scholarly journals Gompertz model in COVID-19 spreading simulation

2021 ◽  
pp. 111699
Author(s):  
E. Pelinovsky ◽  
M. Kokoulina ◽  
A. Epifanova ◽  
A. Kurkin ◽  
O. Kurkina ◽  
...  
Keyword(s):  
Gompertz Model

scholarly journals Batch Anaerobic Co-Digestion and Biochemical Methane Potential Analysis of Goat Manure and Food Waste

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1952
Author(s):  
Ayobami Orangun ◽  
Harjinder Kaur ◽  
Raghava R. Kommalapati
Keyword(s):  
Food Waste ◽  
Gompertz Model ◽  
Water Displacement ◽  
Biochemical Methane Potential ◽  
Greenhouse Gasses ◽  
Nonlinear Regression Models ◽  
The Us ◽  
Methane Potential ◽  
Goat Manure ◽  
Modified Gompertz Model

The improper management of goat manure from concentrated goat feeding operations and food waste leads to the emission of greenhouse gasses and water pollution in the US. The wastes were collected from the International Goat Research Center and a dining facility at Prairie View A&M University. The biochemical methane potential of these two substrates in mono and co-digestion at varied proportions was determined in triplicates and processes were evaluated using two nonlinear regression models. The experiments were conducted at 36 ± 1 °C with an inoculum to substrate ratio of 2.0. The biomethane was measured by water displacement method (pH 10:30), absorbing carbon dioxide. The cumulative yields in goat manure and food waste mono-digestions were 169.7 and 206.0 mL/gVS, respectively. Among co-digestion, 60% goat manure achieved the highest biomethane yields of 380.5 mL/gVS. The biodegradabilities of 33.5 and 65.7% were observed in goat manure and food waste mono-digestions, while 97.4% were observed in the co-digestion having 60% goat manure. The modified Gompertz model is an excellent fit in simulating the anaerobic digestion of food waste and goat manure substrates. These findings provide useful insights into the co-digestion of these substrates.

scholarly journals A generalized Gompertz growth model with applications and related birth-death processes

2020 ◽  
Author(s):  
Majid Asadi ◽  
Antonio Di Crescenzo ◽  
Farkhondeh A. Sajadi ◽  
Serena Spina
Keyword(s):  
Growth Model ◽  
Growth Curve ◽  
Goodness Of Fit ◽  
Gompertz Model ◽  
Death Process ◽  
Birth Process ◽  
Failure Data ◽  
First Case ◽  
Gompertz Growth Model ◽  
Birth Death

AbstractIn this paper, we propose a flexible growth model that constitutes a suitable generalization of the well-known Gompertz model. We perform an analysis of various features of interest, including a sensitivity analysis of the initial value and the three parameters of the model. We show that the considered model provides a good fit to some real datasets concerning the growth of the number of individuals infected during the COVID-19 outbreak, and software failure data. The goodness of fit is established on the ground of the ISRP metric and the $$d_2$$ d 2 -distance. We also analyze two time-inhomogeneous stochastic processes, namely a birth-death process and a birth process, whose means are equal to the proposed growth curve. In the first case we obtain the probability of ultimate extinction, being 0 an absorbing endpoint. We also deal with a threshold crossing problem both for the proposed growth curve and the corresponding birth process. A simulation procedure for the latter process is also exploited.

scholarly journals Biomethane Potential of Sludges from a Brackish Water Fish Hatchery

2021 ◽  
Vol 11 (2) ◽  
pp. 552
Author(s):  
Francesco da Borso ◽  
Alessandro Chiumenti ◽  
Giulio Fait ◽  
Matia Mainardis ◽  
Daniele Goi
Keyword(s):  
Brackish Water ◽  
Gompertz Model ◽  
Experimental Tests ◽  
Lag Phase ◽  
Phase Duration ◽  
Fish Hatchery ◽  
Volatile Solids ◽  
Water Recirculation ◽  
Methane Potential ◽  
Intensive Aquaculture

The development of intensive aquaculture is facing the challenge of the sustainable management of effluents. The reproductive sectors (i.e., hatcheries) mainly use water recirculation systems (RAS), which discharge a portion of wastewater. Anaerobic digestion (AD) could reduce the environmental impact of this waste stream while producing biogas. The study is focused on the biochemical methane potential (BMP) of brackish fish hatchery sludges. Wastewater was concentrated by microfiltration and sedimentation and thickened sludges were treated in a BMP system with different inoculum/substrate (I/S) volatile solids ratios (from 50:1 to no inoculum). The highest I/S ratio showed the highest BMP (564.2 NmL CH4/g VS), while different I/S ratios showed a decreasing trend (319.4 and 127.7 NmL CH4/g VS, for I/S = 30 and I/S = 3). In absence of inoculum BMP resulted of 62.2 NmL CH4/g VS. The kinetic analysis (modified Gompertz model) showed a good correlation with the experimental data, but with a long lag-phase duration (from 14.0 to 5.5 days) in particular with the highest I/S. AD applied to brackish water sludges can be a promising treatment with interesting methane productions. For a continuous, full-scale application further investigation on biomass adaptation to salinity and on retention times is needed. Further experimental tests are ongoing.

scholarly journals Optimizing anaerobic co-digestion of goat manure and cotton gin trash using biochemical methane potential (BMP) test and mathematical modeling

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
Harjinder Kaur ◽  
Raghava R. Kommalapati
Keyword(s):  
Liquid Fraction ◽  
Gompertz Model ◽  
Biochemical Methane Potential ◽  
Methane Potential ◽  
Mathematical Equations ◽  
Goat Manure ◽  
Bmp Test ◽  
Batch Bioreactors ◽  
Modified Gompertz Model ◽  
Cotton Gin

AbstractAnaerobic co-digestion is widely adopted to enhance process efficacy by balancing the C/N ratio of the feedstock while converting organic wastes to biomethane. Goat manure (GM) and cotton gin trash (CGT) were anaerobically co-digested in triplicate batch bioreactors. The process was optimized and evaluated utilizing mathematical equations. The liquid fraction of the digestate was analyzed for nitrate and phosphate. The co-digestions with 10 and 20% CGT having the C/N ratios of 17.7 and 19.8 yielded the highest and statistically similar 261.4 ± 4.8 and 262.6 ± 4.2 mL/gvs biomethane, respectively. The biodegradability (BD) of GM and CGT was 94.5 ± 2.7 and 37.6 ± 0.8%, respectively. The BD decreased proportionally with an increase in CGT percentage. The co-digestion having 10% CGT yielded 80–90% of biomethane in 26–39 d. The modified Gompertz model-predicted and experimental biomethane values were similar. The highest synergistic effect index of 15.6 ± 4.7% was observed in GM/CGT; 30:70 co-digestion. The concentration of nitrate and phosphate was lower in the liquid fraction of digestate than the feedstocks, indicating that these nutrients stay in the solid fraction. The results provide important insights in agro-waste management, further studies determining the effects of effluent application on plants need to be conducted.

scholarly journals A Study on the Feasibility of Anaerobic Co-Digestion of Raw Cheese Whey with Coffee Pulp Residues

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3611
Author(s):  
Sandra Gonzalez-Piedra ◽  
Héctor Hernández-García ◽  
Juan M. Perez-Morales ◽  
Laura Acosta-Domínguez ◽  
Juan-Rodrigo Bastidas-Oyanedel ◽  
...  
Keyword(s):  
Methane Production ◽  
Kinetic Models ◽  
Cheese Whey ◽  
Maximum Yield ◽  
Gompertz Model ◽  
Coffee Pulp ◽  
The One ◽  
The Cost ◽  
Best Fit ◽  
Cheese Production

In this paper, a study on the feasibility of the treatment of raw cheese whey by anaerobic co-digestion using coffee pulp residues as a co-substrate is presented. It considers raw whey generated in artisanal cheese markers, which is generally not treated, thus causing environmental pollution problems. An experimental design was carried out evaluating the effect of pH and the substrate ratio on methane production at 35 °C (i.e., mesophilic conditions). The interaction of the parameters on the co-substrate degradation and the methane production was analyzed using a response surface analysis. Furthermore, two kinetic models were proposed (first order and modified Gompertz models) to determine the dynamic profiles of methane yield. The results show that co-digestion of the raw whey is favored at pH = 6, reaching a maximum yield of 71.54 mLCH4 gVSrem−1 (31.5% VS removed) for raw cheese whey and coffee pulp ratio of 1 gVSwhey gVSCoffe−1. The proposed kinetic models successfully fit the experimental methane production data, the Gompertz model being the one that showed the best fit. Then, the results show that anaerobic co-digestion can be used to reduce the environmental impact of raw whey. Likewise, the methane obtained can be integrated into the cheese production process, which could contribute to reducing the cost per energy consumption.

scholarly journals A Multi-Model Approach to Implement a Dynamic Shelf Life Criterion in Meat Supply Chains

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2740
Author(s):  
Antonia Albrecht ◽  
Maureen Mittler ◽  
Martin Hebel ◽  
Claudia Waldhans ◽  
Ulrike Herbert ◽  
...  
Keyword(s):  
Shelf Life ◽  
Real Time ◽  
Ph Value ◽  
Gompertz Model ◽  
Quality Parameters ◽  
Viable Count ◽  
Short Sales ◽  
Time Dynamic ◽  
Sensory Data ◽  
Model Approach

The high perishability of fresh meat results in short sales and consumption periods, which can lead to high amounts of food waste, especially when a fixed best-before date is stated. Thus, the aim of this study was the development of a real-time dynamic shelf-life criterion (DSLC) for fresh pork filets based on a multi-model approach combining predictive microbiology and sensory modeling. Therefore, 647 samples of ma-packed pork loin were investigated in isothermal and non-isothermal storage trials. For the identification of the most suitable spoilage predictors, typical meat quality parameters (pH-value, color, texture, and sensory characteristics) as well as microbial contamination (total viable count, Pseudomonas spp., lactic acid bacteria, Brochothrix thermosphacta, Enterobacteriaceae) were analyzed at specific investigation points. Dynamic modeling was conducted using a combination of the modified Gompertz model (microbial data) or a linear approach (sensory data) and the Arrhenius model. Based on these models, a four-point scale grading system for the DSLC was developed to predict the product status and shelf-life as a function of temperature data in the supply chain. The applicability of the DSLC was validated in a pilot study under real chain conditions and showed an accurate real-time prediction of the product status.

scholarly journals ISO 22000 Certification: Diffusion in Europe

Resources ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 100
Author(s):  
Nathalia Granja ◽  
Pedro Domingues ◽  
Mónica Cabecinhas ◽  
Dominik Zimon ◽  
Paulo Sampaio
Keyword(s):  
Safety Management ◽  
Research Question ◽  
Gompertz Model ◽  
Iso 14001 ◽  
Iso 9001 ◽  
Management Systems ◽  
Safety Management Systems ◽  
Cross Sectional ◽  
European Continent ◽  
Forecasting Models

The main aim of this paper is to answer the research question, “Is the Gompertz model suitable for studying the diffusion of the ISO 22000 standard in Europe?” Forecasting models adopting the Gompertz model were developed to estimate to which extent the Food Safety Management Systems (FSMS) based on the ISO 22000 standard are expected to be implemented and certified in the European continent. To provide a forecast for the next few years, data from the diffusion of renowned ISO standards, namely, ISO 9001 and ISO 14001, were extrapolated in order to overcome the shortcoming since data concerning ISO 22000 certification was only available for the period 2007 to 2018. The results provide a cross-sectional portrayal of the European diffusion of ISO 22000 certification and suggest an interval of the estimated number of certificates issued in Europe. This research paper presents the first attempt to empirically analyze the dynamic of diffusion of the European ISO 22000 certification. A more accurate fitting with real results may be expected with further information available in the forthcoming years.

scholarly journals Analysis of German BSE Surveillance Data: Estimation of the Prevalence of Confirmed Cases versus the Number of Infected, but Non-Detected, Cattle to Assess Confidence in Freedom from Infection

2021 ◽  
Vol 18 (19) ◽  
pp. 9966
Author(s):  
Matthias Greiner ◽  
Thomas Selhorst ◽  
Anne Balkema-Buschmann ◽  
Wesley O. Johnson ◽  
Christine Müller-Graf ◽  
...  
Keyword(s):  
Food Chain ◽  
Gompertz Model ◽  
Credible Interval ◽  
Surveillance Data ◽  
Point Estimate ◽  
Surveillance Program ◽  
Birth Cohorts ◽  
Detection Probabilities ◽  
Freedom From Disease ◽  
Data Estimation

Quantitative risk assessments for Bovine pongiform ncephalopathy (BSE) necessitate estimates for key parameters such as the prevalence of infection, the probability of absence of infection in defined birth cohorts, and the numbers of BSE-infected, but non-detected cattle entering the food chain. We estimated three key parameters with adjustment for misclassification using the German BSE surveillance data using a Gompertz model for latent (i.e. unobserved) age-dependent detection probabilities and a Poisson response model for the number of BSE cases for birth cohorts 1999 to 2015. The models were combined in a Bayesian framework. We estimated the median true BSE prevalence between 3.74 and 0.216 cases per 100,000 animals for the birth cohorts 1990 to 2001 and observed a peak for the 1996 birth cohort with a point estimate of 16.41 cases per 100,000 cattle. For birth cohorts ranging from 2002 to 2013, the estimated median prevalence was below one case per 100,000 heads. The calculated confidence in freedom from disease (design prevalence 1 in 100,000) was above 99.5% for the birth cohorts 2002 to 2006. In conclusion, BSE surveillance in the healthy slaughtered cattle chain was extremely sensitive at the time, when BSE repeatedly occurred in Germany (2000–2009), because the entry of BSE-infected cattle into the food chain could virtually be prevented by the extensive surveillance program during these years and until 2015 (estimated non-detected cases/100.000 [95% credible interval] in 2000, 2009, and 2015 are 0.64 [0.5,0.8], 0.05 [0.01,0.14], and 0.19 [0.05,0.61], respectively).

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