Laboratory Test Environment Research Articles

Improvements in ground-fault protection of unit-connected generator stator winding using laboratory test environment

This paper describes an idea of realization of a software–hardware laboratory environment enabling to run research and implementation in the area of ground-fault protection of modern unit-connected generators. There are three basic elements in this environment: simulation model of a unit-connected generator for investigating intermittent arc ground-faults in generator stator winding, PC-based system for ground-fault waveforms synthesis and microprocessor-based hardware for implementation of a new protection algorithm developed by authors.

Which are the right test conditions for the simulation of high temperature alkali corrosion in biomass combustion?

AbstractThe use of renewable energy sources for the generation of electricity has gained much interest in recent years. Biomass has the potential of being a CO2 neutral energy source that could provide a significant proportion of the ever‐increasing energy demand. The easiest and most straightforward utilization of the energy content of biomass is direct combustion. The thermal energy of the biomass released in the combustion process is utilized by heating water or steam to produce electricity or heat or both (CHP). Whereas the heat production requires only modest temperatures in the water or steam circuit, producing electricity with high efficiency is not possible without high steam parameters (temperature and pressure). The heat market being quite saturated, the economic potential is in the electricity market. High heat transfer surface temperatures coupled with biomass fired steam generators have resulted, however, in serious corrosion of the heat transfer surfaces, especially in the hottest section of the convection superheaters. The type of corrosion found in biomass boilers is not encountered in fossil fuel fired boilers and the mechanism causing it is not fully understood. The development of new alloys that could withstand these harsh environments would benefit tremendously if the test conditions in the laboratory tests could be chosen so that they adequately resemble the corrosion environment in real boilers. Currently the high corrosion rate is believed to be caused by gaseous KCl that condense on the heat transfer surfaces. While KCl is certainly found in the corroded superheater tubes and probably has an important role in the corrosion reactions with the alloy, the formation of KCl on the cooled surface can also be heterogeneous. In this paper a discussion on the effect of alkali hydroxides, especially KOH, is presented. Biomass fuels have normally a high content of alkali metals and a low content of sulfur and chloride. The excess alkali will produce alkali hydroxides in the combustion environment. Alkali hydroxides then react with CO2 in the flue gases to form carbonates as the flue gases are cooled. The reaction with CO2, is however, very temperature dependent. The equilibrium being completely on the K2CO3 side with a gas temperature below 700 °C and completely on KOH side with a gas temperature above 900 °C. The hottest superheaters are normally located in the area where the flue gas temperature is 850°C–1000 °C. This makes KOH condensation on the tubes possible and subsequent heterogeneous reactions with HCl, SO2 and CO2 in molten phase forming KCl, K2SO2 or K2CO3. Although KOH is not thermodynamically stable at typical tube surface temperatures, a continuous flux condensing from the flue gases results in a corrosion environment on the tube where its activity has to be taken into account. Therefore it is suggested that KOH, either in gaseous or molten phase should be included in the laboratory test environments used for the testing of alloys for biomass combustion applications.

Hypersonic Experimental Facility for Magnetoaerodynamic Interactions

A hypersonic, weakly ionized gas experimental facility has been exclusively designed for basic research in magnetoaerodynamic& The weakly ionized air is generated by a combination of direct-current discharge, radio frequency radiation, or a combination of both in a blowdown, open-jet, Mach 5 channel. A collection of plasma diagnostic tools including optical spectroscopy, microwave devices, and Langmuir probes have also been successfully developed. The plasma field is determined to have an electron temperature around 10,000 K and the electron number density up to 2 × 10 1 2 /cm 3 . The magnetic field can be provided by a steady-state solenoid that can generate a maximum magnetic flux density up to 3 T or arrays of permanent magnets. Under this laboratory testing environment, the maximum Stuart number per unit length is around 1.5 per meter. As an example of the utility of the facility, a successful hypersonic magnetoaerodynamics experiment demonstrating the potential of a plasma actuator is described. In this experiment, the effect of an electromagnetic perturbation by a glow discharge near the leading edge is further amplified by viscous-inviscid interaction, creating a significant pressure rise over the plate surface. The induced surface pressure exhibits potential as a virtual flap for flow control.

Fluoxetine treatment decreases territorial aggression in a coral reef fish

Serotonin is an important neurotransmitter in the regulation of social interactions in many animals. Correlative studies in numerous vertebrate species, including fishes, indicate that aggressive males have lower relative serotonergic activity than less aggressive males. We used fluoxetine, a selective serotonin reuptake inhibitor, to experimentally enhance serotonergic neurotransmission in a territorial coral reef fish and test the role of this neurotransmitter in mediating aggressive behavior and dominance interactions. The bluehead wrasse, Thalassoma bifasciatum, has a complex social system in which large males aggressively defend spawning territories from intruders. In separate experiments, we tested the effects of chronic and acute fluoxetine treatments on aggressive behavior using a resident–intruder design. In a laboratory experiment, males treated daily with intraperitoneal fluoxetine injections for 2 weeks (6 μg/g bw) displayed fewer intruder chases than saline-treated controls. Chronically fluoxetine-treated males also showed lower levels of activity than saline controls prior to intruder trials. However, activity was not correlated with chases on an individual level, indicating the lower aggression displayed by fluoxetine-treated males was not due solely to general reductions in behavioral display. A field study exposed males to a confined territorial intruder following single intraperitoneal injections of fluoxetine (10 μg/g bw) or saline given to the same individual on different days. The frequency of aggressive chases following acute fluoxetine treatment was significantly lower than that following saline injections. This study experimentally supports the link between serotonin and aggressive behavior in fishes in both a controlled laboratory testing environment and the animal's natural habitat.

Measurements of air temperatures close to a low-velocity diffuser in displacement ventilation using an infrared camera

The near zone of supply air diffusers is very critical for the indoor climate. Complaints of draft are often associated with low-velocity diffusers in displacement ventilation because the air is discharged directly into the occupied zone. Today, the knowledge of the near zone of these air supply diffusers is insufficient, causing an increased need for better measuring methods and representation of the occupied zone. A whole-field measuring technique has been developed by the authors for visualization of air temperatures and airflow patterns over a large cross-section. In this particular whole-field method, air temperatures are measured with an infrared camera and a measuring screen placed in the airflow. The technique is applicable to most laboratory and field test environments. It offers several advantages over traditional techniques; for example, it can record real-time images within large areas and capture transient events. The purpose of this study was to conduct a parameter and error analysis of the proposed whole-field measuring method applied to a flow from a low-velocity diffuser in displacement ventilation. A model of the energy balance, for a solid measuring screen, was used for analyzing the influence of different parameters on the accuracy of the method. The analysis was performed with respect to the convective heat transfer coefficient, emissivity, screen temperature and surrounding surface temperatures. Theoretically, the temperature difference between the screen and the ambient air was found to be 0.2–2.4 °C for the specific delimitation in the investigation. However, after applying correction the maximum uncertainty of the predicted air temperature was found to vary between 0.62 and 0.98 °C, due to uncertainties in estimating parameters used in the correction. The maximum uncertainty can be reduced to a great extent by estimating the convective heat transfer coefficient more accurately and using a screen with rather low emissivity.

Test Results of Resonant Integrated Microbeam Sensor (RIMS) for Acoustic Emission Monitoring

The feasibility of detecting stress-wave acoustic phenomena with Honeywell's resonant microbeam-based MEMS sensor technology is presented. The baseline technical approach described here incorporates an integrated silicon microstructure and a resonant microbeam with micron-level feature size, and features frequency sensitivity up to 500 kHz. The stress-wave acoustic MEMS concept has been demonstrated successfully in the laboratory test environment to sense simulated acoustic emission (AE) events for structural fatigue crack monitoring applications. The technical design approach and laboratory test results are presented.

A finite element poro-inelastic analysis of borehole problems

A fully coupled finite element analysis for fluid saturated porous media has been developed. The analysis incorporates transient fluid flow in deformable porous media, based on Biot's theory. Fluid flow is governed by Darcy's law. The nonlinear constitutive relations for the solid frame, in terms of effective stresses, are constructed in accordance with generalized Columb criteria, with supplementary definitions of the deviatoric and hydrostatic damage indicators. Four parameters, based on characteristic experimental data, are designated independently to account for softening, confining pressure, dilation, and compaction effects. The stress-dependent permeability tensor is simplified to be diagonal, dependent on both deviatoric and hydrostatic damage indicators, as is the case for many granular rock materials. The performance of the method was assessed using selected examples. An example of the loading path effect on laboratory testing of borehole instability is presented. Two typical loading paths load-and-drill and drill-and-load, are studied in detail. The load-and-drill path resembles field situations, in which boreholes are drilled under in-situ stress conditions, while the drill-and-load path is more likely to be the case in a laboratory testing environment. While inelastic deformation is taken into account for both cases, the borehole is more stable than the predicted by elastic analysis, and it is found that the borehole is substantially more stable if it is drilled before being loaded. These differences are quantified using the numerical code.

Development of combustion catalysts for monolith reactors: a consideration of transport limitations

In the search for catalysts to be utilized in a new generation of catalytic gas turbine combustors it is not unusual to hear of catalysts that appear to have worked well in a laboratory environment but do not do so when installed in a high pressure pilot-scale rig. The influence that interphase and intraphase transport limitations may have on the rate of catalytic combustion of methane in a monolith reactor (with a 1.1 mm cell size) is investigated at a Reynolds number, Re = 10 3 (with) P = 2bar) and at Re = 10 4 (with P = 15bar), for bulk gas temperatures varying from 623–873 K and at a bulk methane mole fraction of 0.02. It is shown that it is not an easy task to evaluate chemical kinetic expressions at conditions which truly represent even the first stage (e.g., at gas temperatures from 623–973 K) in a catalytic gas turbine combustor, for as reaction rates become very fast, interphase and intraphase transport limitations also become significant, e.g., when comparing reaction rates evaluated at incorrectly assigned conditions, then even at a relatively low bulk fluid temperature= 773K, errors may vary from ca. 35% to 80% for Re = 10 4and10 3, respectively. In a laboratory test environment, where experiments may be performed close to atmospheric conditions, it is also shown that it is easy to over-temperature and hence damage the catalyst, and draw false conclusions about the catalyst being too active, e.g., considering interphase resistances alone, at a bulk fluid temperature of 773 K and Re = 10 3 the catalyst is damaged, whereas at Re = 10 4 this would not have occurred. As catalyst surface temperature exceeds 800 K, intraphase diffusion may become significant and the effectiveness factor soon becomes very much less than one. Therefore, reactor scale-up should be based on calculations where the combined effects of interphase and intraphase transport processes are coupled with reactions; scale-up based on simple multipliers, e.g., those derived from residence time or gas hourly space velocity, are unlikely to work. Modelling is shown to have an important role in catalyst and system design; if applied correctly, system development costs may be reduced.

Sensitivity of Occupant Response Subject to Prescribed Corridors for Impact Testing

A technology to study the sensitivity of impact responses to prescribed test conditions is presented. Motor vehicle impacts are used to illustrate the principles of this sensitivity technology. Impact conditions are regulated by specifying either a corridor for the acceleration time history or other test parameters such as velocity change, static crush distance, and pulse duration. By combining a time domain constrained optimization method and a multirigid body dynamics simulator, the upper and lower bounds of occupant responses subject to the regulated corridors were obtained. It was found that these prescribed corridors may be either so wide as to allow extreme variations in occupant response or so narrow that they are physically unrealizable in the laboratory test environment. A new corridor based on specifications for the test parameters of acceleration, velocity. crush distance, and duration for frontal vehicle impacts is given.

From field vibration data to laboratory simulation

The objective of a test program is to simulate a specified dynamic environment. The question is: How do I go from field-test data to a reasonable laboratory or finite-element simulation? This paper looks at a simple situation of a two degree-of-freedom vehicle that has a broadband excitation source and a two degree-of-freedom test item that can be attached to the vehicle. The paper shows that significantly different field data are obtained depending on field-test conditions, and vastly different simulation results are obtained when using these different field data as laboratory inputs. A relatively simple theoretical model is developed that explains how field data in this case can be modified in the frequency domain to obtain a more realistic laboratory test environment. This presentation shows that a general theory of vibration testing is needed, a theory that provides guidelines for this process of obtaining field data and developing realistic test specifications.

Mechanism of injury from air bag deployment loads

Loadings induced by deploying currently representative air bags were studied with driver surrogates (anesthetized swine) leaning against the system during inflation. Torso injury mechanisms were studied in a physiologic model, supported against a static steering wheel-mounted air bag system. Severe and extensive chest and abdominal injuries to the swine were observed in the tests. Loading caused by air bag deployment can occur in either of two phases. The first phase represents the initial punch out of the bag from the module; the second phase represents the membrane force of the inflating bag. Statistical analysis indicated that punch out induced injury because of the high rate of loading to the surrogate body region in direct contact with the air bag module. Membrane forces induced injury by high compression over a larger area. Punch-out loading might be reduced by allowing the bag to escape from other parts of the container not in contact with the driver during deployment. Loading by the inflating bag might be reduced by using a compliant steering system to support the module. The amount and rate of generated gas had only marginal effect on the cumulative injury. Even an inflator with inadequate gas output to protect a properly seated occupant had sufficient energy to induce severe injuries in a surrogate in contact with the inflating module. Analysis of the field relevance of the results must consider not only the injury potential given that a driver is in direct contact with the air bag module at the time of deployment, but also the expected field frequency of such an event. Analysis of the field relevance of the results must also consider the correlation of the laboratory test environment with real-world exposure.

Further discussion on processing technology

BDAQ53 is a readout system and verification framework for hybrid pixel detector readout chips of the RD53 family. These chips are designed for the upgrade of the inner tracking detectors of the ATLAS and CMS experiments. BDAQ53 is used in applications where versatility and rapid customization are required, such as in laboratory testing environments, test beam campaigns, and permanent setups for quality control measurements. It consists of custom and commercial hardware, a Python-based software framework, and FPGA firmware. BDAQ53 is developed as open source software with both software and firmware being hosted in a public repository.

Application of Ground/Air Data Link to General Aviation Operations

The Federal Aviation Administration (FAA) is currently upgrading secondary surveillance radars with systems which will have an integral data link capability, the Mode Select (Mode S) beacon system. These new systems will allow two-way data communications between ground systems (e.g., weather databases and Air Traffic Control (ATC) systems) and aircraft that are equipped with data link compatible Mode S transponders and suitable display and input devices. Initial data link services include both weather information and ATC advisories. The MITRE Corporation* is developing an in-house capability to perform end-to-end operational evaluation of data link services. Initially, a low-cost, portable pilot position man-machine interface is being developed for use in general aviation operations. The objective is to explore operational issues in laboratory and limited flight test environments, and to demonstrate these services on a data link I/O device, a laptop portable personal computer (PC) with touch panel. A group of pilots will bench test the interface design, and the results will be incorporated into the design used in flight testing. This paper describes the project's objectives and results to date, including implementation details and pilot test results.

Earthquake simulation and test procedure for communications equipment

A rational procedure for determining a regional earthquake test environment for communications facilities is described. The approach includes examination of a wide range of telephone building responses to arrive at an upper-bound response spectra. An acceleration time history test environment in the form of a synthesized earthquake is generated to match the spectra. The regional test is then established by linearly scaling the time history to the peak acceleration shown on a national earthquake design regionalization map. Further scaling to account for motion amplification for in-building location of equipment was achieved through examination of data gathered from the 1972 San Fernando earthquake. Communications equipment mounted on steel framework are tested for their earthquake vulnerability according to the specified laboratory test environment.