Due to good energy-efficiency of electrohydraulic compact drives a cooling aggregate often is not installed. The operating temperature is governed by the complex interaction between dissipative heat input and passive heat output. This paper targets the simulation of the thermo-energetic behaviour of an electrohydraulic compact drive by means of a lumped parameter model in order to predict the operating temperature. The developed thermo-hydraulic model is validated against measurements utilising thermocouples and a thermographic camera to capture temperatures. The results show, that the presented methodology enables a satisfying accurate prediction of the thermo-energetic behaviour of electrohydraulic compact drives. A further analysis of simulation results is given, highlighting the power losses and heat rejection capabilities of different components. Finally, measures for the improvement of the heat rejection capabilities are studied.

This paper studies a method for active electrohydraulic force compensation in industrial scale high power applications. A valve controlled cylinder moves a mass using the force of inertia to compensate for the reaction forces of an industrial process. Two strategies for force compensation are developed and investigated in a 160 ton clamping unit of an injection moulding machine to significantly reduce the excitation. Results of the different strategies are shown and evaluated. Advantages and drawbacks of the developed electrohydraulic force compensation are discussed.

In 2016 it is 70 years since the first patent for a two-stage servovalve was filed, and 60 years since the double nozzle-flapper two-stage valve patent was granted. This paper reviews the many alternative servovalve designs that were investigated at that time, focusing on two-stage valves. The development of single-stage valves – otherwise known as direct drive or proportional valves – for industrial rather than aerospace application is also briefly reviewed. Ongoing research into alternative valve technology is then discussed, particularly focussing on piezoelectric actuation and the opportunities afforded by additive manufacturing.

Thesis (DPhil (Social Work))--Stellenbosch University, 2008. / It is a common phenomenon that women’s sexual desire diminishes in relationships, yet, to date, limited research has been done locally on this topic. International studies indicate that low sexual desire affects more than half of women, and that an even greater proportion of women indicate that they have sexual intercourse with their husbands without they themselves having a desire to do so. In spite of this, there is an expectation in society that couples should continue to have an active sex life. Low sexual desire may lead to distress in the individual or discord in the couple, and in this aspect the practitioner can render a service. The aim of this study was to gain a better understanding of the life-world of women with low sexual desire towards their life-partners, and the extent to which this causes her distress or impedes on her relationship. The objectives of the study thus included providing an overview of models of sexual response, an evaluation of the diagnostic criteria for sexual dysfunctions, and an exploration of factors affecting the experience of sexual desire, including the role of social scripts on sexual behaviour. The context for the study is provided by a review of relevant literature, and a qualitative study with a phenomenological interpretative approach was executed. Data gathering focused on a nonprobable purposive sample of ten participants, and used an interview schedule with open-ended questions. Seven themes emerged from the analysis of the data, namely (1) perceptions of sexual desire, (2) experience of sexual desire, (3) experience of sex life without desire, (4) the perceived impact of low desire on the individual or the relationship, (5) personal reasons for decline in desire, (6) relationship factors affecting sexual desire, and (7) the experience of low desire in the socio-cultural context. It was found that ‘desire’ is difficult to conceptualise, that women put a higher premises on the emotional component of desire, and that there is a difference between innate sexual desires and desire that is evoked by stimuli. Reasons for low sexual desire include an array of personal medial, psychological, and life context factors, and in many cases the lack of desire is specific to the present life-partner. Women are especially sensitive to a wide variety of aspects in the relationship and with regards to their partners, and it emerged that even in happy and intimate relationships low sexual desire is experienced. Women experience a loss of emotional intimacy as a result of low sexual desire but do not necessarily feel that their low desire is abnormal. The impact on the relationship is limited mostly because women concede to sex for many reasons, including a need for emotional intimacy. Many strategies, including faking orgasms, are implemented to cope with sexual relationships in the absence of desire. It also appears that social scripts have a big influence on the inception of negative perceptions on sexuality, and generate unreasonable and idealistic expectations of sexual experiences in long-term relationships. Several recommendations flowed from the findings and conclusions. The most important recommendation is that professional people should gain a deeper understanding of the complexity of the phenomenon of low desire in women, in order to render a more effective therapeutic intervention.

Introduktion Majoriteten av alla ungdomar använder sociala medier för att kommunicera med sina vänner genom bilder, chatt och forum eller för informationsinhämtning. På dessa mötesplatser finns reklam och innehåll som är könsstereotypa. Många ungdomar känner press att leva upp till stereotyperna vilket gör att man lägger upp förskönande bilder för att efterlikna idealen. Syftet med denna litteraturöversikt var att beskriva hur självbilden hos ungdomar i åldrarna 13-25 kan påverkas av innehållet i sociala medier. Metod Vetenskapliga artiklar hittades i databaserna CINAHL och PubMed. Genom en litteraturöversikt tematiserades de använda artiklarna och utifrån dem framkom fem teman. Resultat De fem teman som hittades var Grupptryckets, Den sociala jämförelsens, Smalhetsidealets, Träningsbudskapets och Kostbudskapets inverkan på självbilden. Grupptryck kunde leda till missnöje kring den egna kroppen vilket var vanligare hos tjejer än killar. För tjejer var smalhetsidealet mest dominerande medan det för killar var styrketräning. Att inte leva upp till idealen kunde även leda till depressiva symptom och ätstörningar. Diskussion Att konsumera idealbilder av män och kvinnor kan ge upphov till en orealistisk press på sig själv men det kan också fungera som motivation. / Introduction The majority of young people use social media to communicate with their friends through photos, chats and forums or to find information. Advertisement and content in social media often portrays gender stereotypes. Many young people feel pressured to live up to the stereotypes and uploads beautified images to mimic ideals. The aim of the study was to describe how the content in social media could influence the self-image of adolescents aged 13-25. Method Scientific articles were found in the databases CINAHL and PubMed. The articles were thematized and five themes emerged through a literature review. Results The five themes that emerged were the effect Peer pressure, Social comparison, Drive for thinness, Training and Food related content had on the self-image among adolescents. Peer pressure could lead to body dissatisfaction. The drive for thinness dominated among girls while the most dominating ideal for boys were a muscular body. Failure to live up to the ideals could lead to depressive symptoms and eating disorders. Discussion Consuming ideal images of men and women could lead to an unrealistic pressure on themselves but it could also serve as motivation.

More than 30% of the population suffers from obesity, which increases the risk of death and secondary health problems. Body fat [white adipose tissue (WAT) and brown adipose tissue (BAT)] are innervated and regulated by the sympathetic nervous system (SNS). WAT stores energy, while BAT generates heat for thermoregulation. Fat also has sensory innervations, but the roles of sensory nerves are still being elucidated. Hence, understanding the neuroanatomy of the SNS innervations of fat and the neural regulation of fat metabolism will be valuable for advancing obesity treatment. Using trans-synaptic tract tracers with unique fluorescent proteins, we defined and compared the SNS innervations of visceral fat [mesenteric WAT (MWAT)] and subcutaneous fat [inguinal WAT (IWAT)] and of IWAT and interscapular BAT (IBAT) in Siberian hamsters. MWAT and IWAT have moderately shared SNS innervations within the hindbrain, but separate SNS innervations in rostral regions. In contrast, IWAT and IBAT have relatively separate SNS circuitries throughout the brain yet some overlap in SNS nuclei known to regulate thermogenesis. We tested for the presence of functional coordination between IWAT and IBAT defined by overlap in IWAT SNS and IBAT SNS innervations. When IBAT function was impaired by SNS denervation, IWAT SNS drive, thermogenic activity, and beige adipocyte recruitment increased in cold exposed hamsters likely through coordination with IWAT SNS pathways. Conversely, we found that only SNS drive to IWAT increased during acute food deprivation suggesting that populations of SNS neurons singly innervating each fat depot may contribute to differential SNS drive to fat. Lastly, we demonstrated that IWAT sensory nerves mediate the functional coordination between IWAT and IBAT and the regulation of SNS drive to fat. The absence of IWAT sensory feedback via sensory denervation differentially decreased SNS drive to IBAT and IWAT itself, but not to MWAT, retroperitoneal WAT, and epididymal WAT in cold exposed hamsters. Collectively, the studies in this dissertation provide neuroanatomical evidence of separate and shared SNS brain sites likely receiving sensory signaling and regulating SNS drive to fat, and direct evidence of the roles of SNS and sensory nerves innervating fat to energetic homeostasis and thermoregulation.

Doctor of Philosophy / Department of Electrical and Computer Engineering / Behrooz Mirafzal / In this dissertation, a new topology for Direct-Drive Wind Turbines (DDWTs) with a new power electronics interface and a low-voltage generator design is presented. In the presented power electronics interface, the grid - side converter is replaced by a boost Current Source Inverter (CSI) which eliminates the required dc-bus capacitors resulting in an increase in the lifetime of DDWTs. The inherently required dc-link inductor for this topology is eliminated by utilizing the inductance of the Permanent Magnet Synchronous Generator (PMSG). The proposed three-phase boost CSI is equipped with Reverse-Blocking IGBTs (RB-IGBT) and the Phasor Pulse Width Modulation (PPWM) switching pattern to provide a 98% efficiency and high boost ratios ([superscript V]LL/V[subscript dc]) up to 3.5 in a single stage. In this dissertation, Phasor Pulse Width Modulation (PPWM) pattern for the boost – CSI is also modified and verified through simulation and experimental results. In order to realize potential capabilities of the boost inverter and to assist its penetration into renewable energy systems, the boost inverter dynamic behaviors are studied in this dissertation. Then, the developed models are verified using circuit simulations and experiments on a laboratory-scale boost – CSI equipped with RB-IGBTs. The developed dynamic models are used to study the stability of the boost – CSI through root locus of small signal poles (eigenvalues) as control inputs and load parameters vary within the boost inverter's operating limits. The dynamic models are also used to design the control schemes for the boost – CSI for both stand-alone and grid-tied modes of operation. The developed controllers of the boost – CSI are verified through simulation and experimental results. In this dissertation, the boost – CSI steady-state characterization equations are also developed and verified. The developed boost – CSI is used to replace the grid - side converter in a DDWT. A reliability analysis on the power electronics interface of an existing and developed topology is presented to demonstrate the increase in the mean time between failures. The boost – CSI enables conversion of a low dc voltage to a higher line-to-line voltage enabling the implementation of a low-voltage generator. This further enables a reduction in the number poles required in DDWT generators. The feasibility of the presented low-voltage generator is investigated through finite element computations. In this dissertation, a 1.5MW low-voltage generator designed for the proposed topology is compared with an existing 1.5MW permanent magnet synchronous generator for DDWTs to demonstrate the reduction in the volume, weight, and amount of permanent magnet materials required in the generator. The feasibility of the developed system is supported by a set of MATLAB/Simulink simulations and laboratory experiments on the closed-loop stand-alone and grid-tied systems.

Ce mémoire a pour but d’élucider l’analyse et l’évaluation nietzschéennes du sens et de la portée de la figure de Socrate dans les cultures antique et moderne. Pour ce faire, nous nous pencherons d’abord sur la question de l’identité de Socrate, ce qui permettra d’introduire une distinction centrale à l’analyse de Nietzsche, soit celle entre la doctrine et la personnalité du célèbre Athénien. En effet, Nietzsche isole la personnalité de Socrate, qu’il circonscrit à partir des notions d’instinct, de pulsion et d’affect, de sa doctrine, qu’il appelle le socratisme et qu’il définit à partir de l’équation socratique raison = vertu = bonheur. Ensuite, nous développerons les trois éléments sur lesquels il s’appuie pour expliquer que Socrate ait pu séduire les Grecs, soit le fait qu’il fut un grand érotique, qu’il introduisit une nouvelle forme de joute à Athènes et qu’il apparut comme étant un médecin pour ses contemporains. Cette question des raisons permettant d’expliquer que Socrate ait pu séduire les Grecs est déterminante pour Nietzsche, puisque c’est de là qu’il est amené à se demander qui est ce Socrate et quel a été son véritable impact sur la culture, soit les deux questions qui sont au cœur de ce qu’il appelle « le problème de Socrate ». Enfin, nous nous pencherons sur le diagnostic que le philosophe allemand pose sur le célèbre Athénien ainsi que sur son évaluation de l’impact du socratisme sur les cultures antique et moderne, après quoi nous présenterons l’inversion des valeurs que Nietzsche tente d’opérer dans sa propre culture. Nous verrons alors qu’il cherche entre autres par cette inversion des valeurs à nous libérer du socratisme, car il est d’avis que cette doctrine dévalorise toute forme d’agir puisant ses motifs dans ce qui relève de l’inconscient et survalorise une morale luttant contre les pulsions dominantes en nous. / The purpose of this thesis is to investigate Nietzsche’s analysis and assessment of the meaning and the impact of Socrates’ character on the classical and modern culture. To that effect, I will emphasize the question of Socrates’ identity, in order to introduce the crucial issue in Nietzsche’s analysis, namely the distinction between Socrates’ doctrine and his character. Nietzsche isolated Socrates’ character – which he defined through the categories of instinct, drive, and affect – from his doctrine, which he labelled socratism and defined through the Socratic equation reason = virtue = happiness. This thesis explores the three core elements Nietzsche used to explain how Socrates was able to seduce the Greeks: not only was Socrates a very erotic figure, he also introduced a new form of debate to Athens, and was considered an eminent physician by his contemporaries. Socrates’ appeal to the Greek is of fundamental importance to Nietzsche, since it prompted him to question Socrates’ inherent character, and his true impact on Athenian culture. It thus forms the crux of what he called “the problem of Socrates.” Nietzsche’s understanding of socratism as well as its impact on classical and modern culture allows him to revaluate all values within his own culture. To that effect, I reveal Nietzsche’s critiques of socratism – in particular, his belief that society needed to be liberated from socratism, since it denies all agency to individuals. Given that it was strongly motivated by the unconscious, socratism, according to Nietzsche, overemphasizes a certain morality in the struggle against our dominant impulses.

Enclosed herein, in accordance with the requirements of the Department of English, College of Humanities and Sciences, and the VCU Graduate School, Virginia Commonwealth University, Richmond, Virginia, regarding thesis submission, arrangement, and abstraction, is the novel entitled Skyline, in which one Jameson Price, of Fredericksburg, Virginia, aged 19, embarks upon a journey of self-exploration, financial gain, and physical labor, and experiences for the first time (or maybe second) the tumults of love. Upon his enrolment in the Civilian Conservation Corps (CCC) in 1936, he is taken to Camp Saddleback, near New Puckett, Virginia, situated on the Blue Ridge Mountains to the east of the Shenandoah Valley. Here he assists in the creation of the Shenandoah National Park, and develops and explores relationships with fellow CCC boys and local residents—both positive and negative relationships, all with consequences that will affect all of their lives, forever.

Le travail réalisé dans le cadre de cette thèse vise à l'approfondissement des connaissances sur l'impact de l'environnement gestationnel sur le développement de la commande respiratoire chez le nouveau-né. La respiration est une activité rythmique et autonome. La maturation des réseaux neuronaux impliqués dans son contrôle commence au cours de la gestation et persiste pendant la période postnatale. Le contrôle respiratoire est donc particulièrement susceptible à des variations de l'environnement intra-utérin. Nous avons étudié l'effet de deux stress gestationnels chroniques distincts : l'exposition à des cannabinoïdes et l'exposition à une hypoxie prénatale. A l'aide de techniques intégrées telles que la pléthysmographie à corps entier, éléctrophysiologiques comme la préparation de tronc cérébrale isolé ou les tranches de bulbes et immunohisto- et neurochimiques, nous avons pu caractériser l'impact des stress prénataux étudiés sur la plasticité respiratoire développementale. Nous avons pu établir un rôle central de l'anandamide dans la modulation de la commande respiratoire, probablement via des mécanismes noradrénergiques. L'exposition prénatale au WIN 55,212-2 induit une hyperventilation basale chez la souris nouveau-née qui semble relever d'altérations périphériques. Elle induit également une accentuation de la réponse centrale à l'hypoxie aigue et affecte l'apparition d'irrégularités respiratoires telles que les apnées. Quant à l'hypoxie prénatale, elle induit une hyperventilation basale d'origine centrale ainsi qu'une augmentation de l'activité catécholaminergique du tronc cérébrale. / Breathing is an autonomic rhythmic activity. The maturation of the neuronal networks responsible for breathing control begins in early gestation and persists throughout the neonatal period. This renders breathing control particularly susceptible to early insults arising from the intra uterine environment. We have studied the effects of two such gestational stress factors, namely prenatal exposure to cannabinoids and to gestational hypoxia. We use a wide array of in vivo and in vitro techniques in order to characterise the effect of the adverse intra uterine environment on the development of respiratory control. These include integrated techniques such as whole body plethysmography, electrophysiological preparations (en bloc and brainstem slice recordings) as well as immunohisto- and neurochemical approaches. We show that the prenatal stress factors induce developmental respiratory plasticity. This translates as heightened basal ventilation, observed following prenatal exposure to both cannabinoids and hypoxia. Comparisons between in vivo and in vitro techniques reveal a peripheral origin for the alterations observed following prenatal exposure to cannabinoids, suggesting a perturbation of the initiation and/or integration of information from the peripheral carotid bodies. Following prenatal hypoxia, respiratory perturbations have a central origin and can thus be observed in reduced preparations such as brainstem slice recordings. Neurochemical and immunohistochemical assays also reveal alterations in the bioaminergic modulation of the respiratory rhythm generator, perhaps underpinning the observed effects on respiratory control.