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The influence of aging treatment on microstructure and corrosion fatigue crack growth (CFCG) behavior of oil-grade nickel-base alloy 718 is investigated. The average grain size of alloy 718 increases after aging treatment. Isolated platelet δ phases are precipitated at some of the grain boundaries in aged specimens. The one-step aged specimen shows a uniform distribution of fine spherical γ′ and elongated γ″ precipitates. However, the two-step aged sample shows much finer γ″ precipitates. Aging treatment leads to lower CFCG rates of alloy 718. Nevertheless, no visible difference of CFCG rates is observed between one-step aged and two-step aged specimens.

The effect of corrosive environment on corrosion fatigue crack growth (CFCG) behavior of oil-grade nickel-base alloy 718 is studied. The results demonstrate that there is no obvious effect of 3.5 wt.% NaCl solution at RT, 50 °C and 80 °C on CGCG rates while 21 wt.% NaCl solution at 80 °C produces a deleterious effect on CFCG rates compared to the ones tested in air. Potentiodynamic polarization results show that alloy 718 exhibits passive behavior in 3.5 wt.% NaCl solution, while pitting corrosion resistance decreases with increasing solution temperature. Nevertheless, alloy 718 shows active corrosion behavior in 21 wt.% NaCl solution at 80 °C.

Innovative and coordinated strategies to address weight bias among health professionals are urgently needed. We conducted a systematic literature review of empirical peer-reviewed published studies to assess the impact of interventions designed to reduce weight bias in students or professionals in a health-related field. Combination sets of keywords based on three themes (1: weight bias/stigma; 2: obesity/overweight; 3: health professional) were searched within nine databases. Our search yielded 1447 individual records, of which 17 intervention studies satisfied the inclusion criteria. Most studies (n = 15) included medical, dietetic, health promotion, psychology and kinesiology students, while the minority included practicing health professionals (n = 2). Studies utilized various bias-reduction strategies. Many studies had methodological weaknesses, including short assessment periods, lack of randomization, lack of control group and small sample sizes. Although many studies reported changes in health professionals' beliefs and knowledge about obesity aetiology, evidence of effectiveness is poor, and long-term effects of intervention strategies on weight bias reduction remain unknown. The findings highlight the lack of experimental research to reduce weight bias among health professionals. Although changes in practice will likely require multiple strategies in various sectors, well-designed trials are needed to test the impact of interventions to decrease weight bias in healthcare settings.

The contrawound toroidal helical antenna (CTHA), a novel low-profile antenna, is a bifilar antenna with four terminal connections. The two filaments of the antenna can be thought of as a two-wire transmission line whose resonances are determined by the boundary conditions present at the ends of the line. The CTHA is then approximated by a circular array of vertical loops for certain resonance modes. This structural approximation is used in an analytical approach to estimate the general shape of the radiation pattern of the CTHA for these cases. The analytical results are compared with simulation. Relatively good agreement was found, validating the structural approximation for rough pattern estimations.

We introduce a new application of artificial neural network technology in the characterization of reservoir heterogeneity. Different reservoir properties, such as porosity, permeability and fluid saturation, in highly heterogeneous formations can be predicted with good accuracy using information deduced from readily available geophysical well logs. The methodology by which this is carried out is based on the intelligent and adaptive pattern recognition capabilities of an artificial neural network (three-layer feed forward, back propagation). The need for expensive processes to acquire porosity, permeability and fluid saturation data (such as well testing and extensive coring of the formation) may therefore be greatly reduced. Examples of several neural networks developed during this study are presented.

Presents a numerical study related to the application of a neural network or neural observer for state estimation purposes in the overall problem of active control of structural vibrations. The application of this type of estimation structure presents several advantages relative to classic approaches, such as any type of observer or Kalman filter. The results related to the training session and to the numerical implementation of the state estimation for a vibrating cantilevered aluminum beam are presented. The influence of different parameters, such as learning rate, number of hidden layers, number of processing elements for each hidden layer, and size of the input data pattern on the training section is shown.

The development of an autonomous mobile robot for use in underground mines is described. The navigation scheme combines elements of both hierarchical control and reactive or subsumptive-type control. The robot navigates by sensing the environment and selecting a navigational mode that is appropriate to the circumstances and to the robot's mission. Examples of navigational modes are wall following, collision avoidance and homing. The modes are implemented in modules formed by combinations of neural network processors and conventional control algorithms. The overall control system architecture and the navigational strategies of the experimental robot vehicle are also described. >

The effect of lightning poses a significant problem to computer systems and electronic equipment used in surface and underground mines. Conventional protection schemes such as shielding, insulation, and filtering circuits are not adequate. The field-induced voltages and currents cause transients that can create an upset in digital or computer systems. Two effective approaches are proposed to detect and recover from transient faults when monitoring, processing, or controlling critical mining operations. >

The Mine Management Support System which is being developed as a knowledge-based expert system for better management of underground coal mines, is presented. Concentrating on capturing the complex body of knowledge needed to enhance efficient management of a mine, it will encompass information and preferred rules on work scheduling, work practices, regulations impinging on the accomplishment of work, responses to operating problems, and the labor-management work agreement. Different components of the mine system, modeled using an object-oriented layering technique, are displayed graphically to aid in coordinating work plans and to present locations of equipment, supplies, and proposed subsystem components. >

This paper describes research known as "Flexible Automation in Mines" (FAM) which explored the appliation of neural network technology to the navigation of a freeranging robotic vehicle in a mining environment. Numerous applications for neural networks were identified, developed and testing during the FAM project. Some applications were found to hold significant promise while others were deemed inappropriate. In this paper, we place in perspective the individual projects and findings from the entire five-year program, and present the conclusions and recommendations resulting from this work.

We present results of a study of the static characteristics of regenerative amplifiers based on Mach-Zehnder interferometers with semiconductor optical amplifiers in each arm. Specifically we consider a series of regenerative amplifiers and single regenerative amplifiers with feedback. Small amounts of feedback lead to produce hysteresis in the transfer functions of the regenerators. Including an SOA in the feedback loop allows the feedback to be controlled optically and leads to an all-optical latch design.

The authors describe the Mine Management Support System, a knowledge-based expert system being developed for better management of underground coal mines. The program will encompass information and preferred rules on work scheduling, work practices, regulations impinging on the accomplishment of work, responses to operating problems, and the labor-management work agreement. Different components of the mine system, modeled using an object-oriented layering technique, will be displayed graphically to aid in coordinating work plans and to present locations of equipment, supplies, and proposed subsystem components. >

Based on the idea of using heterogeneous processing units (PUs) in a network, a variation of the backpropagation (BP) learning algorithm is presented. Three parameters, which are adjustable like connection weights, are incorporated into each PU to increase its autonomous capability by enhancing the output function. The extended BP learning algorithm thus is developed by updating the three parameters as well as connection weights. The extended BP is intended not only to improve the learning speed, but also to reduce the occurrence of local minima. The algorithm has been intensively tested on the XOR problem. By carefully choosing learning rates, results show that the extended BP appears to have advantages over the standard BP in terms of faster learning speed and fewer local minima. >

Research at West Virginia University directed at developing autonomous mobile robot navigation systems for use in underground mines is discussed. One of the focal points has been the exploration of applications for neural network technology in the navigation context. An overview of the various experiments as they relate to each other is given along with some of the conclusions drawn about neural network applications resulting from this work. The networks have excelled in applications involving pattern recognition such as the neural area recognition system, the landmark recognition system, and the noise distribution function estimator, in these applications the difficulties encountered in configuring the networks by trial and error and the slow network training process were outweighed by the performance the networks eventually provided in difficult signal processing tasks. In other applications such as the early steering control system and the neural position estimator the performance of the networks has proven inferior to what is believed could have been achieved more easily by conventional means. >

This research explores the use of Neural Networks (NNs) to implement Automatic Fingerprint Matching (AFM) system. A new three stage architecture, consisting of a preprocessor, feature finder, and matcher stage, is shown to be successful for fingerprint matching. The NN-based AFM system used 20 fingerprints as its training set and 80 fingerprints as its test set. By dividing a fingerprint into 256 16 x 16 pixel blocks, the achieved success matching rates are 95% on the training set and 93.75% on the test set. The Feature Finder based on the Counter Propagation NN realized a high dimension reduction ratio of 256: 1. It finds a feature vector of 256 bytes from a digitized fingerprint of 512 x 512 pixels with 8-bit grayscale. This system also achieved 91.67% matching success m the cross-iferenced fingerprints. Keywords: neural networks, fingerprints, automatic fingerprint matching systems

The authors formulate the training problem for three-layer feedforward neural nets based on the well known linear algebra of D. Rumelhart et al. (1986). Then, they develop two estimation algorithms, called the forward estimation algorithm and the recurrent estimation algorithm, to estimate the initial weights. The basic idea is to set the initial weights space as close as possible to a global minimum before training, consequently reducing the training time. It is theoretically and empirically shown that a training procedure is unnecessary if the number of hidden units is equal to or greater than the number of training patterns minus one. Simulations were conducted for several problems. Results showed that the training speed is significantly improved by both initial weight estimation algorithms. >

The concept of backpropagation training with a gradual increase in accuracy is presented. The concept may be incorporated with the basic backpropagation algorithm or with the backpropagation algorithm with a momentum weight change to result in significant speed improvements without increasing the size of the network or requiring additional support hardware. Experimental results show that the proposed modification, on the average, doubles the convergence rate of the backpropagation algorithm and the backpropagation algorithm with a momentum weight change. >

Naive listeners arc readily able to differentiate spontaneously produced speech from speech produced from text. The prior studies have employed lexically, syntactically, and thematically identical pairs of natural sentences extracted from brief fluent monologs (< 40 s in duration), finding relatively high levels of performance in tests of perceptual differentiation. To determine which attributes of the speech signal contribute to the perceptual differentiation of spontaneous and prepared speech, the present study manipulated several likely acoustic parameters employing techniques of speech synthesis. One condition reduced the frequency variation of the synthetic copies of the utterances to a monotone. A second condition removed the segmental attributes (consonants and vowels) from the sentence pairs by low‐pass filtering of the synthetic signals, leaving metrical and fundamental frequency variation intact. The final condition neutralized both the segmental and phonatory attributes, leaving only metrical p...

In the testing of mine monitoring systems, a software package was developed for the mine monitoring test facility designed at West Virginia University. The software establishes delay times of sensor input to annunciation for single alarms and multiple simultaneous alarms. The alarm measurement techniques for the test fixture are described, as is the software developed to analyze and graph monitoring system response data. Also included is the analysis capability of the facility, the criteria for evaluating mine monitoring systems, and typical test data from a sample system.

A brief summary of the history of university involvement in communications and monitoring in underground coal mines is presented, beginning with the first federal appropriation of funds in 1970 under the Coal Mine Health and Safety Act of 1969 and continuing through the first half of 1985. Insight is provided into significant trendsetting work done by these universities. The first US mine monitoring project, the first US minewide monitoring system, and the first distributed microprocessor-based mine monitor system are discussed. >

Microprocessor reliability in coal mine monitoring applications has become increasingly important in recent years. This has been true not only for the mining industry, but the computer industry as well. Processor maintenance self-diagnostics have been commonly utilized for microcomputer systems. However, in the case of a microprocessor used in a critical monitor/control environment, small memory and little free processing time limits the use of these diagnostics on a continuous basis. In the past, maintenance diagnostics have been very exhaustive for minicomputer systems and execution time can be quite long. These were primarily used on an infrequent aperiodic basis by a maintenance technician. Normal system diagnostic tests are generally run at time of power up, and the system becomes operational only after successful completion. If diagnostic tests could occur automatically without user interference, such as when the system is not being heavily utilized, it is possible that failures could be found more quickly and without cata-strophic system failure. Solutions to these problems are presented as applied to a distributed microprocessor system used for testing mine monitor/control systems. A set of self-test algorithms for an 8085-based microprocessor is presented. Tests are performed on the CPU, ROM, RAM, 8251A USART, A/D, and D/A converters, and an 8253A interval timer. These self-test algorithms are not exhaustive but have been found to provide an adequate test of microprocessor validity on power up. Similar tests could and should be used on any underground monitor/control system as a minimum test.

The knowledge-based organization for the West Virginia University Face Decision Support System is given, along with the initial development of the associated inference engine. The knowledge base contains generic knowledge about underground coal mines that utilize continuous miners. A typical knowledge entry is given, and the inference engine methodology is explained. The engine utilizes this knowledge with data from monitoring systems and from interaction with the section foreman, to assist in making section management decisions and plans. >

A summary of results of the development of a methodology for identifying safety hazards inherent in underground monitoring and control equipment will be given. Under a US Bureau of Mines contract, a methodology has been developed for determining the inherent design items that affect safety hazards. Though serious consideration has already been given to the normal intrinsic safety and explosion-proof characteristics of a system, the problem may be the system itself rather than the more immediately noticeable system components. In monitoring or controlling items located in underground coal mines, the hardware reliability of a system is seldom recognized as a potential safety hazard. The software or program operating such a system is never considered as a potential safety hazard because it is, in many cases, located outside the hazardous area. In reality, electronic technology is outstripping the industry's normal view of safety and is quickly growing unseen potential safety problems. These unseen problems are a combination of hardware and computer software that must be identiried and analyzed. The methodology developed for analyzing electronic and computer-based hardware/software systems and the results of analyses completed by the West Virginia University (WVU) research team are presented. A WVU-designed distributed microprocessor-based mine environmental monitoring/control system and two other commercially available systems have undergone detailed analyses. As a result of the developing methodology, a set of design guidelines has been developed to ensure that known system design difficulties can be identified from the outset for designers of new mine monitoring/control systems.

A methodology was developed to evaluate safety and reliability of electrical mine monitoring systems. This methodology was successfully tested on three different systems. The approach used divides the system into smaller subsystems. A functional analysis is performed and a functional block diagram is drawn for each subsystem. A subsystem hazard analysis is then performed in detail on each subsystem and is followed by the constructions and analysis of fault trees. The problem of estimating failure rates for both hardware and software components is also discussed.

Field evaluation of coal mine monitoring and control systems yields data on installation and maintenance, but does not provide a full evaluation of these systems under all possible conditions. Also, the differences in installations and configurations do not allow the performance of different systems to be measured and compared. Under contract of the United States Bureau of Mines (USBM), the West Virginia University (WVU) Department of Electrical Engineering has designed criteria for evaluation of monitoring systems, and a test facility for simulation of mine conditions. This facility provides evaluation of monitoring and control systems under both normal and abnormal conditions. This paper describes the test criteria chosen, the design of the test facility, and the experiences of tests performed on mine monitoring systems to date.

Four commonly used multivalued algebras, the disjoint system of Post algebra developed by Epstein, the monotonic system of algebra called Muehldorf by some authors, the free system of algebra introduced by Braddock and Epstein, and the Herrmann system of algebra generalized here from its original three element algebra, are shown to be isomorphic. Transformations are then developed for transforming from one algebra to another. An example problem is presented to illustrate transforming from any of the above to the disjoint system of Post algebra.

The development of a rudimentary expert system design for routine and fire-driven mine ventilation, emergency escape and rescue planning, and peak power shaving is described. This description is of the first efforts toward an intelligent mine management system. Various knowledge-base constructs have been used for data validation with an interface to a standard mine fire simulation program. A natural language interface was developed to the system including the ventilation simulator program. This system serves as a vehicle for testing hypotheses generated by an expert systems.

Conventional monitoring systems use data-collection techniques to obtain sensor data about various aspects of hazardous workplaces such as coal mines and provide warnings. However, they are ill-equipped for making complex decisions involving large amounts of interrelated data. Laser/RPS, a C language-based object-oriented production system, is presented, and those programming system features that can be used to develop intelligent monitoring systems are described. Potential applications of this system to underground coal mine monitoring systems are discussed. >

A correlation for predicting dermal carcinogenicity of petroleum oils in laboratory animals has been developed using two simple analytical tests. The tests are the Food and Drug Administration test (FDA) commonly used to measure white oil purity, and a viscosity test. In the correlation, FDA is a measure of aromaticity, and viscosity is used to account for molecular weight. The FDA test alone appears to be comparable to other predictors now in use, but incorporating viscosity significantly increases the accuracy of predicting dermal carcinogenicity. A formula is proposed, using both the FDA test results and viscosity, that predicts the percentage of mice which will develop neoplastic skin tumors.

Spectral characterization of retinal images is a complex task because of the superimposed blood vessels in the retinal photographs. We have developed a segmentation technique based on a combination of edge detection and optimal thresholding operations so that the blood vessel structure can be removed from the retinal texture. The blood vessel removal method includes edge detection, tracing, and replacement with gray levels closely approximating the behavior of the background. The edge detection uses the (unsigned) first derivative of the image. The tracing routine is controlled by a mouse and follows the crests of the first derivative to trace out a length of edge. When the blood vessels are outlined, a search pattern based on finding a dark feature of given width in a light background locates those pixel elements that are clearly blood vessels. When the blood vessels are removed, they are replaced by a close approximation of the background. After the end point grey levels are determined, the vessel is painted over with a linear replacement operation, matching the background at both sides of the vessel. Spectral characterization and matching of the retinal texture can then be performed for automated detection of textural changes.

The liver and intestinal lumen are both important sites in the entero-hepatic circulation of bile salts. Lithocholate, a secondary bile acid and a potent hepatotoxin is probably detoxified in man predominantly by hepatic sulphation. Other sites may also be important. Because steroid sulphating enzymes exist throughout the gastrointestinal tract we have examined the invitro lithocholate sulphation capacity of healthy and diseased ileal and colonic mucosal samples using radio-isotope tracer techniques. Lithocholate sulphation was demonstrated in healthy and diseased ileal mucosa but not in the colonic mucosal samples studied. This new site for lithocholate metabolism acts as a further protective mechanism to prevent toxic unsulphated lithocholate reaching the liver. These findings suggest that the intestinal mucosa may have an important role in the metabolism of other bile acids.

A measurement of the underground muon decoherence function has been performed using the multiple muon events collected by the MACRO detector at the Gran Sasso National Laboratory. A detector-independent analysis is presented for different zenith regions and rock depths; this allows direct comparison with any model of hadronic interactions. The measured decoherence function is compared with the predictions of a Monte Carlo simulation based on data taken by recent collider experiments. © 1992 The American Physical Society.

We report on the first measurement of the flux of upgoing muons resulting from interactions of atmospheric neutrinos in the rock below MACRO. The ratio of the observed to the expected number of events integrated over all nadir angles is 0.73 ± .09 stat. ± .06 sys. ± .12 theor. . The flux of upgoing muons as a function of nadir angle is presented and compared to Monte Carlo expectations. At the 90% confidence level, the data are consistent with no neutrino oscillations or some possible oscillation hypothese with the parameters suggested by the Kamiokande contained-event analysis.

A study of the primary cosmic ray composition in the energy range 5ṡ1014−5ṡ1015 eV is performed through the analysis of the deep underground muons and of the e.m. component of Extensive Air Showers detected in coincidence by the MACRO and EAS-TOP experiments at the Gran Sasso Laboratory. We conclude that: a) pure proton and Iron primary beams are excluded by the experimental data; b) a fraction of nuclei heavier than Helium is necessary to explain the experimental data both below and above the knee; c) a mixed composition, obtained a priori from extrapolations of the spectra directly measured below 100 TeV, yields a reasonable account of the observations up to the knee of the primary spectrum.