Future of substation monitoring: It is not just the software

The future of online monitoring of HV substation equipment is closely linked to Enterprise Asset Management systems provided that proper measures are implemented for the EAM system to deliver the expected results. Those measures include trained personnel, detailed knowledge of one’s assets, technically and economically feasible maintenance process, flow of information to personnel, and collaboration with a company that can provide the monitoring system as well as the expertise in its implementation. Monitoring and diagnostics is now part of the business process which contributes to reduction in forced outages, and a more secure and reliable system

SHOPPING FOR MEAT: EMPIRICAL DEMAND ESTIMATION FOR NATURAL BEEF ACROSS STORE CHOICES

Conventional supermarkets concentrate on capturing the largest pool of consumers to generate profits from the industry's low margins. Selling to the largest pool of customers means that marketing, promotion, stocking and service decisions are based on the tastes and preferences of an average consumer. Innovators in the grocery industry, recognizing a shift in consumer tastes and preferences, are changing the industry to attract smaller segments of consumers. The theory presented here demonstrates a method to understand the value of product diversification and a model of the gains from providing products that may not have broad appeal to the average customer base. The increase in retail returns through this approach of developing in-store niches lies not in increased single-item purchases of any one consumer, but through the increased number of items purchased (a larger bundle) by an individual on a single shopping trip.Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

Characteristics of market for natural beef in Colorado and northern New Mexico

March 2002Includes bibliographical references.The objective of this study is to identify those consumers with the highest willingness to pay and identify which properties of ‘natural meats’ are most important to these consumers. Findings show that consumers are willing to pay a higher percentage premium for natural ground beef than for natural beefsteak. We also categorize respondents using the estimated likelihood of paying a premium for natural beef to compare and contrast how several variables differ among potential customers Several demographics (age and income), as well as shopping behavior and types of meat purchased, are significantly associated with those willing to buy at a premium

Energy recovery in individuals with knee osteoarthritis.

OBJECTIVE: Pathological gaits have been shown to limit transfer between potential (PE) and kinetic (KE) energy during walking, which can increase locomotor costs. The purpose of this study was to examine whether energy exchange would be limited in people with knee osteoarthritis (OA). METHODS: Ground reaction forces during walking were collected from 93 subjects with symptomatic knee OA (self-selected and fast speeds) and 13 healthy controls (self-selected speed) and used to calculate their center of mass (COM) movements, PE and KE relationships, and energy recovery during a stride. Correlations and linear regressions examined the impact of energy fluctuation phase and amplitude, walking velocity, body mass, self-reported pain, and radiographic severity on recovery. Paired t-tests were run to compare energy recovery between cohorts. RESULTS: Symptomatic knee OA subjects displayed lower energetic recovery during self-selected walking speeds than healthy controls (P = 0.0018). PE and KE phase relationships explained the majority (66%) of variance in recovery. Recovery had a complex relationship with velocity and its change across speeds was significantly influenced by the self-selected walking speed of each subject. Neither radiographic OA scores nor subject self-reported measures demonstrated any relationship with energy recovery. CONCLUSIONS: Knee OA reduces effective exchange of PE and KE, potentially increasing the muscular work required to control movements of the COM. Gait retraining may return subjects to more normal patterns of energy exchange and allow them to reduce fatigue

Entry of double-stranded deoxyribonucleic acid during transformation of Neisseria gonorrhoeae.

The state of donor deoxyribonucleic acid after entry into competent cells was examined by assaying the transformed cell lysates for donor-marker transforming activity and density of donor deoxyribonucleic acid in CsCl gradients. The experiments showed that deoxyribonucleic acid entered in native, double-stranded form

Structural Health Monitoring of Precast Concrete Box Girders Using Selected Vibration-Based Damage Detection Methods

Precast, prestressed concrete box girders are commonly used as superstructure components for short and medium span bridges. Their configuration and typical side-by-side placement make large portions of these elements inaccessible for visual inspection or the application of nondestructive testing techniques. This paper demonstrates that vibration-based damage detection (VBDD) is an effective alternative for monitoring their structural health. A box girder removed from a dismantled bridge was used to evaluate the ability of five different VBDD algorithms to detect and localize low levels of spalling damage, with a focus on using a small number of sensors and only the fundamental mode of vibration. All methods were capable of detecting and localizing damage to a region within approximately 1.6 times the longitudinal spacing between as few as six uniformly distributed accelerometers. Strain gauges configured to measure curvature were also effective, but tended to be susceptible to large errors in near support damage cases. Finite element analyses demonstrated that increasing the number of sensor locations leads to a proportional increase in localization accuracy, while the use of additional modes provides little advantage and can sometimes lead to a deterioration in the performance of the VBDD techniques

Application of Discrete Differential Forms to Spherically Symmetric Systems in General Relativity

In this article we describe applications of Discrete Differential Forms in computational GR. In particular we consider the initial value problem in vacuum space-times that are spherically symmetric. The motivation to investigate this method is mainly its manifest coordinate independence. Three numerical schemes are introduced, the results of which are compared with the corresponding analytic solutions. The error of two schemes converges quadratically to zero. For one scheme the errors depend strongly on the initial data.Comment: 22 pages, 6 figures, accepted by Class. Quant. Gra

Determination of perchlorate in infant formula by isotope dilution ion chromatography/tandem mass spectrometry

A sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in infant formula. The perchlorate was extracted from infant formula by using 20 ml of methanol and 5 ml of 1% acetic acid. All samples were spiked with 18O4 isotope-labelled perchlorate internal standard prior to extraction. After purification on a graphitised carbon solid-phase extraction column, the extracts were injected into an ion chromatography system equipped with an Ionpac AS20 column for separation of perchlorate from other anions. The presence of perchlorate in samples was quantified by isotope dilution mass spectrometry. Analysis of both perchlorate and its isotope-labelled internal standard was carried out on a Waters Quattro Ultima triple quadrupole mass spectrometer operating in a multiple reaction monitoring (MRM) negative ionisation mode. The method was validated for linearity and range, accuracy, precision, sensitivity, and matrix effects. The limit of quantification (LOQ) was 0.4 μg 1−1 for liquid infant formula and 0.95 μg kg−1 for powdered infant formula. The recovery ranged from 94% to 110% with an average of 98%. This method was used to analyse 39 infant formula, and perchlorate concentrations ranging from <LOQ to 13.5 μg 1−1

Twistor geometry of a pair of second order ODEs

We discuss the twistor correspondence between path geometries in three dimensions with vanishing Wilczynski invariants and anti-self-dual conformal structures of signature $(2, 2)$. We show how to reconstruct a system of ODEs with vanishing invariants for a given conformal structure, highlighting the Ricci-flat case in particular. Using this framework, we give a new derivation of the Wilczynski invariants for a system of ODEs whose solution space is endowed with a conformal structure. We explain how to reconstruct the conformal structure directly from the integral curves, and present new examples of systems of ODEs with point symmetry algebra of dimension four and greater which give rise to anti--self--dual structures with conformal symmetry algebra of the same dimension. Some of these examples are $(2, 2)$ analogues of plane wave space--times in General Relativity. Finally we discuss a variational principle for twistor curves arising from the Finsler structures with scalar flag curvature.Comment: Final version to appear in the Communications in Mathematical Physics. The procedure of recovering a system of torsion-fee ODEs from the heavenly equation has been clarified. The proof of Prop 7.1 has been expanded. Dedicated to Mike Eastwood on the occasion of his 60th birthda