High Speed Areas Research Articles

New method for the on-line signature verification based on horizontal partitioning

Verification of identity based on the analysis of dynamic signatures is an important problem of biometrics. The effectiveness of the verification significantly increases when the dynamic characteristics of signature (e.g. velocity of the pen) are considered. These characteristics are individual for each user and difficult to imitate. The effectiveness of the verification can be further improved by using partitioning. In this paper we propose a new method which uses partitioning. In our method partitions represent areas of high and low speed of signature and high and low pen׳s pressure. All selected partitions are used by our algorithm, but more important in the classification process are these partitions, in which the signatures of the user acquired during training phase are more stable. Moreover, final classification is interpretable. In this paper we present the simulation results of the proposed method for the two databases: SVC2004 and BioSecure Database.

Modeling of Error Analysis Simulation of Normal Circular Arc Bevel Gear Transmission

The normal circular arc bevel gears are used in industrial areas of high speed, high bearing and high strength widely. A mathematical simulation model is built and it can analyze transmission error and contact zone of normal circular arc bevel gears. In this model, the instantaneous engaging points of gear pair are transformed into the least-values of rotary angles of corresponding points between two gears along the final motion, so this method is very simple and effective. Under the condition of existing helix angle error, transmission error and contact zone of a pair of normal circular arc bevel gears are simulating analyzed. At last, the operation test of contact zone of gears indicates gears transmission is stable and the gears contact zones are largely in line with the simulation results.

Sand erosion technique applied to wind resource assessment

One of the major challenges of the wind energy sector is to accurately predict the wind potential. This task is especially difficult in mountainous terrains where the topography can imply complex relief-induced flows. Wind tunnel testing is one of the possibilities to simulate and predict the wind for wind turbine micro-siting. Most advanced quantitative measurement techniques can be used in the wind tunnel, however, measuring the whole terrain to find the highest wind potential zones is very time-consuming. This paper proposes to use a very simple, quick and cheap technique to detect and evaluate the high wind speed areas over an entire model. Commonly used for pedestrian wind comfort assessment, the sand erosion technique is here applied to wind resource assessment. The technique can provide valuable qualitative information but can also give an order of magnitude of the local speed-up. It is first applied to a backward facing step flow and then on a mountainous terrain. An amplification factor and the fractional speed-up ratio (FSR) can be calculated over the entire mountain. For high speed positions results extracted from sand erosion appears to be comparable the one calculated by particle image velocimetry. The technique is repeatable, able to perform a detection of the high speed area, and capable of giving an estimation of the amplitude of the wind. The technique allows to restrict the use of quantitative measurements to the most interesting areas.

CMOS CIRCUIT DESIGN OF A TAKAGI-SUGENO FUZZY LOGIC CONTROLLER

This paper presents a low power CMOS analog integrated circuit of a Takagi–Sugeno fuzzy logic controller with voltage/voltage interface, small chip area, relatively high accuracy and medium speed, which is composed of several improved functional blocks. Z-shaped, Gaussian and S-shaped membership function circuits with compact structures are designed, performing well with low power, high speed and small areas. A current minimization circuit is provided with high accuracy and high speed. A follower-aggregation defuzzification block composed of several multipliers for center of gravity (COG) defuzzification is presented without using a division circuit. Based on these blocks, a two-input one-output singleton fuzzy controller with nine rules is designed under a CMOS 0.6 μm standard technology provided by CSMC. HSPICE simulation results show that this controller reaches an accuracy of ±3% with power consumption of only 3.5 mW (at ±2.5 V). The speed of this controller goes up to 0.625M Fuzzy Logic Inference per Second (FLIPS), which is fast enough for real-time control.

Habitat preferences and interannual variability in occurrence of the harbour porpoise Phocoena phocoena off northwest Scotland

The harbour porpoise Phocoena phocoena is the most common cetacean around the British Isles, but knowledge of its ecology, habitat preferences and inter-annual variability is still inadequate. Here, sightings collected by the Sea Watch Foundation during vessel surveys in West Scotland (August during the years 1993, 1994, 1996 and 1997) were critically analysed and used to construct a predictive habitat model for harbour porpoises in the Greater Minch. Generalised additive models were used to analyse relative abundance in relation to environmental variables; a preference for waters within 15 km from the shore and between 50 and 150 m depth was clearly identified. A relationship between tidal variables and porpoise distribution was also recognised with more sightings predicted for high tidal stream speed areas as well as during times of high tide. Maps constructed from the model were used to identify potential ‘hotspots’and compare between years. Four areas with high relative abundance were identified in (1) the region between Ardnamurchan, Coll and the Small Isles, (2) southeast of Barra, (3) northeast of Skye to Gairloch, and (4) west of Pairc Peninsula (Isle of Lewis) to Shiant Islands. Number of sightings fluctuated up to 4-fold between consecutive years; such extreme variability in relative abundance is offered as a bench-mark for comparing trends in the future as well as evidence that the Greater Minch represents only a small part of the effective range of this population.

Volumetric breast density evaluation from ultrasound tomography images

Previous ultrasound tomography work conducted by our group showed a direct correlation between measured sound speed and physical density in vitro, and increased in vivo sound speed with increasing mammographic density, a known risk factor for breast cancer. Building on these empirical results, the purpose of this work was to explore a metric to quantify breast density using our ultrasound tomography sound speed images in a manner analogous to computer-assisted mammogram segmentation for breast density analysis. Therefore, volumetric ultrasound percent density (USPD) is determined by segmenting high sound speed areas from each tomogram using a k-means clustering routine, integrating these results over the entire volume of the breast, and dividing by whole-breast volume. First, a breast phantom comprised of fat inclusions embedded in fibroglandular tissue was scanned four times with both our ultrasound tomography clinical prototype (with 4 mm spatial resolution) and CT. The coronal transmission tomograms and CT images were analyzed using semiautomatic segmentation routines, and the integrated areas of the phantom's fat inclusions were compared between the four repeated scans. The average variability for inclusion segmentation was approximately 7% and approximately2%, respectively, and a close correlation was observed in the integrated areas between the two modalities. Next, a cohort of 93 patients was imaged, yielding volumetric coverage of the breast (45-75 sound speed tomograms/patient). The association of USPD with mammographic percent density (MPD) was evaluated using two measures: (1) qualitative, as determined by a radiologist's visual assessment using BI-RADS Criteria and (2) quantitative, via digitization and semiautomatic segmentation of craniocaudal and mediolateral oblique mammograms. A strong positive association between BI-RADS category and USPD was demonstrated [Spearman rho = 0.69 (p < 0.001)], with significant differences between all BI-RADS categories as assessed by one-way ANOVA and Scheffé posthoc analysis. Furthermore, comparing USPD to calculated mammographic density yielded moderate to strong positive associations for CC and MLO views (r2 = 0.75 and 0.59, respectively). These results support the hypothesis that utilizing USPD as an analogue to mammographic breast density is feasible, providing a nonionizing, whole-breast analysis.

TH-E-L100J-07: Comparison of Mammographic Percent Density and Volumetric Percent Density Determined From Ultrasound Tomography Images

Purpose: Previous ultrasound tomography work conducted by our group showed a direct correlation between measured sound speed and physical density in vitro, and increased in vivo sound speed with increasing mammographic density, a known risk factor for breast cancer. Building on these empirical results, we investigated the use of volumetric ultrasound percent density (USPD) for breast density estimation. Method and Materials: A breast phantom comprised of fat inclusions embedded in fibroglandular tissue was scanned four times with both ultrasound tomography and CT. The coronal transmission tomograms and corresponding CT images were analyzed using a semi-automatic segmentation routine. Next, a cohort of ∼100 patients was imaged encompassing the entire breast volume (50–75 tomograms/patient). USPD was determined by segmenting high sound speed areas from each slice using a k-means clustering routine, integrating these results over the entire breast, and dividing by total breast area. USPD was evaluated using two mammographic density measures: (1) qualitative, as determined by a radiologist's visual assessment using BI-RADS Criteria and (2) quantitative, via digitization and semi-automatic segmentation of craniocaudal and medio-lateral oblique mammograms. Results: The integrated areas of the phantom's fat inclusions were compared using both transmission ultrasound and CT for four repeated scans. The average variability for inclusion segmentation was ∼2% and ∼10%, respectively, and a close correlation was observed in the integrated areas between the two modalities. A strong positive association between BI-RADS category and USPD was demonstrated. Furthermore, comparing USPD to calculated mammographic density yielded moderate to strong positive associations (Pearson r = 0.76–0.84) for MLO and CC views, respectively. Conclusion: These results support the hypothesis that utilizing USPD as an analogue to mammographic breast density is feasible. USPD has the potential to provide a non-ionizing, whole-breast analysis of breast density, which may better elucidate the relationship between breast density and breast cancer risk.

Parallel Queue Processor Architecture Based on Produced Order Computation Model

This paper proposes novel produced order parallel queue processor architecture. To store intermediate results, the proposed system uses a first-in-first-out (FIFO) circular queue-registers instead of random access registers. Datum is inserted in the queue-registers in produced order scheme and can be reused. We show that this feature has profound implications in the areas of parallel execution, programs compactness, hardware simplicity and high execution speed. Our performance evaluations show a significant performance improvement (e.g., 10 to 26% decrease in program size and 6 to 46% decrease in execution time over a range of benchmark programs) when compared with the earlier proposed architecture.

Evaluation of temperature and wind over Antarctica in a Regional Atmospheric Climate Model using 1 year of automatic weather station data and upper air observations

The Regional Atmospheric Climate Model version 2 (RACMO2/ANT) is used to simulate the Antarctic atmosphere for the year 1998. The parameterizations of the physical processes in the model are taken from the European Centre for Medium‐Range Weather Forecasts (ECMWF) global model and adapted to better represent the specific conditions over the Antarctic continent. The snow albedo was increased by decreasing the rate of albedo change as a function of temperature. This results in a decrease, and an improvement, in near‐surface air temperatures in summer, especially over the Antarctic plateau. The surface roughness length for momentum was decreased. This increases the wind speed over the total atmospheric column. As a result, wind speeds better correspond to measurements, especially near the surface and in high wind speed areas. Comparison with ECMWF 40‐year reanalyses (ERA40) data show that RACMO2/ANT better reproduces the near‐surface conditions in terms of temperature and wind speed mainly due to the changes made to the physics description. Away from the surface, ERA40 better corresponds to observations due to the inclusion of the observed profiles in the reanalyses.

The hydrodynamics of dolphin drafting

BackgroundDrafting in cetaceans is defined as the transfer of forces between individuals without actual physical contact between them. This behavior has long been surmised to explain how young dolphin calves keep up with their rapidly moving mothers. It has recently been observed that a significant number of calves become permanently separated from their mothers during chases by tuna vessels. A study of the hydrodynamics of drafting, initiated in the hope of understanding the mechanisms causing the separation of mothers and calves during fishing-related activities, is reported here.ResultsQuantitative results are shown for the forces and moments around a pair of unequally sized dolphin-like slender bodies. These include two major effects. First, the so-called Bernoulli suction, which stems from the fact that the local pressure drops in areas of high speed, results in an attractive force between mother and calf. Second is the displacement effect, in which the motion of the mother causes the water in front to move forwards and radially outwards, and water behind the body to move forwards to replace the animal's mass. Thus, the calf can gain a 'free ride' in the forward-moving areas. Utilizing these effects, the neonate can gain up to 90% of the thrust needed to move alongside the mother at speeds of up to 2.4 m/sec. A comparison with observations of eastern spinner dolphins (Stenella longirostris) is presented, showing savings of up to 60% in the thrust that calves require if they are to keep up with their mothers.ConclusionsA theoretical analysis, backed by observations of free-swimming dolphin schools, indicates that hydrodynamic interactions with mothers play an important role in enabling dolphin calves to keep up with rapidly moving adult school members.

An Aircraft Study of Mesoscale Surface Wind Patterns and Associated Meteorological Conditions over Cape St. Francis, South Africa

Abstract Aircraft surveys have been conducted to assess the mesoscale pattern of wind and weather over Cape Saint Francis, South Africa, on the southern tip of the African continent. Ten surveys were flown at a level of 100 m above ground during November 1991, and wind velocity, turbulence, and temperature were monitored. Results were stratified into composites according to the mean direction and speed of the wind. Under the prevailing westerly wind, three areas of high speed were found that may constitute optimal sites for wind energy turbines. These areas of high velocities lie along the tops of low rolling hills in the vicinity of the Krom River at Cape Saint Francis. The usefulness of aircraft surveys in developing an understanding of the mesoscale pattern of winds and associated meteorological fields is emphasized.

The Kamishak Gap wind as depicted in DMSP OLS and SSM/I data

Abstract DMSP visual and infrared Operational Line Scanner (OLS) data reveal several effects of a mountain gap wind generated by wind flow through the Kamishak Gap on the west side of Cook Inlet, Alaska. The existence of the wind can be inferred through one of three separate effects apparent in the data: (1) a roughened sea effect, appearing as a dark grey shade swath within a sunglint pattern; (2) an anomalous grey shade effect induced by sea spray and aerosols, and, (3) a multiple cloud line effect originating as a result of a moisture flux from the sea to the air in a high speed, cold air, coastal outbreak. The Special Sensor Microwave Imager (SSM/I) of the DMSP satellite provides another means to detect the Kamishak Gap wind due to the sensitivity of this sensor to changes in microwave emission of the sea surface as a result of sea spray and foam in high wind speed areas and to associated changes in integrated water vapour content (oceanic total precipitable water). Developed algorithms provide a methodology to quantify from a satellite perspective some of the characterisitics of such events.