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Issue Info: 
  • Year: 

    2015
  • Volume: 

    3
  • Issue: 

    5
  • Pages: 

    53-62
Measures: 
  • Citations: 

    0
  • Views: 

    632
  • Downloads: 

    0
Abstract: 

Woody Debris is structural and functional part on forest ecosystems and plays a key role in nutrition circulation and carbon storage in long time, tree regeneration and biodiversity conservation. For this reason, studies about investigation and determination of the amount, the method of measurement and spatial distribution of coarse woody are very important. To correct planning about coarse woody in Fandoghlou forests, at first febris we should measure the residues with a suitable statistical method. This study carried out with the aim of efficiency evaluation of line intersects sampling to estimate woody debris. To this, transect method applied based on probability, Huber, and Smalian approaches. Comparison the results of census and transect methods by using analysis of variance and Duncan test indicated that the transect method based on probability theory was the best.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2007
  • Volume: 

    60
  • Issue: 

    1
  • Pages: 

    103-114
Measures: 
  • Citations: 

    0
  • Views: 

    977
  • Downloads: 

    0
Abstract: 

In this study, the line intersect sampling method was employed in order to estimate residuals produced in northern forests. The parameters evaluated in this study were volume and weight per hectare. The results were compared based on the theory of probability, Huber formula and Smalian formula in order to find the best method. The study was carried out in three parcels with a total area of 107 hectares. 100% inventory was used to specify real indexes of the statistical population and then a linear sampling was conducted within a 100m*100m grid with transects with a length of 100 m in order to measure the volume and weight in a hectare. Based on the Tukey's method, the comparison test conducted with the real mean values and the mean values gathered in sampling showed there is no significant difference between real mean values and the mean values calculated in linear sampling based on the Huber formula. Furthermore, as regard the three methods of measurements, the linear sampling includes confidence limit. However, because of the inhomogeneity of the population and the lack of a plenty of sampling line, inventory errors in the linear sampling method is beyond the acceptable level (10%). Regarding the results, it was concluded that a linear sampling method based on the Huber formula is the best alternative to estimate the amount of residuals in forests.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    30
  • Issue: 

    2
  • Pages: 

    1-14
Measures: 
  • Citations: 

    0
  • Views: 

    48
  • Downloads: 

    32
Abstract: 

Background and Objectives:Studying the structure of the landscape based on the principles of ecology and the spatial indicators of the landscape as its components is considered a suitable tool for mapping and quantifying the spatial characteristics of each land use. Ecological functions, the structure of the landscape, and landscape patterns have undergone unwelcome changes due to the increasing expansion of human activities. Therefore, to monitor and control these changes, quantifying and studying the landscape is important. This study aims to quantify the landscape pattern of regions with different development levels using the line intersect sampling (LIS) method to estimate the metrics of the total length of the forest edge, and the point sampling method was conducted to estimate the metric of contagion. In this regard, the preserved region of Sefidkuh and the manipulated region of Qaleh Gol in Lorestan province were considered.Materials and Methods:For this purpose, we selected two 200-hectare areas from the two mentioned regions on Google Earth images and in a GIS environment. To perform the line intersect method, 16 transects with lengths of 100 and 200 m were fitted on the study area using systematically randomized directions. For the paired point sampling method, paired points with 100 and 200 m were systematically and randomly implemented on the selected images, and then metrics were calculated. The outcomes show that in both measured transects, the total length of the forest edge in the Qaleh Gol region is greater than in the Sefidkuh region, and the numerical value of the contagion metric in the Qaleh Gol region is less than in Sefidkuh. Also, the t-student method was applied to compare the regions with different line intersect lengths and paired point lengths. Then, spatial indices were calculated. The paired t-test was also used to compare the different distances in the two regions.Results:The findings show that there is more disturbance and fragmentation in Qaleh Gol. Moreover, the results indicate that the sampling methods used in this study are a suitable alternative for more detailed vegetation cover maps. The landscape patterns can be quantified by spending less cost and time and with higher accuracy. The obtained results can be used in planning and management at different levels (local, regional, and national), especially in areas with a high rate of change. Also, in this study, it was found that sampling methods are a suitable alternative for vegetation maps with many details. The results of the total length of the forest edge are also consistent with the results of the contagion estimation, and the Qaleh Gol area, which has less contagion, has a longer total length of the forest edge, indicating more destruction and fragmentation of this area compared to the less disturbed Sefidkuh area. Among the reasons for the disturbances in the Qaleh Gol area, we canmention the presence of artificial and man-made disturbances such as numerous villages, agricultural activities, horticulture, livestock grazing, and other rural activities. These have caused the thinning of the forest cover in the area. Conclusion:Linear intercept sampling (LIS) can be used to estimate the total edge length of forests, while paired-point sampling can be used to estimate the spatial coverage index. These methods can be effective alternatives to detailed vegetation cover maps for downsizing the pattern of land cover in different regions with varying degrees of development. They can also provide a more accurate comparison of land cover patterns with lower costs and in less time.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

TAVANKAR F. | BONYAD A.E.

Issue Info: 
  • Year: 

    2013
  • Volume: 

    20
  • Issue: 

    2
  • Pages: 

    95-109
Measures: 
  • Citations: 

    1
  • Views: 

    1164
  • Downloads: 

    0
Abstract: 

Minimizing of logging residuals has economic importance. In this research, volume and characteristics of logging residuals were studied in parcel 237 with 41ha from Asalem-Nav mountainous fagetum forest area. In this parcel silviculture method and logging system is single selection and assortment. The systematic sampling and line intersect method was used to estimate volume, weight, number and quality of logging residuals with twenty 100 m sample lines. Huber formula was used to measurement of each piece volume. Volume, weight and number of logging residues per hectare were estimated 3.6 m3, 2.5 ton and 233 pieces, respectively.Averages of volume, weight, length and middle diameters of pieces were estimated 0.02 m3, 15 kg, 1.5 m and 10 cm respectively. Roughly 65 percent volume of logging residue were recognized first class quality and without decay and knot. Ratios of logging residue volume to number of tree felling (R/N), log volume (R/L) and sum total of tree felling dbh (R/D) were estimated 0.58, 0.17 and 0.01. This amount of logging residuals is considerable and useable in wood industries. So export of those can have economic value.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

MUCIDA D. | CHEROUTRE H.

Issue Info: 
  • Year: 

    2007
  • Volume: 

    1
  • Issue: 

    3
  • Pages: 

    142-144
Measures: 
  • Citations: 

    1
  • Views: 

    193
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Journal: 

ACTA MEDICA IRANICA

Issue Info: 
  • Year: 

    2010
  • Volume: 

    48
  • Issue: 

    4
  • Pages: 

    231-233
Measures: 
  • Citations: 

    0
  • Views: 

    257
  • Downloads: 

    115
Abstract: 

Neonatal sepsis is an important cause of death and morbidity in newborns and is diagnosed by isolation of organism in blood culture. In several reports, reliability of blood cultures were done from umbilical catheters, have been demonstrated. The objective of the present study was to determine, whether an inde welling umbilical catheter, could be an alternative site for blood culture. In a prospective study over 6 months during 2006,141 paired blood cultures from 134 infant, were done simultaneously from peripheral site and umbilical catheter (mostly U. V. C), during the first four days of life. Majority of these infants were preterm and admitted to NICU for special care. these infants had indwelling umbilical line and had indication of sepsis workup. A total of 141 pairs of blood cultures were obtained from 134 infants. In 16 infants blood culture pairs were positive for one organism in both peripheral vein and umbilical site. 71. 6% of total cultures (n=11) pairs were negative in booths site. A total of 22 pairs were positive in one site only, with 5 positive from peripheral vein only and the other 17 from umblical site. Two pairs were positve in boths site with two different organisms. In over all 16 infant (11%) of blood were considered to be contaminated. Contamination rate were 2. 4% and 9. 2% for peripheral and umbilical catheter site. Contamination rate increased after 48 hours of age in umbilical catheter. The result showed that after 2 days contamination rate for blood culture taken from catheter line increased and specify decreased. We recommended that blood culture via umblical catheter in first 2 days in sick neonates with indwelling catheter can be a alternate site of blood culture sampelling.

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Journal: 

Issue Info: 
  • End Date: 

    آبان 1378
Measures: 
  • Citations: 

    6
  • Views: 

    255
  • Downloads: 

    0
Keywords: 
Abstract: 

در این طرح یک سیستم برق غیرقابل قطع که بصورت ON- LINE عمل می نماید طراحی و به صورت نیمه صنعتی ساخته شد. طراحی با اصول استانداردهای مورد نیاز برای مراکز صنعتی صورت گرفته به نحوی که قابلیت بکارگیری در این مراکز را داشته باشد. در مجموع سیستم شامل یک شارژر با ورودی سه فاز و خروجی 220 VDC به قدرت 15 kW، یک دستگاه اینورتر تکفاز با خروجی 50 Hz/ 220 VAC و قدرت 15 kVA در PF=0.8 و در ابعاد [2100 (H)×2400 (W)×750 (D)] mm آماده گردید.کارکرد دستگاه در دو حالت استاتیک و دینامیک تست گردید و نتایج حاصل مطلوب بوده است. نتایج کارکرد دستگاه مطابق با استاندارد IEC گویای کارکرد مناسب آن می باشد. عملکرد Static Switch و انتقال بار به برق شهر و اینورتر با زمان مطلوب و قابل قبول حاصل گردید و در کلیه حالات انتقال عملکرد مناسب بوده است. در مجموع با توجه به نحوه طراحی و پارامترهای انتخابی و از طرفی انتخاب عناصر مناسب در مدارها و رعایت استانداردهای مورد نیاز دستگاه دارای ضریب اطمینان بالا می باشد و قابلیت بکارگیری در محیطهای صنعتی از جمله صنایع مختلف نفت و برق را داراست.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2013
  • Volume: 

    66
  • Issue: 

    3
  • Pages: 

    267-276
Measures: 
  • Citations: 

    0
  • Views: 

    1011
  • Downloads: 

    0
Abstract: 

In this research, we tested biasedness of canopy cover and density estimation of forest trees and shrubs by the use of line sampling method. For this aim, locations and crown width of all trees and shrubs with crown width more than 10 cm in a 53 ha forest area in Ardal located in Chahar- Mahal and Bakhtiari Province were recorded. Then, 100 segments of line transect with various length (50, 100, 150, 200, 250, 300, 350 and 400 meter) were sampled, and this procedure was repeated 100 times. We used ANOVA to see if there is any significant differences between the estimated forest density and canopy cover with the different transect length. Results showed that, there is no statistical significant difference between various transects length for both variables. Also, as could be expected, by increasing the length of transects, the coefficient of variation was decreased and this decrease were negligible for transects longer than 200 m. This means no more precision could be achieved by more effort on measuring sample lines longer than 200 m. Analysis showed that the line transect sampling method is biased (over estimate) and the average relative bias were between 4-6 and 6-10 percent for tree density and crown coverage, respectively. Based on results, it can be claimed that, by considering the ease and speed of transect sampling method, the bias of estimates are negligible.

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Issue Info: 
  • Year: 

    1380
  • Volume: 

    10
Measures: 
  • Views: 

    2091
  • Downloads: 

    0
Abstract: 

یکی از معضلات ثبت سیگنالهای الکتروکاردیوگرام(ECG)  اضافه شدن نویز برق شهر، نویز سرگردانی خط مبنا و سیگنالEMG  به آن است. در این مقاله هدف ارزیابی روشهای مختلف حذف نویز سرگردانی خط مبنا است. این نویز ناشی از آرتیفکتهای تنفسی و حرکتی، جابجایی الکترودها و حرکت آنها روی بدن بیمار است و باعث ایجاد یک سطح شناور روی سیگنالECG  می شود. در اینجا برای حذف این نویز فیلترهای دیجیتال معمولی، فیلترهای وفقی، فیلترهای وفقی سری، فیلترهای وقفی ویولت و روشTSC بررسی و ارزیابی می شوند. نتایج بدست آمده نشان دهنده برتری روشهای وفقی سری و روشTSC نسبت به سایر روشهای به کار رفته است.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

Issue Info: 
  • Year: 

    2024
  • Volume: 

    33
  • Issue: 

    5
  • Pages: 

    558-563
Measures: 
  • Citations: 

    1
  • Views: 

    8
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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