Output Measurements Research Articles

A Review of MRI Acoustic Noise Outputs and Hearing Protection Device Performance.

The acoustic noise outputs of MR equipment typically require a hearing protection device (HPD) to minimize the likelihood of patient hearing loss. Several different ways to quantify HPD performance have been developed and adopted over many years in different countries across the world (eg, NRR, SNR, SLC80). These HPD evaluations are done in controlled laboratory conditions, following different standardized methodologies, producing different performance ratings for the same HPD, and consequently of a variable relationship with achieved real-world usage performance assessments. Conversely, the MR manufacturers follow one standard (NEMA MS-4) which strives to produce a worst-case peak and average acoustic noise output measurement. Measuring the acoustic output of MR equipment is a complex undertaking in the confined patient space, especially when considering the variability of what is in the patient imaging space. Given both the MR equipment acoustic output measurements and the HPD performance rating, it is theoretically possible to estimate the worst-case patient exposure level, subject to the uncertainty of how successfully the protection was applied and population variability. An assessment, shown here, suggests that the worst-case outputs from the loudest MR equipment requires the best passive HPD performance presently available in order to meet patient protection guidelines, but only when the HPD is properly deployed. However, when considering government agency derating recommendations that estimate protection achieved during practical application, the various metrics are not consistent in confirming that the best HPD provide sufficient protection. This paper reviews the challenges of determining and providing sufficient hearing protection. The correct deployment of HPD, and its verification, is thus a critical factor in ensuring adequate patient protection and the main concern of this review. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 5.

Impaired maternal central hemodynamics precede the onset of vascular disorders of pregnancy at high altitude.

Hypertensive disorders of pregnancy represent an escalating global health concern with increasing incidence in low- to middle-income countries and high-income countries alike. The current lack of methods to detect the subclinical stages of preeclampsia (PE) and fetal growth restriction (FGR), two common vascular disorders of pregnancy, limits treatment options to minimize acute- and long-term adverse outcomes for both mother and child. To determine whether impaired maternal cardiovascular or uteroplacental vascular function precedes the onset of PE and/or FGR (PE-FGR), we used non-invasive techniques to obtain serial measurements of maternal cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), as well as uterine and fetal arterial resistance at gestational weeks 10-16, 20-24 and 30-34 for 79 maternal-infant pairs in La Paz-El Alto, Bolivia (3850 m), where the chronic hypoxia of high altitude increases the incidence of PE and FGR. Compared to controls (n=55), PE-FGR cases (n=24) had lower SV, higher SVR, and greater uterine artery resistance at 10-16 weeks. In addition, fetuses of women with lower SV and higher SVR at 10-16 weeks showed evidence of brain sparing at 30-34 weeks and had lower birth weights, respectively. While the trajectory of SV and SVR across pregnancy was similar between groups, PE-FGR cases had a comparatively blunted rise in CO from the first to the third visit. Impaired maternal central hemodynamics and increased uteroplacental resistance precede PE-FGR onset, highlighting the potential use of such measures for identifying high-risk pregnancies at high altitudes.

The Impact of Distributive Justice Perceptions on Alternative Work Arrangement Participation Intentions in Public Accounting

Turnover and staffing issues are consistently ranked among public accounting firms' most critical issues, but the post-COVID-19 work environment adds new and unique challenges. Now that employees have experienced remote work, many do not want to return to the office. However, if employees do not believe they can be successful using a flexible work arrangement at their current firm, they may go elsewhere. The need for successful flexible work programs is exacerbated by the declining interest in the accounting profession, which is increasing the accounting labor shortage and making competition for talent even greater. Accounting firms need to understand what factors impact an employee’s decision to participate in an alternative work arrangement (AWA). This study explores factors that impact AWA participation intentions using organizational justice perceptions. Using a sample of 135 public accountants, distributive justice perceptions surrounding AWAs were found to be positively related to AWA participation intentions. This finding extends the current AWA literature and provides valuable information to public accounting firms. This result informs firm leaders about the importance of equitable career outcomes when employees are considering AWAs. Firms can leverage this insight to ensure performance evaluation metrics focus on specific, measurable employee outputs, which should help ensure that work-related outcomes are consistent between employees regardless of their work arrangement.

Why Median Severity and Ordinal Scale Severity Values should not be used for Injury Burden Results: A Critical Review.

Injury burden is a composite measure of injury incidence and mean severity; this parameter has been reported as an output measure from injury surveillance studies in rugby for over 20 years. The benefits of reporting injury burden results have, more recently, been recognised in other sports. This wider use of injury burden as an output measure from injury surveillance studies has, however, highlighted misunderstandings about how to calculate, present and interpret injury burden data. The aim of this critical review is to explain why median severity and ordinal severity scales should not be used to calculate and report injury burden results in injury surveillance studies. Equations are presented to show how injury burden results should be calculated, and graphs and tables are presented to explain the errors that are introduced when median severity and ordinal scales of severity are used instead of mean severity. This critical review is intended to highlight the correct procedures for calculating, reporting and interpreting injury burden results in order to avoid incorrect results, conclusions and injury prevention recommendations being published.

Damage-Sensitive Feature for Long-Span Steel Box-Girder Suspension Bridges Under Service Loads Based on Long-Term Monitoring

To extract valuable data from long-term monitoring and identify structural damage to ensure the serviceability and safety of bridges, a commonly used method in large bridge maintenance. This article developed a time-domain energy-based method for identifying bridge damage based on long-term structural health monitoring noisy output measurements. This method first calculated an energy threshold within the structural frequency bandwidth of natural vibration at measurement points. Then, the structural damage was assessed by computing the time-domain energy accumulation. The improved procedure of this proposed method involved extracting modal frequencies from the signal for each modal order, determining the structural frequency bandwidth of natural vibration, and applying the square root envelope method to smooth vibration data and mitigate the impact of abnormal signals. Later, the applicability of the proposed method for damage identification was verified by comparing it with conventional modal flexibility and modal curvature methods. Finally, a case study on the Runyang bridge, a supported steel-box-girder suspension bridge with a main span of 1490 m in China, was made for demonstration. The results indicated that the area between 1/4-span and 1/2-span of the bridge was more sensitive to damage under service loads. The method performed well in identifying potential damage locations and assessing vulnerability. The calculation results using the method proposed in this article were consistent with those of traditional methods. The research offers methodological backing for utilizing extensive data monitoring in evaluating structural damage.

Observer Design for Fractional-Order Polynomial Fuzzy Systems Depending on a Parameter

For fractional-order systems, observer design is remarkable for the estimation of unavailable states from measurable outputs. In addition, the nonlinear dynamics and the presence of parameters that can vary over different operating conditions or time, such as load or temperature, increase the complexity of the observer design. In view of the aforementioned factors, this paper investigates the observer design problem for a class of Fractional-Order Polynomial Fuzzy Systems (FORPSs) depending on a parameter. The Caputo–Hadamard derivative is considered in this study. First, we prove the practical Mittag-Leffler stability, using the Lyapunov methods, for the general case of Caputo–Hadamard Fractional-Order Systems (CHFOSs) depending on a parameter. Secondly, based on this stability theory, we design an observer for the considered class of FORPSs. The state estimation error is ensured to be practically generalized Mittag-Leffler stable by solving Sum Of Squares (SOSs) conditions using the developed SOSTOOLS.

Computational hemodynamic indices to identify Transcatheter Aortic Valve Implantation degeneration

Background and Objectives:Structural Valve Deterioration (SVD) is the main limiting factor to the long-term durability of the bioprosthetic valves used for Transcatheter Aortic Valve Implantation (TAVI), a minimally invasive technique for the treatment of severe aortic stenosis. The aim of this retrospective study is to perform patient-specific computational analyses of blood dynamics shortly after TAVI to identify hemodynamic indices that correlate with a premature onset of SVD which is detected at 5-10 years long-term follow-up exam after TAVI. Methods:The study population comprises fourteen patients: seven cases with SVD at long-term follow-up were identified and seven cases without SVD were randomly extracted from the same cohort. Starting from pre-operative CT images, we created trustworthy post-TAVI scenarios by virtually inserting the bioprosthetic valve (stent and leaflets) and we qualitatively validated such virtual scenarios against post-TAVI CT scans, when available. We then performed numerical simulations imposing personalized inlet conditions based on patient-specific Echo Doppler cardiac output measurements and the numerical results were post-processed to identify suitable hemodynamics indices with the aim of discriminating between the SVD and non-SVD groups of patients. In particular, differences in terms of each individual index were evaluated using a Wilcoxon rank-sum test. Moreover, we defined three synthetic scores, based on suitably scaled hemodynamic indices of stress and vorticity, evaluated in different contexts: on the leaflets, in the ascending aorta, and in the whole domain. Results:We found that the hemodynamic index related to leaflets’ OSI individually shows statistically significant differences (p=0.007) between the SVD and non-SVD groups. Moreover, our proposed synthetic scores are able to clearly isolate the SVD group both in a two-dimensional space given by the aorta and leaflets scores and by only considering the global synthetic score. Conclusion:The results of this computational study suggest that blood dynamics may play an important role in creating the conditions that lead to SVD. Moreover, the proposed synthetic scores could provide further indications for clinicians in assessing and predicting TAVI valves’ long-term performance.

Flight tracking control of mini-drone: Flower pollination algorithm based model-free control

This paper presents a novel model-free control approach, Flower Pollination Algorithm-based Model-Free Control (FPA-MFC), for trajectory tracking of mini-drone quadrotor unmanned aerial vehicles (UAVs). The proposed approach employs an adaptive estimator based on filtered signals to approximate the nonlinear dynamic functions of the system. This approximator allows the development of a robust decentralized control law able to separately manage the position and attitude dynamics of the drone. The controller design is free of any prior knowledge of the system dynamics, and the control inputs are computed solely from instantaneous input and output measurements. Indeed, this can significantly reduce the computational burden and improve the efficiency of the control algorithm while preserving its simplicity. The design gains of the control law are selected using the metaheuristic flower pollination algorithm to achieve greater trajectory tracking performance and ensure closed-loop system stability. Simulation tests conducted on the Parrot mini drone platform validate the effectiveness and superior performance of FPA-MFC, compared to similar controllers without optimization and using the particle swarm optimization algorithm.

Abstract 4113405: The Role of Cardiac Power Output and Stroke Work Index in Balloon Pulmonary Angioplasty Therapy for Chronic Thromboembolic Pulmonary Hypertension

Background: Right ventricular (RV) and left ventricular (LV) measures of cardiac power output (CPO) and stroke work index (SWI) are existing markers of cardiac function and clinical outcomes. These metrics have not been used to evaluate the effects of balloon pulmonary angioplasty (BPA) therapy in patients with chronic thromboembolic pulmonary hypertension (CTEPH). Methods: CTEPH patients who underwent at least six BPA sessions and were included in the UC San Diego BPA registry were included for analysis. Left and right ventricular CPO and SWI during each session were recorded. Cardiac output was measured using the thermodilution technique. Differences in continuous variable measurements before versus after BPA therapy were evaluated using the Student T-test. P-value <0.05 was significant. Results: A total of 66 subjects underwent six consecutive BPA sessions (55.5% female, BMI 28.3±6.10kg/m 2 ,16.7% prior pulmonary thromboendarterectomy surgery) and were included for analysis. Measurements of RV function, including RVCPO (Pre-BPA 0.38±0.14 vs Post-BPA 0.30±0.13 W, p=0.001)(Figure 1) and RVSWI (Pre-BPA 16.52±5.09 vs Post-BPA 14.14±4.00 g*m/beat/m 2 , p=0.004) significantly decreased after BPA therapy. Measurements of LV function, including LVCPO (Pre-BPA 1.00±0.32 vs Post-BPA 1.04±0.31 W, p=0.523) (Figure 2) and LVSWI (Pre-BPA 37.13±10.14 vs Post-BPA 39.73±9.37 g*m/beat/m 2 , p=0.152) did not change significantly after BPA therapy. The ratio of LVCPO/RVCPO increased in stepwise fashion from baseline to the last BPA session (2.82± 0.95 vs. 3.54±1.31 W, p<0.001)(Figure 3). Conclusions: Hemodynamic work expended by the RV decreased after BPA therapy, while work expended by the LV remained unchanged during BPA therapy. The ratio of LV-to-RV work increased in a stepwise manner during consecutive BPA sessions. These measurements may be useful parameters to monitor clinical response to BPA therapy.

Updated 5-Year Institutional Bibliometric Profiles for United States Neurosurgery Residency Programs and the Relationship Between Social Media Presence and Objective Departmental Metrics.

The authors report current 3-year and 5-year institutional bibliometric profiles and investigate the correlations between objective metrics of neurosurgical residency programs and social media presence, including residency program size, faculty count, Doximity rankings, and measures of research output. A list of neurosurgery residency programs was obtained through the Doximity Residency Navigator. Publication history of faculty members was compiled using Scopus and analyzed to create institutional bibliometric profiles from 2018-2022 to 2020-2022. Mann-Whitney U tests were used to compare departmental metrics for institutions with and without social media accounts. Spearman rank correlations were used to examine the relationship between social media following and metrics, and between Twitter following and methods of Twitter use. 74% (n = 86) of neurosurgery programs have a Twitter account, 47% (n = 55) have a Facebook account, 63% (n = 73) have Instagram accounts, and 16% (n = 19) have LinkedIn accounts. The most notable differences were found when comparing departments with and without Twitter accounts, where a difference was found in all metrics except the average H-index. Residency program size, faculty count, average H-index, 3-year and 5-year publication and citation counts per faculty, and institutional H-indices were significantly correlated with Twitter following. Higher Doximity rankings were correlated with Twitter following and Facebook likes. There is a greater increase in 5-year citations per publication from 2009-2013 to 2018-2022 for institutions that created departmental Twitter accounts after 2013. Articles that were tweeted about had higher 3-year citations per publication than the institution's overall 3-year citations per publication. Our findings provide updated insight into the relationship between social media presence and objective academic metrics of neurosurgery departments. We identify and quantify correlations between social media platforms and program characteristics, with a focus on research output. These metrics can be used to guide programs in their development of social media.

Minimizing Acute Kidney Injury in Pediatric Cardiac Surgery: Incidence, Early Detection, and Preemptive Measures.

Background Acute kidney injury (AKI) poses a significant challenge in pediatric cardiac surgery, having a profound impact on patient morbidity and mortality. This study aims to determine the incidence of AKI, explore novel biomarkers for early detection,assess potential risk factors along with preemptive strategies to minimize its incidence and compare the results with similar studies that did not use these interventions. Methods This prospective observational cohort study, conducted from October 2022 to June 2024 at a tertiary care center, involved 44 pediatric patients, aged three months to 15 years, undergoing cardiac surgery. Kidney function was assessed through preoperative and postoperative measurements of serum creatinine, urine output, blood urea, and newer biomarkers such as cystatin C and urine neutrophil gelatinase-associated lipocalin (NGAL). AKI was defined and classified using the Acute Kidney Injury Network (AKIN) criteria, based on increases in serum creatinine or reductions in urine output within the first three days post surgery. To reduce the risk of AKI, a low-dose vasopressin infusion and blood transfusion were administered to maintain renal perfusion and optimal hematocrit levels. The incidence of AKI was calculated and compared with other studies that did not utilize these strategies Results AKI occurred in 31.8% (n=14) of the pediatric patients undergoing cardiac surgery. To reduce the risk of AKI, preemptive low-dose vasopressin was used as a preventive strategy. Patients who developed AKI exhibited significant elevations in serum creatinine, blood urea, and cystatin C, with postoperative NGAL levels exceeding 50 ng/ml. The study found a strong correlation between lower intraoperative hematocrit levels (<30%) and a higher incidence of AKI (100% vs. 6.2%, p<0.001). Conclusions Effective management of intraoperative hematocrit levels and the preemptive use of vasopressin are promising strategies for reducing AKI risk by optimizing renal perfusion and function during cardiac surgery.Early detection through biomarkers like cystatin C and NGAL offers the potential for timely intervention and better patient outcomes. These findings contribute to improving risk assessment and perioperative management in pediatric patients vulnerable to AKI.

Unscented-Kalman-Filter-Based Remote State Estimation for Complex Networks With Quantized Measurements and Amplify-and-Forward Relays.

In this article, the remote estimation problem is addressed for a class of discrete-time complex networks under the influence of probabilistic quantization and amplify-and-forward (AF) relays. The underlying complex network model, which is inherently nonlinear and stochastic, is affected by additive process and measurement noises. Owing to the limited bandwidth of the transmission channel, the measurement outputs are quantized by a probabilistic quantizer prior to transmission. To enhance the signal quality over long-distance transmissions, the quantized measurements are sent to AF relays and subsequently forwarded to the estimator. Utilizing the unscented Kalman filter approach, a novel state estimator is designed to minimize an upper bound on the estimation error covariance. Moreover, sufficient conditions are derived to ensure that the estimation error is exponentially bounded in the mean-square sense. Lastly, the efficacy of the proposed scheme is illustrated through numerical simulations.

Thermal characterization of Xenon-Arc flash lamp heating system for automated fiber placement (AFP) of thermoplastic composites

In this study, a systematic experimental and simulations-based characterization of key thermal aspects of the arc-flash lamp based AFP heating is presented. Ex-situ measurements of heat flux output from the flash lamp as well as the resulting temperature field on a material sample are carried out in a geometry representative of actual manufacturing conditions, using a heat flux sensor and infrared thermography. A thermal simulation model is developed to predict the temperature field resulting from the measured heat flux data. Good agreement is found between experimental data and simulation predictions. This work contributes towards developing a fundamental understanding of heat transfer processes during AFP manufacturing. Data presented here may be of broad benefit to AFP-related research, and may contribute towards process design and optimization in order to further expand the capabilities of this promising additive manufacturing technology.

Polynomial fitting calibration method for K-type thermo-couples based on the least squares method

Abstract Thin-film thermocouples, a crucial technology for accurate temperature measurement, have attracted considerable attention in energy utilization, environmental monitoring, and advanced manufacturing. This paper provides an overview of the evolution of thin-film thermocouples, with a focus on the calibration methods and experimental performance of K-type thermocouples. Utilizing a five-layer film structure that includes a polyimide substrate, aluminum oxide insulation layer, nickel-chromium and nickel-silicon metal films, and a silicon oxide protective layer, we have designed and implemented a new thin-film thermocouple temperature measurement system, which has been experimentally validated for stability and repeatability under high-temperature conditions. The results indicate that the system demonstrates excellent thermoelectric potential output and good repeatability in temperature measurement within the range of 50°C to 250°C. Although the long-term stability in extremely high-temperature environments requires further study, this research provides theoretical and experimental support for the future development of thin-film thermocouple technology.

Model-free distributed state estimation with local measurements.

In this paper, the state estimation problem of physical plants with unknown system dynamic is revisited from the perspective of limited output information measurement, which corresponds to those with characteristics of high-dimensional, wide-area coverage and scatter. Given this fact, a network of sensors are used to carry out the measurement with each one accessing only partial outputs of the targeted systems and a novel model-free state estimation approach, named distributed stochastic variational inference state estimation, is proposed. The key idea of this method is to compensate for the impacts of local output measurements by adding nearest-neighbor rule-based information interaction among estimators to complete the state estimation. It finds from the numerical experiments that the proposed method has clear advantages in both estimation accuracy and speed, and it also provides guidance on how to improve the efficiency of state estimation under local measurements.

New Predictor‐Based Anti‐Disturbance Control for Discrete‐Time Systems With Input Delay Subject to Time‐Varying Uncertainties

ABSTRACTIn this article, a new predictor‐based anti‐disturbance control scheme is proposed for discrete‐time systems with input delay subject to time‐varying uncertainties, by only using the system output measurement. A high‐order extended state observer is firstly constructed to simultaneously estimate the system state, unknown disturbance and its high‐order difference with specification. Two alternative designs of the system state and disturbance predictors are then presented to construct an advanced anti‐disturbance control scheme. The disturbance attenuation performance of the resulting closed‐loop system is quantitatively analyzed. Moreover, a matrix‐inequality‐based sufficient condition is established to evaluate robust stability of the closed‐loop system under time‐varying uncertainties. Finally, a benchmark example is adopted to demonstrate the effectiveness and advantages of the proposed control schemes over the existing methods.

Comparison between invasive cardiac output and left ventricular assist device flow parameter.

To evaluate the correlation between left ventricular assist device flow parameter and invasive cardiac output measurements. We retrospectively evaluated right heart catheterization examinations performed in left ventricular assist device patients from 2 tertiary medical centres. We evaluated the correlation between cardiac output measurement methods (indirect Fick and thermodilution) and pump flow parameter using linear regression, and the agreement was graphically displayed using Bland-Altman plot technique. Clinical, echocardiographic, pump and haemodynamic parameters were compared between patients with and without discordance, defined as at least a 20% difference between measurements. The study population consisted of 102 patients [median age 58 (51-64), 86% males, 17 ± 12 months post left ventricular assist device implantation] with a total of 544 measurements compared. Discordance between measurements was present in 102 of 226 (45%) comparisons between indirect Fick and pump flow and in 72 of 161 (48%) between thermodilution and pump flow. A comparison of indirect Fick and left ventricular assist device exhibited a statistical correlation of R = 0.751, and that of thermodilution and left ventricular assist device of R = 0.789. Parameters associated with the presence of discordance between cardiac output measurements included a higher rate of aortic valve opening, lower indirect Fick and higher thermodilution cardiac output. After excluding the lowest tertile of indirect Fick cardiac output values, the correlation between measurements improved (thermodilution: R = 0.879 and indirect Fick: R = 0.843, P < 0.001). The current left ventricular assist device flow parameter provides an estimation of cardiac output that correlates well with indirect Fick and exhibits the strongest correlation with thermodilution. This correlation was stronger after excluding lower cardiac output values.

H∞ Filtering of Mean Field Stochastic Differential Systems

This paper addresses the H∞ filtering problem for mean field stochastic differential systems that involve both state-dependent and disturbance-dependent noise. We assume that the state as well as the measurement output is distracted by an uncertain exogenous disturbance. Firstly, a sufficient condition for the stochastic-bounded real lemma is given. Next, H∞ filtering, which is built upon a stochastic-bounded real lemma, is put forward by two linear matrix inequalities. Furthermore, the validation of the theoretical analysis is demonstrated with two examples.

Research on Highly Reliable Self-Powered Vibration Sensors for Geological Drilling

Vibration signals at the bottom of the drill string during geological drilling are crucial for lithological identification and drilling parameter optimization. However, existing downhole vibration sensors suffer from limitations in power supply and reliability. This study proposes a self-powered vibration sensor with high redundancy based on the triboelectric nanogenerator principle, which is capable of measuring both axial and transverse vibrations, thereby reducing the dependence on external power sources. The experimental results show that the sensor can measure axial vibration frequencies ranging from 0 to 11 Hz with an error of less than 4% and transverse vibration frequencies ranging from 0 to 5 Hz with an error of less than 5%. It can operate stably in temperatures from 0 to 180 °C and relative humidities from 0 to 95%. The sensor’s axial vibration measurement features six identical measurement structures, providing high redundancy and effectively enhancing its reliability. Furthermore, the sensor exhibits power generation capabilities. When an external load of 1 MΩ is applied to the axial measurement module and 10 MΩ to the transverse measurement module, the sensor achieves its maximum power output for both axial and transverse measurements, reaching 32.4 × 10−9 W and 2.1 × 10−9 W, respectively. Compared to traditional bottom-of-the-hole vibration sensors, this sensor possesses self-powering capabilities and high reliability, which can improve the operational efficiency and hold significant practical value for future applications.

Haemodynamic monitoring after paediatric cardiac surgery using echocardiography and PiCCO.

Haemodynamic instability is common after surgical repair of CHDs in infants and children. Monitoring cardiac output in addition to traditional circulation parameters could improve the postoperative care of these patients. Echocardiography and transpulmonary thermodilution are the two most common methods for measuring cardiac output in infants. To compare the results of cardiac output measurements using echocardiography and a transpulmonary thermodilution setup after paediatric cardiac surgery. Forty children, scheduled for elective repair of a ventricular septal defect or of an atrio-ventricular septal defect using cardiopulmonary bypass, were enrolled in this prospective, observational study. Cardiac output was simultaneously measured using echocardiography and a commercially available transpulmonary thermodilution method (PiCCO™) at 18 h after the end of surgery. At 18 h after surgery, PiCCO™ gave a mean of 3.0% higher cardiac output than echocardiography. This difference was not statistically significant. 95% of the observations fell within -50.0 to 82.6%. The methods were found to have a good agreement on average, with no statistically significant difference between them. However, the spread of the results was large. It is questionable whether the methods can be used interchangeably in clinical practice.