Doctor of Philosophy

dissertationShape Memory Alloy (SMA) actuators are compact and have high force-to-weight ratios, making them strong candidates to actuate robots, exoskeletons, and prosthetics. However, these actuators are thermomechanical in nature and slow cooling rates can limit their performance. Electricity can resistively heat the SMA actuators very quickly to produce contraction. To improve the convective cooling, SMA wires have been embedded in vascular networks, allowing cold fluid to pass across the actuators and extend them faster. The vascular network can also deliver hot fluid to heat and contract the wire. To minimize the weight and size of the control hardware for the vascular and electrical networks, a scalable NxN architecture has been implemented that allows for 2N control devices to be shared amongst N2 actuators. This Network Array Architecture (NAA) allows each actuator to be controlled individually or in discrete subarrays. However, this architecture does not allow all combinations of actuators to be activated simultaneously; therefore a sequence of control commands may be required to achieve the complete desired actuation. This dissertation presents the development of an intelligent controller for large arrays of wet SMA actuators with electric and thermofluidic inputs. The controller uses graph theory to identify a sequence to control commands to optimize the performance of the actuators. By treating each actuator as binary (contracted / extended), the collected states of an actuator array can be represented as nodes of the graph and the discrete NAA control commands as the graph edges. By weighting the costs of the graph edges (actuation times, energy), graph theory algorithms can find a set of control commands to transition the array to the desired state with specific performance characteristics. NAA results in a multi-graph that has a large number of nodes (2NxN) and is highly interconnected, causing problems with scalability. The search algorithm has incorporated an expanding wavefront algorithm to construct only a small portion of the graph as needed. The computational cost to construct the graph has been minimized by using bitwise operations and the discrete nature of the array of binary actuators and the NAA control commands. The algorithm was implemented in MATLAB and it is able to identify the optimal solution for a 4x4 array with more than 14 million edges. By using an expanding wavefront, the algorithm, on average, explored less than 100 edges (<0.01%) in 0.03 seconds. A 6x6 array was optimized in 0.7 seconds, exploring just 2400 edges

Microneedle assisted percutaneous delivery of lidocaine carboxymethylcellulose with gelatine co-polymer hydrogel

Local anaesthetic drugs are usually administered as symptom relieving drug formulations for the treatment of pain in superficial skin extremities. The anaesthesia is delivered into skin tissues at the site of pain because of nociceptive receptors. Concerns that exist regarding local anaesthetic drug formulations are low drug encapsulation efficiency, polydispersity of colloidal formulations, chemical interactions of released local anaesthetic drug with skin proteins and bulk viscoelastic properties. Complimenting drug formulation characteristics are the desirable rates of controlled release of drug molecules from chosen formulations pertaining to favourable in vitro skin permeation kinetics are imperative pharmaceutics based research areas because skin percutaneous delivery has distinct barrier property restrictions for passive diffusion (PD) of active molecules. Lidocaine is currently the active anaesthetic molecule of choice in local anaesthesia by clinicians because of minimum toxicity and good potency. It is a low molecular weight drug comprising of electron donating and electron withdrawing functional groups with the capacity to interact by hydrogen bonding and electrostatic interactions with several drug formulation vehicles. In this work, a naturally occurring bi-polymeric formulation was achieved with lidocaine NaCMC:gelatine hydrogel. Lidocaine NaCMC:gelatine ratio of 1:2.3 was the most favourable formulation because of faster skin permeation kinetics. Lidocaine NaCMC:gelatine 1:2.7 provided the highest drug encapsulation efficiency. This resulted in high, sustained permeation rates after adaptation of the microneedle (MN) poke and patch technique, past the stratum corneum layer of skin for quick target delivery in attaining a maximum permeation flux of near 6.0 µg/cm2/h in the hypodermis layer. Mass balance of in vitro studies using an indirect approach to quantify lidocaine permeation showed significant lidocaine permeation in skin. Subsequent vertical and horizontal (depth averaged) in vitro studies using similar MN techniques resulted in crossing minimum therapeutic level across a 10 mm radius from the epicentre of the skin sample at major reduced lag times of minutes for vertical permeation and within 0.5 hours for horizontal permeation. Furthermore, the spreadability of lidocaine NaCMC:gelatine hydrogel shows favourability in the control of droplet spreading on MN treated skin

Faculty Publications and Creative Works 2004

Faculty Publications & Creative Works is an annual compendium of scholarly and creative activities of University of New Mexico faculty during the noted calendar year. Published by the Office of the Vice President for Research and Economic Development, it serves to illustrate the robust and active intellectual pursuits conducted by the faculty in support of teaching and research at UNM

Acoustic Waves

The concept of acoustic wave is a pervasive one, which emerges in any type of medium, from solids to plasmas, at length and time scales ranging from sub-micrometric layers in microdevices to seismic waves in the Sun's interior. This book presents several aspects of the active research ongoing in this field. Theoretical efforts are leading to a deeper understanding of phenomena, also in complicated environments like the solar surface boundary. Acoustic waves are a flexible probe to investigate the properties of very different systems, from thin inorganic layers to ripening cheese to biological systems. Acoustic waves are also a tool to manipulate matter, from the delicate evaporation of biomolecules to be analysed, to the phase transitions induced by intense shock waves. And a whole class of widespread microdevices, including filters and sensors, is based on the behaviour of acoustic waves propagating in thin layers. The search for better performances is driving to new materials for these devices, and to more refined tools for their analysis

Human reproduction in space. Late results

Objectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag

Life Sciences Program Tasks and Bibliography for FY 1996

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1996. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web page

Schweizerische Präsenz an internationalen Forschungsfronten 1999

Winterhager M, Schwechheimer H. Schweizerische Präsenz an internationalen Forschungsfronten 1999. Center for Science and Technology Studies. Vol 2002,8. Bern: CEST; 2002.Ziel der vorliegenden Untersuchung ist die Identifikation und Analyse der wichtigsten Forschungsfronten, an denen in der Schweiz tätige Forschende 1999 beteiligt waren. Schwerpunkte schweizerischer Forschungsaktivität werden durch ein bibliometrisches Profil auf der Grundlage einer Ko-Zitationsanalyse transparent gemacht. Die mit der Ko-Zitationsanalyse identifizierten Forschungsfronten liefern eine Abbildung der aktuellen Forschungslandschaft, die allein auf der Auswertung der Ströme formaler Kommunikation (Publikationen und Zitationen) beruht. In diesem Sinne ist das Verfahren unabhängig von bestehenden Klassifikationsschemata, disziplinären Zuordnungen und subjektiven Sichtweisen einzelner Experten. Es nutzt lediglich die durch die publizierenden Forscherinnen und Forscher selbst realisierten kognitiven Bezüge, um aktuelle Forschungsfronten zu identifizieren und ihre Relationen zueinander darzustellen. Der Bericht dokumentiert zunächst das Ergebnis der Suche nach den Forschungsfronten mit schweizerischer Beteiligung. Als Datenbasis wurde eine Ko-Zitationsanalyse des Jahrgangs 1999 des Science Citation Index Expanded und des Social Sciences Citation Index herangezogen. Diese Datenbasis besteht aus insgesamt 22942 Forschungsfronten aus allen disziplinären Bereichen. Die Forschungsfronten werden ohne vorgängige disziplinäre Kategorisierungen generiert und sind daher in besonderer Weise geeignet, interdisziplinäre Entwicklungen abzubilden. Aus dem Gesamtdatenbestand aller Fronten des Jahrgangs 1999 wurden diejenigen 2.404 ausgewählt, in deren Kern mindestens eine Publikation schweizerischen Ursprungs enthalten ist