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Premature ejaculation (PE) is associated with decreased quality of life, lower confidence and self-esteem, and higher levels of depression, anxiety, and interpersonal difficulties. Here we investigated the effectiveness of vibrator-assisted start–stop exercises for treatment of PE, and whether the treatment effect could be enhanced by an additional psychobehavioral intervention. Fifty participants with a mean age of 41.7 years were included and randomized into two treatment groups and a waiting list control group. Participants were instructed to perform start–stop exercises while stimulating the penis with a purpose-made vibrator, 3 times a week for 6 weeks. Additionally, participants in one of the treatment groups received additional psychoeducation and performed mindfulness meditation-based body scan exercises three times a week. Data were gathered through online questionnaires before and after treatment, as well as 3 and 6 months after treatment. The interventions reduced PE symptoms with large effect sizes (partial η2 = .20 across the three groups, d [95% CI] = 1.05 [.27, 1.82] and 1.07 [.32, 1.82] for treatment groups compared to waiting list control group). The additional psychobehavioral intervention did not further reduce PE symptoms, but did decrease PE-associated negative symptoms such as levels of sexual distress, anxiety, and depression. No side effects were reported. Vibrator-assisted start–stop exercises can be offered as an adequate treatment option for PE. Electronic supplementary material The online version of this article (10.1007/s10508-019-01520-0) contains supplementary material, which is available to authorized users.

Controllable loop thermosyphon (CLT) can be used as a significant temperature management component in solar- and electric-powered cool-storage refrigerators. However, the behaviours of CLT with non-condensable gas (NCG) under active control require further investigation. In this study, air is mixed in working fluid R134a as NCG to evaluate the steady-state and start-stop performances of CLT for selected control modes. CLT with 0–0.62% NCG is tested. The larger the amount of NCG is, the lower the heat transfer rate is. When the mass ratio of NCG reaches 0.62%, the steady-state heat transfer rate varies from 245.0 W to the minimum 118.6 W for different heat sink temperatures. This finding means that CLT loses efficacy due to the excess NCG. In addition, the start-up performances of the two modes decrease as the mass ratio of NCG increases to 0.31% and become entirely unacceptable when NCG reaches 0.47%. By contrast, the stopping time of CLT remains less than 100 s in various conditions. Results indicate that the mass ratio of NCG should be less than 0.47%, and CLT with NCG is suggested to be controlled by the valve in the vapour line.

This paper is aimed to develop operation strategies or high temperature polymer electrolyte fuel cells (HT-PEMFCs) stacks in order to enhance the endurance by mitigating carbon oxidation reaction. The testing protocols are carefully designed to suit the operating cycle for the realistic application. A 5 cell co-flow stack is assembled with BASF Celtec® P membrane electrode assembly (MEA) with an active area of 163.5 cm2. The oxidation rate of carbon is systematically investigated employing potentiostatic experiments under variation of both cell voltage and temperature using on-line mass spectrometry. The experimental results show that more CO2 is measured for the open circuit voltage (OCV) operation, indicating that the lifetime of the stack is strongly affected by a factor of approximately 12–26 between OCV and 700 mV depending on temperature. Protective start-stop algorithms are developed to avoid the formation of aggressive cell potentials. The startup procedures let degrade the catalyst support to a higher extent than the stop procedures, which is presumably due to both OCV exposure and hydrogen front passing through the anode. A model for lifetime prediction is developed from carbon corrosion experiments and validated with a durability test for 1,562 cycle events.

A crescente preocupação com os impactos ambientais das atividades do setor automobilístico têm aumentado a regulamentação governamental em relação ao consumo de combustível e redução de emissões, principalmente na Europa, pioneira na implementação de tais regulamentações. Dessa forma, a indústria automotiva vem desenvolvendo estratégias para se adaptar a esses novos requisitos, e nesse sentido, o uso de sistemas start-stop nos veículos vem aumentando. Este sistema visa reduzir as emissões e o consumo de combustível, desligando o motor em condições de marcha lenta com o veículo estacionário, seja em sinais de trânsito ou engarrafamentos. Tal sistema, mais amplamente aplicado para veículos de passageiros, também foi introduzido para veículos médios, como ônibus e caminhões médios com rotas urbanas. Um grande desafio na implementação start-stop, no entanto, é a alteração das tensões aplicadas aos principais componentes do motor, como pistão, anéis de pistão e bronzinas, pois a variação de temperatura e o fornecimento de lubrificação para eles é intermitente com o desligamento cíclico do motor. Como os testes de durabilidade de tais componentes usando bancadas dinamométricas comuns são extremamente caros e demorados, novas estratégias de teste têm sido exploradas recentemente. Neste trabalho, o principal objetivo foi ajudar na instalação de uma bancada de testes de bronzinas desenvolvida pela Daimler AG, simulando a operação de seus motores de médio porte MDEG, e analisar seus primeiros resultados. O banco de provas é basicamente composto de cilindros hidráulicos simulando a forca da combustão e um virabrequim acionado por um motor elétrico. Os primeiros testes, discutidos neste trabalho, mostram as dificuldades de desenvolver novos métodos de teste, como problemas no sistema de condicionamento de óleo, o desenvolvimento de um programa de operação similar a motores de combustão e as medições de desgaste, bem como a falta de capacidade de aquisição de dados de teste. No entanto, o trabalho mostra o potencial de tal banco de testes depois de os obstáculos explorados serem superados, como uma maneira rápida e simples de testar bronzinas e, possivelmente, outros componentes principais do motor. Além disso, o trabalho sugere que a associação deste experimento com ferramentas computacionais pode fornecer resultados ainda mais completos, contribuindo ainda mais para o desenvolvimento de motores capazes de suportar a implementação de sistemas start-stop. The growing concern about the environmental impacts of the automobile sector activities has increased governmental regulations regarding fuel consumption and emissions reduction, mainly in Europe, pioneer in the implementation of such regulations. Thereby, the automotive industry has been developing strategies to adapt itself to these new requirements, and in that sense, the use of start-stop systems in the vehicles has been increasing. This system aims to reduce emissions and fuel consumption by stopping the engine at idle conditions, whether at traffic lights or in traffic jams. Such a system, more widely applied for passenger vehicles, has also been introduced for medium duty vehicles such as buses and medium trucks with urban routes. A major challenge in the start-stop implementation, however, is the alteration of the stresses applied to core engine components, such as piston, piston rings and bearings, since the temperature variation and lubrication supply for them is intermittent with the cyclic engine shutdown. As durability tests for such components using common dynamometric test benches are extremely expensive and time consuming, new test strategies have been recently explored. In this work, the main goal was to support the installation of a bearing test bench developed by Daimler AG, simulating the operation of their medium duty MDEG engines, and analyze its first results. The test bench is basically composed of hydraulic cylinders simulating the combustion load and a crankshaft rotated by an electric motor. The first tests, discussed in this work, show the difficulties of developing new test methods, such as problems in the oil conditioning system, the development of an operation program similar to regular engines and the wear measurements, as well as the lack of data acquisition capacity. However, the work shows the great potential of such a test bench after the explored obstacles have been overcome, as a quick and simple way to test bearings, and possibly other core engine components. In addition, the work suggests that the association of this experiment with computational tools can provide even more complete results, further contributing to the development of engines capable to withstand the implementation of start-stop systems.

The impact of start-stops on the thickness of lubricating films in the Elasto-Hydrodynamic Lubrication (EHL) contacts in grease lubricated rolling bearings is different from that in oil lubricated bearings. This paper shows that the film thickness drops to zero quickly due to the absence of hydrodynamic effects during a stop. It quickly increases to an unexpected large value when the bearing is stopped for a long time and started up again, although this large value only lasts for a very short time. This is due to additional track replenishment during the stop leading to an initially thicker film than expected. This increase is found to be determined by the rotational speed of the bearing, stop-time, base oil viscosity and width of the contacts. The start-stop effect is similar for unidirectional and oscillating speeds, provided that the stopping time is long enough.

This bachelor thesis focuses on combustion engines especially on four-stroke spark-ignition engines and their current modern trends such as downsizing, variable valve timing, start-stop system, hybrid and hydrogen drive in the automotive industry. The first part of the thesis is a brief description of the history of combustion engines, their basic distribution and key parts which the engine is designed together with a cooling, electric and suction system from. The second part describes modern trends, their use and subsequent application in passenger cars.

This work presents contributions to the modeling, control and management of an hybrid uninterrupted power supply (UPS) based on Otto cycle power generator set and lead acid battery bank. The proposed configuration is called hybrid due to the presence of two energy storage elements: i) the fuel fed the Otto cycle internal combustion engine (ICE) of the generator set and ii) a lead acid battery bank, which can be recharged from the grid or from the generator. With the hybridization it is possible to add up the advantages of UPS’s such as uninterrupted power supply and high output energy quality with the advantages of power generator sets, such as high autonomy and lower installation cost for high autonomy. In addition, with the hybrid topology it is possible to explore degrees of freedom that do not exist in the independent configurations, such as: i) variable speed operation and ii) start-stop operation of the MCI in order to reduce consumption/ emissions in lower loads, (iii) use of Otto cycle engine with lower cost in relation to a Diesel ICE. The hybrid UPS is composed of an Otto cycle internal combustion engine (ICE), a three-phase/three-wire rectifier, which can be connected via contactors to the grid, or to the permanent magnet synchronous generator (PMSG), a battery bank connected to the DC bus through a bi-directional boost converter, and a three-phase/four-wire inverter at the output. Experimental results are provided indicating that variable speed operation can achieve a reduction of up to 32% in specific fuel consumption, depending on the load range. For start-stop operation, the reduction in specific fuel consumption can reach up to 39%, depending on the load range. Este trabalho apresenta contribuições a modelagem, controle e gerenciamento de uma fonte ininterrupta de energia (UPS) híbrida baseada em grupo motor ciclo Otto e bateria chumbo ácido. A configuração proposta é denominada híbrida devido a presença de dois armazenadores de energia: i) o combustível para alimentar o motor a combustão interna (MCI) ciclo Otto do grupo motor gerador e ii) um banco de baterias chumbo ácido, a qual pode ser recarregado pela rede ou pelo gerador. Com a hibridização é possível agregar as vantagens das UPSs tais como, ininterruptibilidade de fornecimento de energia e alta qualidade de energia da tensão de saída, com as vantagens dos grupos motores geradores, tais como, elevada autonomia e menor custo de instalação para autonomias elevadas. Além disso, com a topologia híbrida é possível explorar graus de liberdade não existentes nas configurações independentes, tais como: i) utilização de velocidade variável e ii) operação em regime start-stop no MCI afim de reduzir consumo/emissões em baixas cargas, iii) utilização de motor ciclo Otto com menor custo em relação a um MCI Diesel. A UPS híbrida é composta por um motor a combustão interna (MCI), um retificador trifásico a três/quatro fios, o qual pode ser conectado através de contatoras à rede, ou ao gerador síncrono de ímãs permanente (PMSG), um banco de baterias conectado ao barramento através de um conversor boost bidirecional, e um inversor a quatro fios na saída. Resultados experimentais são apresentados indicando que a operação em velocidade variável pode alcançar um redução de até 32% no consumo específico de combustível, dependendo a faixa de carga. Já para a operação em regime start-stop a redução no consumo específico de combustível pode alcançar até 39%, dependendo da faixa de carga.

Start-stop systems are widely used in the car industry today but have not yet been fully implemented in the heavy-duty vehicle industry. The greater loads arising in the engines leads to excessive wear of the hydrodynamic bearings during starts and stops which has a distinct impact on the machine´s lifetime performance and reliability. This master thesis involves a comparative study of how different surface topographies of a shaft affects hydrodynamic bearing wear during start and stop conditions. The objective was to see if one can extend the bearing lifetime by doing minor changes to the shaft surface. This has been done by redesigning an existing start-stop test rig, increasing its operating system oil temperature to 90°C to provide a more accurate description of the bearing environment, to be able to conduct a series of start-stop cycling experiments. Upon examination of the experiment results, it becomes clear that a more polished surface of the shaft does reduce bearing wear significantly during starts and stops. It was also noticed that a more polished shaft surface does reach full-film lubrication at a lower rotational speed of the shaft, separating the shaft and the bearing surfaces. Start-stoppsystem används idag i stor utsträckning inom bilindustrin men har ännu inte blivit implementerat fullt ut i den tunga fordonsindustrin. De större belastningarna som uppstår i motorn leder till överdrivet slitage på de hydrodynamiska glidlagren under start och stopp och har en tydlig inverkan på maskinens livslängd och pålitlighet. Detta examensarbete har innefattat en jämförande studie om hur olika axelytor påverkar nötningen av hydrodynamiska glidlager vid start och stoppförhållanden. Målet var att se ifall man kan lyckas förlänga lagrets livslängd genom att genomföra mindre förändringar av axelytan. Detta har utförts genom att omkonstruera en befintlig start-stopprigg, ökat oljesystemets driftstemperatur till 90°C för att ge en mer exakt beskrivning av den riktiga lagermiljön, för att sedan ha utfört en serie start och stopp experiment. Resultaten från experimenten visade tydligt att en mer polerad axelyta minskar lagerslitningen avsevärt under start och stopp. Det noterades också att en mer polerad axelyta ger fullfilmssörjning vid en lägre axelrotationshastighet, varvid axeln och lagerytorna separeras.

Fragestellung: In der Hüftendoprothetik wird primär der artikulationsbedingte Verschleiß bei der Etablierung neuer Gleitpaarungen adressiert. Darüber hinaus können erhöhte Reibmomente ursächlich sein für hohe Torsionsbelastungen in der intramodularen Konusverbindung[zum vollständigen Text gelangen Sie über die oben angegebene URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2016)

Increasing demands for lower emissions from heavy trucks and buses creates new demands on the components in the engine. One such component is the journal bearing which is used at many positions in the engine. Implementing a start-stop system in a truck engine leads to that the crankshaft journal bearing gets worn out too quickly. A journal bearing is a sliding bearing with a constant flow of oil. When the journal starts rotating an oil film is formed between the bearing and the journal, separating the journal from the bearing surface when the rotational speed is high enough. When this happens a hydrodynamic oil film is formed. During start and stop the bearing and journal passes through boundary and mixed lubrication regimes. The increase in starts and stops leads to a vast increase in the time that the bearing is experiencing boundary and mixed lubrication. During these regimes the journal comes in contact with the bearing surface and eventually leads to wear. This thesis has compared two new materials provided by Höganäs AB with an existing bearing as a reference material. The new materials were laser cladded onto bearing shells and sent to Scania for grinding and testing. The thought was to use a start-stop test rig at KTH that simulates start-stop cycles. The reference bearings were first run in the test rig, but when the shells with the new materials arrived it turned out that they would not fit in the test rig. This created the need for a new test method on a short notice and a reciprocating tribometer at Scania was chosen. The tribometer underwent a number of modifications to be able to fit the samples. Five tests with each new material and the reference material were carried out. The tests ran for 60 minutes except for a long term test that ran for 600 minutes. The results showed that the material designated “S”, which had a solid lubricant, had a coefficient of friction similar to the reference material, but produced less wear and could handle a higher load. The thesis has also proved that the start-stop test rig at KTH works well and can deliver reliable results. På grund av skärpta miljökrav för tunga lastbilar och bussar ökar kraven på motorns komponenter. En av dessa komponenter är radialglidlager som används på många platser i motorn. Implementering av start-stoppsystem i en lastbilsmotor leder till att vevaxellagren slits ut i förtid. Ett radialglidlager är ett glidlager med ett kontant tillflöde av olja. När axeln börjar rotera skapas det en oljefilm mellan lagerytan och axeln. När rotationshastigheten är tillräckligt hög bär oljefilmen lasten och separerar axeln och lagerytan. Då har det bildats en fullfilm. Under start och stopp passerar lagret genom smörjregimerna gränsskiktssmörjning och blandsmörjning. Ökningen av start och stopp leder till en stor ökning av tiden som lagret upplever gränsskiktsoch blandsmörjning. Under dessa regimer är axeln och lagerytan i kontakt vilket leder till nötning. Detta examensarbete har jämfört två nya material från Höganäs AB med ett existerande lager som referens. De två nya materialen påsvetsades på lagerskålar och skickades till Scania för att slipas och testas. Tanken var att använda en start-stopprigg på KTH som simulerar startstoppcykler. Till att börja med kördes referenslagren i riggen, men när lagerskålarna med de nya materialen levererades visade det sig att de inte passade i testriggen. Detta innebar att en ny testmetod behövdes tas fram med kort varsel och valet föll på en reciprocerande tribometer på Scania. Tribometern var tvungen att modifieras för att proverna skulle passa. Fem test med varje material utfördes. Varje test tog 60 minuter, förutom ett långtidstest som kördes under 600 minuter. Resultaten visade att materialet kallat ”S”, vilket inkorporerade ett fast smörjmedel, hade en friktionskoefficient som liknade referensmaterialets, men producerade mindre nötning och klarade av en högre last. Examensarbetet har också kunnat påvisa att start-stoppriggen på KTH fungerar väl och kan leverera konsekventa resultat.

Increasing demands for lower emissions from heavy trucks and buses creates new demands on the components in the engine. One such component is the journal bearing which is used at many positions in the engine. Implementing a start-stop system in a truck engine leads to that the crankshaft journal bearing gets worn out too quickly. A journal bearing is a sliding bearing with a constant flow of oil. When the journal starts rotating an oil film is formed between the bearing and the journal, separating the journal from the bearing surface when the rotational speed is high enough. When this happens a hydrodynamic oil film is formed. During start and stop the bearing and journal passes through boundary and mixed lubrication regimes. The increase in starts and stops leads to a vast increase in the time that the bearing is experiencing boundary and mixed lubrication. During these regimes the journal comes in contact with the bearing surface and eventually leads to wear. This thesis has compared two new materials provided by Höganäs AB with an existing bearing as a reference material. The new materials were laser cladded onto bearing shells and sent to Scania for grinding and testing. The thought was to use a start-stop test rig at KTH that simulates start-stop cycles. The reference bearings were first run in the test rig, but when the shells with the new materials arrived it turned out that they would not fit in the test rig. This created the need for a new test method on a short notice and a reciprocating tribometer at Scania was chosen. The tribometer underwent a number of modifications to be able to fit the samples. Five tests with each new material and the reference material were carried out. The tests ran for 60 minutes except for a long term test that ran for 600 minutes. The results showed that the material designated “S”, which had a solid lubricant, had a coefficient of friction similar to the reference material, but produced less wear and could handle a higher load. The thesis has also proved that the start-stop test rig at KTH works well and can deliver reliable results. På grund av skärpta miljökrav för tunga lastbilar och bussar ökar kraven på motorns komponenter. En av dessa komponenter är radialglidlager som används på många platser i motorn. Implementering av start-stoppsystem i en lastbilsmotor leder till att vevaxellagren slits ut i förtid. Ett radialglidlager är ett glidlager med ett kontant tillflöde av olja. När axeln börjar rotera skapas det en oljefilm mellan lagerytan och axeln. När rotationshastigheten är tillräckligt hög bär oljefilmen lasten och separerar axeln och lagerytan. Då har det bildats en fullfilm. Under start och stopp passerar lagret genom smörjregimerna gränsskiktssmörjning och blandsmörjning. Ökningen av start och stopp leder till en stor ökning av tiden som lagret upplever gränsskiktsoch blandsmörjning. Under dessa regimer är axeln och lagerytan i kontakt vilket leder till nötning. Detta examensarbete har jämfört två nya material från Höganäs AB med ett existerande lager som referens. De två nya materialen påsvetsades på lagerskålar och skickades till Scania för att slipas och testas. Tanken var att använda en start-stopprigg på KTH som simulerar startstoppcykler. Till att börja med kördes referenslagren i riggen, men när lagerskålarna med de nya materialen levererades visade det sig att de inte passade i testriggen. Detta innebar att en ny testmetod behövdes tas fram med kort varsel och valet föll på en reciprocerande tribometer på Scania. Tribometern var tvungen att modifieras för att proverna skulle passa. Fem test med varje material utfördes. Varje test tog 60 minuter, förutom ett långtidstest som kördes under 600 minuter. Resultaten visade att materialet kallat ”S”, vilket inkorporerade ett fast smörjmedel, hade en friktionskoefficient som liknade referensmaterialets, men producerade mindre nötning och klarade av en högre last. Examensarbetet har också kunnat påvisa att start-stoppriggen på KTH fungerar väl och kan leverera konsekventa resultat.

While there has been substantial body of work in the field of journal bearing research, much of it is today theoretical or simulated due to today’s computing power. Scania produces experimental data from motor testing, but these are expensive and time consuming. Furthermore there is a difficulty in keeping a sufficiently controlled environment, which at times makes it hard to draw conclusions from testing results. They therefore wish to develop a test-rig which can evaluate friction and wear in journal bearings. This thesis is a continuation of a project in the course Advanced Machine Design given at KTH Royal Institute of Technology. During this thesis the test-rig has been manufactured, built, and evaluated. Furthermore software for the test-rig was developed. Information on journal bearings, risk assessment and signal noise handling were sought. Mechanical development was done with Autodesk Inventor, while Matlab was used for software development. Factorial design was utilised when designing tests and compared to a simple theoretical model. Test results showed promising results for Stribeck curve-producing tests, with good resemblance to known frictional values and trends. Furthermore the test-rig showed good repeatability for replicated tests and produced wear on the bearing shells used. During a prolonged test, the shaft and support-bearings were damaged and requires servicing to be in an operational state. The test-rig requires to be further verified, but the tests that were carried out showed valuable and reliable information on wear and frictional values. Keywords: journal bearing, hydrodynamic lubrication, wear, start-stop, test-rig Även om en betydande mängd forskning inom glidlager och fullfilmslager har genomförts så är med dagens datorkapacitet en stor del av resultaten numera teoretiska eller simulerade. Medan Scania producerar experimentella resultat, så är dessa dyra och tidskrävande. Vidare är det ibland svårt att hålla en tillräckligt kontrollerad miljö för att dra slutsatser från proverna. Med en dedikerad testrigg som kan tillförlitliga resultat tas fram billigare och snabbare. Detta examensarbete är en fortsättning av kursen Avancerad Maskinkonstruktion som ges vid Kungliga Tekniska Högskolan. Under detta examensarbete har testriggen tillverkats, byggts och utvärderats. Vidare har programvara för testriggen utvecklats. Informationssökning gjordes på glidlager, fullfilmslager, riskbedömning och signalbrushantering. Mekanisk utveckling har gjorts i Autodesk Inventor, medan Matlab användes för mjukvaruutveckling. Faktorial design har nyttjats vid utformningen av tester. Resultaten jämfördes med en enkel teoretisk modell. Testresultaten visade lovade resultat för Stribeck kurva-producerande tester, med god likhet till kända friktionsvärden och trender. Testriggen visade god reproducerbarhet vid replikerade tester. Testriggen producerar slitage på samtliga testade lagerytor. Under ett längre test så har axel och stödlager skadats, varför service behövs för att testriggen skall vara i brukbart skick. Testriggen kräver ytterligare verifiering, men resultaten från de prov som genomförts visar att test-riggen ger värdefull och tillförlitlig information om slitage och friktion kunna utrönas. Nyckelord: glidlager, hydrodynamisk smörjfilm, nötning, start-stop, testrigg

This study combines local electrochemical diagnostics with ex situ analysis to investigate degradation mechanism associated to start-up/shut-down (SU/SD) of PEMFC and mitigation strategies adopted in automotive stacks. Local degradation resulting from repeated SU/SD was analyzed with and without mitigation strategies by means of a macro-segmented cell setup provided with Reference Hydrogen Electrodes (RHEs) at both anode and cathode to measure local electrodes potential and current. Accelerated Stress Test (AST) for start-up with and without mitigation strategies are proposed and validated. A ten-fold acceleration of performance loss due to un-mitigated SU/SD has been calculated with respect to AST for catalyst support. Under mitigated SU/SD, instead, a strong degradation was observed as localized at cathode inlet region (i.e. −38% ECSA loss and −22 mV voltage loss after 200 cycles) due to local potentials transient reaching up to 1.5 V vs RHE. These localized stress conditions were additionally reproduced in a zero-gradient and a new AST protocol (named start-up AST) was proposed to mimic the potential profile observed upon SU/SD cycling. Representativeness of the start-up AST for real world degradation was confirmed up to 200 cycles. Platinum dissolution and diffusion/precipitation within the polymer electrolyte was shown to be the dominant mechanism affecting performance loss.