Non-linear thermal simulation at system level: Compact modelling and experimental validation

In this work, a general methodology to extract compact, non-linear transient thermal models of complex thermal systems is presented and validated. The focus of the work is to show a robust method to develop compact and accurate non-linear thermal models in the general case of systems with multiple heat sources. A real example of such a system is manufactured and its thermal behaviour is analyzed by means of Infra-Red thermography measurements. A transient, non-linear Finite-Element-Method based model is therefore built and tuned on the measured thermal responses. From this model, the transient thermal responses of the system are calculated in the locations of interest. From these transient responses, non-linear compact transient thermal models are derived. These models are based on Foster network topology and they can capture the effect of thermal non-linearities present in any real thermal system, accounting for mutual interaction between different power sources. The followed methodology is described, verification of the model against measurements is performed and limitations of the approach are therefore discussed. The developed methodology shows that it is possible to capture strongly non-linear effects in multiple-heat source systems with very good accuracy, enabling fast and accurate thermal simulations in electrical solvers

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

Index to 1986 NASA Tech Briefs, volume 11, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1986 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

A review of major centrifugal pump failure modes with application to the water supply and sewerage industries

Centrifugal pumps are one of the world?s most widely used type of pump, having an extensiverange of applications, from food processing to water or sewage transportation. Problems that arisewithin these machines decrease the flow of the fluid within the pipelines, thus interrupting theproduction and transport of the fluid to its destination within the process. This may lead to other partsof the process system slowing down or behaving undesirably. As a result, it is imperative that thesepumps be correctly monitored, diagnosed, maintained or replaced prior to the pump failing catastrophically to reduce downtime, material cost, and labour costs. This paper reviews the major faultmodes that are found in centrifugal pumps, especially those in the water and sewage industry. Attentionis given to the nature of the faults, symptoms shown within the pump that could be utilised for specificfault detection and diagnosis, and any mechanical corrective procedures that exist to help alleviate theproblem. In addition, this paper contains a comparison and critique of previously published work thathas attempted to diagnose the fault modes of centrifugal pumps

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 164

This bibliography lists 275 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1977

Novel engineering and characterization of sensing materials and fluidic devices for neuroscience

Many aspects of neurophysiology such as the pathophysiology of neuropsychiatric illness remain unclear due to challenges in non-invasively probing the brain while considering its chemical and physical heterogeneity. Further investigation of the neurochemicals responsible for neuropsychiatric illness, as indicated by the monoamine hypothesis of depression, is therefore limited without addressing these obstacles. The Hashemi lab studies these neurotransmitters and develops translational tools to minimize challenges associated with in vivo analysis while maximizing the predicative power of in vitro models of the brain. The work in this thesis furthers our understanding of the behaviour of carbon fiber micro-electrodes for serotonin measurement and the fluid dynamics of FSCV measurements. This information is critical for the acquisition of physiologically relevant measurements from translational models of neuropsychiatric illness. In this thesis, I begin by reviewing techniques that have been developed to monitor neurotransmitters in Chapter 1. Next, in Chapter 2, I outline the specific methods used to collect measurements with FSCV/FSCAV and to construct the electrodes and fluidic devices characterized in this work. In Chapter 3, I establish a design criterion for the development of fluidic devices for FSCV measurements. I then use this criterion to design a flow cell for FSCV measurements and challenge its reproducibility and stability. This work enabled the validation of the analyte specific decay and variability of CFMEs. Chapter 4 introduced a simple and inexpensive fabrication protocol for a versatile carbon-based electrode with excellent electrochemical kinetics and sensitivity for serotonin measurements with FSCV. After characterizing the performance of this electrode, it was integrated into a simple polydimethylsiloxane (PDMS) based device to provide a preliminary platform for the optimization of measurements from cells using FSCV (Chapter 5). This work identified adhesion, dead space, electrode geometry, and material rigidity as key parameters in the design of a microfluidic device with an incorporated capacity for FSCV measurements. Chapter 6 concludes the thesis and highlights the future implications of the work. In sum, this work offers novel tools for characterizing sensors for FSCV measurement and a concept for a microfluidic device capable of sensor calibration and measurement from patient-specific in vitro models of the brain. This type of analytical platform would permit the characterization of neurotransmission for preclinical pharmacological screening and/or elucidation of personalized therapies for neuropsychiatric illness.Open Acces

Modeling the fundamental characteristics and processes of the spacecraft functioning

The fundamental aspects of modeling of spacecraft characteristics by using computing means are considered. Particular attention is devoted to the design studies, the description of physical appearance of the spacecraft, and simulated modeling of spacecraft systems. The fundamental questions of organizing the on-the-ground spacecraft testing and the methods of mathematical modeling were presented