Space Method Research Articles

Non-probabilistic reliability analysis with both multi-super-ellipsoidal input and fuzzy state

In real-world engineering scenarios, incomplete uncertainty information and ambiguous failure states persist and pose significant challenges for structural reliability analysis. This paper introduces a non-probabilistic fuzzy reliability analysis (NPFRA) model featuring fuzzy output states, where the input uncertainties are quantified by a multi-super-ellipsoidal model. Initially, we define both reliability and failure indices of NPFRA, and provide the corresponding Monte Carlo simulation (MCS) solution. Additionally, an extended variable space (EVS) method is established to transform the NPFRA problem into a conventional non-probabilistic reliability analysis (NPRA) one, and MCS based on EVS is derived accordingly. To address the efficiency issue of MCS, a novel method called active learning kriging with norm-constrained expected risk function (ALK-NERF) is developed explicitly for NPFRA. Four examples are adopted to verify the rationality and effectiveness of the proposed ALK-NERF for NPFRA.

Numerical simulation of Darcy–Brinkman oscillatory flow of dissipative fluid: Utilization of finite difference method

This study investigates viscous flow behavior in a Darcy–Brinkman porous medium, considering the effects of porous dissipation and frictional heating. The fluid is flowing over a flat plate, oscillating in its plane. The velocity and temperature profiles are simulated using a mathematical model that includes linear convection and considers the effects of porous and viscous dissipation. After performing mathematical transformations, the governing equations are modified into coupled and nonlinear dimensionless PDEs. The forward time centered space method numerically solves the modeled dimensionless equations. The acquired results are explicitly validated against the findings of the literature in a situation where limits are considered. The numerical results are presented graphically, providing a comprehensive analysis of the variables impacting fluid characteristics, including temperature and velocity. Interestingly, this work shows that a rise in the porosity parameter causes temperature profiles to rise and velocity to decrease. Moreover, a drop in velocity is linked to a rise in the Prandtl number. Furthermore, the influence of surface friction is diminished by including the porosity parameter. Moreover, a rise in the heat transmission rate at the surface can be observed.

Green Open Space Design in Papan Island Township Arrangement

: The purpose of open space is as a forum for organizing activities that are not only limited to human activities but also as a forum for nature conservation Papan Island has the potential as a tourist destination with its cultural wealth and biodiversity, by creating a space for tourists and still paying attention to the needs of the people of Papan Island and its environment, a tourist area will be created with the concept of Green Open Space (RTH) Method: The method used in this research is the Architectural design method. This method uses an analysis of the activities and needs of tourists and the community on Papan Island. Data obtained through interviews, observations, documentation, and literature studies Results and Discussion: This research makes the concept of shared space in architecture refer to an area or environment designed to be used and enjoyed together by a group of people. Based on the results of the analysis that has been carried out, the following design response will be made, namely making flexible openings such as large sliding door openings but at the same time can be closed. Conclusion This research shows that green spaces can be a key element in creating a healthier, more comfortable, and sustainable environment on Papan Island:

Exact solution to band structures of one-dimensional viscoelastic functionally graded phononic crystals

In this article, longitudinal wave (P-wave) band structures of functionally graded viscoelastic phononic crystals (PnCs) with exponential distribution properties are analytically investigated via an exact method. Differing from the laminated model, displacement and stress vectors of normal incident P-wave are obtained exactly by utilizing a stress-transform technique and the state space method. According to the continuous condition and Bloch theory, the eigenvalue equation of band structure is derived by applying transfer matrix method. The storage modulus is considered to be frequency-dependent while the loss modulus is neglected for the consideration of components viscoelasticity. Dispersion curves, obtained from the calculation of eigenvalue equation, are validated by the results of exist laminated model and transmission spectra which are also present to reveal the propagation characteristic of normal incident P-wave. Numerical examples indicate that band width and center frequencies of band gaps can be effectively altered by changing magnitude of exponential function, ratio between initial modulus and final modulus. Other new band gaps are opened as well as wider band width are achieved with the increase of gradient index к . The exact analytical solution presented in this paper can be the benchmark for those approximation solutions.

Conquering the beyond Rule of Five Space with an Optimized High-Throughput Caco-2 Assay to Close Gaps in Absorption Prediction.

Current drug development tends towards complex chemical molecules, referred to as "beyond rule of five" (bRo5) compounds, which often exhibit challenging physicochemical properties. Measuring Caco-2 permeability of those compounds is difficult due to technical limitations, including poor recovery and detection sensitivity. We implemented a novel assay, with optimized incubation and analytics, to measure permeability close to equilibrium. In this setup an appropriate characterization of permeability for bRo5 compounds is achievable. This equilibrated Caco-2 assay was verified with respect to data validity, compound recovery, and in vitro to in vivo correlation for human absorption. Compared to a standard assay, it demonstrated comparable performance in predicting the human fraction absorbed (fa) for reference compounds. The equilibrated assay also successfully characterized the permeability of more than 90% of the compounds analyzed, the majority of which were bRo5 (68%). These compounds could not be measured using the standard assay. Permeability and efflux ratio (ER) were highly predictive for in vivo absorption for a large set of internal bRo5 compounds. Reference cut-offs enabled the correct classification of high, moderate, and low absorption. This optimized equilibrated Caco-2 assay closes the gap for a high-throughput cellular permeability method in the bRo5 chemical space.

Assessment of the estimation methods of Tmrt in semi-outdoor spaces in humid sub-tropical climates: An empirical study in Wuhan, China

Studies have been conducted on the mean radiant temperature (Tmrt) estimation methods using globe thermometers for measuring outdoor thermal environments in various climate regions. Yet, given the unique thermal environments of semi-outdoor spaces, these Tmrt estimation methods may not be appropriate for the spaces with shading effects. This study aims to assess the thermometric and radiative methods for Tmrt estimation in semi-outdoor spaces in humid sub-tropical climates, taking data from six-directional radiation measurements as validations. During the typical summer and winter days in Wuhan, China, the measurements were carried out in semi-outdoor spaces facing south and west, with an open square for comparison, including air temperature, humidity, wind velocity, black-globe temperature, and long- and short-wavelength radiation fluxes obtained from four-component net radiometers. It was found the maximum mean deviation of diurnal Tmrt values estimated by the black-globe thermometer method in semi-outdoor spaces was 7.1 °C, which exceeded the threshold required by ISO7726, where the shortwave radiation was regarded as the dominant interference factor. To improve the accuracy and cost-effectiveness of Tmrt estimation, we proposed linear empirical equations to calibrate the Tmrt estimated by black-global thermometer method that the root mean square error (RMSE) of the Tmrt deviations can generally vary from 2.22 to 2.72 °C. Contributing to the thermal comfort research, this study proposed an empirical method for estimating Tmrt in semi-outdoor spaces in humid subtropical climates, which can generate satisfactory results in accordance with ISO7726 standards with cost-effective instrumentation.

A Steering-Vector-Based Matrix Information Geometry Method for Space–Time Adaptive Detection in Heterogeneous Environments

Plagued by heterogeneous clutter, it is a serious challenge for airborne radars to detect low-altitude, weak targets. To overcome this problem, a novel matrix information geometry detector for airborne multi-channel radar is proposed in this paper. The proposed detector applies the given steering vector and array structure information to the matrix information geometry detection method so that it can be used for space–time adaptive detection. While improving the detection performance, the matrix information geometry detector’s original anti-clutter advantage is enhanced as well. The simulation experiment results indicate that the proposed detector has advantages in several of the properties related to space–time adaptive detection, while its computational complexity does not increase significantly. Moreover, experiment results based on the measured data verify the superior performance of the proposed method. Sea-detecting data-sharing-program data, mountaintop data, and phased-array radar data are employed to verify the performance advantage of the proposed method in heterogeneous clutter and the ability for weak target detection.

Advancing estimation techniques and their applications in engineering and medical data analysis through novel continuous and discrete linear failure rate distribution extension

In this paper, we present a new heavy-tailed distribution called the heavy-tailed linear failure rate (HTLFR) distribution. Various statistical properties of the proposed distribution are derived, including the quantile function, the median, the ordinary moments, the moment generating function, the incomplete moments and the conditional moments. Some actuarial measures such as value at risk, expected shortfall, tail value at risk, tail variance and tail variance premium are calculated. Three different methods of estimation such as the maximum likelihood method, the maximum product spacing method and the Bayesian method as well as some simulation results for the model parameters of the HTLFR distribution under complete samples are examined. The results of the real data set show that the proposed distribution has greater flexibility and has been empirically evaluated under complete data. Discrimination analysis was employed to ensure fairness, equity, and accuracy in decision-making processes for selecting the best model, comparing the proposed distribution with known distributions. A discrete analog of the HTLFR distribution is proposed.

Validation of a Hybrid Domain Overlapping Coupling Between SAM and CFD Against the TALL-3D Transients

The system thermal-hydraulic (STH) code SAM has been coupled to the computational fluid dynamics (CFD) code Simcenter STARCCM+ utilizing a hybrid domain overlapping coupling method in space and an explicit coupling in time. The coupling aims to extend the STH code’s applicability to scenarios where local momentum and energy transfers are important yet difficult for STH standalone models to capture, such as three-dimensional (3D) mixing and thermal stratification. The coupling method’s numerical stability was previously verified against multiple test cases including two closed-loop configurations, and it was validated against a double T-junction experiment with 3D scalar mixing. In the present work, the method is validated against the TALL-3D STH/CFD coupling benchmark facility. TALL-3D is a liquid-metal facility with a large, pool-type enclosure (test section) that exhibits 3D flow effects to be modeled by a CFD code. The rest of the system exhibits approximately one-dimensional behavior that is well predicted by a STH code. First, a STAR-CCM+ CFD model of the 3D test section is validated against experimental temperature data. Then a SAM-STARCCM+ coupled model is validated against six different TALL-3D steady states and includes SAM standalone results for comparison. Last, the coupled model is validated against two TALL-3D transients: one exhibiting flow reversal in the test section and one exhibiting nonlinear, limit cycle oscillations (LCOs). For the first transient, the SAM-STARCCM+ coupled model properly predicts an increase in the test section’s inlet temperature during flow reversal, and this increase is not predicted by the SAM standalone model. The coupled model also better predicts initial flow recovery and subsequent oscillations as the system approaches a final natural circulation state. For the second transient, no true final steady state is observed due to LCOs. Neither the SAM-STARCCM+ coupled model nor the SAM standalone model can perfectly capture the experiment’s changing oscillation frequency during the transient. Nevertheless, the coupled model does reproduce the general oscillatory feedback observed. This is a significant achievement because the present coupling only uses an explicit coupling in time, as opposed to a tighter, semi-implicit coupling. In comparison, STH/CFD coupling efforts previously performed by other authors required a semi-implicit coupling to obtain similar results to this work. The strengths of the novel coupling scheme validated in the present paper lie in the superior convergence characteristics and the much simpler, nonintrusive implementation.

Shopping Mall Site Selection Based on Consumer Behavior Changes in the New Retail Era

As a product of the development of e-commerce over a specific period of time, the “new retail model” breaks the barriers between the traditional retail industry and e-commerce. Supported by Internet technology, it builds a new business model of “physical store + e-commerce + logistics” through the integration of online, offline, and logistics, which also leads to a great change in consumer behavior. Therefore, in order to meet consumer demand and achieve the long-term development of shopping malls, while taking into account the fair allocation of urban space resources, the indicators and methods of shopping mall site selection evaluation in the new retail era will be significantly different from traditional shopping mall site selection decisions. In this paper, the Wuhan East Lake Hi-Tech Zone is selected as the research object, and a comprehensive AHP-GIS assessment model is proposed. By investigating the impact of consumers’ behavioral changes on shopping mall location in the new retail era, a suitability evaluation system containing eight evaluation indicators is constructed, and the weights of each factor are determined using hierarchical analysis. At the same time, GIS is used to process the spatial analysis of the indicators, and combined with the weights of the factors, superposition analysis and quantitative research are carried out. Finally, based on the correlation analysis between ratings and customer flow, the suitability evaluation results are further supported in order to provide a more objective and scientific basis for the location of shopping malls from the perspective of the change in consumer behavior under the new retail model, and to put forward universal suggestions for the construction and development of shopping malls in the future.

Study on the Color Design of Elderly Space based on Design Color Science

The article applies the principle of art color science, through the analysis of the physiological and psychological characteristics of the elderly group and the various feelings of the color environment of the housing interior space, and carries out a series of research on the color matching method of the housing interior space of the elderly. Artistic color theory is a theory about color, and as a research method, it takes "color" as the focus, not just as an ordinary or auxiliary element, but as the "center" to be considered. The researcher can identify the "central" element of color through the artwork, explore the history of color development, color techniques and expressions, color symbols, and cultural symbolism, as well as the symbolic meaning and significance of ethnicity, nation, or country implied by color in the artwork, Art colorism, as a theory and method of interpreting the artwork.

Accurate measurement method for parallel edge spacing of sheet metal parts in aviation manufacturing

A new method, to our knowledge, is proposed to achieve high-precision measurement of parallel edge spacing for sheet metal parts in the complex industrial environment of aviation manufacturing. First, the sub-pixel edges of sheet metal parts are extracted by combining a what we believe to be a novel adaptive rolling bilateral filter and a sub-pixel edge detection algorithm based on the Canny–Steger algorithm. Then, the acquired edge data are denoised by using the clustering algorithm. Finally, a parallel line fitting algorithm, which combines an improved K-medoids algorithm with composite constraints on points and slopes, is proposed to calculate the parallel edge spacing. The results show that the method is robust to introducing noise in the edge data due to uneven illumination and various types of defects such as wear, scratches, and stains. The detection accuracy is high, with an average detection error of only 0.015 mm.

A two-stage clonal selection algorithm for local feature selection on high-dimensional data

Various evolutionary computation algorithms have shown their excellent performance for high-dimensional feature selection (FS). However, most of current FS methods choose a global feature subset and ignore the correlations between feature subsets and sample subspaces, which limits the performance of methods in the sample space with different probability distributions. To solve the issue, we propose a two-stage clonal selection algorithm for filter-based local feature selection (TSCSA-LFS) that integrates symmetric uncertainty and a discrete clonal selection algorithm with three contributions. First, unlike conventional feature selection methods, TSCSA-LFS introduces local sample behaviors and assigns subsets of features for different sample regions. Second, an improved discrete clonal selection algorithm is developed for searching relevant features, which contains mutual information-based individual initialization, a differential evolution-based mutation strategy pool and a local search technique. Third, a two-part antibody representation is employed for automatical adjustment of the weight-related parameter. Our method shows the promising experimental results compared with well-known global FS and clonal selection-based local FS methods on fourteen high-dimensional datasets. For instance, our method can obviously outperform local FS, filter-based and hybrid methods on at least nine datasets

Phase space analysis of semiconductor laser dynamics

The dynamics of semiconductor lasers are modelled in the time domain using a pair of differential equations known as rate equations. The analysis, based on temporal solutions of these equations, yields practical results utilised in various applications. Alternatively, an analysis employing the phase space method, a well-established analytical tool in applied mathematics, provides a more comprehensive perspective on semiconductor laser dynamics. The main purpose of this paper is to provide a detailed and intuitive introduction to phase space analysis in the context of semiconductor laser dynamics. The goal is to offer an easily comprehensible description of the mentioned method, placing emphasis on the graphical representation and physical interpretation of the results. The method effectiveness is shown through its application to selected practical problems. Furthermore, semiconductor laser dynamics can be treated as an illustrative example, showcasing the applicability of the method, which can be readily extended to other types of lasers or even more advanced dynamic systems.

Eddy–Internal Wave Interactions: Stimulated Cascades in Cross-Scale Kinetic Energy and Enstrophy Fluxes

Abstract The interactions between oceanic mesoscale eddies, submesoscale currents, and internal gravity waves (IWs) are investigated in submesoscale-resolving realistic simulations in the North Atlantic Ocean. Using a novel analysis framework that couples the coarse-graining method in space with temporal filtering and a Helmholtz decomposition, we quantify the effects of the interactions on the cross-scale kinetic energy (KE) and enstrophy fluxes. By systematically comparing solutions with and without IW forcing, we show that externally forced IWs stimulate a reduction in the KE inverse cascade associated with mesoscale rotational motions and an enhancement in the KE forward cascade associated with divergent submesoscale currents, i.e., a “stimulated cascade” process. The corresponding IW effects on the enstrophy fluxes are seasonally dependent, with a stimulated reduction (enhancement) in the forward enstrophy cascade during summer (winter). Direct KE and enstrophy transfers from currents to IWs are also found, albeit with weaker magnitudes compared with the stimulated cascades. We further find that the forward KE and enstrophy fluxes associated with IW motions are almost entirely driven by the scattering of the waves by the rotational eddy field, rather than by wave–wave interactions. This process is investigated in detail in a companion manuscript. Finally, we demonstrate that the stimulated cascades are spatially localized in coherent structures. Specifically, the magnitude and direction of the bidirectional KE fluxes at submesoscales are highly correlated with, and inversely proportional to, divergence-dominated circulations, and the inverse KE fluxes at mesoscales are highly correlated with strain-dominated circulations. The predominantly forward enstrophy fluxes in both seasons are also correlated with strain-dominated flow structures.

Exploration of and Inspiration from Research Hotspots and Key Methods of Age-Friendly Green Spaces from a Global Perspective

Exploration of and Inspiration from Research Hotspots and Key Methods of Age-Friendly Green Spaces from a Global Perspective

Mathematical Techniques for Computing the Reliability of a Parallel-series System of Order (2,3,1) under Rayleigh Failure Laws

Some well-known mathematical techniques have been used to compute the reliability of a parallel-series system of order (2,3,1). The system is composed of four units labelled as A, B, C and D. The configuration involves two parallel subsystems: the first containing units A, B and C arranged in series and the second comprising a single unit D. The failure rate of units is assumed to follow the Rayleigh distribution. With the use of the decomposition method, cut set method and event space method, expressions for both reliability and Mean Time to System Failure (MTSF) have been derived. By considering all units to be identical, the reliability measures have been obtained numerically for specific parameter values. The trends of these measures have been represented graphically to understand the effect of parameters. The study has its practical significance in assessing the reliability of solar panel system. . KEYWORDS :Parallel-series System, Rayleigh failure laws, Decomposition method, Cut set method, Event space method.

Nonlinear Loads Modelling and Harmonics Analysis: A Review

Abstract: In modern life, the applications of nonlinear loads are increasing, especially electronic loads, such as computers, monitors, and battery chargers. Moreover, the usage of semiconductors has increased in modern lighting systems, such as LED lamps and dimmers which are used to control the lighting level. Nonlinear loads may also be in the form of variable speed drive or arc furnace loads. Due to the spread of nonlinear loads, large amounts of harmonics are generated. To study the harmonics of nonlinear loads, it is essential to represent nonlinear loads by their equivalent models in the simulation programs. This paper presents a comprehensive review of modeling methods of nonlinear loads, including time domain methods, frequency domain methods, and state space methods. Equivalent circuits are presented for different types of nonlinear loads, including static loads, dynamic loads and arc furnace loads. The paper also presents the harmonic analysis performed by the Fourier transform of different types of nonlinear loads, including harmonic percentage and its angle. This paper is considered as a comprehensive reference for researchers and engineers to model nonlinear loads and is useful in power system planning for connecting nonlinear loads where mixing nonlinear loads of similar harmonic profiles causes worse situations. Moreover, knowing the nonlinear load profile will help in the suitable mixing of linear loads to achieve lower harmonics levels.

Space-time error estimates for approximations of linear parabolic problems with generalized time boundary conditions

Abstract We first give a general error estimate for the nonconforming approximation of a problem for which a Banach–Nečas–Babuška (BNB) inequality holds. This framework covers parabolic problems with general conditions in time (initial value problems as well as periodic problems) under minimal regularity assumptions. We consider approximations by two types of space-time discretizations, both based on a conforming Galerkin method in space. The first one is the Euler $\theta -$scheme. In this case, we show that the BNB inequality is always satisfied, and may require an extra condition on the time step for $\theta \le \frac 1 2$. The second one is the time discontinuous Galerkin method, where the BNB condition holds without any additional condition.

An Unconditionally Stable Numerical Method for Space Tempered Fractional Convection-Diffusion Models

An Unconditionally Stable Numerical Method for Space Tempered Fractional Convection-Diffusion Models