Load Measurement System Research Articles

Experimental, numerical and analytical investigations into the internal inversion of mild steel tubes under high velocity axial impact using a die

This paper investigates the internal inversion process of mild steel tubes under axial impact analytically, numerically and experimentally using a die. The analytical model which is based on the energy method, is able to predict the shortening length of the tube and the required force for tube inversion considering tube thickness variation. In order to validate the analytical model, some experimental tests are performed on the steel tubes in a gas gun and the required force for tube inversion is obtained using an impact loading measurement system. The tube inversion process is also simulated using the finite element software Abaqus and finally the obtained results are compared with each other. In the present paper, the effect of impact parameters included the projectile mass and velocity, is investigated on deformation mechanism and energy absorption of the tubes in the internal inversion process. The effect of tube thickness and die radius are also studied in the mentioned process. It is observed that in the situation of constant projectile mass, increasing the impact velocity doesn’t have a tangible effect on the inversion force and just increases the tube displacement, but if the impact velocity remains constant, increasing the projectile mass causes increase in the inversion force as well as increased tube displacement. It is also concluded that increasing the tube wall thickness increases the inversion force which makes the tube not to be a good absorbent and decreases the tube displacement. Comparing the experimental, analytical and numerical results provides good agreements between them.

Development of a Plow Tillage Cycle for an Agricultural Tractor

<abstract> <b><sc>Abstract.</sc></b> Various field tests are needed to improve agricultural tractor performance; however, field tests require expenditures for constructing an experiment system and time for conducting the tests repeatedly. In addition, it is difficult to acquire reliable data because field tests depend on environmental conditions. For this reason, indoor tests using dynamometers have been used in the automotive industry instead of field tests. To ensure the reliability of indoor tests, standardized driving cycles are needed as input data for the dynamometer. Therefore, this study aimed to develop a standardized plow tillage cycle for agricultural tractors using real field data. A load measurement system was installed on a tractor to collect real field data from loads acting on the four driving axles and the hydraulic pumps. Plow tillage was conducted on ten farmlands of similar size (3000 m²; 100 m x 30 m) at three sites (A, B, and C). The plow tillage cycles for each site were developed using the driving cycle construction method for conventional vehicles with the measured load data. At one site, the entire dataset from the ten farmlands was first classified into micro-trips, which were the minimum patterns of plow tillage including plowing, three-point hitch ascending, and tractor turning. The arbitrary working cycles were generated by combining micro-trips, and less than 5% absolute percentage error was achieved between the entire dataset and the generated arbitrary working cycle. Second, the plow tillage cycle was determined considering the sum square difference (SSD) with a torque and torque variation probability distribution. The selected working cycle with the lowest SSD was determined as the plow tillage cycle. Third, the performance values (PVs) of the plow tillage cycles of agricultural tractors and the driving cycles of conventional vehicles were compared to evaluate the performance of the plow tillage cycle. The results showed that the ranges of absolute percentage error relative to the entire dataset were 1.0% to 4.9% for all sites. The SSDs of the plow tillage cycles were 1195.96, 958.77, and 1202.50, and the PVs of the plow tillage cycles were 99.60, 77.90, and 84.15 for sites A, B, and C, respectively. The PVs of the commonly used driving cycles were low, at 60% to 125% of the plow tillage cycles. The plow tillage cycles had especially higher performance than some of the international standard driving cycles by 104% to 125% for site B. The results showed that the developed plow tillage cycles can be applied to indoor tests for performance evaluation of agricultural tractors.

Load Location and Measurement System Based on Fiber Bragg Grating Sensor

Load Location and Measurement System Based on Fiber Bragg Grating Sensor

ロードセル対向式衝撃荷重測定装置の開発

ロードセル対向式衝撃荷重測定装置の開発

Voice source under cognitive load: Effects and classification

Cognitive load refers to the mental demand experienced while performing a cognitive task. A cognitive load measurement system can potentially be a useful tool for monitoring and enhancing human task performance. In the area of speech-based cognitive load classification, while there are various spectral and vocal tract-based features proposed for classification purposes, there is still a lack of studies that investigate how cognitive load affects the voice source, and whether glottal features are effective in cognitive load classification systems. This work introduces a set of databases that contains both speech and electroglottograph (EGG) data. Using these databases, we present results that provide arguably the first direct insight into how cognitive load affects the voice source. Additionally, we show that glottal-based features carry complementary information with respect to formant-based features, and that fusion between glottal and formant-based systems produces classification results that are comparable with (if not better than) existing baseline systems across three out of five evaluation databases.

Pre-processing of load data of agricultural tractors during major field operations

Development of highly efficient and energy-saving tractors has been one of the issues in agricultural machinery. For design of such tractors, measurement and analysis of load on major power transmission parts of the tractors are the most important pre-requisite tasks. Objective of this study was to perform pre-processing procedures before effective analysis of load data of agricultural tractors (30, 75, and 82 kW) during major field operations such as plow tillage, rotary tillage, baling, bale wrapping, and to select the suitable pre-processing method for the analysis. A load measurement systems, equipped in the tractors, were consisted of strain-gauge, encoder, hydraulic pressure, and radar speed sensors to measure torque and rotational speed levels of transmission input shaft, PTO shaft, and driving axle shafts, pressure of the hydraulic inlet line, and travel speed, respectively. The entire sensor data were collected at a 200-Hz rate. Plow tillage, rotary tillage, baling, wrapping, and loader operations were selected as major field operations of agricultural tractors. Same or different farm works and driving levels were set differently for each of the load measuring experiment. Before load data analysis, pre-processing procedures such as outlier removal, low-pass filtering, and data division were performed. Data beyond the scope of the measuring range of the sensors and the operating range of the power transmission parts were removed. Considering engine and PTO rotational speeds, frequency components greater than 90, 60, and 60 Hz cut off frequencies were low-pass filtered for plow tillage, rotary tillage, and baler operations, respectively. Measured load data were divided into five parts: driving, working, implement up, implement down, and turning. Results of the study would provide useful information for load characteristics of tractors on major field operations.

Landing Gear Ground Load Measurement and Verification Test for a Large Passenger Jet

Engineered Material Arresting System (EMAS) could be constructed in runway end safety area to arrest an overrun aircraft. EMAS bed is the main part of EMAS and consists of the EMAS material, such as foam concrete. EMAS and its design method should be verified by actual aircraft test. A large passenger jet, one main aircraft type of civil aviation should be used in actual aircraft verification test of EMAS. The jet came from an airline operation front line. To minimize the effect of the test on the jet's airworthiness, the landing gears of the jet should not be remove in the measurement system mounting. The jet's motion in EMAS could be analyzed, and the performance requirement of landing gear load measurement system could be studied. Accordingly, landing gear load measurement system and field calibration test method were presented. For the verification of measurement system, the aircraft taxi tests such as taxi brake test, engine ground run up test and a short EMAS bed test had been done with the system. Through analyzing the measured loads of the landing gears, weight of the jet and the limit load of landing gears, the system could be verified. The results show that the load measurement system could satisfy EMAS actual aircraft verification test, and the test and verification method should satisfy other large aircraft landing gear load measurement

立位時における人体前額面の姿勢制御モデルの検討（周波数応答実験による伝達関数モデルの同定）

We have been developing a standing ride type vehicle, such as electric skateboards. A human dynamics model is required to assist balance control of human standing in the vehicle. So far, however, little information has emerged on the human balance control mechanism. The purpose of this study is to construct a transfer function model of human body dynamics on frontal plane when the support surface moves to horizontal direction. The present investigation deals with the dynamics in low frequency range (below 4rad/s) with parallel stance. We assumed a human mechanical model as one degree-of-freedom system. In a previous paper we estimated characteristic roots of the human standing model from impulse response tests. Here we report a procedure to identify a transfer function model describing the system definitely from the result of impulse response tests and frequency response tests. Reference acceleration for the support surface in the frequency response test was composed of six trigonometric functions from 1.0 rad/s to 4.0 rad/s. Posture angle of the body and moment generated from support surface were measured by a motion capture system and a load measurement system respectively. The human model was identified by two steps in the present method. We estimated the characteristic roots from the result of impulse response test in first step. Then it allowed us to define denominator of the transfer function model as the estimated characteristic polynomial. In second step, we identified numerator of the transfer function model from the result of frequency response test by least square method. The present method enabled us to identify a low-dimensional transfer function model accurately from experimental data with large variability.

Thermal Borehole Shear Device

This paper presents the details of a new modified borehole shear device that has the capability of measuring the impact of temperature on the in situ shear stress–displacement curves for soil–concrete interfaces. The thermal borehole shear device incorporates concrete shoes with embedded heaters, a pneumatic loading device for application of horizontal normal stresses, and an automated loading system with local vertical displacement and load measurement systems that permits either displacement–control or load–control testing. A methodology for measurement of the soil–concrete shear stress–displacement curves and for evaluation of the drained interface shear strength failure envelopes at different temperatures is presented in this study. Typical results from proof-of-concept tests performed in a clay layer compacted in a laboratory tank in a borehole in a silty sand deposit in the field are presented in this paper. The results are synthesized to show how the impacts of temperature and normal stress on the normalized shear stress–displacement curves can be evaluated. These normalized curves can be measured on a site-specific basis for the calibration of thermo-mechanical load transfer analyses or finite element analyses, which are often used to design and evaluate soil–structure interaction in drilled shaft foundations with geothermal heat exchangers (energy foundations).

Development of a Cryogenic Calorimeter for Investigating Beam-Based Heat Load of Superconducting Undulators

Superconducting undulators provide higher magmatic field to increase the brilliance and photon energy of synchrotron light sources. To quantify the amount of beam-based heat load of storage rings and optimize the design of cryogenic system, Lawrence Berkeley National Laboratory (LBNL) proposed a cryogenic calorimeter to perform the working condition of superconducting undulators. The calorimeter has been developed by Shanghai Institute of Applied Physics (SINAP) and installed on storage ring of Shanghai Synchrotron Radiation Facility (SSRF). Also, online experiments started in September of 2012. This paper describes the cryogenic system and beam-based heat load measurement system. Also, some measurement results are given in the paper.

Determination of Tensile Properties of Hemp-Fiber Bundle by Using Tensile Testing Equipment with Raspberry Pi

Tensile strength of some natural fibers such as hemp is higher than that of steel. To determine tensile properties of hemp fiber, a fiber or bundle is tensile tested with universal testing machine that is controlled by personal computer. This paper presents a small tensile testing equipment that is controlled by Raspberry Pi (RPi), a credit-card-sized single-board computer. General Purpose Input Output (GPIO) pins on RPi were used for controlling the machine crosshead and receiving the tensile load that apply to a hemp bundle. A stepper motor was used to drive the crosshead. Tensile load was measured by using a load measurement system included load-cell, instrument amplifier, and analog-to-digital converter. The applied load and extension were real-time displayed and continuously recorded throughout the test. Testing hemp-fiber bundles with the proposed equipment found that their tensile strength and Youngs modulus were 446.75±184.36 MPa and 18.23±8.26 GPa, respectively. These results were in good agreement with the properties founded in other publications. Test results also found that hemp-fiber bundle with smaller diameter showed higher tensile strength than that of larger one.

3A1-N03 自転車走行時の自転車各部にかかる荷重計測システムの開発(感覚・運動・計測(1))

3A1-N03 自転車走行時の自転車各部にかかる荷重計測システムの開発(感覚・運動・計測(1))

Development of Multichannel Data Acquisition System Based on Wheel Load Measuring Plate

The wheel load measuring plate is a force sensor based on strain measurement, it can bear simultaneously multidimensional force load and identify radial wheel load by decoupling. The measuring plate can output multichannel voltage signal, usually each channel has the properties of weak signal, strong noise, poor anti-jamming ability. The paper discusses the development of a multichannel data acquisition system for the wheel load measuring plate and conducts the experimental verification, through the data acquisition system achieve time-sharing acquisition of multichannel data, improving the precision and anti-jamming ability of wheel load measurement system.

Effects of gear selection of an agricultural tractor on transmission and PTO load during rotary tillage

For better performance and durability of a tractor during field operations, it is necessary to select the optimal gear setting for the operation. The purpose of this study was to analyze effects of the gear selection on load acting on the transmission and PTO shafts of a 75kW agricultural tractor during rotary tillage with a 20-cm tillage depth. In order to measure the loads acting on the transmission and PTO input shafts, a load measurement system was installed on the tractor. The system consisted of strain-gauge sensors to measure the torque on the transmission and PTO input shafts, a radio telemetry I/O interface to acquire the sensor signals, and embedded software to acquire the data. Rotary tillage was conducted at three ground speeds and three PTO rotational speeds under upland field sites with the same soil conditions. The load data was converted to a load spectrum using the rain-flow counting and SWT (Smith Watson Topper) equations. Sum of damage due to the load was calculated using the Modified Miner's rule for each gear selection, and then the load severeness was calculated as the relative magnitude of the damage sum. The average torque on the transmission input shaft increased significantly as the ground speed increased from L1 (1.87kmh−1) to L3 (3.77kmh−1) at the same PTO rotational speed. Also, the average torque on the PTO input shaft increased as the PTO rotational speed increased at the same ground speed. Rotary tillage exerted significantly greater loads on the PTO input shaft than on the transmission input shaft. The severeness of the load on the transmission and PTO shafts increased, indicating possible decreased fatigue life, as both the ground and PTO rotational speeds increased. Results of the study might provide information useful for optimum gear selection for rotary tillage, considering not only field efficiency, but load severeness on the transmission and PTO input shafts.

Automatic classification of eye activity for cognitive load measurement with emotion interference

Measuring cognitive load changes can contribute to better treatment of patients, can help design effective strategies to reduce medical errors among clinicians and can facilitate user evaluation of health care information systems. This paper proposes an eye-based automatic cognitive load measurement (CLM) system toward realizing these prospects. Three types of eye activity are investigated: pupillary response, blink and eye movement (fixation and saccade). Eye activity features are investigated in the presence of emotion interference, which is a source of undesirable variability, to determine the susceptibility of CLM systems to other factors. Results from an experiment combining arithmetic-based tasks and affective image stimuli demonstrate that arousal effects are dominated by cognitive load during task execution. To minimize the arousal effect on CLM, the choice of segments for eye-based features is examined. We then propose a feature set and classify three levels of cognitive load. The performance of cognitive load level prediction was found to be close to that of a reaction time measure, showing the feasibility of eye activity features for near-real time CLM.

An investigation into the mechanical characteristics of select self-ligated brackets at a series of clinically relevant maximum torquing angles: loading and unloading curves and bracket deformation

Edgewise orthodontic treatment utilizes a force couple in order to achieve labial-lingual tooth angulation. Two self-ligating brackets (Damon Q and Speed) were examined across a range of clinically relevant torques in order to assess the loading and unloading curves and bracket deformation. A previously developed torquing and load measurement system was utilized to rotate a 0.199 × 0.25 in stainless steel wire in a fixed bracket slot to the following angles: 16, 20, 24, 28, 32, and 40 degrees. The torque on the bracket was measured during both wire loading and unloading cycles. The torque play for the Damon brackets was determined to increase by less than 0.4 degrees when torqued to 70 Nmm, whereas the increase for the Speed brackets was 2.1 degrees at the same torque magnitude. The deformation curves for the Damon and Speed brackets were found to be different for loading and unloading. Speed brackets were found to start to plastically deform when torqued to 24 degrees (26 Nmm of torque), while Damon brackets did not plastically deform until 28 degrees (38 Nmm of torque). Damon brackets were found not to plastically deform as easily and to have a smaller increase in torque play than Speed brackets. Both the Damon and the Speed brackets demonstrated minimal effect of plastic deformation and torque play at maximum angles of twist less than 20 degrees. Torque measured in the brackets was different for loading and unloading.

Spatio-Temporal Mining for Power Load Forecasting in GIS-AMR Load Analysis Model

A spatio-temporal mining technique is used to predict power load patterns for a voltage transformer. It is applied from load data measured every thirty minutes and a GIS-AMR database collected by a transformer's load measurement system over a wireless network. The proposed approach in this paper consists of three stages, (i) data preprocessing: noise or outlier is removed and the continuous attribute-valued features are transformed to new features (feature extraction and discretization), (ii) cluster analysis: SOMs (Self Organizing Maps) clustering is used to label the class and (iii) classification: we used and evaluated classification rules using spatio-temporal mining to build a suitable load forecasting model. In order to evaluate the result of classification, derived class labels from clustering and other features are used as input to build classification rules including time and spatial factors. Lastly, the result of our experiments is presented.

Formant Frequencies under Cognitive Load: Effects and Classification

Cognitive load measurement systems measure the mental demand experienced by human while performing a cognitive task, which is useful in monitoring and enhancing task performance. Various speech-based systems have been proposed for cognitive load classification, but the effect of cognitive load on the speech production system is still not well understood. In this work, we study formant frequencies under different load conditions and utilize formant frequency-based features for automatic cognitive load classification. We find that the slope, dispersion, and duration of vowel formant trajectories exhibit changes under different load conditions; slope and duration are found to be useful features in vowel-based classification. Additionally, 2-class and 3-class utterance-based classification results, evaluated on two different databases, show that the performance of frame-based formant features was comparable, if not better than, baseline MFCC features.

Flapping Wing Structural Deformation and Thrust Correlation Study with Flexible Membrane Wings

This experimental study investigates the relationship between flapping wing structure and the production of aerodynamic forces for micro air vehicle hovering flight by measuring full-field structural deformation and thrust generation. Results from four flexible micromembrane wings with different skeletal reinforcement demonstrate that wing compliance is crucial in thrust production: only certain modes of passive aeroelastic deformation allow the wing to effectively produce thrust. The experimental setup consists of a flapping mechanism with a single-degree-of- freedom rotary actuation up to 45 Hz at 70 deg stoke amplitude and with power measurement, a force and torque sensor that measures the lift and thrust, and a digital image correlation system that consists of four cameras capable of capturing the complete stroke kinematics and structural deformation. Several technical challenges related to the experimental testing of microflapping wings are resolved in this study: primarily, flapping wings less than 3 in. in length produce loads and deformations that are difficult to measure in an accurate and nonintrusive manner. Furthermore, the synchronization of the load measurement system, the vision-based wing deformation measurement system, and the flapping mechanism is demonstrated. Intensive data analyses are performed to extract useful information from the measurements in both air and vacuum.

Evaluation of the Material Properties of an OFHC Copper Film at High Strain Rates Using a Micro-Testing Machine

The material properties of an oxygen-free high thermal conductivity (OFHC) film with a thickness of 0.1 mm were evaluated at strain rates ranging from 10−3/s to 103/s using a high-speed material micro-testing machine (HSMMTM). The high strain-rate material properties of thin films are important especially for an evaluation of the structural reliability of micro-formed parts and MEMS products. The high strain-rate material testing methods of thin films, however, have yet to be established to the point that the testing methods of larger specimens for electronics, auto-body, train, ship, and ocean structures are. For evaluation, a new type of HSMMTM was developed to conduct high-speed tensile tests of thin films. This machine is capable of testing at a sufficiently high tensile speed with an electromagnetic actuator, a novel gripping mechanism, and an accurate load measurement system. The OFHC copper film shows high strain-rate sensitivity in terms of the flow stress, fracture elongation, and strain hardening. These measures increase as the tensile strain rate increases. The rate-dependent material properties of an OFHC copper film are also compared with those of a bulk OFHC copper sheet with a thickness of 1 mm. The flow stress of an OFHC copper film is relatively low compared to that of a bulk OFHC copper sheet in the entire range of strain rates, while the fracture elongation of an OFHC copper film is much larger than that of a bulk OFHC copper sheet. A quantitative comparison would provide material data at high strain rates for the design and analysis of micro-appliances and different types of micro-equipment.