Abstract: Whether a document file is tampered and the like can be determined without imposing a burden on a user. A hash value calculation unit 103 adds contents of update to an original document as incremental update in order of update, and calculates a hash value of the document file for each of the original document and a document for adding the updated content and a hash value of a document file the hash value and the document file ID, identifying the document file, of which are registered in a blockchain network. An ID acquisition unit 102 acquires the document file ID identifying a received document file, from the document file. A hash value acquisition unit 105 acquires the hash value stored in the latest block among blocks storing the document file IDs from the blockchain network. A tampering determination unit 106 determines whether the document file is tampered by determining whether the hash value calculated and the hash value acquired from the blockchain network 300 match.

Abstract: An aircraft apparatus may include an outer membrane and an inner flexible bladder. The flexible bladder may include a lighter-than-air lifting gas therein, and an interstitial space between the outer membrane and the inner flexible bladder may include air. Various techniques are disclosed for preventing or reducing physical contact between the outer membrane and the inner flexible bladder, reducing an amount of leakage of the lighter-than-air lifting gas.

Abstract: An unmanned lighter-than-air aircraft includes an outer membrane, a flexible bladder within the outer membrane and containing a lighter-than-air gas, a region disposed between the outer membrane and flexible bladder, a volume detection device configured to measure the volume of the flexible bladder, a pressure adjustment device to adjust the pressure within the region, and pressure control circuitry to control the region pressure adjustment device based on measurements from the volume detection device. The aircraft is maintained at a desired altitude, and the volume of the flexible bladder is measured. The pressure within the region is then adjusted by the pressure control circuitry to maintain the volume of the flexible bladder at a desired volume less than its maximum volume, equalizing its pressure with that of the region to reduce lighter-than-air gas leakage from the flexible bladder.

Abstract: An electronic-document-container-data-file generating method for generating a data file using a computer where the data file is to be read by a playback program operating on a computer includes: acquiring at least electronic document data as content data; generating editable memo data as content data, the memo data being associated with the acquired electronic document data; generating a container portion configured to hold a plurality of items of content data including the acquired electronic document data and the generated memo data; generating definition information for defining a method for playing back and/or a method for editing the plurality of items of content data during playback by the playback program; and generating an electronic-document-container data file including the generated container portion and the generated definition information.