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Fail-operational behavior of safety-critical software for autonomous driving is essential as there is no driver available as a backup solution. In a failure scenario, safety-critical tasks can be restarted on other available hardware resources. Here, graceful degradation can be used as a cost-efficient solution where hardware resources are redistributed from non-critical to safety-critical tasks at run-time. We allow non-critical tasks to actively use resources that are reserved as a backup for critical tasks, which would be otherwise unused and which are only required in a failure scenario. However, in such a scenario, it is of paramount importance to achieve a predictable timing behavior of safety-critical applications to allow a safe operation. Here, it has to be ensured that even after the restart of safety-critical tasks a guarantee on execution times can be given. In this paper, we propose a graceful degradation approach using composable scheduling. We use our approach to present, for the first time, a performance analysis which is able to analyze timing constraints of fail-operational distributed applications using graceful degradation. Our method can verify that even during a critical Electronic Control Unit failure, there is always a backup solution available which adheres to end-to-end timing constraints. Furthermore, we present a dynamic decentralized mapping procedure which performs constraint solving at run-time using our analytical approach combined with a backtracking algorithm. We evaluate our approach by comparing mapping success rates to state-of-the-art approaches such as active redundancy and an approach based on resource availability. In our experimental setup our graceful degradation approach can fit about double the number of critical applications on the same architecture compared to an active redundancy approach. Combined, our approaches enable, for the first time, a dynamic and fail-operational behavior of gracefully degrading automotive systems with cost-efficient backup solutions for safety-critical applications.

ABSTRACTThe excellent static mechanical properties of solid solution strengthened grades of ferritic ductile iron (SSFDI) are adjusted by elevated silicon contents and undergo a rapid loss above a critical content of about 4.3 wt-% silicon. This phenomenon is attributed to the formation of iron-silicon superstructures that is intensified in particular by the formation of silicon microsegregation. In order to affect silicon microsegregation, the alloying concept of SSFDI has been modified. In the present investigations, an inversion of the silicon microsegregation profile could be achieved by alloying a nodular cast iron melt with 1.2 wt-% aluminium. The results provide a metallurgical tool to shift the silicon embrittlement to higher silicon contents and thus to further enhance the mechanical properties of SSFDI.

The excellent static mechanical properties of solid solution strengthened grades of ferritic ductile iron (SSFDI) are adjusted by elevated silicon contents and undergo a rapid loss above a critical content of about 4.3?wt-% silicon. This phenomenon is attributed to the formation of iron-silicon superstructures that is intensified in particular by the formation of silicon microsegregation. In order to affect silicon microsegregation, the alloying concept of SSFDI has been modified. In the present investigations, an inversion of the silicon microsegregation profile could be achieved by alloying a nodular cast iron melt with 1.2?wt-% aluminium. The results provide a metallurgical tool to shift the silicon embrittlement to higher silicon contents and thus to further enhance the mechanical properties of SSFDI.

High silicon grades of ductile cast iron are known to be highly advantageous in regard to technically relevant properties and economic efficiency. In particular, the outstanding mechanical properties lead to an increasing demand since 2011, the year of incorporation to the EN 1563 standard. However, low impact resistance and spontaneous failure are concerns that limit the application, especially at lower temperatures. Silicon serves as a solid solution strengthener. By the addition of cobalt, aluminum and nickel as additional solid solution strengthener, an improvement in mechanical properties compared to only silicon could be obtained. Previous studies showed that the addition of 1.5 wt.% Ni to an EN-GJS-500-14 grade with 3.8 wt.% Si resulted in a tensile strength of 650 MPa at 15 % elongation. In the present study, silicon was substituted stepwise by nickel and aluminum, simultaneously aiming at the retention of the mechanical properties of the EN-GJS-500-14 grade. By decreasing the silicon content to 3.3 wt.% Si at 1.1 wt.% Ni and 0.2 wt.% Al, EN-500-14 was obtained. Even though, the presence of pearlite in the matrix was observed, this substitution of silicon led to an increase in Charpy-V-notch toughness by 4 Joule at room temperature. For further alloy design of high silicon ductile cast iron for simultaneously substituting silicon and improving the mechanical properties and notch toughness, the restrictions for pearlite formation must be complied.

ABSTRACTSolid solution-strengthened ductile iron (DI) exhibits outstanding mechanical properties due to the high silicon content. The strengthening by silicon addition is limited since additions above 4.3 wt-% lead to embrittlement. For a further improvement of mechanical properties, other alloying elements need to be considered. In the present work, the effect of various copper additions on the microstructure and the mechanical properties of solid solution-strengthened DI were investigated. The results show that no appreciable strengthening can be achieved by copper addition without the formation of pearlite in the matrix. The pearlite content increases considerably for Cu-additions above 0.23 wt-% and is independent of the cooling rate for the cooling conditions analysed.

Solid solution-strengthened ductile iron (DI) exhibits outstanding mechanical properties due to the high silicon content. The strengthening by silicon addition is limited since additions above 4.3?wt-% lead to embrittlement. For a further improvement of mechanical properties, other alloying elements need to be considered. In the present work, the effect of various copper additions on the microstructure and the mechanical properties of solid solution-strengthened DI were investigated. The results show that no appreciable strengthening can be achieved by copper addition without the formation of pearlite in the matrix. The pearlite content increases considerably for Cu-additions above 0.23?wt-% and is independent of the cooling rate for the cooling conditions analysed.

The article looks at the rise in the forest gardening in Sweden as the agroforestry practice and offers information on the Puttmyra forest garden where several shrub species and herbaceous plants are cultivated.

Objectives. We sought to test the hypothesis that late recanalization of infarct-related coronary arteries (IRAs) improves long-term left ventricular (LV) function.

From 1986 to 1990, 172 patients with a median age of 60.5 years (range 20 to 79 years) Received 187 Omnicarbon valves (109 aortic valve replacements, 48 mitral valve replacements, and 15 double valve replacements). Patients were followed-up for a median observation period of 2.5 years (range 4 months to 5.2 years) by clinical and Doppler echocardiographic examination. Follow-up was complete in 98%. Operative mortality (death within 30 days) was 1.7%, and linearized late mortality was 2.6% per patient-year, corresponding to an actuarial survival rate for operative survivors of 89% after 4 years. The overall 4-year postoperative survival was 87% (93% for aortic valve replacement, 77% for mitral valve replacement). Compared with age- and sex-adjusted Swiss death rates, there was an excess mortality of 5% after 4 years. Percentages for freedom from valve-related complications at 4 years are as follows: thromboembolism, 98% (aortic valve replacement, 98%, and mitral valve replacement, 96%); anticoagulant-related hemorrhage, 95%; valve endocarditis, 96%; reoperation, 96%; and permanent valve-related impairment, 99%. The overall 4-year event-free survival was 76% (80% for aortic valve replacement and 69% for mitral valve replacement). New York Heart Association class improved in 88 % of the patients by 1 to 3 grades, and only 3% remained in class III after operation. For the most commonly used aortic valve (23 mm), Doppler echocardiography revealed a peak pressure gradient of 29 ± 10 mm Hg, a fractional shortening/peak pressure gradient ratio of 1.34 ± 0.61, and a performance index of 0.35 ± 0.08. In the most commonly used mitral valve (27 mm), the mean pressure gradient was 4.0 ± 2.1 mm Hg. We conclude that excellent clinical and hemodynamic results can be obtained with the Omnicarbon prosthesis, in both the aortic and mitral positions. (J Thorac Cardiovasc Surg1993;106:599-608)

Doppler echocardiography was used to study the function of bioprosthetic heart valves by noninvasive means in 32 patients aged 29 to 72 years at various postoperative intervals. There were 24 Ionescu-Shiley, four Hancock, and four Carpentier-Edwards prostheses, 19 in the aortic and 13 in the mitral position. Initial studies were performed at a mean of 2.3 years after implantation and were repeated one, two, and three years thereafter. Flow velocities in the mitral orifice, left ventricular outflow tract, and ascending aorta, as well as mitral pressure half-time, were measured from pulsed-wave or continuous-wave Doppler recordings. Mitral and aortic valve areas and aortic pressure gradients were calculated. In aortic prostheses the valve area decreased and pressure gradient increased progressively in relation to the time from implantation. The mean value (± SD) of the aortic valve area was 67±17 percent of the manufacturer's nominal value at the first examination and 57±20 percent one year later, 51±14 percent two years later, and 46±11 percent three years later (overall differences, p<0.01). In mitral prostheses, reduction of the valve area was not related to the time from implantation. The mean mitral valve area was 45±12 percent of the nominal value at rest and increased to 68±18 percent during exercise at a mean of 45 months after implantation. There was no change in these values at the one-year repeat study. It is concluded that in a population with predominantly pericardial bioprostheses, (1) aortic tissue prostheses showed a progressive functional deterioration demonstrable by Doppler echocardiography, most probably due to degenerative changes; and (2) in mitral tissue prostheses, there was no significant reduction of orifice area in relation to time from implantation. Reduction of mitral valve areas may, to some extent, reflect a less than full opening at rest.

• Timing of invasive procedures during chest tube therapy in spontaneous pneumothorax is undefined. Evaluation of 115 patients with primary and secondary spontaneous pneumothorax treated with tube thoracostomy revealed nearly maximal healing rates after 48 hours without a relevant increase if drainage was maintained for up to 10 days. In secondary spontaneous pneumothorax, a significantly lower healing rate was observed after 48 hours compared with primary spontaneous pneumothorax (60% vs 82%). Therapeutic success was not predictable by single clinical variables available at admission (eg, age, gender, and smoking habits) nor by their combinations. Recurrence rates were 30% in both primary and secondary spontaneous pneumothorax. Hospital stay averaged 6 days in primary and 15 days in secondary spontaneous pneumothorax. Considering their efficacy and the low incidence of complications, the early use of invasive procedures such as surgical pleurectomy, after 48 hours of persistent gas leaking, seems justified. Shorter in-patient care and lower recurrence rates may result.(Arch Surg. 1991;126:764-766)

To assess conventional, large chest tube therapy in iatrogenic pneumothorax and to determine the optimal moment when to use more invasive procedures. Design: Retrospective chart review.

The article reviews the music release "Live at Vier Linder," by B.B. & the Blues Shacks.