Interactive grid generation for turbomachinery flow field simulations

The control point form of algebraic grid generation presented provides the means that are needed to generate well structured grids for turbomachinery flow simulations. It uses a sparse collection of control points distributed over the flow domain. The shape and position of coordinate curves can be adjusted from these control points while the grid conforms precisely to all boundaries. An interactive program called TURBO, which uses the control point form, is being developed. Basic features of the code are discussed and sample grids are presented. A finite volume LU implicit scheme is used to simulate flow in a turbine cascade on the grid generated by the program

Dynamics of local grid manipulations for internal flow problems

The control point method of algebraic grid generation is briefly reviewed. The review proceeds from the general statement of the method in 2-D unencumbered by detailed mathematical formulation. The method is supported by an introspective discussion which provides the basis for confidence in the approach. The more complex 3-D formulation is then presented as a natural generalization. Application of the method is carried out through 2-D examples which demonstrate the technique

Long lasting instabilities in granular mixtures

We have performed experiments of axial segregation in the Oyama's drum. We have tested binary granular mixtures during very long times. The segregation patterns have been captured by a CCD camera and spatio-temporal graphs are created. We report the occurence of instabilities which can last several hours. We stress that those instabilities originate from the competition between axial and radial segregations. We put into evidence the occurence of giant fluctuations in the fraction of grain species along the surface during the unstable periods.Comment: 10 pages, 10 figures, (2002

An extension to the theory of steady selective withdrawal for a two layer fluid

Most reservoirs contain stratified fluid and selective withdrawal is used to obtain water of the desired properties. Initially we review the case with an infinite upper layer with a sharp interface. When the total discharge is specified, then the ratio of the discharge from each layer is determined by the criteria of smoothness at the virtual control (i.e. the critical point). At this point, the long wave velocity on the interface is zero. For the case when the upper layer depth is large, we show that the control is in the valve and the virtual control (which determines the ratio of the discharge in each layer) moves further from the source as the total discharge increases. When there is a finite upper layer, a portion of the flow is in the duct and a portion of the flow is in the free surface. We derive the criteria for the virtual control in the free surface flow and show that the duct control occurs first. If we then assume that the flow is not over-specified, we determine the necessary conditions for a smooth transition between the duct and the free surface flow. This enables us to determine the minimum ratio of the upper layer depth to the lower layer depth for the steady duct solution to be valid. This contrasts with the conclusions of Bryant and Wood (1976)

NASA Workshop on future directions in surface modeling and grid generation

Given here is a summary of the paper sessions and panel discussions of the NASA Workshop on Future Directions in Surface Modeling and Grid Generation held a NASA Ames Research Center, Moffett Field, California, December 5-7, 1989. The purpose was to assess U.S. capabilities in surface modeling and grid generation and take steps to improve the focus and pace of these disciplines within NASA. The organization of the workshop centered around overviews from NASA centers and expert presentations from U.S. corporations and universities. Small discussion groups were held and summarized by group leaders. Brief overviews and a panel discussion by representatives from the DoD were held, and a NASA-only session concluded the meeting. In the NASA Program Planning Session summary there are five recommended steps for NASA to take to improve the development and application of surface modeling and grid generation

Information Aggregation in Arrow-Debreu Markets: An Experiment

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.Studies of experimental and betting markets have shown that markets are able to efficiently aggregate information dispersed over many traders. We study information aggregation in Arrow-Debreu markets using a novel information structure. Compared to previous studies, the information structure is more complex, allows for heterogeneity in information among traders – which provides insights into the way in which information is gradually disseminated in the market – and generates situations in which all traders hold identical beliefs over the traded assets’ values, thus providing a harsh stress test for belief updating. We find little evidence for information aggregation and dissemination in early rounds. Nonetheless, after traders gain experience with the market mechanism and structure, prices converge to reveal the true state of the world. Elicited post-market beliefs reveal that markets are able to efficiently aggregate dispersed information even if individual traders remain uninformed, consistent with the marginal trader hypothesis

Characterization of an Improved, Real-Time MEMS-Based Phase-Shifting Interferometer

We describe and present detailed performance characterizations for an enhanced version of our MEMS-Based Phase-Shifting Interferometer (MBPSI) that achieves 13 times denser motion reconstruction than our original system. We measure the noise level to be ≤±6 nm λ for a 660 nm laser), and the frequency-resolution to be ≤ 0.03Hz for 31Hz motion captured at 300Hz. We have successfully tracked a piezo-based actuator, driven with an arbitrary waveform composed of transients ≤10Hz

Habitat Influences Arthropod Biodiversity

Biodiversity is an important indicator of environmental health. Insects are very interconnected ecologically, very adaptable, and highly diverse, making them excellent indicators for environmental health. Human interference tends to disrupt ecosystems to make them less diverse (Benton et al. 2003). A greater variety of plants should be expected to support a greater variety of insects, aiding environmental health (e.g., Diniz et al. 2010). We tested the effect of degree of habitat disturbance/plant diversity on insect diversity in 6 habitats over three dates, expecting to see greater insect diversity where there is greater plant diversity. We calculated insect biodiversity using Simpson’s Index of Diversity, and found greater insect abundance and diversity in more diverse habitats. Insect diversity is important for habitat health, so as insect diversity declines, other animals in those ecosystems suffer as well, as the food web is disrupted (Kemp and Ellis 2017)

A two-layer dimension reduction and two-tier classification model for anomaly-based intrusion detection in IoT backbone networks

With increasing reliance on Internet of Things (IoT) devices and services, the capability to detect intrusions and malicious activities within IoT networks is critical for resilience of the network infrastructure. In this paper, we present a novel model for intrusion detection based on two-layer dimension reduction and two-tier classification module, designed to detect malicious activities such as User to Root (U2R) and Remote to Local (R2L) attacks. The proposed model is using component analysis and linear discriminate analysis of dimension reduction module to spate the high dimensional dataset to a lower one with lesser features. We then apply a two-tier classification module utilizing Naïve Bayes and Certainty Factor version of K-Nearest Neighbor to identify suspicious behaviors. The experiment results using NSL-KDD dataset shows that our model outperforms previous models designed to detect U2R and R2L attacks