354 research outputs found

    Design of an inlet track of a small I.C. engine for swirl enhancement

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    The purpose of this project was to re-design the inlet port of a small Internal Combustion Engine in order to enhance the production of turbulence by swirl. A good swirl promotes fast combustion and improves the efficiency. A small internal combustion engine was designed to be part of a very efficient vehicle to enter a consumption marathon. The engine should run at low speeds, in order to have low mechanical losses but the combustion should be fast, enabling good combustion efficiency. Therefore high turbulence should be produced prior to combustion within the cylinder, so swirl was induced by the inlet channel within the cylinder head. To perform this task the help of three software programs is required, Solid Works, Gambit and Fluent. The first was required to produce the CAD-geometry. To build the geometry it is important to bear in mind that there are some restrictions for casting and fuel injection. In the next step, Gambit meshes the geometry in the design by using a volume mesh. At last; Fluent calculates the flow within the engine by using a suitable turbulence model. Initially the current geometry was tested and proved to create low swirl, so the geometry was changed several times until reaching a good result in terms of generated swirl. The tests include just steady flow, where the air enters the inlet port and leaves the bottom of the cylinder continuously. The flow within the cylinder is examined at specific sections, namely at various heights of the cylinder (horizontal sections) and pathlines are also evaluated. The flow is calculated for various valve lifts at a specific engine condition.Fundação para a Ciência e a Tecnologia (FCT) - POCI/EME/59186/2004MIT Portugal Program - MIT-Pt/EDAM-SMS/0030/200

    Wafer-based aberration metrology for lithographic systems using overlay measurements on targets imaged from phase-shift gratings

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    In this paper, a new methodology is presented to derive the aberration state of a lithographic projection system from wafer metrology data. For this purpose, new types of phase-shift gratings (PSGs) are introduced, with special features that give rise to a simple linear relation between the PSG image displacement and the phase aberration function of the imaging system. By using the PSGs as the top grating in a diffraction-based overlay stack, their displacement can be measured as an overlay error using a standard wafer metrology tool. In this way, the overlay error can be used as a measurand based on which the phase aberration function in the exit pupil of the lithographic system can be reconstructed. In practice, the overlay error is measured for a set of different PSG targets, after which this information serves as input to a least-squares optimization problem that, upon solving, provides estimates for the Zernike coefficients describing the aberration state of the lithographic system. In addition to a detailed method description, this paper also deals with the additional complications that arise when the method is implemented experimentally and this leads to a number of model refinements and a required calibration step. Finally, the overall performance of the method is assessed through a number of experiments in which the aberration state of the lithographic system is intentionally detuned and subsequently estimated by the new method. These experiments show a remarkably good agreement, with an error smaller than 5¿¿m¿ , among the requested aberrations, the aberrations measured by the on-tool aberration sensor, and the results of the new wafer-based method

    Risk analysis of marine activities in the Belgian part of the North Sea (RAMA): final report

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    RAMA is a 2-year project (04/2004 - 04/2006) executed by two Belgian partners, Ecolas NV (Environmental Consultancy Agency) and the Maritime Institute (University of Ghent), and financed by the SPSD II research program, specific actions, of the Belgian Science Policy (BELPSO). RAMA aims to assess the environmental risks of spills by commercial shipping activities on the Belgian Part of the North Sea. Shipping patterns, transports of dangerous goods, probability of risks and the potential impact of spill incidents (oil & hazardous and noxious substances) will be assessed. The risk analysis within this project studies both the chances of a spill accident happening and the environmental impacts in case of an accident. The valorisation of the RAMA project will result in a thorough analysis of the current status of the shipping at the North Sea in relation to the issue of safety. The scope of the project will however go beyond the mere result of a fundamental risk analysis of the commercial shipping at the North Sea. It is also aiming at the formulation of recommendations to improve the safety level for the environment and at an optimization of response in the framework of the Belgian "North Sea Disaster Plan"

    Rpgrip1 is required for rod outer segment development and ciliary protein trafficking in zebrafish

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    The authors would like to thank the Royal Society of London, the National Eye Research Centre, the Visual Research Trust, Fight for Sight, the W.H. Ross Foundation, the Rosetrees Trust, and the Glasgow Children’s Hospital Charity for supporting this work. This work was also supported by the Deanship of Scientific Research at King Saud University for funding this research (Research Project) grant number ‘RGP – VPP – 219’.Mutations in the RPGR-interacting protein 1 (RPGRIP1) gene cause recessive Leber congenital amaurosis (LCA), juvenile retinitis pigmentosa (RP) and cone-rod dystrophy. RPGRIP1 interacts with other retinal disease-causing proteins and has been proposed to have a role in ciliary protein transport; however, its function remains elusive. Here, we describe a new zebrafish model carrying a nonsense mutation in the rpgrip1 gene. Rpgrip1homozygous mutants do not form rod outer segments and display mislocalization of rhodopsin, suggesting a role for RPGRIP1 in rhodopsin-bearing vesicle trafficking. Furthermore, Rab8, the key regulator of rhodopsin ciliary trafficking, was mislocalized in photoreceptor cells of rpgrip1 mutants. The degeneration of rod cells is early onset, followed by the death of cone cells. These phenotypes are similar to that observed in LCA and juvenile RP patients. Our data indicate RPGRIP1 is necessary for rod outer segment development through regulating ciliary protein trafficking. The rpgrip1 mutant zebrafish may provide a platform for developing therapeutic treatments for RP patients.Publisher PDFPeer reviewe

    Organometallic complexes for nonlinear optics.66. Synthesis and quadratic nonlinear optical studies of trans-[Ru{C=C{2,5-C4H2S-( E )-CH=CH}n-2,5-C4H2S(NO2 )}Cl(dppe)2](n1/40-2)

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    Oligo(2,5-thienylenevinylene)s (OTVs) end-functionalized with a ligated ruthenium alkynyl unit as adonor and a nitro as acceptor, namelytrans-[Ru{C^C-2,5-C4H2S(NO2)}Cl(dppe)2](Ru1T),trans-[Ru{C^C-2,5-C4H2S-(E)-CH]CH-2,5-C4H2S(NO2)}Cl(dppe)2](Ru2T), andtrans-[Ru{C^C-2,5-C4H2S-(E)-CH]CH-2,5-C4H2S-(E)-CH]CH-2,5-C4H2S(NO2)}Cl(dppe)2](Ru3T), have been synthesized, their elec-trochemical properties have been assessed by cyclic voltammetry (CV), their linear optical and quadratic nonlinear optical (NLO) properties have been assayed by UVeviseNIR spectroscopy and hyper-Rayleighscattering studies at 1300 nm, respectively, and their linear optical properties in the formally RuIII state have been examined by UVeviseNIR spectroelectrochemistry. The data for Ru1T-Ru3Thave beencompared to those of the oligo(p-phenylenevinylene) (OPV) analoguestrans-[Ru(C^C-1,4-C6H4NO2)Cl(dppe)2](Ru1P),trans-[Ru{C^C-1,4-C6H4-(E)-CH]CH-1,4-C6H4NO2}Cl(dppe)2](Ru2P), andtrans-[Ru{C^C-1,4-C6H4-(E)-CH]CH-1,4-C6H4-(E)-CH]CH-1,4-C6H4NO2}Cl(dppe)2](Ru3P). The RuII/IIIoxidationpotentials decrease on proceeding fromRu1TtoRu3T, while the wavelength of the UVevislmaxbandincreases on proceeding fromRu1TtoRu2T, but thereafter decreases on further progression toRu3T, similar trends to those seen proceeding fromRu1PtoRu3P. The quadratic nonlinearityb1300 increases on OTV lengthening from Ru1TthroughRu2TtoRu3T; the data are significantly larger than those of the Ru1PeRu3Panalogues which peak atRu2P. The formally RuIIIcomplexes exhibit low-energy bands thatred-shift significantly on proceeding fromRu1TtoRu3T. Computational studies employing time-dependent density functional theory were undertaken on model complexes to rationalize the optical observations and explore the impact of further OTV bridge lengthening. Computational studies on modelcomplexesRu1T′-Ru6T′are consistent with decreasing contributions of the electron donor (ligated Ru) and acceptor (NO2) groups to the HOMO and LUMO, respectively, up n-bridge lengthening.btotvalues increase on progression fromRu1T′toRu3T′, but thereafter further bridge lengthening affords little further increase in b-tot, consistent with a saturation in quadratic NLO response.We thank the Australian Research Council (ARC: DP170100408),the National Natural Science Foundation of China (51432006), theChinese Government Ministry of Education, and the Chinese Gov-ernment State Administration of Foreign Experts Affairs (111 Proj-ect: B13025). J. D. thanks the China Scholarship Council and theAustralian National University for a CSC-ANU PhD Scholarship

    Ten-year outcomes of a randomised trial of laparoscopic versus open surgery for colon cancer

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    Background: Laparoscopic surgery for colon cancer is associated with improved recovery and similar cancer outcomes at 3 and 5 years in comparison with open surgery. However, long-term survival rates have rarely been reported. Here, we present survival and recurrence rates of the Dutch patients included in the COlon cancer Laparoscopic or Open Resection (COLOR) trial at 10-year follow-up. Methods: Between March 1997 and March 2003, patients with non-metastatic colon cancer were recruited by 29 hospitals in eight countries and randomised to either laparoscopic or open surgery. Main inclusion criterion for the COLOR trial was solitary adenocarcinoma of the left or right colon. The primary outcome was disease-free survival at 3 years, and secondary outcomes included overall survival and recurrence. The 10-year follow-up data of all Dutch patients were collected. Analysis was by intention-to-treat. The trial was registered at ClinicalTrials.gov (NCT00387842). Results: In total, 1248 patients were randomised, of which 329 were Dutch. Fifty-eight Dutch patients were excluded and 15 were lost to follow-up, leaving 256 patients for 10-year analysis. Median follow-up was 112 months. Disease-free survival rates were 45.2 % in the laparoscopic group and 43.2 % in the open group (difference 2.0 %; 95 % confidence interval (CI) −10.3 to 14.3; p = 0.96). Overall survival rates were 48.4 and 46.7 %, respectively (difference 1.7 %; 95 % CI −10.6 to 14.0; p = 0.83). Stage-specific analysis revealed similar survival rates for both groups. Sixty-two patients were diagnosed with recurrent disease, accounting for 29.4 % in the laparoscopic group and 28.2 % in the open group (difference 1.2 %; 95 % CI −11.1 to 13.5; p = 0.73). Seven patients had port- or wound-site recurrences (laparoscopic n
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