A Simple Device for Assessing Wrinkle Performance of Fabrics by Stress Relaxation in Bending

1976 ◽  
Vol 46 (7) ◽  
pp. 525-529 ◽  
Author(s):  
B. M. Chapman
Keyword(s):  
Stress Relaxation ◽  
Relative Humidity ◽  
Test Procedure ◽  
Simple Device ◽  
Test Display ◽  
Coefficients Of Variation ◽  
Wide Range ◽  
Routine Assessment

A simple device for measuring stress relaxation of fabrics in bending is described. It may be used to obtain the viscoelastic and frictional components V and F, which have been shown to determine the recovery of fabrics from bending deformations. A test procedure of relevance to the practical wrinkling situation is suggested and involves the measurement of stress relaxation during a chance in relative humidity. A series of fabrics subjected to this test display a wide range of V and F values exhibiting low coefficients of variation between readings. The instrument should prove useful for analytical or routine assessment of the wrinkling behavior of fabrics.

scholarly journals Development and Validation of 2-Azaspiro [4,5] Decan-3-One (Impurity A) in Gabapentin Determination Method Using qNMR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1656
Author(s):  
Nataliya E. Kuz’mina ◽  
Sergey V. Moiseev ◽  
Mikhail D. Khorolskiy ◽  
Anna I. Lutceva
Keyword(s):  
Test Procedure ◽  
Active Pharmaceutical Ingredient ◽  
Test Methods ◽  
Intermediate Precision ◽  
Coefficients Of Variation ◽  
Validation Parameters ◽  
Limit Of Quantitation ◽  
Student’S T ◽  
Development And Validation ◽  
Student’S T Test

The authors developed a 1H qNMR test procedure for identification and quantification of impurity A present in gabapentin active pharmaceutical ingredient (API) and gabapentin products. The validation studies helped to determine the limit of quantitation and assess linearity, accuracy, repeatability, intermediate precision, specificity, and robustness of the procedure. Spike-and-recovery assays were used to calculate standard deviations, coefficients of variation, confidence intervals, bias, Fisher’s F test, and Student’s t-test for assay results. The obtained statistical values satisfy the acceptance criteria for the validation parameters. The authors compared the results of impurity A quantification in gabapentin APIs and capsules by using the 1H qNMR and HPLC test methods.

scholarly journals Developing Relative Humidity and Temperature Corrections for Low-Cost Sensors Using Machine Learning

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3338
Author(s):  
Ivan Vajs ◽  
Dejan Drajic ◽  
Nenad Gligoric ◽  
Ilija Radovanovic ◽  
Ivan Popovic
Keyword(s):  
Machine Learning ◽  
Air Quality ◽  
Relative Humidity ◽  
Low Cost ◽  
Quality Monitoring ◽  
Air Quality Monitoring ◽  
Lower Accuracy ◽  
Wide Range ◽  
The Impact ◽  
Monitoring Stations

Existing government air quality monitoring networks consist of static measurement stations, which are highly reliable and accurately measure a wide range of air pollutants, but they are very large, expensive and require significant amounts of maintenance. As a promising solution, low-cost sensors are being introduced as complementary, air quality monitoring stations. These sensors are, however, not reliable due to the lower accuracy, short life cycle and corresponding calibration issues. Recent studies have shown that low-cost sensors are affected by relative humidity and temperature. In this paper, we explore methods to additionally improve the calibration algorithms with the aim to increase the measurement accuracy considering the impact of temperature and humidity on the readings, by using machine learning. A detailed comparative analysis of linear regression, artificial neural network and random forest algorithms are presented, analyzing their performance on the measurements of CO, NO2 and PM10 particles, with promising results and an achieved R2 of 0.93–0.97, 0.82–0.94 and 0.73–0.89 dependent on the observed period of the year, respectively, for each pollutant. A comprehensive analysis and recommendations on how low-cost sensors could be used as complementary monitoring stations to the reference ones, to increase spatial and temporal measurement resolution, is provided.

The State of the Art of Rubber-Seal Technology

1987 ◽  
Vol 60 (3) ◽  
pp. 381-416 ◽  
Author(s):  
B. S. Nau
Keyword(s):  
State Of The Art ◽  
Test Procedure ◽  
Working Party ◽  
The State ◽  
Supporting Evidence ◽  
Wide Range ◽  
Lip Seals ◽  
Alternative Hypotheses ◽  
Series Of Experiments ◽  
Range Of Values

Abstract The understanding of the engineering fundamentals of rubber seals of all the various types has been developing gradually over the past two or three decades, but there is still much to understand, Tables V–VII summarize the state of the art. In the case of rubber-based gaskets, the field of high-temperature applications has scarcely been touched, although there are plans to initiate work in this area both in the U.S.A. at PVRC, and in the U.K., at BHRA. In the case of reciprocating rubber seals, a broad basis of theory and experiment has been developed, yet it still is not possible to design such a seal from first principles. Indeed, in a comparative series of experiments run recently on seals from a single batch, tested in different laboratories round the world to the same test procedure, under the aegis of an ISO working party, a very wide range of values was reported for leakage and friction. The explanation for this has still to be ascertained. In the case of rotary lip seals, theories and supporting evidence have been brought forward to support alternative hypotheses for lubrication and sealing mechanisms. None can be said to have become generally accepted, and it remains to crystallize a unified theory.

A simple device to apply equibiaxial strain to cells cultured on flexible membranes

2008 ◽  
Vol 294 (1) ◽  
pp. H532-H540 ◽  
Author(s):  
Obaida R. Rana ◽  
Carsten Zobel ◽  
Esra Saygili ◽  
Klara Brixius ◽  
Felix Gramley ◽  
...  
Keyword(s):  
Cell Biology ◽  
Low Cost ◽  
Normal Growth ◽  
Neonatal Rat ◽  
Simple Device ◽  
Static Stretch ◽  
Voltage Gated ◽  
Wide Range ◽  
Dose Dependent ◽  
Cells Cultured

The biomechanical environment to which cells are exposed is important to their normal growth, development, interaction, and function. Accordingly, there has been much interest in studying the role of biomechanical forces in cell biology and pathophysiology. This has led to the introduction and even commercialization of many experimental devices. Many of the early devices were limited by the heterogeneity of deformation of cells cultivated in different locations of the culture plate membranes and were also attached with complicated technical/electronic efforts resulting in a restriction of the reproducibility of these devices. The objective of this study was to design and build a simple device to allow the application of dose-dependent homogeneous equibiaxial static stretch to cells cultured on flexible silicone membranes to investigate biological and biomedical questions. In addition, cultured neonatal rat atrial cardiomyocytes were stretched with the proposed device with different strain gradients. For the first time with this study we could demonstrate that stretch up to 21% caused dose-dependent changes in biological markers such as the calcineurin activity, modulatory calcineurin-interacting protein-1, voltage-gated potassium channel isoform 4.2, and voltage-gated K+ channel-interacting proteins-2 gene expression and transient outward potassium current densities but not the protein-to-DNA ratio and atrial natriuretic peptide mRNA. With both markers mentioned last, dose-dependent stretch alterations could only be achieved with stretch up to 13%. The simple and low-cost device presented here might be applied to a wide range of experimental settings in different fields of research.

scholarly journals Cross-Linker Control of Vitrimer Flow

2020 ◽  
Author(s):  
Bassil El-Zaatari ◽  
Jacob Ishibashi ◽  
Julia Kalow
Keyword(s):  
Stress Relaxation ◽  
Elevated Temperatures ◽  
Bulk Material ◽  
Relaxation Rates ◽  
Exchange Reactions ◽  
Activation Barriers ◽  
Flow Activation Energy ◽  
Wide Range ◽  
Cross Linker ◽  
Frequency Sweeps

<div><p>Vitrimers are a class of covalent adaptable networks (CANs) that undergo topology reconfiguration via associative exchange reactions, enabling reprocessing at elevated temperatures. Here, we show that cross-linker reactivity represents an additional design parameter to tune stress relaxation rates in vitrimers. Guided by calculated activation barriers, we prepared a series of cross-linkers with varying reactivity for the conjugate addition—elimination of thiols in a PDMS vitrimer. Surprisingly, despite a wide range of stress relaxation rates, we observe that the flow activation energy of the bulk material is independent of the cross-linker structure. Superposition of storage and loss moduli from frequency sweeps can be performed for different cross-linkers, indicating the same exchange mechanism. We show that we can mix different cross-linkers in a single material in order to further modulate the stress relaxation behavior.</p></div>

Development of a Constitutive Backstress Model for the Prediction of Creep and Stress Relaxation in Gas Turbine Materials

2020 ◽  
Author(s):  
Andrew Moffat ◽  
Richard Green ◽  
Calum Ferguson ◽  
Brent Scaletta
Keyword(s):  
Stress Relaxation ◽  
Creep Deformation ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Creep Model ◽  
Effect Of Temperature ◽  
Deformation Model ◽  
Corrosion Resistant ◽  
Single Temperature ◽  
Wide Range

Abstract There is a drive towards a broader range of fuels in industrial gas turbines, with higher levels of sulphur and potentially hydrogen. Due to these harsher environments, there is also a drive for corrosion resistant alloys and coatings. A number of key corrosion resistant superalloys, which are being employed to cope with these evolving conditions, exhibit primary creep. It is therefore imperative that fundamental material models, such as those for creep deformation, are developed to ensure they can accurately predict the material response to evolving operating conditions. The requirements for a creep model are complex. The model must be able to: predict forward creep deformation in regions dominated by primary loads (such as pressure); predict stress relaxation in regions dominated by secondary loads (such as differential thermal expansion); predict the effects of different creep hardening mechanisms. It is also clear that there is an interaction between fatigue and creep. With flexible operation, this interaction can be significant and should be catered for in lifing methods. A model that has the potential to account for the effect of plasticity on creep, and creep on plasticity is therefore desirable. In previous work the authors presented the concept for a backstress model to predict creep strain rates in superalloys. This model was fitted to a limited dataset at a single temperature. The approach was validated using simple creep-dwell tests at the same temperature. This paper expands on the previous work in several ways: 1) The creep model has been fitted over a wide range of temperatures. Including the effect of temperature in complex creep models presents a number of difficulties in model fitting and these are explored. 2) The model was fitted to constant load (forward creep) and constant strain (stress relaxation) tests since any creep model should be able to predict both forms of creep deformation. However, these are often considered separately due to the difficulty of fitting models to two different datasets. 3) The creep deformation model was validated on stress change tests to ensure the creep deformation response can cope with changes in response variables. 4) The approach was validated using creep-fatigue tests to show that the creep deformation model, in addition to our established fatigue models, can predict damage in materials under complex loading.

The null-hypothesis significance-test procedure is still warranted

1998 ◽  
Vol 21 (2) ◽  
pp. 228-235 ◽  
Author(s):  
Siu L. Chow
Keyword(s):  
Null Hypothesis ◽  
Statistical Power ◽  
Meta Analysis ◽  
Statistical Significance ◽  
Test Procedure ◽  
Significance Test ◽  
Null Hypothesis Significance Test ◽  
Wide Range ◽  
Statistical Hypotheses ◽  
Alternative Hypotheses

Entertaining diverse assumptions about empirical research, commentators give a wide range of verdicts on the NHSTP defence in Statistical significance. The null-hypothesis significance-test procedure (NHSTP) is defended in a framework in which deductive and inductive rules are deployed in theory corroboration in the spirit of Popper's Conjectures and refutations (1968b). The defensible hypothetico-deductive structure of the framework is used to make explicit the distinctions between (1) substantive and statistical hypotheses, (2) statistical alternative and conceptual alternative hypotheses, and (3) making statistical decisions and drawing theoretical conclusions. These distinctions make it easier to show that (1) H0 can be true, (2) the effect size is irrelevant to theory corroboration, and (3) “strong” hypotheses make no difference to NHSTP. Reservations about statistical power, meta-analysis, and the Bayesian approach are still warranted.

scholarly journals Variability Associated with Testing Shelled Corn for Fumonisin

1998 ◽  
Vol 81 (6) ◽  
pp. 1162-1168 ◽  
Author(s):  
Thomas B Whitaker ◽  
Mary W Trucksess ◽  
Anders S Johansson ◽  
Francis G Geesbrecht ◽  
Winston M Hagler ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Sample Preparation ◽  
Coefficient Of Variation ◽  
Variance Component ◽  
Test Procedure ◽  
Functional Relationships ◽  
Similar Test ◽  
Coefficients Of Variation ◽  
Order Of Magnitude

Abstract Variances associated with sampling, sample preparation, and analytical steps of a test procedure that measures fumonisin in shelled corn were estimated. The variance associated with each step of the test procedure increases with fumonisin concentration. Functional relationships between variance and fumonisin concentration were estimated by regression analysis. For each variance component, functional relationships were independent of fumonisin type (total, B1, B2, and B3 fumonisins). At 2 ppm, coefficients of variation associated with sampling (1.1 kg sample), sample preparation (Romer mill and 25 g subsample), and analysis are 16.6,9.1, and 9.7%, respectively. The coefficient of variation associated with the total fumonisin test procedure was 45% and is about the same order of magnitude as that for measuring aflatoxin in shelled corn with a similar test procedure.

scholarly journals Responses to climatic factors by foragers of Plebeia pugnax Moure (in litt.) (Apidae, Meliponinae)

2001 ◽  
Vol 61 (2) ◽  
pp. 191-196 ◽  
Author(s):  
S. D. HILÁRIO ◽  
V. L. IMPERATRIZ-FONSECA ◽  
A. de M. P. KLEINERT
Keyword(s):  
Relative Humidity ◽  
Light Intensity ◽  
Minimum Temperature ◽  
Climatic Factors ◽  
Flight Activity ◽  
Wide Range ◽  
The Hours ◽  
Recorded Data

Flight activity of Plebeia pugnax Moure (in litt.) was studied in six colonies coming from Cunha, SP, from July to October 1994. Twice a week, from 8:00 a.m. to 6:00 p.m., for 5 minutes every half-hour, all the bees entering and leaving the hives were counted. Six hundred counts were made and the materials that foragers carried were recorded. Data were analysed in relation to temperature, relative humidity, light intensity and day time. Foragers' flight activity was relatively constant in a wide range of temperature, from 22°C to 34°C. The minimum temperature for the beginning of flight activity was 14°C. Effective flight activity (when foragers of all colonies were leaving the hives) occurred at 15°C. These bees also flew within a wide range of relative humidity, from 30% to 100%, decreasing slowly after 50%. Flight activity increased as light intensity rose and it has also increased as the hours passed by, reaching a peak around midday and decreasing gradually afterwards. Pollen was collected all day long, while resin collection was relatively constant and debris transportation was slightly higher after 10:00 h. From all known Plebeia species, this one flew on the lowest temperature ever registered for this genus.

A Simple Device for Integrating Temperature, Relative Humidity or Salinity over Time

1986 ◽  
Vol 3 (1) ◽  
pp. 186-190 ◽  
Author(s):  
Fred W. Trembour ◽  
Irving Freidman ◽  
F. Joseph Jurceka ◽  
Franklin L. Smith
Keyword(s):  
Relative Humidity ◽  
Simple Device ◽  
Over Time
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