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- Schmidt, Bernard, 1981-
(författare)
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Toward Predictive Maintenance in a Cloud Manufacturing Environment : A population-wide approach
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The research presented in this thesis is focused on improving industrial maintenance by using better decision support that is based on a wider range of input information. The core objective is to research how to integrate information from a population of similar monitored objects. The data to be aggregated comes from multiple disparate sources including double ball-bar circularity tests, the maintenance management system, and the machine tool’s controller. Various data processing and machine learning methods are applied and evaluated. Finally, an economic evaluation of the proposed approach is presented. The work performed is presented in five appended papers.Paper I presents an investigation of cloud-based predictive maintenance concepts and their potential benefits and challenges.Paper II presents the results of an investigation of available and potentially useful data from the perspective of predictive analytics with a focus on the linear axes of machine tools.Paper III proposes a semantic framework for predictive maintenance, and investigates means of acquiring relevant information from different sources (i.e., ontology-based data retrieval).Paper IV presents a method for data integration. The method is applied to data obtained from a real manufacturing setup. Simulation-based evaluation is used to compare results with a traditional time-based approach.Paper V presents the results from additional simulation-based experiments based on the method from Paper IV. The aim is to improve the method and provide additional information that can support maintenance decision-making (e.g., determining the optimal interval for inspections).The method developed in this thesis is applied to a population of linear axes from a set of similar multipurpose machine tools. The linear axes of machine tools are very important, as their performance directly affects machining quality. Measurements from circularity tests performed using a double ball-bar measuring device are combined with event and context information to build statistical failure and classification models. Based on those models, a decision-making process is proposed and evaluated. In the analysed case, the proposed approach leads to direct maintenance cost reduction of around 40 % compared to a time-based approach.
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| 2. |
- Wang, H Fredrik
(författare)
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Neuronal tracers for fine caliber spinal primary afferents and their response to peripheral nerve injury
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The isolectin B4 from Griffonia simplicifolia I (B4) and soybean agglutinin from the plant Glycine max (SBA), have been shown to bind to rat small-diameter dorsal root ganglion (DRG) neurons, and to fibers and presumed terminals in laminae I-II of the spinal cord dorsal horn. In the present thesis, these lectins and/or their horseradish peroxidase (HRP) conjugates, have been investigated in the rat with regard to their usefulness as selective neuronal markers of and axonally transported tracers for somatic and/or visceral spinal primary afferents with fine caliber, including unmyelinated, axons. In addition, binding and transport of B4 and SBA/SBA-HRP have been examined after peripheral nerve injury. In the fifth lumbar DRG, B4 binding and retrogradely transported SBA were found mainly in neurons of small size, and to comprise about half of the total number of DRG neurons, respectively. About half of the SBA cells bound B4, indicating that two different but overlapping sub-populations of small DRG neurons are recognized by these two lectins. Almost all of the B4-, and 85% of the SBA-positive neurons were not immunoreactive for RT97, an antibody which recognizes DRG neurons giving rise to myelinated axons. Calcitonin gene-related peptide (CGRP) immunoreactivity was found in 59% of the B4 binding and in 43% of the SBA transporting DRG cells. Seventeen per cent of the B4 neurons and 33% of the SBA cells contained substance P (SP). A few B4 (9%) and SBA (2.4%) cells were immunoreactive to somatostatin (SOM). Besides, almost all DRG neurons that were positive for fluoride-resistant acid phosphatase (FRAP) were B4-positive. Injections of B4-HRP or SBA-HRP into the sciatic nerve resulted in labeling in the DRG in the same neurons that bound B4 or SBA. In the spinal cord gray matter, such injections gave rise to labeling of axons and presumed terminals in somatotopically appropriate regions of the superficial dorsal horn, most prominently in the inner part of lamina II for both tracers, although intense labeling in lamina I was additionally found for SBA/SBA-HRP. B4-HRP injections into DRGs resulted in labeling in the cutaneous, sural nerve and in the sympathetic, greater splanchnic nerve, but not in the muscle, lateral and medial gastrocnemius nerves. Such injections also resulted in labeling of free and lanceolate-like nerve endings in the hind paw skin. Electron microscopic examination of the labeled nerves showed that B4-HRP labeled exclusively unmyelinated axons. To study spinal afferents from a parasympathetic nerve, tracer injections were made into the urinary bladder wall. These injections resulted in retrograde and transganglionic labeling at the sixth lumbar and the first sacral spinal levels, most effectively when using cholera toxin B subunit (CTB)-HRP. In the DRGs, CTB-positive neurons were mainly RT97- negative (85%) and showed a large overlap with CGRP (71%) and SP (36%). A few CTB neurons showed galanin-, but not SOM-, or vasoactive intestinal polypeptide-immunoreactivity or contained FRAP. In the spinal cord, CTB-HRP labeled fibers were found to form bundles of lateral and medial collateral projections, and to extend into the dorsal gray commissural region and/or into the spinal parasympathetic nucleus. To study neuronal changes of fine caliber primary afferents following peripheral nerve injury, the sciatic nerve was lesioned unilaterally. In the transport studies, B4 or SBA/SBA-HRP was injected into both the previously lesioned and into the contralateral nerve, as control. In the binding studies, no such injections were made. By 2 weeks after nerve transection and ligation, spinal cord binding and transganglionic transport of B4 had disappeared completely, whereas binding and transport of SBA/SBA-HRP were unchanged. At 6-14 weeks, the SBA/SBA-HRP labeling was weaker but not completely depleted, while B4 labeling was still absent. At 8- 16 months, both B4 binding and B4 transport had partially recovered. Results from the crush injury cases, studied by B4, showed a partial decrease of binding and transport by 2 weeks and a complete recovery as early as after 10 weeks. This thesis study suggests that both B4 and SBA are useful markers and transganglionic tracers for two different but overlapping sub-populations of somatic unmyelinated spinal primary afferent neurons. Both of the populations of neurons labeled by B4 and SBA contain FRAP, SOM, CGRP and SP. While B4 is also a useful tracer for primary afferents in the sympathetic, greater splanchnic nerve, CTB is better suited as a tracer for afferents in the parasympathetic, pelvic nerve. Both B4 and SBA are useful for studying effects of peripheral nerve lesions on fine caliber primary afferents, although with somewhat different temporal scales.
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| 3. |
- Zhang, Shi-Jin, 1957-
(författare)
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Regulation of Intracellular Calcium in Brown Adipocytes
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Intracellular Ca2+ is considered a primary regulator of cell function. In the present study, the control and the effects of intracellular Ca2+ in brown adipocytes have been investigated. Cytosolic Ca2+ levels ([Ca2+]i) are the resultant of the activity of Ca2+ transport systems. Results concerning Ca2+transport systems in the plasma membrane, endoplasmic reticulum and mitochondria are presented.[Ca2+]i, monitored with Fura-2/AM, is increased when brown adipocytes are stimulated with norepinephrine (NE). The NE effect is mediated via a1-adrenoceptors and involves both release from intracellular Ca2+ stores and influx of extracellular Ca2+. The NE-induced [Ca2+]i response could be desensitized by pretreatment with NE. The desensitization is also mediated by a1-receptors and intracellularly by increased [Ca2+]i and calmodulin but not by protein kinase C. The kinetics of the desensitization are similar to those of inhibition of protein synthesis or transcription and the desensitization is associated with a comparable decrease in the number of a1-receptors.Mitochondrial Ca2+ levels ([Ca2+]m) were monitored within brown adipocytes with mitochondrially targeted aequorin. [Ca2+]m was not a simple reflection of [Ca2+]i; rather, evidence is presented for the existence of a b-adrenergic, cAMP-mediated signal that augments the [Ca2+]m/[Ca2+]i ratio. This signal causes the mitochondria to sequester Ca2+ even in the absence of increased cytosolic levels. Inhibition of mitochondrial Ca2+ uptake augments the cytosolic responses. Mitochondria may thus play an important role even in cytosolic Ca2+homeostasis in brown adipocytes.Chronic treatment of brown adipocytes with NE resulted in marked alterations of cytosolic Ca2+ handling, but the mitochondria retained their ability to sequester Ca2+during adrenergic stimulation, i.e. under conditions when UCP1 should be active.The effects of an increase in [Ca2+]i involve activation of a cAMP phosphodiesterase, and the presence of this component explains the unusual kinetic characteristics of norepinephrine-induced cAMP accumulation. [Ca2+]i is also involved in the regulation of gene expression: increased [Ca2+]i interacts synergistically with cAMP in the control of c-fos expression which may be of significance for regulation of cell proliferation and differentiation.It was concluded that Ca2+ is a primary regulator of physiological functions in brown adipocytes. The Ca2+ transport systems in brown adipocytes are involved in the regulation of intracellular and intraorganellar Ca2+. Changes of the free cytosolic Ca2+ concentration by hormone stimulation induces the activation of many physiological processes.
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