A biosafety level (BSL) laboratory is a set of biocontainment preventative measures used to prevent and isolate hazardous biological agents or their accidental release in a laboratory. It is vital to provide a negative-pressurized environment for disease infection control. The experimental equipment layout may affect the personnel’s exposure to infection. However, the equipment layout and exhaust air grilles were in a fixed position in this investigated BSL. Due to retrofitting, the layout arrangement of HEPA as supply air is investigated numerically. Computational Fluid Dynamics (CFD) simulation is conducted to analyze and determine a better design for contamination control. This study proposes three ventilation arrangements as an alternative design, including vertical arrangement, horizontal arrangement, and L-shaped ventilation arrangements (instead of the supply being arranged in a single line). In addition, the airflow distribution, concentration decay, air of age, ventilation, and removal effectiveness are all examined in the study. The numerical simulation results were verified by a field measurement test. The results revealed that the L-shaped ventilation arrangement for supply air diffusers would achieve better ventilation and removal efficiency. The local mean age of air was also identified as the most satisfactory ventilation performance measure, as it shows the level of contaminant control. It also indicated that ventilation could be improved by arranging the supply air layout with less expenditure through CFD-aided simulation in identifying strategies for best practices for the design stage to reduce the running cost at full operation.

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Strategies to Enhance Contamination Control Performance through Ventilation Improvement in a Biosafety Laboratory Building

Screening those individuals who are latent but at higher risk of rapidly developing active tuberculosis (TB) is one of the intervention measures to control the spread of TB. This work proposes a TB SVELIT (S‐Susceptible, V‐Vaccinated, E‐Early latent, L‐Late latent, I‐Infected, T‐Treated) transmission model with relapse. In particular, a complete threshold dynamical analysis for the model is performed and the existence of optimal control is obtained. Meanwhile, the validity of the model is shown by comparing the real data with the fitted curve and the future trend in the incidence of TB in China is predicted. More importantly, the effects of four strategies, including vaccination, media propaganda, screening latent individuals, and receiving treatment, are evaluated numerically. The results suggest that the above four strategies can effectively control TB and shorten the duration of the epidemic. Interestingly, treatment is more effective than vaccination in controlling TB, but media propaganda and latent screening are cheaper and easier to implement.

A tuberculosis model with early and late latency, imperfect vaccination, and relapse: An application to China

The problem of nonlinear adaptive control for a class of fractional-order tuberculosis (TB) model is studied in this paper. By analyzing the transmission mechanism of TB and the characteristics of fractional calculus, a fractional-order TB dynamical model is established with media coverage and treatment as control variables. With the help of universal approximation principle of radial basis function neural networks and the positive invariant set of established TB model, the expressions of control variables are designed and the stability of error model is analyzed. Thus, the adaptive control method can guarantee that the number of susceptible and infected individuals can be kept close to the corresponding control targets. Finally, the designed control variables are illustrated by numerical examples. The results indicate that the proposed adaptive controllers can effectively control the established TB model and ensure the stability of controlled model, and two control measures can protect more people from tuberculosis infection.

Nonlinear neural networks adaptive control for a class of fractional-order tuberculosis model.

A tuberculosis epidemic model as a proxy for the assessment of the novel <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e1471" altimg="si3.svg"><mml:mrow><mml:mi>M</mml:mi><mml:mn>72</mml:mn><mml:mo>/</mml:mo><mml:mi>A</mml:mi><mml:mi>S</mml:mi><mml:mn>0</mml:mn><mml

Global analysis of tuberculosis dynamical model and optimal control strategies based on case data in the United States

This paper formulates a diffusive tuberculosis (TB) model with early and late latent infections, vaccination and treatment that may more properly describe the slow and fast dynamics of TB transmission. We develop a new concise approach to determine the combination coefficients in the Lyapunov function candidate for the model and its time derivative in the case that both are the linear combinations of several Volterra-type functions, which highly simplifies the computations in global dynamical analysis for the nonlinear high-dimensional model. Based on the TB case data reported in China, the parameter values of the model are estimated. We further predict the TB prevalence trend in China. Sensitivity analysis for the control reproduction number and endemic equilibrium is conducted to seek some effective interventions that can significantly reduce initial TB transmission and lower TB prevalence levels in China. In the end, numerical simulations show that the bigger diffusive rates pick up the speeds of convergence to the equilibria of the model.

A diffusive tuberculosis model with early and late latent infections: New Lyapunov function approach to global stability

Coal mine underground environment gases gas composition is very complicated, especially coal self-ignition different oxidation stage symbol of mine gas and release of period of reckoning produce of the coal mine enterprises poisonous and harmful gas production safety, caused great harm to the mine production period and needed after the reckoning mine air composition for monitoring. Existing gas chromatographic analysis is slow and not on-line analysis problem, sensor use short-lived, need often set-up insufficient, we put forward such a kind of brand-new based on the Fourier transform infrared spectrometer (FTIR) in-well environment gas analysis method. Combining with gas absorption spectral characteristics and analysis from spectrometer parameter selection, request the sample gas preparation, feature extraction and analysis model is established in variable introduces a set of effective coal mine underground environment gas spectral analysis method, and then gives C2H6, C3H8, CH4, i-C4H10, n-C4H10, C2H4 C3H6, C2H2, SF6, CO and CO2, the test results. The results showed that the FTIR spectrometer in spectral resolution for 1cm-1, optical path for 10cm circumstances, all gas resolution than 2x10-6, meet mine environment gas detection requirements. This shows that the infrared spectrum analysis is a potential mine environment gas analysis, this paper party could realize technology of coal mine underground environment gas on-line analysis.

Lian Cong Wang

Papers

Global analysis of tuberculosis dynamical model and optimal control strategies based on case data in the United States

A diffusive tuberculosis model with early and late latent infections: New Lyapunov function approach to global stability

Quantitative Analysis and Study of Coal Mine Underground Environment Gases Based on the FTIR