bluuebunny/crossref_metadata_2025 huggingface dataset:
An Optimization-Based Meta-Learning Model for MRI Reconstruction with Diverse Dataset
Authors: Bian Wanyu , Chen Yunmei , Ye Xiaojing , Zhang Qingchao
Published: November 2021

This work aims at developing a generalizable Magnetic Resonance Imaging (MRI) reconstruction method in the meta-learning framework. Specifically, we develop a deep reconstruction network induced by a learnable optimization algorithm (LOA) to solve the nonconvex nonsmooth variational model of MRI image reconstruction. In this model, the nonconvex nonsmooth regularization term is parameterized as a structured deep network where the network parameters can be learned from data. We partition these network parameters into two parts: a task-invariant part for the common feature encoder component of the regularization, and a task-specific part to account for the variations in the heterogeneous training and testing data. We train the regularization parameters in a bilevel optimization framework which significantly improves the robustness of the training process and the generalization ability of the network. We conduct a series of numerical experiments using heterogeneous MRI data sets with various undersampling patterns, ratios, and acquisition settings. The experimental results show that our network yields greatly improved reconstruction quality over existing methods and can generalize well to new reconstruction problems whose undersampling patterns/trajectories are not present during training.
A Hybrid Method for Inland Ship Recognition Using Marine Radar and Closed-Circuit Television
Authors: Liu Xinglong , Li Yicheng , Wu Yong , Wang Zhiyuan , He Wei , Li Zhixiong
Published: November 2021

Vessel recognition plays important role in ensuring navigation safety. However, existing methods are mainly based on a single sensor, such as automatic identification system (AIS), marine radar, closed-circuit television (CCTV), etc. To this end, this paper proposes a coarse-to-fine recognition method by fusing CCTV and marine radar, called multi-scale matching vessel recognition (MSM-VR). This method first proposes a novel calibration method that does not use any additional calibration target. The calibration is transformed to solve an N point registration model. Furthermore, marine radar image is used for coarse detection. A region of interest (ROI) area is computed for coarse detection results. Lastly, we design a novel convolutional neural network (CNN) called VesNet and transform the recognition into feature extraction. The VesNet is used to extract the vessel features. As a result, the MVM-VR method has been validated by using actual datasets collected along different waterways such as Nanjing waterway and Wuhan waterway, China, covering different times and weather conditions. Experimental results show that the MSM-VR method can adapt to different times, different weather conditions, and different waterways with good detection stability. The recognition accuracy is no less than 96%. Compared to other methods, the proposed method has high accuracy and great robustness.
Standardized Dose–Response Curve (sDRC) Construction for OSL Dating of Quartz from Bohai Coast, NE China
Authors: Xia Lei , Li Yan , Chen Yongsheng , Yi Liang , Chen Guangquan , Wang Yancheng , Hu Ke
Published: November 2021

The optically stimulated luminescence (OSL) dating method promises to provide reliable ages for various Quaternary archives. Coastal sedimentation in the Bohai Sea (northeastern China) since the Middle Pleistocene has been influenced by paleoenvironmental and sea-level change, of which dating has been restricted using the OSL dating approach in multiple investigations. In this study, to establish a robust OSL chronological framework of the Bohai coastal sediments more effectively, the regional standardized dose–response curve (sDRC) was constructed for quartz OSL dating in the Bohai Coast (NE China) using two existing approaches. The sDRC-determined equivalent doses are broadly in agreement with those using the individual DRC for each sample. Data used for DRC construction of the fine-grained (FG) quartz samples are less scattered than those of the coarse-grained (CG) quartz samples, probably due to the signal-averaging effect for the FG samples, while the OSL signal of the CG quartz samples might document provenance information that yield relatively scattered distribution. The two approaches used in this study yield identical sDRCs, indicating that both the methods are applicable for sDRC construction in the Bohai Sea.
Joint Tracking of Source and Environment Using Improved Particle Filtering in Shallow Water
Authors: Dai Miao , Li Yaan , Ye Jinying , Yang Kunde
Published: November 2021

Shallow water is a complex sound propagation medium, which is affected by the varying spatial–temporal ocean environment. Taking this complexity into account, the classical processing techniques of source localization and environmental inversion may be improved. In this work, a joint tracking approach for the moving source and environmental parameters of the range-dependent and time-evolving environment in shallow water is presented. The tracking scheme treats both the source parameters (e.g., source depth, range, and speed) and the environmental parameters (e.g., water column sound speed profile (SSP) and sediment parameters) at the source location as unknown variables that evolve as the source moves. To counter sample impoverishment and robustly characterize the evolution of the parameters, an improved particle filter (PF), which is an extension of the standard PF, is proposed. Two examples with simulated data in a slowly changing environment and experimental data collected during the ASIAEX experiment are utilized to demonstrate the effectiveness of the joint approach. The results show that we were able to track the source and environmental parameters simultaneously, and the uncertainties were evaluated in the form of time-evolving posterior probability densities (PPDs). The performance comparison confirms that the improved PF is superior to the standard PF, as it can reduce the parameter uncertainties. The tracking capabilities of the improved PF were verified with high accuracy in real-time source localization and well-estimated rapidly varying parameters. Moreover, the influence of different particle numbers on the improved PF tracking performance is also illustrated.
Integral Sliding Mode Based Finite-Time Tracking Control for Underactuated Surface Vessels with External Disturbances
Authors: Xiao Yunfei , Feng Yuan , Liu Tao , Yu Xiuping , Wang Xianfeng
Published: November 2021

This study focuses on the problem of finite-time tracking control for underactuated surface vessels (USVs) through sliding-mode control algorithms with external disturbances. Considering the nonexistence of relative degree caused by the underactuated property, the initial tracking error system is firstly transformed to a high order system for the possibility of applying a sliding-mode control algorithm. Subsequently, a finite-time controller based on an integral sliding surface (ISMS) is designed to achieve trajectory tracking. With the aid of this controller, the tracking errors converge to a steady state in a finite time. In contrast to the backstepping-based approach, the proposed method makes it possible to integrate controller design of position tracking and attitude tracking in one step, thus ensuring simplicity for implementation. Finally, theoretical analysis and numerical simulations are conducted to confirm the effectiveness of the proposed method.
Approval of an Arrangement in the Restructuring Proceedings and the Financial Condition of Companies Listed on the Stock Exchanges in Warsaw. Is There Any Relationship?
Authors: Prusak Błażej , Galiński Paweł
Published: November 2021

This paper attempts to identify the financial indicators differentiating companies that are insolvent or at risk of insolvency and have successfully entered into an arrangement with their creditors from those that have not. In addition, a two-factor model for predicting the odds of an arrangement has been proposed. The research was conducted using a population of companies listed on stock exchanges in Warsaw that initiated restructuring proceedings between October 2004 and 31 December 2020. Binary logistic regression was used as the research method. The research shows that the financial health of public companies in Poland, as measured by various financial indicators, has little impact on the effectiveness of a debtor–creditor arrangement. The main measure showing discriminatory features between groups of successful and unsuccessful entities is the share of short-term liabilities in total liabilities. A statistically significant influence was also recorded for the indicator showing the share of short-term receivables in the total assets. Furthermore, a statistically significant discriminatory power for both groups was recorded for the indicator showing the ratio of inventories to sales revenue. However, in this situation the selection of this measure was due to the industry diversity of the research population. The identification of these determinants and the proposed model may help courts and supervisors to divide insolvent companies into those that should be subject to liquidation or restructuring procedures at an early stage of the proceedings. Consequently, this can significantly reduce the direct and indirect costs of implementing bankruptcy proceedings.
Beyond Agriculture: Alternative Geographies of Rural Land Investment and Place Effects across the United Kingdom
Authors: Livingstone Nicola , Gallent Nick , Hamiduddin Iqbal , Juntti Meri , Stirling Phoebe
Published: November 2021

Global land ownership patterns have been shifting in recent decades, as institutional and non-traditional investors redirect capital into rural areas. Such investment is a stimulating alternative for innovative profit-driven land uses that move beyond agriculture. This paper explores how ‘new money’ economies have created place effects in three rural case studies across the United Kingdom, through concepts of built, natural, social, and economic capital. The case studies are informed by secondary research, site visits, and interviews, providing snapshots of investment impact. They represent diverse transformations in rural land use via new forms of direct investment, active investment, and processes of financing rather than financialisation, with distinct spatial and temporal characteristics. The case studies include new wine production in Kent, England; transforming the Menie Estate into Trump International Golf Links Scotland (TIGLS); and farm diversification in Northern Ireland. The conclusions tell three investment stories, where place effects reflect the dichotomies, contestation, and symbiosis between investors and local contexts. New land uses create place effects where economic potential often conflicts with natural capital impacts, although they foster knowledge creation and exchange. The underlying values of the investors and their navigation of local politics also have key roles to play in shaping the built, natural, social, and economic place effects.
Exploring Assembly Trajectories of Abandoned Grasslands in Response to 10 Years of Mowing in Sub-Mediterranean Context
Authors: Bricca Alessandro , Tardella Federico Maria , Ferrara Arianna , Panichella Tiziana , Catorci Andrea
Published: November 2021

Abandoned semi-natural grasslands are characterized by lower plant diversity as a consequence of tall grasses spreading. Mowing is a widely used restoration practice, but its effects to maintain the restored diversity over time is poorly investigated in sub-Mediterranean grasslands. Since 2010 in the central Apennines, we fenced a grassland, invaded by Brachypodium rupestre, which was mowed twice a year. Before the experiment started, we recorded species cover in 30 random sampling units (0.5 m × 0.5 m). The sampling was repeated every two years for a total of ten years. We used linear mixed-effect models to investigate the trajectory of functional diversity and community weighted mean for traits related to space occupation, resource exploitation, temporal niche exploitation, and Grime’s CSR strategies. The reduction of the weaker competitor exclusion exerted by B. rupestre affected the functional plant community. In the short term (4–6 years), this fostered space occupation strategies, decreasing convergence of clonal strategies and horizontal space occupation types. In the longer term (8–10 years), mowing filtered ruderal strategies, i.e., species with faster resource acquisition (lower leaf dry matter content, LDMC). LDMC and CSR strategies, initially convergent due to the dominance of B. rupestre, lowered convergence over time due to higher differentiation of strategies.
How Different Are Population Movements between Weekdays and Weekends: A Complex-Network-Based Analysis on 36 Major Chinese Cities
Authors: Zhang Chengyue , Li Minmin , Ma Ding , Guo Renzhong
Published: November 2021

With the rapid development of Information and Communications Technology (ICT) and transportation infrastructure, the flows of people between cities have become the cornerstone of shaping regional integration. Although research studies about the movement of people have aroused widespread interest in academia, research about the temporal and spatial dynamics of daily mobility between cities is sparse, which is called the temporal heterogeneity of mobility between cities. This research aims to study the temporal and spatial changes (Heterogeneity) of population mobility between cities, using big data obtained through China Unicom, in terms of mapping the spatial network of population mobility and complex network analysis, from which the following findings emerge: (1) On weekends, the gap between cities in the number of floating population flow and the capacity of transferring population has become smaller, indicating that there is better coordination between cities on weekends. (2) There are huge differences in population flow between cities, which reflects the imbalance of urban development, population is more concentrated in cities with higher level of development. (3) The heterogeneity of population flow between cities at weekdays and weekends is closely related to the city’s hierarchy, which can help us study the hierarchical structure of China’s cities from a dynamic perspective. The paper emphasizes the importance of researching heterogeneity issues, clarifies the difference between the heterogeneity of weekdays and weekends and the heterogeneity involved in previous population research fields in terms of population flow and deficiencies in research.
Ecological Design Strategies and Theory for Urban Parks in Seoul, 1990s–Present
Authors: Lee Myeong-Jun
Published: November 2021

This study explores the characteristics of and changes in Korean landscape architects’ attitudes toward ecological design strategies and theories over the last three decades. Methodologically, this study includes a literature review and incorporates data from case studies and site visits. It discusses Seoul-specific contexts regarding environmental conditions, urban morphology, administrative agency, and design theory and practice. It redefines ecological parks, expanding their scope using physical and non-physical ecological processes. Considering this redefinition, this study categorizes the five main attitudes of contemporary Korean landscape architects towards ecological design: providing wildlife habitat, constructing aesthetic experiences, the phasing strategy, developing environmental learning programs, and designers’ metaphoric expression. Through these attitudes, this study chronologically explores gradual and constant changes in design strategies and the discourse on ecological design. Specifically, in the 1990s, landscape architects emphasized the representation of ecosystems by constructing wildlife habitats. In the early 2000s, ecological parks were artistically designed as urban parks by reusing post-industrial landscapes. Around the 2010s, landscape architects developed resilient and adaptive design strategies to flexibly respond to uncertain changes in natural and urban ecological circumstances. Since the 2010s, landscape architects have continually expanded the scope of ecology to cover physical, non-physical, urban, and social infrastructures, including public transportation, as well as political, social, and cultural structures and virtual and augmented landscapes. This study can contribute to the field literature while adding a valuable overview of the understudied Korean context.
Urban Innovation Efficiency Improvement in the Guangdong–Hong Kong–Macao Greater Bay Area from the Perspective of Innovation Chains
Authors: Ye Wenzhong , Hu Yaping , Chen Lingming
Published: November 2021

Against the background of globalization and informatization, innovation is the primary driving force for regional economic and social development. Urban agglomerations are the main body of regional participation in global competition, and promoting the construction of the Guangdong–Hong Kong–Macao Greater Bay Area is an important strategy for China’s regional economic development. Aimed at the differences in location advantages among cities in the Guangdong–Hong Kong–Macao Greater Bay Area, based on the theory of innovation chain, we developed a three-stage model of “knowledge innovation-scientific research innovation-product innovation”. A three-stage DEA model was used to measure the innovation efficiency of cities in the Greater Bay Area at different stages, and two progressive two-dimensional matrices are constructed to locate the innovation development of cities according to the efficiency value. The results show the following: ① The overall innovation efficiency of the Greater Bay Area urban agglomerations gradually decreased in the process from knowledge innovation and scientific research innovation to product innovation, and the innovation efficiency among cities was unbalanced. ② Shenzhen, Guangzhou, and Hong Kong all performed well in the whole innovation stage, while other cities in the Greater Bay Area showed weakness in innovation at different stages. Based on this, this paper puts forward relevant countermeasures and suggestions for promoting and optimizing collaborative innovation in the Greater Bay Area taking into account factor flow, industrial structure, and innovation network of urban agglomerations.
Modelling the Event-Based Hydrological Response of Mediterranean Forests to Prescribed Fire and Soil Mulching with Fern Using the Curve Number, Horton and USLE-Family (Universal Soil Loss Equation) Models
Authors: Carra Bruno Gianmarco , Bombino Giuseppe , Lucas-Borja Manuel Esteban , Denisi Pietro , Plaza-Álvarez Pedro Antonio , Zema Demetrio Antonio
Published: November 2021

The SCS-CN, Horton, and USLE-family models are widely used to predict and control runoff and erosion in forest ecosystems. However, in the literature there is no evidence of their use in Mediterranean forests subjected to prescribed fire and soil mulching. To fill this gap, this study evaluates the prediction capability for runoff and soil loss of the SCS-CN, Horton, MUSLE, and USLE-M models in three forests (pine, chestnut, and oak) in Southern Italy. The investigation was carried out at plot and event scales throughout one year, after a prescribed fire and post-fire soil mulching with fern. The SCS-CN and USLE-M models were accurate in predicting runoff volume and soil loss, respectively. In contrast, poor predictions of the modelled hydrological variables were provided by the models in unburned plots, and by the Horton and MUSLE models for all soil conditions. This inaccuracy may have been due to the fact that the runoff and erosion generation mechanisms were saturation-excess and rainsplash, while the Horton and MUSLE models better simulate infiltration-excess and overland flow processes, respectively. For the SCS-CN and USLE-M models, calibration was needed to obtain accurate predictions of surface runoff and soil loss; furthermore, different CNs and C factors must be input throughout the year to simulate the variability of the hydrological response of soil after fire. After calibration, two sets of CNs and C-factor values were suggested for applications of the SCS-CN and USLE-M models, after prescribed fire and fern mulching in Mediterranean forests. Once validated in a wider range of environmental contexts, these models may support land managers in controlling the hydrology of Mediterranean forests that are prone to wildfire risks.
GIS-Based Multi-Criteria Evaluation for Potential Inland Aquaculture Site Selection in the George Town Conurbation, Malaysia
Authors: Bandira Puteri Nur Atiqah , Mahamud Mohd Amirul , Samat Narimah , Tan Mou Leong , Chan Ngai Weng
Published: November 2021

Although the aquaculture industry contributes less than 0.2% to the Gross Domestic Product (GDP) of Malaysia, it has slowly become an important economic activity due to the high-value species productions for domestic and international markets. In addition, aquaculture can potentially be used as a sustainable solution for food security in the future. At present, the selection of aquaculture sites has not received much attention. Thus, this study aims to integrate a Geographic Information System and multi-criteria evaluation approach in identifying the potential sites for brackish aquaculture in the George Town Conurbation, Malaysia. ArcGIS 10.4 was used to perform site selection analysis together with the essential spatial data such as current land use, environmentally sensitive data, and soil quality that influence suitable sites selection for aquaculture. The selection was undertaken in ad hoc manners based on available land identified by aquaculture operators. The results indicated that the George Town Conurbation has a minimal potential site (0.37%) for aquaculture sites. This minimal number results from the expansion of built-up areas towards urban fringe areas; hence less land becomes available for aquaculture. A reasonable buffer zone should be designated as a boundary between urban development and aquaculture to avoid land-use conflict between these two activities.
Development of an End-Toothed Disc-Based Quick-Change Fixture for Ultra-Precision Diamond Cutting
Authors: Zhao Xuesen , Cui Xiangwu , Hu Zhenjiang , Zhang Qiang , Sun Tao
Published: November 2021

With its standardized and unified interface, the quick-change fixture is an important part for maintaining high efficiency without compensation of precision in the metal-turning process because it can conveniently realize high-precision repeated clamping and multi-station conversion without complex positioning and adjustment steps. However, the existing quick-change fixture products and related research cannot fully meet the needs of repeatability and applicability raised from ultra-precision, single-point diamond turning with ultra-high accuracy and ultra-small depth of cut. In this paper, we develop a quick-change fixture for ultra-precision diamond turning, in which the end-toothed disc acts as the positioning element. Specifically, the main parameters of two key components of the end-toothed disc and slotted disc spring are calculated analytically to ensure the positioning accuracy of the designed fixture used in the rotation condition, which is further ensured by controlling the machining tolerance of the tooth profile of the end-toothed disc. Additionally, finite element simulations are performed to investigate the static and modal states of the quick-change fixture, which demonstrate a maximum deformation of about 0.9 μm and a minimum natural frequency of 5655.9 Hz for the designed fixture. Two high-precision sensors are used to detect the radial jump and end run-out values after repeated clamping actions, which are employed to verify the repetitive positioning accuracy of the fixture. Subsequent finite-element simulation of the clamping of small-diameter copper bar, as well as the diamond turning experiment, jointly demonstrate that the designed fixture can achieve a precision of 1 μm. Current work provides an effective quick-change fixture to reduce the deformation of a weak-stiffness workpiece caused by clamping deformation in ultra-precision diamond cutting.
An Inductive Active Filtering Method for Low-Voltage Distribution Networks
Authors: Li Delu , Zhang Xiao , Deng Xianming , Li Changyi
Published: November 2021

Three-phase unbalanced and nonlinear loads aggravate harmonic problems in low-voltage distribution networks. In this paper, a hybrid inductive and active filter (HIAF) system with a Ddy converter transformer is proposed. By establishing the circuit and corresponding mathematical models, the working mechanism of the HIAF system in harmonic suppression is analyzed. In the designed HIAF system, we install the detection point on the grid-side winding and the compensation point on the filtering winding. Since both windings have the same connection, no phase compensation between the harmonic detection point and compensation point is demanded. Eventually, we apply a harmonic damping control and zero-value impedance control strategy to realize harmonic suppression under both balanced and unbalanced loads. The simulation results show that the HIAF system can effectively suppress harmonics under various load conditions.
The Research and Experiments on Contact Sealing Theory of the Underwater Clamp Connector
Authors: Wang Wuchao , Yun Feihong , Sun Haiting , Wang Liquan , Yan Zheping , Wang Gang , Gong Haixia , Jiao Kefeng , Liu Dong , Hao Xiaoquan
Published: November 2021

With regard to the sealing structure characteristics of the underwater clamp connector, based on the Hertz contact theory, this article studies the method of solving the extreme value of the radius of curvature on the two curved surfaces at the sealing contact point; first, the method of calculating the extreme value of the radius of curvature at any surface point of the rotary part is obtained, and then the equivalent radius of curvature is solved. Using finite element simulation to study the contact sealing characteristics without considering the edge thickness and width of the sealing gasket, it is verified that the Hertz contact theory is applicable to the metal contact theory of underwater clamp connectors. Then, the sealing simulation with the influence of the detailed dimensions of the sealing gasket is compared with the theoretical result of the direct application of the Hertz contact theory in the underwater clamp connector contact, and the theoretical correction coefficient of metal contact seal for underwater clamp connectors is introduced to solve the errors. The pressure sealing experiment is carried out on six-inch flange and metal sealing gasket, which proves that the coefficient can greatly enhance the theoretical calculation accuracy of the contact sealing of the underwater clamp connector.
Transformation towards a Smart Maintenance Factory: The Case of a Vessel Maintenance Depot
Authors: Kim Gwang Seok , Lee Young Hoon
Published: November 2021

The conceptualization and framework of smart factories have been intensively studied in previous studies, and the extension to various business areas has been suggested as a future research direction. This paper proposes a method for extending the smart factory concept in the ship building phase to the ship servicing phase through actual examples. In order to expand the study, we identified the differences between manufacturing and maintenance. We proposed a smart transformation procedure, framework, and architecture of a smart maintenance factory. The transformation was a large-scale operation for the entire factory beyond simply applying a single process or specific technology. The transformations were presented through a vessel maintenance depot case and the effects of improvements were discussed.
Computational Study on the Dynamics of a Consumer-Resource Model: The Influence of the Growth Law in the Resource
Authors: Abia Luis M. , Angulo Óscar , López-Marcos Juan Carlos , López-Marcos Miguel Ángel
Published: November 2021

The dynamics of a specific consumer-resource model for Daphnia magna is studied from a numerical point of view. In this study, Malthusian, chemostatic, and Gompertz growth laws for the evolution of the resource population are considered, and the resulting global dynamics of the model are compared as different parameters involved in the model change. In the case of Gompertz growth law, a new complex dynamic is found as the carrying capacity for the resource population increases. The numerical study is carried out with a second-order scheme that approximates the size-dependent density function for individuals in the consumer population. The numerical method is well adapted to the situation in which the growth rate for the consumer individuals is allowed to change the sign and, therefore, individuals in the consumer population can shrink in size as time evolves. The numerical simulations confirm that the shortage of the resource has, as a biological consequence, the effective shrink in size of individuals of the consumer population. Moreover, the choice of the growth law for the resource population can be selected by how the dynamics of the populations match with the qualitative behaviour of the data.
Web-Based Tool for Algebraic Modeling and Mathematical Optimization
Authors: Jusevičius Vaidas , Paulavičius Remigijus
Published: November 2021

In this article, we present a new open-source tool for algebraic modeling and mathematical optimization. We begin by distilling the main gaps within the existing algebraic modeling languages and tools (varying performance, limited cross-compatibility, complex syntax, and different solver, feature, and problem type support). Later, we propose a state-of-the-art web-based tool (WebAML and Optimization System) for algebraic modeling languages and mathematical optimization. The tool does not require specific algebraic language knowledge, allows solving problems using different solvers, and utilizes the best characteristics of existing algebraic modeling languages. We also provide clear extension points and ideas on how we could further improve such a tool.
Hierarchical Cognitive Control for Unknown Dynamic Systems Tracking
Authors: Radac Mircea-Bogdan , Lala Timotei
Published: November 2021

A general control system tracking learning framework is proposed, by which an optimal learned tracking behavior called ‘primitive’ is extrapolated to new unseen trajectories without requiring relearning. This is considered intelligent behavior and strongly related to the neuro-motor cognitive control of biological (human-like) systems that deliver suboptimal executions for tasks outside of their current knowledge base, by using previously memorized experience. However, biological systems do not solve explicit mathematical equations for solving learning and prediction tasks. This stimulates the proposed hierarchical cognitive-like learning framework, based on state-of-the-art model-free control: (1) at the low-level L1, an approximated iterative Value Iteration for linearizing the closed-loop system (CLS) behavior by a linear reference model output tracking is first employed; (2) an experiment-driven Iterative Learning Control (EDILC) applied to the CLS from the reference input to the controlled output learns simple tracking tasks called ‘primitives’ in the secondary L2 level, and (3) the tertiary level L3 extrapolates the primitives’ optimal tracking behavior to new tracking tasks without trial-based relearning. The learning framework relies only on input-output system data to build a virtual state space representation of the underlying controlled system that is assumed to be observable. It has been shown to be effective by experimental validation on a representative, coupled, nonlinear, multivariable real-world system. Able to cope with new unseen scenarios in an optimal fashion, the hierarchical learning framework is an advance toward cognitive control systems.
Solving Schrödinger–Hirota Equation in a Stochastic Environment and Utilizing Generalized Derivatives of the Conformable Type
Authors: Hyder Abd-Allah , Soliman Ahmed H. , Cesarano Clemente , Barakat M. A.
Published: November 2021

This work is devoted to providing new kinds of deterministic and stochastic solutions of one of the famous nonlinear equations that depends on time, called the Schrödinger–Hirota equation. A new and straightforward methodology is offered to extract exact wave solutions of the stochastic nonlinear evolution equations (NEEs) with generalized differential conformable operators (GDCOs). This methodology combines the features of GDCOs, some instruments of white noise analysis, and the generalized Kudryashov scheme. To demonstrate the usefulness and validity of our methodology, we applied it to extract diversified exact wave solutions of the Schrödinger–Hirota equation, particularly in a Wick-type stochastic space and with GDCOs. These wave solutions can be turned into soliton and periodic wave solutions that play a main role in numerous fields of nonlinear physical sciences. Moreover, three-dimensional, contour, and two-dimensional graphical visualizations of some of the extracted solutions are exhibited with some elected functions and parameters. According to the results, our new approach demonstrates the impact of random and conformable factors on the solutions of the Schrödinger–Hirota equation. These findings can be applied to build new models in plasma physics, condensed matter physics, industrial studies, and optical fibers. Furthermore, to reinforce the importance of the acquired solutions, comparative aspects connected to some former works are presented for these types of solutions.
Special Issue “Mathematical Methods for Operations Research Problems”
Authors: Werner Frank
Published: November 2021

This Special Issue of Mathematics is dedicated to the application of Operations Research methods to a wide range of problems [...]
Research of NP-Complete Problems in the Class of Prefractal Graphs
Authors: Kochkarov Rasul
Published: November 2021

NP-complete problems in graphs, such as enumeration and the selection of subgraphs with given characteristics, become especially relevant for large graphs and networks. Herein, particular statements with constraints are proposed to solve such problems, and subclasses of graphs are distinguished. We propose a class of prefractal graphs and review particular statements of NP-complete problems. As an example, algorithms for searching for spanning trees and packing bipartite graphs are proposed. The developed algorithms are polynomial and based on well-known algorithms and are used in the form of procedures. We propose to use the class of prefractal graphs as a tool for studying NP-complete problems and identifying conditions for their solvability. Using prefractal graphs for the modeling of large graphs and networks, it is possible to obtain approximate solutions, and some exact solutions, for problems on natural objects—social networks, transport networks, etc.
Optimal Open-Loop Routing and Threshold-Based Allocation in TWO Parallel QUEUEING Systems with Heterogeneous Servers
Authors: Efrosinin Dmitry , Stepanova Natalia
Published: November 2021

In this paper, we study the problem of optimal routing for the pair of two-server heterogeneous queues operating in parallel and subsequent optimal allocation of customers between the servers in each queue. Heterogeneity implies different servers in terms of speed of service. An open-loop control assumes the static resource allocation when a router has no information about the state of the system. We discuss here the algorithm to calculate the optimal routing policy based on specially constructed Markov-modulated Poisson processes. As an alternative static policy, we consider an optimal Bernoulli splitting which prescribes the optimal allocation probabilities. Then, we show that the optimal allocation policy between the servers within each queue is of threshold type with threshold levels depending on the queue length and phase of an arrival process. This dependence can be neglected by using a heuristic threshold policy. A number of illustrative examples show interesting properties of the systems operating under the introduced policies and their performance characteristics.
A New Quantile Regression Model and Its Diagnostic Analytics for a Weibull Distributed Response with Applications
Authors: Sánchez Luis , Leiva Víctor , Saulo Helton , Marchant Carolina , Sarabia José M.
Published: November 2021

Standard regression models focus on the mean response based on covariates. Quantile regression describes the quantile for a response conditioned to values of covariates. The relevance of quantile regression is even greater when the response follows an asymmetrical distribution. This relevance is because the mean is not a good centrality measure to resume asymmetrically distributed data. In such a scenario, the median is a better measure of the central tendency. Quantile regression, which includes median modeling, is a better alternative to describe asymmetrically distributed data. The Weibull distribution is asymmetrical, has positive support, and has been extensively studied. In this work, we propose a new approach to quantile regression based on the Weibull distribution parameterized by its quantiles. We estimate the model parameters using the maximum likelihood method, discuss their asymptotic properties, and develop hypothesis tests. Two types of residuals are presented to evaluate the model fitting to data. We conduct Monte Carlo simulations to assess the performance of the maximum likelihood estimators and residuals. Local influence techniques are also derived to analyze the impact of perturbations on the estimated parameters, allowing us to detect potentially influential observations. We apply the obtained results to a real-world data set to show how helpful this type of quantile regression model is.
An Efficient Chameleon Swarm Algorithm for Economic Load Dispatch Problem
Authors: Said Mokhtar , El-Rifaie Ali M. , Tolba Mohamed A. , Houssein Essam H. , Deb Sanchari
Published: November 2021

Economic Load Dispatch (ELD) is a complicated and demanding problem for power engineers. ELD relates to the minimization of the economic cost of production, thereby allocating the produced power by each unit in the most possible economic manner. In recent years, emphasis has been laid on minimization of emissions, in addition to cost, resulting in the Combined Economic and Emission Dispatch (CEED) problem. The solutions of the ELD and CEED problems are mostly dominated by metaheuristics. The performance of the Chameleon Swarm Algorithm (CSA) for solving the ELD problem was tested in this work. CSA mimics the hunting and food searching mechanism of chameleons. This algorithm takes into account the dynamics of food hunting of the chameleon on trees, deserts, and near swamps. The performance of the aforementioned algorithm was compared with a number of advanced algorithms in solving the ELD and CEED problems, such as Sine Cosine Algorithm (SCA), Grey Wolf Optimization (GWO), and Earth Worm Algorithm (EWA). The simulated results established the efficacy of the proposed CSA algorithm. The power mismatch factor is the main item in ELD problems. The best value of this factor must tend to nearly zero. The CSA algorithm achieves the best power mismatch values of 3.16×10−13, 4.16×10−12 and 1.28×10−12 for demand loads of 700, 1000, and 1200 MW, respectively, of the ELD problem. The CSA algorithm achieves the best power mismatch values of 6.41×10−13 , 8.92×10−13 and 1.68×10−12 for demand loads of 700, 1000, and 1200 MW, respectively, of the CEED problem. Thus, the CSA algorithm was found to be superior to the algorithms compared in this work.
Robust Multivariate Shewhart Control Chart Based on the Stahel-Donoho Robust Estimator and Mahalanobis Distance for Multivariate Outlier Detection
Authors: Raji Ishaq Adeyanju , Abbas Nasir , Abujiya Mu’azu Ramat , Riaz Muhammad
Published: November 2021

While researchers and practitioners may seamlessly develop methods of detecting outliers in control charts under a univariate setup, detecting and screening outliers in multivariate control charts pose serious challenges. In this study, we propose a robust multivariate control chart based on the Stahel-Donoho robust estimator (SDRE), whilst the process parameters are estimated from phase-I. Through intensive Monte-Carlo simulation, the study presents how the estimation of parameters and presence of outliers affect the efficacy of the Hotelling T2 chart, and then how the proposed outlier detector brings the chart back to normalcy by restoring its efficacy and sensitivity. Run-length properties are used as the performance measures. The run length properties establish the superiority of the proposed scheme over the default multivariate Shewhart control charting scheme. The applicability of the study includes but is not limited to manufacturing and health industries. The study concludes with a real-life application of the proposed chart on a dataset extracted from the manufacturing process of carbon fiber tubes.
Contractive Mappings on Metric Spaces with Graphs
Authors: Reich Simeon , Zaslavski Alexander J.
Published: November 2021

We establish fixed point, stability and genericity theorems for strict contractions on complete metric spaces with graphs.
Accessory Ossicles in the Region of the Foot and Ankle: An Epidemiologic Survey in a Jordanian Population
Authors: Kalbouneh Heba , Alajoulin Omar , Shawaqfeh Jamil , Mustafa Ayman , Jaber Shehab , Zaben Shaima’ , Zapen Ja’far , Alsalem Mohammad
Published: November 2021

Background and Objectives: The incidence of accessory bones in the region of foot and ankle is quite variable between studies and are often confused with avulsion fractures in trauma patients with musculoskeletal injuries. The aim of this study was to assess the incidence of accessory ossicles of the foot and ankle according to gender, side and coexistence, and to determine how frequently accessory ossicles were misdiagnosed as avulsion fractures. Materials and Methods: Oblique and/or lateral foot radiographs of 1000 adult patients referred from emergency departments to foot and ankle clinic were retrospectively reviewed for the presence of accessory ossicles. The Kappa statistic was used in order to assess the validity of radiographic interpretation for the presence of these bones. Results: Accessory ossicles were detected in 40.2% of the radiographs. The incidence rates for the accessory ossicles in order of frequency were: Os trigonum (15.4%), accessory navicular (13.7%), os peroneum (11.5%), os vesalianum (1.1%), os supranaviculare (0.7%), os subfibulare (0.6%), os talotibiale (0.4%), os calcaneus secundarius (0.3%), os supratalare (0.3%), os infranaviculare (0.3%), os intermetatarseum (0.2%), and os subtibiale (0.1%). Coexistence of two or three ossicles in the same foot was observed in 4.4% of the cases, mostly coexistence with os peroneum (2.9%), followed by accessory navicular (1.6%). 2.7% of accessory ossicles were initially misdiagnosed as avulsion fractures at emergency departments. Interrater agreement over identification of different accessory ossicles was found to be reasonably reliable, with a Kappa greater than 0.80 for all assessed bones. Conclusions: In clinical practice, a thorough knowledge of normal anatomical variants is essential to facilitate appropriate diagnosis and treatment and can help to prevent diagnostic errors.
Seroprevalence of the Serological Markers of Transfusion-Transmissible Infections among Volunteer Blood Donors of Kosti Obstetrics and Gynecology Hospital
Authors: Almugadam Babiker Saad , Ibrahim Omer Mohammed Ali , Ahmed Yousif Mousa Alobaid
Published: November 2021

Background: Transfusion-transmissible infections are well-known global health challenges. The present study is proposed to investigate the seropositivity of anti-HIV1/2, anti-HCV, HBsAg, and anti-T.pallidum among volunteer blood donors of Kosti Obstetrics and Gynecology Hospital. Methods: Our study was conducted in a cross-sectional retrospective manner. The data of donors who attended Kosti Obstetrics and Gynecology Hospital throughout 2016 to 2018 were reviewed and retrieved manually from blood bank records. Results: Out of 8139 donors, 22.52% were seropositive for serological markers of TTIs and 1.67% were seropositive for at least two serological markers of TTIs. The overall seropositivity rate of anti-HIV1/2, HBsAg, anti-HCV, and anti-T.pallidum was 1.77%, 6.07%, 1.14%, and 11.87%, respectively (p < 0.000). Anti-T.pallidum was the most frequently detected (p < 0.05) marker across all study variables. TTIs seroprevalence was significantly (p < 0.05) varied according to the age, residence, occupations, and blood groups. Notably, there was a rising trend in the rate of anti-HIV1/2 and seropositivity for more than one marker with age (p < 0.000). Regionally, rural area residents had a higher rate of anti-HIV1/2 (2.20%), HBsAg (6.31%), anti-HCV (1.42%), anti-T.pallidum (18.38%), and multiple markers seropositivity (2.28%) compared to urban areas. Between occupations, the highest rate of anti-HIV1/2 (p = 0.483), HBsAg (p = 0.003), anti-HCV (p = 0.408), anti-T.pallidum (p < 0.000), and multiple markers seropositivity (p < 0.000) were detected in farmers. Regarding the screening, we also found that the frequency of anti-T.pallidum was significantly (p = 0.003) higher in donors who carry the AB+ve blood group, whereas anti-HCV (1.83%) was more frequent in donors carry O−ve blood group (p = 0.255). As seen, anti-T.pallidum+HBsAg was the most frequently (1.22%) co-occurring markers. In contrast, anti-T.pallidum+anti-HIV1/2+HBsAg was the lowest frequency one (p < 0.000). Conclusions: The study showed an alarming rate of TTIs, which suggests the requirement for comprehensive surveillance and health education programs.
Growth and Overall Health of Patients with SLC13A5 Citrate Transporter Disorder
Authors: Brown Tanya L. , Nye Kimberly L. , Porter Brenda E.
Published: November 2021

We were interested in elucidating the non-neurologic health of patients with autosomal recessive SLC13A5 Citrate Transporter (NaCT) Disorder. Multiple variants have been reported that cause a loss of transporter activity, resulting in significant neurologic impairment, including seizures, as well as motor and cognitive dysfunction. Additionally, most patients lack tooth enamel (amelogenesis imperfecta). However, patients have not had their overall health and growth described in detail. Here we characterized the non-neurologic health of 15 patients with medical records uploaded to Ciitizen, a cloud-based patient medical records portal. Ciitizen used a query method for data extraction. Overall, the patients’ records suggested a moderate number of gastrointestinal issues related to feeding, reflux, vomiting and weight gain and a diverse number of respiratory complaints. Other organ systems had single or no abnormal diagnoses, including liver, renal and cardiac. Growth parameters were mostly in the normal range during early life, with a trend toward slower growth in the few adolescent patients with data available. The gastrointestinal and pulmonary issues may at least partially be explained by the severity of the neurologic disorder. More data are needed to clarify if growth is impacted during adolescence and if adult patients develop or are protected from non-neurologic disorders.