Fluid thrust control system

A pure fluid thrust control system is described for a pump-fed, regeneratively cooled liquid propellant rocket engine. A proportional fluid amplifier and a bistable fluid amplifier control overshoot in the starting of the engine and take it to a predetermined thrust. An ejector type pump is provided in the line between the liquid hydrogen rocket nozzle heat exchanger and the turbine driving the fuel pump to aid in bringing the fluid at this point back into the regular system when it is not bypassed. The thrust control system is intended to function in environments too severe for mechanical controls

Beam-Based Alignment of the NuMI Target Station Components at FNAL

The Neutrinos at the Main Injector (NuMI) facility is a conventional horn-focused neutrino beam which produces muon neutrinos from a beam of mesons directed into a long evacuated decay volume. The relative alignment of the primary proton beam, target, and focusing horns affects the neutrino energy spectrum delivered to experiments. This paper describes a check of the alignment of these components using the proton beam.Comment: higher resolution figures available on Fermilab Preprint Server (see SPIRES entry), accepted for publication in Nucl. Instr. and Meth.

Influence of different drying parameters on the composition of volatile compounds of thyme and rosemary cultivated in Sardinia

The shelf life of spices is traditionally extended by drying. Fresh herbs, due to their high water content, undergo microorganism growth and adverse biochemical reactions. On the other hand drying may result in a lot of physical and chemical alterations. Air and oven-dehydration are the main methods used to stabilize spices. During oven drying, in general, losses of volatile compounds are directly dependent on the temperature and time used. This paper deals with the effect of different drying temperatures and air fluxes on the volatiles in rosemary (Rosmarinus officinalis L.) and thyme (Thymus officinalis L.) cultivated in Sardinia. Fresh leaves were collected and soon divided in two batches, which were subjected to hydro distillation and GC-MS analysis, the first batch as fresh, the second one after drying in a laboratory pilot dryer. Three drying temperatures were used, 30, 38 and 45°C, and for each one two airflow rates were set. The fresh and dried plant material were hydro distilled for 4 hours using a Clevenger-type apparatus (Italian Official Pharmacopeias X). The oils (liquid and light yellow) were recovered directly from above the distillate without adding any solvent and stored at –20°C before analyses, which were carried out on two replicates of each sample by gas chromatography, using a flame ionization detector. The diluted samples were injected using a split/splitless automatic injector (using 2,6-dimethylphenol as internal standard). Qualitative analysis was done by GC/Mass and mass units were monitored from 10 to 450 at 70 eV. Results of the influence of the different drying conditions on volatile compounds of the two herbs will be reported

Numerical Analysis of Methane Direct Injection in a Single-cylinder 250 cm3 Spark Ignition Engine

The paper shows the results of the numerical tasks of a study aimed to evaluate the potential of low-pressure (< 20 bar) direct injection systems for internal combustion engines fed with gaseous fuels. Starting from the geometry of a low-cost commercial injector already available for GDI uses, a 2D axisymmetric CFD analyses is performed to assess the influence of injection pressure and valve and seat-valve profiles on jet characteristics, methane-air mixing, and charge distribution at ignition time. Then 3D simulations for the motorcycle single cylinder test-engine are carried out considering as much as possible combustion chamber details and realistic boundary conditions. Although it is possible identifying which operating and geometrical details of injection system are able to support complete mixture homogeneity, this study shows tremendous difficulties, in case of gaseous fuels, to realise satisfactory stratification charges that would be required to obtain satisfactory performance at partial loads

PROSPECTS FOR MULTI-TEV TWO-BEAM LINEAR COLLIDERS*

Recent work at CERN and SLAC has opened the possibility of the development of concrete designs for electron positron linear colliders that have a center of mass energy substantially above 1 TeV [1,2]. These designs are based on high gradient, normal conducting acceleration with the power provided by an auxiliary beam that is efficiently accelerated in a fully loaded, low frequency linac. This type of power source offers a flexibility to develop linear collider designs that have a wide range of parameters. In particular, the choice of frequency can be made without regard to the availability of high power RF sources, at least up to about 30 GHz. This paper explores possible linear collider designs taking into account limits on acceleration gradient and beambeam effects. The study shows that electron positron linear colliders have an energy reach far in excess of 1 TeV. In particular we show that an X-band linear collider powered with conventional sources might be upgraded using two-beam techniques to an energy far above 1 TeV. Thus, the linear collider offers a platform for continued exploration at the energy frontier of High Energy Physics.

Effects of intake flow and coolant temperature on the spatial fuel distribution in a direct-injection gasoline engine by PLIF technique

The spatial fuel distributions of the homogeneous and stratified charge of a high pressure 6-hole injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of in-cylinder charge motion, fuel injection pressure and coolant temperature were investigated using a planar laser induced fluorescence (PLIF) technique. It was found that in the case of homogeneous charge mode, early injection in the intake stroke generated similar fuel distributions at the crank angle of 12° BTDC regardless of the in-cylinder air motion at the coolant temperature of 90 °C. In the case of stratified charge mode, the in-cylinder tumble flow played more effective role in mixture preparation than the swirl flow during the compression stroke; and the increase of the coolant temperature improved fuel evaporation; but the increase of the fuel supplying pressure could not change the pattern of the fuel vapour distribution against the expectation

Design of an automobile turbocharger gas turbine engine

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (leaf 24).The turbocharger gas turbine engine was designed with the intent of being built as a demonstration for the Massachusetts Institute of Technology Department of Mechanical Engineering courses 2.005 and 2.006 to supplement material covered. A gas turbine operates on an open version of the Brayton cycle and consists of a compressor, a combustion chamber and a turbine. An automobile turbocharger was chosen because it contains a compressor and turbine on a common shaft. Designs for the combustion chamber, oil system, fuel system, and ignition system were created based on research of similar projects. Many of the necessary parts were also specified.by Keane T. Nishimoto.S.B

EVEREST IST - 2002 - 00185 : D23 : final report

Deliverable públic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version

Application of PSVR-DNS Algorithm for Attacker Detection and Isolation

The DNS (Domain Name System) is used to map and convert human-friendly domain names to the numeric IP (Internet Protocol) addresses. As with the operation of any communication system, there are some security risks associated with the operation of DNS. Actions targeting the availability or stability of a network\u27s DNS service are considered DNS attack. For example, a high volume of traffic and a large number of requests coming to DNS servers are part of a type of DoS (Denial of Service) attack that uses DNS for amplification. Although most DNS servers are open source, some commercial protective DNS services are available for network traffic control, filtering and automatic blocking of requests to undesirable, dangerous or malicious internet domains, but the price of such services is high. In this paper, a new PSVR-DNS (Probability Support Vector Regression-Domain Name System) algorithm is proposed for the purpose of detecting and isolating attackers who pose a threat to an uninterrupted work of the DNS servers. The main focus is on the prevention of the DNS cache poisoning. The collected results showed that the proposed PSVR-DNS algorithm achieves better performance related to faster detection and isolation of attacks compared to some existing algorithms