A Comparative Study on Asperity Peak Modeling Methods

The peak identification scheme based method (three-point definition) and the spectral moments based method (spectral moment approach) are both widely used for asperity peak modeling in tribology. To discover the differences between the two methods, a great number of rough surface profile samples with various statistical distributions are first randomly generated using FFT. Then the distribution parameters of asperity peaks are calculated for the generated samples with both methods. The obtained results are compared and verified by experiment. The variation rules of the differences between the two methods with statistical characteristics of rough surfaces are investigated. To explain for the discovered differences, the assumptions by spectral moment approach that the joint distribution of surface height, slope and curvature is normal and that the height distribution of asperities is Gaussian, are examined. The results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of [z], [z′] and [z′′], and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent, 20 for instance.

Acoustic Features of the Surgut Khanty Consonants

This paper deals with the acoustic features of the Surgut Khanty consonants. The research is based on the data gathered during fieldwork in Kogalym town (2018) and the Ugut village (2019). The audio samples are provided by three native speakers of the Tromjegan, Malyi Yugan, and Bolshoi Yugan idioms. The total size of the sample database numbers more than six thousand isolated consonant pronouncements. The data for the research was obtained using oscillographic and spectrographic methods, formant locus analysis, spectral moment analysis. The analysis was performed via Praat and Emu-SDMS software. Oscillograghy and spectrography methods reveal that voiceless fricative phonemes may be voiced in intervocalic distribution. It is common for the sonants to become devoiced in the final and preconsonantal positions. Moreover, due to devoicing, different phonemes may acquire low-obstruent and obstruent consonant features. For the fricative, lateral-fricative consonants, affricates spectral moment analysis has been carried out. The spectral moments technique gives an opportunity to represent complex noise data as a relatively small set of numbers that can be processed statistically. According to the data on spectral moments, four types of noise have been defined: high-frequency low-dispersion noise resembling /s/, medium-frequency low-dispersion noise resembling /ʃ/, /tʃ/, /cc/, low-frequency medium-dispersed noise for phonemes /ɫ/, / /, low-frequency dispersed noise for phonemes /w/, /γ/. The forman analysis is used o es ima e onsonan resonan frequen ies. As shown by he formant locus analysis, the smallest values of the second formant locus are associated with the labial and velar phonemes. Larger values are associated with the coronal phonemes. The largest ones are specific to the palatal phonemes. At the same time, the acoustic features make it possible to stably distinguish the nasal /n/ - /ɲ/, wherein the opposition of the middle and fron lingual ar i ula ions is observed only in some speakers’ re ordings for the pairs /ɫ/ - / /, /tʃ/ - /cc/.

A Comparative Study on Asperity Peak Modeling Methods

The peak identification scheme based method (three-point definition) and the spectral moments based method (spectral moment approach) are both widely used for asperity peak modeling in tribology. To discover the differences between the two methods, a great number of rough surface profile samples with various statistical distributions are first randomly generated using FFT. Then the distribution parameters of asperity peaks are calculated for the generated samples with both methods. The obtained results are compared and verified by experiment. The variation rules of the differences between the two methods with statistical characteristics of rough surfaces are investigated. To explain for the discovered differences, the assumptions by spectral moment approach that the joint distribution of surface height, slope and curvature is normal and that the height distribution of asperities is Gaussian, are examined. The results show that it is unreasonable to assume a joint normal distribution without inspecting the correlation pattern of [z], [z′] and [z′′], and that the height distribution of asperities is not exactly Gaussian before correlation length of rough surface increases to a certain extent, 20 for instance.

Complexes of Pyrimidine Thiones: Mechanochemical Synthesis and Biological Evaluation

A new series of metal complexes with 1-(2-methylphenyl)-4,4,6-trimethyl pyrimidine-2-thione (2-HL1) and 1-(4-methylphenyl)-4,4,6-trimethyl pyrimidine-2-thione (4-HL2) ligands, [M(mppt)2(H2O)n] (M(II) = Cu, Mn, Co; n = 2 and M(II) = Ni, Zn; n = 0) have been synthesized using mechanochemical protocol. The complexes have been framed as [M(mppt)2(H2O)n] due to 1:2 (metal:ligand) nature of these metal complexs. Structures have been further confirmed on the basis of elemental analysis, Magnetic susceptibility measurements, electronic, infrared, far infrared, proton NMR, Mass spectral moment and thermogravimetric analysis studies. The infrared spectral data suggested that ligand behaves as a bidentate, coordinating through – N (endocyclic) and – S (exocyclic) donor atoms. All the compounds have also been screened for antibacterial and DNA photocleavage potential. Ligands complexed with Mn and Ni metals have shown the effect of substitution on their biological potentials. It was found that substitution at 4th or para position makes the ligand and its metal complexes have better antibacterial and DNA photocleaving agents.