Field Operational Conditions Research Articles

Predictive Diagnosis in Axial Piston Pumps

Increasing reliability, availability and safety requirements as well as an increasing amount of data acquisition systems have enabled condition-based maintenance in mobile and industrial machinery. In this paper, we present a methodology to develop a robust diagnostic approach. This includes the consideration of variable operating conditions in the data acquisition process as well as a versatile, non domain-specific feature extraction technique. By doing so, we train anomaly detection models for different fault types and different fault intensities in variable displacement axial piston pumps. Our specific interest points to the investigation of high-frequency condition indicators with a sampling rate of 1 MHz. Furthermore, we compare those to industry standard sensors, sampled with up to 20 kHz.By considering variable operating conditions, we are able to quantify the influence of the operating point. The results show, that high-frequency features are a suitable condition-indicator across several operating points and can be used to detect faults more easily. Although set up on a test-bench, the experimental design allows to draw conclusions about realistic field operational conditions.

Stochastic mechanistic modelling of two-phase slug flow forces on bends in horizontal piping

Slug flow through piping systems may cause severe mechanical vibrations. Finite element models, commonly used to predict dynamic pipe stresses and fatigue, require the slug excitation force as boundary condition.In this paper, a stochastic mechanistic model of the slug force acting on a pipe bend is proposed. The force induced by continuous hydrodynamic two-phase slug flow is modelled by the momentum balance over the bend using slug quantities as liquid holdup and phase velocity. The two-phase flow is described by a train of slug units. Each unit is divided into a film zone with a constant liquid height and a slug zone with aerated liquid. Two-phase flows have a stochastic character, but models based on a fixed slug length cannot predict stochastic force variations. A new approach is introduced that includes the stochastic character of slug flow in the force calculations. A unit slug model is adapted with a log-normal distribution as closure for the slug zone length, resulting in an improved model with stochastic properties. A Lagrangian approach is used to solve the governing equations.Results of the new model are compared with bend force measurements found in the literature. Most of the published measurements were done with air and water under atmospheric conditions. In many field applications, the fluids and operational conditions are different from those used in laboratory experiments. The stochastic mechanistic approach, where the main equations are based on physical laws, increases the models applicability outside the atmospheric air and water conditions used for the validation.

Gyroscopic Effect in Machine Working Assemblies

Abstract This paper discusses and calculates the impact of the gyroscopic effect on the increase in the agricultural machine working assemblies’ load on bearings of the chaff cutter type. This effect occurs under natural field operational conditions of this type of machine either during the change in direction of its movement or moving over irregular surface and is caused by a sudden change in the axis direction of quickly rotating masses. In a form of graph, there is a presentation of a mathematical model and exemplary results of simulation calculations for selected parameter values related to the movement and operation of machines with a high-speed drum. Calculations were conducted on the basis of analysis of technical data of working machines of the chaff cutter type. Conducted analysis of the agricultural machine working assemblies’ load on bearings showed that these loads may temporarily increase even by ten times in case of the machine turn and eight times in case of moving over irregular of surface, considerably influencing their lifetime.

Impact of Aeration on the Removal of Organic Matter and Nitrogen Compounds in Constructed Wetlands Treating the Liquid Fraction of Piggery Manure

The increasing demand for sustainable, robust and cost-efficient wastewater treatment techniques strengthen the implementation of constructed wetlands (CWs) in the agricultural sector. In countries like Belgium (Flanders), the compliance of strict water quality standards and surface area requirements have hindered considerably their application. New wetland designs such as aerated CWs, could help to overcome these challenges. This study evaluated the capacity of artificially aerated mesocosm systems to decrease chemical oxygen demand (COD) concentrations below the 125 mgO2/L limit imposed on installations treating animal manure. The treatment of this high-strength wastewater has been slightly studied via aerated CWs. A three-stage experiment investigated the effect of constant, intermittent and non-aeration regimes on: ammonium volatilisation, the evolution of organic and nitrogen compounds concentrations, and denitrification. The results were assessed through a mixed modelling procedure using SAS 9.4 software. A COD removal between 65% and 58% in constantly and intermittent aerated systems, versus 27% COD removal in the non-aerated system indicated the effectiveness of aeration. However, a dissimilarity was encountered in the removal of nitrogen compounds, resulting in an 82% decrease of nitrate concentrations in the non-aerated system, versus 0.5% and 11% in the aerated ones. Based on the results, this experimental set-up adjusted to field operational conditions can prove that aerated CWs can treat the liquid fraction of piggery manure.

Endoscopy and Cannulation as Non-Invasive Tools to Identify Sex and Monitor Reproductive Development in Arapaima gigas

The lack of tools for sex identification and assessment of gonadal development are hindering our ability to study the reproductive dysfunction of Arapaima gigas in captivity. This study initially aimed to validate a non-surgical endoscopy procedure to identify sex in juveniles and assess stage of ovary development in female broodstock under field operational conditions. Cannulation, assisted through the description of the genital anatomy, made ovarian biopsy possible to describe oocyte development from primary growth to pre-ovulation, providing a first classification scheme for oogenesis in the species including description of the micropyle morphology using scanning electron microscopy. Cannulation was also successfully performed without endoscopic guidance, which allowed monitoring of ovarian development along the reproductive season together with profiling of plasma sex steroids (17β-estradiol [E2] and 11-ketotestosterone [11-KT] in females and males, respectively). The monitoring of our study population showed females paired with males in earthen ponds sexually matured and reached oocyte maturation during the spawning season. However, since no spawning was recorded, eggs had either been resorbed or released and not fertilized by the male. Plasma E2 levels remained high in females, as expected in an asynchronous species during the spawning season with multiple batches of oocytes being recruited. Plasma 11-KT showed a tendency to decrease, suggesting a male reproductive dysfunction or the end of the reproductive season with a lack of synchronization between sexes. In conclusion, endoscopy and cannulation are tools that can be promptly applied to aid sex identification, assessment of reproductive function, and overall broodstock management in wild and captive stocks. These tools will greatly help future studies looking at the effects of environmental, social, and hormonal cues on reproductive development with the aim of developing a spawning induction protocol for the species.

Design for Reliability Analysis of Vibration-Induced Failures due to Equipment Assembly Bending Load and Vibration Responses

Abstract The oil and gas industry subsurface formation evaluation instruments experience significant challenging vibrations and shock levels. Equipment development requirements for these instruments include reliability and durability under these severe operating conditions. The engineering design for this equipment utilizes tools that enable the estimation of service lifetime, maintenance cycles, and related costs. These engineering tools model failure modes and their acceleration factors and how failures interact under certain circumstances. Laboratory test data and operations failure history are used to validate the model results. Incorporating equipment operational failure history into the reliability design after failure analysis, enables determination of failure modes and the length of stress level exposure. Before the equipment is commissioned to field operational service, it is subjected to a batch of environmental qualification tests under objective pass-fail criteria. The environmental qualificat...

Application of fibre sensor in grain drill to estimate seed flow under field operational conditions

A new sensing system to estimate the mass flow of seeds in the grain drill was developed and evaluated in this paper. This was a manipulation of an estimation model developed indoors using fibre sensors; by considering the operational conditions of the machine and environment. Therefore, an original method to install the sensor within the grain drill was tried, and modifications on the estimation model and algorithm were performed.The experiment to test and evaluate the sensing system consisted of running a grain drill-propelling tractor in the farm of Hokkaido University several times to sow rye seeds, where each run was approximately 160m. Two fibre sensors were installed at two different metering units, that use axial flute rollers, inside the grain drill. Also, the seeds being discharged during the experiment were collected and weighed at the end of each run. The results of 52 trials to estimate the mass flow of seeds indicated that in approximately 98% of the trials the estimation rate exceeded 90%. Moreover, the overall estimation rate was approximately 95%. These results seemed not to be biased by the change of the sensor set nor the sensing location.The modifications on the estimation model were successful in eliminating the overestimation or underestimation bias that resulted by changing the speed in the indoor experiments. In addition, the modifications on the estimation algorithm could eliminate error in the sensor output values that may result from dust, vibration, or variation in the sensor internal resistance. These results showed that the sensing system can be used practically to monitor the seed flow in the grain drill which would have many applications in precision agriculture practices.

Milling recovery and quality of combine harvested paddy: a case study in Batticaloa and Ampara Districts

Grain quality directly affects the profitability of a crop. This study investigated the field operational conditions of combine harvesters with respect to the quality of the grain. A total of six brands of combine harvesters were tested in 10 different fields in Batticaloa and Ampara districts. The damages imposed on grains were determined based on the milling quality of the samples. The holistic view of data from farmers’ field trials indicated that the combine forward speed, tip velocity of threshing drums and grain moisture content highly influenced the physical damages caused to the paddy grains during milling. Threshing unit tip velocity of the combine harvesters were found to be in the range of 10.35 – 39.51 m/s. The tip velocity of 10.35 m/s gave the lowest broken percentage of 15.38% and a higher head rice yield of 49.45%. Relatively low percentages of broken rice of 19.32% and 27.45% were obtained at high forward speeds of 1.36 and 2.5 m/s, respectively. This could be due to the creation of cushioning effect on the grains by increasing feed rate. High impacting forces on the grains at increased tip velocities caused the grain fissures which decreased the quality of seed paddy. The lowest grain moisture content of 15.9% yielded a relatively high broken rice percentage of 33.98 kg/ha at the tip velocity of 24.64 m/s. The highest grain damage of 39.94 kg/ha was obtained during milling at the tip velocity of 39.51 m/s at the moisture content of 20.9%. Tropical Agricultural Research Vol. 26 (1): 120 – 130 (2014)

Orifice plate meter field performance: Formulation and validation in multiphase flow conditions

The performance of orifice plates in real-time monitoring of oil, gas and water standard flow rates was investigated. To this end, a multi-rate test was implemented in two production wells routed individually to a test separator in field operational conditions. The well flow rate was varied in steps by changing the choke opening.The ranges of fluid properties and flow conditions achieved during the experiment were: wellhead pressure from 9073kPa to 13,278kPa, wellhead temperature from 47.8°C to 53.5°C, downstream choke pressure from 6770kPa to 7913kPa, downstream choke temperature from 41.6°C to 49.1°C, gas–oil-ratio from 1144Sm3/Sm3 to 2068Sm3/Sm3, water-cut from 4.64% to 58.35%, standard oil specific gravity from 0.7988 to 0.8058, standard gas specific gravity from 0.7340 to 0.7550, standard oil flow rate from 46.86Sm3/d to 266.65Sm3/d, standard gas flow rate from 62.68×103Sm3/d to 296.65×103Sm3/d, standard water flow rate from 18.06m3/d to 159.33m3/d.The wells tested showed a different dynamic behavior: while well #2 did not vary significantly the stream composition with flow rate, well #1 produced under gas coning, a near well-reservoir phenomenon that governs the contribution of the reservoir gas-cap to the total stream composition.The multi-rate tests generated two data sets with 1424 flow conditions through two flange-tap orifice plates installed upstream (wellhead) and downstream of a cage choke valve. The ranges of orifice variables were: orifice diameter from 0.03479m to 0.0430m, beta factor from 0.4946 to 0.6507, differential pressure from 15kPa to 187kPa.The virtual metering system presented in Paz et al. (2010) was used to correlate the experimental data. The associated model, suitable for differential pressure measuring devices, includes effects such as flow concentration and slip (through Chisholm’s correlation), generalizing the mass flow rate versus pressure drop relationship for multiphase flow. The total mass flow rate depends on a set of variables evaluated at metering conditions: density and viscosity of the liquid and gas phase, mass quality, pressure drop across the flow meter and geometry (contraction area and beta factor).The determination of the fluid properties at metering conditions was made by using black-oil correlations. These correlations are based on a set of input variables at standard condition that characterizes the stream composition such as gas–oil ratio, water–oil ratio and specific gravities of each phase.A comparison was made between the multiphase flow rates predicted by the model and the ones simultaneously measured at the test separators. The oil, gas and water standard volumetric flow rate deviations (coefficients of variation of the root mean square deviations) were below 3.52%.It was theoretically demonstrated and experimentally verified that a systematic error exists when the homogeneous model (equal phase velocities) is considered in the formulation, resulting in a flow rate underestimation. When the homogeneous model was used to correlate the data, this effect increased the deviation up to 10.5%.Flow pattern at the wellhead was characterized as intermittent and annular-mist. Lockhart–Martinelli parameter varied from 0.362 to 0.836; despite of the experimental data being beyond the wet gas region, the multi-rate tests showed that Chisholm’s over-reading can be successfully extrapolated to these range.

Performance evaluation and engineering considerations for a modular- and culvert-based paddlewheel circulator for split-pond systems

The split-pond system (SPS) has been proposed as an alternative culture method to increase the efficiency of pond aquaculture production. This study evaluated the performance and the engineering models of paddlewheel circulators on commercial catfish SPSs.The power requirement and the water flow rate by the circulators increased as the rotational speed and water depth in the culvert increased. The rotational speed increased the power requirement exponentially and the water flow rate linearly, while the water depth, which determined the wetted surface area of paddles, increased both linearly. Increasing the rotational speed decreased relative pumping efficiency relative to power used. Under the given field operational conditions, the predicted power requirement appropriately corresponded with the measured power requirement and the predicted values were within 95% of measured values. Good agreement was also noted between measured and predicted water flow rates, and the predicted values were 91.4% of the measured values.Based on the models developed, it was projected that increasing the wetted surface area of paddles is more energy efficient than increasing the rotational speed and minimizes mechanical failure due to high torque. However, the power requirement was also projected to increase with increasing wetted surface area at a certain threshold, as attempts to decrease the rotational speed were made to achieve a target water flow rate.

A pore network model for simulating non-ideal gas flow in micro- and nano-porous materials

The capability to simulate real gas flow in porous materials with micro- and nano-meter-scale pores is of importance in many applications, such as gas extraction from shale reservoirs, and the design of gas-based fuel cells. A node-bond pore-network flow model (PNFM) has been developed for gas flow where it is the only fluid phase. The flow conductance equation includes the usual Darcy flow terms, and additional terms that capture the contributions from slip flow to Knudsen diffusion. With respect to the case for a non-ideal gas, the extra contributions, which are necessary, to the coefficients of the Darcy and Knudsen terms, are expressed in terms of reduced temperature and pressure, using van der Waals’s two-parameter principle of corresponding states. Analysis on cylindrical pores shows that the coefficient deviates from that of the non-ideal gas case by more than 80% in the Darcy term, while between −80% and 150% in the Knudsen term, when the physical states approach to the critical state of the fluid. Although the deviations become smaller when the states are away from the critical state, they remain relatively large even at conditions relevant to practical applications. The model was applied to a pore network of a realistic 3D shale model to show slippage and Knudsen effects on the predicted permeability and the sensitivity to pore sizes. Simulations were carried out for methane under the operational conditions of typical shale-gas reservoirs, and nitrogen under the conditions of laboratory experiments. The results show that the ratio of gas and Darcy permeability correlates positively and strongly with the pore size but inversely with the gas pressure and Tangential Momentum Accommodation Coefficient (TMAC) in the slip term, which can impact gas permeability disproportionally. The results are in favour of controlling the rate of gas depressurisation to avoid early depletion in shale gas production. The methane permeability is shown to be 30% greater, relatively, than that when the ideal gas law is applied, even under normal field operational conditions, while the nitrogen permeability can only approximate the methane permeability within a certain range of field operational conditions when the slip flow is not dominating.

Water-based condensation particle counters comparison near a major freeway with significant heavy-duty diesel traffic

This study compares the instrumental performance of three TSI water-based condensation particle counter (WCPC) models measuring particle number concentrations in close proximity (15 m) to a major freeway that has a significant level of heavy-duty diesel traffic. The study focuses on examining instrument biases and performance differences by different WCPC models under realistic field operational conditions. Three TSI models (3781, 3783, and 3785) were operated for one month in triplicate (nine units in total) in parallel with two sets of Scanning Mobility Particle Sizer (SMPS) spectrometers for the concurrent measurement of particle size distributions. Inter-model bias under different wind directions were first evaluated using 1-min raw data. Although all three WCPC models agreed well in upwind conditions (lower particle number concentrations, in the range of 103–104 particles cm−3), the three models' responses were significantly different under downwind conditions (higher particle number concentrations, above 104 particles cm−3). In an effort to increase inter-model linear correlations, we evaluated the results of using longer averaging time intervals. An averaging time of at least 15 min was found to achieve R2 values of 0.96 or higher when comparing all three models. Similar results were observed for intra-model comparisons for each of the three models. This strong linear relationship helped identify instrument bias related to particle number concentrations and particle size distributions. The TSI 3783 produced the highest particle counts, followed by TSI 3785, which reported 11% lower during downwind conditions than TSI 3783. TSI 3781 recorded particle number concentrations that were 24% lower than those observed by TSI 3783 during downwind condition. We found that TSI 3781 underestimated particles with a count median diameter less than 45 nm. Although the particle size dependency of instrument performance was found the most significant in TSI 3781, both models 3783 and 3785 showed somewhat size dependency. In addition, within each tested WCPC model, one unit was found to count significantly different and be more sensitive to particle size than the other two. Finally, exponential regression analysis was used to numerically quantify instrumental inter-model bias. Correction equations are proposed to adjust the TSI 3781 and 3785 data to the most recent model TSI 3783.

Underway determination of dissolved inorganic carbon in estuarine waters by gas-diffusion flow analysis with C4D detection

The development and evaluation of a gas diffusion flow analysis system for the underway determination of dissolved inorganic carbon in marine and estuarine waters is described. Carbon dioxide produced when sample is injected into an acidic donor stream, diffuses through an efficient hollow fibre microporous membrane into an acceptor stream of ultrapure water, where the resultant changes in electrical conductivity are detected using a contactless capacitively coupled conductivity detector (C4D). The optimal parameters for the construction and operation of the C4D system are reported. Under field operational conditions, the flow analysis method had a linear calibration range for DIC of 0.2–10 mM, a limit of detection of 0.12 mM, repeatability of 0.46% RSD (n = 9 at 6 mM), a sample throughput of 90 h−1 and excellent correlation with comparative analyses (R2 = 0.9951, n = 16). The system was used to perform >250 determinations of DIC measurements underway during a short cruise on the Yarra River estuary, which demonstrated that DIC was conservative over much of the salinity gradient, with the exception of the low salinity region which exhibited the effects of respiratory CO2 and other DIC inputs. The results illustrate the advantages of the use of rapid flow analysis techniques for chemical mapping in transient environments like estuaries.

Wear behavior of carbonitride-treated ploughshares produced from 30MnB5 steel for soil tillage applications

The effects of gaseous carbonitriding processes on wear characteristics of 30MnB5 steel were investigated. The matrix of the carbonitride treated samples has a better wear resistance compared to the substrates of the conventionally heat-treated sample in laboratory conditions. The carbonitriding treatment condition giving rise to the lowest wear weight loss with the pin-on-disc wear machine was selected in order to harden ploughshare specimens to be tested in field experiments. The carbonitriding process at 860°C, with 0.9% C, and 0.6 m3/h NH3 for 105 min and quenched in 60°C oil followed by a 60 min tempering process at 140°C decreased 14.65% of total wear weight loss and 26.47% of total wear dimension loss of the ploughshare specimens in comparison to the conventional heat treatment process in field operational conditions.

Low-cost geochemical surveys for environmental studies in developing countries: Testing a field portable XRF instrument under quasi-realistic conditions

Environmental monitoring, as a prerequisite for environmental risk assessment, is crucial in developing nations from Africa, Latin America, South East Asia, or Melanesia, where conspicuously most of the World's mining activity concentrates. One of the most important environmental problems relates to the disposal of mine concentrates to river systems (e.g., Irian Jaya or Papua New Guinea). However, environmental monitoring is severely restricted in developing countries due to the chronic lack of funds. This paper explores the potential for a wider use of Field Portable X-Ray Fluorescence Spectroscopy instruments (FPXRFs) in fast, real-time, cost-effective environmental surveys for heavy metal dispersal in developing countries, where access to fully equipped geochemical labs is not usually a viable option. We simulated a scenario resembling conditions to be found in a remote region affected by mining-derived metal pollution where no proper laboratory facilities existed. We used an OXFORD X-MET 3000TX XRF analyzer under quasi-realistic conditions, relying solely on the instrument to allow geochemical characterization of a highly polluted Pb–Zn old mining district in the Alcudian Valley of central Spain. Our results for Pb, Zn, Cu, As, and Cd from 12 mine sites showed an excellent performance of the instrument, both under real-time and laboratory conditions. Furthermore, the instrument proved to be fit to endure a variety of field operational conditions and was able to deal with different types of samples, including tailings, soils, and stream sediments. Thus, taking into account the affordability of FPXRFs in relation to bench-top laboratory metal analyzers and their operational simplicity, we suggest that these portable instruments should become ‘the equipment of choice’ for environmental monitoring in developing countries. In this respect, FPXRFs satisfy the system-independence criterion for sustainable development, i.e., the instrument can stand alone and do its job with few or no other supporting facilities or devices. We go further on these matters providing some hints on how FPXRFs could become widely available via international cooperation, and the technical and social benefits that such equipments could bring to foreign aid recipient countries.

Investigation of the reduction of mouldboard ploughshare wear through hot stamping and hardfacing processes

The effects of the hot stamping process and different hardfacing techniques, such as shielded metal arc welding (SMAW) and gas metal arc welding (GMAW), on the abrasive wear of ploughshares were investigated under field operational conditions. The abrasive wear losses were determined by measuring the weight and dimension changes before and after tillage. The wear losses of hot-stamped and hardfaced ploughshares were less significant than those of the conventionally heat-treated ploughshare specimens used under field conditions. Conventional heat treatment and hardfacing by the SMAW process decreased the wear weight losses by 46.31% and the dimensional losses by 86.77% in comparison to the performance of the conventionally heat-treated ploughshares. These values were 36.90% and 88.17%, respectively, for conventional heat treatment and hardfacing by the GMAW process. There were no statistically significant differences between the SMAW and GMAW hardfacing processes in terms of wear losses. Hot stamping and heat treatment applications on the ploughshare also decreased wear losses by 19.03% and dimension losses by 13.82% in comparison to the conventional heat treatment process. According to the results of the overall study, hot stamping and hardfacing by SMAW and GMAW processes can be recommended as efficient solutions for decreasing the wear losses of ploughshares.

Development and validation of a real-time quantitative PCR assay for rapid identification of Bacillus anthracis in environmental samples

A real-time polymerase chain reaction (PCR) assay was developed for rapid identification of Bacillus anthracis in environmental samples. These samples often harbor Bacillus cereus bacteria closely related to B. anthracis, which may hinder its specific identification by resulting in false positive signals. The assay consists of two duplex real-time PCR: the first PCR allows amplification of a sequence specific of the B. cereus group (B. anthracis, B. cereus, Bacillus thuringiensis, Bacillus weihenstephanensis, Bacillus pseudomycoides, and Bacillus mycoides) within the phosphoenolpyruvate/sugar phosphotransferase system I gene and a B. anthracis specific single nucleotide polymorphism within the adenylosuccinate synthetase gene. The second real-time PCR assay targets the lethal factor gene from virulence plasmid pXO1 and the capsule synthesis gene from virulence plasmid pXO2. Specificity of the assay is enhanced by the use of minor groove binding probes and/or locked nucleic acids probes. The assay was validated on 304 bacterial strains including 37 B. anthracis, 67 B. cereus group, 54 strains of non-cereus group Bacillus, and 146 Gram-positive and Gram-negative bacteria strains. The assay was performed on various environmental samples spiked with B. anthracis or B. cereus spores. The assay allowed an accurate identification of B. anthracis in environmental samples. This study provides a rapid and reliable method for improving rapid identification of B. anthracis in field operational conditions.

The Measurement of Man-Machine Systems under Field Operational Conditions

The requirements for and special problems involved in human factors field testing are described. With one exception field testing is simply an extension of laboratory testing to the operational-use environment. The exception is the inability to control and test individual variables. The purpose of field testing is to verify that the system performs according to specification. This can be accomplished by comparing field performance with the system description or “template”.