Field Verification Tests Research Articles

The strain field method for structural damage identification using Brillouin optical fibersensing

The theory of the strain field (SF) method using Brillouin optical fiber sensing(BOFS) is proposed for structural damage identification in this paper. Field testverification of this method was carried out by implementing a destructive loadingtest to an existing prestressed concrete bridge. A series of structural damagescenarios were thus produced for identification. A sub-matrix featuring the damagescenarios was first extracted from the space–time matrix to obtain the strain fielddistribution in space–time coordinates. Furthermore, other feature extractionoperations, including row vector extraction, column vector extraction and boundaryextraction, were performed to characterize the structural damage behavior anddamage evolution patterns. Finally, damage localization and quantification weresuccessfully implemented in both space and time domains in terms of a damageindex vector array. The investigation results demonstrated the SF method usingBOFS is a feasible and efficient approach for structural damage identification.

Crucial effect of system compliance on the maximum stress estimation in the hydrofracturing method: Theoretical considerations and field-test verification

Abstract Why do the currently available data sets from field hydrofracturing tests indicate that the measured re-opening pressure lies close to the shut-in pressure far more often than can reasonably be expected? In order to explain such a strange phenomenon, it is necessary to take into consideration two additional factors, those of (1) a residual aperture of fracture and (2) hydraulic compliance of the test equipment, both of which are ignored in the conventional theory of hydraulic fracturing. The residual aperture causes pressure penetration into the fracture prior to opening, and its effect is to reduce the re-opening pressure by a factor of two from the value expected when the conventional theory is used. The conventional theory implies that the fracture always begins to open at a borehole pressure less than the shut-in pressure. However, due to the effect of large hydraulic compliance, the reopening pressure measured in the conventional manner becomes larger than the true reopening pressure and approaches the shut-in pressure. Contrary to this, the reopening pressure measured using the test equipment with sufficiently small compliance represents a good estimate of the true reopening pressure. This pressure is related to the maximum horizontal stress S H, and its measured value allows us to estimate the value of S H.

Field Verification of an Advanced High Side Voltage Control at a Hydro Power Station

An advanced high side voltage control (HSVC) that can improve power system stability by adding supplemental control to conventional generator excitation systems has been developed. Since the introduction of this advanced HSVC at the IEEE PES 2000 Summer Meeting, additional development has further improved the advanced HSVC as reported in a companion paper. This paper describes field verification results for the HSVC that were carried out on a hydro power plant of the U.S. Army Corps of Engineers on the Columbia River at The Dalles. The advanced HSVC was temporarily added to the existing digital automatic voltage regulators (AVRs) of two generators in a 22-machine hydro power plant. Various tests, such as confirmation of droop, performance of the cross-current suppression function, switching on and off of a nearby capacitor bank, and others, were successfully carried out. It was confirmed through these field verification tests that the advanced HSVC displayed beneficial impacts on voltage control and system stability as compared to a conventional AVR.

Dynamic Analysis and Ride Quality Evaluation of Railway Vehicles – Numerical Simulation and Field Test Verification

AbstractA rather complete dynamic model with special emphases on nonlinear conicity and creep force and in consideration of random irregularity of rail profile is proposed to simulate the response and investigate the ride quality of railway vehicles. The CP341 vehicle that will soon be used in Taipei Rapid Transit System is considered in particular as the studied role model. Some of the field test data carried out for this type of vehicle are revealed as well and used for the verification of the proposed model. Both simulation and test results show that the resonant frequency of the studied vehicle is in the range of 0.6∼1 Hz, and the one-third octave root-mean-square acceleration curves of the vehicle in all studied cases meet the ride quality criteria set for the mass rapid transit vehicle systems. It is observed that the secondary suspension of the vehicle has the low frequency filtering property and the primary suspension has high frequency characteristics. A poorer ride quality in vertical direction rather than in lateral direction is also confirmed in the study. It is concluded that the proposed model can be used to simulate the dynamic response and evaluate the ride quality of any railway vehicle.

配電線電圧変動補償装置(直列型)の実線路検証

配電線電圧変動補償装置(直列型)の実線路検証

On‐site gas chromatographic determination of explosives in soils

AbstractOn‐site determination of nitroaromatic and nitramine residues in soils was performed using a field‐portable gas chromatograph (GC) equipped with a thermionic ionization detector selective for compounds with nitro functional groups. Soil samples were extracted with acetone. A 1‐μl volume of the filtered extract was manually injected into the GC, allowing for the rapid determination of the suite of explosives that often coexist in explosives‐contaminated soils at military training facilities and other defense‐related sites. Good agreement was established for the concentrations of several explosives when results obtained using this method of analysis were compared with those from either high‐performance liquid chromatography (Method 8330) or GC electron capture (Method 8095) analysis. Comparisons were performed for sample extracts and for soil subsample replicates distributed for on‐site analysis during a field verification test performed under the auspices of the U.S. Environmental Protection Agency's Environmental Technology Verification Program. This on‐site GC method for the determination of explosives residues in soils is well suited for dynamic site characterization activities. © 2001 John Wiley & Sons, Inc. Field Analyt Chem Technol 5: 228–238, 2001

Modelling of the physical behaviour of clay barriers close to water saturation

The physical properties of bentonite-based buffer materials for nuclear waste repositories have been investigated by a number of different laboratory tests. These tests have yielded a material model that is valid for conditions close to water saturation and is useful for describing: (a) the stress, strain and volume change behaviour; (b) the pore pressure and flow of water; and (c) the thermal and thermomechanical response. The material model is based on the Drucker-Prager Plasticity model and a Porous Elastic Model. The effective stress concept and Darcy's law are applied and the swelling/consolidation and thermomechanical processes are coupled according to the separate mechanical properties of the pore water, the solids and the clay skeleton. The model can be used by the finite-element program ABAQUS. The model has been tested in several laboratory and field verification tests. Comparison between measured and calculated behaviour shows that the general behaviour is described properly and several calculations of different scenarios have been made for the Swedish KBS 3 concept. However, certain processes, like the hysteresis effect at consolidation/swelling, the curved stress-strain relation at shearing, and the curved failure envelope, are not modelled in a perfectly accurate way and an improved material model is proposed here. It combines the behaviour of the Cam-clay model on the wet side with the more relevant plastic behaviour of a modified Drucker-Prager model with a curved failure envelope and the possibility to introduce strain softening after failure. The paper presents some laboratory results that are the basis of the first model. It also shows the application of the model to finite-element calculations of some laboratory tests. Comparisons between the calculations and measured results expose some disadvantages of the model and a concept for an improved model is suggested.

Development of VBO-free large capacity light-triggered thyristor valve

Following the recent development of 6 kV class VBO (voltage break-over)-free light-triggered thyristors (LTTs) in Japan, a field verification test has been conducted by applying these thyristors to an actual 100 MVA class SVC valve, and satisfactory results were obtained. The authors describe the characteristics of the VBO-free large-capacity LTTs, the effects that can be expected when it is applied to SVC or HVDC valves, design and manufacturing, the results of factory tests for the SVC and valve, and the results of a verification test in the field. >

Overview of LASL Oil Shale Program: ABSTRACT

The Los Alamos Scientific Laboratory (LASL) is involved in a broad spectrum of oil shale-related activities for the Department of Energy (DOE), including the bed preparation design of a modified in-situ retort. This aspect of oil shale research has been identified by the DOE as one of the limiting technologies impeding commercial, in-situ development of oil shale. The retort bed must have uniform particle size, permeability, and void distributions to allow proper retorting and optimum resource recovery. Controlled fracturing using chemical explosives and carefully designed blasting schemes are the only feasible methods to attain this distribution. Our approach to the bed preparation problem is a coordinated research program of explosives characterization, dynamic rock mechanics, predictive computer modeling, and field verification tests. The program is designed to develop the predictive fracturing capability required for the optimum rubbling of the shale. It takes advantage of the large computing facilities at Los Alamos and the considerable expertise in explosives and computer hydrocodes developed here for other energy and national defense programs. As these codes are developed for oil shale and refined, they are tested with field verification experiments. Tests with up to four boreholes and single-decked charges conducted at the Colony Mine in Colorado in conjunction with ARCO and TOSCO, have demonstrated the ability to predict rock behavior. Larger experiments with more boreholes and decked charges will be done at the Anvil Points Mine near Rifle, Colorado. These field tests will calibrate the fracture modeling cod s and confirm their validity to predict explosive fracturing, including the effects of existing joints and fractures in the oil shale. The experiments will also include fluid flow tests to verify the three-dimensional models of multiphase flow that are under development at LASL. End_of_Article - Last_Page 961------------

Prediction Method for Buried Pipeline Voltages Due to 60 Hz AC Inductive Coupling Part II--Field test Verification

The results of field tests on a buried, 34-inch diameter gas pipeline adjacent to a 525 kV ac power transmission line for 54 miles are discussed. Comparison is made between measured inductive coupling data and predictions obtained using the theory developed in part I of this paper. An excellent agreement of the predicted and measured results is shown for the location and magnitude of all induced voltage peaks on the pipeline.