Stress Testing Experiment Research Articles

Consistently increased dorsolateral prefrontal cortex activity during the exposure to acute stressors.

Stress has a major impact on our mental health. Nonetheless, it is still not fully understood how the human brain responds to ongoing stressful events. Here, we aimed to determine the cortical dynamics during the exposure to ecologically valid, standardized stressors. To this end, we conducted 3 experiments in which healthy participants underwent the Trier Social Stress Test (experiments 1 and 2) and the Socially Evaluated Cold Pressor Test (experiment 3) or a respective control manipulation, while we measured their cortical activity using functional near-infrared spectroscopy. Increases in salivary cortisol and subjective stress levels confirmed the successful stress induction in all experiments. Results of experiment 1 showed significantly increased cortical activity, in particular in the dorsolateral prefrontal cortex, during the exposure to the Trier Social Stress Test. Experiment 2 replicated this finding and showed further that this stress-related increase in dorsolateral prefrontal cortex activity was transient and limited to the period of the Trier Social Stress Test. Experiment 3 demonstrated the increased dorsolateral prefrontal cortex activity during the Socially Evaluated Cold Pressor Test, suggesting that this increase is generalizable and not specific to the Trier Social Stress Test. Together, these data show consistently that dorsolateral prefrontal cortex activity is not reduced, as commonly assumed, but increased under stress, which may promote coping with the ongoing stressor.

Compositional Evaluation on Japanese Textual Entailment and Similarity

Abstract Natural Language Inference (NLI) and Semantic Textual Similarity (STS) are widely used benchmark tasks for compositional evaluation of pre-trained language models. Despite growing interest in linguistic universals, most NLI/STS studies have focused almost exclusively on English. In particular, there are no available multilingual NLI/STS datasets in Japanese, which is typologically different from English and can shed light on the currently controversial behavior of language models in matters such as sensitivity to word order and case particles. Against this background, we introduce JSICK, a Japanese NLI/STS dataset that was manually translated from the English dataset SICK. We also present a stress-test dataset for compositional inference, created by transforming syntactic structures of sentences in JSICK to investigate whether language models are sensitive to word order and case particles. We conduct baseline experiments on different pre-trained language models and compare the performance of multilingual models when applied to Japanese and other languages. The results of the stress-test experiments suggest that the current pre-trained language models are insensitive to word order and case marking.

Inducing and Recording Acute Stress Responses on a Large Scale With the Digital Stress Test (DST): Development and Evaluation Study.

BackgroundValuable insights into the pathophysiology and consequences of acute psychosocial stress have been gained using standardized stress induction experiments. However, most protocols are limited to laboratory settings, are labor-intensive, and cannot be scaled to larger cohorts or transferred to daily life scenarios.ObjectiveWe aimed to provide a scalable digital tool that enables the standardized induction and recording of acute stress responses in outside-the-laboratory settings without any experimenter contact.MethodsOn the basis of well-described stress protocols, we developed the Digital Stress Test (DST) and evaluated its feasibility and stress induction potential in a large web-based study. A total of 284 participants completed either the DST (n=103; 52/103, 50.5% women; mean age 31.34, SD 9.48 years) or an adapted control version (n=181; 96/181, 53% women; mean age 31.51, SD 11.18 years) with their smartphones via a web application. We compared their affective responses using the international Positive and Negative Affect Schedule Short Form before and after stress induction. In addition, we assessed the participants’ stress-related feelings indicated in visual analogue scales before, during, and after the procedure, and further analyzed the implemented stress-inducing elements. Finally, we compared the DST participants’ stress reactivity with the results obtained in a classic stress test paradigm using data previously collected in 4 independent Trier Social Stress Test studies including 122 participants overall.ResultsParticipants in the DST manifested significantly higher perceived stress indexes than the Control-DST participants at all measurements after the baseline (P<.001). Furthermore, the effect size of the increase in DST participants’ negative affect (d=0.427) lay within the range of effect sizes for the increase in negative affect in the previously conducted Trier Social Stress Test experiments (0.281-1.015).ConclusionsWe present evidence that a digital stress paradigm administered by smartphone can be used for standardized stress induction and multimodal data collection on a large scale. Further development of the DST prototype and a subsequent validation study including physiological markers are outlined.

Finite element analysis of excavator mechanical behavior and boom structure optimization

The mechanical behavior analysis of the excavator and structure optimization of the excavator boom are conducted in this paper. By incorporating the local coordinate system established on each excavator component into the predefined global coordinate system, a parametric finite element model (FEM) of the whole excavator is developed first. Three-dimensional (3D) 20-node high-order solid brick element is used for structure discretization. Multipoint constraint element and link element are applied to simulate the telescopic behavior of the hydraulic cylinder, and the shaft-through method is developed for the numerical analysis of the pin connections of the excavator components. Given the whole FEM of the excavator, the boundary constraints can be established accurately according to the actual working condition. Then stress test experiments are subsequently implemented to verify the effectiveness of the proposed FEM, and the results show that the numerical results from the proposed FEM are in good agreement with experiment results. Lastly based on the validated FEM, the structure optimization of the excavator boom is conducted to improve the mechanical properties. The numerical analysis results show that the load bearing capacity of the boom can be improved effectively through the structure optimization.

Simulational and experimental study of stress in bolts work-piece

In order to study the effect of different bolts tightening sequences on the stress of bolts work-piece, the finite element simulation and stress test experiments are adopted. Three types of bolt work-piece: two, five, and frame type bolts work-pieces are studied under different tightening sequences. The stress values and distribution are obtained under different tightening sequences by simulation. It is observed that the stress distribution tendency of bolts work-piece has little change under different tightening sequences. It also notices that the tightening sequences have no effect on two bolts work-piece due to the symmetry of work-piece. In five bolts work-piece, the variation range of stress under tightening from ends to middle is smaller than that under sequence tightening, which indicates that better stress uniformity is obtained under tightening from ends to middle in five bolts work-piece. Similarly, in frame bolts work-piece, the variation range of stress under symmetrical tightening is smaller than that under sequence tightening, which indicates that better stress uniformity is obtained under symmetrical tightening in frame type bolts work-piece. Furthermore, the experimental results are in good agreement with the simulation results. Moreover, the stress variation mechanism is revealed by analyzing residual preload variation under sequence tightening.

Fractional Order BPNN for Estimating State of Charge of Lithium-ion Battery under Temperature Influence

Abstract State of charge (SOC) estimation for lithium-ion battery (LIB) is always a vital issue for battery management system (BMS) of LIBs. Due to the complex nonlinear characteristics of LIBs, data-driven model and estimation methods have been proposed. Among them, back propagation neural network (BPNN) is one of the widely used machine learning (ML) method. To enhance the performance of BPNN of LIBs, a fractional-order BPNN (FO BPNN) based on fractional-order gradient method is designed for SOC estimation of LIB in this paper. Moreover, temperature acting as key factor is also taken into consideration. Hence, the charging or discharging current, voltage, and temperature are applied as the inputs of the proposed FO BPNN, and SOC is obtained from the network. By Dynamic Stress Test (DST) experiments under five different temperatures of four 18650 LIBs, it proves that the proposed FO BPNN is able to estimate SOC of LIBs accurately in a data-driven way.

Compatibility of ticagrelor with pharmaceutical excipients studied with thermal and spectroscopic techniques.

The compatibility between ticagrelor and selected excipients (mannitol, calcium phosphate tribasic, sodium carboxymethyl starch, hydroxypropyl cellulose and magnesium stearate) was investigated by differential scanning calorimetry. The compatibility was further corroborated by Raman spectroscopy and isothermal stress testing experiments. These results revealed that ticagrelor has high compatibility with mannitol, calcium phosphate tribasic, sodium carboxymethyl starch, hydroxypropyl cellulose and magnesium stearate.

Stress dependent degradation mechanisms on commercially available GaN Normally-Off transistors

In this paper, a series of stress test experiments were carried out on GaN Normally-Off COTS transistors (eGaN-on-Si) accelerating the normal degradation process through the use of elevated temperature and biasing conditions. The primary objective is to build a predictive model of the reliability of such GaN electronic components used in power conversion. The experiments were performed on 80 samples allocated in: i) four conditions of DC off-state and on-pulsed step stress sequences, ii) three high temperature off-state endurance lifetest sequences, iii) and three on-pulsed lifetest sequences. These series of high temperature step stress and lifetest conditions allow to identify and separate the infant mortality from the random to wear-out mechanisms occurring in accelerated DC off state, forward-gate and pulsed high current drain testing. Eyring model was determined based on Weibull plot data analysis allowing to quantify a wearout failure mechanism consisting in the shortening of the gate junction. The n factor of the inverse power law of the off-state voltage at 150 °C channel was determined to be 7. On-pulsed experiments carried out at Idspulse = 16A for 3 junction temperatures demonstrated Rdson degradation and an activation energy of 1.28 eV (failure criteria 50% drift on Idsonmax).

Simulation and experimental analysis of critical stress regions of deep-water annular blowout preventer

In deep-water drilling for oil and gas, the annular blowout preventer (BOP) is subjected to sustained high pressure or impact loads, causing the concentration of stress in some regions, which can easily cause cracks or fatigue damage. The top cover and housing of the annular BOP are the main pressure-containing parts. Once they fail during the emergency shut-in process, a blowout accident will occur, and there may be casualties and major economic losses. Therefore, the stress concentration regions of the top cover and the housing must be analysed to ensure safe operation. In this study, a high-fidelity approach to monitor the stress was established. This approach combines the theoretical calculation method (TCM), finite-element analysis (FEA) and stress testing experiment (STE). The stress distribution laws of the top cover and housing were measured under the rated working pressure and hydrostatic test pressure. The results indicated that the TCM, FEA, and STE exhibited the same curve trend of stress. Moreover, the FEA results were almost identical to the STE results for the stress values of testing points. The FEA results indicated that there were two critical stress regions in the housing. These were regions where cracks and failures had actually occurred in the past. The main technical contribution of the study is that it may serve as the basis for additional investigations into abandonment evaluation, fatigue analysis, and residual life evaluation.

Adaptive Forgetting Factor Recursive Least Square Algorithm for Online Identification of Equivalent Circuit Model Parameters of a Lithium-Ion Battery

With the popularity of electric vehicles, lithium-ion batteries as a power source are an important part of electric vehicles, and online identification of equivalent circuit model parameters of a lithium-ion battery has gradually become a focus of research. A second-order RC equivalent circuit model of a lithium-ion battery cell is modeled and analyzed in this paper. An adaptive expression of the variable forgetting factor is constructed. An adaptive forgetting factor recursive least square (AFFRLS) method for online identification of equivalent circuit model parameters is proposed. The equivalent circuit model parameters are identified online on the basis of the dynamic stress testing (DST) experiment. The online voltage prediction of the lithium-ion battery is carried out by using the identified circuit parameters. Taking the measurable actual terminal voltage of a single battery cell as a reference, by comparing the predicted battery terminal voltage with the actual measured terminal voltage, it is shown that the proposed AFFRLS algorithm is superior to the existing forgetting factor recursive least square (FFRLS) and variable forgetting factor recursive least square (VFFRLS) algorithms in accuracy and rapidity, which proves the feasibility and correctness of the proposed parameter identification algorithm.

Tractors Hydraulics System Stress Testing Design and Experiment

This paper aims to research and analysis the tractor hydraulic suspension system stress. The hydraulics system was hooked on the latest developed hillside tractor chassis, this experiment used load test method and portable hydraulic testing instrument to test the cylinder movement process and force process. It can be concluded from the drawn curve that when the system loads 2940 Newton, the maximum working pressure is 4.4Mpa. When the system loaded 3920 Newton, the maximum load is 4.8Mpa. The pressure difference between the left and right levers is 2Mpa. The conclusion can provide data validation for the simulation analysis of tractor suspension system as well as an effective reference for the design scheme of tractor suspension system.

The Degradation Chemistry of Farglitazar and Elucidation of the Oxidative Degradation Mechanisms

The chemical degradation of farglitazar (1) was investigated using a series of controlled stress testing experiments. Farglitazar drug substance was stressed under acidic, natural pH, basic, and oxidative conditions in solution. In the solid state, the drug substance was stressed with heat, high humidity, and light. Farglitazar was found to be most labile toward oxidative stress. A series of mechanistic experiments are described in which the use of 18O-labelled oxygen demonstrated that oxidative degradation of farglitazar is caused primarily by singlet oxygen formed under thermal conditions. Major degradation products were isolated and fully characterized. Mechanisms for the formation of degradation products are proposed. Drug product tablets were also stressed in the solid state with heat, high humidity, and light. Stressed tablets afforded many of the same degradation products observed during drug substance stress testing, with oxidation again being the predominant degradation pathway. Evidence for the activity of singlet oxygen, formed during thermal stress testing of the solid oral dosage form, is presented. The degradation pathways observed during stress testing matched those observed during long-term stability trials of the drug product.

Strategies To Address Mutagenic Impurities Derived from Degradation in Drug Substances and Drug Products

This paper outlines strategies in alignment with ICH M7 for systematically assessing the potential risk posed by mutagenic degradants in active pharmaceutical ingredients (API) and formulated products. A mutagen risk assessment (MRA) process that involves degradation should include results from focused drug substance and drug product stress testing experiments (e.g., at elevated temperature, a wide pH range in solution, oxidative, and photolytic stress) as well as accelerated and long-term stability studies in the solid-state. While the MRA may include hypothetical (theoretically predicted) degradation products from computer based and/or knowledge-based approaches, investigations for numerous hypothetical degradation products whose significance have not been verified experimentally should not be initiated based on these results alone. Drug substance and drug product stress (forced degradation) studies should be designed to generate a comprehensive range of potential degradants that encompass all degradati...

Study on stress distribution of a subsea Ram BOP body based on simulation and experiment

Taking a double ram blowout preventer (Ram BOP) 2FZ54-105 as an example, we have analyzed the stress distribution rule and the stress concentration regions of its body under the rated working conditions (RWC) and the hydrostatic test pressure (HTP) with the finite element analysis (FEA) methods and the stress testing experiment (STE) methods. And then it was found that the simulation results of the FEA were essentially consistent with the STEs through the comparative analysis, and the feasibility and accuracy of these two methods are corroborated each other. Moreover, we confirm that the body strength meets the design requirements and using conditions by combining with the analysis results of two methods. Finally, the stress concentration regions of inner and outer surfaces of the body were summarized and gained based on the comprehensive analysis of all cases. These methods and results in this study can provide references for structure modified design of the body and guide on-site maintenance and safety evaluation of the Ram BOP in service.

Microstructural and Mechanical Characterization of Catalyst Coated Membranes Subjected to In Situ Hygrothermal Fatigue

Catalyst coated membranes (CCMs) in polymer electrolyte fuel cells are subjected to mechanical stresses in the form of fatigue and creep that deteriorate the durability and lifetime of the cells. The present article aims to determine the effect of in-situ hygrothermal fatigue on the microstructure and mechanical properties of the CCM. The fatigue process is systematically explored by the application of two custom-developed accelerated mechanical stress test (AMST) experiments with periodic extraction of partially degraded CCMs. Cross sectional and top surface scanning electron microscope (SEM) images of the end-of-test CCMs reveal the formation of mechanically induced cracks and delamination due to cyclic tensile and compressive fatigue stress. Tensile and expansion tests are conducted at different stages of degradation to evaluate the evolution in the mechanical and hygrothermal properties of the CCM. The tensile test results indicate gradual reductions in final strain, ultimate tensile strength, and fracture toughness with increasing number of fatigue cycles. The decay in tensile properties is attributed to the microstructural damage and micro-cracks formed during the AMST. Moreover, it is shown that the hygrothermal expansion of the CCM is more sensitive to conditioning than mechanical degradation.

Numerical Simulation and Stress Testing Research on Elliptical Bipolar Linear Shaped Charge

Based on shaped charge technology, the method of linear cracks of directional fracture in rocks controlled blasting by shaped charge and the elliptical bipolar linear shaped charge with low detonation velocity explosive was presented in this paper. The stress testing experiment was carried on by the stress sensor for analyzing the characters of cumulative pre-splitting of the shaped charge. A numerical calculation scheme for simulating the formation and movement of jet was developed based on the ansys/ls-dyna. The damage of the concrete target penetrated by the jet was showed in the numerical simulation. The results of experiment and the simulation indicted that the shaped charge can form good effect on cumulative energy and produce good pre-splitting blasting effect. At the same time, the safe, economic and environmental benefits had been clearly made.

The microanalysis of the bonding condition between coated diamond and matrix

Ti, Mo, and Cu were plated on the diamond surface by magnetron sputtering method. The compression strength of Ti-coated diamond was measured; the structure of the diamond surface after vacuum heat treatment was analyzed by XPS. By the SEM analysis and the bending stress testing experiments, the authors researched the interface bonding condition of the coated diamond. The research revealed that the coatings on the diamond surface can protect the diamond well, and they also avoided or decreased the erosion of the diamond by matrix. The bonding strength between the diamond and the matrix was improved after plated Ti and Mo, but it was greatly influenced by the matrix composition and the hot-pressing technics. The plated metal and diamond could form local chemical union at the hot-pressing temperature of 830–840 °C.

Environmental stress testing experiment using the Taguchi method : DENNIS E. PACHUCKI. IEEE Transactions on Components, Packaging, and Manufacturing Technology, Part A, 18(1), 3 (March 1995)

Environmental stress testing experiment using the Taguchi method : DENNIS E. PACHUCKI. IEEE Transactions on Components, Packaging, and Manufacturing Technology, Part A, 18(1), 3 (March 1995)

Environmental stress testing experiment using the Taguchi method

Environmental stress testing experiment using the Taguchi method

Identification of stabilizing and destabilizing effects of excipient-drug interactions in solid dosage form design

The compatibility of pyridoxal hydrochloride with various tableting excipients has been investigated by isothermal stress testing of multicomponent mixtures and by differential scanning calorimetry (DSC) screening of binary drug excipient mixtures. A Plackett-Burman factorial design was used to conduct the isothermal stress testing experiment. Elevated moisture and temperature were found to be the dominant destabilizing factors. The factorial design experiment also revealed chemical incompatibilities with mannitol, lactose and corn starch. Simultaneously, the strong stabilizing influences of various cellulose derivatives and colloidal silicone dioxide were identified. It appears that these excipients function as moisture scavengers, thus decreasing the amount of free water available for interaction with pyridoxal hydrochloride. The major incompatibilities were also detected by DSC screening. The study demonstrates the value of employing a compatibility screening procedure capable of detecting both positive and negative drug-excipient interactions.