Implementation of Supervised PCA for Global Sensitivity Analysis of Models with Correlated Inputs

Global Sensitivity Analysis (GSA) plays a significant role in quantifying the tangible impact of model inputs on the uncertainty of response variable. As GSA results are strongly affected by correlated inputs, several studies considered this issue, but most of them are quite time-consuming, labor-intensive, and difficult to implement. Accordingly, this paper puts forward a novel strategy based on the Supervised Principal Component analysis (Supervised PCA), benefiting from the Reproducing Kernel Hilbert Space (RKHS). Indeed, by conducting one kind of variance-based sensitivity analysis (SA), a renowned method exclusively customized for models with orthogonal inputs, on Supervised PCA (SPCA) regression, the impact of correlation structure of input variables is effectively taken into account. The ability of the suggested technique is evaluated with five test cases as well as two hydrologic and hydraulic models, and the results are compared and contrasted with those obtained from the correlation ratio method taken as a robust benchmark solution. It is found that the proposed method satisfactorily identifies the sensitivity ordering of model inputs. Furthermore, it is proved in this study that the performance of the proposed approach is also supported by the total contribution index in the derived covariance decomposition equation. Moreover, the proposed method compared to the correlation ratio method, is found to be time efficient and easy to implement. Overall, the proposed scheme is appropriate for high dimensional, relatively nonlinear or expensive models with correlated inputs whose coefficient of determination is larger than 0.5.

Principles of certification of metals for susceptibility to brittleness by the criterion of critical strength

Problem definition. Existing evaluation system of liability to brittle fracture is based on specifying the critical temperature Tc of ductile/brittle transition for specimens with stress concentrator (SC) and uses relative values of impact toughness (KCV, KCU) and widening (ψк). Thus the Tc becomes relative and it is not possible to measure brittleness or embrittlement degree for specimens with SC. Paper purpose. Neutralize the system faults of evaluation system of liability to brittle fracture of constructional alloys with SC. The concept is to change the KCV (KCU) or ψк parameters by critical strength parameter (ϭ0,2с at Tc). Conclusions. Fracture of the specimen with SC (ϭNF) on YTS (ϭ0,2с) at Tc (or room TR) as embrittlement criterion is proposed instead of relative values of (KCV, KCU) and (ψк). The ϭNF / ϭ0,2 = BrNF ratio is a degree of reliability for specimen with SC (BrNF > 1) or embrittlement measure (BrNF < 1). The BrNF value is a quantitative measure of the fracture resistivity of the specimen with SC or crack. Correlation ratio between Br and BrNF for each type of SC has been found. It allows to use the calculation of embrittlement liability based on metal strength for test of metals without full scale tests of metal specimens with SC. Keywords: embrittlement; fracture degree; fracture resistivity; critical temperature; critical strength; strengthreliability of the specimen with SC

Development of new calculation method for zenith troposphere delay of GPS signals

Beginning from 1980s, the steady increase of total amount of deposited water or general amount of water vapor in the atmosphere almost above all regions of the Earth is observed. The changing of this parameter over the oceans strongly correlates with the temperature of sea water surface both in time and space. Obviously, the increase of total amount of deposited water or sum amount of water vapor leads to the growth of corresponding components of troposphere delay of GPS signals called “wet delay”. To achieve the goal set, foremost, the correlation properties of “wet delay” of GPS signals associated with the regularities of changing of total amount of deposited water in the atmosphere have been studied. Carried out analysis of actual materials of correlation properties of “wet” troposphere delay justified the presence of the aspects negatively affecting the correlation ratio of total amount of deposited water. Special correlation indexes allowing to regulate the balance of separate components of correlation function of “wet delay” are offered and their extreme nature shown as well. A new calculation technique for zenith wet delay by set value of integrated parameters of water vapor in the atmosphere has been developed.

ACTIVITY AND CONTENT OF ISOZYMES OF ASPARTATE AMINOTRANSFERASE IN CONNECTION WITH THE SURVIVAL OF BULL SPERMATOZOA

The activity and content of aspartate aminotransferase (AST) isoforms in bovine ejaculates due to sperm survival were studied. Ejaculates of bulls of the Ukrainian black-spotted dairy breed (n = 22) were selected for research. In freshly obtained and incubated semen the activity and isozymes of AST was studied in connection with spermatozoa survival at a temperature of 2-4 ° C (on the first, second, third and fourth days) until the cessation of rectilinear translational movement. AST activity depended on the duration of sperm survival. When survival was more than 100 hours - AST activity was the highest - 65.2 ± 1.7 nmol / min × mg of protein. When survival was lower - up to 100 hours, enzymatic activity lower by 26.8% (P <0.001). Two enzymes of the enzyme (AST1 and AST2) were found in the semen of the fetuses, which differ in electrophoretic mobility and intensity of staining in 7.5% polyacrylamide gel. The established correlation with sperm survival time has a strong straight line for AST1 (η2АSТ1 = 0.88) and inverse - for AST2 (η2АSТ2 = 0.87) isozymes. During sperm incubation, the ratio of AST isozymes changes - the content of AST1 increases and decreases - AST2. The correlation ratio for sperm survival for enzyme activity and isozymes is up to 100 hours, respectively. - η2АSТ = 0.83; η2АSТ1 = 0.68 and η2АSТ2= 0.69 and more than 100 hours - η2АSТ = 0.75; η2АSТ1= 0.92 and η2АSТ2= 0.69. Therefore, ejaculates of bulls with reduced sperm survival are characterized by lower AST activity and, accordingly, the speed of the amino acid transamination process. Increased supply of substrates from the cytosol in the mitochondria of germ cells ensures high survival of sperm. Changes in the activity and content of AST isozymes, which characterize the energy supply of germ cells, can serve as a criterion for the physiological quality of sperm of freshly obtained sperm.

Analysis of Vibration Field Parameters of the City by the Correlation-Regression Method

Analysis of the parameters of the vibration field of the city was carried out on the example of the area of Syktyvkar. The vibroseismic monitoring data were used as a source material. We obtained the estimates of the mathematical expectation, variances and standard deviations, checked the normal distribution of random variables. The values of the correlation coefficient and correlation ratio were determined applying the method of correlation-regression analysis and carrying out the necessary calculations. Distribution diagrams were also constructed and approximating functions and estimated equations were obtained. This approach can be used to predict the parameters of the vibration field on the city territory and made it possible to give recommendations on its application as selection rationale of construction sites and environmental survey in the field of man-induced impact.

Элистинский курганный могильник: анализ соотношения курганов и погребений раннего и среднего бронзового века

Introduction. Elista grave field is a largest and most investigated one in the Ergeni Uplands, with the bulk of barrows and burials dated to the Bronze Age. Burial mound sites in the mentioned area are distinguished by linear positioning of tumuli — the most sizeable groups constitute chains of kurgans located transversally along watershed lines. Plateau-like ridges may comprise groups consisting of several parallel kurgan chains. Goals. The study aims at analyzing the correlation (ratio) between kurgans and burials of Early and Middle Bronze Age cultures within the grave field of Elista. Results. The work reveals some specific functions of under-kurgan rooms (space) in different cultures of the examined period. So, burial mounds of the Yamnaya culture contained one central burial each. In the Early Catacomb era, inlet burials were made only in ‘own’ barrows, while the arrived North Caucasian steppe culture gave rise to scattered cases of constructing inlet burials in culturally alien kurgans. Pit-catacomb burials were characterized by somewhat differing use of foreign culture barrows: one such construct virtually demolished the main burial in a Yamnaya kurgan; in another instance, the creation of an inlet burial was followed by heaping quite a plenty of soil which resulted in that the tumulus became several times as large. The distinctive feature is that all the monuments are arranged along the watershed without visible clustering. The largest group is that of kurgans and burials referred to as the East Manych Catacomb culture. Catacomb barrows were inserted into the existing chain, and dimensionally the bulk of them were virtually identical to previous monuments. Conclusions. The analysis shows research of Early and Middle Bronze Age burials should focus not only on quantitative properties in separate kurgans. When it comes to counting inlet burials it is critical to identify the cultural and chronological affiliation of the main burial. Moreover, it is important to obtain additional data, such whether the burial is located inside the tumulus or below the latter, whether there is any trace of later soil heaping, etc. This may be instrumental in discovering additional groups of inlet burials that vary from ‘common’ to ‘elite’ ones and could have been accompanied by several-fold enlargement of the initial (original) tumulus.

Transition from Electromechanical Dynamics to Quasi-Electromechanical Dynamics Caused by Participation of Full Converter-Based Wind Power Generation

Previous studies generally consider that the full converter-based wind power generation (FCWG) is a “decoupled” power source from the grid, which hardly participates in electromechanical oscillations. However, it was found recently that strong interaction could be induced which might incur severe resonance incidents in the electromechanical dynamic timescale. In this paper, the participation of FCWG in electromechanical dynamics is extensively investigated, and particularly, an unusual transition of the electromechanical oscillation mode (EOM) is uncovered for the first time. The detailed mathematical models of the open-loop and closed-loop power systems are firstly established, and modal analysis is employed to quantify the FCWG participation in electromechanical dynamics, with two new mode identification criteria, i.e., FCWG dynamics correlation ratio (FDCR) and quasi-electromechanical loop correlation ratio (QELCR). On this basis, the impact of different wind penetration levels and controller parameter settings on the participation of FCWG is investigated. It is revealed that if an FCWG oscillation mode (FOM) has a similar oscillation frequency to the system EOMs, there is a high possibility to induce strong interactions between FCWG dynamics and system electromechanical dynamics of the external power systems. In this circumstance, an interesting phenomenon may occur that an EOM may be dominated by FCWG dynamics, and hence is transformed into a quasi-EOM, which actively involves the participation of FCWG quasi-electromechanical state variables.

Transition from Electromechanical Dynamics to Quasi-Electromechanical Dynamics Caused by Participation of Full Converter-based Wind Power Generation

Previous studies generally reckon that the full converter-base wind power generation (FCWG) is a ’decoupled’ power source from the grid, which hardly participates in electromechanical oscillations. However, it is found recently that strong interaction could be induced which might incur severe resonance incidents in electromechanical dynamic timescale. In this paper, the participation of FCWG in electromechanical dynamics is extensively investigated, and particularly, an unusual transition of electromechanical oscillation mode (EOM) is uncovered for the first time. The detailed mathematical models of open-loop and closed-loop power systems are firstly established, and modal analysis is employed to quantify the FCWG participation in electromechanical dynamics, with two new mode identification criteria, i.e., FCWG dynamics correlation ratio (FDCR) and quasi-electromechanical loop correlation ratio (QELCR). On this basis, the impact of different wind penetration levels and controller parameter settings on the participation of FCWG is investigated. It is revealed that if an FOM has a similar oscillation frequency to the system EOMs, there is a high possibility to induce strong interactions between FCWG dynamics and system electromechanical dynamics of the external power systems. In this circumstance, an interesting phenomenon may occur that an EOM may be dominated by FCWG dynamics, and hence is transformed into a quasi-EOM, which actively involves the participation of FCWG quasi-electromechanical state variables.