The advent of microgrids in modern energy systems heralds a promising era of resilience,sustainability,and efficiency.Within the realm of grid-tied microgrids,the selection of an optimal optimization algorithm is crit...The advent of microgrids in modern energy systems heralds a promising era of resilience,sustainability,and efficiency.Within the realm of grid-tied microgrids,the selection of an optimal optimization algorithm is critical for effective energy management,particularly in economic dispatching.This study compares the performance of Particle Swarm Optimization(PSO)and Genetic Algorithms(GA)in microgrid energy management systems,implemented using MATLAB tools.Through a comprehensive review of the literature and sim-ulations conducted in MATLAB,the study analyzes performance metrics,convergence speed,and the overall efficacy of GA and PSO,with a focus on economic dispatching tasks.Notably,a significant distinction emerges between the cost curves generated by the two algo-rithms for microgrid operation,with the PSO algorithm consistently resulting in lower costs due to its effective economic dispatching capabilities.Specifically,the utilization of the PSO approach could potentially lead to substantial savings on the power bill,amounting to approximately$15.30 in this evaluation.Thefindings provide insights into the strengths and limitations of each algorithm within the complex dynamics of grid-tied microgrids,thereby assisting stakeholders and researchers in arriving at informed decisions.This study contributes to the discourse on sustainable energy management by offering actionable guidance for the advancement of grid-tied micro-grid technologies through MATLAB-implemented optimization algorithms.展开更多
In this paper, a hybrid predictive controller is proposed for a class of uncertain switched nonlinear systems based on high-order differential state observers and Lyapunov functions. The main idea is to design an outp...In this paper, a hybrid predictive controller is proposed for a class of uncertain switched nonlinear systems based on high-order differential state observers and Lyapunov functions. The main idea is to design an output feedback bounded controller and a predictive controller for each subsystem using high-order differential state observers and Lyapunov functions, to derive a suitable switched law to stabilize the closed-loop subsystem, and to provide an explicitly characterized set of initial conditions. For the whole switched system, based on the high-order differentiator, a suitable switched law is designed to ensure the whole closed-loop’s stability. The simulation results for a chemical process show the validity of the controller proposed in this paper.展开更多
The quantitative determination of heavy metals in aquatic products is of great importance for food security issues.Laser-induced breakdown spectroscopy(LIBS)has been used in a variety of foodstuff analysis,but is stil...The quantitative determination of heavy metals in aquatic products is of great importance for food security issues.Laser-induced breakdown spectroscopy(LIBS)has been used in a variety of foodstuff analysis,but is still limited by its low sensitivity when targeting trace heavy metals.In this work,we compare three sample enrichment methods,namely drying,carbonization,and ashing,for increasing detection sensitivity by LIBS analysis for Pb and Cr in oyster samples.The results demonstrate that carbonization can remove a significant amount of the contributions of organic elements C,H,N and O;meanwhile,the signals of the metallic elements such as Cu,Pb,Sr,Ca,Cr and Mg are enhanced by3–6 times after carbonization,and further enhanced by 5–9 times after ashing.Such enhancement is not only due to the more concentrated metallic elements in the sample compared to the dried ones,but also the unifying of the matter in carbonized and ashed samples from which higher plasma temperature and electron density are observed.This condition favors the detection of trace elements.According to the calibration curves with univariate and multivariate analysis,the ashing method is considered to be the best choice.The limits of detection of the ashing method are 0.52 mg kg-1 for Pb and0.08 mg kg-1 for Cr,which can detect the presence of heavy metals in the oysters exceeding the maximum limits of Pb and Cr required by the Chinese national standard.This method provides a promising application for the heavy metal contamination monitoring in the aquatic product industry.展开更多
Bow thrusters usually are hydraulic and mechanically driven engines,used for the positioning maneuvers of River and sea boats.The peculiarity of these systems operating on short time intervals is their low rate of use...Bow thrusters usually are hydraulic and mechanically driven engines,used for the positioning maneuvers of River and sea boats.The peculiarity of these systems operating on short time intervals is their low rate of use(approximately 2%)but requiring maximal power.The main purpose of the work is to propose an innovative electrical hybridization of the bow thruster for a river tugboat.This electrification solution enables the bow thruster to operate with no-emissions,reduced noise and is a subsystem of green ship.Main challenge is to manage high torque and low speed requirements of the bow thruster system during the positioning maneuvers,by adding a dynamic electrical storage system,based on high capacitance value Supercapacitors,and in association with the electrified propeller motor.The knowledge concerns hybrid electrification,involving new-technology elements,energy storage based on supercapacitors,the high amplitude low speed torque control strategy.With fully reversible electrical motorization,the propeller is able to operate for both direct-reverse ways of rotation.Proposed electrical solution would hence provide large expected benefits in terms of energy efficiency,compactness,weights,costs,and contribute to a more eco-friendly ship.Numerical simulation and first results on laboratory test bench validate the proposed electrification concept.展开更多
The wavelength modulation indices are measured based on harmonic amplitude ratio of 4famp/6famp (4famp and 6famp are the 4- and 6-th harmonic central peak amplitudes correspondingly) with the Doppler-free selective re...The wavelength modulation indices are measured based on harmonic amplitude ratio of 4famp/6famp (4famp and 6famp are the 4- and 6-th harmonic central peak amplitudes correspondingly) with the Doppler-free selective reflection modulation spectroscopy. The experiments for the 6S1/2(F = 4) → 6P3/2(F' = 5) transition of cesium D2 line with 30-MHz linewidth were carried out. The 4f- and 6f-harmonic signals were detected with two digital lock-in amplifiers separately. The maximum error for modulation indices measurement was ±0.1 within the range of m from 3 to 6. The non-linear modulation behaviour of an external cavity diode laser induced by voltage tuning was studied with this method. The method for modulation indices measurement does not require a solid etalon as usual for measuring the wavelength modulation depth and the absorption linewidth correspondingly.展开更多
Objective:Street-based female sex workers are more likely to practice unprotected sex with multiple partners increases their risk of infection with sexually transmitted diseases.This study was performed to evaluate th...Objective:Street-based female sex workers are more likely to practice unprotected sex with multiple partners increases their risk of infection with sexually transmitted diseases.This study was performed to evaluate the understanding of and risk factors for sexually transmitted diseases among street-based female sex workers.Methods:A survey consisted of a sociodemographic section and a health section was conducted from June to August in two consecutive years(2012-2013)using an anonymous questionnaire compiled by street-based female sex workers in the area of Florence(Central Italy).A descriptive analysis of sociodemographic,epidemiological,and anamnestic variables was performed using common methods for proportions;associations between variables were assessed using univariate and bivariate logistic regression.Results:Totally 122 street-based female sex workers(mean age,24.1 years;age range,17-45 years)were enrolled,and were from Europe(63.1%)(mainly from Romania[48.4%]and Albania[13.1%]),Africa(31.2%)(specifically Nigeria),and South America(5.7%).Of the 122 street-based female sex workers,63%were married/engaged and 37%were single.More than half had been living in Italy and Florence for more than 1 year;72.8%stated that they possessed a residence permit and the others were illegal migrants.Eighteen(15%)street-based female sex workers also worked in the industry in neighboring European countries.Their level of education was generally high:58.1%had completed secondary school(lower secondary school and upper secondary school).A total of 81.4%stated that they perceived an actual fear of contracting human immunodeficiency virus;in fact,43.3%had never been tested for any sexually transmitted diseases except for human immunodeficiency virus.Conclusion:Despite the long-time involvement of street-based female sex workers in the commercial sex industry,the large numbers of clients and a strong perception of concerns about sexually transmitted diseases.This study confirms a low rate of condom use and blood screening,and corresponding science education and health screening efforts need to be strengthened in this high risk population.展开更多
Polylactic acid(PLA)-graphene nanocomposites have attracted significant attention in the biomedical field because of their biodegradability,biocompatibility,and excellent mechanical properties.This review provides a c...Polylactic acid(PLA)-graphene nanocomposites have attracted significant attention in the biomedical field because of their biodegradability,biocompatibility,and excellent mechanical properties.This review provides a comprehensive summary of the recent developments in the biomedical applications of PLA/graphene nanocomposites.The discussed applications include tissue engineering,drug delivery,biomedical imaging and sensing,antimicrobial and anticancer treatments,and photothermal and photodynamic therapies.The properties and synthesis of these nanocomposites are also addressed.This review shows that although significant advancements have been made in the development of biomedical applications for PLA/graphene nanocomposites,further research is still required to overcome the existing challenges and limitations,such as improving biocompatibility and biodegradability and optimizing synthesis and processing methods.Despite these challenges,the potential of PLA/graphene nanocomposites in the biomedical field is significant and holds promise for future advancements.展开更多
文摘The advent of microgrids in modern energy systems heralds a promising era of resilience,sustainability,and efficiency.Within the realm of grid-tied microgrids,the selection of an optimal optimization algorithm is critical for effective energy management,particularly in economic dispatching.This study compares the performance of Particle Swarm Optimization(PSO)and Genetic Algorithms(GA)in microgrid energy management systems,implemented using MATLAB tools.Through a comprehensive review of the literature and sim-ulations conducted in MATLAB,the study analyzes performance metrics,convergence speed,and the overall efficacy of GA and PSO,with a focus on economic dispatching tasks.Notably,a significant distinction emerges between the cost curves generated by the two algo-rithms for microgrid operation,with the PSO algorithm consistently resulting in lower costs due to its effective economic dispatching capabilities.Specifically,the utilization of the PSO approach could potentially lead to substantial savings on the power bill,amounting to approximately$15.30 in this evaluation.Thefindings provide insights into the strengths and limitations of each algorithm within the complex dynamics of grid-tied microgrids,thereby assisting stakeholders and researchers in arriving at informed decisions.This study contributes to the discourse on sustainable energy management by offering actionable guidance for the advancement of grid-tied micro-grid technologies through MATLAB-implemented optimization algorithms.
文摘In this paper, a hybrid predictive controller is proposed for a class of uncertain switched nonlinear systems based on high-order differential state observers and Lyapunov functions. The main idea is to design an output feedback bounded controller and a predictive controller for each subsystem using high-order differential state observers and Lyapunov functions, to derive a suitable switched law to stabilize the closed-loop subsystem, and to provide an explicitly characterized set of initial conditions. For the whole switched system, based on the high-order differentiator, a suitable switched law is designed to ensure the whole closed-loop’s stability. The simulation results for a chemical process show the validity of the controller proposed in this paper.
基金supported by the National Key Research and Development Program of China(No.2019YFD0901701)National Natural Science Foundation of China(Nos.12174359and 61975190)Provincial Key Research and Development Program of Shandong,China(No.2019GHZ010)。
文摘The quantitative determination of heavy metals in aquatic products is of great importance for food security issues.Laser-induced breakdown spectroscopy(LIBS)has been used in a variety of foodstuff analysis,but is still limited by its low sensitivity when targeting trace heavy metals.In this work,we compare three sample enrichment methods,namely drying,carbonization,and ashing,for increasing detection sensitivity by LIBS analysis for Pb and Cr in oyster samples.The results demonstrate that carbonization can remove a significant amount of the contributions of organic elements C,H,N and O;meanwhile,the signals of the metallic elements such as Cu,Pb,Sr,Ca,Cr and Mg are enhanced by3–6 times after carbonization,and further enhanced by 5–9 times after ashing.Such enhancement is not only due to the more concentrated metallic elements in the sample compared to the dried ones,but also the unifying of the matter in carbonized and ashed samples from which higher plasma temperature and electron density are observed.This condition favors the detection of trace elements.According to the calibration curves with univariate and multivariate analysis,the ashing method is considered to be the best choice.The limits of detection of the ashing method are 0.52 mg kg-1 for Pb and0.08 mg kg-1 for Cr,which can detect the presence of heavy metals in the oysters exceeding the maximum limits of Pb and Cr required by the Chinese national standard.This method provides a promising application for the heavy metal contamination monitoring in the aquatic product industry.
文摘Bow thrusters usually are hydraulic and mechanically driven engines,used for the positioning maneuvers of River and sea boats.The peculiarity of these systems operating on short time intervals is their low rate of use(approximately 2%)but requiring maximal power.The main purpose of the work is to propose an innovative electrical hybridization of the bow thruster for a river tugboat.This electrification solution enables the bow thruster to operate with no-emissions,reduced noise and is a subsystem of green ship.Main challenge is to manage high torque and low speed requirements of the bow thruster system during the positioning maneuvers,by adding a dynamic electrical storage system,based on high capacitance value Supercapacitors,and in association with the electrified propeller motor.The knowledge concerns hybrid electrification,involving new-technology elements,energy storage based on supercapacitors,the high amplitude low speed torque control strategy.With fully reversible electrical motorization,the propeller is able to operate for both direct-reverse ways of rotation.Proposed electrical solution would hence provide large expected benefits in terms of energy efficiency,compactness,weights,costs,and contribute to a more eco-friendly ship.Numerical simulation and first results on laboratory test bench validate the proposed electrification concept.
基金This work was supported in part by the National Natural Science Foundation of China (Grant No. 10174047, 60078009) Natural Science Foundation of Shanxi Province.
文摘The wavelength modulation indices are measured based on harmonic amplitude ratio of 4famp/6famp (4famp and 6famp are the 4- and 6-th harmonic central peak amplitudes correspondingly) with the Doppler-free selective reflection modulation spectroscopy. The experiments for the 6S1/2(F = 4) → 6P3/2(F' = 5) transition of cesium D2 line with 30-MHz linewidth were carried out. The 4f- and 6f-harmonic signals were detected with two digital lock-in amplifiers separately. The maximum error for modulation indices measurement was ±0.1 within the range of m from 3 to 6. The non-linear modulation behaviour of an external cavity diode laser induced by voltage tuning was studied with this method. The method for modulation indices measurement does not require a solid etalon as usual for measuring the wavelength modulation depth and the absorption linewidth correspondingly.
文摘Objective:Street-based female sex workers are more likely to practice unprotected sex with multiple partners increases their risk of infection with sexually transmitted diseases.This study was performed to evaluate the understanding of and risk factors for sexually transmitted diseases among street-based female sex workers.Methods:A survey consisted of a sociodemographic section and a health section was conducted from June to August in two consecutive years(2012-2013)using an anonymous questionnaire compiled by street-based female sex workers in the area of Florence(Central Italy).A descriptive analysis of sociodemographic,epidemiological,and anamnestic variables was performed using common methods for proportions;associations between variables were assessed using univariate and bivariate logistic regression.Results:Totally 122 street-based female sex workers(mean age,24.1 years;age range,17-45 years)were enrolled,and were from Europe(63.1%)(mainly from Romania[48.4%]and Albania[13.1%]),Africa(31.2%)(specifically Nigeria),and South America(5.7%).Of the 122 street-based female sex workers,63%were married/engaged and 37%were single.More than half had been living in Italy and Florence for more than 1 year;72.8%stated that they possessed a residence permit and the others were illegal migrants.Eighteen(15%)street-based female sex workers also worked in the industry in neighboring European countries.Their level of education was generally high:58.1%had completed secondary school(lower secondary school and upper secondary school).A total of 81.4%stated that they perceived an actual fear of contracting human immunodeficiency virus;in fact,43.3%had never been tested for any sexually transmitted diseases except for human immunodeficiency virus.Conclusion:Despite the long-time involvement of street-based female sex workers in the commercial sex industry,the large numbers of clients and a strong perception of concerns about sexually transmitted diseases.This study confirms a low rate of condom use and blood screening,and corresponding science education and health screening efforts need to be strengthened in this high risk population.
基金Department of Science and Innovation,South Africa,Grant/Award Number:C6A0058National Research Foundation,Grant/Award Number:116083/138768。
文摘Polylactic acid(PLA)-graphene nanocomposites have attracted significant attention in the biomedical field because of their biodegradability,biocompatibility,and excellent mechanical properties.This review provides a comprehensive summary of the recent developments in the biomedical applications of PLA/graphene nanocomposites.The discussed applications include tissue engineering,drug delivery,biomedical imaging and sensing,antimicrobial and anticancer treatments,and photothermal and photodynamic therapies.The properties and synthesis of these nanocomposites are also addressed.This review shows that although significant advancements have been made in the development of biomedical applications for PLA/graphene nanocomposites,further research is still required to overcome the existing challenges and limitations,such as improving biocompatibility and biodegradability and optimizing synthesis and processing methods.Despite these challenges,the potential of PLA/graphene nanocomposites in the biomedical field is significant and holds promise for future advancements.
