Dimensional Analysis Research Articles

Micromechanical Characterization of AlCu Films for MEMS Using Instrumented Indentation Method.

The micromechanical properties (i.e., hardness, elastic modulus, and stress-strain curve) of AlCu films were determined by an instrumented indentation test in this work. For three AlCu films with different thicknesses (i.e., 1 µm, 1.5 µm, and 2 µm), the same critical ratio (hmax/t) of 0.15 and relative indentation depth range of 0.15-0.5 existed, within which the elastic modulus (i.e., 59 GPa) and nanoindentation hardness (i.e., 0.75 GPa, 0.64 GPa and 0.63 GPa for 1 µm, 1.5 µm and 2 µm films) without pile-up and substrate influence can be determined. The yield strength (i.e., 0.754 GPa, 0.549 GPa and 0.471 GPa for 1 µm, 1.5 µm and 2 µm films) and hardening exponent (i.e., 0.073, 0.131 and 0.150 for 1 µm, 1.5 µm and 2 µm films) of Al-(4 wt.%)Cu films for MEMS were successfully reported for the first time using a nanoindentation reverse method. In dimensional analysis, the ideal representative strain εr was determined to be 0.038. The errors of residual depth hr between the simulations and the nanoindentation experiments was less than 5% when the stress-strain curve obtained by the nanoindentation reverse method was used for simulation.

The political economy of agroecological transitions: key analytical dimensions

ABSTRACT There is a growing global interest in agroecology, yet agroecological transitions remain fraught with challenges. These include the need to reconfigure the productive and reproductive agrarian relations of unsustainable food systems and to rethink how we work with ecosystems. Using a political economy approach, we propose five key interrelated dimensions for analyzing agroecological transitions: (i) social metabolism; (ii) labor dynamics; (iii) markets and resources; (iv) social organization; and (iv) policies and politics. While these dimensions are often analyzed separately and to varying degrees, we argue that together they contribute to a comprehensive analysis of the political economy of agroecological transitions.

Thermal conductivity measurements of liquid ethane and ethane + propane binary mixtures

Based on the transient hot-wire apparatus, the thermal conductivity of ethane was measured in the temperature range of 146–247 K and pressure < 14 MPa in the liquid phase. The thermal conductivity of ethane + propane binary mixture was measured in the temperature range of 156–288 K and pressure < 25 MPa in the liquid phase. The mole fractions of ethane in binary systems are 0.198, 0.525, and 0.736. The deviation between experimental results and REFPROP calculation falls within 3 % of ethane and mixture. Subsequently, the previous established thermal conductivity model, derived from dimensional analysis, was employed to predict the thermal conductivity of n-alkanes mixture. The mixture critical parameters were obtained first by the mixing rules, and the thermal conductivity of the mixture were calculated. Comparisons were made between the experimental data of ethane and the previously constructed n-alkane model, resulting in an average absolute relative deviation (AARD) of 4.42 %. Similarly, the experimental data of the ethane + propane mixture was compared with the mixture prediction model proposed in this study, yielding an AARD of 1.92 %. The relative deviation between experimental data and model calculations demonstrates good consistency.

Comprehensive Scoping Review on Body Image Perceptions and Influences in Children and Adolescents.

Conducting a scoping review helps identify research gaps and opportunities, avoid duplication, guide the selection of appropriate methodologies, and base studies on existing evidence. The aim of this study was to map the literature on body image in children and adolescents (0 to 19 years). The present study follows the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA). The search was conducted in the following databases: PubMed, Web of Science, Scopus, SPORTDiscus, LILACS, SciELO, PsycINFO, CINAHL, and the Cochrane Library. A total of 3257 articles were found, of which 2147 were duplicates, resulting in 1110 articles. Of these, 41 met the inclusion criteria. The results were divided into analytical dimensions, including measurement instruments, programs and interventions, social media, sociodemographic aspects, physical activity, personality and cognitive thinking, and studies with specific populations. The results highlight that peer influence, physical activity, media, and the school environment play crucial roles in shaping young people's body image; factors such as sex, age, and socioeconomic context emerge as important variables in understanding body perceptions, and educational interventions and health promotion programs have been shown to be effective in preventing and reducing body dissatisfaction, underscoring the need for multifactorial and collaborative approaches.

Resting-state functional connectivity in anxiety disorders: a multicenter fMRI study.

Anxiety disorders (AD) are associated with altered connectivity in large-scale intrinsic brain networks. It remains uncertain how much these signatures overlap across different phenotypes due to a lack of well-powered cross-disorder comparisons. We used resting-state functional magnetic resonance imaging (rsfMRI) to investigate differences in functional connectivity (FC) in a cross-disorder sample of AD patients and healthy controls (HC). Before treatment, 439 patients from two German multicenter clinical trials at eight different sites fulfilling a primary diagnosis of panic disorder and/or agoraphobia (PD/AG, N = 154), social anxiety disorder (SAD, N = 95), or specific phobia (SP, N = 190) and 105 HC underwent an 8 min rsfMRI assessment. We performed categorical and dimensional regions of interest (ROI)-to-ROI analyses focusing on connectivity between regions of the defensive system and prefrontal regulation areas. AD patients showed increased connectivity between the insula and the thalamus compared to controls. This was mainly driven by PD/AG patients who showed increased (insula/hippocampus/amygdala-thalamus) and decreased (dorsomedial prefrontal cortex/periaqueductal gray-anterior cingulate cortex) positive connectivity between subcortical and cortical areas. In contrast, SAD patients showed decreased negative connectivity exclusively in cortical areas (insula-orbitofrontal cortex), whereas no differences were found in SP patients. State anxiety associated with the scanner environment did not explain the FC between these regions. Only PD/AG patients showed pronounced connectivity changes along a widespread subcortical-cortical network, including the midbrain. Dimensional analyses yielded no significant results. The results highlighting categorical differences between ADs at a systems neuroscience level are discussed within the context of personalized neuroscience-informed treatments. PROTECT-AD's registration at NIMH Protocol Registration System: 01EE1402A and German Register of Clinical Studies: DRKS00008743. SpiderVR's registration at ClinicalTrials.gov: NCT03208400.

Experimental study into the sedimentation process of solids of different origin

Sedimentation refers to the first stage of wastewater treatment from mechanical impurities. Its rate depends on the density and particle size of impurities, as well as the density and viscosity of dispersion medium. In industrial sedimentation tanks, particle settling can occur in laminar, transient or turbulent modes. Aim. To establish the criterion equations and their coefficients for sedimentation processes of sand, glass and polyamide granules. Sedimentation of sand particles of 0.001– 0.003 m, spherical glass particles with the diameter of 0.0025–0.004 m and polyamide granules with the volume-surface mean diameter of 0.0022–0.003 m was carried out in a measured glass cylinder filled with distilled water. Each solid particle was measured, then, it came into contact with the water surface by means of tweezers, and released, starting to settle to the bottom of the cylinder under the action of gravity. A stopwatch was used to time the particle passaging between the marks of the measured cylinder. Calculations were performed using dimensional analysis. According to the test results, the dependences of the Reynolds number on the Archimedes number were established for the sedimentation of sand particles and polyamide granules in the transient mode, while spherical glass particles in the turbulent mode. In addition, the criterion equations of the solid particles sedimentation in the liquid were derived. The coefficients for these equations were experimentally determined. The equations and coefficients obtained in the study can be used in the design of settling tanks for mechanical treatment of wastewater to remove sand, glass and polymer particles.

Field-Testing Multiple-Choice Questions With AI Examinees: English Grammar Items

Field-testing is an essential yet often resource-intensive step in the development of high-quality educational assessments. I introduce an innovative method for field-testing newly written exam items by substituting human examinees with artificially intelligent (AI) examinees. The proposed approach is demonstrated using 466 four-option multiple-choice English grammar questions. Pre-trained transformer language models are fine-tuned based on the 2-parameter logistic (2PL) item response model to respond like human test-takers. Each AI examinee is associated with a latent ability θ, and the item text is used to predict response selection probabilities for each of the four response options. For the best modeling approach identified, the overall correlation between the true and predicted 2PL correct response probabilities was .82 (bias = 0.00, root mean squared error = 0.18). The study results were promising, showing that item response data generated from AI can be used to calculate item proportion correct, item discrimination, conduct item calibration with anchors, distractor analysis, dimensionality analysis, and latent trait scoring. However, the proposed approach did not achieve the level of accuracy obtainable with human examinee response data. If further refined, potential resource savings in transitioning from human to AI field-testing could be enormous. AI could shorten the field-testing timeline, prevent examinees from seeing low-quality field-test items in real exams, shorten test lengths, eliminate test security, item exposure, and sample size concerns, reduce overall cost, and help expand the item bank. Example Python code from this study is available on Github: https://github.com/hotakamaeda/ai_field_testing1

Dimensional and experimental analysis for predicting the material removal rate in AJM

ABSTRACT One of the upcoming methods for machining brittle and heat-sensitive materials is abrasive jet machining (AJM) where the process of erosion aids in material removal. This is accomplished by the impact of abrasives transported using a stream of gas having high velocity onto the workpiece. The erosion mechanism is a complicated process, which involves cutting, fracturing and micro structural transformation, thereby causing the evaluation of response parameter like rate of material removed (MRR) an arduous task. In this paper, an effort has been made to develop a semi-empirical model for predicting MRR in hole machining of soda-lime glass by utilising dimensional analysis (DA) technique. In this model, the compressive stress developed during the impact of loading and velocity of the particle are considered as a function of work material, selected abrasive material properties and process parameters. The validation of the evolved model was carried out with experiments that involve process parameters such as operating pressure, stand of distance (SOD) and abrasive particle size. From the analysis, it’s found that the predicted MRR model created by the dimensional analysis method gave an average error of 11.8%. thereby giving a reasonably compatible value with experimental results.

Dimensional Error Analysis of Cortical Screw during Threading of Magnesium AZ31

Developments in manufacturing to achieve large productivity and high-quality products in the modern era have necessitated the need of using suitable methods. Taguchi or robust design method has been implemented to optimise a process in a single response. This experiment aims to analyse the cutting parameters of geometrical errors of threads. Machining trials were conducted on the diameter of the workpiece (10, 14 and 18 mm), depth of cut (0.23, 0.3067 and 0.46 mm) and spindle speed (212, 318 and 424 rpm). Three responses, namely, pitch, height threads and angle thread error, were investigated. The external thread selected is metric M1,5 with three levels of three factors. Results show that spindle speed was the most significant factor that affected pitch error and height thread error. Depth of cut and diameter of the workpiece significantly affected thread angle error. The optimal condition to produce low thread angle error included machining at level 1 diameter of the tool, level 3 depth of cut of and level 3 spindle speed.

Effects of new nonlinear curvature models and non-local elasticity on buckling investigation of FG tapered nano-beams locating on elastic foundations

New nonlinear curvature models are proposed to show their effects on the compressive critical buckling load on functionally graded (FG) tapered nano-beams locating on elastic foundations in the presence of non-local elasticity. Fourth and fifth orders finite difference methods (bvp4c and bvp5c) are applied on the governing differential equation which is a highly non-linear, due to curvature and has variable coefficients, due to properties. Dimensional analyses have been applied on the governing system together with the problem conditions to produce their dimensionless forms. For different considered parameters, the critical buckling load is computed using the eigenvalue theorem. The effects of nonlinear curvature, variable Young modulus, variable moment inertia and foundation parameters are studied and displayed in tables and figures. The stability and convergence of the present solution are tested using more than one strategy as: comparison with available results, comparison between bvp4c and bvp5c with different mesh intervals and tolerances of truncation errors. These comparisons show that, the new curvature model affects the critical buckling with different ratios depending on variability of properties and foundation parameters. The new results show that the nonlinear curvature model reduces the critical buckling load in comparison with the classical linear model, which, leads to decreasing in factor of safety in design of structures. The new results show that the design of structures will be influenced with the new reduction of the compressive critical buckling load, since it may affect the factor of safety in design of structures. The new results can lead, generally, to more reduction of critical buckling load for large or small input parameters and it will affect other critical values such that frequencies. The introduced Tables and Figures of the present problem with comparisons of previously exact, analytical and numerical works establish the higher accuracy and stability of current findings using bvp4c or bvp5c with preferable of the later. This study is related to some practical applications such as aeronautical and structural engineering.

Dynamic failures at the metal-glass interface under impact loading

To investigate dynamic fracture behavior in the metal, three metal spheres (e.g., steel sphere, high purity tungsten sphere, and high purity lead sphere) are accelerated by the gas gun devices to impact glass spheres under the critical speed range (i.e., from 70 m/s to 210 m/s). The velocity interferometer system for any reflector (VISAR) devices are employed to measure the particle velocities at the back surface of glass sphere, and high-speed photographs are utilized to capture the failure process at the metal-glass interface. Due to the asynchronous evolutions of stress fields and strain fields in the violent failure process, the results illustrate quite different failure mechanisms from those by the Split Hopkinson Pressure Bar (SHPB) impacting. Fragmentations of the glass sphere are caused mainly by the radial cracks and the lateral cracks around the metal-glass interface and the edges of the sphere with increasing impact velocity. Dynamic failures in the three metal impactors exhibit different modes, e.g., tensile fracture in the steel impactor, shear fracture in the tungsten impactor, and compressed yielding in the lead impactor. The transferring of strain energy releasing is introduced to describe the failure behavior at the metal-glass interface, and a relaxation-diffusion equation of strain energy releasing is then established based on the experimental results and the numeric results by the discrete element method (DEM). The evolutions of failures at the metal-glass interface are discussed. Further investigation is conducted to describe the dynamic fractures in tungsten impactors and steel impactors based on the dimensional analyses, and the quantitative expressions of these strain rate dependent fracture strains and crack width in the metal impactors are obtained. The results are helpful for the profound understanding of the dynamic fracture in the metal structures and the dynamic fragmentations in the brittle material when subjected to impact loading.

Investigation of Surge Phenomena in a Centrifugal Compressor by 3D-1D Coupling Approach

Abstract Critical instability, such as surge phenomena, can occur at low flow rates for a compressor system, leading to flow rate fluctuations and potential damage. To study this, traditional numerical analysis requires a comprehensive approach encompassing the compressor and its piping system. This demands extensive computational resources and time due to the complexity of capturing internal flow during surge, including separation and vortex generation. To overcome these limitations, this research proposes a computational strategy combining 3D and 1D analysis for enhanced efficiency and reduced computational demands, which employs 1D analysis for more straightforward flow regions like piping and 3D analysis for the more complex compressor section. This approach is facilitated using AMESim for 1D and STAR-CCM+ for 3D simulations, enabling seamless integration and data exchange between different dimensional analyses. The method improves computational efficiency and reasonably approximates surge phenomena compared to experimental data. The 3D and 1D coupled analysis closely aligns with experimental data, providing a viable and more effective alternative method for surge analysis in compressor systems. This methodology promises to streamline the study of compressor surge phenomena, providing a practical tool for engineers and researchers.

Development of empirical models for the modular limit of trapezoidal and triangular throat flumes

One of the essential challenges of flow measurement using the flume structure is whether the flow is free or submerged. Therefore, determining the free-submerged flow boundary is a vital topic. This study experimentally investigates the modular limit/threshold submergence of two kinds of flumes: trapezoidal throat flume (TraTF) and triangular throat flume (TriTF). To this end, the general form of empirical models of the flumes' modular limit index was presented based on dimensional analysis and incomplete self-similarity theory. Then, a set of experimental data was collected. In the next step, empirical relationships were developed using non-linear multivariate regression. The experimental modeling was done in a channel that was 20 m long, 0.6 m wide, and 0.5 m high. A total of 271 tests were conducted, examining nine flumes with trapezoidal throats and four with triangular throats at various flow rates. The TraTF formula has been developed, with 98% of its predictions having an error of less than 10% and an average error of 3%. For the TriTF formula, 96% of its predictions have an error of less than 10%, and the average error is 3.6%.

Theory of similarity and ultrasonic testing

Application of similarity theory (dimensional analysis) to ultrasonic (UT) testing is discussed using as an illustration the example of concrete blocks. The concept of dimensional analysis makes it possible to represent a physical system via a minimal set of variables, the so-called π groups, which are the dimensionless quantities. These dimensionless parameters, characterizing the respective phenomenon, should have approximately equal values for the real object and for the model. Small concrete samples have been tested in the lab conditions using various UT probes and techniques. Two dimensionless criteria, valid and similar for the real field case and for the laboratory samples, have been introduced: total attenuations of UT waves and ratios of void size to the UT wavelength. To get total attenuations in the field conditions for thick concrete block, similar to the total attenuations measured in lab experiments on small samples, one should apply the low-frequency UT waves 60-100kHz. However, these UT waves will be able to reliably detect only the large inhomogeneities (e.g. voids), whose size is about half of the used UT wave, i.e. inhomogeneities with dimensions larger than 20-40mm.

Urban displacement and placemaking in public space for wellbeing: a systematic review of global literature

Cities and towns are critical geographies of refuge for a globally unprecedented number of forcibly displaced people. Yet urban processes also expose these groups and the local urban poor to recurrent displacements. While such experiences are shared, studies often treat these populations as distinct. Drawing on Yiftachel’s notion of displaceability, this paper systematically reviews and synthesizes a global literature on diversely displaced people’s placemaking in urban public space. Observing a significant analytical gap regarding cities of the so-called global South, the paper identifies a heuristic, and key analytical dimensions shaping divergent access and uses of public space by variously displaced populations. These concern: temporal patterns; powerful meta-narratives of people and place; and complex multi-scalar and multi-actor configurations of regulatory regimes governing public space. Simultaneously, acquisition and deployment of urban knowledge and a practice of (in)visibility enable differentially displaced populations’ everyday claims to public space for wellbeing.

Comprehensive characterization of the irradiation effects of glassy carbon

Carbon materials have become increasingly diverse, finding applications in high-temperature and high-radiation environments. Glassy carbon, an allotrope known for its exceptional chemical inertness and desirable mechanical properties. However, understanding neutron irradiation effects in glassy carbon has proven challenging, primarily because of its unique nanopore structure. This study presents a highly detailed microstructural characterization investigation of neutron-induced changes in glassy carbon, revealing how changes in nanopore structure and crystallinity impact the irradiation-induced shrinkage. Aberration-corrected scanning transmission electron microscopy (STEM) reveals pore closure that leads to material densification in the irradiated samples. Dimensional analysis combined with comparison to historical data suggest significant length shrinkage to occur. Neutron and in situ electron irradiation experiments suggest that glassy carbon transforms into so-called carbon onions, supporting the concept of shrinkage saturation. Investigating irradiation temperature effects using STEM, electron energy loss spectroscopy, x-ray diffraction, and Raman spectroscopy revealed partial amorphization at 210 °C–230 °C and preserved order in glassy carbon at 860 °C, coinciding with pore closure. Thermal property measurements were also conducted to assess the effects of densification and other changes in the atomic structure of glassy carbon. The results of this study have broad implications in the deployment of glassy carbon to nuclear environments, based around the observed changes in the thermal properties, and demonstrates the operational window for the onset of densification.

Integrating dimensional and scaling analyses with functional modelling and graphs: An approach to comprehend mass transfer in welding

Integrating dimensional and scaling analyses with functional modelling and graphs: An approach to comprehend mass transfer in welding

Dimensional and Hierarchical Assessment of American Kennel Club Breeds and Behavioral Trait Descriptions

The AKC functions as the largest and most influential dog breed registry and breed standard information source in the United States. AKC breed standards describe the breed’s overall appearance and behavior. Despite their popularity, the AKC behavioral descriptions and the traits used to quantify them have largely remained unexplored. In this study, we used eleven behavioral breed standard traits for 286 breeds collected for the official AKC source. Dog size and appearance were also evaluated. We employed pairwise correlation and factor analysis to define behavioral trait constructs and hierarchical clustering methods to evaluate the similarity of breed profiles. These methods revealed that although AKC data exhibit various individual correlations concurrent with known canine behavior, many breeds present behavioral trait constructs that do not align with the narratives presented in their standard and may be lacking crucial factors in dog behavior, as suggested by breed group clustering. Our dimensional analysis revealed three constructs, which we labeled as “Social Engagement”, “Pet Demands”, and “Vigilance”, that are very important and relevant to pet ownership. These results emphasize the importance of standardized observations when quantifying behavior and provide an overarching context regarding the strengths and weaknesses of these descriptions, allowing readers to better understand and predict their pet’s behavior.

The stage-discharge relationship of a sharp-crested triangular weir pierced by square orifices

In this paper, the stage-discharge equation of a sharp-crested triangular weir pierced by square orifices is deduced applying both the classical approach of the discharge coefficient Cd and the Π- Theorem of dimensional analysis and the self-similarity theory. At first, using the experimental data by Zeinivand et al. (2024), the applicability of the expression of the discharge coefficient proposed by these authors was verified. Then, applying the dimensional analysis, a new stage-discharge relationship was deduced and calibrated using the available dataset. This theoretical equation is characterized by errors in the discharge estimate that are less than or equal to ±20 % for 98.9 % of cases and ≤ ±10 % for 87.8 % of cases, and the root mean square error is equal to 0.00071 m3 s−1. In conclusion, the stage-discharge relationship deduced by dimensional analysis is characterized by an improvement in the performances in the discharge estimate and also has the advantage of working without the need of estimating the discharge coefficient.

Flow measurement mechanism and hydraulic characteristics analysis of the airfoil weir-orifice facility in a rectangular channel

ABSTRACT Experimental studies and numerical simulations are conducted on the airfoil weir-orifice facilities to find a flow measurement and control device with a stable combined outflow form and good hydraulic performance. The orifice height under the weir is changed by adjusting the chord length and rotation angle of the weir. This paper uses three airfoil weir-orifice facilities for comparative study. The facilities have three flow forms under different rotation angles and flow conditions. Orifice discharge in combined outflow form is related to weir crest height but not upstream water depth. Flow formulas for three discharge forms are derived using dimensional analysis and incomplete self-similarity theory. The results show that the relative error of the formula is within ±6.34%. The Froude number is less than 0.4 under all working conditions; the critical submerged range is between 0.7 and 0.95; and under the premise of the unified weir crest height, the head loss decreases with the increased orifice height. The hydraulic jump location analysis yields the airfoil weir-orifice facility under the combined outflow as a submerged orifice outflow, and the hydraulic jump energy cancelation efficiency under the same flow condition is consistent with the upstream water depth change trend.