Stability in Time-Delay Systems: Quiet Standing Case Study

The analysis of linear time-delay systems has attracted much interest in the literature over last five decade. Two types of stability conditions, namely delay-independent which results guarantee stability for arbitrarily large delays and delay-dependent, results take into account the maximum delay that can be tolerated by the system and, thus, are more useful in applications. The stability in general for linear time-delay systems, can be checked exactly only by eigenvalue considerations. When reasonable chosen with intentional delays, case study effects on time-delay of ankle torque on the stability of quiet standing, it can be used to stabilize and improve the close-loop response of these systems

Stability in Time-Delay Systems: Quiet Standing Case Study

The analysis of linear time-delay systems has attracted much interest in the literature over last five decade. Two types of stability conditions, namely delay-independent which results guarantee stability for arbitrarily large delays and delay-dependent, results take into account the maximum delay that can be tolerated by the system and, thus, are more useful in applications. The stability in general for linear time-delay systems, can be checked exactly only by eigenvalue considerations. When reasonable chosen with intentional delays, case study effects on time-delay of ankle torque on the stability of quiet standing, it can be used to stabilize and improve the close-loop response of these systems

Improvement of Pitch Motion Control of an Aircraft Systems

The movement of the aircraft pitch is very important to ensure the passengers and crews are in intrinsically safe and the aircraft achieves its maximum stability.The objective of this study is to provide a solution to the control system that features particularly on the pitch angle motion of aircraft systemin order to have a comfort boarding. Three controllers were developed in these projects which wereproportional integral derivative (PID), fuzzy logic controller (FLC), and linear quadratic regulator (LQR) controllers. These controllers will help improving the pitch angle and achievingthe target reference. By improving the pitch motion angle, the flight will be stabilized and in steady cruise (no jerking effect), hence provides all the passengers withthe comfort zone. Simulation results have been done and analyzed using Matlab software. The simulation results demonstrated LQR and FLC were better than PID in the pitch motion system due to the small error performance. In addition, withstrong external disturbances, a single controller is unable to control the system, thus, the combination of PID and LQR managed to stabilize the aircraft

Prediction of the remnant liver hypertrophy ratio after preoperative portal vein embolization.

Background: Portal vein embolization (PVE) is considered to improve the safety of major hepatectomy. Various conditions might affect remnant liver hypertrophy after PVE. The aim of the present study was to clarify the factors that affect remnant liver hypertrophy and to establish a prediction formula for the hypertrophy ratio. Methods: Fifty-nine patients who underwent preoperative PVE for cholangiocarcinoma (39 patients), metastatic carcinoma (10 patients), hepatocellular carcinoma (8 patients), and other diseases (2 patients) were enrolled in this study. For the prediction of the hypertrophy ratio, a formula with stepwise multiple regression analysis was set up. The following parameters were used: age, gender, future liver remnant ratio to total liver (FLR%), plasma disappearance rate of indocyanine green (ICGK), platelet count, prothrombin activity, serum albumin, serum total bilirubin at the time of PVE and the maximum value before PVE (Max Bil), as well as a history of cholangitis, diabetes mellitus, and chemotherapy. Results: The mean hypertrophy ratio was 28.8%. The 5 parameters detected as predictive factors were age (p = 0.015), FLR% (p < 0.001), ICGK (p = 0.112), Max Bil (p < 0.001), and history of chemotherapy (p = 0.007). The following prediction formula was established: 101.6 - 0.78 × age - 0.88 × FLR% + 128 × ICGK - 1.48 × Max Bil (mg/dl) - 21.2 × chemotherapy. The value obtained using this formula significantly correlated with the actual value (r = 0.72, p < 0.001). A 10-fold cross validation also showed significant correlation (r = 0.62, p < 0.001), and a hypertrophy ratio <20% was predictable with a sensitivity of 100% and a specificity of 90.9%. Moreover, technetium-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin scintigraphy showed a significantly smaller increase in the uptake ratio of the remnant liver in patients with prediction values <20% than in those with values ≥20% (6.8 vs. 20.8%, p = 0.030). Conclusions: The prediction formula can prognosticate the hypertrophy ratio after PVE, which may provide a new therapeutic strategy for major hepatectomy

Impact of Hepatic Steatosis on Disease-Free Survival in Patients with Non-B Non-C Hepatocellular Carcinoma Undergoing Hepatic Resection.

[Background]Although the prevalence of non-B non-C hepatocellular carcinoma (NBNC HCC) has increased, its clinicopathologic characteristics remain unclear. [Methods]We retrospectively analyzed 518 HCC patients who underwent hepatic resection. Hepatitis B surface antigen- and hepatitis C antibody-negative patients were categorized into the NBNC HCC group (n = 145); others were categorized into the hepatitis B or C HCC (BC HCC) group (n = 373). We subdivided the etiologies of NBNC HCC according to alcohol intake and presence of steatosis. [Results]NBNC HCC was associated with nonalcoholic fatty liver disease (NAFLD) (13.1 %), fatty liver disease with moderate alcohol intake (9.0 %), alcoholic liver disease (ALD) (29.7 %), cryptogenic disease (44.1 %), and other known etiologies (4.1 %). The prevalence of obesity, diabetes mellitus, and hypertension was higher and hepatic function was better in the NBNC HCC group, which had significantly larger tumors than the BC HCC group. The entire NBNC HCC group displayed similar overall and disease-free survival as the BC HCC group. Among the subdivisions, NAFLD-associated HCC patients had significantly better disease-free survival than ALD-associated HCC and BC HCC patients. Microvascular invasion (hazard ratio [HR] 2.30; 95 % confidence interval [CI] 1.33–3.96) and steatosis area <5 % of noncancerous region (HR 2.13; 95 % CI 1.21–3.93) were associated with disease-free survival in NBNC HCC patients. [Conclusions]The prognosis of NBNC HCC was similar to that of BC HCC. Among NBNC HCC patients, NAFLD-associated HCC patients had a relatively low recurrence risk. Absence of steatosis in hepatic parenchyma had a significant impact on disease-free survival in NBNC HCC patients

Successful management of unstable angina in a ravulizumab-treated patient with paroxysmal nocturnal hemoglobinuria

Ravulizumab is an anti-C5 antibody approved for treating paroxysmal nocturnal hemoglobinuria (PNH). In August 2019, a 77-year-old Japanese man with PNH, who had been on ravulizumab treatment for 2 years, was hospitalized for chest discomfort and malaise. Electrocardiography identified a right bundle block, and elevated serum troponin I and d-dimer suggested ischemic heart disease. Cardiac catheterization revealed severe stenosis in the left anterior descending coronary artery, and intracoronary stenting relieved his chest discomfort. The final diagnosis was unstable angina unrelated to ravulizumab, and the patient's ravulizumab treatment was uninterrupted with no significant complications of PNH. This case report highlights the importance of continuing complement inhibition therapy during acute coronary events

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure &lt; 100 mmHg (n = 1127), estimated glomerular filtration rate &lt; 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Comparative study of autonomous path-following vehicle control via model predictive control and linear quadratic control

This paper describes a comparative study of steering and yaw moment control manoeuvres in the model predictive control and linear quadratic control approaches for path-following control of an autonomous vehicle. We present the effectiveness of the model predictive control and linear quadratic control approaches for stability control of the vehicle’s lateral position and yaw angle for different control manoeuvres: two-wheel steering, four-wheel steering and direct yaw moment control. We then propose model predictive control with a feedforward controller to minimize the tracking errors of the lateral position and the yaw angle in an active front steering manoeuvre, and these are compared with the results from linear quadratic control that has a feedforward controller. Model predictive control is designed on the basis of the simple yaw–lateral motions of a single-track vehicle with a linear tyre model (i.e. a bicycle model), which is an approximation of the more realistic model of a vehicle with double-track yaw–roll motion with a non-linear tyre model (i.e. the Pacejka model). The linear quadratic controller is designed on the basis of the same approach as adopted for the model predictive controller to achieve a fair comparison. On the basis of a given trajectory, we simulate the manoeuvre of the vehicle at a low speed, a middle speed and a high speed because load transfer effects will influence the roll dynamics especially at a high speed. We also perform simulations on low-road-friction surfaces in a double-lane-change scenario with the aim of following the desired trajectory as closely as possible while maintaining the vehicle stability. The simulation results show that model predictive control through two-wheel steering and four-wheel steering with direct yaw moment control performed better in terms of trajectory tracking at a high forward speed and low road surface variation. The proposed model predictive control with a feedforward controller is shown to be effective in minimizing the trajectory tracking errors. For all control manoeuvres, model predictive control gives a better tracking performance than linear quadratic control does. In addition, when the roll dynamics are considered, model predictive control significantly improves the vehicle stability and the trajectory along the desired path