Overload Risk Research Articles

Traffic Hazards on Main Road’s Bridges: Real-Time Estimating and Managing the Overload Risk

Traffic Hazards on Main Road’s Bridges: Real-Time Estimating and Managing the Overload Risk

Transoral laser exoscopic surgery of the larynx: state of the art and comparison with traditional transoral laser microsurgery.

To evaluate the efficacy of transoral laser exoscopic surgery (TOLES) in a unicentric series of patients affected by benign and malignant glottic and supraglottic lesions, and compare outcomes with those of transoral laser microsurgery (TOLMS). To demonstrate the non-inferiority of TOLES in terms of operative time, margin status and complication rates, we compared outcomes of 93 patients treated by TOLES between July 2021 and July 2023 with those of a match-paired group of 107 historical patients treated by TOLMS. To perform a multiparametric ergonomic evaluation of TOLES vs TOLMS, we used observational methods for biomechanical overload risk assessment and wearable technologies comparing 15 procedures with TOLES vs a paired match of 13 surgeries performed with TOLMS by the same surgeon. No significant differences were found in terms of surgical duration, positive margins, or complications between TOLES and TOLMS. Ergonomics assessment by inertial measurement units and electromyographic surface electrodes demonstrated a reduced biomechanical overload with TOLES compared to TOLMS. The many advantages of TOLES, such as its superior didactic value, better digital control of light even through small-bored laryngoscopes, improved binocular vision, and increase in surgical performance by 3 or 4-hand techniques, are difficult to be quantified. In contrast, its non-inferiority in terms of oncological results and better ergonomics compared to TOLMS are demonstrated herein.

Power transformer overload risk evaluation based on temperature rise simulation and fuzzy analytic hierarchy process

The evaluation of transformer overload risk and operational safety is a systematic process. Selecting an appropriate method to accurately assess its overload operation risk is an urgent need for flexible control and safe and reliable operation of power systems. According to the thermal characteristics and state of the transformer, a method for evaluating the overload risk of transformers with improved accuracy based on temperature rise simulation calculation combined with the Fuzzy Analytic Hierarchy Process (FAHP) is proposed. The weights are calculated by fuzzy set theory and FAHP, and the overload risk of the transformer is finally determined. The method comprehensively considers the possible information conflict between the working condition data and the thermal characteristics of the structure itself, and the calculation results are accurate and the process is clear. The calculation results after substituting the actual data show that the method can accurately evaluate the overload risk and operational risk of the transformer. This method is beneficial to identify the relative importance of transformer overload risk factors, calculate transformer overload risk coefficients, and formulate transformer risk control methods.

A method for the risk assessment of biomechanical overload in hospital physiotherapists.

In physiotherapists, biomechanical overload risk assessment (RA) is particularly complex due to the tasks' variability. The present study aims to propose a new methodology, named Whole Body RA Biomechanical Overload (WB-RAMBO), to assess the risk in the activities performed by physiotherapists. Each type of intervention was broken down into elementary operations. The risk factors (force, repetitiveness, and incongruous postures) were recorded and evaluated for each of these. For each task, the risk level was obtained by integrating the results of multiple ergonomic methods among those proposed by the international literature. To verify and validate the obtained results, we reviewed the medical records of health surveillance carried out on physiotherapists. From the ergonomic point of view, RA shows a situation of acceptability. The observed slight dysergonomies are diluted in the work shift and allow an optimal functional recovery of the musculoskeletal system. This method proposes a RA for each operation performed. A work plan subjected to such a peculiar RA can be redesigned and adapted to the company's and the hypersusceptible worker's organizational needs.

Distribution Line Load Predicting and Heavy Overload Warning Model Based on Prophet Method

The load prediction of distribution network lines and the accurate prediction of impending overload lines can provide an important reference for the formulation of the power supply plan of distribution networks. This paper designs a line load predicting and heavy overload early warning model based on the Prophet method, where the time series decomposition and machine learning technologies are used. Firstly, we used the 5-day moving average to automatically fill the missing values in the data and automatically detect and correct the abnormal values in the data. Then, we decomposed the prediction model into the trend component, periodic component, and data mutation component by fully considering the periodicity, seasonality, holidays, and other factors of power data, which effectively improves the prediction accuracy and gives early warning of potential heavy overload risk. Finally, we tested the model according to the processing speed, root-mean-squared error (RMSE), recognition accuracy, and overload warning hit rate. The results showed that the model obtained in this paper has high accuracy and practicability.

Online Reviews and Information Overload: The Role of Selective, Parsimonious, and Concordant Top Reviews

By empowering customers to make fitting purchases, user reviews play an important role in reducing inefficiencies in the provisioning of product information. Because of the abundance of reviews and the signals they provide, this information may become confusing and risks overloading customers. Consequently, review hosting platforms have adjusted their designs to feature a signal “distilled” from a selective set of “top reviews” and their valences. The expected ease with which customers process this signal is intended to increase their satisfaction, thus reducing dispersion in their subsequent review ratings. In this study, we analyze the influential role that top reviews and their valence play under various scenarios: when customers are overloaded by a large number of reviews, when top reviews themselves are not parsimonious in number, and when the signals from top reviews are not in concordance with that from all the other reviews. We find that the valence of top reviews plays a central role in mitigating information overload. However, the influence of those top reviews diminishes when they too pose an overload risk but is strengthened when their signal is reaffirmed by signals from all other reviews. Finally, the impact of top reviews is weaker for less popular products.

Transmission Line Overload Risk Assessment Considering Dynamic Line Rating Mechanism in a High-Wind-Penetrated Power System: A Data-Driven Approach

The dynamic line rating (DLR) can be an effective mechanism that reduces wind curtailment induced by line congestion considering its unique correlation to wind speed. However, the calculation of the DLR depends on accurate environmental parameters, which can be challenging in look-ahead decision-making applications. Consequently, transmission line overload risk (TLOR) can exist. In this paper, we propose a two-stage TLOR assessment model for high-wind-penetrated power systems considering the DLR. An overload risk index along with the risk-averse line capacity bound (RAB) for each line can be obtained from the proposed model. Meanwhile, a computationally efficient data-driven approach that combines convex-hull and box-like modeling methods is established to characterize the uncertainty during the decision-making process. The proposed model is solved by a modified column-and-constraint generation (C&CG) algorithm, and its effectiveness and scalability are illustrated by multiple simulation experiments.

Cooperative overload control strategy of power grid-transformer considering dynamic security margin of transformer in emergencies

With the integration of large-scale renewable energy resources and growth of electricity demand, the peak-to-valley load difference increases constantly. The overload risk of transformer in emergencies is enlarging, which urgently requires cooperative control of power grid-transformer to avoid catastrophic accidents. Thus, a cooperative control strategy of power grid-transformer considering the dynamic security margin of the transformer in emergencies is proposed in this paper. First, the safety domain model of the transformer is constructed based on the temperature rising model as well as insulation deterioration pattern, and the dynamic security margin of the transformer is evaluated accordingly. Then, targeted counter measures are selected according to the safety status of the transformer, and different control schemes such as emergency overload, topology adjustment, and load shedding are generated by solving the optimization model. Finally, the effectiveness of the proposed strategy is validated in various scenarios. The results show that when the security margin of transformer is sufficient, the strategy can fully exploit its overload capability to support grid regulation and avoid premature load shedding; when the security margin is insufficient, load shedding is coordinated to ensure the security of transformer. The proposed strategy can realize the synergistic control and mutual support between power grid safety and equipment safety.

Adaptive Droop Control of the VSC-MTDC Distribution Network Considering Power–Voltage Deviation

In order to realize the unbalanced power optimally allocated and the DC voltage stably controlled after disturbance, an adaptive droop control method considering power and voltage deviation is proposed based on the traditional voltage–power droop control of a voltage source converter-based multi-terminal direct current (VSC-MTDC) distribution network. The inherent constraint that the unbalanced power is proportionally distributed according to its capacity under the traditional droop control is broken in the proposed method to realize the reasonable transfer of unbalanced power and to reduce the overload risk of smaller capacity VSCs; the “dead zone” is appropriately set to relax the operating range of the VSC to a certain extent by a power deviation factor being introduced in the droop characteristic curve. The corresponding MATLAB/Simulink simulation model of the five-terminal DC power distribution network is established and compared with the electromagnetic transient model under the traditional droop control. Finally, the simulation results verify the effectiveness and control effects of the proposed control method.

Biomechanical overload risk assessment in Industry 4.0

Biomechanical overload risk assessment in Industry 4.0

An Active Power Coordination Control Strategy for AC/DC Transmission Systems to Mitigate Subsequent Commutation Failures in HVDC Systems

Subsequent commutation failures (CFs) in HVDC systems will cause large-scale power flow transfer in AC/DC transmission systems and lead to overload risk in HVAC systems. In order to cope with these effects, a power coordination control strategy for the AC/DC transmission system with high-proportion wind power is proposed. Firstly, a model of the AC/DC transmission system considering the large-scale wind farms access is established by analyzing the power transmission characteristics of the AC/DC transmission system with high-proportion wind power, and the power transmission characteristics are analyzed after subsequent CFs. Secondly, the HVDC subsequent CFs can be mitigated by adjusting DC power transmission, while the active power output of the sending-end AC system is reduced by active control of wind turbine generators (WTGs) to reduce the overload risk of the HVAC system. Finally, the proposed power coordination control strategy is simulated and verified based on the established simulation model and actual power grid, and the results show that this strategy can effectively mitigate HVDC’s subsequent CFs and reduce the overload risk in HVAC systems.

Power system vulnerability analysis based on topological potential field theory

Evaluating the vulnerability of power system effectively and accurately is of great significance for predicting cascading failures and preventing blackouts. Therefore, we propose a power system vulnerability analysis method based on the topological potential field theory in this paper. Firstly, according to the overload risk and operation risk of transmission lines in cascading failures, we construct a fault chain graph considering two-level cascading failures. Secondly, we define the generalized node quality, and then propose a power system vulnerability evaluation method based on the topological potential theory of the data field by using the network edge weights to quantify the node entropy degree. At the topological structure level, this method pays attention to the influence between lines and that of each line on the entire power system, which can more reflect the important lines in the power system accurately. Finally, we do vulnerability simulations on the IEEE-39 bus system and a certain regional power grid in China respectively. The results show that the method has higher identification accuracy and lower time complexity on the basis of ensuring the integrity of the power grid topology.

Emergency Control Strategy for Line Overload Considering Power Source and Load Fluctuation

Uncertain factors such as the integration of renewable energy into the grid and load fluctuations have brought more risks to the safe dispatch of the grid. The random power flow is used to calculate the impact of distributed power sources and load fluctuations on the grid, and to quantify the probability distribution of line power, which can avoid the drawbacks of deterministic power flow that cannot fully reflect the line overload risk. Combining the line overload level with the traditional load shedding method can effectively prevent the system from cascading failures caused by the risk of line overload, improve the optimistic calculation results caused by the load shedding strategy in emergency situations that cannot consider source load fluctuations, and make the grid control more safe and reliable.

Ergonomic analysis of biomechanical overloading: external coating activity using mortar

The economic growth of a country is directly linked to the growth of several sectors, in which the construction sector is prominent. The objective was to investigate by means of ergonomic analysis the external coating activity performed on building façades, due to its high degree of difficulty. The methodological approach was composed by a review of the literature and quantitative research using the OCRA checklist method, highlighting the biomechanical overload risk analysis of the external coating activity in mortar based on International Standard ISO 11228-3: 2009. The data collection took place in construction sites in Brazil in the cities of Ponta Grossa-PR and Porto Alegre-RS applying the mentioned method. The results of demand illustrate the concepts presented in the review, as well as the confirmation of the incidence of pain and lesions in the upper limbs and the repetitiveness in the analyzed activities. The results indicate that: a) the analysis of the chosen activity resulted in a high level of risk applying the immediate intervention, with improvements; b) proof by calculating the risk of biomechanical overload to implement improvements in the company; c) evidence that the improvements resulted in a reduction of ergonomic risks by more than 50%, with improvement in posture and strength requirements. In turn, the relevance of this work is highlighted, as it enables the development of public and private policies in the area of ergonomics with the purpose of developing the sector. In the end, the work opens up possibilities for the continuity of the research on the addressed topic.

Psychological burden of covid-19 health crisis on health professionals and interventions to minimize the effect: what has history already taught us?

Health professionals have been at the frontline of the health service since the outbreak of covid-19, responding promptly to diagnose, support and treat infected patients. World Health Organization (WHO) has already praised their contribution and their essential role in controlling this disease. Some of the main concerns of covid-19's impact to health service staff include work overload, exhaustion, and high risk of self-infection or transmission to family members. Moreover, during the pandemic, caregivers' mental health inevitably becomes vulnerable, with salient stress and anxiety-related symptoms. Uncertainty, fear of contagion, guilt, hopelessness, stigmatization and, in some cases, long-term post-traumatic stress disorder (PTSD) are few of the potential effects posed by this outbreak on health workers. In this review, lessons learnt from previous global crises or pandemics on the psychological impact of health workers are presented. History could potentially provide essential information on how to best manage, support and optimize our approach to this highly appreciated and much needed group of professionals. Targeted and prompt interventions could reduce the psychological strain of health professionals, thus, further improving provided patient care. Covid-19 is an on-going health crisis and this work, even though generated by limited existing data, could be used to inform governments and/or institutions and lead on decisions and changes in current guidelines.

Risk-Averse Stochastic Dynamic Line Rating Models

Static line rating (SLR), which is conventionally used in operation, not only results in a conservative usage of the capacity of overhead lines, but also fails to accurately address the overload risk. In this paper, using quantile regression (QR) and superquantile regression (SQR) methods, two models are proposed to predict dynamic line rating (DLR) of overhead conductors in operational applications with very short-term horizons. The proposed methods model statistical properties of time evolution of conductors considering the conductor thermal inertia to cope with situations with higher time resolutions for enhanced capacity usage. To address the overload risk due to forecast uncertainties of weather-related parameters, the proposed models are reformulated as risk-based constraints and utilized as QR and SQR-based DLR. The developed constraints are fully parametric and readily applicable to optimization problems and are verified through an optimal power flow (OPF). Results of examining the proposed models on the RTS test system confirm their efficiency in terms of better utilization of conductor capacity, increased energy transfer, and reduced risk levels.

A novel irrigation canal scheduling approach without relying on a prespecified canal water demand process

The creation of an efficient and environmentally friendly irrigation canal schedule strongly depends on the accuracy of the prespecified water demand (PSWD) process in existing scheduling practices and modeling studies. Overestimating water demand would result in spillage losses from over-irrigation, while underestimating water demand would lead to crop yield losses due to deficit water supply. However, prespecifying an accurate water demand often poses various challenges for both farmers and canal administrators, as it involves the temporal variability in agrometeorological conditions, the spatial diversity of soil properties, and the sensitivity of crops to water stress at different growth stages. Therefore, to reduce the uncertainty of prespecifying water demand and avoid the adverse effects of an inaccurate water demand on canal water allocation, this paper proposes an alternative canal scheduling model that maximizes canal scheduling service quality by targeting the ultimate objectives of the irrigation system (UOIS) without considering the prespecified water demand as the model input. The UOIS canal scheduling (UOIS-CS) model aims to optimize the canal water delivery schedule via simulation of soil water and salt migration using the Simultaneous Heat and Water (SHAW) model, to provide the most suitable soil moisture content and soil salinity for crops. The UOIS-CS model is used for the Hetao Irrigation District, Inner Mongolia, a typical agricultural watershed in China, where supplementary irrigation is performed after the autumn harvest (i.e., autumn irrigation) to leach excessive soil salt and preserve a moderate amount of soil moisture for the beginning of the next spring sowing period. To evaluate the irrigation performance of the UOIS-CS model further, a comparative analysis between the UOIS-CS model and the widely used PSWD-based canal scheduling (PSWD-CS) model is conducted. Compared with the PSWD-CS model, the proposed UOIS-CS model exhibits a superior irrigation performance in terms of leaching soil salt and preserving soil water, and a lower risk of canal overload operation during a higher water demand period. The improved performance of the UOIS-CS model is attributed to its greater adaptability to the spatial diversity of soil properties and the temporal variability in agrometeorological conditions, which originates from the full use of the equifinality of model performance metrics and model inputs. The UOIS-CS model provides managers with an effective approach to formulate a canal water delivery schedule with improved irrigation efficiency and lower overload risk. The proposed framework is generic and can be applied to non-crop growing seasons.

BIOMECHANICAL EVALUATION OF RECONSTRUCTED EXTENSIVE MANDIBULAR DEFECTS BY DIFFERENT MODELS USING FINITE ELEMENT METHOD

Rehabilitation of major mandibular defects after tumor resection has become a serious challenge for surgeons. In this research, four various models were designed to repair a critical mandibular lateral defect. Biomechanical behavior of the models was assessed by Finite Element Method. These models are including Fibular-Free Flap (FFF), Customized Prosthesis (CP), Tray Implant without Bone Graft (TI-wo-BG), and Tray Implant with Bone Graft (TI-w-BG). FFF is a subset of microvascular free flap technique in which some segments of patient’s fibula bone are used to restore mandibular defects. CP is a hollow and light prosthesis which is fabricated using Additive Manufacturing technology from Ti alloy powder. TI-wo-BG is similar to a crib which is designed according to the geometry of the patient’s mandible. TI-w-BG, in fact, is a TI-wo-BG which is filled with small cortico-cancellous chips in order to benefit potential profit of bone grafting. The chewing operation and loading on the mandible was simulated considering the three mandibular muscular forces including masseter, medial pterygoid, and temporalis. The result of FEM analysis of TI-wo-BG and TI-w-BG showed that in both models, screw number 6 endured a strain of 5684 and 2852[Formula: see text][Formula: see text]m/m which exceeded pathological and mild overload risk, respectively. This may increase the probability of screw loosening and system failure. The results proved the stability of the FFF and CP models. In addition, it can be concluded that stress and strain on the screw’s interfaces can decrease by improving the plate and increasing the friction at the interface of plate, bone and screw.

Low risk of iron overload or anaphylaxis during treatment of restless legs syndrome with intravenous iron: a consecutive case series in a regular clinical setting

ObjectiveTo evaluate the incidence of iron overload and anaphylaxis following intravenous (IV) iron treatment of restless legs syndrome (RLS). MethodsA total of 58 consecutive RLS patients, meeting clinical requirements for IV iron treatment according to current IRLSSG guidelines were recruited. IV iron treatment consisted of two 500 mg infusions of ferric carboxymaltose (FCM) administered five days apart. During each of the three follow-up visits we obtained blood samples, substantia nigra echogenity index (SNEI) by means of transcranial sonography (TCS), and assessed the severity of RLS symptoms (IRLS scale). “Iron overload risk” was defined as transferrin saturation (TSAT) > 45% on two consecutive follow-up visits. In patients who had a reduction in systemic iron levels following treatment, an additional 500 mg of FCM was administered when feasible. In such cases an additional two follow-up visits were performed. ResultsAmong the total sample, only 2/58 participants met criteria for iron overload risk. They had no evidence of liver damage and did not require additional treatment. Among the 21 patients receiving an additional 500 mg infusion after, only one patient was diagnosed with iron overload risk. Among these three patients, only one was a hemochromatosis gene carrier. No anaphylaxis or other side-effects were reported. ConclusionsIn real-life clinical conditions, the risk of iron overload is low when IV FCM is administered according to the safety limits defined in the current RLS treatment guidelines. However, a close clinical follow-up with periodic blood sampling for iron status, is needed.

Biomechanical Evaluation of Bone Quality Effect on Stresses at Bone-Implant Interface: A Finite Element Study

The aim of this study is to evaluate the effect of the alveolar bone quality on von Mises stress at the bone-implant interface during occlusal loading. Four (3D) finite element models of fully osteointegrated 3-mm diameter × 11.5-mm length dental implant indifferent alveolar bone with different cortical bone thickness are created, using SolidWorks computer aided design software. The alveolar bone cortical-spongy bone ratio modelled includes I) 90%-10%, II) 60%-40%, III) 40%-60%, and IV) 10%-90%. These models are then exported to ABAQUS software and stress analyses are run under an occlusal load of 70 N acting on the platform face of the dental implant. Results of this study show that the implants are subjected to similar stress distributions in all models; maximum stress values are confined in the outer cervical plate of the cortical bone around the neck. This could explain bone loss and implant de-osseointegration. Peak stresses are lowest in the model with 90% cortical bone (14.2 MPa) and almost doubled in the model with 10% cortical bone (26.6 MPa). The stress values gradually reduce towards the apical area, demonstrating masticatory force transfer from implant to bone. Furthermore, both cortical and spongy bone structures exhibit highest stress values in the model with thinnest cortical layer. The high interfacial stress concentration near the implant-cortical bone junction could lead to bone failure or implant instability induced by fatigue or overload risk. Results of our study could be a first step towards the development of a clinical pre-operative planning tool for dental implantolgy.