Minimum Coefficient Of Determination Research Articles

Length-weight relationships and growth pattern of Macrobrachium malcolmsonii (H. Milne-Edwards, 1844) from the river Old Brahmaputra, Bangladesh

Study of biological parameters of a species is important for its sustainable management. The length-weight relationships and growth patterns of Macrobrachium malcolmsonii (H. Milne-Edwards, 1844), collected from the river Old Brahmaputra in Bangladesh, were determined in this study based on 359 specimens (carapace length, CL: 11–90 mm; body weight, BW: 0.2–54.4 g) including 308 male and 351 female individuals. For both sexes, intercepts, slopes, and coefficients of determinations of regression analyses between CL and BW varied monthly. The lowest values of intercept (–11.51 and –11.65 for male and female respectively) was recorded in October whereas the highest values were recorded in January for male (–7.01) and March for female (–8.26 for female). The minimum coefficient of determination was 0.784 (for male) and 0.801 (for female) whereas the maximum coefficient of determination was recorded 0.971 (for male) and 0.970 (for female). For male, the b value at 95% Cl revealed that the growth in March, June, July, September and February were isometric and in April, May, October, November and January were allometric. Whereas for female, the growth in March, April, June, July, November, January and February were isometric and was allometric in May, September and October.

Remote Sensing for Plant Water Content Monitoring: A Review

This paper reviews the different remote sensing techniques found in the literature to monitor plant water status, allowing farmers to control the irrigation management and to avoid unnecessary periods of water shortage and a needless waste of valuable water. The scope of this paper covers a broad range of 77 references published between the years 1981 and 2021 and collected from different search web sites, especially Scopus. Among them, 74 references are research papers and the remaining three are review papers. The different collected approaches have been categorized according to the part of the plant subjected to measurement, that is, soil (12.2%), canopy (33.8%), leaves (35.1%) or trunk (18.9%). In addition to a brief summary of each study, the main monitoring technologies have been analyzed in this review. Concerning the presentation of the data, different results have been obtained. According to the year of publication, the number of published papers has increased exponentially over time, mainly due to the technological development over the last decades. The most common sensor is the radiometer, which is employed in 15 papers (20.3%), followed by continuous-wave (CW) spectroscopy (12.2%), camera (10.8%) and THz time-domain spectroscopy (TDS) (10.8%). Excluding two studies, the minimum coefficient of determination (R2) obtained in the references of this review is 0.64. This indicates the high degree of correlation between the estimated and measured data for the different technologies and monitoring methods. The five most frequent water indicators of this study are: normalized difference vegetation index (NDVI) (12.2%), backscattering coefficients (10.8%), spectral reflectance (8.1%), reflection coefficient (8.1%) and dielectric constant (8.1%).

Surface eddy fluxes and friction velocity estimates taking measurements at the canopy top

Agricultural engineers, crop physiologists and hydrologists are often forced to deploy instrumentation close to the canopy top to estimate surface eddy fluxes. This is a widely recognized problem either at farm-level or research-level. The eddy covariance (EC) method is grounded on hypothesis, simplifications and relationships valid in the inertial sublayer and alternative methods may require either calibration or inputs that are not commonly available. The present study enables a method that combines similarity, transilient and surface renewal theories in conjunction with the analysis of small eddies (Surface renewal of small eddies, SRSE, method) to estimate the friction velocity and surface fluxes of different scalars (sensible heat, latent heat and carbon dioxide) taking measurements at the canopy top. SRSE minimizes estimation of canopy parameters (only the zero-plane displacement is involved), allows implementing a primary flux quality control and to guide instrumentation deployment. For a mature maize crop, SRSE and EC surface energy balances indicated that EC was slightly more reliable than SRSE during daytime. For unstable cases, the normalized mean absolute error (MAE) to the available net surface energy (ANSE), MAE/ANSE, obtained by the EC and SRSE methods were 9% and 13 %, respectively. For stable cases during the day, 10 % and 11 %, respectively. For stable cases at night SRSE performed better than EC, MAE/ANSE were 23 % and 16 %, respectively. Regardless of the half-hourly eddy flux (including the friction velocity), the EC and SRSE were highly correlated (the minimum coefficient of determination was 0.91) and, in average (for all data) flux of scalars nearly matched including water-use-efficiency. To avoid acquisition of expensive and stringent instrumentation, the closure of the surface energy balance equation was forced to derive affordable approaches to estimate the latent heat flux for different stability cases.

Growth and Sex Ratio of Octopus Paroctopus Digueti (Perrier & Rochebrune, 1894) in a Wild Population

Abstract In Mexico, studies of octopus Paroctopus digueti are scarce, thus the objective of this research is to evaluate some of its biological aspects in Ohuira Bay, Ahome, Sinaloa, Mexico. From autumn 2016 to autumn 2017, a total of 217 organisms of P. digueti were collected, from which 166 were females, 31 ovigerous females and 20 males. The lengths of the mantle (ML), tentacles or arms (AL) and total length (TL) were recorded as well as the total weight (TW) of each organism. The software FiSAT II was used to obtain the growth parameters by mediating seasonal size frequencies. Considering both sexes, the average registered mantle length was 40.31±2.5 mm. For the analysis of ML-TL y ML-AL, the data were adjusted to a linear-type model. For the relationship between ML-TL, the minimum determination coefficient was observed during spring R2 = 0.335, and the highest was registered in winter R2 = 0.6452. With regards to the allometry coefficient (b), it was different among the 4 climatic seasons. The theoretical ML growth curve showed both sexes of ML∞= 73.50 mm, K = 1.30 year−1 and t0= 0.10. The estimated values from the growth equation revealed faster growth (ML∞= 63 mm) within the 1.2 years of their lives, reaching a maximum length at 2.5 years of age. The total weight growth curve of P. digueti octopus was formed by an exponential first stage up to six months and the second logarithmic stage from seven months to approximately 1.8 years. In the summer there were slightly lower coefficients and percentages of instantaneous growth coefficients (IGC) for the lengths and total weight of octopus P. digueti. The highest Fulton’s condition index (k) was recorded in winter. The sex ratio was significant in a proportion of 9.85 F:1 M.

Study on a Nonlinear Dynamic Model and Its Parameters Determination Method for Half-Sine Programmer

A nonlinear dynamic model for describing shock response of half-sine programmer in shock test is constructed, in which many important factors in half-sine programmer such as size, hard nonlinearity, damping and initial impact velocity are considered, based on the damped Duffing equation, and the empirical static stiffness and shock stiffness calculation formulas of cylindrical rubber isolator. The shock pulse of half-sine programmer is measured and calculated by using shock test machine and Runge-Kutta method. Taking the minimum determination coefficient between the calculated and the measured shock pulse as the optimization objective, the parameters in the present model are determined by using quantum genetic algorithm (QGA), and meanwhile the extreme capacity in the present model for describing the dynamic behavior of half-sine programmer under shock excitations can also be verified. Experiments were implemented with drop shock test machine. The experimental results show that the present model is precise and efficient, and the prediction errors of pulse peaks and pulse widths were all below 5%, the waveform fitting errors between the calculated and the measured pulses are all less than 15%. The present results are helpful for designing the half-sine programmer.

Research and Implementation of ε-SVR Training Method Based on FPGA

Online training of Support Vector Regression (SVR) in the field of machine learning is a computationally complex algorithm. Due to the need for multiple iterative processing in training, SVR training is usually implemented on computer, and the existing training methods cannot be directly implemented on Field-Programmable Gate Array (FPGA), which restricts the application range. This paper reconstructs the training framework and implementation without precision loss to reduce the total latency required for matrix update, reducing time consumption by 90%. A general ε-SVR training system with low latency is implemented on Zynq platform. Taking the regression of samples in two-dimensional as an example, the maximum acceleration ratio is 27.014× compared with microcontroller platform and the energy consumption is 12.449% of microcontroller. From the experiments for the University of California, Riverside (UCR) time series data set. The regression results obtain excellent regression effects. The minimum coefficient of determination is 0.996, and running time is less than 30 ms, which can meet the requirements of different applications for real-time regression.

Determination of Paraquat and Diquat in Potato by Liquid Chromatography/Tandem Mass Spectrometer

A high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of paraquat and diquat in potatoes using a reversed-phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity Q1 column. Five grams of sample was shaken with fifteen milliliters of 1:1 MeOH: 0.1 N HCl for 10 min at room temperature and heated for 15 min at 80°C. After centrifugation, the supernatant was passed through an Oasis HLB SPE to retain suspended particulates and non-polar interferences. The sample was directly injected and analyzed for 10 min by LC-MS/MS with no sample concentration. Two multiple reaction monitoring (MRM) channels were monitored in the method for each target compound to achieve true positive identification. Two internal standards corresponding to each analyte were used to counter matrix suppression effect. Linearity of the detector response with a minimum coefficient of determination (r2) of more than 0.997 was demonstrated in the range from 2 to 250 ng/mL for each analyte using matrix-matched standard. The average recovery for all analytes at 10, 25, 100, and 500 ng/g (n$=$5) are between 87-106% with a relative standard deviation of less than 12%.https://doi.org/10.21423/jrs-v05n01p001 (DOI assigned 4/17/2019)

Direct determination of glyphosate, glufosinate, and AMPA in soybean and corn by liquid chromatography/tandem mass spectrometry.

Glyphosate, glufosinate, and aminomethylphosphonic acid (AMPA) are amphoteric, low mass, high water soluble, and do not have chromophore. They are very difficult to be retained on a reversed phase HPLC and detected by UV or fluorescence detectors. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed to determine these analytes in soybean and corn using a reversed phase with weak anion-exchange and cation-exchange mixed-mode Acclaim™ Trinity™ Q1 column. The sample was shaken with water containing ethylenediaminetetraacetic acid disodium salt (Na2EDTA) and acetic acid for 10min to precipitate protein and extract the analytes into the solution. The supernatant was passed thru an Oasis HLB SPE to retain suspended particulates and non-polar interferences. The sample was directly injected and analyzed in 6min by LC-MS/MS with no sample concentration or derivatization steps. Three isotopically labeled internal standards corresponding to each analyte were used to counter matrix suppression effect. Linearity of the detector response with a minimum coefficient of determination (R (2)) of more than 0.995 was demonstrated in the range of 10 to 1000ng/mL for each analyte. Accuracy (recovery %) and precision (relative standard deviation or RSD %) were evaluated at the fortification levels of 0.1, 0.5, and 2μg/g in seven replicates in both soybean and corn samples.

Direct Determination of Glyphosate, Glufosinate, and AMPA in milk by Liquid chromatography/tandem mass spectrometry

A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for the determination of glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate in milk using a reversed-phase liquid chromatography column with weak anion/cation exchange stationary phase. One milliliter of milk was shaken with three milliliters of water containing Na2EDTA and acetic acid for 10 minutes, to precipitate the protein content in the sample. After centrifugation, the supernatant was passed through an Oasis HLB SPE to retain suspended particulates and phospholipids. The sample was directly injected and analyzed in 6 min, with no sample concentration or derivatization steps. Two multiple reaction monitoring (MRM) channels were monitored in the method for each target compound to achieve true positive identification. Three internal standards corresponding to each analyte were used to counter matrix suppression effects. The linearity of the detector response was demonstrated in the range of 4 to 1000 ng/mL for each analyte, with a minimum coefficient of determination (R2) value of more than 0.995. Through the use of this internal standard calibration method, the average recovery for all analytes at 0.025, 0.1, 0.5, and 2 µg/g (n = 7) are between 84-111% with a relative standard deviation of less than 8%.https://doi.org/10.21423/jrs-v03n02p020 (DOI assigned 8/7/2019)

Direct aqueous determination of glyphosate and related compounds by liquid chromatography/tandem mass spectrometry using reversed-phase and weak anion-exchange mixed-mode column

Analysis of the broad-spectrum herbicide glyphosate and its related compounds is quite challenging. Tedious and time-consuming derivatization is often required for these substances due to their high polarity, high water solubility, low volatility and molecular structure which lacks either a chromophore or fluorophore. A novel liquid chromatography/tandem mass spectrometry (LC/MS–MS) method has been developed for the determination of glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate using a reversed-phase and weak anion-exchange mixed-mode Acclaim ® WAX-1 column. Aqueous environmental samples are directly injected and analyzed in 12 min with no sample concentration or derivatization steps. Two multiple reaction monitoring (MRM) channels are monitored in the method for each target compound to achieve true positive identification, and 13C, 15N-glyphosate is used as an internal standard to carry out isotope dilution mass spectrometric (IDMS) measurement for glyphosate. The instrument detection limits (IDLs) for glyphosate, AMPA and glufosinate are 1, 2 and 0.9 μg/L, respectively. Linearity of the detector response with a minimum coefficient of determination ( R 2) value ( R 2 > 0.995) was demonstrated in the range of ∼10 to 10 3 μg/L for each analytes. Spiked drinking water, surface water and groundwater samples were analyzed using this method and the average recoveries of analytes in three matrices ranged from 77.0 to 102%, 62.1 to 101%, 66.1 to 93.7% while relative standard deviation ranged from 6.3 to 10.2%, 2.7 to 14.8%, 2.9 to 10.7%, respectively. Factors that may affect method performance, such as metal ions, sample preservation, and storage time, are also discussed.

Extended octagonal ring transducers for measurement of tractor-implement forces

The extended octagonal ring transducers are popular devices for force and moment measurements in agricultural engineering research due to its capability in measuring forces independently in two dimensions and resultant moment in one dimension. In this study design, construction and calibration of extended octagonal ring transducers are discussed. The transducers were designed to measure the two force components of the soil reaction with minimum cross-sensitivity. Strain distributions in the extended octagonal rings were analyzed using finite element method to locate optimal strain gauge positions to minimize cross-sensitivity between the two force components. A Data acquisition system consisted of a programmable DT800 data logger with 12 differential voltage and 16 frequency channels, and a PC for storing the data for further graphing and analysis. The system was tested for its sensitivity, cross-sensitivity, linearity and repeatability. The results of the calibration tests revealed that the system was well working for a range of draught and vertical forces up to 25 kN. The results showed a high degree of linearity between bridge output voltage and force applied. The minimum coefficient of determination, R2, was found to be 0.99. The interactions of the applied forces on the orthogonal force bridges were less than one percent. The system could best be used for the measurement of draught (horizontal) and vertical forces where medium size equipment is attached with a tractor.

A daily runoff simulation in semi-arid watersheds based on soil water deficit calculations

Initial soil water content just before a rainfall event is an input required for the calculation of a basin's water balance including infiltration and runoff. However, for most watersheds such information is not available because its evaluation involves a large amount of labor. The objective of this study is to describe a practical model with which to estimate time-dependent changes of a basins soil water content. It is further used for predicting runoff water yield when rainfall depth is the only known component of the water balance equation (WBE). Two distinct cases of the WBE are discussed: (1) a runoff-producing storm; (2) a storm without runoff. Runoff events from four watersheds in southern Arizona were measured throughout 8 to 17 years and analyzed in this study. Rainfall-runoff relationships are described in this model by an empirical quadratic regression equation which includes four parameters. They were estimated by an optimization subroutine which was used to determine the minimum difference between measured and modeled results. The optimized parameters enable simulations of the continuous dynamic change of an index of the soil water content as well as predictions of runoff depths. It was found that the predicted runoff agrees reasonably well with the observed runoff. The minimum coefficient of determination ( r 2) between the computed and actual runoff for the multi-annual data sets was 0.62 and the maximum 0.86. Runoff threshold value was found to be a function of the basin average soil texture. The lowest threshold was 4.6 mm for clay soil and the largest was 9.0 mm for sandy soil. Since direct soil water measurements were not taken, we interpreted the acceptable agreement between measured and predicted runoff as an indirect validation of the soil water model. It is concluded that the model could be useful for extending short records of simulated runoff on nearby ungaged watersheds in semi-arid regions.