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Wyszukujesz frazę "drewno sredniowymiarowe" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Utrata masy i zmiany gęstości średniowymiarowego surowca sosnowego pozyskanego i magazynowanego w okresie letnim
Weight loss and green density changes of Scots pine pulpwood harvested and stored during the summer
Autorzy:
Tomczak, A.
Wesołowski, P.
Jelonek, T.
Jakubowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/989611.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
pozyskiwanie drewna
lato
sosna zwyczajna
Pinus sylvestris
drewno sosnowe
drewno sredniowymiarowe
drewno swiezo sciete
magazynowanie
utrata masy drewna
gestosc drewna
scots pine
mass of logs
timber
freshly−cut trees
bark
wood moisture
Opis:
The study objectives included: i) determination of the mass and green density of pulpwood (wood+bark) and ii) comparison of the changes in these parameters during 14−day−long storage period. The experiment was conducted between 15 and 28 July 2014 and the material was taken from the 67 year−old Scots pine stand (Tuchola Forest District, northern Poland). Using the Urich method, 30 model trees were selected. After felling and delimbing, logs of 2.5 m length were cut, with diameter at the small end not less than 7 cm outside the bark. In total, 133 logs were harvested (mean diameter inside the bark at the thicker end – 13.1 cm, in the thinner end – 11.4 cm). After diameter measurements were taken, each log was weighed (total over bark volume equaled 4.69 m³, while total weight – 3955 kg). Mass measurement took place daily between 8 and 10 a.m. In Poland, the raw material is not recommended to be stored too long in summer, due to the possibility of its depreciation. Storage time should be as short as possible and not exceed 2 weeks. The mass of the 1 m³ of wood harvested from freshly−cut trees amounted to 844 kg. After 14 days it decreased to 814 kg (–3.5%). Differences were not statistically significant. Because the moisture content has the highest influence on mass, the rain and thereby an increase in the air humidity significantly reduce drying. Mass of 1 m³ of raw material was reduced to the day of rain by 2.9 kg (–0.35%) per day on average. After the occurrence of rainfall, between 10th and 14th day of storage the mean weight loss was 1.3 kg/m³ (–0.16%). The mean weight loss reached 30 kg/m³ in analyzed period. Generally two weeks storage is too short time to obtain a large weight loss. However, in this case of total mass of haulage vehicles together with their cargo may be a few hundred kilos smaller.
Źródło:
Sylwan; 2016, 160, 08; 619-626
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Możliwości ręcznego przemieszczania surowca krótkiego podczas pozyskania sosny, świerka, brzozy i buka w cięciach pielęgnacyjnych
Capabilities of manhandling small logs in commercial thinning in pine, spruce, beech, and birch stands
Autorzy:
Tomczak, A.
Grzywiński, W.
Jelonek, T.
Powiązania:
https://bibliotekanauki.pl/articles/986671.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany
ciecia pielegnacyjne
sosna
swierk
brzoza
buk
pozyskiwanie drewna
drewno krotkie
drewno sredniowymiarowe
masa drewna
reczne przemieszczanie surowca drzewnego
przemieszczanie ciezarow
health
musculoskeletal symptoms
loggers
weight of logs
green density
Opis:
The aim of this study was to measure the weight of timber obtained from freshly cut trees and compare it with the applicable legal provisions pertaining the capability of transporting heavy loads by hand and also to indicate a problem significant for the occupational safety and health protection of employees working at wood harvesting. In Poland, about 40 million m3 of timber is harvested annually. The logs, with small diameter and length, are prepared for forwarding by arranging them by employees in the so called ‘packages’, which are placed by the route of the machine that collects and transports them to the logging road. Manhandling of the logs is an activity requiring the greatest energy expenditure (over 30 kJ/min) in the process of tree harvesting. Furthermore, it is also one of the key factors, which may lead to the development of musculoskeletal disorders. Regulations existing in the Polish labour law regulate the permitted weight of transported loads depending on the activity duration. For loads transported single−handedly this is 30 kg for a permanent employer, whereas 50 kg for workers doing the job occasionally or temporarily (no more than 4 times per hour and no longer than 4 hours during workday). Logs heavier than 50 kg may be carried only collectively providing the requirements of the minimal length (0,75 m) of the log per one person are met. We produced 2,5 m long logs and weighted them with an accuracy of 0,1 kg. The analysis revealed that approximately 30% of logs weighed between 30 and 50 kg, which introduces limitations in the number of carried logs per one person within a single shift. However, about 10% of the pine, 15% of spruce, 12% of beech and 38% of birch logs were heavier than 50 kg which should prevent carrying them single−handedly. Unfortunately, collective preparation of timber for forwarding is not popular among workers due to reduction in output, and at the same time the lower salary. Even if log for forwarding is prepared by two labourers, they most often work separately. As a result, the limits of the weight carried single− handedly by labourer are notoriously violated and exceeded.
Źródło:
Sylwan; 2018, 162, 07; 531-538
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zrywka drewna średniowymiarowego w drzewostanach trzebieżowych przy użyciu ciągnika rolniczego z przyczepą nasiębierną
Timber extraction in thinned stands using agricultural tractor coupled with a trailer with a hydraulic crane
Autorzy:
Naskrent, B.
Polowy, K.
Grzywiński, W.
Sobczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/979600.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewostany sosnowe
drzewostany przedrebne
trzebiez pozna
pozyskiwanie drewna
drewno sredniowymiarowe
zrywka drewna
zrywka nasiebierna
fotografia dnia roboczego
struktura czasu pracy
timber extraction
time studies
forest trailer
working day photography
Opis:
The amount of timber extracted from Polish forests is expected to increase in near future. The most common equipment for timber extraction is an agricultural tractor with a trailer equipped with a hydraulic crane. The research was carried out in the Wymiarki Forest District (Regional Directorate of the State Forests in Zielona Góra) in the third (TP1) and fourth age class (TP2) in Scots pine stands, during extraction of timber from thinning. Extraction was carried out using BELARUS MTZ 1221.2 agricultural tractor with PALMS 120 forest trailer equipped with PALMS 700 hydraulic crane. The scope of the study was to conduct time studies of extraction process and to estimate the extraction productivity as well as time and fuel consumption. Working time was measured by stopwatch, while the forwarding distance was determined with measuring wheel. The exact number of logs in each load was established. Average volume of each log and each load was calculated. The dominant work time category was effective working time 74.78% (TP1) and 73.60% (TP2), while the prevailing work task was loading 56.82% (TP1) and 58.99% (TP2). In older stands, the extraction productivity was higher than in younger ones reaching 11.28 and 9.62 m3/h, respectively. Statistical analysis proved that extraction distance significantly affect productivity and time consumption. With increasing extraction distance productivity decreases and time consumption increases. Fuel consumption was exactly the same in younger and older stands (0.52 l/m3).
Źródło:
Sylwan; 2019, 163, 02; 121-129
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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