Large-scale Field Tests Research Articles

Cooperative Three-Dimensional Position Mapping Based on Received Signal Strength Measurements: Algorithm Design and Field Test

This paper presents a new approach to accurately and efficiently identifying a large number of wireless devices blindly installed to known three-dimensional installation/fitting points, based on received signal strengths (RSSs) between the devices. The approach is non-trivial because of the factorial, mapping nature of the considered problem, the multiplicative ranging errors of the RSS measurements (with standard deviation of 5–7 dB), and the requirement of high mapping accuracy in many internet-of-things (IoT) applications, e.g., industrial IoT and aircraft. The consideration of a structured environment where the set of candidate node positions is known beforehand shifts the problem of interest from a pure position estimation problem to a position assignment problem. The key idea of the proposed approach is that we interpret the position mapping problem with a probabilistic graphical model, where the factorial nature of mapping (more specifically, the mutual exclusiveness of devices at every installation point) is fully captured. A max-product belief propagation is designed against the probabilistic graph, to estimate the max-marginal position distribution of each device. The Kuhn-Munkres algorithm is applied to preserve the mutual exclusiveness of devices throughout the belief propagation and to decide device locations based on the estimated position distributions. Large-scale simulations and field tests are carried out, showing that the new approach achieves close-to-100% accuracy in simulations with hundreds of blindfolded devices under RSS measurement errors with standard deviation of 5–7 dB. Our approach also achieves 100% accuracy in all field trials with 76 devices inside the cabin of a Fokker 100 airplane, dramatically outperforming baseline techniques.

Numerical Simulation Study on Heat Transfer Mechanism of Excavation Based Enhanced Geothermal System

The innovative excavation based EGS (EGS-E) scheme uses mining techniques to form deep underground access for creating artificial heat reservoir with multi-level fracture networks using excavation, blasting, and caving. The two-level heat transfer mechanism of distributed artificial heat reservoir has a dominant influence on the performance of excavation based Enhanced Geothermal System(EGS-E). However, due to the large-scale field testing and laboratory physical experiment are not yet realistic, the process of natural convection heat transfer within the surrounding rock enhanced permeability and water filled zones hasn’t been effectively studied. The simulation software COMSOL Multiphysics was used to numerically simulate the natural convection heat transfer within the enhanced stimulated surrounding rock around a single straight roadway with its circular opening, which should be an elemental unit for mining heat in deep underground engineering structure. The simulation results demonstrated that the temperature difference inside the surrounding rock of a roadway causes the density of working fluid to vary. Driven by buoyancy, the natural convection of working fluid occurs in the surrounding rock. It enhances the heat transfer inside hot dry rock, and its efficiency is significantly more remarkable than that of the conduction through hot dry rock itself, which can improve the efficiency of heat recovery with regards to EGS-E. Due to the low solid heat conduction efficiency of the surrounding dry hot rock, adjusting the speed of the water flow inside the pipe can effectively control the temperature of the water outlet to improve the heat collection life of the system.

Controlling microbial activity on walls by a photocatalytic nanocomposite paint: A field study

Bacteria and fungi that grow on the walls can cause allergic reactions and infectious diseases in human. We proposed a low-cost and easy-to-operate testing protocol for large scale field studies to evaluate the long-term antimicrobial performance of a novel WOx paint in 2 primary schools. In Tun Mun and Tin Shui Wai schools, WOx paints were painted on semi-outdoor and indoor walls and daily chlorine disinfection was applied after class in TSW School. A guidance was proposed for the protocol using the ATP biofluorescence method for large-scale field studies. ATP swab samples were taken at locations with and without the WOx paint on a control basis with a sampling frequency once a week for three months. The ATP values were then processed and presented in box plots. In both schools, the median log-scale ATP values of walls with WOx paint were at least 0.5-log lower than those without WOx paint. The WOx paint also performed better than daily chlorine disinfection in reducing microbial activities in long-term. The proposed testing protocol is suitable to evaluate long-term performance of an antimicrobial paint by analyzing its microbial activity in large-scale field tests. The WOx paint shows long-term effectiveness in reducing microbial activities on wall surfaces in both indoor and semi-outdoor environments.

Development and validation of an instrument to assess Chinese upper-level elementary students’ attitudes towards science

ABSTRACT The aim of this study was to develop an instrument to measure upper-level Chinese elementary students’ attitudes towards science by addressing problems with existing ones, as highlighted in the literature. The theoretical framework was drawn from the ABC model, which defines attitudes towards science as consisting of affective, behavioural, and cognitive domains in the study. Instrument development was performed through expert review, small-scale pilot tests and student interviews, large-scale field tests and validation. Factor analysis and Rasch analysis provided reliability and validity evidence. According to the results of the first round of the field test, changes were made to the items and the response category in the second round of the development procedure. The final instrument demonstrated good psychometric properties and consisted of four dimensions: enjoyment of science learning, self-efficacy in science learning, value of science learning and intention to learn and do science.

Preparation of superhydrophobic paper mulch and study on its anti-UV performance

In order to improve the shortcomings of paper mulch, such as the low water resistance and weather fastness in practical application, the paper mulch with a superhydrophobic structure was prepared by depositing zinc oxide layer and silicon dioxide layer on the surface of paper mulch by the solution impregnation method, the paper mulch surface treatment method is simple and environmentally friendly. The surface chemical composition and surface morphology of paper mulch before and after UV aging were characterized, respectively. The wetting property, bouncing property, and mechanical stability of paper-based film were studied. The results showed that the static contact angle of the superhydrophobic paper mulch was as high as 161.77°, and the average sliding angle was only 3.5°, which also showed excellent droplet bounce performance and mechanical stability. After UV aging experiment, the static contact angle of super-hydrophobic paper mulch was increased to 163.64°, and the sliding angle was reduced to 2.5°. Its excellent performance could still be maintained, showing excellent UV resistance, which improved the weather fastness and water resistance of paper mulch to a certain extent, and laid a foundation for the next large-scale field test.

Large-Scale Field Test Study on Failure Mechanism of Non-Cohesive Landslide Dam by Overtopping

In recent years, landslide lake disasters occur frequently in southwest mountainous areas of China. Considering the influence of dam size and discharge channel location, three large-scale field tests were carried out in a natural river to study the failure process and mechanism of non-cohesive soil landslide dam, and the process and mechanism of non-cohesive landslide dam breach were analyzed. The results show that the dam size and discharge channel location have a significant influence on the breach mechanism of the landslide dam. The dam failure process can be divided into three stages: the initiation stage, the development stage and the failure stage. When the discharge channel is located close to the bank, the width of the breach is smaller, and the volume of the residual dam body is larger. The more stable the dam body is, the longer the breach process time is, and the smaller the peak discharge is. This study can provide a scientific reference for the emergency disposal and risk assessment of landslide dam.

Numerical modelling of geotextile tubes filled with gold mine tailings

Geotextile tubes are generally used in hydraulic and marine applications such as coastal protection and flood control. They are also used to dewater sludge from sewage treatment plants and dredged materials. Studies have been carried out to derive analytical solutions and develop empirical models as well as numerical simulations to represent the behaviour of geotextile tubes in such applications. However, there has been insufficient attention on dewatering of mining tailings. This article presents the numerical results of modelling a geotextile tube using Abaqus, a commercially available finite element software package. The mechanical behaviour of the tube was simulated while it was being filled with gold mining tailings. Back analyses of a large-scale field test as well as parametric analyses were performed to evaluate the influence of filling pressure, elastic modulus and finite element type on the stress–strain behaviour of the geotextile tube. In terms of validation, the numerical results agreed well with the analytical results and field test observations. A smaller elastic modulus causes greater strain. Comparing the results obtained using different types of finite elements, it was observed that the membrane element used to simulate the geotextile tube represented its mechanical behaviour well.

Development of Pop-up Book Mathematics Learning Media on Polyhedron Topics

One of the difficulties of students studying the polyhedron topics is the visualization of the objects so that a learning media that can help and motivate students in learning polyhedron is needed. This research aims to develop a mathematics learning media in the form of a pop-up book to help students learn the material of polyhedron. This research is a development research that uses the Borge & Gall method, which consisted of several procedures as follows: (1) analysis of the to-be-developed product; (2) first product development; (3) validation and revision; (4) large-scale field tests; and (5) the final product. The subjects of this research were 30 students of 8th grade Sunan Kalijaga Malang Junior High School. The pop-up book media developed was declared as valid and received an excellent response from students. Teachers are advised to use a pop-up book media in polyhedron learning.

PENGEMBANGAN MEDIA PANLINTARMATIKA (PAPAN PERKALIAN PINTAR MATEMATIKA) MATERI PERKALIAN UNTUK SISWA SEKOLAH DASAR

This study aims to 1) find out the steps in developing Panlintarmatika learning media, 2) know the feasibility of developing Panlintarmatika learning media based on experts. This study is a type of Research and Development (RD) research using the Borg and Gal model which consists of: (1) research and information collecting, (2) planning, (3) developing preliminary from a product, (4) prelimunary field testing, (5) main product revision, (6) main field testing, (7) operational product revision (8) operational field testing. The trial subjects used were 18 grade 2 students and teachers at SD N Kalangan. Data collection techniques in the form of observation, interviews and questionnaires. Data analysis includes quantitative data analysis and qualitative data analysis. The results showed that the validation of the media experts received a score of 60 in the "Very good" category, the validation of the material experts received a score of 42 in the "Good" category and the learning expert received a score of 60 in the "Good" category. The results of the small-scale field test students get a score of 100 with the category "Very Good" and the teacher gets a score of 94 with the category "Very Good". Large-scale field test results students get a score of 100 with the category "Very Good" and the teacher scores 98 with a score of "Very Good" It can be concluded that the Panlintarmatika learning media is feasible and can be used as class 2 learning multiplication material

On mechanical behaviour of clastic soils: numerical simulations and constitutive modelling

Clastic soil is ubiquitous in practice but still poses a challenge for testing and modelling. Conventional laboratory tests with small sizes are not suitable for the large grain size, while large-scale tests and field tests are often too costly and time-consuming. In this paper, the mechanical behaviour of clastic soil is described by a hypoplastic constitutive model based on numerical simulations considering both the soil matrix and breccia. The numerical simulations indicate that the breccia content, gradation and the overconsolidation ratio have a significant influence on the strength, deformation and failure pattern of the clastic soil. The coarse particles are found to change the stress path developed in the soil matrix and consequently influence the critical state of the soil matrix. Moreover, the coarse particle distribution based on computed tomography scanning seems to have a larger impact than the breccia content on the failure pattern of clastic soils.

Plant growth-promoting microbes - an industry view.

Plant growth-promoting microbes can affect the plant microbiome, improving different properties of the plant such as yield and health. Many companies are commercializing these microbes as products called biologicals. Defining the product concept is one of the first and most important steps in making a biological product. Companies can use phenotyping and genotyping approaches to identify the microbe to make into a live bacterial product. Screening usually begins in the laboratory and often moves from high-throughput methods to more time and resource-intensive methods culminating in large scale field testing. Once the microbe is chosen, the fermentation process grows the bacteria to the necessary amounts, while the formulation process ensures a stable product in the desired form such as a liquid or powder. The products must show yield increases in the field over several seasons and conditions, but also must be easy to use and cost-effective to be adopted by farmers and other customers. Tying all these data together from the selection process to test results gives a customer a 'reason to believe' for the marketing and launch of a successful product.

A Study on Relationship among Blade Camber Direction and Pitch Angle and Performance of a Small Straight-Blade Darrieus Wind Turbine by Using Scale Test Model and Gurney Flap

Straight-blade Darrieus vertical axis wind turbines are used as medium and small size wind turbine because of higher power output in vertical axis wind turbine (VAWT). In our previous study, the relationship between the performance and Reynolds number based on airfoil chord length had been investigated by using small-scale test models of lift-type VAWT, and the results showed that the performance of tested wind turbine models with small diameter was clearly lower than that of the large-scale field test machine, and its performance also varies significantly with the blade pitch angle. In this study, we focused on the performance of a small-scale straight-blade Darrieus VAWT, the relationship among the blade airfoil camber direction and the pitch angle, and the performance of the small-scale VAWT was examined experimentally by using a small-scale VAWT test model with Gurney flap which was a small flat plate. Gurney flaps with its height h, as a ratio to the blade chord length c, h/c = 0.036 to 0.055, were attached to the blades of the VAWT test model, in addition, the attaching direction of the Gurney flap on the blade was examined for both inward and outward of the rotor, and the pitch angle was also examined for a range of −5 to 10 degrees. These results are discussed comparing with the result of the VAWT without Gurney flap and considering the numerical results for the single blade with/without the Gurney flap. The results showed that the performance of the tested VAWT was reversed between the inward and outward Gurney flaps around a pitch angle of 10 degrees. That is, the inward Gurney flap was superior at a pitch angle of less than 10 degrees, while the outward Gurney flap was effective at a pitch angle of more than 10 degrees. Furthermore, for the tested small-scale VAWT model, the optimum pitch angle was about 5 degrees, and the inward and shorter Gurney flap showed higher power performance of the VAWT under this pitch angle condition.

A Statistical Approach Toward Channel Modeling With Application to Large-Scale Censored Data

Connected vehicle safety and efficiency applications rely on vehicular wireless networks for information sharing. To study the performance of these networks, and numerous protocols designed for them, it is essential to be able to model the channel behavior. However, due to the complexity of the vehicular environment, such modeling has to rely on data collected from large scale field tests. A majority of data collection campaigns with a large number of vehicles utilize vehicular on-board units (transceivers) to collect data in the form of received signal strength (RSS) values. Such datasets are limited in information since only the RSS values of correctly received packets are recorded, leading to datasets that can be considered as censored; especially where packet losses are high. Therefore, deriving channel models that accurately represent the channel behavior at distances with considerable loss of packets is a challenge. In this paper, we propose Bernoulli Mapping Estimation, a novel approach for the estimation of distributions from censored samples. Additionally, we provide a general method and formulation for modeling the communication channel in vehicular environments, considering receiver characteristics, imperfections, and data sparsity. The proposed methods were applied to datasets collected from highway and intersection environments; and the derived models are shown to be accurate representations of the datasets. It is also shown that even with only a small fraction of the RSS values, the framework is able to produce fading models that are similar in characteristics to field data.

Bioremediation of oily sludge by solid complex bacterial agent with a combined two-step process

In the present research, a bioremediation process was developed using solid complex bacterial agents (SCBA) through a combined two-step biodegradation process. Four isolated strains showed high efficiency for the degradation of total petroleum hydrocarbons (TPH) and the reduction of COD of the oily sludge, at 96.6% and 92.6%, respectively. The mixed strains together with bran prepared in form of SCBA exhibited improved performance compared to individual strains, all of which had an optimal temperature of around 35 °C. The use of SCBA provided advantages over commonly used liquid media for storage and transportation. The two-step process, consisting of firstly biosurfactant-assisted oil recovery and secondly biodegradation of the remaining TPH with SCBA, demonstrated the capability for treating oily sludge with high TPH content (>10 wt%) and short process period (60 days). The large-scale (5 tons oily sludge) field test, achieving a TPH removal efficiency of 93.8% and COD reduction of 91.5%, respectively, confirmed the feasibility and superiority of the technology for industrial applications.

Content Validity of the LIMB-Q: A Patient-Reported Outcome Instrument for Lower Extremity Trauma Patients.

Limb-threatening lower extremity traumatic injuries can be devastating events with a multifaceted impact on patients. Therefore, evaluating patient-reported outcomes (PROs) in addition to traditional surgical outcomes is important. However, currently available instruments are limited as they were not developed specific to lower extremity trauma patients and lack content validity. The LIMB-Q is being developed as a novel PRO instrument to meet this need, with the goal to measure all relevant concepts and issues impacting amputation and limb-salvage patients after limb-threatening lower extremity trauma. This is a qualitative interview-based study evaluating content validity for the LIMB-Q. Patients aged 18 years and older who underwent amputation, reconstruction, or amputation after failed reconstruction were recruited using purposeful sampling to maximize variability of participant experiences. Expert opinion was solicited from a variety of clinical providers and qualitative researchers internationally. Preliminary items and scales were modified, added, or removed based on participant and expert feedback after each round of participant interviews and expert opinion. Twelve patients and 43 experts provided feedback in a total of three rounds, with changes to the preliminary instrument made between each round. One scale was dropped after round one, one scale was added after round two, and only minor changes were needed after round three. Modifications, additions and removal of items, instructions, and response options were made after each round using feedback gathered. The LIMB-Q was refined and modified to reflect feedback from patients and experts in the field. Content validity for the LIMB-Q was established. Following a large-scale field test, the LIMB-Q will be ready for use in research and clinical care.

Coupled numerical simulation of a flexible barrier impacted by debris flow with boulders in front

Flexible barriers have been widely adopted to mitigate the debris flow disasters. However, the research on the coupled interaction analysis between flexible barriers and debris flows with boulders in front is rarely reported. In this paper, a two-stage coupled modeling technique which can account for the debris mobility, the non-linear behavior of a flexible barrier, and the dynamic interaction between flexible barriers and debris flows is developed firstly based on the Arbitrary Lagrangian-Eulerian (ALE) method using LS-DYNA. The proposed coupling model is verified by a large-scale field test, comparing the flow velocity and flow depth of the debris flow, as well as the internal force and deformation of the flexible barrier. Further, the proposed numerical model is adopted to study the performance of flexible barrier impacted by debris flow with boulders in front. Two practical cases that the debris flow contains a single boulder with a diameter of 2 m and 1 m in front, respectively, are investigated. The impact positions are both the bottom center of the middle functional module of the barrier. The numerical results show that the barrier cannot intercept the debris flow with a boulder of 2 m in diameter. When the flexible barrier is subjected to three 1 m boulders in front of the debris flow, plastic hinges are formed at impact positions of the steel posts. It is recommended that additional protection measurements are required to maintain the structural integrity.

Real-time topological localization using structured-view ConvNet with expectation rules and training renewal

Mobile service robots possess high potential of providing numerous assistances in the working areas. In an attempt to develop a mobile service robot which is dynamically balanced for faster movement and taller manipulation capability, we designed and prototyped J4.alpha, which is intended for swift navigation and nimble manipulation. Previously, we devised a pure visual method based on a supervised deep learning model for real-time recognition of nodal locations. Four low-resolution RGB cameras are installed around J4.alpha to capture the surrounding visual features for training and detection. As the method is developed for ease of implementation, fast real-time application, accurate detection, and low cost, we further improve the accuracy and the practicality of the method in this study. Specifically, a set of expectation rules are introduced to reject outlier detections, and a scheme of training renewal is devised to effectively react to environmental modifications. In our previous tests, precision and recall rates of the location coordinate detection by the ConvNet models were generally between 0.78 and 0.91; by introducing the expectation rules, precision and recall are improved by approximately 10%. A large scale field test is also carried out here for both corridor and factory scenarios; the performance of the proposed method was tested for detection accuracy and verified for 2 m and 0.5 m nodal intervals. The scheme of training renewal designed for capturing and reflecting environmental modifications was also proved to be effective.

Alkali Effect on Alkali-Surfactant-Polymer (ASP) Flooding Enhanced Oil Recovery Performance: Two Large-Scale Field Tests’ Evidence

Alkali-surfactant-polymer (ASP) flooding is very promising chemical enhanced oil recovery (EOR) technology which can make an incremental oil recovery factor (IORF) of 30% original oil in place (OOIP). How to choose alkali in ASP flooding remains a question for a long time. As the world’s only and largest ASP flooding application place, Daqing Oilfield has always adhered to the strategy of parallel development of strong alkali ASP flooding (SASP) and weak alkali ASP flooding (WASP), but SASP is in a dominant position, indicated by more investments and more project numbers. This leaves an impression that SASP is better than WASP. However, WASP is drawing more interest than SASP recently. Moreover, as the ASP flooding in Daqing went from field tests to commercial applications since 2014, how to comprehensively consider the benefit and cost of ASP flooding has become a new focus at low oil prices. This paper compares two typical large-scale field tests (B-1-D SASP and B-2-X WASP) completed in Daqing Oilfield and analyzes and discusses the causes of this difference. The injection viscosity and interfacial tension (IFT) for the two field test areas are substantially equivalent under the conditions of Daqing Oilfield, and WASP is better than SASP when reservoir geological conditions are considered. WASP exhibits the same IORF of 30% as SASP while having a much better economic performance. For the SASP field test, the injected strong alkali NaOH makes the test behave unlike a typical strong ASP flooding due to the presence of CO2 in the formation fluid, which well explains why IORF is much higher than all the other SASPs but scaling is less severe than others. This paper confirms that under Daqing Oilfield reservoir conditions, it is the alkali difference that caused the performance difference of these two tests, although some minor uncertainties exist. WASP is better than the SASP providing the same conditions . In addition, the detailed information of the two ASP field tests provided can give reference for the implementation of ASP flooding in other oilfields. After all, the study of ASP flooding enhanced oil recovery technology under low oil prices requires great foresight and determination.

Recent Advances of Surfactant-Polymer (SP) Flooding Enhanced Oil Recovery Field Tests in China

Recently, there are increasing interests in chemical enhanced oil recovery (EOR) especially surfactant-polymer (SP) flooding. Although alkali-surfactant-polymer (ASP) flooding can make an incremental oil recovery factor (IORF) of 18% original oil in place (OOIP) according to large-scale field tests in Daqing, the complex antiscaling and emulsion breaking technology as well as potential environment influence makes some people turn to alkali-free SP flooding. With the benefit of high IORF in laboratory and no scaling issue to worry, SP flooding is theoretically better than ASP flooding when high quality surfactant is available. Many SP flooding field tests have been conducted in China, where the largest chemical flooding application is reported. 10 typical large-scale SP flooding field tests were critically reviewed to help understand the benefit and challenge of SP flooding in low oil price era. Among these 10 field tests, only one is conducted in Daqing Oilfield, although ASP flooding has entered the commercial application stage since 2014. 2 SP tests are conducted in Shengli Oilfield. Both technical and economic parameters are used to evaluate these tests. 2 of these ten tests are very successful; the others were either technically or economically unsuccessful. Although laboratory tests showed that SP flooding can attain IORF of more than 15%, the average predicted IORF for these 10 field tests was 12% OOIP. Only two SP flooding tests in (SP 1 in Liaohe and SP 7 in Shengli) were reported actual IORF higher than 15% OOIP. The field test in Shengli was so successful that many enlarged field tests and industrial applications were carried out, which finally lead to a commercial application of SP flooding in 2008. However, other SP projects are not documented except two (SP7 and SP8). SP flooding tests in low permeability reservoirs were not successful due to high surfactant adsorption. It seems that SP flooding is not cost competitive as polymer flooding and ASP flooding if judged by utility factor (UF) and EOR cost. Even the most technically and economically successful SP1 has a much higher cost than polymer flooding and ASP flooding, SP flooding is thus not cost competitive as previously expected. The cost of SP flooding can be as high as ASP flooding, which indicates the importance of alkali. How to reduce surfactant adsorption in SP flooding is very important to cost reduction. It is high time to reevaluate the potential and suitable reservoir conditions for SP flooding. The necessity of surfactant to get ultra-low interfacial tension for EOR remains further investigation. This paper provides the petroleum industry with hard-to-get valuable information.

Three-dimensional velocity and concentration measurements and simulations of a scaled Jack Rabbit II mock urban array

Abstract Magnetic resonance (MR) techniques provide non-invasive, three-dimensional measurements of velocity and concentration fields. Applying MR techniques to measure flows of contaminants through urban arrays provides a wealth of information that is difficult to obtain with large-scale field tests. In this project, a 1:188 scaled model of the phase 1 Jack Rabbit II field test was replicated and studied using a water tunnel with properties chosen to mimic field conditions. Three-dimensional, time-averaged flow data was measured using magnetic resonance velocimetry (MRV) and magnetic resonance concentration (MRC) techniques. The scaled flow was also modeled with large-eddy simulations (LES) to provide a dataset for comparison with the MR based measurements. Despite a complex, three-dimensional flow field, both velocity and concentration show good agreement between the experimental measurements and simulation data. Measurement uncertainty was estimated to be ± 5 % of each of the measured velocity components at each location for MRV and ± 4 % of the measured concentration at each location for MRC.