Software sensors for biomass concentration estimation in filamentous microorganism cultivation process

In this study, the potential of two software sensors for on-line estimation of biomass concentration during cultivation of filamentous microorganisms is examined. The first sensor is based on common bioreactor off-gas analyses, and uses the assumption of the biomass concentration linear dependence on the square root of cumulative O-2, consumption. Parameters of the semi-empirical data-driven software sensor based on off-gas analysis were calculated from experimental cultivation data using linear regression. The second sensor is based on biocalorimetry, i.e., the on-line calculation of metabolic heat flux from general enthalpy balance of the bioreactor. The software sensor based on biocalorimetry thus essentially represents a model-driven approach, making use of a fundamental process model based on the enthalpy balance around the bioreactor. This approach has been combined with the experimental identification of the specific biomass heat production, which represents the main process-specific parameter of the software sensor based on biocalorimetry. For this sensor, the accuracy requirements on the process variable on-line measurements were also analysed. The experimental data from the pilot-scale antibiotics Nystatin production by a bacterium Streptomyces noursei were used to calculate the specific bioprocess heat production value using linear regression. The achieved results enabled us to propose a new on-line indicator calculated as the ratio of the outputs of both sensors, which can serve as a timely warning of the risk of undesired nutritional conditions of a culture characterized as underfeeding.Technology Agency of the Czech Republic [TA03010165

Crack Propagation Analysis of Compression Loaded Rolling Elements

The problem of crack propagation from internal defects in thermoplastic cylindrical bearing elements is addressed in this paper. The crack propagation in these elements takes place under mixed-mode conditions-i.e., all three possible loading modes (tensile opening mode I and shear opening modes II and III) of the crack are combined together. Moreover, their mutual relation changes during the rotation of the element. The dependency of the stress intensity factors on the crack length was described by general parametric equations. The model was then modified by adding a void to simulate the presence of a manufacturing defect. It was found that the influence of the void on the stress intensity factor values is quite high, but it fades with crack propagating further from the void. The effect of the friction between the crack faces was find negligible on stress intensity factor values. The results presented in this paper can be directly used for the calculation of bearing elements lifetime without complicated finite element simulations

Side-groove effect on fracture mechanical fatigue testing of PLA material

PLA polymer is probably the most used thermoplastic material in FDM technology nowadays. Besides prototyping purposes, FDM materials are also considered for functional application use, thanks to the fast fabrication of components, relatively simple workflow, and the absence of material waste that this technology offers. Except for static material properties, data concerning the expected lifetime and reliability of AM parts under cyclic loading are also necessary for functional purposes. Due to the exceptional structural complexity of FDM parts, minor modifications in material testing must be used sometimes. The subject of this paper is the fracture mechanics-based fatigue testing of CT specimens that results in crack kinetics description like the Paris' law. One of the objectives is also to describe the effect of SGs placed on the surface of CT specimens, and the effect of different layer heights. The main intention of the SGs is to secure a straight crack propagation path, thus imposing the crack to follow the Mode I condition, predominantly. A set of regular CT specimens and specimens with SGs was prepared with a full infill density interior and with different layer heights (0.1 mm and 0.3 mm). Crack kinetics measured on these specimens are presented in this paper and discussed

Prevention of children risk bahaviours in interactions with dogs

Dog attacks on children are a widespread problem, which can occur when parents fail to realise a potentially dangerous interaction between a dog and a child. The aim of the study was to evaluate dogs attacks to children in Czech households, the ability of parents to identify dangerous situations from several everyday child - dog interactions, determine whether the participants connected these situations to a particular breed of dog and whether participants intend to participate in the dog bite preventing program for them and their children. Data were presented via an online survey to parents of children no more than 6 years old. Data from 208 respondents were analysed using procedure GLIMMIX in SAS program, version 9.3 and Pearson's Chi-squared test in program "R". We recorded 19 dogs attacks on children and children always knew attacking dog. Parents were present and supervised 18 children when attacks happened. Three children had to receive medical help after being attacked by a dog and one developed a post-traumatic stress disorder - a phobia of dogs. Most participants would welcome educating programs about child - dog interactions, more often those who owned a dog (p < 0,05). The probability of risk assessment varied according to dog breed (p < 0.001) as well as to the depicted situation (p < 0,001). Results indicated that Labrador Retriever was considered the least likely of the three dogs to be involved in a dangerous dog - child interaction (with 49 % predicting a dangerous interaction), followed by Parson Russell Terrier (63.2 %) and American Pit Bull Terrier (65 %). Participants considered one particular dog-child interaction named 'touching a bowl' a dangerous interaction at a high rate (77.9 %) when compared with the other presented situations, which were assessed as dangerous at rates of 48.4 % to 56.5 %. The breed of dog seems to be an influential factor when assessing a potentially dangerous outcome from a dog - child interaction. Contrary to our hypothesis, interactions involving the small dog (Parson Russell Terrier) were rated more critically, similarly to those of the American Pit Bull Terrier. These results suggest that even popular family dog breeds, such as Labrador Retrievers, should be treated with more caution

Digital image analysis for morphological state characterization of a culture of filamentous microorganisms in production of antibiotics

The paper deals with the application of specific methods of digital image analysis for the monitoring of morphological changes in cultures of filamentous microorganisms. First, a sequence of digital image preprocessing and processing steps is proposed for the treatment of microscopic images of a filamentous culture. The preprocessing step include band pass filtering by the Difference of Gaussians filter featuring a novel approach to the task of parameters tuning, as well as the optimization of image porosity and image objects separation quality. In the processing step, the resulting enhanced images are subject to morphological state characterization using a set of several standard and modified morphological parameters. Descriptions of morphological states of different complexity are then discussed varying from the standard set of mean values of parameters to the set of parameters in their full histogram of value frequencies (distribution) form. For such complex descriptions also new fashions of graphical representation of results without loss of information are compared. The potential of the proposed full description of morphological behavior of the culture is demonstrated using a set of microscopic images taken during an industrial antibiotics production cultivation using a microorganism belonging into the Streptomyces genus. Finally, the cluster analysis is proposed for further automatic quantitative classification and interpretation of complex description of metabolic states.Technology Agency of the Czech Republi

How Parents Perceive the Potential Risk of a Child-Dog Interaction

Dog attacks on children are a widespread problem, which can occur when parents fail to realise a potentially dangerous interaction between a dog and a child. The aim of the study was to evaluate the ability of parents to identify dangerous situations from several everyday child&ndash;dog interactions and to determine whether the participants connected these situations to a particular breed of dog. Five sets of photographs depicting potentially dangerous interactions from everyday situations between children and three dogs (one of each breed) were presented via an online survey to parents of children no more than 6 years old. Data from 207 respondents were analysed using proc GLIMMIX in SAS program, version 9.3. The probability of risk assessment varied according to dog breed (p &lt; 0.001) as well as to the depicted situation (p &lt; 0.001). Results indicated that Labrador Retriever was considered the least likely of the three dogs to be involved in a dangerous dog-child interaction (with 49% predicting a dangerous interaction), followed by Parson Russell Terrier (63.2%) and American Pit Bull Terrier (65%). Participants considered one particular dog-child interaction named &lsquo;touching a bowl&rsquo; a dangerous interaction at a high rate (77.9%) when compared with the other presented situations, which were assessed as dangerous at rates of 48.4% to 56.5%. The breed of dog seems to be an influential factor when assessing a potentially dangerous outcome from a dog-child interaction. Contrary to our hypothesis, interactions involving the small dog (Russell Terrier) were rated more critically, similarly to those of the Pit Bull Terrier. These results suggest that even popular family dog breeds, such as Labrador Retrievers, should be treated with more caution

Factors influencing CRB test results

This contribution deals with simulation of fracture behaviour of specimens for CRB (cracked round bar) test. These specimens are used for accelerated testing of polymer materials’ performance for piping applications. The CRB test is one of the most effective methods of testing due to use of cyclic loading instead of more common static force. However, in some cases the CRB specimens’ fracture surfaces come out asymmetrical. With the use of FEM simulation of the crack propagation in CRB specimens, the influence of this asymmetry on the results of CRB test is investigated