This paper presents the design of a novel trajectory tracking control strategy and the development of a mathematical model for a non-holonomic differential-drive wheeled mobile robot. The proposed control system utilizes a dual-loop approach, where the inner loop controls the dynamics by employing Adaptive Fuzzy Sliding Mode Control (AFSMC), and the outer loop, handles kinematics by utilizing an Adaptive Neuro-Fuzzy Inference System ;(ANFIS). The ANFIS is employed to minimize the error between the actual and desired velocities, providing a desired input for the inner loop. Meanwhile, the AFSMC is used to effectively control the system dynamics. The use of these dual-loop controllers considerably improves the system’s overall efficiency. The inner controller compensates for dynamic disturbances, while the outer controller manages velocity errors. We integrate the actuator dynamics and the chopper effect of the wheels in the dynamics modeling, which helps to increase the models accuracy. MATLAB was used to implement the controller, while circular and eight-shaped trajectories were generated to assess the performance of the proposed controller. In addition, a comparative analysis of different controllers such as PID, SMC, AFSMC, and AFSMC with ANFIS was presented. The simulations were conducted under uncertainties, and the proposed controller is better than other controllers at tracking desired trajectories. The Lyapunov stability analysis is employed to verify the stability of the proposed controller. This paper shows that the proposed dual-loop controller is stable and more robust to internal parameter variation and external disturbance for the examined system. In general, the AFSMC with ANFIS is superior in trajectory tracking for the examined system compared to other controllers.
{"title":"Design of an Adaptive Fuzzy Sliding Mode Control with Neuro-Fuzzy system for control of a differential drive wheeled mobile robot","authors":"Aderajew Ashagrie Tilahun, Tilahun Weldcherkos Desta, Ayodeji Olalekan Salau, Lebsework Negash","doi":"10.1080/23311916.2023.2276517","DOIUrl":"https://doi.org/10.1080/23311916.2023.2276517","url":null,"abstract":"This paper presents the design of a novel trajectory tracking control strategy and the development of a mathematical model for a non-holonomic differential-drive wheeled mobile robot. The proposed control system utilizes a dual-loop approach, where the inner loop controls the dynamics by employing Adaptive Fuzzy Sliding Mode Control (AFSMC), and the outer loop, handles kinematics by utilizing an Adaptive Neuro-Fuzzy Inference System ;(ANFIS). The ANFIS is employed to minimize the error between the actual and desired velocities, providing a desired input for the inner loop. Meanwhile, the AFSMC is used to effectively control the system dynamics. The use of these dual-loop controllers considerably improves the system’s overall efficiency. The inner controller compensates for dynamic disturbances, while the outer controller manages velocity errors. We integrate the actuator dynamics and the chopper effect of the wheels in the dynamics modeling, which helps to increase the models accuracy. MATLAB was used to implement the controller, while circular and eight-shaped trajectories were generated to assess the performance of the proposed controller. In addition, a comparative analysis of different controllers such as PID, SMC, AFSMC, and AFSMC with ANFIS was presented. The simulations were conducted under uncertainties, and the proposed controller is better than other controllers at tracking desired trajectories. The Lyapunov stability analysis is employed to verify the stability of the proposed controller. This paper shows that the proposed dual-loop controller is stable and more robust to internal parameter variation and external disturbance for the examined system. In general, the AFSMC with ANFIS is superior in trajectory tracking for the examined system compared to other controllers.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"117 50","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135138035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-05DOI: 10.1080/23311916.2023.2272361
Krishnaraj Chadaga, Srikanth Prabhu, Vivekananda Bhat, Niranjana Sampathila, Shashikiran Umakanth, Rajagopala Chadaga, G. S. Shashi Kumar, K. S. Swathi
Millions of lives have been impacted by COVID-19, which has spread rapidly. Several vaccines have been developed to curb the severe prognosis induced by the virus. However, a part of the population (elderly and patients with coexisting conditions) is still at risk. It is crucial to identify these patients early since appropriate treatments can be provided to them to prevent the onset of severe symptoms such as breathlessness and hypoxia. Hence, this study utilizes machine learning and explainable artificial intelligence (XAI) to predict COVID-19 severity using biochemical, haematological and inflammatory markers. The patients are grouped into three classes: mild, moderate and severe. Four nature-inspired techniques have been utilized to select the best markers. The final stacked model obtained a maximum accuracy of 84. Demystifying the models has been done using four XAI techniques, including Shapley additive values (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME). Lactate dehydrogenase (LDH), albumin, D-Dimer, c-reactive protein (CRP) and lymphocytes were considered important, according to them. The classifiers can be utilized as a prognostic decision support framework to aid the medical personnel in classifying COVID-19 patients.
{"title":"An explainable multi-class decision support framework to predict COVID-19 prognosis utilizing biomarkers","authors":"Krishnaraj Chadaga, Srikanth Prabhu, Vivekananda Bhat, Niranjana Sampathila, Shashikiran Umakanth, Rajagopala Chadaga, G. S. Shashi Kumar, K. S. Swathi","doi":"10.1080/23311916.2023.2272361","DOIUrl":"https://doi.org/10.1080/23311916.2023.2272361","url":null,"abstract":"Millions of lives have been impacted by COVID-19, which has spread rapidly. Several vaccines have been developed to curb the severe prognosis induced by the virus. However, a part of the population (elderly and patients with coexisting conditions) is still at risk. It is crucial to identify these patients early since appropriate treatments can be provided to them to prevent the onset of severe symptoms such as breathlessness and hypoxia. Hence, this study utilizes machine learning and explainable artificial intelligence (XAI) to predict COVID-19 severity using biochemical, haematological and inflammatory markers. The patients are grouped into three classes: mild, moderate and severe. Four nature-inspired techniques have been utilized to select the best markers. The final stacked model obtained a maximum accuracy of 84. Demystifying the models has been done using four XAI techniques, including Shapley additive values (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME). Lactate dehydrogenase (LDH), albumin, D-Dimer, c-reactive protein (CRP) and lymphocytes were considered important, according to them. The classifiers can be utilized as a prognostic decision support framework to aid the medical personnel in classifying COVID-19 patients.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"72 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135725956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-05DOI: 10.1080/23311916.2023.2272342
Arjun Chouriya, Ajay Kushwah, V. K. Tewari, Chanchal Gupta, Prateek Shrivastava, Vijay Mahore
The power take-off (PTO) torque measuring system was designed, which includes a torque transducer and a digital wireless system to receive, process, and display the observed PTO torque. A dynamic PTO torque transducer was developed using strain gauges to fit in between the PTO shaft of the tractor and the universal shaft of the implement and simulated using SolidWorks software with 1000 Nm twisting moment along with 100 N load. To transmit torque signals from the revolving PTO shaft, an embedded system was developed. The embedded system was tested in the laboratory and under actual field conditions. The digital wireless embedded system comprised an amplifier cum analog to digital converter to amplify the received signal from the torque transducer and convert it into a digital value. A microcontroller processes the digital value given by the amplifier, and radio frequency (RF) receiver module was mounted on the Xbee explorer to receive the transmitted data from the RF module of signal processing and transmitter unit. The developed system was tested under field conditions, and data were compared with the existing commercial torque transducer. The results showed that the relative deviation between the observed mean PTO torque values obtained from the developed torque transducer and that from the existing torque transducer was 8.57% and 9.06% at 2.5 km/h and 3.5 km/h, respectively.
{"title":"Development of PTO torque transducer based on an embedded digital wireless system for the 2WD tractor","authors":"Arjun Chouriya, Ajay Kushwah, V. K. Tewari, Chanchal Gupta, Prateek Shrivastava, Vijay Mahore","doi":"10.1080/23311916.2023.2272342","DOIUrl":"https://doi.org/10.1080/23311916.2023.2272342","url":null,"abstract":"The power take-off (PTO) torque measuring system was designed, which includes a torque transducer and a digital wireless system to receive, process, and display the observed PTO torque. A dynamic PTO torque transducer was developed using strain gauges to fit in between the PTO shaft of the tractor and the universal shaft of the implement and simulated using SolidWorks software with 1000 Nm twisting moment along with 100 N load. To transmit torque signals from the revolving PTO shaft, an embedded system was developed. The embedded system was tested in the laboratory and under actual field conditions. The digital wireless embedded system comprised an amplifier cum analog to digital converter to amplify the received signal from the torque transducer and convert it into a digital value. A microcontroller processes the digital value given by the amplifier, and radio frequency (RF) receiver module was mounted on the Xbee explorer to receive the transmitted data from the RF module of signal processing and transmitter unit. The developed system was tested under field conditions, and data were compared with the existing commercial torque transducer. The results showed that the relative deviation between the observed mean PTO torque values obtained from the developed torque transducer and that from the existing torque transducer was 8.57% and 9.06% at 2.5 km/h and 3.5 km/h, respectively.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"75 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135726252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-02DOI: 10.1080/23311916.2023.2269654
Aneesh Mathew, P. Sarwesh, Sumit Khandelwal, Padala Raja Shekar, Joseph Omeiza Alao, Hazem Ghassan Abdo, Hussein Almohamad, Ahmed Abdullah Al Dughairi
The Urban Heat Island (UHI) effect is a phenomenon where urban areas experience higher temperatures than surrounding rural areas. In these issues, enhanced air or surface temperature is one of the major issues that led to the UHI phenomenon. In this article, we come up with a study on the diurnal UHI effect caused in Jaipur city, India, and surrounding areas of Jaipur. In-situ temperature monitoring has been carried out at seven dispersed locations to properly understand and evaluate the effects of surface UHI (SUHI) and atmospheric UHI (AUHI), as well as to assess the thermal profile of diverse land surfaces in Jaipur. With the use of satellite data, the intensity of AUHI and SUHI has been determined between 10.30 a.m. and 10.30 p.m. The observations point out that positive AUHI intensity (AUHII) exists at many locations, irrespective of time periods. During the day period, negative SUHI intensity (SUHII) was noticed at many locations, whereas during the night period, positive SUHII was noticed. According to our observations, AUHI and SUHI have a direct correlation at night but a negative or inverse correlation during the day. That is, AUHI was active both during the day and at night. Various land surfaces play a significant role in contrasting the diurnal UHI effect. This study evaluates the potential of remotely sensed data in monitoring the UHI effect and provides recommendations for urban planners and policymakers to mitigate the UHI effect in the city of Jaipur.
{"title":"Thermal dynamics of Jaipur: Analyzing urban heat island effects using in-situ and remotely sensed data","authors":"Aneesh Mathew, P. Sarwesh, Sumit Khandelwal, Padala Raja Shekar, Joseph Omeiza Alao, Hazem Ghassan Abdo, Hussein Almohamad, Ahmed Abdullah Al Dughairi","doi":"10.1080/23311916.2023.2269654","DOIUrl":"https://doi.org/10.1080/23311916.2023.2269654","url":null,"abstract":"The Urban Heat Island (UHI) effect is a phenomenon where urban areas experience higher temperatures than surrounding rural areas. In these issues, enhanced air or surface temperature is one of the major issues that led to the UHI phenomenon. In this article, we come up with a study on the diurnal UHI effect caused in Jaipur city, India, and surrounding areas of Jaipur. In-situ temperature monitoring has been carried out at seven dispersed locations to properly understand and evaluate the effects of surface UHI (SUHI) and atmospheric UHI (AUHI), as well as to assess the thermal profile of diverse land surfaces in Jaipur. With the use of satellite data, the intensity of AUHI and SUHI has been determined between 10.30 a.m. and 10.30 p.m. The observations point out that positive AUHI intensity (AUHII) exists at many locations, irrespective of time periods. During the day period, negative SUHI intensity (SUHII) was noticed at many locations, whereas during the night period, positive SUHII was noticed. According to our observations, AUHI and SUHI have a direct correlation at night but a negative or inverse correlation during the day. That is, AUHI was active both during the day and at night. Various land surfaces play a significant role in contrasting the diurnal UHI effect. This study evaluates the potential of remotely sensed data in monitoring the UHI effect and provides recommendations for urban planners and policymakers to mitigate the UHI effect in the city of Jaipur.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"30 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135972994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to develop a queuing model at the Commercial Bank of Ethiopia to improve the service quality perceived by customers using a simulation tool. Performance variables that were considered when developing this model are the average waiting time for a client to get service, customer arrival rates, and service time. After the identification of the problem, the service quality of the bank is assessed using a questionnaire that was prepared in SERVQUAL format. The filled-out and returned questionnaires were analyzed using SPSS, and the results show that the service quality of the bank was deemed very low. The recorded data was then ultimately used as a basis for the determination of arrival, service rates, and the distribution function in the simulation input analyzer. The distribution function determined was used as an input for the development of the existing queue model, and based on that, scientific scenarios are adopted from scientific research and further observations at the bank are added to show enhancement of the existing model. The study used four scenarios to test the response group, and one scenario was selected as the best. This has been identified by adding a server to the counters where there is less utilization, that is, servers four and five. As a result, the waiting time has been minimized by 20 minutes under server four and by 83.4 minutes under server five. Also, the number of customers served per day can be increased from 1048 to 1168, which is 11.45% improvement.
{"title":"Modeling and simulation of queuing system to improve service quality at commercial bank of Ethiopia","authors":"Tamrat Yifter, Melkamu Mengstenew, Semehar Yoseph, Wongel Moges","doi":"10.1080/23311916.2023.2274522","DOIUrl":"https://doi.org/10.1080/23311916.2023.2274522","url":null,"abstract":"This study aims to develop a queuing model at the Commercial Bank of Ethiopia to improve the service quality perceived by customers using a simulation tool. Performance variables that were considered when developing this model are the average waiting time for a client to get service, customer arrival rates, and service time. After the identification of the problem, the service quality of the bank is assessed using a questionnaire that was prepared in SERVQUAL format. The filled-out and returned questionnaires were analyzed using SPSS, and the results show that the service quality of the bank was deemed very low. The recorded data was then ultimately used as a basis for the determination of arrival, service rates, and the distribution function in the simulation input analyzer. The distribution function determined was used as an input for the development of the existing queue model, and based on that, scientific scenarios are adopted from scientific research and further observations at the bank are added to show enhancement of the existing model. The study used four scenarios to test the response group, and one scenario was selected as the best. This has been identified by adding a server to the counters where there is less utilization, that is, servers four and five. As a result, the waiting time has been minimized by 20 minutes under server four and by 83.4 minutes under server five. Also, the number of customers served per day can be increased from 1048 to 1168, which is 11.45% improvement.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"229 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135974857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-02DOI: 10.1080/23311916.2023.2274534
M.S.K. Tony Suryo Utomo, Ir. Eflita Yohana, Bramantya Krisna, M. Farkhan Dwinanda, Mohammad Tauviqirrahman, Kwang-Hwan Choi
Because a variety of fuels can be burned during the combustion process, CFB boilers have a very wide range of applications in coal-fired power plants. The uneven distribution of homogeneity between the air and the particles and the large volume fraction in some locations could result in erosion of the furnace walls. In order to decrease the impacts of erosion, the ring baffle feature is added to the furnace wall. In order to compare data variations in the form of ring baffle depth with variations of 0.15 m, 0.3 m, and 0.45 m as well as the number of ring baffles 1 and 2, the CFD approach is utilized. The factors tested included pressure drop distribution, particle volume fraction distribution, particle axial and radial velocity distribution, and shear stress. With a maximum value of 0.012 for the volume percent, the variation of two ring baffles with a depth of 0.3 m each offered the best results in terms of homogeneity inside the CFB of the boiler. Additionally, a pressure decrease of 7.38 kPa was seen due to the maximum axial and radial speeds that were measured at the ring baffle, which were 27.1 m/s and 2.46 m/s, respectively. Additionally, the furnace wall can avoid probable erosion thanks to the shear stress contours, which mirror the volume percentage of particles.
{"title":"Effect of ring baffle on erosion in circulating fluidized bed boiler","authors":"M.S.K. Tony Suryo Utomo, Ir. Eflita Yohana, Bramantya Krisna, M. Farkhan Dwinanda, Mohammad Tauviqirrahman, Kwang-Hwan Choi","doi":"10.1080/23311916.2023.2274534","DOIUrl":"https://doi.org/10.1080/23311916.2023.2274534","url":null,"abstract":"Because a variety of fuels can be burned during the combustion process, CFB boilers have a very wide range of applications in coal-fired power plants. The uneven distribution of homogeneity between the air and the particles and the large volume fraction in some locations could result in erosion of the furnace walls. In order to decrease the impacts of erosion, the ring baffle feature is added to the furnace wall. In order to compare data variations in the form of ring baffle depth with variations of 0.15 m, 0.3 m, and 0.45 m as well as the number of ring baffles 1 and 2, the CFD approach is utilized. The factors tested included pressure drop distribution, particle volume fraction distribution, particle axial and radial velocity distribution, and shear stress. With a maximum value of 0.012 for the volume percent, the variation of two ring baffles with a depth of 0.3 m each offered the best results in terms of homogeneity inside the CFB of the boiler. Additionally, a pressure decrease of 7.38 kPa was seen due to the maximum axial and radial speeds that were measured at the ring baffle, which were 27.1 m/s and 2.46 m/s, respectively. Additionally, the furnace wall can avoid probable erosion thanks to the shear stress contours, which mirror the volume percentage of particles.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"106 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135934976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-31DOI: 10.1080/23311916.2023.2269659
John E. Sani, George Moses, Shehu Musa
The effect of coconut shell biochar on pH, cation exchange capacity (CEC), sesquioxides and residual total petroleum hydrocarbon (TPH) of a crude oil contaminated soil was investigated. Raw coconut shells were carbonized in a muffle furnace at 400°C for 2 hours and chemically activated in sulphuric acid solution for 18 hours to produce coconut shell activated carbon (CSAC). The CSAC and crude oil-contaminated soil from Kaduna Refining and Petrochemical Company had their physicochemical properties determined. Six sets of CSAC- soil mixtures containing 1%, 1.5%, 2%, 2.5%, 3% and 3.5% CSAC content to undergo remediation for 36 days. The pH, cation exchange capacity (CEC) and total petroleum hydrocarbon (TPH) degradation increase with higher CSAC content while sesquioxides composition slightly decreases with CSAC addition. A significant reduction in TPH from (2045 to 447) mg/kg was achieved with peak TPH degradation of 78.14% at 3.5% CSAC content. Therefore, CSAC significantly enhances the adsorption and degradation of petroleum hydrocarbons in the contaminated soil.
{"title":"Physicochemical evaluation of coconut shell biochar remediation effect on crude oil contaminated soil","authors":"John E. Sani, George Moses, Shehu Musa","doi":"10.1080/23311916.2023.2269659","DOIUrl":"https://doi.org/10.1080/23311916.2023.2269659","url":null,"abstract":"The effect of coconut shell biochar on pH, cation exchange capacity (CEC), sesquioxides and residual total petroleum hydrocarbon (TPH) of a crude oil contaminated soil was investigated. Raw coconut shells were carbonized in a muffle furnace at 400°C for 2 hours and chemically activated in sulphuric acid solution for 18 hours to produce coconut shell activated carbon (CSAC). The CSAC and crude oil-contaminated soil from Kaduna Refining and Petrochemical Company had their physicochemical properties determined. Six sets of CSAC- soil mixtures containing 1%, 1.5%, 2%, 2.5%, 3% and 3.5% CSAC content to undergo remediation for 36 days. The pH, cation exchange capacity (CEC) and total petroleum hydrocarbon (TPH) degradation increase with higher CSAC content while sesquioxides composition slightly decreases with CSAC addition. A significant reduction in TPH from (2045 to 447) mg/kg was achieved with peak TPH degradation of 78.14% at 3.5% CSAC content. Therefore, CSAC significantly enhances the adsorption and degradation of petroleum hydrocarbons in the contaminated soil.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"169 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135928894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-31DOI: 10.1080/23311916.2023.2274548
W. Khraisat
The effects of quasi-static strain rates on the tensile properties of two commercial ferrite-martensite dual-phase DP 600 and DP 800 steels were investigated using strip-shaped samples. The investigation was done by uniaxial tensile tests, covering applicable quasi-static strain rates. The two dual-phase steels show positive strain rate sensitivity. It is found that, as the flow stress increases, the strain-rate sensitivity exponent m decreases. The drop in the strain-rate sensitivity exponent m with strain is largely attributed to the decreased true strain rate caused by the increased instantaneous length of the specimen as the deformation progresses. To better describe the flow behavior of DP steels, a relationship combining the effect of both strain hardening exponent n and strain-rate sensitivity exponent m on the slope of the stress-strain is correlated. A good agreement between the extended Hollomon model and experimental tensile test data from stress-strain measurements is found.
{"title":"Strain hardening exponent and strain rate sensitivity exponent of dual-phase steels at quasi-static strain rates during tensile testing","authors":"W. Khraisat","doi":"10.1080/23311916.2023.2274548","DOIUrl":"https://doi.org/10.1080/23311916.2023.2274548","url":null,"abstract":"The effects of quasi-static strain rates on the tensile properties of two commercial ferrite-martensite dual-phase DP 600 and DP 800 steels were investigated using strip-shaped samples. The investigation was done by uniaxial tensile tests, covering applicable quasi-static strain rates. The two dual-phase steels show positive strain rate sensitivity. It is found that, as the flow stress increases, the strain-rate sensitivity exponent m decreases. The drop in the strain-rate sensitivity exponent m with strain is largely attributed to the decreased true strain rate caused by the increased instantaneous length of the specimen as the deformation progresses. To better describe the flow behavior of DP steels, a relationship combining the effect of both strain hardening exponent n and strain-rate sensitivity exponent m on the slope of the stress-strain is correlated. A good agreement between the extended Hollomon model and experimental tensile test data from stress-strain measurements is found.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135928040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-30DOI: 10.1080/23311916.2023.2272354
Lifei Zhang, Lile Xie, Xinchun Lu
As the development of technology nodes proceeds to 7 nm node, chemical mechanical polishing (CMP) slurries for shallow trench isolation (STI) cannot fully meet the technical requirements. Higher goals are put forward for the polished surface qualities and the removal selectivity control. The polishing liquid exhibits issues such as easy agglomeration, removal rate of Si3N4 exceeding 50 Å/min, removal selectivity ratio of SiO2/Si3N4 below 20, increased surface scratches and roughness of SiO2 and Si3N4 after polishing exceeding 1 nm. Here, attention is given to studying the STI CMP process by introducing various ionic surfactants in ceria slurries, aiming to control removal rates, selectivity, as well as surface qualities. The findings of ball milling and settling tests were used as a starting point for choosing the effective surfactants, searching the minimal delamination phenomenon. Then the impact of surfactants on removal rates, selectivity and surface characteristics were next investigated in polishing trials at various pH levels. Depth of scratches on polished wafers and corresponding surface roughness, as well as morphology of ceria abrasive particles were characterized. Action mechanisms of selected ionic surfactants in ceria slurries have been revealed by solid-liquid interface adsorption characterization, thermogravimetric analysis and zeta potential tests. Through research finding the addition of piperazine and 2-methylpiperazine surfactant can reduce the number and depth of scratches on the surfaces of SiO2 and Si3N4 after polishing, and it exhibits better dispersibility in alkaline environment compared to acidic environment.
{"title":"Effect of ionic surfactants on shallow trench isolation for chemical mechanical polishing using ceria-based slurries","authors":"Lifei Zhang, Lile Xie, Xinchun Lu","doi":"10.1080/23311916.2023.2272354","DOIUrl":"https://doi.org/10.1080/23311916.2023.2272354","url":null,"abstract":"As the development of technology nodes proceeds to 7 nm node, chemical mechanical polishing (CMP) slurries for shallow trench isolation (STI) cannot fully meet the technical requirements. Higher goals are put forward for the polished surface qualities and the removal selectivity control. The polishing liquid exhibits issues such as easy agglomeration, removal rate of Si3N4 exceeding 50 Å/min, removal selectivity ratio of SiO2/Si3N4 below 20, increased surface scratches and roughness of SiO2 and Si3N4 after polishing exceeding 1 nm. Here, attention is given to studying the STI CMP process by introducing various ionic surfactants in ceria slurries, aiming to control removal rates, selectivity, as well as surface qualities. The findings of ball milling and settling tests were used as a starting point for choosing the effective surfactants, searching the minimal delamination phenomenon. Then the impact of surfactants on removal rates, selectivity and surface characteristics were next investigated in polishing trials at various pH levels. Depth of scratches on polished wafers and corresponding surface roughness, as well as morphology of ceria abrasive particles were characterized. Action mechanisms of selected ionic surfactants in ceria slurries have been revealed by solid-liquid interface adsorption characterization, thermogravimetric analysis and zeta potential tests. Through research finding the addition of piperazine and 2-methylpiperazine surfactant can reduce the number and depth of scratches on the surfaces of SiO2 and Si3N4 after polishing, and it exhibits better dispersibility in alkaline environment compared to acidic environment.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136068666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-26DOI: 10.1080/23311916.2023.2269655
Yetay Berhanu, Dietrich Schroeder, Bikila Teklu, Esayas Alemayehu
Safety on road networks is the utmost important factor to consider for public well-being and transportation efficiency. This study introduces a new approach that combines Getis-Ord spatial statistics and crash rate analysis to identify significant road traffic accidents (RTAs) characterized by hotspots on road segments in Addis Ababa’s road network. The study’s results visually portray the crash locations, associating them with the underlying road network, which demonstrates a notable concentration of accident hotspots, between the years from 2014 to 2019 on Addis Ababa’s roads network. The RTAs spatial analysis resulted in the identification of hotspots on 33 road segments, 3 intersections, and 10 roundabouts/squares. Among the identified hotspots, the road segment recognized as Djibouti Street, extending from Bole Edna Mall to the 22 “mazoriya” roundabouts, stands out as the most significant accident hotspot. It exhibits an average of 37.5 crashes per kilometer per year, encompassing a road segment length of 1141 m. Using both methods in this study is crucial for validating findings by identifying high-crash segments and enhancing their reliability and hotspot accuracy. This unique validation method links each traffic accident’s spatial data with the road network using both crash rate and spatial statistical analysis, effectively pinpointing accident hotspots. Given the limited resources, this approach enhances awareness of accident-prone locations, enabling the prioritization of safety measures to improve road safety. It effectively addresses spatial analysis gaps related to RTAs in Ethiopia and holds practical significance by identifying and prioritizing safety measures aimed at reducing accidents within Addis Ababa’s road network.
{"title":"Spatial analysis of road traffic accidents: Identifying hotspots for improved road safety in Addis Ababa, Ethiopia","authors":"Yetay Berhanu, Dietrich Schroeder, Bikila Teklu, Esayas Alemayehu","doi":"10.1080/23311916.2023.2269655","DOIUrl":"https://doi.org/10.1080/23311916.2023.2269655","url":null,"abstract":"Safety on road networks is the utmost important factor to consider for public well-being and transportation efficiency. This study introduces a new approach that combines Getis-Ord spatial statistics and crash rate analysis to identify significant road traffic accidents (RTAs) characterized by hotspots on road segments in Addis Ababa’s road network. The study’s results visually portray the crash locations, associating them with the underlying road network, which demonstrates a notable concentration of accident hotspots, between the years from 2014 to 2019 on Addis Ababa’s roads network. The RTAs spatial analysis resulted in the identification of hotspots on 33 road segments, 3 intersections, and 10 roundabouts/squares. Among the identified hotspots, the road segment recognized as Djibouti Street, extending from Bole Edna Mall to the 22 “mazoriya” roundabouts, stands out as the most significant accident hotspot. It exhibits an average of 37.5 crashes per kilometer per year, encompassing a road segment length of 1141 m. Using both methods in this study is crucial for validating findings by identifying high-crash segments and enhancing their reliability and hotspot accuracy. This unique validation method links each traffic accident’s spatial data with the road network using both crash rate and spatial statistical analysis, effectively pinpointing accident hotspots. Given the limited resources, this approach enhances awareness of accident-prone locations, enabling the prioritization of safety measures to improve road safety. It effectively addresses spatial analysis gaps related to RTAs in Ethiopia and holds practical significance by identifying and prioritizing safety measures aimed at reducing accidents within Addis Ababa’s road network.","PeriodicalId":10464,"journal":{"name":"Cogent Engineering","volume":"112 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134905537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：