Conventional Direct Measurements Research Articles

Assessment of Soil Horizons and Their Matric Potential from Ground-Penetrating Radar Signal Attributes

Soil plays significant roles in different phases and in the continuous existence of human life. Its comprehensive knowledge, particularly as related to its physical characteristics, enhances its utilization, conservation, and management. The traditional methods of soil study are characterized with some pitfalls such as much time needed to perform such assessments. There are also issues of invasiveness that affect the soil structures and discrete sampling that may not reflect true spatial attributes in the outcome of such techniques. These problems are largely due to the concealing nature of soil layers that made its thorough evaluation difficult. In this study, an alternative geophysical approach has been adopted. The technique is the ground-penetrating method (GPR) that utilizes electromagnetic pulse energy via its equipment’s sensors, which can allow the investigation of soil properties, even in its concealing state. This study aimed at qualitatively evaluating the soil horizons and the matric potentials using the GPR signal attributes within the unsaturated zone with a view of having insight into the test field’s characterization. Field data measurements were obtained using MALA ProEX GPR equipment with its accessories manufactured by MALA Geosciences, Stockholm, Sweden. Evaluation of the processed field data results and computed attributes show soil characteristics variations with depth that was interpreted as the layers. This can be seen from the GPR data presentation as an image representing the subsurface of the zones of propagation of the pulse energy. Spectral analysis of the GPR signals allows for the delineation of two zones of contrasting features, which were tagged as high and low matric potentials. Although the conventional direct measurement of the matric potential was not made at the time of the study to complement and confirm the veracity of the approach, the results indicate the possibility of the approach towards a quick and in situ technique of soil investigations. Such evaluation may be valuable input in precision agriculture where accurate data are sought for implementation.

Remote estimation of cable tension using catenary theory and point clouds obtained by terrestrial laser scanning

This study addressed the structural health monitoring of civil engineering cable structures, in which single cable tension is the key parameter influencing safe and intended behaviour. Traditional methods for monitoring the tension force in a cable are labour-intensive and require direct interaction with the cable. In contrast, the proposed approach provides a remote and rapid assessment of the tension force in the cables of engineering structures using only the shape of the cable. First, a terrestrial laser scanner was used to acquire a point cloud of the cable geometry from a distance. Catenary theory was subsequently applied to the point cloud data to calculate the theoretical tensile force in the observed cable. When the results were compared with those obtained through conventional direct measurements using a dynamometer, the differences were negligible. The proposed approach was subsequently demonstrated on the actual in-service overhead contact lines of a tram system. The results indicated that the precision of the proposed approach is highly dependent on the accuracy of the data describing the physical properties of the cable (cable linear mass). Thus, the proposed approach was proven to be precise, reliable, and rapid, and directions for future research were discussed accordingly.

Simultaneous Reconstruction of Multiple Time-Varying Thermal Properties Based on Translucent Materials.

In the realm of high-tech materials and energy applications, accurately measuring the transient heat flow at media boundaries and the internal thermal conductivity of materials in harsh heat exchange environments poses a significant challenge when using conventional direct measurement methods. Consequently, the study of photothermal parameter reconstruction in translucent media, which relies on indirect measurement techniques, has crucial practical value. Current research on reconstructing photothermal properties within participating media typically focuses on single-objective or time-invariant properties. There is a pressing need to develop effective methods for the simultaneous reconstruction of time-varying thermal flow fields and internal thermal conductivity at the boundaries of participating media. This paper introduces a computational model based on the numerical simulation theory of internal heat transfer systems in participating media, stochastic particle swarm optimization algorithms, and Kalman filter technology. The model aims to enable the simultaneous reconstruction of various thermal parameters within the target medium. Our results demonstrate that under varying levels of measurement noise, the inversion results for different target parameters exhibit slight oscillations around the true values, leading to a reduction in reconstruction accuracy. However, overall, the model demonstrates robustness and accuracy in ideal conditions, validating its effectiveness.

Wall shear stress measurement of turbulent bubbly flows using laser Doppler displacement sensor

A novel wall shear stress meter is developed to promote studies of frictional drag reduction by injecting air bubbles into a turbulent boundary layer. Such studies require a tool having a time resolution sufficiently high to capture the unsteady effect of turbulent characteristics due to various bubble passage patterns. The present study adopts the principle of the heterodyne interferometer to capture of time variation of wall shear stress in turbulent flow up to 500 Hz in sampling frequency. We demonstrate the performance of the tool by applying it to bubbly flows beneath a flat-bottom model ship running at 3 m/s in a towing water reservoir, where bubbles experience wavy passage around a few Hz in frequency. The data obtained by the proposed shear stress meter agree well with Dean's formula for single-phase turbulent channel flow. The scattering of the data across three trials is sufficiently small, at approximately 3 %. This high reproducibility is a great advantage over conventional direct measurements, which have low reproducibility and a large scatter of the data of approximately 15 %. The obtained results represent reasonable drag reductions by injecting bubbles with different void fractions. We also evaluate histogram of the wall shear stress fluctuation to characterize the effect of drag reduction by unsteady passage of bubbles.

Explainable artificial intelligence for building energy performance certificate labelling classification

The building energy performance certificates (EPC) are widely adopted for sustainable development and improvement in building energy efficiency. Different from the conventional direct measurement based approach of acquiring a building’s EPC label, this study proposes a novel and alternative approach to classify a building’s EPC label using artificial neural network (ANN) models. Given the extensive best building EPC practices in developed countries, historical building EPC data and experiences can expedite the development and improvement of this procedure in developing countries. This study first develops the ANN classification model to attain the building EPC label. The classification result shows that the building EPC classification can achieve a 99% precision with sufficient input data. With the assistance of explainable artificial intelligence (XAI) tools such as the Local Interpretable Model-Agnostic Explanation (LIME) and SHapley Additive exPlanation (SHAP), some less important input features for the ANN classification models can be removed without severely influencing the ANN model’s accuracy. In the case studies, the EPC best practices historical registry data from Lombardy, Italy are used in training the ANN model. The ANN models’ accuracy for the case study 1 is 93% with 14 input features where CO2 emissions and net surface area are the two most influential features. The most influential input feature for case study 2 is the winter AC non-renewable energy performance, and the accuracy of the case study 2 ANN model is 89% with 26 input features.

Thrust measurement of an ion thruster by a force probe approach and comparison to a thrust balance

A key parameter when characterizing the performance of an electric propulsion system is obviously its thrust. The thrust can be either determined directly using a so-called thrust balance or deduced from indirect measurements. Here, we present a comparison of thrust measurements of the same radio frequency ion thruster in the thrust range from 250 μN to 1.5 mN using three different approaches: a conventional direct measurement employing a thrust balance and two indirect measurements, one based on a force probe located stationary in the thruster’s plume in conjunction with a scan of the ion beam profile using a Faraday-array scanner, and another one based on a measurement of the beam current at the grid system and a correction for beam divergence deduced from the Faraday-array scans. The results of the three approaches are compared for different beam currents, and pros and cons of the approaches are discussed.

Few‐shot learning based multi‐weather‐condition impedance identification for MPPT‐controlled PV converters

The broadband impedance of converters is an essential feature for the stability analysis of new energy sources. However, obtaining the impedance for photovoltaic (PV) converters with Maximum Power Point Tracking (MPPT) control is challenging because of their non-linear control schemes and real-time changing operating points. In this case, conventional linearized impedance modelling methods are not applicable, and conventional direct measurement approaches are highly time-consuming. This paper proposes a few-shot learning approach for quick access to PV converters’ impedance. The proposed method is based on the model agnostic meta-learning (MAML) algorithm, suitable for MPPT-controlled converters whose impedance changes with time, temperature, and irradiation. In the training process, it adjusts the initial model of the machine learning algorithm under different weather conditions. After completing the training, the initial model can adapt to a new condition with very few samples. Under this approach, with only a few data measured at several frequency points, broadband impedance for MPPT-controlled converters under any weather conditions can be accurately predicted, avoiding time-consuming measurements and inaccurate prediction of existing methods. Contrast simulation results show the effectiveness and superiority of the proposed method.

Enhanced Weak-Value Amplification via Photon Recycling.

In a quantum-noise limited system, weak-value amplification using postselection normally does not produce more sensitive measurements than standard methods for ideal detectors: the increased weak value is compensated by the reduced power due to the small postselection probability. Here, we experimentally demonstrate recycled weak-value measurements using a pulsed light source and optical switch to enable nearly deterministic weak-value amplification of a mirror tilt. Using photon counting detectors, we demonstrate a signal improvement by a factor of 4.4±0.2 and a signal-to-noise ratio improvement of 2.10±0.06, compared to a single-pass weak-value experiment, and also compared to a conventional direct measurement of the tilt. The signal-to-noise ratio improvement could reach around six for the parameters of this experiment, assuming lower loss elements.

Indirect Method for Measuring Absolute Acoustic Nonlinearity Parameter Using Surface Acoustic Waves with a Fully Non-Contact Laser-Ultrasonic Technique

This paper proposes an indirect method to measure absolute acoustic nonlinearity parameters using surface acoustic waves by employing a fully non-contact laser-ultrasonic technique. For this purpose, the relationship between the ratio of relative acoustic nonlinearity parameters measured using the proposed method in two different materials (a test material and a reference material) and the ratio of absolute acoustic nonlinearity parameters in these two materials was theoretically derived. Using this relationship, when the absolute nonlinearity parameter of the reference material is known, the absolute nonlinearity parameter of the test material can be obtained using the ratio of the measured relative parameters of the two materials. For experimental verification, aluminum and copper specimens were used as reference and test materials, respectively. The relative acoustic nonlinearity parameters of the two materials were measured from surface waves generated and received using lasers. Additionally, the absolute parameters of aluminum and copper were measured using a conventional direct measurement method, with the former being used as a reference value and the latter being used for comparison with the estimation result. The absolute parameter of copper estimated by the proposed method showed good agreement with the directly measured result.

Polarization-Modulated, Goos⁻Hanchen Shift Sensing for Common Mode Drift Suppression.

A polarization-modulation-based Goos–Hanchen (GH) sensing scheme leveraging the polarization-dependence of the Bloch surface wave enhanced GH shift is proposed and experimentally demonstrated. Based on a simple setup utilizing a liquid crystal modulator to switch the polarization state of the input beam periodically, the alternating positions of the reflected beam for both polarizations are monitored by a lock-in amplifier to handily retrieve the GH shift signal. The conventional direct measurement of the beam position for the target state of polarization is vulnerable to instabilities in the optomechanical setup and alignment. Our proposed scheme provides a sensitive yet robust GH shift-sensing setup where the common mode drift and noise could be suppressed to ensure better system stability.

Offline Health Diagnosis of Power Device Based on Nonintrusive Inductively Coupled Approach

Understanding the causes of a power device’s defect plays a crucial role in failure and reliability analyses, and hence, the need of health diagnosis. Health diagnosis involves the measurement of predefined electrical parameters of a power device under its usual operating condition and the analyses of their deviations from their norms. Instead of the conventional direct measurements of voltage and current waveforms in time domain, this paper proposes a nonintrusive measurement method that measures the ON-state impedance of a power device in frequency domain. The proposed method eliminates direct electrical contact with the device-under-test, and it has the ability to detect the deviation of the ON-state impedance from its norm for health diagnosis purpose.

Comparison of a semiautomatic protocol using plastering and three‐dimensional scanning techniques with the direct measurement protocol for hand anthropometry

AbstractThis study aimed to compare a three‐dimensional (3D) semiautomatic measurement protocol (3D‐SAMP) that measures hand dimensions using a plaster hand and a 3D scanner with the conventional direct measurement protocol (DMP). An experiment was conducted to measure 52 dimensions of one hand by 20 measurers with three repetitions. The locations of landmarks attached to the plaster hand were automatically identified and then measurements of the hand dimensions were automatically extracted in the 3D‐SAMP. Significant measurement differences with a range of 2.1 to 4.4 mm between the 3D‐SAMP and the DMP were observed in 13 out of the 52 dimensions, and the 3D‐SAMP showed better reliability than the DMP in terms of intra‐ and intermeasurer variability. The 3D‐SAMP was found significantly faster and easier in hand measurement than the DMP (11.1 ± 3.5 min for 3D‐SAMP and 17.8 ± 4.5 min for DMP; 5.2 ± 0.8 for 3D‐SAMP and 4.3 ± 0.8 for DMP using a 7‐point scale with 1 for very dissatisfied and 7 for very satisfied for ease of measurement) when fabrication (about 1 hr 10 min) and scanning (3 min) of a plaster hand were not considered. The proposed 3D‐SAMP is applicable only to plaster hands available in hand measurement.

Performance evaluation of optical beamforming-based wideband antenna array (Invited Paper)

A wideband-generalized pattern multiplication approach to evaluate the performance of an optical beamforming-based wideband antenna array is proposed and experimentally demonstrated, which enables the far-field measurement of a large wideband array with a small anechoic chamber. Because the optimum reception of a wideband microwave signal is highly related to the time-domain distortions of the beamforming system, a correlation-receiver-based radiation pattern is applied to take the fidelity of the wideband signals into account. A four-element optical beamforming system is built to verify the feasibility of the proposed method. The results achieved by the proposed method agree well with the conventional direct measurements.

Use of a reciprocity technique to measure the radiation efficiency of a vibrating structure

The reciprocity principle is well-known and has many applications in acoustics and vibro-acoustics. This paper discusses a reciprocity measurement method to determine the radiation efficiency of a vibrating structure. The method comprises two steps: (i) measurements of the acceleration response of the structure induced by a sound field in a reverberation chamber and (ii) measurements of the spatially-averaged squared transfer mobility of the structure. The approach is more flexible than a direct method and has the advantage that no shaker is required to excite the structure in the acoustic measurements. To demonstrate the applicability of this method, experiments were conducted on rectangular flat plates, on two components of a railway track test-rig and on three different built-up structures. For the plates and the railway rig components, comparisons are also made with theoretical models. It is shown that the measured results for each arrangement obtained using this reciprocity method provide good agreement with conventional direct measurements and with theoretical modelling. However, in most of the examples presented, the direct method has been found to be less practical and sometimes even less accurate than the reciprocal one, mostly due to the structure-shaker connection and to the inherent uncertainty of acoustic intensity measurements.

Compressive direct measurement of the quantum wave function.

The direct measurement of a complex wave function has been recently realized by using weak values. In this Letter, we introduce a method that exploits sparsity for the compressive measurement of the transverse spatial wave function of photons. The procedure involves weak measurements of random projection operators in the spatial domain followed by postselection in the momentum basis. Using this method, we experimentally measure a 192-dimensional state with a fidelity of 90% using only 25 percent of the total required measurements. Furthermore, we demonstrate the measurement of a 19,200-dimensional state, a task that would require an unfeasibly large acquiring time with the standard direct measurement technique.

From Yang-Mills Photon in Curved Spacetime to Dark Energy Density

We start from quantum field theory in curved spacetime to derive a new Einstein-like energy mass relation of the type E=γmc2 where γ=1/22 is a Yang-Mills Lorentzian factor, m is the mass and c is the velocity of light. Although quantum field in curved spacetime is not a complete quantum gravity theory, our prediction here of 95.4545% dark energy missing in the cosmos is almost in complete agreement with the WMAP and supernova measurements. Finally, it is concluded that the WMAP and type 1a supernova 4.5% measured energy is the ordinary energy density of the quantum particle while the 95.5% missing dark energy is the energy density of the quantum wave. Recalling that measurement leads to quantum wave collapse, it follows that dark energy as given by E(D) = mc2 (21/22) cannot be detected using conventional direct measurement although its antigravity effect is manifested through the increasing rather than decreasing speed of cosmic expansion.

손 치수 측정을 위한 3차원 반자동 측정 방법 개발

Measurement protocols for hand anthropometry have been studied for ergonomic product design. The present study developed a 3D semi-automatic measurement protocol (3D-SAMP) which semi-automatically measures various hand dimensions using a 3D scanner. The 3D-SAMP was compared with the conventional direct measurement method (DMM) to examine its effectiveness. The 3D-SAMP consists of (1) fabricating a plaster cast of the hand, (2) placing landmarks on the plaster hand, (3) scanning the plaster hand with a 3D scanner, (4) identifying automatically the positions of the landmarks on the digital hand, and (5) extracting automatically hand anthropometric measurements (lengths, widths, thicknesses, and circumferences). An evaluation experiment conducted in the study found the 3D-SAMP preferred to the DMM in terms of reliability (the number of dimensions exceeding the variability criteria SD=2 mm and CV=5% : 3D-SAMP =2 and DMM=24) and ease of measurement (3D-SAMP=5.2 and DMM=4.3 out of 7). The 3D-SAMP can be applied to ergonomic design of a hand-held product.

Development of a 3D Semi-Automatic Measurement Protocol for Hand Anthropometric Measurement

Measurement protocols for hand anthropometry have been studied for ergonomic product design. The present study developed a 3D semi-automatic measurement protocol (3D-SAMP) which semi-automatically measures various hand dimensions using a 3D scanner. The 3D-SAMP was compared with the conventional direct measurement protocol (DMP) to examine its effectiveness. The 3D-SAMP consists of (1) fabricating a plaster cast of the hand, (2) placing landmarks on the plaster hand, (3) scanning the plaster hand with a 3D scanner, (4) automatically identifying the positions of the landmarks on the digital hand, and (5) automatically extracting hand anthropometric measurements (lengths, widths, thicknesses, and circumferences). An evaluation experiment was conducted and found the 3D-SAMP preferred to the DMP in terms of reliability, efficiency, and ease of measurement.