ANALYSIS OF THE TRAFFIC LOAD–INDUCED STRESSES OF EMBANKMENT

This article represents traffic loads on the road structure distribution and evaluation of the vertical and horizontal stresses formation in the soil embankment. This evaluation allows to predict the depth and intensity of the propagation of additional stresses resulting from traffic loads. The calculations were performed in accordance with four normative documents applied in Lithuania, which define the loads on the road structure. The obtained results showed that the area to which the load is distributed has the greatest influence on the intensity of stresses and the distance of propagation. The maximum horizontal stress in the embankment was found to be no more than 70 kPa and the maximum stress propagation depth did not exceed 0.9 m. The results can be applied to a triaxial test apparatus to restore horizontal stresses in the embankment. It is recommended to select a lateral pressure from 20 kPa to 70 kPa for tests provided with triaxial test device. The mechanical properties of the soil determined with triaxial test device and recommended lateral pressure would be representative of the test results obtained in the field of embankment.

Validation of the local applicability of the ‘TIB’ Olfactory Test Device in the era of COVID-19

Objective To evaluate the validity and test–retest reliability of the novel ‘TIB’ Olfactory Test Device (TIB) and to determine its normative values. Methods The study stratified the study subjects into normosmic, hyposmic and anosmic groups according to their olfactory function. The olfactory function of the subjects was evaluated using both the traditional Chinese version of the University of Pennsylvania of Smell Identification Test (UPSIT-TC) and the TIB. The normosmic group was used to retest with the UPSIT-TC and TIB at an inter-test interval of at least 7 days. The cut-off scores of TIB among the three different groups were determined by receiver operating characteristic curve analysis. Results This study enrolled 180 subjects: 60 in each group. The mean scores of TIB were 44.1 for the normosmic group, 27.5 for the hyposmic group and 10.9 for the anosmic group. The TIB scores were significantly different across the three groups. There was a significant correlation between the first and second TIB tests ( r = 0.506). The cut-off scores were 41 for normosmic subjects and 24 for hyposmic subjects. Conclusion The validity and test–retest reliability results suggest that the TIB is an appropriate olfactory test for the Taiwanese population.

DESIGN AND EXPERIMENT OF CENTRIFUGAL COLLISION TEST DEVICE FOR MILLET AND SWEET BUCKWHEAT GRAIN

This critical collision damage force of millet and sweet buckwheat grain and the shelling force of shelled granular materials are important basic data for research of threshing and shelling technology and equipment. In order to master the linear velocity and collision force of grain with different moisture content when collision damage occurs, a centrifugal collision test device is designed. Based on the dynamic and kinematic analysis of grain in the centrifugal rotary table, the collision force between grain and steel plate was measured by PVDF piezoelectric pressure sensor and data acquisition system. The results showed that: under the same moisture content, the higher the rotational speed, the higher the grain crushing rate; at the same rotational speed, with the increase of moisture content, the crushing rate first decreased and then increased. When the moisture content of Jingu-21 and Yuqiao-4 is 19.7% and 17.8%, respectively, the grain crushing rate was the lowest. In terms of the anti-collision ability of grain, the optimum moisture content of threshing is between 19.7% and 21% for millet. For sweet buckwheat, the optimum moisture content of threshing is 17.8% ~19%, while the optimum moisture content of shelling by centrifugal sheller is about 11%. The faster the rotational speed of centrifugal rotary table is, the greater the linear speed of grain is, and the greater the collision force is. When the linear velocity of grain was 8.32 m/s and 11.30 m/s respectively, the millet grain moisture content was 11.1% and 20.9% respectively, damage began to appear, and the corresponding collision force was about 5.51 N and 10.6 N, respectively. When the linear velocity of grain was 8.32 m/s and 11.30m/s respectively, and the moisture content was 11.1% and 22.8% of the sweet buckwheat grain respectively, damage began to appear, the corresponding collision force was about 8.92 N and 12.79 N, respectively. When the rotating speed of rotary table was 910 r/min, the linear speed of grain was 27.05 m/s, the crushing rate of millet and sweet buckwheat grain in harvest period were 56.30% and 63.76%, respectively, and the crushing rate of millet and buckwheat grain with 11.1% moisture content were 86.27% and 89.4%, respectively. The research results can provide theoretical basis for design and optimization of millet and sweet buckwheat combine harvester, threshing device and shelling device.

Apparatus and Method for Strain Energy Based Resiliency Measurement of Loss Control Materials

Loss of circulation is one of the greatest challenges that are frequently encountered while drilling. Various types of LCM products are used by the industry to combat loss of circulation. Characterization of these LCM products is very important to select the most suitable products to improve the success rate of LCM treatment jobs. This paper describes the theoretical basis of the application of strain energy along with the development of a strain energy-based mathematical model to create a dedicated software driven novel method and test apparatus for quick and reliable measurement of the coefficient of resiliency of various LCM products to improve the likelihood and probability of success rate of LCM treatment jobs. The simple but reliable method and apparatus provide a fit-for-purpose solution for additional characterization of LCM products. The design and construction of the test device and the development of the method considered the most critical technical factors that have high impact on data reliability, data accuracy, repeatability and data sensitivity. The components of the test device were selected based on technical, economical, portability and ease of operation using a dedicated software driven method and data acquisition system. Experimental results generated by loading and unloading a particular mass of a LCM product under a constant displacement rate of the loading foot of the test apparatus demonstrated the suitability of the method and the apparatus in determining the coefficient of resiliency of LCM products. Based on the area below the loading curve i.e. the strain energy absorbed during the loading cycle and the area below the unloading curve i.e. the strain energy desorbed during the unloading cycle, the data acquisition software automatically calculates the coefficient of resiliency of the LCM products. The resilient characteristic of LCM products is one of the critical factors that is very important for high performance pill or slurry design to enhance the seal/plug stability. Hence, the newly developed method and apparatus will play a positive role to improve the probability and the likelihood of creating a stable and lasting seal/plug in the loss zones. As loss control materials with good resilient properties are highly adaptable in changing stress and pressure conditions, this method can provide appropriate guidelines to mud chemists, mud engineers and mud consultants in designing high performance LCM blends or slurries to combat moderate and severe loss of circulation.

Laboratory assessment of a head impact sensor for youth soccer ball heading impacts using an anthropomorphic test device

Recent advances in technology have enabled the development of instrumented equipment, which estimate the head impact kinematics of athletes in vivo. One such headband-mounted impact sensor is the SIM-G (Triax Technologies, Norwalk, CT, USA), which has been previously used to investigate the biomechanics of soccer heading by human subjects. Previous studies have evaluated the accuracy of the SIM-G for pure rotation and pendulum, impulse hammer and drop rig impacts. The current study used a soccer ball heading model to evaluate the accuracy of the SIM-G. A soccer ball was projected at the head of an anthropomorphic test device (ATD) representing a 10-year-old to replicate the heading maneuver at various impact sites, angles and speeds previously identified in youth soccer. Linear regression revealed that the SIM-G sensor overestimated the peak angular velocity and linear acceleration recorded by the ATD headform by approximately 44% and 105%, respectively. Tests in which the ball directly contacted the SIM-G sensor resulted in the largest peak linear accelerations. Glancing impacts were significantly associated with a decrease in percentage error of the SIM-G sensor peak angular velocity data relative to the ATD reference data. While it may not demonstrate accuracy in estimating the magnitudes of head impacts, the SIM-G remains a useful tool to provide estimates of head impact exposure for soccer players.

Citizen-led sampling to monitor phosphate levels in freshwater environments using a simple paper microfluidic device

Contamination of waterways is of increasing concern, with recent studies demonstrating elevated levels of antibiotics, antidepressants, household, agricultural and industrial chemicals in freshwater systems. Thus, there is a growing demand for methods to rapidly and conveniently monitor contaminants in waterways. Here we demonstrate how a combination of paper microfluidic devices and handheld mobile technology can be used by citizen scientists to carry out a sustained water monitoring campaign. We have developed a paper-based analytical device and a 3 minute sampling workflow that requires no more than a container, a test device and a smartphone app. The contaminant measured in these pilots are phosphates, detectable down to 3 mg L-1. Together these allow volunteers to successfully carry out cost-effective, high frequency, phosphate monitoring over an extended geographies and periods.