Experimental Tests Research Articles

Elucidating the Impact of Polyol Functional Moieties on Exothermic Poly(urethane-urea) Polymerization: A Thermo-Kinetic Simulation Approach

The pursuit of sustainable polyurethane (PU) product development necessitates a profound understanding of precursor materials. Particularly, polyol plays a crucial role, since PU properties are heavily influenced by the type of polyol employed during production. While traditional PUs are solely derived from hydroxyl functionalized polyols, the emergence of amine-hydroxyl hybrid polyols has garnered significant attention due to their potential for enhancing PU product properties. These hybrid polyols are characterized by the presence of both amine and hydroxyl functional groups. However, characterizing these polyols remains a daunting challenge due to the lack of established experimental testing standards for properties, such as fractional hydroxyl and amine moieties and thermo-kinetic parameters for amine reactions with isocyanates. Additionally, characterization methods demand extensive time and resources and pose risks to health and the environment. To bridge these gaps, this study employed computational simulation via MATLAB to determine the moieties’ fractions and thermo-kinetic parameters for hybrid polyols. The computational method integrated energy balance and reaction kinetics analysis for various polyols to elucidate the influence of functional moieties on the thermo-kinetic behavior of PU formations. Validation of the simulated results was conducted by comparing their experimental and simulated prepolymer and foam temperature profiles, highlighting the direct influence of fractional moieties on PU formations. The comparisons revealed an average relative error of less than 5%, indicating the accuracy and credibility of the simulation. Thus, this study represents a pivotal opportunity for advancing knowledge and driving sustainable developments in bio-based polyol characterization for PU production streamlining and formulation optimization.

Structure prediction of protein-ligand complexes from sequence information with Umol

Protein-ligand docking is an established tool in drug discovery and development to narrow down potential therapeutics for experimental testing. However, a high-quality protein structure is required and often the protein is treated as fully or partially rigid. Here we develop an AI system that can predict the fully flexible all-atom structure of protein-ligand complexes directly from sequence information. We find that classical docking methods are still superior, but depend upon having crystal structures of the target protein. In addition to predicting flexible all-atom structures, predicted confidence metrics (plDDT) can be used to select accurate predictions as well as to distinguish between strong and weak binders. The advances presented here suggest that the goal of AI-based drug discovery is one step closer, but there is still a way to go to grasp the complexity of protein-ligand interactions fully. Umol is available at: https://github.com/patrickbryant1/Umol.

Monitoring framework development for a network of multiple laboratory structures

The stadium structures have unique structural features increasing the significance of structural monitoring systems specifically designed for them. Aside from vibrations serviceability concerns and human-induced excitations, the development and propagation of structural damage under all possible atmospheric and seismic conditions need to be closely monitored for structural resiliency and integrity of the stadia. As such, Structural Health Monitoring (SHM) methods combined with effective data evaluation methodologies need to be deployed to monitor the structural performance of stadiums. Even though stadia monitoring has been performed at multiple locations in the world, a web based and real-time SHM network of stadia is not known to authors. As a preliminary study for the network implementation of stadia monitoring with acceleration measurements, the presented work focuses on the fundamental steps to accomplish this goal, with a collaborative research effort between Qatar University, the University of Central Florida, and University of Alberta. The authors performed analytical investigations and experimental testing on stadium-type structures built in laboratory environments for the development of the SHM framework. Specialized signal processing algorithms, sensing suites and approaches considering multi-scale monitoring were used on collected acceleration measurements. The novelty of the work presented in this manuscript are the following items which exist simultaneously in the developed SHM framework. The developed framework is a web-based monitoring application where structural damage is detected in real-time. The proposed methodology operates directly on raw acceleration signals and runs at a network level. With that, the damage detection, damage localization, and damage quantification tasks are performed simultaneously, while the feature extraction and classification stages are combined in one learning body.

Experimental and analytical study on eccentrically loaded Fiber concrete columns reinforced longitudinally with GFRP bars

In this paper, experiments were carried out to analyze the behavior of the square columns reinforced longitudinally by GFRP bars along with different ratios of hooked end fibers under eccentric compressive loading. Eight short square columns with a cross-section dimension of 150x150mm and a height of 1200 mm, were fabricated to conduct the experimental program. A 150 mm enlargement in column-cross at both ends was considered to develop an eccentric axial load. The columns were tested under different load eccentricity ratios (0.26, 0.5, 1). Different tie spacings (50, 100, 120) mm. Different ratios of steel fibers 0 %, 0.5 %, and 1 % were incorporated into the concrete mix. It was observed that columns with steel fibers demonstrated good characteristics, including higher ultimate load, increased ultimate deflection, and enhanced ductility and toughness compared to the columns without steel fibers due to multiple cracking behaviors. The ductility of the columns reinforced with GFRP bars was enhanced by 46.8 %, and 68 % for steel fiber volume ratios of 0.5 % and 1 %, respectively. The energy absorption was increased by 42 % and 77 % for steel fibers ratios of 0.5 % and 1 %, respectively. When GFRP bars were used as longitudinal reinforcement, there was an improvement in the bond behavior between the concrete and the GFRP bars. All concrete columns reinforced by GFRP bars failed due to flexure-compression failure. There was no observed rupture of GFRP bars during the experimental test and the maximum strain did not reach 40 % of their ultimate strain capacity. Nonlinear Finite Element analysis was conducted to simulate the behavior of tested columns. The equations from previous studies and the codes were established to predict the nominal peak capacity of columns considering all parameters. In general, there was a reasonable level of agreement observed between the experimental data and the theoretical results determined for seventy-column specimens in the current study and from previous studies in the literature.

Theoretical and experimental study of a new antioxidant xanthone: Solvent and intramolecular hydrogen bond effects

Free radicals are harmful reactive species that cause various problems in the human body. Antioxidant compounds, such as xanthones found in natural products, can help prevent these effects. This study focuses on the antioxidant behavior of ravenelin (RVL) and ravenelin B (RVLB), a newly discovered xanthone in the Exserohilum rostratum fungus. Both experimental and in silico tests were conducted, comparing them to ascorbic acid, a standard antioxidant. The results showed that RVL has a lower bond dissociation energy (312 kJ/mol) than ascorbic acid (313 kJ/mol), indicating comparable antioxidant performance. This difference is mild but agrees with the experiment that indicates RVL efficiency is equivalent to ascorbic acid at low concentrations. RVLB, however, demands higher dissociation energy (323 kJ/mol) and consequently it has a lower antioxidative efficiency. Thus, antioxidant capacity is found as RVL>ascorbic acid>RVLB. From experimental assays, the RVL performance was confirmed through experimental tests at different solute concentrations. The study also examines the effects of solvents and intramolecular hydrogen bonds. Ravenelin molecules present three hydroxyl groups involved in intramolecular OH⋯O interactions. However, analysis based on the infrared spectra, as well as Bader's theory and non-covalent interactions done in water solvent showed that the two strongest H-bonds (≈−37 kJ/mol) better stabilize the molecular structure, but are not favorable to antioxidant reactions, indicating that hydrogen scavenging occurs at the less hydrogen-bonded hydroxyl group. The solvent also plays an active role first in facilitating hydrogen abstraction besides changing the hydrogen scavenging mechanism according to the environmental polarizability. Additionally, the antioxidant mechanism of ravenelin molecules changes from nonpolar to polar solvents, allowing for hydrogen abstraction.

Optimizing Individual HIV Testing and Counseling for Emerging Adult Sexual Minority Men (Aged 18 to 24) in Relationships: A Pilot Randomized Controlled Trial of Adjunct Communication Components.

The majority of new HIV infections in the US occur among sexual minority men (SMM) with older adolescent and emerging adult SMM at the highest risk. Those in relationships face unique HIV prevention challenges. Existing sexual HIV transmission risk interventions for male couples often encounter implementation challenges and engaging younger SMM early in relationships may be particularly difficult. This pilot randomized controlled trial evaluated the acceptibility and feasibility of We Test HIV testing - a behavioral health intervention tailored for younger SMM in realtionships - and generated preliminary estimates of effect size. The intervention comprises two adjunct moduls - video-based communication skills training as well as communication goal setting and planning - delivered in conjunction with routine HIV testing and counseling in individual or dyadic formats. A sample of 69 SMM aged 17 to 24 were recruited online. Following baseline assessment, youth were randomized to receive either the experimental, We Test, intervention or routine HIV testing (the control condition). Follow-up assessments were completed 3 and 6 months post-baseline. Results suggested the study was feasible and the individually delivered format was acceptible. We Test HIV testing was associated with significant improvements in communication skills. In addition, youth who remained in a relationship experienced an increase in communal coping to reduce HIV infection risk and relationship power. While groups did not differ with respect to condomless anal sex with casual partners, these psycho-social constructs (communication, communal coping with HIV prevention, and relationship power) may serve as mediators of intervention effects on sexual risk reduction in a larger study.

Hands-Free Haptic Navigation Devices for Actual Walking.

In this survey, we give an overview of hands-free haptic devices specifically designed for navigation guidance while walking. We present and discuss the devices by body part, namely devices for the arm, foot and leg, back, belly and shoulders, waist and finally the head. Although the majority of the experimental tests were successful in terms of reaching the target while being guided by the device, the experimental requirements were wide-ranging. The distances to be covered ranged from just a few meters to more than a kilometer, and while some of the devices worked autonomously, others required the experimenter to act as Wizard of Oz. To compare the usefulness and potential of these devices, we created a table in which we rated several relevant aspects such as autonomy, conspicuity and compactness. Major conclusions are that outdoor devices have the highest technology readiness level, because these allow autonomous navigation through GPS, and that the most compact devices still require the action of an experimenter. Unfortunately, none of the hands-free devices are at a level of readiness where they could be useful to people with visual impairments. The most important factor that should be improved is localization accuracy, which should be high and available at all times.

Enhancing sustainability in construction: experimental testing and finite element investigation of falsework ringlock joints

Enhancing sustainability in construction: experimental testing and finite element investigation of falsework ringlock joints

A practical leader–follower hybrid control scheme for wheeled mobile robots

This paper addresses the problem of tracking control of wheeled mobile robots in leader–follower formation. By applying the backstepping technique, a hybrid control scheme consisting of continuous control and intermittent control is proposed, and leader–follower formation tracking is achieved in the presence of model uncertainty and external disturbance. A relationship between the intermittent control width and control gain and the convergence of the position errors is obtained for the tracking accuracy estimation. As a special case, the concerned intermittent control can be converted to impulsive control with a sufficiently small control width, and tracking of the trajectory can be realized by directly driving the state variables of the follower at well-designed discrete instants. The main novelty of the proposed hybrid control scheme is to drive the tracking errors into a preset region via intermittent control (or impulsive control) signals and then achieve the tracking goal in the practical sense via continuous control signals. An example with the corresponding numerical simulations and experimental tests is given to illustrate the effectiveness of the proposed method.

Wear protection assessment of ultralow viscosity lubricants in high-power-density engines: A novel wear prediction algorithm

AbstractDurability and reliability have been studied for decades through intensive trial-error experimentation. However, there are numerous fields of application where the costs associated with this approach are not acceptable. In lubricated machines with severe dynamic loads, such as high-power-density engines, simulation tools offer clear advantages over intensive testing. Prototypes and multiple scenarios can be cost-effectively simulated to assess different lubricants and engine configurations. The work presented here details the study of wear based on a validated elastohydrodynamic (EHD) simulation model of the connecting rod journal bearing. This model accounts for elastic deformation through a connecting rod finite element model (FEM). In addition, multiple lubricant rheological and tribological dependences, determined by specific experimental tests, are applied in the model through their interaction with the simulation software. Correspondingly, a novel wear algorithm is proposed to predict wear depth over time evolution along a proposed wear cycle based on the typical working ranges of high-performance engines. A final assessment is presented to compare 4 different ultralow-viscosity lubricants in their protective performance under severe conditions. The results show the evolution of the wear load and wear depth over the wear cycle. This evaluation is key to describing a lubricant selection procedure for high-power-density engines.

Correlation between thermal and density properties of chestnuts: preliminary results of experimental non-destructive testing

This study presents the preliminary outcomes of a methodology for the physical and mechanical characterization of various chestnut elements in different states of preservation. Strategizing conservation and retrofit interventions for timber is necessary, and to do this, it is necessary to establish an estimation of physical (transmissivity, thermal conductivity, humidity level, etc.) and mechanical properties (density, compressive or bending strength, etc.). This essential information is typically associated with timber defects, but there are lack of correlations. The primary objective is to establish correlations between thermal and density properties with the aim of preserving original assets. The investigation delves into the relationship between timber density and thermal properties through experimental non-destructive testing (NDT). Two NDTs were employed with the aim of correlating: penetrometric testing and active thermography investigations. The parametric study on the excitation period yielded valuable insights into the temporal dynamics of heat transfer within the timber, underscoring the significance of selecting appropriate excitation periods to capture precise thermal properties. Tabular data on relative humidity for salified, dried, and new samples provided a quantitative backdrop to these observations, unveiling the nuanced effects of humidity on the timber’s thermal response. The results of this study are positioned to inform future conservation efforts by laying the groundwork for a comprehensive understanding of timber’s mechanical properties. Particularly, the challenge lies in accurately estimating density, where surface tests are often less reliable than in-depth ones. Therefore, it is crucial to seek validation through other NDT tests, such as thermographic analysis and visual inspection, and hygrometric tests recognizing their importance in enhancing the reliability of density assessments. This approach will contribute to the development of more discerning preservation strategies.

Experimental test and analysis of impact suppression for hydraulic-driven leg using a new MR damper with multi-channels

When hydraulic-legged robots move under high loads on irregular ground, they are vulnerable to ground impacts. Vibration affects the motion performance of the robot and damages its mechanical structure. This study aims to improve the properties of vibration absorption and impact resistance of hydraulic-legged robots. Because the traditional MR damper (MRD) has small output in finite volume, a novel MRD with a multistage flow channel (MFC-MRD) can output a large damping force designed. First, an MRD prototype was designed for a mechanical leg’s driving joint. Subsequently, the system is analyzed theoretically, and a semi-active control strategy is designed and simulated. Finally, the vibration and impact resistance of the prototype were tested. The experimental results show that in the signal tracking experiment, the maximum overshoot under semi-active control was reduced by 53.0%, and the settling time was reduced by 76.9% compared with the passive control. The impact test reduced the maximum displacement fluctuation by 41.09%, and the buffer time is only 0.24 s.

Energy harvesting from vibrations of a beam under moving mass using auxetic cantilever beams: Theoretical and experimental investigations

Recent research aims to enhance piezoelectric energy harvesting for low-power electronic circuits like sensors and wireless systems using cantilever energy harvesters with piezoelectric substrates featuring auxetic structures such as reentrant, missing rib, and double arrowhead patterns. Employing the Wentzel–Kramers–Brillouin (WKB) method is a novel method to analyze these structures based on Euler–Bernoulli beam theory. The study comprises theoretical analysis, finite element simulations, and experimental tests. The highest power output is achieved when consecutive masses excite the bridge using the double arrowhead auxetic unit cell substrate, yielding power outputs of 1.152 μ W / N . The effect of increasing unit cells has also been investigated. Highlights Creating unique analytical methods for auxetic substrate use in energy harvesters. Analyzing three auxetic harvester substrates, emphasizing their unique performance. Auxetic harvesters were studied under various bridge simulator base excitations. The study examines three auxetic structures' effect on harvested power. Study of moving masses' influence on bridge simulator, weights, and velocities.

The evaluation of N-OSS (N-oleoyl sarcosine) as an efficient collector in the flotation of spodumene from albite at low temperature: Experimental tests and atom-level calculation

In this study, N-OSS was explored as an efficient collector in the flotation of spodumene from albite. The flotation behaviors were examined by micro-flotation tests and the interaction mechanisms were comprehensively uncovered from atomical scale. It indicated N-OSS could effectively collect spodumene from albite at low temperature and N-OSS was more inclined to adsorb on spodumene surface than that on albite surface, thus significantly expanding the hydrophobicity difference. X-ray photoelectron spectroscopy (XPS) analysis suggested that N-OSS chemically interacted with both Ca and Al active sites on Ca-activated spodumene surface. Whereas, it weakly adsorbed on Ca-activated albite. Density functional theory (DFT) calculations reconfirmed that the adsorption of N-OSS on Ca-activated spodumene surface was more favorable than that on albite surface. The strong adsorption on spodumene was due to the hybridization reaction between the O 2p orbitals of C-O and C=O groups of N-OSS with Ca 4s orbitals as well as Al 3s orbitals on spodumene surface. Nevertheless, N-OSS weakly interacted with Ca atoms on Ca-activated albite due to steric hindrance. N-OSS exhibited selective collecting ability at low temperature in the flotation of spodumene from albite compared with conventional collector, which has promising prospects in the low-temperature flotation of spodumene from albite.

Predicting distribution of aeolian vibration amplitude of undamped overhead transmission lines

The most widely accepted estimation procedure of the severity of aeolian vibration is by calculating the maximum oscillation amplitudes of the conductor using Energy Balance Principle (EBP). However, the EBP is based on wind tunnel results where only one frequency is excited, while observations and experimental results show that multiple resonant modes are excited simultaneously. Furthermore, the required number of cycles of each amplitude level is not provided by current EBP-based methods. In this paper, vibration data from an experimental undamped ACSR Bersfort test line in Quebec, Canada, is recorded and analyzed. For each record of aeolian vibrations, amplitudes are fitted to a Rayleigh distribution based on the narrow-band assumption. The number of cycles and Rayleigh parameter are then related to wind conditions through a modified Strouhal frequency and EBP methodology. A statistical model is proposed to relate vibration profiles and wind input while considering wind turbulence intensity. The proposed method performs well and gives accurate estimates of both vibration amplitudes and number of cycles for ACSR Bersfort conductor. Physical and statistical theory is provided for each step of the method in order to extend the application of the method to other types of conductors or different line configurations.

Experimental testing of two urban stressors on freshwater biofilms

Aquatic ecosystems and their communities are exposed to numerous stressors of various natures (chemical and physical), whose impacts are often poorly documented. In urban areas, the use of biocides such as dodecyldimethylbenzylammonium chloride (DDBAC) and their subsequent release in wastewater result in their transfer to urban aquatic ecosystems. DDBAC is known to be toxic to most aquatic organisms. Artificial light at night (ALAN) is another stressor that is increasing globally, especially in urban areas. ALAN may have a negative impact on photosynthetic cycles of periphytic biofilms, which in turn may result in changes in their metabolic functioning. Moreover, studies suggest that exposure to artificial light could increase the biocidal effect of DDBAC on biofilms. The present study investigates the individual and combined effects of DDBAC and/or ALAN on the functioning and structure of photosynthetic biofilms. We exposed biofilms in artificial channels to a nominal concentration of 30 mg.L–1 of DDBAC and/or ALAN for 10 days. ALAN modified DDBAC exposure, decreasing concentrations in the water but not accumulation in biofilms. DDBAC had negative impacts on biofilm functioning and structure. Photosynthetic activity was inhibited by > 90% after 2 days of exposure, compared to the controls, and did not recover over the duration of the experiment. Biofilm composition was also impacted, with a marked decrease in green algae and the disappearance of microfauna under DDBAC exposure. The integrity of algal cells was compromised where DDBAC exposure altered the chloroplasts and chlorophyll content. Impacts on autotrophs were also observed through a shift in lipid profiles, in particular a strong decrease in glycolipid content was noted. We found no significant interactive effect of ALAN and DDBAC on the studied endpoints.

Axial compression performance of partially encased concrete columns with web opening

The objective of this study is to comprehensively assess the behavior of partially encased concrete (PEC) columns with web openings under axial compression. The primary objectives of this study are to analyze damage patterns and investigate the influence of key parameters, such as concrete strength, opening rate, and opening shape, on the ductility index and ultimate load-carrying capacity. The study employs experimental testing to examine the response of the PEC columns, with a particular focus on the mechanisms of concrete fracture and flange flexing. Notably, the study reveals a significant impact of the opening rate on the bearing capacity, while the effect of opening shape is comparatively minor. Furthermore, computational analyses are conducted to deepen the understanding of structural behavior. The study builds upon existing research to propose a novel method for calculating the bearing capacity of PEC columns with web openings. This method introduces two discount factors to enhance predictive accuracy.

Innate Orientating Behavior of a Multi-Legged Robot Driven by the Neural Circuits of C. elegans.

The objective of this research is to achieve biologically autonomous control by utilizing a whole-brain network model, drawing inspiration from biological neural networks to enhance the development of bionic intelligence. Here, we constructed a whole-brain neural network model of Caenorhabditis elegans (C. elegans), which characterizes the electrochemical processes at the level of the cellular synapses. The neural network simulation integrates computational programming and the visualization of the neurons and synapse connections of C. elegans, containing the specific controllable circuits and their dynamic characteristics. To illustrate the biological neural network (BNN)'s particular intelligent control capability, we introduced an innovative methodology for applying the BNN model to a 12-legged robot's movement control. Two methods were designed, one involving orientation control and the other involving locomotion generation, to demonstrate the intelligent control performance of the BNN. Both the simulation and experimental results indicate that the robot exhibits more autonomy and a more intelligent movement performance under BNN control. The systematic approach of employing the whole-brain BNN for robot control provides biomimetic research with a framework that has been substantiated by innovative methodologies and validated through the observed positive outcomes. This method is established as follows: (1) two integrated dynamic models of the C. elegans' whole-brain network and the robot moving dynamics are built, and all of the controllable circuits are discovered and verified; (2) real-time communication is achieved between the BNN model and the robot's dynamical model, both in the simulation and the experiments, including applicable encoding and decoding algorithms, facilitating their collaborative operation; (3) the designed mechanisms using the BNN model to control the robot are shown to be effective through numerical and experimental tests, focusing on 'foraging' behavior control and locomotion control.

Utility of the Morgan Fingerprint in Structure-Based Virtual Ligand Screening.

In modern drug discovery, virtual ligand screening (VLS) is frequently applied to identify possible hits before experimental testing and refinement due to its cost-effective nature for large compound libraries. For decades, efforts have been devoted to developing VLS methods with high accuracy. These include the state-of-the-art FINDSITE suite of approaches FINDSITEcomb2.0, FRAGSITE, and FRAGSITE2 and the meta version FRAGSITEcomb that were developed in our lab. These methods combine ligand homology modeling (LHM), traditional ligand similarity methods, and more recently machine learning approaches to rank ligands and have proven to be superior to most recent deep learning and large language model-based approaches. Here, we describe further improvements to our previous best methods by combining the Morgan fingerprint (MF) with the originally used PubChem fingerprint and FP2 fingerprint. We then benchmarked FINDSITEcomb2.0M, FRAGSITEM, FRAGSITE2M, and the composite meta-approach FRAGSITEcombM. On the 102 target DUD-E set, the 1% enrichment factor (EF1%) and area under the precision-recall curve (AUPR) of FRAGSITEcomb increased from 42.0/0.59 to 47.6/0.72. This 0.72 AUPR is significantly better than that of the state-of-the-art deep learning-based method DenseFS's AUPR of 0.443. An independent test on the 81 targets DEKOIS2.0 set shows that EF1%/AUPR increases from 18.3/0.520 to 23.1/0.683. An ablation investigation shows that the MF contributes to most of the improvement of all four approaches. Thus, the MF is a useful addition to structure-based VLS.

Thermal Optimization Strategies for Li-Ion Batteries: Predictive Temperature Algorithm

Abstract Performance, safety, and longevity of batteries are all strongly impacted by thermal management, which is an essential component of battery design and operation. This work examines how accurate temperature control can result in significant improvements in performance and reliability with a focus on battery thermal heating. Predicting the temperature achieved by the battery during operation not only avoids conditions that lead to thermal runaway but also guarantees that the battery is used optimally within an optimal temperature range. Within the optimal temperature range, several advantages are observed. First, battery efficiency improves significantly as electrochemical processes occur more efficiently. Furthermore, by lowering the possibility of short circuits and improving overall battery safety, thermal stability aids in the prevention of undesirable phenomena like dendrite growth. By lessening the deterioration brought on by thermal degradation processes, thermal optimization also affects battery longevity. Based on experimental tests, a finite element method (FEM) model is developed. A model for thermal runaway propagation is established by combining thermal runaway and conduction models with an Arrhenius law-based combustion model. The study employed a cylindrical Li-ion cell to conduct tests, taking into account three parameters: discharge rate (CRate), ambient temperature (Tamb), and initial battery temperature (T0). An algorithm based on the three variables was developed using the simulation results. The algorithm enables the accurate prediction of rising battery temperature during use, facilitating the setting of an optimal maximum discharge rate considering initial and ambient temperatures, thereby ensuring optimal performance within the desired temperature range.