Structure and dynamics of the Ceratodon purpureus-Bryum pseudotriquetrum community in the Yukidori Valley, Langhovde, continental Antarctica

The structure and dynamics of the Ceratodon purpureus-Bryum pseudotriquetrum community along the Yukidori Valley, Langhovde near Syowa Station, continental Antarctica have been documented. This moss community showed a clear vegetation structure with a micro-relief distribution, consisting of three different sites; a mound, a slope and a hollow. On the hollow site a sand-covered Bryum pseudotriquetrum patch dominated. On the slope site a pure Ceratodon purpureus patch, a Bryum pseudotriquetrum patch, and a Ceratodon purpureus-Bryum pseudotriquetrum mixed patch abundantly occurred. On the mound site a cyanobacteria-mixed Ceratodon purpureus patch prevailed. The dynamics of this community was basically unclear. However, some change patterns were infered from the results. The sand-covered Bryum pseudotriquetrum patch and the cyanobacteria-mixed Ceratodon purpureus patch generally showed no clear change. It is also speculated that some of the patches of this community undergo cyclic changes. A suggested cyclic pattern is as follows; some of the sand-covered Bryum pseudotriquetrum patches turned on Ceratodon purpureus-Bryum pseudotriquetrum mixed patches, and finally those patches became a cyanobacteria-mixed Ceratodon purpureus patch. Some of them, on the other hand, degraded into sand-covered Bryum pseudotriquetrum patches, probably because of strong wind or water flow. However, more detailed studies will be needed to confirm these inferences

Micro-relief distribution of major mosses in ice-free areas along the Soya Coast, the Syowa Station area, East Antarctica

Micro-relief distribution of five major mosses, Pottia heimii, Ceratodon purpureus, Bryum pseudotriquetrum, Grimmia lawiana and Bryum argenteum, in the ice-free areas along the Soya Coast, continental part of East Antarctica have been compared. Those five mosses showed three different types of micro-relief distribution, at three different types of sites: mounds, slopes and hollows. Pottia heimii and Ceratodon purpureus prevailed on mound sites mixed with cyanobacteria. In dryer mound environments cyanobacteria was supposed to play an important role in nitrogen fixation. Bryum pseudotriquetrum and Grimmia lawiana dominated on hollow sites covered with sand. A more moisture rich condition of the hollow may promote their abundance associated with their high photosynthetic ability at moist sites. Bryum argenteum showed a rather unclear micro-relief distribution pattern. It appeared chiefly on mounds, but on hollows also. Rich nutrient input by sea birds into its habitats may allow various site selection under environments favorable to distribution

Current commands for high-efficiency torque control of DC shunt motor

The current commands for a high-efficiency torque control of a DC shunt motor are described. In the proposed control method, the effect of a magnetic saturation and an armature reaction are taken into account by representing the coefficients of an electromotive force and a torque as a function of the field current, the armature current and the revolving speed. The current commands at which the loss of the motor drive system becomes a minimum are calculated as an optimal problem. The proposed control technique of a motor is implemented on the microprocessor-based control system. The effect of the consideration of the magnetic saturation and the armature reaction on the produced torque and the minimisation of the loss are discussed analytically and experimentally </p

EVALUATION OF EXHAUST GAS FROM BIO-DIESEL FUEL ENGINE

Joint Research on Environmental Science and Technology for the Eart

Vegetation development on the glacier moraines in Oobloyah Valley, Ellesmere Island high arctic Canada

The process of the vegetation development on glacier moraines was surveyed in the lower stream area of Oobloyah Valley (80°50\u27N, 82°45\u27W), Ellesmere Island, high arctic Canada. Four glacier moraines, and an outwash plane with different establishment periods in the proglacial field of Arklio Glacier, were surveyed .The oldest moraine was estimated to have been established during the Full Glacial, ca. 25000-35000 years ago, and the youngest one during the Little Ice Age, ca. 250 years ago. The vegetation properties such as number of species per study plot, cover of vegetation, lichens and bryophytes showed constant increase the moraine age, suggesting directional vegetation development. Changes in the species composition were such that new species successively appeared during the establishment of the moraines without obvious replacement of the species. It was concluded that the manner of the vegetation development was directional-nonreplacement succession even under extreme high arctic environment, differing from the generally accepted view that under an extreme high arctic environment nondirectional-nonreplacement succession prevails. Vegetation physiognomy approached Cassiope tetragona-dominated dwarf shrub heath, which generally prevails in more southern regions than Ellesmere Island. The period required for the vegetation development in the study area was assumed to be quite long, probably at least ca. 20000 years

BIODIESEL PRODUCTION BY ESTERIFICATION OF OLEIC ACID WITH ETHANOL UNDER ULTRASONIC IRRADIATION

Joint Research on Environmental Science and Technology for the Eart