Test Procedure Research Articles

A Varying-Coefficient Additive Hazard Model for Recurrent Events Data.

The additive hazard model, which focuses on risk differences rather than risk ratios, has been widely applied in practice. In this paper, we consider an additive hazard model with varying coefficients to analyze recurrent events data. The model allows for both varying and constant coefficients. We first propose an estimating equation-based approach with spline basis smoothing for all functional coefficients. Then, we provide theoretical justifications for the resulting estimates, including consistency, rate of convergence, and asymptotic distribution. Furthermore, we construct a Cramér-von Mises test procedure to investigate whether the functional coefficients should be treated as constant, and its asymptotic null distribution is also derived. Extensive simulation experiments are conducted to evaluate the finite-sample performance of the proposed approaches. A Chronic Granulotamous Disease data set was analyzed to illustrate our methodology.

The impact of graphene reinforcement on z-pin and adhesively bonded composite for enhancing flexural strength of co-cured single lap joints

ABSTRACT The present work presents an investigation into the flexural characteristics of a composite joint consisting of various volume percent of carbon fiber reinforced polymer (CFRP) Z-pins inserted into a glass fiber reinforced polymer (GFRP) Co-cure single lap composite joint (CC-SLJ). The flexural strength of a single lap joint (SLJ) with 2.5 volume percent (vol%) CFRP Z-Pin is higher than that of other reinforcements with different Z-pin volume percentages. The bending strength of the SLJ was examined using an optimized 2.5 volume percent of Z-Pin with varying pin alignment (30°, 45°, 60°, and 90°), and it was found that 90° orientation showed good improvement in flexural strength. Compared to plain SLJ, 1.25% graphene nanoparticles (GNP) incorporated CC-SLJ significantly increased the flexural strength by 45.59%. SLJ with dual reinforcement of the 2.5 vol% CFRP Z-pin with 1.25 wt.% GNP exhibited high bending strength and multi-reinforcement of epoxy/GNP adhesive, and CFRP Z-pin and graphene-reinforced Z-pin were found with higher flexural strength enhancement. The results of the three-point bending test indicated a decrease in Z-pin strength and stiffness as the volume percentage of the pin increases. The specimen’s fractured surface was examined under a microscope following the testing procedure, and the images were captured to detect any indications of failure. It was found that adding graphene nanoparticles (GNP) and Z pins to the single lap joint (SLJ) makes the surface rougher and easier for the adhesive and adherend to stick to each other.

White Noise and Its Misapplications: Impacts on Time Series Model Adequacy and Forecasting

This paper contributes significantly to time series analysis by discussing the empirical properties of white noise and their implications for model selection. This paper illustrates the ways in which the standard assumptions about white noise typically fail in practice, with a special emphasis on striking differences in sample ACF and PACF. Such findings prove particularly important when assessing model adequacy and discerning between residuals of different models, especially ARMA processes. This study addresses issues involving testing procedures, for instance, the Ljung–Box test, to select the correct time series model determined in the review. With the improvement in understanding the features of white noise, this work enhances the accuracy of modeling diagnostics toward real forecasting practice, which gives it applied value in time series analysis and signal processing.

Critical review of chronic toxicity testing approaches with the saltwater mysid (Americamysis bahia) used in pesticide registration.

The United States Environmental Protection Agency (USEPA) has a conditional requirement for a chronic toxicity test with mysids (Americamysis bahia) for registration of pesticide products. Achieving performance acceptability criteria in control treatments for this study can be challenging because the current draft test guideline, which was published in 1996 under USEPA Office of Prevention, Pesticides, and Toxic Substances (OPPTS) 850.1350, Mysid Chronic Toxicity Test, provides limited information on study design and conduct. This critical review was undertaken to 1) identify areas of inconsistency in acceptability criteria between the 1996 draft OPPTS test guideline and ASTM International test guidance, 2) highlight areas that require additional clarification, 3) discuss areas that are impractical or have uncertain scientific relevance regarding the objectives of the test, and 4) provide recommendations for revision of the draft OPPTS test guideline. To achieve this, 116 final study reports from chronic mysid toxicity tests conducted over approximately the past 30 years were collected. From these reports, survival, growth, and reproduction data from negative and solvent control groups were compiled. Through investigation of trends in the data, it became apparent that no-observed-effect-concentrations (NOECs) were most commonly based on reproductive endpoints, followed by adult growth endpoints and adult survival. Notably, less than 1% of studies had a NOEC based solely on a second-generation measurement endpoint. Analysis of this comprehensive data set provided clarity on the establishment of acceptability criteria for the study and elements of the testing procedure that can be streamlined without loss of critical information, which resulted in a set of recommendations to improve future versions of the chronic mysid toxicity test guideline.

Investigation of Layer Thickness Effects on Mechanical Properties of PLA Using FDM Additive Manufacturing

This study explores the influence of layer thickness on the mechanical properties of Polylactic Acid (PLA) fab- ricated using Fused Deposition Modeling (FDM) additive manufacturing. By systematically varying the layer thickness, the aim to understand how these changes affect tensile strength, elasticity, and overall structural integrity of the printed components. The research employs a series of controlled experiments, utilizing standardized testing procedures to mea- sure and analyze the mechanical performance of PLA specimens. Results indicate significant variations in mechanical properties correlating with different layer thicknesses, providing valuable insights for optimizing print parameters in FDM processes. These findings contribute to the broader knowledge base, guiding the design and manufacturing of more robust and reliable 3D-printed objects.

Performance of Three Continuous Glucose Monitoring Systems in Adults With Type 1 Diabetes.

The performance of continuous glucose monitoring (CGM) systems is difficult to compare due to different study designs and a lack of head-to-head studies. This study evaluated the performance of FreeStyle Libre 3 (FL3), Dexcom G7 (DG7), and Medtronic Simplera (MSP) against different comparator methods and during clinically relevant glycemic scenarios. Twenty-four adult participants with type 1 diabetes mellitus wore one sensor of each CGM system in parallel for up to 15 days. Sensors of DG7 and MSP were exchanged on days 5 and 8, respectively. Three 7-hour sessions with 15-minute comparator blood glucose-level measurements using YSI 2300 (YSI, venous), Cobas Integra (INT, venous), and Contour Next (CNX, capillary) were conducted on days 2, 5, and 15. Simultaneously, glucose-level excursions with transient hyperglycemia and hypoglycemia were induced according to a recently published testing procedure. The accuracy was evaluated using various metrics, including mean absolute relative differences (MARDs). Compared with YSI data, the MARDs of FL3, DG7, and MSP were 11.6%, 12.0%, and 11.6%, respectively. Relative to the INT data, the corresponding MARDs were 9.5%, 9.9%, and 13.9%, respectively, and compared with CNX data, MARDs were 9.7%, 10.1%, and 16.6%, respectively. Both FL3 and DG7 showed better accuracy in the normoglycemic and hyperglycemic range, while MSP performed better in the hypoglycemic range. Performance results of all CGM systems varied depending on the comparator method. However, across comparators FL3 and DG7 tended to be more accurate compared with MSP. All CGM systems showed a lower accuracy compared with previous studies, emphasizing the need for comprehensive study design guidelines.

Testing Protocols and Procedures for Undertaking Fire Resistance Tests on Concrete Structures Incorporating Fiber-Reinforced Polymers

Fiber-reinforced polymers (FRPs) are often incorporated as internal (primary) reinforcement in new concrete constructions or as external (secondary) reinforcement in retrofitting and strengthening of existing concrete structures. Under fire conditions, the response of FRP-incorporated concrete structures are altered due to the presence of FRPs; thus, their fire performance is different from that of concrete structures with conventional metallic reinforcement. However, the fire resistance of these FRP-incorporated structural members continues to be evaluated through standard fire resistance tests, which are similar to conventional steel and concrete structural members. Despite the complexity of this testing approach and its drawbacks, standard fire testing remains a cornerstone in evaluating FRP-incorporated concrete structural members. Thus, this paper sheds more light on the fire testing procedure and discusses the distinctive factors that differentiate the fire performance of FRP-incorporated concrete structures from that of conventional concrete structures and the need for additional provisions to test such structures. To address the current shortcomings, a set of additional testing protocols and procedures for undertaking fire resistance tests on FRP-incorporated concrete structural members are presented. The performance criteria to be applied to evaluate the failure of FRP–RC structural members under fire conditions are discussed.

Test engines for the asset administration shell

Abstract The Asset Administration Shell (AAS) is a standard for Digital Twins, a key element of Industry 4.0. In order to realize interoperability as its central prerequisite, manufacturers must implement the formal AAS metamodel specification correctly down to the last detail. To ensure this, conformance testing procedures should be defined and carried out as appropriate quality measures. This article presents comprehensive approaches to carry out formalized metamodel conformance tests for the AAS and its software components by describing the AAS Test Engines. First, the AAS software ecosystem is analyzed providing a systematic categorization of existing AAS software components. Based on these findings, basic building blocks and test setups needed for AAS conformance testing are identified. Then, implementation of these building blocks in the AAS Test Engines is described. Finally, usage, findings and limits of the presented methods based on a real-world case study from the AAS community are illustrated.

Operational Feasibility of Point-of-Care Testing for Sickle Cell Disease in Resource-Limited Settings of Tribal Sub-Plan Region of India

Background: Sickle cell disease (SCD) individuals in India are mostly identified when they become symptomatic. To provide a timely diagnosis of SCD to participants, healthcare workers should be competent in using the point-of-care test (POCT). In this study, we aimed to evaluate the competence of healthcare workers to screen infants and adult populations through POCT. Methodology: This study was conducted in pilot mode over 8 months from April to November 2023. A random sampling method was used to select ten auxiliary nursing midwives (ANMs), ten lab technicians (LTs), and five medical officers (MOs). Each selected ANM and LT was supposed to conduct ten tests and MOs to conduct five tests. The POCT used to diagnose sickle cell disease was HemoTypeSC. Results: Among the healthcare workers who participated in the study, 67% belonged to the scheduled tribes. When the ANM and LT competencies were compared for the pre-analytical phase (phase I), ANMs were more competent than the LTs. ANMs were more adept at handling people, whereas the LTs were more competent in conducting the test procedures. When the comparison was made for the analytical phase (phase II), both the ANMs and LTs were found to be equally competent. ANMs followed the standard operating procedure (SOP) more precisely than MOs and LTs. In the post-analytical phase, LTs were found to be more competent than ANMs. The approach used in this study with sub-centers and primary health centers (PHCs) appears to have encouraged the feasibility of the screening program. Conclusions: The results of this study conclude that the healthcare workers in the region are competent to perform the POCT for the diagnosis of sickle cell disease. The POCT may be introduced in the program for the diagnosis of SCD.

The Statistical Analysis of Social Networks and the Effect on Sleeping Quality of Undergraduate Students

The aim of this article is to study and examine how the different social networks were affecting the sleeping quality of undergraduate students. A case study was performed in Maharani Cluster University. The simple random sampling technique is used to select the samples and data is collected from selected samples through self-administered questionnaire. The suitable statistical tool called Pearson Chi-square test procedure is used to analyze the data and draw the inference based on p-value by using R-software.

An Analysis of Rock Bolt Dynamic Responses to Evaluate the Anchoring Degree of Fixation

Rock bolting in underground environments is used for different fundamental reasons, including suspending potentially loosened blocks, clamping small wedges together, inducing a protective pressure arch along the contour of excavated voids to improve the self-supporting capacity of the ground, and providing passive pressure in integrated support systems. In this study, we describe a testing procedure that was developed to investigate the grouted annulus of a rock bolt using a low-cost investigation method. This diagnostic technique was based on the dynamic response of the system, where mechanical vibrations were induced within the rock bolt and the response was recorded by using geophones/accelerometers on the protruding element of the bolt (the collar and head). The collected signal was then processed to estimate the spectral response, and the amplitude spectrum was analyzed to detect the resonance frequencies. A 3D finite element model of the rock bolt and grouting was established to simulate the quality of the coupling by varying the mechanical properties of the grouting. The model’s response for the studied geometry of the rock bolt suggested that a poor quality of grouting was usually associated with flexural modes of vibration with a low resonance frequency. Good-quality grouting was associated with a frequency higher than 1400 Hz, where the axial vibration was mainly excited. Our analyses referred to short rock bolts, which are usually adopted in small tunnels. The interpretation of the experimental measurements assumed that the spectral response was significantly affected by the quality of the grouting, as demonstrated by the modeling procedure. The resonant frequency was compared with the results of the model simulation. The method was used to test the quality of rock bolts in a small experimental tunnel carved from andesite rock in Chile. Low-cost shock sensors (piezoelectric geophones) with low sensitivity but a wide frequency band were used. The main research outcome was the development of a reliable method to model the dynamic response of rock bolts in mines or for experimental applications in tunnels. Albeit limited to the current specific geometries, the modeling and testing will be adapted to other anchor/bolt options.

Milk allergen quantification in rice flour: An experimental investigation of sampling and testing procedures.

Milk allergen quantification in rice flour: An experimental investigation of sampling and testing procedures.

A dataset for large prismatic lithium-ion battery cells (CALB L148N58A): Comprehensive characterization and real-world driving cycles.

This paper presents an experimental dataset for a batch of eleven prismatic CALB L148N58A lithium-ion B-grade battery cells with a nominal capacity of 58 Ah. The experimental campaign, conducted at the Energy Laboratory for Interdisciplinary Storage Applications (ELISA) at the University of Trieste, Italy, employs non-destructive tests to assess the performance of each cell within the batch. The cell-level testing procedures include fixed Constant Current Constant Voltage (CCCV) charging and Constant Current (CC) discharging at low current rates, Hybrid Pulse Power Characterization (HPPC) tests at various C-rates (i.e., 1C and C/3), Electrochemical Impedance Spectroscopy (EIS) at different State of Charge (SOC) levels, and three distinct driving cycles (WLTP, UDDS and US06). All the experiments were conducted at three different ambient temperatures (10°C, 25°C, and 40°C), resulting in a comprehensive dataset for assessing the performance metrics of the battery cells. This dataset provides valuable insights into post-manufacturing cell-to-cell variations in performance metrics such as capacity and impedance within a batch of fresh cells. Additionally, it serves as a crucial resource for developing battery models, including physics-based, empirical, and data-driven approaches. Moreover, it may contribute to validate model-based and data-driven estimation and control strategies within battery management systems, enhancing the reliability and efficiency of energy storage solutions.

Adjusted Inference for Multiple Testing Procedure in Group-Sequential Designs.

Adjustment of statistical significance levels for repeated analysis in group-sequential trials has been understood for some time. Adjustment accounting for testing multiple hypotheses is also well understood. There is limited research on simultaneously adjusting for both multiple hypothesis testing and repeated analyses of one or more hypotheses. We address this gap by proposing adjusted-sequential p-values that reject when they are less than or equal to the family-wise Type I error rate (FWER). We also propose sequential -values for intersection hypotheses to compute adjusted-sequential -values for elementary hypotheses. We demonstrate the application using weighted Bonferroni tests and weighted parametric tests for inference on each elementary hypothesistested.

Comprehensive investigation of the effects on fuel, performance and emission properties of modify fuel blends addition of graphene nanoplatelets to ternary fuel blends (diesel, waste cooking biodiesel, and butanol) in a diesel engine

Development of alternative fuels from organic waste for the applications in CI diesel engines is an important research area for a sustainable energy future. In CI diesel engines, binary and ternary fuel blends can be prepared by blending fossil diesel fuel with biodiesel and alcohols. In recent years, various fuel blends have been improved with different metal or non-metal nanoparticles. In this work, non-metallic Graphene Nanoplatelets (GNPs) were added to ternary fuel blends, followed by the characterization of the prepared samples. Subsequently, an investigation was conducted to examine their effects in engine performance and exhaust emissions. In this study, ternary blends were prepared by adding biodiesel obtained from the recycling of waste cooking oils and 10%, 15%, and 20% butanol to diesel fuel. Subsequently, 50 ppm of GNPs were added to these blends. Initially, the chemical properties of all fuel blends, such as cetane index, calorific value, density, and kinematic viscosity, were analyzed. Additionally, TG, DSC, FTIR, UV-VIS, and GS-FID characterizations were conducted for all fuel samples. Afterwards, engine performance, combustion characteristics, and exhaust emissions were performed. A total of 7 distinct fuel samples were employed in the engine testing procedure, wherein the engine was operated at 2 different speeds and 5 engine loads. The experiment results indicated that the lowest BSFC values occurred in diesel fuel under all conditions. With the addition of GNPs to the ternary fuels, the BSFC value decreased by an average of 1.11% at 1500rpm and 1.89% at 2000 rpm for all loads. Upon analysis of BTE values, it was revealed that diesel fuel had the greatest BTE value. The incorporation of GNPs into the ternary blends resulted in an average enhancement in BTE values of 1.40% at 1500rpm and 2.60% at 2000 rpm at all loads. The examination of the in-cylinder pressure and heat release rate indicated that the incorporation of GNPs led to a little decrease in the duration of the ignition delay. In the examination of NOx emissions, the inclusion of GNPs resulted in an average increase in emissions of 9.89% at 1500rpm and 5.37% at 2000 rpm at all loads. Furthermore, when analyzing CO2 emissions, with the exception of non-load conditions, the incorporation of GNPs resulted in an average rise of 3.10% in CO2 emissions at 1500rpm and 3.55% at 2000 rpm at all load conditions. The study revealed that fuel samples exhibited qualities close to those of diesel fuel standards.

STEPPING OUTSIDE THE BOX: TAILORING EXERCISE TEST PROTOCOLS & PROCEDURES

https://youtu.be/r8yQKiNeJWc INTRODUCTION The most frequently used exercise test protocol in the United States is the Bruce treadmill protocol. Using this standard protocol enables clinicians to report clinically useful information beyond myocardial ischemia, hemodynamic response, and rhythm, such as estimating prognosis with the Duke Treadmill Score and categorizing fitness by age and sex. However, some patients, especially highly fit aerobic-type athletes, might be better served with tailored exercise test procedures. CASE PRESENTATION A 22-year-old, apparently healthy male, collegiate track athlete complained of lightheadedness and profound fatigue after repeated intervals of 400-800 m. The referring physician ordered a cardiopulmonary exercise test in order to replicate his training regimen and symptoms. MANAGEMENT A plan was developed to perform a graded exercise test (GXT) on a treadmill with measurement of expired air, followed by a 3-min active cooldown, then up to 4 run/walk intervals of 1- and 2-min duration, respectively. Spirometry was performed before the GXT and repeatedly up to 20 min after the last run interval. The GXT protocol was based on the athlete’s self-reported pace during warmup (8:00/mile [4:58/km]) and a 10 km run (6:00/mile [3:44/km]) with a target duration of 10 min. The run intervals were based on his self-reported target time to complete 400 m (~65 s) during training. That time was converted to speed (13.8 miles/h [22.2 km/h]) and the associated metabolic equivalents of task (METs) were estimated (22 METs). Because the maximum speed of the laboratory treadmill is 12 miles/h (19.3 km/h), a 3% incline was used to achieve the target METs during the run intervals. A 12-lead ECG and pulse oximetry were monitored continuously during the GXT, the run/walk intervals, and through 6 min of recovery. Blood pressure (BP) was monitored via auscultation every 2 min through the initial 6 min of the GXT and recovery. BPs could not be obtained at higher running speeds. He did not use the handrail for support during testing. He reported that the run intervals were a similar level of exertion as during training. No abnormalities were noted during the GXT or the spirometry. His symptoms were reproduced during the 4th run interval. Total time in the laboratory was 1.5 hours. DISCUSSION Exercise testing on this patient could have been limited to a GXT (Bruce protocol or other), but the probability of reproducing his symptoms would have been low. As a young athlete, staff were confident that he could tolerate a GXT and several running intervals during the same encounter. Knowledge of METs allowed for an equivalent workload to be identified for the intervals despite limitations of the treadmill speed. It is not uncommon for laboratories to limit testing protocols to a few options (e.g. Bruce or modified Bruce). However, it can be beneficial to tailor procedures for select patients to increase the likelihood of reproducing patient-specific complaints or responses.

Intelligent consensus-based predictions of early life stage toxicity in fish tested in compliance with OECD Test Guideline 210.

Early life stage (ELS) toxicity testing in fish is a crucial test procedure used to evaluate the long-term effects of a wide range of chemicals, including pesticides, industrial chemicals, pharmaceuticals, and food additives. This test is particularly important for screening and prioritizing thousands of chemicals under the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation. In silico methods can be used to estimate the toxicity of a chemical when no experimental data is available and to reduce the cost, time, and resources involved in the experimentation process. In the present study, we developed predictive Quantitative Structure-Activity Relationship (QSAR) models to assess chronic effects of chemicals on ELS in fish. Toxicity data for ELS in fish was collected from two different sources, i.e. J-CHECK and eChemPortal, which contain robust study summaries of experimental studies performed according to OECD Test Guideline 210. The collected data included two types of endpoints - the No Observed Effect Concentration (NOEC) and the Lowest Observed Effect Concentration (LOEC), which were utilized to develop the QSAR models. Six different partial least squares (PLS) models with various descriptor combinations were created for both endpoints. These models were then employed for intelligent consensus-based prediction to enhance predictability for unknown chemicals. Among these models, the consensus model - 3 (Q2F1 = 0.71, Q2F2 = 0.71) and individual model - 3 (Q2F1 = 0.80, Q2F2 = 0.79) exhibited most promising results for both the NOEC and LOEC endpoints. Furthermore, these models were validated experimentally using experimental data from nine different industrial chemicals provided by Global Product Compliance (Europe) AB. Lastly, the models were used to screen and prioritize chemicals obtained from the Pesticide Properties (PPDB) and DrugBank databases.

Rapid diagnostic testing method to detect ROB β-lactamase gene in Neisseria meningitidis.

blaROB-1 is the only widely found β-lactamase in Neisseria meningitidis, and its presence is on the rise. To enhance our bacterial meningitis testing procedure, we clinically validated a real-time PCR assay to rapidly detect the blaROB gene and predict drug resistance in Neisseria meningitidis. A screen of 101 clinical isolates and 37 clinical specimens of blood and cerebrospinal fluid received between January 2018 and June 2024 found 8 isolates and 2 cerebrospinal fluid specimens that were positive for blaROB.

Performance Evaluation of Precast Pretensioned Hollow Core Slab Units by Loading Test

Strength evaluation of building components by analysis and in-place load testing is recommended in cases where the degree of suspected deficiencies in design, materials or construction cannot be readily determined. In the study, the purpose of the tests was to evaluate the performance of prestressed concrete hollow core slab (HCS) units carrying dead and live loads as composite members with topping concrete. The first test was conducted on HCS-300 panels, some of which were already installed in the buildings. A monotonic loading test on the ground at the construction site was performed on a non-composite panel to evaluate the actual composite panel's performance. In accordance with the project's quality procedures, to verify the performance of the HCS-400 panels, the second test was decided to be performed on HCS-400 composite panels in the precast plant prior to starting the mass production. The paper describes the application of monotonic loading test procedures and acceptance of test results according to the American ACI 318 standard.

Large-Scale Multiple Testing of Composite Null Hypotheses Under Heteroskedasticity

Abstract Heteroskedasticity poses several methodological challenges in designing valid and powerful procedures for simultaneous testing of composite null hypotheses. In particular, the conventional practice of standardizing or re-scaling heteroskedastic test statistics in this setting may severely affect the power of the underlying multiple testing procedure. Additionally, when the inferential parameter of interest is correlated with the variance of the test statistic, methods that ignore this dependence may fail to control the Type I error at the desired level. We propose a new heteroskedasticity adjusted multiple testing procedure that avoids data reduction by standardization, and directly incorporates the side information from the variances into the testing procedure. Our approach relies on an improved nonparametric empirical Bayes deconvolution estimator that offers a practical strategy for capturing the dependence between the inferential parameter of interest and the variance of the test statistic. We develop theory to show that the proposed procedure is asymptotically valid and optimal for FDR control. Simulation results demonstrate that our method outperforms existing procedures with substantial power gain across many settings at the same FDR level. The method is illustrated on an application involving the detection of engaged users on a mobile game app.