Fore Sections Research Articles

Hydrodynamic CharacteristicsAnalysisand Simulation of water GekcoAutonomous underwater Vehicle

The need to explore and characterize the seabed for exploitation of hydrocarbon is imperative as it plays a major role in the development of the Nigerian economy and indeed the economy of Nations. However, to achieve this in a safe, precise and cost-effective manner is a challenge that needed to be addressed. This paper presents the hydrodynamic analysis on the water gecko autonomous underwater vehicle capable of subsea subsoil characterization. The hull developed measures 3.42m long, 0.85 m wide and 0.78 m high. The mid-section of the hull Houses the cone penetration test machine, the fore section, the electronics and batteries and the rear section the hydraulic system and thruster control. Software simulation on the complex hull shape show that the total bare hull resistance is 600N at a speed of 2.4m/s. Also, the hydrodynamic coefficients of the vehicle such as the lift and drag were generated for between -15 to 30 degrees angle of attack and -15 to 15 degrees side slip angles from computational fluid dynamics (CFD) simulation. Open loop maneuverswerecarried out in the surge motion direction and simulation results show that there is a very close proximity between the designed condition and the simulated condition. In the surge motion simulation, which is the bases of the generation of the hydrodynamic coefficients it was observed that whereas a speed of 2.4m/s was used for the generation of the coefficient and a resistance of 600N was seen by the hull at that speed, a speed 2.63m/s was achieved by the vehicle when propeller by four 167N thrusters acting at 26degrees to the longitudinal axis thereby validating the inputs.

고속철도차량 해치시스템 동작 특성을 고려한 제어기 설계

A fore section of a high-speed train best expresses the characteristics of the vehicle and is functional by reducing air resistance. The controller of the existing hatch system is designed as a PLC, so it is possible to modify the control circuit without physically changing wiring or relays. However, it is not standardized as each foreign manufacturer provides software in different languages. Therefore, when a failure of the PLC itself occurs, it is impossible to identify the cause, so there is a disadvantage in that response to system failure is delayed.BRIn this paper, the requirements for the controller were derived through the analysis of the operation characteristics and functions of the existing high-speed train hatch system controller. In addition, the hatch system controller was designed by analyzing the operation sequence of the hatch system. And considering the future improvement of the hatch system, the controller was designed as a PCB type that is easy to expand. The normal operation of the controller was tested by virtually applying the hatch operation input signal and the sensor input signal. As a result of the experiment, it was confirmed that the hatch system status output signal and the pneumatic valve control output signal were controlled according to the hatch system operation sequence.

Sire carcass breeding values affect body composition in lambs — 1. Effects on lean weight and its distribution within the carcass as measured by computed tomography

Data are obtained from computed tomography scanning of 1665 lambs at locations around Australia. Lambs were progeny of Terminal, Maternal and Merino sires with known Australian Sheep Breeding Values for post weaning c-site eye muscle depth (mm; PEMD) and fat depth (mm; PFAT), and post weaning weight (kg; PWWT). Across the 7.8 unit range of sire PEMD, carcass lean weight increased by 7.7%. This lean was distributed to the saddle section (mid-section) where lean became 3.8% heavier, with fore section lean becoming 3.5% lighter. Reducing sire PFAT across its 5.1 unit range increased carcass lean weight by 9.5%, and distributed lean to the saddle section which was 3.7% heavier. Increasing sire PWWT increased lean at some sites in some years, and on average increased saddle lean by 4% across the 24.7 unit PWWT range. Changes in lean weight and distribution due to selection for carcass breeding values will increase carcass value, particularly through increased weight of high value loin cuts.

The correlation of intramuscular fat content between muscles of the lamb carcass and the use of computed tomography to predict intramuscular fat percentage in lambs

Intramuscular fat (IMF) % contributes positively to the juiciness and flavour of lamb and is therefore a useful indicator of eating quality. A rapid, non-destructive method of IMF determination like computed tomography (CT) would enable pre-sorting of carcasses based on IMF% and potential eating quality. Given the loin muscle (longissimus lumborum) is easy to sample, a single measurement at this site would be useful, providing is correlates well to other muscles. To determine the ability of CT to predict IMF%, this study used 400 animals and examined 5 muscles from three sections of the carcass: from the fore-section the m. supraspinatus and m. infraspinatus, from the saddle-section the m. longissimus lumborum and from the hind-section the m. semimembranosus and m. semitendinosus. The average CT pixel density of muscle was negatively associated with IMF% and can be used to predict IMF% although precision in this study was poor. The ability of CT to predict IMF% was greatest in the m. longissimus lumborum (slope −0.07) and smallest in the m. infraspinatus (slope −0.02). The correlation coefficients of IMF% between the five muscles were variable, with the highest correlation coefficients evident between muscles of the fore section (0.67 between the m. supraspinatus and the m. infraspinatus) and the weakest correlations were between the muscle of the fore and hind section. The correlation between the m. longissimus lumborum to the other muscles was fairly consistent with values ranging between 0.34 and 0.40 (partial correlation coefficient). The correlation between the proportion of carcass fat and the IMF% of the five muscles varied and was greatest in the m. longissimus lumborum (0.41).

Flow Control on a NACA 4418 Using Dielectric-Barrier-Discharge Vortex Generators

Streamwise oriented Dielectric-Barrier-Discharge plasma actuators were used on a NACA 4418 airfoil for flow separation control at and 95 k. Rows of symmetric and asymmetric actuators were located on the fore section of the suction surface, which were designed to create counterrotating and corotating streamwise vortex arrays, respectively. These could completely reattach the flow in the downstream of the actuators for at , and for at . The drag coefficient was reduced by 63% at and the lift coefficient increased by 67%, while the symmetric actuators performed slightly better than the asymmetric actuators overall. Streamwise vortices appeared to play a key role at low angles of attack, although the flow reattachment is believed to be primarily due to a strong suction into the plasma. Furthermore, these streamwise actuators outperformed a pair of spanwise actuators over the same chord-wise locations.

The monitoring programme of the ecological and ecotoxicological consequences of the “Erika” oil spill

On December 11, 1999, Erika, an oil tanker flying the Maltese flag and loaded with 31 000 t of heavy fuel oil, was making its way from Dunkirk to Livorno when it encountered difficult weather conditions Southwest of the Brittany coast gale force winds 8 to 9 and 6 mwaves). On the morning of 12th December, the captain broadcast an SOS; his vessel was breaking in two, approximately 30 nautical miles to south of Penmarc'h Point (Fig. 1; Finistere, France). The fore section of the vessel sank during the night of the 12-13 December and the aft section was taken in tow on the morning December 13, but subsequently sank in the early afternoon. Both parts lay in 120 m of water and were located 10 km apart. Approximately, 19 000 t of heavy fuel oil were spilled into the sea. The first of the fuel oil came ashore on December 23 and major strandings took place between December 24 and 27. The Loire Atlantique and Vendee coasts were severely contaminated and the departements of Finistere, Morbihan, and Charente Maritime in the South, were in no way spared. Violent winds blowing at right angles to the coast accompanied extremely high tides washed the pollution high up the beach strand, reaching the tops of cliffs more than 10 m high. The struggle at sea against the pollution began on December 15 and 1200 t of fuel were recovered within the next fortnight. Between mid May and late summer 2000, a little more than 10 000 t of heavy fuel oil were fluidised by adding colza methyl ester and pumped from the tanks of the sunken vessel, while an additional 1200 t were pumped out during final cleaning. A total of 12 400 t of the originally transported 31 000 t were retrieved from both the sea and the wreck and a little less than 19 000 t were released into the environment...

Aerodynamic Entropy Generation Rate in a Boundary Layer With High Free Stream Turbulence

Aerodynamic Entropy Generation Rate in a Boundary Layer With High Free Stream Turbulence

Fishing lure with sound attraction

A fishing lure is disclosed having a body with two sections that move relative to one another. An aft section is connected via a shaft to a fore section and is slidable toward and away from the aft section along the shaft as the lure is pulled through the water. A contact post mounted on a rear end of the fore section or a fore end of the rear section impacts the other section as the lure is pulled through the water producing a clicking or popping sound which attracts fish.

Studies on the mode of action of non‐starch‐polysaccharides (NSP)‐degrading enzymes in vitro

By use of an in vitro model, the effects of NSP‐degrading enzymes on the cage effect and the hydration properties were demonstrated using wheat bran. The in vitro model simulates the conditions (pH, dry matter, temperature and transit time) in the fore sections of the porcine gastro‐ intestinal tract (GIT) by neglecting endogenous enzyme activities. Enzyme treatment caused a dose‐dependent increase in wheat bran solubility and thus resulted in improved protein and mineral release from the insoluble NSP fraction. Up to 17% protein and 40% crude ash from the insoluble NSP‐fraction were dissolved after enzyme treatment. Hydrating properties of wheat bran were strongly affected by enzyme treatment and particle size. Water‐binding capacity (WBC) and water‐holding capacity (WHC) decreased with increasing enzyme dosage in dependence on particle size. The studies confirmed the applicability of the tested in vitro model as a useful tool for preliminary tests to estimate the effects of NSP‐degrading enzymes on nutrient release and changes in some physico‐chemical properties.

Studies on the mode of action of non‐starch‐polysaccharides (NSP) degrading enzymes in vitro

An in vitro model using the model substance wheat bran as NSP source was developed to study the effects of NSP degrading enzymes (xylanase and β3‐glucanase) on NSP fractions. The in vitro model simulates the conditions (pH, dry matter, temperature and transit time) in the fore sections of the porcine gastrointestinal tract. By neglecting endogenous enzymes the sole effect of the added enzymes could be investigated. By application of the enzyme complex, a significant degradation of the insoluble NSP fraction was observed in all sections of the porcine gastro‐intestinal tract simulated by the in vitro model. A strong dose dependent effect was determined. Compared to the control, the arabinose/xylose‐ratio generally increased but differences were found between the sections simulated. Considering the arabinoxylans in the soluble NSP fraction, the effect of enzyme supplementation was reflected by a change in the arabinose and xylose contents. In comparison to the control, an increase in the amounts of arabinose and xylose was observed at low enzyme doses applied. However, with increasing enzyme activities the amount of arabinose and xylose declined. The in vitro model is considered as a useful tool for preliminary tests to estimate the effects of NSP‐degrading enzymes on NSP fractions in the fore sections of the porcine gastro‐intestinal tract.

Numerical simulation of spacecraft charging by impact‐induced plasmas during a cometary flyby

The European Space Agency spacecraft Giotto will encounter comet Halley in March 1986 with a relative velocity of 69 km s−1. The fore section of the surface will be bombarded by neutral molecules which will produce secondary electrons and sputtered ions; a plasma cloud will form around the spacecraft, and its surface will be electrically charged. This paper summarizes the results which have been obtained from a numerical simulation of this phenomenon. It is found that a conductive spacecraft will reach a positive potential of the order of 10 V and that a positive potential barrier will develop in the close vicinity of the emitting surface, provided the flux of sputtered ions is sufficient. The charging time constant is approximately equal to the ion plasma period determined by the large ion density in front of the spacecraft. The electron distribution around the spacecraft is nearly isotropic, but the ion diffusion is limited to the forward direction. Thus a well‐defined ion wake forms behind the spacecraft. Some numerical aspects of the simulations are also discussed. In particular, it is found that the simulation of spacecraft charging by impact‐generated plasmas with the real ion masses is not prohibitively expensive using modern computers.

Interpretation of the measurements of secondary electron currents induced by impacts during the flyby of comet Halley

The Giotto, Vega-1 and Vega-2 spacecraft flew through the environment of comet Halley at a relatively close range with velocities of the order of 70–80 km/s. The fore sections of their surface were bombarded by neutral molecules and dust grains which caused the emission of secondary electrons and sputtered ions. This paper makes use of the secondary electron current measurements performed on Vega-1 to infer some characteristic features of the cometary atmosphere. The total gas production rate is estimated to be of the order of 10 30 molecules/s and is found to vary with time; the presence of a major jet is also detected at closest approach.

Impact induced plasma during a cometary fly-by

GIOTTO, the probe which is presently developed by the European Space Agency, will encounter comet Halley in March 1986 with a relative velocity of 69 km/s. The fore section of the surface will be submitted to the bombardment of dust grains and neutral molecules in the final phase of the mission, like that of an Earth orbiter during atmospheric re-entry. These particles have a kinetic energy of 24 eV per a.m.u.; they produce secondary ions and electrons which form a plasma cloud around the body and control the electric potential of its surface. This paper is a review of the work which has been performed on the subject by dedicated study groups; the purpose of their action was to gather information and produce new findings which might have an influence on the design of the spacecraft and help in the interpretation of the data collected by the scientific payload. The effect of impact induced plasma may already be significant at 10 5 km from the comet nucleus; at a distance of 1000 km the flux of ions and electrons produced by cometary dust and neutrals will possibly exceed that of the ambient plasma by more than three orders of magnitude. It is expected that the spacecraft surface potential will be positive and will reach at least a few tens of volts; coating the leading surface of the spacecraft with a thin layer of gold or silver will help reducing the emission of ions from neutral gas. Computer simulation models are used to predict the structure of the charged particle density distribution in the vicinity of the surface. Effects associated with the wake and differential charging are also discussed. The significance of these results is conditioned by the validity of the models and the largest source of uncertainty seems to be associated with the plasma generated by dust impact.