| 1. |
- Amini, Hashem, et al.
(författare)
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Comparison of ultrasound and autopsy findings in pregnancies terminated due to fetal anomalies
- 2006
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : Wiley. - 0001-6349 .- 1600-0412. ; 85:10, s. 1208-1216
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To compare antenatal diagnoses with autopsy findings in pregnancies terminated after ultrasound detection of fetal anomalies. A second aim was to study the quality of antenatal fetal diagnosis over time. Design. Retrospective, multicenter study over two consecutive six-year periods in Uppsala and Stockholm. Setting. Cases were identified through fetal autopsy reports. Subjects. Three hundred and twenty-eight fetuses from pregnancies terminated between 1992 and 2003 because of ultrasonographically diagnosed anomalies. Main outcome measures. The findings at the last ultrasound examination were compared with the autopsy reports. Results. In 299 cases (91.2%) ultrasound findings either exactly matched or were essentially similar to the autopsy findings. In 23 cases (7%) ultrasound findings were not confirmed at autopsy, but the postnatal findings were at least as severe as the antenatal ones. In six cases (1.8%) termination was performed for an anomaly which proved to be less severe than was predicted by ultrasound. The number of such cases was the same in both six-year periods, while the total number of cases increased from 113 in the first to 215 in the second period. Fetal examination provided further diagnostic information in 47% of the cases. In 10% a syndrome was disclosed. Conclusion. Termination of pregnancy was not always based on a correct antenatal diagnosis. All fetuses but one from terminated pregnancies had evident anomalies. In six cases (1.8%) the decision to terminate was based on suboptimal prognostic and diagnostic information. Fetal autopsy by an experienced perinatal pathologist is essential to provide a definitive diagnosis.
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| 2. |
- Baer, Katharina, 1984-, et al.
(författare)
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Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design
- 2016
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Ingår i: Proceedings of the 9th FPNI Ph.D. Symposium on Fluid Power (FPNI2016). - : American Society of Mechanical Engineers. - 9780791850473
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Konferensbidrag (refereegranskat)abstract
- Hybridization of a vehicle’s drivetrain can in principle help to improve its energy efficiency by allowing for recuperation of kinetic energy and modulating the engine’s load. How well this can be realized depends on appropriate sizing and control of the additional components. The system is typically designed sequentially, with the hardware setup preceding the development and tuning of advanced controller architectures. Taking an alternative approach, component sizing and controller tuning can be addressed simultaneously through simulation-based optimization.The results of such optimizations, especially with standard algorithms with continuous design variable ranges, can however be difficult to realize, considering for example limitations in available components. Furthermore, drive-cycle based optimizations are prone to cycle-beating. This paper examines the results of such simulation-based optimization for a series hydraulic hybrid vehicle in terms of sensitivity to variations in design parameters, system parameters and drive cycle variations. Additional relevant aspects concerning the definition of the optimization problem are pointed out.
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| 3. |
- Baer, Katharina, et al.
(författare)
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Component Sizing Study for a Light-Duty Series Hydraulic Hybrid Vehicle in Urban Drive Cycles
- 2013
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Konferensbidrag (refereegranskat)abstract
- With the focus on energy efficiency for many different kinds of vehicle applications,hybridization is considered a possible solution to reduce fuel consumption. While hybrid electric concepts are already available for passenger vehicles, and also considered for heavier applications, hybrid hydraulic alternatives have been mainly limited to the latter, which benefit most from the higher power density available. To study the different hybrid architectures and applications, a modeling framework for the system design is developed using the simulation tool Hopsan from Linköping University. Previously, the model of a series hydraulic hybrid vehicle was introduced, a light-duty vehicle simulated over two standard urban drive cycles, and its potential for further work established. In this paper, the model is extended by including a simple combustion engine power management to provide for more realistic propulsion of the hydraulic drivetrain, showing the potential to operate a series hydraulic hybrid vehicle’s engine in more efficient regions. Additionally, the design is studied concerning the effects of a variation of key component sizes on the accuracy and energy efficiency objectives. Instead of subjecting the system to (multi- objective) optimization, at this stage the individual component’s influence is studied, and the objectives are dealt with separately from each other to eliminate the need for compromise between them, both to gain a better understanding of the interdependencies.
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| 4. |
- Baer, Katharina, et al.
(författare)
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Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle
- 2015
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Konferensbidrag (refereegranskat)abstract
- Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.
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| 5. |
- Baer, Katharina, 1984-, et al.
(författare)
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Framework for simulation-based simultaneous system optimization for a series hydraulic hybrid vehicle
- 2019
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Ingår i: International Journal of Fluid Power. - : Taylor & Francis. - 1439-9776 .- 2332-1180. ; 20:1, s. 27-51
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Tidskriftsartikel (refereegranskat)abstract
- Hybridisation of hydraulic drivetrains offers the potential of efficiency improvement for on – and off-road applications. To realise the advantages, a carefully designed system and corresponding control strategy are required, which are commonly obtained through a sequential design process. Addressing component selection and control parameterisation simultaneously through simulation-based optimisation allows for exploration of a large design space as well as design relations and trade-offs, and their evaluation in dynamic conditions which exist in real driving scenarios. In this paper, the optimisation framework for a hydraulic hybrid vehicle is introduced, including the simulation model for a series hybrid architecture and component scaling considerations impacting the system’s performance. A number of optimisation experiments for an on-road light-duty vehicle, focused on standard-drive-cycle-performance, illustrate the impact of the problem formulation on the final design and thus the complexity of the design problem. The designs found demonstrate both the potential of energy storage in series hybrids, via an energy balance diagram, as well as some challenges. The framework presented here provides a base for systematic evaluation of design alternatives and problem formulation aspects.
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| 6. |
- Baer, Katharina, et al.
(författare)
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Modeling of a Series Hybrid Hydraulic Drivetrain for a Light-Duty Vehicle in Hopsan
- 2013
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Ingår i: Conference proceedings. - Linköping, Sweden : Linköping University Electronic Press. - 9789175195728 ; , s. 107-112
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Konferensbidrag (refereegranskat)abstract
- Hydraulic hybrids continue to receive attention as a possible solution in the search for improved fuel economy for different vehicle types. This paper presents a model for a series hydraulic hybrid light-duty vehicle, developed in the Hopsan simulation tool of Linköping University’s Division of Fluid and Mechatronic Systems (Flumes). Focusing on the hydraulic transmission which employs a pump control based on the hydraulic accumulator’s state-of-charge (SoC), several simplifications were made, especially concerning mechanical components. Simulation over two urban standard cycles shows promising results concerning dynamic performance and energy recuperation potential, provided sufficient component sizing to compensate for the mechanical limitations. This paper lays the foundation for both a further refined model - suitable for optimizing the full drivetrain, including component sizing and controller parameterization - and the development of comparable models for parallel and power-split hybrid architectures.
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| 7. |
- Baer, Katharina, 1984-, et al.
(författare)
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Robustness and performance evaluations for simulation-based control and component parameter optimization for a series hydraulic hybrid vehicle
- 2020
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Ingår i: Engineering optimization (Print). - : Taylor & Francis. - 0305-215X .- 1029-0273. ; 52:3, s. 446-464
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Tidskriftsartikel (refereegranskat)abstract
- Simulation-based optimization is a useful tool in the design of complex engineering products. Simulation models are used to capture numerous aspects of the design problem for the objective function. Optimization results obtained can be assessed from various perspectives. In this study, component and control optimization of a series hydraulic hybrid vehicle is used as an application, and different robustness and performance aspects are evaluated. Owing to relatively high computational loads, efficient optimization algorithms are important to provide sufficient quality of results at reasonable computational costs. To estimate problem complexity and evaluate optimization algorithm performance, the definitions for information entropy and the related performance index are extended. The insights gained from various simulation-based optimization experiments and their subsequent analysis help characterize the efficiency of the optimization problem formulation and parameterization, as well as optimization algorithm selection with respect to parallel computation capabilities for further development of the model and optimization framework.
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| 8. |
- Baer, Katharina, 1984-
(författare)
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Simulation-Based Optimization of a Series Hydraulic Hybrid Vehicle
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hybrid transmissions are characterized by their utilization of more than one form of energy storage. They have the potential to help reduce overall fuel consumption and vehicle emissions by providing the possibility of brake energy recuperation and prime mover operation management. Electric hybrids and electric vehicle drives are nowadays ubiquitous, and mechanical energy storage in flywheel has been investigated in the past. The use of fluid power technology with a combustion engine has also been investigated since the late 1970s, and is frequently revisited.Hydraulic hybridization is especially attractive for heavy vehicles with frequent braking and acceleration which benefit most from fluid power components’ high power density, typically busses, delivery or refuse vehicles, and vehicles with existing hydraulic circuits and transmissions, such as forest and construction machinery, but have been considered for smaller vehicles as well.Due to the characteristic discharge profile of hydraulic energy storage, special attention needs to be paid to control aspects in the design process to guarantee drivability of the vehicle. In this respect, simulation models can be of use in early design process stages for cheaper and faster evaluation of concepts and designs than physical experiments and prototyping, and to generate better understanding of the system studied. Engineering optimization aids in the systematic exploration of a given design space, to determine limits and potentials, evaluate trade-offs and potentially find unexpected solutions. In the optimization of a hydraulic hybrid transmission, the integration of component and controller design is of importance, and different strategies (sequential, iterative, bi-level and simultaneous approaches) are conceivable, with varying consequences for the implementation.This thesis establishes a simulation-based optimization framework for a hydraulic hybrid transmission with series architecture. Component and control parameter optimization are addressed simultaneously, using a rule-based supervisory control strategy. The forward-facing dynamic simulation model at the centre of the framework is built in Hopsan, a multi-disciplinary open-source tool developed at Linköping University. The optimization is set up and conducted for an example application of an on-road light-duty truck over standard drive cycles. Both results from these experiments as well as the framework itself are studied and evaluated. Relevant design aspects, such as explicit design relations to be considered and performance requirements for more robust design, are identified and addressed, and the optimization problem is analysed with regard to algorithm performance and problem formulation. The final result is an optimization framework that can be adjusted for further in-depth studies, for example through the inclusion of additional components or optimization objectives, and extendable for comparative analysis of different topologies, applications and problem formulations.
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| 9. |
- Baer, Katharina, et al.
(författare)
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System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle
- 2014
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Ingår i: PROCEEDINGS OF THE 8TH FPNI PH.D SYMPOSIUM ON FLUID POWER, 2014. - : ASME Press. - 9780791845820 ; , s. V001T03A004-
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Konferensbidrag (refereegranskat)abstract
- Amongst the hybrid vehicle propulsion solutions aiming to improve fuel efficiency, hybrid electric solutions currently receive most attention, especially on the market. However, hydraulic hybrids are an interesting alternative, especially for heavier vehicles due to higher power density which is beneficial if higher masses are moved. As a step towards a comprehensive design framework to compare several possible hydraulic hybrid architectures for a specified application and usage profile, the model of a series hydraulic hybrid vehicle was previously introduced and initially studied concerning component sizing for an exemplary light-duty vehicle in urban traffic. The vehicle is modeled in the Hopsan simulation tool. A comparably straight-forward engine management is used for the vehicle control; both pump and engine controls are based on the hydraulic accumulator’s state-of-charge. The model is developed further with respect to the accumulator component model. Based on that, the influence of several system and component parameters, such as maximum system pressure and engine characteristics, as well as controller parameters on the vehicle’s performance is analyzed. The goal is to allow for more understanding of the system’s characteristics to facilitate future optimization of the system.
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| 10. |
- Bondeson, Marie-Louise, 1960-, et al.
(författare)
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A nonsense mutation in CEP55 defines a new locus for a Meckel-like syndrome, an autosomal recessive lethal fetal ciliopathy.
- 2017
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Ingår i: Clinical Genetics. - : Wiley. - 0009-9163 .- 1399-0004. ; 92:5, s. 510-516
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in genes involved in the cilium-centrosome complex are called ciliopathies. Meckel-Gruber syndrome (MKS) is a ciliopathic lethal autosomal recessive syndrome characterized by genetically and clinically heterogeneous manifestations, including renal cystic dysplasia, occipital encephalocele and polydactyly. Several genes have previously been associated with MKS and MKS-like phenotypes, but there are still genes remaining to be discovered. We have used whole exome sequencing (WES) to uncover the genetics of a suspected autosomal recessive Meckel syndrome phenotype in a family with two affected fetuses. RNA studies and histopathological analysis was performed for further delineation. WES lead to identification of a homozygous nonsense mutation c.256C>T (p.Arg86*) in CEP55 (centrosomal protein of 55 kDa) in the affected fetus. The variant has previously been identified in carriers in low frequencies, and segregated in the family. CEP55 is an important centrosomal protein required for the mid-body formation at cytokinesis. Our results expand the list of centrosomal proteins implicated in human ciliopathies and provide evidence for an essential role of CEP55 during embryogenesis and development of disease.
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