1,470 research outputs found

    Formation flight investigation for highly efficient future civil transport aircraft

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    Formation flight could greatly assist the air transport industry in tackling the challenges of environmental impact, excessive reliance on fuel and overcapacity. Previous studies have shown drag reductions leading to significant fuel savings for aircraft in formation relative to their solo flight. Safety is guaranteed with the use of extended formation distances, and practical implementation issues could be solved in the near future. Since studies so far have focused on existing aircraft configurations and technology, a case study using a strut-braced wing airliner was carried out to ascertain its applicability to less conventional craft. The present results did not indicate such clear-cut benefits. If formation flight is to be successful and beneficial for the next generations of aircraft, it will be vital to consider its interaction with new technologies developed for highly efficient operation, in particular those aimed at reduction of aircraft drag such as laminar flow, and to do so early in the design of aerospace vehicles and wider systems

    Adenocarcinoma of small bowel

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    Small bowel cancer is one of the rarest cancers in the gastrointestinal tract. The diagnosis is usually late and most patients presented with the advanced stage. Because of this rarity, there is limited data when making decisions for treatment and biological behavior. Most forms of the cancer occur in the duodenum with surgery being the treatment of choice if the cancer is operable. Chemotherapy has an accepted role in duodenal cancer, with the best form being regimen, which yields the best result in combination with capecitabin and oxaliplatin. Our case patient was present with liver metastasis and a huge mass in her first duodenal region so we were required to use chemotherapy and radiotherapy. Like other duodenal cancers, the metastasis decreased her survival and she died about 13 months after diagnosis. © 2015 P. Fadavi and M. Zare

    The new record of the spotted catfish Arius maculates (Thunberg 1792) from Persian Gulf, Iran

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    The species Arius maculates (Thunberg 1792) (Siluriformes, Ariidae) is recorded for the first time from the muddy shores of the inter-tidal zone of Bandar Abbas, Persian Gulf, Iran in February 2011. In this study, the morphological features of Arius maculates are described. This species has previously been recorded from Gulf of Oman to Indonesia, north to Japan (locality type). This finding considerably extends our knowledge of the distribution of Arius maculates

    Effect of pulsed power on particle matter in diesel engine exhaust using a DBD plasma reactor

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    Nonthermal plasma (NTP) treatment of exhaust gas is a promising technology for both nitrogen oxides (NOX) and particulate matter (PM) reduction by introducing plasma into the exhaust gases. This paper considers the effect of NTP on PM mass reduction, PM size distribution, and PM removal efficiency. The experiments are performed on real exhaust gases from a diesel engine. The NTP is generated by applying high-voltage pulses using a pulsed power supply across a dielectric barrier discharge (DBD) reactor. The effects of the applied high-voltage pulses up to 19.44 kVpp with repetition rate of 10 kHz are investigated. In this paper, it is shown that the PM removal and PM size distribution need to be considered both together, as it is possible to achieve high PM removal efficiency with undesirable increase in the number of small particles. Regarding these two important factors, in this paper, 17 kVpp voltage level is determined to be an optimum point for the given configuration. Moreover, particles deposition on the surface of the DBD reactor is found to be a significant phenomenon, which should be considered in all plasma PM removal tests

    Compressible flow structures interaction with a two-dimensional ejector: a cold-flow study

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    An experimental study has been conducted to examine the interaction of compressible flow structures such as shocks and vortices with a two-dimensional ejector geometry using a shock-tube facility. Three diaphragm pressure ratios ofP4 =P1 = 4, 8, and 12 have been employed, whereP4 is the driver gas pressure andP1 is the pressure within the driven compartment of the shock tube. These lead to incident shock Mach numbers of Ms = 1:34, 1.54, and 1.66, respectively. The length of the driver section of the shock tube was 700 mm. Air was used for both the driver and driven gases. High-speed shadowgraphy was employed to visualize the induced flowfield. Pressure measurements were taken at different locations along the test section to study theflow quantitatively. The induced flow is unsteady and dependent on the degree of compressibility of the initial shock wave generated by the rupture of the diaphragm

    Spin-squeezing and Dicke state preparation by heterodyne measurement

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    We investigate the quantum non-demolition (QND) measurement of an atomic population based on a heterodyne detection and show that the induced back-action allows to prepare both spin-squeezed and Dicke states. We use a wavevector formalism to describe the stochastic process of the measurement and the associated atomic evolution. Analytical formulas of the atomic distribution momenta are derived in the weak coupling regime both for short and long time behavior, and they are in good agreement with those obtained by a Monte-Carlo simulation. The experimental implementation of the proposed heterodyne detection scheme is discussed. The role played in the squeezing process by the spontaneous emission is considered

    Nano-Fe3O4/O2: Green, Magnetic and Reusable Catalytic System for the Synthesis of Benzimidazoles

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    Magnetic nano-Fe3O4 was applied in the presence of atmospheric air as a green, efficient, heterogeneous and reusable catalytic system for the synthesis of benzimidazoles via the reactions of o-phenylenediamine (1 eq) with aryl aldehydes (1 eq) in excellentyields (85–97 %) and short reaction times (30–100 min) with a proposed mechanism.Keywords: Benzimidazole, benzene-1,2-diamine, aldehyde, nano-Fe3O4, heterogeneous catalyst, magnetite, O

    High-order harmonic generation from polyatomic molecules including nuclear motion and a nuclear modes analysis

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    We present a generic approach for treating the effect of nuclear motion in the high-order harmonic generation from polyatomic molecules. Our procedure relies on a separation of nuclear and electron dynamics where we account for the electronic part using the Lewenstein model and nuclear motion enters as a nuclear correlation function. We express the nuclear correlation function in terms of Franck-Condon factors which allows us to decompose nuclear motion into modes and identify the modes that are dominant in the high-order harmonic generation process. We show results for the isotopes CH4_4 and CD4_4 and thereby provide direct theoretical support for a recent experiment [Baker {\it et al.}, Science {\bf 312}, 424 (2006)] that uses high-order harmonic generation to probe the ultra-fast structural nuclear rearrangement of ionized methane.Comment: 6 pages, 6 figure

    Suspended liquid particle disturbance on laser-induced blast wave and low density distribution

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    The impurity effect of suspended liquid particles on the laser-induced gas breakdown was experimentally investigated in quiescent gas. The focus of this study is the investigation of the influence of the impurities on the shock wave structure as well as the low density distribution. A 532 nm Nd:YAG laser beam with an 188 mJ/pulse was focused on the chamber filled with suspended liquid particles 0.9 ± 0.63 μm in diameter. Several shock waves are generated by multiple gas breakdowns along the beam path in the breakdown with particles. Four types of shock wave structures can be observed: (1) the dual blast waves with a similar shock radius, (2) the dual blast waves with a large shock radius at the lower breakdown, (3) the dual blast waves with a large shock radius at the upper breakdown, and (4) the triple blast waves. The independent blast waves interact with each other and enhance the shock strength behind the shock front in the lateral direction. The triple blast waves lead to the strongest shock wave in all cases. The shock wave front that propagates toward the opposite laser focal spot impinges on one another, and thereafter a transmitted shock wave (TSW) appears. The TSW interacts with the low density core called a kernel; the kernel then longitudinally expands quickly due to a Richtmyer-Meshkov-like instability. The laser-particle interaction causes an increase in the kernel volume which is approximately five times as large as that in the gas breakdown without particles. In addition, the laser-particle interaction can improve the laser energy efficiency
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