Optimal Geometric Configuration Research Articles

Zn(II), Mn(III), and Co(III) complexes of Schiff base derived from 2‐hydroxy‐1‐naphthaldehyde: Synthesis, spectral surveys, single crystal structure studies, Hirshfeld surface analysis, density functional theory calculation, molecular electrostatic potential, and molecular docking evaluations

A new series of transition metal complexes of bidentate Schiff base compound derived from 2‐hydroxy‐1‐(2‐methoxyethylimino)‐naphthalene (HL) were synthesized and characterized using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), and UV–vis spectroscopies. X‐ray single crystal structures of Zn(II), Mn(III), and Co(III) complexes (1–4) have also been determined, and it was indicated that these Zn(II) and Co(III) complexes (1, 4) are in an octahedral geometry. Whereas, it was found that the Zn complex (2) is in quite a regular tetrahedral environment. Also, the Mn center in complex (3) is ligated by two azomethine nitrogen atoms, two ligand oxygen atoms, and one Cl atom of metal salt forming five coordinated tetragonal pyramid geometry around the Mn atoms. The cyclic voltammetry of the complexes specifies an irreversible redox behavior for all complexes (1–4). Next, DFT/B3LYP theoretical method was used to determine the optimal geometrical configurations and comparison between experimental and theoretical data, as well as for calculations of molecular electrostatic potential, highest‐occupied molecular orbital (HOMO)‐lowest‐unoccupied molecular orbital (LUMO) energy values of selected compounds. The study of non‐covalent interactions was done by Hirshfeld surface analysis using CrystalExplorer program. Furthermore, molecular docking inspection was carried out to study the binding affinity of the tested complexes towards protein B‐cell lymphorna (PDB ID: 4LXD). Using the results obtained from the molecular docking and the summarized interaction of the binding processes, these structures show the validity of effective inhibition against liver cancer.

Utilization of a Genetic Algorithm to Identify Optimal Geometric Shapes for a Seismic Protective Barrier

The utilization of seismic barriers for protection against the hazardous impact of natural or technogenic waves is an extremely promising emerging technology to secure buildings, structures and entire areas against earthquake-generated seismic waves, high-speed-transport-induced vibrations, etc. The current research is targeted at studying the effect of seismic-barrier shape on the reduction of seismic-wave magnitudes within the protected region. The analytical solution of Lamb’s problem was used to verify the adopted numerical approach. It was demonstrated that the addition of complementary geometric features to a simple barrier shape provides the possibility of significantly increasing the resulting seismic protection. A simple genetic algorithm was employed to evaluate the nontrivial but extremely effective geometry of the seismic barrier. The developed approach can be used in various problems requiring optimization of non-parameterizable geometric shapes. The applicability of genetic algorithms and other generative algorithms to discover optimal (or close to optimal) geometric configurations for the essentially multiscale problems of the interaction of mechanical waves with inclusions is discussed.

Increasing sensitivity of the electrostatic field mill sensor by determining its optimal configuration

The object of research is the process of measuring the strength of the electrostatic field for a low dynamic range (from 0 to 1 kV/m). This study is aimed at increasing the sensitivity of the sensor of the electrostatic field mill (EF) by determining its optimal geometric configuration, which will reduce the error of measuring the electrostatic field strength. To establish the actual value of the induced current, a computer model was built and simulation modeling of the EF sensor was carried out. On the basis of the constructed computer model, studies of the EF sensor were carried out to determine the numerical value of the induced current. As a result, it was established that the occurrence of edge effects leads to the appearance of methodological error, which occurs due to the fact that the average induced current is smaller compared to the calculated value. As a result of computer modeling of the EF sensor to determine the value of the optimal number of sectors, it was established that for the proposed design of the EF sensor, the optimal number of sectors is six. It was established that the optimal value of the distance between the sensitive plates and the shielded rotor should be in the range of 2.5–3 mm to ensure the maximum sensitivity of the EF sensor and its safe use. The determined optimal parameters of the EF geometric configuration will allow to form the necessary requirements for the construction of improved electrostatic field strength meters in a low dynamic range (from 0 to 1 kV/m). A promising direction of application of such devices in production will be the development of an additional system for monitoring the strength of the electrostatic field, which will allow to prevent the occurrence of a dangerous situation.

Optimized Design of Shell and Tube Heat Exchanger with Segmental Baffles

Heat exchangers are the apparatus which is widely used in various industries. They transmit heat among two or more fluid streams. Theoretical analysis done by Kern’s method has been done on Shell and tube heat exchanger with segmental baffle and then experimented in CFD to check Heat Transfer rate and pressure drop with varying number of baffles which is 6, 8 and 10, and by keeping all the rest of parameters constant. It is found that as the number of baffles increase heat transfer rate increases also pressure drop is increases significantly. To optimize model in next step, CFD analysis is has been done by varying baffle cut to 25%, 35% and 45% by keeping same number of baffles which found best in heat transfer rate in earlier Kern’s method. Other parameters like velocity, temperature, pressure and baffle numbers are kept constant. Results obtained from numerical solution are analysed extensively to get the effect of baffle cut on heat transfer rate and pressure drop on shell side. The pressing need of the heat exchanger industry, the tradeoff optimization between the pressure drop and the heat transfer coefficient has been studied to provide an idea to get effects of the change in two parameters, namely, baffle spacing and baffle cut simultaneously and observe how these two will affect the performance of an STHX. An attempt to find the optimum geometric configuration has been carried out with number of baffles. Increasing baffles for same length of shell and baffle cut increases from 25% to 35%, heat transfer rate increases. It is beneficial in elucidating that a higher heat transfer coefficient can be obtained for fewer baffles when coupled with the appropriate baffle cut. So selection of correct optimized shell and tube heat exchanger. The work is carried out for copper tube bundles and steel shell. So optimization of baffle cut with correct number of baffles and reduction in pressure drop studied with CFD tool.

A fast satellite selection algorithm for positioning in LEO constellation

In the near future, a much larger scale of low earth orbit (LEO) satellites will be deployed, and satellite selection is an effective way to overcome challenges to processing capability and channel limitation of receivers caused by superabundant satellites in view. However, existing algorithms do not take into account the fact that a large-scale LEO constellation satellite selection subset can be closer to the theoretical optimal configuration than the traditional brute force search and recursive algorithm computational overhead is too large for end devices. In this study, the solution of the minimum optimization problem of the GDOP (Geometric Dilution of Precision) under the condition of limited elevation angle is first analyzed to determine the optimal ratio configuration scheme of top and bottom satellites under the optimal geometric satellite positioning problem. Subsequently, a fast satellite selection algorithm is proposed, which selects a subset of satellites that meet the different numbers of observation satellites and is close to the optimal geometric configuration by geometric method. The comparative simulation shows that, in the 1586 LEO constellation system, the proposed algorithm has an average GDOP of 1.52 when the satellite subset size is 10 and 0.95 when the subset size is 30. Compared with the recursive, the Rotating Partition algorithm and the Quasi-optimal algorithm, the proposed algorithm achieves better accuracy when its size is not close to the total number of observable satellites.

Numerical analysis of a flat plate collector using different types of parallel tube geometry

To obtain improved thermal performance of flat plate solar collectors, the effect of square and rectangular riser tubes of a flat plate collector (FPC) were numerically investigated and compared with circular riser tube FPC in the present study. For this purpose, a three-dimensional numerical model for FPC collectors has been developed and simulated in CFD software ANSYS FLUENT. Transient thermal performance analysis is carried out to find out the optimum geometrical configuration of the FPC riser tube. The numerical results indicated that using the square-shaped riser tube in FPC improves the collector’s useful heat exchange rate as well as thermal efficiency as compared to the use of circular and rectangular riser tubes. There is a maximum 8.1% higher heat exchange rate of the collector with a square riser tube than a circular riser tube under the same operating conditions. The average efficiency of the collector with the circular tube is 65.95%, whereas the square tube has the highest efficiency of 70.44%. However, the pressure drops through the square and rectangular riser geometry are higher than the circular tube. By making a balance between enhanced heat exchange rate and increased pressure drop, the performance evaluation criterion was evaluated and the square-shaped riser tube having the highest value of 2.65 is better than the other configurations. The results clearly indicate that the collector’s performance is notably influenced by the shape of the riser tube, with a square shape yielding superior performance.

Optimizing graded metamaterials via genetic algorithm to control energy transmission

Optimization of functionally graded metamaterial arrays with a high dimensional and continuous geometric design space is cumbersome and could be accelerated via machine learning tools. Mechanical metamaterials can manipulate acoustic or ultrasonic waves by introducing significant dispersive and attenuative effects near their natural frequency. In this work, functionally graded structures are designed and optimized to combine the energy attenuation performance of multiple unit cells with varying frequency responses and to reduce the interlayer mismatch effects. Optimization through genetic algorithms avoids many local minima related to high dimensionality of the design space, but requires many iterations. A reduced order model (ROM) is applied, which can reproduce the transmission response traditionally calculated with FEM in a fraction of the time. Pairing GA and the ROM together, an array of 6 unit cells (with a total of 18 independent geometric design variables) is optimized to have stop bands with extended width and sharper boundaries. Symmetric functionally graded structures are determined to have optimal geometric configurations. Measured 3D printed features are projected onto the ROM solutions to quantify the effect of printing uncertainty on array performance. Repeatability error of ±20μm is determined to reduce the mean depth of the transmission stop band by a factor of 102 and introduce small shifts in center frequency and band width. Proposed methods to improve the resolution of accessible points in the ROM space, reduce sensitivity to geometric uncertainty, and add design freedom include introducing out-of-plane perforations and varying constituent materials using tunable filled resin systems.

Numerical analysis and optimization of adhesively-bonded single lap joints by adherend notching using a full factorial design of experiment

The objective of this study is to carry out experiments using the experimental design methodology to determine the optimal geometric configuration which improves the resistance of a single-lap joint with notched adherends subjected to uniaxial tensile load. On the sides of the adherends in contact with the adhesive layer, a longitudinal rectangular notch is introduced. A complete experimental design (15) of three factors at two levels: the adhesive thickness (tA), depth (dN) and extended length (LE) of the notch was used to determine their effects on strength of an adhesive joint. The response or dependent variable used was the resistance of a single lap joint (SLJ). Finite element (FE) analysis was conducted to investigate the effect of different notch parameters on the strength enhancement of the SLJs. A quadratic regression model with interaction is developed to relate the strength of an adhesive joint and the variables (tA, dN and LE). The regression model was validated using various statistical approaches. According to the ANOVA results, the model is highly significant and in good agreement with the experimental results. The quadratic regression model suggested was used for optimizing the resistance of the joint. The maximum joint strength occurs when the adhesive thickness is the smallest (left end) and when the adhesive thickness is the largest (right end) of the validated domain. The strength of SLJ increases when the notching parameters (dN and LE) increase in the validation zone. The numerical results show that to improve the resistance of an adhesive joint with notched adherend, it is necessary to minimize the thickness of the adhesive layer and to use notch with the highest depth and extension equal or greater than the overlap. The results show that using the adherend notching can significantly improve the load bearing capacity of SLJs.

Time-dependent water wave scattering by a marine structure consisting of an array of compound porous cylinders

Under the assumption of linear wave theory, a semi-analytical model is developed to address the time-dependent water wave scattering problem involving a marine structure consisting of several circular rigid vertical cylinders, each of which is surrounded by a thin cylindrical porous wall with a water region between the inner cylinder and the wall. The problem is tackled by applying the eigenfunction expansion approach. The energy dissipation relation is also derived for the system of compound cylinders. The principal focus of this work lies in locating the optimum geometrical configurations for which the wave forces acting on the structure are minimal along a given wave direction in the frequency domain. Subsequently, the time-dependent response of the structure under the impact of a Gaussian wave pulse is examined. The wavenumber at which the force acting on the inner cylinder is at its maximum is obtained for a given value of the porous-effect parameter. Moreover, the value of that corresponding wavenumber decreases as the magnitude of the porous-effect parameter increases. The model is also carefully validated numerically against results available in the existing literature.

Coiled quarter wavelength resonators for low-frequency sound absorption under plane wave and diffuse acoustic field excitations

To reduce their space requirement, quarter wavelength resonators are coiled up into a spiral to have the shape of a flat cylinder. The practical implementation of these resonators is tested using 3D printing, laser cutting and machining. Numerical simulations and impedance tube measurements are first compared for a normally incident plane wave excitation. This step allows to evaluate the effect of the resonator’s inlet diameter, internal wall thickness, overall height as well as its constitutive material. A series of samples are then 3D printed following the identified optimal geometrical configuration. An array of resonators is tested alone and in combination with a glass wool layer under diffuse acoustic field excitation in a small reverberation chamber. The obtained results show that coiled quarter wavelength resonators can provide large sound absorption at their lowest resonance frequency and under both considered excitations, even if the largest external dimension of the resonators is only 1/18th of the targeted acoustic wavelength.

Optimization of Conductive Fins to Minimize UO2 Fuel Temperature and Radial Temperature Gradient

To further the development of low-enriched uranium fuels, precedence has been placed on delivering the same amount of power while lowering the fuel temperature and radial temperature gradient. To address this, modeling efforts have resulted in a novel design featuring conductive fins of varying thermal conductivities and geometries inserted into the fuel matrix. These conductive inserts were not allowed to exceed 6% of the original fuel volume. This constraint was imposed due to other designs displacing 10% of fuel volume. A parametric study was performed that consisted of 2.56 million BISON simulations involving varying fin characteristics (i.e., fin thermal conductivity, number, and geometry) to determine the optimal geometric configuration for a desired amount of fuel volume displaced. The results from this study show that the thickness and length of each fin affect the fuel temperature and temperature gradient more than varying the number and thermal conductivity of the fins. The parametric study resulted in the development of an optimized combination to produce the lowest peak fuel temperature, lowest radial temperature gradient, and highest temperature reduction for the amount of original fuel volume displaced. The simulations presented in this work will eventually be compared with irradiation experiments of similar fuel designs at Idaho National Laboratory’s Advanced Test Reactor.

Optimal geometrical configuration and oxidation state of cobalt cations in spinel oxides to promote the performance of Li-O2 battery

Optimal geometrical configuration and oxidation state of cobalt cations in spinel oxides to promote the performance of Li-O2 battery

Bioinspired Z-scheme In2O3/C3N4 heterojunctions with tunable nanorod lengths for enhanced photocatalytic hydrogen evolution

Inspired by natural photosynthesis, Z-scheme heterojunction fabrication has been developed as an effective approach to improve the photocatalytic H2 evolution performance of graphitic carbon nitride (g-C3N4) based photocatalysts. In this work, we fabricated the Z-scheme In2O3 nanorod/C3N4 heterojunction and tailored the length of the In2O3 nanorod, by which the carriers' behavior of the In2O3/C3N4 heterojunctions could be subtly regulated. By employing finite difference time domain simulation and photoelectric characterization, we clarified the mechanism of the length-dependent regulation for photoelectric conversion efficiency. Due to the compromise between photoinduced exciton generation, dissociation, and migration as the nanorod length increased, the photoelectric conversion efficiency was maximized at an optimal length (53 nm) of the In2O3 nanorod, and the corresponding maximum H2 evolution rate of Z-scheme In2O3/C3N4 heterojunctions was 12.9 times higher than that of the pristine g-C3N4. This work provides a direct guideline for designing the optimal geometrical configuration of g-C3N4 based heterojunctions.

Bionic design and multi-objective optimization of thin-walled structures inspired by conchs

<abstract> <p>Thin-walled structures have been widely used in various parts of vehicle subsystems because of their high-efficiency impact energy absorption and lightweight characteristics. However, the impact deformation mode of conventional thin-walled structures is unstable and the energy absorption efficiency is low. Therefore, a series of novel bionic conch structures (BCS) are proposed to find a more excellent crashworthiness design in this study. First, the finite element simulation model of BCS verified by experiments is established. Then, the energy absorption characteristics of bionic conch structures, and conventional single-cell and multi-cell tubes under axial loading are compared by employing finite element simulation. The results show that the thin-walled structures inspired by conchs have a higher energy absorption efficiency than the other two structures with the same mass. In addition, the influence of main design parameters (wall thickness, inner and outer ring diameter, and the number of inner and outer panels) on the crashworthiness of BCS is studied through parameter design and factor significance analysis. Finally, the optimal geometric configuration is found by combining the approximation model and multi-objective particle swarm optimization, and the crashworthiness of BCS is further optimized. The bionic crashworthiness design and optimization framework proposed in this study can also provide a reference for other engineering protective structures.</p> </abstract>

Evaluation and comparison of thermal performance of latent heat storage units with shell-and-tube, rectangular, and cylindrical configurations

• Criteria are proposed to evaluate heat transfer, flow resistance, and irreversibility. • Shell-and-tube LHSU has the shortest phase change time and highest heat transfer rate. • Shell-and-tube LSHU achieves the highest j / f factor and the best thermal performance. • Cylindrical LHSU achieves the highest melting exergy efficiency of 81.5% • Shell-and-tube LHSU has the highest exergy efficiency of thermal store-release cycle. Latent heat storage plays a significant role in tackling the mismatch between energy supply and demand. Evaluation and comparison of the thermal performance of different shaped latent heat storage units (LHSU) are essential in the optimal design of LHSU. This study developed the numerical model of heat transfer and flow in shell-and-tube, rectangular, and cylindrical LHSU with the same PCM mass and heat transfer area. Two kinds of criteria, namely the j / f factor considering both heat transfer and flow resistance and the exergy coefficient evaluating irreversibility, are proposed to assess the performance of LHSU comprehensively. It shows that natural convection intensity in cylindrical LHSU is the highest, while the shell-and-tube LHSU exhibits the lowest phase change time and the highest heat transfer rate. The average j / f factor of shell-and-tube LHSU is 21.4% larger than that of rectangular LHSU and is twice as much as that of cylindrical LHSU. Therefore, the shell-and-tube LSHU achieves the best overall thermal performance. Moreover, cylindrical LHSU achieves the highest melting exergy efficiency of 81.5%, while shell-and-tube LHSU has the highest solidification exergy efficiency of 62.8%. Regarding the thermal storage and release cycle, the exergy efficiencies of shell-and-tube, rectangular, and cylindrical LHSU are 50.1%, 49.2%, and 48.5%, respectively. Therefore, shell-and-tube is the optimal shape to achieve the largest exergy efficiency of the thermal storage-release cycle. This study deepens the understanding of the thermal behavior of PCM packed in different shaped containers, obtains the optimal geometric configuration, and gives guidance to the optimal design of geometric parameters of the LHSU.

Optimal Measurement of Drone Swarm in RSS-Based Passive Localization With Region Constraints

Passive geolocation by multiple unmanned aerial vehicles (UAVs) covers a wide range of military and civilian applications including rescue, wild life tracking and electronic warfare. The sensor-target geometry is known to significantly affect the localization precision. The existing optimal sensor placement strategies mainly work on the cases without any constraints on the sensor locations. However, UAVs cannot fly/hover simply in arbitrary region due to realistic constraints, such as the geographical limitations, the security issues, and the max flying speed. In this paper, optimal geometrical configurations of UAVs in received signal strength (RSS)-based localization under region constraints are investigated. Employing the D-optimal criteria, i.e., maximizing the determinant of Fisher information matrix (FIM), such optimal problem is formulated. Based on the rigorous algebra and geometrical derivations, optimal and also closed-form configurations of UAVs under different flying states are proposed. Finally, the effectiveness and practicality of the proposed configurations are demonstrated by simulation examples.

Strategies to minimize beam and sample vibration-induced instabilities at the microfocus MX XAIRA beamline at ALBA

The performance of microfocus beamlines, and ultimately the quality of the diffraction data, is very sensitive to vibrations affecting the optical elements and the sample stages and holder. We report here the strategies applied in the design of the microfocus MX XAIRA beamline at ALBA synchrotron to mitigate the effects of two relevant sources of vibrations: circulation of LN2 flow to evacuate the thermal load on the monochromator and cryocooling gas stream being blown on the sample. The internal shape and size of the two cooling pads that clamp the monochromator optics have been designed to minimize the turbulences in the liquid nitrogen flow while maximizing heat transfer. Computational Fluid Dynamics (CFD) simulations and some preliminary metrology tests are presented. Besides, in the end-station, the cryo-cooler is blowing typically a 5-10 L/min flow of nitrogen or helium gas at 100K on the sample, inducing vibrations in the micron range. The optimal geometrical configuration between the sample holder and the cryocooler has been assessed by means of CDF simulations and metrology tests.

Minimization of entropy generation in U-bend tube heat exchanger during flow boiling of R134a

The presence of a bend in a tube during two-phase flow boiling can improve heat transfer while also causing a pressure drop. The goal of this paper is to achieve an optimal geometry of the U-bend tube heat exchanger. The bend induces a high-pressure drop as well as increases heat transfer coefficient, striking a balance between pressure drop and heat transfer coefficient to obtain an optimal design can be achieved by minimizing entropy generation due to heat transfer and pressure drop. Hence, an entropy generation minimization during two-phase flow boiling of R134a was conducted using the constructal design method and the entropy generation techniques based on the second law of thermodynamics. The geometric optimization was subjected to the following constraints: the volume of the tube was constant with bending radius, and the tube's outer surface area was subjected to a uniform constant heat flux of 10 kW/m2. Geometric parameters such as total length Lt, internal diameter di and external diameter do of the tube were free to morph with respect to the degree of freedom until an optimal geometrical configuration was obtained at minimum entropy generation. The bend's curvature ratio was taken as a function of internal (hydraulic) diameter. The numerical computations were conducted with the mass fluxes from 100 to 500 kg/m2s and quality of 0.2 at the tube's inlet for downward-oriented flow. The results obtained were consistent with those found in the open literature. Furthermore, the optimal parameters of the tube heat exchanger were found to vary slightly as the minimum entropy generation rises with an increase in mass flux. The stability was achieved as minimum entropy generation increased which demonstrates the robustness of the optimized U-bend tube.

Numerical investigation to assess the output performance of concentrated solar parabolic dish system

In this study, a standalone solar parabolic dish Stirling system is mathematically modeled and simulated using MATLAB to investigate the effects of material design and opt-geometrical parameters on output performance of the system. The concentrator diameter, rim angle, dispersion angle, incidence angle, solar angle, receiver emissivity, receiver absorbance, receiver thermal conductivity, and concentrator reflectance are the major parameters considered for investigation. The effects of the aforementioned parameters have been rigorously observed on Geometrical Concentration Ratio (G.C.R), receiver temperature, receiver thermal loss, output power, and overall efficiency of the system. In addition, the optimized values of the studied parameters have also been identified to establish the optimal geometrical configuration of the system. The results revealed that the maximum output power and the overall efficiency of the system have been calculated at 45° rim angle, 0.4° dispersion angle, 0° incidence angle, and 0.3° solar angle. At these optimal angles, receiver thermal loss may be significantly minimized while maintaining the desired G.C.R. The results, for the purpose of validation, have also been compared with theoretical and experimental dataset from the contemporary literature and found in good agreement.

Synthesis, spectroscopic studies, and single‐crystal structures of two 3‐D supramolecular zinc(II) and nickel(II) complexes containing thiazole ring: Antimicrobial assays, time‐dependent density functional theory calculations, and Hirshfeld surface analysis

Two novel complexes [Zn(L)2·(NO3)2] (1) and [Ni(L)2·2H2O]·2CH3OH·(NO3)2 (2) (L = 2‐(2‐thiazolyl)‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide) were synthesized successfully and characterized by elemental analysis, as well as various spectroscopic techniques. Specifically, the photoluminescence behavior of complex 1 was explored in different solvents. The structural characterization of both complexes has been determined single‐crystal X‐ray diffraction. It revealed that the metals in 1 and 2 are chelated by two L ligands in centro‐symmetrically fashion and the complexes are counterbalanced by nitrate ions which act as coordinating species in 1, while two water molecules complete the Ni coordination sphere in 2. In the crystal structures, the adjacent molecules of complex 1 disclosed a ladder‐like 2‐D network and 3‐D supramolecular self‐assembly. Simultaneously, an infinite 1‐D chain, 2‐D layered skeleton, and even meter‐shaped 3‐D network of 2 was governed by molecular interactions (H–bonds, C–H⋯π). Most strikingly, the research of antibacterial activity proved that two complexes had good activity against two standard bacteria strains. To ascertain deeply the optimum geometric configurations and detect the frontier molecular orbital energy gaps, density functional theory (DFT) calculations were also investigated. Additionally, analyses of Hirshfeld surfaces (HS) and electrostatic potential (ESP) were also performed to quantify the presence of diverse noncovalent interactions.