Laboratory Experiments Research Articles

Magnesium geochemistry of authigenic carbonate at marine cold seep

Cold seeps, featured by their extremely methane-rich sedimentary environments, play a significant role in the geological history and are common in marine sediments across the seafloor. Primary dolomite, possibly mediated by microorganisms, can be widely discovered in methane-rich environments. Hence, cold seeps may provide new insights into the ‘dolomite problem’, which has confused geologists for decades. Magnesium isotope geochemistry of seep carbonates contributes to the understanding of the dolomite formation mechanism in marine environments. In this paper, magnesium geochemical characteristics of carbonates in modern sediments are summarized, along with rare researches on magnesium isotopes of seep carbonates. Methane vigorously interacts with sulfate by anaerobic oxidation of methane at cold seeps, producing vast amounts of dissolved sulfide which can significantly promote dolomitization of seep carbonates. Compared with temperature, alkalinity, mineralogy, etc., the competition between rapid carbonate precipitation rates and aqueous ligands may be the main factor of the magnesium fractionation at cold seeps, which is controlled by the kinetic effect. The range of magnesium isotopes of seep carbonates is narrow (from -3.46‰ to -2.36‰), and an upper limit of magnesium content seems to exist. This characteristic may be a good indicator for identifying dolomitization related to anaerobic oxidation of methane. Whereas, mechanisms of magnesium isotope fractionation and dolomitization at cold seeps remain unclear, necessitating more natural samples tested, stimulated calculation and laboratory experiment.

Study on the response mechanisms and evolution prediction of groundwater microbial-toxicological indicators.

This study aims to investigate the response mechanisms of groundwater microbial-toxicological indicators, specifically total bacteria count (TBC) and total coliform count (TCC), to water quality indicators and environmental conditions. Using data from a water source in the western plateau of China, a predictive model focusing on TBC and TCC was developed. An orthogonal experimental design was employed to manipulate environmental conditions such as temperature, pH, and porosity, facilitating laboratory experiments. These experiments measured pH, chemical oxygen demand (COD), oxidation-reduction potential (ORP), TBC, and TCC at varying depths and environmental conditions. Principal component analysis elucidated the mechanisms by which water quality indicators and environmental conditions affect groundwater microbial-toxicological indicators. A prediction model for these indicators in plateau regions was established based on a backpropagation neural network (BP-NN), using TBC and TCC as target variables and the newly extracted principal components as influencing factors. The results demonstrate that environmental conditions and water quality indicators primarily influence the evolution of groundwater microbial-toxicological indicators by altering the ionic charge quantities, redox conditions, and temperature of the groundwater. The predictive model for groundwater microbial-toxicological indicators shows trends consistent with experimental outcomes, with an average relative error of less than 15%, meeting engineering requirements. PRACTITIONER POINTS: The values of total bacteria count (TBC) and total coliform count (TCC) under different conditions were obtained by column experiments. The influence mechanism of environmental conditions and groundwater indicators on TBC and TCC was elaborated by principal component analysis. TBC and TCC prediction models were established through the investigation of water sources in a plateau area and laboratory experiments.

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.

Case specific: Addressing co-digestion of wastewater sludge, cheese whey and cow manure: Kinetic modeling

The study investigated the methane production efficiency in a semi-continuous laboratory experiment with periodic feeding of wastewater sludge (WWS) as primary substrate and addition of whey (CW) and cow manure (CM). The short-term behavior of a real-scale anaerobic digester with WWS and the methane production improvements with different feeding mixtures of WWS, CW and CM were addressed. Gradual addition of CW to WWS (WWS:CW:CM = 70:20:0 to 70:55:0) increased the average daily methane production to 48.6 mL CH4/g COD/day and prevented reactor failure, but high VOA/TIC values showed that the reactors were conditionally stable evolution at an OLR of 8 g COD/L/day. Reactors that were additionally supplemented with CM (WWS:CW:CM = 70:55:10) achieved at least 12.3 % more methane than the reactors supplemented with WWS and CW alone. The highest methane production and process evolution in the reactors were achieved at OLRs between 7.5 and 8.7 g COD/L per day. After day 50, the addition of double the amount of CW further increased the methane production and VOA/TIC ratios. In this case, the OLR increased from 6.3 to 9.3 g COD/L/day. The concentration of propionic and acetic acid in all reactors increased above the recommended values and caused inhibition and instability. A strong positive Pearson correlation was found between the trace elements (Fe, Cu, Zn, Mn) detected by XRF. TE contributed to methane production, but to a lesser extent than TIC and NH4+-N. The simplified model successfully predicted methane production under a periodic feeding regime.

On the analytical soliton approximations to damping forced Zakharov-Kuznetsov equation arising in dissipative nonthermal magnetized plasma

Abstract This paper aims to analyse the nonlinear characteristics of ion-acoustic solitary waves (IASWs) in a plasma system that is collisional and homogeneous in nature. The system under consideration comprises positive ions, negative ions, and nonthermal electrons and is influenced by an ambient magnetic field. To analyse the system, we utilize the reductive perturbation technique (RPT) and obtain the damped forced Zakharov-Kuznetsov (DFZK) equation. The DFZK equation provides a solitary wave solution when an external periodic force is present. Through numerical analysis of DFZK, we have observed that different parameters, e.g., the nonthermal parameters (r,q), the direction cosine, the temperature ratio of a positive ion to an electron, the temperature ratio of a negative ion to an electron, the density ratio of a negative ion to a positive ion source strength, and the source frequency, affect the phase velocity and the structures of IASWs significantly. This finding could help clarify the plasmas observed in the D- and F-regions of Earth's ionosphere, as well as in laboratory experiments where pair ions and nonthermal electrons are key characteristics.

The corporate legality game a lab experiment on the impact of policies, frames and information

The corporate legality game a lab experiment on the impact of policies, frames and information

Investigation of smoothed particle hydrodynamics (SPH) method for modeling of two-phase flow through porous medium: application for drainage and imbibition processes

The drainage and imbibition processes are critical mechanisms in petroleum engineering. These processes in a porous medium are controlled by surface forces and pressure gradients. The study of these processes in the pore scale by common simulators always has limitations in multiphase flow modeling. Also, obtaining relative permeability curves through laboratory analysis requires expensive equipment. Additionally, these laboratory experiments are quite expensive and may introduce significant uncertainties. For this purpose, this study investigated the creation of relative permeability curves and their effect on oil production. Initially, single-phase fluid and two-phase droplet flow within a fracture with both soft and rough surfaces were utilized to validate the formulation of the Smoothed Particle Hydrodynamics (SPH) method. Then, by using three randomly constructed porous medium models, the imbibition and drainage processes have been studied. Finally, sensitivity study has been carried out on critical parameters related to fluid flow dynamics in the porous environment, including pressure changes, wettability, and heterogeneity in drainage and imbibition processes. The simulation results were consistent with current theories; therefore, it is reasonable to consider SPH to characterize the fluid flow dynamic during the drainage and imbibition processes. According to sensitivity studies, pressure gradient (residual saturation of displaced fluid is about 5.65% and 8.44%) and heterogeneity (the residual saturation of the displaced fluid was 4.04% and 2.98%) have the largest impact on flow modeling in both drainage and imbibition processes and wettability (the residual saturation became 36.62% and 5.12%) has significant effect on the drainage process through porous medium. In general, fluid flow dynamic studies can be performed using the SPH method to model fluid flow in simple and complex porous medium under various flow conditions. The SPH method can also be used as an applicable tool to investigate the hydrocarbon fluids flow within larger geometries in the future.

Recent replenishment of aliphatic organics on Ceres from a large subsurface reservoir.

Ceres hosts notable aliphatic-organic concentrations, ranging from approximately 5 to >30 weight % in specific surface areas. The origins and persistence of these organics are under debate due to the intense aliphatic organic signature and radiation levels in Ceres' orbit, which would typically lead to their destruction, hindering detection. To investigate this, we conducted laboratory experiments to replicate how the signature of the organic-rich regions would degrade due to radiation. Our findings indicate a fast degradation rate, implying the exposure of buried organics within the past few million years. This degradation rate, coupled with observed quantities, implies that the aliphatics must be present in substantial quantities within the shallow subsurface. Our estimates suggest an initial aliphatic abundance 2 to 30 times greater than currently observed, surpassing significantly the levels found in carbonaceous chondrites, indicating either a significant concentration or remarkable purity.

Comparative Analysis of Foundation Systems in Expansive Soil: A Three-Dimensional Model Approach to Moisture Diffusion and Volume Changes

AbstractThis study compares the performance of various foundation systems in expansive soils, such as mats, granular anchor piles, and concrete piles. Expansive soils experience volumetric changes due to moisture fluctuations, which can lead to structural damage. Abaqus software, in conjunction with the SCV approach, is used to analyze soil-foundation interactions. A custom subroutine enhances simulation accuracy by incorporating empirical data on unsaturated clay behavior, matric suction, and variations in effective stress. The method’s accuracy is validated by comparing simulation results to field and laboratory experiments. The findings indicate that increasing the applied load on mats decreases overall heave but increases the differential heave. Additionally, higher soil permeability dereases the differential heave of mats. Granular anchor piles outperform concrete piles by more than 50% in highly expansive soils, suggesting a preference for these foundations. This study provides insights into the behavior of expansive soils, which will assist engineers in designing resilient foundation systems for structures.

Enhancing Concrete Properties with Banana Stem Juice Additive: A Study on Workability and Compressive Strength

Additives are integral components of modern concrete mixing materials. This study aimed to evaluate the workability and compressive strength of concrete incorporating banana stem juice as a natural additive (BSJA). A laboratory experiment was conducted to assess the impact of BSJA on concrete properties. Concrete mixtures with a ratio of 1:2:4 were prepared both with and without BSJA. A total of 36 cube specimens were created with varying percentages of banana stem juice, and their compressive strengths were measured. The results indicated that the inclusion of banana stem juice affected the concrete properties. On the 21st day, the compressive strength of the concrete without BSJA was 27.67 N/mm², compared to 29.67 N/mm² for 5% BSJA, 16.33 N/mm² for 10% BSJA, and 8.00 N/mm² for 15% BSJA. The slump values recorded were 15 mm for 0% BSJA, 20 mm for 5% BSJA, 45 mm for 10% BSJA, and 65 mm for 15% BSJA. The average compressive strengths of concrete specimens with 5% BSJA at 14 days (23.3 N/mm²) and 21 days (29.2 N/mm²) were higher than those of specimens without BSJA. Over the 14 and 21-day periods, specimens with BSJA consistently showed higher compressive strengths compared to those without. These results suggest that 5% BSJA enhances the compressive strength properties of concrete.

The Similarity of Quasi-geostrophic Vortices Against the Background of Large-Scale Barotropic Currents

The paper proposes a theory of similarity of quasi-geostrophic vortices against the background of large-scale flows. This information is useful when planning laboratory and numerical experiments to study mesoscale and submesoscale vortex dynamics of vortices interacting with currents. Special attention is paid to the study of geometric similarity of phenomena. It is revealed that the complete set of dimensionless similarity numbers of baroclinic vortices includes four dimensionless parameters: the dimensionless intensity of the vortex, the geometric similarity of the background flow (the ratio of relative vorticity to the deformation coefficient of the background flow), the coefficient of horizontal elongation of the vortex core and the coefficient of vertical oblateness of the vortex core coinciding with the Burger number. To describe the similarity of barotropic vortices against the background of barotropic flows, the number of necessary dimensionless parameters is reduced by one number — the coefficient of vertical oblateness of the vortex core is eliminated from consideration. When studying axisymmetric vortices or vortex structures close to axisymmetric, another geometric parameter of the vortex is eliminated from consideration — the coefficient of horizontal elongation of the vortex core. As a result, the maximum possible set of similarity parameters includes four dimensionless numbers, and the minimum is two.

Effect of noninertial acceleration on heat transfer by Rayleigh–Bénard magnetoconvection: Exploring nonlinear dynamics

AbstractBuoyancy‐driven Rayleigh–Bénard convection in the presence of a magnetic field, rotation, and temperature‐dependent viscosity has applications in the field of crystal growth, space laboratory experiments, and atmospheric convection. It also has potential applications in heat transfer and magnetohydrodynamics, which can occur in planetary and stellar interiors. The present work aims to study the combined effect of magnetic fields and rotation on the onset of Rayleigh–Bénard convection in temperature‐dependent viscosity Newtonian liquids with internal heat sources/sinks. Both linear and weak nonlinear stability analyses of convection are performed in the problem. The minimal representation of the Fourier series for the stream function and the magnetic potential allows us to derive the analytical expression for the thermal Rayleigh number () and the generalized Lorenz model. In linear theory, the critical Rayleigh number and the wave number are tabulated for different values of the Chandrasekhar number (), the Taylor number (), and the thermorheological parameter (), and the onset of stability is analyzed. It is found that the instability manifests at when for stress‐free and isothermal boundaries. In nonlinear theory, the generalized Lorenz model obtained is not amenable to analytical treatment; therefore, the classical fourth‐order Runge–Kutta method is applied to solve the Lorenz model. It is found that the internal Rayleigh number, the thermorheological parameter, and the Taylor number influence the onset of convection and heat transfer coefficient. It is also demonstrated that the joint increase in rotational force and magnetic field strength stabilizes the system strongly, thereby reducing heat transfer. However, increasing the heat source and the variable viscosity parameter have antagonistic influences.

Analysis of rock-breaking mechanisms of high-voltage pulsed electric electrode bits

High-voltage pulsed electric rock-breaking technology is an innovative, green, and efficient method with substantial potential in the field of rock fragmentation. The efficiency of this technology is primarily determined by the design of the electrode bit. To investigate the impact of electrode bit design on rock fragmentation, this study developed a three-dimensional electro-rock breaking model based on the coupling of multiple fields: current field, electrostatic field, breakdown field, heat transfer field, and solid mechanics field. Using this comprehensive three-dimensional model, we conducted dynamic electrical breakdown simulations of granite, incorporating five different electrode bit structures and six degrees of rock heterogeneity. The simulation results elucidate the effects of pulsed peak voltage, granite heterogeneity H , and electrode bit structure on the efficiency of high-voltage pulsed electric rock breaking. To validate the simulation results, laboratory experiments on electro-rock breaking were performed. The experimental findings indicate that the conical electrode bit exhibited the highest rock-breaking efficiency, while the pentagonal prism-shaped electrode bit showed the poorest performance. The tip of prismatic electrodes generates a tip discharge effect; for the triangular prism, this effect often results in irregular rock fragmentation, which is detrimental to drilling efficiency. These results highlight the significant influence of electrode shape on rocks’ electrical breakdown and fragmentation. This study provides valuable insights into the engineering application of high-voltage pulsed electric rock-breaking technology.

Settling of two rigidly connected spheres

Laboratory experiments and particle-resolved simulations are employed to investigate the settling dynamics of a pair of rigidly connected spherical particles of unequal size. They yield a detailed picture of the transient evolution and the terminal values of the aggregate's orientation angle and its settling and drift velocities as functions of the aspect ratio and the Galileo number $Ga$ , which denotes the ratio of buoyancy and viscous forces acting on the aggregate. At low to moderate values of $Ga$ , the aggregate's orientation and velocity converge to their terminal values monotonically, whereas for higher $Ga$ -values the aggregate tends to undergo a more complex motion. If the aggregate assumes an asymmetric terminal orientation, it displays a non-zero terminal drift velocity. For diameter ratios much larger than one and small $Ga$ , the terminal orientation of the aggregate becomes approximately vertical, whereas when $Ga$ is sufficiently large for flow separation to occur, the aggregate orients itself such that the smaller sphere is located at the separation line. Empirical scaling laws are obtained for the terminal settling velocity and orientation angle as functions of the aspect ratio and $Ga$ for diameter ratios from 1 to 4 and particle-to-fluid density ratios from 1.3 to 5. An analysis of the accompanying flow field shows the formation of vortical structures exhibiting complex topologies in the aggregate's wake, and indicates the formation of a horizontal pressure gradient across the larger sphere, which represents the main reason for the emergence of the drift velocity.

Investigation of human interaction with an augmented remote operating system for scaling in mining applications

Thanks to the advent of telepresence applications, we can remotely take control and operate industrial machinery. Teleoperation removes operators from hazardous workplaces such as mining and plays an essential role in the safety of workers. In addition, augmented telepresence can introduce information that helps the user understand the remote scene. However, remote operation presents challenges since the information received is more limited than what could be perceived by being physically present, such as accurately judging depth. This study investigates how well operators interact with an augmented remote operation scaling system (AROSS) in a mining context when different computer-generated visual interfaces are provided. The system can achieve five visual interfaces: Disocclusion Augmentation view using selective content removal, Novel Perspective view generation, Lidar view, Right (Original) view, and Left (Original) view. We performed two experiments in a mine-like laboratory to analyze human interaction with the designed prototype by applying a mixed research methodology that used questionnaires, interviews, and observations. This mixed methodology consisted of quality of experience methods to discover the users’ requirements from a technological standpoint and user experience methods (i.e., user-centric approaches). We investigated 10 and 11 users’ interactions in two experimental studies. The first experiment focused on identifying small patterns (e.g., cracks in the mine wall), and the second focused on depth and three-dimensional understanding. We considered the first experiment a feasibility test to understand how to conduct the second experiment. Therefore, we designed the second test to assess the technical readiness of AROSS from the users’ perspective. The overall conclusion yields a comprehensive understanding of users’ perceptions and experiences. The quality of experience results favored Left and Right (Original) views for remote control, indicating a preference among remote operators using natural (Original) views due to their facilitation of environmental comprehension. User experience analysis revealed the reason why other views were less favored and what their potential benefits are. Specifically, Novel Perspective and Lidar views were found helpful for depth perception, and Disocclusion Augmentation view functionality could be enhanced if robot arm position tracking is enabled. These insights inform design recommendations, emphasizing the value of incorporating Disocclusion Augmentation and Novel Perspective views and suggesting improvements to enhance system usability.

Effect of Biochar on Composting of Cow Manure and Kitchen Waste

Composting is a common method for managing organic waste and creating nutrient-rich soil amendments. Recently, biochar, a carbon-rich material from biomass pyrolysis, has been noted for potentially improving composting. This study examines the impact of adding biochar to compost made from cow manure and kitchen waste through a controlled lab experiment. The treatments were labeled as CMX (cow manure), KWX (kitchen waste), and CMKWX (both) with X being the percentage of CM, KW, and CMKW minus that of biochar in the mixture. Key parameters such as temperature (T), pH, and electric conductivity (EC) were tracked during the composting processes, and the final composts were analyzed for total nitrogen (N), available nitrogen (AN), total phosphorus (TP), available phosphorus (AP), total potassium (TK), organic carbon (OC), calcium (Ca2+), magnesium (Mg2+), and organic matter (OM). The results showed that adding less than 10% biochar influenced composting positively. Specifically, 5% biochar amendment led to higher thermophilic temperatures (45–57 °C) and stable pH levels (6.3–8.7) compared to controls. However, biochar did not significantly enhance EC, which peaked at 1.78 dS/m in both the control and 5% biochar treatments. Nutrient analysis revealed that biochar increased Ca2+ (13.62 meq/g) and Mg2+ (5.73 meq/g) retention in CM composts (CM85 and CM100). The highest OM content was 16.84% in CM90, while the lowest was 3.81% in CM95. Higher OM negatively affected TN, with CM treatments having more OM and KW treatments having more TN. TP and TK were higher in control treatments without biochar. This study highlights the benefits of integrating biochar with organic waste for enhancing compost nutrient profiles and soil fertility. It was observed that the more diverse the compost feedstock, i.e., CMKW, the higher the nutrient content for treatments containing less than 10% biochar.

The Impact of Using Doodling in The Educational Environment On the Degree of Learning of Educational Material

Introduction. This article is devoted to the study of doodling as a process of unconscious drawing by students during active thinking activity under experimental conditions. The relevance of the study is conditioned by the expressed public demand for the development and implementation of new methods and technologies in the modern educational process. The novelty of the study lies in the relatively low level of study of this phenomenon to date and the contradictory nature of the available practical data on its effectiveness. Thus, the presented work will help to supplement the still unstable scientific understanding of such a widespread phenomenon as “drawing on the margins”. Objective. To compare the degree of learning of educational material in students when using doodling and the classical method of memorization on the basis of historical text. Materials and Methods. Forty-eight psychology students at SFU, aged 17 to 22 years, 43 of them women and 5 men, were chosen as subjects. The subjects were divided into control and experimental groups, each of which was read a historical text. Then, 30‒40 minutes after the end of the experiment, each group completed the author’s questionnaire of 10 open-ended questions on the listened material. The results of each subject were evaluated by the degree of the completeness of answers and summarized for each group to then find the average value for each and compare. Results. The experimental group, which used doodling techniques, showed noticeably worse learning and reproduction results than the control group. Discussion. The results obtained are partially reflected in the work of other authors who were unable to reproduce the data, showing the advantages of doodling in memorizing information. It can be assumed that the results of the experiment were influenced by the relatively small size of the stimulus material and the morning time of the experiment: the subjects did not have time to tire, so they did not have a natural need for additional methods of attention retention. Perhaps, for this reason, a natural experiment could show better results on the use of doodling than a laboratory experiment. It is alsopossible that this method is only useful for people with certain characteristics. Further experimental studies with other conditions of doodling playback in different educational environments, subjects, and stimulus material are needed to clarify the phenomenon.

Uji Efektivitas Daya Hambat Ekstrak dan Perasan Lidah Buaya (Aloe barbadensis Miller) pada Bakteri Staphylococcus Aureus dengan Metode Difusi

Aloe vera is a plant that is rich in minerals, vitamins, and antibacterial properties. A study to analyze the antibacterial effectiveness of aloe vera in inhibiting the growth of Staphylococcus aureus bacteria isolated from acne pus. This study was an experimental laboratory study using the disc diffusion method, located at the Bacteriology Laboratory, Department of Medical Laboratory Technology, Poltekkes Kemenkes Surabaya, from February to May 2024. There were 6 sample treatments with 4 replications, 4 treatments of extract and juice concentration variations, namely concentrations of 70%, 80%, 90%, 100%, positive control using penicillin antibiotics, and negative control using clean distilled water. The results of this study show that at aloe vera extract concentrations of 70%, 80%, 90%, and 100%, the average diameter of the inhibition zone was 9 mm, 10 mm, 11 mm, and 12 mm, respectively, while in aloe vera juice, these concentrations did not form an inhibition zone. So it was concluded that aloe vera extract is more effective than aloe vera juice, the most successful test material to slow the growth of Staphylococcus aureus bacteria in this study was aloe vera extract with a concentration of 100%. This study also conducted qualitative phytochemical testing on aloe vera extract which has antibacterial compounds, namely saponins, tannins, flavonoids, and terpenoids. The results of the study on the effectiveness of the inhibitory power of aloe vera extract and juice against Staphylococcus aureus bacteria using the disc diffusion method were analyzed using quantitative descriptive and presented in tabulation form in the form of the diameter of the inhibition zone formed.

How to mathematically model a drill-string: lumped or continuous models?

This work compares the efficacy of lumped and continuous models in simulating drill-string dynamics. We aim to critically explore the inadequacy of lumped models and challenge their perpetuated use in the literature. Lumped models represent the drill-string with a pre-determined number of discrete masses, sometimes as few as one or two. This inherently restricts their ability to capture the distributed nature of drill-strings, compromising their accuracy. In this paper, these limitations are made evident by comparing simulations of lumped models with simulations of continuous models that increase in complexity. First, predictions of the axial behaviour obtained with two models, one lumped and another continuous, are analysed. Second, simulations involving a 3-D fully coupled continuous model are evaluated. The simulations demonstrate the inaccuracy of lumped models. Also, they refute the frequent assumption of representing the bottom hole assembly (BHA) as a single lumped mass. Beyond these results, theoretical arguments based on fundamental wave-reflection phenomena are employed to further support the inadequacy of lumped formulations for this purpose. Third, this paper also discusses the prevalent strategy of validating lumped models through comparisons with laboratory experiments. This approach suffers from being a makeshift validation, as similitude principles are often violated in laboratory setups, resulting in a practice that may have helped perpetuate lumped models in the literature. Consequently, using lumped models for general drill-string dynamics prediction is not appropriate. Recognising their limitations and exploring alternative approaches, such as continuous models, is crucial for accurate drill-string dynamics prediction.

Complementary Instrumental Techniques Applied to Pain Relieving Tablets in an Undergraduate Laboratory Experiment

Complementary Instrumental Techniques Applied to Pain Relieving Tablets in an Undergraduate Laboratory Experiment