Abstract: A method for estimating wear of a drill bit in percussive rock drilling. A percussion device is configured for generating shock waves in a drill bit for breaking rock. The method includes, during drilling determining a percussion frequency of the percussion device; and estimating wear of the drill bit based on the determined percussion frequency of the percussion device and a model representation of the wear of the drill bit as a function of percussion frequency, wherein the model representation is configured to output the estimated wear of the drill bit utilizing the determined percussion frequency as input signal.

Abstract: A new and distinct variety of Exacum plant characterized by double flowers, floriferousness, blooming habits and the sterility of the flower. Plants can be propagated by asexual processes true to type and the rooting ability is excellent. The size of the single flower surpasses the known single cultivars.

Abstract: A new and distinct variety of Exacum plant characterized by double flowers, floriferousness, blooming habits and the sterility of the flower. Plants can be propagated by asexual processes true to type. Rooting ability of the variety is excellent. The size of the flower surpasses that of the known single cultivar.

Abstract: A new and distinct variety of Exacum plant characterized by double flowers, with the normal 5 anthers transformed into a rosette of petals in the center of the flower, floriferousness, blooming habits and the sterility of the flower. Plants can be propagated by asexual processes true to type. Rooting ability of the variety is excellent. The semidouble flower differs from that of the other known cultivars.

Abstract: A new and distinct variety of Exacum plant characterized by semidouble flowers, floriferousness, blooming habits and the sterility of the flower. The normal stamens are petalloid and arranged incurved as a rosette in the center of the lavender-blue-violet flower. Plants can be propagated by asexual processes true to type. Rooting ability of the variety is excellent. The type of flower differs from that of the other known single cultivars.

Abstract: A new and distinctive cultivar of exacum plant particularly characterized by its uniquely colored rose-purple petals not seen in exacum before, the petals surrounding bright yellow-gold stamen, the flower set against a dense, moderately dark green foliage, the plant having a rapid, full and compact growth, a floriferous display of rose-purple flowers that have stamens and style and produce seed, and reproduces easily and consistently by cuttings or by seed.

Abstract: A new cultivar of Exacum plant named Blue Ropendel having attractive single blue-violet flowers, excellent floriferousness, and a cascading growth habit.