Abstract: An estimation system includes an estimator estimating a state of a controlled object on the basis of a plurality of pieces of sensor information representing a state in a periphery of sensors, detected by a plurality of the sensors, and a model regarding the controlled object controlled by the estimation system, and a controller generating a control command for operating the controlled object such that the controlled object acts toward a predefined control target on the basis of the estimated result.

Abstract: A cylinder primary air filter element is coaxially disposed within a cylindrical shell between an air intake pipe and an outlet provided in the shell. A resilient secondary air filter element is deformably secured in an opening formed in a sidewall of the shell so as to be located outside the outer periphery of the primary air filter. The secondary filter element is secured in place by a filter element retaining plate which is arcuately shaped so as to be concentric with the primary filter element and is readily detachably attached to the shell. A sufficiently enlarged air flow passageway is thus defined between the outer periphery of the primary air filter element and the filter element retaining plate and consequently the resistance encountered by the air flowing through this passageway may be considerably reduced and the excessive bulging of the air cleaner may be avoided. A reed valve assembly is connected to the outlet of a housing which surrounds the secondary filter element.