Space Form Research Articles

First Chen Inequality for General Warped Product Submanifolds of a Riemannian Space Form and Applications

First Chen Inequality for General Warped Product Submanifolds of a Riemannian Space Form and Applications

Analysis of longitudinal dynamic stability of tandem wing aircraft

PurposeTandem wing aircrafts belong to an unconventional configurations group, and this type of design is characterised by a strong aerodynamic coupling, which results in lower induced drag. The purpose of this paper is to determine whether a certain trend in the wingspan impact on aircraft dynamic stability can be identified. The secondary goal was to compare the response to control of flaps placed on a front and rear wing.Design/methodology/approachThe aerodynamic data and control derivatives were obtained from the computational fluid dynamics computations performed by the MGAERO software. The equations of aircraft longitudinal motion in a state space form were used. The equations were built based on the aerodynamic coefficients, stability and control derivatives. The analysis of the dynamic stability was done in the MATLAB by solving the eigenvalue problem. The response to control was computed by the step response method using MATLAB.FindingsThe results of this study showed that because of a strong aerodynamic coupling, a nonlinear relation between the wing size and aircraft dynamic stability proprieties was observed. In the case of the flap deflection, stronger oscillation was observed for the front flap.Originality/valueResults of dynamic stability of aircraft in the tandem wing configuration can be found in the literature, but those studies show outcomes of a single configuration, while this paper presents a comprehensive investigation into the impact of wingspan on aircraft dynamic stability. The results reveal that because of a strong aerodynamic coupling, the relation between the span factor and dynamic stability is nonlinear. Also, it has been demonstrated that the configuration of two wings with the same span is not the optimal one from the aerodynamic point of view.

Innovative development of the education industry in the European higher education area

The article identifies positive changes and suggests trends in the innovative development of the educational sector in the European area of higher education. The goal is determined, and the functions of the European area of higher education are considered. It has been proven that two trends, which are analyzed in the article, prevail in the structure of world higher education: unitary (single), a system manifested in higher education and provided by universities; binary (dual), a system with a traditional education sector based on the Humboldt University concept and a separate non-university sector of higher education. The main principles regulating aspects of educational activity are revealed. Considered is a very important and necessary distance form in the educational space, related to the introduction of information and communication technologies into the educational process, which is being updated and developed to improve an open and widely accessible education system, aimed at training a qualified competitive specialist.

PREVENTION OF SUICIDAL ACTIVITY USING VIRTUAL REALITY INTERVENTIONS

Advancements in technology within the reality–virtuality (RV) continuum offer novel avenues for addressing mental health and psychosocial support, supplementing traditional approaches. Consequently, it is imperative to investigate how these immersive interactions affect potential beneficiaries. Goal. This article is devoted to the analysis of immersive technologies potential, specifically virtual reality (VR), in the context of suicide prevention. Methods. The authors investigate the psychological effects of using VR technologies as a preventive intervention for suicidal behavior. It is organized within the framework of an experimental procedure designed according to Solomon's plan, in which the independent variable (IN) was watching a 360° video in VR glasses, and the dependent variables (DVs) were factors associated with suicidality, namely: emotional affect (positive and negative), hopelessness, and indicators of individual well-being levels. The Questionnaire on Positive and Negative Affects (OPANA), Beck's Hopelessness Scale, and the "Modified BBC Subjective Well-Being Scale (BBC-SWB)" were used to measure these indicators. The experimental hypothesis of our study: watching a 360° video in virtual reality glasses has an effect on parameters associated with suicidality. Results. In this article, we highlight the results of the comparison of the control and experimental groups regarding the impact on the measured psychological effects by analyzing the indicators before and after the use of the intervention through the mediation of immersive technologies. The findings demonstrate statistically significant enhancements in positive affect, psychological, physical, and subjective well-being within the experimental group compared to the control group. Trends toward improvement were also observed in measures of negative affect and relationship well-being, although they did not reach statistically significant levels. The hopelessness score improved in both groups, which may indicate a general ameliorative effect on the participants in such an experimental procedure. Conclusions. Our study reveals that a one-time intervention mediated by immersive technologies, namely viewing a 360° video in VR glasses, contributed to the improvement of measurable psychological effects of indicators associated with suicidality and can potentially be used as a means of preventing suicidal behavior. The experimental hypothesis of our study was confirmed. In the future, a comprehensive study of the obtained results regarding the effect of preliminary testing and expansion of meaningful interpretation of the data is necessary; as well as related studies of the long-term effect, series of interventions, specifics of the context of the video presented in the virtual space and alternative forms of prevention and impact on measurable indicators.

Sensory gardens as a new form of urban green space in smart sustainable cities

Sensory gardens have been known since antiquity, but they are becoming more and more important in terms of smart city development. The article presents a literature review on the diverse functions of sensory gardens, the concept of a smart and green city, and the sensory garden as a new form of urban green spaces (UGS). The aim of the research was to identify expectations regarding the development of modern gardens in urban spaces, in the context of a smart city. The primary data collection method was social surveys on the expectations regarding the development of parks and city gardens, carried out among the inhabitants of Poland and Russia. The studied sample had a total of 230 people. The research was conducted in January 2021 using an internet survey. The questions were both open and closed, and related to issues such as: (1) the most important features of gardens and city parks; (2) the definition of a sensory garden; (3) the main functions that gardens and city parks should fulfil in the future. The results of the conducted research confirmed the adopted hypothesis that sensory gardens as green enclaves with different functions constitute new, prospective forms of development of urban green spaces in smart sustainable cities. The social needs for urban green spaces are clear and reflect current environmental problems regarding the quality of atmospheric air and access to green spaces in the vicinity. The respondents agree that the most important features of gardens and parks include fresh air and the possibility of resting. Keywords: green city, sustainable city, smart city, urban areas, sensory gardens; smart green city, smart green integration, and smart gardens.

Estimation of Ricci Curvature for Hemi-Slant Warped Product Submanifolds of Generalized Complex Space Forms and Their Applications

In this paper, we estimate Ricci curvature inequalities for a hemi-slant warped product submanifold immersed isometrically in a generalized complex space form with a nearly Kaehler structure, and the equality cases are also discussed. Moreover, we also gave the equivalent version of these inequalities. In a later study, we will exhibit the application of differential equations to the acquired results. In fact, we prove that the base manifold is isometric to Euclidean space under a specific condition.

전북 임실군 삼계면 어은마을의 건축-공간적 특성 고찰

This study investigated and analyzed the village space and architectural characteristics of Eoeun Village, Samgye-myeon, Imsil-gun, Jeonbuk. The space of the village was formed based on the idea of feng shui, and the Confucian hierarchical idea determined the location, size, and structure of the building. Recently, clan villages in rural areas have been dismantled and damaged due to population outflow and urbanization. In this situation, Eoeun Village, which preserves the traditional space and residential form at the time of the village's creation, is considered to be worth preserving and studying.

Grid-Following Inverter-Based Resource: Numerical State–Space Modeling

In the pursuit of a sustainable electric power system, the integration of renewable energy sources and distributed energy resources is gradually replacing traditional power generation. These new resources are integrated into the grid via inverters, which, despite their efficient performance, present dynamic challenges to the power grid when implemented on a large scale. To maintain grid stability and ensure effective regulation during abnormal operations, various modeling techniques are necessary; while the dynamics of inverter-based resources (IBRs) are traditionally modeled by transfer functions, this paper sheds light on differential-algebraic equations (DAEs) modeling and numerical integration methods. The inherent limitations of transfer function modeling stem from its restricted applicability, as it is exclusively suitable for linear and time-invariant systems. In contrast, the nonlinear DAEs of the IBR system can be converted into a state–space form, which offers a versatile framework for modeling, evaluating, and designing a diverse array of systems. In addition to being compatible with time-varying systems and multiple-input multiple-output systems, the state–space technique may incorporate saturation and dead zone characteristics into the dynamic model. Our research focuses on IBR modeling in a grid-following scheme, which is current-controlled and synchronized to the grid by a phase-locked loop (PLL). The presented state–space model consists of the inverter, grid, control, and designed PLL. Beyond the discussion of its application to IBRs, the presented method holds the potential to solve a wide range of DAEs. The proposed model is compared with a benchmarked system.

BinderSpace: A package for sequence space analyses for datasets of affinity-selected oligonucleotides and peptide-based molecules.

Discovery of target-binding molecules, such as aptamers and peptides, is usually performed with the use of high-throughput experimental screening methods. These methods typically generate large datasets of sequences of target-binding molecules, which can be enriched with high affinity binders. However, the identification of the highest affinity binders from these large datasets often requires additional low-throughput experiments or other approaches. Bioinformatics-based analyses could be helpful to better understand these large datasets and identify the parts of the sequence space enriched with high affinity binders. BinderSpace is an open-source Python package that performs motif analysis, sequence space visualization, clustering analyses, and sequence extraction from clusters of interest. The motif analysis, resulting in text-based and visual output of motifs, can also provide heat maps of previously measured user-defined functional properties for all the motif-containing molecules. Users can also run principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) analyses on whole datasets and on motif-related subsets of the data. Functionally important sequences can also be highlighted in the resulting PCA and t-SNE maps. If points (sequences) in two-dimensional maps in PCA or t-SNE space form clusters, users can perform clustering analyses on their data, and extract sequences from clusters of interest. We demonstrate the use of BinderSpace on a dataset of oligonucleotides binding to single-wall carbon nanotubes in the presence and absence of a bioanalyte, and on a dataset of cyclic peptidomimetics binding to bovine carbonic anhydrase protein. BinderSpace is openly accessible to the public via the GitHub website: https://github.com/vukoviclab/BinderSpace.

Multi‐scale coordinated optimal dispatch method of electricity‐thermal‐hydrogen integrated energy systems

AbstractTo achieve carbon neutrality, renewable energy‐based power systems and hydrogen are increasingly being promoted. A novel electricity‐thermal‐hydrogen integrated energy system that combines new energy generation, multi‐source load, and multiple energy storage is proposed by the authors. To address uncertainties in new energy output, and issues of untimely unit regulation response and large planning tracking errors, a multi‐scale scheduling method based on model predictive control (MPC) was proposed. In the day‐ahead dispatching stage, an optimal economic dispatching model was established with the lowest system operation cost as the optimisation objective. The model considers equipment investment, operation, maintenance, and peak‐to‐valley differences in electricity prices. In the intraday dispatching stage, an MPC‐based intraday rolling optimisation correction strategy was proposed to cope with contact line power fluctuations caused by prediction errors of new energy and multi‐source load. This strategy combines time‐domain rolling and feedback correction of the real‐time system state to eliminate the influence of uncertainty factors in the microgrid. The MPC‐based intraday rolling optimal scheduling model was established in the form of a discrete state space and transformed into a quadratic planning problem to improve the efficiency and accuracy of the model solution. Finally, a typical microgrid was used as an example to verify the effectiveness of the proposed method. Results show that the contact line tracking error can be within 0.025 kW, and the single scheduling time was within 0.14 s.

Triharmonic hypersurfaces with constant mean curvature in pseudo-Riemannian space forms

In this paper, triharmonic hypersurfaces with constant mean curvature in pseudo-Riemannian space forms are studied. Under the assumption that the shape operator is diagonalizable, we first classify completely the nonminimal hypersurfaces with at most two distinct principal curvatures and give some examples of non-biharmonic triharmonic hypersurfaces. Then, we prove that the hypersurfaces with at most four distinct principal curvatures have constant scalar curvature. As a consequence, we obtain that such triharmonic hypersurfaces in pseudo-Euclidean spaces are minimal, which gives an affirmative partial solution to the generalized Chen's conjecture in [21].

Dependent state space Student‐t processes for imputation and data augmentation in plasma diagnostics

AbstractMultivariate time series measurements in plasma diagnostics present several challenges when training machine learning models: the availability of only a few labeled data increases the risk of overfitting, and missing data points or outliers due to sensor failures pose additional difficulties. To overcome these issues, we introduce a fast and robust regression model that enables imputation of missing points and data augmentation by massive sampling while exploiting the inherent correlation between input signals. The underlying Student‐t process allows for a noise distribution with heavy tails and thus produces robust results in the case of outliers. We consider the state space form of the Student‐t process, which reduces the computational complexity and makes the model suitable for high‐resolution time series. We evaluate the performance of the proposed method using two test cases, one of which was inspired by measurements of flux loop signals.

Using social capital to address youth sexual and reproductive health and rights in disaster preparedness and response: A qualitative study highlighting the strengths of Pacific community organisations and networks.

In the Pacific region, youth sexual and reproductive health and rights (SRHR) are strongly influenced by sociocultural and structural factors, which limit access to SRHR information and services for youth. As climate-related disasters intensify in the Pacific, existing challenges to youth SRHR may increase the risk of worse SRHR experiences and outcomes for youth before, during and after disasters. Community-based models of SRHR service provision models increase accessibility for youth in non-disaster times, but there is limited evidence of how community organisations address youth SRHR in disaster contexts. We conducted qualitative interviews with 16 participants from community organisations and networks in Fiji, Vanuatu, and Tonga following the 2020 Tropical Cyclone (TC) Harold. Guided by the Recovery Capitals Framework (natural, built, political, cultural, human, social, and financial capitals), we explored how community organisations addressed challenges to facilitate access to youth SRHR information and services. Social capital in the form of peer networks and virtual safe spaces was used to navigate challenges in political, financial, and natural capitals. Existing relationships and trusted collaborations were crucial to address cultural taboos related to youth SRHR. Previous experiences of disasters and knowledge of contexts enabled participants to provide sustainable solutions to identified SRHR needs. The work conducted by community organisations and networks pre-disaster made it easier to identify and address youth SRHR risks following disasters. Our research offers a unique perspective into how social capitals were used to mitigate challenges to youth SRHR across natural, human, financial, cultural, built, and political capitals. Findings offer important opportunities to invest in existing community strengths, for transformative action to advance the SRHR of Pacific youth.

Least-squares neural network (LSNN) method for scalar nonlinear hyperbolic conservation laws: Discrete divergence operator

A least-squares neural network (LSNN) method was introduced for solving scalar linear and nonlinear hyperbolic conservation laws (HCLs) in Cai et al. (2021, 2022). This method is based on an equivalent least-squares (LS) formulation and uses ReLU neural network as approximating functions, making it ideal for approximating discontinuous functions with unknown interface location. In the design of the LSNN method for HCLs, the numerical approximation of differential operators is a critical factor, and standard numerical or automatic differentiation along coordinate directions can often lead to a failed NN-based method. To overcome this challenge, this paper rewrites HCLs in their divergence form of space and time and introduces a new discrete divergence operator. As a result, the proposed LSNN method is free of penalization of artificial viscosity.Theoretically, the accuracy of the discrete divergence operator is estimated even for discontinuous solutions. Numerically, the LSNN method with the new discrete divergence operator was tested for several benchmark problems with both convex and non-convex fluxes, and was able to compute the correct physical solution for problems with rarefaction, shock or compound waves. The method is capable of capturing the shock of the underlying problem without oscillation or smearing, even without any penalization of the entropy condition, total variation, and/or artificial viscosity.

Understanding the Influence of Urban Form on the Physical Activity in the Open Spaces Using Photovoice Method

This study presents the photovoice approach, a participatory qualitative research tool to study the relationship between urban form and physical activity in urban open spaces. According to the World Health Organization, increased automation of daily tasks and work has decreased physical activity over recent years across all age groups. One of the significant factors that determines an active lifestyle is the way our cities are built and the urban environment is designed. This study investigates perceived beneficial or negative impact of built environment on the levels of physical activity that result for both individuals and communities.

Minimal Legendrian submanifolds in Sasakian space forms with C-parallel second fundamental form

It is known that Cheng-He-Hu [3] gave a complete classification of the n-dimensional C-totally real (or equivalently, Legendrian) minimal submanifolds in the (2n+1)-dimensional Sasakian space form N2n+1(c) with constant sectional curvature. According to this classification and the proof therein, such minimal Legendrian submanifolds are all of C-parallel second fundamental form. The purpose of this paper is to extend the above result partly, and as the main results, we classify all the minimal Legendrian submanifolds in N2n+1(c) with C-parallel second fundamental form in cases n=2,3,4.

Inequalities on Isotropic Submanifolds in Pseudo-Riemannian Space Forms

Spacelike and timelike isotropic submanifolds of pseudo-Riemannian spaces have interesting properties, with important applications in Mathematics and Physics. The article presents inequalities for isotropic spacelike and timelike submanifolds of pseudo-Riemannian space forms and isotropic Lorentzian submanifolds are also considered.

Ricci Soliton of CR-Warped Product Manifolds and Their Classifications

In this article, we derived an equality for CR-warped product in a complex space form which forms the relationship between the gradient and Laplacian of the warping function and second fundamental form. We derived the necessary conditions of a CR-warped product submanifolds in Ka¨hler manifold to be an Einstein manifold in the impact of gradient Ricci soliton. Some classification of CR-warped product submanifolds in the Ka¨hler manifold by using the Euler–Lagrange equation, Dirichlet energy and Hamiltonian is given. We also derive some characterizations of Einstein warped product manifolds under the impact of Ricci Curvature and Divergence of Hessian tensor.

Epidemiology of postoperative spinal wound infection in the Middle East and North Africa (MENA) region

BackgroundDespite the extensive literature on postoperative spinal wound infection, yet to our knowledge, there is no previous study containing combined data from several sites in the Middle East and North Africa (MENA) region. This study aimed to estimate the incidence of surgical site infection (SSI) following spine surgeries, its associated factors, and management. MethodsIn a retrospective cohort study, medical records of all patients ≥18 years of age who underwent spine surgery at 6 tertiary referral centers in the MENA region between January 2014 to December 2019 (n=5,872) were examined to collect data on the following: (1) Patient's characteristics, (2) Disease characteristics, (3) Spine surgery approach, and (4) Characteristics of Postoperative SSI. The determinants of postoperative SSI were identified using logistic regression analysis. Receiver operating characteristic (ROC) curve was applied to identify the cut-off of the length of stay in the hospital postoperatively till the infection is likely to occur. Significance was set at p<.05. ResultsThe overall incidence of SSI was 4.2% (95% CI: 3.72–4.77), in the form of deep (46.4%), superficial (43.1%), dehiscence (9.3%), and organ space (1.2%) infections. After adjusting for all possible confounders, significant predictors of postoperative SSI were; diabetes (OR=2.12, p<.001), smoking (OR=1.66, p=.002), revision surgery (OR=2.20, p<.001), open surgery (OR=2.73, p<.001), perioperative blood transfusion (OR=1.45, p=.033), ASA class III(OR=2.08, p=.002), and ≥4 days length of stay "LOS" (OR= 1.71, p=.001). A cut-off of 4 days was the optimum LOS above which postoperative SSI is more likely to occur, with 0.70 sensitivity, 0.47 specificity, and 0.61 area under the curve. ConclusionsThis is the first study that highlighted the incidence of postoperative SSI in spine surgery in the MENA region. Incidence figures are comparable to figures in different areas of the world. Identifying predictors of SSI might help high‑risk patients benefit from more intensive wound management.

Anatomical Pathology Differences in Lung Alveoli Damage with Exposure to Conventional and Electric Cigarettes

In conventional cigarettes, tobacco is a major risk factor in the development of diseases involving the lungs, including pulmonary emphysema, fibrosis and lung cancer. Many people think that using e-cigarettes is much safer than conventional cigarettes. Whereas smoking with electronic cigarettes can cause the same feeling of cotton mouth as felt by conventional smokers, with symptoms such as itchy throat, cough and complications to the lungs. This literature review conducted a literature search with the keywords cigarette, e-cigarette, popcorn lung, and alveoli. Conventional cigarettes and electronic cigarettes (e-cigarettes) cause damage to the pulmonary alveoli in the form of alveolar spaces; this depends on the nicotine content in them. Electronic cigarettes and conventional cigarettes exert different effects on the oxidative stress response of the airway epithelium. In addition, the image of popcorn lung can be found due to the presence of diacetyl that appears when heating e-juices in e-cigarettes.