Framework Of Constraints Research Articles

How Are Emergent Constraints Quantifying Uncertainty and What Do They Leave Behind?

AbstractThe use of emergent constraints to quantify uncertainty for policy-relevant quantities such as equilibrium climate sensitivity (ECS) has become increasingly widespread in recent years. Many researchers, however, claim that emergent constraints are inappropriate or even underreport uncertainty. In this paper we contribute to this discussion by examining the emergent constraints methodology in terms of its underpinning statistical assumptions. We argue that the statistical assumptions required to underpin existing frameworks are strong, hard to defend, and lead to an underreporting of uncertainty. We show how weakening them leads to a more transparent Bayesian framework wherein hitherto-ignored sources of uncertainty, such as how reality might differ from models, can be quantified. We present a guided framework for the quantification of additional uncertainties that is linked to the confidence we can have in the underpinning physical arguments for using linear constraints. We provide a software tool for implementing our framework for emergent constraints and use it to illustrate the methods on a number of recent emergent constraints for ECS. We find that the robustness of any constraint to additional uncertainties depends strongly on the confidence we have in the underpinning physics, allowing a future framing of the debate over the validity of a particular constraint around underlying physical arguments, rather than statistical assumptions. We also find that when physical arguments lead to confidence in the linear relationships underpinning emergent constraints, prediction intervals are only slightly widened by including additional uncertainties, and they show this across a range of emergent constraints for ECS.

Scenarios in the strategy process: a framework of affordances and constraints

This paper challenges the solely rational view of the scenario technique as a strategy and foresight tool designed to cope with uncertainty by considering multiple possible future states. The paper employs an affordance-based view that allows for the identification and structuring of hidden, emergent attributes of the scenario technique beyond the intended ones. The suggested framework distinguishes between affordances (1) that are intended by the organization and relate to its goals, (2) that emergently generate organizational benefits, and (3) that do not relate to organizational but individual interests. Also, constraints in the use of scenarios are discussed. Affordance theory’s specific lens shows that the emergence of such attributes depends on the users’ specific intentions.

High-Resolution Optical Remote Sensing Image Registration via Reweighted Random Walk Based Hyper-Graph Matching

High-resolution optical remote sensing image registration is still a challenging task due to non-linearity in the intensity differences and geometric distortion. In this paper, an efficient method utilizing a hyper-graph matching algorithm is proposed, which can simultaneously use the high-order structure information and radiometric information, to obtain thousands of feature point pairs for accurate image registration. The method mainly consists of the following steps: firstly, initial matching by Uniform Robust Scale-Invariant Feature Transform (UR-SIFT) is carried out in the highest pyramid image level to derive the approximate geometric relationship between the images; secondly, two-stage point matching is performed to find the matches, that is, a rotation and scale invariant area-based matching method is used to derive matching candidates for each feature point and an efficient hyper-graph matching algorithm is applied to find the best match for each feature point; thirdly, a local quadratic polynomial constraint framework is used to eliminate match outliers; finally, the above process is iterated until finishing the matching in the original image. Then, the obtained correspondences are used to perform the image registration. The effectiveness of the proposed method is tested with six pairs of high-resolution optical images, covering different landscape types—such as mountain area, urban, suburb, and flat land—and registration accuracy of sub-pixel level is obtained. The experiments show that the proposed method outperforms the conventional matching algorithms such as SURF, AKAZE, ORB, BRISK, and FAST in terms of total number of correct matches and matching precision.

Search for new physics in top quark production in dilepton final states in proton-proton collisions at sqrt{s} = 13,text {TeV}

A search for new physics in top quark production is performed in proton-proton collisions at 13,text {TeV} . The data set corresponds to an integrated luminosity of 35.9{,text {fb}^{-1}} collected in 2016 with the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons), and mathrm{b} quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a mathrm{W} boson. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of effective field theory and constraints on the relevant effective couplings are set, one at a time, using a dedicated multivariate analysis. This analysis differs from previous searches for new physics in the top quark sector by explicitly separating mathrm{t}mathrm{W} from mathrm{t}{bar{mathrm{t}}} events and exploiting the specific sensitivity of the mathrm{t}mathrm{W} process to new physics.

Solving bi-objective uncertain stochastic resource allocation problems by the CVaR-based risk measure and decomposition-based multi-objective evolutionary algorithms

This paper investigates the uncertain stochastic resource allocation problem in which the results of a given allocation of resources are described as probabilities and these probabilities are considered to be uncertain from practical aspects. Here uncertainties are introduced by assuming that these probabilities depend on random parameters which are impacted by various factors. The redundancy allocation problem (RAP) and the multi-stage weapon-target assignment (MWTA) problem are special cases of stochastic resource allocation problems. Bi-objective models for the uncertain RAP and MWTA problem in which the conditional value-at-risk measure is used to control the risk brought by uncertainties are presented in this paper. The bi-objective formulation covers the objectives of minimizing the risk of failure of completing activities and the resulting cost of resources. With the aim of determining referenced Pareto fronts, a linearized formulation and an approximated linear formulation are put forward for RAPs and MWTA problems based on problem-specific characteristics, respectively. Two state-of-the-art decomposition-based multi-objective evolutionary algorithms (i.e., MOEA/D-AWA and DMOEA- $$\varepsilon \hbox {C}$$ ) are used to solve the formulated bi-objective problem. In view of differences between MOEA/D-AWA and DMOEA- $$\varepsilon \hbox {C}$$ , two matching schemes inspired by DMOEA- $$\varepsilon \hbox {C}$$ are proposed and embedded in MOEA/D-AWA. Numerical experiments have been performed on a set of uncertain RAP and MWTA instances. Experimental results demonstrate that DMOEA- $$\varepsilon \hbox {C}$$ outperforms MOEA/D-AWA on the majority of test instances and the superiority of DMOEA- $$\varepsilon \hbox {C}$$ can be ascribed to the $$\varepsilon $$ -constraint framework.

Outage probability and ergodic capacity analysis of uplink NOMA cellular network with and without interference from D2D pair

We consider the framework of uplink transmission and interference constraint for new system model to provide multiple access scheme for fifth generation (5G) wireless communications. In particular, such considered system contains normal cellular users deploying a non-orthogonal multiple access (NOMA) scheme and underlay device-to-device (D2D) users deploying traditional orthogonal multiple access (OMA). Such potentials motivate us consider uplink in cellular network in which the base station (BS) is required to fulfill two NOMA users’ diverse quality of service (QoS) requests under location arrangement with nearby D2D user pair. With regard to enhanced successive interference cancellation (SIC) scheme, the BS still performs the signal detection of NOMA users based on the decoding order and even though existence of an extra interference from D2D user pair. In term of quality evaluation, the ergodic capacity and outage probability are two underlying metrics need be investigated systematically. As important results, detailed derivations are provided in a scenario that considering coexistence of D2D users and NOMA users. As extended scenario, multiple antenna NOMA users exhibit improved performance and the related comparisons are provided. Finally, simulations in various scenarios are conducted to corroborate the precision of the mathematically derivations and to confirm potential of deployment in NOMA with SIC operation.

Antimicrobial Coatings for Food Contact Surfaces: Legal Framework, Mechanical Properties, and Potential Applications.

Food contact surfaces (FCS) in food processing facilities may become contaminated with a number of unwanted microorganisms, such as Listeria monocytogenes, Escherichia coli O157:H7, and Staphylococcus aureus. To reduce contamination and the spread of disease, these surfaces may be treated with sanitizers or have active antimicrobial components adhered to them. Although significant efforts have been devoted to the development of coatings that improve the antimicrobial effectiveness of FCS, other important coating considerations, such as hardness, adhesion to a substrate, and migration of the antimicrobial substance into the food matrix, have largely been disregarded to the detriment of their translation into practical application. To address this gap, this review examines the mechanical properties of antimicrobial coatings (AMC) applied to FCS and their interplay with their antimicrobial properties within the framework of relevant regulatory constraints that would apply if these were used in real-world applications. This review also explores the various assessment techniques for examining these properties, the effects of the deposition methods on coating properties, and the potential applications of such coatings for FCS. Overall, this review attempts to provide a holistic perspective. Evaluation of the current literature urges a compromise between antimicrobial effectiveness and mechanical stability in order to adhere to various regulatory frameworks as the next step toward improving the industrial feasibility of AMC for FCS applications.

A Conceptual Framework of Ethical Considerations and Legal Constraints in the Algorithm-Driven Pricing Function

The extent to which pricing executives consider consumer perceptions of deception, fairness, and social justice is positioned within an emerging area of research that triangulates the dynamic between legal constraints, ethical considerations, and algorithmic models to make pricing decisions. This paper builds a conceptual model from an analysis of literature describing how companies couple organizational and technology factors into the price-setting process. The legal frameworks of antitrust, data privacy, and antidiscrimination are tethered to the ethical frameworks of deception, fairness, and social justice to form a foundation of relevant organizational factors. A qualitative study is proposed to test the validity of the conceptual model. The primary contribution of this paper is to catalyze practitioner discussion and spur empirical research into the implications of personalized pricing using algorithmic models.

Methods of the automated aircraft configuration

Aircraft are great and comprehensive technical systems, which are characterised by the great configuration density. This article presents formation of the geometrical conceptual design of the aircraft on the basis of the formal heuristic procedures within the framework of the infrastructural constraints. In addition, this article includes description of influence of the aerodynamic configuration and the volume-weight configuration upon formation of the geometrical conceptual design of the aircraft, as well as description of other mass/inertia characteristics of the aggregates, which are to be installed within the specific aircraft. This article also states that in the case of the "very strict" infrastructural constraints, it is necessary to solve "the inverse" problem of configuration, that is the problem, where initial data for formation of the geometrical conceptual design of the aircraft are determined by the necessary configuration space, which is determined by the infrastructural constraints. The article presents the project problem (in aggregate) of finding rational values for parameters of the geometrical conceptual design of the aircraft as the problem of the multiple criteria discrete optimisation. This article states that it is possible to formulate this problem as the search of the vector of structural parameters (that is, search of the multitude of the admissible alternatives of the drawing and designing solutions).

Stability analysis and output-feedback synthesis of hybrid systems affected by piecewise constant parameters via dynamic resetting scalings

We develop novel criteria for robust stability of a class of hybrid systems that are affected by piecewise constant uncertain parameters with dwell-time constraints. These criteria result from clock-dependent Lyapunov arguments that are based on several new robust stability conditions for continuous-time linear time-invariant systems which are affected by parametric passive uncertainties and do not admit any discrete dynamics. In contrast to other approaches, our stability analysis results rely on separation techniques from robust control involving dynamic resetting scalings. Moreover, these techniques are expected to pave the way for covering much more general uncertainties within the framework of integral quadratic constraints. Building upon the new insights on robust stability, we are able to propose an output-feedback gain-scheduling design methodology similarly to our recently obtained synthesis result involving dynamic resetting D-scalings. Most of the obtained conditions are expressed as infinite-dimensional (differential) linear matrix inequalities which can be numerically solved by using relaxation methods based on, e.g., linear splines or matrix sum-of-squares. We apply our results to obtain novel stability criteria and to design distributed controllers for networked systems over undirected switching topologies. Finally, the approach is illustrated with several numerical examples.

Fiscal Sustainability in the Caribbean: An Econometric Analysis

Many countries in the Caribbean have been grappling with persistent fiscal imbalances and rising debt levels. The average debt to GDP ratio in the Caribbean in 2017 was 76.6 percent, higher than the negative debt-growth threshold of 60 percent of GDP. Also, the average fiscal deficit as a percent of GDP was 2.8 percent, but with significant heterogeneity across countries ranging from 0.5 percent to 11 percent. Using the inter-temporal budget constraint framework and various panel data econometric estimators, this article examines the issue of fiscal sustainability for a group of 10 Caribbean countries over the period 1991-2017. The evidence from panel cointegration models of government revenue and expenditure shows that past fiscal behavior is “weakly” sustainable. The “weak sustainability” finding is reinforced by evidence from an extended fiscal reaction function which showed that the primary balance improves by about 0.02 for every 1 percentage point increase in the debt ratio.

Digitisation, Copyright and the Glam Sector: Constructing a Fit-For-Purpose Safe Harbour Regime

Copyright law does not currently align with the legitimate activities of galleries, libraries, archives and museums (GLAMs). The GLAM sector plays a central role in collecting and promoting access to cultural works. Increasingly, GLAM institutions are employing innovative digital technologies to expand access to culture and foster greater levels of cultural participation. Despite the utility underlying digitisation, copyright limits the use of digital technologies within the GLAM sphere. This article examines current copyright limitations and demonstrates copyright's significant limiting effect. It argues that reform is necessary to strengthen the right to participate in cultural life and to remedy harms inflicted by the current copyright regime. Creating a fit-for-purpose safe harbour would empower institutions to employ digitisation within a framework of reasonable copyright constraints. Accordingly, this article constructs a potential safe harbor that permits non-commercial GLAM digitisation, while also protecting copyright holders and tikanga Māori. The Copyright Act 1994 is currently under review. New Zealand ought to seize the present reform opportunity to invigorate participation in cultural life and enrich the cultural fabric of society.

Assistive Exoskeleton Control with User-Tuned Multi-Objective Optimization.

Assistive exoskeletons that utilize trajectory following control have been shown to produce stable gait for users. These however, do not allow intuitive tuning to customize gait to users' preferences. When persons walk on their own, they balance a variety of needs such as speed, comfort, and energy. Providing user tuning by optimizing between different gait performance measures gives an intuitive flexibility. We have shown the optimization between natural walking and gait energy produces stable bipedal gait through simulation in a virtual constraint framework. This verification shows validity of the methodology and framework for improving tuning and customization of assistive exoskeletons.

No interest, no time! Gendered constraints to museum visits in Flanders

This paper investigates why non-attendees of museums in Flanders (Belgium) do not visit and how these reasons for not attending are related to gender. The hierarchical constraints framework is applied to non-attendees using the 2014 Participation Survey (N = 2707). Both interested and non-interested non-attendees are included in the analyses. Findings reveal that interest constraints are the greatest barrier for museum visits for both women and men. However, men do report this type of constraint more than women. Women, on the other hand, report more interpersonal and structural constraints. Older women seem doubly disadvantaged regarding interpersonal constraints, and women with a lower subjective income are doubly disadvantaged for both interpersonal and structural constraints. This paper explains discrepancies in the experiences of constraints between different groups by the hierarchy of social privilege, referring to the role of socialization and culture in influencing people’s preferences. Evaluating the constraint model in research regarding cultural participation, the paper proposes a clarification based on Parsons’ action theory framework.

Temporal Constraints in Human--Building Interaction

Human--building interaction (HBI) is converging the fields of architecture and interaction design, leading to new and interesting tensions in perspectives and methodological approaches. One such tension is related to temporal constraints. Architecture and interaction design typically produce outcomes with very different lifetime expectancies and, predominantly, use methods with very different pace. As an example, fast, iterative approaches of contemporary interaction design, consisting of frequent updates and redesigns, contrasts with much slower, plan-driven and long-term vision driven approaches within architecture. One question emerging from this tension is how to meaningfully combine perspectives and approaches. One suggestion, among others, has been that interaction design methods such as participatory design can be used to heighten the involvement of inhabitants and other stakeholders in continuous adaptations of the buildings they inhabit. While an interesting proposal, we believe that methodological considerations only partly address the complexity of the tension at play from the different lifetime expectancies of buildings and interactive computer systems. Unfolding this complexity further, we therefore propose a framework of temporal constraints at three levels of abstraction: (1) rationale, (2) method, and (3) outcome. Inspired by previous work, we discuss temporal constraints in HBI at these levels. We argue that designing for HBI requires an understanding of temporally constrained design conventions that apply meaningfully to both the short term and long term.

Finite‐time boundedness of large‐scale systems with actuator faults and gain fluctuations

SummaryThis paper addresses the issue of finite‐time boundedness of large‐scale interconnected systems with the use of a distributed nonfragile fault‐tolerant controller. The objective of this paper is to design a state‐feedback controller consisting of a time‐varying delay such that the resulting closed‐loop system is finite‐time bounded under a prescribed extended passivity performance level even in the presence of all admissible uncertainties and possible actuator faults. More precisely, based on the Lyapunov‐Krasovskii stability theory, a new set of sufficient conditions is obtained in the framework of linear matrix inequality constraints that ensures finite‐time boundedness and satisfies the prescribed extended passivity performance index of the considered system. Finally, two numerical examples, including the interconnected inverted pendulum, are given to show the effectiveness of the proposed controller design technique.

Assessment of techno-economic benefits for smart charging scheme of electricvehicles in residential distribution system

Connecting multiple electric vehicles (EVs) to a power system network for the purpose of charging has major setbacks like decrease in power quality, instability in voltage profile, and increase in power losses and thus electricity price. This paper focuses on devising an optimal charging scheme to reduce the negative impacts of EVs' presence in the distribution network by limiting the charging process to only off-peak demand periods when the electricity price is comparatively lower. The salp swarm algorithm, an efficient, fast, and reliable optimization technique, is used to obtain the optimal locations for the EVs and their charging schedule in a residential 107-bus radial distribution system (RDS). The proposed optimization technique minimizes the total charging cost of the EVs within the framework of operational constraints of a residential RDS and parking availability. This charging scheme takes care of benefit maximization from both consumer and power supply operators' perspectives by controlling the starting time of EV charging as well as the EV charging rate in order to arrive at the objective.

Land Stewardship and Freshwater Outcomes: An Overview of Practice and Results

This special issue of the Natural Areas Journal focuses on the stewardship of protected landscapes for the benefit of freshwater quality and quantity and for aquatic ecosystem integrity. Land stewardship, the responsible use and care of natural lands and ecological resources, can be done in ways that enhance, or at least avoid harming, connected aquatic ecosystems and the people that depend upon the renewable goods and services provided by fresh waters. There is a critical need for a compendium of current science on the effects of various land stewardship practices on freshwater ecosystems, to guide the planning and implementation of on-the-ground stewardship activities, identify knowledge gaps for research scientists, provide funders of land stewardship activities with knowledge that can be applied to the evaluation of grant proposals and project outcomes, and offer the scientific evidence underlying the most efficient and effective practices to decision makers involved in developing and amending conservation policy. Our objectives with this special issue are to further the process of compiling the relevant science and encourage those involved in conservation land management to automatically and routinely consider the effects of their practices on water quality and quantity.The benefits of protected natural areas to freshwater quality and quantity and aquatic ecosystem integrity are indisputable, but how those protected lands are managed has a strong influence on the degree of benefit. Stewardship practices in riparian areas, floodplains, and other locations near surface waters have the greatest influence on freshwater resources. When done judiciously and based on current scientific understanding, they can reduce or eliminate excessive inputs of sediment, nutrients, pathogens, organic matter, and pollutants to fresh waters by minimizing disturbance to soils and to the soil-protecting and soil-building functions of vegetation. The challenges are not simply identifying the current best stewardship practices, but also include deciding among competing management goals and priorities; putting effective incentives in place (and amending or avoiding perverse incentives) for implementation of conservation practices; succeeding within a framework of social, political, and economic constraints; and acting effectively despite considerable uncertainty. This overview and the other papers in this special issue report recent advances in the environmental sciences, and also the science of human behavior, that will be pivotal for land stewards as they take into consideration the freshwater consequences of their actions.

Small-Scale Apple Farmers' Willingness to Invest - the Case of Korça Region Farmers in Albania

In this study we aim at assessing the willingness to invest of small‑apple farms in Korça region‑Albania. Furthermore, we want to identify and assess what are major determinants, as percept by farmers’, willingness to invest. To this purpose we used data collected through face‑to‑face interviews with apple farmers. We used descriptive statistics, as well as classical and multinomial logistic regression. Most of farmers are willing to invest in view of their positive expectations for investment climate. Other important factors of willingness to invest are access to loans, advisory extension services, market competition, willingness to cooperate and willingness to take loans, and farm income, while socio‑demographic factors such as age, education, and farming experience do not have significant effect on willingness to invest. Large farms are generally more willing to invest. We present also a general framework of constraints and policy levers to improving the investment climate which is almost valid also for Albania. Improving farmers’ access to private credit sources, policy stability, providing information and public advisory services to small farmers, support farmers to adopt new technology, support to the creation of farmers’ formal and informal groups, and mitigate risks of various type are some but essential policy measures to motivate farmers to invest more in apple.

Joint Power Spectrum and Voxel Intensity Distribution Forecast on the CO Luminosity Function with COMAP

Abstract We develop a framework for joint constraints on the CO luminosity function based on power spectra (PS) and voxel intensity distributions (VID) and apply this to simulations of CO Mapping Array Pathfinder (COMAP), a CO intensity mapping experiment. This Bayesian framework is based on a Markov chain Monte Carlo (MCMC) sampler coupled to a Gaussian likelihood with a joint PS + VID covariance matrix computed from a large number of fiducial simulations and re-calibrated with a small number of simulations per MCMC step. The simulations are based on dark matter halos from fast peak patch simulations combined with the L CO(M halo) model of Li et al. We find that the relative power to constrain the CO luminosity function depends on the luminosity range of interest. In particular, the VID is more sensitive at large luminosities, while the PS and the VID are both competitive at small and intermediate luminosities. The joint analysis is superior to using either observable separately. When averaging over CO luminosities ranging between , and over 10 cosmological realizations of COMAP Phase 2, the uncertainties (in dex) are larger by 58% and 30% for the PS and VID, respectively, when compared to the joint analysis (PS + VID). This method is generally applicable to any other random field, with a complicated likelihood, as long a fast simulation procedure is available.