2-D delineation of individual citrus trees from UAV-based dense photogrammetric surface models

One of the challenges of remote sensing and computer vision lies in the three-dimensional (3-D) reconstruction of individual trees by using automated methods through very high-resolution (VHR) data sets. However, a successful and complete 3-D reconstruction relies on precise delineation of the trees in two dimensions. In this paper, we present an original approach to detect and delineate citrus trees using unmanned aerial vehicles based on photogrammetric digital surface models (DSMs). The symmetry of the citrus trees in a DSM is handled by an orientation-based radial symmetry transform which is computed in a unique way. Next, we propose an efficient strategy to accurately build influence regions of each tree, and then we delineate individual citrus trees through active contours by taking into account the influence region of each canopy. We also present two efficient strategies to filter out erroneously detected canopy regions without having any height thresholds. Experiments are carried out on eight test DSMs composed of different types of citrus orchards with varying densities and canopy sizes. Extensive comparisons to the state-of-the-art approaches reveal that our proposed approach provides superior detection and delineation performances through supporting a nice balance between precision and recall measures.     

Source Based Characterization and Pollution Profile of a Baker's Yeast Industry

Baker's yeast industry has significant effects on environment due to significant water consumption and high strength wastewater production. Effluents from baker's yeast industry are characterized by high concentrations of biological oxygen demand (BOD₅), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total dissolved solids (TDS), sulfate, and dark brown color. The aim of this study is to provide a detailed quantitative and qualitative identification and characterization of the wastewater sources from different processes of a baker's yeast industry. It is identified that the most polluted wastewater components of the facility are coming from rotary drum filter and evaporation process. However, the highest pollution loads is identified as tank and equipment cleaning effluent due to very high flow rate from this source. The efforts should be on the way to minimize the water usage for the tank and equipment cleaning process, and to recycle less polluted waste streams back to the process.     

Comparative Evaluation for Characterization of Produced Water Generated from Oil,Gas, and Oil–Gas Production Fields

A reliable wastewater characterization is a prerequisite for the selection of an acceptable treatment strategy for produced water which exhibits significant differences due to the varied kinds of wells, seasonal changes, and formation types. A complete characterization of produced water generated from oil, gas, and oil–gas fields in Turkey was performed based on seasonal and locational variations. The results showed that the produced water generated from oil field wells was highly polluted and wastewater volume was higher in comparison to gas and oil–gas field wells. Besides, the characterization of produced water was varying in a wide range based on seasonal and locational variations. Useful relationships were observed between chloride, sodium, bromide, and total dissolved solids concentrations. The results can be used in the design, operation, and optimization of wastewater treatment systems of petroleum and oil industries for future studies.     

Building a semantic based public transportation geoportal compliant with the INSPIRE transport network data theme

Interoperability is becoming essential for the today’s geographic information systems. Geographic information is usually available as datasets stored in databases and accessible via GIS. However, these information sources are increasingly heterogeneous and show differences in data formats, database schema and object concepts. To satisfy the increased demand for the use and sharing of geographic data in common applications, considering the heterogeneity and the methods to support interoperability are required by the GIS community. The implementation of Spatial Data Infrastructure (SDI) such as the European INSPIRE (Infrastructure for Spatial Information in the European Community) enables accessibility and the sharing of geographic data and interoperability among the systems. In addition to this, traditional GIS systems perform spatial queries using a keyword-based method. However, this approach remains incapable of fully expressing the users' needs due to a lack of geographic concepts (semantics) in the dataset. Different terms may refer to similar concepts, while the same terms may refer to different concepts. This causes semantic heterogeneity in the dataset. In this context, the most promising approach is the implementation of geospatial semantics by means of ontology in the geospatial dataset to overcome this kind of ambiguity. The aim of this research is to investigate the implementation of INSPIRE as a SDI standard and the use of Semantic Technology to empower the traditional GIS approach. In this regard, a public transportation geoportal has been developed for the experimental investigation which uses a revised sample transportation data complaint with the INSPIRE Transport Network Data Theme and a developed Transportation Ontology Domain, including concepts, relationships and individuals to provide a semantic spatial search.     

远震体波有限破裂过程反演敏感性测试及其在汶川地震上的应用

本文利用远震P和SH波反演得到2008年5月12日汶川大地震(M_W=7.9)的一系列有限破裂模型。使用一种基于小波变换的模拟退火非线性反演方法, 我们将主断层划分成若干个子断层, 在反演时同时确定每个子断层上的滑移量、 滑动角、 上升时间(rise time)以及平均破裂速度。我们首先根据一个假定的破裂模型生成理论地震图, 将该理论地震数据作为输入进行反演, 对该有限破裂反演方法进行了一系列测试, 以验证反演对断层倾角、 平均破裂速度、 最大破裂深度等参数的敏感性。然后我们采用4个不同倾角的断层面来对汶川地震远震体波记录进行反演。结果表明, 若对只在一个断层面上模拟该地震, 30°倾角是个较为合适的值。反演的结果还表明, 此次地震有两个主要的能量释放区域, 并且主断层面存在倾角变化的可能性。在将来的研究中, 可以结合GPS, InSAR测地学以及强震等数据, 来对强震的破裂过程做更细致的研究。     

A methodology to select seismic coefficients based on upper bound “Newmark” displacements using earthquake records from Turkey

Strong motion records taken during earthquakes in Turkey are used to calculate Newmark displacements in slopes. These displacements are then utilized in developing a novel displacement-based methodology to select the seismic coefficient which is used to calculate pseudostatic safety factor. In the first step of the study, calculated Newmark displacements are evaluated in three different categories which are as follows: using all data, using data for different earthquake magnitude (M) ranges with and without distance constraint and using data for different peak acceleration (a_max) ranges. For all categories, different equations are obtained to assign slope displacements as a function of the ratio of yield acceleration to peak acceleration. The results show that categorization of data is an important issue, because the displacements are earthquake magnitude and peak acceleration dependent. In the second step, equations obtained for different peak acceleration ranges are used to propose charts linking upper bound slope displacements (D), seismic coefficients (k_h) and pseudostatic safety factors (PSF), which are three important parameters of a pseudostatic approach. This enables the k_h values be chosen based on the allowable displacements, instead of the current applications based on judgement and expertise. The results show that k_h values for any allowable displacement should be based on anticipated a_max values, while use of high PSF values results in lower displacements. Extensive comparison with solutions from the literature is also made. The methodology is best suited for earthquake triggered shallow landslides in natural slopes, consisting of materials which do not lose strength during dynamic loading.     

Accuracy Assessment of Pleiades-1 Stereo/Tri-stereo Digital Surface Models: A Case-Study for Citrus Trees

In this study, we assess the quality of the digital surface model (DSM) generated from Pleiades-1 tri-stereo images which can potentially contribute to the detection of citrus trees in terms of height information. The methods tested on stereo/tri-stereo images are; (a) local methods (correlation-based and least squares method), (b) semi-global method (semi-global matching (SGM)), and (c) global method (SIFT-flow). DSMs of three sub-regions of Mersin area have been presented for each stereo/tri-stereo matching method; whereas for the SIFT-flow method, we have only depicted the parallax results. Numerical results reveal that the SGM forward-backward stereo combination which has the largest intersection angle provided the best results in 2 out of 3 test areas. However, the results confirm that none of the methods could reach the desired level of performance for the height estimation of citrus trees that can potentially guide the detection step.