Positive Thrust Research Articles

Taxes And Incentives - Moving Targets

Abstract For the fourth time in fifteen years, the oil patch is being forced to deal with a major reform of tax and incentive provisions. Following significant overhauls of the "rules of the game" in 1970, 1975, and 1980, the oil and gas industry is busy trying to sort out the latest series of changes announced in the Western Accord on March 27, 1985 and by the Province of Alberta on June 24. Tax Topics seeks to set out a general overview of these latest changes, which will clearly have an important impact on many of the ways of doing business in Canada. Introduction The Canadian oil and gas industry might be well advised to be wary of the year 1990, considering the apparent trend for this country's law makers to overhaul the fiscal rules of the game every five years. In 1970, the full extent of tax reform was unveiled. Five years later in 1975, the federal and provincial capitals went mildly berserk and implemented dramatic changes to all of the oil and gas rules. In 1980, the now largely defunct NEP made its unwelcome appearance on the scene, with a whole host of new taxes and incentives. And, in 1985 we have witnessed the demise of the NEP, and, once again, new sets of tax rules at both the federal and provincial levels have been devised. The year 1990 might be a good time to be out of the country on sabbatical, if one believes in five-year cycles! Executive Summary This year, the first shoe fell on March 27 when the federal government and the three producing western provinces announced the signing of the Western Accord. That agreement dealt exclusively with changes to federal legislation, and tossed the ball to the producing provinces to make their own tax changes with a similar positive thrust. The second shoe fell almost three months later on June 24 when the Province of Alberta announced changes to the province's royalty and incentive regimes. Federal Changes Very briefly, the Western Accord, in conjunction with Finance Minister Wilson's May 23, 1985 budget, announced the following changes to the fiscal regime facing the oil and gas industry.The Natural Gas and Gas Liquids Tax, the Incremental Oil Revenue Tax, the Canadian Ownership Special Charge, he Petroleum Compensation Charge, and export charges on both product and crude exports are to be repealed.The Petroleum Incentives Program (PIP) is to continue until March 31, 1986.The Petroleum and Gas Revenue Tax (PGRT) will be phased out from 1986 to 1989.Royalties and incentives applicable to operators in the Canada Lands are to be studied.

A correlation between the evolution of mineralizing fluids and the geomechanical development of a shear zone as illustrated by the Henderson 2 Mine, Quebec

Two ore zones, one enclosed within a shear zone (zone B) and the other in a subsidiary structure (zone D). At onset of the shear zone, subsidiary fracture patterns are developed in second order faults in the following sequence. At peak strength Riedel shears are formed which propagate out into the walls of the shear zones producing the zone D structure. After peak strength, restraint (P) shears are developed in the thrust attitude within the shear zone. Principal displacement shears, (D) developed toward residual strength in the direction of movement. The continuation of the shear displacement gives rise to schistosities within the main shear zone. While the main shear zone and the P and D shears within the main shear zone were in continual movement, the subsidiary zone D structure, once formed retained a simple fracture pattern and moved little in comparison to the main shear zone. Mineralizing fluids introduced into this shear environment show a similar pattern of evolution, with a wider range of homogenization and halite disappearance temperatures in the more active zone B than within zone D. Systematic variations of Ca/Na and Ca/Mg indicate migration. --Modified journal abstract.

Activities in vacuum science and technology in the USSR and in Eastern Europe

longitudinally. The outer extremity of the push-rod (2) has a tip (5) and the internal end has a contact (6). A positive thrust onto the surface to be monitored is provided by a spring (7). The contact element (3) and contact (6) of the push-rod (2) complete an electric circuit which incorporates a supply (8) and lamp (9). The component (10) to be monitored is placed under the push-rod (2). The tip (5) of the push-rod (2) makes contact with the wall of the article (10) to be monitored. The contact element (3) touches contact (6) and lamp (9) lights. The detector with the item to be monitored (10) is placed into a vacuum chamber. On reduction of pressure the component increases in size and moves the push-rod (2) thereby moving the mobile contact element (3). The pressure becomes stabilized. The development or presence of medium or small leaks in the wall of the component leads to reduction in its size after a certain time, as a result of which the push-rod (2) under the action of the spring (7) which remains in contact with the wall surface, moves back from the extreme position at which there remains fixed, on account of friction in the support, the contact element (3). The movement away of one of the contacts of the pair leads to a break in the electric circuit, so that the lamp (9) switches off. Thus with the apparatus described it is possible to detect small, medium and large leaks in hermetically-sealed containers with a single detector. Also a large range of sizes of vacuum-tight containers can be monitored.

Activities in vacuum science and technology in the USSR and in Eastern Europe

longitudinally. The outer extremity of the push-rod (2) has a tip (5) and the internal end has a contact (6). A positive thrust onto the surface to be monitored is provided by a spring (7). The contact element (3) and contact (6) of the push-rod (2) complete an electric circuit which incorporates a supply (8) and lamp (9). The component (10) to be monitored is placed under the push-rod (2). The tip (5) of the push-rod (2) makes contact with the wall of the article (10) to be monitored. The contact element (3) touches contact (6) and lamp (9) lights. The detector with the item to be monitored (10) is placed into a vacuum chamber. On reduction of pressure the component increases in size and moves the push-rod (2) thereby moving the mobile contact element (3). The pressure becomes stabilized. The development or presence of medium or small leaks in the wall of the component leads to reduction in its size after a certain time, as a result of which the push-rod (2) under the action of the spring (7) which remains in contact with the wall surface, moves back from the extreme position at which there remains fixed, on account of friction in the support, the contact element (3). The movement away of one of the contacts of the pair leads to a break in the electric circuit, so that the lamp (9) switches off. Thus with the apparatus described it is possible to detect small, medium and large leaks in hermetically-sealed containers with a single detector. Also a large range of sizes of vacuum-tight containers can be monitored.

Installed Performance of Vectoring/Reversing Nonaxisymmetric Nozzles

An experimental program was conducted to determine the internal and installed performance characteristics of five different thrust vectoring and reversing nonaxisymmetric nozzle concepts for tactical fighter aircraft. As part of this program, the nonaxisymmetric nozzles and an advanced axisymmetric baseline nozzle were tested in the AEDC 16-ft transonic Propulsion Wind Tunnel at Mach numbers from 0.4 through 1.5. The twin-nozzle models were mounted to a partially metric jet-effects model, with nozzle exits located at the trailing edge of a fighter wing plan form. Tests were conducted at three unvectored power settings, thrust vector angles up to 30 deg and dry power reverse thrust. Nozzle pressure ratios were varied about nominal values for an advanced turbofan engine cycle at each test Mach number. At unvectored conditions, the nonaxisymmetric nozzles with external expansion surfaces exhibited the highest thrust-minus-drag at both cruise and maneuver conditions. Performance was equal to or better than that of the axisymmetric baseline nozzle. Vectoring was found to improve the lift-to-drag ratio for all nonaxisymmetric nozzles at all positive thrust vector angles. The lift, drag, and pitching moment increments associated with vectoring were shown to correlate well with modified trailing edge flap theory. Reverse thrust levels equalled 50% of forward, dry power thrust at static conditions, with a reversing effectiveness nearly twice this value demonstrated at Mach 0.9.

Stability of a system of three degrees of freedom subjected to a circulatory force

The free vibrations of a uniformly accelerating linear elastic, non-dissipative system of three degrees of freedom, carrying a tip mass and subjected to a constant circulatory thrust applied at a free end, are investigated for the purpose of determining the influence of the orientation of the thrust on the system's state of stability. A dimensionless bi-cubic frequency equation whose coefficients depend upon the tip mass parameter, the thrust parameter, and the tangency coefficient, α, is solved and eigencurves are plotted for several values of α. These eigencurves reveal that, for a certain range of small values of α, the system becomes unstable by divergence for any positive thrust, no matter how small. There also exists a range of α for which the system is first unstable by divergence, secondly stable, and finally unstable by flutter as the magnitude of the thrust is increased. For α sufficiently large, the system is stable for a certain range of values of the thrust, but eventually it becomes unstable by flutter as the thrust is increased beyond its critical value.

低切削速度におけるびびりの安定性

A simple structural model was manufactured to study the cause of chatter stability and the chatter behavior at low cutting speeds. The dynamic cutting force and the vibrational displacement were measured simultaneously during chatter. The present vibrational displacement measured and that at previous rotation of the work are superimposed to give the instantaneous uncut chip thickness, which is compared with the corresponding dynamic cutting force.The observations show that the so-called penetration effect is not liner. A significantly large positive thrust force is observed to act almost instantaneously to supress the vibration as the tool penetrates into the work when the tool relief interferes with the newly cut surface. This effect is more significant as the cutting speed is lower, the tool relief angle is smaller, and the chatter frequency is higher. It is also shown, through measurements of vibrational amplitudes under various cutting conditions, that the interference not only increases the stable cutting width but also supresses the vibrational amplitudes to certain values even though the cutting width is increased.

Surveyor Terminal Guidance

Under the auspices of the Jet Propulsion Laboratory and the National Aeronautics and Space Administration, Hughes Aircraft Company is performing the design and development of the unmanned, lunar softlanding spacecraft system for the Surveyor project. This paper describes the basic concept and implementation of the terminal guidance system for the landing phase.The terminal descent profile consists of a solid rocket deboost phase with earth-based commands for thrust orientation as well as partial control of ignition. This is followed by a closed-loop vernier guidance phase with throttleable liquid engines. The automatic vernier guidance concept consists of (l) velocity magnitude control in accordance with a velocity versus slant range descent law and (2) gravity turn steering. Tie differential equations of motion are solved and implementation requirements obtained for anticipated variations in trajectory and site slope conditions. The on-line earth-based guidance program for solid rocket thrust attitude and ignition control is also discussed.

SHEARING FLOW OF A VISCOELASTIC FLUID BETWEEN POROUS COAXIAL CYLINDERS

course, is that the vehicle should move on a straight line with the thrust pointed in a direction opposite to the velocity vector. The first guess at the thrust attitude, however, is 20° away from this direction. Figure 1 illustrates the thrust attitude histories along successive trials. The discontinuity in slope at a velocity of 2000 fps is due to the fact that the guidance parameters are not recomputed beyond this point. It is not possible to continue the closed-loop calculations to the end of the trajectory, because excessively large control changes would be called for to correct small errors in the terminal quantity. In Table 1, the improvement in pay-off and the error in the terminal constraint are shown. It is seen that most of the improvement is accomplished on the first trial by just coming close to meeting the terminal constraint. After three trials the terminal mass is quite close to the optimum, although the thrust attitude is as much as 5° away from the optimum. Further improvement in thrust attitude produces very little change in terminal mass.

Approximate Solution for Rocket Flight With Linear-Tangent Thrust Attitude Control

Abstract : This note presents an approximate solution to the equations of motion written with linear-tangent thrust attitude control. The usefullness of this solution is evaluated by comparison with accurate numerical integration. This comparison shows that the solution gives accuracies sufficient for preliminary calculations for satellite boost vehicles and has a four speed advantage over numerical integration of the same accuracy level.

Optimum Rocket Trajectories

Some general considerations regarding maximum range missile trajectories are presented. It is shown that under certain simplifying assumptions maximum range is achieved if the thrust attitude angle is held constant during the entire powered flight. This result is exact for a constant gravitational force field if aerodynamic forces and altitude dependence of rocket thrust are neglected. For motion in the earth's inverse square, central force field, constant thrust attitude is a good approximation to the optimum program, provided the distance covered during powered flight is small compared to the radius of the earth. Equations for the value of the optimum attitude angle are presented for both constant and Kepler force fields. The results provide a convenient means of estimating an upper limit for the range which could be achieved with a given missile.

Ventricular aneurysm with calcification of the heart

A case of aneurysm of the anterolateral wall of the left ventricle is reported. The wall of the aneurysm was calcified in its lower part (x-ray demonstration). It expanded during ventricular systole in its upper part causing a typical pattern of paradoxical pulse, proved by electrokymography, and a positive thrust of the chest wall.

THEORETICAL STUDY OF RAM-JET PROPULSION

In ram-jet propulsion, artificial compression before combustion does not exist. Therefore, the only factors which may influence the increase in momentum, i.e., the thrust, are:(1) The degree of initial dynamic compression by a diffuser;(2) The shape of the combustion chamber;(3) The variations of the rate of heat release along the tube;(4) Air excess coefficient;(5) Kind of fuel;(6) Velocity of flight;(7) Aerodynamic and heat losses.This paper deals almost exclusively with the first four factors, i.e., with the theoretical case of an ideal gas and a perfect flow, with no heat or aerodynamic losses involved. The possible appearance of shock waves is disregarded. Neither are boundary layer phenomena discussed in this paper. The external fairing and the relation between the internal and external shape, as well as the influence of this relation on the actually obtainable thrust and efficiency, are also considered to be beyond the scope of the paper. General conclusions are drawn as to the optimum shape of the ideal engine from the standpoint of efficiency. It is found that air should be submitted initially to as high a dynamic compression as possible, i.e., using all kinetic energy available, after which a combustion chamber of constant cross section is used—and finally a nozzle. Another conclusion is that it is impossible to obtain a positive thrust with a combustion chamber of constant cross section, if no dynamic compression, by a diffuser, is initially applied. Special attention is drawn in the paper to the representation and interpretation of the ideal ram-jet cycle on the entropy diagram, this giving a clear picture of the relations between the energy released and the efficiency and thrust obtainable. The fact that in the flow through a tube of constant cross section with heat release (e.g., by combustion), the pressure may decrease even if ideal gas and perfect flow (with no losses involved) are concerned, is emphasized throughout the paper, as it seems that generally this fact is rather overlooked.

SOME RESULTS OF SECTION OF PARTICULAR NERVE BRANCHES TO THE AMPULLÆ OF THE FOUR VERTICAL SEMICIRCULAR CANALS OF THE FROG

SOME RESULTS OF SECTION OF PARTICULAR NERVE BRANCHES TO THE AMPULLÆ OF THE FOUR VERTICAL SEMICIRCULAR CANALS OF THE FROG