Approximate Estimation Research Articles

Theory of Anhysteretic Remanent Magnetization of Single-Domain Grains

Abstract—A new approach to the solution of kinetic equations describing the process of formation of anhysteretic remanent magnetization (ARM) is proposed, which made it possible to accelerate the numerical calculation of the process of formation of ARM by two orders of magnitude for uniaxial oriented non-interacting single-domain particles, while practically not yielding in accuracy to a strict numerical solution. It follows from the calculation results that the susceptibility of ARM is entirely determined by the magnitude of the particle’s coercivity parameter. The data of the previous approximate calculations of ARM value are compared with the exact results presented here and it is shown that the discrepancy between the exact data and the approximate estimates increases with the growth of g, but remains relatively small, within 23%. The proposed algorithm for the rapid calculation of kinetic equations allows us to analyze with physical rigor the method of pseudo-Thellier estimation of paleointensivity for an ensemble of single-domain particles, which is supposed to be done in subsequent works.

Reduced Order DFIG Models for PLL-Based Grid Synchronization Stability Assessment

This paper presents a reduced-order modeling approach to study the grid synchronization stability of type-3 wind turbine generator (WTG) by considering the dynamics of the phase-locked loop (PLL) alone. The proposed model is validated by comparing its time-domain response and small-signal results with the full-order dynamical model of a type-3 WTG system. Extension of the proposed reduced-order model is shown in a wind farm with N numbers of the WTGs, and time-domain simulations are performed under stable and unstable scenarios. The developed model is further utilized for directly assessing the transient stability of a doubly-fed induction generator-based wind turbine generator (DFIG-WTG) system leveraging Lyapunov's direct method. From the direct transient stability assessment methodology, an approximate estimate of the critical clearing time (CCT) is obtained for the DFIG-WTG system to ensure large-signal stability following severe grid fault. Finally, the parametric conditions are derived theoretically, which can determine the stable and unstable region of operation of the DFIG-WTG system with respect to the PLL parameters, grid impedance, and input wind speed.

Maximum approximate likelihood estimation in accelerated failure time model for interval-censored data.

The approximate Bernstein polynomial model, a mixture of beta distributions, is applied to obtain maximum likelihood estimates of the regression coefficients, the baseline density and the survival functions in an accelerated failure time model based on interval censored data including current status data. The estimators of the regression coefficients and the underlying baseline density function are shown to be consistent with almost parametric rates of convergence under some conditions for uncensored and/or interval censored data. Simulation shows that the proposed method is better than its competitors. The proposed method is illustrated by fitting the Breast Cosmetic and the HIV infection time data using the accelerated failure time model.

Comprehensive analysis on subchondral bone marrow lesions of human osteoarthritis by integrating bulk and single-cell transcriptomes

ObjectiveThis study aims to demonstrate the cellular composition and underlying mechanisms in subchondral bone marrow lesions (BMLs) of knee osteoarthritis (OA).MethodsBMLs were assessed by MRI Osteoarthritis Knee Score (MOAKS)≥2. Bulk RNA-sequencing (bulk-seq) and BML-specific differentially expressed genes (DEGs) analysis were performed among subchondral bone samples (including OA-BML=3, paired OA-NBML=3; non-OA=3). The hub genes of BMLs were identified by verifying in independent datasets and multiple bioinformatic analyses. To further estimate cell-type composition of subchondral bone, we utilized two newly developed deconvolution algorithms (MuSiC, MCP-counter) in transcriptomic datasets, based on signatures from open-accessed single-cell RNA sequencing (scRNA-seq). Finally, competing endogenous RNA (ceRNA) and transcription factor (TF) networks were constructed through multiple predictive databases, and validated by public non-coding RNA profiles.ResultsA total of 86 BML-specific DEGs (up 79, down 7) were identified. IL11 and VCAN were identified as core hub genes. The “has-miR-424-5p/lncRNA PVT1” was determined as crucial network, targeting IL11 and VCAN, respectively. More importantly, two deconvolution algorithms produced approximate estimations of cell-type composition, and the cluster of heterotopic-chondrocyte was discovered abundant in BMLs, and positively correlated with the expression of hub genes.ConclusionIL11 and VCAN were identified as the core hub genes of BMLs, and their molecular networks were determined as well. We profiled the characteristics of subchondral bone at single-cell level and determined that the heterotopic-chondrocyte was abundant in BMLs and was closely linked to IL11 and VCAN. Our study may provide new insights into the microenvironment and pathological molecular mechanism of BMLs, and could lead to novel therapeutic strategies.

Model-based event-triggered control of switched discrete-time systems

In this paper, we aim to study model-based event-triggered control for a class of uncertain switched discrete-time systems composed of stabilizable and unstabilizable subsystems. A nominal model is introduced at the controller side to form a dynamic controller so that it can provide a kind of approximate estimate of the system state for system input even the overall switched discrete-time system is running in open-loop during any two consecutive event-triggered instants. By using multi-Lyapunov function method and the average dwell time switching strategy, stability conditions given in linear matrix inequality form for the closed-loop switched discrete-time system are derived. The design of control gains is also given. Finally, a numerical example and a physical example are provided to verify the effectiveness and usefulness of the proposed method.

Prediction of speech understanding with the transcutaneous partially implantable bone conduction hearing system Osia®. German Version

The active transcutaneous, partially implantable osseointegrated bone conduction system Cochlear™ Osia® (Cochlear, Sydney, Australia) has been approved for use in German-speaking countries since April 2021. The Osia is indicated for patients with conductive (CHL) or mixed hearing loss (MHL) with an average bone conduction (BC) hearing loss of 55 dB or less, or with single-sided deafness (SSD). The aim of this retrospective study was to investigate the prediction of postoperative speech recognition with Osia and to evaluate the speech recognition of patients with MHL and an aided dynamic range of less than 30 dB with Osia. Between 2017 and 2022, 29adult patients were fitted with the Osia, 10patients (11ears) with CHL and 19patients (21ears) with MHL. MHL was subdivided into two groups: MHL‑I with four-frequency pure-tone average in BC (BC-4PTA) ≥ 20 dB HL and < 40 dB HL (n = 15patients; 20ears) vs. MHL-II with BC-4PTA ≥ 40 dB HL (n = 4patients; 5ears). All patients tested abone conduction hearing device on asoftband preoperatively. Speech intelligibility in quiet was assessed preoperatively using the Freiburg monosyllabic test unaided and with the test system and postoperatively with Osia. The maximum monosyllabic score (mEV) unaided and the monosyllabic score with the test system at 65 dB SPL were correlated with the postoperative monosyllabic score with Osia at 65 dB SPL. Preoperative prediction of postoperative outcome with Osia was better using the mEV than the EV at 65 dB SPL with the test device on the softband. Postoperative EV was most predictive for patients with CHL and least predictive for patients with mixed hearing loss with 4PTA BC ≥ 40 dB HL. For the test device at softband, results tended to show the minimum achievable outcome and the mEV tended to predict the realistically achievable outcome. Osia can be used for the treatment of CHL and MHL within the indication limits. The average preoperative bone conduction hearing threshold also provides an approximate estimate of the postoperative EV with Osia, for which the most accurate prediction is obtained using the preoperative mEV. Prediction accuracy decreases from aBC-4PTA of ≥ 40 dB.

RETRACTED ARTICLE: Intelligent monitoring methodology for large-scale logistics transport vehicles based on parallel Internet of Vehicles

The essence of the Internet of Vehicles is a social and physical information system, including the psychological and organizational factors of human beings. The complexity of the Internet will lead to certain deviations when monitoring vehicles. Therefore, the Parallel Internet of Vehicles is employed to monitor the information on large-scale logistics transport vehicles. This platform is built based on the ACP intelligent approach, which consists of three parts: An artificial system (A), a computational experiment (C), and parallel execution (P). The Adaboost algorithm is used to extract information on large-scale logistics transport vehicles from the ACP parallel Internet of Vehicles, and the Tabu search strategy is applied to optimize the Monte Carlo positioning algorithm. The approximate optimal estimation is obtained by optimizing the filtering to eliminate vehicle positions with fewer possibilities. The weight of important sampling values of the independent vehicle node positions is integrated to complete the posterior probability distribution estimation of the possible positions of vehicles, in order to realize vehicle position monitoring. It is verified that the root-mean square error of the algorithm when positioning a vehicle is less than 0.18, and the monitoring deviation is quite small.

Low regularity estimates for CutFEM approximations of an elliptic problem with mixed boundary conditions

We show error estimates for a cut finite element approximation of a second order elliptic problem with mixed boundary conditions. The error estimates are of low regularity type where we consider the case when the exact solution u ∈ H s u \in H^s with s ∈ ( 1 , 3 / 2 ] s\in (1,3/2] . For Nitsche type methods this case requires special handling of the terms involving the normal flux of the exact solution at the the boundary. For Dirichlet boundary conditions the estimates are optimal, whereas in the case of mixed Dirichlet-Neumann boundary conditions they are suboptimal by a logarithmic factor.

Inference on the stress-strength reliability of multi-component systems based on progressive first failure censored samples

This paper studies the statistical estimation of the stress-strength reliability of multi-component systems under the progressive first failure censoring samples, where the lifetime distribution of each component follows the modified Kumaraswamy distribution. Both the point and interval estimations of the parameters in the reliability function are considered. To this aim, some estimations such as maximum likelihood estimation (MLE), asymptotic confidence intervals, uniformly minimum variance unbiased estimation (UMVUE), approximate Bayes estimation, and highest posterior density (HPD) intervals are obtained. By employing the Monte Carlo simulation, comparison of the performance between different estimates is provided. The paper then analyzes a case study for illustration of the proposed method.

Approximate estimation of cell-type resolution transcriptome in bulk tissue through matrix completion.

Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool for uncovering cellular heterogeneity. However, the high costs associated with this technique have rendered it impractical for studying large patient cohorts. We introduce ENIGMA (Deconvolution based on Regularized Matrix Completion), a method that addresses this limitation through accurately deconvoluting bulk tissue RNA-seq data into a readout with cell-type resolution by leveraging information from scRNA-seq data. By employing a matrix completion strategy, ENIGMA minimizes the distance between the mixture transcriptome obtained with bulk sequencing and a weighted combination of cell-type-specific expression. This allows the quantification of cell-type proportions and reconstruction of cell-type-specific transcriptomes. To validate its performance, ENIGMA was tested on both simulated and real datasets, including disease-related tissues, demonstrating its ability in uncovering novel biological insights.

Probabilistic shear wave velocity model based on downhole test database for Apennine flysch formations

Defining a reference shear wave velocity profile (Vs) is crucial for seismic-hazard assessment and seismic response analysis. However, selecting a reference velocity profile is not straightforward, mainly because of the high variability of shear wave velocity in complex formations. This study considered 26 shear wave profiles from downhole tests carried out in the Laga Basin (Gran Sasso, Central Apennines), where the soil can be categorised as complex owing to the chaotic succession of turbidite and Quaternary continental deposits. Downhole tests and stratigraphy were used to (i) develop a probabilistic model for predicting the shear wave profiles calibrated on the collected test data and (ii) propose an outlier detection method for estimating the first fundamental frequency of the deposit from horizontal-to-vertical spectral ratio (HVSR) analyses. Specifically, the stochastic shear wave model provides the uncertainty of the first fundamental frequency estimated from downhole tests based on a simplified mechanics-based formulation. The defined bounds, were forward uncertainty propagation following a Monte Carlo approach, have been used to define the criteria for outlier detection in HVSR frequency assessments, given an approximate estimate of the equivalent depth.

POST-TECTOGENIC EVENTS AND EXHUMATION PROCESSES IN SVEKOKARELIDES OF THE LADOGA REGION

Elements of the structure of the Svecokarelian pericratonic zone of the Karelian Massif (SE Fennoscandia), formed after the main events of the Svekofennian tectogenesis, have been identified and characterized. Dated age intervals of the orogenic stage and post-orogenic extensional collapse manifestation, determined the depth levels of the corresponding structures and visualized the scheme of differentiated exhumation of the deep complexes of the post-Proterozoic Savo-Ladoga movable zone. Approximate estimations of exhumation rates of deep material at certain stages of the Precambrian evolution of this zone are given.

Совершенствование методологии оценки экономической эффективности государственных закупок лекарственных средств

The study raises the issue of evaluating the effectiveness of public procurement, especially procurement of medicines. This topic is relevant, since a significant part of state funding is directed specifically to the healthcare system. In addition, the quality of organization of procurement activities affects the work of hospitals and polyclinics. In this regard, the improvement of the methodology for assessing the economic efficiency of public procurement, particularly procurement of medicines, is critically important. The paper presents the results of statistical analysis showing the need to develop a more comprehensive methodology that takes into account the volume of failed purchases in the context of efficiency assessment. The issue of "repeated" purchases was studied separately, since information about them would allow drawing conclusions about the existing patterns in tenders and the reasons for recognizing a purchase as failed. The methodological novelty is associated with the description of the approach to the formation of a sample for research and the algorithm for identifying "repeated" procurement procedures. All calculations are based on real data on procurement under the Federal Law No. 44-FZ for 2021–2022. The data was aggregated from the Unified Information System for Procurement. A statistical analysis of the scale of failed and repeated purchases in the context of regions, medicines and pharmacotherapeutic groups has been conducted. Based on the analysis, approximate estimates of hidden costs of the state budget related to re-organizing and re-conducting of trade procedures are given. The results of the work can be used for further scientific research in the field of public procurement efficiency, as well as to improve public policy in the field of procurement and provision of medicines.

A Three-Way Decision Methodology With Regret Theory via Triangular Fuzzy Numbers in Incomplete Multiscale Decision Information Systems

The three-way decision theory provides a three-way philosophical thinking to solve problems, and the regret theory quantifies the risk preferences of decision makers under different psychological behaviors. On the one hand, the combination of these two theories makes models more practical by considering the psychological behaviors of decision makers. On the other hand, we can effectively combine the advantages of the three-way decision theory with the regret theory to highlight the interpretability of decision making processes. In this paper, we propose a novel approximate estimation method for incomplete utility values via the regret theory and establish a wide sense of three-way decision model on incomplete multi-scale decision information systems. First, the degree of consistency for each scale is measured via using the dependency degree, then the optimal subsystem is selected by evaluating the scale selection cost. Further, the incomplete multi-scale evaluation information is transformed into triangular fuzzy numbers via linguistic term sets. Second, in light of fuzzy evaluation values and trade-off factors, an estimation method for incomplete fuzzy subsystems is constructed, which can be used to calculate the utility difference and regret-rejoicing values for pairwise comparisons. Finally, from the perspective of human cognition, the tri-partition and the corresponding decision rules are built by the tolerance degree, and the ranking of objects is calculated by the relative closeness degree. Additionally, multi-aspect comparative and experimental analyses are performed by extensive experiments, and the feasibility, validity and stability of the constructed model are shown by parametric analyses.

The role of non-numerical information in the perception of temporal numerosity.

Numerosity perception refers to the ability to make rapid but approximate estimates of the quantity of elements in a set (spatial numerosity) or presented sequentially (temporal numerosity). Whether numerosity is directly perceived or indirectly recomputed from non-numerical features is a highly debated issue. In the spatial domain, area and density have been suggested as the main parameters through which numerosity would be recomputed. In the temporal domain, stimuli duration and temporal frequency could be similarly exploited to retrieve numerosity. By adapting a psychophysical technique previously exploited in the spatial domain, we investigated whether temporal visual numerosity is directly perceived. Adult participants observed sequences of visual impulses sampled from a stimulus space spanning several levels of temporal frequency and duration (and hence numerosity), and then reproduced the sequence as accurately as possible via a series of keypresses. Crucially, participants were not asked to reproduce any particular property (such as number of impulses) but were free to choose any available cue (such as total duration, or temporal frequency). The results indicate that while the overall sequence duration was barely considered, numerosity and temporal frequency were both spontaneously used as the main cues to reproduce the sequences, with a slight but significant dominance of numerosity. Overall, the results are in line with previous literature suggesting that numerosity is directly encoded, even for temporal sequences, but a non-numerical feature (temporal frequency) is also used in reproducing sequences.

On the Possibilities and Constraints of Studying the Ethnic Makeup of the Population Using Census Data from the Principality and Kingdom of Serbia: the Case of Eastern Serbia

Since the first half of the nineteenth century, various census data have been collected regarding the ethnic characteristics of the Serbian population, although the data are incomplete and collected irregularly. The ten censuses conducted in the Principality of Serbia between 1833 and 1874 have immense archival value, but their usefulness for ethno-demographic studies is limited. Similarly, while the statistics collected in the censuses of the Kingdom of Serbia from 1874 to 1910 are somewhat more reliable than the previous ones, they suffer from the absence of a direct question on ethnicity.&#x0D; To determine the ethnic structure of the population during this time period, a researcher had to rely on an indirect approach through the identification of ethnic groups based on their linguistic affiliation. However, it is important to note that this method only provides an approximate estimation of ethnic composition. Despite this limitation, available census data can still provide valuable insights into the ethnic composition of the population of the Principality and Kingdom of Serbia, with the number and share of the Vlach population as the most numerous ethnic minority taking centre stage. This means that any data analyses must begin with the understanding that the indicators can only be presented for the Romanian-speaking population.&#x0D; If we accept the indirect approach to determining population ethnicity, we can deduce from the data that the number of Vlachs in Eastern Serbia increased up to 1895, and their percentage share increased up to 1884. It is noteworthy that the dynamics of the number of Vlachs until 1895 were relatively stable, implying that the increase was practically linear and consistent with the growth tendency of Serbia’s overall population at the time.&#x0D; Within the framework of demographic analysis, data on declared Vlachs in almost all censuses since the post-war census cannot be used to derive explainable demographic indicators. Therefore, it is reasonable to suspect that such data would also be of limited use in other academic fields, particularly in law, politics, and public life in general. This highlights the importance of paying closer attention to earlier ethno-statistic records, especially the first statistical aberration reported in the last decade of the nineteenth century.

Estimate of the Prevalence of Vascular Malformations

Objectives: To estimate the prevalence of vascular malformations using retrospective data collected from 1999 to 2020 in a specialty vascular anomalies service. Methods: The vascular anomalies service associated with the Royal Children’s Hospital provides a reference service to both adults and children, covering the entire state of Victoria, Australia, which has a population of 6.7 million and around 70,000 births per year. A database of patients was interrogated to identify those treated by the service over the study period with a diagnosis of vascular malformation, excluding capillary malformations. A total of 1501 patients were identified, including 1233 with slow-flow malformations and 147 with arteriovenous malformations. Prevalence was calculated as the number of cases born per year who attended the service plus those estimated as yet to attend for assessment, divided by the average number of live births each year. This was calculated for a selected period comprising the years when the numbers were expected to be most stable. Results: The prevalence of slow-flow malformations is estimated to be 1 case per thousand livebirths. Approximate estimates of cases per 100,000 births for individual lesions are: venous malformation 45, lymphatic malformation 35, intramuscular slow-flow malformation 10, complex malformations (Klippel-Trenaunay and CLOVES) 4, glomuvenous malformation 5, and verrucous venous malformation 2. The prevalence of extracranial arteriovenous malformation is estimated to be around one case per 10,000 population. Conclusions: An updated estimate, more accurate than those previously published, of the prevalence of vascular malformations has been obtained.

An error estimate for finite element approximation to elliptic PDEs with discontinuous Dirichlet boundary data

This note provides an error estimate for finite element approximation to elliptic partial differential equations (PDEs) with discontinuous Dirichlet boundary data. Solutions of problems of this type are not in H1 and, hence, the standard variational formulation is not valid. To circumvent this difficulty, an error estimate of a finite element approximation in the W1,r(Ω) (0<r<2) norm is obtained through a regularization by constructing a continuous approximation of the Dirichlet boundary data.

The Finite Element Method of High Degree of Accuracy for Boundary Value Problem with Singularity

Mathematical models of fracture physics and mechanics are boundary value problems for differential equations and systems of equations with a singularity. There are two classes of problems with a singularity: with coordinated and uncoordinated degeneracy of the input data, depending on the behavior of the coefficients of the equation. Finite element methods with the first order of convergence rate O(h) have been created to find an approximate solution to these problems. We construct a scheme of the weighted finite element method of high degree of accuracy for the boundary value problem with uncoordinated degeneracy of the input data and singularity of the solution. The rate of convergence of an approximate solution of the proposed finite element method to the exact Rν-generalized solution in the weight set W2,ν+β2+21(Ω,δ) is investigated. The estimation of finite element approximation O(h2) is established.

Corrosion Resistance of Zinc and Zinc-Aluminum-Magnesium Coatings in Atmosphere on the Territory of Russia.

Zinc-coated carbon steel is commonly used in the construction of buildings, infrastructure objects such as roads and bridges, automotive production, etc. Coatings based on zinc-aluminum-magnesium alloys that may have better corrosion resistance than zinc have been developed. The coatings made of the new alloys have been available on the market for a shorter period of time than conventional zinc coatings. This paper presents data on the corrosion resistance of zinc and zinc-aluminum-magnesium coatings on carbon steel obtained by tests in four locations in Russia with marine and non-marine atmospheres. Four one-year exposures at the beginning of each season and two-year tests were performed. It is shown that the corrosion resistance of the coatings depends significantly on the beginning of the exposure. The categories of atmosphere corrosivity in relation to the coatings were determined at each location. Based on the dose-response function (DRF) for zinc developed for the territory of Russia, DRFs for the coatings were obtained. A match between the categories of atmosphere corrosivity determined by the first-year corrosion losses and estimated from the values of corrosion losses calculated using the DRF is shown. Based on the data of two-year tests, the variation in the corrosion rate over time is obtained. The corrosion rates of the coatings in the territory of Russia are compared to the corrosion rates of coatings observed in various locations around the world. An approximate estimate of the service life of the coatings at the test sites is given.