41 research outputs found
Effects of timing of corn silage supplementation on digestion, fermentation pattern, and nutrient flow during continuous culture fermentation of a short and intensive orchardgrass meal
No full textFeeding alfalfa-grass or red clover–grass mixture baleage: Effect on milk yield and composition, ruminal fermentation and microbiota taxa relative abundance, and nutrient utilization in dairy cows
No full textABSTRACT: Our goal was to investigate the effect of diets containing baleages harvested from alfalfa-grass or red clover–grass mixture on production performance, ruminal fermentation and microbiota taxa relative abundance, milk fatty acid profile, and nutrient utilization in dairy cows. Twenty Jersey cows (18 multiparous and 2 primiparous) averaging (mean ± SD) 148 ± 45.2 days in milk and 483 ± 65.4 kg of body weight in the beginning of the study were used in a randomized complete block design with repeated measures over time. The experiment lasted 9 wk, with a 2 wk covariate period followed by 7 wk of data and sample collection (wk 4 and 7 used in the statistical analyses). Cows were fed diets containing (dry matter basis) 35% of a concentrate mash and the following forage sources: (1) 65% second- and third-cut (32.5% each) alfalfa-grass mixture baleages (ALF) or (2) 65% second- and third-cut (32.5% each) red clover–grass mixture baleages (RC). Diets did not affect dry matter intake, milk yield, and concentrations of milk fat and true protein. In contrast, milk fat yield tended to decrease and energy-corrected milk yield decreased with feeding RC versus ALF. The apparent total-tract digestibilities of dry matter, organic matter, and ash-free neutral detergent fiber, milk proportions of trans-10 18:1, cis-9,cis-12,cis-15 18:3, and total n-3 fatty acids, ruminal molar proportion of acetate, and plasma concentrations of Leu, Phe, and Val all increased in RC versus ALF. Diet × week interactions were found for several parameters, most notably ruminal molar proportions of propionate and butyrate, ruminal NH3-N, milk urea N, plasma urea N, and plasma His concentrations, urinary N excretion, enteric CH4 production, and all energy efficiency variables. Specifically, ruminal NH3-N and plasma urea N concentrations, urinary excretion of N, and CH4 production decreased in cows fed RC in wk 4 but not in wk 7. Milk urea N concentration decreased and that of plasma His increased with feeding RC during wk 4 and 7, although the magnitude of treatments difference varied between the sampling periods. Efficiency of energy utilization calculated as milk energy/metabolizable energy decreased and that of tissue energy/ME increased in RC versus ALF cows in wk 4, suggesting that ME was portioned toward tissue and not milk in the RC diet. Interactions were also observed for the relative abundance of the rumen bacterial phyla Verrucomicrobiota and Fibrobacterota, with cows offered RC showing greater values than those receiving ALF in wk 4 but no differences in wk 7. Several diet × week interactions were detected in the present study implying short-term treatment responses and warranting further investigations
MeTeaM-A method for characterizing mature software metrics teams
No full textBackground: Metrics teams play an increasingly important role in handling data and information in modern software development organizations; they manage their companies' measurement programs, collect and process data, and develop and distribute information products. Metrics teams can comprise several roles, and their set-up can differ between companies, as can the metrics maturity of host organizations. These differences impact the effectiveness and quality of a team's measurement program. Objective: Our objective was to design and evaluate a model to describe the characteristics of a mature metrics team, which efficiently designs, develops, maintains, and evolves its organization's measurement program. Method: We conducted an action research study on four metrics teams of four distinct companies. We designed and evaluated a domain-specific model for assessing the maturity of metrics teams - MeTeaM - and also assessed the four metrics teams per se. Results: Our results were two-fold: the creation of the metrics team maturity model MeTeaM and a template to assess metrics teams. Our evaluation showed that the model captures the characteristics of successful metrics teams and quantifies the maturity status of both the metrics teams and their host organizations. Conclusions: More mature metrics teams score higher in the MeTeaM model than less mature teams. The assessment provides less mature metrics teams with valuable insights on what factors to improve. Such insights can be shared with and acted upon successfully with their organizations. (C) 2021 The Author(s). Published by Elsevier Inc
Production performance and milk fatty acid profile in grazing dairy cows offered ground corn or liquid molasses as the sole supplemental nonstructural carbohydrate source
No full textThe physics of H-Darrieus turbine starting behavior
No full textThis paper provides a resolution to the contradictory accounts of whether or not the Darrieus turbine can self-start. The paper builds on previous work proposing an analogy between the aerofoil in Darrieus motion and flapping-wing flow mechanisms. This analogy suggests that unsteadiness could be exploited to generate additional thrust and that this unsteady thrust generation is governed by rotor geometry. Rotors which do not exploit this unsteadiness will not self-start.
To confirm the hypothesis, unsteady effects were measured and then incorporated into a time-stepping rotor analysis and compared to experimental data for self starting wind turbines. When unsteady effects were included the model was able to predict the correct starting behaviour.
The fundamental physics of starting were also studied and parameters that govern the generation of unsteady thrust were explored: namely chord-to-diameter and blade aspect ratios. Further simulation showed that the Darrieus rotor is prone to be locked in a deadband where the thrust is not continuous around a blade rotation. This discrete thrust is caused by the large variation of incidence angle during start-up making the Darrieus blade ineffective during part of the rotation.
The results show that unsteady thrust can be promoted through an appropriate selection of blade aspect and chord-to-diameter ratios, therefore self-starting rotors may be designed. A new definition of self-starting is also proposed
Small U.S. Dairy Farms: Can They Compete?
No full textThe U.S. dairy industry is undergoing rapid structural change, evolving from a structure including many small farmers in the Upper Midwest and Northeast to one that includes very large farms in new production regions. Small farms are struggling to retain competitiveness via improved management and low-input systems. Using data from USDA’s Agricultural Resource Management Survey, we determine the extent of U.S. conventional and pasture-based milk production during 2003-2007, and estimate net returns, scale efficiency, and technical efficiency associated with the systems across different operation sizes. We compare the financial performance of small conventional and pasture-based producers with one another and with largescale producers. A stochastic production frontier is used to analyze performance over the period for conventional and pasture technologies identified using a binomial logit model. Large conventional farms generally outperformed smaller farms using most economic measures – technical efficiency, various profitability measures, and returns to scale.Pasture-based system, technical efficiency, returns to scale, dairy, Livestock Production/Industries, Productivity Analysis,
Framework to Evaluate Power Portfolio Dispatch Considering Balancing Market Participation
No full textThe power grid is rapidly experiencing a transformation driven by renewable and climate targets which pose a huge challenge to maintain the system stability and reliability, thus balancing services become more crucial now than ever. To provide balancing services in a cost-efficient way, it is necessary to develop predictive models which can optimize power portfolio in an online manner. This paper presents the development of an Online Predictive Dispatch Optimizer and its connection with a grid model that simulates power and frequency control within interconnected power systems. The performance of the dispatch optimizer and its connection with the grid model is tested by simulating several cases where the adequacy of the model is confirmed, especially regarding its ability to manage energy imbalance in real-time. The outcomes and flexibility of this framework can be used to quantitatively evaluate the operation of power portfolio owners in the power grid.Intelligent Electrical Power Grid
Dairy Resource Management: A Comparison of Conventional and Pasture-Based Systems
No full textFacing rapid and significant change in the sector, U.S. dairy production trends from 1993-2005 were tracked and performance measures (scale and technical efficiency and returns on assets) were estimated for conventional and pasture-based dairy farms using data from USDA's Agricultural Resource Management Survey. Comparisons of relative economic performance of dairy farms by size and type are made.dairy operations, pasture-based systems, technical efficiency, Livestock Production/Industries,
