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Graphene, celebrated for its remarkable atomic structure, stands as a key material in diverse fields such as nanoelectronics and materials science. This paper presents a thorough investigation into the metric dimensions of graphene, emphasizing its unique spatial properties and their broad implications. We analyze how these metric dimensions affect graphene’s electrical, thermal, and mechanical behavior in various applications. Our study delves into the physical mechanisms behind these properties, including atomic interactions, lattice dynamics, and external factors like temperature and pressure.

The metric dimension of a graph G is the minimum cardinality of a subset $W\subseteq V(G)$ such that every pair of distinct vertices $u,v\in V(G)$ is uniquely identified by their distance vectors relative to W and the resolving set, ensures for any $u,v\in V(G)$ with $u\ne v$, there exists a vertex $w\in W$ such that $d(u,w)\ne d(v,w)$, where d denotes the distance function in G. In this work, we will determine the metric dimension and Resolving set. However, these findings pave the way for innovative applications in electronics, composites, and beyond.

Computer networks are important infrastructures required by many modern corporations today. Maintaining a reliable computer network becomes an important issue in daily business operations. A computer network usually consists of components (including links or vertices) that may have several states due to failure, partial failure or maintenance, making it a multi-state computer network (MCN). This paper proposes a novel approach to create an optimal component quality plan in MCN. Finding the optimal component quality plan for an MCN requires searching for an optimal plan such that each component in the network has the proper level of quality while the network maintains highly reliable functionality. Because the costs of quality components are diversified, an appropriate plan for component quality distribution cannot only greatly reduce the cost of network installation but also maintain the network reliability. Another important consideration is that high-quality and expensive components may not increase network reliability if they are not placed appropriately. A novel heuristic approach is proposed to efficiently search for such plan. A comparison with the implicit enumeration method is conducted. The results show that the proposed approach is very effective and efficient. Some numerical examples are illustrated and explained in detail in this paper.

The emphasis on structural design of miniaturized machine tool (mMT) used in micro-machining process is different from that of conventional machine tool due to requirement of higher precision and stable performance. In this paper, structural modeling and simulation of 3-axis vertical micro-end-milling system is presented. Based on different components combination, three models of linear multi-degree-of-freedom vertical milling systems are constructed theoretically using high precision stages. The most suitable model is chosen by volumetric error calculation. Finite element method (FEM) is used for simulation of those numerical solid models. Static and dynamic analysis with different joint stiffness and loads is simulated by ANSYS. Prototype model is assembled according to the selected structure. Finally, surface roughness of the bottom of micro slots, which are machined by prototype model, is analyzed to verify the performance of mMT.

The heavy duty diesel engine must have a large output for maintaining excellent mobility. In this study, a three-dimensional finite element model of a heavy-duty diesel engine was developed to conduct the stress analysis by using property of CGI. The compacted graphite iron (CGI) is a material currently under study for the engine demanded for high torque, durability, stiffness, and fatigue. The FE model of the heavy duty diesel engine section consisting of four half cylinders was selected. The heavy duty diesel engine section includes a cylinder block, a cylinder head, a gasket, a liner, a bearing cap, bearing and bolts. The loading conditions of engine are pre-fit load, assembly load, and gas load. A structural analysis on the result was performed in order to optimize on the cylinder block of the diesel engine.

In this research, hull structure of Ray-type Underwater Glider (RUG) that could be a next generation unmanned vehicle was studied. RUG is capable of long-term operation at higher speeds than conventional cylindrical underwater gliders due to its ray shaped body composed of dual buoyancy engine. For long-term operation, it is necessary to develop a lightweight control housing and battery case. For this reason, the carbon fiber container was used to be lighter and stronger than duralumin used in the past. Through the stress and buckling analysis, it was shown that the container was able to withstand the pressure of 200 m which is the target water depth with the safety ratio of about 1.8 times. Using a carbon composite material, the mechanical strength can be maintained while reducing the weight of the pressure vessel by more than 40% compared with the high tensile aluminum material.

Graphene has been considered one of the most important materials for many applications due to its unique electronic structure, physical and chemical properties. Graphite flakes are the main source of graphene oxide which can be transformed to graphene after reduction. The effect of irradiation on graphene oxide has been rarely studied, only few studies dealing with the irradiation of graphene oxide with gamma radiation were reported. The effect of irradiation of graphene oxide with gamma ray doses (low linear energy transfer) has been previously studied. It was found that there are no changes in the crystalline structure of graphene oxide after irradiation. Graphene oxide was prepared by modified Hummer’s method. The scanning electron microscopy image of the obtained sample suggests the presence of both single and multilayer graphene oxide sheets. The structural measurements for the graphene oxide samples with high linear energy transfers were carried out after irradiations with different doses of alpha particle (9.30–479.90 Gy). The effect of irradiation on oxygen functional groups of graphene oxide was followed by Fourier transforms infra-red spectrometer. Moreover, the irradiation effect on the lamellar space of graphene oxide layers was measured by X-ray diffraction. It was found that the d-spacing of graphene oxide was decreased after alpha particles irradiation with different doses. The effect of irradiation on dielectric constant and conductivity of graphene oxide samples was measured in the frequency range (200 Hz–1.00 MHz). The dielectric measurements show less dependence on irradiation doses. The graphene oxide sample can be used as radiation dosimeter for $\alpha$-particles in the range of the low irradiation doses.

In this work, Sr-substituted samples of single-phase spinel monoferrites with chemical formula ${\mathrm{\text{Ba}}}_{1-x}{\mathrm{\text{Sr}}}_x{\mathrm{\text{Fe}}}_2{\mathrm{\text{O}}}_4$ (x = 0.00, 0.33, 0.67, 1.00) were synthesized using sol–gel auto-combustion method. In order to confirm the single-phase formation of these samples, a sample (x = 0.00) was chosen for heat treatment at different temperatures (100, 300, 400, 600 and $700^{\circ }\mathrm{\text{C}}$) for 4 h. The heat treated sample was then investigated by X-ray diffraction (XRD) analysis and results showed that a single-phase sample can be successfully synthesized at a temperature of $600^{\circ }\mathrm{\text{C}}$, which is much lower than that reported in earlier literature for synthesis of same structured samples. All the synthesized samples were then sintered at $700^{\circ }\mathrm{\text{C}}$ for 4 h to achieve better crystallinity. From XRD patterns, lattice parameters, cell volume and XRD density as a function of Sr-substitution were calculated. Scanning electron microscopy (SEM) results showed that the grain size increased as the temperature was increased. Fourier transform infrared spectroscopy (FTIR) results confirmed the single-phase spinel monoferrites at $700^{\circ }\mathrm{\text{C}}$. From M–H loops (x = 0.0, 0.33, 0.67 and 1.00), different magnetic parameters such as saturation magnetization $(M_s)$, remanance $(M_r)$, coercivity $(H_c)$ and magnetic moment $(n_B)$ were calculated. Magnetocrystalline anisotropy constant and Y–K angles of Sr-doped Ba monoferrites were also calculated. In addition, the variation of different dielectric parameters (real permittivity, imaginary permittivity, real permeability, imaginary permeability, ac conductivity and loss tangent) as a function of frequency (1–6 GHz) has been discussed in this work. The results suggest that the synthesized materials have many advantages over previously reported single-phase spinel monoferrites.

The purpose of this study is to reduce the weight of elevator components in order to save energy and apply the findings to the new drive-type elevator system. Structural design has been carried out for two lightweight elevator models in which the damped aluminum laminate (DAL) and carbon fiber reinforced plastics (CFRP) are utilized for the elevator walls, respectively. The structural designs of the new elevator walls are based on the bending stiffness of the existing steel walls. The aluminum elevator model is designed to exhibit a bending stiffness similar to that of the existing steel elevator, while the CFRP model is designed to possess 20% of the existing wall bending stiffness considering that the tensile strength in the fiber direction is about nine times higher than that of the existing structural steel material. DAL and CFRP are applied to the elevator walls, respectively, and aluminum sandwich structures are applied to the ceiling and platform of two kinds of lightweight elevator models. It has been ascertained that the aluminum elevator model is about 40% lighter than the existing steel elevator, and the CFRP elevator model is about 50% lighter than the existing elevator. In order to evaluate the structural integrity of the newly designed elevator model, the criteria presented in the elevator inspection guideline are applied. The designed elevator model is confirmed to satisfy the strength and stiffness criteria presented in the elevator inspection parameter.

The objective of this study is to enhance the efficiency of urban air mobility (UAM) air transportation by determining the optimal design, materials, and processes of seven different manufactured fiber-reinforced plastics (FRP), and to confirm their applicability for next-generation UAM aircraft seats. Structural designs for the aircraft seat models were carried out using carbon fiber-reinforced plastic (CFRP), glass fiber-reinforced plastic (GFRP), and GFRP chop materials, employing Autoclave, Hot-press, and vacuum-assisted resin transfer molding (VaRTM) processes, resulting in a total of seven FRP configurations. It was confirmed that CFRP seats were 50% lower weight than aluminum models, while GFRP seats showed a 30% reduction. Although Autoclave processing resulted in the highest tensile strength at 985MPa, VaRTM processing also produced strength levels comparable to Autoclave processing. Structural integrity assessments of the seat models, utilizing the Korean aviation standards (KAS), confirmed that the designed seat models exhibited no failure or deformation under the conditions required by the technical standards. This study provides insights into the potential application of the seven types of FRP materials in the design of aircraft seats, offering weight reduction benefits and meeting the structural integrity requirements outlined by KAS.

In this paper a new thinning algorithm for binary patterns is presented. The algorithm is based on an iterative controlled removal procedure working on entire regions of the pattern. The thinning process permits to obtain skeletons retaining important specificities of the pattern useful for robust structural descriptions. The experimental results carried out on typewritten and handwritten characters point out the efficacy of the algorithm with respect to other techniques in literature.

Signing is a complex and highly variable process. It results from simple bodily motions of a ballistic nature whose combined effects produce the fundamental components of the signature. Therefore, signature verification can be performed by adopting local verification strategies for the detection of personal characteristics in fundamental components.

In this paper, an on-line component-oriented signature verification system is presented. During the training phase, the set of fundamental components of each signer is derived and a suitable component-oriented knowledge-base is created by an automated technique. The verification is accomplished through a step-wise process. In the first step the structural organization of the signature is checked. In the second step each component is examined using spectral analysis. The experimental result shows the effectiveness of this approach compared with other techniques in the literature.

This research shows a structural voltage stability analysis of a distribution network incorporating large-scale solar photovoltaic power plant. Detailed modeling of the transmission network and photovoltaic systems is presented and a differential-algebraic equations model is developed. The resulting system state and load-flow Jacobian matrix are reorganized according to the type of the bus system in place of the standard injected complex power equations arrangement. The interactions among system buses for loading tests and solar photovoltaic power penetration are structurally scrutinized. Two-bus bifurcations are revealed to be a predecessor to system voltage collapse. The investigation is carried out by using bifurcation diagrams of photovoltaic generation margin, load-flow analysis, short-circuits, photovoltaic farm disconnections and loading conditions. Furthermore, evaluation of voltage stability reveals that the dynamic component of the voltage strongly depends on fault short-circuit capacity of the power system at the bus, where, the solar system is integrated. The overall result, which encompasses the views from the presented transmission network integration studies, is a positive outcome for future grid integration of solar photovoltaic in the Tunisian system. Tunisia’s utilities policies on integration of solar photovoltaic in distribution network is expected to benefit from the results of the presented study. Moreover, given the huge potential and need for solar photovoltaic penetration into the transmission network, the presented comprehensive analysis will be a valuable guide for evaluating and improving the performances of national transmission networks of other countries too.

A number of recent studies have focused on structural and functional analysis and simulation of biochemical pathways, and it suggested that these structure-oriented analysis methods could be greatly helpful for the understanding of the metabolism. Among several structural analysis methods, Petri nets analysis (PNA) has a visual representation that facilitates users' comprehension and thus is employed in this study. The main results in the present paper are: (1) an in silico model of the metabolism of riboflavin production in bacillus subtilis based on PNA; and (2) a study with structural analysis. The obtained invariants are analyzed and classified based on their structural and functional capabilities.

In the this study, we focus on the growth of a metal-organic creatininium borate (CRB) single crystal for third-order nonlinear optical (NLO) applications. Optically transparent & wide optical band gap single crystals of CRB were successfully harvested by adopting a slow evaporation solution technique (SEST) at a constant 40${}^{\circ }$C temperature. The structural identification and lattice parameters of the grown sample were determined by powder X-ray diffraction (PXRD) using Rietveld analysis by FullProf Suite software. The occurrence of vacancy/interstitial defects produced during growth was investigated by high-resolution X-ray diffraction (HRXRD) using omega scan arrangement. A single peak with lower full width half maxima (56.4 arc s) was obtained from the scan which suggests that there were no grain boundaries for the grown crystal. Surface morphology and its features such as concentration of dislocations and defect sites on the as-grown sample were scrutinized using the etching technique. The optical band gap and UV–vis cut-off were examined and found to be 5.39 eV and 230 nm, respectively. Photoluminescence characteristics of the crystal show an emission at 377 nm upon excitation with a wavelength of 336 nm. The presence of radiative and non-radiative transitions inside the crystal due to excitation upon 266 nm laser was identified using time-resolved photoluminescence. Thermal stability and decomposition temperature of the compound were obtained by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The third-order nonlinearity of the crystal was determined by Z-scan measurement technique with a femtosecond Ti-sapphire laser.

Decreased flexural and buckling capacity of composite structures due to the development of fatigue cracks is a serious issue in a variety of fields. This paper discusses the buckling capacity and piezoelectric material enhancement of cracked column structures. A model of the rotational discontinuity at the crack location is used to develop analytical buckling solutions and the effect of crack location and intensity on the buckling capacity of the damaged columns is investigated. Small piezoelectric patches are employed to induce local moments to compensate for the decreased buckling capacity of column structures, using a mechanical model coupled with piezoelectric strain-voltage relations. The voltages required to enhance the buckling capacity are analytically determined and the general relationship between crack location and voltage developed. The primary advantage of the piezoelectric-based repair approach presented is the ability to use a single small patch, with different applied voltages, to repair cracks of a wide variety of depths, intensities and locations passive design solutions would require custom designs to restore the axial load capacity for each case.

Simply supported bridges are the main bridge types in many transportation systems, and their damage can significantly reduce their load-carrying capacity. To detect possible damage, the time history and spatial distribution of the static responses of bridges (deflection, rotation, and strain influence lines/deformation curves) have recently been proposed as important indicators due to their good local damage detection ability and low testing cost. This paper attempts to establish connections between different static curve-based damage indicators through the various forms of Maxwell-Betti’s law. Damage indicators related to seven static curves are then rewritten as a unified framework. The framework states that all these static curves are directly related to the flexural stiffness distribution of the main girder for the simply supported bridge. Then, the theoretical formulations for the difference between the static curves of bridges in intact and damaged states are derived, and the response difference surfaces (RDSs) are plotted to visualize the sensitivity of different static curves to damage. Sensor placement suggestions for stiffness degradation evaluation are presented based on the damage sensitivity analysis at the end of this paper. The results of this study provide comprehensive theoretical support for static response-based damage identification of simply supported bridges.

Electric wheelchairs developed so far have difficulties for elderly people to use, because of their bulkiness and heavy weight. To address this problem, this study presents a design for the construction of an electric wheelchair with an application of light duty materials at frame and a foldable structure that can be easily loaded in a narrow space. A structural analysis was performed to evaluate the structural safety of the foldable wheelchair. For the purpose of analysis, a carbon composite was used as the material for the frame; Structure Mechanics Module of COMSOL Multiphysics was used as the analysis software; and for the boundary condition, the lower part of the body frame was fixed, and a load of 150kg was applied to the upper part of the wheelchair. According to the results of the structural analysis, a maximum displacement of 2.869mm occurred at the handle where the carbon composite was applied, and tensile and compressive stress of 103MPa and 107.3MPa, respectively, were measured at the seat part of the wheelchair where the load was applied. The safety factors were 7.5 and 5.5 for tensile stress and compressive stress, respectively. A maximum variation of 0.0872mm occurred at the aluminum wheel shaft, and a maximum variation of 0.2046mm occurred at the joint. The maximum stress was 116.3MPa that corresponded to a safety factor of 2.66; this indicates that the wheelchair can be considered to be structurally safe as the safety factor exceeds the initial target of 2.

A butterfly valve of large diameter is commonly used as control equipments in applications where the inlet velocity is fast and the pressure is relatively high. Because the size of the valve is too large, it's too difficult to conduct testing experiment in a laboratory. In this paper, the numerical simulation using commercial package-CFX and ANSYS was conducted. In order to perform fluid analysis and structural analysis perfectly, large valve models are generated in three dimensions without much simplification. The result of fluid analysis is imported to structure analysis as a boundary condition. In addition, to describe the flow patterns and to measure the performance when valve are opened for various angles, the verification of the performance whether the valve could work safely at these different conditions or not was conducted. Fortunately, the result shows that the valve is safe in a given inlet velocity of 3 m/s, and it's not necessary to be strengthened anywhere. In the future, the shape of valve disc can be optimized to reduce the weight, and also to make the flow coefficient be closer to the suggested level.

A critical review of the current state of the art of the computing practices adopted by the earthquake engineering community is presented. Advanced computational tools are necessary for estimating the demand on seismically excited structures. Such computational methodologies can provide valuable information on a number of engineering parameters which have been proven essential for earthquake the engineering practice. The discussion extends from the finite element modeling of earthquake-resistant structures and the analysis procedures currently used to future developments considering the calculation of uncertainty and methodologies which rely on sophisticated computational methods. The objective is to provide a common ground of collaboration between the earthquake engineering and computational mechanics communities in an effort to mitigate future earthquake losses.

Structural performance of unidirectional composites (UD) is directly dependent on its ingredient’s properties, ply configurations and the manufacturing effects. Prediction of mechanical properties using multiscale manufacturing simulation and micromechanical models is the focus of this study. Particular problem of coupled dual-scale deformation-flow process such as the one arising in RTM, Vacuum-Assisted Resin Infusion (VARI) and Vacuum Bag Only (VBO) prepregs is considered. A finite element formulation of porous media theory framework is employed to predict the element-wise local volume fractions and the deformation of a preform in a press forming process. This formulation considers coupling effects between macro-scale preform processes and mesoscale ply processes as well as coupling effects between the solid and fluid phases. A number of different micromechanical models are assessed and the most suitable one is used to calculate mechanical properties from volume fractions. Structural performance of the “deformed” geometry is then evaluated in mechanical analysis. An integrated platform is designed to cover the whole chain of analysis and perform the properties’ calculation and transfer them between the modules in a smooth mapping procedure. The paper is concluded with a numerical example, where a compression-relaxation test of a planar fluid filled prepreg at globally un-drained condition is considered followed by a mechanical loading analysis. The development is user friendly and interactive and is established to enable design and optimization of composites.