Actual Field Experience Research Articles

Field experience with a peak-demand tariff at the Andhi Khola hydel and rural electrification project

The Andhi Khola Hydel and Rural Electrification Project (AHREP) was formally commenced in a June 1982 agreement between the United Mission to Nepal and His Majesty's Government of Nepal. It was established as a pilot project for the “development of appropriate technology and suitable methods and tariffs for rural electrification.” By virtue of its being a pilot project many novel innovations were implemented at AHREP. The focus of this paper is confined to a consideration of tariff. Its specific purpose will be to document field experiences resulting from the implementation of a peak-demand tariff. The unique contribution of this paper to the annals of rural electrification is that while much data in the literature is available regarding the consumption patterns of metered consumers, to the best knowledge of the author this is the first paper ever published summarising comparative data of metered and peak-demand consumers. The basic conclusion of this treatise is that technically speaking, experience with a peak-demand tariff at AHREP has been positive. This paper specifically demonstrates the benefits of load-distribution-over-time achievable at the household level utilising current limiters and “two-tier” meters, and also the broader implications of such upon system load factors. Recognition of these benefits, of course, does not negate broader valid concerns including the potential theft of electricity, the reliability and accuracy of load monitoring devices, the uneconomical use of electricity, etc., to which a peak-demand tariff regime is indeed vulnerable. Despite these legitimate constraints, the author wishes to articulate the opinion via this paper that based upon actual and extensive field experience, the AHREP peak-demand tariff is worthy of documentation and consideration for potential duplication in a broader realm throughout Nepal – and with due sensitivity given to context, possibly abroad.

Commutation failures in HVDC transmission systems

This paper provides a formulation for the initiation or onset mechanism of commutation failures in line-commutated thyristor power converters, assuming infinite (zero impedance) AC systems. A theoretical development and a parametric analysis is given. Theory validation by simulation and comparison to actual field experience data is also given.

Teaching Plasticulture Technology to Undergraduate Students

T caching the course Plasticulture Technology, for the intensive production of vegetable crops, to researchers, extension professionals, industry personnel, and growers around the country has been very successful using short courses, seminars, and on-farm demonstrations (Lament, 1989; Lament et al. , 1992, 1993, 1994). It is important that undergraduate horticulture-agriculture students also are introduced to the latest plasticulture technology and that they can practice using this technology as part of their undergraduate education. The challenge was to provide meaningful outdo-or activities involving the latest technology in the field of plasticulture for 55 undergraduate students enrolled in the Vegetable Production class. The objective of developing this hands-on instructional tool was to reinforce the information presented in the classroom lectures with actual field experiences or activities in the laboratory portion of the class. A secondary consideration and challenge was to provide these activities close to the greenhouse, so that valuable lab time was not consumed traveling to a grower’s property or the Kansas State Univ. Horticulture Research Center-

The efficacy of interactive video for teaching basic classroom management skills to pre-service teachers

Results The results of this study are promising given the relatively brief treatment period. The significant, but not dramatic, achievement gains imply that more time spent with the simulation may result in higher achievement. The significant findings from the stages of concern instrument also suggest that the simulation may have begun to cause the expected shift in concerns. As discussed earlier, the C&I students' high concerns across most of the stages showed they (a) had some knowledge about classroom management, (b) had considered their limitations, (c) had wondered how they would learn more, and (d) had projected their needs to the time when they would enter the field. With such high concerns across the stages, the anticipated treatment effect from a longer treatment will probably be limited to a reduction of concerns in the earlier stages and only a slight increase in the later stages, which occurred to a limited degree with the C&I 7 group. As discussed earlier, a longer treatment may result in more dramatic changes. However, an important point worth emphasizing is that computers are rarely the sole learning medium. Computers are generally regarded as learning tools that have the potential to enrich traditional learning tasks and facilitate higher levels of achievement. Perhaps the classroom management simulation would prove more effective if used as an integral part of a class in which an instructor provided more concrete procedures for program use and goals as outcomes. Group discussions, in which various management principles would be analyzed for appropriateness and inappropriateness in given situations, would be an important part of such a structured approach. Utilizing the simulation in such a manner would eliminate user tendencies to (a) neglect the specifics of and differences between the principles of management and (b) hurry through the scenarios in order to just “see what happens” without attending to the principles demonstrated or infringed. Because CAI is an effective mode for independent study (Robinson, 1988), another possible use of the simulation is to make it available for students in the field who are forced to deal with management problems on an everyday basis in addition to their many other responsibilities. After exposure to real situations, users may be more receptive to exploring the scenarios more intensely to improve their automaticity in selecting appropriate management strategies based on knowledge gleaned from the simulation. Conclusion Interactive-video computer-based simulations are potentially useful for introducing pre-service teachers to classroom situations because they are dependable, consistent, and easily accessible (Hasselbring et al., 1987; Roblyer, 1988). Education staff often have difficulty finding and coordinating quality, initial field experiences for their students. If field experiences can be effectively simulated, work on initial experiences can be pursued at any time, making those experiences dependable and easily accessible. Easy accessibility, combined with time compression, will also result in time and cost savings (Abrams & Streit, 1986; Milheim, 1989). That is, simulated field experiences are available at any time, saving the time and travel costs associated with actual field experience. This is similar to claims made by military users of interactive-video training courseware (Ramsberger, Harris, Knerr, & Hopwood, 1985). Because users' experiences will be the same, or similar (depending on the nature of the simulation and what choices students make within the programs), they will have common experiences that lead more easily to classroom discussion (Hasselbring et al., 1987; Walkley & Kelley, 1989). Simulated field work may reduce anxiety because users know they can try ideas without risking failure with “real” students or worrying about possible negative effects from unacceptable actions (Gropper, 1983). Therefore, simulations using interactive video potentially provide an important, “risk-free,” stepping stone from non-experienced student to classroom professional. With these advantages, interactive-video computer-based simulations are promising tools to help prepare educators.

Policy and institutional support for agroforestry: an analysis of two Ecuadorian case studies

Institutional and policy issues are now recognized as high priority items in agroforestry research. However, such studies based on actual field experiences seldom seem to have been undertaken. To help address this deficiency, a study was undertaken in Ecuador to evaluate institutional and policy impacts on agroforestry dissemination using two field projects as case studies. The projects were in contrasting ecological locations: the Amazonian lowlands (the Coca Agroforestry Project), and the Andean highlands (the PROMUSTA project). The impact of policy and institutional constraints (such as land tenure, research and extension support, marketing and pricing, and credit) on the implementation of these projects was assessed based on interviews with farmers and project officials as well as analyses of secondary data. The Coca project was found to be adversely impacted by the lack of extension, product marketing, and credit availability. The principal institutional constraints for the Andean project included legal obstacles to farm-land procurement, inadequate extension, little state-financial assistance, and limited affordable credit. The relevance of these issues was location specific: while access to land was not a serious constraint in the lowlands, it was a major issue in the highlands. The study validates the premise that policy and institutional evaluations should become an essential component of design and implementation of agroforestry projects. Although the components of a sound policy framework might be similar in most developing-country situations, it may not be possible to evolve universally applicable procedures for agroforestry-policy formulation because of the location-specificity of the promoted systems and the institutional issue related to their adoption.

PWSCC in the tube expansion zone - an overview

Most of the PWR Steam Generators (SG) with tubes in Inconel 600 alloy are affected by Primary Water Stress Corrosion Cracking (PWSCC) in the Expansion Zone (mainly the Roll Transition) of tubes mechanically expanded in the tube sheet. After a description of the defect mechanism and characterization methods, the paper reviews the various measures that can be used to prevent the problem. In-Service Inspection results are presented to illustrate the actual field experience; prediction tools are available to forecast the further SG degradation. Degraded tubes are eventually removed from service; this plugging policy undergoes presently a major evolution towards a mechanism specific approach, taking into account both structural and leakage requirements. The paper reviews various repair techniques that can be used as an alternate to plugging. Ultimately repair has to be weighed against SG replacement within a comprehensive problem management approach.

The Potential of Pulse-Jet Baghouses for Utility Boilers. Part 1: A Worldwide Survey of Users

Pulse-jet fabric filters (PJFFs) are widely used in U.S. industrial boiler applications and in utility and industrial boilers abroad. Their smaller size and reduced cost relative to more conventional baghouses make PJFFs appear to be a particularly attractive particulate control option for utility boilers. This paper summarizes the results of a survey co-funded by the Electric Power Research Institute and the Canadian Electric Association to characterize the performance of and operating experiences with PJFFs applied to coal-fired boilers. The survey involved site visits to interview technical and plant personnel involved in the design, installation and day-to-day operation of PJFFs worldwide. Actual field experiences with PJFF performance in terms of outlet emissions, pressure drop and bag life for different types of pulse-jet cleaning methods, fabrics and boilers are compared. The second part of this series will present results of pilot PJFF studies conducted by EPRI at different U.S. utility sites on d...

American Electric Power experience with loop switching in EHV stations using air-break disconnect switches

The authors focus on the loop switching operation inside a substation, which is called local loop switching. Within the local loop there are circuit breakers and disconnect switches that can be used to perform a loop switching operation. The interrupting duty of the air-break disconnect switch is calculated theoretically as a function of the station bus physical arrangement and current flow pattern inside the station. The loop switching capability is experimentally determined for two types of 765 kV air-break disconnect switches. The benefits of loop switching performed with air-break disconnect switches inside electrical substations are illustrated by three examples of actual field experience. The switching procedure involved in these examples is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The acquisition and integration of route knowledge in an unfamiliar neighborhood

This paper investigates the acquisition of neighborhood route knowledge by children of ages 9–12. Subjects were exposed to two routes through an unfamiliar suburban neighborhood, with five learning trials undertaken on each route. One route was acquired by actual field experience, while the other was acquired by viewing a video tape. Route knowledge acquisition was tested by performance on navigation, sketch mapping, and scene recognition tasks. Mode of experience had little effect on recognition performance; however, navigation performance following five video trials was inferior and approximated that of children with only one trial of field experience. These data support the differentiation of knowledge types and the need to engage in route navigation to proceduralize such knowledge.

Post-mortems-methodology and experiences

A methodology for preparing and conducting post-mortems for software development projects is presented. Based on the continuous process improvement concept, post-mortems are systematic reviews of a product's quality and the quality of the associated processes that produce it. The intent is to learn both what worked well and what could be improved. Three types of postmortem have evolved, each focusing on particular aspects of the software development process. The planning postmortem covers requirements specification and work program definition. The design verification postmortem includes design, unit test, system verification, and first office application activities. The field post-mortem focuses on actual field experience. The post-mortem methodology has been in use for several years and has been found to be a very effective organizational learning tool and source for many software quality improvement ideas. Specific examples of what has been and can be learned are included. The evolution of the post-mortem is discussed, along with possible metrics for evaluating the effectiveness of postmortems. >

The Geographic Distribution of Intensity and Frequency of Freeze-Thaw Cycles

The correlation of laboratory freeze-thaw tests to actual field exposure has long been an item of interest for those persons involved in evaluation of rock as an engineering and construction material. Attempts at using the laboratory freeze-thaw durability test to predict the serviceability or performance of rock as a building material often do not correlate with actual field experience. Part of this lack of correlation is attributable to inaccurate measurement and incomplete understanding of field exposure. This, in turn, implies that testing procedures do not accurately reflect the conditions of field exposure. The purpose of this paper is to provide a better understanding of the conditions and variables of field freeze-thaw exposure. It is only through a careful analysis of these variables and conditions that a more suitable laboratory test may be designed.

Design of a resident in-field experience for an emergency medicine residency curriculum

The importance of a resident training in emergency medical services (EMS) is emphasized by the recent development of formal curricula that attempt to prepare the graduating emergency physician for a leadership role in the EMS community. Despite the delineation of specific goals and objectives of such training, actual field exposure and experience in prehospital care have remained voluntary and often sporadic. We designed a resident experience for on-scene attendance at selected incidents and surveyed our residents for their opinion of the curriculum. We also examined field records to determine the nature of field calls and the numbers and types of procedures carried out by second- and third-year residents. During the six-month review period, 158 cardiac arrests were attended, 58 difficult intubations were carried out, 49 central or peripheral lines were started, and 24 severely injured patients were treated on-scene or en route to the hospital. The average response time by the resident to the scene was nine minutes, and the average on-scene time was 20 minutes. Residents completing the survey indicated support for the program and agreed that it has enriched their learning experience. Combined with an air (helicopter and fixed-wing) and ground critical care transport service, the EMS in-field experience has provided opportunities for residents to make rapid decisions, to appreciate the field team's perspective, to report concisely and clearly to colleagues, and to practice required advanced skills. We believe that a formal, planned, and balanced in-field curriculum can afford an opportunity for unique educational experiences that will enrich the graduate program in emergency medicine.

The development and use of large scale information systems for plant operating experience and component failure data

The design of pressure components for very high levels of structural reliability involves taking account of three types of variations or uncertainties. These include (1) the normal range of materials properties measured under laboratory conditions; (2) the normal or calculated ranges of load and duty cycles; (3) the added range of variation in properties due to fabrication, environment, and aging, and the possible added range of load or duty cycles due to infrequent transient conditions. Direct testing and analysis can reasonably attain confidence of failure rates of 10 −3/yr. The assurance of still lower rates - to 10 −6/yr, desirable for nuclear applications, benefits from a combination of testing and analysis, but augmented by intensive use of actual field experience of failures or degradation found by inspection. The scopes and uses of two major data systems are described. These are (1) the Significant Events Evaluation and Information Network (SEE-IN), and (2) the Nuclear Plant Reliability Data System (NPRDS). Together these systems cover the cumulative experience of ∼1,000 unit-years of nuclear plant operation. Uses of these systems to refine operations, maintenance, rework, and in some cases design or specifications, is described.

Burnthrough Of GIS Enclosure Due To Power FaulT ARCS

Enclosure burnthrough in gas insulated substations due to power arcs has to be prevented for personnel safety and operational reasons. Many studies on burnthrough have been published giving different experimental results. Thus, the estimation of burnthrough times on the basis of this published data seems difficult. This paper summarizes the present status of experimental and theoretical studies on burnthrough and shows, that the data appears more homogeneous if the experimental conditions are considered. Formulae based on theoretical analysis seem less practicable than those empirically found. One of these empirical formulae gives reliable and conservative estimates of burnthrough times in actual equipment and is recommended for general use. In the discussion of actual field experience it is emphasized that auto-reclosing in GIS increases the risk of burnthrough and thus the practice should be very carefully reviewed. Areas requiring further investigations are indicated.

Bibliography of Literature on Steam Turbine-Generator Control Systems IEEE Committee Report

The bibliography of literature on steam turbine-generator control systems was conceived during the committee work that revised the recommended practice known as IEEE 122 Functional and Performance Characteristics of Control Systems for Steam Turbine-Generator Units. To provide the user of the standard with a tool for educational enhancement and development, it was decided by the committee that a bibliography of current literature should be developed. The bibliography was developed utilizing computer searching techniques currently available through many Industrial Libraries, Universities, and Public Libraries. The items listed in this bibliography have been divided into ten separate groups in order to focus attention on ten specific aspects of turbine control systems. The list begins with papers on basic design features of steam turbines and their associated hardware, proceeds through papers dealing with control requirements and controller design and performance under various operating conditions, and ends up with papers which report actual field experience in this subject area. The bibliography includes references over the period essentially from 1970 to 1981 with a few preceding that period.

Design of reverse osmosis systems for commercial seawater desalination

The prime objective of any commercial desalination process is to produce desalted water at the lowest cost per gallon. This fundamental cost criterion is reviewed within the constraints of water quality, ease of operation, reliability and environmental impact. Problem areas common to all desalination systems include energy requirements, prefiltration, silt, corrosion, precipitation, maintenance and installation. Design criteria are examined for each of these problem areas. Next, a seawater Reverse Osmosis design is reviewed. The actual field experience of two years of commercial operation at various locations is summarized. The engineering and experience presented is applicable to large urban, installations as well as small remote systems both in developing and highly industrial cultures.

Factors Affecting Cuttings Removal During Rotary Drilling

Abstract Laboratory tests conducted by the author, together with actual field experience in Canada, have indicated the magnitude of some of the factors affecting ability for drilling mud to clean the hole. A correlation was observed between funnel viscosity and particle slip velocity. A relationship was also observed between the Bingham yield value of the mud and the particle slip velocity. Laboratory tests indicated little change in slip velocity with funnel viscosities up to about 80 sec/qt or to yield values of about 15 lb/100 sq ft . The slip velocity of the particles studied varied from 160 ft/min with water to nearly zero for high mud viscosities. Increasing the mud density, creating laminar annular mud flow or rotating the drill pipe may also improve the carrying capacity of mud. Field tests indicated that during fast upper-hole drilling, the rate of cutting removal must be sufficient to maintain the concentration of cuttings in the annulus at less than 5 percent by volume to prevent balled-up drill collars and stuck drill pipe. Introduction In the Mid-Continent area, hole cleaning during rotary drilling normally involves the use of low-density drilling muds with funnel viscosities varying from 26 to 80 sec/qt. However, frequently it is necessary to raise the mud viscosity in excess of 200 sec/qt to clean the hole. In addition, field experience has indicated that during very fast upper-hole drilling, annular mud velocities considerably in excess of the maximum slip velocity of the cuttings (normally considered to be 120 to 150 ft/min) are necessary to prevent balling the bit and drill collars. In view of these variations in mud properties and circulation rates necessary to clean the wellbore, a study of factors affecting hole cleaning and the relative magnitude of each was undertaken. The study was also prompted by the knowledge that a drilling mud with properties close to those of water would drill at rates several times that of a viscous mud. The carrying capacity of these near-water muds was not clearly understood, however, and many drillers were reluctant to use them. Discussion: EFFECT OF MUD PROPERTIES ON DRILLING RATE The effect of mud properties on drilling rate has been studied by a number of investigators. It is clear from their work that mud properties close to those of water will significantly improve drilling rate and bit life. If the water-type mud will also effectively clean the hole and cause no logging or formation impairment problems, the choice of an appropriate drilling fluid is clear-use water. Often, however, a water-type drilling fluid is not capable of effectively cleaning the hole. THEORY OF PARTICLE SETTLING The forces acting on a particle that is allowed to settle through a fluid quickly reach equilibrium, and the particle settles at some constant velocity referred to as the slip velocity. The slip velocity of any particle depends upon a number of factors such as density and viscosity of the fluid, the volume, specific gravity, shape and roughness of the particle, and upon the shape and area of the projected face of the particle at right angles to the direction of relative fluid solid movement. Brown' expressed this relationship for spheres in Newtonian fluids in the following equation. vs= ........................................(1) where vs= slip velocityDs= diameter of sphereps= density of spherept= density of liquidfD= friction factorg= constant. The friction factor fD varies as the size, shape. surface roughness and slip velocity of the body, and as the density and viscosity of the fluid varies. Waddel found experimentally that where dynamic similarity exists, f, was a function of the particle Reynolds number (Nrc) of the sphere (Fig. 1). Fig. 1 shows that f, for spheres varies from over 10 for low NRe. numbers to 0.44 for NRe over 600.

Cooling Water Inhibitor Performance

Abstract Corrosion inhibitors in open recirculating cooling water systems require rapid and complete film formation for maximum effectiveness. The protective film is established on clean surfaces by initial treatment with inhibitor at high dosage levels. Protection then can be maintained by continuous treatment at substantially lower levels. If operational difficulties should cause loss of the protective film, low level treatment after the film has been lost may result in severely increased corrosion and deposition. Laboratory corrosion, deposition and consumption studies with polyphosphate-based and chromate-based inhibitors illustrate the advantages of high level start-up and low level maintenance treatments. These data are confirmed by actual field experiences. 5.8.1

SEISMIC REFRACTION WITH VARIABLE VELOCITY

The results of an investigation of methods of interpreting and calculating the propagation of seismic waves with variable velocity in contrast to an assumed constant velocity is presented. One of the major purposes of this study is to establish a calculation method for use in seismic refraction work that can be applied to existing types of alluvia and similar geologic formations. In addition to presenting the necessary tables and graphs used for such computations, two examples from actual field experience are presented.

Interpretation of Well Test Data in Gas-condensate Fields

Abstract The operation of gas-condensate fields is comparatively new and involvesphysical principles with which the industry was not previously familiar. It hasbeen necessary to devise methods for testing gas-condensate wells and tocorrelate laboratory and field data. In this paper new methods are advanced forinterpreting well G.P.M. t tests whereby dilution by dry gas can be estimatedand information supplied on revaporization of condensates by dry gas.Inaccuracies in well test data are discussed. Changes in flow rates can causechanges in the G.P.M. of the effluent and it may take some time for a well tobecome stabilized after an important change in flow rate. Retrograde tests asusually conducted cannot be directly compared with field G.P.M. data, becausethe retrograde tests usually include solution gas in the condensates, which arereported on the cumulative basis whereas field data (G.P.M.) usually reportpentanes plus on a rate or instantaneous basis. Introduction Though long known to physicists, the phenomena of retrograde condensationbecame known to the oil and gas industry only in recent years, when deeperdrilling disclosed that the behavior of vapors under changing pressures wasdifferent in high-pressure reservoirs than under the low-pressure operationswith which the industry was familiar. These deep, high-pressure reservoirs inwhich condensation and vaporization behaved inversely to the accustomed mannerbecame known as "gasdistillate," or preferably "gas-condensate"fields. Partly to prevent precipitation and retention of liquids in thereservoir, but still more to prevent the waste of residue gas, the operationknown as "recycling," or preferably "cycling," was instituted, in which the residue gas is reinjected into the reservoir, thus maintainingpressure and driving the wet gas to the producing wells. For lack of field experience to serve as a guide, the industry had to assumethat theory and laboratory experiments could accurately forecast retrogradebehaviors in operating these gas-condensate fields, but it is obvious thatthese assumptions should be checked at the first opportunities against actualfield experience. To make such checks, it is necessary to accumulate a largequantity of reliable field data, but experience has shown that it is difficultto obtain reliable field data and that the laboratory data as usually presentedare not in directly comparable form. The problems of correlation involve thecomplex phase behavior on the one hand, and a knowledge of field data and avisualization of underground conditions on the other hand. This paper is anapproach from field experience. The purposes of this article are to discuss the sources of uncertainty in thedata and to present methods of analyzing, interpreting and correlatinglaboratory and field data. Data mostly from lower Gulf Coast fields arepresented, from which some conclusions can be derived, but better data frommore sources than those available to the writer will be required beforesatisfactory answers to many questions can be obtained. This paper is presentedto stimulate the analysis and publication of data from other fields, thereexamination of field and laboratory methods, and the taking of more completeand reliable field tests. For these purposes, the writer presents somespeculations that otherwise would not be appropriate. T.P. 2053