| 1. |
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| 2. |
- Lindgren, Per, et al.
(författare)
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Robust real-time applications in Timber
- 2006
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Ingår i: 2006 IEEE International Conference on Electro/information Technology. - Piscataway, NJ : IEEE Communications Society. - 0780395921 ; , s. 191-196
-
Konferensbidrag (refereegranskat)abstract
- Embedded systems are often operating under hard real-time constraints, for example in automotive applications. For such systems, robustness and reliability are crucial, which calls for rigorous system design and methodologies for validation. In this paper we advocate a design methodology for robust, realtime systems, based on Timber; a pure reactive system model that allows for formal reasoning about various system properties. We outline how system specifications in Timber can be "compiled" into efficient standalone executables for general light-weight microcontroller platforms. Methods for resource analysis and implications to system dimensioning and validation are further discussed.
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| 3. |
- Lindgren, Per, et al.
(författare)
-
TinyTimber, reactive objects in C for real-time embedded systems
- 2008
-
Ingår i: Proceedings, Design, Automation and Test in Europe. - New York : ACM Digital Library. - 9783981080131 ; , s. 1382-1385
-
Konferensbidrag (refereegranskat)abstract
- Embedded systems are often operating under hard real-time constraints. Such systems are naturally described as time-bound reactions to external events, a point of view made manifest in the high-level programming and systems modeling language Timber. In this paper we demonstrate how the Timber semantics for parallel reactive objects translates to embedded real-time programming in C. This is accomplished through the use of a minimalistic Timber Run-Time system, TinyTimber (TT). The TT kernel ensures state integrity, and performs scheduling of events based on given time-bounds in compliance with the Timber semantics. In this way, we avoid the volatile task of explicitly coding parallelism in terms of processes/threads/semaphores/monitors, and side-step the delicate task to encode time-bounds into priorities. In this paper, the TT kernel design is presented and performance metrics are presented for a number of representative embedded platforms, ranging from small 8-bit to more potent 32-bit micro controllers. The resulting system runs on bare metal, completely free of references to external code (even C-lib) which provides a solid basis for further analysis. In comparison to a traditional thread based real-time operating system for embedded applications (FreeRTOS), TT has tighter timing performance and considerably lower code complexity. In conclusion, TinyTimber is a viable alternative for implementing embedded real-time applications in C today.
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| 4. |
- Lindhult, Johan
(författare)
-
Operational Semantics for PLEX : A Basis for Safe Parallelization
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The emerge of multi-core computers implies a major challenge for existing software. Due to simpler cores, the applications will face decreased performance if not executed in parallel. The problem is that much of the software is sequential.Central parts of the AXE telephone exchange system from Ericsson is programmed in the language PLEX. The current software is executed on a single-processor architecture, and assumes non-preemptive execution.This thesis presents two versions of an operational semantics for PLEX; one that models execution on the current, single-processor, architecture, and one that models execution on an assumed shared-memory architecture. A formal semantics of the language is a necessity for ensuring correctness of program analysis, and program transformations.We also report on a case study of the potential memory conflicts that may arise when the existing code is allowed to be executed in parallel. We show that simple static methods are sufficient to resolve many of the potential conflicts, thereby reducing the amount of manual work that probably still needs to be performed in order to adapt the code for parallel processing.
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| 5. |
- Svensson, L., et al.
(författare)
-
Are predictors for myocardial infarction the same for women and men when evaluated prior to hospital admission?
- 2006
-
Ingår i: Int J Cardiol. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 109:2, s. 241-7
-
Tidskriftsartikel (refereegranskat)abstract
- AIM: To describe predictors of myocardial infarction prior to hospital admission in women and men among patients with a suspected acute coronary syndrome without ST-elevation. DESIGN: Prospective observational study in Stockholm and Goteborg, Sweden. RESULTS: Of 433 patients who did fulfill the inclusion criteria 45% were women. Fewer women (17%) than men (26%) developed acute myocardial infarction (AMI) (p=0.054), particularly among patients with initial ST-depression, in whom AMI was developed in 22% of women and 54% of men (p = 0.001). Predictors for infarct development in women were: a history of AMI and advanced age. Among men they were: initial ST-depression or a Q-wave on ECG and elevation of biochemical markers (both recorded on admission of the ambulance crew). There was a significant interaction between gender and the influence of ST-depression on the risk for development of myocardial infarction (p < 0.05). CONCLUSION: Among patients transported with ambulance due to a suspected acute coronary syndrome and no ST-elevation fewer women than men seem to develop AMI particularly among patients with ST-depression. These results suggest that early prediction of myocardial infarction might differ between women and men with acute chest pain.
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| 6. |
- Berglund, Felix, et al.
(författare)
-
Acute and long-term renal effects after iodine contrast media-enhanced computerised tomography in the critically ill-a retrospective bi-centre cohort study.
- 2024
-
Ingår i: European Radiology. - 0938-7994 .- 1432-1084. ; 34:3, s. 1736-1745
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To determine if current clinical use of iodine contrast media (ICM) for computerised tomography (CT) increases the risk of acute kidney injury (AKI) and long-term decline in renal function in patients treated in intensive care.METHODS: A retrospective bi-centre cohort study was performed with critically ill subjects undergoing either ICM-enhanced or unenhanced CT. AKI was defined and staged based on the Kidney Disease Improve Global Outcome AKI criteria, using both creatinine and urine output criteria. Follow-up plasma creatinine was recorded three to six months after CT to assess any long-term effects of ICM on renal function.RESULTS: In total, 611 patients were included in the final analysis, median age was 65.0 years (48.0-73.0, quartile 1-quartile 3 (IQR)) and 62.5% were male. Renal replacement therapy was used post-CT in 12.9% and 180-day mortality was 31.2%. Plasma creatinine level on day of CT was 100.0 µmol/L (66.0-166.5, IQR) for non-ICM group and 77.0 µmol/L (59.0-109.0, IQR) for the ICM group. The adjusted odds ratio for developing AKI if the patient received ICM was 1.03 (95% confidence interval 0.64-1.66, p = 0.90). No significant association between ICM and increase in plasma creatinine at long-term follow-up was found, with an adjusted effect size of 2.92 (95% confidence interval - 6.52-12.36, p = 0.543).CONCLUSIONS: The results of this study do not indicate an increased risk of AKI or long-term decline in renal function when ICM is used for enhanced CT in patients treated at intensive care units.CLINICAL RELEVANCE STATEMENT: Patients treated in intensive care units had no increased risk of acute kidney injury or persistent decline in renal function after contrast-enhanced CT. This information underlines the need for a proper risk-reward assessment before denying patients a contrast-enhanced CT.KEY POINTS: • Iodine contrast media is considered a risk factor for the development of acute kidney injury. • Patients receiving iodine contrast media did not have an increased incidence of acute kidney injury or persistent decline in renal function. • A more clearly defined risk of iodine contrast media helps guide clinical decisions whether to perform contrast-enhanced CTs or not.
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| 7. |
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| 8. |
- Carlsson, Magnus, et al.
(författare)
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The semantic layers of Timber
- 2003
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Ingår i: Programming languages and systems. - Berlin, Heidelberg : Encyclopedia of Global Archaeology/Springer Verlag. - 9783540205364 - 9783540400189 ; , s. 339-356
-
Konferensbidrag (refereegranskat)abstract
- We present a three-layered semantics of Timber, a language designed for programming real-time systems in a reactive, object-oriented style. The innermost layer amounts to a traditional deterministic, pure, functional language, around which we formulate a middle layer of concurrent objects, in terms of a monadic transition semantics. The outermost layer, where the language is married to deadline-driven scheduling theory, is where we define message ordering and CPU allocation to actions. Our main contributions are a formalized notion of a time-constrained reaction, and a demonstration of how scheduling theory, process calculii, and the lambda calculus can be jointly applied to obtain a direct and succinct semantics of a complex, real-world programming language with well-defined real-time behavior.
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| 9. |
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| 10. |
- Dalin, Peter, et al.
(författare)
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Importance of temperature for the performance and biocontrol efficiency of the parasitoid Perilitus brevicollis (Hymenoptera: Braconidae) on Salix
- 2012
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Ingår i: BioControl. - : Springer Science and Business Media LLC. - 1386-6141 .- 1573-8248. ; 57, s. 611-618
-
Tidskriftsartikel (refereegranskat)abstract
- With the prospect of warmer temperatures as a consequence of ongoing climate change, it is important to investigate how such increases will affect parasitoids and their top-down suppression of herbivory in agroecosystems. Here we studied how the performance and biocontrol efficiency of the willow "bodyguard" Perilitus brevicollis Haliday (Hymenoptera: Braconidae) were affected at different constant temperatures (10, 15, 20, 25A degrees C) when parasitizing a pest insect, the blue willow beetle (Phratora vulgatissima L., Coleoptera: Chrysomelidae). Parasitism did not reduce herbivory at all at 10A degrees C, indicating poor biocontrol efficiency at low temperatures. At higher temperatures, however, parasitism reduced herbivory substantially, implying that biocontrol may be promoted by a warmer climate. Parasitoid performance (survival and development rate) generally increased with increasing temperature up to 20A degrees C. The only exception was body size, which followed the temperature-size rule and decreased with increasing temperature. Our results indicate that a warmer climate may enhance the biocontrol of the blue willow beetle in environments that currently are cooler than the parasitoid's optimal temperature for development.
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| 11. |
- Feiertag, Nico, et al.
(författare)
-
A compositional framework for end-to-end path delay calculation of automotive systems under different path semantics
- 2009
-
Ingår i: Real-Time Systems Symposium, 2008. - Piscataway, NJ : IEEE Communications Society. - 9781424436545
-
Konferensbidrag (refereegranskat)abstract
- While the real-time systems community has developed very valuable approaches to timing and scheduling analysis for processors and buses over the last four decades, another very relevant issue has received only limited attention: end-to-end timing. Most of the known work poses restrictions on specific task activation and communication mechanisms, e.g. unbounded FIFO queues along event-triggered paths. In automotive systems, however, register buffers and periodic sampling are far more common. In this paper, we present a formal framework for the calculation of end-to-end latencies in multi-rate, register-based systems. We show that in systems with sampling, analysis must distinguish between different "meanings" of end-to-end timing. For instance, control engineers are mostly concerned with the "maximum age of data", i.e. the worst-case timing of the latest possible signal. In body electronics, the "first reaction" is key, i.e. worst-case timing of the earliest possible signal. Because the analysis of either case can be different, a clear distinction is mandatory. This paper gives examples and introduces the notion of such end-to-end timing semantics, thereby considering the specific mechanisms and effects typically found in automotive execution platforms such as over- and under-sampling and jitter.
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| 12. |
- Feiertag, Nico, et al.
(författare)
-
A Compositional Framework for End-to-End Path Delay Calculation of Automotive Systems under Different Path Semantics
- 2008
-
Ingår i: Proceedings of the IEEE Real-Time System Symposium − Workshop on Compositional Theory and Technology for Real-Time Embedded Systems, Barcelona, Spain, November 30, 2008.
-
Konferensbidrag (refereegranskat)abstract
- While the real-time systems community has developed very valuable approaches to timing and scheduling analysis for processors and buses over the last four decades, another very relevant issue has received only limited attention: end-to-end timing. Most of the known work poses restrictions on specific task activation and communication mechanisms, e.g. unbounded FIFO queues along event-triggered paths. In automotive systems, however, register buffers and periodic sampling are far more common. In this paper, we present a formal framework for the calculation of end-to-end latencies in multi-rate, register-based systems. We show that in systems with sampling, analysis must distinguish between different "meanings" of end-to-end timing. For instance, control engineers are mostly concerned with the "maximum age of data", i.e. the worst-case timing of the latest possible signal. In body electronics, the "first reaction" is key, i.e. worst-case timing of the earliest possible signal. Because the analysis of either case can be different, a clear distinction is mandatory. This paper gives examples and introduces the notion of such end-to-end timing semantics, thereby considering the specific mechanisms and effects typically found in automotive execution platforms such as over- and under-sampling and jitter.
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| 13. |
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| 14. |
- Hollenberg, Jacob, et al.
(författare)
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Difference in survival after out-of-hospital cardiac arrest between the two largest cities in Sweden: a matter of time?
- 2005
-
Ingår i: J Intern Med. - : Wiley. - 0954-6820 .- 1365-2796. ; 257:3, s. 247-54
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Dramatic differences in survival after out-of-hospital cardiac arrests (OHCA) reported from different geographical locations require analysis. We therefore compared patients with OHCA in the two largest cities in Sweden with regard to various factors at resuscitation and outcome. SETTING: All patients suffering an OHCA in Stockholm and Goteborg between 1 January 2000 and 30 June 2001, in whom cardiopulmonary resuscitation (CPR) was attempted were included in this retrospective analysis. RESULTS: All together, 969 OHCA in Stockholm and 398 in Goteborg were registered during the 18-month study period. There were no differences in terms of age, gender, and percentage of witnessed cases or percentage of patients who had received bystander CPR. However, the percentage of patients with ventricular fibrillation (VF) at arrival of the ambulance crew was 18% in Stockholm versus 31% in Goteborg (P <0.0001). The percentage of patients who were alive 1 month after cardiac arrest was 2.5% in Stockholm versus 6.8% in Goteborg (P=0.0008). Various time intervals such as cardiac arrest to calling for an ambulance, cardiac arrest to the start of CPR and calling for an ambulance to its arrival were all significantly longer in Stockholm than in Goteborg. CONCLUSION: Survival was almost three times higher in Goteborg than in Stockholm amongst patients suffering an OHCA. This is primarily explained by a higher occurrence of VF at the time of arrival of the ambulance crew, which in turn probably is explained by shorter delays in Goteborg. The reason for the difference in time intervals is most likely multifactorial, with a significantly higher ambulance density in Goteborg as one possible explanation.
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| 15. |
- Jonsson, Peter A., et al.
(författare)
-
On building a supercompiler for GHC
- 2008
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Supercompilation is a program transformation that removes intermediate structures and performs program specialization. We discuss problems and necessary steps for building a supercompiler for GHC.
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| 16. |
- Jonsson, Peter A., et al.
(författare)
-
Positive supercompilation for a higher order call-by-value language : extended proofs
- 2008
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Previous deforestation and supercompilation algorithms may introduce accidental termination when applied to call-by-value programs. This hides looping bugs from the programmer, and changes the behavior of a program depending on whether it is optimized or not. We present a supercompilation algorithm for a higher-order call-by-value language and we prove that the algorithm both terminates and preserves termination properties. This algorithm utilizes strictness information for deciding whether to substitute or not and compares favorably with previous call-by-name transformations.
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| 17. |
- Jonsson, Peter A., et al.
(författare)
-
Positive supercompilation for a higher order call-by-value language
- 2009
-
Ingår i: Proceedings of the 36th Annual ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages. - New York : ACM Digital Library. - 9781605583792 ; , s. 277-288
-
Konferensbidrag (refereegranskat)abstract
- Previous deforestation and supercompilation algorithms may introduce accidental termination when applied to call-by-value programs. This hides looping bugs from the programmer, and changes the behavior of a program depending on whether it is optimized or not. We present a supercompilation algorithm for a higher-order call-by-value language and we prove that the algorithm both terminates and preserves termination properties. This algorithm utilizes strictness information for deciding whether to substitute or not and compares favorably with previous call-by-name transformations.
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| 18. |
- Jonsson, Peter A., et al.
(författare)
-
Positive supercompilation for a higher-order call-by-value language
- 2010
-
Ingår i: Logical Methods in Computer Science. - 1860-5974. ; 6:3, s. 1-39
-
Tidskriftsartikel (refereegranskat)abstract
- Previous deforestation and supercompilation algorithms may introduce accidental termination when applied to call-by-value programs. This hides looping bugs from the programmer, and changes the behavior of a program depending on whether it is optimized or not. We present a supercompilation algorithm for a higher-order call-by-value language and prove that the algorithm both terminates and preserves termination properties. This algorithm utilizes strictness information to decide whether to substitute or not and compares favorably with previous call-by-name transformations.
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| 19. |
- Jonsson, Peter, et al.
(författare)
-
Strengthening supercompilation for call-by-value languages
- 2010
-
Ingår i: Proceedings of the Second International Valentin Turchin Memorial Workshop on Metacomputation in Russia. - Pereslavl Zalessky : Ailamazyan University of Pereslavl. - 9785901795217 ; , s. 64-81
-
Konferensbidrag (refereegranskat)abstract
- A termination preserving supercompiler for a call-by-value language sometimes fails to remove intermediate structures that a supercompiler for a call-by-name language would remove. This discrepancy in power stems from the fact that many function bodies are either non-linear in use of an important variable or often start with a pattern match on their first argument and are therefore not strict in all their arguments. As a consequence, intermediate structures are left in the output program, making it slower. We present a revised supercompilation algorithm for a call-by-value language that propagates let-bindings into case-branches and uses termination analysis to remove dead code. This allows the algorithm to remove all intermediate structures for common examples where previous algorithms for call-by-value languages had to leave the intermediate structures in place.
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| 20. |
- Jonsson, Peter, et al.
(författare)
-
Taming code explosion in supercompilation
- 2011
-
Ingår i: Proceedings of the 20th ACM SIGPLAN workshop on Partial evaluation and program manipulation. - New York : ACM Digital Library. - 9781450304856 ; , s. 33-42
-
Konferensbidrag (refereegranskat)abstract
- Supercompilation algorithms can perform great optimizations but sometimes suffer from the problem of code explosion. This results in huge binaries which might hurt the performance on a modern processor. We present a supercompilation algorithm that is fast enough to speculatively supercompile expressions and discard the result if it turned out bad. This allows us to supercompile large parts of the imaginary and spectral parts of nofib in a matter of seconds while keeping the binary size increase below 5%.
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| 21. |
- Kero, Martin, et al.
(författare)
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A correct and useful incremental copying garbage collector
- 2007
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Ingår i: Proceedings of the the 2007 International Symposium on Memory Management. - New York : ACM Digital Library. - 9781595938930 ; , s. 129-140
-
Konferensbidrag (refereegranskat)abstract
- Designing a garbage collector with real-time properties is a particularly difficult task, involving the construction of both an incremental run-time algorithm as well as methods enabling a priori reasoning about schedulability in two dimensions (time and memory usage in conjunction). In order to comply with such ambitious goals with any amount of formal rigor, a comprehensive understanding of the actual algorithm used is of course a fundamental requirement. In this paper we present a formal model of an incremental copying garbage collector, where each atomic increment is modeled as a transition between states of a heap process. Soundness of the algorithm is shown by proving that the garbage collecting heap process is weakly bisimilar to a non-collecting heap with infinite storage space. In addition, we show that our collector is both terminating and useful, in the sense that it actually recovers the unreachable parts of any given heap in a finite number of steps.
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| 22. |
- Kero, Martin, et al.
(författare)
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Live heap space bounds for real-time systems
- 2010
-
Ingår i: Programming languages and systems. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. - 9783642171635 ; , s. 287-303
-
Konferensbidrag (refereegranskat)abstract
- Live heap space analyses have so far been concerned with the standard sequential programming model. However, that model is not very well suited for embedded real-time systems, where fragments of code execute concurrently and in orders determined by periodic and sporadic events. Schedulability analysis has shown that the programming model of real-time systems is not fundamentally in conflict with static predictability, but in contrast to accumulative properties like time, live heap space usage exhibits a very state-dependent behavior that renders direct application of schedulability analysis techniques unsuitable.In this paper we propose an analysis of live heap space upper bounds for real-time systems based on an accurate prediction of task execution orders. The key component of our analysis is the construction of a non-deterministic finite state machine capturing all task executions that are legal under given timing assumptions. By adding heap usage information inferred for each sequential task, our analysis finds an upper bound on the inter-task heap demands as the solution to an integer linear programming problem. Values so obtained are suitable inputs to other analyses depending on the size of a system’s persistent state, such as running time prediction for a concurrent tracing garbage collector.
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| 23. |
- Kero, Martin, et al.
(författare)
-
Timber as an RTOS for small embedded devices
- 2005
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Ingår i: PREALWSN 2005. - Kista : Swedish Institute of Computer Science.
-
Konferensbidrag (refereegranskat)abstract
- Software development for small, real-time and resource constrained, embedded systems is becoming increasingly complex. To be able to guarantee robustness and reliability, the underlying infrastructure should not be based upon ad hoc solutions. In this paper we identify three key features of a minimalistic Real-Time Operating System (RTOS), and presents the run-time system of Timber, a reactive deadlinedriven programming language. We scrutinize the functionalities of the run-time system in the light of real-time requirements, and emphasize the importance of integrating an adequate notion of time, both semantically in the programming interface as well as part of the run-time system.
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| 24. |
- Li, Hailong, 1976-, et al.
(författare)
-
Using the solid digestate from a wet anaerobic digestion process as an energy resource
- 2013
-
Ingår i: Energy technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 1:1, s. 94-101
-
Tidskriftsartikel (refereegranskat)abstract
- The wet anaerobic digestion process is a widely used method to produce biogas from biomass. To avoid the risks involved with using the digestion waste as a fertilizer, this work investigates the possibilities to use the solid digestate as an energy resource to produce heat and electricity, which could save some energy currently consumed by the plant and, therefore, may increase the overall efficiency of a biogas plant. Simulations were conducted based on real data from the Växtkraft biogas plant in Västerås, Sweden as a case study. Results show that it is necessary to dry the solid digestate before combustion and include flue-gas condensation to recover enough heat for the drying process. When a steam turbine cycle is integrated, the generated electricity could cover 13–18 % of the total electricity consumption of the plant, depending on the degree of dryness. In addition, reducing the digestion period can increase the carbon content (ultimate analysis), the heating value, and the mass flow of the solid digestate. As a result, the production of electricity and heat is augmented in the steam turbine cycle. However, the production of biogas is reduced. Therefore, a comprehensive economic evaluation is suggested to optimize a biogas plant that uses the solid digestate from a wet anaerobic digestion process as an energy resource.
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| 25. |
- Lindgren, Per, et al.
(författare)
-
Time for Timber
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Embedded systems are often operating under hard real-time constraints, while at the same time being constrained by severe restrictions on power consumption. For such systems, robustness and reliability can be a question of life and death, which calls for rigorous system design and methodologies for validation. In this paper we advocate a design methodology for low-power, real-time systems, based on Timber; a pure reactive system model that allows for formal reasoning about various system properties. We outline how system specifications in Timber can be "compiled" into efficient standalone executables for general light- weight microcontroller based target platforms. Methods for resource analysis and implications to system dimensioning and validation are further discussed.
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| 26. |
- Lisper, Björn, et al.
(författare)
-
A Simple and Flexible Timing Constraint Logic
- 2012
-
Ingår i: Lecture Notes in Computer Science, vol, 7610. - Berlin, Heidelberg : Springer. - 9783642340314 ; , s. 80-95, s. 80-95
-
Bokkapitel (refereegranskat)abstract
- Formats for describing timing behaviors range from fixed menus of standard patterns, to fully open-ended behavioral definitions; of which some may be supported by formal semantic underpinnings, while others are better characterized as primarily informal notations. Timing descriptions that allow flexible extension within a fully formalized framework constitute a particularly interesting area in this respect. We present a small logic for expressing timing constraints in such an open-ended fashion, sprung out of our work with timing constraint semantics in the TIMMO-2-USE project. The result is a non-modal, first-order logic over reals and sets of reals, which references the constrained objects solely in terms of event occurrences. Both finite and infinite behaviors may be expressed, and a core feature of the logic is the ability to restrict any constraint to just the finite ranges when a certain system mode is active. Full syntactic and semantic definitions of our formula language are given, and as an indicator of its expressiveness, we show how to express all constraint forms currently defined by TIMMO-2-USE and AUTOSAR. A separate section deals with the support for mode-dependencies that have been proposed for both frameworks, and we demonstrate by an example how our generic mode-restriction mechanism formalizes the details of such an extension.
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| 27. |
- Lisper, Björn, et al.
(författare)
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Timing constraints : Theory meets practice
- 2012
-
Ingår i: Lecture Notes in Computer Science, vol. 7610. - Berlin, Heidelberg : Springer. - 9783642340314 ; , s. 78-79, s. 78-79
-
Bokkapitel (refereegranskat)abstract
- Many embedded systems must satisfy timing requirements, which describe how these systems should behave with respect to timing. Such requirements must be dealt with throughout the system development process: from their initial specification, expressed at an abstract level, through the increasingly concrete layers, to the final implementation level. There is a growing awareness that this process needs support from languages, tools, and methodologies.
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| 28. |
- Nordlander, Andreas, et al.
(författare)
-
Demokratisk och traditionsburen kunskap
- 2006
-
Ingår i: Frihet och gränser: filosofiska perspektiv på religionsfrihet och tolerans. - 9789171397799
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 29. |
- Nordlander, Johan
(författare)
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Anteckningar om några norrländska ortnamn
- 1889
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Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 7:2, s. 164-176
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 30. |
- Nordlander, Johan
(författare)
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Ett ångermanländskt kalvarieberg
- 1926
-
Ingår i: Fornvännen. - 0015-7813 .- 1404-9430. ; , s. 163-170
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 31. |
- Nordlander, Johan
(författare)
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Försvarskyrkor i Norrland
- 1909
-
Ingår i: Fornvännen. - 0015-7813 .- 1404-9430. ; , s. 50-54
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 32. |
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| 33. |
- Nordlander, Johan
(författare)
-
Lapparnes ålder i södra Norrland
- 1899
-
Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 10, s. 216-228
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 34. |
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| 35. |
- Nordlander, Johan
(författare)
-
Mytiska sägner från Norrland
- 1882
-
Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 5:2, s. 171-202
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 36. |
- Nordlander, Johan
(författare)
-
Namnen Vi, Vibol och Vibro i Gestrikland
- 1905
-
Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 12:3, s. 314-318
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 37. |
- Nordlander, Johan
(författare)
-
Några norrländska ortnamns etymologi
- 1896
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Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 9:3, s. 298-318
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 38. |
- Nordlander, Johan
(författare)
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Några notiser om 'Jemptelandz Lappemark'
- 1902
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Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 11:3, s. 327-334
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 39. |
- Nordlander, Johan
(författare)
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Om fingrarnes namn i svenskan
- 1883
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Ingår i: Svenska fornminnesföreningens tidskrift. - 0283-2496. ; 5:3, s. 272-287
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Nordlander, Johan
(författare)
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Platsen för Medelpads landsting
- 1927
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Ingår i: Fornvännen. - 0015-7813 .- 1404-9430. ; 182
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 44. |
- Nordlander, Johan
(författare)
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Polymorphic subtyping in O'Haskell
- 2002
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Ingår i: Science of Computer Programming. - 0167-6423 .- 1872-7964. ; 43:2-3, s. 93-127
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Tidskriftsartikel (refereegranskat)abstract
- O'Haskell is a programming language derived from Haskell by the addition of concurrent reactive objects and subtyping. Because Haskell already encompasses an advanced type system with polymorphism and overloading, the type system of O'Haskell is much richer than what is the norm in almost any widespread object-oriented or functional language. Yet, there is strong evidence that O'Haskell is not a complex language to use, and that both Java and Haskell programmers can easily find their way with its polymorphic subtyping system. This paper describes the type system of O'Haskell both formally and from a programmer's point of view; the latter task is accomplished with the aid of an illustrative, real-world programming example: a strongly typed interface to the graphical toolkit Tk.
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| 45. |
- Nordlander, Johan
(författare)
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Pragmatic subtyping in polymorphic languages
- 1999
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Ingår i: Proceedings of the third ACM SIGPLAN International Conference on Functional Programming. - : IEEE Communications Society. - 9781581130249 ; , s. 216-227
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Konferensbidrag (refereegranskat)abstract
- We present a subtyping extension to the Hindley/Milner type system that is based on name inequivalence. This approach allows the subtype relation to be de ned by incremental construction of polymorphic records and datatypes, in a way that subsumes the basic type systems of both languages like ML and Java. As the main contribution of the paper, we describe a partial type inference algorithm for the extended system which favours succinctness over generality, in the sense that it never infers types with subtype constraints. The algorithm is based on an effcient approximating constraint solver, and is able to type a wide range of programs that utilize subtyping and polymorphism in a non-trivial way. Since constrained types are not inferred, the algorithm cannot be complete; however, we provide a completeness result w. r. t. the Hindley/Milner type system as a form of characterizing lower bound.
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| 46. |
- Nordlander, Johan
(författare)
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Programming with the TinyTimber kernel
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document describes the C programming interface to TinyTimber, a very small and lightweight run-time kernel for event-driven embedded systems.
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| 47. |
- Nordlander, Johan, et al.
(författare)
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Programming with time-constrained reactions
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we argue that a programming language for real-time systems should support the declaration of time-constraints, and that those constraints should attach to a welldeveloped notion of reactions. To make our claims more precise, we introduce Timber, which is a concurrent programming language based on a model of non-blocking, reactive objects. Timber supports both upper and lower time constraints on a reaction, where upper constraints correspond to classical deadlines, and lower constraints constitute the systematic capturing of well-defined points in the future as events in their own right. A series of programming examples illustrates how these mechanisms can be used to express simple solutions to common problems in practical real-time programming, and the relation between Timber and deadline-based scheduling theory is explored.
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| 48. |
- Nordlander, Johan, et al.
(författare)
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Reactive objects
- 2002
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Ingår i: Fifth IEEE International Symposium on Object-Oriented Real-Time Distributed Computing. - Piscataway, NJ : IEEE Communications Society. ; , s. 155-158
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Konferensbidrag (refereegranskat)abstract
- Object-oriented, concurrent, and event-based programming models provide a natural framework in which to express the behavior of distributed and embedded software systems. However, contemporary programming languages still base their I/O primitives on a model in which the environment is assumed to be centrally controlled and synchronous, and interactions with the environment carried out through blocking subroutine calls. The gap between this view and the natural asynchrony of the real world has made event-based programming a complex and error-prone activity, despite recent focus on event-based frameworks and middleware. In this paper we present a consistent model of event-based concurrency, centered around the notion of reactive objects. This model relieves the object-oriented paradigm from the idea of transparent blocking, and naturally enforces reactivity and state consistency. We illustrate our point by a program example that offers substantial improvements in size and simplicity over a corresponding Java-based solution.
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| 49. |
- Nordlander, Johan, 1962
(författare)
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Reactive Objects and Functional Programming
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The construction of robust distributed and interactive software is still a challenging task, despite the recent popularity-increase for languages that take advanced programming concepts into the mainstream. Several problematic areas can be identified: most languages require the reactivity of a system to be manually upheld by careful avoidance of blocking operations; mathematical values often need to be encoded in terms of stateful objects or vice versa; concurrency is particularly tricky in conjunction with encapsulated software components; and static type safety is often compromised because of the lack of simultaneous support for both subtyping and polymorphism. This thesis presents a programming language, O'Haskell, that has been consciously designed with these considerations in mind. O'Haskell is defined by conservatively extending the purely functional language Haskell with the following features: A central structuring mechanism based on reactive objects, which unify the notions of objects and concurrent processes. Reactive objects are asynchronous, state-encapsulating servers whose purpose is to react to input messages; they cannot actively block execution or selectively filter their sources of input. A monadic layer of object-based computational effects, which clearly separates stateful objects from stateless values. Apart from higher-order functions and recursive data structures, the latter notion also includes first-class commands, object templates, and methods. A safe, polymorphic type system with declared record and datatype subtyping, supported by a powerful partial type inference algorithm. It is claimed that these features make O'Haskell especially well-adapted for the task of modern software construction. The thesis presents O'Haskell from both a practical and a theoretical perspective. The practical contributions are a full implementation of the language, a number of non-trivial programming examples that illustrate the merits of reactive objects in a realistic context, and several reusable programming methods for such applications as graphical user interfaces, embedded controllers, and network protocols. The theoretical results serve to substantiate the informal claim made regarding usability, and include a provably sound polymorphic subtyping system, soundness and partial completeness for the inference algorithm, a formal dynamic semantics, and a result that characterizes the conservative extension of a purely functional language with state and concurrency.
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| 50. |
- Nordlander, Johan, et al.
(författare)
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Reactive objects in a functional language : an escape from the Evil I
- 1997
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Ingår i: Proceedings of the 1997 ACM SIGPLAN International Conference on Functional Programming. - New York : ACM Digital Library. - 0897919181
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Konferensbidrag (refereegranskat)abstract
- We present an extension to Haskell which supports reactive, concurrent programming with objects, sans the problematic blocking input. We give a semantics together with a number of programming examples, and show an implementation based on a preprocessor and a library implementing seven monadic constants.
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