Extension Problem Research Articles

Material selection and conceptual design in natural fibre composites

Abstract Material selection is the process of determining which material is best suited to meet the needs of a specific application. Mechanical characteristics, chemical properties, physical properties, electrical properties, and cost are all aspects that define the selection requirements. During the material selection process, these must be weighed. Materials selection is a process used by design engineers to choose the best materials for a specific component. To find the best composite materials, a materials selection system is used to find candidate materials from various composite materials that meet all of the material selection criteria, such as strength, stiffness, cost, and aesthetics. Similarly, a materials selection system will require candidate materials to contain several forms of NFC to identify the best appropriate NFC for a specific product. Materials selection for NFC goods is a relatively recent field of study. Because of the vast number of individual constituent materials in NFC, the work of selecting the best NFC for a specific product is regarded as challenging and time-intensive (Marques T, Esteves JL, Viana J, Loureiro N, Arteiro A. Design for sustainability with composite systems. In: 15th international conference on experimental mechanics (ICEM15); 2012:1–2 pp). Whereas conceptual design is a crucial activity in the design process in modern design, it is continually highlighted that improper conceptual design can lead to extensive rework and problems after the product is produced. According to (Pugh S. Total design: integrated methods for successful product engineering. Wokingham, England: Addison-Wesley Publishing; 1991), conceptual design activity is creating and assessing design solutions to meet the PDS. Because many design features are distinct in composites, and the tailor-made nature of composites has caused the design approach to be different, conceptual design with NFC is typically different from metals. Designing with NFC is similar to designing with a traditional composite product in terms of concept. This activity entails numerous processes, including creating a design brief, information collecting, market research, and product design specifications (PDS).

An efficient global optimization algorithm for expensive constrained black-box problems by reducing candidate infilling region

Surrogate-based optimization methods are usually employed to solve expensive black-box optimization problems. Constraints bring more challenges for optimization than unconstrained problems. This study proposes a novel three-stage infilling framework to solve expensive single-objective problems with equality and/or inequality constraints. In the first stage, a criterion for locating a feasible region is designed. Until a feasible solution is found, the first stage is removed in the subsequent process. The second stage exploits the current best feasible solution and explores potentially better solutions. If the infilled site is infeasible, the third stage will proceed to improve the surrogate accuracy around the feasible region boundary and an extra constraint derived from the objective is proposed to reduce the candidate infill region in this stage. Otherwise, the process stays in stage two. Stage two continues once one third-stage point has been sampled. For brevity, the three-stage framework is called CEGO-DI. The efficacy of CEGO-DI is demonstrated by comparing it with two variants of it. In addition, the method is also compared with several state-of-the-art algorithms on extensive problems. The experimental results show that CEGO-DI has a better or competitive performance on most problems.

Finding the Community’s Voice: Community-Based Participatory Research in Three Iowa Counties

Engaging all Iowans in building a stronger state, preparing for a thriving future, and solving contemporary problems in research, education, and extension are central to the mission and vision of Iowa State University Extension and Outreach (EO). Achieving these goals will hinge upon EO’s ability to innovate and respond to the needs and interests of Iowa’s diverse residents. Similar to other rural states, the composition of Iowa’s population is evolving in terms of race, nationality, economics, and education. The identities of EO staff do not reflect the communities EO is committed to serving; therefore, programming and activities may lack cultural relevance. In three small studies, Iowa State faculty and research assistants, EO staff, and community consultants (CCs) collaboratively organized local “study circles” and “action forums” in an effort to better understand underrepresented families’ needs in three Iowa counties. The team recruited 98 adults and youth to participate in these group discussions. Often, participants were not aware of EO’s mission, logo, or programs and services. Residents offered ideas for fostering familiarity, trust, and connection. CCs also listened to residents’ barriers to engagement, such as program formats and topics, and documented useful resources to enhance accessibility. Participants shared ideas for programs that they would be motivated to engage in. In this article, the authors outline connections to prior work, recommendations, and limitations.

Sense or sensibility-Ideological dilemmas in gamblers' notions of responsibilities for gambling problems.

The gambling market is a complex field of conflicting stakeholders and interests involving dimensions, such as economy, health, social inequality and morals. The division of responsibility between gamblers, the gambling industry and the regulating state for limiting the harmful effects of this activity, however, are unclear. The aim of this study was to explore how gamblers in the Swedish market attribute responsibility to various actors within the gambling field. Qualitative interviews were conducted with 37 gamblers experiencing extensive gambling problems. Based on a discourse analytical approach, five ideological dilemmas were identified, highlighting the tension between the, often contradictory, values that the participants need to relate to. On the individual level, the gamblers emphasize their own responsibility for their problem, thereby showing accountability in relation to themselves, their significant others and their peers as agents in recovery. On the corporate- and state levels however, the participants argue for a stronger public health approach, where the gambling companies should take further responsibility by living up to the legal regulations and where the state should ensure compliance and safeguard funding for treatment and research. The essential paradox between the individual responsibility discourse of self-regulation and the prevailing medical discourse of the gambler's incapacity for self-control signifies an impossible equation that imposes feelings of guilt and shame upon an individual who is concurrently considered as both responsible and incapable. In order to reduce harm, the gambling industry must be more proactive with coercive external control measures to fulfill the duty of care they claim to adhere to, and the regulating state must ensure its compliance.

Smooth selection for infinite sets

Whitney's extension problem asks the following: Given a compact set E⊂Rn and a function f:E→R, how can we tell whether there exists F∈Cm(Rn) such that F=f on E? A 2006 theorem of Charles Fefferman [6] answers this question in its full generality.In this paper, we establish a version of this theorem adapted for variants of the Whitney extension problem, including nonnegative extensions and the smooth selection problems. Among other things, we generalize the Finiteness Principle for smooth selection by Fefferman-Israel-Luli [9] to the setting of infinite sets.Our main result is stated in terms of the iterated Glaeser refinement of a bundle formed by taking potential Taylor polynomials at each point of E. In particular, we show that such bundles (and any bundles with closed, convex fibers) stabilize after a bounded number of Glaeser refinements, thus strengthening the previous results of Glaeser, Bierstone-Milman-Pawłucki, and Fefferman which only hold for bundles with affine fibers.

A Numerical Study on the Crack Propagation of Homogenized Micro-Crack Crushing for Concrete Pavement

Homogenized micro-crack crushing is a new method of concrete pavement rehabilitation that makes full use of the bearing capacity of the original concrete pavement, whereby the treated pavement can be directly overlaid with hot mixed asphalt concrete. In order to solve the problem of longitudinal crack extension of a cracked core in the weak position of local pavement, the crack propagation mode of concrete slabs under low-velocity impact from different numbers and distributions of impact heads was studied using numerical simulation. Moreover, field tests were also carried out to determine the optimal layout of drop hammer impact heads, and the numerical simulation results were compared with the experimental data. The results show that, when a concrete slab is impacted by a single impact head, the bottom of the slab first cracks and then the crack develops upward until the main crack runs through the concrete slab. However, when the concrete slab is impacted by multiple-impact heads, including three or four impact heads, the concrete slab forms a triangular or quadrilateral fracture core, respectively. The numerical simulation results are in good agreement with the laboratory experiments. Through the optimized arrangement of the hammer’s impact heads, the problem of longitudinal crack extension of a cracked core can be effectively solved, and the probability of reflection cracks can be reduced.

Multivariate Symmetric Interpolating Dual Multiwavelet Frames

The construction of symmetric multiwavelets in the multivariate case with useful in applications properties is a challenging task, mainly due to the complexity of the matrix extension problem. Nevertheless, for the interpolating case, a general technique can be developed. For an appropriate pair of symmetry group H and matrix dilation M and for a given H-symmetric interpolating refinable matrix mask, a method for the construction of H-symmetric dual refinable matrix masks with a preassigned order of sum rule is suggested. Wavelet matrix masks are constructed using a certain explicit matrix extension algorithm, and their symmetry properties are studied via its polyphase components. The resulting multiwavelet systems form dual multiwavelet frames, where wavelet functions have symmetry properties, preassigned order of vanishing moments and preassigned order of the balancing property. Several examples are presented.

Extension of fuzzy linear operators on fuzzy Riesz spaces

Let E be a fuzzy order vector space, (F,v) be a fuzzy Riesz space with F fuzzy Dedekind complete, K⊂E is a non-empty convex subset, we show that for every fuzzy sublinear θ:K→F, there exists a fuzzy linear operator T:E→F such that T≤θ. This is the generalization of Hahn-Banach theorem in case where the range space is a fuzzy Dedekind complete fuzzy Riesz space. Related extension problems are also studied. Let K be a fuzzy Riesz subspace of E, T:K→F be a fuzzy positive operator, we give a characterization of extreme point of ε(T). We also prove that if K is a fuzzy majorizing vector subspace of E, and T:K→F is a fuzzy positive operator, then the convex set ε(T) has an extreme point.

The strip of analyticity of reflectionless potentials

We study the problem of the analytical extension of bounded reflectionless potentials forthe Schrödinger operator in the Hilbert space $L_2(\mathbb{R})$ and improve an estimate on the strip ofanalyticity established by V. A. Marchenko.

Zero Extension Problem for the Heat Equation

Zero Extension Problem for the Heat Equation

Adherence to self-care recommendations and associated factors among adult heart failure patients in public hospitals, Addis Ababa, Ethiopia, 2021: cross-sectional study

BackgroundAdherence to self-care recommendations in heart failure (HF) patients is essential to improve the patients’ quality of life, prevent hospital admission, and reduce mortality and morbidity. Nevertheless, poor adherence to self-care recommendations remains to be an extensive problem for HF patients. Thus, the aim was to assess adherence to self-care recommendations and associated factors among HF patients in public hospitals, Addis Ababa, Ethiopia, 2021.MethodsAn institutional-based cross-sectional study was conducted among adult HF patients from February 15 to April 15, 2021, in five public hospitals, in Addis Ababa, Ethiopia. A total of 294 adult HF patients completed an interviewer-administered questionnaire in the Amharic language. The Revised HF Compliance Questionnaire was used to measure the adherence to self-care recommendations of HF patients. Data was collected using the Revised HF Compliance Questionnaire, the Japanese heart failure knowledge scale, the multidimensional scale of perceived social support, and the chronic diseases self-efficacy scale. Study participants were selected through a systematic random sampling technique. Data were entered into Epi-info version 7.1 and then exported to SPSS Version 25 for analysis. Descriptive and logistic regression analyses were performed and the statistical significance of associations between the variables was determined using ORs with 95% CI and p-values < 0.05.ResultsAdherence to self-care recommendations among adult HF patients in public hospitals, in Addis Ababa, Ethiopia was 32.70%. Being female (AOR 4.66, 95% CI 1.58–13.67), patients who had high family monthly income (AOR 10.32, 95% CI 2.00–5.13), NYHA class III (AOR: 7.01, 95% CI 2.18–22.57) and class IV (AOR: 6.30, 95% CI 1.01–39.22), who had good self-efficacy (AOR 7.63, 95% CI 2.64–21.97), and who had good knowledge about HF (AOR 3.95, 95% CI 1.56–9.95) were more likely to have good adherence to self-care recommendations, p-value < 0.05.ConclusionThis study revealed that 32.70% of adult HF patients had good adherence to self-care recommendations. Factors associated with adherence to self-care recommendations of adult HF patients are sex, family monthly income, NYHA classification, self-efficacy, and knowledge about HF. Therefore, interventions focused on sex, family monthly income, NYHA classification, self-efficacy, and knowledge about HF are required to improve adherence to self-care recommendations of adult HF patients.

Lifetime Extension of Ultra Low-Altitude Lunar Spacecraft with Low-Thrust Propulsion System

Due to the non-spherical perturbation of the Moon, the lifetime of ultra low-altitude Lunar spacecraft may be quite short. In this paper, we analyze the lifetime of about 50 km-altitude Lunar spacecraft with different initial orbit. The lifetime in low inclination orbits is much shorter than the ones in the near polar orbits. To extend the lifetime and keep the spacecraft in an appropriate range, an orbit maintenance strategy based on low-thrust propulsion system is proposed. The influence of the orbit initial conditions (e.g., semi-major axis, inclination, right ascension of the ascending node) on lifetime extension are discussed and the effect of the low-thrust magnitude in orbit maintenance is analyzed. According to the numerical simulation results, the lifetime of about 50 km-altitude 100 kg Lunar spacecraft with 10 kg fuel and 20 mN thruster can be extended from 7.958 days to over a 109.1725 days, which demonstrates the effectiveness of the strategy. Furthermore, a global perspective for ultra low-altitude Lunar spacecraft lifetime extension problem is provided in this paper, which can be applied to Moon mission designs extensively.

Multi-scale ecological operation model of reservoir group coupled with ecological infiltration irrigation

Aiming at the extensive management problems in ecological operation and ecological irrigation, this paper proposed a novel ecological irrigation method—ecological infiltration irrigation (EII), and established a multi-scale ecological operation model of reservoir group coupled with EII for the irrigation and restoration of river valley grasslands. Firstly, the ecological available water supplies in ecological periods were obtained by long-term ecological operation. Then, reservoirs on mainstream and tributaries gathered flood peaks through real-time ecological operation to create artificial ecological flood processes. Finally, by the joint operation of EII projects, the water level of artificial flood was raised, and the artificial flood was controllably introduced into irrigation districts for the precision irrigation of river valley grasslands. The rationality of ecological operation model and the feasibility of EII technology were then verified through case analysis. Results indicate that: (1) through the 5–9–13 division of ecological irrigation districts, analysis of the ecological water demand, multi-scale ecological operation, EII technology and projects, and other measures, suitable artificial floods can be created and fully introduced into ecological irrigation districts to realize the timely and appropriate irrigation of river valley grasslands; (2) in the critical ecological period in 2018, the core protected area was basically fully irrigated through EII, with an effective irrigation rate of 82.4% and a vegetation coverage of 74.8%, which basically met the ecological water demand of river valley forests and grasses; and (3) for animal husbandry, after using EII technology for grassland irrigation, the average forage yield of river valley grasslands has an increase of 25%, and the direct economic benefit has an average increase of 18.9 million yuan per year, effectively improving the economic income of local herdsmen. The research results have important theoretical and practical significance for the ecological protection and restoration of river valley vegetation.

The extension problem in free harmonic analysis

This paper studies certain aspects of harmonic analysis on nonabelian free groups. We focus on the concept of a positive definite function on the free group and our primary goal is to understand how such functions can be extended from balls of finite radius to the entire group. Previous work showed that such extensions always exist and we study the problem of simultaneous extension of multiple positive definite functions. More specifically, we define a concept of ‘relative energy’ which measures the proximity between a pair of positive definite functions, and show that a pair of positive definite functions on a finite ball can be extended to the entire group without increasing their relative energy. The proof is analytic, involving differentiation of noncommutative Szegö parameters.

The s-polyharmonic extension problem and higher-order fractional Laplacians

We provide a detailed description of the relationships between the fractional Laplacian of order 2s∈(0,n) on Rn and the s-polyharmonic extension operator.

Belief reliability analysis of multi-state deteriorating systems under epistemic uncertainty

Due to the growing complexity of multi-state deteriorating systems and the lack of data, information and knowledge, epistemic uncertainty cannot be ignored anymore. Although there already exist some reliability metrics to deal with epistemic uncertainty problems in multi-state deteriorating systems, the final results provided by these methods are always probability intervals, which will suffer from the interval extension challenge in the subsequent operation. In this paper, we propose a reliability analysis method for the multi-state deteriorating system based on belief reliability theory, which can provide more conservative estimations and avoid interval extension problems. To describe the state transition process of multi-state deteriorating systems under the effect of epistemic uncertainty, a mathematical model called uncertain state transition chain is proposed. Under the framework of uncertainty theory, a total uncertainty inequality is given to assist the calculation of belief reliability. Using the proposed model and inequality, an algorithm of belief reliability for multi-state deteriorating systems considering the uncertainty of inspection time is provided. As a numerical example, the calculating process, the evaluation result and some discussions of a specific deteriorating system are given at last.

Challenges and Constraints Facing the Agricultural Extension System in Egypt

Purpose: The research aimed to identify the important problems facing the agricultural extension system in Egypt. Research Method: A simple random sample was selected from the extension workers in Fayoum and Beheira governorates (196 respondents) Data collection was done from October 2020 to February 2021, using a questionnaire designed based on the framework of modernization and development of agricultural extension systems developed by FAO. Findings: The results indicated that the extension organization in Egypt suffers from aging and erosion (62.2% of the surveyed agricultural extension workers are over 46 years old), 58.7% of the surveyed Extension workers were not specialized in agricultural extension. the extension workers were not sufficiently satisfied with their work. As for the important problems facing extension work in Egypt, foremost of which was the problem centralization, lack of authority delegation, absence of institutional work, absence of funding sources, weakness of the operational budget, weakness of the academic programs before service, absence of adequate training opportunities, absence of a clear and integrative mechanism to link agricultural extension with scientific research institutions, in addition to the absence of coordination with colleges of agriculture and veterinary medicine, mass media, NGOs, and private sector could be identified. Research Limitation: This study was based on a small sample in two governorates. Therefore, policymakers should be careful to generalize the findings to a broad context. Originality/ Value: This study dealt with extension problems within the framework of modernization and development of agricultural extension systems developed by FAO, to provide officials with a vision of the most important problems and reform priorities.

Nested Decomposition Approach for Dispatch Optimization of Large-Scale, Integrated Electricity, Methane and Hydrogen Infrastructures

Energy system integration enables raising operational synergies by coupling the energy infrastructures for electricity, methane, and hydrogen. However, this coupling reinforces the infrastructure interdependencies, increasing the need for integrated modeling of these infrastructures. To analyze the cost-efficient, sustainable, and secure dispatch of applied, large-scale energy infrastructures, an extensive and non-linear optimization problem needs to be solved. This paper introduces a nested decomposition approach with three stages. The method enables an integrated and full-year consideration of large-scale multi-energy systems in hourly resolution, taking into account physical laws of power flows in electricity and gas transmission systems as boundary conditions. For this purpose, a zooming technique successively reduces the temporal scope while first increasing the spatial and last the technical resolution. A use case proves the applicability of the presented approach to large-scale energy systems. To this end, the model is applied to an integrated European energy system model with a detailed focus on Germany in a challenging transport situation. The use case demonstrates the temporal, regional, and cross-sectoral interdependencies in the dispatch of integrated energy infrastructures and thus the benefits of the introduced approach.

Taxonomy enrichment with text and graph vector representations

Knowledge graphs such as DBpedia, Freebase or Wikidata always contain a taxonomic backbone that allows the arrangement and structuring of various concepts in accordance with hypo-hypernym (“class-subclass”) relationship. With the rapid growth of lexical resources for specific domains, the problem of automatic extension of the existing knowledge bases with new words is becoming more and more widespread. In this paper, we address the problem of taxonomy enrichment which aims at adding new words to the existing taxonomy. We present a new method which allows achieving high results on this task with little effort. It uses the resources which exist for the majority of languages, making the method universal. We extend our method by incorporating deep representations of graph structures like node2vec, Poincaré embeddings, GCN etc. that have recently demonstrated promising results on various NLP tasks. Furthermore, combining these representations with word embeddings allows us to beat the state of the art. We conduct a comprehensive study of the existing approaches to taxonomy enrichment based on word and graph vector representations and their fusion approaches. We also explore the ways of using deep learning architectures to extend taxonomic backbones of knowledge graphs. We create a number of datasets for taxonomy extension for English and Russian. We achieve state-of-the-art results across different datasets and provide an in-depth error analysis of mistakes.

Simple algorithms for partial and simultaneous rectangular duals with given contact orientations

A rectangular dual of a graph G is a contact representation of G by axis-aligned rectangles such that (i) no four rectangles share a point and (ii) the union of all rectangles is a rectangle. The partial representation extension problem for rectangular duals asks whether a given partial rectangular dual can be extended to a rectangular dual, that is, whether there exists a rectangular dual where some vertices are represented by prescribed rectangles. The simultaneous representation problem for rectangular duals asks whether two (or more) given graphs that share a subgraph admit rectangular duals that coincide on the shared subgraph. Combinatorially, a rectangular dual can be described by a regular edge labeling (REL), which determines the orientations of the rectangle contacts.We describe linear-time algorithms for the partial representation extension problem and the simultaneous representation problem for rectangular duals when each input graph is given together with a REL. Both algorithms are based on formulations as linear programs, yet they have geometric interpretations and can be seen as extensions of the classic algorithm by Kant and He that computes a rectangular dual for a given graph.