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This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London Strict emissions legislations and continuous race for improvement of fuel economy urge to develop more efficient and cleaner IC engines for commercial and private use. Engine downsizing has been shown as an effective means to reduce the vehicle’s fuel consumption but the full potential of engine downsizing is limited by the knocking combustion at boosted operations and the presence of pumping loss at part load conditions. A variable valve train system can be used to minimise the knocking combustion by implementing Miller and Atkinson cycles through alteration of the effective compression ratio (ECR) at high load via Early Intake Valve Closure (EIVC) or Late Intake Valve Closure (LIVC), as well as reducing the pumping loss at part load. In this work, a single cylinder direct injection Spark Ignition (SI) gasoline engine equipped with an electro-mechanical valvetrain system named iVT (intelligent Valve Technology) by Camcon was set up and used to investigate the potential benefits of the iVT. Engine experiments were carried out at 1500 and 3000rpm with various valve profiles including EIVC and LIVC with single and two intake valve mode as well as early intake Maximum Opening Position (MOP) at 35% and 40% MOP. Their effects on engine performance and emissions were measured and analysed at 4, 6, 9 and 12.6bar net IMEP. Results showed that EIVC and LIVC profiles were successful in reducing the fuel consumption with two valve mode at low loads thanks to lower pumping loss and at high loads where spark timing was knock limited. Those profiles also resulted in lower emissions. In particular, the LIVC profile reduced the NOX concentration by up to 20% at low loads due to lowest ECR. Single valve mode operations also provided improved fuel economy at 4bar and 12.6bar net IMEP when combined with EIVC profiles. However, the most significant reduction in ISFC was achieved with early MOP. With combination of LIVC and early MOP, ISFC was reduced by up to 5.4% at low load and by up to 7.1% at high load compared to the baseline profile at 1500rpm.

Intake and exhaust valves in Internal Combustion Engines (ICEs) are traditionally actuated by means of fixed cam-based mechanisms that allow to implement just one valve lift profile for all engine operating conditions. Instead, the possibility to introduce flexibility in varying valve lift parameters, such as valve timing and/or maximum valve lift position, has been widely investigated as an effective technique to improve more and more the efficiency of ICEs and as consequence reducing fuel consumptions. In this regard different Variable Valve Actuation (VVA) technologies have been developed and nowadays adopted in modern ICEs although most of them are still based on camshaft. This is a first step ahead towards the development of future camless engines where valve lift and timing could be adjusted freely from valve to valve. In this scenario we have focussed studies on a prototype of Electro-Hydraulic Valve Actuator (EHVA) proposed as an enabling VVA technology for implementing advanced combustion concepts in future camless engines. Unfortunatley, each EHVA system needs to be properly managed to be able to vary opening duration and lift of engine valve actuated by it. To this aim, we present a preliminary design of a cycle-by-cycle controller aimed at regulating such valve parameters. The proposed control strategy relies on two controllers operating separately for regulating the opening duration and lift of an engine valve. The performance of cycle-by-cycle controller are evaluated through simulations and numerical results presented.

The effects of oral vitamin D supplements on vaginal health in postmenopausal women with vulvovaginal atrophy (VVA) was evaluated. A double-blinded, randomized placebo-controlled trial was conducted for 12 weeks to investigate changes on vaginal maturation index (VMI), vaginal pH, and the visual analog scale (VAS) of VVA symptoms. The vitamin D group received oral ergocalciferol, at 40,000 IU per week, while the placebo group received an identical placebo capsule. Eighty postmenopausal women were enrolled. There were no significant differences in baseline characteristics between both groups. In an intention-to-treat analysis, VMI, vaginal pH, and VAS of VVA symptoms showed no significant differences between both groups at the six and 12 weeks. However, the mean difference of VMI in the vitamin D group between baseline and at six weeks showed significant improvement (5.5 + 16.27, p &lt, 0.05). Moreover, the mean vaginal pH and VAS of VVA patients in the vitamin D group were significantly improved at both six and 12 weeks compared to baseline. The oral vitamin D supplementation for 12 weeks potentially improves vaginal health outcomes in postmenopausal women with VVA symptoms, demonstrated by the improved mean VMI, vaginal pH, and VAS at six and 12 weeks between baseline, however, no significant differences were observed from the placebo treatment.

Contexte et objectif: La préservation de la qualité de vie après un traitement anticancéreux est un défi majeur pour les survivantes du cancer du sein. Environ 42 à 70 % des patients qui reçoivent une thérapie systémique pour le cancer du sein, y compris une thérapie endocrinienne, développeront une atrophie vulvo-vaginale (AVV). Pour ces patientes, les traitements à base de gel couramment proposés pour les applications topiques sont restrictifs. Récemment, des approches thérapeutiques innovantes et non hormonales, telles que la thérapie laser, ont fait leur apparition. L'objectif de cette étude de faisabilité est d’étudier la sécurité et l'efficacité de la thérapie au laser CO2 chez les femmes ayant des antécédents de cancer du sein. Matériel et méthodes: Cette étude monocentrique prospective a porté sur 20 patientes atteintes d'AVV qui ont été traitées à l'hôpital universitaire Henri Mondor entre 2017 et 2018. Nous avons inclus des patientes ayant un indice de santé vaginale (IHV) < 15 et une contre-indication à l'administration d'hormones en raison d'antécédents de cancer du sein. Deux séances de laser au dioxyde de carbone ont été utilisées. Le traitement a été administré selon les paramètres suivants : programme « vaginal Tight », FinePulse (pulse largeur de 0,9 ms) et densité énergétique de 11,5 J/cm2 qui permet de couvrir 70 % de la zone vaginale ciblée à traiter. Toutes les patientes ont eu leur visite de suivi à un (M1), trois (M3) et six (M6) mois après le premier traitement pour évaluer l'efficacité du traitement sur l'atrophie vulvo-vaginale. Le score d'indice de santé vaginale et le score de détresse sexuelle féminine (FSD) ont été utilisés pour évaluer l'efficacité du traitement et son impact sur la qualité de vie sexuelle. Un score ≥ 11 a été associé à un dysfonctionnement sexuel. Les scores d'indice de santé vaginale et FSD ont été évalués avant traitement et mois1 M1, M3 et M6 du suivi. Résultats: L’âge moyen des patientes était de 56,1 ± 8,8 ans (min–max, 27–69 ans). Dix-sept des 20 patientes avaient déjà été ménopausées (âge moyen de la ménopause, 51,25 ± 1,5 ans). Au moment de l'inclusion, les scores moyens du score d'indice de santé vaginale et du FSD étaient respectivement de 10,58 ± 1,71 et 21,36 ± 15,10. Quatorze patientes sur 20 (70 %) avaient un score de détresse sexuelle féminine ≥ 11 au départ. À M1, le score d'indice de santé vaginale moyen a augmenté de manière significative pour atteindre 13,42 ± 2,3 (p = 0,03), ce qui représente une amélioration de 21 % par rapport au niveau de référence. Une amélioration persistante et significative du score d'indice de santé vaginale a été observée à M6, le score passant à 16,75 ± 4,23 après le traitement (p < 0,0001), ce qui représente une amélioration de 34 % par rapport au score moyen de départ. La moyenne su score FSD à M1 était de 19,83 ± 13,57, ce qui représente une diminution de 7 % par rapport aux scores de base (p < 0,01). À M3, le score de détresse sexuelle féminine a diminué de manière significative pour atteindre 13,88 ± 15,58, ce qui représente une amélioration de 35 % (p = 0,006). Il a augmenté à 10,35 ± 14,7 à M6, ce qui représente une amélioration de 52 % (p = 0,001). À M3, 35 % des patients avaient un score de détresse sexuelle féminine > 11, et à M6, seuls 15 % avaient un score de détresse sexuelle féminine > 11. Aucun effet secondaire n'a été signalé lors du suivi. Conclusion: Cette étude de faisabilité pilote a montré que le traitement par laser au dioxyde de carbone semble être une méthode efficace et sûre pour améliorer la trophicité et diminuer la sécheresse de la muqueuse vaginale chez les femmes atteintes d'atrophie vulvo-vaginale qui s'est développée après un traitement systémique du cancer du sein.

Käytettävyys on yksi tavoitteiden toteutumista mittaavista tunnusluvuista, joka kuvaa kohteen kykyä olla tilassa, jossa se tarvittaessa kykenee suorittamaan siltä vaadittua toimintoa. Tässä työssä käsitellään kahden Yara Suomen Uudenkaupungin tehtailla sijaitsevan automaattisen suursäkityskoneen vikaantumista ja toimintaongelmia sekä näiden vaikutusta koneiden käytettävyyteen. Tutkimuksen tavoite on selvittää säkityskoneiden käytettävyyttä alentavat tekijät, niiden aiheuttajat sekä tutkia ratkaisuja käytettävyyden parantamiseksi. Tavoitteena on lisäksi selvittää, mitä asioita koneista tulee mitata ja mitä tietoja kerätä, jotta analysointi on jatkossa helpompaa ja luotettavampaa sekä tarkastella vikojen aiheuttamia kustannuksia. Tutkimuksessa käytetty data koneiden toiminnasta ja vikaantumisesta on pääasiassa peräisin kahdesta eri tietokannasta. Toiminnanohjausjärjestelmän vikahistoriaa on käytetty kunnossapitoa vaativien vikojen sekä niistä aiheutuvien kustannusten selvittämiseen. Koneiden häiriöilmoitushistorian avulla on selvitetty lyhyitä tuotantokatkoksia aiheuttavat toimintaongelmat. Järjestelmien datan ollessa osittain erittäin heikkolaatuista, on dataa täydennetty syvähaastattelujen avulla. Haastattelujen avulla on myös tunnistettu aiemmilla toimenpiteillä hallintaan saadut ongelmat sekä määritetty kunkin toistuvan vian ja häiriön aiheuttama seisokkiaika. Seisokkiaikojen ja käyntiaikatietojen perusteella on määritetty kunkin toistuvan vian ja häiriön aiheuttama epäkäytettävyys, jota puolestaan on käytetty mittarina toistuvien vikojen ja häiriöiden seurausten vakavuuden vertailussa. Käytettävyysvaikutusten perusteella tiedetään, mihin ongelmiin tulee kohdistaa voimavaroja ja millaisia parannuksia niiden ratkaisemisella on mahdollista saavuttaa. Koko koneiden tarkan käytettävyyden määrittämiseksi lähtötiedoissa on epävarmuustekijöitä, mutta häiriöt ja raportoidut viat alentavat käytettävyyttä n. 15 %. Osaa laitteistosta tarkastellaan yksityiskohtaisesti RCM-analyysin avulla ja muu laitteisto käsitellään kevyemmin. RCM-analyysissä käytettyjä analysointimenetelmiä ovat vika- ja vaikutusanalyysi sekä vikapuuanalyysi. RCM-analyysin tuloksena on tunnistettu muun muassa tehokkaat kunnossapitomenetelmät, modifiointitarpeet, varautumistarpeet vikatilanteisiin sekä jatkotutkimuskohteet. Työn tuloksena havaittiin myös kehitystarpeita ohjeistuksessa, datan keräyksessä, suorituskyvyn mittauksessa ja säkin laadussa. Häiriöhistorian perustella toimintahäiriöitä tulee niin paljon, että operaattorien jatkuva läsnäolo on pakollista. Työtä voidaan pitää onnistuneena ja hyödyllisenä. Tuloksia voidaan hyödyntää muilla yrityksen toimipaikoilla, joissa vastaavia suursäkityslaitteistoja on käytössä tai sellaisen hankkimista suunnitellaan. Työn menetelmät soveltuvat myös muiden yrityksen laitteistojen toiminnan ja vikaantumisen tutkimiseen sekä käytettävyyden, kunnossapitomenetelmien ja muiden kehityskohteiden määrittämiseen.

It is commonly recognized that the paths for improving fuel consumption (BSFC) in a spark-ignition engine at part-load require more advanced valve actuation strategies, which largely affect the pumping work. Since several years, many different solutions have been proposed, characterized by different levels of complexity, effectiveness, and cost. Valve systems currently available on the market allow for variable phasing (VVT - Variable Valve Timing), and/or lift (VVA - Variable Valve Actuation). Usually VVT devices are applied on intake and exhaust camshafts, in the “phased” or “unphased” configuration, as well. VVA devices are instead commonly mounted on the intake camshaft. More recent VVA systems also allow for a double intake valve lift during a single engine cycle (multi-lift), or may include a small intake pre-lift during the exhaust stroke. The latter solutions may determine further BSFC reductions. Alternatively, an external- EGR circuit can be considered, as well.

Vehicle emissions regulations are continuing to grow more challenging requiring near-zero levels of pollutant emissions. Nitric oxide (NOx) emissions are heavily regulated with the emission limit expected to become 1/10th of its present limit by 2021. In order to meet the new regulations, improvements in both the engine and the exhaust aftertreatment system are required. Exhaust gas recirculation (EGR) is used to reduce the NOx produced by the engine while the aftertreatment system converts most of the engine-out emissions to safer gases before releasing them to the atmosphere. One of the main challenges with the aftertreatment system is that it requires to operate at a certain minimum temperature before it is effective. Variable valve actuation (VVA) can be used to improve the thermal management of the aftertreatment system- first to accelerate the warmup following a cold start and then to maintain its temperature economically. Using VVA, negative valve overlap (NVO) was looked at as form of internal EGR, where exhaust gas is trapped inside the cylinder. Experiments showed a 70°C increase in exhaust gas temperature while maintaining engine out NOx. A literature survey was performed on exhaust gas re-induction as another means of internal EGR. Internal EGR has potential to be an effective means of reducing NOx and improving aftertreatment thermal efficiency in future diesel engines.

As emission regulations getting more stringent and the demand for fossil fuel growing, it is crucial to develop advanced technologies for internal combustion engine to lower emissions and fuel. Strategies such as diesel oxidation catalysts (DOC) for UHC, diesel particulate filters (DPF) for PM, and selective catalytic reduction (SCR) for NOx have been developed and implemented to convert harmful emissions to innocuous species. However, the efficiencies of these after-treatment systems are heavily temperature dependent. Heavy-duty over-the-road trucks require periodic active diesel particulate filter regeneration to clean the filter of stored particulate matter. These events require sustained temperatures between 500 and 600 °C to complete the regeneration process. Engine operation during typical 65 mile/hour highway cruise conditions (1200 rpm/7.6 bar) results in temperatures of approximately 350 °C, and can reach approximately 420 °C with late fuel injection. This necessitates hydrocarbon fueling of a diesel oxidation catalyst or burner located upstream of the diesel particulate filter to reach the required regeneration temperatures. These strategies require increased fuel consumption, and the presence of a fuel-dosed oxidation catalyst (or burner) between the engine and particulate filter. This work experimentally demonstrates that, at the highway cruise condition, deactivation of valve motions and fuel injection for two or three (of six) cylinders can instead be used to reach engine outlet temperatures of 520 - 570 °C, a 170 - 220 °C increase compared to normal operation. This is primarily a result of a reduction in the air-to-fuel ratio realized by reducing the displaced cylinder volume through cylinder deactivation. HDFTP drive cycle has more than half of the fuel consumed at high speed/high load conditions. Strategies using valve train flexibility were investigated experimentally to improve fuel economy at high speed/high load conditions. IVC modulation at high speed is an effective way of achieving higher volumetric efficiency from dynamic charging in turn help fuel efficiency. Intake valve closure from nominal 565 CAD to 595 CAD at high speed enables dynamic charging and thus increases EGR fraction with air-to-fuel ratio maintained. The strategy of "dynamic charging" helps get fuel economy benefit by around 1.25% without sacrificing BSNOx.

Vulvovaginal atrophy (VVA) is a chronic disorder that commonly occurs in postmenopausal women, whose symptoms are recognized among the most frequent and bothersome symptoms associated with menopause. The principal therapeutic goal in managing VVA is to relieve symptoms as well as to restore the vaginal environment to a healthy state. However, despite its high prevalence and negative impact on quality of life, VVA is underreported by women, underrecognized by gynecologists, and therefore, undertreated. In the light of the new development of treatment options for VVA, we here provide an updated expert opinion on the management of VVA. In particular, we strongly recommend that HCPs proactively start an open discussion with their postmenopausal patients about urogenital symptoms. Treatment should be started as early as the first symptoms of VVA occur and should be maintained over time, due to the chronicity of the conditions. Many treatment options are now available and therapy should be individualized, taking the woman’s preference in consideration.

Various solutions are being proposed to improve the performance of spark-ignition internal combustion engines. A very effective approach is the downsizing technique, which allows the reducing of the Brake Specific Fuel Consumption (BSFC) at part load, while maintaining the required performance at high load. On the other hand, the above technique may cause substantial BSFC detrainments at high load because of the onset of knocking combustions. In the present work, a turbocharged spark ignition engine equipped with a fully flexible valve system is numerically investigated by a 1D model (GT-Power™). Proper “user routines” are used to simulate the turbulent combustion process and the knock phenomenon. In a first stage, the engine model is validated against experimental data under both high and part load operations, in terms of overall performance and combustion evolution. The validated model is then integrated in a multipurpose commercial optimizer (modeFRONTIER™) with the aim to identify the engine calibrations that maximize the load and minimize the BSFC under high load knock-limited operations at a speed of 3000 rpm. The effects of different intake valve strategies are compared. The optimized operating parameters are the waste-gate valve opening and the air-to-fuel ratio, while the combustion phasing is automatically adjusted to avoid the knock onset. Proper constraints are assigned for the boost pressure, turbocharger speed, and turbine inlet temperature. The adopted optimization process shows the capability to reproduce the experimentally-identified calibration with satisfactory accuracy. In addition, the results underline the BSFC advantages related to an early intake valve closure strategy with respect to a Full Lift one, due to a better combustion phasing and a reduced mixture over-fuelling. The developed automatic procedure allows for a “virtual” engine calibration on a completely theoretical basis and proves to be very helpful in reducing the engine development costs and time-to-market.

Electro-mechanical valve actuators (EMVA) are a solution for implementing variable valve actuation in internal combustion engines. Their use can increase engine power, reduce fuel consumption and pollutant emissions, while significantly improving engine efficiency. The control of this actuator is a complex task since non-smooth nonlinearities, parameter variations and external forces strongly affect plant dynamics. In addition, the impact of the valve at its end-strokes translates into mechanical wear and unacceptable noise, and in the worst case the electromagnet may also fail to catch the valve, causing system failure. The design of effective control strategies to ensure valve capture with low impact velocities is therefore essential for the correct functioning of such a mechatronic device. In this paper, the control problem of reducing the impact velocity at "landing" known in the literature as soft landing control, is tackled via novel cycle-by-cycle adaptive force compensation control algorithms. Two schemes are presented: a discrete adaptive proportional integral controller to regulate landing velocity to a preassigned set-point, and a gradient descent method based controller to automatically achieve the minimum admissible impact velocity. The effectiveness of both methods in limiting landing velocities is shown numerically using a high predictive simulator of the EMVA system, when considering unknown varying environmental conditions, such as internal friction and external gas pressure forces.

In the paper, the potentialities offered by an advanced valve lift design are numerically analyzed. In particular, the study is carried out by a 1D approach and regards the characterization of a VVA strategy named “ pre-lift” applied to a downsized turbocharged four-cylinder engine. The pre-lift consists of a small, almost constant lift of the intake valve during the exhaust stroke, so to increase the valves overlapping. The results show a benefit on the fuel economy and on the gas-dynamic noise at part load and a substantial increase in the delivered torque at full load, while preserving the fuel consumption.

It is widely recognized that air-fuel mixing, combustion and pollutant formation inside internal combustion engines are strongly influenced by the spatial and temporal evolution of both marco- and micro- turbulent scales. Particularly, in spark ignited engines, the generation of a proper level of turbulence intensity for the correct development of the flame front is traditionally based on the onset, during the intake and compression strokes, of a tumbling macro-structure. Recently, in order to both reduce pumping losses due to throttling and develop advanced and flexible engine control strategies, fully variable valve actuation systems have been introduced, capable of simultaneously governing both valve phasing and lift. Despite the relevant advantages in terms of intake system efficiency, this technology introduces uncertainties on the capability of the intake port/valve assembly to generate, at low loads, sufficiently coherent and stable structures, able therefore to promote adequate turbulence levels towards the end of the compression, with relevant effects on the flame front development. It is a common knowledge that 3D-CFD codes are able to describe the evolution of the in-cylinder flow field and of the subsequent combustion process with good accuracy; however, they require too high computational time to analyze the engine performance for the whole operating domain. On the contrary, this task is easily accomplished by 1D codes, where, however, the combustion process is usually derived from experimental measurements of the in-cylinder pressure trace (Wiebe correlation). This approach is poorly predictive for the simulation of operating conditions relevantly different from the experimental ones. To overcome the above described issues, enhanced physical models for the description of in-cylinder turbulence evolution and combustion to be included in a 1D modeling environment are mandatory. In the present paper (part I), a 0D (i.e. homogeneous and isotropic) phenomenological (i.e. sensitive to the variation of operative parameters such as valve phasing, valve lift, intake and exhaust pressure levels, etc.) turbulence model belonging to the K-k model family is presented in detail. The model is validated against in-cylinder results provided by 3D-CFD analyses carried out

The present paper reports 1D and 3D CFD analyses of the air-filter box of a turbocharged VVA engine, aiming to predict and improve the gas-dynamic noise emissions through a partial re-design of the device. First of all, the gas-dynamic noise at the intake mouth is measured during a dedicated experimental campaign. The developed 1D and 3D models are then validated at full load operation, based on experimental data. In particular, 1D model provides a preliminary evaluation of the radiated noise and simultaneously gives reliable boundary conditions for the unsteady 3D CFD simulations. The latter indeed allow to better take into account the geometrical details of the air-filter and guarantee a more accurate gas-dynamic noise prediction. 3D CFD analyses put in evidence that sound emission mainly occur within a frequency range of 350 to 450 Hz. Starting from the above result, the original air-box design is modified through the installation of a single Helmholtz resonator, taking into account layout constraints and the influence on engine performance, as well. First, the isolated air-box is studied through a 3D FEM approach to compute the Transmission Loss (TL) parameter both for the original and the modified design. This analysis is employed to verify the noise abatement in the frequency range of interest, for a zero-mean flow. Then, the new intake system configuration is investigated under actual engine operation, through unsteady 3D CFD simulations. The resulting reduction in the gas-dynamic noise is verified both in terms of overall radiated SPL and frequency spectrum at full and part load operating conditions, as well. The proposed integrated 1D-3D approach demonstrated to be a useful tool for the design and the analysis of new geometrical intake system configurations, aiming to improve the engine acoustic performance without significant penalties on the delivered power and fuel consumption.

Electro-Hydraulic Valve Actuators (EHVAs) are proposed as an enabling technology for implementation of advanced combustion concepts via Variable Valve Actuation (VVA) of intake and exhaust valves separately, with benefits of pollution reduction and improvement of efficiency for internal combustion engines. In this regard, the mathematical modelling of an EHVA system for camless engines is tackled in this report. The system complexity, nonlinear properties and time delay phenomena of the hydraulic actuator make the modeling, identification and control challenging. Model parameters are estimated via an off-line parameter identification procedure which combines least square method, regression model and nonlinear optimization routines. The combined approach is applied to a wide set of experimental data. The resulting model aims to predict system dynamics and be exploited for synthesizing cycle-by-cycle control algorithms for valve lift.

Over the last few years, theoretical and modelling studies have been carried out on the feasibility and potential of novel mild air hybrid engine concepts based on production components. These mild air hybrid concepts are able to convert vehicle brake energy into pneumatic energy in the form of compressed air stored in the air tank. The compressed air can then be used to crank-start the engine by either injecting and expanding in the cylinder or driving a production air starter. Thus, the regenerative stop–start operation can be readily realised for improved fuel economy. In order to demonstrate air hybrid engine charging operation experimentally and validate the theoretical analysis, a single-cylinder engine has been adapted to operate in the compressor mode with the novel one-way intake system. Two air intake designs were implemented and tested so that their ability to capture compressed air could be analysed. In particular, it is shown that the compressor mode can be accomplished effectively through a simple cam profile switching device which has been used in production engines. Furthermore, the experimental and analytical results show a good agreement which gives high confidence to the theoretical analyses carried out on different mild air hybrid engine concepts examined.

A type of Electro-Mechanical Valve Actuator (EMVA) formed by two opposed electromagnets and two balanced springs has been widely studied in literature in the last decade since it seems to be a promising solution for implementing advanced engine combustion concepts based on VVA (Variable Valve Actuation) systems. In fact, their use can increase engine power, reduce fuel consumption and pollutant emissions, improving significantly engine efficiency. Nevertheless, strongly nonlinear behavior characterizing these actuators coupled to variations of plant parameters and external forces as well make the control problems very challenging. In this regard, we focussed the attention on the Soft Landing Control (SLC) guaranteeing a soft approach of the engine valve to its valve seat with limited impact velocities. In this report, a cycle-by-cycle control algorithm is proposed to reduce the landing velocity of the valve against its seat. The idea is to modify a preexisting Sliding Mode Controller (SMC) adding a further control action which is updated at each engine cycle. The extra control action is obtained by exploiting the gradient descent method to derive a control algorithm that allows always to reach the minimum impact velocity despite. The effectiveness of the cycle-by-cycle adaptation strategy is validated in a high predictive numerical simulator of the EMVA system when considering perturbed scenarios.

A type of Electro-Mechanical Valve Actuator (EMVA) formed by two opposed electromagnets and two balanced springs has been widely studied in literature in the last decade since it seems to be a promising solution for implementing advanced engine combustion concepts based on VVA (Variable Valve Actuation) systems. In fact, their use can increase engine power, reduce fuel consumption and pollutant emissions, improving significantly engine efficiency Nevertheless, strongly nonlinear behavior characterizing these actuators coupled to variations of plant parameters and external forces as well make the control problems very challenging. Among other, we have focussed the attention on the Soft Landing Control (SLC) guaranteeing a soft approach of the engine valve to its valve seat with limited impact velocities. In this report, the results of a numerical study aimed for making more robust a pre-existing closed-loop SLC strategy are presented. Different force compensations approaches are explored and the analysis is done in the basis of a nonlinear map that characterizes the system output (i.e. seating velocity) with respect to an adimensional gain under study. The idea behind our approach is to identify a new control knob that an external cycle-by-cycle control adaption law uses to reduce valve seating velocities. Finally, a PI-based cycle-by-cycle learning algorithm is proposed to show the effectiveness of the compensation approach via numerical simulations.

Modern VVA systems offer new potentialities in improving fuel consumption for spark-ignition engines at low and medium load, meanwhile they grant a higher volumetric efficiency and performance at high load. Recently introduced systems enhance this concept through the possibility of modifying the intake valve opening, closing and lift, leading to the development of almost ‘throttle-less’ engines. However, at low loads, the absence of throttling, while improving the fuel consumption, also produces an increased gas-dynamic noise at the intake mouth. Wave propagation inside the intake system is in fact no longer absorbed by the throttle valve and directly impact the radiated noise. In the paper, 1D and 3D simulations of the gas-dynamic noise radiated by a production VVA engine are performed at full load and in two part-load conditions. Both models are firstly validated at full load, through comparisons with experimental data. Different settings of the VVA device at part-load are moreover considered to quantify the trade-off existing between fuel consumption and radiated noise reduction. The analyses put into evidence that the optimal control strategy for fuel consumption improvement does not allow a satisfactory abatement of the radiated noise, as well. Presented results show that, at low engine speed, the VVA setting realizing the lowest fuel consumption also produces an acceptable overall noise level. On the contrary, a small fuel consumption penalty must be paid at medium speed to realize a sufficiently low radiated noise. The proposed 1D-3D procedure hence constitutes a very useful tool to realize a fully-numerical pre-calibration of the engine under development.

A type of Electro-Mechanical Valve Actuator (EMVA) formed by two opposed electromagnets and two balanced springs has been widely studied in literature in the last decade since it seems to be a promising solution for implementing advanced engine combustion concepts based on VVA (Variable Valve Actuation) systems. In fact, their use can increase engine power, reduce fuel consumption and pollutant emissions, improving significantly engine efficiency. Nevertheless, strongly nonlinear behavior characterizing these actuators coupled to variations of plant parameters and external forces as well make the control problems very challenging. In this regard, we focussed the attention on the Soft Landing Control (SLC) guaranteeing a soft approach of the engine valve to its valve seat with limited impact velocities. In this report, a cycle-by-cycle control algorithm is proposed to reduce the landing velocity of the valve against its seat. The idea is to modify a preexisting Sliding Mode Controller (SMC) adding a further control action which is updated at each engine cycle. The extra control action is computed by using DMCSI control (Discrete Minimal Control Synthesis with Integral) recently appeared in the technical literature. The effectiveness of the entire control scheme is shown via numerical simulations when considering perturbed scenarios.