High Probability Of Failure Research Articles

Landmark Topology Descriptor-Based Place Recognition and Localization under Large View-Point Changes.

Accurate localization between cameras is a prerequisite for a vision-based heterogeneous robot systems task. The core issue is how to accurately perform place recognition from different view-points. Traditional appearance-based methods have a high probability of failure in place recognition and localization under large view-point changes. In recent years, semantic graph matching-based place recognition methods have been proposed to solve the above problem. However, these methods rely on high-precision semantic segmentation results and have a high time complexity in node extraction or graph matching. In addition, methods only utilize the semantic labels of the landmarks themselves to construct graphs and descriptors, making such approaches fail in some challenging scenarios (e.g., scene repetition). In this paper, we propose a graph-matching method based on a novel landmark topology descriptor, which is robust to view-point changes. According to the experiment on real-world data, our algorithm can run in real-time and is approximately four times and three times faster than state-of-the-art algorithms in the graph extraction and matching phases, respectively. In terms of place recognition performance, our algorithm achieves the best place recognition precision at a recall of 0-70% compared with classic appearance-based algorithms and an advanced graph-based algorithm in the scene of significant view-point changes. In terms of positioning accuracy, compared to the traditional appearance-based DBoW2 and NetVLAD algorithms, our method outperforms by 95%, on average, in terms of the mean translation error and 95% in terms of the mean RMSE. Compared to the state-of-the-art SHM algorithm, our method outperforms by 30%, on average, in terms of the mean translation error and 29% in terms of the mean RMSE. In addition, our method outperforms the current state-of-the-art algorithm, even in challenging scenarios where the benchmark algorithms fail.

Reliability modeling for balanced systems considering mission abort policies

This paper studies a mission abort policy to avoid the high probability of system failure for a balanced system performing a specific mission continuously over a period of time. The system comprises two subsystems with multiple states, and a balance criterion proposed in this paper is based on the state distance between the two subsystems. A mission abort policy is implemented when the system enters into unbalanced subsets reaching a limited number of times. The system is considered to have failed if one of the subsystems enters into an absorbing state. To assess the system's performance, two probability indices, namely mission success probability and system survivability, are derived by using the theory of aggregated stochastic processes. To validate the findings presented in this paper, a case study involving an unmanned aerial vehicle performing a mission is conducted. The results of this case study effectively demonstrate the efficacy of the proposed mission abort policy and the derived probability indices.

Readiness level assessment for lean Six Sigma implementation in the healthcare sector

PurposeThe purpose of this study is to identify the critical readiness factors (CRFs) that mainly affect the implementation of Lean Six Sigma (LSS) in an organization and their interactions, and to develop a model that allows the management to assess the Lean Implementation Readiness Level.Design/methodology/approachThe methodology is separated into two main parts: the literature review and the assessment model development. In the literature review, the main CRFs and their interactions for LSS implementation in Scopus Data Base were identified. The second part of the methodology is the model development. It was built on a stepwise framework that considers the relations among the CRFs and their importance. Moreover, it was used fuzzy-based linguistic variables given by the experts working in the company to consider the actual performance rating of each CRF. The model has been validated in the healthcare sector in nine hospitals.FindingsFrom the model application, it is possible to note that the most frequent level among the nine hospitals interviewed is “Average Ready”. Also, the most extreme level of readiness occurred ones while the most extreme level of not readiness never occurred. Results show that in 78% of the cases, there would have been a high probability of implementation failure. Also, it was possible to identify for each hospital if the CRFs are good, if they are weak and need to change or if another factor needs to be improved before it and what this factor is.Originality/valueThis work proposes a new methodology that eliminates the negative aspects and limitations of the total interpretive structural modeling methodology and the fuzzy logic approach currently applied to evaluate the LSS readiness of a company. The present methodology lies in the fact that it provides a solution not only by defining the weak CRFs but also by giving an indication of priority as it identifies the weak antecedent factors that inhibit the preparedness of the depending factors.

Improved support point selection on adaptive kriging metamodels for reliability analysis of soil slopes

The paper presents an iterative approach based on stochastic simulations and adaptive Kriging metamodels to perform reliability and safety assessments of soil slopes. Two new rules for adaptively selecting support points are proposed, considering an entropy learning function and the closeness to the failure domain defined by a limit state function. In addition, a stopping criterion is proposed based on root-mean-square and mean absolute percentage errors computed with cross-validation at the local level, focusing on regions where the uncertainties are relevant. Finally, the selection rules for support points and the error metrics are implemented in two benchmark problems with a low, moderate, and high probability of failure. Ultimately, the work leads to an adaptive Kriging strategy for slope stability assessment, offering: (1) a fair comparison with other strategies based on a significant number of realizations, (2) a stopping criteria based on a new local error metric, (3) an insight of the behavior across different magnitudes of the probability of failure, and (4) a new selection rule that reduces the total number of support points significantly. The proposed scheme is easily paired with commercial software to compute support points, resulting in an attractive tool for practitioners.

Development of Methods for an Overhead Cable Health Index Evaluation That Considers Economic Feasibility

To supply stable and high-quality power according to the advancement of industrial growth, electric power companies have performed maintenance of power facilities using various methods. In the case of domestic power distribution facilities, there are limitations in performing diagnostic management on all facilities owing to the large number of facilities; therefore, old facilities are managed using the health index assessment method. The health index assessment comprises only facility operation data and external environmental data and is managed only for four types of distribution facilities including overhead/underground transformers and switchgears. In the case of high voltage overhead lines, there are a large number of wires such as transformers and switchgears connected to the lines, and the ripple effect of power outages is large. However, in Korea, there is no overhead line health index standard. In overseas cases, a health index for overhead lines was developed, but only the material characteristics and surrounding environment of the overhead lines were considered and economic feasibility was not considered. Therefore, in this paper, we developed a health index evaluation methodology for ultra-high voltage overhead lines that considers economic feasibility. In this paper, unlike the existing health index evaluation method that uses only operational data and external environmental data to determine facility performance evaluation and aging replacement standards, we developed an economic health index evaluation methodology that additionally considers failure probability and risk costs. Using the health index assessment methodology developed in this paper, it is possible to expect a reduction in facility operating costs and investment costs from the perspective of the electric power companies through the replacement of old extra-high voltage overhead cables. In addition, from the perspective of consumers, it is expected to increase power reliability and reduce the ripple effect of failure by preferentially replacing equipment with a high probability of failure.

Open-Circuit Fault Analysis and Recognition in Three-Level Inverters Based on Recurrence Plot and Convolution Neural Network

Power electronics is vital to modern infrastructure, but it is susceptible to open-circuit faults that can cause serious damage. Three-level inverters are commonly used in such equipment, but their high sensitivity and probability of failure make them particularly challenging to diagnose. In this groundbreaking study, we present a new method for accurately detecting and locating open-circuit faults in three-level, neutral-clamped inverters. Using advanced simulation tools and nonlinear dynamic methods, we develop a new diagnostic model that outperforms existing fault classification algorithms. By converting the current signal into an unthreshold recurrence plot (URP) and mapping its nonlinear features to a two-dimensional plane, it is possible to extract key spatial information and train a residual neural network model for fault diagnosis. The method represents a major advance in power electronics and has the potential to save equipment from costly damage. By accurately detecting and locating open-circuit faults in three-level inverters, the reliability and safety of power electronics can be guaranteed for years to come.

Stability and probabilistic assessment of a large asymmetric bedding slope with a weak interlayer.

The mining of open-pit mines has a significant influence on the surrounding ecological environment and safety. Once the slope of an open pit is unstable, it will bring extremely severe disasters to the surrounding environment. The south slope of the Fushun West open-pit mine is a large bedding slope with weak interlayer and asymmetrical features between the eastern and western regions. The different deformation mechanisms are worth further discussion, and the deformation mechanism of the eastern region needs to be systematically investigated. In this study, a comprehensive method combining a numerical model, the limit equilibrium method, and a probabilistic approach is used. The different deformation mechanisms of the slope are explored. Thereafter, the sensitivity of the geometric and mechanical parameters of the slope is determined. Finally, the probability of failure (PF) and slope stability are evaluated. The results illustrate that the difference in geological characteristics and constraint conditions is the fundamental reason for the difference in deformation features of the slope. The sensitivity analysis results show that the friction angle of the weak layer exhibits the most sensitivity and that the unit weight is irrelevant to the slope stability. Taking the friction angle of the weak layer as a variable, when thethickness of the basalt layer is less than 140 m and the height of the slope is more than 360 m, the PF of the slope reaches a high value. When the inclination of the weak layer exceeds 30°, the PF of the slope increases to a high value. When the Ru coefficient exceeds 0.2, the slope presents a high PF. The results illustrate that decision-makers should pay attention to the strength degradation, transitional mining of the basalt layer, and establish a good drainage system. The comprehensive method can also provide an effective way to assess the stability and PF of similar large-scale bedding slopes under complex geological conditions.

Population expansion and intensification from a Malthus-Boserup perspective: A multiproxy approach in Central Western Argentina

In Central Western Argentina (CWA), the incorporation of cultigens by hunter-gatherer populations has been much discussed. This paper explores the relationship between population dynamics, subsistence change, and burial patterns driven by the process of land use intensification and increasing reliance on maize. We hypothesize that territorial behavior emerged in the context of population growth and competition for resources with a high probability of failure, as expected in an arid environment. To evaluate this hypothesis, we explore four lines of inquiry in southern Mendoza (CWA): 1) the frequency of radiocarbon dates to estimate population dynamics; 2) the Juvenile Index as a fertility rate proxy; 3) the stable isotopes on human bone (δ13Cco, δ15N, δ13Cca) to reconstruct diet; and 4) burial patterns as an estimate of territorial control. Our results partially support our hypothesis: During an early stage, when maize started to appear in the diet, the population was increasing, and cemeteries emerged along with some signs of violence. The hypothesis is not supported in a second period, when maize consumption and population were highest, but large cemeteries disappeared. In light of this evidence, the effect of maize on human societies was not uniform and irrevocable, and the adoption of maize by human foragers contributed to a new and diverse set of human-environment relationships.

Experimental study and numerical analysis of thermal hazard for fire accident in converter transformers

Converter transformers are widely used in high voltage direct current (HVDC) transmission systems. Due to its large storage capacity and relatively high failure probability of the insulation, pool fires are a common type of accidents for this type of transformers, which could pose a significant threat to the safety of personnels and the integrity of nearby transformers. During normal operation, the temperature of the transformer oil can vary between 80 and 90 °C. It is known that the oil temperature can have a significant impact on its burning characteristics. However, most of previous simulations of transformer fires utilized the material properties of transform oil obtained at ambient temperature to determine the heat release rate (HRR). In this study, experimental data (D = 0.2–1.0 m) at an initial oil temperature of 85 °C were employed to determine the correlation between HRR and burner diameter, which was subsequently used to validate the numerical model. 14 typical fire scenarios were examined to understand the accident development process of transformer pool fires. The results showed that a merged flame was observed at the inner side for the case when the fire occurred both on the oil tank upper surface and in the oil storage pit. The radiation impact on (and thus the risk of failure of) key transformer components was found to vary considerably across the different fire scenarios. The radiative heat flux at the outlet of the enclosure where the fire is located was found to exceed 5 kW/m2 and the recommended safety distance for firefighting can reach 6.6 m. It was also found that the maximum heat radiative flux received by the high voltage bushing of an adjacent transformer can reach 46.2 kW/m2 in the worst-case scenario, with a probability of escalation to the adjacent transformer approximately 3.50×10−4. Three distinctive areas (safety area, risk area, and dangerous area) were identified to determine firefighting positions and strategies for transformer substation fires. The present results could not only enhance the understanding of the accidental development of converter transformer fires but also provide valuable guidance in firefighting in various fire accident scenarios.

Голографическая фотонная система фазовой синхронизации в спутниковом радиоканале

A necessary condition for the qualitative solution of telecommunication, infocommunication and navigation tasks in satellite communication systems is the presence of a high-precision synchronization system in satellite radio channels. It is indicated that the operation of the data exchange synchronization system in satellite radio channels is adversely affected by a number of external factors, such as, for example, the presence of the Doppler effect, errors in determining the relative speeds and directions of movement of artificial Earth satellites (ISS), the presence of a delay time of the transmitted signal due to significant distances between the nodes of the satellite communication network. The main disadvantages of modern synchronization systems used in satellite radio channels are given, and it is concluded that there is a relatively high probability of synchronism failure. It is indicated that the primary type of synchronization in a satellite radio channel is phase synchronization, the errors of which affect all subsequent types of synchronization (clock, frame and cycle). Analysis of the technical characteristics of modern phase synchronization systems in satellite radio channels allowed us to conclude that it is urgent to search for a new approach to the construction of these systems, which provides an increase in the speed and accuracy of their works. A possible way to solve this problem is the use of holographic photonics elements based on holographic sensing elements in measuring equipment that ensures the functioning and synchronization of satellite radio channels. The article solves the problem of constructing a holographic photonic phase synchronization system in a satellite radio channel. A technical solution is proposed to increase the speed, sensitivity and accuracy of the phase synchronization system by using a volumetric reflective Fourier hologram in the design of this system. A variant of the block diagram of the holographic photonic phase synchronization system is developed and the operation of this scheme is described. The constructive construction of optical elements of the developed block diagram in the form of electro-optical modulators and deflector optical systems is proposed. The individual features of the construction of these structural elements are indicated. The functional purpose of a volumetric reflective Fourier hologram in the design of a holographic photonic phase synchronization system is formulated. The regularities of changes in the parameters of optical fields in the holographic photonic elements of the phase synchronization system of a satellite radio channel are investigated. Concrete numerical examples demonstrate the possibility of providing high sensitivity and accuracy of a holographic photonic phase synchronization system.

Evaluating the likelihood of slope failure in ageing earthworks using Bayesian updating

Earthwork assets, including cut slopes and embankments, are essential components of the infrastructure supporting road and rail transportation networks. Asset owners must assess the stability of these slopes as they deteriorate, to prevent unwanted slope failures. Assessing the stability of individual earthworks within a portfolio using slope stability analyses can be expensive and time consuming. Hence, a Bayesian logistic regression model was developed to evaluate the probability of slope failure, using training data from published case histories of slope failures. The Bayesian model was then used to assess the probability of failure for the more specific case of clay cut slopes within a railway earthwork asset portfolio owned by Network Rail (NR) in the UK. The portfolio includes earthworks at various stages of degraded strength and with different drainage conditions. The results from models with material properties that were equivalent to those for the deteriorated strength of clays compared most closely with clay cut slope failures within the NR data set. Steeper slopes (>35°) had the highest probability of failure, regardless of slope height, and drainage condition. However, for shallower slopes, poorly drained slopes had a ≈20% higher probability of failure than well-drained slopes.

Application of scaled boundary finite element method in failure probability estimation of square nanographene sheet

In recent years, so much attention has been drawn to the field of nano computational material science. Due to the extensive applications of nanographene sheets in various industries such as aerospace industry, fracture analysis of square nanographene sheets is of crucial importance. Stochastic analysis is widely applied in fracture mechanics because it helps the results to be more realistic. In the present work, probabilistic fracture analysis of nanographene sheets is done using scaled boundary finite element (SBFEM) that is a novel semi-analytical method. In order to apply the stochastic method, we need to select certain statistical parameters, the ones considered here include crack length and failure stress. The results using the stochastic response method are compared with those of the Monte Carlo, which shows good agreement. Average, variance, third and fourth moments of stress and the fracture probability are calculated for all the bonds in two states of crack angle 0°, 90°. The results indicate that the maximum crack-tip fracture probability for central crack θ = 90° is 95%, while for θ = 0° equals 58%. For central crack θ = 90°, the failure probability in crack tip bonds, bonds adjacent to the crack edge and other bonds equal 95%, 88% and 65%, respectively. For nanographene sheet having the central crack θ = 90°, probabilistic density function is Gaussian, which reaches the highest point at the displacement being 0.990 pm. The third moment of the stress turned out to be zero, which shows that the input uncertain variables are all normal. The results obtained from computing the failure probability of all the bonds indicates that the highest failure probability is in the tip and edges of the crack. The stochastic fracture sensitivity versus crack length is calculated which shows that the maximum sensitivity in central crack happens when θ = 90° and crack length ranges between 0.3 and 0.4.

A novel PEGylated form of granulocyte colony-stimulating factor, mecapegfilgrastim, for peripheral blood stem cell mobilization in patients with hematologic malignancies.

The Pegylated recombinant human granulocyte colony stimulating factor (PEG-rhG-CSF) has longer half-life and is given once only, which is more comfortable for patients. We aimed to evaluate the efficacy of mecapegfilgrastim for hematopoietic stem cell (HSC) mobilization in patients with hematologic malignancies and to explore the potential factors related to HSC mobilization. A retrospective analysis was performed on patients who underwent HSC mobilization in the hematology department of Mianyang Central Hospital from April 2016 to November 2022. The number of CD34 + cells collected was compared between the patients receiving mecapegfilgrastim (PEG group) and those receiving recombinant human granulocyte colony-stimulating factor (rhG-CSF group), and the possible factors for mobilization failure were analyzed. The success rates of collecting CD34 + cells in the PEG group and rhG-CSF group were 80.6% and 67.7%, respectively (χ = 1.444, P = 0.229). The median CD34 + cell counts were 3.62 × 10^6/kg and 2.92 × 10^6/kg (P = 0.178), respectively. After combination with plerixafor for mobilization, the median number of CD34 + cells collected in the PEG group and rhG-CSF group were 3.64 × 10^6/kg and 3.92 × 10^6/kg, respectively, with no significant difference (P = 0.754). There was no significant difference in hematopoietic cell recovery or infection between the groups (P > 0.05). Multivariate analysis showed that more than 5 cycles of chemotherapy (OR = 15.897, 95% CI: 1.766-143.127, P = 0.014), a precollection WBC count < 32 × 10^9/L (OR = 14.441, 95% CI: 2.180-95.657, P = 0.006) and a precollection to premobilization lymphocyte ratio < 1.7 (OR = 11.388, 95% CI: 2.129-60.915, P = 0.004) were independent risk factors for HSC mobilization failure. The HSC mobilization efficacy of mecapegfilgrastim in patients with hematologic malignancies was comparable to that of rhG-CSF, and combination with plerixafor for mobilization was feasible and effective. Patients with more than 5 cycles of chemotherapy before HSC mobilization, a precollection WBC count lower than 32 × 10^9/L, and a precollection lymphocyte count less than 1.7 times the premobilization lymphocyte count have a high probability of HSC mobilization failure.

Effect of slab stiffness on floor response spectrum and fragility of equipment in nuclear power plant building

The floor response spectrum (FRS) is used to evaluate the seismic demand of equipment installed in nuclear power plants. In the conventional design practice of NPP structure, the FRS is simplified using the lumped-mass stick model (LMSM), assuming the floor slab as a rigid diaphragm. In the present study, to study the variation of seismic response in a floor, the FRSs at different locations were generated by 3-D finite element model, and the response was compared to that of the rigid diaphragm model. The result showed that the FRS significantly varied due to the large opening in a floor, which was not captured by the rigid diaphragm model. Based on the result, seismic fragility analysis was performed for the anchorage of a heat exchanger, to investigate the effect of location-dependent FRS disparity on the high confidence low probability of failure (HCLPF).

Influence of intrinsic variability in anthropic slopes

Anthropic slopes are common in constructing embankments and earth dams and forming open pit mines and fills, among others. However, these slopes artificially built sometimes could fail due to the variability of the soils, lack of expertise in determining the design parameters, and lack of knowledge of the soil’s true behavior and construction methods, among others. To address these problems, physical models were made in a geotechnical centrifuge with similar characteristics to study the effect of variability. Subsequently, Monte Carlo simulations were performed using finite element models (FEM) with random geotechnical parameters for an elastic model with Mohr-Coulomb failure criteria. From these simulations, the influence of geotechnical parameters on the factor of safety and deformations was observed. The results show that the coefficient of variation obtained for the factor of safety was less than the coefficient of variation of the geotechnical parameters taken into account. This means that the coefficient of variation of the factor of safety is not the sum or the average of the coefficients of variation taken in the analysis. However, when the factor of safety is more or less constant, but the coefficient of variation of the parameters increases, the probability of failure may increase. This shows that a slope with a factor of safety greater than one can have a high probability of failure. In addition, low friction angle and low cohesion values tend to present more significant slope crest displacements.

Detecting landslide vulnerability using anisotropic microtremors and vulnerability index

The vulnerability of the Nan-Shi-Keng landslide area in Taiwan is investigated via single-station horizontal-to-vertical spectral ratio analysis. The measurement stations in the area are arranged as follows: (1) a transverse arrangement through the landslide site along Highway No. 175 (Case 1) and (2) two longitudinal arrangements down the slope (Case 2). In Case 1, the distribution of the vulnerability index along the highway indicates that the risk of surface deformation is high on sections of the highway located outside the potential sliding zone. The low vulnerability index of highway sections within areas where the protection measures have been taken indicates that they successfully stabilize the highway and the upper slope area. In Case 2, the deformation-prone directions (i.e., the directions with the maximum vulnerability index) evaluated at various stations using anisotropic microtremor measurements of the landslide site correlate strongly with the local sliding directions obtained using conventional inclinometer measurements and telemetry monitoring. The value of the vulnerability index is related to the highway damage and soil movement behavior. Therefore, the vulnerability index serves as a useful warning parameter to locate sites with a high probability of slope failure.

Ultrasound findings to predict failure of conservative treatment in the appendix testis torsion

BackgroundTorsion of the appendix testis (TAT) is considered the most common cause of acute scrotum in childhood. When clinical and ultrasound (US) findings agree with the diagnosis, after testicular torsion has been excluded, conservative therapy is attempted whereas scrotal exploration and removal of the hydatid are required when medical therapy has failed. We hypothesized there are US features that can predict the failure of conservative therapy.MethodsWe conducted a retrospective analysis on pediatric patients treated for TAT. The age of patients, number of days spent with symptoms before the start of treatment, presence of epididymitis and/or hydrocele, and dimension of the twisted hydatid were analyzed. A search for a correlation between these variables and failure of conservative treatment was conducted.ResultsPatients were divided into 2 groups based on the efficacy of conservative management: responders (group I) and non-responders subjected to surgical treatment (group II). No statistically significant differences were registered in regard to age (p = 0.25), average dimension of hydatid (p = 0.09), and time gap between symptoms and the start of therapy (p = 0.92) between the 2 groups. An associated epididymitis was described in 27.5% of patients in group I and 41.7% in group II (p = 0.03; OR 1.89), and associated hydrocele was described in 33.4% of patients in group I and 45.8% in group II (p = 0.03; OR 1.83). Considering the odds ratios, the probability of surgical intervention when presenting only epididymitis without hydrocele is estimated to be 15%, when presenting only hydrocele without epididymitis: 9%, with both epididymitis and hydrocele: 74%, and without epididymitis nor hydrocele: 2%.ConclusionsThe presence of both epididymitis and hydrocele at first US evaluation is associated with a high probability of conservative treatment failure, thus predicting the need for surgical intervention.

Assessment of the reliability оf operation of water purification system units in transitional modes

Ensuring uninterrupted and reliable operation of water treatment systems is a priority task of the industrial complex of Ukraine. For effective reliability management in water treatment systems, it is necessary to analyze potential failures and determine the probability of their occurrence. For the purpose of research to determine the probability of the occurrence of risks as a result of failures of various units of the water purification system, using the example of the operation of a column-type electrocoagulator, it is proposed to use the structural and functional block diagram of water purification systems to obtain generalized patterns, which makes it possible to reduce the entire system to several interdependent units, namely: 1) fine-cleaning filtration unit; 2) a unit for cleaning from soluble impurities; 3) a unit for cleaning coarse impurities; 4) pipe-pump unit. When the water treatment system is operating, taking into account the ranking of the reliability of the units, it can be stated that the 1st unit may fail at the beginning, followed by the 2nd, 3rd and 4th units. It is established that if all the units of the system are working, the system is in the S0 state. When other blocks fail, in the same sequence, the system will be in states S1, S2, S3 and S4. The most interesting are the states of the system, in which block failures do not cause shutdown of the entire system, but only its off-duty operation, which is manifested only as a result of the deterioration of the quality of treated water. Analyzing the obtained results, it can be asserted that during the operation of the water treatment system, the highest probability of failure is in unit 1. After the unit is restored and during further operation of the system, the highest probability of failure is unit 2, then unit 4 and unit 3. The failure probabilities of the units are the probabilities of risks, moreover, the physical value generated by these risks (the amount of polluted water that entered the ecosystem or the boiler unit) will be greater, the longer the unit failure detection period. When the water treatment system operates for a long enough time, a probabilistic constant mode of transition from state to state is established in it according to the scheme «working state of all blocks - failure of one or several blocks - repair - working state of all blocks». The probability of the sequence and duration of these events can be determined, which makes it possible, on the one hand, to assess the risks arising during operation and to determine a management strategy to minimize these risks.

Treatment strategy for venous congestion in digit replantations

With microsurgical techniques, digit replantation becomes a treatment option for amputated injuries. By standard, the survival of replants relies on satisfactory artery reconstruction and venous drainage to restore tissue perfusion. The main reason for replantation failure is the improper treatment of venous congestion during the critical postoperative period. Surgical re-exploration and emergently redoing digital vein reconstruction are conventional in treating this threatening condition. As this procedure demands the patient’s surgical preparation and immediate availability of surgical crews or facilities, any treatment delay and prolonged congestion could result in a higher failure probability.

Simulation Failure-Robust Bayesian Optimization for Data-Driven Parameter Estimation

Advances in modeling and computation have resulted in high-fidelity digital twins capable of simulating the dynamics of a wide range of industrial systems. These simulation models often require calibration, or the estimation of an optimal set of parameters in some goodness-of-fit sense, to reflect a system’s observed behavior. While searching over the parameter space is an inevitable part of the calibration process, simulation models are rarely designed to be valid for arbitrarily large parameter spaces. The application of existing calibration methods, therefore, often results in repeated model evaluations using parameters that can cause the simulations to be impractically slow or even result in catastrophic failure. In general, the shape of subregions in the parameter space that could result in simulation failure is unknown. In this article, we propose a novel failure-robust Bayesian optimization (FR-BO) algorithm that learns these failure regions (FRs) from online simulations and informs a Bayesian optimization algorithm to avoid FRs while optimizing model parameters. This results in acceleration of the optimizer’s convergence and prevents wastage of time trying to simulate parameters with high failure probabilities. The effectiveness of the proposed FR-BO algorithm is demonstrated via a well-known benchmark example where we compare against state-of-the-art gradient matching techniques, and a practical example related to parameter estimation for digital twins of buildings.