Abstract: A fluid flow model is comprised of one cross-flow style core holder and a multitude of standard style core holders, all connected by a concurrent combination of serial and parallel flow paths. The sum of these flow paths yields a fluid flow model that closely approximates a small radial slice of a conventional reservoir. The fluid flow model has particular applicability to estimate the requisite treatment fluid for use in acidizing as well as water control methods.

Abstract: Methods for the treatment of subterranean wells involving injecting a first fracturing fluid into a formation, and then injecting at least a second fracturing fluid into the formation in order to create extended conductive channels through a formation are described. The fracturing fluids can be similar in density, viscosity, pH and the other related characteristics. Alternatively, the fracturing fluids can differ in their densities, viscosities, and pH, allowing for variations in the conductive channels formed. Propping agents can also be included in one or both of the injected fluids, further enhancing the conductive channels formed. The described methods aid in minimizing proppant flowback problems typically associated with hydraulic fracturing techniques.

Abstract: A drafting tool for use in drafting or work layout is made of a pocket-sized piece of flat, transparent, rectangular material. The opposite edges are marked with full-scale and half-scale rulers and a center line is marked connecting the mid points of these rulers. This center line is perpendicular to both reference edges, and at least one of the rulers is marked with units in increasing dimension toward both ends of the reference edge starting with zero at the center line. The base line of a protractor is spaced inwardly from one of the reference edges and is parallel to that reference edge. The protractor itself is layed out in the form of a trapezoid, the top of which is parallel to the base line and the two sides of which slope inwardly from the base line toward the top at forty-five degree angles. The connections of these sides with the top is at an angle of sixty degrees with the base line measured at the origin on opposite sides of the center line.

Abstract: An apparatus for securely positioning thin work pieces for accurate joining of edges using a standard woodworker's bench plane. The plane slides on its side surface on a lower platen surface, and the blade is guided in a very straight path for the cut by a vertical surface which contacts the portion of the sole of the plane lateral to the blade. Work pieces are secured against an upper platen surface by a clamping bar, which is attached by screws at its ends to the platen. Between the clamping bar and the work piece there is a clamping caul, which applies adjustable spaced clamping forces to the work piece by means of individual screws through the clamping bar.Attachable planing fence and miter gage accessories are also disclosed, which permit accurate repeat positioning for taper, cross-grain, and length cuts at selectable angles.

Abstract: The vise system has a bracket section which can be secured to any flat horizontal work surface, particularly a drill press platen, with sliding and rotating degrees of freedom with respect to a bracket bolt. The bracket bolt threads into a hole in the work surface and can tighten down to rigidly hold the bracket section in position. A vise section, capable of clamping a work piece between fixed and movable jaws, is connected to the bracket section by a horizontally-oriented connecting bolt, about which the vise section can rotate, and which can be tightened to secure the vise section at any selected angle. The vise section has a rectangular cross-section, facilitating rapid self-indexing of angles 0, 90, 180, and 270 degrees with respect to the bracket section. The vise system is capable of being pivoted to a position in which the vise section extends beyond the edge of the work surface in order to accommodate work pieces in orientations which would otherwise interfere with the work surface.

Abstract: A circuit to drive electromagnetically actuated displays. The circuit maintains a precise current level regardless of variations in supply voltage and drive coil resistance. The inductance of the drive coil is utilized to increase the efficiency of the current control.

Abstract: A lawn mower (2) is moveably supported by wheels (14) and (16). Wheels (14) and (16) are eccentrically mounted on front and rear link members (24) and (28) which are respectively joined together in pairs by through axles (30). Two flexible cables (32) and (34) transmit this rotation from one front link member (24) to one rear link member (28). One of the link members (24) and (28) is coupled by a flexible cable (80) to a selectively operable control (60) for effecting manual rotation of all of the link members (24) and (28). This effects a change in the height of the wheels (14) and (16) relative to housing (4) simultaneously.

Abstract: A grass catcher assembly (2) for use on a lawn mower comprises a flexible bag (4). The bag (4) includes an open front side (14) and an open top side (16). A cover (40) is pivotally secured to bag (4) adjacent the rear wall (12). Cover (40) includes a chute (50) that has a frictional engagement with a bag frame (38) for securing cover (40) in place. When cover (40) is pivoted upwardly, grass can be dumped from bag (4) through both the open front and top sides (14) and (16) when bag (4) is tipped forwardly.

Abstract: A starting interlock system for power equipment having a cam rotatable between two positions corresponding to energization modes of the equipment and a lever for holding the cam in each position. The cam has two cam surfaces, each of which is engaged by a separate one of two contact surfaces on the lever. The cam is pivotally mounted in a housing on the power equipment operator handle and the housing has an opening for insertion of a key into engagement with the cam to facilitate manual rotation of the cam. In a first energization mode, the lever must be continually manually held by the operator to retain the cam against rotation. Upon release of the lever, the cam pivots to a position corresponding to a second energization mode where it is locked against rotation until the lever is again manipulated by the operator. In the first energization mode, the key is retained within the housing, and cannot be removed.

Abstract: The separation between aircraft approaching a common runway is minimized by measuring the existing wind conditions at a preselected point relative to the runway threshold and basing a prediction of the movement of wake vortices on the measured conditions. The prediction of vortex movement is based upon a vortex advisory algorithm prepared from a plot of wind conditions which predictably remove vortices from the flight path.

Abstract: In a lawn and garden implement, a starting system is provided therefor which prevents accidental energization of the implement, and which also provides for automatic deenergization of the implement upon release thereof by the operator. The starting system includes an actuator lever engaging a switch actuator to rotate a removable key inserted within a rotary operated switch to open and close the implement's circuitry. Lockout means are provided which engage the switch actuator and which must be disengaged therefrom to permit actuator rotation. The component parts of the present invention all cooperate sequentially to provide a starting system which will not energize the implement unless the operator consciously follows the proper starting sequence.