Ordinary Operating Conditions Research Articles

Design of a Wireless Sensor Node for Overhead High Voltage Transmission Power Lines

High Voltage (HV) overhead power lines are systems of interconnected elements that deliver massive amounts of electrical energy over long distances. Electrical conductors, used as energy carriers, are designed according voltage, current, and temperature rated value. Monitoring the power line's state variables is emerging as a crucial topic aiming at both determining the optimal real-time capability and defining a suitable model for Health Index assessment. A Wireless Sensor Network (WSN), consisting of many distributed sensor nodes that communicate with each other, can be a suitable tool to improve line ampacity by maintaining the operating variables in respect of their rated values. This paper investigates the design of an Energy Management System (EMS) for a wireless sensor for HV power line application and proposes a maximum power point tracker (MPPT). The behavior of the MPPT is discussed in terms of electromagnetic field laws and properties of magnetic materials. Ordinary and extraordinary operating conditions are investigated. The theoretical results are validated through a series of experimental tests. A prototype has been realized and tested for real operating currents. The tests are also used to verify the sensor's resilience in the presence of harsh fault conditions.

DC-port voltage balance strategy for three-phase cascaded H-bridge rectifier based on logic combination modulation

PurposeThe purpose of this paper is to propose a DC-port voltage balance strategy realizing it by logic combination modulation (LCM). This voltage balance strategy is brief and high efficient, which can be used in many power electronic devices adopting the cascaded H-bridge rectifier (CHBR) such as power electronic transformer (PET).Design/methodology/approachThe CHBR is typically as a core component in the power electronic devices to implement the voltage or current conversion. The modulation method presented here is aiming to solve the voltage imbalance problem occurred in the CHBR with more stable work station and higher reliability in ordinary operating conditions. In particular, by changing the switch states smoothly and quickly, the DC-port voltage can be controlled as the ideal value even one of the modules in CHBR is facing the load-removed problem.FindingsBy using the voltage balance strategy of LCM, the problem of voltage imbalance occurring in three-phase cascaded rectifiers has been solved properly. With the lower modulation depth, the efficiency of the strategy is shown to be better and stronger. The strategy can work reliably and quickly no matter facing the problem as load-removed change or the ordinary operating conditions.Research limitations/implicationsThe limitation of the proposed DC-port voltage balance strategy is calculated and proved, in a three-module CHBR, the LCM could balance the DC-port voltage while one module facing the load-removed situation under 0.83 modulation depth.Originality/valueThis paper provides a useful and particular voltage balance strategy which can be used in the topology of three-phase cascaded rectifier. The value of the strategy is that a brief and reliable voltage balance method in the power electronic devices can be achieved. What is more, facing the problem, such as load-removed, in outport, the strategy can response quickly with no switch jump and switch frequency rising.

Failure analysis of the segment finger bar mower and force interaction of the blade segment with the plant stem

Scientific observations on the quality and reliability of combine harvesters have shown that of all the delays of equipment, 32...35% of the total operating time, technical failures account for 17.4...19.8%. Most of the failures were observed with the failure of combine parts, mechanical transmissions, hydraulic systems, etc. Quantitative analysis of harvester failures has shown that most failures occur in the operation of the cutting device, namely the finger bar mower. The working hypothesis is that it is possible to increase the reliability of the cutting device of harvesting machines in ordinary operating conditions and in the event of sudden failures by applying a coating on the blade segment, without significantly changing its geometric parameters, and performing notches that ensure both a decrease in the mass of the segment and its destruction without plastic deformation when foreign objects enter the cutting zone. The main problem of the reliability of segments of cutting device, harvesting equipment, is the cutting edge of the blade, which wears out and deforms during operation. From the above, it follows that the purpose of the study is to improve the reliability of segment finger bar mower machines by improving the mechanical properties of segments, these investigations are relevant and of practical interest. The study includes the use of mathematical probability and reliability theory, analysis, and a systematic approach to provide an analytical description of the operation of a cutting device segment. The consequence of this scientific investigation is an analysis of failures and malfunctions of the machinery, presented graphically, a diagram of how a plant stem segment is cut and the forces acting on the stem and the segment during the cutting process are depicted. These materials have scientific and informative content that would be of interest to engineers and scientists in the process of research and production of cutting device segments

Novel strategy for rapid start-up and stable operation of anammox: Negative pressure coupled with the direct-current electric field

An application challenge of anaerobic ammonia oxidation (anammox) is the slow proliferation rate of anaerobic ammonium oxidation bacteria (AnAOB). This study adopted negative pressure coupled with the direct-current electric field (NP–DCEF) to evaluate system nitrogen removal performance. Results showed that the total nitrogen removal rate (TNRR) of the NP–DCEF system was stable at 88.6% after seven days. Compared with that of the ordinary operating system (45.4%), the relative abundance of Candidatus–kuenenia considerably increased from 51.9% to 57.6%. Under transient and long-term influent fluctuation, the NP–DCEF system showed high nitrogen removal performance. The specific activity of AnAOB (SAA) reached 11.0 mg N∙g Vss−1 h−1 under load fluctuation, and it was 8.7 mg N∙g Vss−1 h−1 under ordinary operational conditions. In addition, the specific activities of hydrazine dehydrogenase (HDH) and hydrazine synthetase (HZS) reached 32.66 and 92.95 U∙L−1, which are considerably higher than those under the ordinary operating conditions (18.41 and 63.20 U∙L−1). These results indicated that the novel operation strategy has specific feasibility and potential for the start-up and long-term operation of anammox.

Development of a methodology for calculating the integral toxicity of exhaust gases of a diesel engine running on alternative fuels

Currently, most methods for assessing the content of harmful substances in the exhaust gases (EG) of diesel internal combustion engines (DICE) differ in research programs that simulate the most significant operating modes of a tractor or motor vehicle DICE in ordinary operating conditions. And to assess their toxicity, such different methods are used as a study under steady-state operating modes that ensure the constancy of the performance of a DICE, and its study under changing parameters in transient modes. DICE of tractors, self-propelled agricultural machines and other off-road equipment are tested at a stand equipped with a loading device and measuring instruments for monitoring tests and collecting data necessary for processing test results. Emissions are determined during the sequential operation of the DICE at steady-state modes. Each mode has its own weighting coefficient, which characterizes the contribution of this mode to environmental pollution during the operation of a DICE.

The rational repair and maintenance cycle of the KamAZ car gearbox taking into account the pre-repair operating time

A significant proportion of the costs and downtime for repairs are on transmission units, and especially on the gearbox (GB). Based on the research results presented in the work, up to 76% of all transmission failures fall on the gearbox of a KamAZ 6540 automobile under ordinary operating conditions. The purpose of the study is to justify the repair and maintenance cycle (RMC) of the gearbox of the KamAZ 6540 automobile, taking into account the pre-repair operating time. The proposed methodology for assessing the pre-repair resource allows you to select the resource elements of the gearbox, taking into account the value of their resource and coefficient of variation. The structure of the RMC proposed in the work provides for: the first current repair during running hours - 125940 km; first overhaul during running hours - 251880 km; second current repair during running hours - 377820 km; second overhaul during running hours - 503760 km. Thus, changing the structure of the gearbox REC allows increasing the gearbox resource from 380 to 500 thousand km.

Experimental analysis of the water consumption effect on the dynamic behaviour of a real pipe network

ABSTRACT This paper presents the results of the monitoring and analysis of the dynamic behaviour of the Gorino Ferrarese (Ferrara, Italy) water distribution system. The network is subjected to ordinary operational conditions, (i.e. no manoeuvres on pumps or valves are considered), the aim being to show that user demand may generate frequent and not negligible pressure variations. Pressure and discharge were monitored for two days in different sections of the network. The dynamic behaviour of the system is then characterized by analysing the pressure changes at the measurement sections in the time and frequency domains. Such analyses highlight that pressure signals are characterized by long-term changes (low-frequency) on which shorter period (high-frequency) ones overlap. Long-term oscillations show a similar trend at all measurement sections and are characterized by certain dominant frequencies, linked to the topological and mechanical characteristics of the network. Instead, high-frequency pressure fluctuations related to user activity vary in amplitude both spatially and temporally.

Boosting silicon photovoltaic efficiency from regasification of liquefied natural gas

The regasification of liquefied natural gas from 111 K to ambient temperature represents a standard large-scale process that currently dissipates a worldwide total of ∼105 TWh/yr of cold energy to seawater. We consider the potential efficiency enhancement attainable by exploiting this nominally free cold energy to cool conventional silicon photovoltaics. Whether the temperature dependence of photovoltaic performance at ordinary operating conditions can be extrapolated to cryogenic temperatures has remained unexplored territory. In measuring the principal PV performance variables down to cryogenic temperatures, we show that such cooling can boost PV efficiency by close to 80% relative.

Thermal and Energy-Efficiency Assessment of Hybrid CLT–glass Façade Elements

Façade elements are a building component that satisfies multiple performance parameters. Among other things, “advanced façades” take advantage of hybrid solutions, such as assembling laminated materials. In addition to the enhanced mechanical properties that are typical of optimally composed hybrid structural components, these systems are energy-efficient, durable, and offer lighting comfort and optimal thermal performance, an example of which is the structural solution developed in collaboration with the University of Zagreb and the University of Ljubljana within the Croatian Science Foundation VETROLIGNUM project. The design concept involves the mechanical interaction of timber and glass load-bearing members without sealing or bonding the glass-to-timber surfaces. Following earlier research efforts devoted to the structural analysis and optimization of thus-assembled hybrid Cross-Laminated Timber (CLT)-glass façade elements, in this paper, special focus is given to a thermal and energy performance investigation under ordinary operational conditions. A simplified numerical model representative of a full-size building is first presented by taking advantage of continuous ambient records from a Live-Lab mock-up facility in Zagreb. Afterwards, a more detailed Finite Element (FE) numerical analysis is carried out at the component level to further explore the potential of CLT–glass façade elements. The collected numerical results show that CLT–glass composite panels can offer stable and promising thermal performance for façades similar to national and European standard requirements.

Laboratory Analysis of a Piston-Actuated Pressure-Reducing Valve under Low Flow Conditions

The effectiveness of pressure-reducing valves (PRVs) for optimal pressure management of water distribution networks (WDNs) is proven, but problems and operational limitations have been highlighted by some recent experiences. In this study, we analyse the functioning of a piston-actuated pressure-reducing valve (PA-PRV) with a mechanical pilot which is subjected to low-flow regimes, a condition that is often observed in real water distribution networks. The analyses were carried out by means of laboratory tests featuring two sets of experiments, i.e., (a) by testing the behaviour of the PRV when a pre-established initial value and subsequent variation of flow rate occurs in the system and (b) by testing the PRV against a temporal series of flow rates observed at the inlet section of a real district metered area. The first set of tests showed that the PA-PRV tends not to maintain pressure at the imposed set-point and exhibits an unstable behaviour characterised by significant pressure oscillations under some flow rate conditions. The second set of laboratory tests showed that the anomalous behaviour identified in the first set of tests can occur under ordinary operational conditions of a network.

Close-to-Application Test Methodology Validated by a Baseline Study for Novel Bearing Developments in Aircraft Turbines

The main objective of the present paper is the validation of new methods concerning experimental investigations of journal bearings under ordinary and extraordinary operational conditions. Derived results should facilitate the determination of damage mechanisms and a qualitative ranking for a prospective coating development. Prior investigated scenarios like start/stop and emergency running behavior were extended by starved and unlubricated experiments for an aircraft application. Focusing on thermal stability and reproducibility, two new subscale test strategies were developed derived from generalized operational conditions of journal bearings. For an improved ex-situ wear measurement of bearing shells, a new device was developed successfully. The results showed that the newly designed test methodologies are suitable to investigate unlubricated coatings leading to conclusive and repetitive results.

Basis of Guidelines for Structural Design and Thermal Assessment of Buildings with Hybrid CLT-Glass Elements

Facade elements are known to represent a building component with multiple performance parameters to satisfy. Among others, “advanced facades” take advantage from hybrid solutions, like the assemblage of laminated materials. In addition to enhanced mechanical properties that are typical of optimally composed hybrid structural components, these systems are energy efficient, durable and offer lightening comfort and optimal thermal performance. This is the case of the structural solution developed in joint research efforts of University of Zagreb and University of Ljubljana, within the Croatian VETROLIGNUM project. The design concept involves the mechanical interaction of timber and glass load-bearing members, without sealing or glued glass-to-timber surfaces. Laminated glass infilled timber frames are in fact recognized as a new generation of structural members with relevant load-carrying capacity (and especially the enhancement of earthquake resistance of framed systems), but also energy-efficient and cost-effective solutions. In this paper, brief guidelines for the optimal structural design of glass infilled Cross-Laminated Timber (CLT) framed systems are presented. A special focus is then dedicated to the thermal performance assessment of these innovative CLT-glass facade modules under ordinary operational conditions. Finite Element numerical models of single elements are developed to reproduce a full-size mock-up building. The actual thermal performance is thus carried out with the support of continuous ambient records. The numerical results show that the CLT-glass composite facade system can be efficient and offer stable performances, in line with national and European standards requirements.

Probability‐based seismic reliability assessment method for substation systems

SummaryPower systems play a key role in emergency rescue after an earthquake. Substations are among the most important components of a power system, so it is necessary to study their seismic reliability after an earthquake. Most studies, however, have focused on the seismic behavior of major electrical equipment or the reliability of the substation under ordinary operational conditions. The seismic reliability of substations as a system has not been thoroughly studied. This study proposes a new probability‐based method to evaluate the seismic reliability of complex engineering systems such as substations. The proposed method developed the state tree to construct a greatly simplified system model that enables the failure probability to be calculated for the whole system, with explicit consideration of correlations among various components. A typical 220/110/10‐kV substation was studied with this method, and the most critical components were identified.

Measurement error induced by the power-frequency delay of the light source in optical correlation-domain distributed Brillouin sensors.

Direct current modulation of a semiconductor laser is a key method adopted in most optical correlation-domain distributed Brillouin sensors such as Brillouin optical correlation-domain analysis (BOCDA) and reflectometry (BOCDR) for localizing the sensing position by synthesis of an optical coherence function. We report that distributed measurement of Brillouin frequency by the BOCDA or BOCDR system can suffer significant distortion caused by phase delay between output power and frequency variations of the modulated light source. We calculate characteristics of the distortion by numerical simulations, and compare the results with experimental data obtained by a BOCDA system for confirmation. Our results show that a maximum error of more than 30MHz can occur in Brillouin frequency measured under ordinary operating conditions with MHz-order direct current modulation.

Удосконалення морально-психологічного забезпечення як невід’ємна складова захисту військ (сил) та протидії негативному інформаційно-психологічному впливу

An information and psychological impact as a specific modern phenomenon and effective means of achieving the objectives at the tactical, operational and strategic levels is analyzed. A system to counteract the negative information impact on personnel and commanding staff of the Armed Forces of Ukraine in the extreme and ordinary operating conditions is examined.

Detection and reduction of tungsten contamination in ion implantation processes

AbstractIn this paper, we review the results of some studies addressing the problem of tungsten contamination in implantation processes. For some tests, the implanter was contaminated by implantation of wafers with an exposed tungsten layer, resulting in critical contamination conditions. First, DLTS (deep level transient spectroscopy) measurements were calibrated to measure tungsten contamination in ion‐implanted samples. DLTS measurements of tungsten‐implanted samples showed that the tungsten concentration increases linearly with the dose up to a rather low dose (5×1010 cm–2). Tungsten deactivation was observed when the dose was further increased. Under these conditions, ToF‐SIMS revealed tungsten at the wafer surface, showing that deactivation was due to surface segregation. DLTS calibration could therefore be obtained in the linear dose regime only. This calibration was used to evaluate the tungsten contamination in arsenic implantations. Ordinary operating conditions and critical contamination conditions of the equipment were compared. A moderate tungsten contamination was observed in samples implanted under ordinary operating conditions. This contamination was easily suppressed by a thin screen oxide. On the contrary, implantations in critical conditions of the equipment resulted in a relevant tungsten contamination, which could be reduced but not suppressed even by a relatively thick screen oxide (up to 150 Å). A decontamination process consisting of high dose implantations of dummy wafers was tested for its efficiency to remove tungsten and titanium contamination. This process was found to be much more effective for titanium than for tungsten. Finally, DLTS proved to be much more sensitive that TXRF (total reflection X‐ray fluorescence) in detecting tungsten contamination. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Smart maintenance of riverbanks using a standard data layer and Augmented Reality

Linear buffer strips (BS) along watercourses are commonly adopted to reduce run-off, accumulation of bank-top sediments and the leaking of pesticides into fresh-waters, which strongly increase water pollution. However, the monitoring of their conditions is a difficult task because they are scattered over wide rural areas. This work demonstrates the benefits of using a standard data layer and Augmented Reality (AR) in watershed control and outlines the guideline of a novel approach for the health-check of linear BS. We designed a mobile environmental monitoring system for smart maintenance of riverbanks by embedding the AR technology within a Geographical Information System (GIS). From the technological point of view, the system's architecture consists of a cloud-based service for data sharing, using a standard data layer, and of a mobile device provided with a GPS based AR engine for augmented data visualization. The proposed solution aims to ease the overall inspection process by reducing the time required to run a survey. Indeed, ordinary operational survey conditions are usually performed basing the fieldwork on just classical digitized maps. Our application proposes to enrich inspections by superimposing information on the device screen with the same point of view of the camera, providing an intuitive visualization of buffer strip location. This way, the inspection officer can quickly and dynamically access relevant information overlaying geographic features, comments and other contents in real time. The solution has been tested in fieldwork to prove at what extent this cutting-edge technology contributes to an effective monitoring over large territorial settings. The aim is to encourage officers, land managers and practitioners toward more effective monitoring and management practices.

Method for Calculating the Neutron Diffusion Coefficient in a Nuclear Reactor Cell

An approach to solving the three-dimensional transport equation is described. Directional probabilities, which make it possible to analyze axial leakage numerically, are defined. The problems of modeling the boundary conditions for the neutron flux under ordinary operating conditions of reactors and under the conditions of dewatering are discussed. The results obtained show that if the effect of the spectrum of the two-dimensional problem of a VVER cell is taken into account, then the axial leakage changes, especially near the reflector. The axial leakage also increases if the cell contains dewatered channels, but only if the boundary conditions are modeled in the form of mirror reflection on a real hexahedral boundary. This effect vanishes if the equivalent cylindrical cell approximation is used and the boundary conditions are modeled in the form of isotropic reflection.

Polymers' ultrafine particles for drug delivery systems precipitated by supercritical carbon dioxide + organic solvent mixtures

The applicability of supercritical antisolvent precipitation (SAS) is restricted to hydrophobic substances because of the very limited solubility of water in CO2 at ordinary SAS operating conditions (40–60°C, 10–25MPa). To overcome this limitation, a technique has been developed, named expanded liquid antisolvent (ELAS), in which mixtures of supercritical carbon dioxide (scCO2) and organic solvents, at expanded liquid conditions, are used as the antisolvent: water solubility is widely enhanced.In this work, sodium alginate and polyvinyl alcohol (PVA), two water-soluble polymers, used as carrier for drug delivery systems, were successfully micronized by ELAS. Different antisolvent mixtures were used: scCO2+ethanol, scCO2+acetone and scCO2+isopropyl alcohol. Operating at 15MPa and 40°C, varying the organic co-antisolvent, the co-antisolvent mole fraction and the concentration of the polymer in the aqueous solution, nanoparticles (with a mean diameter of about 200nm), microparticles with smooth surface (with a mean diameter in the range of 0.9–12.5μm for sodium alginate and 2–9μm for PVA) and nanostructured microparticles (with a mean diameter of about 11μm) were produced. XRD analyses on the processed powders revealed that no modifications in the polymer structure were induced by ELAS processing. Solvent residue analyses revealed that the co-antisolvent residue ranged between 50 and 300ppm depending on the organic solvent used.

Low-NOx Modification of a Heavy Fuel Oil Swirl Burner Based on Semi-Industrial Scale Experimental Tests

A proposed swirl burner was modified from a burner used in a 300 MWe oil-fueled power plant. In particular, burner construction, including expanded nozzles, swirl numbers, and air ratios were changed. Then, experimental tests were carried out in a semi-industrial test rig with a horizontal cylindrical furnace with a single-swirl burner. The thermal input of the furnace was 9 MW. The species concentrations of O2, CO, and NOx in the flue gas were measured. NOx emission with the original burner was 320 ppm (3 vol % O2). However, NOx emission decreased to 195 ppm (3 vol % O2) with the proposed burner during optimal operation. Through a series of adjusting experiments, a 35–39% abatement of the NOx emission from the single-burner test could be maintained when the original burner was replaced by the proposed one. NOx emission measured from a full-scale industrial furnace is approximately 341 ppm (3 vol % O2) under ordinary operating conditions. The predicted NOx concentration from the industrial furnace could achieve 207.8 ppm (3 vol % O2) employing the proposed swirl burner under optimal operating conditions. The flow fields (including the recirculation zone and turbulent intensity) downstream of the two burners were compared on the basis of the numerical results. A CCD image system was applied to capture the flame structure downstream of the burner. A mushroom-shaped flame structure was observed with the proposed burner, whereas a fan-shaped diffusion flame was observed with the original burner. A strengthened division in the flame was formed at the burner outlet with the proposed burner. Temperatures ranged from 1184 to 2114 °C downstream of the burner, which was determined through the two-color pyrometry method for each burner. The minimum temperature of the reference section was reduced by 154 °C, and the average temperature was reduced by 76.9 °C when the proposed burner was applied. The proportion of the temperature region higher than 1500 °C in the reference section was calculated. The initial proportion was 94.96%, which was reduced to 80.91% when the proposed burner was applied. This represents a decrease of 14.05% through the modification.