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2D conjugated metal–organic frameworks (2D c‐MOFs) are emerging as electroactive materials for chemiresistive sensors, but selective sensing with fast response/recovery is a challenge. Phthalocyanine‐based Ni2[MPc(NH)8] 2D c‐MOF films are presented as active layers for polarity‐selective chemiresisitors toward water and volatile organic compounds (VOCs). Surface‐hydrophobic modification by grafting aliphatic alkyl chains on 2D c‐MOF films decreases diffused analytes into the MOF backbone, resulting in a considerably accelerated recovery progress (from ca. 50 to ca. 10 s) during humidity sensing. Toward VOCs, the sensors deliver a polarity‐selective response among alcohols but no signal for low‐polarity aprotic hydrocarbons. The octadecyltrimethoxysilane‐modified Ni2[MPc(NH)8] based sensor displays high‐performance methanol sensing with fast response (36 s)/recovery (13 s) and a detection limit as low as 10 ppm, surpassing reported room‐temperature chemiresistors. [ABSTRACT FROM AUTHOR]

Signal processing based on frequency polarity has been attracting wide attention due to its potential applications to industry. It is popular to employ two vector rotators for such signal processing. However, it has very recently been reported that an equivalent signal processing effect can be attained in a much simpler manner using two-input two-output filters in the D-module. This paper further investigates a class of characteristic-varying systems in the D-module, which contains the filters in the D-module as a special case, and gives new analytical results on their properties from the viewpoints of existence, realization, and stability. If the results are applied to filter problems, n-th order filters in the D-module in new forms can be easily and directly obtained, whose stability and response equivalent to the associated filters with vector rotators are guaranteed. If the results are applied to AC motor modeling problems, dynamic models and block diagrams of AC motors in general reference frame are easily and directly obtained. Very general and useful analyses are given for a newly proposed class of characteristic-varying systems in the D-module that have potential usefulness in various industrial applications including control of magnetic bearing system, analyses and active compensations of power systems, and sensorless drives of AC motors. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(1): 39–51, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10171 [ABSTRACT FROM AUTHOR]