Abstract: An apparatus for controlling a level of gas in a closed environment from a gas supply having a gas sensor for detecting the level of gas in the closed environment. The apparatus has a valve in communication with the gas supply which is automatically opened without human interaction, monitoring and adjustment to release gas from the gas supply into the environment when the level of gas in the environment goes below a first predetermined level and which is automatically closed without human interaction, monitoring and adjustment to stop gas from being released from the gas supply into the environment when the level of gas in the environment goes above a second predetermined level. A method for controlling a level of gas in a closed environment from a gas supply. A refuge chamber.

Abstract: A method include receiving, at a first cache device, a request to send a first asset to a second device; determining whether the first asset is stored at the first cache device; when the determining whether the first asset is stored at the first cache device indicates that first asset is not stored at the first cache device, obtaining, at the first cache device, the first asset, performing a comparison operation based on an average inter-arrival time of the first asset with respect to the first cache device and a characteristic time of the first cache device, the characteristic time of the first cache device being an average period of time assets cached at the first cache device are cached before being evicted from the first cache device, and determining whether or not to cache the obtained first asset at the first cache device based on the comparison; and sending the obtained first asset to the second device.

Abstract: The data cache unit includes a separate fill buffer and a separate write-back buffer. The fill buffer stores one or more cache lines for transference into data cache banks of the data cache unit. The write-back buffer stores a single cache line evicted from the data cache banks prior to write-back to main memory. Circuitry is provided for transferring a cache line from the fill buffer into the data cache banks while simultaneously transferring a victim cache line from the data cache banks into the write-back buffer. Such allows the overall replace operation to be performed in only a single clock cycle. In a particular implementation, the data cache unit is employed within a microprocessor capable of speculative and out-of-order processing of memory instructions. Moreover, the microprocessor is incorporated within a multiprocessor computer system wherein each microprocessor is capable of snooping the cache lines of data cache units of each other microprocessor. The data cache unit is also a non-blocking cache.