Geometrical Parameters Research Articles

A wide-band, high-resolution semi-von Hamos spectrometer for K-shell multi-ionization atoms X-ray measurements

A wide-band, high-resolution vacuum semi-von Hamos spectrometer has been developed for analyzing the X-rays spectra of K-shell multi-ionization atoms. The spectrometer covers an energy dynamic range of 0.6 to 18 keV with a corresponding single exposure spectral bandwidth of 0.25–1.2 keV. This capability is achieved by the combination of different cylindrically bent crystals and an X-ray CCD detector mounted on a twistable bellows, allowing modulation of the Bragg angles from 27° to 47°. A detailed mathematical description is employed to understand the dependence of the geometrical parameters of the spectrometer on the imaging properties, energy spectrum bandwidth, resolving power, solid angle, and other relevant spectrometer characteristics. An energy calibration has been performed by using K X-rays generated by 10–30 keV electron beam interactions with solid KCl, CaF2 and Se targets. The spectrometer exhibits a resolving power better than 103, enabling the analysis of fine spectral structure of K X-ray transitions and the comparison of X-ray properties between pure elements and their compounds due to chemical effects. The spectrometer also finds applications in various fields requiring precise X-ray measurements, including synchrotron radiation experiments, tokamaks, laser plasma diagnostics and laboratory astrophysics.

Study of the sizing of a fecal sludge treatment station in the town of Kissidougou (Republic of Guinea)

The management of fecal sludge is a concern for cities in Guinea such as the city of Kissidougou. This study aims to evaluate the feasibility of setting up a fecal sludge treatment station at the Songbo public landfill, 3 km from the city center of Kissidougou. The methodology adopted for this study is based on: the choice and installation site of the treatment structure, the determination of the geometric parameters of the station, the identification of construction materials and the estimation of the cost of carrying out the the work. For this reason, the upstream hypotheses were defined and the analytical formulas were used. The emptying flow produced by the urban municipality is estimated at 176 m3/day of materials. The volumes of these works are: optional basin (1300 m3); anaerobic pond (384 m3) and maturation pond (1828 m3). The investment cost of building the station amounts to 25 301 546 000 GNF over a requested area of 2 hectares. However, before the establishment of these stations, the Guinean government, through state structures, should carry out preliminary actions to raise awareness among all stakeholders in the sector and regulate it in order to be able to perpetuate this study project.

Comparison of Cu3, Cu5, and Cu7 clusters as potential antioxidants: A theoretical quest.

Herein, we compare and contrast the dual roles of Cun clusters (n = 3, 5, and 7 atoms) in scavenging or generating RO• free radicals from ROH at the theoretical levels (where R = H, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, and phenyl). This investigation is performed in water media to mimic the actual environment in the biological system. In the presence of the Cun clusters, bond dissociation energy (BDE) of RO-H and R-OH is reduced. This is clear evidence for the increased possibility of both the RO-H and R-OH bonds breakage and scavenging of RO• radicals. The nature of anchoring bonds responsible for the interaction of Cun clusters with ROH and RO• are interpreted using the quantum theory of atoms in molecules (QTAIM) and the natural bond orbital (NBO) analysis. The DFT results indicate that the O•⋅⋅⋅•Cu bond is stronger and has more covalent character in RO•⋅⋅⋅•Cun radical complexes than in ROH⋅⋅⋅•Cun. Therefore, the interactions of Cun clusters with RO• radicals (antioxidant) are more pronounced than their interactions with ROH non-radicals (pro-oxidant). The GAMESS software package was utilized in this paper. The B3LYP and M06 functions with the 6-311 +  + G(d,p), and LANL2DZ/SDD basis sets was used to perform the important geometrical parameters of RO•⋅⋅⋅•Cun and ROH⋅⋅⋅•Cun, binding energy (Eb), and bond dissociation energy (BDE).

Free vibration analysis of functionally graded sandwich spherical shells with honeycomb core resting on Kerr foundation using the MITC4 element

ABSTRACT The main object of this paper is to further extend the MITC4 element to analyse the free vibration of FG sandwich spherical shells with a honeycomb core (so-called h-FGSS shells) resting on Kerr foundation (KF). The MITC4 originates from a three-dimensional continuum description degenerated to shell behaviour which can be applied to both thick and thin shells. The h-FGSS shell consists of an inner honeycomb core and two different FG skin layers. FSDT is used due to its simplicity and efficiency. The KF includes three parameters as upper springer stiffness ( k U ), upper springer stiffness ( k L ), and the shear layer stiffness ( k S ). The performance and accuracy of the present formulation are verified through comparative examples. Furthermore, the numerical and graphical results show a general picture of the influence of the input parameters on the free vibration of h-FGSS shells, especially the geometrical parameters of the honeycomb core.

Assessing the accuracy of TD-DFT excited-state geometries through optimal tuning with GW energy levels.

We study the accuracy of excited state (ES) geometries using optimally tuned LC-PBE functionals with tuning based on GW quasiparticle energies. We compare the results obtained with the PBE, PBE0, non-tuned, and tuned LC-PBE functionals with available high-level CC reference values as well as experimental data. First, we compare ES geometrical parameters obtained for three different types of systems: molecules composed of a few atoms, 4-(dimethylamino)benzonitrile (DMABN), and conjugated dyes. To this end, we used wave-function results as benchmarks. Next, we evaluate the accuracy of the theoretically simulated spectra as compared to the experimental ones for five large dyes. Our results show that, besides small compact molecules for which tuning LC-PBE does not allow obtaining geometries more accurate than those computed with standard functionals, tuned range-separated functionals are clearly to be favored, not only for ES geometries but also for 0-0 energies, band shapes, and intensities for absorption and emission spectra. In particular, the results indicate that GW-tuned LC-PBE functionals provide improved matching with experimental spectra as compared to conventionally tuned functionals. It is an open question whether TD-DFT with GW-tuned functionals can qualitatively mimic the actual many-body Bethe-Salpeter (BSE/GW) formalism for which analytic ionic gradients remain to be developed.

Axial compressive behavior of spiral stirrup-reinforced concrete-filled cold-formed steel built-up box stub columns

This paper aims to explore the enhancement effect of spiral stirrup on concrete-filled cold-formed steel built-up box (CF-CFB) columns. Herein, four specimens were designed and fabricated to explore the impact of the spiral stirrup and riveted form on the axial compression performance of CF-CFB columns. Then, the finite element model of spiral stirrup-reinforced concrete-filled cold-formed steel built-up box (RCF-CFB) stub columns was established, and a systemic parametric investigation was conducted to explore the impact of geometric and material parameters on the compression performance of RCF-CFB stub columns. Afterwards, the analysis included an assessment of contact stress and stress distribution was conducted to uncover the confining effect. The analysis results revealed that the failure mode of the RCF-CFB column was tube buckling and concrete crush, accompanied by the spliced tube separating at the buckling area. The built-in reinforcement could significantly improve the performance of the built-up column, while riveted forms of spliced steel tubes had little effect. Furthermore, the axial bearing capacity of the RCF-CFB column would increase with the enhancement in steel yield strength, concrete strength, tube thickness, and longitudinal bar diameter. Finally, a calculating method to predict the axial bearing capacity of the RCF-CFB column was proposed, and the applicability of the method was demonstrated by comparison with experimental and FE data.

Numerical modelling of flow field at shaft spillways with the marguerite-shaped inlets

By decreasing the entrained air flow discharge and improving the hydraulic characteristics of vertical shaft spillways, Marguerite-shaped inlets (MSIs) can mitigate the effects of swirling flow surrounding their inlet. The hydraulic and hydrodynamic characteristics of flow around MSIs under orifice flow regime were numerically investigated, applying different geometrical parameters. This inlet configuration can decrease the strength of swirling flow and increase the flow discharge through the shaft. The finite-volume method and the re-normalisation group k–ε turbulence model were employed to solve the governing equations of motion in a cylindrical coordinate system and a two-phase air–water flow on the water free-surface. Increasing the height and length of the blades of the MSIs was found to increase the area of the barriers against swirling flow, weaken the swirling flow strength, engender a more uniform flow and lower the water free-surface level. Extremely long or high blades, however, resulted in an intense collision of the flow with the spillway and increased the water free-surface level and the swirling flow strength at the MSI.

The semi-analytical model of capacitive imaging (CI) sensors based on the renormalization group method

Purpose This study aims to design and validate a theoretical model for capacitive imaging (CI) sensors that incorporates the interelectrode shielding and surrounding shielding electrodes. Through experimental verification, the effectiveness of the theoretical model in evaluating CI sensors equipped with shielding electrodes has been demonstrated. Design/methodology/approach The study begins by incorporating the interelectrode shielding and surrounding shielding electrodes of CI sensors into the theoretical model. A method for deriving the semianalytical model is proposed, using the renormalization group method and physical model. Based on random geometric parameters of CI sensors, capacitance values are calculated using both simulation models and theoretical models. Three different types of CI sensors with varying geometric parameters are designed and manufactured for experimental testing. Findings The study’s results indicate that the errors of the semianalytical model for the CI sensor are predominantly below 5%, with all errors falling below 10%. This suggests that the semianalytical model, derived using the renormalization group method, effectively evaluates CI sensors equipped with shielding electrodes. The experimental results demonstrate the efficacy of the theoretical model in accurately predicting the capacitance values of the CI sensors. Originality/value The theoretical model of CI sensors is described by incorporating the interelectrode shielding and surrounding shielding electrodes into the model. This comprehensive approach allows for a more accurate evaluation of the detecting capability of CI sensors, as well as optimization of their performance.

Influence of microtextured parameters of dry gas sealing rings on tribological performance

Purpose This study aims to research the influence mechanism of microtextured geometric parameters of dry gas seal end face on the tribological behavior under dry frictional conditions. Design/methodology/approach The microtexture was processed using laser processing, while the diamond-like carbon (DLC) film was applied through magnetron sputtering; the experimental platform of friction vibration was established, the frictional and vibrational properties of different geometric parameters were tested; the data signals of vibrational acceleration and frictional torque were collected and processed using data acquisition instrument. The entropy characteristic parameters of 3D vibrational acceleration were extracted based on wavelet packet decomposition method. The end-face topography was measured with ST400 three-dimensional noncontact surface topography instrument. Findings The geometry of pits plays a key role in influencing friction performance; the permutation entropy and fuzzy entropy of the vibration acceleration signal changed with variations in microtextured parameters. A textured surface with appropriately size parameters can trap debris, enhance the dynamic pressure effect, reduce impact between the friction interfaces and improve the frictional vibrational performance. In this research, microtextured surface with Φ150 µm-10% and Φ200 µm-5% can effectively reduce friction and vibration between the end faces of a dry gas seal. Originality/value DLC film improves the hardness of seal ring end face, and microtexture improves the dynamic effect; the tribological behavior monitoring can be realized by analyzing the characteristics of vibration acceleration sensitive parameter with friction state. The findings will provide a basis for further research in the field of tribology and the microtexture optimization of dry gas seal ring end face. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0389/

Description of ”active domain” descriptor for catalysis center: N‐doped MoS 2  catalysts as an example

The development of descriptors to establish catalyst structure‐activity relationships is significant for the construction of efficient catalysts. In this work, we introduce the descriptor of "active domain" (φ) to describe the catalytic centers in N‐doped MoS2 with active edge perimeter and charge overlap ratio. The value of φ is quantified by the active edge perimeter related active site exposure ratio and charge overlap ratio corresponded product adsorption/desorption. The value of φ for rectangular‐like N‐MoS2, hexagonal‐like N‐MoS2, triangular‐like N‐MoS2 and quaternary‐like N‐MoS2 are 29.70, 22.17, 10.86, and 1, respectively. Therefore, the rectangular‐like N‐MoS2 active domains exhibit better catalytic activity than the other active domains. This descriptor based on catalyst geometric and electronic parameters contributes to design catalyst structures, predicts catalytic activity and investigates reaction mechanisms.

Structural Detection and Stability Monitoring of Deep Strata on a Slope Using High-Density Resistivity Method and FBG Strain Sensors

Under the influence of a variety of unfavorable factors, slope instability may occur, so the stability of the slope needs to be analyzed. In this paper, combined with the geological investigation data, the slope engineering geological profiles are derived based on 2D inversion maps of the high-density resistivity (HDR) method to obtain the overburden layer thickness. Then, a finite element model is established based on the mechanical and geometric parameters of the slope to analyze the displacement and deformation characteristics and obtain information about the potential sliding surface. The above analysis results are combined to determine the effective monitoring field and deploy (Fiber Bragg Grating) FBG strain detection piles for deep strain monitoring. The analysis showed that the shape and location of the potential sliding surface of the slope from the numerical simulation are consistent with those delineated by the HDR profile. The monitoring results show the rock and soil on the north side of the slope are soft and have poor stability, which is consistent with the HDR method detection results. Adopting the HDR method to identify the slope’s overall geological structure combined with FBG strain detection piles to obtain the deep deformation provided an effective monitoring technique for slope stability assessment.

Multiple Fano resonances by MIM waveguide coupling whispering gallery mode resonator and application in Refractive index sensing

Abstract In this study, a baffled metal – insulator – metal (MIM) waveguide coupled with a whispering gallery mode resonator (WGMR) is proposed. This structure could excite quadruple Fano resonances. The asymmetric Fano resonance transmittance spectrum and the electric field at the resonance peak were numerically simulated using the finite difference time domain method. The obtained data were fitted using the multimode interference coupled mode theory. The number of Fano resonance peaks was tuned by the outer radius of the WGMR. With other geometric parameters unchanged, the number of Fano resonance peaks increased with increasing outer radius of the WGMR. When the ring width was fixed, the structure could excite multiple Fano resonances within a certain outer radius range. This structure was used for refractive index sensing and its sensitivity and figure of merit (FOM) were 3004 nm/RIU and 3.14× 104 in a gas environment, respectively. Therefore, the proposed structure can excite multiple Fano resonances and achieve a high sensitivity and FOM, providing a theoretical basis for micro and nano applications.

Dissociation Constant of Di‐ and Tri‐Basic Solvents Based on Piperazine and Its Derivatives for Post‐Combustion CO2 Capture

AbstractAmine solvents remain popular in the industries for post combustion carbon dioxide (CO2) capture. Dissociation constant of basic amine solvents plays significant role to influence the CO2 absorption. It is thus important to study the dissociation of new amine solvents for assessing their viability for CO2 capture. In the present work, potentiometric titration method is employed to determine the dissociation constants of dibasic (e. g., Piperazine (PZ), 1‐methyl piperazine (1‐MPZ) and tribasic amines (1‐(2‐aminoethyl‐piperazine) (AEPZ) which could be promising for formulating blended solvent system towards enhancing the rate of CO2 absorption. The estimated dissociation constants for the PZ and 1‐MPZ while match well with reported results, the dissociation constants for AEPZ has been determined newly here within the temperature range 298—318 K. In addition, the structural geometric parameters and Natural Bond Order (NBO) calculations of the amine solvents are performed based on Density Functional Theory (DFT). The NBO calculations predict charge distribution on the nitrogen and other elements, and envisage its effect on the pKa values of the amines. Further, potential energy surface (PES) scanning calculations are performed for AEPZ to explain it's ring inversion which is responsible for obtaining a single pKa value in experimental studies.

A statistical shape analysis for the assessment of the main geometrical features of the distal femoral medullary canal

Statistical Shape Models (SSMs) are widely used in orthopedics to extract the main shape features from bone regions (e.g., femur). This study aims to develop an SSM of the femoral medullary canal, investigate its anatomical variability, and assess variations depending on canal length. The canals were isolated from 72 CT femur scans, through a threshold-based segmentation. A region of interest (ROI) was selected; sixteen segments were extracted from the ROI, ranging from 25% of the full length down to the most distal segment. An SSM was developed to identify the main modes of variation for each segment. The number of Principal Components (PCs) needed to explain at least 90% of the shape variance were three/four based on the length of the canal segment. The study examined the relationship between the identified PCs and geometric parameters like length, radius of curvature, ellipticity, mean diameter, and conicity, reporting range and percentage variation of these parameters for each segment. The SSMs provide insights into the anatomical variability of the femoral canal, emphasizing the importance of considering different segments to capture shape variations at various canal length. These findings can contribute for the design of personalized orthopedic implants involving the distal femur.

A ML strategy for the identification of optimal LPT design region and related blade shape

This work presents a machine-learning (ML) strategy for the identification of the design region that guarantees minimum losses for Low Pressure Turbine (LPT) blades, allowing the definition of the optimal blade shape. The data-driven procedure is twofold. Firstly, an advanced loss-correlation model (M1) that describes the LPT efficiency as a function of the main flow and geometrical parameters, also accounting for unsteady effects, has been trained from a numerical database. Then, a second model (M2) has been tuned to interpret the corresponding blade geometries. Proper Orthogonal Decomposition (POD) has been applied to formally decompose the blade shape into modes and coefficients. The modes provide basis functions, while the coefficients give the weights that, depending on the combination of the design parameters, define the blade shape. Gaussian Process (GP) and Cross-Validation techniques have been used for tuning both M1 and M2. Once properly tuned, the overall procedure provides the loss-correlation model (M1) for the identification of the design region that is expected to minimize losses, and the geometrical model (M2) for a quick definition of the corresponding optimal blade shape. The procedure can be extended to other engineering applications where own efficiency and geometrical data are available.

Effect of bending deformation on the electronic and optical properties of O atoms adsorbed by Be3N2.

In this paper, the optimum coverage of 4.44% and the optimum adsorption sites were determined for the Be3N2 adsorption system of O atoms at different coverages based on density functional theory. The electronic and optical properties of the model were investigated by applying bending deformation to the model at these coverage and adsorption sites. Adsorption of O atoms disrupts the geometrical symmetry of Be3N2, resulting in orbital rehybridization and lowering its band gap. Bending deformation causes the band gap of the adsorbed O atom structure of Be3N2 to first increase and then decrease, resulting in the modulation of its band gap. With increasing bending deformation, the adsorbed system is redshifts, and the degree of redshift increases with increasing bending deformation. All calculations in this paper were performed using the first-principles-based CASTEP module of Materials Studio (MS). The generalized gradient approximation (GGA) plane-wave pseudopotential method and the Perdew-Burke-Ernzerhof (PBE) Perdew et al. Phys Rev Lett 77:3865, 1996 generalized functional were used in the geometry optimization and calculation process to calculate the exchange-correlation potential between electrons. The effect of coverage on the electronic and optical properties of the Be3N2-adsorbed O atom system was investigated by adsorbing different numbers of O atoms on a monolayer of Be3N2. The Be3N2 protocell contains two N atoms and three Be atoms with a space community of P6/MMM (No.191). The original cell was expanded 3 times along the direction of the base vectors a and b in the Be3N2 plane to create a 3 × 3 × 1 monolayer Be3N2 supercell system. A vacuum layer of 15Å is set in the direction of the crystal plane of the vertical monolayer Be3N2 supercell to eliminate interactions between adjacent layers. In the overall energy convergence test of the Be3N2 supercell, the plane wave truncation energy was set to 500eV, and the energy difference between the calculations given in the literature Reyes-Serrato et al. J Phys Chem Solids 59:743-6, 1998 using 550eV was less than 0.01eV, verifying the reliability of the data at a truncation energy of 500eV. The Monkhorst-Pack special k-point sampling method Monkhorst et al. Phys Rev B 13:5188, 1976 was used in the structural calculations, and the grid was set to 3 × 3 × 1. The geometric optimization parameters are set as follows: the self-consistent field iteration convergence criterion is 2.0 × 10-6eV, and the iterative accuracy convergence value is not less than 1.0 × 10-5eV/atom for the total force of each atom and less than 0.03eV/Å for all atomic forces. In addition the high-symmetry k-point path is taken as Γ(0,0,0) → M(0,0.5,0) → K(- 1/3,2/3,0) → Γ(0,0,0) Chen et al, AIP Adv 8:105105, 2018.

Natural frequencies and stability for Z-shaped fluid-conveying pipes with constrained-layer damping – Semi-analytic modeling with experimental validation

As the common fluid-conveying component, pipe structures are susceptible to excessive vibration due to internal fluid and external excitation. Constrained-layer damping (CLD) is commonly applied to suppress structural vibrations. However, effective modeling and vibration suppression analysis for Z-shaped fluid-conveying pipes are lacking to explore novel dynamic behaviors. This paper presents a dynamic model for analyzing the three-dimensional vibration of Z-shaped fluid-conveying pipes treated by partial CLD based on the semi-analytical method. Utilizing Timoshenko beam theory and calculating the centrifugal, Coriolis, and inertial force of fluids, the energy of straight and curved fluid-conveying pipes treated by CLD is derived. Based on the Lagrangian energy function, the equation of motion is obtained by using the Rayleigh-Ritz method. The improved artificial spring set is deployed to model the interaction of pipe sections and the non-uniform constraint distribution of clamps. Modal parameters are obtained by solving characteristic equations. The proposed method is verified by comparisons with references and modal experiment results. Frequency parameters, damping effects, and stability are analyzed under various fluid, geometric, and CLD parameters. In conclusion, a novel dynamic model is provided for analyzing the vibration and stability of the Z-shaped fluid-conveying pipe treated by CLD, which lays a foundation for vibration suppression research of fluid-conveying pipe systems.

Simultaneous identification of geometric parameters and structural stiffness of serial robots composing flexible links

It has been a formidable challenge to accurately predict the pose of serial robots composing flexible links due to the difficulties in simultaneously considering geometric errors and link flexibility. This paper presents an approach for simultaneously identifying kinematics and stiffness parameters in the flexible serial robot. A compliance equivalent method is employed to model the flexibility in the joints and links nonlinearly. Based on this, the kinetostatics model of those serial robots can be established analytically. By approximating the force-deflection characteristics of the flexible links, a unified error model containing both geometric and compliance parameters is derived. Moreover, an adaptive total-least-square method is proposed for the identification considering constraints on the compliance coefficient. To verify the effectiveness of the proposed method, simulations on a single flexible link, a serial robot, and experiments on a 3-DOF planar serial manipulator are carried out. The results show that the residual errors of the manipulator can be significantly reduced by identifying the kinematics and stiffness parameters using the proposed approach.

Nanometer refractive index sensor based on water droplet cavity structure with rectangular short rod

In this paper, a novel nano sensor structure is proposed, which consists of a metal-insulator-metal waveguide (MIM) with rectangular baffles and a water droplet cavity with rectangular stubs (WDCRS). The WDCRS structure optimizes the sensitivity of a single water droplet cavity and makes the transmission curve clearer and smoother. The transmission characteristics of WDCRS structure were simulated using finite element method (FEM). The transmission characteristics of the exported structure were analyzed in detail. In addition, the influence of structural geometric parameters on sensing performance was also studied, and it was found that the size of the water droplet cavity is a key factor in improving sensitivity. When applied to a refractive index sensor, the structure achieves a sensitivity of up to 2,300 nm/RIU with a corresponding figure of merit (FOM) of 60.5. These works provide some ideas for the design of high-performance nanostructures and multiple Fano resonance excitation structures.

Structural design, interfacial behavior and mechanical properties of bimetallic nacre-like structures by laser powder-bed fusion

The nacre-like (NL) structure exhibits unique performance in preventing the catastrophic crack growth and improving the strengthening/toughening of the overall structure. In this study, the In718/316LSS bimetallic NL structures were first fabricated by a powder laying-absorption multiple-material additive manufacturing technology based on laser powder-bed fusion, and the stress release mechanism was revealed. The NL structures with optimal geometric parameters was obtained by calculation and simulation: the hard-phase inclination angle of 15 °, the hard-phase volume fraction of 70%, and the lamellar length-width ratio of 2. Due to the remelting effect, the same-layer bimetallic interfaces in NL structures showed strong metallurgical bonding with significantly grain refinement. The interlocking NL structure exhibited superior mechanical properties of 751.82 MPa in tensile strength and 25.14% in elongation, compared with the base alloys and the non-interlocking NL structure. Moreover, abnormal variation of work hardening rate in NL structures attributed to the stress concentration and release behavior, caused by the multi-cracks initiation and cracks deflection during deformation of the interlocking structure. By the stress concentration-release effect, the NL structure not only achieved the strengthening and toughening, but also improved the crack tolerance to avoid the sudden fracture failure.