Output Measurements Research Articles

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.

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.

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.

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.

Small changes in the transducer position cause a systematic change in cardiac output readings: implications for clinical practice.

To systematically evaluate the effect of small changes in transducer position on key hemodynamic variables including CO generated by 4th generation FloTrac software. After cardiac surgery, cardiac output, mean arterial pressure, systemic vascular resistance, and stroke volume variation were measured with 4 generation Flotrac software. The transducer position was randomly placed at the midaxillary plane, 4cm higher than the midaxillary plane or 4cm lower than the midaxillary plane. Averages of three measurements were used. Data was available from 20 patients. Cardiac output increased from 4.59L/min (± 0.92) to 4.78L/min (± 0.99) with the transducer position at the midaxillary plane to 4cm higher than the midaxillary plane, and cardiac output decreased to 4.43L/min (± 0.90) with the transducer 4cm lower than midaxillary plane (P < 0.001). On the relative scale, CO increased 4.1% (95% CI 3.1-5.0) when comparing the higher transducer level with the midaxillary plane position, and CO decreased 3.4% (95% CI 2.4-4.4) when comparing the midaxillary plane position with the lower transducer level, correspondiong to changes in CO of ≈ 1% per 1cm change in transducer position. Mean arterial pressure and systemic vascular resistance both changed significantly with transducer position (both P < 0.001), whereas no statistically or clinically significant effect was seen on stroke volume variation (P = 0.98). A four-centimeter change in vertical transducer position induced clinically significant changes in cardiac output measurements by 4th generation FloTrac software. Definitions of optimal cardiac output in goal-directed therapy algorithms require meticulous transducer adjustment and can only be used in the reference patient position.

Bedside imaging

Sonography, in particular echocardiography, is essential in the assessment of volume status and hemodynamics in critically ill patients. Examination of the left ventricle, in addition to assessing ventricular function, provides valuable information, including the "kissing papillary muscle sign," which may indicate fluid responsiveness. Examination of the right ventricle is also important because it is sensitive to both volume and pressure overload. Assessment of diastolic function and measurement of inferior vena cava width and variability provide clues to left and right ventricular preload, respectively. Measurement of stroke volume and cardiac output allows further assessment of hemodynamics and also permits determination of stroke volume variability.

Biomechanics of the Human Knee Joint in Maximum Voluntary Isometric Flexion: Study of Changes in Applied Moment, Agonist-Antagonist Participations, Joint Center, and Flexion Angle.

Estimation of the knee joint strength by maximum voluntary isometric contraction (MVIC) is a common practice to assess strength, coordination, safety to return to work or engage in sports after an injury, and to evaluate the efficacy of treatment modalities and rehabilitation strategies. In this study, we utilize a previously validated coupled finite element-musculoskeletal model of the lower extremity to explore the sensitivity of output measures (posterior cruciate ligament [PCL]/muscle/contact forces and passive moments) in knee MVIC flexion exercises at seated position. To do so, at three knee flexion angles (KFA), input measures (resistance moment and contribution moments of quadriceps and gastrocnemii) were varied at four levels each using the Taguchi design of experiment. Our findings reveal significant increases in PCL forces with KFA (p < 0.01), net MVIC moment (p < 0.01), and resistance moment of quadriceps (p < 0.01). In contrast, they drop at larger activity in gastrocnemii (p < 0.01). Tibiofemoral (TF) contact forces increase with the net MVIC moment (p < 0.01). The passive knee flexion moment, while highly dependent on the location at which computed, also increases with the net MVIC moment (p < 0.01). Changes in KFA, MVIC moment, and proportions thereof carried by quadriceps and/or gastrocnemii substantially affect biomechanics of the joint. Compared with level walking and stair ascent, slightly larger contact forces/stresses and much greater PCL forces are computed. This study improves our understanding of the knee joint behavior during MVIC in effective evaluation and rehabilitation interventions. Besides, it emphasizes the importance of positioning the joint center in model studies.

Distributed adaptive secure consensus control for multiagent systems under denial-of-service attacks

This paper investigates the security consensus of multiagent systems (MASs) under denial-of-service (DoS) attacks. First, we introduce a novel dynamic consensus protocol against DoS attacks by utilising relative measurement outputs. Then, based on the edge pinning technique, the novel distributed synchronous adaptive laws are designed to tune a small fraction of coupling strengths between neighbouring agents, under which all updating of coupling strengths will stop when DoS attacks are activated. To extend the application of secure dynamic edge pinning consensus scheme, we further develop the distributed asynchronous adaptive laws, under which only the coupling strengths of the attacked edges stop updating rather than all coupling strengths when DoS attacks are activated. Note that the proposed secure dynamic edge pinning consensus protocols with distributed synchronous and asynchronous adaptive laws are fully distributed and operate independently of any global information. At last, we validate the validity of the proposed distributed adaptive secure dynamic consensus schemes via an example.

Strategies for crowdsourcing hearing health information: a comparative study of educational programs and volunteer-based campaigns on Wikimedia

BackgroundSeveral health institutions developed strategies to improve health content on Wikimedia platforms given their unparalleled reach. The objective of this study was to compare an online volunteer-based Wikimedia outreach campaign with university course Wikipedia assignments (both focused on improving hearing health content in Wikimedia’s public digital knowledge archives), in terms of the reach of the contributions and the extent of the participants’ input. A secondary objective was to examine the feasibility and the implementation of the different strategies.MethodsThe research team partnered for the (1) coordination of improvements in hearing and healthcare content through educational programs using Wikimedia platforms, (2) participation in the global campaign Wiki4WorldHearingDay2023 and (3) evaluation of the proposed strategies. Metrics used in the comparison of the two strategies included the number of articles edited, number of views of the edited articles (as reach) and the extent of edits, captured as the number of words. The feasibility evaluation included assessing recruitment success and the implementation of the proposed plan among faculty, students from various university programs, and volunteers representing different constituencies.ResultsThe effort increased the availability of quality plain language information on hearing conditions and hearing care. Both strategies demonstrated to be feasible by their success in recruiting participants who contributed to the effort and by measurable outputs as edits. The contribution of content to Wikimedia platforms as part of education activities provided a more robust result. Wiki4WorldHearingDay2023 145 participants (78 from educational programs) contributed 167,000 words, 258 + references and 140 images to 322 Wikipedia articles (283 existing and 39 new ones), which were viewed 16.5 million times. Contributions occurred in six languages. Edits in Portuguese, mainly by those involved in educational programs, led the number of articles (226 or 70.2%) that were expanded or created during the 5-month tracking period.ConclusionsThe elements that contributed to the success of the studied strategies include an impact topic, coordination with educational programs, international multidisciplinary collaborations, the dissemination of the initiative in several platforms, connection with a robust local Wikimedia affiliate, and the use of a technical infrastructure that provides metrics and coordination mechanisms.Graphical abstract

Analysis of the Level of Agricultural Development in Kazakhstan: Identifying Agro-Hubs

The study examines Kazakhstan's agricultural sector and its potential for developing resilient agro-hubs, focusing on identifying regions that can contribute to the country's long-term agricultural growth. The purpose of this study is to examine essential agricultural indicators, including gross agrarian output, gross crop production, gross livestock production, and agricultural services, in order to identify regions with the potential for agro-hub development. The methodology includes Pearson correlation analysis of data collected from national agricultural reports and regional statistical databases. Data for the study were gathered from national agricultural reports and regional statistical databases, which provide quantitative measures of agricultural output, crop yields, livestock production, and farming services. Results indicate the strongest correlations between Kostanay and North Kazakhstan (0.995 for Gross Agricultural Output and 0.996 for Crop Production, p &lt; 0.001). Additionally, significant alignment in crop production was observed between Almaty and South Kazakhstan (0.969, p = 0.007), whereas weaknesses in agricultural services were noted, particularly in Kyzylorda and Zhambyl, with a negative correlation. The results highlight the northern and southern regions' potential for forming agro-hubs supported by solid production indicators. The study provides strategic recommendations for policymakers to foster regional collaboration, enhance productivity, and promote sustainable agricultural development across Kazakhstan. Future research will focus on improving infrastructure and developing collaborative agricultural initiatives within agro-hubs to strengthen Kazakhstan's agricultural sector resilience.

The effect of caffeine chewing gum on muscle performance and fatigue after severe-intensity exercise: isometric vs. dynamic assessments in trained cyclists.

This study investigated the effect of caffeinated chewing gum (GUMCAF) on muscle fatigue (isometric vs. dynamic) after severe-intensity cycling bouts. Fifteen trained male cyclists participated in four visits. Each visit involved two severe-intensity cycling bouts (Δ1 and Δ2) lasting 6min, separated by a 5-min recovery period. Muscle fatigue was assessed by isometric maximal voluntary knee extension contraction (IMVC) with twitch interpolation technique and dynamically by 7s all-out cycling sprints. Assessments were performed before GUMCAF (Pre-GUM) and after the cycling bouts (Post-Exercise). GUMCAF and placebo gum (GUMPLA) were administered in a randomized double-blind procedure with participants receiving each gum type (GUMCAF and GUMPLA) during two separate visits. The results showed no significant interaction between gum types and time for the isometric and dynamic measurements (p > 0.05). The percentage change in performance from Pre-GUM to Post-Exercise showed no significant difference between GUMCAF and GUMPLA for either the dynamic-derived TMAX (~ -17.8% and -15.1%, respectively; p = 0.551) or isometric IMVC (~ -12.3% and -17.7%, respectively; p = 0.091) measurements. Moderate to large correlations (r = 0.31-0.51) were found between changes in sprint maximal torque and maximal power output measurements and isometric force, for both gum conditions. GUMCAF was not effective in attenuating muscle force decline triggered by severe-intensity cycling exercises, as measured by both isometric and dynamic methods. The correlations between IMVC and cycling maximal torque and power output suggest caution when interpreting isometric force as a direct measure of fatigue during dynamic cycling exercises.

Low peaking-phenomenon cascade high-gain observer design with LPV/LMI method.

To cope with the well-known peaking phenomenon and noise sensitivity in the application of the High-Gain observer, a parameter tuning method based on the LPV/LMI approach for a 2nd-order cascade observer structure is proposed in this paper. Compared to other high-gain observer methods, this method can significantly reduce the infimum of gain in the observer, thereby reducing the peak phenomenon of state estimation and the influence of measurement output noise. By transforming the observer structure into a Luenberger-like structure, the parameters of the observer can be solved by one linear matrix inequality (LMI) with a high-gain effect or a 2n of LMI sets (LMIs) without a high-gain effect. Then by decomposing the nonlinear part of the system dynamics into high-dimensional and low-dimensional parts, we could solve the adjustable number [Formula: see text] of LMIs can be solved to obtain the result with limited high-gain effect. Stability analysis based on the Lyapunov method proves the convergence of this method, and the effectiveness of this method is verified through applications to one single-link mechanical arm model and a vehicle trajectory estimation application.