Tadd — work time corresponding to add stage;. Tcc — work time corresponding to cc stage;. Tdepl — work time corresponding to depl stage;. Teff — actual work time corresponding to a complete succession of stages in tree felling;.

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Tadd — work time corresponding to add stage;. Tcc — work time corresponding to cc stage;. Tdepl — work time corresponding to depl stage;. Teff — actual work time corresponding to a complete succession of stages in tree felling;.

Tet — work time corresponding to et stage;. Tetpot — work time corresponding to etpot stage;. Tnc — work time corresponding to nc stage;. Tplm — work time corresponding to plm stage;. Trm — work time corresponding to rm stage;. Ttct — work time corresponding to tct stage;. The effects of logging on forest ecosystems quality highly depend on the duration of operations characteristic of this activity.

It is well-known and widely accepted that the longer the logging takes the higher the logging expenses become. This happens especially because of fixed expenses Conway and because beneficial effects decrease Ciubotaru as a result of the stress level increase, chiefly in the case of the forest ecosystem zoocenotic components Krause ; Radle ; Kight and Swaddle An accurate size of the work formation along with the amount and type of equipment are essential for meeting this objective.

The amount of necessary equipment depends on its efficiency and productivity under the work conditions characteristic of the felling area for which the planning is made. Time consumption Magagnotti and Spinelli or efficiency Richards et al. Productivity is influenced by the same factors and it represents the number of items produced in a time unit Kanawaty ; Richards et al.

The analysis of time consumption has been a constant preoccupation for researchers in the field of forestry. Samset dedicated an important part of his research career to studying ways of establishing work norms, improving productivity and production planning in silviculture Magagnotti and Spinelli Throughout the years, the research concerning time consumption focused especially on establishing a correlation between work efficiency and productivity accomplished with the help of various pieces of equipment and influenced by various factors characteristic of harvesting.

One field of research that enjoyed particular attention was the one regarding time consumption in chainsaw forest operations, namely felling operations, delimbing and cross-cutting from felling areas and the landing of felling areas. The time consumption in manual tree felling with a chainsaw is studied for various reasons: i the typical reason is to investigate the main factors affecting work productivity and to establish a model for cost calculations and salaries or payments; ii an accurate model may be used in different kinds of simulations that aim to find new, more efficient and environmental friendly felling techniques and to optimize felling operations for improving the existing chainsaws and education.

The research conducted so far emphasized the fact that in felling operations time consumption is mainly influenced by tree breast height diameter dbh Sobhani ; Kluender and Stokes ; Lortz et al. The dependency of felling time on tree breast height diameter is expressed by linear Samset ; Ghaffarian and Sobhani ; Uotila et al.

The complexity of the tree felling operation with the chainsaw led to the analysis of its every stage with respect to time consumption Nurminen et al. However, the research conducted is not homogeneous as far as the number and the significance of the felling operation stages are concerned and there are important differences in the approaches of various authors. Azarnoush and Fathi define six stages in the felling operation while Mousavi et al.

There is also a significant difference which occurs with regard to the content of the felling operation — Lortz et al. Among the numerous factors which influence time consumption in tree felling operations, the research conducted so far has taken into consideration the species Ghaffarian and Sobhani , the distance between trees and the harvested stand basal area Kluender and Stokes ; Wang et al.

Snow, and especially snow thickness, may increase time consumption. In the specific situation analysed in this paper, establishing productivity level involved measuring the volume of wood felled in a time unit. Productivity level is influenced by the same factors as time consumption, the two parameters being inversely proportional, respectively:. Mechanical saws are still an important equipment in tree felling Jourgholami et al.

The use of harvesters in harvestable resinous tree stands is limited by two important factors: tree diameter at stump level and ground slope Hiesel and Benjamin The motor-manual felling with chainsaws is still used even in Nordic countries, where it is favoured by small-scale operators, especially when dealing with biomass production Laitila et al.

Exceptions are forest owner operations and birch veneer log harvesting, where cutting is almost invariably performed manually with a chainsaw. A combined analysis of the effect of limiting factors tree diameter at stump level and ground slope emphasized the fact that, in the case of Romanian resinous tree stands, the use of cut-to-length method is recommended only for Under these circumstances, an analysis of work time structure and of productivity level in chainsaw operations constitutes an important preoccupation of sustainable harvesting management.

That is why, the main objective of this research is to establish models for time consumption and productivity level of Husqvarna mechanical chainsaw in the felling of resinous trees from mountainous areas. The models to be developed should be appropriate for giving accurate productivity estimates in resinous harvestable stands from mountainous areas as well as for cost calculations and different kinds of modelling and simulation purposes.

Research venue. Mixed spruce Picea abies L. The main characteristics of marked resinous trees and tree stands are presented in Table 1. A single team of workers, made up of a chainsaw operator and an assistant, was used. A representative team was selected formed by workers with an average level of representativeness Groover Four teams were selected with age and length of service close to the average values determined beforehand.

The team used for conducting this research was selected following the discussion with workplace leaders. The skilfulness of chainsaw operators expressed by the number of felled trees exceeded the recommended value of 8. The chainsaw Husqvarna cylinder displacement Work time structure in felling operations was analysed at the level of work shift, operations and stages. The research conducted for analysing the structure of the total worktime Fig.

The felling operation was divided into work stages according to the data in Table 2. To these, a series of activities which were not absolutely necessary form a technological point of view were added moving to and from the workplace at the beginning and ending of the schedule; meal, rest, needs, moving from one group of trees to another, organization; saw chain sharpening and chain tension; saw chain replacement and guide bar turning; cleaning the air filter; chainsaw fuelling with mixed fuel and oil for chain lubrication.

Their acceptance was justified in order to assure the conditions imposed by work safety norms, by the specific activities from forestry as well as by ergonomic and physiological requirements.

The detailed work time structure according to operations, stages and attendant activities is presented in Table 3. Time was measured in seconds Bureau International des Poidset Mesures , by using the continuous time study method. A stopwatch and a wrist watch were used to measure time by recording the inception and the ending of each operation, stage or activity during one shift.

The work shift was considered to begin at the moment when the team left the felling area landing and finish when returning to the same place. All measurements regarding work time were made by the same researcher. Dendrometric elements of trees and other samples analysed were measured by a second researcher in order not to disturb the work process. The same operation was measured and conducted in one work shift. Tree height was measured with a hypsometer, log length with a forest tape measure and stump diameter and dbh with a caliper.

Distances between felled trees were measured with a True Pulse telemeter. For the first tree the distance was measured at the felling area entrance. The time corresponding to walking the distance from the last tree felled in one shift to the edge of the felling area was included in the non-workplace time element NW.

Statistical analysis involved several steps. A first step consisted in the determination of sample size. The number of necessary measurements was established with the relation suggested by Kanawaty :. Values of p and q parameters were established by trial measurements. In Table 4 the minimum number calculated and the number of measurements made is presented.

A great number of measurements were made in order to normalize the distribution of the values measured and to minimize the Hawthorne effect. The second stage involved the determination of the main statistical indicators mean, standard error, median, standard deviation, variation coefficient of the working time corresponding to each work stage and to the variables measured in felling areas.

Based on the time consumed for each work stage, work time structure in felling trees was established. By using the total worktime, the number of trees and their volume, work productivity in felling trees with a mechanical chainsaw was determined. The next step was the identification of mathematical models which best express productivity variation. Further on, the correlations between working time corresponding to the felling stages and independent variables were identified by using the simple or multiple linear regressions.

A total of trees were felled in the two felling areas amounting to a volume of The total worktime TT necessary for felling trees in the two felling areas was of Work productivity in felling operations with Husqvarna mechanical chainsaw was of Productivity is strongly influenced by dbh.

In order to emphasize productivity dependence on dbh the average work time average Teff corresponding to a complete cycle according to diameter classes and without including delays ST — service time, NT — non-work time and NW — non-workplace time was taken into consideration. Thus, the main mathematical functions mentioned by literature in the field and used for estimating productivity in tree felling are presented in Fig. Felling productivity for different tree diameters at the breast height dbh without delay.

Differences in work time structure between the two plots occur mainly due to the time element NW , the moving time to and from the workplace at the beginning and the ending of the schedule being longer in S2.

Work time structure in tree felling according to stages is presented in Fig. It could be noticed that stages cc , et , depl and etpot prevail. Together they represent Time consumption in tree felling: Tdepl — work time corresponding to depl stage; Tplm — work time corresponding to plm stage; Tadd — work time corresponding to add stage; Tet — work time corresponding to et stage; Tetpot — work time corresponding to etpot stage; Trm — work time corresponding to rm stage; Tnc — work time corresponding to nc stage; Ttct — work time corresponding to tct stage; Tcc — work time corresponding to cc stage.

The main statistical indicators of worktime variation according to stages in tree felling and of operational variables measured in the two plots are presented in Table 6. This was of The correlation between the two variables is a very strong one 0. This is influenced by the presence or absence of obstacles seedlings, broken branches, stumps, etc around the felled tree and tree pruning as an expression of stand density. The time consumed for choosing the technical direction represents 4.

In the back-cutting the feller started the felling from the stem edge opposing the sink and made a single cut horizontally. Independent variables — breast height diameter dbh and stump diameter sd — have the greatest influence on work time in stages et and etpot. A strong correlation 0. A correlation of moderate intensity was identified between Tnc and sd 0. Weak correlations 0. Direct correlations of strong intensity 0.



Commission proposes a European Foundation Statute. There are clawificare factors which are not mentioned by literature in the field and which are related to work conditions from the felling area and the tree and tree stand characteristics. The chainsaw Husqvarna The effects of logging on forest ecosystems quality highly depend on the duration of operations characteristic of this activity. In the specific situation analysed in this paper, establishing productivity level involved measuring the volume of wood felled in a time unit.


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Asigurari de accidente 2. Prin urmare, nu se mentioneaza un plafon valoric peste care o achizitie se incadreaza in categoria mijloacelor fixe. Dar ispitele in sine nu sunt inca pacate si, daca le infrunta cu barbatie, ele pot fi de folos credinciosului, intarindu-l in virtute. Parintii sau persoanele care au copii in ingrijire sunt obligati sa ofere informatii, sfaturi si explicatii copiilor si sa le permita sa isi exprime propriile idei si pareri. De asemenea poti gasi ornamente flori de sapun care sunt o adevarata opera de arta si care, in acelasi timp, vor umple baia cu o aroma delicioasa si vor ingriji cu blandete pielea. Asigurari de mijloace de transport aerian 6.




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