Classification-oriented structure learning in Bayesian networks for multimodal event detection in videos

We investigate the use of structure learning in Bayesian networks for a complex multimodal task of action detection in soccer videos. We illustrate that classical score-oriented structure learning algorithms, such as the K2 one whose usefulness has been demonstrated on simple tasks, fail in providing a good network structure for classification tasks where many correlated observed variables are necessary to make a decision. We then compare several structure learning objective functions, which aim at finding out the structure that yields the best classification results, extending existing solutions in the literature. Experimental results on a comprehensive data set of 7 videos show that a discriminative objective function based on conditional likelihood yields the best results, while augmented approaches offer a good compromise between learning speed and classification accuracy.     

Microstructural evolution,dislocation density and tensile properties of Al-6.5Si-2.1Cu-0.35Mg alloy produced by different casting processes

Al-Si-Cu-Mg foundry alloys are used in casting process technologies.However,their strength proper-ties remain low due to their microstructural characteristics and porosity.In this work,the microstruc-tural characteristics,dislocation densities,and mechanical properties of Al-Si-Cu-Mg cast alloys prepared through different casting methods were studied experimentally.Four casting processes,namely,gravity casting (GC),rheocasting (RC),thixoforming (Thixo),and Thixo with heat treatment,were used.The GC and RC samples had mainly dendritic α-Al phase microstructures and exhibited coarse Si particles and intermetallic compounds in their interdendritic regions.By contrast,the Thixo and heat-treated Thixo(HT-Thixo) samples exhibited microstructural refinement with uniformly distributed α-Al globules,fine fibrous Si particles,and fragmented intermetallic compounds among α-Al globules.The accumulation of dislocation densities increased in the Thixo sample as the strain was increased due to plastic deforma-tion.Furthermore,the ultimate tensile strength and yield strength of the HT-Thixo sample increased by 87％ and 63％,respectively,relative to those of the GC sample.The cleavage fracture displayed by the GC and RC samples led to brittle failure.Meanwhile,the Thixo and HT-Thixo samples presented dimple-based ductile fracture.     

The Effect of Applied Voltage and Operating Pressure on Emitted X-Ray from Nitrogen (N<Subscript>2</Subscript>) Gas in APF Plasma Focus Device

In the present work, the effect of applied voltage and operating pressure on behaviour of X-rays emitted from nitrogen gas (N₂) used in APF plasma focus facility is investigated. It was found that the optimum conditions for high emissions of SXR and HXR from the plasma focus (PF) are different. At four applied voltages of 10, 11, 12, and 13 kV, the optimum pressures for SXR and HXR emissions of nitrogen gas (N₂) were obtained. At lower voltages, 10, and 11 kV optimum pressure for SXR emission was 3.5 torr while for HXR emission was 2.5 torr. At higher voltages, 12, and 13 kV, the optimum pressures shift to higher values at 4 and 3 torr for SXR and HXR emissions, respectively. Among the applied voltages, the least intensity of both SXR and HXR was at voltage 10 kV and the most intensity was for 13 kV which confirm with increasing voltage, the intensity of X-ray emission increases. Also the results obtained by images of pin-hole camera were in compatible with the results of detected signals by different filtered Pin-diodes and Scintillation detector. Our results illustrate that the voltage and the pressure are effective parameters in X-ray emission from the PF.     

Relationship between profile length and roughness variables for natural surfaces

Surface roughness variables such as the rms height and the correlation length are commonly used as inputs for electromagnetic models to predict the backscattering coefficient. The objective of this study is to investigate the influence of the roughness profile length on the estimation of roughness variables. Surface profiles of 25 m long obtained by a laser profiler have been examined. A clear dependence of exponential type was observed between the roughness variables and the profile length.     

Comprehensive Study on Soft X-Ray Emission from Admixtures of Nitrogen and Neon Gases in the APF Plasma Focus Device

The present work is an investigation on the effect of working gas composition as well as applied voltage and operating pressure on the behavior of SXR emitted from the APF device. Three volumetric ratios(90:10), (75:25), and (50:50) of nitrogen:neon (N₂:Ne) admixture were used with operating conditions at applied voltages of 11, 12, and 13 kV and operating pressures of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 torr. Using (N₂:Ne) gas mixture ratios of (90:10) and (75:25) and at applied voltage of 11 kV, the optimum pressure for maximum intensity of SXR was 3.5 torr. However, for the percentage of (50:50), it shifts to higher pressure of 4 torr. At higher applied voltages of 12 and 13 kV, the optimum pressures shift to higher values, 4 torr for both volumetric ratios (90:10) and (75:25), and 4.5 torr for the ratio of (50:50). It was found that the intensity of SXR increases with the increase of neon (Ne) percentage in the admixture of (N₂:Ne) and applied voltage. The highest intensity was for the volumetric ratio of (50:50) operating at the voltage of 13 kV. Our results illustrated that mixing neon (Ne) with nitrogen (N₂) as the working gas in the PF is a power source of SXR emission.     

Effect of Quartz and Pyrex Insulators Length on Hard-X ray Signals in APF Plasma Focus Device

This paper, presents the variation of hard X-ray (HXR) intensity in the APF plasma focus device for different insulator sleeves. For Pyrex and Quartz insulators, the lengths of 40 and 50 mm seems optimal to yield maximum HXR intensity, respectively. Also using the Pyrex insulator leads to production of higher HXR intensity than the Quartz insulator. The results illustrate that the length and the material of the insulator has a considerable effect on the HXR intensity.     

The effect of morphological modification on the thermoelectric properties of ZnO nanomaterials

At present, huge research efforts are dedicated to improve the efficiency of thermoelectric (TE) materials. Nanostructuring is one of the suggested methods to improve their TE performance. However, the morphology of a nanomaterial might play a significant role on its TE properties. In this work, we demonstrated this effect by producing zinc oxide (ZnO) in two different morphologies using the microwave assisted chemical route. Nanoparticles (NPs) and nanorods (NRs) were synthesised by changing the molar ratios of the starting precursors. The obtained results show that the NRs have improved TE properties compared to those of the NPs, particularly at high temperature. At 673 K the Seebeck coefficient, electrical conductivity and power factor values of the ZnO NRs reached ?1020 μV/K, 22 S/m and 23 μW/m.K², respectively. The NPs have only recorded ?850 μV/K, 3 S/m and 2.4 μW/m.K² of these factors. Moreover, the thermal conductivity of the NRs was found to be three times lower than that of the NPs. As a result of these differences the Figure of Merit (zT) value of the NRs is around 0.012, while that of the NPs is only 0.001. Power generation characteristics of single leg modules made of the ZnO NPs and NRs, measured under the conditions of actual applications in an air atmosphere were also investigated. The output power of the ZnO NRs is found to be several times higher than that of the NPs. These results have clearly demonstrated the effect of nanostructures morphology on the TE performance, which might be important for future TE generators.     

Food neophobia levels of Lebanese and American college students

Food neophobia, defined as the reluctance to eat novel foods, is a personality trait that influences everyday human food choices. The objectives of this work were first, to compare food neophobia levels among American and Lebanese college students (n = 1122), second to assess the effect of personal variables such as country of residence, socio-economic status (SES) on food neophobia levels, and third to examine the effect of food neophobia levels on the familiarity and willingness to try ratings of familiar and novel foods. Average food neophobia scale (FNS) score for all respondents was 33.1 ± 11.3. Differences on FNS scores were obtained between American (29.8) and Lebanese (36.4) students (P < 0.05). Number of trips taken outside the country, frequency of eating ethnic foods and history of sickness after eating a new food were significant (P < 0.05). Food neophilic subjects had higher familiarity and willingness to try scores for familiar and novel foods.     

Assessment of the ASAR sensor radiometric quality in comparison to ERS‐2 and RADARSAT‐1 SAR data

The estimation of geophysical parameters from Synthetic Aperture Radar (SAR) data necessitates well‐calibrated sensors with good radiometric precision. In this paper, the radiometric calibration of the new Advanced Synthetic Aperture Radar (ASAR‐ENVISAT) sensor was assessed by comparing ASAR data with ERS‐2 and RADARSAT‐1 SAR data. By analysing the difference between radar signals of forest stands, the results show differences of varying importance between the ASAR on the one hand, and the ERS‐2 and the RADARSAT‐1 on the other. For recent data acquired at the end of 2005, the difference varies from ?0.72 to +0.72 dB, with temporal variations that can reach 1.1 dB. For older data acquired in 2003 and 2004, we observe a sharp decrease in the radar signal in the range direction, which can attain 3.5 dB. The use of revised calibration constants provided recently by the European Space Agency (ESA) significantly improves the results of the radiometric calibration, where the difference between the ASAR and the other SARs will be lower than 0.5 dB.