought to be influenced by attachment security impact interpersonal functioning in emerging adulthood, but this association is influenced by the degree of resolution of key psychosocial tasks.