Current issue: 58(4)
The influence of horizontal whole-body vibration of fairly low intensity alone and combined with the mental load and motor action typical for the forest machine drive on heart rate variability (HRV), respiration rate (RR) and heart rate (HR) was studied by testing five subjects. Horizontal vibration had an influence on HR, HRV and RR. ’Control activities’ had the most influence on RR and HRV, but some influence on HR, too. ’Moving the control devices’ (motor action) gave the same response in HR as ’control activities’, but not in HRV and RR. ’Control activities’ together with ’vibration’ had a more effect on HRV and RR than these two factors singly, but not on HR. The possibilities of using these variables in field studies are discussed.
The PDF includes a summary in Finnish.
Light and economic FM-CW radar has been developed for controlling the bearing capacity of ice roads and landings on ice used for timber transportation and storage of timber in Finland. It was tested on natural ice and ice roads of three lakes in Southern Finland and one location on sea on the southren coast of Finland (a total of 166 observations). Ice thickness varied from 0 to 100 cm. Correlation coefficient between auger and radar measured ice thickness was r=0.99 and absolute error varied from -10 to +7 cm. The quality of ice had no influence, but by improving the interpretation of results, also the quality factors might be detected.
The PDF includes a summary in Finnish.
The areas of soil cultivation in regeneration sites using different methods in 1976–1979 and the cultivation units in use in Finland in 1979 were studied by means of a questionnaire. Application of soil cultivation methods appears to have become strongly polarized: in Southern Finland disc plowing with wheel tractors are used, whilst in Northern Finland wing plowing with crawler tractors is the most popular method, each being practically the only alternative in the respective area.
The PDF includes a summary in English.
The safety clothing, rubber safety boots, belt with lifting hooks and personal protectors can weight about 3 kg more than the normal work clothing including rubber boots. In order to evaluate the increase off the physical strain in logging work due to them, laboratory tests performed on tread mill were made. The physical strain increased 3–11% as estimated from heart rate and 4–8% as estimated from oxygen consumption measurements.
The PDF includes a summary in English.
This investigation studies the effect of the retail price and the technical properties of preference ordering of buyers of power saw. According to the model derived, the preference ordering of power saws is due to technical properties xj. If no such restrictions in the function are supposed that could have bearing on the preferences of the buyers, there may be N ! possible combinations, when there are N power saws. If one can presume that each price corresponds with a technical level it is possible that each buyer has an optimum price of his own. The bigger the difference between the optimum and actual price, the less preferred the actual power saw is. In this case one may notice the amount of possible orderings is much less than that based on the model. Thus, the mode may be used.
In this paper some models are presented for cases when only n pieces of the population of N power saws are studied. 16 power saws of differing ages and technical levels were investigated. It was noted that many criteria of technical goodness were positively intercorrelated. The price correlated positively with every criterium used. According to the profile analysis, it was concluded that there were many development lines. For example, the idea of a light and the idea of an effective power saw.
According to the principal component analysis, it seemed obvious that there was little room for one- or two-dimensional preference ordering by the technical properties and price.
The PDF includes a summary in English.
Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes the principles of bookkeeping and maintenance of forestry equipment, which reform was in progress in 1938.
The article describes the evolution of sawmills, focusing on four parts: the frame and sliding devices, the fastening of the blade into the frame, appliances for fastening the timber, and feeding devices. The earlier equipment had adaptability that has been lost in the more developed equipment, because the raw materials have been too expensive and hard to acquire, among other things. It is remarked that many inventions of the sawmills have not been adopted in the actual equipment.
The PDF includes a summary in English.
Cable yarding is a general solution for load handling on sites not accessible to ground-based machinery, and is typically associated with steep terrain. On flat terrain, such conditions can primarily be found on soft or wet soils, most frequently encountered in Central and Northern European countries. Today, changed environmental and market conditions may offer an unprecedented opportunity to the actual implementation of cable yarding on flat terrain in commercial operations. The study goal was to collect cable yarder manufacturers experience regarding the use and adaption of cable yarding technology on flat terrain. European manufacturers of cable yarding technology were interviewed about customer experience, particular challenges, adaptation potential, future potential and main hurdles for the expansion of cable yarding on flat terrain. Almost all manufacturers have received requests for flat-terrain yarding technology solutions, primarily from Germany. Temporal or permanent inaccessibility, regulatory or environmental reasons were the most frequent motivation for considering cable yarding technology. Installation was considered particularly challenging (clearance, stable anchoring). Potential adaptations included higher towers, artificial anchors, mechanized bunching before extraction and un-guyed yarder-systems. An artificial, highly mobile, self-anchoring tail spar was considered the most useful adaptation. While concerned about limited profitability and qualified labour shortage, most manufacturers demonstrated a positive or neutral view concerning the expansion of cable yarding on flat terrain. However, cable yarding is not considered to be cost-competitive wherever ground-based systems can be employed and cable yarding is not subsidized.