Automotive diesel engine transient operation: modeling, optimization and control

Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive engines is inherently related to unsteady conditions. There are various operating conditions experienced by (diesel) engines that can be classified as transient. Besides the variation of the engine operating point, in terms of engine speed and torque, also the warm up phase can be considered as a transient condition. Chapter 2 has to do with this thermal transient condition; more precisely the main issue is the performance of a Selective Catalytic Reduction (SCR) system during cold start and warm up phases of the engine. The proposal of the underlying work is to investigate and identify optimal exhaust line heating strategies, to provide a fast activation of the catalytic reactions on SCR. Chapters 3 and 4 focus the attention on the dynamic behavior of the engine, when considering typical driving conditions. The common approach to dynamic optimization involves the solution of a single optimal-control problem. However, this approach requires the availability of models that are valid throughout the whole engine operating range and actuator ranges. In addition, the result of the optimization is meaningful only if the model is very accurate. Chapter 3 proposes a methodology to circumvent those demanding requirements: an iteration between transient measurements to refine a purpose-built model and a dynamic optimization which is constrained to the model validity region. Moreover all numerical methods required to implement this procedure are presented. Chapter 4 proposes an approach to derive a transient feedforward control system in an automated way. It relies on optimal control theory to solve a dynamic optimization problem for fast transients. From the optimal solutions, the relevant information is extracted and stored in maps spanned by the engine speed and the torque gradient.

Simulazione dinamica di un veicolo dotato di powertrain ibrido endotermico-elettrico

Nel panorama motoristico ed automobilistico moderno lo sviluppo di motori a combustione interna e veicoli è fortemente influenzato da diverse esigenze che spesso sono in contrasto le une con le altre. Infatti gli obiettivi di economicità e riduzione dei costi riguardanti la produzione e la commercializzazione dei prodotti sono in contrasto con gli sforzi che devono essere operati dalle case produttrici per soddisfare le sempre più stringenti normative riguardanti le emissioni inquinanti ed i consumi di carburante dei veicoli. Fra le numerose soluzioni presenti i veicoli ibridi rappresentano una alternativa che allo stato attuale è già presente sul mercato in varie forme, a seconda della tipologie di energie accoppiate. In letteratura è possibile trovare numerosi studi che trattano l’ottimizzazione dei componenti o delle strategie di controllo di queste tipologie di veicoli: in moltissimi casi l’obiettivo è quello di minimizzare consumi ed emissioni inquinanti. Normalmente non viene posta particolare attenzione agli effetti che l’aggiunta delle macchine elettriche e dei componenti necessari per il funzionamento delle stesse hanno sulla dinamica del veicolo. Il presente lavoro di tesi è incentrato su questi aspetti: si è considerata la tipologia di veicoli ibridi termici-elettrici di tipo parallelo andando ad analizzare come cambiasse il comportamento dinamico del veicolo in funzione del tipo di installazione considerato per la parte elettrica del powertrain. In primo luogo è stato quindi necessario costruire ed implementare un modello dinamico di veicolo che permettesse di applicare coppie alle quattro ruote in maniera indipendente per considerare diverse tipologie di powertrain. In seguito si sono analizzate le differenze di comportamento dinamico fra il veicolo considerato e l’equivalente versione ibrida e i possibili utilizzi delle macchine elettriche per correggere eventuali deterioramenti o cambiamenti indesiderati nelle prestazioni del veicolo.

57 Fe and 119 Sn Mössbauer studies on new Heusler compounds for spintronic applications

Seit der Entwicklung einer großen Vielfalt von Anwendungsmöglichkeiten der Spintronik auf Basis von Heusler Verbindungen innerhalb der letzten Dekade kann der Forschungsfortschritt an dieser Material Klasse in einer Vielzahl von Publikationen verfolgt werden. Eine typische Heusler Verbindung X2YZ besteht aus zwei Übergangsmetallen (X, Y) und einem Hauptgruppenelement (Z). Diese Arbeit berichtet von Heusler Verbindungen mit besonderem Augenmerk auf deren potentielle halbmetallische Eigenschaften und davon insbesondere solche, die eine richtungsabhängige magnetische Anisotropie (perpendicular magnetic anisotropy- PMA) zeigen könnten. PMA ist insbesondere für Spin transfer Torque (STT) Bauelemente von großem Interesse und tritt in tetragonalrnverzerrten Heusler Verbindungen auf. Bei STT-Elementen werden mittels spinpolarisierter Ströme die magnetische Orientierung von magnetischen Schichten beeinflusst.rnDie signifikantesten Ergebnisse dieser Arbeit sind: die Synthese neuer kubischen Heusler Phasen Fe2YZ, die theoretisch als tetragonal vorausgesagt wurden (Kapitel 1), die Synthese von Mn2FeGa, das in der tetragonal verzerrten Struktur kristallisiert und Potential für STT Anwendungen zeigt (Kapitel 2); die Synthese von Fe2MnGa, das einen magnetischen Phasenübergang mit exchange-bias (EB) Effekt zeigt, der auf einer Koexistenz von ferromagnetischen (FM) und antiferromagnetischen (AFM) Phasen beruht (Kapitel 3); Schlussendlich wird in Kapitel 4 die Synthese von Mn3−xRhxSn diskutiert, in welcher insbesondere tetragonales Mn2RhSn als potentielles Material für Anwendungen in derrnSpintronik vorgestellt wird.rnIn dieser Arbeit wurden hauptsächlich Heusler Verbindungen mit mößbaueraktiven Elementen 57Fe und 119Sn, synthetisiert und untersucht. Im Falle der hier untersuchten Heusler Verbindungen spielt die Charakterisierung durch Mößbauer Spektroskopie eine entscheidende Rolle, da Heusler Verbindungen meistens ein gewisses Maß an Fehlordnung aufweisen, welche deren magnetischen und strukturellen Eigenschaften beeinflussen kann. Die Art der Fehlordnung jedoch kann nur schwer durch standard Pulver-Röntgendiffraktion bestimmt werden, weshalb wir die Vorteile der Mößbauer Spektroskopie als lokale Methode nutzen, um den Typ und den Grad der Fehlordnung aufzuklären. rnDiese Arbeit ist wie folgt gegliedert:rnIn Kapitel 1 wurden die neuen, kubisch-weichferromagnetischen Heuslerphasen Fe2NiGe, Fe2CuGa und Fe2CuAl synthetisiert und charakterisiert. In vorangegangenen theoretischen Studien wurde für deren Existenz in tetragonaler Heuslerstruktur vorhergesagt.rnUngeachtet dessen belegten unsere experimentellen Untersuchungen, dass diese Verbindungen hauptsächlich in der kubischen invers Heusler(X-) struktur mit unterschiedlichen Anteilen an atomarer Fehlordnung kristallisieren. Alle Verbindungen sind weiche Ferromagneten mit hoher Curietemperatur bis zu 900K, weswegen alle als potentielle Materialien für magnetische Anwendungen geeignet sind. In Kapitel 2 wurde Mn2FeGa synthetisiert. Es zeigte sich, dass Mn2FeGa nach Temperatur Nachbehandlung bei 400°C die invers tetragonale Struktur (I4m2) annimmt. Theoretisch wurde die Existenz in der inversen kubischen Heuslerstruktur vorausgesagt. Abhängig von den Synthesebedingungen ändern sich die magnetischen und strukturellen Eigenschaften von Mn2FeGa eklatant. Deshalb ändert sich die Kristallstruktur von M2FeGa bei Temperung bei 800 °C zu einer pseudokubischen Cu3Au-artigen Struktur, in welcher Fe- und Mn-Atome statistisch verteilt vorliegen. Dieser Übergang der Kristallstrukturen wurde durch Mößbauer Spektroskopie anhand des Vorliegens oder Fehlens der Quadrupolaufspaltung im Falle der invers tetragonalen bzw. pseudokubischen Modifikation nachgewiesen. In Kapitel 3 wurde Fe2MnGa ebenfalls erfolgreich synthetisiert und durch verschiedene Methoden charakterisiert. Der Zusammenhang von Kristallstruktur und magnetischen Eigenschaften wurde durch verschiedene Temperungskonditionen und mechanischer Behandlung untersucht. Der Schwerpunkt lag auf einer geschmolzenen Probe ohne weitere Temperung, die einen FM-AFM Phasenübergang zeigte. Diese magnetische Phasenumwandlung führt zu einem starken EB-Verhalten, welches seinen Ursprung hauptsächlich in der Koexistenz von FM- und AFM-Phasen unterhalb der FMAFM- Übergangstemperatur hat. Kapitel 4 ist den neuen Mn-basierten Heusler-Verbindungen Mn3−xRhxSn gewidmet, bei denen wir versuchten, durch den Austausch von Mn durch das größere Rh eine Umwandlung zu einer tetragonalen Struktur von den hexagonalen Mn3Sn-Struktur zu erreichen. Als interessant stellten sich Mn2RhSn und Mn2.1Rh0.9Sn heraus, da sie aus nur einer Phase vorzuliegen scheinen, wohingegen die anderen Verbindungen aus gemischten Phasen mit gleichzeitiger starken Fehlordnung bestehen. Im abschließenden Anhang wurden die Fehlordnung und gelegentliche Mischphasen einer großen Auswahl von Mn3−xFexGa Materialien mit 1≤x≤3, dokumentiert.rn

Field-free control of magnetism in nanostructured materials probed with high resolution X-ray microscopy

Magnetic memories are a backbone of today's digital data storage technology, where the digital information is stored as the magnetic configuration of nanostructured ferromagnetic bits. Currently, the writing of the digital information on the magnetic memory is carried out with the help of magnetic fields. This approach, while viable, is not optimal due to its intrinsically high energy consumption and relatively poor scalability. For this reason, the research for different mechanisms that can be used to manipulate the magnetic configuration of a material is of interest. In this thesis, the control of the magnetization of different nanostructured materials with field-free mechanisms is investigated. The magnetic configuration of these nanostructured materials was imaged directly with high resolution x-ray magnetic microscopy. rnFirst of all, the control of the magnetic configuration of nanostructured ferromagnetic Heusler compounds by fabricating nanostructures with different geometries was analyzed. Here, it was observed that the magnetic configuration of the nanostructured elements is given by the competition of magneto-crystalline and shape anisotropy. By fabricating elements with different geometries, we could alter the point where these two effects equilibrate, allowing for the possibility to tailor the magnetic configuration of these nanostructured elements to the required necessities.rnThen, the control of the magnetic configuration of Ni nanostructures fabricated on top of a piezoelectric material with the magneto-elastic effect (i.e. by applying a piezoelectric strain to the Ni nanostructures) was investigated. Here, the magneto-elastic coupling effect gives rise to an additional anisotropy contribution, proportional to the strain applied to the magnetic material. For this system, a reproducible and reversible control of the magnetic configuration of the nanostructured Ni elements with the application of an electric field across the piezoelectric material was achieved.rnFinally, the control of the magnetic configuration of La0.7Sr0.3MnO3 (LSMO) nanostructures with spin-polarized currents was studied. Here, the spin-transfer torque effect was employed to achieve the displacement of magnetic domain walls in the LSMO nanostructures. A high spin-transfer torque efficiency was observed for LSMO at low temperatures, and a Joule-heating induced hopping of the magnetic domain walls was observed at room temperatures, allowing for the analysis of the energetics of the domain walls in LSMO.rnThe results presented in this thesis give thus an overview on the different field-free approaches that can be used to manipulate and tailor the magnetization configuration of a nanostructured material to the various technological requirements, opening up novel interesting possibilities for these materials.

Mechanical insertion properties of calcium-phosphate implant coatings

Abstract Objectives: To investigate the influence of protein incorporation on the resistance of biomimetic calcium-phosphate coatings to the shear forces that are generated during implant insertion. Materials and Methods: Thirty-eight standard (5 x 13 mm) Osseotite((R)) implants were coated biomimetically with a layer of calcium phosphate, which either lacked or bore a co-precipitated (incorporated) depot of the model protein bovine serum albumin (BSA). The coated implants were inserted into either artificial bone (n=18) or the explanted mandibles of adult pigs (n=12). The former set-up was established for the measurement of torque and of coating losses during the insertion process. The latter set-up was established for the histological and histomorphometric analysis of the fate of the coatings after implantation. Results: BSA-bearing coatings had higher mean torque values than did those that bore no protein depot. During the insertion process, less material was lost from the former than from the latter type of coating. The histological and histomorphometric analysis revealed fragments of material to be sheared off from both types of coating at vulnerable points, namely, at the tips of the threads. The sheared-off fragments were retained within the peri-implant space. Conclusion: The incorporation of a protein into a biomimetically prepared calcium-phosphate coating increases its resistance to the shear forces that are generated during implant insertion. In a clinical setting, the incorporated protein would be an osteogenic agent, whose osteoinductive potential would not be compromised by the shearing off of coating material, and the osteoconductivity of an exposed implant surface would not be less than that of a coated one. To cite this article: Hägi TT, Enggist L, Michel D, Ferguson SJ, Liu Y, Hunziker EB. Mechanical insertion properties of calcium-phosphate implant coatings. Clin. Oral Impl. Res. xx, 2010; 000-000. doi: 10.1111/j.1600-0501.2010.01916.x.

DensiProbe Spine: a novel instrument for intraoperative measurement of bone density in transpedicular screw fixation

STUDY DESIGN.: Cadaver study. OBJECTIVE.: To determine bone strength in vertebrae by measuring peak breakaway torque or indentation force using custom-made pedicle probes. SUMMARY OF BACKGROUND DATA.: Screw performance in dorsal spinal instrumentation is dependent on bone quality of the vertebral body. To date no intraoperative measuring device to validate bone strength is available. Destructive testing may predict bone strength in transpedicular instrumentations in osteoporotic vertebrae. Insertional torque measurements showed varying results. METHODS.: Ten human cadaveric vertebrae were evaluated for bone mineral density (BMD) measurements by quantitative computed tomography. Peak torque and indentation force of custom-made probes as a measure for mechanical bone strength were assessed via a transpedicular approach. The results were correlated to regional BMD and to biomechanical load testing after pedicle screw implementation. RESULTS.: Both methods generated a positive correlation to failure load of the respective vertebrae. The correlation of peak breakaway torque to failure load was r = 0.959 (P = 0.003), therewith distinctly higher than the correlation of indentation force to failure load, which was r = 0.690 (P = 0.040). In predicting regional BMD, measurement of peak torque also performed better than that of indentation force (r = 0.897 [P = 0.002] vs. r = 0.777 [P = 0.017]). CONCLUSION.: Transpedicular measurement of peak breakaway torque is technically feasible and predicts reliable local bone strength and implant failure for dorsal spinal instrumentations in this experimental setting.

Development of a model-based transient calibration process for diesel engine electronic control module tables – Part 2: modelling and optimization

This is the second part of a study investigating a model-based transient calibration process for diesel engines. The first part addressed the data requirements and data processing required for empirical transient emission and torque models. The current work focuses on modelling and optimization. The unexpected result of this investigation is that when trained on transient data, simple regression models perform better than more powerful methods such as neural networks or localized regression. This result has been attributed to extrapolation over data that have estimated rather than measured transient air-handling parameters. The challenges of detecting and preventing extrapolation using statistical methods that work well with steady-state data have been explained. The concept of constraining the distribution of statistical leverage relative to the distribution of the starting solution to prevent extrapolation during the optimization process has been proposed and demonstrated. Separate from the issue of extrapolation is preventing the search from being quasi-static. Second-order linear dynamic constraint models have been proposed to prevent the search from returning solutions that are feasible if each point were run at steady state, but which are unrealistic in a transient sense. Dynamic constraint models translate commanded parameters to actually achieved parameters that then feed into the transient emission and torque models. Combined model inaccuracies have been used to adjust the optimized solutions. To frame the optimization problem within reasonable dimensionality, the coefficients of commanded surfaces that approximate engine tables are adjusted during search iterations, each of which involves simulating the entire transient cycle. The resulting strategy, different from the corresponding manual calibration strategy and resulting in lower emissions and efficiency, is intended to improve rather than replace the manual calibration process.

Model Predictive Control for Vehicle Stabilization at the Limits of Handling

Recent developments in vehicle steering systems offer new opportunities to measure the steering torque and reliably estimate the vehicle sideslip and the tire-road friction coefficient. This paper presents an approach to vehicle stabilization that leverages these estimates to define state boundaries that exclude unstable vehicle dynamics and utilizes a model predictive envelope controller to bound the vehicle motion within this stable region of the state space. This approach provides a large operating region accessible by the driver and smooth interventions at the stability boundaries. Experimental results obtained with a steer-by-wire vehicle and a proof of envelope invariance demonstrate the efficacy of the envelope controller in controlling the vehicle at the limits of handling.

Extra-articular fractures of the proximal phalanges of the fingers: a comparison of 2 methods of functional, conservative treatment

For nonsurgical treatment of fractures of the proximal phalanges of the triphalangeal fingers, different dynamic casts have been described. The main principle behind these casts is advancement and tightening of the extensor hood, caused by a combination of blocking the metacarpophalangeal joints in flexion and actively flexing the proximal interphalangeal joints. In contrast to established treatment protocols using functional forearm casts, the Lucerne cast allows for free mobilization of the wrist joint. The purpose of the current multicenter study was to compare the results of conservative, functional treatment using 2 different methods, either a forearm cast or a Lucerne cast.

980-nm laser lipolysis (LAL): About 674 procedures in 359 patients

Since the first studies by Apfelberg in 1994, laser lipolysis (LAL) has been on the rise. Laser lipolysis leads to reduced operator fatigue, excellent patient tolerance, quick recovery time, as well as the additional benefit of dermal tightening. This article reports a 5-year experience of LAL and underlines the potential evolutions of the technique.

Laser-assisted lipolysis in the treatment of gynecomastia: a prospective study in 28 patients

Gynecomastia is the most common breast pathology. Numerous excisions and liposuction techniques have been described to correct bilateral male breast enlargement. Recently, there has been a shift from the open approach to minimally invasive techniques. This article reports a 5-year experience using laser-assisted lipolysis (LAL) to treat gynecomastia, and describes the surgical technique. Between January 2006 and December 2010, a total of 28 patients with bilateral gynecomastia were treated with LAL. Patients had a mean age of 36.5 years (range 24 to 56 years). LAL was performed with a 980-nm diode laser (continuous emission, 15 W power, 8-12 kJ total energy per breast) after tumescent anesthetic infiltration. The breast was evaluated objectively by two physicians who compared chest circumference and photographs. Patients were also asked to score the results using a visual analogue scale: 75 to 100 (very good), 50-74 (good), 25 to 49 (fair) and 0 to 24 (poor). The postoperative period for all patients was incident-free. After 6 months, 18 patients (64.3%) scored the results as "very good", 6 as "good" (21.4%), 3 as "fair" (10.7%) and 1 "poor" (3.6%). Mean chest circumferences pre- and postoperatively were, respectively, 117.4 ± 11.1 cm and 103.3 ± 7.5 cm (p < 0.001), corresponding to a mean difference of 14.1 cm. Physicians scored the photographs as "very good" in 22 patients (78.6%), as "good" in five patients (17.9%), and as "fair" in one patient (3.6%). LAL in gynecomastia is safe and produces significant effects on fatty tissue, with a reduction in breast volume, together with significant skin tightening. Provided an appropriate amount of energy is delivered by an experienced operator, the results are both significant and consistent.

[Surgical therapy of gynecomastia]

Nowadays surgical intervention is an essential part of the treatment of idiopathic gynecomastia. Choosing the right method is crucial and is based on the current status in the clinical and histological evaluation. Before finalizing the process of choosing a specific method a prior interdisciplinary evaluation of the patient is necessary to ascertain clear indications for a surgical intervention. Liposuction is one of the methods which have become popular in recent years. The advantages are the possible combination with traditional techniques, such as subcutaneous mastectomy or periareolar mastopexy. The main indication is for gynecomastia stage IIa/b and is justifiable due to the reduction in surgical complications and scarring. Furthermore this technique provides an excellent aesthetical outcome for the patient. A total of 162 patients suffering from gynecomastia stages I-III (according to Simon) were surgically treated between 2000 and 2010 and these cases were retrospectively evaluated. The results showed a decline in the use of a T-shaped incision in combination with subcutaneous mastectomy with periareolar tightening compared to an increase in the use of subcutaneous mastectomy in combination with liposuction. The excised tissue should always be sent for histological examination to make sure no malignant cells were present.

Severe complication of a bonded mandibular lingual retainer

Bonding a flexible spiral wire retainer to the lingual surfaces of all 6 anterior mandibular teeth is a commonly used type of retention. Complications are rare but can be serious enough to produce biologic damage. This article presents a serious complication of a lingual flexible spiral wire retainer. Four years after the orthodontic treatment, a 20-year-old man sought treatment for a broken flexible spiral wire retainer. The clinical examination showed about 35° of buccal root torque of that tooth. A cone-beam computed tomography image showed that the root and the apex of the tooth were almost completely out of the bone on its buccal side. Surprisingly, the tooth's vitality was preserved. The tooth was moved back, nearly to its original position; clinically, only a gingival recession remained. Orthodontists and dentists should be aware of possible complications of bonded retainers. Patients should be clearly informed how to detect problems at an early stage.

Immediate restoration of nonsubmerged titanium implants with a sandblasted and acid-etched surface: five-year results of a prospective case series study using clinical and radiographic data

The aim of this study was to evaluate the survival and success rates of immediately restored implants with sandblasted, large-grit, acid-etched (SLA) surfaces over a period of 5 years. Twenty patients (mean age, 47.3 years) received a total of 21 SLA wide-neck implants in healed mandibular first molar sites after initial periodontal treatment. To be included in the study, the implants had to demonstrate primary stability with an insertion torque value of 35 Ncm. A provisional restoration was fabricated chairside and placed on the day of surgery. Definitive cemented restorations were inserted 8 weeks after surgery. Community Periodontal Index of Treatment Needs (CPITN) indices and the radiographic distance between the implant shoulder and the first visible bone-implant contact (DIB) were measured and compared over the study period. The initial mean CPITN was 3.24, and decreased over the study period to 1.43. At the postoperative radiographic examination, the mean DIB was 1.41 mm for the 21 implants, indicating that part of the machined neck of the implants was placed slightly below the osseous crest. The mean DIB value increased to 1.99 mm at the 5-year examination. This increase proved to be statistically significant (P < .0001). Between the baseline and 5-year examinations, the mean bone crest level loss was 0.58 mm. Success and survival rates of the 21 implants after 5 years of function were 100%. This 5-year study confirms that immediate restoration of mandibular molar wide-neck implants with good primary stability, as noted by insertion torque values of at least 35 Ncm, is a safe and predictable procedure.

Evaluation of chemically modified SLA implants (modSLA) biofunctionalized with integrin (RGD)- and heparin (KRSR)-binding peptides

Enhancing osseointegration through surface immobilization of multiple short peptide sequences that mimic extracellular matrix (ECM) proteins, such as arginine-glycine-aspartic acid (RGD) and lysine-arginine-serine-arginine (KRSR), has not yet been extensively explored. Additionally, the effect of biofunctionalizing chemically modified sandblasted and acid-etched surfaces (modSLA) is unknown. The present study evaluated modSLA implant surfaces modified with RGD and KRSR for potentially enhanced effects on bone apposition and interfacial shear strength during early stages of bone regeneration. Two sets of experimental implants were placed in the maxillae of eight miniature pigs, known for their rapid wound healing kinetics: bone chamber implants creating two circular bone defects for histomorphometric analysis on one side and standard thread configuration implants for removal torque testing on the other side. Three different biofunctionalized modSLA surfaces using poly-L-lysine-graft-poly(ethylene glycol) (PLL-g-PEG) as a carrier minimizing nonspecific protein adsorption [(i) 20 pmol cm⁻² KRSR alone (KRSR); or in combination with RGD in two different concentrations; (ii) 0.05 pmol cm⁻² RGD (KRSR/RGD-1); (iii) 1.26 pmol cm⁻² RGD (KRSR/RGD-2)] were compared with (iv) control modSLA. Animals were sacrificed at 2 weeks. Removal torque values (701.48-780.28 N mm), bone-to-implant contact (BIC) (35.22%-41.49%), and new bone fill (28.58%-30.62%) demonstrated no significant differences among treatments. It may be concluded that biofunctionalizing modSLA surfaces with KRSR and RGD derivatives of PLL-g-PEG polymer does not increase BIC, bone fill, or interfacial shear strength.