The dimensional accuracy of machined parts is strongly influenced by the thermal behavior of machine tools (MT). Minimizing this influence represents a key objective for any modern manufacturing industry. Thermally in...The dimensional accuracy of machined parts is strongly influenced by the thermal behavior of machine tools (MT). Minimizing this influence represents a key objective for any modern manufacturing industry. Thermally induced positioning error compensation remains the most effective and practical method in this context. However, the efficiency of the compensation process depends on the quality of the model used to predict the thermal errors. The model should consistently reflect the relationships between temperature distribution in the MT structure and thermally induced positioning errors. A judicious choice of the number and location of temperature sensitive points to represent heat distribution is a key factor for robust thermal error modeling. Therefore, in this paper, the temperature sensitive points are selected following a structured thermomechanical analysis carried out to evaluate the effects of various temperature gradients on MT structure deformation intensity. The MT thermal behavior is first modeled using finite element method and validated by various experimentally measured temperature fields using temperature sensors and thermal imaging. MT Thermal behavior validation shows a maximum error of less than 10% when comparing the numerical estimations with the experimental results even under changing operation conditions. The numerical model is used through several series of simulations carried out using varied working condition to explore possible relationships between temperature distribution and thermal deformation characteristics to select the most appropriate temperature sensitive points that will be considered for building an empirical prediction model for thermal errors as function of MT thermal state. Validation tests achieved using an artificial neural network based simplified model confirmed the efficiency of the proposed temperature sensitive points allowing the prediction of the thermally induced errors with an accuracy greater than 90%.展开更多
Intensive fish farming has an excessive prevalence of infection and is typically controlled by the administration of antibiotics.Although amalgamated antibiotics are a relatively novel therapeutic idea and more effect...Intensive fish farming has an excessive prevalence of infection and is typically controlled by the administration of antibiotics.Although amalgamated antibiotics are a relatively novel therapeutic idea and more effective than traditional antibiotic monotherapy,they can also have a toxic effect on the fish body when it is administered abruptly.This study investigated the cyto-genotoxic effects on erythrocytes and histo-architectural malformations in the liver and kidneys of stinging catfish(Heteropneustes fossilis)in relation to Enrocip plus use as an amalgamated antibiotic agent.The experimental fish with an initial average weight of 17.38±1.94 g were divided into four treatment groups with antibiotic doses:according to the recommendation of the manufacturer 0.167 mg/ml Enrocip plus was used as a standard dose(x)and it was treated as T3,while 0%of the standard dose(0×mg/ml),1/2×(0.083 mg/ml),and 2×(0.333 mg/ml)were treated as T1,T2 and T4,respectively for a period of 30 days.The observed erythrocyte cellular deformities(ECD)were twin,tear-drop,serrated,tail budded and de-membranated cells,whereas the erythrocyte nuclear deformities(END)were a nuclear bridge,bi-nucleus,nuclear termination,karyopyknosis,and micronucleus at different concentrations of Enrocip plus.Both ECD and END percentages experienced the interaction of antibiotic dose and exposure time,and were significantly different(P<0.01).Significant changes in hepatocytes,mild to severe necrosis,vacuole formation,and hepatopancreas damage were also observed in the liver of the treated fish whereas highly degraded renal tubules and hematopoietic tissue,glomerular occlusion,and vacuolation were evident in the kidneys.The current investigation fully emphasizes the adverse effects of amalgamated antibiotics on the cytogenotoxicity and the histomorphology of the kidneys and liver of fish.Thus,the use of an amalgamated antibiotic in aquaculture must be carefully evaluated.展开更多
文摘The dimensional accuracy of machined parts is strongly influenced by the thermal behavior of machine tools (MT). Minimizing this influence represents a key objective for any modern manufacturing industry. Thermally induced positioning error compensation remains the most effective and practical method in this context. However, the efficiency of the compensation process depends on the quality of the model used to predict the thermal errors. The model should consistently reflect the relationships between temperature distribution in the MT structure and thermally induced positioning errors. A judicious choice of the number and location of temperature sensitive points to represent heat distribution is a key factor for robust thermal error modeling. Therefore, in this paper, the temperature sensitive points are selected following a structured thermomechanical analysis carried out to evaluate the effects of various temperature gradients on MT structure deformation intensity. The MT thermal behavior is first modeled using finite element method and validated by various experimentally measured temperature fields using temperature sensors and thermal imaging. MT Thermal behavior validation shows a maximum error of less than 10% when comparing the numerical estimations with the experimental results even under changing operation conditions. The numerical model is used through several series of simulations carried out using varied working condition to explore possible relationships between temperature distribution and thermal deformation characteristics to select the most appropriate temperature sensitive points that will be considered for building an empirical prediction model for thermal errors as function of MT thermal state. Validation tests achieved using an artificial neural network based simplified model confirmed the efficiency of the proposed temperature sensitive points allowing the prediction of the thermally induced errors with an accuracy greater than 90%.
文摘Intensive fish farming has an excessive prevalence of infection and is typically controlled by the administration of antibiotics.Although amalgamated antibiotics are a relatively novel therapeutic idea and more effective than traditional antibiotic monotherapy,they can also have a toxic effect on the fish body when it is administered abruptly.This study investigated the cyto-genotoxic effects on erythrocytes and histo-architectural malformations in the liver and kidneys of stinging catfish(Heteropneustes fossilis)in relation to Enrocip plus use as an amalgamated antibiotic agent.The experimental fish with an initial average weight of 17.38±1.94 g were divided into four treatment groups with antibiotic doses:according to the recommendation of the manufacturer 0.167 mg/ml Enrocip plus was used as a standard dose(x)and it was treated as T3,while 0%of the standard dose(0×mg/ml),1/2×(0.083 mg/ml),and 2×(0.333 mg/ml)were treated as T1,T2 and T4,respectively for a period of 30 days.The observed erythrocyte cellular deformities(ECD)were twin,tear-drop,serrated,tail budded and de-membranated cells,whereas the erythrocyte nuclear deformities(END)were a nuclear bridge,bi-nucleus,nuclear termination,karyopyknosis,and micronucleus at different concentrations of Enrocip plus.Both ECD and END percentages experienced the interaction of antibiotic dose and exposure time,and were significantly different(P<0.01).Significant changes in hepatocytes,mild to severe necrosis,vacuole formation,and hepatopancreas damage were also observed in the liver of the treated fish whereas highly degraded renal tubules and hematopoietic tissue,glomerular occlusion,and vacuolation were evident in the kidneys.The current investigation fully emphasizes the adverse effects of amalgamated antibiotics on the cytogenotoxicity and the histomorphology of the kidneys and liver of fish.Thus,the use of an amalgamated antibiotic in aquaculture must be carefully evaluated.
