In this study, carbon monoxide methanation was investigated with 15 %NiO doped SAPO34 zeolite supported catalysts. The SAPO34 support was produced by hydrothermal synthesis, and nickeloxide was added to the support by impregnation and surfactant impregnation method by using different solvents (water, ethanol, acetone and 1-propanol). Various characterization techniques were used to determine the physical properties of catalysts and support (N2 physisorption, XRD, SEM, TEM, FTIR). XRD analysis showed that synthesizing the catalysts with surfactant reduced the average crystal size. The average crystal sizes of the catalysts prepared by the impregnation and surfactant assisted impregnation methods are between 11.3-7.1 nm and 8.9-7.1 nm, respectievely. N2 physisorption analysis showed that catalysts prepared by the surfactant-assisted impregnation method had higher surface areas than the catalysts prepared by the classical impregnation method. It was observed that the surface area of the catalyst increased as the boiling point of the solvent increased. Scanning electron microscopy (SEM) analysis showed that particle size of the catalysts with propanol prepared by impregnation and surfactant assisted impregnation methods are 118 nm and 86 nm, respectievely. Surfactant caused to produce smaller particles. The CO methanation studies showed that highest CO conversion values were reached with Ni/SAPO34 catalyst using 1-propanol prepared by impregnation and surfactant assisted impregnation methods which gave 19.2% and 21.1% CO conversion to methane at 375C, respectievely The low methane formation rates showed that most of the CO component was adsorbed on the surface and some of it was converted to methane.
{"title":"CO Methanation Over SAPO-34 Supported Ni Catalysts","authors":"Filiz BALIKÇI DEREKAYA, Y. Kilinç","doi":"10.35378/gujs.1125710","DOIUrl":"https://doi.org/10.35378/gujs.1125710","url":null,"abstract":"In this study, carbon monoxide methanation was investigated with 15 %NiO doped SAPO34 zeolite supported catalysts. The SAPO34 support was produced by hydrothermal synthesis, and nickeloxide was added to the support by impregnation and surfactant impregnation method by using different solvents (water, ethanol, acetone and 1-propanol). Various characterization techniques were used to determine the physical properties of catalysts and support (N2 physisorption, XRD, SEM, TEM, FTIR). XRD analysis showed that synthesizing the catalysts with surfactant reduced the average crystal size. The average crystal sizes of the catalysts prepared by the impregnation and surfactant assisted impregnation methods are between 11.3-7.1 nm and 8.9-7.1 nm, respectievely. N2 physisorption analysis showed that catalysts prepared by the surfactant-assisted impregnation method had higher surface areas than the catalysts prepared by the classical impregnation method. It was observed that the surface area of the catalyst increased as the boiling point of the solvent increased. Scanning electron microscopy (SEM) analysis showed that particle size of the catalysts with propanol prepared by impregnation and surfactant assisted impregnation methods are 118 nm and 86 nm, respectievely. Surfactant caused to produce smaller particles. The CO methanation studies showed that highest CO conversion values were reached with Ni/SAPO34 catalyst using 1-propanol prepared by impregnation and surfactant assisted impregnation methods which gave 19.2% and 21.1% CO conversion to methane at 375C, respectievely The low methane formation rates showed that most of the CO component was adsorbed on the surface and some of it was converted to methane.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42808765","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}
Metallic-intermetallic laminate (MIL) composites possess intermediary properties emerging from the different laminates used. They are anisotropic since their properties are direction dependent. The laminates used in a MIL composite have different thermal conductivities and this results in anisotropic thermal resistance. In a recent study, using the composite dimensions and the electrical conductivity of the laminates used to make the MIL composite, the electrical resistance of rectangular prism-shaped MIL composites for different directions is examined. Since thermal and electrical circuits are analogues, a similar analysis can also be done for thermal conduction quantities. In this study, using the composite dimensions and the thermal conductivity of the laminates used to make the MIL composite, the thermal resistance of rectangular prism-shaped MIL composites for different directions is calculated and its direction-dependent parametric examination are made.
{"title":"Parametric Examination Anisotropic Thermal Resistance of MIL Composites","authors":"Kübra Solak, R. Mutlu","doi":"10.35378/gujs.1122095","DOIUrl":"https://doi.org/10.35378/gujs.1122095","url":null,"abstract":"Metallic-intermetallic laminate (MIL) composites possess intermediary properties emerging from the different laminates used. They are anisotropic since their properties are direction dependent. The laminates used in a MIL composite have different thermal conductivities and this results in anisotropic thermal resistance. In a recent study, using the composite dimensions and the electrical conductivity of the laminates used to make the MIL composite, the electrical resistance of rectangular prism-shaped MIL composites for different directions is examined. Since thermal and electrical circuits are analogues, a similar analysis can also be done for thermal conduction quantities. In this study, using the composite dimensions and the thermal conductivity of the laminates used to make the MIL composite, the thermal resistance of rectangular prism-shaped MIL composites for different directions is calculated and its direction-dependent parametric examination are made.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48680787","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}
Olga Nehir Öztel, H. Yilmaz, I. A. Işoğlu, A. Allahverdiyev
It is increasingly becoming important to develop three-dimensional (3-D) cell culture systems due to their numerous advantages over traditional monolayer culture. The aim of this study is to investigate the interaction of adipose derived stem cells (ADSCs) with scaffolds composed of ε-polycaprolactone (ε-PCL) and egg white. In our study; ε-PCL and egg white scaffolds were fabricated from their monomers under the catalysis of tin octoate and by polymerization by heat respectively. Characterization of PCL was carried out with Gel permeability chromatography (GPC), Fourier Transform Infrared Spectrophotometry (FTIR), Proton Nuclear Magnetic Resonance (H-NMR), Differential Scan Calorimetry (DSC) and Scanning Electron Microscopy (SEM). CM-DiI labeled ADSCs were cultured for 12 days on egg white and ε-PCL scaffolds. Cell viability was performed using MTT and nitric oxide level was evaluated for toxicity. Results showed that the number of ADSCs on egg white scaffold increased periodically throughout 12 days compared with the other groups. Although the number of ADSCs on ε-PCL scaffold increased until the 6th day of the culture, the cell number began to decrease after day 6.. These results were associated with the decomposition of PCL scaffolds that occurs through catabolic reactions. This causes the release of lactic acid which makes toxic effect on the cells. Thus, these results showed that egg white scaffold increases and protects cell adhesion and cell viability more than ε-Polycaprolactone scaffold, thus it can be used as a scaffold in tissue engineering studies that involve stem cells.
{"title":"COMPARİSON OF EGG WHİTE AND Ε-POLYCAPROLACTONE FOR THREE-DİMENSİONAL CELL CULTURE","authors":"Olga Nehir Öztel, H. Yilmaz, I. A. Işoğlu, A. Allahverdiyev","doi":"10.35378/gujs.1037746","DOIUrl":"https://doi.org/10.35378/gujs.1037746","url":null,"abstract":"It is increasingly becoming important to develop three-dimensional (3-D) cell culture systems due to their numerous advantages over traditional monolayer culture. The aim of this study is to investigate the interaction of adipose derived stem cells (ADSCs) with scaffolds composed of ε-polycaprolactone (ε-PCL) and egg white. In our study; ε-PCL and egg white scaffolds were fabricated from their monomers under the catalysis of tin octoate and by polymerization by heat respectively. Characterization of PCL was carried out with Gel permeability chromatography (GPC), Fourier Transform Infrared Spectrophotometry (FTIR), Proton Nuclear Magnetic Resonance (H-NMR), Differential Scan Calorimetry (DSC) and Scanning Electron Microscopy (SEM). CM-DiI labeled ADSCs were cultured for 12 days on egg white and ε-PCL scaffolds. Cell viability was performed using MTT and nitric oxide level was evaluated for toxicity. Results showed that the number of ADSCs on egg white scaffold increased periodically throughout 12 days compared with the other groups. Although the number of ADSCs on ε-PCL scaffold increased until the 6th day of the culture, the cell number began to decrease after day 6.. These results were associated with the decomposition of PCL scaffolds that occurs through catabolic reactions. This causes the release of lactic acid which makes toxic effect on the cells. Thus, these results showed that egg white scaffold increases and protects cell adhesion and cell viability more than ε-Polycaprolactone scaffold, thus it can be used as a scaffold in tissue engineering studies that involve stem cells.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41286769","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}
E. Ayyıldız, Gökhan Özçelik, Cevriye Gencer, E. Demirci
This paper defines a capacitated multiple-source multiple-sink shortest path problem and introduces its extension, called the capacitated multiple-source multiple-sink shortest path network interdiction problem (CMSSNIP). CMSSNIP examines the actions of attackers who attempt to maximize the total shortest path of network users trying to reach the crime locations for the aid process after causing an incident in certain regions to provide strategic information for the defense systems of the government. In this context, the exact mathematical model ensuring useful information about safe routes to network users is proposed. In this manner, to the best knowledge of authors, the CMSSNIP consisting of multiple-source nodes and multiple-sink nodes and considering capacity-demand relations between security units and crime locations is studied for the first time. Accordingly, a set of scenarios is considered based on the interdiction budget levels and the number of crime locations through a real case application to show the applicability of the model. Furthermore, computational experiments are performed to evaluate the model performance on different-sized networks. It is realized that especially the model provides resilient strategies versus interdictions in terms of obtaining the safe shortest paths at the operational level within seconds in the real case application.
{"title":"Providing homeland security strategies against interdictions in the city transportation network: A case study in Turkey","authors":"E. Ayyıldız, Gökhan Özçelik, Cevriye Gencer, E. Demirci","doi":"10.35378/gujs.1103774","DOIUrl":"https://doi.org/10.35378/gujs.1103774","url":null,"abstract":"This paper defines a capacitated multiple-source multiple-sink shortest path problem and introduces its extension, called the capacitated multiple-source multiple-sink shortest path network interdiction problem (CMSSNIP). CMSSNIP examines the actions of attackers who attempt to maximize the total shortest path of network users trying to reach the crime locations for the aid process after causing an incident in certain regions to provide strategic information for the defense systems of the government. In this context, the exact mathematical model ensuring useful information about safe routes to network users is proposed. In this manner, to the best knowledge of authors, the CMSSNIP consisting of multiple-source nodes and multiple-sink nodes and considering capacity-demand relations between security units and crime locations is studied for the first time. Accordingly, a set of scenarios is considered based on the interdiction budget levels and the number of crime locations through a real case application to show the applicability of the model. Furthermore, computational experiments are performed to evaluate the model performance on different-sized networks. It is realized that especially the model provides resilient strategies versus interdictions in terms of obtaining the safe shortest paths at the operational level within seconds in the real case application.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45618343","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}
Electronic components must be tested to allow for safe and reliable missions in radiation environments. The METU Defocusing Beamline (METU-DBL) was installed in the R&D room at the Particle Accelerator Facility (PAF) of Turkey Energy, Nuclear and Mining Research Institute (TENMRI) to perform proton irradiation tests for these electronic components in accordance with the ESA (European Space Agency) ESCC (European Space Components Coordination) No:25100 standard. METU-DBL uses beam elements such as quadrupole magnets and collimators to enlarge the beam and decrease the flux respectively for the specifications of the standard. A pretest setup was constructed and this system was operated for a total of 17 hours for three months before the METU-DBL final design was assembled. The first protective collimator is made of stainless steel 316L and was used during the period of pretests. As a result of these irradiations, the emerged radioisotopes in the collimator were observed and measured insitu with a NaI detector. These measurements were compared with the FLUKA simulations 120 days after the last irradiation. Among fourteen radioisotopes, only six of them with activity above 1.0×101 Bq/cm3 were matched.
{"title":"Radioactivation Measurement of a Protective Collimator and Comparisons with Simulation After METU-Defocusing Beamline Pretest Irradiation","authors":"B. Demirköz, P. Uslu Kiçeci, S. Uzun Duran","doi":"10.35378/gujs.1018518","DOIUrl":"https://doi.org/10.35378/gujs.1018518","url":null,"abstract":"Electronic components must be tested to allow for safe and reliable missions in radiation environments. The METU Defocusing Beamline (METU-DBL) was installed in the R&D room at the Particle Accelerator Facility (PAF) of Turkey Energy, Nuclear and Mining Research Institute (TENMRI) to perform proton irradiation tests for these electronic components in accordance with the ESA (European Space Agency) ESCC (European Space Components Coordination) No:25100 standard. METU-DBL uses beam elements such as quadrupole magnets and collimators to enlarge the beam and decrease the flux respectively for the specifications of the standard. A pretest setup was constructed and this system was operated for a total of 17 hours for three months before the METU-DBL final design was assembled. The first protective collimator is made of stainless steel 316L and was used during the period of pretests. As a result of these irradiations, the emerged radioisotopes in the collimator were observed and measured insitu with a NaI detector. These measurements were compared with the FLUKA simulations 120 days after the last irradiation. Among fourteen radioisotopes, only six of them with activity above 1.0×101 Bq/cm3 were matched.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49092827","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}
In this study, hypothesis test is investigated based on Bootstrap sample selection methods to compare more than two population means under Ranked Set Sampling. Bootstrap sample selection methods are obtained by adapting Hui’s sample selection methods for confidence interval. We also compare these adapted methods with their alternatives using simulation study. Simulation study shows that adapted methods which proposed in this paper perform quite well.
{"title":"BOOTSTRAP APPROACH FOR TESTING MORE THAN TWO POPULATION MEANS WITH RANKED SET SAMPLING","authors":"Nurdan YENİAY KOÇER, Y. Özdemir, F. Gökpınar","doi":"10.35378/gujs.1038212","DOIUrl":"https://doi.org/10.35378/gujs.1038212","url":null,"abstract":"In this study, hypothesis test is investigated based on Bootstrap sample selection methods to compare more than two population means under Ranked Set Sampling. Bootstrap sample selection methods are obtained by adapting Hui’s sample selection methods for confidence interval. We also compare these adapted methods with their alternatives using simulation study. Simulation study shows that adapted methods which proposed in this paper perform quite well.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":"8 3","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41248517","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}
Lignosus rhinocerotis (Cooke) Ryvarden, known as tiger milk mushroom, is a rare and valuable medicinal mushroom that is widely used throughout Southeast Asia and South China for treating several ailments. This study was conducted to screen the phytochemicals present in L. rhinocerotis (Cooke) Ryvarden sclerotium grown from two different environments, open field and indoor, and evaluate the antibacterial activity. In this study, phytochemical screening of ethyl acetate and methanolic extract of L. rhinocerotis (Cooke) Ryvarden sclerotium were done using various chemical tests to identify the compounds present in the extracts. All the extracts were then tested for antibacterial activity against three different bacteria including Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa at the concentrations of 20 and 30 mg/mL using disc diffusion method. Based on the phytochemical screening result, extracts of L. rhinocerotis (Cooke) Ryvarden demonstrated the presence of steroids, terpenoids, alkaloids, and flavonoids. The antibacterial assays revealed that the ethyl acetate extracts from open field and indoor cultivations exhibited moderate activities against S. aureus at 30 mg/mL with the values of the inhibition zone being 13.3 ± 0.67 mm and 11.0 ± 0.58 mm, respectively.
{"title":"Phytochemical Screening and Antibacterial Activity of Lignosus rhinocerotis (Cooke) Ryvarden Grown in Open Field and Indoor","authors":"Nurkhalida Kamal, Hazniza Adnan, J. Latip","doi":"10.35378/gujs.995742","DOIUrl":"https://doi.org/10.35378/gujs.995742","url":null,"abstract":"Lignosus rhinocerotis (Cooke) Ryvarden, known as tiger milk mushroom, is a rare and valuable medicinal mushroom that is widely used throughout Southeast Asia and South China for treating several ailments. This study was conducted to screen the phytochemicals present in L. rhinocerotis (Cooke) Ryvarden sclerotium grown from two different environments, open field and indoor, and evaluate the antibacterial activity. In this study, phytochemical screening of ethyl acetate and methanolic extract of L. rhinocerotis (Cooke) Ryvarden sclerotium were done using various chemical tests to identify the compounds present in the extracts. All the extracts were then tested for antibacterial activity against three different bacteria including Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa at the concentrations of 20 and 30 mg/mL using disc diffusion method. Based on the phytochemical screening result, extracts of L. rhinocerotis (Cooke) Ryvarden demonstrated the presence of steroids, terpenoids, alkaloids, and flavonoids. The antibacterial assays revealed that the ethyl acetate extracts from open field and indoor cultivations exhibited moderate activities against S. aureus at 30 mg/mL with the values of the inhibition zone being 13.3 ± 0.67 mm and 11.0 ± 0.58 mm, respectively.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41519939","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}
Abstract In this study, some electronic, hydrophobic and thermochemical parameters of 28 different 5,8-quinolinequinone derivatives having diverse substituents have been calculated by using DFT (B3LYP)/6-31G(d, p) method and basis set. Relationships between different molecular descriptors have been studied by using molecular polarizability (α), dipole moment (μ), EHOMO, ELUMO, molecular volume (Vm), ionization potential (IP), electron affinity (EA), electronegativity (χ), molecular hardness (η), molecular softness (S), electrophilic index (ω), molar refractivity (MR), octanol–water partition coefficient (log P), thermochemical properties (entropy (Se), capacity of heat (C)); as to investigate activity relationships with molecular structure. In addition, the QSAR/QSPR between molecular properties and biological activity (anti-proliferative and anti-inflammatory activity) has been investigated, where R, R2, F, P and RMSE have taken into account in order to find a statistically correct model in QSAR studies. The dependence of the electronegativity parameter on both electronic and thermochemical parameters is found to be the most correlated parameter.
{"title":"The study on QSAR and relations between molecular descriptors of 5, 8-quinoline quinones derivatives","authors":"Y. Gülseven Sıdır, İ. Sıdır","doi":"10.35378/gujs.1051216","DOIUrl":"https://doi.org/10.35378/gujs.1051216","url":null,"abstract":"Abstract \u0000In this study, some electronic, hydrophobic and thermochemical parameters of 28 different 5,8-quinolinequinone derivatives having diverse substituents have been calculated by using DFT (B3LYP)/6-31G(d, p) method and basis set. Relationships between different molecular descriptors have been studied by using molecular polarizability (α), dipole moment (μ), EHOMO, ELUMO, molecular volume (Vm), ionization potential (IP), electron affinity (EA), electronegativity (χ), molecular hardness (η), molecular softness (S), electrophilic index (ω), molar refractivity (MR), octanol–water partition coefficient (log P), thermochemical properties (entropy (Se), capacity of heat (C)); as to investigate activity relationships with molecular structure. In addition, the QSAR/QSPR between molecular properties and biological activity (anti-proliferative and anti-inflammatory activity) has been investigated, where R, R2, F, P and RMSE have taken into account in order to find a statistically correct model in QSAR studies. The dependence of the electronegativity parameter on both electronic and thermochemical parameters is found to be the most correlated parameter.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46126693","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}
Spoofed speech detection is recently gaining attention of the researchers as speaker verification is shown to be vulnerable to spoofing attacks such as voice conversion, speech synthesis, replay, and impersonation. Although various different methods have been proposed to detect spoofed speech, their performances decrease dramatically under the mismatched conditions due to the additive or reverberant noises. Conventional speech enhancement methods fail to recover the performance gap, hence more advanced techniques seem to be necessary to solve the noisy spoofed speech detection problem. In this work, Denoising Autoencoder (DAE) is used to obtain clean estimates of i-vectors from their noisy versions. ASVspoof 2015 database is used in the experiments with five different noise types, added to the original utterances at 0, 10, and 20 dB signal-to-noise ratios (SNR). The experimental results verified that the DAE provides a more robust spoof detection, where the conventional methods fail.
{"title":"Robust Spoofed Speech Detection with Denoised I-vectors","authors":"Gökay Dişken","doi":"10.35378/gujs.1062788","DOIUrl":"https://doi.org/10.35378/gujs.1062788","url":null,"abstract":"Spoofed speech detection is recently gaining attention of the researchers as speaker verification is shown to be vulnerable to spoofing attacks such as voice conversion, speech synthesis, replay, and impersonation. Although various different methods have been proposed to detect spoofed speech, their performances decrease dramatically under the mismatched conditions due to the additive or reverberant noises. Conventional speech enhancement methods fail to recover the performance gap, hence more advanced techniques seem to be necessary to solve the noisy spoofed speech detection problem. In this work, Denoising Autoencoder (DAE) is used to obtain clean estimates of i-vectors from their noisy versions. ASVspoof 2015 database is used in the experiments with five different noise types, added to the original utterances at 0, 10, and 20 dB signal-to-noise ratios (SNR). The experimental results verified that the DAE provides a more robust spoof detection, where the conventional methods fail.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45933787","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}
In this study, unlike the porous carbon as a conventional catalyst support material in fuel cells, nonporous carbon was synthesized in the presence of different acid concentrations (0.2 M-1 M) and investigated as a support material for platinum (Pt) catalysts in the oxygen reduction reaction (ORR). Since the micropore volume of the synthesized carbons is negligible, the detected surface areas with Brunauer-Emmett-Teller (BET) method were in the range of 19-23 m2/g. Among the support materials, the carbon-supported Pt catalyst synthesized in the presence of 1 M acid was investigated electrochemically in terms of hydrogen oxidation (HOR) and ORR half-cell reactions in the three-electrode system. The Pt catalyst supported with nonporous carbon, synthesized using 1 M acid, reached the maximum limiting current value of -0.25 mA/cm2 (@2500 rpm) at ORR hydrodynamic curves. Low internal and charge transfer resistances of the same catalyst in electrochemical impedance spectroscopy (EIS) analysis are attributable to its nonporous structure.
{"title":"Alternative Support Material to Platinum Catalyst Used for Oxygen Reduction Reaction: Nonporous Carbon","authors":"Ayşenur Öztürk, Ayşe Bayrakçeken","doi":"10.35378/gujs.1054803","DOIUrl":"https://doi.org/10.35378/gujs.1054803","url":null,"abstract":"In this study, unlike the porous carbon as a conventional catalyst support material in fuel cells, nonporous carbon was synthesized in the presence of different acid concentrations (0.2 M-1 M) and investigated as a support material for platinum (Pt) catalysts in the oxygen reduction reaction (ORR). Since the micropore volume of the synthesized carbons is negligible, the detected surface areas with Brunauer-Emmett-Teller (BET) method were in the range of 19-23 m2/g. Among the support materials, the carbon-supported Pt catalyst synthesized in the presence of 1 M acid was investigated electrochemically in terms of hydrogen oxidation (HOR) and ORR half-cell reactions in the three-electrode system. The Pt catalyst supported with nonporous carbon, synthesized using 1 M acid, reached the maximum limiting current value of -0.25 mA/cm2 (@2500 rpm) at ORR hydrodynamic curves. Low internal and charge transfer resistances of the same catalyst in electrochemical impedance spectroscopy (EIS) analysis are attributable to its nonporous structure.","PeriodicalId":12615,"journal":{"name":"gazi university journal of science","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48672090","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：