Non Binary Low Density Parity Check Codes Decoding Over Galois Field

Conventional LDPC codes have a low decoding complexity but may have high encoding complexity. The encoding complexity is typically of the order O(n2)[5]. Also high storage space may be required to explicitly store the generator matrix. For long blocknbsp lengths the storage space required would be huge. The above factors make the implementation of the Conventional LDPC codes less attractive. These codes are usually decoded using the sum-product algorithm, which is anbsp message passing algorithm working on the Tanner graph of the code[5]. The sparseness of the parity check matrix is essential for attaining good performance with sum-product decoding. The time complexity of the sum- product algorithm is linear in code length. This property makes it possible to implement a practical decoder for long lengths.nbs

Evaluation of Lung Volume and Effect of Vital Staining as Motivation to Quit Tobacco among Nicotine Dependents of Kanpur, India

Objective: To quantify and compare respiratory functions and further screen the oral mucosa of tobacco and non-tobacco users. Material and Methods: First control group, non-tobacco users (n=55); Second group, smokers’ group (n=168) who currently smoked cigarettes; Third group smokeless/chewing type, tobacco group (n=81); Fourth group, both smokeless and smoking type tobacco users (n=46). Fagerstrom Test for Nicotine Dependences (FTND) and Fagerström Test for Nicotine Dependence-Smokeless Tobacco (FTND-ST) instruments were used to assess nicotine dependence. Subsequently, spirometry and Toluidine Blue (TB) vital staining were performed. Chi-squared and one-way analysis of variance (ANOVA) were used for statistical analysis. Results: Fagerstrom test resulted in 48.8% of subjects with low dependency, followed by an increase in nicotine dependency from low to moderate (29.2%), moderate (15.6%), and highly dependent (6.4%) groups. All respiratory function tests and oral screening confirmed significant changes amongst tobacco and non-tobacco users. The forced vital capacity of non-smoker group was significantly different from other tobacco users’ group (p<0.05). Conclusion: Early effects of tobacco use can lead to complications with the respiratory system and oral cavity. Such data can be used to delineate the harm of tobacco and should be used to urge individuals to evade the utilization of tobacco

Calibration and Evaluation of Subsurface Drainage Component of RZWQM V.2.5

This study was designed to calibrate and evaluate the subsurface drain flow component of the Root Zone Water Quality Model (RZWQM; Version 2.5) for four tillage-systems: chisel plow (CP), moldboard plow (MB), no-tillage (NT), and ridge-tillage (RT). Measured subsurface drain flow data for 1990 was used for model calibration. Main parameters calibrated were lateral saturated hydraulic conductivity, and effective porosity. Subsurface drain flow predictions were made using calibrated parameters and compared with measured subsurface drain flows for 1991 and 1992. Measured subsurface drain flow data for all 3 yrs was obtained from the Nashua Water Quality Site in Iowa. The model, in general, showed a good agreement between measured and predicted subsurface drain flow values, although discrepancies existed for several days of a given year. Coefficients of determination calculated for predicted vs. measured daily subsurface drain flows ranged from 0.51 to 0.68 for 1990, 0.70 to 0.78 for 1991, and 0.54 to 0.69 for 1992. Simulated tillage effect on subsurface drain flows for 1991 and 1992 were consistent with those for calibrated year 1990 (maximum subsurface drain flow was observed under NT and minimum under MB). However, observed tillage effects varied from year to year, indicating a change in soil hydraulic properties, e.g., macroporosity. Other factors that could have caused the discrepancies between measured and simulated subsurface drain flows were: groundwater flux due to natural gradient, deep seepage, inaccuracies involved in the estimation of breakpoint rainfall data, and spatial variability in soil properties

Simulating nitrogen management effects of subsurface drainage water quality

Increased level of NO3-N in the drinking water supplies is a major health concern these days. The long-term effects of actual nitrogen (N) fertilizer management practices are not well understood. The use of computer models allows the simulation of different N management practices on a long-term basis and their related effects on water quality. The RZWQM (Root Zone Water Quality Model, Version 3.0) was used to simulate the long-term (1978–1992) impacts of N management practices (single N applications at 50, 100, 150, and 200 kg per ha; and single and split N applications at 150 and 200 kg per ha) on NO3-N losses with subsurface drain flows and crop yields under two tillage systems (moldboard plow (MB) and no till (NT)). Simulations conducted in this study were based on input parameters calibrated by Singh et al. (J. Environ. Qual., in press) for NO3-N transport to subsurface drains. However, calibration of some additional parameters was required in this study for long-term simulations. The long-term climatic data and soil properties data for these simulations were obtained from a water quality research site at Nashua, Iowa. The results of this study showed that increasing rates of N applications (50, 100, 150, and 200 kg per ha) resulted in increased NO3-N losses with subsurface drain flows and increased crop yields. However, increasing rates of NO3-N losses and crop yields were not linearly proportional with increasing rates of N applications. These trends were similar for both MB and NT treatments. Also, NO3-N losses and crop yields were not significantly different under single and split N applications at both 150 and 200 kg per ha levels of application. The single N application of 150 kg per ha was considered the best N application practice as the simulated NO3-N losses under this practice were reduced considerably (40.3% less in MB and 52.4% less in NT) when compared with the single N application of 200 kg per ha. At the same time, the reduction in crop yields at 150 kg per ha single N application was very small (5.9% reduction under MB and about 6.1% under NT) when compared with the crop yields at 200 kg per ha single N application. This study also shows that RZWQM can be used successfully in evaluating similar N management schemes for other geographic regions of the world by utilizing site-specific data on soils, geological features, crops, and climatic parameters such as rainfall and evaporation

Simulating Atrazine Transport Using Root Zone Water Quality Model for Iowa Soil Profiles

The pesticide component of the Root Zone Water Quality Model (RZWQM) was calibrated and evaluated for two tillage systems: no-till (NT) and moldboard plow (MB). The RZWQM is a process-based model that simulates the water and chemical transport processes in the soil-crop-atmosphere system. Observed data on atrazine concentrations in the soil profile, for model calibration and testing, were obtained from a field study in Iowa. Two statistical parameters, maximum error (ME) and coefficient of determination (CD), were used to evaluate the ability of the RZWQM to predict atrazine concentrations in the soil profile. The ME, CD, and other statistical tests indicated that there was a significant difference between predicted and observed atrazine concentrations. Comparison of simulated vs. observed atrazine concentrations with 1:1 line showed that atrazine concentrations were overpredicted, especially in the later part of the growing season. However, the model correctly predicted depth of atrazine penetration in the soil profile. Also, the range of predicted atrazine concentrations was within the same order of magnitude as observed concentrations. Although observed atrazine concentrations were usually higher in surface layers under MB than in NT treatment, the model did not show any consistent tillage effects on atrazine distribution in the soil profile. The results from this simulation study indicated that the following factors may be critical and should be considered when simulating pesticide transport in the subsurface environment: (i) macropore flow, (ii) variation in Koc and pesticide half-life with depth, and (iii) interception of pesticide by surface residue during application

Using RZWQM to Predict Herbicide Leaching Losses in Subsurface Drainage Water

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options. USING RZWQM TO PREDICT HERBICIDE LEACHING LOSSES IN SUBSURFACE DRAINAGE WATER Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org Citation: Transactions of the ASAE. Vol. 47(5): 1415-1426 . (doi: 10.13031/2013.17621) @2004 Authors: A. Bakhsh, L. Ma, L. R. Ahuja, J. L. Hatfield, R. S. Kanwar Keywords: Herbicides, RZWQM, Subsurface drainage, Water quality Improvements have been made in the pesticide component of the Root Zone Water Quality Model (RZWQM) since its release in 1999 for the Management System Evaluation Areas (MSEA) project. This study was designed to evaluate the herbicide leaching component of the model using data on subsurface drainage flow and herbicide leaching losses for a 6-year (1992 to 1997) period. A sensitivity analysis was conducted for the key parameters important in the pesticide calibration process. The model was calibrated using 1992 data and validated using 1993 to 1997 data collected from a tile-drained field within the Walnut Creek watershed in central Iowa. The model evaluation criterion was based on percent difference between the predicted and measured data (%D), root mean square error (RMSE), and model efficiency (EF). Atrazine and metolachlor were applied to corn in 1993, 1995, and 1997, and metribuzin was used during the soybean growing seasons in 1992, 1994, and 1996 at the standard application rates used in Iowa. The predicted subsurface drainage volumes were in close agreement with the measured data showing %D = 1, RMSE = 8, and EF = 0.99, when averaged over the validation years. Herbicide half-life (t1/2) and soil organic based partitioning coefficient (Koc) were found to be the most sensitive parameters for simulating herbicide leaching losses in subsurface drainage water. Both t1/2 and Koc affected the mass and temporal distribution of the herbicide leaching losses in subsurface drainage flows. The predicted herbicide leaching losses in subsurface drainage water were the same order of magnitude as the measured data, when averaged across the validation years. The study also revealed that herbicide leaching losses were significantly (P \u3c 0.05) controlled by the drainage volume (R2 = 0.97). The model, however, underpredicted herbicide leaching losses after crop harvest and during early spring, possibly because of preferential flow paths developed during these periods. More improvements may be needed in the RZWQM to consider the dynamics of the preferential flow paths development in cultivated soils similar to that of the study area

Evaluation of Lung Volume and Effect of Vital Staining as Motivation to Quit Tobacco among Nicotine Dependents of Kanpur, India

Objective: To quantify and compare respiratory functions and further screen the oral mucosa of tobacco and non-tobacco users. Material and Methods: First control group, non-tobacco users (n=55); Second group, smokers’ group (n=168) who currently smoked cigarettes; Third group smokeless/chewing type, tobacco group (n=81); Fourth group, both smokeless and smoking type tobacco users (n=46). Fagerstrom Test for Nicotine Dependences (FTND) and Fagerström Test for Nicotine Dependence-Smokeless Tobacco (FTND-ST) instruments were used to assess nicotine dependence. Subsequently, spirometry and Toluidine Blue (TB) vital staining were performed. Chi-squared and one-way analysis of variance (ANOVA) were used for statistical analysis. Results: Fagerstrom test resulted in 48.8% of subjects with low dependency, followed by an increase in nicotine dependency from low to moderate (29.2%), moderate (15.6%), and highly dependent (6.4%) groups. All respiratory function tests and oral screening confirmed significant changes amongst tobacco and non-tobacco users. The forced vital capacity of non-smoker group was significantly different from other tobacco users’ group (p<0.05). Conclusion: Early effects of tobacco use can lead to complications with the respiratory system and oral cavity. Such data can be used to delineate the harm of tobacco and should be used to urge individuals to evade the utilization of tobacco

RZWQM simulated effects of crop rotation, tillage, and controlled drainage on crop yield and nitrate-N loss in drain flow

Accurate simulation of agricultural management effects on N loss in tile drainage is vitally important for understanding hypoxia in the Gulf of Mexico. An experimental study was initiated in 1978 at Nashua, Iowa of the USA to study long-term effects of tillage, crop rotation, and N management practices on subsurface drainage flow and associated N losses. The Root Zone Water Quality Model (RZWQM) was applied to evaluate various management effects in several previous studies. In this study, the simulation results were further analyzed for management effects (tillage, crop rotation, and controlled drainage) on crop production and N loss in drain flow. RZWQM simulated the observed increase in N concentration in drain flow with increasing tillage intensity from NT (no-till) to RT (ridge till) to CP (chisel plow) and to MP (moldboard plow). It also adequately simulated tillage effects on yearly drain flow and yearly N loss in drain flow. However, the model failed to simulate lower corn and soybean yields under NT than under MP, CP, and RT. On the other hand, RZWQM adequately simulated lower yearly drain flow and lower flow-weighted N concentration in drain flow under CS (corn–soybean) and SC (soybean–corn) than under CC (continuous corn). The model adequately simulated higher corn yield under CS and SC than under CC. Applying the newly suggested N management practice for the Midwest of controlled drainage, the model simulated a 30% reduction in drain flow and a 29% decrease in N losses in drain flow under controlled drainage (CD) compared to free drainage (FD). With most of the simulations in reasonably close agreement with observations, we concluded that RZWQM is a promising tool for quantifying the relative effects of tillage, crop rotation, and controlled drainage on N loss in drainage flow. Further improvements on simulated management effects on crop yield and N mineralization are needed, however

Sensitivity of tile drainage flow and crop yield on measured and calibrated soil hydraulic properties

Process-based agricultural system models require detailed description of soil hydraulic properties that are usually not available. The objectives of this study were to evaluate the sensitivity of model simulation results to variability in measured soil hydraulic properties and to compare simulation results using measured and default soil parameters. To do so, we measured soil water retention curves and saturated soil hydraulic conductivity (Ksat) from intact soil cores taken from a long-term experimental field near Nashua, Iowa for the Kenyon–Clyde–Floyd–Readlyn soil association. The soil water retention curves could be well described using the pore size distribution index (λ). Measured λ values from undisturbed soil cores ranged from 0.04 to 0.12 and the measured Ksat values ranged from 1.8 to 14.5 cm/h. These hydraulic properties were then used to calibrate the Root Zone Water Quality Model (RZWQM) for simulating soil water content, water table, tile drain flow, and crop yield (corn and soybean) by optimizing the lateral Ksat(LKsat) and hydraulic gradient (HG) for subsurface lateral flow. The measured soil parameters provided better simulations of soil water storage, water table, and N loss in tile flow than using the default soil parameters based on soil texture classes in RZWQM. Sensitivity analyses were conducted for λ, Ksat, saturated soil water content (θs) or drainable porosity, LKsat, and HG using the Latin Hypercubic Sampling (LHS) and for LKsat and HG also using a single variable analysis. Results of sensitivity analyses showed that RZWQM-simulated yield and biomass were not sensitive to soil hydraulic properties. Simulated tile flow and N losses in tile flow were not sensitive to λ and Ksat either, but they were sensitive to LKsat and HG. Further sensitivity analyses using a single variable showed that LKsat in the tile layer was a more sensitive parameter compared to LKsat in other soil layers, and HG was the most sensitive parameter for tile flow under the experimental soil and weather conditions