Abstract: An externally controlled fan drive includes a fluid clutch that alters torque delivered to a fan housing to rotate the fan housing at a target fan speed. An adaptive controller measures the actual fan speed and adaptively updates the control logic to compensate for variable physical characteristics of the fan device.

Abstract: A method is disclosed for estimating clutch engagement characteristics of a friction clutch system in a vehicle powertrain. A dynamic model of the system is used under conditions that cause clutch slipping. Algebraic equations defining a functional relationship between clutch torque and an engagement angle have characteristic parameters that are estimated using a non-linear least squares technique. A non-linear least squares technique iteratively minimizes the difference between a measured output clutch disk speed and an output clutch disk speed from the system dynamic model for the same inputs until a small insignificant error is reached. Parameter estimates are used to compile an estimated clutch engagement characteristic.

Abstract: A system and method for facilitating an automatic rolling upgrade of distributed software. In a set of computing devices (e.g., a cluster), each node executes the distributed program, but different nodes may operate any number of different versions of the program. During a rolling upgrade of the software, the nodes all operate according to a specified acting version of the software. A node attempting the join the cluster may be required to have a software version at least equal to the acting version. When all nodes have been upgraded to a version newer than the current acting version, the acting version is reset to the lowest software version installed on a node. The rolling upgrade completes automatically when all nodes run at a specified software version (e.g., the most recent) or have the same version installed.

Abstract: A method is disclosed for estimating clutch engagement characteristics of a friction clutch system in a vehicle powertrain. A dynamic model of the system is used under conditions that cause clutch slipping. Algebraic equations defining a functional relationship between clutch torque and an engagement angle have characteristic parameters that are estimated using a non-linear least squares technique. A non-linear least squares technique iteratively minimizes the difference between a measured output clutch disk speed and an output clutch disk speed from the system dynamic model for the same inputs until a small insignificant error is reached. Parameter estimates are used to compile an estimated clutch engagement characteristic.

Abstract: Various systems and methods for drift compensation are disclosed. As one example, a system for compensating drift in a control circuit is disclosed that includes at least two control signals. One of the control signals is provided by a circuit that is susceptible to drift. This control signal is provided both to a systems or device under control, and to a detection circuit. The detection circuit is operable to detect a drift in the control signal. In addition, the detection circuit provides another control signal that varies as a function of the drift in the received control signal.

Abstract: Techniques are provided for managing replicated data items in a cluster of shared nothing nodes. The techniques include synchronously propagating changes to one or more replicas, while asynchronously propagating changes to the remaining replicas. Because the replicas to which the change is synchronously replicated may be a relatively small percentage of the total number of replicas, the overhead associated with performing an update is reduced. The process of selecting which nodes are involved in the synchronous update operation may take into account a variety of factors, including which replicas are available at the time the update operation is being performed.

Abstract: A group of shared-storage resources are being maintained as replicas by the nodes of a cluster. Each node in the cluster maintains a set of pointers to the members of the group. As membership changes, the set of pointers should be changed accordingly. For various, reasons, the set of pointers of a node are not changed and may point to shared-storage resources that are no longer members of the group and/or not point to shared-storage resources that are members of the group. By recording a history of membership changes in the shared-storage resources, and comparing the recording to what a node thinks the shared resources should be, an incorrect set of pointers can be detected and corrective active undertaken.

Abstract: An externally controlled fan drive includes a fluid clutch that alters torque delivered to a fan housing to rotate the fan housing at a target fan speed. An adaptive controller measures the actual fan speed and adaptively updates the control logic to compensate for variable physical characteristics of the fan device.

Abstract: A reconfigurable variable blank-holder force system (and method) for producing sheet metal stampings comprises a portable hydraulic unit, controlled by a digital control system and a knowledge-based expert system to enable reconfigurability and an easy transition from the try-out stage to production. The knowledge-base has a hierarchical structure and includes stored information about part geometry, material properties and press parameters. The expert system enables an operator to determine optimal blank-holder forces, and to fine-tune through a graphical interface unit. The optimal blank-holder forces are generated by hydraulic force actuators, using a controller running a nonlinear algorithm that accounts for valve nonlinearities, variable flow-rate and numbers of operational cylinders. The portable hydraulic unit preferably comprises hydraulic cylinders with quick disconnect hoses, a manifold, servo-valves and a pump unit.

Abstract: Less-restrictive techniques are provided for ensuring that replicated-data systems will never provide out-of-date version of data items. A replicated-data system maintains (1) a version number, (3) a membership group identifier, and (6) a membership count, with each replica of a data item. These values are maintained in such a way as to allow the replicated-data system to reliably satisfy some read requests even though half, or less than half, of the replicas of the data item are available.

Abstract: A system and techniques are described for managing key-value pairs using an architecture that does not restrict its users to any specific platform or storage subsystem. According to one aspect of the invention, the repository is portable in that the architecture need not change based on the environment and platform in which the repository is used. Rather, the portion of the architecture that is platform-specific is limited to plug-ins at a storage abstraction layer of the repository. The plug-ins expose the same storage abstraction interface to the other layers of the repository, but are implemented to interact with different platforms and storage subsystems. Consequently, in response to being ported from one platform to another, the repository may simply change the plug-in to invoke for persistent storage operations.

Abstract: A system and techniques are described for managing key-value pairs using an architecture that does not restrict its users to any specific platform or storage subsystem. According to one aspect of the invention, the repository is portable in that the architecture need not change based on the environment and platform in which the repository is used. Rather, the portion of the architecture that is platform-specific is limited to plug-ins at a storage abstraction layer of the repository. The plug-ins expose the same storage abstraction interface to the other layers of the repository, but are implemented to interact with different platforms and storage subsystems. Consequently, in response to being ported from one platform to another, the repository may simply change the plug-in to invoke for persistent storage operations.

Abstract: An aspect of the invention provides a method for managing information associated with a hierarchical key. A plurality of hash tables are created for a plurality of levels of a hierarchy associated with a hierarchical key, wherein each hash table is associated with a corresponding level of the hierarchy. Entries are stored within each of the plurality of hash tables, wherein the entries are associated with key names that have as many levels as the level associated with the respective hash table. Furthermore, a reference to a descendant entry that is in a respective hash table may be stored within each entry.

Abstract: A system and method for facilitating an automatic rolling upgrade of distributed software. In a set of computing devices (e.g., a cluster), each node executes the distributed program, but different nodes may operate any number of different versions of the program. During a rolling upgrade of the software, the nodes all operate according to a specified acting version of the software. A node attempting the join the cluster may be required to have a software version at least equal to the acting version. When all nodes have been upgraded to a version newer than the current acting version, the acting version is reset to the lowest software version installed on a node. The rolling upgrade completes automatically when all nodes run at a specified software version (e.g., the most recent) or have the same version installed.

Abstract: A method and mechanism for managing data to resolve incompatibilities between different versions of data is disclosed. According to one approach, incompatibilities to private data is managed using group/member dependent key(s)/link(s), static shared data is managed using group/member dependent key(s)/link(s), and dynamic shared data is managed using data transformation function(s).

Abstract: Disclosed is a method, mechanism, and computer usable medium for managing and accessing static and shard data. In one approach, described is a method and mechanism for implementing group dependent keys (GDKs) in a computing system, in which the GDK is visible to all members of a distributed system, but its value(s) and subtree(s) could be different for different groups. Members of each group see the same view of the value and subtree of a GDK. Also disclosed is a method, mechanism, and computer usable medium for implementing group dependent links (GDLs) in a computing system. According to one approach, a data transformation function is used to coordinate changes to different versions of shared data.

Abstract: A system and techniques are described for managing key-value pairs using an architecture that does not restrict its users to any specific platform or storage subsystem. According to one aspect of the invention, the repository is portable in that the architecture need not change based on the environment and platform in which the repository is used. Rather, the portion of the architecture that is platform-specific is limited to plug-ins at a storage abstraction layer of the repository. The plug-ins expose the same storage abstraction interface to the other layers of the repository, but are implemented to interact with different platforms and storage subsystems. Consequently, in response to being ported from one platform to another, the repository may simply change the plug-in to invoke for persistent storage operations.

Abstract: Systems and methods for supporting and maintaining a distributed global map of transaction identifiers at the gateway processes using a hashing algorithm configured on each application process to access the global maps. A global map of transaction identifiers that associates global transaction identifiers with remote local transaction identifiers is maintained at each gateway process. When an application process performing work for a particular transaction desires to export the transaction to a remote node, a hashing function configured on the application process is applied to the global transaction identifier associated with the particular transaction. Application of the hashing function to the global transaction identifier identifies one of the gateway processes. The global transaction identifier is stored to the global map associated with that gateway process.