334 research outputs found
Rural Facility Electric Power Quality Enhancement
Electric power disturbances are known to be more prevalent in small, isolated power systems than in larger interconnected grids which service most of the United States. This fact has given rise to a growing concern about the relative merits of different types of power conditioning equipment and their effectiveness in protecting sensitive electronics and essential loads in rural Alaska.
A study has been conducted which compares isolation transformers, voltage regulators, power conditioners, uninterruptible power supplies and indoor computer surge suppressors in their ability to suppress the various disturbances which have been measured in several Alaskan communities. These include voltage sags and surges, impulses, blackouts, frequency variations and long-term voltage abnormalities. In addition, the devices were also subjected to fast, high-magnitude impulses such as might be expected in the event of a lightning strike to or near utility distribution equipment.
The solutions for power line problems will vary for different load applications and for different rural electrical environments. The information presented in this report should prove to be valuable in making the analysis.List of Figures - viii
List of Tables - xiv
Acknowledgements - xv
Chapter 1: Electric Disturbances in Power Systems
Introduction - 16
Categorizing Electrical Disturbances - 17
Voltage Disturbances and Transients - 19
Frequency Disturbances - 22
Sources of Transients - 22
Lightning and EMP - 23
Switching - 24
Power System Noise - 25
Common Mode and Normal Mode Noise Signals - 26
Chapter 2: Power Quality in Rural Alaska
Characterizing the Village Power System - 28
The Village Electric Load - 29
Power Quality Site Surveys - 30
Rural Power Quality in Alaska - 31
Power Conditioning Requirements for Village Loads - 37
Chapter 3: Isolation, Voltage Regulation and Power Conditioning
Introduction - 39
Slow Voltage Fluctuations - 39
Voltage Regulation and Power Conditioning - 40
Ferroresonant Transformers - 40
Electronic Tap-Changing Regulators - 44
Isolation Transformers - 47
Dedicated Lines - 51
Chapter 4: Impulse Suppression
Introduction - 52
Surge Suppressors - 52
Surge Suppressor Components - 55
Component Configuration - 58
EMI/RFI Filters - 58
Standard Tests for Evaluating Surge Suppressor Performance - 60
Scope of Impulse Testing for Rural Alaska - 60
Impulse Test Equipment - 62
Test Procedure - 62
Impulse Testing Measurements - 63
Test Results - 64
Chapter 5: Uninterruptible Power Supplies
The True UPS - 68
Standby Power Systems and a New Generation of UPS - 69
UPS Backup Time - 74
UPS Testing - 74
Chapter 6: Computers and Power Problems
Introduction - 78
The Computer Tolerance Envelope - 78
Ridethrough - 80
Component Degradation and Equipment Failure - 82
Computer Power Supplies - 82
Linear Power Supplies - 83
Switching Power Supplies - 84
PC Tolerance of Powerline Disturbances - 84
Chapter 7: Comparing Power Conditioning Alternatives
Voltage Regulation - 89
Isolation - 93
Uninterruptible Power Systems - 94
Computer Surge Suppressors - 98
Summary - 98
Appendices
Appendix A: Voltage Clamping Levels of Surge Suppressors - 101
Appendix B: Voltage Clamping Levels of Power Conditioners and Uninterruptible Power Systems - 115
Appendix C: Noise Suppression of Surge Suppressors and Power Conditioners - 129
Appendix D: Waveforms and Regulating Characteristics of Power Conditioners and Uninterruptible Power Systems - 135
Appendix E: Comparison of Voltage Clamping Levels of Surge Suppressors Power Conditioners, Isolation Transformers and Uninterruptible Power Systems to High-Magnitude Impulse Voltages - 151
References - 16
Laserprobe 40Ar/39Ar dating of strain fringes: Mid-Cretaceous synconvergent orogen-parallel extension in the interior of the Sevier orogen:
[1] UV and CO2 laser-probe 40Ar/39Ar in situ analyses of phlogopite and muscovite in fibrous strain fringes from greenschist-facies metamorphic rocks document mica growth ages at temperatures lower than their closure temperatures, and therefore directly date deformation. The new dates resolve the age of the earliest ductile fabric recorded in the Raft River–Albion–Grouse Creek metamorphic core complex of Utah and Idaho. Phlogopite was dated in quartz-calcite-phlogopite strain fringes around pyrite in Pennsylvanian-Permian rocks from the Grouse Creek Mountains (Utah) using both the UV and CO2 laser probe; muscovite was dated in quartz-muscovite strain fringes around pyrite in deformed Jurassic sills from the Black Pine Mountains (Idaho) using the CO2 laser probe. Phlogopite 40Ar/39Ar ages for individual strain fringes (Grouse Creek Mountains) range from 92 Ma to 110 Ma, with the most reliable ages ranging from 101 Ma to 110 Ma (mean age, 105.0 ± 5.8 Ma). Muscovite 40Ar/39Ar ages for individual strain fringes (Black Pine Mountains) range from 97 Ma to 112 Ma (mean age, 104.7 ± 5.8 Ma). Strain fringes are associated with a subhorizontal foliation and a generally N-trending elongation lineation exhibiting components of top-to-the-north simple shear and coaxial strain accommodating N-S extension and subvertical shortening. Midcrustal northward flow at 105 (±6) Ma within the interior of the Sevier orogen, coeval with east-directed shortening in the foreland and with plate convergence, records orogen-parallel synconvergent extension. We favor gravitational relaxation of structural culminations resulting from focused crustal shortening as a driving mechanism for orogen-parallel flow
Administration of human chorionic gonadotropin at embryo transfer induced ovulation of a first-wave dominant follicle and increased progesterone and transfer pregnancy rates
Beef Cattle Research, 2011 is known as Cattlemen’s Day, 2011Embryo transfer (ET) has become more widespread in recent years as a way to improve
cattle genetics. According to the annual statistical survey of the American Embryo
Transfer Association, more than 200,000 fresh and frozen bovine embryos were
transferred in 2008. But despite advancements in reproductive technologies that have
occurred since ET was commercialized in the 1970s, industrywide pregnancy rates are
only 62.4 and 56.9% for fresh and frozen-thawed ET, respectively. Using ET helps
avoid problems from failed fertilization; however, fertilization failure has been characterized
as a relatively unimportant factor of pregnancy loss. Approximately 10% of pregnancy
failures resulted from fertilization failure and another 10% from failed embryo
development. Approximately 20 to 25% of the pregnancy loss in an ET program could
be characterized as early embryonic loss
Music Teaching in New Mexico in the Seventeenth Century: The Beginnings of Music Education in the United States
Mixture Manifold Networks: A Computationally Efficient Baseline for Inverse Modeling
We propose and show the efficacy of a new method to address generic inverse
problems. Inverse modeling is the task whereby one seeks to determine the
control parameters of a natural system that produce a given set of observed
measurements. Recent work has shown impressive results using deep learning, but
we note that there is a trade-off between model performance and computational
time. For some applications, the computational time at inference for the best
performing inverse modeling method may be overly prohibitive to its use. We
present a new method that leverages multiple manifolds as a mixture of backward
(e.g., inverse) models in a forward-backward model architecture. These multiple
backwards models all share a common forward model, and their training is
mitigated by generating training examples from the forward model. The proposed
method thus has two innovations: 1) the multiple Manifold Mixture Network (MMN)
architecture, and 2) the training procedure involving augmenting backward model
training data using the forward model. We demonstrate the advantages of our
method by comparing to several baselines on four benchmark inverse problems,
and we furthermore provide analysis to motivate its design.Comment: This paper has been accepted to AAAI 2023; this is not the final
versio
Examining the relationship between work-related factors and work-family-related factors on work-family conflict
The current work-family conflict literature is characterized by limitations in focus and methodology, particularly with a failure to link work-family conflict with work-family policies. This study compares the influence of work-related factors and work-family related factors on work-family conflict in two directions. A local government organization in New Zealand was the setting. Findings show that work factors account for a significant component of both work-to-family and family-to-work conflict, although this is far greater on work-family conflict. Work-family practice use had little influence on work-family practices was found to positively associate with family-work conflict. Overall, the finds suggest managers in search of reducing employee conflict should focus directly upon work factors such as workload, rather than see to use work-family practices as the primary way to reduce conflict
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