Field Measurement Method Research Articles

Wheat growth monitoring and yield estimation based on remote sensing data assimilation into the SAFY crop growth model

Crop growth monitoring and yield estimate information can be obtained via appropriate metrics such as the leaf area index (LAI) and biomass. Such information is crucial for guiding agricultural production, ensuring food security, and maintaining sustainable agricultural development. Traditional methods of field measurement and monitoring typically have low efficiency and can only give limited untimely information. Alternatively, methods based on remote sensing technologies are fast, objective, and nondestructive. Indeed, remote sensing data assimilation and crop growth modeling represent an important trend in crop growth monitoring and yield estimation. In this study, we assimilate the leaf area index retrieved from Sentinel-2 remote sensing data for crop growth model of the simple algorithm for yield estimation (SAFY) in wheat. The SP-UCI optimization algorithm is used for fine-tuning for several SAFY parameters, namely the emergence date (D0), the effective light energy utilization rate (ELUE), and the senescence temperature threshold (STT) which is indicative of biological aging. These three sensitive parameters are set in order to attain the global minimum of an error function between the SAFY model predicted values and the LAI inversion values. This assimilation of remote sensing data into the crop growth model facilitates the LAI, biomass, and yield estimation. The estimation results were validated using data collected from 48 experimental plots during 2014 and 2015. For the 2014 data, the results showed coefficients of determination (R2) of the LAI, biomass and yield of 0.73, 0.83 and 0.49, respectively, with corresponding root-mean-squared error (RMSE) values of 0.72, 1.13 t/ha and 1.14 t/ha, respectively. For the 2015 data, the estimated R2 values of the LAI, biomass, and yield were 0.700, 0.85, and 0.61, respectively, with respective RMSE values of 0.83, 1.22 t/ha, and 1.39 t/ha, respectively. The estimated values were found to be in good agreement with the measured ones. This shows high applicability of the proposed data assimilation scheme in crop monitoring and yield estimation. As well, this scheme provides a reference for the assimilation of remote sensing data into crop growth models for regional crop monitoring and yield estimation.

Detection of Escherichia Coli Bacteria by Using Image Processing Techniques

Recently, image processing has proven itself as a fast and reliable technique in research in medicine and biology. Bacterial colony separation is an important and time-consuming process in studies in the field of microbiology. Bacteria counting is usually carried out by the naked eye or even by Coulter counter machines, which are based on the rather expensive electric field measurement method. In this study, image-based enumeration of Escherichia Coli over the colony morphology in the petri dish was investigated. In the experimental study, 4 different bacteria from the Enterobacteriaceae family were planted on petri dishes containing Eosin-methylene blue agar (Merck, Darmstadt, Germany). Escherichia Coli colony characteristics were determined by digitizing planted bacterial petri images. For the study, counting was done with the interface developed in MATLAB R2013a. After the classification criteria were determined, the method was tested on new petri dishes and successful results were obtained.

Measuring Electromagnetic Field Activity Generated by Neurons In Vivo by Humans With Thoughts of Repetitive Motor Activities and Emotional Thoughts.

BackgroundIn this study, a novel method of electromagnetic field (EMF) measurements of the human brain has been performed to evaluate neuronal activity. This measurement in a non-contact, non-invasive, continuous manner through the human skull and scalp in the standard environment is completed through a lightweight inexpensive helmet. We sought to further delineate whether specific activities of complex thought can be identified using this non-invasive technique.MethodologyNon-clinical human subject volunteers donned a lightweight helmet with attached sensors and performed activities of motor movement, specific motor imagery, and specific emotional imagery synchronized to an audible tone for consistency. The human subjects’ brain EMF was recorded and analyzed.ResultsThe novel method of continuously recording real-time human brain EMF was able to determine differing brain activity between individuals performing motor movement, motor imagery, and emotional imagery in a non-contact manner at different distances from the scalp.ConclusionsIt may be possible to measure specific human brain activity using EMF in a non-invasive fashion. Emotional imagery, motor imagery, and motor movement generate different EMFs that have different discernible forms compared to baseline activity.

Analysis on asymmetrical RCF cracks characterisation using an ACFM sensor and the influence of the rail head profile

Rolling contact fatigue (RCF) cracks are one of the typical surface-breaking defects that impairs the rail service life. RCF cracks propagation can deviate from regular semi-ellipse shapes, turning into asymmetrical profiles. RCF crack measurements using the alternating current field measurement (ACFM) method are unable to accurately characterise asymmetrical cracks, as the sizing algorithm is developed based on regular crack shapes. In this paper, the development of modelling capability to consider asymmetrical RCF cracks and the influence of asymmetrical shapes on ACFM signals are presented. A novel grid scan method using ACFM probe sensor for characterizing asymmetrical crack shapes is proposed. The influences of rail head profile on crack sizing are studied and result shows that it gives maximum 2 mm underestimation in crack depth if the worn rail head profile is not considered in ACFM sizing algorithm.

Research on Roof Cutting Pressure Relief of the Gob-Side Entry Retaining With Roadside Backfilling

Based on the application of the retained gob-side entry in a fully mechanized face E2307 headgate, the stress distribution and deformation characteristics of the roadside backfill body for different types of roof cutting were investigated in this study by employing a combination method of theoretical analysis, numerical simulation, and field measurement. The study uses RocLab software to accurately modify the lithology of the simulation area, discuss the position of roof cutting and the pressure relief parameters of roof cutting, and select the optimal solution of the roof-cutting plan. The results show that the advanced pre-cracking effectively blocks the stress transmission in the high-level roof strata; the roadway is in the stress unloading zone, the stress environment of the surrounding rock in the roadway is significantly optimized, and the deformation of the surrounding rock in the roadway is significantly reduced. In the roof-cutting scheme, the deformation of the surrounding rock in the 90° main roof-cutting scheme is reduced by 78% compared with the uncut roof and by 39% compared with the 90° immediate roof cutting. The research results were successfully applied at the E2307 headgate of the Gaohe coal mine; the maximum roof subsidence and the maximum rib convergence were 121 and 74 mm, respectively. Field monitoring indicates that the deformation of the retained entry was controllable, and the final retaining effects were good.

A novel positioning method for Hall magnetic field measurement of heavy ion accelerator

In the magnetic field measurement of accelerator magnets, the precise positioning of the magnetic field measurement system and the magnet is a basic and very important part. By analyzing the mechanical structure and working principle of Hall magnetic field measurement system, a novel positioning method is proposed in this research for the high-precision and fast positioning of magnet and Hall magnetic field measurement system. By measuring the geometric elements of the magnetic field measurement system and the calibration benchmark of the magnet, the geometric relationship between the magnetic field measurement system and the magnet is established, so as to quickly locate the magnet to the position and attitude required by the magnetic field measurement. The mechanical structure of the Hall probe of the magnetic field measurement system is optimized. Two special ceramic reflectors are installed on the vertical and horizontal axes corresponding to the center of the Hall sensor, and the two ceramic reflectors installed on the Hall probe is monitored with a laser tracker. In this way the Hall sensor can be intuitively positioned at the geometric center of the magnet with an accuracy better than 0.05 mm. In the measurement process, the magnetic field measurement trajectory of Hall sensor in the magnet can also be detected by monitoring the coordinates of ceramic reflector in real time. The practical application in Space Environment Simulation and Research Infrastructure (SESRI) magnet magnetic field measurement show that, compared with the traditional positioning method, the proposed positioning method not only improves the repeatability of Hall magnetic field measurement integral field by nearly 10 times, but also improves the positioning efficiency of magnetic field measurement. These results have verified the practicability and effectiveness of the proposed positioning method.

Two-Dimensional Flow Field Measurement Method for Sediment-Laden Flow Based on Optical Flow Algorithm

This paper proposes a novel particle image velocimetry (PIV) technique to generate an instantaneous two-dimensional velocity field for sediment-laden fluid based on the optical flow algorithm of ultrasound imaging. In this paper, an ultrasonic PIV (UIV) system is constructed by integrating a medical ultrasound instrument and an ultrasonic particle image velocimetry algorithm. The medical ultrasound instrument with a phased sensor array is used to acquire acoustic echo signals of particles in water and generate two-dimensional underwater ultrasound images. Based on the optical flow field, the instantaneous velocity of the particles in water corresponding to the pixels in the ultrasonic particle images is derived from the grayscale change between adjacent images under the L-K local constraint based on the optical flow field, and finally, the two-dimensional flow field is obtained. Through multiple sets of experiments, the proposed algorithm is verified. The experimental results are compared with those of the conventional cross-correlation algorithms. The results show that the L-K optical flow method can not only obtain the underwater velocity field accurately, but also has the advantages of good smoothness and extensive suitability, especially for the flow field measurement in sediment-laden fluid than conventional algorithms.

A practical method for field measurement of mean room surface exitance

Cuttle has proposed to use mean room surface exitance (MRSE) as a measure of spatial brightness for interior lighting design. One problem hindering the adoption of MRSE is the lack of a practical field-measurement method with verified accuracy. Although Cuttle suggested that MRSE can be estimated by measuring the illuminance caused by indirect light from a position that takes up an overall view of the room, no evidence was provided and that approach was later proved to be inaccurate. This paper presents a newly developed approach for measuring MRSE in a conventional cuboid space, simply by placing an illuminance meter at specific locations, recording the illuminance values caused by indirect light and calculating the weighted average of those values. The weighting parameters can be determined based on the geometry of the space. Furthermore, the rationality of such an MRSE-measurement method is provided, and its accuracy is verified by using Radiance lighting simulation, which suggests an error of less than 10%. Our proposed method shows that measuring MRSE in the field is feasible.

Study on mechanism of end face roof leaks based on stope roof structure movement under repeated mining

In view of the problem that the broken stope roof under repeated mining is prone to end face roof leaks, this paper’s research background is the close distance coal seams mining of a mine in Guizhou province, China. The impact of stope roof structure movement on the immediate roof was elucidated from the analysis of stope roof structure movement under repeated mining employing a combination method of field measurement, physical simulation, theoretical analysis, and numerical simulation. As a result, the mechanism of end face roof leaks under repeated mining is investigated, and the corresponding control measures are proposed. The results show that the cantilever beam structure instability of the stope roof under repeated mining is an important reason for the end face roof leaks and support crushing accident. The fracture forms of cantilever beam structure are divided into direct fracture and hinged structure fracture. The direct fracture is affected by the support working resistance. The cantilever beam hinged structure is divided into sliding and rotational instability. The periodic weighting interval is small and the fracture degree is large under repeated mining, which leads to the sliding instability. It is concluded that reasonable support working resistance is the important reason to keep the cantilever beam structure stability. Therefore, the stope roof leakage control countermeasures under repeated mining are proposed. The UDEC numerical simulation is used to verify the above analysis again, so as to provide the basis for the end face roof leaks prevention and control under repeated mining.

Fluvial sediment source to sink transfer at the Yellow River Delta: Quantifications, causes, and environmental impacts

Intensified human interventions in river basins and deltas lead to more complexities of environmental changes during the Anthropocene. Changes in river regime especially a dramatic reduction in sediment delivery increase challenges of the morphological and ecological sustainability of river deltas. In evaluating deltaic risks and sustainable solutions, researches are often limited to single geomorphic units of the deltaic system, and investigations of sediment source to sink transfer at river deltas under recent river regimes are often missing. The Yellow River Delta (YRD) presents as a typical megadelta under stressors induced by changing environments. This study utilizes a period of 20-yr high-resolution topography data of the deltaic channel and its subaqueous delta to investigate sediment transport and source to sink process by integrated methods of field measurements and numerical simulations. The results indicate that the deltaic channel has transitioned from net accretion to erosion after the implementation of the Water-Sediment Regulation Scheme (WSRS) in 2002. The active river mouth experienced a slow accretion phase since the river channel diverted to Qing 8 channel, with a reduced vertical deposition rate of 0.15 m/yr, whilst its adjacent Gudong littoral zone had a −0.11 m/yr erosion rate. Under the new fluvial regime, the river-borne suspended sediment tends to transport southwards to the Laizhou Bay, followed by the river-derived sediment transport eastward and northward to the offshore delta. It is clear that with the continued human activities in the region, the YRD is at the potential state of deltaic transition both in the deltaic channel and its subaqueous delta. This transition is believed to be beneficial to the deltaic channel stability, but it could significantly impact on the geomorphic and ecologic sustainability of the entire deltaic system.

Novel Method of Electromagnetic Field Measurements of the Human Brain.

IntroductionAdvancements in neuroimaging have changed the field of medicine. Computed tomography (CT) and magnetic resonance imaging (MRI) typically produce a static image of the brain, while continuous electroencephalogram (EEG) data is limited to the cortical surface. The brain’s chemical reactions produce an electric circuit that generates a magnetic field. We seek to test the ability of a non-contact sensor to measure the human brain’s electromagnetic field (EMF).MethodsA lightweight, inexpensive construct was designed to hold EMF sensors to non-invasively measure the human brain’s dynamic EMF. Measurements were conducted on non-clinical human volunteers. Background data without the human subjects was obtained, followed by introducing human subjects. Motionless human subject data was obtained, followed by a subject performing a task. Finally, a subject received auditory stimulation, and data was obtained.ResultsOur non-contact sensor was able to detect a difference between background activity without a human subject and the electromagnetic field of a human brain within the scalp and skull. Detectable differences in magnetic field potential were also obtained when the subject performed a task and received auditory stimulation.ConclusionIt is possible to continuously measure living human brain dynamic electromagnetic fields throughout the entire brain in a non-contact, non-invasive, continuous manner through the human scalp and skull in the standard environment. The signals are unique to the individual human and can be differentiated from background activity.

A Borehole Test for Chlorinated Solvent Diffusion and Degradation Rates in Sedimentary Rock

AbstractWe present a new field measurement and numerical interpretation method (combined termed “test”) to parameterize the diffusion of trichloroethene (TCE) and its biodegradation products (DPs) from the matrix of sedimentary rock. The method uses a dual‐packer system to interrogate a low‐permeability section of the rock matrix adjacent to a previously contaminated borehole and uses the borehole monitoring history to establish the pretest condition. TCE and its DPs are removed from the groundwater between the packers at the onset of the testing. The parameters estimated by fitting a radial diffusion model to the concentration history and borehole concentration data, also termed back diffusion, are the tortuosity factor and sorption coefficients of TCE and DPs in the rock matrix and the TCE and DP biodegradation rate coefficients in the borehole. We demonstrate the equipment design and the interpretive method using a borehole accessing the gray mudstone at a TCE contaminated site in the Newark Basin. In this test, both nonreactive (bromide) and reactive (trichlorofluoroethene) tracers are used to constrain the estimated parameters; however, the bromide tracer was not needed to estimate the parameters in this test. The parameters estimated from the field test are consistent with values measured independently in laboratory experiments using field samples of similar lithology. From the interpretation, we compute the TCE and DP concentration distributions in the rock matrix prior to the test to illustrate how the results can be used to enhance understanding of contaminant distribution in the rock matrix.

Study on thermal field and insulation measures of open-pit slope in alpine area

Taking the east slope at Lingquan open-pit mine as an example, the equation for determining the thickness of the insulation layer was deduced by adopting heat transfer theory. The field measurement and finite element method was used to research the insulation performance of polyurethane in the winter. The evolution law of slope temperature field under the conditions of insulation layer with or without insulation layer, different thickness, laying widths was analyzed. Through finite element method, the temperature evolution of slope covered by insulation layer with variable thickness and width at plates was analyzed. The results show that: the temperature variation of the insulation material measured by the field experiment and the finite element method is consistent; insulation layer effectively blocks the heat transmission from rock to the outside; as the thickness increases, the temperature increases nonlinearly, and the variability of which gradually decreases. There are differences in temperature variation at the slope top, surface, and toe, the temperature has an exponential relationship with width. The width of the insulation layer paved at plate effectively affects the temperature at the slope toe, the temperature tends to a fixed value with the width increasing.

Applicability of mobile-measurement strategies to different periods: A field campaign in a precinct with a block park

Urban green spaces play a crucial role in regulating the micro-climates of their surrounding built-up areas, which is particularly important in high-density cities. A field-measurement method with high accuracy and convenient movement is always adopted to assess the micro-climates and regulating capacity. Compared with fixed observation, mobile measurements have been found to offer advantages such as the need for lesser manpower and instruments. Despite the role of mobile measurements in characterizing urban thermal environments, there has still been a lack of consistent methods, leading to measurement errors. Accordingly, this study aimed to assess the applicability of mobile-measurement strategies by a two-day field campaign around People's Park in Guangzhou, China. Numerous findings were noted. Mobile measurements on the precinct scale required a staying time of at least 6 min to account for the response time of the probes. Additionally, the most applicable time periods for mobile measurements were the afternoon and even the evening. In terms of thermal characterization, the optimized reentry-transect method should be adopted for periods with abrupt changes in the ambient temperatures. Lastly, the block park has been observed to exert a more substantial ‘cool island’ effect under the colder weather on both days. Its park cooling intensity (PCI) in the late summer ranged from 0.55 to 1.82 °C, with a cooling efficiency of 0.33 °C/100 m, while that in the early autumn ranged from 0.49 to 3.18 °C, with a cooling efficiency of 0.50 °C/100 m.

Prediction and Treatment of Water Leakage Risk Caused by the Dynamic Evolution of Ground Fissures in Gully Terrain

Groundwater leakage in the loess gully terrain is one of the main hazards of coal seam mining at shallow burial depth. The burial depth of the 5−2 coal seam is less than 50 m from the ground in the gully of the study site. The fissures that expand upward after mining can easily penetrate the ground to form a water-conducting channels. During rainy periods, there is a potential risk of groundwater leakage. In order to reveal the characteristics of plane development and the dynamic evolution of gully ground fissures, the typical U-shaped gully in the northern Shaanxi coal mine was studied using the field measurement methods of “On-site measurement” and UAV aerial photography. Based on the experimental platform of ground fissure leakage developed and designed by the team, an indoor test model corresponding to the actual situation was established. In addition, the mathematical models of actual flood inrush, fissure width, and flood flow in the channel were established. The actual mine water flow and the mine drainage capacity were compared and analyzed, thus proposing criteria for classifying gully mining ground fissure collapsed water hazards. These criteria can provide theoretical references for predicting fissure leakage hazard zones in the ground gully of shallow buried coal seams. According to the development height of the water-conducting fissure zone (WCFZ), the treatment methods of ground fissures in gullies under different security conditions were designed, which was applied in the field with good results. The results showed that the treatment methods in this paper could effectively prevent the leakage of groundwater in the gullies along the ground fissures.

Development of a small-scale testing machine for use with interferometric monitoring methods

Material testing procedures are increasingly using image-based methods for strain field measurements, with extensive usage of Digital Image Correlation in particular. Nonetheless, there is interest in extending this use to other image-based interferometric methods with increased resolution, such as Electronic Speckle Pattern Interferometry (ESPI) and Shearography. In particular, ESPI requires very stable conditions for measurement, usually achieved by assembly on an optical table.Therefore, this work reports the development of a portable testing machine that can be assembled on INEGI’s optical table and is compatible with our previously developed 3D ESPI setup. The machine is an inexpensive custom design for static or quasi-static loading, with the main objective of withstanding a maximum load and velocity of 20 kN and 240 mm/min, respectively. The machine was built around a brushless dc motor and controller, both from Trinamic, and is currently being successfully used with ESPI methodology.

Image-based and in-situ measurement techniques for the characterization of the damage behavior of additively manufactured lattice structures under fatigue loading

For a safe application of additively manufactured (AM) lattice structures in e.g. load-bearing implants, a comprehensive understanding of fatigue processes is required. With additional systematic investigations of the underlying fatigue behavior, the AM lattice structure design as well as a reliable estimation of their lifetimes can be facilitated. Therefore, nondestructive testing methods, digitalization of measurement techniques as well as signal processing can be combined with experimental routines in order to aquire more information about the fatigue process. In this paper, different designs of Ti6Al4V lattice structures with cubic unit cells were fabricated by electron beam melting. To investigate the fatigue process as well as the underlying fatigue behavior the lattice structures were tested in cyclic bending as well as torsion tests. The digital image correlation technique, temperature field measurement and potential drop method were implemented into the test rigs and tested for the characterization of the fatigue damage behavior as well as failure mechanisms. To distinguish the failure behavior in dependence of manufacturing related imperfections a microstructural analysis was performed. Therefore, some experiments were stopped in dependence of the measured potential and examined in micrograph analysing. The successful application of the measurement techniques allows an insight into the damage behavior as well as underlying failure mechanisms of 3D printed lattice structures under fatigue loading. Moreover, the identified results provide the basis for the validation of subsequent numerical simulations using local damage approaches.

A Photographic Transect Method for Field Measurement of Vegetation Cover Along an Ecotone Gradient in a Desert Environment

A Photographic Transect Method for Field Measurement of Vegetation Cover Along an Ecotone Gradient in a Desert Environment

Dynamic Response Analysis of Super Shallow‐Buried Rectangular Tunnel

Relying on the project of the open‐cut municipal tunnel undercrossing Ankang Freight V yard, the train dynamic response and seismic response of ultrashallow‐buried rectangular tunnel of the lower interchange are studied, respectively, by combining the method of field measurement and numerical simulation. The results show that under the action of train vibration load, the dynamic stress response of the top plate midspan and the upper end of the side wall of the tunnel cross section directly below the rail is the most significant, and the dynamic stress response of the bottom plate is the smallest. Under the rare earthquake, the tunnel structure has large transverse deformation, in which the transverse displacement of the tunnel roof is the largest. At the same time, there is a large stress concentration at the variable section of the tunnel.

A Photographic Transect Method for Field Measurement of Vegetation Cover Along an Ecotone Gradient in a Desert Environment

A Photographic Transect Method for Field Measurement of Vegetation Cover Along an Ecotone Gradient in a Desert Environment