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Issue Info: 
  • Year: 

    2016
  • Volume: 

    47
Measures: 
  • Views: 

    174
  • Downloads: 

    65
Abstract: 

WE EXTEND THE CONCEPT OF STRONGLY COMPACT AND SEMI COMPACT SPACES. A SPACE (X, T) IS SAID TO BE SEMI L-COMPACT (RESP. STRONGLY L-COMPACT) IF EVERY COVER OF X BY SEMI-OPEN (RESP.PREOPEN) SETS HAS A SUBCOVER OF X WHOSE CARDINALITY IS LESS THAN L, WHERE L IS THE LEAST INFINITE CARDINAL NUMBER WITH THIS PROPERTY. WE CHARACTERIZE SEMI L-COMPACT AND STRONGLY L-COMPACT SPACES.

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Issue Info: 
  • Year: 

    1394
  • Volume: 

    1
Measures: 
  • Views: 

    334
  • Downloads: 

    0
Abstract: 

لطفا برای مشاهده چکیده به متن کامل (PDF) مراجعه فرمایید.

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Issue Info: 
  • Year: 

    2016
  • Volume: 

    4
Measures: 
  • Views: 

    191
  • Downloads: 

    81
Keywords: 
Abstract: 

IN THIS TALK, SOME PROPERTIES OF LIPSCHIZ OPERATORS ARE STUDIED. CONDITIONS UNDER WHICH THE VECTOR-VALUED LIPSCHITZ ALGEBRA LIP (X, A) IS ISOMETRICALLY ISOMORPHISM TO LIP (X) ⊗ A ARE INVESTIGATED.

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Journal: 

GEOGRAPHICAL DATA

Issue Info: 
  • Year: 

    2019
  • Volume: 

    28
  • Issue: 

    111
  • Pages: 

    83-95
Measures: 
  • Citations: 

    0
  • Views: 

    505
  • Downloads: 

    0
Abstract: 

Extended Abstract Introduction Monitoring and assessment of the biosphere are two essential tasks at any scale. Based on this, forests play an important role in controlling the climate and the global carbon cycle. For this reason, biomass and consequently forest height are known as the key information for forest monitoring. In the recent decade, several studies have shown that the Synthetic Aperture RADAR (SAR) imaging systems in Compact Polarimetry (CP) mode can overcome the disadvantages of Full Polarimetric (FP) SAR imaging systems and provide a good performance in various remote sensing applications such as monitoring and managing the important natural resources like forests. In this regard, a novel technique named Polarimetric Interferometry SAR (PolInSAR) has been further considered as a powerful tool for forest height estimation. Materials & Methods In this research, the performance of the Compact PolInSAR (C-PolInSAR) data in Dual Circular Polarization (DCP) mode has been investigated in order to retrieve the forest height. For this reason, the common methods which are used for forest height estimation including Digital Elevation Model (DEM) differential method, coherence amplitude inversion, and phase & coherence inversion methods were applied and implemented on these data. In all of the aforementioned methods, LL+RR and LR polarizations were considered as the selected channels for estimating the volumetric and ground coherences, respectively. Then, the estimated coherences were considered as the input parameters for all of the mentioned methods. Results & Discussion To evaluate the performance and the efficiency of C-PolInSAR data in DCP mode, the results obtained from these data were compared with those obtained from Full PolInSAR (F-PolInSAR) data. The results obtained in this study in two datasets simulated from PolSARProSim software in both L and P bands showed that the C-PolInSAR data in DCP mode yielded a similar result compared to the F-PolInSAR data for forest height estimation (when the HH􀀍 VV polarization is adopted as the ground backscattering), because, in this case the LL+RR and the LR polarizations are equal to the HV and the HH􀀍 VV polarizations, respectively, particularly, the C-PolInSAR data in DCP mode yielded 􀀗 􀀖 ، پاییز 􀀏 􀀏 􀀏 ، شماره 􀀐 􀀖 دوره 􀀆 􀀇 لنامه علمی-پژوهشی اطلاعات جغرافیایی 􀂐 ف 12 / Scientific-Research Quarterly of Geographical Data (SEPEHR) Vo. 28, No. 111, Autumn 2019 0. 78 m and 0. 55 m improvements for forest height estimation in L and P bands, respectively. In addition, all of the employed methods provided better and closer results compared to the real forest height (i. e. 18 m) in L band compared to P band, because the electromagnetic (EM) waves have a more penetration into the canopy in L band compared to P band. Thus, the attenuation of these waves is low and consequently the height estimation is more accurate. Without considering the used bands, the DEM method provided the lowest precision compared to other methods, because the HV (or LL􀀍 RR) phase center can lie anywhere between half the tree height and top of the canopy. The exact location of this phase depends on two vegetation parameters which are the wave mean attenuation and the vertical canopy structure variations. In this case, the trees have very thin canopies, and consequently, the attenuation is small, but the phase center is high due to the structure. In other words, when the canopy extends over the entire forest height, then the phase center can be at half the true height for low density (low attenuation), through to the top of the canopy for dense vegetation (high attenuation). This ambiguity is inherent in single baseline methods, and in order to overcome this, model-based correction methods need to be employed. It was also observed that the coherence amplitude method is among the weak algorithms due to ignoring the phase and its sensitivity to the attenuation and structural variations but it can be used as a backup solution when other approaches fail. Finally, the phase and the coherence inversion method had better results than two aforementioned methods for the forest height estimation. In this method, selecting the factor 􀅎 􀀀 􀅏 is very important and it should be selected in a way to be strong towards the attenuation changes. In this study, 􀀀 􀀟 0. 4 was adopted to maintain the height error variations. Conclusion As the final result, the C-PolInSAR data can be an efficient strategy due to its performance, when the full polarimetric imaging systems are either limited or not available. Moreover, utilizing these data in long wavelengths (e. g. P band) is more appropriate due to the effect of the Faraday rotation on the transmitted polarization.

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    15
  • Issue: 

    11
  • Pages: 

    766-777
Measures: 
  • Citations: 

    1
  • Views: 

    405
  • Downloads: 

    0
Abstract: 

Background and Objectives Psychological flexibility is the main goal of acceptance and commitment treatment. However, an efficient tool is needed to measure it. Thus, the aim of this study was to investigate the psychometric properties of the Persian version of the Comprehensive assessment of Acceptance and Commitment Therapy processes (CompACT) Scale. Methods The statistical population of the present study included all people aged 18 to 60 years in the period from August to October 1400. The statistical sample of the study included 256 people who were selected by available sampling method through online call. In order to evaluate the convergent and divergent validity, the second version of the Acceptance and Practice Questionnaire (AAQ-II), the difficulty in emotion regulation scale (DERS-16) and the Depression, Anxiety and Stress Scale were used. The factor structure of the questionnaire was examined through confirmatory factor analysis. Reliability was performed using Cronbach’, s alpha method and retesting and analyzing the data with version 25 of SPSS software and version 8. 8 of LISREL. Results The results of confirmatory factor analysis, as in the original form, confirmed three factors: Openness to Experience, Behavioral Awareness and Valued Action. Also, Cronbach’, s alpha coefficient for the whole scale is 0. 89 and for the subscales of Openness to Experience, Behavioral Awareness and Valued Action were equal to 0. 91, 0. 88, 0. 85, respectively. In addition, the four-week retest coefficient for the whole questionnaire was 0. 80 and for the subscales of Openness to Experience, Behavioral Awareness and Valued Action were equal to 0. 89, 0. 78, 0. 79, respectively. Also, correlation coefficients indicated favorable convergent and discriminant validity of the questionnaire (P<0/001). Conclusion According to the obtained results, it can be said that the Comprehensive assessment of Acceptance and Commitment Therapy processes (CompACT) Scale is a reliable and valid scale for measuring psychological flexibility.

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Author(s): 

Alijani Aliakbar

Issue Info: 
  • Year: 

    2023
  • Volume: 

    4
  • Issue: 

    2
  • Pages: 

    21-24
Measures: 
  • Citations: 

    0
  • Views: 

    40
  • Downloads: 

    2
Abstract: 

The aim of this paper is to introduce and give preliminary investigation of ∂-partial-locally compact spaces. Locally compactness and ∂-partial-locally compactness are independent of each other. Every locally compact Hausdorff space is ∂-partial-locally compact. But the converse is not true even though it be Hausdorff. ∂-partial-locally compactness is a topological property. ∂-partial-locally compactness is not preserved by the product topology.

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Author(s): 

GHADER SARMAD | ESFAHANIAN V.

Issue Info: 
  • Year: 

    2007
  • Volume: 

    33
  • Issue: 

    1
  • Pages: 

    107-118
Measures: 
  • Citations: 

    0
  • Views: 

    1004
  • Downloads: 

    0
Abstract: 

This paper is devoted to assessing the accuracy of the compact and the super-compact finite difference methods for spatial differencing of the linearized shallow water equations. The second-order centered, the fourth-order centered, the fourth-order compact, the sixth-order compact and the sixth-order super-compact schemes are used to carry out the spatial differencing of the linearized shallow water equations on Arakawa's A and C grids. For the frequency and group velocity of linear inertia gravity waves on different numerical methods, the sixth-order super-compact method shows a substantial improvement on traditional centered and compact finite difference schemes.

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Writer: 

RIAZI A. | TAHMASBI N.

Issue Info: 
  • Year: 

    2009
  • Volume: 

    18
Measures: 
  • Views: 

    213
  • Downloads: 

    138
Abstract: 

In this paper, we give some results concerning the modular function of a locally compact group. Among other results we prove that if G is a locally compact non-unimodular topological group with the left Haar measure l and E is a Borel subset of G, then: (i) G has a proper non-trivial closed normal subgroup K such that EÇK and E−1ÇK have the same measure l.(ii) G has a non-empty non-cyclic open subsemigroup S such that if 0 6¹l (EÇS) <¥ then l (EÇS) > l ((EÇS)−1). If G is unimodular then E and its inverse have the same measure l.

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Author(s): 

SZEKELYHIDI L.

Issue Info: 
  • Year: 

    2007
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    221-226
Measures: 
  • Citations: 

    0
  • Views: 

    353
  • Downloads: 

    0
Abstract: 

At the Fourty-forth International Symposium on Functional Equations in 2006, Louisville, Kentucky, USA, T.M.K. Davison presented a talk under the title "D’Alembert’s functional equation on compact groups" in which he offered a solution method for this equation on any compact group. In this paper we offer another approach based on some very recent results on spectral synthesis, which method seems to be useful in the case of other equations.

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Author(s): 

TJANI M.

Issue Info: 
  • Year: 

    2003
  • Volume: 

    355
  • Issue: 

    11
  • Pages: 

    4683-4698
Measures: 
  • Citations: 

    1
  • Views: 

    114
  • Downloads: 

    0
Keywords: 
Abstract: 

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

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