Numerous Constraints Research Articles

Window-Based Multi-Objective Optimization for Dynamic Patient Scheduling with Problem-Specific Operators

The problem of patient admission scheduling (PAS) is a nondeterministic polynomial time (NP)-hard combinatorial optimization problem with numerous constraints. Researchers have divided the constraints of this problem into hard (i.e., feasible solution) and soft constraints (i.e., quality solution). The majority of research has dealt with PAS using integer linear programming (ILP) and single objective meta-heuristic searching-based approaches. ILP-based approaches carry high computational demand and the risk of non-feasibility for a large dataset. In a single objective optimization, there is a risk of local minima due to the non-convexity of the problem. In this article, we present the first pareto front-based optimization for PAS using set of meta-heuristic approaches. We selected four multi-objective optimization methods. Problem-specific operators were developed for each of them. Next, we compared them with single objective optimization approaches, namely, simulated annealing and particle swarm optimization. In addition, this article also deals with the dynamical aspect of this problem by comparing historical window-based decomposition with day decomposition, as has previously been proposed in the literature. An evaluation of the models proposed in the article and comparison with traditional models reveals the superiority of our proposed multi-objective optimization with window incorporation in terms of optimality.

Smallholder sheep farmers’ perception of production constraints and competitiveness strategies in South Africa

Sheep production in South Africa has experienced some growth though very slow, and as such production cannot meet demand in the local market. This study aimed to determine the factor influencing the competitiveness of smallholder sheep farmers’ and constraints faced by sheep farmers in South Africa. A farm-level cross-sectional data of 217 smallholder livestock farmers in South Africa were used to identify the factors influencing the competitiveness of smallholder sheep farmers in South Africa. The Porter's Diamond Model Framework was used to measure the competitiveness of sheep production in the study areas and principal component analysis was applied to assess the constraints faced by sheep farmers. The study results found that smallholder sheep farmers in the study area are faced with numerous production constraints, which inhibit their productivity and competitiveness. The most severe constraints include marketing, stock theft, lack of capital, diseases and parasite, and high feed cost. The study suggest that smallholder sheep farmers in the study areas can be competitive and experience growth through the creation of agribusiness enabling environments by promoting policies and strategies that will boost investments in sheep production across the value chain.

An improved seagull optimization algorithm for optimal coordination of distance and directional over-current relays

In this paper, an improved bio-inspired optimization algorithm called Seagull Optimization Algorithm (ISOA) is proposed. ISOA is developed based on three techniques, these techniques use the collaborative optimization strategy, simulating new bird’s generation, and rearranging subgroups. The CEC2020 is utilized to obtain the role and importance of the improved algorithm. Furthermore, the ISOA is applied to find the optimal coordination of Distance and Directional Over-Current Relays (D&DOCRs). The problem of D&DOCRs coordination is more complicated and has numerous constraints. Hence, in this work, a developed object function (DOF) is proposed to set the Distance relays with minimum available settings. ISOA and DOF are tested on the IEEE 8-bus and IEEE 14-bus test systems. ISOA algorithm is used to coordinate the D&DOCRs in both the near and far ends of transmission lines. The results of test systems prove the effectiveness of ISOA to solve the coordination of D&DOCRs using the DOF.

Accounting and the COVID-19 pandemic two years on: insights, gaps, and an agenda for future research.

ABSTRACT The outbreak of the COVID-19 pandemic has imposed numerous constraints, caused enormous disruptions and has been associated with more than 5.8 million deaths worldwide (at the time of writing). It also raised opportunities to imagine a new environment. Accounting academics have been involved in studying and thinking about the questions this poses for research and practice. Accounting scholars have explored the responses to the pandemic crisis and provided important insights about its impact. However, there is relatively little research into how accounting scholarship has contributed collectively to understanding and challenging the effect of the COVID-19 crisis. As accounting scholarship had time to grow, this seems an opportune time to offer a preliminary assessment and an early indication of the emergent themes and challenges. This paper aims to bring together and reconcile insights from an understandably fragmented literature and propose an agenda for future research. The paper provides a conceptual consolidation of published scholarship by establishing connections and identifying key challenges and opportunities. Building on a systematic review of publication patterns across 53 academic journals, the paper analyses the themes explored in the literature as investigated by accounting researchers and identify important gaps. A structured analysis can help identify the role and relevance of accounting scholarship in a way that might not be as clear when examining individual aspects.

A data-driven and application-aware approach to sensory system calibration in an autonomous vehicle

The existing, universal approaches to sensory system calibration do not consider target application during calibration. We propose a new approach to calibration that uses the target application processing pipeline to measure the calibration quality. This approach is exemplified and tested in the calibration of an onboard vision system used to localize a city bus to an electric charging station. Our calibration procedure determines the parameters applying optimization and automatic features detection from a deep learning-based vision processing pipeline. The parameters are calibrated to produce localization estimates matching the ground truth pose measurements. We measure the calibration’s performance in a target application on over 10000 poses recorded from a real city bus over several days. The automatic calibration procedure results in numerous optimization constraints, which can be used to calibrate more parameters and reduce manual labor. The proposed approach reduces the localization errors by almost 50% in the presented target application.

Salt Stress in Plants and Mitigation Approaches.

Salinization of soils and freshwater resources by natural processes and/or human activities has become an increasing issue that affects environmental services and socioeconomic relations. In addition, salinization jeopardizes agroecosystems, inducing salt stress in most cultivated plants (nutrient deficiency, pH and oxidative stress, biomass reduction), and directly affects the quality and quantity of food production. Depending on the type of salt/stress (alkaline or pH-neutral), specific approaches and solutions should be applied to ameliorate the situation on-site. Various agro-hydrotechnical (soil and water conservation, reduced tillage, mulching, rainwater harvesting, irrigation and drainage, control of seawater intrusion), biological (agroforestry, multi-cropping, cultivation of salt-resistant species, bacterial inoculation, promotion of mycorrhiza, grafting with salt-resistant rootstocks), chemical (application of organic and mineral amendments, phytohormones), bio-ecological (breeding, desalination, application of nano-based products, seed biopriming), and/or institutional solutions (salinity monitoring, integrated national and regional strategies) are very effective against salinity/salt stress and numerous other constraints. Advances in computer science (artificial intelligence, machine learning) provide rapid predictions of salinization processes from the field to the global scale, under numerous scenarios, including climate change. Thus, these results represent a comprehensive outcome and tool for a multidisciplinary approach to protect and control salinization, minimizing damages caused by salt stress.

Resolving Constraints in Translating Modifiers in Mungaka Oral Folktales into English

A major challenge encountered when translating Mungaka oral folktales into English centres on the use of modifiers, precisely adjectives and adverbs. The manner in which these grammatical categories are employed in Mungaka oral folktales engenders numerous constraints that render their translation into English difficult. This paper sets out to identify the specific translation constraints that originate from the use of modifiers in Mungaka oral folktales and establish methods to resolve them when translating from Mungaka into English. With the help of unstructured interviews, five Mungaka oral folktales are recorded, transcribed and analyzed qualitatively to identify excerpts that pose translation problems. The use of modifiers in Mungaka gives rise to 16 translation problems (problematic excerpts). The study uses mainly Descriptive Translation Studies (DTS), buttressed by the linguistic, interpretative and aesthetic communication theories of translation, employed to resolve the translation problems in the excerpts. Findings reveal that the translation of Mungaka modifiers is stymied by lexical, semantic and syntactic constraints, and strategies such as transposition, amplification, modulation, omission, substitution, adaptation and reformulation can help in resolving these translation constraints. These strategies are thus recommended for the translation works from Mungaka into English.

SUPER-RESOLUTION IMAGES ON MOBILE SMARTPHONE AIMED AT 3D MODELING

Abstract. In these last years have been calculated several general algorithms to process the images acquired by mobile devices. Nevertheless, they don't always work at their full effectiveness due the numerous constraints and external issues. The latest generation smartphones, pushed by higher user expectations, have increasingly performing camera functions, in particular way, about the always increasing resolution, with a large number of pixels to process or two cameras for stereo view. Considering that pixels in an image sensor synthetizes the number of incoming photons, taking a photograph with a digital camera means to applying a low-pass filter to a scene where the tiny textures, such as characters that measure a few pixels, are observed blurry. This happens when using digital zoom or when the visibility is compromised or during the night artificial lights. For all these reasons the conventional image converter resolution algorithms (as bilinear interpolation algorithm) don’t work with the high-frequency information of a scene once lost. All these aspects are more relevant if we are taking photos to carry out a 3D scenario. Indeed, the 3D model will have an higher geometric accuracy if the image resolution will be higher. Super-Resolution algorithms (SRa) are classified into two categories: (1) approaches that reconstruct a high-resolution image from itself and (2) approaches that register multiple low-resolution images to interpolate sub-pixel information. In this paper we verify the geometric accuracy of a 3D model, when using the Morpho Super-Resolution™ algorithm, also in critical condition. This algorithm doesn’t require pixel shift, indeed, some cameras have a functionality named pixel shift, which captures multiple images while shifting the image sensor.

Efficient computation of time-periodic compressible flows with spectral techniques

A systematic approach to parametrically analyze compressible time-periodic flows is proposed. Instead of time-stepping simulations, a Fourier–Galerkin strategy is adopted, which consists of the projection of the periodic solution onto a truncated Fourier series. Starting from the compressible Navier–Stokes equations, a truncated nonlinear problem coupling the 2N+1 fields, representing the Fourier discretization, is derived. This nonlinear problem is solved by Newton iteration and a set of efficient algorithms for the resolution of the arising inner linear systems is proposed. Compared to alternative methods, the formulation is free of any numerical constraint affecting performance, e.g. a CFL-like condition. It is also free of aliasing effects arising in other spectral techniques. The efficiency of the method is illustrated for two configurations where sound is radiated due to a flow instability, namely the flow around a circular cylinder and the flow through two successive apertures, i.e. the hole-tone configuration.

Study of the Diversity of Nematodes in Vegetable Crops in the Koulikoro Region (Mali)

The market gardening sector is confronted with numerous constraints which weaken and hinder its development. Among these constraints is the importance of plant-parasitic nematodes. For the sustainable management of these worms, a diagnostic evaluation was carried out in two permanent market gardening of Sébéninkoro (Kati) and Koulikoro town in order to determine their diversity. 54 soil samples of 500 g were taken from 3 plots, ie 27 samples per site. Analysis of these samples revealed the presence of 8 genera of nematodes. Among these nematodes, there are nematodes of the genus Meloidogyne very harmful to crops and Tylenchorhynchus. They are common and abundant throughout both sites.

3-D numerical constraints for the Triassic mafic igneous system of Antalya (SW Turkey): Magma generation associated with southern Neotethyan slow seafloor spreading

A ~ 400 m thick Middle-Late Triassic volcano-sedimentary succession crops out in a relatively narrow corridor ~75 km long and ~ 25 km wide close to Antalya Gulf, SW Turkey. The volcanic and subvolcanic rocks represent the majority of the succession and are associated with epiclastic breccia, turbiditic sediments as well as chert and limestone layers. The igneous rocks are alkali basalts, with incompatible element content matching the classical HiMU-OIB types. These are considered as the precursors of a rift system that would have later evolved into a mature Neotethyan oceanic system, with emplacement of massive tholeiitic basalt sequences, not recorded in the investigated area.Clinopyroxene-melt thermobarometric constraints indicate the presence of two main magma chambers, one equilibrated at ~7–10 km depth and ~ 1070 °C and the other at ~15–21 km depth and ~ 1300 °C. Based on these estimates, a 3-D finite element modelling has been applied, simulating the presence of ellipsoidal magma chambers at different depths and with variable sizes, applying different boundary loading conditions. The scenario that best fits the distribution of the volcanic rocks assumes the contemporaneous presence of two magma reservoirs. One is shallow, with a size of ~17 × 1.5 × 1.5 km, and the second is deeper, with a size of ~37 × 3 × 3 km. Numerical simulations show maximum 6 m opening and dilation through horizontal plane at the surface during the Permian/Triassic intracontinental rift phases. Morphological constraints of this rift zone, with the presence of massive lava eruptions also as pillow facies, have been simulated with the existence of a slowly opening rift system. In order to produce the voluminous magma batches in the Antalya region, pure extensional tectonic regimes seem insufficient, and the presence of a transtensional regime must have accompanied the tectonic forces during the Triassic intracontinental rifting stage.

Determining the influencing factors in the residential rooftop solar photovoltaic systems adoption: Evidence from a survey in Qatar

Renewable energy sources have developed rapidly, decreased in cost, and proven to have the potential to limit global warming. Renewable energy in the form of solar energy can be collected through decentralized rooftop solar systems. Solar energy development in Qatar is still at an early stage. The abundance of solar radiation, high GDP, and plentiful access to rooftop spaces make rooftop photovoltaic (PV) systems suitable. Unfortunately, the early development and adoption of residential rooftop solar PV systems are expected to face numerous constraints. This paper investigates the factors that impact the residential rooftop solar photovoltaic adoption in Qatar. Through analyzing the response of a general public sample, we hope to prove the hypothesized factors by aiming at testing their solar systems knowledge and awareness. The result of the study will provide insights on how the public perceives solar panels, along with factors the government needs to address to ensure successful public adoption of residential solar rooftop systems in Qatar.

Multi-Robot Multi-Station Cooperative Spot Welding Task Allocation Based on Stepwise Optimization: An Industrial Case Study

The complicated task allocation, scheduling and planning problem with multiple stations and multiple robots commonly seen in spot welding production line design is studied in this paper. To deal with the highly coupled model combined with several task planning sub-problems, including robot cells design, robots allocation among cells, welding allocation among cells and robots, and welding scheduling for each robot, as well as numerous internal and external constraints, the traditional multi-robot task allocation (MRTA) framework is extended to a novel and uniform multi-station multi-robot (MS-MRTA) framework, and a sophisticated hierarchical optimization algorithm is proposed. Firstly, to establish the optimization model based on MS-MRTA framework as a whole, constraints such as reachability constraint, maximum speed and acceleration constraint, collision constraint and welding operation time constraint are considered, and the optimization objective is established based on the balance of welding tasks of each robot and each cell. Then, in order to solve the highly coupled model, a hierarchical optimization algorithm is proposed to divide the problem into three layers from top to bottom: the path planning of a single robot, welding task allocation among robots, and welding task allocation among cells. The path planning of a single robot is analogous to the Travelling Salesman Problem (TSP) solved by iterating the Lin-Kernighan-Helsgaun (LKH) solver with the trapezoidal acceleration and deceleration motion. To solve the welding task allocation among robots with numerous constraints, a regional assignment method was proposed which simplify the model and eliminate the accessibility constraint and collision constraint, and combined with genetic algorithm to solve the sub-problem iteratively. The welding task allocation among cells is solved based on the principle of balanced welding of each cell. Genetic algorithm is used to obtain the nested iterative solution of three sub-problems. The cases of actual door welding tasks are studied to verify the effectiveness of the proposed optimization algorithm. Compared with the method of long-term trial and error by experienced experts and two other more advanced algorithms, the proposed optimization algorithm results in a task assignment scheme with less welding time, less waiting time and an increase of welding operation productivity, which shows the effectiveness and feasibility of the multi-robot multi-station task allocation algorithm based on stepwise optimization.

Self-interacting dark matter in cosmology: accurate numerical implementation and observational constraints

This paper presents a systematic and accurate treatment of the evolution of cosmological perturbations in self-interacting dark matter models, for particles which decoupled from the primordial plasma while relativistic. We provide a numerical implementation of the Boltzmann hierarchies developed in a previous paper [JCAP, 09 (2020) 041] in a publicly available Boltzmann code and show how it can be applied to realistic DM candidates such as sterile neutrinos either under resonant or non-resonant production mechanisms, and for different field mediators. At difference with traditional fluid approximations — also known as a c eff-c vis parametrizations — our approach follows the evolution of phase-space perturbations under elastic DM interactions for a wide range of interaction models, including the effects of late kinetic decoupling. Finally, we analyze the imprints left by different self interacting models on linear structure formation, which can be constrained using Lyman-α forest and satellite counts. We find new lower bounds on the particle mass that are less restrictive than previous constraints.

Assessment and Evaluation of IWRM Implementation in Palawan, Philippines

According to the United Nation's Sustainable Development Goal (SDG 6), the world needs to sustainably manage water resources through integrated water resource management (IWRM). The Philippines is committed to this goal by ensuring the implementation of IWRM at all levels. Concurrently, there is growing evidence that there is presently no consolidated data on the status of implementation at the sub-national level. With water shortages on the increase, it's more important than ever to find solutions to settle disputes and trade-offs so that water can be distributed effectively, sustainably, and equally. This paper aims to investigate the degree of implementation of IWRM that presents the actual state of affairs in terms of water management at the sub-national level. This study is focused on Palawan Province, with the following sites: Puerto Princesa City, El Nido, Roxas, and Taytay. A structured survey questionnaire was drawn up in accordance with the existing questionnaire developed for this purpose. The obtained data were computed using the steps developed for calculating the indicators of IWRM implementation degree. Puerto Princesa City, El Nido, Roxas, and Taytay have the following IWRM ratings: 39.93, 32.03, 37.99, and 36.32%, respectively, which means "medium-low" in which the IWRM components have largely been institutionalized, and deployment is well underway. In these regions, a subnational water management scheme exists, but its maximum capacity is mostly unrealized due to numerous constraints. The findings show that the numerous water laws are confusing and that water data for planning purposes is lacking. Even though there are many water agencies, they are not interconnected. This study is useful for successful IWRM implementation, which should encourage sustainable water resource management for environmental sustainability. Integrated methods for water resource management help to organize sustainable growth by assessing how water is handled in agriculture, urban applications, and the surrounding ecosystems. Doi: 10.28991/CEJ-2022-08-02-08 Full Text: PDF

Evolutionary Landscapes of Host-Virus Arms Races.

Vertebrate immune systems suppress viral infection using both innate restriction factors and adaptive immunity. Viruses mutate to escape these defenses, driving hosts to counterevolve to regain fitness. This cycle recurs repeatedly, resulting in an evolutionary arms race whose outcome depends on the pace and likelihood of adaptation by host and viral genes. Although viruses evolve faster than their vertebrate hosts, their proteins are subject to numerous functional constraints that impact the probability of adaptation. These constraints are globally defined by evolutionary landscapes, which describe the fitness and adaptive potential of all possible mutations. We review deep mutational scanning experiments mapping the evolutionary landscapes of both host and viral proteins engaged in arms races. For restriction factors and some broadly neutralizing antibodies, landscapes favor the host, which may help to level the evolutionary playing field against rapidly evolving viruses. We discuss the biophysical underpinnings of these landscapes and their therapeutic implications.

Polynomial relations between operators on chains of representation rings

Given a chain of groups we may form the corresponding chain of their representation rings, together with induction and restriction operators. Let denote the operator which restricts down l steps, and similarly for Observe that is an operator from any particular representation ring to itself. We provide explicit rigid constraints that a group of chain with surjective restriction operators satisfying the polynomial property must obey. The central question that this paper addresses is: “What happens if the operator is a polynomial in the operator?” It is well known that chains of wreath products have this property. In this paper, we deduce rigid numerical constraints any arbitrary chains of groups with surjective restriction operator and the aforementioned polynomial property must satisfy. These polynomials can be obtained from the orders of the groups, and are uniquely parametrized by two integers. We deduce the desired parametrization from deducing character theoretic properties of group chains with the desired polynomials.

2 - Quality Issues in Kenya’s Higher Education Institutions

The capability of higher education institutions (HEIs) to serve as drivers of economic competitiveness is reducing in different developing countries due to numerous constraints which interfere with their quality. This article empirically investigated the quality assurance practices in Kenya’s HEIs, efficacy of the frameworks used, gaps and opportunities for improvement. Perceptions on eight dimensions of quality, namely, governance and management, programme planning and management, curriculum development, teaching and learning, infrastructure, assessment, research, publication and innovation and programme results were sought from three categories of respondents in eight universities.Data were collected from a sample of 136 academic staff, 340 students, and 34 staff of quality assurance directorates out of a total of 222,384, and 38 targeted respondents respectively. A 7 point Likert scale: questionnaire (ranging from 1= Strongly Disagree to 7 = Strongly Agree) was administered. The quantitative data was corroborated through interviewing the three respondent groups in the study. Analysis of gaps depicted by the differences in the weighted averages of responses of staff of quality assurance directorates and academic staff, staff of quality assurance directorates and students, and academic staff and students was done. Each HEI was first analysed individually and then findings were consolidated to obtain the overall gap on each quality dimension studied across all participating HEIs. Results indicated revealed gaps in each of the eight dimensions of quality investigated and showed Kenya’s HEIs were at different levels on the quality continuum. Hence as the results are suggestive of room for improvement, HEIs have the opportunity to benchmark with local HEIs that have progressed on certain parameters of quality and, evolve homegrown models of best practice. This will enable these institutions to continuously improve their positioning on the quality continuum which is a key tenet of quality management. The most challenged dimension was research and publication. The research recommends that Commission for University Education (CUE) should strengthen accountability mechanisms in the HEIs. It brings to the fore the need for HEIs to develop and strengthen their collaborations and networks between themselves and with industry.

Construction of wave dark matter halos: Numerical algorithm and analytical constraints

We present a wave generalization of the classic Schwarzschild method for constructing self-consistent halos -- such a halo consists of a suitable superposition of waves instead of particle orbits, chosen to yield a desired mean density profile. As an illustration, the method is applied to spherically symmetric halos. We derive an analytic relation between the particle distribution function and the wave superposition amplitudes, and show how it simplifies in the high energy (WKB) limit. We verify the stability of such constructed halos by numerically evolving the Schr\"odinger-Poisson system. The algorithm provides an efficient and accurate way to simulate the time-dependent halo substructures from wave interference. We use this method to construct halos with a variety of density profiles, all of which have a core from the ground-state wave function, though the core-halo relation need not be the standard one.

Numerical integration algorithms and constraint formulations for an ALE-ANCF cable element

In this study, the Absolute Nodal Coordinate Formulation (ANCF) is examined in the framework of the Arbitrary Lagrangian–Eulerian (ALE) formulation for cable simulation. The objective is to determine the stability, efficiency, and accuracy in different frequency domains for two different numerical time integration methods. The methods being compared are the Runge–Kutta method RK4, and the Generalized-α method. For simulations where the lower frequency domain is of interest, the Generalized-α method is stable, accurate and can be used with large time-steps; while where the high frequency domains is of interest, the RK4 procedure can be a more efficient method.The penalty method, the Lagrange multiplier method and linear coupling are tested as constraint methods for connecting ALE-ANCF cable elements. For RK4, the penalty constraint method highly affects the maximum time-step, which again affects the total solution time. For the Generalized-α method, the constraint methods all provide accurate results, and they have similar solution time. ALE-ANCF cable elements can be connected by different constraint techniques without impeding the ability to exhibit large deformations.