Design and integrity of deterministic system architectures.

Architectures represented by system construction 'building block' components and interrelationships provide the structural form. This thesis addresses processes, procedures and methods that support system design synthesis and specifically the determination of the integrity of candidate architectural structures. Particular emphasis is given to the structural representation of system architectures, their consistency and functional quantification. It is a design imperative that a hierarchically decomposed structure maintains compatibility and consistency between the functional and realisation solutions. Complex systems are normally simplified by the use of hierarchical decomposition so that lower level components are precisely defined and simpler than higher-level components. To enable such systems to be reconstructed from their components, the hierarchical construction must provide vertical intra-relationship consistency, horizontal interrelationship consistency, and inter-component functional consistency. Firstly, a modified process design model is proposed that incorporates the generic structural representation of system architectures. Secondly, a system architecture design knowledge domain is proposed that enables viewpoint evaluations to be aggregated into a coherent set of domains that are both necessary and sufficient to determine the integrity of system architectures. Thirdly, four methods of structural analysis are proposed to assure the integrity of the architecture. The first enables the structural compatibility between the 'building blocks' that provide the emergent functional properties and implementation solution properties to be determined. The second enables the compatibility of the functional causality structure and the implementation causality structure to be determined. The third method provides a graphical representation of architectural structures. The fourth method uses the graphical form of structural representation to provide a technique that enables quantitative estimation of performance estimates of emergent properties for large scale or complex architectural structures. These methods have been combined into a procedure of formal design. This is a design process that, if rigorously executed, meets the requirements for reconstructability

A Study Of The Penetration And Sharpness Of Surgical Blade

Sharpness of surgical blades is an important parameter in cutting human tissues and skins. It has a critical effect on the quality of cutting (scarring, pain, sharps injury and infection transmission issues), the required energy to do the cutting, the surgery operation time and the protection for medical officers. Presently, there is no standard or protocol available to quantify the blade penetration and sharpness. In this work, a customized cutting test machine is designed and developed for the purpose of measuring the cutting force of surgical blade

Transient analysis of deterministic and stochastic Petri nets with concurrent deterministic transitions

This paper introduces an efficient numerical algorithm for transient analysis of deterministic and stochastic Petri nets (DSPNs) and other discrete-event stochastic systems with exponential and deterministic events. The proposed approach is based on the analysis of a general state space Markov chain (GSSMC) whose state equations constitute a system of multidimensional Fredholm integral equations. Key contributions of this paper constitute the observations that the transition kernel of this system of Fredholm equations is piece-wise continuous and separable. Due to the exploitation of these properties, the GSSMC approach shows great promise for being effectively applicable for the transient analysis of large DSPNs with concurrent deterministic transitions. Moreover, for DSPNs without concurrent deterministic transitions the proposed GSSMC approach requires three orders of magnitude less computational effort than the previously known approach based on the method of supplementary variables

Probing the local activity of CO2 reduction on gold gas diffusion electrodes: effect of the catalyst loading and CO2 pressure

Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO2 reduction to CO. We have used shear-force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface-generation tip collection mode to evaluate the activity of Au GDEs for CO2 reduction as a function of catalyst loading and CO2 back pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO2 back pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO2 back pressure on their performance.Catalysis and Surface Chemistr

Probing the local activity of CO2 reduction on gold gas diffusion electrodes: effect of the catalyst loading and CO2 pressure

Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO2 reduction to CO. We have used shear-force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface-generation tip collection mode to evaluate the activity of Au GDEs for CO2 reduction as a function of catalyst loading and CO2 back-pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO2 back-pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO2 back-pressure on their performance.Horizon 2020(H2020)722614-ELCORELCatalysis and Surface Chemistr

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 376)

This bibliography lists 265 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Jun. 1993. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

Micropower Impulse Radio For Remote Controlled Insect Flight

Insects have remarkable strength and stamina compared to their body mass and fly and manuver effortlessly in ways that are impossible for present day robotic flyers. Therefore, efforts to control and direct flying insects for our own purposes have a huge potential payoff. One such effort, discussed in this dissertation, concerns the control of a Manduca Sexta moth by sending commands by radio to neural probes implanted in the thorax. The electronics hardware represents a major challenge in itself because the moth can carry only 700 milligrams, most of which is occupied by a small watch-battery. Ultimately, the moth must carry not only a radio receiver to pick up commands sent by the controller, but also a transmitter to return gathered information and fulfill its mission. Commercial "low-power", burst-mode radios have proven inadeqate because the battery cannot satisfy their peak power consumption. Instead, this dissertation focuses on the development of an alternative "impulse radio", which consumes power only during the ~100 picosecond interval required to generate a microwave pulse. The specific transmitter architecture presented here uses a nonlinear transmission line to directly convert digital signals provided by a microcontroller into microwave pulses broadcast by an antenna. This dissertation discusses (1) the background and theory of impulse-radios and (2) nonlinear transmission lines, (3) circuit board prototypes and (4) a CMOS implementation of the trans- mitter, (5) a study of the wireless link between the moth and its controller, as well as (6) efforts to implement the radio using light-weight, inexpensive plastic and polymer materials, before (7) reflecting on the potential of the new transmitter and possible directions for future work