Semilogarithmic Research Articles

Generalized Multi-Hit Model of Radiation-Induced Cell Survival with a Closed-Form Solution: An Alternative Method for Determining Isoeffect Doses in Practical Radiotherapy.

The standard linear-quadratic (LQ) model is currently the preferred model for describing the ionizing radiation-induced cell survival curves and tissue responses. And the LQ model is also widely used to calculate isoeffect doses for comparing different fractionated schemes in clinical radiotherapy. Despite its ubiquity, because the actual dose-response curve may appear linear at high doses in the semilogarithmic plot, the application of the LQ model is greatly challenged in the high-dose region, while the dose employed in stereotactic body radiotherapy (SBRT) is often in this area. Alternatively, the biophysical models of radiation-induced effects with a linear-quadratic-linear (LQL) characteristic can well fit the dose-survival curve of cells in vitro. However, most of these LQL models are phenomenological and have not fully considered the biophysical mechanism of radiation-induced damage and repair, and the fitting quality decreases in some high-dose ranges. In this work, to provide an alternative model to describe the cell survival curves in high-dose ranges and predict the biologically effective dose (BED) for SBRT, we propose a novel generalized multi-hit model with a closed-form solution by considering an upper bound on the number of lethal damages induced by radiation that can be repaired in a cell. This model has a clear biophysical basis and a simple expression, and also has the LQL characteristic under low- and high-dose approximate conditions. The experimental data fitting indicated that compared to the standard LQ model and our previously generalized target model, the current model can better fit the radiation-induced cell survival curves in the high-dose ranges (P < 0.05). The current model parameters and parameter ratios were determined from the fits in different kinds of cell lines irradiated with various dose rates and linear energy transfer (LET), which indicates that the model parameters significantly depend on the dose rate and LET. Based on the current model, we derived two equivalence formulae for the BED calculations in the low- and high-dose ranges, and then calculated the BED for the clinical data of SBRT from 17 selected studies. The correlation analysis showed that there were significant linear correlations between the BED at isocenter and planning target volume (PTV) edge calculated by this model and the LQ model (R > 0.86, P < 0.001). In conclusion, the generalized multi-hit model proposed in this work can be used as an alternative tool to handle in vitro radiation-induced cell survival curves in high-dose ranges, and calculate the in vivo BED for comparing the dose fractionation schemes in clinical radiotherapy.

Structural and stellar-population properties versus bulge types in Sloan Digital Sky Survey central galaxies

ABSTRACT This paper studies pseudo-bulges (P-bulges) and classical bulges (C-bulges) in Sloan Digital Sky Survey (SDSS) central galaxies using the new bulge indicator ΔΣ1, which measures relative central stellar-mass surface density within 1 kpc. We compare ΔΣ1 to the established bulge-type indicator Δ〈μe〉 from Gadotti (2009) and show that classifying by ΔΣ1 agrees well with Δ〈μe〉. ΔΣ1 requires no bulge–disc decomposition and can be measured on SDSS images out to z = 0.07. Bulge types using it are mapped on to 20 different structural and stellar-population properties for 12 000 SDSS central galaxies with masses 10.0 &amp;lt; log M*/M⊙ &amp;lt; 10.4. New trends emerge from this large sample. Structural parameters show fairly linear log–log relations versus ΔΣ1 and Δ〈μe〉 with only moderate scatter, while stellar-population parameters show a highly non-linear ‘elbow’ in which specific star formation rate remains roughly flat with increasing central density and then falls rapidly at the elbow, where galaxies begin to quench. P-bulges occupy the low-density end of the horizontal arm of the elbow and are universally star forming, while C-bulges occupy the elbow and the vertical branch and exhibit a wide range of star formation rates at a fixed density. The non-linear relation between central density and star formation rate has been seen before, but this mapping on to bulge class is new. The wide range of star formation rates in C-bulges helps to explain why bulge classifications using different parameters have sometimes disagreed in the past. The elbow-shaped relation between density and stellar indices suggests that central structure and stellar populations evolve at different rates as galaxies begin to quench.

Demand Analysis of Termite Control Service in Jakarta

Termite is an economically important pest species in the pest control industry and considered as one of the urban pests. Although it had caused a great loss, only a few studies on termite control demand were found. This study attempted to identify determinants and build the econometric model of termite control demand in Jakarta. The findings are expected to give the pest control industry a better understanding of the pest control market. Two ad-hoc models, linear and double log models, were investigated using the Least Square Dummy Variable (LSDV) technique. The results showed that the double log model was found better than the linear model based on sign expectation and significance. The price of termite control service, building permits, price of structural metals and dummy variables for the large company were statistically significant determinants, whereas dummy variables for risk class were not. Termite control demand for medium and small companies was not significantly different, but both of them were significantly lower than demand for the large company. This study also found that the demand for termite control was elastic.Keywords: demand analysis, econometric modeling, pest control, termite control, urban pest

Nucleophilicity and solvent effects on the kinetics of 4-(pyren-1-yl)thiazol-2-amine interaction with 4,6-dinitrobenzofuroxan

A multistep synthesis of novel pyrene-based thiazole moiety been has been realized following some synthetic challenges and complications. The chemical structure of the synthesized compound has been established on the basis of both spectroscopic and analytical tools. Its nucleophilic reactivity with 4,6-dinitrobenzofuroxan (DNBF) has been successfully studied in solution. A kinetic study of the covalent electrophile/nucleophile combination of dinitrobenzofuroxan (DNBF, electrophile) and 4-(pyren-1-yl)thiazol-2-amine (nucleophile) resulting in the formation of the corresponding σ-adduct in solution is reported. The rate constant (k1) of the second-order relating to the CC bond forming step of this complexation process has been found to fit into the linear correlation log k = sN (N + E), thereby permitting the evaluation of the nucleophilicity parameter (N) of the 4-(pyren-1-yl)thiazol-2-amine. 4-(Pyren-1-yl)thiazol-2-amine has been subsequently ranked according to its reactivity profile on the general nucleophilicity scale developed recently by Mayr et al., leading to an interesting and direct comparison over a large domain of π-, σ-, and n-nucleophiles.

General modeling of karst spring hydrographs and development of a dimensionless karstic hydrograph concept

The response of a karstic-aquifer solution-cavity network subjected to a rainfall event leads to a hydrograph with rapidly increasing rising limb, but comparatively slower recession limb. In published studies, initial (early time) recession limb discharges have been modeled by consideration of the square root (nonlinear) response of the hydraulic head to karstic-sinkhole spring discharge. Late-time recession limb discharges are usually modelled by various mathematical methods such as exponential, quadratic and power functions, and straight line on semi-logarithmic plots. Hence, the recession-limb has been represented by different models, but without any model for the middle-time portion. In this paper, first, for early recession-limb times, a power model is developed by means of a convergence series. The result is compared with the literature models and it is observed that the presented model is significantly better than the previous ones. The literature models used the power 0.5, but this study uses 0.6 (a mathematical explanation for this adaptation is given elsewhere). The final portion of the recession limb is modelled by a straight line. Hence, the two-piece model used for the recession limb is examined. Then, a completely new approach is developed, where the whole karstic-sinkhole spring-discharge hydrograph is modelled mathematically by a single model through the logarithmic normal function. Finally, a dimensionless karstic-sinkhole spring-discharge hydrograph is suggested and its graphical and numerical forms are given for practical use by other researchers.

National characteristics of changes in the hazard of development of the COVID-19 coronavirus pandemic: mathematical modeling and statistical analysis

The article develops models and methods for calculating quantitative indicators of the response of the national state and society to the hazard of spreading COVID-19 coronavirus infection in different countries. There are used the concepts, models and methods in reliability theory to describe the development of the epidemiological situation with probability functions (possibilities) of no-failure operations (survival, health protection), probability density (distribution) of the failure (infection rates), integrated hazard of infection, failure rate (risk to take ill), acceptable risk, and manageability of the epidemic situation. Government control is carried out through pressure on the acceptable risk. Based on the results of statistical processing of data on the number of confirmed cases of the disease in different countries, a comparative analysis of the epidemic process in different national circumstances of the fight against the world pandemic was conducted. The reliability functions are based on a double interpretation of the equation of changes in the hazard measure over time and on the factors of development of the epidemic process, in particular, the age structure of the population is taken into account. The mathematical and statistical analyses are based on the exponential hazard equation, which is represented in a semi-logarithmic scale by a linear dependence on time. Nonlinear distortions are due to variations in the controlled value of acceptable risk and show national features of regulating the epidemic load on the population. The results obtained confirm the model's efficiency in clear terms of reliability theory and determine the direction of its improvement in the context of an ongoing global pandemic on the basis of newly emerging data and circumstances for a better understanding of the features of current processes across countries and continents.

COVID-19: Monitoring the propagation of the first waves of the pandemic

Introduction: A phenomenological approach is proposed to monitor the propagation of the first waves of the COVID-19 pandemic.Method: A large set of data collected during the first months of 2020 is compiled into a series of semi-logarithmic plots, for a selection of 32 countries from the five continents.Results: Three regimes are identified in the propagation of an epidemic wave: a pre-epidemic regime 1, an exponential-growth regime 2, and a resorption regime 3. A two-parameters scaling of the first-wave death variation reported in China is used to fit the first-wave data reported in other countries. Comparison is made between the propagation of the pandemic in different countries, which are classified into four groups, from Group A where the pandemic first waves were contained efficiently, to Group D where the pandemic first waves widely spread. All Asian countries considered here, where fast and efficient measures have been applied, are in Group A. Group D is composed of Western-European countries and the United States of America (USA), where late decisions and confused political communication (pandemic seriousness, protection masks, herd immunity, etc.) led to a large number of deaths.Discussion:The threat of resurging epidemic waves following a lift of lockdown measures is discussed. The results obtained in Asian countries from group A, as Hong Kong and South Korea, are highlighted, and the measures taken there are presented as examples that other countries may follow.

A new error upper bound formula for Gaussian integration in boundary integral equations

This paper proposes a new error upper bound formula for the Gaussian integration of the near-singular integral using the Boundary Element Method. First, this study found through numerical tests that the maximum relative error of the Gaussian integration has a downward concave shape but an approximately linear relationship with the relative distance, which is defined as the ratio of the distance from the source point to the element over the element length in a semi-logarithmic plot. Thus, the error upper bound can be defined as a line that closely approaches the computed error data points from the upper side. This line can be obtained by connecting two specified data points that are located outside, but very close to, the considered error range. Further research indicates that one parameter of the fitted line has a linear relationship with the number of Gaussian integration points and singularity orders and the other parameter can be treated as a constant, which together make the proposed Gaussian integration error upper bound formula widely applicable. Compared to the Lachat and Watson criterion, the proposed formula requires fewer integration points when the source point is very close to the element and thus serves to improve computational efficiency. The proposed formula also avoids calculation failure that can occur when using the Davies and Bu criterion. The numerical example results show that the proposed error upper bound formula can evaluate the integration accuracy well and improve computational efficiency when using an adaptive Gaussian integration method.

Correspondence.

To the Editor: We read with interest the recent article entitled “Pharmacokinetic study of intravitreal aflibercept in humans with neovascular age-related macular degeneration” by Do et al.1 With the exception of an earlier (uncited) abstract by two of the authors (D.V. Do and Q.D. Nguyen),2 there have been virtually no experimental data publicly available on the pharmacokinetics of aflibercept in human eyes. After carefully reviewing Table 1, we believe that the reported median concentrations contain multiple errors, and the half-life value of 11 days derived from them is incorrect. The erroneous median values apparently resulted from inclusion of the time points along with the concentrations. Using the five individual subjects' data reported in Table 1, we recalculated the median values for each time point and obtained the following: 0, 104, 65.9, 51.5, 42.0, 20.3, and 9.35 mg/L, shown in the semilogarithmic plot (Figure 1). Fitting these data to an exponential function (noncompartmental analysis, Certara Phoenix software v. 6.4) yielded a decay rate of 0.072 day−1 and a corresponding half-life of 9.6 days. Similarly, an noncompartmental analysis half-life of 9.5 days was obtained using the mean concentration data. Noncompartmental analysis of individual data showed high intersubject variability, with half-life estimates ranging from 3.7 days to 13.2 days (median and mean: 8.8 days). In aggregate, our analyses suggest that the correct ocular half-life of aflibercept in the human eye is circa 9 days, consistent with what Do and Nguyen2 reported in their earlier published abstract.Fig. 1.: Recalculated median concentrations versus time. Dashed line corresponds to an exponential function fit to the data, excluding the earliest time point. The decay rate of 0.072 days−1 corresponds to a half-life of 9.6 days.In view of the importance of the ocular half-life as a factor in determining the duration of biological and clinical effects after intravitreal injection,3 it is important to obtain and report accurate pharmacokinetic data on such ophthalmic products. Although the experimental study by Do et al1 seems to have been well designed and performed, the analysis and conclusions reported in the article are flawed. We hope the authors will also perform a reanalysis of their data and correct this.

QUANTIFYING EFFECTS OF CHANGING SPATIAL SCALE ON SPATIAL ENTROPY INDEX: USE OF FRACTAL DIMENSION

Abstract. Quantifying landscape heterogeneity and its organization at different scales is essential for understanding ecosystems and landscapes. Among hundreds of landscape metrics, entropy-related index represents an efficient tool to quantify and characterize landscape patterns. A recent development is Spatial Entropy index (Hs), and it has been validated as flexible and effective in landscape pattern analysis. However, the effects of changing spatial scale on Hs has not been quantified. This paper applies the fractal method to measure the spatial scale (grain size) sensitivity of Hs. Using the initial land-use data of Yanhe watershed, which is located in northwest of China, eleven different spatial scales were created in order to investigate the scale effects on Hs. A linear log–log regression model was then constructed based on the power law to calculate the coefficient of determination (COD) of the model and the fractal dimension (FD) of Hs. The result indicates that Spatial Entropy index shows a robust fractal feature, and it decreases as the spatial scale (or grain size) becomes lager in a moderate degree. In total, we believe that this study will help us to get a better understanding of Hs, and to facilitate further applications of this entropy-related index.

Estimation of the octanol–water distribution coefficient of acidic compounds by microemulsion electrokinetic chromatography

The feasibility of extending the determination of the lipophilicity of partially ionized acids (log Do/w) by microemulsion electrokinetic chromatography (MEEKC) is tested. Theoretical considerations predict that a linear log Do/w vs. log k correlation can be obtained only when the neutral and ionic forms of an acid follow the same correlation equation and the slope of the correlation is unity. In practice, since the lipophilicity of the neutral acid is much higher than that of the ionic form and the correlation slope is not very different from 1, the general linear correlation for neutral compounds can be applied across most of the ionization range of the acid.The linear correlation between log Po/w and log k of 20 neutral solutes (calibration curve) has been established and extended to 6 acids used as models, tested across their full ionization range. log Do/w-pH, and log k-pH profiles have been obtained for these 6 acids, and plotted log Do/w against log k for any acid at any degree of ionization. Furthermore, the log Do/w of the acids has been estimated from the calibration curve and log k-pH profile, and compared to values in the literature determined using reference methods such as the shake-flask one. Accurate values have been obtained using the MEEKC method when the acids are in their neutral form or partially ionized (ionization degree, α < 0.995). However, this parameter is overestimated when the acids are highly or fully ionized (α ≈ 1). Finally, in order to test the applicability of this method, we have applied the same procedure to estimate log Do/w at pH = 7.4 (blood physiological pH) of a set of 30 additional compounds (including partially and fully ionized acids). The results at this pH follow the same trend observed in the 6 model acids, and validate the application of the method for Do/w determination, except when α is very close to 1.

On the relative accuracy of power law analyses for uniaxial low stress steady state high homologous temperature deformation

If the mathematical operations are correct, uniaxial low stress, steady state high homologous temperature creep and steady state structural Superplasticity phenomena can be well described by a ‘power law’ that relates the applied stress to the strain rate of deformation (Padmanabhan et al., 2015). Isothermal dislocation creep, which exhibits no grain size dependence, displays a linear log strain rate – log stress relationship till there is a change in the rate controlling mechanism. In contrast, during grain-size dependent, isothermal steady state structural superplastic flow, even within narrow strain rate ranges the slope changes, notwithstanding the presence of the same rate controlling mechanism. In both the phenomena the stress exponent, n, decreases with increasing temperature even for a constant rate controlling mechanism (Padmanabhan, 1973). Four analytical methods, differing in details, are based on the power law equation, viz., a procedure used by experimental scientists, its improved variant, a method in vogue in rheology and a procedure due to Padmanabhan et al., 2015. By examining experimental data pertaining to many systems, it is demonstrated that the method of rheology does not follow the tenets of Dimensional Analysis and that the scatter in the predictions is the maximum for this case. The method of experimental scientists ignores the temperature dependence of the stress exponent and this leads to significant discrepancies between the measured and predicted properties. When mathematics is correct and the relevant physical situation is taken into account, the other two methods, i.e. the improved method of the experimental scientists and that of Padmanabhan et al., 2015, lead to similar results, but the latter analysis is more accurate because of its better normalizing procedure. It is also simpler. A missing detail in the earlier paper (Padmanabhan et al., 2015), viz., estimation of the grain-size exponent of the strain rate predicted for isothermal, steady state structural superplastic flow in terms of the Buckingham Pi Theorem is also furnished here.

PERKEMBANGAN INDUSTRI PENGOLAHAN DI KOTA BANJARMASIN

Ghiyats Maraya Rizki (2017) Development of Processing Industry In Banjarmasin City. Advisor: Dr. Hj. Ika Chandriyanti M.P.This study aims to examine the factors that affect the economic growth of the processing industry sector in the city of Banjarmasin. Independent variables in this research are Number of Business Unit of Processing Industry, Processing Industry Investment, and Processing Industry Worker, dependennya is economic growth of processing industry sector in Banjarmasin City.The data analyzed in this study is time series data obtained from the Central Bureau of Statistics Banjarmasin. Data analysis technique used is regression analysis by using semi log. Prior to the analysis, first classic assumption test to detect multikolineritas, heteroskedastisitas and autocorrelation.Research shows that only variable of business unit partially influence to economic growth of processing industry sector in Banjarmasin City. Together the variables of business unit, investment, and labor have influence to economic growth of processing industry sector in Banjarmasin City. Keywords: Economic Growth of Industrial Sector of Processing, Number of Business Unit of Processing Industry, Investment of Processing Industry, and Manpower of Processing Industry, Banjarmasin City.

Spatio‐temporal scaling of biodiversity in acoustic tropical bird communities

Automated analysis of acoustic communities is a rapidly emerging approach for the characterization and monitoring of biodiversity. To evaluate its utility, we should verify that such ‘bioacoustics’ can accurately detect ecological signal in spatiotemporal acoustic data. Targeting the ‘Biological Dynamics of Forest Fragments Project’ sites in Brazil, we ask: What is the relative contribution of the spatial, temporal and habitat dimension to variation in bird acoustic communities in a previously fragmented tropical rainforest? Does the functional diversity of bird communities scale similarly to space and time as does species diversity, when both are recorded by bioacoustics means? Overall, is the imprint of landscape fragmentation 30 years ago still audible in the present‐day soundscape? We sampled forty‐four sites in secondary forest and 107 sites in old‐growth forest, resulting in 11 000 h of audio recordings. We detected 60 bird species with satisfactory precision and recovered a linear log–log relation between sampling time and species diversity. Sites in primary forest host more species than sites in secondary forest, but the difference decreased with sampling time, as the slope was slightly higher in secondary than primary forests. Functional diversity, as exposed by vocalizing birds, accumulates faster than does species diversity. The similarity among local communities decreases with distance in both time and space, but stability in time is remarkably high: two acoustic samples from the same site one year (or more) apart prove more similar than two samples taken at the same time but from sites situated just a few hundred meters apart. These findings suggest that habitat modification can be heard as a long‐lasting imprint on the soundscape of regenerating habitats and identify soundscape–area and soundscape–time relations as a promising tool for biodiversity research, applied biomonitoring and restoration ecology.

The analysis of charge transport mechanism in molecular junctions based on current-voltage characteristics

We report here a theoretical model study of the current-voltage (I-V) characteristics of tunneling and hopping transport in molecular junctions. We found that the I-Vs of the two types of transport have very different shape characteristics. The I-V in tunneling transport is in near-linear relation at low bias, while is exponential for the hopping transport. The current in hopping transport thus can span a much wider range at semi-logarithm scale than tunneling transport, which can be used as an intuitive guide in analyzing the transport mechanism. The idea is supported by series of experimental studies reported before by Frisbie et al. where a clear I-V characteristic change can be seen when transport mechanism changed from tunneling to hopping. The two theoretical models were further used to fit the reported experimental I-V data, and we found that the transport mechanism obtained by the model is in consistence with the experimental conclusion. Moreover, our method also revealed the coexistence of two transports during the tunneling-to-hopping transition, and the contribution of the two channels to the current is bias dependent. Our research thus provides a new powerful theoretical method for the study of charge transport mechanism in molecular junctions.

Deep learning-assisted literature mining for in vitro radiosensitivity data

Background and purposeIntegrated analysis of existing radiosensitivity data obtained by the gold-standard clonogenic assay has the potential to improve our understanding of cancer cell radioresistance. However, extraction of radiosensitivity data from the literature is highly labor-intensive. To aid in this task, using deep convolutional neural networks (CNNs) and other computer technologies, we developed an analysis pipeline that extracts radiosensitivity data derived from clonogenic assays from the literature. Materials and methodsThree classifiers (C1–3) were developed to identify publications containing radiosensitivity data derived from clonogenic assays. C1 uses Faster Regions CNN with Inception Resnet v2 (fRCNN-IRv2), VGG-16, and Optical Character Recognition (OCR) to identify publications that contain semi-logarithmic graphs showing radiosensitivity data derived from clonogenic assays. C2 uses fRCNN-IRv2 and OCR to identify publications that contain bar graphs showing radiosensitivity data derived from clonogenic assays. C3 is a program that identifies publications containing keywords related to radiosensitivity data derived from clonogenic assays. A program (iSF2) was developed using Mask RCNN and OCR to extract surviving fraction after 2-Gy irradiation (SF2) as assessed by clonogenic assays, presented in semi-logarithmic graphs. The efficacy of C1–3 and iSF2 was tested using seven datasets (1805 and 222 publications in total, respectively). ResultsC1–3 yielded sensitivity of 91.2% ± 3.4% and specificity of 90.7% ± 3.6%. iSF2 returned SF2 values that were within 2.9% ± 2.6% of the SF2 values determined by radiation oncologists. ConclusionOur analysis pipeline is potentially useful to acquire radiosensitivity data derived from clonogenic assays from the literature.

Fitting the Generalized Target Model to Cell Survival Data of Proton Radiation Reveals Dose-Dependent RBE and Inspires an Alternative Method to Estimate RBE in High-Dose Regions.

The imprecise estimation of the relative biological effectiveness (RBE) of proton radiation has been one of the main challenges for further calculating the biologically effective dose in proton therapy. Since dose levels can greatly influence the proton RBE, the relationship between the two should be clarified first. In addition, since the dose-response curves are usually too complex to readily assess RBE in high-dose regions, a reliable and simple method is needed to predict the RBE of proton radiation accurately in clinically relevant doses. The standard linear-quadratic (LQ) model is widely used to determine the RBE of particles for clinical applications. However, there has been some debate over its use when modeling the cell survival curves in high-dose regions, since those survival curves usually show linear behavior in the semilogarithmic plot. By considering both cellular repair effects and indirect effects of radiation, we have proposed a generalized target model with linear-quadratic linear (LQL) characteristics. For the more accurate evaluation of proton RBE in radiotherapy, here we used this generalized target model to fit the cell survival data in V79 and C3H 10T1/2 cells exposed to proton radiation with different LETs. The fitting results show that the generalized target model works as well as the LQ model in general. Based on the fitting parameters of the generalized target model, the RBE of six given doses DT (RBET) could be calculated in the corresponding cell lines with different LETs. The results show that the RBET gradually decreases with increased dose in both cell types. In addition, inspired by the calculation method of the maximum values of RBE (RBEM) in the low-dose region, a novel method was proposed for estimating the RBE in the high-dose region (RBEH) based on the slope ratio of the dose-response curves in this region. Linear regression analysis indicated a significant linear correlation between the proposed RBEH and the RBET in high-dose regions, which suggests that the current method can be used as an alternative tool, which is both simple and robust, to estimate RBE in high-dose regions.

Characterization of laboratory-scale hydraulic fracturing for EGS

To investigate the impact of reservoir stimulation by hydraulic fracturing, a series of advanced lab-scale block tests were conducted with multiple measurement methods to characterize the fracture and to assess the operation and the performance of an enhanced or engineered geothermal system (EGS). The stimulation test samples were 330-mm cubic blocks of Sierra White granite with one injection well and four producers drilled into it. Acoustic emissions generated during the fracture initiation and propagation were monitored with twenty AE sensors mounted on all sides of the block to help characterize the fracture initiation and propagation process. The recorded AE signals were analyzed to obtain the event location and the failure mechanism. The localized AE events shows that due to the low viscosity of the fracturing fluid (water), the fracture propagated rapidly and took only about 1.4 s to reach near the block surface. During the fracturing phase, about 47 percent of the events were determined to be shear/mixed mode failure events, 28 percent tensile failure events, and 25 percent compressional failure events. Just after the simulation, a step-rate (constant flowrate) injection test was carried out to investigate the reservoir injectivity enhancement. During this phase additional compressional failure events were observed and the percentages of tensile failure and shear/mixed mode failure decreased. The dramatic increase of the injection rate with small increments of the injection pressure demonstrates the nonlinear response of the fracture to effective normal stress variation with much higher fracture opening increase during the low effective normal stress interval. Hydraulic fracturing tests under different stress levels show that more AE hits/events are recorded when the rock block is under higher applied stress. The reconstructed 3D fracture geometry shows good agreement with the AE monitoring results. After fracturing, a tracer test was carried out and the fracture aperture was estimated to be around 139 μm. The tracer recovery curve shows two linear portions of the tracer tail on a semi-log plot similar to that observed in some field data and predicted by numerical modeling. Laser scanning of the fracture surfaces indicates that the induced fracture has a rough surface with a joint roughness coefficient (JRC) of 12.98 and tortuosity of 1.10, both of which are slightly larger than that from the Brazilian test fracture on the same rock. The thin section and SEM observations show that the fracture follows the weak boundaries between the Quartz and Albite grains or the weak beddings in the grains.

Mathematical Functions to Model the Depth Distribution of Soil Organic Carbon in a Range of Soils from New South Wales, Australia under Different Land Uses

The nature of depth distribution of soil organic carbon (SOC) was examined in 85 soils across New South Wales with the working hypothesis that the depth distribution of SOC is controlled by processes that vary with depth in the profile. Mathematical functions were fitted to 85 profiles of SOC with SOC values at depth intervals typically of 0–5, 5–10, 10–20, 20–30, 30–40, 40–50, 50–60, 60–70, 70–80, 80–90 and 90–100 cm. The functions fitted included exponential functions of the form SOC = A exp (Bz); SOC = A + B exp (Cz) as well as two phase exponential functions of the form SOC = A + B exp (Cz) + D exp (Ez). Other functions fitted included functions where the depth was a power exponent or an inverse term in a function. The universally best-fitting function was the exponential function SOC = A + B exp (Cz). When fitted, the most successful function was the two-phase exponential, but in several cases this function could not be fitted because of the large number of terms in the function. Semi-log plots of log values of the SOC against soil depth were also fitted to detect changes in the mathematical relationships between SOC and soil depth. These were hypothesized to represent changes in dominant soil processes at various depths. The success of the exponential function with an added constant, the two-phase exponential functions, and the demonstration of different phases within the semi-log plots confirmed our hypothesis that different processes were operating at different depths to control the depth distributions of SOC, there being a surface component, and deeper soil component. Several SOC profiles demonstrated specific features that are potentially important for the management of SOC profiles in soils. Woodland and to lesser extent pasture soils had a definite near surface zone within the SOC profile, indicating the addition of surface materials and high rates of fine root turnover. This zone was much less evident under cropping.

Linear Regression Supporting Vector Machine and Hybrid LOG Filter-Based Image Restoration

Abstract The image restoration (IR) technique is a part of image processing to improve the quality of an image that is affected by noise and blur. Thus, IR is required to attain a better quality of image. In this paper, IR is performed using linear regression-based support vector machine (LR-SVM). This LR-SVM has two steps: training and testing. The training and testing stages have a distinct windowing process for extracting blocks from the images. The LR-SVM is trained through a block-by-block training sequence. The extracted block-by-block values of images are used to enhance the classification process of IR. In training, the imperfections on the image are easily identified by setting the target vectors as the original images. Then, the noisy image is given at LR-SVM testing, based on the original image restored from the dictionary. Finally, the image block from the testing stage is enhanced using the hybrid Laplacian of Gaussian (HLOG) filter. The denoising of the HLOG filter provides enhanced results by using block-by-block values. This proposed approach is named as LR-SVM-HLOG. A dataset used in this LR-SVM-HLOG method is the Berkeley Segmentation Database. The performance of LR-SVM-HLOG was analyzed as peak signal-to-noise ratio (PSNR) and structural similarity index. The PSNR values of the house and pepper image (color image) are 40.82 and 36.56 dB, respectively, which are higher compared to the inter- and intra-block sparse estimation method and block matching and three-dimensional filtering for color images at 20% noise.