Machine Learning Based Fluid-Transportation Monitoring and Controlling

The discipline of fluid mechanics is developing quickly, propelled by previously unheard-of data volumes from experiments, field measurements, and expansive simulations at various spatiotemporal scales. The field of machine learning (ML) provides a plethora of methods for gleaning insights from data that can be used to inform our understanding of the fluid dynamics at play. As an added bonus, ML algorithms can be used to automate duties associated with flow control and optimization, while also enhancing domain expertise. This article provides a review of the background, current state, and potential future applications of ML in fluid mechanics. We provide an introduction to the most fundamental ML approaches and describe their applications to the study, modelling, optimization, and management of fluid flows. From the standpoint of scientific inquiry, which treats data as an integral aspect of modelling, experiments, and simulations, the benefits and drawbacks of these approaches are discussed. Since ML provides a robust information-processing framework, it can supplement and potentially revolutionize conventional approaches to fluid mechanics study and industrial applications. &nbsp

Migraine and motion sickness: what is the link?

The brainstem is a structurally complex region, containing numerous ascending and descending fibres that converge on centres that regulate bodily functions essential to life. Afferent input from the cranial tissues and the special senses is processed, in part, in brainstem nuclei. In addition, brainstem centres modulate the flow of pain messages and other forms of sensory information to higher regions of the brain, and influence the general excitability of these cortical regions. Thus, disruptions in brainstem processing might evoke a complex range of unpleasant symptoms, vegetative changes and neurovascular disturbances and that, together, form attacks of migraine. Migraine is linked with various co-morbid conditions, the most prominent being motion sickness. Symptoms such as nausea, dizziness and headache are common to motion sickness and migraine; moreover, migraine sufferers have a heightened vulnerability to motion sickness. As both maladies involve reflexes that relay in the brainstem, symptoms may share the same neural circuitry. In consequence, subclinical interictal persistence of disturbances in these brainstem pathways could not only increase vulnerability to recurrent attacks of migraine but also increase susceptibility to motion sickness. Mechanisms that mediate symptoms of motion sickness and migraine are explored in this paper. The physiology of motion sickness and migraine is discussed, and neurotransmitters that may be involved in the manifestation of symptoms are reviewed. Recent findings have shed light on the relationship between migraine and motion sickness, and provide insights into the generation of migraine attacks

Mechanisms Of Head Injuries In Road Traffic Accidents; A Potential Solution For Data Collection

Despite advances in road safety, head injuries still account for many of the most serious and fatal injuries in road traffic accidents. This PhD thesis provides a summary of knowledge regarding the current position in head injury research with regard to: Previous assertions as to head injury mechanisms Existing head injury criteria The availability of data to explore potential confounding factors in predicting head injury risk and to propose or validate a new injury criterion or criteria. On the basis of the existing information the question was posed, whether it is possible to validate advanced head injury criteria and head models using additional (new) head injury case data so as to make their application more robust in efforts to mitigate future injuries. In order to answer this question, priority was given to the pursuit of new data, offering six degree of freedom time-series data with detailed information on the exact injuries sustained. A working in-ear sensor system was deemed to offer a potential solution in obtaining elusive data regarding the kind of impact events that could cause head injuries for road users. An in-ear accelerometer system used by the FIA Institute was evaluated through experimentation. Then a low-cost solution was developed with the aim to give similar sensor performance for a wider market of potential wearers. The prototype low-cost sensor system was evaluated in a small series of drop tests and also in a very small real-world data collection trial. This evaluation identified a series of issues that need to be resolved before the system can be used to generate valuable data. A viable system is not ready immediately, but could be following modifications to the prototype system evaluated. Taking this revised system, the next step would be to initiate a larger trial to start the collection of high fidelity data and impact event details; in order to address the need for such information and confirm that even the low-cost system would be fit for that purpose

Control techniques for mechatronic assisted surgery

The treatment response for traumatic head injured patients can be improved by using an autonomous robotic system to perform basic, time-critical emergency neurosurgery, reducing costs and saving lives. In this thesis, a concept for a neurosurgical robotic system is proposed to perform three specific emergency neurosurgical procedures; they are the placement of an intracranial pressure monitor, external ventricular drainage, and the evacuation of chronic subdural haematoma. The control methods for this system are investigated following a curiosity led approach. Individual problems are interpreted in the widest sense and solutions posed that are general in nature. Three main contributions result from this approach: 1) a clinical evidence based review of surgical robotics and a methodology to assist in their evaluation, 2) a new controller for soft-grasping of objects, and 3) new propositions and theorems for chatter suppression sliding mode controllers. These contributions directly assist in the design of the control system of the neurosurgical robot and, more broadly, impact other areas outside the narrow con nes of the target application. A methodology for applied research in surgical robotics is proposed. The methodology sets out a hierarchy of criteria consisting of three tiers, with the most important being the bottom tier and the least being the top tier. It is argued that a robotic system must adhere to these criteria in order to achieve acceptability. Recent commercial systems are reviewed against these criteria, and are found to conform up to at least the bottom and intermediate tiers. However, the lack of conformity to the criteria in the top tier, combined with the inability to conclusively prove increased clinical benefit, particularly symptomatic benefit, is shown to be hampering the potential of surgical robotics in gaining wide establishment. A control scheme for soft-grasping objects is presented. Grasping a soft or fragile object requires the use of minimum contact force to prevent damage or deformation. Without precise knowledge of object parameters, real-time feedback control must be used to regulate the contact force and prevent slip. Moreover, the controller must be designed to have good performance characteristics to rapidly modulate the fingertip contact force in response to a slip event. A fuzzy sliding mode controller combined with a disturbance observer is proposed for contact force control and slip prevention. The robustness of the controller is evaluated through both simulation and experiment. The control scheme was found to be effective and robust to parameter uncertainty. When tested on a real system, however, chattering phenomena, well known to sliding mode research, was induced by the unmodelled suboptimal components of the system (filtering, backlash, and time delays). This reduced the controller performance. The problem of chattering and potential solutions are explored. Real systems using sliding mode controllers, such as the control scheme for soft-grasping, have a tendency to chatter at high frequencies. This is caused by the sliding mode controller interacting with un-modelled parasitic dynamics at the actuator-input and sensor-output of the plant. As a result, new chatter-suppression sliding mode controllers have been developed, which introduce new parameters into the system. However, the effect any particular choice of parameters has on system performance is unclear, and this can make tuning the parameters to meet a set of performance criteria di cult. In this thesis, common chatter-suppression sliding mode control strategies are surveyed and simple design and estimation methods are proposed. The estimation methods predict convergence, chattering amplitude, settling time, and maximum output bounds (overshoot) using harmonic linearizations and invariant ellipsoid sets

Unique neural mechanisms of the migraine brain

Whether migraine pathophysiology stems from vascular or centrally-driven origins has been debated for decades. However, facilitated by the development of modern neural imaging techniques and scientific technology, the last century has seen the largest advance in our understanding of migraine. It is now well accepted that sensitization of the trigeminovascular pathway plays a crucial role in the initiation and expression of a migraine. This is supported by experimental human studies that revealed abnormal activity of the trigeminovascular system. This abnormal activity was found particularly in areas of the brainstem, midbrain and hypothalamus during a migraine attack itself and during the interictal period, that is at least 72 hours following and not within 24 hours before a migraine. Research into the premonitory period, the critical 24-hour pain-free period preceding a migraine, is scarce and as a result, there is a gap in our understanding of how and why sensitization occurs. It may be that altered brain function, particularly in brainstem sites, may either trigger a migraine itself or facilitate a peripheral trigger that activates certain pain-processing brain regions, resulting in head pain. As it is impossible to predict when a migraine is imminent, few studies have investigated the premonitory period. Understanding the underlying mechanisms of the migraine cycle has potential to transform the way migraine disorder is treated. The aim of this thesis was to identify functional brain differences throughout the migraine cycle, in particular in the critical 24-hour pain-free period preceding a migraine. The first investigation (Chapter 2) aimed to identify if neural activity within the brainstem and hypothalamus would alter over the migraine cycle. I employed high-resolution functional magnetic imaging (fMRI) to measure ongoing activity patterns reflected through infra-slow oscillations (ISOs) and functional connectivity in the interictal, postdrome and premonitory periods of migraine compared with controls. A comparison between all groups provided evidence of unique activity in the 24-hour period immediately preceding a migraine. Increased ISO activity occurred exclusively in this period in areas of the trigeminovascular system including the spinal trigeminal nucleus (SpV), midbrain periaqueductal gray (PAG), dorsal pons, thalamus and hypothalamus. Remarkably, midbrain and hypothalamic sites were found to display increased functional connectivity and regional homogeneity immediately preceding a migraine suggesting a role for the PAG-hypothalamic interaction in migraine expression. Importantly, interictal and postdrome groups displayed similar activity as control groups, highlighting the unique nature of the premonitory period. It is possible that these increases in ISO power and regional homogeneity result from enhanced amplitude and synchrony of oscillatory gliotransmitter release immediately before a migraine attack, thus supporting the role of astrocytes and gliotransmission in migraine initiation and/or expression. These findings have never been reported in the premonitory period of migraine and reflect altered brainstem and hypothalamic function immediately preceding a migraine. Along with the central nervous system, cerebral vasculature changes have been strongly implicated as critical for migraine initiation. The second investigation (Chapter 3) aimed to build on my previous study by determining whether changes in absolute activity levels, reflected through abnormal cerebral blood flow (CBF), could be identified throughout the migraine cycle. I used pseudocontinuous arterial spin labelling (pcASL) to measure CBF in the interictal, postdrome and premonitory periods of migraine compared with controls. In line with the findings of my first investigation, this analysis revealed distinctive activity in the 24-hour period immediately preceding a migraine with decreased CBF in the hypothalamus, PAG and SpV. In addition, decreased CBF was revealed in higher brain structures such as the visual cortex, orbitofrontal cortex (OFC) and retrosplenial cortex. These findings also reflected alterations in the interictal group with decreases in CBF detected in higher brain structures including the nucleus accumbens, putamen, OFC and ventrolateral prefrontal cortex. Remarkably, decreased CBF in brainstem regions was found only in the period immediately preceding a migraine and these decreases occurred suddenly, as opposed to the decreased CBF found in the higher brain regions which tended to occur gradually throughout the interictal period as the migraine approached. The specialized activity of the brainstem in the period immediately preceding a migraine further emphasizes that brainstem abnormalities are involved in the initiation and/or expression of a migraine. Though many studies have explored CBF during other periods of migraine, this is the first study to measure resting CBF during the 24-hour period immediately preceding a migraine using ASL, and furthermore, to couple ongoing activity patterns (Chapter 2) with absolute brain activity. The first two cross-sectional investigations (Chapters 2 and 3) revealed unique abnormal activity in the 24-hour period immediately preceding a migraine in areas of the brainstem, midbrain and hypothalamus. However, it remains unknown whether similar patterns would be revealed in a longitudinal study when comparing periods throughout an individual’s migraine cycle. To complete this thesis, the third investigation (Chapter 4) aimed to follow the migraine cycle of three migraineurs by imaging them five days a week over four weeks. Due to the cyclic nature of migraine, I expected that when comparing the activity in the 24-hour period immediately preceding a migraine with other periods of migraine within these individuals, the findings would reflect similar patterns as our cross-sectional studies. Indeed, using fMRI I explored resting brainstem activity patterns and found that although resting activity variability was similar in controls and migraineurs on most days, during the period immediately preceding a migraine, brainstem variability increased dramatically. These increases in resting variability were restricted to specific areas of the pain processing pathway including the SpV and dorsal pons. Remarkably, these changes were located in the same brainstem regions which have been shown to be activated during a migraine itself, but again they occurred whilst the individual was not in pain. These increases in brainstem variability were characterised by increased power at ISOs between 0.03-0.06 Hz and they were coupled to increases in resting regional homogeneity directly prior to a migraine. These oscillatory and regional homogeneity changes are consistent with the idea that changes in astrocyte function may precede a migraine and be responsible for its initiation and/or maintenance. These data provide the first evidence of altered brainstem function directly before a migraine throughout the migraine cycle of multiple individuals and provide compelling evidence for the hypothesis that brainstem function is altered immediately before a migraine. Overall, these data reveal that the 24-hour period immediately preceding a migraine possesses unique qualities that may be crucial in the initiation and/or expression of the migraine. My findings reflect abnormal activity of the trigeminovascular system, in particular in areas of the brainstem, midbrain and hypothalamus. I found increases in ongoing activity patterns in the 24-hour period immediately preceding a migraine only, however abnormalities in absolute activity levels were also found in higher brain structures in the interictal period. Finally, when exploring the migraine cycle within three individuals, I found that the 24-hour period immediately preceding a migraine reflected very similar patterns to those revealed in my cross-sectional studies; relatively stable activity until the 24-hour period preceding a migraine, where a sudden over-exaggeration of activity occurred. It seems that migraine is indeed a cyclic disorder with brainstem function oscillating between altered states

Role of pituitary adenylate cyclase-activating polypeptide in nociception and migraine

Energy-efficient buildings can make a major contribution to tackle the world’s climate change and energy use. A number of different environmental certification systems have been created to support energy-efficient and environmentally friendly buildings. In this project simulations are made on a building named Hjältarnas Hus. The building will be used as a support center for those affected by cancer or another critical illness and their families. Hjältarnas Hus will be built in the area next to the University Hospital of Umeå and is planned to be ready for use by the winter 2016/2017. The building project Hjältarnas Hus focuses on sustainability with recyclable materials and aims to achieve the Swedish Environmental Building Certification (Miljöbyggnad) grade GOLD. The main purpose of this project is to study heat transfer through windows. Due to the fact that the facade of Hjältarnas Hus contains large exterior windows, high indoor temperatures are expected during the summer if no solar shading system is installed. The simulations were made in IDA ICE and COMSOL Multiphysics. The focus of this study is to analyze the part of the building that will be used as a library because that part has 90 % windows in the façade. This part is thereby the thermally weakest part of the building envelope since windows are a critical component. The simulations have been based on three milestones. One of the targets was to investigate the temperature gradient that occurs in Hjältarnas Hus library for different ventilation flows, provided that the building achieves the Swedish Environmental Building Certification grade SILVER or GOLD. The second target was to investigate whether the projected solar shading system provides sufficient shading with respect to the certification requirements for Solar heat gain. The third target was to investigate the risk for appearance of external condensation on glass. An investigation of the profitability of an investment in a solar energy generating facility has also been conducted. The result from the simulations showed that the library will never be able to avoid overheating in the summer without any shading system. Even if the ventilation flow is at maximum speed, high temperatures will occur if no shading is installed. The simulations shows that the Swedish Environmental Building Certification grade SILVER can be achieved while the shading system is installed. Risk of external condensation on the window surfaces was greatest during the months of August, September and October. According to the simulations, condensations will appear during 7 % of these months. A calculation from the supplier shows that solar cells are a profitable investment for Hjältarnas Hus. The best option gave a payback period of 9.29 years without any contribution by the State where the investment cost was 950 000 (excl. VAT). För att komma tillrätta med de miljöproblem vi har i världen idag är ett klimatsmart byggande en viktig förutsättning. Som en del i utvecklingen för att minska energi- och resursanvändningen i byggnader har olika certifieringssystem vuxit fram. I detta arbete har simuleringar utförts på en byggnad med namnet Hjältarnas Hus. Byggnaden kommer att fungera som ett anhörighus för familjer där någon familjemedlem drabbats av en svår sjukdom. Hjältarnas Hus kommer att uppföras på området intill Umeå universitetssjukhus i Umeå och planeras att stå klart under vintern 2016/2017. Byggnationen har ett stort fokus på ett hållbart byggande med återvinningsbara material och har ett uppsatt mål om att kunna nå certifieringen av Miljöbyggnad nivå GULD. Detta arbete fokuserar i huvudsak på att undersöka energitransporten genom byggnadens fönsterytor. På grund av att byggnaden kommer att ha stora glaspartier i fasaden förväntas problem med övertemperaturer att uppstå under sommarhalvåret om ingen åtgärd för solavskärmning vidtas. Simuleringarna har utförts i simuleringsprogrammen IDA ICE och COMSOL Multiphysics och har begränsats till ett rum som kommer att brukas som ett allrum/bibliotek då detta rum anses vara byggnadens svagaste länk för att klara det termiska klimatet sommartid. Orsaken till detta är att 90 % av fasaden består av glaspartier. De simuleringar som utförts i detta arbete har baserats på tre delmål. Ett av delmålen var att undersöka mönstret för de temperaturskiktningar som uppstår i Hjältarnas Hus allrum/bibliotek för olika ventilationsflöden med hjälp av simuleringsprogrammet COMSOL Multiphysics. Detta förutsatt att byggnaden klarar certifieringen av Miljöbyggnad nivå GULD eller SILVER med avseende på indikatorn Solvärmelast. Det andra delmålet var att undersöka med hjälp av IDA ICE om den projekterade solavskärmningen ger en tillräcklig avskärmning i rummet för att certifieringen skall kunna uppnås. Det tredje delmålet var att simulera risken för bildning av utvändig kondens på fönsterytorna som uppstår till följd av fönstrens låga U-värden i IDA ICE. Förutom detta har även en utredning kring lönsamheten i en investering i en solcellsanläggning på Hjältarnas Hus takyta genomförts. Resultaten från simuleringarna av temperaturskiktningarna i rummet visade att allrummet/biblioteket aldrig kommer att kunna undvika övertemperaturer under sommarmånaderna om ingen solavskärmning vidtas. Även om ventilationsflödet går på maximal hastighet kommer övertemperaturer att uppnås om ingen solavskärmning är installerad. De alternativ av solavskärmning som studerades för byggnaden visade sig uppfylla kraven som ställs på SILVER-nivån i klassificeringen av Miljöbyggnad med avseende på indikatorn Solvärmelast. Resultaten från studien av bildning av utvändig kondens på årsbasis visade att risken för utvändig kondens på fönsterytorna var störst under månaderna augusti, september och oktober. Under dessa månader bildades det utvändig kondens på fönsterytorna under 7 % av tiden enligt gjorda simuleringar. En investering av solceller för placering på Hjältarnas Hus takyta är lönsamt enligt de beräkningar som erhållits från leverantör. Det bästa alternativet gav en återbetalningsperiod på 9,29 år utan stadsbidrag till en investeringskostnad på ca 950 000 kr (exklusive moms).

FAAH inhibition as a preventive treatment for migraine: A pre-clinical study

Abstract Background Fatty-acid amide hydrolase (FAAH) is an intracellular serine hydrolase that catalyzes the cleavage of endogenous fatty-acid amides, including the endocannabinoid anandamide (AEA). We previously reported that the peripherally restricted FAAH inhibitor URB937, which selectively increases AEA levels outside the central nervous system, reduces hyperalgesia and c-Fos expression in the trigeminal nucleus caudalis (TNC) and the locus coeruleus in an animal model of migraine based on nitroglycerin (NTG) administration. Aim To further investigate the relevance of FAAH inhibition in the NTG animal model of migraine by testing the effects of the globally active FAAH inhibitor URB597. Methods Our experimental approach involved mapping neuronal c-Fos protein expression, measurement of AEA levels in brain areas and in trigeminal ganglia, evaluation of pain-related behavior and quantification of molecular mediators in rats that received URB597 (2 mg/kg i.p.) either before or after NTG administration (10 mg/kg, i.p.). Results Pre-treatment with URB597 significantly reduced c-Fos immunoreactivity in the TNC and inhibited NTG-induced hyperalgesia in the orofacial formalin test. This behavioral response was associated with a decrease in neuronal nitric oxide synthase, calcitonin gene-related peptide and cytokine gene expression levels in central and peripheral structures. Administration of URB597 after NTG had no such effect. Conclusions The findings suggest that global FAAH inhibition may offer a therapeutic approach to the prevention, but not the abortive treatment, of migraine attacks. Further studies are needed to elucidate the exact cellular and molecular mechanisms underlying the protective effects of FAAH inhibition

Experimental Spinal Cord Injury Models in Rodents: Anatomical Correlations and Assessment of Motor Recovery

Human traumatic spinal cord injury (SCI) causes disruption of descending motor and ascending sensory tracts, which leads to severe disturbances in motor functions. To date, no standard therapy for the regeneration of severed spinal cord axons in humans exists. Experimental SCI in rodents is essential for the development of new treatment strategies and for understanding the underlying mechanisms leading to motor recovery. Here, we provide an overview of the main rodent models and techniques available for the investigation of neuronal regeneration and motor recovery after experimental SCI

Ion Channel Disturbances in Migraine Headache: Exploring the Potential Role of the Kynurenine System in the Context of the Trigeminovascular System

Migraine is a primary headache disorder, which is an enormous burden to the healthcare system. While some aspects of the pathomechanism of migraines remain unknown, the most accepted theory is that activation and sensitization of the trigeminovascular system are essential during migraine attacks. In recent decades, it has been suggested that ion channels may be important participants in the pathogenesis of migraine. Numerous ion channels are expressed in the peripheral and central nervous systems, including the trigeminovascular system, affecting neuron excitability, synaptic energy homeostasis, inflammatory signaling, and pain sensation. Dysfunction of ion channels could result in neuronal excitability and peripheral or central sensitization. This narrative review covers the current understanding of the biological mechanisms leading to activation and sensitization of the trigeminovascular pain pathway, with a focus on recent findings on ion channel activation and modulation. Furthermore, we focus on the kynurenine pathway since this system contains kynurenic acid, which is an endogenous glutamate receptor antagonist substance, and it has a role in migraine pathophysiology