Investigation of NDVI in relation to the growth phases of beech leaves in forest

The main objective of the science of phenology is to identify the time of the occurrence of conspicuous periodic phenomena in plants under the impact of climatic factors. The study of phonologic phenomena through visual observations and terrestrial studies and temperature registration using a thermo hydrometer in different altitudinal levels and using the satellite data of IRS1C/1D LISSIII in twelve 1-ha plots in pure beech stands in the altitudinal range of 500 to 1,200 m above the sea level from April to December was carried out in such a way that for each month, one image of sensor was allocated. The produced vegetation indices were matched with terrestrial observations of the phenology periods in each month in the beech plots. The results show that the increase of the altitude above the sea level functions like latitude and its most remarkable impact is the decreasing of the temperature and the shortening of growing season. The terrestrial observations carried out in the plots show that a sudden increase in the temperature leads to the faster growth and emergence of the leaves. The produced correlation coefficient between the temperature and the emergence of the leaves was (p?=?0.01) r?=?0.87. Moreover, the end of fall in the studied region has a direct and significant relation with temperature. The amount of correlation coefficient between the temperature and end of fall in the studied region is equal to (p?=?0.01) r?=?0.91. Normalized difference vegetation index (NDVI) is more related to the growth and nurturing of the leaves. The amount of NDVI during the growth of the leaves, completion of the leaves, and fall of the leaves is equal to 0.35, 0.6, and 0.25, respectively.     

An analysis of vegetation indices in relation to tree species diversity using by satellite data in the northern forests of Iran

Vegetation indices have been introduced for analyzing and assessing the status of quantitative and qualitative characteristics of vegetation using satellite images. However, choosing the best indices to be used in forest biodiversity and vegetation is one of the important problems faced by the users. The purpose of this research is to evaluate six vegetation indices in the analysis of tree species diversity in the northern forests of Iran. The present research uses LISS III sensor data from IRS-P6 satellite. Geometric rectification of images was performed using ground control points, and Chavez model was used for atmospheric correction of the data. The six spectral vegetation indices included NDVI, IPVI, Ashburn Vegetation Index (AVI), TVI, TTVI, and RVI. Shannon–Wiener species diversity index was used to analyze diversity, and the value of the index was calculated in each sample plot. Then, the spectral values of each sample plot were extracted from different bands. The best subset regression was used to analyze the relationship between species diversity and the related bands. The results obtained from the regression showed that polynomial equations under scrutiny as independent variables can assess tree and shrub species diversity better than other bands and compounds used (R ²?=?0.47). The obtained results also indicated a higher capacity in the case of the AVI index for estimating tree species diversity in the under study area.     

The use of three physico-chemical methods in the study of the organic matter associated with the sedimentary phosphorites in Djebel Onk Basin, Algeria

The study of the organic matter (OM) associated with the phosphate ore of Kef Essennoun deposit (Djebel Onk mining basin, Algeria) was with a view to determine the decomposition degree of the OM within the pellets and the matrix, and the conditions of diagenesis. The sedimentary phosphates of this deposit are constituted of sub-rounded, phosphate-rich grains (pellets) dispersed in a surrounding, much poorer than pellets in P, matrix (or gangue). The survey of the OM associated with both pellets and matrix used several types of analyses: scanning electron microscopy (SEM), scanning electron microscope with energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The results show the OM, dispersed approximately homogeneously, in the form of large flat particles, within the gangue and within the phosphatic pellets in the form of small particles. The O/C ratio showed that the OM is more oxidised in the matrix than within the pellets. The oxidation increased with the phosphatisation rate of the pellets and more with the carbonation rate of the matrix, but it decreased with the silicification degree in the siliceous carbonated matrix. Two major functional classes were distinguished within pellets: aliphatic and oxygenated ones, the latter being fundamentally present in humic OM. The presence and abundance of these humic compounds in pelletal phosphorites are known from the 1980s and considered as witnessing a formation of apatite in a strictly closed environment, inside the pellet.     

Ground roll attenuation using the S and x-f-k transforms

Ground roll, which is characterized by low frequency and high amplitude, is an old seismic data processing problem in land‐based seismic acquisition. Common techniques for ground roll attenuation are frequency filtering, f‐k or velocity filtering and a type of f‐k filtering based on the time‐offset windowed Fourier transform. These techniques assume that the seismic signal is stationary. In this study we utilized the S, x‐f‐k and t‐f‐k transforms as alternative methods to the Fourier transform. The S transform is a type of time‐frequency transform that provides frequency‐dependent resolution while maintaining a direct relationship with the Fourier spectrum. Application of a filter based on the S transform to land seismic shot records attenuates ground roll in a time‐frequency domain. The t‐f‐k and x‐f‐k transforms are approaches to localize the apparent velocity panel of a seismic record in time and offset domains, respectively. These transforms provide a convenient way to define offset or time‐varying reject zones on the separate f‐k panel at different offsets or times.     

Shake table study on an ordinary low‐rise building seismically isolated with SU‐FREIs (stable unbonded‐fiber reinforced elastomeric isolators)

This paper reports on the investigation of novel fiber reinforced elastomeric isolator (FREI) bearings, which do not have thick end plates, and are used in an unbonded application. Owing to the stable lateral load‐displacement response exhibited by the unbonded FREI bearings, the proposed bearings are referred to as stable unbonded (SU)‐FREIs. A shake table test program was conducted on a two‐story test‐structure having well‐defined elastic response characteristics. Compared with the results for the corresponding fixed base (FB) structure, the peak response values, distribution of lateral response throughout the height of the structure, and response time histories of the tested base isolated (BI) structure indicate that significantly improved response can be achieved. This study clearly indicates that SU‐FREI bearings can provide an effective seismic isolation system. Copyright © 2009 John Wiley & Sons, Ltd.     

绿洲耕地变化趋势及其驱动力——塔里木盆地南部策勒绿洲为例

以多年的野外实地调查资料和统计资料,分析了塔里木盆地南部策勒绿洲50年以来耕地面积变化的总体趋势、空间差异和驱动因子。基于GPS现场定位,应用GIS进行空间分析,通过建立多元回归模型,最终对该绿洲2010年和2020年的耕地数量进行了初步的预测。分析结果表明社会经济发展动态、农业科技进步和水土资源的限制等3大类因素是影响耕地数量的3个主成分,其结果将为进一步研究整个塔里木盆地南部绿洲耕地变化提供借鉴,为合理利用和保护耕地、为干旱区可持续发展提供科学依据。     

Imagery in the Presence of Turbulence Using Slit Aperture Telescope With Partial Adaptive Corrections

The objective of this communication is to study and totest numerically the concept of partial adaptive correction with arotating Slit Aperture Telescope (SAT). After a brief summary of theprinciple of image reconstruction with the rotating SAT operating withoutthe atmospheric turbulence, we describe the simulations of imagereconstruction when a partial atmospheric correction is performed in onedimension only, along the long axis of the rotating SAT. Thereconstruction algorithm performs the inversion of the Radon transform.The SAT can use a small adaptive optics system with far fewer actuatorsthan conventional two-dimensional devices, but a relatively high degree ofone-dimensional correction is needed to recover a satisfactorytwo-dimensional image. The effect of additive noise on the reconstructedimage is also investigated.     

Fourier analysis of the light changes of four Algol-type eclipsing variables

The aim of the present paper is to present the analysis of the light curves of four totally-eclipsing systems (BM Ori, VW Cyg, TW Dra, and RW Mon), using the automated Fourier techniques in the frequency-domain, developed recently by Kopal and his school at Manchester University.New Physical and geometrical elements for the above systems are derived.     

The Iraqi National Astronomical Observatory

Iraq is currently experiencing a praid cultural, scientific, and technical renaissance, and astronomy is a natural focus for the country's pride in the past achievements of the civilization which have flourished in Iraq. The current plans of the Space and Astronomy Research Center (SARC) include building a major observatory to work in the optical, IR and radio region of the spectrum.The core of the optical facility will be a 3.5 m optical telescope, together with 1.25 m telescope designed for efficient performance in the IR. These telescopes will be equipped with instruments for photographic, photometric and spectroscopic observations. A 30 m dish is also being built for millimeter/radio observations.SARC has selected an excellent observing site in the northern mountains of Iraq which has good seeing and clear dark skies. The sites selection was made with the collaboration of several leading astronomers and observatories from various countries.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984