Two lignite samples, Beulah No. 3 and Big Brown No. 1, were liquefied at 420 °C using H2 and synthesis gas to determine the optimum beneficial amount of H2S in the batch autoclave reactor. Under the conditions employed, 50–100 psi partial pressure of H2S, nominally 4–10 wt% of daf lignite, was optimum for both samples. Synthesis gas outperformed H2 with and without H2S for the liquefaction of the two coals. 相似文献
Body mass, as well as distribution of body fat, are predictors of both diabetes and cardiovascular disease. In Northern Sweden,
despite a marked increase in average body mass, prevalence of diabetes was stagnant and myocardial infarctions decreased.
A more favourable distribution of body fat is a possible contributing factor. 相似文献
A method for measuring mixing performance in large-scale vessels is investigated. The method is evaluated experimentally in a pilotscale reactor and by using a model based on the three-dimensional calculation of the flow field. The method is based on injection of a tracer and measuring the concentration with several detectors at different locations. The mixing performance is measured as the decay rate of the difference between the concentration at the detectors and the final concentration.
The model predicts a strong dependence on injection point. The assumption of a first-order decay rate of the concentration deviation is more appropriate for some injection points. 相似文献
Repeated administration of highly purified eicosapentaenoic acid (as ethyl ester) resulted in a decrease in plasma triglycerides
and high density lipoprotein (HDL) cholesterol. This was accompanied by a stimulation in the activities of carnitine palmitoyltransferase,
fatty acyl-CoA oxidase and peroxisomal β-oxidation in the liver. The results suggest that the triglyceride-lowering effect
observed with eicosapentaenoic acid may be due to a reduced supply of fatty acids for hepatic triglyceride synthesis because
of increased fatty acid oxidation. Eicosapentaenoic acid feeding marginally affected the triglyceride content of heart and
mitochondrial and peroxisomal enzyme activities. 相似文献
This paper discusses a method for estimating noise covariances from process data. In linear stochastic state-space representations the true noise covariances are generally unknown in practical applications. Using estimated covariances a Kalman filter can be tuned in order to increase the accuracy of the state estimates. There is a linear relationship between covariances and autocovariance. Therefore, the covariance estimation problem can be stated as a least-squares problem, which can be solved as a symmetric semidefinite least-squares problem. This problem is convex and can be solved efficiently by interior-point methods. A numerical algorithm for solving the symmetric is able to handle systems with mutually correlated process noise and measurement noise. 相似文献
Abstract. Even though many of today's vision algorithms are very successful, they lack robustness, since they are typically tailored
to a particular situation. In this paper, we argue that the principles of sensor and model integration can increase the robustness
of today's computer-vision systems substantially. As an example, multi-cue tracking of faces is discussed. The approach is
based on the principles of self-organization of the integration mechanism and self-adaptation of the cue models during tracking.
Experiments show that the robustness of simple models is leveraged significantly by sensor and model integration. 相似文献
This paper describes a new approach to mobile robot position estimation, based on principal component analysis of laser range data. An eigenspace is constructed from the principal components of a large number of range data sets. The structure of an environment, as seen by a range sensor, is represented as a family of surfaces in this space. Subsequent range data sets from the environment project as a point in this space. Associating this point to the family of surfaces gives a set of candidate positions and orientations (poses) for the sensor. These candidate poses correspond to positions and orientations in the environment which have similar range profiles. A Kalman filter can be used to select the most likely candidate pose based on coherence with small movements.
The first part of this paper describes how a relatively small number of depth profiles of an environment can be used to generate a complete eigenspace. This space is used to build a representation of the range scan profiles obtained from a regular grid of positions and orientations (poses). This representation has the form of a family of surface (a manifold). This representation converts the problem of associating a range profile to possible positions and orientations into a table lookup. As a side benefit, the method provides a simple means to detect obstacles in a range profile. The final section of the paper reviews the use of estimation theory to determine the correct pose hypothesis by tracking. 相似文献