International Standard Test Research Articles

Performance of jute non-woven mat reinforced polyester matrix composite in multilayered armor

This paper presents results obtained through ballistic tests on multilayered armor system (MAS) using polyester composite reinforced with jute non-woven mat as second layer. Following international standard tests are carried out with ammunition 7.62×51mm, with a velocity above of 800m/s. The MAS is composed of a front layer with hexagonal ceramic tile (alumina doped with 4wt% of niobia), the second layer of polyester matrix composite reinforced with 30vol% of jute non-woven mat and the third layer an aluminum alloy plate. The utilization of polymeric composites reinforced with natural fibers to replace the aramid fabric (Kevlar™) is of interest because their performances are similar in the armor system but the composite is less expensive. Scanning electron microscopy analyses show that the polyester/jute non-woven mat composite captured ceramic fragments through mechanic incrustation. Moreover the replacement of aramid fabric for polyester matrix composites reinforced with jute non-woven mat provides weight reduction of the MAS by 5.4% and a cost reduction of 474%.

Entry qualifications of students as predictors of academic performance in various degree programs in distance education setting in Pakistan

Academic performance of students has always been the area of concern for educational institutions as it is a key indicator of institutional quality. In order to have a better quality output the higher education institutions set some admission criteria such as scores on specified international standardized tests, previous academic qualifications, and admission tests of students or a combination of such scores. Virtual University of Pakistan (VU) is a technology-based distance learning institution that facilitates students who are unable to attend traditional institutions of higher education for a variety of reasons. It was of interest to the researchers to study the entry qualifications of students i.e. the admission criteria, as predictor of their academic performance in various degree programs at VU. For that purpose, the data of 5825 graduates in different two years masters programs in 2015-16 were taken as sample. The entry qualifications of students, and cumulative scores of their previous academic qualifications were taken as predictors of their performance i.e. cumulative grade point average (CGPA,) in relevant degree program. Descriptive (range, percentage) and inferential (pearson r, multiple regression) statistics were applied after grouping the students into low, average and high achievers on cumulative scores as well as entry qualification scores. The results showed significant differences in the predictions and their implications are useful for policy makers and relevant departments of the university as well as for other distance learning educational institutions.

Strategic Processing of Chinese Young English Language Learners in an International Standardized English Language Test.

Strategic competence is acknowledged to be able to explain variations in language test performance. Research with adult language test-takers has shown that strategic competence has dual components: strategic knowledge and strategic processing. Of the two components, strategic processing, which is state-like, unstable, and tends to fluctuate from contexts to contexts, is more closely related to language test performance. To date, none of the existing studies investigates strategic processing with children English language learners (ELLs) and explores the relationship between strategic processing in all the four skills of language learning and the test performance. Addressing these gaps, the current study examined the nature of strategic processing in listening, reading and writing, and speaking of 138 Chinese young ELLs in an international standardized English language test – Cambridge Young Learners English Tests – Flyers test. The three questionnaires regarding strategic processing were administered to the participants immediately following the completion of the test. The confirmatory factor analyses verified that the strategic processing construct in the four skills comprised of a cognitive and a metacognitive dimensions, which resembles the strategic processing of the adult language test-takers. The participants adopted significantly more metacognitive than cognitive strategies consistently in the three sections of the test, possibly due to the status of the test. Both cognitive and metacognitive strategic processing were moderately related to the test performance, explaining from 7 to 31% of the variance in the total shields of the test. Across the four skills, high-performing test-takers used both cognitive and metacognitive strategies more frequently than the moderate- and low-performing test-takers, even though whether such differences were due to their richer strategic knowledge or processing skills was unknown. The study contributes to strategic processing in language testing literature and also provides practical implications for English trainers of the young ELLs in China.

Qualitative study of mechanical parameters of conventional diagnostic X-ray machines in Mizoram.

The present study examined the mechanical attributes of 135 conventional diagnostic X-ray machines in Mizoram, India. The purpose of studying the X-ray mechanical parameters, such as congruency, perpendicularity of the central beam, and half-value layer, was to improve the quality of the diagnostic image and reduce the patient dose. A battery-operated portable dosimeter was used to measure output radiation of the X-ray machine. The half-value layer was measured at a constant accelerating potential of 70 kVp and tube load. To measure the congruency and beam alignment perpendicularity, a congruence and alignment tool was used. The survey data were collected between June 2015 and June 2016. The authors followed international standard test procedures, and the results were compared to national and international standards. SPSS Statistics for Windows, Version 17 was used to calculate the mean, range, and standard deviation. The half-value layer ranged from 0.45 to 3.00mm; the mean half-value layer was 1.60 ± 0.51 SD mm. In comparison with national and international standards, only 27.83% (national) and 15.64% (international) of the machines' filtration were found to be within acceptable limits. The congruence misalignment of the x-axis varied between 0.50% and 15.30% of the source-to-image distance; for the y-axis, it ranged from 0.50 to 10.90%. When the congruence between the radiation beam and optical field was tested, 80.85% of diagnostic X-ray machines did not meet the prescribed acceptance parameters. When the perpendicularity between the central beam and the image receptor was tested, 69.81% did not meet safety standards.

Key parameters in testing biodegradation of bio-based materials in soil

Biodegradation of plastics in soil is currently tested by international standard testing methods (e.g. ISO 17556-12 or ASTM D5988-12). Although these testing methods have been developed for plastics, it has been shown in project KBBPPS that they can be extended also to lubricants with small modifications. Reproducibility is a critical issue regarding biodegradation tests in the laboratory. Among the main testing variables are the soil types and nutrients available (mainly nitrogen). For this reason, the effect of the soil type on the biodegradation rates of various bio-based materials (cellulose and lubricants) was tested for five different natural soil types (loam, loamy sand, clay, clay-loam, and silt-loam organic). It was shown that use of samples containing 1 g of C in a substrate of 300 g of soil with the addition of 0.1 g of N as nutrient strongly improves the reproducibility of the test making the results practically independent of the soil type with the exception of the organic soil. The sandy soil was found to need addition of higher amount of nutrients to exhibit similar biodegradation rates as those achieved with the other soil types. Therefore, natural soils can be used for Standard biodegradation tests of bio-based materials yielding reproducible results with the addition of appropriate nutrients.

Cirrhotic portal hypertension in the non-invasive era: what we grasp

The non-invasive era of portal hypertension in cirrhosis is approaching. We should seize the opportunity: then do learn to follow the recommended international guidelines for emerging non-invasive technologies and systematically utilize case resources of our country's for clinical verification; Secondly, we should pay attention to the cross-theory innovation of the middle level discipline in the process of technology development, and standardize the design and clinical registration in accordance with international diagnostic testing standards; Finally, a non-invasive technique for the treatment of cirrhotic portal hypertension was developed with a developmental perspective, enabling the transition from disease diagnosis and risk stratification to efficacy monitoring and prognosis prediction.

Grappling with translanguaging for teaching and assessment in culturally and linguistically diverse contexts: teacher perspectives from Oaxaca, Mexico

ABSTRACT Multilingual practices of translanguaging – fluid, complex, and dynamic processes of using one's complete linguistic repertoire – have been increasingly embraced by researchers and educators in bilingual education. Applying this perspective within the field of assessment has proven more challenging. In this project, we explore the role of multilingualism in teaching and classroom assessment design and practice, drawing upon the concept of translanguaging as a lens through which to explore the perceptions and practices of teachers. Working from assumptions that multilingualism in classrooms is an important tool to enhance the learning of linguistic minority students, we examined how teachers perceive and practice translanguaging in classroom language assessments through an action research case study with 40 language teachers in the linguistically and culturally diverse state of Oaxaca, Mexico. Their reflections ranged from the pressure to train students to produce monolingual-like language in order to pass international standardized tests to the potential to validate students’ linguistic repertoires and multicultural identities through increased use of translanguaging. Our analysis of this action research study and discussion of the potentials and limitations of translanguaging in teaching and assessments aims to contribute to the development of more equitable and effective multilingual education environments in the future.

Thermal characterization of full-scale PCM products and numerical simulations, including hysteresis, to evaluate energy impacts in an envelope application

This article presents combined measurements of fatty acid-based organic PCM products and numerical simulations to evaluate the energy benefits of adding a PCM layer to an exterior wall. The thermal storage characteristics of the PCM were measured using a heat flow meter apparatus (HFMA). The PCM characterization is based on a recent ASTM International standard test method, ASTM C1784. The PCM samples were subjected to step changes in temperature and allowed to stabilize at each temperature. By measuring the heat absorbed or released by the PCM, the temperature-dependent enthalpy functions for melting and freezing were determined.The simulations were done using a previously-validated two-dimensional (2D) wall model containing a PCM layer and incorporating the HFMA-measured enthalpy functions. The wall model was modified to include the hysteresis phenomenon observed in PCMs, which is reflected in different melting and freezing temperatures of the PCM. Simulations were done with a single enthalpy curve based on the PCM melting tests, both melting and freezing enthalpy curves, and with different degrees of hysteresis between the melting and freezing curves. Significant differences were observed between the thermal performances of the modeled wall with the PCM layer under the different scenarios.

It's Good To Go Backwards—Sometimes

Large, solid pole synchronous motors are in common use today across many industries and applications. International testing standards are well known by manufacturers and users alike. However, no current standard specifies testing methods to simulate the heat generated during asynchronous starting. The energy absorbed and the heat generated is significant and may produce surface temperatures that exceed 400 °C. This heat produces differential expansion between different materials as well as within the depth of the pole itself. The full impact of this effect is not known until the motor meets the driven equipment (and electrical system) at site, i.e., the first coupled start. A test method has been developed that ensures motors can be tested in the factory with the same energy being absorbed as at site. This gives the user (and motor manufacturer) far greater confidence in the design and avoids any unexpected “surprises” that may occur during the first or subsequent starts at site.

Design and Development of a Test Method for Analyzing Protective Performance of Gloves Exposed to Radiant Heat Based on Computational Fluid Dynamics Analysis

ABSTRACTGloves are one of the most important items in the protective ensemble as they protect hand which is the most frequently burned body part. At present, no international standard or standardized test method is available for analyzing thermal protective performance of gloves exposed to purely radiant heat exposures. In the present work, a systematic approach for developing test setup for radiant heat exposure is proposed using computational fluid dynamics (CFD). A coupled CFD–radiation heat transfer model is first developed and validated with available experimental data. Effects of horizontal and vertical orientations of radiant heaters are then analyzed. Based on this study, an optimized configuration of the experimental setup which results in uniform heat flux distribution throughout the hand under lower level of radiant heat exposure is proposed. Furthermore, effects of different heater temperatures on heat flux distribution are studied. It is found that the proposed configuration works satisfactorily for other higher and lower heat flux levels as well.

Vibration and shock analysis of specific events during truck and train transport of food products

Abstract In international test standards and literature averaged vibration spectra of truck and train transports are reported. However, cargo is exposed to extreme levels of vibrations and shocks for which the averaged vibration data are not representative. The objective of this study is to report evidence of the extreme vibrations and shocks during truck and train transport, and help food scientists design relevant vibration and shock simulation experiments. Results indicate that trains and trucks experience transient phenomena when traveling over train switches, accelerating and stopping the train, respectively road unevenness (e.g. potholes). The damping ratio (β) of shocks measured on the railcar is on average 0.05 ± 0.02, while on the truck 0.08 ± 0.02. Furthermore, the measured spectra of this study diverge from the spectra of international standards. A time-domain analysis indicates that traveling over cobblestones, and concrete pavement generates the most severe vibrations and shocks (dependency on truck velocity).

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during an impact are important factors in protecting the helmet wearer from impact-induced injury. This manuscript aims to investigate impact-induced injury mechanisms in different helmet fit scenarios through analysis of simulated helmeted impacts with an anthropometric test device (ATD), an array of headform acceleration transducers and neck force/moment transducers, a dual high speed camera system, and helmet-fit force sensors developed in our research group based on Bragg gratings in optical fiber. To simulate impacts, an instrumented headform and flexible neck fall along a linear guide rail onto an anvil. The test bed allows simulation of head impact at speeds up to 8.3 m/s, onto impact surfaces that are both flat and angled. The headform is fit with a crash helmet and several fit scenarios can be simulated by making context specific adjustments to the helmet position index and/or helmet size. To quantify helmet retention, the movement of the helmet on the head is quantified using post-hoc image analysis. To quantify head and neck injury potential, biomechanical measures based on headform acceleration and neck force/moment are measured. These biomechanical measures, through comparison with established human tolerance curves, can estimate the risk of severe life threatening and/or mild diffuse brain injury and osteoligamentous neck injury. To our knowledge, the presented test-bed is the first developed specifically to assess biomechanical effects on head and neck injury relative to helmet fit and retention.

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact.

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during an impact are important factors in protecting the helmet wearer from impact-induced injury. This manuscript aims to investigate impact-induced injury mechanisms in different helmet fit scenarios through analysis of simulated helmeted impacts with an anthropometric test device (ATD), an array of headform acceleration transducers and neck force/moment transducers, a dual high speed camera system, and helmet-fit force sensors developed in our research group based on Bragg gratings in optical fiber. To simulate impacts, an instrumented headform and flexible neck fall along a linear guide rail onto an anvil. The test bed allows simulation of head impact at speeds up to 8.3 m/s, onto impact surfaces that are both flat and angled. The headform is fit with a crash helmet and several fit scenarios can be simulated by making context specific adjustments to the helmet position index and/or helmet size. To quantify helmet retention, the movement of the helmet on the head is quantified using post-hoc image analysis. To quantify head and neck injury potential, biomechanical measures based on headform acceleration and neck force/moment are measured. These biomechanical measures, through comparison with established human tolerance curves, can estimate the risk of severe life threatening and/or mild diffuse brain injury and osteoligamentous neck injury. To our knowledge, the presented test-bed is the first developed specifically to assess biomechanical effects on head and neck injury relative to helmet fit and retention.

Experimental and theoretical investigation on the role of friction in Nakazima testing

The Nakazima test is a commonly used method to experimentally measure the forming limit curve (FLC) of sheet metal. Various researchers have different opinions about the effect of tribological conditions at the interface of the punch and specimen in Nakazima testing, such that international industry test standards specify conflicting requirements to address friction conditions during testing. This paper provides analysis to resolve this conflict and demonstrates the effectiveness of an analytical procedure to account for and eliminate effects of friction in determination of the strain FLC as a material property that is independent of friction. With the aid of digital image correlation (DIC) techniques, Nakazima tests of a dual phase steel (DP980) were performed under two clearly different friction conditions: (1) friction was minimized between the punch and the specimen by conducting tests using a thin Teflon sheet, and (2) friction was maximized by conducting tests without any lubricant after chemically cleaning the punch and sheet surfaces. As expected, the strain FLCs obtained under these two friction conditions are different. However, analysis shows that the strain path at material points within the same test specimen are the same for both friction conditions. The only difference observed is that the relative strain rates at different material points are strongly affected by friction, which causes necking and fracture to initiate at different locations on test specimens. Furthermore, by accounting for the effects of local strain path, curvature, and contact pressure on the measured strain history at the location of necking using the method described by Min et al. [27], the corrected strain FLCs obtained under very low and very high friction conditions are shown to be indistinguishable.

An SOE estimation model considering electrothermal effect for LiFePO4/C battery

The state of energy (SOE) is an important performance parameter and evaluation index for LiFePO4/C battery since the available energy can be known more intuitively through SOE compared with state of charge (SOC). First, in order to improve the estimation accuracy of SOE, a novel estimation model combining electrical energy and thermal energy is put forward by studying the effects of discharge rate to the change laws of all kinds of energy inside the battery cell. Moreover, the concepts of unavailable energy Eu, maximum allowable energy E, and discharge energy efficiency η are originally proposed based on the analysis of energy consumption. Second, the parameter of actual maximum energy and energy consumption revised by the case of LiFePO4/C battery can give an example to show the specific steps for improving the estimation accuracy of SOE during any integration time by using the novel SOE estimation model. Lastly, 2 international standard test experiments of EV are conducted to show the correction of SOC can efficiently limit the error below 4.6% and also indicate the novel SOE estimation method suitable for application area.

Comparative Analysis of Motorcycle Braking Performance in Emergency Situation

This study was conducted to assess motorcycle braking performance in simulated emergency situation. Braking distances and G- force values (peak) during the braking test of 6 distinct underbone motorcycles of 100-150cc were measured and compared based on different test conditions namely type of brake system (disc and drum), method of braking operation (front and rear brakes) and test load (rider only and rider with pillion). The results indicate that type of braking system and method of braking operation significantly influenced braking distance and G-force value. However, test load was found insignificant. The shortest braking distance and highest deceleration rate were 12.48 meters and 8.52 m/s2, respectively. The lowest G-force value (peak) was recorded 0.39 throughout the test. It is to be noted that this study is unique on its own due to certain limitations although some of the methods were adopted from the established international braking test standards. Even though this study is considered fundamental, the findings could provide vital information on the braking performance of underbone motorcycles especially to the motorcycle manufacturers and OEMs, as well as to the relevant authorities (driving institutes and Road Transport Department).

A laser-aided direct metal tooling technology for artificial joint surface coating

Longevity of cementless arthroplasty is determined by the characteristics of the porous structure formed at the surface. However, currently used artificial joint surface coating technologies have several limitations. Therefore, the goal of this study was to investigate the use of an artificial surface coating technology to overcome the limitations of currently used technologies. An artificial joint surface coating that controls porosity of the porous structure formed at the surface of the artificial joint was developed based on laser-aided direct metal tooling (DMT) technology, which is a three-dimensional (3-D) additive manufacturing (AM) technology. The structural, mechanical, and physical properties of the DMT surface coating was measured in accordance with the international testing standards and compared to titanium plasma spray (TPS) surface coating, a commercially available artificial joint surface coating. DMT exhibited characteristics comparable, if not better, than the existing commercial TPS in terms of mechanical and physical properties. DMT may be useful for cementless artificial joint surface coating required the porosity control of the porous structure formed at the surface of the artificial joint and provides enhanced longevity and patient prognosis compared to the existing surface coating technologies.

Examining the Usefulness of ISO 10819 Anti-Vibration Glove Certification.

Anti-vibration gloves are commonly worn to reduce hand-arm vibration exposure from work with hand-held vibrating tools when higher priority and more effective controls are unavailable. For gloves to be marketed as 'anti-vibration' they must meet the vibration transmissibility criteria described in the International Organization for Standardization (ISO) standard 10819 (2013). Several issues exist with respect to the methodology used for glove testing as well as the requirements for glove design and composition in ISO 10819 (2013). The true usefulness of anti-vibration gloves at preventing hand-arm vibration syndrome (HAVS) is controversial, given that their performance is dependent on tool vibration characteristics and the anthropometrics of workers in real working conditions. The major risk associated with the use of anti-vibration gloves is that it will give employees and employers a false sense of protection against the negative effects of hand-transmitted vibration. This commentary examines the limitations of the current international standards for anti-vibration glove testing and certification, thereby calling into question the degree of protection that anti-vibration gloves provide against HAVS, and cautioning users to consider both their benefits and potential drawbacks on a case-by-case basis.

天然气中H<sub>2</sub>S快速定量检测研究进展

H2S对天然气的运输、贮存及使用安全会产生破坏性的影响，其含量是天然气检测必不可少的项目，快速准确测定其含量具有极其重要的意义。本文对天然气中H2S检测所用到的国内国际标准进行了总结分析。在此基础上，综述了满足快速定量检测H2S的半导体氧化物、电化学和光学传感器研究进展，比较各种H2S检测传感器的操作标准(如操作原理、检测限、响应时间、检测浓度范围)。最后，探讨各种传感器的不足并指出今后的发展方向。 H2S has great effect on the transportation, storage and use safety of natural gas. It is an absolutely necessary measuring project for natural gas quality control. So it has important significance to quickly and precisely monitor H2S content. The summary is made about the present national and international standard test method for H2S in natural gas. Based on these, sensor-based type for quantifying H2S including semiconductor metal oxide, electrochemical and optical sensor are re-viewed. Different quality-assurance parameters (e.g., operating principles, limit of detection, re-sponse time and common operating range of concentration) are evaluated and compared. Finally, the limitations and the future prospects of these sensor-based methods are highlighted.

A study on quantitative analysis of the relationship between camera image characteristics and operability of rescue robots

Many rescue robots have been developed that are teleoperated using images from a camera mounted on the robots. This study examined how the conditions of the images from the camera affect the operability of a rescue robot used for a search task in a 2D maze. Two experiments with subject were performed using a robot simulator USARSim, whereby the first one was a preliminary experiment. As a first, this study compares 100 combinations of the position and posture of a camera mounted on a robot. In the second experiment, 16 images with various indices were used in the main experiment. The indices xmin and h use the images captured by the camera to provide information relating to the robot and the environment around the robot, respectively. These were defined from the results of the preliminary experiment. The tasks performed and scoring method used for the experiments were determined by referring to the DHS-NIST-ASTM International Standard Test Methods for Rescue Robots. The results of the main experiment showed that the operability of the robot has an extreme value when the indices (xmin, h) were (100, 3,000).