Hydrogen as carbon-free fuel is a very promising candidate for climate-neutral internal combustion engine operation. In comparison to other renewable fuels, hydrogen does obviously not produce CO2 ...emissions. In this work, two concepts of hydrogen internal combustion engines (H2-ICEs) are investigated experimentally. One approach is the modification of a state-of-the-art gasoline passenger car engine using hydrogen direct injection. It targets gasoline-like specific power output by mixture enrichment down to stoichiometric operation. Another approach is to use a heavy-duty diesel engine equipped with spark ignition and hydrogen port fuel injection. Here, a diesel-like indicated efficiency is targeted through constant lean-burn operation. The measurement results show that both approaches are applicable. For the gasoline engine-based concept, stoichiometric operation requires a three-way catalyst or a three-way NOX storage catalyst as the primary exhaust gas aftertreatment system. For the diesel engine-based concept, state-of-the-art selective catalytic reduction (SCR) catalysts can be used to reduce the NOx emissions, provided the engine calibration ensures sufficient exhaust gas temperature levels. In conclusion, while H2-ICEs present new challenges for the development of the exhaust gas aftertreatment systems, they are capable to realize zero-impact tailpipe emission operation.
The combination of different propulsion and energy storage systems for hybrid vehicles is changing the focus in the field of powertrain calibration. Shorter time-to-market as well as stricter legal ...requirements regarding the validation of Real Driving Emissions (RDE) require the adaptation of current procedures and the implementation of new technologies in the powertrain development process. In order to achieve highest efficiencies and lowest pollutant emissions at the same time, the layout and calibration of the control strategies for the powertrain and the exhaust gas aftertreatment system must be precisely matched. An optimal operating strategy must take into account possible trade-offs in fuel consumption and emission levels, both under highly dynamic engine operation and under extended environmental operating conditions. To achieve this with a high degree of statistical certainty, the combination of advanced methods and the use of virtual test benches offers significant potential. An approach for such a combination is presented in this paper. Together with a Hardware-in-the-Loop (HiL) test bench, the novel methodology enables a targeted calibration process, specifically designed to address calibration challenges of hybridized powertrains. Virtual tests executed on a HiL test bench are used to efficiently generate data characterizing the behavior of the system under various conditions with a statistically based evaluation identifying white spots in measurement data, used for calibration and emission validation. In addition, critical sequences are identified in terms of emission intensity, fuel consumption or component conditions. Dedicated test scenarios are generated and applied on the HiL test bench, which take into account the state of the system and are adjusted depending on it. The example of one emission calibration use case is used to illustrate the benefits of using a HiL platform, which achieves approximately 20% reduction in calibration time by only showing differences of less than 2% for fuel consumption and emission levels compared to real vehicle tests.
Reducing air pollution caused by emissions from road traffic, especially in urban areas, is an important goal of legislators and the automotive industry. The introduction of so-called “Real Driving ...Emission” (RDE) tests for the homologation of vehicles with internal combustion engines according to the EU6d legislation was a fundamental milestone for vehicle and powertrain development. Due to the introduction of non-reproducible on-road emission tests with “Portable Emission Measurement Systems” (PEMS) in addition to the standardized emission tests on chassis dynamometers, emission aftertreatment development and validation has become significantly more complex. For explicit proof of compliance with the emission and fuel consumption regulations, the legislators continue to require the “Worldwide Harmonized Light Duty Vehicle Test Cycle” (WLTC) on a chassis dynamometer. For calibration purposes, also various RDE profiles are conducted on the chassis dynamometer. However, the combination of precisely defined driving profiles on the chassis dynamometer and the dynamics-limiting boundary conditions in PEMS tests on the road still lead to discrepancies between the certified test results and the real vehicle behavior. The expected future emissions standards to replace EU6d will therefore force even more realistic RDE tests. This is to be achieved by significantly extending the permissible RDE test boundary conditions, such as giving more weight to the urban section of an RDE test. In addition, the introduction of limit values for previously unregulated pollutants such as nitrogen dioxide (NO2), nitrous oxide (N2O), ammonia (NH3) and formaldehyde (CH2O) is being considered. Furthermore, the particle number (for diameters of solid particles > 10 nm: PN10), the methane (CH4) emissions and emissions of non-methane organic gases (NMOG) shall be limited and must be tested. To simplify the test procedure in the long term, the abandonment of predefined chassis dyno emission tests to determine the pollutant emission behavior is under discussion. Against this background, current testing, validation, and development methods are reviewed in this paper. New challenges and necessary adaptations of current approaches are discussed and presented to illustrate the need to consider future regulatory requirements in today’s approaches. Conclusions are drawn and suggestions for a robust RDE validation procedure are formulated.
Organ preservation after a clinical complete response to radiochemotherapy is currently one of the most discussed topics in the management of rectal cancer. However, the patients' perspective has ...only been poorly studied so far. In this multicenter study, we examined 49 patients with locally advanced rectal cancer. The willingness to participate in an organ preservation study and the acceptance of the associated aspects such as intensified radiochemotherapy protocols, the need for close follow-up examinations and local regrowth rates were assessed. Attitudes were correlated with baseline quality of life parameters and psychological scales for "fear of progression", "locus of control", "depression", and the "willingness to take risks". A total of 83% of patients would consider the deferral of surgery in case of a clinical complete response (cCR). Three monthly follow-up studies and a 25% local regrowth rate are considered acceptable by 95% and 94% respectively. While 41% would be willing to exchange cure rates for a non-operative treatment strategy, a potentially more toxic radiochemotherapy in order to increase the probability of a cCR was the aspect with the lowest acceptance (55%). Psychological factors, in particular "locus of control" and "willingness to take risks", influenced patient preferences regarding most of the assessed parameters. While in general a broad acceptance of an organ-preserving treatment can be expected, patient preferences and concerns regarding different aspects of this strategy vary widely and require specific consideration during shared decision making.
In view of the deliberations on new Euro 7 emission standards to be introduced by 2025, original equipment manufacturers (OEMs) are already hard at work to further minimise the pollutant emissions of ...their vehicles. A particular challenge in this context will be compliance with new particulate number (PN) limits. It is expected that these will be tightened significantly, especially by including particulates down to 10 nm. This will lead to a substantially increased effort in the calibration of gasoline particulate filter (GPF) control systems. Therefore, it is of great interest to implement advanced methods that enable shortened and at the same time more accurate GPF calibration techniques. In this context, this study presents an innovative GPF calibration procedure that can enable a uniquely efficient development process. In doing so, some calibration work packages involving GPF soot loading and regeneration are transferred to a modern burner test bench. This approach can minimise the costly and time-consuming use of engine test benches for GPF calibration tasks. Accurate characterisation of the particulate emissions produced after a cold start by the target engine in terms of size distribution, morphology, and the following exhaust gas backpressure and burn-off rates of the soot inside the GPF provides the basis for a precise reproduction and validation process on the burner test bench. The burner test bench presented enables the generation of particulates with a geometric mean diameter (GMD) of 35 nm, exactly as they were measured in the exhaust gas of the engine. The elemental composition of the burner particulates also shows strong similarities to the particulates produced by the gasoline engine, which is further confirmed by matching burn-off rates. Furthermore, the exhaust backpressure behaviour can accurately be reproduced over the entire loading range of the GPF. By shifting GPF-related calibration tasks to the burner test bench, total filter loading times can be reduced by up to 93%.
To evaluate the effectiveness of fractionated stereotactic radiotherapy (SFRT) in the treatment of optic nerve sheath meningioma (ONSM).
Between 1993 and 2005, 109 patients (113 eyes) with primary (n ...= 37) or secondary (n = 76) ONSM were treated according to a prospective protocol with SFRT to a median dose of 54 Gy. All patients underwent radiographic, ophthalmologic, and endocrine analysis before and after SFRT. Radiographic response, visual control, and late side effects were endpoints of the analysis.
Median time to last clinical, radiographic, and ophthalmologic follow up was 30.2 months (n = 113), 42.7 months (n = 108), and 53.7 months (n = 91), respectively. Regression of the tumor was observed in 5 eyes and progression in 4 eyes, whereas 104 remained stable. Visual acuity improved in 12, deteriorated in 11, and remained stable in 68 eyes. Mean visual field defects reduced from 33.6% (n = 90) to 17.8% (n = 56) in ipsilateral and from 10% (n = 94) to 6.7% (n = 62) in contralateral eyes. Ocular motility improved in 23, remained stable in 65, and deteriorated in 3 eyes. Radiographic tumor control was 100% at 3 years and 98% at 5 years. Visual acuity was preserved in 94.8% after 3 years and in 90.9% after 5 years. Endocrine function was normal in 90.8% after 3 years and in 81.3% after 5 years.
SFRT represents a highly effective treatment for ONSM. Interdisciplinary counseling of the patients is recommended. Because of the high rate of preservation of visual acuity we consider SFRT the standard approach for the treatment of ONSM. Prolonged observation is warranted to more accurately assess late visual impairment. Moderate de-escalation of the radiation dose might improve the preservation of visual acuity and pituitary gland function.
Further reducing greenhouse gas and pollutant emissions from road vehicles is a major task for the automotive industry. Stricter regulations regarding emissions and fleet fuel consumption require the ...continuous development of new powertrains and methods. In particular, the combination of hybrid powertrains on the technical side and the focus on real driving emissions (RDE) on the legislative side pose significant challenges to the vehicle calibration process. Against this background, new test methods and environments are being investigated to counteract the high number of interactions between hybrid drive systems and quasi-infinite test conditions due to RDE. Complementary to new test environments, innovative methods for data analysis are needed that allow the exploitation of the complete potential of measurement data. The application of such a method in the field of emission calibration is presented in this paper. For this purpose, a clustering method (HDBSCAN) is applied to critical sequences from emission tests. Within this presentation, the clustering process is based on a single signal only. This paper shows how signals of various characteristics can be processed with dynamic time warping and generically structured with the clustering method used. Here, 959 single events are automatically categorized into 24 clusters. This provides a new basis for system evaluation, enabling the automatic identification, categorization, and prioritization of calibration weaknesses. Using twelve signals of different characteristics, the generic usability of the clustering method is demonstrated.
Gasoline particulate filters (GPF) recently entered the market and are already regarded as state-of-the-art for gasoline exhaust aftertreatment systems to enable EU6d-TEMP fulfillment and beyond. Due ...to its rapid market introduction, the field of GPF lifetime evaluation is still open for research. In this context, the paper describes the advantages of a method for accelerated investigation of filter ash loading during the development of particulate filters. The central task is the simulation of real-world lubrication oil consumption and combustion, which is the major source of ash in the exhaust gases. For that purpose, a burner test bench designed for catalyst aging was additionally equipped with an oil injection unit. The injection unit enables control of the oil volume and the droplet sizes as precursors for the ash particulates. The results obtained with the new filter aging method are compared with data from vehicle endurance runs and with burner test investigations in which the fuel is doped with oil. The latter method is currently considered as the state-of-the-art method for accelerated ash generation. The new method proofed to be vehicle-equivalent in terms of ash-induced backpressure, filtration efficiency, wall ash layer formation, and wall/plug ash ratio. In this context, it turned out that it is important not to atomize the oil droplets too far, since smallest particulates accumulate mainly at the walls and cause unrealistically high backpressures. Furthermore, the ash loading process should include different mass flows in order to achieve stable backpressure results.
Purpose:
The purpose of this study was to analyze the probability and time course of fibrotic changes in breast reconstruction before or after postmastectomy radiotherapy (PMRT).
Materials and ...Methods:
Between 1995 and 2004, 109 patients were treated with PMRT at Tübingen University and underwent heterologous (HL) or autologous (AL) breast reconstruction prior or subsequent to radiation therapy. Fibrosis of the reconstructed breast after radiotherapy was assessed using the Baker score for HL reconstructions and the Common Terminology Criteria for Adverse Events (CTCAE) for all patients. Actuarial rates of fibrosis were calculated for the maximum degree acquired during follow- up and at the last follow-up visit documented.
Results:
Median time to follow-up was 34 months (3–227 months). Radiotherapy was applied with a median total dose of 50.4 Gy. A total of 44 patients (40.4%) received a boost treatment with a median dose of 10 Gy. Breast reconstruction was performed with AL, HL, or combined techniques in 20, 82, and 7 patients, respectively. The 3-year incidence of ¡Ý grade III maximum fibrosis was 20% and 43% for Baker and CTCAE scores, respectively. The corresponding figures for fibrosis at last follow-up visit were 18% and 2%. The 3-year rate of surgical correction of the contralateral breast was 30%. Initially unplanned surgery of the reconstructed breast was performed in 39 patients (35.8%). Boost treatment and type of cosmetic surgery (HL vs. AL) were not significantly associated with the incidence of fibrosis.
Conclusions:
We found severe fibrosis to be a frequent complication after PMRT radiotherapy and breast reconstruction. However, surgical intervention can ameliorate the majority of high grade fibrotic events leading to acceptable long-term results. No treatment parameters associated with the rate of fibrosis could be identified.
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