Abstract: A method for recovering natural gas from a group of subterranean zones containing natural gas, including injecting an amount of a displacing gas into a first subterranean zone, producing a first produced gas from the first subterranean zone, collecting an amount of the first produced gas wherein the quality of the collected first produced gas is higher than or equal to a threshold production quality for the first produced gas, injecting an amount of the first produced gas into a second subterranean zone wherein the quality of the injected first produced gas is higher than or equal to a threshold injection quality for the first produced gas, producing a second produced gas from the second subterranean zone, and collecting an amount of the second produced gas wherein the quality of the collected second produced gas is higher than or equal to a threshold production quality for the second produced gas.

Abstract: A method for recovering natural gas from a group of subterranean zones containing natural gas, including injecting an amount of a displacing gas into a first subterranean zone, producing a first produced gas from the first subterranean zone, collecting an amount of the first produced gas wherein the quality of the collected first produced gas is higher than or equal to a threshold production quality for the first produced gas, injecting an amount of the first produced gas into a second subterranean zone wherein the quality of the injected first produced gas is higher than or equal to a threshold injection quality for the first produced gas, producing a second produced gas from the second subterranean zone, and collecting an amount of the second produced gas wherein the quality of the collected second produced gas is higher than or equal to a threshold production quality for the second produced gas.

Abstract: An invariant checking method and apparatus using binary decision diagrams (BDDs) in combination with constraint solvers for determining whether a system property is an invariant of a system description. The invariant checking method receives system descriptions and system properties and transforms them into a model formula. Specific variables are eliminated from the model formula and a corresponding output formula is generated. The output formula is transformed into a logic formula by substituting a new logic variable for each integer constraint in the output formula. A constrained BDD is constructed from the logic formula. The constrained BDD uses a heuristic algorithm to order the logic variables in the paths leading to true or false. A constraint solver is applied to the integer constraints that correspond to the occurrences of logic variables in the BDD paths, which determines whether the system property is or is not an invariant of the system description.

Abstract: A method for generating test cases for software and a test case generator comprising a simulator that drives software under test from one input state to the next. The simulator is constrained by predetermined criteria to visit states that meet the criteria thus preserving computer resources. The states reached by the simulator are tested.

Abstract: An accessory for modifying the decay pattern of vibrations set up in an implement to which the accessory is attached, and the combination of a decay pattern modifying accessory and an implement. Methods of manufacturing decay pattern modifying accessories are also disclosed.

Abstract: An invariant checking method and apparatus using binary decision diagrams (BDDs) in combination with constraint solvers for determining whether a system property is an invariant of a system description. The invariant checking method receives system descriptions and system properties and transforms them into a model formula. Specific variables are eliminated from the model formula and a corresponding output formula is generated. The output formula is transformed into a logic formula by substituting a new logic variable for each integer constraint in the output formula. A constrained BDD is constructed from the logic formula. The constrained BDD uses a heuristic algorithm to order the logic variables in the paths leading to true or false. A constraint solver is applied to the integer constraints that correspond to the occurrences of logic variables in the BDD paths, which determines whether the system property is or is not an invariant of the system description.

Abstract: An accessory for modifying the decay pattern of vibrations set up in an implement to which the accessory is attached, and the combination of a decay pattern modifying accessory and an implement. Methods of manufacturing decay pattern modifying accessories are also disclosed.

Abstract: Coating formulations which behave as elastic solids having reversible stress-induced fluidity are prepared by creating a fluid having distributed therein effective amounts of ionic charge sites and countercharge sites. For instance, elastic solids having reversible stress-induced fluidity are prepared by combining liquid formulations with a dispersion of a small, but effective, amount of at least one crystalline mixed metal hydroxide conforming substantially to the formulaLi.sub.m D.sub.d T(OH).sub.(m+2d+3+n.multidot.a) (A.sup.n).sub.a .multidot.xH.sub.2 Owhere m is zero to one, D is a divalent metal, d is from zero to 4, T is a trivalent metal, A represents at least one anion or negative-valence radical of valence n and a is the amount of A, where n is 1 or more, (m+2d+3+n.multidot.a) is equal to or greater than 3, (m+d) is greater than zero, and xH.sub.2 O represents excess waters of hydration, if any.

Abstract: Crystalline layered mixed metal hydroxides (LMMHs) which are substantially free of unbound water and which conform substantially to the general formulaLi.sub.m D.sub.d T(OH).sub.(3+m+d),wherem represents an amount of Li of from 0 to 3,D represents a divalent metal cation, and d represents an amount of D of from 0 to 8.0,T represents a trivalent metal cation, and (3+m+d) represents an amount which substantially satisfies the valence requirements of Li, D and T, andwhere m+d does not equal zero,are prepared, in an organic reaction medium which is essentially free of unbound water, by mixing predetermined metal organo compounds in predetermined ratios and reacting the metal organo compounds with at least one reagent which supplies OH.sup.- ions to replace the beginning anions in the mixture of metal compounds.A preferred LMMH is one which conforms substantially to the generic formula Mg.sub.d Al(OH).sub.(3+d), where d represents the amount of Mg per each unit of Al.

Abstract: This invention is an antistatic polyurethane shoe sole which is prepared by reacting in a closed mold a reaction mixture comprising(a) a relatively high equivalent weight polyester polyol or a relatively high equivalent weight polyether polyol containing about 5-25 weight percent repeating units derived from ethylene oxide and about 75-95 weight percent repeating units derived from a C3-C6 cyclic ether,(b) a chain extender compound, in an amount from about 5 to about 40 parts per 100 parts of component (a),(c) a sufficient amount of a blowing agent to provide a density of about 10 to about 65 pounds per cubic foot,(d) a polyisocyanate, in an amount to provide about 0.9 to about 1.2 isocyanate groups per active hydrogen-containing group present in the reaction mixture, and(e) a non-volatile ionizable metal salt, in an amount from about 0.

Abstract: Butene-1 and ethylene mixtures are made by reacting ethylene with a trialkyl aluminum in a boiling bed reactor. The process is more efficient in that it is selective for making butene-1 and more butene-1 is produced per unit weight of the trialkyl aluminum.

Abstract: A method for preparing C.sub.4 to C.sub.10 .alpha.-olefins employing trialkyl aluminum compounds, in a growth zone having a recirculation rate through an external heat transfer zone such that the contents of the zone are recirculated in a period of time sufficient to remove the heat of the reaction using added lower .alpha.-olefins at 100.degree.-150.degree. C., 200-2000 psig, and 5-90 minute contact time followed by displacement with lower .alpha.-olefins in a static mixer zone to free the growth .alpha.-olefins and regenerate the trialkyl aluminum compounds. The growth .alpha.-olefins are separated with all of the lower .alpha.-olefins recycled to the growth and displacement steps.

Abstract: A method for preparing C.sub.4 to C.sub.10 .alpha.-olefins having a major portion C.sub.6 .alpha.-olefins employing tri alkyl aluminum compounds, e.g., Al(C.sub.2 H.sub.5).sub.3 or Al(C.sub.4 H.sub.9).sub.3 or mixtures of Al(C.sub.2 H.sub.5).sub.3 and Al(C.sub.4 H.sub.9).sub.3 as well as the unmixed C.sub.2, C.sub.4 alkyl aluminum isomers or homologs in the growth step using added ethylene at about 120.degree. C., 500-700 psig, 5-90 minute contact time followed by displacement with C.sub.2 H.sub.4, C.sub.4 H.sub.8, or C.sub.2 H.sub.4 and C.sub.4 H.sub.8 to free the growth alkyl and regenerate the tri alkyl aluminum compounds. The growth .alpha.-olefins are separated with all of the C.sub.2 H.sub.4 recycled to the growth and displacement steps, and part or all of the C.sub.4 H.sub.8 recycled to the displacement step.