9,840 research outputs found
Adaptive thresholding in dynamic scene analysis for extraction of fine line
This paper presents an adaptive threshold method whereby a fine thin line of one-pixel width lines could be detected in a gray level images. The proposed method uses the percentage difference between the mean of the pixels within a window and the center pixel. The minimum threshold value however is heuristically set to 32. If the percentage difference is greater than 40% then the threshold value will be set to the difference value. This method has been applied in detecting moving objects with fine lines and the results showed that the method was able to pickup straight thin edges that belong to the moving objec
Improving International Comparisons of Real Output: The ICP 2005 Benchmark and its Implications for China
The latest round of the International Comparisons Program (ICP 2005) compares the purchasing power of currencies and real output of 146 countries. Using price quote data from nine countries in the Asia-Pacific region, we consider ways of improving the methods used in ICP 2005 and new applications of these methods (e.g., for calculating rural-urban price differentials). The most striking result in ICP 2005 was that China came out 40 percent smaller than previously thought. We also evaluate the extent to which this finding can be attributed to excessive sampling of prices in China from urban areas or of unrepresentative products.International Comparisons Program; Country-Product-Dummy Method; Price Index; Basic Heading; Urban-Rural Price Differences; Representative and Unrepresentative Products; Asia-Pacific Region
A Cross-National Comparison of Consumers\u27 Attitudes Toward Direct Marketing and Purchase Intention
Existing research indicates that attitudes toward the three elements of direct marketing (the source, mode, and response channel) influence consumers\u27 intentions to purchase directly marketed products. While research investigating attitudes and consumers\u27 response has been conducted in the U.S., there has been no research to date which examines attitude structures and purchase intentions towards direct marketing in a multi-country setting, in spite of the standardized global efforts of direct marketeers. This study presents findings on attitude structures regarding direct marketing for three affluent open markets, the U.S., Singapore, and the Netherlands and empirically investigates the relationships between these consumers\u27 attitudes toward the three elements of direct marketing and purchase intentions
Flexible Spatial and Temporal Hedonic Price Indexes for Housing in the Presence of Missing Data
We propose a flexible hedonic methodology for computing house price indexes that uses multiple imputation (MI) to account for missing data (a huge problem in housing data sets). Ours is the first study to use MI in this context. We also allow for spatial correlation, include interaction terms between characteristics, between regions and periods, and between regions and characteristics, and break the regressions up into overlapping blocks of five consecutive periods (quarters in our case). These features ensure that the shadow prices are flexible both across regions and time. This flexible structure makes the derivation of price indexes from the estimated regression equations far from straightforward. We develop innovative methods for resolving this problem and for splicing the overlapping blocks together to generate the overall panel results. We then use our methodology to construct temporal and spatial price indexes for 15 regions in Sydney, Australia on a quarterly basis from 2001 to 2006 and combine them to obtain an overall price index for Sydney. Our hedonic indexes differ quite significantly from the official index for Sydney published by the Australian Bureau of Statistics. We also find clear evidence of convergence in prices across regions from 2001-3 (while prices were rising), and divergence thereafter. We conclude by exploring some of the implications of these empirical findings.Real estate; House prices; Hedonic price index; Missing data; Multiple imputation; Spatial correlation
Electron Scattering in AlGaN/GaN Structures
We present data on mobility lifetime, , quantum lifetime, ,
and cyclotron resonance lifetime, , of a sequence of high-mobility
two-dimensional electron gases in the AlGaN/GaN system, covering a density
range of cm. We observe a large discrepancy
between and (/6) and explain it as
the result of density fluctuations of only a few percent. Therefore, only
--and not -- is a reliable measure of the time between
electron scattering events in these specimens. The ratio
increases with increasing density in this series of samples, but scattering
over this density range remains predominantly in the large-angle scattering
regime
The phasor-FLIM fingerprints reveal shifts from OXPHOS to enhanced glycolysis in Huntington Disease.
Huntington disease (HD) is an autosomal neurodegenerative disorder caused by the expansion of Polyglutamine (polyQ) in exon 1 of the Huntingtin protein. Glutamine repeats below 36 are considered normal while repeats above 40 lead to HD. Impairment in energy metabolism is a common trend in Huntington pathogenesis; however, this effect is not fully understood. Here, we used the phasor approach and Fluorescence Lifetime Imaging Microscopy (FLIM) to measure changes between free and bound fractions of NADH as a indirect measure of metabolic alteration in living cells. Using Phasor-FLIM, pixel maps of metabolic alteration in HEK293 cell lines and in transgenic Drosophila expressing expanded and unexpanded polyQ HTT exon1 in the eye disc were developed. We found a significant shift towards increased free NADH, indicating an increased glycolytic state for cells and tissues expressing the expanded polyQ compared to unexpanded control. In the nucleus, a further lifetime shift occurs towards higher free NADH suggesting a possible synergism between metabolic dysfunction and transcriptional regulation. Our results indicate that metabolic dysfunction in HD shifts to increased glycolysis leading to oxidative stress and cell death. This powerful label free method can be used to screen native HD tissue samples and for potential drug screening
Raw-data attacks in quantum cryptography with partial tomography
We consider a variant of the BB84 protocol for quantum cryptography, the
prototype of tomographically incomplete protocols, where the key is generated
by one-way communication rather than the usual two-way communication. Our
analysis, backed by numerical evidence, establishes thresholds for
eavesdropping attacks on the raw data and on the generated key at quantum bit
error rates of 10% and 6.15%, respectively. Both thresholds are lower than the
threshold for unconditional security in the standard BB84 protocol.Comment: 11 pages, 2 figure
Fireside corrosion degradation of ferritic alloys at 600°C in oxy-fired conditions
This paper reports the results of a study carried out to investigate the effects of simulated coal/biomass combustion conditions on the fireside corrosion. The 1000 h deposit recoat exposure (5 × 200 h cycles) was carried out at 600 °C. In these tests ferritic alloys were used 15Mo3, T22, T23 and T91. Kinetics data were generated for the alloys exposed using both traditional weight change methods and metal loss measurements. The highest rate of corrosion based on EDX results occurred under D1 deposit where provoke mainly by the formation of alkali iron tri-sulphate phase
A hydrodynamic study of a fast‐bed dual circulating fluidized bed for chemical looping combustion
This study explores the use of a dual interconnected circulating fluidized bed (CFB) for chemical looping combustion. This design can enhance gas–solid interactions, but it is difficult to control the solid transfer and circulation rates. With the use of a 1:1 scale cold-flow model, an investigation determining the hydrodynamic behavior of the dual CFB system has been conducted. The cold-flow system consists of two identical fast-bed risers, each with an internal diameter of 100 mm and a height of 7 m. The simplified cold-flow model is based on the chemical looping Pilot-Scale Advanced CO2 Capture Technology (PACT) facility at Cranfield. Here, we have determined the minimum fluidization and transport velocities, and we have assessed the solid density profiles, transport capacity, and potential for the dilution by air/N2 leakage into the CO2 stream exiting the fuel reactor. The experimental procedure uses two different bed materials, molochite (ceramic clay) and FE100 (iron particles), and it satisfies the dynamic scaling laws to model the bed inventory within the system. The results indicate that the two fast-bed risers share similar density and pressure profiles. Stable circulation can be achieved through pneumatic transport. The circulation rate of the system is flexible and can be adjusted by altering the fluidization velocity in the riser and by altering the bed inventory. The gas leakage from the loop seal to the cyclone was found to be sensitive to the bed height and fluidization velocity in the loop seal. However, by maintaining a loop-seal bed height above 600 mm during operation, the outlet stream remains undiluted
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