1,438 research outputs found
BBPR versie 8: Uw bedrijf doorgelicht
BBPR maakt ook begrotingen van technische resultaten bij veranderingen in de bedrijfsvoering
Het schapenstapelmodel
Dit model berekent per jaar de opname aan ruwvoer en krachtvoer van een koppel schapen alsmede het aantal afgevoerde schapen en lammeren met de bijbehorende afvoergewichten
Nonlinear modeling of thermoacoustic systems
Thermoacoustic systems convert energy from heat to acoustic power and vice versa. These systems have commercial interest due to the high potential efficiency and low number of moving parts. To numerically predict the performance of a thermoacoustic device inherent nonlinearities in the system, such as thermoacoustic streaming and generation of harmonics need to be taken into account. We present a nonlinear frequency domain method with which these nonlinearities in thermoacoustic systems are modeled in a computationally efficient manner. Using this method, the nonlinear periodic steady state of a thermoacoustic engine can directly be computed, without computing the long initial transient of the system. In this publication, the developed method is applied to compute the periodic steady state of an experimental standing wave engine. The results obtained match well with experimental data
Rekenprogramma's voor adviseur en veehouder
Wageningen UR Livestock Research heeft rekenprogramma’s voor melkvee (Bedrijfs Begrotingsprogramma Rundvee -BBPR), pluimvee (Bedrijfswijzer Pluimvee) en varkens (Bedrijfswijzer Varkens). Deze programma’s simuleren de bedrijfsvoering van een praktijkbedrijf. Wat je daarmee als adviseur en veehouder kunt, beschrijft dit artike
Ruptured abdominal aortic aneurysms: Factors influencing postoperative mortality and long-term survival
Objective:To update mortality rates and long-term survival of patients admitted to the hospital with ruptured abdominal aortic aneurysm (AAA) and to study prognostic factors associated with mortality.Design:Retrospective follow-up.Materials:309 patients (274 men, 35 women, average age 71) admitted to the hospital between January 1980 and January 1994 who were surgically treated for ruptured AAA were studied.Methods:To identify the preoperative (9), intraoperative (23) and postoperative (49) variables associated with mortality logistic regression analysis (mortality within 48 h) and Cox regression analysis (mortality between 48 h and 30 days) were performed.Results:Hospital mortality improved from 1980 to 1994. Compared with the normal population adjusted for age and sex the long-term mortality rate was increased (standardised mortality ratio 2.1; 95% confidence interval 1.7–2.5). Increased age, peroperative hypotension and need for a bifurcated graft were associated with significantly increased mortality. Co-morbidity was not a predictive variable. Overall hospital mortality was 25%.Conclusion:Surgical repair of ruptured AAA should be considered even in patients with co-morbidity. Elderly patients with severe preoperative hypotension have a very high mortality rate and surgery may not be justified in these cases. Long-term survival is also worse in older patients
Error-enhanced augmented proprioceptive feedback in stroke rehabilitation training:a pilot study
Augmented feedback plays an essential role in stroke rehabilitation therapy. When a force is applied to the arm, an augmented sensory (proprioceptive) cue is provided. The question was to find out if stroke patients can learn reach-and retrieval movements with error-enhanced augmented sensory feedback. The movements were performed over a predefined path, and when deviating of the path a force is provided, as colliding to a wall of a tunnel. Two chronic stroke survivors (FM of 53 and 49) performed reach and retrieval movements in a virtual tunnel. When two consecutive series of 15 repetitions of the same movements were performed, there was a consistent decrease of collisions to the wall in the second series of movements. This indicates that these patients were able to learn the predefined trajectory by means of augmented proprioceptive feedback. Despite the small number of patients tested, this finding is promising for the usage of error-enhanced augmented proprioceptive feedback in rehabilitation therapy
Nieuwe versie Normen Voor de Voedervoorziening sluit beter aan op de praktijk
Bij de ontwikkeling van deze nieuwe versie is ook getracht het programma beter aan te laten sluiten op praktijksituaties. In dit artikel worden enkele belangrijke verschillen met de oude versie toegelicht
Membranes for Topological M-Theory
We formulate a theory of topological membranes on manifolds with G_2
holonomy. The BRST charges of the theories are the superspace Killing vectors
(the generators of global supersymmetry) on the background with reduced
holonomy G_2. In the absence of spinning formulations of supermembranes, the
starting point is an N=2 target space supersymmetric membrane in seven
euclidean dimensions. The reduction of the holonomy group implies a twisting of
the rotations in the tangent bundle of the branes with ``R-symmetry'' rotations
in the normal bundle, in contrast to the ordinary spinning formulation of
topological strings, where twisting is performed with internal U(1) currents of
the N=(2,2) superconformal algebra. The double dimensional reduction on a
circle of the topological membrane gives the strings of the topological A-model
(a by-product of this reduction is a Green-Schwarz formulation of topological
strings). We conclude that the action is BRST-exact modulo topological terms
and fermionic equations of motion. We discuss the role of topological membranes
in topological M-theory and the relation of our work to recent work by Hitchin
and by Dijkgraaf et al.Comment: 22 pp, plain tex. v2: refs. adde
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