Fuel leak detection on large transport airplanes

Fuel leakage has the risk of being ignited by external ignition sources, and therefore it is important to detect any fuel leakage before the departure of the aircraft. Currently, there are no fuel leak detection systems installed on commercial aircrafts, to detect fuel tank leakage, while only a small number of more recent aircraft, have a fuel monitoring system, that generates a fuel leak-warning message in cockpit in the case of fuel imbalance between the tanks. The approach proposed in this paper requires the fuel vent ports on the wings to be replaced with fuel vent valves, which can be controlled to be in open or close position. The fuel vent valve will be in close position, when certain conditions are fulfilled (all the related fuel valves closed, pumps not operating, etc.), the fuel tank ullage area is then pressurized to 4 psi and the rate of change of the pressure is measured over a period. Several experiments have been conducted and, the result show that a continuous fuel leak of one liter per minute can be detected. Further experiments show that if the fuel tank is pressurized to higher pressures, a fuel leak can be detected sooner

Cargo compartment fire extinguishing system

In all large passenger transport airplanes, halon fire bottles are used to extinguish fire in the cargo compartments. Halon as a fire-extinguishing agent, contributes to the destruction of stratospheric ozone in the atmosphere and it is banned in many countries. FAA considers halon 1301 as an effective firefighting agent due to its low toxicity and noncorrosive properties but because it damages the ozone layer, it has been phased out of production. However, it is still widely used on commercial aircraft until a suitable replacement is found. In this paper we will present an alternative approach to using halon 1301 as a fire fighting paradigm. In the proposed method, nitrogen is first extracted from the atmosphere by using the onboard air separator module it is then cooled, and pressurized into the cargo compartments to suppress any fire. Several methodologies can be used to increase the flow rate from the air separator module, to extinguish fire in cargo compartment

Fourth Amendment Accommodations: (UN)Compelling Public Needs, Balancing Acts, and the Fiction of Consent

The problems of public housing-including crime, drugs, and gun violence- have received an enormous amount of national attention. Much attention has also focused on warrantless searches and consent searches as solutions to these problems. This Note addresses the constitutionality of these proposals and asserts that if the Supreme Court\u27s current Fourth Amendment jurisprudence is taken to its logical extremes, warrantless searches in public housing can be found constitutional. The author argues, however, that such an interpretation fails to strike the proper balance between public need and privacy in the public housing context. The Note concludes by proposing alternative consent-based regimes that would pass constitutional muster

Lateral and normal forces between patterned substrates induced by nematic fluctuations

We consider a nematic liquid crystal confined by two parallel flat substrates whose anchoring conditions vary periodically in one lateral direction. Within the Gaussian approximation, we study the effective forces between the patterned substrates induced by the thermal fluctuations of the nematic director. The shear force oscillates as function of the lateral shift between the patterns on the lower and the upper substrates. We compare the strength of this fluctuation-induced lateral force with the lateral van der Waals force arising from chemically structured adsorbed monolayers. The fluctuation-induced force in normal direction is either repulsive or attractive, depending on the model parameters.Comment: 9 pages, 9 figure

Computable randomness is about more than probabilities

We introduce a notion of computable randomness for infinite sequences that generalises the classical version in two important ways. First, our definition of computable randomness is associated with imprecise probability models, in the sense that we consider lower expectations (or sets of probabilities) instead of classical 'precise' probabilities. Secondly, instead of binary sequences, we consider sequences whose elements take values in some finite sample space. Interestingly, we find that every sequence is computably random with respect to at least one lower expectation, and that lower expectations that are more informative have fewer computably random sequences. This leads to the intriguing question whether every sequence is computably random with respect to a unique most informative lower expectation. We study this question in some detail and provide a partial answer

Band ratios matrix transformation (BRMT): A sedimentary lithology mapping approach using ASTER satellite sensor

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Remote sensing imagery has become an operative and applicable tool for the preparation of geological maps by reducing the costs and increasing the precision. In this study, ASTER satellite remote sensing data were used to extract lithological information of Deh-Molla sedimentary succession, which is located in the southwest of Shahrood city, Semnan Province, North Iran. A robust and effective approach named Band Ratio Matrix Transformation (BRMT) was developed to characterize and discriminate the boundary of sedimentary rock formations in Deh-Molla region. The analysis was based on the forward and continuous division of the visible-near infrared (VNIR) and the shortwave infrared (SWIR) spectral bands of ASTER with subsequent application of principal component analysis (PCA) for producing new transform datasets. The approach was implemented to ASTER spectral band ratios for mapping dominated mineral assemblages in the study area. Quartz, carbonate, and Al, Fe, Mg –OH bearing-altered minerals such as kaolinite, alunite, chlorite and mica were appropriately mapped using the BRMT approach. The results match well with geology map of the study area, fieldwork data and laboratory analysis. Accuracy assessment of the mapping result represents a reasonable kappa coefficient (0.70%) and appropriate overall accuracy (74.64%), which verified the robustness of the BRMT approach. This approach has great potential and capability for mapping sedimentary succession with diverse local–geological–physical characteristics around the world

Comparison of in-situ delay monitors for use in Adaptive Voltage Scaling

In Adaptive Voltage Scaling (AVS) the supply voltage of digital circuits is tuned according to the circuit's actual operating condition, which enables dynamic compensation to PVTA variations. By exploiting the excessive safety margins added in state-of-the-art worst-case designs considerable power saving is achieved. In our approach, the operating condition of the circuit is monitored by in-situ delay monitors. This paper presents different designs to implement the in-situ delay monitors capable of detecting late but still non-erroneous transitions, called Pre-Errors. The developed Pre-Error monitors are integrated in a 16 bit multiplier test circuit and the resulting Pre-Error AVS system is modeled by a Markov chain in order to determine the power saving potential of each Pre-Error detection approach

Bimetallic Zeolite Beta Beads with Hierarchical Porosity as Brønsted-Lewis Solid Acid Catalysts for the Synthesis of Methyl Lactate

Bimetallic zeolite Beta in bead format and containing Al sites with Brønsted acid behavior and Sn, Zr or Hf sites with Lewis acid character, were prepared using a two-step synthetic route. First, zeolite Beta in the format of macroscopic beads (400 to 840 μm) with hierarchical porosity (micropores accessed through meso- and macropores in the range of 30 to 150 nm) were synthesized by hydrothermal crystallization in the presence of anion-exchange resin beads as hard template and further converted into their H-form. Next, the zeolite beads were partially dealuminated using different concentrations of HNO3 (i.e., 1.8 or 7.2 M), followed by grafting with one of the above-mentioned metals (Sn, Zr or Hf) to introduce Lewis acid sites. These bimetallic zeolites were tested as heterogeneous catalysts in the conversion of dihydroxyacetone (DHA) to methyl lactate (ML). The Sn-containing zeolite Beta beads treated by 1.8 M HNO3 and grafted with 27 mmol of SnCl4 (Sn-deAl-1.8-Beta-B) demonstrated the best catalytic activity among the prepared bimetallic zeolite beads, with 99% selectivity and 90% yield of ML after 6 h at 90 °C. This catalyst was also tested in combination with Au-Pd nanoparticles supported on functionalized carbon nanotubes (CNTs) as multifunctional catalytic system for the conversion of glycerol to ML, achieving 29% conversion of glycerol and 67% selectivity towards ML after 4.5 h at 140 °C under 30 bar air. The catalytic results were rationalized by means of a thorough characterization of the zeolitic beads with a combination of techniques (XRD, N2-physisorption, SEM, XRF, TEM, UV-vis spectroscopy and pyridine-FT-IR)

Palenque de San Basilio in Colombia: genetic data support an oral history of a paternal ancestry in Congo

The Palenque, a black community in rural Colombia, have an oral history of fugitive African slaves founding a free village near Cartagena in the seventeenth century. Recently, linguists have identified some 200 words in regular use that originate in a Kikongo language, with Yombe, mainly spoken in the Congo region, being the most likely source. The non-recombining portion of the Y chromosome (NRY) and mitochondrial DNA were analysed to establish whether there was greater similarity between present-day members of the Palenque and Yombe than between the Palenque and 42 other African groups (for all individuals,n= 2799) from which forced slaves might have been taken. NRY data are consistent with the linguistic evidence that Yombe is the most likely group from which the original male settlers of Palenque came. Mitochondrial DNA data suggested substantial maternal sub-Saharan African ancestry and a strong founder effect but did not associate Palenque with any particular African group. In addition, based on cultural data including inhabitants' claims of linguistic differences, it has been hypothesized that the two districts of the village (Abajo and Arriba) have different origins, with Arriba founded by men originating in Congo and Abajo by those born in Colombia. Although significant genetic structuring distinguished the two from each other, no supporting evidence for this hypothesis was found