Output Measurements Research Articles

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.

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 centers. We evaluated the correlation between cardiac output measurement methods (indirect Fick and thermodilution) and pump flow parameter using linear regression, 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 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 measurement compared. Discordance between measurements were 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.

Energy Transition to Green Energy Sources – Role of Socioeconomic Disparities and Administrative Policies

This study establishes the policy structure needed for achieving an energy transition in accordance with the goals of the COP26 Summit, taking into consideration disparities in socioeconomic status and the efficacy of regulations. We suggest a newly created energy transition index. It is a hypothesis-based output measure that employs the energy steps. By including (a) the shift to a green energy source and (b) the shift to more effective sources, the index makes it possible to understand the energy transition possibility in all countries. We examine the dynamic and absolute marginal consequences of energy transition factors on parameter estimations by applying the two-step System GMM method and data from 37 OECD countries between 2001 and 2022. The findings demonstrate that energy transition factors have less of an effect due to economic and social inequalities, but effective governance can increase those effects. Consistent with a scenario-based policy-development methodology, the results contribute significantly to the advancement of prospective policy discussions. Focusing on the completion of SDGs 7 and 13 they have significant real-world consequences for the creation of the SDG-oriented policy structure.

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.

Distributed Observer for Linear Systems with Multirate Sampled Outputs Involving Multiple Delays

This paper focuses on the design of a continuous distributed observer for linear systems under multirate sampled output measurements involving multiple delays. It is mathematically proved that the continuous distributed observer can achieve estimation in a sensor network environment, where output measurements from each sensor are available at different sampling instants, whether these times are periodic or aperiodic, and despite the presence of multiple time-varying delays. Each sampled and delayed measurement represents a node of the network, necessitating a dedicated observer for each node, which has access to only part of the system’s output and communicates with its neighbors according to a given network graph. The exponential convergence of the error dynamics is ensured by Lyapunov stability analysis, which accounts for the influence of the sampled and delayed measurements at each node. To demonstrate the effectiveness of the proposed observer, simulation tests were conducted on the tracking control of chasing satellites in low Earth orbit (LEO), encompassing both small and large sampling rates and delays. The continuous distributed observer with sampled output measurements exhibited convergence in scenarios with different sampling intervals, even in the presence of time-varying delays, achieving asymptotic omniscience, as demonstrated in the convergence analysis.

Development of a Polymicrobial Colony Biofilm Model to Test Antimicrobials in Cystic Fibrosis.

A range of bacteria biofilm models exist for the testing of antibiotics. However, many of these are limited to a single experimental output, such as colony-forming units or metabolic activity. Furthermore, many biofilm models do not reflect the biological and physiochemical properties of the human host environment. This is an important issue in many conditions, but most noticeably in cystic fibrosis (CF). A large proportion of people with CF suffer from both chronic and intermittent infections, and in vitro, antibiotic susceptibility testing poorly correlates with patient treatment outcomes. Some biofilm models incorporate CF lung-relevant media, including synthetic sputum mimics, but do not consider the polymicrobial nature of the environment, which alters biofilm architecture, physiology, and the way microbes respond to treatment. The solid-air interface colony biofilm model described here is highly adaptable and incorporates both CF-relevant media and a polymicrobial context. This model can also be used for mid-throughput screening of antimicrobials and to study their effect on polymicrobial dynamics. Output measurements from the model can be colony-forming units, metabolic activity, and confocal microscopy analysis. The model can easily be adapted to different microorganisms, media, temperatures, and variable oxygen conditions and can be used to test a wide range of chemical, biological, and physical treatments.

Which ERP components are effective in measuring cognitive load in multimedia learning? A meta-analysis based on relevant studies.

The open and generative nature of multimedia learning environments tends to cause cognitive overload in learners, and cognitive load is difficult for researchers to observe objectively because of its implicit and complex nature. Event-related potentials (ERP), a method of studying potential changes associated with specific events or stimuli by recording the electroencephalogram (EEG), has become an important method of measuring cognitive load in cognitive psychology. Although many studies have relied on ERP output measurements to compare different levels of cognitive load in multimedia learning, the results of the effect of cognitive load on ERP have been inconsistent. In this study, we used a meta-analysis of evidence-based research to quantitatively analyze 17 experimental studies to quantitatively evaluate which ERP component (amplitude) is most sensitive to cognitive load. Forty five effect sizes from 26 studies involving 360 participants were calculated. (1) The results of the studies analyzed in subgroups indicated high level effect sizes for P300 and P200 (2) Analyses of moderating variables for signal acquisition did not find that different methods of signal acquisition had a significant effect on the measurement of cognitive load (3) Analyses of moderating variables for task design found that a task system with feedback was more convenient for the measurement of cognitive load, and that designing for 3 levels of cognitive load was more convenient for the measurement of cognitive load than for 2 levels of cognitive load. (4) Analyses of continuous moderating variables for subject characteristics did not find significant effects of age, gender, or sample size on the results.

Correlation between corrected carotid flow time and left ventricular outflow tract velocity-time integral using a novel technique.

Transthoracic echocardiography (TTE) is widely used for assessing patients in the intensive care unit, with cardiac output measurement being crucial for hemodynamic monitoring. This is achieved by measuring the velocity-time integral (VTI) of the left ventricular outflow tract (LVOT), which serves as a surrogate of stroke volume. However, conducting TTE in the critical care setting presents several challenges. Our primary objective was to investigate the relationship between carotid corrected flow time (cCFT) and LVOT VTI. Additionally, we aimed to determine the threshold cCFT value that reliably predicts a normal LVOT VTI. This proof-of-concept study involves a post-hoc analysis from a diagnostic accuracy investigation conducted in a medical-surgical intensive care unit. We included patients admitted to the ICU from December 2021 to January 2022. We used a phased array transducer to measure the cCFT at the left supraclavicular fossa and the LVOT VTI in an apical 5-chamber view. We included 22 patients. The Spearman coefficient between LVOT VTI and cCFT was 0.82 (p < 0.0001). The area under the ROC curve for cCFT to predict LVOT VTI equal to or greater than 17 cm was 0.871 (95% CI 0.660-0.974). A cCFT exceeding 283 ms predicted LVOT VTI equal to or greater than 17 cm with a sensitivity of 93.3% (95% CI 68.1% to 99.8%) and specificity of 85.7% (95% CI 42.1% to 99.6%). The cCFT, measured using a novel technique with a phased array transducer, shows a strong correlation with LVOT VTI. Additionally, cCFT predicts a normal LVOT VTI with good sensitivity and specificity in critically ill patients. Larger studies are warranted to validate these findings.

The Brand Premium

Abstract We highlight the limitations of using cumulative advertising expenses as an input measure of brand value. Using two output measures—Interbrand’s data and a novel text-based measure—we find that an equal-weighted portfolio of top brands yields an annual abnormal return of 3%. The excess returns are driven by companies that develop their brands internally. Intangible factors proposed in the literature have no explanatory power for the premium. Analysts underestimate the future earnings of top brands, leading to significant excess returns following earnings announcements. We find no abnormal returns associated with the input measure of brand value. (JEL G4, G12, G14, M41)

ViCE: An automated and quantitative program to assess intestinal tissue morphology

Background and objectiveThe tissue morphology of the intestinal surface is architecturally complex with finger-like projections called villi, and glandular structures called crypts. The ratio of villus height-to-crypt depth ratio (Vh:Cd) is used to quantitatively assess disease severity and response to therapy for intestinal enteropathies, such as celiac disease and is currently quantified manually. Given the time required, manual Vh:Cd measurements have largely been limited to clinical trials and are not used widely in clinical practice. We developed ViCE (Villus Crypt Evaluator), a user-friendly software that automatically quantifies histological parameters in standard hematoxylin and eosin-stained intestinal biopsies. MethodsViCE is based on mathematical morphology operations and is scale and staining agnostic. It evaluates tissue orientation, identifies geometrical structure, and outputs key tissue measurements. ResultsThe output measurements of Vh:Cd are concordant with manual quantifications across multiple datasets. ConclusionsThe underlying mathematical morphological approach for ViCE is robust, and reproducible and easily adaptable for measurement of morphological features in other tissues.