Fallback Strategies Research Articles

Impact of ICT Latency, Data Loss and Data Corruption on Active Distribution Network Control

The ongoing changes in modern power systems towards increasingly decentralized systems render the coordination of generation assets and the corresponding dependency on Information and Communication Technology highly relevant. This work demonstrates the impact of three types of ICT errors, namely delayed data, data loss and data corruption, on the control of distributed energy resources in an active distribution network. The settling time of the active power response at the interconnection point between the distribution and transmission system is investigated in the simulations. Additionally, two fallback strategies to mitigate the impact of data loss are proposed and evaluated with regard to their impact on the controller’s response. Finally, a generalized, aggregated service state description is proposed in order to capture the performance of the active distribution network service. It is meant to improve the interpretability of the results, which can be used to compare service designs and setups.

Beyond Deadlock

Efforts to ban Autonomous Weapon Systems were both unsuccessful and controversial. Simultaneously the need to address the detrimental aspects of AWS development and proliferation continues to grow in scope and urgency. The article presents several regulatory solutions capable of addressing the issue while simultaneously respecting the requirements of military necessity and so attracting a broad consensus. Two much stricter solutions – regional AWS bans and adoption of a no first use policy – are also presented as fallback strategies in case achieving AWS’ compliance with the Laws of Armed Conflict proved elusive. Together, the solutions presented form an outline of a flexible regulatory strategy able to adjust to different technological outcomes and providing a sensible compromise to solve the current deadlock on the AWS issue.

A Reconfigurable Framework for Vehicle Localization in Urban Areas.

Accurate localization for autonomous vehicle operations is essential in dense urban areas. In order to ensure safety, positioning algorithms should implement fault detection and fallback strategies. While many strategies stop the vehicle once a failure is detected, in this work a new framework is proposed that includes an improved reconfiguration module to evaluate the failure scenario and offer alternative positioning strategies, allowing continued driving in degraded mode until a critical failure is detected. Furthermore, as many failures in sensors can be temporary, such as GPS signal interruption, the proposed approach allows the return to a non-fault state while resetting the alternative algorithms used in the temporary failure scenario. The proposed localization framework is validated in a series of experiments carried out in a simulation environment. Results demonstrate proper localization for the driving task even in the presence of sensor failure, only stopping the vehicle when a fully degraded state is achieved. Moreover, reconfiguration strategies have proven to consistently reset the accumulated drift of the alternative positioning algorithms, improving the overall performance and bounding the mean error.

Adapting Time Headway in Cooperative Adaptive Cruise Control to Network Reliability

Wireless network impairment results in adverse effect on string stability of a Cooperative Adaptive Cruise Control (CACC) platoon that relies on the wireless network, causing disturbances in the platoon that may lead to a collision. Previous work in the literature proposed fallback strategies that utilizes on-board sensors to recover in case of wireless network impairment, those methods assumes a fixed time headway value. In this paper, we study the string stability of a one-vehicle look-ahead CACC platoon under different network loss scenarios, and propose to adapt the time headway parameter of the model according to a network reliability metric that we defined based on packet burst loss length to maximize traffic flow efficiency while maintaining a string-stable platoon. Our findings show that careful adjustment of headway value according to the wireless network reliability allows the platoon to maintain string-stable operation while maximizing traffic flow.

Jerk-Limited Time-Optimal Speed Planning for Arbitrary Paths

Both path and speed planning play key roles in automated driving, specially when a certain comfort level is required. This paper proposes a human-like speed planning method for already defined paths while minimizing travel time. The proposed method is able to compute a time-optimal speed profile that meet the given constrains with regard to speed, acceleration and jerk. For this purpose, an initial acceleration-limited approach is introduced. This algorithm serves as a starting point for the subsequent jerk-limited speed planning. Moreover, fallback strategies are included to manage critical driving situations where initial or final conditions cannot be met. The proposed approach has been tested and validated in an experimental platform through extensive trials in real environments. Its performance has been evaluated both in terms of quality of the computed speed profiles and with respect the required computing time.

Deceased donors as nondirected donors in kidney paired donation.

As proof of concept, we simulate a revised kidney allocation system that includes deceased donor (DD) kidneys as chain-initiating kidneys (DD-CIK) in a kidney paired donation pool (KPDP), and estimate potential increases in number of transplants. We consider chains of length 2 in which the DD-CIK gives to a candidate in the KPDP, and that candidate's incompatible donor donates to theDD waitlist. In simulations, we vary initial pool size, arrival rates of candidate/donor pairs and (living) nondirected donors (NDDs), and delay time from entry to the KPDP until a candidate is eligible to receive a DD-CIK. Using data on candidate/donor pairs and NDDs from the Alliance for Paired Kidney Donation, and the actual DDs from the Scientific Registry of Transplant Recipients (SRTR) data, simulations extend over 2years. With an initial pool of 400, respective candidate and NDD arrival rates of 2 per day and 3 per month, and delay times for access to DD-CIK of 6months or less, including DD-CIKs increases the number of transplants by at least 447 over 2years, and greatly reduces waiting times of KPDP candidates. Potential effects on waitlist candidates are discussed as are policy and ethical issues.

FREQUENCY AND DURATION OF OXIMETER DROP-OUTS IN THE NICU: AN OBSERVATIONAL STUDY

Oximeters used for continuous monitoring experience periods with no signal. This SpO2drop-out is widely acknowledged and its causes generally understood. This is a prospectively designed analysis of an existing database with the aim of characterizing drop-outs as experienced in the neonatal ICU. The data reflects 116 days of monitoring in seven tertiary care neonatal ICUs in 6 countries. From the evaluation of 1,396 drop-outs we found that typically the time was minimal with missing SpO2 data, and the episodes were short (median 2.79 minutes per day IQR 0.17-76, median 22 seconds IQR: 15-37, respectively). During during about half of the days there were no prolonged dropouts (1 minute or longer), even so half of the total time spent with no SpO2data were in prolonged episodes (median length 110 seconds IQR 85-150). The predominate factor associated with excessive drop-out time was the number of prolonged episodes rather than their duration. We concluded that the impact of drop-outs during manual control of inspired oxygen primarily impact alarm fatigue, but that during automatic FiO2control they could have an important impact. The relative effectiveness of the fall-back strategies of these automatic control systems ought to be evaluated.

A Fail-Operational Control Architecture Approach and Dead-Reckoning Strategy in Case of Positioning Failures

Presently, in the event of a failure in Automated Driving Systems, control architectures rely on hardware redundancies over software solutions to assure reliability or wait for human interaction in takeover requests to achieve a minimal risk condition. As user confidence and final acceptance of this novel technology are strongly related to enabling safe states, automated fall-back strategies must be assured as a response to failures while the system is performing a dynamic driving task. In this work, a fail-operational control architecture approach and dead-reckoning strategy in case of positioning failures are developed and presented. A fail-operational system is capable of detecting failures in the last available positioning source, warning the decision stage to set up a fall-back strategy and planning a new trajectory in real time. The surrounding objects and road borders are considered during the vehicle motion control after failure, to avoid collisions and lane-keeping purposes. A case study based on a realistic urban scenario is simulated for testing and system verification. It shows that the proposed approach always bears in mind both the passenger’s safety and comfort during the fall-back maneuvering execution.

Hunter–gatherer use of wild plants and domesticates: archaeological implications for mixed economies before agricultural intensification

Much of our success as a species derives from the ability to adapt hunting and gathering to diverse ecologies and incorporate a wide range of food resources. Hunter–gatherers maintain broad dietary options through an array of alternative and fallback strategies. While many decisions facing foragers have been analyzed, few paired nutritional and return rate data are available, especially in relation to the value of wild roots. Ethnoarchaeological data from a group of South American hunter–gatherers allow us to comparatively assess the value of root resources by observing what mobile foragers do when presented with the option to retain or replace wild foods with domesticates. Nutritional content and foraging returns indicate that cultivated tubers provide no clear nutritional or labor advantages. Evidence also does not suggest that wild roots are inferior resources. This may explain why some foragers incorporate domesticates without replacing dependence on wild foods, or signaling a transition to an agrarian economy. This perspective has archaeological implications for modeling of past subsistence during initial and early exploitation of cultigens.

Ecology of culture: do environmental factors influence foraging tool use in wild chimpanzees, Pan troglodytes verus?

Geographical variation in behaviour may be best explained in terms of culture if ecological and genetic explanations can be excluded. However, ecological conditions and genetic predispositions may in turn also affect cultural processes. We examined the influence of environmental factors on foraging tool use among chimpanzees at the Seringbara study site in the Nimba Mountains, Guinea, where nut cracking and termite fishing are absent, but ant dipping is present. We tested two ecological hypotheses to explain foraging tool use prevalence. The opportunity hypothesis states that encounter rates with nuts, insects or tools explain tool use patterns. We measured the density and distribution of nut trees, nuts, army ants, termites and potential tools in relation to the chimpanzees’ ranging patterns. The necessity hypothesis states that tool use is a response to scarcity of preferred foods (i.e. ripe fruit). We measured the temporal availability of nuts, army ants and termites in relation to preferred food sources. Our findings support the opportunity hypothesis: nut trees and Macrotermes mounds were rare and peripheral to the chimpanzees’ range, whereas army ants were abundant and widespread. The necessity hypothesis did not explain tool-assisted insectivory, as both army ants and termites were available during ripe fruit scarcity, yet neither ant dipping nor termite fishing functioned as fallback strategies. Nuts were absent at times of fruit scarcity and were not available as fallback foods. Our findings highlight the importance of considering environmental conditions in explaining foraging tool use by wild chimpanzees and emphasize the interplay between environment and culture.

The Unfinished Revolution: How a New Generation Is Reshaping Family, Work, and Gender in America - by Kathleen Gerson

The Unfinished Revolution: How a New Generation Is Reshaping Family, Work, and Gender in America. Kathleen Gerson. New York: Oxford University Press. 20 10. 297 pp. ISBN: 9780195371673. $24.95 cloth. A new generation's aspirations are never guarantees. Still, each cohort's dreams and fears are a critical barometer of shifting societal conventions and conversations. In Kathleen Gerson's new book The Unfinished Revolution: How a New Generation Is Reshaping Family, Work, and Gender in America, she provides an astute and compelling portrait of how young people today are redrawing crossroads of labor and love. Through an analysis of lifehistory interviews with 120 men and women between ages of 18 and 32, Gerson explores consequences of second-wave feminist revolution on ambitions of its nextgeneration sons and daughters. Two of Gerson's particularly gripping ideas are detailed here: role of gender flexibility in family adaption and growing disconnect between young men and young women's work and family fallback strategies. Gerson's participants grew up during a particularly tumultuous time in history of U.S. gender, economic, and caregiving politics. The late 20th century brought with it movement en masse of American women into workplace and related media fascination, as well as rise of diverse family forms and career patterns. What these young people saw and heard clearly shapes their current disconcerted sense of relationships and careers. Yet experiences of upheaval also provided many participants with an encouraging view of gender flexibility when they saw their parents go against well-tread gendered expectations to meet head-on pragmatic, ever-changing of their families. Throughout Gerson's analysis are threaded stories of divorced motiiers taking on successful breadwinning roles, fathers engaging anew in caregiving, and parents renegotiating gender in midst of crisis. Gerson reflects mat, although many of her participants' families faced economic crises and increasing parental discontent, homes where adults transgressed gender boundaries in breadwinning and parenting were better equipped to meet a child's economic and emotional needs (p. 216). One lesson Gerson draws for us - as scholars of family and everyday family members - is that we need to move away from our absorption on static family forms to more fully deliberate on varieties of family processes and pathways; she illustrates so well that the starting point does not determine destination (p. 215). Seeing positive effects of gender flexibility, for this generation, may serve to further loosen gender's grip on work and family life in decades to come. And for this generation of family scholars, seeing that static labels such as single parent or dual-earner household are often only temporary characterizations, not fixed categorizations, can help us focus on exploring ways families adapt to and take part in changing economic, relational, and gendered circumstances. Gender flexibility gives us one way to think about power of individually crossing gendered work and family boundaries, but this process, according to Gerson, is certainly not an easy or guaranteed course of action for this next generation. Individual and relational adjustment does not negate realities of unforgiving work structures, greedy institutions, and economic recessions. As such, fallback strategies are also central to Gerson's analysis. Most of her participants aspire to loving, committed, and equal partnerships and to rewarding and financially sustaining work lives. Yet facing an unsure future, children of gender revolution often express need to formulate backup plans or contingency strategies to compose a successful life. And new challenges, as we know, usually accompany new opportunities. Equal caregiving and wage earning in long-term relationships are ideal work and family aspirations for most young women whom Gerson interviewed; nonetheless, these women also anticipate or have already experienced necessity for a backup plan. …

Fallback foods and dietary partitioning among Pan and gorilla

Recent findings on the strong preference of gorillas for fruits and the large dietary overlap between sympatric gorillas and chimpanzees has led to a debate over the folivorous/frugivorous dichotomy and resource partitioning. To add insight to these arguments, we analyze the diets of sympatric gorillas and chimpanzees inhabiting the montane forest of Kahuzi-Biega National Park (DRC) using a new definition of fallback foods (Marshall and Wrangham: Int J Primatol 28 [2007] 1219-1235). We determined the preferred fruits of Kahuzi chimpanzees and gorillas from direct feeding observations and fecal analyses conducted over an 8-year period. Although there was extensive overlap in the preferred fruits of these two species, gorillas tended to consume fewer fruits with prolonged availability while chimpanzees consumed fruits with large seasonal fluctuations. Fig fruit was defined as a preferred food of chimpanzees, although it may also play a role as the staple fallback food. Animal foods, such as honey bees and ants, appear to constitute filler fallback foods of chimpanzees. Tool use allows chimpanzees to obtain such high-quality fallback foods during periods of fruit scarcity. Among filler fallback foods, terrestrial herbs may enable chimpanzees to live in small home ranges in the montane forest, whereas the availability of animal foods may permit them to expand their home range in arid areas. Staple fallback foods including barks enable gorillas to form cohesive groups with similar home range across habitats irrespective of fruit abundance. These differences in fallback strategies seem to have shaped different social features between sympatric gorillas and chimpanzees.

Summary to the symposium issue: Primate fallback strategies as adaptive phenotypic plasticity—Scale, pattern, and process

In this discussion, I evaluate our understanding of fallback foods in primate and hominin ecology and evolution with reference to the challenges of nomenclature, scale, and of linking individual responses to food availability and properties (process) to species traits (pattern). I use these challenges to form the framework of my discussion and ultimately conclude that we situate the discussion of primate fallback strategy into a broader, "synthetic" framework of animal form and the evolutionary significance of phenotypic plasticity.

Chapter Three: Can Iran's Capability Be Kept Non-Weaponised?

This paper explains how Iran developed its nuclear programme to the point where it threatens to achieve a weapons capability within a short time frame, and analyses Western policy responses aimed at forestalling that capability. Key questions are addressed: will the world have to accept an Iranian uranium enrichment programme, and does having a weapons capability mean having the Bomb? For nearly two decades, Western strategy on the Iran nuclear issue emphasised denial of supply. Since 2002, there has also been a demand-side dimension to the strategy, aimed at changing Iran's cost–benefit calculations through inducements and pressure. But the failure of these policies to prevent Iran from coming close to achieving a nuclear-weapons capability has promoted suggestions for fallback strategies that would grant legitimacy to uranium enrichment in Iran in exchange for intrusive inspections and constraints on the programme. The paper assesses these ‘second-best’ options in terms of their feasibility and their impact on the proliferation risks of diversion of nuclear material and knowledge, clandestine development and NPT break-out, and the risk of stimulating a proliferation cascade in the Middle East and beyond. It concludes that the risks are still best minimised by reinforcing the binary choice presented to Iran of cooperation or isolation, and strengthening denial of supply.

Chapter Two: Western Strategy So Far

This paper explains how Iran developed its nuclear programme to the point where it threatens to achieve a weapons capability within a short time frame, and analyses Western policy responses aimed at forestalling that capability. Key questions are addressed: will the world have to accept an Iranian uranium enrichment programme, and does having a weapons capability mean having the Bomb? For nearly two decades, Western strategy on the Iran nuclear issue emphasised denial of supply. Since 2002, there has also been a demand-side dimension to the strategy, aimed at changing Iran's cost–benefit calculations through inducements and pressure. But the failure of these policies to prevent Iran from coming close to achieving a nuclear-weapons capability has promoted suggestions for fallback strategies that would grant legitimacy to uranium enrichment in Iran in exchange for intrusive inspections and constraints on the programme. The paper assesses these ‘second-best’ options in terms of their feasibility and their impact on the proliferation risks of diversion of nuclear material and knowledge, clandestine development and NPT break-out, and the risk of stimulating a proliferation cascade in the Middle East and beyond. It concludes that the risks are still best minimised by reinforcing the binary choice presented to Iran of cooperation or isolation, and strengthening denial of supply.

Conclusion

This paper explains how Iran developed its nuclear programme to the point where it threatens to achieve a weapons capability within a short time frame, and analyses Western policy responses aimed at forestalling that capability. Key questions are addressed: will the world have to accept an Iranian uranium enrichment programme, and does having a weapons capability mean having the Bomb? For nearly two decades, Western strategy on the Iran nuclear issue emphasised denial of supply. Since 2002, there has also been a demand-side dimension to the strategy, aimed at changing Iran's cost–benefit calculations through inducements and pressure. But the failure of these policies to prevent Iran from coming close to achieving a nuclear-weapons capability has promoted suggestions for fallback strategies that would grant legitimacy to uranium enrichment in Iran in exchange for intrusive inspections and constraints on the programme. The paper assesses these ‘second-best’ options in terms of their feasibility and their impact on the proliferation risks of diversion of nuclear material and knowledge, clandestine development and NPT break-out, and the risk of stimulating a proliferation cascade in the Middle East and beyond. It concludes that the risks are still best minimised by reinforcing the binary choice presented to Iran of cooperation or isolation, and strengthening denial of supply.

Chapter One: Framing the Problem: Iran's Pursuit of Fissile Material

This paper explains how Iran developed its nuclear programme to the point where it threatens to achieve a weapons capability within a short time frame, and analyses Western policy responses aimed at forestalling that capability. Key questions are addressed: will the world have to accept an Iranian uranium enrichment programme, and does having a weapons capability mean having the Bomb? For nearly two decades, Western strategy on the Iran nuclear issue emphasised denial of supply. Since 2002, there has also been a demand-side dimension to the strategy, aimed at changing Iran's cost–benefit calculations through inducements and pressure. But the failure of these policies to prevent Iran from coming close to achieving a nuclear-weapons capability has promoted suggestions for fallback strategies that would grant legitimacy to uranium enrichment in Iran in exchange for intrusive inspections and constraints on the programme. The paper assesses these ‘second-best’ options in terms of their feasibility and their impact on the proliferation risks of diversion of nuclear material and knowledge, clandestine development and NPT break-out, and the risk of stimulating a proliferation cascade in the Middle East and beyond. It concludes that the risks are still best minimised by reinforcing the binary choice presented to Iran of cooperation or isolation, and strengthening denial of supply.

Notes

This paper explains how Iran developed its nuclear programme to the point where it threatens to achieve a weapons capability within a short time frame, and analyses Western policy responses aimed at forestalling that capability. Key questions are addressed: will the world have to accept an Iranian uranium enrichment programme, and does having a weapons capability mean having the Bomb? For nearly two decades, Western strategy on the Iran nuclear issue emphasised denial of supply. Since 2002, there has also been a demand-side dimension to the strategy, aimed at changing Iran's cost–benefit calculations through inducements and pressure. But the failure of these policies to prevent Iran from coming close to achieving a nuclear-weapons capability has promoted suggestions for fallback strategies that would grant legitimacy to uranium enrichment in Iran in exchange for intrusive inspections and constraints on the programme. The paper assesses these ‘second-best’ options in terms of their feasibility and their impact on the proliferation risks of diversion of nuclear material and knowledge, clandestine development and NPT break-out, and the risk of stimulating a proliferation cascade in the Middle East and beyond. It concludes that the risks are still best minimised by reinforcing the binary choice presented to Iran of cooperation or isolation, and strengthening denial of supply.

Centralized Monitoring for Vehicle Dynamics Sensor Networks

An increasing number of control systems in modern automotive vehicles is based on measurements of signals describing vehicle dynamics. Correspondingly, a large number of sensors is required. To spare on weight and even more important on costs, car manufacturers require joint processing of sensors, i.e. the individual sensors related to certain control systems should become part of a sensor network. In the paper at hand the possibilities and shortcomings of such an approach are examined from a sensor monitoring and estimation perspective. Especially, redundant and model based failure detection are considered. The focus is on signals and sensors related to vehicle dynamics and the corresponding question of fall back strategies in case of sensor failure. Corresponding problems are addressed with the introduction of a new sensor network architecture.

Negotiating Turkey's Membership to the European Union. Can the Member States Do As They Please?

Limits to member states' discretion in European Union enlargement negotiations – Changing the fundamentals of the EU constitutional order through the conclusion of accession treaties – The case of Turkey – Caveats, precautions and fallback strategies in the ‘Negotiating Framework for Turkey’ – Enforcing the limits to member states' discretion in European Union enlargement negotiations – The jurisdiction of the European Court of Justice before ratification and after entry into force.