A Lazy Bailout Approach for Dual-Criticality Systems on Uniprocessor Platforms

© 2019 by the authors. Licensee MDPI, Basel, Switzerland.A challenge in the design of cyber-physical systems is to integrate the scheduling of tasks of different criticality, while still providing service guarantees for the higher critical tasks in case of resource-shortages caused by faults. While standard real-time scheduling is agnostic to the criticality of tasks, the scheduling of tasks with different criticalities is called mixed-criticality scheduling. In this paper we present the Lazy Bailout Protocol (LBP), a mixed-criticality scheduling method where low-criticality jobs overrunning their time budget cannot threaten the timeliness of high-criticality jobs while at the same time the method tries to complete as many low-criticality jobs as possible. The key principle of LBP is instead of immediately abandoning low-criticality jobs when a high-criticality job overruns its optimistic WCET estimate, to put them in a low-priority queue for later execution. To compare mixed-criticality scheduling methods we introduce a formal quality criterion for mixed-criticality scheduling, which, above all else, compares schedulability of high-criticality jobs and only afterwards the schedulability of low-criticality jobs. Based on this criterion we prove that LBP behaves better than the original {\em Bailout Protocol} (BP). We show that LBP can be further improved by slack time exploitation and by gain time collection at runtime, resulting in LBPSG. We also show that these improvements of LBP perform better than the analogous improvements based on BP.Peer reviewedFinal Published versio

What is the potential for reducing national greenhouse gas emissions from crop and livestock production systems?

Agriculture has a devolved commitment to reduce national emissions of greenhouse gases (GHG). Using a systems model-based life-cycle analysis we explored the potential for reducing GHG in systems used to produce twelve crop and seven livestock commodities. With a functional unit of kg of product, differences in GHG between crops reflect differences in yield. Metabolisable energy (ME) or crude protein (CP) could be used, but deriving an economic value of GB£8.6/GJ ME and GB£0.62/kg CP, leads to a relatively consistent 2.6 kg CO2e/£ nutrient value. Potential GHG reductions ranged from 2% (sugar beet) to 15% (cereals) with agronomic changes, and 4–12% with increased crop yields. The best alternative livestock systems reduced GHG ranging between 7% (beef from the dairy herd) and 21% (extensive sheep meat). Half of the options reduced national production and hence increased imports. Overall, improvements in productivity and use of resources are the best options for reducing GH

The synthesis of an analogue of the locust CRF-like diuretic peptide, and the biological activities of this and some C-terminal fragments.

The synthesis is described of an analogue of the locust CRF-like diuretic peptide in which methionine in positions 1,3, and 13 is replaced by isosteric methyl-homoserine residues. This analogue has been tested for biological activity on Malpighian tubules in vitro, and feeding behavior in vivo. It is highly active in stimulating fluid secretion and accumulation of cAMP in tubules, and on increasing the latency to feed and reducing meal duration. A 15 residue fragment from the C-terminus of the CRF-like peptide, Locmi-DP32–46, is fully active in the feeding assay, but has only weak ability to stimulate the accumulation of cAMP in tubules. Two smaller fragments, Locmi-DP32–37 and Locmi-DP41–46, were tested but neither had consistent biological activity in any of the assays used here. None of the peptides tested have any substantive activity in increasing cGMP in tubules

Citizen schools offer a chance to rebuild our democracy fromthe bottom up

The Conservative Party’s ‘Big Society’ was supposed to bring about a new age of public involvement and active citizen participation in public affairs. But as that agenda crumbles, Jamie Audsley, the co-author of a new IPPR report, argues that to achieve those ends, we must place the citizenship agenda at the heart of every school

Energy and environmental burdens of organic and non-organic agriculture and horticulture

Production of 10 major commodities in England and Wales was studied using Life Cycle Analysis (LCA). Organic and non-organic (contemporary conventional) systems were compared. Organic production was generally less energy consuming, except for poultry meat, eggs and tomatoes. Environmental burdens, such as global warming potential or eutrophication were often greater per unit of production from organic than non-organic systems

A two-stage stochastic programming with recourse model for determining robust planting plans in horticulture

A two-stage stochastic programming with recourse model for the problem of determining optimal planting plans for a vegetable crop is presented in this paper. Uncertainty caused by factors such as weather on yields is a major influence on many systems arising in horticulture. Traditional linear programming models are generally unsatisfactory in dealing with the uncertainty and produce solutions that are considered to involve an unacceptable level of risk. The first stage of the model relates to finding a planting plan which is common to all scenarios and the second stage is concerned with deriving a harvesting schedule for each scenario. Solutions are obtained for a range of risk aversion factors that not only result in greater expected profit compared to the corresponding deterministic model, but also are more robust

Socio-economic Scenarios of Agricultural Land Use Change in Central and Eastern European Countries

The study presented in this paper is part of the ACCELERATES (Assessing Climate Change Effects on Land Use and Ecosystems from Regional Analysis to The European Scale) project whose main goal is the construction of integrated predictions of future land use in Europe. The scenarios constructed in the project include estimates not only due to changes in the climate baseline, but also estimates due to possible future changes in socio-economics. The overall aim of the ACCELERATES was to assess the vulnerability of European agroecosystems based on economic and environmental considerations in term of both their sensitivity and capacity to adapt changes. The historical background, the type of economy, the policy aim and governance and importance of agriculture in the overall national economy have created large differences between Western and Central and Eastern European countries (CEECs). This paper focuses on vulnerability of the farm sector and rural economy of CEECs.ACCELERATES, climate change, agricultural land use, scenario, Land Economics/Use, Q24,

Unraveling Lessons from Mary Oliver

A young poet describes the ways Oliver’s commitment to the craft inspired her

VCDC: The Virtualized Complicated Device Controller

I/O virtualization enables time and space multiplexing of I/O devices, by mapping multiple logical I/O devices upon a smaller number of physical devices. However, due to the existence of additional virtualization layers, requesting an I/O from a guest virtual machine requires complicated sequences of operations. This leads to I/O performance losses, and makes precise timing of I/O operations unpredictable. This paper proposes a hardware I/O virtualization system, termed the Virtualized Complicated Device Controller (VCDC). This I/O system allows user applications to access and operate I/O devices directly from guest VMs, and bypasses the guest OS, the Virtual Machine Monitor (VMM) and low layer I/O drivers. We show that the VCDC efficiently reduces the software overhead and enhances the I/O performance and timing predictability. Furthermore, VCDC also exhibits good scalability that can handle I/O requests from variable number of CPUs in a system