Comparing the performance of multispectral vegetation indices and machine-learning algorithms for remote estimation of chlorophyll content: a case study in the Sundarbans mangrove forest

Optical vegetation indices (VIs) have been used to retrieve and assess biophysical variables from satellite reflectance data. These indices, however, also are sensitive to a number of confounding factors, such as canopy geometry, soil optical properties, and solar position. This suggests that VIs should be used cautiously for biophysical parameter estimation. Among biophysical variables, chlorophyll content is of particular importance as an indicator of photosynthetic activity. The goal of this study is to investigate the performance of multispectral optical VIs for chlorophyll content estimation in the world’s largest mangrove forest, the Sundarbans, and to compare these with machine-learning algorithms (MLAs). To this end, we have investigated the performance of 15 multispectral VIs and six state-of-the-art MLAs that are widely used for adaptive data fitting. The MLAs are Artificial Neural Networks (ANNs), Genetic Algorithm (GA), Gaussian Processes for Machine Learning (GPML), Kernel Ridge Regression (KRR), Locally Weighted Polynomials (LWP), and Multivariate Adaptive Regression Splines (MARS). We use an in situ data set of reflectance and chlorophyll measurements to develop and validate our models. Each MLA was evaluated 500 times with random partitions of training and validation data. Results showed that the weight optimization and term selection used within GA produce the most reliable chlorophyll content estimation. However, green normalized difference VI (GNDVI) is a simple and computationally efficient VI that produces results that are nearly as accurate as GA in terms of model fit and performance. Results also show that all methods except ANNs and MARS produce a quasi-linear relationship between spectral reflectance and chlorophyll content. Statistical transformations of GNDVI and chlorophyll content have the capability of further reducing model error.     

The Meta-Protocol framework

A communication protocol is a set of rules shared by two or more communicating parties on the sequence of operations and the format of messages to be exchanged. Standardization organizations define protocols in the form of recommendations (e.g., RFC) written in technical English, which requires a manual translation of the specification into the protocol implementation. This human translation is error-prone due in part to the ambiguities of natural language and in part due to the complexity of some protocols. To mitigate these problems, we divided the expression of a protocol specification into two parts. First, we designed an XML-based protocol specification language (XPSL) that allows for the high-level specification of a protocol—expressed as a Finite State Machine (FSM)—using Component-Based Software Engineering (CBSE) principles. Then, the components required by the protocol are specified in any suitable technical language (formal or informal). In addition, we developed the multi-layer Meta-Protocol framework, which allows for on-the-fly protocol discovery and negotiation, distribution of protocol specifications and components, and automatic protocol implementation in any programming language.     

Effect of different surface shapes formed by femtosecond laser on zirconia-resin cement shear bond strength

Objective: The purpose of this study was to evaluate the effect of different surface shapes formed by femtosecond (FS) laser on zirconia (Y-TZP)-resin cement shear bond strength (SBS). Background data: All ceramic restoration is used as an alternative to metal-ceramic restorations, due to its better aesthetics, strength, and toughness properties. However, bond strength of restoration to tooth and other materials is effective to long term success of the restoration, and to achieve it surface treatment is required on ceramic surface. Materials and methods: Forty square-shaped zirconia samples were prepared and assigned to four groups of 10. The details of the groups are as follows: Group A, square-shaped recessed surface; Group B, square-shaped projection surface; Group C, circular-shaped recessed surface; Group D, circular-shaped projection surface. The SBSs values were performed with a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed statistically using analysis of variance (ANOVA) and Tukey HSD multiple comparisons tests. Results: The one-way ANOVA results on SBSs of the zirconia material bonded with resin cement revealed significant differences among the groups (p < 0.05). The Tukey HSD test results revealed that Group B and D had significantly higher SBS values than other groups (p < 0.05), but there were no significant differences between each other (p > 0.05). Additionally, Group A and C had significantly lower values than other groups (p < 0.05). Conclusions: Different surface shapes formed by FS laser provided a significant increase in SBSs. The SBS values of projection surfaces of circular and square-shapes are greater than that of recessed surfaces of circular and square-shapes.     

Equilibrium and pre-equilibrium calculations of neutron production in medium–heavy targets irradiated by protons up to 100 MeV

In this study, by using equilibrium and pre-equilibrium reaction mechanisms, the (p,xn) cross-sections of the spallation neutron target nuclei ^50,52,53,54Cr and ^63,65Cu were investigated for incident proton energies up to 100 MeV. The excitation functions for pre-equilibrium reaction mechanisms were calculated by using a hybrid model, a geometry dependent hybrid model, the full exciton model and the cascade exciton model. Equilibrium effects were calculated according to the Weisskopf–Ewing model. The calculation results were also compared with the measurements in literature.     

Parametric estimation of time-varying components using orthogonal bases

For nonstationary processes, classical frequency estimation methods are incapable of describing and showing the information embedded in the process. That is, because the statistical characteristics (SC) of the nonstationary processes are changing with time, estimation methods based on the stationarity assumption do not reflect this variation. Therefore, the idea of the time-frequency (TF) distribution has been introduced in the literature. Different methods for estimating the TF distribution (TFD) of a nonstationary process have also been proposed in the literature. All of these methods, however, depend on the degree of nonstationarity (DON) of the process, which, although of utmost importance, has not been yet addressed in the literature. In this paper, an algorithm for estimating the time-varying components (TVCs), and hence the TF kernel, of a non-stationary process by using orthogonal projection is proposed. The process is carried out by projecting each component of the process onto an expanding orthogonal basis. The TF kernel is then estimated with an order based on the dimensionality of the expanding orthogonal basis. Some experimental results are presented when the process has either single or multiple TVCs. This revised version was published online in June 2006 with corrections to the Cover Date.     

A cellular automata model for circular movements of pedestrians during Tawaf

Masjid Al-Haram in Saudi Arabia is one of the most crowded pilgrimage locations in the world. More than two million pilgrims gather in Saudi Arabia annually during the Hajj season, and it is compulsory for them to perform a series of actions in the mosque. In the court area, pilgrims perform one of the most important rituals of Hajj, called Tawaf, which consists of seven laps of circular movement around the Kaabah, which is situated in the centre of the court. After the Tawaf, pilgrims pray in the court and leave from one of several doors. In this paper, we present a cellular automata model for the simulation of the pilgrims’ circular Tawaf movement. We also use a discrete-event model to simulate the actions and behaviours of the pilgrims. The proposed models are used in a software platform to simulate the actions and movements of pilgrims in the area. We then present an example application of the model in predicting whether specific changes to the architecture could increase the throughput of the system.     

Chemical desulfurization of petroleum fractions for ultra-low sulfur fuels

An improved desulfurization process for removing sulfur from hydro treated diesel oil based on the oxidation of thiophenic type sulfur-containing compounds with H₂O₂ and acetic acid (AcOH) using H₂SO₄ as catalyst has been studied. The experimental results show that the sulfone content in the oxidation product increased rapidly with an increase in acetic acid and sulfuric acid ratios from 1:0 to 2:1 mole ratios. The maximum DBT conversion (wt.%) was at 2:1 mole ratio of acetic acid/sulfuric acid. This oxidation process is found to be capable of removing up to 90% of the sulfur compounds in hydro treated real fuels and can provide an alternative way to meet the future sulfur environmental requirements.     

Structure,Protein Interactions and In Vitro Protease Accessibility of Extruded and Pressurized Full-Fat Soybean Flakes

The objectives of the present study were to determine how extrusion (barrel temperature of 100 °C) and high-pressure processing (HPP, 200 and 500 MPa, 15 min, 25 °C) of full-fat soybean flakes (FFSF) modified the structure of soybean cotyledon cells, the protein interactions and the in vitro protease accessibility. Cellular disruption of the cotyledon cells was only observed for extruded FFSF. Extrusion and HPP at 500 MPa favored formation of insoluble protein aggregates, in which oil was entrapped. High pressure size exclusion chromatography (HPSEC) and extraction methods using buffers containing SDS and 2-mercaptoethanol suggested that noncovalent interactions were the main forces in protein aggregate formation during HPP 500 MPa and extrusion. Intermolecular cross-linking by disulfide bonding was also involved in insoluble aggregates, but at a lesser extent than noncovalent interactions. Extrusion and HPP 500-MPa treatment enhanced the proteolytic attack, while treatment at 200 MPa had no impact. Drastic changes in the peptide profile of the extracted proteins were, however, only observed for the enzyme-treated 500-MPa FFSF. Optimal oil and protein extraction yields required cellular disruption of cotyledon cells and hydrolysis of protein aggregates, which were obtained with enzyme-assisted aqueous extraction of extruded FFSF.     

Impacts of impregnation with Imersol-Aqua on the compression strength of some solid wood materials

The aim of this study was to investigate the effects of impregnation with Imersol-Aqua on the compression strength of some solid wood materials. For this aim, Oriental beech (Fagus orientalis Lipsky), European oak (Quercus petrea Liebl.), Scotch pine (Pinus sylvestris Lipsky), Uludag fir (Abies Bornmülleriana Mattf.), Oriental spruce (Picea orientalis Lipsky) and Lombardy poplar (Populus nigra Lipsky) wood samples were prepared according to TS 2595 and impregnated with Imersol-Aqua, commonly being used in construction wood materials by the method of short, medium and long-term of dipping according to ASTM D 1413 and producers’ definition. After the impregnation process, compression strength was measured according to TS 2595. Consequently, among the non-impregnated wood materials, the highest compression strength was obtained in beech and pine samples. Compression strength at this situation from the highest to lowest can be enumerated beech, pine, oak, spruce, fir and poplar. With regard to the impregnation period, the sequence form the highest to lowest was as long-term, medium-term and short-term dipping. In the interaction of wood material and impregnation period, the highest compression strength values were obtained in Scotch pine (71.220 N mm⁻²) impregnated with long-term dipping method whereas the lowest in Lombardy poplar (35.710 N mm⁻²) impregnated with short-term dipping method.

In consequence, in the massive constructions and furniture elements that the compression strength after the impregnation is of great concern, long-term impregnation of solid wood material could be recommended.